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排序方式: 共有274条查询结果,搜索用时 15 毫秒
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Berlin Wu 《Computational Economics》1994,7(1):37-53
In this paper, the methods of time series for nonlinearity are briefly surveyed, with particular attention paid to a new test design based on a neural network specification. The proposed integrated expert system contains two main components: an identification environment and a robust forecasting design. The identification environment can be viewed as a integrated dynamic design in which cognitive capabilities arise as a direct consequence of their self-organizational properties. The integrated framework used for discussing the similarities and differences in the nonlinear time series behavior is presented. Moreover, its performance in prediction proves to be superior than the former work. For the investigation of robust forecasting, we perform a simulation study to demonstrate the applicability and the forecasting performance. 相似文献
3.
In unidirectionally reinforced composites with an elastic-plastic matrix, there is a plastic zone with lengthY
0 proportional to the crack lengthC (Y
0 C) at the tip of a crack. This results in a new logarithmic dependence of glass and aramid PABI fibre-reinforced plastics (FRP) on crack length and non-fulfilment of the Griffith criterion. In glass and PABI FRP without an artificial notch, defects already exist equivalent to a crack with a length depending on composite fabrication practice. In GFRP, the epoxy matrix shear yield stress grows 2.0 to 2.5 times, compared to the yield in thin films due to fibre constraint of matrix yielding. The stress distribution in front of a crack in a highly anisotropic composite with an elastic-plastic matrix is derived. The stress concentration at the tip of a crack grows with increasing matrix yield stress, resulting in a change of failure mode from accumulation of fibre breaks at low matrix strength, to brittle failure at high matrix strength. The following factors lead to composite embrittlement: (1) increase of matrix yield stress and composite shear strength; (2) decrease of temperature; (3) increase of Young's modulus of the fibre; (4) reduction of fibre strength. The dependence of aramid PPTA FRP strength on temperature exhibits a maximum. Epoxy matrix plastification leads to some increase of aramid PPTA FRP strength. 相似文献
4.
LI Ximing CHEN Jiayong Institute of Chemical Metallurgy Academia Sinica Beijing ChinaR.KAMMEL Institut Für Metallurgie Technische Universitt Berlin Germany Research Assistant Institute of Chemical Metallurgy Academia Sinica Beijing China 《金属学报(英文版)》1992,5(9):153-157
The influence of mechanical activation on the leaching behaviour of scheelite was studied bymeans of fine grinding in an attritor and subsequently HCl leaching in presence of PO_4~(3-).Results showed that after fine grinding in the attritor,the reaction rate of scheelitewith HCl-Na_3PO_4 solution was remarkably increased,the extraction of W increased fromabout 8 to 99%.The IR spectra and X-ray diffraction analysis indicated that in addition toan enlargement of surface area the fine grinding action had made also changes of fine struc-ture and reactivity of solid surface,hence the leaching process of scheelite can be carried outunder mild leaching conditions. 相似文献
5.
Konoplev A. A. Berlin A. A. Aleksanyan G. G. Rytov B. L. 《Theoretical Foundations of Chemical Engineering》2002,36(2):195-197
Theoretical Foundations of Chemical Engineering - 相似文献
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Caroline Gollub Stanislav Avdoshenko Rafael Gutierrez Yuri Berlin Gianaurelio Cuniberti 《Israel journal of chemistry》2012,52(5):452-460
Charge migration is a ubiquitous phenomenon with profound implications throughout many areas of chemistry, physics, biology, and materials science. The long-term vision of designing functional materials with tailored molecular-scale properties has triggered an increasing quest to identify prototypical systems where truly molecular conduction pathways play a fundamental role. Such pathways can be formed due to the molecular organization of various organic materials and are widely used to discuss electronic properties at the nanometer scale. Here, we present a computational methodology to study charge propagation in organic molecular stacks at nano and sub-nanoscales and exploit this methodology to demonstrate that moving charge carriers strongly affect the values of the physical quantities controlling their motion. The approach is also expected to find broad application in the field of charge migration in soft matter systems. 相似文献
8.
James F. Hoebel Gordon H. Damant Steven M. Spivak Geoffrey N. Berlin 《Fire Technology》2010,46(3):629-649
Between 1997 and 2006, more than 4,300 serious burn injuries per year in the United States were associated with clothing.
Ages 5–14 had the highest average annual burn injury rate, and ages 25–64 had the lowest rate. There were 120 deaths per year
in the United States associated with clothing burns between 1999 and 2004. The death rate for those over 65 was six times
the national average. The General Wearing Apparel Standard has regulated the flammability of clothing worn in the United States
since 1953. Nearly all of the clothing-related injuries and deaths have occurred in fires involving apparel that complied
with this Standard. Despite the size of this problem, there is no organized national activity under way to begin to address
these casualties. Experience with the Children’s Sleepwear Flammability Standards, issued in the 1970s, suggests that safer
garments can be manufactured that would prevent many clothing burn injuries and deaths. A more stringent up-to-date flammability
standard, production of safer garments, use of warning labels, and educated consumers are needed. 相似文献
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