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.     

Flexible kanbans to enhance volume flexibility in a JIT environment: a simulation based comparison via ANNs

Kanbans play an important role in the information and material flows in a JIT production system. The traditional kanban system with a fixed number of cards does not work satisfactorily in an unstable environment. In the flexible kanban-type pull control mechanism the number of kanbans is allowed to change with respect to the inventory and backorder level. Based on the need for the flexible kanban, a method was proposed by (Husseini, S.M.M., O’Brien, C., and Hosseini, S.T., 2006. A method to enhance volume flexibility in JIT production control. International Journal of Production Economics, 104 (2), 653–665), using an integer linear programming technique, to flexibly determine the number of kanbans for each stage of a JIT production system, minimising total inventory cost for a given planning horizon. Here, the effectiveness of the method proposed by Husseini et al. is examined by a case study and compared with the results for the conventional method of fixed kanban determination. This is also confirmed by a simulation study using artificial neural networks (ANNs). The main aim of this paper is to show the cost advantage for Husseini et al.'s method over the conventional method in fluctuating demand situations, and especially to prove that simulation via ANNs ensures a simplified representation for this method and is time saving.     

Pricing decisions in a strategic single retailer/dual suppliers setting under order size constraints

In this paper, we study a duopolistic market of suppliers competing for the business of a retailer. The retailer sets the order cycle and quantities from each supplier to minimize its annual costs. Different from other studies in the literature, our work simultaneously considers the order size restriction and the benefit of order consolidation, and shows non-trivial pricing behaviour of the suppliers under different settings. Under asymmetric information setting, we formulate the pricing problem of the preferred supplier as a non-linear programming problem and use Karush–Kuhn–Tucker conditions to find the optimal solution. In general, unless the preferred supplier has high-order size limit, it prefers sharing the market with its competitor when retailer’s demand, benefit of order consolidation or fixed cost of ordering from the preferred supplier is high. We model the symmetric information setting as a two-agent non-zero sum pricing game and establish the equilibrium conditions. We show that a supplier might set a ‘threshold price’ to capture the entire market if its per unit fixed ordering cost is sufficiently small. Finally, we prove that there exists a joint-order Nash equilibrium only if the suppliers set identical prices low enough to make the retailer place full-size orders from both.     

23500m~3/h空分设备两种液体增产工况的比较

为了实现低成本增加空分设备的液体产量,在同型号的2套23500 m3/h空分设备上进行了空气膨胀和氮气膨胀两种液体生产工况的比较,并得出各自较经济的运行场合。简介两种液体增产工况的流程和相应参数,对比分析了两种液体增产工况下的液氧增加量和增加液氧的单位能耗,最后总结两种液体增产工况的优缺点。     

Revising the master production schedule in a HPP framework context

This paper investigates the stability of the master production schedule (MPS) in a multi-product batch chemical plant, a typical example of manufacturing plants in the process industry. The effects of demand pattern, replanning periodicity, setup costs and unit production cost on the performance of the MPS in a rolling horizon situation are examined. Adopting the hierarchical production planning framework, a two-level mathematical model is developed to conduct the study. A comprehensive simulation work and statistical analyses are reported in this work. The results of the study show that replanning periodicity significantly influences the scheduling instability and the impact of setup cost on scheduling instability is dependent on the demand pattern and the unit production cost. Moreover, the findings indicate that replanning frequency does not affect the total cost of the system if the cost structures are not extreme. Finally, the results show that cost structures affect the batching of orders (converting production quantities into an optimal number of batches to be processed).     

Cost–volume–profit analysis under uncertainty: a model with fuzzy estimators based on confidence intervals

In this paper we express the uncertainty existing in cost–volume–profit analysis via a new method that constructs fuzzy estimators for the parameters of a given probability distribution function using statistical data. First we present a fuzzy function for the cost and we search for the optimal solution among alternatives as Finch and Gavirneni [2006, International Journal of Production Research, 44 (20), 4329–4342] do, but here we use fuzzy estimators for the variable costs. As a consequence, we formulate a fuzzy number that represents the difference between the costs of the alternatives. Furthermore, we consider conditions of ‘complete’ uncertainty when a company needs to choose between two products and we express the profits and the risk via fuzzy estimators. Finally, under the same conditions of uncertainty we express the breakeven point when the income equals the total cost.     

Economic lot sizing for an imperfect production system subject to random breakdowns

This article considers an economic manufacturing quantity model for an imperfect production process that is subject to random machine breakdowns. The product is manufactured intermittently in batches to meet a constant demand. During a production run, the system is assumed to deteriorate over time. As a result, a fixed proportion of items produced are defective. The system is also subject to random breakdowns. A no-resumption inventory control policy is adopted. Under this policy, the production run is aborted when a breakdown occurs. Production will be resumed only when all on-hand inventories are depleted. Corrective maintenance is carried out immediately after a breakdown. The time-to-shift and the time-to-breakdown are two random variables following different exponential distributions. The objective is to find an optimal production lot size that minimizes the expected (long-run) total cost per unit time. Several models are investigated and a numerical approach is developed to obtain an optimal production lot size.     

Conserving energy by optimizing the heat exchanger networks of glyphosate production with pinch technology

China is one of the largest glyphosate producers in the world. The production process consumes a large amount of energy and discharges a huge volume of wastewater. In the glyphosate production system, the by-product recovery process consumes the largest amount of energy. To conserve energy consumption and minimize wastewater discharge, the study applies pinch technology to optimize the heat exchanger network of the by-product recovery subsystem. The results show that the optimal temperature for the process is 8°C. Theoretically, the optimized heat exchanger network has the potential to reduce the annual consumption of steam, condensed water, and the freshwater resource by 1.53, 26.84 and 56.72%, respectively, when compared with current consumption levels. At the same time, the total annual cost can be reduced by 100,000 dollars per year, which means that the optimization can achieve the win–win objective of the economic and environmental benefits in the glyphosate production process.     

The economic lot and delivery scheduling problem: common cycle, rework, and variable production rate

The economic lot and delivery scheduling problem is to simultaneously determine the production sequence of several assembly components at a supplier and the delivery interval of those components to the customer. The customer, an assembly facility, is assumed to use the components at a constant rate. The objective is to find the production sequence and delivery interval that minimize the holding, setup, and transportation cost for the supply chain. Previous solutions to the problem assume a constant production rate for each component and that all components are of acceptable quality. These assumptions ignore volume flexibility and quality cost. Volume flexibility permits a system to adjust the production rate upwards or downwards within wide limits. Also, component quality may deteriorate with larger lot sizes and decreased unit production times. In this paper, we develop an algorithm for solving the economic lot and delivery scheduling problem for a supplier using a volume flexible production system where component quality depends on both lot sizes and unit production times. We test the performance of the algorithm and illustrate the models with numerical examples.     

Comments on ‘vendor-managed inventory with consignment stock agreement for single vendor–single buyer under the emission-trading scheme’

Zanoni, Mazzoldi, and Jaber [Zanoni, S., L. Mazzoldi, and M. Y., Jaber. 2014. Vendor-managed inventory with consignment stock agreement for single vendor–single buyer under the emission-trading scheme. International Journal of Production Research 52 (1): 20–31] consider a joint economic lot size problem under the vendor-managed inventory with consignment stock agreement and an emission-trading scheme. They show that the total cost of the system is a jointly convex function by simply showing that every element of the Hessian is positive. Noticing this mistake, we analyse the same problem in this technical note. We first provide a closed-form solution when the production rate is given. In order to avoid a complete search over all possible production rates, we then develop an efficient continuous approximation algorithm. Computational experiment shows that the approximation algorithm is effective and efficient.     

Production and Distribution Lot Sizing in a Two Stage Supply Chain

We develop a two stage model of a manufacturing supply chain. This two stage production transportation model features capacitated production in two stages, and a fixed cost (or concave cost) for transporting the product between the stages. We prove several properties of this model, which we call the Two Stage Production Distribution Problem (2SPDP) model. By placing "non-speculative" assumptions on production and transportation, we show that our model reduces to a related model, with one capacitated production stage with linear production cost, and transportation between two inventory locations with non-linear transportation cost. Finally, we present polynomial algorithms for this model under several different transportation cost structures and capacity assumptions.     

Comment on ‘Technical Note – Reaching more states for control of FMS’

Uzam and Zhou (Uzam, M. and Zhou, M., 2006. An improved iterative synthesis method for liveness enforcing supervisors of flexible manufacturing systems. International Journal of Production Research, 44 (10), 1987–2030) were able to obtain a near optimal controlled model for the net S³PR with 21,562 good states. Chao's deadlock recovery scheme (Chao, D.Y., 2010. Technical Note – Reaching more states for control of FMS. International Journal of Production Research, 48 (4), 1217–1220) improves by reaching more states (21,585). However, this paper identifies a problem and proposes a solution.     

The Simultaneous Determination of Plant and Leased Warehouse Capacities for a Firm Facing Uncertain Demand in Several Regions

For each of several regions a firm has forecasted a probability distribution of future annual demand, and the plan is to build a single production facility to serve this demand. Each region is served by a simple leased warehouse with a lease cost which is a linear function of capacity. Any regional demand exceeding warehouse capacity is lost. The cost of building the plant is a nonlinear function of its capacity, and the unit cost of producing the product and supplying it to a region is constant. We develop an efficient algorithm based on the Kuhn-Tucker conditions for simultaneously determining the plant and warehouse capacities which will maximize the firm's expected profit. The paper includes a numerical example demonstrating the use of this algorithm.     

Economic batch quantity in a multi-stage production system

A mathematical model has been developed in this paper for determining the total annual variable cost for a product which requires processing on a number of production stages. The demand for the product is assumed uniform over time and it is manufactured in equal lot sizes. In order to minimize the manufacturing cycle time of o production lot, the movement of the items between production stages is in sub-batches of equal sizes, As a result of manufacturing a production lot in sub-batches, the following additional costs are incurred: (1) additional cost of stock holding for process inventory; (2) cost of transporting sub-batches; (3) cost of multiple set-ups. A simple method is then adopted for minimizing the total annual variable cost of the multistage production system. An example has been solved to illustrate the method.     

Production projects – designing and operating lifecycle-oriented and flexibility-optimized production systems as a project

Due to fast changing markets and ever shorter product lifecycles, lifecycle-orientation and flexibility can be described as major factors for success. As an answer to the resulting challenges this paper introduces the concept of Production Projects. According to the concept either a single production line or an entire production location can be planned and operated as a project. Thereby, Production Projects form the organizational base to link the lifecycles of products and production systems and to optimize the degree of flexibility of the latter. Within Production Projects the traditional project target dimensions?‘quality’,?‘time’?and?‘cost’?are supplemented by?‘flexibility’?as a fourth target dimension. Major elements within the concept are the so-called Production Project Master Schedule, Process Modules, and the Flexibility Mode and Effect Analysis (FlexMEA). The Production Project Master Schedule consists of standardized phases for the lifecycle-oriented design and operation of a production system. Based on the Master Schedule, the standardized building blocks of a production system, so-called Process Modules, can be relocated within and in between production locations. With the FlexMEA, an innovative method is introduced, which enables an enterprise to plan and monitor the degree of flexibility of its production systems and to derive flexibility optimizing measures if necessary.     

Economic Design of CSP-1 Plan Under the Dependent Production Process and Linear Inspection Cost

Chen and Chou presented the economic design of type I continuous sampling plan (CSP-1 plan) under the linear inspection cost. However, it can be argued that the production process is seldom independent. In this paper, we further propose the problem concerning the economic design of CSP-1 plan under the dependent production process and linear inspection cost. A solution procedure is developed to find the unique combination (i*, f*) that will meet the average outgoing quality limit (AOQL) requirement while also minimizing the total expected cost per unit produced during one inspection cycle.     

Pieces of the Past: Early Photomontage and the Voice of History

A key dimension of photomontage is the way that its formal features – and consequent debates about the probity of making a photograph out of multiple sources – illuminate some of the fundamental problems of representation in the late nineteenth century. Among these was the question of whether an account of the past was properly presented as an unmediated transmission of fact, or demonstrably fashioned by an author: whether the tools of representation were to be submerged or emphasised. This article examines the parallels between the strategies of authorial visibility in early photomontage and the rhetorical approaches adopted by historians to modulate their presence in their texts. In particular, this study investigates the convergences of historiography and photomontage around the collapse of the Second Empire, a moment that witnessed powerful shifts in the conception of the voice of the historian as well as the production of photomontages that grappled with – and even thematised – the problem of their constructedness. An important but little-known group of photomontages by Eugène Appert, depicting the Imperial family in exile as well as the emerging Third Republic from which they fled, registers these conjunctions in their full complexity.     

A new multi-objective optimization method for master production scheduling problems using simulated annealing

Tactic planning or master production scheduling focuses on time and spatial decomposition of the aggregate planning targets and forecasts, as well as, forecast and provision of needed resources. This process becomes extremely hard and time consuming with the increase of number of products, resources and periods considered. In face of such obstacles, this work shows a study of an Artificial Intelligence technique called Simulated Annealing applied to the optimization of production planning problem, more specifically, Master Production Scheduling. This work reviews some of the fundamental theory of simulated annealing, the methodology for master production scheduling calculation, the applicability of simulating annealing to planning problems, most important results and suggestions for further studies.     

Reliability-based maintenance and job scheduling for identical parallel machines

Quality has an important role in manufacturing, and on the other hand, machine condition has a significant effect on quality. Based on this fact, all manufacturers integrate the production scheduling with maintenance activities to keep the machines in perfect conditions. In this paper, we propose a mixed integer nonlinear model to optimise the quality cost, maintenance cost, earliness–tardiness cost and interruption cost simultaneously. We assume that if machines work in undesirable conditions, their quality is reduced, resulting in quality cost. On the other hand, if the machines are repaired to decrease the quality cost, maintenance cost and other cost such as earliness–tardiness cost and interruption cost are imposed to the manufacturer. Several numerical instances are implemented by the proposed model to show the model effectiveness to obtain the best maintenance and production scheduling with minimum quality cost.     

Analysis of Strain and Stress in Ceramic,Polymer and Metal Matrix Composites by Raman Spectroscopy

Raman scattering is a unique tool providing information on the structure and short‐range order of matter. Stress‐induced Raman shifts can be used to determine the stress/strain in films, fibres, particulate composites and, more generally, in any phase a few microns or more in scale. Quantitative results follow from a wavenumber calibration as a function of tensile strains or pressures applied to reference fibres or crystals. Furthermore, if the material is coloured, (near) resonant Raman scattering occurs, which enhances the scattered light intensity and simplifies the spectra – especially for harmonics – but drastically reduces the analysed volume (in‐depth penetration ∼10–100 nm). This paper discusses the effective and potential advantages/drawbacks of Raman micro‐spectrometry technique. The procedures to improve the sensitivity, the legibility and the reliability will be addressed. Examples will be chosen among (aramid, C, SiC) fibre‐ reinforced ceramic (CMCs), polymer (PMCs) or metal matrix (MMCs) composites.