基于Petri网的仿真研究

介绍了Petri网的主要分析方法,概述了Petri网的发展历程及研究现状,分析了Petri网仿真研究方法。     

基于Daubechies4小波变换地形滤波的复杂电磁环境仿真加速方法

本文提出了一种基于射线追踪算法的复杂电磁环境仿真计算的加速方法,同时结合并行系统来共同加速仿真计算。对地形DEM数据进行Daubechies4二维离散小波变换,地形滤波在一定范围内有效降低了其复杂度。继而搭建并行计算系统,将滤波后的地形应用到多个辐射源的仿真建模并行计算,提高复杂电磁环境仿真计算速度。经过对该方法进行多次实验,验证了该方法可以在一定精度范围内提高复杂电磁环境计算速度。     

基于响应面法的机械可靠性设计与仿真方法研究

为研究机械结构可靠性设计与仿真方法。本文基于应力-强度干涉模型,应用响应面法(RSM),充分考虑结构分析中各参数的随机分布特性,利用ANSYS-PDS模块对法兰进行结构可靠性仿真。仿真结果显示,在进行10000次循环模拟计算后,法兰的结构可靠度为92.9%,灵敏度分析显示屈服极限与压力对可靠性影响最大。证明基于响应面法的可靠性分析方法为机械结构优化及可靠性计算提供指导,具有一定的工程应用价值。     

福建省经济系统物质流分析研究

运用物质流分析(MFA)方法,对福建省经济系统在1990~2008年间的物质输入与输出进行系统地分析,探讨了福建省经济发展与环境压力的关系。研究结果表明,福建省"资源高投入"的粗放型经济发展模式没有实现根本转变。主要结论有:(1)福建省物质输入量不断上升,能源需求急剧增长;(2)隐藏流不断增加,矿产资源地生态包袱不断增大;(3)区域过程排放缓慢上升,大气污染物排放为主要推动因子;(4)物质需求强度有反弹趋势,经济发展与物质需求出现扩张性"复钩"。最后,对福建省经济可持续发展提出了大力提高资源能源利用率、推进循环经济发展、优化产业结构、继续强化环境综合整治等建议。     

养殖业和种植业相互关系的探讨

前言农业生产系统的功能,实质上是农业资源的利用效率。农业资源产生的物质流、能量流、实物流和价值,按照一定的规律,通过农业生态、技术、经济这三个主要子系统进行循环。农业生产系统的结构是其功能的基础,不同的结构具有不同的功能。我们对个体农民基本情况的调查和实地实验测定,证明农业生产中的养殖业和种植业,是互为条     

产业共生网络演化研究进展

产业共生网络是通过物料、能源或信息等的传递所形成的企业间复杂的合作共生关系网络。由于受各种内外部因素的影响,产业共生网络一直处于不断发展演变中。研究产业共生网络演化,对破解工业园区资源与环境瓶颈、推动园区可持续发展具有重要的意义。我国工业园区经过数十年的快速发展,已初步形成了基于园区尺度的产业共生网络。本文对产业共生网络的形成及发展现状进行总结,分析了产业共生网络演化的驱动力及影响因素,并对现有的产业共生网络研究方法进行综述,对比与评价了不同建模方法的建模思路及优劣势。基于此,提出了未来研究与实践中需要突破的关键问题,建议继续拓展产业共生的研究范围,加强对产业共生网络演化仿真及可持续性评估的研究,从而为工业园区规划与管理提供可预测的、量化的指导工具。     

基于仿真实验的导轨结合面刚度建模方法研究

以分形理论和分形理论与域扩展因子为基础,设计了四种导轨动态接触刚度的理论计算模型,并将结果分别应用于仿真分析中,获得了四种不同方案下的有限元仿真分析结果;设计搭建了一种仅含导轨结合面的实验平台,并进行了模态试验;通过各方案仿真分析结果与实验的比较,获得了导轨结合面刚度建模方法的最优方案。     

旅游流研究进展与启示

梳理了国内外关于旅游流的相关研究成果。结果表明:(1)理论与方法上,主要是依据旅游系统理论、流空间理论、关系经济地理学理论、空间结构理论、社会网络理论和旅游动机理论。同时,一些复杂的空间计量统计模型、社会网络分析方法、系统仿真模型等应用较多。(2)研究内容上,对旅游流时空分布特征、网络结构特征、影响因素、驱动机制、流动效应和空间网络6个方面的有关主题进行了系统研究。(3)实证研究上,重点关注全国尺度范围内、典型区域之间、重要省域、城市之间和微观景区内部游客流动的特征与规律。     

入境旅游流“驱动力—状态—响应”模型构建

借鉴国内外旅游流相关评价指标体系,基于中国旅游六大典型城市的统计数据,利用因子分析与系统动力学分析方法探讨了客源地驱动力、入境旅游流状态与目的地城市响应的模型。研究发现:1所构建的客源地驱动力、旅游流状态与目的地响应指标体系由3个目标层、13个准则层、43个指标构成。2构建了"驱动力—状态—响应"概念模型,具有很强的理论吻合性。3将入境旅游流与客源地驱动力系统、经济社会子系统、资源区位子系统、服务设施子系统和信息技术子系统逐一对应,构建整体动力系统因果回路图,研究体量匹配并对旅游与城市建设问题进行了探讨。     

基于主体的建模方法在环境学科中的研究进展

基于主体的建模方法(ABM)通过自下而上的仿真模拟,考察系统中微观层面异质性主体的状态和行为特征、主体之间的交互、主体与环境的作用,来表征系统宏观现象的涌现,是进行复杂系统模拟和政策评价的重要工具。本文在大量文献调研的基础上,总结了ABM在水文领域、土地资源管理、大气污染防治及环境政策评价等方面的研究进展,归纳了其在主体设计、交互关系与规则、系统环境特征等建模范式方面的共性,论述了该方法对环境系统建模分析的重要意义。     

泰勒杆试验的动态本构模型确认应用研究

本文运用模型确认理论,对泰勒杆试验在材料动态本构关系确认性方面的应用进行研究。以Johnson-Cook模型描述的OFHC材料为例,采用试验和数值模拟相比较迭代的优化方法,结合灵敏度分析,提出了一种简捷的确认和确定动态本构关系参数的方法。     

Modeling flood induced interdependencies among hydroelectricity generating infrastructures

This paper presents a new kind of integrated modeling method for simulating the vulnerability of a critical infrastructure for a hazard and the subsequent interdependencies among the interconnected infrastructures. The developed method has been applied to a case study of a network of hydroelectricity generating infrastructures, e.g., water storage concrete gravity dam, penstock, power plant and transformer substation. The modeling approach is based on the fragility curves development with Monte Carlo simulation based structural–hydraulic modeling, flood frequency analysis, stochastic Petri net (SPN) modeling, and Markov Chain analysis. A certain flood level probability can be predicted from flood frequency analysis, and the most probable damage condition for this hazard can be simulated from the developed fragility curves of the dam. Consequently, the resulting interactions among the adjacent infrastructures can be quantified with SPN analysis; corresponding Markov Chain analysis simulates the long term probability matrix of infrastructure failures. The obtained results are quite convincing to prove the novel contribution of this research to the field of infrastructure interdependency analysis which might serve as a decision making tool for flood related emergency response and management.     

Industrial metabolism of PVC in China: A dynamic material flow analysis

In China, the rapid development of the polyvinylchloride (PVC) industry will inevitably lead to various environmental problems. This paper studies the PVC metabolism further by (1) constructing dynamic models based on material flow analysis (MFA), (2) introducing calculation on detailed lifetime distribution of different types of products and recycling, and (3) obtaining the performances of waste emissions and accumulation as a function of raw material input and time. Based on system evolution theory and population development models, the developing trend of the PVC industry is studied, and annual consumptions in future years are predicted. The annual emission and accumulation after metabolism can be calculated by tracking the amount of raw material input, existing form and process flow for a single year (2003), as well as over a longer period (from 1958 to 2048) in China. Analysis indicates that over 0.6 billion tons of PVC waste will have accumulated in the environment by the end of 2050. In this scenario analysis, the effects of product structure, lifetime distribution, mechanical recycling, chemical recycling and incineration on waste output are all taken into consideration. The product metabolism process can be decelerated by changing these factors appropriately. However, mechanical recycling and chemical recycling are the most effective solutions.     

Uncertainty Analysis In Dissolved Oxygen Modeling in Streams

Uncertainty analysis in surface water quality modeling is an important issue. This paper presents a method based on the first-order reliability method (FORM) to assess the exceedance probability of a target dissolved oxygen concentration in a stream, using a Streeter–Phelps prototype model. Basic uncertainty in the input parameters is considered by representing them as random variables with prescribed probability distributions. Results obtained from FORM analysis compared well with those of the Monte Carlo simulation method. The analysis also presents the stochastic sensitivity of the probabilistic outcome in the form of uncertainty importance factors, and shows how they change with changing simulation time. Furthermore, a parametric sensitivity analysis was conducted to show the effect of selection of different probability distribution functions for the three most important parameters on the design point, exceedance probability, and importance factors. Note: This version was published online in June 2005 with the cover date of August 2004.     

基于薄弱环节的发动机加速贮存试验研究

对基于薄弱环节的发动机加速贮存试验的理论依据和发动机加速贮存试验的基本流程进行了介绍,在对发动机薄弱环节的确定方法和薄弱环节失效机理分析的基础上,提出了材料、部组件和整机层层递进的加速贮存试验方案和基于物理老化、化学老化和使用载荷验证的发动机加速贮存试验一体化设计方法.     

HYDROLOGIC MODELING USING A SIMULATION LANGUAGE BASED ON QUEUEING THEORY1

ABSTRACT: A novel approach has been developed by applying queueing theory to hydrologic modeling. A queueing situation is characterized by a flow of customers arriving randomly at one or more service facilities. In this case, the customers are represented by water and the service time is the time it takes to move through the soil and over the land. This approach has the potential to be simpler and more efficient than some previously developed models. Another important attribute of queueing theory is its ability to model almost unlimited detail. Many simulation languages based on queueing theory have been developed and tested and are available. Applications of the languages include manufacturing operations, transportation systems, computer systems, financial planning, and health care systems. A model was developed, using a simulation language, to predict runoff hydrographs from storms occurring on small homogeneous watersheds. With continued development, queueing theory could provide an effident, detailed approach to simulating many natural processes.     

SPATIAL MODELLING WITH GEOGRAPHIC INFORMATION SYSTEMS FOR DETERMINATION OF WATER RESOURCES VULNERABILITY APPLICATION TO AN AREA IN MASSIF CENTRAL (FRANCE)1

ABSTRACT: A method for water resources protection based on spatial variability of vulnerability is proposed. The vulnerability of a water resource is defined as the risk that the resource will become contaminated if a pollutant is placed on the surface at one point as compared to another. A spatial modelling method is defined in this paper to estimate a travel time between any point of a catchment and a resource (river or well). This method is based on spatial analysis tools integrated in Geographical Information Systems (GIS). The method is illustrated by an application to an area of Massif Central (France) where three different types of flow appear: surface flow, shallow subsurface flow, and permanent ground water flow (baseflow). The proposed method gives results similar to classical methods of estimation of travel time. The contribution of GIS is to improve the mapping of vulnerability by taking the spatial variability of physical phenomena into account.     

An approach to optimise nutrient management in environmental sanitation systems despite limited data

The material flow analysis method can be used to assess the impact of environmental sanitation systems on resource consumption and environmental pollution. However, given the limited access to reliable data, application of this data-intensive method in developing countries may be difficult. This paper presents an approach allowing to develop material flow models despite limited data availability. Application of an iterative procedure is of key importance: model parameter values should first be assessed on the basis of a literature review and by eliciting expert judgement. If model outputs are not plausible, sensitive input parameters should be reassessed more accurately. Moreover, model parameters can be expressed as probability distributions and variable uncertainty estimated by using Monte Carlo simulation. The impact of environmental sanitation systems on the phosphorus load discharged into surface water in Hanoi, Vietnam, is simulated by applying the proposed approach.     

经济—环境系统物质流分析——以四川某地区为例

本文运用物质流计算理论与方法,以四川省某市的一个行政区为例,计算并分析了其2004年至2007年具体物质代谢过程。结果表明:随着城市化水平提高和国民经济的发展,其对外资源的依赖程度不断增加,物质消耗强度趋向全国平均水平,资源利用效率同全国其他地方一样有所提高,但经济发展模式还没有实现根本转变。     

An ecological perspective on theory, methods, and analysis in environmental psychology: Advances and challenges

Over the course of environmental psychology's brief history, there has been an interest in ecologically oriented approaches to theory and research. Based on this work, this paper identifies a set of six principles of ecological analysis that present theoretical, methodological, and analytic challenges to future research in environmental psychology. These challenges include the theoretical treatment of the multiple contexts within which human experience and behavior occurs, the need for sampling both persons and environments, the modeling of moderating and mediating processes, the issue of self-selection into and out of different settings, the necessity of considering temporal factors in environmental research, reliance on single methods (e.g., verbal report) in data generation, cross-sectional and longitudinal research designs, and the need for greater use of statistical techniques developed for contextual (multi-level) research. These issues are discussed and illustrated using recent developments in environmentally oriented research. The paper concludes with a set of 11 recommendations for the future.