463
个编辑
更改
→Topics in systems dynamics
系统动力学的第一个非公司领域的应用出现之后，紧随其后出现了第二个主要的非公司应用。1970年，Jay Forrester 应罗马俱乐部的邀请参加了在瑞士伯尔尼举行的一次会议。罗马俱乐部是一个致力于解决其成员所描述的”人类困境”的组织，即今后某个时候可能出现的全球危机，因为世界人口呈指数增长，对地球的承载能力（可再生和不可再生资源的来源及其处理污染物的汇）提出了要求。在伯尔尼会议上，Forrester 被问及是否可以用系统动力学来解决人类的困境。当然，他的回答是可以。在从伯尔尼会议回来的飞机上，弗雷斯特创建了世界社会经济系统系统动力学模型的初稿。他把这个模型叫做 WORLD1。回到美国后，弗雷斯特精炼了 WORLD1，为罗马俱乐部成员访问麻省理工学院做准备。称这个模型为 WORLD2的改进版本。在一本名为《世界动力学》的书中出版了 WORLD2。
系统动力学的第一个非公司领域的应用出现之后，紧随其后出现了第二个主要的非公司应用。1970年，Jay Forrester 应罗马俱乐部的邀请参加了在瑞士伯尔尼举行的一次会议。罗马俱乐部是一个致力于解决其成员所描述的”人类困境”的组织，即今后某个时候可能出现的全球危机，因为世界人口呈指数增长，对地球的承载能力（可再生和不可再生资源的来源及其处理污染物的汇）提出了要求。在伯尔尼会议上，Forrester 被问及是否可以用系统动力学来解决人类的困境。当然，他的回答是可以。在从伯尔尼会议回来的飞机上，弗雷斯特创建了世界社会经济系统系统动力学模型的初稿。他把这个模型叫做 WORLD1。回到美国后，弗雷斯特精炼了 WORLD1，为罗马俱乐部成员访问麻省理工学院做准备。称这个模型为 WORLD2的改进版本。在一本名为《世界动力学》的书中出版了 WORLD2。
==Topics in systems dynamics==
==系统动力学主题 Topics in systems dynamics==
The elements of system dynamics diagrams are feedback, accumulation of flows into stocks and time delays.
The elements of system dynamics diagrams are feedback, accumulation of flows into stocks and time delays.
The elements of system dynamics diagrams are feedback, accumulation of flows into stocks and time delays.
The elements of system dynamics diagrams are feedback, accumulation of flows into stocks and time delays.
系统动力学图的要素包括反馈、流到库存的累积和时间延迟。
As an illustration of the use of system dynamics, imagine an organisation that plans to introduce an innovative new durable consumer product. The organisation needs to understand the possible market dynamics in order to design marketing and production plans.
As an illustration of the use of system dynamics, imagine an organisation that plans to introduce an innovative new durable consumer product. The organisation needs to understand the possible market dynamics in order to design marketing and production plans.
作为系统动力学应用的一个例子，设想一个组织计划引入一种创新的耐用消费品。组织需要了解可能的市场动态，以便设计营销和生产计划。
===因果循环图 Causal loop diagrams===
===Causal loop diagrams===
{{Main article|Causal loop diagram}}
{{Main article|Causal loop diagram}}
===Stock and flow diagrams===
===库存和流程图 Stock and flow diagrams===
这里Stock有文献描述为流位变量，具体翻译成什么内容有待考虑，下同
{{Main article|Stock and flow}}
{{Main article|Stock and flow}}
===Equations===
===方程式 Equations===
The real power of system dynamics is utilised through simulation. Although it is possible to perform the modeling in a [[spreadsheet]], there are a [[Comparison of system dynamics software|variety of software]] packages that have been optimised for this.
The real power of system dynamics is utilised through simulation. Although it is possible to perform the modeling in a [[spreadsheet]], there are a [[Comparison of system dynamics software|variety of software]] packages that have been optimised for this.
通过仿真实现了系统动力学的真正威力。尽管在电子表格中执行建模是可能的，但是已经为此优化了各种软件包。
通过仿真实现了系统动力学的真正威力。尽管在电子表格中执行建模是可能的，但是已经为此优化了各种软件包。
*Define the problem boundary 定义问题边界
*Identify the most important stocks and flows that change these stock levels 确定改变这些库存水平的最重要的库存和流量
*Identify sources of information that impact the flows 确定影响信息流的信息来源
*Identify the main feedback loops 确定主要反馈回路
*Draw a causal loop diagram that links the stocks, flows and sources of information 绘制一个因果循环图，将库存、流量和信息来源联系起来
*Write the equations that determine the flows 写出确定流量的方程式
*Estimate the parameters and initial conditions. These can be estimated using statistical methods, expert opinion, market research data or other relevant sources of information. 估计参数和初始条件。这些可以使用统计方法、专家意见、市场研究数据或其他相关信息来源进行估计。
*Estimate the parameters and initial conditions. These can be estimated using statistical methods, expert opinion, market research data or other relevant sources of information.<ref name="Sterman2001CMR">{{cite journal |last=Sterman |first=John D. |year=2001 |title=System dynamics modeling: Tools for learning in a complex world |journal=California Management Review |volume=43 |issue=4 |pages=8–25|doi=10.2307/41166098 |jstor=41166098 }}</ref>
<ref name="Sterman2001CMR">{{cite journal |last=Sterman |first=John D. |year=2001 |title=System dynamics modeling: Tools for learning in a complex world 系统动力学建模：在复杂世界中学习的工具 |journal=California Management Review 加州管理评论 |volume=43 |issue=4 |pages=8–25|doi=10.2307/41166098 |jstor=41166098 }}</ref>
*Simulate the model and analyse results. 对模型进行仿真分析。
===Equations in discrete time===
===离散时间方程 Equations in discrete time===
List of all the equations in [[discrete time]], in their order of execution in each year, for years 1 to 15 :
List of all the equations in [[discrete time]], in their order of execution in each year, for years 1 to 15 :
====Dynamic simulation results====
====动态模拟结果 Dynamic simulation results====
The dynamic simulation results show that the behaviour of the system would be to have growth in ''adopters'' that follows a classic s-curve shape.<br />
The dynamic simulation results show that the behaviour of the system would be to have growth in ''adopters'' that follows a classic s-curve shape.<br />
[[Image:Adoption SFD ANI.gif|centre|Dynamic stock and flow diagram of ''New product adoption'' model|frame]]
[[Image:Adoption SFD ANI.gif|centre|Dynamic stock and flow diagram of ''New product adoption'' model “新产品采用”模型的动态库存和流程图|frame]]
frame
frame
框架
框架
[[Image:SFDD VAL.gif|centre|Stocks and flows values for years = 0 to 15|frame]]
[[Image:SFDD VAL.gif|centre|Stocks and flows values for years = 0 to 15 年存量和流量值=0至15|frame]]
frame
frame
===Equations in continuous time===
===连续时间方程 Equations in continuous time===
To get intermediate values and better accuracy, the model can run in continuous time: we multiply the number of units of time and we proportionally divide values that change stock levels. In this example we multiply the 15 years by 4 to obtain 60 trimesters, and we divide the value of the flow by 4.<br>
To get intermediate values and better accuracy, the model can run in continuous time: we multiply the number of units of time and we proportionally divide values that change stock levels. In this example we multiply the 15 years by 4 to obtain 60 trimesters, and we divide the value of the flow by 4.<br>
用欧拉法除值是最简单的方法，但也可以用其他方法代替，如龙格-库塔法。
用欧拉法除值是最简单的方法，但也可以用其他方法代替，如龙格-库塔法。
框架
框架
==Application==
==Application==