RSFQ的初步研究

RSFQ应用于高速电子计算机是近年来活跃在低温超导电子学领域的新兴课题。文中从约瑟夫逊效应的等效模型出发 ,阐述了 RSFQ电路的基本基理及基于节点约瑟夫逊相位的数值模拟方法 ,并把它用于一个 RSFQ单向缓冲器的瞬态分析 ,给出了其相位和电压波形     

用液压测功的研究

本文介绍了一种测定发动机输出功率的方法。     

Structural study of the ferroelectric instability in SnPSe

The structural change occurring in between the paraelectric and the ferroelectric phases is investigated by means of X-ray diffraction. Details of the structure in both phases are obtained and the role of the lone pair is discussed in the light of structural data. In agreement with the 2/ m to m symmetry lowering, polar displacements are found within the m plane away from a particular crystallographic direction but antiparallel displacements occur also. These results are discussed in the frame of the phenomenological theory which predicts a particular temperature dependence of the dielectric polarization in this crystal. Received: 10 July 1998     

The seasonal variations of δ~(18)O , Cl~- , Na~+ , NO_3~- and Ca~(2+) in the snow and firn recovered from Princess Elizabeth Land, Antarctica

Snow and firn samples recovered from two snow pits (2.5 and 4.5m deep) and one 50-m firn core along the route of the 1996/1997 Chinese First Antarctic Inland Traverse Expedition in Princess Elizabeth Land, East Antarctica, have been measured for chemical composition and oxygen isotope ratio. In the two snow pits, the variations of NO3- are partly in phase with that of δ18O, while the variations of Cl~ and Na+ are in inverse phase with that of δ18O. The variations of CI- , Na+ , NO3- and δ18O show obvious seasonal variations and annual stratag-raphy. However, with the depth increasing, the seasonal variations of δ18O are gradually smoothed below 3 m (corresponding to about 10-year mass accumulation) in depth while the seasonal variations of Cl- , Na+ and NO3- are kept fairly well in the whole profile of the 50-m firn core (corresponding to about 250-year mass accumulation). The results provide a useful tool for dating the snow stratum in this region. On the contrary, no obvious seasonal variations of Ca2 + are found in the profiles.     

县域土地利用的可持续性评价──以广西壮族自治区为例

该文提出了县域土地利用的可持续性评价的评价指标体系和评价方法,并对广西壮族自治区的80个县、县级市进行了土地利用可持续性评价。     

贵州民族药杨梅叶抗菌作用的实验研究

报道了采用管碟法对矮杨梅４ 种类型植物叶的水煎剂体外抗菌实验的研究,其结果表明对Ｇ＋ 金黄色葡萄球菌有抑菌作用,对Ｇ－ 大肠肝菌,Ｇ－ 霍乱弧菌,Ｇ－ 福氏痢疾杆菌,Ｇ－ 伤寒杆菌无抑菌作用。不同类型矮杨梅叶对细菌具选择性抑制作用,不同类型矮杨梅叶对同一细菌抑菌能力不同。     

凸特征的凹参数定义

从特征设计的角度看 ,机械加工的过程实际上是切除所有凹特征的过程 ,因此凹特征在工艺规程中与切削过程一致 ,而凸特征一般都要转换成相应的凹特征才能进行处理 ,这种转换往往比较繁琐 .本文在分析了凸特征分解法的优缺点后 ,提出了一种新的“凸特征凹参数定义”方法 ,对凸块、圆柱凸台和筋等典型的凸特征进行了详细的凹参数定义的讨论 ,并给出了我们在进行组合夹具自动设计中用到的凸特征的实例 ,进一步分析了此方法的特点和实用价值     

心理学方法在珠算教学中的应用

掌握好珠算这种便捷的运算方法,对培养思维和提高运算能力大有好处。笔者在教学实践中,逐步发现学生的心理状态是影响运算能力的最主要因素。本文总结了在教学中应用心理学方法,对学生的各种不健康学习心理进行了行之有效的矫正。     

基于码相关测距的MPSK性能分析

以8PSK为例介绍了MPSK信号的调制方式和解调系统。针对要求的系统提出了一种新的码相关测距方法,即利用解相关峰来控制起止计时脉冲。并设计了对应的解调系统框图。在此测距方法的基础上,对8PSK和BPSK进行了信噪比和精度的理论对比分析和实验仿真。仿真结果表明:在信噪比方面,同样的采样频率下,8PSK相对于BPSK信噪比下降很大;在精度上,8PSK相对于BPSK有所提高。为8PSK用于码相关测距提供了一定的借鉴和参考。     

热注射法合成Cu2 SnSe3纳米晶及其光电转换性能

以乙酰丙酮铜、无水氯化亚锡为金属源,Se/OLA悬浊液为硒源,在油胺溶剂中热注射合成了Cu2 SnSe3纳米晶.采用TEM、XRD、EDS分别对典型纳米晶产物的形貌、物相和组成做了分析表征.通过不同反应温度的条件实验,研究了反应温度对最终产物的影响,探讨了相关规律.采用光电化学池评价了纳米晶的光电转换性能,结果表明Cu2 SnSe3纳米晶光电转换性能优良,表现出较好的应用前景.