Rajat Bhagwat

An application of the integrated AHP-PGP model for performance measurement of supply chain management

The performance measurement problem has gained great attention in business and operations management literature. The first objective of this study is to determine the required performance measures and to develop a model for performance evaluation, based on these selected measures using analytical hierarchy process (AHP) methodology. The second objective is to explain how an integrated AHP-PGP (pre-emptive goal programming) model can be used in performance measurement while optimising the overall performance. An integration of AHP and multi-objective PGP is used to consider both quantitative and qualitative performance measures in optimising the overall performance of the system. The integrated model is presented with a real-world application using source data provided by a survey conducted in India. Findings demonstrate that the integrated AHP-PGP model can be useful to all supply chain industries in their day-to-day performance measurement decisions.

Comparative performance analysis of a flexible manufacturing system (FMS): a review-period-based control

The flexibility of a flexible manufacturing system (FMS) has provided it with the capability to become one of the most suitable manufacturing systems in the present manufacturing environment of customized and an increasing variety of products with shorter life cycles. Significant research has been made on flexibility from different points of views. The paper focuses on the study of flexibility in FMS from the view of a decision-and-information system. In modelling flexibility and other physical and operational parameters of an FMS, researchers have mostly assumed a decision-and-information system has the capability of real-time control. The literature reports qualitatively that real-time control may be difficult to achieve and justify economically. The paper presents a comparative study of an FMS operating under real-time control, review-period-based control and reactive control. It also focuses on the comparative performances of the key parameters such as routing flexibility and control strategies of an FMS operating under these different modes of a decision-and-information system. It contributes an approach using simulation under Taguchis method to study the various factors contributing to FMS performance and identifies the critical parameters for improving performance. The result shows that review-period-based control can be effectively implemented in an FMS with a lower flexibility level. Smaller review-period size can perform comparable with real-time control. The decision-maker must ensure the FMSs capability of having real-time control, otherwise it may result in a reactive control that may considerably deteriorate the performance. The results under Taguchis method indicate that the routing flexibility and control strategy should have maximum relative percentage contributions in the performance of an FMS, while the decision-and-information system should have the minimum. Increasing the relative percentage contribution of a decision-and-information system may deteriorate the performance of a given FMS.

Increase in flexibility: productive or counterproductive? A study on the physical and operating characteristics of a flexible manufacturing system

In time-based performances of a manufacturing system, flexibility has played a pivotal role. Significant research efforts have been made from defining the various types of flexibility in flexible manufacturing systems (FMS) to the performance measurement index of flexibility levels. This paper focuses on the physical and operating characteristics of alternative machines (available by the virtue of flexibility), which may not have been explicitly modelled with flexibility. The decision-maker needs to know how physical and operating characteristics such as processing time, machine setting time, tool changing time, transportation time, control strategies enforced, etc. may influence the changed level of flexibility in an FMS. Does an increase in flexibility have the expected benefits or not? If benefits are present, then up to what level of flexibility? Answers to these questions will provide an insight to the decision-maker to decide a gainful level of flexibility for a given physical and operating characteristics of an FMS. This paper contributes an approach to identify productive and counterproductive performance zones of an FMS at different flexibility levels while considering physical and operating characteristics. It also demonstrates the need of modelling explicitly the physical and operating characteristics of a system with flexibility, and it presents a simulation study of these parameters for a given FMS. The results show that expected gains from an increasing level of flexibility may not be present while considering physical and operating characteristics. Flexibility can be increased strategically up to a certain level with benefits when considering the physical and operating characteristic of the system. A further increase in flexibility level may be counterproductive.

Development of a decision support system for air-cargo pallets loading problem: A case study

Abstract This paper presents a two-phase intelligent Decision Support System (DSS) for Air-Cargo Loading Problem (ACLP). This problem can also be viewed as three dimensional, non-identical, multiple bin-packing problem because of the different shapes and specification for the air cargo pallets. Phase-I of the proposed decision support system discusses the Linear Programming (LP) model to decide the lower bound for global minimum cost of pallets to load the available cargo based on its weight and volume. Phase-II heuristic of the proposed system efficiently loads the cargo-boxes and generates the loading plan of each pallets with minimum deviation from the lower bound, decided in earlier phase-I, would be the most suited one. The contribution of this paper lies in developing a new approach for the three-dimensional loading plan of the air cargoes on the different shaped and sized pallets. The constraints related to the shape and size of the pallets, related to the airlines and the shipping destination are also taken in account in the proposed system, which are not adequately discussed in the previous literatures. For ranking of cargo-boxes, a method of rank revision based on left empty-space has been suggested. The proposed DSS has been implemented on the real time data sets taken from freight forwarding company. The data sets contain the information about the 54 different classes of the total 671 cargo-boxes. The problem considered in this paper is more complex than the some discussed in the literatures. At number of instances, the developed system has successfully loaded the pallets up to the 90% and above by volume.

Study on suppliers’ flexibility in supply chains: is real-time control necessary?

In a supply chain, the suppliers’ flexibility is considered as a tool to cope with the environmental uncertainties. Flexible suppliers are capable of supplying/processing other jobs in addition to the one for which they are the original supplier. In a cluster of flexible suppliers, it is expected that flexibility of suppliers be utilized more expressively through better control of the supply chain. The online real-time information system is considered as one of the tools for effective control of the supply chain. However, in a cluster of flexible suppliers, the physical and operating characteristics of alternative suppliers (available by virtue of suppliers’ flexibility) may vary from each other for doing the same operation, which may result in a different lead-time to process the same job. This paper presents a simulation study on suppliers’ flexibility level (SFL) in relation to information system automation level of the supply chain and physical characteristics of the flexible suppliers. This paper con...

Performance measurement model for supply chain management in SMEs

In Supply Chain Management (SCM), performance measurement can facilitate understanding and integration among the supply chain partners. The purpose of this paper is twofold: first, to review the existing SCM performance measurement framework based on the Analytical Hierarchy Process (AHP) and Balanced Scorecard (BSC) models reported in the literature. Second, based on the prioritisation of the suggested performance measures/metrics and performance at different decision levels, a mathematical model is developed to optimise the overall performance measurement of SCM for Small- and Medium-sized Enterprises (SMEs).

Taguchi's Method Analysis of an FMS Under Review-Period-Based Operational Controls: Identification of Control Periodicity

Flexibility of flexible manufacturing systems (FMSs) has been considered as an effective tool to compete in the present manufacturing environment. Enormous research efforts have been made to harness the benefits of flexibility through superior control strategies. While modeling flexibility and control strategies, researchers have mostly assumed an information system that can provide real-time control. Literature qualitatively reports that the real-time control can be highly capital intensive and difficult to achieve. This paper focuses on FMS operating under review-period (RP)-based control and presents a combined study of routing flexibility (RF), control strategies, and information system under Taguchis method using simulation. RP-based control for FMS has been compared with real-time control. This paper contributes an approach for the decision maker to study the performance of an FMS operating under RP control and to identify the periodicity (time interval) of RP that will not deteriorate its performance in comparison to real-time control. It also helps the decision maker to reach a tradeoff between RP-based control and real-time control. The results show that RP-based control can be effectively implemented on an FMS having lower RF level. RP-based control can outperform real-time control with a superior control strategy and smaller RP size. The results under Taguchis method suggest that the RF and control strategy should have maximum relative percentage contributions in FMS performance, whereas contribution of the RP (information system) should be minimum. Increasing the relative percentage contribution of the information system may deteriorate the performance of FMS. The information system is needed as a catalyst to facilitate the contributions of other factors in improving the FMS performance and not its own contribution

The effect of responsiveness of the control-decision system to the performance of FMS

Abstract In Flexible Manufacturing System (FMS), decision-making process is one of the key aspects for its performance enhancement, particularly for shop-floor control, where operation managers need to make a large number of control decisions. A term called ‘response-time’ in decision-making process has been defined in this study, which refers to a lead time in decision-making and its implementation. This paper contributes a methodology for decision-maker to study the decision-making process and identify a suitable decision-making approach, while considering critical factors such as decision automation levels, routing flexibility levels, and control strategies. Considering the complexity in modelling an FMS with routing flexibility levels, control strategies (sequencing and dispatching rules), and decision-making process with information system, computer simulation modelling has been employed to study the makespan performance. The results show that decision-making process with response-time for FMS control performs as good as with the real-time control when routing flexibility level is low. Furthermore, under some specific situations, it even outperforms the real-time control. This research gives insight to decision-maker to identify whether a decision system with response-time will be more suitable and economically justified, or real-time decision-making system is more appropriate.

A Decision-Information-Synchronisation perspective on the performance of FMS

The performance of a Flexible Manufacturing System (FMS) largely depends on how the control system can control the flow of entities in the system. The control system takes control decisions based on the information provided as an input to the decision-making process. Therefore, it is important that the decision-making process and information systems operate in a synchronised manner with respect to the FMS characteristics. This can also be referred to as a Decision-Information-Synchronisation (DIS) operating zone implemented in the control system. To study the DIS in the present research, three types of visibility for decision-makers in FMS shop-floor control have been identified: (1) no local visibility, (2) physical local visibility and (3) physical and information local visibility of decision-maker/operator. These alternative visibilities and automation levels of decision and information system provide the hybrid environments of FMSs control. The current paper presents an approach to identify the DIS operating zone of FMS with suitable visibility of decision-maker and automation level. Simulation results show that under non-real-time control (low automation level in decision and information system) with physical local visibility, the FMS system performs comparable with the real-time control (high automation level in decision and information system) when routing flexibility levels are presented. Under the current global competitive environment, this study helps industrial managers determine a suitable level of visibility and automation in planning an FMS control system in order to obtain the desired performance at the lower cost.

Simulation study of decision delays in manufacturing systems using Taguchi methods

Online control strategies employed in the manufacturing systems involve decisions that may entail significant time delays depending on the level of computerization in the shop floor. We refer to these delays as decision delays when they cause delays in decision processing and implementation. In the domain of discrete part manufacturing systems with defined levels of flexibility, it is essential to explicitly model and analyze the effect that decision delays have on the performance of a given online control strategy. In this paper we present a simulation study of a manufacturing system and a study performed under the Taguchi methods. The aim was to identify the contribution of various factors, including the decision delays, in a manufacturing system. The results indicate that the relative contribution of decision delay on makespan performance is maximum. Further the relative contribution of other factors such as routing flexibility and control strategy decreases as the delays increase. Thus to avail the benefit of increased routing flexibility it is useful to contain the delays.