Search results for: nonlinear systems
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Modeling of wood frame structures with different insulation materials under damaging dynamic loading
PublicationWood frame buildings are very popular in regions that are exposed to different dynamic excitations, such as damaging earthquakes. Their seismic resistance is really important in order to prevent structural damages and human losses. This paper presents the results of advanced numerical investigation carried out using the FEM. Based on the models of wall panels, the numerical model of real structure of the wood frame building has...
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Nonlinear impedance of 50Bi2VO5.5-50SrB4O7 glass measured with impedance spectroscopy method at low temperature region
Open Research DataThe nonlinear electrcial properties of 50(Bi2VO5.5)-50SrB4O7 glass was measured by impedance spectroscopy method.
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Nonlinear impedance of Bi2VO5.5 ceramic prepared by traditional melt quenching technique was measured with impedance spectroscopy method at low temperature region
Open Research DataThe nonlinear electrical properties of Bi2VO5.5 ceramic prepared by traditional melt quenching technique was measured by impedance spectroscopy method.
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Nonlinear impedance of 50Bi2VO5.5-50SrB4O7 annealed glass at 593 K measured with impedance spectroscopy method at high temperature region
Open Research DataThe nonlinear electrcial properties of 50Bi2VO5.5-50SrB4O7 annealed glass was measured by impedance spectroscopy method.
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Nonlinear impedance of 35Bi2VO5.5-65SrB4O7 glass measured with impedance spectroscopy method at high temperature region
Open Research DataThe nonlinear electrcial properties of 35Bi2VO5.5-65SrB4O7 glass was measured by impedance spectroscopy method.
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Nonlinear impedance of as-quenched 40Bi2VO5.5-60SrB4O7 glass measured with impedance spectroscopy method at high temperature region
Open Research DataThe nonlinear electrical properties of as-quenched 40Bi2VO5.5-60SrB4O7 glass was measured by impedance spectroscopy method.
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Nonlinear impedance of 30Bi2VO5.5-70SrB4O7 glass measured with impedance spectroscopy method at high temperature region
Open Research DataThe nonlinear electrcial properties of 30Bi2VO5.5-70SrB4O7 glass was measured by impedance spectroscopy method.
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Nonlinear impedance of 50Bi2VO5.5-50SrB4O7 glass measured with impedance spectroscopy method at high temperature region
Open Research DataThe nonlinear electrcial properties of 50(Bi2VO5.5)-50SrB4O7 glass was measured by impedance spectroscopy method.
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Nonlinear impedance of 45Bi2VO5.5-55SrB4O7 glass measured with impedance spectroscopy method at high temperature region
Open Research DataThe nonlinear electrcial properties of 45Bi2VO5.5-55SrB4O7 glass was measured by impedance spectroscopy method.
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Determination of t8/5 cooling times for underwater local dry welding of steel
PublicationKnowledge of thermal history is the basic condition for studying the structure - properties of welded joints. The determinant of thermal history is the thermal cycle, whose in-situ measurements are still a big challenge. Water as the welding environment complicates this issue even more. The article presents a method to determine an equation for calculating t8/5 cooling times for underwater gas metal arc welding of unalloyed steels...
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Sensorless Control of Induction Motor Based on Super-Twisting Sliding Mode Observer With Speed Convergence Improvement
PublicationThe super twisting sliding-mode observer (ST-SMO) has been proposed to achieve an effective method for alleviating low-order harmonics of measured quantities, issues related to DC drift, and suppression of chattering due to low-frequency sampling. The conventional ST-SMO, on the other hand, suffers from control delay in the convergence trajectory due to the system disturbance, resulting in decreased anti-disturbance capability...
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Linear viscoelastic transversely isotropic model based on the spectral decomposition of elasticity tensors
PublicationThe linear viscoelasticity is still a useful model in the engineering for studying the behavior of materials loaded with different loading rates (frequencies). Certain types of materials reveal also an anisotropic behavior: fiber reinforced composites, asphalt concrete mixtures, or wood, to name a few. In general, researchers try to identify experimentally the dependence of engineering constants like: directional Young’s moduli...
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Redundantly Actuated 3RRR Parallel Planar Manipulator - Numerical Analyses of its Dynamics Sensitivity on Modifications of its Platform’s Inertia Parameters
PublicationIn the paper, numerical analyses, as well as dynamics of a complex mechanism, are presented. Two objectives are crucial for the paper: inverse dynamic model is needed (dedicated to be use in the model predictive controller); an identification method is searched (some trajectory parameters are controlled, when specific trajectory is tracked under an open-loop model-based control), as selected parameters must be identified for the...
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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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Mechanical behaviour of knit synthetic mesh used in hernia surgery
PublicationPurpose: There is a discussion in literature concerning mechanical properties and modelling of surgical meshes. An important feature of elastic modulus dependency on load history is taken into account in this paper, as implants are subjected to variable loading during human activity. The example of DynaMesh®-IPOM surgical implant is studied. Methods: The analysis is based on failure tension tests and cyclic loading and unloading...
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Behaviour of deformed steel columns exposed to impact load during earthquakes: numerical analysis
PublicationIt 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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Fast Multi-Objective Aerodynamic Optimization Using Sequential Domain Patching and Multifidelity Models
PublicationExploration of design tradeoffs for aerodynamic surfaces requires solving of multi-objective optimization (MOO) problems. The major bottleneck here is the time-consuming evaluations of the computational fluid dynamics (CFD) model used to capture the nonlinear physics involved in designing aerodynamic surfaces. This, in conjunction with a large number of simulations necessary to yield a set of designs representing the best possible...
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Surrogate modeling of impedance matching transformers by means of variable‐fidelity electromagnetic simulations and nested cokriging
PublicationAccurate performance evaluation of microwave components can be carried out using full‐wave electromagnetic (EM) simulation tools, routinely employed for circuit verification but also in the design process itself. Unfortunately, the computational cost of EM‐driven design may be high. This is especially pertinent to tasks entailing considerable number of simulations (eg, parametric optimization, statistical analysis). A possible...
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Expedited Variable-Resolution Surrogate Modeling of Miniaturized Microwave Passives in Confined Domains
PublicationDesign of miniaturized microwave components is largely based on computational models, primarily, full-wave electromagnetic (EM) simulations. EM analysis is capable of giving an accurate account for cross-coupling effects, substrate and radiation losses, or interactions with environmental components (e.g., connectors). Unfortunately, direct execution of EM-based design tasks such as parametric optimization or uncertainty quantification,...
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An Instantaneous Engine Speed Estimation Method Using Multiple Matching Synchrosqueezing Transform
PublicationInstantaneous rotational speed measurement of the engine is crucial in routine inspection and maintenance of an automobile engine. Since the contact measurement of rotational speed is not always available, the vibration measurement has been used for noncontact rotational speed estimation methods. Unfortunately, the accuracy of the noncontact estimation methods by analyzing engine vibration frequency is not satisfactory due to the...
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Reliable data-driven modeling of high-frequency structures by means of nested kriging with enhanced design of experiments
PublicationData-driven (or approximation) surrogate models have been gaining popularity in many areas of engineering and science, including high-frequency electronics. They are attractive as a way of alleviating the difficulties pertinent to high computational cost of evaluating full-wave electromagnetic (EM) simulation models of microwave, antenna, and integrated photonic components and devices. Carrying out design tasks that involve massive...
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Efficient and robust quadratures for isogeometric analysis: Reduced Gauss and Gauss–Greville rules
PublicationThis work proposes two efficient quadrature rules, reduced Gauss quadrature and Gauss–Greville quadrature, for isogeometric analysis. The rules are constructed to exactly integrate one-dimensional B-spline basis functions of degree p, and continuity class C^{p−k}, where k is the highest order of derivatives appearing in the Galerkin formulation of the problem under consideration. This is the same idea we utilized in Zou et al....
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Results after grinding C45 steel
Open Research DataThe database contains results from nanoindenter, scanning microscope and also X-ray diffractometer. To determine the residual stresses and the size of the crystallites in the ferrite grains in the grinded surface layer, the Williamson Hall analysis of the X-ray diffraction patterns was performed. XRD diffraction patterns were also used to perform a...
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Nonlinear impedance as a function of A.C. voltage for glass 40Bi2VO5.5-60SrB4O7 annealed at 473 K for 3h and next fully crystallized measured with impedance spectroscopy method at high temperature region
Open Research DataThe nonlinear electrcial properties as a function of A.C. voltage for annealed at 473 K for 3h and next fully crystallized 40Bi2VO5.5-60SrB4O7 glass was measured by impedance spectroscopy method.
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Nonlinear impedance as a function of A.C. voltage for fully crystallized 35Bi2VO5.5-65SrB4O7 glass measured with impedance spectroscopy method at high temperature region
Open Research DataThe nonlinear electrcial properties as a function of A.C. voltage for fully crystallized 35Bi2VO5.5-65SrB4O7 glass was measured by impedance spectroscopy method.
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Nonlinear impedance of 45Bi2VO5.5-55SrB4O7 fully crystallized glass measured with impedance spectroscopy method at high temperature region
Open Research DataThe nonlinear electrcial properties of 45Bi2VO5.5-55SrB4O7 fully crystallized glass was measured by impedance spectroscopy method.
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Nonlinear impedance as a function of A.C. voltage for annealed and next fully crystallized 50Bi2VO5.5-50SrB4O7 glass measured with impedance spectroscopy method at high temperature region
Open Research DataThe nonlinear electrcial properties as a function of A.C. voltage for annealed and next fully crystallized 50Bi2VO5.5-50SrB4O7 glass was measured by impedance spectroscopy method.
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Nonlinear impedance of as-quenched glass 40Bi2VO5.5-60SrB4O7 after full crystallization was measured with impedance spectroscopy method at high temperature region
Open Research DataThe nonlinear electrcial properties of as-quenched glass 40Bi2VO5.5-60SrB4O7 afetr full crystallization was measured by impedance spectroscopy method.
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Nonlinear impedance of 40Bi2VO5.5-60SrB4O7 annealed glass at 473 K for 3 h measured with impedance spectroscopy method at high temperature region
Open Research DataThe nonlinear electrical properties of 40Bi2VO5.5-60SrB4O7 glass annealed at 473 K for 3h was measured by impedance spectroscopy method.
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Nonlinear impedance as a function of A.C. voltage for glass 40Bi2VO5.5-60SrB4O7 annealed at 593 K and next fully crystallized measured with impedance spectroscopy method at high temperature region
Open Research DataThe nonlinear electrcial properties as a function of A.C. voltage for annealed at 593 K and next fully crystallized 40Bi2VO5.5-60SrB4O7 glass was measured by impedance spectroscopy method.
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Nonlinear impedance of glass 40Bi2VO5.5-60SrB4O7 annealed at 473 K for 3h and next fully crystallized was measured with impedance spectroscopy method at high temperature region
Open Research DataThe nonlinear electrcial properties of glass 40Bi2VO5.5-60SrB4O7 annealed at 593 K and next fully crystallized was measured by impedance spectroscopy method.
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Nonlinear impedance of 35Bi2VO5.5-65SrB4O7 fully crystallized glass measured with impedance spectroscopy method at high temperature region
Open Research DataThe nonlinear electrcial properties of 35Bi2VO5.5-65SrB4O7 fully crystallized glass was measured by impedance spectroscopy method.
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Nonlinear impedance of annealed and next fully crystallized 50Bi2VO5.5-50SrB4O7 glass measured with impedance spectroscopy method at high temperature region
Open Research DataThe nonlinear electrcial properties of annealed and next fully crystallized 50Bi2VO5.5-50SrB4O7 glass was measured by impedance spectroscopy method.
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Nonlinear impedance of Bi2VO5.5 ceramic prepared by traditional melt quenching technique was measured with impedance spectroscopy method at high temperature region
Open Research DataThe nonlinear electrical properties of Bi2VO5.5 ceramic prepared by traditional melt quenching technique was measured by impedance spectroscopy method.
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Nonlinear impedance of 50Bi2VO5.5-50SrB4O7 fully crystallized glass at 813 K measured with impedance spectroscopy method at high temperature region
Open Research DataThe nonlinear electrcial properties of 50Bi2VO5.5-50SrB4O7 fully crystallized glass was measured by impedance spectroscopy method.
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Nonlinear impedance of 40Bi2VO5.5-60SrB4O7 annealed glass at 593 K measured with impedance spectroscopy method at high temperature region
Open Research DataThe nonlinear electrical properties of 40Bi2VO5.5-60SrB4O7 glass annealed at 593 K was measured by impedance spectroscopy method.
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Nonlinear impedance of 50Bi2VO5.5-50SrB4O7 partially crystallized glass at 613 K measured with impedance spectroscopy method at high temperature region
Open Research DataThe nonlinear electrcial properties of 50Bi2VO5.5-50SrB4O7 partially crystallized glass was measured by impedance spectroscopy method.
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Nonlinear impedance as a function of A.C. voltage for fully crystallized 45Bi2VO5.5-55SrB4O7 glass measured with impedance spectroscopy method at high temperature region
Open Research DataThe nonlinear electrcial properties as a function of A.C. voltage for fully crystallized 45Bi2VO5.5-55SrB4O7 glass was measured by impedance spectroscopy method.
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Nonlinear impedance of 30Bi2VO5.5-70SrB4O7 fully crystallized glass measured with impedance spectroscopy method at high temperature region
Open Research DataThe nonlinear electrcial properties of 30Bi2VO5.5-70SrB4O7 fully crystallized glass was measured by impedance spectroscopy method.
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Nonlinear impedance of glass 40Bi2VO5.5-60SrB4O7 annealed at 593 K and next fully crystallized was measured with impedance spectroscopy method at high temperature region
Open Research DataThe nonlinear electrcial properties of glass 40Bi2VO5.5-60SrB4O7 annealed at 593 K and next fully crystallized was measured by impedance spectroscopy method.
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The Influence of Articular Cartilage Thickness Reduction on Meniscus Biomechanics
PublicationObjective Evaluation of the biomechanical interaction between meniscus and cartilage in medial compartment knee osteoarthritis. Methods The finite element method was used to simulate knee joint contact mechanics. Three knee models were created on the basis of knee geometry from the Open Knee project. We reduced the thickness of medial cartilages in the intact knee model by approximately 50% to obtain a medial knee osteoarthritis...
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Machine-Learning-Based Global Optimization of Microwave Passives with Variable-Fidelity EM Models and Response Features
PublicationMaximizing microwave passive component performance demands precise parameter tuning, particularly as modern circuits grow increasingly intricate. Yet, achieving this often requires a comprehensive approach due to their complex geometries and miniaturized structures. However, the computational burden of optimizing these components via full-wave electromagnetic (EM) simulations is substantial. EM analysis remains crucial for circuit...
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Development and validation of lumbar spine finite element model
PublicationThe functional biomechanics of the lumbar spine have been better understood by finite element method (FEM) simulations. However, there are still areas where the behavior of soft tissues can be better modeled or described in a different way. The purpose of this research is to develop and validate a lumbar spine section intended for biomechanical research. A FE model of the 50th percentile adult male (AM) Total Human Model for Safety...
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Multi-region fuzzy logic controller with local PID controllers for U-tube steam generator in nuclear power plant
PublicationIn the paper, analysis of multi-region fuzzy logic controller with local PID controllers for steam generator of pressurized water reactor (PWR) working in wide range of thermal power changes is presented. The U-tube steam generator has a nonlinear dynamics depending on thermal power transferred from coolant of the primary loop of the PWR plant. Control of water level in the steam generator conducted by a traditional PID controller...
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Implementation of Solute Transport in the Vadose Zone into the “HYDRUS Package for MODFLOW”
PublicationThe “HYDRUS package for MODFLOW” is an existing MODFLOW package that allows MODFLOW to simultaneously evaluate transient water flow in both unsaturated and saturated zones. The package is based on incorporating parts of the HYDRUS‐1D model (to simulate unsaturated water flow in the vadose zone) into MODFLOW (to simulate saturated groundwater flow). The coupled model is effective in addressing spatially variable saturated‐unsaturated...
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Nuclear Power Plant Steam Turbine - Modeling for Model Based Control Purposes
PublicationThe nature of the processes taking place in a nuclear power plant (NPP) steam turbine is the reason why their modeling is very difficult, especially when the model is intended to be used for on-line optimal model based process control over a wide range of operating conditions, caused by changing electrical power demand e.g. when combined heat and power mode of work is utilized. The paper presents three nonlinear models of NPP steam...
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Wear of electroplated diamond tools in lap-grinding of Al2O3 ceramic materials
PublicationCurrent development of modern products, together with ever-increasing demands for their operation and usage, necessitate the search for new processing methods. Abrasive machining is widely used in many industrial areas, especially for processing difficult-to-machine materials such as advanced ceramics. Grinding with lapping kinematics, also called lap-grinding, is still one of the innovative methods of abrasive processing being...
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Nested Kriging with Variable Domain Thickness for Rapid Surrogate Modeling and Design Optimization of Antennas
PublicationDesign of modern antennas faces numerous difficulties, partially rooted in stringent specifications imposed on both electrical and field characteristics, demands concerning various functionalities (circular polarization, pattern diversity, band-notch operation), but also constraints imposed upon the physical size of the radiators. Conducting the design process at the level of full-wave electromagnetic (EM) simulations, otherwise...
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Medially positioned plate in first metatarsophalangeal joint arthrodesis
PublicationObjective The purpose of this study was to biomechanically compare the stability of first metatarsophalangeal (MTP1) joint arthrodesis with dorsally and medially positioned plates. Methods A physical model of the MTP1 joint consists of printed synthetic bones, a titanium locking plate and screws. In the experiments, samples with dorsally and medially positioned plates were subjected to loading of ground load character in a universal...
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Determinants of the incidence of non-academic staff in European and US HEIs
PublicationIn this article, we contribute to the scant literature covering quantitative studies on the determinants of the non-academic staff incidence in higher education institutions by analysing how the proportion of non-academic staff is related to key features such as size, prestige, year of foundation and financial structure of universities. We apply nonlinear regression analysis to compare HEIs across Europe and the USA, taking into...