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Wyniki wyszukiwania dla: FUNCTIONALLY GRADED MATERIAL
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Representation of magnetic hysteresis in single-phase transformer for circuit simulations
PublikacjaThe paper presents a mathematical model for the hysteresis phenomenon in a multi-winding single-phase core type transformer. In the circuit transformer model, it is assumed that there is a flux common Φ to all windings as nonlinear and hysteretic function of the total currents Θ (Ampere turns) of all windings. To simulate magnetic behaviour of the iron core the feedback scalar Preisach model of hysteresis is developed. The Preisach...
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Rapid dimension scaling of triple-band antennas by means of inverse surrogate modeling
PublikacjaGeometry scaling of antennas, i.e., finding optimum dimensions of the structure for given operating conditions and material parameters is an important yet challenging problem. In this paper, we discuss fast dimension scaling of triple-band antennas with respect to operating frequencies. We adopt the inverse surrogate modeling approach where the surrogate model is a function of the three operating frequencies of the antenna and...
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Stability of a truss under upward wind loading
PublikacjaThe present paper is devoted to the numerical investigations of stability of a truss under upward wind load. The truss is braced at its the upper cord. A structural variant including lateral braces, or lateral and torsional braces is considered. The research presents the problems of linear buckling and non-linear static analysis of the truss shell and beam model with geometric and material non-linearity are presented. The initial...
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Study on 19th-century cast iron columns from the former financial office building in Kwidzyn
PublikacjaThe article presents the results for cast iron columns used as floor supports in the former financial office building in Kwidzyn (Poland).The stocktaking drawings provided the general and detailed data about the 19th century designer’s decisions. During the research, architectural and structural analysis was carried out. The graphics were used as a starting material for preparing 3D calculation models. The FEM-based numerical simulations...
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The porosity and morphology of PU foams prepared by solvent casting/salt leaching method with different solvents
PublikacjaIn this study, the polyurethane (PU) system based on poly(ethylene-butylene) adipate diol, 1,6-hexamethylene diisocyanate, 1,4-butanediol and ascorbic acid is used to prepare a foamed material. Polymer foams were created using solvent casting/salt-particle leaching (SC/PL) method. The influence of the PU concentration in different solutions [either in a DMF or in DMF with THF as a co-solvent] on the morphology and porosity of the...
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Properties of Nasicon-based CO2 sensors with Bi8Nb2O17 reference electrode
PublikacjaPotentiometric CO2 sensors based on Nasicon (Na+ conductor, Na3Zr2Si2PO12) electrolyte, Bi8Nb2O17/Pt reference electrode and different sensing electrodes have been prepared. Besides the sensing electrode material, sensors differ from each other in the reference electrode preparation technique. The main aim of this study is to investigate sensor construction and electrode fabrication process influence on sensor properties. The optimal...
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SIMULATIONS OF FRACTURE IN CONCRETE BEAMS UNDER BENDING USING A CONTINUUM AND DISCRETE APPROACH
PublikacjaThe paper describes two-dimensional meso-scale results of fracture in notched concrete beams under bending. Concrete was modelled as a random heterogeneous 4-phase material composed of aggregate particles, cement matrix, interfacial transitional zones and air voids. Within continuum mechanics, the simulations were carried out with the finite element method based on a isotropic damage constitutive model enhanced by a characteristic...
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Overview of planar antenna loading metamaterials for gain performance enhancement: the two decades of progress
PublikacjaMetamaterials (MTMs) are artificially engineered materials with unique electromagnetic properties not occurring in natural materials. MTMs have gained considerable attention owing to their exotic electromagnetic characteristics such as negative permittivity and permeability, thereby a negative refraction index. These extraordinary properties enable many practical applications such as super-lenses, and cloaking technology, and are...
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Challenges in operating and testing loop heat pipes in 500–700 K temperature ranges
PublikacjaThe potential applications of loop heat pipes (LHPs) are the nuclear power space systems, fuel cell thermal management systems, waste heat recovery systems, medium temperature electronic systems, medium temperature military systems, among others. Such applications usually operate in temperature ranges between 500–700 K, hence it is necessary to develop an LHP system that will meet this requirement. Such a thermal management device...
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Rapid tolerance‐aware design of miniaturized microwave passives by means of confined‐domain surrogates
PublikacjaThe effects of uncertainties, primarily manufacturing tolerances but also incomplete information about operating conditions or material parameters, can be detrimental to the performance of microwave components. Quantification of such effects is essential to ensure a meaningful evaluation of the structure, in particular, its reliability under imperfect fabrication procedures. The improvement of the circuit robustness can be achieved...
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Prediction of maximum tensile stress in plain-weave composite laminates with interacting holes via stacked machine learning algorithms: A comparative study
PublikacjaPlain weave composite is a long-lasting type of fabric composite that is stable enough when being handled. Open-hole composites have been widely used in industry, though they have weak structural performance and complex design processes. An extensive number of material/geometry parameters have been utilized for designing these composites, thereby an efficient computational tool is essential for that purpose. Different Machine Learning...
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Influence of the boron doping level on the electrochemical oxidation of raw landfill leachates: advanced pre-treatment prior to the biological nitrogen removal
PublikacjaThe electrochemical oxidative treatment of landfill leachates (LLs) containing high amounts of ammonia nitrogen and organic matter was used as a promising method, prior to biological processes, to achieve the final effluent quality that would be acceptable by current regulations. The deposited boron-doped diamond electrodes (BDDs) with different boron doping concentrations (10000, 5000 and 500 ppm of B) were applied as anodes....
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Nieliniowa statyka 6-parametrowych powłok sprężysto plastycznych. Efektywne obliczenia MES
PublikacjaGłównym zagadnieniem omawianym w monografii jest sformułowanie sprężysto-plastycznego prawa konstytutywnego w nieliniowej 6-parametrowej teorii powłok. Wyróżnikiem tej teorii jest występujący w niej w naturalny sposób tzw. stopień 6 swobody, czyli owinięcie (drilling rotation). Podstawowe założenie pracy to przyjęcie płaskiego stanu naprężenia uogólnionego na ośrodek typu Cosseratów. Takie podejście stanowi oryginalny aspekt opracowania....
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INFLUENCE OF SOLID PARTICLE CONTAMINATION ON THE WEAR PROCESS IN WATER LUBRICATED MARINE STRUT BEARINGS WITH NBR AND PTFE BUSHES
PublikacjaThis paper reports on a study of the influence of solid particle contamination on the wear process in water-lubricated slide bearings (steel-acrylonitrile-butadiene rubber (NBR) and steel- polytetrafluoroethylene (PTFE)). To compare the wear of the shaft journal and bushes (NBR and PTFE) when lubricated with fresh water and contaminated water, an experiment was carried out to identify key factors that influence the state of wear...
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Effect of Tube Bundle Arrangement on the Performance of PCM Heat Storage Units
PublikacjaThe results of comprehensive study on charging and discharging of latent heat storage systems (LHSS) are presented. The multi tube shell-and-tube unit with a variable layouts of the tube bundles are examined. Two tube arrangements – in-line and staggered are tested. A variable number of tubes and different tube positions in a bundle are investigated. Moreover, two pitch ratios are studied. Three commercially available substances...
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On the exact equilibrium conditions of irregular shells reinforced by beams along the junctions
PublikacjaThe exact, resultant equilibrium conditions for irregular shells reinforced by beams along the junctions are formulated. The equilibrium conditions are derived by performing direct integration of the global equilibrium conditions of continuum mechanics. New, exact resultant static continuity conditions along the singular curve modelling reinforced junction are presented. The results do not depend on shell thickness, internal through-the-thickness...
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Power converter interface for urban DC traction substations - solutions and functionality.
PublikacjaThis paper focuses on extending an urban DC traction substation functionality by means of an additional power converter interface (PCI). In particular, by enabling bidirectional energy exchange between LV DC traction grid, AC grid and V2G chargers. Among other things, the presented material compares general attributes of the most promising DC/DC converters that can be used in a PCI, meet the requirements of galvanic isolation and...
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The importance and availability of marine certified reference materials
PublikacjaTraceability and reliable results are the two pillars of analytical methods; certified reference materials (CRMs) meet this requirement. ISO 17034:2016 credentials provide brief information on general requirements for the competence of Reference Material Producers (RMPs). The different types of CRMs have been produced in recent years for chemical analysis in food, water, soil, and sediment matrices in recent years. This review...
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Measurements of the optical and thermal properties of the 2D black phosphorus coating
PublikacjaBlack phosphorus is a 2D material, which properties are still being discovered. In this paper, the sensitivity to the temperature of a few-layer black phosphorus coating deposited, on the surface of a microsphere-based fiber-optic sensor, by a dip-coating method is presented. The coating was investigated after 2, 3, and 5 deposition cycles and during temperature growth from 50 °C to 300 °C in an interferometric setup. The intensity...
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Mid-infrared spectroscopy for characterization of Baltic amber (succinite)
PublikacjaNatural Baltic amber (succinite) is the most appreciated fossil resin of the rich cultural traditions dating back to prehistoric times. Its unequivocal identification is extremely important in many branches of science and trades including archeology, paleontology, chemistry and finally mineralogical and gemological societies. Current methods of modification of natural succinite are more and more sophisticated making the identification...
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Authentication of whisky due to its botanical origin and way of production by instrumental analysis and multivariate classification methods
PublikacjaHeadspacemass-spectrometry (HS-MS), mid infrared (MIR) and UV–vis spectroscopywere used to authenticate whisky samples from different origins and ways of production ((Irish, Spanish, Bourbon, TennesseeWhisky and Scotch). The collected spectra were processed with partial least-squares discriminant analysis (PLS-DA) to build the classification models. In all cases the five groups ofwhiskieswere distinguished, but the best resultswere...
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Polaron hopping conduction in manganese borosilicate glass
PublikacjaA study on a novel material - manganese borosilicate glass without alkali metals, was reported. It was found that the obtained samples containing high amount of manganese oxide (60MnO–xSiO2–(40 − x)B2O3, x = 5, 10, 15, 20 and 30 mol%) were amorphous and homogeneous. XPS measurements showed that most of manganese ions are at oxidation level of Mn2 + ions and the mean oxidation level slightly moves toward higher value, with increasing...
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Experimental study of pressure rise at the evaporator of capillary pumped loop with acetone and water as working fluids
PublikacjaIn this work studied is the possibility of fluid pumping using capillary forces in the capillary pumped loop. Experimental and theoretical studies have been performed to understand the phenomena associated with heat transfer in porous structure of the evaporator. The capillary effect was studied during operation of two different capillary porous structures with two different working fluids, namely water and acetone. The results...
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The life cycle cost of a building from the point of view of environmental criteria of selecting the most beneficial offer in the area of competitive tendering
PublikacjaThe article analyses environmental and ecological criteria of selecting the most beneficial offer in the aspect of LCC. Construction works contracts and the potential method of defining the above criteria, among others, is pondered on (for example by the recommendation of a material, which is supposed to be used, a ban on substances that are harmful for human health as well for the environment). In the relation to the above, it...
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GaN Nanowire Array for Charge Transfer in Hybrid GaN/P3HT:PC71BM Photovoltaic Heterostructure Fabricated on Silicon
PublikacjaAbstract: We demonstrate that a GaN nanowire array can be used for efficient charge transfer between the organic photovoltaic layer and silicon in a Si/GaN/P3HT:PC71BM inverted hybrid heterostructure. The band alignment of such a material combination is favorable to facilitate exciton dissociation, carrier separation and electron transport into Si. The ordered nature of the GaN array helps to mitigate the intrinsic performance...
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Disturbances of Earth magnetic field caused by eddy currents of airplane
PublikacjaThe uniform magnetic field of the Earth in the surrounding of a mobile, metallic object undergoes deformation by eddy currents. The influence of the moving, conducting object on the Earth's total magnetic field depends on the object's shape, position and speed of the changes relative to the magnetic field vector of the Earth, as well as the electric conductivity and the relative magnetic permeability of the material. Disturbances...
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Objectivization of audio-video correlation assessment experiments
PublikacjaThe purpose of this paper is to present a new method of conducting an audio-visual correlation analysis employing a head-motion-free gaze tracking system. First, a review of related works in the domain of sound and vision correlation is presented. Then assumptions concerning audio-visual scene creation are shortly described. The objectivization process of carrying out correlation tests employing gaze-tracking system is outlined....
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Factors Shaping the Working Environment, Living Conditions and Recreation on Board Ship
PublikacjaA seagoing ship is a working place, an accommodation space and a recreation area at the same time. Being exposed to harsh physical conditions, it must satisfy different requirements. The human organism and its qualities become a point of reference here; consequently, the functions and spatial arrangement and interiors of a ship must be subordinated to its needs. The organisation of the space in contemporary ships meant for human...
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Nonprotein nitrogenous compounds
PublikacjaThe non-protein nitrogen (NPN) fraction is an important group of food components for both technological and nutritional reasons. Free amino acids (FAAs), oligopeptides, amines, nucleic acids, and nucleotides, as well as other low-molecular nitrogen-containing components (cyanogenic glycosides, alkaloids, thiazoles, oxazoles, pyrroles, and pyrazines), are found in most foods. Their content depends on many factors, starting from...
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Structural Health Monitoring of Composite Shell Footbridge for Its Design Validation
PublikacjaThe paper presents the structural health monitoring system of the composite bridge for pedestrians and cyclists. The footbridge was designed and manufactured within the FOBRIDGE project. It is the first bridge in the world, which is classified as a consistent single element structural girder, made of sandwich shells, entirely produced in a single cycle. The developed structural health monitoring system, supported design process,...
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Pylon foundation of a cable stayed bridge at the motorway ring road of Wrocław
PublikacjaThe largest bridge of the motorway ring road of Wroclaw is a cable stayed bridge over the Odra river near Rędzin. Due to hydrogeological conditions of the ground it was not convenient to use standard bored piles of high length. Instead shorter piles were applied with additional improvement by cement injections at the pile toes. This decision was possible by extending ground investigation program and application of numerical modeling...
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Optimization of chip removing system operation in circular sawing machine
PublikacjaThe paper presents the optimization of the wood chips removing system in the sliding table saw. Chips are generated during the cutting of the material. The attention was focused on the upper casing of mentioned system. The methodical experimental studies of the pressure distribution inside the casing during the wood chip removing operation for the selected rotational speed of saw blade with a diameter of 300 mm and 450 mm were...
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Local buckling of compressed flange of cold-formed channel members made of aluminum alloy
PublikacjaThe paper deals with local buckling of a compressed single flange of thin-walled channel cold- formed columns and beams made of aluminum alloy. Material is described by means of the Ramberg-Osgood constitutive equation. Axial compression of the columns and beams undergoing bending is taken into consid- eration. A simple model of the member flange in the form a long beam elastically connected to the web is used to find the critical...
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A method to assess transverse vibration energy of ship propeller shaft for diagnostic purposes
PublikacjaThe article discusses a key problem of ship propulsion system vibration diagnostics, which concerns assessing this part of mechanical energy transmitted from the main engine to the ship propeller which is dissipated due to propeller shaft vibration. A simplified calculation model is proposed which allows the total energy of the generated torsional vibration to be assessed from the shaft deflection amplitude measured at the mind-span...
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Flexural buckling and post-buckling of columns made of aluminium alloy
PublikacjaThe paper concerns flexural buckling and initial post-buckling of axially compressed columns made of aluminium alloy described by the Ramberg-Osgood relationship. The non-linear differential equation of the problem is derived using the stationary total energy principle and the assumptions of classical beam theory within a finite range. The approximate analytical solution of the equation leading to the buckling loads and initial...
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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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Quantitative assessment
PublikacjaThe main trends in the development of analytical chemistry are the determination of increasingly lower concentrations of analytes in samples with complex matrix composition (trace analysis). While the obtained analytical results must be reliable, which means that they must accurately (truly and precisely) reflect the actual content of analytes in a representative sample of the material object under study. However, it is an extremely...
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Influence of steel brackets supporting crane runway girders structure on the stress distribution in the brackets
PublikacjaThe paper presents a numerical analysis of steel brackets supporting a double-span crane runway girders. The purpose of the study was to assess the new structural solution based on the stress distribution in the brackets. In order to simplify the connection, the bottom flange of the crane runway girder is based directly on the upper flange of the bracket. As a result, the support reaction is no longer applied in the plane of the...
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Rheology of polymer blends
PublikacjaPolymer blends are physical mixtures of two or more homopolymers or copolymers. This type of materials have wide spectrum of technological applications, and their properties are influenced, e.g., by the properties of single components and morphology of final material. The rheology of polymer blends is connected with the processing of polymer blends and is influenced by thermodynamics, morphology, and their evolution during testing....
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Influence of Phase Composition on Dielectric Properties of Bismuth-Based Ceramics with Scheelite-Type Structure
PublikacjaGoal of the present research was to study dielectric properties of BiNbO4 ceramics fabricated by solid state reaction route followed with pressureless sintering. The samples were fabricated from the mixture of oxides, viz. Nb2O5 and Bi2O3. Apart from stoichiometric amount an excess of 3%, 5% and 10% by mole of Bi2O3 was used. It was found that an excess amount of Bi2O3 oxide caused formation of Bi5Nb3O15 minor phase in amount of...
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Buckling and initial post-local buckling behaviour of cold-formed channel member flange
PublikacjaThe initial post-buckling behaviour of a cold-formed channel member flange after its local buckling is investigated. An axially compressed column or beam subjected to pure bending is considered. The member material is assumed to follow a linear stress-strain relationship. The governing non-linear differential equation of the problem is derived using the minimum total potential energy principle. An approximate solution for the equation...
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Importance of Specific Heat Characterization when Reporting New Superconductors: An Example of Superconductivity in LiGa2Rh
PublikacjaWe show that the full-Heusler compound LiGa2Rh is a superconductor with Tc = 2.4 K. The new superconductor was found as a result of an intuition-based extension of a database search for superconductors that looked for the presence of peaks in the electronic band structure near the Fermi energy. The measurement of the entropy loss during the transition from the nonsuperconducting to the superconducting state, a straightforward measurement...
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Sensitivity analysis of flexural and torsional buckling loads of laminated columns
PublikacjaThe paper concerns first order sensitivity analysis of flexural and torsional bucklin g loads of axiallycompressed thin-walled columns with bisymmetric or axisymmetric cross-section made of unidirectional fibre-reinforcedlaminate. The first variation of critical loads versus some variations of the column material properties and cross-sectionaldimensions is derived. Numerical examples dealing with simply supported I-columns are...
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Substrate Dependence in the Formation of Au Nanoislands for Plasmonic Platform Application
PublikacjaIn this work, the influence of the various substrates on Au nanoisland formation has been studied. Nanostructures were obtained via annealing of thin Au films. In order to determine nanoisland formation mechanisms, correlation between an initial film thickness and temperature of formation, shapes, and dimensions of nanostructures was examined. For the surface morphology studies, nanograin structure, and chemical composition analysis,...
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Analysis of EN 1993-1-6 guidelines about determining amplitudes of equivalent imperfections of steel cylindrical shells subjected to uniform external pressure
PublikacjaCivil engineering structures should be designed with reference to relevant standards. One of them is a Eurocode 3 standard EN 1993-1-6:2007: Design of steel structures Part 1-6: Strength and Stability of Shell Structures. According to this standard, the value of buckling load can be determined using different approaches: classical hand calculations (stress design) and geometrical and material non-linear analysis of an imperfect...
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Rigid polyurethane foams modified with ground tire rubber - mechanical, morphological and thermal studies
PublikacjaRigid polyurethane foams, prepared by a single step method, were modified with the two types of ground tire rubber particles, i.e. untreated and thermo-mechanically reclaimed by using a co-rotating twin screw extruder. The foaming process as well as the structure and the physical, mechanical and thermal properties of the resulting foams were investigated. The presence of ground tire rubber decreased the velocity of polymerization....
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Controling w zarządzaniu bezpieczeństwem pracy
PublikacjaW artykule przedstawiono możliwość wykorzystania controllingu do badania zagrożeń w procesie pracy. Dla oceny rozwiązań usprawniających wprowadzono pojęcie oszczędności zasobu typu praca i typu materiał, zużywanych w procesie realizacji zadań wytwórczych. Artykuł podkreśla możliwość osiągania efektów ekonomicznych (ograniczenia kosztów) w wyniku poprawy warunków pracy.CONTROLLING IN WORK SAFETY MANAGEMENTThe article presents the...
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Buckling analyses of metal cylindrical silos containing bulk solids during filling
PublikacjaThe paper presents 3D results on stability of thin-walled cylindrical metal silos made of isotropic rolled and corrugated plates containing bulk solids. The behavior of bulk solids was described using a hypoplastic constitutive model. Nonlinear finite element (FE) analyses with both geometric and material nonlinearity were performed with a perfect and an imperfect silo shell wherein initial geometric imperfections were taken into...
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MODELLING OF CONCRETE FRACTURE AT AGGREGATE LEVEL USING DEM BASED ON X-RAY mu CT IMAGES OF INTERNAL STRUCTURE
PublikacjaThe paper describes two-dimensional meso-scale numerical results of fracture in notched concrete beams under quasi-static three-point bending. Concrete was modelled as a random heterogeneous 4-phase material composed of aggregate particles, cement matrix, interfacial transitional zones (ITZs) and air voids. As a numerical approach, the discrete element method (DEM) was used. The concrete micro-structure in calculations was directly...
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Mesoscopic simulations of crack propagation in concrete using cohesive elements
PublikacjaThe paper presents results of two-and three-dimensional meso-scale simulations of fracture in notched concrete beams subjected to three-point bending test. Concrete was assumed as a 3-phase material composed of aggregate grains placed in the cement matrix with Interfacial Transitional Zones (ITZs) between then. In 2D simulations macro-voids were also taken into account. The particle distribution was taken from real concrete beams...