螺旋蛋白质模型的精确解

蛋白质是生命所必须的一类有机生物大分子,其螺旋结构对其在生命体中的作用有着重要的影响,对螺旋结构的研究一直是人们关注的焦点.文章运用辅助微分方程方法,双曲正切函数展开法和辅助双函数法,构造并求得了螺旋蛋白质螺旋链模型方程组的几组新的行波精确解.该结论还能用于探讨具有螺旋结构的生物大分子在传递各种信息时的规律及其对生命体生理功能作用的发挥机制.进一步解释了蛋白质分子的螺旋结构对生命体生理作用的复杂性.     

Camassa-Holm方程凹凸尖峰及光滑孤立子解

研究一类完全可积的新型浅水波方程Camassa-Holm方程的行波孤立子解及双孤立子解.引入凹凸尖峰孤立子及光滑孤立子的概念,研究得到该方程的行波解中具有尖峰性质的凹凸尖峰孤立子解及光滑孤立子解.同时利用Backlund变换给出该类方程的新的双孤立子解.     

非手征对称的共形可积Toda场的孤立子解

用Hirota方法给出了左右不对称的共形可积Toda场的单孤立子解和双孤立子解.     

Sine-Gordon方程孤立子解的表达式

本文研究Sine-Gordon方程
u_xt=sinu(A)
的反散射解.给出了(A)的孤立子解的简洁表达式,并讨论了单孤立子解和双孤立子解.     

Aharonov Bohm磁通对反铁磁链中的孤立子的影响

该文采用Holstein Primakoff变换、双子格模型、相干态表示、含时微扰原理和多 重尺度方法，研究了具有Aharonov Bohm磁通时，一维反铁磁链中的孤立子激发问题，探讨了Aharonov Bohm磁通对孤立子产生的效应，结果表明Aharonov Bohm磁通对孤立子的峰值、宽度、能量和自旋空间排列等均产生影响。     

针对壁面旋转变径管内螺旋流的压力应变项研究

通过壁面旋转变径圆管内螺旋湍流流动特征的分析，确定其切向速度场内涡流区为微团旋转主导的椭圆形流动，外涡流区为微团变形主导且受壁面旋转影响的双曲形流动.进而利用张量的不变量理论，引入旋转率张量与应变率张量的综合不变量作为模型系数，将适用于微团旋转主导的旋转湍流Reynolds应力压力应变项修正模型拓展到了非旋转效应主导的双曲形流动中.将修正压力应变项应用于壁面旋转变径圆管流场的模拟，并将结果与实测结果进行了对比，验证了修正模型的改进效果.     

最小双权树

本文根据一个实例建立了在双权无向网络中求最小双权树的多目标网络模型，提出了最小双权树和临界最小树子图的概念，并给出了这个模型的一个有效算法．     

螺旋型旋风分离器两相流场的数值模拟

对螺旋型旋风分离器进行了两相流场的三维数值模拟．气体流场通过求解三维N-S方程得到,湍流模型采用了雷诺应力模型．计算结果表明,旋风分离器内部的流场分为两部分:螺旋通道内比较稳定的流场和筒体中心区域的复合涡结构流场．对颗粒运动轨迹的计算表明,颗粒在入口处的初始位置对颗粒分离有比较显著的影响．同时得到了不同入口速度下颗粒的分级效率曲线,并给出了气体流量对旋风分离器性能的影响,结果显示:气体流量的增加会提高分离效率,但同时导致压力损失的急剧增加．     

数学年刊 第27卷B辑第2期(2006)目次和提要

Ricci 曲率和基本群忻元龙在 Ricci 曲率的一定条件下,对体积增长作细化估计,从而推广了 J．Milnor(1968)的二个基本群增长的经典结果． Ricci 孤立子的几何曹怀东 Ricci 孤立子一方面是爱因斯坦(Einstein)度量的自然推广,另一方面也是汉密尔顿(Hamilton) Ricci 流的特殊解,文中介绍了 Ricci 孤立子研究中的一些新进展及其在 Ricci 流的奇异性研究中的     

区间[-1，1]上的α尺度双正交多小波的构造

本文研究了一元α尺度紧支撑、双正交多小波的构造．在区间[-1，1]，给出了利用α尺度双正交尺度向量构造α尺度双正交多小波的推导过程得到了一种有效的小波构造算法，并给出了数值算例．     

Soliton dynamics in the helix polypeptide chains

The coupling model between the three hydrogen-bonded chains to describe the helix polypeptide chain is investigated. The kink group, envelope-soliton and breather groups are obtained, in which the symmetric and asymmetric kink groups correspond to the local contraction (or expansion) and twisting deformed regions of helix polypeptide chain, respectively. The piezoelectric stress coefficient to describe the piezoelectric phenomenon arising from the local twisting deformation of the helix polypeptide chain is defined. The symmetric breather group will occur in the dipole radiation. The motion of asymmetric envelope-soliton group will result in the wriggle of the helix polypeptide chain, just like that of an earthworm. We show that (i) the twisting deformed structure of the helix polypeptide chain is more stationary than the uniform helix structure. (ii) The piezoelectric effect of collagen fibril of bone originates from the piezoelectricity of the helix polypeptide chain. (iii) The static attraction between the intrinsical charges arising from deformation of the helix polypeptide chain is advantageous to fold protein chain into the tertiary structure. A “gear model” ( or “molecule motor model”) to explain the mechanism of muscle contraction is suggested.     

A parametric scheme for the numerical solution of the Boussinesq equation

A parametric scheme is proposed for the numerical solution of the nonlinear Boussinesq equation. The numerical method is developed by approximating the time and the space partial derivatives by finite-difference re placements and the nonlinear term by an appropriate linearized scheme. The resulting finite-difference method is analyzed for local truncation error and stability. The results of a number of numerical experiments are given for both the single and the double-soliton wave.     

A predictor-corrector scheme for the numerical solution of the Boussinesq equation

A fourth order in time and second order in space scheme using a finite-difference method is developed for the non-linear Boussinesq equation. For the solution of the resulting non-liner system a predictor-corrector pair is proposed. The method is analyzed for local truncation error and stability. The results of a number of numerical experiments for both the single and the double-soliton waves are given.     

Fourth-order compact solution of the nonlinear Klein-Gordon equation

In this work we propose a fourth-order compact method for solving the one-dimensional nonlinear Klein-Gordon equation. We apply a compact finite difference approximation of fourth-order for discretizing spatial derivative and a fourth-order A-stable diagonally-implicit Runge-Kutta-Nyström (DIRKN) method for the time integration of the resulting nonlinear second-order system of ordinary differential equations. The proposed method has fourth order accuracy in both space and time variables and is unconditionally stable. Numerical results obtained from solving several problems possessing periodic, kinks, single and double-soliton waves show that the combination of a compact finite difference approximation of fourth order and a fourth-order A-stable DIRKN method gives an efficient algorithm for solving these problems.     

供应链节点企业隐性知识转化的博弈分析

供应链隐性知识与显性知识的相互转化形成螺旋上升的价值创造过程,其中隐性知识是核心.在由多个制造商和多个零售商组成的两级复杂供应链中,考虑知识的含量与成本是负线性相关的情况下,制造商和零售商依照自身利益的最大化进行隐性知识转化决策,使得其存在背离隐性知识显性化的行为.但是在多阶段中,其它节点企业会采取一定的惩罚措施,最终使得其重新回归到隐性知识显性化的行为上.     

Bäcklund transformations and abundant exact explicit solutions of the Sharma-Tasso-Olver equation

By using an extension of the homogeneous balance method and Maple, the Bäcklund transformations for the Sharma-Tasso-Olver equation are derived. The connections between the Sharma-Tasso-Olver equation and some linear partial differential equations are found. With the aid of the transformations given here and the computer program Maple 12, abundant exact explicit special solutions to the Sharma-Tasso-Olver equation are constructed. In addition to all known solutions re-deriving in a systematic way, several entirely new and more general exact explicit solitary wave solutions can also be obtained. These solutions include (a) the algebraic solitary wave solution of rational function, (b) single-soliton solutions, (c) double-soliton solutions, (d) N-soliton solutions, (e) singular traveling solutions, (f) the periodic wave solutions of trigonometric function type, and (g) many non-traveling solutions. By using the Airy’s function and the Bäcklund transformations obtained here, the exact explicit solution of the initial value problem for the STO equation is presented. The variety of the structure of the solutions for the Sharma-Tasso-Olver equation is illustrated.     

Some string matching problems from Bioinformatics which still need better solutions

Bioinformatics, the discipline which studies the computational problems arising from molecular biology, poses many interesting problems to the string searching community. We will describe two problems arising from Bioinformatics, their preliminary solutions, and the more general problem that they pose. The first problem is searching for α-helices in protein sequences. This particular instance of the search is based on matching of hydrophobicity/hydrophilicity. We find an algorithm which is linear in the sequence length for fixed helix length and is O(nlogn) for any helix length. The second problem is on matching probabilistic sequences against sequences or against other probabilistic sequences. In both cases we derive efficient formulas to compute scores according to a Markovian model of evolution.     

Protein dynamics: Complex by itself

Biological functions are intimately rooted in biopolymer dynamics. It is commonly accepted that proteins can be considered as complex systems, but the origin of such complexity is still not fully understood. Moreover, it is still not really clear if proteins are true complex systems or complicated ones. Here, molecular dynamics simulations on a two helix bundle protein have been performed, and protein trajectories have been analyzed by using correlation functions in the frequency domain. We show that even a simple protein exhibits the hallmarks of complex systems. Moreover, the molecular bases of this complex behavior are possessed completely by the protein itself, because such complexity emerges without considering the solvent explicitly. © 2012 Wiley Periodicals, Inc. Complexity, 2012     

空间圆柱螺旋线的NURBS表示

O．引言用B样条方法或B6zier方法来表示自由曲线、曲面，是在CAD／CAM技术中广泛使用的数学手段．但是由于它们都不能精确地表示除抛物线或抛物面以外的圆锥曲线与初等二次曲面，因此近年来，另一种形式的参数样条-一参数有理多项式方法占据了主导地位．非均匀有理B样条（简称NURBS）已被国际标准组织（ISO）于1991年正式颁布为关于工业产品几何定义的STEP国际标准，将其作为定义产品形状的唯一数学方法．越来越多的CAD系统采用NURBS曲线与曲面来建立图形库，研究各种曲线与曲面的NURBS表示无疑是很有意义的．在描述圆锥曲线…     

General Helices with Timelike Slope Axis in Minkowski 3-Space

In the present paper, we consider the general helices in Minkowski 3-space to have a constant timelike slope axis. As a result, we show that there exists no pseudo null helix with constant timelike slope axis or spacelike helix with timelike principal normal and constant timelike slope axis. Moreover, we obtain the parametric equations of spacelike helix with spacelike principal normal, timelike helix and null Cartan helix with timelike slope axis. We also give some related examples and their figures.