bluuebunny/crossref_metadata_2025_split huggingface dataset:
Operation of superconducting fault current limiter using vacuum interrupter driven by electromagnetic repulsion force for commutating switch
Authors: Shimizu Iwao , Naito Yuji , Yamaguchi Iwao , Kaiho Katsuyuki , Mizoguchi Hitoshi , Yanabu Satoru 
Published: April 2008

AbstractUsing conventional high‐temperature superconducting wire, a model superconducting fault current limiter (SFCL) is made and tested. Solenoid coil using Bi2223 silver sheath wire is so made that inductance is as small as possible and a vacuum interrupter is connected in series to it. A conventional reactor coil is connected in parallel. When the fault current flows in this equipment, superconducting wire is quenched and current is transferred into the parallel coil because of voltage drop of superconducting wire. This large current in parallel coil actuates magnetic repulsion mechanism of vacuum interrupter. Due to opening of vacuum interrupter, the current in superconducting wire is broken. By using this equipment, current flow time in superconducting wire can be easily minimized. On the other hand, the fault current is also easily limited by large reactance of parallel coil. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 164(1): 52–61, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20315
Influence of system operation method on CO2 emissions of PV/solar heat/cogeneration system
Authors: Oke Shinichiro , Kemmoku Yoshishige , Takikawa Hirofumi , Sakakibara Tateki 
Published: April 2008

AbstractA PV/solar heat/cogeneration system is assumed to be installed in a hotel. The system is operated with various operation methods: CO2 minimum operation, fees minimum operation, seasonal operation, daytime operation, and heat demand following operation. Of these five operations, the former two are virtual operations that are operated with the dynamic programming method, and the latter three are actual operations. Computer simulation is implemented using hourly data of solar radiation intensity, atmospheric temperature, electric, cooling, heating, and hot water supply demands for one year, and the life‐cycle CO2 emission and the total cost are calculated for every operation. The calculation results show that the two virtual and the three actual operations reduce the life‐cycle CO2 emission by 21% and 13% compared with the conventional system, respectively. In regard to both the CO2 emission and the cost, there is no significant difference between the two virtual operation methods or among the three actual operation methods. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 164(2): 54–63, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20414
Rotor resistance identification and stability control method in bearingless induction motor drives
Authors: Akamatsu Daigo , Orita Shuichi , Chiba Akira , Fukao Tadashi 
Published: April 2008

AbstractGenerally, vector controllers in induction motors tend to suffer from the influence of rotor resistance variation caused by temperature and load torque conditions. Several rotor resistance identification methods have been proposed in the literature. In this paper, a novel rotor resistance identification technique is proposed based on variables in the magnetic suspension control loops. When static force, such as a shaft weight, is applied, force commands are automatically generated in the opposite direction to satisfy the force equilibrium. However, the amplitude and direction of the force command vary in accordance with the rotor resistance variation. Thus, the rotor resistance can be identified from the suspension force command. In addition, influence of temperature drift in gap sensors is investigated. The effectiveness is confirmed experimentally. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 164(1): 86–97, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20423
An investigation of induced voltages to an underground gas pipeline from an overhead transmission line
Authors: Isogai Hiroshi , Ametani Akihiro , Hosokawa Yuji 
Published: April 2008

AbstractThis paper investigates induced voltage characteristics from an overhead transmission line by applying a method of modeling of induced voltages proposed by the authors. EMTP simulation results obtained by the modeling method agree with analytical results obtained from a well‐known formula. The induced voltages are significantly dependent on the configuration of the overhead line. A horizontal line induces the largest voltage in a gas pipeline, and the voltage induced by a vertical twin‐circuit line is about 20% smaller than that induced by a vertical single‐circuit line. The method is applied to a real pipeline system and the simulation results show reasonable agreement with field test results. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 164(1): 43–51, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20465
A distributed autonomous approach for bulk power system restoration by means of multi‐agent system
Authors: Nagata Takeshi , Tahara Yoshiki , Kunisa Daisuke , Fujita Hideki 
Published: April 2008

AbstractIn recent years, the electric utility industry worldwide has been facing pressure to be deregulated. Also, the risk of blackout in large areas will increase. Actually, it is still vivid in our memory that the northeastern United States and southern Canada suffered the worst blackout in history. Consequently, a method to find the optimal solution rapidly is needed all the more. In this paper, we propose a new multi‐agent method for a bulk power system restoration. In order to demonstrate the capability of the proposed multi‐agent system, it has been applied to a model bulk power system, which consists of three local areas including 12 generating units and 12 loads, and three remote areas with 12 loads. A large number of simulations are carried out on this model network with changing conditions. The simulation results show that the proposed multi‐agent approach is effective and promising. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 164(1): 69–76, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20485
Development of Y‐branch joint for 275‐kV XLPE and fluid‐filled cable
Authors: Goto Takeshi , Yamashita Makoto , Sakamaki Masatoshi 
Published: April 2008

AbstractWhen a new UHV substation is built in an urban region, generally, an existing underground transmission line will be diverted and drawn into the new substation. Compared with the latter construction method, enormous cost reduction of switching facilities and cable construction is expected when applying a Y‐branch joint (YJ) which is able to serve as a three‐way joint. The YJ has already been applied for 154‐kV‐class circuit, but it has not been investigated for 275‐kV‐class circuit. Since both XLPE and oil‐filled cable are presently used in 275‐kV‐class underground cable line, a universal design YJ for both cables has been investigated. The YJ was applied in a compact design which was based on our sophisticated electrical stress control technology for 500‐kV prefabricated‐type joint. Furthermore, the design was based on its prefabricated assembling technology. The YJ was verified as to its electrical and mechanical performance as 275‐kV cable joint by completion of its assembling test and a long‐term electrical test. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 164(2): 18–24, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20514
An adaptive and reliable system based on interdependence between agents
Authors: Tanimoto Akifumi , Matsumoto Keinosuke , Mori Naoki 
Published: April 2008

AbstractA multiagent system (MAS) has recently gained public attention as a technique to solve competition and cooperation in distributed systems. However, MAS's vulnerability due to the propagation of failures prevents its application to a large‐scale system. This paper proposes a general composition technique to improve its reliability easily applied to the existent MAS. The proposed system monitors messages between agents to detect undesirable behaviors (failures). Collecting related information, the system generates global information of interdependence between agents and expresses it in a graph. This interdependence graph enables us to detect or predict undesirable behaviors. This paper also shows that the system can optimize performance of MAS and improve adaptively its reliability under complicated and dynamic environment by applying the global information acquired from analysis of the interdependence graph to a replication system. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 164(1): 62–68, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20517
Cooperative allocation of SVR and SVC for voltage fluctuation in case of connecting distributed generators
Authors: Sugimoto Junjiro , Yokoyama Ryuichi , Fujita Goro , Fukuyama Yoshikazu 
Published: April 2008

AbstractThis paper presents a method for cooperative allocation of step voltage regulators (SVRs) and static var compensators (SVCs) when some distributed generators (DGs) are installed in a distribution system. In the proposed method, reactive tabu search (RTS) with multiple structures and functions is applied. First, the allocations of the SVRs are selected optimally and then the tap positions of the SVRs are optimized by the RTS. Finally, the locations of the SVC are chosen in order to enhance the voltage profile in the distribution network. The proposed method enables us to take account of the installation cost of both SVRs and SVCs as an economic criterion, of the upper and lower voltage limit at each node, and also of the upper limit of line currents as constraints. By applying the proposed method to a practical distribution test system (IEEE 34 Node Test Feeder Model), it is verified that this method is efficient in allocating SVRs and SVCs at minimum cost and in regulating the system voltages within an appropriate range after introducing DGs into the distribution system. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 164(2): 10–17, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20639
A DC micro‐grid for superhigh‐quality electric power distribution
Authors: Kakigano Hiroaki , Miura Yushi , Ise Toshifumi , Uchida Ryohei 
Published: April 2008

AbstractThe “DC Micro‐grid” is a novel power system using DC distribution in order to provide superhigh‐quality electric power. The DC distribution system is suitable for DC output distributed generation techniques such as photovoltaic and fuel cells, and energy storage forms such as batteries and electric double‐layer capacitors. The power is distributed through a DC distribution line and converted to the required AC or DC voltage by converters placed near loads. The load‐side converters do not need transformers due to the choice of the proper distributed DC voltage. The spread converter scheme helps to assure high‐quality power supply. Even if a short circuit occurs on one load side, it does not affect other loads. In this paper, we propose a DC micro‐grid configuration and converter control methods for generation and energy storage. Computer simulation results demonstrate seamless operation during turn‐on and turn‐off of distributed generation, transients at the times of connecting and disconnecting operation with the bulk power system, and stability against sudden large load variations. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 164(1): 34–42, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20641
Detection of weak radiation involving generation and progress of water tree
Authors: Kumazawa Takao , Taniguchi Ryouichi 
Published: April 2008

AbstractIt is well known that generation and progress of water trees in XLPE cables are strongly enhanced by inorganic impurities. We have investigated the effect of such impurities in the water treeing process and reported the experimental results as follows: (1) the anomalous increase or decrease in several kinds of inorganic elements was observed in water treed XLPE samples, (2) a distinctive relationship was found for the mass numbers for the elements, and (3) the isotopic content of the elements such as Zn deviated over 6% from the naturally occurring level. These results suggest that some unknown phenomena play a role in the formation of water trees, such as cold fusion or nuclear transmutation in condensed matter. In order to study the relationship between water trees and these phenomena, we attempted to detect neutrons, γ‐rays, or X‐rays accompanying the generation and progress of water trees in XLPE samples. In the experiments, weak and burst‐like radiation, apparently low‐energy γ‐rays or X‐rays, was often detected by BF3 and/or CdZnTe counter. The radiation tended to be detected in the samples with a large number of water trees generated by supplying sufficient amounts of inorganic cations. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 164(2): 1–9, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20672
A tower model for lightning overvoltage studies based on the result of an FDTD simulation
Authors: Noda Taku 
Published: April 2008

AbstractThis paper describes a method for deriving a transmission tower model for EMTP lightning overvoltage studies from a numerical electromagnetic field simulation result obtained by the FDTD (Finite Difference Time Domain) method. The FDTD simulations carried out in this paper take into account the following items which have been ignored or oversimplified in previously presented simulations: (i) resistivity of the ground soil; (ii) arms, major slant elements, and foundations of the tower; (iii) development speed of the lightning return stroke. For validation purpose a pulse test of a 500‐kV transmission tower is simulated, and a comparison with the measured result shows that the present FDTD simulation gives a sufficiently accurate result. Using this validated FDTD‐based simulation method the insulator‐string voltages of a tower for lightning strokes are calculated, and based on the simulation result the parameter values of the proposed tower model for EMTP studies are determined in a systematic way. Since previously presented models include trial‐and‐error process in the parameter determination, it can be said that the proposed model is more general in this regard. As an illustrative example, the 500‐kV transmission tower mentioned above is modeled, and it is shown that the derived model closely reproduces the FDTD simulation result. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 164(1): 8–20, 2008; Published online in Wiley InterScience (www.interscience. wiley.com). DOI 10.1002/eej.20675
Assessment of detachment and sediment transport capacity of runoff by field experiments on a silt loam soil
Authors: Schiettecatte W. , Verbist K. , Gabriels D. 
Published: April 2008

AbstractThe detachment capacity (Dc) and transport capacity (Tc) of overland flow are important variables in the assessment of soil erosion. They determine respectively the lower and upper limit of sediment transport by runoff and therefore control detachment and deposition pro‐cesses. In this study, the detachment and transport capacity of runoff was investigated by rainfall simulations and overland flow experiments on small field plots. On the bare field plots, it was found that Tc was strongly related to total runoff discharge. This was also observed for the plots covered by maize residues, but Tc was less due to the lower runoff velocity. A simple regression equation was derived to estimate Tc for both bare and covered soil. Comparing our observations with Tc equations mentioned in the literature revealed that Tc equations based on laboratory experiments overestimated, on average, our measurements. Although Tc can be assessed more easily in laboratory experiments, the applicability of the results to field conditions remains questionable. Detachment by runoff was also related to total runoff discharge. The Dc values were, however, 4–50 times smaller than the Tc at corresponding high and low runoff discharge. This indicates that detachment by runoff constitutes only part of the transported sediment. Interrill erosion supplies an important additional amount of sediment. In this study, however, only sealed soils were considered. In the case of freshly tilled, loose soils, the Dc of runoff may be larger, resulting in a larger contribution to the total soil loss. Copyright © 2008 John Wiley & Sons, Ltd.
A new sampler for extracting bed material sediment from sand and gravel beds in navigable rivers
Authors: Singer Michael Bliss 
Published: April 2008

AbstractGrain‐size distributions of bed material sediment in large alluvial rivers are required in various scientific and management applications, but characterizing gravel beds in navigable rivers is hampered by difficulties in sediment extraction. The newly developed and preliminarily tested sampler reported here can extract sediment from a range of riverbeds. The 36 × 23 × 28 cm stainless steel toothed sampler is deployed from and dragged downstream by the weight of a jet boat, and it improves upon previous samplers that are unable to penetrate gravel bed surfaces, have small apertures, and/or cannot retain fine sediment. The presented sampler was used to extract 167 bed material sediment samples of up to 16 kg (dry weight) with an average sample size of ∼6 kg from 67 cross‐sections spanning 160 river kilometres along the Sacramento River. It was also tested at three sites on a subaerial bar to compare surface, subsurface, and sampler distributions. Sampler penetration is ∼5 cm. The device collects individual samples that satisfy the criterion for bed material sediment whereby the largest particle comprises no more than 5% of the total sample mass in gravel and sand beds, except where the degree of surface armouring is large (e.g. armor ratios >> 2) and where more than 10% of bed material sediment is composed of grains larger than 64 mm. When aggregated samples exceed 15 kg, all satisfy the criterion whereby the largest particle comprises no more than 1% of the total sample mass. Samples closely resemble surface size distributions, except where armouring is strong. The sampler should be subject to more rigorous field testing, but many of its current limitations are expected to become negligible with the advent a larger, heavier version of the sampling device. Copyright © 2008 John Wiley & Sons, Ltd.
Adaptive radio resource management in an integrated GPRS/UMTS service network
Authors: Chen Jiann‐Liang , Pan Shih‐Wei , Chen Ming‐Chiao , Huang Yueh‐Min 
Published: April 2008

AbstractToday's 2G/2.5G systems are designed to achieve 90‐‐95 per cent coverage. Most operators plan to construct 3G base stations on previous 2G/2.5G stations. Consequently, integrated radio resource management (RRM) is comprised of timeslot‐limited and interference‐limited systems. To improve capacity, this study presents a novel resource management based on timeslot utilisation in an integrated general packet radio service/universal mobile telecommunications systems (GPRS/UMTS) service network. Although this approach gives UMTS high priority for sending data services, it also makes voice services available over general system for mobile communications (GSM). Experiments are performed to analyse the system performance, and indicate two observations. (1) The proportion of data sessions that obtain the required bandwidth is 90 per cent, and the average loss ratio is 1 per cent; the average delay time is qualified to support real‐time services, except for data services in GSM/GPRS. (2) For a heavy load, UMTS and GPRS share the traffic loads efficiently, so the increase in the integrated system capacity is 7.14 per cent and 13.33 per cent for the 64 and 128 kbps data services, respectively. Copyright © 2008 John Wiley & Sons, Ltd.
Genetic association tests in the presence of epistasis or gene‐environment interaction
Authors: Wang Kai 
Published: April 2008

AbstractA genetic variant is very likely to manifest its effect on disease through its main effect as well as through its interaction with other genetic variants or environmental factors. Power to detect genetic variants can be greatly improved by modeling their main effects and their interaction effects through a common set of parameters or “generalized association parameters” (Chatterjee et al. [2006] Am. J. Hum. Genet. 79:1002–1016) because of the reduced number of degrees of freedom. Following this idea, I propose two models that extend the work by Chatterjee and colleagues. Particularly, I consider not only the case of relatively weak interaction effect compared to the main effect but also the case of relatively weak main effect. This latter case is perhaps more relevant to genetic association studies. The proposed methods are invariant to the choice of the allele for scoring genotypes or the choice of the reference genotype score. For each model, the asymptotic distribution of the likelihood ratio statistic is derived. Simulation studies suggest that the proposed methods are more powerful than existing ones under certain circumstances. Genet. Epidemiol. 2008. © 2008 Wiley‐Liss, Inc.
The impact of using different imputation methods for missing quality of life scores on the estimation of the cost‐effectiveness of lung‐volume‐reduction surgery
Authors: Blough David K. , Ramsey Scott , Sullivan Sean D. , Yusen Roger 
Published: April 2008

AbstractA post hoc analysis of data from a prospective cost‐effectiveness analysis (CEA) conducted alongside a randomized controlled trial (National Emphysema Treatment Trial – NETT) was used to assess the impact of using different imputation methods for missing quality of life data on the estimation of the incremental cost‐effectiveness ratio (ICER). The NETT compared lung‐volume‐reduction surgery plus medical therapy with medical therapy alone in patients with severe chronic obstructive pulmonary disease due to emphysema. One thousand sixty‐six patients were followed for up to 3 years after randomization. The cost per quality‐adjusted life‐year gained was obtained, computing costs from a societal perspective and using the self‐administered Quality of Well Being questionnaire to measure quality of life. Different methods of imputation resulted in substantial differences in ICERs as well as differences in estimates of the uncertainty in the point estimates as reflected in the CEA acceptability curves. Paradoxically, the use of a conservative single imputation method resulted in relatively less uncertainty (anticonservative) about the ICER. Owing to the effects of different imputation methods for missing quality of life data on the estimation of the ICER, we recommend use of a minimum of two imputation methods that always include multiple imputation. Copyright © 2008 John Wiley & Sons, Ltd.