锂离子二次电池用隔膜的制备及其性质

本文采用倒相法制备了锂离子二次电池用的PVDF HFP共聚物型多孔聚合物隔膜 ,该聚合物膜具有良好的机械性能 ,其孔隙率可达 75% ,吸附电解液后增重 4 50 % ,电导率为 10 - 3S/cm ,组装成电池后表现出良好的循环性能和较低的极化率     

碳纳米管-Mm(Ni-Co-Al-Mn)5复合储氢材料的电化学性能研究

本文首次研究了碳纳米管-MmNi_3.6Co_0.7Al_0.3Mn_0.4复合储氢材料的制备及其电化学性能,在250mA/g放电的条件下,其电化学储氢量达到320mAh/g,相同条件下MmNi_3.6Co_0.7Al_0.3Mn_0.4储氢量为270mAh/g.通过循环伏安法研究氢在复合电极上电化学特性表明,碳纳米管与MmNi_3.6Co_0.7Al_0.3Mn_0.4的复合促进了氢的吸附.     

超宽禁带半导体 β-Ga2O3单晶生长突破2英寸

<正>氧化镓(β-Ga_2O_3)单晶是一种第四代超宽禁带氧化物半导体,其禁带宽度为4.8~4.9eV,具有独特的紫外透过特性(吸收截止边~260nm);击穿电场强度高达8MV/cm,是Si的近27倍、SiC及GaN的2倍以上,巴利加优值分别是SiC、GaN的10倍、4倍以上,并且可以采用熔体法生长大尺寸体单晶,因此β-Ga_2O_3已成为超高压功率器件和深紫外光电子器件的优选材料之一。由于其在军事、能源、医疗、环境等领域的重要应用价值,近年来,氧化镓材料及器件的研究与应用成为当前美国、日本、德国等国家的研究热点和竞争重     

Crystal growth and spectral properties of Tb:Lu_2O_3

The crystal growth,x-ray diffraction pattern,absorption spectrum,emission spectrum,and fluorescence lifetime of a Tb:Lu_2O_3 single crystal were studied.Excited at 483 nm,the peak absorption cross-section was calculated to be 3.5×10~(-22)cm~2,and the full width at half maximum was found to be 2.85 nm.The Judd-Ofelt(J-O)intensity parameters ?_2,?_4,and ?_6 were computed to be 3.79×10~(-20)cm~2,1.30×10~(-20)cm~2,and 1.08×10~(-20)cm~2,with a spectroscopic quality factor ?_4/?_6 being 1.20.The emission cross-sections of green emission around 543 nm and yellow emission around 584 nm were calculated to be 9.43×10~(-22)cm~2 and 1.32×10~(-22)cm~2,respectively.The fluorescence lifetimeτexp of ~5D_4 was fitted to be 1.13 ms.The data suggest that the Tb:Lu_2O_3 crystal could be a potential candidate for green and yellow laser operation.     

位移浅水内孤立波

研究两层浅水系统中的内孤立波，该系统由两层常密度不可压缩无黏性水组成。利用Lagrange坐标和Hamilton原理，推导了两层浅水系统的位移浅水内波方程，并进一步导出了两层浅水系统的位移内孤立波解。数值实验表明，位移内孤立波与经典的KdV内孤立波吻合很好，说明Lagrange坐标和Hamilton方法适用于内波分析，可以为构造内波分析的保辛方法提供一种途径。     

Ground-state energy of beryllium atom with parameter perturbation method

We present a perturbation study of the ground-state energy of the beryllium atom by incorporating double parameters in the atom's Hamiltonian. The eigenvalue of the Hamiltonian is then solved with a double-fold perturbation scheme,where the spin-spin interaction of electrons from different shells of the atom is also considered. Calculations show that the obtained ground-state energy is in satisfactory agreement with experiment. It is found that the Coulomb repulsion of the inner-shell electrons enhances the effective nuclear charge seen by the outer-shell electrons, and the shielding effect of the outer-shell electrons to the nucleus is also notable compared with that of the inner-shell electrons.     

Single-walled Carbon Nanotubes as Electrode Materials for Supercapacitors

Large-scale synthesized single-walled carbon nanotubes （SWNT） prepared by electric arc discharge method and a mixture of NiO and Y2O3 as catalyst have been used as electrode materials for supercapacitors. N2 adsorption/desorption measurement shows that the SWNT is a microporous and mesoporous material with specific surface area 435 m^2·g^-1. The specific capacitance of the nitric acid treated SWNT in aqueous electrolyte reaches as high as 105 F/g, which is a combination of electric double layer capacitance and pseudocapacitance. The SWNT-based capacitors also have good charge/discharge reversibility and cycling perdurability.     

位移浅水内孤立波

研究两层浅水系统中的内孤立波,该系统由两层常密度不可压缩无黏性水组成。利用Lagrange坐标和Hamilton原理,推导了两层浅水系统的位移浅水内波方程,并进一步导出了两层浅水系统的位移内孤立波解。数值实验表明,位移内孤立波与经典的KdV内孤立波吻合很好,说明Lagrange坐标和Hamilton方法适用于内波分析,可以为构造内波分析的保辛方法提供一种途径。     

钯催化合成2-(2,4-二氟苯基)吡啶

以Pd(OAc)2为主催化剂,PPh3为配体,2-溴(氯)吡啶和2,4-二氟苯硼酸通过Suzuki偶联反应合成了2-(2,4-二氟苯基)吡啶,产率＞90%,其结构经1H NMR,19F NMR和IR确证.     

基于期货、期权与现货组合的采购决策和风险控制研究

针对企业大宗原材料采购容易受到上游价格和下游需求的不确定性影响这一问题,本文以制造商(或分销商)多阶段采购决策为研究对象,建立了包含期货、期权和现货三种采购方式的多阶段组合采购决策模型,以此来应对采购中的价格风险和库存风险.结合某钢构厂原材料采购问题,采用蒙特卡罗仿真方法进行求解.通过对比组合方式与现货方式的求解结果,证明了组合采购方式能够在各种采购环境下为采购商带来更高更稳定的利润,所提出的组合采购决策模型能够有效的规避风险.