高动态接收机的关键问题研究

为检测高动态GPS(Global Positioning System)信号,需要设计码环及载波环的捕获与跟踪数字系统.在高动态下,在GPS信号的码跟踪和载波捕获与跟踪问题中最关键的是要解决在高加速度下的载波跟踪问题.主要讨论了在高动态下,结合GEC公司的十二通道相关器GP2021,载波跟踪环路的特性并在此基础上提出了一个新的方法来改善载波跟踪环路的性能.     

神光Ⅲ原型装置主放大器剩余热畸变模拟研究

给出了神光Ⅲ原型装置主放大器系统的热畸变模型 ,该模型包括三个模块 :热传输模块、热弹性力学模块、光学模块。利用该模型对原型装置的剩余热波前畸变进行了研究。初步结果表明 ,通过优化的冷却方案 ,可以在装置预定的运行周期内将激光工作介质内的温度梯度和总体平均温度冷却到可以接受的水平 ,剩余热波前畸变满足设计要求。利用该模型还定量地研究了增益介质的热膨胀系数与剩余热畸变之间的关系     

Stress relaxation behavior of composite and eutectic Sn-Ag solder joints

Stress relaxation experiments were carried out at 25 C and 150 C on 96.5Sn-3.5Ag eutectic solder and Sn-Ag composite solder joints (Sn-Ag eutectic solder with 20 vol.% Cu₆Sn₅ reinforcements incorporated by in-situ methods). The magnitude of the stress drop during relaxation depends primarily upon the plastic shear strain imposed prior to the stress relaxation process. For sequential stress relaxation experiments that include unloading, the stress drop is nearly independent of the accumulated plastic shear strain. However, for sequential stress relaxation that does not include unloading, the stress relaxation is more dependent upon the cumulative plastic shear strain history. The stress in single shear lap joints does not relax to zero stress, as is observed in stress relaxation of bulk tension specimens, even at 150 C. Creep strain rates extracted from the relaxation data were much lower with smaller pre-strains in both eutectic Sn-Ag and composite solder joints. The stress exponent values (n) calculated from the stress relaxation test data ranged from 7 to 15 for both eutectic and composite solder joints, which were consistent with conventional creep data. These stress-relaxation behaviors can be explained on the basis of dislocation recovery processes that occur during relaxation and when specimens are unloaded.     

Hydrogen plasma passivation of bulk GaAs and Al0.3Ga0.7As/GaAs multiple-quantum-well structures on Si substrates

Hydrogen (H) plasma passivation effects on GaAs grown on Si substrates (GaAs on Si) are investigated in detail. H plasma exposure effectively passivates both the shallow and deep defects in GaAs on Si, which improves both the electrical and optical properties. It was found that the minority carrier lifetime is increased and the deep level concentration is decreased by the H plasma exposure. In addition, after H plasma exposure, room temperature photoluminescence (PL) for Al_0.3Ga_0.7As/GaAs multiple-quantum-well (MQW) on Si is enhanced with a decrease in the spectral width.     

少子产生寿命计算机辅助测量及应用的研究

研究了半导体材料少子产生寿命的计算机辅助测量 ,设计了相应的产生寿命 C- t瞬态测量系统 ,能实现从阶跃信号产生直到测量结果输出全过程的自动化 ,提高了测量速度和准确度。应用于传统的“Zerbst图”法 ,可在原理和数据处理两方面得到较大的改善。     

动态应力下MOS器件热载流子效应研究

研究了 MOS器件中的热载流子效应 ,在分析了静态应力下 MOSFET寿命模型的基础上 ,提出了动态应力条件下 MOSFET的寿命模型。此外 ,还研究了沟道热载流子的产生和注入与器件偏置条件的关系 ,讨论了热载流子效应对电路性能的影响。通过对这些失效因素的研究和通过一定的再设计手段 ,可以减少热载流子效应导致的器件退化     

Azothia- and Azoxythiacrown Ethers as Ion Carriers. Part I. Cationic Response of Membrane Electrodes

13-Membered azothia- and azoxythiacrown ethers have been applied as ion carriers in ion-selective membrane electrodes. Their sensitivity and selectivity were studied towards alkali, alkaline earth, transition and heavy metal cations. It was found that membranes doped with the azoxythiacrown ether (A) show higher affinity towards Pb²⁺ than Cu²⁺ (log K_Cu,Pb ^pot = 1.7), whereas membranes with the azothiacrown ether (B) are more selective towards Cu²⁺ than Pb²⁺ (log K_Cu,Pb ^pot = -2.4). The discrimination of alkali and alkaline earth cations was found to be greater for B than for A. Electrodes with both ionophores suffered from strong interference by Ag⁺ and Hg²⁺. The relation between the carrier structure and electrode properties has been discussed.     

中国硫回收技术进展(英文)

综述了国内硫回收技术的现状,并对今后１０－１５年内硫回收技术的发展进行了展望。     

作物秸秆降解中稀有机酸的萃取回收

作物秸秆有机降解的研究中,有机酸的回收利用是一个非常重要的环节,本研究采用低沸点的乙酸乙酯和高沸点的磷酸三丁酯（TBP）作萃取剂,对作物秸秆有机酸（乙酸,丙酸）降解中不同浓度的稀有机酸溶液（汽提液和洗涤液）用液－液淬取法回收,结果表明：磷酸三丁酯的萃取能力大于乙酸乙酯,同一萃取剂对丙酸的萃取效果比对乙酸好。     

聚丙烯酸载体用于青霉素酰化酶的固定

以反应性单体丙烯酸和交联剂二乙烯基苯,以石油醚为致孔剂,通过悬浮聚合制备固定化酶的载体,并用于对青霉素酰化酶的固定。研究了丙烯酸与二乙烯基苯以不同摩尔比对青霉素酰化酶固定活性的影响,以及悬浮聚合时水油相比例的不同所合成的载体对固定化酶性能的影响。当丙烯酸和二乙烯基苯摩尔比为84.2:4时合成的载体固定青霉素酰化酶的酶活为2784U/g,而水油相比为2.75:1（丙烯酸和二乙烯基苯摩洋比为84.2:5）时固定青霉素酰化酶活达到2183U/g。固定青霉素酰化酶可使青霉素转化,得到半合成青霉素的中间体6-氨基青霉烷酸,由此可制成高效、广谱、服用方便的新青霉素。