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Search results for: NUMERICAL METHOD
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Numerical and Experimental Study of Propeller Ventilation
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Numerical and Experimental Study of Propeller Ventilation
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Impact of the Finite Element Mesh Structure on the Solution Accuracy of a Two-Dimensional Kinematic Wave Equation
PublicationThe paper presents the influence of the finite element mesh structure on the accuracy of the numerical solution of a two-dimensional linear kinematic wave equation. This equation was solved using a two-level scheme for time integration and a modified finite element method with triangular elements for space discretization. The accuracy analysis of the applied scheme was performed using a modified equation method for three different...
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Discussion of “Development of an Accurate Time integration Technique for the Assessment of Q-Based versus h-Based Formulations of the Diffusion Wave Equation for Flow Routing” by K. Hasanvand, M.R. Hashemi and M.J. Abedini
PublicationThe discusser read the original with great interest. It seems, however, that some aspects of the original paper need additional comments. The authors of the original paper discuss the accuracy of a numerical solution of the diffusion wave equation formulated with respect to different state variables. The analysis focuses on nonlinear equations in the form of a single transport equation with the discharge Q (volumetric flow rate)...
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Optimization of the Hardware Layer for IoT Systems using a Trust Region Method with Adaptive Forward Finite Differences
PublicationTrust-region (TR) algorithms represent a popular class of local optimization methods. Owing to straightforward setup and low computational cost, TR routines based on linear models determined using forward finite differences (FD) are often utilized for performance tuning of microwave and antenna components incorporated within the Internet of Things systems. Despite usefulness for design of complex structures, performance of TR methods...
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A method of predicting the best conditions for large-size workpiece clamping to reduce vibration in the face milling process
PublicationThe paper presents an innovative method of solving the problem of vibration suppression during milling of large-size details. It consists in searching for the best conditions for clamping the workpiece based on a rapid modal identification of the dominant natural frequencies only and requires repetitive changes in the tightening torque of the clamping screws. Then, by estimating the minimum work of the cutting forces acting in...
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Modelling of Longitudinal Elastic Wave Propagation in a Steel Rod Using the Discrete Element Method
PublicationThe paper deals with the issue of modelling elastic wave propagation using the discrete element method (DEM). The case of a longitudinal wave in a rod with a circular cross-section was considered. A novel, complex algorithm consisting of the preparation of models and simulation of elastic waves was developed. A series of DEM models were prepared for simulations, differing in discretisation and material parameters. Additional calculations...
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Contribution to the capacity analysis of the classic composite girder of Möller
PublicationThe analysis (brief history, experiments, numerical method) of the classic composite girder of Moller has been presented.
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On the convergence of a finite-difference discretization à la Mickens of the generalized Burgers–Huxley equation
PublicationIn this note, we establish the property of convergence for a finite-difference discretization of a diffusive partial differential equation with generalized Burgers convective law and generalized Hodgkin–Huxley reaction. The numerical method was previously investigated in the literature and, amongst other features of interest, it is a fast and nonlinear technique that is capable of preserving positivity, boundedness and monotonicity....
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Discrete element method simulations of fracture in concrete under uniaxial compression based on its real internal structure
PublicationThe paper describes experimental and numerical results of concrete fracture under quasi-static uniaxial compression. Experimental uniaxial compression tests were performed on concrete cubic specimens. Fracture in concrete was detected at the aggregate level by means of three non-destructive methods: three-dimensional X-ray microcomputed tomography, two-dimensional scanning electron microscope and manual two-dimensional digital...
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Towards Robust Identification of Nonstationary Systems
PublicationThe article proposes a fast, two-stage method for the identification of nonstationary systems. The method uses iterative reweighting to robustify the identification process against the outliers in the measurement noise and against the numerical errors that may occur at the first stage of identification. We also propose an adaptive algorithm to optimize the values of the hyperparameters that are crucial for this new method.
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Hybrid Multi-Criteria Method of Analyzing the Location of Distributed Renewable Energy Sources
PublicationThis paper presents the development and the application of a hybrid multi-criteria method, the combination of the Analytic Hierarchy Process (AHP), and numerical taxonomy (NT),to support the decision making on the location of distributed renewable energy sources meetingvarious types of assessment criteria. Finding criteria weights, using the AHP method, eliminates thedisadvantage of NT—which, in current form, is defined by its...
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Special Issue "Applications of Finite Element Modeling for Mechanical and Mechatronic Systems"
PublicationNumerical modeling is very important in today's engineering because, among other things, it reduces the costs associated with prototyping or predicting the occurrence of potentially dangerous situations during operation in certain defined conditions. Different methods have so far been used to implement the real structure into the numerical version. The most popular have been variations of the finite element method (FEM). The aim...
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An Instantaneous Engine Speed Estimation Method Using Multiple Matching Synchrosqueezing Transform
PublicationInstantaneous rotational speed measurement of the engine is crucial in routine inspection and maintenance of an automobile engine. Since the contact measurement of rotational speed is not always available, the vibration measurement has been used for noncontact rotational speed estimation methods. Unfortunately, the accuracy of the noncontact estimation methods by analyzing engine vibration frequency is not satisfactory due to the...
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A novel sandwich footbridge - Practical application of laminated composites in bridge design and in situ measurements of static response
PublicationA novel sandwich composite footbridge is presented in the paper, as an example of practical application of laminated composites in civil engineering. The in situ static load tests of the footbridge before its acceptation for exploitation are shown and discussed. The results are compared with the corresponding ones from a numerical equivalent single layer model of the sandwich structure created within the framework of finite element...
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Full-scale CFD simulations for the determination of ship resistance as a rational, alternative method to towing tank experiments
PublicationResults of ship resistance predictions obtained from towing tank experiments are affected by the method used to extrapolate from a model scale to a ship scale. Selection of method to determine a form factor is subjective and the extrapolation method is accurate for typical hull forms. For innovative hull forms the proper method for calculating the form factor is questionable. Moreover, the influence of the extrapolation method...
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Non-Linear Analysis of Structures Utilizing Load-Discretization of Stiffness Matrix Method with Coordinate Update
PublicationThis paper proposes a stiffness method based structural analysis algorithm for geometrically non-linear structures. In this study, the applied load on the joints has been discretized to a sequence of a few loadings applied. Each loading step produces incremental external nodal displacements, which are added to the corresponding coordinates to get a new geometrical shape of the structure. This process is iteratively repeated until...
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Experimental and Numerical Study on Pounding of Structures in Series
PublicationPounding between structures in series during earthquakes may cause serious damage in the structural elements. The aim of this paper is to show the results of an experimental and numerical study that is focused on pounding between more than two structures which may be described as “structures in series”. In this study, the shaking table experiments, as well as the numerical analyses, were performed using three tower models including...
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Numerical Simulations for Transonic Flow in Control Valve
PublicationResults of numerical simulations for transonic flow in control valve are presented. The valve is the main part of an adaptive pneumatic shock absorber. Flow structure in the valve domain and the influence of the flow non-uniformity in the valve on a mass flow rate is investigated. Numerical simulation results are compared with experimental data.
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Numerical analysis of scale effects in open propellers
PublicationArtykuł przedstawia numeryczne badania efektu skali powodującego różnice w charakterystykach hydrodynamicznych śrub okrętowych wyznaczonych dla skali rzeczywistej i dla skali modelowej. Zaprezentowano wyniki obliczeń dla trzech przykładowych śrub, pokazując poprawki na efekt skali wyznaczone według czterech różnych metod.
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Numerical simulation of laminate composite specimens failure
PublicationThis work presents some numerical results concerning simulation of failure of laminate composite specimens. In the article two tests to determine ultimate strength in an orthotropic layer, are considered: tension (TT1) and compression (TC1) test. The outcome is compared with experimental data provided by [9,10].
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A digital cartographic source for numerical models in hydrology
PublicationAutorzy prowadzą analizę wykorzystania i przydatności cyfrowych danych kartograficznych w rozwiązywaniu przestrzennych zagadnień hydrologicznych. Szczególne znaczenie dla prowadzonych analiz mają DTM i DEM. Są one źródłem bezpośrednich wielkości wejściowych modelu hydrologicznego i dodatkowo pozwalają na szersze możliwości prezentacji otrzymanego rozwiązania.
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Numerical modelling of DMT test in calibration chamber
PublicationAnaliza numeryczna badania DMT wykonanego w komorze kalibracyjnej w Katedrze Geotechniki Politechniki Gdańskiej. Badania przeprowadzono w piasku Lubiatowo średnio zagęszczonym i zagęszczonym przy składowej pionowej naprężenia 100 kPa. Modelowano proces wciskania ostrza dylatometru oraz fazę odkształcenia membrany. Analiza parametryczna uwzględnia wpływ wartości kąta tarcia wewnętrznego i dylatancji oraz modułu odkształcenia uzyskanych...
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An Experimental and Numerical Study of the Vortces Generated by Hydrofoils
PublicationArtykuł przedstawia wyniki projektu badawczego poświęconego wirom generowanym przez płaty nośne. W części eksperymentalnej wykonano anemometrem laserowym pomiary pól prędkości w poprzecznych przekrojach wirów. W częsci numerycznej przeprowadzono obliczenia używając różnych struktur siatki obliczeniowej i różnych modeli turbulencji. Na podstawie porównania wybrano model turbulencji i strukturę siatki najlepiej odzwieciedlające pole...
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An Experimental and Numerical Study of Tip Vortex Cavitation
PublicationArtykuł przedstawia eksperymentalne i numeryczne badanie kawitujacych wirów wierzchołkowych. Eksperymenty przeprowadzono w tunelu kawitacyjnym na modelu płata nośnego, wykonując pomiary pola prędkości wokół wiru przy pomocy metody Particle Image Velocimetry (PIV). Równolegle przeprowadzono numeryczne symulacje kawitującego wiru wierzchołkowego dla różnych parametrów przepływu. Symulacje wykonano programami Fluent i CFX, stosując...
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Numerical and Experimental Study of Tidal Turbine Performance
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Numerical and Experimental Study of Tidal Turbine Performance
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Numerical simulations of S700MC laser and hybrid welding
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Numerical Simulation of Duplex Steel Multipass Welding
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Numerical simulation of energy buoy motion in wave
PublicationW pracy przedstawiono opis numerycznej metody modelowania ruchu boi energetycznej na fali. Wyniki obliczeń porównano z wynikami otrzymanymi z badań modelowych przeprowadzonych w basenie hydromechanicznym.
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Numerical analysis of crack propagation in silicone nitride
PublicationThe properties of ceramics, specifically low density, high hardness, high temperature capability and low coefficient of thermal expansion are of most interest to rolling element manufacturers. The influence of ring crack size on rolling contact fatigue failure has been studied using numerical fracture analysis. Such cracks are very often found on ceramic bearing balls and decrease fatigue life rapidly. The numerical calculation...
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Numerical simulations of overflow experiments on a model dike
PublicationDike failure due to overtopping is one of the important factors, which should be considered in the dike designing process. Although the overflow is characterized by the relatively low risk of occurrence, in many cases dikes are totally destroyed or seriously damaged. An interesting phenomenon occurring during overflow is the trapping of air in pores of the unsaturated soil material. As the infiltration progresses from all sides,...
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Numerical Test for Stability Evaluation of Analog Circuits
PublicationIn this contribution, a new numerical test for the stability evaluation of analog circuits is presented. Usually, if an analog circuit is unstable then the roots of its characteristic equation are localized on the right half-plane of the Laplace s- plane. Because this region is unbounded, we employ the bilinear transformation to map it into the unit disc on the complex plane. Hence, the existence of any root inside the unit disc...
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Numerical-analytic methods for differential-algebraic systems
PublicationMetodę numeryczno-analityczną połączoną z metodą porównawczą zastosowano do układów równań różniczkowo-algebraicznych z linowymi warunkami brzegowymi otrzymując warunki dostateczne na istnienie rozwiązania. O prawych stronach zagadnienia zakładano warunek Lipschitza. Otrzymano oszacowania błędów. Problem z odchylonymi argumentami był również przedmiotem rozważań tej pracy.
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Numerical and Analytical Investigation of Aluminium Bracket Strengthening
PublicationThis paper focuses on an analytical and numerical investigation of aluminium brackets used to fasten light-weight curtain walls to building facilities. The authors propose a solution to increase the load capacity of aluminium brackets by means of additional cover plates (straps). This paper also includes a short survey of literature and material properties concerning the EN AW-6060 T6 aluminium alloy. This paper suggests an initiation...
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Monotone and numerical analytic- methods for differential equations.
PublicationPraca dotyczy problemu różniczkowo-całkowego (typu Fredholma) z ogólnym warunkiem początkowo-brzegowo-całkowym. W pierwszej części pracy, stosując metodę iteracji monotonicznych, sformułowano warunki dostateczne które gwarantują, że dyskutowany problem ma rozwiązanie ekstremalne w zbiorze generowanym przez dolne i górne rozwiązania. Rozważania teoretyczne poparto przykładem i dyskusją. W drugiej części pracy zastosowano metodę...
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On numerical calculation of acoustic field of plane source.
PublicationSkładowe harmoniczne wiązki akustycznej zostały obliczone na podstawie reprezentacji w postaci całek według teorii reprezentacji. Zastosowano nowe metody do obliczania całek od funkcji szybko oscylacyjnych.
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Numerical integration of a coupled Korteweg-deVries system
PublicationMetoda numeryczna została wprowadzona do rozwiązania ogólnych układów równańKorteweg´a- de Vries´a. Zastosowana do równania Hirota-Satsuma.
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A two-scale numerical approach to granular systems
PublicationW artykule zaprezentowano wyniki dwuskalowego numerycznego podejścia do materiałów granulowanych. Na poziomie mikro materiał był modelowany przy zastosowaniu metody elementów dyskretnych, natomiast na poziomie makro przy zastosowaniu metody elementów skończonych na bazie macierzy sztywności wyznaczonej na podstawie naprężeń i odkształceń na poziomie mikro.
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Application of the discrete Green's function-based antenna simulations for excitation of the total-field/scattered-field interface in the FDTD method
PublicationIn this article, the discrete Green's function formulation of the finite-difference time-domain (DGF-FDTD) method is proposed for simulation of wire antennas irradiating inhomogeneous dielectric scatterers. Surface equivalence theorem in the discrete domain is used to separate the problem into an inhomogeneous domain and a wire antenna that are simulated with the use of FDTD and DGF-FDTD, respectively. Then, the excitation of the...
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Comparison of Average Energy Slope Estimation Formulas for One-dimensional Steady Gradually Varied Flow
PublicationTo find the steady flow water surface profile, it is possible to use Bernoulli’s equation, which is a discrete form of the differential energy equation. Such an approach requires the average energy slope between cross-sections to be estimated. In the literature, many methods are proposed for estimating the average energy slope in this case, such as the arithmetic mean, resulting in the standard step method, the harmonic mean and...
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Damage detection in turbine wind blades by vibration based methods
PublicationThe paper describes results of numerical simulation for damage localization in the composite coat of a wind turbine blade usingmodal parameters and a modern damage detection method (wavelet transform).
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Metrological analysis of precision of the system of delivering a water capsule for explosive production of water aerosol
PublicationIn this paper an analysis of precision of the system controlling delivery by a helicopter of water-capsule designed for extinguishing large scale fires is presented. The analysis was performed using the numerical method of distribution propagation (Monte Carlo method) supplemented with results of application of the uncertainty propagation method. In addition the optimum conditions for the airdrop are determined to ensure achievement...
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Estimation of the uncertainty of the LEM CV 3-500 transducers processing function
PublicationThe paper presents the methodology for estimating uncertainty of a voltage transducer processing function based on the example of LEM CV 3-500 transducer. The analysis was performed using the method based on the GUM Guide propagation of uncertainty law and the Monte Carlo numerical method. The article also presents a comparative analysis of the results of a voltage measurement evaluation done using the Monte Carlo simulation method,...
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Diagonalized Macromodels in Finite Element Method for Fast Electromagnetic Analysis of Waveguide Components
PublicationA new technique of local model-order reduction (MOR) in 3-D finite element method (FEM) for frequency-domain electromagnetic analysis of waveguide components is proposed in this paper. It resolves the problem of increasing solution time of the reduced-order system assembled from macromodels created in the subdomains, into which an analyzed structure is partitioned. This problem becomes particularly relevant for growing size and...
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Portico Farmhouses of the Vistula Delta: Architecture, Current State and Finite Element Modelling of Timber Roof Truss under Material and Cross-section Uncertainty
PublicationThe article focuses on the oldest surviving I-type portico houses located in the Vistula Delta, which were built in the 17th and 18th centuries. The study describes the houses’ origins, structure, details of roof structures and technical condition, and it also includes numerical modelling of a roof truss and its mechanical analysis. Numerical models of the roof trusses are defined and analysed by means of the finite element method....
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A New Approach to Stability Evaluation of Digital Filters
PublicationIn this paper, a new numerical method of evaluating digital filter stability is presented. This approach is based on novel root-finding algorithms at the complex plane using the Delaunay triangulation and Cauchy's Argument Principle. The presented algorithm locates unstable zeros of the characteristic equation with their multiplicities. The proposed method is generic and can be applied to a vast range of systems. Verification of...
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Estimation of groundwater recharge in a shallow sandy aquifer using unsaturated zone modeling and water table fluctuation method
PublicationQuantification of groundwater recharge is one of the most important issues in hydrogeology, especially in view of the ongoing changes in climate and land use. In this study, we use numerical models of 1D vertical flow in the vadose zone and the water table fluctuation (WTF) analysis to investigate local-scale recharge of a shallow sandy aquifer in the Brda outwash plain in northern Poland. We show that these two methods can be...
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Jan Suchorzewski dr inż.
PeopleJan Suchorzewski MSc, born 13.03.1990 in Gdańsk, graduated in civil engineering with specialization in engineering structures at Gdańsk University of Technology in 2014, at thye same time begun work at GUT as PhD student working in a project "Analysis of coupled deterministic-statistic size effect in quasi-brittle materials" performing experimental investigation of shear strength of RC-beams and numerical calculations of concrete...
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Implementacja pomierzonych imperfekcji geometrycznych powłokicylindrycznej do modelu obliczeniowego
PublicationThis paper presents the method of implementation of the geometrical imperfections used by the author during the experimental and numerical research into the load-carrying capacity of cylindrical steel shells subjected to uniform circumferential compression.