scholarly journals Adaptive inventory control system for material items with continuous non-stationary demand

2014 ◽  
Vol 5 (1) ◽  
pp. 11-20 ◽  
Author(s):  
Martin Krajčovič ◽  
Dariusz Plinta
Keyword(s):  
Control System ◽  
Inventory Control ◽  
Customer Service ◽  
Service Level ◽  
Inventory Systems ◽  
Inventory Level ◽  
Inventory Analysis ◽  
Software Module ◽  
Large Numbers ◽  
Customer Service Level

Abstract This paper describes an algorithm of dynamic inventory control system for large numbers of material items with continuous non-stationary demand. It uses principles of pull inventory control systems, statistical inventory analysis and joint replenishment inventory systems. This algorithm was processed in software module (VBA for Excel) and applied in practice. The target of described algorithm is to keep an optimum inventory level and optimum customer service level in terms of inventory control of items with non-stationary demand.

Dynamics analysis of a production-inventory control system with two pipelines feedback

Kybernetes ◽  
2017 ◽  
Vol 46 (10) ◽  
pp. 1632-1653
Author(s):  
Huthaifa AL-Khazraji ◽  
Colin Cole ◽  
William Guo
Keyword(s):  
Control System ◽  
Dynamic Model ◽  
Inventory Control ◽  
Production Control ◽  
Bullwhip Effect ◽  
Inventory Level ◽  
Content Type ◽  
Production Control System ◽  
Customer Service Level ◽  
Production Inventory

Purpose The purpose of this study is to propose a new dynamic model of a production-inventory control system. The objective of the new model is to maximise the flexibility of the system so that it can be used by decision makers to design inventory systems that adopt various strategies that provide a balance between reducing the bullwhip effect and improving the responsiveness of inventory performance. Design/methodology/approach The proposed production-inventory control system is modelled and analysed via control theory and simulations. The production-inventory feedback control system is modelled through continuous time differential equations. The simulation experiments design is conducted by using the state-space model of the system. The Automatic Pipeline Inventory and Order-Based Production Control System (APIOBPCS) model is used as a benchmark production-inventory control system. Findings The results showed that the Two Automatic Pipelines, Inventory and Order-Based Production Control System (2APIOBPCS) model outperforms APIOBPCS in terms of reducing the bullwhip effect. However, the 2APIOBPCS model has a negative impact on Customer Service Level. Therefore, with careful parameter setting, it is possible to design control decisions to be suitably responsive while generating smooth order patterns and obtain the best trade-off of the two objectives. Research limitations/implications This research is limited to the dynamics of single-echelon production-inventory control systems with zero desired inventory level. Originality/value This present model is an extension and improvement to Towill’s (1982) and John et al.’s (1994) work, since it presents a new dynamic model of a production-inventory control system which utilises an additional flow of information to improve the efficiency of order rate decisions.

Retail supply chain service levels: the role of inventory storage

2016 ◽  
Vol 29 (6) ◽  
pp. 887-902 ◽  
Author(s):  
Asif Salam ◽  
Farhad Panahifar ◽  
P.J. Byrne
Keyword(s):  
Supply Chain ◽  
Customer Service ◽  
Service Level ◽  
Retail Industry ◽  
Inventory Level ◽  
Content Type ◽  
Service Levels ◽  
Product Availability ◽  
Customer Service Level ◽  
The Relationship

Purpose In today’s competitive retail industry the most critical success factor is customer service which is indicated by product availability. It is argued that in the retail industry, product availability is an important measure of quality. The single most vital decision that every retailer needs to make is, how to maximize service level while keeping minimum inventory level. The purpose of this paper is to explain and demonstrate the relationship between inventory level and customer service level. Design/methodology/approach This study examines an inventory system utilizing a simulation model based on company data obtained from a retail fast-moving-consumer goods chain operating in Thailand. Findings The results suggest that the achievement of a responsive service level is dependent on managing an efficient supply chain in addition to logistics cost reductions. The findings also reveal the effect the inventory level has on the service level. From the findings of this study, demand variability and service level have been found to have the most significant influence on the inventory level. From the findings, it can also be shown that real and accurate information is very important for service supply chains. Practical implications The paper promotes the importance of having an appropriate inventory management policy for a retail chain which should be driven by retail companies in order to better balance inventory and service levels. Originality/value The relationship between the inventory level and customer service level lead to different outcomes at different combinations of inventory and service levels. Significant relationships were found between inventory and service levels.

scholarly journals Service-oriented performance of inventory models with partial information on unimodal demand lead-time distributions

2020 ◽  
Author(s):  
Gerrit K. Janssens ◽  
Lotte Verdonck ◽  
Katrien Ramaekers
Keyword(s):  
Customer Service ◽  
Lead Time ◽  
Partial Information ◽  
Service Level ◽  
Inventory Level ◽  
Worst Case ◽  
Point Distribution ◽  
Safety Stock ◽  
Demand Distribution ◽  
Customer Service Level

Facing uncertainty in demand, companies try to avoid stock-outs by holding safety inventories, depending on a pre-set customer service level. The knowledge of the demand distribution during lead-time serves to determine the safety inventory level. Many times the distribution is not fully known, except maybe for its range, mean or variance. However literature shows that the performance of holding safety stock strongly depends on the characteristics of the distribution. One option is to protect against the worst case distribution given some information like range or moments. But this worst case is a two-point distribution, bringing unbelief to managers that such an occurrence would ever appear. Mostly they share the opinion that the demand distribution is unimodal. This research develops a technique to derive the safety stock for unimodal demand distributions of which the mode either is known or can be estimated. In this way, the managers obtain solutions to the decision problem including a higher belief that the related type of distribution might appear in practice.

What should be lean buffer threshold for the forward-reserve warehouse?

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Bhavin Shah
Keyword(s):  
Mathematical Model ◽  
Customer Service ◽  
Value Added ◽  
Service Level ◽  
Buffer Size ◽  
Value Stream Mapping ◽  
Content Type ◽  
Customer Service Level ◽  
The Impact ◽  
Just Right

PurposeThe assorted piece-wise retail orders in a cosmetics warehouse are fulfilled through a separate fast-picking area called Forward Buffer (FB). This study determines “just-right” size of FB to ensure desired Customer Service Level (CSL) at least storage wastages. It also investigates the impact of FB capacity and demand variations on FB leanness.Design/methodology/approachA Value Stream Mapping (VSM) tool is applied to analyse the warehouse activities and mathematical model is implemented in MATLAB to quantify the leanness at desired CSL. A comprehensive framework is developed to determine lean FB buffer size for a Retail Distribution Centre (RDC) of a cosmetics industry.FindingsThe CSL increases monotonically; however, the results concerning spent efforts towards CSL improvement gets diminished with raised demand variances. The desired CSL can be achieved at least FB capacity and fewer Storage Waste (SW) as it shifts towards more lean system regime. It is not possible to improve Value Added (VA) time beyond certain constraints and therefore, it is recommended to reduce Non-Value Added (NVA) order processing activities to improve leanness.Research limitations/implicationsThis study determines “just-right” capacity and investigates the impact of buffer and demand variations on leanness. It helps managers to analyse warehouse processes and design customized distribution policies in food, beverage and retail grocery warehouse.Practical implicationsProposed buffering model offers customized strategies beyond pre-set CSL by varying it dynamically to reduce wastages. The mathematical model deriving lean sizing and mitigation guidelines are constructive development for managers.Originality/valueThis research provides an inventive approach of VSM model and Mathematical algorithm endorsing lean thinking to design effective buffering policies in a forward warehouse.

Multi-objective particle swarm optimisation approach for production-inventory control systems

2018 ◽  
Vol 13 (4) ◽  
pp. 1037-1056 ◽  
Author(s):  
Huthaifa AL-Khazraji ◽  
Colin Cole ◽  
William Guo
Keyword(s):  
Control System ◽  
Control Systems ◽  
Inventory Control ◽  
Dynamic Performance ◽  
Particle Swarm ◽  
Particle Swarm Optimisation ◽  
Inventory Level ◽  
Content Type ◽  
Multi Objective ◽  
Production Inventory

Purpose This paper aims to optimise the dynamic performance of production–inventory control systems in terms of minimisation variance ratio between the order rate and the consumption, and minimisation the integral of absolute error between the actual and the target level of inventory by incorporating the Pareto optimality into particle swarm optimisation (PSO). Design/method/approach The production–inventory control system is modelled and optimised via control theory and simulations. The dynamics of a production–inventory control system are modelled through continuous time differential equations and Laplace transformations. The simulation design is conducted by using the state–space model of the system. The results of multi-objective particle swarm optimisation (MOPSO) are compared with published results obtained from weighted genetic algorithm (WGA) optimisation. Findings The results obtained from the MOPSO optimisation process ensure that the performance is systematically better than the WGA in terms of reducing the order variability (bullwhip effect) and improving the inventory responsiveness (customer service level) under the same operational conditions. Research limitations/implications This research is limited to optimising the dynamics of a single product, single-retailer single-manufacturer process with zero desired inventory level. Originality/value PSO is widely used and popular in many industrial applications. This research shows a unique application of PSO in optimising the dynamic performance of production–inventory control systems.

scholarly journals A literature review on multi-echelon inventory management: the case of pharmaceutical supply chain

2018 ◽  
Vol 200 ◽  
pp. 00013 ◽  
Author(s):  
Nouçaiba Sbai ◽  
Abdelaziz Berrado
Keyword(s):  
Supply Chain ◽  
Customer Service ◽  
Inventory Management ◽  
Raw Materials ◽  
Integrated Approach ◽  
Service Level ◽  
Pharmaceutical Products ◽  
Management Problem ◽  
Pharmaceutical Supply Chain ◽  
Customer Service Level

Inventory management remains a key challenge in supply chain management. Many companies recognize the benefits of a good inventory management system. An effective inventory management helps reaching a high customer service level while dealing with demand variability. In a complex supply chain network where inventories are found across the entire system as raw materials or finished products, the need for an integrated approach for managing inventory had become crucial. Modelling the system as a multi-echelon inventory system allows to consider all the factors related to inventory optimization. On the other hand, the high criticality of the pharmaceutical products makes the need for a sophisticated supply chain inventory management essential. The implementation of the multi-echelon inventory management in such supply chains helps keeping the stock of pharmaceutical products available at the different installations. This paper provides an insight into the multi-echelon inventory management problem, especially in the pharmaceutical supply chain. A classification of several multi-echelon inventory systems according to a set of criteria is provided. A synthesis of multiple multi-echelon pharmaceutical supply chain problems is elaborated.

scholarly journals Multi-objective optimization model of waste tire recycling network

2020 ◽  
Vol 214 ◽  
pp. 03052
Author(s):  
Bin Wang ◽  
HeHua Li
Keyword(s):  
Environmental Protection ◽  
Customer Service ◽  
Service Level ◽  
Decision Variable ◽  
Multi Objective ◽  
Waste Tire ◽  
Multi Objective Programming ◽  
Customer Service Level ◽  
Logistics Enterprises ◽  
Waste Tire Recycling

To achieve sustainable development, logistics enterprises need not only to reduce costs, but also to save energy for environmental protection and improve customer service level. The improvement of reverse logistics management level of waste tires is of great significance to improve the efficiency of the automobile industry. In this paper, multi-objective programming is adopted to establish the waste tire recycling network model. The decision variable is whether the network nodes are set or not, the traffic flow between nodes. Constraints include meeting customer demand, balance of flow in and out of logistics nodes, etc. The model is solved by ε- constraint. Taking the actual data of the enterprise as an example, the operation results show that the operation cost, carbon emission and customer transportation distance can get an consistence within a certain range. Waste tire logistics enterprises can realize the simultaneous improvement of profit, environmental protection and customer service level.

Comparative multi criteria analysis and dependent optimisation through integrated supply chain

2014 ◽  
Vol 63 (8) ◽  
pp. 1046-1069 ◽  
Author(s):  
Sanjay Sharma ◽  
Akshat Sisodia
Keyword(s):  
Supply Chain ◽  
Lead Time ◽  
Service Level ◽  
Inventory Level ◽  
Inventory Policies ◽  
Inventory Cost ◽  
Content Type ◽  
Customer Service Level ◽  
Integrated Supply Chain ◽  
Different Levels

Purpose – The purpose of this paper is to compare various inventory policies and their effect on various performance metrics at different levels of a multi stage supply chain. Later the model is integrated to include optimization of entire supply chain through implementation of collaborative supply chain model. Design/methodology/approach – Alternative inventory policies have been developed at different echelons and a comparison reflecting the usability on various factors such as inventory level, inventory cost and service level is presented so as to support the decision-making process. Various inventory policies such as economic order quantity, periodic ordering (T, M) and stock to demand have been considered. Along with the basic assumptions; lead time, demand variability, variability in demand during lead time, stock out costs have also been included to make the model more applicable to practical situations. Findings – After the selection of most appropriate inventory policy at each level through a decision matrix, the total cost of operating such a supply chain is calculated along with other parameters such as service level and inventory turns. The approach is of aggregating the optimized value at each echelon referred to as aggregated supply chain in the paper. Then the concept of integrated supply chain is introduced which optimizes the supply chain as a whole, rather than aggregating local optima. The comparison is made between the two approaches that prove the integrated supply chain's superiority. Furthermore, dependent optimization is run as it is not practically possible for each echelon to optimize at the same time. Originality/value – Each echelon is allowed to optimize at a time and other echelons assume corresponding values. This final comparative multi criterion analysis is based on the three factors, i.e. inventory cost, customer service level and inventory turnover with different weights assigned to each factor at different levels of a supply chain. Finally a consolidation of results is made to reflect the overall preference which proves that an integrated supply chain best serves all the parameters combined together.

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