排序方式： 共有11条查询结果，搜索用时 31 毫秒
1.
为考察 L OM原型件尺寸稳定性 ,研究了时间和环境因素对其尺寸精度和质量变化的影响效果 .结果表明 ,LOM原型件尺寸和质量呈增加趋势 ,其主要原因是成型后的弹性恢复和吸湿 ,且主要表征为 Z(高度 )方向的尺寸增长 .原型件结构的自约束性可有效减小 Z向尺寸增长 相似文献
2.
Fault diagnosis of valve clearance in diesel engine based on BP neural network and support vector machine 总被引：1，自引：0，他引：1
Based on wavelet packet transformation(WPT), genetic algorithm(GA), back propagation neural network(BPNN)and support vector machine(SVM), a fault diagnosis method of diesel engine valve clearance is presented. With power spectral density analysis, the characteristic frequency related to the engine running conditions can be extracted from vibration signals. The biggest singular values(BSV)of wavelet coefficients and root mean square (RMS)values of vibration in characteristic frequency sub-bands are extracted at the end of third level decomposition of vibration signals, and they are used as input vectors of BPNN or SVM. To avoid being trapped in local minima, GA is adopted. The normal and fault vibration signals measured in different valve clearance conditions are analyzed. BPNN, GA back propagation neural network (GA-BPNN), SVM and GA-SVM are applied to the training and testing for the extraction of different features, and the classification accuracies and training time are compared to determine the optimum fault classifier and feature selection. Experimental results demonstrate that the proposed features and classification algorithms give classification accuracy of 100%. 相似文献
3.
板料成形模拟及其在汽车覆盖件冲压过程中的应用 总被引：3，自引：0，他引：3
基于板料成形模拟的必要性和汽车覆盖件成形的复杂性 ,提出有限元分析是模拟复杂三维板料成形问题的有力工具 .介绍了动态显式有限元法的原理和特点 ,讨论了国际现有的各种商用软件 ,论述了汽车覆盖件模拟的国内外应用现状 .以某新型汽车前门外板为例 ,运用显示有限元分析软件Dynaform对前门外板冲压过程进行了计算机模拟分析 ,预测冲压过程中可能出现的各种工艺缺陷 ,例如坯料的破裂 ,并以模拟结果为依据提出改进方法 . 相似文献
4.
Ｔｈｅｐｈｉｌｏｓｏｐｈｙｏｆｒａｐｉｄｐｒｏｔｏｔｙｐｉｎｇａｎｄｍａｎｕｆａｃ ｔｕｒｉｎｇ (ＲＰ＆Ｍ)ｉｓ“ｌａｙｅｒｅｄｍａｎｕｆａｃｔｕｒｉｎｇａｎｄｌａｙｅｒ ｂｙ ｌａｙｅｒａｃｃｕｍｕｌａｔｉｎｇ” .ＴｈｅＲＰ＆Ｍｔｅｃｈｎｏｌｏｇｙｉｓｄｒｉｖｅｎｂｙｔｈｒｅｅ ｄｉｍｅｎｓｉｏｎａｌＣＡＤｍｏｄｅｌａｎｄｍａｋｅｓＣＡＤ/ＣＡＭｉｎ ｔｅｇｒａｔｅｄ .ＴｈｅｓｅｆｅａｔｕｒｅｓｏｆＲＰ＆Ｍｍａｋｅｉｔｗｉｄｅｌｙａｐ ｐｌｉｅｄｉｎｍａｎｙｉｎｄｕｓｔｒｉａｌｆｉｅｌｄｓｓｕｃｈａｓ… 相似文献
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基于质量、功能、性能及模型的概念基础上,针对大型复杂制造装备进行模型分析.说明如何建立装备的功能模型,并对装备的性能模型提出了构想;涉及设计过程理论、性能需求驱动理论、知识流理论和多利益方协调理论,为大型复杂装备的性能优化提供了相关依据. 相似文献
6.
The structural circumferential periodicity of inertial excitation produced by concentrated mass was utilized to establish the mathematical model of thin circular plate carrying eccentric concentrated mass and to analyze its transverse vibration. The fundamental frequency coefficient, natural frequency and mode shape function are determined by this method. A clamped thin circular plate was taken as an example to study the mass effect on the vibrating system.Comparison between the present results and published ones exhibits excellent agreement, which shows that the analytical method in this paper can be used to predict the transverse vibration parameters accurately. 相似文献
7.
The structure stiffness of presses has great effects on the forming precision of workpieces, especially in near-net or net shape forming. Conventionally the stiffness specification of presses is empirically determined, resulting in poor designs with insufficient or over sufficient stiffness of press structures. In this paper, an approach for the structure design of hydraulic presses is proposed, which is forming-precision-driven and can make presses costeffective by lightweight optimization. The approach consists of five steps:(1)the determination of the press stiffness specification in terms of the forming precision requirement of workpieces;(2)the conceptual design of the press structures according to the stiffness and workspace specifications, and the structure configuration of the press;(3)the prototype design of the press structures by equivalently converting the conceptual design to prototypes;(4)the selection of key structure parameters by sensitivity analysis of the prototype design; and(5)the optimization of the prototype design. The approach is demonstrated and validated through a case study of the structure design of a 100 MN hydraulic press. 相似文献
8.
A power system with proton exchange membrane fuel cells (PEMFC) was designed for thermal underwater glider.Heat generated by PEMFC is used as the propulsion power of the glider,and the electricity is used in the control and sensor system.An electric energy storage system (ESS) is required which possesses high power density with good cycle life.Ultracapacitors which exhibit high power density and cycle life are considered as energy storage devices.Simulations based on a specific voyage condition indicate that ESS with ultracapacitors has positive effects on reducing the output power demand of PEMFC and lightening the power system.Experimental results show that the state of charge (SOC) is related to the capacitance and resistance in ultracapacitor ESS. 相似文献
9.
The optimal panel thickness of an automotive door hasto beidentifiedtosatisfysuchrequirements as highrigidity,natural frequency, and side impact safety, coupled withminimumweight .Therefore ,the use of structural optimiza-tionfor vehicle door design hasin… 相似文献
10.
思想政治工作是构建和谐企业的重要保障 总被引：3，自引：0，他引：3
在新形势下,思想政治工作在构建和谐企业中的作用越来越重要,是构建社会主义和谐企业的重要途径和抓手。思想政治工作只有不断创新工作形式和方法,紧紧围绕构建和谐企业开展工作,才会有强大的生命力和活力,为构建和谐企业提供重要保障。 相似文献