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排序方式: 共有6571条查询结果,搜索用时 15 毫秒
1.
针对地雷的毁伤目标和特性,提出一种新颖的多棱柱状药型罩结构,其可看作由八个楔形罩对称排列相邻连接而成。应用非线性有限元软件完成了爆炸载荷下多棱柱状药型罩形成射流过程的数值模拟,结果表明新型药型罩结构能够实现预期设想,形成一股汇聚射流。研究结果为地雷战斗部研究提供了一种新的选择。  相似文献   
2.
To realize ultimately efficient signal processing, it is necessary to replace electrical signal processing circuits with optical ones. The optical micro-resonator, which localizes light at a certain spot, is an essential component in optical signal processing. Single-crystal calcium fluoride (CaF2) is the most suitable material for a highly efficient optical micro-resonator. The CaF2 resonator can only be manufactured by ultra-precision machining processes, because its crystal anisotropy does not allow the application of chemical etching. However, the optical micro-resonator's performance depends definitely on the surface integrity.This study investigated the relationship between surface quality after ultra-precision machining and crystal anisotropy. Firstly, crack initiation was investigated on the (1 0 0), (1 1 0), and (1 1 1) planes using the micro-Vickers hardness test. Secondly, brittle-ductile transition was investigated by orthogonal cutting tests. Finally, cutting performance of cylindrical turning was evaluated, which could be a suitable method for manufacturing the CaF2 resonator. The most difficult point in cylindrical turning of CaF2 is that the crystalline plane and cutting direction vary continuously. In order to manufacture the CaF2 optical micro-resonator more efficiently, analysis was conducted on crack initiation and surface quality of all crystallographic orientations from the perspective of slip system and cleavage.  相似文献   
3.
To improve the convertibility of reconfigurable manufacturing system (RMS), the concept of delayed reconfigurable manufacturing system (D-RMS) was proposed. RMS and D-RMS are both constructed around part family. However, D-RMS may suffer from ultra-long system problem with unacceptable idle machines using generic RMS part families. Besides, considering the complex basic system structure of D-RMS, machine selection of D-RMS should be addressed, including dedicated machine, flexible machine, and reconfigurable machine. Therefore, a system design method for D-RMS based on part family grouping and machine selection is proposed. Firstly, a part family grouping method is proposed for D-RMS that groups the parts with more former common operations into the same part family. The concept of longest relative position common operation subsequence (LPCS) is proposed. The similarity coefficient among the parts is calculated based on LPCS. The reciprocal value of the operation position of LPCS is adopted as the characteristic value. The average linkage clustering (ALC) algorithm is used to cluster the parts. Secondly, a machine selection method is proposed to complete the system design of D-RMS, including machine selection rules and the dividing point decision model. Finally, a case study is given to implement and verify the proposed system design method for D-RMS. The results show that the proposed system design method is effective, which can group parts with more former common operations into the same part family and select appropriate machine types.  相似文献   
4.
M1080B无心外圆磨床砂轮及导轮宽度较窄,磨削轴承套圈外圆时,磨削效率低,托板架调整较为繁琐、皮带打滑、磨损较为严重。针对上述问题,提出了相应的解决办法,提高了磨削效率。  相似文献   
5.
Abstract

Generalized thermoelastic interactions due to three-phase-lag time-nonlocal heat transfer in a Kelvin-Voigt type infinitely extended visco-thermoelastic continuum with cylindrical cavity has been investigated. The two-temperature generalized thermoelasticity theory has also been taken into account. The problem has been solved in the domain of Laplace on the assumption that the surface of the cavity is free from traction and is subjected to a smooth and time-dependent-heating effect. Laplace inversion of the transformed solutions has been carried out numerically. The obtained numerical data for different considerations are plotted in graphs to study the effects of time-nonlocal parameter, two-temperature parameter and visco-thermoelastic relaxation parameter on different thermoelastic quantities of physical interest.  相似文献   
6.
The exactness and stability of the Wilkins method in the investigation of the stress-strain state of axisymmetric anisotropic elastic shells, including thick-walled ones, have been studied for different values of artificial viscosity, pulse load rise and fall time, and different deformation process durations. A comparison of numerical calculations, performed by means of an application software package developed by V. A. Romashchenko on the basis of the Wilkins method, with experimental results, known numerical data, and with calculations using the computation kernel LS-DYNA 3D has been carried out.  相似文献   
7.
评述了ISO 5 75 5“烧结金属材料—规范”和美国MPIF标准 35的变迁和趋向统一。阐述了“最小强度值”的意义。说明了我国粉末冶金结构零件材料标准的现状  相似文献   
8.
赵丰年 《衡器》2008,37(2):22-25
阐述静态电子轨道衡诸多优点;工作原理、允许误差及误差分配;轨道衡的结构组成部分、解析各部分的工作特性及技术指标要求;合理选配及推荐实例.  相似文献   
9.
推导出激光二极管线阵光束通过透镜系统的光强分布表达式,分析了出射光束的传输特性,设计一种凹柱透镜的光束变换系统得到一维均匀光强分布。此外,给出扩展角宽度的计算公式。  相似文献   
10.
结构-波浪-海床耦合系统中大圆筒结构的波压力响应   总被引:5,自引:2,他引:3  
刘海笑  王仲捷 《水利学报》2003,(4):67-73,79
以沉入式大圆筒结构为对象,通过设计随机波浪水槽实验,测取了在单筒和连续筒两种结构型式、两种沉入深度和两种波谱输入下结构表面的动波压力分布。波面高度以及波压力历程均在领域进行分析。通过计算结构表面沿高程和沿环向的波压力谱及波压力传递函数,将单筒实测结果与基于线性绕射理论的解析解进行了比较,同时也详细对比了两种结构型式下的实测结果。文中汇报了在研究中获得的新发现及进行的相应分析,特别是在结构——波浪——海床动力相互作用下对波压力响应机理以及针对连续筒的研究,可为工程应用提供有价值的参考。  相似文献   
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