The Experts below are selected from a list of 222 Experts worldwide ranked by ideXlab platform
O. I. Hryhorchak - One of the best experts on this subject based on the ideXlab platform.
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An application of a quantum wave Impedance method to finite periodic structures
arXiv: Quantum Physics, 2020Co-Authors: O. I. HryhorchakAbstract:The relations between a quantum wave Impedance Function and elements of transfer and scattering matrixes for quantum mechanical systems with arbitrary localized form of potential were established. Obtained results allows using the advantages of both methods, namely a transfer matrix technique and a quantum wave Impedance approach, for an investigating of nanosystems with a complicated geometry of a potential. A finit Dirac comb was solved and expressions for Tamm's levels in this system were derived within both approaches.
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Reformulation of a transmission and reflection problems in terms of a quantum wave Impedance Function.
arXiv: Quantum Physics, 2020Co-Authors: O. I. HryhorchakAbstract:On the base of a 1D Shr\"{o}dinger equation the non-linear first-order differential equation (Ricatti type) for a quantum wave Impedance Function was derived. The advantages of this approach were discussed and demonstrated for a case of a single rectangular barrier. Both the scattering and the bound states problem were reformulated in terms of a quantum wave Impedance and its application for solving both these problems was considered. The expressions for a reflection and a transmission coefficient were found on the base of a quantum wave Impedance approach.
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An application of a quantum wave Impedance approach for solving a nonsymmetric single well problem
arXiv: Quantum Physics, 2020Co-Authors: O. I. HryhorchakAbstract:A short introduction of a relation between a Green's Function and a quantum wave Impedance Function as well as its application to a determination of eigenenergies and eigenFunctions of a quatum-mechanical system is provided. Three different approaches, namely a classical approach based on a direct solving of a Shrodinger equation, a transfer matrix method and a quantum wave Impedance technique, for a calculation of eigenenergies and eigenFunctions of a quantum mechanical nonsymmetric single well system are considered. A comparision of these approaches gives the possibility to clarify advantages and drawbacks of each method which is useful especially for teaching and learning purposes.
Masato Saitoh - One of the best experts on this subject based on the ideXlab platform.
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A one‐dimensional lumped parameter model representing Impedance Functions in general structural systems with proportional damping
International Journal for Numerical Methods in Engineering, 2011Co-Authors: Masato SaitohAbstract:SUMMARY This paper presents a one-dimensional lumped parameter model (LPM) that accurately represents the Impedance Function between two nodes arbitrarily selected in general linear structural systems having proportional damping. Through a procedure based on the modal analysis, the Impedance Function can be transformed into an equivalent LPM consisting of units arranged in series, with each unit consisting of a spring, a dashpot, and a so-called gyro mass element arranged in parallel. The gyro mass element generates a reaction force proportional to the relative acceleration of the nodes between where it is placed. Three application examples show that the LPMs accurately simulate the Impedance Functions in a mass–spring structure, a truss frame structure, and a cantilever plate. For a more efficient representation, a large number of units associated with high-order modes in the high-frequency region can be removed from the proposed gyro mass LPM (GLPM) as an approximation of the Impedance Functions in a target frequency region. The accuracy of the approximated GLPMs is improved by incorporating an additional unit associated with residual stiffness. This approximation greatly reduces the number of degrees of freedom of the GLPMs so that a marked decrease in the computational domain size and time can be expected for solving dynamic problems. Copyright © 2011 John Wiley & Sons, Ltd.
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Lumped parameter models representing Impedance Functions at the end of a finite beam on a viscoelastic medium
Computers & Structures, 2011Co-Authors: Masato SaitohAbstract:This study presents a lumped parameter model that represents Impedance Functions at the end of a finite flexural beam on a viscoelastic medium. This model comprises units arranged in series, each of which consists of a spring, a dashpot, and a so-called ''gyro-mass element.'' A formula is presented for determining the properties of the elements in the units. The Impedance Function simulated by the proposed model shows good agreement with the rigorous Impedance Function. A significant reduction in the degrees of freedom is a major advantage of this model for solving recent vibration problems.
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Lumped parameter models representing Impedance Functions at the interface of a rod on a viscoelastic medium
Journal of Sound and Vibration, 2011Co-Authors: Masato SaitohAbstract:Abstract In this study, a lumped parameter model that properly simulates the Impedance characteristics at the extremity of a uniform, isotropic, homogeneous rod on a viscoelastic medium is proposed. The lumped parameter model consists of springs, dashpots, and so-called “gyro-mass elements”. The gyro-mass elements generate a reaction force proportional to the relative acceleration of the nodes between which they are placed. This model consists of units arranged in series, each unit consisting of a spring, a damper, and a gyro-mass element arranged in parallel. A formula is proposed for determining the properties of the elements in the units calculated from a closed-form solution based on a modal expansion. The Impedance Function simulated by the proposed model shows good agreement with the rigorous Impedance Function derived from the differential equation of motion of the rod. The results obtained by employing this model in some example applications show that the accuracy of the model is appreciably high when compared with conventional finite element models. A great advantage of this model is that a significant reduction of the number of degrees of freedom can be achieved for solving recent vibration problems with high-frequency excitations, such as ultrasonic vibrations.
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Equivalent One-Dimensional Spring-Dashpot System Representing Impedance Functions of Structural Systems with Non-Classical Damping
Cmes-computer Modeling in Engineering & Sciences, 2010Co-Authors: Masato SaitohAbstract:This paper describes the transformation of Impedance Functions in general structural systems with non-classical damping into a one-dimensional spring-dashpot system (1DSD). A transformation procedure based on complex modal analysis is proposed, where the Impedance Function is transformed into a 1DSD comprising units arranged in series. Each unit is a parallel system composed of a spring, a dashpot, and a unit having a spring and a dashpot arranged in series. Three application examples are presented to verify the applicability of the proposed procedure and the accuracy of the 1DSDs. The results indicate that the 1DSDs accurately simulate the Impedance Functions for a spring-dashpot-mass structure, a truss frame structure, and a plate structure. The 1DSD transformation offers compatibility with complex modal analysis: a large number of units associated with high modes beyond a target frequency region can be removed from the 1DSDs as an approximate expression of Impedance Functions. The accuracy of the approximated 1DSDs can be improved by incorporating an additional unit associated with the residual stiffness that compensates for the effect of high modes. A marked decrease in the computational domain size and time with the use of the 1DSDs is of great scientific and engineering importance in diverse technological applications.
Shengchuan Zhao - One of the best experts on this subject based on the ideXlab platform.
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Urban Road Traffic Impedance Function—Dalian City Case Study
Journal of Highway and Transportation Research and Development (English Edition), 2014Co-Authors: Shengchuan ZhaoAbstract:The typical U.S. Bureau of Public Roads (BPR) volume-delay Function is modified to construct the more suitable model to China’s road traffic situation. Factors influencing road traffic Impedance, such as the number of lanes, speed limit, intersection density, bus stop density, saturation and congestion are considered. On the basis of actual data collected from different main roads in Dalian city, traffic Impedance Functions for different road types (expressway, trunk road, secondary trunk road and slip road) are calculated using SPSS software. The results analysis of the traditional and improved BPR volume-delay Functions is compared to certify the useful improved BPR volume-delay Function. To apply road traffic Impedance to the traditional four-step model, the authors calculate the daily conversion coefficients. These reflect the relationship between hourly traffic Impedance and daily Impedance Function and suggest the suitable usage of daily conversion coefficients in further research.
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Discussion on Influencing Factors of Free-flow Travel Time in Road Traffic Impedance Function☆
Procedia - Social and Behavioral Sciences, 2013Co-Authors: Shengchuan ZhaoAbstract:Road traffic Impedance is an important part of traffic assignment and has a direct impact on urban transportation planning, especially on the optimization of the urban road network. The Bureau of Public Roads (BPR) Function has been the classical traffic Impedance since the 1960s, which pays more attention to the link level. This paper aims to construct an improved BPR Function based on the influencing factors of road traffic Impedance, such as the density of intersections, the density of bus stops, non-motor vehicles and saturation. These factors can reflect the difference between road and link. The real data collection from different roads in Dalian are used to calculate the road traffic Impedance Function by the SPSS software. The results show that the density of intersections, the density of bus stops and saturation have positive effects on unit travel time in Dalian roads. These results not only point out the necessary influencing factors, but also validate the correctness of the proposed Impedance Function. In summary, this Function has a simple structure and high flexibility so that it is expected to be transplanted to other cities.
Xu Jingcui - One of the best experts on this subject based on the ideXlab platform.
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Research on Road Network Accessibility Based on Time Impedance Function
Progress in geography, 2008Co-Authors: Xu JingcuiAbstract:The paper elaborates the accessibility concept and application scope in the different disciplines simply,analyzes the factors influencing accessibility,summarizes quantification method used commonly at the present stage in geometry topology,points out application conditions and insufficiency of the gravity model,the distance model,the accumulation opportunity method.In this foundation,discovers that quantification limiting to the spatial criterion can not respond the relation of the spatial network accurately,in view of this question,proposes the quantification model basing on the time Impedance Function,which takes the main variable by the practice capacity.This model can respond the spatial demand intensity indirectly.Then the paper introduces the node importance concept,it can reflect factors influencing accessibility in the road network even more directly,such as society,economy,transportation.This model can make up for the insufficiency of space and time method.
Francisco Vicente - One of the best experts on this subject based on the ideXlab platform.
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Analysis of an Impedance Function of zinc anodic dissolution
Journal of Electroanalytical Chemistry, 2004Co-Authors: David Giménez-romero, José Juan García-jareño, Francisco VicenteAbstract:Zinc anodic dissolution has been studied by means of electrochemical Impedance spectroscopy (EIS). The kinetic study of the oxidation mechanism has allowed us to propose a theoretical Impedance Function for this system in deaerated sulphate medium. Relevant information on the faradaic process is provided by analysis of the theoretical Impedance Function. Kinetic parameters of this system can be calculated from the fitting of experimental data to the faradaic Impedance Function deduced theoretically. The physical measurements of this Function are analysed by means of the dependence of simulated EIS spectra on kinetic parameters.
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Singular points of electrochemical Impedance Function
Applied Surface Science, 2004Co-Authors: José Juan García-jareño, David Giménez-romero, Francisco VicenteAbstract:A model of EIS response for a system with two consecutive monoelectron transfers is developed in this work. Relevant information on the mechanism of these electrochemical systems is provided by the parametrical identification of the theoretical faradaic Impedance Function. The kinetic parameters of this model are easily calculated through the calculus of the characteristic points of this Function. This calculus allows to interpret the metals anodic dissolution according to the reaction mechanism and, therefore, allows us to establish easily the kinetic and thermodynamic behaviour of these systems with respect to any experimental parameter.
