参数不确定条件下基于 I&I 的异步电机鲁棒控制新方法

针对不确定参数存在条件下异步电机( IM )难以精确进行动态控制的问题,提出了一种基于浸入与不变性( I&I )理论的鲁棒控制方法。在故障工况(转子绕组渐增及负载突变)导致异步电机电气参数存在不确定性的情况下,基于 IM 系统动力学和 I&I 基本原理,通过设计补偿器实现了电机的鲁棒控制,并基于 Lyapunov 直接稳定性方法证明了所设计控制器的渐近稳定性。最后,通过仿真和实验对所提控制方法的有效性和适用性进行了验证。结果表明,所提出的控制方法在参数不确定条件下鲁棒性良好,且在参考信号类型改变时, IM 输出信号仍能够准确、快速地跟踪参考信号。     

DRYING OF ONION: EFFECTS OF PRETREATMENT ON MOISTURE TRANSPORT

ABSTRACT

This study investigated the drying of osmosed and fresh onions. Onion slices (0.8 × 0.8 × 0.15 cm) soaked in sodium chloride solutions (10 and 15% w/w) for 60 min at 22°C were submitted to air drying. The experimental kinetics data obtained were employed to determine effective diffusivity, using a mass transfer model based on Fick's law of diffusion applied to thin slabs. The results show those samples soaked in the 10% NaCl solution had faster drying rates and larger moisture diffusion coefficients. The drying time of onions can be reduced to less than half by introducing an hour of osmotic dehydration in a salt solution. The dried previously osmosed samples presented a more natural coloration than the untreated ones did.     

A zinc dipping technique for Mg–16Li–5Al–0.5RE alloy at room temperature

In order to obtain a high quality protective plating coating on Mg–16Li–5Al–0.5RE alloy, a zinc dipping technique at room temperature was investigated. The zinc dipping technique included two immersion processes, the primary immersion process and the secondary immersion process. Primary zinc transition layers (PZTLs) and secondary zinc transition layers (SZTLs) were obtained after the primary and secondary immersion processes, respectively. The polarization curves, electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM) and X‐ray diffraction (XRD) were employed to characterize PZTLs and SZTLs. The results indicated that immersion time had obvious effects on PZTLs and SZTLs, the optimum primary immersion time and secondary immersion time were 5 min and 30 s, respectively. Then nickel‐plating coating deposited on the SZTL of Mg–16Li–5Al–0.5RE alloy was investigated via EDS, SEM, polarization curves, and EIS. The results demonstrated that the nickel‐plating coating obviously improved corrosion resistance of Mg–16Li–5Al–0.5RE alloy and had good adherence property with the alloy because of the presence of zinc transition layer on the alloy.     

化学沉镍金速率分析与应用

通过试验分析,得出了温度、pH、浓度与化学镍、化学金析出速率的关系,为精确控制化学镍、化学金的镀层厚度、降低化金成本提供了依据。     

湿法纤维板热压机滑轮式自动挡水防渍装置设计浅探

本文提供了滑轮式自动挡水防渍装置设计计算的理论依据；找出了决定该装置设计成功与否的关键参数，并阐明了该参数值大小的决定原则     

印制板化学镍金工艺研究

本文通过正交实验设计,对化学镍金的工艺参数进行研究,提出了化学镍金的工艺设计方案,为建线生产做好了准备工作。     

A novel organ bath design enables the use of saline-immersible lenses on inverted microscopes

We describe the design of an organ bath that is of great advantage for microscopy of living specimens, during physiological experiments, or when used in conjunction with confocal microscopy where deep optical sectioning of living specimens is a priority. For the first time water-immersion lenses of the type that may be immersed directly into physiological saline may be used with inverted microscopes. The novel design of the organ bath allows the lens to have direct access to the specimen through a hole in the base of the bath, without requiring a cover-glass. This method is ideal for experiments in which micropipettes or micromanipulators are in use. The benefit of using saline-immersible lenses for optically sectioning deep into living specimens is discussed, with comparison to results with the more commonly used dry, long-working-distance lenses.     

官厅水库的浸没评价和范围预测

官厅水库的浸没问题是平原型水库带来的典型的环境地质问题，具有较强的代表性．通过分析官厅水库浸没的原因，对水库浸没评价标准评价的确定方法进行了分析探讨．水库浸没范围的预测方法有相关分析法、水动力学法、水均衡法，但采用实地调查资料确定评价浸没标准是最好的方法．     

Photo-electret studies of pure and doped polystyrene films

The photoelectret properties of pure and acrylic acid (AA) doped polystyrene (PS) films formed by an isothermal immersion technique have been studied. The photoelectrets were formed by simultaneous application of u.v. radiation for a short time period (2–10 min) and d.c. electric field (3–18 V). The depolarization current was obtained by reilluminating the photoelectret with the same radiation. It is found that the photo depolarization current increases with polarizing voltage and is greater for the doped samples than for the undoped samples, prepared under identical conditions. The current increases with the dopant concentration and with duration of polarization. The total charge, found by integrating the depolarization current-time curve of doped photoelectrets, tends to saturation at a certain voltage value. Doped PS gives better photoelectrets.     

全方位离子注入及增强沉积工业机和应用

报道了等离子体源离子注入 (PSII)或等离子体浸没离子注入 (PIII)及增强沉积工业机的实验结果及应用。该机真空室直径 90 0mm ,高 10 5 0mm ,立式放置 ,抽气系统由分子泵及机械泵构成并且实现了PLC控制 ,本底真空小于 4× 10 - 4Pa。等离子体由热阴极放电或三个高效磁过滤式金属等离子体源产生 ,因此可实现全方位离子注入或增强沉积成膜。该机的负高压脉冲最高幅值为 80kV ,最大脉冲电流为 6 0A ,重复频率为 5 0— 5 0 0Hz ,脉冲上升沿小于 2 μs,并且可根据需要产生脉冲串。其等离子体密度约为 10 8— 10 10 ·cm- 3,膜沉积速率为 0 .1— 0 .5nm/s。