international sourcing and supply chain stability an international supply chain is conceptualized as a complex dynamic system in which disruptions interact with long shipping and lead times to generate costs findings from a case study and simulation model indicate that demand related disruptions created substantial and unexpected costs in terms of expedited shipping high inventories and lower demand fulfillment production related disruptions declined over time but demand related disruptions did not implications for management are discussed

the energy and co2 emissions impact of renewable energy development in china the authors are grateful for the support provided by the national key technology r d program from ministry of science and technology of grant no 2012bac20b07 we acknowledge the support of the national key technology r d program and the institute for energy environment and economy at tsinghua university which is supporting tianyu qi s doctoral research as a visiting scholar at the massachusetts institute of technology we acknowledge the support of eni icf and shell initial founding sponsors of the china energy and climate project this consortium of sponsors has provided support for researchers in the mit joint program to engage in a five year program of research focused on china none of the sponsoring organizations played a role in the study design collection analysis or interpretation of the data used for this study nor did they influence our decisions to submit the article for publication and all errors are our own

the analysis of bullwhip effect in a hmms type supply chain the aim of the paper is to investigate the well known bullwhip effect of supply chains control theoretic analysis of bullwhip effect is extensively analyzed in the literature with the laplace transform this paper tries to examine the effect for an extended holt modigliani muth simon model a two stage supply chain supplier manufacturer is studied with quadratic costs functional it is assumed that both firms minimize the relevant costs the order of the manufacturer is delayed with a known constant two cases are examined supplier and manufacturer minimize the relevant costs decentralized and a centralized decision rule the question is answered how to decrease the bullwhip effect

production chains and aggregate output volatility abstract a production chain s aggregate output volatility depends upon a number of factors including the number of firms in a chain the management strategy of the firms the point at which products are differentiated lead times and the persistence of demand shocks the influence of these factors is quantified here with an n firm model of the production chain under pure production to stock pts the firms in the chain respond simultaneously to a demand shock producing a positive covariance across firms that raises aggregate volatility under production to order pto the chain s response to a demand shock is staggered but when demand shocks are persistent there is a catch up effect that raises the volatility of each firm s production above that of a firm that under pts nevertheless pto chains typically exhibit less volatility than pts chains thanks to the covariance effect further simulations demonstrate that the production chain stabilizes as the number of production cycles in an observation period increases

the bullwhip effect in supply chains an overestimated problem abstract a phenomenon that is now well known as the bullwhip effect suggests that the variability of orders increases as they move up the supply chain from retailers to wholesalers to manufacturers to suppliers in this paper we will focus mainly on measuring the bullwhip effect existing approaches that aim at quantifying the bullwhip effect neglect the network structure of supply chains by only assuming a simple two stage supply chain consisting of a single retailer and a single manufacturer some of the relevant risk pooling effects associated with the network structure of supply chains are disregarded risk pooling effects arise when the orders which a retailer receives from its customers are statistically correlated with a coefficient of correlation less than one when analyzing the bullwhip effect in supply chains however the influence of risk pooling has to be considered the fact that these influences have not yet been analyzed motivates the research presented in this paper we will show that the bullwhip effect is overestimated if just a simple supply chain is assumed and risk pooling effects are present

a chinese sky trust distributional impacts of carbon charges and revenue recycling in china abstract the introduction of carbon charges on the use of fossil fuels in china would have a progressive impact on income distribution this outcome which contrasts to the regressive distributional impact found in most studies of carbon charges in industrialized countries is driven primarily by differences between urban and rural expenditure patterns if carbon revenues were recycled on an equal per capita basis via a sky trust the progressive impact would be further enhanced low income mainly rural households would receive more in sky trust dividends than they pay in carbon charges and high income mainly urban households would pay more than they receive in dividends thus a chinese sky trust would contribute to both lower fossil fuel consumption and greater income equality

deliberating on renewable and sustainable energy policies in china abstract in order to realize the sustainable development of country and society many countries have established their renewable energy law and development strategy no matter developed countries or developing countries it is well known that china is the largest developing country in the world and the per capita gdp ranks more than 100 however the total gdp ranks the second due to the huge population amount and just behind usa certainly the total energy consumption amount is huge and the big energy demand has brought a serious of environmental problems such as acid rain water and soil pollution and resource exhaustion etc fortunately china central government has regarded the serious question to realize the sustainable development in future the renewable energy law has been established in 2005 firstly china s energy situation and existing environmental questions in past years is introduced in this paper secondly the distribution and the application practice of different renewable energy were introduced then china s renewable energy policy is detailed introduced in the following section the next section discusses the existing questions based on these discussions the development barriers and recommendations are introduced respectively

evaluating alternative capacity strategies in semiconductor manufacturing under uncertain demand and price scenarios abstract because product demand is very volatile and machine and process technologies are advanced at a rapid pace capacity planning and investment in the semiconductor industry is a challenging task many studies have addressed mid and short term machine portfolio planning tasks of capacity planning however capacity planning should be considered in a framework of strategy planning in order to address the whole problem this paper describes a method of analysis for adapting capacity strategy to changing business environment the paper has three major parts in the first part empirical data analysis of a case study company yields predictive formulas for production and capacity costs the uncertainty of demand is also calibrated using the geometric brownian motion process in the second part experiments are designed to simulate demand and profit scenarios for comparing two capacity strategies in the third part the resultant data of simulation are analysed to gain insights to the relative performance of the two strategies in various scenarios the analysis method provides a framework for formulating capacity strategy and for integrating capacity planning with business planning

the effect of inventory record inaccuracy in information exchange supply chains abstract the goal of this paper is to quantify the impact of inventory record inaccuracy on the dynamics of collaborative supply chains both in terms of operational performance i e order and inventory stability and customer service level to do so we model an information exchange supply chain under shrinkage errors in the inventory item recording activity of their nodes present the mathematical formulation of such supply chain model and conduct a numerical simulation assuming different levels of errors results clearly show that inventory record inaccuracy strongly compromises supply chain stability particularly when moving upwards in the supply chain important managerial insights can be extracted from this analysis such as the role of benefit sharing strategies in order to guarantee the advantage of investments in connectivity technologies

a supply chain as a series of filters or amplifiers of the bullwhip effect abstract the bullwhip effect refers to the phenomenon of amplification and distortion of demand in a supply chain by eliminating or controlling this effect it is possible to increase product profitability reducing useless costs such as stock out and obsolescence costs the main focus of this work is to study a single product serial supply chain in which a control parameter can switch the chain from a series of filters to a series of amplifiers of the bullwhip effect and to analyse how the optimal values of the parameters change when discontinuities in order policy are considered furthermore it is also shown that the bullwhip itself it is not a good index of the chain s performance because it does not consider the oscillations that occur in the inventories which also may affect the supply chain performance

the production and inventory behavior of the american automobile industry understanding inventory movements is central to an understanding of business cycles this paper presents an empirical study of the behavior of inventories in the automobile industry it finds that inventory behavior is well explained by the assumption of intertemporal optimization with rational expectations the underlying cost structure appears to have substantial costs of changing production as well as substantial costs of being away from target inventory thelatter being a function of current sales given this cost structure whether inventory behavior is stabilizing or destabilizing depends on the characteristics of the demand process in the automobile industry inventory behavior is destabilizing the variance of production is larger than the variance of sales

small sample uncertainty aspects in relation to bullwhip effect measurement abstract the bullwhip effect as a concept has been known for almost half a century starting with the forrester effect the bullwhip effect is allegedly observed in many supply chains and it is generally accepted as a potential malice despite this the bullwhip effect still seems to be first and foremost a conceptual phenomenon some even simply denies that the phenomenon exists at all in practice this of course makes it important to perform measurements because only what gets measured gets done as the saying goes in analytics few measurements are reported in the literature however typically based on standard statistical assumptions in the case of a standard measurement of the bullwhip effect independence amongst the participating variables are required amongst others but this is definitely known not to be perfectly true if any systematic control at all have taken place in the supply chain this paper analyses the bullwhip measurement implications in case the standard test assumptions are violated and illustrates how to improve on the testing setup this is further done with a special emphasis on the unavoidable small sample aspects relating to such measurement in practice which typically renders all statistical asymptotic or robust arguments quite unusable it is shown how h 0 95 confidence test intervals still easily can be obtained numerically in such cases

a human experiment on inventory decisions under supply uncertainty abstract controlled human experiments are adopted in this paper to investigate the impact of supply uncertainty on buyers inventory management the experiments aim at assessing the impact of one specific source of supply chain uncertainty namely stochastic lead times on inventory holdings and the extent of the bullwhip effect three experimental treatments are run within the framework of the beer game manipulating variability in demand and in lead times results confirm that the bullwhip effect arises in all experimental treatments and that the variance of orders is higher under stochastic lead times analysis of players behaviour in the course of the game suggests that players react to higher uncertainty by holding fewer inventories a behaviour consistent with the predictions of some psychological models of choice under ambiguity

information distortion in a supply chain the bullwhip effect this article originally appeared in management science april 1997 volume 43 number 4 pp 546 558 published by the institute of management sciences consider a series of companies in a supply chain each of whom orders from its immediate upstream member in this setting inbound orders from a downstream member serve as a valuable informational input to upstream production and inventory decisions this paper claims that the information transferred in the form of orders tends to be distorted and can misguide upstream members in their inventory and production decisions in particular the variance of orders may be larger than that of sales and distortion tends to increase as one moves upstream a phenomenon termed bullwhip effect this paper analyzes four sources of the bullwhip effect demand signal processing rationing game order batching and price variations actions that can be taken to mitigate the detrimental impact of this distortion are also discussed

the bullwhip effect progress trends and directions the bullwhip effect refers to the phenomenon where order variability increases as the orders move upstream in the supply chain this paper provides a review of the bullwhip literature which adopts empirical experimental and analytical methodologies early econometric evidence of bullwhip is highlighted findings from empirical and experimental research are compared with analytical and simulation results assumptions and approximations for modelling the bullwhip effect in terms of demand forecast delay replenishment policy and coordination strategy are considered we identify recent research trends and future research directions concerned with supply chain structure product type price competition and sustainability

closed loop supply chains what reverse logistics factors influence performance this paper analyses the inventory and order flow dynamics in closed loop supply chains clscs in this kind of supply chains the reverse flow of materials entering the system for recycling purposes complicates the way in which inventories should be managed and replenishment policies should be designed specifically we analyse the relationships between some reverse logistics factors remanufacturing lead time return rate of recycled products reverse order policy and number of supply chain tiers on the order and inventory variance amplification we firstly perform a systematic literature review of the related studies secondly by adopting a difference equation math approach and design of experiment we perform a robust what if analysis of a clsc under a variety of operational and market conditions results show that ceteris paribus clsc outperforms a forward supply chain both in mono echelon and multi echelon structures and under both stationary and turbulent market demands furthermore reducing remanufacturing lead time and promoting information transparency may be crucial to improve clsc dynamics finally we use the research findings to provide interesting managerial consideration about how to reduce unnecessary operational members costs

the role of forecasting on bullwhip effect for e scm applications abstract the bullwhip effect represents the information distortion in customer demand between orders to supplier and sales to the buyer demand forecasting is one of the main causes of the bullwhip effect the purpose of this study is to analyze the impact of exponential smoothing forecasts on the bullwhip effect for electronic supply chain management e scm applications a simulation model is developed to experiment the different scenarios of selecting right parameters for the exponential smoothing forecasting technique it is found that longer lead times and poor selection of forecasting model parameters lead to strong bullwhip effect in e scm in contrast increased seasonality helps to reduce the bullwhip effect the most significant managerial implication of this study lies in the need to reduce lead times along the e supply chain to mitigate the bullwhip effect while high seasonality would reduce the forecast accuracy it has a positive influence on the reduction of bullwhip effect e scm managers are therefore strongly suggested to utilize exponential smoothing by selecting lower values for and and a mid value for to keep the bullwhip ratio low while at the same time to increase forecast accuracy

transfer function analysis of forecasting induced bullwhip in supply chains the present paper analyses the bullwhip problem generated by exponential smoothing algorithms in both stand alone passing on orders mode and within inventory controlled feedback systems results are predicted from transfer function analysis and then confirmed by simulation via the bullwhip explorer supply chain software a novel feature of the paper is the introduction of the matched filter concept into the exponential smoothing algorithm this adjusts the value of the smoothing constant depending on whether the constant linear or quadratic forecasting model is used it is shown that matching the filter via noise bandwidth equalises the output variance when the demand is a random signal hence some of the unwanted effects of using the linear and quadratic forecasting models are attenuated however there is little benefit obtained by using sophisticated forecasting methods within inventory controlled feedback systems as their tracking ability is reduced

managing the trade off implications of global supply abstract the cost versus response trade off is a growing logistics issue due to many markets being increasingly characterised by demand uncertainty and shorter product life cycles this is exacerbated further with supply increasingly moving to low cost global sources however the poor response implications of global supply are often not addressed or even acknowledged when undertaking such decisions consequently various practical approaches to minimising postponing or otherwise managing the impact of the demand uncertainty are often only adopted retrospectively even though such generic solutions are documented through case examples we lack effective tools and concepts to support the proactive identification and resolution of such trade offs this paper reports on case based theory building research involving three cases from the uk and usa used in developing a conceptual model with associated tools in support of such a process

inventory performance under pack size constraints and spatially correlated demand abstract motivated by a problem facing a large retailer we consider the impact of pack size on the performance of a periodic review inventory system in the presence of spatial i e between retailers correlation of demand which we model using an equicorrelated multivariate poisson distribution employing simulation we utilise a full factorial experiment to provide support for decisions on product and supplier selection and whether or not packs should be split during distribution we consider variables such as pack size correlation and the number of branches and discuss how they and their interactions impact performance metrics such as inventory and shortage levels and the bullwhip effect

an empirically simulated investigation of the impact of demand forecasting on the bullwhip effect evidence from u s auto industry this study empirically examines the impacts of three major aspects of demand forecasting on the magnitude of the bullwhip effect three research questions are addressed to investigate the association between 1 forecast accuracy 2 aggregate forecasting and 3 responsive forecasting and the bullwhip effect using forecasted demand generated from popular time series forecasting models and real life demand data the study investigates the relationship between the forecasted results and the consequential bullwhip effect the findings show that the forecasting methods used lead to the variation of the bullwhip effect moreover the lead time reduction and the stable demand forecast are beneficial to reduce the bullwhip effect however our empirical results differ from previous findings in two ways i improving forecast accuracy does not necessarily reduce the bullwhip effect and ii aggregate forecasting does not always reduce the bullwhip effect

demand fluctuation and chaotic behaviour by interaction between customers and suppliers this paper presents an investigation on simulation of interaction between customers and suppliers in a three tier supply chain system in the simulation customers respond to the price discount offer made by the supplier and the supplier makes adjusts the price according to stock held the simulation shows that the behaviour of such interaction exhibits deterministic chaos it is found that the attractors of the model move with the environment and the initial states thus the bifurcating points in such a system are unable to provide a guideline in system design to avoid chaos

a novel time varying bullwhip effect metric an application to promotional sales abstract bullwhip effect is a problem of paramount importance that reduces competitiveness of supply chains around the world a significant effort is being devoted by both practitioners and academics to understand its causes and to reduce its pernicious consequences nevertheless limited research has been carried out to analyse potential metrics to measure it that typically are summarized in the coefficient of variation ratio of different echelons demand this work proposes a new metric based on a time varying extension of the aforementioned bullwhip effect metric by employing recursive estimation algorithms expressed in the state space framework to provide at each single time period a real time bullwhip effect estimate in order to illustrate the results a case study based on a serially linked supply chain of two echelons from the chemical industry is analysed particularly this metric is employed to analyse the effect of promotional campaigns on the bullwhip effect on a real time fashion the results show that effectively the bullwhip effect is not constant along time but interestingly it is reduced during the promotional periods and it is bigger before and after the promotion takes place

rogue seasonality detection in supply chains rogue seasonality or unintended cyclic variability in order and other supply chain variables is an endogenous disturbance generated by a company s internal processes such as inventory and production control systems the ability to automatically detect diagnose and discriminate rogue seasonality from exogenous disturbances is of prime importance to decision makers this paper compares the effectiveness of alternative time series techniques based on fourier and discrete wavelet transforms autocorrelation and cross correlation functions and autoregressive model in detecting rogue seasonality rogue seasonalities of various intensities were generated using different simulation designs and demand patterns to evaluate each of these techniques an index for rogue seasonality based on the clustering profile of the supply chain variables was defined and used in the evaluation the fourier transform technique was found to be the most effective for rogue seasonality detection which was also subsequently validated using data from a steel supply network

quantifying the bullwhip effect using two echelon data a cross industry empirical investigation the bullwhip effect denotes the phenomenon whereby demand variability is amplified from a downstream site buyer to an upstream site supplier in the supply chain this paper contributes to the literature that empirically investigates the bullwhip effect by providing new evidence regarding its prevalence and magnitude in contrast to previous work we use a two echelon approach which allows us to observe variations at both the upstream and the downstream sites by drawing on a financial accounting standard regarding information disclosure about major customers we are able to link 5494 buyers and suppliers in the u s between 1976 and 2009 we merge this information with quarterly financial accounting data to form a sample of 14 933 buyer supplier dyad observations we correct for sample selection bias using propensity score matching and estimate the average bullwhip effect in our sample to be 1 90 i e 90 demand variability amplification between echelons a significant bullwhip effect is observed across industries mining manufacturing wholesale and retail and is supported by several robustness checks we investigate and discuss how these results can be generalized beyond our sample

price environment and security exploring multi modal motivation in voluntary residential peak demand response peak demand on electricity grids is a growing problem that increases costs and risks to supply security residential sector loads often contribute significantly to seasonal and daily peak demand demand response projects aim to manage peak demand by applying price signals and automated load shedding technologies this research investigates voluntary load shedding in response to information about the security of supply the emission profile and the cost of meeting critical peak demand in the customers network customer willingness to change behaviour in response to this information was explored through mail back survey the diversified demand modelling method was used along with energy audit data to estimate the potential peak load reduction resulting from the voluntary demand response a case study was conducted in a suburb of christchurch new zealand where electricity is the main source for water and space heating on this network all water heating cylinders have ripple control technology and about 50 of the households subscribe to differential day night pricing plan the survey results show that the sensitivity to supply security is on par with price with the emission sensitivity being slightly weaker the modelling results show potential 10 reduction in critical peak load for aggregate voluntary demand response

on bullwhip in supply chains historical review present practice and expected future impact abstract demand amplification or bullwhip as it is now called is not a new phenomenon since evidence of its existence has been recorded at least as far back as the start of the 20th century and is well known to economists yet industry worldwide still has to cope with bullwhip measured not just in terms of the 2 1 amplification which is frequently quoted but sometimes it is as high as 20 1 from end to end in the supply chain this can be very costly in terms of capacity on costs and stock out costs on the upswing and stockholding and obsolescence costs on the downswing in this paper we have identified 10 published causes of bullwhip all of which are capable of elimination by re engineering the supply chain we offer evidence on the present health of a family of supply chains and pinpoint much good practice this is in anticipation that such excellence will become normative in the near future as the learning experience gathers momentum and provided that human factors are properly addressed

geographical and environmental perspectives for the sustainable development of renewable energy in urbanizing china with rapid urbanization and industrialization china has become both the largest energy consumer and co2 emitting country in the world as a clean and low carbon energy source renewable energy is a good choice to substitute for the exhausted fossil energy the chinese central and local governments have made a series of policies and optimistic plans to promote a rapid development of renewable energies china s renewable energy development has become a key to the sustainable development of socioeconomic system unlike most of the current studies which mainly identified the challenges regarding policies and technologies around renewable energy or performed specific analyses for a certain kind of renewable energy this paper summarizes the spatial disparity and consistency among the major renewable energies coal resources energy consumption and its major influencing factors in china and reviews the positive and negative environmental impacts of major renewable energies based on the geographical and environmental perspectives this paper recommends that the chinese government constructs the national energy production bases according to the resource distribution integrates different energies on the basis of their natural features and spatial consistency adjusts the overall layout of socio economic development consistent with renewable energies and promotes a moderate renewable energy development to maximize the environmental benefits c 2013 elsevier ltd all rights reserved

a pragmatic approach to the design of bullwhip controllers it is well known that forecasting mechanisms can greatly increase bullwhip demand variance amplification of orders as processed by both human and algorithmic decision makers this paper is concerned with the application of the well established apiobpcs decision support system a variant of the order up to rule in such circumstances it has two feedback controls based on the inventory and the orders in pipeline respectively with gains set equal according to the deziel eilon rule there is one feed forward control based on exponential forecasting although this is not a restriction on the application of this system we consider the pragmatic role of apiobpcs in the situation where the echelon decision maker may be handling a wide range of sku s in a non altruistic environment where upmarket information may either be withheld or simply unavailable under such circumstances it has been established via site based studies that the decision makers output the orders reflect a wide range of strategies or maybe ignorance three strategies may be regarded as appropriate i e pass orders along demand smoothing and level scheduling depending on context apiobpcs can be adapted to each of these modus operandi in the first case with the added capability of smoothing the sharp edges with a modicum of inventory variation and in the last case with the advantage of built in trend detection players in non altruistic supply chains must be able to cope with added uncertainties due to lead time variations we show that apiobpcs may be well matched to such situations and is hence copable as well as capable the paper includes recommended parameter settings according to desired decision making policies

a survey of china s low carbon application practice opportunity goes with challenge abstract the steady and maintainable energy supply for human development provides the strong motivation which is necessary to every country in the whole world the high strength carbon emissions has brought great harm to the earth since industrialization before hundreds of years and the global warming and extreme weather cause humans to develop low carbon economy low carbon economy has become a consensus of the entire human race no matter developed countries or developing countries which is the combination of the lifestyle changing and production structure basic changing and technical innovation it is well known that china is the largest developing country in the world with the rapid industrialization of country energy demand of chinese society is increasing in an incredible speed china has become the second largest energy consumer and the first carbon emissions country at present furthermore chinese energy structure and production methods are very inappropriate which cannot guarantee the sustainable development of china in future and therefore actively developing low carbon economy is the only road to realize china s economic development mode change and sustainable development which is supported by central government and local governments low carbon economy for china is not only an opportunity but also a great challenge firstly this paper discusses the current situation of energy supply and energy structure in china secondly current situation of units energy consumption in china is discussed thirdly some application practices of low carbon are described such as low carbon traffic low carbon city and low carbon village then the policies and law of china central government and local governments are described in the following paragraphs at the end the developmental prospect of low carbon economy in future china and the development barriers and recommendations are introduced respectively