An age structured population model in a spatially heterogeneous environment: Existence and uniqueness theory

This paper considers the existence and uniqueness of solutions of an age-structured population model in a spatially heterogeneous bounded environment. The model describes individual organism movement of diffusion and advection in the older life stage but assumes stationarity of individuals in the embryonic stage. The mathematical formulation is a nonlinear degenerate parabolic partial differential problem with non-locally integro-type initial-boundary conditions.     

An efficient preconditioner for electromagnetic integral equations using predefined wavelet packet basis

An approximate-inverse preconditioner based on the predefined wavelet packet (PWP) basis is proposed for the fast iterative solution of electromagnetic integral equations. The PWP basis is designed to achieve a sparse representation of the moment matrix and the preconditioner is constructed by inverting the block-diagonal approximation of the PWP-based moment matrix and transforming the results into the space domain. Numerical results show that the PWP preconditioner is effective in accelerating the convergence rate of iterative solution to moment equations. It is also demonstrated that by properly designing the block-diagonal matrix and computing the matrix elements, the total computational complexity and memory costs for the preconditioner can be kept to O(NlogN).     

多道HCN激光干涉仪在HL－1装置上的电子密度分布测量

本文描述了为测量ＨＬ－１装置电子密度分布而研制的多道远红外（ＦＩＲ）激光干涉仪系统及其特点。首次对装置在弹丸加料以及拉瓦尔（Ｌａｖａｌ）超声分子束注入实验条件下的等离子体电子密度时－空分布进行了观测和初步分析。同时，介绍一种处理密度相移信号的新方法。     

Routing of 100 Gb/s words in a packet-switched optical networkingdemonstration (POND) node

This paper presents the design and experimental results of an optical packet-switching testbed capable of performing message routing with single wavelength time division multiplexed (TDM) packet bit rates as high as 100 Gb/s. The physical topology of the packet-switched optical networking demonstration (POND) node is based on an eight-node ShuffleNet architecture. The key enabling technologies required to implement the node such as ultrafast packet generation, high-speed packet demultiplexing, and efficient packet routing schemes are described in detail. The routing approach taken is a hybrid implementation in which the packet data is maintained purely in the optical domain from source to destination whereas control information is read from the packet header at each node and converted to the electrical domain for an efficient means of implementing routing control. The technologies developed for the interconnection network presented in this paper can be applied to larger metropolitan and wide area networks as well     

A Quasilinear Hierarchical Size-Structured Model: Well-Posedness and Approximation

A finite difference approximation to a hierarchical size-structured model with nonlinear growth, mortality and reproduction rates is developed. Existence-uniqueness of the weak solution to the model is established and convergence of the finite-difference approximation is proved. Simulations indicate that the monotonicity assumption on the growth rate is crucial for the global existence of weak solutions. Numerical results testing the efficiency of this method in approximating the long-time behavior of the model are presented.     

连续Nd:YAG激光器中Cr~(4 ):YAG被动调Q的稳定性和功率的提高

Ｃｒ４＋ＹＡＧ用于连续ＮｄＹＡＧ激光器被动调Ｑ，激光横模结构和纵模结构以及激光泵浦速率起伏等是引起调Ｑ不稳定的重要因素，运用一定的技术可以使调Ｑ稳定性得到根本性改善；此外应考虑Ｃｒ４＋ＹＡＧ热效应及光学薄膜的激光损伤     

推广的EZ模型中的普适性行为

探讨了推广EZ模型的可能性,并给出了相应的模型中人群大小分布函数的形式解.研究表明金融市场中不同大小的人群数目的交易人的数目在重新标度后将具有最广泛的普适性行为 关键词： 金融物理 人群效应 主方程     

Critical speeding-up in the local dynamics of the random-cluster model

We study the dynamic critical behavior of the local bond-update (Sweeny) dynamics for the Fortuin-Kasteleyn random-cluster model in dimensions d=2, 3 by Monte Carlo simulation. We show that, for a suitable range of q values, the global observable S2 exhibits "critical speeding-up": it decorrelates well on time scales much less than one sweep. In some cases the dynamic critical exponent for the integrated autocorrelation time is negative. We also show that the dynamic critical exponent zexp is very close (possibly equal) to the rigorous lower bound alpha/nu and quite possibly smaller than the corresponding exponent for the Chayes-Machta-Swendsen-Wang cluster dynamics.     

Stochastic first-order methods for convex and nonconvex functional constrained optimization

Mathematical Programming - Functional constrained optimization is becoming more and more important in machine learning and operations research. Such problems have potential applications in...     

Highly Strong Interaction between Fe/Fe3C Nanoparticles and N-Doped Carbon toward Enhanced Oxygen Reduction Reaction Performance

Transition metal compounds anchored on N-doped carbon (NC) show intrinsic activity and stability for oxygen reduction reaction (ORR). However, the interaction between the transition metal compounds and NC still needs to be strengthened for electron transfer at the compounds/carbon interface. Herein, Fe/Fe₃C hybrid nanoparticles encapsulated into N-doped carbon (Fe@NC) are used as high-performance ORR catalysts. Benefiting from the strong interaction at Fe/Fe₃C nanoparticles/NC interface, the electrons can transfer from Fe/Fe₃C hybrid nanoparticles to NC, redistributing the electron density of active sites and promoting the ORR process. The as-synthesized Fe@NC exhibits outstanding ORR catalytic activity with an onset potential of 1.01 V and a half-wave potential of 0.92 V in alkaline media. It also shows prominent cycling stability and tolerance to methanol crossover, superior to Pt/C catalyst. The theoretical analysis reveals that the Fe nanoparticles have regulated the electron distributions at the heterojunction interface. The Gibbs free energy diagrams for ORR illustrate that the rate-determining step is the conversion of OH* to OH⁻. In situ Raman spectra give evidence of O-containing intermediates to prove the ORR process.