Investigation of redox initiators for free radical frontal polymerization

BACKGROUND: The reaction temperature for frontal polymerization (FP) initiated by redox initiators can be greatly decreased compared with FP initiated by peroxide initiator and disulfide initiator. We report the synthesis of poly(hydroxyethyl acrylate)s via free radical FP using benzoyl peroxide (BPO)/N,N‐dimethylaniline (DMA) and ammonium persulfate (APS)/N,N,N′,N′‐tetramethylethylenediamine (TMEDA) couples as redox initiators at ambient pressure. RESULTS: The results show that unlike the phenomenon of bubbles and ‘fingers’ when using BPO alone, a self‐sustaining and stable front can be obtained when the [DMA]/[BPO] ratio is higher than 1 (mol/mol). A slight increase of the DMA (or TMEDA) reductant concentration causes a marked decrease of front temperature to 53 °C (or 61 °C). CONCLUSION: We investigated the effects of the ratio of the oxidant to the reductant and the initiator and monomer concentrations on certain parameters of FP: formation of bubbles, front velocity and front temperature. This opens the way to the potential development of FP using more appropriate monomers with low boiling points. Copyright © 2009 Society of Chemical Industry     

保护层一次开挖爆破技术在龙华口枢纽工程的应用

水电工程基岩保护层开挖按常规施工方法,需进行分层开挖,并根据岩石情况,留有一定的撬挖层。这种开挖方式很难适应大、中型水电工程任务重,工期紧的特点,极大地影响着工程进度。随着新型爆破材料的发展,爆破技术的不断提高,保护层开挖方式有了改进和突破。借鉴其他工程经验,在龙华口枢纽工程坝基保护层开挖施工中,根据其地质条件,采用一次性爆破开挖技术并获得成功,文中叙述了龙华口工程施工经验。     

Influence of chemical polishing on fluorophosphate fiber preform

Surface treatment of optical glass fibers is an effective method to clean the impurities and remove the damage layer, such as scratches caused by the cold processing. Optical losses at the fiber core/cladding interface can thereby be decreased. Using X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM), we studied the surface composition and morphology of fluorophosphate (FP) glass after polishing and chemical etching. In addition, we investigated the etching mechanism and the optimal concentration of etching solution. Results show that the surface composition is very close to that of the bulk glass for some elements, and the root-mean-square (RMS) roughness is approximately 0.821 nm. A method including acid–alkali pretreatment and a second polishing step is a novel way to improve the smoothness of surface and to eliminate defects such as contaminants and scratches.     

神经网络学习中“附加样本”的技术

本文将网络的先验知识和网络的样本集知识有机结合起来,提出“附加样本”的神经网络新学习算法,其计算复杂性仅为多项式(上界≤O(n⁴)),用该算法可以设计出性能更好的神经网络.本文第1节简单介绍FP算法以及FP覆盖算法,第2节提出FP统计附加样本算法.最后举一例子说明用该算法可以设计出性能良好的网络.     

基于FP算法的神经网络综合方法

本文应用ＦＰ算法，给出神经网络两个常用的综合方法：合并法与递归法，并通过具体实例，介绍这些综合方法的基本思想。     

Robust observers for neutral jumping systems with uncertain information

In this paper, the problem of designing observer for a class of uncertain neutral systems. The uncertainties are parametric and norm-bounded. Both robust observation and robust H_∞ observation methods are developed by using linear state-delayed observers. In case of robust observation, sufficient conditions are established for asymptotic stability of the system, which is independent of time delay. The results are then extended to robust H_∞ observation which renders the augmented system asymptotically stable independent of delay with a guaranteed performance measure. Furthermore, a memoryless state-estimate feedback is designed to stabilize the closed-loop neutral system. In all cases, the gain matrices are determined by linear matrix inequality approach. Two numerical examples are presented to illustrate the validity of the theoretical results.     

基于PTR2000模块的家庭智能电子开关

研究设计了一种基于无线收发数传模块FTR2000的家庭智能电子开关，实现了家庭照明电灯、电器设备等集中控制的电子化、遥控化，文中阐述了其硬件设计、软件设计和采用的抗干扰措施。     

Parallel Fuzzy P＋Fuzzy I＋Fuzzy D Controller： Design and Performance Evaluation

In this paper, a parallel fuzzy proportional plus fuzzy integral plus fuzzy derivative (FP+FI+FD) controller is proposed. It is derived from the conventional parallel proportional-integral-derivative (PID) controller. It preserves the linear structure of a conventional parallel PID controller, with analytical formulas. The final shape of the controller is a discrete-time fuzzy version of a conventional parallel PID controller. Computer simulations are performed to evaluate the performance of the FP+FI+FD controller for setpoint tracking and load-disturbance rejection for some complex processes, such as first- and second-order processes with delay, inverse response process with and without delay and higher order processes. Also, the performance of the proposed fuzzy controller is evaluated experimentally on highly nonlinear liquid-flow process with a hysteresis characteristic due to a pneumatic control valve. The simulation and real time control is done using National Instrument hardware and software (LabVIEW). The response of the FP+FI+FD controller is compared with the conventional parallel PID controller, tuned with the Ziegler-Nichols (Z-H) and Astrom-Hagglund (A-H) tuning technique. It is observed that the FP+FI+FD controller performed much better than the conventional PI/PID controller. Simulation and experimental results demonstrate the effectiveness of the proposed parallel FP+FI+FD controller.     

“组态王6．5”与FP0-C32CT在仪器柜控制系统中的应用

文章介绍了仪器柜控制系统的应用需求,设计了一套由“组态王6.5”作为上位机,PLC、转换面板和电子锁为下位机的仪器柜控制系统,并叙述了系统的主要功能、组成、工作流程、系统编程及组态过程。实际使用表明,“组态王6.5”与FP0-C32CT在此柜控系统中的应用使得该系统图形界面友好、操作简单,运行稳定。     

IGBT平面高压终端结构的研究

耐压是 IGBT的一个重要参数 ,所以其高压终端结构的研究一直受到人们的重视。针对常规采用的场限制保护环法和场板法高压终端结构的缺陷 ,本文提出了场板混合终端结构。此结构结合了场限制环和场板的各自优点 ,可使得击穿电压对环间距、氧化层厚度及氧化层电荷的敏感程度大大降低 ,从而简化了工艺的复杂性 ,并可获得最佳的耐压效果。本文首先对场板混合终端结构的优化设计进行了解析研究 ,提出了一套完整的设计理论 ,然后通过实验验证了此理论的正确性