弱化系统耦合度方法与应用

许多工业过程控制系统都具有变量间的耦合,这些系统经常存在一、二个耦合度最大的,只要设法将这一、二个子系统从整体系统分离出来,就可以得到一个弱耦合度的系统。本文介绍一种弱化系统耦合度方法,以及这种方法在球磨机控制中的应用。

使用蜜罐分析一种蠕虫病毒的运行机制

本文使用VMWare以弱化系统方式在宿主机配置高交互的蜜罐系统。配置过程包括安装虚拟操作系统、系统补丁和杀毒程序、系统监视、数据包捕获软件等。利用该系统捕获了一种网络病毒,通过对捕获到的蠕虫病毒的攻击过程的记录和分析,了解了其特征和网络病毒运行机制,为进一步采取防范措施提供参考。

Research Progress of Vulnerability Assessment on Grassland Ecosystem under Climate Change

[Objective] The aim was to review on vulnerability evaluation of grassland ecosystem under climate change.[Method] In the research,vulnerability evaluation methods of ecosystem under climate changes,at home and abroad,and the related cases and research progress in China were reviewed.In addition,the future of evaluation research was predicted.[Result] Ecosystem vulnerability to climate change is an important part of climate change research.It is necessary and urgent to improve evaluation methods and reduce uncertainty of future vulnerability evaluation to make evaluation more comprehensive and objective.Furthermore,evaluation on effects of human activity on natural ecosystem vulnerability should be highlighted.[Conclusion] The research provided reference for establishment of a new management model for ecosystem adaptability to climate and sustainable development of grasslands in northern China.

Revisiting Sustainable Development of Dry Valleys in Hengduan Mountains Region

Dry valleys are a striking geographic landscape in Hengduan Mountains Region and are characterized by low rainfall, desert type of vegetation and fragile environment. Past efforts and resources have been concentrated mainly on rehabilitation of degraded ecosystem and fragile environment, particularly reforestation, while socio-economic development has been largely overlooked. Despite successes in pocket areas, the overall trend of unsustainability and environmental deterioration are continuing. It is important to understand that uplift of the Tibetan Plateau is the root cause of development of dry valleys, and development and formation of dry valleys is a natural process. Human intervention has played a secondary role in development of dry valleys and degradation of dry valleys though human intervention in many cases has speeded up environmental degradation of the dry valleys. It is important to understand that dry valleys are climatic enclaves and an integrated approach that combines rehabilitation of degraded ecosystems and socio-economic development should be adopted if the overall goal of sustainable development of dry valleys is to be achieved. Promotion of niche-based cash crops, rural energy including hydropower, solar energy, biogas and fuelwood plantation is recommended as the priority activities.

GLOBAL CLASSICAL SOLUTIONS TO QUASILINEAR HYPERBOLIC SYSTEMS WITH WEAK LINEAR DEGENERACY

Consider the following Cauchy problem for the first order quasilinear strictly hy- perbolic system ?u ?u + A(u) = 0, ?t ?x t = 0 : u = f(x). We let M = sup |f (x)| < +∞. x∈R The main result of this paper is that under the assumption that the system is weakly linearly degenerated, there exists a positive constant ε independent of M, such that the above Cauchy problem admits a unique global C1 solution u = u(t,x) for all t ∈ R, provided that +∞ |f (x)|dx ≤ ε, ?∞ +∞ ε |f(x)|dx ≤ . M∞

Driving mechanisms of nitrogen transport and transformation in lacustrine wetlands

As an essential component of proteins and genetic material for all organisms, nitrogen(N) is one of the major limiting factors that control the dynamics, biodiversity and functioning of lacustrine wetlands, in which intensified N biogeochemical activities take place. Reactive N loaded into wetland ecosystems has been doubled due to various human activities, including industrial, agricultural activities and urbanization. The main driving mechanisms of N transport and transformation in lacustrine wetlands are categorized to pushing forces and pulling forces in this study. Geomorphology, wetland age, N concentrations, and temperature are the main pushing forces(passive forces); whereas water table variation, oxygen concentration, other elements availability, oxidation-reduction potential(Eh) and p H, and microorganisms are the predominant pulling forces(active forces). The direction and kinetic energy of reactions are determined by pulling forces and then are stimulated by pushing forces. These two types of forces are analyzed and discussed separately. Based on the analysis of driving mechanisms, possible solutions to wetland N pollutions are proposed at individual, regional and global scales, respectively. Additional research needs are addressed to obtain a thorough understanding of N transport and transformations in wetlands and to reduce detrimental impacts of excessive N on such fragile ecosystems.