Toward a microscopic analysis of the marginal fermi liquid

We analyze the electron-boson interaction using many-body methods in the framework of the marginal Fermi liquid theory. Special attention is paid to the approximations necessary to obtain a marginal behavior. We show that the effective coupling constant between electrons is attractive on the entire energy scale. The renormalization of the bosonic spectrum due to the Coulomb interaction is also analyzed.     

Marginal fermi liquid behavior for a two-dimensional electronic system

The imaginary part of the self-energy of a two-dimensional Fermi system interacting with bosonic excitations has been calculated analytically and numerically. The result shows a marginal Fermi liquid behavior. The model can be a reasonable approach for studying the marginal behavior of a two-dimensional Millis-Monien-Pines phenomenological model.     

广义Ginzburg-Landau方程的格子Boltzmann模型

本文为了求解广义Ginzburg-Landau方程,提出了带有附加项的五点单弛豫格子Boltzmann模型.首先通过使用Chapman-Enskog展开和Taylor展开,得到了一系列不同时间尺度的偏微分方程和平衡态分布函数的高阶矩.然后我们利用平衡态分布函数的矩方程构造了具有截断误差的格子Boltzmann模型,得到了数值耗散项,并应用Hirt启示性稳定化方法得到模型的稳定条件.最后,我们给出了广义Ginzburg-Landau方程的数值例子.数值结果表明这种方法可以用来模拟广义Ginzburg-Landau方程.     

相关函数算法在超声导波计量管道内液体流速中的应用

通过对超声导波技术在充液管道内流量计量的研究,提出了一种新的供热管路中热量表流量计量在线检测方法。试验中,因超声导波在充液管道内传播速度较快,为了准确地测量管道内液体流速对导波传播速度的影响,需要非常准确地提取导波的传播时间。分析了相关函数法在计算导波传播时间的应用原理,并通过理论分析和实验验证了相关函数法的准确性,为采用超声导波测量管道内液体流量提供理论基础。     

Traveling wave solution of heat transfer for small sample moving in the sub-cooled liquid nitrogen

The temperature field of a traveling wave in a system is analyzed. The system consists of a rapidly moving small specimen tube and sub-cooled liquid nitrogen (SLN₂). The temporal and spatial temperature distribution of the subsonic wave is investigated. The relationship between a dimensionless cooling rate and the thermal Mach number (M) is derived. When the quenching speed of sample tube in the sub-cooled liquid nitrogen is equal to or faster than that of the thermal wave propagated, a shock wave is expected.     

Analytical model for the Fermi energy and the work function of thin metallic films

An analytical theory of size-dependent energetic characteristics of a metal film is developed in a free-electron model and a finite square potential well. A regular expansion of energetic characteristics in terms of 1/L is performed. The errors occurring at each step of the expansion are analyzed. This simple model allows to calculate size oscillations of the Fermi energy and the work function.     

Singularity analysis, balance equations and soliton solution of the nonlocal complex Ginzburg-Landau equation

The modified complex Ginzburg-Landau equation (mCGLE) which includes a delayed response term in the integral form is analysed. In particular, a singularity analysis of mCGLE is presented. It is shown that this equation fails to pass the Painlevé test when the non-conservative terms are nonzero. Nevertheless, exact solutions to this equation do exist. Stationary solutions can be treated using the segment balance method which is an extension of conservation laws to non-conservative systems. This method is used to derive an exact soliton solution of mCGLE.     

Magnetic correlations and disorder in a two-dimensional fermi liquid: Possible important effects for high-Tc superconductors

The influence of magnetic correlations and disorder in a two-dimensional Fermi liquid is considered in connection with the occurrence of the superconducting state. The disorder effect and magnetic correlations work against the superconducting state but at the same time are competitive phenomena. We show that the critical temperature can decrease due to the magnetic correlations and disorder, but the effect of correlations is reduced by the disorder. The electronic mass enhancement has been calculated taking into consideration the magnetic correlation effects and disorder. Its dependence on the concentration impurities, in agreement with the experimental data, shows the importance of the localization effects due to disorder. These results are in agreement with the experimental data obtained for the high critical temperature superconductors.     

一类弱非线性波浪数值模型及其适用性分析

研究了一类含弱非线性的改进型Boussinesq水波方程,在非交错网格下,利用有限差分法建立了混合四阶Adams-Bashforth-Moulton的预报校正格式的波浪数值模型。在数值模型中,关于空间一阶导数差分格式采用四阶精度、二阶导数差分格式采用二阶精度。针对波浪的一维、二维传播变形问题进行了数值计算,并通过与相关实验结果对比分析考察了该数值模型的适用性。     

金属Cu液态结构的纳米晶粒模型

为研究液态Cu的短程有序结构,建立了液态微观结构的纳米晶粒模型,从晶体X射线衍射学的角度出发,通过对固态Cu衍射峰的宽化计算出了液态X射线衍射强度曲线.计算出的强度曲线与实验获得的液态Cu的X射线衍射强度曲线具有较好的一致性,这证明纳米晶粒模型的正确性,同时也证明了Cu的液态短程有序结构与其固态晶体结构存在着密切相关性,即Cu的液态短程序结构为fcc.     

Deriving the dynamic stress function using complex function and its application to the analysis of the stress distribution around an elliptical hole

In the engineering field, analyzing the stress distribution of an elastic body to which an impact force is applied at its boundary is one of the most interesting problems. However, owing to the absence of a useful and easy method of analyzing the stress distribution of an arbitrarily shaped body, it is difficult to grasp the strength of an elastic body. Therefore, we first devise an easy and useful method employing the complex stress function and then analyze the stress distribution of a body that has an elliptical hole.     

低温液体储箱加压排液过程计算模型比较

低温液体储箱加压排液过程是一个复杂的传热传质过程,很难得到十分精确的模拟计算数据。针对定流量增压系统,提出了整体模型和分层模型及模拟计算过程,并分析比较两者的计算结果,都与物理现象及相关文献吻合。这两种模型为定流量加压排液过程提供了研究方法,其中,整体模型的计算结果较为保守,而分层模型的计算结果更接近实际,更经济可靠。     

Quantum Hall effect in the field-induced spin density wave states

The Hall conductance is investigated in the field-induced spin density wave phases of the quasi-one-dimensional system. The role of the order parameters in the quantization of the Hall effect is shown in the framework of the topological number of the wave functions in the momentum space. A possible mechanism of the sign changes of the Hall conductance observed in the experiments is proposed in this framework.     

水中桥塔波浪作用动力模型试验相似方法与模型设计方法

针对跨海桥梁桥塔结构波浪作用动力模型试验研究方法,通过分析水中结构动力模型试验相似原理,提出了桥塔结构动力模型试验的相似方法与模型设计方法.基于此,设计制作了一大型跨海斜拉桥桥塔结构的动力模型,并利用该试验模型进行了结构动力特性试验和波浪作用动力响应试验.动力特性试验结果表明:试验测得的结构主要自振频率与原型结构设计自...     

连续波金属探测器电磁场模型的理论分析

介绍了连续波金属探测器的工作原理，提出一种新的连续波金属探测器电磁场模型，采用基于电磁场和电路的混合方法对该模型进行了详细的理论分析，推导出在空气及海水中金属探测器接收感应电压的计算公式，并给出了简要的设计实例．文中理论分析结果对于连续波金属探测器设计与分析具有指导意义，对其它类型的金属探测器设计也有参考价值．     

坑道口部Ｂ炸药爆炸冲击波传播速度模型试验研究

准确计算口部内爆炸条件下坑道中冲击波传播速度的变化规律,是坑道工程中防护设施抗精确打击设计的前提。为此,在野外进行１０次模型坑道内爆炸试验。模型坑道由可拼装式钢结构单元组成,净截面积为６０ｃｍ×６０ｃｍ,Ｂ炸药装药量范围为７５ｇ～５００ｇ。通过安装于坑道侧壁上的压力传感器实测冲击波波形,由实测数据拟合出坑道口部内爆炸条件下冲击波沿等截面直坑道传播的速度模型。算例分析表明,所拟合的坑道内冲击波传播速度的工程经验模型具有较高实用价值。     

风浪谱模型在高度计风速反演中的应用

依据粗糙海面电磁波镜面散射理论,将根据全波数范围内的风浪谱模型计算的标准化雷达后向散射截面与T/P卫星高度计测得的雷达后向散射截面(Ku波段)进行比较,实现了对高度计风速的反演.研究表明,在所选浮标附近海域,波龄因子对高度计风速反演存在较大影响.与目前高度计业务化算法相比,考虑波龄因子影响后,根据谱模型反演获得的风速与中国近海浮标风速之间均方根误差和平均偏差更小.由于波龄因子可以根据高度计测得有效波高以及业务化算法获得的风速得到,因此根据风浪谱模型反演获得的风速具有广泛的适用性.     

埋置块式基础地基阻抗函数的简化计算方法研究

目前关于地基阻抗的分析和计算方法都比较繁琐,不易为工程设计人员所掌握.基于此,提出了埋置基础地基阻抗函数的简化计算方法.首先,采用锥体模型分析均质半空间内埋置圆盘一维振动波的传播过程,得到了平动和转动时的地基阻抗.在此基础上,利用埋置圆盘组来模拟埋置基础,分析得到了埋置基础地基阻抗函数.最后,通过算例表明此方法计算效率高,误差小,适用于工程计算.     

Development of typhoon driven wave nowcasting model in Southeast China Sea

Using Optimal Interpolation data assimilation of observed wave spectrum around Northeast coast of Taiwan Island, the typhoon driven wave nowcasting model in Southeast China Sea is setup. The SWAN model is used to calculate wave field and the input wind field is the QSCAT/NCEP data. The two-dimensional wavelet transform is applied to analyze the X-band radar image of nearshore wave field and it reveals that the observed wave spectrum has shoaling characteristics in frequency domain. The reverse calculation approach of wave spectrum in deep water is proposed and validated with experimental tests. The two-dimensional digital low-pass filter is used to obtain the initialization wave field. Wave data during Typhoon Sinlaku is used to calibrate the data assimilation parameters and test the reverse calculation approach. Data assimilation corrects significant wave height and low frequency spectra energy evidently at Beishuang station on Fujian Province coast, where the entire assimilation indexes are positive in verification moments. The nowcasting wave field shows that the present model can obtain more accurate wave predictions for coastal and ocean engineering in Southeast China Sea.     

液浸多层薄膜-基底结构中Scholte界面波特性研究

多层薄膜-基底结构在工业领域有广泛应用，其中薄膜的厚度与弹性参数等特性对结构与器件性能有显著影响。但对多层薄膜材料参数进行无损定征较为困难。考虑界面波对界面附近材料特性敏感的特点，以及分层薄膜导致液固界面Scholte波频散与分层材料速度分布密切相关等因素，文章首先利用全局矩阵理论分析了分层结构中的声传播，并给出界面上脉冲激励的声压表达式，据此对水浸双层薄膜-基底三层结构材料声速呈正梯度、负梯度、随机分布三种结构中液固界面Scholte波的频散曲线进行数值计算。进一步详细计算了法向脉冲线源激发的界面波瞬态信号随薄膜厚度的变化。结果显示，三种结构中两层薄膜厚度均对液-固界面波频散特性有显著影响，同时不同膜厚对不同频段的Scholte波的“捕获”作用(频率选择性)十分明显。该结果为进一步利用Scholte波频散特性进行多层薄膜厚度定征提供了理论依据。