共查询到20条相似文献,搜索用时 687 毫秒
1.
张帆 《中国制造业信息化》2004,33(10):14-21
提起ERP、CAD、PDM或者财务软件,你总会立刻想起Oracle、SAP、利玛、并捷、和佳、金思维、用友、金蝶、UGS、PTC、欧特克、开目、艾克斯特、新洲、CAXA等等这些在行业内赫赫有名的软件厂商,但是提起OA,知道的人却少之又少,因此OA市场无“老大”也成了一个无需去争议的事实。 相似文献
2.
<正>1概述在现有的耕地及草场、绿化、林木、土地、山地、沙地上,按照需求布置相应测量点,对区域内不同深度的土壤温度、土壤水分等关系植、作物、林木等长势相关的土壤墒情信息,以及温度、湿度、光照、雨量、风速、风向、气压等空间环境信息的数据 相似文献
3.
4.
5.
车晓玲 《机械工人(热加工)》2008,(23):14-15
记者:CMF’08和CFF’08即将开展,请您介绍一下本届展会的最新进展情况。齐副秘书长:截止到目前,本届展览会共有90多家一流的锻压设备、模具和材料的展商,分别来自中国、德国、日本、美国、意大利、法国、瑞典、西班牙和荷兰等十几个国家,包括舒勒、金丰、小松产机、隔而固、SMSMEER、Lasco、扬锻、徐锻、稼本、理研、湖州机床、 相似文献
6.
《机械制造与自动化》2012,(6):24+42+102
低碳经济包括的领域低碳经济几乎涵盖了所有的产业的领域。著名学者林辉称之为"第五次全球产业浪潮",并首次把低碳内涵延展为:低碳社会、低碳经济、低碳生产、低碳消费、低碳生活、低碳城市、低碳社区、低碳家庭、低碳旅游、低碳文化、低碳哲学、低碳艺术、低碳音乐、低碳人生、低碳生存主义。 相似文献
7.
8.
9.
10.
11.
分析了链传动在实际运转过程中,紧边链条与链轮上不同圆相切的情况,从这一角度出发,当中心距和链节数以链条松、紧边与2链轮分度圆相切为条件确定后,链条紧边与链轮不同的圆相切将导致松边垂度和张力变化。 相似文献
12.
为了降低较为昂贵的镜面抛光和光机装配费用,以及应对温度、重力及其他意外因素导致的镜面低阶像差,一种在被动浮动支撑结构上施加力矩以实现面型实时校正的力矩促动器在部分望远镜上已有成熟应用。本文旨在针对我国未来的大口径地基光学望远镜,对其拼接子镜力矩促动器的分布进行优化与设计。首先根据工程经验和参考文献初步确定力矩促动器所需校正能力,通过三维建模软件对拼接子镜及镜室进行建模,最后通过有限元仿真和最小二乘法拟合对力矩促动器的布局进行优化设计。计算结果表明,采用18个力矩促动器的分布方案能够对离焦、像散、彗差、三叶像差进行良好的校正。对于具有数百面子镜的拼接望远镜来说,18个力矩促动器的方案在满足光学设计需求的同时,有效节约了建设经费并降低了工艺的复杂性。 相似文献
13.
An approximate analytical approach to the torsion of thin-walled beams of open cross-section with influence of shear is presented. It is assumed that the normal stresses in the cross-section contour direction are small compared to the normal stresses in the beam longitudinal direction that can be ignored in the stress–strain relations. The stresses and displacements are obtained in the closed analytical form. It is assumed that transverse load can be reduced to moments of torsion only, with respect to the cross-section shear centre. The beam will be subjected to torsion, with respect to the shear centre, i.e. the principal cross-section sectorial coordinate, in the case of cross-sections with two axes of symmetry; to torsion and bending in the case of cross-sections with one axes of symmetry and to torsion, bending and tension in the case of general cross-sections. An illustrative example of beam with one axis of symmetry is given. 相似文献
14.
In a recent paper, the Ritz method with simple algebraic polynomials as trial functions was used to obtain an eigenvalue equation for the free vibration of a class of homogeneous solids with cavities. The method presented is here extended to the study of a class of non-homogeneous solids, in which each solid is composed of a number of isotropic layers with different material properties. The Cartesian coordinate system is used to describe the geometry of the solid which is modelled by means of a segment bounded by the yz, zx and xy orthogonal coordinate planes and by two curved surfaces which are defined by fairly general polynomial expressions in the coordinates x, y and z. The surface representing the interface between two material layers in the solid is also described by a polynomial expression in the coordinates x, y and z. In order to demonstrate the accuracy of the approach, natural frequencies are given for both a two- and three-layered spherical shell and for a homogeneous hollow cylinder, as computed using the present approach, and are compared with those obtained using an exact solution. Results are then given for a number of two- and three-layered cylinders and, to demonstrate the versatility of the approach, natural frequencies are given for a five-layered cantilevered beam with a central circular hole as well as for a number of composite solids of more general shape. 相似文献
15.
一种外啮合齿轮泵在某些特殊的环境下连续长时间工作后会发生泄漏,针对该现象展开深入的分析,发现外界环境的振动是导致该齿轮泵泄漏的主要原因之一,尤其发现前后两个端盖以及端盖与外部接头的连接处是容易发生泄漏的区域。借助大型有限元分析软件ANAYS,建立该类型齿轮泵的有限元模型,并且对该泵壳体进行动力学分析,提取前八阶模态,找出其振型和频率。 相似文献
16.
17.
18.
19.
A hole-flanging operation on a flat circular sheet with a hole in the center is simulated by an incremental elasto-plastic finite-element method, which incorporates strain-hardening and anisotropy in the direction normal to the sheet, with care taken to describe the boundary conditions of penetration, separation and the alternation of the sliding—sticking state of friction. The simulation clearly demonstrates the processes of generation of deformation shape until unloading. The calculated sheet geometries and the relationship of punch load to punch stroke are in good agreement with the experimental data.The stress at the hole periphery in the flange is assumed to a state of circumferential uniaxial tension, in order to simplify the fracture mode as a simple tension test. By making use of the instability of uniaxial tension, an approximate relationship to determine the onset of necking of the hole periphery in the hole-flanging process is derived and it is found to be influenced by the process geometry and the plastic properties of the material, such as the stress-concentration factor K, strain-hardening n and normal anisotropy R, and the estimated value, being obtained by the derived equation, agrees well with the experimental data.It is noted that the derived relationship for estimating the instability of the hole-flanging process can be combined into the developed finite-element model to simulate the critical condition of the limiting deformation of the hole-flanging process. This combined method could possibly be applied towards improving both the manufacturing process and the design of tools for the hole-flanging operation. 相似文献