【摘 要】
：
A new boron nitride polymorph,P213 BN(space group:P213),is investigated by first-principles calculations,including its structural properties,stability,elastic properties,anisotropy and electronic properties.It is found that the new boron nitride polymorph
【机 构】
：
College of Information and Control Engineering,Xi’an University of Architecture and Technology,Xi’an
论文部分内容阅读
A new boron nitride polymorph,P213 BN(space group:P213),is investigated by first-principles calculations,including its structural properties,stability,elastic properties,anisotropy and electronic properties.It is found that the new boron nitride polymorph P213 BN is mechanically,dynamically and thermodynamically stable.The bulk modulus(B),shear modulus(G)and Young\'s modulus of P213 BN are 91 GPa,41 GPa and 107 GPa,respectively,all of which are larger than that of Y carbon and TY carbon.By comparing with c-BN,the Young\'s modulus,shear modulus and Poisson\'s ratio of P213 BN show tiny anisotropy in the(001),(010),(100)and(111)planes.At the same time,in contrast with most boron nitride polymorphs,P213 BN is a semiconductor material with a smaller band gap of 1.826 eV.The Debye temperature and the anisotropic sound velocities of P213 BN are also investigated in this work.
其他文献
应急医疗联动服务体系以三环服务理论体系为基本指导,通过科学研究探索建立高效的院内卫生应急医疗联动服务体系,满足国内门诊急救困难患者日益不断增加的院内医疗应急服务质量需求.本文将目前国内医院急诊急救患者服务信息管理滞留严重,诊疗应急服务质量标准不明确,地区间医疗应急服务水平与体系建设发展不平衡等实际突出问题相结合,构建院前应急信息共享平台.
在N(2,2,0)代数中定义了 Ω-犹豫模糊关联理想,研究Ω-犹豫模糊关联理想的性质以及等价刻画,得到了 Ω-犹豫模糊关联理想的交与并的不变性的结论,讨论了 Ω-犹豫模糊关联理想与犹豫模糊关联理想的关系.
在平衡双重半拟补MS代数上引入(*)理想,(+)理想,(°)理想和(*,+,°)理想的概念,探讨平衡双重半拟补MS代数上(*)理想,(+)理想,(°)理想和(*,+,°)理想与核理想的关系,获得了(°)理想是核理想的结论.同时构造出了以(*,+,°)理想为核的最小同余关系和最大同余关系,并获得了最小同余关系和最大同余关系之间的等式关系.
The cell size variation in overdriven gaseous detonations is studied in hydrogen/oxygen and acetylene/oxygen mixtures.The local self-similarity of Mach reflection of detonations on the wedge in the far field renders the presence of a steady overdriven Mac
Failure mechanism and impact resistance of a human porous cranium are studied in detail by means of theoretical and numerical methods.It is hypothesized that pore distribution of a cranium directly affects cranial energy absorption,and a stretched beam mo
随着城市化进程的不断加快,城市水文特性发生显著变化,城市房屋建筑相对集中,大大降低了雨水滞留与调蓄功能,从而减弱了城市的综合承灾能力,即使在同等致灾条件下,会增加其损失总量.因此,为了进一步提高城市的减灾能力,建立有效的城市内涝气象预警预报系统,对减少内涝损失、提高减灾能力具有重要的现实意义.
High-precision numerical methods are utilized to study the shock waves interacting with an elliptical heavy bubble.The influence of different bubble gases(SF6 and R22)and shock intensities(Ma=1.21 and Ma=2.1)is analyzed qualitatively and quantitatively.Th
The electronic and magnetic properties of the zinc-blende aluminum nitride doped with V and Cr are studied using the density functional theory(DFT),namely the KKR-CPA-PBE method.Pure AlN is found to be a wide band gap semiconductor,and doping V and Cr sin
在现实生活中很多信息表是基于优势关系的,同时信息表中每个样本的属性值是模糊数,并且对不同的属性的重视程度也是不完全相同的,即对于不一样的属性存在着不一样的权重.针对这一情况,本文借鉴了直觉模糊序表的权重函数的想法,建立了一种在条件属性集上的权重函数,并给出了不协调的带属性权重的模糊序决策表.然后,在该决策表中定义部分一致函数和部分一致协调集,并利用部分一致可辨识矩阵的方法得到部分一致约简.最后,通过案例分析该方法的有效性.
一般而言,在邻域信息粒化的进程中,样本的邻域求解需遍历样本空间中所有的样本,并计算该样本与样本空间中所有样本间的距离.当面临样本规模急剧增加的情形时,这一粒化策略将会带来巨大的时间消耗.为解决这一问题,提出了一种快速邻域信息粒化策略.其核心是当计算样本间距离时,通过减少需要遍历的属性的个数,过滤掉那些必然不属于邻域内的样本,以达到压缩样本搜索空间并提高邻域信息粒化性能的目的 .进一步地,将这种快速邻域信息粒化应用到约简的求解进程中,在9组基准数据集上的实验结果表明,相较于传统邻域信息粒化和基于桶模型的邻域