Measure-theoretic pressure and topological pressure in mean metrics

In this paper, using spanning sets in mean metrics we construct a new definition of measure-theoretic pressure of ergodic measures over a topological dynamical system. And we establish a pressure version of Katok's entropy formula in the case of mean metrics. Furthermore, we also introduce a new definition of topological pressure by replacing the Bowen metrics with the corresponding mean metrics, and prove that the new topological pressure is equivalent to the classical topological pressure. Then the variational principle for the newly defined topological pressure is obtained.     

交流绕组的槽漏抗计算

分析了常见交流绕组槽漏抗计算方法和公式,指出了其不妥之处,给出了实用于常见交流绕组槽漏抗计算的新方法和公式,即分层计算槽漏抗。分层计算槽漏抗与实际情况吻合,而且直观,意义明确。     

随机化的加拿大云杉蚜虫模型

地球上任何物种都离不开自然环境,而自然环境因素通常是不确定的,也就是受到随机因素的干扰．加拿大蚜虫也不例外,针对加拿大云杉蚜虫问题,讨论了一个具有HollingIII功能反应函数随机化的加拿大云杉蚜虫问题模型,利用Lyapunov函数方法证明模型的正解存在的唯一性,并且正解不会在有限时间内爆破．     

基于遗传算法的3-SAT问题判定

通过对遗传算法的改进,引入了聚类排序选择算子,将一个3-SAT的判定性问题转换成一个3-SAT的验证性问题,同时加快了算法的收敛程度,最后给出了基本的求解算法,并分析了该算法的复杂性．实验数据表明,该算法的可靠性有较大地提高,性能明显优于其他同类算法．     

改善温暖地区室内热环境的新途径——除湿

长江流域广大地区有夏闷热而冬阴冷的气候特征,过去以夏日通风隔热而冬日保温防寒的传统措施有一定效果,但不很显著,原因是尚未抓着主要矛盾,以此来改善环境未能收到理想功效。本文论证,以降低湿度以改善室内热环境这一新途径。这可能是湿热地区最为有效和最经济和节能的方法。     

深凹露天爆破震动速度衰减规律实验研究

传统的萨夫斯基公式确定深凹露天爆破振动速度衰减规律时具有很大的误差。提出了一个考虑了药量、爆心距、高程效应、自由面等因素的修正公式模型。现场的实验表明;该修正公式比萨夫斯基公式更好的描述深凹露天爆破振动速度衰减规律;通过合理孔网参数优化也可降低爆破振动速度。     

大跨隧道工程横向地表沉降分析

以南京—常州的茅山隧道为例,结合测量的数据,对其地表的沉降进行分析,并对Peck公式进行检验和修正,与工程的实际情况进行对比,从中得到一些有价值的结论可为其他类似工程提供参考。     

工程计算中关于翅片效率的一个问题

形成扩展表面的翅片管是强化换热中普遍采用的重要方法。但工程上关于翅片效率的计算却出现了混乱,特别是在现行的教科书和工程设计手册中。本文对此情况进行分析,指出正确的工程计算式,以免这一混乱现象继续存在。     

Theoretical analysis of transient recovery voltages when clearing a transformer secondary fault

An analytical formula for the transient recovery voltage and its derivative dv/dt across a circuit breaker has been derived for the case of a transformer secondary fault. A comparison of the calculated results with field test and EMTP simulation results has demonstrated it to have satisfactory accuracy. By applying the formula, the effects of various circuit parameters on the transient recovery voltage and its derivative dv/dt are elucidated. The derivative dv/dt, defined conventionally as the ratio of the crest value and the time to the crest, is found to be about two‐thirds of the maximum value of dv/dt given as a function of time. In addition, a formula for the critical circuit parameters at which dv/dt across a vacuum circuit breaker reaches the critical condition, that is, the circuit breaker fails to interrupt a fault current, is derived. © 2000 Scripta Technica, Electr Eng Jpn, 134(3): 44–52, 2001