Analysis of stability and bullwhip effect in production-inventory systems

To discuss the relationship between stability and bullwhip effect in the supply chain system,a basic model in a production-inventory control system is developed using difference equations.Z-transform techniques are applied to investigate the production ordering and inventory dynamics.For the two operational regimes of sufficient inventory coverage and insufficient inventory coverage,the scope of decision parameters which make the system stable or instable is investigated.Under two operational regimes and the actual system,production release rates,stability/instability and bullwhip effect in the stable region and instable region are examined based on different demand functions,and then the numerical simulation results are given.The results show that reasonable choices of fractional adjustment of inventory and supply line can make the system stable and decrease bullwhip effect.It is summarized that the piecewise linearization based on the stability analysis approach is a valid approximation to the analysis of production-inventory ordering systems with nonlinearities.Some interesting results are obtained and they have important implications for improving inventory and order decisions in supply chain systems.

Vendor managed inventory and bullwhip effect

This paper studies that the bullwhip effect of order releases and the amplifications of safety stock arise within the supply chain even when the demand model is ARIMA(0, 1, 1) and the forecast method used is a simple exponentially weighted moving average. It also examines a vendor managed inventory (VMI) program to determine how it can help alleviate such negative effects, and gives the theoretical proofs and numerical illustrations. The results show that the effects with VMI are better than the effect without VMI in demand forecasting and safety stock levels, etc.

Impact of Sophisticated Stationary Forecast Techniques on the Bullwhip Effect in a Supply Chain

The bullwhip effect in a multistage supply chain was analyzed using sophisticated stationary forecasts (third order moving average and third order exponential smoothing forecasts). The third order exponential smoothing and third order moving average forecasts sometimes have a variance reducing effect on the supply chain.In a supply chain with positively correlated or independent and identically distributed (i.i.d) demands, the order variance based on simple moving average forecast (or simple exponential smoothing forecast) is larger than the order variance based on second order moving average forecast (or second order exponential smoothing forecast),and the order variance based on second order moving average forecast( or second order exponential smoothing forecast) is larger than the order variance based on third order moving average forecast( or third order exponential smoothing forecast). In addition, for i.i.d demands, third order exponential smoothing forecast leads to a larger variation than third order moving average forecast.

Comparing the bullwhip effect under different inventory policies in engineering project supply chains

Measuring bullwhip effect is useful for making better controls on production planning and enhancing the supply chain operating efficiency.First,this article establishes the comparative analysis model of bullwhip effect between(s,S)and Periodic Review(PR)inventory policy based on the quantitative bullwhip effect model under different inventories.Then,the impacts of lead time,inventory review time,autocorrelation coefficient,and the number of samples on the gap of bullwhip effect under(s,S)and PR IP are analyzed.The results show that bullwhip effect in PR is more intense than(s,S)inventory policy.Contractors should pay more attention to control bullwhip effect when adopting PR inventory policy to enhance the total operating efficiency of the engineering project supply chains.

Applying IT to Avoid Bullwhip Effect of Supply Chain

Bullwhip effect is the most important factor considered in the supply chain management. It gets many scholars＇ attention that bullwhip effect has been restricting the development of the supply chain all the time. Information Technology （IT） can reduce bullwhip effect by sharing the information among the enterprises in the supply chain.

Study on the Complexity of the Bullwhip Effect

Recent years have witnessed a rapid growth of interest in the study of the dynamic behavior of replenishment rules of bullwhip effect. We prove that bullwhip effect and butterfly effect share a same the self-oscillation amplifying mechanism that is the ordering decisions the supplier self-oscillation amplify the perturbations brought by the errors in the processing of retailers' demand information. This results as an explicit self-similar structure of the sensitivity of the system to the initial values duty to the nonlinear mechanism. In this paper, the causes process of the bullwhip effect is described as the internal nonlinear mechanism and study on the complexity of bullwhip effect for order-up-to policy under demand signal processing. The methodology is based on fractal and chaotic theory and allows important insights to be gained about the complexity behavior of bullwhip effect.

A Study of the Bullwhip Effect for Short Life Cycle Products in Supply Chain Management

Shorter product life cycles present new dressed in supply chain literature. This research challenges to managing production and logistics not adequately adaddresses issues pertaining to the management of supply chains in a short life cycle environment. In this paper, we study the short life cycle environment; then we develop the ventory policy of the indirect manufacturer by explicitly using his demand us an output of the retailer＇s optimal inoptimal ordering policy. Finally, we also provide causes of the bullwhip effect in the context of short life cycle products.

Methods of vendor managed inventory control in supply chain management

By inducing the typical inventory control problem - the bullwhip effect, this paper presents vendor managed inventory (VMI) control methods on the basis of traditional methods of inventory management methods, constructs a VMI mathematics model, and analyzes the influence of VMI on inventory cost and channel profit. Finally, a special case is studied to verify that VMI is an effective supply chain strategy that can not only increase channel profit of supplier and customer but also improve full channel coordination, thereby reducing the bullwhip effect.

Causes of Restocking Delays in Absence of Real Time Inventory Tracking of Airtel Airtime

The purpose of this research was to ascertain causes of Restocking Delays in a Distributor Company of Airtel Airtime (AA) that give justification for benefits of using Real Time Inventory Tracking (R.T.I.T) in an attempt to mitigate Restocking Delays. From a study out at the Private Marketing and Trading Services (PMTS) an Authorized Distributor of Airtel Products undertaken in 2017 evidenced by Airtime scratch card and Electronic, E-Recharge Airtime among other forms to encourage R.T.I.T among other products in Telecom Companies and other Business Enterprises. The research comprises of the following areas among which included a detailed focus on a Qualitative and Quantitative approach in obtaining different categories of Restocking Delays in form of Themes and Sub Themes encountered in the Distribution Supply Chain (SC) of AA that is contained in this paper. This research continues to capture an in-depth explanation of the Managerial and Operational causes of restocking delays in respect to AA. Similarly, fast consumer products and services other than AA require a solution to Restocking Delays through implementation of Real Time Inventory Tracking Model (R.T.I.T.M) of AA among Distributor Companies (DCs). This paper also elaborated on Literature, Methodology and Findings obtained from the study. The results were obtained from regression analysis by using the Statistical Package for Social Sciences (SPSS) that showed a higher significance of Stock Turnover Period and Airtime Denomination as a contributor to Restocking Delays whereas Messages from Airtel Head office to the Distributor had a non-significant contribution to restocking Delays as in Figure 9. The research recommends a Model for R.T.I.T in Telecom Distribution SC of AA and Omnichannel Inventory Management (OIM) as a significant contributor to timely reliable inventory restocking and promotes higher sales among DCs and retailers through minimized Restocking Delays. It shows that the forces of Demand and Supply change over time with different tastes and preferences of customers. The imbalance in AA stock levels changes at given times due to unforeseen forces of consumer demand experienced by DCs, explained by the “Bullwhip Effect” due to information distortion in the Supply Chain (SC).

Risks and Uncertainty Analysis on International Logistics

With the development of globalization, more and more companies are under global operation. What coming with it, on one hand is chance and opportunity; on the other hand is risk and uncertainty. This paper aims to specify the potential and current risks and uncertainty that may be met in international logistics, then seeks some practical methods to dodge and solve them.

Coping with the Bullwhip Effect Using Inventory or Cash: An Environment-Behavior-Performance Paradigm

The bullwhip effect is w idely found in business and exerts adverse effects on business activities.To investigate the influence of the bullwhip effect on firm s'performance and their responses,this study proposed an environment-behavior-performance analysis fram ework and offered a new perspective for studying the bullwhip effect.Using data collected from 1,734 listed manufacturers in China from 2002 to 2017,we adopted regression models to test the proposed m odel and conducted a series of robustness tests.We find that the bullwhip effect is positively related to operating risk,inventory,and cash holdings,and the moderate levels of inventory and cash are negatively associated with operating risk.Specifically,inventory and cash play different roles and work together to alleviate operating risk induced by the bullwhip effect.However,excess resource holdings are positively associated with operating risk.Therefore,firm swith different levels of resources should hold suitable levels of inventory,cash,or both as contingent responses to the bullwhip effect.

STUDY ON THE CENTRALIZATION STRATEGY OF THE BLOOD ALLOCATION AMONG DIFFERENT DEPARTMENTS WITHIN A HOSPITAL

By far, the researches on how to distribute blood products among different departments in hospital have not been further studied, though the problem of blood shortage and wastage that caused by improper blood allocation is severe, which may endanger patient＇s lives and impose considerable costs on hospitals. In order to solve this problem, this paper mainly studies on how to distribute the blood items among different departments within a hospital and investigates the allocation approach with the novel management method by centralizing the inventory of several different departments. By integrating the blood inventory requirements of some departments, the hospital could reduce the rate of blood shortage and wastage effectively, release the pressure of the occupancy of resources and reduce the bullwhip effect of blood products. This paper illustrates the centralization principle in hospital and formulates the mixed integer programming model to work out the optimal allocation network scheme and the optimal inventory setting for every department. And the results of the numerical example demonstrate that this centralization method could considerably reduce blood shortage and wastage in hospital by about 72% and 90% respectively. Furthermore, it could decrease the total cost by about 108,540 RMB a month on blood supply chain management in the hospital and improve the effect of some certain surgeries by transfusing the fresh blood to patients.

The implications of blockchain-coordinated information sharing within a supply chain: A simulation study

The profitability of a supply chain(SC)is proportional to the stability of all its stakeholders as well as their consistent information sharing with an effective and efficient communication mechanism.Various inefficiencies,such as the bullwhip effect(BWE)and product unavailability,may be caused by a lack of coordination in an SC.The importance of sharing consumer demand has been quantified by comprehensive studies under the assumption that all SC participants will access the same information.However,only a few studies have studied the effect of minimal coordination or limited visibility of information while considering their effect on the overall efficiency of an SC.This work primarily leverages blockchain technology(BCT)to create a simulation model.To do this,an SC BWE-based model is initially developed.Following that,a blockchain-based robust information sharing system is simulated.Furthermore,information sharing is challenging,and SC stakeholders may not really trust each other and hence be reluctant to share sensitive information.Considering that,this paper propose an improved proof-ofauthority(PoA)consensus algorithm that will increase trust in a decentralized SC model.Multiple experiments are carried out to demonstrate the effectiveness of our approach,and the simulation results clearly demonstrate the effectiveness of information sharing in a supply chain via blockchain,as well as that trust between partners tends to increase overall SC efficiency and reduce BWE.