全球3G市场管制政策分析

主要对各国3G许可证与使用技术标准的抽绑政策．各国对2G／3G网络漫游的管制规定。以及3G网络之间共享的种类及实施方式等方面做了详尽的讲解，并进行比较和分析。     

全球宽带电话市场分析

近两年．IP电话又叫网络电话的发展受到全球的关注。随着宽带接入的发展，基于宽带接入提供的网络电话具有了更大的生命力。从宽带电话的经营模式出发，探究这类业务的出现时现有话音业务市场的影响，进而分析这类业务的发展前景。     

UHF频段卫星移动通信系统若干问题的探讨

本文根据我国陆海空移动用户的需求与特点，借鉴国外经验，提出了建设ＵＨＦ频段卫星移动通信系统的建议；对照已建成的Ｃ波段卫星固定通信系统，分析了其优缺点；最后深入探讨了应用中的若干技术问题。     

Computer Aided Tolerance assignment

Tolerances are basic to the production of every part. This is because perfect parts cannot be produced with existing processes and machines. The determination of tolerances for the individual parts of a functional assembly is critical, but not trivial. Numerous approaches are suggested in past literature for (analytical) tolerance allocation. With the advent of total automation, more attempts are being made to computerize manual design tasks. Tolerance design, assignment and allocation can also be fully automated if the assembly function can be estimated by the computer.

In the present paper, an attempt is made to computerize tolerance assignment. A simple example of a two piece assembly, viz., a fit, is used to demonstrate the developed methodology. A feature extraction is first performed from both detail and assembly drawings. Then, probable assembly interfaces are determined using a rule based procedure. Consequently, tolerances are assigned to the basic dimensions of each feature and to the assembly interfaces using a tolerance database and user interaction. More complex analysis for tolerance allocation is also under study.     

Applying the critical path method to manufacturing routing

Traditionally the critical path method (CPM) has been used primarily as an a'priori planning and scheduling device. Its applications have typically been limited to one-shot projects, usually with a long period of completion time. This paper proposes taking these ideas to continuous production systems, and to implement the CPM not just at the outset but throughout the process. The algorithm calls for repeatedly calculating the critical path through the production process and routing parts so as to remain off this path. Before the model is presented, some basic ideas are introduced from group technology (GT) and CPM. After the presentation of the model, two potential implementations with the usage of computer are proposed.     

Applying CIM technology to image factories

Image processing allows the automation of the business transaction, turning “paper factories” into “image factories.” This burgeoning new area of computerization needs new paradigms, theories, and methods to maximize its effectiveness at cutting time and costs. This paper investigates what this new area of computerization can gain from CIM technology. It examines the similarities between the processing of computer images in a paperless business environment and the processing of materials into products in the manufacturing plant. These similarities will allow us to apply mature, well-tested CIM techniques to emerging image factories.     

Magnetohydrodynamic stability of boundary layers along a flat plate with pressure gradient

Summary The purpose of the paper is to consider theoretically the characteristics of steady two-dimensional magnetohydrodynamic boundary layer flow past a flat plate with pressure gradient in the presence of transverse magnetic field and its stability problem. The boundary layer equation is transformed into a non-similar one and numerical solutions are obtained by the difference-differential method. The neutral stability curves for wavelike disturbances of Tollmien-Schlichting type are then presented for the velocity profiles obtained above. Numerical results for the magnetic parameter and pressure gradient parameter are given for the velocity profiles, coefficient of skin friction, displacement thickness and the critical Reynolds number.With 10 Figures     

高油价下我国石油化工的发展对策思考

改革开放20多年来，中国经济向全球展示了持续快速的增长，作为支柱产业的中国石化工业也一直保持着良好的增长势头，得到了稳定快速的发展，尤其在“十五”期间，中国的石化工业在世界石化业中的地位有了突破性的提升。