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排序方式: 共有122条查询结果,搜索用时 15 毫秒
1.
P. Ferdenzi C. Giaroli P. Mori C. Pedroni R. Piccinini R. Ricci O. Sala C. Veronesi F. Mineo 《The Science of the total environment》1994,150(1-3)
This communication deals with an aspect of occupational hygiene in a factory producing granite cutting diamond wheels by sintering, in moulds, of fine cobalt powder. The factory has been studied between 1988 and 1991; the Department of Preventive and Occupational Medicine of the Local Sanitary Unit of Reggio Emilia has followed the evolution of the local exhaust ventilation equipment supplied by the employer in that period. At the same time, the following measurements and observations were carried out: (a) cobalt exposure by personal sampling, (b) airborne cobalt measurements by area sampling, (c) biological monitoring of cobalt in urine, (d) health surveillance. 相似文献
2.
Diagnosis Criterion of Abnormality of Transformer Winding by Frequency Response Analysis (FRA) 下载免费PDF全文
SATORU MIYAZAKI YOSHINOBU MIZUTANI AKIRA TAGUCHI JUNICHI MURAKAMI NAOKAZU TSUJI MASAHIRO TAKASHIMA OSAMU KATO 《Electrical Engineering in Japan》2017,201(3):25-34
Frequency response analysis (FRA) is a powerful technique to detect internal abnormalities within power transformers. However, diagnosis criteria of power transformers by FRA have not been fully established yet. In this paper, a new evaluation method of degree of identification between two transfer functions is proposed. In the proposed method, a frequency window is employed and cross‐correlation factor is calculated with moving the window. Furthermore, the proposed method is applied to transfer functions of real transformers with or without some abnormalities. Based on this discussion, objective criteria for diagnosis of abnormalities of transformer windings by FRA are proposed. The proposed criteria are based on a few data of transformers with some abnormalities. Therefore, the proposed criteria are tentative and they would be improved by accumulation of further data. 相似文献
3.
YOTARO NOSE TAKAO TSUJI TSUTOMU OYAMA TAKAHARU ITO KATSUYA ABE MASAHIRO MINAMI KAZUNARI ISHIBASHI 《Electrical Engineering in Japan》2017,198(4):51-62
It is of prime importance to maintain voltage profile within the proper range in distribution systems with a large amount of photovoltaics and electric vehicles (EVs). In particular, there is a possibility that line drop compensation (LDC) logic, which is utilized for the control of load ratio tap transformer (LRT) does not work properly when reverse power flow is included partially. Hence, in this paper, we have developed a new LRT control method based on the sensor information supposing that some section switchgears with sensors are introduced in the future distribution systems. Specifically, the extreme value of voltage profile is estimated by convergence calculation in the section between the section switchgear with sensor and LRT. Moreover, the voltage at the end node can be estimated by LDC method using sensor information of section switchgear. The proposed method was tested using a distribution system model and its effectiveness was shown. 相似文献
4.
Mineo Nozaki Shengde Zhang Masao Sakane Kaoru Kobayashi 《Engineering Fracture Mechanics》2011,(8):1794-1807
This paper studies the creep–fatigue crack initiation and failure lives of Sn–3.5Ag solder notched specimens focused on the multiaxial strain at the notch root. Push–pull creep–fatigue tests were performed using three circumferential notched specimens using four kinds of creep–fatigue strain waveforms. Multiaxial strains at the notched section were calculated by finite element (FE) analysis under four kinds of creep–fatigue loading. Creep–fatigue damage laws were applied for evaluating the crack initiation and failure lives using the multiaxial strains obtained by the FE analysis. von Mises equivalent strain at the notch root estimated the crack initiation lives with a large scatter as well as the failure lives. Instead, the mean value of von Mises equivalent strain over the cross section of the notch root estimated the crack initiation and failure lives with a small scatter. 相似文献
5.
TSUJI Takao 《广东印刷》2009,(3):7-8
一、广色域印刷产生的背景是什么呢: 1.时代发展的需要 当前,利用数码相机进行原稿输入的普及,喷墨打印机的广泛使用,以及随着RGB数字工作流程体系的构筑,为了适应这佯的印刷环境,使得广色域的印刷开始并将得到广泛的应用. 相似文献
6.
The feasibility of a high speed zinc electrowinning cell using a Pt catalyzed hydrogen gas-diffusion electrode as an anode is investigated. This new type of zinc-winning cell is operated at a current density of 1.0 A cm–2, which is 20 times higher than usually employed in conventional methods. Current efficiency is 86% at 0.5 A cm–2 in an electrolyte containing 60 gl–1 Zn+270 gl–1 H2SO4, the zinc purity being at least 99.999%. The energy usage of the system is 1400 kWh and 380 m3 H2 gas per ton of zinc. 相似文献
7.
An easy and swift method to evaluate, in a system of interconnected earth electrodes, earth potentials on earthing systems of medium-voltage/low-voltage (MV/LV) substations, in an event of single-line-to-earth fault inside a high-voltage/medium- voltage (HV/MV) station, is presented. The advantage of the method is the simplicity of the mathematical model for solving complex systems of any size with a sufficient accuracy for practical purposes. This paper shows the results of simulations, performed on networks with different extensions and characteristics, organized in easy-to-read graphs and tables. A comparison of these results with the values obtained according to the procedure explained in the IEC-Standard 60909-3, and a study on the accuracy of the method has been made. Moreover, some considerations on the inclusion of earth electrodes of HV/MV stations within global earthing systems are done. 相似文献
8.
Nawalage F. Cooray Katsumi Kushiya Atsushi Fujimaki Ichiro Sugiyama Tadayuki Miura Daisuke Okumura Masao Sato Mineo Ooshita Osamu Yamase 《Solar Energy Materials & Solar Cells》1997,49(1-4)
In this study, two deposition methods (i.e. MOCVD and sputtering methods) to prepare n-type ZnO window layers for CIGS-based thin-film solar cells are discussed. In order to make ZnO : Al transparent conductive oxide (TCO) films prepared by DC magnetron sputtering comparable to ZnO : B TCO prepared by MOCVD, a new ZnO sputtering process is proposed by introducing a multilayer structure. Using these films, CIGS thin-film solar cells with efficiencies of greater than 14% have been fabricated with an active area of 3.2 cm2. This structure was adapted to fabricate CIGS thin-film mini-modules with efficiencies around 11% having aperture area of 50 cm2. 相似文献
9.
The concentrations of quenched-in vacancies retained in B2 intermetallic compound Fe1-cAlc were obtained as functions of composition (0.39 < c < 0.51) and quenching temperature (773–1273 K) from lattice constant and density measurements. Obtained vacancy concentration indicates rather gradual increase with composition in lower Al content region, while it increased rapidly as the composition approaches to stoichiometric composition. Further, the data for slow-cooled (1 K min−1) samples showed that retained vacancy concentration is higher than that for samples annealed at and quenched from 773 K. Observed lattice constant for each composition decreases linearly with vacancy concentration, which is interpreted in terms of atomic size effect. From changes in vacancy concentration with quenching temperature, apparent vacancy formation energies were estimated. The relation between vacancy concentration and microhardness was also examined. Present results of dependency of lattice constant on heat treatment condition confirm the hardening effect due to retained vacancy. Further, the proposed linear relation of hardness to the square root of vacancy concentration is supported by the present study. 相似文献
10.
Shijie Zhu Yutaka Kagawa Jian-Wu Cao Mineo Mizuno 《Metallurgical and Materials Transactions A》2004,35(9):2853-2859
Time-dependent deformation in an enhanced SiC/SiC composite has been studied under constant load at high temperatures of 1200
°C, 1300 °C, and 1400 °C. Creep damage evolution was evaluated by a Young’s-modulus change of partial unloading and microscopic
observation. The addition of the glassy phase in the matrix is very effective for protecting the composite from oxidation.
The transient creep is dominant in creep life at all the temperatures. An empirical equation is proposed to describe creep
behavior of the composite. It is found that creep activation energy increases with creep time at stresses lower than matrix
cracking stress, but the activation energy remains constant at stresses higher than the matrix cracking stress. The creep
strain rate of the composite is considered to be controlled by creep of fibers based on examining the time, strain, stress,
and temperature dependencies of creep strain rates. 相似文献