Team Three: The Concept Study

Real Life Problem

There is a freshwater spring 5 inches below ground level. It is the water source for a town (in which the people are 1/2" tall) which is 15 inches away. The problem is that there is a 10 inch wide gorge (huge for such little people) between the two sources, and it is rumored that there is contaminated water in the gorge. Now the town needs water to irrigate crops and to drink. The goal, then, is to get clean water to the town. As many or as few legos as desired may be used for the design. Note, however, that centennial wind storms in the gorge are known to gust to speeds capable of producing up to two pounds of force at the gorge's center. The building materials are expensive, as well, at $1/block unit. Three motors are available for use in the structure (they have been donated by a local company in the town). Any additional motors will cost extra, though.

You, as the head engineer of this project must find a way to clean the water (there is unknown sediment and possible acid rain contamination) and transport it to the town. Obviously, cost is a major consideration. If the project cannot be completed both on time and affordably, the town will be ruined and the people will be forced to move away!

Before you begin, please present a proposal to the town council. They would like cost estimates and detailed plans about how you and your project team are going to get clean water to them.

Engineering Concepts

This project will teach a number of fundamental engineering principles. The project encompasses many engineering disciplines such as civil engineering (the aqueduct), environmental engineering (decontaminating the water), chemical engineering (energy balances), mechanical engineering (pumps and motors), aerospace engineering (fluid flows), and computer science (the control software). Students will learn simple software engineering, basic chemistry (neutralizing an agent in the water), and applied physics (supporting weight on the aqueduct, if that is the design they choose). They will also learn to work as a team on a multidisciplinary engineering project. Concepts such as planning out the project ahead of time (the written proposal to the town council), meeting minimum design constraints, and working with a budget will be emphasized throughout the project.

Goals

The overall goal of the project is for students to get "clean" water to the town in the best way possible. The educational goals are fairly apparent and are detailed in the Engineering Concepts section. This project will provide for a fair amount of creativity but will still direct students towards the best design. The students will see the benefit of planning ahead, and, through friendly competition, will understand the advantage of minimizing the cost while maintaining end-user satisfaction.

Flexibility/Trade-Offs

There are a number of ways in which this project could be designed. Foremost among the variables to be optimized are the water contamination, the water pump acquisition, and the method for water transportation.

One option for the water contaminant could be the "given" fact that there are microorganisms that must be destroyed for the water to be drinkable. In this case a certain amount of hydrochloric acid (diluted) could be added. However, the amount of HCl added could not exceed a certain point or it would be harmful to the inhabitants. This level could be maintained by the pH meter. Another option to simulate water contaminantion could be the presence of acid or base in the water which would have to be counteracted. Finally, a sediment could be in the water which would have to be filtered out.

The pumping device could be bought pre-made and just installed. Another option could be to require the students to construct build own pumps, perhaps out of a motor and propellors or with gears. A pumping device may not even be required - the students may be able to move the water some other way.

Water transportation may be handled via aqueduct. This would simply consist of a pipe on a bridge or a pipe under a bridge. The water could even possibly be pumped through the Legos themselves, if there is no leakage!

Equipment

Since there is more than one way to solve this problem of transporting and clean ing the water, there is more than one possible set of equipment required. Some pieces will be essential regardless of the specific solution:

All the legos given in our kits.
At least 2 motors.
4 beakers or other comparable liquid receptacles.
Tubing - rubber - enough to span the distance of the bridge and then some extra.
5. A pH sensor.
The CHEMICALS - yet to be determined.

Depending on how each group solves this problem, other costly "necessities" may be:

Another pH sensor.
A stir rod and glue.
Elevated platforms (this could consist of a book - but it still counts).
More beakers.
Touch sensors.
Color sensors.
A pump.
More motors.
A Servo.
Food coloring.
Lego people to mill about the bridge (these cost extra, too).
Propellor(s).
Temperature sensors.
Graduated cylinders.

Everyone will receive the general equipment--but groups will have to pay extra for the other "necessities." A group may want to purchase the Lego Dacta Pneumatic Building Set, which consists of a hand pump, pheumatic switches, tubing, connectors, etc. and costs around 40 dollars.

Design Performance

Several considerations can be used to evaluate the performance of the students as they attempt to complete the project detailed above. The most readily available method of evaluation is the relative cost of building the structure. Given that the building material is a countable resource, a price per piece can be levied. The group presenting the most cost-effective project, while upholding the constraints of the design will be recognized as the best concept.

The various constraints which will be enforced in the design phase of the project will present alternative methods of judging the performance of the projects. For instance, sizing restrictions will prevent the design of a structure which does not fulfill the function of delivering water to its destination with efficiently as as possible.

Another possible constraint to levy on the design is the amount of water to be transported through the structure. Since the residents of the world model need a certain amount of water, the required quantity must be delivered in a timely fashion such that the supply does not diminish beyond a certain point. Flow regulation, then, is an important design consideration.

Since this project deals with the transport of a contaminable resource, the level of contamination must be kept to a minimum. Therefore, a pH level constraint can be imposed which, like the previous constraints, can be a guage of project performance. If pH is not mainatined within a certain range, then the project is not performing to specifications.

There are quite a few options regarding the evaluation of the overall project. As such, the project phase as a whole becomes a competition in which a high score is given, first and foremost, for a project which meets all of the design constraints, The score is then increased for any design which minimizes the required construction cost. In this way, a fair scale is created with which to measure the performance of all participating designs.