Breaking the Symmetry in a Car-Following Model

A wide class of microscopic car-following traffic models deals with a system of ODEs describing N cars driving on a circular highway. The symmetry of the road naturally leads to (quasi-)stationary solutions and to an analysis of their stability. Breaking this symmetry with small perturbations we show the existence of a branch of some special solutions that occur instead of the stationary points. Those solutions can be interpreted in reality, they describe the behavior of the cars on the road as expected. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

玻璃划分的数学模型

本文讨论了玻璃合理划分问题,建立了玻璃划分的数学模型．该模型既使得坯料用量最优,也考虑了余料尽可能少,同时划分得到的各种规格的成品玻璃尽可能刚好满足需要,数值计算结果表明该模型是有效和合理的．     

On the Solutions of a $$$$-Dimensional Model for Epitaxial Growth with Axial Symmetry

In this paper, we study the evolution equation derived by Xu and Xiang (SIAM J Appl Math 69(5):1393–1414, 2009) to describe heteroepitaxial growth in \(2+1\) dimensions with elastic forces on vicinal surfaces is in the radial case and uniform mobility. This equation is strongly nonlinear and contains two elliptic integrals and defined via Cauchy principal value. We will first derive a formally equivalent parabolic evolution equation (i.e., full equivalence when sufficient regularity is assumed), and the main aim is to prove existence, uniqueness and regularity of strong solutions. We will extensively use techniques from the theory of evolution equations governed by maximal monotone operators in Banach spaces.     

A Simple Cluster Model for the Liquid–Glass Transition

Using the classical distribution-function approach to simple liquids, we estimate the orientational interaction between clusters consisting of a particle and its nearest neighbors. We show that there are density and temperature ranges where the interaction changes sign as a function of the cluster radius. On this basis, the corresponding model of interacting cubic and icosahedral clusters (of the type of a spin glass model) is proposed and solved in the replica-symmetric approximation. We show that the glass order parameter grows continuously on cooling and the replica-symmetry-breaking temperature can be identified with the glass transition temperature. We also show that on cooling a system of particles with a Lennard-Jones interaction, cubic clusters freeze first. The transition temperature for icosahedral clusters is somewhat lower; therefore, the cubic structure of the short-range order is more likely in a Lennard-Jones glass near transition.     

轴对称金属模具电磁热裂纹止裂中热应力场的分析

为求解金属模具脉冲放电止裂瞬间裂纹尖端附近的热应力场,选择具有半埋藏环形裂纹的金属凹模为研究对象,采用复变函数方法求解了凹模内外环面均匀通入强脉冲电流放电止裂时的热应力场．理论分析结果证实:由于放电瞬间脉冲电流的绕流集中效应,使金属凹模内部环形裂纹尖端附近金属迅速升温,金属熔化形成堆焊,并由于瞬间温升产生热压应力场．研究结果表明:应用电磁热效应止裂技术可以减小裂纹尖端的应力集中,形成的热压应力场有效地阻止金属模具中干线裂纹源的开裂趋势,达到了裂纹止裂目的．     

Symmetry Breaking of Extremals for the Caffarelli-Kohn-Nirenberg Inequalities in a Non-Hilbertian Setting

We provide an explicit necessary condition to have that no extremal for the best constant in the Caffarelli-Kohn-Nirenberg inequality is radially symmetric.     

<Emphasis Type="Italic">p</Emphasis>-Adic Pseudodifferential Operators and Analytic Continuation of Replica Matrices

We consider the procedure for analytic continuation of the replica matrix. We formulate a particular form of this procedure in which the analytic continuation is defined by a sequence of maps. Using this definition, we construct a solution that breaks the Parisi replica symmetry and find the corresponding p-adic pseudodifferential operator. __________ Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 144, No. 2, pp. 336–341, August, 2005     

Geometric Invariant Theory in a Model-Independent Analysis of Spontaneous Symmetry and Supersymmetry Breaking

Functions which are covariant or invariant under the transformations of a reductive linear algebraic group can be advantageously expressed in terms of functions defined in the orbit space of the group, i.e. as functions of a finite set of basic invariant polynomials. This fact and the tools of geometric invariant theory can be exploited in many physical contexts where the study of covariant or invariant functions is important, for instance in the determination of patterns of spontaneous symmetry and/or supersymmetry breaking in possibly supersymmetric quantum field theories of elementary particles, in the analysis of phase spaces and structural phase transitions in solid state physics (Landau's theory), in covariant bifurcation theory, in crystal field theory and in most areas of solid state theory where use is made of symmetry adapted functions. We shall present some elements of geometric invariant theory and illustrate some of the possible applications in the study of spontaneous symmetry and supersymmetry breaking.     

Navier-Stokes方程对称破坏分歧点的谱Galerkin逼近[英文]

本文研究了Navier-Stokes方程对称破坏分歧点的谱Galerkin逼近问题，构造了定常Navier-Stokes方程对称破坏分歧点扩充系统及其谱Galerkin逼近扩充系统，证明了谱Galerkin逼扩充系统解的存在性和收敛性，从而给出了Navier-Stokes方程对称破坏分歧点的谱Galerkin逼近，并给出了逼近的误差估计。     

Orientation ordering and the transition to the orientational glass state in fullerite C<Subscript>60</Subscript>

We propose a model for describing the low-temperature transition to the orientational glass state in solid molecular C₆₀ in the framework of a theory similar to spin glass theory. We find a replica symmetric solution and also break the replica symmetry. The obtained results agree with experimental data on the partial retention of the orientational long-range order in the glass phase and on the presence of a broad maximum on the curve corresponding to the temperature dependence of the orientational part of the heat capacity. __________ Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 155, No. 2, pp. 356–368, May, 2008.     

On a 1-D Model of Stress Relaxation in an Annealed Glass

A 1-D model of a slab of glass of a small thickness is considered. The governing equations are those of the classical 1-D linear viscoelasticity. A load due to the temperature gradients is assumed. The aim is to model the process called annealing. It is shown that an additional load due to structural strain is crucial for the success of the model. Algorithms of a numerical solution of the governing equations are proposed. Numerical results are presented and commented.     

Symmetry Reductions of the Combined KdV—mKdV Equation

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q-Symmetry in Condensed Matter Physics: an Effective Generalized Hubbard Model with Quantum Symmetry

Using the generalized LangFirsov transformation, we reduce the Hubbard model with phonons (which, under particular circumstances, has recently been shown to exhibit the quantum symmetry su(2)[su(2)]_q into an effective electron Hamiltonian. The effective Hamiltonian is explicitly proved to maintain the quantum symmetry, which survives even when relaxing one of the constraints on the Hamiltonian parameters that must hold in the model with phonons. We investigate under which circumstances some superconducting eigenstates of the effective Hamiltonian, which can be built thanks to the quantum symmetry, could become metastable. Bibliography: 12 titles.     

Description of the paramagnet-spin glass transition in the Edwards-Anderson model using critical-dynamics methods

We show that the paramagnet-spin glass transition can be described in the Edwards-Anderson model using critical-dynamics methods and taking the ultrametric topology of the temporal space into account. In the framework of the suggested approach, we derive the Vogel-Fulcher relation for the system relaxation time. We prove that the fluctuation-dissipation theorem holds for the given model if there is no relaxation-time hierarchy. __________ Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 147, No. 2, pp. 328–336, May, 2006.     

玻壳成型过程诱导残余应力的数值预测

建立了玻壳压制成型固化过程中残余应力预测的数值模拟模型,采用平行平板间玻璃熔体的固化问题来描述成型过程中残余应力形成的机理,并假定材料为热流变简单粘弹性材料．基于板壳理论,将产品视为平板单元的组合,并采用有限元法来求解,这种方法可以象全三维计算一样一层层地计算残余应力,非常适合复杂形状的薄压制成型产品．最后通过实验比较验证了所提出的模型和方法．     

Symmetry of positive solutions of an almost-critical problem in an annulus

We consider the subcritical problem & 0 & \qquad\textrm{in} \; A\\ u & = & 0 & \qquad\textrm{on} \; \delta A\\ \end{array} \right.$$" align="middle" border="0"> where A is an annulus in , , is the critical Sobolev exponent and 0$" align="middle" border="0"> is a small parameter. We prove that solutions of (I) which concentrate at one or two points are axially symmetric.Received: 7 July 2003, Accepted: 10 May 2004, Published online: 16 July 2004Filomena Pacella: Research supported by MIUR, project Variational Methods and Nonlinear Differential Equations.     

Symmetry breaking of an elliptic equation in expanding annuli

We obtain non-radial bifurcation from radial solutions of a semilinear elliptic equation in expanding annuli of \(\mathbb {R}^N\). To obtain the main results, we use a blow-up argument via the Morse index of the regular entire solutions of the equation

$$\begin{aligned} -\Delta u=\lambda u^p \quad \text {in}\quad \mathbb {R}^N. \end{aligned}$$

(0.1)

The main results of this paper can be seen as applications of the properties of regular entire solutions of (0.1).

     

随机波动率跳-扩散模型下外汇期权本外币对称公式

外汇期权本外币对称公式表示本币看涨/看跌期权与外币看跌/看涨期权用同类定价函数表示的等价关系.通过测度变换法指出本币测度下的Bates模型和Heston模型在外币测度下保持模型类型不变,并且由此证明这两个模型下的本外币对称公式,其中的定价函数由Attari公式给出.数值分析给出了本外币对称公式的应用示范,并且详细分析了Attari公式的计算速度优势.     

聚氯乙烯接近玻璃化转变温度时的蠕变行为研究

利用动态力学分析仪,详细研究了小应力作用下聚氯乙烯（PVC）接近玻璃化转变温度（63℃）时的短期蠕变性能．根据Struik-Kohlrausch (SK)方程及Struik移位方法,分析了物理老化对PVC瞬时蠕变柔量的影响,并提出了基于多松弛机制的新模型定量描述初始蠕变柔量、松弛时间和形状因子．结果表明:SK方程虽可表征不同老化时间下PVC的蠕变性能,但通过Struik移位方法却无法获得理想的主曲线,且初始蠕变柔量、松弛时间、形状因子和蠕变率均受物理老化显著影响,并在双对数坐标下随老化时间呈明显的非线性变化;新模型不仅揭示了物理老化控制参量的演化规律,而且极好地预测了PVC在物理老化进程中的高温蠕变行为．