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Ton, Cuong. "Radar cross section (RCS) simulation for wind turbines." Monterey, California: Naval Postgraduate School, 2013. http://hdl.handle.net/10945/34754.
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Approved for public release; distribution is unlimitedWind-turbine power provides energy-independence and greenhouse-gas reduction benefits, but if wind turbines are built near military and commercial radar and communication installations, they can cause degradation in the systems performance. The purpose of this research is to study the radar cross section (RCS) of a wind turbine and assess its effect on the performance of radar and communication systems. In this research, some basic scattering characteristics of wind turbines are discussed. Several computational methods of RCS prediction are examined, citing their advantages and disadvantages. Modeling and computational issues that affect the accuracy and convergence of the simulation results are discussed. RCS simulation results for two wind turbine configurations are presented: a horizontal axis, three-blade design and a vertical axis helical design. Several methods of mitigating wind turbine clutter are discussed. Issues of RCS reduction and control for wind turbines are also addressed.
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Al-Asad, Zahir. "Implementation of NURBS Objects in a Ray TracingCode for RCS Simulation." Thesis, Högskolan i Gävle, Ämnesavdelningen för elektronik, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-7713.
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Hanslík, Radovan. "Odrazná plocha osobních automobilů." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2019. http://www.nusl.cz/ntk/nusl-400701.
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This diploma thesis is aimed at radar cross section of passenger cars. Basic scattering parameters of simple targets are described. Some numeric methods used for computing radar cross section are discussed. CST Microwave Studio is used for simulation of passenger car with two different solvers. For the results there are plots of radar cross section of a car for 1 GHz, 24.125 GHz and 33 GHz. There is a plot of visualized hotspots.
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Lindgren, Jonas. "Evaluation of CST Studio Suite for simulation of radar cross-section." Thesis, Umeå universitet, Institutionen för fysik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-187751.
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When designing military vehicles, it is of interest to make the vehicles difficult to detect using radar. The radar cross-section (RCS) property indicates how easily a vehicle is detected by radar and should thus be minimized. However, the RCS of a vehicle represents the cross-sectional area of a perfectly reflecting sphere that would produce the same reflection strength as the vehicle in question. Since this is extremely complicated to calculate as military vehicles are quite complex, these calculations are performed using computational simulations. BAE Systems Hägglunds is looking into changing from their current simulation software OPTISCAT to CST Studio Suite and thus want to know how CST performs and compares against OPTISCAT. In this work, we show that CST obtains results within 2% of theoretical data when simulating a sphere and a slab. When simulating vehicles, the RCS difference between the two software is from 3% to 55% while showing similar general behavior. Results indicate that CST performs well when simulating simple objects but deviates from OPTISCAT when simulating the vehicle. It is not surprising that the software does not match up perfectly since they use different theoretical approaches, OPTISCAT uses physical optics while CST an extension to physical optics called the Shooting Bouncing Ray method. Even though the software differs to this extent it is most likely possible that CST can be a suitable replacement for OPTISCAT. When looking at RCS the important part is the location of spikes and since they have similar general behavior, those spikes may still be possible to identify. This thesis will hopefully act as a starting point for further examination of CST as a software for simulating RCS, for example by comparing results from CST to experimentally measured data. Hopefully it will also be used to improve the design process of making military vehicles harder to detect.
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Salhani, Mohamad. "Modélisation et simulation des réseaux mobiles de 4ème [quatrième] génération." Phd thesis, Toulouse, INPT, 2008. http://oatao.univ-toulouse.fr/7725/1/salhani.pdf.
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Cette thèse porte sur l'interopérabilité et la qualité de service dans les réseaux de 4ème génération. En particulier, nous proposons des solutions d'intégration entre le réseau WiMAX et le système satellite DVB-RCS en s'appuyant sur le standard IEEE 802.21. Trois solutions peuvent être mises en place pour l'interconnexion de réseaux sans fil. Il s'agit de la technologie GAN soutenue par le 3GPP, du protocole FMIP proposé par l'IETF et du standard IEEE 802.21. Notre choix se porte sur ce denier standard car il propose un cadre générique pour l'interopérabilité des réseaux. En fait, nous proposons une architecture satellitaire à base de WiMAX, DVB-RCS et IEEE 802.21 et nous décrivons aussi la procédure de handover WiMAX/DVB-RCS. Par ailleurs, nous améliorons les performances des réseaux WiMAX en utilisant un handover horizontal avec un mécanisme de réservation de ressources. Ensuite, le réseau WiMAX est intégré dans un système satellite DVB-RCS afin d'étudier les performances de cette convergence avec une réservation de ressources. Les résultats obtenus montrent que les mécanismes de réservation améliorent les performances. Afin de permettre au trafic de passer d'un réseau à l'autre en garantissant une qualité de service, une mise en correspondance de la qualité de service entre les réseaux WiMAX et DVB-RCS est proposée. En outre, nous proposons un mécanisme d'admission de connexion CAC dans le cadre de l'interconnexion WiMAX/DVB-RCS. Plusieurs stratégies sont prises en compte afin de permettre une coopérative efficace entre les deux systèmes.
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Hanslík, Radovan. "Odrazná plocha osobních automobilů." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2020. http://www.nusl.cz/ntk/nusl-412967.
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This diploma thesis is aimed at radar cross section of passenger cars. Basic scattering parameters of simple targets are described. Selected numeric methods used for computing radar cross section are discussed. Shape and size of simplified vehicle models is investigated. Simulations are verified by computing RCS of objects with well-known characteristics. Radar cross section of Skoda Octavia was simulated using selected numeric methods. Results of all performed simulations are shown in included graphs. Experimental measurment of radar cross section of a vehicle was performed so the measured data can be compared with the simulations.
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Kljajič, Marko. "Simulační studie robotické linky pro obsluhu obráběcího stroje a realizaci dokončovacích operací." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2020. http://www.nusl.cz/ntk/nusl-417547.
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The aim of the thesis is conceptual design of robotic workplace with its subsequent simulation. The current workplace for manufacturing and deburring parts for automotive industry is operated manually. The plan is overall automation and replacement of operators by robots. The thesis deals with the concept of layout of elements in the cell, and the procedure of their selection or design. Process simulation is performed in the Process Simulate software from Siemens. For the purposes of the work is used RCS module, which on the basis of dynamic conditions can calculate the cycle of production very close to the reality. The production cycle is compared to the current workplace. The work also deals with the economic evaluation of the proposed workplace.
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Grönberg, Christoffer. "Simulering och cykeltidsberäkning av automatiserad produktionslina med hjälp av Process Simulate." Thesis, Högskolan Väst, Institutionen för ingenjörsvetenskap, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:hv:diva-2806.
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Detta examensarbete har utförts i samarbete med Löfqvist Engineering i Örebro. Uppgiften har varit att utföra en simulering av en stor automatiserad produktionslina som ska användas vid tillverkning av avgassystem till lastbilar. Utifrån denna simulering skall exakta cykeltider för produktionen bestämmas. Dessa tider kan sedan användas av Löfqvist Engineering för att verifiera tidigare uppskattade tider. Arbetet inkluderar en litteraturstudie om Lean Production och hur det fungerar ihop med automation. Det finns även med lite bakgrundsinformation om Just In Time, olika filformat och robotsimulering i allmänhet för att ge en bättre överblick av ämnet. Programmet som har valts för att utföra simuleringen är Tecnomatix Process Simulate och den inbyggda Line Simulation modulen. Produktionslinan består av fyra hanteringsrobotar, 13 operatörsstationer och åtta identiska svetsceller. Cykeltider för produktionslinan har bestämts och resultatet blev 6 min 31 s, så det tar alltså lite drygt 6,5 minuter för produktionslinan att leverera en ny produkt. Cykeltiderna bestämdes genom att beräkna medelvärde på tiden det tog att framställa 10 stycken produkter då linan var full av material. I rapporten finns beskrivet hur arbetet för att komma fram till cykeltiderna har fortgått och hur simuleringsproblemen som uppstått under arbetets gång har lösts.This thesis has been carried out in collaboration with Löfqvist Engineering in Örebro. The task has been to perform a simulation of a large automation line, to be used in the manufacture of exhaust systems for trucks. Based on this simulation accurate cycle times for production are determined. These times can then be used by Löfqvist Engineering to verify the earlier estimated times. The work includes a literature review of Lean Production and how it works with automation. There is also some background information on Just In Time, different file formats and robot simulation in general for the reader to get a bit more background knowledge of the subject. The program that has been selected to perform the simulation is Tecnomatix Process Simulate and its built in Line Simulation module. The automation line consists of four handling robots, 13 operator stations and eight identical welding cells. Cycle times for the automation line have been determined and the result was 6 min 31s, for the automation line to complete one product. Cycle times were determined by calculating the average time to produce 10 pieces of products when the line was full of material. The report describes how the work for arriving at these cycle times have been performed and how simulation problems encountered during such operations have been resolved.
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Bui, Nicolas. "Méthode FDTD conforme et d’ordre (2,4) pour le calcul de SER large bande de cibles complexes." Thesis, Limoges, 2016. http://www.theses.fr/2016LIMO0118/document.
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L'évaluation précise de la surface équivalente radar (SER) large bande de cibles complexes et de grande dimension est réalisée par des méthodes numériques rigoureuses. Parmi celles-ci, la méthode des différences finies dans le domaine temporel (FDTD) est bien adaptée pour effectuer ce calcul de SER sur une large bande de fréquence et obtenir une signature temporelle de la cible. Le schéma de Yee, schéma FDTD historique pour la simulation de propagation d'ondes électromagnétiques en régime transitoire, souffre de deux points faibles cruciaux: la dispersion numérique imposant une finesse de maillage; et l'approximation de la géométrie curviligne par un maillage cartésien avec des marches d'escalier détériorant la qualité des résultats. Les schémas FDTD d'ordre supérieur en espace ont été investigués pour la réduction de l'effet de la dispersion numérique. Dans cette thèse, le schéma Conservative Modified FDTD(2,4) a été développé dont les performances, en précision et en ressources, sont très intéressantes pour le calcul de SER. Liés au problème de l'approximation de la géométrie curviligne, le traitement des bords de plaques métalliques reste une difficulté non résolue pour les schémas FDTD(2,4) à stencil élargi. Les techniques conformes sont des approches développées pour le schéma de Yee, lesquelles ont été étudiées pour les schémas FDTD(2,4) afin de prendre en compte correctement la géométrie curviligne. Nous proposons une nouvelle approche reposant sur le modèle des fils obliques pour la modélisation des éléments surfaciques métalliques. Des applications SER de cibles montrent que celle-ci est prometteuseRigorous numerical methods are used to compute an accurate wideband radar cross section (RCS) evaluation of large complex targets. Among these, finite differences in time domain method is appropriated for the wideband characteristic and also to obtain a transient responses of the target. The Yee scheme, known historically as an FDTD scheme for Maxwell equations, is hindered by two crucial weak points: numerical dispersion which imposes a high mesh resolution; and staircase approximation of curve geometry which deteriorates results quality. High-order space differential operator for FDTD schemes have been investigated to limit numerical dispersion errors. In this thesis, the Conservative Modified FDTD(2,4) scheme has been developed and its performance has shown very accurate results with reasonable workload for RCS computation. Relating to curve geometry modeling problem, metallic edges modeling is still an unsolved problem for FDTD(2,4) schemes with enlarged stencil. Conformal techniques have been developed for the Yee scheme and has been studied for FDTD(2,4) to accurately model curve geometry. We propose a new approach based on oblique thin wire model to model metallic surfaces. RCS computations of several targets have shown that this method is promising
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Arzur, Fabien. "Développement de simulateurs de cibles pour radars automobiles 77 GHz." Thesis, Brest, 2017. http://www.theses.fr/2017BRES0082.
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Le travail présenté dans ce manuscrit porte sur le développement d’un simulateur de cible (RTS) pour radars automobiles 77 GHz. Afin de proposer des véhicules toujours plus sûrs, les constructeurs automobiles développent des systèmes ADAS de plus en plus performants. On assiste aujourd’hui à la démocratisation des radars automobiles d’alerte à la collision et de régulation de distance. La généralisation de tels systèmes sur des véhicules de série va nécessiter le recours accru à des moyens de tests, chez les constructeurs et dans les centres de contrôle technique. Pour pouvoir tester et calibrer les radars, il est nécessaire d’utiliser des RTS. Ces appareils permettent de simuler les scénarios rencontrés par le radar, ceux-ci devenant plus complexes avec le développement des voitures autonomes. Une cible est définie par trois paramètres : une vitesse, une distance et une SER. Afin de répondre à des exigences drastiques, Autocruise développe ses propres RTS pour des bancs de test de production et de R&D. Ils doivent s’adapter à tout radar fonctionnant sur la bande 76 – 81 GHz, avec différentes modulations et une bande de fréquence supérieure à 800 MHz. Le système doit être à bas coût, de faibles dimensions et flexible pour être intégré dans différentes applications. Le principal verrou technologique est la réalisation d’une ligne à retard variable, capable de simuler des distances comprises entre 1 m et 250 m, avec une résolution de 0,2 m et permettre le contrôle de la SER. Un compromis devra être trouvé afin de répondre aux spécifications. L’étude a montré l’impossibilité de couvrir l’ensemble de la plage de distances avec une seule technologie. Une architecture hybride est indispensable. Une ligne à retard hybride reconfigurable large bande est présentéeThe work presented in this thesis concerns the development of an automotive radar target simulator for 77 GHz radar sensors. In order to continue offering safer vehicles, manufacturers develop more and more performant ADAS systems. We are witnessing a democratization of automotive radar sensors for adaptive cruise control and collision warning. The generalization of such systems on standard cars will require an increased use of test devices both at the manufacturers and in technical control centers. To test and calibrate radars, it is necessary to use Radar Target Simulators (RTS). These devices enable to simulate situations encountered by the radar. Furthermore, these scenarios are becoming increasingly complex with the arrival of autonomous vehicles. A target is defined by three parameters: distance, velocity and radar cross-section (RCS). In order to meet drastic requirements, ZF TRW Autocruise develops its own RTS for production test benches and R&D. RTS must adapt to all radars within a 76 – 81 GHz frequency band, with different modulations and a frequency bandwidth higher than 800 MHz. The system must present the advantages of being a low-cost system, with small dimensions and flexible to be integrated in different applications. The major blocking point is the design of a reconfigurable delay line, able to simulate distances between 1 m and 250 m with a resolution of 0.2 m on a large frequency band and also allowing control of RCS. A compromise will have to be found in order to meet the different specifications. The study showed the impossibility to cover the entire range of distances with one single technology. A hybrid architecture is necessary. A hybrid, tunable, wideband delay line is at study
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Mazzolo, Lisa-Marie. "Étude et développement d’un outil efficace de simulation pour l’évaluation de SER : Application à la détection d’objets enfouis à partir de plates-formes aéroportées." Electronic Thesis or Diss., Toulouse, ISAE, 2024. http://www.theses.fr/2024ESAE0047.
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La détection d'objets enfouis, qu'il s'agisse d'engins explosifs dans un contexte militaire ou de structures archéologiques dans un contexte civil, constitue une préoccupation majeure. En termes de télédétection radar, les systèmes aéroportés, comme le radar à synthèse d’ouverture (SAR), permettent une imagerie non destructive des sous-sols tout en offrant la possibilité d'explorer de vastes zones avec une distance de sécurité par rapport à celles-ci. Cependant, leur efficacité pour la détection d’objets enfouis dépend de nombreux facteurs, tels que les caractéristiques diélectriques du sol, qui affectent la profondeur de pénétration des ondes électromagnétiques, la nature des cibles, le type d'émetteur... Une étude préliminaire, permettant de prédire la réponse des cibles en fonction des caractéristiques des systèmes et de la scène, serait alors un outil précieux pour évaluer les capacités de détection avant d'engager des campagnes de mesures.Cette thèse s'inscrit dans ce contexte, en se concentrant sur la recherche, le développement et l'optimisation d'un outil de simulation numérique destiné à évaluer précisément la surface équivalente radar (SER) d'objets enfouis. L'approche proposée repose sur une stratégie d'hybridation de solveurs FVTD (Finite Volume Time Domain) appliquée à des maillages hybrides cartésiens / non-structurés dans l'optique d'optimiser les coûts de calcul. En particulier, ces maillages hybrides permettent une représentation conforme des géométries courbes et une discrétisation spatiale localement adaptée aux vitesses de propagation des ondes électromagnétiques dans les différents milieux de la scène de calcul. La procédure d'obtention de ces maillages, basée sur le découpage du domaine de calcul en sous-domaines est détaillée, et les solveurs FVTD utilisés sont décrits en soulignant les choix effectués pour optimiser leur efficacité. L'implémentation des modèles permettant une description représentative du sol, la prise en compte précise d'une source de type onde plane et le calcul de champs lointains en présence d'un milieu avec pertes, est également abordée. L'hybridation des solveurs FVTD via une stratégie multi-domaines / multi-méthodes est présentée en détail, en mettant l'accent sur l'architecture logicielle proposée et en précisant la stabilité de la solution hybride ainsi que les enjeux de l'hybridation. Enfin, une comparaison de résultats simulés avec des données expérimentales obtenues dans le cadre d'une campagne de mesures mise en œuvre pour cette thèse, fournit une première appréciation des performances de l'outil de simulation développé. Pour conclure, la thèse met en avant la possibilité d'utiliser cet outil pour étudier l'impact des paramètres de configuration des systèmes radar sur la SER d'objets enfouis pour des scénarios donnésThe detection of buried objects, whether explosive devices in a military context or archaeological structures in a civilian context, is a major concern. In radar remote sensing, airborne systems such as Synthetic Aperture Radar (SAR) allow non-destructive imaging of subsurface environments while offering the possibility of exploring large areas from a safe distance. However, their effectiveness in detecting buried objects depends on many factors, such as the dielectric properties of the soil, which affect the penetration depth of electromagnetic waves, the nature of targets, and the type of transmitter... A preliminary study that predicts target response based on system and scene characteristics would be a valuable tool for assessing detection capabilities before launching measurement campaigns.This thesis addresses such context by focusing on the research, development, and optimization of a numerical simulation tool designed to accurately evaluate the radar cross-section (RCS) of buried objects. The proposed approach is based on a hybridization strategy using Finite Volume Time Domain (FVTD) solvers applied to hybrid Cartesian/unstructured meshes to optimize computational costs. More specifically, these hybrid meshes allow for a conformal representation of curved geometries and spatial discretization adapted to the varying electromagnetic wave propagation speeds in different media. The procedure for generating these meshes, based on the subdivision of the computational domain into subdomains is detailed, and used FVTD solvers are described, highlighting the choices made to optimize their efficiency. The implementation of models for representative soil description, accurate handling of plane-wave sources, and far-field calculations in lossy media are also addressed. The hybridization of FVTD solvers through a multi-domain/multi-method strategy is presented in detail, emphasizing proposed software architecture, the stability of the hybrid solution, and the challenges of hybridization. Finally, a comparison of simulated results with experimental data obtained during a measurement campaign conducted for this thesis provides an initial assessment of the performance of developed simulation tool. In conclusion, this thesis highlights the potential of this tool in studying the impact of radar system configuration parameters on buried objects RCS in given scenarios
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Nishinari, Katsuhiro, Satoshi Kokubo, and Kazuhiro Yamamoto. "Simulation for pedestrian dynamics by real-coded cellular automata (RCA)." Elsevier, 2007. http://hdl.handle.net/2237/20045.
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MORGAT, ANNE. "Contribution a l'etude structurale des p21 ras. Simulations par dynamique moleculaire de la p21 ha ras." Paris 11, 1991. http://www.theses.fr/1991PA112159.
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La connaissance structurale approfondie des proteines ras (p21 ras) permet une meilleur comprehension des mecanismes reactionnels regulant leur activite biologique (fixation des nucleotides gdp, gtp et hydrolyse du gtp, en presence d'un ion mg ii). L'etude des complexes p21. Gppnp et p21. Gdp dans leur environnement cristallin, associee a une etude de leur surface moleculaire a montre des sites potentiels d'interactions avec d'autres macromolecules. Les proprietes dynamiques de la p21 ras complexee a une molecule de gppnp et un ion mg ii ont ete etudiees par dynamique moleculaire (programme discover). Cette simulation a apporte une meilleure connaissance des interactions entre la proteine et son ligand. L'effet de certaines mutations a pu etre evalue. Cette etude a permis d'emettre des hypotheses sur les sites d'interactions avec la proteine gap et le facteur d'echange, ainsi que sur leurs mecanismes d'action
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Klähn, Marco. "Untersuchung des intrinsischen GTPase-Mechanismus von Ras p21 mit Mitteln der Molekulardynamik-Simulation und QM/MM-Kraftfeld." [S.l.] : [s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=969939345.
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Silva, Alessandro Alves da. "Efeitos topográficos em espectros RBS." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-09042008-142058/.
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A medida da rugosidade de uma superfície costuma produzir resultados que dependem da metodologia empregada. A microscopia eletrônica de varredura, SEM, a microscopia de força atômica, AFM e a perfilometria são algumas das técnicas costumeiramente empregadas na caracterização de superfícies rugosas. Esse trabalho explora a e desenvolve o uso da espectrometria de retroespalhamento Rutherford, RBS, para medir e quantificar a rugosidade de uma superfície. Quatro diferentes amostras com rugosidade periódica e controlada (duas retangulares e duas senoidais) com razão de aspecto suficientemente grande que produzam efeitos mensuráveis por RBS, foram produzidas por interferometria óptica. Os espectros RBS experimentais foram convertidos em rugosidade rms e comparados com resultados de SEM e AFM. Medir rugosidade através de RBS permite inspecionar uma área (da ordem de alguns mm2) e profundidades muito maiores que as acessíveis por AFM, apesar de ainda limitados pela resolução em energia intrínseca da metodologia RBS.Measuring the roughness of a surface use to produce results which depend on the employed methodology. Scanning Electronic Microscopy, Atomic Force Microscopy, profilometry, are some of the techniques used to characterize surface roughness. This work explores and develops the use of Rutherford Backscattering Spectrometry to measure and quantify the roughness of a surface. Four different samples with controlled and periodic surface profiles (two rectangular waved, and two sinusoidal), with enough aspect ratio to, give measurable effects in an RBS analysis, were produced by optical interferometry to test and verify the proposed methodology. The experimental RBS spectra were converted into rms roughness and compared to SEM and AFM measurements. Measuring roughness by RBS enables one to inspect a much bigger area (of the order of some mm2) and with more depth resolution, than by using an AFM, yet still limited by the experimental intrinsic energy resolution of the RBS methodology.
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Dirks, Babette. "Simulation and Measurement of Wheel on Rail Fatigue and Wear." Doctoral thesis, KTH, Spårfordon, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-168023.
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The life of railway wheels and rails has been decreasing in recent years. This is mainly caused by more traffic and running at higher vehicle speed. A higher speed usually generates higher forces, unless compensated by improved track and vehicle designs, in the wheel-rail contact, resulting in more wear and rolling contact fatigue (RCF) damage to the wheels and rails. As recently as 15 years ago, RCF was not recognised as a serious problem. Nowadays it is a serious problem in many countries and ''artificial wear'' is being used to control the growth of cracks by preventive re-profiling and grinding of, respectively, the wheels and rails. This can be used because a competition exists between wear and surface initiated RCF: At a high wear rate, RCF does not have the opportunity to develop further. Initiated cracks are in this case worn off and will not be able to propagate deep beneath the surface of the rail or wheel. When wheel-rail damage in terms of wear and RCF can be predicted, measures can be taken to decrease it. For example, the combination of wheel and rail profiles, or the combination of vehicle and track, can be optimised to control the damage. Not only can this lead to lower maintenance costs, but also to a safer system since high potential risks can be detected in advance. This thesis describes the development of a wheel-rail life prediction tool with regard to both wear and surface-initiated RCF. The main goal of this PhD work was to develop such a tool where vehicle-track dynamics simulations are implemented. This way, many different wheel-rail contact conditions which a wheel or a rail will encounter in reality can be taken into account. The wear prediction part of the tool had already been successfully developed by others to be used in combination with multibody simulations. The crack prediction part, however, was more difficult to be used in combination with multibody simulations since crack propagation models are time-consuming. Therefore, more concessions had to be made in the crack propagation part of the tool, since time-consuming detailed modelling of the crack, for example in Finite Elements models, was not an option. The use of simple and fast, but less accurate, crack propagation models is the first step in the development of a wheel-rail life prediction model. Another goal of this work was to verify the wheel-rail prediction tool against measurements of profile and crack development. For this purpose, the wheel profiles of trains running on the Stockholm commuter network have been measured together with the crack development on these wheels. Three train units were selected and their wheels have been measured over a period of more than a year. The maximum running distance for these wheels was 230,000 km. A chosen fatigue model was calibrated against crack and wear measurements of rails to determine two unknown parameters. The verification of the prediction tool against the wheel measurements, however, showed that one of the calibrated parameters was not valid to predict RCF on wheels. It could be concluded that wheels experience relatively less RCF damage than rails. Once the two parameters were calibrated against the wheel measurements, the prediction tool showed promising results for predicting both wear and RCF and their trade-off. The predicted position of the damage on the tread of the wheel also agreed well with the position found in the measurements.QC 20150526
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Mondloch, Riley. "Characterization of agricultural floodplain scour using one-dimensional hydraulic simulation." Thesis, University of Iowa, 2014. https://ir.uiowa.edu/etd/1487.
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The Iowa Flood Center (IFC), a unit of The University of Iowa's IIHR - Hydroscience & Engineering, and the Iowa Department of Natural Resources are developing a statewide floodplain boundary dataset to provide information that is critical to proper flood mitigation planning. During flooding, soil loss from agricultural land, in addition to inundation, can have a substantial economic impact on an agricultural state like Iowa. The ability to identify areas with a high potential to experience scour during flooding could assist farmers and land owners in making better land management decisions. Currently, the IFC statewide floodplain mapping program is creating annual exceedance probability floodplain data for all Iowa streams. The effort described herein has developed methods to take advantage of this large dataset, applying uniform open channel flow theory to spatially characterize scour potential using custom tools created with GIS model builder. The results of this thesis are being used by the Iowa Natural Heritage Foundation (INHF) and the IFC to develop a program through which certified crop consultants can help farmers make more informed land management decisions based on risk of flood related soil loss.
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Dippolito, Mario. "Real scale simulation of ballistic test for soft armor." Diss., Kansas State University, 2017. http://hdl.handle.net/2097/36199.
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Doctor of PhilosophyDepartment of Mechanical and Nuclear Engineering
Youqi Wang
The strength of the fabric system is based on fiber strength and fabric mechanics. Modeling a fabric system accurately requires research into fiber behavior within the yarn and yarn behavior within the fabric. Limited computer resources require new approaches to yarn modeling and fabric modeling especially in regards to ballistic impact. The fabric is discontinuous. There are many factors which require modeling the physics in order to accurately simulate and design fabric systems. Weaving yarns into fabrics can introduce fiber level damages such as surface defects and crimps through sliding friction and bending and thus add variance to the tensile strength of the fibered yarn. A Weibull distribution is an often used method to develop a statistical model and is developed to calculate the strength of the yarn. It is necessary to carefully remove the fibers from the as woven fabric and use a standard ASTM single fiber tensile test to create a Weibull distribution of tensile strength. In general in Kevlar systems the edge radius for laboratory projectiles is much larger than the actual dimeter of the fiber; however, the yarn itself can be sheared, and this fibered yarn system requires modeling. There is no direct measurement of Kevlar fiber shear strength, so combined tensile-twist test data is used to develop equations to determined shear strength. DFMA is modeling software developed to create digital fabrics in a method that accurately models yarn shape with limited computer resources using a concept of a digital fiber. The digital fiber represents multiple real fibers, so it is necessary to use the digital yarn effective bending rigidity developed with numerical simulation of experimental results. Since the yarn is composed of hundreds to thousands of fibers, the physical yarn cannot be modeled in full scale fabrics. The yarn composed of digital fibers is structurally similar to real yarns and is capable of representing the real fabric mechanics. In the process of impact, within the relatively short time frame, the distribution of stress is mostly in principal yarns at a time when the event is considered complete through penetration or projectile rebound. The hybrid mesh method represents the small number of principal yarns with high density mesh and the rest of the fabric (the non-principal yarns) with coarse mesh. With hybrid mesh, the full scale simulation of actual fabrics is possible. The projectile geometry for real threats is variant depending on the types of projectiles in use (projectiles for maximum energy transfer to the target or projectiles for high shear). The laboratory projectiles are therefore variant in order to represent threats. In this research the RCC is the threat and two standard weights are modeled with local geometry. The local laboratory projectile geometry is controlled however it is bounded by a tolerance much larger than the Kevlar fibers studied here. It does act against the fibered yarn which will shear mechanically dependent on fiber to fiber interactions and possibly fiber shear strength.
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Davis, Mallory. "Numerical Simulation of Unsteady Hydrodynamics in the Lower Mississippi River." ScholarWorks@UNO, 2010. http://scholarworks.uno.edu/td/1126.
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Alterations along the Mississippi River, such as dams and levees, have greatly reduced the amount of freshwater and sediment that reaches the Louisiana coastal area. Several freshwater and sediment diversions have been proposed to combat the associated land loss problem. To aid in this restoration effort a 1-D numerical model was calibrated, validated, and used to predict the response of the river to certain stimuli, such as proposed diversions, channel closures, channel modifications, and relative sea level rise. This study utilized HEC-RAS 4.0, a 1-D mobile-bed numerical model, which was calibrated using a discharge hydrograph at Tarbert Landing and a stage hydrograph at the Gulf of Mexico, to calculate the hydrodynamics of the river. The model showed that RSLR will decrease the capacity of the Lower Mississippi River to carry bed material. The stage at Carrollton Gage is not significantly impacted by large scale diversions
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Abba, Omar Sabina. "Capability of CORDEX RCMs in simulating extreme rainfall events over South africa." Master's thesis, University of Cape Town, 2014. http://hdl.handle.net/11427/9103.
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Includes bibliographical references.In South Africa, extreme rainfall events often lead to widespread destruction, damage infrastructure, displace communities, strain water management and even destroy lives. Past studies have shown that reliable predictions of extreme rainfall events from regional climate models (RCMs) could help reduce the impact of these events. The present study evaluates the ability of nine RCMs in simulating extreme rainfall events over South Africa, focusing on the Western Cape (WC) and east coast (EC) areas. This study defines an extreme rainfall over a location as rainfall that is equal to or above the 95th percentile of the rainfall distribution at that location, and defines widespread extreme rainfall events (WEREs) over an area as events during which more than 50 of the grid-points in the area experience extreme rainfall. The 95th percentile threshold values were calculated over 11 years (1998-2008) of South Africa’s daily rainfall data from the nine RCMs (CCLM, REMO, PRECIS, CRCM5, ARPEGE, REGCM3, WRF, RACMO and RCA35), which participated in the Coordinated Regional Climate Downscaling Experiment (CORDEX) and used ERA-Interim (ERAINT) as their boundary forcing. The simulations were compared to two observation datasets (TRMM and GPCP), and to ERAINT rainfall data to understand whether these RCMs improve on the results from ERAINT. A self organizing map (SOM) was used to characterize WEREs identified in all the datasets into archetypal groups, and ERAINT data is used to describe the underlying circulations for each archetypal rainfall pattern. The number of WEREs mapped to each rainfall pattern for each dataset allows us to get an idea of whether certain RCMs are more likely to simulate certain rainfall patterns.
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Hossein, Nia Saeed. "An Investigation of the Iron-Ore Wheel Damages using Vehicle Dynamics Simulation." Licentiate thesis, KTH, Spårfordon, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-159733.
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Maintenance cost is one of the important issues in railway heavy haul operations. For the iron-ore company LKAB, these costs are mainly associated with the reprofiling and changing of the wheels of the locomotives and wagons. The main reason for the wheel damages is usually surface initiated rolling contact fatigue (RCF) on the wheels.The present work tries to enhance and improve the knowledge of the vehicle-track interaction of the Swedish iron-ore freight wagons and locomotives used at Malmbanan. The study is divided into two parts. Firstly, it is tried to get into the roots of RCF using the simulation model of the iron ore wagon (Paper A). Secondly, the study is focused on predicting wear and RCF on the locomotive wheels also via a dynamic simulation model (Paper B).In the first paper, some key issues of the dynamic modelling of the wagons with three piece bogies are first discussed and then parameter studies are carried out to find the most important reasons of wheel damages. These parameter studies include track design geometry, track irregularities, wheel-rail friction level, cant deficiency and track stiffness. The results show a significant effect of the friction level on the amount of RCF risk.As the locomotive wheel life is much shorter than that of the wagons, LKAB has decided to change the locomotive wheel profile. Two final wheel profiles are proposed; however, one had to be approved for the field tests. In the second paper, the long term evolution of the two profiles is compared via wear simulation analysis. Also, the RCF evolution on the wheel profiles as a function of running distance is discussed. The process is first carried out for the current locomotive wheel profiles and the results are compared with the measurements. Good agreement is achieved. Finally, one of the proposed profiles is suggested for the field test because of the mild wear and RCF propagation.QC 20150210
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Hossein, Nia Saeed. "On Heavy-Haul Wheel Damages using Vehicle Dynamics Simulation." Doctoral thesis, KTH, Spårfordon, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-220344.
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Maintenance cost is one of the important issues in railway heavy-haul operations. In most of the cases, these costs are majorly referring to reprofiling and changing the wheels of the locomotives and the wagons. The main reason of the wheel damages is usually severe wear and/or surface initiated rolling contact fatigue (RCF).This work tries to enhance and improve the knowledge of the wheel wear and RCF prediction models using dynamic simulations. While most of the contents of this study can be generalised to other operational networks, this study is focused on the locomotives and wagons of the Swedish iron-ore company LKAB. The trains are operating on the approximately 500 km long IORE line from Luleå to Narvik in the north of Sweden and Norway respectively.Firstly, a literature survey of dynamic modelling of the wagons with various three-piece bogie types is presented. Then, with concentrating on the standard three-piece bogies, parameter studies are carried out to find out what the most important reasons of wheel damages are. Moreover, the long-term stability of wheel profiles of the IORE wagons is analysed. This is done by visualising the wear and RCF evolution on the wheel profiles over 150,000km of simulated running distance.Most of the calculations for the wagons are repeated for the locomotives. However, traction and braking are also considered in the simulation model and their effects on wheel damages are briefly studied. To improve the accuracy of the wheel damage analysis, a newly developed algorithm called FaStrip is used to solve the tangential contact problem instead of FASTSIM. The damage prediction model developed in the thesis is used to study the effects of increasing axle load, correcting the track gauge, limiting the electro-dynamic braking and using a harder wheel material on the wheel life. Furthermore, a new method is developed to predict the running distance between two consecutive reprofilings due to severe surface initiated fatigue. The method is based on shakedown analysis and laboratory tests.Most of the research works in wear calculation are limited to two approaches known as wear number and Archard methods. The correlation between these two methods is studied. The possibility of using the relation between the two methods for the wear calculation process is investigated mainly to reduce the calculation time for wheel profile optimisation models.QC 20171219
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Harding, Charles P. "In Vitro Simulation of Microgravity Induced Muscle Loss Successfully Increases Expression of Key In Vivo Atrophy Markers." DigitalCommons@USU, 2019. https://digitalcommons.usu.edu/etd/7436.
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Muscle loss from lack of activity is a serious issue for immobilized patients on Earth and in human spaceflight, where the low gravity environment prevents normal muscle activity. Simulating muscle loss in cultured cells is an important step in understanding how this condition occurs. This work evaluates different means of simulating muscle loss and selects the one that most closely mimics the cellular responses seen in animals and humans.
To simulate the microgravity environment of spaceflight, mouse skeletal muscle cells were grown in a rotary cell culture system (RCCS). Growing the cells within a natural gelled substrate was compared against growing them on the surface of small plastic beads. Changes after culture under simulated microgravity were characterized by assessing proteins and genes known to change during muscle loss. The structure of the cells was also evaluated by microscopy.
The mouse skeletal muscle cells grown on plastic beads in the RCCS had significant changes in multiple key genes associated with muscle loss and demonstrated physical characteristics expected of mature tissue in live animals. This model is a valuable platform for exploring muscle loss mechanisms and testing new drugs.
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Hudec, Martin. "Klimatická změna a její vliv na vodohospodářské řešení zásobního objemu nádrže." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2018. http://www.nusl.cz/ntk/nusl-372277.
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The diploma thesis describes Climate Change and impacts of Climate Change on the development of the water management analyis of reservoir strorage capacity. The development of climate chang influence on reserviors storage capacity is presented until 2100. It also gives a detailed online downscaling description.
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Johnston, Michael. "Development of a molecular simulator and its application to the study of biomolecular dynamics." Doctoral thesis, Universitat Pompeu Fabra, 2009. http://hdl.handle.net/10803/7172.
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Aquesta tesi tracta de la creació d'un nou programari de codi obert i d'una interfície de programació (API) per realitzar simulacions (bio) moleculars, així com de a la seva aplicació posterior a problemes biològics. El nou programa, Adun, es focalitza en les àrees clau del càlcul d'energies lliures, el desenvolupament ràpid de programari i la productivitat d'alt rendiment. Mètodes com SCAAS, EVB i Born generalitzat han estat implementats per tal d'assolir el primer objectiu. La presencia d'aquestes tècniques, a m´es d'altres, mostra la velocitat de desenvolupament d'Adun. Totes les característiques s´on accessibles mitjanant una interfície gràfica d'usuari avançada que proveeix de noves capacitats, com el tractament de dades integrat o la compartició de dades i de càlculs distribuïts. La capacitat d'Adun de tractar problemes biològics és il·lustrada amb la investigació de la dinàmica de la proteïna Ras i el desenvolupament, implementació i demostració d'un nou mètode per a la determinació de camins de transició. A més, per tal de demostrar el potencial del programa Adun, aquests estudis també proporcionen una visió avançada sobre l'ús de la informació dinàmica en determinar la unció de les proteïnes. L'estat actual del programa i els resultats dels dos estudis és, doncs, discutit, i es donen indicacions dels objectius i direccions futurs. Finalment s'examina el paper dels científics computacionals com desenvolupadors d'eines, per a ells mateixos o per a tota la comunitat científica.This thesis deals with the creation of a new open-source program and API for biomolecular simulation and its subsequent application to biological problems. The program, Adun, focuses on the key areas of biological free-energy calculations, rapid development and highperformance productivity. Methods such as SCAAS, EVB and switched Generalised-Born have been implemented to realise the first aim. The presence of these techniques, along with a multitude of others, verifies Adun's rapid development potential. All these features are united by an advanced graphical user interface which provides novel capabilities such as inbuilt data management, and distributed datasharing and computation. Adun's ability to tackle biological problems is illustrated with an investigation of Ras dynamics and the development, implementation and testing of a novel method for determining transition paths. In addition to concretely demonstrating Adun's potential these studies also provide insight into the use of dynamic information in elucidating protein function. The current state of the program and the results of the two studies is discussed and indications of future aims and directions given. In addition the role of computational scientists as developers of tools, for themselves and the wider scientific community, is examined.
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Ssembatya, Martin. "PERFORMANCE EVALUATION OF A SOLAR COOLING SYSTEM IN UAE – RAS AL KHAIMAH BY BOTH EXPERIMENT AND SIMULATION." Thesis, Högskolan i Gävle, Akademin för teknik och miljö, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-14312.
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In United Arab Emirates (UAE), a huge proportion of electrical energy consumed in buildings is used to run air conditioning equipments. This is because UAE’s climate is characterized by very high ambient temperatures and high humidity, especially during summer periods. There is need to promote air conditioning systems that are run by renewable energy based power because of the environment threats and energy security negative issues associated with conventional fossil fuel – energy powered systems. The huge buildings’ cooling loads occur during periods of high solar insolation; this creates a huge potential of using solar powered cooling systems for air conditioning applications. However, the solar air conditioning systems still face a number of challenges in UAE which include; the availability of cheap electricity from fossil fuel resources and lack of government incentives to promote renewable energy resources. In order to understand the potential of applying solar cooling systems for air conditioning applications versus conventional systems, there was a need to experimentally and/or theoretically evaluate the performance of pilot solar cooling systems in UAE. In this project, the performance of a 10 TR solar cooling system in Ras Al Khaimah (RAK) Emirate of UAE was evaluated by both experiment and theoretical simulation. TRNSYS, a transient – systems simulation software that was developed by Solar Energy Laboratory – University of Winsconsin, was used for the purpose of the theoretical simulations of the system. The solar cooling absorption equipment used for this study is an R&D system that was developed by CSEM – uae in RAK for the purpose of assessing the potential of applying solar cooling systems in UAE. The solar cooling system is based on absorption chilling technology run by hot water produced by a field of evacuated tube solar collectors. Experimental results were compared with TRNSYS – theoretical simulations results and areas of possible improvements in the solar cooling system were recommended. Results of the study show that the solar cooling system runs with a COP in the range of 0.60 – 0.80, with an average COP of 0.70. It was also observed that the inlet cooling and hot water temperatures to the absorption chiller have a huge impact on the performance of the solar cooling system. A need to isolate the absorption chiller hot water circuit from the hot water stratified tank by incorporation of a heat exchanger between the chiller and the stratified tank was also identified. This will help to improve the degree of stratification during the operation of the solar cooling system. Theoretical performance evaluation of the system using a typical TMY2 weather data shows that the system can meet its cooling requirement for at least eight (8) months of the year. In conclusion, this study has indicated that solar cooling for air conditioning application in UAE has a huge potential. However, further research is necessary to enable improvement of the performance of solar cooling systems and to assess the possibility of commercialization of such systems.
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Pérez, Ancelmo Clodomiro Alcides. "Propuesta de implementación de un sistema de gestión de mantenimiento centrado en la confiabilidad para la industria farmacéutica." Bachelor's thesis, Universidad Peruana de Ciencias Aplicadas (UPC), 2018. http://hdl.handle.net/10757/625963.
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La siguiente propuesta de implementación está formada por tres capítulos en el primero se está considerando el marco teórico investigado de fuentes con revistas indexadas y respaldado por autores especialistas en los temas de confiabilidad, mantenibilidad definición, evolución, técnica, aplicación y tipos de mantenimiento.
En el segundo capítulo la situación y diagnostico actual de la empresa, identificación del activo más relevante y el impacto económico que genera.
En el tercer capítulo se muestra la propuesta de la implementación con respecto al diagnóstico que se realizó en los capítulos anteriores.
En el cuarto capítulo se muestra la simulación del proceso actual del activo, así como la aplicación de la metodología del RCM, en el cual podemos evaluar la viabilidad de dicha implementación.
Finalmente, las conclusiones y recomendaciones.The following implementation proposal consists of three chapters. In the first one is considering the theoretical framework researched from sources with indexes journals and supported by specialist authors in terms of reliability, maintainability, definition, evolution, technique, application and types of maintenance. The second chapter is about the situation and current diagnosis of the company, identification of the most relevant asset and the economic impact it generates. The third chapter shows the proposal of the implementation with respect to the diagnosis that was made in the previous chapter. The fourth chapter shows the simulation of the current asset process, as well as the application of the RCM methodology, in which we can evaluate the feasibility of such implementation. Finally, the conclusions and recommendations.
Tesis
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Mahmud, Sadab. "Development and Simulation of Maximum Power Point Tracking (MPPT) Controller with Ripple Correlation Control (RCC) for Deep Space Spacecraft." University of Toledo / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1588686169167826.
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Peyroux, Elodie. "Remédiation des troubles de la cognition sociale dans la schizophrénie et les troubles apparentés : le programme RC2S : études de cas uniques." Thesis, Lyon 2, 2014. http://www.theses.fr/2014LYO20124/document.
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Les difficultés à interagir dans le monde social et à s’y adapter sont une plainte centrale des personnes souffrant de troubles psychiatriques et notamment de schizophrénie ou de troubles apparentés. Ces difficultés, qui constituent un frein au processus de réhabilitation psychosociale, pourraient en partie être expliquées par un dysfonctionnement des processus regroupés sous le terme de cognition sociale. La cognition sociale est définie comme la capacité à construire des représentations sur soi-même et autrui, et sur les relations entre soi et les autres, ainsi qu’à utiliser ces représentations de manière flexible, afin de guider le comportement social ; et inclut des processus tels que le traitement des émotions, la théorie de l’esprit, le style attributionnel, la perception et les connaissances sociales. Des déficits concernant les différentes composantes de la cognition sociale ont été largement mis en évidence dans la schizophrénie et les troubles apparentés, et semblent par ailleurs avoir un lien fort avec les difficultés observées dans les domaines du fonctionnement social, mais également des relations privilégiées avec les processus neurocognitifs, même si ces deux composantes semblent relativement indépendantes. Afin de compenser ces troubles, de nombreuses prises en charge de remédiation cognitive ont été proposées ces dernières années. L’objectif de ce travail de thèse a été d’évaluer la possibilité d’améliorer les déficits touchant la sphère de la cognition sociale des personnes souffrant de troubles psychotiques à l’aide d’un outil de remédiation spécifiquement développé à cet effet, le programme RC2S. Etant donnée l’hétérogénéité des déficits touchant la sphère de la cognition sociale dans la schizophrénie, et l’importance fondamentale portée au transfert des compétences dans la vie quotidienne, RC2S a été développé comme une thérapie individualisée et flexible, qui permet aux patients de s’entraîner aux interactions sociales dans un environnement réaliste, et d’adapter la prise en charge aux difficultés spécifiques de la personne. Nous présenterons ici trois études basées sur la méthodologie du cas unique, mettant en évidence l’impact de cette thérapie sur les troubles de la cognition sociale de deux patients souffrant de schizophrénie et d’un patient présentant un trouble de la personnalité schizoïdeIn people with psychiatric disorders, particularly those suffering from schizophrenia and related illnesses, pronounced difficulties in social interactions and adaptation are a key manifestation. These disabilities, which are a serious impediment to psychosocial rehabilitation process, could be partly explained by impairments in processes grouped under the generic term of social cognition. Social cognition is defined as the ability to construct mental representations about others and oneself, and about one’s relationships to others, and to use these representations in a flexible way to guide social behavior. It includes abilities such as emotion processes, theory of mind (ToM), attributional style, and social perception and knowledge. In schizophrenia and related disorders, several components of social cognition are usually altered, and are strongly associated with functional outcome and independent but partly related to neurocognitive processes. The impact of several kinds of interventions and particularly of social cognitive remediation programs has been studied recently, and new strategies and programs in this line are currently being developed. The main objective of this doctoral thesis was to assess the feasibility of improving social cognition in people with psychotic disorders, using a cognitive remediation program specifically designed for this purpose, the RC2S program. Considering that the social cognitive deficits experienced by patients with schizophrenia are very diverse, and that the main objective of social cognitive remediation is to improve patient’s functioning in their social daily life, RC2S was developed as an individualized and flexible program, which allows patients to practice social interactions in a realistic environment, and to adapt therapy to the specificity of every patient’s profile. This manuscript present three single case studies, using specific methodology, to highlight the impact of this new therapy on social cognitive impairments of two people with schizophrenia and one patient with schizoid personality disorder
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Khan, Abdul Kareem. "Electrostaticanalisys the Ras active site." Doctoral thesis, Universitat Pompeu Fabra, 2009. http://hdl.handle.net/10803/7161.
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La preorganització electrostàtica del centre actiu s'ha postulat com el mecanisme genèric de l'acció dels enzims. Així, alguns residus "estratègics" es disposarien per catalitzar reaccions interaccionant en una forma més forta amb l'estat de transició, baixant d'aquesta manera el valor de l'energia dactivació g cat. S'ha proposat que aquesta preorientació electrostática s'hauria de poder mostrar analitzant l'estabilitat electrostàtica de residus individuals en el centre actiu.Ras es una proteïna essencial de senyalització i actúa com un interruptor cel.lular. Les característiques estructurals de Ras en el seu estat actiu (ON) són diferents de les que té a l'estat inactiu (OFF). En aquesta tesi es duu a terme una anàlisi exhaustiva de l'estabilitat dels residus del centre actiu deRas en l'estat actiu i inactiu.
The electrostatic preorganization of the active site has been put forward as the general framework of action of enzymes. Thus, enzymes would position "strategic" residues in such a way to be prepared to catalyze reactions by
interacting in a stronger way with the transition state, in this way decreasing the activation energy g cat for the catalytic process. It has been proposed that
such electrostatic preorientation should be shown by analyzing the electrostatic stability of individual residues in the active site.
Ras protein is an essential signaling molecule and functions as a switch in the
cell. The structural features of the Ras protein in its active state (ON state) are different than those in its inactive state (OFF state). In this thesis, an exhaustive analysis of the stability of residues in the active and inactive Ras active site is performed.
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Ghimire, Ekaraj. "Evaluation of One-Dimensional and Two-Dimensional HEC-RAS Models for Flood Travel Time Prediction and Damage Assessment Using HAZUS-MH: A Case Study of Grand River, Ohio." Youngstown State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1558558269011099.
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FRACCALVIERI, DOMENICO. "Comparison of protein dynamics: a new methodology based on self-organizing maps." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2011. http://hdl.handle.net/10281/19615.
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The deep relation between dynamics, in terms of both global and local flexibility, and function of proteins is now widely acknowledged. Flexibility is involved in protein binding to small molecules as well as in mechanisms involving domain motions and is also at the basis of signal transduction processes and allosteric interactions.
Computational methods, and in particular Molecular-Dynamics (MD) simulations, are widely applied in the investigation of a wide range of dynamic properties and processes that occur in the ps to μs timescale. By means of MD simulations a large ensemble of molecular structures can be generated to sample the accessible conformational space of a protein and identification of functionally relevant conformations is generally done by comparing and grouping the obtained conformations.
Data-mining techniques, like clustering, provide one means to group and analyse the information in the MD trajectory, but the results are often influenced by the type of algorithm and the choice of optimal parameters is often case dependent.
On the other hands, nowadays computer technology has simplified the complexity in analysing and visualizing scientific data. Within these techniques, the Self-Organizing Maps (SOMs) are an invaluable data mining tool.
In this thesis a novel strategy to analyse and compare conformational ensembles of protein domains was developed by using a two-level approach that combines SOMs and complete linkage clustering. First, the representation of the conformations extracted from the MD simulations were encoded as a proper input data for the SOM analysis. Second, the effects of the typical SOM parameters in the analysis of these data were studied by using an experimental design approach. Third the use of a rule to define the optimal number of clusters that best summarizes the information in the map was proposed.
Finally this new protocol was applied for the conformational and functional analysis of two study cases: a) a group of single-site mutants of the α-spectrin SH3 (Spc-SH3) domain and b) the bound and unbound states of a group of protein-protein complexes involving proteins of the RAS superfamily.
The results demonstrated the potential of this approach in the analysis of large ensembles of molecular conformations, i.e. the possibility of producing a topological mapping of the conformational space in a simple 2D visualisation, as well as of effectively highlighting differences in the conformational dynamics directly related to biological functions.
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Rodriguez, Caceres Adrian Rigoberto, and Fuchs Marysabel Valenzuela. "Propuesta de mejora del plan de gestión de mantenimiento basado en RCM y Lean Office en el proceso de inyección de polímeros." Bachelor's thesis, Universidad Peruana de Ciencias Aplicadas (UPC), 2020. http://hdl.handle.net/10757/655147.
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La propuesta es el diseño de una propuesta para mejorar la implementación del plan de gestión de mantenimiento en el proceso de moldeo por inyección de polímeros basado en la filosofía de las metodologías Lean Office y RCM. La aplicación se lleva a cabo en una empresa peruana de inyección de plástico donde se identificó el uso inadecuado del plan de Gestión de Mantenimiento, causado por la baja disponibilidad de repuestos y personal, el porcentaje de materia prima reprocesada y el deterioro de las Máquinas de moldeo. La importancia de resolver este problema es reducir la baja confiabilidad del equipo, la demora en la entrega de pedidos y la pérdida de producción. Los resultados esperados validado por la simulación de sistemas mostraron que la disponibilidad del personal aumentó a 83.07% y las paradas no planificadas de la máquina de inyección se redujeron en un 30%.This professional project for the title of Industrial Engineer, design of a proposal to improve the implementation of the maintenance management plan in the polymer injection molding process based on the philosophy of the Lean Office and RCM methodologies. The application is carried out in a Peruvian plastic injection company where the damaged use of the Maintenance Management plan, the risk due to the low availability of spare parts and personnel, the percentage of raw material reprocessed and the treatment of the Machines were identified Molding The importance of solving this problem is to reduce the low reliability of the equipment, the delay in the delivery of orders and the loss of production. The expected results validated by the simulation of controlled systems that the availability of the personnel had an 83.07% and the unplanned stops of the injection machine were reduced by 30%.
Trabajo de investigación
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Leduc, Alexandre. "Etude par la simulation et l'expérimentation de la production d'ions métalliques Calcium à l'aide d'une source d'ions du type Résonance Cyclotronique Electronique." Thesis, Normandie, 2019. http://www.theses.fr/2019NORMC239.
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Dans le cadre du projet SPIRAL2, la source d'ions à la résonance cyclotronique électronique (RCE) PHOENIX V3 (amélioration par rapport à la précédente version PHOENIX V2) a été développée afin d'augmenter la production d'ions avec un A/Q=3. La source vise principalement la production d'ions métalliques. Pour cela, des atomes métalliques sont sublimés dans un four avant d'être injectés dans la source d'ions. Lors de la production de tels faisceaux d'ions, la grande majorité des atomes se fixe au niveau de la paroi de la chambre à plasma et y reste. Ces pertes mènent à une faible efficacité globale d'ionisation (de l'ordre de la dizaine de pour cent).Un code hybride PIC (Particle In Cells) a été développé pour étudier la dynamique des particules chargées et reproduire les spectres d'ions en A/Q expérimentaux produits par la source d'ions PHOENIX V3. La simulation se concentre sur la propagation des ions en trois dimensions. A l'aide de plusieurs paramètres ajustables, la simulation reproduit la distribution des états de charges à la sortie de la source d'ions. Ce code a fourni des résultats encourageants.En parallèle de l'étude par simulation de la dynamique des particules dans le plasma, un ensemble de simulations reproduisant le fonctionnement du four pour atomes métalliques a été conçu. Les simulations permettent également l'analyse de la distribution angulaire des impulsions des particules quittant le creuset du four. Les distributions angulaires fournies par les simulations sont comparées à celles obtenues grâce à des mesures expérimentales.Une étude expérimentale a également été initiée afin de réduire le temps de collage des atomes métalliques injectés sur la chambre à plasma. Pour cela, un cylindre thermorégulé a été réalisé afin de favoriser la réévaporation des particules fixées. Il est ainsi possible d'augmenter l'efficacité globale d'ionisation d'au moins un facteur 2 et de mesurer l'augmentation de l'efficacité en fonction de la température de la paroiIn the framwork of the SPIRAL2 project, the Electron Cyclotron Resonance Ion Source PHOENIX V3 (upgrade of the previous source PHOENIX V2) has been developed to improve the production of highly charged ions with A/Q=3. The ion source mainly aims at the production of metal ion beams. For this, condensable atoms are sublimated into oven before being injected into the ion source. During the production of such ion beams, the major part of atoms travel towards the plasma chamber wall and remains there. Those losses lead to low global ionization efficiency (of the order of ten percent).An hybrid code PIC (Particle In Cells) was developed to study the dynamic of charged particles and to reproduce the experimental A/Q spectrum produced by the PHOENIX V3 ion source. The simulation focuses on the propagation of ions in 3D. Using several adjustable parameters, the simulation outcomes fit the charge state distribution at the exit of the ion source. This code has provided encouraging results.In parallel with the simulation study of particle dynamic in the plasma, a series of simulations have been run to reproduce the operation of an oven leading to the emission of metallic atoms. The outcomes of the simulations allow analysis of the angular distribution of the particles leaving the hot crucible. The angular distributions provided by the simulations are compared with those obtained through experimental measurements.An experimental study was also initiated to reduce the sticking time of the metal atoms on the plasma chamber. For this, a thermoregulated cylinder has been designed and realised to promote the re-evaporation of fixed paricles. It is thus possible to increase the global ionization efficiency by a factor 2 at least and to study the variation of the efficiency as a fonction of the cylinder temperature
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Lakshantha, Wickramaarachchige Jayampath. "Ion Beam Synthesis of Binary and Ternary Transition Metal Silicide Thin Films." Thesis, University of North Texas, 2016. https://digital.library.unt.edu/ark:/67531/metadc955104/.
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Among the well-known methods to form or modify the composition and physical properties of thin films, ion implantation has shown to be a very powerful technique. In particular, ion beam syntheses of binary iron silicide have been studied by several groups. Further, the interests in transition metal silicide systems are triggered by their potential use in advanced silicon based opto-electronic devices. In addition, ternary silicides have been by far less studied than their binary counterparts despite the fact that they have interesting magnetic and electronic properties. In this study, we investigate ion beam synthesis of Fe-Si binary structures and Fe-Co-Si ternary structures. This work involves fundamental investigation into development of a scalable synthesis process involving binary and ternary transitional metal silicide thin films and Nano-structures using low energy ion beams.
Binary structures were synthesized by implanting Fe- at 50 keV energy. Since ion implantation is a dynamic process, Dynamic simulation techniques were used in these studies to determine saturation fluences for ion implantation. Also, static and dynamic simulation results were compared with experimental results. The outcome of simulations and experimental results indicate, dynamic simulation codes are more suitable than static version of the TRIM to simulate high fluence, low energy and, heavy ion implantation processes. Furthermore, binary Fe-Si phase distribution was determined at different implantation fluences and annealing temperatures. A higher fluence implantation at 2.16×1017 atoms/cm2 and annealing at 500 oC showed three different Fe-Si phase formations (β-FeSi2, FeSi and Fe3Si) in substrate. Further, annealing the samples at 800 oC for 60 minutes converted the Fe3Si phase into FeSi2 and FeSi phases. As an extension, a second set of Fe- ion implantations was carried with the same parameters while the substrate was placed under an external magnetic field. External magnetic fields stimulate the formation of magnetic phase centers in the substrate. X-ray diffraction (XRD) results shows formation of ferromagnetic Fe3Si phase in the Si matrix after annealing at 500 oC for 60 minutes. In addition, X-ray photoelectron spectra (XPS) provide further evidence for ferromagnetic metallic behavior of Fe3Si in the substrate. Ternary Fe-Co-Si structures were synthesized by implanting Fe- & Co- into a Si (100) substrate at an energy of 50 keV at saturation fluences. Both Fe- & Co- co-implantation were performed under external magnetic fields to enhance magnetic phase formation. Fe(1-x)CoxSi B20-type cubic structure can be synthesized on Si(100) substrate with 0.4≤x≤0.55 concentration range using ion implantation under external magnetic field. Moreover, magnetic measurement indicates a possible magnetic phase transformation at ~50 K. Further, XPS results also provide evidence for metallic & ferromagnetic properties in the thin film structure
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Hilber, Patrik. "Component reliability importance indices for maintenance optimization of electrical networks." Licentiate thesis, Stockholm, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-274.
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Cojocaru, Vlad. "Molecular motions at the 5 stem-loop of U4 snRNA: Implications for U4/U6 snRNP assembly." Doctoral thesis, [S.l.] : [s.n.], 2005. http://webdoc.sub.gwdg.de/diss/2005/cojocaru.
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Hilber, Patrik. "Maintenance optimization for power distribution systems." Doctoral thesis, Stockholm : Electrical Engineering, Elektrotekniska system, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4686.
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Wattanasoontorn, Voravika. "Serious games for health and medicine. A cardiopulmonary resuscitation (CPR) case study." Doctoral thesis, Universitat de Girona, 2013. http://hdl.handle.net/10803/128270.
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Serious games are video games designed to provide specific expertise, knowledge and skills to the player, going beyond pure entertainment. In this thesis we present a classification of serious games for health and medicine that have been proposed in the last decade. We propose LISSA a serious game designed to teach the cardiopulmonar resuscitation protocol (RCP). In the context of LISSA, we study the visual realism of 3D serious games and their elements, evaluating photorealistic and non-photorealistic effects and camera position in first and third person. In addition, we study the physical realism to improve the interaction between game and player. We propose a new technique based on Kinect able to reproduce the key factors of the CPR protocol. Finally, we evaluate LISSA in a real scenarioEls anomenats jocs seriosos (de l’anglès serious games), són videojocs dissenyats per donar una experiència específica, coneixements i habilitats al jugador, és a dir van més enllà de l’entreteniment pur. En aquesta tesi presentarem una classificació dels jocs seriosos de l’àmbit mèdic i de la salut que s’han proposat en aquesta darrera dècada. Proposarem LISSA, un joc seriós dissenyat per ensenyar el protocol de reanimació cardiopulmonar (RCP). En el context del LISSA, estudiarem el realisme visual dels jocs seriosos 3D i els seus elements, avaluarem els efectes fotorealistes i no-fotorealistes i la posició de la càmera en primera i tercera persona. A més, estudiarem el realisme físic per tal de millorar la interacció entre el joc i el jugador. Proposarem una nova tècnica basada en Kinect capaç de reproduir factors clau del protocol RCP. Finalment, avaluarem LISSA en un escenari real
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Ben, Ammar Amira. "Approche cross-layer pour la minimisation d’énergie dans les réseaux de capteurs sans fil." Thesis, Paris, CNAM, 2018. http://www.theses.fr/2018CNAM1191/document.
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Les réseaux de capteurs sans fil (RCSF) sont des réseaux ad hoc généralement constitués d’entités autonomes miniaturisées appelés noeuds capteurs pouvant communiquer entre eux par liaison radio. Les RCSF ont suscité beaucoup d’engouement dans la recherche scientifique en raison notamment des nouveaux problèmes de routage sous forte contrainte de durée de vie du réseau et de faibles capacités des noeuds.Ce type de réseau diffère des réseaux filaires par ses caractéristiques et limitations qui ont motivé le développement d’une nouvelle approche de conception cross-layer ignorant certains paradigmes de l’approche classique permettant l’échange mutuel d’informations même entre couches non adjacentes. Cette approche qui n’est pas encore standardisée, a démontré son intérêt à travers plusieurs travaux visant un meilleur compromis entre consommation d’énergie et une certaine qualité de service.Nos contributions peuvent être classées en deux catégories suivant la stratégie de routage à savoir le routage ad-hoc et le routage suivant la technique de clustering.Dans la première partie, nous proposons une architecture cross-layer, modulaire, adaptable et extensible nommée XL-AODV (cross layer AODV) basée sur l'échange du SNR (Signal-to-Noise-Ratio) entre la couche réseau et la couche physique qui a été modélisée par la distribution K. Nous évaluons sous le simulateur NS2 les performances de notre approche XL-AODV. Une analyse comparative avec AODV, a montré pour différentes configurations de réseaux, l’efficacité de notre proposition en termes de gains énergétiques et de latence de bout en bout.Pour la deuxième partie, nous proposons une première approche XL-LEACH qui constitue une amélioration de la version originale de LEACH, en l'adaptant aux réseaux de capteurs denses et à grande échelle tout en tenant compte des caractéristiques de la couche physique modélisée par la distribution K. Dans une troisième partie, nous introduisons une amélioration de XL-LEACH par l'approche dite, XL-CLEACH (XL Cooperative LEACH) en intégrant la communication coopérative au niveau MAC. Nous avons prouvé par une étude analytique qui a été validée par les simulations, le gain apporté en termes de consommation d’énergie, de la durée de vie du réseau et du TES (Taux d'Erreur Symbol). Les architectures XL-LEACH et XL-CLEACH ont été implémentées sous MATLABWireless sensor networks (WSN) can be defined as an ad hoc network consisting of miniaturized autonomous entities, called sensor nodes which communicate with each other over a radio link. WSNs is a research topic which has gained a lot of interest due, in particular, to new routing problems under low node capacity and high network lifetime constraints.WSNs differ from wired networks in their characteristics and limitations which have motivated the development of a new cross-layer design that ignores certain paradigms of the classical approach allowing the mutual exchange of information even between non-adjacent layers. This approach, which is not yet standardized, has gained a lot of attention through several works aiming to energy consumption minimization under a required QoS (Quality of Service).In this thesis, our contributions can be classified are twofold according to the considered routing strategy namely the ad-hoc routing and clustering based routing.In the first part, we propose a new adaptable and extensible cross-layer design called XL-AODV (Cross Layer AODV) based on the exchange of the SNR (Signal-to-Noise-Ratio) between the network and the physical layer which has been modelled by the K distribution.We evaluate under the NS2 simulator, the performance of XL-AODV. A comparative analysis with AODV, showed for different network configurations, the efficiency of our proposition in terms of energy saving and end-to-end latency.In the second part, we propose an XL-LEACH approach which is an improvement of the original version of LEACH by its adapting to dense and large scale sensor networks. We have also taken into account the characteristics of the physical layer modelled by the K distribution.In a third part, XL-CLEACH (XL Cooperative LEACH) approach is introduced to improve XL-LEACH by integrating the cooperative communication at the MAC layer.We have proved through an analytical study and validated by simulations, the gain in terms of energy consumption, network lifetime and SER (Symbol Error Rate). The XL-LEACH and XL-CLEACH architecture were implemented under MATLAB
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Ben, Ammar Amira. "Approche cross-layer pour la minimisation d’énergie dans les réseaux de capteurs sans fil." Electronic Thesis or Diss., Paris, CNAM, 2018. http://www.theses.fr/2018CNAM1191.
Full textAbstract:
Les réseaux de capteurs sans fil (RCSF) sont des réseaux ad hoc généralement constitués d’entités autonomes miniaturisées appelés noeuds capteurs pouvant communiquer entre eux par liaison radio. Les RCSF ont suscité beaucoup d’engouement dans la recherche scientifique en raison notamment des nouveaux problèmes de routage sous forte contrainte de durée de vie du réseau et de faibles capacités des noeuds.Ce type de réseau diffère des réseaux filaires par ses caractéristiques et limitations qui ont motivé le développement d’une nouvelle approche de conception cross-layer ignorant certains paradigmes de l’approche classique permettant l’échange mutuel d’informations même entre couches non adjacentes. Cette approche qui n’est pas encore standardisée, a démontré son intérêt à travers plusieurs travaux visant un meilleur compromis entre consommation d’énergie et une certaine qualité de service.Nos contributions peuvent être classées en deux catégories suivant la stratégie de routage à savoir le routage ad-hoc et le routage suivant la technique de clustering.Dans la première partie, nous proposons une architecture cross-layer, modulaire, adaptable et extensible nommée XL-AODV (cross layer AODV) basée sur l'échange du SNR (Signal-to-Noise-Ratio) entre la couche réseau et la couche physique qui a été modélisée par la distribution K. Nous évaluons sous le simulateur NS2 les performances de notre approche XL-AODV. Une analyse comparative avec AODV, a montré pour différentes configurations de réseaux, l’efficacité de notre proposition en termes de gains énergétiques et de latence de bout en bout.Pour la deuxième partie, nous proposons une première approche XL-LEACH qui constitue une amélioration de la version originale de LEACH, en l'adaptant aux réseaux de capteurs denses et à grande échelle tout en tenant compte des caractéristiques de la couche physique modélisée par la distribution K. Dans une troisième partie, nous introduisons une amélioration de XL-LEACH par l'approche dite, XL-CLEACH (XL Cooperative LEACH) en intégrant la communication coopérative au niveau MAC. Nous avons prouvé par une étude analytique qui a été validée par les simulations, le gain apporté en termes de consommation d’énergie, de la durée de vie du réseau et du TES (Taux d'Erreur Symbol). Les architectures XL-LEACH et XL-CLEACH ont été implémentées sous MATLABWireless sensor networks (WSN) can be defined as an ad hoc network consisting of miniaturized autonomous entities, called sensor nodes which communicate with each other over a radio link. WSNs is a research topic which has gained a lot of interest due, in particular, to new routing problems under low node capacity and high network lifetime constraints.WSNs differ from wired networks in their characteristics and limitations which have motivated the development of a new cross-layer design that ignores certain paradigms of the classical approach allowing the mutual exchange of information even between non-adjacent layers. This approach, which is not yet standardized, has gained a lot of attention through several works aiming to energy consumption minimization under a required QoS (Quality of Service).In this thesis, our contributions can be classified are twofold according to the considered routing strategy namely the ad-hoc routing and clustering based routing.In the first part, we propose a new adaptable and extensible cross-layer design called XL-AODV (Cross Layer AODV) based on the exchange of the SNR (Signal-to-Noise-Ratio) between the network and the physical layer which has been modelled by the K distribution.We evaluate under the NS2 simulator, the performance of XL-AODV. A comparative analysis with AODV, showed for different network configurations, the efficiency of our proposition in terms of energy saving and end-to-end latency.In the second part, we propose an XL-LEACH approach which is an improvement of the original version of LEACH by its adapting to dense and large scale sensor networks. We have also taken into account the characteristics of the physical layer modelled by the K distribution.In a third part, XL-CLEACH (XL Cooperative LEACH) approach is introduced to improve XL-LEACH by integrating the cooperative communication at the MAC layer.We have proved through an analytical study and validated by simulations, the gain in terms of energy consumption, network lifetime and SER (Symbol Error Rate). The XL-LEACH and XL-CLEACH architecture were implemented under MATLAB
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Sun, Jie. "Intelligent flood adaptative contex-aware system." Thesis, Université Clermont Auvergne (2017-2020), 2017. http://www.theses.fr/2017CLFAC076/document.
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A l’avenir, l'agriculture et l'environnement vont pouvoir bénéficier de plus en plus de données hétérogènes collectées par des réseaux de capteurs sans fil (RCSF). Ces données alimentent généralement des outils d’aide à la décision (OAD). Dans cette thèse, nous nous intéressons spécifiquement aux systèmes sensibles et adaptatifs au contexte basés sur un RCSF et un OAD, dédiés au suivi de phénomènes naturels. Nous proposons ainsi une formalisation pour la conception et la mise en œuvre de ces systèmes. Le contexte considéré se compose de données issues du phénomène étudié mais également des capteurs sans fil (leur niveau d’énergie par exemple). Par l’utilisation des ontologies et de techniques de raisonnement, nous visons à maintenir le niveau de qualité de service (QdS) des données collectées (en accord avec le phénomène étudié) tant en préservant le fonctionnement du RCSF. Pour illustrer notre proposition, un cas d'utilisation complexe, l'étude des inondations dans un bassin hydrographique, est considéré. Cette thèse a produit un logiciel de simulation de ces systèmes qui intègre un système de simulation multi-agents (JADE) avec un moteur d’inférence à base de règles (Jess)In the future, agriculture and environment will rely on more and more heterogeneous data collected by wireless sensor networks (WSN). These data are generally used in decision support systems (DSS). In this dissertation, we focus on adaptive context-aware systems based on WSN and DSS, dedicated to the monitoring of natural phenomena. Thus, a formalization for the design and the deployment of these kinds of systems is proposed. The considered context is established using the data from the studied phenomenon but also from the wireless sensors (e.g., their energy level). By the use of ontologies and reasoning techniques, we aim to maintain the required quality of service (QoS) level of the collected data (according to the studied phenomenon) while preserving the resources of the WSN. To illustrate our proposal, a complex use case, the study of floods in a watershed, is described. During this PhD thesis, a simulator for context-aware systems which integrates a multi-agent system (JADE) and a rule engine (Jess) has been developed.Keywords: ontologies, rule-based inferences, formalization, heterogeneous data, sensors data streams integration, WSN, limited resources, DSS, adaptive context-aware systems, QoS, agriculture, environment
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Cimentada, Jorge. "Educational institutions and their effect on inequality: three papers on educational systems and inequality of achievement and opportunity." Doctoral thesis, Universitat Pompeu Fabra, 2019. http://hdl.handle.net/10803/667640.
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By placing particular attention to the socio-economic dimension, this thesis explores the role of three pillars of an educational system: decentralization, early education and curricular tracking. The first article focuses on an experiment in Mexico that aimed to increase parental empowerment in the school's decision-making. Results show that increased participation produced an increase in cognitive abilities, however, this was mediated by the SES of the student. The second article brings an international perspective by comparing the evolution of the achievement gap over time in 32 countries. The findings suggest that tracking and vocational enrollment are important explanatory mechanisms of the cross-country variability in achievement gaps. The third article studies whether early education is associated with adult outcomes but concentrating on a particularly vulnerable population in the United States: GED recipients. Results show that participation in early education is associated with greater odds of graduating high school over attaining a GED.Esta tesis explora el rol de tres pilares de un sistema educativo: descentralización, educación temprana y seguimiento curricular. El primer artículo estudia un experimento en México que tuvo como objetivo aumentar el empoderamiento de padres en la toma de decisiones en la escuela. Los resultados muestran que mayor participación de los padres aumentó las habilidades cognitivas de sus hijos. Sin embargo, esto fue mediado por el SES del estudiante. El segundo artículo compara la evolución de la brecha de logros en 32 países. Los hallazgos sugieren que el seguimiento curricular y los estudios vocacionales pueden ser mecanismos explicativos de la brecha. El tercer artículo estudia si la educación temprana está asociada con resultados positivos en la adultez en Estados Unidos. Los resultados muestran que la participación en educación temprana está asociado con mayores probabilidades de graduarse de la escuela secundaria en comparación con la obtención de un GED.
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Chuang, Kai-Chieh, and 莊凱傑. "The design and implementation of DVB-RCS satellite system over the NCTUns Network Simulator." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/41302046280408858395.
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Bakhsh, Anis. "Modeling and simulation of forced circulation evaporation crystallizer." Thesis, 2013. http://ethesis.nitrkl.ac.in/6617/1/M._Tech.(Res.)-610CH308.pdf.
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Crystallization is an effective process of forming a solid phase from solution and crystallizer is the equipment used for industrial crystallization operations. There has been a
lot of experimental research work carried out for understanding and improving crystallization operations in the past years, several aspects relating to the crystal growth, nucleation, breakage, type of crystallization process, design of crystallizer and scale up of crystallizers. It is difficult to analyze complex hydrodynamic behaviour in crystallizer by experiment. In last decade a good number of works has been carried out using CFD simulation for different types of crystallizers to study the flow dynamics and crystal formation. In present work flow behavior, solid suspension distribution, population density and mean crystal growth studies have been carried out for the forced circulation evaporation crystallizer (FC crystallizer) by CFD simulations using software package; Ansys Fluent 13. The FC crystallizer is a continuously operating mixed suspension mixed product removal (MSMPR) type crystallizer used in salt, sugar and pharmaceutical industries for crystal production. In the present work simulation has been carried out in isothermal and non-isothermal conditions to characterize the hydrodynamics and population balance model to explain the population density. 3D modified computational geometries have been used to observe the vigorous 3D multiphase flow by Eulerian model. The process of crystallization of NaCl from its solution has been used for simulation. NaCl solution and water vapor has been considered as the two phase liquid and gas. Water and solid particles (NaCl) as two phase has been used to see the crystal size distribution. For population density study all three phases: NaCl solution, NaCl crystals, and vapor has been considered. RNG k-ϵ model has been used for turbulent fluctuations of velocities in multiphase phase flow. The present work is carried out under varying conditions of flow rates and inlet positions. From the results it is observed that phase distribution, velocity profiles and pressure is changing with change in flow rates for isothermal and non-isothermal both conditions Increase in inlet height found to affect the vapor distribution. Flow rate and inlet position are affecting the suspension distribution in crystallizer. Better distribution of crystals is seen for higher flow rate of solution and for
inlet at higher position. Population density of large crystals and mean crystal size is found to increase with time.
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Wu, Huali. "Heat Transfer Simulation of Reactor Cavity Cooling System Experimental Facility using RELAP5-3D and Generation of View Factors using MCNP." Thesis, 2013. http://hdl.handle.net/1969.1/151265.
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As one of the most attractive reactor types, The High Temperature Gas-cooled Reactor (HTGR) is designed to be passively safe with the incorporation of Reactor Cavity Cooling System (RCCS). In this paper, a RELAP5-3D simulation model is set up based on the 1/16 scale experimental facility established by Texas A&M University. Also, RELAP5-3D input decks are modified to replicate the experiment procedures and the experimental results are compared with the simulation results. The results show there is a perfect match between experimental and simulation results.
Radiation heat transfer dominates in the heat transfer process of high temperature gas-cooled reactor due to its high operation temperature. According to experimental research done with the RCCS facility in Texas A&M University, radiation heat transfer takes up 80% of the total heat transferred to standing pipes. In radiation heat transfer, the important parameters are view factors between surfaces. However, because of the geometrical complexity in the experimental facility, it is hard to use the numerical method or analytical view factor formula to calculate view factors. In this project, MCNP based on the Monte Carlo method is used to generate view factors for RELAP5-3D input. MCNP is powerful in setting up complicated geometry, source definition and tally application. In the end, RCCS geometry is set up using MCNP and view factors are calculated.
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LIANG-TA, TU, and 凃良達. "A Simulation Study on Applying HEC-RAS Inundation Model in Guidan Stream Watershed." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/10115428853980945342.
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碩士國立屏東科技大學
水土保持系所
97
Taiwan locates in subtropical zone of meteorological condition and gets plenty of raining in monsoon and typhoon season，The mean annual precipitation reach 2510mm；Because of the unequal rainfall distribution in space and time and the steep slope of stream bed heavy storm usually cause serious damages both in human life and properties. Therefore, this research used the recorded data from rainfall station near Guidan stream and to estimate flood frequency analysis. The methodology adopted to estimate design peak flow rates for different return periods. The important findings of the study are stated as follows: 1.To compare the maximum rainfall in a single day and relations among rainfall intensity, duration and frequency during Typhoon KALMAEGI,it appears that the rainfall intensity exceed the 50-year rainfall return period. It would be the main reason caused the flood in Guidan region. 2.Because some area of stream channel is narrow, and the local farmer takes the river course situation to be serious, in addition has not equipped the Revetment protection or the Revetment protection is highly insufficient, the draining water cross section is unable to discharge runoff creates is flooded the circumstances to occur. 3.As the research result shows, the flood capacity at bridge and cross river structure of Guidan stream is resulting in drainage section not enough and backwater raise. Because the construction age is remote, the bridge already obsolete and the breakage and the watering cross section are mostly insufficient, is unable to discharge flows. The safety for the existing bridge has been more dangerous after Typhoon KALMAEGI and would be destroyed possibly.
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Sehoana, Kabelo Albert. "Simulation of natural circulation in an air-cooled Reactor Cavity Cooling System using Flownex / Kabelo Albert Sehoana." Thesis, 2014. http://hdl.handle.net/10394/15542.
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Nuclear reactors with improved safety concepts are currently being studied within the nuclear engineering community, with a focus on passive safety features. One of these reactor concepts is the Very High Temperature gas-cooled Reactor (VHTR) of which the Reactor Cavity Cooling Systems (RCCS) is seen as an integral and crucial part of the passive safety concept. Considerable validation and development of the necessary software tools is required to perform analysis and designs of these future reactor concepts.
The primary objective of this study is to establish a methodology for the creation of an integrated system level process model of a typical air-cooled RCCS in Flownex®, and to illustrate its applicability by simulating different scenarios that illustrate the operational characteristics of such a system. For this purpose, the existing RCCS conceptual design that is being studied by the KAERI was used as the case study.
As a start, selected case studies were performed to verify that the Flownex® models were set up correctly to perform natural circulation flows, both in steady and transient conditions, and with radiation, convection and conduction taking part. These are the major typical physical phenomena in the RCCS. The models were compared with EES (Engineering Equation Solver) models of the same geometries and specifications. There was a good agreement between Flownex® and EES model results.
After this verification, a simulation model of the integrated RCCS system was developed. The Flownex® models were applied to model selected possible operational scenarios. The major observations from the results are that:
- The RCCS carries with it enough heat to the ambient such that the concrete wall temperature is maintained below the benchmark value of 65°C for the different boundary conditions imposed.
- The RCCS maintains its functionality even with three quarters of the risers blocked or in the event that there is a break in one of the chimney pipes.MIng (Nuclear Engineering), North-West University, Potchefstroom Campus, 2015
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Stites, Edward Cooper. "Network analysis of oncogenic Ras activation /." 2008. http://wwwlib.umi.com/dissertations/fullcit/3289596.
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Chiao-YaChang and 張喬亞. "Integration of HEC-RAS and FLO-2D Models for Inundation Simulation in Dianbao River Basin." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/34929623894047107875.
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碩士國立成功大學
水利及海洋工程學系碩博士班
101
This study aims to integrate HEC-RAS and FLO-2D models for inundation simulation and assess their performances. The study area focuses on the regional drainage of Dianbao River in Kaohsiung whose low-relief catchment is easily affected by tide level and is hard to drain overland flow properly. In the event that large mountain runoff or storm surge resulting from intense rainfall happens, the catchment often suffers from serious inundation due to the rise of external floodwater and the blocked drainage of internal floodwater. Thus, by analyzing the inundation depth and extent of downstream flat region, a reliable inundation model can act as an early warning system and future reference for the lowland responsing to typhoon events. This study integrated Triangular Unit Hydrograph, hydraulic model and inundation model to analyze the flood conditions in the inundation areas. To solve the exchange problem between channel and overland flow, this study compared different water levels simulated by HEC-RAS and FLO-2D to obtain the water level hydrograph. By introducing water level hydrograph into FLO-2D, we calculated the inundation extent and depth. Various spatial resolutions were investigated in this study to assess the effect on inundation simulations. In consideration of simulation time and its accuracy, our result indicated that 60m × 60m grid resolution has the best optimal simulation result. The result of the comparison of two simulated inundation maps between FLO-2D model and physiographic inundation-drainage model is that the integration of HEC-RAS and FLO-2D has reasonable inundation extent and simulation results Typhoon Kalmaegi in 2008, Morakot in 2010 and Fanapi in 2011 are further chosen as validation events. According to the comparison between the simulated inundation map and the field survey, we could find out that the integration of HEC-RAS and FLO-2D can reasonably simulate the inundation extent and depth in this area.