制备2，4－二氯－5－氟苯甲酰乙酸甲酯的缩合剂及工艺研究

通过３种不同的碱来制备２，４－二氯－５－氟苯甲酰乙酸甲酯，优选得到了其最佳缩合剂甲醇钠；同时应用正交设计实验，研究了原料配比、反应时间、反应温度对收率的影响，在优选条件下收率为７８．５％。     

FAST MEASUREMENT OF ASH CONTENT IN COAL WASHING PLANT

The coal filter cake is a product of fine coal after floatation which has an ash content of 7-13%, water content of 30±2%, and a particle size of less than 1 mm. The ash content was measured by the intensity of the single backscattered gamma-ray, and its accuracy is mainly dependent on the energy of the gamma-ray. The 238Pu low energy photon source is selected in this work. The energy of its gamma-ray is 15 keV, which can result not only in the best sensitivity, but also in the lowest contribution to the environment radiation. The root mean square deviation of the ash measurement is±0.33% (±1σ).     

Improved fully-balanced current-mode integrator

A high CMRR fully-balanced current-mode integrator structure is presented. The proposed structure improves the CMRR at low frequencies by a factor of g_m/g_o. Moreover, the structure provides more flexibility to guarantee stability and is significantly less sensitive to process mismatches. The differential and common-mode gains and CMRR at low and high frequencies are analysed as well as verified in simulation     

A new method for calculating loss coefficients [of power systems]

A method is proposed which avoids many limitations associated with traditional B-coefficient loss coefficient calculation. The proposed method, unlike the traditional B-coefficient method, is very fast and can handle line outages. The method utilizes network sensitivity factors which are established from DC load flow solutions, Line outage distribution factors (ODFs) are formulated using changes in network power generations to simulate the outaged line from the network. The method avoids the use of complicated reference frame transformations based upon Kron's tenser analysis. The necessity of data normalization used in least squares and the evaluation of the slope of &thetas;_j versus PG_n is not necessary with the proposed method. Using IEEE standard 14-bus and 30-bus systems, the method's results are compared against results obtained from an AC load flow program (LFED). The method's solution speed is compared to that of the LFED method, the base case database method and the conventional B-coefficient method based on A_jn-factor. The proposed method is easy to implement and, when compared to other methods, has exhibited good accuracy and rapid execution times. The method is well suited to online dispatch applications     

Analysis of dinosaur samples by nuclear microscopy

Several dinosaur bone and eggshell fossil samples unearthed at different sites in China were analyzed by means of nuclear microscopy. Concentrations and distributions of elements such as Na, Mg, Al, P, S, Ca, Cr, Mn, Fe, Cu, Zn, As, Br, Sr, Y, Ce, Pb and U, etc. were obtained for each sample. The results of quantitative PIXE and RBS analyses show unusually high concentrations of U and Ce in several samples obtained from a period near the K-T boundary (between Cretaceous and Tertiary periods, 65 million years ago), suggesting that some form of environmental pollution could be the cause of dinosaur extinction.     

专家系统在化工中的应用进展

本文综述了近年来专家系统在化工领域的应用状况，并指出今后的发展趋势。     

石膏制品防水防潮剂的研制与开发

本文提出采用高分子有机材料配合，生产石膏制品防水防潮剂的生产方法和工艺。该剂还可以应用到氧化镁系列板材，同时提出开发珠光或彩色防水防潮剂，能达到满足的装饰效果，值提开发推广。     

����ѡ����ˮ��������ܴ���ѧģʽ���о���Ӧ�á�����̸TI��59����������ѧģʽŵģͼ

��Consulting the relevant documents at home and abroad,the author finisheid the derivation of quations about critical flow quantity,critical flow rate,contrast flow quantity,contrast flow rate which are necessary to the continuous water withdrawal through the flow string with different diameters and the rational flow string formula that should be selected when the contrust parameter1.The author also works out the solving programme for TI-59 computer and designs and draws up the nomograrn of mathematical mode.The evident economical results have been obtained from practice of optimizing the flow string for water withdrawal in gas production in Southern Sichuan and from studying the gas-water two-phase flow characteristics through vertical pipe.     

北京核电站模拟器硬件的功能和特点

本文介绍北京核电站模拟器硬件构成并分析其功能和特点。