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991.
G. LABEAS T. H. KERMANIDIS 《Fatigue & Fracture of Engineering Materials & Structures》2003,26(5):449-457
ABSTRACT Research results concerning the simulation of the crushing behaviour of composite systems with energy absorption characteristics are presented in the present work. The study is focused on the ‘tensor skin’ concept, an energy absorbing composite system that was originally developed to improve the crashworthiness of helicopters under water impact and which is promising for utilization in the construction of the lower part of composite fuselage aircraft. The ‘tensor skin’ concept comprises a folded or corrugated composite construction, which upon loading unfolds by forming ‘plastic hinges’, leading to an increase in the load bearing capability of the structure. The numerical modelling issues and the critical aspects of the simulation are discussed. Verification of the numerical simulation procedure is performed by experimental work. The experimental results utilized to assess and validate the numerical procedure were derived within the European Research Project ‘Design for Crash Survivability – CRASURV’ (BRITE – Aeronautics Area). The results of the simulations are generally in good agreement with experimental data. 相似文献
992.
O. T. Tsyrul’nyk H. M. Nykyforchyn D. Yu. Petryna M. I. Hredil’ I. M. Dz’oba 《Materials Science》2007,43(5):708-717
We study the degradation of the mechanical and corrosion properties of 17G1S steel in gas mains as a result of operation for
28–40 yr. We reveal the simultaneous decrease in its strength and hardness, on the one hand, and impact toughness and crack
resistance, on the other hand. The indicated parameters prove to be most sensitive to the in-service degradation of the metal.
The degradation of steel leads to the increase in the strain-hardening coefficient and the appearance of the yield plateau
in the tensile stress-strain diagram and causes the appearance of sensitivity to hydrogen embrittlement increasing in the
process of operation. We analyze the role of absorbed hydrogen affecting the mechanism of strain aging and responsible for
the appearance of defects. It is shown that the polarization resistance can be used not only for monitoring of the corrosion
state of gas pipelines but also for the prediction of changes in their mechanical properties in the process of operation.
__________
Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 43, No. 5, pp. 97–104, September–October, 2007. 相似文献
993.
Iida M. Kuroda N. Otsuka H. Hirose M. Yamasaki Y. Ohta K. Shimakawa K. Nakabayashi T. Yamauchi H. Sano T. Gyohten T. Maruta M. Yamazaki A. Morishita F. Dosaka K. Takeuchi M. Arimoto K. 《Solid-State Circuits, IEEE Journal of》2005,40(11):2296-2304
A 16 Mb embedded DRAM macro in a fully CMOS logic compatible 90 nm process with a low noise core architecture and a high-accuracy post-fabrication tuning scheme has been developed. Based on the proposed techniques, 61% improvement of the sensing accuracy is realized. Even with the smallest 5 fF/cell capacitance, a 322 MHz random-cycle access while 32 ms data retention time which contributes to save the data retention power down to 60 /spl mu/W are achieved. 相似文献
994.
A revision algorithm is a learning algorithm that identifies the target concept, starting from an initial concept. Such an algorithm is considered efficient if its complexity (in terms of the resource one is interested in) is polynomial in the syntactic distance between the initial and the target concept, but only polylogarithmic in the number of variables in the universe. We give an efficient revision algorithm in the model of learning with equivalence and membership queries for threshold functions, and some negative results showing, for instance, that threshold functions cannot be revised efficiently from either type of query alone. The algorithms work in a general revision model where both deletion and addition type revision operators are allowed. 相似文献
995.
An advanced learning system for interactive simulation of patient cases (ISP) is described. The system was designed to meet specific pedagogical needs where student activation and problem orientation were two of the key issues. The system includes features such as video based illness history-taking function using free text input, highly interactive physiological examination procedures, extensive laboratory tests and detailed user feedback. The system was constructed mainly in Authorware Professional, starting more than 10 years ago, and it is now available in refined versions in different languages. Twelve pedagogical and three technical features were initially defined for the project. All of these aims were fulfilled. The ISP system has been successfully used in education, and in international collaboration, including three applicability field tests. The system is also a powerful research tool for studying for instance medical decision-making. 相似文献
996.
Why was there a preponderance of women engaged in laboratory-based studies of animal behavior in Britain in the early years of the 20th century? As a new experimental subject with recently neglected potential, animal psychology then represented an opportunity for women to make further inroads into academic science. Because the study of psychology before World War I offered negligible professional opportunities for the application of the subject, the intake of students was restricted. Perhaps this encouraged academic access to it by aspiring female scientists who felt that career prospects, uncertain and socially unexpected of them in any case, were worth chancing for greater long-term rewards. The academic circumstances and contributions of 3 British female pioneers in experimental comparative psychology are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
997.
998.
O. R. Dornyak 《Journal of Engineering Physics and Thermophysics》2003,76(3):648-654
A rheological equation of state for wood which allows for the running values of its porosity and humidity is considered. 相似文献
999.
S. O. Balanetskii B. Grushko K. Urban T. Ya. Velikanova 《Powder Metallurgy and Metal Ceramics》2004,43(9):480-483
Scanning and transmission electron microscopy have been combined with x-ray diffraction to examine the phase equilibria in the Al - Pd - Re system at 1000°C for compositions from 50 to 100 at.% Al, and the corresponding isothermal section has been constructed. The binary monoclinic Al3 Re phase has been observed for the first time. It is confirmed that there is a stable icosahedral phase in this system. The boundaries to its homogeneity region have been determined and the phase equilibria in which it participates. 相似文献
1000.