Foreword

Reliable Computing -     

一种新的传导型共模/差模EMI分离测试网络

传统的传导型电磁干扰（EMI）噪声的测试多为混合测试或分时分离测试，由于共模和差模EMI噪声没有完全分离或不为同～时刻的值，因此其测试结果不够精确。本论文针对传导型共模、差模EMI噪声产生机制的不同，给出了一种可同时测量共模／差模噪声的分离测试网络，该分离测试网络基于一种简单的测试等效电路。本文给出了该分离测试网络的电路原理及仿真结果。仿真结果表明该分离测试网络的分离测试效果良好。     

欧洲和德国的钢铁工业的环保现状和发展(一)

欧洲钢铁工业的环境保护已经达到了很高的水平.20世纪60年代初,保护环境一般认为只是局限于限制工业对人们的影响.现在,尤其是在罗马协议(Club of Rome)的努力之下,环保的范围从节约资源延伸到整个自然环境的保护,而后产生了目前应用中的工业过程和产品生产周期.整体来说,保护环境的所有途径都被视为是未来平衡发展的先决条件. 欧盟环境保护技术的情况可以德国为例,更准确地说是杜伊斯堡的蒂森克虏伯钢厂(ThyssenKrupp Stahl AG),其粗钢产量约占德国总产量的35%. 钢铁工业环境保护的重点仍然是维护空气质量,在此目的下,进行除尘处理.由烟囱处取样获得目前的除尘水平来看,今后的除尘主要是控制粉尘扩散和减少细小微粒的排放. 钢铁工业环境保护的关键策略就是循环利用,它能起到与环境协调一致的作用,能够解决相关工艺中需要的大量的原料问题.德国的蒂森克虏伯钢厂(ThyssenKrupp Stahl AG)现在炉渣的综合回收率水平已接近95%,其中冶金渣的回收利用率尤为突出.在德国,高炉渣利用率达到了100%,同时炼钢渣的利用率也超过了90%,每吨粗钢的耗水量也控制在100 m3的范围内.大量的努力不仅保证了有效的回收和再生利用工序,而且冷却水的利用也保证了新水的补充率降低到每吨粗钢15m3左右. 污染控制除与主要环境即空气、水和土壤有关外,已扩展到回收过程再利用的水平,更多地重点渐渐地放到相关产品的环境保护.产品和原料却日益受到生产商和消费者的重点检验,有点与环境协调性标准相反.组织机构的环境保护手段包括环境管理系统的认可、生态平衡、政府部门的自愿协议以及提高公众的信息、教育水平. 欧洲的钢铁工业,当然也包括德国,都已经意识到环境保护的重要性同工业研究与开发的重要性处于同等地位.一个典型的例子就是超薄板汽车用钢项目,这个与产品相关的研究引入了35家合作厂商共同研究一个比目前传统的汽车车身更结实、更轻的项目.欧洲钢铁厂家的联合合作已经成功研究出应用于烧结厂的减少二恶英(dioxin)排放物的吸收工艺.用褐煤焦尘作为吸附剂,已能够平均减少排放物大约70%.很可能2003年在杜伊斯堡的ThyssenKrupp Stahl AG将被授权建全世界最先进的焦化厂.在这个项目过程中研究出的主要部分成果,例如低尘低烟煤湿熄法和减少PAH排放物的单室压力控制系统,会恰当地应用于新的工厂.另一个主要进步是ThyssenKrupp Stahl AG研制的Hamborn OxiCup竖炉,它有湿法冶炼和排除含铁残渣的功能.此技术预计成为回收利用铁水和钢产品中产生的粉尘和泥浆这一难题的解决方案. 德国的局势尤其显示出环境法规的落实正开始对经济发展和劳动力市场起到不利影响.盛行的经济技术条件需要合法的体制治理环境保护的合理化.将来任何进一步的措施都要考虑这一事实,既要获得可持续发展,又要考虑到经济发展和社会需求.     

Optimal Ordered Problem Solver

We introduce a general and in a certain sense time-optimal way of solving one problem after another, efficiently searching the space of programs that compute solution candidates, including those programs that organize and manage and adapt and reuse earlier acquired knowledge. The Optimal Ordered Problem Solver (OOPS) draws inspiration from Levin's Universal Search designed for single problems and universal Turing machines. It spends part of the total search time for a new problem on testing programs that exploit previous solution-computing programs in computable ways. If the new problem can be solved faster by copy-editing/invoking previous code than by solving the new problem from scratch, then OOPS will find this out. If not, then at least the previous solutions will not cause much harm. We introduce an efficient, recursive, backtracking-based way of implementing OOPS on realistic computers with limited storage. Experiments illustrate how OOPS can greatly profit from metalearning or metasearching, that is, searching for faster search procedures.     

Instance-Based Regression by Partitioning Feature Projections

A new instance-based learning method is presented for regression problems with high-dimensional data. As an instance-based approach, the conventional method, KNN, is very popular for classification. Although KNN performs well on classification tasks, it does not perform as well on regression problems. We have developed a new instance-based method, called Regression by Partitioning Feature Projections (RPFP) which is designed to meet the requirement for a lazy method that achieves high levels of accuracy on regression problems. RPFP gives better performance than well-known eager approaches found in machine learning and statistics such as MARS, rule-based regression, and regression tree induction systems. The most important property of RPFP is that it is a projection-based approach that can handle interactions. We show that it outperforms existing eager or lazy approaches on many domains when there are many missing values in the training data.     

Are Reviews an Alternative to Pair Programming?

From the first presentation of extreme programming on, pair programming has attracted a wide range of programmers to work together in front of one display. The proposed advantages of pair programming are a faster development cycle and code with higher quality. However, the nearly doubled personnel cost when compared to single developers seems to outweigh these advantages. Instead of showing the superiority of pair programming, we seek an alternative. Can a single developer be assisted by an already known technique with which he produces the quality of pairs with only a fraction of the cost? The answer with some restrictions is: yes, he can. Reviews are a reasonable candidate with respect to code quality and cost.     

Structure generation and performance comparison of elliptic Gm‐C filters

Starting from a set of matrices describing a general G_m‐C filter topology, a procedure is developed for generating structures of lowpass filters. As the matrices and the filter topologies have a one‐to‐one correspondence, an algebraic method is used to identify filter topologies with desired properties, here, transfer functions with finite jω‐axis transmission zeros, specifically elliptic filters. Sensitivity expressions for these structures are derived and a performance comparison based on a set of chosen criteria is made. For a specified elliptic transfer function, filters with only grounded capacitors and those containing also floating capacitors emerge as alternative realizations, as are filters with a single input and those with distributed inputs. For third‐order functions, a detailed comparison is performed of leapfrog (LF) and inverse follow‐the‐leader‐feedback (IFLF), the most popular special cases, and of topologies that have also floating capacitors (LF_f, IFLF_f), as well as of a novel configuration that uses also distributed inputs (DI_f) and leads to a reduced element count. Design guidelines and restrictions are given, which follow from the derived results with focus on the circuits' sensitivity performance and other properties important for IC implementation. Copyright © 2004 John Wiley & Sons, Ltd.     

Sliding performance of polymer composites in liquid hydrogen and liquid nitrogen

Outstanding features favour the application of polymers and polymer composites in low-temperature technology. The booming hydrogen technology is a challenge for these materials, which are considered as seals and bearings in cryogenic pumps. In the present study, three types of thermoplastics, i.e., polyetheretherketone (PEEK), polyetherimide (PEI) and polyamide 6,6 (PA6,6), and one epoxy were considered as matrix materials. Micron-sized fillers, i.e., short carbon fibres, graphite flakes, and PTFE powders, were incorporated into these polymers together with nano-sized TiO₂ particles. Optimised compositions of each matrix were selected from our previous works at room temperature in order to be studied at very low temperature conditions. In particular, frictional tests were carried out with polymer composite pins against polished steel surfaces under constant load over a certain distance in liquid hydrogen and liquid nitrogen. Afterwards, worn surfaces were analysed by using scanning electron microscopy (SEM). It was found out that the tribological properties in liquid hydrogen are dominated by the matrix materials, in particular thermoplastics perform generally slightly better than thermosetting resins.