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Search results for: NUMERICAL METHOD
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Advanced coating of interior of tanks for rising environmental safety - numerical simulation of grounding
PublicationZwiększanie bezpieczeństwa środowiska naturalnego podczas transportu materiałów ropopochodnych stale stanowi ważny i aktualny problem badawczy. W pracy prezentowane są wyniki badań innowacyjnych powłok ochronnych zmniejszających ryzyko rozlewu olejowego podczas kolizji środków transportu - w szczególności statków. Prace badawcze prowadzone były w ramach programu Eureka E!3614 CORET.
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Numerical Simulations of Seepage in Dikes Using unsaturated and Two-Phase Flow Models
PublicationModeling of water flow in variably saturated porous media, including flood dikes, is often based on the Richards equation, which neglects the flow of pore air, assuming that it remains at constant atmospheric pressure. However, there is also evidence that the air flow can be important, especially when the connectivity between the pore air and atmospheric air is lost. In such cases a full two-phase air-water flow model should be...
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COMPARATIVE ANALYSIS OF THE RESULTS OF GAS FLOW IN A LABYRINTH SEAL FOR A NUMERICAL AND THEORETICAL MODEL
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Numerical solution analysis of fractional point kinetics and heat exchange in nuclear reactor
PublicationThe paper presents the neutron point kinetics and heat exchange models for the nuclear reactor. The models consist of a nonlinear system of fractional ordinary differential and algebraic equations. Two numerical algorithms are used to solve them. The first algorithm is application of discrete Grünwald-Letnikov definition of the fractional derivative in the model. The second involves building an analog scheme in the FOMCON Toolbox...
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New Generation of Water lubricated Foil bearing - Numerical Models and Experimental Verification
PublicationIn the paper a new idea of foil water lubricated bearing and methodology of hydrodynamic characteristics calculations is presented. To assesses the theoretical characteristics of these bearings two different computer models were built. First is structural model coupled with fluid model. It takes into account: fluid flow in the deformed fluid gap, specific design of bearing support and friction in bearing support. The second is...
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Numerical study on seismic response of a base-isolated building modelled with shell elements
PublicationSeismic isolation is counted among the most popular and effective means of protecting structures against earthquake forces. Base isolators, like Lead-Rubber Bearings (LRB), High-Damping Rubber Bearings (HDB) or Friction Pendulum Systems (FPS) are extensively used in practice in many earthquake-prone regions of the world. The present paper reports the results obtained from the numerical study on seismic response of a base-isolated...
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EXPERIMENTAL AND NUMERICAL STUDY ON COLLISIONS BETWEEN STEEL STRUCTURES UNDER EARTHQUAKE EXCITATION
PublicationIn the time of high urbanization, the need to build closely-spaced structures forces the designers to take into account earthquake-induced collisions between adjacent buildings and their effects on the response of structures. Past and recent investigations confirmed that interactions between adjacent buildings during earthquakes may cause serious damages to the structural elements and may even lead to total collapse of the structure....
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Earthquake–induced pounding on response of adjacent structures in series: experimental and numerical study
PublicationPounding between structures in series during earthquakes may cause serious damage in the structur-al 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 called "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 study on pounding between two adjacent buildings under earthquake excitation
PublicationSeismic excitation, which results in large horizontal relative displacements, may cause collisions between two adjacent structures due to insufficient separation distance between them. Such collisions, known as earthquake-induced structural pounding, may induce severe damages. In this paper, the case of pounding between two adjacent buildings is studied by the application of single degree-of-freedom structural models. Impact is...
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Turbulence model evaluation for numerical modelling of turbulent flow and heat transfer of nanofluids
PublicationIn this work, Nusselt number and friction factor are calculated numerically for turbulent pipe flow (Reynolds number between 6000 and 12000) with constant heat flux boundary condition using nanofluids. The nanofluid is modelled with the single-phase approach and the simulation results are compared with experimental data. Ethylene glycol and water, 60:40 EG/W mass ratio, as base fluid and SiO2 nanoparticles are used as nanofluid...
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Numerical modeling of the combustion in a lab-scale pulverized-coal fired combustion chamber
PublicationThis work presents results of numerical modeling of the combustion process inside a lab-scale drop-tube chamber, designed to investigate the slagging properties of the flue ashes, created through the solid fuel firing. Interaction between turbulence and chemistry is accounted by use of probability density function (PDF). FLUENT inputs for non-premixed combustion chemistry modeling are defined. A discrete second phase of the coal...
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Numerical and experimental investigation of thermal convection near electric devices with vertical channels
PublicationThis paper presents the results of numerical and experimental investigation of thermal convection near heat emitting surfaces of an electric device. For the intensification of thermal convection, special vertical channels were formed near the heat emitting surfaces of the device. An experimental test has proved that there is an optimal length of the channels – thermal convection is the most intensive then. Air velocity vectors...
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On numerical analysis of a thin-walled I-beam with warping stiffenes undertorsional loads
PublicationPraca jest streszczeniem referatu wygłoszonego na międzynarodowej konferencji Metody Komputerowe w Mechanice, Wisła, 3-6 czerwca 2003. Przedstawiono problem numerycznej analizy belek cienkościennych ze stężeniami. Omówiono dwa modele jednowymiarowe: jeden bazujący na koncepcji skupionej sztywności bimomentowej, a drugi na zastosowaniu superelementu MES. Otrzymane wyniki porównano z rezultatami analizy MES przy zastosowaniu dyskretyzacji...
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Numerical analysis of a test embankment on soft ground using an anisotropic model with destructuration
PublicationPrzeprowadzono analizę numeryczną konsolidacji podłoża słabonośnego pod obciążeniem próbnego nasypu drogowego metodą elementów skończonych. Zachowanie się gruntu słabonośnego zamodelowano przy użyciu nowego modelu konstytutywnego typu multi-laminate uwzględniającego anizotropię wytrzymałości oraz zjawisko destrukturyzacji. Wyniki obliczeń porównano z pomiarami polowymi.
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Some remarks about numerical stability in nonlinear dynamics on the basic of truss structures.
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Numerical simulation of damage detection in rectangular plate by two-dimensional wavelet transform.
PublicationW pracy przedstawiono metodę lokalizacji pęknięć w płytach przy zastosowaniu transformaty falkowej.
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The computer numerical control system with permanent magnet synchronous motor servo-drives.
PublicationPrzedstawiono układ serwonapędów wieloosiowej maszyny sterowanej numerycznie. W układzie wykorzystano silniki synchroniczne z magnesami trwałymi oraz procesory synałowe DSP. Omówiono algorytmy sterowania nadrzędnego oraz problemy sterownia silnika PMSM.
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Numerical simulations of transverse pounding-involved response of buildings due to earthquake excitation.
PublicationCelem artykułu jest analiza (w kierunku poprzecznym) zachowania się uderzających o siebie budynków podczas trzęsienia ziemi. W analizie tej obie konstrukcje modelowane są przy użyciu dyskretnego, sprężysto-plastycznego modelu o skupionych masach, zaś do symulacji zderzeń zastosowano nieliniowy model lepko-sprężysty. Wyniki analizy pokazują, iż zderzanie prowadzi do znacznego wzrostu odpowiedzi w kierunku poprzecznym dla konstrukcji...
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Numerical calculation of three-phase transformer's residual flux in ATP and PSpice programs.
PublicationW artykule przedstawiono analizę przebiegów prądu i strumienia magnetycznego podczas wyłączania transformatora energetycznego, wykonaną w celu określenia strumieni szczątkowych. Wykorzystano do tego celu modele obwodowe zbudowane w oparciu o programy symulacyjne ATP (Alternative Transients Program) i PSpice. Wyniki obliczeń okazały się bardzo zbliżone dla obu modeli. Przy ich wykorzystaniu obliczono strumienie szczątkowe w kolumnach...
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Numerical Modeling and Simulation of Vehicular Crashes into Three-Bar Metal Bridge Rail
PublicationAdvanced finite element (FE) modeling and simulations were performed on vehicular crashes into a three-bar metal bridge rail (TMBR). The FE models of a sedan, a pickup truck, and a TMBR section were adopted in the crash simulations subject to Manual for Assessing Safety Hardware (MASH) Test Level 2 (TL-2) and Test Level 3 (TL-3) requirements. The test vehicle models were first validated using full-scale physical crash tests conducted...
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Flow through a prosthetic mechanical aortic valve: Numerical model and experimental study
PublicationThis research presents a numerical model dedicated for virtual patient diagnostics in the field of synthetic valve implantation. The model operates based on computational fluid dynamics solver with implemented rigid body motion solver. Characteristic indicators related to the prosthetic valve were determined to assess the correctness of cardiac system operation after implantation. A novel approach for dynamic time discretization...
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Statistical description and numerical calculations of cylindrical vertical tanks with initial geometric imperfections
PublicationDokonano identyfikacji rzeczywistych wstępnych imperfekcji geometrycznych stalowych pionowych zbiorników walcowych. Imperfekcje przedstawiono jako pole losowe opisane za pomocą odpowiednio dobranej funkcji korelacyjnej, wartości oczekiwanej oraz obwiedni pola. Wykorzystując własne programy numeryczne przeprowadzono generację zbioru odchyłek geometrycznych zbiornika. Porównano estymatory wygenerowanego pola losowego z parametrami...
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Detection of defects in PMMA beam using shear waves - numerical simulation and experiment
PublicationTest doświadczalny falami sprężystymi jest częścią systemu diagnostycznego belek. Autorzy badają pole przyspieszeń wywołane przepływem fal ultradźwiękowych i jego modyfikacje wynikające z wprowadzonych uszkodzeń belki. Artykuł porównuje wyniki eksperymentalne z symulacjami numerycznymi MES. The experimental test introduced in the paper is the part of the diagnostic system utilizing the elastic waves. The authors investigate the...
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Comparative Analysis of Numerical and Experimental Studies of the Airflow Around the Sample of Urban Development
PublicationIn this paper, on the background of a short overview of the recent advances in the field of Environmental Wind Engineering (EWE), a comparison of wind tunnel experiment and numerical simulation for some cases of airflow around an urban layout have been reported. The purpose of the study is quantitative and qualitative comparison of measurements in the wind tunnel as well as numerical simulation using Ansys Fluent software. The...
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Numerical analysis of lumbar spine injury during road safety barrier collision
PublicationPurpose: Enhancing road safety is a critical goal worldwide, necessitating the development of clear standards for road safety systems. This study focuses on lumbar spine (L-spine) compression injuries during collisions with concrete road safety barriers (RSBs). It aims to analyze internal forces during impact to understand L-spine injury biomechanics in such accidents. Methods: The research included a literature review, analyzing...
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Numerical Analysis of Turbulent Flow over a Backward-facing Step in an Open Channel
PublicationComputational examinations of the flow field in an open channel having a single Backward--Facing Step (BFS) with a constant water depth of 1.5 m were performed. The effects of the expansion ratio, and the flow velocity along the reattachment length, were investigated by employing two different expansion ratios of 1.5 and 2, and eight various flow velocities of 0.5, 1, 2, 3, 4, 5, 7.5 and 10 m/sec in the Computational Fluid Dynamic...
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Experimental and Numerical Analysis of Air Trapping in a Porous Medium with Coarse Textured Inclusions
PublicationThe paper presents a 2D upward infiltration experiment performed on a model porous medium consisting of fine sand background with two inclusions made of coarser sands. The purpose of the experiment was to investigate the effects of structural air trapping, which occurs during infiltration as a result of heterogeneous material structure. The experiment shows that a significant amount of air becomes trapped in each of the inclusions. Numerical...
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Experimental and numerical investigations on RC beams with stirrups scaled along height or length.
PublicationBelki żelbetowe (RC) ze zbrojeniem poprzecznym (strzemiona) poddane czteropunktowemu zginaniu zostały zbadane eksperymentalnie i numerycznie. Belki były skalowane wzdłuż wysokości lub długości. Były przezbrojone, aby uniknąć płynięcia zbrojenia podłużnego. W pierwszej kolejności przeprowadzono badania laboratoryjne na belkach żelbetowych ze strzemionami. Ze względu na brak podobieństwa geometrycznego zaobserwowano dwa odrębne tryby...
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Numerical investigations of effect of indoor air quality on thermal comfort in residential buildings.
PublicationArtykuł przedstawia wyniki numeryczne MES odnośnie wpływu koncentracji CO2 w lokalnej strefie powietrza w budynkach mieszkalnych naturalnie wentylowanych na zachowanie mieszkańców. Obliczenia wykonano w 2 wymiarach. Zbadano wpływ położenia mieszkańców i prędkości wchodzącego powietrza.
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Direct spectrum detection based on Bayesian approach
PublicationThe paper investigates the Bayesian framework's performance for a direct detection of spectrum parameters from the compressive measurements. The reconstruction signal stage is eliminated in by the Bayesian Compressive Sensing algorithm, which causes that the computational complexity and processing time are extremely reduced. The computational efficiency of the presented procedure is significantly...
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Global Complex Roots and Poles Finding Algorithm Based on Phase Analysis for Propagation and Radiation Problems
PublicationA flexible and effective algorithm for complex roots and poles finding is presented. A wide class of analytic functions can be analyzed, and any arbitrarily shaped search region can be considered. The method is very simple and intuitive. It is based on sampling a function at the nodes of a regular mesh, and on the analysis of the function phase. As a result, a set of candidate regions is created and then the roots/poles are verified...
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On the convergence of a nonlinear finite-difference discretization of the generalized Burgers–Fisher equation
PublicationIn this note, we establish analytically the convergence of a nonlinear finite-difference discretization of the generalized Burgers-Fisher equation. The existence and uniqueness of positive, bounded and monotone solutions for this scheme was recently established in [J. Diff. Eq. Appl. 19, 1907{1920 (2014)]. In the present work, we prove additionally that the method is convergent of order one in time, and of order two in space. Some...
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Testing of low temperature behaviour of asphalt mixtures in bending creep test
PublicationThe paper presents a method of bending beam test and its importance for evaluation of asphalt mixtures behaviour at low temperatures. Two types of asphalt mixtures: asphalt concrete AC with normal paving grade bitumen and stone mastic asphalt SMA with SBS-modified bitumen were tested. Long-term oven ageing (LTOA) test was also used in the laboratory according to SHRP procedure. The Burgers model was applied and rheological parameters...
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Validation Process for Computational Model of Full-Scale Segment for Design of Composite Footbridge
PublicationExperimental tests and numerical simulations of a full-scale segment of a foot and cycle bridge made of polymer composites are presented in the paper. The analysed structure is made of sandwich panels, which consist of glass fibre reinforced polymer (GFRP) multi-layered laminate faces and a PET foam (obtained from recycling) core. The dimensions of the segment cross-section are the same as for the target footbridge; however, span...
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Simulations of hydro-fracking in rock mass at meso-scale using fully coupled DEM/CFD approach
PublicationThe paper deals with two-dimensional (2D) numerical modelling of hydro-fracking (hydraulic fracturing) in rocks at the meso-scale. A numerical model was developed to characterize the properties of fluid-driven fractures in rocks by combining the discrete element method (DEM) with computational fluid dynamics (CFD). The mechanical behaviour of the rock matrix was simulated with DEM and the behaviour of the fracturing fluid flow...
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Axial capacity of steel built-up battened columns
PublicationThis paper deals with the numerical investigation aimed to study the axial capacity of pin-ended steel built-up columns. Three methods of calculating forces in chords and batten, taking into account the material and geometric imperfections specified in the Eurocode 3 are considered. The aim of this study was to compare different methods allowing the calculation of the column load capacity and determine a simpler and faster method...
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Optimization of Stabilizing Systems in Protection of Cultural Heritage: The Case of the Historical Retaining Wall in the Wisłoujście Fortress
PublicationThe aim of the paper is to propose new quantitative criteria for selecting the optimal method of securing and repairing a historical object, which take into account Structural, Conservation and Architectural aspects (the S–C–A method). Construction works on cultural heritage sites tend to be challenging and require an interdisciplinary approach. Therefore, they are strictly related to the philosophy of sustainable development which...
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Towards application of uncertainty quantification procedure combined with experimental procedure for assessment of the accuracy of the DEM approach dedicated for granular flow modeling
PublicationThere is a high demand for accurate and fast numerical models for dense granular flows found in many industrial applications. Nevertheless, before numerical model can be used its need to be always validated against experimental data. During the validation, it is important to consider how the measurement data sets, as well as the numerical models, are affected by errors and uncertainties. In this study, the uncertainty quantification...
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On some problems in determining tensile parameters of concrete model from size effect tests
PublicationThe paper presents results of numerical simulations of size effect phenomenon in concrete specimens. The behaviour of in-plane geometrically similar notched and unnotched beams under three-point bending is investigated. In total 18 beams are analysed. Concrete beams of four different sizes and five different notch to depth ratios are simulated. Two methods are applied to describe cracks. First, an elasto-plastic constitutive law...
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O obliczaniu kablobetonowych ciągłych dźwigarów mostowych
PublicationPrzedstawiono analityczną metodę obliczania kablobetonowych ciągłych dźwigarów z wykorzystaniem metody sił. Podano przykład analizy zrealizowanego kablobetonowego wiaduktu o schemacie dwuprzęsłowej belki ciągłej. Porównano wyniki obliczeń analitycznych i numerycznych (model belkowy, program Sofistik).
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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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Hybrid technique for the analysis of circular waveguide junctions loaded with ferrite posts
PublicationThis study presents a hybrid technique for the analysis of circular waveguide junctions loaded with axially symmetrical ferrite posts of irregular shape. The method is based on a combination of the finite-difference frequency- domain technique with a mode-matching technique. The proposed approach is validated by comparing the presented results with numerical ones obtained from commercial software. The application of a cylindrical...
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Finite element simulation of cross shaped window panel supports
PublicationThe aim of the work is to verify suitability of cross-shaped window panel supports for mullion-transom wall systems. The Finite Element Method (FEM) is chosen to determine the behaviour of stainless steel elements under loading. The advanced non-linear numerical simulations are carried out using an implicit FEM software package MSC.Marc. This study is proposed to initiate the comprehensive investigation of mechanical properties...
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Wybrane problemy plastyczności w płaskim ośrodku mikropolarnym
PublicationW pracy analizuje się sprężysto-plastyczny płaski ośrodek mikropolarny. Do rozwiązań równań plastyczności wykorzystuje się technikę Closest Point Projection Method. Przedstawiono przykład numeryczny w płaskim stanie naprężenia, zasygnalizowano problem lokalizacji w zadaniach z osłabieniem materiału.
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Finite Element Approaches to Model Electromechanical, Periodic Beams
PublicationPeriodic structures have some interesting properties, of which the most evident is the presence of band gaps in their frequency spectra. Nowadays, modern technology allows to design dedicated structures of specific features. From the literature arises that it is possible to construct active periodic structures of desired dynamic properties. It can be considered that this may extend the scope of application of such structures. Therefore,...
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Probabilistic sensitivity of limit states of structures : The Monte Carlo simulation
PublicationThe main issue of the paper is the probabilistic sensitivity of the limit states of structures with respect to selected input design variables. Attempt to the problem is done by the dedicated Monte Carlo simulation procedure. Basic design variables are random variables of given probability distributions, presented in the form of random numbers. Uni-parametrical increment of the dominant basic variable (basic variables) is done,...
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The impact of the shape of deep drilled well screen openings on the filtration process in full saturation conditions
PublicationThe authors propose a supplementary method of modelling seepage flow around the deep drilled well screen. The study applies 3D numerical modelling (FEM) in order to provide an in-depth analysis of the seepage process. The analysis of filtration parameters (flow distribution q(x,t) and pressure distribution p) was conducted using the ZSoil.PC software system. The analysis indicates that the shape of perforation is of secondary importance...
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Modeling of Passive and Forced Convection Heat Transfer in Channels with Rib Turbulators
PublicationThe main goal of the research presented in this paper was the experimental and numerical analysis of heat enhancement and aerodynamic phenomena during air flow in a channel equipped with flow turbulators in the form of properly configured ribs. The use of ribs intensifies the heat transfer and at the same time increases not only the flow resistance but also the energy costs. Therefore, designing modern heat exchangers with optimal...
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Identification of Parameters Influencing the Accuracy of the Solution of the Nonlinear Muskingum Equation
PublicationTwo nonlinear versions of the Muskingum equation are considered. The difference between both equations relates to the exponent parameter. In the first version, commonly used in hydrology, this parameter is considered as free, while in the second version, it takes a value resulting from the kinematic wave theory. Consequently, the first version of the equation is dimensionally inconsistent, whereas the proposed second one is consistent. It...
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Analysis of Failure Mechanism in Joints with Positive Eccentricity in CFS Truss
PublicationThe paper presents studies concerning the load-bearing capacity of truss joints with a positive eccentricity resulting from the arrangement of geometric members and the failure mechanisms observed in the joints. Based on the previously conducted experimental study, a numerical model of the tested fragment of the CFS truss with eccentricity in the joint was created and validated. All structural details of the tested truss and the...