Project Title

The Bit Torrent Network

Authors

Kashi Trathen and Rob Ball

About

This model simulates the dynamics of a peer-to-peer bit torrent network. Bit Torrent is a popular protocol for distributing large files amongst multiple users over the internet, and studies have shown it to account for approximately 70 percent of total IP traffic (Yinka, 2005). It works by breaking a file into many segments (usually 100 or more depending on the size of the file) and allows individual users who are downloading the file to simultaneously upload completed segments to other users. This means that users are downloading from each other as well as from the server or the initial distributors (Cohen, 2008). Compared to traditional web hosting where everyone downloads directly from the server, Bit Torrent significantly reduces bandwidth usage and hardware requirements for the initial distributor, thereby resulting in substantial cost savings. In some cases (as this model will demonstrate) it is possible for the initial distributors (seeds) to drop out completely without undermining the network, provided enough file segments are in distribution.

ImageLink(Ball-Trathen-screen.png,width=300px)

Code

attachment:BallTrathen-BitTorrent.nlogo

Project Title

Highway Traffic Incident Reduction

Authors

Jacqui Zucco and Ravi Dutta

About

A primary consideration for the road traffic authorities when setting speed limits on roads is to reduce the likelihood of accidents occuring. Speed impacts on the likelihood of crashes being a constributing factor in one out of five accidents. Research suggests that the risk of involvement in a road traffic accident doubles with every 5km/h increase in speed over 60km/h. Whilst safety on roads is an important concern to the traffic authorities they must weigh this against the need for efficient movement along the roads. They balance these issues by attempting to maximising throuhput on the roads whilst minimising the likelihood of accidents. The road traffic authorities have even more recently been biased towards safety by setting lower speed limits in many areas. Is this approach justified? Many drivers on the other hand believe that driving at higher speeds will allow them to reach their destination faster. Is this an accurate belief?

ImageLink(Zucco-Dutta-screen.png,width=300px)

Code

attachment:ZuccoDutta-HighwayIncidents.nlogo

Project Title

Do Differential Speed-limits Lead to Crash Reduction?

Authors

Dinendra Chandrasinghe and Yunhee Park

About

This project models the movement of cars, p-platers and trucks on a one way highway with two lanes. The underlying research question of the model is to find out the best policy that could be implemented on the speed limits of vehicles so that it leads to the least number of accidents on the highway. In order to investigate this policy, we carry out the following actions: 1. Placing the same speed limit on all three types of vehicles (base case scenario) 2. Placing differential speed limits on all three types of vehicles 3. Placing the same speed limit between 2 types of vehicles and a differential speed limit on the third type.

ImageLink(Chandrasinghe-Park-screen.png,width=300px)

Code

attachment:Chandrasinghe-Park-TrucksOnHighways.nlogo

Project Title

Overfishing

Authors

Andrew Johnson and Savannah Seixas

About

The NetLogo Overfishing model explores the real-life crisis of overfishing facing the world's fisheries industry and its effect on the ecosystem. Fishing is considered to be unsustainable if it tends to result in extinction of the fish population. Conversely, fishing is considered sustainable if it maintains the ecosystem over time, despite fluctuations in population sizes. To begin addressing this issue, users of the model are invited to consider a very simple ocean ecosystem containing only plankton (producer) and fish (consumer). Users are able to explore the effects on the population of each species by adjusting the available level of sunlight, initial populations, their reproduction rates and energy. The effects of predation are further extended by introducing predators (a consumer of fish) into the ecosystem. Finally, users can explore the effects of fishing through the introduction of fishing trawlers. Users are challenged to find a sustainable level of fishing by adjusting the initial number of trawlers in the ocean, changing the maximum legal catch of fish and varying the annual global change in demand for fish.

ImageLink(Johnson-Seixas-screen.png,width=300px)

Code

attachment:JohnsonSeixas-Overfishing.nlogo