Dissertations / Theses on the topic 'Bullwhip Effect'
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O'Donnell, Tina. "Supply chain optimisation : reducing the bullwhip effect." Thesis, University of Ulster, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.435603.
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Dahlin, Klara, and Oscar Säfström. "Causes of the bullwhip effect : A study of the bullwhip effect in the Volvo Group Service Market Logistics’ supply chain." Thesis, Linköpings universitet, Logistik- och kvalitetsutveckling, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-177968.
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The bullwhip effect is defined as an upstream amplification of demand variability and has received interest within multinational companies for decades. As early as in the 1950’s, Forrester (1958) discussed what is today known as the bullwhip effect, which has a negative impact on the customer service, costs, and inventory investment in a supply chain (Lee et al., 1997). Even though the bullwhip effect has been noticed in various industries, the consequences, in form of decreased availability and increased costs the further up the supply chain the bullwhip goes, still remain. The employees at Volvo Group Service Market Logistics suspect that their supply chain has been affected by the bullwhip effect and want to know if it is correct and subsequently know why it has occurred. Therefore, this master’s thesis highlights the root causes of the bullwhip effect and presents strategies to mitigate it. To understand how the bullwhip effect affected the Volvo Group Service Market Logistics’ supply chain, the purpose was formulated as follow: The purpose of this study is to identify events in the Volvo Group Service Market Logistics’ supply chain where the bullwhip effect has occurred, its root causes, and how to reduce or eliminate the bullwhip effects. The studied flow was from the Central Distribution Center (CDC) in Ghent, to the Regional Distribution Center (RDC) in Brazil, to the Dealers associated to the RDC in Brazil, and the customers. Data was collected from each node and events were studied to find bullwhip events. After sorting out the part numbers that passed the criteria for bullwhip events, the amount of data had to be reduced even more. A couple of different conditions were applied which resulted in four suitable bullwhip events. Thereafter, the authors conducted interviews with Logistics Managers at each node of the supply chain to find the root causes of the bullwhip effect in each studied event. Among the several found root causes, lack of information transparency was the most frequent occurring root cause, found in three out of four studied bullwhip events. Insufficient communication and lack of information sharing cause bullwhip effects, and the authors found that improved communication both between and within the nodes will contribute to better planning, and consequently avoided bullwhip effects. Other root causes found were issues with the ordering system, lack of learning and experience, neglected lead times, fear of empty stock, price fluctuations, and phase-out of the spare part. To reduce or eliminate the bullwhip effect, the focus was on mitigating the root causes since the root causes create opportunities for the bullwhip effect to occur. Four suggestions were given with suitable mitigation strategies found in the literature, where the four suggestions were sales campaigns, prepare for boosts, keep track of manually placed orders, and ordering system and Logistics Manager behavioural issues. The suggestions could then be connected to the different found root causes. The stated suggestions and mitigation strategies focused on mitigating the root causes in a long-term perspective and consequently the bullwhip effect itself.
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Iyer, Harikumar, and Saurabh Prasad. "Statistical process control approach to reduce the bullwhip effect." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/40105.
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Thesis (M. Eng. in Logistics)--Massachusetts Institute of Technology, Engineering Systems Division, 2007.Includes bibliographical references (leaves 66-68).
The bullwhip effect is a pervasive problem in multi echelon supply chains that results in inefficient production operations and higher inventory levels. The causes of the bullwhip effect are well understood in industry and academia. Quantitative and qualitative solutions to attenuate this effect have been proposed in various research studies. In this research a quantitative solution in the form of a Statistical Process Control (SPC) based inventory management system is proposed that reduces the bullwhip effect while reducing inventory without compromising service level requirements for a variety of products. The strength of this methodology is in its effectiveness in reducing bullwhip for fast moving products in the mature phase of their lifecycles where improving production efficiency and lowering inventory investment are critical. However, fill rate issues are observed for slow moving products and therefore, the methodology is not recommended for such products. Finally, the application of this methodology to reduce the bullwhip effect is illustrated for a product family of a medical devices company. The results for the different classes of products in this family are discussed.
by Harikumar Iyer [and] Saurabh Prasad.
M.Eng.in Logistics
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Villegas, Morán Felipe Antonio. "Supply chain dynamics, structural causes of the bullwhip effect." Thesis, University of Manchester, 2005. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.564143.
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Wangphanich, Pilada Mechanical & Manufacturing Engineering Faculty of Engineering UNSW. "A simulation model for quantifying and reducing the bullwhip effect." Publisher:University of New South Wales. Mechanical & Manufacturing Engineering, 2008. http://handle.unsw.edu.au/1959.4/43272.
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Over the past of decade, the bullwhip effect has increasingly become a popular topic for researchers and practitioners in the area of supply chain management since it negatively influences cost, inventory, reliability and other important business processes in supply chain agents. Although there are many remedies for the bullwhip effect summarised in existing literature, it still occurs in several industries. This is partly because it is difficult to apply the results from existing research which analyse the bullwhip effect mainly in a simple supply chain. In addition, several tools and methodologies developed are used for analysing the bullwhip effect in a simple supply chain with several constraints. Therefore, this research aims to develop a unique simulation approach based on system dynamics modelling and Adaptive Network Based Fuzzy Inference System (ANFIS) for quantifying and reducing the bullwhip effect in a multi-product, multi-stage supply chain. System dynamics modelling which is a powerful simulation approach for studying and managing complex feedback system was selected as a main tool in this research. In addition, ANFIS was implemented in system dynamics modelling in order to increase the reliability of a system dynamics model for modelling soft variables. The proposed model covers variables influencing the bullwhip effect which are the structure of supply chain network, supply chain contributions and supply chain performances. As a result, a two layer simulation with three generic models was developed. The flexibility of this proposed model is the ability to model various types of ordering policies which are basic inventory policies, Material requirement planning (MRP) system and Just in time (JIT) approach. Three actual manufacturing supply chains were used as case studies to validate and demonstrate the flexibility of the model developed in this research. This model satisfactorily quantifies the bullwhip effect and the bullwhip effect levels identified in these case studies are significantly decreased by using the proposed simulation model. The successful results indicate that the model can be a useful alternative tool for supply chain managers to quantify and reduce the bullwhip effect in multi-product, multi-stage supply chains.
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Qu, Zhan, and Horst Raff. "Centralized versus Decentralized Inventory Control in Supply Chains and the Bullwhip Effect." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-229867.
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This paper constructs a model of a supply chain to examine how demand volatility is passed upstream through the chain. In particular, we seek to determine how likely it is that the chain experiences a bullwhip effect, where the variance of the upstream firm’s production exceeds the variance of the downstream firm’s sales. We show that the bullwhip effect is more likely to occur and is greater in size in supply chains in which inventory control is centralized rather than decentralized, that is, exercised by the downstream firm.
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Tambat, Abhishek Ramesh. "Prediction and prevention of the bullwhip effect in replenishment supply chains." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/117942.
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Thesis: M.B.A., Massachusetts Institute of Technology, Sloan School of Management, in conjunction with the Leaders for Global Operations Program at MIT, 2018.Thesis: S.M., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, in conjunction with the Leaders for Global Operations Program at MIT, 2018.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 65-66).
Nikes replenishment supply chain stages finished goods and materials at distribution centers and factories to provide short replenishment lead times to customers. Make-to-stock supply chains are particularly susceptible to the risks of the bullwhip effect, where demand information is distorted as it is transmitted up the chain from customers to suppliers. The information distortion leads to a sub-optimal capacity planning and inventory allocation that leads to stock-outs or excess inventory. While the literature on bullwhip analysis is rich, most of the prior work is developed based on simplistic assumption of a single stage supply chain model with only one product. These simplistic models fail to address challenges and identify relevant parameters in a complex supply chain with thousands of SKUs. Further the simplistic analysis fails to change the underlying behavior that causes bullwhip in the first place. In this work, we address all above challenges in three steps. First, we understand the inventory ordering model and the process map to identify the relevant indicators. Second, through pattern recognition, the inventory ordering patterns are clustered in three groups. We develop a hierarchical decision tree model that isolates the statistically significant features for the bullwhip effect. Finally, we team up with the stakeholders to guide their behavior towards mitigating the bullwhip effect.
by Abhishek Ramesh Tambat.
M.B.A.
S.M.
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Peng, Ronghe, and Yi Xiao. "How to manage the bullwhip effect in the supply chain : A case study on Chinese Haier Group." Thesis, Högskolan i Gävle, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-16288.
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This thesis intended to increase the understanding of bullwhip effect in electrical appliance industry in the Chinese market. In the supply chain management, the bullwhip effect is a phenomenon can never be ignored. The bullwhip effect has being defined as information distortion when orders move form downstream enterprises to the supplier (Lee et al 1997b). The distortion information was amplified step by step, and finally propagates to the enterprise marketing, logistics, manufacture and other fields. The existence of the bullwhip effect weakens the ability to add value and competitiveness of the supply chain. Hence, enterprises must collaborate and jointly mitigate the bullwhip effect to reach groups coexist. This work focus on the electrical appliance industry in China, and based on the successful experience of the case company, Haier Group, to formulate recommendations. Firstly, this research analysis the four causes of the bullwhip effect: demand forecast, price fluctuations, order quantity and short game (Lee et al 1997a). After analyze these causes, this study begins to identify the impacts which the bullwhip effect bring to the members of supply chains. The most obvious impacts can be defined as inaccurate forecasting, inadequate customer service and high inventory cost. Next, the paper evaluate the measures of Haier implement to dampen the bullwhip effect. Information sharing, the key point to solve the problem has been use in Haier. In addition to this, the Just in Time (JIT) strategy which include JIT purchase, JIT delivery and JIT distribution is another important measure for Haier to achieve the goal of mitigate the bullwhip effect. Overall Every Control and Clear (OEC) management was created by Haier Group and aims to improve the supply chain management, is another countermeasure to deal with the bullwhip effect. Besides, the inventory management also have an important role in gaining the control of bullwhip effect. In summary, the successful experience on dampening the bullwhip effect of Haier can shine a light for electrical appliance industry in China on solving the similar problem. Information sharing is always the key point to mitigate the bullwhip effect, and related instructions should build to remove the barriers of sharing information.
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Andrade, Alexandre Maçada. "Bullwhip effect e capacidade absortiva das empresas : uma pesquisa com múltiplos casos." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2009. http://hdl.handle.net/10183/18438.
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O funcionamento da cadeia de suprimentos é um tema atual que tem motivado muitas pesquisas para o entendimento da sua dinâmica como fonte de obtenção de vantagem competitiva. O bullwhip effect - efeito de oscilação de demanda dentro da cadeia de suprimentos - é um dos causadores de ineficiências operacionais e de consequentes gastos desnecessários. Esse fenômeno ainda não foi estudado em sua totalidade; a maioria das pesquisas até então utilizaram-se de análises quantitativas, não levando em conta fatores qualitativos presentes em situações de oscilação de demanda, tais como: a experiência do programador de demanda, as capabilidades desenvolvidas pela empresa e os métodos que ela utiliza para integrar o conhecimento sobre o fenômeno. Esta pesquisa contribui nesse sentido. Coloca em evidência, por meio da análise qualitativa do bullwhip effect e dos fundamentos do processo de capacidade absortiva. Busca-se integrar esses dois conceitos, até então não abordados conjuntamente. A reunião desse referencial e dos resultados obtidos por intermédio das observações deverá fornecer subsídios para a melhor compreensão do fenômeno. A estratégia de pesquisa selecionada se deu por meio de estudos de caso com três empresas brasileiras, de diferentes setores. Entrevistaram-se sete executivos das empresas, responsáveis pela programação da produção e a análise de demanda. Foram encontrados muitos pontos convergentes entre a literatura e a prática empresarial, principalmente sobre os fundamentos da capacidade absortiva em uma situação de bullwhip effect, como também entre as diferentes dimensões da capacidade absortiva per se. A principal contribuição da pesquisa está em integrar orientações teóricas e ações práticas desenvolvidas pelas empresas sob o bullwhip effect, relacionadas com a capacidade absortiva, dando destaque aos fatores humanos, o que propicia um referencial mais abrangente para examinar esses processos. Em nível gerencial, oferece-se subsídios aos gestores no aprimoramento de técnicas de absorção do conhecimento em situações de oscilação de demanda, tornando suas previsões e a produção mais eficientes.The operation of the supply chain is a current topic and it has motivated many researches in order to understand its dynamic as source of obtaining competitive advantage. The bullwhip effect - the effect of oscillating demand inside the supply chain - is one of the originators of operational inefficiencies and consequent unnecessary expenditure. This phenomenon has not been studied in its totality yet; most researches have used quantitative analysis so far, not taking into account qualitative factors which are present in oscillating demand situations, such as: the experience of the demand manager, the capabilities developed by the company and the methods which it uses to integrate the knowledge about the phenomenon. This research contributes in this sense. It highlights through the bullwhip effect qualitative analysis and the process fundamentals of absorptive capacity. It pursuits to integrate these two concepts which have not thus far been approached together. The reunion of this reference and the obtained results through remarks should provide subsidies for better comprehension of the phenomenon. The research strategy selected was through case studies with three Brazilian companies of different sectors. Seven executives of the companies were interviewed; they are responsible for the production programming and for the demand analysis. Many convergent points were found between literature and the business practice, mainly concerning the fundamentals of absorptive capacity in a bullwhip effect situation, as well as among the different dimensions of absorptive capacity per se. The main contribution of the research is to integrate theoretical orientations and practical actions developed by the companies under the bullwhip effect, which are related to the absorptive capacity, highlighting to the human factors, which provides a reference more comprehensive to examine these processes. In a managerial level, subsidies are offered to the managers in the improvement of the absorption techniques of the knowledge in oscillating demand situations, making their forecasts and the production more efficient.
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Onuoha, Augustina Tina. "Strategies to Minimize the Bullwhip Effect in the Electronic Component Supply Chain." ScholarWorks, 2018. https://scholarworks.waldenu.edu/dissertations/6258.
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Supply chain leaders in the information technology industry face challenges regarding their ability to mitigate amplified demand and supply variability in a supply chain network--the bullwhip effect--and reduce adverse implications on their component supply chain networks. The purpose of this multiple case study was to explore the strategies supply chain leaders in the United States used to reduce the bullwhip effect. Bullwhip effect theory served as the conceptual framework. Participants in the study were 5 purposefully selected supply chain leaders in the state of Texas who successfully implemented strategies to reduce the bullwhip effect on their networks. Data were collected from semistructured interviews and analysis of documents from the participants' websites. The data were analyzed using the 5 data analysis steps consistent with Yin's approach: collection, stratification, reassembly, interpretation, and conclusion. Four themes emerged from data analysis: (a) collaboration strategy, (b) communication strategy, (c) component shortage reduction strategy, and (d) resource management strategy. Supply chain leaders might use the findings of this study to reduce the bullwhip effect within their networks and improve their profitability. The implications for positive social change include the potential for leaders to improve environmental sustainability by using effective supply chain strategies to reduce the accumulation of excess inventories, reduce transportation fuel usage, and lessen the consumption of natural resources.
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Lu, Jainping. "Minimising the bullwhip effect in efficient and responsive supply chains using genetic algorithms." Thesis, University of Ulster, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.507573.
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Strand, Mathias. "Service bullwhip effect inom kunskapsintensiv tjänsteverksamhet : En fallstudie på ett analys- och teknikkonsultföretag." Thesis, Uppsala universitet, Institutionen för teknikvetenskaper, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-329949.
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In this study, I have developed the theoretical concept Service Bullwhip Effect (SBWE) by examining it within the professional services context through a single case study at a Swedish consultancy firm. The research questions that have been guiding the study are the following: F1. How does the service bullwhip effect differ in professional service firms compared with other service firms? F2. How can the service bullwhip effect be mitigated within professional service firms? The purpose of the study is thus to contribute to the research area of Service Supply Chain Management, and its theoretical concept SBWE. I do this by studying the SBWE within the context of professional service firms (PSF), and analyze how it differentiate itself from other service firms, and how it can be mitigated within this context. The methodology used have been a combination of data sources that were collected in the form of primary qualitative data, and secondary quantitative data from the service supply chain of a consultancy firm. My findings indicate that a SBWE exists to some extent within the professional services context. Its presence, however, was limited due to the inherent characteristics of PSFs. From this I put forward the following three propositions: H1. The service bullwhip effect exists to some extent within professional service firms, and primarily in the form of a negative effect due to a work underdelegation. H2. Shortage gaming does not exist within the professional services context due to the close relation these firms have with its customers. H3. Batch ordering exists within professional service firms in the form of project clusters. Furthermore, managerial recommendations are also provided on how to mitigate the SBWE within the PSFs. My findings points towards a reduced emphasis on the individual utilization rate for the more senior consultants within the firm. Instead, I see that a larger emphasis should be put on the economic performance of projects when evaluating consultants that are project leaders. Research implications & limitations - As a single case, the research achieves a significant depth within the studied consultancy context, but have a limited generalizability. Therefore, the developed propositions will need to be tested within other types of PSFs, and thus with different sets of characteristics.I denna studie har jag byggt vidare på teorier kopplade till Service Bullwhip Effect (SBWE) genom att undersöka konceptet inom den kunskapsintensiva tjänstesektorn. Detta har jag gjort genom en fallstudie på analys- och teknikkonsultföretaget WSP i form av en kvalitativ och kvantitativ datainsamling. Den insamlade empirin jämfördes med resultat från tidigare studier för att analysera huruvida SBWE existerar inom kunskapsintensiva tjänsteverksamheter, och hur denna effekt i så fall skiljer sig från andra tjänsteverksamheter. Utifrån analysen har jag fört en diskussion med koppling till de forskningsfrågor som styrt studien: F1. Hur skiljer sig Service Bullwhip Effect inom kunskapsintensiv tjänsteverksamhet jämfört med andra tjänsteverksamheter? F2. Hur kan Service Bullwhip Effect hanteras inom en kunskapsintensiv tjänsteverksamhet? Studiens slutsatser utifrån den första forskningsfrågan (F1) pekar bland annat på att en SBWE existerar till viss del inom kunskapsintensiva tjänsteföretag. Dock inte i samma utsträckning som inom icke kunskapsintensiva tjänsteverksamheter. Dessa slutsatser summeras i form av tre nya hypoteser: H1. The Service Bullwhip Effect existerar till viss del inom kunskapsintensiv tjänsteverksamhet, och främst i form av en negativ effekt på grund av en underdelegation av arbetsuppgifter. H2. Shortage Gaming existerar inte inom kunskapsintensiv tjänsteverksamhet på grund av den nära relationen med kunderna. H3. Batch ordering existerar inom kunskapsintensiv tjänsteverksamhet i form av uppdragskluster. De dragna slutsatserna konfirmerar därmed teorierna inom området samtidigt som branschspecifika adapteringar av teorin föreslås utifrån de särskilda förhållandena som råder inom den kunskapsintensiva tjänstesektorn. Dessa slutsatser har dock en låg generaliserbarhet och validitet då jag i denna studie undersökt ett specifikt fall, och därmed presenterar jag mina slutsatser i form av hypoteser som kräver testning genom ytterligare studier. Slutligen ger jag ledningsmässiga rekommendationer utifrån den andra forskningsfrågan (F2). Dessa rekommendationer har sitt fokus på hur SBWE kan motverkas utifrån det specifika fallet inom konsultföretaget, och hur en rådande underdelegation kan bearbetas av verksamhetens ledning. För att motverka SBWE, och en underdelegation av arbetsuppgifter, så rekommenderar jag bland annat att seniorkonsulterna utvärderas med en låg prioritet utifrån deras beläggningsgradskrav, och med hög prioritet utifrån deras ansvar över uppdragsekonomin.
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Yuan, Xin. "A model to mitigate the bullwhip effect by ordering policies and forecasting methods." Thesis, University of Ottawa (Canada), 2006. http://hdl.handle.net/10393/27431.
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This thesis considers an important phenomenon: the bullwhip effect - the amplification of variability of demand as one moves up a supply chain. We apply Agent-Based Modeling (ABM) at the macro level of our system to build relationships among the trading partners; and then we utilize system dynamics to model rules like ordering policy or inventory management at the micro level. We define these rules according to Sterman's generic stock acquisition and ordering heuristic in his Beer Distribution Game Model (Sterman 1989, 321-339). By including additional forecasting methods like moving average, Holts, and double exponential smoothing (DES) method, we extend the model to investigate how different ordering policies and forecasting methods affect the bullwhip effect. Through simulations in the ordering policy space, we demonstrate that fed with a local trend customer order pattern, the bullwhip effect can be mitigated significantly if the suitable forecasting method like Holts or DES is applied under the right ordering policy that has a slow adjustment to the discrepancy of the stock. Comparing with previous research, we extend Sterman's model to investigate what other managerial behaviours, like the aggregation effect, the varied ordering policy and additional forecasting methods would bring to the bullwhip effect. In the "smoothing" method, we extend the moving average and exponential average, which appeared in Forrester's study (Forrester 1961), to Holts and DES method. In modeling, we differ from CDRS (Chen, Drezener, Ryan, and Simchi-Levi 2000, 436-443) and CRS (Chen, Ryan, and Simchi-Levi 2000, 269-286) and Yao (2001) by replacing order-up-to policy with the heuristic ordering policy. Our research has another important managerial insight: through the right ordering policy and forecasting method, trading partners can alleviate the bullwhip effect without adopting information sharing, which may lead to other problems, like mutual trust or additional cost.
Key words. Supply chain management; Bullwhip Effect; System dynamics; Agent-Based Modeling; Forecasting.
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Smith, Emily (Emily C. ). "Reducing the demand forecast error due to the bullwhip effect in the computer processor industry." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/59176.
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Thesis (M.B.A.)--Massachusetts Institute of Technology, Sloan School of Management; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering; in conjunction with the Leaders for Global Operations Program at MIT, 2010.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 70-71).
Intel's current demand-forecasting processes rely on customers' demand forecasts. Customers do not revise demand forecasts as demand decreases until the last minute. Intel's current demand models provide little guidance for judging customer orders when the market changes. As a result, during the economic downturn of Q3 and Q4 '08, Intel's model could not predict how much billings would decrease. The demand forecast had large amounts of error caused by the bullwhip effect (order amplification in a supply chain). This project creates a new demand forecast model in two phases. The first phase investigated the supply chain of OEMs and Retailers. The second phase of the project used the supply chain information discovered in phase one to create a new demand forecast that reduces the error caused by the bullwhip effect. The first phase determined that the average time it takes a CPU to go from Intel to end customer purchase is seventeen weeks. The first phase also indentified ownership of products throughout the supply chain and parties making purchase decisions. The supply chain information was then used in the second phase of the project to create a demand forecast model. The new model is a heuristic model that simulates quarterly purchase decisions of retailers and OEMs including lead times and inventory. The resulting model allows Intel to monitor and react to consumption changes faster than waiting for customers to change their demand forecasts. The model also provides a better forecast during times of change. The model reduces the error due to the bullwhip effect and indentifies early when a downturn or upturn is going to happen in ordering behavior.
by Emily Smith.
S.M.
M.B.A.
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Reddy, Kothi Abhilash. "The impact of replenishment parameters and information sharing on bullwhip effect for short life cycle products." To access this resource online via ProQuest Dissertations and Theses @ UTEP, 2007. http://0-proquest.umi.com.lib.utep.edu/login?COPT=REJTPTU0YmImSU5UPTAmVkVSPTI=&clientId=2515.
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Hussain, Matloub. "Extended understanding of the causes and control of the bullwhip effect in multi-echelon supply chains." Thesis, University of Liverpool, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.507173.
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Lindmark, Eric, and Svenningsson Jakob. "Optimization of inbound value flow in a manufacturing company : A case study on the bullwhip effect." Thesis, Tekniska Högskolan, Högskolan i Jönköping, JTH, Logistik och verksamhetsledning, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-46793.
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Purpose – The purpose of the research is to explore how to reduce waste in value flows and to minimize the bullwhip effect within operations. To fulfill and answer the purpose of the research three questions of issue has been established: 1. What issues in value flows can be identified, regarding inbound and outbound flows? 2. How can issues in value flows be minimized, with regards to inbound and outbound flows? 3. How can a model be created to understand the relationship between value flow improvements and the bullwhip effect? Method – To retrieve understanding of the topic that thesis involves, support of literature studies, observations and data collection was used. The literature study created a foundation of theoretical framework. The data collected from the case company formed a base that partly facilitates the purpose of this thesis. The theoretical framework and data collection were thoroughly analyzed and discussed in order to propose solutions for improvements. Findings – The research establishes different issues that can be identified in outbound and inbound flows such as; waste in transportation, waste in inventory, waste in movement and waste in overproduction. Further, in order to minimize the identified issues in inbound and outbound flows it is imperative to find out the root cause for the issues. When the root cause was established, statistical approach was utilized to further explain the issue. The findings from the statistical approach elucidated a large variance between supply and demand, resulting in a bullwhip effect. In order to minimize the bullwhip effect, improvements should focus on insufficiencies such as; lack of communication, order batching and disorganization. In addition, standardization through 5s approach mitigates the waste in transportation and movement. To understand the relationship between value flow improvements and the bullwhip effect, a causal loop diagram was created to understand the phenomenon from a system perspective. Implications – The research contributes with solutions on how to identify the bullwhip effect as well as highlighting the issues in value flows. Furthermore, this research solidifies the importance of using lean process to improve overall productivity in value flows. Limitations – The research was limited to one case company and one area in the case company. The answers that are presented in this research could increase the reliability and credibility if the authors had been able to investigate several areas at the case company or several companies. Furthermore, the date that has been retrieved is based solely on one supplier at the case company. Keywords – ‘Lean Process’, ‘Bullwhip Effect’, ‘Supply Chain Management’, ‘Continuous Improvement’, ‘System Perspective’ and ‘Statistical Analysis’.
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Adnan, Ziaul Haq. "Bullwhip Effect in Pricing in Varying Supply Chain Structures and Contracts Using a Game Theoretical Framework." Thesis, The University of North Carolina at Charlotte, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10269505.
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Bullwhip effect in Pricing (BP) refers to the amplified variability of prices in a supply chain. When the amplification takes place from the upstream (i.e. supplier’s side) towards the downstream (i.e. retail side) of a supply chain, this is referred as the Reverse Bullwhip effect in Pricing (RBP). On the other hand, if an absorption in price variability takes place from the upstream towards the downstream of a supply chain, we refer this phenomenon as the Forward Bullwhip effect in Pricing (FBP).
In this research, we analyze the occurrence of BP in the case of different game structures and supply chain contracts. We consider three game scenarios (e.g. simultaneous, wholesale-leading, and retail-leading) and two supply chain contracts (e.g. buyback and revenue-sharing). We analyze the occurrence of BP for some common demand functions (e.g. log-concave, linear, isoelastic, negative exponential, logarithmic, logit etc.). We consider some common pricing practices such as a fixed-dollar and fixed-percentage markup pricing and the optimal pricing game.
We discuss the conditions for the occurrence of BP based on the concavity coefficient and the cost-pass-through. We analyze the price variation analytically and then illustrate the results through numerical simulations. We extend the cost-pass-through analysis for a N-stage supply chain and conjecture the BP ratios for a N-stage supply chain. We compute cost-pass-through under both a buyback and a revenue-sharing contract. We compared the BP ratios between a revenue-sharing contract and a no-contract cases. We include both the deterministic and stochastic demand functions with an additive and a multiplicative uncertainty.
The results indicate that the occurrence of BP depends on the concavity coefficient of the demand functions. For example: RBP occurs for an isoelastic demand, FBP occurs for a linear demand, No BP occurs for a negative exponential demand etc. This study also shows that, FBP and RBP occur in varying magnitude for different types of games and supply chain contracts. The comparison between the stochastic model and the risk-less model shows that the additive or multiplicative uncertainty changes the price fluctuation. The comparison between contract and no-contract cases shows that the contract minimizes FBP or RBP in some cases.
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Lehnbom, Mia, and Patrik Holmberg. "Effekten av demand-supply chain management : Fallstudie från trävaruindustrin." Thesis, Högskolan i Gävle, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-19832.
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Enligt Carlsson och Rönnqvist (2005) och Frayret et al. (2007) blir det allt viktigare att arbeta med supply chain management inom trävaruindustrin. En utmaning är att finna ett arbetssätt för att hantera variationen i kundens efterfrågan. Idag hanteras variationen oftast genom onödigt stor lagerhållning (Lee et al., 1997b; So och Zheng, 2003). Syftet med studien är att utreda påverkande faktorer som bidrar till en varierande efterfrågan inom trävaruindustrin samt föreslå hur uppkomsten av dessa kan undvikas. För att svara på syftet har tre frågeställningar tagits fram och en fallstudie genomfördes på ett hyvleri. Informationsinsamlingen har skett genom intervjuer av anställda från olika avdelningar samt litteraturstudier. Studien visar att det finns flera utmaningar när det är stor variation på efterfrågan såsom brist på tillgång till prognoser och kommunikationsbrist med kunder. Det medför att planeringen av råvaruåtgången försvåras och det leder till svårigheter att uppnå leveransprecision. Slutsatsen visar att de påverkande faktorer som bidrar till en varierad efterfrågan är prisvariationer, orderstorlek och orderfrekvens. Prisvariationer kan undvikas genom ABC-indelning av produkterna utifrån produktefterfrågan. Prognoser underlättar uppskattning av efterfrågan men för ett fungerande prognosarbete krävs samsyn, nära relation samt god kommunikation mellan kund och leverantör. Problem med orderstorlek och orderfrekvens kan reduceras om kunden får avgöra orderstorleken utan att specifika krav måste uppfyllas. Slutsatsen visar även att faktorer såsom väderlek, trender, mode, helgdagar och rotavdragets eventuella försvinnande påverkar variationen i efterfrågan.According to Carlsson & Rönnqvist (2005) and Frayret et al. (2007) supply chain management in the wood products industry is getting more important. One of the challenges is to find a way to deal with customer’s fluctuating demand. Traditional solution to handle fluctuating demand is large inventory (Lee et al., 1997b; So & Zheng, 2003), which causes often high inventory cost for effective supply chain management. The aim of the study is to investigate factors that affect a fluctuating demand in the wood products industry and suggest how to reduce the fluctuating demand through related factors analysis in order to improve Demand-Supply chain management efficiency. For this pursose, a case study on a planing is conducted. To collect data, interviews with employees from different departments have been made along with literature studies. The study presents that there are many challenges for the fluctuation demand such as lack of forecasts and lack of communication with customers. This, in turn, will cause problems with planning of the raw material as well as difficulties to deliver the goods on time. The conclusion shows that the factors affecting a fluctuating demand are price variations, the orders batch size and order frequency. Price variations can be improved by ABC classification of the products by product demand. Forecasts will make the estimation of demand easier, although, in order to use forecasts properly a joint vision, close relationships and good communication with customer and supplier is required. Problems regarding batch size and order frequency can be reduced if the customer is allowed to decide the batch size with no specific requirements. The study also shows that factors such as weather, trends, fashion, holidays and disappearance of ROT work affects the fluctuating demand.
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Dias, George Paulus Pereira. "Gestão dos estoques numa cadeia de distribuição com sistema de reposição automática e ambiente colaborativo." Universidade de São Paulo, 2003. http://www.teses.usp.br/teses/disponiveis/3/3136/tde-08062004-180407/.
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O foco dessa dissertação está na gestão de estoques em sistemas multicamadas. O modelo de simulação construído considera o desempenho histórico de uma cadeia de distribuição de medicamentos versus a política de gestão proposta. Os objetivos principais do trabalho são: a avaliação quantitativa da política de cálculo de necessidades aplicada na gestão de sistemas multicamadas, a verificação da importância da cooperação entre os elos da cadeia de distribuição para gestão do fluxo de materiais e o estudo das curvas que representam o dilema nível de serviço versus custo total da cadeia. O modelo considera o fluxo de materiais a partir do estoque em processo do laboratório até a venda para as farmácias, que pode ser aproximada pela demanda dos medicamentos visto que os estoques das farmácias são relativamente pequenos e constantes ao longo do tempo. A modelagem de custos leva em conta o custo de estoque do laboratório e dos distribuidores, o custo de pedido dos distribuidores, o custo de transporte, o custo de entrega com atraso do laboratório e o custo de venda perdida dos distribuidores. Especificamente, são considerados cenários com e sem o compartilhamento de informações entre as empresas da cadeia. Consideram-se também cenários com e sem sazonalidade na demanda. Inicialmente, cada cenário simulado é preparado com a definição do período transitório da simulação, horizonte de simulação e número de réplicas necessárias. Depois disso, é feito o delineamento de experimentos para identificar quais variáveis de decisão têm efeito significativo sobre o custo total da cadeia. Finalmente, é feita uma busca da parametrização de cada um dos cenários que apresente o melhor custo total da cadeia. Os resultados da simulação mostraram que as práticas atualmente empregadas na gestão dos estoques das empresas podem ter seu desempenho melhorado com a utilização da política simulada na pesquisa. Os cenários nos quais se considerou o compartilhamento de informações tiveram desempenhos semelhantes aos sem esse compartilhamento. Dessa forma, para a política simulada, conclui-se que o valor do compartilhamento de informações foi relativamente pequeno. Nas simulações pode-se verificar a melhoria simultânea do nível de serviço e do nível de estoques da cadeia. Isso mostra que a política simulada mudou o dilema (trade-off) que interliga antagonicamente essas duas características de desempenho do sistema.This dissertation focuses on the inventory management for multi-echelon systems. The simulation model proposes a new inventory management policy and compares it to the historical performance of a medicine supply chain. The main objectives of this research are: the quantitative analysis of the method used for the calculation of material requirements in multi-echelon systems; the verification of the importance of the cooperation between the components of the supply chain to the material flow management; and the analysis of the curves which represent the trade-off between service level and total cost. The model takes into account the material flow from the laboratorys work in process up to the sales to the drugstores, which can be approximated by the demand of the final consumer, since the inventory kept by drugstores is relatively small and constant in time. The costs are calculated considering: the laboratorys and distributors inventory costs, the cost of orders from the distributors, the transportation cost, the laboratorys cost of late delivery and the distributors cost of lost sales. Scenarios with and without the sharing of information between the components of the supply chain were both considered. The same is true for scenarios with and without seasonality in the demand. Initially, each scenario was prepared with the definition of the warm-up period, the simulation horizon and the amount of required replications. Secondly, the design of experiments (DOE) was done in order to determine which decision variables have influence on the supply chain total cost. Finally, each scenario was tested with many different parameters in order to find the lowest cost for the supply chain. The simulation results have showed that the procedures currently applied for the inventory management can have their performance improved by the use of the policy proposed in this research. The results for the scenarios with the sharing of information were similar to the ones for the scenarios without the sharing. For that reason, we can conclude that, for the proposed inventory management policy, the value of the sharing of information through the supply chain was relatively small. In the simulations, both the service level and the total cost have improved. In this manner, it can be said that the new policy has improved this trade-off.
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Caldas, Pedro Tainha Saramago Mendes. "Impacto implementação E-kanban numa supply chain hospitalar." Master's thesis, Instituto Superior de Economia e Gestão, 2013. http://hdl.handle.net/10400.5/11176.
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Mestrado em Gestão e Estratégia IndustrialEste trabalho surgiu no sentido de tentar procurar uma possível solução para uma problemática, ao nível da suspeita de excesso de recursos envolvidos na operação logística, nomeadamente desperdício e, por outro lado, o fluxo de informação era descontínuo entre Logística e Serviços Clínicos. Culturalmente, as entidades prestadoras de saúde exigem ter elevados níveis de stock, de forma a tentar prestar o melhor Serviço ao paciente, pelo que se suspeita que requisitem material em excesso e em elevada variedade, originando um fluxo descontínuo de materiais, o que associado a um fluxo insuficiente de informação, poderá gerar uma afectação de recursos demasiado elevado.. O outro objectivo igualmente relevante passa por melhorar o processo de Gestão Logística, pretendendo-se alcançar também uma redução de custos, redução de stock médio no armazém central, aumentar a disponibilidade de stocks e, por conseguinte, o nível de serviço prestado aos clientes internos conseguindo um maior grau de satisfação. Mais concretamente, foi escolhida a ferramenta E-Kanban. Nesta metodologia os pedidos de materiais de consumo clínico são gerados automaticamente, quando o stock fica abaixo do ponto de pedido criando uma dinâmica contínua entre Logística e Serviços.
The objective of this research is to find a possible solution related with a suspicion of excess resources involved on the logistics operations, such as waste and poor information flow, between Logistics and Clinical Services (internal customers). Historically Medical Services requires high stock levels in order to provide the best Customer Service, which could make that they order excessive materials and high variability, doing a discontinuous product flow and insufficient information, creating a high resources allocation. Thus the main objective of TFM is introducing Lean Thinking at IPOLFG and test if a tool Lean implementation could be beneficial to reduce the constraints identified above and the results and objectives of the hospital. At the Logistics Management, the goal is to achieve a cost reduction, as well as, a reduction in average stock at the central warehouse, improving the availability of stocks with the proposal to get a high customer service satisfaction. Specifically the select tool was the E-Kanban. In this methodology there is no more physical requests, except in emergencies, since the EDI system place automatically requests when the stocks is below the reorder point.
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Pan, Youqin. "Impact of Forecasting Method Selection and Information Sharing on Supply Chain Performance." Thesis, University of North Texas, 2009. https://digital.library.unt.edu/ark:/67531/metadc12176/.
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Effective supply chain management gains much attention from industry and academia because it helps firms across a supply chain to reduce cost and improve customer service level efficiently. Focusing on one of the key challenges of the supply chains, namely, demand uncertainty, this dissertation extends the work of Zhao, Xie, and Leung so as to examine the effects of forecasting method selection coupled with information sharing on supply chain performance in a dynamic business environment. The results of this study showed that under various scenarios, advanced forecasting methods such as neural network and GARCH models play a more significant role when capacity tightness increases and is more important to the retailers than to the supplier under certain circumstances in terms of supply chain costs. Thus, advanced forecasting models should be promoted in supply chain management. However, this study also demonstrated that forecasting methods not capable of modeling features of certain demand patterns significantly impact a supply chain's performance. That is, a forecasting method misspecified for characteristics of the demand pattern usually results in higher supply chain costs. Thus, in practice, supply chain managers should be cognizant of the cost impact of selecting commonly used traditional forecasting methods, such as moving average and exponential smoothing, in conjunction with various operational and environmental factors, to keep supply chain cost under control. This study demonstrated that when capacity tightness is high for the supplier, information sharing plays a more important role in effective supply chain management. In addition, this study also showed that retailers benefit directly from information sharing when advanced forecasting methods are employed under certain conditions.
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Pereira, Pedro Gomes Torres. "O Bullwhip Effect no controlo da produção em obra. Uma abordagem de utilização com base na análise comparativa entre controlo tradicional e o Last Planner System." Master's thesis, Faculdade de Ciências e Tecnologia, 2013. http://hdl.handle.net/10362/9931.
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Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para obtenção do Grau Mestre em Engenharia Civil – Perfil de ConstruçãoA implementação do Last Planner System (LPS) tem produzido bons resultados na redução do tempo útil dos empreendimentos de construção, no incremento de produtividade e na mitigação da variabilidade inerente à gestão da construção. Apesar disso, verifica-se que os níveis de Percent Plan Complete (PPC) atingidos com a implementação deste sistema não atingem o valor médio idealizado de 100%. Desta forma, é sugerido que existe espaço para melhorar o processo de ges-tão do LPS, dado que a estrutura conversacional deste sistema gera padrões de variabilidade, ine-rente ao processo de planeamento e gestão, que se pode amplificar ao longo da cadeia hierárquica do LPS. Este fenómeno de amplificação da variabilidade tem o nome de Bullwhip Effect (BWE). O trabalho apresentado parte da premissa de que o BWE existe tanto no controlo de produção com recurso ao LPS como no controlo de produção tradicional, dado que este último não dispõe dos métodos do LPS para redução da variabilidade. É estudada uma metodologia de detecção e quantificação do BWE e apresentado um método que permite a obtenção de uma base de compa-ração entre o LPS e o controlo de produção tradicional, para uma posterior análise comparativa entre os dois métodos de controlo. A análise efectuada baseia-se em dois casos de estudo, o pri-meiro localizado no Perú e desenvolvido com LPS, e o segundo levado a cabo em Portugal com utilização de controlo tradicional. Após a análise dos casos de estudo, propõe-se a utilização do índice de BWE como ferramenta de monitorização e controlo da variabilidade em obra. Propõe-se ainda a utilização deste indicador como um Key Performance Indicator (KPI), que permita aos intervenientes na gestão um controlo mais aprofundado da variabilidade inerente à produção industrial, em particular na construção.
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Bernatonis, Donatas. "Neapibrėžtumo efekto tiekimo grandinėse mažinimo modeliavimas." Master's thesis, Lithuanian Academic Libraries Network (LABT), 2005. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2005~D_20050810_191122-74541.
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In this work bullwhip effect in the supply chains was studied and reduction of the effect was analyzed. Simulation was done with Rockwell Arena software. Eight different models were created using two different bullwhip reduction schemes (batching removal and information sharing) with two different ordering distributions (normal and exponential distribution). Analyzed supply chain consisted of two groups of customers, two distributors, one manufacturer and two suppliers, producing different components for manufacturer. Information processing, lead and manufacturing times where stochastic values. Analysis is based on the mean value and standard deviation of orders and inventory level. Research showed, that most effective bullwhip reduction scheme is information sharing which let to reduce supplier’s inventory level up to 90%. Also effect reduction schemes are more effective when order variability is greater. This work is primary supply chain model. Therefore author offers to continue this work and do next analysis: to analyze other order distributions’ and other stochastic model variables influence to bullwhip reduction schemes, to analyze other supply chain structures, to do mathematical evaluation.
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García, Salcedo Carlos Andrés. "Inventory Control in Supply Chains: An Internal Model Control Approach." Doctoral thesis, Universitat Autònoma de Barcelona, 2013. http://hdl.handle.net/10803/116201.
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Esta tesis se basa en el diseño de estrategias de gestión de inventario en cadenas de suministro usando la teoría de control. El principal objetivo es proponer un esquema de control para resolver los principales problemas que aparecen en el controla gestión de inventario de una cadena de suministro (incertidumbre en el retardo, el efecto látigo y el déficit de inventario). Este objetivo principal se divide en dos objetivos:
1. La neutralización de los efectos causados por el retardo de entrega de un pedido.
2. Diseño de políticas de inventario que permitan un balance entre el rechazo a la perturbación (demanda) y el seguimiento del inventario objetivo.
Dado que el esquema de control por modelo interno (IMC) permite tratar los objetivos (1) y (2) bajo el mismo paradigma de control, pero de una manera disociada, éste se presenta en esta tesis como una nueva política de reposición de inventario en cadenas de suministro. Sin embargo, el IMC requiere el conocimiento del retardo para compensar sus efectos. Esta situación no es viable cuando el retardo cambia durante el proceso, situación común en las cadenas de suministro. Por lo tanto, la investigación empieza con la identificación del retardo. Así, en esta tesis se formula un algoritmo de identificación que permite estimar el verdadero valor de los retardos de la cadena de suministro. Estos valores se utilizan para adaptar el bloque de retardos en el esquema de control. De ese modo, el objetivo (1) se finaliza.
El objetivo (2) se basa en el diseño de los controladores del esquema IMC. El objetivo de los controladores de IMC es mantener los niveles de inventario de la cadena de suministro cerca del inventario objetivo mitigando el efecto látigo. Cada entidad de la cadena de suministro puede operar en varios modos de trabajo durante el tiempo: suministro infinito y suficiente existencia, (SISE), suministro infinito y Bajas existencia, (SIBE), Suministro limitado, (SL). Cuando el tiempo de espera es demasiado largo y existe incertidumbre en la demanda, muchas empresas optan por utilizar una estrategia de inventario de seguridad para garantizar la satisfacción de la demanda del cliente. En virtud de esta estrategia de la cadena de suministro está siempre en el modo de trabajo (SISE). Cuando el inventario es insuficiente, la cadena de suministro puede trabajar en cualquiera de los modos de trabajo (SISE), (SIBE) o (SL).
Por lo tanto, comenzamos proponiendo el diseño del sistema de control para una cadena de suministro bajo la estrategia de inventario de seguridad (SISE). El diseño está basado en las directrices del esquema IMC en el cual se realiza un balance entre la mitigación del efecto látigo y el seguimiento del inventario.
Después de eso, el sistema de control se diseña para una cadena de suministro trabajando sin inventario de seguridad (es decir, en cualquier modo de funcionamiento (SISE), (SIBE) o (SL)). Por lo tanto, se propone un sistema de control de inventario conmutado bajo la estrategia de control descentralizado. Este consiste en un banco de controladores diseñados para cada posible caso de funcionamiento de cada entidad y una lógica de conmutación que selecciona el mejor controlador en cada instante de tiempo. Así, el objetivo (2) está terminado.This thesis relies on the design of inventory management strategies in supply chain systems by using control theory approaches. The main objective is to propose a control scheme to solve the principal problems appearing in the inventory control of the supply chain (uncertainty in the lead time, the bullwhip effect and the inventory drift). This objective is divided in two particular objectives: 1. On the one hand, the counteraction of effects caused by the existing delay between the time at which an order is placed on the immediate supplier and the moment at which the petition is satisfied. 2. On the other hand, the design of inventory policies allowing a trade-off between the disturbance (demand) rejection and the inventory target tracking. Since the internal model control scheme (IMC) allows to tackle the objectives (1) and (2) under the same paradigm of control but in a decoupled way, the IMC scheme is presented in this thesis as a novel inventory replenishment policy for the entire supply chain. Nevertheless, the IMC requires the perfect knowledge of the lead time to compensate its effects. This situation is not viable when the delay changes during the process which is a common situation in supply chains. Hence, first of all, the research is focused on the identification of the lead time. As a result of this part of the research, an identification algorithm that allows to estimate the actual delay values of the entire supply chain at each time interval is formulated. The estimated delay values are used to adapt the delay block in the control scheme. Thereby, the particular objective (1) is finalised. The objective (2) relies on the design of the IMC scheme controllers. The aim of the IMC controllers is to keep the inventory levels of the supply chain close to the inventory target mitigating the bullwhip effect. Each echelon of the supply chain may operate under several working modes during the time: Infinite Supply and High stock, (ISHS), Infinite Supply and Low Stock, (ISLS), Limited Supply, (LS). When the lead time is too long and there exist uncertainty in the demand level, many companies choose to use a safety stock strategy to assure the customer demand satisfaction. Under this strategy the supply chain is always in the (ISHS) working mode. When the stock is insufficient, the supply chain may work under any of (ISHS), (ISLS) or (LS) working modes. Therefore, we start proposing the design of the control scheme for supply chain under safety stock strategy (ISHS). The design is based on the IMC guidelines where a trade-off between the bullwhip effect avoidance and inventory tracking is carried out, which is the second objective of the research. After that, the control scheme is designed for a supply chain working without safety stock (i.e. under any working mode (ISHS), (ISLS) or (LS)). Therefore, we propose a switched inventory control system for a serial multivariable supply chain under decentralized control strategy. This consists in a bank of controllers designed for each possible operation case of each echelon and a switching logic that selects the best controller at each instant time. Thus, the objective (2) is finalised.
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Fioriolli, Jose Carlos. "Modelagem matemática do efeito chicote em cadeias de abastecimento." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2007. http://hdl.handle.net/10183/10357.
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O aumento da variabilidade da demanda ao longo de uma cadeia de abastecimento é conhecido como Efeito Chicote (EC). A modelagem deste fenômeno é fundamental para a quantificação de sua intensidade, ajudando a reduzir seus impactos negativos sobre o nível de serviço e sobre os estoques em uma cadeia de abastecimento. Esta tese apresenta uma proposta de modelagem do EC que tem por objetivo aumentar a precisão na quantificação deste fenômeno em ambientes com demanda e lead time estocásticos. O novo modelo considera dois elementos que não estão presentes nos principais modelos disponíveis na literatura: a variabilidade no lead time de entrega de pedidos e a incorporação de um ajuste para contemplar uma política adequada de tratamento dos excessos de estoque. Além disso, define de modo mais preciso o papel do coeficiente de variação da demanda na quantificação do EC. A utilização do modelo proposto aumenta a eficiência da gestão de cadeias de abastecimento ao contribuir para atenuar a propagação do EC, elevar o nível de serviço e reduzir os níveis local e global dos estoques. Neste documento, os principais modelos de quantificação do EC são apresentados e analisados, com destaque para os trabalhos de Lee et al. (1997b), Chen et al. (2000), Fransoo e Wouters (2000) e Warburton (2004); nessa análise foram identificadas várias deficiências, capazes de produzir fortes distorções no processo de quantificação do EC. O modelo proposto supre integralmente estas deficiências e apresenta elementos que indicam que a intensidade e o comportamento estocástico e serial do EC só podem ser adequadamente modelados se a variabilidade do lead time for considerada e se os excessos de estoque forem utilizados no cálculo do tamanho dos pedidos. O novo modelo, além de contribuir para o entendimento da dinâmica do EC e para a ampliação do respectivo campo de discussão, representa adequadamente a complexidade das relações entre as variáveis associadas ao EC, o que lhe confere alta capacidade preditiva. Complementarmente, demonstra-se que o modelo de Chen et al. (2000) constitui um caso particular do modelo proposto.The increase in demand variability as information flows from customers to manufacturers in a supply chain is known as the Bullwhip Effect (BE). Modeling this phenomenon is fundamental in measuring its intensity, aiming at reducing its negative impacts on both service and inventory levels in the supply chain. In this dissertation we propose a new, more precise mathematical model for quantifying the BE in systems with stochastic demand and lead time. The new model takes into account the lead time variability and is adjusted to a more realistic treatment of negative order quantities that may arise in some inventory cycles, two elements not present in the main available models in the literature. In addition, the model enables a more precise assessment of the role that the demand coefficient of variation plays in the quantification of the BE. The use of the proposed model enables an improved management of the supply chain by attenuating the propagation of the BE, increasing the service level and reducing inventory levels both locally and globally. In this dissertation, the main models for quantifying the BE are presented and analyzed, with emphasis in the works of Lee et al. (1997b), Chen et al. (2000), Fransoo and Wouters (2000) and Warburton (2004); in that analysis were identified several deficiencies, able to generate severe distortions in the quantification of the BE. The proposed model fully overcomes these deficiencies and presents elements that indicate that the intensity and stochastical and serial behavior of the BE can only be appropriately modeled if the lead time variability is considered and if inventory excesses are used in the order size calculation. The new model, in addition to contribute to the understanding of the BE dynamics enriching its analysis, represents appropriately the complexity of relationships among variables associated with the BE, contributing to its high predictive capacity. Finally, it is demonstrated that the model in Chen et al. (2000) represents a special case of the proposed model.
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Frykfors, Alexis, and Philip Strand. "Sambandet mellan säkerhetskrav och höga lagernivåer inom läkemedelsbranschen : En fallstudie på Fresenius Kabi." Thesis, Högskolan i Gävle, Industriell ekonomi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-24367.
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Background: An organization's ability to control bound material can be the difference between success or failure. Organizations that effectively work with supply chain management has strengthened their positions and increase their competitive edge on the global market. Organizations is the pharmaceutical industry has a major social responsibility by ensuring a continuous flow of medicines as well as pharmaceutical equipment. The industry is controlled by the strict regulations. The stringent security requirements for delivery reliability and delivery precision combined with extensive production regulations have resulted in these organizations having difficulty in maintaining even inventory levels. Purpose: The study aims to investigating the correlation between high level of safety requirements in the pharmaceutical industry and high inventory levels with the help of a case study. The study wants to investigate consequences of such connection as well investigate potential solution in which organizations can reduce their inventory levels without jeopardizing the delivery precision and delivery safety of pharmaceutical organizations. A case study has been conducted at the pharmaceutical company Fresenius Kabi who is a global market leader in the production of intravenous nutritional solutions. Finding: Findings of the study indicates that safety requirements controlling the pharmaceutical industry have a major impact on the organization's production planning and storage. The consequences of the high security requirements results in in uneven production patterns and tied capital in high inventory levels. The consequences also indicated on a Bullwhip-effect. Lean management enables organizations in the pharmaceutical industry to establish even production patterns and reduce their inventory levels. The study presents a new factor that prevents organizations in the pharmaceutical industry to reduce the number of articles. The new factor has a strong link to why organizations in the pharmaceutical industry have high inventory levels.Bakgrund: Hantering av lager och uppbundet material kan vara avgörande för en organisations framgång eller misslyckande. En ökad globalisering av dagens marknad har lett till att organisationer som effektivt arbetar med supply chain management stärker sina positioner och ökar sina konkurrensfördelar. En bransch på den globala marknaden som verkar under håra regleringar är läkemedelsbranschen. Branchen har ett stort samhällsansvar genom att säkerställa ett kontinuerligt flöde av läkemedel samt läkemedelsutrustning. De hårda säkerhetskraven på leveranssäkerhet och leveransprecision i kombination med omfattande produktionsregleringar har resulterat i att dessa organisationer har svårt att upprätthålla jämna lagernivåer. Syfte: Med hjälp av en fallstudie vill studien undersöka hur sambandet mellan höga säkerhetskrav och höga lagernivåer inom läkemedelsbranschen ser ut. Studien vill undersöka hur sambandet påverkar organisationer inom läkemedelsbranschen samt analysera hur man medhjälp av olika åtgärder kan minska lagernivåer utan att äventyra organisationernas leveransprecision och leveranssäkerhet. Fallstudien är baserad på läkemedelsorganisationen Fresenius Kabi. Fresenius Kabi är en global aktör som är marknadsledande inom produktion av intravenösa näringslösningar. Studien har undersökt produkten smofkabvien som produceras i Uppsala i syfte till att besvara studiens frågeställning. Med hjälp av intervjuer och insamlad sekundärdata besvaras studiens syfte. Slutsats: Studienkonstaterar att säkerhetskraven som reglerar läkemedelsbranschen har en stor inverkan på organisationens produktionsplanering och lagerhållning. Resultatet av de höga säkerhetskraven resulterar i ojämna beställning-och produktionsmönster vilket resulterar i hög kapitalbindning samt indikerar på en potentiell Bullwhip-effekt inom försörjningskedjan. Med hjälp av Lean management, heijunka och just-in-time kan organisationer inom läkemedelsbranschen upprätta jämna produktion-och beställningsmönster samt reducera sina lagernivåer. Studien presenterar en ny faktor vilken förhindrar organisationer inom läkemedelsbranschen möjlighet att reducera antalet artiklar. Den nya faktorn har en stark koppling till varför organisationer inom läkemedelsbranschen höga lagernivåer.
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Korotkevičius, Artūras. "Neapibrėžtumo efekto įtaka tiekimo grandinėms." Master's thesis, Lithuanian Academic Libraries Network (LABT), 2008. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2008~D_20080723_081414-63035.
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Baigiamajame magistro darbe nagrinėjama viena iš pagrindinių tiekimo grandinių valdymo problemų ─ neapibrėžtumo efektas, didinantis įmonių veiklos sąnaudas, sandėlio lygį ir mažinantis konkurencingumą. Pagrindinis baigiamojo darbo tikslas yra pateikti galimus neapibrėžtumo efekto mažinimo būdus tiekimo grandinėse. Darbe yra analizuojama neapibrėžtumo efekto samprata, įtaka tiekimo grandinėms, identifikavimo būdai, atsiradimo priežastys ir efektą mažinančių priemonių panaudojimo efektyvumas. Išnagrinėjus teorinius ir praktinius neapibrėžtumo efekto aspektus, pateikiamos baigiamojo darbo išvados ir siūlymai. Darbą sudaro 5 dalys: įvadas, analitinė-metodinė, eksperimentinė-tiriamoji dalis, išvados ir siūlymai, literatūros sąrašas. Darbo apimtis – 62 p., 23 iliustr., 4 lent., 34 bibliografiniai šaltiniai. Atskirai pridedami darbo priedai.The main topic of this thesis is bullwhip effect, under which influence negative factors such as increased warehouse level, demand variations, big internal expenditures and decreased competition can seriously affect efficiency of whole supply chain. The main goal of this thesis is suggest possible ways of bullwhip effect reduction in supply chain. In this is thesis author is analyzing: conceptions of bullwhip effect influence on supply chain, ways of effect identification; search for methods to decrease bullwhip effect. Main tolls of bullwhip effect reduction are: proper information sharing; reducing of shipment transportation time; using of efficient demand forecasting method; development of VMI system, and installation of up-to-date IT systems. Structure: introduction, analytical part, experiment, conclusions and suggestions, references. Thesis consist of: 62 p., 23 pictures, 4 tables, 34 bibliographical entries. Appendixes included.
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Sali, Mustapha. "Exploitation de la demande prévisionnelle pour le pilotage des flux amont d’une chaîne logistique dédiée à la production de masse de produits fortement diversifiés." Thesis, Paris 9, 2012. http://www.theses.fr/2012PA090037/document.
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Dans cette thèse, nous nous sommes intéressés au mode d’exploitation de la demande prévisionnelle pour le pilotage des flux amont dans un contexte de production de masse de produits fortement diversifiés et de dispersion géographique des unités de production. Lorsque l’information prévisionnelle est mal exploitée, des phénomènes, similaires à l’effet coup de fouet connu en chaîne logistique aval, apparaissent en chaîne logistique amont altérant durablement sa performance. Dans le but de contrer certains des mécanismes à l’origine de ces phénomènes, nous avons proposé une adaptation de la MRP permettant d’exploiter au mieux l’information prévisionnelle. L’adaptation de la MRP repose sur une méthode de calcul des besoins basée sur l’exploitation statistique des nomenclatures de planification et la diffusion d’informations sur les niveaux de recomplètement le long de la chaîne logistique amont. Cette approche a été testée avec succès sur plusieurs cas d’application dans l’industrie automobileIn this PhD dissertation, we investigated the way of exploiting the demand forecasts for the upstream flow management in a context of mass production of highly diverse products and of geographical dispersion of the production units. When the forecasts are poorly exploited, phenomena similar to the well-known bullwhip effect in the downstream supply chain appear in the upstream supply chain altering permanently its performances. In order to counter some of the mechanisms underlying these phenomena, we proposed an adaptation of the MRP to perform the exploitation of the forecasted demand. The adaptation of the MRP is based on a calculation method that uses the planning BOM for calculating and transmitting replenishment levels along the upstream supply chain. This approach has been successfully tested on several application studies in the automotive industry
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Ali, Mohammad Mojiballah. "Centralised demand information sharing in supply chains." Thesis, Bucks New University, 2008. http://bucks.collections.crest.ac.uk/10106/.
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This thesis explores Centralised Demand Information Sharing (CDIS) in supply chains. CDIS is an information sharing approach where supply chain members forecast based on the downstream member’s demand. The Bullwhip Effect is a demand variance amplification phenomenon: as the demand moves upstream in supply chains, its variability increases. Many papers in the literature show that, if supply chain members forecast using the less variable downstream member’s demand, this amplification can be reduced leading to a reduction in inventory cost. These papers, using strict model assumptions, discuss three demand information sharing approaches: No Information Sharing (NIS), Downstream Demand Inference (DDI) and Demand Information Sharing (DIS). The mathematical analysis in this stream of research is restricted to the Minimum Mean Squared Error (MMSE) forecasting method. A major motivation for this PhD research is to improve the above approaches, and assess those using less restrictive supply chain assumptions. In this research, apart from using the MMSE forecasting method, we also utilise two non-optimal forecasting methods, Simple Moving Averages (SMA) and Single Exponential Smoothing (SES). The reason for their inclusion is the empirical evidence of their high usage, familiarity and satisfaction in practice. We first fill some gaps in the literature by extending results on upstream demand translation for ARMA (p, q) processes to SMA and SES. Then, by using less restrictive assumptions, we show that the DDI approach is not feasible, while the NIS and DIS approaches can be improved. The two new improved approaches are No Information Sharing – Estimation (NIS-Est) and Centralised Demand Information Sharing (CDIS). It is argued in this thesis that if the supply chain strategy is not to share demand information, NIS-Est results in less inventory cost than NIS for an Order Up To policy. On the other hand, if the strategy is to share demand information, the CDIS approach may be used, resulting in lower inventory cost than DIS. These new approaches are then compared to the traditional approaches on theoretically generated data. NIS-Est improves on NIS, while CDIS improves on the DIS approach in terms of the bullwhip ratio, forecast error (as measured by Mean Squared Error), inventory holding and inventory cost. The results of simulation show that the performance of CDIS is the best among all four approaches in terms of these performance metrics. Finally, the empirical validity of the new approaches is assessed on weekly sales data of a European superstore. Empirical findings and theoretical results are consistent regarding the performance of CDIS. Thus, this research concludes that the inventory cost of an upstream member is reduced when their forecasts are based on a Centralised Demand Information Sharing (CDIS) approach.
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Nordeman, Niklas, and Malin Sundbäck. "An analysis on the benefits of information sharing in multi-echelon inventory control models." Thesis, Linköpings universitet, Logistik- och kvalitetsutveckling, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-138658.
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With growing markets and customers being geographically spread out, more pressure is put on a company’s logistics processes and their inventory structures are becoming more complex. This puts more pressure on the inventory control solution provided by a company like IFS, that supports their customers with inventory control through the Inventory Planning and Replenishment module in IFS Applications. As their customers’ supply chains grow larger, their inventory structures become more complex the next step is to find a solution for the IPR module more suitable in a called multi-echelon structure, i.e. several tiers of stock locations, such as local, regional and central warehouses. The purpose of this study is to compare a reorder point model with a solution suitable in a multi-echelon setting and investigate how they are able to manage uncertainties with service level targets. A literature study was performed, to find previous research on inventory control in multi-echelon inventory systems. In the literature study, the importance of coordination and information sharing between the echelons was emphasized and used as a focus when finding a suitable multi-echelon model. To answer the purpose a theoretical model was formulated from the findings in previous research, with a replenishment method suitable in a multi-echelon environment. The inventory control models also included lot sizing method and a safety mechanism, where the difference between the models were their respective replenishment policy. The theoretical model was based on the replenishment method Distribution Requirements Planning (DRP), as it enables information sharing, coordination and synchronization of the supply chain, while the other inventory control model uses the Reorder Point method (ROP). As information sharing was emphasized in previous research on multi-echelon systems, and the main difference between the two inventory control models is the information sharing in the DRP model, the important question to be answered with the comparison is; what effects and benefits can be achieved through information sharing in a multi-echelon inventory system? The two inventory control models were then simulated in Excel and exposed to even demand and seasonal variations in an inventory structure with three echelons and four sites, see figure below. When analyzing the results three evaluation criteria were used; difference in service levels, average inventory levels and if there were signs of overstocking in the regional and central warehouse, i.e. if the system was exposed to the bullwhip effect. The analysis was carried out based on the criteria above and divided into three sections. First, differences between the models for even demand were investigated. The same procedure followed for seasonal demand, identifying differences and what caused them. Findings were then summed up at the end of the chapter. For even demand, differences were small and sharing information does not give large benefits. Under seasonal demand though, sharing information proved to be very beneficial, reducing average inventory held in the system by 60%, compared to not sharing information. This because sharing information together with synchronizing eliminates the bullwhip effect. By testing different standard deviations, changing lead times and order quantities, using forecast or being blind to forecast, the robustness of the conclusions drawn from the analysis was put to the test. Carrying out a sensitivity analysis on the models served two purposes. First, finding more evidence promoting the benefits of synchronizing the supply chain and how important it is that the shared information is correct, otherwise the benefits are reduced. The second purpose was to validate that the models performed as expected when changing input data. The conclusions were the following: Information sharing enables synchronization of the supply chain Synchronization allows for reaching higher service levels with lower inventory levels Findings suggest that by sharing information, which must be the first step, synchronizing the inventory system is possible. It is the synchronization that creates the real benefits, such as higher service levels and lower inventory levels. However, the quality and accuracy of the shared information was found to play an important role. Sharing inaccurate or wrong information increase the risk of the system starting to suffer from the bullwhip effect, resulting in higher inventory levels and lower service levels.
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Paul, Somak. "Effect of Supply Chain Uncertainties on Inventory and Fulfillment Decision Making: An Empirical Investigation." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1563510590703363.
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Groll, Marcus Weber Jürgen. "Koordination im Supply Chain Management : die Rolle von Macht und Vertrauen /." Wiesbaden : Dt. Univ.-Verl, 2004. http://www.gbv.de/dms/zbw/394572424.pdf.
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Mangini, Eduardo Roque. "Análise investigativa do efeito chicote no desempenho logístico nas empresas do setor alimentício." Universidade Presbiteriana Mackenzie, 2007. http://tede.mackenzie.br/jspui/handle/tede/556.
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Previous issue date: 2007-02-07Supply chain involves all the activities associated to the handling of products since the very stage of raw materials up to the delivery of the manufactured goods to the final consumer which includes information sources and the attainment of these, the production schedule, processing order, inventory management, transportation, storage and costumer service. The relation of existing dependence among the participants of supply chain activities and resources causes consequences of negative nature when variation in any section or stage of the process occurs, phenomenon known as bullwhip effect. This phenomenon, also known as effect Forrester, is related with the increase of variation that occurs due to the up making of decisions related to political and organizational choices of investment front to the customers demand. The way the companies react to this whip effect, that is, the performance achieved is evaluated by the customers within aspects such as product quality, schedule reliability, order flexibility, delivery punctuality and last but not least a competitive final cost. These aspects are known as performance measures or competitive priorities. The main objective of this research is verifying the influence of the whip effect management within the food industry companies and the specific aim is mapping the generating features of the whip effect in this sector, besides, acknowledging the existence of such effect in levels of the supply chain and highlight the measures of control of the whip effect which are being used by the plants and also verifying the direct relationship of the bullwhip effect with the performance of everyone involved in the supply chain system. Research of qualitative and quantitative order has been lead in association with supermarkets of São Roque and Ibiúna area, quantitative surveys with the supermarkets as well as wholesale companies and Food processing companies. The results of the research point to the existence of the bullwhip effect, perceived and caused by the consumers, and amplified for the existence of promotion in the supermarkets companies, lack of sharing information among the companies of the supply chain as well as the absence of tools of electronic integration. The bullwhip effect observed also influences the performance of the organizations, mainly in flexibility and trustworthiness, affecting the Food processing companies corporative image.
A cadeia de suprimentos envolve todas as atividades associadas com a movimentação de produtos desde o estágio de matéria prima até a entrega do produto ao consumidor final, incluindo fontes de informações e obtenção destas, cronograma de produção, ordem de processamento, gerenciamento de inventário, transporte, armazenamento e serviço de atendimento ao cliente. A relação de dependência existente entre os participantes da cadeia de suprimentos, atividades e recursos causam conseqüências de natureza negativa quando ocorre variabilidade em qualquer sentido na cadeia de suprimentos, fenômeno este conhecido como efeito chicote. Este fenômeno, também conhecido como efeito Forrester, está relacionado com a amplificação e variabilidade que ocorrem pela antecipação de decisões, políticas, formas organizacionais e escolha de investimento frente a demanda dos consumidores. O modo como as empresas reagem ao efeito chicote, ou seja, o desempenho apresentado, é avaliado pelos clientes nos aspectos relacionados com qualidade de produtos, confiabilidade no prazo estipulado, flexibilidade com relação à quantidade, agilidade ou velocidade na entrega e um preço competitivo, o que sugere um baixo custo geral. Esses aspectos, são conhecidos como medidas de desempenho ou prioridades competitivas. O objetivo principal deste trabalho foi verificar a influência do gerenciamento do efeito chicote nas empresas relacionadas com a indústria alimentícia, e os objetivos específicos foram mapear os fatores que promovem o efeito chicote na indústria alimentícia, verificar a presença do efeito chicote nos vários níveis da cadeia de suprimentos e destacar fatores de controle do efeito chicote que estão sendo utilizados pelas empresas, além de verificar o relacionamento do efeito chicote com o desempenho dos participantes dessa cadeia de suprimentos. Foram conduzidas pesquisas de natureza qualitativa e quantitativa com empresas supermercadistas da região de São Roque e Ibiúna e pesquisas quantitativas com os clientes das empresas supermercadistas bem como com empresas atacadistas e fabricantes de produtos alimentícios. Os resultados das pesquisas apontam para a existência do efeito chicote, percebido e ocasionado pelos consumidores, e amplificado pela existência de promoção nas empresas supermercadistas, falta de compartilhamento de informações entre as empresas da cadeia de suprimentos bem como pela ausência de ferramentas de integração eletrônica. O efeito chicote observado, influencia também o desempenho das organizações, principalmente na flexibilidade e confiabilidade, afetando a imagem corporativa das empresas da indústria alimentícia.
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Lu, Ju-Chiung, and 盧儒瓊. "The Study of Forecast on Bullwhip Effect." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/87378432155811040950.
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碩士國立交通大學
工業工程與管理系
89
Due to the frequent and fierce global trades nowadays, issues of the supply chain management are getting more and more popular. Enterprises want to deliver their customers products of the right quantity and quality in the right place and on the right time by utilizing the supply chain management practices. There is one common phenomenon in the supply chain called “Bullwhip Effect”. The so-called Bullwhip Effect is that tiny changes of the demands downstream will cause enormous fluctuation upstream. The closer to the upstream, the bigger fluctuation. This thesis discusses the influence of forecast periods and forecast methods on the Bullwhip Effect. The model of the supply chain used here is a straight-line and simplified one, including one retailer, one wholesaler, one manufacturer and one supplier. With the combinations of two forecast periods and three forecast methods, it produces six scenarios. These scenarios are employed to simulate the possible demand forecasts and behaviors within each layer in the supply chain. Design of Experiment (DOE) is then adopted to analyze the data collecting through simulation. The experimental results indicate that the forecast indeed affect Bullwhip Effect. In addition, the combinations of forecast periods and methods also influence the Bullwhip Effect to certain extent.
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黃富聰. "The Bullwhip Effect in Multi-Echelon Supply Chains." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/32690159477350898299.
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Lin, Yue-Yi, and 林岳毅. "A Study of Factors on the Bullwhip Effect." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/64705759127836473160.
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碩士國立臺中技術學院
事業經營研究所
95
It’s necessary to pay attention to countermeasures against the bullwhip effect because the efficiency of supply chain can be reduced by the phenomenon. According to the viewpoint of “demand signal processing”, this study attempted to investigate factors affecting the bullwhip effect from the demand process and ordering process. A three-echelon supply chain system was considered and it was simulated on the worksheets of Microsoft Excel. Assuming that customer demands were described by a ARIMA(p,0,q) process, and the demand process consists of four parameters including the autoregressive coefficient, the moving-average coefficient, the constant, and the standard deviation of the error term. The ordering process also consists of four parameters, and they are the lead times of the wholesaler, the forecasting methods, the service levels, and the demand information. Based on these parameters, this study designed a full-factor experiment for the collection of the bullwhip data and then employed a statistical software named STATISTICA to analyze these data. We can then understand how the factors affect the bullwhip. Three models of low-level ARIMA(p,0,q) and three combinations of forecasting parameters were considered. In every full experiment, one ARIMA(p,0,q) model was arranged in pairs with one combination of forecasting parameters, hence the operations of full experiment totaled to 9 times. The analytic results of these experiments were compared with each other. The conclusions could be stated as follows briefly: (1) The autoregressive coefficient affects the bullwhip negatively. (2) the moving-average coefficient affects the bullwhip positively. (3) The “anti-bullwhip effect” doesn’t appear when the autoregressive coefficient is smaller than the moving-average coefficient. (4) The bullwhip effect will be amplified more when we forecast future demands with exponential smoothing rather than moving average. (5) The more demand information used to construct the forecast, the smaller the bullwhip effect. (6) The increase in variability will be greater for longer lead time. (7) The bullwhip effect always happens if the supply chain members had to forecast future demand.
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Wu, Ping-heng, and 吳秉衡. "Bullwhip effect in supply chain based on chaotic demand." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/49502408190563126930.
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碩士國立成功大學
工業與資訊管理學系碩博士班
95
Supply chain management is getting more important to an enterprise because of the blooming international business and the intensive competition. The efficient SCM can create common benefit among suppliers, distributors, retailers, and other firms within the supply chain. Bullwhip effect is a well known phenomenon in the supply chain and it makes the order costs or the holding costs of the members in the supply chain increasing. Previous researches haven't profoundly studied the bullwhip effect based on chaotic demand. Thus, this research will study the bullwhip effect based on chaotic demand in a supply chain. In this study, we use the adjusted Mackey-Glass equation as the demand model, and the best order quantity that makes the expected inventory up to the target inventory is obtained. Finally, the main cause of the bullwhip effect based on chaotic demand is found by using the demand model and the supply model. Through empirical analysis, it is found that the major factor of the bullwhip effect with chaotic demand is lead time. The longer the length of lead time is, the more distinct the bullwhip effect is. Finally, the acceptable scope of lead time and the parameters of the model by using sensitive analysis are obtained.
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唐志軒. "The Study of Bullwhip Effect in Supply Chain Management." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/05692579831091477167.
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碩士國立臺灣科技大學
工業管理系
88
An important observation in supply chain management, known as the bullwhip effect, suggests that demand variability increases as one moves up a supply chain. The information transferred in the form of "orders" tends to be distorted and can misguide upstream members in their inventory and production decisions. The bullwhip effect can lead to tremendous inefficiencies：excessive inventory investment, poor customer service, lost revenues, misguided capacity plans, ineffective orderings, missed production schedules. In this paper we have demonstrated that the causes of the phenomenon. And this study constructs two models：（1）use two different demand forecasting methods；（2）use three kinds of ordering policies. We have shown that the causes of bullwhip effect by our models. According to proposed models, managers may reasonably regulate demand forecasts and determine the suitable strategies for absorbing the uncertainty of demands. Today, supply chain management must reverse a traditionally adversarial relationship with using the rapid development and evolution in information technology, information sharing has to be timely and accurate. The supply chain management has received vertical integration and horizontal collaboration.
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鄭碧鈺. "The Influence of Information Transfer Model to Bullwhip Effect." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/39942730914638159154.
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碩士逢甲大學
工業工程與系統管理學系
104
In supply chain management, the bullwhip effect problem has yet to be solved. Each stage in the supply chain is linked with the next, and the bullwhip effect is susceptible to the impact of demand forecasts, price fluctuations, and batch ordering. Thus, when change happens downstream, it will affect the next link in the chain, and the fluctuations become distorted further upstream. How to reduce the impact caused by the bullwhip effect is still worthy of in-depth exploration. In the days of Industry 4.0, the Internet of Things, and Big Data, information delivery is more rapid. Therefore, we will use the concept of the Internet of Things to meet the demand for delivering messages more quickly. The purpose of this study is to discuss the comparison between the traditional means of feedback and instant feedback methods under the condition of Industry 4.0 in supply chain management. Using the Plant Simulation system, two kinds of feedback transmission models were simulated under differing consumer demand to compare their effects on the bullwhip effect. According to the results of this simulation, the bullwhip effect was much stronger in the traditional feedback method compared to that of the instant feedback method at every stage except for the retail stage, regardless of consumer demand. That is, the instant delivery method can substantially reduce and possibly even eliminate the bullwhip effect in the supply chain.
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Lu, Hsiao Chun, and 盧曉君. "Study On Partnership Of Supply Chain In Bullwhip Effect." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/59085634549914181033.
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碩士元智大學
管理研究所
97
The advance technology brings up the economical globalization. Therefore, the supply chain management faces the competitive marketing more complicated, which rise up the uncertain factors in all environment. As the reasons, to react the customer’s needs in the short time will shrink the products lead time so that the life cycle of products will absolutely cut down cause it has the new design produced now and then. That could make the most torment problems “Bullwhip Effect” in SCM. The research is based on regression analysis to explore the four factors in bullwhip effect which have forecasting need、ordering volume、fluctuating price、lead time, and three factors in partnership which have trust、promise and elasticity variables. Regarding all of factors in partnership depend on each other and also in cooperation. Changing the factors of bullwhip effect is active on partnership and strengthen partnership can diminish the bullwhip effect. To hope via the research can know how to consolidate supply chain management issues. The study samples are sales background in electronics industry and by questionnaire. The research found out when change the bullwhip effect factors such as forecasting need、ordering volume、fluctuating price、lead time issues that are remarkable effect on that, and improving the partnership’s elasticity in SCM will be outstanding in reducing bullwhip effect to cause the damage. The research can offer the good partnership of importance in the field, not only create the longer competitive advantages, but also can know other ways to reduce the loss in the bullwhip effect.
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Simões, Angela Isabel Mendes. "The impact of Replenishment Policies in the Bullwhip Effect." Master's thesis, 2019. http://hdl.handle.net/10316/97276.
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Dissertação de Mestrado em Engenharia e Gestão Industrial apresentada à Faculdade de Ciências e TecnologiaO efeito de chicote descreve o fenómeno da amplificação da procura ao longo de uma cadeia de abastecimento. Esta amplificação gera grandes consequências para as empresas, tais como previsões incorretas da procura, grandes custos de inventário e falhas no nível de serviço prestado.Tudo isto leva a que haja grande pressão sobre os gestores para que estejam cientes de quais os fatores que causam efeito de chicote, bem como para que minimizem os mesmos. Torna-se assim importante perceber se os algoritmos de reaprovisionamento utilizados estão a contribuir para este efeito e qual o seu impacto. Esta dissertação aborda a lacuna de pesquisa existente sobre a avaliação do impacto de algoritmos de abastecimento no efeito de chicote através do uso da simulação de eventos discretos. Foi simulada uma cadeia de abastecimento com quatro elos, que fornece apenas um produto, tendo sido testados quatro algoritmos de reabastecimento.Os resultados da simulação revelam alterações ao nível da média e desvio padrão da procura, assim como nos níveis de inventário, indicando assim a presença do efeito de chicote. Durante a avaliação de resultados foi ainda possível apoiar as teorias de Disney et al. (2005) e Pozzi et al. (2018), Potter & Disney’s (2006, apud Bhattacharya & Bandyopadhyay, 2011) e Potter & Disney (2006) relacionadas com o impacto do lead time, do tamanho do lote e do tempo entre encomendas, respetivamente, na amplificação da procura.Os resultados mostram que, nas condições testadas, a escolha do algoritmo de reabastecimento tem efeito sobre o efeito de chicote experienciado pela cadeia.Investigação futura poderá ser feita no sentido de validar esta descoberta em diferentes estruturas de cadeias de abastecimento, bem como diferentes níveis de procura. Caso venha a ser validada, existe a possibilidade de se poder desenvolver uma ferramenta de apoio à tomada de decisão que guie os gestores na escolha do algoritmo mais adequado à sua cadeia.
The Bullwhip Effect describes the phenomenon of amplification of demand throughout the supply chain and brings great consequences to a company such as failure to predict the real demand, large inventory costs and poor customer service. As managers are urged to be aware of all the factors that contribute to this problem and minimize them as much possible, it’s important to understand if the used replenish algorithms can be a cause of bullwhip and what is its impact. This dissertation addresses the gap related to assessing the impact of replenishment algorithms in the bullwhip effect through the use of discrete-event simulation, by simulating a 4-echelon supply chain, serving a single product, under four different replenishment strategies.It was possible to clearly identify changes in the average demand, demand standard deviation and inventory levels that confirmed the existence of bullwhip effect. During the data analysis, it was also possible to support the theories of Disney et al. (2005) and Pozzi et al. (2018), Potter & Disney’s (2006, apud Bhattacharya & Bandyopadhyay, 2011) and Potter & Disney (2006) related to the impact of batch sizes, lead time and time between orders, respectively, in the bullwhip effect. In the end, results found that, under the studied conditions, the choice of replenishment algorithm does influence the bullwhip experienced by the chain.Further research is needed to validate these findings under a broader range of demand patterns and supply chain configurations. If these findings are proven to be valid there’s a possibility to develop a managerial tool in order to help guide the decision of choosing replenishment algorithms in supply chains.
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Chiu, Chien-ming, and 邱乾銘. "The Study on the Bullwhip Effect in Supply Chain Management." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/28953774768735962380.
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碩士國立高雄第一科技大學
運輸倉儲營運所
92
In this rapid changing era, the globe trade are getting frequently. In the past, what the enterprise needs to do for their clients is to make a response to their customers’ request. However, under the drastic competition among global marketplace, the enterprise must have skills to deal with uncertainty because the response time and the life cycle of commodity are getting short continuously. Most of the famous firms expect to enhance the standard of service and the quality of merchandise through effective management of supply chain, and “Bullwhip Effect” is a baffling problem to everyone. The phenomenon of demand ordering variability in the supply chain were amplified (information distortion) as they moved upsteam the supply chain is called “bullwhip effect”. This research adopts optimum stock mode to infer a mathematic mode to ships present the phenomenon of multi-echelon bullwhip effect, and discuss the relation among every echelons；also, utilize information share to reduce the bullwhip effect. Many enterprises have spent lots of capital in improving the information flows to reduce the environmental uncertainty of supply chain. How much the information having been shared among the different parties, under what kind of circumstances will the profit be initiated and when will the optimum price-earning ratio be reached are indeed issues in association with supply chain management to be explored. So that enterprise may avoid investing in incorrect directions and enhancing their business competitiveness.
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Zhang, Jia-Ming, and 張家銘. "The study of solving the bullwhip effect of supply chain." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/41795365557258246266.
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碩士明新科技大學
工程管理研究所
92
There is one common situation in the Supply Chain (SC) called “Bullwhip Effects”. The Bullwhip Effects is described as “little changes of the demands from downstream of SC will cause great fluctuation to upstream of SC”, the closer to the upstream of SC, the fluctuation is greater. Bullwhip Effect can cause excess inventory, shortage of stock, variation of production forecast, low customer service level…et. This thesis provided a systematic mathematical analysis with application of EXCEL software, the supply chain model considered in this thesis contains 1 supplier, 1 manufacturer, 2 distributions, 3 retailers and 6 customers. The factors which impact the analytic model are lead time, lot policy and order policy, and the major evaluation criteria are inventory level and shortage stock quantity both in respects of average and standard deviation. For system simplicity, we assumed every customer’ demand satisfy the normal distribution with mean 100 and S.D. 20, T-test is also used to test whether each pairs (analysis model) is significant difference. This thesis would get 5 conclusions. 1. The variation of order quantity will influence inventory level. 2. Lead time reduction can reduce influence of bullwhip effects. 3. As-required (no batch) policy is better for inventory reduction and batch policy is better for shortage prevention. 4. Moving Average model cause smooth and steady ordering status thus reduces almost in every situation. 5. In summary, the model (LT=2、As-required、MA) is the best.
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Chang, Ling-Yu, and 張玲玉. "Strategy for bullwhip effect during financial crisis - X company case." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/94534835859327590372.
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碩士國立中央大學
工業管理研究所碩士在職專班
99
The economic downturn has brought a lot of turmoil in every industry around the world. In Taiwan’s semiconductor industry, there’s serious impact on IC design house, foundry service, assembly and testing house. In this semiconductor supply chain, every firm faces an unavoidable bullwhip effect. Because the demand of consumer product is low, the firm in the lower stream of the supply chain cuts the orders to the foundry service. The variance of order is huge and the bullwhip effect is significant when the firm is in the upper stream of the supply. The purpose of this study is to provide the suggestions to eliminate the impact of bullwhip effect during the recession. By using the technique of SWOT and five force analyses, the company can find the best strategy to stake out a position in the industry. Also, to have the knowledge of company’s capability and of the causes of competitive forces will emphasize the areas where the company should confront competition and where should avoid it. Furthermore, developing e-commerce to enhance the customer relationship management increase the potential benefits for the firm and the customer.
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Shyu, Show-Jenq, and 徐壽政. "A Comprehensive Model for Analyzing the Scenarios of Bullwhip Effect." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/30400483607886503549.
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碩士國立交通大學
工業工程與管理研究所
86
Due to serious competition of the business environment, enterprises pay more attention to supply chain management. An important issue of supply chain management is to match the production rate to the actual sales rate from the consumers. However, a small fluctuation of demand in reail stores always causes higher demand fluctuation in its upstream. The phenomenon is known as the “bullwhio effect,” this effect is a great threat to an enterprise. The bullwhip effect has been studied for several years, but there exits no comprehensive for its analysis. Therefore, this study proposed a comprehensive model for analyzing the scenarios of bullwhip effect. The model divedes the causes of bullwhip effect into three parts: the structure of a supply chain, decision makings of indiviual echelon, and customer demand. Each part could be extended to involve more detail factors. Also, we can construct a proper scenario according to the characteristics of a supply chain, and then analyze the Bullwhip Effict step by step. It makes managers realize how their decision affects a supply chain, and helps them make better decisions to maximize profits and enhancing to enterprise productivity.
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Cho, Cheng-Hsien, and 卓政憲. "Identifying Key Supply Chain Agility in Response to Bullwhip Effect." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/ja858j.
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碩士國立虎尾科技大學
工業管理系工業工程與管理碩士班
106
In the face of global competition and rapid market changes, enterprises must lay emphasis on how to set up effective supply chain management strategies in order to resolve problems faced by enterprises. However, for many enterprises, the problem of bullwhip effect in the supply chain has a negative impact difficult to overcome in supply chain management. Scholars have pointed out that agility can effectively inhibit the bullwhip effect. However, how to utilize agility strategies and advantageously respond to the bullwhip effect has so far not been proposed. The purpose of this study is to evaluate the key criteria of agility that inhibits the impact of the bullwhip effect through the advantage of agility that quickly responds to the market, thereby alleviating impacts arising from the bullwhip effect in the supply chain. This study adopted one TAIEX listed company in Taiwan as the empirical research participant to explore the key criteria of agility in the supply chain in response to the bullwhip effect. Based on the literature review, the factors causing the bullwhip effect and the supply chain agility criteria were compiled. Additionally, through the analysis of the key factors and criteria, the degree of importance of agility in alleviating the impact of the bullwhip effect, as well as the mutual relatedness of the factors were evaluated, thereby providing supply chain managers with the key criteria for analyzing and responding to the bullwhip effect of agility. This study adopted the quality function deployment (QFD) as the basic framework. First, through fuzzy Delphi method (FDM), the important factors contributing to bullwhip effect and agility were screened and selected. Then, the fuzzy interpretative structural model (FISM) was employed to explore the interrelatedness among the bullwhip factors that possibly existed. Then, through the analytic network process (ANP), the relevance and weight of the bullwhip effect were analyzed. Finally, gray relational analysis (GRA) was used to obtain selection results. Furthermore, the results obtained from Fuzzy Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) and VlseKriterijumska Optimizacija I Kompromisno Resenje (VIKOR) were compared with the GRA results in order to serve as a reference for enterprise managers during decision-making.
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劉家豪. "Analyzing the Bullwhip Effect in Supply Chain by Empirical Mode Decomposition." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/26225975173035803766.
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Chang, Chia-yen, and 張嘉晏. "The Strategies to Counter the Bullwhip Effect: OEM/ODM asan Example." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/22117884468307046213.
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碩士大同大學
事業經營學系(所)
93
Supply chains often involve linkages among many firms. Each firm depends on other firms for materials, components, services, and information needed to supply its immediate customer in the chain. Because firms typically are owned and managed independently, the actions of downstream members (toward the ultimate user of the product or service) of the supply chain can adversely affect the operations of upstream members (toward the lowest tier in the supply chain). Minor disturbances in end demand can translate into huge disturbances at upstream suppliers. These dynamics are often referred as the bullwhip effect. This bullwhip effect has traditionally been accepted as an inevitable part of doing business in the electronics industry. The bullwhip effect occurs when demand order variabilities in the supply chain are amplified as they moved up the supply chain. Distorted information from one end of a supply chain to the other can lead to tremendous inefficiencies, including: poor product forecasts, piles of inventory, poor customer service due to unavailable products or long backlog, misguided capacity plans, and missed production schedules. Bullwhip effect exists in every manufacturing industry. When a downstream operation places an order, the upstream manager processes that piece of information as a signal about future product demand. Based on this signal, the upstream manager readjusts his or her demand forecasts and, in turn, the orders placed with the suppliers of the upstream operation. Therefore, the orders placed by the more upstream entity in the supply chain have much greater variability. Distorted information has led every entity in the supply chain to stockpile because of the high degree of demand uncertainties and variabilities. Companies can effectively counteract the bullwhip effect by thoroughly understanding its underlying causes. Therefore, the purposes of this study are: First, to explore the causes of bullwhip effect and countermeasures by literature review. Second, using empirical study to verify the relative importance of factors causing the bullwhip effect and countermeasures. Third, based on the result of literature review and empirical study, this study will poses solid suggestions to the manufacturers for improving the bullwhip effect in their supply chain. The causes of the bullwhip effect identified by authors include: demand forecast updating, order batching, price fluctuation, and rationing and shortage gaming. This study will use OEM/ODM manufacturers as empirical research subjects. The empirical data will collect by using a mail questionnaire and will be analyzed by using AHP (Analytical Hierarchical Process Method). Along with the globalization, enterprise must collaborate with the supply chain network partners. So it is a necessary element for survival to well operate in the supply chain to quickly get in touch with the market, to decline the inventory risk and cost presses and to quick response. In order to satisfy the consumer requirement, promise to fulfill all orders on time, quickly respond the market, avoid the lack of materials or insufficient capability. Improving the bullwhip effect of the supply chain,the Vendor Managed Inventory (VMI) is the best method. It can share the inventory information with vendor and purchaser to manage the customer’s inventory level.
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TSUNG, CHENG YING, and 鄭穎聰. "The study of Sloving the Bullwhip Effect of Supply Chain Policy." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/70535821312918970507.
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碩士國立臺北科技大學
生產系統工程與管理研究所
88
Base on literature overview the causese of bullwhip effect of Supply Chain include time delay, batch of production and ordering, echelon number of supply chain, the price policy. This paper defines three sections for the causese of bullwhip effect of Supply Chain. Firstly, It studies about three kinds production environment to influence time delay and echelon number of causese of bullwhip that are MTS, MTO & ATO；Secondly, it usese inventory policy by (s,S) ,(s,Q) ,(s,S,R) ,(s,Q,R) & VMI; 3th share sales information for every echelon of supply chain. It could reduce forecasting error. System dynamic methodology was used to construct and simulation policy models. This paper makes six performance indexs that are service level, cycletime, turn rate of goods, turn rate of parts, deliver number & order number. Finally, the paper the grey relational analysis methodology was used to optimize the policy factors in different customer’s requirement types. The study used grey relational analysis that found ATO and (s,S) optimal supply chain performance index policy, MTO and (s,S) optimal bullwhip effect index policy in step demand type; ATO and VMI optimal supply chain performance index policy, MTO and VMI optimal bullwhip effect index policy in season demand type; ATO and (s,S) optimal supply chain performance index policy, MTO and (s,S) optimal bullwhip effect index policy in rise trend demand type; ATO and (s,S) optimal supply chain performance index policy, ATO and VMI optimal bullwhip effect index policy in decrease demand type.