基于次近邻扩散聚集生长的复杂网络及其分析

提出了一种基于次近邻扩散聚集生长的复杂网络模型生成法则.用于刻画与扩散置限凝聚等复杂现象相关的实测对象.通过细致的计算机仿真模拟,初步研究了生成半随机复杂网络的一些典型数字特征:包括度分布、网络直径、平均路径长度、平均聚类系数等.研究结果表明,按照提出的方法产生的复杂网络具有短的平均路径长度、较高的平均聚类系数、具备明显的齐次网络特性.同时,在变动跳动概率之差时,生成网络直径、平均路径长度、网络平均聚类系数等呈现规律性变化;且生成网络直径、平均路径长度与网络平均聚类系数呈负相关关系.     

Acetone hydrogenation in exothermic reactor of an isopropanol–acetone–hydrogen chemical heat pump: effect of intra-particle mass and heat transfer

Intra-particle mass and heat transfer plays an important role in performance of the exothermic fixed-bed reactor for an isopropanol-acetone-hydrogen chemical heat pump. In this work, an exothermic fixed-bed reactor model, taking into account the actual packing structure, is established in the commercial software Fluent. A 120° segment of a tube with tube-to-particle diameter ratio （n） of 4, where realistic particles are packed and set to porous media, is used to simulate the 3D external flow, concen- tration and temperature fields in the exothermic packed-bed reactor. The influence of catalyst particle diameter （dp） and micropore diameter （do） on the intra-particle temperature, species distribution, reaction rate and selectivity is dis- cussed. The appropriate dp and do are obtained. Simulation results showed that intra-particle temperature gradient is not obvious. Large dp and small do lead to remarkable gradient of reaction rate inside the catalyst particle and the decrease in the catalyst efficiency and reduce the acetone conversion and the selectivity in isopropanol. The optimal results reveal that the spherical catalyst with dp of 1 mm and dpore of 10 nm is appropriate for high-temperature acetone hydrogenation.     

浅析复杂地形对污染物扩散的影响——火电厂环评污染气象分析实例总结

利用中尺度气象模式AERMOD,结合实际工程案例,通过资料分析与模拟计算,研究了伊犁冬季NO2随地形复杂程度不同的扩散特点,同时通过对国内外关于复杂地形对大气污染物扩散的研究分析,对复杂地形上大气污染物扩散以及湍流风场的研究分别作了介绍,同时列出了求解湍流风场和污染物扩散的基本方程组,为解决此类问题提供参考。     

输运过程和输运系数的推导

气体的输运过程,是非平衡态向平衡态的过渡过程。严密、精确的讨论其微观实质是本章的重点。文章给出输运过程和输运系数简易的推导方法。这种方法不仅适合在普通物理中采用而且适合于基础差的少数民族学生进行教学。     

Saturation models: A brief survey and critique

The authors review and compare the papers in this issue on saturation and logistic growth with special emphasis on the structure of the underlying probability models. Influence diagrams are used to illustrate the dependence and independence assumptions and the way in which uncertainty is reflected in key model assumptions and parameters characterizing the models.     

带有非线性局部化反应源项的抛物方程组的爆破估计

讨论了一类带局部化非线性反应项的扩散方程组的爆破估计问题。在一些合理的假设条件下，对于初值问题，得到了解的爆破条件和爆破速率；对于相应的第一初边值问题，不仅建立了解的爆破估计，而且还获得了边界层估计。     

PESC电池扩散工艺的改进及分析

由于硅单晶质量的提高及背表面场和减反射膜技术的应用,电池的短路电流已接近理论极限值,因此其性能的改进就取决于发射区的优化.本文论述了一种改进的扩散工艺——二次扩散工艺.其主要特点是提高氧化温度,利用氧化过程的高温改善发射区杂质分布,从而减少“死层”的影响.文中分析并计算了二次扩散(氧化)后的杂质分布和结深的变化,并讨论了二次扩散对发射区少于复合的影响及工艺条件对发射区各参数的影响.     

ANALYSIS OF THE MECHANISM MODELS OF TECHNOLOGICAL INNOVATION DIFFUSION＊

This paper analyzes the mechanism and principle of diffusion of technology diffusion on the basis of quantitative analysis. Then it sets up the diffusion model of innovation incorporating price, advertising and distribution, the diffusion model of innovation including various kinds of consumers, and the substitute model between the new technology and the old one applied systems dynamics, optimization method, probabilistic method and simulation method on computer, Finally this paper concludes with some practical observations from a case study.     

具有扩散率非自治Ayala模型的持续生存与周期解

本文讨论非自治Ayala系统在无扩散丛有扩散时持续生存和灭绝的充分条件,以及该系统为周期系统时存在唯一严格正的全局稳定周期解的条件。     

基于分数阶超混沌的新图像加密算法

分数阶混沌系统具有复杂的动力学特性,因此在图像加密中具有更高的安全性.首先,利用离散logistic混沌系统对彩色数字图像的三基色平面进行置乱.然后,利用分数阶CYQY超混沌系统对置乱图像的三基色通道进行逐像素替换.为提高明文对密文的敏感性,通过明文图像产生的小数对作为密钥的阶次、参数和系统初始值等进行扰动,理论分析和对彩色Baboon图像的仿真实验均表明,该算法加密效果好且能有效抵抗各种攻击.