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1
Karanka, Joni. "Learning in binocular time-to-contact perception." Thesis, Cardiff University, 2008. http://orca.cf.ac.uk/54808/.
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Time-to-contact (TTC) is defined as the remaining time for an object to reach the observer. This is an important quantity for timing an action such as hitting or catching a ball. This thesis deals with learning processes in TTC perception when binocular vision is available. Chapter 1 studies the learning of TTC in relative discrimination tasks. We did not find learning in this task, but we found that simple correlates of TTC explained the judgments made by the participants. Chapter 2 studies the learning of TTC in absolute estimation tasks. We found that the variable and constant error of the responses reduced with training. Chapter 3 studied the use of feedback in calibrating the timing of TTC estimates. We found that biased timing produced changes in the constant error, suggesting that TTC calibration is guided by feedback. Chapter 4 studied if the reduction of variable error was due to an increased perceptual sensitivity to TTC. However, we failed to find transfer from the absolute estimation tasks to relative discrimination tasks, suggesting that the learning found in Chapter 2 might not be of perceptual origin. In Chapter 5 we studied a large group of participants in laboratory tasks and a natural hitting task. We found that the performance in relative discrimination and absolute estimation tasks could be used to predict hitting skill. This suggests that the perception of TTC can be linked with interceptive timing. Taken together, these results suggest that perceptual sensitivity to TTC changes slightly -if at all- with training, but changes in perceptuo-motor mapping and calibration of the estimates that increase interceptive performance do take place.
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Nilsson, Robin Lindh. "Contact Sound Synthesis in Real-time Applications." Thesis, Blekinge Tekniska Högskola, Institutionen för kreativa teknologier, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-3938.
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Synthesizing sounds which occur when physically-simulated objects collide in a virtual environment can give more dynamic and realistic sounds compared to pre-recorded sound effects. This real-time computation of sound samples can be computationally intense. In this study we investigate a synthesis algorithm operating in the frequency domain, previously shown to be more efficient than time domain synthesis, and propose a further optimization using multi-threading on the CPU. The multi-threaded synthesis algorithm was designed and implemented as part of a game being developed by Axolot Games. Measurements were done in three stress-testing cases to investigate how multi-threading improved the synthesis performance. Compared to our single-threaded approach, the synthesis speed was improved by 80% when using 8 threads, running on an i7 processor with hyper-threading enabled. We conclude that synthesis of contact sounds is viable for games and similar real-time applications, when using the investigated optimization. 140000 mode shapes were synthesized 30% faster than real-time, and this is arguably much more than a user can distinguish.<br>Syntetisering av ljud som uppstår när fysikobjekt kolliderar i en virtuell miljö kan ge mer dynamiska och realistiska ljudeffekter, men är krävande att beräkna. I det här examensarbetet implementerades ljudsyntes i frekvensdomänen baserat på en tidigare studie, och utvecklades sedan vidare till att utnyttja multipla trådar. Enligt mätningar i tre olika testfall kunde den multitrådade implementationen syntetisera 80% fler ljudvågor än den enkeltrådade, på en i7-processor.<br><p>Author's website: www.robinerd.com</p>
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Long, Xinhua. "Loss of contact and time delay dynamics of milling processes." College Park, Md. : University of Maryland, 2006. http://hdl.handle.net/1903/3421.
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Thesis (Ph.D.) -- University of Maryland, College Park, 2006.<br>Thesis research directed by: Mechanical Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Brendel, Esther Simone [Verfasser]. "Safety Strategies in Time-to-Contact Estimation / Esther Simone Brendel." Mainz : Universitätsbibliothek Mainz, 2019. http://d-nb.info/1175400556/34.
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Haulcy, R'mani(R'mani Symon). "Time-to-contact statistics as a proxy for accident probabilities." Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/122699.
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This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.<br>Thesis: S.M., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2019<br>Cataloged from student-submitted PDF version of thesis.<br>Includes bibliographical references (pages 56-58).<br>Accidents are relatively rare, and this makes it difficult to study the impact of traffic system changes or vehicle control changes on accident rates. One potential solution to this problem is the use of time-to-contact (TTC) statistics as a proxy for accident probabilities. Low TTC can be used as a measure of potential danger. Simulations were performed to explore whether inverse TTC can serve as a good proxy of accident probability. The resulting data was then analyzed to investigate how inverse TTC varies with the mixture of vehicles with bilateral control as opposed to car-following control. Previously, it was found that a relatively high mixture ratio is needed to prevent phantom traffic jams. The results in this paper show that there is a benefit to mixing bilateral control cars into general traffic, even at relatively low mixture ratios. Simulations were also performed to see how acceleration and jerk vary with the mixture of vehicles with bilateral control so that passenger comfort could be quantified. The results show that bilateral control improves passenger comfort.<br>by R'mani Haulcy.<br>S.M.<br>S.M. Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science
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Waizenegger, Wolfgang. "Real-time 3D-based Virtual Eye Contact for Video Communication." Doctoral thesis, Humboldt-Universität zu Berlin, 2019. http://dx.doi.org/10.18452/20159.
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Das Problem des fehlenden Augenkontaktes vermindert den Eindruck einer natürlichen Kommunikationssituation bei Videokonferenzen. Während eine Person auf den Bildschirm blickt, wird sie von Kameras aufgenommen, die sich normalerweise direkt daneben befinden. Mit dem Aufkommen von massiv paralleler Computer Hardware und ganz speziell den sehr leistungsstarken Spielegrafikkarten ist es möglich geworden, viele Eingabeansichten für eine Echtzeit 3D Rekonstruktion zu verarbeiten. Eine größere Anzahl von Eingabeansichten mildert Verdeckungsprobleme ab und führt zu vollständigeren 3D Daten. In dieser Arbeit werden neue Algorithmen vorgeschlagen, welche eine hochqualitative Echtzeit 3D Rekonstruktion, die kontinuierliche Anpassung der photometrischen Kameraparameter und die benutzerunabhängige Schätzung der Augenkontaktkameras ermöglichen. Die Echtzeit 3D Analyse besteht aus zwei komplementären Ansätzen. Einerseits gibt es einen Algorithmus, der auf der Verarbeitung geometrischer Formen basiert und auf der anderen Seite steht eine patchbasierte Technik, die 3D Hypothesen durch das Vergleichen von Bildtexturen evaluiert. Zur Vorbereitung für die Bildsynthese ist es notwendig, Texturen von verschiedenen Ansichten anzugleichen. Hierfür wird die Anwendung eines neuen Algorithmus zur kontinuierlichen photometrischen Justierung der Kameraparameter vorgeschlagen. Die photometrische Anpassung wird iterativ, im Wechsel mit einer 3D Registrierung der entsprechenden Ansichten, ausgeführt. So ist die Qualität der photometrischen Parameter direkt mit jener der Ergebnisse der 3D Analyse verbunden und vice versa. Eine weitere wichtige Voraussetzung für eine korrekte Synthese der Augenkontaktansicht ist die Schätzung einer passenden virtuellen Augenkontaktkamera. Hierfür wird die Augenkontaktkamera kontinuierlich an die Augenposition der Benutzer angeglichen. Auf diese Weise wird eine virtuelle Kommunikationsumgebung geschaffen, die eine natürlichere Kommunikation ermöglicht.<br>A major problem, that decreases the naturalness of conversations via video communication, is missing eye contact. While a person is looking on the display, she or he is recorded from cameras that are usually attached next to the display frame. With the advent of massively parallel computer hardware and in particular very powerful consumer graphics cards, it became possible to simultaneously process multiple input views for real-time 3D reconstruction. Here, a greater amount of input views mitigate occlusion problems and lead to a more complete set of 3D data that is available for view synthesis. In this thesis, novel algorithms are proposed that enable for high quality real-time 3D reconstruction, the on-line alignment of photometric camera parameters, and the automatic and user independent estimation of the eye contact cameras. The real-time 3D analysis consist of two complementary approaches. On the one hand, a shape based algorithm and on the other hand, a patch based technique that evaluates 3D hypotheses via comparison of image textures. Preparative to rendering, texture from multiple views needs to be aligned. For this purpose, a novel algorithm for photometric on-line adjustment of the camera parameters is proposed. The photometric adjustment is carried out iteratively in alternation with a 3D registration of the respective views. In this way, the quality of photometric parameters is directly linked to the 3D analysis results and vice versa. Based on the textured 3D data, the eye contact view is rendered. An important prerequisite for this task is the estimation of a suitable virtual eye contact camera. In this thesis, a novel approach is formulated that enables for an automatic adaptation to arbitrary new users. Therefor, the eye contact camera is dynamically adapted to the current eye positions of the users. In this way, a virtual communication environment is created that allows for a more natural conversation.
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Vincent, Ruddy Serge. "Detailed modelling of catalytic chemistry in short contact time reactors." Thesis, Imperial College London, 2008. http://hdl.handle.net/10044/1/9567.
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The current thesis presents a detailed modelling study of the selective oxidation of ethane over noble metal coated surfaces in short contact time reactors. Computational studies were performed featuring heated gas streams flowing through ceramic-foam catalysts coated with platinum and followed by a long inert section. The detailed chemical kinetic mechanisms, with coupled surface and gas-phase chemical reactions, were explored via extensive reaction path and sensitivity analyses to assess the relative contributions of the homogeneous and heterogeneous chemistries and to establish the key heterogeneous pathways driving the chemical processes. A comprehensively validated detailed chemical mechanism was used for the gas phase. The mechanism initially featured 44 chemical species and 271 reversible reactions and was later extended to 176 reactants with 993 reversible reactions. Heterogeneous models describing the surface chemistry were derived on the basis of classical kinetic collision theory and with energy barriers obtained from Density Functional Theory studies combined with the Unity Bond Index-Quadratic Exponential Potential method. The derived surface mechanisms account for differences in site occupation and surface bonding types and include four reaction classes (direct adsorption, adsorption on an adsorbate, surface reactions with adsorbed reactants and uni-molecular surface reactions including desorption) via 35 adsorbed chemical species and 284 reversible reactions. The complete chemistry was thoroughly evaluated by comparison with multiple sets of existing and new experimental data provided by industrial partners. Key modelling parameters in the process, such as streams velocities, temperature profiles, catalyst loading and pressure were critically examined. The reaction dynamics were validated with C2H6/O2/H2 mixtures with different initial hydrogen contents and with oxygen to carbon weight ratios ranging between 0.25 and 0.9. The major chemical pathways for the production of ethylene through the selective dehydrogenation of ethane, combined with the heterogeneous oxidative were identified.
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Patel, Ketan. "Frequency and time domain contact parameter estimation for space robotic operations." Thesis, McGill University, 2003. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=19579.
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Computer simulations play a significant role in the development and operation of space systems because of the difficulty in performing ground-based hardware testing and onorbit tests are impossible before the launch of these systems. Hence, accurate modeling and simulation of space robotic tasks involving contact is very crucial. This in turn implies that accurate model (contact) parameters, used as inputs to the software to represent the contact operation being simulated, are imperative. In this work, we addressed the contact parameter estimation problem for simple contacting geometries (one-point contact) and complex contacting geometries (multiple-point contact). Several frequency domain identification strategies were applied to one-point contact parameter estimation problem to estimate contact stiffness and damping. The performance of these frequency domain algorithms was evaluated and compared with time domain identification algorithms. The identification algorithm for multiple point contact scenario to estimate contact stiffness, damping and coefficient of friction was also investigated. We determined the cause for poor estimation results obtained with previous implementation of this identification algorithm and were able to improve the performance of the algorithm. Finally, a thorough evaluation of sensitivity of the algorithm to noise in measured data was conducted.
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Kopf, Samantha. "The Effect of Juvenile Justice Contact on Family Support Across Time." Bowling Green State University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1585150858834228.
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Hussain, I. "Multiple model based real time estimation of wheel-rail contact conditions." Thesis, University of Salford, 2012. http://usir.salford.ac.uk/38094/.
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The issue of low adhesion between the wheel and the rail has been a problem for the design and operation of the railway vehicles. The level of adhesion can be influenced by many different factors, such as contamination, climate, and vegetation, and it is extremely difficult to predict with certainty. Changes in the adhesion conditions can be rapid and short-lived, and values can differ from position to position along a route, depending on the type and degree of contamination. All these factors present a significant scientific challenge to effectively design a suitable technique to tackle this problem. This thesis presents the development of a unique, vehicle based technique for the real-time estimation of the contact conditions using multiple models to represent variations in the adhesion level and different contact conditions. The proposed solution exploits the fact that the dynamic behaviour of a railway vehicle is strongly affected by the nonlinearities and the variations in creep characteristics. The purpose of the proposed scheme is to interpret these variations in the dynamic response of the wheelset, developing useful contact condition information. The proposed system involves the use of a number of carefully selected mathematical models (or estimators) of a rail vehicle to mimic train dynamic behaviours in response to different track conditions. Each of the estimators is tuned to match one particular track condition to give the best results at the specific design point. Increased estimation errors are expected if the contact condition is not at or near the chosen operating point. The level of matches/mismatches is reflected in the estimation errors (or residuals) of the models concerned when compared with the real vehicle (through the measurement output of vehicle mounted inertial sensors). The output residuals from all the models are then assessed using an artificial intelligence decision-making approach to determine which of the models provides a best match to the present operating condition and, thus, provide real-time information about track conditions.
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Ibrahim, Mustapha. "Investigation of contact time and impact force of particle-surface impacts." Thesis, Glasgow Caledonian University, 2017. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.726774.
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Walloth, Mirjam [Verfasser]. "Adaptive numerical simulation of contact problems : Resolving local effects at the contact boundary in space and time / Mirjam Walloth." Bonn : Universitäts- und Landesbibliothek Bonn, 2012. http://d-nb.info/1044082747/34.
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Pei, Jiantao, and n/a. "The Accuracy of Time-to-Contact Estimation in the Prediction Motion Paradigm." University of Canberra. Applied Science, 2002. http://erl.canberra.edu.au./public/adt-AUC20050627.143329.
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This thesis is concerned with the accuracy of our estimation of time to make contact
with an approaching object as measured by the “Prediction Motion” (PM) technique.
The PM task has commonly been used to measure the ability to judge time to contact
(TTC). In a PM task, the observer's view of the target is occluded for some period
leading up to the moment of impact. The length of the occlusion period is varied and
the observer signals the moment of impact by pressing a response key. The interval
separating the moment of occlusion and the response is interpreted as the observer's
estimate of TTC made at the moment of occlusion. This technique commonly
produces large variability and systematic underestimation. The possibility that this
reflects genuine perceptual errors has been discounted by most writers, since this
seems inconsistent with the accuracy of interceptive actions in real life. Instead, the
poor performance in the PM task has been attributed to problems with the PM
technique. Several hypotheses have been proposed to explain the poor PM
performance. The motion extrapolation hypothesis asserts that some form of mental
representation of the occluded part of the trajectory is used to time the PM response;
the errors in PM performance are attributed to errors in reconstructing the target
motion. The clocking hypothesis assumes that the TTC is accurately perceived at the
moment of occlusion and that errors arise in delaying the response for the required
period. The fear-of-collision hypothesis proposes that the underestimation seen in
the PM tasks reflects a precautionary tendency to anticipate the estimated moment of
contact. This thesis explores the causes of the errors in PM measurements.
Experiments 1 and 2 assessed the PM performance using a range of motion scenarios
involving various patterns of movement of the target, the observer, or both. The
possible contribution of clocking errors to the PM performance was assessed by a
novel procedure designed to measure errors in the wait-and-respond component of
the PM procedure. In both experiments, this procedure yielded a pattern of
systematic underestimation and high variability similar to that in the TTC estimation
task. Experiment 1 found a small effect of motion scenario on TTC estimation.
However, this was not evident in Experiment 2.
The collision event simulated in Experiment 2 did not involve a solid collision. The
target was simply a rectangular frame marked on a tunnel wall. At the moment of
“contact”, the observers passed “through” the target without collision. However,
there was still systematic underestimation of TTC and there was little difference
between the estimates obtained in Experiments 1 and 2. Overall, the results of
Experiments 1 and 2 were seen as inconsistent with either the motion extrapolation
hypothesis or the fear-of-collision hypothesis. It was concluded that observers
extracted an estimate of the TTC based on optic TTC information at a point prior to
the moment of collision, and used a timing process to count down to the moment of
response. The PM errors were attributed to failure in this timing process. The results
of these experiments were seen as implying an accurate perception of TTC.
It was considered possible that in Experiments 1 and 2 observers based their TTC
judgements on either the retinal size or the expansion rate of the target rather than
TTC. Experiments 3 and 4 therefore investigated estimation of TTC using a range of
simulated target velocities and sizes. TTC estimates were unaffected by the resulting
variation in expansion rate and size, indicating that TTC, rather than retinal size or
image expansion rate per se, was used to time the observers' response.
The accurate TTC estimation found in Experiments 1-4 indicates that the TTC
processing is very robust across a range of stimulus conditions. Experiment 5 further
explored this robustness by requiring estimation of TTC with an approaching target
which rotated in the frontoparallel plane. It was shown that moderate but not fast
rates of target rotation induced an overestimation of TTC. However, observers were
able to discriminate between TTCs for all rates of rotation. This shows that the
extraction of TTC information is sensitive to perturbation of the local motion of the
target border, but it implies that, in spite of these perturbations, the mechanism is
flexible enough to pick up the optic TTC information provided by the looming of the
retinal motion envelop of the rotating stimulus.
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Müller, Georg [Verfasser], and Anton [Akademischer Betreuer] Schiela. "Optimal control of time-discretized contact problems / Georg Müller ; Betreuer: Anton Schiela." Bayreuth : Universität Bayreuth, 2019. http://d-nb.info/1188314068/34.
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Noh, Gunwoo. "An evaluation of time integration schemes in the solution of contact problems." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/65313.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2011.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (p. 65-66).<br>Contact analysis is an important branch of structural mechanics. The finite element method has become a major solution approach because of the high nonlinearities in contact problems. A large number of algorithms have been proposed and extensively used to solve engineering problems, but some issues have not been addressed yet. The first purpose of this research is to evaluate attempts to achieve accurate and practical time integration schemes for contact problems. Towards this aim, this study proposes an analytical form of the solutions using the time integration schemes that can be used in the evaluation of different methods. Then, a simple velocity- and acceleration-update process that is combined with the conventional time integration methods is proposed to suppress (as much as possible) spuriously generated energy during the contact events.<br>by Gunwoo Noh.<br>S.M.
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Blaxter, Tam Tristram. "Speech in space and time : contact, change and diffusion in medieval Norway." Thesis, University of Cambridge, 2017. https://www.repository.cam.ac.uk/handle/1810/269365.
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This project uses corpus linguistics and geostatistics to test the sociolinguistic typological theory put forward by Peter Trudgill on the history of Norwegian. The theory includes several effects of societal factors on language change. Most discussed is the proposal that ‘intensive’ language contact causes simplification of language grammar. In the Norwegian case, the claim is that simplificatory changes which affected all of the Continental North Germanic languages (Danish, Swedish, Norwegian) but not the Insular North Germanic Languages were the result of contact with Middle Low German through the Hanseatic League. This suggests that those simplificatory changes arose in the centres of contact with the Hanseatic League: cities with Hansa trading posts and kontors. The size of the dataset required would have made it impossible for previous scholars to test this prediction, but digital approaches render the problem tractable. I have designed a 3.5m word corpus containing nearly all extant Middle Norwegian, and developed statistical methods for examining the spread of language phenomena in time and space. The project is made up of a series of case studies of changes. Three examine simplifying phonological changes: the rise of svarabhakti (epenthetic) vowels, the change of /hv/ > /kv/ and the loss of the voiceless dental fricative. A further three look at simplifying morphological changes: the loss of 1.sg. verbal agreement, the loss of lexical genitives and the loss of 1.pl. verbal agreement. In each case study a large dataset from many documents is collected and used to map the progression of the change in space and time. The social background of document signatories is also used to map the progression of the change through different social groups. A variety of different patterns emerge for the different changes examined. Some changes spread by contagious diffusion, but many spread by hierarchical diffusion, jumping first between cities before spreading to the country at large. One common theme which runs through much of the findings is that dialect contact within the North Germanic language area seems to have played a major role: many of the different simplificatory changes may first have spread into Norwegian from Swedish or Danish. Although these findings do not exactly match the simple predictions originally proposed from the sociolinguistic typological theory, they are potentially consistent with a more nuanced account in which the major centres of contact and so simplifying change were in Sweden and Denmark rather than Norway.
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Goggins, Joe. "Distributing real time data from a multi-node large scale contact center using CORBA." [Denver, Colo.] : Regis University, 2007. http://165.236.235.140/lib/JGoggins2007.pdf.
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Keil, Tina. "Capturing everyday contact : perceptions, experiences and measurement of everyday intergroup contact in public and private settings." Thesis, University of Exeter, 2017. http://hdl.handle.net/10871/32118.
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Increasingly, culturally and ethnically diverse environments provide an abundance of ordinary, everyday intergroup encounters, especially in public settings---often consisting of a conglomeration of positive and negative experiences. Yet few intergroup contact studies have focused on measuring and assessing contact in public settings. Reasons for this include both theoretical and methodological considerations. However, before the impact of mundane, everyday encounters on prejudice reduction can be assessed, it is necessary to examine the following questions: (1) Which situations are perceived as intergroup contact by participants? (2) How do individuals conceptualise where the boundaries for contact lie? (3) How are public and private forms of contact typically experienced? (4) Do they differ in the ways researchers have assumed in the past? and (5) Which methods are most appropriate for assessing public encounters? How can memory bias, temporality and locatedness be taken into account? Using qualitative, quantitative and near-time in-the-field methods, the following research examines these aspects in both public and private settings and provides first insights into how a novel method---the Contact Logger---can be used to assess the effects of public and private contact on attitudes. A three-day diary/interview study (N=17) explored how contact is experienced, understood and conceptualised in a variety of everyday intergroup contexts. This was followed by a survey study (N=525) that examined the boundaries of what is typically perceived as being contact. Insights from both studies fed into the development of a context-aware mobile application, which enabled the capturing of near-time intergroup encounters in situ. The usability of the resulting research tool---the Contact Logger---was tested, leading to further refinements. Following an initial feasibility study (N=104) that explored contact between young and older people, a field experiment (N=112) examined intergenerational contact in public and private contexts. Data collected with the Contact Logger were analysed on aggregate and day-to-day levels, and where possible compared to traditional retrospective survey data. Results from the first two studies indicated that while traditional intergroup encounters, such as contact with family and friends, are clearly conceptualised and viewed as contact, experiences and perceptions of contact in public settings are more disparate. Moreover, effects of such contact on attitudes are dependent on the idiosyncratic meaning attributed to the specific encounter as well as past experiences. Near-time data from a field-experiment (Study 5) provided evidence that intergroup encounters reported in situ compared to retrospective survey data differed in key variables (i.e., contact quality, duration, perceived status and group typicality). Correlational analyses between near-time and retrospective measures showed less correspondence than expected. Further, additional day-to-day analyses revealed that attitudes towards older people were less positive during weekends than weekdays, indicating that attitudes may be more dynamic than previously thought. Findings, as well as the different methodological and theoretical approaches, are critically discussed. Finally, a broad range of further applications for the Contact Logger are presented and important limitations are discussed.
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Melendez, Castillo Maria Georgina. "The effects of acid contact time and rock surfaces on acid fracture conductivity." Thesis, [College Station, Tex. : Texas A&M University, 2007. http://hdl.handle.net/1969.1/ETD-TAMU-1956.
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Zielke, Hanno [Verfasser]. "Time-related alterations and other confounding factors in direct sediment contact tests / Hanno Zielke." Aachen : Hochschulbibliothek der Rheinisch-Westfälischen Technischen Hochschule Aachen, 2011. http://d-nb.info/1014298180/34.
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Young, Riki G. "Effect of organic matter and contact time on the sorption and bioavailability of chlorophenols." Thesis, This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-12042009-020047/.
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Giachritsis, Christos Dimitrios. "Estimating time-to-contact from retinal flow : the roles of global and local expansion." Thesis, University of Birmingham, 1999. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.369348.
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Göktuğ, Gökhan. "Real-time non-contact measurement and analysis for the control of distortion during welding." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/37748.
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Mu, Yan, and Yan Mu. "Slurry Mean Residence Time Analysis and Pad-Wafer Contact Characterization in Chemical Mechanical Planarization." Diss., The University of Arizona, 2016. http://hdl.handle.net/10150/621459.
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This dissertation presents a series of studies related to the slurry mean residence time analysis and the pad-wafer contact characterization in Chemical Mechanical Planarization (CMP). The purpose of these studies is to further understand the fundamentals of CMP and to explore solutions to some of CMP's challenges. Mean residence time (MRT) is a widely used term that is mostly seen in classical chemical engineering reactor analysis. In a CMP process, the wafer-pad interface can be treated as a closed system reactor, and classical reactor theory can be applied to the slurry flow through the region. Slurry MRT represents the average time it takes for fresh incoming slurry to replace the existing slurry in the region bound between the pad and the wafer. Understanding the parameters that have an impact on MRT, and therefore removal rate, is critical to maintain tight specifications in the CMP process. In this dissertation, we proposed a novel slurry injection system (SIS) which efficiently introduced fresh slurry into the pad-wafer interface to reduce MRT. Results indicated that SIS exhibited lower slurry MRT and dispersion numbers but higher removal rates than the standard pad center slurry application by blocking the spent slurry and residual rinse water from re-entering the pad-wafer interface during polishing. Another study in this dissertation dealt with the effect of pad groove width on slurry MRT in the pad-wafer interface as well as slurry utilization efficiency (η). Three concentrically grooved pads with different groove widths were tested at different polishing pressures to experimentally determine the corresponding MRT using the residence time distribution (RTD) technique. Results showed that MRT and η increased significantly when the groove width increased from 300 to 600μm. On the other hand, when the groove width increased further to 900μm, MRT continued to increase while n remained constant. Results also indicated that MRT was reduced at a higher polishing pressure while η did not change significantly with pressure for all three pads. In the last study of this dissertation, the effect of pad surface micro-texture on removal rate during tungsten CMP was investigated. Two different conditioner discs ("Disc A" and "Disc B") were employed to generate different pad surface micro-textures during polishing. Results showed that "Disc B" generated consistently lower removal rates and coefficients of friction than "Disc A". To fundamentally elucidate the cause(s) of such differences, pad surface contact area and topography were analyzed using laser confocal microscopy. The comparison of the pad surface micro-texture analysis on pad surfaces conditioned by both discs indicated that "Disc A" generated a surface having a smaller abruptness (λ) and more solid contact area which resulted in a higher removal rate. In contrast, "Disc B" generated many large near-contact areas as a result of fractured and collapsed pore walls.
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Rubin, Ori. "Contact between parents and adult children: The role of time constraints, commuting and automobility." Elsevier, 2015. https://publish.fid-move.qucosa.de/id/qucosa%3A72786.
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Recent developments suggest that the need for contact between parents and adult children is expected to grow, while paid labour is re-organized to include more flexible work schedules and locations. In parallel we view a pressure to increase sustainable mobility through reducing car driving. Against this background, this paper addresses the question: to what extent the frequency of contact between parents and their adult children living out of home is associated with time allocated to work, including commuting time, and with automobility? Face-to-face and telecommunication based contact is considered. Regression analysis of survey data collected in the Netherlands was performed and results suggest that face-to-face contact was significantly associated with work and commute duration, car ownership, car commuting and distance. Telecommunication based contact was mainly associated with work duration, degree of urbanization and distance. Automobility seemed to be more important for women than for men. The policy implication is a potential trade-off between policies that aim at strengthening sustainable mobility behaviour and policies that lead to an increase in the reliance on informal care.
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Wadhwa, Navish. "Non-coalescence of Jets." Thesis, Virginia Tech, 2012. http://hdl.handle.net/10919/42636.
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Contrary to common intuition, free jets of fluid can ``bounce'' off each other on collision in mid-air, through the effect of a lubricating air film that separates the jets. While there has been much work on coalescing jets of fluid and non-coalescence in other systems like drop-drop, drop on a bath, jet on a bath, non-coalescence of fluid jets has been little studied. A simple experimental setup was developed to stably demonstrate and study the non-coalescence of jets upon collision. This thesis presents the results of an experimental investigation of oblique collision between two fluid jets. The transition from bouncing to coalescence of jets is examined for various jet sizes and angles. Results indicate that the transition from bouncing to coalescence can be rationalized in terms of critical value of the dimensionless parameter Normal Weber Number, which represents the ratio between inertial and surface tension forces. A parametric study of the characteristic of bouncing jets, conducted by varying the nozzle diameter, jet velocity, angle of inclination and fluid viscosity reveals the scaling laws for the quantities involved such as contact time. These scaling laws help us in elucidating the role of various physical forces at play such as viscous stresses, capillary force and inertia<br>Master of Science
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Dinh, Phuong Mai. "Time-dependent density functional theory applied to clusters and molecules in contact with an environment." Habilitation à diriger des recherches, Université Paul Sabatier - Toulouse III, 2009. http://tel.archives-ouvertes.fr/tel-00981941.
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We present recent theoretical and methodological explorations on the dynamics of sodium clusters in the framework of Time-Dependent Density Functional Theory (TDDFT), coupled non-adiabatically to Molecular-Dynamics (MD). In particular, a hierarchical approach, in the spirit of Quantum-Mechanical/Molecular-Mechanical methods, has been developed for the description of metal clusters in interaction with a dynamically polarizable substrate, as rare gases or MgO. Numerous examples of application of this approach (Na clusters in or on Ar substrate, Na clusters deposited on MgO; optical response, dynamical deposition, laser irradiation, ...) are reviewed. We also briefly discuss complementing research activities. Formal developments on the Self-Interaction Correction issue in DFT and TDDFT are discussed in a word. We have furthermore extended our TDDFT-MD theory to the case of organic (C, N, O, H made) systems and a few examples of investigated dynamical processes are presented. Recent calculations of photoelectron angular distributions of free metal clusters are reported as well. We finally sketch with some perspectives for the years to come.
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Hossain, Mian Bazle. "Assessment of family planning outreach workers' contact and contraceptive use dynamics in rural Bangladesh using multilevel modelling." Thesis, University of Southampton, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.340527.
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Reeder, Patrick F. "Infinitesimals for Metaphysics: Consequences for the Ontologies of Space and Time." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1343683113.
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Can, Van Hao. "Processus de contact sur des graphes aléatoires." Thesis, Aix-Marseille, 2016. http://www.theses.fr/2016AIXM4709/document.
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Le processus de contact est l'un des systèmes de particules en interaction les plus étudiés. Il peut s'interpréter comme un modèlepour la propagation d'un virus dans une population ou sur un réseau. L'objectif de cette thèse est d'étudier la relation entre la structure locale du réseau et le comportement global du processus sur le réseau tout entier.Le cadre typique dans lequel on se place est celui d’une suite de graphes aléatoires $(G_n)$ convergeant localement vers un graphe limite $G$.On étudie alors le comportement asymptotique du temps d’extinction $tau_n$ du processussur $G_n$; lorsqu’initialement tous les individus sont infectés. Nous montrons sur plusieurs exemples qu’il existe unetransition de phase lorsque $lambda$ - le taux d'infection du processus - traverse une valeur critique $ lambda_c (G)$, qui ne dépend que de $G$.Plus précisément, pour certains modèles de graphes aléatoires comme le modèle de configuration, le graphe d'attachement préférentiel, le graphe géométrique aléatoire, le graphe inhomogène, nous montrons que $ tau_n $ est d'ordre soit logarithmique soit exponentiel; selon que $ lambda$ est soit inférieur ou supérieur à $lambda_c (G) $.De plus, dans certains cas, nous montrons des résultats de métastablité: en régime sur-critique, $ tau_n $ divisé par son espérance converge en loi vers une variable aléatoire exponentielle de moyenne $1$, et la densité des sites infectés reste stable (et non nulle) sur une période de temps d’ordre typiquement $tau_n$<br>The contact process is one of the most studied interacting particle systems and is also often interpreted as a model for the spread of a virus in a population or a network. The aim of this thesis is to study the relationship of the local structure of the network and the global behavior of the contact process (the virus) on the whole network. Let $(G_n)$ be a sequence of random graphs converging weakly to a graph $G$. Then we study $tau_n$, the extinction time of the contact process on $G_n$ starting from full occupancy. We prove in some examples that there is a phase transition of $tau_n$ when $lambda$ - the infection rate of the contact process crosses a critical value $lambda_c(G)$ depending only on $G$. More precisely, for some models of random graphs, such as the configuration model, preferential attachment graph, random geometric graph, inhomogeneous graph, we show that $tau_n$ is of logarithmic (resp. exponential) order when $lambda < lambda_c(G)$ (resp. $lambda < lambda_c(G)$). Moreover, in some cases we also prove metastable results: in the super-critical regime, $tau_n$ divided by its expectation converges in law to an exponential random variable with mean $1$, and the density of the infected sites is stable for a long time
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Bäckström, Nilsson Wilma. "Carbon Filters for Drinking Water Treatment – How Flow Rate and Empty Bed Contact Time Influence the Performance." Thesis, KTH, Kemiteknik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-298356.
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Dricksvatten är en essentiell del av ett hållbart samhälle. Därför är det viktigt att säkerställa säkert dricksvatten genom fungerande vattenreningsverk. En viktig förorening att behandla är NOM, som i sig är ofarligt men som kan producera farliga föroreningar. En teknik som används för behandling av NOM är kolfiltrering. Hur ökad flödeshastighet och ökad kontakttid påverkade kolfiltrens effektivitet undersöktes vid dricksvattenreningsverket Norrvatten. De undersökta parametrarna var partiklar, ultraviolett absorbans vid 254 nm, turbiditet, konduktivitet, fluorescent löst organiskt material, totalt organiskt kol, kemisk syreförbrukning, odlingsbara mikroorganismer och lukt. Tre kolfilter studerades vid olika flödeshastigheter; 190, 220, 250 och 280 L/s under ett dygn var. Samtidigt hade två filter ökad kontakttid på 60 och 76 % under sex veckor, medan ett filter fortsatte med den vanliga flödeshastigheten på 190 L/s. Utgående vatten från filtren analyserades för att se om dessa ändringar hade någon effekt på vattenreningen. Denna preliminära studie fann ingen signifikant effekt på kolfiltreringens rening på grund av ökad flödeshastighet eller uppehållstid. Detta kan vara en indikation på att kolfiltreringen kan hantera en framtida flödesökning och därmed vara en väsentlig del av en framtida expansionen av vattenreningsverket. De tecken som visade på att kolfiltren påverkades av ökningen av flödeshastigheter kunde förklaras av fluktuationer i inkommande vatten och skillnader mellan de olika filtren. I framtiden bör effekten av inkommande vatten studeras i detalj. En mer ingående analys av både inkommande och utgående vatten till kolfiltren bör utföras, där provtagning sker oftare för att bättre förstå fluktuationerna i inkommande föroreningskoncentrationer. Dessutom bör testerna upprepas för att se hur reningen skiljer sig från dag till dag. Hur kolfiltren hanterar ökade flödeshastigheter över längre tidsperioder bör också undersökas vidare.<br>Drinking water is an essential part of a sustainable society. In the future, the demand for drinking water will increase and contaminants in the water sources are also predicted to increase. Therefore, it is essential to ensure safe drinking water through functioning drinking water treatment plants (DWTPs). One important contaminant to treat is natural organic matter (NOM), which is harmless in itself but can produce harmful products. One technique to use for treating NOM is carbon filters (CFs). The effect of increased flow rate and increased empty bed contact time (EBCT) on the CF efficiency was investigated at a DWTP. The investigated parameters were particles, ultraviolet absorbance at 254 nm, turbidity, conductivity, cultivable microorganisms, fluorescent dissolved organic matter, total organic carbon, chemical oxygen demand, and odour. Three CFs were studied at different flow rates; 190, 220, 250, and 280 L/s for 24 hours each. Additionally, two filters had increased EBCT of 60 and 76 %, while one filter continued with the regular flow rate of 190 L/s for six weeks. Outgoing water from the filters was analysed to see if the change had any effect on the DWTP. This preliminary study did not find any significant effect on the CF treatment caused by increased flow rate or EBCT. This could be an indication that the CFs can handle a future increase in flow rate and thus be an essential part of a future expansion of the DWTP. The indications of CFs being affected by the increase in flow rates for some of the parameters could be explained by fluctuations in incoming water or differences between the separate filters. In the future, a more thorough analysis of both incoming and outgoing water to the CFs should be done, where sampling occurs more frequently to better understand the fluctuations in incoming contaminant concentrations. The measurements should also be repeated to see how the treatment differs from day to day. How the CFs handle increased flow rates over longer time periods should also be investigated further.
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WILSON, GREGORY. "ANAEROBIC/AEROBIC BIODEGRADATION OF PENTACHLOROPHENOL USING GAC FLUIDIZED BED BIOREACTORS: OPTIMIZATION OF THE EMPTY BED CONTACT TIME." University of Cincinnati / OhioLINK, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1018531262.
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Doyen, David. "Numerical methods for dynamic contact and fracture problems." Phd thesis, Université Paris-Est, 2010. http://tel.archives-ouvertes.fr/tel-00596029.
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The present work deals with the numerical solution of dynamic contact and fracture problems. The contact problem is a Signorini problem with or without Coulomb friction. The fracture problem uses a cohesive zone model with a prescribed crack path. These problems are characterized by a non-regular boundary condition and can be formulated with evolutionary variational inequations or differential inclusions. For the numerical solution, we combine, as usual in solid dynamics, a finite element discretization in space and time-integration schemes. For the contact problem, we begin by comparing the main methods proposed in the literature. We then focus on the so-called modified mass method recently introduced by H. Khenous, P. Laborde et Y. Renard, for which we propose a semi-explicit variant. In addition, we prove a convergence result of the space semi-discrete solutions to a continuous solution in the frictionless viscoelastic case. We also analyze the space semi-discrete and fully discrete problems in the friction Coulomb case. For the dynamic fracture problem, using a fully explicit scheme is impossible or not robust enough. Therefore, we propose time-integration schemes where the boundary condition is treated in an implicit way. Finally, we present and analyze augmented Lagrangian methods for static fracture problems
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Knudsen, Bernard. "A Rheological Examination of Polymer Composites: Including Functionalized Carbon Nanotubes, Viable Polyurethane Alternates, and Contact Lens Hydrogels." Scholar Commons, 2013. http://scholarcommons.usf.edu/etd/4522.
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From medicine to aerospace, innovation in multiple fields will not occur without addressing current questions that still exist in polymer behavior and manipulation. This dissertation represents the research carried out over the course of three separate experiments using rheometry as the key technique to explore the behavior of polymer composites. In all three studies, polymer composites were investigated for changes to their known physical properties caused through the addition of a filler or functionalization.
Chapter Two examines the possibility of enhancing poly(4-methyl-1-pentene) through the use of soluble carbon nanotubes. In this series of experiments, carbon nanotubes were covalently functionalized using reductive alkylation with a dodecyl group to render them easily soluble in the same organic solvents as low molecular weight poly(4-methyl-1-pentene). The polymer and the functionalized nanotubes were dissolved together in carbon tetrachloride then the solvent is removed leaving the functionalized nanotubes uniformly dispersed in the polymer matrix. The composites were then compression molded and the changes to the physical properties were explored. The functionalized nanotube filler generally acted to plasticize the samples producing transparent but colored polymers. The samples had a lower modulus and glass transition which was the opposite found by Clayton et al. using sonicated pristine carbon nanotubes.
Polyurethanes have a growing significance in the biomedical field, and we explore the possibility fine tuning the properties of a polyurethane for such uses in Chapter Three. Here, self healing Polycarbonate polyurethanes (PCU) were synthesized with two different soft segments, Nippollan 964 and T-5652, and characterized with dielectric analysis (DEA), differential scanning calorimetry (DSC) and rheometry. The extra methyl group acted to produce a crystalline-like ordered hard segment that caused the 964 PCU to become Arrhenius in the glass transition region where the 5652 PCU had followed WLF behavior. Results showed the pendent methyl group acted to impart a crystalline-like character to the 964 PCU making it a candidate for applications that would be suited to a stiffer polymer.
In Chapter Four we explore the possibility of increasing the wearability and comfort of contact lenses through increased hydration. The hydrogels 2-hydroxyethylmethacrylate (HEMA) and glycidyl methacrylate (GMA) solutions were created in three concentrations; neat, 50/50 and 60/40. Into these samples [Cu2({μ2-CO2}R)4(axial)2] (Cu(II) 4-hydroxybenzoic acid (MHBC) were dissolved 0.05% by weight. The samples were then polymerized via UV polymerization and compression molded. The experiments performed included penetration resistance , water absorption, micro hardness and glass transition. Addition of the MHBC acted to increase the water uptake of the samples but also reduced their ability to withstand mechanical penetration. With further study into crosslinking of the polymers, the MHBC could show promise in increasing hydration for commercial use.
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Hodges, Mandi. "Calling time : a discursive analysis of telephone calls to an alcohol helpline." Thesis, Loughborough University, 2007. https://dspace.lboro.ac.uk/2134/7994.
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This thesis takes Discursive Psychology as its main theoretical influence. Drawing on the resources of Discursive Psychology and utilising analytic tools provided by Conversation Analysis, these principles are applied to the study of addiction, and specifically alcohol problems. The data explored are telephone calls to an alcohol helpline. Four analytic chapters are presented. The first focuses on the concept of loss of control over drinking, identifying features of how this concept is constructed in talk and suggests possible functions of control talk for both callers and Advice Workers. The second analytic chapter examines how Advice Workers respond to callers' professed impaired control over their drinking and I demonstrate that embedded in discursive sequences of problem formulation and advice giving are issues of agency, accountability and responsibility. The thesis moves on to explore the role of knowledge in calls to an alcohol helpline and the analysis reveals that both the expert status of the Advice Worker and the speciality of the topic are co-constructed between the speakers on the helpline. The final analytic chapter features just one telephone call and demonstrates the application of such an analysis for alcohol service providers. The thesis ends with a discussion of the main overall findings and the implications of the research for clinical practice. I close by arguing that initial agency contact is a very important site of study and recommend that this should be explored utilising naturally-occurring talk.
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Waizenegger, Wolfgang [Verfasser], Peter [Gutachter] Eisert, Ralf [Gutachter] Reulke, and Thomas [Gutachter] Sikora. "Real-time 3D-based Virtual Eye Contact for Video Communication / Wolfgang Waizenegger ; Gutachter: Peter Eisert, Ralf Reulke, Thomas Sikora." Berlin : Humboldt-Universität zu Berlin, 2019. http://d-nb.info/1192752872/34.
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Worp, Everardus Cornelis Johannes van der. "Corneal desiccation in rigid gas permeable contact lens wear time to deal with 3- and 9-o clock staining /." Maastricht : Maastricht : Universitaire Pers ; University Library, Universiteit Maastricht [host], 2008. http://arno.unimaas.nl/show.cgi?fid=14422.
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Sander, Jacob Victor. "Vertical height estimates of pitched balls." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1576607357582938.
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Bushnell, Tyler D. "A Biomechanical Analysis of Sprinters vs. Distance Runners at Equal and Maximal Speeds." BYU ScholarsArchive, 2004. https://scholarsarchive.byu.edu/etd/217.
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In the sport of track and field, sprinting and distance running represent two major categories of athletes. Sprinting is associated with power and speed, whereas distance running focuses on the economy of movement. With distance running there are elements of sprint technique that overlap. With distance events, there comes a time near the end of the race where economy gives way to speed. If the distance runners knew how to alter their technique in a way to become more sprint-like, this process could possibly be more successful. PURPOSE: This study compared the differences in technique between sprinters and distance runners while running at equal and maximal speeds. METHODS: Subjects for the study consisted of 10 Division I collegiate distance runners, 10 Division I collegiate sprinters, and 10 healthy non-runners. The subjects performed two tests, with each consisting of a 60 meter run completed on the track. Test 1 was run at a pace of 5.81 m/s (4:37 min/mile), while Test 2 was completed at maximal speed. Video footage of each trial was collected at 180 Hz, monitoring hip, knee, thigh, and shank positions, as well as stride length, and contact time. RESULTS: Significant differences (p < .05) between the sprint and distance groups at maximal speed were found in the following areas: speed, minimum hip angle, knee extension at toe-off, stride length, contact time, and the position of the recovery knee at touchdown. Sprinters and distance runners exhibited a significantly lower minimum knee angle than those in the control group. Significant differences between the sprint and control group existed at the minimum hip angle, speed, stride length, contact time, and the position of the recovery knee at touchdown. Regarding the paced trial, the sprinters and distance runners showed significant difference concerning the minimum hip angle, center of mass at touchdown, and recovery knee at touchdown. Sprinters differed significantly from the control group in contact time, the center of mass at touchdown and the position of the recovery knee at touchdown. CONCLUSION: As distance runners attempt to sprint, the desired adaptations do not necessarily occur. The development of economical distance form is a fairly natural process that occurs with the miles of training. Sprinting, however, is a separate, learned technique that often requires specific feedback. When attempting maximal speed, distance runners may benefit by focusing on one characteristic of technique. If knee extension at toe-off could be trained to become more sprint-like, the other characteristics unique to sprinters may follow.
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Gimenez, Renato Lucato. "Sólidos viscoelásticos: área de hemiesferas de borracha contra uma superfície de vidro." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/3/3151/tde-23052011-111849/.
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Neste trabalho estudou-se a variação da área de contato de hemiesferas de borracha contra uma superfície plana de vidro, variando-se a força de compressão aplicada, o tempo de aplicação da força e a força de separação das superfícies em contato. Os experimentos foram realizados com quatro borrachas de módulos de elasticidade 16,8, 5,77, 5,42 e 2,64 MPa e durezas de 87, 68, 57 e 44 Shore A, respectivamente. Para borrachas de dureza mais elevada, a variação da área de contato é menor para um mesmo carregamento de referência. Para borrachas com maior módulo viscoso, maior é a variação da área de contato em função do tempo de exposição e maior a força de separação entre as superfícies. Os resultados reafirmam o modelo de Jonhson, Kendall e Roberts para o contato com baixos carregamentos de esferas de borracha e contribui para o entendimento da área de contato em função do tempo de exposição ao carregamento, onde a variação chegou a 23% para a borracha de maior módulo viscoso.<br>Contact area variation and separation forces of rubber hemispheres against a flat glass plate were studied with increasing normal forces and load exposure time. The experiments were performed on four different rubbers with Youngs modulus of 16.8, 5.77, 5.42 e 2.64 MPa and hardness of 87, 68, 57and 44 Shore A, respectively. For higher hardness rubbers, the contact area variation is smaller for the same load parameters. For higher viscous modulus rubber, the contact area variation over time is higher and it is also higher the surface separation force required. The results found are in agreement with Johnson, Kendall and Roberts model for the contact at low loads of rubber spheres and it does a contribution for the understanding of contact area due to load exposure time where variation reached up to 23% for the higher viscous modulus rubber.
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Zhao, Litao. "Using a Tracer Study to Determine the Disinfectant Contact Times for the Clarifiers in the City of Carbondale Water Treatment Plant." Available to subscribers only, 2009. http://proquest.umi.com/pqdweb?did=1967805041&sid=1&Fmt=2&clientId=1509&RQT=309&VName=PQD.
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Banov, Ivan K. "The Production of Voice Onset Time in Voiceless Stops by Spanish-English Natural Bilinguals." BYU ScholarsArchive, 2014. https://scholarsarchive.byu.edu/etd/4340.
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This study analyzes the production of Voice Onset Time (VOT) of natural Spanish-English bilinguals. VOT is a linguistic characteristic that measures the amount of aspiration occurring after the release of a stop consonant. In terms of VOT, English stop consonants differ substantially from their Spanish equivalents. This study analyzes whether or not natural bilinguals produce VOTs that approximate VOTs of monolingual speakers of each language. Participants completed two surveys to quantify their linguistic dominance in English and Spanish. They were then recorded performing similar speaking tasks in both languages. The conclusions show that natural bilinguals do not produce their English or Spanish VOTs within the monolingual norms defined in previous studies. If conclusions were to be drawn solely from this data, then the participants would theoretically have no monolingual-like language production of VOT. There is also no correlation between language dominance scores and production of VOT. These results support the conclusion that a natural bilingual is not the equivalent of two natural monolingual speakers. Significant correlations exist between VOT production and gender, age of learning English, and amount of time spent watching TV in each language. Another interesting conclusion is that many of the participants score more Spanish-dominant when a survey is given in Spanish and more English-dominant when the very same survey is given in English. This shows that even the language of a survey may skew responses slightly.
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Wiechern, Beth Justina. "Analysis of breathing during oral reading by young children with and without asthma using non-contact respiratory monitoring methods : a preliminary study of task and reading difficulty effects." Thesis, University of Canterbury. Health Sciences, 2014. http://hdl.handle.net/10092/10202.
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The aim of this research was to investigate the breathing patterns of children aged 5-9 years with asthma as they read aloud stories of increasingly difficulty. Participants were 11 children diagnosed with moderate to severe asthma recruited from an out-patient clinic and 11 gender- and age-matched controls recruited from local schools.
Non-contact respiratory monitoring methods were employed to yield acoustic recordings during three non-reading tasks and three reading aloud tasks which increased in difficulty. Measurements included breathing rate, pause time in speech, and time ratio between inspiration between inspiration and expiration (I/E ratio). Pauses that occurred during the reading tasks were classified as either occurring at grammatical junctions where pausing during oral reading would be expected, or at ungrammatical junctions, where pausing was associated with either needing to breath, a reading mistake and/or upon recognition of an unknown word. The acoustic measures were recorded using a free audio editor and recorder programme (Audacity version 2.0.3’) on a Notebook laptop with an inbuilt microphone.
The main result indicated that 82% of children with asthma breathed more slowly when reading books that were difficult for them, and this was negatively associated with asthma severity (p=0.046). The findings demonstrated that children with asthma appear to cope when reading more difficult materials by breathing more slowly, pausing for longer ([F(1, 16) = 5.454, p = 0.033]) and increasing expiration time.
The current research is the first of its kind and provides a base for future studies to investigate the relationship between breathing and the reading of children with asthma. Questions remain whether this relationship is related to low achievement in reading. Future research to confirm, disconfirm or otherwise is necessary to add to the sparse literature on the breathing of children with asthma while reading aloud.
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Ono, Keita [Verfasser], Heinz [Akademischer Betreuer] Ulbrich, and Bodo [Akademischer Betreuer] Heimann. "Development of an XFEM based Adaptive Contact Model for Telepresence Systems with Time Delay / Keita Ono. Gutachter: Bodo Heimann. Betreuer: Heinz Ulbrich." München : Universitätsbibliothek der TU München, 2011. http://d-nb.info/1019588322/34.
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Dzeaye, Ngah Veranyuy. "Prolactin and testosterone levels in first-time fathers with skin-to-skin contact with their infants soon after birth by caesarean section." Master's thesis, University of Cape Town, 2014. http://hdl.handle.net/11427/5939.
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Di, Stasio Jean. "The CD-Lagrange scheme, a robust explicit time-integrator for impact dynamics : A new singular mass formulation, and an extension to deformable-deformable contact." Thesis, Lyon, 2021. http://www.theses.fr/2021LYSEI029.
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Les pneumatiques sont complexes à simuler car les matériaux y sont hétérogènes, incompressibles et non-linéaires. De plus la géométrie descend jusqu’à l’échelle millimétrique pour les sculptures de la bande de roulement, ce qui requiert un maillage fin. Le modèle éléments finis présente donc un grand nombre de degrés de liberté, reliés par des équations non-linéaires. En dynamique, la simulation est d’autant plus compliquée avec des chocs. Néanmoins elle est cruciale dans le processus de conception pneumatique, où elle apporte une meilleur compréhension de la physique ceci sans tests réels. Les schémas explicites rendent possible les simulations de chocs, car ils résolvent facilement les non-linéarités avec un coup calcul bas. Associés à une formulation de contact précise , ils forment des schémas robustes, précis et efficaces pour la dynamique non-linéaire avec impacts. Ce travail vise à choisir et un tel schéma, et l’améliorer pour la simulation de chocs sur pneumatiques.La première partie est un benchmark identifiant le schéma CD-Lagrange. L’intégration temporelle est réalisée par le schéma de la différence centrée, et le contact imposé par multiplicateurs de Lagrange sur la vitesse. Deux possibilités d’amélioration sont identifiées. La première est d’atteindre un impact conservatif, seul instant où le schéma n’est pas symplectique. La seconde amélioration est d’étendre la formulation au contact déformable-déformable.La deuxième partie vise à atteindre la conservation de l’énergie à l’impact en adaptant la méthode de la masse singulière au CD-Lagrange. Une première formulation 1D est construite. Elle démontre une amélioration majeure du bilan d’énergie. Deux formulations 3D sont ensuite explorées.La troisième partie introduit les méthodes mortier dans le CD-Lagrange. Elles permettent de traiter un contact déformable-déformable de manière robuste, même en présence de friction et de grands glissements. Une technique d’accélération est proposée pour résoudre le problème de contact, ceci sans perte de précision<br>Tyres are complex structures to simulate. The materials are heterogeneous and incompressible with non-linear responses. The geometry goes to the millimetre scales for tread patterns. For a finite elements simulation a precise mesh is then required. The model has then a large number of degrees of freedom and non-linear material laws. In dynamics, the simulation becomes even more challenging especially with impacts. Nevertheless it is crucial in the tire design process because it brings a deeper comprehension of the tire and avoids test on real structures. The explicit time-integration make feasible the impact simulations. They handle easily the non-linearities with a very low computational cost for a time-step. Merged with a precise contact formulation, they form robust, accurate and efficient schemes for addressing impact simulations. This work aims to choose and improve an explicit scheme for non-linear dynamics with impacts. The first part is a benchmark for selecting a scheme and enhance its possibilities of improvement. The selected one is the CD-Lagrange: an explicit scheme based on central difference method, a contact enforcement by Lagrange multipliers, and a contact condition on velocity. Two mains improvements are identified and explored. Firstly, the energy conservation at impact would make the scheme symplectic for deformable bodies. Secondly the formulation must be enlarged to deformable–deformable contact. The second part aims then to achieve the conservation of energy by adapting the singular mass matrix to the CD-Lagrange. The formulation is firstly built in 1D, and shows a major improvement for the energy balance. Then two possible extensions are explored for the 3D cases. The third part presents the CD-Lagrange scheme with a mortar formulation for deformable-deformable contact. It handles with stability and accuracy large sliding and friction. An acceleration technique is proposed for solving the contact problem, without any loss of accuracy
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Beyer, Thibault. "Semi-analytical modeling of damage under contact loading : Application to heterogeneous materials." Thesis, Lyon, 2019. http://www.theses.fr/2019LYSEI045/document.
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Les pieds d’aubes de soufflantes de turboréacteurs étant soumis à des sollicitations de type fretting, l’introduction de matériaux composites dans la nouvelle génération de moteur d’avion a rendu nécessaire le développement d’outils permettant de modéliser le contact entre des matériaux hétérogènes. En particulier, le comportement tribologique et l’endommagement de ces matériaux est encore mal compris. La mise en place de méthodes numériques capable de prédire les endommagements dans le contact permettrait de mieux prédire la durée de vie des pièces en service et de garantir la sécurité des passagers. Cette thèse porte sur le développement de méthodes semi-analytiques pour la modélisation de l’endommagement dans des conditions de fretting et de roulement<br>The blade/disk interface in turbofan is subject to fretting loading. Fan blade of the new generation of aircraft engines are made of woven composite materials. The introduction of these new kind of materials create the need for a new numerical tool able to simulate the contact between heterogeneous materials. The tribological behavior and the damage mechanism associated with these kind of material are still not well understood. The developpment of new numerical tool able to model the damage in the contact area would allow to predict the life of engines parts and to guarantee the security of passengers. This PhD is about the developpment of semi-analytical methods for modeling the damage in fretting and rolling contact conditions with some applications to heterogeneous materials
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Stevens, Ben. "Short-time structural stability of compressible vortex sheets with surface tension." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:378713da-cd05-4b9a-856d-bee2b0fb47ce.
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The main purpose of this work is to prove short-time structural stability of compressible vortex sheets with surface tension. The main result can be summarised as follows. Assume we start with an initial vortex-sheet configuration which consists of two inviscid fluids with density bounded below flowing smoothly past each other, where a strictly positive fixed coefficient of surface tension produces a surface tension force across the common interface, balanced by the pressure jump. We assume the fluids are modelled by the compressible Euler equations in three space dimensions with a very general equation of state relating the pressure, entropy and density in each fluid such that the sound speed is positive. Then, for a short time, which may depend on the initial configuration, there exists a unique solution of the equations with the same structure, that is, two fluids with density bounded below flowing smoothly past each other, where the surface tension force across the common interface balances the pressure jump. The mathematical approach consists of introducing a carefully chosen artificial viscosity-type regularisation which allows one to linearise the system so as to obtain a collection of transport equations for the entropy, pressure and curl together with a parabolic-type equation for the velocity. We prove a high order energy estimate for the non-linear equations that is independent of the artificial viscosity parameter which allows us to send it to zero. This approach loosely follows that introduced by Shkoller et al in the setting of a compressible liquid-vacuum interface. Although already considered by Shkoller et al, we also make some brief comments on the case of a compressible liquid-vacuum interface, which is obtained from the vortex sheets problem by replacing one of the fluids by vacuum, where it is possible to obtain a structural stability result even without surface tension.
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Rogge, Matthew Douglas. "In-process sensing of weld penetration depth using non-contact laser ultrasound system." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/31698.
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Thesis (Ph.D)--Mechanical Engineering, Georgia Institute of Technology, 2010.<br>Committee Chair: Ume, Charles; Committee Member: Chen, Ye-Hwa; Committee Member: Michaels, Jennifer; Committee Member: Sadegh, Nader; Committee Member: Vachtsevanos, George. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Quirt, Jill Sutherland. "Epigenetic DNA methylation is not associated with natural variation in caregiver-infant physical contact time in a cross-sectional sample of human toddlers." Thesis, University of British Columbia, 2012. http://hdl.handle.net/2429/42157.
Full textAbstract:
Background: Early infant experience has been associated with long term epigenetic modifications of gene expression and subsequent health outcomes. We questioned whether daily physical contact time shared between an infant and their caregiver as an early experience was associated with prolonged variations in the epigenetic patterns of toddlers.
Methods: We performed a second look analysis of a self-reported 3-day diary kept by 1,055 caregivers of their behaviours and interactions with their infants at 5 weeks of age. We measured the average daily physical contact time shared between the infant and caregiver and compared this across the sample. We defined high and low caregiver-infant contact groups as the upper and lower 16th percentiles. We conducted a descriptive analysis of the associated caregiver and infant behaviours with high and low contact caregiving. We then collected epithelial buccal cells from a subsample of the now 3-5 year old toddlers of the high and low caregiver-infant pairs. We collected samples for 98 toddlers (59 high contact infants, 39 low contact infants). We determined DNA methylation patterns in all toddlers using the Infinium Illumina Methylation Assay and then compared the degree of methylation at 434580 CpG sites. In addition, we compared methylation status of five genes associated with stress response pathways.
Results: Average daily caregiver-infant contact time followed a normal distribution over a large range. The mean physical contact time between caregiver-infant dyads was (± SD) 9h7m (± 2h 52m). High and low contact caregiver-infant contact pairs were defined as those who shared ≥12h 22m/day and those who shared ≤6h14m/day of physical contact respectively. There were no significant associations between the methylation patterns of the epithelial buccal cells of the toddlers and the differences in physical contact time at 5 weeks of age. There were no significant associations between the methylation status and physical contact time when controlling for gender. No differences were associated with the 5 candidate genes.
Interpretation: A difference in caregiver-infant physical contact time of at least 6hrs/day at 5 weeks of age was not associated with individual differences in epigenetic methylation patterns in the epithelial buccal cells of toddlers at 3-5 years of age.