The heat capacity of small metallic grains studied by the random matrices theory

The random matrices theory is applied to a study of the heat capacity of small metallic grains. The numerical calculations indicate that the level distribution and the difference between the particles respectively with an even and an odd numbers of electrons are important for the heat capacity of the small metallic grains at a low temperature and the level correlation mainly affects the heat capacity at a high temperature.     

立方面心C60晶体晶格振动的研究

采用C60分子之间相互作用势的Kihra形式,研究了立方面心C60晶体的晶格振动问题,得到了质心振动沿[111]、[110]及[100]方向的声子散射圆频率分布曲线及C60晶格振动频率的态密度分布.采用所得到的C60晶格振动频率的态密度分布,计算了晶体C60在298 K时的等压热容,所得数值与实验值相符.     

重庆轻轨较新线无线通信系统设计探讨

针对重庆特殊的地理环境 ,着重讨论重庆轻轨较新线无线通信系统应具备的功能和构成特点 ,对基站加光纤射频直放站系统模式 ,优化设计和节省投资方面进行了探讨     

Strong Universal Pointwise Consistency of Recursive Regression Estimates

For semi-recursive and recursive kernel estimates of a regression of Y on X (d-dimensional random vector X, integrable real random variable Y), introduced by Devroye and Wagner and by Révész, respectively, strong universal pointwise consistency is shown, i.e. strong consistency P _X -almost everywhere for general distribution of (X, Y). Similar results are shown for the corresponding partitioning estimates.     

图的边覆盖染色中的分类问题(英文)

设 G是一个图 ,其边集是 E( G) ,E( G)的一个子集 S称为 G的一个边覆盖 ,若 G的每一点都是 S中一条边的端点 .G的一个 (正常 )边覆盖染色是对 G的边进行染色 ,使得每一色组都是 G的一个边覆盖 ,使 G有 (正常 )边覆盖染色所需最多颜色数 ,称为 G的边覆盖色数 ,用χ′c( G)表示 .已知的结果是对于任意简单图 G,都有 δ- 1≤ χ′c( G)≤ δ,δ是 G的最小度 .若 χ′c( G) =δ,则称 G是 CI类的 ;否则称为 CII类的 .本文主要研究了平面图及平衡的完全 r分图的分类问题     

Experimental Evaluation of Procedures for Heat Capacity Measurement by Differential Scanning Calorimetry

Experimental evaluation of the procedures adopted for heat capacity measurements employing differential scanning calorimetry (DSC) has been carried out by taking nickel and sapphire as test samples. Among the various methodologies reported in literature, the absolute dual step method was chosen for this purpose due to its simplicity and minimum number of measurements required. By proper temperature and heat flux calibration employing indium as reference, it was possible to obtain the calibration factor independent of temperature. This was ascertained by analysing other pure metals namely Sn, Zn, Cd, and Pb and determining their melting temperatures and heats of melting. Various operator- and sample-dependent parameters such as heating rate, sample mass, the structure of the sample, reproducibility and repeatability in the measurements were investigated. Heat capacities of both nickel and sapphire have been determined using the above method. Further, the heat capacity of nickel has also been determined using the widely employed three-step method taking sapphire as the heat flux calibration standard. Both methods yielded the comparable heat capacity values for nickel. Based on the parameters investigated and their influence, it could be concluded that reasonably precise and accurate heat capacity measurements are possible with DSC. One advantage of this method is the elimination of a separate calibration run using a reference material of known heat capacity. This revised version was published online in August 2006 with corrections to the Cover Date.     

Heat Capacities of Hydroxy and Aminoderivatives of Benzene

Heat capacities in the liquid phase C ^l of methylbenzeneamines and heat capacities in the solid phase C ^s of benzenediols and of 4-methylbenzeneamine were measured by commercial Setaram heat conduction and power compensated calorimeters. Results obtained cover the following temperature range (depending on the compound and state of aggregation): 2-methylbenzeneamine 313 to 371 K, 3-methylbenzeneamine 263 to 371 K, 4-methylbenzeneamine 133 to 353 K, 1,2-benzenediol 153 to 353 K, 1,3-benzenediol 173 to 353 K, 1,4-benzenediol 133 to 403 K. The heat capacity data obtained in this work were merged with experimental data from literature, critically assessed and sets of recommended data were developed by correlating selected data as a function of temperature. This revised version was published online in August 2006 with corrections to the Cover Date.     

Relationship Between Heat Capacity and Thermal Expansion Derived from the Lennard–Jones Potential

The relationship between heat capacity (C _p) and linear thermal expansion (α) derived from the Lennard–Jones potential is C _p=Aα(U ₀–E), where U ₀ is the heat of sublimation at T=0, E is the enthalpy and A is the coefficient. The values of A for different solidified inert gases coincide with one another within the limits of experimental error (±2%). The relationship is shown to be valid for various substances: solidified rare gases, diamond, halite and copper. This revised version was published online in July 2006 with corrections to the Cover Date.     

Study of the electrosynthesis of poly(3-butylthiophene) and its semiconductor properties

The mechanism of the electrosynthesis of poly(3-butylthiophene) (PBuT) was studied by cyclic voltammetry and potential step methods in comparison with polybithienyl. The anodic oxidation polymerization of the 3-butylthiophene underwent two steps: oligomer formation and further polymerization to form the polymer. The doping level of the PBuT increases with the cycle number of the potential sweeps during polymerization. The current responses to the potential steps indicate a nucleation and nuclei growth process which is repeated layer to layer. The differential capacity (C _d) and photocurrent were measured at the PBuT films in the aqueous electrolyte solution. The C _d ⁻² vs. E plot shows two regions of linearity, one with a negative slope and the other with a positive slope in different potential regions, which give the same flat-band potential. This indicates that the PBuT film exhibits both p-type and n-type features of a semiconductor at differrent potential regions. The cathodic photocurrent spectrum was analysed by the (j _ph hν)^{2/ n} vs. hν plots, giving band gap energies of 2.41 eV for n=1 and and 2.01 eV for n=4. Received: 29 July 1999 / Accepted: 15 November 1999     

Deformation processes below a plate sinkage test on sandy loam soil: theoretical approach

Mathematical models to predict the mode and extent of deformation occurring below sinkage plates are presented in the first part of this paper which encompasses the theoretical approach to the subject. These models are based on previous work by Earl (Earl R. Assessment of the behaviour of field soils during compression. Journal of Agricultural Engineering Research 1997;68:147–57)who developed a procedure to predict the likely mode of deformation using confined compression tests carried out alongside plate sinkage tests. This work suggested that soil behaviour, during increasing compression under a sinkage plate, is governed by three processes; (i) compaction below the plate with constant lateral stress, (ii) compaction with increasing lateral stress, and (iii) displacement and compaction of soil laterally. The aim of this second part to the paper is to observe soil deformation processes occurring below a circular sinkage plate to examine (i) whether the three phases of deformation referred to above occur in practice, and (ii) the accuracy of the models for predicting the soil deformation processes that occur. Tests were carried out on sandy loam soil under controlled conditions in a soil bin. Observations of deformation processes, recorded using long-exposure photography, revealed that during the initial stages of sinkage (a few millimetres), the corresponding disturbance of soil below the plate extended disproportionately further and was cylindrical in form. As sinkage progressed, the deformation process went through a transitional stage before reaching the more widely recognised form of the development of an inverted cone of compacted soil directly below the plate which moved with the plate causing lateral soil movement and compaction. Predictions for a medium density sandy loam were found to be in broad agreement with soil behaviour under a semi-circular sinkage plate observed behind a sheet of tempered glass under controlled conditions in a soil tank.