Correlated electrons in delta-plutonium within a dynamical mean-field picture

Given the practical importance of metallic plutonium, there is considerable interest in understanding its fundamental properties. Plutonium undergoes a 25 per cent increase in volume when transformed from its alpha-phase (which is stable below 400 K) to the delta-phase (stable at around 600 K), an effect that is crucial for issues of long-term storage and disposal. It has long been suspected that this unique property is a consequence of the special location of plutonium in the periodic table, on the border between the light and heavy actinides-here, electron wave-particle duality (or itinerant versus localized behaviour) is important. This situation has resisted previous theoretical treatment. Here we report an electronic structure method, based on dynamical mean-field theory, that enables interpolation between the band-like and atomic-like behaviour of the electron. Our approach enables us to study the phase diagram of plutonium, by providing access to the energetics and one-electron spectra of strongly correlated systems. We explain the origin of the volume expansion between the alpha- and delta-phases, predict the existence of a strong quasiparticle peak near the Fermi level and give a new viewpoint on the physics of plutonium, in which the alpha- and delta-phases are on opposite sides of the interaction-driven localization-delocalization transition.     

Colligative properties of anomalous water

Investigations of the phase behaviour on freezing and subsequent melting and of other properties indicate that anomalous water is a solution containing a fixed amount of relatively involatile material in normal water. There seems to be no need to postulate the existence of a new polymer of water in such solutions. If only water and silica are present, the properties are consistent with those of a silicic acid gel.     

The valence electron structure and properties analysis of TiC

The valence electron structure of TiC was calculated by using the empirical electron theory of solids and molecules. The calculated results show that with the increase of temperature the number of common electrons of TiC increases which indicates that TiC has a good thermal stability; and there exists a close relationship between hardness and brittleness of TiC. According to the number of lattice electrons, the differences among the crystals with different structures can be explained qualitatively. Using the “bond-strengthening factor”, the differences of hardness among the crystals with different structures can also be qualitatively explained to some extent.     

钴高速钢价电子结构与回火性能的研究

计算了含钴高速钢的价电子结构与共价键能 .发现 Co可增强奥氏体和马氏体基体金属原子间结合力 (键参数 nα相应提高 1 2 .5 %～ 30 %和 2 0 %～ 2 7% ) ,有利于更高温度奥氏体化及回火析出量增加 .Co削弱 C与近邻原子的键强与键能 ,提高 C的活度 ,但由于 W- Co,Mo- Co等强键存在 ,因此 Co促进了特殊碳化物的初始析出 ,却阻碍其聚集 ,结果在强化的 α相基体上形成数量更多、弥散程度更高的回火析出 ,提高了其淬火回火状态的室温硬度、高温硬度及红硬性 .     

Electronic origin of the anomalous solid solution hardening of Y and Gd in Mg: A first-principles study

Y and Gd demonstrate anomalous solid solution hardening efficiency,which cannot be understood using the elastic impuritydislocation interaction theory.We performed first-principles calculations to investigate the effect of different alloying elements such as Al,Zn,Y,and Gd on the chemical bonding of Mg solid solutions.The present calculations clearly show that the anomalous solid solution hardening of Y and Gd in Mg may be understood based on the increased bonding strength of both Mg-Y (Gd) and Mg-Mg.     

The origin of the anomalous superconducting properties of MgB(2)

Magnesium diboride differs from ordinary metallic superconductors in several important ways, including the failure of conventional models to predict accurately its unusually high transition temperature, the effects of isotope substitution on the critical transition temperature, and its anomalous specific heat. A detailed examination of the energy associated with the formation of charge-carrying pairs, referred to as the 'superconducting energy gap', should clarify why MgB(2) is different. Some early experimental studies have indicated that MgB(2) has multiple gaps, but past theoretical studies have not explained from first principles the origin of these gaps and their effects. Here we report an ab initio calculation of the superconducting gaps in MgB(2) and their effects on measurable quantities. An important feature is that the electronic states dominated by orbitals in the boron plane couple strongly to specific phonon modes, making pair formation favourable. This explains the high transition temperature, the anomalous structure in the specific heat, and the existence of multiple gaps in this material. Our analysis suggests comparable or higher transition temperatures may result in layered materials based on B, C and N with partially filled planar orbitals.     

价电子层拓扑指数及其对镧系元素理化性质的预测

受Randic分子连接性拓扑指数mX的启发 ,构建了一种价电子层拓扑指数mV。利用其 0阶指数0 V与镧系元素的 14种理化性质关联 ,拟合成 14个线性回归方程。拓扑指数的结构选择性达到唯一性表征 ,预测取得了令人满意的结果     

不规则光栅在双光栅衍射中的作用分析

为了从理论上进一步对双光栅衍射成像状况进行了分析,该文其于双光机衍射成像理论及高斯分布统计理论,对双光栅像面光强分布状况做理论分析,并且分析了当两声光机中的一块发生不规则畸变时,像平面泊光强分布状况,同时也从理论上经出了双光栅衍射成像条件。最后,用计算机模拟和相应实验进行验证。     

《国语》中的一价名词

将现代汉语名词配价的研究应用到古代汉语当中,从亲属称谓名词、属性名词和部件名词三个方面考察《国语》中一价名词的使用情况,发现书中一价名词与其配价名词的关系与一价名词的指称性质有关。表示有指的一价名词,其名元一定要求共现,一般以名元为定语、一价名词为中心语的形式展现,或省略名元,但语境可以帮助补出;当一价名词表示无指时,其名元则为隐性的。     

弧齿锥齿轮波动应力分析

对弧齿锥齿轮推导了计算行波振动应力的方法,采用修改程序的办法使其在通用有限元程序上得以实现。并计算了某型发动机的弧齿锥齿轮的动态应力,讨论了弧齿锥齿轮的重合度ε、模态阻尼比ζ对波动振动应力曲线的影响,最后给出弧齿锥齿轮产生波动振动的条件。     

线性非平衡系统的内变量涨落

推导并给出了线性非平衡系统的内变量涨落的均方差公式，给出了稳定性条件、讨论了相应的均方差、熵平衡方程以及弛豫时间等热力学参量之间的关系。     

超声波对固体颗粒表面性质的影响

研究了在不同频率、功率、时间、温度条件下超声波对固体颗粒大小的影响;探讨了超声波对十六烷基三甲基溴化铵(HDTMA)阳离子表面活性剂在固体颗粒表面解吸性能的影响.结果表明:功率越大、时间越长,超声波作用后固体颗粒粒径均值越小.温度升高,固体颗粒的运动性能增强,超声波作用后粒径均值在55℃时最小,且在频率为40 kHz、功率为50 W、作用时间为50 min及55℃时,颗粒长轴均值从12.575μm减小到7.799μm,短轴均值从6.998μm减小到5.453μm.同时超声波发生器的功率越大、时间越长、温度越高,黏土颗粒表面吸附HDTMA的解吸率增大,且当频率为80 kHz、功率为50 W、时间为50 min、温度为65℃时,其解吸率可达64.69%.     

脉动流速的分解和脉动应力探讨

本文用运动学观点,根据紊流的脉动性质,导出脉动流速的分解方程.此方程将脉动流速分解为三个组成部分,并且据此导出脉动应力分解方程.通过对脉动应力性质的分析,提出一些设想,于是将脉动应力的分解方程简化为三个组成部分,是推广Boussinesq J假设的合理修正和发展,可以用来作为求解紊流问题的基础.     

Stochastic resonance in the growth of a tumor induced by correlated noises

Since half a century ago, nonlinear physics has changed our views of world drastically[1]. People expected to use it to solve the complexity of biology[2,3]. In the past decade, more and more evidence shows that noise plays an impor- tant role in nonlinear systems[4―10], such as noise-induced phase transitions, stochastic resonance (SR) and so on. Especially, SR uncovered a heap of complexities of biol- ogy[11,12]. For many years, the law of tumors growth has been a challenging subject. Sci…     

热混合层中温度脉动的多重分形特性

运用广义计盒维数方法,对测量热混合层所得到的温度脉动时间序列信号进行了详细研究,发现等温截面的时间点集在一定尺度范围内表现出多重分形几何特性,并计算了截面阀值的绝对值范围为０～１．５ 时的等温截面的多重分形的广义计盒维数Ｄｑ,当ｑ ３,Ｄｑ 随截面阀值Ｈ以及测量点位置Ｙ的变化不大,热混合层温度脉动时间序列具有统一的多重分形维数;但当ｑ ＞ ３,Ｄｑ 受湍流流场本身的影响很大．     

Fluctuating superconductivity in organic molecular metals close to the Mott transition

On cooling through the transition temperature T(c) of a conventional superconductor, an energy gap develops as the normal-state charge carriers form Cooper pairs; these pairs form a phase-coherent condensate that exhibits the well-known signatures of superconductivity: zero resistivity and the expulsion of magnetic flux (the Meissner effect). However, in many unconventional superconductors, the formation of the energy gap is not coincident with the formation of the phase-coherent superfluid. Instead, at temperatures above the critical temperature a range of unusual properties, collectively known as 'pseudogap phenomena', are observed. Here we argue that a key pseudogap phenomenon-fluctuating superconductivity occurring substantially above the transition temperature-could be induced by the proximity of a Mott-insulating state. The Mott-insulating state in the kappa-(BEDT-TTF)2X organic molecular metals can be tuned, without doping, through superconductivity into a normal metallic state as a function of the parameter t/U, where t is the tight-binding transfer integral characterizing the metallic bandwidth and U is the on-site Coulomb repulsion. By exploiting a particularly sensitive probe of superconducting fluctuations, the vortex-Nernst effect, we find that a fluctuating regime develops as t/U decreases and the role of Coulomb correlations increases.     

LiSiPON固态薄膜电解质的结构和性能分析

以Li3PO4和Si3N4为靶材,利用离子束辅助沉积N离子流轰击法制备非晶结构的固态电解质LiSiPON薄膜.实验中,通过控制N2气和Ar气的流量比,调节薄膜的含氮量.利用X线衍射、X线能量色散谱仪和X线光电子能谱仪研究薄膜的结构和组织成分的变化,并通过电化学阻抗测试仪获得薄膜的离子电导率,研究不同氮氩比对LiSiPON薄膜结构、组成和电学性质的影响.结果表明:N2和Ar流量比为1∶1时,薄膜含氮量最高,离子电导率达到最大值,在室温时电解质薄膜的离子电导可达6.8×10-6S/cm,是一种有潜力应用于全固态薄膜锂离子电池的电解质材料.     

河南省粮食产量周期波动分析

利用1951--2005年河南省粮食产量统计数据,应用波动理论和周期理论分析河南省粮食产量波动规律,考察河南省粮食产量波动的历史过程和数量特征．结果表明,河南省粮食产量波动具有短周期的显著特征,平均波动周期3.3年左右,波幅较小,扩张期略长于收缩期．     

3个实验小鼠品系下颌骨变量波动性不对称

了解不同实验小鼠下颌骨变量波动性不对称性(FA)特征.对3个实验小鼠品系的下颌骨11个变量进行测量.3个小鼠品系是KM 58例(♂31,♀27),ICR 20例(♂10,♀10)和BALB/c 20例(♂10,♀10).采用SPSS13.0统计软件进行数据分析,Kolmogorov-Smirnov用来检验FA值的正态分布,参数检验ANOVA和非参数统计检验Mann-Whitney用来检验FA值在性别之间和品系之间差异.结果表明不同品系之间FA值变化有一定差异;3个品系中有一个品系的FA值存在性差.3个品系之间FA值出现差异主要原因是出生后环境的影响,遗传因素影响较小.     

脉动压力环境成因及其定性特征

立足于工程设计中结构稳定性分析的需要,分别从物理流动现象和流动稳定性理论及湍流理论出发,分析了脉动压力环境的成因及特征。在综合比较了研究脉动压力环境的几种方法之后,指出数值模拟技术与脉动压力的工程预测模型相结合的研究方案具有很好的应用前景和经济价值。