共查询到20条相似文献,搜索用时 93 毫秒
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<正>刚出火车站,天空幽蓝,空气湿润,寻路未果,索一路人,依其指点,穿过条条巷道,眼前便是一望无际的大海了,心情一下子就豁然开朗,长途的疲累此时早已 相似文献
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工程机械发展对液压技术的需求动向 总被引:2,自引:0,他引:2
进入21世纪以来,世界工程机械发展处于低迷状态,平均增长率有下降趋势,2001年比2000年下降2.2%,自2003年开始,工程机械销售额有一定增长,以日本为例,2003年销售额约100亿美元,比2002年增长15%,其中内需为5247亿日元,增长4%,外需(出口)为6296亿日元,约占总销售额的1/2,增长20%,外需增长主要是中国及亚洲市场需求激增的缘故。由于日本对废气排出量有新的限制,使设备更新量增大,例如,液压挖掘机增长8%,汽车起重机增长12%。据日本建设机械协会预测,2004年日本工程机械将增长9%,达110亿美元,其中液压挖掘机增长16%,小型挖掘机增长6%,由于建设项目… 相似文献
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中国机械工业联合会 《机械工业标准化与质量》2005,(2):6-9
中国机械工业联合会是为适应国家工业管理体制改革需要,经国务院同意、民政部批准,于2001年4月正式成立的综合性行业协会。按照国家标准委和国家发展改革委的授权,三年多来,特别是在2004年,我们以科学发展观为指导,以市场需求为导向,以为政府、为企业服务为宗旨,本着不“越位”、不“错位”、不“缺位”的工作原则,围绕振兴机械工业,开拓创新,强化服务, 相似文献
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岚县位于山西省西北部,吕梁山北端高寒山区,地处黄河流域中部,属晋西北黄土高原山区.辖3镇9乡,面积1 514 km2,境内多为丘陵区,地势较为平坦,平均海拔1200 m以上,平均气温6.8 ℃,有效积温2 727 ℃,日温差14.7 ℃,年平均降雨为504.9 mm,无霜期为90~125 d.独特的自然条件,既是理想的马铃薯生产区域,又适宜机械化生产.全县粮田面积3万hm2,其中马铃薯每年种植面积均在1万hm2以上.占粮田面积的1/3,是农民收入的重要来源之一.实现马铃薯机械化生产具有得天独厚的优势. 相似文献
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For optimal design of constant stress accelerated life test(CSALT) with two-stress, if the stresses could not reach the highest levels simultaneously, the test region becomes non-rectangular. For optimal CSALT design on non-rectangle test region, the present method is only focused on non-rectangle test region with simple boundary, and the optimization algorithm is based on experience which can not ensure to obtain the optimal plan. In this paper, considering the linear-extreme value model and the optimization goal to minimize the variance of lifetime estimate under normal stress, the optimal design method of two-stress type-Ⅰ censored CSALT plan on general non-rectangular test region is proposed. First, two properties of optimal test plans are proved and the relationship of all the optimal test plans is determined analytically. Then, on the basis of the two properties, the optimal problem is simplified and the optimal design method of two-stress CSALT plan on general non-rectangular test region is proposed. Finally, a numerical example is used to illustrate the feasibility and effectiveness of the method. The result shows that the proposed method could obtain the optimal test plan on non-rectangular test regions with arbitrary boundaries. This research provides the theory and method for two-stress optimal CSALT planning on non-rectangular test regions. 相似文献
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液体动压径向滑动轴承的概率多目标优化设计 总被引:6,自引:0,他引:6
运用可靠性设计理论和优化设计技术 ,提出了液体动压径向滑动轴承的概率优化设计方法 ;建立了其概率多目标优化设计的数学模型 ;求解该模型 ,可得到总体最优的设计方案 ,使轴承在满足承载能力及强度要求条件下 ,功耗和温升最低 ,体积减小。 相似文献
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基于非劣最优理论的PSO多目标设计的应用 总被引:1,自引:0,他引:1
介绍基于非劣最优理论的粒子群优化算法所进行的多目标优化设计,以斜齿轮体积和传动平稳可靠性为目标函数,建立斜齿圆柱齿轮传动的多目标设计数学模型。为高速运转状态下,斜齿轮设计提供一种快速、优化的好方案。 相似文献
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FangShijie LiLi 《机械工程学报(英文版)》2003,16(1):31-33
A novel method of realizing the optimal transmission of the crank-and-rocker mechanism is presented,The optimal combination design is made by finding the related optimal transmission parameters ,The diagram of the optimal transmission is drawn ,In the diagram,the relation among minimum transmission angle,the coeffcient oftravel speed variation,the oscillating angle of the rocker and the length of the bars is shown,concisely,conveniently and directly,The method possesses the main characteristic,That is is to achieve the optimal transmission parameters under the transmission angle by directly choosing in the diagram,according to the given requirements ,The characteristics of the mechanical transmission can be improved to gain the optimal transmission effect by the method,Especially,the method is simple and convenient in practical use. 相似文献
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Fang Shijie Li LiDepartment of Mechanical Engineering Yantai University Yantai China 《机械工程学报(英文版)》2003,16(1)
A novel method of realizing the optimal transmission of the crank-and-rocker mechanism is presented. The optimal combination design is made by finding the related optimal transmission parameters. The diagram of the optimal transmission is drawn. In the diagram, the relation among minimum transmission angle, the coefficient of travel speed variation, the oscillating angle of the rocker and the length of the bars is shown, concisely, conveniently and directly. The method possesses the main characteristic. That it is to achieve the optimal transmission parameters under the transmission angle by directly choosing in the diagram, according to the given requirements. The characteristics of the mechanical transmission can be improved to gain the optimal transmission effect by the method. Especially, the method is simple and convenient in practical use. 相似文献
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机械结构分布参数优化设计是机械优化设计中的一类典型问题 ,优化设计的目的是寻找一个优化曲线 ,使得目标函数取得极值。从机械结构分布参数优化设计问题入手 ,通过分析、变换 ,引入极大值原理 ,结合共轭梯度法进行求解 ,从而得到了求解这类问题的一种新方法———梯度极值法。 相似文献
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将模糊优化方法应用于滚柱活齿传动的优化设计,建立了以体积最小为目标的单目标模糊优化数学模型。利用MATLAB工具箱采用比惩罚函数更优的序列二次规划方法进行约束优化计算,结果证明这种方法是有效的。 相似文献