bluuebunny/crossref_metadata_2025 huggingface dataset:
Study on a new type micro-stirrer excited by longitudinal elastic wave for thrombus dissolution
Authors: Ajoudanian Mohammad , Jiang Zhongwei , Morita Minoru
Published: December 2018

This paper presents the fundamental study on design of a novel micro stirrer for high effective dissolution of cerebral thrombus or blood clot. The actuator is a beam with supported one side and the other side is free. The longitudinal waves excited by a transducer from support side, travel through a beam and before reaching the tip of beam partially impinge to a slant surface. So that some of the energy of the incident longitudinal waves are reflected with different orientations from the length direction. The other energy would be converted to shear waves. Despite the elongation and bending at tip, there is no significant bending across other part of beam. The micro stirrer was evaluated by vertical tip displacement in varied mode shape with using FEM analysis. The obtained results demonstrated that the vertical motion of the stirrer at desired mode shape was less influenced by the length of actuator. Due to the attenuation of wave amplitude, a driving technique method is proposed to generate high-amplitude.
Negative permeability frequency conditioning for two-component metamaterial media with ferrite like metal inclusions
Authors: Rybin Oleg
Published: December 2018

In the paper, the possibility of achieving negative permeability for two-component metamaterials is analytically proven. The metamaterial media are presented as an infinite host dielectric material (air) with periodically embedded ferric cylindrical and spherical inclusions saturated with a biasing external magnetic field. The appropriate frequency-dependent inequalities are obtained in the frequency range where permeability becomes negative. The cases when electromagnetic wave propagates parallel and transverse to the direction of biasing magnetic field are studied.
Dynamics of rails for electromagnetic railguns
Authors: Xu Lizhong , Geng Yanbo
Published: December 2018

One of the important problems in developing the railgun is design of the rail and the related elements. The evaluation of the loads on rails is an important task. On operation, the armature runs at an acceleration. The acceleration load can cause more complicated dynamic responses of the railgun. Here, the dynamic equation of the rail for the railgun is given, and the equations for the forced responses of the rail under constant velocity load and the acceleration load are developed. Using these equations, the dynamic displacement responses of the rail to the running electromagnetic force for various accelerations are investigated. The results show that the maximum dynamic displacement peak of the rail and its position depends on the boundary conditions and the acceleration of the running armature. The larger is the acceleration, the more obvious is the increase of the dynamic displacements under condition that the armature velocity is above the critical velocity. For a given acceleration, the effects of the damping on the dynamic displacements of the rail become more obvious when the armature velocity grows. The results are useful for design and application of the railgun system.
Mode competition and control in a 170∼GHz gyrotron cavity for ECRH application
Authors: Singh R.K.
Published: December 2018

The present paper is devoted to the study of mode competition and control in a 170 GHz gyrotron cavity for potential application in electron cyclotron resonance heating (ECRH) of plasmas. An extensive analysis has been carried out for coupling coefficient, start oscillation current, voltage depression, and limiting current for the candidate modes in the gyrotron cavity resonator. The study reveals that the main competing modes for TE _{28,8}^{-} come from TE _{25,9}^{+} and TE _{27,8}^{-} . The optimum beam position for TE _{28,8}^{ - } mode is found to be at 8.28 mm. To avoid excitation of competing modes, it has been found that slight increase in electron beam radius from 8.28 mm to 8.40 mm avoids the excitation of all the competing modes. Based on the considerations of coupling coefficient, start oscillation current, voltage depression, and limiting current; the TE _{28,8}^{-} mode is selected as the operating mode.
Influences of compressive stress on the narrow hysteresis and piezomagnetic coefficient for the <110> oriented Tb_{0.27} Dy_{0.73} Fe_{1.95} alloys at high drive levels
Authors: Zhao Pei , Zhang Xingyi , Liang Yirui , Zhou Youhe
Published: December 2018

In this paper, the influences of compressive stress on the narrow hysteresis (magnetostriction hysteresis, W_h ) and maximum piezomagnetic coefficient ( d_{33}^{Max} ) of the <110> oriented Tb _{0.27} Dy _{0.73} Fe _{1.95} polycrystalline alloys have been investigated at high drive levels. The simultaneous measurements of magnetostriction and magnetization are carried out as a function of applied magnetic field 0 < H < 800 kA/m and compressive stress 0 to 50 MPa. The results show that the magnetostriction increases sharply in the low and/or moderate magnetic field, and than gains its saturation slowly with increase of the applied magnetic field. However, according to increase of the compressive stress, the magnetostriction decreases in the low and moderate magnetic field, while the saturation magnetostriction(λ _s ) increases. Specifically, λ _s increases from 1143 × 10 ^{ - 6} to 1778 × 10 ^{ - 6} when the compressive stress increases from 0 to 50 MPa and W_h increases from 7.90 to 27.22 kA/m at the same conditions. In addition, the characteristics of d_{33}^{Max} are reported under varied compressive stresses. It is found that the higher compressive stress the lower is d_{33}^{Max} , while at a fixed compressive stress, d_{33}^{Max} in the forward magnetostriction process is lower than that in the reversal magnetostriction process. These results presented are available for a kind of Tb-Dy-Fe alloys applications.
Design and performance analysis of a magnetorheological fluid damper for drillstring
Authors: Zhu Xiaohua , Lai Chunlin
Published: December 2018

To mitigate the severe drillstring vibration during oil and gas drilling, this paper presents a design of mixed mode magnetorheological (MR) fluid damper based on the electromagnetic finite element analysis and Bingham plastic model. The 2D axisymmetric finite element model has been established, and a structural optimization method on the base of magnetic circuit design has also been put forward. The effects of structural parameters such as the radius of bobbin, the thickness of cylinder and the active bobbin length on the flux density inside the fluid gap have been analyzed, which consequently obtain the appropriate design with a higher and more even magnetic intensity. Besides, this analysis has found the relations between damping force, amplifying factor and vibration velocity under different field currents by a typical Bingham plastic model and test data when considering the negative effects of temperature on MR fluid, finally, made prediction on the performance of the MR fluid damper. The main research of the paper lays an important foundation to develop control strategy of the MR fluid damper for drillstring.
Magnetic vector potential and magnetic field intensity due to a finite current carrying cylinder considering a variable current density along its axial dimension
Authors: Díaz Guillermo A. , Mombello Enrique E. , Stephan Voss
Published: December 2018

With the aim of introducing a computationally efficient solution for problems such as the fast computation of magnetic field magnitudes and forces in coils and windings, this paper presents analytical expressions for the magnetic vector potential and magnetic field intensity in radial and axial directions due to a finite cylinder with infinitesimal wall thickness carrying a linearly varying current density between the values at the lower and upper ends. All expressions have been derived in terms of complete elliptic integrals of first, second and third kind, whose evaluation is achieved by means of very fast algorithms. The formulas presented make possible the fast computation of magnetic field at any point in space at reduced computational cost. The formulation is not only specially suited for modeling the current distribution in foil windings of power transformers but also for representing the magnetization of transformer core legs. The present method is also useful for efficient modeling of cylinders with constant current density since it is a generalization of this especial case. Finally, an example is presented where the results achieved using the proposed method are compared with those obtained using the finite element method showing a very good agreement between them.
Alumina filled silicone nanocomposites for electrical insulation of power rotating machines
Authors: Amendola E. , Lupò G. , Petrarca C. , Scamardella A.M.
Published: December 2018

In the present paper, we report results about the preparation and the morphological, thermal, mechanical and electrical characterization of new materials for the impregnation of rotor and stator windings of medium power traction motors. These new materials are obtained by the addition of nano-sized alumina (Al _{2} O _{3} ) fillers to commercially available silicone resin. Their measured physical properties are compared with those of the unfilled matrix, used as a reference, and the influence of the weight concentrations, ranging between 1 wt % and 7 wt % is fully discussed.
An quantum-inspired evolutionary algorithm applied to design optimizations of electromagnetic devices
Authors: Zhang Wei , Xu Hailiang , Bai Yanan , Yang Shiyou
Published: December 2018

To eliminate the deficiency of traditional evolutionary algorithms in numerical implementations with respect to the three key operators such as selection, crossover and mutation operators, a new evolutionary algorithm based on probabilistic models, the quantum-inspired evolutionary algorithm (QEA), is studied for design optimizations of electromagnetic devices. In the proposed QEA, an adaptive update formulation is proposed for the rotation angle to balance the exploration and exploiting searches while the two level information sharing is simplified to one level one to facilitate the implementation of the proposed algorithm. Also, a new information sharing mechanism is introduced. The proposed algorithm is evaluated on an engineering inverse problem with promising results.
Estimation of a surface current distribution from 2D magnetic field measurements
Authors: Nguyen T.A. , Joubert P.-Y. , Lefebvre S. , Chaplier G.
Published: December 2018

The paper reports on the estimation of the distribution of currents flowing in a metalized part, starting from two-dimensional maps of the magnetic field induced above the part, with the monitoring of power semiconductor dies in view. The estimation is obtained from the measured data by inverting a mesh-free modeling of the induced magnetic field. First inversion results of experimental data are presented and discussed.
Electromagnetic modeling of fatigue cracks in plant environment for eddy current testing
Authors: Uchimoto Tetsuya , Takagi Toshiyuki , Ohtaki Keitaro , Takeda Yoichi , Kawakami Akira
Published: December 2018

This study discusses the electromagnetic modeling of fatigue cracks in plant environment to improve accuracy of depth sizing with eddy current testing. For the purpose, the factors that influence eddy current signals of fatigue cracks are evaluated. Here, martensitic layer and oxide fillings in fatigue cracks are focused on as influencing factors, and oxides are systematically filled in fatigue cracks by thermal treatment. The measured EC signals change depending on the presence and type of filling oxides. Numerical simulations are conducted to discuss the electromagnetic modeling of cracks with oxide fillings. The types of oxides in the cracks are identified by Raman spectroscopy, and the martensitic layers in vicinity of crack faces are observed by magnetic force microscopy. These results support for the electromagnetic model of environmental fatigue cracks developed in this study.
Pulsed eddy current thermography for corrosion characterisation
Authors: Tian Gui Yun , He Yunze , Cheng Liang , Jackson Paul
Published: December 2018

Corrosion characterisation on metal substrates is a major problem in the field of corrosion science and Non-destructive Evaluation (NDE). In this work, the electromagnetic NDE method, Pulsed Eddy Current (PEC) Thermography, has been applied to evaluate the corrosion on the mild steel plates. By analysis of heat induction and heat diffusion, early stage thermal images are proposed to avoid the lateral heat diffusion and to detect the corrosion progression more accurately. Principal Component Analysis (PCA) is used to extract the variation information from the different time period image sequences to improve the imaging quality and to validate the early detection theory. Results show that PEC thermography has potential as a rapid tool for corrosion characterisation.
Experimental eddy current measurements of flawed edges compared with results from probabilistic numerical models
Authors: Cherry Matthew , Knopp Jeremy , Blodgett Mark , Grandhi Ramana
Published: December 2018

Eddy current detection of flaws in edges presents challenges in experimental procedures during benchmark studies in the laboratory for model validation as well as practical implementation of a real world detection system. These difficulties result in distortions to the signal that mask the effects from the flawed region itself. Rather than attempting to perfect the experimental setup, we propose to make the numerical models more robust by incorporating randomness in the experimental procedure with uncertainty quantification methods. We present the motivation for the specific method chosen, the probabilistic collocation method (PCM), and the mathematical development behind the method, and then present the results from numerical simulations with a validation measure.
Fabrication of imitative stress corrosion cracking specimen using lithography and solid state bonding
Authors: Yusa Noritaka , Hashizume Hidetoshi
Published: December 2018

This study proposes a method to fabricate artificial flaws whose response to non-destructive testing, especially electromagnetic non-destructive testing, is the same as that of stress corrosion cracking. Stacked metallic films containing through-grooves are sandwiched between metallic blocks and then bonded using solid state bonding. The profiles of the through-grooves are accurately controlled with the aid of the lithography technique, which allows a three-dimensional discontinuity to be embedded inside a material. Since the spatial distribution of the discontinuity is small compared to the spatial resolution of non-destructive testing methods, the method allows the response of stress corrosion cracking to be simulated. Specimens are fabricated using type 316 L austenitic stainless steel, and validated using eddy current testing.
Modeling of thin conductive and magnetic layers in eddy current testing by overlapping finite elements
Authors: Zaidi H. , Santandrea L. , Krebs G. , Le Bihan Y. , Demaldent E.
Published: December 2018

In this paper a new field of application of the overlapping finite element method is proposed for eddy current testing. This method, which has already been used to deal with the lift-off, is extended to the treatment of thin conducting and/or magnetic layers.
Fast diagnosis of transmission lines using neural networks and principal component analysis
Authors: Smail M.K. , Le Bihan Y. , Pichon L.
Published: December 2018

A fast diagnosis dedicated to embedded transmission lines and based on time domain reflectometry is presented. The forward problem allows to simulate the propagation along the wiring network as well as to create datasets for the inverse problem resolution. Neural networks (NNs) are used to solve the inverse problem which consists to find defects on the wire from the reflectometry response. The significant parameters of the reflectometry response data are extracted using principal component analysis. This method allows an efficient reduction of the dimension of the reflectometry data space.
A novel artificial sphincter for functional assist to human puborectalis
Authors: Wu Yue , Wang Minghui , Luo Yun
Published: December 2018

Patients with fecal incontinence suffer both physically and psychosocially. Puborectalis helps with continence, and dysfunction of this muscle may cause fecal incontinence. Though some medical treatments have been introduced, little work has been done on functional assist device to puborectalis. This paper presents a design of a functional assist device to human puborectalis with Ti-Ni shape memory alloy as the actuating part, and evaluates its deformation and mechanical properties. The effectiveness of this device was confirmed by preliminary experiments conducted at body temperature.
Active loading machine using MR fluid clutch for leg rehabilitation system
Authors: Nakano Hiroshi , Nakano Masami
Published: December 2018

A new conceptual loading machine using a magneto-rheological fluid(MRF) clutch has been proposed and developed to be used for evaluation and training system of muscle strength in leg rehabilitation. This loading machine, which is called MRF active loading machine, mainly consists of a newly designed MRF clutch and a reversible induction motor with an electromagnetic shaft locking device. In this paper, the total construction design of the MRF active loading machine and the detail of the MRF clutch design are described, based on the usages for leg rehabilitation and electromagnetic field analyses, and the performances of the clutch are discussed. And also, the several usages of the MRF active loading machine are proposed.
Influence of work hardening on the performance of stents
Authors: Wang Ming , Ma Quanchao , Zhang Wenguang , Luo Yun
Published: December 2018

The material properties of stents change with that of deformation due to work hardening. The whole deformation procedure of balloon expandable stent is a typical nonlinear process. Therefore, simplified procedures were applied in designing and optimizing stents with finite element method, typically omitting the process of stent crimping. In fact, plastic deformation and work hardening may occur during crimping, which may result in changes of material properties and affect the performance of stents. In this paper a complete deformation procedure of two typical stents was simulated using finite element method. Their mechanical performances were evaluated and compared with those simulations using a simplified procedure (omitting the process of stent crimping). It was found that the work hardening caused by crimping has a significant influence on the stress distribution, recoil rate and the maximum expandable diameter of stent.
Design and optimization of uniplanar EBG structures
Authors: Assimonis S.D. , Yioultsis T.V. , Rekanos I.T. , Kriezis E.E. , Antonopoulos C.S.
Published: December 2018

Electromagnetic bandgaps (EBG) are periodic formations, inspired by photonic crystals, exhibiting prohibited frequency bands for electromagnetic wave propagation. The uniplanar EBG is particularly assessed, due to its fabrication simplicity and is found to exhibit a propagation mode that cancels the desired bandgap behaviour. Two new planar EBG structures, without such modes are presented, retaining the distinct feature of easy fabrication, since the metallic structures are exclusively on the interface layers, with no vertical connections. The EBGs are optimized to maximize the bandgap, making them suitable for the design of wideband microwave circuits and antennas.
Improved framework for Monte Carlo numerical evaluations in field interference problems
Authors: Ceclan Andrei , Ţopa Vasile , Micu Dan D. , Czumbil Levente , Şimon Anca , Creţ Octavian
Published: December 2018

This paper presents an alternative framework for computing the electric potential in (non)homogeneous media using a Monte Carlo-based method. The implementation relies on the use of FPGA to improve the computational speed. Compared to the previous software implementations, this approach allows increasing the variation range of all parameters involved in the computation, thus yielding more accurate and faster results. The obtained computation time is more than one order of magnitude less than classical software solutions.
Max-min K-means clustering algorithm and application in response signal feature extraction
Authors: Wang Cheng , Bai Junqing , Li Jiaojiao , Dong Longlei , Yan Guirong , Sun Zengguo
Published: December 2018

In order to overcome the problem of classical K-means clustering algorithm, such as sensitiveness to its initial cluster centers selection and easiness of falling into local optimization, this paper proposed max-min K-means clustering algorithm. The algorithm adopts max-min principle to determine initial cluster centers of K-means clustering algorithm. Comparison of clustering effects of the new method with that of muilt-restart K-means clustering algorithm on artificial data set showed the better effect and the greater excellence of max-min principle. Then, the max-min K-means clustering algorithm was applied to analyze vibration response signal of cylindrical shell automatic in order to discover space distribution feature of dynamics response. Clustering results tallied with feature of dynamic response of cylindrical shell, which validated the effectiveness and reasonableness of the new clustering method itself.
Spectral stochastic finite element method for solving 3D stochastic eddy current problems
Authors: Beddek K. , Clénet S. , Moreau O. , Le Menach Y.
Published: December 2018

In this paper, a spectral stochastic finite element method (SSFEM) is described and applied to quantify uncertainties in an industrial eddy current non destructive testing (NDT) problem. A new iterative solver based on the fixed-point method is proposed to solve the large scale linear system. The efficiency of the suggested iterative solver to tackle the SSFEM computational complexity is demonstrated. The SSFEM results and the computation times obtained with 2 and 4 random variables are compared to those given by the anisotropic adaptive sparse grid non intrusive spectral projection (NISP). On this application, the SSFEM dedicated solver is competitive with the adaptive sparse grids strategy.
A study on the design parameters of inductive power transformers
Authors: Park Chan-Bae , Lee Hyung-Woo , Lee Byung-Song
Published: December 2018

As a new concept of energy transmission systems, evolved from existing catenary and pantograph methods, Inductive Power Transformer (IPT) systems have been studied in a variety of applications in the field of railway systems recently, but there are still a lot of technical issues to resolve in order to apply an IPT system to a large system such as high-speed railway. Equivalent circuit parameters and coupling coefficients of IPTs are important design factors for high energy transfer efficiency. This paper investigates the properties of equivalent circuit parameters and coupling coefficients of the U-U type IPT and U-I type IPT using analytical and experimental methods.
Investigation on the performance of the single-phase LSPM motor for variable capacity type compressor
Authors: Rhyu Se-Hyun , Lee Jeong-Jong , Kim Young-Kyoun , Kim Byung-Taek , Kim Dae-Kyong
Published: December 2018

This paper investigates the performance of the line start permanent magnet (LSPM) motor which needs a high efficiency characteristic in a wide operation region. LSPM motor's performance indexes, such as efficiency, motor current, load angle and synchronous torque, have complex relationship with each other according to the main and auxiliary windings distribution, and the selection of running capacitor. The output characteristics can be defined by the winding structure which is calculated by d-q equivalent circuit and finite element method. The efficiency characteristic is verified by simulation as well as by experiment on the designed LSPM motor. From the results, we show that the redesigned model considering the winding structure and capacitor matching has a wide operating region.
Numerical simulation of the electromagnetic-vibration of a gyroscope motor
Authors: Yang Baokun , Zheng Hongbing , Yan Guirong
Published: December 2018

A gyroscope motor is a precision component widely used in aerospace, aviation and other fields. Its accuracy is very sensitive to vibration. Vibration can also cause changes in the air-gap magnetic field in addition to changes due to the electromagnetic force. This paper presents a numerical simulation method for analyzing the electromagnetic characteristics of the gyroscope motor air gap subject to the coupled electromagnetic force and mechanical vibration. It analyzes the magnetic field in the gap in the axial and circumferential directions using a finite element method model, and then analyzes the magnetic characteristics of the gyroscope motor air gap subject to the coupled electromagnetic force and vibration. The method can be used to estimate the electromagnetic vibration to optimize the design of a gyroscope motor and extend its life.
Time response properties on deformation velocity for a solid polymer electrolyte sensor
Authors: Otsuki Manabu , Okuyama Takeshi , Tanaka Mami
Published: December 2018

This paper aims to clarify time response properties of a solid polymer electrolyte (SPE) sensor. SPE film has been attracted attention in wide range of fields, and it is expected to be used as soft actuators and sensors. SPE film can reversely convert electrical energy into mechanical energy. Moreover, SPE film is lightweight, flexible, and has good workability and air-stable output. Although authors have been investigated output characteristics of an SPE sensor, time response properties of the sensor have not been inspected. In the paper, to reveal time response properties of the SPE sensor, the sensor output behaviors for several deformation velocities are measured and evaluated. Maximum voltages in the transient response and output attenuations for constant deformation are analyzed. Results show that the attenuation characteristics depend on the sensor deformation velocity, and maximum voltages in the transient response are independent of deformation velocities.
Dynamic ball and plate control verification on magnetic suspension platform using enforced fuzzy logic control
Authors: Lin Chin E. , Huang Wei Cheng
Published: December 2018

This paper presents an enforced fuzzy logic control (EFLC) implementation on a ball and plate system (B&P) for dynamic control verifications. A two degree-of-freedom (DOF) platform is constructed for experiments using hybrid magnetic suspension (MS) actuators. The EFLC adds an enforcing rule to buffer the running ball to approach the target. It reduces the overshoot, shortens the settling time, and improves the overall performance significantly. The mathematical model of the ball and plate operation is derived through the Euler-Lagrange equation. Using a commercial touch panel as position sensor, a microprocessor controller is implemented on the proposed system to generated Pulse Width Modulation (PWM) control signals to activate the MS actuators. The tests verify the random position tracking and trajectory tracking performance on the MS B&P with different conditions. This proposed system could be applied to prevent turn over as an active device in transportation field.
Analytical solution of MHD micropump with circular channel
Authors: Moghaddam Saied
Published: December 2018

An analytical solution is found for equations of AC and DC-operated MHD micropump with circular channel. The kind of fluid is Newtonian and the flow generated by the Lorentz force is assumed to be laminar, unidirectional, and one-dimensional. The effect of Hartman number and radius is studied on the velocity and volumetric flow rate profiles and a relation for optimum Hartman number and radius which causing maximum volumetric flow rate is found. Finally DC-operated MHD micropump is compared with AC-operated.
Coupled electromagnetic, thermal and elastic–plastic simulation of multi‐impulse inductive heating
Authors: Pantelyat Michael G.
Published: December 2018

The coupled electromagnetic, thermal and elastic–plastic field simulation is described for new technological processes of multi‐impulse inductive heating of metal. An iterative algorithm, taking into account the special features of multi‐impulse inductive heating, has been developed. The algorithm consists in the solution of the eddy current problem for one impulse and in the extension of the obtained distribution to a number of next impulses. Thermal and mechanical fields are determined for a series of the impulses using the increased value of the time step and the time average distribution of the heat sources. This paper presents the detailed description of the numerical technique and of the obtained results concerning real technological processes.
Plane wave diffraction by a perfectly conducting strip in a homogeneous biisotropic medium
Authors: Asghar S. , Hayat Tasawar
Published: December 2018

The diffraction of an electromagnetic plane wave by a perfectly conducting strip in a biisotropic medium is considered. The problem is solved by using the Wiener–Hopf technique and the asymptotic methods. The diffracted field is shown to be the sum of a field produced by the two edges of the strip and a field due to the interaction of the two edges.
Use of deterministic methods and finite elements for the solution of 3D shape optimization problems in electromagnetics
Authors: Ramirez J.A. , Freeman E.M.
Published: December 2018

This work is concerned with the automatic design of electromagnetic devices in 3D using numerical methods, i.e., deterministic methods coupled with finite elements (FE). In particular this work considers the choice of deterministic methods, limitations concerning the number of variables, convergence, CPU time and choice of potentials for the field analysis. Two different approaches are considered for the sensitivity analysis, the direct differentiation of the FE matrices and the adjoint variable method. The FE formulation uses the magnetic vector potential for domains with current densities and the scalar potential for domains in which current densities are not present. The results of two static problems are presented. In general, the increase in the number of variables, from 2D to 3D, did not represent a major problem for the convergence of the methods studied. In terms of CPU time, the sequential quadratic programming method performed better than the augmented Lagrange multiplier method. Both sensitivity analysis methods investigated proved to require similar field calculations.
Uniqueness of the inverse scattering problem for a chiral obstacle
Authors: Athanasiadis Christodoulos , Stratis Ioannis G.
Published: December 2018

This paper deals with the inverse scattering problem to determine the shape of a chiral obstacle immersed in achiral free space from the knowledge of the scattered wave. A variational equation is established for the corresponding direct scattering problem. Then, under appropriate assumptions, it is shown that the chiral obstacle is uniquely determined by the far field patterns of all incident waves with a fixed wave number.
The Maxwell and adjoint systems for complex media: Physical significance and applications
Authors: Altman C. , Suchy K.
Published: December 2018

Useful information on the solutions to the Maxwell system of first order linear differential equations may be obtained with the aid of two distinct, but not independent, sets of adjoint equations, the formally adjoint system which reduces to the complex conjugate equations in loss free media, and the Lorentz adjoint system which reduces to the time reversed equations in loss free media. The formally adjoint system is used to define a generalized energy flux vector, to decompose wavefields into constituent modes and to define their amplitudes. The Lorentz adjoint system is used to construct time reversed, “complementary” media, and time reversed wavefields and sources that are Lorentz reciprocal to the given wavefields and sources. In some problems, such as the determination of reciprocal scattering matrices or reciprocal modal Green’s functions, it is necessary to employ both adjoint systems.
Homogenization of linear bianisotropic particulate composite media – Numerical studies
Authors: Michel Bernhard , Lakhtakia Akhlesh , Weiglhofer Werner S.
Published: December 2018

We present here the application of the Maxwell Garnett (MG) and the Bruggeman (Br) formalisms to homogenize very general linear bianisotropic‐in‐bianisotropic particulate composite media with ellipsoidal inclusions. Both formalisms involve the calculation of certain depolarization dyadics, which generally amounts to the numerical evaluation of several two‐dimensional integrals. The MG estimate of the constitutive dyadic of the homogenized composite medium can then be obtained by straightforward matrix manipulations. The Br estimate, however, involves nonlinear equations which have to be solved iteratively. We present an iteration scheme that converged rapidly in most cases tested. Numerical results are given for those composite media for which the Bruggeman formalism so far has not been implemented: spherical chiral inclusions in a uniaxial dielectric host medium, spheroidal chiral inclusions in free space, spherical chiral inclusions in a biaxial dielectric host medium, and spherical voids in a gyrotropic dielectric host medium.
On optical rotation and ellipticity transformation by axially excited slabs of dielectric thin‐film helicoidal bianisotropic mediums (TFHBMs)
Authors: Venugopal Vijayakumar C. , Lakhtakia Akhlesh
Published: December 2018

The tilt angles and the ellipticities of transmitted and reflected plane waves are shown to be different from those of plane waves normally incident on slabs of dissipative dielectric thin‐film helicoidal bianisotropic mediums (TFHBMs). These slabs can therefore function as transformers of vibration ellipses in optical circuits. The transformation properties can be engineered by proper selection of geometric parameters, and can be dynamically controlled by varying the concentration of appropriate fluids in the porous TFHBMs. The true circular dichroism and an apparent circular dichroism are shown to convey different types of information.
Tabu search coupled with deterministic strategies for the optimal design of MRI devices
Authors: Fanni A. , Giacinto G. , Marchesi M. , Serri A.
Published: December 2018

A tabu search based strategy has been developed to achieve design optimisation of electromagnetic structures. Tabu Search (TS) is a metaheuristic that guides the search for the optimal solution making use of flexible memory systems which exploit the history of the search. It consists of systematically prohibiting some solutions to prevent cycling and, at the same time, avoiding to be trapped in local minima, and deeply explores the search space to minimise the objective function. Since the variables to be optimised are continuous in nature, we developed a continuous tabu search algorithm in which the range of variation of each variable is discretised by division into sub-ranges. In this way, it is possible to identify a finite alphabet and apply tabu search strategies. Best performances have been reached by coupling tabu search with other optimisation procedures, such as Golden Search (GS) and a non-linear Simplex (SX) method. The algorithm is compared with more traditional methods on a Magnetic Resonance Imaging (MRI) design problem, showing a good performance improvement.
Tuning of the optimization strategies on the problem size
Authors: Fanni Alessandra , Marchesi Michele , Serri Antonino , Usai Mariangela
Published: December 2018

This paper is concerned with the problem of adapting the optimization algorithms to the dimension of the problem at the hand. As test case, the problem of designing the structure of a magnetic resonance imaging system is considered with different number of optimization variables. A greedy genetic algorithm for continuous variables electromagnetic optimization problems, already presented in literature, has been modified to consider different problem sizes. A detailed comparison of performances obtained implementing several strategies and tuning of optimization parameters is eventually presented.
Seeking the optimal arrangements of overhead power line conductors with conductor sagging consideration
Authors: Deželak Klemen , Štumberger Gorazd
Published: December 2018

This work deals with a new method that determines the optimal arrangements of overhead power line conductors by an optimization method called Differential evolution. During the optimization procedure the root mean square values of the electric field strength and the magnetic field density on the border of the overhead power line right of way are used as the main criteria. Both, electric and magnetic fields, are evaluated with methods, where the impact of conductor sagging is considered. The position of the each power line conductor is determined in an optimization process. In the given case, the aim of optimization is to find such arrangement of conductors where the values of the electric and magnetic fields on the border of the overhead power line right of way are under the prescribed limits, whereas the tower height is as low as possible.
Electromechanical coupled dynamics of rails for electromagnetic launcher
Authors: Geng Yanbo
Published: December 2018

The railgun system is an electromechanical coupled system. The electromagnetic field may cause an essential change of the dynamic behaviors of the railgun system. Here, considering the changes of the electromagnetic force caused by the rail displacement, the electromechanical coupled dynamic equations for the rail are given. Using these equations, the natural frequencies of the railgun system and their changes along with the system parameters are investigated, the vibration modes of the railgun system are discussed, and the forced responses of the rail to the running electromagnetic force are analyzed. The results show that the moving electromagnetic force causes the changes of the natural frequencies for the railgun system. As the armature moves, the vibration modes of the rail are change as well. The electromechanical coupled effects change the forced responses of the rail to the running electromagnetic load. The effects are more obvious for larger armature distance and current, small distance between the two rails and stiffness of the elastic foundation. The results are useful for design and application of the railgun system.
Robust decoupling control of a three-link robot arm directly driven by permanent magnet synchronous motors
Authors: Zhang Chi , Zhao Guangzhou , Tseng King Jet
Published: December 2018

This paper presents a three-link direct drive robot arm for wafer handling application. This robot arm is directly driven by three permanent magnet synchronous motors which are designed with flat structures and large rated torques. The mechanical structures of the presented robot arm and the PM motors are introduced and their dynamic models are derived. The frequency responses obtained from experimental tests reveal serious coupling effect of the system. A decoupling method based on computed torque control is proposed and the test results validate the effectiveness of this method. Robust SISO controllers are developed to control the PM motors after the decoupling. The experimental results demonstrate satisfying dynamic, settling and static performances with the proposed robust decoupling control.
Sizing of metallic foam bubble flaws using direct current potential drop signals with the help of the neural network method
Authors: Xie Shejuan , Takagi Toshiyuki , Chen Zhenmao
Published: December 2018

To investigate the possibility of reconstructing the position and size of bubble flaws in metallic foam, a Neural Network approach is applied to predict the flaw profile from Direct Current Potential Drop (DCPD) signals. A feed-forward network, improved by Principal Component Analysis (PCA) is selected for the inverse analysis. Over 100 sets of DCPD signals due to flaws with different positions and sizes are calculated using a newly developed fast forward solver and are used for the inverse analysis. Satisfactory reconstruction results are obtained for these simulated signals.
Relations between state and religious institutions in the context of national interests and state security
Authors: Vladychenko Larysa
Published: December 2018

The problem of relations between state and religious institutions is relevant throughout the period of Ukraine's independence. At the heart of building state policy in the field of religion, our state is guided by international norms, which are based on the recognition of the equality of all religions and the maximum promotion of the activities of religious organizations, which in turn is implemented in national legislation
DEPENDENCE BETWEEN THE METHODICAL SYSTEM OF TEACHING INFORMATICS IN SCHOOL AND THE TYPE OF USED SOFTWARE
Authors: Markushevich M. V.
Published: December 2018

Component analysis of the elements of the methodical system of teaching informatics in the secondary school, depending on the type of software used in the educational process (free or proprietary), is carried out. On the basis of the conducted research, the structural scheme of the methodical system of teaching informatics is corrected and a conclusion is formulated about the dependence of the methodical system on the type of software used in training.
STUDYING THE BASIS OF ALGORITHMIZATION BY THE EXAMPLE OF THE TURING MACHINE USING GAME TECHNOLOGY
Authors: Belotserkovskaya I. E. , Vtyurin M. Yu.
Published: December 2018

The article presents detailed solutions of a few algorithmic problems on the example of the Turing machine with a detailed description of the form of work at the lesson. Particular attention is paid to the description of the game learning method “Presenting algorithm as role game in Turing machine”.
Operational Distinctions Between Linux and Windows
Authors: Goyal Khushbu , Ranawat Karan Raj Singh , Nayak Nirjara
Published: December 2018

Today in a computer era there are two most used operating systems i.e. Windows and Linux. Windows is famous for its easy to use interface. Linux, on the other hand provides a ton of inbuilt functionalities to automatize task. To understand which one is superior we are going to compare them on grounds of kernel architectural differences, memory management, respective file systems and CPU scheduling task. These are standard bench-marks on which we are contrasting the internal working of an operating system. Linux and Windows vary in price, viewpoint and adaptability, with both in quest to stabilize in their present flaws.
浅析建设工程质量安全监督管理工作
Authors: 岳 建军
Published: December 2018

当前国家对建筑工程建设质量要求普遍提高,建筑工程质量安全监督管理工作也告别了以往的工作方式,且很多因素都会对建设工程的质量产生十分显著的影响,为了提高工程质量,应不断加大工程质量安全监督管理力度,在保证工程质量的同时,也确保工程的安全性。
试析建筑工程管理及施工质量控制的有效策略
Authors: 曾 繁育
Published: December 2018

如今建筑企业发展势头良好,市场内部的竞争也日益激烈,在建筑工程建设的过程中也出现了较为明显的质量问题,为了提高工程建设的质量,应积极采取有效措施,完善建筑工程管理体系,促进建筑行业的健康发展。
监理工程师的责任风险及防范措施探讨
Authors: 吴 晓宇
Published: December 2018

随着建筑行业的不断发展,我国对于监理工程师的工作也加强了监督工作,因为监理是促进建筑事业发展的基础,同时一旦工作疏忽,也会承担一系列的责任风险,会给监理单位和监理机构的发展造成一定的影响；随着《建筑法》和《建设工程质量管理条例》《建设工程安全生产管理条例》的颁布实施,建设监理制在我国奠定了坚实的法律基础,监理的法律责任己得到明确。对此本文就监理工程师责任风险的合理规避,结合监理工程师的工作特点和风险种类进行分析,并提出相关的见解,希望对于监理工程师的有效发展起到促进的作用。
基础工程建设的岩土工程水文地质参数测定及其评价
Authors: 李 修民
Published: December 2018

基于岩土工程水文地质勘察在基础工程建设中的重要性,为提高岩土工程勘察质量,基础工程建设中的岩土工程地质勘察应查明与岩土有关的水文地质问题,评价地下水对工程建设可能产生的作用及其影响,基于此,本文阐述了水文地质的影响因素以及岩土工程水理性质与地下水变化的危害性,对基础工程建设中的岩土工程水文地质参数测定与评价进行了探讨分析,旨在保障基础工程建设的顺利实施。
建筑工程绿色施工技术应用解析
Authors: 劳 智宏
Published: December 2018

资源节约型、环境友好型社会是我国社会主义初级阶段始终坚定的发展目标,建筑行业作为高耗能产业,应认识到自身在实现绿色可持续发展上任重而道远。因此,文章通过对绿色施工技术的透彻分析,探究建筑工程施工过程中绿色施工技术合理应用的策略,从而实现改善建筑行业发展现状的目标,增强其发展的生态效益,与生态环境、自然环境构建平衡、和谐的发展关系。
简析配网系统中的电力设备运行及其维护
Authors: 王 顿
Published: December 2018

随着社会经济的快速发展以及工业化程度的提高,使得用电需求不断增加,同时对配网系统中的电力设备的要求也日显重要,为了充分发挥配网系统中的电力设备的作用,本文阐述了配网系统中的电力设备运行维护作用,对配网系统中的主要电力设备运行及其维护进行了简要分析。
建筑工程混凝土裂缝原因分析
Authors: 杨 艳红 , 李 大明 , 王 杰
Published: December 2018

在建筑工程的混凝土结构施工中,需要重点加强对混凝土裂缝的处理,并结合实际情况对裂缝产生的原因进行细致分析,从而采取合理的措施进行优化控制。文章就将对建筑工程混凝土裂缝原因及其防治措施进行相应阐述,以供借鉴。
建筑工程检测的必要性与检测要点
Authors: 闫 彬彬
Published: December 2018

建筑行业作为我国国民经济的支柱性产业，对拉动社会经济增长与实现社会经济持续发展都有着重要的影响，近年来随着建筑行业突飞猛进的发展，其对社会经济的影响力越来越大，为了实现经济的稳定、健康发展，促进建筑行业高质量、高效率的发展成为当前行业发展的主要任务，因而凸显了建筑工程检测的重要作用，其通过专业性的检测及时排查工程建设中存在的安全隐患与质量隐患，充分实现建筑工程的效益。为此，文章对建筑工程检测的必要性与检测要点进行了具体的探究。
大学生创业管理与大学生创业素质教育
Authors: 梅 燕飞
Published: December 2018

大学生作为我国的年轻高级知识人群有着较为丰富的知识储备和相较于其他高级知识份子所欠缺的创造力,是符合在我国十三五规划的创业主要人群。但因为大学生这个群体社会实践经验与能力的欠缺,与创业的成功要素所矛盾,导致大部分大学生创业在初期就自行夭折,使大学生创业成为了国家社会共同关注的话题。在十三五规划中,也针对这个现象有着相应的论述,给大学生创业这个创业过程带来了众多的机遇与挑战,大学生创业也将在这些机遇和挑战中走向新的高度。
大学生新媒体素养教育探究
Authors: 孙 靖瑜
Published: December 2018

21世纪是新媒体时代,以网络为依托的新媒体给全世界带来了非同寻常的机遇。新媒体以其数字化、多媒体、实时性和交互性传递新闻信息的独特优势而成为高校教育信息资源最为丰富和相互交流最为便捷的媒介,极大地影响着高校学生的思想、学习和生活。新媒体传播信息的海量对于大学生的接受能力是一种考验,在精力有限的条件下,信息数量的增加必然导致单条信息接收时间的缩减,大学生在这种情况下容易缺乏思考,盲目接收和传播某些信息。而对于高校的大学生来说,良好的新媒体素养的形成也必将对其以后的工作和学习带来积极、正面的作用和影响,使其成为媒介化社会的主力军。
电源开关的项目教学的探讨
Authors: 缪 汉文
Published: December 2018

开关电源技术课程是电气工程专业主干核心课程,这门课综合运用了前期所学的模拟电子技术、自动控制原理、电力电子技术、电磁场及仿真技术等课程知识,进行开关电源电路和系统设计的课程,是电气专业一门重要的专业实践课。这门课的实践性非常强,同时也是一门可以综合提高学生实践动手能力的课程。电子技术教学中,我们有的教师对开关电源部分内容常常忽视,这与目前生产、生活实际是不符,本文就电源开关的项目教学进行浅要分析。
大数据时代高职统计学教学改革问题分析
Authors: 何 庆
Published: December 2018

随着科技的卓越发展,大数据已逐步渗透到工业生产与日常生活的多个领域,并在潜移默化间改变了人们的思维模式和行为习惯。在大数据时代背景下,高职院校在开展统计学教育教学的过程中,要秉承与时俱进的基本原则,实现教学体制的深化变革,为社会输送高素质的全面型技术人才。
新时代、新思维、开启改革新征程
Authors: 丁 美娟 , 朱 伟琴
Published: December 2018

改革开放40年我国取得了令世人瞩目的辉煌成就：中国人民的生活实现了由贫穷到温饱,再到整体小康的跨越式转变；中国社会实现了由封闭、贫穷、落后和缺乏生机到开放、富强、文明和充满活力的历史巨变；中国经济实现了持续快速增长,GDP从78年的3700亿元增长到了2017年的82.7万亿元,经济总量稳居世界第二,对世界经济增长贡献率超过30%,居世界第一,中国已是世界第一工业大国、第一服务业大国、第一贸易大国。本文就改革开放40周年取得巨大成就的经验及如何开启改革新征程谈点粗浅的看法。
如何在企业中持续推进“两学一做”学习教育常态化制度化
Authors: 王 媛
Published: December 2018

推进“两学一做”学习教育常态化制度化，着重在抓住关键少数、抓实基层支部上持续用力，以“两学一做”为基本内容，以“三会一课”为基本制度，以党支部为基本单位，以解决问题、发挥作用为基本目标，融入日常、抓在经常、形成长效。党员领导干部要带头学、带头做，把学党章党规、学系列讲话作为主要内容，不断提升和改造自己，践行“四讲四有”做合格党员。
体验式教学在中职音乐教育中的应用初探
Authors: 黄 东妮
Published: December 2018

中职音乐教育对提升学生的艺术修养和综合素质有着十分重要的作用，在中职音乐教学中应积极应用体验式教学模式，从而使学生能够掌握更多的知识和技能，不断增强学生的音乐鉴赏能力。本文就主要分析了体验式教学在中职音乐教育中的应用，以供参考。
“What can I offer America?” A postcolonial analysis of faculty motivations and perceptions in North-South university partnerships
Authors: Mlambo Yeukai Angela , Baxter Aryn
Published: December 2018

International university partnerships are a prevalent internationalization strategy for both North American and African higher education institutions, yet the predominance of discourses that reflect the inequities of the global knowledge economy among participants perpetuate the very challenges that they are designed to address. Using a postcolonial framework, this study provides a critical analysis of qualitative interviews conducted with faculty members from one West African and one U.S. university participating in an international higher education partnership. The paper examines the motivations and perceived benefits of the partnership among participants at both institutions. It argues that the history of inequitable relationships perpetuated by globalization continues to shape understandings and pose challenges to achieving mutuality in North-South university partnerships. Findings show, for both institutions, motivations for partnership participation are based on the expectations and anticipated benefits to their institution as well as an alignment with the individual’s personal goals and objectives. Furthermore, perceptions of power imbalances between participants at the two institutions are evident. Despite the partnership’s intent for mutuality and reciprocity, the narratives of both West African and U.S. participants reinforce inequitable hierarchies. However, they also highlight opportunities for working toward greater mutuality and intercultural learning through North-South partnerships. Recommendations for cultivating reciprocity in North-South university partnerships are provided.
Producing Relevant Medical Education Through Community-Engaged Scholarship
Authors: Nkhoma Nelson Masanche
Published: December 2018

AbstractSome African higher education institutions (HEI