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Li G.,University of Shanghai for Science and Technology | Wang Z.,University of Shanghai for Science and Technology | Kubo A.,Research Institute for Applied science
Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science | Year: 2017

Accurately and rapidly evaluated error sensitivity of actual tooth surfaces of hypoid gears can be a significant foundation for a variety of dynamic preference analysis and machine tool setting readjustments. Due to the complexity of local geometric features as well as the limitations of the data measurement on tooth surfaces of hypoid gears, automated error-sensitivity analysis for actual tooth surfaces still presents many substantial challenges. This paper presents a novel methodology for the error-sensitivity analysis of real tooth surfaces of hypoid gears. The methodology combines an error-sensitivity analysis model with a numerical analytical real tooth contact analysis (RTCA) model. The real tooth surfaces, describing local micro-geometry features on actual tooth surfaces, have been produced by 3D discrete data points reconstruction. In this method, the discrete data points on actual tooth surfaces are measured by using a coordinate measure machine (CMM). The location, size, and shape of contact patterns are determined from the predicted interference areas distribution by numerical analysis. In addition, the error-sensitivity analysis model is established for evaluation of the sensitivity of hypoid gears with real tooth surfaces that corresponds to misalignments. The results of experiment show that the proposed method can obtain actual contact properties that significantly improve the basic design performances significantly. © Institution of Mechanical Engineers.


Osamura K.,Research Institute for Applied science | MacHiya S.,Daido University | Nishijima G.,Japan National Institute of Materials Science
Superconductor Science and Technology | Year: 2016

Practical REBCO and BSCCO-2223 tape-shaped wires are now manufactured on an industrial scale. They are a typical composite material consisting of superconducting layer/filaments together with functional components. These functional components affect directly the stress and strain dependences of the critical current. When applying an external stress R, the critical current I c was measured. Then the external stress was reduced to R = 0 and the recovered critical current I cr was again measured. The tensile stress and strain dependences of both normalized critical currents divided by the original value, I c/I c0 and I cr/I c0 were investigated. In general I cr/I c0 recovered close to unity when the applied stress was low, but its recovering level decreased gradually with increasing applied stress. The definition of the reversible stress and strain limits was investigated and its validity was proved using the cyclic loading test. The original definition of reversible stress and strain limits of critical current relates to: (1) when releasing the applied stress and strain, the I c shall recover to the original value, and (2) when applying the cyclic stresses, the I c shall keep the original value. Here, as a practical definition for the reversible stress and strain limits, the tensile stress and strain at 99% recovery of I c have been proposed. On the other hand, it was made clear that the stress and strain at I c 95% retention are not valid for use commonly as a criterion of reversible stress and strain limits for both practical REBCO and BSCCO-2223 wires. © 2016 IOP Publishing Ltd.


Ochiai S.,Kyoto University | Okuda H.,Kyoto University | Fujii N.,Kyoto University | Osamura K.,Research Institute for Applied science
Materials Transactions | Year: 2015

When high-temperature superconducting layer-coated conductors are exposed to high electromagnetic and/or mechanical stress and strain, the superconducting layer is damaged mainly by cracking. As cracking occurs heterogeneously, the critical current and n-value of a test specimen, which is composed of a series circuit of local sections, are dependent on the extent of cracking in local sections. In this work, the correlations of the extent of cracking in local sections with the critical current and n-value of the specimen were studied by modeling analysis. When one section is cracked, the critical current and n-value of the specimen decrease with increasing crack size. When multiple sections are cracked, the properties depend on the difference in crack size among the sections. When the crack size of the sections is similar, the critical current of the specimen decreases and the n-value increases as the number of cracked sections increases. This is caused by the increased voltage and the decreased shunting current at cracks. When there are large differences in the crack sizes of the sections, the section with the largest crack controls the voltage-current behavior of the specimen and determines the reduction in the critical current and n-value. For a given size of the largest crack, the critical current of the specimen is slightly higher and the n-value is lower when there is an intermediate difference in crack size among the sections than when there is a small difference in crack size, and the critical current is lower and the n-value is higher when there is an intermediate difference in crack size than when there is a large difference in crack size. © 2015 The Japan Institute of Metals and Materials.


Naruse H.,Kyoto University | Yamamoto O.,Research Institute for Applied science
Proceedings - International Symposium on Discharges and Electrical Insulation in Vacuum, ISDEIV | Year: 2014

This paper deals with a method to estimate the surface flashover voltage of an insulator in vacuum, in which the distribution of surface charge due to the Secondary Electron Emission Avalanche (SEEA) is taken into account. We show experimental and calculated results for cylindrical insulators made of glass ranging up to 50 mm in length. Since surface roughness of specimens affects the SEEA charge density, its influence on the flashover voltage is also examined. The calculation and experimental results have shown good agreement. For further confirmation of the applicability of our method, we have examined the flashover characteristic of a specimen when its surface consists of smooth and rough regions. © 2014 IEEE.


Kamei T.,Research Institute for Applied science
Sustainability | Year: 2012

The most important target of the concept "sustainability" is to achieve fairness between generations. Its expanding interpolation leads to achieve fairness within a generation. Thus, it is necessary to discuss the role of nuclear power from the viewpoint of this definition. The history of nuclear power has been the control of the nuclear fission reaction. Once this is obtained, then the economy of the system is required. On the other hand, it is also necessary to consider the internalization of the external diseconomy to avoid damage to human society caused by the economic activity itself, due to its limited capacity. An extreme example is waste. Thus, reducing radioactive waste resulting from nuclear power is essential. Nuclear non-proliferation must be guaranteed. Moreover, the FUKUSHIMA accident revealed that it is still not enough that human beings control nuclear reaction. Further, the most essential issue for sustaining use of one technology is human resources in manufacturing, operation, policy-making and education. Nuclear power will be able to satisfy the requirements of sustainability only when these subjects are addressed. The author will review recent activities of a thorium molten-salt reactor (MSR) as a cornerstone for a sustainable society and describe its objectives and forecasts. © 2012 by the authors.


Kubo A.,Research Institute for Applied science
Mechanisms and Machine Science | Year: 2016

It is obvious that the basics of gear technology is the theory of geometry for conjugate action of mating gears for transmission of motion through contacting tooth flanks. Teeth of actual gears though contact not only on tooth flank to tooth flank, but also at edges of tooth tip and of tooth sides. Such edge contact is usually out of the conjugate meshing theory of gearing. Many causes of failure of highly loaded gear teeth are initiated due to the contact at such tooth edges. Contact of tooth edge produces considerable amount of wear debris. Meshing teeth crush intruded wear debris and damage themselves. With run of gear operation, gear failure develops as a phenomenon of such a positive feedback system. © Springer International Publishing Switzerland 2016.


Osamura K.,Research Institute for Applied science
Nippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals | Year: 2016

Practical superconducting (SC) wires are typical composite material consisting of SC layer/filaments together with functional components. In the present article, the commonality among composite microstructures for five kinds of the practical SC wires available in the market was emphasized. Their mechanical characteristics and the stress/strain dependence of critical current have been compared in conjunction of the local strain exerted on the SC component. Finally activity of the international standardization relating to the superconductivity was introduced. © 2016 The Japan Institute of Metals and Materials.


Kamei T.,Research Institute for Applied science
Journal of Sustainable Development of Energy, Water and Environment Systems | Year: 2013

The largest two sectors emitting CO2 in the world are electricity generation and land-transportation. Therefore, nuclear power plays an important role in generating electricity with low CO2 emission. An important aspect needs to be considered to ensure environmental sustainability is nuclear non-proliferation and less amount of radioactive waste generated. Thus the use of “thorium” as nuclear fuel has received increasing interest because thorium produces little amount of plutonium and very little amount of long-lived minor actinide. However, thorium cannot be used immediately due to its lack of fissile isotope indispensable to start fission reaction. At the same time, electric vehicle and hybrid-vehicle become more popular as low-carbon automobiles. Rare-earth elements are indispensable for manufacturing these low-carbon automobiles. However the problem with rare-earth production is its radioactive by-product of “thorium”. Since the largest potential of consuming thorium by nuclear power still needs several decades for commercializing, there becomes a discrepancy in consumption and production of thorium causing unused stockpile of thorium. Several countries have announced to supply rare-earth but this cannot be safely and economically done unless thorium problem is solved. In this paper, an international framework called the “OREEC: Organization of Rare-Earth Exportation Countries” is proposed as a solution to this issue. The OREEC has mainly three functions: (1) ThAX, which is a financial collecting method, (2) Th FREE label, which is certification of adequate treatment of thorium and (3) The Bank, which stores separated thorium. © 2013, International Centre for Sustainable Development of Energy, Water and Environment Systems SDEWES. All rights reserved.


Nagae M.,Research Institute for Applied Science | Ise N.,Research Institute for Applied Science
Funtai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy | Year: 2016

The oxidation characteristics in air were investigated for Mo-Cr nitrides prepared by pulsed electric current sintering (PECS) of mixed Mo2N and CrN powder, in addition to their corrosion characteristics in boiling sulfuric acid. Mo2N type solid solutions were found to be easily formed using PECS. Sintered compacts with a CrN content of >35 wt% consisted of two kinds of solid solution: Mo2N type with a Cr:Mo atomic ratio of about 1:1, and a Cr-rich phase. The solid solubility limit for Cr in Mo2N was about 50 at%. The hardness of the sintered compacts decreased with increasing CrN content, and their density increased. Although Mo2N (0 wt% CrN) was strongly oxidized at temperatures above 773 K, sintered compacts with a CrN content of >35 wt% were highly resistant to oxidation even at temperatures above 1073 K. All of the sintered compacts except that containing 100 wt% CrN exhibited perfect corrosion resistance in boiling sulfuric acid (75 wt%).


Kubo A.,Research Institute for Applied science
Proceedings of the ASME Design Engineering Technical Conference | Year: 2011

Some typical examples of failure of gears made from very high strength steel are shown and its trigger and whose causes are discussed: Many of such failure are triggered by tooth side edge contact or tooth tip edge contact and meshing-in of the wear debris. The limit of validity of the traditional methods for load carrying capacity of gears exists in the fact that they are based on the theory of contact of tooth flanks that realize conjugate or almost conjugate action of gears. To be able to design reliable gears made from very high strength steel, a principle is shown that suggests a new method for tooth form modification and of longitudinal crowing modification to avoid such failure. Metallurgical problem of gear material and special heat treatment aiming high surface hardness is also discussed. Copyright © 2011 by ASME.

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