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Search results for: finite element method (fem)
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On the convergence of a nonlinear finite-difference discretization of the generalized Burgers–Fisher equation
PublicationIn this note, we establish analytically the convergence of a nonlinear finite-difference discretization of the generalized Burgers-Fisher equation. The existence and uniqueness of positive, bounded and monotone solutions for this scheme was recently established in [J. Diff. Eq. Appl. 19, 1907{1920 (2014)]. In the present work, we prove additionally that the method is convergent of order one in time, and of order two in space. Some...
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Hybrid Multi-Criteria Method of Analyzing the Location of Distributed Renewable Energy Sources
PublicationThis paper presents the development and the application of a hybrid multi-criteria method, the combination of the Analytic Hierarchy Process (AHP), and numerical taxonomy (NT),to support the decision making on the location of distributed renewable energy sources meetingvarious types of assessment criteria. Finding criteria weights, using the AHP method, eliminates thedisadvantage of NT—which, in current form, is defined by its...
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Ultrasound monitoring for evaluation of damage in reinforced concrete
PublicationThe paper deals with automated monitoring of damage evolution in concrete elements subjected to three-point bending tests. The monitoring is based on the nonlinear interactions of traveling ultrasonic waves with micro-crack zones inside the concrete specimens and surface-breaking cracks. The developed procedure assumes semi-continuous ultrasonic testing during the element full loading cycle and generation of the power spectral...
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Surface sliding in human abdominal wall numerical models: Comparison of single-surface and multi-surface composites
PublicationDetermining 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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Smart Weighing Scale with Feet-Sampled ECG
PublicationIn a smart home, health and well-being monitoring systems could be embedded in everyday devices providing a pervasive care. A home bathroom scale is an example of such a device, typically used to measure body weight and very often its composition (e.g. body water/fat percentage). In this paper, we analyzed a potential use of the bathroom scale to measure electrocardiogram (ECG) from electrodes located on the scale's tile. In particular...
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A study on diagnosing both isotropic and orthotropic, intentionally damaged laminates
PublicationBeing the most detrimental mode in laminated structures, delamination initially degrades local structural strength, and lastly causes global structural failure, thus necessitating delamination identification at its incipient stages. For identification purposes, a comprehensive numerical and experimental study on delamination within both the laminated isotropic acrylic-glass and orthotropic epoxyglass plates is presented. As the...
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A Numerical Study on Baseline-Free Damage Detection Using Frequency Steerable Acoustic Transducers
PublicationIn structural health monitoring (SHM) a considerable amount of damage detection algorithms based on guided waves (GW) have been developed. Most of them rely on extensive transducer networks, besides preliminary reference measurements of the structures. This originated a growing demand for hardware simplification and cost reduction of the wave-based SHM methods, driving the conception of new solutions enabling both: the reduction...
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Behaviour of orthotropic surgical implant in hernia repair due to the material orientation and abdomen surface deformation
Publicationrelation to the different range of typical deformations observed in different directions and zones of abdomen surface due to the patients’ life activities, has a significant influence on the extreme junction forces in the mesh–tissue connections and hence the repair persistence. The finite element model of the orthotropic implant was developed, and the junction forces in the connections of tissue and mesh were studied. The kinematical...
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Balance errors generated by numerical diffusion in the solution of non-linear open channel flow equations
PublicationThe paper concerns the untypical aspect of application of the dissipative numerical methods to solve nonlinear hyperbolic partial differential equations used in open channel hydraulics. It is shown that in some cases the numerical diffusion generated by the applied method of solution produces not only inaccurate solution but as well as a balance error. This error may occur even for an equation written in the conservative form not...
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Determination of Thermophysical Parameters Involved in The Numerical Model to Predict the Temperature Field of Cast-In-Place Concrete Bridge Deck
PublicationThe paper dealswith a concept of a practical computationmethod to simulate the temperature distribution in an extradosed bridge deck. The main goal of the study is to develop a feasible model of hardening of concrete consistent with in-situ measurement capabilities. The presented investigations include laboratory tests of high performance concrete, measurements of temperature evolution in the bridge deck and above all, numerical...
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Vortex flow caused by periodic and aperiodic sound in a relaxing maxwell fluid
PublicationThis paper concerns the description of vortex flow generated by periodic and aperiodic sound in relaxing Maxwell fluid. The analysis is based on governing equation of vorticity mode, which is a result of decomposition of the hydrodynamic equations for fluid flow with relaxation and thermal conductivity into acoustical and non-acoustical parts. The equation governing vorticity mode uses only instantaneous, not averaged over sound...
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Guided wave propagation for assessment of adhesive bonding between steel and concrete
PublicationAdhesive bonding is becoming more increasingly important in joining of structural elements. In civil engineering, there is a growing interest in connection by adhesive bonding in steel-concrete flexural members. This study concerns the guided wave propagation technique applied to condition assessment of an adhesive connection between a steel member and a concrete beam. Various states of degradation were considered by producing...
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Diagnostics of pillars in St. Mary’s Church (Gdańsk, Poland) using the GPR method
PublicationThe main goal of this study was non-destructive evaluation of pillars in the St. Mary’s Church (Gdańsk, Poland) using the ground penetrating radar (GPR) technique. The GPR inspection was conducted on four brick masonry pillars and five pillars strengthened by reinforced concrete jacketing. Data were acquired with a 2 GHz antenna along longitudinal and transverse profiles. The study involved the estimation of the electromagnetic...
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Identification and non-integer order modelling of synchronous machines operating as generator
PublicationThis paper presents an original mathematical model of a synchronous generator using derivatives of fractional order. In contrast to classical models composed of a large number of R-L ladders, it comprises half-order impedances, which enable the accurate description of the electromagnetic induction phenomena in a wide frequency range, while minimizing the order and number of model parameters. The proposed model takes into account...
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Estimation of smokers' exposure to mercury from combustible tobacco products, based on the approach used in food consumers’ exposure estimation
PublicationSmoking has been known to mankind for centuries, but it is only in recent decades that much attention has been paid to the harmfulness of this habit. Mercury inhalation is particularly dangerous in this respect and smoking creates extremely favorable conditions for the emission and targeted delivery of this element into the lungs. Despite this fact, a lack of a clear method for estimating the exposure of tobacco consumers to mercury...
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Robust estimation of deformation from observation differences for free control networks
PublicationDeformation measurements have a repeatable nature. This means that deformation measurements are performed often with the same equipment, methods, geometric conditions and in a similar environment in epochs 1 and 2 (e.g., a fully automated, continuous control measurements). It is, therefore, reasonable to assume that the results of deformation measurements can be distorted by both random errors and by some non-random errors, which...
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Evaluation of Three Peptide Immobilization Techniques on a QCM Surface Related to Acetaldehyde Responses in the Gas Phase
PublicationThe quartz-crystal microbalance is a sensitive and universal tool for measuring concentrations of various gases in the air. Biochemical functionalization of the QCM electrode allows a label-free detection of specific molecular interactions with high sensitivity and specificity. In addition, it enables a real-time determination of its kinetic rates and affinity constants. This makes QCM a versatile bioanalytical screening tool for...
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THE METHOD OF MEASURING THE MEMBRANE COVER GEOMETRY USING LASER SCANNING AND SYNCHRONOUS PHOTOGRAMMETRY
PublicationThe authors present the experience and results of field studies carried out at the technical acceptance of Forest Opera (name in Polish: Opera Leśna) in Sopot (Poland). An unusual design of covering made in the form of “Sheerfill I” technical fabric membrane required spanned in the form of sails, required the use of terrestrial laser scanning. Such approach allowed for the fast and accurate record of the surface of individual panels...
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Biomechanics of the medial meniscus in the osteoarthritic knee joint
PublicationBackground. Increased mechanical loading and pathological response of joint tissue to the abnormal mechanical stress can cause degradation of cartilage characteristic of knee osteoarthritis (OA). Despite osteoarthritis is risk factor for the development of meniscal lesions the mechanism of degenerative meniscal lesions is still unclear. Therefore, the aim of the study is to investigate the influence of medial compartment knee OA...
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PROBLEMS OF THE STARTING AND OPERATING OF HYDRAULIC COMPONENTS AND SYSTEMS IN LOW AMBIENT TEMPERATURE (PART IV) MODELLING THE HEATING PROCESS AND DETERMINING THE SERVICEABILITY OF HYDRAULIC COMPONENTS DURING THE STARTING-UP IN LOW AMBIENT TEMPERATURE
PublicationDesigners of hydraulically driven machines and devices are obliged to ensure during design process their high service life with taking into account their operational conditions. Some of the machines may be started in low ambient temperature and even in thermal shock conditions (due to delivering hot working medium to cold components). In order to put such devices into operation appropriate investigations, including experimental...
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Numerical Issues and Approximated Models for the Diagnosis of Transmission Pipelines
PublicationThe chapter concerns numerical issues encountered when the pipeline flow process is modeled as a discrete-time state-space model. In particular, issues related to computational complexity and computability are discussed, i.e., simulation feasibility which is connected to the notions of singularity and stability of the model. These properties are critical if a diagnostic system is based on a discrete mathematical model of the flow...
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Reinforcement Learning Algorithm and FDTD-based Simulation Applied to Schroeder Diffuser Design Optimization
PublicationThe aim of this paper is to propose a novel approach to the algorithmic design of Schroeder acoustic diffusers employing a deep learning optimization algorithm and a fitness function based on a computer simulation of the propagation of acoustic waves. The deep learning method employed for the research is a deep policy gradient algorithm. It is used as a tool for carrying out a sequential optimization process the goal of which is...
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Modeling the debonding process of osseointegrated implants due to coupled adhesion and friction
PublicationCementless implants have become widely used for total hip replacement surgery. The long-term stability of these implants is achieved by bone growing around and into the rough surface of the implant, a process called osseointegration. However, debonding of the bone–implant interface can still occur due to aseptic implant loosening and insufficient osseointegration, which may have dramatic consequences. The aim of this work is to...
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Limits of enhanced of macro- and meso-scale continuum models for studying size effect in concrete under tension
PublicationThe paper investigates a mechanical quasi-static size effect in concrete during splitting tension at the macro- and meso-level. In experiments, five different diameters of cylindrical concrete specimens were tested. Twodimensional plane strain finite element (FE) simulations were carried out to reproduce the experimental size effect. The size effect in experiments by Carmona et al. was also simulated. Two enhanced continuum concrete...
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Method for universal detection of two-photon polarization entanglement
PublicationDetecting and quantifying quantum entanglement of a given unknown state poses problems that are fundamentally important for quantum information processing. Surprisingly, no direct (i.e., without quantum tomography) universal experimental implementation of a necessary and sufficient test of entanglement has been designed even for a general two-qubit state. Here we propose an experimental method for detecting a collective universal...
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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
PublicationThe 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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MODELLING OF CONCRETE FRACTURE AT AGGREGATE LEVEL USING DEM BASED ON X-RAY mu CT IMAGES OF INTERNAL STRUCTURE
PublicationThe 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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Algorytmy przetwarzania widm Ramana w procesie detekcji substancji chemicznych
PublicationRozprawa przedstawia szczegółowo algorytmy, jakie są stosowane podczas przetwarzania widm Ramana, rejestrowanych przenośnym spektrometrem o skończonej rozdzielczości. Pracę podzielono na osiem rozdziałów. W pierwszym określono cel i tezy pracy. Rozdział drugi opisuje podstawowe pojęcia dotyczące zjawiska Ramana oraz zasady budowy urządzeń do pomiarów widm Ramana. W rozdziale trzecim scharakteryzowano błędy występujące podczas pomiarów...
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A high-accuracy method of computation of x-ray waves propagation through an optical system consisting of many lenses
PublicationThe propagation of X-ray waves through an optical system consisting of many X-ray refractive lenses is considered. Two differential equations are contemplated for solving the problem for electromagnetic wave propagation: first – an equation for the electric field, second – an equation derived for a complex phase of an electric field. Both equations are solved by the use of a finite-difference method. The simulation error is estimated...
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A high-accuracy complex-phase method of simulating X-ray propagation through a multi-lens system
PublicationThe propagation of X-ray waves through an optical system consisting of many X-ray refractive lenses is considered. For solving the problem for an electromagnetic wave, a finite-difference method is applied. The error of simulation is analytically estimated and investigated. It was found that a very detailed difference grid is required for reliable and accurate calculations of the propagation of X-ray waves through a multi-lens...
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Zastosowanie sygnałów o projektowanych kształtach do diagnostyki obiektów wysoko-impedancyjnych metodą spektroskopii impedancyjnej
PublicationW artykule przedstawiono metodę szybkiej spektroskopii impedancyjnej obiektów o wysokich impedancjach (|Zx| > 1 GOhm) z zastosowaniem sygnałów o projektowanych kształtach. Sygnał pobudzenia wytwarzany jest w module DAQ U2531A i doprowadzany na wejście badanego obiektu za pośrednictwem przetwornika cyfrowo-analogowego (CA). Sygnały odpowiedzi proporcjonalne do napięcia na mierzonej impedancji Zx oraz prądu płynącego przez Zx są...
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The Effectiveness of Polymer Damper in Damage Reduction of Temporary Steel Grandstand
PublicationA large number of accidents involving damage of temporary grandstands during different types of events were observed in the past. The aim of the paper is to analyse numerically the effectiveness of a polymer damper in damage reduction of a temporary steel scaffolding grandstand exposed to dynamic load due to jumping. 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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Experimental and numerical study on polymer element used for reduction of temporary steel grandstand vibrations
PublicationThe 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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Calibration of precipitation estimation algorithm with particular emphasis on the Pomeranian region using high performance computing
PublicationFast and accurate precipitation estimation is an important element of remote atmosphere monitoring, as it allows, for example, to correct short-term weather forecasts and the prediction of several types of meteorological threats. The paper presents methodology for calibrating precipitation estimation algorithm based on MSG SEVIRI sensor data, and Optimal Cloud Analysis product available via EumetCast transmission. Calibration is...
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A Comparison of Simplified Two-dimensional Flow Models Exemplified by Water Flow in a Cavern
PublicationThe paper shows the results of a comparison of simplified models describing a two-dimensional water flow in the example of a water flow through a straight channel sector with a cavern. The following models were tested: the two-dimensional potential flow model, the Stokes model and the Navier-Stokes model. In order to solve the first two, the boundary element method was employed, whereas to solve the Navier-Stokes equations, the...
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The New 3D Printed Left Atrial Appendage Closure with a Novel Holdfast Device: A Pre-Clinical Feasibility Animal Study
PublicationMany patients undergoing cardiac surgery have risk factors for both atrial fibrillation and stroke. The left atrial appendage (LAA) is the primary site for thrombi formation. Therefore LAA occlusion devices should be tested for their ability to reduce future cerebral ischemic events in patients with high-risk of haemorrhage. The aim of this study was to evaluate the safety and feasibility of a novel left atrial appendage exclusion...
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Modelling and Simulation of a New Variable Stiffness Holder for Milling of Flexible Details
PublicationModern industry expectations in terms of milling operations often demand the milling of the flexible details by using slender ball-end tools. This is a difficult task because of possible vibration occurrence. Due to existence of certain conditions (small depths of cutting, regeneration phenomena), cutting process may become unstable and self-excited chatter vibration may appear. Frequency of the chatter vibration is close to dominant...
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The influence of a change in the meniscus cross-sectional shape on the medio-lateral translation of the knee joint and meniscal extrusion
PublicationObjective The purpose of this study was to evaluate the influence of a change in the meniscus cross sectional shape on its position and on the biomechanics of a knee joint. Methods One main finite element model of a left knee joint was created on the basis of MRI images. The model consisted of bones, articular cartilages, menisci and ligaments. Eight variants of this model with an increased or decreased meniscus height were then...
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Continuum contact model for friction between graphene sheets that accounts for surface anisotropy and curvature
PublicationUnderstanding the interaction mechanics between graphene layers and co-axial carbon nanotubes (CNTs) is essential for modeling graphene and CNT-based nanoelectromechanical systems. This work proposes a new continuum contact model to study interlayer interactions between curved graphene sheets. The continuum model is calibrated and validated using molecular dynamics (MD) simulations. These are carried out employing the reactive...
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Nonlinear material identification of heterogeneous isogeometric Kirchhoff–Love shells
PublicationThis work presents a Finite Element Model Updating inverse methodology for reconstructing heterogeneous materialdistributions based on an efficient isogeometric shell formulation. It uses nonlinear hyperelastic material models suitable fordescribing incompressible material behavior as well as initially curved shells. The material distribution is discretized by bilinearelements such that the nodal values...
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Electrical Tree Growth Behavior Under AC and DC High Voltage in Power Cables
PublicationThis work investigates the impact of an applied AC and DC high voltage on the electrical tree behavior in extruded cross-linked polyethylene (XLPE) insulation based on simulation and experimental validation. Extensive partial discharge (PD) testing methods are being implemented for high voltage cables under AC voltage for monitoring their condition. However, these PD testing methods cannot be utilized for power cables under DC...
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Probabilistic analysis of settlements under a pile foundation of a road bridge pylon
PublicationThe paper addresses the reliability change of a road bridge pile foundation due to the unpredictable increase of settlements in time. The analysis is based on the Rędziński Bridge in Wrocław, Poland, its design assumptions, and monitoring results. The bridge foundation rests on a multi-layered subsoil assumed random. The Finite Element model of the subgrade is generated in ZSoil® software. To simplify the probabilistic approach,...
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Mitigating the seismic pounding of multi-story buildings in series using linear and nonlinear fluid viscous dampers
PublicationSeismic-induced pounding between adjacent buildings may have serious consequences, ranging from minor damage up to total collapse. Therefore, researchers try to mitigate the pounding problem using different methods, such as coupling the adjacent buildings with stiff beams, connecting them by using viscoelastic links, and installing damping devices in each building individually. In the current paper, the effect of using linear and...
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Behaviour of asymmetric structures with base isolation made of Polymeric Bearings
PublicationEarthquake-induced ground motions are the most severe and unpredictable threats to the structures all around the world. Seismic excitations cause a lot of damage in a wide variety of ways, leaving thousands of casualties in their wake. During the last few years alone, the world has witnessed many major earthquakes, five of which have caused far-reaching consequences of a national scale for Haiti (January 2010), Chile (February...
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The method of analysis of damage reinforced concrete beams using terrestial laser scanning
PublicationThe authors present an analysis of the possibility to assess deformations and mechanisms of destructing bent reinforced concrete beams using the terrestrial laser scanning. As part of the experiments carried out at the Regional Laboratory of Construction of the Concrete Structures Division of the Civil and Environmental Engineering Faculty at Gdansk University of Technology, the reinforced concrete beams were subjected to destruction...
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On topology optimization of large deformation contact-aided shape morphing compliant mechanisms
PublicationA 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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Atypical application of the parametric method for track infrastructure inventory
PublicationFor many years, satellite systems have seen widespread use in a variety of technical applications, as well as in operations related to setting-out and the exploitation of track infrastructure. Their main applications include an inventory of the trackage course and detecting changes in its position. In both of these tasks, the most important element that determines the quality of an analyses is the high accuracy of the determinations...
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Topological-numerical analysis of a two-dimensional discrete neuron model
PublicationWe conduct computer-assisted analysis of a two-dimensional model of a neuron introduced by Chialvo in 1995 [Chaos, Solitons Fractals 5, 461–479]. We apply the method of rigorous analysis of global dynamics based on a set-oriented topological approach, introduced by Arai et al. in 2009 [SIAM J. Appl. Dyn. Syst. 8, 757–789] and improved and expanded afterward. Additionally, we introduce a new algorithm to analyze the return times...
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Deformation Analysis of a Composite Bridge during Proof Loading Using Point Cloud Processing
PublicationRemote sensing in structural diagnostics has recently been gaining attention. These techniques allow the creation of three-dimensional projections of the measured objects, and are relatively easy to use. One of the most popular branches of remote sensing is terrestrial laser scanning. Laser scanners are fast and efficient, gathering up to one million points per second. However, the weakness of terrestrial laser scanning is the...
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Au–Si plasmonic platforms: synthesis, structure and FDTD simulations
PublicationPlasmonic platforms based on Au nanostructures have been successfully synthesized by directional solidification of a eutectic from Au and the substrate. In order to determine homogeneous shape and space distribution, the influence of annealing conditions and the initial thickness of the Au film on the nanostructures was analyzed. For the surface morphology studies, SEM and AFM measurements were performed. The structure of platforms...