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32.
33.
A Method of Combined SHPB Technique and BP Neural Network to Study Impact Response of Materials 总被引:2,自引:0,他引:2
Abstract: A new method combining the split Hopkinson pressure bar (SHPB) technique with the back-propagation (BP) neural network program is proposed. By this method, the treated strain wave signals become smooth with less noises induced by the transverse inertia. Moreover, the dynamic rate-dependent constitutive behaviour of materials can be identified, without any pre-assumption of a constitutive model. It is found that by taking the experimentally measured data of strain, strain rate and time as 'input' and the corresponding data of stress as 'output' of the BP neural network, the dynamic constitutive behaviour with internal damage or phase transformation evolution is easy to be identified, where the time could represent either the internal damage evolution or phase transformation process accompanied with the deformation process. It is emphasised that the data learnt by the BP neural network must include both loading and unloading processes, if the whole loading and unloading response is to be correctly predicted. The comparisons between the predictions and experimental results are in good agreement for both polyamide (PA) polymer (as an example of nonlinear viscoelastic materials) and Ti–Ni alloy (as an example of superelastic materials with stress-induced phase transformation). 相似文献
34.
本文利用最优回归设计“310”方案,研究了黑土地甜菜 Zn、K_2O、B的效果及合理施用问题。得出甜菜块根产量、含糖、产糖量、灰分 K 和有害 N 与 ZnK_2O、B 肥回归关系显著的回归模型,分析了 Zn、K_2O、B 对上述五个指标的效应,明确了 Zn 是影响各项指标的主要因子,并采用频率筛选法,提出了兼顾上述五项指标的优质高产施肥措施。 相似文献
35.
部件试验模态综合的简便方法 总被引:4,自引:1,他引:3
本文将一种基于完备模态基的模态综合技术应用于子结构的试验模态综合,获得成功。这种半试验半理论的模态综合方法是一种较为简便的、要求试验工作量较小的试验模态综合法,因为它只要求测量子结构的振动模态和频率即可。数值仿真结果表明,这种简便的试验模态综合法是行之有效的。 相似文献
36.
On the mechanical behavior of aluminum alloys reinforced by long or short alumina fibers or SiC whiskers 总被引:2,自引:0,他引:2
This study was initiated to examine the dispersion of longitudinal and transverse waves in metal matrix composites in order to obtain the dynamic elastic modulus and to evaluate various models for predicting the composite's macroscopic elastic constants from the properties of its constituents. The materials chosen for this investigation were alumina continuous fibers on the one hand and alumina and SiC short fibers on the other hand, all embedded in an aluminum alloy matrix. In addition, some indications have been obtained experimentally for the acoustoelastic effect in the composite. 相似文献
37.
凌礼富 《武汉化工学院学报》1991,(4)
本文通过对SIMATIC S5—115U可编程控制器性能的简介,简述国外PC技术的现状和发展,并提出对PC国产化的看法. 相似文献
38.
The ring-opening polymerization of hexamethylcyclodisilazane (D2NMe), initiated by methyl triflate in 1,2-dichloroethane, forms in the first, fast kinetic step both linear polymer and cyclic dimer (D4NMe). Subsequently a slow depolymerization process occurs leading to exclusively cyclotrisilazane (D3NMe). On the basis of kinetic measurements carried out using an adiabatic calorimetric technique and complementary experiments, mechanisms of both propagation, cyclization and back-biting reactions are proposed. The influence of the reaction temperature was also studied; it is demonstrated that, at low temperature, polymerization does not lead to cyclic oligomer formation. In such conditions, the polymerization presents a ‘living’ character. 相似文献
39.
Liaqat A. Khan Edward A. Wicklein E. C. Teixeira 《Canadian Metallurgical Quarterly》2006,132(7):741-746
A three-dimensional (3D) computational fluid dynamics (CFD) model of a contact tank is presented in this paper. The model results are compared against 3D velocities and flow through curve (FTC) data, representing a tracer concentration profile, from a 1:8 scale physical model. The objective is to demonstrate that CFD models can simulate both the FTC and the 3D velocity field quite well. Simultaneous validation of velocities and FTC is important in ascertaining the predictive capabilities of CFD models, as physical model studies indicate that different baffle arrangements can lead to similar FTCs. Therefore, a good prediction of only FTC, as presented in previous 3D CFD model studies, does not necessarily imply a correct simulation of the flow field. 相似文献
40.
The simultaneous contrast effect is investigated in this article. A total of 174 and 154 test/induction combinations were studied for CRT and surface colours respectively. Each combination was assessed by nine observers using a matching technique. The test and induction colours used for CRT colours were similar to surface colours using fabric samples. The results indicated a strong lightness contrast effect for both CRT and surface media; that is, the lightness of a test colour surrounded by a lighter induction colour was reduced for both CRT and surface colours. However, the effect in CRT medium was more pronounced than in the surface medium. © 2004 Wiley Periodicals, Inc. Col Res Appl, 30, 13–20, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.20074 相似文献