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1
Piao, Dongzhen. "Speeding Up Gibbs Sampling in Probabilistic Optical Flow." Research Showcase @ CMU, 2014. http://repository.cmu.edu/dissertations/481.
Full textAbstract:
In today’s machine learning research, probabilistic graphical models are used extensively to model complicated systems with uncertainty, to help understanding of the problems, and to help inference and predict unknown events. For inference tasks, exact inference methods such as junction tree algorithms exist, but they suffer from exponential growth of cluster size and thus is not able to handle large and highly connected graphs. Approximate inference methods do not try to find exact probabilities, but rather give results that improve as algorithm runs. Gibbs sampling, as one of the approximate inference methods, has gained lots of traction and is used extensively in inference tasks, due to its ease of understanding and implementation. However, as problem size grows, even the faster algorithm needs a speed boost to meet application requirement. The number of variables in an application graphical model can range from tens of thousands to billions, depending on problem domain. The original sequential Gibbs sampling may not return satisfactory result in limited time. Thus, in this thesis, we investigate in ways to speed up Gibbs sampling. We will study ways to do better initialization, blocking variables to be sampled together, as well as using simulated annealing. These are the methods that modifies the algorithm itself. We will also investigate in ways to parallelize the algorithm. An algorithm is parallelizable if some steps do not depend on other steps, and we will find out such dependency in Gibbs sampling. We will discuss how the choice of different hardware and software architecture will affect the parallelization result. We will use optical flow problem as an example to demonstrate the various speed up methods we investigated. An optical flow method tries to find out the movements of small image patches between two images in a temporal sequence. We demonstrate how we can model it using probabilistic graphical model, and solve it using Gibbs sampling. The result of using sequential Gibbs sampling is demonstrated, with comparisons from using various speed up methods and other optical flow methods.
2
Castledine, Andre J. "Investigation of the fluid flow around blunt body samplers." Thesis, University of Leeds, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.305756.
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Wei, Jian. "Microcolumn field sampling and flow injection techniques for mercury speciation." Thesis, Sheffield Hallam University, 1993. http://shura.shu.ac.uk/20513/.
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Mercury is one of the most toxic heavy metals, and many serious incidents have resulted from mercury poisoning. The methylation of mercury and its amplification by marine life have aggravated this pollution problem. Studies over the last three decades have shown that the toxicity of mercury is related to chemical form. A basic aim of the research has been to devise new methodology for the measurement and speciation of mercury. Key points of the investigation reported were the literature review of methodologies and techniques for mercury speciation and the development of a novel manifold which incorporates microcolumns of sulphydryl cotton which have a relatively high affinity and selectivity for inorganic and / or organomercury, and to utilise a continuous flow procedure for mercury speciation based on flow injection-atomic fluorescence spectrometry. This new and novel system has been used for the determination and speciation of mercury in a variety of water samples. The other column packing materials, eg. xanthate cotton, activated alumina and 8-hydroxy-quiniline were also investigated. A further aspect of element speciation concerns the development of a field sampling technique using sulphydryl cotton columns. Sample collection and preconcentration using microcolumns at the site of sampling was successfully performed. Preliminary experiments indicated that the field sampling technique in combination with FIA-AFS was a robust and potentially useful speciation tool. Field surveys on mercury distribution and speciation in the Manchester Ship Canal and the River Rother have been intensively carried out in collaboration with the National Rivers Authority (North West Region). The analytical data on different mercury species in waters of the Manchester Ship Canal are reported for the first time. A high correlation between organomercury and organolead in the Manchester Ship Canal is found and the related data have been assessed in order to clarify the possible origins for organomercury. Related work concerning participation in interlaboratory studies is reported in the Appendices.
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Xillo, Olivier III. "A Sampling Probe for Fluctuating Concentration Measurements in Supersonic Flow." Thesis, Virginia Tech, 1998. http://hdl.handle.net/10919/36670.
Full textAbstract:
The study of mixing processes in supersonic flow has a great
interest for a number of applications including scramjet
developments. However, the usual tools employed are very
limited. Sampling probes generally have a poor frequency
response, and that makes measurements of fluctuating
concentration problematic. The goal of this study is to
design, build and test a probe capable of measuring
concentration fluctuations of at least 1 kHz. This study
shows the design of such a probe and how a high frequency
response was achieved. A prototype was built and tested.
The tests consist of a calibration phase and experiments
inside a hypersonic wind tunnel. These last tests served
two purposes. The first one was to verify that the
measurements made with the probe gave the correct value of
the concentration. The second purpose was to assess the
frequency response of the probe by putting it through a
concentration step change. Tests were conducted with
various known mixtures of Helium and air from 0% to 100%
flowing at Mach 2.0 with Tt=300 degree K and Pt=4.4 atm.
The probe proved capable of measuring concentration
fluctuations up to approximately 2.5 kHz while also giving
the adequate accuracy for values of mean concentration.<br>Master of Science
5
Leitch, Katherine McArthur. "Estimating Tributary Phosphorus Loads Using Flow-Weighted Composite Storm Sampling." Thesis, Virginia Tech, 1998. http://hdl.handle.net/10919/10078.
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Quantification of total phosphorus (TP) loads entering a lake or reservoir is important because phosphorus is most often the limiting nutrient in terms of algae growth, thus phosphorus can control the extent of eutrophication. Four methods for assessing the annual tributary phosphorus loads to two different Virginia reservoirs were analyzed, three methods that use tributary monitoring program data and one that uses land-use and rainfall data. In this project, one tributary has been extensively monitored for many years and served as a control on which the other methods were tested. The key difference between this research and previous studies is the inclusion of flow-weighted composite storm sampling instead of simple grab sample analyses of storm flow. Three of the methods employed flow stratification, and the impact of the base flow separation point was examined. It was found that the Regression Method developed in this research was the least sensitive to the base flow separation point, which is a valuable attribute because a wrong choice will not significantly affect the estimate. The Monte Carlo Method was found to underestimate the TP loads. The amount of rainfall impacted the accuracy of the methods, with more error occurring in a year with lower precipitation.<br>Master of Science
6
Cahn, Lorie Selma. "Development of guidelines for design of sampling programs to predict groundwater discharge." Thesis, University of British Columbia, 1987. http://hdl.handle.net/2429/26178.
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The objective of this study is to develop guidelines for the design of sampling programs to predict groundwater discharge. A method for choosing a preferred sampling strategy from a set of alternatives is presented. A framework is outlined, in the form of an objective function, that incorporates both the cost of collecting data and the worth of data. A monetary value is assigned to the worth of hydraulic conductivity data by examining the economic losses associated with the uncertainty in predictions of groundwater discharge. The method is applied to the problem of designing a sampling program that measures hydraulic conductivity for predicting discharge from a rapid infiltration pond.
Hydraulic conductivity data are generated for hypothetical hill slopes using a stochastic finite element model. A set of sampling strategies are selected. For each sampling strategy, the value and location of measurements and the uncertainty in the spatial variation of hydraulic conductivity are incorporated using conditional simulations. Estimates of pond discharge are calculated from the stream function solution and compared to the actual value of pond discharge for the hypothetical site. The root mean square error is used to quantify the uncertainty in discharge predictions. A set of alternative sampling strategies are compared using the objective function.
Prediction uncertainty, measured by the root mean square error, is sensitive to both the structure of the heterogeneities and the location of measurements. Sampling schemes that lead to good estimates of the ensemble mean and standard deviation will not necessarily lead to good predictions of discharge. The goal of sampling schemes should be to collect data in key locations of the flow domain and to identify the spatial variation in hydraulic conductivity in a cost effective manner. For predicting discharge from a rapid infiltration pond, locating one or two initial boreholes below the pond is the preferred strategy for a majority of the cases tested. When the measurements are spaced evenly throughout the flow domain, important shallow layers may be missed that have a large influence on pond discharge. Increasing the number of boreholes does not necessarily lead to more certain predictions of pond discharge or to lower values of the objective function. Considerable uncertainty in discharge predictions can exist even with a relatively large number of measurements. While an optimal strategy exists, there is potential for significant variation in prediction uncertainty at individual sites.<br>Science, Faculty of<br>Earth, Ocean and Atmospheric Sciences, Department of<br>Graduate
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Fernandez, Maria Luz Mena. "Field sampling and flow injection strategies for trace analysis and element speciation." Thesis, Sheffield Hallam University, 1997. http://shura.shu.ac.uk/19646/.
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Over the last two decades research has shown that the different forms of trace elements in the environment can cause a variety of health concerns as a result of differences in toxicity. The need to establish efficient, effective and reliable speciation methods has become paramount. A basic aim of this work has been to advance speciation measurement capability for key trace elements (mercury, lead and chromium) by devising an integrated analytical approach that links the sample collection, sample preservation and laboratory measurements in an unified manner. An introductory chapter first reviews the occurrence of organometallic compounds in the environment and focuses on the identification of the "environmental compartments" where transformations of such species can take place. Speciation studies also assist in understanding the biogeochemical cycling of trace elements. Moreover, a review of the various methodologies used for trace element speciation measurements including hyphenated techniques and/or a variety of chemical/physical pretreatments in combination with flow injection (FI) is discussed. Chapter 2 describes mercury speciation experiments utilising gas chromatography-microwave induced plasma-atomic emission spectrometry (GC-MIP-AES) and FI. The approach was based on the preconcentration of mercury on sulphydryl cotton and after elution from the microcolumn, separation and quantitation of methyl-, ethyl- and inorganic mercury species. Method development experiments were performed using a derivatisation technique which gave low contamination and allowed rapid analysis of samples. The microcolumn technique was transferred to the field and speciation of mercury in surface waters of the Manchester Ship Canal was undertaken and high methylmercury concentrations (0.052-0.182 ug 1 -1, as Hg) were detected. In so doing the new approach offered the preservation of the natural speciation state of the water sample directly at the sampling site and during the interval between collection and analysis. In chapter 3 lead studies are centred on the development of a rapid speciation scheme for neutral and cationic (organic and inorganic) lead species based on activated alumina microcolumn separation in combination with ICP-MS and FI. The approach permitted rapid assessment of the nature of lead contamination in environmental waters. Speciation of lead in surface waters of the Manchester Ship Canal was also undertaken using the field sampling approach in an attempt to confirm a transmethyllation reaction between organolead and inorganic mercury. A further application for microcolumns, in the context of speciation measurement, is their use as external calibrants and certified reference materials (CRMs) and this is discussed in the penultimate chapter. Key elements were mercury and chromium. After immobilisation of mercury species on SCF microcolumns it was found that recoveries for methyl- and inorganic mercury were quantitative over 4 months in contrast to ethylmercury which was 2 months. Similar studies for chromium species indicated ineffective elution and more vigorous conditions (microwave assisted digestion) for the elution step were used. A final chapter reviews progress and recommendations are given concerning future research and application for microcolumn field sampling in combination with instrumental analytical techniques.
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Murray, Jacolin Ann. "High Flow Air Sampling for Field Detection Using Gas Chromatography-Mass Spectrometry." BYU ScholarsArchive, 2010. https://scholarsarchive.byu.edu/etd/2414.
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The ability to rapidly detect and identify hazardous analytes in the field has become increasingly important. One of the most important analytical detection methods in the field is gas chromatography-mass spectrometry (GC-MS). In this work, a hand-portable GC-MS system is described that contains a miniature toroidal ion trap mass analyzer and a low thermal mass GC. The system is self-contained within the dimensions of 47 x 36 x 18 cm and weighs less than 13 kg. Because the instrument has a small footprint, it was used as the detector for an automated near-real-time permeation testing system. In permeation testing, materials that are used to make individual protective equipment such as gloves, masks, boots, and suits are exposed to hazardous analytes to determine how long the equipment can be worn safely. The system described herein could test five samples simultaneously. A multi-position valve rotated among the various sample streams and delivered time aliquots into the MS for quantitation. Current field air sampling techniques suffer from long desorption times, high pressure drops, artifact formation and water retention. These disadvantages can be avoided by concentrating the analytes in short open tubular traps containing thick films. There are several advantages to using polymer coated capillaries as traps, including fast desorption, inertness and low flow restriction. An air sampling trap was constructed utilizing open tubular traps for the concentration of semi-volatile organic compounds. The system consisted of multiple capillary traps bundled together, providing high sample flow rates. The analytes were desorbed from the multi-capillary bundle and refocused in a secondary trap. The simultaneous focusing and separation effect of a trap subjected to a negative temperature gradient was also explored. In this configuration, analytes were focused because the front of the peak was at a lower temperature than the rear of the peak and, hence, moved slower. In addition to the focusing effect, analytes with different volatilities focused at different temperatures within the gradient, allowing for separation.
9
Rheinberg, Falko, Regina Vollmeyer, and Stefan Engeser. "Die Erfassung des Flow-Erlebens." Universität Potsdam, 2003. http://opus.kobv.de/ubp/volltexte/2006/634/.
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Ausgehend von einer Charakterisierung des Flow-Erlebens als gaenzliches Aufgehen in einem glatt laufenden Taetigkeitsvollzug, den man trotz hoher Beanspruchung noch unter Kontrolle hat, wird auf die Erfassung dieser Motivationskomponente eingegangen. Dargestellt und diskutiert werden Vor- und Nachteile der bisherigen qualitativen (Interviews) und quantitativen Flow-Erfassung (Experience Sampling Method (ESM)) . Ausfuehrlicher wird eine "Flow-Kurzskala" (FKS) beschrieben, die mit zehn Items alle qualitativ verschiedenen Komponenten des Flow-Erlebens oekonomisch und reliabel erfasst. Sie liefert einen Gesamtwert sowie Werte fuer zwei Subskalen (glatter automatisierter Verlauf sowie Absorbiertheit). Daneben erfassen drei zusaetzliche Items die Besorgnis in der aktuellen Situation. Berichtet werden Vergleichskennwerte aus punktuellen Messungen und ESM-Studien. Die hoechsten Werte fuer Flow und Besorgnis wurden bislang bei Graffiti-Sprayern gefunden. Bei einer intellektuell herausfordernden Aufgabe (Postkorbuebung) sind die FKS-Werte mit der Hoffnung-auf-Erfolg-Komponente des Leistungsmotivs korreliert. Furcht-vor-Misserfolg korreliert dagegen mit dem Besorgniswert der FKS. Flow waehrend der Bearbeitung von Uebungsaufgaben fuer Statistik lieferte einen signifikanten Beitrag zur Vorhersage der nachfolgenden Klausurleistung. Dieser Beitrag blieb erhalten, auch wenn Faehigkeitsmasse kontrolliert wurden. (Buch/A.G. - ZPID)
10
Singh, Rohitendra Kumar. "A study of air flow in a network of pipes used in aspirated smoke detectors." full-text, 2009. http://eprints.vu.edu.au/15172.
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Thesis (M. Eng.)--Victoria University (Melbourne, Vic.), 2009.<br>Submitted in fulfilment of the requirements for the degree of Master of Engineering in Mechanical Engineering. Includes bibliographical references.
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Vijayaraghavan, Vishnu Karthik. "Numerical modeling of species transport in turbulent flow and experimental study on aerosol sampling." Texas A&M University, 2006. http://hdl.handle.net/1969.1/4902.
Full textAbstract:
Numerical simulations were performed to study the turbulent mixing of a scalar
species in straight tube, single and double elbow flow configurations. Different Reynolds
Averaged Navier Stokes (RANS) and Large Eddy Simulation (LES) models were used
to model the turbulence in the flow. Conventional and dynamic Smagorinsky sub-grid
scale models were used for the LES simulations. Wall functions were used to resolve the
near wall boundary layer. These simulations were run with both two-dimensional and
three-dimensional geometries. The velocity and tracer gas concentration Coefficient of
Variations were compared with experimental results. The results from the LES
simulations compared better with experimental results than the results from the RANS
simulations. The level of mixing downstream of a S-shaped double elbow was higher
than either the single elbow or the U-shaped double elbow due to the presence of counter
rotating vortices. Penetration of neutralized and non-neutralized aerosol particles
through three different types of tubing was studied. The tubing used included standard
PVC pipes, aluminum conduit and flexible vacuum hose. Penetration through the aluminum conduit was unaffected by the presence or absence of charge neutralization,
whereas particle penetrations through the PVC pipe and the flexible hosing were
affected by the amount of particle charge. The electric field in a space enclosed by a
solid conductor is zero. Therefore charged particles within the conducting aluminum
conduit do not experience any force due to ambient electric fields, whereas the charged
particles within the non-conducting PVC pipe and flexible hose experience forces due to
the ambient electric fields. This increases the deposition of charged particles compared
to neutralized particles within the 1.5â PVC tube and 1.5â flexible hose. Deposition
2001a (McFarland et al. 2001) software was used to predict the penetration through
transport lines. The prediction from the software compared well with experiments for all
cases except when charged particles were transported through non-conducting materials.
A Stairmand cyclone was designed for filtering out large particles at the entrance of the
transport section.
12
Ernst, Michael Jules 1960. "Modeling multicomponent vacuum flow, transport, and outgassing in a membrane-inlet vapor sampling probe." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/36502.
Full textAbstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 1994.<br>Vita.<br>Includes bibliographical references (p. 341-345).<br>by Michael Jules Ernst.<br>Ph.D.
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Mohamed, Lina Mahgoub Yahya. "Novel sampling techniques for reservoir history matching optimisation and uncertainty quantification in flow prediction." Thesis, Heriot-Watt University, 2011. http://hdl.handle.net/10399/2435.
Full textAbstract:
Modern reservoir management has an increasing focus on accurately predicting the likely range of field recoveries. A variety of assisted history matching techniques has been developed across the research community concerned with this topic. These techniques are based on obtaining multiple models that closely reproduce the historical flow behaviour of a reservoir. The set of resulted history matched models is then used to quantify uncertainty in predicting the future performance of the reservoir and providing economic evaluations for different field development strategies. The key step in this workflow is to employ algorithms that sample the parameter space in an efficient but appropriate manner. The algorithm choice has an impact on how fast a model is obtained and how well the model fits the production data. The sampling techniques that have been developed to date include, among others, gradient based methods, evolutionary algorithms, and ensemble Kalman filter (EnKF). This thesis has investigated and further developed the following sampling and inference techniques: Particle Swarm Optimisation (PSO), Hamiltonian Monte Carlo, and Population Markov Chain Monte Carlo. The inspected techniques have the capability of navigating the parameter space and producing history matched models that can be used to quantify the uncertainty in the forecasts in a faster and more reliable way. The analysis of these techniques, compared with Neighbourhood Algorithm (NA), has shown how the different techniques affect the predicted recovery from petroleum systems and the benefits of the developed methods over the NA. The history matching problem is multi-objective in nature, with the production data possibly consisting of multiple types, coming from different wells, and collected at different times. Multiple objectives can be constructed from these data and explicitly be optimised in the multi-objective scheme. The thesis has extended the PSO to handle multi-objective history matching problems in which a number of possible conflicting objectives must be satisfied simultaneously. The benefits and efficiency of innovative multi-objective particle swarm scheme (MOPSO) are demonstrated for synthetic reservoirs. It is demonstrated that the MOPSO procedure can provide a substantial improvement in finding a diverse set of good fitting models with a fewer number of very costly forward simulations runs than the standard single objective case, depending on how the objectives are constructed. The thesis has also shown how to tackle a large number of unknown parameters through the coupling of high performance global optimisation algorithms, such as PSO, with model reduction techniques such as kernel principal component analysis (PCA), for parameterising spatially correlated random fields. The results of the PSO-PCA coupling applied to a recent SPE benchmark history matching problem have demonstrated that the approach is indeed applicable for practical problems. A comparison of PSO with the EnKF data assimilation method has been carried out and has concluded that both methods have obtained comparable results on the example case. This point reinforces the need for using a range of assisted history matching algorithms for more confidence in predictions.
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Newsome, Eve. "An Investigation of the Effectiveness of Flow Teaching on Instrumental Practice and Performance." Thesis, Griffith University, 2022. http://hdl.handle.net/10072/413021.
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This study investigated the effectiveness of flow teaching as directed to the practice and performance of instrumental music in the post-secondary context. Its purpose was to determine the effectiveness of a three-lesson educational flow intervention for twelve post-secondary brass and string instrumentalists. Data were collected through measures of subjective experience during practice and performance and the objective assessment of three performances.
Flow experiences have been studied extensively in sport since the 1970s, and consequently, training strategies have been developed to increase flow levels in sporting contexts to maximise the possibility of optimal experience. However, in the domain of instrumental music, flow training strategies have not been thoroughly developed, researched, or applied for practice or performance purposes. Therefore, it is not known what potential effects, if any, applied flow theory strategies might have on instrumental practice and performance experiences or performance outcomes.
The study employed a mixed method approach using recognised qualitative and quantitative methods suitable for an educational intervention research investigation. The methodology was a quasi-experimental intervention with non-equivalent control using concurrent triangulation comparative mixed method design. This provided the simplest form of baseline design with two groups and allowed each group to act as both an intervention group and a control group maximising the possible data collection for the small sample and short timeframe.
The participants in the study were 12 self-selected undergraduate string and brass players from the Bachelor of Music course at the Queensland Conservatorium Griffith University (QCGU), Australia. They were stratified and randomly assigned into two groups of six. During the Intervention phases of the 38-day study, each participant received three one-to-one Flow Music Method (FMM) lessons created by the researcher. The FMM was based on the work of psychologist Mihalyi Csikszentmihalyi and other flow researchers.
Across the timeline of the study, participants completed an experience sampling form (ESF) to measure the details of their subjective experience during each practice session and immediately after performances. In addition, a video journal was recorded at the end of each practice session and a post-study interview completed. At the end of the study, an expert panel of two music assessors rated the level of performances of each participant in randomised order using a Performance Assessment Form compiled by the researcher for that purpose.
All data were analysed using SPSS and NVivo to ascertain the effects of the FMM Intervention on the participant experience of practice and performance and to examine the rater assessment of performances. An investigation of the relationships between practice and performance experience and rater assessment was subsequently undertaken to determine any relevant findings. Results showed that the experience of participants during instrumental practice became more positive for both groups in terms of Mood, Flow, Last 5 minutes of practice, and Overall experience from Phase 1 to Phase 2 across the timeline of the study with effect sizes ranging from small to very large. Findings also revealed that the experience of participants during instrumental performance became more positive with higher levels of Mood, Flow, Last 5 minutes of performance, and Overall experience found in both groups for the performance immediately after the Intervention when compared with the baseline performance. The greatest increases were found for Group 1 for the scales of Flow and Last 5 where there were statistically significant and very large effects. These findings provided support for the positive effect of the FMM Intervention on the practice and performance experience of both groups.The analysis of the objective ratings of performances by two expert raters showed sufficient correlation of the global scores, however, no conclusions could be made concerning the relationship of the global scores with the practice and performance experience of participants. It is recommended that further studies of a similar nature be conducted to facilitate a deeper understanding of the relationship between the subjective response of the participants and the objective assessment of their performance. In addition, it is proposed that the FMM be adapted to ameliorate any identified challenges and to enable the most effective application to instrumental pedagogic contexts in future.<br>Thesis (PhD Doctorate)<br>Doctor of Philosophy (PhD)<br>Queensland Conservatorium<br>Arts, Education and Law<br>Full Text
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Pfister, Regula. "Flow im Alltag : Untersuchungen zum Quadrantenmodell des Flow-Erlebens und zum Konzept der autotelischen Persönlichkeit mit der Experience sampling method (ESM) /." Bern : P. Lang, 2002. http://catalogue.bnf.fr/ark:/12148/cb39109437d.
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Ziegenhein, Thomas, and Dirk Lucas. "On sampling bias in multiphase flows: Particle image velocimetry in bubbly flows." Helmholtz-Zentrum Dresden - Rossendorf, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:d120-qucosa-197551.
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Measuring the liquid velocity and turbulence parameters in multiphase flows is a challenging task. In general, measurements based on optical methods are hindered by the presence of the gas phase. In the present work, it is shown that this leads to a sampling bias. Here, particle image velocimetry (PIV) is used to measure the liquid velocity and turbulence in a bubble column for different gas volume flow rates. As a result, passing bubbles lead to a significant sampling bias, which is evaluated by the mean liquid velocity and Reynolds stress tensor components. To overcome the sampling bias a window averaging procedure that waits a time depending on the locally distributed velocity information (hold processor) is derived. The procedure is demonstrated for an analytical test function. The PIV results obtained with the hold processor are reasonable for all values. By using the new procedure, reliable liquid velocity measurements in bubbly flows, which are vitally needed for CFD validation and modeling, are possible. In addition, the findings are general and can be applied to other flow situations and measuring techniques.
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Abili, Nimi Inko. "Subsea fluid sampling to maximise production asset in offshore field development." Thesis, Cranfield University, 2015. http://dspace.lib.cranfield.ac.uk/handle/1826/10017.
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The acquisition of representative subsea fluid sampling from offshore field development asset is crucial for the correct evaluation of oil reserves and for the design of subsea production facilities. Due to rising operational expenditures, operators and manufacturers have been working hard to provide systems to enable cost effective subsea fluid sampling solutions. To achieve this, any system has to collect sufficient sample volumes to ensure statistically valid characterisation of the sampled fluids. In executing the research project, various subsea sampling methods used in the offshore industry were examined and ranked using multi criteria decision making; a solution using a remote operated vehicle was selected as the preferred method, to compliment the subsea multiphase flowmeter capability, used to provide well diagnostics to measure individual phases – oil, gas, and water. A mechanistic (compositional fluid tracking) model is employed, using the fluid properties that are equivalent to the production flow stream being measured, to predict reliable reservoir fluid characteristics on the subsea production system. This is applicable even under conditions where significant variations in the reservoir fluid composition occur in transient production operations. The model also adds value in the decision to employ subsea processing in managing water breakthrough as the field matures. This can be achieved through efficient processing of the fluid with separation and boosting delivered to the topside facilities or for water re-injection to the reservoir. The combination of multiphase flowmeter, remote operated vehicle deployed fluid sampling and the mechanistic model provides a balanced approach to reservoir performance monitoring. Therefore, regular and systematic field tailored application of subsea fluid sampling should provide detailed understanding on formation fluid, a basis for accurate prediction of reservoir fluid characteristic, to maximize well production in offshore field development.
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Giovannini, Luca <1982>. "A novel map-matching procedure for low-sampling GPS data with applications to traffic flow analysis." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2011. http://amsdottorato.unibo.it/3898/1/giovannini_luca_tesi.pdf.
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An extensive sample (2%) of private vehicles in Italy are equipped with a GPS device that periodically measures their position and dynamical state for insurance purposes. Having access to this type of data allows to develop theoretical and practical applications of great interest: the real-time reconstruction of traffic state in a certain region, the development of accurate models of vehicle dynamics, the study of the cognitive dynamics of drivers.
In order for these applications to be possible, we first need to develop the ability to reconstruct the paths taken by vehicles on the road network from the raw GPS data. In fact, these data are affected by positioning errors and they are often very distanced from each other (~2 Km). For these reasons, the task of path identification is not straightforward.
This thesis describes the approach we followed to reliably identify vehicle paths from this kind of low-sampling data.
The problem of matching data with roads is solved with a bayesian approach of maximum likelihood. While the identification of the path taken between two consecutive GPS measures is performed with a specifically developed optimal routing algorithm, based on A* algorithm. The procedure was applied on an off-line urban data sample and proved to be robust and accurate. Future developments will extend the procedure to real-time execution and nation-wide coverage.
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Giovannini, Luca <1982>. "A novel map-matching procedure for low-sampling GPS data with applications to traffic flow analysis." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2011. http://amsdottorato.unibo.it/3898/.
Full textAbstract:
An extensive sample (2%) of private vehicles in Italy are equipped with a GPS device that periodically measures their position and dynamical state for insurance purposes. Having access to this type of data allows to develop theoretical and practical applications of great interest: the real-time reconstruction of traffic state in a certain region, the development of accurate models of vehicle dynamics, the study of the cognitive dynamics of drivers.
In order for these applications to be possible, we first need to develop the ability to reconstruct the paths taken by vehicles on the road network from the raw GPS data. In fact, these data are affected by positioning errors and they are often very distanced from each other (~2 Km). For these reasons, the task of path identification is not straightforward.
This thesis describes the approach we followed to reliably identify vehicle paths from this kind of low-sampling data.
The problem of matching data with roads is solved with a bayesian approach of maximum likelihood. While the identification of the path taken between two consecutive GPS measures is performed with a specifically developed optimal routing algorithm, based on A* algorithm. The procedure was applied on an off-line urban data sample and proved to be robust and accurate. Future developments will extend the procedure to real-time execution and nation-wide coverage.
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Fontaine, Charles P. "A NOVEL CHALLENGE OF THE LAMINAR FLOW BIOLOGICAL SAFETY CABINET USING PCR." Ohio University / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1143465053.
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Hansson, Mattias. "Macroinvertebrate sampling in hydropeaking rivers : Testing Hester-Dendy samplers in a laboratory environment using different flow conditions." Thesis, Karlstads universitet, Avdelningen för biologi, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-78552.
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Degraded rivers and streams caused by disturbances have created a need for reliable tools to assess the ecological status of such ecosystems. Numerous methods and programs have been developed to assess ecological status using biological indicators, benthic macroinvertebrates are the most commonly used biotic indicator. The Hester-Dendy multi-plate sampler is a commonly used tool for sampling benthic macroinvertebrates, but its effectiveness under different environmental conditions has not been adequately tested. The aim of this study was to investigate if HD samplers assess the benthic macroinvertebrate community equally under different flow conditions. I investigated if the colonization of BMI in a constant flow differed from that of a variable flow (simulating a hydropeaking flow regime). This was studied using six aquariums, three as control with constant flows and three with variable flow conditions. One Hester-Dendy sampler and 50 benthic macro invertebrates from five different taxonomic orders were place in each aquarium. After five days of colonization the Hester-Dendy samplers were retrieved and benthic macroinvertebrates colonizing the Hester-Dendy samplers and still remaining in the aquariums were collected, preserved and analysed. Results showed that the mean sampling efficiency did not differ between the two treatments. On the other hand species diversity calculated from Shannon-Wiener index was significantly higher in the control treatment than in the variable flow treatment. The lower species diversity in the variable flow treatment is consistent with previous research on benthic macroinvertebrates affected by hydropeaking powerplants. These results can be seen as an indication of how a variable flow regime might affect the samples collected by HD samplers in a natural environment. As the artificial environments created are greatly different from a natural environment, this result might not therefore be representative in a natural environment.<br>Vattendrag kraftigt påverkade av antropogena störningarna har skapat ett behov av tillförlitliga verktyg för att kunna bedöma dessa vattendrags ekologiska status. Många olika metoder och program har utvecklats genom att använda olika biologiska indikatorer. Bentiska makroevertebrater är en av de vanligaste biotiska indikatorerna. En vanlig metod för att prov ta bentiska makroevertebrater är Hester-Dendy provtagaren. Syftet med denna studie var således att testa om provtagningseffektiviteten för Hester-Dendy provtagare påverkas olika av ett variabelt vattenflöde jämfört med ett jämnt vattenflöde. Detta studerades i sex akvarium, där tre akvarium agerade kontroll och utsattes för ett jämt flöde samt tre akvarium med variabelt flöde. En Hester-Dendy provtagare och 50 bentiska makroevertebrater från fem olika taxonomiska ordningar placerades i varje akvarium. Efter fem dagars koloniserings tid hämtades Hester-Dendy provtagarna och de bentiska makroevertebrater som koloniserade provtagaren såväl som akvariet bevarades i etanol och analyserades i labbet. Resultaten visade att den genomsnittliga provtagningseffektiviteten inte skilde sig åt mellan de två behandlingarna. Däremot var artdiversiteten beräknad med Shannon-Wiener-index signifikant högre i kontrollbehandlingen. Den lägre artdiversiteten i behandlingen med variabelt flöde stämmer överens med tidigare forskning om bentiska makroevertebrater påverkade av korttidsreglerande vattenkraftverk. Resultaten i denna studie bör ses som en indikation av hur ett varierande flöde kan påverka provtagnings effektiviteten hos en Hester-Dendy-provtagare. Detta med anledning av att den konstgjorda miljön som försöket utfördes i är vitt skilt från organismernas naturliga miljö vilket kan ha påverkat resultatet.
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Yang, Yihong. "Experimental Study of Multi-phase Flow Hydrodynamics in Stirring Tanks." Diss., Virginia Tech, 2011. http://hdl.handle.net/10919/77056.
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Stirring tanks are very important equipments used for mixing, separating, chemical reaction, etc. A typical stirring tank is a cylindrical vessel with an agitator driving the fluid and generating turbulence to promote mixing. Flotation cells are widely used stirring tanks in phase separation where multiphase flow is involved. Flotation refers to the process in which air bubbles selectively pick up hydrophobic particles and separate them from hydrophilic solids. This technology is used throughout the mining industry as well as the chemical and petroleum industries.
In this research, efforts were made to investigate the multi-phase flow hydrodynamic problems of some flotation cells at different geometrical scales. Pitot-static and five-hope probes were employed to lab- pilot- and commercial-scale tanks for velocity measurements. It was found that the tanks with different scales have similar flow patterns over a range of Reynolds numbers. Based on the velocity measurement results, flotation tanks' performance was evaluated by checking the active volume in the bulk. A fast-response five-hole probe was designed and fabricated to study the turbulence characteristics in flotation cells under single- and multi-phase flow conditions. The jet stream in the rotor-stator domain has much higher turbulence intensity compared with other locations. The turbulent dissipation rate (TDR) in the rotor-stator domain is around 20 times higher than that near tank's wall. The TDR could be used to calculate the bubble and particle slip velocities. An isokinetic sampling probe system was developed to obtain true samples inthe multi-phase flow and then measure the local void fraction. It was found that the air bubbles are carried out by the stream and dispersed to the whole bulk. However, some of the bubbles accumulate in the inactive regions, where higher void fractions were detected. The isokinetic sampling probe was then extended to be an isokinetic borescope system, which was used to detect the bubble-particle aggregates in the tank. Aggregates were found in the high-turbulence level zones. The isokinetic sampling probe and the isokinetic borescope provide new methods for flotation tank tests. An experiment was also set up to study the dynamics of bubble particle impact. Four different modes were found for the collision. The criterion is that if the fluid drainage time is less than the residence time, the attachment will occur, otherwise, the particle will bounce back.<br>Ph. D.
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El-Nahas, Waleed Mahmoud. "Effects of heating, breathing, hair style, posture, and air velocity on breathing zone concentrations for an anthropometrically-correct manikin in a wind tunnel." Morgantown, W. Va. : [West Virginia University Libraries], 2005. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=4274.
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Thesis (Ph. D.)--West Virginia University, 2005.<br>Title from document title page. Document formatted into pages; contains xiv, 256 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 118-122).
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Ross, Robert L. "Taking It Down a Level: Low Flow Sampling of RNAs by Liquid Chromatography Coupled to Tandem Mass Spectrometry." University of Cincinnati / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1470757778.
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Pajic, Slobodan. "Power System State Estimation and Contingency Constrained Optimal Power Flow - A Numerically Robust Implementation." Digital WPI, 2007. https://digitalcommons.wpi.edu/etd-dissertations/240.
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The research conducted in this dissertation is divided into two main parts. The first part provides further improvements in power system state estimation and the second part implements Contingency Constrained Optimal Power Flow (CCOPF) in a stochastic multiple contingency framework. As a real-time application in modern power systems, the existing Newton-QR state estimation algorithms are too slow and too fragile numerically. This dissertation presents a new and more robust method that is based on trust region techniques. A faster method was found among the class of Krylov subspace iterative methods, a robust implementation of the conjugate gradient method, called the LSQR method. Both algorithms have been tested against the widely used Newton-QR state estimator on the standard IEEE test networks. The trust region method-based state estimator was found to be very reliable under severe conditions (bad data, topological and parameter errors). This enhanced reliability justifies the additional time and computational effort required for its execution. The numerical simulations indicate that the iterative Newton-LSQR method is competitive in robustness with classical direct Newton-QR. The gain in computational efficiency has not come at the cost of solution reliability. The second part of the dissertation combines Sequential Quadratic Programming (SQP)-based CCOPF with Monte Carlo importance sampling to estimate the operating cost of multiple contingencies. We also developed an LP-based formulation for the CCOPF that can efficiently calculate Locational Marginal Prices (LMPs) under multiple contingencies. Based on Monte Carlo importance sampling idea, the proposed algorithm can stochastically assess the impact of multiple contingencies on LMP-congestion prices.
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Bromley, II Michael William. "Pneumatic Particulate Collection System Analysis and Design." Thesis, Virginia Tech, 2012. http://hdl.handle.net/10919/33562.
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A pneumatic particulate collection system harnesses the energy associated with the release of a compressed gas to transport particulate to a collection chamber. In an effort to improve the efficiency of a previously designed collection system, high speed imaging in conjunction with computational fluid dynamics (CFD) was utilized to highlight design deficiencies. Areas of recirculation within the collection device as well as impingement of the sampling surface were observed through the testing and CFD analysis. The basis of the improved collection system was conceived through research of pneumatic transport and the deficiencies found through testing and simulation. An improved rectangular-duct-styled system was designed in three main stages. A variety of filters used to contain the desired particulate were characterized through testing for use in simulations as well as fluids calculations. The improved system was then analyzed utilizing compressible and incompressible flow calculations and design iterations were conducted with CFD to determine the final parameters. The final design was simulated with a multiphase flow model to examine the particulate entrainment performance. The improved collection system efficiently expanded and developed the gas flow prior to the collection area to employ the particulate entrainment process. The final design was constructed with an additive manufacturing process and experimentally tested to validate the simulations and flow calculations. The testing proved that the final design operated purely on particulate entrainment and collected only the top layer of particles as simulated. The improved collection system eliminated all areas of flow recirculation and impingement of the particle bed to provide a more efficient sampling device.<br>Master of Science
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Bringsén, Åsa, Göran Ejlertsson, and H. Ingemar Andersson. "Flow situations during everyday practice in a medical hospital ward : results from a study based on experience sampling method." Högskolan Kristianstad, Sektionen för hälsa och samhälle, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:hkr:diva-8813.
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Nursing is a constant balance between strain and stimulation and work and health research with a positive reference point has been recommended. A health-promoting circumstance for subjective experience is flow, which is a psychological state, when individuals concurrently experience happiness, motivation and cognitive efficiency. Flow situations can be identified through individuals' estimates of perceived challenge and skills. There is, to the best of our knowledge, no published study of flow among health care staff. The aim of this study was to identify flow-situations and study work-related activities and individual factors associated with flow situations, during everyday practice at a medical emergency ward in Sweden, in order to increase the knowledge on salutogenic health-promoting factors.The respondents consisted of 17 assistant nurses and 14 registered nurses, who randomly and repeatedly answered a small questionnaire, through an experience sampling method, during everyday nursing practice. The study resulted in 497 observations. Flow situations were defined as an exact match between a high challenge and skill estimation and logistic regression models were used to study different variables association to flow situations.The health care staff spent most of its working time in individual nursing care and administrative and communicative duties. The assistant nurses were more often occupied in individual nursing care, while the registered nurses were more involved in medical care and administrative and communicative duties. The study resulted in 11.5% observations of flow situations but the relative number of flow situations varied between none to 55% among the participants. Flow situations were positively related to medical care activities and individual cognitive resources. Taking a break was also positively associated with flow situations among the assistant nurses.The result showed opportunities for work-related interventions, with an adherent increase in flow situations, opportunity for experience of flow and work-related health among the nursing staff in general and among the assistant nurses in particular.
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Graves, Alexandria Kristen. "Identifying Sources of Fecal Pollution in Water as Function of Sampling Frequency Under Low and High Stream Flow Conditions." Diss., Virginia Tech, 2003. http://hdl.handle.net/10919/27162.
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Sources of fecal pollution were evaluated as a function of sampling frequency with stream samples from Mill Creek, Montgomery County, VA. Samples were collected monthly for one year, plus weekly for four consecutive weeks during seasonal high flows (March), and seasonal low flows (September-October), plus daily for seven consecutive days within the weekly schedules. Thirty stream samples were collected from each of two sites (60 total) in Mill Creek, and 48 isolates of E. coli per sample (total of 2,880 stream isolates) were classified by source using antibiotic resistance analysis (ARA) and comparing the resulting patterns against a known-source E. coli library (1,158 isolates). The same process was performed with enterococci isolates against an enterococci library (1,182 isolates). The average rate of correct classification (ARCC) for the E. coli library with a three-way split (human, livestock, and wildlife) was 89.0%, and the ARCC of the species-specific E. coli library (cattle, deer, goose, human, misc. wildlife) was 88.9%. The ARCC of the enterococci library with a three-way split was 85.3%, and the ARCC of the species-specific enterococci library was 88.1%. The results did not justify the need for daily or weekly sampling, but indicated that monthly was adequate (quarterly and every-other-month were not). There was a seasonal effect as the human signature was highest during high flow while the livestock signature dominated during low flow. The results also indicated that sampling should be done over a period of time that includes both seasonal wettest and driest periods (at least 8 months).<br>Ph. D.
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Scicluna, Helen. "An analysis of the relationship between mood states, sense of self, flow and personal constructs in anorexia nervosa participants." University of Sydney. Psychological Medicine, 2001. http://hdl.handle.net/2123/836.
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Public view removed at the authors request. 16/07/2006<br>The daily experience of anorexia nervosa sufferers has not previously been studied and yet it is fundamental to understanding anorexia nervosa. This study examined and compared the daily experiences of anorexia nervosa patients and control participants in terms of sense of self, mood states and flow states. Flow is characterised by undivided concentration and interest in an activity for intrinsic benefits. Flow is not always desirable, as some ways of experiencing it may be harmful to the individual and society. Anorexia nervosa participants were recruited from hospitals and private practices of clinicians specialising in the treatment of anorexia nervosa. Exclusion criteria included male gender, chronic anorexia nervosa, drug abuse, and current participation in an inpatient program. Anorexia nervosa participants completed a series of questionnaires at baseline, 3-6 month follow-up and 7-12 month follow-up (stage one, two and three respectively). The questionnaires were designed to measure the severity of their eating disorder. Anorexia nervosa and control group participants completed Experience Sampling Forms (ESF) and a Repertory Grid at baseline and 3-6 months. The ESFs were completed each time a pager was activated. The pager was activated seven times a day, for four days at random times between 8.00am and 10.00pm. The pager signals were a minimum of two hours apart. The Repertory Grid consisted of 23 constructs and 13 elements provided to the participant. Thirty-one anorexia nervosa sufferers and thirty-two control participants completed stage one and eighteen anorexia nervosa sufferers and twenty-seven control group participants completed stage two of the study. Eighteen anorexia nervosa sufferers completed stage three of the study. Control participants were not required to participate in stage three. There was no difference in the severity of anorexia nervosa between completers and drop-outs The analysis of the ESFs at stage one indicated that the anorexia nervosa group participants did not spend more time alone at home or more time alone in any situation than the control group. For both groups, being alone had a negative influence on mood state, but had no effect on sense of self. The anorexia nervosa group felt lonelier and less sociable than the control group. The mood state and sense of self for the anorexia nervosa group was significantly lower over all the ESFs when compared to the control group. They were also more self-critical, experienced higher levels of guilt, were less able to live up to their own expectations, and were less satisfied with their performance in the activity they were doing. The anorexia nervosa group experienced less flow states than the control group at stage one. There was an improvement in mood state, sense of self and self-criticism for the anorexia nervosa group when they were in a flow state compared to when they were not in a flow state. There was an improvement in mood state, sense of self, guilt and self-criticism for the control group when they experienced flow, however these differences were not significant. The anorexia nervosa group had a more positive mood state and sense of self at stage two when compared to stage one. Correspondingly, there was a trend towards a reduced severity of the disorder indicated by a significant improvement on some of the psychological tests (EAT, REDS, BDI, DT). There was also a significant improvement in BMI. However, there was a significant decline in the amount of flow of anorexia nervosa participants experienced at stage two when compared to stage one. This result may be attributed to the significant decline in the response rate on ESFs in the second stage of the study for both the anorexia nervosa and control groups. Anorexia nervosa non-responders at stage two reported more severe symptoms of anorexia nervosa than anorexia nervosa responders, although this was a trend and reached significance only on minor indicators of eating disorder severity. The identification of a factor that predicted severity over a six-month period was not possible. The repertory grid analysis showed that the construct system of the anorexia nervosa participants was tighter and less complex than that of the control group. The anorexia nervosa group construed themselves as dissimilar from the way they would like to be in any context. The control group construed themselves as similar to the way they would like to be when they were alone, but as dissimilar from the way they would like to be when they were with other people. While the most salient element for both the anorexia nervosa and control groups was 'alone at home', it appears that the controls use this time for goal-directed activities. In contrast, this time was dominated by fear of losing control for the anorexia nervosa group. Although there was a trend towards a decrease in the amount of variance accounted for by the first component for the anorexia nervosa group at stage two compared to stage one, the interpretation of this result was complicated by mixed result of the control group. The anorexia nervosa groups' daily experience of life was bleak when compared to the daily experience of the control group, except for periods when the anorexia nervosa participants experienced a flow state. DeVries (1992) has documented the success of therapeutic interventions that involve the identification and replication of activities that resulted in a flow state. This investigation suggests that a similar result may be possible in the treatment of anorexia nervosa.
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Renken, Hendrik [Verfasser]. "Acceleration of material flow simulations : using model coarsening by token sampling and online error estimation and accumulation controlling / Hendrik Renken." Paderborn : Universitätsbibliothek, 2014. http://d-nb.info/1077049714/34.
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Menuchi, Marcos Rodrigo Trindade Pinheiro. "Locomoção visualmente guiada na transposição de obstáculos : efeitos de amostras visuais estáticas e dinâmica /." Rio Claro : [s.n.], 2005. http://hdl.handle.net/11449/87418.
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Orientador: Lilian Teresa Bucken Gobbi<br>Banca: José Angelo Barela<br>Banca: Sérgio Teixeira Fonseca<br>Resumo: Durante a locomoção, ocorre um padrão de movimento visual referido como um campo de fluxo óptico. Para explorar como os ajustamentos locomotores são influenciados por este padrão, um paradigma experimental foi desenvolvido para anular o fluxo óptico durante a locomoção e ultrapassagem de obstáculo. O objetivo deste estudo foi investigar a contribuição de amostragens visuais estáticas e dinâmica na locomoção e ultrapassagem de obstáculos de diferentes alturas. Dez indivíduos (23,4 l 1,28 anos de idade, de ambos os gêneros) foram convidados a andar sobre uma passarela e ultrapassar um de dois obstáculos personalizados (obstáculo alto = altura do joelho e obstáculo baixo = altura do tornozelo) posicionado a 5m do ponto de partida. Diodos emissores de luz foram afixados no 5º metatarso e face lateral do calcâneo em ambos os pés e suas trajetórias foram filmados por quatro filmadoras digitais posicionadas bilateralmente à passarela. Dois blocos de tentativas foram apresentados em função das condições de amostragens visuais. No primeiro bloco, 10 tentativas com amostragem visual dinâmica (iluminação normal) foram apresentadas. No segundo bloco de tentativas, duas condições de amostragens visuais estáticas foram apresentadas de forma aleatória por meio de uma luz estroboscópica (2 flashes/segundo e 4 flashes/segundo). A duração de cada flash não ultrapassou 16ms e forneceu apenas imagens estáticas do ambiente. A altura do obstáculo foi randomizada em cada bloco de tentativas. Cinco tentativas para cada condição foram coletadas, totalizando 30 tentativas por participante. Todas as imagens foram digitalizadas e reconstruídas no plano tri-dimensional. As variáveis dependentes na fase de aproximação (comprimentos dos dois passos anteriores à ultrapassagem) e na fase de ultrapassagem... (Resumo completo, clicar acesso eletrônico abaixo)<br>Abstract: During locomotion, a pattern of visual motion referred as an optic flow field occurs. In order to explore how the locomotor adjustments are influenced by this pattern, an experimental paradigm was developed to remove the optic flow during locomotion and obstacle avoidance. The aim of this study was to investigate the contribution of the static and dynamic visual sampling on the locomotion and obstacle avoidance of different heights. Ten individuals (23.4 l 1.28 years of age, both genders) were invited to walk on a pathway and to avoid one out of two personalized obstacles (high obstacle = knee height and low obstacle = ankle height) positioned 5m from the starting position. Light emitting diodes were fixed on the fifth metatarsal and calcaneus lateral face in both feet and their trajectories were recorded by four digital cameras bilaterally positioned related to the pathway. Two trial blocks were presented depending of the visual sampling conditions. In the first block, 10 trials with visual dynamic sampling (normal light) were presented. In the second trial block, two conditions of the static visual sampling frequencies were presented in an randomized way by means of the stroboscopic light (2 flashes/second or 4 flashes/second). Each flash duration was about 16ms and provided only environmental static images. Obstacle height was randomized for each trial block. Five trials for each experimental condition were collected totalizing 30 trials for each participant. All images were digitalized and reconstructed in the 3D plane. Dependent variables in the approach phase (last two step lengths before crossing) and in the crossing phase (horizontal toe distance to the obstacle prior crossing, obstacle toe clearance and mean horizontal velocity for each foot) were selected. The results revealed differences... (Complete abstract, access undermentioned electronic address)<br>Mestre
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Bekkouche, Abdelmalek. "Sécurité des grands barrages en terre : approche probabiliste des problèmes d'écoulement liés aux reconnaissances et contrôles." Châtenay-Malabry, Ecole centrale de Paris, 1987. http://www.theses.fr/1987ECAP0038.
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Etude de l'état critique d'érosion interne des grands barrages (données du barrage de grand' maison) : percolation interne, résistance à l'érosion. Problèmes de contrôle de l'homogénéité du noyau (matériau et compactage): application de l'analyse factorielle, optimisation du nombre d'essais de cisaillement par l'analyse de variance-covariance et l'estimation bayesienne ; possibilités de calcul de performance par éléments finis stochastiques.
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Dahlstrom, Erik A. "An Examination of Arousal States in Novice Whitewater Kayakers During a Weekend Instructional Experience." Ohio University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1213027065.
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Gillefalk, Mikael, and Felix Lindberg. "Sediment State and Flow – An Investigation of Sediment Pollution and Transport in the Bîc River, Republic of Moldova. : A Minor Field Study." Thesis, KTH, Mark- och vattenteknik (flyttat 20130630), 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-171825.
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The Bîc River in the Republic of Moldova is a heavily polluted water body. Along the river stretch, from a small creek in Sipoteni close to the river mouth at Gura Bîcului, sediment samples were taken using a very cost-effective method and analyzed for a number of pollutants. The results showed very high levels of petroleum products in and downstream of the city of Chişinău, situated in the middle of the river basin, ex-ceeding even the guideline value for cleanup of industrial land. Concentrations of heavy metals were detected at all sample points, exceeding the Lowest Effect Level (LEL) in 37 out of 48 samples and the Probable Effect Level (PEL) in four of them. High concentrations of nutrients (N and P) were detected, especially outside of the city, where concentrations exceeded even the Severe Effect Level (SEL) for both N and P at one site. DDT concentrations were highest at the beginning of the river, the concentrations becoming lower and lower when getting closer to the river mouth. At three of the six sampling sites, DDT concentrations exceeded the LEL. PCB levels were lower than the LEL. This was attributed to unsuitable handling of the samples before analysis and therefore the PCB concentration levels requires further investiga-tion. The continued monitoring of the sediments is of great need, therefore a proposal for a monitoring program was written. It was estimated that Bîc contributes 118000 tons of suspended particles to Dniester each year, almost 60 % more per km2 than Dniester contributes to the Black Sea.
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Camci, Gulden. "Application Of Isokinetic Sampling Technique For Local Solid Densities In Upward Liquid-solid Flows Through An Annulus." Master's thesis, METU, 2003. http://etd.lib.metu.edu.tr/upload/1089796/index.pdf.
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In this study, radial solid density distributions in upward flowing water-feldspar mixtures through a concentric annulus were investigated. Local solid density measurements were performed at a test cross-section in the fully developed flow region of a concentric annulus, which is a part of a closed-loop system consisting of a head tank, a variable speed slurry pump, an orificemeter, a heat exchanger, an annulus, a temperature probe, and a drain line. The solid particles with mean diameters of 72 and 138 &<br>#61549<br>m at two different feed solid concentrations of 1 and 2 % v/v were used in the prepared slurries. The dependent variables being local solid density, local mixture velocity, and axial frictional pressure drop along the test-section, an experimental work was performed to obtain the radial solid density profiles and axial pressure gradients at different operating conditions.
To determine the local solid densities, a sampling probe was used. At the beginning, this probe was used as a pitot tube to measure the local velocities in the test cross-section. Making use of these data, local solid densities were measured with the same probe under isokinetic and nonisokinetic conditions to compare both.
For this purpose, an isokinetic sampling unit was designed and constructed to withdraw the samples under isokinetic flow conditions, at which the sampling velocity in the probe equated to the true flow velocity in the annulus very closely. The required constant back-pressure was supplied by pressurized N2 gas to equate these velocities to each other. The amounts of solids in the slurry samples collected at seven different radial locations in the test area under isokinetic and non-isokinetic conditions were determined by the gravimetric method.
Local solid densities showed more uniform trends at the feed solid concentration of 1% v/v than those at 2% v/v. Increasing the feed solid concentration and particle size changed the shape of these profiles. The obtained local solid densities were generally higher near the outer wall than those near the inner wall<br>this result was consistent with the literature. As a general trend, local solid densities showed a decreasing trend at around a dimensionless radial distance of &<br>#61548<br>=0.4, where the slurry velocity profile had its maximum value. It was observed that the two-phase axial frictional pressure gradients along the test section in the fully developed flow region increased with increasing feed solid concentration and the particle size at a constant slurry flow rate.
Isokinetic sampling results showed that the local solid densities increased consistently with the increasing slurry velocity at all radial distances in the annular gap, while this trend was not observed clearly in the non-isokinetic measurements. Also the variations of the local solid densities along the radial distance were more obvious in the isokinetic results while these variations were obscured under nonisokinetic conditions by the experimental error at a higher level.
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Rosdahl, Hans. "Microdialysis sampling from skeletal muscle and adipose tissue with special reference to the effects of insulin on tissue blood flow and glucose metabolism /." Stockholm, 1998. http://diss.kib.ki.se/1998/91-628-3050-3.
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Bauer, Ulrike. "Evaluation of Silicone-Based Passive Samplers for Monitoring Organic Aquatic Pollutants." Thesis, Griffith University, 2008. http://hdl.handle.net/10072/367524.
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Pollution of waterways with anthropogenic organic chemicals can pose a risk to the environment and human health. Monitoring the concentrations of such chemicals is indispensable in the assessment of potential risks and in the evaluation of sources and fates, which is crucial to risk management. Monitoring of anthropogenic organic pollutants remains a challenge to regulators. For example, environmentally relevant concentrations of many nonpolar organic anthropogenic chemicals are often in the lower nanogram range. Hence, a substantial concentration of the analytes of interest is required in order to detect these at ultratrace concentrations. Sampling, transport and extraction of large volumes of water pose substantial challenges and are very expensive. Furthermore, snap shot samples may be not representative and can miss point in time or sporadic events. High volume active sampling systems on the other hand can require a great amount of maintenance and are limited by financial as well as logistic issues, such as access to energy to power the system. Passive sampling however, has the potential to exceed active and grab sampling methods, as the sampling devices can be deployed over extended periods of time, they do not require maintenance or electricity and they are relatively cheap.
In this study, silicon rubber (SR) was evaluated as a tool for the monitoring of anthropogenic organic chemicals in water. SR passive samplers were calibrated for a broad range of chemicals (i.e. organic pesticides and PAHs), ranging in log from 2.61–6.90. Samplers were calibrated in different environmental flow scenarios, confirming that flow is an important factor in affecting the exchange kinetics of chemicals. The results demonstrated that water side resistance is the rate limiting resistance for the uptake of chemicals into SR passive samplers under most ambient conditions. In addition to the sampling rate––where possible––silicon rubber to water partition coefficients were determined for some more polar chemicals, which approached equilibrium with the sampler during the experiments.
After these initial laboratory experiments, SR passive samplers were deployed at different sites in South East Queensland to evaluate the performance of the SR material and to identify advantages and limitations of the methods. In the first field study, SR passive samplers were used for longterm monitoring of pesticides after a point source contamination. This study showed the good reproducibility and excellent sensitivity of the SR passive samplers.
In a second field study, the efficiency of the SR passive samplers to predict pesticide occurrence in water was compared with the traditional way of determining pesticide occurrence by collecting and analysing fish from the study sites. The latter still remains a valid method for the detection of deregistered organochlorine pesticides. Nevertheless, the SR passive samplers showed properties that allowed partitioning of polar compounds into the samplers as well as the accumulation of more hydrophobic chemicals, and together with the fish sampling proved to be a sensitive monitoring tool to determine pesticide concentrations in water.
The application of performance reference compounds (PRCs) on SR passive samplers was evaluated and compared to the use of passive flow monitors (PFMs). The PRC approach was shown to have certain drawbacks, mainly due to variations in the amount of PRC loaded on to the samplers as well as the limited availability of sufficient compounds that are suitable as PRCs. In this study, PFMs proved to be a valid replacement of the PRC technique for obtaining information about the flow conditions during sampler deployment. The loss of gypsum from the PFM was used to construct a preliminary model to predict the volume of water cleared by the SR passive samplers during the exposure. The model could then be successfully validated by using three deployments at different sites and under varying environmental conditions during the exposure.
Furthermore, a method was developed to extract SR passive samplers in order to assess genotoxicity of the samples in the umuC bioassay. A suitable method was established to eliminate blank toxicity. The application of a positive control showed promising results, however SR samplers deployed in a preliminary field study and subjected to the umuC assay did not yield positive results, as they were substantially below the detection limit of the assay.
This project has shown that silicone rubber is a promising passive sampling material. It can be used for the detection of a wide range of organic chemicals with octanol–water partition coefficients ranging from less than 1,000 until up to 10,000,000. Once calibrated, the SR passive samplers could be used to predict concentrations of these chemicals in water and can now be used as a valid tool for environmental monitoring.<br>Thesis (PhD Doctorate)<br>Doctor of Philosophy (PhD)<br>Griffith School of Environment<br>Faculty of Science, Environment, Engineering and Technology<br>Full Text
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Xie, Xiaofeng. "High Flow Air Sampler for Rapid Analysis of Volatile and Semi-Volatile Organic Compounds." BYU ScholarsArchive, 2015. https://scholarsarchive.byu.edu/etd/6165.
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Volatile and semi-volatile organic compounds are ubiquitous, and some of them are hazardous. The ability to rapidly detect and identify trace levels of them in air has become increasingly important. The conventional device used today for sampling and concentrating them in air is thermal desorption tubes filled with specific sorbents, which can only collect air samples at flow rates of 100-200 mL/min. In order to detect low concentration (ppt level) VOC compounds, long sampling time (>2 h) and sensitive detection are required. At the same time, portable instrumentation for on-site analysis has been developing rapidly. The somewhat lower performance of portable instruments compared to benchtop systems requires the sampling of even greater sample volume in order to reach the same detection limits. In this study, two high flow rate air sampling devices, i.e., a multi-capillary trap and a concentric packed trap, were developed to sample a large volume of air in a short time period. The multi-capillary trap was constructed by bundling analytical capillary gas chromatography columns together in parallel. As low as single digit ppt detection limits were reached in less than 25 min with this trap, and as high as 8.0 L/min flow rate was sampled. The simple and compact multi-capillary trap could be easily used with a conventional thermal desorption system to perform high flow rate sampling. A concentric packed high flow rate trap was also developed by packing sorbent layers concentrically around an empty tube. The concentric packed trap achieved a high flow rate (>10 L/min) because it had a high surface area and short sorbent bed. Also, its large sorbent amount (>1 g) provided large breakthrough volume (>100 L) required to achieve low detection limits. An equilibrium distribution sampling system was developed by absorbing selected analytes in granular PDMS to provide calibration for on-site instrumentation. Furthermore, a needle trap device was coupled in tandem to both high flow rate air samplers to perform second-stage concentration of VOCs down to the ppt level. Concentration factors of 104 to 105 were achieved within 30 min using both systems, i.e., over 10 to 100 times more sample was collected compared to conventional TD systems.
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Dikgale, Neo. "Analysis of barometric pressure temperature and air density on flow rate of gravimetric dust sampling pumps and silica dust monitoring at a South African gold mine." Diss., University of Pretoria, 2017. http://hdl.handle.net/2263/65868.
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The eagerness to overcome workforce health crises in the mining industry continues to be a challenge, undermining health system transformation globally and more specifically in South Africa. Despite policy implementation and interventions towards health system improvements in South Africa’s mining sector, literature does not provide a detailed narrative on accurate analysis and calibration, when barometric pressure, temperature and air density variations occur, during crystalline silica dustmonitoring processes. Incorrect reporting of crystalline silica concentrations may therefore be a contributing factor in unceasing new cases of silicosis and other silica dust related health issues. This study aimed to determine the impact of barometric pressure, air density and temperature on the concentration of respirable dust samples, using personal gravimetric dust sampling instrument. The study further sought to establish the impact these environmental variables may contribute and whether this can be quantified and applied on measurements taken to correct historical measurement results. The following objectives were used to: • Determine the impact of barometric pressure, air density and temperature on the flow rate of various gravimetric dust sampling pumps. • Determine the impact of barometric pressure, air density and temperature on the concentration of respirable dust samples, using dust sampling instruments. • Establish the impact of the environmental variables that may contribute to the differences in the results obtained. • Establish whether the GilAir Plus and Tuff pumps do maintain a constant flow rate at various barometric pressure levels. • Analyse gravimetric data to determine the percentage error, if correction factor needs to be applied. • Analyse the particulate matter collected on the filter media to determine the type and particle sizes of the particulate. When a personal airborne silica dust sampler is used underground, it is subjected to extreme ambient thermal conditions, such as barometric pressure, air density changes, and temperature variations due to changes in the geothermal gradient and the increase in virgin rock temperature. However, these changes are not accounted for, neither are they considered when sampling strategies are employed. The current industry sampling methodologies are applied in a manner that assumes that the airborne particulate sampling device, set at certain flow rate under certain conditions of barometric pressure, air temperature and density on surface, will maintain that flow rate when subjected to different ambient environmental conditions underground. The study found that barometric pressure, air density and temperature changes do affect the GilAir Plus and Tuff gravimetric dust pump’s flow rate and therefore underground conditions need to be considered when gravimetric sampling is conducted. The ability of an individual pump to adjust its flow rate as it encounters variations in barometric pressure, temperature and density is dependent on its age, amongst other factors. The GilAir-3 pumps were the only pumps that indicated an increase in flow rate as barometric pressure increased, unlike the GilAir Plus and Tuff pumps. The implications hereof are that the GilAir Plus and Tuff pumps overcompensate for the changes in environmental conditions. The Tuff and GilAir plus, although at first glance seem to be exaggerating the exposure levels, should they be used as instruments of choice for monitoring dust exposures in industry, it could mean that the results obtained, may demand stricter dust control measures be implemented. Instruments of high accuracy in determining worker exposure to quartz are required. This remains that the primary reason for conducting measurements is not merely for compliance, but rather to improve dust control strategies.<br>Dissertation (MSc)--University of Pretoria, 2017.<br>School of Health Systems and Public Health (SHSPH)<br>MSc<br>Unrestricted
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Anderson, Malin. "Dynamics of phosphorus transport and retention in a wetland receiving drainage water from agricultural clay soils." Thesis, Linköpings universitet, Ekologi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-68773.
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A constructed wetland (0.08 ha) receiving drainage water from a small agricultural catchment (22 ha) with clay soil, was investigated with respect to phosphorus dynamics and retention. The aim was to evaluate the function of the wetland with respect to phosphorus retention, and relate that to gross sedimentation as measured with sediment traps. Hydraulic load and phosphorus retention were estimated for 2003-2010 based on monitoring data. Furthermore, water quality dynamics was studied during three intensive sampling periods of 3-5 days during 2010. For each period, phosphorus retention was calculated and the relationship between flow and phosphorus concentrations analysed. Additionally, the gross sedimentation rate was estimated using sediment traps, and the phosphorus, carbon and nitrogen content analysed. The results suggested that there was no net retention of phosphorus during 2003-2010, except for 04/05. During the intensive sampling periods, release of phosphorus from the wetland mainly occurred during high flow. Sediment analyses showed that settling of inflow particles mostly occurred in the inlet pond, while the sediment found in a shallow vegetated area and outlet pond likely originated from internal processes rather than from the catchment. In fact, the gross sedimentation of phosphorus during April-July and July-August, respectively, exceeded the measured phosphorus inflow. The results showed that short periods with rapid flow increases were crucial for the wetlands function and thus high frequency sampling must be done during these periods. Furthermore, it seems that the particles lost from the catchment during high flows are too small to settle in the wetland.
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Hamon, Camille. "Probabilistic security management for power system operations with large amounts of wind power." Doctoral thesis, KTH, Elektriska energisystem, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-166398.
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Power systems are critical infrastructures for the society. They are therefore planned and operated to provide a reliable eletricity delivery. The set of tools and methods to do so are gathered under security management and are designed to ensure that all operating constraints are fulfilled at all times. During the past decade, raising awareness about issues such as climate change, depletion of fossil fuels and energy security has triggered large investments in wind power. The limited predictability of wind power, in the form of forecast errors, pose a number of challenges for integrating wind power in power systems. This limited predictability increases the uncertainty already existing in power systems in the form of random occurrences of contingencies and load forecast errors. It is widely acknowledged that this added uncertainty due to wind power and other variable renewable energy sources will require new tools for security management as the penetration levels of these energy sources become significant. In this thesis, a set of tools for security management under uncertainty is developed. The key novelty in the proposed tools is that they build upon probabilistic descriptions, in terms of distribution functions, of the uncertainty. By considering the distribution functions of the uncertainty, the proposed tools can consider all possible future operating conditions captured in the probabilistic forecasts, as well as the likeliness of these operating conditions. By contrast, today's tools are based on the deterministic N-1 criterion that only considers one future operating condition and disregards its likelihood. Given a list of contingencies selected by the system operator and probabilitistic forecasts for the load and wind power, an operating risk is defined in this thesis as the sum of the probabilities of the pre- and post-contingency violations of the operating constraints, weighted by the probability of occurrence of the contingencies. For security assessment, this thesis proposes efficient Monte-Carlo methods to estimate the operating risk. Importance sampling is used to substantially reduce the computational time. In addition, sample-free analytical approximations are developed to quickly estimate the operating risk. For security enhancement, the analytical approximations are further embedded in an optimization problem that aims at obtaining the cheapest generation re-dispatch that ensures that the operating risk remains below a certain threshold. The proposed tools build upon approximations, developed in this thesis, of the stable feasible domain where all operating constraints are fulfilled.<br><p>QC 20150508</p>
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Persinger, Jason William. "Developing Habitat Suitability Criteria for Individual Species and Habitat Guilds in the Shenandoah River Basin." Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/31646.
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The diversity of fish species found in warmwater stream systems provides a perplexing challenge when selecting species for Instream Flow Incremental Methodology (IFIM) studies. An often-suggested approach has been to use habitat guilds to incorporate the diversity found in these systems. My goal is to determine the feasibility of developing habitat suitability criteria (HSC) for the entire fish assemblage in the North and South Fork Shenandoah River, Virginia, using habitat guilds.
I examined the strengths and weaknesses of direct underwater observation via snorkeling and throwable anode electrofishing to sample fish habitat use (e.g., depth, velocity, distance to cover, dominant and subdominant substrate, cover, and embeddedness) indicates that using the data collected from both techniques may produce better criteria than using just one of the two sampling techniques.
To develop habitat suitability criteria using habitat guilds I placed each species a priori into a guild based on a hypothesized guild structure. Transitional life stages with significantly different habitat use were placed separately into the guild structure. The four guilds (riffle, fast generalist, pool-run, and pool-cover) were found to be significantly different from each other using the data collected for the species assigned to the guilds. Criteria were then developed for representative species from each guild and the entire guilds.
Criteria developed for depth, velocity, Froude number, cover, distance to cover, substrate, and embeddedness were used to estimate a habitat response function (i.e., the relations between usable habitat and stream flow) for a representative species from each guild, the guild itself, and for a second species from each guild for comparisons. Both the representative species and guild criteria showed similar habitat response functions for the riffle guild, fast generalist guild, and pool-run guild. However, neither set of criteria performed well for the pool-cover guild. For guilds, other than pool-cover, either the guild or the representative species approach may be a viable option to developing habitat suitability criteria.
The transferability tests were performed to determine if criteria developed in the North Fork Shenandoah River, Virginia would transfer to the South Fork Shenandoah River, Virginia. Only criteria for the margined madtom (Noturus insignis) and the juvenile smallmouth bass (Micropterus dolomieu) transferred for both suitable and optimal habitat. Criteria for mottled sculpin (Cottus bairdi), Cyprinella sp. (spotfin and satinfin shiners), river chub (Nocomis micropogon), adult and juvenile redbreast sunfish (Lepomis auritus), and adult smallmouth bass did not transfer. Only the pool-cover guild criteria transferred for both suitable and optimal habitat, while riffle guild, fast generalist guild, and pool-run guild criteria did not transfer. I recommend the use of site-specific criteria for the South Fork Shenandoah or different variable combinations.<br>Master of Science
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Menuchi, Marcos Rodrigo Trindade Pinheiro [UNESP]. "Locomoção visualmente guiada na transposição de obstáculos: efeitos de amostras visuais estáticas e dinâmica." Universidade Estadual Paulista (UNESP), 2005. http://hdl.handle.net/11449/87418.
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menuchi_mrtp_me_rcla.pdf: 321486 bytes, checksum: eb28a1ece2b065e6d1f1861d4c4f8762 (MD5)<br>Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)<br>Durante a locomoção, ocorre um padrão de movimento visual referido como um campo de fluxo óptico. Para explorar como os ajustamentos locomotores são influenciados por este padrão, um paradigma experimental foi desenvolvido para anular o fluxo óptico durante a locomoção e ultrapassagem de obstáculo. O objetivo deste estudo foi investigar a contribuição de amostragens visuais estáticas e dinâmica na locomoção e ultrapassagem de obstáculos de diferentes alturas. Dez indivíduos (23,4 l 1,28 anos de idade, de ambos os gêneros) foram convidados a andar sobre uma passarela e ultrapassar um de dois obstáculos personalizados (obstáculo alto = altura do joelho e obstáculo baixo = altura do tornozelo) posicionado a 5m do ponto de partida. Diodos emissores de luz foram afixados no 5º metatarso e face lateral do calcâneo em ambos os pés e suas trajetórias foram filmados por quatro filmadoras digitais posicionadas bilateralmente à passarela. Dois blocos de tentativas foram apresentados em função das condições de amostragens visuais. No primeiro bloco, 10 tentativas com amostragem visual dinâmica (iluminação normal) foram apresentadas. No segundo bloco de tentativas, duas condições de amostragens visuais estáticas foram apresentadas de forma aleatória por meio de uma luz estroboscópica (2 flashes/segundo e 4 flashes/segundo). A duração de cada flash não ultrapassou 16ms e forneceu apenas imagens estáticas do ambiente. A altura do obstáculo foi randomizada em cada bloco de tentativas. Cinco tentativas para cada condição foram coletadas, totalizando 30 tentativas por participante. Todas as imagens foram digitalizadas e reconstruídas no plano tri-dimensional. As variáveis dependentes na fase de aproximação (comprimentos dos dois passos anteriores à ultrapassagem) e na fase de ultrapassagem...<br>During locomotion, a pattern of visual motion referred as an optic flow field occurs. In order to explore how the locomotor adjustments are influenced by this pattern, an experimental paradigm was developed to remove the optic flow during locomotion and obstacle avoidance. The aim of this study was to investigate the contribution of the static and dynamic visual sampling on the locomotion and obstacle avoidance of different heights. Ten individuals (23.4 l 1.28 years of age, both genders) were invited to walk on a pathway and to avoid one out of two personalized obstacles (high obstacle = knee height and low obstacle = ankle height) positioned 5m from the starting position. Light emitting diodes were fixed on the fifth metatarsal and calcaneus lateral face in both feet and their trajectories were recorded by four digital cameras bilaterally positioned related to the pathway. Two trial blocks were presented depending of the visual sampling conditions. In the first block, 10 trials with visual dynamic sampling (normal light) were presented. In the second trial block, two conditions of the static visual sampling frequencies were presented in an randomized way by means of the stroboscopic light (2 flashes/second or 4 flashes/second). Each flash duration was about 16ms and provided only environmental static images. Obstacle height was randomized for each trial block. Five trials for each experimental condition were collected totalizing 30 trials for each participant. All images were digitalized and reconstructed in the 3D plane. Dependent variables in the approach phase (last two step lengths before crossing) and in the crossing phase (horizontal toe distance to the obstacle prior crossing, obstacle toe clearance and mean horizontal velocity for each foot) were selected. The results revealed differences... (Complete abstract, access undermentioned electronic address)
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Clark, Brandi Nicole. "Effect of Installation Practices on Galvanic Corrosion in Service Lines, Low Flow Rate Sampling for Detecting Water-Lead Hazards, and Trace Metals on Drinking Water Pipeline Corrosion: Lessons in Unintended Consequences." Diss., Virginia Tech, 2015. http://hdl.handle.net/10919/73180.
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Corrosion of drinking water distribution systems can cost water utilities and homeowners tens of billions of dollars each year in infrastructure damage, adversely impacting public health and causing water loss through leaks. Often, seemingly innocuous choices made by utilities, plumbers, and consumers can have a dramatic impacts on corrosion and pipeline longevity.
This work demonstrated that brass pipe connectors used in partial lead service line replacements (PLSLR) can significantly influence galvanic corrosion between lead and copper pipes. Galvanic crevice corrosion was implicated in a fourfold increase in lead compared to a traditional direct connection, which was previously assumed to be a worst-case connection method.
In field sampling conducted in two cities, a new sampling method designed to detect particulate lead risks demonstrated that the choice of flow rate has a substantial impact on lead-in-water hazards. On average, lead concentrations detected in water at high flow without stagnation were at least 3X-4X higher than in traditional regulatory samples with stagnation, demonstrating a new 'worst case' lead release scenario due to detachment of lead particulates.
Although galvanized steel was previously considered a minor lead source, it can contain up to 2% lead on the surface, and elevated lead-in-water samples from several cities were traced to galvanized pipe, including the home of a child with elevated blood lead.
Furthermore, if both galvanized and copper pipe are present, as occurs in large buildings, deposition corrosion is possible, leading to both increased lead exposure and pipe failures in as little as two years. Systematic laboratory studies of deposition corrosion identified key factors that increase or decrease its likelihood; soluble copper concentration and flow pattern were identified as controlling factors. Because of the high copper concentrations and continuous flow associated with mixed-metal hot water recirculating systems, these systems were identified as a worst-case scenario for galvanic corrosion.
Deposition corrosion was also confirmed as a contributing mechanism to increased lead release, if copper pipe is placed before a lead pipe as occurs in partial service line replacements. Dump-and-fill tests confirmed copper solubility as a key factor in deposition corrosion impacts, and a detailed analysis of lead pipes from both laboratory studies and field tests was consistent with pure metallic copper deposits on the pipe surface, especially near the galvanic junction with copper.
Finally, preliminary experiments were conducted to determine whether nanoparticles from novel water treatment techniques could have a negative impact on downstream drinking water pipeline infrastructure. Although increases in the corrosion of iron, copper, and stainless steel pipes in the presence of silver and carbon nanomaterials were generally small or non-existent, in one case the presence of silver nanoparticles increased iron release from stainless steel by more than 30X via a localized corrosion mechanism, with pitting rates as high as 1.2 mm/y, implying serious corrosion consequences are possible for stainless steel pipes if nanoparticles are present.<br>Ph. D.
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Prunier, Jérome. "Echantillonnage individu-centré en génétique du paysage : étude de l'impact de la fragmentation d'origine anthropique sur la dispersion du triton alpestre Ichthyosaura alpestris." Thesis, Lyon 1, 2012. http://www.theses.fr/2012LYO10263/document.
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Les activités d'origines anthropiques entraînent des modifications profondes du paysage : dans ce contexte, le succès de dispersion revêt une grande importance pour la persistance à long terme des populations animales et végétales. La génétique du paysage est une discipline récente qui permet de détecter et de modéliser les flux de dispersion de manière indirecte par le biais de l'identification des flux de gènes dans l'espace. Bien qu'il ait été suggéré delongue date qu'un échantillonnage individu-centré pouvait permettre de s'affranchir de certains biais liés à unedélimitation a priorides populations, les études portant sur des organismes présentant une distribution spatiale discontinue restent malgré tout le plus souvent basées sur un échantillonnage réalisé à l'échelle populationnelle. C'est sur cette thématique qu'ont porté mes travaux de thèse. Des résultats obtenus par simulations montrent qu'augmenter le nombre de points échantillonnés dans l'espace au détriment du nombre d'individus par agrégat peut permettre une meilleure détection de l'influence de la matrice sur les flux de gènes, quelque soit le régime de dispersion et le contexte paysager considérés. Appliqué à l'étude de la dispersion du triton alpestre Ichthyosaura alpestris, d'une part en paysage fragmenté par des infrastructure linéaires de transport (isolation par barrières aux flux de gènes IBB) et d'autres part en paysage agricole (isolation par résistance de la matrice paysagère IBR), l'échantillonnage individu-centré apparaît comme une alternative flexible et efficace à l'échantillonnnage populationnel classique<br>Anthropogenic activitites lead to profound landscape alterations : dispersal success thus holds a paramount importance for long-term persistence of populations. Landscape genetics is a recent discipline aiming to detect and describe dispersal patterns through indirect estimations of gene flow. Although the use of an individual-based sampling scheme has been proposed for a ;ong time to get round the issue of an a priori delimitation of population boundaries, most landscape gentic studies are still based on a population-based sampling scheme. results from simulations showed that decreasing the sampling coverage on individuals within populations in favour of a better sampling coverage of aggregates through space allowed a better detection of the impacts of landscape on gene flow, whatever the individual dispersal behaviour or the landscape configuration. when considering the dispersal patterns in the alpine newt Ichthyosaura alpestris, both in the vicinity of large transport infrastructures (Isolation-by-barrier IBB) and in agricultural landscape (Isolation-by-landscape-resistance IBR), the individual-based sampling scheme proved to be a flexible and efficient methodological alternative to the more conventional population-based sampling scheme
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Němec, Miroslav. "Časové vzorkování obrazového toku." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2009. http://www.nusl.cz/ntk/nusl-217966.
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The aim of this Master’s thesis is to develop a theoretical introduction to the issue of the image flow time sampling, taking into account the various factors that affect sampling. Furthermore, there is proposed idea diagram of the model, which will simulate the events described, and created the model in the programming environment Matlab. Finally, there are defined the labs that will support teaching dealing with the imaging systems.
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Delport, Jacques. "Critical Substation Risk Assessment and Mitigation." Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/83444.
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Substations are joints in the power system that represent nodes that are vital to stable and reliable operation of the power system. They contrast the rest of the power system in that they are a dense combination of critical components causing all of them to be simultaneously vulnerable to one isolated incident: weather, attack, or other common failure modes. Undoubtedly, the loss of these vital links will have a severe impact to the to the power grid to varying degrees.
This work creates a cascading model based on protection system misoperations to estimate system risk from loss-of-substation events in order to assess each substation's criticality. A continuation power flow method is utilized for estimating voltage collapse during cascades. Transient stability is included through the use of a supervised machine learning algorithm called random forests. These forests allow for fast, robust and accurate prediction of transient stability during loss-of-substation initiated cascades.
Substation risk indices are incorporated into a preventative optimal power flow (OPF) to reduce the risk of critical substations. This risk-based dispatch represents an easily scalable, robust algorithm for reducing risk associated with substation losses. This new dispatch allows operators to operate at a higher cost operating point for short periods in which substations may likely be lost, such as large weather events, likely attacks, etc. and significantly reduce system risk associated with those losses.
System risk is then studied considering the interaction of a power grid utility trying to protect their critical substations under a constrained budget and a potential attacker with insider information on critical substations. This is studied under a zero-sum game theoretic framework in which the utility is trying to confuse the attacker. A model is then developed to analyze how a utility may create a robust strategy of protection that cannot be heavily exploited while taking advantage of any mistakes potential attackers may make.<br>Ph. D.
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Opravil, Jan. "Systém pro optické měření." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2012. http://www.nusl.cz/ntk/nusl-219684.
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This diploma thesis deals with the creation and testing of optical measurement system. There are basic parts of computer vision. Some ways of image preprocessing and templates matching are discussed. Everything is directed to a particular practical task. Selected methods for templates matching are the Correlation Method, the Classical and Hybrid Hausdorff Distance, Radial and Circular Sampling Space. These methods are programmed in C++ and they are compared with function for searching templates from specific library.
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Karlsson, Johan, and Hannes Öckerman. "Föroreningar från gata till å : Utvärdering av beräkningsmetod för föroreningsbelastningfrån dagvatten genom en fallstudie i Uppsala." Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-277033.
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Vi lever i ett samhälle med pågående urbanisering. Nyexploateringar och förtätningar istadsmiljöer bidrar till minskad infiltration och evapotranspiration samt ökad ytavrinning avregn- och smältvatten; så kallat dagvatten. Det är viktigt att kvantifiera denna diffusaföroreningskälla i urbana miljöer då bland annat näringsämnen och tungmetaller transporterasmed dagvattnet, vilket bidrar till försämrad status i recipienter. Enföroreningsbelastningsmodell för näringsämnen i dagvatten på nationell nivå används avSvenska miljöemissionsdata (SMED). Beräkningsmetoden använder empiriskt framtagnaavrinningskoefficienter och belastningsschabloner som varierar beroende påmarkanvändningsslag. Flödesproportionell provtagning av totalhalter kväve, fosfor, bly, koppar, zink, kadmium ochsuspenderad substans genomfördes under nio veckor i ett av Uppsalas störstadagvattenavrinningsområden. Syftet var att kvantifiera områdets föroreningsbelastning för attutvärdera och föreslå förbättringar till SMED:s beräkningsmetod som enligt tidigare studierhar stora osäkerheter, men även för att ge underlag till placering av eventuella reningsåtgärderi området. Provtagningen kompletterades med en modellutvärdering där beräkningsmetodenskänslighet med avseende på markanvändning och inkludering av basflöde testades. Även enmer fysikaliskt förankrad modell för näringsämnestransport i naturliga avrinningsområdenanvändes i modellutvärderingen. Resultaten visade att bly, koppar och zink transporteras till Fyrisån i koncentrationer somöverskrider föreslagna regionala riktvärden för dagvatten. För koppar och zink är även dentotala belastningen på recipient högre än tidigare modellerade värden. Då tungmetaller, menäven fosfor, till stor del transporteras i partikulär form bör en eventuell reningsåtgärd iavrinningsområdet fokusera på att avskilja partikulärt material. Åtgärden bör även placerasuppströms industrin GE Healthcare Bio-Sciences AB där föroreningskoncentrationerna spädsut genom att stora volymer kyl- och regenereringsvatten tillförs dagvattennätet. Vidare visade modellutvärderingen att när SMED:s beräkningsmetod applicerades på detstuderade avrinningsområdet överskattades volymavrinningen från dagvattnet jämfört medprovtagningsresultaten medan medelkoncentrationen för kväve underskattades. För fosfor gavprovtagningsresultaten och beräkningsmetoden samstämmiga svar. Sammantagetöverskattade modellen fosforbelastningen något men underskattade kvävebelastningen. Förkväve har basflödet visat sig stå för en betydande del av belastningen och bör därför iframtiden inkluderas i SMED:s beräkningsmetod. Även den markanvändningskarta somanvänds i metoden bör bytas ut på grund av dess inaktualitet samt att modellutvärderingenvisade relativt stora känsligheter i resultaten för ändring i markanvändning.<br>We live in a society with an ongoing urbanization. New development projects anddensifications in urban areas contribute to reduced infiltration and evapotranspiration and anincreased surface runoff from rain and melt water, i.e. stormwater. It is essential to quantifythis diffuse source of pollution in urban environments since nutrients, heavy metals and otherpollutants, are transported by the stormwater and contribute to recipient degradation. Anutrient pollution load model in stormwater is used by Swedish environmental emission data(SMED) on a national level. The SMED computational method utilizes empirical runoffcoefficients and standard concentrations, which vary depending on the catchment land-use. Flow proportional sampling of total concentrations of nitrogen, phosphorus, lead, copper,zinc, cadmium and suspended solids was conducted during nine weeks in one of the largeststormwater catchments in Uppsala city, Sweden. The study aimed at quantifying the pollutionload of the catchment in order to evaluate and suggest improvements to the SMEDcomputational method, which contains large uncertainties according to previous studies.Furthermore, the study aimed at providing a basis for potential treatment measures in thecatchment. The sampling was complemented with a model evaluation where the sensitivity ofthe computational method was tested with respect to land-use input and the inclusion ofbaseflow. The model evaluation also included a comparison with a more physically basedmodel for nutrient transport in natural catchments. The results revealed that lead, copper and zinc are discharged into the Fyris River inconcentrations exceeding proposed regional guideline values. For copper and zinc the totalpollution loads on the recipient are higher than previously modeled values. As heavy metalsand phosphorus are transported largely in particulate form the potential treatment measureshould have the ability to effectively separate particulate matter from the stormwater matrix.Due to emissions of large volumes of cooling and regeneration water from the industry GEHealthcare Bio-Sciences AB, the stormwater pollutants are diluted. The treatment measureshould therefore be placed upstream from the industry. When applying the SMED computational method on the studied catchment, the modeloverestimated the runoff volume from stormwater compared to the sampling results, while theaverage nitrogen concentration was underestimated. Regarding phosphorus concentrations,the model and the sampling results concurred relatively well. This resulted in a higherphosphorus, but lower nitrogen, pollution load predicted by the model. It can partly beattributed the fact that baseflow transport of nitrogen is a significant part of the total pollutionload, and should thus be included in the SMED computational method in future calculations.Another model improvement would be to replace the outdated land-use map currently beingused in the method as the model evaluation indicated a relatively large sensitivity in theresults with regards to alterations in the land-use type input.
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Lancereau, Quentin. "Modélisation d'un collecteur électrostatique compact en régime laminaire pour la capture de bio-particules submicroniques aéroportées." Thesis, Grenoble, 2012. http://www.theses.fr/2012GRENI111/document.
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La détection d'agents biologiques dans l'air ambiant est devenue un enjeu majeur notamment en environnement hospitalier et dans la protection contre le bioterrorisme. Dans ce contexte, la miniaturisation des dispositifs d'analyse permet d'envisager leur utilisation directement sur la zone d'étude. Afin d'obtenir un échantillon concentré et représentatif, la filtration de l'air reste cependant un point délicat. Parmi les différents principes exploitables pour la collecte de particules aéroportées, l'emploi des forces électriques semble être prometteur pour améliorer les performances des dispositifs qui se trouvent généralement fondés sur des forces inertielles. Dans cette étude, une modélisation fine des collecteurs électrostatiques a été conduite pour une géométrie fil / cylindre. Elle décrit tout d'abord les champs hydrodynamiques d'un écoulement charriant des inclusions dans lequel est imposée une décharge couronne. Une injection éventuelle de vapeur dans la chambre de collecte a nécessité ensuite la détermination des champs de température et concentration de la vapeur. Une analyse dimensionnelle inspectionnelle a montré que ces champs possèdent deux termes de couplage fort dont on a justifié l'omission dans cette étude ; les phénomènes physiques mis en jeu ont alors pu être classés selon une cascade d'influences non réciproques et la résolution numérique du modèle s'en est trouvée facilitée. Quatre configurations d'écoulement différentes, caractérisées par des recirculations d'origine électro hydrodynamiques, ont été identifiées et leurs impacts sur les rendements de collecte quantifiés. De plus, une procédure de dimensionnement des filtres électrostatiques fondée sur un nombre de Deutsch représentatif des rendements a été mise en place. Son exploitation a montré l'intérêt de la mise en parallèle de petits collecteurs pour filtrer des débits d'air importants. Cette étude s'est achevée par l'analyse des effets engendrés par l'injection de vapeur dans la chambre de collecte. Elle a jeté les bases d'une explication pour l'augmentation des rendements de collecte résultant de cette injection<br>Detection of airborne biological agents has become a major challenge especially in hospitals and the protection against bioterrorism. In this context, the miniaturization of analytical devices allows to consider their direct use in the field. To obtain a representative and concentrated sample, air filtration remains a delicate point. Among the various principles used to collect airborne particles, the use of electrical forces seems to be promising to improve performance beyond these of devices that are based on inertial forces.In this study, a detailed model of electrostatic collectors was developed in the wire/cylinder geometry. It first describes the hydrodynamic flow fields carring inclusions in which a corona discharge is imposed. Afterwards, the possible injection of steam into the collection chamber required the determination of the temperature and vapor concentration fields. An inspectionnal dimensional analysis justified the omission of two strong coupling terms. Therefore, in this study, the involved physical phenomena could be classified according to a non-reciprocal influences cascade and the numerical model is become simpler. Four different flow patterns, characterized by their electrohydrodynamic secondary flows, were identified and their impact on the collection efficiencies was quantified. In addition a design procedure of electrostatic filters, based on a representative efficiency Deutsch number, has been developed. This procedure shows the interest of parallelizing small collectors to filter important airflows. This study was completed by the analysis of the effects of steam into the collection chamber. It provides the basis for an explanation of the collection efficiencies increase related to this injection