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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
491

Essays in Spatial Econometrics: Estimation, Specification Test and the Bootstrap

Jin, Fei 09 August 2013 (has links)
No description available.
492

Adapting modeling environments to domain specific interactions

da Silva de Sousa, Vasco Nuno 12 1900 (has links)
Software tools are being used by experts in a variety of domains. There are numerous software modeling environments tailored to a specific domain expertise. However, there is no consistent approach to generically synthesize a product line of such modeling environments that also take into account the user interaction and experience adapted to the domain. The focus of my thesis is the proposal of a solution to explicitly model user interfaces and interaction of modeling environments so that they can be tailored to the habits and preferences of domain experts. We extend current model-driven engineering techniques that synthesize graphical modeling environments to also take interaction models into account. The formal semantics of our language framework is based on statecharts. We define a development process for generating such modeling environments to maximize reuse through a novel statechart refinement technique. / Les outils logiciels sont utilisés par des experts dans une variété de domaines. Il existe de nombreux environnements de modélisation logicielle adaptés á une expertise spécifique. Cependant, il n’existe pas d’approche cohérente pour synthétiser génériquement une ligne de produits de tels environnements de modélisation qui prennent également en compte l’interaction et l’expérience utilisateur adaptées au domaine. L’objectif de ma thése est la proposition d’une solution pour modéliser explicitement les interfaces utilisateur et l’interaction des environnements de modélisation afin qu’ils puissent étre adaptés aux habitudes et aux préférences des experts du domaine. Nous étendons les techniques d’ingénierie actuelles pilotées par un modéle qui synthétisent des environnements de modélisation graphique pour prendre également en compte les modèles d’interaction. La sémantique formelle de notre cadre linguistique est basée sur des statecharts. Nous définissons un processus de développement pour générer de tels environnements de modélisation afin de maximiser la réutilisation à travers une nouveau technique de raffinement de statecharts.
493

Time-Resolved Adaptive Finite Element Simulations for Building Aerodynamics : A proof of concept on minimal computational resources / Tidsupplösta adaptiva finita elementsimuleringar för byggnadsaerodynamik : Ett koncepttest med minimala beräkningsresurser

van Beers, Linde January 2021 (has links)
The effect of building geometry on the wind environment of cities is such that it can cause problems like wind danger, discomfort and poor ventilation of airborne pollutants. Computational fluid dynamics (CFD) can play a role in assessing changes in wind environment caused by building projects before realisation at little cost. However, the current state-of-the-art methods, RANS and LES, force a steep trade-off between accuracy and computational cost, and neither method is truly predictive. Time-resolved adaptive direct finite element simulation (DFS) is a method for CFD that is predictive and automatically optimises the mesh for a goal quantity, making it both efficient and accurate. In this thesis, DFS was implemented in FEniCS and used on basic validation cases to provide a proof of concept for the use of this method in the building aerodynamics, on resources freely available to anyone. The results show that the method is accurate to within 10% of the validation data with respect to the goal quantity. Visually, the expected flow features are clearly identifiable. DFS was successfully applied to a relatively complicated building geometry, with a total computation time of about 120 core-hours. We conclude that DFS has significant potential as a method for evaluating urban wind environments. Furthermore, because of its ease of use and lack of parameters, DFS can play an important role in helping architects, designers and students understand the effect of urban geometries on the wind environment. This report provides a basis for further research on DFS for building aerodynamics, as validation on more diverse urban geometries is still necessary. / Effekten av byggnaders form och geometri är så viktig att den kan ge problem för ventilation av t.ex. föroreningar, för energieffektivitet, och för vindfaror med t.ex. hög vindhastihet som kan vara farligt eller skapa obehag. Beräkningsströmningsdynamik (CFD) kan ha en roll i bedömningen av byggnadsprojekt i ett tidigt skede till liten kostnad. Dock är de etablerade och ledande metodikerna, RANS och LES, inte prediktiva och tvingar fram en kompromiss mellan beräkningskosnad och noggrannhet. Vår metodik “Time-resolved adaptive direct finite element simulation” (DFS) är en metod för CFD som är prediktiv och automatiskt optimerar beräkningsnätet (och därmed beräkningskostnaden) för en given målkvantitet, som ger både effektivitet och noggrannhet. I denna avhandling implementerades DFS i FEniCS och användes i grundläggande valideringsfall för att ge ett proof of conceptför användning av denna metod i byggnadsaerodynamik, på resurser som är fritt tillgängliga för alla. Resultaten visar att metoden är korrekt inom 10% av valideringsdata med avseende på målkvantiteten. Visuellt är de förväntade flödesfunktionerna tydligt identifierbara. DFS applicerades framgångsrikt på en relativt komplicerad byggnadsgeometri med en total beräkningstid på cirka 120 kärntimmar, vilket är en försumbar kostnad. Vi drar slutsatsen att DFS har en betydande potential som metod för utvärdering av stadsvindmiljöer. Dessutom, på grund av dess användarvänlighet och frihet från parametrar, kan DFS spela en viktig roll för att hjälpa arkitekter, designers och studenter att förstå effekterna av stadsgeometrier på vindmiljön. Denna rapport ger en grund för vidare forskning om DFS för aerodynamik, eftersom validering av mer olika stadsgeometrier fortfarande är nödvändig.
494

Grain Structure Modification in Additively Manufactured Inconel 718 Using in situUltrasonic Vibration

McNees, Nathaniel Gregory January 2022 (has links)
No description available.
495

Two and Three-Dimensional Finite Element Analysis of Plasticity-Induced Fatigue Crack Closure: A Comprehensive Parametric Study

Solanki, Kiran N 13 December 2002 (has links)
Finite element analyses are frequently used to model growing fatigue cracks and the associated plasticity-induced crack closure. Two-dimensional, elastic-perfectly plastic finite element analyses of middle-crack tension (M(T)), bend (SEB), and compact tension (C(T)) geometries were conducted to study fatigue crack closure and to calculate the crack opening values under plane-strain and plane-stress conditions. The loading was selected to give the same maximum stress intensity factor in both geometries, and thus similar initial forward plastic zone sizes. Mesh refinement studies were performed on all geometries with various element types. For the C(T) geometry, negligible crack opening loads under plane-strain conditions were observed. In contrast, for the M(T) specimen, the plane-strain crack opening stresses were found to be significantly larger. This difference was shown to be a consequence of in-plane constraint. Under plane-stress conditions, it was found that the in-plane constraint has negligible effect, such that the opening values are approximately the same for the C(T), SEB, and M(T) specimens. Next, the crack opening values of the C(T), SEB and M(T) specimens were compared under various stress levels and load ratios. The effect of a highly refined mesh on crack opening values was noted and significantly lower crack opening values than those reported in literature were found. A new methodology is presented to calculate crack opening values in planar geometries using the crack surface nodal force distribution under minimum loading as determined from finite element analyses. The calculated crack opening values are compared with values obtained using finite element analysis and more conventional crack opening assessment methodologies. It is shown that the new method is independent of loading increment, integration method (normal and reduced integration), and crack opening assessment location. The compared opening values were in good agreement with strip-yield models.
496

Studies of Halide Perovskites CsPbX<sub>3</sub>, RbPbX<sub>3</sub> (X=Cl<sup>-</sup>, Br<sup>-</sup>, I<sup>-</sup>), and Their Solid Solutions

Linaburg, Matthew Ronald January 2015 (has links)
No description available.
497

Vers un paradigme transformationnel dans le développement orienté objet

Khriss, Ismail 05 1900 (has links)
Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal. / Plusieurs modèles de maintenance exigent que les changements soient faits et documentés dans les spécifications des besoins et soient par la suite propagés vers le code source à travers les modè­les d'analyse et de conception. Ces modèles supposent donc un haut niveau de traçabilité comme facteur clé de maintenabilité. Cette traçabilité ne peut être obtenue sans une approche transforma­tionnelle au développement des logiciels. Cette thèse a pour objectif de fournir une approche transformationnelle pour supporter l' ingénie­rie des besoins à l'aide des scénarios et pour appliquer les patrons de conception au moyen d'algorithmes et de processus. Le langage unifié de modélisation (Unified Modeling Language, UML) a été adopté comme notation de modélisation. Dans le support de l'ingénierie des besoins, nous proposons, premièrement, un algorithme incrémental pour la synthèse des spécifications dynamiques à partir des scénarios. Cet algorithme prend comme entrée un ensemble de diagrammes de collaboration d'UML et produit en sortie les diagrammes d'états-transitions d'UML de tous les objets collaborant dans les scénarios d'entrée. En outre cet algorithme permet la vérification de la cohérence et de la complétude des scénarios. Deuxièmement, un autre algorithme est conçu pour la génération d'un prototype de l'interface usager (IU) à partir de la spécification des scénarios. Les scénarios sont acquis sous forme de dia­grammes de collaboration enrichis par des informations de l'IU. Ce prototype de l'IU peut être exécuté par un constructeur d'IU ce qui permet non seulement la validation des scénarios avec les utilisateurs mais aussi sa personnalisation et son raffinement éventuel. L'application automatique des patrons de conception est réalisée par une nouvelle approche pour le raffinement successif des modèles (en format UML) statiques et dynamiques de conception. Ces raffinements successifs sont basés sur des schémas de raffinement. Un schéma de raffinement est composé de deux compartiments. Le premier compartiment décrit le modèle abstrait de con­ception, et le deuxième compartiment montre le modèle détaillé correspondant après l'application d'un patron de conception. Nous proposons aussi un catalogue de schémas de micro-raffinement qui permettent non seulement de décrire un schéma de raffinement mais aussi de prouver sa vali­dité. / Several maintenance models suggest that changes be done and docurnented in the requirernents specification and subsequently propagated through the analysis and design models to the source code. These models require all a high level of traceability. Such traceability can only be obtained by a transformational approach to software development. The objective of this thesis is to provide a transformational approach for supporting requirernents engineering based on scenarios and for applying design patterns by rneans of algorithms and pro­cesses. The Unified Modeling Language (UML) was adopted as the notational framework. For supporting requirements engineering, we propose first an incrernental algorithm for synthesiz­ing behavioral specifications frorn scenarios. This algorithrn generates from a given set of UML collaboration diagrams the UML statechart diagrams of all the abjects involved. Moreover, this algorithm allows for the verification of consistency and cornpleteness of the input scenarios. Secondly, another algorithm is designed to generate a user interface (UI) prototype from scenar­ios. Scenarios are acquired in the form of UML collaboration diagrams, which are enriched with UI information. This UI prototype can be executed in a UI builder environment for the validation of the scenarios by the users, for customization, and for further refinernent. The automatic application of design patterns is achieved by a new approach to the stepwise refine­ment of static and dynamic design models represented as UML diagrams. Refinement is based on refinement schemas which are cornposed of two compartments. The first compartrnent describes the abstract design model, whereas the second compartment shows the corresponding detailed rnodel after application of one design pattern. We also propose a catalogue of smaller transforma­tions called micro-refinement schernas. These micro-refinernent schernas are proven to be correct and can be used to compose correct refinernent schemas.
498

Design, synthesis and characterization of small-pore zeolites for industrial environmental applications

Boruntea, Cristian-Renato 21 April 2020 (has links)
Tesis por compendio / [ES] El Proyecto de investigación aquí descrito se estructura en dos partes. La primera parte se centra en la investigación fundamental con el objetivo de crear un protocolo para la síntesis de zeolitas. La segunda parte se refiere al diseño, síntesis y caracterización de nuevas zeolitas, particularmente utiles para aplicaciones DeNOx,, pero también podría ser útil para aplicaciones MTO. La investigación fundamental sugiere un Nuevo modelo de preparación de zeolitas utilizando otras zeolitas como simiente. Este proceso se llama transformación zeolita-zeolita o también conversión interzeolita. El alto rendimiento obtenido, la rápida cristalización y la mejor utilización y rendimiento de los materiales de partida se han tenido en cuenta para mejorar el proceso en base a un proyecto de doctorado financiado por una empresa. Este método se ha ilustrado utilizando varias zeolitas como semilla, entre otras FAU y CHA, para la preparación de las dos zeolitas objetivo: AEI y AFX. En la segunda parte, la investigación se centra en el diseño de nuevas zeolitas de poro medio. Se han seleccionado tres zeolitas hipotéticas de una base de datos de 933611 estructuras. Esta selección se ha realizado utilizando descriptores específicamente diseñados en base a la aplicabilidad de estas zeolitas en procesos DeNOx zeolitas. A continuación se han buscado los agentes directores de estructura (ADE) más apropiados, con la ayuda de métodos computacionales, algunos de los cuales se han sintetizado posteriormente. El uso de dichos ADE en el gel de síntesis ha permitido la obtención de una zeolita cuya topología (ERI) ha sido identificada mediante análisis por PXRD, y cuya morfología y tamaño de cristal (particularmente pequeño) la hacen muy adecuada para su uso como catalizador en algunos procesos. El trabajo de síntesis también reveló la aparición de una nueva zeolita de alta densidad, llamada 'paracelsio-K'. Este nuevo material se ha obtenido al explorar el espacio de fases que cristalizan al utilizar 1-methyl-DABCO como ADE. La síntesis de esta zeolita tiene un especial interés porque el ADE no se incorpora en los canales de la zeolita, pero más bien influyendo en la nucleación y cristalización. La caracterización reveló que la composición del material es próxima al mineral microcline, estructuralmente cercano al paracelsio, ambos feldespatos. A diferencia de los feldespatos el paracelsio-K contiene moléculas de agua en su interior (1 molécula por cavidad) y puede describirse como el material más simple de la familia de las zeolitas que contiene cadenas del tipo 'doble-cigüeñal'. Utilizando los elementos topológicos correspondientes a esta estructura es posible generar estructuras zeolíticas ya conocidas, como GIS, APC, MER, PHI, SIV y algunas otras zeolitas hipotéticas. / [CA] El Projecte d'investigació aquí descrit s'estructura en dos parts. La primera part se centra en la investigació fonamental amb l'objectiu de crear un protocol per a la síntesis de zeolites. La segona part es refereix al disseny, síntesis i caracterització de noves zeolites, particularment útils per a aplicacions DeNOx , però també podria ser útil per a aplicacions MTO. La investigació fonamental suggereix un nou model de preparació de zeolites utilitzant altres zeolites com a llavor. Aquest procés s'anomena transformació zeolita-zeolita o també conversió interzeolita. L'alt rendiment obtingut, la ràpida cristal·lització i la millor utilització i rendiment dels materials de partida s'han tingut en compte per millorar el procés en base a un projecte de doctorat finançat per una empresa. Aquest mètode s'ha il·lustrat utilitzant diverses zeolites com a llavor, entre altres FAU i CHA, per a la preparació de les dues zeolites objectiu: AEI i AFX. A la segona part, la investigació se centra en el disseny de noves zeolites de porus mitjà. S'han seleccionat tres zeolites hipotètiques d'una base de dades de 933.611 estructures. Aquesta selecció s'ha realitzat utilitzant descriptors específicament dissenyats sobre la base de l'aplicabilitat d'aquestes zeolites en processos DeNOx zeolites. A continuació s'han buscat els agents directors d'estructura (ADE) més apropiats, amb l'ajuda de mètodes computacionals, alguns dels quals s'han sintetitzat posteriorment. L'ús d'aquests ADE al gel de síntesi ha permès l'obtenció d'una zeolita la topologia (ERI) ha estat identificada mitjançant anàlisi per PXRD, i la morfologia i mida de vidre (particularment petit) la fan molt adequada per al seu ús com a catalitzador en alguns processos. El treball de síntesi també va revelar l'aparició d'una nova zeolita d'alta densitat, anomenada 'paracelsio-K'. Aquest nou material s'ha obtingut a explorar l'espai de fases que cristal·litzen en utilitzar 1-methyl-DABCO com ADE. La síntesi d'aquesta zeolita té un especial interès perquè el ADE no s'incorpora en els canals de la zeolita, però més aviat influint en la nucleació i cristal·lització. La caracterització va revelar que la composició del material és propera al mineral microcline, estructuralment proper al paracelsio, tots dos feldspats. A diferència dels feldspats el paracelsio-K conté molècules d'aigua al seu interior (1 molècula per cavitat) i pot descriure com el material més simple de la família de les zeolites que conté cadenes del tipus 'doble-cigonyal'. Utilitzant els elements topològics corresponents a aquesta estructura és possible generar estructures zeolítiques ja conegudes, com GIS, APC, MER, PHI, SIV i algunes altres zeolites hipotètiques. / [EN] The research project described herein is structured in two parts. The first part is focused on the fundamental research with the aim of creating a toolbox for zeolite preparation. The second part deal with the design, synthesis and characterization of novel zeolites particular useful for DeNOx applications, but could be also useful for MTO applications. The fundamental research is addressing a novel approach of preparing zeolites by using other zeolites as raw materials. This process is known as zeolite-to-zeolite transformation or interzeolite conversion. The high yield obtained, fast crystallization time and the better utilization of the raw materials (e.g. parent zeolite, organic structure directing agent (OSDA)), are important benefits of interzeolite conversion technic, which answer the objectives formulated for an industrial PhD project. The method has been exemplified by using various raw materials as parent zeolites, such as FAU and CHA for the preparation of two target small pore zeolites AEI and AFX. In the second part the focus has been on the design of novel small pore zeolites. Three hypothetical frameworks have been selected by narrowing down a database containing 933611 structures. The selection has been performed by using the general descriptors for the state-of-the-art DeNOx zeolites (e.g. CHA). This was followed by finding suitable OSDAs for the selected frameworks, by using computational methods. The usage of the theoretically predicted OSDAs in synthesis gels made possible the synthesis of a novel high-silica zeolite. PXRD analysis, revealed that the zeolite has the ERI framework topology. The obtained material has a distinct particle morphology and smaller crystallites, which are key parameters for various catalytic processes. The synthesis work revealed also a novel dense zeolite, named K-paracelsian. The new material has been obtained while exploring the phase space using 1-methyl-DABCO as OSDA. The synthesis of this zeolite is especially interesting in the sense that the OSDA is not being incorporated into the zeolite channels, but rather influencing the nucleation and crystallization. Further characterization revealed a material compositionally closely related to the mineral microcline and structurally closely related to the mineral paracelsian, both of which are feldspars. In contrast to the feldspars, K-paracelsian contains intrazeolitic water corresponding to one molecule per cage and can be described as the simplest endmember of a family of dense double-crankshaft zeolite topologies. By applying the identified building principle, a number of known zeolite frameworks (e.g. GIS, APC, MER, PHI, SIV) and hypothetical zeolite topologies can be constructed. / The authors thank Haldor Topsoe A/S and Innovation Fund Denmark for financial support under the Industrial PhD programme (Case no. 1355-0174B). We thank MINECO of Spain for funding (SEV-2016- 0683 and RTI2018-101033-B-100) and ASIC-UPV for the use of computational facilities. We also thank Prof. M. M. J. Treacy for assistance with the Database of Prospective Zeolite Structures. / Boruntea, C. (2020). Design, synthesis and characterization of small-pore zeolites for industrial environmental applications [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/141094 / Compendio
499

Quantifying Trust in Wearable Medical Devices

Thomas, Mini January 2024 (has links)
This thesis explores a methodology to quantify trust in wearable medical devices (WMD) by addressing two main challenges: identifying key factors influencing trust and developing a formal framework for precise trust quantification under uncertainty. The work empirically validates trust factors and uses a Bayesian network to quantify trust. The thesis further employs a data-driven approach to estimate Bayesian parameters, facilitating query-based inference and validating the trust model with real and synthetic datasets, culminating in a customizable parameterized trust evaluation prototype for WMD. / Advances in sensor and digital communication technologies have revolutionized the capabilities of wearable medical device (WMD) to monitor patients’ health remotely, raising growing concerns about trust in these devices. There is a need to quantify trust in WMD for their continued acceptance and adoption by different users. Quantifying trust in WMD poses two significant challenges due to their subjective and stochastic nature. The first challenge is identifying the factors that influence trust in WMD, and the second is developing a formal framework for precise quantification of trust while taking into account the uncertainty and variability of trust factors. This thesis proposes a methodology to quantify trust in WMD, addressing these challenges. In this thesis, first, we devise a method to empirically validate dominant factors that influence the trustworthiness of WMD from the perspective of device users. We identified the users’ awareness of trust factors reported in the literature and additional user concerns influencing their trust. These factors are stepping stones for defining the specifications and quantification of trust in WMD. Second, we develop a probabilistic graph using Bayesian network to quantify trust in WMD. Using the Bayesian network, the stochastic nature of trust is viewed in terms of probabilities as subjective degrees of belief by a set of random variables in the domain. We define each random variable in the network by the trust factors that are identified from the literature and validated by our empirical study. We construct the trust structure as an acyclic-directed graph to represent the relationship between the variables compactly and transparently. We set the inter-node relationships, using the goal refinement technique, by refining a high-level goal of trustworthiness to lower-level goals that can be objectively implemented as measurable factors. Third, to learn and estimate the parameters of the Bayesian network, we need access to the probabilities of all nodes, as assuming a uniform Gaussian distribution or using values based on expert opinions may not fully represent the complexities of the factors influencing trust. We propose a data-driven approach to generate priors and estimate Bayesian parameters, in which we use data collected from WMD for all the measurable factors (nodes) to generate priors. We use non-functional requirement engineering techniques to quantify the impacts between the node relationships in the Bayesian network. We design propagation rules to aggregate the quantified relationships within the nodes of the network. This approach facilitates the computation of conditional probability distributions and enables query-based inference on any node, including the high-level trust node, based on the given evidence. The results of this thesis are evaluated through several experimental validations. The factors influencing trust in WMD are empirically validated by an extensive survey of 187 potential users. The learnability, and generalizability of the proposed trust network are validated with a real dataset collected from three users of WMD in two conditions, performing predefined activities and performing regular daily activities. To extend the variability of conditions, we generated an extensive and representative synthetic dataset and validated the trust network accordingly. Finally, to test the practicality of our approach, we implemented a user-configurable, parameterized prototype that allows users of WMD to construct a customizable trust network and effectively compare the trustworthiness of different devices. The prototype enables the healthcare industry to adapt and adopt this method to evaluate the trustworthiness of WMD for their own specific use cases. / Thesis / Doctor of Philosophy (PhD) / In this thesis, two challenges in quantifying trust in wearable medical devices, are addressed. The first challenge is the identification of factors influencing trust which are inherently subjective and vary widely among users. To address this challenge, we conducted an extensive survey to identify and validate the trust factors. These factors are stepping stones for defining the specifications and quantifying trust in wearable medical devices. The second challenge is to develop a precise method for quantification of trust while taking into account the uncertainty and variability of trust factors. We constructed a Bayesian network, that captures the complexities of trust as probabilities of the trust factors (identified from the survey) and developed a data-driven approach to estimate the parameters of the Bayesian network to compute the measure of trust. The findings of this thesis are empirically and experimentally validated across multiple use cases, incorporating real and synthetic data, various testing conditions, and diverse Bayesian network configurations. Additionally, we developed a customizable, parameterized prototype that empowers users and healthcare providers to effectively assess and compare the trustworthiness of different wearable medical devices.
500

Numerische und experimentelle Untersuchung der fluiddynamischen Eigenschaften von Strahlströmungen in begrenzten Räumen

Ringleb, Ansgar 03 April 2018 (has links)
In der vorliegenden Arbeit wurden Strömungen räumlich begrenzter Strahlen untersucht. Zum einen wurde die Ausströmung eines runden Strahls in ein Rohr betrachtet, der sog. begrenzte Strahl. Zum anderen wurde die Ausströmung von 7 hexagonal angeordneten runden Strahlen in ein Rohr betrachtet, das sog. hexagonale Strahlbündel. Die Motivation zur vorliegenden Arbeit ergab sich aus der Entwicklung von Durchflussmessgeräten, die als Bypassapparaturen ausgeführt sind und stromabwärts des Staudruckkörpers ein Strömungsgebiet mit begrenzten Strahlen aufweisen. Dafür wurden mit Hilfe der Ähnlichkeitstheorie die zugrundeliegenden Kennzahlen bestimmt. Besonderes Augenmerk lag auf der Charakterisierung der instationären bzw. turbulenten Strömungseigenschaften für Reynolds-Zahlen zwischen 1.000 und 20.000. Es wurden die selbstähnlichen Eigenschaften der Strömungen untersucht, wobei sich insbesondere für den begrenzten Strahl wichtige Erkenntnisse ergaben. Für das hexagonale Strahlbündel wurden mit Hilfe der numerischen Strömungssimulation die grundlegenden Eigenschaften des Strömungsfeldes untersucht. Dabei weisen die Geometriekennzahlen einen dominierenden Einfluss auf. So konnten in Abhängigkeit zum Durchmesserverhältnis und Strahlabstand drei Strömungsformen identifiziert und experimentell mittels Laser-Doppler Anemometrie nachgewiesen werden. Eine wesentliche Fragestellung bestand in der Anwendung der numerischen Strömungssimulation, des RANS-Ansatzes und des SST-Turbulenzmodells. Dazu wurde die Anpassung der Modellkoeffizienten untersucht, wobei für den begrenzten Strahl ein allgemein gültiger Satz gefunden wurde. / In the present work flows of spatially limited radiation were investigated. On the one hand, the outflow of a round jet into a pipe was considered, the so-called confined jet. On the other hand, the outflow of 7 hexagonal arranged round jets into a pipe was con-sidered, the so-called hexagonal jet array. The motivation for the present work arose from the development of flowmeters which are designed as bypass apparatures that have a jet array flow downstream of the dynamic pressure body. For this purpose the underlying similarity parameters were determined. Special attention was paid to the cha-racterization of transient and turbulent flow properties for Reynolds numbers between 1,000 and 20,000. The self-similar properties of the flows were investigated with im-portant findings in particular for the confined jet. For the hexagonal jet array the basic properties of the flow field were investigated by using computational fluid dynamics. The geometric similarity parameters have a dominant influence. Thus, depending on the di-ameter ratio and jet distance ratio, three flow patterns could be identified and experimen-tally detected by the use of laser Doppler anemometry. An important question was the application of the computational fluid dynamic method, the RANS approach and the SST turbulence model. For this purpose a generally valid set of model coefficients was found for the confined jet flow.

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