NONNULL DISTRIBUTION OF THE LIKELIHOOD RATIO CRITERION FOR TESTING THE EQUALITY OF DIAGONAL BLOCKS WITH BLOCKWISE INDEPENDENCE

In this paper, the nonnull moments and the distributions of the likelihood ratio criterion for testing the equality of diagonal blocks with blockwise independence under certain alternatives have derived.

Effects of T6 heat treatment on mechanical, abrasive and erosive-corrosive wear properties of eutectic Al-Si alloy

The abrasive and erosive-corrosive properties of eutectic Al-Si （LM6） alloy were studied. Microstructural features of the alloy were altered by controlling the T6 heat treatment parameter, and their influence on hardness, strength and elongation, and response of the samples in erosion-corrosion and abrasion conditions were studied. Characteristics of the Al-Si alloy samples were compared with those of Al conventionally used in agricultural machineries. Fabrication of a typical component using the Al-Si alloy was also explored in order to understand the feasibility of using the alloy system for the envisaged applications. The study suggests the response of the samples in different conditions to be greatly influenced by parameters like chemical composition, microstructural features and applied load, traversal distance and test environment. The performance of even the as cast Al-Si alloy is far superior to that of the conventional Al samples, while the T6 heat treated Al-Si alloy shows improved performance. Accordingly, the as-cast as well as T6 heat treated Al-Si alloy has potential for applications in agriculture as a replacement for the conventionally used Al.

Cardiovascular Effects of an Organophosphate Toxin Isolated from Ptychodiscus brevis

:The dose-dependent hypotensive and bradycardic effects induced by an ichthyotoxic organophosphate compound isolated from the marine dinoflagellate Ptycholiscus brevis were studied. These effects were not antagonized by atropine, but potentiated by α-adrenoceptor blocker and hexamethonium. The toxin aboished the vasopressor effect elicited by phenyle phrine, indicating an α-adrenergic blocking activity. The cardiovascular depressor responses were antagonized by tetraethylammonium while blockade of cholinergic and histaminergic re ceptors or inhibition of prostaglandin synthesis failed to modify these effects. The results indi cate that the cardiovascular depressor effects of the toxin are probably mediated through α-a drenergic and ganglionic blockade accompanied by modulation of potassium channel activity

安装在NTPC公司项目中超高效IE3电机的案例分析

随着能源的不断消耗及人们环保意识的增强，可持续发展逐渐成为人们关注的焦点。目前，常采用的节能措施有：安设VFD（变频器）等新技术装置，优化设备尺寸，引入超高效电机。这些方法既可以单独，也可以联合使用。本文主要对效率提升3％到20％的电机进行研究，论述其对于印度这样的发展中国家在节能方面的巨大潜力。若以一超高效IE3电机代替普通电机，则对于典型的100kW电机来说，所花费的额外成本将在一年之内被收回。即使更换现有安装中LT电机的全部要求，其总成本也将在三年之内被收回。本文研究了一些需要关注的问题，探讨了现有电站是否需要更换。在决定是否更换为超高效电机时，需要考虑的最主要问题不是成本花费，而是设备的质量及平稳无故障运行，那是用户的一个梦想。超高效电机固有的设计特点不仅可以提高设备的稳定性，并且可以缩短停机时间及降低维护成本。由于C02排放量的大幅削减，环保问题也在日益得到改善。因此许多国家更换超高效电机的计划势在必行。该文旨在评价更换超高效IE3电机后的设计改进、性能指标、经济花费三方面的效用价值。早前采用的测试方法假设杂散损耗为0．5％，而如今的测试方法可以通过测量转矩和速度两个机械参数而得到精确杂散损耗值。LT电机杂散损失的精确值通常为1．5％-2．5％，这要比之前假设的0．5％高出很多。因此，超高效电机不仅可以根据IEC列表给出效率增加的精确值，并且充分考虑到目前所普遍使用的效率测量方法的缺点。一标称效率为80％的电机，实际上是以78％的效率输出机械能，由于IE3电机标称的效率是基于实际损耗测量的，因此可以克服标称与输出不一致这一缺点。该文主要阐述了电机绕组所受应力及影响电机寿命的因素。为确保电机的使用寿命及高质量运行，该文考虑了如下问题：（1）电机内部应力的产生原因；（2）超高效电机中如何通过设计手段来降低应力。