on the integration of production and financial hedging decisions in global markets we study the integrated operational and financial hedging decisions faced by a global firm who sells to both home and foreign markets production occurs either at a single facility located in one of the markets or at two facilities one in each market the company has to invest in capacity before the selling season starts when the demand in both markets and the currency exchange rate are uncertain the currency exchange rate risk can be hedged by delaying allocation of the capacity to specific markets until both the currency and demand uncertainties are resolved and or by buying financial option contracts on the currency exchange rate when capacity commitment is made a mean variance utility function is used to model the firm s risk aversion in decision making we derive the joint optimal capacity and financial option decision and analyze the impact of the delayed allocation option and the financial options on capacity commitment and the firm s performance we show that the firm s financial hedging strategy ties closely to and can have both quantitative and qualitative impact on the firm s operational strategy the use or lack of use of financial hedges can go beyond affecting the magnitude of capacity levels by altering global supply chain structural choices such as the desired location and number of production facilities to be employed to meet global demand

note on managing multi echelon multi item channels with trade allowances under credit period abstract in the recently published paper tsao 2010 managing multi echelon multi item channels with trade allowances under credit period international journal of production economics 127 226 237 a supplier retailer inventory system with multiple items is studied where the supplier provides an interest free credit period for the retailer to compensate him for making promotional efforts to stimulate the demand for each item however as shown in this note there exist some nontrivial flaws in tsao s paper we identify and correct these flaws and develop efficient algorithms to derive the optimal solutions

dual sourcing of a newsvendor with exponential utility of profit abstract dual sourcing strategies supplement inflexible low cost country sourcing with quick response manufacturing due to short product life cycles combined with uncertain demand dual sourcing strategies are very common in several industries in particular in the sporting goods or fashion industries even though scholars have given some attention to the analysis of dual sourcing strategies the importance of the decision maker s risk preferences has not been covered yet in this paper we analyse dual sourcing strategies using an extended single product newsvendor model with two order points different risk preferences will be modelled using an exponential utility function within realistic parameter ranges the optimal order quantities can only be numerically computed the findings of this paper show that dual sourcing strategies are always preferable to an exclusive offshore approach as long as the onshore ordering costs are smaller than the selling price of the considered product the more risk averse the decision maker the smaller the offshore order quantity will be

energy efficiency and sustainable growth in industrial sectors in european union countries a nonlinear ardl approach abstract it can be said that economic growth providing it ensures a clean and safe environment is one of the main objectives of many countries with this in mind an important question needs to be asked what is the relationship between energy efficiency and economic growth this can only be answered through an empirical analysis by carrying out such an analysis using the energy efficiency of the industrial sector for 11 european union countries for a time span from 1997 to 2015 it should be possible to understand if the energy efficiency measures and investments being made are driving economies towards greater energy efficiency and sustainable growth this paper uses a nonlinear ardl model which allows short and long run relationships to be analysed for the ascending and descending movements of variables the results indicate that investment is increasing energy efficiency while at the same time reducing greenhouse gas emissions economic growth is driving economies to greater energy efficiency the same result is found in the industrial energy price index to verify robustness the environmental kuznets curve was estimated using gross domestic product per capita and as an alternative the industrial production index to ensure increased energy efficiency along with sustainable growth policymakers must adapt their policies and devise new ones to both incentivise investment and control energy pricing alternative ways of electricity generation such as renewable sources could allow the economy to grow in a more sustainable way such mechanisms would let policymakers develop policies for greener and more sustainable growth while at the same time encouraging the efficient use of energy

a note on lead time reduction strategies in a single vendor single buyer integrated inventory model with lot size dependent lead times and stochastic demand glock 2012 lead time reduction strategies in a single vendor single buyer integrated inventory model with lot size dependent lead times and stochastic demand international journal of production economics 136 37 44 recently presented an integrated inventory model where the lead time can be reduced by crashing the setup and transportation time by increasing the production rate or by decreasing the lot size in this note we introduce a more realistic lead time crashing cost and propose a modified integrated inventory model by adding the transportation time as a decision variable and assuming that there are two different safety stocks furthermore we give some numerical examples to illustrate the advantages of the modified model

a note on integrated single vendor single buyer model with stochastic demand and variable lead time abstract ben daya and hariga 2004 integrated single vendor single buyer model with stochastic demand and variable lead time international journal of production economics 92 75 80 recently proposed the paper about integrated single vendor single buyer model with stochastic demand and variable lead time the lead time is proportional to the lot size produced by the vendor in addition to a fixed delay due to the transportation setup and nonproductive time the end customers accept backorders when the shortage occurs at the buyer side an order to the vendor is placed each time the inventory level reaches the reorder point in this note a modified model is proposed under a different assumption that there are two different reorder points and service levels

joint economic lot sizing problem for a three layer supply chain with stochastic demand abstract this paper considers the joint economic lot sizing problem jelp for multi layer supply chain with multi retailers and single manufacturer and supplier the paper extends the work of ben daya et al 2013 and relaxes the assumption of deterministic demand and constant holding and ordering costs the paper proposes modifying four computational intelligent algorithms to solve mixed integer problems and compares their performance for solving the problem at hand the paper further compares between adopting a centralized safety stock policy versus a decentralized policy results showed cuckoo search to outperform other tested algorithms and also favored adopting a centralized policy

the risk averse newsvendor problem under spectral risk measures a classification with extensions abstract we study the risk averse newsvendor problem by defining the objective function as a spectral risk measure we analyze the problem under different types of return formulations focusing on the impact of risk aversion and cost parameters on the optimal ordering decision we show that the monotonicity of the return function with respect to random demand determines the structural properties of the problem when the return function is monotone in demand realization optimal order quantity does not depend on the return margin but only on the overage and underage costs and it has a monotone relation to risk aversion however if return is non monotone in demand impact of risk aversion depends on the specific setting and it can also be non monotone additionally it is non increasing in the margin which leads to varying impact of selling price under distinct settings

a utility adjusted newsvendor model with stochastic demand abstract we develop a continuous time newsvendor model to determine the optimal inventory level for commodities in an established financial market unlike most models in literature the newsvendor is not necessarily risk neutral and chooses the order quantity that maximises the expected utility of the cash flow at the end of the period the newsvendor exploits the correlation between stochastic demand and the price of the commodities in order to manage risks by investing in a portfolio of financial instruments the decision problem therefore includes not only the determination of the optimal ordering policy but also at the same time the selection of a portfolio that maximises her utility further we demonstrate that our model compared to a myopic approach i e no hedging requires significantly lower levels of inventory buffer to mitigate demand uncertainty thus better utilising capital

lot sizing and lead time decisions in production inventory systems traditionally lot sizing decisions in inventory management trade off the cost of placing orders against the cost of holding inventory however when these lot sizes are to be produced in a finite capacity production inventory system the lot size has an important impact on the lead times which in turn determine inventory levels and costs in this paper we study the lot sizing decision in a production inventory setting where lead times are determined by a queueing model that is linked endogenously to the orders placed by the inventory model assuming a continuous review s s inventory policy we develop a procedure to obtain the distribution of lead times and the distribution of inventory levels when lead times are endogenously determined by the inventory model this procedure allows to determine the optimal inventory parameters within the class of s s policies that minimize the expected ordering and inventory related costs over time we numerically show that ignoring the endogeneity of lead times may lead to inappropriate lot sizing decisions and significantly higher costs this cost discrepancy is very outspoken if the lot size based on the economic order quantity deviates significantly from desirable production lot sizes in these cases the endogenous treatment of lead times is of particular importance

the energy efficiency situation in ghana abstract ghana s electricity sector has long been saddled with challenges regarding supply security and power quality the existing power plants are not able to attain full generation capacity due to fuel supply constraints as well as the uncertainty of rainfall and water inflows into the hydroelectric power plants there has been an imbalance between demand and supply in the country with a shortage of 25 of peak power reported in year 2014 2015 in dealing with the energy crises the focus of the country s energy sector has been on the installation of additional thermal power plants however capacity additions face a number of obstacles such as the requirement for high capital investments timely approvals to build new power plants and there has been increasing inflation problem therefore securing adequate supplies to meet rapidly growing demand remains a challenge at least in the short term coupled with this is the country s electrical appliance market which has been flooded with imports of used low efficiency appliances from overseas as the country achieves middle income status the number of households that can afford major household appliances is expected to increase with the prospect of many consumers buying inefficient appliances thereby unnecessarily burdening the national grid while energy efficiency ee is internationally recognised as a low cost readily available resource that could help improve electricity supply security its implementation in ghana has only recently been given serious attention this paper provides a review of energy efficiency initiatives undertaken by the regulating agencies responsible for energy issues it provides a comprehensive overview of the current energy efficiency status of three household appliances namely refrigerators air conditioners and lighting systems the review indicates that ee measures carried out especially in the replacement of incandescent lamp with compact fluorescent light cfl made significant savings that offset the national electricity peak demand by 200 240 mw

a single item continuous review inventory problem with space restriction abstract with today s high cost of land acquisition observed in most countries management can no longer afford large storage facilities to house their products for this reason one of the main concerns of inventory managers is to ensure that enough storage space is available upon the delivery of a product they therefore have to determine the least cost ordering policy so as to meet demand and taking into account the space limitation in this paper we investigate the problem of a single item continuous review inventory problem in the presence of a space restriction when the demand is stochastic through a sensitivity analysis study it is found that ordering cost storage capacity average demand per unit time and holding cost rate are the most influential problem parameters on the expected inventory costs it is also shown numerically that a simple solution based on economic order quantity is performing very well with an average and maximum cost penalty of 0 19 and 2 03 respectively

integrated single vendor single buyer model with stochastic demand and variable lead time abstract in this paper we consider the single vendor single buyer integrated production inventory problem we relax the assumption of deterministic demand and assume that the lead time is varying lineraly with the lot size the lead time is composed of a lot size dependent run time and constant delay times such as moving waiting and setup times a solution procedure is suggested for solving the proposed model and numerical examples are used to illustrate the benefit of integration a sensitivity analysis is also performed to explore the effect of key parameters on lot size reorder point and expected total cost

analysis of energy end use efficiency policy in spain abstract the implementation of saving measures and energy efficiency entails the need to evaluate achievements in terms of energy saving and spending this paper aims at analysing the effectiveness and economic efficiency of energy saving measures implemented in the energy savings and efficiency action plan 2008 2012 eap4 in spain for 2010 the lack of assessment related to energy savings achieved and public spending allocated by the eap4 justifies the need of this analysis the results show that the transport and building sectors seem to be the most important from the energy efficiency perspective although they did not reach the direct energy savings that were expected there is scope for reduction with the appropriate energy measures for the effectiveness indicator the best performance are achieved by public service agricultural and fisheries and building sectors while in terms of energy efficiency per monetary unit the best results are achieved by transport industry and agriculture sectors authors conclude that it is necessary that central regional and local administrations will get involved in order to get better estimates of the energy savings achieved and thus to affect the design of future energy efficiency measures at the lowest possible cost to the citizens

on sales effort and pricing decisions under alternative risk criteria abstract in the literature different risk criteria are proposed for risk averse decision making but it is often unclear which risk criteria should be used and what their differences may be this study investigates this problem when a risk averse make to order firm decides its pricing and sales effort two factors affecting demand we consider alternative risk criteria commonly used in the literature namely expected utility theory eut mean variance mv mean semideviation ms value at risk var conditional value at risk cvar and loss aversion la we find that all of these criteria lead to similar qualitative behaviors regarding how risk loss averse decisions deviate from risk neutral ones a particularly interesting result is that the form of demand randomness i e additive or multiplicative can completely reverse the effect of risk loss aversion in certain cases we also find that the risk aversion models i e eut mv ms var and cvar are essentially equivalent in inducing the same set of optimal solutions under adverse market states however loss aversion is a mild version of risk aversion in that the la model can only lead to a subset of the solutions generated by other models these results may not be valid for other applications such as the newsvendor pricing problem so we can conclude that the relationship between alternative risk criteria is case sensitive and should be evaluated more carefully

note comments on a quantity discount pricing model to increase vendor profits monahan monahan j p 1984 a quantity discount pricing model to increase vendor profits management sci june 720 726 adapted the quantity discount model of inventory theory to the problem of determining an optimal quantity discount schedule from a vendor s point of view and opened up an important direction of research however his one item one customer one vendor model is based on several implicit assumptions that must be judged unreasonable monahan must account for the vendor s inventory carrying charges and redefine his variable s2 it is shown that a rational vendor s manufacturing frequency would not be identical to the buyer s ordering frequency if the vendor s manufacturing setup costs are substantially larger than the buyer s ordering costs a numerical example presented in this note also questions the practical usefulness of monahan s model even after its theoretical inaccuracies axe corrected monahan s model may explain discounts that are a fraction of 1 of the price of an item but it fails to explain commonly observed magnitudes of quantity discounts such as 10 of the unit price

a heuristic solution technique to attain the minimal total cost bounds of transporting a homogeneous product with varying demands and supplies abstract transportation of a product from multi source to multi destination with minimal total transportation cost plays an important role in logistics and supply chain management researchers have given considerable attention in minimizing this cost with fixed supply and demand quantities however these quantities may vary within a certain range in a period due to the variation of the global economy so the concerned parties might be more interested in finding the lower and the upper bounds of the minimal total costs with varying supplies and demands within their respective ranges for proper decision making this type of transportation problem has received attention of only one researcher who formulated the problem and solved it by lingo we demonstrate that this method fails to obtain the correct upper bound solution always then we extend this model to include the inventory costs during transportation and at destinations as they are interrelated factors the number of choices of supplies and demands within their respective ranges increases enormously as the number of suppliers and buyers increases in such a situation although the lower bound solution can be obtained methodologically determination of the upper bound solution becomes an np hard problem here we carry out theoretical analyses on developing the lower and the upper bound heuristic solution techniques to the extended model a comparative study on solutions of small size numerical problems shows promising performance of the current upper bound technique another comparative study on results of numerical problems demonstrates the effect of inclusion of the inventory costs

a multi product continuous review inventory system with stochastic demand backorders and a budget constraint abstract common characteristics of inventory systems include uncertain demand and restrictions such as budgetary or storage space constraints several authors have examined budget constrained multi item stochastic inventory systems controlled by continuous review policies without considering marginal shortage costs existing models assume that purchasing costs are paid at the time an order is placed which is not always the case since in some systems purchasing costs are paid when orders arrive in the latter case the maximum investment in inventory is random since the inventory level when an order arrives is a random variable hence payment of purchasing costs on delivery yields a stochastic budget constraint for inventory this paper models a multi item stochastic inventory system with backordered shortages when estimation of marginal backorder cost is available and payment is due upon order arrival the budget constraint can easily be converted into a storage constraint

integrated vendor buyer cooperative models with stochastic demand in controllable lead time abstract this article presents the single vendor single buyer integrated production inventory models we relax the assumption that lead time demand x is deterministic and assume that it is stochastic also we assume that shortage during the lead time is permitted and lead time can be reduced at an added cost two models are considered here in the first model the demand of lead time follows a normal distribution and in the second model it is distribution free for both cases we develop effective iterative procedures for finding the optimal policy and numerical examples are used to illustrate the benefits of integration

improving electricity supply security in ghana the potential of renewable energy for decades ghana s economy has been fuelled by abundant inexpensive hydropower as a developing economy ghana s electricity demand has long been relatively low though rising in recent times due to increasing economic growth urbanization and industrial activities however the rapid demand growth as well as periodic hydrological shocks leaves the country increasingly reliant on expensive oil and gas based generation power plants with a resultant drain on the national economy the main electricity generation company the volta river authority is not able to generate enough electricity for all the demand sectors the electricity supply demand margins the difference between peak demand and available supply of the country fall short of the recommended engineering practice and thus presents a high supply security risk the country has been experiencing an increase in the frequency of power cuts over the last ten years it is clear that ghana will have to expand and diversify its generation capacity in order to improve supply security this paper provides a review of the assessed potential renewable energy resources their current exploitation status and their potential contribution to the electricity supply of the country the paper also presents the barriers to their utilization and the existing policy and regulatory instruments to overcome those barriers plus the current and expected future impacts of these instruments the results show that ghana has several res such as wind solar pv mini hydro and modern biomass that can be exploited for electricity production while their exploitation for electricity generation is currently very low providing just 0 13 of the country s generation the review shows a great potential for res generation to increase substantially over the next decade looking at the government commitment and legal frameworks that are being put in place

risk aversion in inventory management traditional inventory models focus on risk neutral decision makers i e characterizing replenishment strategies that maximize expected total profit or equivalently minimize expected total cost over a planning horizon in this paper we propose a framework for incorporating risk aversion in multiperiod inventory models as well as multiperiod models that coordinate inventory and pricing strategies we show that the structure of the optimal policy for a decision maker with exponential utility functions is almost identical to the structure of the optimal risk neutral inventory and pricing policies these structural results are extended to models in which the decision maker has access to a partially complete financial market and can hedge its operational risk through trading financial securities computational results demonstrate that the optimal policy is relatively insensitive to small changes in the decision maker s level of risk aversion

optimal ordering quantities for multi products with stochastic demand return cvar model abstract multi product ordering problem with stochastic demand is often optimized by the expected cost reduction or the expected profit improvement in most of previous works moreover risk preference of decision maker is often ignored evidently this approach is impracticable when the corresponding volatility is larger based on the outstanding characteristics of conditional value at risk cvar as a risk measure the paper proposes an optimal order model for multi product with cvar constraints also the model is finally formulated as a linear programming problem the model is simulated for the case of a newsvendor to analyze to what degree it succeeds the solution in fact is bound consistent fully with the decision maker s intuition on return risk decision making finally results of return cvar model and the classical model are compared and shows that return cvar model is more flexible than the classical model

improved quality setup cost reduction and variable backorder costs in an imperfect production process abstract this paper illustrates the relationship between quality improvement reorder point and lead time as affected by backorder rate in an imperfect production process to reduce the total system cost by optimizing the setup cost lot size lead time reorder point and process quality parameter simultaneously we first consider that the lead time demand follows a normal distribution then we apply the distribution free approach for the lead time demand we prove two lemmas which are used to find optimal solutions for the basic and distribution free models we compare our models with the existing models using numerical examples and show that significant savings over the existing models can be achieved

an optimal vendor buyer cooperative policy under generalized lead time distribution with penalty cost for delivery lateness abstract this paper presents an integrated inventory model for a single vendor and single buyer where lead time is a stochastic variable with general distribution function the vendor delivers goods at a fixed lot size to the buyer who has a constant demand rate storage is permitted on both parties but a penalty cost is assessed when the vendor delivers the shipment late beyond a threshold time the problem is formulated as a nonlinear cost model which needs to be minimized to arrive at an optimal policy for reorder point order quantity and number of shipments from the vendor to buyer to cooperatively operate the joint contract the solution procedure involves both closed form solution and iterative search procedure for this multi dimensional problem numerical examples are presented for uniform exponential and normally distributed lead time s to demonstrate the solution methodology as well as a precursor test for special cases the model presented here are applicable for numerous two stage supply chain systems including retail businesses assembly and production houses where two parties of the supply chain are tied to their common goal of achieving minimum total cost of inventory operation

sequential correlated equilibria in stopping games in many situations such as trade in stock exchanges agents have many opportunities to act within a short interval of time the agents in such situations can often coordinate their actions in advance but coordination during the game consumes too much time an equilibrium in such situations has to be sequential in order to handle mistakes made by players in this paper we present a new solution concept for infinite horizon dynamic games which is appropriate for such situations a sequential normal form correlated approximate equilibrium under additional assumptions we show that every such game admits this kind of equilibrium

a one vendor multi buyer integrated inventory model abstract we consider a one vendor multi buyer integrated inventory model the vendor seeks to minimize his total annual cost subject to the maximum costs which buyers are prepared to incur in order to implement this model the vendor only needs to know buyer s annual demand and previous order frequency which can be inferred from buyer s past ordering behavior we find the optimal solution for the one vendor one buyer case and present a heuristic approach for the one vendor multi buyer case

inventory control with an exponential utility criterion a base stock policy is shown to be optimal when a dynamic version of the news vendor model is optimized with respect to an exponential utility criterion

the newsstand problem a capacitated multiple product single period inventory problem abstract practically all of the many earlier papers on the newsboy problem consider a single newsboy product with no capacity constraint this paper presents formulations and solution procedures for handling multiple newsboy type products under two cases a one resource capacity constraint and b multiple resource constraints for case a we present a necessary extension to the classical hadley whitin result for handling general demand distributions for case b we present a solution procedure that can efficiently handle the common situation where a very large number of products are involved

impact of risk aversion on optimal decisions in supply contracts abstract we introduce the concept of conditional value at risk as the evaluation criterion in a supply contract model we first derive the manufacturer s optimal decisions and then analyze the impact of risk aversion on the manufacturer s decisions we follow by conducting numerical experiments to observe how the manufacturer s risk attitude affects his decisions we obtain results that characterize the explicit relationship between the manufacturer s risk attitude and his optimal decisions we also show the dependence of the decision variables on the price and cost parameters which is seldom given in the literature

inventory control in a lost sales setting with information about supply lead times abstract supply chain collaboration using advancements in information technology is on the rise and this includes sharing of information between suppliers and buyers in this paper we study the value of information about the development of supply lead times from a buyer s perspective we consider a periodically reviewed single item inventory system in a lost sales setting where at most one order can be outstanding at a time we compare the performance of an inventory model assuming informed lead times to a model assuming uninformed independent and identically distributed lead times we employ the dynamic programming approach to find the best state dependent ordering policy to minimize the expected average total cost per time unit our numerical results show that acquiring information about the development of supply lead times is of value in general the best policy suggested by the model assuming informed lead times causes lower average cost than the model assuming uninformed lead times

equilibrium pricing and lead time decisions in a competitive industry pricing and lead time are two crucial decisions to a success in today s competitive markets this paper examines the equilibrium pricing and lead time decisions in a duopoly industry consisting of two large and several smaller firms with competition we solve the sufficient karush kuhn tucker kkt optimality conditions for the nash equilibrium solution we characterize the existence and uniqueness of the nash equilibrium solution of pricing and lead time decisions for both homogenous and heterogeneous firms our case study provides important managerial insights about firms behavior under price and lead time competition in a semiconductor manufacturing industry

reordering strategies for a newsboy type product abstract this paper considers the very common situation in which a single period newsboy type product may be ordered or produced twice during a season period we show that the explicit consideration of this reorder opportunity makes the newsboy problem very much richer the specific version considered in this paper allows a reorder during mid season after the early season demand has been observed and this reorder arrives after a given lead time the demand distributions during the various portions of the season may have very general distribution forms also the late season and early season demands may be dependent solution procedures are developed to find the best way to exploit this reorder opportunity and our numerical solutions indicate that this reorder opportunity can improve profits considerably as long as the product s profit margin is not very high other real world variations of this two order newsboy problem are briefly discussed

the joint economic lot size problem a review abstract this article reviews lot size models which focus on coordinated inventory replenishment decisions between buyer and vendor and their impact on the performance of the supply chain these so called joint economic lot size jels models determine order production and shipment quantities from the perspective of the supply chain with the objective of minimizing total system costs this paper first describes the problem studied introduces the methodology of the review and presents a descriptive analysis of the selected papers subsequently papers are categorized and analyzed with respect to their contribution to the coordination of different echelons in the supply chain finally the review highlights gaps in the existing literature and suggests interesting areas for future research

a single vendor single manufacturer integrated inventory model with stochastic demand and variable production rate abstract this paper investigates an alternative way to react to demand uncertainty in an integrated inventory model namely the variation of the production rate that enables the manufacturer to reduce lead times and the corresponding demand uncertainty to investigate the impact of variable production rates on the supply chain this paper considers a single vendor single manufacturer integrated inventory model where the vendor ships finished products in multiples of full truckloads to the manufacturer the objective of the model is to coordinate both production and distribution of the product in such a way that the total costs of the supply chain are minimized a solution procedure is suggested and the behaviour of the model is analysed in numerical examples obviously the total supply chain cost is reduced when the manufacturer s production rate is included as a decision variable in the model these savings can generally benefit both the vendor and the manufacturer however in situations where coordinated decision making is initially not beneficial to the vendor the supply chain members can benefit from a revenue sharing contract that supports the sharing of the total savings the model proposed in the paper at hand supports both the determination of an optimal production rate as well as the distribution of coordination benefits among the supply chain members

optimal vendor investment for reducing defect rate in a vendor buyer integrated system with imperfect production process this paper investigates a single vendor single buyer integrated production inventory model with stochastic demand and imperfect production process it is assumed that there is an inspection activity on the part of the buyer with a fixed screening rate greater than the demand rate the vendor invests money in order to improve the production process quality and reduce the number of defectives the expected annual integrated total cost is derived under the n shipment policy and an iterative procedure is suggested to determine the optimal decisions the benefit of investment in reducing the defect rate is illustrated by way of numerical examples it is observed that the higher the defect rate the more beneficial the investment numerical studies further explore that an increased demand requires an increased investment to optimize the total cost

lead time reduction strategies in a single vendor single buyer integrated inventory model with lot size dependent lead times and stochastic demand this paper studies alternative methods for reducing lead time and their impact on the safety stock and the expected total costs of a q s continuous review inventory control system we focus on a single vendor single buyer integrated inventory model with stochastic demand and variable lot size dependent lead time and assume that lead time consists of production and setup and transportation time as a consequence lead time may be reduced by crashing setup and transportation time by increasing the production rate or by reducing the lot size we illustrate the benefits of reducing lead time in numerical examples and show that lead time reduction is especially beneficial in case of high demand uncertainty further our studies indicate that a mixture of setup time and production time reduction is appropriate to lower expected total costs

aggregate constrained inventory systems with independent multi product demand control practices and theoretical limitations in practice inventory managers are often confronted with a need to consider one or more aggregate constraints these aggregate constraints result from available workspace workforce maximum investment or target service level we consider independent multi item inventory problems with aggregate constraints and one of the following characteristics deterministic leadtime demand newsvendor basestock policy rq policy and ss policy we analyze some recent relevant references and investigate the considered versions of the problem the proposed model formulations and the algorithmic approaches finally we highlight the limitations from a practical viewpoint for these models and point out some possible direction for future improvements

environmental performance impacts of vendor buyer coordination abstract effective coordination is a hallmark of successful supply chain management without such coordination vendors and buyers will act independently to make decisions that optimize their own objectives e g maximize their respective profits or minimize their costs this non coordinated approach is unlikely to be optimal when one considers the supply chain as a whole most vendor buyer coordination research concentrates only on an objective of minimizing total system costs but with the increasing environmental awareness in business and the general public many organizations acknowledge that strategies and practices which incorporate environmental considerations are essential to acquire a competitive advantage the objectives of this research are concerned not only with the economic impact of vendor buyer coordination on the organizations involved but also with the wider effects on society such as the effects of pollution on the environment this research demonstrates how to effectively incorporate environmental issues into vendor buyer coordination first we study the impacts of cost minimizing vendor buyer coordination models on environmental performance when compared with independent non coordinated optimization second we develop a single vendor multi buyer coordination model that includes both costs and environmental performance measures in its objective function a numerical example and a real case study show how both the total system cost and the environmental performance can be simultaneously improved

investing in reduced setups in the eoq model this paper is motivated by the observation that the japanese have devoted much time and energy to decreasing setup costs in their manufacturing processes and that there has been little in the way of a formal framework available to use to think about such efforts the object of this paper is to begin to provide such a framework the framework developed identifies only one aspect of the advantages of reducing setups namely reduced inventory related operating costs the other advantages such as improved quality control flexibility and increased effective capacity are not accounted for in this paper nevertheless substantial reductions in setups may be warranted based solely on the benefits identified in this paper the approach taken here introduces an investment cost associated with changing the current setup level and adds a per unit time amortization of this cost to the other costs identified in the standard eoq model the general problem becomes that of minimizing the sum of a convex and a concave function in two special cases the minimization can be carried out explicitly in one of these cases numerous interpretations of the results are made including comparisons of japanese and american practices for example holding other parameters constant there is a critical sales level such that investment is made in reducing setups if and only if the sales rate is above that level when such investment is made the optimal lot size is independent of the sales rate the paper also addresses the joint selection of the setup cost and the sales rate selection of the sales rate is seen as incorporating explicit production and holding costs into the classical monopolist s pricing problem an explicit solution is obtained for the model postulated

product variety arising from hedging in the fashion supply chains consider a well defined fashion apparel category where the variants are distinguished by style and colour and are subject to two equally likely states of the world state1 when some variants become popular and others unpopular and state2 when the reverse takes place we analyse the optimal portfolio and variety arising from hedging against uncertainty triggered by the states by integrating the markowitz and the newsboy models while carefully considering demand correlations we show that due to the complex structure of the uncertainty building hedging portfolios with competing items is necessary for optimality we also show how mis specifying the distributions can lead to very bad trade offs between risk and expected profit caused by a lack of proper hedging

an optimal solution technique to the single vendor multi buyer integrated inventory supply chain by incorporating some realistic factors abstract this paper develops two generalized integrated inventory models to deliver a single product from a vendor to multiple buyers to minimize the total cost of set up ordering inventory holding and transportation the production flow is synchronized by transferring the lot with equal and or unequal either all are equal or all are unequal or a combination of equal and unequal sized batches sub lots each of which incurs a transportation cost for easy implementation of the models we relax some unrealistic assumptions in the existing models such as unlimited capacities of the transport equipment and buyers storage insignificant set up and transportation times unlimited lead time and batch sizes a common optimal solution technique to the models is derived and their performances are analyzed potential significances of the solution method are highlighted with solutions of some numerical problems the importance of the relaxed factors and limitation of the models are discussed

the component procurement problem for the loss averse manufacturer with spot purchase abstract this paper studies the purchasing behaviour of a loss averse engineer to order manufacturer who purchases a key component for his final product from a supplier under a single wholesale price contract with spot purchase opportunities where both the product demand and the component spot price are uncertain through newsvendor type of models we analyze several key issues including the effects of the manufacturer s loss aversion and the effects of demand and spot price uncertainties on the manufacturer s decision behaviour we find that the purchasing behaviour of the loss averse manufacturer differs from those of the risk neutral and risk averse ones specifically we identify some sufficient conditions under which the loss averse manufacturer may purchase a larger order quantity in advance when demand becomes more uncertain or when the price becomes more uncertain we also discuss the two wholesale price contract and show that fixing the emergency supply price may lead to a smaller order quantity

the newsvendor problem review and directions for future research in this paper we review the contributions to date for analyzing the newsvendor problem our focus is on examining the specific extensions for analyzing this problem in the context of modeling customer demand supplier costs and the buyer risk profile more specifically we analyze the impact of market price marketing effort and stocking quantity on customer demand how supplier prices can serve as a coordination mechanism in a supply chain setting integrating alternative supplier pricing policies within the newsvendor framework and how the buyer s risk profile moderates the newsvendor order quantity decision for each of these areas we summarize the current literature and develop extensions finally we also propose directions for future research

robust multi item newsboy models with a budget constraint abstract in this paper we present robust newsboy models with uncertain demand the traditional approach to describing uncertainty is by means of probability density functions in this paper we present an alternative approach using deterministic optimization models we describe uncertainty using two types of demand scenarios namely interval and discrete scenarios for interval demand scenarios we only require a lower and an upper bound for the uncertain demand of each item while for discrete demand scenarios we require a set of likely demand outcomes for each item using the above scenarios to describe demand uncertainty we develop several minimax regret formulations for the multi item newsboy problem with a budget constraint for the problems involving interval demand scenarios we develop linear time optimal algorithms we show that the corresponding models with discrete demand scenarios are np hard and that they are solvable by dynamic programming finally we extend the above results to the case of mixed scenarios where the demand of some of the items is described by interval scenarios and the demand of the remaining items is described by discrete scenarios

newsvendor model with random supply and financial hedging utility based approach abstract this paper takes a utility based approach to the single period and single item newsvendor model unlike most models in the literature the newsvendor is not necessarily risk neutral and chooses the order quantity that maximizes the expected utility of the cash flow at the end of the period we suppose that there is uncertainty in demand as well as supply furthermore random demand and supply may be correlated with the financial markets the newsvendor exploits this correlation and manages his risks by investing in a portfolio of financial instruments the decision problem therefore includes not only the determination of the optimal ordering policy but also the selection of the optimal portfolio at the same time we first use a minimum variance approach to select the portfolio the analysis results in some interesting and explicit characterizations on the structure of the optimal policy we also present numerical examples to illustrate the effects of the parameters on the optimal order quantity and the importance of financial hedging on risk reduction

a multi product risk averse newsvendor with exponential utility function abstract we consider a multi product newsvendor using an exponential utility function we first establish a few basic properties for the newsvendor regarding the convexity of the model and monotonicity of the impact of risk aversion on the solution when the product demands are independent and the ratio of the degree of risk aversion to the number of products is sufficiently small we obtain closed form approximations of the optimal order quantities the approximations are as easy to compute as the risk neutral solution we prove that when this ratio approaches zero the risk averse solution converges to the corresponding risk neutral solution when the product demands are positively negatively correlated we show that risk aversion leads to lower higher optimal order quantities than the solution with independent demands using a numerical study we examine convergence rates of the approximations and thoroughly study the interplay of demand correlation and risk aversion the numerical study confirms our analytical results and further shows that an increased risk aversion does not always lead to lower order quantities when demands are strongly negatively correlated

erratum to lead time reduction strategies in a single vendor single buyer integrated inventory model with lot size dependent lead times and stochastic demand international journal of production economics 136 2012 37 44

multi product newsvendor problem with value at risk considerations abstract we consider the single period stochastic inventory newsvendor problem with downside risk constraints the aim in the classical newsvendor problem is maximizing the expected profit this formulation does not take into account the risk of earning less than a desired target profit or losing more than an acceptable level due to the randomness of demand we utilize value at risk var as the risk measure in a newsvendor framework and investigate the multi product newsvendor problem under a var constraint to this end we first derive the exact distribution function for the two product newsvendor problem and develop an approximation method for the profit distribution of the n product case n 2 a mathematical programming approach is used to determine the solution of the newsvendor problem with a var constraint this approach allows us to handle a wide range of cases including the correlated demand case that yields new results and insights the accuracy of the approximation method and the effects of the system parameters on the solution are investigated numerically

operational flexibility and financial hedging complements or substitutes we consider a firm that invests in capacity under demand uncertainty and thus faces two related but distinct types of risk mismatch between capacity and demand and profit variability whereas mismatch risk can be mitigated with greater operational flexibility profit variability can be reduced through financial hedging we show that the relationship between these two risk mitigating strategies depends on the type of flexibility product flexibility and financial hedging tend to be complements substitutes i e product flexibility tends to increase decrease the value of financial hedging and vice versa financial hedging tends to increase decrease the value of product flexibility when product demands are positively negatively correlated in contrast to product flexibility postponement flexibility is a substitute to financial hedging as intuitively expected although our analytical results assume perfect flexibility and perfect hedging and rely on a linear approximation of the value of hedging we validate their robustness in an extensive numerical study

risk sensitive dynamic market share attraction games we present partial results showing that risk sensitive oligopolists would spend less on advertising than would their risk neutral counterparts the model is an infinite horizon stochastic game in which each firm s goodwill is a random function of both its own and its competitors current and past advertising expenditures single period firm profits have a market share attraction form each firm seeks to maximize its expected exponential utility of the sum of discounted profits we analyze the impact that risk sensitivity and other parameters have on equilibrium advertising strategies by exploiting the special structure of the stochastic game model journal of economic literatureclassification number c73

optimal market making with risk aversion market makers have the obligation to trade any given amount of assets at quoted bid or ask prices and their inventories are exposed to the potential loss when the market price moves in an undesirable direction one approach to reduce the risk brought by price uncertainty is to adjust the inventory at the price of losing potential spread gain using stochastic dynamic programming we show that a threshold inventory control policy is optimal with respect to an exponential utility criterion and a mean variance trade off model symmetric and monotone properties of the threshold levels are also established