层状催化剂颗粒的优化设计——双组分等温平行反应体系

针对双组分等温平行反应体系,分析讨论了以提高催化剂活性和选择性为目标时催化剂活性组分的最优分布形式(为δ-函数分布),并给出了确定这种反应体系的催化剂的最佳活性层位置的计算方法。结果表明:以提高选择性为目标的最佳活性层位置比以提高活性为目标的要更靠近催化剂核心,实用的最优位置应介于二者之间。最后,本文还研究了反应动力学级数、本性选择性以及内扩散模数(Thiele 模数)等因素对最佳活性层位置的影响。     

Properties of titanium-containing sol-gel films modified with copper and vanadium oxides

Translated from Steklo i Keramika, No. 1, pp. 4–6, January, 1994.     

Speed reduction on through roads in Nordrhein-Westfalen.

The paper describes a program of experiments for speed reduction on 28 through roads in Nordrhein-Westfalen. In the process, different measures of construction, design, and traffic control were examined to determine their usefulness to reduce speed and to improve road safety. The need for systematic evaluation of a catalogue of measures partly resulted in unsatisfactory design conceptions for the through roads. The evaluation of the effects of the program has been carried out by use of before-and-after-studies of large extent. The speed measurements show that a distinct speed reduction can be obtained only from selected physical improvements. Measures based on optical effects and traffic signs were found to have very little effect on vehicle speeds. Furthermore, in light of the relatively small number of accidents that occur on the selected facilities, it was not possible to establish the beneficial impact of each specific control measure with statistical certainty. However, the results of the experiment have had an influence on the current definition of new design standards for main urban streets in Germany.     

Crystallization behaviour of Ni-Co-base metallic glasses by isochronal and isothermal annealing

The crystallization behaviour of three amorphous alloys, Co₅₀Ni₂₅Si₁₅B₁₀, Ni₅₀Co₂₅Si₁₅B₁₀ and Ni₅₀Co₂₅P₁₅B₁₀, was studied by means of differential thermal analysis in conjunction with scanning transmission electron microscopy. Isochronal annealing showed a strong dependence of crystallization on scan rate over the range of 1.99 to 20.70 K min^–1. At high Co/Ni ratios, a sequential two-stage crystallization process involving primary MS-I phase followed by MS-II phase precipitation was observed. At low Co/Ni ratios MS-I and MS-II crystallization were concurrent and inseparable. Replacement of the metalloid Si with P as the glass-former dramatically reduced the activation energy for crystallization as well as the crystallization temperature. A mechanistic understanding of these findings was pursued in light of TEM/STEM microanalysis     

Two-level optimal output feedback stabilizer design

The paper addresses the design of two-level power system stabilizers using an optimal reduced order model whose state variables are torque angles and speeds. The reduced order model retains their physical meaning and is used to design a two-level linear feedback controller that takes into account the realities and constraints of electrical power systems. The two-level control strategy is used, and a global control signal is generated from the output variables to minimize the effect of interactions. The effectiveness of this controller is evaluated and a multimachine system is given as an example to illustrate the advantages of the proposed method. Responses of the system with a two-level scheme and an optimal reduced order scheme are included for comparative analysis.