Surface Gravity on the Horizon of η- ξ Spacetime

We investigate the two methods of defining the surface gravity ,κ on the horizon, which are the metric definition and the definition given by the spacetime conformal method. It is found that the latter is of greater generality. By this method, we find that ,κ of η- ξ spacetime is equal to the exponent factor α in the coordinate transformation, which confirms the argument that η- ξ spacetime can be considered as the background spacetime for finitetemperature field theories. The reasons why the metric definition of ,κ can not be applied in η- ξ spacetime are presented.     

The structural,elastic, and electronic properties of ZrxNbl-xC alloys from first principle calculations＊

The structural, elastic, electronic, and thermodynamic properties of ZrxNbl xC alloys are investigated using the first principles method based on the density functional theory. The results show that the structural properties of Zr~.Nb1 xC alloys vary continuously with the increase of Zr composition. The alloy possesses both the highest shear modulus （215 GPa） and a higher bulk modulus （294 GPa）, with a Zr composition of 0.21. Meanwhile, the Zr0.2! Nb0.79C alloy shows metallic conductivity based on the analysis of the density of states. In addition, the thermodynamic stability of the designed alloys is estimated using the calculated enthalpy of mixing.     

一种新的大学物理授课方法

本文提出了大学物理的一种新授课方法,旨在加强教、研结合,强化大学物理教学对学生综合素质的培养,同时提高教师的科研水平.     

基于过程化管理和考核的大学物理混合式教学实践

针对传统大学物理教学中教师主导课堂,学生被动接受而缺乏主动性,学生平时投入少,考试前突击学习等典型问题,提出通过过程化管理和考核,线上和线下教学相结合的方式,提升学生的学习主动性,促进学生的个性化、深层次学习.对课程内容、考核方式进行了探究和改革,在将教学内容模块化的基础上,建立了一套包括模块预习考试、模块测试、在线讨论和期末考试相结合的多元化考核方式,最大程度地让学生参与到整个教学过程,达到提升大学物理教学质量,提高学生自主学习能力的目的.     

晶粒大小对ZSM-5分子筛甲醇制低碳烯烃催化性能的影响

对三种HZSM-5分子筛进行Ca改性,获得两组酸性接近的催化剂,考察了晶粒大小对甲醇制低碳烯烃(MTO)反应的影响。通过进一步与Na改性的比较,探讨了Ca在催化反应中的作用。采用扫描电镜(SEM)测定晶粒大小及形貌,氨气程序升温脱附(NH3-TPD)及吡啶红外吸附(Py-IR)表征催化剂的酸性。MTO催化性能测定结果表明,HZSM-5的低碳烯烃选择性较低且下降较快,催化活性降低也快;Ca改性降低酸性,提高了低碳烯烃选择性和催化稳定性;晶粒大小主要影响催化稳定性,小晶粒分子筛催化剂稳定性更好。高Ca含量改性效果更好;钠改性也提高了低碳烯烃选择性,但其稳定性较差。对于HZSM-5和Ca/HZSM-5,小晶粒的催化剂具有较好的催化稳定性。提出Ca参与了催化反应,MTO是一个酸碱协同作用的催化过程。     

李欣并代数的性质及其应用

通过讨论李欣并代数X=X1U1X2与它的两个子代数X1、X2之间的关系,其中X1是BCK-代数,X2是BCI-代数,得到了李欣并代数X分别是交换、正关联、关联的BCI-代数的充要条件.从而确定了所有阶n≤5的真BCI-代数按交换性、正关联和关联性的分类.     

The structural,elastic,and electronic properties of Zr_x Nb_(1-x)C alloys from first principle calculations

The structural,elastic,electronic,and thermodynamic properties of Zr x Nb1-x C alloys are investigated using the first principles method based on the density functional theory.The results show that the structural properties of Zr x Nb1-x C alloys vary continuously with the increase of Zr composition.The alloy possesses both the highest shear modulus(215 GPa)and a higher bulk modulus(294 GPa),with a Zr composition of 0.21.Meanwhile,the Zr0.21Nb0.79C alloy shows metallic conductivity based on the analysis of the density of states.In addition,the thermodynamic stability of the designed alloys is estimated using the calculated enthalpy of mixing.     

First-Principles Study of Structural Stabilities, Electronic and Optical Properties of SrF2 under High Pressure

An investigation of structural stabilities, electronic and optical properties of SrF2 under high pressure is conducted using a first-principles calculation based on density functional theory （DFT） with the plane wave basis set as implemented in the CASTEP code. Our results predict that the second high-pressure phase of SrF2 is of a Ni2In- type structure, and demonstrate that the sequence of the pressure-induced phase transition of SrF2 is the fluorite structure （Fm3m） to the PbC12-type structure （Pnma）, and to the Ni2In-type phase （P63/mmc）. The first and second phase transition pressures are 5. 77 and 45.58 GPa, respectively. The energy gap increases initially with pressure in the Fm3m, and begins to decrease in the Pnma phases at 30 GPa. The band gap overlap metallization does not occur up to 210 GPa. The pressure effect on the optical properties is discussed.     

关于拟Koszul模的注记

对于每个诺特半完全代数A上的模M,都有一个谱序列E_（pq）～＊（M）与之相对应.本文证明了有限生成A-模M是拟Koszul的当且仅当谱序列E_（pq）～＊（M）的第E～2层是平凡的.与之对偶,本文叙述了余拟Koszul模情况下的类似结果.     

AS-Gorenstein代数的Yoneda代数

令A为诺特基本k-代数,设J为其Jacobson根且半单代数A/J同构于有限个k的直积.证明了如果A是AS-Gorenstein代数,则其Yoneda代数Ext*A(A/J,A/J)是Frobenius代数;如果A的内射维数injdimAA=d,则函子ExtdA(-,A)是可表示的.