中美贸易和美国对华直接投资--基于1984-2002年数据的实证分析

通过利用1984—2002年的数据,使用协整分析和格兰杰因果关系检验法对中美贸易和美对华投资的关系进行了检验。结果表明,两者之间有着长期稳定的关系。     

Analysis on the Spatio-Temporal Changes of Sustainable Land Use in Tibet

By constructing evaluation indicator system of sustainable land use of Tibet from three aspects of ecological environment, economic development, resources and social advancement, this article studies the following contents respectively in two dimensions of time and space： the changes of sustainable land use of Tibet in recent 20 years and spatial characteristics of sustainable land use of Tibet in 2002. The following conclusions can be drawn from evaluation results .① With regard to com- prehensive evaluation value of sustainable land use, the trend of Tibet sustainable land use evaluation values from 1983 to 2002 are very close to the comprehensive evaluation values of ecological environment, which is up trend; ② sustainable utilization degree of land use in eastern region of Tibet is much higher than that of western region. ③ the sustainable land use evaluation value of Nyingtri County is the highest, and the counties with relatively higher land sustainable use values include Lhasa, Lhoka, Chamdo. While Nakchu, Ngari, Shigatse counties have the relatively lower evaluation values; ④ By analyzing each evaluation indicator＇s weight on sustainable land use, it can be concluded that the key limiting factors of sustainable Tibet land resource utilization are land desertification, grassland degradation and low economic level.     

线性随机系统基于观测器的反馈镇定

针对控制系统测量输出产生的乘性噪声问题,提出基于观测器的反馈控制设计算法.首先,引入状态误差变量,导出反馈控制下It8型随机微分方程描述的闭环系统.其次,运用复合Lyapunov函数方法并结合随机分析技术,分析闭环系统的均方指数稳定性和几乎必然稳定性,并建立输出反馈控制器存在的充分条件.基于此条件给出了控制增益矩阵和观测器增益矩阵的参数化设计算法.最后,通过倒立摆模型的数值仿真,验证所提出控制策略的有效性.     

Narrow-band tomographic radar imaging of precession cone targets

The principle and method of the narrow-band tomo-graphic radar imaging (NBTRI) of the precession cone target are studied. Firstly, the motion model and electromagnetic scattering characteristics of the precession cone target are introduced. Secondly, based on the traditional NBTRI algorithm, a novel narrow-band tomography clean radar imaging (NBTCRI) algorithm is proposed to enhance the image quality of NBTRI results. In addition, the resolution performance of the NBTRI algorithm is analyzed. Finally, based on the ideal scattering point model, this paper discusses the relationship between the precession angle and the estimated target size from NBTRI results. By using the target’s chamber data, NBTRI and NBTCRI results of the precession cone target are further analyzed, which indicates the effectiveness of the proposed method.     

模糊神经网络在锅炉煤种辨识中的应用

针对目前很多工业锅炉燃烧煤种发生变化时,控制效果下降,燃烧效率降低等问题,设计了一套在线煤种辨识系统,其核心采用模糊神经网络来构建辨识模型,综合了线性辨识方法和非线性神经网络建模方法的优势。能够利用过程历史数据辨识对象模型。利用试验仿真平台对该方法进行了仿真验证,结果显示了该方法辨识误差在2%以内,且具有适应范围广、计算方法简单等优点,该方法还可应用于锅炉其他重要热工参数的软测量,有很高的应用推广价值。     

交换环上上三角矩阵的乘法自同构（英文）

设R是有单位无的交换环,并且2在R中可逆.记T_n（R）是由R上所有的n×n上三角矩阵组成的乘法半群.本文将决定T_n（R）上的所有乘法自同构.     

传统网络总时差计算方法的商榷

本文揭示了传统网络构图模型系统结构的不相容性，从而实现了传统网络总时差的计算是错误的论证。     

分形与分维及在地球物理学中的应用

本文概述了分形几何的产生和发展,论述了分形与分维的基本概念,同时介绍了分形理论在地震科学、沉积岩结构及电导率、油田开发过程中的粘性指进等方面的应用。     

分形生长DLA模型及其在流体驱替中的应用

分形生长ＤＬＡ模型的出现，深化了人们对非平衡生长现象的认识，揭示和解决了一些传统方法难以解决的问题．各种改善和修正的ＤＬＡ模型的出现，丰富了人们对ＤＬＡ集团的认识，ＤＬＡ集团不再具有统一的无序分形各向同性的特征，而是和网格及模型有关．在ＤＬＡ模型中考虑粒子吸附几率后，可以反映流体驱替过程中界面张力效应，尤其是可用于模拟流体驱替过程中粘性指进现象的动力学演化过程，为描述粘性指进现象提供了一个新的、有效的手段．