S2Cl2异构体最大硬度原理的密度泛函理论研究

在LDA／NL水平研究了最大硬度原理(MHP)在S2C12分子旋转异构化过程中的真实性。报告了S2C12分子在键的旋转异构化过程形成的各种异构体分子的硬度、化学势和总能量的计算值，并由此得出重要结论：①在分子旋转异构化过程中，硬度最大的分子能量最小，而硬度最小的分子能量最大，用计算的硬度表征S2Cl2异构体的稳定性与计算的总能量表征S2C12异构体的稳定性相当吻合，从而使最大硬度原理被进一步证实。②虽然化学势不宜表征异构体的稳定性，但是恒定的化学势是最大硬度原理成立的重要条件。     

H6M4(N2H2)3(M=Al,Ga)簇合物的结构、红外光谱和热力学性质研究

采用自洽场方法(HF)和密度泛函(DFT)的B3LYP方法，在6-31G^*水平下，研究了H6M4(N2H2)3(a—M＝Al，b—M＝Ga)簇合物的几何构型、电子结构、红外光谱及热力学性质．结果表明：N—N键比肼中N—N键长，有进一步裂解的趋势．振动频率计算表明：铝、镓的肼簇合物为基态稳定结构．     

辣椒高产优质栽培技术研究进展

立足于肥料、植物生长调节剂、种植密度、保护地设施和EM5个方面的研究,分别论述了各技术对辣椒高产优质的影响,并就辣椒栽培中存在的一些问题进行了探讨。     

The age of formation of the mirabilite and sand wedges in the Hexi Corridor and their paleoclimatic interpretation

The Hexi Corridor is located at the transition zone of the Asian summer monsoon and westerly airflow, and lies in an important position in terms of its ecological fragility and climatic sensitivity. During a recent field expedition to this region, we found a sedimentary mirabilite layer in a number of localities including Suwushan, Yanchi, Baitujing, Yanchi Gaotai, Huahai, Yumen, Halanuo扙r, and Dunhuang (Fig. 1), which have the potential to provide important information about environmenta…     

Contributions of different land cover types in Otindag Sandy Land and Bashang area of Hebei Province to the material source of sand stormy weather in Beijing

Different land cover types in Otindag Sandy Land and Bashang area of Hebei Province are linked to a material source of sand stormy weather in Beijing based on results of field vegetation and soil survey and laboratory works. Results of grain size analysis show that dust release potential in per unit area of moving sandy land is small,while lowland meadow and meadow steppe in stony hills have high potential of releasing dusts in per unit area during sand stormy weather occurrence. Further considering the effects of vegetation, it is inferred that the moving sandy land served as a material source of past dust storm and the possibility of dust release in per unit area is low in current time.Typical steppe in stony hills is undergoing desertification and its dust release possibility in per unit area is high. Farmland has strong potential of release dusts when they are ploughed in spring, but a large amount of therophytes grow and thus prevent dusts from release when cultivation was terminated.Potentials of dust release in per unit area in fixed sand dunes,stony mountain meadow steppe and low land meadow are lowdue to high cover of perennials. Sand dune reactivation and desiccation of lakes and lowlands under estimated future climatic change will make them serve as a future material source of sand stormy weather.     

一类理想二次损失函数下多参数统计模型的风险估计

Bunke曾讨论了一类多参数控制的线性模型在带正定“加权”矩阵的二次损失函数下，最佳线性无偏估计量的极小极大性。然而，对于相应风险中具有大估计温差的不合理加权，上述损失函数巳不适用。为此，提出了一类更为理想的二次损失函数，并在此损失函数下，对相关风险进行了极小极大估计与比较．结果表明，所提出的二次损失函数是合理的、适用的．     

A14（iPrNNiPr）3簇合物的理论研究

用HF／6—31G^*和B3LYP／6—31G^*方法，首次研究了A14(iPrNNiPr)。簇合物的几何构型、电子结构；并在B3LYP／6—31G^*水平下，对所得平衡构型进行了红外光谱及热力学性质计算。结果表明：在此簇合物中Al—N键比氮化铝簇中Al—N键长，但仍在极性共价键的范围内；N—N键都较肼中N—N键明显减弱，易断裂，可释放较多能量，因此它作为生成相应氮化物的前体，将降低反应所需活化能。振动频率计算表明：该簇合物为基态稳定结构。     

高温平板滞止区内饱和水喷流沸腾传热最大热流密度

对高温平板滞止区内饱和水喷流冲击沸腾的临界热流密度进行了理论解析和实验研究。根据气液两相流稳定性理论得到了气泡层下最大液膜底层厚度，并由最大液膜底层厚度和液膜平均流速，建立了一个预示临界热流密度的半理论方程。方程系数由稳态实验数据拟合得到。研究结果证明，临界热流密度取决于滞止冲击速度和喷流直径，半理论半经验式能较好地预示实验结果。     

两类熵密度规划的对偶规划和最优性条件

基于广义的Fenchel对偶定理及其相应的Kuhn-Tucker条件，给出了带有二次约束和熵密度约束的二次规划问题和熵密度问题的对偶规划，强对偶定理以及Kuhn-Tucker条件。     

基于 PDM控制的高频交流交交变换器的建模

根据软开关谐振理论,对三相高频交流交交变换器,提出了一种新颖的脉冲密度调制(PDM)的控制策略,并采用PDM控制策略建立了变换器的数学模型和仿真模型,分析了变换器输出波形。研究表明,在高频输入信号条件下,PDM控制技术可以将高频输入电压合成为幅值和频率变化的低频信号,具有操作简单、控制方便的特点。