Steady-state torque control system with secondary-current feedback for three-phase squirrel-cage induction motors

This paper presents a highly stable steady-state torque control system with a feedback of a secondary current signal. The torque control system is constructed with a feedback of the secondary current (I₂) signal using a quick response magnetic-field sensor constructed with an amorphous core multivibrator bridge, which can solve the secondary resistance change problem for temperature variation in the IM. Moreover, we added a state feedback to the system to improve the response speed for the unit step function of a torque order. The I₂ sensor method has advantages especially at a low-speed range, in which conventional method using an integrator shows control errors.     

Conceptual design of a high-efficiency absorption cooling cycle

The search for high-efficiency, gas-fired cooling cycles has led to the development of dual-loop absorption machines with cooling coefficients of performance (COPs) in the 1.2 to 1.7 range. This increased performance may call for high generator temperatures, new working fluids or new materials of construction. In most cases, two different sets of working fluids are required. The conceptual design presented here is aimed at obtaining high efficiencies with relatively low temperatures, employing only one set of fluids. The concept consists of two loops coupled in a configuration aimed at minimizing the loss of thermodynamic availability incurred when transferring refrigerant between the loops. The working fluid pair is a solution of lithium bromide-water. The calculated COPs are of the order of 1.8. The cycle relies on an elaborate evaporator-absorber combination. The paper presents the conceptual design, the critical assumptions, and the performance calculations for the concept.     

步进式加热炉炉温优化设定模型及软件开发

针对线材厂步进式加热炉实际工况，提出了基于经验规则的炉温优化设定模型和在线自学习获取知识的思想，并以炉温优化设定模型为核心，开发出加热炉计算机控制系统的优化运行软件。     

Parallel feedforward class-AB control circuits for low-voltage bipolar rail-to-rail output stages of operational amplifiers

A new family of class-AB control circuits for bipolar rail-to-rail output stages of operational amplifiers is presented. Step by step, we report the development of five simple class-AB control circuits showing the advantages of using parallel feedforward. The circuits have been designed in such a way that temperature, supply voltage and process parameters have little influence. To test the output stages, one of them has been implemented in a very simple two-stage operational amplifier on a semi-custom chip. Measurements show a bandwidth of 2.5 MHz, a gain of 40 dB, a quiescent current of 23µA and a maximum output current of 250µA. Simulation results of three other simple operational amplifiers with the new class-AB control circuits are shown, which have a higher gain and maximum output current.     

初论带状光纤缆结构设计

推导出了成叠带状光纤在松套管中余长的两个计算公式，此两公式是带状光纤缆结构设计需要用到的基本公式。此外，还对带状光纤缆结构设计作了初步讨论。     

Membrane Packaging System to Permit Safe Hydration of Freeze-Dried Contents with Impure Water

We tested the feasibility of using polymer membranes for a self-hydrating packaging system to reconstitute freeze-dried foods using nonpurified water. Several commercial membranes were screened according to (1) hydration rate, (2) water permeability, (3) passage of microorganisms, (4) salt rejection, and (5) strength. The most promising membranes were used for developing and testing prototype packaging systems. A feasible self-contained rehydration system was a nylon-6 polyamide membrane that rehydrated the freeze-dried food within 30 min while passage of microorganisms was prevented. The temperature was 37°C, and the food contained 0.5g/5g of a low molecular weight solute (salt). Such self-contained membrane rehydration systems must be designed to accommodate expected environmental conditions such as temperature, relative humidity, and nature of the product.     

大型储罐的罐壁设计

根据十万立方米浮顶油罐罐壁板应力测试的实测结果，运用应力分析程序，对罐壁板应力分布情况进行了分析和比较，通过调整罐壁板的厚度，使新设计储罐的罐壁板应力分布更加均匀、合理。     

玻璃包装改进及经济效益分析

论述了平板玻璃包装技术改进对提高包装质量和企业经济效益的影响,介绍了平板玻璃包装箱(架)的性能,简述了计算机辅助设计及计算机辅助管理在玻璃包装结构设计及包装质量管理中的效用。     

线阵CCD驱动器模块的优化设计

介绍了应用层次分析方法优化设计线阵ＣＣＤ驱动器模块的设计方案。设计出１６档可变积分时间，五档可变驱动频率，具有行同步和采样同步脉冲输出的通用型驱动器模块。它容易与各种计算机接口，广泛地应用于各种光谱仪器、精密尺寸检测仪器中。