# Posts Tagged Optimization

### How to optimize unequal area facility layout to maximize storage

Facility layout problem, especially with the unequal departmental area (UAFLP), is one of the problems studied in combinatorial optimization and has received the attention of many researchers in the past decade. The goal of UAFLP is to allocate departments into a facility to obtain the most efficient arrangement. The UAFLP study has a final objective to minimize the total cost of material handling between departments.

Competition in today’s business world is inevitable. Increasing the quality of productivity becomes one of the keys to success in facing competition with business management effectively and efficiently. This can happen by maximizing existing resources ie employees, machines, and other facilities. Therefore, the industry needs to be able to optimize production capability and effectiveness to face competitors. The production process becomes the key that needs to be managed effectively to minimize production costs with higher effectiveness.

Facility layout design has a close reinforcement to the size of the physical arrangement of elements in a manufacturing and service system, such as department, machinery, operational tools, and so on. The purpose of the facility layout design is the design with the minimum material handling cost. With proper facility layout, material handling costs can be reduced. In general, material handling contributes about 20-50 percent of the total. Reduction in the company’s operational costs, along with the increased efficiency of the production system becomes a necessity that every industry needs to do.

The problem of facilities layout that is often the researcher’s attention is Unequal Area Facility Layout Problem (UAFLP). Initially, UA-FLP was developed by Armor and Buffa (1963). They explain that there is a rectangular facility with a fixed Width and Height and several (n) departments that need to be allocated to the facility. There are some problems that have not found the optimal solution and require a long computation time. The goal is to reduce non-feasible solutions to reduce the complexity of possible solutions.

This research will develop a mathematical model using Mixed Integer Programming method based on Flexible Bay Structure. Some additional constraint functions will be attempted to be added to the model. Testing is done by comparing the effect of each additional constraint function that has different approaches in cutting the complexity of possible solutions. The comparison result of the combination of the constraint function used indicates which constraint function has a major influence in reducing the computation time of the model.

This research concludes that all simulated problem sets using additional constraints in the model can provide better computation time than before. The effect that occurs can be the value of the solution becomes not optimum or remain optimum. All computational time gives significant improvement.

This research is conducted by Randa Adi Saputra and Komaruddin

### Cracking The Truck Dispatch Problem in Open-Pit Mining to Enhance Competitiveness for the Coal Market

Indonesia is a country which has high diversity in energy and mineral resources. As an archipelago with an area of 1,910,931 km2, Indonesia has some of the pre-eminent resources such as petroleum, natural gas, nickel, coal and others. In coal, Indonesia is listed as one of the largest coal producer in the world in 2014. As one of the highest coal producing countries, Indonesia has a reliance on the use of coal for generating electricity or power plant. This is in line with the Indonesian government program in the long-term energy mix of coal has increased the portion of the year 2013 by 24% to 2025 by 33%. But in fact it actually happened inversely where increased production of domestic coal is not followed by a competitive price.

The existence of weakening coal prices, which decreased from year to year, causing the mining sector, especially companies engaged in coal experienced significant negative impacts. One of the most essential where companies are not experiencing growth on corporate profits, but declined.

Based on these phenomena is the only way for the company to continue running the business activities through efficiency measures on many things to be able to cover operational costs. One of the efficiencies that can be done such efficiency on the operational side.  As mentioned by Alarie & Gamache (2002) and Ercelebi & Bascetin (2009) the material transportation represents 50 per cent of the operating costs for an open pit mine. Therefore, one of the efficiencies that can be done and has a substantial impact through efficient on truck dispatching problem in the mine area

SEMS was proposing to overcome this problem using simulation and optimization approach to analyze the complexity of truck dispatch problem in open pit mining. This approach uses the look-ahead algorithm and  multi-stage algorithm. Solving the issue focuses on the development of look-ahead methods that will be applied to the truck dispatch problem. Simulation and optimization approach on this issue is run simultaneously with the help of software ProModel as the media to solve the problem. Look-ahead algorithm is an approach to solve the problems of the assignment of the fleet to look ahead what will happen near future with based on previous information system gathered as a reference to decide the scheduling for entities that exist in back of the queue. This research basically to answer the question about where this truck should go now and when it leave this place in order to maximaze amount of coal production. The output of the research is to obtain the best assignment rules for truck dispatch problem with four indicators are, amount of coal production, productivity of loader, productivity truck with block and without block.

Using the model, a significant improvement on amount of production has been achieved to enhance competitiveness coal market.

This research is conducted by Achmad Yusaq Faiz Fadin, Komarudin, and Armand Omar Moeis.

### SEMS at ICMS 2011 – Thailand

Two of our researchers, Armand Omar and Aziiz Sutrisno, was presenting at th 4th International Conference on Modelling and Simulation, Phuket, Thailand on April 25-26, 2011. Both of their papers were among 179 paper selected from 512 paper submissions, representing 35% acceptance rate.

Pak Armand presented his research with Pak Komarudin on “Combination of Dummy Department and Wheel Structure Representation for Facility Layout Problems with Empty Space”.

Pak Aziis presented his research with Pak Akhmad on “Systems Dynamics Model for Understanding Contributions of Biodiesel Industry in Indonesia”

### Optimization Workshop 2011

In order to prepare final year students on using optimization software for their final project, SEMS lab is conducting an introductory workshop on optimization, led by Mr. Komarudin. The workshop is held for 3 days.