宏蜂窝模型的传播模型校正研究

详细介绍了 宏蜂窝传播模 型校正的基本操作流程 结果分析及注意事项 对工程 ,人员了解和开展模型校正工作有一定的指导作用 。     

软交换技术发展现状

介绍了国际软交换技术的现状，采用软交换技术的下一代网络提供的业务，从事软交换研究的国际组织及软交换技术发展中存在的问题。     

Parallel multilevel fast multipole method for solving large-scale problems

The Multilevel Fast Multipole Method (FMM) is a well-established method and can be applied to solve electromagnetic (EM) scattering problems. Compared with other traditional methods, it requires less computational time and memory. However, constrained by a single processor's speed and memory limitations, the problem size that can be solved by serial implementation is still relatively small. For a million-unknown target, the computational time on a single processor is intolerable, and memory could be easily exhausted. Parallel-computing technology, which can utilize multiprocessors, provides an efficient way to solve electrically large-scale EM problems. This paper will focus on discussing the parallel methodologies applied to a multilevel FMM code, as well as demonstrating the computational efficiency of the parallel approach.     

工程咨询要为节约资源能源尽责

在经济发展中,如何应对资源短缺的挑战已经是一个世界性课题.在世界各国,节约和开发利用可再生能源已经成为一种潮流,不少国家的资源保护意识已经融入了生活中的每一个细节,甚至一些国民消费水平居高的资源大国,都在锱铢必较地节约资源和能源.     

Grain refinement of Al-7Si alloys and the efficiency assessment by recognition of cooling curves

Under sand cup solidification condition, the influence of Ti, B concentration, and holding time on the grain size of a high-purity Al-7Si alloy has been systematically studied. It is found that the grain size decreases rapidly at lower Ti or B additions, and is almost constant at the higher concentrations. For Al-3B refined Al-7Si alloys, the grain size increases at the initial period of holding time, and then rapidly becomes independent of holding time; while for Al-7Si alloys refined with Al-5Ti-1B, the grain size increases with holding time throughout. To evaluate the refinement efficiency, a new method named “intelligent evaluating of melt quality by pattern recognition of thermal analysis cooling curves” has also been introduced in this article. The results show that comparing the cooling curve of the evaluated melt with those in a database to find the most similar one to it can precisely assess the grain refinement efficiency of the measured Al-7Si alloy. In addition, the influence of Ti, B addition levels, and pouring temperatures on some characteristic parameters of cooling curve has also been discussed.     

Traveling-wave piezoelectric linear motor Part I: the stator design.

A new type of piezoelectric linear motor incorporating a traveling wave has been developed. The linear motor is comprised of a stator and a carriage. The stator design, which consists of a meander-line structure and gear teeth mounted on the meander-line structure, is the focus of this article. The meander-line structure is constructed with bimorph actuators arranged in a line. These actuators are driven by two phased sets of alternating current (ac) in order to generate a traveling wave. The traveling wave is transferred to the gear teeth, by which the carriage is driven. Modeling of the stator is derived by use of a strain energy method. The performance of various materials is evaluated by analytical and experimental methods. The analytical and the experimental results are quite approximate. Modal analysis is investigated using ANSYS. Appropriate modes associated with ultrasonic levels of resonant frequency are selected to obtain desired motion and to enhance the output performance. Surface speed for various applied input voltage are studied and indicate a nearly linear relationship. The stator in combination with the carriage makes up the linear motor.     

Improving Cost Estimates of Construction Projects Using Phased Cost Factors

Central to cost-based competition is the capability to accurately predict the cost of delivering a project. Most literature on cost estimation focuses on specific estimation methods as generic techniques and little attention has been paid to the unique requirements at each project stage. This note attempts to identify the critical factors for effective estimation at various stages of typical construction projects. Drawing from organization control theory and cost estimating literature, this note develops a theoretical framework that identifies the critical factors for effective cost estimation during each project phase of a conventional construction project. The underlying logic is that as a cost estimating effort progresses, both task programmability and output measurability improve. As a result, control effort will shift from input-oriented control to a combination of output and behavior control.     

特低渗油藏渗流特征及增产技术研究

从特低渗储层渗流机理研究出发，分析了其渗流规律——非达西渗流特征；根据储层中上覆岩石围压变化，通过室内试验表述了其对渗透率伤害。研究提出了改善渗流特征的注水条件、井网优化和压裂对策，可以有效提高这类油藏的开发效果。     

Coordinating production and distribution of jobs with bundling operations

We consider an integrated scheduling and distribution model in which jobs completed by two different machines must be bundled together for delivery. The objective is to minimize the sum of the delivery cost and customers' waiting costs. Such a model not only attempts to coordinate the job schedules on both machines, but also aims to coordinate the machine schedules with the delivery plan. Polynomial-time heuristics and approximation schemes are developed for the model with only direct shipments as well as the general model with milk-run deliveries.