基于准弹性中子散射谱分析水化硅酸钙(C-S-H)中受限水的动态

研究水化硅酸钙(C-S-H)中受限水动态的一种重要手段是准弹性中子散射(quasi-elastic neutron scattering, QENS)实验. C-S-H样品的QENS谱数据可通过跳跃扩散和转动扩散模型进行分析拟合, 进而导出C-S-H样品微纳孔中水动态的相关物理参数: 不动水指数C、转动扩散系数D_r、均方位移< u² >、自扩散系数D_t及平均停留时间τ₀. 本文对水与水泥质量比为30%的C-S-H样品, 测量温度为230-280 K的QENS谱进行了分析, 得到的拟合参数可定量描述C-S-H样品内不同尺度的微纳孔中受限水随温度变化的动态过程. 转动扩散系数D_r随散射矢量Q的变化可知, Q值较大时, 水分子的转动对QENS谱影响较大. 均方位移 < u² > 随Q值的不同而变化, 其拟合值可区分C-S-H样品中的不动水、强受限水和受限水. 在Q较小时, D_t 和τ₀ 的拟合值随温度而变化, 并分别在230和240 K突然增大, 由此揭示温度为230-240 K 时, C-S-H 样品中受限水分子的动态特性发生了转变.     

水中联苯胺分析方法研究进展

对水中联苯胺的萃取方法及检测方法进行了综述。水中联苯胺的萃取方法主要为液–液萃取法和固相萃取法,检测方法主要有分光光度法、流动注射分析法、离子色谱法、气相色谱–质谱法、高效液相色谱法和高效液相色谱–质谱法等,对这些检测方法的优缺点进行了比较。对水中联苯胺的萃取技术及检测方法发展前景进行了展望。     

再论无穷多个无穷小量的乘积

对文[6]提出的质疑给出回答,表明由于不同的无穷小量趋近于0的速度有快有慢,因此无穷多个无穷小量的乘积∏∞k=1{x_n~(k)}∞n=1,有可能不是无穷小量(其中对每个正整数k,{x_n~(k)}_(n=1)~∞表示极限为0的数列),而验证∏∞k=1{x_n~(k)}∞n=1是否是无穷多个无穷小量的乘积,只需验证对每个正整数k,当n→+∞时,{x_n~(k))_(n=1)~∞是否趋近于0,而无需考虑函数列{{x_n~(k)}_(n=1)~∞}_(k=1)~∞的极限limk→∞x_n~(k)是不是无穷小量.进而,对无穷多个无穷小量的乘积是无穷小量或不是无穷小量给出了一些充分条件,     

晶面选择性生长对球形氢氧化镍形貌及电化学活性的影响

在相同的物理化学条件、不同晶化时间的条件下,采用化学沉淀法制备球形氢氧化镍晶体并应用SEM技术分别考察制得样品的形貌。研究表明：在相同的物理化学条件下,随着晶化时间的增加,样品的微观形貌由不规则状晶体变为完整的球状晶体。结合XRD表征结果分析得出：（001）晶面在晶化时间达到3 h时生长到了一个稳定的状态,并不随着晶化时间的增加而有明显的变化,但（100）与（101）晶面随晶化时间的增加继续生长,当晶化时间达到12 h时氢氧化镍的相对结晶度最大,（100）与（101）衍射峰强度高且峰形尖锐,说明氢氧化镍晶体的结构规整性增强。本文还讨论了氢氧化镍生长结晶过程中晶面选择性生长对晶体形貌及电化学性能的影响。     

Solving the initial condition of the string relaxation equation of the string model for glass transition:part-Ⅱ

The string model for the glass transition can quantitatively describe the universal α-relaxation in glassformers. The string relaxation equation (SRE) of the model simplifies the well-known Debye and Rouse--Zimm relaxation equations at high and low enough temperatures, respectively. However, its initial condition, necessary to the further model predictions of glassy dynamics, has not been solved. In this paper, the general initial condition of the SRE for stochastically spatially configurative strings is solved exactly based on the obtained special initial condition of the SRE for straight strings in a previous paper (J. L. Zhang et al. 2010 Chin. Phys. B 19, 056403).     

Simulations of the flipping images and microparameters of molecular orientations in liquids according to molecule string model

The relaxation dynamics of liquids is one of the fundamental problems in liquid physics, and it is also one of the key issues to understand the glass transition mechanism. It will undoubtedly give enlightenments on understanding and calculating the relaxation dynamics if the molecular orientation flipping images and relevant microparameters of liquids are studied. In this paper, we first give five microparameters to describe the individual molecular string (MS) relaxation based on the dynamical Hamiltonian of the MS model, and then simulate the images of individual MS ensemble, at the same time calculate the parameters of the equilibrium state. The results show that the main molecular orientation flipping image in liquids (including supercooled liquid) is similar to the random walk. In addition, two pairs of the parameters are equal, and one can be ignored compared with the other. This conclusion will effectively reduce the difficulties in calculating the individual MS relaxation based on the single-molecule orientation flipping rate of general Glauber type, and the computer simulation time of interaction MS relaxation. Moreover, the conclusion has no doubt of the reference significance for solving and simulating the multi-state MS model.     

应急物资政企联合储备合作机理研究

针对一些应急物资,采用政府企业联合储备方式储备,可以降低政府储备成本,企业也可以从中获益。本文研究政企联合实物储备的合作机理,分析了联盟参与人之间的博弈关系,建立了联盟收益模型,运用shapley值解决合作的联盟收益分配问题,最后分析了联盟的稳定性。算例分析显示在政企合作联盟中政府和企业关系类似“地主”和“农民”的关系,当企业获得的收益小于其机会成本时,企业不愿意加入联盟,这时政府需对企业进行交叉补贴来维持联盟稳定。缺货成本低于政府储备成本时,政府会考虑与企业联合储备或者选择缺货;缺货成本低于企业储备成本时,政府选择缺货。     

宽带隙半导体CdAl2S4电子结构、弹性和光学性质的研究

采用基于密度泛函理论(DFT)的第一性原理计算方法,对宽带隙半导体CdAl2S4的晶格结构、电学、弹性和光学性能进行了系统的研究. 研究结果表明：CdAl2S4为直接带隙的宽带隙半导体材料;是弹性稳定的具有各向异性的延展性材料;该晶体的光学性质在中能区(3.5 ~12.5 eV)具有较强的各向异性,其强反射峰处于紫外能量区域,因此其可用作紫外光探测或屏蔽材料.     

Zn1-x HfxO的电子结构和光学性质的第一性原理计算

基于第一性原理密度泛函理论,计算分析了Zn1-xHfxO(x=0,0.0312,0.0417,0.0625和0.1250)体系的晶格结构、电子结构,Mulliken电荷布居和光学性质.计算结果表明,随着Hf掺杂摩尔百分比的增大,晶体体积膨胀,费米能级进入导带,其附近的导带部分主要由杂质原子Hf的5d态贡献,Hf-O离子键成分作用凸显,故Hf的掺杂引入施主能级进而形成n型ZnO材料的可能性较大.且通过比较吸收谱、反射谱和折射谱,发现适量掺入Hf原子可使ZnO体系在高能区的透过率增加,能量损失谱出现红移.这些性质均与实验中Hf掺杂有类似结果,由此可知适量掺杂Hf的ZnO体系有望在制备光电子器件等领域发挥作用.     

New smooth gap function for box constrained variational inequalities

A new smooth gap function for the box constrained variational inequality problem(VIP) is proposed based on an integral global optimality condition.The smooth gap function is simple and has some good differentiable properties.The box constrained VIP can be reformulated as a differentiable optimization problem by the proposed smooth gap function.The conditions,under which any stationary point of the optimization problem is the solution to the box constrained VIP,are discussed.A simple frictional contact problem is analyzed to show the applications of the smooth gap function.Finally,the numerical experiments confirm the good theoretical properties of the method.