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optimizaton « Systems Engineering Modelling and Simulation

Posts Tagged optimizaton

Reducing Cost of Road Maintenance for the Resources Industry

production-1891426_640Haul road in open mine has short durability. It is because haul road is constructed without asphalt/concrete pavement and passed by big vehicle with heavy load. There is some kind of decreasing quality of haul road such as improper cross section, inadequate roadside drainage, corrugations, potholes, ruts, and loose aggregate. Poor haul road quality will impact on increasing production costs and decreasing mine productivity. Usually open mine use motor grader to maintain the quality of haul road. Way of working of motor grader is to scrap the inadequate haul road surface.

There are some differences among the haul road segments such as characteristic, traffic density, kind of decreasing quality, durability, etc. Therefore, systematically grader route and schedule is needed to minimize the delay of haul road maintenance. Usually grader route and schedule just based on grader’s operator experience. There is no specific approach that can be used in grader route and schedule.

This research focused on grader route and schedule optimization in coal haul road maintenance. Optimization model in this research is designed using Bandit Algorithm. The objective of the optimization model is to minimize the maximum penalty. In this case, penalty is used to describe amount of loss that is caused by maintenance delay on each haul road segment. Grader start from the initial point to a road segment and moves over and over to the other road segment until working hour is over. Determination of he next road segment is based on weight of maintenance delay on each road segment. Greater the weight of the maintenance delay of a road segment, greater the probability of that road segment to be addressed by grader. Grader scraps if the road segment is late maintained and just passes if otherwise. When the working hour is over, grader stops moving and optimization model calculates the objective and records the route as a new solution. The steps are done again as many as have been determined (iteration). Solution with the best objective is chosen as the final solution.

With the probability, grader is not directly addressed to the road segment with the greatest maintenance delay weight to allow for the other road segments to be the next grader destination. This is because short term solutions have effect on long-term solution (whole solution); maybe the best short-term solution is not the best long-term solution. An example in a simpler problem is: we must determine route from city A to city D with 2 possible route that are A-B-D and A-C-D. With the distance between A-B < A-C, A-B is the best first movement. But for the overall movement, maybe A-B-D is not the closest route. Although the distance between A-B < A-C, distance of A-C and C-D can be closer than A-B and B-D.

Optimization model showed a significant cost savings for the mining operations by creating a more effective roads maintenance with reduce cost. With the pressure of low prices in the resources industry, a simple but yet complex optimization can help them stay more competitive.

This research is conducted by Denni and Dr. Komarudin.

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This is What You Should Do When You Have No Doraemon’s Magical-Anywhere-Door

There are times when we wish Doraemon’s magical-anywhere-door really does exist. If so, we can reach our destination without having to travel miles in a long time. But, since Doraemon does not exist, fortunately there is something we can do to at least save the mileage and time we sacrificed to travel from one to another places. Especially in case of post men or delivery couriers who have to visit a lot of destinations in such limited amount of time and capability.

Recently, a research assistant from Systems Engineering, Modeling, and Simulation Laboratory from Industrial Engineering major, Universitas Indonesia is conducting a research about Vehicle Routing Problem with Time Windows to optimize distribution route and schedule. It was first inspired by Indonesia’s current logistic condition which is still not optimal. It is proven by the decreasing index of Indonesia’s logistic performance during the past five years. One of the reason is the high Indonesia’s logistic cost which can be considered as the highest logistic cost in the world. And the one that contributes almost half of the logistic cost is transportation cost.

On the other side, customer needs are rising annually. Moreover, the growing online shopping market create an increasing demand of same-day delivery service. Based on McKinsey survey, online retailers as the main originator of B2C shipments, have a large interest to reduce delivery time in order to foster the products sale. Therefore, we need a better planning of distribution route and schedule, especially for delivery service providers and courier companies.

The purpose of research conducted at SEMS Laboratory about Vehicle Routing Problem with Time Windows (VRPTW) is to find the most optimum distribution route with lowest total distance yet still manage to fulfill all demand and considering the constraints of vehicle capacity and customers’ time windows.

Since VRPTW belongs to NP-hard optimization problems, our researcher used heuristic method which is translated to Netbeans 8.1 software in C++ programming language. They also use local search to perform simple iterations to produce fairly accurate solutions. Local search methods which are used in this study are exchange, two-opt, and insert. They can be applied to customers in the same route (intra-route) and customers in different routes (inter-route). Basically, these methods perform some iterations of moves that determine the most optimum combination and sequence of customers to visit. This will be finalized by using Lin Kernighan Helsgaun algorithm. The iteration will stop once it can not generate a better solution.

Fig 1. Illustration of 2-opt intra-route move

Fig 1. Illustration of 2-opt intra-route move

The resulting improvements will ultimately result in reduced transportation costs. Thus, vehicle routing problem with time windows can be a solution for urban logistic problems. So, when you do not have any Doraemon’s magical door, make yourself sure that at least you have a well-planned distribution route and schedule!

This Research is Conducted by Vincencia Sydneyta and Dr. Komarudin

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