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Shaw, Ryan Phillip. "Application of Subjective Logic to Vortex Core Line Extraction and Tracking from Unsteady Computational Fluid Dynamics Simulations." BYU ScholarsArchive, 2012. https://scholarsarchive.byu.edu/etd/2989.
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Presented here is a novel tool to extract and track believable vortex core lines from unsteady Computational Fluid Dynamics data sets using multiple feature extraction algorithms. Existing work explored the possibility of extracting features concurrent with a running simulation using intelligent software agents, combining multiple algorithms' capabilities using subjective logic. This work modifies the steady-state approach to work with unsteady fluid dynamics and is designed to work within the Concurrent Agent-enabled Feature Extraction concept. Each agent's belief tuple is quantified using a predefined set of information. The information and functions necessary to set each component in each agent's belief tuple is given along with an explanation of the methods for setting the components. This method is applied to the analyses of flow in a lid-driven cavity and flow around a cylinder, which highlight strengths and weaknesses of the chosen algorithms and the potential for subjective logic to aid in understanding the resulting features. Feature tracking is successfully applied and is observed to have a significant impact on the opinion of the vortex core lines. In the lid-driven cavity data set, unsteady feature extraction modifications are shown to impact feature extraction results with moving vortex core lines. The Sujudi-Haimes algorithm is shown to be more believable when extracting the main vortex core lines of the cavity simulation while the Roth-Peikert algorithm succeeding in extracting the weaker vortex cores in the same simulation. Mesh type and time step is shown to have a significant effect on the method. In the curved wake of the cylinder data set, the Roth-Peikert algorithm more reliably detects vortex core lines which exist for a significant amount of time. the method was finally applied to a massive wind turbine simulation, where the importance of performing feature extraction in parallel is shown. The use of multiple extraction algorithms with subjective logic and feature tracking helps determine the expected probability that an extracted vortex core is believable. This approach may be applied to massive data sets which will greatly reduce analysis time and data size and will aid in a greater understanding of complex fluid flows.
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DAGAN, ARIE. "SOME ASPECTS OF VORTEX LINE RECONNECTION." Diss., The University of Arizona, 1986. http://hdl.handle.net/10150/188144.
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Turbulence has long been believed to be associated with the behavior of vorticity. Ever since experiments showed clearly the presence of vortex structures in turbulent flow, concentrated efforts have tried to identify the important dynamics of three-dimensional vortex flow. In particular, conjectures abound about the importance of vortex stretching and vortex line reconnection. Numerical experiments based on ad hoc assumptions on the nature of the cores of vortex filaments have shown interesting behavior. In some cases, it has been argued that singularities develop in finite time and in other cases that the filament exhibits fractal dimensions. These inviscid calculations also show that filaments of opposite signed vorticity tend to pair up and that the local flow is two-dimensional. Consequently, we have begun a study that clarifies the behavior of a pair of counter-rotating vortices in the presence of an external strain flow that would be induced by the presence of vorticity well away from the local two-dimensional plane. So far, the results are quite interesting and depend on the nature of the strain flow. We always assume that the horizontal component of the strain pushes the filaments together. It is the other two components that then affect the results. Without any strain along the axes of the filaments, the vortex cores are pulled into parallel elliptical shapes. Eventually, the cores are so deformed that they become unstable in the same way a parallel shear flow would and the vortex structures disrupt. This phenomenon will be missed by filament codes that assume the cores remain circular. On the other hand, a strain component along the filaments increases the vorticity but keeps the core structure mostly circular. As the cores approach one another, viscous effects overcome the increase in vorticity due to stretching and the cores dissipate away.
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Lin, Fung-Yaw. "Core-line tracing of digital images of line drawings." Thesis, Cranfield University, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.302773.
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Edblom, Christin. "Numerical Studies of Vortex Core States in Type II Superconductors." Thesis, Umeå universitet, Institutionen för fysik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-55159.
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In this thesis, we study an isolated vortex in an s-wave superconductor by solving the Bogoliubov-de Gennes equations self-consistently on a disc. We calculate the order parameter and supercurrent profiles, as well as the distribution of quasiparticle states. In contrast to quasi-classical treatments, the ratio Δ∞/EF between the order parameter and the Fermi energy is not assumed negligible. We study a regime where this ratio is on the order of 10-1, relevant to high-temperature superconductors. In this regime, we find a Friedel-like oscillation in the order parameter profile at low temperatures. This oscillation is attributed to an increased level spacing of the quasiparticle states, causing a decrease of the number of states present inside the superconducting energy gap. The results are in good agreement with previously published works. In future studies, the method used in this thesis will be generalized to d-wave superconductors.<br>I detta examensarbete studeras en ensam virvel i en s-vågssupraledare genom att självkonsistent lösa Bogoliubov och de Gennes' ekvationer på en cylinderskiva. Vi beräknar ordningsparameter- och superströmsprofiler, samt fördelningen av kvasipartikeltillstånd. Till skillnad från i kvasiklassiska metoder så antas inte kvoten Δ∞/EF mellan ordningsparametern och Fermi-energin vara negligerbar. Vi studerar en regim där denna kvot är av storleksordningen 10-1, vilket är fallet i högtemperatur-supraledare. Vid låga temperaturer finner vi i denna regim en Friedelliknande oscillation i ordningsparameterprofilen. Denna oscillations förklaras genom att separationen mellan kvasipartikeltillstånd ökar, vilket får som effekt att färre tillstånd ryms innanför det supraledande energigapet. Våra resultat överensstämmer väl med tidigare publicerade artikler. I framtida studier kommer metoden vi använder i detta examensarbete att generaliseras till d-vågssupraledare.
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Persson, Milton. "Transient Dynamics and Core Tunneling in Vertical Spin-Vortex Pairs." Thesis, KTH, Tillämpad fysik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-244049.
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Persson, Milton. "Transient Dynamics and Core Tunneling in Vertical Spin-Vortex Pairs." Thesis, KTH, Nanostrukturfysik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-242225.
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Spin-vortices in vertically spaced pairs of thin elliptical Permalloy nanoparticles are investigated. The two vortex cores with parallel out-of-plane magnetization exhibit a strong monopole-like attraction through the spacer much thinner than the core length, thus forming a bound core-core pair. The material of the spacer is designed to suppress both direct and indirect exchange interactions, so the remaining inter-vortex coupling is purely dipolar. In the investigated vortex pairs, the in-plane magnetization in the vortex periphery, outside the vortex cores, curl in opposite directions (have opposite chirality). As a result, the two cores move in opposite directions in response to an in-plane magnetic field, the Zeeman effect of which acts to decouple the core-core pair. This leads to unique dynamics of the spin-vortex parallel-core/antiparallel-chirality pair, which strongly depend on whether the pair is coupled or decoupled. In the coupled state, the cores are held close together by the core-core attraction, which results in short-radius oscillations and a resonance frequency of about 2 GHz for the main rotational eigen-mode. In the decoupled state, the cores are separated by a distance much greater than the core length and gyrate independently with a resonance frequency of the order of 100 MHz. The dynamics of the vortex pair are investigated at 77 K, where there is a bistability between the coupled and decoupled core states. Resonant excitations are used to decouple the cores with pulses of ∼10 Oe in amplitude and ∼100 ps in duration. The ability to decouple a vortex pair using such fast low-power pulses can be useful for multifrequency oscillators and vortex based memory. A search for quantum effects is undertaken at sub-Kelvin temperatures using a dilution refrigerator. Square pulses of 100 ns duration and amplitudes of the order of 1 Oe are applied in-plane to bring the system closer to decoupling, giving the cores a chance to tunnel through the barrier between the coupled and decoupled states. The amplitude required for decoupling is measured as a function of temperature and a leveling off in the decoupling probability is seen below 400 mK, giving some indication of core tunneling. Macroscopic quantum tunneling of magnetization is interesting from the fundamental physics point of view, e.g., as a model system for studying the measurement paradox in quantum mechanics, as well as for current and future computer technology in terms of understanding the ultimate limitations of miniaturizing magnetic memory elements.<br>I detta arbete studeras spinnvirvlar i elliptiska skivor av Permalloy ordnade i vertikala par. Kärnor av parallell vertikal magnetisering attraherar varandra likt monopoler genom en film mycket tunnare än kärnorna och bildar därmed ett sammankopplat par. Materialet i filmen mellan virvlarna är designat för att förhindra både direkt och indirekt utbytesväxelverkan och lämnar endast kärnornas dipolväxelverkan. I de virvelpar som studeras går den plana magnetiseringen i virvlarnas periferi runt kärnorna åt olika håll (de har motsatt kiralitet). På grund av detta rör sig kärnorna åt olika håll vid applikation av magnetfält i planet (Zeeman effekten) vilket kan leda till att de kopplas isär. Detta ger virvelpar med parallella kärnor och antiparallell kiralitet unika dynamiska egenskaper som ändras med deras tillstånd, sammankopplade eller isärkopplade. I det sammankopplade tillståndet hålls kärnorna ihop av monopolattraktionen vilket gör att de bara kan röra sig i små banor kring sitt magnetiska masscentrum, med en resonansfrekvens på circa 2 GHz. I det isärkopplade tillståndet är kärnorna separerade med ett avstånd som är mycket större än kärnornas diameter, och de rör sig oberoende av varandra med en resonansfrekvens i storleksordningen 100 MHz. Virvelparets dynamik undersöks vid 77 K, där det finns en bistabilitet mellan det sammankopplade och det isärkopplade tillståndet. Pulser med längd ∼100 ps och styrka ∼10 Oe i resonans med det sammankopplade tillståndet används för att koppla isär kärnorna. Att kunna koppla isär dem med så korta lågeffektspulser kan vara användbart för virvelbaserade minnen och multifrekvensoscillatorer. Ett sökande efter kvanteffekter påbörjas vid temperaturer under 1 K med hjälp av en utspädningskyl. Fyrkantsvågor med en längd på 100 ns och en styrka i storleksordningen 1 Oe, orienterade i planet, används för att ge kärnorna en chans att tunnla genom barriären mellan det sammankopplade och det isärkopplade tillståndet. Den vågamplitud som krävs för att koppla isär kärnorna plottas mot temperaturen och kan ses plana ut under 400 mK, vilket ger viss indikation av tunnling. Dessa undersökningar av makroskopisk kvanttunnling av magnetisering kan vara användbar i grundforskning för att studera mätparadoxen i kvantmekanik, men också i modern datorteknologi för att förstå de absoluta begränsningarna i hur små magnetiska minneselement kan göras.
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Griswold, Donald L. "Dynamics of the vortex line density in superfluid turbulence /." The Ohio State University, 1986. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487267024995376.
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Aronsen, Kristoffer Høyem. "An Experimental Investigation of In-line and Combined In-line and Cross-flow Vortex Induced Vibrations." Doctoral thesis, Norwegian University of Science and Technology, Department of Marine Technology, 2007. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-1894.
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<p>This thesis presents results from an experimental investigation of hydrodynamic forces on a cylinder under prescribed harmonic motions in uniform flow. The purpose of the experiments has been to find hydrodynamic coefficients for pure in-line (IL) oscillations and investigate the interaction between IL and cross-flow (CF) vortex induced vibrations (VIV). Hydrodynamic forces are hence measured in both directions.</p><p>The experiments are performed in a towing tank of 40m, using a rigid cylinder of aspect ratio 20. The cylinder is installed in a yoke structure which in turn is suspended to an overhanging tow carriage. Model oscillations are achieved by oscillating the yoke on the carriage, while the flow velocity is obtained by moving the carriage at constant speed in still water. All experiments are performed at Reynolds number 2.4•10<sup>4</sup>. Three main types of experiments are carried out:</p><p>1. IL oscillations where the frequencies and amplitudes are varied to obtain a detailed map of the forces acting on a cylinder in the pure IL VIV regime.</p><p>2. Two degree-of-freedom motions resembling the oscillation patterns observed in a flexible beam experiment.</p><p>3. Two degree-of-freedom motion tests where the shape and direction of the orbital paths are systematically varied.</p><p>From the detailed knowledge of the excitation forces in the pure IL VIV regime, obtained in the first set of experiments, a novel approach for determining the effect of structural damping is introduced. This approach makes it possible to distinguish between the effect of structural damping and the effect of mass ratio on the response of a body subjected to VIV. A response model for predicting IL VIV is presented based on this method. The results also reveal that IL oscillations will give rise to CF forces that contribute to an earlier start-up of CF VIV, compared to conditions where the IL motion is restrained.</p><p>The results of the second set of experiments indicate that hydrodynamic coefficients from forced oscillation experiments and the assumption that strip theory is valid, can be used to predict two degree-of-freedom response of a flexible beam. In the third set of experiments it is revealed that changing the shape and direction of the orbital path significantly changes the forces acting on the cylinder. Hydrodynamic forces at multiples of the oscillation frequency, known as higher order harmonic forces, are also measured.</p>
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Stubblefield, John M. "Numerically-based ducted propeller design using vortex lattice lifting line theory." Thesis, (2 MB), 2008. http://handle.dtic.mil/100.2/ADA488219.
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Thesis (M.S. in Naval Architecture and Marine Engineering and M.S. in Mechanical Engineering)--Massachusetts Institute of Technology, June, 2008.<br>"June 2008." Description based on title screen as viewed on August 26, 2009. DTIC Descriptor(s): Vortices, Propellers, Interactions, Theory, Theses, Lifting Surfaces, Ducts, Lattice Dynamics, Experimental Design, Numerical Methods And Procedures, Validation. DTIC Identifer(s): Ducted Propel. Includes bibliographical references (p. 49-50). Also available in print.
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Sonier, Jeffrey E. "The magnetic penetration depth and the vortex core radius in type-II superconductors." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape15/PQDD_0016/NQ27252.pdf.
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Cho, Donald L. (Donald Lee). "Effect of vortex core stagnation pressure on tip clearance flow blockage in turbomachines." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/47391.
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Castro, Alberto. "Off-line and in-operation optical core networks planning." Doctoral thesis, Universitat Politècnica de Catalunya, 2014. http://hdl.handle.net/10803/283576.
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The ever increasing IP traffic volume has finally brought to light the high inefficiency of current wavelength-routed over rigid-grid optical networks in matching the client layer requirements. Such an issue results in the deployment of large-size, expensive and power-consuming Multiprotocol Label Switching (MPLS) layers to perform the required grooming/aggregation functionality. To deal with this problem, the emerging flexgrid technology, allowing for reduced size frequency grids, is being standardized.
Flexgrid optical networks divide the spectrum into frequency slots providing finer granularity than rigid networks based on Dense Wavelength Division Multiplexing (DWDM). To find a feasible allocation, new Routing and Spectrum Allocation (RSA) algorithms for flexgrid optical networks need to be designed and evaluated. Furthermore, due to the flexibility of flexible optical networks, the aggregation functions and statistical multiplexing can be partially located in the optical layer. In addition, given the special characteristics of flexible optical networks, the traditional mechanisms for protection and recovery must be reformulated.
Optical transport platforms are designed to facilitate the setting up and tearing down of optical connections (lightpaths). Combining remotely configurable optical cross-connects (OXCs) with a control plane provides the capability of automated lightpath set-up for regular provisioning, and real-time reaction to the failures, being thus able to reduce Operational Expenditures (OPEX). However, to exploit existing capacity, increase dynamicity, and provide automation in future networks, current management architectures, utilizing legacy Network Management Systems (NMS) need to be radically transformed.
This thesis is devoted to design optical networks and to devise algorithms to operate them.
Network design objective consists of:
i. Analyzing the cost implications that a set of frequency slot widths have on the Capital Expenditures (CAPEX) investments required to deploy MPLS-over-flexgrid networks;
ii. Studying recovery schemes, where a new recovery scheme specifically designed for flexgrid-based optical networks is proposed.
As for network operation, we focus on:
i. Studying provisioning, where two provisioning algorithms are proposed: the first one targets at solving the RSA problem in flexgrid networks, whereas the second one studies provisioning considering optical impairments in translucent DWDM networks;
ii. Getting back to the recovery problem, we focus on algorithms to cope with restoration in dynamic scenarios. Several algorithms are proposed for both single layer and multilayer networks to be deployed in the centralized Path Computation Element (PCE);
iii. One of the main problems in flexgrid networks is spectrum defragmentation. In view of that, we propose an algorithm to reallocate already established optical connections so as to make room for incoming requests. This algorithm is extended with elasticity to deal with time-varying traffic.
The above algorithms are firstly implemented and validated by using simulation, and finally experimentally assessed in real test-beds. In view of PCE architectures do not facilitate network reconfiguration, we propose a control and management architecture to allow the network to be dynamically operated; network resources can be made available by reconfiguring and/or re-optimizing the network on demand and in real-time. We call that as in-operation network planning.
It shall be mentioned that part of the work reported in this thesis has been done within the framework of several European and National projects, namely STRONGEST (FP7-247674), IDEALIST (FP7-ICT-2011-8), and GEANT (FP7-238875) funded by the European Commission, and ENGINE (TEC2008-02634) and ELASTIC (TEC2011-27310) funded by the Spanish Science Ministry.<br>El volumen creciente del tráfico IP, finalmente, ha puesto de manifiesto la alta ineficiencia de las redes ópticas actuales de grid rígido basadas en WDM en la adecuación a los requisitos de capa de cliente. Dicho problema genera que se deba desplegar una red con capas MPLS de gran tamaño, costosa y de alto consumo energético para poder realizar la funcionalidad de agregación requerida. Para hacer frente a este problema, la tecnología flexgrid emergente, que permite grids con frecuencias de menor tamaño, está siendo estandarizada. Las redes ópticas flexgrid dividen el espectro en slots de frecuencia, lo que proporciona una granularidad más fina en comparación a las redes rígidas basadas en WDM. Para encontrar una asignación factible, nuevos algoritmos de enrutamiento y asignación de espectro (RSA) para redes ópticas flexgrid deben ser diseñados y evaluados. Además, debido a la flexibilidad de las redes ópticas flexibles, las funciones de agregación y de multiplexación estadística pueden ser parcialmente situadas en la capa óptica. Asimismo, dadas las características especiales de las redes ópticas flexibles, los mecanismos tradicionales de protección y recuperación deben reformularse. Las plataformas de transporte ópticas están diseñadas para facilitar la creación y destrucción de conexiones ópticas. La combinación de OXCs configurables remotamente con un plano de control, proporciona la capacidad de crear conexiones automáticamente para el aprovisionamiento habitual, y la reacción en tiempo real a los fallos, para así poder reducir el OPEX. Sin embargo, para aprovechar la capacidad existente, aumentar la dinamicidad y proporcionar automatización a las redes del futuro, las arquitecturas actuales de gestión, que utilizan sistemas legados de NMS, necesitan ser transformadas de manera radical. Esta tesis está dedicada al diseño de redes ópticas y a la creación de algoritmos para operarlas. El objetivo de diseño de red se compone de: 1. El análisis de las implicancias en el costo que tiene un conjunto de slots de frecuencia en el CAPEX necesario para implementar redes MPLS-over-flexgrid; 2. El estudio de esquemas de recuperación, donde se propone un nuevo esquema de recuperación diseñado específicamente para las redes ópticas basadas en flexgrid. En cuanto a la operación de la red: 1. El estudio de aprovisionamiento, donde se proponen dos algoritmos de aprovisionamiento: el primero de ellos tiene como objetivo solucionar el problema de RSA en redes flexgrid, mientras que el segundo estudia aprovisionamiento considerando la degradación óptica en redes WDM translúcidas; 2. Volviendo al problema de la recuperación, nos centramos en algoritmos de restauración para escenarios dinámicos. Se proponen varios algoritmos, tanto para redes mono-capa como multi-capa, que serán desplegados en un PCE centralizado; 3. Uno de los principales problemas en las redes flexgrid es la desfragmentación del espectro. Para ello, se propone un algoritmo para reasignar las conexiones ópticas ya establecidas con el fin de hacer espacio a las entrantes. Este algoritmo se extiende con elasticidad para ser utilizado en escenarios con tráfico variable en el tiempo. Los algoritmos anteriores son primero implementados y validados utilizando simulación, y finalmente son evaluados experimentalmente en testbeds reales. En vista de que las arquitecturas de PCE no facilitan la reconfiguración de la red, proponemos una arquitectura de control y gestión para permitir que la red pueda ser operada de forma dinámica; hacer que los recursos de la red estén disponibles mediante reconfiguración y/o re-optimización de la red bajo demanda y en tiempo real. A eso lo llamamos planificación en operación de la red. El trabajo presentado en esta tesis se ha realizado en el marco de proyectos europeos y nacionales: STRONGEST (FP7-247674), IDEALIST (FP7-2011-8), y GEANT (FP7-238875) financiados por la CE, y ENGINE (TEC2008-02634) y ELASTIC (TEC2011-27310) financiados por el MINECO
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Wang, Qianen, and 王乾恩. "Electronic structures of impurity and orbital-resolved vortex core states in iron-selenide superconductors." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2014. http://hdl.handle.net/10722/206433.
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We study the effect of a single non-magnetic impurity and vortex core states in iron-selenide superconductors by solving the Bogoliubov-de Gennes equations self-consistently based on a three-orbital model. Various pairing symmetry are considered in the calculation. The impurity-induced in-gap bound states are found only for attractive impurity scattering potential, as in the cases of doping of Co or Ni, which is characterized by the strong particle-hole asymmetry, in the nodeless d_(x^2-y^2 ) wave pairing state. This property may be used to probe the pairing symmetry of iron-selenide 122-type superconductors. The orbital-resolved vortex core states of different pairing symmetries manifest themselves as distinguishable structures due to different behavior of the quasiparticle wavefunctions. The obtained vortices are classified by the invariant subgroups of the symmetry group of the meanfield Hamiltonian in the presence of magnetic field as isotropic s- and s±-wave vortices have G_5 symmetry for each orbital, whereas d_(x^2-y^2 ) wave vortices show G(* )¦6 symmetry for d_xzand d_yz orbitals and G(* )¦5 symmetry for d_xy orbital. In the case of d_(x^2-y^2 ) wave vortices, hybridized-pairing between d_xzand d_yz orbitals gives rise to a relative phase difference in terms of winding structures of vortices between these two orbitals and d_xy orbital, which is essentially caused by a transformation of co-representation of G(* )¦5 and G(* )¦6 subgroup. Calculation of particle densities show common charging feature of vortices in the cases of s± and d_(x^2-y^2 ) wave pairing states where the electron-like vortices are observed for d_xz and d_yz orbitals while hole-like vortices for d_xyorbital. The phase difference of orbital-resolved d_(x^2-y^2 ) wave vortices and their charging effects can be verified by further experimental observations.<br>published_or_final_version<br>Physics<br>Doctoral<br>Doctor of Philosophy
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Chung, Hsin-Lung. "An enhanced propeller design program based on propeller vortex lattice lifting line theory." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/39729.
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Thesis (S.M. in Naval Architecture and Marine Engineering)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2007.<br>Includes bibliographical references (p. 75).<br>A suite of propeller numerical design tools was developed in MATLAB®, a high-level technical computing language. The tools were based on the FORTRAN programs developed by Professor Justin Kerwin at MIT in 2001 and include enhanced parametric design capability, Graphical User Interfaces (GUIs) and enhanced graphics capability. The MIT Propeller Vortex Lattice Lifting Line Program (PVL) is an executable file written in FORTRAN language and serves as a preliminary propeller design tool. In this thesis, PVL was rewritten in MATLAB® and presented with the GUIs. The enhancements were incorporated in a revised propeller design program designated MPVL to distinguish it from PVL. Several new features such as the user-friendly GUIs and colorful graphs were included in MPVL in addition to the full functions of PVL. Moreover, MPVL was validated by comparing its outputs with PVL and MIT Propeller Lifting Line Program (PLL) and proved to be consistent with PVL. The advantages of MPVL were revealed in this thesis and enabled MPVL to replace PVL.<br>(cont.) MPVL was developed to serve as an open source code for propeller design. It is also a base program which can be extended to perform more sophisticated propeller design applications such as ducted propellers and contra-rotating propellers. A description of the development efforts for this revised propeller design program forms the basis of this thesis.<br>by Hsin-Lung Chung.<br>S.M.<br>S.M.in Naval Architecture and Marine Engineering
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Yin, Decao. "Experimental and Numerical Analysis of Combined In-line and Cross-flow Vortex Induced Vibration." Doctoral thesis, Norges teknisk-naturvitenskapelige universitet, Centre for Ships and Ocean Structures, 2013. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-20014.
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This thesis presents results from experimental and numerical investigations of the hydrodynamic forces on a rigid cylinder moving with prescribed orbits in uniform flow. The hydrodynamic forces are measured in both in-line (IL) and cross- ow (CF) directions. The measurements are processed to nd excitation and added mass coeffcients at discrete frequencies. The numerical simulations are used to illustrate the vortex shedding modes and are compared with the experimental results. The hydrodynamic coeffcients obtained from the harmonic forced motion experiments of a rigid cylinder do not always represent forces on a cross section of a exible beam. The orbits used in the forced motion experiments are therefore extracted from the measured motions of cross sections of a exible pipe under uniform and shear flows. Both periodic and observed orbits within a time window are applied as prescribed motions. Higher order displacement components are present in such orbits. IL response amplitudes from combined IL and CF response are larger than pure IL response amplitudes. The hydrodynamic coefficients obtained from the periodic experiments are often larger than those obtained from the pure IL tests. Higher order displacement components are more common in the IL direction than in the CF direction, and higher order IL displacement components will cause larger hydrodynamic forces in both directions. The hydrodynamic coefficients obtained from periodic motion tests are adequate for representing quasi-periodic observed motions. For chaotic observed motions, periodic orbits will yield hydrodynamic coefficients with larger uncertainties. Results from numerical analyses using large eddy simulation (LES) indicate that this method can be used to identify vortex shedding patterns and predict hydrodynamic forces under certain Re numbers and orbits.
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YAMAMOTO, Kazuhiro, Masahisa SHINODA, Hiroshi YAMASHITA та ін. "ランキン渦流中での予混合火炎伝播に与える渦核半径の影響に関する数値解析". 一般社団法人 日本機械学会, 2008. http://hdl.handle.net/2237/19800.
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Najarzadegan, Farshid. "Circulation Dependence of the Interaction Between a Wing-Tip Vortex and Turbulence." UKnowledge, 2019. https://uknowledge.uky.edu/me_etds/145.
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Vortices are present in many fluid flows and depending on the context they may be either beneficial or harmful for different systems or processes. Planar particle image velocimetry was used to examine the vortex evolution and its decay under different turbulence intensities and vortex circulation. The vortex decayed faster in the presence of high turbulence intensity. Vortex trajectories were impacted by turbulence intensity and vortex strength. Trajectories with no turbulence intensity had less variation. The vortex wandering amplitude decreased with growth of vortex strength. The vortex decay was confined to the core of the vortex, with the tangential velocity at large radial distances from the vortex center being relatively constant in time. The vortex core radius had a greater rate of growth with the low turbulence intensity and lower angle of attack. The amplitude of fluctuation of the core circulation increased for the higher turbulence intensity and weaker vortex.
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Tsoi, Man. "Persistence of planar spiral waves under domain truncation near the core." Columbus, Ohio : Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1148486634.
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Yazdabadi, Paul Adi. "A study of the precessing vortex core in cyclone dust separators and a method of prevention." Thesis, Cardiff University, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.297246.
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Dahl, Jason (Jason Michael). "Vortex-induced vibration of a circular cylinder with combined in-line and cross-flow motion." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/44747.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2008.<br>Includes bibliographical references (p. 249-256).<br>Deep water, string-like, marine risers subject to strong ocean currents, suffer from vortex-induced vibrations (VIV), where vortex shedding interacts with the structural properties of the riser, resulting in large amplitude vibrations in both in-line and cross-flow directions. This thesis presents an experimental approach to model and quantify the motions and hydrodynamic forces associated with the excitation of a deep water marine riser by considering the combined cross-flow and in-line excitation of a rigid cylinder. For deep water risers, the excitation of the structure through vortex shedding can lead to a condition of dual resonance, where the vortex shedding frequency locks in to the effective natural frequency (adjusted for added mass effects) in both in-line and cross-flow directions. Large motion amplitudes are observed in this condition along with large magnitude third harmonic forces in lift. Flow visualization of the wake behind the cylinder in combined in-line and cross-flow motion, shows that third harmonic forces are caused by the relative motion of the cylinder with respect to a '2P' (two pairs of vortices) or '2T' (two triplets of vortices) shedding pattern, since vortices shed in these modes remain in close proximity to the cylinder over one cycle of motion. Forced motions of a cylinder with combined in-line and cross-flow motions are performed, generating a database of force coefficients to be used in riser VIV prediction. The assumption of dual resonance is used to predict the motions of an elastically mounted rigid cylinder using measurements from forced cylinder motions. Two passive vortex suppression methods are studied for eliminating combined cross-flow and in-line cylinder motions and suppressing large third harmonic forces.<br>by Jason Dahl.<br>Ph.D.
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Thompson, Thomas L. "Velocity measurements near the blade tip and in the tip vortex core of a hovering model rotor." Diss., Georgia Institute of Technology, 1986. http://hdl.handle.net/1853/13003.
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Bochard, Pierre. "Vortex, entropies et énergies de ligne en micromagnétisme." Thesis, Paris 11, 2015. http://www.theses.fr/2015PA112119/document.
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Cette thèse traite de questions mathématiques posées par des problèmes issus du micromagnétisme ; un thème central en est les champs de vecteur de rotationnel nul et de norme 1, qu'on voit naturellement apparaître comme configurations minimisant des énergies micromagnétiques.Le premier chapitre est motivé par la question suivante : peut-on, en dimension plus grande que deux, caractériser les champs de vecteur de rotationnel nul et de norme 1 par une formulation cinétique ?Une telle formulation a d'abord été introduite en dimension 2 dans l'article \cite{Jabin_Otto_Perthame_Line_energy_2002} de Jabin, Otto et Perthame où elle apparaît naturellement dans le cadre de la minimisation d'une énergie de type Ginzburg-Landau. Ignat et De Lellis ont ensuite montré dans \cite{DeLellis_Ignat_Regularizing_2014} qu'une telle formulation cinétique caractérise les champs de rotationnel nul et de norme 1 possédant une certaine régularité en dimension 2. Le premier chapitre de cette thèse est consacré à l'étude d'une formulation cinétique similaire en dimension quelconque ; le résultat principal en est qu'en dimension strictement plus grande que 2, cette fomulation cinétique ne caractérise non plus tous les champs de rotationnel nul et de norme 1, mais seulement les champs constants ou les vortex.La caractérsation cinétique des champs de vecteur de rotationnel nul et de norme 1 en dimension 2,prouvée par De Lellis et Ignat et que nous venons de mentionner reposait sur la notion d'entropie.Ayant obtenu une formulation cinétique en dimension quelconque, il était naturel de vouloir l'exploiter un tentant d'étendre également la notion d'entropie aux dimensions supérieures à 2. C'est ce à quoi est consacré le deuxième chapitre de cette thèse ; nous y définissons en particulier une notion d'entropie en dimension quelconque. Le point central en est la caractérisation de ces entropies par un système d'\équations aux dérivées partielles, et leur description complète en dimension 3, ainsi que la preuve pour ces entropies de propriétés tout à fait semblables à celles des entropies deux dimensionnelles.Le troisième chapitre de cette thèse, qui expose les résultats d'un travail en collaboration avec Antonin Monteil, s'intéresse à la minimisation d'\'energies de type Aviles-Giga de la forme $\mathcal_f(m)=\int_f(|m^+-m^-|)$ o\`u $m$ est un champ de rotationnel nul et de norme 1 et où $J(m)$ désigne les lignes de saut de $m$. Deux questions classiques se posent pour ce type d'énergie : la solution de viscosité de l'équation eikonale est-elle un minimiseur et l'énergie est-elle semi-continue inférieurement pour une certaine topologie. Le résutat principal de cette partie est un construction, qui nous permet en particulier de répondre par la négative à ces deux questions dans les cas où $f(t)= t^p$ avec $p \in ]0,1[$ en donnant une condition nécessaire sur $f$ pour que $\mathcal_f$ soit semi-continue inférieurement.Enfin, le dernier chapitre de cette thèse est consacré à l'étude d'une variante de l'énergie de Ginzburg-Landau introduite par Béthuel, Brezis et Helein où on a remplacé la condition de bord par une pénalisation dépendant d'un paramètre. Nous y décrivons le comportement asymptotique de l'énergie minimale qui, suivant la valeur de ce paramètre, soit se comporte comme l'énergie de Ginzburg-Landau classique en privilégiant une configuration vortex, soit privilégie au contraire une configuration singulière suivant une ligne<br>This thesis is motivated by mathematical questions arising from micromagnetism. One would say that a central topic of this thesis is curl-free vector fields taking value into the sphere. Such fields naturally arise as minimizers of micromagnetic-type energies. The first part of this thesis is motivated by the following question : can we find a kinetic formulation caracterizing curl-free vector fields taking value into the sphere in dimension greater than 2 ? Such a formulation has been found in two dimension by Jabin, Otto and Perthame in \cite. De Lellis and Ignat used this formulation in \cite{DeLellis_Ignat_Regularizing_2014} to caracterize curl-free vector fields taking value into the sphere with a given regularity. The main result of this part is the generalization of their kinetic formulation in any dimension and the proof that if $d>2$, this formulation caracterizes only constant vector fields and vorteces, i. e. vector fields of the form $\pm \frac$. The second part of this thesis is devoted to a generalization of the notion of \textit, which plays a key role in the article of De Lellis and Ignat we talked about above. We give a definition of entropy in any dimension, and prove properties quite similar to those enjoyed by the classical two-dimensional entropy. The third part of this thesis, which is the result of a joint work with Antonin Monteil, is about the study of an Aviles-Giga type energy. The main point of this part is a necessary condition for such an energy to be lower semi continuous. We give in particular an example of energy of this type for which the viscosity solution of the eikonal equation is \textit a minimizer. The last part, finally is devoted to the study of a Ginzburg-Landau type energy where we replace the boundary condition of the classical Ginzburg-Landau energy introduced by Béthuel, Brezis and Helein by a penalization within the energy at the critical scaling depending on a parameter. The core result of this part is the description of the asymptotic of the minimal energy, which, depending on the parameter, favorizes vortices-like configuration like in the classical Ginzburg-Landau case, or configurations singular along a line
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Browne, Daniel R. "Application of multi-core and cluster computing to the Transmission Line Matrix method." Thesis, Loughborough University, 2014. https://dspace.lboro.ac.uk/2134/14984.
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The Transmission Line Matrix (TLM) method is an existing and established mathematical method for conducting computational electromagnetic (CEM) simulations. TLM models Maxwell s equations by discretising the contiguous nature of an environment and its contents into individual small-scale elements and it is a computationally intensive process. This thesis focusses on parallel processing optimisations to the TLM method when considering the opposing ends of the contemporary computing hardware spectrum, namely large-scale computing systems versus small-scale mobile computing devices. Theoretical aspects covered in this thesis are: The historical development and derivation of the TLM method. A discrete random variable (DRV) for rain-drop diameter,allowing generation of a rain-field with raindrops adhering to a Gaussian size distribution, as a case study for a 3-D TLM implementation. Investigations into parallel computing strategies for accelerating TLM on large and small-scale computing platforms. Implementation aspects covered in this thesis are: A script for modelling rain-fields using free-to-use modelling software. The first known implementation of 2-D TLM on mobile computing devices. A 3-D TLM implementation designed for simulating the effects of rain-fields on extremely high frequency (EHF) band signals. By optimising both TLM solver implementations for their respective platforms, new opportunities present themselves. Rain-field simulations containing individual rain-drop geometry can be simulated, which was previously impractical due to the lengthy computation times required. Also, computationally time-intensive methods such as TLM were previously impractical on mobile computing devices. Contemporary hardware features on these devices now provide the opportunity for CEM simulations at speeds that are acceptable to end users, as well as providing a new avenue for educating relevant user cohorts via dynamic presentations of EM phenomena.
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Nguyen, Viet Anh. "Cache-conscious off-line real-time scheduling for multi-core platforms : algorithms and implementation." Thesis, Rennes 1, 2018. http://www.theses.fr/2018REN1S004/document.
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Les temps avancent et les applications temps-réel deviennent de plus en plus gourmandes en ressources. Les plate-formes multi-cœurs sont apparues dans le but de satisfaire les demandes des applications en ressources, tout en réduisant la taille, le poids, et la consommation énergétique. Le challenge le plus pertinent, lors du déploiement d'un système temps-réel sur une plate-forme multi-cœur, est de garantir les contraintes temporelles des applications temps réel strict s'exécutant sur de telles plate-formes. La difficulté de ce challenge provient d'une interdépendance entre les analyses de prédictabilité temporelle. Cette interdépendance peut être figurativement liée au problème philosophique de l'œuf et de la poule, et expliqué comme suit. L'un des pré-requis des algorithmes d'ordonnancement est le Pire Temps d'Exécution (PTE) des tâches pour déterminer leur placement et leur ordre d'exécution. Mais ce PTE est lui aussi influencé par les décisions de l'ordonnanceur qui va déterminer quelles sont les tâches co-localisées ou concurrentes propageant des effets sur les caches locaux et les ressources physiquement partagées et donc le PTE. La plupart des méthodes d'analyse pour les architectures multi-cœurs supputent un seul PTE par tâche, lequel est valide pour toutes conditions d'exécutions confondues. Cette hypothèse est beaucoup trop pessimiste pour entrevoir un gain de performance sur des architectures dotées de caches locaux. Pour de telles architectures, le PTE d'une tâche est dépendant du contenu du cache au début de l'exécution de la dite tâche, qui est lui-même dépendant de la tâche exécutée avant et ainsi de suite. Dans cette thèse, nous proposons de prendre en compte des PTEs incluant les effets des caches privés sur le contexte d’exécution de chaque tâche. Nous proposons dans cette thèse deux techniques d'ordonnancement ciblant des architectures multi-cœurs équipées de caches locaux. Ces deux techniques ordonnancent une application parallèle modélisée par un graphe de tâches, et génèrent un planning statique partitionné et non-préemptif. Nous proposons une méthode optimale à base de Programmation Linéaire en Nombre Entier (PLNE), ainsi qu'une méthode de résolution par heuristique basée sur de l'ordonnancement par liste. Les résultats expérimentaux montrent que la prise en compte des effets des caches privés sur les PTE des tâches réduit significativement la longueur des ordonnancements générés, ce comparé à leur homologue ignorant les caches locaux. Afin de parfaire les résultats ainsi obtenus, nous avons réalisé l'implémentation de nos ordonnancements dirigés par le temps et conscients du cache pour un déploiement sur une machine Kalray MPPA-256, une plate-forme multi-cœur en grappes (clusters). En premier lieu, nous avons identifié les challenges réels survenant lors de ce type d'implémentation, tel que la pollution des caches, la contention induite par le partage du bus, les délais de lancement d'une tâche introduits par la présence de l'ordonnanceur, et l'absence de cohérence des caches de données. En second lieu, nous proposons des stratégies adaptées et incluant, dans la formulation PLNE, les contraintes matérielles ; ainsi qu'une méthode permettant de générer le code final de l'application. Enfin, l'évaluation expérimentale valide la correction fonctionnelle et temporelle de notre implémentation pendant laquelle nous avons pu observé le facteur le plus impactant la longueur de l'ordonnancement: la contention<br>Nowadays, real-time applications are more compute-intensive as more functionalities are introduced. Multi-core platforms have been released to satisfy the computing demand while reducing the size, weight, and power requirements. The most significant challenge when deploying real-time systems on multi-core platforms is to guarantee the real-time constraints of hard real-time applications on such platforms. This is caused by interdependent problems, referred to as a chicken and egg situation, which is explained as follows. Due to the effect of multi-core hardware, such as local caches and shared hardware resources, the timing behavior of tasks are strongly influenced by their execution context (i.e., co-located tasks, concurrent tasks), which are determined by scheduling strategies. Symetrically, scheduling algorithms require the Worst-Case Execution Time (WCET) of tasks as prior knowledge to determine their allocation and their execution order. Most schedulability analysis techniques for multi-core architectures assume a single WCET per task, which is valid in all execution conditions. This assumption is too pessimistic for parallel applications running on multi-core architectures with local caches. In such architectures, the WCET of a task depends on the cache contents at the beginning of its execution, itself depending on the task that was executed before the task under study. In this thesis, we address the issue by proposing scheduling algorithms that take into account context-sensitive WCETs of tasks due to the effect of private caches. We propose two scheduling techniques for multi-core architectures equipped with local caches. The two techniques schedule a parallel application modeled as a task graph, and generate a static partitioned non-preemptive schedule. We propose an optimal method, using an Integer Linear Programming (ILP) formulation, as well as a heuristic method based on list scheduling. Experimental results show that by taking into account the effect of private caches on tasks’ WCETs, the length of generated schedules are significantly reduced as compared to schedules generated by cache-unaware scheduling methods. Furthermore, we perform the implementation of time-driven cache-conscious schedules on the Kalray MPPA-256 machine, a clustered many-core platform. We first identify the practical challenges arising when implementing time-driven cache-conscious schedules on the machine, including cache pollution cause by the scheduler, shared bus contention, delay to the start time of tasks, and data cache inconsistency. We then propose our strategies including an ILP formulation for adapting cache-conscious schedules to the identified practical factors, and a method for generating the code of applications to be executed on the machine. Experimental validation shows the functional and the temporal correctness of our implementation. Additionally, shared bus contention is observed to be the most impacting factor on the length of adapted cache-conscious schedules
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Fleming, Devinna Danielle, and Devinna Danielle Fleming. "Faraday Rotation in Magnetic Ionic Liquids for Liquid Core Optical In-Line Isolator Applications." Thesis, The University of Arizona, 2016. http://hdl.handle.net/10150/623082.
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A suspended ionic solution of 1-butyl-3-methylimidazolium iron tetrachloride [BMIM][FeCl4] provides a novel medium for achieving Faraday rotation under small magnetic fields at pump wavelengths of 980nm. As verified with spectrophotometry, transmission at telecommunication wavelengths makes the solution applicable across multiple applications. A cryostation was used to measure the sample up to a 340K and under field at 600mT, the ionic sample shows the necessary temperature stability and enables compact formats suitable for potential industrial applications. With a rotation of linearly polarized light of 0.04° over a 450um path length, a full 45° rotation requires only a 50.6cm path length and with only a 0.000175°/K temperature dependence. The observation of polarization effects in real time using lock-in amplifiers, and a photo-elastic modulator demonstrates the scalability, responsiveness, and stability of the ionic liquids for photonic integration. The test set up provides a convenient way to expand the research on ionic liquid Faraday rotation materials and other Faraday liquids ideally leading to a compact in-line isolator solution.
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Karki, Hemanta D. "Investigation of flow characteristics in an open channel with one-line semicircular vegetation patches." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2022. https://ro.ecu.edu.au/theses/2595.
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Experiments are conducted in an open channel with semi-circular patches distributed on one sidewall of the channel in which velocity distribution, turbulent intensity, and vortex generation are analyzed. The resistance force offered by a vegetation patch causes the change in water depth which have a broader application in river management, bank stabilization, and flood control.
The measurement is conducted in the laboratory with the help of different measuring devices like Laser doppler velocimeter, particle image velocimeter, measuring scale, and so on. From the experiment, the velocity distribution in a longitudinal direction suggests that the flow is fully developed after a certain distance from a channel inlet. When the flow passes through the vegetation patch, it forms three different regions, i.e., canopy region, interference zone, and canopy free region. The flow velocity is maximum at the interference zone because of canopy patches to the flow. Wake formation is observed behind the canopy patch, which plays a vital role in sediment deposition; further moving away in the flow direction, wake formation decreases. Velocity is unstable and very low inside the canopy region due to the resisting force. It increases while moving away from the canopy patch in the transverse direction and becomes stable in canopy free region until it reaches the sidewall. A dip phenomenon is observed for both wide and narrow channels, but a dip phenomenon for narrow channels always lies lower from the surface than for wider channels. Turbulent intensities vary with different factors like the nature of the channel, vegetation density, and vegetation stem diameter. Turbulent intensity for a wide channel is comparatively higher than the narrow channel in a canopy-free region. Also, turbulent intensity is minimum just behind the midpoint of the canopy patches, whereas it is lower for dense vegetation than sparse vegetation behind the patch. Furthermore, turbulent intensity for smaller stem diameters is lower than for larger stem diameters behind the canopy patch.
Kelvin-Helmholtz instabilities are visualized due to the change in velocity in an interference zone and play a vital role in eradicating sediments. Also, the size of instabilities depends on the dimension of patches which shows the importance of vortex generation. The width of the vortex structure is more significant in a narrow channel than in a wide channel due to the substantial flow divergence by vegetation patches. Investigation of velocity distribution, turbulent intensity, and vortex generation with canopy patches on both sides of the channel is left for future work.
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Hunsaker, Douglas F. "A Numerical Vortex Approach To Aerodynamic Modeling of SUAV/VTOL Aircraft." Diss., CLICK HERE for online access, 2007. http://contentdm.lib.byu.edu/ETD/image/etd1678.pdf.
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Siqueira, Ezequiel Costa. "Propriedades supercondutoras de sistemas multicamadas de Ni/Nb." [s.n.], 2006. http://repositorio.unicamp.br/jspui/handle/REPOSIP/277226.
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Orientador: Oscar Ferreira de Lima<br>Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin<br>Made available in DSpace on 2018-09-24T18:27:35Z (GMT). No. of bitstreams: 1
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Previous issue date: 2006<br>Resumo: O interesse em sistemas de multicamadas supercondutoras/ferromagnéticas deve-se a algumas questões importantes relacionadas com a supressão da temperatura crítica, à coexistência da supercondutividade e ferromagnetismo e às transições dimensionais da matéria de vórtices. Neste trabalho foram estudados filmes multicamadas preparados por magnetron sputtering, com fórmula geral Ni(x)[Nb(y)/Ni(x)]n, onde x e y são espessuras fixas (4 º A até 20 º A e 87 º A até 250 º A) e n é o número de bicamadas de Ni/Nb. Os filmes foram caracterizados por difração de raios X em baixo e alto ângulo e por medidas de momento magnético como função da temperatura (T) e campo (H), para orientações perpendicular e paralela às camadas. Os resultados das medidas de raios X em baixo ângulo indicaram uma boa estrutura de multicamadas tendo a espessura das bicamadas ficado dentro de 5% dos valores nominais. As medidas em alto ângulo revelaram a texturização das camadas de Ni e Nb nas direções (111) e (110), respectivamente. Este estudo foi concentrado nas transições dimensionais do acoplamento supercondutor e suas implicações sobre a matéria de vórtices. Medidas de magnetização feitas na amostra Ni(20 º A)[Nb(250 º A)/Ni(20 º A)]9 indicaram uma transição 3D-2D do sistema de vórtices, como revelado pelo comportamento do campo crítico H c2 ?? (T) paralelo às camadas. Consistentemente, foi identificada uma possível linha de desacoplamento dos vórtices associada com a transição das linhas de vórtices de Abrikosov em vórtices panquecas, para a orientação de H perpendicular às camadas. Um linha de irreversibilidade foi determinada e sugere diferentes regimes da matéria de vórtices, onde a função exercida pelas camadas ferromagnéticas de Ni pode ser relevante. Todas as amostras estudadas mostraram instabilidades no momento magnético medido, devido à forte interação entre as contribuições supercondutora, das camadas de Nb, e ferromagnética, das camadas de Ni. As amostras com espessuras de Ni menores mostraram um comportamento paramagnético evidenciandoeos efeitos de tamanho finito sobre o magnetismo das camadas de Ni. A temperatura crítica supercondutora nestas amostras (4 K < Tc< 6 K) foi reduzida em relação ao valor apresentado por uma amostra volumétrica de Nb ( Tc= 9,2 K). Em conclusão, todos os efeitos observados neste trabalho mostram uma relação muito próxima com os efeitos de tamanho finito das camadas de Ni e Nb, e com a competição entre supercondutividade e ferromagnetismo<br>Abstract: The interest in multilayered superconductor/ferromagnetic structures originates from some important questions related to the critical temperature suppression, the coexistence of superconductivity and magnetism, and dimensional transitions of the vortex matter. In this work we have studied multilayered films prepared by magnetron sputtering, with general formula Ni(x)[Nb(y)/Ni(x)]n, where x and y are fixed thicknesses (4 º A to 20 º A and 87 º A to 250 º A), and n is the number of bi-layers of Ni/Nb. The films were characterized by high and low angle X-ray diffraction and by measurements of the magnetic moment as a function of temperature (T) and magnetic field (H), for perpendicular and parallel orientations with respect to the layers. The results of low angle diffraction indicate a good multilayer structure having bi-layer thicknesses within 5% of the nominal values. The high angle results indicate that Ni and Nb layers are textured in (111) and (110) directions. In this study we have concentrated on the dimensional transitions of the superconducting phase and their effects on the vortex matter. Magnetization measurements made in the Ni(20 º A)[Nb(250 º A)/Ni(20 º A) ]9 sample indicated a 3D-2D crossover of the vortex system, as revealed by the parallel upper critical field behavior. Consistently, it was identified a possible decoupling line associated with transition of Abrikosov vortex lines into vortex pancakes, for H perpendicular to the layers. An irreversibility line was determined and it suggests different regimes of the vortex matter, where the role played by the Ni ferromagnetic layers might be relevant. All the samples studied show magnetic moment instabilities, due to the strong interplay between the superconducting Nb layers and the magnetic Ni layers. The samples with more thinner Ni layers showed a paramagnetic behavior in the normal state, revealing a finite size effect on the magnetic properties of the Ni layers. The superconducting critical temperature in those samples (4 K < Tc < 6 K) was reduced in relation to its bulk value (Tc= 9,2 K). In conclusion, all the effects observed in this work have shown a close relation with finite size effects of the Ni and Nb layers, and with the interplay between superconductivity and magnetism<br>Mestrado<br>Supercondutividade<br>Mestre em Física
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Oh, Jungju. "Efficient hardware and software assist for many-core performance." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/50219.
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In recent years, the number of available cores in a processor are increasing rapidly while the pace of performance improvement of an individual core has been lagged. It led application developers to extract more parallelism from a number of cores to make their applications run faster. However, writing a parallel program that scales well with the increasing core counts is challenging. Consequently, many parallel applications suffer from performance bugs caused by scalability limiters.
We expect core counts to continue to increase for the foreseeable future and hence, addressing scalability limiters is important for better performance on future hardware. With this thesis, I propose both software frameworks and hardware improvements that I developed to address three important scalability limiters: load imbalance, barrier latency and increasing on-chip packet latency.
First, I introduce a debugging framework for load imbalance called LIME. The LIME framework uses profiling, statistical analysis and control flow graph analysis to automatically determine the nature of load imbalance problems and pinpoint the code where the problems are introduced.
Second, I address scalability problem of the barrier, which has become costly and difficult to achieve scalable performance. To address this problem, I propose a transmission line (TL) based hardware barrier support, called TLSync, that is orders of magnitude faster than software barrier implementation while supports many (tens) of barriers simultaneously using a single chip-spanning network.
Third and lastly, I focus on the increasing packet latency in on-chip network, and propose a hybrid interconnection where a low-latency TL based interconnect is synergistically used with a high-throughput switched interconnect. Also, a new adaptive packet steering policy is created to judiciously use the limited throughput available on the low-latency TL interconnect.
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Mohamed, Jainulabdeen Mohammed Abdul Kadher. "Combustion Noise and Instabilities from Confined Non-premixed Swirl Flames." University of Cincinnati / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1560867354695989.
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Кондусь, Владислав Юрійович, Владислав Юрьевич Кондусь, Vladyslav Yuriiovych Kondus, Олександр Іванович Котенко, Александр Иванович Котенко та Oleksandr Ivanovych Kotenko. "Перспективи створення параметричного ряду вільновихрових насосів". Thesis, ТОВ "Глобус-Прес", 2015. http://essuir.sumdu.edu.ua/handle/123456789/43320.
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Щоб скоротити до мінімуму кількість типорозмірів виробів, які випускаються промисловістю і внести одноманітність в їх конструкцію, у міжнародній практиці вважається за доцільне випускати не один який-небудь виріб, а достатньо широкий параметричний ряд. В статті розглянутий перспективний параметричний ряд для вільновихрових насосів, які призначені для перекачування рідин з високим складом абразивних включень, суспензій з великим вмістом твердих речовин і волокнистих включень, рідин з підвищеною в'язкістю, рідин з високим вмістом повітря або газу, рідин чутливих до зрізу та рідин, що містять крихкі речовини.<br>Чтобы сократить до минимума количество типоразмеров изделий, выпускаемых промышленностью и внести единообразие в их конструкцию, в международной практике считается целесообразным выпускать не одно какое-либо изделие, а достаточно широкий параметрический ряд. В статье рассмотрен перспективный параметрический ряд для свободновихревых насосов, предназначенных для перекачки жидкостей с высоким составом абразивных включений, суспензий с большим содержанием твердых веществ и волокнистых включений, жидкостей с повышенной вязкостью, жидкостей с высоким содержанием воздуха или газа, жидкостей чувствительных к срезу и жидкостей, содержащих хрупкие вещества.
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Natarajan, Saravana Prakash. "Micro coaxial transmission lines for integrated microwave circuits." [Tampa, Fla.] : University of South Florida, 2007. http://purl.fcla.edu/usf/dc/et/SFE0002265.
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RAVASIO, CLAUDIA. "OPTICAL CHARACTERIZATION OF MINERAL DUST CONTENT IN SNOW AND ICE CORES WITH DIGITAL IN-LINE HOLOGRAPHY." Doctoral thesis, Università degli Studi di Milano, 2022. http://hdl.handle.net/2434/916834.
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Aerosols are ubiquitous in the troposphere and influence the global climate by changing the radiative properties of the atmosphere: directly, through the scattering and absorption of solar and terrestrial radiation, and indirectly acting as cloud condensation and ice nuclei formation. Although extensive research has been carried out on this topic, significant uncertainties still affect current estimates of this contribution on the Earth’s energy balance.
In this work, I studied the effects of the particle shape on the optical parameters for the radiative transfer through the atmosphere. I present the results of the characterization of mineral dust and micrometric particles transported and subsequently deposited on the surface of glaciers, and in time brought deeper, layer after layer. To this end, digital microscopic holography has proven to be an excellent suite for distinguishing non-spherical particles, going beyond the common spherical approximation. From the interference between the trans-illuminating reference field and the diffracted light by the particles in the forward direction, the cross-sectional area and the extinction cross-section can be numerically retrieved, thus providing a multi-parametric single-particle approach.
This work develops a formal description of the technique through the theory of image formation in holographic microscopy, reporting a suite of validation measurements with calibrated particles, and providing an overview of the experimental results from Antarctic and Alpine snow and ice cores. The analysis reveals a remarkable variability in the extinction cross-section of the particles depending on their shape, with a prevalence of non-spherical particles, which proves the importance of measuring morphological and optical properties simultaneously. I also observed a prevalence of fine particles (< 2 μm in size), with the occurrence of aggregates and some giant particles (> 10 μm in size), especially in Alpine snow cores.
Currently, global and regional models assume dust particles as uniform spheres, and neglect the coarsest particles, introducing biases in the estimation of the radiative effects. Therefore, they will benefit from more accurate modeling of particle size and shapes, especially if obtained from the optical properties themselves.
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Watton, Timothy James. "A multidisciplinary assessment of hyaloclastite deposits in petroleum systems using field studies, drill core, borehole image and wire-line log datasets." Thesis, Durham University, 2013. http://etheses.dur.ac.uk/7762/.
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This thesis aims to document hyaloclastite deposits in different depositional environments from field outcrops in Iceland to characterise lithofacies heterogeneity enabling comparison to subsurface datasets. Field hyaloclastite datasets from Stóri-Núpur (subaerial-marine transition) and Hjörleifshöfði (an emergent Surtseyan volcano) are used to support the interpretation of hyaloclastite and associated volcanic deposits in core, borehole image logs and wire-line log datasets from Hawaii (Hawaiian Scientific Drilling Project II – HSDP II borehole) and the Faroe-Shetland Basin (LOPRA1/1A well and the Rosebank field). This study provides additional constraints on lava delta formation in predominantly basaltic systems where hyaloclastite depositional profiles reflect localised extrusion pathways and syn-sediment reworking which control 3D lithofacies architecture. Furthermore this thesis documents the evolution of Hjörleifshöfði using field mapping and major/trace element geochemistry. Hjörleifshöfði can split into five phases of deposition charting the submarine to emergent building of the volcano, unique as it also records a phase of silicic volcanism (Sólheimar Ignimbrite) which dates late stage volcanism to no earlier than 12,383 C14 years BP. Petrophysical and petrographic observations suggest hyaloclastite deposits are unique in terms of their velocity/density and P and S wave relationships due to palagonite formation, basalt clast support, phenocryst and zeolite component amongst others which impacts on depth conversion and the calculation of reflection coefficients. Wire-line log response gamma-ray (GR), resistivity (RES), P-wave sonic velocity (Vp) is also closely linked to the dominant interstitial secondary minerals and phenocryst components of sideromelane glass. Borehole image log analysis of mixed volcanic and volcaniclastic rocks allows the accurate characterisation of distinct internal lava flow features, contact relationships and joint networks enabling better characterisation of volcanic sequences in the subsurface via careful comparison with field examples. Field, core and wire-line log data is combined to form a multidisciplinary assessment of hyaloclastite deposits in the subsurface suggesting that the complexity and scaling issues in hyaloclastite rocks is generally overlooked which may impact on future petroleum exploration in volcanic basins.
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Ribeiro, Richard Duarte. "Recurrent Communities of Practice (RCoPs) and Transient Core Members (TCMs) : temporal behaviour of co-located and on-line Communities of Practice." Thesis, University of York, 2011. http://etheses.whiterose.ac.uk/4382/.
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Knowledge is a powerful tool, especially within companies and institutions. It has long been recognised that much of the knowledge of a company is embedded in the skills and practices of individuals and groups of individuals that share common interests. In some cases, these groupings can cross traditional organizational boundaries. These communities, known as Communities of Practice (CoPs), have a significant potential for companies and institutions. Although studied for years now, Communities of Practice are still poorly understood. Specifically, there has been little research into the dynamic, temporal aspects of how communities form, their patterns of activity and how they cease to exist. Such understanding is crucial for the successful use of CoPs within companies and institutions. Therefore, this thesis looks at the temporal aspects of Communities of Practice (CoPs). This is carried out by studying a co-located CoP, and four CoPs located within electronic networks. The study led to a rediscovery of the already known concept of CoPs’ core members, which refers to the members with strong participation in the community’s life. This work also identified two completely novel aspects related to the temporal aspects of Communities of Practice. The first one was called Recurrent Communities of Practice (RCoPs). This refers to a new class of CoPs found inside the studied co-located Community of Practice (CoP). Recurrent CoPs are Communities of Practice that work over a specific period of time, ceasing their activity until a trigger starts a new period, repeating these two states over time. The Recurrent CoPs usually have the same participants in different periods of activity. The second new concept was named Transient Core Members (TCMs). This refers to a community’s isolated members that do not engage in the community’s activity constantly, but rather in “bursts” over time, similarly to RCoPs. It is hoped that the procedures and methods explained in this work might help the development for new tools for researchers and professionals to detect and nurture Communities of Practice (CoPs) and Recurrent Communities of Practice (RCoPs). Specifically, the research expands our understanding of the temporal aspects of Communities of Practice, seldom discussed previously in the area.
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Di, Scala Nicolas. "TRANSITION DE DÉPIÉGEAGE DANS LES RÉSEAUX DE VORTEX SUPRACONDUCTEURS : ÉTUDE PAR SIMULATION NUMÉRIQUE." Phd thesis, Université François Rabelais - Tours, 2012. http://tel.archives-ouvertes.fr/tel-00741545.
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Cette étude traite du dépiégeage et de la dynamique des systèmes élastiques désordonnés. Ce cadre regroupe une large classe de systèmes allant des interfaces (telles que les parois de domaines dans les systèmes magnétiques ou ferroélectriques) aux systèmes périodiques (comme les réseaux de vortex dans les supraconducteur de type II, les colloïdes ou encore les cristaux de Wigner). Dans ces systèmes, la compétition entre l'élasticité de la structure qui veut imposer un ordre parfait et le désordre induit une grande richesse dans le diagramme de phase. L'étude est menée par simulations numériques à grande échelle, dans lesquelles nous nous intéresserons spéci fiquement aux réseaux 2D de vortex supraconducteurs. Deux types de dépiégeage sont observés lorsque l'on met en mouvement ces réseaux à l'aide d'une force extérieure : un dépiégeage plastique et un dépiégeage élastique. Nous portons notre attention sur la transition de dépiégeage élastique obtenue dans le cas d'un piégeage faible. A travers une analyse en loi d'échelle à température nulle et à température nie nous montrons le caractère continu de la transition. Divers exposants critiques sont déterminés dont l'exposant et caractérisant la dépendance en force et en température de la vitesse ou bien l'exposant caractérisant la divergence de la longueur de corrélation du système. Un modèle visco-élastique simple permettant de décrire la plasticité dans les systèmes périodiques évoluant sur un potentiel de piégeage en présence de désordre fort est également développé. Une grande variété de comportements dynamiques, similaires à ceux observés à plus grande échelle dans des systèmes périodiques, peuvent être extraits d'un tel modèle. Un dépiégeage élastique ou plastique est observé, de l'hystérésis est mesurée dans le cas du dépiégeage élastique, et du chaos est détecté pour le dépiégeage plastique.
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Nascimento, Leandro Marques do. "Cores assets development in software product lines - towards a practical approach for the mobile game domain." Universidade Federal de Pernambuco, 2008. https://repositorio.ufpe.br/handle/123456789/1683.
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Made available in DSpace on 2014-06-12T15:51:50Z (GMT). No. of bitstreams: 1
license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5)
Previous issue date: 2008<br>Os mais almejados objetivos da engenharia de software são basicamente alta
produtividade, com alta qualidade a um baixo custo e uma possível forma de
atingi-los é estabelecer reuso de software o processo de criar sistemas de software
a partir de sistemas existentes ao invés de criar do início. Neste contexto,
uma abordagem que pode habilitar reuso na prática é Linha de Produto de Software
(LPS) um conjunto de sistemas de software que compartilham um conjunto
comum e gerenciado de funcionalidades que satisfazem uma necessidade
específica de um domínio, e que são desenvolvidas a partir de um conjunto de
artefatos reusáveis. Um domínio em particular onde a adoção de tal abordagem
pode trazer benefícios é o domínio de jogos móveis principalmente porque os jogos
precisam executar em diversos dispositivos e existe uma grande quantidade
de jogos do mesmo tipo sendo desenvolvidos com funcionalidades em comum.
Entretanto, as características do domínio de jogos móveis geralmente
criam barreiras para os processos de LPS na prática, tais como, restrições de
memória e de tamanho da aplicação e diferentes implementações de API feitas
por diferentes fabricantes. Além disso, os atuais processos de LPS ainda carecem
de detalhes em fases relacionadas à implementação de artefatos reusáveis,
dificultando a administração apropriada das características mencionadas.
Dessa forma, este trabalho objetiva definir uma abordagem prática para
implementação de artefatos reusáveis em uma LPS para o domínio de jogos móveis
com base nas boas práticas do estado da arte na área. Além disso, com a intenção
de avaliar a abordagem, um estudo experimental foi executado com três
jogos de plataforma para construir a LPS e um quarto jogo foi derivado dela
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Midgley, Kristofer. "An isothermal experimental study of the unsteady fluid mechanics of gas turbine fuel injector flowfields." Thesis, Loughborough University, 2005. https://dspace.lboro.ac.uk/2134/10755.
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Low-emissions combustor design is crucially important to gas turbine engine manufacturers. Unfortunately, many designs are susceptible to unsteady oscillations that can result in structural fatigue and increased noise. Computational approaches that resolve flow unsteadiness, for example Large Eddy Simulation (LES), are being explored as one avenue to help understand such phenomena. However, in order to quantifY the accuracy of LES predictions, benchmark validation data in suitably chosen test cases are required. Comprehensive experimental data covering both time-averaged and timeresolved features are currently scarce. It was the aim of this thesis, therefore, to provide such data .in a configuration representing the near-field of a typical gas turbine fuel injector. It was decided to focus on the fuel injector since many unsteady events are believed to originate because of the transient interactions between the fuel injector flow and the main combustor flow. A radial fed two-stream fuel injector, based on a preexisting industrial gas-turbine Turbomeca design was used, since this geometry was known to be susceptible to unsteadiness. The fuel injector was investigated under isothermal conditions to place emphasis on the fluid mechanical behaviour of the fuel injector, including detailed capture of any unsteady phenomena present. Light Sheet Imaging (LSI) systems were used as the primary experimental technique to provide high quality spatially and temporally resolved instantaneous velocity and scalar field information in 2D planes (using ParticieImage Velocimetry (PIV) and Planar LaserInduced Fluorescence (PUF) techniques). Several methods were employed to extract information quantifYing the flow unsteadiness and improve visualisation of timedependent large-scale turbulent structures. Proper Orthogonal Decomposition (POD) analysis enabled clear identification of the dominant modes of energy containing structures. The results indicated that periodic high-energy containing vortex structures occurred in the swirl stream shear layer, emerging from the fuel injector. These formed a two-strong two-weak rotating vortex pattern which propagated down the main duct flow path. The formation of these vortices was found to be a function of the swirl number and originated due to an interaction between the forward moving swirl flow and the furthest upstream penetration point ofthe recirculation zone present in the main duct flow. Dependent on the magnitude of the swirl number (influencing the swirl stream cone angle) and the geometry of the fuel injector, the vortex formation point was sometimes found inside the fuel injector itself. If the vortices originated inside the fuel injector they appeared much more coherent in space and time and of higher energy. A second unsteady high energy containing phenomenon was also identified, namely a Precessing Vortex Core (PVC), which was damped out if the fuel injector contained a central jet. The dynamics of the PVC interacted with the dynamics of the swirl stream shear layer vortices to reduce there strength. Transient scalar measurements indicated that there was a clear connection between the unsteady vortex pattern and the rate of mixing, resulting in bursts of high heat release and is therefore identified as one source of combustor oscillations. Future fuel injector designs need to pay close attention to these unsteady features in selecting swirl number and internal geometry parameters.
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Кондусь, Владислав Юрійович, Владислав Юрьевич Кондусь, Vladyslav Yuriiovych Kondus, Олександр Іванович Котенко, Александр Иванович Котенко та Oleksandr Ivanovych Kotenko. "Вдосконалення типорозмірного ряду вільновихрових насосів (СВН) для перекачування забруднених рідин та рідин, що містять включення". Thesis, НТУУ "КПІ", 2016. http://essuir.sumdu.edu.ua/handle/123456789/45126.
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В статті розглянуто перспективи вдосконалення типорозмірного ряду вільновихрових насосів з використанням методу чисельного дослідження.<br>В статье рассмотрены перспективы совершенствования типоразмерного ряда свободновихревых насосов с использованием метода численного исследования.<br>The article deals with prospects for improvement the pump line of vortex pumps using the method of numerical investigation.
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Cruz, Fabiana Sanches. "Estudo do escoamento de gás no interior de ciclones através da técnica de fluidodinâmica computacional." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/3/3137/tde-30072013-220253/.
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Neste trabalho, buscou-se investigar a aplicação de uma modelagem RANS, com a utilização do modelo de turbulência das Tensões de Reynolds (RSTM), na modelagem do escoamento de gás no interior de ciclones, especialmente na simulação do movimento periódico do vórtice, conhecido como Precessing Vortex Core (PVC), com apoio da Fluidodinâmica Computacional. Utilizou-se o pacote de CFD de código aberto OpenFOAM, e as simulações foram realizadas em regime transiente. Dois modelos RSTM foram testados, o modelo LRR com os valores padrões para as constantes e uma modificação das constantes do termo de redistribuição. Compararam-se os resultados obtidos com dados da literatura e verificou-se que ambos os modelos representaram o campo médio de velocidade. No entanto, somente o modelo LRR conseguiu reproduzir o campo de flutuações de velocidade. Detectou-se o movimento de precessão do vórtice, que pode ser visualizado através de imagens sequenciais do escoamento, e uma frequência característica do movimento pode ser calculada através do Espectro de potência.<br>The flow field of a gas cyclone was simulated with a RANS model using Computational Fluid Dynamics (CFD) and the Precession of the Vortex Core (PVC) was investigated. The CFD simulations were carried out using the open source code OpenFOAM and the simulations were performed in a transient regime. Two Reynolds Stress Turbulence Models (RSTM) were investigated - the LRR model with standard constants and another with modified constants in the pressure-strain term. The results obtained by the models were compared with values of mean velocity taken from the literature and predictions were satisfactory. However, only the LRR model with standard constants predicted with precision the fluctuation velocity field. The precessing vortex was detected and illustrated by the flow field visualization and a characteristic frequency was calculated by Power Spectrum Density.
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Johansson, Annika. "Det handlar om att ge och ta : fyra lärarperspektiv." Thesis, Södertörn University College, Lärarutbildningen, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:sh:diva-1443.
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<p>This study deals with integration between core subjects and character subjects on the upper secondary schools Electrical Engineering Programme. The purpose is to investigate how four teachers define subject integration, which the advantages and disadvantages are according to them and what the purpose is whit integrate the core subjects and the character subjects.</p><p>The finding in this study highlighted that between themselves the teachers had different definitions of subject integration. In order to start up with a integrated working model the teachers had to come up whit a mutual definition of subject integration.</p>
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HENKE, EV. "Knock out - a missing C1s line in the photoelectron spectrum of aqueous chloral hydrate : Core electron spectroscopy of chloral hydrate, trichloroethanol and ethanol in aqueous solution and gas phase." Thesis, Uppsala University, Department of Physics and Astronomy, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-126257.
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<p>Chloral hydrate Cl3C-C(OH)2H in aqueous solution has been studied by photoelectron spectroscopy using synchrotron radiation. The expected separation between the two carbon 1s lines due to different chemical environments could not be observed in the aqueous solution, but was clearly seen in following gas phase measurements. NMR measurements excluded sample damage in the aqueous solution and support the image of coincidence of the two carbon lines. The coincidence of the two lines is discussed in terms of experimental resolution and change in chemical shift in the aqueous phase. The observations are further compared to measurements of trichloroethanol and ethanol, which both exhibit the same characteristic C-C bond and at least one hydroxyl group. The present data showed no clear evidence of change in chemical shift in aqueous solution as compared to the gas phase, but such an effect might not be completely excluded.</p><p>The liquid measurements were performed using a liquid micro-jet, a recently developed technique for accessing volatile liquids in a high vacuum environment as required for photoelectron spectroscopy. The set-up is described in detail.</p><p>During the present project, I was involved into planning and performing experiments, sample preparation, data analysis and discussion.</p>
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Lückoff, Finn Simon [Verfasser], Kilian [Akademischer Betreuer] Oberleithner, Christian Oliver [Akademischer Betreuer] Paschereit, et al. "Active flow control as a tool to reveal the role of the precessing vortex core in swirl flames / Finn Simon Lückoff ; Gutachter: Kilian Oberleithner, Christian Oliver Paschereit, Michael Steinberg, Maarten Vanierschot ; Kilian Oberleithner, Christian Oliver Paschereit." Berlin : Technische Universität Berlin, 2021. http://d-nb.info/1238141137/34.
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Mortensen, Clifton H. "A Computational Fluid Dynamics Feature Extraction Method Using Subjective Logic." BYU ScholarsArchive, 2010. https://scholarsarchive.byu.edu/etd/2208.
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Computational fluid dynamics simulations are advancing to correctly simulate highly complex fluid flow problems that can require weeks of computation on expensive high performance clusters. These simulations can generate terabytes of data and pose a severe challenge to a researcher analyzing the data. Presented in this document is a general method to extract computational fluid dynamics flow features concurrent with a simulation and as a post-processing step to drastically reduce researcher post-processing time. This general method uses software agents governed by subjective logic to make decisions about extracted features in converging and converged data sets. The software agents are designed to work inside the Concurrent Agent-enabled Feature Extraction concept and operate efficiently on massively parallel high performance computing clusters. Also presented is a specific application of the general feature extraction method to vortex core lines. Each agent's belief tuple is quantified using a pre-defined set of information. The information and functions necessary to set each component in each agent's belief tuple is given along with an explanation of the methods for setting the components. A simulation of a blunt fin is run showing convergence of the horseshoe vortex core to its final spatial location at 60% of the converged solution. Agents correctly select between two vortex core extraction algorithms and correctly identify the expected probabilities of vortex cores as the solution converges. A simulation of a delta wing is run showing coherently extracted primary vortex cores as early as 16% of the converged solution. Agents select primary vortex cores extracted by the Sujudi-Haimes algorithm as the most probable primary cores. These simulations show concurrent feature extraction is possible and that intelligent agents following the general feature extraction method are able to make appropriate decisions about converging and converged features based on pre-defined information.
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Ivanell, Stefan S. A. "Numerical computations of wind turbine wakes." Licentiate thesis, Stockholm : Royal Institute of Technology, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-316.
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Davison, Benjamin Kenneth. "Universal graph literacy: understanding how blind and low vision students can satisfy the common core standards with accessible auditory graphs." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/47621.
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Auditory graphs and active point estimation provide an inexpensive, accessible alternative for low vision and blind K-12 students using number lines and coordinate graphs. In the first phase of this research program, a series of four psychophysics studies demonstrated an interactive auditory number line that enables blind, low vision, and sighted people to find small targets with a laptop, headphones, and a mouse or a keyboard. The Fitts' Law studies showed that, given appropriate auditory feedback, blind people can use a mouse. In addition, auditory feedback can generate target response patterns similar to when people use visual feedback. Phase two introduced SQUARE, a novel method for building accessible alternatives to existing education technologies. The standards-driven and teacher-directed approach generated 17 graphing standards for sixth grade mathematics, all of which emphasized point estimation. It also showed that how only few basic behavioral components are necessary for these graphing problems. The third phase evaluated active point estimation tools in terms of training, classroom situations, and a testing situation. This work shows that students can learn to graph in K-12 environments, regardless of their visual impairment. It also provides several technologies used for graphing, and methods to further develop education accessibility research.
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Munir, Qaiser, and Muhammad Shahid. "Software Product Line:Survey of Tools." Thesis, Linköping University, Department of Computer and Information Science, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-57888.
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<p>software product line is a set of software-intensive systems that share a common, managed set of features satisfying the specificneeds of a particular market segment or mission. The main attractive part of SPL is developing a set of common assets which includes requirements, design, test plans, test cases, reusable software components and other artifacts. Tools for the development of softwareproduct line are very few in number. The purpose of these tools is to support the creation, maintenance and using different versions ofproduct line artifacts. This requires a development environment that supports the management of assets and product development,processes and sharing of assets among different products.</p><p>The objective of this master thesis is to investigate the available tools which support Software Product Line process and itsdevelopment phases. The work is carried out in two steps, in the first step available Software Product Line tools are explored and a list of tools is prepared, managed and a brief introduction of each tool is presented. The tools are classified into different categoriesaccording to their usage, relation between the tools is established for better organization and understanding. In the second step, two tools Pure::variant and MetaEdit+ are selected and the quality factors such as Usability, Performance, Reliability, MemoryConsumption and Capacity are evaluated.</p>
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Galuška, Jiří. "Modelování vtokových vírů." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2017. http://www.nusl.cz/ntk/nusl-318713.
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This paper covers information research of basic design rules of industrial wet sumps. It describes mathematical models of vortices and method for their identification and visualization. Then the author focuses on CFD modeling of surface vortices with single phase and multiphase approach with Volume of Fluid method. Basic principles of multiphase CFD modelling in OpenFOAM and ANSYS Fluent are given. Description and benchmarking of suitable turbulence models is also present. The single phase and multiphase approach were successfully validated for a simple test case of bathtub surface vortex. Satisfactory agreement with experimental data was achieved. The accuracy and behavior of both solvers were compared between each other. This gives us useful tool for evaluation of inflow condition and danger of surface vortex occurrence in wet sumps. The acquired knowledges were used to design an experimental test case with geometry similar to industrial wet sump. A map of surface vortex occurrence has been created for different operating points. One of the operating point has been used for numerical simulation (both single phase and multiphase). Partial agreement with experimental observation has been achieved.
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Cheng, Liangta. "Combined PIV/PLIF measurements in a high-swirl fuel injector flowfield." Thesis, Loughborough University, 2013. https://dspace.lboro.ac.uk/2134/11936.
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Current lean-premixed fuel injector designs have shown great potential in terms of reducing emissions of pollutants, but such designs are susceptible to combustion instabilities in which aerodynamic instability plays a major role and also has an effect on mixing of air and fuel. In comparison to prototype testing with combustors running in operating conditions, computational approaches such as Large Eddy Simulations (LES) offer a much more cost-effective alternative in the design stage. However, computational models employed by LES require validation by experimental data. This is one of the main motivations behind the present experimental study. Combined particle image velocimetry (PIV) and planar laser induced fluorescence (PLIF) instrumentation allowed simultaneous measurements of velocity vector and a conserved scalar introduced into the fuel stream. The results show that the inner swirl shear layer features two pairs of vortices, which draw high concentration fuel mixture from the central jet into the swirl stream and causes it to rotate in their wakes. Such periodic entrainment also occurs with the characteristic frequencies of the vortices. This has clear implications for temporal variations in fuel/air ratio in a combusting flow; these bursts of mixing, and hence heat release, could be a possible cause of mixing-induced pressure oscillation in combusting tests. For the first time in such a flow, all 3 components of the turbulent scalar flux were available for validation of LES-based predictions. A careful assessment of experimental errors, particularly the error associated with spatial filtering, was carried out. Comparison of LES predictions with experimental data showed very good agreement for both 1st and 2nd moment statistics, as well as spectra and scalar pdfs. It is particularly noteworthy that comparison between LES computed and measured scalar fluxes was very good; this represents successful validation of the simple (constant Schmidt number) SGS model used for this complex and practically important fuel injector flow. In addition to providing benchmark data for the validation of LES predictions, a new experimental technique has been developed that is capable of providing spatially resolved residence time data. Residence times of combustors have commonly been used to help understand NOx emissions and can also contribute to combustion instabilities. Both the time mean velocity and turbulence fields are important to the residence time, but determining the residence time via analysis of a measured velocity field is difficult due to the inherent unsteadiness and the three dimensional nature of a high-Re swirling flow. A more direct approach to measure residence time is reported here that examines the dynamic response of fuel concentration to a sudden cutoff in the fuel injection. Residence time measurement was mainly taken using a time-resolved PLIF technique, but a second camera for PIV was added to check that the step change does not alter the velocity field and the spectral content of the coherent structures. Characteristic timescales evaluated from the measurements are referred to as convection and half-life times: The former describes the time delay from a fuel injector exit reference point to a downstream point of interest, and the latter describes the rate of decay once the effect of the reduced scalar concentration at the injection source has been transported to the point of interest. Residence time is often defined as the time taken for a conserved scalar to reduce to half its initial value after injection is stopped: this is equivalent to the sum of the convection time and the half-life values. The technique was applied to a high-swirl fuel injector typical of that found in combustor applications. Two test cases have been studied: with central jet (with-jet) and without central jet (no-jet). It was found that the relatively unstable central recirculation zone of the no-jet case resulted in increased transport of fuel into the central region that is dominated by a precessing vortex core, where long half-life times are also found. Based on this, it was inferred that the no-jet case may be more prone to NOx production. The technique is described here for a single-phase isothermal flow field, but with consideration, it could be extended to studying reacting flows to provide more insight into important mixing phenomena and relevant timescales.
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Thrane, Bard Peter. "Propriétés de couches minces supraconductrices de YBa2Cu3O(7-delta) : étude structurale par diffraction des rayons X ; phénoménologie des vortex étudiée par aimantation et par absorption micro-onde sous champ magnétique." Grenoble INPG, 1996. http://www.theses.fr/1996INPG0047.
Full textAbstract:
Nous avons etudie des proprietes de couches minces supraconductrices de yba#2cu#3o#7#-# a haute temperature critique. Les films ont ete prepares par depot chimique en phase vapeur, par ablation laser, par co-evaporation et par pulverisation cathodique sur differents substrats ; l'epaisseur des films est comprise entre 5 nm et 350 nm. L'epaisseur des films a ete determinee pour des couches d'epaisseur inferieure a 100 nm par reflectometrie des rayons x. La relation d'epitaxie et les proprietes des macles ont ete etudiees par diffraction des rayons x en incidence rasante pour des films deposes sur des substrats de symetrie differente. Nous avons determine les parametres de maille dans le plan du film pour les films dont l'axe #c est perpendiculaire a ce plan. Les proprietes magnetiques ont ete etudiees entre 4,2 k et la temperature critique des films minces au moyen de magnetometres a echantillon vibrant en champ magnetique applique perpendiculaire et oblique par rapport au plan du film. Nous obtenons la ligne d'irreversibilite au voisinage de la temperature critique ; le champ d'irreversibilite croit suivant une loi en racine carree de l'epaisseur. A basse temperature sous champ magnetique applique oblique, l'aimantation des films supraconducteurs depend uniquement de la composante du champ perpendiculaire a la surface. Au voisinage de la temperature critique, nous observons une augmentation de l'aimantation irreversible lorsque l'angle entre le champ magnetique et le plan du film diminue ; ceci est attribue a l'augmentation de la longueur des vortex se trouvant entre les plans supraconducteurs qui renforcerait l'ancrage des vortex. L'analyse spectrale de la puissance micro-onde reflechie modulee par un champ magnetique alternatif, permet d'identifier un signal a la frequence d'excitation et des harmoniques paires. Nous avons demontre que le champ magnetique pour lequel les harmoniques paires disparaissent correspond au champ d'irreversibilite determine par les mesures d'aimantation irreversible