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Wyniki wyszukiwania dla: THERMAL BEHAVIOUR
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Three dimensional simulations of FRC beams and panels with explicit definition of fibres-concrete interaction
PublikacjaHigh performance concrete (HPC) is a quite novel material which has been rapidly developed in the last few decades. It exhibits superior mechanical properties and durability comparing to normal concrete. HPC can achieve also superior tensile performance if strong fibres (steel or carbon) are implemented in the matrix. Thus, there exist the unabated interest in studying how the addition of different types of fibres modifies the...
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Pawlak's flow graph extensions for video surveillance systems
PublikacjaThe idea of the Pawlak's flow graphs is applicable to many problems in various fields related to decision algorithms or data mining. The flow graphs can be used also in the video surveillance systems. Especially in distributed multi-camera systems which are problematic to be handled by human operators because of their limited perception. In such systems automated video analysis needs to be implemented. Important part of this analysis...
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Experimental comparison of hydrodynamic thrust bearings with different pad surface materials
PublikacjaBabbitt is the material most frequently used as the pad surface material for hydrodynamic bearings operating at usual operating conditions. It shows many advantages important for safe bearing operation, as for example: low friction coefficient, corrosion resistance, fair mechanical properties and outstanding conformability. On the other hand, it is not free from disadvantages, such as limited fatigue strength or limited resistance...
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Experimental and numerical investigations of ultimate strength of degradated structures
PublikacjaThe presented work investigates the corrosion influence on the structural behaviour of structural elements. Nine welded large-scale stiffened plates, and 30 standard small specimens have been subjected to the accelerated marine immersed conditions. After corrosion testing, the specimens have been accurately measured in terms of surface characteristics. The coupon specimens were furtherly subjected to tensile loading to develop...
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The impact of institutions on innovation networks: empirical evidence from Poland
PublikacjaInnovation networks may accelerate and improve the innovation process, while institutional pathologies may hamper it. This study employs the Kruskal-Wallis H test and regression analysis to determine if the relationship between institutions and innovation networks does exist among the investigated variables. The purpose of the study was to find out whether cooperation with special local institutions influences the innovative behaviour...
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Performance Characteristics of a Micro-turbine, International
Publikacja. In the paper a design of a multi-stage micro-turbine with partial admission of all the stages is described in detail and the results of particular experimental investigations and numerical calculations are shown, followed by conclusions. The co-generative micro-power plant with the HFE7100 as a working medium was designed and built for experimental investigations. The values of the main cycle parameters were as follows:- heat...
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Surface sliding in human abdominal wall numerical models: Comparison of single-surface and multi-surface composites
PublikacjaDetermining mechanical properties of abdominal soft tissues requires a coupled experimental-numerical study, but first an appropriate numerical model needs to be built. Precise modeling of human abdominal wall mechanics is difficult because of its complicated multi-layer composition and large variation between specimens. There are several approaches concerning simplification of numerical models, but it is unclear how far one could...
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A framework for detection of selfishness in multihop mobile ad hoc networks
PublikacjaThe paper discusses the need for a fully-distributed selfishness detection mechanism dedicated for multihop wireless ad hoc networks which nodes may exhibit selfish forwarding behaviour. The main contribution of this paper is an introduction to a novel approach for detecting and coping with the selfish nodes. Paper describes a new framework based on Dempster-Shafer Theory called Dempster-Shafer Theory-based Selfishness Detection...
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Differential analysis of dynamic immittance spectra
PublikacjaThis work presents a new approach to the analysis of immittance spectrograms of systems characterised by non-stationarity. The possibility of linking the evolution of the immittance response with changes in the parameters describing the system is achieved by introducing a spectrum in differential form. By using the above procedure, it becomes possible to separate elements with a dependence (or lack thereof) from an independent...
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Agent-based social network as a simulation of a market behaviour
PublikacjaRecent years and the outbreak of world's economic crisis in 2008 proved the crucial importance of reliable analysis of market dynamics. However, werarely apply models of proper detail level (the global prosperity forecast of 2007 can be seen as a grim proof). The behaviour of individuals and companies is far from being ideal and rational. Many claims that the economic paradigm of rational expectations (coming from J. Muth and R....
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Local buckling and initial post-buckling behaviour of channel member flange - analytical approach
PublikacjaThe local buckling and initial post-buckling behaviour of the cold-formed channel member flange is investigated. The governing nonlinear differential equation for axially compressed columns and beams undergoing pure bending is derived using the stationary total potential energy principle. The critical stress and initial post-buckling equilibrium path is determined by means of a perturbation approach. The results obtained allow...
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Experimental tests for the determination of mechanical properties of PVC foil
PublikacjaThe paper presents an application of the PVC film in civil engineering. Mechanical behaviour of the PVC film applied for suspended ceilings, in the form of a stretch ceiling is investigated under uniaxial and biaxial tensile tests. The study is focused on the determination of mechanical properties from experimental data (uniaxial and biaxial tensile tests). The uniaxial cyclic tests are performed in order to observe a variation...
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Geometrically nonlinear FEM analysis of 6-parameter resultant shell theory based on 2-D Cosserat constitutive model
PublikacjaWe develop the elastic constitutive law for the resultant statically and kinematically exact, nonlinear, 6-parameter shell theory. The Cosserat plane stress equations are integrated through-the- thickness under assumption of the Reissner-Mindlin kinematics. The resulting constitutive equations for stress resultant and couple resultants are expressed in terms of two micropolar constants: the micropolar modulus Gc and the micropolar...
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Adding Intelligence to Cars Using the Neural Knowledge DNA
PublikacjaIn this paper we propose a Neural Knowledge DNA based framework that is capable of learning from the car’s daily operation. The Neural Knowledge DNA is a novel knowledge representation and reasoning approach designed to support discovering, storing, reusing, improving, and sharing knowledge among machines and computing devices. We examine our framework for drivers' classification based on their driving behaviour. The experimental...
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Indirect control over subordinate units
PublikacjaDeveloping a game universe usually involves creation of various units which can be both, encountered by a player or controlled by him. There is a number of works considering autonomous behaviours of units wandering around the game world. When it comes to the units controlled by the player, they often are lack of autonomy and are strictly controlled by the player. This paper presents a concept of units behaviour depending on their...
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OPTICAL STRAIN MEASUREMENT OF CONCRETE VERSUS MANUAL EXTENSOMETER MEASUREMENT BASED ON THE TEST RC DEEP BEAM IN A COMPLEX STATE OF STRESS
PublikacjaThe purpose of this study is to compare the strain measurement techniques of concrete in R-C element subjected to the monotonic load up to the failure. In the analysis manual extensometer methods of measurements and the optical system ARAMIS for non-contact three-dimensional measurements of deformation was used. The test sample was a cantilever deep beam loaded throughout the depth which was a part of the reinforced concrete deep...
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MACHINE VISION DETECTION OF THE CIRCULAR SAW VIBRATIONS
PublikacjaDynamical properties of rotating circular saw blades are crucial for both production quality and personnel safety. This paper presents a novel method for monitoring circular saw vibrations and deviations. A machine vision system uses a camera and a laser line projected on the saw’s surface to estimate vibration range. Changes of the dynamic behaviour of the saw were measured as a function of the rotational speed. The critical rotational...
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Influence of the notch rounding radius on estimating the elastic notch stress concentration factor in a laser welded tee joint
PublikacjaIn recent years an increased interest of industry in sandwich-type metal structures can be observed. These structures consist of thin plates of 2.5 mm in thickness separated by stiffeners of different shapes and forms. Welds joining the plates and stiffeners are made on the outer side of the plates using laser welding technique. A locally focused source of heat causes the plate to melt creating a very narrow and elongated joint....
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Surface Treatment of Rubber Waste
PublikacjaThis chapter deals with the study of different approaches to improve the compatibility of waste rubber with polymeric matrixes of high density polyethylene (HDPE) by using surface treatments to increase adhesion. Different surface treatments such as etching with sulphuric and nitric acids, the use of a silane as a coupling agent and chlorination with trichloroisocyanuric acid (TCI) have been applied. The modification of waste rubber...
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Advancing the evidence base for public policies impacting on dietary behaviour, physical activity and sedentary behaviour in Europe: The Policy Evaluation Network promoting a multidisciplinary approach
PublikacjaNon-communicable diseases (NCDs) are the leading cause of global mortality. As the social and economic costs of NCDs have escalated, action is needed to tackle important causes of many NCD’s: low physical activity levels and unhealthy dietary behaviours. As these behaviours are driven by upstream factors, successful policy interventions are required that encourage healthy dietary behaviours, improve physical activity levels and...
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Influence of heterogeneous air entry pressure on large scale unsaturated flow in porous media
PublikacjaThe paper presents numerical simulations of water infiltration in unsaturated porous media containing coarse-textured inclusions embed- ded in fine-textured background material. The calculations are performed using the two-phase model for water and air flow and a simplified model known as the Richards equation. It is shown that the Richards equation cannot correctly describe flow in the presence of heterogeneities. How- ever, its...
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Spike patterns and chaos in a map-based neuron model
PublikacjaThe work studies the well-known map-based model of neuronal dynamics introduced in 2007 by Courbage, Nekorkin and Vdovin, important due to various medical applications. We also review and extend some of the existing results concerning β-transformations and (expanding) Lorenz mappings. Then we apply them for deducing important properties of spike-trains generated by the CNV model and explain their implications for neuron behaviour....
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Multidisciplinary approach to the assessment of historic structures based on the case of a masonry bridge in Galicia (Spain)
PublikacjaThe paper presents a general method to evaluate a masonry structure with a complex geometry and unknown material properties. This multidisciplinary approach integrates close range digital photogrammetry,ground probing radar (GPR) and finite elements analysis (FEM) to analyse a masonry bridge. The resulting information from photogrammetry and radar is applied to define a 3D model, which is then used to simulate the behaviour of...
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Comparison of anti-plane surface waves in strain-gradient materials and materials with surface stresses
PublikacjaHere we discuss the similarities and differences in anti-plane surface wave propagation in an elastic half-space within the framework of the theories of Gurtin–Murdoch surface elasticity and Toupin–Mindlin strain-gradient elasticity. The qualitative behaviour of the dispersion curves and the decay of the obtained solutions are quite similar. On the other hand, we show that the solutions relating to the surface elasticity model...
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Modeling of Combined Phenomena Affecting an AUV Stealth Vehicle
PublikacjaIn the paper some results of research connected with modelling the basic stealth characteristics of an AUV vehicle are presented. First of all a general approach to design of the stealth AUV autonomous underwater vehicle under consideration is introduced. Then, the AUV stealth vehicle concept is briefly described. Next a method of modelling of the stealth characteristics is briefly described as well. As an example of the stealth...
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Power Hardware-in-the-Loop Approach In Power System Development
PublikacjaThe main objective of the research is the verification of the Power Hardware-In-The-Loop (PHIL) approach in power system analysis and design. The premise of the article is that using PHIL approach the performance of the power system in steady and transient state conditions can be analysed in real power system conditions. Models of induction machine were developed and real time simulations were performed. Simulation variables were...
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Mathematical analysis of a generalised p53-Mdm2 protein gene expression model
PublikacjaWe propose the generalisation of the p53-Mdm2 protein gene expression model introduced by Monk (2003). We investigate the stability of a unique positive steady state and formulate conditions which guarantee the occurrence of the Hopf bifurcation. We show that oscillatory behaviour can be caused not only by time lag in protein transcription process, but also can be present in the model without time delay. Moreover, we investigate...
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Nitrogen-incorporated boron-doped diamond films for enhanced electrochemical supercapacitor performance
PublikacjaThe electrochemical (EC) supercapacitor, known for its rapid charging, reliability, and versatile applications, demands optimized electrode characteristics and an understanding of their electrochemical behaviour. Although boron-doped diamond (BDD) holds promise as a supercapacitor electrode, a crucial gap exists in comprehending its material behaviour under specific growth conditions. Here, nitrogen-incorporated BDD (N-BDD) films...
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Effects of Road Infrastructure on Pedestrian Safety
PublikacjaThe objective of the work was to identify risks for pedestrians that involve road infrastructure and roadside and to define how selected elements of geometry and traffic layout affect driver behaviour (speed on approaching pedestrian crossings). The results have helped to formulate recommendations on pedestrian crossing design. The research included an analysis of 2013-2017 statistics to identify the...
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Does the Use of Cell Phones and Headphones at the Signalised Pedestrian Crossings Increase the Risk of Accident?
PublikacjaReduction of the number of fatalities among pedestrians remains a topical issue in Poland. For many years, this percentage has remained at around 30% of all those who were killed on the road. At the same time, there is an increase in the use of electronic devices by pedestrians and cyclists that may affect their perception when crossing the road. This can lead to traffic accidents. In order to investigate the problem, field studies...
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Surface diffusion and cluster formation of gold on the silicon (111)
PublikacjaPurpose: Investigation of the gold atoms behaviour on the surface of silicon by molecular dynamics simulation method. The studies were performed for the case of one, two and four atoms, as well as incomplete and complete filling of gold atoms on the silicon surface. Design/methodology/approach: Investigations were performed by the method of molecular dynamics simulation using the Large-scale Atomic/Molecular Massively Parallel...
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Comparative Study of the Mechanical Behaviour of Bitumen- and Cement-Dominated Mixtures with Reclaimed Asphalt
PublikacjaThe bitumen emulsion-based recycling is a commonly used maintenance treatment in the rehabilitation of low-and medium-volume roads in Europe. Nevertheless, the wide range of climatic conditions across the continent resulted in the variety of mixture concepts and the requirements being adopted for various local conditions. In this regard, the most commonly used parameter to distinguish between the main mixture concepts is bitumen...
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Behaviour of deformed steel columns exposed to impact load during earthquakes: numerical analysis
PublikacjaIt has been observed during earthquakes that the so called soft-storey failure of an upper floor of a building leads to considerable vertical impact load acting on structural members of the lower storeys. The aim of this paper is to investigate numerically the behaviour of horizontally deformed columns (deformation as the result of earthquake loading) that are additionally subjected to vertical impact load. In the first stage of...
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Alternative Modeling of Volunteer Based Systems
PublikacjaThe canonical approach to model a flow of a voluntary based computing, as presented in Chapter 7 may tax the capacity of the simulator, especially when a more complex model of Voluntary Computing, proposed in [1], is used which would imply that, for typical heterogeneous groups of volunteers, several thousands of threads would have to be run inside the simulator, to mimic closely the behaviour of every volunteer. This chapter presents...
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Analysis of Interspike-Intervals for the General Class of Integrate-and-Fire Models with Periodic Drive
PublikacjaWe study one-dimensional integrate-and-fire models of the general type x˙=F (t, x) and analyze properties of the firing map which iterations recover consecutive spike timings. We impose very week constraints for the regularity of the function F (t, x), e.g. often it suffices to assume that F is continuous. If additionally F is periodic in t, using mathematical study of the displacement sequence of an orientation preserving circle...
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Critical Case Stochastic Phylogenetic Tree Model via the Laplace Transform
PublikacjaBirth–and–death models are now a common mathematical tool to describe branching patterns observed in real–world phylogenetic trees. Liggett and Schinazi (2009) is one such example. The authors propose a simple birth–and–death model that is compatible with phylogenetic trees of both influenza and HIV, depending on the birth rate parameter. An interesting special case of this model is the critical case where the birth rate equals the...
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Evolutionary Ship Track Planning within Traffic Separation Schemes – Evaluation of Individuals
PublikacjaThe paper presents an extended version of the author’s Evolutionary Sets of Safe Ship Trajectories method. The method plans safe tracks of all ships involved in an encounter including speed reduction manoeuvres, if necessary, and taking into account Rule 10 of COLREGS, which specifies ships’ behaviour within Traffic Separation Schemes governed by IMO. The paper focuses on the evaluation phase of the evolutionary process and shows...
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A comprehensive approach to double inverted pendulum modelling
PublikacjaThe problem of mathematical modelling and indication of properties of a DIP has been investigated in this paper. The aim of this work is to aggregate the knowledge on a DIP modelling using the Euler-Lagrange formalism in the presence of external forces and friction. To indicate the main properties important for simulation, model parameters identification and control system synthesis, analytical and numerical tools have been used....
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Tailoring the electrochemical degradation of iron protected with polypyrrole films for biodegradable cardiovascular stents
PublikacjaThe degradation of polypyrrole (PPy) coated iron is studied in phosphate buffer saline solution at 37 °C by odd random phase multisine electrochemical impedance spectroscopy (ORP-EIS). PPy is electropolymerized with anti-inflammatory salicylates incorporated in the film, as a drug release system. The modelling of EIS over time provides the quantitative description of the corrosion behaviour of the material. Thus, the reliable...
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Comparison of Selection Schemes in Evolutionary Method of Path Planning
PublikacjaThis article compares an impact of using various selection schemes on the quality of the solution for the problem of planning the path for a moving object using the evolutionary method. In study case problem of avoiding collisions at sea is analyzed. The modelled environment includes static constraints (lands, canals, etc.) and dynamic objects (moving ships). Article analyses behaviour of selection schemes in two similar environments...
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Reliability And Safety As An Objective Of Intelligent Transport Systems In Urban Areas
PublikacjaTechnologies that use transport telematics offer tools for strengthening urban transport systems. They rationalise the use of the existing infrastructure and transport management systems, increase their reliability and safety and improve the transport behaviour of residents, while reducing the operating costs of transport. The main reason for using Intelligent Transport Systems (ITS) is the need to implement measures to reduce...
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Tripping limitations of residual current devices in photovoltaic installations
PublikacjaIn electrical installations with photovoltaic sources of energy, earth fault current may comprise alternating current component and direct current component. The waveform shape of this earth fault current mainly depends on the point of the fault and the properties of a photovoltaic power electronics converter. The waveform shape of the current influences operation of protection devices, especially tripping threshold of residual...
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On the material symmetry group for micromorphic media with applications to granular materials
PublikacjaWithin the framework of the theory of nonlinear elastic micromorphic continua we introduce the new definition of the local material symmetry group. The group consists of ordered triples of second- and third-order tensors describing such changes of a reference placement that cannot be recognized with any experiment. Using the definition we characterize the micromorphic isotropic media, micromorphic fluids, solids and special intermediate...
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Buckling analyses of cylindrical metal silos containing bulk solids
PublikacjaThe paper presents quasi-static 3D buckling analysis results of thin-walled cylindrical metal silos with and without bulk solids. The behaviour of the bulk solid was described with a hypoplastic constitutive model. Non-linear analyses with geometric and material non-linearity were performed with a perfect and an imperfect silo shell. Different initial geometric imperfections were considered. The influence of internally stored bulk...
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Numerical investigations on early indicators of fracture in concrete at meso-scale.
PublikacjaFracture is a major reason of the global failure of concretes. The understanding of fracture is important to ensure the safety of structures and to optimize the material behaviour. In particular an early prediction possibility of fracture in concretes is of major importance. In this paper, concrete fracture under bending was numerically analysed using the Discrete Element Method (DEM). The real mesoscopic structure of a concrete...
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Ocena zastosowania wybranych reguł wymiany narzędzi w systemie produkcyjnym
PublikacjaIn this paper, an integrated analytical and simulation modelling framework has been developed with the objective to explore total system planning and operational issues. It enables in particular structuring the alternative process flow in manufacturing systems and their extended investigation under different tool exchange rules with limited number of tool inventory. Simulation studies performed with the proposed rules in the environment...
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The power of silence? opinion contagion and the surprise of the polish 2005 parlamentary and presidential elections
PublikacjaThis paper investigates opinion contagion in collective behaviour using threshold model (Granovetter (1978), Krassa(1988)). The theoretical background is the spiral of silence concept developed by Noelle-Neumann (1974), arguing that people only assert their opinions if they perceive a minimal support from a relevant proportion of others. We apply the model to explain the dispersion between pre-elections preferences and the final...
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MODAL ANALYSIS OF REAL TIMBER FRAME HOUSES WITH DIFFERENT INSULATION MATERIALS
PublikacjaThe aim of this article is to present the results of a numerical modal analysis of two actual structures of timber frame buildings and the different behaviour due to the used insulation material. One model of the timber structure was filled with mineral wool, while the other with polyurethane foam. During the modal analysis, eigenvalues for both models have been determined. The results of the analysis clearly show the increase...
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Modelowanie kratownicy z kształtowników giętych na zimno z mimośrodami dodatnimi w węźle = Modelling of truss with cold-formed section and positive eccentricyty in the node.
PublikacjaThe topic of this research is establishing load-carrying capacity of compressed and tensed chords of trusses made of cold-formed open cross-sections. Occurrence of bending in the truss’ chord is the result of specific production technology assumed by the designer and producer of lattice girder’s systems. The aim of this research is to present methodology of conduct while creating numerical models that best depict the behaviour...
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Geometrically Nonlinear Analysis of Functionally Graded Shells Based on 2-D Cosserat Constitutive Model
PublikacjaIn this paper geometrically nonlinear analysis of functionally graded shells in 6-parameter shell theory is presented. It is assumed that the shell consists of two constituents: ceramic and metal. The mechanical properties are graded through the thickness and are described by power law distribution. Formulation based on 2-D Cosserat constitutive model is used to derive constitutive relation for functionally graded shells. Numerical...