Ultrasound-promoted greener approach to synthesize α-hydroxy phosphonates catalyzed by potassium dihydrogen phosphate under solvent-free condition

We report a new environmentally-benign, convenient, and facile methodology for the synthesis of α-hydroxyphosphonates from an aromatic/heteroaromatic aldehyde with triethyl phosphite in the presence of potassium dihydrogen phosphate (KH₂PO₄) under ultrasound-assisted solvent-free conditions. Furthermore, a series of compounds were synthesized and characterized by melting point, EI-MS, NMR, and IR tools. Utilization of easy reaction conditions, isolation, and purification makes this manipulation very interesting from an economic perspective.     

临界Galton-Watson过程条件极限定理的构造性证明

对临界Galton-Watson 过程,本文通过精细地构造条件Galton-Watson 树的方法, 在第n代不灭绝的条件下研究第nt代粒子数Z_nt的构造性性质(0nt^l和Z_nt^r.本文分别给出了{Z_nt^l/n│Z_n>0 }和{Z_nt^r/n│Z_n>0} 的条件极限性质,用概率的方法部分地解释了Spitzer, Lamperti和Ney的经典条件极限的结果. 最后还给出了最近共同祖先的条件分布.     

The virtual element method for a nonhomogeneous double obstacle problem of Kirchhoff plate

This paper is intended to propose and analyze the lowest order conforming and nonconforming virtual element methods (VEMs) for a nonhomogeneous double obstacle problem in fourth-order variational inequality. We first present an abstract framework for the error analysis of an abstract discrete method. Then, we develop the conforming and fully nonconforming VEMs for the previous problem, with the optimal error estimates obtained by using the previous abstract framework combined with two modified interpolation operators and the related estimates. The discrete problem is solved by the primal–dual active set algorithm and the numerical results are in good agreement with theoretical findings.     

A note on the quasi-periodic solutions of the modified Boussinesq hierarchy

Based on the theory of trigonal curve and the properties of three kinds of the Abel differentials on it, we deduce the explicit theta function representations of the Baker-Akhiezer function and the meromorphic function associated with the modified Boussinesq hierarchy. The modified Boussinesq flows are straightened using the Abel map and the Lagrange interpolation formula. The explicit theta function representations of solutions for the entire modified Boussinesq hierarchy are constructed with the aid of the asymptotic properties and the algebro-geometric characters of the meromorphic function.     

带约束条件的停车场启发式停车诱导算法

随着城市化进程的推进,市区停车难严重制约交通的发展。针对停车场使用效率低下问题,分析了影响车位选择的各种因素,提出带有约束条件的泊车诱导算法,通过划分场内小区保证车辆在空间均衡分布,以最短行驶路径/时间和停车难度两项指标衡量道路权重,使用改进的启发式A*搜索算法计算最佳车位。仿真结果证明方法合理可行,在时间和效率上有所节省,所选的最佳车位更符合实际情况。     

基于Euler算法的全向轮机器人位姿检测

现代机器人多借助于参照物定位,多受制于参照物。对于此问题,这里介绍了一种基于码盘和Euler算法定位的无参照物的全向轮机器人设计。利用120度分布的三个全向轮的结构优势,设计了一款能实现在二维平面内移动定位的机器人。此机器人通过采集2个相对编码器和一个绝对编码器数据来获取机器人位姿信息,并接收上位机发送的坐标指令和用Euler算法计算机器人运动坐标,然后将机器人位姿信息与计算出来的坐标相比较,对机器人进行姿态矫正,最终达到追踪有效给定坐标的目的。     

凝聚态硝基甲烷分解机理的密度泛函研究

用密度泛函理论在B3LYP/6-311++G（2d,2P）计算水平上对最低单态和最低三态的硝基甲烷分子进行了分子动力学计算分析,发现,硝基甲烷分子基态沿C-N键分解生成硝基和甲基反应通道上不存在过渡态,只能是在能量足够高的时候造成C-N键的断裂,键离解能为53.4kcal/mol;硝基甲烷分子在最低三态沿C-N键分解生成硝基和甲基的反应通道上,有一个活化能为87.8kcal/mol的能垒。计算得到硝基甲烷分子从基态到最低三态份分解反应发生所需要的总能量为144.58kcal/mol.这个数值与硝基甲烷材料的电子碰撞实验在193nm处的有强吸收峰的结论相符合。依据多声子迁移理论,结合硝基甲烷分子在最低三态动力学分解的可能性,可以认为在相同条件下,硝基甲烷材料在撞击条件下,分子沿C-N键分裂生成硝基和甲基的反应在最低三态分子分解的可能性较大。文章用量化计算从分子构型、频率分析和势能面扫描方面对分析结论进行了加强和确定。并且,依据多声子迁移理论对硝基甲烷分子基态键离解过程、基态到三态激发过程和最低三态活化过程中的声子迁移进行了初步分析。     

第一性原理研究GaP的电子结构、光学性质及各向异性

利用基于密度泛函理论(DFT),采用赝势平面波方法和广义梯度近似法(GGA)研究了闪锌矿ZB结构和盐岩RS结构GaP的基态电子结构、光学性质,根据能带理论初步研究GaP基态能带结构、总态密度(DOS)和分波态密度(PDOS),并计算出吸收系数,反射率,复介电函数,复折射率及能量损失函数.还计算了闪锌矿结构的GaP的各向异性.     

Stroh Formalism and Rayleigh Waves

The Stroh formalism is a powerful and elegant mathematical method developed for the analysis of the equations of anisotropic elasticity. The purpose of this exposition is to introduce the essence of this formalism and demonstrate its effectiveness in both static and dynamic elasticity. The equations of elasticity are complicated, because they constitute a system and, particularly for the anisotropic cases, inherit many parameters from the elasticity tensor. The Stroh formalism reveals simple structures hidden in the equations of anisotropic elasticity and provides a systematic approach to these equations. This exposition is divided into three chapters. Chapter 1 gives a succinct introduction to the Stroh formalism so that the reader could grasp the essentials as quickly as possible. In Chapter 2 several important topics in static elasticity, which include fundamental solutions, piezoelectricity, and inverse boundary value problems, are studied on the basis of the Stroh formalism. Chapter 3 is devoted to Rayleigh waves, for long a topic of utmost importance in nondestructive evaluation, seismology, and materials science. There we discuss existence, uniqueness, phase velocity, polarization, and perturbation of Rayleigh waves through the Stroh formalism.

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The Table of Contents and Index are also provided as Electronic Supplementary Material for online readers at doi:      

The age pattern of transitory mortality jumps and its impact on the pricing of catastrophic mortality bonds

To value catastrophic mortality bonds, a number of stochastic mortality models with transitory jump effects have been proposed. Rather than modeling the age pattern of jump effects explicitly, most of the existing models assume that the distributions of jump effects and general mortality improvements across ages are identical. Nevertheless, this assumption does not seem to be in line with what we observe from historical data. In this paper, we address this problem by introducing a Lee–Carter variant that captures the age pattern of mortality jumps by a distinct collection of parameters. The model variant is then further generalized to permit the age pattern of jump effects to vary randomly. We illustrate the two proposed models with mortality data from the United States and English and Welsh populations, and use them to value hypothetical mortality bonds with similar specifications to the Atlas IX Capital Class B note that was launched in 2013. It is found that the features we consider have a significant impact on the estimated prices.