《系统动力学全英文版 期末考试汇总.doc》由会员分享，可在线阅读，更多相关《系统动力学全英文版 期末考试汇总.doc（16页珍藏版）》请在金锄头文库上搜索。
1、系统动力学全英文版 期末考试汇总 Final version of System Dynamic System Dynamic 郑春燕 Chapter 1: Introduction to System Dynamics 1. 1) Systems thinking 2) Personal mastery 3) Mental models 4) Building shared vision 5) Team learning 2. Mental models are the images (attitudes and assumptions) we carry in our minds abou
2、t ourselves, other people, institutions, and every aspect of the world which guide our interpretations and behavior. 3. The butterfly effect is the sensitive dependence on initial conditions in which a small change at one place in a deterministic nonlinear system can result in large differences in a
3、 later state. Chapter2: Systems and System Thinking 1.Modeling concepts A model is an abstraction of a real object or system. 2.A system is a set of two or more elements that satisfies the following three conditions: ? It fulfills a certain function ? The behavior of each element has an effect on th
4、e behavior of the whole ? The behavior of the elements and their effects on the whole are interdependent The behavior of a system depends not only on the behavior of the components of a system but also on how these components interact. 3. 1) Objects 2) States 3) Events 4) Time 5) Space 6)Structure 4
5、. “Complex systems” are systems in which there are multiple interactions between many different components (or agents).A complex system is characterized by multiple agents whose interactions give rise to structural effects that arent apparent in the agents themselves. Chapter 4: Structure and Behavi
6、or of Dynamic Systems 4.1 Fundamental modes of dynamic behavior The most fundamental modes of behavior are exponential growth, goal seeking, and oscillation. Each of these is generated by a simple feedback structure: positive feedback arises from negative feedback 1 Final version of System Dynamic a
7、rises from negative feedback with time delays in the loop. Other common modes of behavior, including S-shaped growth, S-shaped growth with overshoot and oscillation, and overshoot and collapse, arise from nonlinear interactions of the fundamental feedback structures. Exponential growth arises from p
8、ositive (self-reinforcing) feedback. The larger the quantity, the greater its net increase, further augmenting the quantity and leading to ever-faster growth. Pure exponential growth has the remarkable property that the doubling time is constant: the state of the system doubles in a fixed period of
9、time, no matter how large. In dynamic modeling, the term rate generally refers to the absolute rate of change in a quantity. The term birth rate here refers to the number of people born per time period. Often, however, the term rate is used as shorthand for the fractional rate of change of a variabl
10、e. For example, the birth rate is often interpreted as the number of births per year per thousand people. Similarly, we commonly speak of the unemployment rate. The word rate in these cases actually means ratio: the unemployment rate is the ratio of the number of unemployed workers to the labor forc
11、e ? The units of measure for rates of flow are units/time period. ? The units of measure for fractional rates of flow are units per unit per time period = 1/time periods. 2 Final version of System Dynamic Negative loops seek balance, equilibrium, and stasis. Negative feedback loops act to bring the
12、state of the system in line with a goal or desired state. When the relationship between the size of the gap and the corrective action is linear, the rate of adjustment is exactly proportional to the size of the gap and the resulting goal-seeking behavior is exponential decay. As the gap falls, so to
13、o does the adjustment rate. Every negative loop includes a process to compare the desired and actual conditions and take corrective action. Oscillation is the third fundamental mode of behavior observed in dynamic systems. Like goal-seeking behavior, oscillations are caused by negative feedback loop
14、s. In an oscillatory system, the state of the system constantly overshoots its goal or equilibrium state, reverses, then undershoots, and so on. The overshooting arises from the presence of significant time delays in the negative loop. The time delays cause corrective actions to continue even after
15、the state of the system reaches its goal, forcing the system to adjust too much, and triggering a new correction in the opposite direction Oscillations are among the most common modes of behavior in dynamic systems. Damped oscillations Limit cycles Chaos Oscillations can arise if there is a significant delay in any part of the negative loop. Perceiving the state of the system caused by the measurement and reporting system Initiating corrective actions after the discrepancy is perceived due to the time required to reach a decision. Delays between the initia
