SYNTHESIS OF CHEMICAL REACTION PATHS: ECONOMIC AND SPECIFICATION CONSTRAINTS

The synthesis of alternative reaction paths leading to a desired chemical has received increasing attention in the recent past. A procedure to develop new reaction schemes in a systematic manner was reviewed by the authors ( [ 1 -3] ). The algorithm presented in these earlier papers implied the generation of an infinite number of reaction paths. The thermodynamic feasibility is a preliminary screening which reduces the number of chemical production schemes. Further screening is necessary, taking into account considerations which are related to economics, processing, safety and so on. Some constraints related with role specification, gross added value and demand/supply requirements are analysed in this paper. Examples illustrate the application of the screening procedure, showing that the addition of a few constraints results in a dramatic decrease of alternative reaction paths.     

颗粒增强TiAl基复合材料及其Si的韧化作用研究EI

运用ＸＤ工艺制备了颗粒增强ＴｉＡｌ基复合材料。增强颗粒均匀分布于ＴｉＡｌ基体中并细化ＴｉＡｌ合金。通过在ＴｉＢ_２／ＴｉＡｌ、ＴｉＣ／ＴｉＡｌ复合材料中加入适量的Ｓｉ，颗粒增强ＴｉＡｌ基复合材料的室温延性得到了改善。     

The computer — a new tool for visual art

The article points out some new possibilities for using computers as an instrument for visual art, especially stressing the mathematical method of picture synthesis. It is illustrated with results of recent computer art by Herbert W. Franke and Horst Helbig.     

凸轮-连杆组合机构的优化设计

以最大压力角为最小做为优化目标，并采用坐标轮换法和黄金分割法等优化方法对书本打包机中的推书机构（凸轮－连杆组合机构）进行优化设计，从而使得机构确保运动的平衡性的前题下具有良好的传力性能，使设计结果更加合理。     

GTL 工艺技术评述

介绍了1990年以来GTL工艺技术开发的进展情况，其中以Sasol-SSPD和Syntruleum两种工艺最受关注，从现有数据分析。Syntruleum虽采用含氮合成气生产工艺，但并未使装置的单位投资明显改善，因此，近10年来GTL工艺技术开发虽取得了长足的进步，但其装置投资仍偏高，从而又严重影响了产品成本，按南非Sasol公司的经验。开展资源综合利用是降低液体燃料生产成本的有效途径，目前国外GTL工艺技术的开发仍很活跃，我国也已形成大量实验室成果。建议尽快组织力量完成工业性试验。     

连拱坝交叉模态综合法的完备性

对笔者提出的连拱坝动力特性计算的子结构交叉综合法的正确性进行了证明．利用证明子结构子模态向量组成的线性空间是完备的基础上，说明当交叉子结构中所取的截尾模态趋向于完备时，其结果等同于整体计算，并表明近似计算将收敛于正确的结果．     

Synthesis and Properties of the Bi-Based Superconducting Powder Prepared by the Pechini Process

Bi-based superconductors are of great interest in high-temperature superconductors. We describe what is believed to be the first synthesis of these materials using the Pechini process, a low-temperature synthetic method that often yields inorganic oxide of excellent phase purity and well-controlled stoichiometry. Using this process, it has been possible to synthesize phase-pure Bi-2223 phase by calcining the appropriate polymeric precursors in air at 800°C for several hours. The superconductivity studies show that the Pechini-synthesized materials appear to offer high-quality performance.     

最佳相位设计的MBE声码器语音合成

提出了一种基于最佳相位设计的语音合成技术,能够有效降低MBE声码器合成语音信号由于波形失衡而导致的饱和失真的概率.此外,为了保证合成滤波器的稳定性,对线谱频率(LSF)系数提取进行了优化.实验结果显示,合成语音信号波形近似平衡地分布在零幅度值的上下,语音听起来没有不舒服的感觉.实验结果表明,基于最佳相位设计的语音合成技术能够有效改善合成语音质量.     

Poetry I: Teaching verse with CAI

The teaching of literature through CAI raises problems of both a linguistic and instructional nature; student involvement and creativity in studying literature, and especially poetry, is difficult to build into a computer-based lesson. We have confronted these difficulties in the lessonPoetry I, which introduces undergraduates to basic concepts of poetic verse in a design using screen display, speech synthesis, and verse processing to maximize interactivity and student involvement.The lesson contains instructional modules which include the student's composition of a limerick. Computational processing of the limerick's text enables the program to offer guidance as the student composes and revises the verse and gains first-hand experience with metrical language. The significant problems inherent in processing verse are addressed by adapting Digital Equipment Corporation's DECTalk speech synthesizer as an engine converting natural language verse text into accessible strings of phonemic symbols. Although the verse processor cannot scan verse, it can interpret DECTalk's symbols reliably enough to successfully stimulate students' thinking about their verse compositions.Preliminary responses to the program have been favorable and demonstrate its effectiveness in involving students more deeply in learning about poetic verse. This suggests that the techniques of verse processing prototyped inPoetry I might be usefully extended to other types of verse and levels of study.W. Webster Newbold is an Assistant Professor of English at Ball State University, Muncie, Indiana, USA, who has recently served as English Department Computer Coordinator. His research interests include computer-assisted instruction and computer-based composition.Herbert F. W Stahlke is a Professor of English, specializing in linguistics, and currently serves as Associate Director for Academic Computing, Ball State University Computing Services. His research interests include computer-assisted instruction, natural language processing, and lexical databases.