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ibrahim, sameh mohamed. "A Transient Community for a Transient Lifestyle." VCU Scholars Compass, 2014. http://scholarscompass.vcu.edu/etd/3685.
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The project suggests an alternative means for living in Qatar. It proposes the development of a transient, floating community a man-made, transitory archipelago of floating housing units located at the ‘soon to be abandoned’ docks a short distance from the Museum of Islamic Art and the Doha Corniche. The design, through a variety of bespoke dwelling options, can provide both more and less nomadic housing to accommodate a variety of dif- ferent lifestyles and social units. Clustered around three permanent islands (containing a cultural/activity center, three adaptable ‘work-unit’ towers, and a park/commercial area), the design provides a wide set of adaptive layout patterns within which the mobile units can be arrayed. Directly plugged into the city, the community functions as a floating appendix to downtown Doha: an adaptable and flexible city-supplement that can expand or contract ac- cording to need, whether to aid in the accommodation of guests for various large-scale sporting or other events, or merely to provide an alternative locale for long or short stay visitors to Doha alike.
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Erlandsson, Jakob. "The impact of onset transient duration onperceived transient loudness : Could transient level reduction be compensated by increasing transient duration?" Thesis, Luleå tekniska universitet, Institutionen för konst, kommunikation och lärande, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-79090.
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When mixing and mastering modern music, many engineers strive for making the end product to be perceived as loud as possible without sacrificing audio quality. Achieving this will often involve reducing the dynamic range of a track through peak limiting. By reducing the level of the loudest transients, the additional headroom can be used to raise the overall level of the track. This method of maximizing loudness through transient suppression has, arguably, made it more relevant to understand the human perception of transients. By further understanding the psychoacoustical factors that plays a role in how transient loudness is perceived, engineers could hopefully achieve greater audio quality while maximizing loudness, if desirable. This paper will focus on how the signal duration of a transient will affect its perceived loudness and potentially compensate for level changes within transients. The fact that sound signals of longer duration are perceived as louder than signals of shorter duration has been proven several times in prior research. This effect is tested again, in this research, by letting participants match the loudness of several short pink noise bursts of varying durations. The noise bursts are designed to mimic the envelope of a typical snare drum transient, which makes the stimuli differ from stimuli tested in prior experiments testing the same effect. Based on the result from this experiment, each transient is normalized to be perceived as equally loud. Then, a stationary component is added to every transient to make each stimuli mimic a full typical snare drum. In a second experiment, each stimuli is then compared against each other in an ABX test to see if listeners can perceive the differences. The results from the first experiment showed that transients were perceived to be approximately 0.3 dB louder per 5 ms increase in duration. In the second experiment, listeners failed to hear the differences between stimuli when transient duration differed less than 5 ms. For differences in duration longer than this, listeners correctly identified the differences.
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Karimishad, Amir. "Transient stability-constrained load dispatch, ancillary services allocation and transient stability assessment procedures for secure power system operation." University of Western Australia. Energy Systems Centre, 2008. http://theses.library.uwa.edu.au/adt-WU2009.0028.
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[Truncated abstract] The present thesis is devoted to the development of new methods for transient stability-constrained optimal power flow, probabilistic transient stability assessment and security-constrained ancillary services allocation. The key objective of the thesis is to develop novel dispatch and assessment methods for power systems operation in the new environment of electricity markets to ensure power systems security, particularly transient stability. A new method for economic dispatch together with nodal price calculations which includes transient stability constraints and, at the same time, optimises the reference inputs to the Flexible AC Transmission System (FACTS) devices for maintaining power systems transient stability and reducing nodal prices is developed. The method draws on the sensitivity analysis of time-domain transient stability simulation results to derive a set of linearised stability constraints expressed in terms of generator active powers and FACTS devices input references. '...' The low computing time requirement of the two-point estimate method allows online applications, and the use of detailed power systems dynamic model for time-domain simulation which offers high accuracy. The two-point estimate method is integrated in a straightforward manner with the existing transient stability analysis tools. The integrated software facility has potential applications in control rooms to assist the system operator in decision making process based on instability risks. The software system when implemented on a cluster of processors also makes it feasible to re-assess online transient stability for any change in system configuration arising from switching control. The method proposed has been tested on a representative power system and validated using the Monte Carlo simulation. In conjunction with the energy market, by which forecasted load demand is met by generator dispatch, ancillary services are required in relation to control for secure system operation and power quality. The final part of the thesis has a focus on the key aspect of allocating these ancillary services, subject to an important constraint that the dispatch of the ancillary services will not impair the system security achieved in the load dispatch. With this focus and requirement, the thesis develops a new dispatch formulation in which the network security constraints are represented in the optimal determination of generator active power schedule and allocation of ancillary services. Contingencies considered include power demand variations at individual load nodes from the values specified for the current dispatch calculation. The required changes in generator active powers to meet the new load demands are represented by additional control variables in the new dispatch formulation which augment those variables in the traditional OPF dispatch calculation. Based on the Lagrange function which includes the extended set of security constraints, the formulation derives the optimality condition to be satisfied by the dispatch solution, together with the marginal prices for individual ancillary service providers and LMPs. The effects of the security constraints are investigated and discussed. Case studies for representative power systems are presented to verify the new dispatch calculation procedure.
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Maguire, N. "Transient Kinetics." Thesis, Queen's University Belfast, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.527839.
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張家榮 and Ka-wing Fredo Cheung. "Transient mediator." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2002. http://hub.hku.hk/bib/B3198633X.
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Hammond, Bryce. "Transient Motel." Master's thesis, University of Central Florida, 2013. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5640.
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“Transient Motel” is an exhibition that investigates the interactions of people and physical environments in low-income areas of Daytona Beach, Florida. The purpose of the exhibition is to raise social awareness of low-income communities among the public through visual art. Interactions between motel guests were documented as first-hand sound recordings of conversations, interviews and other activities. These recordings are projected through speakers within a constructed life-sized replica of the motel rooms in which they were recorded. Found and appropriated furniture and fixtures from the actual rooms are arranged within the replica as objects of art to familiarize the public with conditions of poverty. During my exhibition, the public is encouraged to participate by entering and exploring the replica of the motel room. The participant experiences authentic objects, sounds and smells of Daytona Beach motel rooms that have been inhabited by victims of transient poverty.?M.F.A.
Masters
Visual Arts and Design
Arts and Humanities
Emerging Media; Studio Art and the Computer
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Cheung, Ka-wing Fredo. "Transient mediator." Hong Kong : University of Hong Kong, 2002. http://sunzi.lib.hku.hk/hkuto/record.jsp?B2594924x.
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Chuthi, Noel Nelson Stima. "Current transformers transient response modelling using electromagnetic transient program (EMTP)." Master's thesis, University of Cape Town, 1997. http://hdl.handle.net/11427/19564.
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The subject of this thesis is Current Transformer Transient response study using an electromagnetic Transient program (EMTP). Current transformers are considered eyes for power system protection. Behaviours of protection systems depend largely on information fed to them by instrument transformers. Ferromagnetic current transformers have for many years provided practical method of current measurement, however there are limitations associated with current transformer operation:- notably, difficult in maintaining accuracy over the full range of operating conditions, and most particularly current transformers tendency to suffer saturation of iron core during severe faults, with accompanying severe ratio or loss of output. These limitations might lead to mal operation of protective relays due to distorted inputs from current transformers particularly in transient periods. This thesis involved studying the behaviour of current transformers in both steady state and transient periods. An emphasis being put on transient periods which are very crucial in behaviour of current transformers because transformation errors are greatest in these periods. Errors in current transformer transformation might affect operation of entire protection schemes. Maloperation of current transformers in transient periods have very bad effect on relay co-ordination and worst condition might be failure of protection scheme operation altogether. Over the past decades engineers have been trying to develop a current transformer model that would represent a current transformer well in transient periods. It has proved to be rather difficult to come up with a single detailed model that would satisfy all possible conditions. This is due to non-linearity of magnetising curve and saturation effects of current transformer iron cores. The author has considered different current transformer models with their merits and demerits being highlighted. It has been shown that different current transformer models have to be used when considering different operating conditions of a current transformer in a power system. ATP-EMTP an Electromagnetic Transient Program was developed in the sixties for the study of electromagnetic transients in power systems. It has proved to be a very useful tool in this regard. The program development is still going on today to accommodate a wide application in power systems. Several components have been developed to represent different components in a power system. It is only recently that there has been a growing interest to include modelling of protective equipment. This has been accelerated by the inclusion of MODELS in the EMTP program. This thesis explores the effect of transients taking into account different conditions like transient fault currents, effects of high frequency waves and surges. Effects of different types of burdens on current transformers were explored as well. Due to limitations of EMTP, simulation results are only applicable to current transformers with ARMCO M4 oriented steel with ungapped cores. The author arrived at several conclusions. The most important conclusion is that mal operation of protective relays due to current transformer saturation can be avoided easily if proper current transformer selection is given priority in power protection design. EMTP package proved to be very useful and handy when studying transients though one has to be careful with numerical oscillations which might be present during simulations. Problems of numerical oscillations have been discussed under current transformer simulation tools.
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Kirmani, Ahmed (Ghulam Ahmed). "Femtosecond Transient Imaging." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/58402.
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Thesis (S.M.)--Massachusetts Institute of Technology, School of Architecture and Planning, Program in Media Arts and Sciences, 2010.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 59-64).
This thesis proposes a novel framework called transient imaging for image formation and scene understanding through impulse illumination and time images. Using time-of-flight cameras and multi-path analysis of global light transport, we pioneer new algorithms and systems for scene understanding through time images. We demonstrate that our proposed transient imaging framework provides opportunities to accomplish tasks that are well beyond the reach of existing imaging technology. For example, one can infer the geometry of not only the visible but also the hidden parts of a scene, enabling us to look around corners. Traditional cameras estimate intensity per pixel I(x, y). Our transient imaging camera prototype captures a 3D time-image I(x, y, t) for each pixel and uses an ultra-short pulse laser for flash illumination. Emerging technologies are supporting cameras with a temporal-profile per pixel at picosecond resolution, allowing us to capture an ultra-high speed time-image. This time-image contains the time profile of irradiance at a sensor pixel. The speed of light is relevant at these imaging time scales, and the transient properties of light transport come into play. In particular we furnish a novel framework for reconstructing scene geometry of hidden planar scenes. We experimentally corroborated our theory with free space hardware experiments using a femtosecond laser and a picosecond accurate sensing device. The ability to infer the structure of hidden scene elements, unobservable by both the camera and illumination source, will create a range of new computer vision opportunities.
by Ahmed Kirmani.
S.M.
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Smith, Daniel Patrick. "Transient bed mechanics." Thesis, University of Cambridge, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.620448.
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Shappee, Benjamin J. "The Transient Universe." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1403785567.
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Roth, Eric. "Transient heat transfer." PDXScholar, 1991. https://pdxscholar.library.pdx.edu/open_access_etds/4264.
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With the advent of the new high Tc superconductors, liquid nitrogen will be one of the preferred cryogens used to cool these materials. Consequently, a more thorough understanding of the heat transfer characteristics of liquid nitrogen is required. In our investigations we examine the transient heating characteristics of liquid nitrogen to states of nucleate and film boiling under different liquid flow conditions. Using a platinum hot wire technique, it is verified that there is a premature transition to film boiling in the transient case at power levels significantly lower than under steady state nucleate boiling conditions. It is also shown that the premature transition can be reduced or eliminated depending on the flow velocity.
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Khan, Shahbaz Javaid. "Studies on conformational changes of transient intermediate species of PYP photoreaction by transient grating and transient lens methods." 京都大学 (Kyoto University), 2006. http://hdl.handle.net/2433/144212.
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Caruso, Jeremihas Sulzbacher. "Características locais no tráfego de pacotes em redes complexas próximo ao ponto de congestionamento." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-29052014-102123/.
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Por muitos anos, a ciência tratou todas as redes como se seus relacionamentos fossem estabelecidos de forma randômica, ou seja, a maioria dos nós teriam aproximadamente o mesmo número de relacionamentos. Porém, o mapeamento de uma variedade de sistemas revelou que a maioria dos nós tinha poucos relacionamentos, enquanto alguns nós têm uma grande quantidade de conexões. Processos microscópicos dinâmicos e estatísticos são duas facetas de sistemas complexos, que estão intimamente ligadas, e a compreensão da sua interdependência é importante tanto para a previsão quanto planejamento estratégico. Os exemplos mais proeminentes incluem o ruído do tráfego em redes de comunicação, sinais ruidosos em sistemas desordenados e auto-organizados, e as séries temporais das flutuações dos preços nos mercados financeiros. Neste trabalho foram analisadas não apenas características globais do tráfego de pacotes em redes complexas, como a presença ou não de congestionamento na rede como um todo, mas também as características locais (isto é, de roteadores específicos) do tráfego no ponto de transição entre a fase livre e a fase de congestionamento. Os resultados mostram, entre outros, que a transição de um estado livre de congestionamento para o estado congestionado de um nó ocorre quando o coeficiente de detrended fluctuation analysis da série temporal do número de pacotes na fila de espera do nó é próximo do valor crítico de 1.For many years the science networks all treated as if their relationships were set at random, that is, most of us have approximately the same number of relationships. However, the mapping in a variety of systems revealed that most of us had a few relationships, while some of us have a lot of connections. Dynamic and statistical microscopic processes are two facets of complex systems, which are closely linked, and understanding of their interdependence is important both for predicting as strategic planning. Prominent examples include traffic noise in communication networks, noisy signals in disordered systems and self-organized, and the time series of price fluctuations in financial markets. This work analyzed not only the overall characteristics of package traffic in complex networks and the presence or absence of congestion on the network as a whole, but also the local characteristics (ie, specific routers) of the traffic at the point of transition from the free phase, and congested phase. The results show, among others, that the transition from free to congested traffic in a node happens when the detrended fluctuation analysis coefficient of the time series of the number of waiting packets is close to the critical value of 1.
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Rocha, Pitta Jorge Antonio Fernandes da. "Transient detection using wavelets." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1995. http://handle.dtic.mil/100.2/ADA297697.
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Thesis (M.S. in Electrical Engineering) Naval Postgraduate School, March 1995."March 1995." Thesis advisor(s): Ralph D. Hippenstiel, Monique P. Fargues. Includes bibliographical references. Also available online.
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Wirth, Adrian. "Attosecond transient absorption spectroscopy." Diss., lmu, 2011. http://nbn-resolving.de/urn:nbn:de:bvb:19-140120.
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Lee, Chien-Hsing. "Wavelet-based transient analysis." Diss., Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/14713.
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Petty, David Matthew. "Transient photoconduction in phthalocyanines." Thesis, University of Nottingham, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.277939.
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Dutton, Richard John. "Modelling transient storage processes." Thesis, University of Sheffield, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.419618.
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James, Huw William. "Transient Markov decision processes." Thesis, University of Bristol, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.430192.
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Athanasiadis, Panos J. "Teleconnections and transient eddies." Thesis, University of Reading, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.493965.
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The subject of this thesis is the dynamics of teleconnections and mid-latitude stationary eddies, key components of the structure and variability of the extratropical general circulation. Deepening our understanding of their dynamics is of particular importance in the context of predicting and explaining possible climate changes.
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Perry, Samuel C. "Transient studies at microelectrodes." Thesis, University of Southampton, 2015. https://eprints.soton.ac.uk/387227/.
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Transient studies of electrochemical systems at microelectrodes allow analysis under rapid mass transport conditions. The small active area allows rapid resolution of charging currents, giving access to meaningful information even at short times. Sampled current voltammetry at microelectrodes (MSCV) is a multistep technique whereby data is collected from a series of potential step experiments along the redox wave of interest. Varying the sampling time allows comparison of how a reaction proceeds at varying timescales, whilst simultaneously showing the potential dependence. Selection of an appropriate sampling time tunes the rate of mass transport to give quasireversible conditions, allowing facile kinetic analysis using quasireversible models. Application to the oxygen reduction reaction (ORR) revealed unreasonably large currents at short times. This work suggests that pre-adsorbed oxygen at the electrode surface is responsible. The presence of the pre-adsorbed oxygen was confirmed by its direct reduction in argon purged solution, and its strong dependence on the metal substrate. The resultant peak potentials were used to calculate the binding energies of varying metals towards oxygen (ΔG₀), which are in excellent agreement with the literature. This is useful, as ΔG₀ is a popular descriptor for oxygen reduction activity. Once the pre-adsorbed oxygen is consumed, MSCVs for the ORR can be used for standard kinetic analysis using Tafel or Koutecky-Levich analyses, with the advantage of the electrode being oxide free before each data point is recorded.
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Vasquez, Julia Barbara Ann. "Constructing a Transient Permanence." Thesis, Virginia Tech, 2017. http://hdl.handle.net/10919/78261.
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A residence hall is a temporary home. Yet, it can be the most impactful campus environment on a student's education and life. From lifelong friendships to retention rates, residence halls affect students as many experience their first opportunity to express their individuality and personal responsibility. No study can conclusively determine that one residence hall type is better than another. Rather, it is a hall's overall gestalt that determines student satisfaction and a positive perception of community.
The question of my thesis explores how residence hall architecture can anticipate its role as an inspiring distraction to the individual that provokes interaction, engagement, and community as a building type that is not quite transient and not quite permanent.Master of Architecture
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Almeida, Telmo David Pelicano. "EDFA transient regime characterization." Master's thesis, Universidade de Aveiro, 2011. http://hdl.handle.net/10773/7256.
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Mestrado em Engenharia FísicaO presente trabalho propõe-se a relatar o desenvolvimento de duas interfaces gráficas para a simulação dos modelos estacionário e dinâmico de um amplificador de fibra dopada com érbio (EDFA), bem como a caracterização experimental do regime transiente em EDFAʼs originado por tráfego em modo de rajada. Relata também a validação experimental bem sucedida do modelo dinâmico no que toca a simular os referidos perfis de tráfego. É também descrita a avaliação experimental bem sucedida do impacto na geração de transientes de parâmetros importantes como o tamanho dos pacotes e o intervalo de tempo entre si, e a potência da bomba de um EDFA.
This work relates the development of two graphical user interfaces for the simulation of both the dynamic and steady state models of an erbium doped fiber amplifier (EDFA), as well as the experimental characterization of the transient regime of EDFAs when amplifying bursty traffic profiles. The experimental validation of the numeric model for simulating bursty traffic is also reported. Experimental assessment of important parameters such as packet length, idle time duration and pump power was also performed and reported.
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Keane, Evan. "The transient radio sky." Thesis, University of Manchester, 2010. https://www.research.manchester.ac.uk/portal/en/theses/the-transient-radio-sky(37c08735-cd96-4598-a8b9-2d24ef9e871d).html.
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The high time-resolution radio sky represents unexplored astronomical territory where the discovery potential is high. In this thesis I have studied the transient radio sky, focusing on millisecond scales. As such, this work is concerned primarily with neutron stars, the most populous member of the radio transient parameter space. In particular, I have studied the well known radio pulsars and the recently identified group of neutron stars which show erratic radio emission, known as RRATs, which show radio bursts every few minutes to every few hours. When RRATs burst onto the scene in 2006, it was thought that they represented a previously unknown, distinct class of sporadically emitting sources. The difficulty in their identification implies a large underlying population, perhaps larger than the radio pulsars. The first question investigated in this thesis was whether the large projected population of RRATs posed a problem, i.e. could the observed supernova rate account for so many sources. In addition to pulsars and RRATs, the various other known neutron star manifestations were considered, leading to the conclusion that distinct populations would result in a 'birthrate problem'. Evolution between the classes could solve this problem - the RRATs are not a distinct population of neutron stars. Alternatively, perhaps the large projected population of RRATs is an overestimate. To obtain an improved estimate, the best approach is to find more sources. The Parkes Multi-beam Pulsar Survey, wherein the RRATs were initially identified, offered an opportunity to do just this. About half of the RRATs showing bursts during the survey were thought to have been missed, due to the deleterious effects of impulsive terrestrial interference signals. To remove these unwanted signals, so that we could identify the previously shrouded RRATs, we developed new interference mitigation software and processing techniques. Having done this, the survey was completely re-processed, resulting in the discovery of 19 new sources. Of these, 12 have been re-detected on multiple occasions, whereas the others have not been seen to re-emit since the initial discovery observations, and may be very low burst-rate RRATs, or, isolated burst events. These discoveries suggest that the initial population estimate was not over-estimated - RRATs, though not a distinct population, are indeed numerous. In addition to finding new sources, characterisation of their properties is vital. To this end, a campaign of regular radio observations of the newly discovered sources, was mounted, at the Parkes Observatory, in Australia. In addition, some of the initially identified RRATs were observed with the Lovell Telescope at Jodrell Bank. These have revealed glitches in J1819-1458, with anomalous post-glitch recovery of the spin-down rate. If such glitches were common, it would imply that the source was once a magnetar, neutron stars with the strongest known magnetic fields of up to 10¹⁵ gauss. The observations have also been used to perform 'timing' observations of RRATs, i.e. determination of their spin-down characteristics. At the beginning of this thesis, 3 of the original sources had 'timing solutions' determined. This has since risen to 7, and furthermore, 7 of the newly discovered sources now also have timing solutions. With this knowledge, we can see where RRATs lie in period-period derivative space. The Parkes RRATs seem to be roughly classifiable into three groupings, with high observed nulling fractions - normal pulsars, high magnetic field pulsars and old, 'dying' pulsars. It seems that RRATs and pulsars are one and the same. When a pulsar is more easily detected in searches for single bright pulses, as opposed to in periodicity searches, we label it a RRAT. Such searches impart a selection effect on the parameter space of possible sources, in both nulling fraction and rotation period. In this sense, an observational setup could be designed to make any pulsar appear as a RRAT. For realistic survey parameters however, this is not the case, and the groups mentioned above seem to be the most likely to appear as RRATs. In fact, we can utilise RRAT searches to identify neutron stars, difficult to find by other means, in particular high-magnetic field pulsars, and pulsars approaching the pulsar "death valley". Some of the RRATs are well explained as being distant/weak pulsars with a high modulation index, others seem to be nulling pulsars. This highlights the incomplete knowledge of nulling behaviour in the pulsar population. It seems that there may be a continuum of nulling durations, under a number of guises, from 'nulling pulsars' to 'RRATs' to 'intermittent pulsars'. In fact this nulling may fit into the emerging picture, whereby pulsar magnetospheres switch between stable configurations.
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Gupta, Ashish Kumar. "Management of transient XML messages /." Thesis, Connect to this title online; UW restricted, 2005. http://hdl.handle.net/1773/6945.
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Gjerde, Joachim Dyrstad. "Transient Flow in Gas Transport." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for energi- og prosessteknikk, 2011. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-12992.
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Transport of natural gas to continental Europe and UK is a large portion ofNorwegian petroleum industry. The gas is mainly transported undersea inlarge-scale transport pipelines. Amount of transported gas is currently closeto maximum capacity of the pipeline network, and as a consequence the gastransport must be careful planned so that the optimal capacity can be utilized.An important tool in this planning is the use of computational method topredict the flow. Accurate computational tools is therefore of great value whenpredicting the pressures and flow rates in transient cases such as opening of avalve or shut down of a flow. This report is a part of a major research projectinitiated by Gassco, for better flow-predictions models in natural gas pipelines.A computational model based on the method of characteristics has beendeveloped. In this report the main focus is on the solution of the energy equationand introduction of this equation to an already existing code solving for pressureand mass flux. The method is verified using measured values of pressure at theinlet.Since much of the uncertainty is related to the transients, this report focuseson transient cases. The old program solving the characteristic equations using anisothermal assumption actually proves surprisingly accurate, and the additionalsolution of temperature does not significantly improve the results. The methodhowever does not provide satisfactory results at the larger transients.If large temperature gradients are imposed on the solver we see instabilities inthe flow and it affects the solution of the parameters. The Joule Thomson effectthat we have in our solution also results in a much higher drop of temperaturethan what can be measured, in case of pressure drop at the inlet.From the results we also see that the coefficient that is supposed to correctfriction factor for additional drag effects, also should be a function of pressureand/or Reynold number. If such a correlation would provide more accurateresults in the transient has not been debated, but more accurate correlation offriction depending on flow rate would probably give a more accurate result.Also worth noticing is that the method does not have a clear convergence,or reduction of error as the number of calculation points increases. It givessmaller extreme values, but average error is not reduced significantly. This isprobably a result of the reduced effect of missing convective-term as the gridhas a finer resolution and time-step decreases and the effect of loss of velocityin the characteristic becomes small.As a simple tool for calculation of gas transport in pipelines, the isothermalmethod of characteristics proves to give surprisingly accurate results. However,for more complex systems, i.e. including the temperature and variable propertiessuch as compressibility and density, finite difference methods are more versatile.Finite difference methods can be done implicit, giving a more stable solver, andits simpler to account for some of the effects such as temperature etc.iv
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Wei, Tzu-Hsiang Biotechnology & Biomolecular Sciences Faculty of Science UNSW. "Transient production of biopharmaceutical proteins." Publisher:University of New South Wales. Biotechnology & Biomolecular Sciences, 2009. http://handle.unsw.edu.au/1959.4/43708.
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The creation of stable mammalian cell lines for biopharmaceutical production often require several months, and is unfavourable for the rapid production of multiple drug candidates for screening in the early stages of development. Biopharmaceutical production by transient transfection provides a possible alternative of quickly producing these early stage drug candidates. The Epi-CHO transient expression system, which consists of a Chinese hamster ovary (CHO) cell line (CHO-T) expressing the murine polyomavirus Large T-Antigen (LT), emonstrated enhanced transient recombinant protein production. The aim of this study was to prolong transient recombinant protein prod.Jction of the Epi-CHO expression system by creating a CHO cell line expressing both LT and EBNA1 (ECHO-T). The pEBNA1-LT expression vector encoding LT and EBNA1 was constructed and transfected into CHO-K1. A total of 20 clones were isolated from the antibioticresistant pool and screened for the expression of functional LT and EBNA1. PCR analysis showed 16 of the 20 clones was positive for EBNA1 and LT DNA. Of the 16 clones, six were positive for EBNA1 and LT expression by RT-PCR. Detection of LT and EBNA1 by immunofluorescence showed positive staining for the P7-G3 clone. Western blotting suggested the P7-G3 clone was: positive for EBNA1, and clones P3-C7 and P7-E2 were positive for LT. A plasmid replication assay confirmed the expression of functional LT in all six clones. Plasmid maintenance assay confirmed clone P7-G3 as the ECHO-T clones to express functional EBNA1. The P7-G3 clone demonstrated prolonged and sustained transient recombinant protein expression when compared to CHO-T. The P7-G3 clone achieved sustained transient protein expression for 32 days in the absence of selection, the longest currently reported for CHO cells.
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Baldock, Thomas Edward. "Non-linear transient water waves." Thesis, Imperial College London, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.432369.
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Cantwell, Christopher David. "Transient growth of separated flows." Thesis, University of Warwick, 2009. http://wrap.warwick.ac.uk/3126/.
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Transient growth is quantitatively examined in two prototype separated flows using Direct Numerical Simulation (DNS). Separated flows typically exhibit regions of convective instability due to the inflectional velocity profiles inherent in the shear flow. This can lead to the transient growth of small disturbances by many orders of magnitude. After reviewing the mathematical tools and numerical techniques required, we present an analysis of transient growth in an axisymmetric pipe with a 1:2 diametral expansion. A direct method is used to calculate the optimal transient energy growth for specified time horizons and Reynolds numbers up to Re=1200, and low-order azimuthal wavenumber m. At each Re the maximum growth is in azimuthal mode m=1 and this maximum is found to increase exponentially with Re. The time evolution of optimal perturbations is presented and shown to correspond to sinuous oscillations of the shear layer. Finally, full three-dimensional DNS with the in flow perturbed with Gaussian white-noise conforms the presence of the structures determined by the transient growth analysis. The second prototype flow considered is the cylinder wake in the subcritical regime. Large energy growth is observed at Reynolds numbers close to the onset of global instability and the optimal perturbations which lead to this growth are determined. Three-dimensional spanwise perturbations are also examined and it is found that, except for short time horizons, the zero wavenumber is dominant. Furthermore, performing accurate linear and transient growth analysis is found to be highly dependent on the size of the computational domain. Adjoint eigenmodes extend far upstream of the cylinder necessitating a long in flow. More importantly, constrictions in the cross-stream direction are found to distort the basic flow, which has a substantial effect on the accuracy of the analysis. Transition in pipe flow is a topic for which there is still relatively little understanding. Pus are small regions of turbulence observed close to the transitional Reynolds number. A gradually expanding pipe is proposed as a means to effectively produce turbulent puffs and study their creation and decay.
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Yeung, Chi-keung Patrick, and 楊志強. "Transient neighborhoods and urban development." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1991. http://hub.hku.hk/bib/B31976827.
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Majus, Donatas. "Transient phenomena in femtosecond filamentation." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2014. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2014~D_20141010_114906-27198.
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In 1995 Braun and co-workers reported the observation of self-channeling of femtosecond laser pulses over 20 m in air. This first observation of femtosecond filament triggered a series of studies, which discovered an exciting physics beyond the interaction of ultrashort laser pulses with transparent dielectric media.
This dissertation aims at comprehensive study of transient spatiotemporal phenomena (space-time transformations, pulse splitting and compression, filament propagation dynamics, supercontinuum generation and multiple filamentation) that take place during self-focusing of intense femtosecond laser pulses in various self-action regimes in transparent dielectric media with instantaneous Kerr nonlinearity.
Various nonlinear optics diagnostic methods (three dimensional mapping, auto- and cross-correlation measurements, frequency resolved optical gating measurements), spatially resolved frequency spectra measurements, statistical analysis of spectral intensities and energies, numerical simulations were employed.
The dissertation addresses important issues regarding complete physical understanding of the evolution cycle of femtosecond filaments in normally dispersive media, physical nature of spatiotemporal light bullets generated by filamentation in the anomalous group velocity regime, detailed statistical aspects of supercontinuum generation, and spatiotemporal characterization of multiple filaments. Analysed factors are useful for practical applications when... [to full text]Ultratrumpiesiems šviesos impulsams sklindant skaidriose terpėse dėl jų saviveikos gali formuotis ypatingi šviesos dariniai – šviesos gijos, kurios pirmą kartą stebėtos 1995 m. Braun ir kt. Pirmuosius šviesos gijų stebėjimus sekė eilė tyrimų, kurie atskleidė įdomius femtosekundinių lazerinių impulsų saviveikos reiškinius, kartais apimančius platesnes netiesinės optikos tyrimų sritis. Šios disertacijos tikslas – išsamiai ištirti dinaminius erdvėlaikinius reiškinius (šviesos gijų sklidimą, erdvėlaikines transformacijas, impulsų skilimą ir spūdą, superkontinuumo generaciją ir daugelio šviesos gijų atsiradimą) įvairiuose intensyvių femtosekundinių lazerio impulsų saviveikos režimuose skaidriose dielektrinėse terpėse su momentiniu Kero netiesiškumu. Tyrimams naudoti įvairūs netiesinės optikos metodai (trimatė lazerinė tomografija, auto- ir kryžminės koreliacijos matavimai, dažninės skyros optinės sklendės autokoreliaciniai matavimai), erdvinės-dažninės skyros spektrų matavimas, statistinė spektrinių, energijos matavimų analizė, skaitmeninis modeliavimas. Atliktų tyrimų visuma išplečia esamas žinias apie femtosekundinių šviesos impulsų saviveiką ir netiesinių optinių sistemų dinamiką normalios ir anomalios grupinių greičių dispersijos atvejais, vedančią prie nestabilumo ir ekstremalių optinių įvykių žadinimo. Kita vertus, ištirti veiksniai naudingi praktiniuose taikymuose, kai siekiama formuoti tvarkias erdvines-laikines struktūras, žadinti ekstremalias optines bangas arba... [toliau žr. visą tekstą]
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Couturier, Nicolas. "Transient Stability During Asymmetrical Faults." Thesis, KTH, Elektroteknisk teori och konstruktion, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-160521.
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This research project has been conducted at RTE in order to study the transient stability after asymmetrical faults. When three-phase short-circuits occur in a network, almost all the electrical power is lost on the relevant line(s). Among all short-circuit types, it is the most drastic event and the issue has to be solved very quickly. But oddly, it is also the easiest problem to solve mathematically speaking. This comes from the fact that the system stays balanced, and equations can be simplified. However with line-to-ground faults this is no longer the case, and transient stability analysis becomes tricky. Until now, unbalanced situations have not been studied much. Since this kind of trouble is less serious than losing all three phases, every protection devices on the network have been sized to counter three-phase faults in time and avoid severe consequences. They will then also work for onephase problems. Despite this, there is a desire from RTE to understand – physically and mathematically – what happens when one-phase faults occur, and it is the mission behind this master thesis. First, a mathematical theoretical model was derived to examine a network’s stability without running any simulation. Then, once simulation software programs were taken in hand, several tests were run on a very simplified network, and compared with the theory developed previously. Finally, these experiments were carried out on a much larger scale. It is important to understand that, except for the theoretical model, all the results and conclusions in this document come from simulations. Even if a lot of tests and models led to them, these conclusions must be handled with care. The goal of this work was also to have a better understanding of unbalanced systems, of the Fortescue representation and thus, understand more clearly the parameters required by simulation tools like Eurostag© for future studies.Detta forskningsprojekt genomfördes hos RTE för att undersöka transientstabilitet efterosymmetriska fel. När trefasiga kortslutningar inträffar i en nätverk försvinner nästan all kraft i derelevanta ledningarna. Bland alla kortslutningstyper är detta den mest drastiska händelsen och måstelösas väldigt snabbt. Konstigt nog är det det lättaste problemet att lösa matematiskt. Detta på grundav faktumet att systemet förblir balanserat och ekvationer kan förenklas. Hursomhelst vid enfasigajordfel är detta inte längre fallet och transientstabilitetsanalys blir plötsligt svårt att räkna på. Fram tills nu har inte lösningar på obalanserade situationer studerats mycket. Eftersom denna typ avproblem är mindre allvarliga än att förlora alla tre faser, så har enheter på nätverket utformats för attmotverka trefas--‐fel snabbt och undvika allvarliga konsekvenser. Enheterna kommer då också fungeraför enfasproblem. Trots detta så finns det en önskan från RTE att förstå –fysiskt och matematiskt –vad som händer närett enfasproblem uppstår, det är det som är målet med mitt examensarbete. Först framtogs enmatematisk teoretisk modell för att examinera nätverkets stabilitet utan att köra någon simulation. Sedan med hjälp av mjukvarusimulatorer så utfördes flertalet test med den tidigare utveckladeteorin. I slutändan utfördes experimenten i en mycket större skala. Det är viktigt att förstå att, utom den teoretiska modellen, kommer alla resultat i denna rapportenfrån simuleringar. Även om flera tester och modeller ledde fram till dem, ska dessa slutsatserhanteras varsamt. Målet med detta arbete var att få bättre förståelse för obalanserade system, representationen med symmetriska komponenter och därmed, få en klarare förståelse för parametrarna som krävs avsimuleringssverktyg så som Eurostag© för framtida studier.
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Gilchrist, J. R. "Opto-thermal transient emission radiometry." Thesis, University of Strathclyde, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.381131.
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Olyabek, Zuhair. "Digital optically coupled transient recorder." Thesis, City University London, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.238838.
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Schaedlich, Mirko. "Nonlinear transient structural response analysis." Thesis, University of Southampton, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.438667.
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Berkin, J. "Transient photoconduction in amphorous materials." Thesis, University of Abertay Dundee, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.328002.
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ALVES, CARLOS FREDERICO ESTRADA. "TRANSIENT SIMULATIONS ON RADIAL DIFUSORS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 1998. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=19466@1.
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COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOREste trabalho apresenta o estudo do escoamento transiente em difusores radiais com fronteira móvel alimentados axialmente. O problema é resolvido acoplando-se a modelagem do fluido à dinâmica do movimento da palheta. Admite-se o comportamento Newtoniano para o fluido de trabalho (ar). O escoamento é considerado incompressível, laminar e isotérmico numa geometria axisimétrica. As equações de conservação são resolvidas pelo método dos volumes-finitos utilizando-se um código numérico comercial, o FLUENT, adaptado de modo a permitir que o posicionamento da fronteira móvel faça parte da solução do problema. Analise-se os casos de movimentação súbita imposta à palheta e de fluxo mássico de alimentação periódica. Resultados do comportamento temporal da força axial do fluido sobre a palheta são apresentados. Determina-se também o campo de geração de entropia para o escoamento bem como sua variação para diversos instantes de tempo.
This work presents the study of unsteady flow in a axially fed radial flow between parallel disks on a situation in which the frontal disk can move. The problem is solved coupling the fluid flow modeling and the valve dynamics movement. The fluid (air) is assumed to have a Newtonian behavior. The flow is incompressible, laminar and isothermal in an axisymmetric geometry. The governing equations are solved by finite volume methodology using a commercial software, FLUENT, which have been modified to admit boundary movement as part of the solution. The flow characteristics presented herein relate to situations where: I. the frontal disk is suddenly moved to a new location and ii. prescribed mass flux at the inlet orifice. Results for the behavior of the axial force in the frontal disk can be seen. Another important parameter analyzed is the entropy generation and its time variation.
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Blagorodnova, Nadejda. "Characterising the Gaia transient sky." Thesis, University of Cambridge, 2016. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.709492.
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Lahlou, Tarek A. (Tarek Aziz). "Parameter recovery for transient signals." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/82406.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2013.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 115-118).
Transient signals naturally arise in numerous disciplines for which the decay rates and amplitudes carry some informational significance. Even when the decay rates are known, solving for the amplitudes results in an ill-conditioned formulation. Transient signals in the presence of noise are further complicated as the signal-to-noise ratio asymptotically decreases in time. In this thesis the Discrete-Time Transient Transform and the Discrete Transient Transform are defined in order to represent a general signal using a linear combination of decaying exponential signals. A common approach to computing a change of basis is to make use of the dual basis. Two algorithms are proposed for generating a dual basis: the first algorithm is specific to a general exponential basis, e.g., real exponential or harmonically related complex exponential bases are special cases of the general exponential basis, while the second algorithm is usable for any general basis. Several properties of a transient domain representation are discussed. Algorithms for computing numerically stable approximate transient spectra are additionally proposed. The inherent infinite bandwidth of a continuous-time transient signal motivates in part the development of a framework for recovering the decay rates and amplitudes of a discrete-time lowpass filtered transient signal. This framework takes advantage of existing parameter modeling, identification, and recovery techniques to determine the decay rates while an alternating projection method utilizing the Discrete Transient Transform determines the amplitudes.
by Tarek A. Lahlou.
S.M.
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Enikolopov, Grigori. "Dispatches from the transient city." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/108836.
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Thesis: M. Arch., Massachusetts Institute of Technology, Department of Architecture, 2017.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis. Page 97 blank.
Includes bibliographical references (page 96).
Unprecedented levels of migration, displacement, and expulsions mark the contemporary moment. With the increase of protracted conflicts and environmental crises, the numbers of displaced persons fleeing war, famine, disease, or poverty has now surpassed levels seen previously only after WWII. As the world urbanizes, rural populations are moving in greater numbers to cities and in the developed world, gentrification reshuffles historical settlement patterns. The spatial technologies that surround this mass movement of persons have been inadequately explored and represented. A new form of urbanism is emerging; not static cities of migration, but conduit cities of populations in motion. This new form of transient urbanism will not replace the static city. Instead it is superimposed upon the existing city, and emerging from its obsolete artifacts. The city of Athens, Greece, a gateway into Europe and confluence on the migrant route from the Middle East, is taken as a case study for architectural speculations into the ways transience alters the experience of cities. Athens poses numerous difficulties and opportunities as the state's ability to formulate meaningful action is challenged by the ongoing government-debt crisis which began in 2009. Another consequence of the crisis has been a hollowing out of the center of the city with vacant building stock increasing into the tens of thousands (Baboulias). This thesis takes the form of a manifesto that aims to replace the camp imaginary with correspondences from the transient city. The proposal projects not a utopian vision of the future but a provisional project already in the process of becoming. Drawing is used as a tool to heighten and amplify the transformations now underway.
by Grigori Enikolopov.
M. Arch.
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Alcock, J. L. "The transient behaviour of condensers'." Thesis, University of Manchester, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.553038.
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Experimental data are presented on the transient behaviour of an industrial scale shelland- tube condenser condensing steam from steam-air mixtures under reduced pressure. Models are developed for the dynamic simulation of a shell-and-tube condenser and for condensation in a single vertical tube. The unsteady behaviour of the UMIST condenser was examined by measuring the response of the system to step changes in the five key operating conditions. These are the pressure, steam load, air load, cooling water flowrate and cooling water inlet temperature. Step increases and decreases in each of these quantities were imposed. The responses of the system pressures, temperatures and flowrates are presented. Conclusions as to the underlying phenomena occurring are put forward. A model of a shell-and-tube condenser was developed within the DIY A dynamic simulation package, Hall et al (1988). This was used to simulate both steady and unsteady experiments using the UMIST condenser. The model was able to predict closely steady-state temperature and pressure profiles. The overall pressure drops with single-phase flow were predicted to within +5% and those with condensation to within ±10%. The simulated responses of the system to the step changes in operating conditions matched closely those seen experimentally. A model of condensation in a single vertical tube was developed within the SPEEDUP dynamic simulation environment, Perkins and Sargent (1982). The system investigated is that of condensation of a single vapour from a non-condensing gas. The condensation process was predicted using the film theory approach. The model was used to simulate the steady-state experimental data of G.Lehr (1972). Good agreement between the experimental and predicted Experimental data are presented on the transient behaviour of an industrial scale shelland- tube condenser condensing steam from steam-air mixtures under reduced pressure. Models are developed for the dynamic simulation of a shell-and-tube condenser and for condensation in a single vertical tube. The unsteady behaviour of the UMIST condenser was examined by measuring the response of the system to step changes in the five key operating conditions. These are the pressure, steam load, air load, cooling water flowrate and cooling water inlet temperature. Step increases and decreases in each of these quantities were imposed. The responses of the system pressures, temperatures and flowrates are presented. Conclusions as to the underlying phenomena occurring are put forward. A model of a shell-and-tube condenser was developed within the DIY A dynamic simulation package, Hall et al (1988). This was used to simulate both steady and unsteady experiments using the UMIST condenser. The model was able to predict closely steady-state temperature and pressure profiles. The overall pressure drops with single-phase flow were predicted to within +5% and those with condensation to within ±10%. The simulated responses of the system to the step changes in operating conditions matched closely those seen experimentally. A model of condensation in a single vertical tube was developed within the SPEEDUP dynamic simulation environment, Perkins and Sargent (1982). The system investigated is that of condensation of a single vapour from a non-condensing gas. The condensation process was predicted using the film theory approach. The model was used to simulate the steady-state experimental data of G.Lehr (1972). Good agreement between the experimental and predicted
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Butler, Christopher R. "Syndrome of transient epileptic amnesia." Thesis, University of Edinburgh, 2009. http://hdl.handle.net/1842/4160.
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Transient epileptic amnesia (TEA) is a form of epilepsy of which the principle manifestation is recurrent, transient episodes of isolated memory loss. Although the phenomenon has been recognised for over a century, it is scantily documented in the medical literature and is often misdiagnosed by clinicians. Recent work has highlighted a number of apparently consistent clinical features among the published cases. However, to date there has been no large, systematic study of the condition. The aim of the work reported in this thesis was to investigate a substantial number of prospectively recruited patients with TEA, and thus be able to provide a detailed and authoritative description of its clinical, neuropsychological and radiological characteristics. Fifty patients with TEA were recruited from around the United Kingdom using established diagnostic criteria, together with a group of matched healthy control subjects. Participants underwent a clinical interview, comprehensive neuropsychological testing and structural magnetic resonance imaging of the brain. The study demonstrated the following features. TEA typically begins in later life. The amnesic episodes are frequent, brief and often occur upon waking. They are characterised by a mixed anterograde and retrograde amnesia, the anterograde component of which is often incomplete. Attacks are commonly associated with olfactory hallucinations. They respond well to anticonvulsant medication. Nevertheless, many patients complain of persistent difficulties with memory. Despite generally performing well on standard tests of anterograde memory, many patients show i) accelerated forgetting of new information over a three-week delay and ii) temporally extensive deficits in autobiographical memory. TEA is associated with subtle medial temporal lobe atrophy on magnetic resonance imaging. This atrophy correlates with performance on standard memory tests, but not with long-term forgetting rates or autobiographical memory deficits. It is proposed that TEA is a distinctive syndrome of epilepsy, typically misdiagnosed at presentation, caused by medial temporal seizure activity and associated with accelerated long-term forgetting and autobiographical memory loss. These unusual forms of memory impairment have been documented in other forms of epilepsy. They pose challenges to current models of memory. The syndrome of TEA is therefore both clinically and theoretically important.
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Hageman, Stephen James. "Complex Attosecond Transient-absorption Spectroscopy." The Ohio State University, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=osu1608050018545904.
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O'Meara, N. "Size discrimination of transient signals." Thesis, University of Southampton, 2012. https://eprints.soton.ac.uk/349078/.
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The importance of spectral cues in size discrimination of transient signals was investigated, and a model for this ability, tAIM, was created based on the biological principles of human hearing. A psychophysics experiment involving 40 participants found that the most important cue for size discrimination of transient signals, created by striking different sizes of polystyrene spheres, was similar to that of speakers listening to vowels – the relative positions of the resonances between comparison signals. It was found possible to scale the sphere signals in order to confuse listeners into believing the signal source was a different size, but two methods of scaling signals in order to sound the same size as another proved inconclusive, suggesting the possibility that transient signals cannot be scaled in a linear fashion as has been shown possible for vowels. Filtering the signals in a number of different ways found that the most important cue in size discrimination of transient signals is the difference between the most prominent resonances available in the spectra of the comparison signals. A model of the auditory system using the dynamic compressive Gammachirp filterbank, and based on the well-known AIM, was created to produce auditory images of transient signals that could be normalised for size. Transient-AIM, or tAIM used the Mellin transform to produce images that showed size normalisation was possible due to the spectral envelope similarities across the sizes of the spheres. tAIM was extended to carry out size discrimination of the spheres using the information contained within the Mellin images. There was a systematic association between Mellin phase and size of objects of various shapes, which suggests that tAIM is able to infer object size from sound recordings of objects being struck.
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Khan, Md Nazmus Shakib. "Transient Voltage Distribution in Bushing." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-292753.
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An electrical bushing is one of the most important elements in a power transformer. Steep front surges such as transient impulse voltage from lightning strikes is an inevitable electromagnetic transient mostly happening in power transmission and distribution system. The bushing might lead to be degraded due to such kind of surge. This project deals with overvoltage stress distribution on the transformer bushing under the effect of electromagnetic transient response such as lightning impulse. To understand the behavior of transient response on the bushing, a proper model of power transformer bushing is built-in Comsol multiphysics to authenticate the stress distribution. The electromagnetic wave of impulse propagates onto the overhead line that connects with the transformer. Some understanding of the transient behavior of a conductor bushing has been achieved through studying the influence of inductance property and the skin effect characteristics of a multi-layer coaxial cable on the wave propagation, which has been structured in this project to simplify the model. On the other hand, the skin effect analysis on the conductor of the bushing has been taken also into account in this project using real conductor simulation in the Comsol model. Thus, it will be interesting to compare the real conductor model with the perfect conductor of the bushing through analyzing the current density effect on it. In this project, multi-layer of coaxial cable and transformer bushing are simulated. The simulation is carried out for time domain and frequency domain in Comsol based on the model characteristics.En elektrisk genomföring är ett av de viktigaste elementen i en transformator. Spänningsvågor med branta fronter som impulsspänningar från blixtnedslag är ett oundvikligt elektromagnetiskt övergående fenomen som oftast sker i kraftöverförings- och distributionssystem. Genomföringen kan leda till att degraderas på grund av en sådan våg. Detta projekt handlar om fördelning av överspännings på transformatorgenomföringen under påverkan av elektromagnetisk transient respons, såsom blixtimpuls. För att förstå beteendet hos övergående respons på genomföringen är en korrekt modell av transformatorgenomföring inbyggd Comsol-flerfysik för att autentisera spänningsfördelningen. Den elektromagnetiska impulsvågen fortplantas från luftledningen som ansluter till transformatorn. Viss förståelse för det övergående beteendet hos en ledargenomföring har uppnåtts genom att studera påverkan av induktansegenskaper och hudeffektegenskaperna hos en flerskikts koaxialkabel på vågutbredningen, vilket har strukturerats i detta projekt för att förenkla modellen. Å andra sidan har hudeffektanalysen på genomföringens ledare beaktats i detta projekt med användning av verklig ledarsimulering i Comsol-modellen. Således blir det intressant att jämföra den riktiga ledarmodellen med den perfekta ledaren för genomföringen genom att analysera strömtäthetseffekten på den. I detta projekt simuleras flerskikt av koaxialkabel och transformatorgenomföring. Simuleringen utförs för tidsdomän och frekvensdomän i Comsol baserat på modellegenskaperna.
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Sirvole, Kishore. "Transient Analysis in Pipe Networks." Thesis, Virginia Tech, 2007. http://hdl.handle.net/10919/31444.
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Power failure of pumps, sudden valve actions, and the operation of automatic control systems are all capable of generating high pressure waves in domestic water supply systems. These transient conditions resulting in high pressures can cause pipe failures by damaging valves and fittings. In this study, basic equations for solving transient analysis problems are derived using method of characteristics. Two example problems are presented. One, a single pipe system which is solved by developing an excel spreadsheet. Second, a pipe network problem is solved using transient analysis program called TRANSNET.
A transient analysis program is developed in Java. This program can handle suddenly-closing valves, gradually-closing valves, pump power failures and sudden demand changes at junctions. A maximum of four pipes can be present at a junction. A pipe network problem is solved using this java program and the results were found to be similar to that obtained from TRANSNET program. The code can be further extended, for example by developing java applets and graphical user interphase to make it more user friendly.
A two dimensional (2D) numerical model is developed using MATLAB to analyze gaseous cavitation in a single pipe system. The model is based on mathematical formulations proposed by Cannizzaro and Pezzinga (2005) and Pezzinga (2003). The model considers gaseous cavitation due to both thermic exhange between gas bubbles and surrounding liquid and during the process of gas release. The results from the model show that during transients, there is significant increase in fluid temperature along with high pressures. In literature pipe failures and noise problems in premise plumbing are atributed to gaseous cavitation.
Master of Science
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Yang, Min-Chieh. "Electronic spectroscopy of transient molecules /." The Ohio State University, 1998. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487949508372826.
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Wright, Darryl Edmund. "Machine learning for transient surveys." Thesis, Queen's University Belfast, 2016. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.709863.
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Efficient identification and follow-up of astronomical transients is hindered by the need for humans to manually select promising candidates from data streams that contain many false positives and prioritise those candidates for follow-up. These difficulties are faced by most ground-based time domain surveys. This dependence on humans is unsustainable for next generation all-sky surveys and significant effort is now being invested to solve the problem computationally. In this work we investigate machine learning approaches to difference image artefact rejection and contextual classification of transient discoveries. We construct training sets from data gathered during the course of Pan-STARRS1 survey operations. In all cases the feature representation is carefully selected such that it is independent of the specific Pan-STARRS1 image processing pipeline and survey strategy, with the aim of designing solutions that can be easily applied to other current and future transient searches. We explore a number of machine learning algorithms and carefully evaluate their performance on these tasks. This thesis has developed working code that is now applied on the live PS1 data stream on a nightly basis. This acts as a useful testbed for application to future surveys such as LSST.
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Mao, Xuerui. "Vortex instability and transient growth." Thesis, Imperial College London, 2010. http://hdl.handle.net/10044/1/6442.
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The dynamics of vortex flow is studied theoretically and numerically. Starting from a local analysis, where the perturbation in the vortex flow is Fourier decomposed in both radial and azimuthal directions, a modified Chebyshev polynomial method is used to discretize the linearized governing operator. The spectrum of the operator is divided into three groups: discrete spectrum, free-stream spectrum and potential spectrum. The first can be unstable while the latter two are always stable but highly non-normal. The non-normality of the spectra is quantitatively investigated by calculating the transient growth via singular value decomposition of the operator. It is observed that there is significant transient energy growth induced by the non-normality of continuous spectra. The non-normality study is then extended to a global analysis, in which the perturbation is decomposed in the radial or azimuthal direction. The governing equations are discretized through a spectral/hp element method and the maximum energy growth is calculated via an Arnoldi method. In the azimuthally-decomposed case, the development of the optimal perturbation drives the vortex to vibrate while in the stream-wise-decomposed case, the transient effects induce a string of bubbles along the axis of the vortex. A further transient growth study is conducted in the context of a co-rotating vortex pair. It is noted that the development of optimal perturbations accelerates the vortex merging process. Finally, the transient growth study is extended to a sensitivity analysis of the vortex flow to inflow perturbations. An augmented Lagrangian function is built to optimize the inflow perturbations which maximize the energy inside the domain over a fixed time interval.