下运可伸缩带式输送机的设计

介绍了下运可伸缩带式输送机的设计要点,对储带仓、制动装置的布置位置,给出了理论分析,并对现场调试出现的问题作了分析和总结,提出了更加合理的设计方案.     

一种改进的可扩展标记语言查询增量维护算法

为降低可扩展标记数据查询执行器重新构建的代价,提出了一种基于树型结构的可扩展标记语言查询增量维护算法.该算法利用树型结构进行可扩展标记语言数据流查询执行器增量维护,利用自动机来表示状态转换,从而实现了对可扩展标记语言树型结构的动态维护,避免了在没有文档类型定义情况下出现的环形结构的复杂操作,减少了维护时间和状态转换数量.实验表明,基于树型结构的可扩展标记语言查询增量维护算法能够以有限转换路径为代价,有效地完成可扩展标记语言数据流持续查询执行器的动态维护,减少了增量维护时间和状态转换数量.     

Influence of process parameters in mechanical clinching with extensible dies

The influence of clinching tool design in joining metal sheets by the clinching process with extensible dies is investigated. The material flow during the clinching process was examined experimentally and numerically. The geometrical and mechanical characteristics of joints produced under different processing conditions, that is, forming loads, were used to calibrate and validate a 3D finite element model of the clinching process. Then, the model was utilized to evaluate the influence of clinching tool design parameters, namely the punch diameter, the punch corner radius, the fixed die depth, the fixed die diameter, and the die corner radius. The effects of design parameters on the cross section of a clinched joint, the required forming load and the joint strength were analysed and the appropriate processing window was determined. According to the achieved results, the main benefits and drawbacks of each configuration are discussed.     

微型飞行器结构的发展及关键技术

微型飞行器从概念的出现到现在的研究与发展,已经经历了很多,出现了各式各样的微型飞行器。介绍了当前微型飞行器所涉及的主要结构及其特点,同时对微型飞行器需要突破的技术和方向进行了阐述。     

基于可伸展变形的双稳态圆柱壳计算模型

为提高双稳态复合材料圆柱壳设计的准确性和效率,基于可伸展变形和均匀曲率假设,提出复合材料圆柱壳双稳态特性分析的简化理论模型;利用Python语言,基于仿真软件Abaqus进行二次开发,建立了实现复合材料圆柱壳快速、参数化建模与自动后处理的插件。利用所提模型讨论了几何参数、铺设参数、温度对复合材料圆柱壳双稳态特性的影响。通过实验验证了计算模型的有效性和准确性。结果表明,该计算模型可满足复合材料圆柱壳的设计需求,为后续双稳态圆柱壳的优化设计奠定基础。     

面向企业应用系统的可扩展的企业模型研究

为了满足不同的企业应用系统对企业模型的需求,提出一种可扩展的企业模型.该模型包、括核心层、基本层和扩展层三个层次,核心层描述模型的核心概念,基本层模型综合当前的企业建模方法对核心层模型进行初始扩展,以适应应用系统的共性需求,扩展层模型通过扩展机制,并根据用户需求进行动态扩展.详细论述了每个层次的模型、一致性规则约束下模型的扩展机制和基于扩展方法的建模过程.     

Nondestructive testing of steel rods

The possibility of the detection of hidden flaws in magnetization with a geomagnetic field was determined experimentally. Steel rods 3 mm in diameter and 2 m long, which were prepared from a wire that is used in shock absorber springs, were used as test objects.     

The extensible elastica of a prestressed beam with arbitrary boundary conditions

An axially prestressed elastic beam with arbitrary boundary conditions is considered. The solution of the problem is sought within the non-linear bending theory derived under the assumptions of finite deflections and small strains. The extensibility of the beam axis is taken into account, while the influence of shear force is neglected. A set of transcendental equations with incomplete elliptic integrals is obtained as the general solution. For small deflections, a linear solution of the problem is given too. Several numerical results for the case of prestressed bolt in a joint are discussed and presented in the form of appropriate diagrams.     

Buckling of rotating rods and plates

The elastic instability of two basic structural elements, rods and plates, when subjected to compressive stresses arising from steady rotation is considered. The resulting eigenvalue problems are defined and in each case numerical procedures are employed which determine the critical rotational speed and its dependence on the relevant parameters.     

数控车床结构布局形态方案创成研究

研究了概念设计阶段机床结构布局形态方案的创成式设计方法。依据所建立的机床形状创成模型，通过解析方法创成出所有可能的机床运动功能方案，然后基于机床运动单元与结构单元之间的关系模型，由机床的运动功能方案创成出机床结构布局形态方案。通过数控车床结构布局形态方案创成，证明本创成式设计方法对概念设计阶段机床总体结构方案的创新性设计且有指导意义．     

Point mass identification in rods

The possibility of applying the acoustic free-vibration method to diagnose rods with localized masses is considered. Calculation data of vibration frequencies of loaded and unloaded rods that were obtained using the proposed model and other author’s models are compared.     

On the buckling of rotating rods

The critical rotating speed causing buckling of an axially prestressed rotating rod attached to the rim of a ring is investigated by using the extended Galerkin procedure with shape functions represented by a complete set of Legendre polynomials. The study accounts for the effect of the bar setting angle, and the stability boundary is established based on a two term approximation.     

奇异接近度的评价方法

奇异是机构的常见特性.在并联机构的奇异点附近,动平台的力/力矩输出能力会明显降低.因此,判定工作空间内一点距离奇异的远近程度是并联机构设计的一个重要问题.针对这一问题,定义两种测度指标,分别用来度量位置奇异和姿态奇异的接近度,并用该指标定义拟奇异空间,该空间由所有接近奇异的点组成.当机构工作在拟奇异空间之外的任务空间,即可保证驱动关节力矩不超出驱动电动机的物理极限.最后以平面3-RRR机构为例,给出两种指标的计算方法和拟奇异空间以及任务空间的求解方法.     

铰链机构磨损的数值仿真

以数值仿真技术对曲柄滑块机构中的铰链摩擦副磨损状态进行了研究；考虑到压力和温度的影响，建立了铰链机构的磨损仿真模型；对机构中三对铰链接触处的磨损提出了具体的算法方案，在Visual Basic环境下编写了通用程序，获得了更加准确的仿真结果。     

产品拆卸配置优化研究

通过对产品拆卸内在规律的分析 ,建立产品拆卸 BOM“与 /或”树模型。以产品拆卸 BOM“与 /或”树模型为基础 ,提出产品拆卸经济性优化配置算法 ,通过合理的数据结构提高计算速度 ,并设计了该算法的实现模块     

模块化可重构机器人的构形在线自主辨识

针对模块化可重构机器人(Modular reconfigurable robot,MRR)构形复杂多变的特点,提出一种基于上层数据库和底层接口电路相结合的构形在线自主辨识方法。以所研制的MRR系统样机为研究对象,介绍关节、连杆、基座和夹爪等四类基本功能模块的结构及特殊接口电路设计;考虑多模块组合运动形式的等效性,以及同类型关节模块在输出力/力矩方面的差异,改进MRR构形空间的计算方法。利用图论中树的相关理论,在定义同类构形生成树和同序构形树枝的基础上,建立MRR构形辨识的总体研究模型,包括同类构形生成树辨识、同序构形树枝辨识和边约束条件辨识三个部分。根据模型中各部分的具体辨识对象,通过构建基本功能模块的上层数据库,并结合底层接口电路的特殊设计,实现机器人在无人参与情况下的构形在线自主辨识。以MRR系统样机为试验平台,通过多次构形辨识试验证明该方法的可行性和有效性。     

图解张拉整体基本单元稳定构型

张拉整体结构是由受拉的索构件及受压的杆构件组成的自平衡结构体系.基本柱、台结构单元,是构成任意复杂结构的基础.规则分形条件下,基于构件空间几何位置及构件力与构件矢量关系,简洁明了地获得了主辅分形参数:杆数目p、共节点杆与斜索另一端连接节点序号差j之间需要满足的空间几何位置关系.该几何关系以构件施加给节点的力平衡来表征....     

A Comparative Study of Some Two-Lobed Journal Bearing Configurations

The two-lobed configurations considered for the present study are: the elliptical bearing, offset-halves bearing and two other configurations which are geometrical variations of the first two bearing forms. A companion of their performance characteristics has been obtained by theoretical analysis. It has been shown that, unlike elliptical and offset-halves bearings, which have only limited range of effective dynamic performance, a two-lobe configuration can provide consistently good dynamic performance over a wide range of load conditions.     

Improvement of four anode rods ion source

In this work, an improved form of a saddle field ion source has been designed and constructed. It consists of four anode rods made from copper and two copper cathode discs. The two cathode discs are placed symmetrically on both sides of the four anode rods. The electrical discharge and output ion beam characteristics were measured at different pressures using argon gas. The optimum distance between each two anode rods was determined. Also the optimum distance between the four anode rods and any cathode disc was obtained. It was found that the optimum distance between each two anode rods equal to 6 mm, while the optimum distance between the four anode rods and any cathode disc equal to 16 mm, where a stable discharge current and maximum output ion beam current can be obtained. The effect of negative extraction voltage applied to both the extractor electrode and Faraday cup on the output ion beam current was studied. The sputter yield of copper and aluminum targets using argon ions of different energies was determined.     

A Wind Tunnel Two-Dimensional Parametric Investigation of Biplane Configurations

This paper presents an experimental and systematic investigation about how geometric parameters on a biplane configuration have an influence on aerodynamic parameters. This experimental investigation has been developed in a two-dimensional approach. Theoretical studies about biplanes configurations have been developed in the past, but there is not enough information about experimental wind tunnel data at low Reynolds number. This two-dimensional study is a first step to further tridimensional investigations about the box wing configuration. The main objective of the study is to find the relationships between the geometrical parameters which present the best aerodynamic behavior： the highest lift, the lowest drag and the lowest slope of the pitching moment. A tridimensional wing-box model will be designed following the pattern of the two dimensional study conclusions. It will respond to the geometrical relationships that have been considered to show the better aerodynamic behavior. This box-wing model will be studied in the aim of comparing the advantages and disadvantages between this biplane configuration and the plane configuration, looking for implementing the box-wing in the UAV＇s field. Although the box wing configuration has been used in a small number of existing UAV, prestigious researchers have found it as a field of high aerodynamic and structural potential.