Electronic,Vibrational, and Superconducting Properties of High-Pressure Metallic SiH4： ab initio Calculations

We extensively explore the experimentally proposed metallic structure of hcp P63 for the hydrogen rich compound, SiH4. It is found that the lattice dynamic of this structure is severely unstable. By freezing the soften mode, an orthorhombic Pbcn structure is discovered to be dynamically stable up to 226GPa. Within the conventional BCS theory, the calculated critical temperature Tc within the proposed Pbcn structure is 16.5K at 188GPa, in good agreement with the experimental result （17.5K）. Thus, we propose that the current predicted orthorhombic phase is a better candidate for the metallic phase of SiH4.     

Electrical Response of Flexible Vanadyl-Phthalocyanine Thin-Film Transistors under Bending Conditions

Flexible vanadyl-phthalocyanine （VOPc） thin-film transistors are fabricated by the weak epitaxy growth （WEG） method. The devices show a mobility of 0.5 cm2/Vs, an on/off ratio of 105 and a low leakage current of 10-9 A. The performances exhibit strong dependence on bending conditions and reversible change can be found when the bending strain is less than 1.5%. This results from the change of the trap density calculated by subthreshold slopes. The results indicate that VOPc films fabricated by the WEG method have good durability to flexing and possess great potential in flexible electronics.     

Neutron Spectroscopic Factors of ^7Li and Astrophysical ^6Li（n,γ）^7Li Reaction Rates

Angular distributions of the ^7Li（^6Li, ^6Li）^7Li elastic scattering and the ^7Li（^6Li, ^7Lig.s.）^6Li, ^7Li（^6Li, ^7Li0.48）^6Li transfer reactions at Ec.m. = 23.7 MeV are measured with the Q3D magnetic spectrograph. The optical potential of ^6Li ＋ ^7Li is obtained by fitting the elastic scattering differential cross sections. Based on the distorted wave Born approximation （DWBA） analysis, spectroscopic factors of ^7Li =^6Li n are determined to be 0.73 ± 0.05 and 0.90 ± 0.09 for the ground and first exited states in ^7Li, respectively. Using the spectroscopic factors, the cross sections of the ^6 Li（n, γ0,1）^7 Li direct neutron capture reactions and the astrophysical ^6Li（n, γ）^7 Li reaction rates are derived.     

Xe(4d~(10))(e,2e)反应三重微分截面的理论研究

采用修正后的扭曲波玻恩近似理论,计算了共面不对称几何条件下Xe(4d~(10))(e,2e)反应的三重微分截面.散射电子能量为1000 eV,敲出电子能量为20 eV,散射电子角度分别固定在2°,4°和7.5°.理论计算与Avaldi等人的实验结果和扭曲波玻恩近似理论计算进行了比较,发现出射电子之间的后碰撞相互作用较弱,极化效应在反应过程中起着重要作用.     

中国北方古建油饰彩画中绿色颜料的光谱分析

古建油饰彩画中颜料成分的分析鉴定是古建维修、保护的重要基础工作。文章利用X射线荧光分析、X射线衍射分析、扫描电镜-能谱分析技术,首次系统地分析检测了来自北京、山西、甘肃等中国北方地区的27个古建油饰彩画中的绿色颜料。结果表明,其中15个样品使用了巴黎绿这种含铜、砷的人工合成颜料,其余样品未检测出矿物颜料,显色成分应为人工合成的有机物。在所有分析样品中未检测到古代常用的绿色颜料石绿和氯铜矿的存在。该研究工作开辟了光谱分析技术应用于古建油饰彩画颜料鉴定的新领域,为该类文物分析鉴定、修复材料的选择提供了科学数据。     

Discreteness of the exterior transmission eigenvalues

In this paper we consider a kind of exterior transmission problem in which the refractive index n(x) is a piecewise positive constant. Through establishing an equivalent boundary integral system, we obtain that the set of exterior transmission eigenvalues is a discrete set. Furthermore, we prove that there does not exist a transmission eigenvalue under some conditions.     

带多项式相位的高维振荡积分算子的有界性

考虑如下的振荡积分算子:T_(m,k,n)f(x):=∫_(R~n)e~(i(x_1~2+…+x_n~2))~m(y_1~2+…+y_n~2)~kf(y)dy,其中函数f为定义在R~n上的Schwartz函数,并且满足m,k0.本文给出算子T_(m,k,n).从L~p(R~n)(1≤p∞)到L~q(R~n)有界的一个充分必要条件.此外,我们还证明了算子T_(m,k,n)把L~1(R~n)映到C_0(R~n).     

形式三角矩阵环的Gorenstein遗传性和FP-内射性

我们研究了形式三角矩阵环上模的Gorenstein(半遗传)遗传性,有限表现性和FP-内射性.给出了形式三角矩阵环是Gorenstein(半遗传)遗传的充要条件,并得出了形式三角矩阵环是n-FC环的充分条件.     

市场接纳不确定下短周期新产品产能投资研究 ——考虑竞争的投资时机与规模决策

新产品的市场接纳具有很大不确定性,传统投资理论并不适用于新产品投资。针对新产品投资中的产能投资,研究了垄断企业和有成本差异的竞争企业制定短周期新产品的产能投资时机与规模策略。给定企业“早”和“晚”两个投资时机可供选择,定义“早”投资时,企业只知道新产品市场规模的期望和方差;“晚”投资时,企业知道新产品真实的市场规模。垄断企业进入市场之前无法进行销售信息的收集,只会选择“早”投资或者不投资,给出其选择“早”投资的条件、最优产能投资规模及最大期望利润。有成本差异企业竞争的情形可以分为四种,分别给出四种情形下的最优产能投资规模及最大期望利润,并通过比较各情形下两企业的最大期望利润给出最优的产能投资时机策略。     

超竞争环境下企业困境并购定价与时机选择的期权博弈分析

基于期权博弈理论,以超竞争环境为研究背景,在多个主并企业合作的情形下,建立目标企业存在财务困境的并购模型,得出主并方的最优并购时机;并进行数值模拟分析,重点分析了代表超竞争特点的三个变量(竞争强度、竞争不确定性、企业价值损失因子)、主并企业联盟中参与者的重要程度及联盟中发生机会主义的概率、企业困境因子这六个变量对并购阈值的影响。