试论降低成本的设计技术

一个新产品的功能和成本水平基本上已在产品设计阶段就确定了。研究降低成本的设计技术就是为了给设计师提供一套行之有效的降低和优化成本的辅助设计工具。降低成本设计的技术内涵是与设计过程并行的成本估算、知识基系统的建立和质量及成本的综合优化。论述了各国对此项技术研究应用的状况、技术分析、发展特点和研究前沿的项目及内容 ,如对此技术研究应用的迫切性、对降低成本的最佳时机和产品的全成本概念等的探讨和认识 ;对成本扩展到产品寿命全周期、对目标成本控制法和成本优化设计等的研究和应用。     

浅淡恶劣环境中可控震源的使用方法

本文着重介绍了可控震源的防寒问题以及在复杂地区作业的施工方法.     

电视机监督检验电磁兼容结果分析和对策

本文讨论了电磁兼容对电视机的技术要求和相应对策。     

三峡地下电站变顶高尾水洞水动力特性

在国内首次应用模型水轮发电机组对三峡地下电站变顶高尾水洞方案进行水力过渡过程试验研究。对水轮机导叶实行分段关闭 ,并求出了二段关闭的最佳拐点 ,试验证实了二段关闭对减小尾水管进口的负压和机组转速上升有明显的作用。通过有关水力参数的测试 ,认为变顶高尾水洞可以满足各项技术要求 ,是一个减少山体开挖、节省投资的新型设计方案。在地下电站中具有广泛的应用前景     

EVOLUTIONARY ALGORITHMS WITH PREFERENCE FOR MANUFACTURING CELLS FORMATION

Due to the combinatorial nature of cell formation problem and the characteristics of multi-objective and multi-constrain, a novel method of evolutionary algorithm with preference is proposed. The analytic hierarchy process （AHP） is adopted to determine scientifically the weights of the sub-objective functions. The satisfaction of constraints is considered as a new objective, the ratio of the population which doesn＇t satisfy all constraints is assigned as the weight of new objective. In addition, the self-adaptation of weights is applied in order to converge more easily towards the feasible domain. Therefore, both features multi-criteria and constrains are dealt with simultaneously. Finally, an example is selected from the literature to evaluate the performance of the proposed approach. The results validate the effectiveness of the proposed method in designing the manufacturing cells.     

合成氨扩能改造中锅炉存在的问题及采取的措施

针对天脊集团年产30万t合成氨扩能改造,给2台225t/h高压锅炉带来的除氧器热量过剩、锅炉给水温度升高、主蒸汽温度降低等一系列问题,分析了产生问题的原因,从节约能源、提高锅炉效率考虑,提出了相应的解决问题的办法:利用热量分流、改造省煤器管、增加二级过热器受热面积。经过3年多的生产实践证明,取得了良好的效果。     

The solution of the inverse problem of gravitational potential using a set of measurements of different field elements

A numerical solution of the inverse problem of the gravitational field at a single point is obtained using six field elements for a point, a spherical cap, a differential spherical sector and a vertical segment. In the system of six equations obtained, the unknowns are the mass of the body, the depth of its center, and the second, third, and fourth degree moments. The accuracy of the solution of this system is ten times higher than when using three field elements. __________ Translated from Izmeritel’naya Tekhnika, No. 5, pp. 3–8, May, 2007.     

A new iterative order reduction (IOR) method for eigensolutions of large structures

Order reduction is a computationally efficient method to estimate some lowest eigenvalues and the corresponding eigenvectors of large structural systems by reducing the order of the original model to a smaller one. But its accuracy is limited to a small range of frequencies that depends on the selection of the retained degrees of freedom. This paper proposes a new iterative order reduction (IOR) technique to obtain accurately the eigensolutions of large structural systems. The technique retains all the inertia terms associated with the removed degrees of freedom. This hence leads to the reduced mass matrix being in an iterated form and the reduced stiffness matrix constant. From these mass and stiffness matrices, the eigensolutions of the reduced system can be obtained iteratively. On convergence the reduced system reproduces the eigensolutions of the original structure. A proof of the convergence property is also presented. Applications of the method to a practical GARTEUR structure as well as a plate have demonstrated that the proposed method is comparable to the commonly used Subspace Iteration method in terms of numerical accuracy. Moreover, it has been found that the proposed method is computationally more efficient than the Subspace Iteration method. Copyright © 2003 John Wiley & Sons, Ltd.     

A new distributed approximation algorithm for constructing minimum connected dominating set in wireless ad hoc networks

In recent years, constructing a virtual backbone by nodes in a connected dominating set (CDS) has been proposed to improve the performance of ad hoc wireless networks. In general, a dominating set satisfies that every vertex in the graph is either in the set or adjacent to a vertex in the set. A CDS is a dominating set that also induces a connected sub‐graph. However, finding the minimum connected dominating set (MCDS) is a well‐known NP‐hard problem in graph theory. Approximation algorithms for MCDS have been proposed in the literature. Most of these algorithms suffer from a poor approximation ratio, and from high time complexity and message complexity. In this paper, we present a new distributed approximation algorithm that constructs a MCDS for wireless ad hoc networks based on a maximal independent set (MIS). Our algorithm, which is fully localized, has a constant approximation ratio, and O(n) time and O(n) message complexity. In this algorithm, each node only requires the knowledge of its one‐hop neighbours and there is only one shortest path connecting two dominators that are at most three hops away. We not only give theoretical performance analysis for our algorithm, but also conduct extensive simulation to compare our algorithm with other algorithms in the literature. Simulation results and theoretical analysis show that our algorithm has better efficiency and performance than others. Copyright © 2005 John Wiley & Sons, Ltd.     

基于神经网络的智能过滤系统的研究与设计

首先对现有的网络安全隐患和现有的关于安全过滤方法作了简单介绍,提出现有网络过滤技术的不足,接着提出利用信息检索、人工智能和遗传算法相结合的技术,能有效提高网络过滤的性能.