PuO分子X5Σ-态的势能函数及热力学函数的量子力学计算

在Pu的相对论有效原子实势近似和O原子6-311G^*全电子基函数下,用quadratic configuration interaction of singlely and doublely substitution(QCISD)方法计算了PuO分子基态X⁵Σ^-的Murrell-Sorbie解析势能函数和热力学函数,得到R_e,D_e,B_e,α_e,ω_关键词：     

紫外光散射通信系统的数据传输速率影响因素的研究

无线紫外光局域通信是在短距离内实现全方位信息安全传输的有效途径之一,其中数据传输速率是该类通信系统的重要技术指标。从常用的紫外收发通信系统结构出发,研究无线紫外光局域通信数据传输速率的影响因素。研究结果表明：大气信道和紫外光源的选择对系统数据传输速率影响较大;由于大气散射信道的多径时延,系统的最大调制速率受到限制,当通信距离较短或天气环境较好时,系统的最大调制速率较高;紫外光源中,低压汞灯最大调制速率20kHz,紫外LED最大调制速率为几兆赫兹左右。相关研究成果为高速紫外光局域网络的设计与应用提供了参考。     

新型超导体MgB2的热电势和电阻率研究

测量了MgB₂的热电势和电阻率与温度的依赖关系.在100K—300K区间,热电势呈近似线性温度依赖关系,其斜率为正,表明载流子为空穴型且与能带贡献的图像相一致.与此对应,在此温区电阻率呈T²依赖关系.在100K以下,热电势和电阻率各自转变了其高温区的温度依赖关系.热电势在超导转变温度T_c(零电阻366K)到100K间有一宽峰,具有声子曳引峰的特征,表明电子-声子相互作用很强.估算了一些重要的参数,如带米能E_F、能带宽度 关键词： 新型超导体 热电势 电阻率     

微量钙的测定方法研究进展

介绍了1995-2006年期间测定微量和痕量钙的方法,如电感耦合等离子体-原子发射光谱法、原子吸收光谱法以及离子色谱法等的工作原理和特点,并说明了其测定微量钙的应用领域。并对微量钙的测定技术进行了展望(引用文献55篇)。     

Anomalous Optical and Electronic Properties of CaTiO3 Perovskites

With the help of the first-principles full potential linearized augmented plane wave method, absorption coefficients, reflectivity, dielectric behavior and electronic properties, including electronic energy bands, density of states and charge density distributions, are studied for the tetragonal and cubic CaTiO3. By considering the thermal expansion effects, an approximate method is proposed for the study of the stability of ground state and a tendency of phase transition, based on the minimum free energy principle. Subsequently, numerical calculations are carried out by using the first-principles perturbation method. We demonstrate that the high-temperature phase is cubic. It is shown that optical spectra in tetragonal phase exhibit single-peak feature and differ from multi-peak character in cubic. We find that strong orbital hybridization results in the co-valent bonds between Ti 3d and O 2p electrons and forms two-type dipoles (Ti-O1 and Ti-O2) in tetragonal, while the Ti-O dipoles are identical in cubic. It is argued that crystal structure determines the dipole distributions and leads to some electron states among which the dipole-dipole transition forbidden is a key, causing such anomalous optical phenomena with the insulator characteristics. The predicted charge density distribution and the tendency of phase transition from tetragonal to cubic are in good agreement with experimental observations.     

煅烧石油焦及六方氮化硼对摩阻材料摩擦磨损性能的影响

在酚醛树脂基摩阻材料中分别添加煅烧石油焦（CPC）及六方氮化硼（hBN）作为摩擦改性剂,研究了2种摩擦改性剂对酚醛树脂基摩阻材料的力学性能和摩擦磨损性能的影响,通过热失重试验分析了复合材料的耐温性能,并利用扫描电子显微镜观察复合材料的磨损表面形貌．结果表明：当hBN体积分数为10％～15％时,摩阻材料与树脂基体的粘接强度最强且能够明显降低复合材料的硬度,有助于在摩擦界面生成均匀牢固的润滑膜而起到降低磨损率、稳定摩擦系数的作用;当hBN体积分数超过15％时,由于hBN过饱和及其与树脂基体的相容性差,导致摩阻材料机械强度下降,磨损率增大;随着CPC含量增加,摩阻复合材料的机械强度增加,摩擦磨损性能降低;CPC和hBN的体积分数为12％时能够不同程度地提高摩阻材料的耐温性能及降低其对速度和载荷的敏感性,且含12％hBN摩阻材料的热稳定性最佳,其摩擦磨损性能对速度和载荷的敏感性最小,     

酰胺基多硫化物在菜籽油中的摩擦磨损特性研究

采用2种不同链长胺合成出含酰胺基有机多硫化物(其中BDBS和BDIOS分别为二正丁胺和二异辛胺合成的多硫化物),利用四球摩擦磨损试验机评价其在可生物降解菜籽油中的极压、抗磨及减摩性能,采用扫描电子显微镜和X射线吸收精细结构光谱仪分析上述有机多硫化物的摩擦化学作用机理.结果表明,所合成的2种酰胺基多硫化物均能够提高菜籽油的最大无卡咬负荷pB值,具有抗磨效果且BDBS在所测试负荷下的抗磨效果优于菜籽油和BDIOS;各添加剂在测试负荷范围(196～490 N)内均能够降低菜籽油的摩擦系数,且BDBS的减摩性能优于BDIOS,其磨损表面虽呈现出腐蚀磨损特征,但相比菜籽油的磨斑而言,含添加剂的菜籽油润滑体系下的磨斑表面犁沟明显变浅;酰胺基多硫化物BDBS在中等负荷条件下形成的摩擦膜的最外层主要由吸附态烷基二硫化物和少量FeSO4组成,次表面主要由FeS2和少量FeSO4组成,而摩擦膜本体则由FeS2组成.     

Phonon Transport and Thermal Conductivity in a Four-Terminal Structure

With the help of scattering-matrix method, the acoustic phonon ballistic transmission and the thermal conductivity are studied detailedly in a four-terminal structure. We find that the transmission coefficients and the reduced thermal conductance for each region sensitively depend on geometric parameters, and are of quantum character, but the reduced total thermal conductance for all regions seems independent of structure parameters when the temperature is not very low. Our results show that one can control the thermal conductivity for each region to match practical requirements in devices by adjusting the geometric parameters.     

Monte Carlo Study of Planar Rotator Model with Weak Dzyaloshinsky-Moriya Interaction

With the help of an improvement Monte Carlo method, the Berezinskii-Kosterlitz-Thouless phase transition arising in two-dimensional planar rotator model with weak Dzyaloshinsky-Moriya (DM) interaction is investigated. The effects of the DM interaction on specific heat, susceptibility, and magnetization are simulated. The critical temperature of transitions is determined by the so-called Binder cumulant and the susceptibility of finite-size scaling. We find that the chiral Z2 symmetry reduced by the DM interactions plays an important role in a two-dimensional XY spin system,typically, the critical temperature is sensitive to weak DM spin couplings.     

水平直线上Dirichlet级数的(p,q)(R)级和(p,q)(R)型

研究Dirichlet级数∑∞n=1 ane-λns所确定的函数f(s)在水平直线上级数的(p,q)(R)级和(p,q)(R)型,得出在某些"缺项"的条件下,Dirichlet级数∑∞n=1ane-λns所确定的整函数f(s)在水平直线上的(p,q)(R)级和(p,q)(R)型等于其在全平面上的(p,q)(R)级和(p,q)(R)型.