Дисертації з теми "Moment scheme of the finite element"
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Wang, Hanyang. "Moment method analysis of slotted waveguide antennas incorporating finite element method." Thesis, Heriot-Watt University, 1994. http://hdl.handle.net/10399/1350.
Повний текст джерелаГребенюк, Сергій Миколайович, Сергей Николаевич Гребенюк та Sergii M. Grebeniuk. "Напружено-деформований стан просторових конструкцій на основі гомогенізації волокнистих композитів". Thesis, Запорізький національний технічний університет, 2016. http://eir.zntu.edu.ua/handle/123456789/1212.
Повний текст джерелаUK: На основі аналітичних розв’язків методом представницького об’ємного елемента отримані співвідношення для ефективних пружних сталих композита з транстропними матрицею і волокном. Побудована матриця жорсткості паралелепіпедного скінченного елемента на основі моментної схеми, яка враховує особливості просторової орієнтації волокон. Описано підхід до розв’язку геометрично нелінійної задачі за допомогою модифікованого метода Ньютона-Канторовича. Запропоновані підходи використано при створенні пакету прикладних програм. Визначено напружено-деформований стан гумовокордних віброізоляторів та автомобільної шини, а також головного обтічника ракетоносія. EN: In terms of analytical solutions by use of the presentation box unit the correlations for the effective elastic constants of the composite with the trans-tropic matrix and fiber are first obtained. It is constructed the stiffness matrix of the parallelepiped finite element on the basis of the moment scheme taking into account specific of the spatial orientation of the fibers. The approach to the solution of the geometrically non-linear problem with the help of modified Newton-Kantorovich method is described. On the basis of the approaches proposed it is developed package of the applied programs. The stress-strained state of the rubber-cord vibration isolators and the car tyre as well as the main carrier rocket fairing is determined. RU: На основе аналитических решений методом представительного объемного элемента получены соотношения для эффективных упругих постоянных композита с транстропными матрицей и волокном. Построена матрица жесткости параллелепипедного конечного элемента на основе моментной схемы, которая учитывает особенности пространственной ориентации волокон. Описан подход к решению геометрически нелинейной задачи с помощью модифицированного метода Ньютона-Канторовича. Предложенные подходы использованы при создании пакета прикладных программ. Определено напряженно-деформированное состояние резинокордных виброизоляторов и автомобильной шины, а также головного обтекателя ракетоносителя.
梁少江 and Siu-kong Leung. "Analysis of shear/core wall structures using a linear moment beam-typeelement." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1996. http://hub.hku.hk/bib/B31213352.
Повний текст джерелаWilson, Kevin E. "A Finite Element Investigation of Non-Orthogonal Moment Connections in Steel Construction." University of Cincinnati / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1445609099.
Повний текст джерелаLeung, Siu-kong. "Analysis of shear/core wall structures using a linear moment beam-type element /." Hong Kong : University of Hong Kong, 1996. http://sunzi.lib.hku.hk/hkuto/record.jsp?B18155376.
Повний текст джерелаTremblay, Frédéric 1970. "Introduction of a second-moment closure turbulence model in a finite element formulation." Thesis, McGill University, 1997. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=27258.
Повний текст джерелаTremblay, Frédéric. "Introduction of a second-moment closure turbulence model in a finite element formulation." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ29632.pdf.
Повний текст джерелаSchroeder, John M. "Moment-Rotation Curves for Shear Tab Connections Using Finite Element Modeling and Experimental Data." University of Cincinnati / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1337954722.
Повний текст джерелаProvidas, Efthimios. "On the geometrically nonlinear constant moment triangle (with a note on drilling rotations)." Thesis, Brunel University, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.277518.
Повний текст джерелаRuffley, Daniel J. "A Finite Element Approach for Modeling Bolted Top-and-Seat Angle Components and Moment Connections." University of Cincinnati / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1304448809.
Повний текст джерелаOlmez, Harun Deniz. "A Numerical Study On Special Truss Moment Frames." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/12611322/index.pdf.
Повний текст джерелаYazdani, Alireza. "A novel bubble function scheme for the finite element solution of engineering flow problems." Thesis, Loughborough University, 2007. https://dspace.lboro.ac.uk/2134/34029.
Повний текст джерелаDominisse, Kyle Richard. "Strength and Stiffness of Weak-Axis Moment End-Plate Connections." Thesis, Virginia Tech, 2004. http://hdl.handle.net/10919/46194.
Повний текст джерелаFinite element models of the tests were created with the commercial software SAP2000. A simplified modeling procedure was developed to overcome the contact problems between the end-plates and column web, and between the bolts and holes in the end-plates and web. The simplified modeling procedure accurately predicted the experimental elastic stiffness, in the form of column web rotations, of the connections.
Yield line theory was used to investigate the plastic strength of the column web. Several yield line patterns were examined. Analytical plastic moment strengths were very conservative when compared to the observed behavior of the column web.
The experimental stiffness of the test with the concrete slab confining the top extension of the end-plate was compared to the stiffness of a similar test without a slab. The slab increased the elastic stiffness of the connection; however, after the concrete began cracking and crushing around the connection, the stiffness was greatly decreased.
Master of Science
Mays, Timothy Wayne. "Application of the Finite Element Method to the Seismic Design and Analysis of Large Moment End-Plate Connections." Diss., Virginia Tech, 2000. http://hdl.handle.net/10919/11245.
Повний текст джерелаPh. D.
Lan, Shuang Wen. "Stochastic finite element analysis of structures with elementary stiffness matrix decomposition method and exponential polynomial moment method." Thesis, University of Macau, 2010. http://umaclib3.umac.mo/record=b2148241.
Повний текст джерелаChelikani, Abhinand. "Simulation of a backrest moment test for an automotive front seat using nonlinear contact finite element analysis." Connect to this title online, 2007. http://etd.lib.clemson.edu/documents/1202409952/.
Повний текст джерелаLink, Gerhard. "A finite element scheme for fluid-solid-acoustics interactions and its application to human phonation." Bamberg Meisenbach, 2008. http://d-nb.info/99357047X/04.
Повний текст джерелаShemirani, Faramarz. "The development of a generalised finite element scheme for heat transfer and fluid flow analysis." Thesis, Nottingham Trent University, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.294102.
Повний текст джерелаAbbas, Ebrahim K. "A Low Cycle Fatigue Testing Framework for Evaluating the Effect of Artifacts on the Seismic Behavior of Moment Frames." Diss., Virginia Tech, 2015. http://hdl.handle.net/10919/64256.
Повний текст джерелаPh. D.
Marais, Neilen. "Efficient high-order time domain finite element methods in electromagnetics." Thesis, Stellenbosch : University of Stellenbosch, 2009. http://hdl.handle.net/10019.1/1499.
Повний текст джерелаThe Finite Element Method (FEM) as applied to Computational Electromagnetics (CEM), can beused to solve a large class of Electromagnetics problems with high accuracy and good computational efficiency. For solving wide-band problems time domain solutions are often preferred; while time domain FEM methods are feasible, the Finite Difference Time Domain (FDTD) method is more commonly applied. The FDTD is popular both for its efficiency and its simplicity. The efficiency of the FDTD stems from the fact that it is both explicit (i.e. no matrices need to be solved) and second order accurate in both time and space. The FDTD has limitations when dealing with certain geometrical shapes and when electrically large structures are analysed. The former limitation is caused by stair-casing in the geometrical modelling, the latter by accumulated dispersion error throughout the mesh. The FEM can be seen as a general mathematical framework describing families of concrete numerical method implementations; in fact the FDTD can be described as a particular FETD (Finite Element Time Domain) method. To date the most commonly described FETD CEM methods make use of unstructured, conforming meshes and implicit time stepping schemes. Such meshes deal well with complex geometries while implicit time stepping is required for practical numerical stability. Compared to the FDTD, these methods have the advantages of computational efficiency when dealing with complex geometries and the conceptually straight forward extension to higher orders of accuracy. On the downside, they are much more complicated to implement and less computationally efficient when dealing with regular geometries. The FDTD and implicit FETD have been combined in an implicit/explicit hybrid. By using the implicit FETD in regions of complex geometry and the FDTD elsewhere the advantages of both are combined. However, previous work only addressed mixed first order (i.e. second order accurate) methods. For electrically large problems or when very accurate solutions are required, higher order methods are attractive. In this thesis a novel higher order implicit/explicit FETD method of arbitrary order in space is presented. A higher order explicit FETD method is implemented using Gauss-Lobatto lumping on regular Cartesian hexahedra with central differencing in time applied to a coupled Maxwell’s equation FEM formulation. This can be seen as a spatially higher order generalisation of the FDTD. A convolution-free perfectly matched layer (PML) method is adapted from the FDTD literature to provide mesh termination. A curl conforming hybrid mesh allowing the interconnection of arbitrary order tetrahedra and hexahedra without using intermediate pyramidal or prismatic elements is presented. An unconditionally stable implicit FETD method is implemented using Newmark-Beta time integration and the standard curl-curl FEM formulation. The implicit/explicit hybrid is constructed on the hybrid hexahedral/tetrahedral mesh using the equivalence between the coupled Maxwell’s formulation with central differences and the Newmark-Beta method with Beta = 0 and the element-wise implicitness method. The accuracy and efficiency of this hybrid is numerically demonstrated using several test-problems.
Malkowski, Susan Kate. "MAGNETIC SHIELDING STUDIES FOR THE NEUTRON ELECTRIC DIPOLE MOMENT EXPERIMENT AT THE SPALLATION NEUTRON SOURCE." UKnowledge, 2011. http://uknowledge.uky.edu/physastron_etds/1.
Повний текст джерелаSkorpen, Sarah Anne. "The Application and interpretation of linear finite element analysis results in the design and detailing of hogging moment regions in reinforced concrete flat plates." Diss., University of Pretoria, 2013. http://hdl.handle.net/2263/40823.
Повний текст джерелаDissertation (MEng)--University of Pretoria, 2013.
gm2014
Civil Engineering
unrestricted
Bhat, Akshaykumar. "Evaluation of Beam-to-Column Gravity Moment Connections." University of Cincinnati / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1613685862606626.
Повний текст джерелаTuna, Mehmet. "Inelastic Panel Zone Deformation Demands In Steel Moment Resisting Frames." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614329/index.pdf.
Повний текст джерелаhowever, panel zones designed according to FEMA 355D showed minimal yielding for both shallow and deep beam configurations. Based on the analysis results, local shear strain demands in panel zones were expressed as a function of interstory drifts and normalized panel zone thicknesses.
Schippers, Jared D. "A Design Procedure for Bolted Top-and-Seat Angle Connections for Use in Seismic Applications." University of Cincinnati / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1336137999.
Повний текст джерелаShankar, H. N. "Adaptive Control Of A General Class Of Finite Dimensional Stable LTI Systems." Thesis, Indian Institute of Science, 2000. http://hdl.handle.net/2005/225.
Повний текст джерелаToellner, Bradley W. "Evaluating the Effect of Decking Fasteners on the Seismic Behavior of Steel Moment Frame Plastic Hinge Regions." Thesis, Virginia Tech, 2013. http://hdl.handle.net/10919/23171.
Повний текст джерелаFull-scale connection testing is the most accurate way to investigate the behavior of different moment connections with common defects and fasteners applied in the protected zone. However, it is cost prohibitive to conduct full-scale testing programs that are sufficiently comprehensive to investigate a wide range of defect types, severity, and locations. For this reason, it is desired to develop alternative methods of investigation. A finite element (FE) model capable of simulating both the global deformation patterns and local buckling effects in a moment connection has been developed. Validated FE models will allow for further evaluation through numerical simulation of additional configurations. Furthermore, alternate, more economical, test configurations to experimentally investigate the effect of defects on steel moment connections were explored. This report discusses the full-scale test setup, results and analysis of completed experimental testing, the development of an FE connection model, and the preliminary development of alternate test configurations.
Master of Science
Choucair, Israa. "A Four-dimensional Approach to Finite Element Method for the Large Transformations of Materials." Thesis, Troyes, 2021. http://www.theses.fr/2021TROY0025.
Повний текст джерелаA space-time description of the finite transformations of thermo-mechanical continua is developed: the use of such a four-dimensional approach guarantees the general covariance of the proposed models. The conservation equations are written in this context and a constitutive model is derived for reversible transformations. We use projection operators to obtain the space and time components of the 4D governing equations and to interpret the results. We next propose a weak formulation of the problem along with its finite-element discretization, to be solved for the finite transformations of a solid. The advantage of this description is that the integration on space and time is performed in one step. We discuss why the 4D convective coordinate system is of interest to solve the problem. Finally, we illustrate the approach with analytical examples and solve thermo-mechanical problems numerically with an implementation on FEniCS software
Hotz, Carl. "MOMENT REDUCTION ANALYSIS OF BUILT-UP I-SECTION EXPOSED TO UNIFORM CORROSION." University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron1525293365942438.
Повний текст джерелаMojsejenko, Dimitri. "ESTIMATING PASSIVE MATERIAL PROPERTIES AND FIBER ORIENTATION IN A MYOCARDIAL INFARCTION THROUGH AN OPTIMIZATION SCHEME USING MRI AND FE SIMULATION." UKnowledge, 2014. http://uknowledge.uky.edu/me_etds/41.
Повний текст джерелаYang, Jie. "Structural behaviour of concrete-filled elliptical column to I-beam connections." Thesis, University of Bradford, 2017. http://hdl.handle.net/10454/16022.
Повний текст джерелаSchütz, Jochen [Verfasser]. "A hybrid mixed finite element scheme for the compressible Navier-Stokes equations and adjoint-based error control for target functionals / Jochen Schütz." Aachen : Hochschulbibliothek der Rheinisch-Westfälischen Technischen Hochschule Aachen, 2011. http://d-nb.info/1018186158/34.
Повний текст джерелаFayez, Moustafa Moawad Ragab. "Approximation of The Neutron Diffusion Equation on Hexagonal Geometries Using a h-p finite element method." Doctoral thesis, Universitat Politècnica de València, 2016. http://hdl.handle.net/10251/65353.
Повний текст джерела[ES] La ecuación de la difusión neutrónica es una aproximación de la ecuación del transporte de neutrones que describe la población de neutrones en el núcleo de un reactor nuclear. En particular, consideraremos reactores de tipo VVER y para simular su comportamiento se utilizará la ecuación de la difusión neutrónica para cuya discretización se hace uso de mallas hexagonales. La mayoría de los códigos de simulación de reactores nucleares utilizan aproximación multigrupo de energía de la ecuación de la difusión neutrónica para describir la distribución de neutrones en el interior del núcleo del reactor. Para estudiar el estado estacionario del reactor, es posible forzar la criticidad del reactor de forma artificial modificando las secciones eficaces de forma que se obtiene un problema de valores propios diferencial, conocido como el problema de los Modos Lambda, que se resuelve para obtener los valores propios dominantes del reactor y sus correspondientes funciones propias. Para discretizar este modelo se ha hecho uso de un método de elementos finitos con adaptabilidad h-p. Este método permite el uso de mallas heterogéneas, y de diferentes refinamientos como el uso mallas h-adaptativas, reduciendo el tamaño de los distintos nodos, y el p-refinado, aumentando el grado del polinomio de las funciones básicas utilizado en los desarrollos de la solución en los diferentes nodos. Se ha desarrollado un código basado en un método de elementos finitos de alto orden para resolver el problema de los Modos Lambda en un reactor con geometría hexagonal y se han obtenido los Modos dominantes para distintos problemas de referencia. Una vez que se ha obtenido la solución para la distribución de neutrones en estado estacionario, ésta se utiliza como condición inicial para la integración de la ecuación de difusión neutrónica dependiente del tiempo. Para simular el comportamiento de un reactor nuclear para un determinado transitorio, es necesario ser capaz de integrar la ecuación de la difusión neutrónica dependiente del tiempo en el interior del núcleo del reactor. La discretización espacial de esta ecuación se hace usando un método de elementos finitos de alto orden que permite refinados de tipo h-p para distintas geometrías. Los transitorios que implican el movimiento de los bancos de las barras de control tienen el problema conocido como el efecto 'rod-cusping'. Estudios anteriores, por lo general, han abordado este problema utilizando una malla fija y definiendo propiedades promedio para los materiales correspondientes a las celdas donde se tiene la barra de control parcialmente insertada. En el presente trabajo se propone el uso de un esquema de malla móvil, de forma que en mallado espacial va cambiando con el movimiento de la barra de control, evitando la necesidad de utilizar secciones eficaces equivalentes para las celdas parcialmente insertadas. El funcionamiento de este esquema de malla móvil propuesto se estudia resolviendo distintos problemas tipo. La precisión obtenida mediante de la teoría de la difusión en los cálculos de reactores es limitada cuando se tienen elementos de combustible complejos o se pretenden realizar cálculos en malla fina. Para mejorar estos resultados, es necesario disponer de un método que incorpore aproximaciones de orden superior de la ecuación del transporte de neutrones. Una posibilidad es hacer uso de las ecuaciones PN simplificadas (SPN ). En este trabajo se utiliza un método de elementos finitos h-p para obtener los modos dominantes asociados con una configuración dada del núcleo de un reactor nuclear con geometría hexagonal usando la aproximación SPN . El funcionamiento de las aproximaciones SPN (N = 1, 3, 5) se ha estudiado para distintos problemas de referencia.
[CAT] L'equació de la difusió neutrònica és una aproximació de l'equació del transport de neutrons que descriu la població de neutrons en el nucli de un reactor nuclear. En particular, considerarem reactors de tipus VVER i per a simular el seu comportament s'utilitzarà l'equació de la difusió neutrónica que es discretitza fent ús de malles hexagonals. La majoria dels codis de simulació de reactors nuclears utilitzen l'aproximació multigrup d'energia de l'equació de la difusió neutrónica per a descriure la distribució de neutrons a l'interior del nucli del reactor. Per a estudiar l'estat estacionari del reactor, és possible forçar la seua criticitat de forma artificial modificant les seccions eficaces de manera que s'obté un problema de valors propis diferencial, conegut com el problema dels Modes Lambda, que es resol per a obtenir els valors propis dominants del reactor i les seues corresponents funcions pròpies. Per a discretitzar aquest model s'ha fet ús d'un mètode d'elements finits amb adaptabilitat h-p. Aquest mètode permet l'ús de malles heterogènies, i de diferents refinaments com l'ús malles h-adaptatives, reduint la grandària dels diferents nodes, i el p-refinat, augmentant el grau del polinomi de les funcions bàsiques utilitzat en els desenvolupaments de la solució en els diferents nodes. S'ha desenvolupat un codi basat en un mètode d'elements finits d'alt ordre per a resoldre el problema dels Modes Lambda en un reactor amb geometria hexagonal i s'han obtingut els Modes dominants per a diferents problemes de referència. Una vegada que s'ha obtingut la solució per a la distribució de neutrons en estat estacionari, aquesta s'utilitza com a condició inicial per a la integració de l'equació de difusió neutrònica depenent del temps. Per a simular el comportament d'un reactor nuclear per a un determinat transitori, és necessari ser capaç d'integrar l'equació de la difusió neutrónica depenent del temps a l'interior del nucli del reactor. La discretitzación espacial d'aquesta equació es fa usant un mètode d'elements finits d'alt ordre que permet refinats de tipus h-p per a diferents geometries. Els transitoris que impliquen el moviment dels bancs de les barres de control tenen el problema conegut com l'efecte 'rod-cusping'. Estudis anteriors, en general, han abordat aquest problema utilitzant una malla fixa i definint propietats equivalents per als materials corresponents a les cel·les on es té la barra de control parcialment inserida. En el present treball es proposa l'ús d'un esquema de malla mòbil, de manera que en mallat espacial va canviant amb el moviment de la barra de control, evitant la necessitat d'utilitzar seccions eficaces equivalents per a les cel·les parcialment inserides. El funcionament de aquest esquema de malla mòbil s'estudia resolent diferents problemes tipus. La precisió obtinguda mitjançant de la teoria de la difusió en els càlculs de reactors és limitada quan es tenen elements de combustible complexos o es pretenen realitzar càlculs en malla fina. Per a millorar aquests resultats, és necessari disposar d'un mètode que incorpore aproximacions d'ordre superior de l'equació del transport de neutrons. Una possibilitat és fer ús de les equacions PN simplificades (SPN ). En aquest treball s'utilitza un mètode d'elements finits h- p per a obtenir els modes dominants associats amb una configuració donada del nucli de un reactor amb geometria hexagonal usant l'aproximació SPN . El funcionament de les aproximacions SPN (N = 1, 3, 5) s'ha estudiat per a diferents problemes de referència.
Fayez Moustafa Moawad, R. (2016). Approximation of The Neutron Diffusion Equation on Hexagonal Geometries Using a h-p finite element method [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/65353
TESIS
Forrester, Merville Kenneth. "Stiffness Model of a Die Spring." Thesis, Virginia Tech, 1998. http://hdl.handle.net/10919/32249.
Повний текст джерелаMaster of Science
Emilia, Wallin. "Jämförelse av beräkningsmetoder för lastspridning i tvärled vid brobaneplattor av betong." Thesis, KTH, Betongbyggnad, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-169916.
Повний текст джерелаThe aim of this thesis is to study different design methods for determing load distribution, and design values for shear force and bending moment in concrete bridge decks. The study was performed based on three design methods for hand calculations, which have been compared to the results from finite element modelling (FEM). The load distribution has a major impact on the design of a bridge and how the results from different design methods will correlate is of a great interest. The evaluation has been performed on one case study, wich is an eight-meter wide composite girder bridge in Njurunda, situated south of Sundsvall in Sweden. The traffic loads applied for this study was load model 1 and load model 2 prescribed in Eurocode (CEN, 2003). One of the design methods investigated is a method used to determine for bending moment for a cantilever slab. A significant impact from the edge beam utilizes by the method to calculate the bending moment. The second method is a design method for shear forces recommended by The Swedish Transport Administration. The third and last design methods for hand calculation is to use influence charts by Pucher (Pucher, 1977). By using the influence chart to calculate the maximum bending moment in mid-span. Results from different models, created with FEM, were compared to the results from hand calculations. The bridge slab was modelled with shell elements, and the girders of the bridge were modelled in four different ways to study the impact of the level of detail in the numerical models. The results in this report show that hand calculation methods are based on significant simplifications of the structure and these may have a major impact on the results. The relation between results from hand calculation methods and results obtained with FEM was not consistent in all cases analysed. While studying the bending moment for a cantilever slab, the main conclusion was that the simplifications in the hand calculation methods resulted in significantly higher moments compared to the FE-calculations. Regarding design for shear forces, the FE analyses resulted in nearly twice as high shear forces compared to the hand calculation methods. While using the influence charts by Pucher the relation between results from hand calculations and results from FEM was not consistent. Conclusions from the study included that the simplifications in hand calculations is hard to change. These simplifications can have a major influence to the results. Some simplifications will make the results more on the safe side. With FEM the user is more free to choose which simplifications that will be made, but it can sometimes be hard to see the effect simplifications have on the results. Concrete is a complex material and design methods based on empirical studies does most likely give a result that reflects the reality better than methods based on mathematic theories.
Fadeel, Abdalsalam. "Development and Application of a Computational Modeling Scheme for Periodic Lattice Structures." Wright State University / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=wright162248153014535.
Повний текст джерелаVotava, Ondřej. "Návrh oběžného kola radiální turbíny se sníženým momentem setrvačnosti." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2020. http://www.nusl.cz/ntk/nusl-432805.
Повний текст джерелаNair, Dileep 1976. "An accuracy controlled combined adaption-optimization scheme for improving the performance of 3D microwave devices over a frequency band /." Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=115714.
Повний текст джерелаThis thesis presents a software system that minimizes the return loss of 3D microwave devices over a frequency band efficiently through accuracy control. It combines a custom gradient-based optimizer with a p-adaptive frequency-domain finite element solver. The solver computes the cost function and its gradient to a specified accuracy in a cost efficient manner. The p-adaptive solver comprises of two original components: an a-posteriori error estimator to evaluate the error in the cost function gradient, and an error indicator to identify the high error regions in the mesh. The optimizer controls the accuracy of the cost function evaluation through a link with the solver, specifying the required relative error for the gradient at each optimization step.
The combined adaption-optimization scheme was applied to 3D rectangular waveguide problems for validation: an E-plane miter bend, a U-bend, an impedance transformer and a compensated magic-T. For comparison, all the problems were also optimized using high-order finite elements at every step. Test results prove the computational efficiency of the new combined scheme at various stages of the optimization. In the early stages, when the element orders are low, the scheme is able to attain similar cost function reductions as the high-order analysis, with computational savings up to a factor of 25. Even in the late stages, when the accuracy is more stringent, the scheme manages a reduction in cumulative computation time of at least a factor of 4.
Snow, Scott Karl. "Numerical Analysis of Passive Force on Skewed BridgeAbutments with Reinforced Concrete Wingwalls." BYU ScholarsArchive, 2008. https://scholarsarchive.byu.edu/etd/7399.
Повний текст джерелаYang, Mingming. "Development of the partition of unity finite element method for the numerical simulation of interior sound field." Thesis, Compiègne, 2016. http://www.theses.fr/2016COMP2282/document.
Повний текст джерелаIn this work, we have introduced the underlying concept of PUFEM and the basic formulation related to the Helmholtz equation in a bounded domain. The plane wave enrichment process of PUFEM variables was shown and explained in detail. The main idea is to include a priori knowledge about the local behavior of the solution into the finite element space by using a set of wave functions that are solutions to the partial differential equations. In this study, the use of plane waves propagating in various directions was favored as it leads to efficient computing algorithms. In addition, we showed that the number of plane wave directions depends on the size of the PUFEM element and the wave frequency both in 2D and 3D. The selection approaches for these plane waves were also illustrated. For 3D problems, we have investigated two distribution schemes of plane wave directions which are the discretized cube method and the Coulomb force method. It has been shown that the latter allows to get uniformly spaced wave directions and enables us to acquire an arbitrary number of plane waves attached to each node of the PUFEM element, making the method more flexible.In Chapter 3, we investigated the numerical simulation of propagating waves in two dimensions using PUFEM. The main priority of this chapter is to come up with an Exact Integration Scheme (EIS), resulting in a fast integration algorithm for computing system coefficient matrices with high accuracy. The 2D PUFEM element was then employed to solve an acoustic transmission problem involving porous materials. Results have been verified and validated through the comparison with analytical solutions. Comparisons between the Exact Integration Scheme (EIS) and Gaussian quadrature showed the substantial gain offered by the EIS in terms of CPU time.A 3D Exact Integration Scheme was presented in Chapter 4, in order to accelerate and compute accurately (up to machine precision) of highly oscillatory integrals arising from the PUFEM matrix coefficients associated with the 3D Helmholtz equation. Through convergence tests, a criteria for selecting the number of plane waves was proposed. It was shown that this number only grows quadratically with the frequency thus giving rise to a drastic reduction in the total number of degrees of freedoms in comparison to classical FEM. The method has been verified for two numerical examples. In both cases, the method is shown to converge to the exact solution. For the cavity problem with a monopole source located inside, we tested two numerical models to assess their relative performance. In this scenario where the exact solution is singular, the number of wave directions has to be chosen sufficiently high to ensure that results have converged. In the last Chapter, we have investigated the numerical performances of the PUFEM for solving 3D interior sound fields and wave transmission problems in which absorbing materials are present. For the specific case of a locally reacting material modeled by a surface impedance. A numerical error estimation criteria is proposed by simply considering a purely imaginary impedance which is known to produce real-valued solutions. Based on this error estimate, it has been shown that the PUFEM can achieve accurate solutions while maintaining a very low computational cost, and only around 2 degrees of freedom per wavelength were found to be sufficient. We also extended the PUFEM for solving wave transmission problems between the air and a porous material modeled as an equivalent homogeneous fluid. A simple 1D problem was tested (standing wave tube) and the PUFEM solutions were found to be around 1% error which is sufficient for engineering purposes
Birgersson, Fredrik. "Prediction of random vibration using spectral methods." Doctoral thesis, KTH, Aeronautical and Vehicle Engineering, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3694.
Повний текст джерелаMuch of the vibration in fast moving vehicles is caused bydistributed random excitation, such as turbulent flow and roadroughness. Piping systems transporting fast flowing fluid isanother example, where distributed random excitation will causeunwanted vibration. In order to reduce these vibrations andalso the noise they cause, it is important to have accurate andcomputationally efficient prediction methods available.
The aim of this thesis is to present such a method. Thefirst step towards this end was to extend an existing spectralfinite element method (SFEM) to handle excitation of planetravelling pressure waves. Once the elementary response tothese waves is known, the response to arbitrary homogeneousrandom excitation can be found.
One example of random excitation is turbulent boundary layer(TBL) excitation. From measurements a new modified Chase modelwas developed that allowed for a satisfactory prediction ofboth the measured wall pressure field and the vibrationresponse of a turbulence excited plate. In order to model morecomplicated structures, a new spectral super element method(SSEM) was formulated. It is based on a waveguide formulation,handles all kinds of boundaries and its elements are easily putinto an assembly with conventional finite elements.
Finally, the work to model fluid-structure interaction withanother wave based method is presented. Similar to the previousmethods it seems to be computationally more efficient thanconventional finite elements.
Linß, Torsten. "Layer-adapted meshes for convection-diffusion problems." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2008. http://nbn-resolving.de/urn:nbn:de:bsz:14-ds-1203582105872-58676.
Повний текст джерелаRůžek, Patrik. "Posouzení ovladatelnosti sektoru jezového pole VD Roudnice nad Labem při extrémních povodňových stavech." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2017. http://www.nusl.cz/ntk/nusl-394045.
Повний текст джерелаKurniawan, Cyrilus Winatama. "Flexural behaviour and design of the new LiteSteel beams." Queensland University of Technology, 2007. http://eprints.qut.edu.au/16674/.
Повний текст джерелаLinß, Torsten. "Layer-adapted meshes for convection-diffusion problems." Doctoral thesis, Technische Universität Dresden, 2006. https://tud.qucosa.de/id/qucosa%3A24058.
Повний текст джерелаMikmek, Vladislav. "Vliv vinutí na vlastnosti asynchronního motoru." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2020. http://www.nusl.cz/ntk/nusl-413054.
Повний текст джерелаZHOU, FENGFENG. "MODEL-BASED SIMULATION OF STEEL FRAMES WITH ENDPLATE CONNECTIONS." University of Cincinnati / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1119316578.
Повний текст джерелаWanniarachchi, Somadasa. "Flexural behaviour and design of cold-formed steel beams with rectangular hollow flanges." Queensland University of Technology, 2005. http://eprints.qut.edu.au/29810/.
Повний текст джерелаYaqoob, Saima. "BRIDGE EDGE BEAM : NON-LINEAR ANALYSIS OF REINFORCEDCONCRETE OVERHANG SLAB BY FINITEELEMENT METHOD." Thesis, KTH, Bro- och stålbyggnad, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-222806.
Повний текст джерелаGottwald, Michal. "Dynamický model stejnosměrného motoru s využitím metody konečných prvků." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2011. http://www.nusl.cz/ntk/nusl-219003.
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