Papers by Keyword: Lifetime

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Authors: Sebastien Bertrand, O. Boisron, R. Pailler, Jacques Lamon, Roger R. Naslain
Authors: Annett Schmieder, Thorsten Heinze, Markus Michael
Abstract: Until the present days, in discontinuous conveyor systems, e.g. cranes and elevators, steel wire ropes and steel chains are the exclusively used tension members. Nevertheless, these tension members are exhibiting essential disadvantages, e.g. high dead weight, low bending flexure and high susceptibility to corrosion. For fulfilling the steadily increasing requirements especially in running ropes, alternative tension members have to be developed and approved concerning their series-production readiness by utilization of new technologies and new materials. High-strength fiber ropes are demonstrating promising mechanical properties, regarding tensile strength, vibration behavior and bending fatigue life. Still, the application of such high-strength fiber ropes is limited, due to unavailable systematic investigations and insufficient guidelines for dimensioning and processes for determination of discard criteria. With the help of new technologies and procedures, e.g. multi-zone cyclic bend-over-sheave (CBOS) test machinery and computer-assisted tomography, new knowledge concerning the wear behavior of fiber ropes is to be gained and new discard criteria are to be developed.
Authors: Wei Qi Li, Jun Hong, Yun Long Li, Yi Zhang, Zong Bin Li
Abstract: Product tolerance is one of the important factors which affect the quality and cost of product. However, influenced by many complicated factors, there are still many problems which need to be resolved compared with other research works in CAD field. How to determine tolerances of product effectively is still a big problem. Based on exponent model of tolerance-cost, the relationships between tolerance and other characteristics influencing processing cost are studied in this paper. A relational model of tolerance-cost is come up with based on the above relationships. And then, internal relation between tolerance and lifetime is discussed. Meanwhile, along with the lifetime converted into the cost, the compensated relational model of tolerance-lifetime is presented. Finally, the method on the decision of tolerance grade is analyzed. This paper realizes the organic combination of tolerance, lifetime and cost, and effectively decides how to generate tolerance grades.
Authors: F. Lamouroux, Sebastien Bertrand, R. Pailler, Roger R. Naslain
Authors: Wen Hao Li, Shao Chuan Wu, Liang Ye, Shuo Shi
Abstract: Wireless sensor networks are widely deployed in various areas of our daily life. The lifetime of wireless sensor networks takes significant effect in the performance of the whole network. Many network protocols are proposed to improve the lifetime of networks, and among them, low-energy adaptive clustering hierarchy (LEACH) is a promising protocol with self-organization of the clusters and periodic rotation of cluster heads selection to distribute energy consumption uniformly. LEACH performs well compared with other protocols on lifetime while it is simplified and has aspects to improve. In this paper, we modified the procedure of cluster heads selection in LEACH and proposed a protocol LEACH-CHE with consideration on the energy consumption of cluster heads. We analyzed LEACH-CHE and with the results of simulations, LEACH-CHE over performs on network lifetime compared with the original LEACH.
Authors: Shi Bin Song, Qi Song, Xiao Jun Xue, Yun Wan
Abstract: With the coming rush of population aging and the termination of the demographic dividend, the question on the extension of the legal retirement age is becoming a hot topic in the community. This paper analyzes factors affecting retirement age,such as demographic dividend, life expectancy, years of education per capita, supply and demand situation in labor market. From these factors, reasonable quantitative reference standards can be introduced.
Authors: Hidekazu Tsuchida, Isaho Kamata, Masahiko Ito, Tetsuya Miyazawa, Hideyuki Uehigashi, Keisuke Fukada, Hiroaki Fujibayashi, Masami Naitou, Kazukuni Hara, Hitoshi Osawa, Toshikazu Sugiura, Takahiro Kozawa
Abstract: This paper reports on recent advances in 4H-SiC epitaxial growth toward high-throughput production of high-quality and uniform 150 mm-diameter 4H-SiC epilayers by enhancing of growth rates, improving uniformity and reducing defect densities. A vertical single-wafer type SiC epitaxial reactor is employed and high-speed wafer rotation is confirmed as effective, not only for enhancing growth rates without increasing the source gas supply but also improving thickness and doping uniformities. The current levels of reducing particle-induced defects, in-grown stacking faults, basal plane dislocations and the Z1/2 center (carbon vacancies) are reviewed.
Authors: M. Koch, Karin Maier, J. Major, Alfred Seeger, J.P.F. Sellschop, E. Sideras-Haddad, H. Stoll, S.H. Connell
Authors: Noella Evano, Rochdi El Abdi, Marcel Poulain
Abstract: During their use, optical fibers are subject to harsh installation and environmental conditions. To evaluate more precisely the lifetime of an optical fiber, it is necessary to study the mechanical behavior of optical fibers under extreme conditions, in particular under mechanical and thermal stress.This paper presents the results of new silica optical fibers aged in hot water between 20°C and 70°C and subjected to mechanical static bending stresses from 3 GPa to 3.5 GPa. Thermal dependence of the time to failure was observed. This dependence can be described by the Arrhenius model, where the activation energy is one of the main physical characteristic.
Authors: Oleg S. Kachin, Alexander S. Karakulov, Alexander B. Serov
Abstract: The mathematical description of the wear processes of brushes of brush-type motors is described. The actions directed on increase of the lifetime of brushes are offered. The proposed mathematical model of the wear processes of brushes considers the highest number of parameters of a sliding contact, including sparking energy of windings switching and the mechanical condition of a commutator and bearings. The approach for evaluating the optimum pressure on the brush in order to increase its resource is offered. The real and the virtual lifetime tests of the universal motor considering changing of the mechanical state of the commutator and bearings during lifetime were carried-out. The constant force value acting on the brush which provides its lifetime increase by 11% is proposed.
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