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Detection of Fracture in Steel Members of Building Structures by Microstrain Measurement
Jun Iyama 한국강구조학회 2020 International Journal of Steel Structures Vol.20 No.5
This paper discusses a possibility of detecting structural damage caused by an earthquake, by measuring the time history of the strain of beams and columns before and/or after the earthquake. An index called “local stiffness” is defined as the ratio of section force amplitude to representative displacement amplitude, and this ratio can be physically interpreted as stiffness. By calculating section force amplitude at a section or node from the measured strain amplitude under a microtremor or small aftershocks and comparing it with the results of a static pushover analysis, it becomes possible to detect any structural damage, such as fractures. This methodology was applied and the microstrain data of a steel moment frame were measured in a large-scale shaking table test; beam-end fractures were observed after some excitation tests. After the beam-end fracture formed, the measured local stiffness dropped significantly below the analysis value, indicating the possibility of employing this value to detect fractures using the analysis value as a threshold value.
Kazutoshi Sakakibara,Muneyoshi Iyama,Ikuko Nishikawa 제어로봇시스템학회 2009 제어로봇시스템학회 국제학술대회 논문집 Vol.2009 No.8
In this paper, we consider a class of pickup and delivery problems. The problem requires that any paired pickup and delivery locations have to be served by one vehicle and the pickup location has to be scheduled before the corresponding delivery location in the route. In order to find near-optimal transportation plans, we discuss a hybrid approach mixing branch-and bound techniques and meta-heuristics. The key idea is that an original problem is decomposed into a set of sub-problems, in which the number of customers assigned to each vehicle is fixed, and respective sub-problem is solved by meta-heuristics such as simulated annealing heuristics. Then, promising sub-problems are able to be found efficiently by using branch-and-bound techniques. The effectiveness and the potential of the proposed approach are evaluated by a series of computational experiments.
Beard, B.B.,Kainz, W.,Onishi, T.,Iyama, T.,Watanabe, S.,Fujiwara, O.,Wang, Jianqing,Bit-Babik, G.,Faraone, A.,Wiart, J.,Christ, A.,Kuster, N.,Lee, Ae-Kyoung,Kroeze, H.,Siegbahn, M.,Keshvari, J.,Abrish [Institute of Electrical and Electronics Engineers 2006 IEEE transactions on electromagnetic compatibility Vol.48 No.2
The specific absorption rates (SAR) determined computationally in the specific anthropomorphic mannequin (SAM) and anatomically correct models of the human head when exposed to a mobile phone model are compared as part of a study organized by IEEE Standards Coordinating Committee 34, Sub-Committee 2, and Working Group 2, and carried out by an international task force comprising 14 government, academic, and industrial research institutions. The detailed study protocol defined the computational head and mobile phone models. The participants used different finite-difference time-domain software and independently positioned the mobile phone and head models in accordance with the protocol. The results show that when the pinna SAR is calculated separately from the head SAR, SAM produced a higher SAR in the head than the anatomically correct head models. Also the larger (adult) head produced a statistically significant higher peak SAR for both the 1- and 10-g averages than did the smaller (child) head for all conditions of frequency and position.
Satoshi Yamada,Yuko Shimada,Takanori Ishida,Yuka Matsumoto,Jun Iyama,Hiroumi Shimokawa,Hiroshi Ito,Satoshi Aoyagi 한국강구조학회 2020 International Journal of Steel Structures Vol.20 No.5
Submerged arc welding, which is generally used for the corner joint of box-section columns, is a welding process with a high heat input. The influence on the strength and toughness of the heat-affected zone is an important concern, especially when used with a high-performance steel that may be more susceptible to heat input. The ductility of the welded corner joint is one of the important factors to ensure safety against external forces, such as during severe earthquakes. In this study, a series of material and cyclic loading tests of the corner joint comprising SA440C high-performance steel fabricated by submerged arc welding were conducted. The experimental results indicated that the welded corner joint comprising SA440C steel is ductile enough to dissipate input energy caused by the strong ground motion from an earthquake.
Naohiro Nishikawa,Katsuhiko Omoe,Kenji Murakami,Yusuke Sato,Takekazu Sawa,Yoshihiro Hagihara,Nobuhito Yoshihara,Hiroaki Okawai,Toshirou Iyama,Masahiro Mizuno,Shinya Tsukamoto 한국정밀공학회 2013 International Journal of Precision Engineering and Vol. No.
It is great concern that is environmental load in manufacturing. In machining site, metal working fluid (coolant) such as cutting oil,grinding fluid is used. It contains several chemicals that are oil, surface active agent, extreme pressure additive, antirust agent,antifoaming agent, preservative, biocide etc.. It is thought that it is not good for environment and human body. Machining fluid mist and splash contained several chemicals that are cause of danger for worker’s health while machining. Furthermore, time elapses, fluid is rotten by bacteria. Bad smell and degradation of machining performance occurs. Therefore, after using machining fluid, waste fluid is disposed. Incineration or coagulative precipitation and landfill etc. are necessary. It arise great disposal cost and environmental load as discharging of huge amount green house gas (CO2 etc.). Then, machining fluid decreasing or non-using is demanded in industry. So, in this investigation, new environmental machining method: the electric rust preventive machining method system that uses only water as machining fluid has been developed. In this paper, water purification recycle system in water machining system development is mentioned. Therefore, complete removal of bacteria (Enterobacter aerogenes) without using chemicals such as biocide is examined for corruption, malodor prevention and safe machining water.