Dissertations / Theses on the topic 'Discharge of thermal waters'

Liquid waste discharged from industrial outfalls is categorized into two major classes based on their density. One type is the effluent that has a higher density than that of the ambient water body. In this case, the discharged effluent has a tendency to sink as a negatively buoyant jet. The second type is the effluent that has a lower density than that of the ambient water body and is hence defined as a (positively) buoyant jet that causes the effluent to rise. Negatively/Positively buoyant jets are found in various civil and environmental engineering projects: discharges of desalination plants, discharges of cooling water from nuclear power plants turbines, mixing chambers, etc. This thesis investigated the mixing and dispersion characteristics of such jets numerically. In this thesis, mixing behavior of these jets is studied using a finite volume model (OpenFOAM). Various turbulence models have been applied in the numerical model to assess the accuracy of turbulence models in predicting the effluent discharges in submerged outfalls. Four Linear Eddy Viscosity Models (LEVMs) are used in the positively buoyant wall jet model for discharging of heated waste including: standard k-ε, RNG k-ε, realizable k-ε and SST k-ω turbulence models. It was found that RNG k-ε, and realizable k-ε turbulence models performed better among the four models chosen. Then, in the next step, numerical simulations of 30˚ and 45˚ inclined dense turbulent jets in stationary ambient water have been conducted. These two angles are examined in this study due to lower terminal rise height for 30˚ and 45˚, which is very important for discharges of effluent in shallow waters compared to higher angles. Five Reynolds-Averaged Navier-Stokes (RANS) turbulence models are applied to evaluate the accuracy of CFD predictions. These models include two LEVMs: RNG k-ε, and realizable k-ε; one Nonlinear Eddy Viscosity Model (NLEVM): Nonlinear k-ε; and two Reynolds Stress Models (RSMs): LRR and Launder-Gibson. It has been observed that the LRR turbulence model as well as the realizable k-ε model predict the flow more accurately among the various turbulence models studied herein.

The concerns of global warming are guiding most industries and commercial properties towards addressing their energy usage. In large buildings where air conditioning is required, there is often a need for “chillers” to control the temperature of the building. This process is not environmentally friendly and expensive in terms of energy used and maintenance issues. The alternative is to cool buildings using natural resources such as induced wind drafts and water extraction from rivers and canal. The latter has not been used with optimum effectiveness because the prediction procedures are not sufficiently developed to satisfy environmental legislation. The mathematical approaches are unrealistic and extremely conservative in their analysis and this causes many valid proposals to be rejected. This research is aimed at addressing that situation. It will provide a valid interactive 3-dimensional analysis procedure that will better evaluate the potential of using any British Waterways canal or similar water source for cooling purposes. After water has been used for cooling it is returned to the canal in a heated state as a thermal plume. It is the boundaries of the plume that must be predicted with reasonable accuracy so that environmental legislation is not infringed and livestock is not jeopardised. It is equally important to ensure the analysis is not over sensitive so as to result in rejection of valid proposals. Earlier work studied heat distribution but did not consider the thermal discharge into still and shallow water, as in a British Waterways canal. The studies below investigate several canal sites to evaluate a variety of situations where the discharge plume differs. Criteria including discharge direction, volume of water, temperature differences, speed of discharge and depth of discharge pipe all play a part in the formation of the plume. As such it is possible to develop an understanding of how the thermal plume merges into the still water and how the heat is diffused into the general body of water. In conjunction with site measurements a laboratory experimental scale model tank was built to replicate the real canal site. This allowed data to be varied and measured more readily. Two different types of discharge have been the subject of this research - the first being when the discharge pipe is located at the surface of the receiving water, the second being when it is submerged deeply below the surface. In all cases the temperature and velocity are measured at various points and at a variety of depths to provide a three dimensional plot across the mixing zone. In addition to the mathematical analysis, thermal imaging was used to predict the heat diffusion profiles on the surface of the receiving water in both the canal site and the model tank. CFD software is also used to evaluate the distribution of temperature and velocity within the mixing zone. The mathematical analysis produced an equation to predict the heat diffusion profile in surface discharge. And a number of equations were produced to model the plume path line in submerged discharge- relating to temperature and velocity dilution along and across the path lines. The relative effects of the bed and free surface proximity appeared significantly in the equations. A 3-dimensional model of the size of the plume is presented to demonstrate the results. The procedure followed in this study will enable the Environment Agency personnel to assess the waste heat utilization with greater thoroughness and within a shorter period.

This thesis examined the thermoregulatory and neuromuscular responses to passive heating in 42 °C hot water. The data suggest that hot-water immersion at 42 °C is an efficient, safe and tolerable method for passive heating therapy. Moreover, a single session of hot-water immersion can increase rapid force production and improve muscle contractile function. Findings from this thesis indicate that passive heating via hot baths may improve physical function in the older and patient populations and assist healthy people during sports injury recovery.

The use of cold atmospheric pressure plasma for applications related to microbial decontamination has grown enormously over the last decade. Non-thermal plasmas generated in ambient air contain a wide variety of reactive oxygen and nitrogen species, or RONS. When such species interact with microorganisms they induce a number of biological changes, ultimately resulting in inactivation of the organism. This thesis focuses on the design, development, optimisation and application of air plasma systems for microbial decontamination. The aim of the work is to gain a better understanding of how RONS are produced in air plasma and how they are transported through different phases of matter, including gases and liquids. It is shown that RONS generation is highly dependent on the discharge conditions and two distinct modes of operation are observed. Downstream of the discharge, the transport of RONS to the sample region is of paramount importance as many highly-reactive species are lost. To address this challenge, the structure of the plasma generating electrodes was systematically studied to optimise the plasma generated air flow and therefore the transport of species downstream. Optimised electrode structures were shown to generate flow velocities in excess of 1m/s which is an order of magnitude improvement over transport by diffusion alone. Using the optimised plasma system, the impact of RONS in real decontamination scenarios linked to food and water security were considered. This included investigation of plasma decontamination of liquid samples, solid surfaces and tissues. It was shown that plasma decontamination can be extremely effective but many factors influence the efficacy of the approach. Microorganisms shielded within a liquid layer or by a complex surface morphology were shown to be particularly difficult to inactivate. Overall, this work has demonstrated that plasma can be a highly effective tool for microbial decontamination but careful consideration of both the discharge parameters and the sample properties is required to achieve the highest level of decontamination.

Recent interest in hydrogen as an energy source has resulted in development of new technologies such as non-thermal plasma processing of natural gas. We report the development of a process yielding hydrogen from natural gas that generates no green house gases and thus meets the Kyoto accord targets.<br>In this process, natural gas is treated in a dielectric barrier discharge (DBD) yielding hydrogen and solid carbon according to the following reaction: CH4 (g) → 2H2 (g) + C (s). The direct cracking of the hydrocarbon is possible if the natural gas is injected in the plasma zone, created by the presence of a dielectric ceramic material.<br>It was found that the dielectric material plays an important role on plasma intensity. The change in ceramic properties affects the parameters of the discharge. It was discovered that the number of micro-discharges increased when a ceramic with a higher dielectric constant was used. Furthermore, the ceramic relative permittivity or dielectric constant has a direct influence on the hydrogen yield.<br>However, the challenge is that when using a commercial high dielectric ceramic as barrier they tend to break in the plasma environment. In the attempt of improving the process efficiency medium permittivity dielectric ceramics (9 < K' <166) were fabricated and successfully tested in the discharge reactor. A broad variety of ceramics (from low to high permittivity) were tested and the results suggested that the CH4 conversion using high dielectric constant barrier is much higher than using conventional barrier material such as A12O3.

This Research is devoted in modifying the technology of desalination such as the multi-stage flash and the multi effect distillation. The main motive behind this research is to make these mentioned technologies use least electrical energy so that they can be integrated with renewable sources such as solar, wind etc. Secondly, use the waste discharge brine to collect salts so that we can use those salts as thermal energy storage medium. The highlight of this study is the use of wasteful discharge to make desalination zero discharge. The thesis is therefore titled as Thermal Driven Desalination with zero discharge. As the title of this thesis suggests, this work is a combination of 3 stages of research. The first stage is the development of a program for the calculation of various mass flow rates and other parameters. The program developed mainly uses the first law of thermodynamics namely mass and energy balance. The program allows us to predict these flow rates and other parameters to design our system. The second stage of this study is the 3-D modelling and design of various assemblies like the Full separation tank, effects, heating strategy, control strategy and heat exchanger required in the system. We therefore compared the area obtained from the program and that used in the prototype and observed the changes and differences. Thirdly, this system is implemented by fabrication of a prototype. The prototype is developed to showcase the validity of the concept. The prototype would validate the simulation values as well as allow us to justify our concept behind this system. The prototype although gave a few problems during various experiment runs and hence requires more work.

Thesis (Ph. D.)--Joint Program in Marine Geology and Geophysics (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), September 2003.<br>Includes bibliographical references.<br>Groundwater discharge into estuaries and the coastal ocean is an important mechanism for the transport of dissolved chemical species to coastal waters. Because many dissolved species are present in groundwater in concentrations that are orders of magnitude higher than typical river concentrations, groundwater-borne nutrients and pollutants can have a substantial impact on the chemistry and biology of estuaries and the coastal ocean. However, direct fluxes of groundwater into the coastal ocean (submarine groundwater discharge, or SGD) can be difficult to quantify. Geochemical tracers of groundwater discharge can reflect the cumulative SGD flux from numerous small, widely dispersed, and perhaps ephemeral sources such as springs, seeps, and diffuse discharge. The natural radiocarbon content (A14C) of dissolved inorganic carbon (DIC) was developed as a tracer of fresh, terrestrially driven fluxes from confined aquifers. This A14C method was tested during five sampling periods from November 1999 to April 2002 in two small estuaries in southeastern North Carolina. In coastal North Carolina, fresh water artesian discharge is characterized by a low A14C signature acquired from the carbonate aquifer rock. Mixing models were used to evaluate the inputs from potential sources of DIC-A'4C to each estuary, including seawater, springs, fresh water stream inputs, and salt marsh respiration DIC additions. These calculations showed that artesian discharge dominated the total fresh water input to these estuaries during nearly all sampling periods.<br>(cont.) These new A14C-based SGD estimates were compared with groundwater flux estimates derived from radium isotopes and from radon-222. It is clear that these tracers reflect different components of the total SGD. The fluxes of low-A14C and of 222Rn were dominated by artesian discharge. Estuarine 226Ra showed strong artesian influence, but also reflected the salt water SGD processes that controlled the other three radium isotopes. The flux of 228Ra seemed to reflect seepage from the terrestrial surficial aquifer as well as salt water recirculation through estuarine sediments. The fluxes of 224Ra and 223Ra were dominated by salt water recirculation through salt marsh sediments. This multi-tracer approach provides a comprehensive assessment of the various components contributing to the total SGD.<br>by Carolyn M. Gramling.<br>Ph.D.

This study combined concentration-discharge analyses (filtration at 0.45 m), cascade filtrations (at 1.2, 0.4, and 0.025 m) and asymmetrical flow field flow fractionation (AF4) to probe the influence of colloidal carriers (dissolved organic matter and inorganic nanoparticles) on observed concentration-discharge relationships for trace metals in a 155 ha forested catchment of the Santa Catalina Mountains Critical Zone Observatory (SCM CZO), Arizona. Many major elements (Na, Mg, Si, K, Ca) show no colloidal influence, and concentration-discharge relationships for these species are explained by previous work. However, the majority of trace metals (Al, Ti, V, Mn, Fe, Cu, Y, REE, U) show at least some influence of colloids on chemistry when filtered at the standard 0.45 m cutoff. Concentration-discharge slopes of trace metals with modest colloidal influence are shallow (approximate to 0.3) similar to that measured for dissolved organic carbon (DOC, 0.24), whereas elements with greater colloidal influence have steeper concentration-discharge slopes approaching that of Al (0.76), the element with the largest colloidal influence in this study (on average 68%). These findings are further supported by AF4 measurements that show distinct and resolvable pools of low hydrodynamic diameter DOC-sized material coexistent with larger diameter inorganic colloids, and the ratio of these carriers changes systematically with discharge because the DOC pool has a concentration-discharge relationship with shallower slope than the inorganic colloidal pool. Together these data sets illustrate that positive concentration-discharge slopes of trace metals in stream waters may be explained as the relative partitioning of trace metals between DOC and inorganic colloids, with contributions of the latter likely increasing as a result of increased prevalence of macropore flow.

Field measurement and numerical modeling are the most popular and fundamental approaches for studying mixing pattern in rivers and coastal waters. Due to the limitations associated with both of these methods they should be used together to verify each other. Extensive field measurement was conducted on the effluent plume from the outfall of the Capital Region waste water treatment plant in the North Saskatchewan River. Tracer was injected at the outfall location and the mixing pattern was investigated by tracking the tracer concentration over a 83 km reach of the river. Flow velocity and depth were also measured simultaneously using an acoustic Doppler current profiler. An integrated in situ fluorometer-GPS measurement technique was introduced and used for field tracer studies in meandering rivers. The full transverse mixing length for the river was estimated to be 130 km. A stream-tube orthogonal curvilinear mesh generation algorithm was also developed for numerical modeling of meandering rivers. The method eliminates the effect of transverse velocity field using the stream-tube concept. The field measured velocity data were used for calculating the stream tube width in each cross-sectional strip. The stream-tube grid was used to develop a practical and efficient coupled field-numerical model for estimating the transverse mixing coefficient in meandering rivers. In this model the computational costs associated with solving the hydrodynamic sub-model is reduced by generating the velocity field from measured data. Using the calibrated model, the average transverse mixing coefficient was calculated for the surveyed reach. Extensive field study was also conducted on the near-field and far-field of a thermal plume discharged by the Ras Laffan Industrial City in Qatar. Three-dimensional perspective of the plume behavior was obtained using field measured temperature and velocity data. Different characteristics of the observed plume including the extent of different zones of the plume, plume thickness, detachment depth and variation of the minimum dilution were investigated and compared with available theories. The contribution of each effective mixing mechanism was also calculated using the field measured data. Vertical confinement was found to be the main effective parameter on the near-field mixing rate which reduced the minimum dilution rate up to 80%. An innovative remote sensing technique was introduced to investigate the near-field mixing of thermal surface plumes. The method generates a calibrated thermal image of the plume using LandSat thermal infrared (TIR) satellite images. Using a combination of remote sensing and numerical modeling, the near-field dynamics of the plume was found to be influenced by the wind action. It was also observed that the previous classification for determining the effect of wind on the plume dynamics did not successfully predict the plume behavior in shallow water. Two non-dimensional parameters, WI1=Uwl/U0 (ratio of the long-shore wind speed (Uwl) to the discharge velocity (Uo) and WI2= Uwc/U0 (ratio of the cross-shore wind (Uwc) to the discharge velocity), were introduced to quantify the effect of wind on the plume dilution and deflection. The plume trajectory was found to be sensitive to a longshore wind greater than 2 m/s, which is half of the reported value for deep water conditions. The surveyed coastal outfall was also modeled using a nested coupled hydrodynamic-wave approach. Validation of the model with field measured and remote sensing data showed that the employed approach can be used for engineering applications such as designing outfall systems and environmental impact assessment purposes. The calibrated model was used to investigate the effect of various effective factors on the mixing process such as lateral confinement, wave-flow interaction, wave dissipation factors and turbulence models. Lateral confinement was found to reduce the mixing potential of the outfall by 50% at the end of the near-field.

Der Zustrom von Grundwasser zu Seen (lacustrine groundwater discharge, LGD) kann signifikante Auswirkungen auf Qualität und Quantität des Seewassers haben. Viele Ansätze zur Identifikation und Quantifizierung von LGD basieren auf Temperaturunterschieden zwischen Grund- und Seewasser und der Messung des damit einhergehenden Wärmetransports. Ziel der Doktorarbeit ist es, Signalfortpflanzung und -ausbreitung des Grundwasserzustroms von der Punktskala an der Sediment-Wasser-Grenzfläche über den Wasserkörper bis zur Grenzfläche Wasseroberfläche-Atmosphäre zu untersuchen. Getestet wird die Hypothese, dass das im Verhältnis zum Umgebungswasser wärmere und daher leichtere Grundwasser in der kalten Wassersäule aufsteigt und die Detektion von LGD an der Wasseroberfläche mit thermalen Infrarot Aufnahmen (TIR) erlaubt. Zunächst wird mit der hierarchical patch dynamics ein Konzept entwickelt, das eine angemessene Kombination multipler Techniken zur Erfassung von Wärme- und Wasserflüssen anbietet (Kap. 2). Dabei werden verschiedene räumliche Skalen und ökohydrologische Grenzflächen abgedeckt. Darauf basierend werden in einem Mesokosmos-Experiment unterschiedliche LGD-Raten durch den Zustrom von warmem Wasser am Grund eines Outdoor-Pools simuliert (Kap. 3 und 4). Ein Glasfaserkabel (fibre-optic distributed temperature sensing, FO-DTS) wird in verschiedenen Tiefen installiert, um das Wärmesignal des Grundwasserzustroms unter verschiedenen Bedingungen zu verfolgen. Mit einer TIR-Kamera wird die Temperatur des Oberflächenwassers aufgezeichnet. Die Aufnahmen werden mit FO-DTS-Temperaturen von 2 cm unter der Wasseroberfläche validiert. Die Anwendung von TIR und FO-DTS ermöglicht die Detektion von LGD in der Wassersäule und an der Grenzfläche Wasseroberfläche-Atmosphäre. Wolkenbedeckung und der Tagesgang der Netto-Strahlung kontrollieren den Auftrieb von LGD und die Zuverlässigkeit der TIR-Ergebnisse. Die besten Ergebnisse werden bei Bewölkung und nachts erzielt.<br>Lacustrine groundwater discharge (LGD) can have significant impacts on lake water quantity and quality. There is a need to understand LGD mechanisms and to improve measurement methods for LGD. Approaches to identify and quantify LGD are based on significant temperature differences between GW and lake water. The main goal of this PhD thesis is to trace heat signal propagation of LGD from the point scale at the sediment-water interface across the overlying water body to the water surface-atmosphere interface. The PhD thesis tests the hypothesis that the positive buoyancy of warm GW causes upwelling across the cold water column and allows detection of LGD at the water surface by thermal infrared imaging (TIR). First, a general conceptual framework is developed based on hierarchical patch dynamics (HPD). It guides researchers on adequately combining multiple heat tracing techniques to identify and quantify heat and water exchange over several spatial scales and ecohydrological interfaces (Chapter 2). Second, the conceptual framework is used for the design of a mesocosm experiment (Chapters 3 and 4). Different LGD rates were simulated by injecting relatively warm water at the bottom of an outdoor mesocosm. A fiber optic distributed temperature sensing (FO-DTS) cable was installed in a 3D setup in the water column to trace the heat signal of the simulated LGD under different weather conditions and over entire diurnal cycles. Finally, a TIR camera was mounted 4 meters above the mesocosm to monitor water surface temperatures. TIR images were validated using FO-DTS temperature data 2 cm below the water surface (Chapter 4). The positive buoyancy of relatively warm LGD allows the detection of GW across the water column and at the water surface-atmosphere interface by FO-DTS and TIR. Cloud cover and diurnal cycle of net radiation strongly control the upwelling of simulated LGD and the reliability of TIR for detection of LGD at the water surface-atmosphere interface. Optimal results are obtained under overcast conditions and during night.

Plasma chemistry is a rapidly growing field to develop and exploit the great potential of plasma to perform chemical reactions. This thesis deals with the oxidation of organic pollutants in air and water promoted by the action of air non-thermal plasma (NTP). Such plasmas, which are conveniently produced by electric non-thermalizing discharges like corona and dielectric barrier discharges in air at atmospheric pressure and ambient temperature, provide highly reactive oxidizing environments comprising electrons, excited molecules, atomic and radical species (O, OH), ions (O2+, N2+, NO+, O–, O2–, O3–), O3 and NO. Despite the numerous successful applications of NTP in processes of environmental and commercial relevance, the chemistry of organic compounds within air non-thermal plasmas is still not well characterized, both as far as products and mechanisms are concerned. This thesis developed as a contribution to this field of research along three lines dealing, respectively, with plasma processing of: volatile organic compounds (VOCs) in air with plasma alone; VOCs in air with plasma plus an heterogeneous catalyst; organic pollutants in aqueous solutions above which an air plasma is generated. All three projects had a common focus in the mechanistic characterization of the oxidation processes within these very complex and highly reactive systems. The study of VOC oxidation in air NTP was carried out with a large prototype corona reactor developed at the Department of Chemical Sciences in Padova, which can be energized with DC or pulsed high voltage of either polarity. Comparative studies were carried out to evaluate the response of selected model VOCs to different corona regimes (+DC, −DC and +pulsed). The VOCs considered include two alkanes (n-hexane and i-octane), toluene and two halogenated methanes, dibromomethane (CH2Br2) and dibromodifluoromethane (CF2Br2, halon 1202). Remarkably, all these different VOCs, including the highly inert halon, can be oxidized to CO2 at room temperature with efficiencies which depend on VOC type (despite their high reactivity NTPs display some selectivity), on VOC concentration (the efficiency increases linearly with the reciprocal of VOC concentration) but also on the way energy is given to the plasma. Thus, for all VOCs examined the efficiency decreases in the order: +pulsed > -DC > +DC corona. This means that any given amount of energy produces an extent of VOC conversion ([VOC]/[VOC]0) which depends on the corona regime and decreases in the order +pulsed > –DC > +DC. The greater efficiency of +pulsed corona is due to the higher mean electron energy achieved, for any given input of energy, with this type of power supply with respect to DC high voltage. The mean electron energy of the plasma under the different corona regimes was experimentally determined in our reactor by emission spectroscopy measurements following a published procedure. Another important variable tested was the humidity in the air, which is known to produce the strongly oxidizing OH radicals via electron induced dissociation or via reaction with O2+ and N2+ ions. Thus, the greater efficiency in humid with respect to dry air observed for the oxidation of hydrocarbons and of CH2Br2 with –DC and +pulsed corona was attributed to reaction with OH radicals. Surprisingly, in experiments with + DC the same VOCs undergo less efficient oxidation in humid air than in dry air, despite the presence of OH radicals. Analysis of the plasma ionized species, performed by APCI-MS (Atmospheric Pressure Chemical Ionization – Mass Spectrometry), coupled to the determination of current/voltage characteristics of DC coronas, led to the proposal that in the case of +DC corona the oxidation of hydrocarbons and of CH2Br2 is initiated by reactions with ions (O2+, H3O+ and their hydrates, NO+) both in dry as well as in humid air. In contrast, with –DC and +pulsed corona in humid air, OH radicals are involved in the initial stage of hydrocarbons and of CH2Br2 oxidation. Consistent with its very low reactivity with the OH radical, the oxidation of CF2Br2 in humid air proceeds less efficiently with both +DC and –DC corona. It was thus proposed that the oxidation of CF2Br2 occurs via a common mechanism under all corona regimes tested, the initial step being electron induced C-Br dissociation. The process efficiency is lower in humid air because the mean electron energy is lowered due to reaction of the electrons with water molecules. The two halomethanes also form different products: FTIR analysis of post-discharge gas has shown that CH2Br2 produces both CO2 and CO, whereas CF2Br2 forms CO2 and F2C=O. The latter product is a longlived oxidation intermediate due to its low reactivity with atmospheric radicals. It is however very rapidly hydrolized to CO2 and HF as shown by combined ion chromatography and FT-IR analysis of the solution and of the exhaust gas obtained after a water scrubbing step. Other non-carbon containing products of the discharge were analyzed by FT-IR analysis, including ozone, HNO3 and N2O. In experiments with both halomethanes evidence was found for brominesustained catalytic ozone destruction cycles, responsible also for increased conversion of NOx into HNO3. Efficiency and, especially, product selectivity can be improved by the combined action of plasma and heterogeneous catalysts which usually result in synergic effects. The nature and origin of this synergy was the focus of the research I carried out in my second year in graduate school during a stage at the Advanced Industrial Science and Technology Institute (AIST) in Tsukuba (Japan), in the group of dr. Hyun-Ha Kim. As molecular probe to compare the effects of plasma alone and plasma plus catalyst we selected the O-scrambling reaction to form 16O18O starting from a mixture of 16O2 and 18O2. Four different reactors were used and various catalysts, including TiO2, MS-13X and gAl2O3 also containing a few % of Ag. It was possible to conclude that, in the absence of a catalyst the O-exchange reaction occurs in the gas phase and not on the electrodes surface. It was also possible to use the results of these experiments to estimate, for any given energy input the average concentration of O atoms within the plasma. This is a most interesting outcome of these studies since the traditional method for obtaining O atom density involves sophisticated laser spectroscopy instrumentation and procedures. As for the catalyst/plasma interaction, using again a labelled molecular probe, 18O2, it was possible to conclude that the plasma induces oxygen fission on the catalyst surface and that this oxygen is then used in the oxidation of VOCs. The third project dealt with the plasma induced oxidation of phenol in aqueous solution. For these studies two prototype reactors were developed and tested, both characterized by application of electric discharges in the air above the solution. The first is a dielectric barrier discharge reactor which afforded the efficient removal of phenol from the aqueous solution according to an exponential decay as a function of treatment time at constant power. A qualitative analysis of the intermediate and final products of phenol oxidation was performed and the major reactive species formed upon the application of the discharge in air were identified and determined. It is concluded that the decomposition of phenol is initiated by reactions with ozone, taking place on the surface of the solution, and with hydroxyl radicals, both at the surface and within the bulk of the solution. An interesting and most convenient result is the better efficiency of phenol removal in tap water than in milliQ water. After ruling out possible effects due to conductivity, to Fenton’s reaction due to Fe2+ and to active chlorine, it was concluded that the efficiency increase is due to the higher pH of the solution mantained by the presence of bicarbonate salts. The second developed reactor allowed us to perform some interesting comparisons since it can be powered by different types of high voltage for the generation of plasma. The possibility to apply this technology to the treatment of waste water depends on many factors: the process efficiency, the final composition of the treated solution, the general applicability of the system to the organic pollutants. The data obtained so far are very promising due to the efficient oxidation all the way to CO2 and to the absence of any hazardous organic byproduct after a proper treatment time. The results of this thesis confirm that plasma processing is a promising highly efficient means for the advanced oxidation of organic pollutants both in air and in aqueous solution.<br>Lo studio di processi chimici indotti da plasmi sta suscitando un notevole interesse per il grande potenziale che questi sistemi possono sviluppare. Questa tesi riguarda l’ossidazione di inquinanti organici in aria e in soluzione acquosa promossa dall’interazione con plasma non-termico (NTP). Questi plasmi, che sono convenientemente generati da scariche elettriche non termalizzanti, principalmente scariche corona e a barriera di dielettrico, in aria a temperatura e pressione ambiente, costituiscono ambienti di reazione molto reattivi e fortemente ossidanti per la presenza di elettroni, molecole eccitate, specie atomiche e radicali (O, OH), ioni (O2+, N2+, NO+, O–, O2–, O3–), O3 e NO. Nonostante siano numerose le applicazioni tecnologiche di questi plasmi in processi di rilevanza ambientale e commerciale, la chimica dei composti organici in questi sistemi è tuttora non ben nota sia per quanto riguarda i prodotti che i meccanismi di reazione. Questa tesi è uno studio meccanicistico che si è sviluppato lungo tre linee di ricerca riguardanti l’ossidazione di: i) composti organici volatili (VOC) in aria con solo plasma; ii) VOC in aria con plasma e un catalizzatore eterogeno; inquinanti organici in soluzioni acquose poste a contatto con plasma non termico in aria. I tre progetti hanno un obiettivo comune che riguarda la caratterizzazione dei meccanismi di ossidazione che operano in questi sistemi di enorme complessità chimica. Lo studio dell’ossidazione di VOC in plasmi non termici in aria è stato condotto utilizzando un reattore prototipo a scarica corona sviluppato presso il Dipartimento di Scienze Chimiche a Padova, che può essere alimentato da alta tensione DC o ad impulsi di polarità sia positiva che negativa. Sono stati svolti studi comparativi per valutare la risposta di alcuni modelli di VOC a diversi regimi di scarica corona, precisamente +DC, -DC e +pulsed. I composti studiati sono due alcani (esano ed iso-ottano), il toluene e gli alometani dibromometano (CH2Br2) e dibromodifluorometane (CF2Br2, halon 1202). E’ notevole il fatto che tutti questi VOC, compreso l’halon notoriamente molto inerte, possono essere ossidati a CO2 in questi plasmi a temperatura ambiente con un’efficienza che dipende dal tipo di VOC (nonostante la loro elevata reattività questi plasmi presentano comunque un certo grado di selettività), dalla concentrazione del VOC (l’efficienza aumenta linearmente col reciproco della concentrazione iniziale del VOC) e dal modo in cui l’energia viene fornita al reattore. Infatti, per tutti i VOC considerati, l’efficienza del trattamento aumenta nell’ordine: +DC < -DC < +pulsed. Questo significa che il grado di conversione ([VOC]/[VOC]0) prodotto da una certa quantità di energia fornita al sistema dipende dal tipo di scarica utilizzato, che a sua volta determina la composizione e natura del plasma e quindi la sua reattività. La maggiore efficienza del corona ad impulsi rispetto al corona DC è attribuibile alla maggiore energia media degli elettroni in questo regime di scarica. L’energia media degli elettroni è stata determinata sperimentalmente nel nostro reattore nelle diverse condizioni di scarica mediante esperimenti di spettroscopia di emissione utilizzando un metodo pubblicato in letteratura. Un’altra importante variabile di questi processi è il grado di umidità dell’aria, che determina la formazione di maggiori o minori concentrazioni del radicale OH. Questo radicale si forma dall’acqua attraverso reazione con elettroni ad alta energia o reazione con gli ioni O2+ and N2+. La maggior efficienza dell’ossidazione di idrocarburi e del CH2Br2 osservata con -DC in aria umida rispetto all’aria secca è stata quindi attribuita alla reazione con radicali OH. Sorprendentemente, con +DC l’umidità produce un effetto opposto per gli stessi VOC, nonostante la presenza in aria umida di radicali OH. L’analisi degli ioni del plasma, effettuata mediante spettrometria di massa APCI-MS (Atmospheric Pressure Chemical Ionization – Mass Spectrometry), accoppiata allo studio della caratteristica corrente/tensione del corona DC, ha portato a concludere che nel caso del corona +DC l’ossidazione degli idrocarburi e del dibromometano è iniziata da reazione con ioni (O2+, H3O+ e i loro idrati, NO+) sia in aria secca che in aria umida. Al contrario, nel caso del corona –DC e del corona +pulsed la principale reazione di attacco a questi VOC risulta essere quella del radicale OH. Per quanto riguarda invece l’halon CF2Br2, sia con +DC che con –DC l’ossidazione in aria umida risulta meno efficiente che in aria secca, un risultato coerente con la nota scarsa reattività di questo VOC con il radicale OH. E’ stata quindi avanzata l’ipotesi che l’ossidazione di questo halon proceda attraverso un meccanismo comune, indipendentemente dal regime di scarica applicato, che comporta la dissociazione iniziale del legame C-Br indotta da interazione con elettroni del plasma. Il processo è meno efficiente in aria umida probabilmente perché la reazione di dissociazione dell’acqua provoca una riduzione dell’energia media degli elettroni rispetto a quella in aria secca. L’ossidazione dei due alometani in aria secca dà prodotti diversi: l’analisi FT-IR del gas in uscita dal reattore ha individuato sia CO2 che CO fra i prodotti di CH2Br2 mentre nel caso di CF2Br2 i prodotti sono CO2 e F2C=O. Quest’ultimo è un intermedio di ossidazione con tempo di vita sufficientemente lungo da poter essere rivelato in quanto notoriamente poco reattivo nelle reazioni con radicali. E’ tuttavia idrolizzato molto velocemente a CO2 e HF come dimostrato da analisi integrate di cromatografia ionica e FT-IR della soluzione e del gas ottenuti dopo gorgogliamento del gas trattato in acqua. Altri prodotti di questi trattamenti rivelati e quantificati mediante spettroscopia FT-IR sono l’ozono, l’acido nitrico e l’ossido N2O. Con entrambi gli alometani si è osservato l’intervento di cicli catalitici di distruzione dell’ozono in cui il bromo atomico è la specie propagatrice. Gli stessi cicli sono inoltre responsabili della conversione degli NOx in HNO3. L’efficienza e la selettività dei processi di ossidazione al plasma possono essere migliorati attraverso l’azione combinata del plasma e di catalizzatori eterogenei. Ne deriva un effetto sinergico, la cui origine e natura sono tuttora in fase di studio. Di questo problema mi sono occupato durante un soggiorno presso l’Advanced Industrial Science and Technology Institute (AIST) a Tsukuba (Giappone), presso il gruppo del Prof. Hyun-Ha Kim. Per confrontare gli effetti di solo plasma e plasma più catalizzatore abbiamo utilizzato come sonda molecolare la reazione di scambio di ossigeno che produce 16O18O partendo da miscele di 16O2 e 18O2. Sono stati utilizzati diversi reattori al plasma con diverse alimentazioni elettriche e parecchi catalizzatori fra cui TiO2, MS-13X e gAl2O3 contentente varie modeste percentuali di Ag. Questi studi hanno permesso di concludere che, in assenza di catalizzatore, la reazione di scambio di ossigeno avviene in fase gas e non sulle superfici degli elettrodi. I risultati di questi esperimenti sono stati utilizzati per sviluppare un metodo basato sulla reazione di scambio isotopico al fine di determinare la concentrazione di ossigeno atomico in questi plasmi. Questo è un risultante importante che si propone come alternativa al metodo tradizionale per la determinazione della concentrazione di ossigeno atomico con strumentazioni ottiche laser e procedure piuttosto sofisticate. Per quanto riguarda l’interazione catalizzatore/plasma, è stato possibile concludere, sempre utilizzando la sonda molecolare 18O2, marcata isotopicamente, che il plasma determina la fissazione dell’ossigeno sulla superficie del catalizzatore e che questo ossigeno è quindi trasferito al VOC nel processo di ossidazione. Infine, il terzo progetto ha riguardato l’ossidazione del fenolo in soluzioni acquose esposte all’azione di plasma non-termico in aria. Per questi studi sono stati sviluppati due prototipi di reattore caratterizzati entrambi dall’applicazione di scariche elettriche nell’aria sovrastante la soluzione da trattare. L’ossidazione del fenolo nel primo reattore, che utilizza scariche a barriera di dielettrico, procede efficacemente fino a CO2 seguendo un decadimento esponenziale in funzione del tempo di trattamento a potenza applicata costante. Dall’analisi dei prodotti ed intermedi di ossidazione nonché dalla determinazione delle principali specie reattive è emerso che la decomposizione del fenolo avviene per reazione con l’ozono sulla superficie della soluzione a contatto con il plasma, e con il radicale OH, sia sulla superficie che all’interno della soluzione. Un risultato molto interessante e utile in vista di applicazioni pratiche di questi processi riguarda la maggiore efficienza dell’ossidazione del fenolo in acqua di rubinetto rispetto all’acqua milliQ. Dopo aver escluso che all’origine di questo fenomeno potessero esserci effetti dovuti alla conduttività maggiore, alla presenza di ioni Fe2+ capaci di indurre la reazione di Fenton, e alla presenza di cloro attivo nell’acqua potabile, è stato verificato che l’effetto tampone esercitato dallo ione bicarbonato mantiene un pH elevato e consente al processo di procedere velocemente.

Environmental destruction, global warming and limited potable water resources are problems often mentioned in opinion polls that ask the public to identify major problems to be solved, this century. Demand for freshwater continues to grow, but sufficient natural sources are not always available. One solution is to supply potable water from seawater using desalination technology. Most conventional desalination systems are very energy intensive and use energy supplied by fossil fuels. There is a new interest to utilise low grade energy and couple a desalinator with a thermal process such as oil, gas or utility plant to produce both freshwater and power. The aim of this research is to design and evaluate a novel heat recovery system, which can cogenerate freshwater and power. Discharge thermal energy combined desalination (DTECD) with a power cycle utilises a waste heat stream as an energy source, which is available in some energy intensive plants such as ammonia or gas processing plant. DTECD includes two sub-systems: closed power cycle and open water cycle. At the core of the open water cycle is a vacuum spray flash evaporator (VSFE), which is based on low temperature thermal desalination system. The new VSFE system utilises a gas-liquid ejector to consume less energy and enable greater ease of operation compared to conventional vacuum desalinators, which use a vacuum pump or steam jet ejector. The feasibility of the proposed DTECD process was evaluated by applying the ASPEN/HYSYS V8.0. Two configurations of process were modelled and the results were validated based on the waste heat of two industrial case studies: ammonia and gas processing plants. Subsequently, the performance of the proposed process was evaluated by using an exergy approach, thermodynamic modelling and a thermo-economic study. The bottlenecks of the DTECD process were improved by parametric optimisation and process modification. The results revealed that the overall exergy efficiency of the proposed heat recovery system is about 50% and this is an economic option to couple with a thermal plant. Furthermore, the core VSFE system has been designed and manufactured for the experimental study of: (i) the performance of suggested downward gas-liquid ejector (eductor), (ii) the effects of temperature and salinity of motive fluid on overall performance of the eductor and desalination system. Numerical models of two-phase flow, based on the thermodynamic model and transfer phenomena were applied to the VSFE system. Experimental conditions were compared with a predictive model to find its accuracy. Computational fluid dynamic (CFD) method, which is embedded in ANSYS/Fluent 16.2 was undertaken to investigate the individual conversion laws inside the vessel. Based on the physics of VSFE, a discrete phase model (DPM) is needed to investigate the spray of saline water under vacuum conditions. The experimental data proved that the performance of the VSFE system is in good agreement with theoretical model and utilising a downward eductor with saline water as motive fluid is an economic option to generate the required vacuum. Also, the CFD results showed that the evaporation rate of the system follows the experimental data and the optimum geometry of the VSFE affects the overall performance. Finally, general aspects of working fluids in the proposed process and applications of wire mesh nozzle vs. spiral nozzle in desalinator are discussed.

Este trabalho lança novos dados em relação à gênese das águas termais da região centro-sul da Borda Oriental do Estado de Santa Catarina. Pouco se sabe a este respeito, apesar das águas termais serem exploradas a mais de 180 anos no Estado de Santa Catarina, pouco se falou sobre sua gênese e evolução. Neste trabalho foram reunidos os dados existentes sobre as águas termais e termo-minerais no Estado de Santa Catarina até o presente momento e compilados na forma de tabelas, quadros e modelos genéticos, o que possibilitou lançar novas hipóteses sobre as origens destas águas. Não foram consideradas as ocorrências a Oeste de Santa Catarina por serem captações feitas por poços tubulares profundos e não por surgências naturais ou poços pouco profundos, como ocorre na região centro-sul da Borda Oriental.<br>This work intends to dare new basis in relation to the origin of the thermal and thermal-mineral waters in the Centre-South of the Eastern Cost in the state of Santa Catarina. Only a few information about it is available, in spite of the thermal and thermal-mineral waters are being explored over 180 years in the state of Santa Catarina, a few was spoken about their origin and evolution. In this work were joined the information available about the thermal and thermalmineral waters in the state of Santa Catarina until the present moment and compiled in schedules and genetic models that permited to criate new hypothesis about the origin of those waters. The accurences in the West of Santa Catarina were not considered because the captivating is done by deep tubular wells and not by natural existence or by less deep wells like occurs in the Centre-South and the Eastern Cost.

A screening level ecological risk assessment (SERA) was completed to evaluate the potential risks of pesticides found in water in the lower Canal 111 (C-111) Basin and adjacent tidal zones in South Florida. This risk assessment was conducted under general U.S. EPA guidelines and focuses on effects of water exposure to the herbicides atrazine and metolachlor and to the insecticides chlorpyrifos, endosulfan, and malathion. Results found that the highest potential risk was associated with the acute effects of endosulfan to freshwater arthropods at sites near water control structure S-178 and Canal 111e, a branch of C-111. The highest potential risk of acute effects of endosulfan for saltwater organisms was in Joe Bay, which receives discharges from C-111. Results from evaluations of risk of chronic effects from pesticide exposure show that the highest potential risk is associated with endosulfan in freshwater.

Orientador: Roberto Benedito de Paiva e Silva<br>Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas<br>Made available in DSpace on 2018-08-26T05:23:13Z (GMT). No. of bitstreams: 1 Dahdal_AndreiaBenati_M.pdf: 819963 bytes, checksum: e8d78dc0c16b56df7e5fb7422a23f686 (MD5) Previous issue date: 2014<br>Resumo: Define-se termalismo como um procedimento natural de tratamento alternativo e ou complementar à medicina tradicional, que se utiliza das águas minerais para se atingir a cura. As estâncias termais por suas características terapêuticas e ambientais são lugares que vão de encontro à prática do termalismo, pois atende um conjunto de elementos fundamentais, como localização geográfica, rede hoteleira e balneária. Os encaminhamentos para os tratamentos termais deixaram de ser um procedimento médico para tornar-se ao longo da história um procedimento de relaxamento, descanso e de cura por demanda própria associada ao turismo. Neste sentido, o objetivo deste estudo foi conhecer o perfil das pessoas e as razões pelas quais elas procuram o balneário de Águas de Lindóia. É um estudo de caráter qualitativo e participaram da pesquisa vinte e dois usuários do balneário, sendo que os critérios de inclusão foram homens e mulheres adultos frequentadores do balneário para utilização dos recursos termais oferecidos. Realizou-se uma entrevista semiestruturada no próprio balneário, após o usuário concordar e assinar o termo de consentimento livre e esclarecido que foi aprovado pelo Comitê de Ética da Unicamp. Para a análise dos dados utilizou-se a técnica de análise de conteúdo na qual se estabeleceram quatro categorias temáticas: perfil sócio demográfico das pessoas que procuram o balneário de Águas de Lindóia como destino turístico, o uso dos tratamentos oferecidos pelo balneário e o significado das águas como recurso terapêutico. O usuário do balneário se caracteriza por ser em sua maioria do sexo feminino, com idade média de sessenta anos e aposentada que procuram nas técnicas termais o equilíbrio orgânico e mental. Constatou-se que Águas de Lindóia no transcorrer da sua história vem se constituindo em polo turístico voltado ao lazer centrado em sua localização geografia, nos recursos termais e na rede hoteleira. Observou-se a ausência de turistas mais jovens nas dependências do balneário, a partir desse panorama, percebe-se a necessidade de ampliar a divulgação dos recursos oferecidos pelo balneário e desenvolver condutas que respondam as exigências dos turistas nas diversas faixas etárias. Conclui-se que, a maioria dos participantes do estudo pratica o termalismo de bem estar que abrange a prevenção e promoção da saúde em detrimento ao uso do termalismo clássico oferecido pelo balneário no início de suas atividades, que era o uso das águas como terapia específica para determinada doença<br>Abstract: Thermalism is defined as a natural and alternative treatment procedure or complement to traditional medicine that is used with mineral water to achieve the cure. The spas for its therapeutic and environmental characteristics are places that meet the practice of thermalism, as it serves a number of key elements, such as geographic location, hotel chain and bathhouse. Referrals to thermal treatments are no longer a medical procedure to become throughout history a procedure for rest, relaxation and healing on their demand associated with tourism. In this sense, the objective of this study was to know the profile of the people and the reasons why they seek the Águas de Lindóia bathhouse. It is a qualitative study and participated in the survey twenty-two users of the bathhouse, and the inclusion criteria were adult men and women goers bathhouse to use thermal resources offered. We conducted a semi structured interview in the bathhouse itself, after the user agrees and signing the consent form that was approved by the Ethics Committee of UNICAMP. For data analysis we used the technique of content analysis in which it established four thematic categories: socio demographic profile of those seeking Águas de Lindóia bathhouse as a tourist destination, the use of the treatments offered by the bathhouse and the meaning of waters as a therapeutic resource. The user of the resort is characterized by being mostly female, with an average of sixty and retired seeking thermal techniques in the organic balance and mental. It was found that Águas de Lindóia the course of its history has turned into a tourist hub geared to leisure centers on its geography location, the thermal resources and hotel chain. Observed the absence of younger tourists premises of bathhouse, from this scenario we see the need to broaden the dissemination of resources offered by the bathhouse and develop behaviors that meet the needs of tourists of different ages. We conclude that the majority of study participants practicing thermalism wellness that covers prevention and health promotion over the use of classical thermalism offered by the bathhouse at the beginning of its activities, that was the use of water as a specific therapy for disease<br>Mestrado<br>Interdisciplinaridade e Reabilitação<br>Mestra em Saúde, Interdisciplinaridade e Reabilitação

This master’s thesis relates to the investigation of a thermal plume propagation in a selected coastal area in the Southern Adriatic Sea, which is generated due to heated water release, by an Italian thermal power plant. Available punctual temperature profiles with depth have been used in order to calibrate a numerical model. Open-source suite of solvers TELEMAC-MASCARET has been adopted and turned out to be a powerful tool in order to accomplish the goal; nowadays, numerical modelling represents indeed a crucial component in investigating coastal engineering processes. In building the model, hydrodynamics and wave processes characterizing the area have been coupled. Coupling has been gained by means of the combined use of two of the system’s modules: TELEMAC-3D and TOMAWAC. The former solves the three-dimensional free surface flow equations and the transport-diffusion equations of intrinsic quantities, like temperature, while the latter has been used for the solution of the spectral wave action density conservation equation. The thesis containes indeed details about the whole calibration process, up to the final calibrated model description. Once the model has been calibrated, it has been applied to different possible scenarios. This has been done in order to both test the model and exploit its potential for further studies on the area. In particular, three almost extreme scenarios have been investigated: the first involved the consideration of the worse conditions regarding weather, meaning absence of wind and therefore no waves; the second involved the consideration of the maximum power production operational conditions of the power plant; finally, in the third one, a different blowing wind direction has been considered. The overall purpose consisted in both exploiting a powerful open source solver and calibrating a reliable and easy-manageable model on real measurements, to be adapted and re-used for further applications in the area, at the same time.

Submarine groundwater discharge (SGD) represents a significant portion of the total discharge from coastal aquifers through diffuse seepage and point source springs, but can be difficult to locate. SGD is important as it can be a source of nutrients to estuaries and other coastal ecosystems. In an effort to evaluate geophysical and thermal methods for detecting SGD on the Florida Gulf coast, a suite of water-borne surveys were run in conjunction with aerial thermal imagery over the lower Suwannee River and estuary in March and September 2005. Thermal imagery exploits temperature differences between discharging groundwater and surface water. Thermal images were collected in March (dry season), at the end of winter, and at night to maximize the differences between warm groundwater and colder surface water. Generally pore waters in zones of concentrated SGD should be fresher, and hence more resistive than "background" values. Marine streaming resistivity data can detect pore water resistivity variations and were collected alongside continuous 222Rn and CH4 sampling from surface waters. Naturally occurring tracers, 222Rn and CH4, are used as the "standard" against which resistivity and thermal images are compared. Based on the expected properties of discharging groundwater, we hypothesize that in zones of elected tracer concentrations, increased thermal image temperatures and increased terrain resistivities will be observed. The data set as a whole supports this hypothesis. However, regional-scale correlations are clearly and significantly influenced by factors other than SGD including thermal-image noise, the presence of the fresh/salt water interface, and a large regional tracer gradient generated by a first-order spring. At local scales (tens to hundreds of meters) there are no significant correlations between thermal image temperature and tracer concentrations, due at least in part to flight-line edge effects that dominate the thermal imagery. After correcting for regional trends,significant correlations between tracer concentration and log resistivity exist only in a subset of the data that lies offshore. Because neither thermal imagery nor streaming resistivity data consistently support the hypotheses, this study suggests that neither method by itself is reliable for detecting SGD in this area

Mine abandonment and the discharge of contaminated mine water is recognised globally as a major source of surface water and groundwater pollution. Contamination generally arises from the oxidation of sulphide minerals, principally pyrite, by the mining process, and the subsequent chemical reactions can lead to the discharge of mineralised, often acidic, iron, and sulphate rich waters. In many historically mined river catchments, mine water discharge is the main cause of poor water quality. Within the UK, managing the legacy of abandoned mines is one of the principal challenges presented by modern environmental legislation, particularly the EU Water Framework Directive, a challenge that is exacerbated by the diverse and widespread nature of historical mining. The impact and hazard associated with abandoned mining in one of the UK’s most intensively mined regions, the Almond River Catchment, Scotland, was examined via: 1) a detailed GIS mapping and investigation of historical mining processes in the catchment, 2) mine site discharge sampling, 3) detailed site investigations, 4) geochemical modelling of four mine waste sites and 5) analysis of temporal and spatial river water quality in the catchment. The results are then brought together to produce a catchment scale mine water hazard map. Mapping has identified over 300 mine sites in the catchment including coal, oil shale and ironstone mine wastes and flooded coal and oil shale mines. The historical development of oil shale retort methods has been shown to have an impact on potential hazard. Sampling of discharge waters from the different mining activities, in conjunction with detailed mineralogical analysis and geochemical modelling at the four mine waste sites has characterised the main hazards. Ironstone and pyrite bearing coal mine wastes discharge waters with highly elevated Fe and sulphate concentrations, up to 160mgl-1 and 1900mgl-1 respectively, due to extensive pyrite oxidation and acid generating salt dissolution (principally jarosite). Coal mine wastes show variable mineralogy, due to the diverse nature of coal bearing strata, and discharge waters with variable chemistry. Oil Shale mine wastes are generally depleted in pyrite due to historic processing and discharge low sulphate waters with moderately elevated Fe concentrations, up to 5mgl-1. Flooded coal mines discharge sulphate dominant alkaline waters, due to the availability of carbonate minerals in the mine complex, with elevated Fe concentrations, up to 50mgl-1, while flooded oil shale mines discharge waters with moderately elevated Fe concentrations, up to 4mgl-1, due to lower pyrite content in mine strata and reduced availability of oxygen related to mine abandonment age. Once in the surface water environment iron and sulphate display significant concentration-flow dependence: iron increases at high flows due to the re-suspension of river bed iron precipitates (Fe(OH)3); sulphate concentrations decrease with increased flow as a result of dilution. Further examination of iron and sulphate loading at low flows indicates a close correlation of iron and sulphate with mined areas; cumulative low flow load calculations indicate that coal and oil shale mining regions contribute 0.21 and 0.31 g/s of iron, respectively, to the main Almond tributary. Decreases in iron loading on river sections demonstrate the deposition and diffuse storage of iron within the river channel. This river bed iron is re-suspended with increased flow resulting in significant transport of diffuse iron downstream with load values of up to 50 g/s iron. Based on this hazard classification, a catchment scale mine water hazard map has been developed. The map allows the prioritisation of actions for future mine water management.

Nanosecond repetitively pulsed (NRP) discharges are being increasingly used in various applications, in particular in plasma-assisted combustion and aerodynamic flow control. First, we studied the thermal and hydrodynamic effects of NRP discharges using quantitative Schlieren measurements and numerical analyses in atmospheric pressure air. The time resolved images show the expansion of the heated gas channel starting from as early as 50 ns after the discharge and the shock-wave propagation from about 500 ns. Gas density profiles simulated in 1-D cylindrical coordinates are used to reconstruct numerical Schlieren images for comparison with experimental ones. We propose an original method to determine the initial gas temperature and the fraction of energy transferred into fast gas heating, using a comparison of the contrast profiles obtained from experimental and numerical Schlieren images. The results show that a significant fraction of the electric energy is converted into gas heating within a few tens of ns. The values range from 25 % at a reduced electric field of 164 Td in air at 300 K to about 75 % at 270 Td in air preheated to 1000 K, which supports the fast heating processes via dissociative quenching of N2(B, C) by molecular oxygen. Second, we provide a database to test the kinetic modeling of lean mixture ignition by NRP discharges. We characterize the initial spark radius and the ignition kernel development at pressures up to 10 bar. Comparisons with a conventional igniter show that better results are obtained with NRP discharges in terms of flame propagation speed, especially at high pressure. The flame speed increases by up to 20 % at 10 bar due to the increased wrinkling of the flame front induced by NRP discharges. Finally, we investigate the dynamic response of a flame to actuation by NRP discharges in a 12-kW bluff-body stabilized burner. The results show a significant reduction in flame lift-off height, within 5 ms after applying the NRP discharges. The mechanism is attributed to the entrainment of the OH radicals and heat towards the shear layer of incoming fresh gases. This opens up new applications in the control of combustion instabilities.

Thesis (MScEng (Civil Engineering))--University of Stellenbosch, 2010.<br>ENGLISH ABSTRACT: This investigation focused on the marine components of large direct seawater intake and brine discharge systems for seawater desalination plants, with the main aim to provide an overall design approach for these components. Due to its complexity, an overall and systematic design approach, addressing all the components (feedwater requirements, plant technology, marine structures and environmental issues) is required to ensure an optimum design. A literature review was done on the various desalination technologies, the main components of a seawater desalination plant, as well as the physical, hydraulic, operational and environmental issues regarding seawater extraction facilities, marine pipelines and discharge structures (diffuser). In order to obtain practical input to the development of an overall design approach, information regarding the marine structures of ten of the largest existing seawater desalination plants throughout the world were obtained and compared with each other and the available technologies. By way of example, the recently designed marine components of a new seawater reverse osmosis desalination plant in Namibia were reviewed and, as part of this thesis, alternative conceptual concepts which will include two additional components (sump and brine reservoir) were designed. The alternative design was compared with the actual design in order to determine the feasibility of the alternative in terms of operation and cost and subsequently provide input to the overall design recommendations. Furthermore, from the literature review it seems that there are still significant uncertainties regarding the required performance of a brine (dense) outfall and this required more attention in terms of environmental and hydraulic performance. Based on the Namibian plant, the diffuser configuration was analysed in terms of its hydraulic and environmental performance and subsequently some general guidance with specific respect to a brine diffuser was developed, which in turn formed part of the overall design approach for the marine components. Finally, the design approach for seawater intake structures, brine outfalls and the connecting marine pipelines is provided in the form of flow diagrams.<br>AFRIKAANSE OPSOMMING: Hierdie ondersoek handel oor die mariene komponente van groot en direkte toevoer van seewater en die sout-uitvloeisisteme van ontsoutingsaanlegte van seewater. Die doel is om ‘n oorsigtelike ontwerpbenadering vir hierdie component te verskaf. As gevolg van die kompleksiteit, is ‘n oorsigtelike en sistimatiese benadering, wat al die komponente (vereistes vir toevoerwater, tehnologie by die aanleg, mariene omstandighede en omgewingsfaktore) in ag neem noodsaaklik om die beste ontwerp te verseker. ‘n Literêre oorsig is gedoen ten opsigte van die tegnologie van verskeie ontsoutingsmetodes, die hoofkomponente van ‘n seewater-ontsoutingsaanleg, asook die fisiese, hidrouliese, operasionele en omgewingskwessies rakende die fasiliteite om die seewater te onttrek, die mariene pyplyne en die strukture vir die afvloei. Ten einde die optimum ontwerp te ontwikkel, is inligting oor die tegnologie en strukture van tien van die grootste bestaande onsoutingsaanlegte in die wêreld bekom, bestudeer en vergelyk Hulle is met mekaar vergelyk, asook met beskikbare tegnologie. As ‘n voorbeeld is die nuut ontwerpte mariene komponente van die nuwe ontsoutingsaanleg in Namibië, waar ontsouting d.m.v. omgekeerde osmose gedoen word ondersoek en as deel van hierdie tesis, is ‘n alternatiewe konsep, wat twee bykomende komponente – ‘n opvangput en reservoir vir die afloop – ontwerp. Hierdie alternatiewe ontwerp is met die werklike aanleg vergelyk om die uitvoerbaarheid van die onderneming en die koste daaraan verbonde te toets. Dit is gebruik as aanbeveling vir die oorhoofse ontwerp. Uit die literêre oorsig blyk dit dar daar nog groot onsekerheid is oor die vereistes van die (digte) waterafloop en dat meer aandag aan die omgewings- en hidrouliese aspekte gegee moet word. Met die Namibiese aanleg as voorbeeld, is die struktuur van die spreiers t.o.v. hidrouliese werkverrigting en die omgewing ontleed. Voortspruitend daaruit is algemene riglyne vir ‘n spesifieke spreier vir afloopwater ontwikkel, wat op sy beurt weer deel vorm van die oorhoofse ontwerp vir mariene komponente. Laastens is die ontwerp vir die strukture vir seewater-invloei, die afloopwater en die mariene verbindingspyplyne as vloeidigramme aangetoon.

Thesis (M.S.)--West Virginia University, 2005.<br>Title from document title page. Document formatted into pages; contains viii, 70 p. : ill., maps. Vita. Includes abstract. Includes bibliographical references.

Ocean Thermal Energy Conversion (OTEC) is a renewable energy technology that has to overcome several key challenges before achieving its ultimate goal of producing baseload power on a commercial scale. The economic challenge of deploying an OTEC plant remains the biggest barrier to implementation. Although small OTEC demonstration plants and recent advances in subsystem technologies have proven OTEC’s technical merits, the process still lacks the crucial operational data required to justify investments in large commercial OTEC plants on the order of 50-100 megawatts of net electrical power (MWe-net). A pre-commercial pilot plant on the order of 5-10 MWe-net is required for an OTEC market to evolve. In addition to the economic challenge,OTEC plants have potential for adverse environmental impacts from redistribution of nutrients and residual chemicals in the discharge plume. Although long-term operational records are not available for commercial sizeOTEC plants, synergistic operational data can be leveraged from the desalination industry to improve the potential for OTEC commercialization. Large capacity desalination plants primarily use membranes or thermal evaporator tubes to transform enormous amounts of seawater into freshwater. Thermal desalination plants in particular possess many of the same technical, economic, and environmental traits as a commercial scale OTEC plant. Substantial long-term economic data and environmental impact results are now widely available since commercial desalination began in the 1950s. Analysis of this data indicates that the evolution of the desalination industry could be akin to the potential future advancement of OTEC. Furthermore, certain scenarios exist where a combined OTEC-desalination plant provides a new opportunity for commercial plants. This paper seeks to utilize operational data from the desalination industry as a progressive approach towards OTEC commercialization.

Orientador: Alexandre Nunes Ponezi<br>Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo<br>Made available in DSpace on 2018-08-24T03:39:40Z (GMT). No. of bitstreams: 1 Carvalho_AdrianaMoreirade_M.pdf: 1845215 bytes, checksum: 959617b3b0d7f3705be1207e704dc50d (MD5) Previous issue date: 2013<br>Resumo: Atualmente a preocupação em relação à qualidade das águas consumidas, seja para hidropinia, recreação ou para usos terapêuticos é fato. As águas termais usadas para fins terapêuticos não poderiam deixar de estar nesse contexto. Na cidade de Poços de Caldas-MG, a população dispõe de dois Fontanários de águas termais sulfurosas de livre acesso para usos diversos, inclusive para ingerir. Desde que foram captadas em 1882, o sistema permanece com as mesmas características estruturais de quando foram implantadas. Além disso, a cidade cresceu e invadiu as áreas próximas às nascentes dessas águas, oferecendo riscos devido às ações antrópicas. Esse trabalho analisou a qualidade das águas termais sulfurosas distribuídas no Fontanário Pedro Botelho, localizado nas Thermas Antônio Carlos, e no Fontanário dos Macacos, situado no Balneário Mário Mourão, fazendo uma avaliação das águas segundo os padrões microbiológicos, bacteriológicos, físico-químicos, composição química e de radionuclídeos, durante um período de 12 meses e comparou com as legislações vigentes. Praticamente, todos os padrões estão dentro dos parâmetros de qualidade, exceto para os elementos denominados fluoreto e sódio que se encontram com valores acima do permitido pela legislação, que estipula limites para águas utilizadas para consumo humano, embora os usos a que se destinam as águas termais sulfurosas sejam para fins terapêuticos. Quanto aos valores altos de fluoreto foram detectados tanto no ponto do Fontanário Pedro Botelho quanto no Fontanário dos Macacos. Estas alterações no valor deste elemento estão relacionadas com uma incorporação natural do fluoreto às águas subterrâneas, devido à lixiviação das rochas fluoritas alcalinas, abundantes nessa região. O excesso de fluoreto nas águas consumidas podem causar fluorose dentária que se caracteriza por apresentar um escurecimento do esmalte dos dentes ou a fluorose óssea que se manifesta causando um enfraquecimento do esqueleto. Quanto ao valor de sódio, que ultrapassou os limites permissíveis pela legislação Portaria n. 2914/11 em média de 20 a 25%, nos dois Fontanários, pode-se relacionar a presença deste elemento nas águas termais sulfurosas à geologia do local. O sódio em excesso e se ingerido com frequência pode ser prejudicial para indivíduos hipertensos<br>Abstract: Currently the concern about the quality of water consumed, either for hidropinia, recreation or a therapeutic use is fact. The thermal waters used for therapeutic purposes could not help but be in that context. In the city of Poços de Caldas, Minas Gerais, the population has two Fountains of sulphurous hot springs with free access for various uses, including drinking. Since they were captured in 1882, the system remains the same structural characteristics when implemented. In addition, the city grew and invaded the waters near the headwaters of these areas, offering risks due to human actions. This study examined the quality of the sulphurous hot springs distributed in Fountains Pedro Botelho, located in thermas Antônio Carlos, and Fountain of the Macacos, located in Balneario Mario Mourão, with an evaluation of the water according to the microbiological, bacteriological, physical and chemical composition standards chemicals and radionuclides for a period of 12 months and compared with the existing laws. Virtually all standards are within the quality parameters, except for the elements called fluoride and sodium which are values above those permitted by law, which stipulates limits for waters used for human consumption, although the uses for which the waters are intended thermal sulphurous be for therapeutic purposes. As for the high values of fluoride were detected in both point Fountain Pedro Botelho as the Fountain of the Macacos. These changes in the value of this element are related to a natural incorporation of fluoride to groundwater due to leaching of alkaline, abundant fluorite rocks in this region. Excess fluoride in water consumed can cause dental fluorosis which is characterized by having a darkening of tooth enamel or skeletal fluorosis which manifests a weakening of the skeleton. As for the sodium value that exceeded allowable limits by legislation Ordinance no. 2914/11 on average from 20 to 25 % in the two Fountains, one can relate the presence of sulfur element in the thermal water the local geology. The excess sodium ingested and often can be harmful for hypertensive patients<br>Mestrado<br>Saneamento e Ambiente<br>Mestra em Engenharia Civil

In this work new novel cathode materials such as transition-metal sulfides, chlorides or fluorides were investigated and studied for their use in lithium ion thermal batteries. All cathodes were synthesized by a solid state reaction in sealed quartz tubes with a duration of firing for 1 week at high temperatures ( > 500 °C). All structures of compounds were probed by powder X-ray diffraction and the morphology and shape of crystallites of cathodes were characterized by scanning electron microscopy. The electrochemical properties of the batteries were investigated by galvanostatic discharge and galvanostatic intermittent titration technique at high temperatures (> 400 °C). All the batteries used as an anode Li₁₃Si₄, as an electrolyte LiCl-KCl eutectic and as separator MgO. All the products of the discharge mechanism were confirmed using powder X-ray diffraction and EDX analysis. CoNi₂S₄ and NiCo₂S₄ exhibit two voltage plateaux vs Li₁₃Si₄ at 500 °C, one at around 1.75 V and the second at 1.50 V. Capacities of 350 and 290 mA h g⁻¹ were achieved, respectively. NiS, Co₃S₄ and Co₉S₈ were confirmed as the products of discharge mechanism. ZrS₃ exhibits a single flat voltage plateau of 1.70 V at a current density of 11 mA/cm² and a capacity of 357 mA h g⁻¹, at 500 °C was obtained. A new material, LiZr₂S₄, was identified as the product of the electrochemical process, which can be indexed to a = 10.452(8) Å cubic unit cell. KNiCl₃ was tested at different current densities from 15 mA/cm² to 75 mA/cm² and a high cell voltage, with a capacity of 262 mA h g⁻¹ was achieved at 425 °C. Ni metal, KCl and LiCl were confirmed as the products of the discharge mechanism. Li₂MnCl₄ was tested at the same current densities as KNiCl₃ at 400 °C and a capacity of 254 mA h g⁻¹ was achieved. Mn metal and LiCl were confirmed as the products after discharge. Li₆VCl₈ has a capacity of 145 mA h g⁻¹ and a flat voltage plateau of 1.80 V at 500 °C. NiCl₂ has also a capacity of 360 mA h g⁻¹ and a high voltage profile of 2.25 V at 500 °C. CoCl₂ exhibits a lower capacity of 332 mA h g⁻¹ and lower voltage profile compared to NiCl₂ at 500 °C. CuF₂ and PbF₂ were tested at 500 °C. PbF₂ exhibits a single flat voltage plateau of 1.25 V and a capacity of 260 mA h g⁻¹ was obtained. CuF₂ has a high voltage profile but a voltage plateau could not be obtained.

L'objectif de ces travaux était d'étudier l'interaction entre des plasmas froids à pression atmosphérique et des milieux biologiques en vue d'application de ce type de technologie au secteur biomédical.Dans un premier temps, des sources plasma ont été conçues, réalisées et caractérisées. Il s'agissait de réacteurs mettant en œuvre des décharges sur barrière diélectrique dans différents gaz en flux (air synthétique, argon, avec ou sans apport de vapeur d'eau). L'utilisation de l'argon a permis de sélectionner des conditions dans lesquelles le plasma demeurait confiné dans la zone inter-électrodes (humidité relative supérieure à 95% à température ambiante) ou au contraire se propageait soit en atmosphère libre, soit guidé dans un tube isolant dans lequel circulait le gaz (argon sec). Dans ce dernier cas, le phénomène de propagation a été examiné par des mesures électriques résolues dans le temps et les résultats ont été discutés à l'aide des travaux antérieurs disponibles dans la littérature. Le choix de l'air comme gaz plasmagène a également été considéré en raison des contraintes d'application ne permettant pas systématiquement l'utilisation d'un autre gaz.Deux études spécifiques ont été conduites, l'une susceptible de trouver des applications dans le domaine de la « plasma médecine », l'autre dans le domaine de la lutte contre les épidémies virales.Dans ce dernier cas, les travaux ont porté sur l'inactivation de virus bactériens, ou bactériophages, infectant Escherichia coli. Il s'agissait du phage T4, phage à ADN double brin, et du phage MS2, phage à ARN simple brin. Les suspensions de phages ont été diluées dans différentes solutions tampons et déposées sur un substrat de papier hydrosoluble pour être exposées aux différents traitements par plasma froid. L'utilisation originale de ce substrat a permis de résoudre le problème difficile de la récupération des particules de phage après traitement. Ce substrat correspond également à une situation d'application défavorable à ce type de traitement (surface complexe avec diffusion en volume de la suspension, au contraire d'une surface lisse non-adsorbante telle qu'une lamelle de verre), conduisant à obtenir des résultats plus réalistes et transposables à une application réelle. L'inactivation des phages a été quantifiée par comptage de plages de lyse sur culture de E. coli. Ainsi, des taux d'inactivation compris entre 0,66 log/min et 2 log/min ont été mesurés suivant le type de phage, la nature de la solution tampon et le type de traitement. L'influence de la température imposée au substrat a également été examinée.Dans le cadre de l'application en plasma médecine, des cellules d'adénocarcinome humain (cancer du poumon) provenant de cinq patients ont été traitées in-vitro à l'aide du réacteur à barrière diélectrique dans deux conditions de fonctionnement déterminées par la composition du gaz d'alimentation : jet de plasma avec de l'argon sec et source d'espèces oxydantes avec de l'argon saturé en vapeur d'eau à température ambiante. A l'issue d'une exposition de 5 minutes au traitement par décharge d'argon humide, 65% des cellules étaient dans un état apoptotique/nécrotique. Pour le traitement par plasma d'argon sec, les tests globaux de prolifération et d'apoptose n'ont pas montré une grande efficacité. Toutefois, le jet de plasma d'argon sec a présenté un effet rapide et localisé sur les cellules cancéreuses, induisant une inhibition de la capacité des cellules à proliférer et à migrer. Ces deux conditions de fonctionnement sont d'intérêt pour l'application clinique, permettant d'avoir un seul dispositif plasma capable de délivrer un traitement très localisé des cellules (jet plasma) ou de transférer des espèces oxydantes sur une plus grande surface conduisant à des mécanismes d'apoptose (décharge d'argon humide)<br>The objective of this work was to study the interaction between non-thermal plasmas at atmospheric pressure and biological media in perspective of the application of this type of technology to the biomedical sector.In a first step, plasma sources were designed, realized, and characterized. These reactors implement dielectric barrier discharges in various gases in flow (synthetic air, argon, with or without water vapor admixture). The use of argon allowed the selection of conditions in which the plasma remained confined in the inter-electrode zone (relative humidity higher than 95% at room temperature) or on the contrary propagated either in free atmosphere or guided in an insulating tube in which the gas was flowing (dry argon). In the latter case, the propagation phenomenon was examined by time-resolved electrical measurements and the results were discussed with the help of previous works available in the literature. The choice of air as reactor feed-gas was also considered because of the application constraints that do not systematically allow the use of another gas.Two specific studies were conducted, one likely to find applications in the field of "plasma medicine", the other in the field of control of viral epidemics.In the latter case, the work focused on the inactivation of bacterial viruses, bacteriophages, infecting Escherichia coli. These were phage T4, a double-stranded DNA phage, and phage MS2, a single-stranded RNA phage. The phage suspensions were diluted in different buffer solutions and deposited on a water-soluble paper substrate to be exposed to different non-thermal plasma treatments. The original use of this substrate solved the difficult problem of phage particle recovery after treatment. This substrate also corresponds to an unfavorable application situation for this type of treatment (complex surface with volume diffusion of the suspension, as opposed to a smooth non-adsorbent surface such as a glass slide), leading to more realistic results that can be transposed to a real application. Phage inactivation was quantified by counting lysis plaques on E. coli culture. Thus, inactivation rates ranging from 0.66 log/min to 2 log/min were measured depending on the type of phage, the nature of the buffer solution and the type of treatment. The influence of the temperature imposed on the substrate was also examined.For the plasma medicine application, human adenocarcinoma cells (lung cancer) from five patients were treated in-vitro using the dielectric barrier reactor under two operating conditions determined by the composition of the feed-gas: plasma jet with dry argon and reactive oxidizing species (ROS) source with argon saturated with water vapor at room temperature. After a 5-minute exposure to the humid argon discharge treatment, 65% of the cells were in an apoptotic/necrotic state. For the dry argon plasma treatment, the overall proliferation and apoptosis assays did not show much efficacy. However, the dry argon plasma jet exhibited a rapid and localized effect on the cancer cells, inducing inhibition of the cells' ability to proliferate and migrate. These two operating conditions are of interest for clinical application, allowing to have a single plasma device able to deliver a very localized treatment of cells (plasma jet) or to transfer ROS on a larger surface leading to apoptosis mechanisms (humid argon discharge)

High Electron Mobility Transistors (HEMTs) are finding wide applications in many areas, including microwave power amplifiers, radars, communication and conversion fields. The high mobility, due to the reduction of scattering phenomena, and the high carrier density, due to the confinement of electrons in the so called 2DEG, allowed the achievement of a high current density and low channel resistance, thus making these devices very suitable for high frequency applications. HEMTs are usually based on III-V materials, especially GaAs and GaN technology, as a consequence of their electrical properties. In the last years gallium nitride has become one of the most interesting and suitable material. The high direct energy gap led to better performances especially in optoelectronic devices such as Light emitting diodes, lasers and detectors. Furthermore, the high carrier saturation velocity and the high mobility demonstrated high performances in devices aimed at high frequency, such as HEMTs. Finally the high electric field breakdown and Johnson’s figure of merit suggest its use for devices with high power requirements, thus overcoming in many areas gallium arsenide technology. For many applications, such as MMIC (monolithic microwave integrated circuits) structures, gallium arsenide is preferable, mainly as a consequence of excellent charge transport properties and low loss at microwave and millimetre-wave frequencies. Furthermore, especially for commercial purposes, gallium arsenide is more used due to the well-established technology. Although the significant intrinsic properties, both gallium arsenide and gallium nitride HEMT technology are still affected by reliability issues which limit their performances in common applications. The purpose of this thesis is to study reliability topics which limit HEMT technology on the basis of materials used, namely GaAs, GaN, InAlN, in order to define corresponding limits and performances. With the aim of providing for a more complete perspective the analysis will focus not only on discrete transistors but it will be extended also on complete structures such as power amplifiers. Within this work we present a detailed study of two main degradation mechanisms which still affect GaAs technology and limit its performances both in discrete pHEMTs and in commercial complete structures: thermal degradation and electrostatic discharge failure. Thermal degradation analysis has been firstly studied on discrete structures, namely pseudomorphic HEMTs. A first purpose is to define main failure mechanisms and modes by means of a long term thermal stress with no bias applied. Several analysis (DC, pulsed, end resistances and barrier height evaluation) has been proposed to monitor devices behaviour. Degradation appears to be non-monotonic, i.e. drain current first decreases, then increases again, following the corresponding shifts in the threshold voltage. Although the initial decrease of drain current could be attributed to gate metal interdiffusion, or "gate sinking", leading to a positive shift of threshold voltage, it is accompanied by a variation of the maximum value of transconductance and an increase of end resistances, that suggest a concurrent degradation of ohmic contacts. A third mechanism, represented by the Schottky barrier height, counteracts the effect of gate interdiffusion and eventually prevails, leading to an opposite shift of the threshold voltage. Devices used for high power applications can reach high junction temperatures as a consequence of the power dissipation, demonstrating the importance of accurately defining the thermal resistance, i.e. the channel temperature variation as a function of power dissipated. A second purpose of this chapter is to provide for a detailed description of different techniques (namely DC, pulsed and infrared thermal camera) to estimate channel temperature of HEMTs and to present a critical comparison among them. Differently from DC and pulsed evaluation, analysis with IR thermal camera strongly underestimates the results. With the aim of understanding the impact of inaccuracies on a high frequency application the analysis has been extended to a four stage MMIC power amplifier. The strong underestimation of IR method has been confirmed; furthermore the thermal interaction among different stages and its impact on the structure has been studied. By means of a deep analysis of thermal resistance a HTOL test has been proposed on power amplifiers, submitting the devices both to an electrical and thermal stress and confirming that no significant effect is noticed if a junction temperature lower or equal to 250°C is reached. Comparison between VTH shift in HTOL and thermal stress suggests that the junction temperature has been slightly underestimated. Electrostatic discharge robustness has been studied on a four stage MMIC power amplifier based on GaAs pHEMT technology used in commercial point to point microwave systems. The structure is characterized by a ESD protection circuit mainly defined by Schottky diodes protection structures at the gate terminals and resonant circuit protection structure at the RF input and output pads. Robustness has been analysed with a 100ns TDR-TLP. Results have been confirmed with HBM and MM tests. No failures are observed in the RF-IN, RF-OUT and Drain connections vs. GND up to ±2 kV and ±200 V HBM and MM respectively. RF pads failed with TLP analysis at about 6.5-7A, resulting in an open circuit at the inductor and a short at the capacitor of the resonant structure. Gate connections fail in correspondence of the negative HBM pre-charge value starting from -1.0 kV; MM stresses lead to the failure of the Gate connections from -50 V. Failures are due to the damage of anti-parallel Schottky diodes acting as ESD protection structures. The auxiliary connections reveal to be the most sensitive I/Os of the entire PA, failing at 250 V and 25 V, respectively HBM and MM, due to the failure of integrated resistors. A second part of the thesis mainly focuses on AlGaN/GaN devices. One of the main aspects which limit devices RF and power performances is the so-called current collapse and trapping effects. Therefore a detailed analysis has been proposed on devices characterized by a different iron doping in the buffer layer aimed at preventing parasitic effects and punch through phenomenon. The aim is to define a correlation between the trapping behaviour and iron doping in the buffer layer. A further purpose is to study the correlation between several degradation phenomena when a reliability stress is imposed, both in terms of DC characterization, trapping effects and light emission analysis. A comparison of the correlation between different degradation phenomena in devices with several iron doping quantities is finally proposed. Results are consistent with further investigations reported in literature which correlate the use of iron doping to a trap level with activation energy of 0.57-0.7eV. The analysis firstly demonstrates that iron doping determines a measurable current collapse, which is related to the presence of a trap (T1) located in the buffer with time constant of 3.2ms at T=40°C. Trapping location is consistent with the amplitude significant increase with Fe-concentration in the buffer. Furthermore trap T1 reveals a lower activation energy in devices with no iron doping. The amplitude of trap T1 in devices with different structures and comparison with works reported in literature suggest that the trap is due to an intrinsic defect in the buffer layer characteristic of GaN, although its concentration strongly depends on buffer doping quantity. Results of current transients with different filling pulses applied suggest that trapping is due to line defects or point defects clustering around dislocations. A second trap, T2, is detected. According to comparison of devices with different iron doping and comparison with gm(f) analysis we can suppose that T2, characterized by a time constant of 0.25s at T=40°C, is probably located in the AlGaN layer. Results of an electrical stress applied to the gate terminal of Fe doped devices indicate that the main consequences of the stress experiments are (i) an increase in the leakage gate current, which is strongly correlated to light emission and – beyond the critical voltage – to an increase in the current collapse and (ii) the increase in the transient signal associated with the pre-existing trap levels, without the generation of new traps. Discussion about different results related to the Fe doping buffer layer demonstrates that, when submitted to step-stress, all the devices show a significant and permanent increase in gate leakage current. Furthermore stress induces also an increase in current collapse, which is not correlated to the generation of new trap levels but originates from the increase in the signal associated with the pre-existing trap levels T1 and T2. The change in the signal of T2 (which is supposed to be located in the AlGaN barrier) may be due to an increase in the concentration of a defect (T2); the change of T1, (probably located in the buffer layer) can be explained by the generation of defect-related conductive paths between the gate and the channel which enhance transfer electrons toward the trap states. In the last part new materials to improve GaN technology performances are studied. InAlN/GaN structures are becoming very important as a consequence of the higher carrier density in the 2DEG and the possible achievement of a lattice matched structure, thus significantly improving device electrical and thermal stability. Further improvements, especially at the contacts, will be presented within this thesis. A first analysis consists of the use of a different material for the Schottky gate contact. A comparison of InAlN/GaN HEMTs with analogous structure but different gate, namely Mo/Au and Ni/Pt/Au, is studied. Despite no significant variation is noticed during DC analysis, pulsed evaluation demonstrates that the use of a Mo/Au gate contact leads to an improvement of trapping characteristics, mainly due to the process used for contact deposition. By means of a three terminals step stress it is finally proved that Mo/Au does not significantly affect device stability. A second analysis consists of the definition of a recess before the deposition of ohmic contacts to reduce parasitic resistances. The comparison is proposed for two different wafer, characterized by a similar but not analogous structure and different Carbon doping quantity to avoid parasitic leakage current. DC analysis shows that a significant variation is noticed in IDSS value, showing that a lower value corresponds to structures with recess at the ohmic contacts. This aspect is mainly due to the fact that a lower on resistance measured in linear zone is not obtained. Pulsed analysis states a high current collapse value with no significant correlation with device structure or presence of recess at the ohmic contacts. Drain current transient reveals two main traps, labelled T1 and T2. Activation energy, differently from the cross section value, is not influenced by device structure or by recess at the ohmic contacs. On the basis of drain current transients, gm(f) analysis and previous works reported in literature we can speculate that trap T2 is located in the buffer layer, differently from trap T1 which is probably in the AlGaN layer. Filling time measurements indicate that both the traps are mainly due to line defects.<br>High Electron Mobility Transistors (HEMTs) sono utilizzati in molte applicazioni, tra le quali microwave power amplifiers, radars, applicazioni per telecomunicazioni e potenza. L’alta mobilità, dettata dalla riduzione dei fenomeni di scattering, e l’alta densità di portatori, dettata dal confinamento degli elettroni in una buca quantica triangolare (2DEG), hanno permesso il raggiungimento sia di un’alta densità di corrente, sia di una bassa resistenza di canale, rendendo questi dispositivi particolarmente indicati per applicazioni che richiedono alta frequenza. Gli HEMT sono in genere composti da materiali III-V, nello specifico arseniuro di gallio (GaAs) e in nitruro di gallio (GaN), come conseguenza delle loro proprietà a livello elettrico. Negli ultimi anni il nitruro di gallio è diventato uno tra i materiali più interessanti e utilizzati. L’alto energy gap diretto permette di raggiungere prestazioni molto migliori in particolare nei dispositivi optoelettronici, come Light emitting diodes, lasers and detectors. Inoltre l’alta velocità di saturazione dei portatori e l’alta mobilità hanno condotto ad alte prestazioni anche in dispositivi che lavorano ad alte frequenze, come gli HEMT. Infine, l’alto valore di campo elettrico di breakdown e la Johnson’s figure of merit ne permettono l’utilizzo in dispositivi per applicazioni di potenza, superando dunque in molti ambiti l’arseniuro di gallio. Tuttavia, per molte applicazioni, quali ad esempio strutture MMIC (monolithic microwave integrated circuits), si preferisce ricorrere all’arseniuro di gallio, principalmente per le eccellenti proprietà di trasporto di carica e le perdite minori a frequenze corrispondenti alle microonde. Inoltre, in particolare per scopi commerciali, l’arseniuro di gallio rimane un’ottima soluzione in quanto tecnologia molto stabile in termini di affidabilità. Nonostante le significative proprietà intrinseche, gli HEMT sia in arseniuro di gallio sia in nitruro di gallio sono ancora caratterizzati da numerosi problemi in termini di affidabilità che limitano in modo significativo le loro prestazioni nella maggior parte delle applicazioni. Lo scopo di questa tesi è dunque di studiare alcuni aspetti peculiari che limitano la tecnologia HEMT. Si è voluto proporre un approccio basato sui materiali utilizzati, principalmente GaAs, GaN, InAlN, per poter definire limiti e prestazioni corrispondenti prestando particolare attenzione al materiale considerato. La scelta di voler proporre una prospettiva maggiormente completa ha condotto a non focalizzare l’analisi solo su transistor HEMT discreti ma anche su strutture complete come amplificatori di potenza. In questo lavoro si presenta uno studio dettagliato di due meccanismi di degrado che influenzano ancora la tecnologia in arseniuro di gallio, limitandone le prestazioni sia in dispositivi discreti che in strutture complete commerciali: degrado termico e guasti per scariche elettrostatiche. Il degrado termico è stato innanzitutto studiato su strutture discrete, ovvero su HEMT pseudomorfici. Un primo obiettivo consiste nel definire i principali meccanismi e modi di degrado in seguito ad uno stress termico accelerato senza polarizzazione. Per monitorare il comportamento dei dispositivi numerose analisi sono state proposte, ovvero caratterizzazione DC, impulsata, misura delle end resistances e calcolo dell’altezza di barriera. Durante lo stress il degrado sembra essere non monotono, in quanto la corrente di drain inizialmente cala per poi crescere nuovamente, in modo coerente con gli spostamenti corrispondenti della tensione di soglia. Nonostante la variazione iniziale di corrente si possa attribuire a interdiffusione metallurgica (gate sinking), dimostrata anche da uno shift positivo della tensione di soglia, tale fenomeno è accompagnato anche da un degrado ai contatti ohmici, come dimostrato dalla variazione del picco della transconduttanza e dall’aumento delle corrispondenti resistenze parassite (end resistances). Un terzo meccanismo, descritto dalla diminuzione dell’altezza di barriera del diodo schottky, produce un effetto opposto all’interdiffusione metallurgica, in taluni casi anche prevalendo e comportando uno shift negativo della tensione di soglia. I dispositivi usati per applicazioni che richiedono alta potenza possono raggiungere significative temperature di giunzione come conseguenza della dissipazione in potenza, definendo così l’importanza di una corretta definizione della resistenza termica, i.e. la variazione della temperatura di giunzione in funzione della potenza dissipata. Il secondo obiettivo è dunque quello di fornire una descrizione dettagliata di diverse tecniche (DC, impulsata, infrarossi) per stimare la temperatura di canale in un HEMT e proporre, di conseguenza, un confronto tra di esse esplicitando anche i corrispondenti vantaggi e svantaggi. A differenza dell’analisi con misure DC o impulsate, l’analisi con camera a infrarossi sottostima i risultati. Per riuscire a comprendere l’effetto delle imprecisioni in un’applicazione ad alta frequenza l’analisi è stata estesa ad un amplificatore di potenza sviluppato con struttura MMIC. Si conferma la significativa sottostima del metodo infrarossi. È inoltre possibile definire il fenomeno d’interazione termica tra diversi stadi e la sua influenza nella struttura analizzata. Attraverso un’analisi dettagliata della resistenza termica è stato condotto un test HTOL sugli amplificatori di potenza, sottoponendo questi ultimi sia ad uno stress di tipo elettrico che di tipo termico e confermando il non significativo degrado quando una temperatura di giunzione inferiore a 250°C è imposta. Il confronto della variazione di tensione di soglia nel test HTOL e nel test puramente termico suggerisce che i valori di resistenza termica siano stati leggermente sottostimati. La robustezza verso le scariche elettrostatiche è stata studiata in un amplificatore di potenza con struttura MMIC basato su una tecnologia in HEMT pseudomorfici in arseniuro di gallio, usato a livello commerciale per sistemi microonde point to point. La struttura è caratterizzata da un circuito di protezione ESD principalmente costituito da diodi Schottky in corrispondenza dei terminali di gate e circuiti risonanti agli ingressi RF. La robustezza è stata analizzata con un impulso TDR-TLP di 100ns. I risultati sono stati confermati sia da test HBM che da test MM. Non sono stati riportati guasti nelle connessioni RF e in corrispondenza dei terminali di drain fino ad una tensione di ±2 kV e ±200 V misurata rispettivamente in HBM e MM. I pad RF si rompono in corrispondenza di una corrente misurata con il TLP di 6.5-7A, risultando in un lato aperto in corrispondenza dell’induttore e in un corto circuito in corrispondenza del condensatore, entrambi appartenenti al circuito risonante di protezione. Le connessioni di gate degradano quando una tensione HBM negativa di precarica di -1kV è applicata; risultati coerenti sono riportati dalla misura MM, dimostrando degrado ad una tensione negativa di precarica pari a -75V. Il guasto è riscontrato in corrispondenza dei diodi Schottky posti in anti parallelo come struttura di protezione ESD. Le connessioni ausiliarie per incrementare le prestazioni del dynamic range risultano essere le più sensibili, con una tensione di rottura pari a ±500V e ±50V misurate rispettivamente in HBM e MM, in seguito alla rottura di resistori integrati. La seconda parte della tesi discute i meccanismi di trapping in dispositivi AlGaN/GaN. I fenomeni di trapping, e il conseguente current collapse, risultano essere tra gli aspetti che maggiormente limitano le prestazioni RF e di potenza nei dispositivi HEMT. L’analisi è stata effettuata su dispositivi con un differente drogaggio intenzionale di Ferro nel buffer layer. Tale drogaggio è in genere utilizzato per limitare i fenomeni parassiti e di punch through. Lo scopo primo dell’analisi è definire una correlazione tra i meccanismi di trapping e l’entità di drograggio nel buffer layer. In secondo luogo si è voluto studiare e proporre una correlazione tra differenti fenomeni di degrado nel momento in cui il dispositivo è sottoposto ad uno stress di affidabilità, in termini di caratterizzazione DC, effetti di trapping e analisi di elettroluminescenza. Un confronto di tale correlazione in dispositivi con differente quantità di ferro nel buffer layer è infine proposta. I risultati ottenuti sono coerenti con studi proposti in letteratura, che correlano l’uso di drogaggio in Ferro con una trappola con energia di attivazione pari a 0.57-0.7eV. L’analisi dimostra innanzitutto che il drogaggio in ferro determina un significativo current collapse, correlato con la presenza di una trappola (T1) presumibilmente localizzata nel buffer layer e caratterizzata da una costante di tempo pari a 3.2ms a T=40°C. La posizione della trappola è coerente con l’aumento dell’ampiezza corrispondente al variare della concentrazione di ferro nel buffer. Inoltre la trappola T1 mostra un’attivazione termica molto inferiore (0.2eV) nei dispositivi senza buffer drogato. L’ampiezza della trappola T1 in dispositivi con diversa struttura e il confronto con lavoro precedentemente esposti in letteratura suggerisce che la trappola sia dovuta ad un difetto intrinseco nel buffer layer tipico del GaN; tuttavia la sua concentrazione varia significativamente con la presenza di ferro. L’analisi dei transienti di corrente al variare del tempo di intrappolamento ci permette di ipotizzare che l’intrappolamento non sia dovuto a difetti puntuali o comunque sia dovuta a difetti puntuali ammassati vicino alle dislocazioni. Una seconda trappola, T2, è evidenziata. L’analisi delle trappola in dispositivi con differente drogaggio e il confronto con analisi gm(f) ci permette di supporre che tale trappola, con una costante di tempo di 0.25s a T=40°C, sia situata nello strato AlGaN. I risultati ottenuti da uno stress elettrico imposto al terminale di gate in dispositivi drogati con ferro ne definiscono gli effetti principali: (i) aumento della corrente di leakage, fortemente correlato con l’aumento di hot spot nell’elettroluminescenza e, superata la tensione critica, con un aumento del current collapse. (ii) aumento del segnale associato a segnali preesistenti senza generazione di nuovi stati trappola. L’analisi, estesa a dispositivi con differente o nullo drogaggio in ferro dimostra che, se sottomessi a uno stress di affidabilità, tutti i dispositivi mostrano una variazione della corrente di leakage. Lo stress comporta inoltre un aumento del current collaspe, non correlato alla generazione di nuovi stati trappola bensì all’aumento del segnale associato alle trappole preesistenti, chiamate T1 e T2. La variazione dell’ampiezza di segnale in T2, che si presume essere nell’AlGaN, può essere connessa ad un aumento della concentrazione del difetto; la variazione di T1, che al contrario si presume essere nel buffer layer, può essere chiarita con la generazione di difetti connessi a cammini parassiti conduttivi tra il gate e il canale, generati a causa dello stress, che favoriscono il trasferimento di elettroni verso gli stati trappola. Nell’ultima sezione si studiano nuovi materiali per migliorare le prestazioni della tecnologia GaN. Le strutture InAlN/GaN stanno diventando importanti grazie all’alta densità di portatori nel 2DEG e alla possibilità di ottenere una struttura lattice matched, migliorandone dunque la stabilità elettrica e termica. In questa tesi nuove strutture, in particolare ai contatti, sono discusse. Una prima analisi consiste nell’uso di un differente materiale per il contatto Schottky. Si propone un confronto tra HEMT InAlN/GaN con struttura identica ma differente gate, nello specifico Mo/Au e Ni/Pt/Au. Nonostante non si noti alcuna variazione significativa nell’analisi DC, la valutazione dei fenomeni di trapping mostra che l’uso di un contatto in Mo/Au mostra un miglioramento significativo nelle caratteristiche di trapping, principalmente dettata dal processo usato per la deposizione dei contatti. L’uso di un contatto in Mo/Au, come dimostrato dai risultati di uno stress in OFF state, non influenza la stabilità del dispositivo. Una seconda analisi presenta una struttura in cui è effettuato un recesso prima della deposizione dei contatti ohmici per ridurre le resistenze parassite. Si propone un confronto tra due wafer, caratterizzati da una struttura simile e diversa quantità di drogaggio in carbonio al loro interno per limitare il fenomeno del punch through. L’analisi DC mostra una significativa variazione nel valore , mostrando che un valore minore di IDSS corrisponde a strutture con recesso ai contatti ohmici. Questo effetto è dovuto al non raggiungimento di una resistenza in zona lineare minore. L’analisi impulsata dimostra un alto valore di current collapse senza correlazione con struttura del dispositivo o presenza di recesso ai contatti ohmici. I transienti di corrente mostrano due trappole principali, T1 e T2. L’energia di attivazione, a differenza della sezione di cattura, non è influenzato dalla struttura del dispositivo o dal recesso ai contatti ohmici. I transienti di corrente, le misure gm(f) e lavori precedentemente proposti in letteratura ci permettono di ipotizzare che la trappola T1 sia situata nel buffer layer, a differenza della trappola T1 che è probabilmente sita nello strato AlGaN. Misure al variare del tempo di trapping confermano che entrambe le trappole non sono definite da difetti puntuali.

Les eaux minérales naturelles se distinguent de l’eau potable par leur contenu en sels minéraux et en éléments traces. Leur utilisation à des fins thérapeutiques s’effectue sous contrôle médical dans des établissements thermaux. La gestion des réseaux de distribution ainsi que la qualité microbiologique de l’eau font l’objet de réglementations. Malgré la mise en place de procédures spécifiques, les établissements thermaux sont régulièrement confrontés à des contaminations microbiologiques majoritairement dues à P. aeruginosa. Ce pathogène opportuniste possède d’importantes capacités d’adaptation, de résistance et de persistance dans l’environnement, notamment sous forme de biofilms. L’objectif de ces travaux de thèse est d’apporter des éléments de compréhension sur le comportement de P. aeruginosa dans les réseaux de distribution d’eau minérale naturelle et de valider l’efficacité de produits de traitement. L’influence de la composition minérale de 3 eaux sur les capacités à former du biofilm de 9 souches de P. aeruginosa d’origines diverses a pu être démontrée. Il apparait que les quantités de biofilms produites au bout de 24 h sont moins importantes pour la minéralisation forte. La modulation de la production de facteurs de virulence en fonction de la qualité de l’eau est corrélée à l’action spécifique de certains ions et à la biodisponibilité du fer. En conditions de minéralisation forte il a été montré que les matériaux organiques favorisent la formation de biofilm de P. aeruginosa tandis que les matériaux métalliques ont tendance à la défavoriser. L’efficacité d’une séquence de traitement de postes de soins a pu être validée sur un modèle de biofilm âgé de 24 h et sur tous les matériaux<br>Natural mineral waters are distinguished from drinking water bytheir content in minerals and trace elements. Their use for therapeuticpurposes under medical control is performed in spas. Management ofdistribution networks and the microbiological quality of water are subjectto regulations. Despite the establishment of specific procedures, spas areregularly confronted with microbiological contamination mainly due to P.aeruginosa. This opportunistic pathogen has substantial adaptive capacity,resistance and persistence in the environment, under biofilm.The aim of this thesis work is to bring understanding on the P.aeruginosa behaviour in the natural mineral water distribution networksand validate the effectiveness of treatment products.The influence of the mineral composition of 3 waters on biofilmformation capacity of 9 P. aeruginosa strains of various origins could bedemonstrated. It appears that the amount of biofilm produced after 24 hare less important for the strong mineralization. Modulation of theproduction of virulence factors depending on the water quality iscorrelated to the specific action of certain ions and iron bioavailability. Inhigh mineralization conditions it has been shown that organic materialspromote biofilm formation of P. aeruginosa while metallic materials tendto disadvantage it. The efficiency of a treatment sequence of a patient pointof use has been validated on the 24 h biofilm model and on all materials

Made available in DSpace on 2016-08-10T10:45:24Z (GMT). No. of bitstreams: 1 EDIVANIA ALVES TRIGUEIRO.pdf: 2726333 bytes, checksum: 23ee07079c1e09cd4fc8dd6711876ce6 (MD5) Previous issue date: 2009-06-16<br>The present study approaches the pertinent subject to the Enterprise Hot Rio Resorts in what it refers to the use of potentials hídricos of the State of Goiás and the degradation operated in the areas explored with the construction of the enterprise being analyzed the performance of the collectivity and of the Public Power in the execution of the constitutional beginnings that treat of the protection of the environment as well of use common of the people of the presents and future generations. Among the treated subjects, they are the environmental subject in Brazil, level of importance of the environment, the mobilization degree and participation of the collectivity in the knowledge of the subjects of difficult solution that you/they involve the environment, being discussed, still, the existent tensions in the in the facts and in the experience of rules and your it executes application in the environmental protection. Of the context, they are had that measured of the juridical sphere they are adopted before the conflict of interests characterized by the wide action of the initiative deprived in the materialization of your objectives, inside of the possibility of exploration of resources hídricos, doing with that the Public Administration, so much in the acts entrusted of commission as the ones that are stopped accomplishing it suffers several types of controls of the law and the ones that are not accomplished due to the judiciary authority.<br>O presente estudo aborda a questão pertinente ao Empreendimento Rio Quente Resorts no que se refere ao aproveitamento de potenciais hídricos do Estado de Goiás e a degradação operada nas áreas exploradas com a construção do empreendimento analisando-se a atuação da coletividade e do Poder Público no cumprimento dos princípios constitucionais que tratam da proteção do meio ambiente como bem de uso comum do povo das presentes e futuras gerações. Dentre os assuntos tratados, encontram-se a questão ambiental no Brasil, nível de importância do meio ambiente, o grau de mobilização e participação da coletividade no conhecimento das questões de difícil solução que envolvem o meio ambiente, discutindo-se, ainda, as tensões existentes nos fatos e na experiência de regras e sua efetiva aplicação na proteção ambiental. Do contexto, têm-se que medidas da esfera jurídica são adotadas diante do conflito de interesses caracterizado pela ação ampla da iniciativa privada na concretização de seus objetivos, dentro da possibilidade de exploração de recursos hídricos, fazendo com que a Administração Pública, tanto nos atos encarregados de comissão quanto os que se deixam de cumprir sofra vários tipos de controles da lei e os que não são realizados diante da autoridade judiciária.

Tyrimų tikslas – laboratorinėmis sąlygomis eksperimentiškai nustatyti džiovinimo vainikinio išlydžio elektriniame lauke efektyvumą ir palyginti jį su džiovinimu elektromechaniniu ventiliatoriumi. Darbe aptariami kviečių ir gražgarstės lapų džiovinimo vainikinio išlydžio lauku eksperimentinio tyrimo rezultatai naudojant elektrodų sistemą „lygiagrečių laidų tinklelis virš įžemintos plokštumos“. Darbe apžvelgtos technologijos pagrįstos vainikinio išlydžio lauko naudojimu Tyrimai atlikti Kauno technologijos universitete elektromagnetinių laukų įtaisų mokslinėje laboratorijoje, su įtaisu kurį sudaro aukštos įtampos šaltinis ir elektrodų sistema „lygiagrečių laidų tinklelis virš įžemintos plokštumos“. Atliktas joninio ir elektromechaninio ventiliatoriaus oro srautų palyginimas.<br>The aim of the research is to establish experimentally the effectiveness of drying affected by the corona field in comparison with the effectiveness of drying affected by the external airflow driven by electromechanical ventilator. Review of various techniques applying of corona field is given. Results of wheat drying by using the corona field of electrode system „ a set of parallel wires under the grounded plate“ are presented and discussed. Experimental study of drying is performed in Research laboratory of electromagnetic field devices of Kaunas university of technology. Test drying device consists of the high voltage source and the electrode system „a set of parallel wires under the grounded plate“. Comparison of corona field airflow and electromechanical ventilator airflow is given.

Ces dernières années, les missions spatiales bénéficient d'un regain d'intérêt. Cependant, lorsqu’arrive laphase d’entrée dans l’atmosphère, nous faisons encore face à d’importantes difficultés. Afin de répondre àce problème, une nouvelle technique est proposée : le contrôle par plasma pour augmenter la force detraînée sur le véhicule et ainsi, décroître sa vitesse. Dans cette thèse, un actionneur plasma est testé danstrois écoulements supersoniques (N1(M2-8Pa), N2(M4-8Pa) and N3(M4-71Pa)) et un hypersonique (M20-0.062Pa), ces écoulements étant simulés par la soufflerie MARHy.L’actionneur plasma induit des modifications de l’écoulement autour du modèle étudié, comme unemodification de la géométrie de l’onde de choc et une augmentation de l’angle de choc. Afin de mieuxcomprendre les phénomènes gouvernant ces modifications, la pression Pitot, la température surfacique etvolumique, les données électroniques et des mesures spectroscopiques ont été analysées. Les résultatsmontrèrent que deux types d’effets interviennent : thermiques (surface et volume) et l’ionisation. De plus, il aété démontré que ces effets n’ont pas la même importance suivant les conditions d’écoulements.L’actionneur plasma lui-même a été modifié dans un but d’amélioration. En particulier, deux types degénérateurs ont été étudiés pour alimenter la cathode : DC et pulsé. Finalement, il est montré que pour unepuissance de décharge de 80 W, une augmentation de 13% de la traînée et donc, une diminution de plus de25% des flux de chaleur peuvent être attendus. Par conséquent, les actionneurs plasma semblent être descandidats idéaux pour les missions spatiales et les (r)entrées atmosphérique<br>Space missions are arousing renewed interest in these recent years. However, when coming to the entryinto the atmosphere, major issues are still to be considered. To answer this problem, a new Entry DescentLanding technique is proposed: plasma actuation to increase the drag force over the vehicle body and thus,decrease its speed. In this thesis, a plasma actuator is tested in three supersonic rarefied flows (N1(M2-8Pa), N2(M4-8Pa) and N3(M4-71Pa)) and a hypersonic one (M20-0.062Pa), all generated by the wind tunnelMARHy.The plasma actuator induces flow modifications over the studied model, such as a change in the shock waveshape and an increase in the shock wave angle. In order to better understand the phenomena governingthese modifications, Pitot pressure, surface and gas temperature, electron data and spectroscopicmeasurements were analyzed. The results shown that two types of effects are involved: thermal (bulk andsurface) and ionization. Moreover, it was demonstrated that these effects had not the same importancedepending on the flow conditions.The plasma actuator was also modified in order to improve it. In particular, two types of generators wereused to biase the cathode: DC and pulsed. Finally, it was shown that, for a discharge power of 80 W, a 13%increase in the drag force could be expected and thus, a decrease in the heat load over the model body ofmore than 25%. Therefore, plasma actuators seem to be promising applications for space missions andatmospheric entries

La peau constitue une interface unique entre l’organisme et son environnement extérieur. Son rôle principal est de protéger les organes internes contre les facteurs externes. Le stratum corneum, est la couche supérieure et très hydrophobe de la peau. Elle était considérée peu perméable pour les molécules hydrophiles chargées tels que les ions inorganiques. Plusieurs études ont démontré le contraire et l’étude récente par Paweloszek et al. a indiqué l’importance du transport actif dans le passage cutanée des ions halogénures. L’absorption cutanée des ions classés selon la série de Hofmeister (F-, Br-, I-, SCN, ClO4-) seuls et en mélanges bi- et ternaires a été évaluée dans deux séries d’expériences in vitro. Tous les ions ont pénétré dans la peau viable en 24h. Parmi les halogénures, la presence de F- a diminué l’absorption de Br- et de I- en mélanges, tandis qu’une synergie d’absorption entre Br- et I- a été observée. Dans le second groupe (I-, SCN-, ClO4-), la pénétration cutanée du ClO4- a été inhibé par la présence des autres ions. L’impact de la formulation sur l’absorption cutanée de Ca2+ et Mg2+ présents dans des eaux thermales (TSW) a été évaluée. Différentes formes galéniques telles que des émulsions (TSW/O, O/TSW, TSW/O/W) et des liposomes ont été étudiées. Les liposomes et les émulsions ont favorisé la rétention de ces ions d’intérêt dans les couches cutanées en comparaison à l’eau themale pure. Nos résultats ont démontré que les effets bénéfiques associés aux traitements à base de TSW ne sont pas seulement dus à une action superficielle mais à la pénétration des ions dans la peau. Dans cette thèse nous démontrons la capacité des anions et cations à pénétrer la peau viable in vitro et nous mettons en évidence les effets de mélange et de la formulation sur la pénétration cutanée<br>Human skin forms a unique interface between the body and the external environment. Its main role is to protect the internal organs from external factors. Its highly hydrophobic outermost layer, stratum corneum, has long been believed impermeable for highly hydrophilic compounds, including ions. Several studies proved this concept wrong, and recent research by Paweloszek et al. demonstrated the important contribution of facilitated transport in permeation of halide anions. Skin penetration of anions classified in Hofmeister series (of F-, Br-, I-, SCN, ClO4-) alone and in bi- and ternary mixtures in two experimental series was studied in vitro. All tested ions permeated viable skin within 24h. Among halides, the presence of F- reduced the penetration of Br- and I- in mixtures, and synergy between Br- and I- was observed. Within the second group (I-, SCN-, ClO4-) the inhibition of ClO4- penetration in the presence of other ions was observed. Finally, the impact of formulation of marketed thermal spring water (TSW) into emulsions (TSW/O, O/TSW, TSW/O/W) and liposomes on skin absorption of Ca2+ and Mg2+ was evaluated. Liposomes and emulsions promoted retention of Ca2+ and Mg2+ in skin layers as compared to TSW. Our results prove that the beneficial effects observed during treatment with TSW are associated with penetration of the minerals into and through the skin and are not only a surface action. In this thesis, we demonstrate the possibility of both anions and cations to penetrate viable skin in vitro, and we disclose the effects of mixing and formulating on skin penetration profiles

La technologie de pulvérisation magnétron par impulsions de haute puissance (HiPIMS) a été développée et est considérée comme une méthode efficace pour la préparation des films. La technologie HiPIMS permet une bien plus grande flexibilité pour ajuster la structure et les performances du film, conduisant à des films avec des propriétés uniques qui sont souvent irréalisables dans les autres approches PVD. Cependant, le mécanisme sous-jacent du plasma pour soutenir la croissance du film impliqué est actuellement flou. De plus, la technologie HiPIMS est limitée au laboratoire, de nombreux films aux propriétés souhaitables n'ont pas été explorés dans le cadre de la pulvérisation HiPIMS. Dans ce travail, (i) le l’origine de la structure cohérente du plasma haute densité (les « spokes ») dans la décharge HiPIMS et (ii) comment la structure et les propriétés des films de TaC/a-C:H et HfC/a-C:H sont gérées par HiPIMS ont été étudiés. Dans l'étude du mécanisme de formation des « spokes », basée sur la relation de dispersion du plasma HiPIMS et l'évolution du couplage entre deux ondes azimutales, un modèle d'onde induit par couplage a été proposé. Dans l'étude des films TaC/a-C:H et HfC/a-C:H, les états des liaisons chimiques, la structure, la morphologie, les propriétés mécaniques et tribologiques, la stabilité thermique ainsi que la résistance à l'oxydation des films ont été étudiés. En comparaison avec ces films déposés par pulvérisation magnétron DC, il est démontré que la technologie HiPIMS permet une stratégie potentielle pour préparer des films TaC/a-C:H et HfC/a-C:H plus performants en termes de dureté, de coefficient de frottement et de résistance à l'usure, de résistance à l'oxydation et de stabilité thermique en modulant l'état de liaison chimique et la structure nanocomposite des films à travers un plasma réactif<br>High Power Impulse Magnetron Sputtering technology (HiPIMS) has been developed and considered as an effective method for film preparation. HiPIMS technology allows for much greater flexibility for manipulating film structure and performance, leading to films with unique properties that are often unachievable in the other PVD approaches. However, the underlying plasma mechanism for supporting film growth is currently blurred. Moreover, HiPIMS technology is still stationed in the laboratory, many films with desirable properties have not been explored under HiPIMS framework. In this work, (i) the driven mechanism of high density plasma coherent structure (i.e., spokes) in the HiPIMS discharge and (ii) how the structure and properties of the TaC/a-C:H and HfC/a-C:H films are regulated by HiPIMS were investigated. For the driven mechanism of spokes, based on the dispersion relationship of HiPIMS plasma and the evolution of the coupling between two azimuthal waves, the coupling-induced wave model was proposed. For the TaC/a-C:H and HfC/a-C:H films, the chemical bond states, structure, morphology, mechanical and tribological properties, thermal stability as well as oxidation resistance of the films were investigated. By comparison with DC deposited films, it is demonstrated that HiPIMS technology provides a potential strategy for preparing higher performance TaC/a-C:H and HfC/a-C:H films in terms of hardness, friction coefficient and wear resistance, oxidation resistance and thermal stability by modulating the chemical bonding state and nanocomposite structure of the films through HiPIMS reactive plasma

Resumo Constitui o fulcro deste trabalho o estudo da emergência termal de Sangemil (Beira Alta, Portugal Central). São quatro os vectores principais deste estudo: compreensão do mecanismo de exurgência, da composição química, da termalidade e origem destas águas. O estudo levado a efeito é apresentado ao longo de catorze capítulos, cuja ordenação revelará de certo modo, a metodologia seguida: Um capítulo introdutório, em que se procura fornecer o enquadramento geológico-estrutural das águas termais do país com particular realce para as da região das Beiras. No capítulo 2 faz-se um breve esboço histórico das Termas de Sangemil. Após análise das condições geomorfológicas e climatológicas (capítulos 3 e 4), são expostas as características geológicas e estruturais da área em estudo, que permitiram eleger o modelo geológico-estrutural de controlo na emergência (cap. 5). A abordagem das condições hidrogeológicas (capítulo 6) é feita de maneira qualitativa, por absoluta ausência de dados sobre as características hidráulicas dos aquíferos. No capítulo 7, faz-se o estudo comparativo da água termal versus águas frias locais e apresentam-se os mecanismos hidrogeoquímicos que conduziram às respectivas tipologias químicas. A aplicação da análise factorial como técnica estatística multivariada, possibilitou confirmar algumas conjecturas esboçadas pela apreciação dos dados físico-químicos. Recorremos a todos os geotermómetros químicos de que temos conhecimento, para inferir a temperatura de base da água termal. A utilização dos denominados geotermómetros termodinâmicos, constitui mais uma análise complementar no capítulo sobre geotermometria (capítulo 8). O estudo isotópico (isótopos estáveis e radioactivos) e a termalidade, são os temas desenvolvidos nos capítulos 9 e 10, respectivamente, precedendo o corolário natural de qualquer investigação neste domínio, isto é, a elaboração de um modelo conceptual para o sistema hidrotermal (capítulo 11). Damos ainda conta do actual uso da água termal; focamos as suas potencialidades como recurso energético de baixa entalpia (capítulo 12) e analisamos as vulnerabilidade à poluição no capítulo 13. As principais conclusões deste trabalho expressam-se no capítulo 14.

Tato disertační práce se věnuje studiu částečných výbojů (PD) způsobených poklesem spolehlivosti a životnosti elektronických zařízení a systémů. Diagnostika PD je dnes známá metoda pro vysoké napětí u vysoko-výkonných zařízení. V případě elektronických zařízení PD testování není ale běžně používáná metoda, přestože je zde také potenciál pro vysoké elektrické zatížení vzhledem k velmi krátké vzdálenosti. Tato práce je zaměřena na vyšetřování PD činnosti u elektronických zařízení. Bylo navrženo a provedeno pracoviště pro diagnostiku PD v elektronických zařízeních. Pracovní frekvence se pohybuje od několika stovek Hz až 100 kHz. Maximální amplituda PD testovaného napětí je vyšší než 10 kV. Navzdory jednoduché konstrukci toto zařízení přináší vysokou spolehlivost měření. Více než 300 PD testů bylo provedeno na různých elektronických zařízeních a elektronických součástí,např. na planárních transformátorech a elektronických komponentách používaných při vysoko-napěťových měničích

Ce travail porte sur l'étude de la propagation de décharges couronnes impulsionnelles à pression atmosphérique dans les milieux poreux et/ou alvéolaires. Face à la complexité des phénomènes mis en jeu, liés aux interactions entre la décharge et les surfaces du matériau qui la confine, nous proposons l'étude de décharges confinées par des structures élémentaires. L'étude du confinement radial des décharges, assuré par un large panel de capillaires, a été réalisée. Des diagnostics électriques et optiques de pointe permettent d'étudier la propagation de la décharge au sein des différents capillaires. La corrélation entre ces diagnostics a même permis des mesures de vitesse de propagation au sein de capillaires opaques. Les résultats montrent que la propagation de la décharge dépend grandement de la géométrie des capillaires et des paramètres électriques de génération de la décharge. Dans le cas de sections carrées ou rectangulaires, les arêtes induisent un renforcement local du champ qui attire la décharge. Dans le cas de capillaires cylindriques, le diamètre interne est le paramètre crucial qui détermine aussi bien la structure de la décharge que sa vitesse de propagation. Quelle que soit la nature du capillaire, la propagation présente alors une vitesse optimale à tout autre paramètre constant pour une valeur donnée du diamètre interne. Dans le cas du verre, la vitesse est maximale pour un diamètre interne de 200 µm. L'épaisseur et la permittivité diélectrique du capillaire possèdent également une influence sur la propagation de la décharge radialement confinée. Ainsi, diminuer l'épaisseur ou la permittivité diélectrique engendre une accélération de la décharge. Si l'épaisseur est très faible, la décharge peut même se déconfiner pour se propager à l'extérieur du capillaire. Une étude spectroscopique complémentaire montre que la réduction du diamètre de confinement implique une augmentation de la température du plasma, ce qui pourrait contribuer à l'obtention de ce profil de vitesse en fonction du diamètre de confinement. L'étude du confinement axial des décharges a ensuite été réalisée en insérant des membranes de différentes natures et caractéristiques, perpendiculairement à l'axe pointe plan. Les résultats montrent que la décharge présente une propagation en trois étapes : pointe/membrane, radialement au voisinage de la membrane, puis membrane/plan. Dans cette étude, nous avons mis en évidence l'importance du critère poreux ou non de la membrane. Dans le cas poreux, la propagation de la décharge dans l'ensemble du gap est continue, même pour des pores de l'ordre de la dizaine de µm. Dans le cas non poreux, la propagation est discontinue, et il est nécessaire pour assurer la propagation dans l'ensemble du gap qu'un ré-allumage ait lieu de l'autre côté de la membrane. Après l'instant de l'impact sur la membrane, la décharge marque un arrêt qui correspond à la réorganisation des charges et à la restructuration du champ électrique dans le gap. Elle se propage ensuite radialement au voisinage de la membrane en plusieurs fronts d'ionisation. Si les conditions de claquage sont réunies dans le volume membrane/plan, alors un ré-allumage apparaît à partir de la membrane pour atteindre le plan. L'étude de ces ré-allumages semble montrer l'importance de la position de la membrane au sein de l'espace inter-électrodes et de la dynamique des charges aux surfaces de la membrane. Plus on diminue la distance membrane/plan, plus il est facile d'en observer. Nous montrons également que la diminution de la permittivité diélectrique de la membrane ou l'augmentation de son épaisseur, semble augmenter la probabilité de ces ré-allumages. Dans le cas poreux, nous avons également mis en évidence l'influence de la taille des pores de la membrane sur l'ensemble des étapes de propagation. Lorsque la porosité est inférieure à 100 µm la propagation de la décharge est ralentie du fait de la difficulté de la décharge à traverser directement le matériau.

Les plasmas non-thermiques à haute pression sont très étudiés pour comprendre en détails les mécanismes de développement des décharges qui les créent et les processus cinétiques induits. Ils activent une chimie hors-équilibre spécifique très intéressante pour de nombreuses applications. De fortes concentrations d'espèces très réactives sont ainsi générées avec un coup énergétique relativement faible. A pression atmosphérique, la décharge est généralement filamentaire et instable. Ces dernières années, des études ont mis en évidence de nouveaux types de décharges stables et diffuses, au sens de l'extension spatiale de la décharge qui peut s'étendre sur des échelles centimétriques. Ces décharges sont très intéressantes car elles combinent à la fois un important volume plasmagène, et des champs électriques très élevés. Cependant, la physique de ces décharges est mal connue.Les travaux menés dans cette thèse aborderont tout d'abord des mécanismes physiques de déclenchement de la décharge. Différents régimes de décharge seront présentés par des mesures d’imagerie rapide et par l'étude des signaux électriques. En particulier ils détermineront l'influence de la tension sur les vitesses de propagation et les profils d'intensité lumineuse. Nous mesurerons ensuite la distribution spatio-temporelle du champ électrique et étudierons ces spécificités. Puis nous étudierons comment l'énergie injectée participe à la réactivité chimique de la décharge. Notamment, la température et les densités absolues d’espèces réactives majoritaires (O, O3, N2(B,C)) sont mesurées. Enfin, nous nous intéresserons aux mécanismes de relaxation énergétique en post-décharge. De nombreux diagnostics, souvent complémentaires, permettront de lier la succession des processus physico-chimiques au cours du développement temporel de la décharge depuis son déclenchement jusqu'à sa relaxation complète<br>Non-thermal high-pressure plasmas are extensively studied to understand in detail the development mechanisms of the discharges that create them and the kinetic processes induced. They activate a specific non-equilibrium chemistry that is very interesting for many applications. High concentrations of highly reactive species are thus generated with a relatively low energy consumption. At atmospheric pressure, the discharge is generally filamentary and unstable. In recent years, studies have identified new types of stable and diffuse discharges, in the sense of the spatial extension which can extend over centimetre scales. These discharges are very interesting because they combine both a large plasma volume and very high electric fields. However, the physics of these discharges is not well known.The work carried out in this thesis will addressfirst of all, physical mechanisms of triggering of the discharge. Different discharge regimes will be presented through rapid imaging measurements and the study of electrical signals. In particular, they will determine the influence of voltage on propagation rates and light intensity profiles. We will then measure the spatial and temporal distribution of the electric field and study its specificities. Then we will study how the injected energy contributes to the chemical reactivity of the discharge. In particular, the temperature and absolute densities of the majority of reactive species (O, O3, N2(B,C)) are measured. Finally, we will look at the mechanisms of energetic relaxation in post-discharge. Many diagnostics, often complementary, will make it possible to link the succession of physico-chemical processes during the temporal development of the discharge from its initiation to its complete relaxation

Le secteur industriel du traitement de surface (TS), secteur d’excellence en Bourgogne Franche-Comté, est contraint de recourir à de nouvelles méthodes d’épuration des eaux du fait d’une règlementation européenne de plus en plus stricte. En effet, notamment dans le cadre de la Directive Cadre sur l’Eau, les industriels doivent sans cesse améliorer la qualité de leurs rejets et diminuer les impacts générés par ceux-ci. Ce travail de thèse s’inscrit dans cet objectif. Ainsi, trois grands types d’investigations ont été menés : le premier a permis de définir la composition qualitative et quantitative en substances dangereuses (SD) des rejets de TS et d’étudier leur variabilité temporelle ; le second a validé des modifications d’une station physico-chimique de traitement des eaux franc-comtoise pour diminuer le flux de SD ; le dernier a proposé des solutions innovantes par bioadsorption sur des matériaux de cyclodextrine et par procédé d’oxydation avancée (POA) soit par ozone/UV, soit par l’utilisation de catalyseurs Pd-Cu pour atteindre le même objectif.[...]<br>The industrial sector of surface treatment (ST), sector of excellence in Bourgogne Franche-Comté, is forced to resort to new methods for water treatment due to European regulations increasingly strict. Indeed, particularly in the context of the Water Framework Directive, industries must continually improve the quality of their discharge waters and reduce the impacts generated by them. This work is part of this. Thus, three types of investigations were conducted: the first has defined qualitative and quantitative composition of hazardous substances (HS) in ST discharge waters and study their temporal variability; the second has approved changes in a physicochemical wastewater decontamination station to decrease HS water flow; the last proposed innovative solutions by biosorption on cyclodextrin materials and advanced oxidation process (AOP) by ozone / UV, or by the use of Pd-Cu catalysts to achieve the same objective.[...]

As crescentes exigências sobre o desempenho de sistemas de bombeamento multifásico combinadas aos aspectos relacionados com a maior disponibilidade operacional desses sistemas, bem como as futuras condições de funcionamento atingindo pressões perto de 150 bar, destacam a importância de desenvolver modelos matemáticos precisos para prever o comportamento do desempenho nestes equipamentos. Nesta tese foi aperfeiçoado o modelo termo-hidráulico de uma bomba multifásica de tipo duplo parafuso desenvolvido por Nakashima (2005) e foram incluídos os efeitos da abertura gradual da última câmara, recirculação de líquido entre a sucção e descarga, transferência de calor através do liner e expansão térmica. Uma vez fornecidos os dados geométricos da bomba e as suas condições de operação, é possível calcular os parâmetros de desempenho mais importantes, como: eficiência volumétrica, vazão de sucção e refluxo, potência consumida e distribuição de pressão e temperatura. As equações implementadas foram desenvolvidas a partir dos balanços de massa e energia nas câmaras, tendo em conta a geometria da bomba e a variação das fendas durante sua operação. As rotinas e métodos necessários para a sua solução numérica foram implementadas utilizando programação orientada a objetos (C++). Os resultados fornecidos pelo modelo aperfeiçoado foram comparados com dados experimentais da literatura e uma boa concordância foi encontrada na faixa de até 95 % FVG, nos casos estudados, para bombas com e sem tecnologia de recirculação. Devido à complexidade dos fenômenos físicos envolvidos durante a operação da bomba, o impacto de cada um dos efeitos incorporados nos cálculos do modelo foi avaliado e discutido individualmente. Assim, foi demonstrada a grande influencia da recirculação, da abertura gradual da câmara de descarga e da expansão térmica nos cálculos dos parâmetros de operação mais importantes da bomba. Além disso, a transferência de calor pode ser considerada desprezível, já que seu valor é baixo quando comparado com a potência fornecida pela bomba e, portanto, não influencia os balanços de energia que determinam os estados termodinâmicos das câmaras. No entanto, esse efeito é necessário para calcular a distribuição de temperatura da bomba e a expansão térmica nos parafusos e no liner.<br>The increasing requirements about the performance of multiphase pumping systems combined with those related to a higher operational availability of such systems, as well as future operating conditions with pressure increase at about 150 bar, highlights the importance of developing accurate mathematical models to predict the performance behavior of these equipments. In this thesis it was improved the thermo-hydraulic behavior of a twin screw multiphase pump developed by Nakashima (2005), and were included the effects of the gradual opening of the last chamber, fluid recirculation between suction and discharge of the pump, heat transfer though the liner, thermal expansion and different working fluids (water-air and oil-gas). Giving pump geometry and operational conditions, it is possible to calculate the most important pump parameters performance, such as, volumetric efficiency, suction flow, back-flow, power consumption and pressure and temperature distribution. The model equations were developed based on mass and energy balances in the chambers taking into account the pump geometry and the clearance variation due to operation. Its implementation was made in C++. The results obtained by the new model were compared with experimental data of the bibliography, and a good accuracy was found in it with values till 95% GVF for the studied cases, with and without recirculation technology. Due to the physical phenomenon complexity related with the pump operation, the impact of each effect in the model calculations was evaluated and discussed separately. So, it was demonstrated the importance of the recirculation, the gradual opening of the last chamber and the thermal expansion in the calculation of the most important pump operation parameters. However, the heat transfer can be neglected, because its value is very low when compared with the pump power supply, and therefore, it does not influence the energy balances that determine thermodynamic state in the chambers. However, this effect is necessary to calculate the temperature distribution along the pump and the thermal expansion in the screws and the liner.

This thesis focuses on the process of nanoparticle generation using new source of nonthermal plasma combining corona and pin-hole discharge in liquids. The theoretical part is focused on generation of metallic nanoparticles using various types of plasma discharge, the properties of metallic nanoparticles, their preparation by other methods and methods of characterization of nanoparticles. The experimental part deals with the preparation of copper, silver and gold nanoparticles from solutions of their precursors. The influence of experimental conditions, such as the influence of voltage polarity, effect of precursor concentration, effect of added electrolyte or reducing agent were investigated. All samples were analyzed by UV-VIS spectroscopy. Dynamic light scattering was used to determine the sice of nanoparticles. To confirm the presence of nanoparticles, samples were analyzed using scanning microscope with and energy dispersion spectrometer for elemental analysis.