POLYOPTIMIZATION PROBLEM IN POWER CORE–TYPE TRANSFORMER DESIGN

ABSTRACT

The paper describes an optimum mass–efficiency design of power single–phase core–type air–blast oil Immersed transformer. The optimization problem is reduced to finding the minimum of the modifying scales function In a 6–dlmenslonal space bounded by 18 or 19 operation and design Inequality constraints based on Kuhlmann theory. To increase the efficiency of transformer modeling, it is used the first author's Idea of two–level hierarchic optimization modeling system. As an application example, an American existing transformer has been optimized. The polyoptimization problem has been solved for discrete net of scales factors. Based on a principle of maximum benefit, the polyoptimum–preferred design has been selected afterwards.     

Investigation of the effects of mechanical post‐processing with a colloid mill on the texture properties of stirred yogurt

Texture properties of stirred low‐fat yogurt were investigated in terms of processing after fermentation. The yogurt gel was pumped through a colloid mill at two gap widths and various peripheral velocities of the rotor. The storage modulus and yield stress were measured after 1 day and after 3 weeks, and the occurrence of syneresis was noted. The main factor for the structural degradation in the shear gap was the mean peripheral velocity of the rotor, rather than the apparent shear rate. Syneresis is related to a certain level of the storage modulus. The yield stress correlated with the storage modulus.     

小钻头大作用

瑞士Aeschlimann共有160名员工,主要加工直径1～70mm的电子元件和汽车零件,同时也加工拖车、钟表及液压与仪器仪表零件.该公司成立于1937年,从生产钟表螺钉起家.随后几年,凭借其高质量产品,该公司迅速扩张,从机械化开始,逐步发展成超小型螺钉系列化自动化生产企业.现在已成为一家国际化加工企业.     

Thermostatic tissue platform for intravital microscopy: 'the hanging drop' model

Intravital microscopy imposes the particular problem of the combined control of the body temperature of the animal and the local temperature of the observed organ or tissues. We constructed and tested, in the rat ileum microcirculation preparation, a new organ‐support platform. The platform consisted of an organ bath filled with physiological solution, and contained a suction tube, a superfusion tube, an intestine‐support hand that was attached to a micromanipulator and a thermometer probe. To cover the intestine we used a cover glass plate with a plastic ring glued on its upper surface. After a routine procedure (anaesthesia, monitoring and surgery), the intestine segment (2–3 cm long) was gently exteriorized and placed on the ‘hand’ of the organ support. A small part of the intestine formed a small ‘island’ in the bath that was filled with physiological salt solution. The cover glass was secured in place. The physiological salt solution from the superfusion tube, which was pointed to the lower surface of the cover glass, formed a ‘hanging drop’. The objective of the microscope was then immersed into distilled water that was formed by the cover glass plastic ring. The ‘hanging drop’ technique prevented any tissue quenching, ensured undisturbed microcirculation, provided for stable temperature and humidity, and permitted a clear visual field.     

Triggering of Cathode or Emitter Coupled Univibrators Connected into a Chain†

The possibility of direct triggering of one cathode or emitter coupled univibrator by the differentiated cathode or emitter voltage jump of the other is discussed and analysed, for univibrators connected into a chain. Simple approximate relations are derived for the univibrator optimum trigger pulse nominal threshold voltage and for the maximum permissible deviation from their nominal parameters, which show that this way of triggering is suitable both for transistor and for tube circuits.     

基于微机电系统的纳米力学测量装置的研制

阐述了一种基于微机电系统的纳米力学测量方法和系统。开发了一种多功能的纳牛力致动器,可同时满足微拉伸测试系统、原子力显微镜等系统的需要,该致动器基于微机电系统,以静电侧向梳齿为基本结构,采用变间隙设计结构,实现小芯片尺寸、低压驱动、高分辨率(nN量级)和大输出力（大于1 mN）,并介绍了该测试系统的原理、结构、微机电系统的安装以及一些相关实验结果。     

Monostable Circuit Triggered with Pulse Trains†

The behaviour of a monostable trigger circuit, which is triggered with periodic pulse, trains is analysed by determining the sequence of its division ratio. Some general properties of these sequences are found, from which it follows that the sequence may show irregular changes, periodical changes or take a constant value of the division ratio after a sufficient number of cycles. Some conditions are found which must be satisfied for the sequence to have one of the above-mentioned properties. Periodical changes are obtained only in exceptional cases.