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Wyniki wyszukiwania dla: BOUNDARY ELEMENT ANALYSIS
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The hydrodynamic pressure field of the ship Zodiak, measurements and calculations
PublikacjaThe article presents the results of measurements of the slowly changing hydrodynamic pressure field HPF generated by the movement of the ship, Zodiak, in the Bay of Gdansk. The measurement results have been obtained in the framework of the program of the work in Siramis, under the auspices of the European Defence Administration of the EU, by the research team of the Naval Academy in Gdynia. The measurement results were compared with...
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Fluid–solid interaction on a thin platelet with high-velocity flow: vibration modelling and experiment
PublikacjaThe paper concerns the nonlinear behaviour of a thin platelet that is streamlined in an aerodynamic tunnel. The air velocity in the aerodynamic tunnel was at 858.9 km/h or 0.7 Ma (Ma—Mach number is a dimensionless quantity in fluid dynamics representing the ratio of flow velocity past a boundary to the local speed of sound). This experiment was numerically simulated using FSI (fluid–solid interaction) tools, namely the coupling...
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Improved finite element method for flow, heat and solute transport of Prandtl liquid via heated plate
PublikacjaIn the current study, a vertical, 3D-heated plate is used to replicate the generation of heat energy and concentration into Prandtl liquid. We discuss how Dufour and Soret theories relate to the equations for concentration and energy. In order to see how efectively particles, interact with heat and a solvent, hybrid nanoparticles are used. It does away with the phenomena of viscous dissipation and changing magnetic felds. The motivation...
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Buckling Analysis of a Micro Composite Plate with Nano Coating Based on the Modified Couple Stress Theory
PublikacjaThe present study investigates the buckling of a thick sandwich plate under the biaxial non-uniform compression using the modified couple stress theory with various boundary conditions. For this purpose, the top and bottom faces are orthotropic graphene sheets and for the central core the isotropic soft materials are investigated. The simplified first order shear deformation theory (S-FSDT) is employed and the governing differential...
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Analysis of ship's magnetic field with consideration of inner ferromagnetic devices
PublikacjaThis paper presents computer simulations of ship’s magnetic signatures. The influence of ship’s inner ferromagnetic devices on the signature was presented. The magnetic fields of the ship’s model were calculated in Opera 3D 18R2. The model was built from thin plates. The new, thin plate boundary condition was introduced on all ship’s surfaces.
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Analysis of hydrodynamic pressure fields of motorboats and pontoons in shallow water
PublikacjaThe article presents the results of calculations of the pressure fields generated by a motorboat at the bottom of a shallow sea. Calculations were made using the boundary elements method (BEM), arranged on the surface of the boat and the bottom of the sea. This method is described in [3], and applied on a free surface linearized boundary condition. Results for four different lengths of motorboats, from 2.85 m to 9.5 m, sea depth...
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Evaluation of the Effectiveness of Methods for Delimitation of the Boundaries of Registered Parcels in the Process of Modernization of Land and Building Registration
PublikacjaIn the article, a comparative analysis of two methods for delimitation of the boundaries of registered parcels was carried out: the method of direct measurement in the field and the photogrammetric method. One of the analyzed factors was the attendance of parcels’ owners during the development of boundary recognition agreements. Research has shown that in this aspect the method of direct measurement...
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Thermal and hydraulic phenomena in boundary layer of minijets impingement on curved surfaces
PublikacjaPresented work considers flow and thermal phenomena occurring during the single minijet impingement on curved surfaces, heated with a constant heat flux, as well as the array of minijets. Numerical analyses, based on the mass, momentum and energy conservation laws, were conducted, regarding single phase and two-phase simulations. Focus was placed on the proper model construction, in which turbulence and boundary layer modeling...
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Analytical predictions for the buckling of a nanoplate subjected to non-uniform compression based on the four-variable plate theory
PublikacjaIn the present study, the buckling analysis of the rectangular nanoplate under biaxial non-uniform compression using the modified couple stress continuum theory with various boundary conditions has been considered. The simplified first order shear deformation theory (S-FSDT) has been employed and the governing differential equations have been obtained using the Hamilton’s principle. An analytical approach has been applied to obtain...
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Propagation in the Open Cylindrical Guide of Arbitrary Cross Section With the Use of Field Matching Method
PublikacjaA simple solution to propagation problem in open waveguides and dielectric fibers of arbitrary convex cross section is presented. The idea of the analysis is based on the direct field matching technique involving the usage of the field projection at the boundary on a fixed set of orthogonal basis functions. A complex root tracing algorithm is utilized to find the propagation coefficients of the investigated guides. Different convex...
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Influence of anisotropic stiffness in numerical analyses of tunneling and excavation problems in stiff soils
PublikacjaIn the stiff overconsolidated soil deposits anisotropy influences small and intermediate strain stiffness and hence it has important impact on the results of discplacement preditcions in soil-structure modelling. The authors developed a cross-anisotropic soil model which combines both stress dependent and micro-structural anisotropy. The model is based on the anisotropic hyperelastic kernel for small strain stiffness. Reference...
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Mechanical and Microstructural Characterization of TIG Welded Dissimilar Joints between 304L Austenitic Stainless Steel and Incoloy 800HT Nickel Alloy
PublikacjaIn this article, the mechanical properties and microstructure of 304L austenitic stainless steel/Incoloy 800HT nickel alloy dissimilar welded joints are investigated. The joints were made of 21.3 mm × 7.47 mm tubes using the TIG process with the use of S Ni 6082 nickel filler metal. No welding imperfections were found and high strength properties of joints were obtained, meeting the assumed acceptance criteria of the product’s...
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Weighted difference schemes for systems of quasilinear first order partial functional differential equations
PublikacjaThe paper deals with initial boundary value problems of the Dirichlet type for system of quasilinear functional differential equations. We investigate weighted difference methods for these problems. A complete convergence analysis of the considered difference methods is given. Nonlinear estimates of the Perron type with respect to functional variables for given functions are assumed. The proof of the stability of difference problems...
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Blade Section Prpfile Array Lifting Surface Design Method for Marine Screw Propeller Blade
PublikacjaThe lifting surface model is widely used in screw propeller design and analysis applications. It serves as a reliable tool for determination of the propeller blade mean line and pitch distribution. The main idea of this application was to determine the blade shape that would satisfy the kinematic boundary condition on its surface with the prescribed bound circulation distribution over it. In this paper a simplified lifting surface...
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Heat transfer intensification by jet impingement – numerical analysis using RANS approach
PublikacjaJet impingement is a method of the heat transfer enhancement applied in the engineering systems. The idea is to generate fast-flow fluid jet which impinge on the heated (or cooled) surface, causing significantly higher heat transfer rate. Although some flat surface jet impingement cases are described in the literature, the validated data is still limited. The reason is coming from the fact, that these flows are hydrodynamically...
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Thermal Buckling Analysis of Circular Bilayer Graphene sheets Resting on an Elastic Matrix Based on Nonlocal Continuum Mechanics
PublikacjaIn this article, the thermal buckling behavior of orthotropic circular bilayer graphene sheets embedded in the Winkler–Pasternak elastic medium is scrutinized. Using the nonlocal elasticity theory, the bilayer graphene sheets are modeled as a nonlocal double–layered plate that contains small scale effects and van der Waals (vdW) interaction forces. The vdW interaction forces between the layers are simulated as a set of linear springs...
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CLASSIFICATION OF RESTRAINTS IN THE OPTIMIZATION PROBLEM OF A COLD-FORMED PROFILE
PublikacjaThis work describes the restraints in the optimization problem. This is an important and complicated issue because it requires taking into account a vast range of information related to the design and production. In order to describe the relations of a specific optimization problem, it is essential to adopt appropriate criteria and to collect information on all kinds of restraints, i.e. boundary conditions. The following paper...
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Anti-plane waves in an elastic thin strip with surface energy
PublikacjaWe consider anti-plane motions of an elastic plate taking into account surface energy within the linear Gurtin–Murdoch surface elasticity. Two boundary-value problems are considered that describe complete shear dynamics of a plate with free faces or with free and clamped faces, respectively. These problems correspond to anti-plane dynamics of an elastic film perfectly or non-perfectly attached to a rigid substrate. Detailed analysis...
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Paintings
PublikacjaThe painting as a curtain (...) A contradiction is therefore what constitutes a painting, and ambiguity is its right. As a young artist, I intuitively defined the work of art as a boundary. Over the years that intuition changed into a conviction that the particular form of art which is painting at the same time reveals and hides; it exists at this intersection of functions as a see-through curtain. We don’t know why there are some...
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Four-node semi-EAS element in six-field nonlineartheory of shells
PublikacjaW pracy sformułowano 4-węzłowy powłokowy element skończony dla konstrukcji powłokowych. Element opracowano w ramach nieliniowej 6-parametrowej teorii powłok z niesymetrycznymi miarami odkształceń membranowych. Kinematyka powłoki jest opisana przez dwa pola: translacji i obrotów, przy czym wszystkie trzy parametry obrotu traktowane są jako niezależne. W wyniku tego sformułowany element nadaje się do analizy struktur powłokowych...
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Adaptation of the arbitrary Lagrange–Euler approach to fluid–solid interaction on an example of high velocity flow over thin platelet
PublikacjaThe aim of this study is to analyse the behaviour of a thin plate with air flow velocities of 0.3–0.9 Ma. Data from the experiment and numerical tools were used for the analysis. For fluid–solid interaction calculations, the arbitrary Lagrange–Euler approach was used. The results of the measurements are twofold. The first one is the measurement of the flow before and after vibrating plate, i.e. pure flow plate, and the second consists...
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On the influence of a surface roughness on propagation of anti-plane short-length localized waves in a medium with surface coating
PublikacjaWe discuss the propagation of localized surface waves in the framework of the linear Gurtin–Murdoch surface elasticity and taking into account a roughness of a free boundary. We derive a boundary-value problem for anti-plane motions with curvilinear boundary and surface stresses. Using the asymptotic technique developed earlier, we obtain the form of a localized wave and analyze its amplitude evolution. As the main result we present...
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Numerical Simulations of Seepage in Dikes Using unsaturated and Two-Phase Flow Models
PublikacjaModeling 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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Electro-thermal buckling of elastically supported double-layered piezoelectric nanoplates affected by an external electric voltage
PublikacjaPurpose Thermal buckling of double-layered piezoelectric nanoplates has been analyzed by applying an external electric voltage on the nanoplates. The paper aims to discuss this issue. Design/methodology/approach Double-layered nanoplates are connected to each other by considering linear van der Waals forces. Nanoplates are placed on a polymer matrix. A comprehensive thermal stress function is used for investigating thermal buckling....
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INNOVATIVE THERMODYNAMICAL CYCLES BASED ON ENHANCEMENT MASS, MOMENTUM, ENTROPY AND ELECTRICITY TRANSPORT DUE TO SLIP, MOBILITY, TRANSPIRATION, ENTROPY AND ELECTRIC JUMPS AS WELL AS OTHER NANO-FLOWS PHENOMENA
PublikacjaIn our work, a further development of the authors model of thermo-chemical flow of fuel, air, oxygen, steam water, species, ionic and electron currents within nano channels and nano-structures of novel devices is presented. Different transport enhancement models are taken into account -among them the most important are: the velocity slip connected with complex external friction, the Darcy mobility and the Reynolds transpiration....
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Subcritical bifurcation of free elastic shell of biological cluster
PublikacjaIn this paper we will investigate symmetry-breaking bifurcation of equilibrium forms of biological cluster. A biological cluster is a two-dimensional analogue of a gas balloon. The cluster boundary is connected with its kernel by elastic links. The inside part is filled with compressed gas or fluid. Equilibrium forms of biological cluster can be found as solutions of a certain second order ordinary functional-differential equation...
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Pre-oxidation of porous ferritic Fe22Cr alloys for lifespan extension at high-temperature
PublikacjaPre-oxidation of porous ferritic Fe22Cr alloys was extensively studied in this paper. Weight gain measurements and SEM analysis revealed that pre-oxidation performed at 900◦C for 40 min increased the lifespan of the alloy. A Cr evaporation study did not disclose any significant influence of the pre-oxidation process on the Cr content in the alloy. For a more detailed assessment, TEM imaging and X-ray tomography measurements of...
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Characterization of Bi6Fe2Ti3O18 Ceramics with Impedance Spectroscopy
PublikacjaIn the present research the tool of impedance spectroscopy was utilized to characterize dielectric behavior of Aurivillius-type ceramics of Bi6Fe2Ti3O18 composition fabricated by hot pressing method from the stoichiometric mixture of oxides Bi2O3, TiO2 and Fe2O3. Impedance spectroscopy was applied to characterize dielectric response of bulk, grain boundary, and material/electrode interfaces of the fabricated polycrystalline ceramic...
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Exact resultant equilibrium conditions in the non-linear theory of branching and self-intersecting shells
PublikacjaWe formulate the exact, resultant equilibrium conditions for the non-linear theory of branching and self-intersecting shells. The conditions are derived by performing direct through-the-thickness integration in the global equilibrium conditions of continuum mechanics. At each regular internal and boundary point of the base surface our exact, local equilibrium equations and dynamic boundary conditions are equivalent, as expected,...
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On Von Karman Equations and the Buckling of a Thin Circular Elastic Plate
PublikacjaWe shall be concerned with the buckling of a thin circular elastic plate simply supported along a boundary, subjected to a radial compressive load uniformly distributed along its boundary. One of the main engineering concerns is to reduce deformations of plate structures. It is well known that von Karman equations provide an established model that describes nonlinear deformations of elastic plates. Our approach to study plate deformations...
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The Dynamical Projectors Method Hydro and Electrodynamics
PublikacjaThe dynamical projectors method proves to reduce a multicomponent problem to the simplest one-component problem with its solution determined by specific initial or boundary conditions. Its universality and application in many different physical problems make it particularly useful in hydrodynamics, electrodynamics, plasma physics, and boundary layer problems. A great variety of underlying mechanisms are included making this book...
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Numerical analysis of vacuum drying of a porous body in the integrated domain
Publikacjan the present study, the vacuum drying process of an apple slice is numerically modeled based on a control volume method. Transient two-dimensional Navier– Stokes, energy, moisture, and Luikov equations are solved by numerical coding (Fortran) to simulate the simultaneous heat and mass transfer in the ambient and apple slice, respectively. The privilege of using Luikov's model is that the capillary forces are considered, and a...
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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
PublikacjaThe 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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Modelling of elastic wave propagation in a bolted joint using a thin layer of shell elements
PublikacjaThere are many mathematical models describing the propagation of elastic waves through the imperfect boundary of two media. They were successfully applied to modelling of high frequency bulk waves and their interaction with local defects. On the other hand, the existing literature models of bolted connections ignore the aspect of imperfect connection between elements. Therefore, this paper presents the concept of application of...
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Fractional problems with advanced arguments
PublikacjaThis paper concerns boundary fractional differential problems with advanced arguments. We investigate the existence of initial value problems when the initial point is given at the end point of an interval. Nonhomogeneous linear fractional differential equations are also studied. The existence of solutions for fractional differential equations with advanced arguments and with boundary value problems has been investigated by using...
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On topology optimization of large deformation contact-aided shape morphing compliant mechanisms
PublikacjaA topology optimization approach for designing large deformation contact-aided shape morphing compliant mechanisms is presented. Such mechanisms can be used in varying operating conditions. Design domains are described by regular hexagonal elements. Negative circular masks are employed to perform dual task, i.e., to decide material states of each element and also, to generate rigid contact surfaces. Each mask is characterized by...
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Strongly anisotropic surface elasticity and antiplane surface waves
PublikacjaWithin the new model of surface elasticity, the propagation of anti-plane surface waves is discussed. For the proposed model, the surface strain energy depends on surface stretching and on changing of curvature along a preferred direction. From the continuum mechanics point of view, the model describes finite deformations of an elastic solid with an elastic membrane attached on its boundary reinforced by a family of aligned elastic...
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GPR investigation of the strengthening system of a historic masonry tower
PublikacjaIn this paper the condition assessment of the strengthening system of a masonry tower was carried out by the GPR method. The study provided unique experimental data acquired during measurements of the reinforced concrete frame embedded in masonry walls. Conducted numerical and experimental investigations were focused on the phenomenon of the diffraction-refraction scattering of the electromagnetic energy. A hyperbola resulting...
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Analysis of the Water Level Variation in the Polish Part of the Vistula Lagoon (Baltic Sea) and Estimation of Water Inflow and Outflow Transport through the Strait of Baltiysk in the Years 2008–2017
PublikacjaThe Vistula Lagoon is located in both Poland and Russia along the southern coast of the Baltic Sea. It is connected to the Baltic Sea in the Russian part by the Strait of Baltiysk. The purpose of the paper is to identify the dominant factors underlying the water level variation mechanism at Tolkmicko in the Vistula Lagoon, revealed by a statistical analysis of the measured data and a discussion on the inflow and outflow transport...
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Thermal Analysis Of Hybrid Microchannel-Microjet Heat Exchanger
PublikacjaThe paper presents the numerical investigation of a microjet- microchannel cooling module. In which microjets of water are impinging into the microchannels and forming a liquid film on the impingement surface. Applied technology takes benefits from two very attractive heat removal techniques. When laminar jets are impinging on the surface have a very high kinetic energy at the stagnation point, also in microchannels boundary layer...
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Analysis of the image force effects on the recombination at the donor-acceptor interface in organic bulk heterojunction solar cells
PublikacjaWe consider the influence of image force effects on the recombination at the donor-acceptor interface in organic bulk heterojunction solar cells. The conclusion is that the charge carriers of one sign located in the material with lower permittivity recombine at the boundary between donor and acceptor phases. This process competes with the recombination of opposite sign charge carriers, leading to the reduction of the Langevin-type...
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Some aspects of noise generated by a small ship in the shallow sea
PublikacjaThe passing and underwater moving objects produce the noises of variable intensity, which significantly increase the overall level of noise in the sea. This applies to both the sonic and ultrasonic range. The excessive levels of underwater noise adversely affects the so-called underwater acoustic climate and is the reason why this phenomenon is intensively investigated from the number of years. The results of experimental work...
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NUMERICAL MODELLING AND EXPERIMENTATION OF HISTORICAL CARPENTRY CORNER LOG JOINTS
PublikacjaThe main purpose of this research is to determine the stress distributions on the contact surfaces between the logs of the historical carpentry corner joints. The additional purpose is to compare the stress distribution for four different boundary conditions in the case of dry and wet pine wood. The paper presents the results of numerical analysis of the shortcorner dovetail connection and the saddle notch corner joint, which are...
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On the generalized model of shell structures with functional cross-sections
PublikacjaIn the present study, a single general formulation has been presented for the analysis of various shell-shaped structures. The proposed model is comprehensive and a variety of theories can be used based on it. The cross-section of the shell structure can be arbitrarily analyzed with the presented equations. In other words, various types of shell structures, including cylindrical, conical, spherical, elliptical, hyperbolic, parabolic,...
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On the Buckling Response of Axially Pressurized Nanotubes Based on a Novel Nonlocal Beam Theory
PublikacjaIn the present study, the buckling analysis of single-walled carbon nanotubes (SWCNT) on the basis of a new refined beam theory is analyzed. The SWCNT is modeled as an elastic beam subjected to unidirectional compressive loads. To achieve this aim, the new proposed beam theory has only one unknown variable which leads to one equation similar to Euler beam theory and is also free from any shear correction factors. The equilibrium...
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An optimal sliding mode control based on immune-wavelet algorithm for underwater robotic manipulator
PublikacjaIn this paper, a robust optimal Sliding Mode Controller (SMC) based on new algorithm of Artificial Immune System (AIS) is proposed for trajectory tracking of underwater manipulators. A new AIS algorithm is used to derive optimal values of surface parameters and boundary layer thickness in SMC with considering minimum torques and error. Surface parameters and boundary layer thickness are considered as antibody in AIS and Morlet...
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Bernstein-type theorem for ϕ-Laplacian
PublikacjaIn this paper we obtain a solution to the second-order boundary value problem of the form \frac{d}{dt}\varPhi'(\dot{u})=f(t,u,\dot{u}), t\in [0,1], u\colon \mathbb {R}\to \mathbb {R} with Sturm–Liouville boundary conditions, where \varPhi\colon \mathbb {R}\to \mathbb {R} is a strictly convex, differentiable function and f\colon[0,1]\times \mathbb {R}\times \mathbb {R}\to \mathbb {R} is continuous and satisfies a suitable growth...
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THERMAL ANALYSIS AND DESIGN OF HYBRID MICROCHANNEL-MICROJET TEST PROBE
PublikacjaThe paper presents the numerical investigation of a microjet- microchannel cooling module. In which microjets of water are impinging into the microchannels and forming a liquid film on the impingement surface. Applied technology takes benefits from two very attractive heat removal techniques. When lminar jets are impinging on the surface have a very high kinetic energy at the stagnation point, also in microchannels boundary layer...
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Non-standard contact conditions in generalized continua: microblock contact model for a Cosserat body
PublikacjaGeneralized continuum theories involve non-standard boundary conditions that are associated with the additional kinematic variables introduced in those theories, e.g., higher gradients of the displacement field or additional kinematic degrees of freedom. Accordingly, formulation of a contact problem for such a continuum necessarily requires that adequate contact conditions are formulated for the additional kinematic variables and/or...
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Projektowanie układów ramowych z zastosowaniem analizy wrażliwości
PublikacjaW pracy przedstawiono przykład projektowania układów ramowych z zastosowaniem analizy wrażliwości. Rozważane układy ramowe rozwiązano autorskim programem napisanym w środowisku MATLAB, metodą elementów skończonych. Badano wpływ zmiany modułu Younga oraz wpływ zmiany wielkości przekroju poprzecznego na wybrane przemieszczenia ramy. Przedstawiono wyniki dla analizy wrażliwości jedno i wieloparametrycznej.