基于ER 模型的自动装配设计

提出了一种基于ER模型的自动装配设计方法。根据机械系统和零件的特点,建立了机械系统和零件的ER模型;分析机械系统和零件的ER模型,建立了机械系统和零件的数据库表结构,通过数据库表结构描述了机械系统的拓扑关系和基本属性,实现系统的自动装配设计。基于Pro/Engineer软件提供的Pro/Toolkit二次开发工具,给出...     

机械强度数据库需求分析与体系表的建立

介绍了在建立机械强度数据库过程中,如何引进数据库的需求分析,主要考虑了哪些因素。在需求分析基础上,进行了数据库总体设计,建立了数据库体系表。扼要介绍了体系表的基本内容以及所考虑的主要问题。     

电厂KKS编码及其管理系统设计

介绍了KKS编码系统及其特点，并与属性码、位置码和流水码进行了比较，针对具体工程需要采用Aeess数据库建立了KKS编码索引和某电厂具体的KKS编码的数据库表，利用VC来设计其操作界面，对数据库的访问则采用了MFC的DAO技术，最后介绍了本KKS管理系统的备项功能。     

工程图纸中标题栏单元信息提取与识别技术研究

工程图纸上的标题栏信息是产品数据集中管理的重要数据来源。通过分析标题栏信息表的构成特点，提出了基于单元概念的描述方法，在此基础上采用基表来表达同类信息表的格式，并建立基表与数据库之间的映射关系。通过单元识别和格式识别，获取标题栏信息表的所有信息，在同格式基表映射关系的约束下，实现标题栏信息的自动提取和入库。开发了实用程度并在工程项目中得到应用。     

Access数据库在CAD设计中的应用

在AutoCAD2000中建立图形对象和Access数据库表之间的关联。     

洗衣机图形数据库的开发

介绍开发洗衣机图形数据库,通过中间数据文件建立起图形数据与数据库表的对应关系。“刷新标题栏”时读出这个中间数据文件,用这些数据更新标题栏或零件表的项目内容。用户操作简单、直观性强。图形数据库模块中的数据方便地被用于整个洗衣机数据库管理系统。     

机车检修整备管理系统中数据库的设计及优化

针对当前机车整备工作的实际需求,按照数据库的优化原则,从内存分配、优化磁盘I/O和配置操作系统性能几个方面进行数据库优化,用Oracle优化器对SQL语言进行了优化,建立了人员信息表、机车工位字典表等一系列关系数据表和数据库视图,最后设计出数据库存储过程和数据库触发器.本机车检修整备管理系统在某铁路局运行良好,符合信息管理优化设计要求.     

Access数据库在CAD设计中的应用

在AutoCAD2000中建立图形对象和Access数据库表之间的关联.     

换热器CAPP系统开放式结构的研究与实现

针对换热器CAPP系统和开放式程序结构,提出基于数据库的换热器CAPP系统总体结构,建立基于数据库的CAPP系统,实现数据库表结构设计和维护的开放性,应用程序在图形绘制、数据输入、打印输出和制造工序编制等方面都具有良好的开放性。     

基于生产流程的船舶管加工车间信息模型的研究

对数字化造船管加工车间生产流程及现状进行研究,以信息化造船为重点,进行管加工车间信息模型体系的分析,并建立管加工车间数据中心。结合船舶管系的设计和制造特点,分析船厂管子加工车间对管子数据的要求,建立适应数字化造船的基于TRIBON的管系产品数据库,该数据库能实现数据导入、托盘表生成、数据查询功能。基于生产流程的船舶管件数字化加工车间信息模型,对于现阶段处于向数字化造船模式转变中的企业,有一定的实际参考价值。     

以制图大赛为契机 全面提升学生的综合创新能力

介绍了近三年全国大学生先进图形技能与创新大赛情况,并以此为契机,优化教学内容、调整教学方式,运用重点突出、方法多样的教学及集中强化训练的方式,全面提升学生的识图和绘图以及综合创新能力,取得了良好的教学效果.     

Laser Doppler Vibrometry: Development of advanced solutions answering to technology's needs

The new trends on Laser Doppler Vibrometry (LDV) development are outlined with particular attention to the innovative solutions answering to the most recent technological requirements which are not met by the current systems.Several LDV application areas are described and the limitations of actual technologies highlighted. The possible solutions needed to overcome these limits are anticipated and emerging technologies which are not completely entered the market but could positively answer to the industrial requirement are described.     

Vibration of circular plate with multiple eccentric circular perforations by the Rayleigh-Ritz method

The free vibration of a circular plate with multiple perforations is analyzed by using the Rayleigh-Ritz method. Admissible functions are assumed to be separable functions of radial and tangential coordinates. Trigonometric functions are assumed in the circumferential direction. The radial shape functions are the boundary characteristic orthogonal polynomials generated following the Gram-Schmidt recurrence scheme. The assumed functions are used to estimate the kinetic and the potential energies of the plate depending on the number and the position of the perforations. The eigenvalues, representing the dimensionless natural frequencies, are compared with the results obtained using Bessel functions, where the exact solution is available. Moreover, the eigenvectors, which are the unknown coefficients of the Rayleigh-Ritz method, are used to present the mode shapes of the plate. To validate the analytical results of the plates with multiple perforations, experimental investigations are also performed. Two unique case studies that are not addressed in the existing literature are considered. The results of the Rayleigh-Ritz method are found to be in good agreement with those from the experiments. Although the method presented can be employed in the vibration analysis of plates with different boundary conditions and shapes of the perforations, circular perforations that are free on the edges are studied in this paper. The results are presented in terms of dimensionless frequencies and mode shapes.     

一种数字频率电压紧急控制装置的设计与实现

介绍了一种频率电压紧急控制装置的设计与实现方法。装置采用32位嵌入式单片机作为核心控制芯片,利用双电压回路进行电压测量,硬件和软件相结合实现频率测量,提高可靠性,确保测量准确。对任一故障的判断和决策都采用多个不同的条件,多重闭锁机制,有效防止误动和拒动;大屏幕液晶实时显示电压、频率等信息。嵌入式双网通信接口,采用国际标准或按用户要求定制通信规约。     

制造加工约束下连续体拓扑优化的数值实现

针对两类常见的制造加工约束即对称性和重复性下的连续体拓扑优化问题,提出了将敏度值在每轮优化前的修正方法,该方法简单且易于编程实现,实现了对称性或重复性约束条件下连续体拓扑优化设计,通过数值算例对不同制造加工约束下的拓扑结果进行了分析对比,结果表明,研究方法具有可行性和有效性。     

Parameter estimation of integrating and time delay processes using single relay feedback test

Autotuning using relay feedback is widely used to identify low order integrating plus dead time (IPDT) systems as the method is simple and is operated in closed-loop without interrupting the production process. Oscillatory responses from the process due to ideal relay input are collected to calculate ultimate properties of the system that in turn are used to model the responses as functions of system model parameters. These theoretical models of relay response are validated. After adjusting the phase shift, input and output responses are used to find land mark points that are used to formulate algorithms for parameter estimation of the process model. The method is even applicable to distorted relay responses due to load disturbance or measurement noise. Closed-loop simulations are carried out using model based control strategy and performances are calculated.     

Analytical mass spectrometry of herbicides

Herbicides are chemical substances that are applied to agricultural soils, gardens, lawns, or plants to destroy or to prevent the growth of undesirable vegetation. The herbicides included in this review are generally synthetic organic compounds that are ingredients in commercial herbicide products that were designated active during late 2002 in the U.S. Environmental Protection Agency's database of registered and canceled pesticide products. The compounds are organized into 21 categories according to their general chemical structures or a common structural group. The herbicides in each category are discussed in terms of their structures, their database electron ionization mass spectra, and their amenability to separation and measurement with gas chromatography, reversed-phase liquid chromatography, and capillary electrophoresis combined with mass spectrometry. Ionization techniques that are considered here are mainly electron ionization, electrospray, and atmospheric pressure chemical ionization. Sixty-six references are provided to herbicide reviews, and to the recent herbicide analytical chemistry and mass spectrometry research literature.     

实体法铣削仿真效率改善及应用算法

轴向切削深度和径向切削宽度是铣削仿真模型求解的几何边界条件,也称为啮合几何参数。根据对啮合参数提取的三类途径的比较,针对直接布尔操作途径仿真效率低的问题,运用集合论描述了实体法铣削仿真中模拟材料去除的布尔运算过程,从时间复杂性角度分析影响实体法铣削仿真效率的因素,提出改善仿真运行效率的4种途径;在此基础上,从几何造型和切削过程两方面给出在仿真计算位置处布尔运算次数由4次减少为1次的可行性分析,提出在简化布尔运算次数情况下的切削几何边界条件的识别和判断算法,对判断算法的有效性和减少布尔运算的时间复杂性进行分析、给出在铣削力仿真中的应用示例,并说明应用范围,从而在保证切削几何边界条件准确提取的同时提高仿真效率,为铣削力等仿真模型的求解奠定基础,推动相关物理仿真研究成果在工程实际中得到切实应用。     

Stochastic models for transfer point location problem

The transfer point location problem has been introduced recently and for the case of minimax objective and planar topology, has only been studied for situations in which demand points are not weighted and have known coordinates. In this paper, we consider the case in which demand points are weighted and their coordinates have bivariate uniform distribution. Also, the problem is developed from a conceptual view and different distance measures are used to make models more applicable in real world situations. The problem is to find the best location for the transfer point such that the maximum expected weighted distance to all demand points through the transfer point is minimized. Depending on assumptions for uniform distributions, two models are considered, convexity conditions are discussed, properties of the optimal solution are obtained and methods to solve the problems are proposed. Finally, numerical examples are given.