perishable inventory theory a review this paper reviews the relevant literature on the problem of determining suitable ordering policies for both fixed life perishable inventory and inventory subject to continuous exponential decay we consider both deterministic and stochastic demand for single and multiple products both optimal and sub optimal order policies are discussed in addition a brief review of the application of these models to blood bank management is included the review concludes with a discussion of some of the interesting open research questions in the area

dare to care shipment consolidation reduces not only costs but also environmental damage abstract companies interested in greening their supply chains quickly realize that carbon and energy waste represents an expense and thus minimizing this expense not only brings in truckloads of money but also helps save the environment this paper demonstrates that shipment consolidation a powerful logistics strategy that combines two or more small shipments into an aggregate load to be dispatched on the same vehicle can help mitigate carbon and energy waste specifically a discrete time based shipment consolidation dtb scl policy and a new method to calculate co2 emissions associated with the dispatch of a vehicle are introduced in addition an optimization model with the objective of maximizing combined economic and environmental savings is developed in this study it is shown that among other benefits the higher use of transportation capacity decreases environmental damage one goal of the dtb scl policy the mechanics of the mathematical models are illustrated by numerical examples and sensitivity analyses are conducted to provide managerial insights that might help companies come to better decisions that are environmentally responsible

a model for supply planning under lead time uncertainty the paper is focused on the search of the optimal values of the planned lead times for the mrp method under lead time uncertainty the problem is to find the planned lead times which minimize the expected backlogging and holding costs the aim of the paper is to give a mathematical formulation of this single level multi item dynamic multi period planning problem for the case where lead time does not depend on the lot size and demand level is constant an auxiliary markov model is proposed some new formulations of optimal control policies are obtained using this markov model

an optimization approach for managing fresh food quality throughout the supply chain one of the most challenging tasks in today s food industry is controlling the product quality throughout the food supply chain in this paper we integrate food quality in decision making on production and distribution in a food supply chain we provide a methodology to model food quality degradation in such a way that it can be integrated in a mixed integer linear programming model used for production and distribution planning the resulting model is applied in an illustrative case study and can be used to design and operate food distribution systems using both food quality and cost criteria

an milp approximation for ordering perishable products with non stationary demand and service level constraints abstract we study the practical production planning problem of a food producer facing a non stationary erratic demand for a perishable product with a fixed life time in meeting the uncertain demand the food producer uses a fifo issuing policy the food producer aims at meeting a certain service level at lowest cost every production run a setup cost is incurred moreover the producer has to deal with unit production cost unit holding cost and unit cost of waste the production plan for a finite time horizon specifies in which periods to produce and how much we formulate this single item single echelon production planning problem as a stochastic programming model with a chance constraint we show that an approximate solution can be provided by an milp model the generated plan simultaneously specifies the periods to produce and the corresponding order up to levels the order up to level for each period is corrected for the expected waste by explicitly considering for every period the expected age distribution of the products in stock the model assumes zero lead time and backlogging of shortages the viability of the approach is illustrated by numerical experiments simulation shows that in 96 4 of the periods the service level requirements are met with an error tolerance of 1

modeling recreation site choice do hypothetical choices reflect actual behavior we examine the ability of revealed preference rp site specific stated preference sp transferred sp and joint rp sp models to predict aggregate and individual recreation site choice in a holdout sample for two statistical comparisons the rp model provided the most accurate predictions of individual choices however the transferred sp model applied directly or estimated jointly with the rp data performed best in three aggregate and one individual prediction test these findings suggest that data from well designed and conducted sp surveys from one site can be combined with site specific rp data from another site to generate improved models of recreation site choice an objective of many economic studies is to construct models of choice behavior these models form the basis for welfare mea surement the models can also be used to make predictions of choice behavior that can inform policy makers of the proba ble results of changes in economic fac tors resource

operations research for green logistics an overview of aspects issues contributions and challenges the worldwide economic growth of the last century has given rise to a vast consumption of goods while globalization has led to large streams of goods all over the world the production transportation storage and consumption of all these goods however have created large environmental problems today global warming created by large scale emissions of greenhouse gasses is a top environmental concern governments action groups and companies are asking for measures to counter this threat operations research has a long tradition in improving operations and especially in reducing costs in this paper we present a review that highlights the contribution of operations research to green logistics which involves the integration of environmental aspects in logistics we give a sketch of the present and possible developments focussing on design planning and control in a supply chain for transportation inventory of products and facility decisions while doing this we also indicate several areas where environmental aspects could be included in or models for logistics

reducing emissions in transportation and inventory management r q policy with considerations of carbon reduction abstract in this study we examine three approaches on the effects of controlling carbon emissions in transportation and inventory management a business as usual scenario model bausm which delineates how carbon footprints from inventory storage and related transportation are captured is firstly developed as the benchmark model based on bausm we then develop three models with different carbon reduction approaches the first one is constructed by adding a constraint to represent the percentage target of emission reduction the second one integrates carbon taxes or cap and trade scheme into inventory management and the last one takes both reduction target and carbon offset opportunities into account our work provides new analytical models which integrate cost and emissions in transportation and storage under the framework of continuous inventory review r q policy for stochastic demand optimization algorithms are developed for solving models and related properties are investigated to examine the effects of carbon reduction and associated costs of three models the policy implications of the models are examined and discussed to provide insights for reference of the practitioners and the policy makers

how important is pro social behaviour in the delivery of public services a number of papers have suggested that pro social behaviour in the workplace may be sensitive to the institutional environment but there is little empirical research that attempts to test this directly using data on worker behaviour this is the aim of this paper we show that individuals in the non profit sector are significantly more likely to do unpaid overtime than those in the for profit sector however we find no evidence of adjustment along either the extensive or intensive margins when individuals change sectors the results of our analysis therefore point to selection and we find supporting evidence that individuals do self select on the basis of their propensity to donate labour

a heuristic for single warehouse multiretailer supply chains with all unit transportation cost discounts abstract in supply chain management research transportation costs if explicitly considered at all are frequently assumed to be linear these costs often have a more complex form such as an all unit discount structure this piecewise cost function adds significant complexity when included in supply chain management problems and is therefore often ignored due to solution time or tractability concerns we present and evaluate a new heuristic procedure which provides good solutions to problems involving all unit discount cost functions while significantly reducing solution times the general nature of this procedure does not require assumptions about the supply chain structure or policies and is therefore applicable in a wide range of settings

a new class of stock level dependent ordering policies for perishables with a short maximum shelf life many perishables such as fresh food and blood platelet concentrates are characterized by a short maximum shelf life as demand is often highly uncertain the outdating and shortages figures can be very high especially when frequent replenishment is not possible or inefficient due to fixed ordering cost we present a new class of stock level dependent ordering policies the s s q q policy which is a periodic review s s policy with the order quantity restricted by a minimum q and maximum q optimal weekday dependent parameter values are derived by dynamic programming and simulation the s s q q policy performs nearly optimal and improves the s s policies in many cases by 4 25

reliability of individual valuations of public and private goods choice consistency response time and preference refinement we examined the reliability of a large set of paired comparison value judgments involving public goods private goods and sums of money as respondents progressed through a random sequence of paired choices they were each given their response time decreased and they became more consistent apparently fine tuning their responses suggesting that respondents tend to begin a hypothetical value exercise with relatively imprecise preferences and that experience in expressing preference helps reduce that imprecision reliability was greater for private than for public good choices and greater for choices between a good and a monetary amount than for choices between two goods however the reliability for public good choices was only slightly lower than for the private goods published by elsevier b v

equality efficiency and market fundamentals the dynamics of international medical care reform public opinion surveys uniformly show low support for medical care systems in developed countries the longstanding conflict between equal access to care and efficient service provision partly explains this dissatisfaction but the trade off is particularly acute in medical care as new technologies developed over time have increased the cost of care and made the equity commitment even more expensive countries first dealt with rising costs by maintaining equal access and restricting total spending efficiency suffered however as a result many countries are considering a move away from spending controls and toward incentive based medical care reform

demand for beef from cattle administered growth hormones or fed genetically modified corn a comparison of consumers in france germany the united kingdom and the united states we compare consumer valuations of beef ribeye steaks from cattle produced without growth hormones or genetically modified corn in france germany the united kingdom and the united states results suggest that french consumers place a higher value on beef from cattle that have not been administered added growth hormones than u s consumers however valuations of non hormone treated beef are statistically indistinguishable across germany the united kingdom and the united states results also suggest that european consumers place a much higher value on beef from cattle that have not been fed genetically modified corn than u s consumers copyright 2003 oxford university press

does hospital competition harm equity evidence from the english national health service increasing evidence shows that hospital competition under fixed prices can improve quality and reduce cost concerns remain however that competition may undermine socio economic equity in the utilisation of care we test this hypothesis in the context of the pro competition reforms of the english national health service progressively introduced from 2004 to 2006 we use a panel of 32 482 english small areas followed from 2003 to 2008 and a difference in differences approach the effect of competition on equity is identified by the interaction between market structure small area income deprivation and year we find a negative association between market competition and elective admissions in deprived areas the effect of pro competition reform was to reduce this negative association slightly suggesting that competition did not undermine equity

a stochastic aggregate production planning model in a green supply chain considering flexible lead times nonlinear purchase and shortage cost functions in this paper we develop a stochastic programming approach to solve a multi period multi product multi site aggregate production planning problem in a green supply chain for a medium term planning horizon under the assumption of demand uncertainty the proposed model has the following features i the majority of supply chain cost parameters are considered ii quantity discounts to encourage the producer to order more from the suppliers in one period instead of splitting the order into periodical small quantities are considered iii the interrelationship between lead time and transportation cost is considered as well as that between lead time and greenhouse gas emission level iv demand uncertainty is assumed to follow a pre specified distribution function v shortages are penalized by a general multiple breakpoint function to persuade producers to reduce backorders as much as possible vi some indicators of a green supply chain such as greenhouse gas emissions and waste management are also incorporated into the model the proposed model is first a nonlinear mixed integer programming which is converted into a linear one by applying some theoretical and numerical techniques due to the convexity of the model the local solution obtained from linear programming solvers is also the global solution finally a numerical example is presented to demonstrate the validity of the proposed model

an enhanced robustness approach for managing supply and demand uncertainties abstract managing supply and demand uncertainties is a topic that receives increasing management attention due to 1 more price based competitions forcing firms purchase from cheaper but less reliable or unproven suppliers and 2 undesirable consequences of unaddressed demand fluctuations such as reduced service level financial loss reputational damage and loss of market share this paper presents a realistic production distribution planning model that is robust to common supply interruptions and demand variations a robustness approach named elastic p robustness is introduced that obviates the need to estimate probability distribution of random parameters when managing operational uncertainties of the supply chain the application of the proposed approach is investigated in an actual organization from discrete durable parts manufacturing sector our analyses of numerical results focus on 1 exploring different tactics for managing supply and demand variations 2 examining the benefits of concurrent consideration of supply and demand uncertainties 3 benchmarking the performance of the proposed approach against the popular robustness algorithms and 4 investigating the price of robustness under various supply and demand scenarios

review of inventory systems with deterioration since 2001 abstract this paper presents an up to date review of the advances made in the field of inventory control of perishable items deteriorating inventory the last extensive review on this topic dates back to 2001 goyal s k and giri b c recent trends in modeling of deteriorating inventory european journal of operational research 134 1 16 since then over two hundred articles on this subject have been published in the major journals on inventory control indicating the need for a new review we use the classification of goyal and giri based on shelf life characteristics and demand characteristics contributions are highlighted by discussing main system characteristics including price discounts backordering or lost sales single or multiple items one or two warehouses single or multi echelon average cost or discounted cash flow and payment delay

hospital utilization in mixed public private system evidence from australian hospital data this article investigates whether patients who used a mixture of private and public hospital care have higher total hospital utilization than those who exclusively used either public or private hospital care using australian hospital administrative data of heart disease patients we found that those who used a mixture of private and public care had the highest total hospital utilization our findings are robust to how utilization is measured and endogeneity between utilization and hospital type choice

an allocation and distribution model for perishable products this paper presents an allocation model for a perishable product distributed from a regional center to a given set of locations with random demands we consider the combined problem of allocating the available inventory at the center while deciding how these deliveries should be performed two types of delivery patterns are analyzed the first pattern assumes that all demand points receive individual deliveries the second pattern subsumes the frequently occurring case in which deliveries are combined in multistop routes traveled by a fleet of vehicles computational experience is reported

a stochastic model for risk management in global supply chain networks abstract with the increasing emphasis on supply chain vulnerabilities effective mathematical tools for analyzing and understanding appropriate supply chain risk management are now attracting much attention this paper presents a stochastic model of the multi stage global supply chain network problem incorporating a set of related risks namely supply demand exchange and disruption we provide a new solution methodology using the moreau yosida regularization and design an algorithm for treating the multi stage global supply chain network problem with profit maximization and risk minimization objectives

a bi objective stochastic programming model for a centralized green supply chain with deteriorating products in recent years consumers and legislation have been pushing companies to design their activities in such a way as to reduce negative environmental impacts more and more it is therefore important to examine the optimization of total supply chain costs and environmental impacts together however because of the recycling of deteriorated items the environmental impacts of deteriorating items are more significant than those of non deteriorating ones the objective of this paper is to develop a stochastic mathematical model and to propose a new replenishment policy in a centralized supply chain for deteriorating items in this model we consider inventory and transportation costs as well as the environmental impacts under uncertain demand several transportation vehicles producing various greenhouse gas ghg levels are considered the best transportation vehicles and inventory policy are determined by finding a balance between financial and environmental criteria in this way we develop a linear mathematical model and present a numerical example from the real world to demonstrate its applicability and effectiveness we then perform a sensitivity analysis and provide some managerial insights finally more promising directions are suggested for future research

handling uncertainty in agricultural supply chain management a state of the art given the evolution in the agricultural sector and the new challenges it faces managing agricultural supply chains efficiently has become an attractive topic for researchers and practitioners against this background the integration of uncertain aspects has continuously gained importance for managerial decision making since it can lead to an increase in efficiency responsiveness business integration and ultimately in market competitiveness in order to capture appropriately the uncertain conjuncture of most agricultural real life applications an increasing amount of research effort is especially dedicated to treating uncertainty in particular quantitative modeling approaches have found extensive use in agricultural supply chain management this paper provides an overview of the latest advances and developments in the application of operations research methodologies to handling uncertainty occurring in the agricultural supply chain management problems it seeks to i offer a representative overview of the predominant research topics ii highlight the most pertinent and widely used frameworks and iii discuss the emergence of new operations research advances in the agricultural sector the broad spectrum of reviewed contributions is classified and presented with respect to three most relevant discerned features uncertainty modeling types programming approaches and functional application areas ultimately main review findings are pointed out and future research directions which emerge are suggested

socioeconomic inequality of access to healthcare does choice explain the gradient equity of access is a key policy objective in publicly funded healthcare systems however observed inequalities of access by socioeconomic status may result from differences in patients choices using data on non emergency coronary revascularisation procedures in the english national health service we found substantive differences in waiting times within public hospitals between patients with different socioeconomic status up to 35 difference or 43 days between the most and least deprived population quintile groups using selection models with differential distances as identification variables we estimated that only up to 12 of these waiting time inequalities can be attributed to patients choices of hospital and type of treatment heart bypass versus stent residual inequality after allowing for choice was economically significant patients in the least deprived quintile group benefited from shorter waiting times and the associated health benefits were worth up to 850 per person

climate change and dietary choices how can emissions of greenhouse gases from food consumption be reduced abstract results from an analysis of greenhouse gas emissions and energy consumption during the life cycle of carrots tomatoes potatoes pork rice and dry peas consumed in sweden are presented and discussed the life cycle is delineated to the part of the production chain prior to purchase by the consumer the study shows that emissions expressed in g co2 equivalents are highest for pork and rice and lowest for potatoes carrots and dry peas the most important stages of emissions in the life cycle are identified for each of the different food items crop farming is the most important stage for rice and tomatoes while rearing of animals is the most important stage for pork and storage is the most important stage for carrots comparison with an energy analysis shows that important stages in the life cycle of food may be under evaluated when energy only is accounted for this may lead to a sub optimisation of pollution control exemplified by the case of transportation also it is shown that the choice of functional unit has a decisive influence on the outcome of the study the recommendation is to compare whole meals or diets with the same nutritional qualities a comparison of four meals composed of the food items under analysis shows that a meal with tomatoes rice and pork has nine times higher emissions than a meal made from potatoes carrots and dry peas emissions of greenhouse gases from consumption patterns based on the food items analysed are compared with an assumed sustainable limit of greenhouse gas emissions the conclusion is that current food consumption patterns in the developed countries exceed the level of sustainability by at least a factor of 4 prospects for achieving sustainable food consumption patterns are questionable in view of current trends in food demand

parental altruism and the value of avoiding acute illness are kids worth more than parents abstract a model describing parents preferences to relieve their own and their children s acute illnesses is estimated using stated preference data estimated marginal rates of substitution mrs between child and parent illness are about two indicating that parents value children s illness attributes twice as highly as their own the mrs is larger for younger children falls toward unity as the child approaches adulthood and appears to reflect parental altruism rather than parent child differences in initial health or illness costs intra family allocations may compensate for chronic health impairments parents willingness to pay to avoid own or child illness increases with income declines with fertility increases at a decreasing rate with duration and number of symptoms and depends on perceived discomfort and activity restrictions current methods of assessing morbidity benefits of environmental regulations may understate substantially the value of children s health particularly in african american families

a multi objective robust optimization model for multi product multi site aggregate production planning in a supply chain under uncertainty abstract manufacturers need to satisfy consumer demands in order to compete in the real world this requires the efficient operation of a supply chain planning in this research we consider a supply chain including multiple suppliers multiple manufacturers and multiple customers addressing a multi site multi period multi product aggregate production planning app problem under uncertainty first a new robust multi objective mixed integer nonlinear programming model is proposed to deal with app considering two conflicting objectives simultaneously as well as the uncertain nature of the supply chain cost parameters of the supply chain and demand fluctuations are subject to uncertainty then the problem transformed into a multi objective linear one the first objective function aims to minimize total losses of supply chain including production cost hiring firing and training cost raw material and end product inventory holding cost transportation and shortage cost the second objective function considers customer satisfaction through minimizing sum of the maximum amount of shortages among the customers zones in all periods working levels workers productivity overtime subcontracting storage capacity and lead time are also considered finally the proposed model is solved as a single objective mixed integer programming model applying the lp metrics method the practicability of the proposed model is demonstrated through its application in solving an app problem in an industrial case study the results indicate that the proposed model can provide a promising approach to fulfill an efficient production planning in a supply chain

modeling an inventory routing problem for perishable products with environmental considerations and demand uncertainty the transition to sustainable food supply chain management has brought new key logistical aims such as reducing food waste and environmental impacts of operations in the supply chain besides the traditional cost minimization objective traditional assumptions of constant distribution costs between nodes unlimited product shelf life and deterministic demand used in the inventory routing problem irp literature restrict the usage of the proposed models in current food logistics systems from this point of view our interest in this study is to enhance the traditional models for the irp to make them more useful for the decision makers in food logistics management therefore we present a multi period irp model that includes truck load dependent and thus route dependent distribution costs for a comprehensive evaluation of co2 emission and fuel consumption perishability and a service level constraint for meeting uncertain demand a case study on the fresh tomato distribution operations of a supermarket chain shows the applicability of the model to a real life problem several variations of the model each differing with respect to the considered aspects are employed to present the benefits of including perishability and explicit fuel consumption concerns in the model the results suggest that the proposed integrated model can achieve significant savings in total cost while satisfying the service level requirements and thus offers better support to decision makers

coordinated supply chain management abstract historically the three fundamental stages of the supply chain procurement production and distribution have been managed independently buffered by large inventories increasing competitive pressures and market globalization are forcing firms to develop supply chains that can quickly respond to customer needs to remain competitive these firms must reduce operating costs while continuously improving customer service with recent advances in communications and information technology as well as a rapidly growing array of logistics options firms have an opportunity to reduce operating costs by coordinating the planning of these stages in this paper we review the literature addressing coordinated planning between two or more stages of the supply chain placing particular emphasis on models that would lend themselves to a total supply chain model finally we suggest directions for future research

performance evaluation and a flow allocation decision model for a sustainable supply chain of an apparel industry abstract there is a growing concern that business enterprises and their supply chains focus primarily on economic activities and ignore their impact on the environment and society this paper aims to help decision makers managers and practitioners to achieve economic growth societal development and environmental protection by developing sustainable supply chain performance measures and proposes a partner selection and flow allocation decision making model survey data from 278 business organizations from the indian apparel industry supply chain network were used and an integrated method of structural equation modeling fuzzy analytical hierarchy process and fuzzy multi objective linear programming was applied to the proposed model the results of the structural equation modeling analysis indicate that the survey respondents considered sustainable production performance to be of prime importance which thus indicates its significance in developing a sustainable supply chain for the apparel industry to illustrate the use of the proposed model for partner selection and flow allocation decision making real time data from an apparel manufacturer are presented optimal results were obtained for two strategies sustainability and cost saving to show a cost benefit trade off when developing a sustainable supply chain using comparative performance a decision maker can choose an appropriate strategy based on cost benefit analysis of the presented trade offs

do parents benefit it from school health risk reduction the choice experiment method was applied to determine parent s preferences and monetaryvalues of risk reductions on three related health issues in school lead contamination inschool drinking water diarrhea from food contamination and accident from outdoor playground data were obtained from face to face interview of 672 respondents in three regions ofthailand lead contamination is the greatest concern among parents as reflected by thelargest coefficients of risk reduction levels and the highest amount of monetary values elicitedfrom parent s preferences the other two issues are considered of equal importance however parents seem insensitive to the changes of risk reductions of these two issues revealingthe scope insensitivity given the scope insensitivity choice experiment may be seen as apromising method to determine preferences and monetary values of health related issuesthat have no appropriate or precise financial proxy available keywords non market valuation safety in school health risk reduction jel classification d61 i10 i31

assessing the role of us agriculture in reducing greenhouse gas emissions and generating additional environmental benefits abstract this study measures the changes in greenhouse gas ghg emissions from us crop production under a scenario where farmers face higher energy prices with the implementation of the kyoto protocol the focus is on predicting the impact on direct and indirect energy resource use and measuring the changes in specific ghgs the study also assesses the potential for additional environmental benefits from the changes in agricultural resource use the analyses rely on the results from a calibrated mathematical programming model of regional us crop production the model accounts for input substitution when farmers are faced with external shocks the results suggest that when energy prices increase there is a relatively small decrease in total harvested acreage but a more significant drop in the use of energy intensive resources overall ghg emissions from us crop production decrease by 20 suggesting agriculture is more effective in abating ghg emissions than the other sectors of us economy there is also a good potential for additional positive environmental externalities from the decreases in resources used in crop production

coordinating clearance markdown sales of seasonal products in retail chains in this paper we propose a methodology to set prices of perishable items in the context of a retail chain with coordinated prices among its stores and compare its performance with actual practice in a real case study we formulate a stochastic dynamic programming problem and develop heuristic solutions that approximate optimal solutions satisfactorily to compare this methodology with current practices in the industry we conducted two sets of experiments using the expertise of a product manager of a large retail company in chile in the first case we contrast the performance of the proposed methodology with the revenues obtained during the 1995 autumn winter season in the second case we compare it with the performance of the experienced product manager in a simulation game setting in both cases our methodology provides significantly better results than those obtained by current practices

does hospital competition save lives evidence from the english nhs patient choice reforms recent substantive reforms to the english national health service expanded patient choice and encouraged hospitals to compete within a market with fixed prices this study investigates whether these reforms led to improvements in hospital quality we use a difference in difference style estimator to test whether hospital quality measured using mortality from acute myocardial infarction improved more quickly in more competitive markets after these reforms came into force in 2006 we find that after the reforms were implemented mortality fell i e quality improved for patients living in more competitive markets our results suggest that hospital competition can lead to improvements in hospital quality

is hospital competition socially wasteful we study the consequences of hospital competition for medicare beneficiaries heart attack care from 1985 to 1994 we examine how relatively exogenous determinants of hospital choice such as travel distances influence the competitiveness of hospital markets and how hospital competition interacts with the influence of managed care organizations to affect the key determinants of social welfare expenditures on treatment and patient health outcomes in the 1980s the welfare effects of competition were ambiguous but in the 1990s competition unambiguously improves social welfare increasing hmo enrollment over the sample period partially explains the dramatic change in the impact of hospital competition

an optimization approach for supply chain management models with quantity discount policy abstract owing to the difficulty of treating nonlinear functions many supply chain management scm models assume that the average prices of materials production transportation and inventory are constant this assumption however is not practical vendors usually offer quantity discounts to encourage the buyers to order more and the producer intends to discount the unit production cost if the amount of production is large this study solves a nonlinear scm model capable of treating various quantity discount functions simultaneously including linear single breakpoint step and multiple breakpoint functions by utilizing the presented linearization techniques such a nonlinear model is approximated to a linear mixed 0 1 program solvable to obtain a global optimum

green supply chain design a mathematical modeling approach based on a multi objective optimization model abstract increasing levels of industrialization of developed nations associated with globalization trends have been creating new challenges to supply chain management scm for decades the main focus of scm has been on efficient ways of managing the flows through complex networks of supplier producers and customers more recently and as a result of the exponential increase of energy and materials consumption rates of energy and materials sustainable development arise as an urgent issue and new approaches to scm are required to incorporate environmental and economic concerns in the design of supply chains in this paper a new green supply chain gsc design approach has been proposed to deal with the trade offs between environmental and financial issues in order to reduce negative impacts on the environment caused by the increasing levels of industrialization the new approach incorporates a closed loop network to accommodate the reprocessing paradigm of disposal products and a multi objective optimization mathematical model to minimize overall costs and carbon dioxide emissions when setting the supply chain optimization process is performed using three scalarization approaches namely weighted sum method weighted tchebycheff and augmented weighted tchebycheff computational results are analyzed to identify the advantages and drawbacks of each approach the model was tested in a case study and results allowed to identify the capability of the model to deal with the trade offs between the costs and environmental issues as well as to identify its main limitation when addressing real size problems

assessing the impact of cost optimization based on infrastructure modelling on co2 emissions traditionally logistics design is driven by a need to reduce costs and improve customer service recently the environmental concerns from transport have been increasingly discussed the traffic levels and associated energy consumption are influenced by supply chain structure modal split and vehicle utilization this paper aims to assess the impact of the traditional cost optimization approach to strategic modelling on overall logistics costs and co2 emissions by taking into account the supply chain structure number of depots and different freight vehicle utilization ratios 90 75 and 60 the simulation model based on a european case study from the automotive industry considers strategic and operational level decisions simultaneously the analysis shows that the optimum design based on costs does not necessary equate to an optimum solution for co2 emissions therefore there is a need to address economical and environmental objectives explicitly as part of the logistics design

a hybrid l shaped method to solve a bi objective stochastic transshipment enabled inventory routing problem abstract recently greenness has become a very much needed condition in the transportation industry in this study we develop a green transshipment enabled model for the inventory routing problem irp in a many to one distribution network where demand for each product is realistically assumed to be uncertain the proposed framework is a bi objective stochastic programming model the first objective function aims to minimize the expected value of the supply chain costs including inevitable shortage costs the second objective function aims to minimize the total quantity of the greenhouse gas ghg emission produced by the vehicles and disposed products we introduce a very practical innovative application of transshipment option to control transportation cost reduce ghg emissions and absorb the uncertainty in order to solve the proposed model an efficient hybrid algorithm combining l shaped method a sort of decomposition approach for stochastic optimization and compromise programming a well known approach for multi objective optimization is proposed the results show that how companies can make a reasonable tradeoff between the cost and environmental concerns and emphasize the role of transshipment option as a lever to improve both economic and environmental performance and absorb the demand fluctuations

free to choose reform choice and consideration sets in the english national health service choice in public services is controversial we exploit a reform in the english national health service to assess the effect of removing constraints on patient choice we estimate a demand model that explicitly captures the removal of the choice constraints imposed on patients we find that post removal patients became more responsive to clinical quality this led to a modest reduction in mortality and a substantial increase in patient welfare the elasticity of demand faced by hospitals increased substantially post reform and we find evidence that hospitals responded to the enhanced incentives by improving quality this suggests greater choice can raise quality

a robust optimization model for cellular manufacturing system into supply chain management abstract in this paper a new mathematical model is presented for a cellular manufacturing system into supply chain design with labor assignment this paper considers important manufacturing features thoroughly such as multiple plant locations multi market allocations with production planning and various part mix the proposed model aims at minimizing the total cost of holding inter cell material handling external transportation fixed cost for producing each part in each plant machine and labor salaries it is assumed that the demands of products are uncertainty in three scenarios optimistic pessimistic and normal also a robust optimization approach is then developed to solve the proposed model and find the best solution the robustness and performance of the proposed model are explained in terms of an industrial case from a typical equipment manufacturer this case study provides the researchers and practitioners to better understand the importance of designing robust optimization and cell formation in the supply chain management from a practical point of view

modelling food logistics networks with emission considerations the case of an international beef supply chain intrinsic characteristics of food products and processes along with growing sustainability concerns lead to the need for decision support tools that can integrate economic considerations with quality preservation and environmental protection in food supply chains in this study we develop a multi objective linear programming molp model for a generic beef logistics network problem the objectives of the model are i minimizing total logistics cost and ii minimizing total amount of greenhouse gas emissions from transportation operations the model is solved with the ee constraint method this study breaks away from the literature on logistics network models by simultaneously considering transportation emissions affected by road structure vehicle and fuel types weight loads of vehicles traveled distances return hauls and product perishability in a molp model we present computational results and analysis based on an application of the model on a real life international beef logistics chain operating in nova andradina mato grosso do sul brazil and exporting beef to the european union trade off relationships between multiple objectives are observed by the derived pareto frontier that presents the cost of being sustainable from the point of reducing transportation emissions the results from the pie chart analysis indicate the importance of distances between actors in terms of environmental impact moreover sensitivity analysis on practically important parameters shows that export ports capacities put pressure on the logistics system decreasing fuel efficiency due to the bad infrastructure has negative effects on cost and emissions and green tax incentives result in economic and environmental improvement

market opportunities genetic endowments and intrafamily resource distribution child survival in rural india the authors examine how intrafamily resource allocations respond to changes in economic conditions and to genetic differences in children by estimating the determinants of variations in the sex specific survival differentials of rural indian children based on standard census and household survey data they explore in particular the hypothesis that such differences are related to the relative returns to survival with households selectively allocating resources to children in response to variation in sex differences in their expected earnings opportunities as adults data are from the 1961 census and a 1971 household survey excerpt

competition and equity in health care markets we provide a model where hospitals compete on quality under fixed prices to investigate how hospital competition affects i quality differences between hospitals and as a result ii health inequalities across hospitals and patient severities the answer to the first question is ambiguous and depends on factors related to both demand and supply of health care whether competition increases or reduces health inequalities depends on the type and measure of inequality health inequalities due to the postcode lottery are more likely to decrease if the marginal health gains from quality decrease at a higher rate whereas health inequalities between high and low severity patients decrease if patient composition effects are sufficiently small we also investigate the effect of competition on health inequalities as measured by the gini and the generalised gini coefficients and highlight differences compared to the simpler dispersion measures

production and shipment lot sizing in a vendor buyer supply chain with transportation cost abstract previous research on the joint vendor buyer problem focused on the production shipment schedule in terms of the number and size of batches transferred between the two parties it is a fact that transportation cost is a major part of the total operational cost however in most joint vendor buyer models the transportation cost is only considered implicitly as a part of fixed setup or ordering cost and thus is assumed to be independent of the size of the shipment as such the effect of the transportation cost is not adequately reflected in final planning decisions there is a need for models involving transportation cost explicitly for better decision making in this study we analyze the vendor buyer lot sizing problem under equal size shipment policy we introduce the complete solution of the problem in an explicit and extended manner that has not existed in the literature we incorporate transportation cost explicitly into the model and develop optimal solution procedures for solving the integrated models all unit discount transportation cost structures with and without over declaration have been considered numerical examples are presented for illustrative purpose

production planning for a deteriorating item with stochastic demand and consumer choice abstract this paper concerns inventory control of a deteriorating product with non negligible procurement lead time that perishes after a known number of periods demand for fresh products during each period is represented as a random variable with known probability distribution but only a fraction of this demand is satisfied during any given period due to item deterioration we derive the expected profit function for a two period problem with one production opportunity before the selling season begins and a single product type with two period shelf life for the case in which demand during both periods is uniform independent and identically distributed we identify sufficient conditions for the existence of an optimal solution and present a straightforward procedure for obtaining the solution

a two stage stochastic programming model for inventory management in the blood supply chain managing inventories in the blood supply chain is a challenging task mainly due to the uncertain nature of the demand for blood units the perishable nature of the blood and a strong subjective bias towards criteria other than cost minimisation in this paper we propose a two stage stochastic programming model for defining optimal periodic review policies for red blood cells inventory management that focus on minimising operational costs as well as blood shortage and wastage due to outdating taking into account perishability and demand uncertainty the adoption of this framework allows the consideration of more general stochastic processes to model the demand uncertainty than approaches currently available in literature moreover this framework renders a model that can be solved efficiently by general purpose off the shelf optimisation software to illustrate the potential benefits of adopting the proposed model to support the definition of optimal blood inventory control policies a case study is presented considering realistic data representing the daily demand for blood which was generated using the average and standard deviation of the demand for eight types of blood results suggest meaningful insights concerning practices that could lead to improvement in the blood supply chain performance in particular we observed that it would be possible to revise the current inventory control policies by reducing current target levels to diminish wastage and total cost without compromising the service level finally the consideration of blood substitutions showed further improvement in the performance of the blood inventory management system