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Wyniki wyszukiwania dla: THERMAL 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...
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Modeling of truss with cold-formed section and positive eccentricity in the node
PublikacjaThis work is dedicated to establishing the load carrying capacity of tensed and compressed truss’ nodes made of cold-formed open cross sections. The occurrence of bending in the truss’ nodes is the result of a specific production technology for system lattice girders assumed by the designer and the producer. The aim of this research is to present the methodology of conduct for creation of computational models that best depict the...
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Relevance of Urban Freight Transport Modelling Towards the Challenges of Urban Freight Policy
PublikacjaThe main objective of this paper is to investigate how recent trends in urban freight transport analysis and modelling are related to urban freight measures set out in Gdynia’s 2016 Sustainable Urban Mobility Plan. Building on the literature a review framework was defined including 1) stakeholders, 2) descriptors, 3) objectives and 4) solution approach applied in freight modelling efforts. It was clear that the implementation...
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Modelling of performance of an AUV stealth vehicle. Design for operation.
PublikacjaIn the paper some results of research connected with modelling of performance and risk assessment of an AUV stealth vehicle are presented. A general approach to design of the stealth AUV autonomous underwater vehicle under consideration is introduced. The basic stealth characteristics of the AUV stealth vehicle are briefly described. The method of research is introduced. The AUV stealth vehicle concept is presented including the...
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Modeling of performance of an AUV stealth vehicle. Design for operation.
PublikacjaIn the paper some results of research connected with modelling of performance and risk assessment of an AUV stealth vehicle are presented. A general approach to design of the stealth AUV autonomous underwater vehicle under consideration is introduced. The basic stealth characteristics of the AUV stealth vehicle are briefly described. The method of research is introduced. The AUV stealth vehicle concept is presented including the...
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Shaft friction from the DMT and direct shear interface tests
PublikacjaThe article presents preliminary attempt to create tri-linear transfer curves for describing pile behaviour under axial loading. Transfer curves would use the parameter measured in dilatometer test, particularly a constrained modulus MDMT. The proposed method is based on concrete rough and smooth interface tests performed in a direct shear apparatus. Based on the obtained mobilization curves, relationships were created between...
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The effect of fishing basin construction on the behaviour of a footbrdge over the port channel
PublikacjaThe paper analyses possible causes of failure of the rotating footbridge over the Ustka port channel. In July, 2015, strange behaviour of this object was observed in the form of excessive vibrations of bridge platform suspension rods, with the accompanying acoustic effects. A preliminary geotechnical analysis has revealed that this destructive effect was caused by the nearby construction works, namely construction of a fishing...
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Evaluation of the stiffness modulus and phase angle of cold in-place recycled mix-tures for long curing periods
PublikacjaArticle presents the changes inbehaviour of cold-in place recycling mixtures made using cement and bituminous emulsion (CIR mixtures) after anelongated time of curing. Most of the available literatureregarding change instiffness modulus and phase angle presents resultsfor a maximum of several dozen days,which makesit difficult to predict the behaviour over the whole life of the compacted layer. The article...
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EVALUATING THE EFFECTIVENESS OF NON-PHYSICAL SPEED MANAGEMENT MEASURES
PublikacjaThe subject of the Authors' analyses is a group of non-physical speed management measures. How effective they are depends primarily on how willing drivers are to accept restrictions. Social and cultural factors play a major role. The effectiveness of these measures is not clear and requires further research. The authors conducted such research and evaluated the effects of nonphysical speed management measures on driver behaviour...
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Refinement of the Hardening Soil model within the small strain range
PublikacjaThe popularity of the elasto-plastic Hardening Soil (HS) model is based on simple parameter identification from standard testing and empirical formulas. The HS model is implemented in many commercial FE codes designed to analyse geotechnical problems. In its basic version, the stress–strain behaviour within the elastic range is subject to the hypoelastic power law, which assures the barotropy of the elastic stiffness. However,...
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Acoustic Hysteresis in Flows with Different Kinds of Relaxation and Attenuation
PublikacjaGraphs in the thermodynamic plane acoustic pressure versus excess acoustic density representing acoustic hysteresis, are considered as indicators of relaxation processes, equilibrium parameters of a flow, and kinds of wave exciters. Some flows with deviation from adiabaticity are examined: the Newtonian flow of a thermocon- ducting gas, the flow of a gas with vibrational relaxation, the flow of liquid electrolyte with a chemical...
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Towards the participant observation of emotions in software development teams
PublikacjaEmotions, moods and temperament influence our behaviour in every aspect of life. Until now plenty of research has been conducted and many theories have been proposed to explain the role of emotions within the working environment. However, in the field of software engineering, interest in the role of human factors in the process of software development is relatively new. In the paper the research design process that has been proposed...
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Experimental study on ultrasonic monitoring of splitting failure in reinforced concrete
PublikacjaThis paper investigates inspection of reinforced concrete elements sensitive to the splitting failure. The behaviour of a reinforced concrete specimen subjected to a tensile stress is considered. The damage detection procedure is based on the ultrasonic wave propagation technique. The piezoelectric transducers are located on both ends of the specimen and the measurements are taken periodically during the incrementally increased...
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Cyanides in the environment—analysis—problems and challenges
PublikacjaCyanide toxicity and their environmental impact are well known. Nevertheless, they are still used in the mining, galvanic and chemical industries. As a result of industrial activities, cyanides are released in various forms to all elements of the environment. In a natural environment, cyanide exists as cyanogenic glycosides in plants seeds. Too much consumption can cause unpleasant side effects. However, environmental tobacco smoke...
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The response of three colliding models of steel towers to seismic excitation
PublikacjaA number of past and recent observations have confirmed that collisions between adjacent, insufficiently-separated structures occurring as a result of seismic excitation (structural pounding) may result in serious damage to structural elements and can even lead to their total destruction. This paper summarises the results obtained from a shaking table experimental study which investigated structural pounding between three adjacent...
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Periodic Properties of 1D FE Discrete Models in High Frequency Dynamics
PublikacjaFinite element discrete models of various engineering 1D structures may be considered as structures of certain periodic characteristics. The source of this periodicity comes from the discontinuity of stress/strain field between the elements. This behaviour remains unnoticeable, when low frequency dynamics of these structures is investigated. At high frequency regimes, however, its influence may be strong enough to dominate calculated...
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Safety of erection and repair of steel tanks with geometric imperfections using heavylift jack-up system
PublikacjaSafety analysis is performed of cylindrical vertical steel tanks during erection using heavylift jack up system. During an assembly or repair process a set of hydraulic supports is used. It allows to use the in-place lifting of heavy steel constructions on the required height. Wind can strongly influence stability of the lifted tank. Any geometric imperfections can reduce the critical or limit load. In the work failures of the...
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Modal analysis of cylindrical steel tanks
PublikacjaCylindrical steel tanks are very popular structures used for storage of products of chemical and petroleum industries. Their safety and reliability is crucial because any failure could have serious consequences. The aim of present paper is to show the results of the first phase of investigation of seismic behaviour such structures. Modal analysis using Finite Element Method (FEM) for three models of real tanks used in Poland has...
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Experimentation, material modelling and simulation of bonded joints with a flexible adhesive
PublikacjaThe paper deals with material parameters identification of a flexible adhesive and the numerical simulation of its behaviour in a single lap bonded joint. The material modelling was based on the simple shear and tensile-shear laboratory tests of the bonded joints made of thin aluminium and polyurethane plates with the flexible adhesive Terostat MS 9360 manufactured by Henkel AG & Co. The adhesive was considered as a hyperelastic...
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The effect of current delay angle on tripping of residual current devices
PublikacjaPower electronics converters applied in domestic or similar installations may utilize current delay (phase) angle control to change the level of transferred power. Due to application of such types of converters, earth fault current in the installation may be strongly distorted. The current distortion level depends on a value of current delay angle. This delay angle also influences the tripping threshold of residual current devices....
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On phase equilibrium of an elastic liquid shell with wedge disclination
PublikacjaBased on the six-parameter shell theory we consider the phase equilibrium of a two-phase liquid membrane containing a wedge disclination. The considered problems are related to modelling of phase transitions in biological or lipid membranes. In order to capture the membrane behaviour we consider a special case of elastic shells which energy is invariant under major transformations of a reference configuration and can be treated...
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Simplified Method of Modelling Behaviour of Ship in Waves with Partially Flooded Compartments
PublikacjaThis paper contains a description of a numerical model for calculating behaviour of ships in waves. There are many models available, but the one described here can be characterised with a set of parameters that have a decisive impact on the final values of roll motion amplitude and frequency. In this paper, it is shown how a fitting of a standard-shape hull characterised by certain readily available parameters affects...
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Automatic Analysis of Trajectories of Moving Objects
PublikacjaOngoing monitoring is essential to providing security and safety of maritime and air operations. This paper presents the research in the area of automatic analysis of movement of unrestricted vehicles like ships and air-planes. The analysis is aimed at extraction of trajectory information, and the results can be used to identify anomalous behaviour in archived and real-time data. In this paper we focus on data acquired using the...
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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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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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Mixed, quantum-classical description of electron density transfer in the collision process
PublikacjaIn this work, we investigate an ion-atom model describing the time-dependent evolution of electron density during the collision. For a S3+- H system, numerical simulations are based on classical trajectory calculations, and the electron density behaviour is described with the time-dependent Schrödinger equation. We apply the finite difference method to obtain quantitative insights into the charge transfer dynamics, providing detailed...
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The role of governance to support smart community development: a systematic literature review
PublikacjaThis paper studies the interaction between the smart community and smart governance concepts to elaborate on the role of governance to support local governments in developing smart communities’ strategies and solutions. We perform a systematic literature review to analyse how the concept of smart community has advanced in terms of its definitions, context, benefits, challenges, and enablers and propose a unified term with a focus...
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Failure characterisation of sandwich beams using integrated acoustic emission and digital image correlation techniques
PublikacjaThe paper presents the experimental study of the failure behaviour of sandwich beams subjected to bending. The samples examined are sandwich beams made of polyethylene terephthalate foam core and glass fibre-reinforced polymer laminate face sheets. In a series of experiments, it has been proposed to integrate diagnostic techniques with acoustic emission and digital image correlation to accurately track the cracking process on the...
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Modelling the malware propagation in mobile computer devices
PublikacjaNowadays malware is a major threat to the security of cyber activities. The rapid develop- ment of the Internet and the progressive implementation of the Internet of Things (IoT) increase the security needs of networks. This research presents a theoretical model of malware propagation for mobile computer devices. It is based on the susceptible-exposed- infected-recovered-susceptible (SEIRS) epidemic model. The scheme is based on...
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Distortional buckling of composite thin-walled columns of a box-type cross section with diaphragms
PublikacjaDistortional buckling of axially compressed columns of box-like composite cross sections with andwithout internal diaphragms is investigated in the framework of one-dimensional theory. The channel membersare composed of unidirectional fibre-reinforced laminate. Two approaches to the member orthotropic materialare applied: homogenization based on the theory of mixture and periodicity cells, and homogenization basedon the Voigt–Reuss...
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Comparative molecular dynamics study of dimeric and monomeric forms of HIV-1 protease in ligand bound and unbound state
PublikacjaHuman immunodeficiency virus type 1 protease (HIV-1 PR) is a viral-encoded enzyme that forms a homodimer. HIV-1 PR is essential for replication and assembly of the virus and inactivation of HIV-1 PR enzyme causes production of immature, noninfectious viral particles and thus HIV-1 PR is an attractive target in anti-AIDS drug design. In our current work, we performed molecular dynamics (MD) calculations (500 ns) for two different...
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Pedestrian Safety at Midblock Crossings on Dual Carriageway Roads in Polish Cities
PublikacjaRoad crossings across two or more lanes in one direction are particularly dangerous due to limited sight distance and high vehicle speeds. To improve their safety, road authorities should provide safety treatments. These may include additional measures to reduce speed and narrow the road cross-section and the introduction of active pedestrian crossings. Equipped with flashing lights activated automatically when a pedestrian is...
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Investigation of behaviour of metal structures with polymer dampers under dynamic loads
PublikacjaA large number of accidents concerning structures subjected to dynamic loads have been recently observed. One of the examples of such a structure is a temporary steel grandstand erected using scaffolding system. Dynamic load that is generated by crowd movement has a significant influence on the behaviour of the structure and may lead to excessive structural vibrations. The aim of the study is to consider the idea of using polymer...
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Experimental and computational study on mechanical behaviour of carpentry corner log joints
PublikacjaThis work concerns experimental and numerical research on carpentry joints used in historic wooden buildings in southeastern Poland and western Ukraine. These structures are mainly sacred buildings, and the types of corner log joints characteristic of this region are primarily saddle-notch and dovetail joints; thus, these two types of joints were analysed in this study. The modelling of historic timber structures is a complex...
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pH -Tunable equilibria in azocrown ethers with histidine moieties, Bioelectrochemistry
PublikacjaThe crown ethers with electro- and photoactive azo moieties containing substituents with mobile protons such as in the –COOH groups of histidine, show unique effect of pH switched on/off presence of the azo form. The differences observed for the electrochemical behavior of azocrown ethers with N-acetylhistidine and imidazole moieties reveal the interference of a chemical reduction pathway in strongly acidified solutions. This...
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Deep compaction control of sandy soils
PublikacjaVibroflotation, vibratory compaction, micro-blasting or heavy tamping are typical improvement methods for the cohesionless deposits of high thickness. The complex mechanism of deep soil compaction is related to void ratio decrease with grain rearrangements, lateral stress increase, prestressing effect of certain number of load cycles, water pressure dissipation, aging and other effects. Calibration chamber based interpretation...
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Speed management on local government managed roads – research, recommendations and guidelines
PublikacjaCommissioned by the National Road Safety Council Secretariat, the project “Guidelines for speed management on local government managed roads” studied car driver be haviour when subjected to selected speed management measures such a local speed restrictions, surveillance, traffic calming and restricted speed areas. In addition, analyses were conducted on the impact of selected me asures...
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Scenarios in regional planning – theory and practice in Poland
PublikacjaAbstract. It is important to recognise future conditions in planning because it primes future actions. Scenarios are useful prognostic tools, especially when the social and institutional behaviour plays a crucial role. The aims of the paper are: (1) to indicate the roles and the place of scenarios in the strategic plan building process; (2) to analyse and evaluate the application of scenarios in regional planning in Poland; (3)...
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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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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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Anti-plane surface waves in media with surface structure: Discrete vs. continuum model
PublikacjaWe present a comparison of the dispersion relations derived for anti-plane surface waves using the two distinct approaches of the surface elasticity vis-a-vis the lattice dynamics. We consider an elastic half-space with surface stresses described within the Gurtin–Murdoch model, and present a formulation of its discrete counterpart that is a square lattice half-plane with surface row of particles having mass and elastic bonds different...
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Numerical analysis and in situ tests of the Grot Rowecki Bridge in Warsaw
PublikacjaThe paper presents the FEM analysis of the reconstructed the Grot-Rowecki Bridge over Vistula river in Warsaw. The bridge has seven spans and consists of two independent structures with the longest spans of 120 m. After reconstruction the bridge is over 10 m wider. The numerical, nonlinear analysis has been con-ducted on a global and local FEM models. These models are defined so as they strictly comply with global structural bridge...
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Technical fabrics in costruction of large scale roofs - numerical and experimental aspects
PublikacjaDesigning and construction of textile hanging roofs is the challenging subject for engineers. This type of structure needs geometrically and very often also physically non-linear calculations. Due to different behaviour of two families of threads (warp and weft), which during deformation can change the angle between their directions, they require special constitutive modelling. Also the loading of hanging roofs is very special....
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EXPERIMENTAL STUDY OF SURFACE ROUGHNESS EFFECT ONTHE RHEOLOGICAL BEHAVIOR OF MR FLUID
PublikacjaPaper presents the results of shear stress measurements of a commercial magnetorheological fluid using a plate-plate type geometry with a modified working surface. The purpose of the study was to determine the effect of changing the roughness of the measuring plate on the obtained shear stress results. Controlled shear rate tests and Magneto Sweep measurements were carried out for three MR fluid layer heights. The tests were...
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On modelling and non-linear elasto-plastic analysis of thin shells with deformable junctions
PublikacjaThe undeformed base surface of the irregular thin shell is modelled by the union of a finite number of regular smooth surface elements joined together along spatial curvilinear surface edges. The equilibrium conditions are formulated by postulating an appropriate form of the principle of virtual work, where also deformability of shell junctions is taken into account. The PVW is then discretised by C1 finite elements and the incremental-iterative...
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Kernel PCA in Application to Leakage Detection in Drinking Water Distribution System
PublikacjaMonitoring plays an important role in advanced control of complex dynamic systems. Precise information about system's behaviour, including faults detection, enables efficient control. Proposed method- Kernel Principal Component Analysis (KPCA), a representative of machine learning, skilfully takes full advantage of the well known PCA method and extends its application to nonlinear case. The paper explains the general idea of KPCA...
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Preliminary experimental research on stability of truss' joint with positive eccentricity
PublikacjaRecently, a very large interest in lightweight steel structures made from cold-formed sections has been noticeable. In the design practice, a large emphasis is put on rational shaping of both the thin-walled elements and constructions designed on them. The aim of this paper is to present the methodology for preparation of experimental research that model the behaviour of members in trusses made of cold-formed sections with positive...
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Experimental and numerical study on polymer element used for reduction of temporary steel grandstand vibrations
PublikacjaThe purpose of the paper is to analyse the effectiveness of a polymer damper in reduction of a temporary steel grandstand vibrations through the experimental and numerical study. The damper considered in the investigation is constructed out of two L-shape steel members bonded with polymer mass of high damping properties. The element has been installed as a diagonal one at the back part of the structure. The method has been compared...
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Distribution of the displacement sequence of an orientation preserving circle homeomorphism
PublikacjaIn some applications not only the knowledge of the behaviour of trajectories of a map is important, but also their displacements. We describe in detail the distribution of elements of the displacement sequence along a trajectory of an orientation preserving circle homeomorphism ϕ with irrational rotation number ϱ(ϕ). The values of displacement are dense in a set which depends on the map γ (semi-)conjugating ϕ with the rotation...
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On the interspike-intervals of periodically-driven integrate-and-fire models
PublikacjaWe analyze properties of the firing map, which iterations give information about consecutive spikes, for periodically driven linear integrate-and-fire models. By considering locally integrable (thus in general not continuous) input functions, we generalize some results of other authors. In particular, we prove theorems concerning continuous dependence of the firing map on the input in suitable function spaces. Using mathematical...