Friday, 23 November 2012

STELLA Report



Teaching and Learning with Simulation and Modelling
The process of creating a model of an existing or proposed system in order to identify and understand those factors which control the system and/or to predict (forecast) the future behavior of the system is defined as simulation. The use of simulation able to educate and provide students for exploring the interesting and implication in teaching and learning. Simulation is something that can be played either in clinical education, training or for experimenting. More practically, simulation can be used to predict (forecast) the future behavior of a system, and determine what you can do to influence that future behavior. Simulation can be used to predict the way in which the system will evolve and respond to its surroundings, so that you can identify any necessary changes that will help make the system perform the way that you want it to. Simulation is a powerful and important tool because it provides a way in which alternative designs, plans and/or policies can be evaluated without having to experiment on a real system, which may be prohibitively costly, time-consuming, or simply impractical to do.
Modelling is a building representations of things in the ‘real world’ and allowing ideas to be investigated. It is central to all activities in the process for building or creating an artefact of some form or other. In effect, a model is a way of expressing a particular view of an identifiable system of some kind. Models are a means of understanding the problems involved in building something, a component of the methods used in development activities such as the analysis of the requirements for an artefact and the design of the artefact.
A model is an abstraction, which allows people to concentrate on the essentials of a (complex) problem by keeping out non-essential details. Since there is a limit to how much a person can understand at any one time, we build models to help in activities such as the development of large software systems. For example, developers build different models throughout the development process in order to verify that the eventual software system will meet the requirements.


Predator-Prey Relationship
Introduction
A predator is an organism that eats another organism. The prey is the organism which the predator eats. Predator and prey evolve together. The prey is part of the predator’s environment, and the predator dies if it does not fit in terms getting for food, so it evolves whatever is necessary in order to eat the prey; speed, stealth, camouflage (to hide while approaching the prey), a good sense of smeel, sight, or hearing (to find the prey), immunity to the prey’s poison, poison (to kill the prey) the right kind of mouth parts or digestive system. Besides, the predator is part of the prey’s environment and the prey dies if it is eaten by the predator, so it evolves whatever is necessary to avoid being eaten; speed, camouflage (to hide from the predator), a good sense of smell, sight, or hearing (to detect the predator), thorns, and poison (to spray when approached or bitten).
The fastest predators are able to catch food and eat, so that they can survive and reproduce and gradually faster predators make up more and more of the population. It same goes to the preys, which are fastest able to escape the predator, so they will survive and reproduce and gradually the faster preys make up more and more of the population. An important thing to be realized is that as both organisms become faster to adapt to their environments, their relationship remains the same because they are both getting faster, neither gets faster in relation to the other. This is the truly proof in all predation relationships. Other than that, the predator-prey relationship are usually used as a building blocks for an ecosystem. Predators hunt there prey and the preys population goes down until the population gets small enough in size to where the predators do not have enough prey to be hunted. The population starts to drive down because of there is not enough food for them. Furthermore, the preys start to grow bigger and they just keep going back and forth till some where down the line in the populations level off.
As in the Earth’s vast ecosystem, everything contains myraid parings of predators and their preys are connected by the food chain. For example lynx as the predator and the hares being as the prey. The daunting task of studying, describing and predicting the future of any one link in the chain and identifying its impact on the whole. Therefore, the predator-prey relationship can be distilled down to controlable chunks with the predator-prey model.

Figure 1
To run this simulation, first of all teacher needs to adjust the meter knob above to a desire number of lynx harvest. For examples in this picture, the number of lynx harvest for hares is 0, thus student will do their prediction on what type of graph line that will produce. So as we know, if there is no harvesting number of hares means no predation relationship between lynx and hares.
As refer to this figure 1, there is an interaction between the lynx as the predator and the hares as the prey in particular area. This simple predator-prey dynamics experiment is carried out over a several years time. The above graph shows there is no interaction between the predator and prey in an Earth ecosystem. Here, I assume that there is no population number of preys in the particular area because of the lacking sources of food for them to survive well. This condition will affects on the productivity of the predators hunting for a long lifetime. There are many factors that influence the availability source of food for the prey such as abiotic (non-living) components like weather, water supply, sunlight, minerals available, disease and also altitude. One of the reasons why the preys (hares) won’t be able to survive or adapt to the environment is maybe lack of sunlight for the crops to alive during winter season,thus this will affect the populations of the hares and lynx simultaneously. The crops are not be able to survive greatly during the winter season. That is why the graph shows there is no interaction between the lynx and hares for a several years lifetime.
The other logic reasons why the number of the predators become constant is maybe because of they are in hibernation states. The climate during this particular time is winter season thus; the lynx is kept in hibernating. Both of these organisms; the predators and preys faced the same limiting factor to overcome the interaction between them to occur. In this ecosystem, the predator-prey relationship become stable because no interaction between them. The predator and prey regulate the population of each other in a cyclical manner which maintains the populations of both organisms in a dynamic equilibrium. The winter season also contributes to the no interaction between the predator and prey because of the lack of food sources for both of them.
Both of them are really not adapt with the winter environment, automatically make them to live in a constant of population size simultaneously without any predator-prey interaction. The prey will survive peacefully without the disturbance from the predator hunting greedily. The predator also unable to hunt for food source because of the less or small number of prey population. The population sizes for both organisms for 0 until 60 years are just the same without changing any.

  
Figure 2
For the next step is teacher needs to adjust the meter knob above to a desire number of lynx harvest. For examples in this picture, the number of lynx harvest for hares is 210, thus student will do their prediction on what type of graph line that will produce. The lynx and hares start to interact each other but not really happen in this stage.
To survive and reproduce, individuals must obtain sufficient food sources while simultaneously avoiding becoming food for a predator. Figure 2 above shown the different pattern of predator-prey dynamic graphical compare to the Figure 1 previously. Here the lynx –hares study demonstrates the role of both predator avoidance and food availability on population sizes. The trade-off between food intake and the predator avoidance is not easily addressed in the field, and the ecologists have turned to mathematical models to better understand foraging behavior and predator-prey dynamics, just the same as economists and atmospheric scientists do.
In my opinion, both of these organisms are still practicing to adapt with the newly spring season henceforth the summer season. As the graph state above, both of them are still not in interaction each other because of the adaptation needs. The lynx is slowly increased in size same goes to the hares. After they achieve the comfort state, the prey has attracted the attention of the predator for hunting food for survival. Here I have adjusted the size of 1 time lynx harvest for the hares to 210. The number of lynx is changing over the several years depends on the population size of the hares. As the predator population is smaller than the prey population, and lags behind the prey population. In favorable conditions, when there are sufficient resources, an increase in the prey population is closely followed by an increase in the predator population.
However, when the prey population decreases as a result of increasing predation or the other factors such as the spread diseases, the predator’s food supply becomes limited and this leads to a declined in the population of predators. I do found the mechanism which controls the prey and predator size populations. First of all, I do notice that the level at which the prey population starts to fluctuate. The fluctuation of the prey wills leads either to an increasing in the size of the prey population or to a falling in the prey population. If the prey population is increase, the number of predator is increases also. This interaction wills a result to a declining in the prey population indirectly that returns the prey population to the level at which it fluctuates. In the other side, when the prey population is decline, resulting to decreases in the predator size population. Due to this condition, the prey population size is increase as well as the prey population has returns to the level at which it fluctuate primarily. Predator and prey populations cycle through time, as predators decrease the numbers of prey. Lack of food resources in turn decrease predator abundance, and the lack of predation pressure allow prey populations to rebound.

           
Figure 3
For this third simulation, teacher needs to adjust the meter knob above to a desire number of lynx harvest. In this picture, the number of lynx harvest for hares is 600, thus student will do their prediction that the graph must figured with a stiffness and declination lines to show the extreme predation occur.
Besides, the figure 3 shows the same graphical pattern as in figure 2 previously. But, here I have adjusted the size of 1 time lynx harvest for the hares slightly high to 600. The number of lynx is changing over the several years depends on the population size of the hares. As the predator population is smaller than the prey population, and lags behind the prey population. In favorable conditions, when there are sufficient resources, an increase in the prey population is closely followed by an increase in the predator population.
However, when the prey population decreases as a result of increasing predation or the other factors such as the spread diseases, the predator’s food supply becomes limited and this leads to a declined in the population of predators. I do found the mechanism which controls the prey and predator size populations. First of all, I do notice that the level at which the prey population starts to fluctuate. The fluctuation of the prey wills leads either to an increasing in the size of the prey population or to a falling in the prey population. If the prey population is increase, the number of predator is increases also. This interaction wills a result to a declining in the prey population indirectly that returns the prey population to the level at which it fluctuates. In the other side, when the prey population is decline, resulting to decreases in the predator size population. Due to this condition, the prey population size is increase as well as the prey population has returns to the level at which it fluctuate primarily. Predator and prey populations cycle through time, as predators decrease the numbers of prey. Lack of food resources in turn decrease predator abundance, and the lack of predation pressure allow prey populations to rebound.


Figure 4
Last but not least, teacher needs to adjust the meter knob above to a desire maximum number of lynx harvest. In this picture, the number of lynx harvest for hares is 750, thus student will do their prediction that the extreme predation occur will be more dangerous to the hares as the prey in this relationship. As the number predator increse, the number of prey will decline and vice verse.
In figure 4 shows the same graphical pattern as in figure 3 but differently it has a very stiff peak in every particular year. I have adjusted the size of 1 time lynx harvest for the hares to a very maximum number which is 750. The number of lynx is changing over the several years depends on the population size of the hares. As the predator population is smaller than the prey population, and lags behind the prey population. In favorable conditions, when there are sufficient resources, an increase in the prey population is closely followed by an increase in the predator population.
However, when the prey population decreases as a result of increasing predation or the other factors such as the spread diseases, the predator’s food supply becomes limited and this leads to a declined in the population of predators. I do found the mechanism which controls the prey and predator size populations. First of all, I do notice that the level at which the prey population starts to fluctuate. The fluctuation of the prey wills leads either to an increasing in the size of the prey population or to a falling in the prey population. If the prey population is increase, the number of predator is increases also. This interaction wills a result to a declining in the prey population indirectly that returns the prey population to the level at which it fluctuates. In the other side, when the prey population is decline, resulting to decreases in the predator size population. Due to this condition, the prey population size is increase as well as the prey population has returns to the level at which it fluctuate primarily. Predator and prey populations cycle through time, as predators decrease the numbers of prey. Lack of food resources in turn decrease predator abundance, and the lack of predation pressure allow prey populations to rebound.

References
·         Teaching And Learning With Simulation. Retrieved November 23, 2012, from http://www.ioe.ac.uk/study/MMACLD_02.html
·         Predation. Retrieved November 23, 2012, from http://www.globalchange.umich.edu/globalchange1/current/lectures/predation/predation.html

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