Lewis酸存在下的自由基共聚合——Ⅰ.GeCl_4与BCl_3存在下的乙酸乙烯酯与丙烯酸交替共聚

乙酸乙烯酯(VAc)与丙烯酸(AA)在GeCl_4及BCl_3存在下通过自由基聚合可得到交替共聚物。对GeCl_4体系,聚合反应速率正比于[引发剂]~(0.5)。当VAc/AA=1:1(mol比)时有最大反应速率。CCl_4对本聚合反应无链转移作用。通过紫外光谱分析可证实VAc及AA均与GeC\(?)生成络合物;ESR分析表明,络合AA自由基较未络合AA有较强的阳离子特性,交替共聚的原因可能与络合AA自由基及活化单体络合物二者有关。     

非理想多元物系精馏塔动态数学模型

本文给出了一种新的精馏塔动态仿真模型,该模型除了气相上升量的计算是利用焓平衡关系导出的线性代数方程组进行外,其余变量均通过微分方程计算.这就可以避免以往的模型由于解非线性代数方程组不收敛而带来整个计算失败的问题.文中将一种计算病态常微分方程的积分方法——小参数法在IBM-PC/XT微机上算出一个有70层塔板、6个组分的脱乙烷塔模型(600多维的微分方程).小参数法的最大优点是无需矩阵求逆且不必计算雅可比矩阵.     

管式圆筒炉辐射室二维流场和温度场的研究

本文利用“涡量”-“流函数”法求解流场,用R-ε双方程模拟湍流,用Monte-Carlo法模拟辐射传热,燃料燃烧采用简单的燃料和氧气不能共存的单步无限快反应模型.其结果与直径为φ2.29m的常压原油加热炉的标定数据比较,烟气温度场的平均误差为8.89%,流场和另文用射流模型计算的结果相似.     

滴状冷凝传热机理的研究 (Ⅰ)传热表面的制备及传热性能实验

采用离子注入技术对紫铜表面进行处理,在几种表面上都获得了稳定的滴状冷凝.对各种表面进行了冷凝传热性能实验,并对实验结果进行了分析讨论.     

基于Map/Reduce集群上的模式空间划分的序列模式挖掘

通过模式空间划分将基于Map/Reduce处理数据集与候选序列模式集的多对多的对应关系的问题转化为处理数据集与以频繁1-序列为基的各子模式空间的多对多的对应关系问题,大大缩小了中间结果键值对集合的规模,避免了由于组合爆炸导致的单一Map节点的瓶颈问题.通过三轮的Map/Reduce任务,实现了模式空间和过滤规则的建立,并在此基础上实现了各子模式空间上独立地进行序列模式的挖掘.通过充分利用整个模式空间的全局特征及各子模式空间的个性特征,设计了优化的非递归挖掘算法,减少了前缀投影库构造次数及对构造的投影库的扫描次数,从而提高了挖掘阶段的效率.     

时域展宽特性对相关检测性能的影响分析

时域展宽是激光回波脉冲的重要特性,也是影响激光雷达相关检测性能的重要因素。建立了考虑时域展宽特性的激光回波脉冲数学模型,以此模型和相关检测原理为基础分析了时域展宽特性对相关检测测距误差、信噪比的影响,从激光发射脉冲的近高斯能量时间分布模型出发,推导了时域展宽系数的计算公式,并对理论分析和计算结果进行了仿真论证。仿真结果表明:回波脉冲时域展宽系数与其衰减系数成反比,与发射脉冲上升时间成正比,随着时域展宽系数的增大,激光雷达相关检测系统测距误差增大,信噪比降低。     

基才Smoke仿真分析在器件降额设计中的应用

器件降额设计是电路可靠性设计中的一种常用方法。通过降额设计可以达到降低器件基本失效率、提高产品使用可靠性的目的。传统的降额设计存在计算量大、耗时长、是一种静态分析方法、无法估计器件瞬态应力的缺点,基于Smoke仿真分析的降额设计可以准确分析电路中各个器件的瞬态电应力和器件结温。并直接输出所有器件的应力分析和降额情况,从而大大提高了降额设计的准确性和效率。本文采用OrCAD公司PSpice软件中的Smoke高级分析模块,对飞机刹车控制电路的V/I转换模块进行了降额设计仿真,验证了该方案的可行性,从而为电路的降额设计提供了一种新的手段,说明在Smoke分析基础上进行降额设计的研究具有重要的实用意义。     

A signal-decomposed and interference-annihilated approach to hyperspectral target detection

A hyperspectral imaging sensor can reveal and uncover targets with very narrow diagnostic wavelengths. However, it comes at a price that it can also extract many unknown signal sources such as background and natural signatures as well as unwanted man-made objects, which cannot be identified visually or a priori. These unknown signal sources can be referred to as interferers, which generally play a more dominant role than noise in hyperspectral image analysis. Separating such interferers from signals and annihilating them subsequently prior to detection may be a more realistic approach. In many applications, the signals of interest can be further divided into desired signals for which we want to extract and undesired signals for which we want to eliminate to enhance signal detectability. This paper presents a signal-decomposed and interference-annihilated (SDIA) approach in applications of hyperspectral target detection. It treats interferers and undesired signals as separate signal sources that can be eliminated prior to target detection. In doing so, a signal-decomposed interference/noise (SDIN) model is suggested in this paper. With the proposed SDIN model, the orthogonal subspace projection-based model and the signal/background/noise model can be included as its special cases. As shown in the experiments, the SDIN model-based SDIA approach generally can improve the performance of the commonly used generalized-likelihood ratio test and constrained energy minimization approach on target detection and classification.     

A 2.4-GHz dual-mode 0.18-/spl mu/m CMOS transceiver for Bluetooth and 802.11b

High-level integration of the Bluetooth and 802.11b WLAN radio systems in the 2.4-GHz ISM band is demonstrated in scaled CMOS. A dual-mode RF transceiver IC implements all transmit and receive functions including the low-noise amplifier (LNA), 0-dBm power amplifier, up/down mixers, synthesizers, channel filtering, and limiting/automatic gain control for both standards in a single chip without doubling the required silicon area to reduce the combined system cost. This is achieved by sharing the frequency up/down conversion circuits in the RF section and performing the required baseband channel filtering and gain functions with just one set of reconfigurable channel filter and amplifier for both modes. A chip implemented in 0.18-/spl mu/m CMOS occupies 4/spl times/4 mm/sup 2/ including pad and consumes 60 and 40 mA for RX and TX modes, respectively. The dual-mode receiver exhibits -80-dBm sensitivity at 0.1% BER in Bluetooth mode and at 12-dB SNR in WLAN mode.