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Search results for: FINITE ELEMENT METHOD, MODEL ORDER REDUCTION, PASSIVE MICROWAVE STRUCTURES
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Wave-induced stress and breaking of sea ice in a coupled hydrodynamic discrete-element wave–ice model
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MHD darcy-forchheimer nanofluid flow and entropy optimization in an odd-shaped enclosure filled with a (MWCNT-Fe3O4/water) using galerkin finite element analysis
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Reduced order models in computational electromagnetics (in memory of Ruediger Vahldieck)
PublicationThis paper reviews research of Ruediger Vahldieck's group and the group at the Gdansk University of Technology in the area of model order reduction techniques for accelerating full-wave simulations. The applications of reduced order models to filter design as well as of local and nested(multilevel) macromodels for solving 3D wave equations and wave-guiding problems using finite difference and finite element methods are discussed.
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Non-destructive testing of industrial structures with the use of multi-camera Digital Image Correlation method
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Mixture Model Based Efficient Method for Magnetic Resonance Spectra Quantification
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Investigation method and mathematical model of pressure losses in hydraulic rotary motor
PublicationTis paper presents a way of determining the coefcient k of the pressure losses Δp (fow drag) in internal ducts 8 Mp of SWSB-63 hydraulic motor. Te coefcient is determined at a fow rate equal to the theoretical capacity Q of the Pt pump feeding the motor , the losses are related to the nominal pressure p in the hydraulic system. Te investigations n followed a model of energy performance of hydraulic rotary motor, proposed by...
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Modeling of heat and fluid flow in granular layers using high-order compact schemes and volume penalization method
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Investigations of quasi-static vortex structures in 2D sand specimen under passive earth pressure conditions based on DEM and Helmholtz-Hodge vector field decomposition.
PublicationArtykuł przedstawia wyniki obliczeń quasi-statycznych struktur wirowych w 2-wymiarowej próbce piasku w warunkach pasywnego parcia gruntu. Zastosowano metodę elementów dyskretnych i dekompozycję Helmholtza-Hodge’a pola wektorowego. Stwierdzono bliską zależność między wirami a miejscem powstania strefy lokalizacji odkształceń stycznych.
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Comparative Study on Effects of Thermal Gradient Direction on Heat Exchange between a Pure Fluid and a Nanofluid: Employing Finite Volume Method
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Large eddy simulations of wall-bounded flows using a simplified immersed boundary method and high-order compact schemes
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Modal analysis of a steel grandstand
PublicationAmong the issues related to the idea of sustainable society is the safety of civil engineering structures devoted to satisfy different needs of people. One of the types of structures devoted to satisfy recreational needs are grandstands, which are used during sport events or music concerts. It is obligatory to consider interaction between structure and crowd load especially when the crowd movement involves rhythmic jumping, dancing,...
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A model for performance assessment of damaged ships when usig the risk-based method
PublicationArtykuł prezentuje elementy badań związanych z rozwojem metody i modelu do oceny bezpieczeństwa statków i obiektów oceanotechnicznych w stanie uszkodzonym. Przedsawiono podejście do oceny bezpieczeństwa statków i obiektów oceanotechnicznych,składające się z dwóch części: oceny zachowania się obiektów oraz oceny ryzyka. Głównym problemem zaprezentowanym w arytkule jest ocena ocena zachowania się statków i obiektów oceanotechnicznych...
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A model for performance assessment of damaged ships when using the risk-based method
PublicationW pracy omówiono metody oceny bezpieczeństwa statków w stanie uszkodzonym w warunkach operacyjnych. Przedstawiono metodę oceny bezpieczeństwa statków w stanie uszkodzonym opartą na analizie ryzyka. Przedstawiono model oceny zachowania się statku w stanie uszkodzonym, który jest oparty na tak zwanym quasi-dynamicznym modelu zatapiania statku. Omówiono elementy związane z analizą ryzyka i ocena bezpieczenstwa statków.
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Model reference method and continuous-time system identification in tuning the PID controllers.
PublicationW pracy opisano zagadnienie doboru nastaw sterowników PID w układach regulacji automatycznej. W rozważaniach wzięto pod uwagę zarówno klasyczną strukturę jednopętlowego układu sterowania z regulatorem PID umieszczonym w torze głównym, jak też odmienną realizację I-PD z członem całkującym występującym w torze głównym i sterownikiem proporcjonalno-różniczkującym ulokowanym w dodatkowej pętli sprzężenia zwrotnego. Ponieważ powszechnie...
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Modelling of in-plane wave propagation in a plate using spectral element method and Kane–Mindlin theory with application to damage detection
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Meso-mechanical modelling of damage in concrete using discrete element method with porous ITZs of defined width around aggregates.
PublicationArtykuł omawia wyniki obliczeń numerycznych pękania dla betonu stosując metodę elementów dyskretnych. Beton był opisany jako materiał 4-fazowy i był poddany zginaniu. W obliczeniach uwzględniono strefy ITZ o skończonej szerokości dookoła wszystkich ziaren kruszywa. Nacisk położono na przebieg mikropęknięć przy kruszywie. Wyniki porównano bezpośrednio z doświadczeniami. Obliczenia wykonano także dla szorstkich ziaren kruszywa....
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Application of 3D Digital Image Correlation for Development and Validation of FEM Model of Self-Supporting Arch Structures
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Model identification in urban structures revitalisation = Metody identyfikacji modeli stosowane w rewitalizacji budowli miejskich
PublicationW pracy zaprezentowano wybrane metody diagnostyki dynamicznej stosowane w identyfikacji modeli budowli zabytkowych. Do tego celu wykorzystano pomiary częstości i postaci drgań własnych budowli poddanych oddziaływaniom środowiskowych. Wykazano efektywność stosowanych metod identyfikacji parametrycznej modeli oraz identyfikacji uszkodzeń na przykładzie trzech budowli: dzwonnicy Archikatedry w Wilnie, wieży Twierdzy Wisłoujście w...
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Smart acoustic band structures
PublicationSmart acoustic band structures exhibit very interesting and non-standard physical properties due to the periodic nature of their certain characteristic on different scale levels. They manifest mostly in their frequency spectra as socalled frequency band-gaps or stop-bands, what has a great impact on the behaviour of these structures in relation to the propagation of vibro-acoustic signals that can be transmitted through the structures...
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Microwave plasma treatment of simulated biomass syngas: Interactions between the permanent syngas compounds and their influence on the model tar compound conversion
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A 3D-FEM mesh technique for fast analysis of waveguide problems containing rotatable tuning elements
PublicationIn this paper a meshing technique for 3D Finite Element Method is presented. It allows for fast analysis and optimization of the waveguide structures, which contain rotatable tuning elements. In the proposed procedure a thin layer of varying cylindrical mesh buffer is introduced in order to reuse unchanged mesh and FEM matrices in the rest of the domain.
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Solving Boundary Value Problems for Second Order Singularly Perturbed Delay Differential Equations by ε-Approximate Fixed-Point Method
PublicationIn this paper, the boundary value problem for second order singularly perturbed delay differential equation is reduced to a fixed-point problem v = Av with a properly chosen (generally nonlinear) operator A. The unknown fixed-point v is approximated by cubic spline vh defined by its values vi = vh(ti) at grid points ti, i = 0, 1, ... ,N. The necessary for construction the cubic spline and missing the first derivatives at the boundary...
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Hybrid Analysis of Structures Composed of Axially Symmetric Objects
Publication— A hybrid method for the scattering problems in shielded and open structures is presented. The procedure is based on the combination of body-of-revolution involving finite-element methods with impedance matrix formulation and the mode-matching technique, which can be utilized for the analysis of structures with axially symmetrical scatterers. In order to confirm the validity and efficiency of the proposed approach, a few examples...
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Application of 3D digital image correlation for development and validation of FEM model of self-supporting metal plates structures
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Monitoring of deep foundation deflection in model experiments by means of a magnetic method: theoretical study.
PublicationZaproponowano oryginalną nieinwazyjną metodę pomiaru ugięcia pali bocznie obciążonych niespoistymi i małospoistymi gruntami suchymi lub wilgotnymi. Metoda ma zastosowanie do pomiaru ugięcia pali i ścian szczelnych oraz określania położenia innych fundamentów lub elementów zagłębionych w gruncie.
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The Finite Elements Method application to assesment the impact of turbulence generated by wind turbines on their lacation inclose proximity of overhead high voltage power transmissionlines
PublicationThe paper presents selected aspects of construction of wind turbines location concerning aerodynamic impact on power lines. Reaserch is based on the source data concerning the aerodynamic impact of a wind farm consisting of 8 turbines and 400 kV power line, an analysis of the possibility of wind farm locating in the immediate vicinity of the line was carried out. There are serious problems with locating higher capacity wind farms...
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Domain Reduction in Hybrid Technique for Electromagnetic Wave Scattering Problems
PublicationThis paper proposes a combination of the field matching technique, finite element method and generalized impedance matrix, the main idea of which is to reduce the computational domain by surrounding a scatterer with the smallest convex shape and applying the field matching technique. This approach can be applied for arbitrary shaped scatterers and types of materials and allows for the reduction of the computational domain. In order...
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The Design of Cavity Resonators and Microwave Filters Applying Shape Deformation Techniques
PublicationThis article introduces shape deformation as a new approach to the computer-aided design (CAD) of high-frequency components. We show that geometry deformation opens up new design possibilities and offers additional degrees of freedom in the 3-D modeling of microwave structures. Such design flexibility is highly desirable if the full potential of additive manufacturing (AM) is to be exploited in the fabrication of RF and microwave...
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Wave-induced stress and breaking of sea ice in a coupled hydrodynamic–discrete-element wave–ice model
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Wave-induced stress and breaking of sea ice in a coupled hydrodynamic–discrete-element wave–ice model
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Wave-induced stress and breaking of sea ice in a coupled hydrodynamic–discrete-element wave–ice model
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On the necessity of experimental verification of numerical results in biomedical applications
PublicationPorous structures made of metal or biopolymers with a structure similar in shape and mechanical properties to human bone can be easily produced by stereolitography techniques, e.g. selective laser melting (SLM). Numerical techniques, like finite element method (FEM) have great potential in testing new, even the most sophisticated designs, according to their mechanical properties, i.e. strength or stiffness. However, due to different...
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Method of determination of the reticulocyte age distribution from flow cytometry count by a structured-population model
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Model of identification of events and accident scenarios for a method of risk and safety assessment of ships in damaged conditions
PublicationW pracy opisano podstawowe problemy związane z identyfikacją zdarzeń i scenariuszy wypadku oraz modelowaniem ryzyka dla alternatywnej metody oceny bezpieczeństwa statków w stanie uszkodzonym. Zastosowano podejście do bezpieczeństwa statków oparte na ocenie zachowania się statku i ocenie ryzyka wypadku. Wskazano możliwości zastosowania modelowania do analizy bezpieczeństwa statków na etapie projektowania, w czasie eksploatacji i...
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Macromodels for efficient FEM simulations of waveguides and resonators
PublicationThis paper introduces a novel technique for enhancing the efficiency of the finite element method (FEM) by incorporating special modules, called macromodels, into the standard eigenvalue formulation. The number of unknowns in the separated macromodel subdomain can be significantly reduced by orthogonal projection, using the efficient nodal order reduction algorithm. The idea of macromodels implementation is demonstrated on a simple...
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GPU-Accelerated LOBPCG Method with Inexact Null-Space Filtering for Solving Generalized Eigenvalue Problems in Computational Electromagnetics Analysis with Higher-Order FEM
PublicationThis paper presents a GPU-accelerated implementation of the Locally Optimal Block Preconditioned Conjugate Gradient (LOBPCG) method with an inexact nullspace filtering approach to find eigenvalues in electromagnetics analysis with higherorder FEM. The performance of the proposed approach is verified using the Kepler (Tesla K40c) graphics accelerator, and is compared to the performance of the implementation based on functions from...
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Reduced model of gyroscopic system
PublicationThe paper presents the method of model reduction for the system with gyroscopic interactions. Two methods were used to obtain the approximate discrete models of the continuous structure: the modal decomposition method and the rigid finite element method. The first approach is used for this part of a system for which it is easy to formulate orthogonality conditions, meanwhile the second one is used for other part. The method enables...
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Towards a Method Evaluating Control Actions in STPA-Based Model of Ship-Ship Collision Avoidance Process
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Toward a Method Evaluating Control Actions in STPA-Based Model of Ship-Ship Collision Avoidance Process
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Inverse method for 2D viscous flow design problem using stream-function coordinates for axisymmetric model
PublicationOpracowano metodę odwrotną dla przepływów lepkich nieściśliwych w osiowosymetrycznej konfiguracji. Użyto współrzędnych funkcji prądu mających tą właściwość, iż możliwe jest zastapienie jednej współrzędnej geometrycznej zmienną zależną od prędkości przepływu. W związku z czym możliwe jest rozwiązanie zadania projektowego. Metodę rozwiązano numerycznie dla przypadku testowego jak i pokazano możliwości metody dla bardziej skomplikowanego...
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Accuracy analysis of 3D model obtained by photogrammetric method on the example of historic room from Wisłoujście Fortress
PublicationThe article presents a comparison of obtained models of a test object. Close range photogrammetry was used to obtain 3D models. As test object was used one of the rooms located in Wisłoujście Fortress in Gdańsk, Poland. Different models were obtained by using different distribution and number of reference points. Article contains analysis of differences between coordinates of control points obtained from total station measurements...
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Laplace domain BEM for anisotropic transient elastodynamics
PublicationIn this paper, we describe Laplace domain boundary element method (BEM) for transient dynamic problems of three-dimensional finite homogeneous anisotropic linearly elastic solids. The employed boundary integral equations for displacements are regularized using the static traction fundamental solution. Modified integral expressions for the dynamic parts of anisotropic fundamental solutions and their first derivatives are obtained....
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Extension of the Force Matching Method to Anisotropic Coarse-Grained Transferable Force Fields: Application to the Unres Model of Proteins
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Energy Efficiency Analysis of Railway Turnout Heating With a Simplified Snow Model Using Classical and Contactless Heating Method
PublicationElectrical heating of railway turnouts is a considerable technical and economic challenge, hence the need to conduct research for optimisation of a railway turnouts heating system. This paper presents results of a numerical analysis and experimental research on heating systems mounted on rail turnouts in line with the classical method and including a heater thermally insulated from the base of a rail. The numerical calculations...
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Rapid Microwave Design Optimization in Frequency Domain Using Adaptive Response Scaling
PublicationIn this paper, a novel methodology for cost-efficient microwave design optimization in the frequency domain is proposed. Our technique, referred to as adaptive response scaling (ARS), has been developed for constructing a fast replacement model (surrogate) of the high-fidelity electromagnetic-simulated model of the microwave structure under design using its equivalent circuit (low-fidelity model). The basic principle of ARS is...
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A GPU Solver for Sparse Generalized Eigenvalue Problems with Symmetric Complex-Valued Matrices Obtained Using Higher-Order FEM
PublicationThe paper discusses a fast implementation of the stabilized locally optimal block preconditioned conjugate gradient (sLOBPCG) method, using a hierarchical multilevel preconditioner to solve nonHermitian sparse generalized eigenvalue problems with large symmetric complex-valued matrices obtained using the higher-order finite-element method (FEM), applied to the analysis of a microwave resonator. The resonant frequencies of the low-order...
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Computational modelling of historic masonry railroad arch bridges
PublicationThe problems encountered during the analyzes of structural response of historic masonry railroad arch bridges are described in this paper. The attention is mainly focused on the stiffness of the masonry arches, their strengths and appropriate estimation of railroad load intensity. Issues related to computational modelling of two, existing, almost 130 years old masonry arch railroad bridges are presented in this context. The main...
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Design and simulation of a new prototype of piezoelectric cantilever sensor/actuator for analysis of the soft tissues properties
PublicationThis paper is devoted to a new prototype of piezoelectric cantilever transducer dedicated for the characterization of the mechanical properties of soft tissues. General description of the actuator’s structure is presented including the basic principles of the measurement. The chosen geometry of the prototype is discussed and compared with the existing one. Constitutive equations are presented for the active and passive layer of...
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A new prototype of piezoelectric bending resonant transducer for analysis of soft tissues properties
PublicationThis paper is devoted to a new piezoelectric bending resonant transducer prototype dedicated to the characterization of the mechanical properties of soft tissue. A general description of the actuator’s structure is presented including the basic principles of the measurement. The chosen geometry of the prototype is discussed and compared with the existing version. Constitutive equations are presented for the active and passive layer...
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Contact with coupled adhesion and friction: Computational framework, applications, and new insights
PublicationContact involving soft materials often combines dry adhesion, sliding friction, and large deformations. At the local level, these three aspects are rarely captured simultaneously, but included in the theoretical models by Mergel et al., (2019). We here develop a corresponding finite element framework that captures 3D finite-strain contact of two deformable bodies. This framework is suitable to investigate sliding friction even...