Satyaveer Singh Chauhan

The concave cost supply problem

Abstract This paper is divided in two parts. In the first part, we consider the case where several providers feed a single manufacturing unit periodically in order to satisfy a given demand. The cost incurred when a provider feeds the manufacturing unit is a concave function of the quantity delivered. Furthermore, each provider either delivers a quantity that lies between a minimum and maximum value or do not deliver anything. We are introducing some properties of an optimal solution and derive a heuristic algorithm from these properties. A numerical example illustrates this approach. In the second part of the paper, we consider the case where several providers feed periodically several manufacturing units in order to satisfy given demands. A heuristic algorithm is proposed. The results provided by this algorithm are compared with the optimal solution in the case when the costs are linear for a strictly positive quantity and equal to zero otherwise.

Strategic capacity planning in supply chain design for a new market opportunity

This paper addresses the problem of supply chain design at the strategic level when production/distribution of a new market opportunity has to be launched in an existing supply chain. The new market opportunity is characterized by a deterministic forecast expected to occur per period. The product (or service) is assumed to be produced (or provided) in a three-stage capacitated supply chain where the first stage concerns suppliers, the second stage producers and the final stage customers. There could be multiple alternatives at each stage which are defined as nodes. Nodes in each stage are connected to the next stage through capacitated transportation systems. Production capacity at the second stage (i.e. producers) are also limited since they may already be involved in other existing activities. The objective is to perform strategic capacity planning in the supply chain in order to meet the demand of the new opportunity at minimal cost. A linear running cost is associated with each node. If the decision is to increase the capacity of a node, then a fixed cost applies, followed by a cost that is proportional to the additional capacity. The overall problem can be modelled as a large-scale mixed integer linear programming problem. A solution algorithm is developed to overcome difficulties associated with the size of the problem and is tested on empirical data sets. The overall contribution is an analytical tool that can be employed by managers responding to the new market opportunity at the strategic level for supply chain design.

Approximation of the supply scheduling problem

The supply scheduling problem consists in finding a minimum cost delivery plan from a set of providers to a manufacturing unit, subject to given bounds on the shipment sizes and subject to the demand at the manufacturing unit. We provide a fully polynomial time approximation scheme for this problem.

Opportunistic supply chain formation from qualified partners for a new market demand

This paper addresses the problem of short-term supply chain design using the idle capacities of qualified partners in order to seize a new market opportunity. The new market opportunity is characterized by a deterministic forecast over a planning horizon. The production–distribution process is assumed to be organized in stages or echelons, and each echelon may have several qualified partners willing to participate. Partners within the echelon may differ in idle production capacity, operational cost, storage cost, etc, and we assume that idle capacity may be different from one period to another period. The objective is to design a supply chain by selecting one partner from each echelon to meet the forecasted demand without backlog and best possible production and logistics costs over the given planning horizon. The overall problem is formulated as a large mixed integer linear programming problem. We develop a decomposition-based solution approach that is capable of overcoming the complexity and dimensionality associated with the problem. Numerical results are presented to support the effectiveness of this approach.

Concave Cost Supply Management for Single Manufacturing Unit

The considered problem consists of product delivery from a set of providers to the manufacturing units (single unit and single planning period in our case). The cost function is concave. Given the lower and upper bounds on the shipment size for each provider, the demand of the manufacturing unit has to be satisfied. In this chapter it is shown that this optimisation problem is NP-hard even to find a feasible solution to this problem. Considering the problem in integer programming formulation we propose a pseudo-polynomial algorithm, using the dynamic programming technique. Some possible approaches to solving the problem with multiple manufacturing units are discussed.

Sustainable mobility solutions: a pre-implementation questionnaire study for carsharing

This article presents a pre-implementation questionnaire study for a new carsharing system in La Rochelle, France. The questionnaire seeks responses on four main factors: profile of the users, transportation behaviour of users, willingness to use carsharing and preferences for new carsharing stations in La Rochelle. The target groups surveyed were city residents, tourists, businessmen, students and city transport organisations namely city of La Rochelle, CdA La Rochelle and Conseil Generale du Charente Maritime. A total of 500 questionnaires were distributed in-person and a response rate of 81.4% was received. The findings of this study reveal useful information on the feasibility of the offer, user motivations and service design aspects for the new carsharing system. It was found during the study that appropriate marketing strategies and awareness campaigns are required to inform people about carsharing. Other areas of improvement are ensuring availability of vehicles at times, easy access to carsharing stations, easy return procedure for vehicles after use, low trip costs and providing vehicles suited to user needs. These findings have strengthened the need for a new carsharing system in the city and have identified appropriate operational factors for its implementation.

Approximation solution of the supply management problem

The problem is considered of optimizing the product delivery from suppliers to consumers. The size of each open supply is bounded both below and above, the size of consumption for each consumer is bounded below, the supply cost functions are linear for nonzero volumes of supply. A fully polynomial time approximation scheme is proposed for this problem in the case of one consumer, and the complexity of the problem is studied in the general case.