1.Important General Principle: The information delivered by a feedback loop can only affect future behavior: it can't deliver the information, and so can't have an impact fast enough to correct behavior that drove the current feedback.
2.Every balancing feedback loop has its breakdown point.
3.Complex behaviors of systems often arise as the relative strengths of feedback loops shift, causing first one loop and then another to dominate behavior.
4.Shifting dominance refers to the change in dominance between inflows and outflows.
5.Model utility depends not on whether its driving scenarios are realistic but on whether it responds with a realistic pattern of behavior.
1.Questions for testing the value of a model
1. are the driving factors likely to unfold this way?
2. If they did would the system react this way?
3. What is driving the driving factors?2.Systems with similar feedback structures produce similar dynamic behaviors
3.A delay in a balancing feedback loop makes a system likely to oscillate.
4.Any physical, growing system is going to run into some kind of constraint sooner or later.
5.A quantity growing exponentially toward a constraint or limit reaches that limit in a surprisingly short time.
1. How does one identify out of a system what are the reinforcing, feedback and balancing loops? Guesswork?
2. How is one able to predict future patterns if the variables are always changing?
Tuesday, January 31, 2012
Meadows Chapter 2: A Brief Visit to the Systems Zoo
One Stock Systems:
A thermostat is an example of a stock with two competing balancing loops.
-In this example the heating loop dominates the cooling loop.
Competing Balancing loops often result in feedback loops.
Important General Principle: The information delivered by a feedback loop can only affect future behavior: it can't deliver the information, and so can't have an impact fast enough to correct behavior that drove the current feedback.
There will always be delays in responding.
A stock-maintaining balancing feedback loop must have its goal set appropriately to compensate for draining or inflowing processes that affect that stock. Otherwise the feedback process will fall short of or exceed the target stock.
Every balancing feedback loop has its breakdown point.
Whenever the inflow rate falls behind the outflow rate, the temperature falls.
Shifting dominance refers to the change in dominance between inflows and outflows.
Complex behaviors of systems often arise as the relative strengths of feedback loops shift, causing first one loop and then another to dominate behavior.
Questions for testing the value of a model
1. are the driving factors likely to unfold this way?
2. If they did would the system react this way?
3. What is driving the driving factors?
Model utility depends not on whether its driving scenarios are realistic but on whether it responds with a realistic pattern of behavior.
Systems with similar feedback structures produce similar dynamic behaviors
A delay in a balancing feedback loop makes a system likely to oscillate.
Delays are pervasive in systems and they are strong determinants of behavior. Changing the length of a delay and the relative lengths of other delays make a large change in the behavior of a system.
Two Stock Systems
Any physical, growing system is going to run into some kind of constraint sooner or later.
In physical, exponentially growing systems there must be at least one reinforcing loop driving the growth, because no physical system can grow forever in a finite environment.
The limits on a growing system can be temporary or permanent.
A quantity growing exponentially toward a constraint or limit reaches that limit in a surprisingly short time.
Nonrenewable resources are stock-limited. The entire stock is available at once at can be extracted at any rate. But since the stock is not renewed the faster the extraction rate, the short the lifetime of the resource.
Renewable resources are flow-limited. They can support extraction or harvest indefinitely, but only at a finite flow rate equal to their regeneration rate. If they are extracted faster than they regenerate, they may eventually be driven below a critical threshold and become for all practical purposes nonrenewable.
This chapter was ultimately confusing for me! I have trouble seeing the charts and graphs literally which makes it difficult for me to understand.
A thermostat is an example of a stock with two competing balancing loops.
-In this example the heating loop dominates the cooling loop.
Competing Balancing loops often result in feedback loops.
Important General Principle: The information delivered by a feedback loop can only affect future behavior: it can't deliver the information, and so can't have an impact fast enough to correct behavior that drove the current feedback.
There will always be delays in responding.
A stock-maintaining balancing feedback loop must have its goal set appropriately to compensate for draining or inflowing processes that affect that stock. Otherwise the feedback process will fall short of or exceed the target stock.
Every balancing feedback loop has its breakdown point.
Whenever the inflow rate falls behind the outflow rate, the temperature falls.
Shifting dominance refers to the change in dominance between inflows and outflows.
Complex behaviors of systems often arise as the relative strengths of feedback loops shift, causing first one loop and then another to dominate behavior.
Questions for testing the value of a model
1. are the driving factors likely to unfold this way?
2. If they did would the system react this way?
3. What is driving the driving factors?
Model utility depends not on whether its driving scenarios are realistic but on whether it responds with a realistic pattern of behavior.
Systems with similar feedback structures produce similar dynamic behaviors
A delay in a balancing feedback loop makes a system likely to oscillate.
Delays are pervasive in systems and they are strong determinants of behavior. Changing the length of a delay and the relative lengths of other delays make a large change in the behavior of a system.
Two Stock Systems
Any physical, growing system is going to run into some kind of constraint sooner or later.
In physical, exponentially growing systems there must be at least one reinforcing loop driving the growth, because no physical system can grow forever in a finite environment.
The limits on a growing system can be temporary or permanent.
A quantity growing exponentially toward a constraint or limit reaches that limit in a surprisingly short time.
Nonrenewable resources are stock-limited. The entire stock is available at once at can be extracted at any rate. But since the stock is not renewed the faster the extraction rate, the short the lifetime of the resource.
Renewable resources are flow-limited. They can support extraction or harvest indefinitely, but only at a finite flow rate equal to their regeneration rate. If they are extracted faster than they regenerate, they may eventually be driven below a critical threshold and become for all practical purposes nonrenewable.
This chapter was ultimately confusing for me! I have trouble seeing the charts and graphs literally which makes it difficult for me to understand.
Chapter 1 5 Factoids
Just noticed I forgot to include 5 facts about chapter one in my 552!
1.The most important part of a system is the relationships between elements.
2.Although stocks get left out they are extremely important!!
3.Systems can be found everywhere!
4.The feedback loop connects different parts of the system.
5.The word function is used for a nonhuman system whereas purpose is used for a human system
1.The most important part of a system is the relationships between elements.
2.Although stocks get left out they are extremely important!!
3.Systems can be found everywhere!
4.The feedback loop connects different parts of the system.
5.The word function is used for a nonhuman system whereas purpose is used for a human system
Friday, January 27, 2012
Chapter 1 (552)
1. I found it interesting how truly obvious a system is. I thought it would be more complicated but I found that I was noticing systems all around my room as i was reading the chapter.
2. The idea that the elements of a system can change almost seamlessly without changing the purpose of a system. It seemed like the elements were an integral part and with them changing it would make the system different but I now understand that the main function of the system wouldn't be changed with the elements, this idea made complete sense to me after the football team analogy.
3. Meadows talked about changing the outflow to increase the inflow. I thought this was a really cool idea, with the bathwater example it made so much sense that increasing the inflow was not the only way to fill the tub faster but also to decrease the outflow. Another example which was really helpful was the idea of instead of hiring more people to increase business size, merely decrease firing and quitting rates.
4. My favorite part of this chapter was the question at the last page that said "if A causes B, isn't it possible that B causes A." I thought that was a really good way to end the chapter it got me thinking and questioning if that was possible.
5. My last interesting fact from the chapter is that not all systems need interference to balance themselves out, some of the balancing occurs on its own. I thought that was a really cool idea that nature tends to balance itself.
Questions:
1. Why do people tend to focus more on stocks? If they are concerned with the input or output wouldn't it make sense to focus on that instead of just the stock?
2. What if B could cause A? How would that affect a system if an result caused an action?
Meadows Chapter 1: The Basics
What is a system? Its an interconnected set of elements that is coherently organized in a way that achieves something.
The system must include:
The system must include:
- elements
- interconnectedness
- a function or purpose
EVERYTHING HAS A SYSTEM!
However, without the interconnectedness or function there is no system. Determining the relationships are more important than defining all the elements. Many interconnections are the flow of information. The elements of a system can be easily changed without harm to the system yet when the interconnections are altered, so is the system.
Stocks are the foundations of systems, the elements you can see, feel count or measure at any given time. Stocks change over time due to flows, a stock is a present memory of the history of changing flows within the system.
The dynamics of stocks and flows is the behavior over. This helps us learn more about the stocks and flow and how they change. When the level of inflow to outflow does not change, it is called dynamic equilibrium.
"Stocks take time to change because flows take time to flow"
Feedback loop: a feedback loop is formed when changes in stock affect the flows into or out of that same stock. The feedback loop needs to be stabilized. Feedback loops can also often operate in two directions. Feedback loops can be stabilized with a balancing Feedback loop, these are goal-seeking or stability-seeking. The other type of feedback loop is called a reinforcing feedback loop, this is described as an amplifying, reinforcing and self-multiplying force. This generates more input to a stock the more that is already there.
That's it for today! That chapter really made me understand quickly what a system is and its real purpose, the loops were slightly confusing but hopefully after next class it'll make more sense.
What is the Scientific Method?
The scientific method differs largely from other ways of knowing in that it focuses mainly on observation and experimentation. Many ways of gaining knowledge come from sources such as books, authority figures (government, church, teachers, parents etc.). The scientific method however, allows one to make that jump to conclusion by oneself, through their experiments. For instance, if one was noticed that college students tend to sleep more than other age groups, there would be two different directions to go about finding out why. The most obvious answer, and definitely the easiest would be to ask someone, a teacher or even an online source (as many of us resort to google for everyday questions) which would give us a fact yet the validity of that fact is questionable. The other approach would be to conduct an experiment, surveying different age groups, their stressors, and their amount of sleep. AN experiment such as this would help to determine if the sleep levels are caused by the stress of being in college or merely needing more sleep at that age.
The scientific method is truly a way for one to see the data laid out in front of them which would allow them to come to an educated guess which they have seen the results of, as opposed to getting information second-hand and accepting it as fact.
Welcome!
Hello readers,
Welcome to my notebook blog for Patterns in Nature. This blog will follow my experience of this class from start to finish, including notes, project ideas, and reflections of class. I hope to include pictures and videos as well to enhance the experience of this read. Hope you enjoy!
Welcome to my notebook blog for Patterns in Nature. This blog will follow my experience of this class from start to finish, including notes, project ideas, and reflections of class. I hope to include pictures and videos as well to enhance the experience of this read. Hope you enjoy!
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