bluuebunny/crossref_metadata_2025 huggingface dataset:
Physiological fluid systems modelling and visualization
Authors: Čápová Klára , Blazek Vladimír , Čáp Ivo , Bučkuliaková Lýdia
Published: December 2018

The paper deals with the modelling and the simulation of physiological fluid systems with the emphasis on the human vascular system. The presented simulation method has been developed as a helpful tool for the computer-aided non-invasive diagnostics of living bodies. Using the electromechanical analogy between physiological and electrical values the introduced method makes possible the description and 3D representation of the non-linear characteristics of the human haemodynamics as well. The simulation procedure and the obtained results verified by the experiment enable to visualize all physiological and pathophysiological states of the human vascular system.
Effect of pulse parameters on visual nervous system
Authors: Kanda Hiroyuki , Watanabe Masami , Fujikado Takashi , Yagi Tohru
Published: December 2018

In a visual prosthesis, the visual nervous system of blind people are stimulated electrically in order to reconstruct their sense of sight. However electrical power supply to an internal device is limited. Therefore, it is very important to study efficient electrical stimulation. In our study, various pulse types were applied to the lateral geniculate nucleus (LGN) to record the neural responses from the visual cortex (V1) of cats. Experimental results revealed that the inversion of polarity of electric current pulse was effective in electrical stimulation to the LGN.
Visualization of back surface defects by piezoelectric film
Authors: Komagome Yuji , Matsumoto Eiji
Published: December 2018

The surface strain distribution of a plate can be measured from the electric potential on the piezoelectric film mounted on it. When the plate with a back surface defect is deformed, the resultant strain distribution on the front surface reflects the size and the shape of the defect. Instead of measuring the electric potential by the electrostatic voltmeter, this paper attempts to visualize the strain distribution by means of absorption of charged polymer powder to the piezoelectric film. And also attempting this method to the various size of the defect, resolution of detecting the defects is discussed by the experiment.
Magnetostriction and magnetic characteristics of giant magnetostrictive thin film
Authors: Wakiwaka Hiroyuki , Yamada Yoji , Watanabe Toshihiko , Umemoto Yoshiyuki , Kiyomiya Teruo , Makimura Mika
Published: December 2018

Giant magnetostrictive thin films are suitable to develop new micro-sensors and micro-actuators due to their superior characteristics. In this paper, the influence on magnetostriction characteristic of magnetron sputtered film by sputtering condition is described. The thin film shows large magnetostriction in Tb composition 40 at %, in anneal temperature 300°C.
On the modeling of 3-D inclusions in conductive media using extended Born models in the diffusive regime
Authors: Reis D. Dos , Lambert M. , Lesselier D.
Published: December 2018

Diffusive fields in 3-D configurations, e.g., as those faced when searching for inclusions in conductive planar layered media (a metal slab, a half-space subsoil) at low frequencies, can be modeled via Green's integral formulations that require Green dyads. Such formulations make good use of extended Born approximations in order to express the secondary sources existing within the probed inclusion from the primary fields at same location. Here it is sketched how several such approximations perform in cases of interest by comparison with full solutions and benchmark measurements.
Simulation of amplitude and phase characteristics during inspection of printed circuit board by eddy-current testing probe
Authors: Kacprzak Dariusz , Yamada Sotoshi , Iwahara Masayoshi
Published: December 2018

This paper presents simulated amplitude and phase characteristics obtained during the inspection of printed circuit board by an eddy-current testing probe. The simulation is based on the ``two-components'' nature of the output signal. Amplitude and phase characteristics, obtained during the experimental inspection and simulation, are presented.
Development of ID-blade slicer monitoring system for cutting 12-inch silicon ingot
Authors: Jiang Zhongwei , Fujiwara Shusuke , Chonan Seiji , Kawashima Kazuo
Published: December 2018

This work is concerned with an experimental study on online measurement of the states of ID saw blade cutting a 12-inch crystal ingot. An online monitoring system consisting of a 3-axis piezoelectric sensor, a three-band digital filter, a digital oscilloscope and computer was developed. Since the acoustical and chatter vibration signals during cutting ingot were complex, they are decomposed in three frequency regions to evaluate the blade extension circumstance, the sharpness of blade edge and the interference between blade and ingot. The proposed ID-Blade slicer monitoring system is validated for evaluation of the blade slicing 12-inch silicon ingots.
Design parameters characteristics of X-Y linear synchronous motor without detent force
Authors: Fujii Nobuo , Tanaka Shinobu , Okinaga Kinjiro
Published: December 2018

As a two-dimensional movement motor, the double-sided X-Y linear synchronous motor without armature core has been proposed as a precise positioning device. The linkage flux density and thrust are studied analytically by using three-dimensional numerical analysis. The results show that this motor has sufficiently large values on them and the satisfied thrust per mass in the air core type for the double-sided pole configuration. There is little ripple in the thrust in the motion to any position as there is no detent force.
On some linear and angular displacement electromagnetic sensors
Authors: Lozovan M. , Cosma V.M. , Rochat Monica Cosma , Mihalache O. , Chiriac H.
Published: December 2018

We present in this paper a displacement-frequency sensor including a non-linear resistor with a dynatron-type i(v) dependence, a variable coil and a d.c. voltage source. A general relation is given for the dependence of the period of the oscillations on the coil inductance and on the negative variable resistance of the non-linear resistor respectively. The functioning data of the sensor are presented, for linear and angular displacement respectively. Our sensors could find interesting applications in cardiology.
Sensitivity for a synchronous generator
Authors: Hantila F. , Vasiliu M. , Preda G. , Demeter E.
Published: December 2018

The paper presents a very useful method for computation of the sensitivities of electrical machines, taking into account the non-linearity of the ferromagnetic bodies. In the first step, the magnetic field in non-linear media and the performances of the given machine are calculated. The non-linear medium is replaced with a linear medium having a magnetic polarization that is iteratively corrected by the flux density. Each linear field problem is solved using the periodic Green function. In the second step, the difference of the magnetic field due to the small modification is computed directly. The polarization of the eliminated ferromagnetic domain is the field source. The{\bf B-I} relation is given by Frechet first derivative.
Optimal design of permanent magnet brushless AC machines for electric vehicle applications
Authors: Schofield N. , Giraud-Audine C. , Powell D.J. , Howe D.
Published: December 2018

Permanent magnet brushless ac machines are ideally suited for traction applications, since they are energy efficient and have a high specific torque and a high peak to continuous torque capability. Further, they can be field-weakened to facilitate constant power operation over an extended speed range without compromising the VA rating of the drive. However, they must be design optimised with due regard to their duty cycle, their thermal management, the volt-ampere constraint of the drive and any space envelope constraints. A design methodology which accommodates these aspects into the electromagnetic design synthesis process has been developed and employed to design a traction machine for a small urban vehicle.
Examination of the method for analyzing inverse problem to determine the internal current of bulk high-Tc superconductor
Authors: Ochiai Hiroyasu , Torii Susumu
Published: December 2018

This paper reports about the validity of the numerical model for presuming the internal current of the superconductor that is difficult to measure. The validity of the numerical method is confirmed by the simple analysis model. This model is constituted applying boundary element method and the difficulty of measuring the internal current is solved by the inverse problem from the exterior flux density distribution. Since the application of this model draws the solution of an irreversible magnetization phenomenon not clarified, the apparatus that uses the superconductor will develop.
Feature extraction techniques for ultrasonic signal classification
Authors: Simone G. , Morabito F.C. , Polikar R. , Ramuhalli P. , Udpa L. , Udpa S.
Published: December 2018

In this paper, we present two feature extraction techniques for the classification of ultrasonic NDE signals acquired from weld inspection regions of boiling water reactor piping of nuclear power plants. The classification system consists of a pre-processing block that extracts features from the incoming patterns, and of an artificial neural network that assigns the computed features to a particular class of defect present on the inspected pipe. The two techniques are respectively based on the discrete Gabor transform(DGT) and on the discrete wavelet transform (DWT); a third feature extraction technique, based on the clustering of the wavelet coefficients, is also presented. The results carried out by artificial neural networks trained and tested using the described feature extraction techniques, demonstrate the usefulness of the clustered DWT method with respect to the well known techniques of DGT and DWT.
Magnetic fracture mechanics of ferromagnetic plates
Authors: Shindo Yasuhide , Horiguchi Katsumi
Published: December 2018

The bending of through-cracked ferromagnetic plates in a static magnetic field is investigated to show the effect of induced magnetization. A simple experimental technique employing strain gages is used to determine the magnetic moment intensity factor. The theoretical results agree very well with the experimental data. The scattering of time harmonic flexural waves by a through crack in an infinite plate under a uniform magnetic field is also studied.
B-H curve reconstruction from MFL signals based on genetic algorithms
Authors: Cranganu-Cretu Bogdan , Preda Gabriel , Mihalache Ovidiu , Chen Zhenmao , Miya Kenzo
Published: December 2018

B-H curve reconstruction starting from magnetic flux leakage (MFL) signals measured outside the tested specimen is attempted. Non-linear constitutive relation is modeled by means of three parameters, suitable for describing low fields magnetization curve. A FEM-BEM approach is used to solve the forward problem whilst the inverse problem is tackled with a genetic algorithm application. Results of the reconstruction are presented.
Non-destructive detection of damage in an austenitic stainless steel SUS 304 by the use of martensitic transformation
Authors: Nakasone Yuji , Iwasaki Yoshifumi , Shimizu Tetsu
Published: December 2018

The present study investigates a method for the non-destructive detection of damage in an austenitic stainless steel SUS 304 by the use of martensitic transformation. Volume fraction of α' martensite transformed in uniformly stretched SUS304 plates was measured and expressed as a function of the applied strain levelε. The distributions of α' phase in the plastic wake regions produced around fatigue cracks were then electromagnetically measured in fatigued SUS 304 plate specimens. The results were compared with the distributions of magnetic flux density B_{z} above the fatigue cracks in the specimens magnetized by a strong magnetic field higher than 0.4 T. It was revealed that the B_{z} distributions reflected the α" phase distributions in the wake regions: i.e., the distance between the points where B_{z} reached the minimum and the maximum had a high correlation with the fatigue crack length, and the minimum and the maximum values of B_{z} showed a linear relationship with the applied stress intensity factor range ΔK. These results imply that not only the crack length but also the fatigue damage can be detected effectively in an electromagnetic non-destructive way.
Smart visualization of multi-scale turbulent structures
Authors: Li Hui , Zhou Yu , Takei Masahiro , Saito Yoshifuru , Horii Kiyoshi
Published: December 2018

The vector wavelet multi-resolution technique based on the orthogonal wavelet transform was used to analyze the velocity vector data that were simultaneously obtained by sixteen X-wires in the turbulent near-wake of a circular cylinder at different streamwise positions. The instantaneous velocity vector field is decomposed into the multi-scale structures, and its sectional streamline of various scales is displayed. The large-scale structures in the plane of mean shear are consistent with the well-known Kármán vortices. The structures that correspond to the saddle region between Kármán vortices are identified with the rib-like structures. Even smaller scale structures are also observed. As increasing x/d, the decay of vortical structure and rib-like structure are observed. The topologies of Reynolds stress and RMS vorticity associated with the multi-scale structures are discussed at different downstream positions. It is found that the most significant contribution to Reynolds stress comes from the frequency components of f ≤ 219 Hz at x/d = 20. However, the contribution to Reynolds stress coming from the intermediate-scale structure becomes weak at x/d = 40. The RMS vorticity components of f = 875 Hz is the largest among all components.
Magnetic circuit analysis based on the finite elements
Authors: Yabunami H. , Hayano S. , Saito Y.
Published: December 2018

As is well known, conventional magnetic circuit theory makes it possible to analyze the three-dimensional magnetic fields, even though its theoretical background is based on the engineering experiences. On the other side, finite elements have a firm theoretical background but it is too expensive to implement the three-dimensional analysis. In order to carry out the three-dimensional magnetic field analysis in a most efficient manner, we propose the theory of modern magnet circuit based on finite elements. This makes it possible to implement the three-dimensional magnetic field computation in a quite efficient manner. A simple example demonstrates not only the usefulness but also efficiency of our new methodology.
A new interpolation method for interactive visualization system
Authors: Noguchi So , Yamashita Hideo , Matsubayashi Yutaka , Okayama Eiji
Published: December 2018

A new interactive visualization system for education and design purposes in 2D electromagnetics is proposed. The proposed system using numerically computational results for several typical model configurations can display interactively electromagnetic field phenomena for any other model configuration bounded with the previously computed ones. It uses simple bilinear interpolation techniques in order to provide fast interactive display. This visualization system can be used for design purposes of problems with different model configurations and as an educational tool for teaching electromagnetics.
Image reconstruction for electromagnetic field visualization by an inverse problem solution
Authors: Marinova Iliana , Endo Hisashi , Hayano Seiji , Saito Yoshifuru
Published: December 2018

The purpose of this article is to apply an inverse approach for image reconstruction during electromagnetic field visualization. The reconstruction of the images is formulated as an inverse problem. For the image color model, the Poisson equation with open boundary condition is imposed. The color source densities have been evaluated from the color distributions for electromagnetic field data set. The Generalized Vector Sampled Pattern Matching method is applied to solve an ill posed linear system of equations for the corresponding inverse problem. The new color distributions are generated and visualized using the obtained color source densities. With the proposed inverse approach the dark parts of the images can be reduced or completely removed. This article collects several examples for electromagnetic field visualization of the most commonly used sensor coil.
Optimal piezo-electro-mechanical coupling to control plate vibrations
Authors: Alessandroni Silvio , dell'Isola Francesco , Frezza Fabrizio
Published: December 2018

A new way of coupling electrical and mechanical waves, using piezoelectric effect, is presented here. Since the energy exchange between two systems supporting wave propagation is maximum when their evolution is governed by similar equations, hence, an optimal electro-mechanical coupling is obtained by designing an electric network which is "analog" to the mechanical structure to be controlled. In this paper, we exploit this idea to enhance the coupling, between a Kirchhoff-Love plate and one possible synthesis of its circuital analog, as obtained by means of a set of piezoelectric actuators uniformly distributed upon the plate. It is shown how this approach allows for an optimal energy exchange between the mechanic and the electric forms independent of the modal evolution of the structure. Moreover, we show how an efficient electric dissipation of the mechanical energy can be obtained adding dissipative elements in the electric network.
Depressurization behavior of vacuum vessel pressure suppression systems in fusion reactors at multiple first wall pipe break events
Authors: Takase K. , Akimoto H.
Published: December 2018

An integrated ICE (Ingress-of-Coolant Event) test facility was constructed to demonstrate that the ITER (International Thermonuclear Experimental Reactor) safety design approach and design parameters for the ICE are adequate. Major objectives of the integrated ICE test facility are to estimate the performance of an integrated pressure suppression system and obtain the validation data for safety analysis codes and clarify the two-phase flow behavior under vacuum. The integrated ICE test facility simulates the ITER components with a scaling factor of 1/1600. The modified TRAC-PF1 code is used to verify the integrated ICE experimental results. From the present study the effectiveness of the ITER pressure suppression system was verified experimentally and analytically, and then, it was clarified quantitatively that the prediction accuracy of the modified TRAC-PF1 code is very high.
Evaluation on fracture toughness of low activation ferritic steel(JLF-1)
Authors: Yoon H.K. , Lee S.P. , Seok C.S. , Kohyama A.
Published: December 2018

Low activation ferritic steels have been developed for a candidate of structural materials in nuclear fusion reactor applications. This paper dealt with the effects of rolling direction and side groove on the fracture toughness of low activation ferritic steel, JLF-1 Steel (9Cr-2W-V-Ta). The fracture toughness of JLF-1 steel showed the anisotropy in the rolling direction. In the case of J-R curve, J_{Q} and slope of the longitudinal JLF-1 steel (BML) for the rolling direction were a slight larger than those of transverse JLF-1 Steel(BMT) at room temperature. In order to obtain the valid fracture toughness of JLF-1 Steel through the UC method, the CT specimen with a side groove of 40% was recommended.
Duration tests of an experimental high temperature superconducting fault current limiter
Authors: Vajda I. , Györe A. , Porjesz T. , Sokolovsky V. , Meerovich V.
Published: December 2018

The concept of an all-superconducting (AS) mini power plant (MPP) model is presented. An experimental HTS fault current limiter (FCL) for the protection of the generator unit of the AS MPP model was designed. During its lifetime the HTS FCL can be activated thousands of times. Duration tests were performed on the HTS FCL to determine the dependence of the value of the limited current and the voltage of the FCL on the number of activations of the device. The experiments have shown that the parameters of the HTS FCL are approximately constant after three thousand activations. This result indicates that the relevant parameters of the HTS ring used in the device are approximately constant, and that the FCL can be designed and used in the network with predictable parameters.
Performance study of high current photo-cathode RF-gun with new laser system
Authors: Kobayashi T. , Muroya Y. , Watanabe T. , Ueda T. , Yoshii K. , Uesaka M. , Katsumura Y. , Nakajima K. , Zhu X.
Published: December 2018

For a sub-picosecond pump-and-probe-type radiation chemistry work, a new synchronized electron linac and laser system was installed in Nuclear Engineering Research Laboratory (NERL) of University of Tokyo. The new 0.3 TW laser system with a Ti:Sapphire oscillator (795 nm) and amplifiers generate 300 ps pulses at 10 Hz at first. The laser is splitted into the two beams. The first is compressed to 4 ∼ 11 ps so as to drive the RF-Gun and generate a pump-electron-beam. The second is compressed to 100 fs and used for the probe-light. The drive laser is converted to the third harmonics(265 nm, < 250 μJ). Moreover, a new 15 MW klystron was installed for the linac RF system. The RF power is divided to the gun and the accelerating section. Finally the time jitter between the pump-electron-beam and the probe-laser is designed to be 320 fs (rms). By using the new drive laser system, the charge of 7 nC per bunch was observed at the exit of the gun. Improvement of the vacuum in the gun < 10^{-9} Torr) is most effective to obtain such a high charge beam. After two and a half years operation of the gun, no degradation of QE has been found for the Cu photo-cathode.
A study on conductive polymer electrodes for stimulating the nervous system
Authors: Ito Yuichiro , Yagi Tohru , Ohnishi Yasushi , Kiuchi Kazutoshi , Uchikawa Yoshiki
Published: December 2018

The purpose of this study is to develop an implantable micro-electrode array, which is made of the conductive polymer, polypyrrole(PPy). For that purpose, we tried to fabricate micro-patterns of PPy using the photochemical reaction of oxidative polymerization agents. Moreover, the conductivity of the micro-pattern was evaluated in terms of pattern width, length and polymerization time. Experimental results showed that we could fabricate the micro-patterns, which had a line width of 3 μm. This size was small enough for the purpose mentioned above. In addition, the conductivities of the micro-patterns were proportional to their width and length, and could be improved by suitable polymerization time. These results showed that the micro-patterns seemed to be applicable to a neural stimulating electrode.
Mathematical model of a magnetoresistive transducer for eddy current nondestructive testing of materials
Authors: Sikora Ryszard , Komorowski Mieczysław , Gratkowski Stanisław , Enokizono Masato , Chady Tomasz
Published: December 2018

The paper presents a simplified mathematical model of a magnetoresistive transducer, which is used for eddy current non-destructive testing of conducting materials.
Electromagnetic-thermal analysis of a hybrid switched-reluctance motor
Authors: Rizzo M.
Published: December 2018

The density distribution of the magnetic field and the overheating distribution were simultaneously submitted to a coupled analysis by the Finite Element Method. A 2-D model was adopted for the magnetic field as well as for the thermal field.
Multi-speed polyphase induction motors
Authors: Kluszczyński Krzysztof
Published: December 2018

It is explained why a polyphase (m > 3) induction motor supplied separately by single consecutive symmetrical components of voltage behaves as a multi-speed motor. As an example a 9-phase 4-speed motor is considered and results of computer simulations are presented. As regards the theory of polyphase machines it is shown that the so-called diagram of decomposition of polyphase induction motor into elementary machines (the graphical representation of a motor model in αβ 0 coordinates) is very convenient means for their analysis and modelling.
Electromagnetic and micro-magnetic non-destructive characterization (NDC) for material mechanical property determination and prediction in steel industry and in lifetime extension strategies of NPP steel components
Authors: Dobmann Gerd , Altpeter Iris , Becker Rainer , Lang Marco , Kern Rolf , Yashan Andrij , Theiner Werner
Published: December 2018

Nondestructive characterization (NDC) of materials is a technology of increasing application by industrial users for process monitoring and control as well as in predictive maintenance procedures integrated in plant lifetime management systems. The main reason for this fact in materials processing is the need for a better process understanding and mastering in order to produce quality according to a zero-defect-principle and the objective to reduce non-conformities compared with a given quality specification. This means: Integration of NDC by use of intelligent sensors into monitoring and control systems to predict mechanic properties and to detect and document their discontinuities. For lifetime management of components in plants NDC is asked for to support lifetime prediction procedures, which have to be observed if lifetime extension is an objective to reduce costs.
Numerical analysis of eddy current testing for tubes using uniform eddy current distribution
Authors: Hashimoto Mitsuo , Kosaka Daigo , Ooshima Kenichi , Nagata Yasutaka
Published: December 2018

The eddy current testing is used for a testing of the steam generator tubes in pressurized water reactor nuclear power plants because of its high accuracy and high speed. It is important to judge shape of cracks from measured signals. We have developed a rotating type probe using an excitation coil that generates uniform eddy current distribution. Because the shape of excitation current source has no influence on detecting cracks, numerical analyses for this probe are handled simply by devising boundary condition. Aid of numerical analyses has enhanced the evaluation of complicated cracks.
Numerical techniques in finite element analysis of eddy current testing problem
Authors: Tanaka Motoo , Tsuboi Hajeme
Published: December 2018

Several types of finite element methods have been developed and shown the validity and the effectiveness for eddy current testing (ECT) problem. However, it is difficult to analyze the finite element model including two or more objects whose positions relatively change, such as conductor plate and ECT probe. Furthermore, it takes a large amount of computer resources to compute an accurate finite element model for a natural crack, because of the complex shapes and the narrow gap. In this paper, a superposition method to avoid the finite element mesh regeneration for the relative position change is presented, and the method is applied to the ECT probe with a ferrite core. Furthermore, the finite element model for the natural crack is shown and the model is applied to the ECT problem with the fatigue crack.
Development of novel NDE techniques and their significance in the COE program on the physics and chemistry of fracture and failure prevention
Authors: Shoji Tetsuo , Sato Yasumoto , Minkov Dorian , Yagi Kenichi , Baba Toshimitsu , Tamakawa Kinji
Published: December 2018

The objective of the Center of Excellence (COE) program is to provide a fundamental understanding of the physics and chemistry of fracture under combined environments and to apply this understanding to establish structural life prediction and control systems for high quality human safety. With this aim, we have developed analytical methods for the local measurement of materials chemistry, crack tip water chemistry, crack tip strain and defects. We summarize the research activity of COE program and some recent progress using the electromagnetic NDE technique will be reviewed.
Generalized transmission-line theory for the treatment of nonuniform multiconductor transmission lines
Authors: Haase Heiko , Nitsch Jürgen
Published: December 2018

This paper presents a generalized transmission-line theory which is useful to describe the wave propagation along almost arbitrary three-dimensional wire structures. In contrast to the classical transmission-line theory this new approach is an approximate full-wave description based on generalized telegrapher's equations. Whereas the mathematical structure of the classical telegrapher's equations is preserved, the coefficients (the per-unit-length parameters) are generalized in order to represent the intrinsic behavior of the wire structure. MoM simulations were performed to validate the predicted data.
A practical approach for the design of multivariable control systems
Authors: Hofer Anton , Horn Martin
Published: December 2018

In this paper the design of linear multivariable control systems based on the l_{1} - system norm is revised. It is shown how the well known computational difficulties inherent in this design problem can be overcome. For this purpose a procedure is proposed consisting of the steps 1) design of a suitable low order controller by semidefinite programming, 2) parametrization of all stabilizing conrollers based on the controller of the first step, 3) solution of the design problem with linear programming methods. The efficiency of this method is demonstrated by an example.
Modeling of nonlinear electrical networks: A computeralgebra approach
Authors: Kugi Andreas , Schlacher Kurt , Grabner Herbert
Published: December 2018

In several applications a symbolic description of nonlinear electrical networks is of great importance. Thus, this paper is concerned with the systematic derivation of the mathematical models of a certain class of nonlinear electrical networks in view of an efficient computeralgebra implementation. The approach being proposed is based on a modified version of the famous equations of Brayton-Moser in combination with the so-called state-tree representation. The network algorithms are implemented in an object-oriented package in the computeralgebra program Maple and they have been tested for several nontrivial examples.
Matrix representations and parameterizations of lossless and reciprocal multiports
Authors: Loose Hannes , Pauli Rainer
Published: December 2018

Stimulated by recent work on the synthesis of a certain class of surface acoustic wave (SAW) filters, we discuss the exceedingly classical subject of physical realizability criteria for lossless, and reciprocal linear multiports. We give an essentially coordinate-free formulation of the realizability conditions for passive, lossless and reciprocal multiports. For this sake we describe a linear multiport by its external behavior (the linear subspace generated by all admissible signal pairs at the ports) and analyze the properties of this space in terms of Gramians of its bases with respect to physically relevant metrics. The standard matrix representations (impedance matrix, scattering matrix, …) arise by the introduction of various affine coordinates in the external behavior. Instead of discussing their well-known coordinate-dependent properties we focus on the so called P-matrix as an attractive non-standard example and study its properties and relations to other matrix representations. As a major result we show that the parameterization of lossless multiports as induced by the P-matrix is largely equivalent to the Arov-Dewilde-Dym parameterization of J-inner functions.
Mathematical foundations of the TC-method for computing multiple DC-operating points
Authors: Reibiger A. , Mathis W. , Nähring T. , Trajković Lj.
Published: December 2018

In this paper, we present a detailed mathematical analysis of nonlinear resistive networks with multiple dc-operating points. In our approach, we use elementary set theoretical principles of network theory. We propose two new approaches: the TC-method (transfer-characteristic method) and the DPC-method (driving-point characteristic method). We use the TC-method to reduce the computation of dc-operating points of a given nonlinear resistive network to the computation of crossing points between transfer characteristics of associated modified resistive networks with a straight line. It can be proved that at least one operating point of the given network corresponds to each such crossing point. We show that the proposed approaches lead to continuation methods for the finding dc-operating points of resistive networks. These continuation methods can be readily used in standard SPICE-like circuit simulators.
Remarks on accessibility and oberservability of nonlinear implicit systems
Authors: Schlacher Kurt , Kugi Andreas
Published: December 2018

This contribution presents tests, based on Lie-groups, for the accessibility and the observability of dynamic systems described by a set of implicit ordinary differential equations. It is shown that non-accessible or non-observable systems admit Lie-groups acting on their solutions such that distinguished parts of the system remain unchanged. The approach being presented requires the formal integrability of the system. Therefore, a short introduction to this theory is presented, as well as its application to systems of differential equations. Besides the theoretical results sketches for computer algebra based algorithms are presented that are necessary to perform the test for higher order systems.
A numerical optimisation method for obtaining technically smooth magnetisation characteristics
Authors: Vande Sande Hans , Pahner Uwe , De Gersem Herbert , Hameyer Kay , Froyen Ludo
Published: December 2018

In general, if measurements can be repeated several times assuming the same conditions, the measurement error can significantly be decreased by statistically evaluating the measurements. However, an uncertainty band always remains. Non-linear numerical simulations based on e.g. the Newton-Raphson method may establish a poor convergence if they are provided directly with measured data. Therefore, data pre-processing is required. Here, a neural network approach is employed. A two-layer perceptron is fitted on a measured magnetisation curve, thereby restricting the solution to be technically feasible while accepting the statistical nature of the data. By using a perceptron, an analytical expression of the magnetisation curve is obtained and expressions for its derivatives can easily be computed.
A piezoelectric gyroscope based on extensional vibrations of rods
Authors: Yang J.S. , Fang H.Y.
Published: December 2018

A piezoelectric gyroscope consisting of a concentrated mass connected to two orthogonal piezoelectric rods in extensional vibrations is proposed. A simple theoretical model is constructed for the proposed gyroscope, which allows complete analytical analysis. Simple close form solutions for free and forced vibrations are obtained. Resonant frequencies, output voltage and current as well as their dependence on various geometric and physical parameters are examined.
Image reconstruction of a two-dimensional periodic imperfect conductor by the genetic algorithm
Authors: Chiu Chien-Ching , Li Ching-Lieh , Ho Cheng-Shun
Published: December 2018

The image reconstruction of a two-dimensional periodic imperfect conductor by the genetic algorithm is investigated. A periodic imperfectly conducting cylinder of unknown periodic length, shape and conductivity scatters the incident wave in free space and the scattered field is recorded outside. Based on the boundary condition and the measured scattered field, a set of nonlinear integral equations is derived and the imaging problem is reformulated into an optimization one. The genetic algorithm is then employed to find the global extreme solution of the object function. As a result, the periodic length, the shape and the conductivity of the conductor can be de-embedded. Numerical results demonstrate that even in the presence of noise, good reconstruction can be obtained.
Evaluation of abnormal respiratory sound "crackle" using time-expanded waveform and FFT analysis
Authors: Kawamura Takeo , Matsumoto Tsuneo , Miura Gouji , Matsunaga Naofumi , Kido Shoji , Jiang Zhongwei
Published: December 2018

Purpose: Many diseases such as bronchial asthma or pneumonia are detected by chest auscultation with a stethoscope. However, there are no obvious criteria for evaluating the chest auscultation findings. In the present study, chest auscultation findings were evaluated by digital computer analysis.

Material and method: "Crackle" was evaluated among abnormal respiratory sounds. Crackles with very short duration were extracted from recorded respiratory sounds, and FFT (Fast Fourier Transform) analysis was used.

Result: Spike-like waves could be recognized visually in the time-amplitude plot of respiratory sounds. The durations of each crackle ranged between 12.6 and 31.3 msec. The high/low-pitched sound ratio calculated by FFT analysis ranged between 0.059 and 3.24.

Conclusion: The characteristics of crackles could be evaluated objectively by computer analysis. The high/low-pitched sound ratio correlated with the computed tomography (CT) findings and the ratio is useful for differential diagnosis of the disease.
Distributed flexible tactile sensor system
Authors: Yu Kee-Ho , Yoon Myoung-Jong , Kwon Tae-Kyu , Lee Seong-Cheol
Published: December 2018

This paper represents the development of a distributed flexible tactile sensor using PVDF (polyvinylidene fluoride) film. The tactile sensor which has 8 × 8 tactile elements is fabricated using PVDF film and flexible circuitry. Experimental results on static and dynamic characteristics are obtained. In order to investigate the characteristics of the tactile sensor, the output of the tactile sensor is measured by applying arbitrary forces and frequencies those are excited to the shaker. In the static characteristics the threshold and the linearity of the sensor are investigated. Also the dynamic response of the sensor subjected to the variable frequencies is examined. The signals of a contact pressure to the tactile sensor are sensed and processed in the DSP system in which the signals are digitalized and filtered. Finally, the signals are integrated for taking the force profile. The processed signals of the outputs of the sensor are visualized in personal computer, the shape and force distribution of the contact object are obtained using two and three-dimensional image in real time. The reasonable performance for the detection of contact state is verified through the experiment.
LonWorks-based Virtual Device Network (VDN) for predictive maintenance
Authors: Song Ki Won , Choi Gi Sang , Choi Gi Heung , Kim Jung Soo
Published: December 2018

Requirements for Distributed Monitoring and Control Networks (DMCN) differ greatly from those of typical data networks. Specifically, any DMCN technology which employs a fieldbus protocol is different from IP network protocol TCP/IP. In general, one needs to integrate fieldbus protocol and TCP/IP to realize DMCN over IP network or internet, which can be viewed as Virtual Device Network (VDN). Interoperability between devices and equipments is essential to enhance the quality and the performance of predictive maintenance (PM). This paper suggests a basic framework for VDN using DMCN over IP network and a method to guarantee interoperability between devices and equipments.
Robust control of a quad-rotor aerial vehicle
Authors: Suh Young Soo
Published: December 2018

This paper is concerned with robust control of a quad-rotor aerial vehicle attitudes (pitch, roll, yaw). Attitudes of the quad-rotor vehicle is affected by various sources of disturbances such as wind and ground effect. In this paper, we propose a new disturbance observer so that these disturbances are estimated and compensated by the disturbance observer. It is shown by simulations that the proposed disturbance observer effectively compensates disturbances.
Control of transport structures in a rotating liquid cylinder by means of an applied magnetic field
Authors: Okano Y. , Kondo H. , Dost S.
Published: December 2018

Transport structures such as the convective flow and temperature field patterns in a rotating metallic liquid cylinder under a static magnetic field was numerically simulated. It was found that crucible rotation suppresses the natural convection in the vertical plane while it gives rise to uniform mixing in the horizontal plane. The natural convection in the liquid is enhanced at lower magnetic field levels while it is suppressed significantly at higher magnetic field levels. It also observed that the contribution of crucible rotation is diminished at higher magnetic field levels. Temperature distributions are not affected significantly by crucible rotation. The conclusion is that the combined effects of an applied magnetic field and a crucible rotation can be utilized to minimize undesirable radial segregations in grown crystals and obtain flatter melt/crystal interfaces in the melt crystal growth techniques such as the Vertical Gradient Freezing and Vertical Bridgman.
Marangoni convection in a hemispheric molten silicon droplet and its control by an applied magnetic field
Authors: Okano Yasunori , Sakai Susumu , Yamada Hiroshi , Hoshikawa Keigo , Dost Sadik
Published: December 2018

A numerical simulation study was conducted for the "sessile drop method" that is one of the essential tools for conducting measurements of physical properties in droplets. The effect of the Marangoni convection on the maximum flow velocity in a hemispheric molten silicon droplet was examined. The maximum Reynolds number was correlated with the Marangoni and Biot numbers, and the surrounding temperature by Re_{max}= [-209.4{T_a(π/2)/T_{mp}} + 216.8] … (BiMa)(when BiMa < 40) and Re_{max} = [-472.5{T_a(π/2)/T_{mp}} + 491.3] …(BiMa) ^{2/3} (when BiMa > 40). Simulation results show that the application of a vertical magnetic field can suppress the flow in the droplet near the plate, and consequently prevent the movement of the drop, and give rise to a diffusion-limited-condition near the plate where accurate measurements of the physical properties of a melt can be made.
Solutions for curvilinear cracks in bonded dissimilar materials subject to uniform magnetic induction
Authors: Lin Hsien-Mou , Lin Chun-Bo , Chen Shin-Cheng
Published: December 2018

The magnetoelastic problem of curvilinear cracks lying along the interface between two dissimilar ferromagnetic materials under remote uniform magnetic induction is considered. On the basis of the Hilbert formulation and a special technique of analytical continuation, the solutions of the magnetic and the magnetoelastic stress fields either in the matrix or in the inclusion are expressed in a general form. Just like the pure elastic problem of curved cracks or the magnetoelastic problem of straight cracks in bonded dissimilar media, the trig-log character for the singularity of magnetoelastic stresses is found in this paper. Both the explicit solutions and the numerical results for the illustrating case of a single circular-arc crack in bi-material plate with typical ferromagnetic materials are given to elucidate the use of the present study. It is noted that the stress intensity factors are obtained and verified by comparison with the existing ones under special cases. The validity of the crack opening condition is also discussed.
A new magnetic NDE method in inconel 600 alloy
Authors: Takahashi S. , Sato H. , Kamada Y. , Ara K. , Kikuchi H.
Published: December 2018

Cr concentration and the volume fraction in Inconel 600 alloy were accurately analyzed by the new magnetic method according to the magnetic properties of the ternary alloys. The depletion has a maximum at aging for 10∼h at 973 K and diminishes with longer aging. Cr depletion below 10 wt. % was observed in the aging. After aging for 100 h the depletionremarkably recovers, but it definitely remains compared with the initial state. The depleted zone extends to 300 nm from the grain boundary. These results agree well with those of a previous analysis by scanning transmission electron microscope analysis. The new magnetic method, herein reported, for evaluation of chromium depletion has nondestructive evaluation characteristics.
Simulation of hysteresis effects with the classical Preisach model in FI^2TD methods
Authors: Yuan Jing , Clemens Markus , Weiland Thomas
Published: December 2018

The paper presents a numerical method for transient magneto-quasistatic field analysis including hysteretic ferromagnetic materials. The procedure is based on a Finite Integration Implicit Time Domain(FI ^2 TD) formulation using the classical Preisach model. An hybrid scheme using the magnetic polarization update scheme for hysteretic materials and the successive approximation scheme for non-hysteretic nonlinear materials is given. Relaxation parameters are introduced to avoid convergence problems of the iterative scheme around the critical zones of the hysteresis curve. In numerical experiments with a test configuration the simulated hysteresis loops are compared with those achieved by measurements and the corresponding hysteretic losses are presented.
Effective electromagnetic properties of a nonlinear composite structure
Authors: Pinchuk Anatoliy
Published: December 2018

Nonlinear composite structures show great promise for use in optical switching, signal processing, etc. I derive an effective nonlinear dielectric permittivity of a composite structure where coated ellipsoidal nonlinear particles are imbedded in a linear host medium. The derived expression for the effective dielectric permittivity tensor follows the Clasius-Mossotti approximation. The conditions for the existence of the optical bistability effect in a coated ellipsoidal particle with a nonlinear core and a metallic shell were obtained.
An improved method for predicting magnetic power losses in SMC electrical machines
Authors: Guo Y.G. , Zhu J.G. , Zhong J.J. , Watterson P.A. , Wu W.
Published: December 2018

This paper presents an improved method for predicting magnetic power losses in electrical machines with soft magnetic composite (SMC) cores. Different formulations are used for magnetic power loss prediction with purely alternating, purely circular rotating, and elliptically rotating flux density vectors, respectively. A series of three-dimensional (3D) finite element analyses is conducted to determine the flux density locus in each element in a claw pole permanent magnet SMC electrical machine when the rotor rotates. The predicted results are compared with the experimental data of the prototype.
Coupled magneto-elastic FE model for simulation of electrical machines
Authors: Belahcen Anouar
Published: December 2018

This work presents a magneto-elastic FE model for simulation and analysis of electrical machines. The model includes magnetic non-linearity and stress dependent magnetisation. Magnetostriction and effects of geometry changes on magnetic field are accounted for. The circuit equations of the windings are solved simultaneously with the magnetic and displacement fields. Calculations without magnetostriction, show that the radial displacement of the stator core of a synchronous machine is lower than the one calculated with a non-coupled model. The difference in displacement field suggests that the magnetostriction changes due to a difference in stresses. Measured magnetostriction at different stresses is also presented for comparison.