一种用于超导测量的微弱信号放大器

本文介绍了一种用于超导临界温度Ｔｃ测量的双端输入微弱信号放大器，分析了它的设计特点、电路原理及技术措施。     

聚氧乙烯烷基酚醚羧甲基钠盐的提纯及表面活性

用硝酸银作沉淀剂，采用沉淀法提纯了标称氧乙烯（ＥＯ）数分别为２和４的聚氧乙烯烷基酚醚羧甲基钠盐，纯度在９９．８％以上。测定了不同温度和离子强度下的表面张力，由热力学关系计算出其表面性质和胶团化及表面吸附过程的标准热力学函数。结果表明，标称ＥＯ数由２增至４时，分子的最小截面积增加，反离子结合度减小，表面张力降低能力则下降很小。加入氯化钠，可使表面活性分子的最小截面积明显减小，却对表面张力降低能力影响甚微。     

二阶导数光谱法同时测定混合甘油酯中一酯、二酯、三酯的含量

采用二阶导数光谱法，试样不需分离，直接测定混合甘油酯中一酯、二酯、三酯的含量．     

浅谈梁氏变换的完备性：与梁尺峰先生商榷

梁氏变换下的非瞬时尺缩效应公式是不正确的，梁氏变换下，加速系仍然不是单一的体系，梁氏力学公式不可能是精确的公式。梁氏变换允许超光速体系存在，这又导致“信号的最大传递速度为光速”的假定失去意义。     

RING OPENING POLYMERIZATION OF GLYCOLIDE

The influence of reaction temperature,reaction time, system pressure and catalysts on the re-duced viscosity(η_(sp)/C)and shear viscosity(η_a)of polyglycollic acid(PGA)is given in thispaper.The adequate polymerization condition of glycolide is selected according to the conditionalexperiments.The heat of polymerization and the activation energy at different conversion levelsare also measured by DSC.     

The long-term denudation rate of granitic regolith in Qinhuangdao,North China determined from the in situ depth profile of the cosmogenic nuclides 26Al and 10Be

This study quantifies the surface denudation rate of granitic regolith via the application of the in situ cosmogenic ^26Al and ^10Be depth profile in China. The concentration ranges of ^26Al and ^10Be in the quartz along the -3-m granitic regolith profile in Qinhuangdao are （4.9-23.1） × 10^5 and （2.3-36.6）×10^4 atoms/g, respectively. With the exception of the surface sample, both ^26Al and ^10Be concentrations decrease exponentially with sample depth. The Chi-square best-fitting results revealed a total denudation rate of -9 m/Ma averaged over a 103-105 a timescale, which is lower than the values observed in global granitic outcrops. Compared with global datasets, the flat terrain due to the lack of tectonic activities is most likely the dominant factor that controls the local denudation process. The surface sample offsets from the theoretical cosmogenic nuclide distribution implies that the denudation rate from river basin sediment could be overestimated because of the bioturbation in the surficial soil layer.     

Experimental investigation on dynamic response of chamber to simulate deepwater explosive

Experimental investigation was conducted for the dynamic response of a real spherical explosive chamber that can simulate 200 m deepwater explosive loaded 10 g TNT equivalent. The vibration characteristics and dynamic strength of the chamber were analyzed by measuring the strain profiles of six characteristic points on the chamber. The research results revealed the rule of the dynamic response of the chamber on different ex- plosive loads and static pressures. It provides references for the design and development of the chamber to simu- late deepwater explosion.     

能量均衡的协作中继选择算法

为了最大化协作多中继通信系统的网络寿命,研究了在放大-转发(amplification-forward, AF)中继协作方式下网络寿命的折中优化问题,提出了一种最优能量均衡(optimal energy equilibrium, OEE)的中继协作节点选择方案。通过对AF中继每一跳接收端信噪比(signal noise rate, SNR)的计算,推导了AF两跳中继目的终端的误码率表达式,同时联合节点的剩余能量信息和信道状态信息(channel state information, CSI),利用能量均衡的思想,合理引入和设置优化因子来有效选择转发中继,延长网络寿命。理论分析和仿真结果表明,相比CSI中继选择和模糊综合评价(fuzzy comprehensive evaluation, FCE)中继选择方案,提出的中继选择方案不仅有效地提高了系统的网络寿命,而且在相同信噪比的情况下误码率性能有明显的改善。     

Frequency-domain Analysis of ECG Signal

A new simple approach to effectively detect QRS-T complexes in ECG curve is described,so as to easily get the P-wave（when AF does not happen）or the f-wave（when AF happens）．By means of signal processing techniques such as the power spectrum function,the auto-correlation function and cross-correlation function,two kinds of ECG signal when AF does or does not happen were suc cessively analyzed,showing the evident differences between them．     

基于数据包络分析的电网企业经营轨迹研究

通过分析历史状况、总结前人的研究成果,并根据电网企业运行效率的理论构建DEA模型,对我国25个省电网的企业运行轨迹进行分析．研究表明：我国大部分省份电网企业运行效率处于最优发展轨迹上,规模适度是~41＂1的显著特征;少部分省份电网企业弱劣于最优发展轨迹,规模效率较低是主要原因,规模报酬递增是他们的趋势;其余省份电网企业劣于最优发展轨迹,同时表现为规模效率较低和技术效率较低,投入冗余、产出不足是最大特征．对电网企业生产效率进行监管时要考虑到各省份电网企业之间生产力分布的不均衡性及其客观原因．