Dissertations / Theses on the topic 'Window ratio'

Daylight harvesting is an essential strategy that is often used to enhance both the design and performance of an architectural project. Windows, as crucial architectural elements, not only admit natural light into spaces but also provide the occupants with visual connections. However, the excessive usage of windows brings an uncontrolled amount of solar energy to the spaces and negatively affect the building's energy performance. When utilizing passive design strategies such as daylight harvesting, several parameters, including the electrical lighting system, can impact the outcome. The current study investigates the role of lighting systems on daylight harvesting's effectiveness and their impact on window dimension and total energy consumption. In this study, the optimum window-to-wall ratio of an open office in the presence of two different light sources (LED and fluorescent) is explored through a computer simulation method. A combination of tools including AGi32, ElumTools, OpenStudio, EnergyPlus, Radiance, and MATLAB helps to conduct the simulation and deliver optimal results. In the results and conclusion chapter, the study provides guidelines to specify optimal window percentages considering two lighting systems in each cardinal direction. Importantly, the guideline focuses only on energy performance and not on the spatial quality of the design.
Master of Architecture
Harnessing daylight with the use of windows helps to offset parts of the electric lighting needs, and decrease the total building energy consumption. This is accomplished by using glazed materials to admit daylight and lighting control systems, which can respond to the dynamic light level. However, improper implementation of a passive daylighting strategy may cause increased energy consumption. Sunlight is accompanied by solar heat radiation which can increase the HVAC load of a space and compromise the energy savings achieved by daylighting. Therefore, a balance between solar heat and light gain is required to fully take advantage of solar energy without reverse impacts. Concerning the mentioned balance, recent advancements in lighting technology question the effectiveness of natural light in reducing whole-building energy consumption. Due to the high energy efficiency of LED luminaires, lighting power consumption is rather low, even when the lighting system operates at full capacity. Therefore, it is unclear whether the solar energy coming through glazed materials works to the advantage or disadvantage of total building energy consumption. This study hypothesized that the total energy consumption of an open office with LED luminaires would be less in absence of solar energy compared to a scenario which utilizes the solar energy. A simulation-based methodology, using a combination of photometric computation and building energy simulation tools, was utilized to examine the hypothesis and explore the impacts of lighting systems on the optimum window-to-wall ratio. The results provide a helpful guideline which highlights the impact of lighting systems on window dimensions and their mutual effect on whole-building energy consumption. Although the optimum window-to-wall ratios suggested by this study only concern energy consumption, integration of them with occupants' preferences can propose an acceptable window-to-wall ratio that satisfies both design quality and performance of a building.

Wildlife-vehicle collisions (WVCs) negatively impact wildlife populations and create dangerous driving situations for motorists. In Utah, USA, mule deer (Odocoileus hemionus) encounter a variety of hazards as they attempt to cross highways and interstates, some of which are 8 lanes wide. Agencies have sought to mitigate the risks posed to drivers and mule deer by building crossing structures for wildlife. The objectives of this study were to evaluate the effectiveness of crossing structures in Utah to safely pass mule deer under highways and to determine the variables that best explain mule deer passage use. From 2008 - 2011 we used 26 camera traps to measure levels of mule deer use of 9 culverts and 4 bridges in Utah. We tested for relationships between mule deer structure use and a variety of structural and landscape attributes at each site, including 2 time variables: time since the structure was built and time each structure was monitored by our camera traps. We also developed and tested a new equation (window ratio) that measured culvert openness to approaching mule deer. In the single variable regression models, mule deer structure use was positively correlated with short culverts and coarse scale shrub cover, and negatively correlated with fine scale grass cover. In the multivariate model, structure use was positively correlated with days monitored and elevation and short culverts. Although the new window ratio did not emerge as the most important predictor for mule deer crossing use, it was more effective at predicting mule deer culvert use than the often referenced openness factor. Our results indicated that 12 of the 13 crossing structures studied effectively facilitate the movement of mule deer in Utah; however some were used far more than others. We suggest that older crossing structures built with the shortest dimensions possible, with attached wildlife-exclusion fencing, and in shrubby habitat will be most effective at passing a high volume of mule deer under Utah highways.

The main aim of this thesis is to introduce issue of averaging of biological signals. The first part of the thesis deals with the principles of individual averaging methods (constant, floating and exponential window) and describes their basic features. Moreover, the principle of filtered residue, detection of QRS complex, and stretching/shrinking the length of RR-interval to the standardized length are explicated. In the second part of the thesis the outcomes of practically realized (Matlab and GUI) methods of averaging (by final signal-to-noise ratio) are evaluated. Signals from MIT-BIH database are used.

Contribution of daylight to employees in terms of health, productivity, and overall wellness in the office spaces are undeniable. Apart from the psychological and biological benefits of employees, embracing daylight in office spaces increases the energy-efficiency of the building which leads to the sustainable development of a city. However, a considerable number of employees in Sweden lack daylight in their workspaces according to a report by the Swedish Work Environment Authority [Arbetsmiljöverket (Swedish)] (Lowden, 2019). Professionals like Architects, Lighting Designers, and students of architecture and lighting design across Sweden were asked their opinions pertaining to lack of daylight in a considerable number of office spaces in Sweden based on their experience through online questionnaires/ interviews to get to know the overview of this subject. Out of all the possible reasons, window design and economy were the two macro factors according to them that influenced daylight in an office building in Sweden but often, obstruction angle in a building due to urban densification is overlooked when it comes to daylight in an office building. This thesis discusses the influence of obstruction angles with an illustrated office building in Stockholm. Diva for Rhino was the software used for the modelling and daylight simulation.

Energy or DFT detector using a fixed window size is very efficient when signal start time and duration is matched with that of the window'
s. However, in the case of unknown signal duration, the performance of this detector decreases. For this scenario, a detector system composed of multiple windows may be preferred. Window sizes of such a system will also be fixed beforehand but they will be different from each other. Therefore, one of the windows will better match the signal duration, giving better detection results. In this study, multiple window detectors are analyzed. Their false alarm and detection probability relations are investigated. Some exact and approximate values are derived for these probabilities. A rule of thumb for the choice of window lengths is suggested for the case of fixed number of windows. Detectors with overlapping window structure are considered for the signals with unknown delay. Simulation results are added for these types of detectors.

Abstract. It is a growing trend in the modern housing construction especially in northern parts of Europe and America to use modern windows with selective glasses in order to achieve the adequate thermal isolation. The idea is to conserve the energy and discourage the excess use of it following the guidelines of European commission, which aims to achieve zero energy buildings by 2020. Even though the use of such windows do address the energy issue at hand, but on the other hand they cause problems to the radio wave propagation through these windows. The reason for this is the use of metallic coating made of titanium oxide or silver oxide in general on these windows because of their good properties to provide thermal isolation, but are susceptible to deterioration of radio wave propagation through them. Various solutions to this problem have been addressed in this thesis along with their tradeoffs. The previous and current research being carried out to address this issue also have been discussed thoroughly including the research that worked as the motivation to pursue this issue. Amongst others, one solution is the use of passive repeater to achieve the power gain which have been focused on. A prototype repeater antenna developed earlier at CWC and tested through measurements addresses the problem considerably well. Measurements were taken at EMC chamber, University of Oulu, within the frequency range of 700 MHz to 10 GHz, and the results have been compared and analyzed in this thesis. According to our findings, the repeater antenna under the test has shown promising results. In the future work, the proposed repeater can be tested in real life scenarios and its performance can be analyzed within the real life environmental constraints.

Atualmente, os edifícios selados hermeticamente e com as chamadas \"peles de vidro\" estão presentes em diversos países, e possuem, como consequência, um elevado consumo de energia elétrica para conseguir manter o conforto ambiental dos usuários. Contudo, é possível se beneficiar de uma maior eficiência energética nesses espaços através da combinação de soluções ativas e passivas. Esse estudo tem como objetivo principal avaliar a influência de parâmetros de projetos, tais como o formato da sala, tamanho e orientação das aberturas na fachada, no consumo de energia e no conforto visual em saletas comerciais com ventilação híbrida e integração da iluminação natural com a artificial na cidade de São Paulo. As saletas comerciais analisadas possuem uma área média, diferentes formatos e diferentes aberturas em uma só fachada, representando a solução arquitetônica mais comum encontrada nesse tipo de edifício. Através de análise energética realizada por meio do programa EnergyPlus e da análise lumínica com o programa DIVA-for-Rhino, verificou-se que o formato da sala é essencial para a decisão de um percentual de área de abertura na fachada (PAF) que consuma menos energia. Os resultados mostraram que o uso da ventilação híbrida sempre representou uma economia, atingindo uma redução de até 51% do consumo do ar condicionado para resfriamento e até 26% do consumo de energia total, com os PAF´s de 40, 70 e 100%. Seria interessante considerar elementos de proteção solar que não diminuam a eficácia da ventilação e iluminação naturais nesses ambientes, para se aliar o baixo consumo de energia com menores riscos de ofuscamento. Desta forma, o trabalho auxilia a incorporação destas estrategias para uma maior economia de energia no desenvolvimento do projeto arquitetônico desta tipologia de edifício comercial.
Nowadays, sealed airtight office buildings and so-called \"glass curtain wall\" are present in many countries, and have as a result a high consumption of electric energy to be able to maintain the environmental comfort of the users. However, the combination of passive and active strategies could improve the energy efficiency in these spaces. This study aims to evaluate the design parameters influence, such as rooms shape, the openings size and orientation, in the energy consumption and in the visual comfort in cellular offices with hybrid ventilation system and the integration of daylight and artificial lighting in São Paulo. The analyzed cellular offices have an average area, different shapes and different openings in one facade, representing the more common architectural characteristics found in this type of building in that context. Energy analyses in EnergyPlus and daylight studies using DIVA-for-Rhino were conducted. It was found that the rooms shape is essential for the determination of the window-to-wall-ratio (WWR) for reducing energy consumption. The results showed that the hybrid ventilation use always represented an economy, reaching reduction values up to 51% in the consumption of air conditioning for cooling and up to 26% in cellular offices total consumption, with a WWR of 40, 70 and 100%. It would be interesting to consider sun shading elements that do not reduce the effectiveness of natural ventilation and daylighting in these environments to combine low power consumption with a lower risk of glare. In this way, the work helps the incorporation of these strategies for save energy in the development of the architectural design of this type of commercial building.

Vacuum glazing is a vital development in the move to more energy efficient buildings. In vacuum glazing, an evacuated cavity supresses gaseous conduction and convection to provide high thermal resistance. A high vacuum pressure (less than 0.1 Pa) is required and must be maintained by a hermetic seal around the periphery, currently formed with either indium (i.e. low temperature sealing method) or solder glass (i.e. high temperature sealing method). This thesis reports the results of an experimental and theoretical investigation into the development of new low temperature (less than 200°C) and novel high temperature (up to 450°C) glass edge seals. A new low temperature composite edge seal was developed in which double and triple vacuum glazings each of dimensions 300x300mm were fabricated with measured vacuum pressures of 4.6x10-2Pa and 4.8x10-2Pa achieved respectively. A three dimensional finite element model of the fabricated design of composite edge sealed triple vacuum glazing was developed.

In ground based high frequency (HF) radio pumping experiments, absorption of ordinary (O) mode pump waves energises the ionospheric plasma, producing optical emissions and other effects. Pump-induced or natural kilometre-scale field-aligned density depletions are believed to play a role in self-focussing phenomena such as the magnetic zenith (MZ) effect, i.e., the increased plasma response observed in the direction of Earth's magnetic field. Using ray tracing, we study the propagation of ordinary (O) mode HF radio waves in an ionosphere modified by density depletions, with special attention to transmission through the radio window (RW), where O mode waves convert into the extraordinary (X, or Z) mode. The depletions are shown to shift the position of the RW, or to introduce RWs at new locations. In a simplified model neglecting absorption, we estimate the wave electric field strength perpendicular to the magnetic field at altitudes normally inaccessible. This field could excite upper hybrid waves on small scale density perturbations. We also show how transmission and focussing combine to give stronger fields in some directions, notably at angles close to the MZ, with possible implications for the MZ effect. In a separate study, we consider electromagnetic (e-m) beams with helical wavefronts (i.e., twisted beams), which are associated with orbital angular momentum (OAM). By applying geometrical optics to each plane wave component of a twisted nonparaxial e-m Bessel beam, we calculate analytically the shift of the beam's centre of gravity during propagation perpendicularly and obliquely to a weak refractive index gradient in an isotropic medium. In addition to the so-called Hall shifts expected from paraxial theory, the nonparaxial treatment reveals new shifts in both the transverse and lateral directions. In some situations, the new shifts should be significant also for nearly paraxial beams.

This Master thesis was aimed at investigating common daylight evaluation methods related to Swedish building codes versus human perception of daylight in residential spaces. Field (interview) and simulation-based study were conducted in one of the typical 20thcentury residential, closed courtyard buildings in Stockholm.   12 residents of Kv. Väktaren 16 were interviewed and simulation models were prepared for the apartments occupied by the participants.   Resident perception of light was mostly contrary to daylight assessing values and methods of daylight factor – DF in a point (CIE overcast sky) and alternative method of window to floor area ratio – AF that are stated in Swedish standard (Boverkets byggregler BFS 2016:6).    Attractive and interesting view, access to direct sunlight and visual comfort played important role in overall occupant satisfaction level, this suggests that daylight metrics should include perception-based factors, which positively impact our health and well-being.

Massive star winds are understood to be structured. Structures can come in the form of co-rotating interaction regions, which are globally organized flow streams that thread the winds. Structures can also be stochastic in nature, generically referred to as "clumps". The theory for interpreting the radio emissions from randomly distributed microclumps in single star winds is established. Results are presented here for macroclumping, in which the radiative transfer is sensitive to the clump geometry. Two cases are compared: spherical clumps and pancake-like fragments. The geometry of macroclumps can influence the power-law slope of the long wavelength spectral energy distribution.

South Africa produces an average of 154 million broilers (Gallus gallus domesticus) annually, arising to an estimated 886 million kg of broiler litter. The largest population of broilers are reared in the North West province. Various applications for this largely underexploited resource have been published, including forming part of ruminant diets and direct land application. This however has several disadvantages, as it could lead to eutrophication of fresh water sources and faecal contamination of produce. Windrow composting of broiler litter has previously been studied, and found to deliver a stabilized product free of pathogenic and phytotoxic effects, therefore making it an excellent soil conditioner. This study aimed to characterize the microbial community present during the windrow composting of broiler litter. Four different formulations of substrate were tested; these being broiler litter (Windrow 1), Windrow 1 with previously composted material (Windrow 2), Windrow 2 amended with woodchips (Windrow 3) and Windrow 3 with an additional 12.5% (w/w) zeolite (Windrow 4). Broiler litter used in this experiment had a C:N ration of 10.3:1, whilst the blue gum woodchips added as an amendment had a C:N ratio of 172:1. Windrow and environmental temperatures were monitored on a regular basis. Windrow 1 largely mimicked environmental temperature, and could not sustain a true thermophilic phase during the experimental period. Windrow 2 did achieve a short lived thermophilic phase during the first few days of the composting process, however could not sustain its temperature over the whole period. In contrast Windrows 3 and 4 sustained temperature above 40°C for the largest part of the experimental period, regardless of environmental temperature. No significant difference (p < 0.05) could be observed between average moisture levels in the 4 windrows. Internal moisture profiles were however found to differ significantly, especially on the surface of the windrows. Moisture was also lost faster in Windrows 1 and 2 compared to Windrows 3 and 4. Chemical analysis showed differences between the four windrows constructed. A higher amount of nitrogen was lost in Windrows 1 and 2, mostly due to a sub-optimal initial C:N ratio in these windrows. Windrow 2 contained the highest values for plant nutrients P, Mg, Ca, Mn and Cu. Microbial population dynamics were observed using PCR-DGGE of samples collected throughout the composting of various treatments. Various commercial DNA extraction kits where tested in a previous study for their ability to remove PCR inhibitory substances, such as humic acids. The Machery-Nagel Soil DNA isolation kit was used as it gave amplifiable DNA from all samples. Samples were amplified using a nested PCR approach primer sets 27f-1492r \ 341f(GC)-907r and EF3-EF4 \ EF4(GC)-fung5 (where “GC” indicates a GC-rich clamp) for prokaryotic and eukaryotic species respectively. The PCR products were analyzed by agarose gel electrophoresis, and equal amounts of product were subjected to denaturing gradient gel electrophoresis (DGGE). Bands obtained from these polyacrylamide gels where then re-amplified using the same secondary primer sets (without the GC-clamp), and sequenced. A total of 454 prokaryotic bands in 55 distinct rf-positions were observed. Seven distinct rf-positions were observed in eukaryotic DGGE profiles. Prokaryotic profiles were aligned and the microbial diversity was analyzed by means of Ward’s clustering algorithm and the dice coefficient of similarity, as well as Simpson’s reciprocal, Shannon-Weaver and Species richness indices. Canonical correspondence analysis (CCA) was also performed on both the banding patterns as well as the bands present, together with the physico-chemical results obtained. Several bands were successfully identified as being influenced by physico-chemical parameters. Temperature, C:N ratio, ash, and moisture showed a correlation on CCA bi-plots. Sixteen bands were sequence identified. These sequences were compared to two different databases. The 16S rRNA database for Bacteria and Archaea gave identities to genus level, however maximum identity scores were low. Of the 16 sequences, 12 sequences were identified as uncultured bacteria when compared to the nucleotide collection database. In comparing the sequences with sequences collected in the nucleotide collection database, 12 were either first described in composts and soils, or animal manures. Results indicated mostly members of the genus Bacillus and Paenibacillus. The addition of a carbon source greatly affected the microbial metabolism, resulting in a thermophilic phase being achieved in amended windrows. As no thermophilic phase was observed in windrows that were not amended with woodchips, it could be concluded that the use of a carbon source is irremissible when composting broiler litter. A zeolite amendment is also strongly advised, as this further increased temperatures within the windrow.
Thesis (MSc (Environmental Sciences))--North-West University, Potchefstroom Campus, 2013.

It is commonly accepted that the induced noise on DFT phase spectrum has a negligible effect on speech intelligibility for short durations of analysis windows, as the early intelligibility studies pointed out. This fact is confirmed by recent intelligibility studies as well. Based on this phenomenon, classical speech enhancement algorithms do not modify DFT phase spectrum and only make changes in the DFT magnitude spectrum. However, in recent studies it is also indicated that these classical speech enhancement algorithms are not capable of improving the intelligibility scores of noise degraded speech signals. In other words, the contained information in a noise degraded signal cannot be increased by classical enhancement methods. Instead the ease of listening, i.e. quality, can be improved. Hence additional effort can be made to increase the amount of quality improvement using both DFT magnitude and DFT phase. Therefore if the performances of the classical methods are to be improved in terms of speech quality, the effect of DFT phase on speech quality needs to be studied. In this work, the contribution of DFT phase on speech quality is investigated through some simulations using an objective quality assessment criterion. It is concluded from these simulations that, the phase spectrum has a significant effect on speech quality for short durations of analysis windows. Furthermore, phase values of low frequency components are found to have the largest contribution to this quality improvement. Under the motivation of these results, a new enhancement method is proposed which modifies the phase of certain low frequency components as well as the magnitude spectrum. The proposed algorithm is implemented in MATLAB environment. The results indicate that the proposed system improves the performance of the classical methods in terms of speech quality.

La réaction de fusion 12C+ 12C marque un tournant dans l’évolution des étoiles massives. La section efficace présente des résonances jusqu’aux énergies d’intérêt astrophysique, généralement associées à une structure moléculaire dans le 24Mg. Au cours de cette thèse, la section efficace de fusion 12C+ 12C a été mesurée depuis la barrière de Coulomb jusqu’aux énergies d’intérêt astrophysique. La mesure en coïncidence des particules chargées et des γ a été employée. Un dispositif expérimental, STELLA, a été développé et construit au cours de cette thèse. Il comprend une chambre à réaction, des détecteurs annulaires au silicium, un mécanisme de cibles tournantes, un système de pompage pour vide poussé, un système d’acquisition digital, et une structure pour supporter 36 détecteurs LaBr3. STELLA a été installée auprès de l’accélérateur Andromède (Orsay, France) et une série d’expériences fructueuses ont permis d’obtenir des résultats cohérents au cœur de la fenêtre de Gamow pour la phase de combustion du carbone dans les étoiles massives
The 12C+ 12C fusion reaction plays a key role in the late evolution of massive stars. Its cross section exhibits strong resonances down to the astrophysical region of interest, often associated with a molecular configuration of the 24Mg nucleus. In this thesis, the 12C+ 12C fusion cross section has been measured from the Coulomb barrier down to the astrophysical region of interest. The charged particle-gamma coincidence technique has been used. A new experimental setup, STELLA, has been developed and built during this thesis. It is composed of a reaction chamber, a set of annular silicon strip detectors, a rotating target mechanism, an ultra high vacuum system, a digital time-stamped data acquistion system, and a structure that fits 36 LaBr3 detectors. STELLA has been installed at the Andromède facility (Orsay, France). Successfull experiments have been carried out to extract fusion cross sections down to the Gamow window for the carbon burning phase of massive stars

Content of master’s thesis is description field of Sliding window and it’s expansion algorithms, witch are Slow start, Congestion avoidance, Fast Retransmit and Fast Recovery algorithm. Thereinafter is described creation of model in Opnet Modeler’s simulation area. In this simulation area was analyzed reactions of average transfer speed onto variance of data size, lost ratio, latency in short and long time slot and variance of receiver’s buffer size. In last section of this document is method design witch makes it possible of transfer speed control through the use of receiver’s buffer size dynamic setting.

Massive stars have very strong stellar winds which interact with their environment. This work has involved the study of these interactive winds at radio and other wavelengths. Radio observations have been made of the massive runaway star BD+43◦ 3654 and its bow shock which is interacting with the inter-stellar medium. These observations, together with archive data at other wavelengths, have revealed stratified dust and turbulent gas in this interaction zone. Further radio studies have been undertaken of the interaction zones of the colliding winds of massive binary systems. Observations of the colliding wind binary WR 147 at 5GHz have revealed a curved collision zone, suggestive of simple interactive models. Measurements of the flux from the Wolf-Rayet component of this massive binary system has allowed a mass-loss rate to be derived and though the companion O-star is not detected, an upper flux limit has allowed upper limits on the mass-loss rate and limits on the terminal velocity to be inferred. Also revealed is a curious ’bridge’ feature previously observed in WR 147 which occurs between the two binary components. One mechanism is suggested to explain this anomalous feature, the ionising flux of one binary component, the O-star, may be ionising the wind of the other, the WR component. Modelling of the ionisation structure of the stellar winds has been undertaken to verify that this may be occurring. Radio observations of massive stars made at low-frequency have produced detections of WR 147 and the brighter colliding wind binary, WR 146. These detections have allowed modelling of the non-thermal emission in order to deduce where the non-thermal absorption turn-over occurs in these systems. The resultant modelling has illustrated that these colliding wind regions are complex, with multiple absorption regions best describing their nature.

Recombination line profile shapes are derived for ionized spherical stellar winds at radio wavelengths. It is assumed that the wind is optically thick owing to free-free opacity. Emission lines of arbitrary optical depth are obtained assuming that the free-free photosphere forms in the outer, constant expansion portion of the wind. Previous works have derived analytic results for isothermal winds when the line and continuum source functions are equal. Here, semi-analytic results are derived for unequal source functions to reveal that line shapes can be asymmetric about line center. A parameter study is presented and applications discussed.

"This thesis describes the development of an optimized software-defined-radio implementation of a distributed beamforming system and presents experimental results for two-source and three- source wired-channel and acoustic-channel distributed beamforming using the time-slotted round-trip carrier synchronization protocol. The frequency and phase synthesizer used in this system is based on an optimized ``hybrid' phase locked loop (PLL) with averaging window which is shown to have high frequency estimation accuracy and consistency. For the wired-channel experiments, each source node was implemented by a TMS320C6713DSK while for the acoustic experiments, each source node in the system was built using commercial off-the-shelf parts including TMS320C6713DSK, microphone, speaker, audio amplifier, and battery. The source node functionality including phase locked loops and the logic associated with the time-slotted round-trip carrier synchronization protocol was realized through real-time software independently running on each source node's C6713 digital signal processor. Experimental results for two-source and three-source realizations of the wired-channel and acoustic-channel distributed beamforming system are presented. The results show that near-ideal beamforming performance can be consistently achieved at acoustic wavelengths equivalent to common radio frequency wavelengths."

ABSTRACT AN INVESTIGATION OF COMPACTED GRAPHITE IRON PRODUCTION BY MEANS OF THERMAL ANALYSIS TECHNIQUE AND OTHER PROCESS CONTROL WINDOWS El-mabrouk, Omar PhD, Metallurgical and Material Engineering Department Supervisor: Prof. Dr. Ali Kalkanli January 2007, 123 pages Compacted graphite irons have been proved valuable in many applications such as exhaust manifolds, hydraulic valves, and diesel engine blocks, the process of producing compacted graphite irons is not a straight forward process because of its narrow processing windows and its high sensitivity to the section thickness, treatment reaction time, pouring temperatures and charge composition. In this thesis, compacted graphite was produced with minimum variations through all section thickness and the effect of Mg/S ratio, section thickness, and treatment agents on the graphite morphology, electrical resistivity property and fracture strength at high temperatures was investigated. The range of Mg/S ratio and the section thickness was from 2/3 to 7/1 and 5 mm to 40 mm respectively. FeSiMg and FeSiMg cermish metal were used as a treatment agent. Optical metallographic method was implemented to investigate the graphite morphology change. For being a distinguishable characteristic for compacted graphite iron over ductile iron, thermal conductivity changes at high temperatures ranging from room temperature to 500 0C was examined by a suitable electrical setup in the manner of electrical conductivity changes by measuring the electrical resistance. On the other hand, due to the higher values of mechanical properties of compacted graphite iron over those of gray iron, tensile strength was also examined by means of tensile test. The relation between the compacted graphite shape and the alloy properties such as fracture strength and thermal conductivity was investigated. The most important controlling parameters to produce compacted graphite are Mg/S ratio and oxygen activity. The relation between these parameters with both fracture strength and thermal conductivity was established by means of multiple regression analysis technique.

When an aircraft is aerodynamically or structurally damaged in battle, it may not able to complete the mission and the damage may cause its loss. The subject of aircraft battle survivability is one of critical concern to many disciplines, whether military or civil. This thesis considered and focused on Computational Fluid Dynamics [CFD] predictions and experimental investigations into the effects of simulated battle damage on the low-speed aerodynamics of a fmite aspect ratio wing. Results showed that in two-dimensional [2d] and three-dimensional [3D] CFD simulations, Fluent's® models work reasonably well in predicting jets flow structures, pressure distributions, and pressure-coefficient Cp's contours but not for aerodynamic coefficients. The consequences were therefore that CFD prediction was poor on aerodynamic-coefficients increments. The prediction of Cp's achieved good agreement upstream and near the damage hole, but showed poor agreement at downstream of the hole. For the flow structure visualisation, at both weak and strong jet incidences, the solver always predicted pressure-distribution-coefficient lower at upstream and higher at downstream. The results showed relatively good agreement for the case of transitional and strong jet incidences but slightly poor for weak jet incidences. From the experimental results of Finite Wing, the increments for Aspect-ratio, AR6, AR8 and ARIO showed that as damage moves out towards the tip, aerodynamic-coefficients increments i.e. lift-loss and drag-rise decreased, and pitching-moment-coefficient increment indicated a more positive value at all incidence ranges and at all aspect ratios. Increasing the incidence resulted in greater magnitudes of lift-loss and drag-rise for all damage locations and aspect ratios. At the weak jet incidence 4° for AR8 and in all of the three damage locations, the main characteristics of the weak-jet were illustrated clearly. The increments were relatively small. Whilst at 8°, the flow structure was characterised as transitional to stronger-jet. In Finite Wing tests and for all damage locations, there was always a flow structure asymmetry. This was believed to be due to gravity, surface imperfection, and or genuine feature. An 'early strong jet' that indicated in Finite Wing-AR8 at 'transitional' incidence of 8°, also indicated in twodimensional results but at the weak-jet incidence of 4°. For the application of 2d data to AR6, AR8, and ARIO, an assessment of 2d force results led to the analysis that the tests in the AAE's Low Turbulence Tunnel for 2d were under-predicting the damage effects at low incidence, and over-predicting at high incidences. This suggested therefore that Irwin's 2d results could not be used immediately to predict three-dimensional.

This thesis is focussed on the Molonglo Observatory Synthesis Telescope (MOST), reporting on two primary areas of investigation. Firstly, it describes the recent upgrade of the MOST to perform an imaging survey of the southern sky. Secondly, it presents a MOST survey of the Vela supernova remnant and follow-up multiwavelength studies. The MOST Wide Field upgrade is the most significant instrumental upgrade of the telescope since observations began in 1981. It has made possible the nightly observation of fields with area ~5 square degrees, while retaining the operating frequency of 843 MHz and the pre-existing sensitivity to point sources and extended structure. The MOST will now be used to make a sensitive (rms approximately 1 mJy/beam) imaging survey of the sky south of declination -30°. This survey consists of two components: an extragalactic survey, which will begin in the south polar region, and a Galactic survey of latitudes |b| < 10°. These are expected to take about ten years. The upgrade has necessitated the installation of 352 new preamplifiers and phasing circuits which are controlled by 88 distributed microcontrollers, networked using optic fibre. The thesis documents the upgrade and describes the new systems, including associated testing, installation and commissioning. The thesis continues by presenting a new high-resolution radio continuum survey of the Vela supernova remnant (SNR), made with the MOST before the completion of the Wide Field upgrade. This remnant is the closest and one of the brightest SNRs. The contrast between the structures in the central pulsar-powered nebula and the synchrotron radiation shell allows the remnant to be identified morphologically as a member of the composite class. The data are the first of a composite remnant at spatial scales comparable with those available for the Cygnus Loop and the Crab Nebula, and make possible a comparison of radio, optical and soft X-ray emission from the resolved shell filaments. The survey covers an area of 50 square degrees at a resolution of 43" x 60", while imaging structures on scales up to 30'. It has been used for comparison with Wide Field observations to evaluate the performance of the upgraded MOST. The central plerion of the Vela SNR (Vela X) contains a network of complex filamentary structures. The validity of the imaging of these filaments has been confirmed with Very Large Array (VLA) observations at 1.4 GHz. Unlike the situation in the Crab Nebula, the filaments are not well correlated with H-alpha emission. Within a few parsec of the Vela pulsar the emission is much more complex than previously seen: both very sharp edges and more diffuse emission are present. It has been postulated that one of the brightest filaments in Vela X is associated with the X-ray feature (called a `jet') which appears to be emanating from the region of the pulsar. However, an analysis of the MOST and VLA data shows that this radio filament has a flat spectral index similar to another more distant filament within the plerion, indicating that it is probably unrelated to the X-ray feature.

The influence of macroclumps for free–free spectral energy distributions (SEDs) of ionized winds is considered. The goal is to emphasize distinctions between microclumping and macroclumping effects. Microclumping can alter SED slopes and flux levels if the volume filling factor of the clumps varies with radius; however, the modifications are independent of the clump geometry. To what extent does macroclumping alter SED slopes and flux levels? In addressing the question, two specific types of macroclump geometries are explored: shell fragments (pancake-shaped) and spherical clumps. Analytic and semi-analytic results are derived in the limiting case that clumps never obscure one another. Numerical calculations based on a porosity formalism is used when clumps do overlap. Under the assumptions of a constant expansion, isothermal, and fixed ionization wind, the fragment model leads to results that are essentially identical to the microclumping result. Mass-loss rate determinations are not affected by porosity effects for shell fragments. By contrast, spherical clumps can lead to a reduction in long-wavelength fluxes, but the reductions are only significant for extreme volume filling factors.

I present a detailed study of the behaviour of the exotic X-ray binary Cygnus X-3 at radio, (sub)mm, infrared, red-optical and X-ray wavelengths. Further unusual properties of the system are unearthed and previously expounded models are refined by new observations. In order to address the broader picture, a multiwavelength comparison of Cygnus X-3 with other ‘radio-jet’ X-ray binaries is also undertaken. Infrared observations of Cyg X-3 at high time resolution reveal many rapid flare events superimposed upon the 4.8 hr (presumed) orbital motion. Photometry simultaneously in the H & K-bands allows strong constraints to be placed upon T & N_ε for the flaring component. Dereddening of RI- J-H-K-L-L’ photometry places limits on the likely extinction to Cyg X-3 of 4.5 ≤ A_J ≤ 7.5 mag. Further infrared study, simultaneous with radio monitoring and observations with OSSE/GRO and the INT shed greater light on the source, including possible orbital colour changes and a longterm correlation between radio and infrared flux levels. Deep imaging of the field reveals many previously undiscovered infrared sources within a few arcsec of Cyg X-3. Simultaneous millimetre and radio observations of Cyg X-3 reveal anomalously strong mm fluxes. Interpreting this in terms of significant absorption of the cm fluxes during the passage outwards of the radio-emitting plasmons, strengthens the case for a dense stellar wind in the Cyg X-3 system. Further radio and sub(mm) observations of Cyg X-3 during outburst confirm previously observed phenomena such as quenched radio emission prior to outburst, and establish the importance of radiation loss mechanisms in the decay of radio plasmons ejected from the source. A model describing the qualitative behaviour of the source during outburst is presented.

RFID has been characterized as a “disruptive technology” that has the potential to revolutionize numerous key sectors. A key advantage of passive RFID applications is the ability to wirelessly transmit automatic identification and related information using very little power. This paper presents an experimental investigation to inform the optimal configuration for programming passive ultra-high frequency (UHF) RFID media in dynamic applications. Dynamic programming solutions must be designed around the tag’s functionality, the physical programming configuration and environment. In this investigation, we present a methodology to determine an optimal configuration to maximize the systems programming efficiency for dynamic applications.

Supernova (SN) 2005ip was a Type IIn event notable for its sustained strong interaction with circumstellar material (CSM), coronal emission lines and infrared (IR) excess, interpreted as shock interaction with the very dense and clumpy wind of an extreme red supergiant. We present a series of late- time spectra of SN 2005ip and a first radio detection of this SN, plus late-time X-rays, all of which indicate that its CSM interaction is still strong a decade post- explosion. We also present and discuss new spectra of geriatric SNe with continued CSM interaction: SN 1988Z, SN 1993J and SN 1998S. From 3 to 10 yr post- explosion, SN 2005ip's Ha luminosity and other observed characteristics were nearly identical to those of the radio- luminous SN 1988Z, and much more luminous than SNe 1993J and 1998S. At 10 yr after explosion, SN 2005ip showed a drop in Ha luminosity, followed by a quick resurgence over several months. We interpret this Ha variability as ejecta crashing into a dense shell located less than or similar to 0.05 pc from the star, which may be the same shell that caused the IR echo at earlier epochs. The extreme Ha luminosities in SN 2005ip and SN 1988Z are still dominated by the forward shock at 10 yr post- explosion, whereas SN 1993J and SN 1998S are dominated by the reverse shock at a similar age. Continuous strong CSM interaction in SNe 2005ip and 1988Z is indicative of enhanced mass- loss for similar to 10(3) yr before core collapse, longer than Ne, O or Si burning phases. Instead, the episodic mass- loss must extend back through C burning and perhaps even part of He burning.

Globally, there are approximately 900 000 telecommunication radio base station sites (RBS-sites)located in areas without access to the electrical grid. Traditionally, these sites are powered by dieselgenerators, consuming large amounts of fossil diesel fuel. Diesel combustion is connected both toenvironmental impacts and high economical expenses for the mobile operators. As the mobilenetwork expansion is increasingly located in off-grid areas of developing countries, the search forrenewable power alternatives has been intensified. This Master thesis presents results from a life cycle assessment (LCA) of photovoltaic and windturbine hybrid power configurations for off-grid RBS-sites. The LCA covers environmental impactsfrom all life cycle activities of the hybrid system: from raw material extraction, manufacturing, andtransportation, to on-site usage, and disposal. To enable assessment of variable hybrid configurations, four scalable sub-models were constructed:one diesel sub-model including the generator and yearly diesel consumption, one back-up batterysub-model, one PV module sub-model and one wind turbine sub-model. Included in the sub-modelswere required site equipment; e.g. foundations for generators, PV modules and battery banks, powerconverters, fuel tanks and possible housings. The number of generators, liters of fuel consumed peryear, number of battery cells, square meters of PV module and number of wind turbines were set asvariables. Hereby RBS-sites with different capacities and availability of renewable source could bemodeled. A hybrid configuration including 21 square meters photovoltaic modules, one wind turbine, a storageof 36 (12 V) batteries and one generator back-up consuming 1500 liters of diesel fuel per year wasevaluated. The hybrid site represents between 11 and 16 percent of the different environmentalimpact potentials, global warming potential specifically representing 13 percent, caused by acorresponding traditional diesel site consuming 20000 liters of fuel per year. The most importantparameters influencing the environmental performance of the renewable hybrid site following thediesel fuel production and combustion are the production energy mix and energy intensive processesincluding the up-stream silicon and lead processing. The thesis confirmed great environmental benefits of using wind and solar power at RBS-sites. Theadditional gain of applying wind power when feasible to decrease the PV module area or batterycapacity required was also demonstrated. The great importance of manufacturing location andelectricity mix should encourage Ericsson to map supplier manufacturing locations, searchingpossibilities to decrease the environmental impacts from the manufacturing phase of the differentsub-systems.
Idag finns det omkring 5 miljoner radiobasstationer i det i det globala telekomnätet, varav 900000 ärbelägna i områden utan tillgång till elektricitet. Traditionellt drivs dessa stationer av dieselgeneratorersom konsumerar stora mängder diesel. Dieselförbränningen bidrar både till lokala och globalamiljöeffekter samt höga driftkostnader för mobiloperatörerna. Expansionen av mobilnätet sker i alltstörre utsträckning i områden i utvecklingsländer utan elförsörjning, vilket har ökat intresset föralternativa kraftkällor. Inom examensarbetet har ett redskap för jämförande livscykelanalys (LCA) av förnyelsebara krafthybridlösningarför radiobasstationer utvecklats. Hybriderna kombinerar solceller och vindturbinermed dieselförbränning och batterier. Genom att använda LCA inkluderas miljöeffekter från alla steg i hybridsystemets livscykel; frånutvinning av råmaterial och tillverkning av sub-system, transport, användning på RBS-siten till denslutliga avvecklingen. För att kunna utvärdera olika hybridkonfigurationer skapades 4 olika delmodeller: en delmodell fördieselförbränning innefattande generator och dieselkonsumption, en batteri-delmodell, en PVdelmodellsamt en vindturbin-delmodell. Delmodellerna inkluderar även nödvändiga komponentersom betonggrund till generatorer, PV-modulerna och batteribanken. Antal dieselgeneratorer,battericeller, vindturbiner samt PV-moduler och liter dieselkonsumption kan varieras för att simuleraen specifik anläggning. En hybridlösning med 21 m2 solceller, en vindturbin, 36 stycken (12V) battericeller och endieselgenerator som konsumerar 1500 liter diesel per år analyserades. Hybridlösningen ger upphovtill miljöeffekter motsvarande mellan 11 och 16 procent, global uppvärmning motsvarande 13procent, av miljöeffekterna orsakade av en traditionell dieselkonfiguration som konsumerar omkring20000 liter diesel per år. Betydelsefulla parametrar som påverkar miljöeffekterna frånhybridlösningen förutom produktion och förbränning av diesel är vilken elektricitetsmix somanvänds vid tillverkning av de olika komponenterna och energiintensiva processer som kisel- ochblyframställning. Resultaten tydliggör de stora minskningar av miljöeffekterna som en övergång från dieselförbränningtill sol- och vindkraft på RBS-anläggningar kan ge. Den relativa förbättringen av att installeravindturbiner för att minimera mängden sol- och battericeller har även visats. Betydelsen avproduktionsplats och elektricitetsmix för den totala miljöpåverkan bör motivera Ericsson attkartlägga och välja tillverkare som innebär ett litet bidrag till de totala miljöeffekterna.

Depuis la découverte de la faculté d'un instrument radio à détecter les poussières, plusieurs études ont été menées afin de mieux exploiter ce type d'instrument. Le présent travail concerne l'exploitation et l'interprétation des observations de poussières de l'instrument WAVES à bord des deux sondes STEREO à 1 UA, ainsi que la modélisation de leur dynamique dans le milieu interplanétaire. Cette thèse a débuté avec une étude des mesures de poussières de taille micro-métrique. Les résultats ont montré que les données étaient pertinentes dans le sens où malgré les incertitudes sur les données et les simplifications de la modélisation du flux, les mesures de direction fournies par cet instrument sont au moins aussi précises que celles fournies par les instruments conventionnels. Ensuite, nous avons réalisé une étude sur les observations de nanoparticules à 1 UA. Nous avons montré qu'une impulsion caractéristique d'un impact d'une nanoparticule se forme suite à la perturbation temporaire du courant de retour de photo-électrons de l'antenne électrique la plus proche du point d'impact. La comparaison des flux mesurés et déduits des observations réalisées dans deux domaines différents (temporel et fréquentiel) montre une cohérence entre les mesures. Enfin, la modélisation de la dynamique des nanoparticules appuie le fait que des nanoparticules crées près du Soleil sont accélérées par le vent solaire et peuvent atteindre 300 km/s à 1 UA. L'analyse statistique des résultats de cette étude à 1 UA a montré une cohérence avec les mesures obtenues sur STEREO, mais aussi avec l'interprétation de ces mesures et l'estimation de la charge du nuage de plasma
Since the discovery of the ability of a radio instrument to detect dust, several studies have been conducted to determine the physical phenomena underlying measures, the fluxes, and the dust characteristics which can be determined. The present work concerns the exploitation and the interpretation of dust observations made by WAVES instrument onboard the two STEREO probes at 1 AU, as well as modeling of dust dynamics in the interplanetary medium. This thesis began with a study of the sub-micron dust data. The results of this study showed that these data were relevant in the sense that despite the uncertainties on the data and the simplified modeling of the flux, the measurements of the direction provided by this instrument are at least as accurate as those provided by conventional instruments. We, thereafter, began a study of observations of nanoparticles at 1 AU. We showed that a typical pulse generated by a nanoparticle impact is formed by the temporary disruption of the photo-electrons return current of the antenna which is closest to the point of impact. In addition, the comparison of measured and inferred flux observations in two different domains (time and frequency) shows a consistency and agreement between measurements. Finally, the modeling of the dynamics of nanoparticles supports the fact that nanoparticles created near the Sun are accelerated by the solar wind and can reach 300 km/s at 1 AU. Statistical analysis of the results of this study to 1 AU showed a consistency with the measurements obtained with STEREO data, and also with the interpretation of these measurements and the estimation of the electric charge of the plasma cloud

Doutoramento em Física
A temperatura é uma variável chave que afeta a maior parte dos sistemas, quer naturais quer construídos pelo Homem. A medida da temperatura é global, uma vez que regula a cinética e a reatividade daqueles sistemas, ao nível atómico e macroscópico. Os sensores convencionais são ineficientes para a medição remota da temperatura à micro e à nanoescala o que, nos últimos anos, tem inspirado o desenvolvimento de nanotermómetros não-invasivos, sem contato, autorreferenciados e exibindo alta sensibilidade térmica. Neste contexto, a utilização de iões lantanídeos trivalentes (Ln3+), devido às suas propriedades fotoluminescentes que dependem fortemente da temperatura, tem sido uma das aproximações mais promissoras. Esta tese discuta as propriedades de nanopartículas dopadas com iões Ln3+ emitindo na gama espectral do visível e infravermelho-próximo como sensores de temperatura molecular. Na primeira parte da tese, estudaram-se nanopartículas de Gd2O3 dopadas com Nd3+ operando na gama espectral do infravermelho-próximo como nanotermómetros luminescentes baseados num rácio de intensidades. A emissão de nanotubos e nanobastonetes de Gd2O3:Nd3+ foi medida usando um tubo fotomultiplicador R928 comum na primeira janela biológica (800920 nm) tendo-se obtido na faixa fisiológica (288323 K), respetivamente, uma sensibilidade térmica e uma incerteza em temperatura de 1.75±0.04 %K-1 e 0.14±0.05 K. A dependência com a temperatura da emissão de nanoesferas de Gd2O3:Nd3+ na segunda janela biológica (12501550 nm), com excitação a 808 nm na primeira janela biológica, foi, também, estudada mostrando uma sensibilidade térmica máxima de 0.237±0.03 %K-1 a 303 K. Na segunda parte da tese foram desenvolvidas nanopartículas conversoras ascendentes de energia de Gd2O3 e SrF2 dopadas com Yb3+/Er3+ para termometria, tendo como parâmetro termométrico a intensidade integrada das transições 2H11/24I15/2/4S3/24I15/2 do ião Er3+. Desenvolveram-se nanoplataformas combinando nanotermómetros de Gd2O3:Yb3+/Er3+ com nanopartículas de Ouro (nanoaquecedores) para medir a temperatura induzida pelo plasmão das partículas metálicas. A condição ótima para um aquecimento térmico efetivo foi conseguida ajustando a banda de ressonância de superfície localizada do plasmão (LSPR) na gama fisiológica (302330 K). Quando comparadas com as nanopartículas de Gd2O3:Yb3+/Er3+, as nanopartículas de SrF2:Yb3+/Er3+ apresentam uma eficiência de emissão da conversão ascendente de energia e uma dispersibilidade superiores tendo sido estudada a dependência com a temperatura das suas propriedades de emissão, tanto em forma de suspensão como em pó. Além disso, realizaram-se medições do fluxo espectral e do rendimento quântico absoluto de emissão usando um espectrômetro com uma esfera de integração e um medidor de potência. Foi, também, proposto um método inovador para prever a curva de calibração da intensidade de emissão versus temperatura de qualquer termómetro luminescente baseado em dois níveis eletrónicos termicamente acoplados, utilizando como exemplo nanopartículas de SrF2:Yb3+/Er3+.
Temperature is a master variable that affects essentially most of the natural and engineered systems. The measurement of temperature is a virtually ubiquitous requirement as it governs the kinetics and reactivity of these systems from their atomic to macroscopic level. The conventional temperature sensors, proved to be ineffective for remote temperature measurement at the micro and nanoscale. This has been strongly stimulated for the development of non-invasive, noncontact and self-referencing nanothermometers exhibiting high thermal sensitivity. In this context one of the most promising approaches proposes the use of trivalent lanthanide ions (Ln3+) that present photoluminescent properties that are temperature dependent. This thesis reports Ln3+-doped visible emitting upconverting and near-infrared emitting downshifting nanoparticles as molecular temperature sensors. Primarily, Nd3+-doped near-infrared exciting and near-infrared emitting downshifting Gd2O3 nanoparticles as an intensity-based ratiometric nanothermometer were evaluated. The performance of Gd2O3:Nd3+ nanorods were enquired using a common R928 photomultiplier tube in the first transparent biological window (800–920 nm). The highest thermal sensitivity and temperature uncertainty (1.75±0.04 %K−1 and 0.14±0.05 K, respectively) were reported for Gd2O3:Nd3+ nanorods in the physiological range (288–323 K). Similarly, the performance of Gd2O3:Nd3+ nanospheres were briefly investigated for their temperature dependent emission in the second biological window (12501550 nm) upon excitation in the first biological window (at 808 nm). The Gd2O3:Nd3+ nanospheres exhibit a maximum thermal sensitivity of 0.237±0.03 %K-1 at 303 K were obtained. Secondarily, Yb3+/Er3+-doped near-infrared exciting and visible emitting upconverting Gd2O3 and SrF2 nanoparticles were developed for thermometry based on the thermometric parameter, as the integrated intensity of 2H11/2→4I15/2/4S3/2→4I15/2 Er3+ transitions. Gd2O3 nanorods as thermometers combined with Au as heater nanoplatforms were constructed, to measure plasmon-induced temperature increase of Au nanorods. The optimal condition for the effective thermal heating was achieved by tuning the localized surface plasmon resonance band in the physiological range (302–330 K). In order to increase upconversion emission efficiency and the dispersibility, further SrF2 nanoparticles were explored and the thermal sensing properties were exploited both in powder and water suspension forms. Moreover, the measurements of spectral flux and the absolute quantum yield were accomplished followed a method using an integrating sphere-based spectrometer and a power meter. Considered a furtherance step is to demonstrate a straightforward method to predict the temperature calibration curve of any upconverting thermometer based on two thermally-coupled electronic levels independently of the medium, taking SrF2 nanoparticles as an illustrative example.

We present spectral line mapping observations towards four massive star-forming regions Cepheus A, DR21S, S76E and G34.26+0.15 - with the IRAM 30-m telescope at the 2 and 3 mm bands. In total, 396 spectral lines from 51 molecules, one helium recombination line, 10 hydrogen recombination lines and 16 unidentified lines were detected in these four sources. An emission line of nitrosyl cyanide (ONCN, 14(0), 14-13(0), (13)) was detected in G34.26+0.15, as the first detection in massive star-forming regions. We found that c-C3H2 and NH2D show enhancement in shocked regions, as suggested by the evidence of SiO and/or SO emission. The column density and rotational temperature of CH3CN were estimated with the rotational diagram method for all four sources. Isotope abundance ratios of C-12/C-13 were derived using HC3N and its C-13 isotopologue, which were around 40 in all four massive star-forming regions and slightly lower than the local interstellar value (similar to 65). The N-14/N-15 and O-16/O-18 abundance ratios in these sources were also derived using the double isotopic method, which were slightly lower than in the local interstellar medium. Except for Cep A, the S-33/S-34 ratios in the other three targets were derived, which were similar to that in the local interstellar medium. The column density ratios of N(DCN)/N(HCN) and N( DCO+)/N(HCO+) in these sources were more than two orders of magnitude higher than the elemental [D]/[H] ratio, which is 1.5 x 10(-5). Our results show that the later stage sources, G34.26+0.15 in particular, present more molecular species than earlier stage sources. Evidence of shock activity is seen in all stages studied.

Context. High spectral resolution and long exposure times are providing unprecedented levels of data quality of massive stars at X-ray wavelengths. Aims. A key diagnostic of the X-ray emitting plasma are the fir lines for He-like triplets. In particular, owing to radiative pumping effects, the forbidden-to-intercombination line luminosity ratio, R = f∕i, can be used to determine the proximity of the hot plasma to the UV-bright photospheres of massive stars. Moreover, the era of large observing programs additionally allows for investigation of line variability. Methods. This contribution is the second to explore how variability in the line ratio can provide new diagnostic information about distributed X-rays in a massive star wind. We focus on wind integration for total line luminosities, taking account of radiative pumping and stellar occultation. While the case of a variable stellar radiation field was explored in the first paper, the effects of wind variability are emphasized in this work. Results. We formulate an expression for the ratio of line luminosities f∕i that closely resembles the classic expression for the on-the-spot result. While there are many ways to drive variability in the line ratio, we use variable mass loss as an illustrative example for wind integration, particularly since this produces no variability for the on-the-spot case. The f∕i ratio can be significantly modulated owing to evolving wind properties. The extent of the variation depends on how the timescale for the wind flow compares to the timescale over which the line emissivities change. Conclusions. While a variety of factors can ellicit variable line ratios, a time-varying mass-loss rate serves to demonstrate the range of amplitude and phased-dependent behavior in f∕i line ratios. Importantly, we evaluate how variable mass loss might bias measures of f∕i. For observational exposures that are less than the timescale of variable mass loss, biased measures (relative to the time-averaged wind) can result; if exposures are long, the f∕i ratio is reflective of the time-averaged spherical wind.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (Capes)
The poultry industry has sought to optimize animal production. For this reason, the mathematical modeling is an essential tool to achieve greater control and production planning, appropriate to the different feeding conditions, market and economic interests. This study aimed to obtain mathematical models capable of predicting the responses of broiler performance due to changes in levels of energy density, according to the phase and sex, as base to a system of nonlinear feed formulation. Therefore, two experiments were conducted simultaneously, for 240 broiler females and 240 males. The birds were distributed in a completely randomized design with six energy levels (2,800; 2,900; 3,000; 3,100; 3,200 and 3,300 kcal ME/kg, maintaining the relationship between energy and other nutrients) and four replicates of ten birds, allocated to floor pens. Data on body weight, feed intake, energy consumption, feed conversion, carcass weight and abdominal fat were analyzed by response surface methodology. Feed intake and body weight were used to determine rates of gain that maximize economic return, according to the energy density, the market prices of ingredients and kilogram of broilers. It was concluded that the concept of nonlinear formulation seems more appropriate to meet the concept of precision nutrition for broilers, since the requirements of all nutrients are automatically adjusted by the mathematical model related to energy content estimated, according to the nutritional recommendations for different ages and stages of broilers, according to the program PPFR
FAPESP: 2009/09500-0

Resumo:A avicultura de corte tem buscado a otimização da produção animal. Por esta razão, a modelagem matemática representa uma ferramenta imprescindível para se obter um maior controle e planejamento produtivo, adequado às diferentes condições de alimentação, do mercado e interesses econômicos. Assim, este trabalho teve a finalidade de obter modelos matemáticos, capazes de estimar as repostas do desempenho de frangos de corte em razão das mudanças da densidade energética da dieta, segundo a fase de criação e o sexo, como base de um sistema de formulação de rações não linear. Para tanto, foram conduzidos simultaneamente dois experimentos, para 240 frangos de corte fêmeas e 240 machos. As aves foram distribuídas em delineamento inteiramente casualizado com seis níveis de energia metabolizável (2.800; 2.900; 3.000; 3.100; 3.200 e 3.300 kcal/kg, mantendo-se a relação entre os demais nutrientes) e quatro repetições de dez aves, sendo alojadas em piso. Os dados de peso corporal, consumo de ração, consumo de energia, conversão alimentar, peso da carcaça e da gordura cavitária foram analisados segundo a metodologia de superfície de resposta. O consumo de ração e o peso corporal foram utilizados para se determinar as taxas de ganho que maximizam o retorno econômico, de acordo com a densidade energética, os preços de mercado dos ingredientes e do kg do frango. Concluiu-se que o princípio de formulação não linear mostra-se mais apropriado para atender ao conceito da nutrição de precisão para frangos de corte, uma vez que, as exigências de todos os nutrientes são automaticamente ajustadas pelo modelo matemático, relacionados ao teor energético estimado, conforme as recomendações nutricionais distintas para fases e idades de frangos de corte, segundo o programa PPFR
Abstract:The poultry industry has sought to optimize animal production. For this reason, the mathematical modeling is an essential tool to achieve greater control and production planning, appropriate to the different feeding conditions, market and economic interests. This study aimed to obtain mathematical models capable of predicting the responses of broiler performance due to changes in levels of energy density, according to the phase and sex, as base to a system of nonlinear feed formulation. Therefore, two experiments were conducted simultaneously, for 240 broiler females and 240 males. The birds were distributed in a completely randomized design with six energy levels (2,800; 2,900; 3,000; 3,100; 3,200 and 3,300 kcal ME/kg, maintaining the relationship between energy and other nutrients) and four replicates of ten birds, allocated to floor pens. Data on body weight, feed intake, energy consumption, feed conversion, carcass weight and abdominal fat were analyzed by response surface methodology. Feed intake and body weight were used to determine rates of gain that maximize economic return, according to the energy density, the market prices of ingredients and kilogram of broilers. It was concluded that the concept of nonlinear formulation seems more appropriate to meet the concept of precision nutrition for broilers, since the requirements of all nutrients are automatically adjusted by the mathematical model related to energy content estimated, according to the nutritional recommendations for different ages and stages of broilers, according to the program PPFR
Orientador: Manoel Garcia Neto
Banca: Marcos Franke Pinto
Banca: Douglas Emygdio de Faria
Mestre

Abstract 1: A multi-level assessment of disproportionate population sex ratios and high-risk sexual behaviors among STD clinic patients Low male-to-female sex ratios in a population may influence high-risk sexual behaviors, such as multiple sex partners and inconsistent condom use, which facilitate the transmission of STDs. This study used multi-level modeling to assess whether population sex ratios were associated with these two individual-level behaviors. All analyses were stratified by gender. Interview data were collected from patients (N = 9,203, 48% male) attending participating STD clinics. Interviews included information on socio-demographics and sexual behavior, including number of sex partners in the previous 3 months and condom use at last sex. The sex ratio per census tract was obtained from the U.S. Census Bureau. There was no association between sex ratio and multiple sex partners or condom use for either men or women. That is, we found no evidence that a shortage of men in census tracts was associated with increased engagement in high-risk sexual behavior.   Abstract 2: A multi-level assessment of neighborhood vacancy rates and high-risk sexual behaviors among STD clinic patients The “broken windows” theory posits that physical neighborhood deterioration, and its association with reduced social cohesion, can lead to changes in individual behaviors. Thus individuals living in neighborhoods with high levels of deterioration may be more likely to engage in high-risk sexual behaviors. This study used multi-level modeling to evaluate the extent to which high residential vacancy rates increased the likelihood of individuals having multiple sex partners. Interview data, including data on patient demographics and sexual behaviors, were collected from patients (N = 6,347, 52% male) attending participating STD clinics in the Richmond, Virginia area from 2008-2010. Neighborhood vacancy rates were obtained from the U.S. Census Bureau. Fifty-one percent of men and 36% of women reported having 2 or more sex partners in the previous 3 months. Men who lived in census tracts with high vacancy rates were slightly more likely to report multiple sex partners (53.9%) compared to men who lived in low vacancy tracts (49.7%). In multi-level models, there was no association between high vacancy rates and having multiple sex partners among either women (OR = 0.98; 95% CI: 0.79, 1.20) or men (1.18; 95% CI: 0.99, 1.42). That is, we found no evidence that increased neighborhood deterioration, as measured by high residential vacancy rates, was associated with increased risk of having multiple sex partners among STD clinic patients.   Abstract 3: Residential segregation and gonorrhea rates in U.S. metropolitan statistical areas The residential segregation of black populations, often in areas of high economic disadvantage and low social status, may play a crucial role in the observed racial inequities in STD rates. An ecological analysis of 2005-2009 average gonorrhea rates was performed across 277 U.S. metropolitan statistical areas (MSAs). The black isolation index and Gini index of income inequality were used as proxy measures for racial and economic residential segregation respectively, derived from 2005-2009 U.S. Census estimates. We used logistic regression modeling to produce estimates of odds ratios (OR) and 95% confidence intervals (CI) for the association between a high black isolation index and Gini index, both independently and in combination, on gonorrhea rates in MSAs. Effect measure modification was assessed by calculating the relative excess risk due to interaction (RERI) between the two indices. Compared to MSAs with low levels of racial segregation, MSAs with high levels of racial segregation had increased odds of high gonorrhea rates (adjusted OR 5.54; 95% CI: 2.29-13.44). Adjustment for potential confounders did not noticeably impact the relationship between the Gini index and gonorrhea, with higher levels of income inequality predicting higher gonorrhea rates (adjusted OR = 2.47; 95% CI: 1.21-5.03). In combined models, the influence of racial residential segregation on gonorrhea rates was stronger than that of income inequality-based segregation; there was no evidence of additivity or a multiplicative interaction. Residential segregation by race or income equality may be a key component in the perpetuation of high rates of gonorrhea and other STDs among black populations in the U.S.

Geomagnetic pulsations are ultra-low frequency (ULF) oscillations of the geomagnetic field that have been observed in the magnetosphere and on the Earth since the 1800’s. In the 1960’s in situ observations of the solar wind suggested that the source of pulsation activity must lie beyond the magnetosphere. In this work the influence of several solar wind plasma and interplanetary magnetic field (IMF) parameters on Pc3 pulsations are studied. Pc3 pulsations are a class of geomagnetic pulsations with frequency ranging between 22 and 100 mHz. A large dataset of solar wind and pulsation measurements is employed to develop two empirical models capable of predicting the Pc3 index (an indication of Pc3 intensity) at one hour and five minute time resolution, respectively. The models are based on artificial neural networks, due to their ability to model highly non-linear interactions between dependent and independent variables. A robust, iterative process is followed to find and rank the set of solar wind input parameters that optimally predict Pc3 activity. According to the parameter selection process the input parameters to the low resolution model (1 hour data) are, in order of importance, solar wind speed, a pair of time-based parameters, dynamic solar wind pressure, and the IMF orientation with respect to the Sun-Earth line (i.e. the cone angle). Input parameters to the high resolution model (5 minute data) are solar wind speed, cone angle, solar wind density and a pair of time-based parameters. Both models accurately predict Pc3 intensity from unseen solar wind data. It is observed that Pc3 activity ceases when the density in the solar wind is very low, even while other conditions are favourable for the generation and propagation of ULF waves. The influence that solar wind density has on Pc3 activity is studied by analysing six years of solar wind and Pc3 measurements at one minute resolution. It is suggested that the pause in Pc3 activity occurs due to two reasons: Firstly, the ULF waves that are generated in the region upstream of the bow shock does not grow efficiently if the solar wind density is very low; and secondly, waves that are generated cannot be convected into the magnetosphere because of the low Mach number of the solar wind plasma due to the decreased density.

Sweden is working on increasing the share of wind energy, but it comes along with many challenges,one of those challenges is the uncertainty of the wind power; CHP could be an option for betterutilizing of wind power by adapting the power to heat ratio according to wind energy fluctuation.The potential for utilizing installed wind energy in Sweden using CHP plant has been studied. A CHPplant installed in the South of Sweden was considered as studied case. To match the heat andelectricity demand requested by the region with the output from the CHP plant two scenarios weresimulated. Results showed that 5.3 MW of installed wind energy in Sweden could be adjusted andset to a level of 73.6 MW if the CHP plant alone were to cover the heat demand, and 25.4 MW ofinstalled wind power in Sweden could be adjusted and set to a level of 54.2 MW with an additionalheat supply of 8 MW in the studied case.

It is well known that the layout of a large wind turbine cluster aects the energyoutput of the wind farm. The individual placement and distances betweenturbines will in uence the wake spreading and the wind velocity decit. Manyanalytical models and simulations have been made trying to calculate this, butstill there is a lack of experimental data to conrm the models. This thesis isdescribing the preparations and the execution of an experiment that has beenconducted using about 250 small rotating turbine models in a wind tunnel. Theturbine models were developed before the experiment and the characteristicswere investigated. The main focus was laid on special eects occurring in largewind turbine clusters, which were named Global Turbine Array Eects.It was shown that the upstream wind was little aected by a large windfarm downstream, even though there existed a small dierence in wind speedbetween the undisturbed free stream and the wind that arrived to the rstturbines in the wind farm. The dierence in wind speed was shown to beunder 1% of the undisturbed free stream. It was also shown that the densityof the wind farm was related to the reduced wind velocity, with a more densefarm the reduction could get up to 2.5% of the undisturbed free stream at theupstream center turbine. Less velocity decit was observed at the upstreamcorner turbines in the wind farm.When using small rotating turbine models some scaling requirements hadto be considered to make the experiment adaptable to reality. It was concludedthat the thrust coecient of the turbine models was the most important parameterwhen analysing the eects. One problem discussed was the low Reynoldsnumber, an eect always present in wind tunnel studies on small wind turbinemodels.A preliminary investigation of a photo measuring technique was also performed,but the technique was not fully developed. The idea was to take oneor a few photos instantaneously and then calculate the individual rotationalspeed of all the turbine models. It was dicult to apply the technique becauseof uctuations in rotational speed during the experiment, therefore thecalculated values could not represent the mean value over a longer time period.

La spectroscopie de bruit quasi-thermique est une méthode précise de déterminat-ion de la densité et de la température dans les plasmas spatiaux. Lorsqu'une antenne électrique est immergé dans un plasma, elle est capable de mesurer les fluctuations électrostatiques provoquées par le mouvement thermique des particules de plasma. Ces fluctuations sont détectées par la densité de puissance spectrale aux bornes de l'antenne, en observant un spectre à des fréquences comparables à la fréquence plasma électronique aussi bien pour les électrons que pour les protons, car le signal du proton est fortement décalé Doppler vers des fréquences plus élevées en raison de la vitesse de dérive du vent solaire. En plus d'induire le champ électrique fluctuant, une partie des électrons impactent sur la surface de l'antenne, ce qui provoque des perturbations de son potentiel électrique. Le signal provoqué par cette population est directement proportionnelle au flux d'électrons du plasma impactant l'antenne et est dominante si l'antenne a une grande surface. Dans ce travail, nous utilisons la théorie de l'orbite limite pour calculer le flux de particules impactantes pour un plasma non thermique décrit par fonction de distribution de vitesses $kappa$ ou Lorentzienne, communément mesurée dans le vent solaire. L'augmentation de la collecte de particules par des objets cylindriques et sphériques est quantifié et présenté en tant que fonction du potentiel électrostatique de surface et de la fraction des particules supra-thermique. La prise en compte de ces résultats théoriques est absolument nécessaire pour des mesures précises des paramètres du plasma à chaque fois que le bruit d'impact est l'élément dominant dans le spectre de puissance. Ceci est le cas pour STEREO, car les bruit d'impact est dominant pour cette sonde, en raison de la présence d'antennes courtes et épaisses. L'étude approfondie des données sur cette mission est motivée par le fait que ses analyseurs d'électrons sont défectueux depuis le lancement et aucune information sur les électrons thermiques n'est disponible. Les résultats obtenus sont vérifiés en comparant avec les résultats de Wind, montrant une bonne concordance entre les valeurs mesurées par les deux satellites. Les incertitudes des mesures sont déterminées par les incertitudes des instruments utilisés et sont estimés à environ $40%$. Le résultat final de ce travail sera l'établissement d'une base de données des moments d'électrons pour les deux sondes STEREO A et B qui couvriront toute la durée de la mission. Dans une seconde partie de la thèse, nous utilisons l'approche cinétique pour étendre la théorie du bruit quasi-thermique à des plasmas où les collisions des électrons avec les neutres jouent un rôle dominant. Cette technique permet de mesurer la densité et la température des électrons, et aussi la fréquence des collisions en tant que paramètres indépendants. Ceci est obtenu sur une large gamme de fréquences aussi bien en dessous qu'au dessus de la fréquence plasma, pour peu que le rapport entre la fréquence de collision et fréquence de plasma ne soit pas inférieur à 0.1. Les résultats présentés ici peuvent potentiellement être appliqués avec succès dans les plasmas de laboratoire et ionosphères non magnétisés, tandis que pour l'ionosphère de la Terre leur utilisation est limitée aux fréquences basses à cause de la présence d'un champ magnétique fort
The quasi-thermal noise spectroscopy is an accurate method of determination of density and temperature in space plasmas. When an electric antenna is immersed into a plasma, it is able to measure electrostatic fluctuations caused by the thermal motion of plasma particles. These fluctuations are detected as the power spectral density at the antenna terminals, observing a spectrum at frequencies comparable to the electron plasma frequency for both electrons and protons, since the proton signal is strongly Doppler-shifted towards higher frequencies due to the solar wind drift velocity. Beside inducing the fluctuating electric field, some of the electrons are impacting the antenna surface, causing disturbances of the antenna electric potential. The signal caused by this population is directly proportional to the flux of plasma electrons impacting the antenna and is dominant if the antenna has a large surface area. In this work, we use the orbit limited theory to calculate the incoming particle flux for a non-thermal plasma described by $kappa$ velocity distribution function, commonly measured in the solar wind. The increase in the particle collection by cylindrical and spherical objects is quantified and presented as a function of the surface electrostatic potential and the fraction of supra-thermal particles. Including these results into the theory has turned out to be absolutely necessary for accurate measurements of the plasma parameters whenever the shot noise is the dominant component in the power spectrum. This is the case for STEREO because the impact noise is overwhelming on this probe, due to the presence of short and thick antennas. The comprehensive study of data on this mission is motivated by the fact that the electron analyzers are malfunctioning since launch and no information on thermal electrons is available. Results obtained are verified by comparing with the results from Wind, showing a good match between the values measured by the two spacecraft. Uncertainties of the measurements are determined by the uncertainties of the instruments used and are estimated to be around $40%$. The final outcome of this work will be establishing a database of the electron moments in both STEREO A and B that will be covering the entire duration of the mission. In the second part of the thesis, we use the kinetic approach to expand the theory of the quasi-thermal noise to plasmas where electron-neutral collisions play a dominant role. This technique is able to measure the electron density, temperature and the collision frequency as independent parameters using the wide frequency range both below and above the plasma frequency, if the ratio of the collisional to plasma frequency is not smaller than 0.1. The results presented here have can be potentially applied in laboratory plasmas and unmagnetized ionospheres, while at the ionosphere of Earth their use is limited to low frequencies due to the presence of the magnetic field

Abstract This thesis studies the ionospheres of the Earth and Mars by combining the observations of versatile instruments providing information on various aspects of the planetary environments. The work on the terrestrial ionosphere focuses particularly on solar wind–magnetosphere–ionosphere coupling, while the work on the Martian ionosphere is based on the development of a new approach to analyse radio-occultation data to retrieve the atmospheric and ionospheric profiles. In the Earth's ionosphere, two papers study the effects of solar wind high-speed streams on the ionospheric F-region peak electron density and on cosmic noise absorption resulting from the precipitation of energetic (>30 keV) electrons into the D region. For the first paper, a modified version of the superposed epoch analysis method, called phase-locked superposed epoch analysis method, was developed. The main finding is that a depletion near the F-region peak takes place in the afternoon and evening sectors during high-speed stream events. This could be explained by an increase in the electron loss rate as a consequence of ion-neutral frictional heating, which enhances the ion temperature and leads to neutral atmosphere expansion. In addition, dayside and post-midnight F-peak electron density increases are observed, probably related to soft particle precipitation. The second study reveals that cosmic noise absorption occurs during up to 4 days after the arrival of a high-speed stream, as substorm-injected energetic electrons precipitate in the midnight to early-afternoon ionosphere, principally at auroral latitudes. A third study reports for the first time observations of a modulation of cosmic noise absorption at periods near 10 s, associated with pulsating aurora. This suggests that the energetic component of the precipitating ux is modulated consistently with the auroral (1–10 keV) energies. At Mars, radio-occultation experiments have been performed by the Mars Express spacecraft since 2004. In this thesis, a new data analysis approach is developed, based on the numerical simulation of radio wave propagation through modelled Martian atmosphere and ionosphere. This approach enables one to overcome limitations inherent in the classical inversion method which has been in use so far. It also gives access to new parameters such as ion density profiles. The new method is tested by analysing the data from two radio-occultation experiments
Tiivistelmä Tämä väitöskirja tutkii Maapallon ja Marsin ionosfäärejä yhdistämällä useiden eri instrumenttien havaintoja, joilla saadaan tietoa planeettojen ympäristöistä. Maapallon ionosfääriä koskeva työ tutkii aurinkotuuli–magnetosfääri–ionosfäärikytkentää, kun taas Marsin ionosfääriä koskevan työn tavoite on uuden radio-okkultaatiomittauksen data-analyysimenetelmän kehittäminen, joka tuottaa ilmakehän ja ionosfäärin profiileja. Maan ionosfäärin tapauksessa yhdessä julkaisussa tutkitaan nopeiden aurinkotuulivirtausten vaikutuksia F-kerroksen elektronitiheyteen ja toisessa julkaisussa tutkitaan energeettisten (>30 keV) elektronien sateesta johtuvaa kosmisen radiokohinan absorptiota D-kerroksessa. Ensimmäisessä julkaisussa on kehitetty uusi versio data-analyysimenetelmästä, jota kutsutaan vaihelukituksi epookkien superpositiomenetelmäksi. Julkaisun päätulos on, että nopeiden aurinkotuulivirtausten aikana F-kerroksen maksimielektronitiheys pienenee iltapäivän ja illan sektoreilla. Tämä voidaan selittää johtuvan siitä, että ioni-neutraalitörmäysten synnyttämä kitkalämpö kasvattaa ionilämpötilaa ja aiheuttaa lisäksi ilmakehän laajenemisen. Molemmat prosessit kasvattavat elektronien häviönopeutta. F-kerroksen elektronitiheysmaksimi puolestaan kasvaa sektorilla, joka ulottuu keskiyöstä aamun kautta keskipäivään, ja tämä johtuu matalaenergeettisestä elektronisateesta. Toisessa julkaisussa havaitaan, että lisääntynyt kosmisen radiokohinan absorptio kestää jopa neljä päivää nopean aurinkotuulivirtauksen saavuttua Maan kohdalle. Tämä johtuu siitä, että alimyrskyitse injektoidut energeettiset elektronit satavat keskiyön ja aamun ionosfääriin, pääasiassa revontuliovaalin alueella. Kolmas julkaisu raportoi ensimmäistä kertaa havainnon sykkiviin revontuliin liittyvästä kosmisen radiokohinan absorptiosta n. 10 s jaksollisuudella. Tämä osoittaa, että elektronivuon energeettinen komponentti on moduloitu samalla jaksollisuudella kuin revontulielektronien energiat (1–10 keV). Marsissa on tehty radio-okkultaatiomittauksia vuodesta 2004 saakka Mars Express -luotaimen avulla. Vaitoskirjassa on kehitetty uusi datan analyysimenetelmä, joka perustuu numeeriseen simulointiin radioaaltojen etenemisestä Marsin ilmakehässä ja ionosfäärissä. Tämän lähestymistavan avulla vältetään tähän asti käytetyn klassisen inversiomenetelmän rajoitukset. Lisäksi menetelmä tuottaa uusia parametrejä kuten ionitiheysprofiileja. Uutta menetelmää testattiin tulkiten kahden radio-okkultaatiomittauksen aineistoa
Résumé Le travail présenté dans ce manuscrit de thèse s'articule autour de l'étude des ionosphères terrestre et martienne. Une approche multi-instrumentale est adoptée afin de combiner des observations permettant de mettre en perspective des manifestations de phénomènes physiques de natures différentes mais intervenant dans un même contexte global. Le travail doctoral comporte également un volet modélisation. Le manuscrit de thèse consiste en une partie introductrice à laquelle sont adossées cinq publications dans des revues scientifiques à comité de lecture. La partie introductrice de ce manuscrit de thèse a pour objectif de présenter le contexte scientifique sur lequel est basé le travail doctoral. Un premier chapitre passe en revue les principaux aspects théoriques dans lesquels s'inscrivent les études dont les résultats sont publiés dans les cinq articles. Les atmosphères et ionosphères de la Terre et de Mars y sont succinctement décrites, de même que les interactions entre ces planètes et le vent solaire, comprenant notamment la formation de magnétosphères. Les deux chapitres suivants présentent les instruments dont sont issues les données utilisées dans ce travail doctoral ainsi que les méthodes d'analyse des données. Le quatrième chapitre résume les principaux résultats obtenus autour des trois grandes thématiques abordées au cours de cette thèse. Enfin, des pistes quant à la continuation potentielle du travail présenté dans ce manuscrit de thèse sont évoquées en conclusion. Le premier article porte sur une étude statistique des effets des courants de vent solaire rapide sur la région F de l'ionosphère aurorale. Il s'appuie sur des données mesurées par l'ionosonde de Sodankylä entre 2006 et 2008. Au cours de cette période, 95 événements associés à des courants de vent solaire rapide ont été sélectionnés, et la réponse de l'ionosphère au-dessus de Sodankylä a été étudiée à partir des fréquences critiques des régions E et F de l'ionosphère, qui donnent la valeur du pic de concentration électronique dans ces deux régions. Pour cela, une version modifiée de la méthode des époques superposées a été développée, appelée “méthode des époques superposées avec verrouillage de phase”. Une augmentation du pic de concentration des régions E et F est observée du côté nuit et le matin, en lien avec une activité aurorale accrue, tandis qu'une déplétion de la région F est révélée aux temps magnétiques locaux situés entre 12 h et 23 h. Une estimation des effets d'une possible modification de l'équilibre photo-chimique résultant d'un accroissement du chauffage issu de la friction entre les ions et les éléments neutres est proposée. Le deuxième article s'intéresse aux précipitations énergétiques dans l'ionosphère aurorale durant ces mêmes 95 événements, en étudiant l'absorption du bruit cosmique qui en résulte. Il apparaît que les événements au cours desquels le vent solaire demeure rapide pendant plusieurs jours produisent davantage de précipitations énergétiques, qui peuvent atteindre les latitudes subaurorales. Par ailleurs, trois types de précipitations énergétiques sont étudiés séparément, selon qu'elles sont associées avec des signatures de sous-orage magnétique, avec des pulsations géomagnétiques, ou ni l'un ni l'autre. Les deux premiers types de précipitations semblent liés. En effet, l'analyse des données suggère que les électrons énergétiques sont injectés dans la magnétosphère interne durant les sous-orages. Tandis qu'une partie d'entre eux précipitent immédiatement du côté nuit, d'autres dérivent vers le côté matin, où ils subissent des interactions avec des ondes électromagnétiques de type siffleur (whistler en anglais), qui peuvent être modulées par des pulsations géomagnétiques, menant à leur précipitation. Le troisième article présente pour la première fois l'observation de signatures d'aurore pulsante dans des données d'absorption du bruit cosmique. Ces signatures sont consistantes avec les pulsations observables dans l'émission aurorale, et semblent indiquer une modulation cohérente des composantes aurorale (1–10 keV) et énergétique (> 30 keV) du spectre des précipitations électroniques au cours d'une aurore pulsante. Le quatrième article introduit une nouvelle méthode proposée pour analyser les données de radio-occultation mesurées par la sonde Mars Express. Cette approche vise à contourner des difficultés posées par les hypothèses fortes nécessaires à la mise en œuvre de la méthode classique d'inversion, notamment celle d'un environnement martien à symétrie sphérique — qui n'est pas acceptable lors de sondages proches du terminateur jour-nuit. La nouvelle méthode est basée sur la modélisation de l'atmosphère et de l'ionosphère de Mars, et sur la simulation de la propagation des ondes radio entre la station sol sur Terre et Mars Express lors d'une expérience de radio-occultation. Les paramètres libres contrôlant les profils atmosphériques et ionosphériques sont ajustés afin que la simulation reproduise le plus fidèlement possible les mesures. Le cinquième article est une réponse à un commentaire sur l'article précédent. Il vise d'une part à répondre aux critiques émises sur la méthode développée, montrant que celles-ci n'en remettent en cause ni la validité ni la pertinence, et d'autre part à y apporter quelques améliorations

O presente trabalho tem como objetivo estudar escoamentos de tornados e sua ação sobre corpos imersos empregando ferramentas numéricas da Engenharia do Vento Computacional (EVC). Os tornados constituem-se atualmente em uma das causas de desastres naturais no Brasil, especialmente nas regiões sul e sudeste do país, como também em alguns países vizinhos. Os efeitos gerados são geralmente localizados e de curta duração, podendo ser devastadores dependendo da escala do tornado. Tais características dificultam a realização de estudos detalhados a partir de eventos reais, o que levou ao desenvolvimento de modelos experimentais e numéricos. A abordagem numérica é utilizada neste trabalho para a simulação de tornados, a qual se baseia nas equações de Navier-Stokes e na equação de conservação de massa, considerando a hipótese de pseudo-compressibilidade e condições isotérmicas. Para escoamentos com turbulência utiliza-se a Simulação Direta de Grandes Escalas com o modelo clássico de Smagorinsky para as escalas inferiores à resolução da malha (Large Eddy Simulation ou LES em inglês). A discretização das equações fundamentais do escoamento se realiza com um esquema explícito de dois passos de Taylor-Galerkin, onde o Método dos Elementos Finitos é empregado na discretização espacial utilizando-se o elemento hexaédrico trilinear isoparamétrico com um ponto de integração e controle de modos espúrios Na presença de corpos imersos que se movem para simular os deslocamentos dos tornados, o escoamento é descrito cinematicamente através de uma formulação Arbitrária Lagrangeana-Euleriana (ALE) que inclui um esquema de movimento de malha. Tornados são reproduzidos através da simulação numérica de dispositivos experimentais e do Modelo de Vórtice Combinado de Rankine (RCVM). Exemplos clássicos da Dinâmica dos Fluidos Computacional são apresentados inicialmente para a verificação das ferramentas numéricas implementadas. Finalmente, problemas envolvendo tornados móveis e estacionários são analisados, incluindo sua ação sobre corpos imersos. Nos modelos baseados em experimentos, a variação da relação de redemoinho determinou os diferentes padrões de escoamento observados no laboratório. Nos exemplos de modelo de vórtice, quando o tornado impactou o corpo imerso gerou picos de forças em todas as direções e, após a passar pelo mesmo, produziu uma alteração significativa na estrutura do vórtice.
Analyses of tornado flows and its action on immersed bodies using numerical tools of Computational Wind Engineering (CWE) are the main aims of the present work. Tornadoes are currently one of the causes of natural disasters in Brazil, occurring more frequently in the southern and southeastern regions of the country, as well as in some neighboring countries. Effects are usually localized, presenting a short time interval, which can be devastating depending on the scale of the tornado. These characteristics difficult to carry out detailed studies based on real events, leading to the development of experimental and numerical models. The numerical approach is used in this work for the simulation of tornadoes, which is based on the Navier-Stokes equations and the mass conservation equation, considering the hypothesis of pseudo-compressibility and isothermal conditions. For turbulent flows, Large Eddy Simulation (LES) is used with the classical Smagorinsky model for sub-grid scales Discretization is performed the explicit two-step Taylor-Galerkin scheme, where the Finite Element Method is used in spatial discretization using isoparametric trilinear hexahedral elements with one-point quadrature and hourglass control. In the presence of immersed bodies that are moving in order to simulate translating tornadoes, the flow is kinematically described through a Lagrangian-Eulerian Arbitrary (ALE) formulation, which includes a mesh motion scheme. Tornadoes are reproduced using numerical simulation of experimental devices and the Rankine Combined Vortex Model (RCVM). Classical examples of Computational Fluid Dynamics are presented initially for the verification of the numerical tools implemented here. Finally, problems involving moving and stationary tornadoes are analyzed, including their actions on immersed bodies. For models based on experiments, the variation of the swirl ratio determined the different flow patterns observed in the laboratory. In the vortex model examples, when the tornado impacted on the immersed body, peaks of forces were generated in all directions and, after passing over it, a significant change in the structure of the vortex was produced.