Nasr Al-Hinai

Optimisation techniques for planning the petrol replenishment to retail stations over a multi-period horizon

The problem of planning the petrol station replenishment problem (PSRP) consists in making simultaneously several decisions, such as determining the minimum number of trucks required, assigning the stations to the available trucks, defining a feasible route for each tank-truck, etc. The objective to be achieved is usually defined as the minimisation of the travelled distance by the tank-trucks to serve all of the distribution stations. Traditional studies in the literature model and solve this problem over a time period of one single day. Only few works have recognised the fact that extending the time horizon to several days may yield important savings for the delivering company. The goal of this paper is to survey the optimisation techniques that support the petrol companies in improving their delivery performance over a multi-period planning horizon. We present the mathematical optimisation models that have been developed for both the t-day and periodic variants of the problem and discuss the heuristic methods so far developed for their solution.

The Periodic Petrol Station Replenishment Problem: An Overview

This paper focuses on the periodic aspects within the Petrol Station Replenishment Problem when defined on an extended planning horizon of t working days. It has the aim of surveying the scientific literature on this topic and giving an overview of the modeling issues, mathematical formulations, and solution approaches related to the Periodic Petrol Station Replenishment Problem (PPSRP).

Metrics of product modularity: lessons learned from case companies

Purpose Modular product development is a turning table concept in terms of benefits and impact in manufacturing companies. It offers added benefits to the companies with respect to reduce lead-time, improve assemble ability, agility in supply chain management, promote product family and enhances customers’ satisfactions. This research is conducted to identify the patterns of modular product development strategy with measurement techniques. Design/methodology/approach Both quantitative and qualitative approaches are taken to conduct this research. In the qualitative section, relevant data on product design is collected from six case companies. On the other hand, in the quantitative section, collected data is analyzed to measure the product modularity level with the case companies. Findings This research identifies potential metrics, which can be used successfully to measure product modularity level or index in manufacturing industries. Selection of such metrics also depends on individual company’s objectiv...

Jobshop scheduling for skill-dependent Make-to-order system

In todays competitive environment many companies are shifting their production strategy from Make-to-Stock to Make-to-order (MTO) system. The reasons are to cater product as per the need of customer and to reduce inventory holding cost. In MTO system, production starts only when order arrives to the shop floor and gets confirmed. Production planning of such system includes scheduling of orders to the production periods and allocation of workers at different work centers. Complexity in such environment arises when the time to produce products is skilled dependent and from the shop floor condition. Under such situation, efficient scheduling of orders and allocation of workers at different work center play a major role to improve system performance. This research developed a mathematical model for workers allocation problem in a job shop production environment with an objective of minimizing makespan.

Production Planning for Make-to-Order Flow Shop System Under Hierarchical Workforce Environment

In make-to-order system orders are scheduled for production based on the due date agreed with customer and the strategy of company. Production planning of such system includes scheduling of orders to the production periods and allocation of workers at different work centers. Complexity in the system arises when the operation to perform next and its processing time is skilled dependent where a higher qualified worker type can substitute a lower qualified one, but not vice-versa. Under such working environment, efficient scheduling of orders and allocation of workers at different work center play major role to improve system performance. This paper develops a mathematical model for make-to-order flow shop system under hierarchical workforce environment. The model helps identify optimum schedule of orders and allocation of workers with an objective of minimizing the weighted average earliness and tardiness. A heuristic method is also proposed to overcome the complexity of mathematical model and solve the problem efficiently. Numerical analysis indicates that proposed heuristic is capable of finding optimal or near optimal solution in a considerably reduced amount of computational timing.