Positive Steady States of a Prey-predator Model with Diffusion and Non-monotone Conversion Rate

In this paper, we study the positive steady states of a prey-predator model with diffusion throughout and a non-monotone conversion rate under the homogeneous Dirichlet boundary condition. We obtain some results of the existence and non-existence of positive steady states. The stability and uniqueness of positive steady states are also discussed.     

Is Kano-Nucleon Interaction Consistent with Pentaquark θ^＋

The quark-delocalization colour-screening model is employed to calculate the effective potential between nucleon and kaon. The results show that the potentials are attractive in the I = 0 channel and repulsive in the I = 1 channel. The interactions are very weak between K^＋n or K^0p due to the cancellation between I = 0 and I = 1. It is possible to have a high s-wave resonance （1615 MeV）, but the width may be too wide to be observed in the experiments.     

Method for vessel attitude estimation by spatial correlation function for bottom reverberation

Under the assumption that the sea bottom is an almost-flat and randomly rough thin layer, a spatial correlation model for bottom reverberation is constructed. At high signal noise ratio, the phase of the spatial correlation function is the product of sound wave number and the vertical vector between two hydrophones. In a nominally horizontal plane, roll and pitch bring on the vertical vector between the hydrophones. Then an equation including roll, pitch and the phase of the spatial correlation function is found. If a parallelogram can be constructed by 3 hydrophones and the rat ios of its acreage to diagonals are not smaller than half of the wavelength, roll and pitch can be obtained analytically or by optimal method. However, the ranges of roll and pitch are restricted because of the phase ambiguity. Using Fisher information matrix, the Cramer-Rao lower bound is obtained. Results from computer simulation and sea test data prove the feasibility of the method.     

BNCT优化网格设计及相关算法研究

用MCNP蒙特卡罗程序模拟了硼中子俘获治疗(BNCT)3种国际基准网格模型, 并与 修正的Snyder椭球模型进行了比较. 在此基础上, 给出了一种保质量守恒、内存量少、易于产生输入文件的4种基本材料成分的BNCT网格模型. 计算结果表明, 在4mm网格下, 新模型可以达到基准模型的精度; 根据解析模型剂量随深度的变化规律, 研究构造了多网格组合模型, 在重要区域计算精度不损失的条件下, 计算时间大大缩短. 最后研究给出了一个既保证精度、又在可接受的时间内完成剂量计算的模型、样本数和相应的算法, 它基本上满足临床BNCT的要求.     

Phase-Locked Fibre Array for Coherent Combination and Atmosphere Aberration Compensation

We report a fibre amplifier array that not only achieves coherent beam combination by compensation of phase noises of fibre amplifier, but also accomplishes correction of atmosphere aberration. It is of master-oscillatormultiple-amplifier （MOPA） configuration, which can be phase-locked by the multidither principle or heterodyne detection principle. First laboratory experiments of atmosphere aberration compensation of a three-element fibre amplifier array are reported. The atmosphere aberration is created by a phase screen in the experiment. The phase changes of the beam, which are introduced by the fibre amplifier and the phase screen, are both detected by the heterodyne detection method. Phase modulators are controlled to compensate for the phase in the three paths. No matter whether there is a phase screen producing atmosphere aberration or not, the dim dynamic interference fringes in the far field turn to a clear and stable pattern, and the peak intensity is maximized. It is indicated that the fibre amplifier array is phase-locked, and coherent combination of the three beams is achieved. It can be used not only to obtain high power fibre laser array but also in laser space communication.     

选择性远程DEPT~(13)C NMR新技术用于新阔叶千里光碱氮氧化合物的结构测定和谱峰归属研究

从湖北蟹甲草根茎中分得一个新的生物碱,选择性远程DEPT~(13)C NMR新技术用于识别NMR信号归属和连接被季碳及杂原子分割的质子自旋系统,确定其结构为新阔叶千里光碱的氮氧化物,如(1)所示。     

电流控阈技术及二值 I2L 施密特电路设计

电流控阈技术及二值Ｉ~２Ｌ施密特电路设计黄瑞祥，杭国强（杭州大学电子工程系杭州３１００２８）在数字电路中，以往对施密特电路的分析与研究大多局限于用电压信号来表示逻辑值的电路，例如ＴＴＬ、ＣＭＯＳ、ＥＣＬ等电路［１－３］．然而，对于以电流为信号的电流型?..     

α－蒎烯／苯乙烯共聚产物微臭氧化－薄层层析分离研究

建立了一种α－蒎烯／苯乙烯共用产物分离分析微臭氧化－薄层层析法．通过标准样品的分离和ＩＲ、ＮＭＲ表征以及共聚体组分的测定，表明这种方法对α－蒎烯／苯乙烯均聚体混合物和共聚产物中均、共聚体的分离完全，样品回收率很高，解决了α－蒎烯／苯乙烯均、共聚体无法分离分析的难题．     

光学双稳性临界点的相变行为

本文详细地讨论了光学双稳性(OB)的临界现象。理论分析主要以忽略量子涨落的Fokker-Plank方程的静态解为基础。结果发现,OB的临界现象可以纳入Landau二级相变理论的框架,并且有关临界指数之间的关系也服从标度律。 关键词：