半线性双调和方程解的存在性

考虑了有界光滑区域ΩR~d,d=2,3上的一类半线性双调和方程.非线性项φ（｜▽u｜）是由｜▽u｜~p产生的.应用Schaefer不动点定理证明了当d=2（或d=3）,p满足2≤p〈∞（或2≤p≤6）时,该问题的解是存在的,并且解是局部唯一的.     

竞争-竞争-互惠交错扩散模型的整体解

应用能量估计方法和bootstrap技巧证明了竞争-竞争-互惠交错扩散模型在空间维数小于6时古典解的整体存在性.当反应函数的系数满足一定条件时,应用Lyapunov函数获得了该模型解的收敛性.     

求解用户平衡与系统最优模型的新算法

近些年,国内外许多学者针对交通规划提出了诸如用户平衡(UE)、系统最优(SO)等模型,但由于交通网络的复杂性,这些模型的求解相对困难,考虑到在一般的UE、S0模型中,其约束条件为线性约束与非负约束,给出一种求解交通规划模型的新算法,算法不需使用任何线搜索,只要通过求解一个简单的二次规划问题得到下降方向即可,最后,将该算法应用到简单的交通网络中,并通过与相继平均法(MSA)进行比较,验证了该算法的收敛速度较快。     

Photoconductivity and photoreflectance studies of quantum-wells and superlattices

We have performed room-temperature in-plane photoconductivity and photoreflectance measurements on various types of GaAs/AlAs quantum-wells and superlattices. The photoconductivity spectra of samples with even a few (1 to 7) quantum-wells show sharp excitonic structures superimposed on the bulk GaAs signal, and provide a useful alternative to absorption spectra. The photoreflectance spectra are demonstrated experimentally to follow the third derivative of the photoconductivity spectra, as previously reported for bulk materials, even though the mechanism of photoreflectance must be different in the present two-dimensional systems.     

Nuclear magnetic moments in the hybrid quark-hadron model

A model (HQHM) of quark deconfinement at short distances, and baryon and pion degrees of freedom at large distances, has been shown to give a good representation of few-nucleon systems up to momentum transfers of about 1 GeV/c. This model is extended to complex nuclei. In a detailed HQH shell model calculation the magnetic dipole moments of mediummass closed shell ±1 nuclei are shown to be in good agreement with experiment, even with a sizable probability of six-quark matter. Preliminary calculations of M1 transitions give damping in the direction indicated by experiment.     

Phonon dispersion relations of the A15 compound Nb3Sb

We have calculated the phonon dispersion relations of the A15 compound Nb₃Sb using an angular force model approach, the analysis being restricted to third neighbour interactions only. The force constants have been evaluated by fitting them to the measured values ofphonons at the zone centre. Good agreement has been observed between theory and the available experimental results. It has been inferred that the angular forces are not of significant importance between different atoms (Nb-Sb). The physical aspects for the same are discussed.     

Asymptotic distribution of products of sums of independent random variables

In the paper we consider the asymptotic distribution of products of weighted sums of independent random variables.     

Asymptotic analysis of microscopic impenetrability constraints for atomistic systems

We analyze systems of atomistic interactions on a triangular lattice allowing for fracture under a geometric condition on the triangles corresponding to a microscopic impenetrability constraint. Such systems can be thought as a computational simulation of materials undergoing brittle fracture. We show that in the small-deformation regime such approximation can be validated analytically in the framework of variational models of fracture. Conversely, in a finite-deformation regime various pathologies show that the continuum approximation of such a system differs from the usual variational representations of fracture and either needs new types of formulations on the continuum, or a proper interpretation of the atomistic constraints limiting their range and adapting them to a dynamical framework.