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1 – 10 of over 20000Scott R. Swenseth and Frank P. Buffa
This article provides a discussion of key components for thedecisionmaker concerned with the logistical issues of implementing aJust‐in‐Time (JIT) manufacturing philosophy. A JIT…
Abstract
This article provides a discussion of key components for the decisionmaker concerned with the logistical issues of implementing a Just‐in‐Time (JIT) manufacturing philosophy. A JIT philosophy promotes reduced cycle times that provide benefits not normally considered in traditional inventory models and presents new concerns for the purchasing and logistics functions. The ramifications are investigated of a JIT implementation using an inventory‐theoretic modelling procedure modified and expanded to incorporate these considerations. The resulting cost comparisons indicate that the lead time variability associated with uncertain transit times in JIT is critical in the determination of order cycle time, order point, safety stock and the holding cost of the safety stock.
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M. Caridi and R. Cigolini
This research provides a literature review in the field of uncertainty dampening methods for manufacturing systems, and proposes a new model to improve materials management…
Abstract
This research provides a literature review in the field of uncertainty dampening methods for manufacturing systems, and proposes a new model to improve materials management effectiveness in materials requirements planning environments. The literature review gives rise to a classification framework of the models along nine structural dimensions that refer to the safety buffer treatment, the environmental characteristics and the type of approach. On the basis of the classification framework, the proposed model provides guidelines for approaching the problem of dimensioning, positioning and managing safety stocks against demand uncertainty. The effectiveness of the proposed model has been tested by comparing it to the traditional approach, through a computer‐based simulation.
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In a Just‐in‐Time (JIT) environment, ideally there would be no need forsafety stocks. However, in practice, supply‐side and demandsideuncertainties cannot be completely…
Abstract
In a Just‐in‐Time (JIT) environment, ideally there would be no need for safety stocks. However, in practice, supply‐side and demandside uncertainties cannot be completely eliminated. Safety stocks would still be needed – particularly during the transition to JIT. Reviews the various methods for computing safety stocks. For each method, examines the relationship between safety stocks and lot sizes. The analysis indicates that the commonly used methods do not take into account the reduction in lot sizes that is characteristic of JIT. Such methods, therefore, are inappropriate for use in the JIT context.
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Cameron A. MacKenzie and Aruna Apte
The purpose of this paper is to quantify elements that make fresh produce supply chains (FPSCs) vulnerable to disruptions and to quantify the benefits of different…
Abstract
Purpose
The purpose of this paper is to quantify elements that make fresh produce supply chains (FPSCs) vulnerable to disruptions and to quantify the benefits of different disruption-management strategies.
Design/methodology/approach
This paper develops a mathematical model of a disruption in a FPSC and analyzes the relationships among variables.
Findings
The model determines the optimal safety stock as a function of the perishability of the produce, the length of time it takes to find the contamination, the level of demand during the disruption, and the amount of produce that can be rerouted. Applying the model to the 2006 E. coli spinach contamination reveals that the drop in customer demand for fresh spinach plays the largest role in Dole losing sales.
Research limitations/implications
The model includes several parameters that may be difficult to estimate. Future models can incorporate uncertainty that is inherent in supply chain disruptions.
Practical implications
The model in this paper can help a supply chain (SC) manager explore the trade-offs of different disruption-management strategies. For example, a SC manager can determine the value of holding additional safety stock vs trying to improve traceability in the SC.
Originality/value
This paper quantifies and models insights delivered in the qualitative analyses of FPSC disruptions. The theoretical contributions include an analysis of the interaction among safety stock, levels of demand, communication, and traceability parameters in order to help SC managers evaluate different strategies to mitigate the effects of contaminated produce.
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Patrik Jonsson and Stig-Arne Mattsson
The purpose of this paper is to explain the effects of inherent differentiation and system level performance assessment in inventory management. This is done by comparing the…
Abstract
Purpose
The purpose of this paper is to explain the effects of inherent differentiation and system level performance assessment in inventory management. This is done by comparing the performance of two common safety stock methods, by considering the methods’ inherent differentiation and item group-level performance effects.
Design/methodology/approach
Due to the lack of analytical relationships between the two methods, the analysis is based on event-driven simulations. Data are collected from eight different case companies. Findings explain the importance of assessing safety stock performance for groups of items and not for individual items, as is common in academic studies. It explains how the methods’ inherent differentiation and planning environment characteristics affect the relative performances of the two safety stock methods.
Findings
The study explains the importance of assessing performance of safety stock methods on a system-level, rather than on item-level measures. It explains why the demand fill-rate method has a negative impact on the performance for groups of items, while the number-of-days method has a positive impact. The study also explains how the group-level safety stock performance is affected by five demand data characteristics.
Research limitations/implications
The study explains the importance of assessing performance of safety stock methods on a system-level, rather than on item-level measures. It explains why the demand fill-rate method has a negative impact on the performance for groups of items, while the number-of-days method has a positive impact. The study also explains how the group-level safety stock performance is affected by five demand data characteristics.
Practical implications
Understanding the necessity of system level assessment of safety stock performance, how methods inherently differentiate service levels, and how demand characteristics affect methods’ performance can guide the choice of safety stock methods in companies.
Originality/value
No research on the characteristics of the number-of-days safety stock method, any assessment of differentiation characteristics of and comparison with the demand fill-rate method, has been published. The variable “inherent differentiation” is also introduced and defined.
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Srinivas Talluri, Kemal Cetin and A.J. Gardner
Managing inventories efficiently is a key factor for effective supply chain management. The area of inventory management has received significant attention in both academic and…
Abstract
Managing inventories efficiently is a key factor for effective supply chain management. The area of inventory management has received significant attention in both academic and practitioner fields. Several tools and techniques have been developed and applied for managing inventories across the entire supply chain in order to reduce costs and improve efficiency. This paper presents the application of a well‐established model for managing the made‐to‐stock inventories at a large multinational pharmaceutical company. The model effectively incorporates both demand and supply variability into the safety stock evaluations. A comparative analysis between the proposed and existing models is performed by utilizing data from four production plants and the resulting cost benefits are presented. The paper concludes with recommendations for managing the safety stocks of the company by discussing various strategic and operational policies.
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Narinder Kumar, Bikram Jit Singh and Pravin Khope
Inventory models are quantitative ways of calculating low-cost operating systems. These models can be either deterministic or stochastic. A deterministic model hypothesizes…
Abstract
Purpose
Inventory models are quantitative ways of calculating low-cost operating systems. These models can be either deterministic or stochastic. A deterministic model hypothesizes variable quantities like demand and lead time, as certain. However, various types of research have revealed that the value of demand and lead time is still ambiguous and vary unanimously. The main purpose of this research piece is to reduce the uncertainties in such a dynamic environment of Industry 4.0.
Design/methodology/approach
The current study tackles the multiperiod single-item inventory lot-size problem with varying demands. The three lot sizing policies – Lot for Lot, Silver–Meal heuristic and Wagner–Whitin algorithm – are reviewed and analyzed. The suggested machine learning (ML)–based technique implies the criteria, when and which of these inventory models (with varying demands and safety stock) are best fit (or suitable) for economical production.
Findings
When demand surpasses a predicted value, variance in demand comes into the picture. So the current work considers these things and formulates the proper lot size, which can fix this dynamic situation. To deduce sufficient lot size, all three considered stochastic models are explored exclusively, as per respective protocols, and have been analyzed collectively through suitable regression analysis. Further, the ML-based Classification And Regression Tree (CART) algorithm is used strategically to predict which model would be economical (or have the least inventory cost) with continuously varying demand and other inventory attributes.
Originality/value
The ML-based CART algorithm has rarely been seen to provide logical assistance to inventory practitioners in making wise-decision, while selecting inventory control models in dynamic batch-type production systems.
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Gustavo A. Vargas and Roger G. Dear
The effectiveness of alternative buffering strategies in complexmultilevel assembly manufacturing systems using the Material RequirementPlanning (MRP) methodology is explored and…
Abstract
The effectiveness of alternative buffering strategies in complex multilevel assembly manufacturing systems using the Material Requirement Planning (MRP) methodology is explored and assessed. The safety stock, safety lead time, “hard” safety capacity, and forecast inflation buffering strategies are tested under uncertainties of end‐item demand, resource supply, and task control. The MRP methodology is applied for scheduling along with a complex, realistic simulation model for execution of operations. Average inventory levels for end and component items, capacity utilisation, end‐item backorders and customer undersupport are used as performance measures. Experimental results establish safety stock and “hard” safety capacity as dominant buffering strategies under all uncertainty conditions, and task control is shown as the most disruptive uncertainty source.
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The log‐normal distribution provides a powerful decision tool for assessing the impact of marketing policies upon inventory allocations.
John Gattorna, Abby Day and John Hargreaves
Key components of the logistics mix are described in an effort tocreate an understanding of the total logistics concept. Chapters includean introduction to logistics; the…
Abstract
Key components of the logistics mix are described in an effort to create an understanding of the total logistics concept. Chapters include an introduction to logistics; the strategic role of logistics, customer service levels, channel relationships, facilities location, transport, inventory management, materials handling, interface with production, purchasing and materials management, estimating demand, order processing, systems performance, leadership and team building, business resource management.
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