bluuebunny/crossref_metadata_2025 huggingface dataset:
On‐line identification of continuous time‐delay systems using the genetic algorithm
Authors: Hachino Tomohiro , Yang Zi‐Jiang , Tsuji Teruo
Published: July 2007

This paper proposes a new kind of on‐line identification method of continuous time‐delay systems from sampled input‐output data. In order to track the time‐varying system parameters as well as time‐delay, the recursive linear least squares (RLS) method is combined in a bootstrap manner with the genetic algorithm (GA) which has a high potential for global optimization. The time‐delay is coded into binary bit strings and searched by the GA, while the system parameters are updated by the RLS method. Furthermore, this method (GALS method) is hybridized with the sequential nonlinear least squares method to improve the speed of convergence. Simulation results show that both the GALS and hybrid methods are efficient in the case that the system changes abruptly, and among them the hybrid method has superior convergence property to the GALs method and yields excellent estimation results in the case that the system changes with time continuously.
Stabilization of temperature dependence of verdet constant of bi‐doped garnet and development of high sensitive optical fiber magnetic field sensor
Authors: Inoue Nobukazu , Yamasawa Kazuhito
Published: July 2007

Bi‐doped garnet is a rare metal iron garnet made up of a ferrimagnetic substance, of which some portion of the rare metal element is replaced with bismuth. It illustrates a strong Faraday effect and has been applied to optical isolators. In magnetic field sensing applications, however, a shortcoming is apparent: Faraday rotation of Bi‐doped garnet reveals temperature dependencies when the garnet is not magnetically saturated. Close attention has been paid to the magnetization of each rare earth element's different temperature characteristics; garnet compositions have been investigated by calculations and experiments in order to find a garnet that shows flat temperature characteristics between −10 and 80°C. The liquid phase epitaxy (LPE) method was established to obtain a single crystal of the garnet [Bi13(Y, La)0.9Ho0.8Fe4.5Ga0.5O12]. A magnetic field sensor of fiber optic based on the Faraday effect of this single crystal is highly accurate in detecting conductor currents of power cables. The developed sensor is small and lightweight compared to conventional current transformers; additionally, optical fiber transmission of detected current signals is free from both electric and magnetic noise.
A new electric power network for effective transportation of small power of dispersed generation plants
Authors: Saitoh Hiroumi , Toyoda Jun'Ichi
Published: July 2007

This paper proposes a new electric power network that makes it possible for many types of dispersed generation plants owned by nonutility organizations to participate in an electric power market without the disadvantages of existing power utility and customers. This power network is called an open electric energy network (OEEN) because the network is open to the many types of plants for the participation. For achieving such openness, electric power storage devices, load controller at each customer and data communication network are installed in OEEN; the flow of excess electric power generated by each plant is controlled autonomously and in a distributed way. That is, the control is done by transmitting the data on excess electric power such as generation and demand point, power quality, price, etc., from each dispersed generation plant to the power storage devices and the load controllers through the communication network. Since this data‐driven power flow control is similar to the mail system for a packet with the addresses of sender and receiver, it is called packet electric power transportation.

In OEEN the storage device plays a different role from load leveling. Therefore, the way to determine the storage capacity differs from the conventional approach. In this paper, the applicability of queuing theory for determining the capacity is also discussed.
An approach to fault point identification using neocognitron and BP neural network
Authors: Zhou Diwei , Yasuda Keichiro , Yokoyama Ryuichi
Published: July 2007

This paper presents a new approach to identify a fault point in a power system on real time. Based on the topology theory, the characteristics of a fault in the power system are treated as a pattern of the fault. Therefore, the calculation complexity of traditional approaches can be avoided. The aim of the proposed method is to identify fault points through directly analyzing the type of fault. Since each type of fault has each characteristic pattern of power flow, fault points can be identified by abstracting characteristics of power flow at each node of the power system. In order to abstract fault characteristics, neocognitron in which symmetrical three phase decomposition and data normalization are calculated using power flow at each node is introduced. Thus, the impacts of voltage grade and unbalanced load can be removed. Since each neocognitron corresponds to one node of the power system, hierarchical autonomous decentralization can be realized. Therefore, the proposed approach can be applied to a large power system. Fault point location is done by BP network. Since the neuro of BP network only corresponds to the nodes of the topologized power system, the training of the neural network can be performed independently. From this point of view, the applicability and flexibility of proposed approach are high. The effectiveness and applicability of the proposed approach are demonstrated on a simple power system model.
First trial of the electric power transmission of 3.8 kV–460 kVA through the prospective power transmission model system integrated under superconducting environment (PROMISE)
Authors: Kato Takeyoshi , Tang Yue‐Jin , Shimizu Hirotaka , Hayakawa Naoki , Yokomizu Yasunobu , Matsumura Toshiro , Okubo Hitoshi , Kito Yukio , Nagafusa Toshiaki , Miyake Seiichi , Kumano Tomoyuki , Hatano Masayuki , Sato Kazuhiko , Sato Wataru
Published: July 2007

Superconducting technology is regarded as a breakthrough to future electric power transmission because of its highly densified and large transmission capability. This paper proposes a concept of the future power system composed of various superconducting apparatuses. A prototype model system called “PROMISE (PROspective power transmission Model system Integrated under Superconducting Environment)” is constructed to prove the realization of the above concept. PROMISE is composed of a superconducting transformer (60 Hz, 6/3 kV, 1000 kVA class), superconducting fault current limiter (6 kV, 200 A class), and superconducting power cable (5 m, 6 kV, 650 A class). This paper also shows that PROMISE realized the transmission of the electric power of 3.8 kV–460 kVA (50 Hz). This is the first achievement in the world. The voltage‐current synthetic test verified that PROMISE can withstand ac voltage of 6 kV while carrying ac current of 170 A (60 Hz). The ac loss of superconducting cables, the heat leak of cryostat and the core loss of the superconducting transformer are measured to estimate the transmission loss of PROMISE. These fundamental performances of PROMISE may indicate the feasibility of the future introduction of superconducting technology for electric power systems.
Two‐degrees‐of‐freedom speed control of resonant mechanical system based on H∞control theory
Authors: Morimoto Shigeo , Takeda Yoji
Published: July 2007

In industrial motor drive systems such as those used in industrial plants and robots, a torsional vibration is often generated as a result of the elastic elements present in the torque transmission systems. This vibration makes it difficult to achieve quick speed responses and may result in plant damage. Such systems are simply modeled as two‐mass mechanical systems.

The H∞control theory is applied herein to design a speed controller for the two‐mass system. This controller determines closed‐loop characteristics, including suppression of torsional vibration, rejection of torque disturbance and robust stability. Moreover, two types of two‐degrees‐of‐freedom control systems, which includes the H∞controller, are proposed to improve command response. One is based on the TDOF PI control, in which the PI controller included in the H∞controller is rearranged for the TDOF system. Another is based on the model matching feedforward control, in which the prefilter and the feedforward compensator are added to the H∞controller. The proposed control system is applied to two types of resonant mechanical systems having different inertia ratio. Several examinations demonstrate that the proposed speed control system is useful for a resonant mechanical system.
A design study of a superconductive magnet made of Bi/Ag oxide superconductors
Authors: Umeda Masaichi
Published: July 2007

A medium‐sized, high magnetic field magnet was designed using data on the mechanical properties of Bi/Ag oxide tape superconductors. Due to the poor mechanical properties of tape superconductors, the size of a superconductive magnet is limited to a narrow region of radius and magnetic field. In order to build a large superconductive magnet, key mechanical properties of the Bi/Ag oxide tape superconductors, such as irreversible strain and matrix yield strength, have to be improved significantly.
Self‐regulated self‐excited brushless three‐phase synchronous generator
Authors: Fukami Tadashi , Kawai Takahiro , Miyamoto Toshio
Published: July 2007

For lightweight and compact implementation of a generation set, many attempts have been made by some researchers to develop a brushless self‐excited synchronous generator without an ac exciter. A previous paper proposed a novel self‐excitation scheme by which the second‐space harmonic component of armature mmf is used for exciting the rotor field system. In this excitation scheme the effect of the series excitation characteristic, as well as a self‐excited and brushless implementation without an ac exciter is automatically obtained. However, in the case of system configuration of the generator already reported, voltage regulation in the inductive load condition was very large. To remove this problem, this paper presents a new system configuration of the generator with a self‐regulating feature that can compensate voltage regulation automatically. The new generator consists of a stator installing two three‐phase windings, externally connected to a load and a capacitor bank, respectively, and a rotor with field and harmonic windings.

In this paper the system configuration and theoretical concepts of the presented generator are described and detailed experimental investigations with a laboratory machine are also shown.
Test run of combined propulsion, levitation and guidance system at Miyazaki test track
Authors: Murai Toshiaki , Fujimoto Tsuyoshi , Fujiwara Shunsuke
Published: July 2007

In commercializing the superconducting Maglev system it is important to reduce the cost, especially that of ground coils constructed along the whole length of the guideway. For this purpose we have examined the combined propulsion, levitation and guidance system (PLG system) which can generate levitation, guidance and propulsion forces by the same coil. This paper describes the test run of the PLG system, whose ground coils (PLG coil) are constructed in one part of the Miyazaki test track. In designing the PLG coil, we make clear the magnitudes of the force acting both under normal and unusual conditions because the electromagnetic force, which levitates, guides, and propels the vehicle, directly acts on the magnet winding of the PLG coil. In the experiment, we examine both the performance of the vehicle and the force of a PLG coil. The measurement of the force at the PLG coil gives not only propulsion force and levitation force directly, but also guidance stiffness by sifting the measured coil. Good correlation recognized between the calculation and the experiment in the propulsion force, levitation force, and guidance stiffness proves that the required characteristics can be expected from the PLG system even under combination of propulsion, levitation and guidance.
Wavelet transform‐based signal waveform discrimination for inspection of rotating machinery
Authors: Tamaki Kenji , Matsuoka Yasuhiro , Uno Masato , Kawano Takeshi
Published: July 2007

This paper presents a new discrimination procedure of signal waveforms based on wavelet theory for the inspection of rotating machinery. The wavelet transform decomposes signals into time‐frequency space, rather than mere frequency space, limited by the uncertainty principle. This decomposition permits time‐frequency analyses and provides a more flexible means of signal processing than before.

To examine a rotary compressor pump, particular waves in the rotational load torque signals that correlate with failure modes are discriminated from one another and evaluated. To extract the focal waves, the signal is decomposed with wavelets and then only particular waves, such as impulses, are reconstructed from a selected set of wavelet coefficients. This is called time‐frequency space filtering. The wavelet local modulus maxima are used to pen a time‐frequency window through which only the focal waves can pass with high fidelity. The maxima have information of the inflection points of the wave at each resolution that represent its waveform.

The experimental results show the effectiveness of the procedure.
Investigation of equivalent circuit quantities and equations for calculation of characteristics of single‐sided linear induction motors (LIM)
Authors: Nonaka Sakutaro
Published: July 2007

We 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

Sodium‐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

A 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

This 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

This 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

This 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

In 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

Under 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

This 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

Super‐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

Recently, 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

The 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

A 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

Active 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

AC 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

An 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

Improvement 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

Solid 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

The 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

A 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.
Unsteady dynamics and organized structures from DNS over an idealized building canopy
Authors: Coceal Omduth , Dobre Adrian , Thomas T. G.
Published: July 2007

A numerical study is performed to elucidate the dominant turbulent processes that occur in urban areas. Comprehensive data from direct numerical simulations (DNS) over idealized three‐dimensional arrays of buildings are analysed to study the unsteady and organized aspects of the turbulent flow. The accuracy of the DNS is evaluated by comparing turbulence statistics with a high quality wind‐tunnel dataset. The simulation results are studied using flow visualization as well as statistical methods including quadrant analysis, space‐time two‐point correlations and conditional averaging. Three regimes of the flow are identified. First, the rough wall flow above the buildings has turbulent organized structures that resemble the ‘hairpin vortices’ and ‘low momentum regions’ that are well known to occur in the turbulent boundary layer over smooth walls. These hairpin‐like vortices contribute dominantly to vertical momentum transport. Secondly, shear layers develop over the tops of the buildings and shed structures that may sometimes impinge upon downstream buildings and drive a robust recirculation within the building canopy. These unsteady canopy‐top shear layers and their interaction with the larger eddies above provide important mechanisms for coupling with the flow within the canopy. Thirdly, the flow within the building canopy is the result of complicated interactions between the above and eddies shed off the vertical edges of the buildings, and their distortion caused by impacting buildings. Mean flow patterns around the buildings are important and lead to significant dispersive stresses. Implications for scalar transport and dispersion are briefly discussed. Copyright © 2007 Royal Meteorological Society
High resolution DNA separations using microchip electrophoresis
Authors: Sinville Rondedrick , Soper Steven A.
Published: July 2007

Planar microfluidic devices have emerged as effective tools for the electrophoretic separation of a variety of different DNA inputs. The advancement of this miniaturized platform was inspired initially by demands placed on electrophoretic performance metrics by the human genome project and has provided a viable alternative to slab gel and even capillary formats due to its ability to offer high resolution separations of nucleic acid materials in a fraction of the time associated with its predecessors, consumption of substantially less sample and reagents while maintaining the ability to perform many separations in parallel for realizing ultra‐high throughputs. Another compelling advantage of this separation platform is that it offers the potential for integrating front‐end sample preprocessing steps onto the separation device eliminating the need for manual sample handling. This review aims to compile a recent survey of various electrophoretic separations using either glass or polymer‐based microchips in the areas of genotyping and DNA sequencing as well as those involving the growing field of DNA‐based forensics.
Principles of palm olein fractionation: a bit of science behind the technology
Authors: Calliauw Gijs H. , Gibon Véronique , De Greyt Wim F.J.
Published: July 2007

Dry fractionation is a well‐established and versatile fat modification technology that can produce a broad spectrum of edible oils and fats. Due to its specific chemical composition, especially palm oil can be processed by this technology into fractions that serve as salad oils, frying oils, margarine fats. Whereas the first step of this multi‐stage production process is well understood, the edible oil industry all over the world is much more often confronted with problems in the second stage of the process, when the liquid palm olein is further fractionated. The process of palm olein crystallization is indeed a lot more difficult to control. This article therefore elaborately explains the main, fundamental causes for this sensitivity of palm olein during the fractional crystallization. It further discusses which and how components present in refined palm olein can be responsible for process instability and how they affect the quality of the end products on an industrial scale. The article also highlights which novelties and innovation in dry fractionation technology are currently under investigation.
Alternative fat sources to animal fat for pigs
Authors: Lauridsen Charlotte , Bruun Christensen Thomas , Halekoh Ulrich , Krogh Jensen Søren
Published: July 2007

The use of fats and oils in diets for pigs is of great importance due to their high energy value. As a consequence of the BSE‐crisis in the European Union, the amount of animal fat available for animal feeds has been reduced, and alternative fat sources are of increasing importance. In this paper, we review our main findings on the effects of diets with different fat sources on apparent fat digestibility in pigs. A method for quantitative measurement of fat extraction from feed and faeces has been developed, and this method has been used in a digestibility trial, in which diets added 5% of either animal fat, palm oil mix, palm oil, vegetable oil mix, coconut oil, or rapeseed oil were tested in weaned and growing pigs. It was concluded that several vegetable fat sources (palm oil mix, palm oil, coconut oil, rapeseed oil) could be used as alternatives to animal fat in pig feed, whereas fat blends should be avoided.
The electrophysiological muscle scan
Authors: Blok Joleen H. , Ruitenberg Annemieke , Maathuis Ellen M. , Visser Gerhard H.
Published: July 2007

This study aims to assess the potential of the electrophysiological muscle scan or stimulus–response curve as a diagnostic instrument. If stimulus intensity is gradually increased from subthreshold to supramaximal values, all motor units in a muscle are successively activated. Thus, by plotting response size versus stimulus intensity, an impression (scan) of the entire muscle can be obtained. We recorded 54 detailed scans from 34 patients and 11 healthy subjects, and analyzed them visually and quantitatively. The scan summarized much diagnostic information in a single picture. Specific patterns in or properties of the scan (steps, maximum, variability, decrements, stimulus intensities used) provide clinically relevant information regarding motor unit number, size, and stability, and neuromuscular transmission and axonal excitability. The scan can be recorded noninvasively in about 5 minutes and is fairly easy to interpret. Because it is built up from contributions of all functioning motor units, the scan shows if and how many large motor units are present. There is no sample bias. For these reasons, further exploration and exploitation of this tool in the clinical setting are warranted. Muscle Nerve, 2007
NMR spectroscopic identification of cholesterol esters, plasmalogen and phenolic glycolipids as fingerprint markers of human intracranial tuberculomas
Authors: Subramanian Arunachalam , Shankar Joshi Bhawani , Roy Abhijeet Deb , Roy Raja , Gupta Vivek , Dang Ramandeep S.
Published: July 2007

Detailed 1H and 13C NMR spectroscopy of lipid extracts from 12 human intracranial tuberculomas and two control brain tissue samples was performed to assess the role of lipids in the disease process. One‐dimensional and two‐dimensional NMR techniques were used to resolve the mixture of lipid components and make resonance assignments. The lipid components that could be identified in tuberculoma lipid extracts and not in control samples were: cholesterol ester, plasmalogen and phenolic glycolipids. It is proposed that the combined occurrence of these lipid components can be used as ‘fingerprint markers’ for the differentiation of intracranial tuberculoma from healthy brain tissue. Furthermore, phenolic glycolipids present in intracranial tuberculomas may have diagnostic significance in differentiating them from other disease conditions of the central nervous system such as malignant tumors. Copyright © 2007 John Wiley & Sons, Ltd.
RAFT synthesis of a water‐soluble triblock copolymer of poly(styrenesulfonate)‐b‐poly(ethylene glycol)‐b‐poly(styrenesulfonate) using a macromolecular chain transfer agent in aqueous solution
Authors: Peng Zhiping , Wang Dandan , Liu Xinxing , Tong Zhen
Published: July 2007

Triblock copolymers of poly(styrenesulfonate)‐b‐poly(ethylene glycol)‐b‐poly(styrenesulfonate) with narrow molecular weight distribution (Mw/Mn = 1.28–1.40) and well‐defined structure have been synthesized in aqueous solution at 70 °C via reversible addition‐fragmentation chain transfer polymerization. Poly(ethylene glycol) (PEG) capped with 4‐cyanopentanoic acid dithiobenzoate end groups was used as the macro chain transfer agent (PEG macro‐CTA) for sole monomer sodium 4‐styrenesulfonate. The reaction was controllable and displayed living polymerization characteristics and the triblock copolymer had designed molecular weight. The reaction rate depended strongly on the CTA and initiator concentration ratio [CTA]0/[ACPA]0: an increase in [CTA]0/[ACPA]0 from 1.0 to 5.0 slowed down the polymerization rate and improved the molecular weight distribution with a prolonged induction time. The polymerization proceeded, following first‐order kinetics when [CTA]0/[ACPA]0 = 2.5 and 5.0. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3698–3706, 2007
End group effect on the thermo‐sensitive properties of well‐defined water‐soluble polystyrenics with short pendant oligo(ethylene glycol) groups synthesized by nitroxide‐mediated radical polymerization
Authors: Jiang Xueguang , Zhao Bin
Published: July 2007

The effects of hydrophobic chain end groups on the cloud points of thermo‐sensitive water‐soluble polystyrenics were investigated. Well‐defined poly (4‐vinylbenzyl methoxytris(oxyethylene) ether) (PTEGSt) and poly(α‐hydro‐ω‐(4‐vinylbenzyl)tetrakis(oxyethylene)) (PHTrEGSt) were prepared by nitroxide‐mediated radical polymerization using α‐hydrido alkoxyamine initiators including two monomer‐based initiators. The polymers were reduced with (n‐Bu)3SnH to replace the alkoxyamine end group with hydrogen. In the studied molecular weight range (Mn,GPC = 3000 to 28,000 g/mol), we found that the hydrophobic end groups decreased the cloud point by 1–20 °C depending on the molecular weight and the largest depression was observed at the lowest molar mass. The cloud points of PTEGSt and PHTrEGSt with two hydrophobic end groups, phenylethyl and alkoxyamine, exhibited a monotonic increase with the increase of molecular weight. For polymers with only one hydrophobic end group, either phenylethyl or alkoxyamine, the cloud point initially increased with the increase of molecular weight but leveled off/decreased slightly with further increasing molar mass. For polymers with essentially no end groups, the cloud point decreased with the increase of chain length, which represents the “true” molecular weight dependence of the cloud point. The observed molecular weight dependences of the cloud points of polystyrenics with hydrophobic end group(s) are believed to result from the combined end group effect and “true” molecular weight effect. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3707–3721, 2007