Resistivity－temperature characteristics of sol gel YBa2Cu3Oy samples synthesized in flowing oxygen atmosphere

The relationship of resistivity versus synthesizing temperature of sol gel YBa_2Cu_3O_y samples was studied when prepared under flowing oxygen conditions. A set of high-temperature ρ－T curves was obtained for the whole process. After the sample finished the test measuring, its resistivity was ρ_{300}=9.83×10^{-3 }Ω·cm at room temperature. The ρ－T curve also showed that the orthorhombic－tetragonal phase transformation of sol-gel YBa_2Cu_3O_y sample occurred at 581℃ for the sample in the rising temperature process, but at 613℃ in the cooling process, lower than that of the samples made by using the conventional powder metallurgy methods.     

互补型自适应滤波器在心磁信号处理中的应用

将心磁信号从干扰噪声中加以提取并有效地消除噪声干扰是心磁信号处理中尤为重要的环节 .从改进算法的角度出发，提出互补型自适应滤波器结构以实现心磁信号的消噪处理.该滤波器针对心磁这类非平稳信号进行设计，有效地解决了常规自适应滤波器应用于心磁信号处理时收敛速度和稳态误差的矛盾.通过仿真实验和心磁实验结果表明，该算法能有效地消除心磁信号的背景噪声和工频干扰噪声.同时该算法也可用于其他非平稳信号的消噪处理. 关键词： 自适应滤波 心磁图 最小均方误差     

An optical study of the D-D neutron irradiation-induced defects in Co-and Cu-doped ZnO wafers

Room-temperature photoluminescence and optical transmittance spectroscopy of Co-doped(1×1014,5×1016,and 1×1017cm-2) and Cu-doped(5×1016cm-2) ZnO wafers irradiated by D-D neutrons(fluence of 2.9×1010 cm-2) have been investigated.After irradiation,the Co or Cu metal and oxide clusters in doped ZnO wafers are dissolved,and the wu¨rtzite structure of ZnO substrate for each sample remains unchanged and keeps in high c-axis preferential orientation.The degree of irradiation-induced crystal disorder reflected from the absorption band tail parameter(E0) is far greater for doped ZnO than the undoped one.Under the same doping concentration,the Cu-doped ZnO wafer has much higher irradiation-induced disorder than the Co-doped one.Photoluminescence measurements indicate that the introduction rate of both the zinc vacancy and the zinc interstitial is much higher for the doped ZnO wafer with a high doping level than the undoped one.In addition,both crystal lattice distortion and defect complexes are suggested to be formed in doped ZnO wafers.Consequently,the Co-or Cu-doped ZnO wafer(especially with a high doping level) exhibits very low radiation hardness compared with the undoped one,and the Cu-doped ZnO wafer is much less radiation-hard than the Co-doped one.     

Hcp-icosahedron structural transformation induced by the change in Ag concentration during the freezing of （CoAg）561 clusters

The synergy effect of alloy elements in bimetallic clusters can be used to tune the chemical and physical properties. Research on the influences of alloy concentration and distribution on the frozen structure of bimetallic clusters plays a key rolc in exploring new structural materials. In this paper, we study the influence of Ag concentration on the frozen structure of the （AgCo）561 cluster by using molecular dynamics simulation with a general embedded atom method. The results indicate that tt~e structure and chemical ordering of the （AgCo）561 cluster are strongly related to Ag concentration. Hcp-icosahedron structural transformation in the frozen （CoAg）561 cluster can be induced by changing Ag concentration. The chemical ordering also transforms to Janus-like Co Ag from core-shell Co-Ag.     

6p2阶的三度半对称图

正则图G 称为G-半对称图, 如果G 的自同构群A := AutG 有一个子群G在G 的边集上传递, 但在其点集上不传递, 特别地, 当G= A时Γ 称为半对称图. 本文旨在考察素数度的(G-)半对称图. 首先给出了素度数的(G-)半对称图的群论刻画, 其次对6p²阶的三度半对称图进行了完全分类, 其中p是奇素数.     

环上的广义导子与Von Neumann代数上的P-核值保持映射

设Ａ是Ｂ（Ｈ）的子代数，ψ是Ａ到Ａ的线性映射，且对Ａ中的每个正交投影算子ｐ，有ψ（ｐ）（ｋｅｒｐ）ｒａｎｐ，则称ψ是Ａ到Ａ的Ｐ－核值保持映射，本文主要得到如下结果：每个２－非绕的半素环上的广义Ｊｏｒｄａｎ导子都是广义导子；每个ＶｏｎＮｅｕｍａｎｎ代数上的范数拓扑连续的Ｐ－核值保持映射是广义内导子．     

三倍频激光等离子体X射线转换研究

利用“星光Ⅱ”高功率激光装置三倍频激光（波长０.３５μｍ,能量５—９０Ｊ,焦斑直径约２００μｍ,脉冲宽度４００—８００ｐｓ）辐照多种材料（Ｃ,Ａｌ,Ｃｕ,Ａｕ）靶,对于不同激光功率密度,研究软Ｘ射线转换和发射能谱．结合０.３５μｍ激光辐照Ａｌ靶的质量烧蚀率和等离子体喷射速度与激光功率密度的定标关系进行数值模拟,对于激光功率在１０^１３—１０^１５Ｗ／ｃｍ²理论模拟结果与实验结果符合得很好 关键词：     

氢气在炭狭缝微孔内吸附的预测

通过边界的平均场近似,推导二平板狭缝孔格子理论Ono-Kondo吸附等温方程。利用格子模型特性和微观物理学理论,计算氢分子在石墨平面的最大吸附容量。比较由氢分子在石墨平面二典型聚集状态标定的Ono-Kondo方程,并用预测精度较高的方程计算了与文献相同条件下的吸附等温线。在比较了计算结果、试验结果和GCMC分子模拟结果后,对Ono-Kondo吸附等温方程的特点、理论基础作了分析,指出了方程的适用范围。     

三(4-甲基苯甲酰基)纤维素酯的合成及其涂敷手性固定相的制备和表征

以微晶纤维素为原料合成三（４－甲基苯甲酰基）纤维素酯,涂敷在平均粒径为６μｍ、平均孔径为１５ｎｍ、比表面积为６７ｍ２／ｇ的堆积硅珠上,制备成手性固定相。用扫描电子显微分析考察了固定相的表面形貌。用高效液相色谱法分离了（±）－α－苯乙醇对映异构体,考察了洗脱液正己烷／异丙醇（９８∶２,Ｖ／Ｖ）的流速和洗脱液的组成对（±）－α－苯乙醇对映异构体分离的影响。     

超声脉冲背向散射法测量悬浊液浓度的研究

本文报导了在不同浓度和不同粒径的水泥浆悬浊液中超声脉冲背向散射讯号的数字特征，主要是幅域和频域特征。对于不同的浓度范围，可以取不同的背向散射讯号特征量（如散射声强或散射衰减）来表征悬浊液的浓度和粒径，对于低浓度范围，相对散射声强与浓度有较好的线性关系，对于高浓度范围，声强的散射衰减与浓度有较好的线性关系，高浓度与低浓度之间存在着过渡区域，在此区域内，散射声强随浓度的增加与散射衰减随浓度的增加呈动态平衡，因而在过渡区域内散射声强将与浓度无关，并与频率或粒径有关，当频率一定时，可确定粒径分布。