Operational Research - Herrera Cáceres

Scope and definition of network models: Many operations research situations can be modelled and solved as networks. Examples: Design of a network of pipelines for natural gas at a certain distance from the coast to connect the heads of the wells at a production point to a coastal distribution point with the objective of minimizing the cost of construction of the pipelines. Determination of the shortest route between two cities in an existing road network. Determination of the maximum capacity (in tons per year) of a pipeline network for coal sludge that connects coal mines in Wyoming with power plants in Houston (sludge pipelines transport coal by pumping water through specially designed pipes). Determination of the schedule (start and end dates) for the activities of a construction project. Determination of the minimum cost flow itinerary from oil fields to refineries through a network of oil pipelines. See the full lecture.

The Transhipment Problems : A transportation model allows only shipments that go directly from a supply point to a demand point. In many situations, shipments are allowed between supply points or between demand points. Sometimes there may also be points (called transhipment points) through which goods can be transhipped on their journey from a supply point to a demand point. Shipping problems with any or all of these characteristics are transhipment problems. Fortunately, the optimal solution to a transhipment problem can be found by solving a transportation problem. The Transhipment Problems Solution using LINGO functions

Assignment problem : The Assignment problem is a special type of linear programming problem in which those assigned are resources that are used to perform tasks. For example: - Employees assigned to jobs. - Machines, vehicles, or even periods to which tasks are assigned. - Plants to which products that must be manufactured are assigned. Assignment Problem       

Two particularly important types of linear programming problems : Transportation problem: It receives this name because many of its applications involve how to determine the optimal way to transport goods. However, some of its important applications -such as production scheduling- actually have nothing to do with transportation. Assignment problem: Includes applications such as assigning people to tasks. Although its applications appear to be quite different from those for the transportation problem, the issues of assignment can be considered a special case of the transportation problem. See the full lecture

Interpreting the LINGO output: Given the following LPM and its respective output in Lingo, it is required to build the respective associated optimal table. See the full lecture

LINGO Tutorials: Depending on the LINGO release, on the Internet you can get several tutorials to learn about how to use this important program. Below, some links of interest to get a tutorial or manual. In any case, you can extend the search and obtain a tutorial or manual according to the release installed on your computer. LINGO 15 Online Users Manual LINGO - The Modeling Language and Optimizer LINGO 8.0 Tutorial It is recommended to review and expand this information which has ben used in class and could be used to solve the model of the homework (Case Study - The company Dentsupplier).