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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Boundary Control For Automated Sweeping of Finite Element Meshes

Kerr, Robert A. 01 December 1999 (has links) (PDF)
Finite element analysis depends greatly upon a high-quality mesh to be able to provide reasonably accurate answers to engineering problems. Models that need to be analyzed using finite element analysis are becoming increasingly more complex, and correspondingly harder to mesh with good quality. Skew is one quality metric which can cause problems with finite element analyses. This thesis explains how skew is calculated, discusses two common sources of skew: multiply-linked surfaces with interval constraints, and biased edge meshes. Two methods of lessening skew in surface meshes are then presented: the skew control algorithm, and the curve morphing algorithm. These algorithms are discussed in detail, with representative graphics. Examples which demonstrate the skew which arises from the above-mentioned sources are presented. These models are then subjected to the algorithms discussed in the thesis, and a comparison of the skew measure for each example is presented. Finally, areas of possible future work are presented and the possible detrimental effects that the skew control algorithm can exert on the quality metrics of aspect ration and mesh size gradation are discussed.
22

Mapping Of Pressure Losses Through Microchannels With Sweeping-bends Of Various Angle And Radii

Hansel, Chase 01 January 2008 (has links)
MEMS (Micro Electro Mechanical Systems) have received a great deal of attention in both the research and industrial sectors in recent decades. The broad MEMS category, microfluidics, the study of fluid flow through channels measured on the micrometer scale, plays an important role in devices such as compact heat exchangers, chemical and biological sensors, and lab-on-a-chip devices. Most of the research has been focused on how entire systems operate, both experimentally and through simulation. This paper strives, systematically, to map them through experimentation of the previous to untested realm of pressure loss through laminar square-profile sweeping-bend microchannels. Channels were fabricated in silicone and designed so a transducer could detect static pressure across a very specific length of channel with a desired bend. A wide variety of Reynolds numbers, bend radii, and bend angles were repeatedly tested over long periods in order to acquire a complete picture of pressure loss with in the domain of experimentation. Nearly all situations tested were adequately captured with the exception of some very low loss points that were too small to detect accurately. The bends were found to match laminar straight-duct theory at Reynolds numbers below 30. As Reynolds numbers increased, however, minor losses began to build and the total pressure loss across the bend rose above straight-duct predictions. A new loss coefficient equation was produced that properly predicted pressure losses for sweeping-bends at higher Reynolds numbers; while lower flow ranges are left to laminar flow loss for prediction.
23

Potential and Quantification of Street Sweeping Pollutant Reductions towards addressing TMDL WLAs for MS4 Compliance

Hixon, Lee Franklin 07 June 2019 (has links)
Municipal separate storm sewer system (MS4) permittees face costly obligations to reduce pollutant loadings needed to achieve waste load allocations (WLAs) and meet total maximum daily loads (TMDLs). Street sweeping is potentially an effective BMP since streets exist throughout urban watersheds, often are directly connected to the storm sewer, and are found to contain an abundance of contaminants. Although pollutant removal from street sweeping has been evaluated for decades, an understanding of the impact on water quality in receiving streams is elusive. Due to numerous variables, the large number of samples necessary to measure impact in receiving streams may never be obtained. In response, modeled pollutant removal efficiencies based on frequency of sweeping have been recommended to the Chesapeake Bay Program, but these results are suspect. Alternatively, the amount of swept material has emerged as a method to quantify reductions. A sampling study was conducted to measure pollutants in swept material. The study identified the fraction of material susceptible to transport in runoff based on timing of sweeping in relation to runoff events. Based on observed pollutant concentration associations with particle size, the study results in estimates of pollutant concentrations for the fraction of material susceptible to downstream transport, dependent on duration since the last rainfall and type of surface swept, whether the area is a streets or a parking lot. Pollutant loadings and required reductions to achieve the Chesapeake Bay WLAs for various land use sample areas are computed for an average year. Modeled removal efficiencies and results from the sampling study were employed to assess impacts from street sweeping. Modeled efficiencies predict significantly lower impact than measurements of pollutants susceptible to runoff in swept material. Modeled loadings are inconsistent with measurements of swept materials and the rigorous sweeping frequency required for modeled removal efficiency credit appears to be unnecessary. / Doctor of Philosophy / Many localities, state agencies and other public entities that own storm sewer systems are increasingly required to reduce pollutants discharged from their systems to surface waters as a result of programs stemming from the Clean Water Act. Traditional stormwater management practices, such as retention ponds, appear limited towards providing the total pollutant reductions necessary due to physical constraints, opportunity and cost. Street sweeping is potentially an effective alternative practice since streets exist throughout urban watersheds, often are directly connected to the storm sewer, are found to contain an abundance of contaminants and can be cost effective. Although pollutant removal from street sweeping has been evaluated for decades, an understanding of the pollutants removed from stormwater is elusive. Past studies suggest the large number of samples necessary to measure impact from sweeping in receiving streams may never be obtained. In response, pollutant removal estimates have been made using computer models, but modeled results are suspect since they cannot be calibrated. Alternatively, a measure of swept material has emerged as a method to quantify pollutant reductions. A sampling study was conducted to measure pollutants in swept material. Results identify the fraction of swept material washed from the swept surface dependent on timing of sweeping in relation to the duration since the last rainfall. Based on observed pollutant concentration associations with particle size, the study results in estimates of concentrations for the fraction of material susceptible to downstream transport, dependent on duration since the last rainfall and type of surface swept, whether the area is a streets or a parking lot. Application of the results are compared to modeled removal efficiencies towards achieving regulatory compliance within various land use sample areas. Modeled efficiencies predict significantly lower impact than measurements of pollutants susceptible to runoff in swept material. Rigorous sweeping frequency required for modeled removal efficiency credit appears to be unnecessary.
24

Coverage Path Planning in Large-scale Multi-floor Urban Environments : with Applications to Autonomous Road Sweeping / Körvägsplanering i storskaliga och flervåniga stadsmiljöer medtillämpningar mot autonom robotsopning

Engelsons, Daniel January 2021 (has links)
Autonomous lawn mowers and floor cleaning robots are today easily accessible and areutilizing well-studied Coverage Path Planning algorithms. They operate in single-floorenvironments that are small with simple geometry compared to general urban environments such as city parking garages, highway bridges or city crossings. A next step for autonomous cleaning is road sweeping of these complex urban environments. In this work,a new Coverage Path Planning approach, Sampled BA* & Inward Spiral , handling this taskwas compared with existing well-performing algorithms BA* and Inward Spiral. The proposed approach combines the strengths of existing algorithms and demonstrates state-of-the-art performance on three large-scale 3D environments. It generated paths with lessrotation, while keeping the length of the path on the same level. For a given starting point,the new approach had consistently lower cost (length + rotation) for all environments. Forrandom starting points, randomness in the new approach caused less robustness, givingsignificantly higher cost. To improve the performance of the algorithms and remove biasfrom manual tuning, the parameters were automatically tuned using Bayesian Optimization. This makes the evaluation more robust and the results stronger.
25

Assembly and Testing of the Neutral Particle Spectrometer (NPS) Detector

Tiwari, Pramita 05 June 2023 (has links)
No description available.
26

MICROCHIP CAPILLARY ELECTROPHORESIS: A POWERFUL TOOL FOR BINDING STUDIES AND TRACE PROTEIN ANALYSIS USING APTAMER PROBES

GONG, MAOJUN 02 October 2006 (has links)
No description available.
27

Efficient and Physics-based Facial Blendshapes based on ODE sweeping Surface and Newton's second law

Fang, J., Bian, S., Macey, J., Iglesias, A., Ugail, Hassan, Malyshev, A., Chaudhry, E., You, L., Zhang, J.J. 25 March 2022 (has links)
No / Online games require small data of 3D models for low storage costs, quick transmission over the Internet, and efficient geometric processing to achieve real-time performance, and new techniques of facial blendshapes to create natural facial animation. Current geometric modelling and animation techniques involve big data of geometric models and widely applied facial animation using linear interpolation cannot generate natural facial animation and create special facial animation effects. In this paper, we propose a new approach to integrate the strengths of ODE (ordinary differential equation) sweeping surfaces and Newton's second law-based facial blendshapes to create 3D models and their animation with small data, high efficiency, and ability to create special facial effects.
28

Membrane sweeping at term to promote spontaneous labour and reduce the likelihood of a formal induction of labour for postmaturity: a systematic review and meta-analysis

Avsiyovski, H., Haith-Cooper, Melanie, Scally, Andy J. 04 October 2018 (has links)
Yes / The aim of this study was to evaluate the efficacy and the safety of membrane sweeping in promoting spontaneous labour and reducing a formal induction of labour for postmaturity. Based on articles published between 2005 and 2016, 12 electronic databases were searched. Relative risk (RR) and its 95% confidence interval (CI) were used as pooled statistics. A total of seven studies consisting of 2252 participants were selected for the review and meta-analysis. The results revealed that membrane sweeping is advantageous in promoting spontaneous labour (RR = 1.205, 95% CI: 1.133–1.282, p = <.001), and reducing the formal induction of labour for postmaturity (RR = 0.523, 95% CI: 0.409–0.669, p = <.001). The studies reported several varying outcomes for both maternal and foetal morbidities; meta-analyses were performed where possible on each of these and found there to be no statistically significant differences in outcome between the intervention and control groups.
29

Preconcentration strategies in capillary electrophoresis for the determination of pharmaceutical and personal care products

Maijó Ferré, Irene 17 July 2012 (has links)
L'objectiu principal d'aquestaTesi Doctoral és el desenvolupament de diferents estratègies per disminuir els límits de detecció de l’electroforesicapil•lar per a la determinació de compostos farmacèutics i els productes de cura personal. Aquestes estratègies es basen en les tècniques de preconcentració electroforètiques i cromatogràfiques, i l'ús de l’espectrometria de masses com a sistema de detecció. Com a tècniques de preconcentració electroforètiques s'han estudiat les tècniques de samplestacking i sweeping, i com a tècnica de preconcentració cromatogràficas’ha avaluat l'acoblament en línia entre l'extracció en fase sòlida i l'electroforesicapil•lar (In-line SPE-CE). Entre elsPPCPs, aquesta tesi doctoral es centra específicament en els antiinflamatoris no esteroïdals(AINE), els parabens i els filtres ultraviolats. Un altre dels objectius d'aquestaTesi Doctoral és estudiarl’aplicabilitat de les metodologies desenvolupades per a l'anàlisi de mostres ambientals per determinar PPCP. / The main objective of this Doctoral Thesis is the development of different strategies to decrease the detection limits of capillary electrophoresis for the determination of pharmaceutical and personal care products. These strategies are based on electrophoretic and chromatographic preconcentration techniques, and the use of mass spectrometry as a detection system. The electrophoretic preconcentration techniques studied included sample stacking techniques and sweeping while the chromatographic preconcentration technique evaluated was in-line coupling between solid phase extraction and capillary electrophoresis. With respect to PPCPs, this Doctoral Thesis focuses specifically on non-steroidal anti-inflammatory drugs (NSAIDs), parabens and UV-filters. Another objective of this Doctoral Thesis is to study the suitability of the developed methodologies for the determination of PPCPs in environmental samples.
30

Sweeping Jet Film Cooling

Hossain, Mohammad Arif 21 September 2020 (has links)
No description available.

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