Rozprawy doktorskie na temat „Time-varying flow”
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Raben, Samuel Gillooly. "Determination of Three Dimensional Time Varying Flow Structures". Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/51818.
Pełny tekst źródłaPh. D.
Chen, Chun-Ming. "Data Summarization for Large Time-varying Flow Visualization and Analysis". The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1469141137.
Pełny tekst źródłaFestger, Adam Douglas. "Analysis of hydraulic capture zones and efficiency under time-varying flow and pumping conditions". Thesis, The University of Arizona, 2000. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_e9791_2000_30_sip1_w.pdf&type=application/pdf.
Pełny tekst źródłavan, Mierlo Tim, i Rafal Żywalewski. "Evaluation of time varying stresses in a Howden fan". Thesis, Linnéuniversitetet, Institutionen för maskinteknik (MT), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-43752.
Pełny tekst źródłaZigic, Sasha, i n/a. "A Methodology to Calculate the Time-Varying Flow Through a Hydraulic Structure Connecting Two Water Bodies". Griffith University. School of Engineering, 2005. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20060111.145655.
Pełny tekst źródłaZigic, Sasha. "A Methodology to Calculate the Time-Varying Flow Through a Hydraulic Structure Connecting Two Water Bodies". Thesis, Griffith University, 2005. http://hdl.handle.net/10072/365304.
Pełny tekst źródłaThesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Engineering
Full Text
QUET, Pierre-Francois D. "A ROBUST CONTROL THEORETIC APPROACH TO FLOW CONTROLLER DESIGNS FOR CONGESTION CONTROL IN COMMUNICATION NETWORKS". The Ohio State University, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=osu1032194223.
Pełny tekst źródłaKim, Minseok, Luke A. Pangle, Charléne Cardoso, Marco Lora, Till H. M. Volkmann, Yadi Wang, Ciaran J. Harman i Peter A. Troch. "Transit time distributions and StorAge Selection functions in a sloping soil lysimeter with time-varying flow paths: Direct observation of internal and external transport variability". AMER GEOPHYSICAL UNION, 2016. http://hdl.handle.net/10150/622147.
Pełny tekst źródłaLee, Teng-Yok. "Data Triage and Visual Analytics for Scientific Visualization". The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1321889683.
Pełny tekst źródłaZhang, Caixia. "Advanced volume rendering". Columbus, Ohio : Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1143150322.
Pełny tekst źródłaTong, Xin. "Interactive Visual Clutter Management in Scientific Visualization". The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1471612150.
Pełny tekst źródłaResvanis, Themistocles L. "Vortex-induced vibration of flexible cylinders in time-varying flows". Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/93782.
Pełny tekst źródłaThis 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.
Includes bibliographical references (pages 221-226).
This thesis investigates two aspects of Vortex-Induced Vibrations (VIV) on long flexible cylinders. The work is split into a minor and major part. The minor part addresses the effect of Reynolds number on flexible cylinder VIV. The major contribution addresses the prediction of VIV under unsteady current excitation or time-varying flows. The study on the effect of Reynolds number makes extensive use of a recent set of experiments performed by MARINTEK on behalf of SHELL Exploration and Production Co. Three 38[gamma] long cylinders of different diameters were towed through the ocean basin over a wide range of Reynolds numbers in both uniform and sheared flows. The experimental data showed that the response amplitudes and dimensionless response frequency are strongly influenced by the Reynolds number. Both of these Reynolds effects should be of interest to riser designers that traditionally rely on experimental data obtained at much lower Reynolds numbers. In this thesis, I propose a dimensionless parameter, [gamma], that governs whether lock-in under unsteady flow conditions is possible and show that it is useful for determining a priori whether the response under unsteady conditions will be similar to the response under steady flows. The unsteady flow parameter, [gamma], describes the change in flow speed per cycle of cylinder vibration and is defined as: ... The experimental data necessary to support this work is taken from a set of experiments performed at the State Key Laboratory of Ocean Engineering at Shanghai Jiao Tong University (SJTU), where a 4[gamma] long flexible cylinder was towed through an ocean basin under carefully selected amounts of acceleration/deceleration. Analysis of the experimental data showed that the response can typically be divided into three regimes based on the [gamma] value: For very quickly accelerating flows ([gamma] > 0.1) the cylinder cannot react quickly enough and at most a couple of cycles of small amplitude vibration will be observed. For moderately accelerating flows (0.02 < [gamma] < 0.1), the cylinder will typically start vibrating and can build up a significant response. However, most of the time, the flow will have exited the required synchronization region before the cylinder manages to reach the large amplitudes observed in steady flows. For very slowly accelerating flows ([gamma] < 0.02), the flow is changing considerably slower than the cylinder's reaction time and thus, the cylinder has more than enough time to build up its response. Under these conditions, the observed response is qualitatively similar to the response of flexible cylinders in steady flows. The [gamma] dependence that was identified in the SJTU data is not limited to that specific situation but instead, is a general property of low mass ratio cylinders vibrating in unsteady flows. This is shown by demonstrating how the unsteady flow parameter, [gamma], can be used to analyze unsteady response data from the aforementioned SHELL tests where the riser models were considerably longer than the SJTU model. This thesis shows how a single ramp test -- where the towing speed is continuously varied in a control manner -- may be used to obtain the same information as 10 constant speed tests covering the range of speeds. This can and will significantly reduce the number of runs necessary to completely characterize the VIV response of flexible cylinders and will translate into large cost savings in the future. The thesis closes by describing the differences observed in the VIV response at high mode numbers depending on whether the time-varying flow was accelerating or decelerating. In both situations a 'hysteresis' effect is noted, where the cylinder is found to 'lag behind' preferring to vibrate in the previously excited mode as a result of cylinder lock-in. In accelerating flows, this means that the cylinder will typically be responding one mode lower than it would have in a steady flow. In decelerating flows, the same 'lag' or 'hysteresis' will cause the cylinder to respond one (or more) mode number(s) higher than it would have in a steady flow.
by Themistocles L. Resvanis.
Ph. D.
Opasanon, Sathaporn. "On finding paths and flows in multicriteria, stochastic and time-varying networks". College Park, Md. : University of Maryland, 2004. http://hdl.handle.net/1903/2067.
Pełny tekst źródłaThesis research directed by: Civil Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
Saadi, Yusron. "The influence of different time varying antecedent flows on the stability of mixed grain size deposits". Thesis, University of Sheffield, 2002. http://etheses.whiterose.ac.uk/12833/.
Pełny tekst źródłaRohmer, Jérémy. "Importance ranking of parameter uncertainties in geo-hazard assessments". Thesis, Université de Lorraine, 2015. http://www.theses.fr/2015LORR0237/document.
Pełny tekst źródłaImportance ranking of parameter uncertainties in geo-hazard assessments Epistemic uncertainty can be reduced via additional lab or in site measurements or additional numerical simulations. We focused here on parameter uncertainty: this corresponds to the incomplete knowledge of the correct setting of the input parameters (like values of soil properties) of the model supporting the geo-hazard assessment. A possible option tomanage it is via sensitivity analysis, which aims at identifying the contribution (i.e. the importance) of the different input parameters in the uncertainty on the final hazard outcome. For this purpose, advanced techniques exist, namely variance-basedglobal sensitivity analysis. Yet, their practical implementation faces three major limitations related to the specificities of the geo-hazard domain: 1. the large computation time cost (several hours if not days) of numerical models; 2. the parameters are complex functions of time and space; 3. data are often scarce, limited if not vague. In the present PhD thesis, statistical approaches were developed, tested and adapted to overcome those limits. A special attention was paid to test the feasibility of those statistical tools by confronting them to real cases (natural hazards related to earthquakes, cavities and landslides)
Tsai, Wen-Bin, i 蔡文彬. "Convergence Acceleration by Varying Time Stepsize for Turbulent Flow Computation". Thesis, 2000. http://ndltd.ncl.edu.tw/handle/01600736056127139162.
Pełny tekst źródła國立清華大學
數學系
88
In this study, numerical computations by simple SIMPLE (LBL), PISO (LBL+PISO), pre-conditioned Bi-CGSTAB on SIMPLE, and pre-conditioned Bi-CGSTAB on PISO are computed for some problems to demonstrate the effectiveness of the algorithm pre-conditioned Bi-CGSTAB on SIMPLE. This method is also applied to evaluate the heat transfer and fluid flow behavior in a rectangular channel with streamwise-periodic ribs mounted on one of the principal wall. The numerical results show that all the models tested can predict the flowfield reasonable well, and the inclusion of Yap term in the equation (or equation) can further improve the prediction of heat transfer coefficient in these models, model and model. Furthermore, a design of varying step size concept both in time span and spatial coordinate systems to achieve fast convergence is also demonstrated. The determination of the step size based on the concept of minimization of residuals by the Bi-CGSTAB algorithm is proposed. The numerical results show that the time stepsize adjustment based on the Bi-CGSTAB method improves the convergence rate for turbulent computations using advanced turbulence models in low-Reynolds number forms, and the degree of improvement increases with the degree of complexity of the turbulence models.
Pu, Jaan H., Songdong Shao i Y. Huang. "Shallow sediment transport flow computation using time-varying sediment adaptation length". 2014. http://hdl.handle.net/10454/8342.
Pełny tekst źródłaBased on the common approach, the adaptation length in sediment transport is normally estimated in the temporal independence. However, this approach might not be theoretically justified as the process of reaching of the sediment transport equilibrium stage is affected by the flow conditions in time, especially for those fast sediment moving flows, such as scour-hole developing flow. In this study, the 2D shallow water formulation together with a sediment continuity-concentration (SCC) model were applied to flow with mobile sediment boundary. A time-varying approach was proposed to determine the sediment transport adaptation length to treat the flow sediment erosion-deposition rate. The proposed computational model was based on the Finite Volume (FV) method. The Monotone Upwind Scheme of Conservative Laws (MUSCL)-Hancock scheme was used with the Harten Lax van Leer-contact (HLLC) approximate Riemann solver to discretize the FV model. In the flow applications of this paper, a highly discontinuous dam-break fast sediment transport flow was used to calibrate the proposed time-varying sediment adaptation length model. Then the calibrated model was further applied to two separate experimental sediment transport flow applications documented in literature, i.e. a highly concentrated sediment transport flow in a wide alluvial channel and a sediment aggradation flow. Good agreements with the experimental data were presented by the proposed model simulations. The tests prove that the proposed model, which was calibrated by the discontinuous dam-break bed scouring flow, also performed well to represent the rapid bed change and the steady sediment mobility conditions.
The National Natural Science Foundation of China NSFC (Grant Number 20101311246), Major State Basic Research Development Program (973 program) of China (Grant Number 2013CB036402) and Open Fund of the State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University of China (Grant Number SKLH-OF-1103).
Robinson, Joshua Westly. "Modeling Time-Varying Networks with Applications to Neural Flow and Genetic Regulation". Diss., 2010. http://hdl.handle.net/10161/3109.
Pełny tekst źródłaMany biological processes are effectively modeled as networks, but a frequent assumption is that these networks do not change during data collection. However, that assumption does not hold for many phenomena, such as neural growth during learning or changes in genetic regulation during cell differentiation. Approaches are needed that explicitly model networks as they change in time and that characterize the nature of those changes.
In this work, we develop a new class of graphical models in which the conditional dependence structure of the underlying data-generation process is permitted to change over time. We first present the model, explain how to derive it from Bayesian networks, and develop an efficient MCMC sampling algorithm that easily generalizes under varying levels of uncertainty about the data generation process. We then characterize the nature of evolving networks in several biological datasets.
We initially focus on learning how neural information flow networks change in songbirds with implanted electrodes. We characterize how they change in response to different sound stimuli and during the process of habituation. We continue to explore the neurobiology of songbirds by identifying changes in neural information flow in another habituation experiment using fMRI data. Finally, we briefly examine evolving genetic regulatory networks involved in Drosophila muscle differentiation during development.
We conclude by suggesting new experimental directions and statistical extensions to the model for predicting novel neural flow results.
Dissertation
Ashford, Graeme. "A Time-varying Feedback Approach to Reach Control on a Simplex". Thesis, 2011. http://hdl.handle.net/1807/30167.
Pełny tekst źródłaHo, Chen Yi, i 何建毅. "Stability Analysis and Vibration Control of Pipes Conveying Fluid with Time-varying Flow Speeds". Thesis, 1998. http://ndltd.ncl.edu.tw/handle/22865124581238757295.
Pełny tekst źródła國立海洋大學
機械與輪機工程學系
86
Dynamic analysis and control of pipes conveying time- varyingfluid is examined in this work. A finite element model is developedfor the moving fluid. For stability analysis, a finite element modelwhich includes the effects of shearing deformations and rotary inertia, know as Timoshenko beam theory, is applied. The force due to the axial accleration is include for analysis. The stability condition, defined by the flow variation frequency and the variation amplitude, are determined by using the Bolotin's method. The procedure isdifferent from the pronlem with a constant flow speed where the stabilitycan be analyzed by using the root locus plot. The size and position of the stability region are dependent of the system parameters. Ina numberical example, good agreement is observed between the analysisresults of this work and those of the literature for slender pipes.the dependence of the stability region and system parameters, shchas mean flow speed, mass ratio, slenderness ratio, is examined in thiswork. A direct feedback control approach is applied to investigatethe stability properties of pipes conveying time-varying fluid. Thesize and position of the stability region are examined by using anactuator with velocity and/or displacement feedback. The effect ofactuator position on stability of the system is analyzed. The ModelReference Adaptive Control(MRAC) approach is also applied for activevibration control suppression of the pipe system. For pipes conveyingtime- varying fluid, flutter may occur even when the flow speed is below the critical one as for a constant flow speed problem. The MRACis applied in this study to supress flutter. It is shown the approachis robust for a system with variations, unknown to the control system,of mean velocity, amplitude, and frequency. The control system can stillbe operational without changing the control parameters for a system withparameter uncertainties. A numberical example is given to demonstratethe robustness of the MRAC approach for vibration suppression of pipesconveying time- varying fluid with the mean flow speed below the criticalone.
Bella, David Wayne. "Flow visualization of time-varying structural characteristics of Dean vortices in a curved channel". Thesis, 1988. http://hdl.handle.net/10945/23236.
Pełny tekst źródłaThe time varying development and structure of Dean vortices were studies using flow visualization. Observations were made over a range of Dean numbers from 40 to 200 using a transparent channel with mild curvature, 40:1 aspect ratio, and an inner to outer radius ratio of 0.979. Seven flow visualization techniques were tried but only one, a wood burning smoke generator, produced usable results. Different vortex characteristics were observed and documented in sequences of photographs space one quarter of a second apart at locations ranging from 85 to 135 degrees from the start of curvature. Evidence is presented that supports the twisting/rocking nature of the flow.
http://archive.org/details/flowvisualizatio00bell
Lieutenant, United States Navy
Fang, Hui. "Vector field manipulations in 3-D time-varying flow data compression and image/video editing /". 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3223587.
Pełny tekst źródłaSource: Dissertation Abstracts International, Volume: 67-07, Section: B, page: 3893. Adviser: John C. Hart. Includes bibliographical references (leaves 101-104) Available on microfilm from Pro Quest Information and Learning.
Chen, Rex Chin-Hao, i 陳勁豪. "High-speed laser speckle contrast imaging of in-vivo cerebral blood flow time varying events". Thesis, 2015. http://ndltd.ncl.edu.tw/handle/34123055252752786874.
Pełny tekst źródła中原大學
電子工程研究所
103
Laser Speckle Contrast Imaging (LSCI) is a non-scanning wide field-of-view optical imaging technique specifically developed for cerebral blood flow monitoring. In this project a versatile Laser speckle contrast imaging system has been proposed to monitor hemodynamics changes in functional activation experiment and pulsatile blood flow to examine the vasculature physical properties. The hardware of the system consists of a high speed CMOS camera, a coherent source, a Trinocular microscope, and a PC that does camera controlling and data storage. The simplicity of its hardware system is suitable for biological experiments. Under experimental setting, the proposed system shows a linear relationship between the blood flow index (ICT) and controlled flow rate of the microchannel. This linear relationship has a minimum coefficient of determination〖 r〗^2= 0.96 with camera exposure time setting of 75μs. This permitted LSCI can be used in the enhanced sample rate setting and allow sample rate up to 13000 Hz which will be bounded by camera capacity. The proposed LSCI system has applied in two experiments of functional activation in rat, a 12 % hypoxia event and a Phenylephrine injection event. The 12% hypoxia results show blood flow time trace produced from proposed system shows positive correlation with the aortic pulse wave velocity. The Phenylephrine injection results show the hemodynamic response measured from proposed LSCI correlate well with the results found in the literature. To exemplify the instantaneous pulsatility flow study acquired with high sample rate, a pulsatile cerebral blood flow analysis has been conducted on two vessels, an arteriole and a venule. The pulsatile waveform results captured under 1869Hz sample rate shows there is no phase delay between the foot of the pulsatile flow of the arteriole and the venule. The pulse of the arteriole rise 13ms faster than the pulse of the venule, and it takes 6ms longer for the pulse of the arteriole to fall below the lower fall-time boundary. By using second order derivative (accelerated) blood flow index the vascular stiffness can be evaluated, the results shows the arteriole and the venule have increased vascular stiffness index (b/a amplitude ratio) of 0.95 and 0.74. On the other side, the arteriole and the venule have the decreased vascular stiffness index (c/a amplitude ratio) of 0.125 and 0.35. Both accelerated blood blow index suggested the arteriole has higher stiffness than the venule. The proposed LSCI system can monitor not only the mean blood flow over function activation experiment but also pulsatile flow which provided vascular stiffness metrics for estimating the stroke preliminary symptom and may provide insight of the casualness of the stroke and support the development of instantaneous cure to minimize the damage to the brain.
Nasrabadi, Ebrahim [Verfasser]. "Dynamic flows in time-varying networks / vorgelegt von Ebrahim Nasrabadi". 2009. http://d-nb.info/995962839/34.
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