The applet requires Java 1.5 or higher. It will not run on Windows 95 or Mac OS 8 or 9. Mac users must have OS X 10.2.6 or higher and use a browser that supports Java 1.4. (Safari works, IE does not. Mac OS X comes with Safari. Open Safari and set it as your default web browser under Safari/Preferences/General.) On other operating systems, you may obtain the latest Java plugin from Sun's Java site.
created with NetLogo
view/download model file: workers_recipes.nlogo
The model describes with two different methods a close market.
The first method is an agent based model (ABM), also graphically reproduced. The firms are clearly represented by groups of coloured patches: in the firms appear recipes with a book shape that represent the working processes the product needs to be completed. At the same time workers are casually distributed on the field and walk casually looking for the production points. As they arrive, each worker is able to manipulate all the products he finds within a variable range (work_range). Then, he receives a salary and leaves the firm.
Only after their first job experience the workers begin to walk following the visibility of the firms symbolized by the diffusion of the colour around them but, because of their satisfaction for the earned salary, they will walk slower.
This event will reduce the affluence of workers in the firms and will be the cause of the following increase of recipes waiting to be produced. After a certain period, new workers will substitute the old workers, the production will rise and the process will start again.
The second method consists in a System Dynamic model of the same reality. In the diagram of the SD Modeler are reproduced the main quantities, the relations between them and the relative values. The results are showed in the plot at the right side of the screen.
The main procedure consists in the manufacture of the product. Each recipe represents the working processes needed by a product: it is defined by a list of numbers one and zero. Also the skill of the worker is constituted by the number one or zero.
In this way, the worker acts in the firm only subtracting the last item of the lists of the recipe that he finds within a range of few space units. When the product's list is empty the working process is considered completed and the recipe disappears.
The model is very easy to use. It is enough to setup and let it run along the time.
Moreover, it is possible to settle the initial number of elements of the model, the number of firms and the range of work of each worker.
The development of these values trough the time is represented on the plot below.
At first, notice that the colour of workers and products changes according to their condition in the production process. The workers are red when unemployed and blue as they enter in the firm. At the opposite side products are initially green, but become grey as they are worked.
Furthermore, the satisfied workers are yellow and it is evident their slowing down velocity of their moving. Each one of them will disappear after a certain number of circles.
Some changes would be appreciated. It would be interesting to work on the interaction of workers and products within the firm. The visibility should become a variable, depending on the production level. Also the generation of new elements should be related to other features and not already defined in frequency and quantity.
It is really interesting to examine closely the possibilities dues to the use of the lists and the operations on them.
Merlone U., Terna P., Population Symbiotic Evolution in a Model of Industrial Districts.