A note on ‘A two-level supply chain with consignment stock agreement and stock-dependent demand’

This note points out that the cost functions within Zanoni and Jaber [Zanoni, S. and M. Y. Jaber. 2015. “A Two-level Supply Chain with Consignment Stock Agreement and Stock-dependent Demand.” International Journal of Production Research 53: 3561–3572] might be incorrect due to misuse of demand representation. By incorporating Braglia and Zavanella’s consignment stock model and relaxing the zero-inventory reordering constraint, Zanoni and Jaber made extensions of the integrated vendor–buyer supply chain with stock-dependent demand in Sajadieh, Thorstenson, and Akbari Jokar’s proposed model. However, Sajadieh, Thorstenson, and Akbari Jokar’s model has different scenarios than Braglia and Zavanella’s model, and these inconsistencies cause false formulation in Zanoni and Jaber’s paper. In this note, we first formulate the justified cost functions and then present characteristics of the corrected model.     

A technical note on ‘Analysis of closed loop supply chain using genetic algorithm and particle swarm optimisation’

This study analyses the mixed-integer linear program (MILP) proposed by Kannan et al. [Kannan, G., Noorul Hag, A., and Devika, M., 2009. Analysis of closed loop supply chain using genetic algorithm and particle swarm optimization. International Journal of Production Research, 47 (5), 1175–1200] in their paper entitled ‘Analysis of closed loop supply chain using genetic algorithm and particle swarm optimisation’. Since we find inconsistencies in the model, we propose modifications to rectify the flaws. The revised model is presented and tested using a hypothetical problem.     

Optimal collection and remanufacturing decisions in reverse supply chains with collector’s imperfect sorting

We consider a reverse supply chain comprising two independent companies: the collector and the remanufacturer. The collector is responsible for sorting the collected used products and then transporting the ‘remanufacturable’ items to the remanufacturer. As sorting is not perfectly accurate, the misclassification errors affect the optimal decisions in the reverse supply chain. We focus on the optimal collection quantity for the collector and the optimal order quantity for the remanufacturer using game theory under both deterministic and uncertain demand. We characterise the optimal solution and show that under certain conditions, the remanufacturer should allow the collector to transport more ‘remanufacturables’ than the order quantity. We then examine the case where both the collector and the remanufacturer belong to a single company with centralised decision-making and compare the optimal collection quantities under both structures of the reverse supply chain.     

A note on ‘Economic manufacturing quantity in a just-in-time delivery system’

This comment is made on a paper by Golhar and Sarker who showed that it is economically advantageous for a supplier to participate in the just-in-time delivery system. Although the general conclusions are correct, one of the conditions under which the results are obtained is not necessary. Also, the optimal production quantity is not independent of delivery quantity though their interdependency is in a rather indirect manner.     

Sharing the ‘fame’ of ISO standard adoption: quality supply chain effects evidence

The objective of this paper is to provide an empirical evidence for whether the hierarchical position (determined by firm’s quality strength) of different types of quality supply chain categories implies the same hierarchy in terms of economic gains. Using data collected in France through a survey, we distinguish between four types of quality supply chain categories that help us to empirically construct a relationship between firms and their suppliers (quality certified/non-quality certified). Our findings, from a two-regime switching model, reveal that there is a positive correlation between the hierarchical positions of the quality supply chain categories and the impact on firm performance (measured by profit per employee).     

A note on ‘A bivariate optimal replacement policy for a repairable system’

An error appearing in equation (3) of Y.L. Zhang (J. Appl. Prob., 1994, 31, 1123–1127) has been pointed out by S.H. Sheu (Eur. J. Oper. Res., 1999, 112, 503–516) and the correct expressions (25)–(27) given accordingly on pp. 510–511. However, the derivation of the key expression (27), the long-run expected loss rate, was not presented. The purpose of this note is threefold. First, since a monotone process (e.g. an arithmetic, geometric, or arithmetic–geometric process) approach, as discussed by K.N.F. Leung (Eng. Optimiz., 2001, 33, 473–484), is considered to be relevant, realistic, and appropriate to the modelling of a deteriorating system maintenance problem, it is worth explicitly developing this expression, which is of benefit to the subsequent studies. Secondly, equation (3) in Zhang (1994) Zhang, Y. L. 1994. A bivariate optimal replacement policy for a repairable system. J. Appl. Prob., 31: 1123–1127. [Crossref], [Web of Science ®] , [Google Scholar] is shown to be fundamentally correct and so it can be viewed as an alternative method of formulating similar bivariate cases. Thirdly, although equations (4) and (5) in Zhang (1994) Zhang, Y. L. 1994. A bivariate optimal replacement policy for a repairable system. J. Appl. Prob., 31: 1123–1127. [Crossref], [Web of Science ®] , [Google Scholar] have been logically and correctly derived, both can be readily reduced to their simplest forms which are derived here.     

‘A blessing in disguise’ or ‘as if it wasn’t hard enough already’: reciprocal and aggravate vulnerabilities in the supply chain

We investigate the interrelations of structural and operational vulnerabilities in the supply chain (SC) using discrete-event simulation for a real life case study. We theorise a notion of SC overlays and explore conditions surrounding their appearance. Such overlays occur if the negative consequences of changes in a SC structure as a result of a disruption are either amplified or mitigated by changes in the operational environment. We hypothesise that these overlays can be both reciprocal (i.e. complementary or mitigating) and aggravate (i.e. concurrent or enhancing). Our approach can be used for an efficient management of SC resilience capabilities by varying their levels over time. We show different ripple and bullwhip effect profiles, which lead to either reciprocal or aggravate overlays, and then we develop recommendations on the overlay-driven dynamic variation of resilience capability levels in order to enhance both SC resilience and efficiency through dynamic redundancy allocation. The results can be of value in selecting and deploying operational policies at the right time and scale during and after the recovery periods. Restricting analysis to the disruption period only and ignoring operational dynamics after capacity recovery can result in misleading or inefficient SC resilience and recovery policies.     

Analysis of retailers’ coalition stability for supply chain based on LCS and stable set

To attain the general form of stable coalition structure, this paper addressed the problem of retailers’ coalition stability in a two-stage supply chain consisting of one supplier and multiple retailers. A profit gain function was established via introducing market gain coefficient and coalition cost coefficient for different coalition structures. Based on the function, the profit of each retailer in all kinds of coalition structures was analysed, and the general feature of a stable coalition structure was attained by the largest consistent set method and the stable set method. Furthermore, some insights were obtained. For example, stable coalition structures are equidistributed or approximate equidistributed; with supplier’s cost increasing, the size of the retailers’ coalition increases. Finally, the above conclusions are verified by numerical simulation. The results of this paper provide a reference for retailers’ coalition in a supply chain, such as automobile or Information Technology supply chain.     

A note on ‘trade-off and compatibility between performance: definitions and empirical evidence’

This paper improves on a novel methodology advanced in order to assess deterministically (i.e., precisely) compromises and compatibilities between manufacturing capabilities in individual firms. We extend the original proposal to include more recent theoretical developments arguing that both trade-offs and compatibilities (e.g., cumulative capabilities) can be observed in a relationship between two or more competitive criteria. This means that as opposed to widely-accepted views, trade-offs and compatibilities can be complementary, and not necessarily mutually exclusive, when explaining relationships between various competitive criteria. As such, our improved methodology and rationale can assess the existence of both trade-offs and compatibilities between multiple capabilities utilising a single framework. Opportunities for novel research that uses our methodology are also offered.     

A design model and a production–distribution and inventory planning model in multi-product supply chain networks

Supply chain network (SCN) design implicates decision-making at a strategic level. That includes selecting the right suppliers and determining the number and the location of plants, distribution centres and retailers. An apt design model of the supply chain is imperative for the proper function of the supply chain and consequently for making better operational decisions in an attempt of a continuous improvement. In this paper, we propose two models. The first model is a mixed-integer linear programming model which is concerned with the SCN design problem, whereas the second operational model is a mixed-integer non-linear programming model in respect to the production–distribution and inventory planning problem in a supply chain network. The number of customers and suppliers as well as their demand and capacities are assumed to be known in both models. Two steady-state genetic algorithms were implemented in MATLAB in order to solve both the design and the operational model. The results were compared with GAMS. Some examples were devised in order to demonstrate potential ways of use for the designer of the supply chain network, as well as for the supply chain manager.     

A note on “Modelling an industrial strategy for inventory management in supply chains: the ‘Consignment Stock’ case”

Braglia and Zavanella [2003, Modeling an industrial strategy for inventory management in supply chains: the ‘consignment stock’ care, International Journal of Production Research, 41 (16), 3793–3808] proposed an analytic formulation of consignment stock (CS) policy and made a comparison with Hill [1999, The optimal production and shipment policy for a single-vendor, single-buyer integrated production-inventory problem. International Journal of Production Research, 37 (11), 2463–2473] model. Through dividing per unit holding cost into a financial and a storage one the present note extends their conclusion and shows whether the CS model offers lower costs depends on the comparative result of buyer's and vendor's storage costs.     

A note on ‘Single-machine scheduling for minimizing total cost with identical,asymmetrical earliness and tardiness penalties’

We point out a flaw present in a recent publication, and show how methodology can be modified to correct it.     

A note on ‘beyond the trade-off and cumulative capabilities models: alternative models of operations strategy’

A recent thought provoking paper affirms that in practice, the trade-offs model is not used. In this study, we reanalyse the data based on a more complete understanding of Skinner’s model. Our results indicate that while there may be some evidence of firms that are capable of achieving high performance across a number of manufacturing capabilities in that investigation, there is also plenty of evidence generally consistent with the core tenet of the trade-offs model. We also emphasise that more practical and definitive statements about Skinner’s model must necessarily involve detailed studies of market leading firms, or, individual product/services. Opportunities to move forward on the topic of strategic trade-offs are outlined.     

Impact of the pull and push‐pull policies on the performance of a three‐stage supply chain

We investigate the performance of two common operating policies (i.e., pull and push‐pull) for a make‐to‐stock product in an un‐capacitated, three‐stage supply chain. The pull policy operates based on periodic orders received from the immediate downstream facility. However, in the push‐pull policy, while processes upstream of the order decoupling point are managed by the push policy, the downstream processes are managed by the pull policy. Simulation experiments are conducted to examine the impact of each operating policy under a variety of experimental conditions, characterised by demand uncertainty and lead‐time variability. Our results indicate that the relative advantage of the two policies is dependent on the type of uncertainty, the level of uncertainty, the inventory control policy and the performance measures of interest. More specifically, while the push‐pull policy results in lower inventory, the pull policy yields a better fill rate. This is in contrast to the notion that the pull policy generally results in superior inventory performance. Our findings suggest that firms should carefully consider the level of uncertainty, the inventory control policy and the performance measures of interest when determining the operating policy.