浏览器中使用Xquery

<正>现在,浏览器已经不再是一个简单的浏览引擎,它已经发展成了一个完备的程序平台。在几种不同的在浏览器中嵌入程序的方法中,最流行的一个要数JavaScript。其他的方法包括Flash,Java Applets,Google Web Toolkit等。在这里,我们继续这种使用服务器端编程语言进行客户端编程的意图,不过我们不再讨论使用Java,而是使用XQuery家族。XQuery是专门针对XML的查询和控制语句,同时它也适用于HTML。     

第二代Web语言(VRML)的发展及其应用

本文简要阐述了第二代Web语言 (VRML)的发展及其特点 ,同时论述了VRML如何通过Script节点或EAI接口与Java语言有机结合来编程以及VRML编程环境和运行平台 ,最后介绍了VRML的应用及发展前景。     

Web3D技术及其在工程图学教学中的应用

在工程图学远程教学系统开发中,多媒体素材的制作是至关重要的,研究并运用先进的开发技术和开发工具,可以更好地满足工程图学远程教学系统中对多媒体素材的网络化、三维形象化、强交互性等功能要求。为此,文章研究了Web3D技术的基本概念、Web3D实现技术及典型的开发工具,并以实例的方式详细阐述了VRML、JAVA、Cult3D等Web3D技术在工程图学教学中的应用。该技术在远程教育和教学领域中具有重要的现实意义。     

运用CAXA电子图板解决CNC车床编程中的难点问题

通过对计算机数控车床手工编程常见难点问题的分析，提出了利用CAXA电子图板软件的绘图、编辑、工程标注、坐标查询等功能直观形象地提高数控编程精度、效率和工艺合理性的新方法。阐述了CAXA电子图板在数控工艺处理、图形数学处理、刀具干涉分析、编写数控程序、校验调试与仿真运行数控程序等编程阶段的应用技巧和应用特点，并通过编程实例予以详细说明。     

浅议数控车床编程的工艺处理及优化

介绍在编写程序前,编程人员必须对加工工艺过程、工艺路线、刀具切削用量等进行正确、合理地确定和选择,强调工艺处理是数控编程中的关键,并提出在保证数控加工的质优,高效等要求下,优化数控编程程序。     

仿真软件在数控编程教学中的应用

数控编程是数控专业的主干课程,数控编程是数控专业的一门基础课,教学中学生感到非常抽象,编程技术难以提高,为此在教学模式,教材编排及教学方法上做一些探索。提高教学质量是数控编程课程改革面临的难题,改革的最佳途径就是充分发挥实体仿真软件在数控编程教学中的应用。     

浅析项目教学法在JAVA编程教学中的应用

我国高等院校计算机Java编程语言教学尚存在很多问题,针对Java语言程序设计,提出项目教学法,以此来解决学生的计算机技能难题,提高学生对Java语言的学习掌握与编程的综合素质能力。     

数控铣床加工工艺的探讨

数控铣床在机械加工和模具制造业应用非常广泛,数控编程工艺又是数控铣床编程加工过程中很重要的环节,本文将针对数控铣床编程加工工艺的特点及其工艺步骤进行阐述。     

基于UG的数控编程关键技术研究

数控技术是制造业信息化的关键技术之一,数控加工是现代制造的重要组成部分。随着计算机技术的飞跃发展,数控编程由手工编程发展到自动编程。本文对自动编程软件及其工作过程进行了介绍,以UG软件为例描述了自动编程软件在数控编程与加工中所发挥的重要作用。     

数控编程KBE系统的基础性使能技术研究

针对数控编程领域知识的特点,对KBE系统实现的基础性使能技术进行了研究,介绍了基于实例和规则的数控编程领域知识表示方法和知识获取的概念、途径及过程,阐述了CBR在复杂零件数控编程中的应用,提出了以人工知识获取为主、机器学习为辅的数控编程领域知识获取方式和基于双向混合推理控制策略的CBR／RBR集成数控编程领域知识推理方法,研究成果在开发的原型系统中得到了应用,证明方法可行．     

Design, development and testing of a turning dynamometer for cutting force measurement

In this study, a turning dynamometer that can measure static and dynamic cutting forces by using strain gauge and piezo-electric accelerometer, respectively, has been designed and developed. The orientation of octagonal rings and strain gauge locations has been determined to maximize sensitivity and to minimize cross-sensitivity. The developed dynamometer is connected to a data acquisition system. Cutting force signals were captured and transformed into numerical form and processed using a data acquisition system consisting of necessary hardware and software running on MS-Windows based personal computer. The obtained results of machining tests performed at different cutting parameters showed that the dynamometer could be used reliably to measure cutting forces. Although the dynamometer was developed primarily for turning operations, it can be used to measure cutting forces during nearly all machining operations (milling, drilling, etc.).     

Velocity-controlled shape-tracing system using eight opticalsensors

A novel two-dimensional shape-tracing system was developed that uses eight optical sensors and two stepping motors. Each optical sensor, which consists of an optical fiber and a Darlington phototransistor, senses the intensity of the reflected light from drawings to determine the motion pattern of stepping motors. A software velocity-control scheme was also considered, because the shape-tracing system was designed mainly for an automatic plasma arc cutting process. By programming the control software in assembler language, a maximum pulse frequency of 2000 pulse/s, which is equivalent to a 4.8-m/min linear velocity, could be attained in the developed system. The developed shape-tracing system can be applied not only for the plasma arc cutting process, but also for other shape-tracing processes, such as for cutting clothes     

Numerical and Experimental Approach of Cutting Temperatures to Green Turning of 42CrMo4 Steel

In the present contribution, experimental and numerical methods concerning orthogonal cutting are proposed in order to study the thermal phenomena accompanying the turning process of 42MoCr4 alloyed steel with respect to cutting parameters (depth of cut, feed rate, and cutting speed), such as cooling-lubrication method. Two environment-friendly cooling techniques (near dry cutting and dry cutting) and for comparison reasons conventional flood cooling have been considered. For experimental validation, series of tests are carried out concerning cutting temperature measurement close to the cutting zone. The influence of cutting conditions on the cutting temperature has been analyzed using Design Expert software. Additionally, for the dry cutting tests, numerical simulation of thermal phenomenon have been performed using DEFORM 2D software. Comparison of numerical results concerning cutting temperature to experimental ones shows a very good coincidence.     

A DYNAMIC PROGRAMMING APPROACH TO THE ECONOMIC DESIGN OF X-CHARTS

Recent technological advances have rendered dynamic process control a viable alternative. A dynamic programming approach is proposed for the modeling and cost minimization of statistical process control activities. The decision parameters of the control chart are allowed to change dynamically as new information about the process becomes available. This general approach has been known as a theoretical possibility for many years, but its practical performance is explicitly investigated in this paper. It is shown with numerical examples that the dynamic programming solution can be much more economical than the conventional static solution with fixed control chart parameters. The substantial potential cost savings and the feasibility of a dynamic control procedure suggest that dynamic process control should replace standard statistical or economic design of control charts as the preferred method in automated production processes.     

Numerical implementation of the S-matrix algorithm for modeling of relief diffraction gratings

A new numerical implementation is developed to calculate the diffraction efficiency of relief diffraction gratings. In the new formulation, vectors containing the expansion coefficients of electric and magnetic fields on boundaries of the grating layer are expressed by additional constants. An S-matrix algorithm has been systematically described in detail and adapted to a simple matrix form. This implementation is suitable for the study of optical characteristics of periodic structures by using modern object-oriented programming languages and different standard mathematical software. The modeling program has been developed on the basis of this numerical implementation and tested by comparison with other commercially available programs and experimental data. Numerical examples are given to show the usefulness of the new implementation.     

Manipulator motion planning for high-speed robotic laser cutting

Recent advances in laser technology, especially the increase of the cutting speed, has motivated the amendment of the existing robot path methods, which do not allow the complete utilisation of the actuator capabilities and neglect certain particularities in the mechanical design of the wrist of the manipulator arm. This research addresses the optimisation of the six-axis robot motion for continuous contour tracking while considering the redundancy caused by the tool axial symmetry. The particular contribution of the paper is in the area of multi-objective path planning using the graph-based search space representation. In contrast to previous work, the developed optimisation technique is based on dynamic programming and explicitly incorporates verification of the velocity/acceleration constraints. This allows the designer to define interactively their importance with respect to the path-smoothness objectives. In addition, this optimisation technique takes into account the capacity of certain manipulator wrist axes for unlimited rotation in order to produce more economical motion. The efficiency of the developed algorithms has been carefully investigated via computer simulation. The presented results are implemented in a commercial software package and verified for real-life applications in the automotive industry.     

Optimal selection of machining rate variables by geometric programming

The selection of economically optimal machining rate variables, i.e. cutting speed and feed rate, is of major importance in the field of metal cutting.

In this paper, apart from the conventional methods used for optimization in machining economics, geometric programming, a relatively new non-linear programming technique, is employed to optimize the constrained unit cost problem in turning. The cutting power available from the machine tool and the permissible CLA value of surface roughness are used as the forced constraints in the primal programme.

Initially, the primal and dual programmes are formulated. Furthermore, a numerical example is presented to illustrate the application of geometric programming which has been proved successful.

It is pointed out that geometric programming may be also used for optimization of unit cost in machining processes other than turning under the assumption that the imposed restrictions, discussed in this paper, are valid.     

The features of fracture of heterogeneous materials and frame structures. Potentialities of MCA design

A new promising numerical method named movable cellular automata (MCA) is described. Because this approach is based on the discrete concept, in contradistinction to FEM-based software, the software based on the MCA concept has a few clear advantages. The main one is connected with modeling of real fracture process. The MCA method has been successfully used for modeling dynamic loading of heterogeneous materials and structures. The results of simulations agree closely with the experimental data. The results show that the MCA approach could be really useful to solve a lot of civil engineering problems from materials to constructions. Special software has been developed on the basis of this method. Due to its potentially unique abilities, the MCA method could be considered as a breakthrough in numerical techniques and a new tool of engineering mechanics.     

Modelling of axis feed consumed energy for sustainable manufacturing

The accurate evaluation of electrical energy demanded by a CNC toolpath during a machining process is essential to determine its efficiency. Actually, the dynamic behavior of cutting forces seems to be neglected by investigators despite its influence on the consumed cutting energy during a face milling operation. This paper aims to investigate the effect of dynamic behavior of the machining system in order to take into account the dynamic response of the cutting forces on the axis feed power prediction. A dynamic cutting power model is developed in order to predict the consumed cutting energy. A parametric study is performed in order to show the impact of cutting conditions on the consumed energy values. The numerical results are compared to experimental ones.