On the lattice Boltzmann method for phonon transport

The lattice Boltzmann method is a discrete representation of the Boltzmann transport equation that has been employed for modeling transport of particles of different nature. In the present work, we describe the lattice Boltzmann methodology and implementation techniques for the phonon transport modeling in crystalline materials. We show that some phonon physical properties, e.g., mean free path and group velocity, should be corrected to their effective values for one- and two-dimensional simulations, if one uses the isotropic approximation. We find that use of the D2Q9 lattice for phonon transport leads to erroneous results in transient ballistic simulations, and the D2Q7 lattice should be employed for two-dimensional simulations. Furthermore, we show that at the ballistic regime, the effect of direction discretization becomes apparent in two dimensions, regardless of the lattice used. Numerical methodology, lattice structure, and implementation of initial and different boundary conditions for the D2Q7 lattice are discussed in detail.     

Dual Reciprocity Boundary Element Method for Magnetohydrodynamic Flow Using Radial Basis Functions

A dual reciprocity boundary element method is given to obtain the solution in terms of velocity and induced magnetic field for the study of MHD (magnetohydrodynamic) flow through a rectangular duct having insulating walls. The equations are transformed to two types of nonlinear Poisson equations and the right-hand sides in these equations are approximated using combinations of two classes of radial basis functions (the value of the function and its normal derivatives are utilized for approximation). Computations are carried out for several values of the Hartman number (0 h M h 10) by using constant boundary elements. Comparisons are made for two types of formulations and for traditional and osculatory type approximations of the right-hand side functions. It is found that osculatory interpolation gives better results than traditional interpolation and the type of the Poisson equation, which contains derivative of the unknown function, is better than the other type, which contains unknown function only. The results for velocity and induced magnetic field are illustrated by some selected graphs.     

Study of the field emitted by a source placed inside a two-dimensional left-handed metamaterial

We studied the properties of electromagnetic waves that were emitted from a source placed inside a left-handed medium based on a two-dimensional labyrinth. While the arguments of geometrical optics suggest that the field emitted from the source would be focused outside the left-handed medium no matter where the source was placed, our results proved the contrary. We found that the field emitted from the source was focused outside the left-handed medium when the source was placed inside the medium at a certain distance away from the interface. Moreover, our results showed that the field emitted from the source was focused on the subwavelength dimensions outside the left-handed medium.     

基于电磁振动上料的茶梗和昆虫异物近红外光谱和荧光图像在线检测研究

茶叶是大众青睐的健康饮品之一,但茶叶在机器采收和加工过程中,容易混入茶梗和昆虫异物,污染茶叶、影响其质量安全,是未来应防范和检测的重点。X射线成像技术,根据食品基质和异物的密度差实施检测,广泛适用于金属异物并延伸至高密度塑料,但对于茶梗、昆虫这类低密度有机异物尚不适用,所以迫切需要研发新型无损检测技术和方法。针对片状茶叶重叠、遮掩异物的问题,提出了电磁振动上料辅助近红外光谱和荧光图像的检测方案,进行绿茶中的内源性异物茶梗和外源性异物昆虫的在线检测研究。通过电磁振动上料辅助近红外光谱和荧光成像系统,采集了600～1 050 nm范围的近红外光谱600条和RGB-N四通道图像各65幅。采用451条光谱进行建模,其余149条光谱作为预测集,评估模型的性能,比较了去趋势(Detrending)、多元散射校正(MSC)、标准正态变换(SNV)、变权重正态变换(VSN)、迭代自适应加权惩罚最小二乘法(airPLS)、不对称最小二乘法(ALS)、光程估计与校正(OPLEC)等不同光谱预处理方法的处理效果,其中OPLEC能较好地消除散射效应,偏最小二乘判别分析(PLS-DA)模型的正确识别率由78%提...     

Synthesis of N‐Alkylated Indolines and Indoles from Indoline and Aliphatic Ketones

A survey of redox aminations of indoline with aliphatic ketones using bismuth nitrate as catalyst is described. A reaction of an equivalent amount of indoline and aliphatic cyclic and acyclic ketones provides a mixture of excessive alkylated indole derivatives over typically redox isomerization and reductive alkylation pathways while using of the five equivalent of indoline provides N‐alkylated indolines as a reductive alkylation product. The desired N‐alkyl indoles from the oxidation of N‐alkyl indolines were obtained in excellent yields.     

Redox Amination Scope of Benzylic Ketones with Indoline: Synthetic and Mechanistic Insights

Bi(NO₃)₃·5H₂O‐Catalyzed redox amination scope and mechanistic insights of benzylic ketones with indoline are discussed. The experimental results demonstrate that the formation of N‐alkyl‐substituted indole/indoline derivatives over typically competitive redox and reductive amination processes is depending upon the reaction condition for the benzylic ketones.     

On some constacyclic codes over $$\mathbb {Z}_{4}\left[ u\right] /\left\langle u^{2}-1\right\rangle $$, their $$\mathbb {Z}_4$$Z4 images,and new codes

In this paper, we study \(\lambda \)-constacyclic codes over the ring \(R=\mathbb {Z}_4+u\mathbb {Z}_4\) where \(u^{2}=1\), for \(\lambda =3+2u\) and \(2+3u\). Two new Gray maps from R to \(\mathbb {Z}_4^{3}\) are defined with the goal of obtaining new linear codes over \(\mathbb {Z}_4\). The Gray images of \(\lambda \)-constacyclic codes over R are determined. We then conducted a computer search and obtained many \(\lambda \)-constacyclic codes over R whose \(\mathbb {Z}_4\)-images have better parameters than currently best-known linear codes over \(\mathbb {Z}_4\).     

Convergence of Solutions of Nonhomogeneous Linear Difference Systems with Delays

Sufficient conditions are given for the asymptotic constancy of the solutions of a linear system of difference equations with delays. Moreover, it is shown that the limits of the solutions, as t→∞, can be computed in terms of the initial function and a special matrix solution of the corresponding adjoint equation.