Based on the discriminating principle of mixed process of sedimentary rocks, dis creminating method of element Cr and Th is applied to the discrimination of sand stone-claystone series of northern Sichuan.

The paper analyses a judging principle of phasechange and phase-out in theory, and a practical usage of the circuit in excavator, also gives a extended application of the circuit. The circuit is simple and useful.

This paper aimes at the character of higher vocational students and focuses on analyzing the distinction principle, based on the presentation of initial-and-ending distinction, through such an angle as 120° from which each stator winding is apart in the space.

Forest natural capital management theory serves on the mode of forest classified management, and it guides to the practice of forest classified management by providing critical natural capital's judgement principles which are 'importance' including to ecological, economical and social aspects and the degree of 'threat'.

Utilized variety rule of superimposed component of compensation voltage and busbar voltage when forward and backward fault occurred, this dissertation put forward the fault directional discriminating criteria based on superimposed component of compensation voltage.

VisibiJty of facesis classified roughly by means of the direction of their normal vector. Then the concept of effective hidden interrelated faces is employed to fur-ther classify the visibility of the concave part of the polyhedron. Meanwhile the maximal and minimal principle is used to distinguish edges and faces where the calculation of intersection are not necessary. Usually the comparison of their depth is not required for distinguishing the visibility of points. The algorithm presented in this article might...

VisibiJty of facesis classified roughly by means of the direction of their normal vector. Then the concept of effective hidden interrelated faces is employed to fur-ther classify the visibility of the concave part of the polyhedron. Meanwhile the maximal and minimal principle is used to distinguish edges and faces where the calculation of intersection are not necessary. Usually the comparison of their depth is not required for distinguishing the visibility of points. The algorithm presented in this article might greatly reduce calculations and get better computing rate than other algorithms. By using hierarchal processing structure and covering techhique the algoithm may have the advantage of saving memory capacity. Therefore, it could be executed on a 48K Apple-Ⅱ microcomputer.

There arc two stability control devices used in a power network in North China:one based on the change of network power and another based on the change of power angle.The first part of this paper describes the criterion of transient stability for each device,their computation methods and their constitution block diagrams.The second part gives the perfor- mance of fast-valving of a steam turbine,which is used as the principal measure for power system stability,and presents the results of a field test for fast-valving...

There arc two stability control devices used in a power network in North China:one based on the change of network power and another based on the change of power angle.The first part of this paper describes the criterion of transient stability for each device,their computation methods and their constitution block diagrams.The second part gives the perfor- mance of fast-valving of a steam turbine,which is used as the principal measure for power system stability,and presents the results of a field test for fast-valving on a 200 MW turbogenerator set.

本文概述了华北某电网使用的稳定控制装置的概况和功能。文中叙述了基于功率变化和功角变化的两种暂态稳定极限判别的原理、计算方法和构成框图,两种原理的装置同时应用,互为补充。文中还叙述作为主要稳定措施的汽轮机快控汽门的特性,以及在 S 发电厂20万千瓦机组进行快控汽门现场试验的情况。

A case-control study was carried out among 104 pairs of mothers of preterm and term infants at Jianli County of Hubei Province and some other places alike. Single factor analysis and Conditional Logistic Model were used to analyze the data. The results showed that twins (complete separation type), vaginal spotting or bleeding during pregnancy (RR 3.77), preterm delivery history (3.91), life events during pregnancy (3.20), infertility history (3.00) and fatigue index (1.40) were the risk factors related with...

A case-control study was carried out among 104 pairs of mothers of preterm and term infants at Jianli County of Hubei Province and some other places alike. Single factor analysis and Conditional Logistic Model were used to analyze the data. The results showed that twins (complete separation type), vaginal spotting or bleeding during pregnancy (RR 3.77), preterm delivery history (3.91), life events during pregnancy (3.20), infertility history (3.00) and fatigue index (1.40) were the risk factors related with preterm labor. Another study was also undertaken in Wuhan, Hubei. The investigated population consisted of 245 mothers, including 140 mothers with preterm delivery. The results were almost as the same as those of the first study. By using the six risk factors above as discriminatory indices, a discrimination table was developed to discirminate preterm .from term delivery of the two batches of data. The efficiency of discirmination was highly significant.