Flashover voltage characteristics of contaminated station insulators under temporary ac overvoltages in the ac system connected with a frequency converter station

According to the recent analysis results of temporary ac overvoltage in the ac system connected with a frequency converter station, large-magnitude over-voltages were confirmed to occur under some special system conditions. Most of the station insulators currently used cannot withstand such overvoltages according to an evaluation based on the data obtained earlier. The necessity of tests to be done to evaluate such performance more accurately was recognized. Both power frequency and switching impulse overvoltage flashover tests were made on contaminated insulators by the method well simulating the natural wetting condition. Switching impulse flashover voltage with the waveshape having a long wavefront time of 2 ms can be well correlated with the flashover voltage characteristics of temporary ac overvoltage. Higher flashover voltage characteristics were obtained by a clean fog test method compared with those obtained by equivalent fog test method.     

阶梯轴的横向弯曲振动

利用广义函数导出阶梯轴横向弯曲振动的微分方程。应用作者在文献[1]、[2]中引入的 W 运算符,给出了建立阶梯轴横向弯曲自由振动的特征方程的一般简易方法。文中还讨论了应用广义函数的 Fourier 展开来求解阶梯轴横向弯曲强迫振动响应的方法。     

Energy Value of Resistant Starch

Resistant starch was evaluated for energy value using fine silica and normal starch as controls and young rats as a test model. The net increase in rats' carcass energy due to the test materials fed over a 3-wk period formed the basis for assessing energy value. Rats fed normal starch deposited about twice as much fat and significantly more protein in the carcass than those fed either resistant starch or silica. Rats fed resistant starch or silica showed similar growth responses and increases in components of body composition and carcass energy content. This suggested that resistant starch provided, like silica, no energy.     

On the hollowness ratio effect on the dynamics of a spinning Rayleigh beam

The analytical solutions of a spinning Rayleigh beam with rotatory moment inertia and gyroscopic effect are presented in this paper. The critical speeds can be written analytically in a function of the length-to-radius ratio (l) defined by the beam's length over its outer radius and the hollowness ratio (α) defined by the hollow area over the total area of the cross section. The sensitivity analyses show that the critical speed is decreasing with l, but increasing with α. Moreover, α is more sensitive to the critical speeds. The design of a spinning beam should therefore be emphasized more on the hollowness factor. Contrary to common belief, only finite critical speeds exist and the number is independent of the boundary conditions. It increases monotonically with l, but decreases with α. The steady state unbalanced response can therefore be expressed analytically by the finite precessional modes and the corresponding generalized coordinates.     

A review of robust design methods for multiple responses

Problems in engineering design often involve determining design variable settings to optimize individual product performance for multiple criteria, which are often in conflict. We review mathematically rigorous techniques from the statistical literature for finding a vector x of design variable settings, which produces an optimal compromise solution among a group of prioritized response variables. The best compromise solution is typically gained by optimizing an objective function, which incorporates the prioritized demands of multiple responses. Since most multi-response objective functions are constructed by combining the functions used to optimize univariate responses, a review of the prominent univariate approaches is presented first. A multivariate approach from the engineering literature called the compromise Decision Support Problem is also reviewed. Finally a table comparing the relative merits of the different multivariate approaches summarizes the article in a concise and user-friendly fashion.     

广义频率响应函数的鲁棒建模新方法

针对基于非线性谱分析的故障诊断技术的需要,研究了非线性系统的广义频率响应函数的鲁棒在线建模方 法。首先将次元分析算法应用于Volterra级数模型的辨识,并通过对此算法的修正,得到了一种改进的Volterra系统的鲁 棒辨识算法。对其鲁棒性能进行的分析表明,改进算法的鲁棒抗噪性能被明显提高。在此基础上,提出了一种广义频率响 应函数的两步鲁棒建模新方法。仿真实验表明,该方法具有良好的鲁棒收敛性能,能够有效解决GFRF的在线建模问题。     

Corroles as receptors in liquid membrane electrodes and their potentiometric response towards salicylic acid

Here, we report on the application of corroles as analytically active compounds in liquid membrane electrodes (ISE) that are sensitive towards salicylic acid and salicylate.The potentiometric signals generated by corrole-incorporated ISEs strongly depend on the pH of the aqueous sample solution and the membrane composition, such as the presence of lipophilic sites. Corrole incorporating ISEs are characterised by a low detection limit (4.0 × 10⁻⁵ M) and a wide linear range (4.0 × 10⁻⁵ to 5.3 × 10⁻³ M). Also, they are free from interference versus other organic anions.The mechanism of the generation of the potentiometric signals of corrole incorporating ISEs in the presence of salicylate anion, as well salicylic acid, will be discussed.     

准噶尔盆地腹部超压层分布研究

准噶尔盆地腹部普遍发育深层（大于4000m）超压系统，很多钻井都钻遇超压。通过对超压段钻井、地质、测井、地震特征系统研究发现，超压段泥浆密度大幅增加，具有高声波时差、低电阻率以及地震低速的超压响应特征。利用Dix公式计算地震层速度和利用Fillippone公式计算地层压力，得到超压数据体。准噶尔盆地腹部超压在白垩系及其以下沉积地层中均有分布，超压层的深度范围不同。分1井西凹陷边缘以及昌吉凹陷西南有空层现象。超压顶面分布的层位由北往南、从东到西逐渐变浅，从三叠系顶部到白垩系底部。深部超压对油气分布和富集有着重要的控制作用，准噶尔盆地腹部超压层分布的研究将对本区油气勘探起积极的推动作用。     

Experimental Study about Activated Water Generated by the Electro—hydraulic Impulse Strengthening the Mechanical Performance of Concrete

On the basis of a great number of experiments, it is proved that the strength of concrete is improved greatly when it is mixed with activated water produced by the electro-hydraulic impulse.With the proper parameters, the compression strength of concrete can be increased by 45% .The reason for improvement of concrete strength by using activated water is discussed from the aspect of the structure of molecule.     

低剂量X射线照射诱导HeLa细胞存活的

采用集落形成法观察了低剂量X射线照射HeLa细胞的存活率，结果表明，小于0．5Gy的X射线照射细胞的存活率高于对照，得到了HeLa细胞存活的“兴奋效应”，而且在0．25Gy附近这种效应更为明显；低剂量D1（0．05，0．75Gy)的预照射降低了随后攻击量D2对细胞的损伤程度，反映出低剂量照射可诱发细胞存活的“适应性反应”。