Mossbauer study of brucite (Mg, Fe) (OH)2

Mossbauer spectra of brucite mineral from Shanxi in China were measured over a temperature range from 12 K to 500 K. Each spectrum consists of a dominant ferrous doublet and an additional ferric doublet. The most interesting result is the temperature dependence of the line broadenings atT<400 K, with the negative velocity line always more broadened than the positive one. A possible explanation of these systematic broadenings is the presence of a small magnetic perturbation in brucite. Xu Binfu: born in 1955. Associate professer     

新型二维层状结构磷酸锌钴的合成与晶体结构

水热体系中制备了(C4H12N2)·[Zn(2-x)Cox(PO4)2](x=0.874)单晶,并对其结构进行了解析.该化合物由ZnO4和PO4四面体通过共顶点相连,形成二维层状结构;双质子化的结构导向剂哌嗪排列在无机层之间.该晶体属于三斜晶系,空间群为PI,Mr=403.20,a=0.514 04(12)nm,b=1.076 0(3)nm,c=1.079 3(3)nm,V=0.541 1(2)nm3,Z=2,d=2.475 g/cm3,μ=4.167 mm-1,R=0.031 3,Rw=0.080 9.     

Quantum size effect of the magnetism of an electron in a metal layer of the layered compounds M/I/M/I…

The energies and the magnetization of an electron in a piece of metal in the structure of Metal/Insulator/Metal/Insulator… (M/I/M/I…), in a magnetic field, at high temperature, and in range of quantum size thickness of the piece of metal layer have been obtained. The results show that when the thickness of the metal layer becomes smaller, the orbital magnetism of the charged particles which collide with the wall of the metal layer is to vary from diamagnetism to paramagnetism. The smaller the thickness of the metal layer becomes, the more particles will collide with the boundary of the metal layer, and then the paramagnetism becomes stronger. Finally, when the thickness of the metal layer becomes very small (<100 nm), all of the orbital diamagnetism will reverse to paramagnetism, and then the paramagnetization will be almost a maximum constant. Foundation item: Supported by the National Natural Science Foundation of China (59602004) Biography: Shen Gou-jin (1959-), male, Associate professor, research direction: theoretical physics.     

分层介质结构介质剖面重建的唯一性问题

该文分析讨论了圆柱面分层介质结构介质剖面重建的唯一性问题，文中提出了一种以相关的线性代数方程取代原非线性代数方程的线性化方法，该线性化方法对原始的积分方程无严格的要求，可以在一般意义上解决任意几何形状分层介质结构介质剖面重建的唯一性问题。     

层状岩体各向异性损伤模型及验证

为推导层状岩体各向异性损伤模型,研究损伤对层状岩体力学参数的劣化程度,通过层面局部坐标系下的两组损伤变量对横观各向同性弹性本构方程进行修正,经坐标转换形成整体坐标系下的损伤本构方程,采用室内单轴压缩试验和三轴压缩试验结果验证该损伤模型的合理性。研究结果表明:(1)通过层状岩体损伤模型计算所得的强度和变形参数均可较好地反映试验结果,并具有各向异性,计算出的应力-应变曲线与试验结果吻合较好;(2)通过该损伤模型,仅需层面倾角为0°和90°时的两组变形参数即可求解各倾角下的应力-应变关系;(3)通过对摩尔-库伦屈服准则中的参数进行损伤劣化修正,可对试件破坏后的力学行为进行预测。研究结果对于层状岩体的试验研究、理论计算和工程建设具有一定的指导意义。     

循环流化床内生活垃圾颗粒冷态分层特性分析

对城市生活垃圾循环流化床焚烧炉炉内冷态流场及生活垃圾颗粒冷态分层特性进行了数值模拟.结果表明:密相区和稀相区的流场存在较大差异,密相区u、v、z值较稀相区大得多,湍流强度大,扰动强烈;稀相区流场横向扰动很弱.不同粒径的垃圾颗粒在炉内存在明显的分层现象,流化风速1.5～2 m/s时,小于1 mm的垃圾颗粒集中在炉膛上部,大于5 mm的垃圾颗粒沉积到炉膛底部.风速从0.8 m/s增加到2 m/s时,风速越小、粒径差异越大,分层越明显.随着风速的增加,不同粒径垃圾颗粒分布趋于均匀,分层现象减弱.当风速小于1 m/s,炉内整体流态化及循环状况较差,1.5～2 m/s的流化风速对生活垃圾流化床较为适合.     

波浪作用下抛石基床直立堤沙质底床中孔隙水压力响应

利用波浪水槽试验,对波浪作用下抛石基床直立堤沙质底床的孔隙水压力响应进行了研究．试验中观测了在不同波高、周期、水深和泥沙粒径等条件下,自由底床和有抛石基床防波堤的土体孔隙水压力的变化．试验结果分析表明,随着波高和周期的增大,孔隙水压力幅值增大;随着水深的增大,孔隙水压力幅值减小．建堤后,底床中的孔隙水压力会增大,有效应力会降低,对防波堤的稳定性会造成严重影响．同时试验结果也表明,把基于Biot固结理论的多孔弹性介质模型用于研究波浪作用下海床的动力响应是合理的．     

锂离子电池正极材料LiNiO2及其掺杂化合物

从制备方法、比容量、循环性能,以及安全性能等方面对锂离子电池正极材料LiNiO2及其掺杂化合物有关的研究进展进行讨论,并提出今后研究的方向和途径。     

Supermolecular layered double hydroxides

Research progresses in the layered double hydroxides [M _(1-x ^)/2+ M _x ³⁺ (OH)₂] ^x+ A _x ^n/n− ·mH₂O intercalated with metal coordinate ions or oxometalates in the last ten years are reviewed. These layered double hydroxides are mainly intercalated with polyoxometalate (POM) ions, a LiAl-LDH photochemical assembly containing TiO₂ and CH₃(CH₂)₁₂COO⁻ anions, together with Zn(TPPC) (porphyrin derivate) and macrocyclic ligand-containing porphyrin derivate anions. Emphasis is put on the synthesis methods for intercalation of the anions into the interlayer regions, the characterization techniques and structures for the layered compounds and the newest research progress in the fields such as catalysis. The review also forecasts the prospects of the field.     

Internet上流媒体实时多点播放质量适应机制研究

在视频单点播放质量适应机制和VOD系统的代理缓冲机制的基础上,就Internet上流媒体的实时多点播系统提出了一种以分层编码为模型的代理缓冲质量适应机制,着重讨论了数据层的增加和丢弃算法及数据层在代理缓冲空间中的分配和替代过程,实例分析表明该机制能有效地提高各接收方的播放质量并使得播放过程具有平滑性。