bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characteristics and classification of high‐current fault arcs on distribution systems
Authors: Goda Yutaka , Okazaki Masayuki , Inaba Tsuginori 
Published: July 2007

AbstractWhen a fault occurs on transmission or distribution systems due to lightning or overvoltage, often an arc discharge occurs at the fault point. The arc discharge, which is caused by a fault current, has a high current, high temperature, strong light emission, etc., thus it sometimes causes heavy damages to electric power equipment.The arc discharge is influenced by the conditions around the arcs, i.e., gas, insulation materials, gap length, weather, etc. Also, the arc voltage along the arc column indicates the characteristics of the arc. If the voltage waveforms of the arcs caused by the fault on transmission or distribution systems are classified, it is possible to find the location and the equipment where the fault occurred.In this paper, the arc voltage data in 6‐kV class XLPE cables and 6‐kV class overhead lines are analyzed and an artificial neural network method is applied to classify the arc voltage waveforms. The results obtained from the six artificial neural networks developed show that the artificial neural network method is effective for classification of arc voltage waveforms if adequate input parameters are selected.
Fast power flow for radial power systems using parallel processing
Authors: Fukuyama Yoshikazu , Nakanishi Yosuke 
Published: July 2007

AbstractPower flow calculation is a basic tool for power system planning and control which includes power flow analysis, voltage control, service restoration, network reconfiguration, and other operation functions for control centers. In these applications, it is very important to solve the power flow problem as efficiently as possible.This paper presents a fast power flow using parallel processing for radial power systems. This method can be applied to secondary systems and distribution systems. Since it uses as state variables only active and reactive power injection to main lines and laterals, reduction of the number of state variables can be realized. Radical networks are mapped to the tree structure of parallel processor systems in the proposed method. The forward/backward sweep approach is realized by communication from a root processor to leaf processors and vice versa. Using the mapping scheme of the proposed method, each processor has to communicate with only neighboring processors. The proposed method is evaluated on various radial systems with promising results.
Suppression effects of active power filter on harmonics of distribution system including capacitors
Authors: Oku Kiyoshi , Nakamura Osamu , Inoue Jun‐Ichi , Kohata Masakasu 
Published: July 2007

AbstractVoltage distortion of 6.6‐kV distribution systems has been increasing recently especially in commercial areas. Harmonic currents of certain orders are amplified and voltage distortions are generated by the resonance between system impedance and static capacitor under the leading power factor condition.This paper describes the results of a test on suppression effects on model systems and an actual system. The effect of the use of an active power filter on the resonant harmonics of the system including capacitor was verified.
Medium‐size distribution transformer diagnostics
Authors: Susaki Yoshiki , Nakamura Osamu , Kawachi Fumio , Yamaoka Masayoshi , Nishimura Takeshi , Kuriyama Tadashi 
Published: July 2007

AbstractAn improved method of degradation diagnosis for medium‐size distribution transformers is described. The proposed method uses refined criteria of degradation for specific application for 200‐ to 1000‐kVA range transformer diagnostics. The new criteria were established with a 95 percent confidence limit of data after extensive case studies focusing on the relationship between the amounts of CO and CO2 generated in transformer oil and the length of operating time of the transformer. Another feature of this diagnostic technique is the provision of a capability to estimate the thermal history of the insulation material by examining the amounts of certain trace products of decomposition present in the transformer oil. For this purpose, a thermal history discriminant chart was devised by application of a canonical discriminant analysis method.
Transmission line tower models in frequency domain
Authors: Kato Shohei , Mochizuki Azuma , Zaima Eiichi 
Published: July 2007

AbstractThis paper proposes a transmission line tower model in frequency domain for back‐flashover analysis, which has a uniform characteristic impedance and a uniform propagation constant. Most conventional tower models are constructed as a constant and uniform parameter transmission line that is independent of frequency. However, the authors' models have the frequency dependency of the characteristic impedance and the propagation constant to express the frequency characteristic of the transmission line tower.Two models, a cylinder model and a four‐frames model, were investigated to simulate the tower. Their surge responses were computed by numerical electromagnetic field analysis based on the moment method. From the results, the two‐port circuit constants were calculated in the frequency domain, and the characteristic impedance and the propagation constant are derived from them. The complex artificial oscillations appeared in frequency dependency of the parameters because the parameters were calculated numerically. The equations with analytical form were obtained by approximating with a smooth curve to the oscillations. It is possible for the equations to represent the transmission line constants as a function of geometrical parameters such as the tower height and the radius. Close agreement was found between the surge response computed by the numerical electromagnetic field analysis and the result calculated by inverse Laplace transformation of the analytical equations. To prove the model, the experimental results were compared with the computed ones of the cylinder model that has arms, and it was shown that the new model agrees closer with the experiment than conventional transmission line models.
Transient analysis of an advanced static var compensator using quad‐series voltage‐source PAM inverters
Authors: Tominaga Shinji , Fujita Hideaki , Akagi Hirofumi 
Published: July 2007

AbstractThis paper deals with an advanced static Var compensator (ASVC) using quad‐series voltage‐source PAM inverters. The ASVC consists of four three‐phase voltage‐source inverters with a common dc capacitor and four three‐phase transformers, each primary winding of which is connected in series with each other. Each inverter outputs a square‐wave voltage, while the synthesized output voltage of the ASVC has a 24‐step wave shape. This results not only in a great reduction of harmonic currents and dc voltage ripples but also in fewer switching and snubbing losses.In this paper, transient analysis is performed with the focus on the response of reactive power and the resonance between the dc capacitor and ac reactors. Experimental results obtained from a small‐rated laboratory model of 10 kVA are also shown to verify analytical results based on thep‐qtransformation. The analytical results help in the design of system parameters such as the capacity of the dc capacitor and feedback gains.
A static voltage fluctuation compensator for AC electric railway using self‐commutated inverters
Authors: Uzuka Tetsuo , Hase Shin‐Ichi , Mochinaga Yoshifumi , Takeda Masatoshi , Miyashita Takeshi , Ueda Tsuyoshi 
Published: July 2007

AbstractIn this paper, the authors describe the basic configuration of an RPC (Railway Static Power Conditioner), its compensation principles and successful test results (using a small model of RPC).An ac electric railway is placed under a rapidly changing single‐phase load. To avoid a voltage fluctuation under single‐phase loads, electric power is received from a large source. At a feeding substation, three‐phase electric power is transformed into two kinds of directional single‐phase feeding electric power.The authors have already proposed a static voltage compensator for the ac electric railway, called “RPC.” The RPC links a pair of feeding circuits, using two self‐commutated inverters.At the substation, the RPC accommodates an active power in the directional pair of feeding circuits to balance three‐phase power, and possess a reactive power to regulate a three‐phase voltage fluctuation. At a sectioning post, it can compensate for voltage drop using reactive power. It can also act as an active filter to compensate for harmonics.The authors have made a small model (220 V, 20 kVA) of the RPC, and report on the test results obtained using this small model under various conditions. The results indicate that the RPC can accommodate single phase loads, such as transformers and thyristors, can handle an exciter rush current from a transformer, can compensate for harmonics, and so on.
Self‐excited synchronous induction motor
Authors: Fukami Tadashi , Ishizaka Takashi , Miyamoto Toshio 
Published: July 2007

AbstractA synchronous‐induction motor, with the features of both a synchronous motor and a wound‐rotor induction motor, far excels other synchronous motors in starting characteristics. However, a major drawback of the synchronous‐induction motor is the need for an excitation power supply with low‐voltage, large‐current power rating. For this reason, its driving equipment becomes large, and increases overall cost.This paper proposes a new synchronous‐induction motor, absent the problems involved in making the motor a self‐excited type. It employs the second‐space harmonic component of armature reaction field to obtain the self‐excitation of the field system, and installs a harmonic winding, which is used for extraction of an excitation power, in the rotor. This new self‐excited motor has the following advantages: (1) the driving equipment is small, since no excitation power supply is involved; and (2) due to the effect of the series characteristic by which the field current varies in proportion to the load current automatically, the motor can be operated with a good power factor.In the present paper the structure and operating principle of the new motor are explained and the basic characteristics are also investigated by means of a simple analysis and experimental results with a 1.5‐kV trial machine.
Damping enhancement of multimachine power system using adaptive generator control system with neural networks
Authors: Kobayashi Takenori , Morioka Yasuo , Yokoyama Akihiko 
Published: July 2007

AbstractThe authors proposed a nonlinear adaptive generator control system with neutral networks for improving damping of power systems, and showed its effectiveness in a one‐machine infinite bus test power system in a previous paper. The proposed neurocontrol system adaptively generates appropriate supplementary control signals to the conventional controllers such as the automatic voltage regulator and speed governor so as to enhance transient stability and damping of the power system.In this paper, the applicability of the proposed neurocontrol system to multimachine power systems is discussed. Digital time simulations are carried out for a 4‐machine test power system, where one or several synchronous generators is equipped with the neurocontrol system. As a result, also in the multimachine power system, the proposed adaptive neurocontrol systems improve the system damping effectively and they work adaptively against the wide changes of the operating conditions and the network configuration.
Development of transient stability controller system (TSC) based on on‐line stability calculation
Authors: Ota Hiroji , Inoue Toshihiro , Ito Hisanori , Fukushima Nobuo , Omata Kazuya , Morita Ken‐Ichi , Kokai Yutaka 
Published: July 2007

AbstractA new transient stability controller system (TSC) based on on‐line transient stability calculation has been developed. The TSC system prevents the power system from wide‐area blackout by shedding generators optimally when a serious fault occurs. This system consists of a central processing unit (TSC‐P), and four local units for fault detection (TSC‐C), and seventeen units for generator shedding (TSC‐T). The TSC‐P selects optimal generators to be shed for stabilization based on on‐line transient stability calculation for contingencies at 500 kV lines and buses every five minutes. The results are transmitted to the TSC‐Cs periodically. Should any fault occur, only one TSC‐C will detect the fault occurrence and send control signals to the TSC‐Ts which actually generate shedding signals. To realize the TSC system, essential are fast stability evaluation methods for a large number of contingencies and effective selection methods of optimal generators to be shed for stabilization.This paper presents total algorithms applied in the TSC‐P, the results of algorithm verification tests using a prototype system combined with a large‐scale analog simulator, and the characteristics of the actual system.
Forecasting of cloud‐to‐ground discharge by SAFIR
Authors: Matsui Toshiaki , Adachi Mikio , Onuki Jun , Kawasaki Zen‐Ichiro , Wada Masakazu , Matsuura Kenji 
Published: July 2007

AbstractThe possibility of forecasting cloud‐to‐ground discharges is investigated. It is empirically well known that the cloud‐to‐ground discharges occasionally follow the cloud discharges, and the objective of this paper is to determine if it is true or false, using the SAFIR data for a few years. Since the development of thunderclouds is determined by the movement of its active area, the coordinate fixed to the moving thunderclouds is applied for analysis.The analyzed results suggest that forecasting cloud‐to‐ground discharges with 10‐min advance notice for both summer and winter thunderstorms is a possibility.
Development of weatherproof mobile impulse voltage generator and its application to experiments on nonlinearity of grounding resistance
Authors: Morimoto Atsuo , Hayashida Hiroshi , Sekioka Shozo , Isokawa Masahiko , Hiyama Tatsuya , Mori Hitoshi 
Published: July 2007

AbstractThis paper describes a newly developed impulse voltage generator (IG). It has the following features: (1) The IG consists of three components (a 1.6 MV unit, a 1.4‐MV unit and a base box); this facilitates mounting on 10‐ton trucks, therefore making it easier to move to a test field. (2) Capacitors, discharge gaps and a control unit are enclosed in fiber‐reinforced plastics, making it possible to use the IG in all weather. (3) The IG can generate several ten kA when a load is a few ten Ω. (4) Composition of the circuits for lightning/switching impulse voltage/current tests can be easily done by changing the damping and discharge resistance cassettes. Control and data acquisition are made by personal computer.For IG application during an outdoor test, this paper presents the characteristics of resistances of a 77‐kV substation grounding and a concrete pole when applying a high impulse current. The resistances are dependent on the crest value of the applied current.
Three‐phase current‐fed type converter with direct control of instantaneous current vector
Authors: Ohnishi Tokuo , Minamoto Yoshikazu 
Published: July 2007

AbstractA new PWM technique for the current‐fed PWM converter is proposed. As the control variables, the instantaneous active and reactive powers are used instead of the line current. They are proportional to the instantaneous active and reactive current vector. The switching state of the PWM converter is given by the selection method of the appropriate current vector among the seven kinds of the current vectors with the zero current vector. The active current is controlled by the zero current vector and the reactive current depends on the kind of selected current vector. These variables basically are controlled by PWM switching from two kinds of hysteresis comparator. In addition to this, the compensation of the filter circuit can be obtained automatically by the PWM control based on the active and reactive current detected from the source current.In this paper, the principle of the PWM technique for the current‐source PWM converter is proposed. Then, some simulation results are shown. After that, the feasibility of the system is verified by experimental results.
Application of SiC‐Si functionally gradient material to thermoelectric energy conversion device
Authors: Okano Kazuo , Takagi Yoshimitsu 
Published: July 2007

AbstractBecause of its high–temperature chemical stability, SiC ceramic is a promising material for high‐temperature device applications such as thermoelectric energy converters. However, the electrical conductivity of SiC ceramic is too low for it to be used as a thermoelectric energy converter at the cold junction. Therefore, we propose a SiC‐Si functionally gradient material (FGM) in order to improve the electrical conductivity of the SiC ceramic at the cold junction.An SiC rod was fired in a temperature gradient furnace. One end of the SiC rod was maintained at 2473 K and the other end was maintained at 1973 K for 30 min. After firing, the porous SiC edge fired at 1973 K was dipped into molten Si in order to infiltrate molten Si into the porous SiC.The microstructure of the FGM is classified into three regions: the SiC‐Si composite material; the porous SiC ceramic; and the densified SiC ceramic. The electrical conductivity, the Seebeck coefficient and the thermal conductivity for each region of SiC‐Si FGM was measured at 300 K; a figure of merit was calculated. The figure of merit of the SiC‐Si FGM at the cold junction, at room temperature, was 108 times higher than that of a nongradient SiC ceramic.
Synthesis of Phosphorylated, Conjugation‐Ready Di‐, Tri‐ and Tetrasaccharide Fragments of the O‐Specific Polysaccharide of V. cholerae O139
Authors: Ruttens Bart , Saksena Rina , Kováč Pavol 
Published: July 2007

AbstractThe fragments described contain a galactose residue with cyclic 4,6‐phosphate and are equipped with an amino‐functionalized spacer, allowing further derivatization or directconjugation to suitable carriers. The core Gal‐(1→3)‐GlcNAc disaccharide was obtained by condensation of 8‐azido‐3,6‐dioxaoctyl 2‐acetamido‐4,6‐O‐benzylidene‐2‐deoxy‐β‐D‐glucopyranoside with 2,3,4,6‐tetra‐O‐acetyl‐α‐D‐galactopyranosyl bromide under Helferich conditions. Reductive opening of the benzylidene acetal, followed by deacetylation and selective benzylation gave 8‐azido‐3,6‐dioxaoctyl 2‐acetamido‐6‐O‐benzyl‐3‐O‐(3‐O‐benzyl‐β‐D‐galactopyranosyl)‐2‐deoxy‐β‐D‐glucopyranoside, which was regioselectively phosphorylated to give two isomeric 4,6‐cyclic 2,2,2‐trichloroethyl phosphates. The (R)‐phosphate was subjected to catalytic hydrogenation/hydrogenolysis to give the fully deprotected title disaccharide fragment. Glycosylation of the (S)‐phosphate diol with 2,4‐di‐O‐benzyl‐3,6‐dideoxy‐α‐L‐xylo‐hexopyranosyl bromide under halide‐assisted conditions yielded a mixture of the tetrasaccharide and a trisaccharide, which were readily separable by chromatography. Their hydrogenation/hydrogenolysis effected global deprotection as well as reduction of the azide, to furnish the deprotected title tri‐ and tetrasaccharide.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Practice and theory of high temperature liquid chromatography
Authors: McNeff Clayton V. , Yan Bingwen , Stoll Dwight R. , Henry Richard A. 
Published: July 2007

AbstractHigh temperature liquid chromatography (HTLC) exists in a temperature region beyond ambient (ca. 40°C) and below super critical temperatures. The promises of HTLC, such as increased analysis speed, enhanced separation productivity, “green” LC with pure water mobile phases coupled to universal FID detection, and fast analysis of complex samples by combination with fast 2‐D techniques, have become an option for routine practice. The focus of this paper is to review the key developments that have made the application of HTLC a practical technique and draw attention to new developments in 2‐D techniques that incorporate HTLC that offer an opportunity to vastly increase the usefulness of HPLC for the analysis of complex samples.
Erratum: A quantitative approach to benefit‐risk assessment of medicines — part 2: the practical application of a new model
Authors: Mussen Filip , Salek Sam , Walker Stuart 
Published: July 2007

AbstractPharmacoepidemiology and Drug Safety 2007; 16: S16—S41; DOI: 10.1002/pds.1434It has come to the attention of the authors that this published article contained an error.The author Lawrence Phillips was mistakenly omitted from the original article. The full list of authors and affiliations can be seen below.Filip Mussen1,2, Sam Salek2, Stuart Walker3 and Lawrence Phillips41Regulatory Affairs Europe, Merck Sharp & Dohme (Europe), Inc., 5 Lynx Binnenhof, Brussels, B‐1200, Belgium2Centre for Socioeconomic Research, Welsh School of Pharmacy, Redwood Building, King Edward VII Avenue, Cardiff CF10 3XF, UK3CMR International, Novellus Court, 61 South Street, Epsom, Surrey, KT18 7PX, UK4Visiting Professor of Decision Sciences, Department of Management, Operational Research Group, London School of Economics, UKThe authors wish to apologise for any inconvenience caused.
Novel polymer monolith prepared from a water‐soluble crosslinking agent
Authors: Kubo Takuya , Kimura Naomi , Hosoya Ken , Kaya Kunimitsu 
Published: July 2007

AbstractIn this study, we described the fundamental properties of novel polymer monoliths that were prepared from a water‐soluble crosslinking agent. Each monolith was evaluated by scanning electron microscope (SEM) and scanning probe microscope (SPM) to observe the monolithic structure, and the polymer films that were prepared from several monomers were evaluated by the contact angle of water. As results of evaluations, the polymer prepared from a water‐soluble crosslinking agent had high hydrophilicity. Furthermore, SEM evaluations suggested that polymer porogenic solvent (PEG) was contributed to the construction of monolithic structure, and the polymerization degree of PEG was also taken effect of the structural changing by the variation of phase separation. Additionally, the results of SPM evaluations and the differences of monolithic structure were also reflected under water condition although the swelling of polymer was observed. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3811–3817, 2007
The breast cancer experience of rural women: a literature review
Authors: Ann Bettencourt B. , Schlegel Rebecca J. , Talley Amelia E. , Molix Lisa A. 
Published: July 2007

AbstractThis report is a review of studies that focus on rural breast cancer survivorship. It includes a total of 14 studies using large databases and 27 other studies using qualitative and quantitative methods. In our review of this literature, we identified four broad themes, including access to treatment and treatment type, medical providers and health information, psychosocial adjustment and coping, and social support and psychological support services. We review the findings of the rural breast cancer survivorship studies within each of these broad themes. A few of the findings of the review include that rural and urban women receive different primary treatments for breast cancer, that rural women may have greater difficulty negotiating their traditional gender roles during and after treatment, that rural women desire greater health‐related information about their breast cancer, and that rural women have less access to mental health therapy. The review discusses the implications of these findings as well as the weakness in the literature. Copyright © 2007 John Wiley & Sons, Ltd.