bluuebunny/crossref_metadata_2025_split huggingface dataset:
Investigation of equivalent circuit quantities and equations for calculation of characteristics of single‐sided linear induction motors (LIM)
Authors: Nonaka Sakutaro 
Published: July 2007

AbstractWe wish to derive an improved analytic method and performance equations for estimation of the characteristics and the design of a reasonable LIM. An approximation that simplifies the estimation of the performance of the single‐sided linear induction motor is presented. The original equations were derived from the two‐dimensional electromagnetic analysis and the equivalent circuit quantities, such as the magnetizing reactance, the secondary resistance and reactance, and are given in combination with hyperbolic and trigonometric functions of complex number.In this paper, these functions are approximated by the MacLaurin's expansion, and the equivalent circuit quantities are expressed by polynomial approximations. The computed thrust, primary current, power factor and efficiency‐slip curves for the test of urban‐transit SLIM at Kyushu University, calculated from the original equation and the new approximation, show a close agreement. The magnetizing reactance plays an important role in the LIM performance and the larger it is, the better. The ratio of air gap length to pole pitch is the key to the performance of the LIM.
Deterioration of mica‐alumina composite insulations at high temperatures
Authors: Ishida Masayoshi , Ikeda Yasuyuki , Mitsui Hisayasu , Kumazawa Ryoji , Kuroki Toshitaka 
Published: July 2007

AbstractSodium‐immersed electromagnetic pumps will be critical for commercialization of fast breeder reactors in the near future. In order to operate the pumps in molten sodium satisfactorily, it is indispensable to have electrical insulation that can withstand temperatures of above 500°C for a prolonged period of time.Several mica‐alumina composite insulation types were aged under a high electric field in nitrogen at high temperatures. All composite insulations aged at 750°C experienced dielectric breakdown after around 1000 hours. However, it was possible to detect the onset of dielectric breakdown by monitoring the ac current. Mica splittings insulation was found to be superior in dielectric performance to mica paper insulation. Thermal degradation contributed to the dielectric deterioration of these insulations.
Diagnostic methods for GIS‐insulated switchgear insulation using external antenna
Authors: Kimura Takashi , Harunami Takao , Konma Naohiro , Saitoh Kazutoshi 
Published: July 2007

AbstractA partial discharge detection system was developed using an external antenna that can be easily installed on the outside of the GIS. The antenna is fitted closely to the outer circumference of the insulation spacer, and it can detect electromagnetic radiation of the partial discharge with high sensitivity.To have high sensitivity even in noisy condition, three kinds of methods that can eliminate external noise effectively were verified. In addition, the locating method of defect based on distance attenuation was confirmed. Actually, the insulation monitoring system which employs the antenna is used in a substation that had already been installed. At present, it is operating satisfactorily.
Development of peak load forecasting system using neural networks and fuzzy theory
Authors: Ueki Yoshiteru , Matsui Tetsuro , Endo Hiroshi , Kato Tatsuyosi , Araya Ryosaku 
Published: July 2007

AbstractThis paper presents a peak load forecasting system using multilayer neural networks and fuzzy theory. Electric load forecasting in power systems is a very important task from the perspective of reliability and economic operation. Daily peak load forecasting is one of the basic operations of generation scheduling for the following day. Therefore, many statistical methods have been developed and used for such forecasting even though it has been difficult to construct a proper functional model.The developed system is applied by neural network and fuzzy theory to forecast for daily, weekly and monthly peak load. The system consists of an engineering workstation (EWS) and a personal computer (PC). The EWS is for learning and data‐bases, and the PC is for man‐machine interface such as forecasting operation.The system has been used since June 1993. The result evaluated with an absolute mean error is 1.63 percent for 10 months. From the results shown here, the system applied by neural network and fuzzy theory has high validity.
Monostructure touch sensor with multifunction for discrimination of material properties
Authors: Li Desheng , Shida Katsunori 
Published: July 2007

AbstractThis paper describes the development of a mono‐structure touch sensor that has three kinds of sensing functions for discriminating materials. The sensor consists of two spiral metallic lines on a thin insulating substrate and has four terminals. When the two lines are used as two coils, the sensor has the property of inductance. When the two lines are used as two parallel electrodes, the sensor has the property of capacitance. When one spiral metallic line is used as a heater and another is used as a resistor, the sensor has the property of a temperature sensor.The proposed sensor is used to discriminate typical materials such as iron, aluminum, copper, bronze, gum, wood, acrylic resin, styrene foam, etc. The experiments show that the sensor has considerably high potential in discriminating materials, indicating that the sensor would be a promising candidate for developing an artificial skin tactile sensing system in the future.
High torque induction motor with rotating magnets in the rotor
Authors: Shibata Yoshiyuki , Tsuchida Nuio , Imai Koji 
Published: July 2007

AbstractThis paper describes a new type high torque induction motor which has the rotating magnets in the rotor. The motor basically consists of a usual stator, cylindrical rotor, and inner cylinder of which the surface is covered by a set of magnets. The rotor turns at somewhat less than synchronous speed. The inner cylinder with magnets can revolve freely against a rotor shaft. The magnets revolve synchronized by the rotating magnetic field induced by the stator current. The magnets make the flux in the rotor. Then we can expect torque increase by the increase of the flux. The results of magnetic field analysis indicate the flux is increased.In the experimental results of a test motor which is a 400 W prototype machine, we have obtained the torque increase by approximately 20 percent as anticipated in the magnetic field analysis. Moreover, test results show improvements of efficiency and power factor in the motor operations. The efficiency of the test motor is obtained as high as 10 percent at the rated output over those of a same size conventional induction motor. Although power factor of conventional induction motors is lagging at all times, the test motor can be operated with near unity, leading or lagging by adjusting the ac supplied source voltage.
Basic studies of film transformer
Authors: Midorikawa Yoichi , Hayano Seiji , Saito Yoshifuru 
Published: July 2007

AbstractIn order to realize light and small power supplies, this paper proposes a film‐shape transformer called film transformer. The basic operating principle of this transformer is the skin effect similar to those of the coreless transformer previously exploited by the authors. Both the primary and secondary coils composed of thin‐film conductors are arranged coaxially on the one‐layer film base, and the film transformer is constructed by the lamination of these films.In this paper, experimental as well as numerical studies are carried out about basic characteristics of the film transformer in order to examine possibilities in practical use. As a result, it is shown that the film transformer may be applicable to high‐frequency switching power supplies.
A flexible decision method for transmission system expansion planning considering power interruption cost
Authors: Yamashiro Susumu , Kinoshita Hisashi , Nakamura Koichi , Kimura Mitsugu , Fukushima Tomoyuki 
Published: July 2007

AbstractUnder the current deregulation of the electric utility industry, power system planning has become more complex. System planners are required to study how to use available resources to meet customer's demand economically with acceptable reliability and quality. Integrated resource planning has emerged recently as one effective approach for this problem, and the approach has been expanded to include the value of reliability, that is, power interruption cost.This paper is aimed at developing a flexible decision method to select a favorable plan among various transmission system expansion alternatives, not only from a power supplier's viewpoint, but also from the customer's perspective, including cost of interruption.Bellman‐Zadeh's maximizing decision using a fuzzy decision set is applied as a flexible decision method which is able to reflect the planner's intentions. Numerical examples are given to ascertain the effectiveness of the proposed method.
Three‐dimensional magnetic field analysis of a system containing coil currents and iron elements using the virtual current method
Authors: Takechi Moriaki 
Published: July 2007

AbstractThis paper proposes a method of analyzing the three‐dimensional magnetic field of a system containing coil currents and magnetic substances using virtual currents. Various methods have been presented for analysis of a three‐dimensional static field in an open boundary space; however, in a large‐scale problem, the computational size easily exceeds the acceptable limit of computing time and machine capacity. The basic idea of the proposed method is to divide the whole region into interior and exterior regions with an artificial boundary and to substitute virtual currents for source currents and magnetic substances within the boundary. The use of virtual currents reduces the number of elements to be analyzed and shortens computing time while maintaining accuracy of analysis. In this paper, a method of determining virtual current is proposed and principal parameters of virtual currents that affect accuracy of analysis are examined. The conditions under which the virtual current method can be applied are examined through analysis of errors introduced by the virtual current method. This method has been applied to analyze magnetic shielding of a magnet for magnetic resonance imaging. This example proves that the proposed method is effective in reducing the scale of analysis and computing time.
Analysis and characteristics of a permanent magnet‐type bearingless motor
Authors: Ooshima Masahide , Miyazawa Satoru , Deido Tazumi , Chiba Akira , Nakamura Fukuzo , Fukao Tadashi 
Published: July 2007

AbstractSuper‐high‐speed and high‐power electric machines are required for turbomolecular pumps and spindle drives. High rotational speed and high‐power drives can be achieved with bearingless motors. In this paper, a bearingless motor with principles of permanent magnet‐type synchronous motors is proposed. High‐power factor and high efficiency can be expected in permanent magnet‐type bearingless motors. The proposed bearingless motor is a 4‐pole permanent magnet synchronous motor, in which additional 2‐pole windings are wound together with 4‐pole motor windings in stator slots. With currents of 2‐pole windings, radial magnetic forces are produced to support a rotor shaft. Principles of radial force production of surface‐mounted permanent magnet bearingless motors are analyzed mathematically. The relationships between radial forces and the permanent magnet thickness were derived. From these relationships, the optimal permanent magnet thickness to produce radial forces efficiently is found. A test machine was built to confirm the relationships of radial forces, currents and voltages.
Reduction control of induction motor vibration with pulsating load by repetitive control using an acceleration sensor
Authors: Higuchi Shinichi , Ishida Muneaki , Hori Takamasa 
Published: July 2007

AbstractRecently, the V/F control drive system of the induction motor has been applied widely to the drive of compressors, pumps, etc., because it is very simple and basically requires no speed sensors. However, if the V/F controlled induction motor drives a pulsating load such as the compressors, the rotational speed of the motors is fluctuated considerably and the motor frame vibrates due to the pulsating load torque. When frequency of the torque pulsation is especially close to the resonant frequency of the mechanical system, large vibration and acoustic noise are produced.In this paper the authors propose a method to reduce the vibration of the V/F controlled induction motor with a fluctuated load by repetitive control using an acceleration sensor. The acceleration sensor is easy to install on the motor or load frame. The repetitive control is considered effective for reduction of the vibration, as the load torque varies periodically. Effectiveness of the proposed method is confirmed by approximate analysis and experiments.
A technique of parallel connections of pulsewidth‐modulated NPC inverters by using current‐sharing reactors
Authors: Ueda Fukashi , Matsui Keiju , Tsuboi Kazuo , Asao Masahiro , Kobayashi Tadashi , Watanabe Makoto 
Published: July 2007

AbstractThe neutral‐point‐clamped (NPC) PWM inverters have many advantages such as the ability to operate the motor with nearly sinusoidal current waveforms. For this reason, in larger‐capacity inverter systems, NPC PWM inverters using the GTOs, etc., have also been put into practical use because of great advantages to large‐capacity ac motor drives such as lower ripple currents and higher output voltages. With the spread of applications, still larger‐capacity inverters also are expected. However, since the capacities of such switching devices are insufficient, a certain technique and controlling method are proposed for the parallel connections of NPC inverters. The output voltage waveforms of the proposed inverter have certain voltage levels, and thus it is anticipated that it will be difficult to analyze the output harmonics. For such waveforms of output voltage and current‐sharing reactor, a frequency analysis approach is described whose results are verified by experiments.
Error tracking mode AC current waveform control method for three‐phase self‐commutated voltage source power converters
Authors: Ohshima Masaaki 
Published: July 2007

AbstractA novel design theory for a three‐phase self‐commutated power conversion system (PCS) to perform as an ac current source is proposed. In this new ac current waveform control method termed error tracking mode, the switching instructions of main devices are decided only by the error function of ac current at every data sampling time that comes in a constant period. The performance is theoretically evaluated. Simulation by SPICE also is executed and the characteristics are inspected.Error tracking mode has the following attractive features. It can treat two arbitrary current waveforms as target functions of two‐phase arbitrary ac currents. The error between actual ac current value and the objective function value can be controlled and guaranteed to be less than an arbitrary value, which is given beforehand. All control components can be digitized. The minimum continuous on and off time of main devices is guaranteed in advance. No special starting control is necessary because actual ac currents are guaranteed to start tracking the target functions automatically. Error tracking mode makes contributions to improve precision in current control and to reduce current harmonics of self‐commutated voltage source power converters.
Industrial application of position sensorless active magnetic bearings
Authors: Mizuno Takeshi , Bleuler Hannes , Tanaka Hiroaki , Hashimoto Hideki , Harashima Fumio , Ueyama Hirochika 
Published: July 2007

AbstractActive magnetic bearings (AMBs) are applied to turbomolecular pumps (TMPs) and milling spindles. However, their application areas are limited because they are costlier and require larger space than conventional mechanical bearings. Omitting position sensors from AMBs is one of the promising methods to solve such problems. An additional merit is that rotors can be shortened to have a higher critical speed by removing sensor targets from the rotor. The sensorless operation of AMBs has already been achieved in several instruments developed for experimental study. In this research, the sensorless magnetic suspension method is applied to a TMP manufactured as an industrial product, and it is demonstrated that sensorless AMBs can suspend a high‐speed rotor.
Reduction in AC partial discharge from PMMA films doped with an electron donor dye
Authors: Fukuchi Yasunori , Yamano Yoshiaki 
Published: July 2007

AbstractAC partial discharges from PMMA films doped with various dyes have been investigated. In this paper, the following three dye films were prepared by the solution‐casting method: p‐aminoazobenzene (Ab); p‐nitrobenzeneazo‐resorcinol (Nb); and methyl‐yellow (My). AC partial discharges were investigated by placing a 100‐μm thick film on a 3‐mm thick PMMA plate between a spherical high‐voltage electrode and planar ground electrode.The number of discharge pulses and total electric charge discharged from an Ab‐doped PMMA film was less than 50 percent of those without Ab. AC partial discharges were suppressed at electric fields which were slightly higher than the electric field for the onset of ac partial discharges. However, ac partial discharge characteristics of PMMA films doped with other dyes were not affected.Attempts have been made to elucidate mechanisms for the reduction in ac partial discharges on the PMMA film doped with Ab by examining the distribution of surface potential at zero crossovers. The ionization of Ab dye, which is an electron donor, is attributed to the reduction in ac partial discharges on the Ab‐doped PMMA film.
New after‐laying test methods for XLPE cable lines
Authors: Uchida Katsuki , Kobayashi Shin'Ichi , Kawashima Takao , Hirotsu Ken'Ichi , Inoue Hitoshi , Tanaka Hideo , Sakuma Susumu 
Published: July 2007

AbstractAn after‐laying test is required to demonstrate the soundness of XLPE underground cable lines with joints. AC voltage application is desirable for the test; however, the equipment for ac application must be very large because it must supply large capacitive current for cables. DC voltage is normally applied, which can be supplied with small equipment; however, the effectiveness of the dc application is questioned because the electrical stress distribution is quite different from that with ac application and, moreover, dc application could damage insulation properties of cables.The authors targeted the Oscillating Wave (OSW) method and the Very Low‐Frequency (VLF) method as alternative after‐laying tests. They first developed modeling methods of various defects on underground cable lines and applied OSW and VLF to these defect models. They found that OSW and VLF methods have higher fault detection capability than dc voltage application. They also demonstrated that the defects which can be easily detected with the OSW method are difficult to detect with the VLF method and vice versa. They showed that serial application of both methods highly improve the fault detection ability for XLPE underground cable lines.
Improvement of power system stability using multivariable excitation control
Authors: Hirayama Kaiichiro , Uemura Yuichi 
Published: July 2007

AbstractImprovement of power system stability is the most important issue of generator excitation control. The combination of thyristor excitation with ΔP‐PSS is usually applied to recently installed very large turbogenerators. This power system generator (PSS) is not always effective for wide‐range operation of generators or for various changes of power system line impedance. The application of the optimal control theory, especially the multifeedback signal resulting from the Riccati equation has been studied and reported in many papers. These papers, however, do not clearly describe how to set performance index values and the studies reported in them also use inadequate signals. This paper presents a method to set the performance index values to make adequate feedback signals for selecting actual control on the application of the Riccati equation. Further, the developed PSS using multifeedback signals is applied to actual very large turbogenerators after confirming the performance of effective damping for power oscillation.
Analysis and performance improvement of motor speed control system with nonlinear friction
Authors: Iwasaki Makoto , Kitoh Yoshiaki , Matsui Nobuyuki 
Published: July 2007

AbstractSolid friction in machine elements is one of the dominant nonlinearities affecting the control accuracy of servo drive systems. Many schemes, including feedforward control, observer‐based control and repetitive learning control have been proposed to compensate for nonlinear friction. These schemes show superior performance compared to that of the conventional P‐ and/or PI‐controller; however, friction model errors and bandwidth restriction of the observer cause compensation errors, thus decreasing control accuracy.This paper presents a new control algorithm for performance improvement of a motor speed control system having nonlinear friction. By analyzing characteristics of conventional compensation control schemes during velocity reversal, the relation between control parameters and control accuracy is examined so as to explore problems with each scheme. Based on these analyses, a new feedforward control algorithm is proposed. The proposed algorithm is verified by analyses of control characteristics and experiments using a prototype. Experimental results show the superior performance improvement of the proposed algorithm.
Synthesis of 3‐Phenyl‐4‐piperidones from Acetophenone by Shapiro and Aza‐Michael Reactions and Their Further Derivatization
Authors: Rosiak Anna , Hoenke Christoph , Christoffers Jens 
Published: July 2007

AbstractThe Shapiro reaction of acetophenone is the key in a convenient three‐step access to a divinyl ketone which is further transformed by double aza‐Michael reactions with primary amines into N‐substituted 3‐phenyl‐4‐piperidones. In the case of N‐benzyl and N‐allyl derivatives, the piperidine nitrogen atom can be deprotected and further functionalized, for example, by carboxamide, carbamate, or urea formation.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Comparison of selective hedging and options strategies in cattle feedlot risk management
Authors: Schroeder Ted C. , Hayenga Marvin L. 
Published: July 2007

AbstractA cattle feedlot marketing simulation model was developed and used to evaluate the performance of various feedlot marketing strategies. The marketing analysis included corn, feeder cattle, and fed cattle integrated marketing alternatives. A variety of strategies were compared including hedging and put option purchasing as signaled via profit margins or price forecasts. The results indicate that cattle feeders could have historically increased profitability and decreased the variability of profits through selective marketing by using either profit margins or price forecasts to signal market positions as compared to cash marketing strategies. In addition, several strategies were found that stochastically dominated cash marketing.