managing without growth abstract there are three main arguments why developed countries should consider managing without growth 1 continued economic growth worldwide is not an option owing to environmental and resource constraints and so developed countries should leave room for growth in developing countries where the benefits of growth are evident 2 in developed countries growth has become uneconomic in the sense that it detracts more from well being than it adds and 3 economic growth in developed countries is neither necessary nor sufficient for meeting specific policy objectives such as full employment no poverty and protection of the environment this paper explores various growth scenarios for canada over the medium range to 2020 using lowgrow a dynamic simulation model after describing lowgrow a scenario is presented that shows conditions under which the rate of unemployment in canada could be reduced to historically low levels poverty eliminated and greenhouse gas emissions reduced to comply with canada s commitment under the kyoto protocol without relying on economic growth this is not to say that zero growth should itself become a policy objective rather that the dependence on and defence of economic growth should not be an obstacle to fulfilling more specific welfare enhancing objectives of full employment eliminating poverty and protecting the environment the paper concludes with some policy implications for managing without growth followed by an annex which provides a technical description of lowgrow

a multiobjective approach to vendor selection abstract purchases from vendors involve significant costs for many firms decisions related to these purchases include the selection of vendors and the determination of order quantities to be placed with the selected vendors such decisions are frequently multiobjective in nature that is they are evaluated by more than one criterion at least 23 criteria for various vendor selection problems have been identified in this article we present a multiobjective approach to systematically analyze the inherent tradeoffs involved in multicriteria vendor selection problems the approach is motivated by and demonstrated with an actual purchasing problem facing a division of a fortune 500 company

production lot sizing and carbon emissions under cap and trade and carbon tax regulations cap and trade and carbon tax are two emission regulations widely used to curb the carbon emissions generated from firms based on economic order quantity eoq model this paper examines the production lot sizing issues of a firm under these two regulations respectively the optimal lot size and emissions under the two regulations are achieved we then investigate the impacts of production and regulation parameters on the optimal lot size and emissions furthermore we compare the firm s optimal carbon emissions under the two regulations it is found that under the cap and trade regulation the firm s decisions of the optimal emissions as well as permits trading depend on the differentiated permits trading prices if setup incurs the same cost as holding incurs per unit of generated emissions both regulations always lead to the same optimal emissions which is also equal to that without emission regulation otherwise neither regulation always leads to lower emissions than the other does

order splitting with multiple capacitated suppliers this paper studies an integrated decision making model for a supply chain system where a manufacturer faces a price sensitive demand and multiple capacitated suppliers two issues that are often considered separately in the literature the goal is to maximize total profit by determining an optimal selling price and at the same time acquiring enough supplying capacity the problem is proved to be np hard in the ordinary sense a heuristic algorithm and an optimal dynamic programming algorithm are developed computational experiments are conducted to study the efficiency and effectiveness of the algorithms some managerial insights are observed

on inventory control of product recovery systems subject to environmental mechanisms abstract the aim of this paper is to study the impact of inventory control in reducing the carbon footprint of an organization through a stochastic inventory model our research extends the traditional minimization cost problem by incorporating environmental legislation we consider a finite horizon closed loop system whereby decisions are subject to an emissions trading scheme and to random demand and returns demand can be satisfied by two sources the primary source is environmentally friendly but expensive whereas the second is cost effective but with negative environmental consequences the problem is formulated as a stochastic dynamic problem where replenishment and carbon management decisions must be made at each period the objective is to describe how replenishment and carbon management strategies are affected by environmental constraints in particular considering the computation restriction of dynamic programming in order to extend the results we propose a genetic algorithm to find near optimal solutions for larger instances a sensitivity analysis is performed to identify the impact of carbon allowance prices emission cap and other environmental factors in the decision making process the results indicate that environmental strategies and their factors have an impact on replenishment decisions there is an emission cap from which a company must focus on strategic decisions rather than on tactical and operational decisions in addition if the carbon allowance price is such that the environmental benefit absorbs the cost of less polluting technology a change in the inventory policy must be made

fuzzy multiobjective linear model for supplier selection in a supply chain abstract within new strategies for purchasing and manufacturing suppliers play a key role in achieving corporate competition hence selecting the right suppliers is a vital component of these strategies in practice vagueness and imprecision of the goals constraints and parameters in this problem make the decision making complicated in spite of the importance of the problem the literature on this subject is relatively scarce in this paper a fuzzy multiobjective linear model is developed to overcome the vagueness of the information for the first time in a fuzzy supplier selection problem an asymmetric fuzzy decision making technique is applied to enable the decision maker to assign different weights to various criteria the model is explained by an illustrative example

stability of zero growth economics analysed with a minskyan model abstract as humanity is becoming increasingly confronted by earth s finite biophysical limits there is increasing interest in questions about the stability and equitability of a zero growth capitalist economy most notably if one maintains a positive interest rate for loans can a zero growth economy be stable this question has been explored on a few different macroeconomic models and both yes and no answers have been obtained however economies can become unstable whether or not there is ongoing underlying growth in productivity with which to sustain growth in output here we attempt for the first time to assess via a model the relative stability of growth versus no growth scenarios the model employed draws from keen s model of the minsky financial instability hypothesis the analysis focuses on dynamics as opposed to equilibrium and scenarios of growth and no growth of output gdp are obtained by tweaking a productivity growth input parameter we confirm that with or without growth there can be both stable and unstable scenarios to maintain stability firms must not change their debt levels or target debt levels too quickly further according to the model the wages share is higher for zero growth scenarios although there are more frequent substantial drops in employment

a multi objective supplier selection model under stochastic demand conditions abstract supplier selection is a typical multi criteria decision problem attracting great attention recently cost quality delivery and flexibility are generally involved in the supplier selection decision making in this paper a measurement of supplier flexibility is extended to consider demand quantity and timing uncertainties comprehensively a multi objective supplier selection model is developed under stochastic demand conditions stochastic supplier selection is determined with simultaneous consideration of the total cost the quality rejection rate the late delivery rate and the flexibility rate involving constraints of demand satisfaction and capacity using a problem specific genetic algorithm computational results are presented

an improved model for supplier selection under capacity constraint and multiple criteria abstract ghodsypour and o brien 2001 the total cost of logistics in supplier selection under conditions of multiple sourcing multiple criteria and capacity constraint international journal of production economics 73 1 15 27 study multiple sourcing problem with multiple criteria and capacitated suppliers considering the buyer s quality requirements as a constraint they develop a mixed integer non linear programming model to find the least cost cyclic ordering policy for the buyer they propose to solve the model by enumerating over all possible supplier combinations although the problem is interesting and their analysis is correct we point out two issues with their assumptions namely capacitated suppliers and cyclic ordering policy we discuss two different capacitated supplier settings i long run average annual capacity and ii exact annual capacity first under long run average annual capacity assumption we propose a model which provides the same or a better solution and is much easier to solve than their model then we discuss how to modify our and their models to handle exact annual capacity assumption

consistency and stability analysis of models of a monetary growth imperative ist das streben nach wirtschaftswachstum eine frage des politischen willens oder eine notwendige bedingung fur okonomische stabilitat es ist umstritten ob solche wachstumszwange im heutigen geldsystem bestehen und einen konflikt mit nachhaltigkeit hervorrufen zur untersuchung der ersten behauptung dass zinseszinsen einen wachstumszwang hervorrufen stellen wir funf post keynesianische modelle vor und fuhren eine stabilitatsanalyse im parameterraum durch eine stationare okonomie mit spar und investitionsquote von null kann bei positivem zinssatz erreicht werden wenn der parameter konsum aus dem bestand oberhalb eines schwellenwerts liegt der mit dem zinssatz ansteigt die andere behauptung dass die bildung von gewinnrucklagen aus den zinseinnahmen der banken zu einem wachstumszwang fuhrt basiert auf modellen des monetaren kreislaufs die wir fur widerlegbar halten ihre bilanzierung ist inkonsistent und eine zentrale modellannahme ist nicht theoretisch begrundet aber die hauptursache des wachstumszwangs das eigenkapital der bank muss gesteigert werden selbst wenn ihre verbindlichkeiten nicht wachsen was eine diskrepanz zwischen der intention der autoren und dem eigentlichen modell ist wir kommen zum schluss dass das heutige geldsystem auf der basis von zinstragendem kreditgeld mit privaten banken nicht zu einem inharenten wachstumszwang fuhrt falls der stationare zustand instabil ist liegt es an entscheidungen wirtschaftlicher agenten und nicht an struktureller unvermeidbarkeit

purchasing raw materials with uncertain fluctuating prices on identifie les differentes etapes de la decision d achat des matieres premieres ainsi que les differentes approches et les aptitudes requises on decrit plusieurs methodes et modeles proposes et appliques aux differentes etapes les aspects importants etant l inadequation des modeles de stocks classiques l application de la programmation lineaire au probleme de melange la prevision des prix a l aide de l econometrie et de l analyse des series temporelles et la prise de decision sequentielle pour l achat au jour le jour

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

a serial inventory system with supplier selection and order quantity allocation given the prevalence of both supplier selection and inventory control problems in supply chain management this article addresses these problems simultaneously by developing a mathematical model for a serial system this model determines an optimal inventory policy that coordinates the transfer of items between consecutive stages of the system while properly allocating orders to selected suppliers in stage 1 in addition a lower bound on the minimum total cost per time unit is obtained and a 98 effective power of two pot inventory policy is derived for the system under consideration this pot algorithm is advantageous since it is simple to compute and yields near optimal solutions

multi product inventory model for cold items with cost and emission consideration while sharing storage and transportation units is common for many product types cold items usually have different temperature requirements and as a result not all items can share a holding transportation unit consequently the type of products and their compatibility with other products needs to be considered in the inventory model in this paper we propose multi product inventory models for cold items the models determine the inventory levels that minimize either the cost or carbon equivalent emissions we model the compatibility of items as a constraint in the inventory model to solve the model we first find an appropriate family of products that can share a storage transportation unit then for each family of products we develop an approximate solution method to determine the order quantity of each product within a family numerical experiments demonstrate the solution procedure and provide managerial insights into cold item inventory policies

non stationary stochastic inventory lot sizing with emission and service level constraints in a carbon cap and trade system firms worldwide are taking major initiatives to reduce the carbon footprint of their supply chains in response to the growing governmental and consumer pressures in real life these supply chains face stochastic and non stationary demand but most of the studies on inventory lot sizing problem with emission concerns consider deterministic demand in this paper we study the inventory lot sizing problem under non stationary stochastic demand condition with emission and cycle service level constraints considering carbon cap and trade regulatory mechanism using a mixed integer linear programming model this paper aims to investigate the effects of emission parameters product and system related features on the supply chain performance through extensive computational experiments to cover general type business settings and not a specific scenario results show that cycle service level and demand coefficient of variation have significant impacts on total cost and emission irrespective of level of demand variability while the impact of product s demand pattern is significant only at lower level of demand variability finally results also show that increasing value of carbon price reduces total cost total emission and total inventory and the scope of emission reduction by increasing carbon price is greater at higher levels of cycle service level and demand coefficient of variation the analysis of results helps supply chain managers to take right decision in different demand and service level situations

supply chain focus dependent supplier selection problem increasing globalization diversity of the product range and increasing customer awareness are making the market s highly competitive thereby forcing different supply chains to adapt to different stimuli on a continuous basis it is also well recognized that overall supply chain focus should be given an overriding priority over the individual goals of the players if one were to improve overall supply chain surplus among all the possible order winners cost and responsiveness seem to be the most significant metrics based on which majority of the supply chains compete with each other supplier selection problem is one of the crucial problems that need to be addressed in configuring a supply chain that could have far reaching ramifications on the total supply chain costs and order winnability our model that considers inventory costs and the supply chain cycle time reduction costs would aid a supply chain manager to make informed decisions with regard to supplier selection problem at any stage dependent upon the priorities attached to supply chain costs and cycle time inventory related costs and responsiveness related costs are the two primary cost elements that are considered in this model we are also making use of a novel dimensionless quantity called the coefficient of inverse responsiveness that not only facilitates the introduction of responsiveness related costs into the model but also improves the scalability and simplifies the analysis and interpretation of the results based on the strategic model developed we offer some very interesting managerial insights with respect to the effect of cost efficient operations and or location and cost of volume related flexibility at a stage on alternate suppliers which in turn affects the overall supply chain performance

carbon emissions and energy effects on a two level manufacturer retailer closed loop supply chain model with remanufacturing subject to different coordination mechanisms abstract this paper presents two models classical and vmi cs coordination for a two level closed loop supply chain with a manufacturer and a retailer with a facility to remanufacture used items the paper considers three critical environmental issues which are the energy used in production manufacturing and remanufacturing processes ghg emissions from production and transportation activities subject to a penalty tax and the number of times to remanufacture recover a used item numerical results show that the traditional optimization approach which minimises the sum of inventory related costs suggested less remanufacturing fewer recovery times and more ghg emissions and energy usage a result of operating at high production rates the vmi cs model was shown to be more economical than the classical model for a wide range of manufacturing rates but not necessarily a more environmentally responsible choice an extensive numerical analysis was conducted to enrich the discussion and to draw some managerial insights on how to make environmentally conscious decisions

sustainable economic production quantity models for inventory systems with shortage abstract recently new economic order production quantity models have shifted away from focusing only on economic issues and towards combined economic environmental concerns because of sustainable development goals despite this shift only a few works have addressed sustainable economic production quantity epq the theoretical sustainable eoq and epq models are basic models that ignore many real life conditions such as the possibility of stock out in inventory systems in this paper we develop four new sustainable economic production quantity models that consider different shortage situations to find optimal values of inventory system variables we solve four independent profit maximization problems for four different situations these proposed models include a basic model in which shortages are not allowed and when shortages are allowed the lost sale full backordering and partial backordering models can be selected by operations managers depending on the manufacturer s motivation to improve service levels we have also proposed an algorithm for determining optimum values of the decision variables for these sustainable economic production quantity models finally the formulated models are explained with some different examples and the obtained results have been analyzed and discussed these results show that the sustainable economic production quantity with partial backordering model is a general and more realistic model that can be used in many real cases with a reasonable profit amount compared with the three other proposed models

customer regulatory and competitive pressure as drivers of environmental innovation we develop an economic analysis in order to examine the effects of consumer regulatory and competitive pressure on firm investments in environmentally friendly production specifically we ask why do firms vary in their levels of environmental innovation under what conditions are such pressures effective in bringing about environmental innovation we first consider a monopolist who faces the twin pressures of reduced customer demand and regulatory penalties as a result of its emissions in response to these pressures the firm has the opportunity to make a costly investment in reduction of emissions secondly we consider a competitive scenario in which two firms compete for environmentally sensitive customers solving our model we find that pressure has the intended effect as long as the firm s initial level of emissions is below a certain threshold if the emissions are above this threshold we find that pressure might have an adverse effect on the firm s environmental investment and that subsidies that support environmental innovation can be a better alternative we also show that competition over environmentally sensitive customers can improve the effectiveness of environmental pressures

an ecological macroeconomics model the energy transition in the eu abstract the energy roadmap 2050 er2050 is committed to achieve the european union s emissions mitigation goals by reducing energy use and a transition to renewables the macroeconomic impacts of the ref16 and euco scenarios of this strategy have been reported to entail an absolute decoupling between gdp growth and energy use the aim of this paper is assessing the er2050 targets with a novel modelling methodology based on post keynesian economics i e demand led economic growth and ecological economics i e taking into account absolute biophysical energy availability constrains to economic growth thus this article presents the economy module of the integrated assessment model medeas europe combining system dynamics and input output analysis and evaluates the er2050 targets under different scenarios regarding primary income distribution foreign trade labour productivity industrial policy and working time reduction our results show that gdp growth and employment creation may be halted due to energy scarcity if the er2050 targets are met even considering great energy efficiency gains in addition the renewables share would increase enough to reduce the energy imports dependency but not sufficiently to meet the emissions targets only a post growth scenario would be able to meet the climate goals and maintain the level of employment

overcoming accumulation is a capitalist steady state economy possible abstract this article critically reviews the case for a steady state zero growth economy posing the question whether such an economy can be stable and socially just given that in the current global economy lack of growth is synonymous with crisis the sse thesis is analysed within a framework of marxian political economy concluding that a stable and just sse is possible but not feasible within the social relations of capitalism using the marxian analysis of capital accumulation the article then considers whether the reforms proposed by ecological economists can form an effective countervailing force to the drive for accumulation the conclusion is that such reforms can be successful but only in so far as they are complemented and brought to their logical conclusion by a wider attempt to transcend the capitalist relations of production

inventory management under joint product recovery and cap and trade constraints abstract the influence of environmental legislation in inventory control policies is explored previous work on product recovery is extended using the introduction of a cap and trade mechanism in an infinite horizon inventory system in which demand and returns are uncertain demand is met through two different sources namely manufacturing and remanufacturing which differ in cost and greenhouse gas emissions the main contributions of this paper are 1 comparison of system operation in terms of cost and environmental performance under conventional and green inventory policies and 2 managerial insights into the structure of green inventory policies to illustrate the impact of a cap and trade scheme a numerical example is used we solved the problem as a markov decision process and characterized the inventory policies based on the optimal replenishment strategy we also conducted a sensitivity analysis to examine the effect of underlying environmental parameters such as the emission cap and the allowance price in the policy structures the results indicate that decisions are sensitive to carbon prices the inventory policy could play an important role in compliance with environmental legislation although there is threshold carbon price beyond which the company must focus on strategic decisions rather than tactical decisions

just in time purchasing single or multiple sourcing abstract we consider two just in time jit purchasing models one utilizing a few sources and the other using the more conventional single source we address the issue of splitting a large order quantity into multiple deliveries taking account of the increase in the aggregate ordering transportation and inspection costs for multiple sourcing we formulate and solve a mathematical programming problem to obtain the optimal selection of suppliers and the size of the split orders for single sourcing we provide a procedure that yields the optimal number of deliveries

integrated fuzzy multi criteria decision making method and multi objective programming approach for supplier selection and order allocation in a green supply chain abstract an organization s environmental performance is affected by its suppliers environmental performance and selecting green suppliers is a strategic decision in order to be more competitive in today s global market the supplier selection problem involves several quantitative and qualitative criteria in the supplier selection process if suppliers have limited capacity or other constraints it is necessary to determine the best supplier and order quantity of each supplier in this paper we present an integrated approach of fuzzy multi attribute utility theory and multi objective programming for rating and selecting the best green suppliers according to economic and environmental criteria and then allocating the optimum order quantities among them at first the fuzzy analytic hierarchy process and fuzzy technique for order preference by similarity to ideal solution is applied in order to analyze the importance of multiple criteria by incorporating experts opinion and to determine the best green suppliers next multi objective linear programming is used to consider and to formulate various constraints such as quality control capacity and other objectives the objective of the mathematical model is simultaneously to maximize the total value of purchasing and to minimize the total cost of purchasing to handle the subjectivity of decision makers preferences fuzzy logic has been applied the efficiency and application of the proposed approach has been illustrated with a case study in an automobile manufacturing company the obtained results help firms establish a systematic approach for tackling green supplier selection and order allocation problems in a realistic situation finally managerial implications conclusions and directions for additional research are introduced

delay in payments a strategy to reduce carbon emissions from supply chains abstract the purpose of this paper is to study the effects of various scenarios of delay in payments a form of trade credit by a buyer after receiving items while including various costs such as fuel cost the costs of carbon emissions from manufacturing and transportation activities order cost and setup cost in a two echelon coordinated supply chain the model developed optimizes the environmental and economic performance of a supply chain the study presents a comparison of different scenarios through numerical examples and sensitivity analyses the main contribution of this paper is the joint consideration of delays in payments and the costs of transportation cost and carbon emissions the model has been tested with numerical examples and sensitivity analyses the findings showed that adopting delays in payments improves both environmental and economic performance of a supply chain the analyses also showed that optimizing one of the parameters from the production rate the length of delay in payments or the lot size provides the optimal solution for carbon emissions and the system cost of a supply chain this flexibility makes the model easy to use by practitioners

technology appropriation in a de growing economy this article proposes a concept of technology appropriation as a means of ideological repurposing of technology in a de growing economy its economic and institutional foundations are set forth using an endogenous theory of economic development in the spirit of marx schumpeter and veblen technological and institutional change lead interdependently to the emergence of socio technical complexes which are subject to ideological appropriation these complexes are analyzed as actor networks from an ontological perspective and exemplified using special cases in the information and communication technologies icts the approach contributes to synthesizing critical political economy with actor network theory technology appropriation is elaborated as a means of repurposing existing technologies in terms of recombination with an emphasis on the strategy of habilitation this political economic strategy delivers new insights for a solidary mode of economic reproduction in a low carbon de growing economy

modeling synergies in multi criteria supplier selection and order allocation an application to commodity trading abstract we propose a novel meta approach to support collaborative multi objective supplier selection and order allocation ssoa decisions by integrating multi criteria decision analysis and linear programming lp the proposed model accounts for suppliers performance synergy effects within a hierarchical decision structure it incorporates both heterogeneous objective data and subjective judgments of the decision makers dms representing various groups with different voting powers vps we maximize the total value of purchasing tvp by optimizing order quantity assignment to suppliers and taking into consideration their synergies encountered in different time horizons we apply the proposed model to a contractor selection and order quantity assignment problem in an agricultural commodity trading act company we maximize the strategic effectiveness of both the customers and the suppliers minimize risks increase the degree of cooperation between trading partners on all levels of supply chain integration enhance transparent knowledge sharing and aggregation and support collaborative decision making

competitive equilibria in production economies with an infinite dimensional commodity space the existence of competitive equilibrium is established for economies with a produc tion sector and an infinite dimensional space of commodities the cru cial assumptions which are required beyond those required in the fin ite dimensional setting are bounds on marginal rates of substitution and marginal rates of transformation copyright 1987 by the econometric society

from ecological macroeconomics to a theory of endogenous money for a finite planet abstract this paper takes stock of the achievements and gaps of the emerging field of ecological macroeconomics which has brought insights from specific schools of macroeconomics most notably post keynesian to ecological economics with a strong emphasis on the endogeneity of money ecological macroeconomics has proposed fiscal monetary and prudential reforms to boost green investments and developed new modeling frameworks to explore the interactions between the financial macroeconomic and biophysical spheres while these proposals open a broader range of possibilities to engage in a socio ecological transition than those offered by the current paradigm of a financialized global economy they paradoxically suffer from similar limitations by placing much faith in green investments they impose a vision of the transition that presents strong technical and institutional limitations the field also fails to revisit its own understanding of macroeconomics and of specific phenomena e g financial instability through a biophysical lens in spite of increasing transdisciplinary evidence supporting this approach we suggest overcoming these limitations through institutionalist perspectives that understand money as a language through which value is created and legitimized those perspectives seem essential to re embed the governance of money within a worldview that acknowledges the finiteness and incommensurable values of earth s life support systems

a bilinear goal programming model and a modified benders decomposition algorithm for supply chain reconfiguration and supplier selection abstract the problem addressed in this paper is related to an aerospace company seeking to change its outsourcing strategies in order to meet the expected demand increase and customer satisfaction requirements regarding delivery dates and amounts a bilinear goal programming model is developed to achieve the company s objectives a modified benders decomposition method is successfully applied to handle bilinear goal programming models in which the complicating binary variables affect the values of the deviational variables of goals attainment this influence leads to formulate the master and the sub problem as two goal programming models with different objective function decompositions as compared to the classical benders one computational experiments show that the modified benders algorithm outperforms a generic linearization method by reaching the optimal solution for larger problem with about 75 reduction in computation time

the economics of degrowth economic degrowth is ecologically desirable and possibly inevitable but under what conditions can it become socially sustainable how can we have full employment and economic stability without growth what will happen to public spending and to public debt how would production be organised in a degrowing economy and under what plausible socio political conditions could such grand changes happen standard economic theories and models ignore these questions for them economic growth is an axiomatic necessity this article reviews recent contributions in the economics of degrowth and identifies research avenues for ecological economists

multi objective models for lot sizing with supplier selection abstract in this paper two multi objective mixed integer non linear models are developed for multi period lot sizing problems involving multiple products and multiple suppliers each model is constructed on the basis of three objective functions cost quality and service level and a set of constraints the total costs consist of purchasing ordering holding and backordering and transportation costs ordering cost is seen as an ordering frequency dependent function whereas total quality and service level are seen as time dependent functions the first model represents this problem in situations where shortage is not allowed while in the second model all the demand during the stock out period is backordered considering the complexity of these models on the one hand and the ability of genetic algorithms to obtain a set of pareto optimal solutions we apply a genetic algorithm in an innovative approach to solve the models comparison results indicate that in a backordering situation buyers are better able to optimize their objectives compared to situations where there is no shortage if we take ordering frequency into account the total costs are reduced significantly

supplier selection order allocation a two stage multiple criteria dynamic programming approach this paper proposes a two stage multiple criteria dynamic programming approach for two of the most critical tasks in supply chain management namely supplier selection and order allocation in the first stage to address multiple decision criteria in supplier ranking the analytic hierarchy process ahp is employed in the second stage supplier ranks are fed into an order allocation model that aims at maximizing a utility function for the firm as well as minimizing the total supply chain costs subject to constraints on demand capacity and inventory levels a dynamic programming approach is crafted to solve the proposed bi objective model

haulage sharing approach to achieve sustainability in material purchasing new method and numerical applications abstract transportation costs are becoming increasingly important in inventory replenishment decisions and in practice lot sizing decisions are strongly affected by material handling equipment transportation flow paths vehicle capacities and technical constraints companies within a global sourcing context daily experience the cost of transportation as playing a major role in total purchasing costs on the other hand sustainability issues are always more urgent and environmental impact assessment is becoming a key requirement for materials purchasing and transportation choices this work is particularly focusing on an interesting new area of research the haulage sharing in freight transportation when sustainability considerations are taken into account the paper develops and discusses a new haulage sharing lot sizing model in which two partners are cooperating in sharing transportation paths and handling units a three step methodology based on multi objective optimization approach is here proposed to permit the complete evaluation of the costs and savings that arise with an horizontal cooperation the method is described here and applied to two different numerical cases in order to drive useful conclusions and discuss future research steps

the carbon constrained eoq model with carbon emission dependent demand abstract currently companies are looking for solutions to reduce carbon emissions associated with their operations operational adjustments such as modifications in batch sizes or order quantities have proven to be an effective way to decrease emissions in this paper a novel model is proposed that takes into account the link between an inventory policy eoq total carbon emissions and both price and environmental dependent demands in the case of an exogenous price two optimal quantities are determined which maximize a retailer s profit and which minimize carbon emissions conditions that allow a company to maximize profit while minimizing emissions and mechanisms that allow a firm to maximize its profit and to decrease its carbon emissions are determined in the case of an endogenous price some empirical results are also discussed when a firm optimizes its profit through both its selling price and its order quantity some experiments match empirical observations on the one hand an environmental strategy is more significant for cheaper and green labeled products on the other hand a public mechanism such as a carbon tax will decrease total and marginal emissions

revenue sharing coordination in reverse logistics a reverse supply chain as a post consumption activity aims at extracting value from products at the end of their life cycle it could be comprised of reusing refurbishing remanufacturing and recycling activities in this paper we revisit the issue of revenue sharing in reverse supply chains to formulate the decision problems of coordinating parties manufacturer and retailer the coordination is formed in a dynamic setting where a feedback relationship exists between the return incentive policy of the retailer and the revenue sharing incentive strategy of the manufacturer to model this process we have adopted the use of a system dynamics sd approach sd is well suited for studying the behavior of complex systems over time and where internal feedbacks and delays exist we first identify pareto optimal solutions for individual players and from environmental perspectives of landfill diversion and carbon offset we then focus on revenue sharing as a widely practiced coordination scheme in reverse supply chains it resembles a leader follower stackelberg strategic decision making game with an equilibrium solution that yields lower performance for environmental criteria in this context we investigate if how a revenue sharing mechanism can be coordinated to achieve a higher environmental performance

selection of contract suppliers under price and demand uncertainty in a dynamic market in this paper we consider a supply contracting problem in which the buyer firm faces non stationary stochastic price and demand first we derive analytical results to compare two pure strategies i periodically purchasing from the spot market and ii signing a long term contract with a single supplier the results from the pure strategies show that the selection of suppliers can be complicated by many parameters and is particularly affected by price uncertainty we then develop a stochastic dynamic programming model to incorporate mixed strategies purchasing commitments and contract cancellations computational results show that increases in price demand uncertainty favor long term short term suppliers by examining the two way interactions of contract factors price demand purchasing bounds learning and technology effect salvage values and contract cancellation both intuitive and non intuitive managerial insights in outsourcing strategies are derived

the total cost of logistics in supplier selection under conditions of multiple sourcing multiple criteria and capacity constraint abstract little attention is given in the literature to decisions on the appropriate selection of suppliers and on assigning order quantities to these suppliers in the case of multiple sourcing with multiple criteria and with suppliers capacity constraints only a few mathematical programming models to analyse such decisions have been published to date and these have tended to consider only net price as the cost of purchasing although the costs of transportation ordering and storage may be significantly important to the decision in this paper a mixed integer non linear programming model is presented to solve the multiple sourcing problem which takes into account the total cost of logistics including net price storage transportation and ordering costs buyer limitations on budget quality service etc can also be considered in the model an algorithm is proposed to solve the model and the model is illustrated using a numerical example

optimal procurement strategies for online spot markets abstract spot markets have emerged for a broad range of commodities and companies have started to use them in addition to their traditional long term procurement contracts forward contracts in comparison to forward contracts spot markets offer products at essentially negligible lead time but typically command a higher expected price for this added flexibility while also exhibiting substantial price uncertainty in our research we analyze the resulting procurement challenge and quantify the benefits of using spot markets from a supply chain perspective we develop and solve mathematical models that determine the optimal order quantity to purchase via forward contracts and the optimal quantity to purchase via spot markets we analyze the most general situation where commodities can be both bought and sold via a spot market and derive closed form results for this case we compare the obtained results to the reference scenario of pure contract sourcing and we include results for situations where the use of spot markets is restricted to either buying or selling only our approaches can be used by decision makers to determine optimal procurement strategies based on key parameters such as demand and spot price volatilities correlation between demand and spot prices and risk aversion the results of our analysis demonstrate that significant profit improvements can be achieved if a moderate fraction of the commodity demand is procured via spot markets the results also show that companies who use spot markets can offer a higher expected service level but that they might experience a higher variability in profits than companies who do not use spot markets we illustrate our analytical results with numerical examples throughout the paper

how many parts to make at once reprinted from factory the magazine of management volume 10 number 2 february 1913 pp 135 136 152 interest on capital tied up in wages material and overhead sets a maximum limit to the quantity of parts which can be profitably manufactured at one time set up costs on the job fix the minimum experience has shown one manager a way to determine the economical size of lots

vendor selection with price breaks abstract we study the problem of vendor selection where a buyer must choose order quantities to place with vendors in a multiple sourcing network the selection process is influenced by the price delivery and quality objectives of the buyer as well as by the production or rationing constraints of the vendors vendors are assumed to offer price breaks which depend on the sizes of the order quantities each proce break schedule is characterized by two attributes it represents either quantity discounts or surcharges and is either cumulative all units or noncumulative incremental we present linear and mixed binary integer programming models that provide unifying frameworks for models of vendor performance measures from the purchasing literature and models of price breaks from the operations research literature we argue that our models offer viable approaches to vendor selection with price breaks because of the availability of commercial software packages for personal computers that provide flexible and efficient computational tools for solving the models this implies that vendor selection with price breaks can be performed at the fingertips of purchasing managers

role of multiple stakeholders and the critical success factor theory for the sustainable supplier selection process abstract the concept of sustainability has become an essential theme for many industries and organisations due to a heightened sensitivity towards environmental protection and social responsibility at the same time firms still need to achieve economic viability and retain their competitive advantage because suppliers are the first entity and the initial source of any supply chain organisations should select their suppliers by a careful evaluation of their critical success factors csf achieving a successful sustainable supply chain management sscm strategy requires a firm to consider its stakeholders views based on the csf theory and by considering the multi stakeholders view in a sustainability perspective this work provides a decision support system for the sustainable supplier selection sss problem in a real world textile industry located in the emerging economy of india through a three phase methodology this study examines indian suppliers by considering the sustainability views of various stakeholders including employees customers researchers shareholders and a government environmental officer the csf priorities show that the first four influential csfs are categorized as social concerns i e maintaining long term relationships and alliances stakeholder empowerment equity labour sources and individual human rights the fifth factor is an environmental issue i e production of polluting agents among the five suppliers being evaluated in this work supplier 4 receives the top ranking specifically the results show that the supplier rankings are highly influenced by csf s social dimensions hence to validate the influence of csf s social dimensions in relation to the sss process a sensitivity analysis has been done by varying the respective weights the study concludes with the relevant managerial implications and limitations

including sustainability criteria into inventory models research on sustainability performance has considerably enriched operations management literature in recent years however work with quantitative models is still scarce this paper contributes by revisiting classical inventory methods taking sustainability concerns into account we believe that reducing all aspects of sustainable development to a single objective is not desirable we thus reformulate the classical economic order quantity model as a multiobjective problem we refer to this model as the sustainable order quantity model then a multi echelon extension of the sustainable order quantity model is studied for both models the set of efficient solutions pareto optimal solutions is analytically characterized these results are used to provide some insights about the effectiveness of different regulatory policies to control carbon emissions we also use an interactive procedure that allows the decision maker to quickly identify the best option among these solutions the proposed interactive procedure is a new combination of multi criteria decision analysis techniques

a century of evolution from harris s basic lot size model survey and research agenda abstract determining the economic lot size has always represented one of the most important issues in production planning this problem has long attracted the attention of researchers and several models have been developed to meet requirements at minimum cost in this paper we explore and discuss the evolution of these models during one hundred years of history starting from the basic model developed by harris in 1913 up to today following harris s work a number of researchers have devised extensions that incorporate additional considerations the evolution of eoq theory strongly reflects the development of industrial systems over the past century here we outline all the research areas faced in the past by conducting a holistic analysis of 219 selected journal papers and trying to give a comprehensive view of past work on the eoq problem finally a new research agenda is proposed and discussed

mean downside risk and mean variance newsvendor models implications for sustainable fashion retailing abstract newsvendor models have been well established for studying supply chain management problems with fashionable products in this paper we explore the mean downside risk mdr and mean variance mv newsvendor models under both the exogenous and endogenous retail price decision cases we first construct analytical models with the mdr and mv objectives we then show that the analytical solution schemes for both the mdr and mv problems are the same with the measures for sustainability such as the expected quantity of goods leftover the expected sales to expected goods leftover ratio the rate of return on investment and the probability of achieving a pre determined profit target we proceed to compare the levels of sustainability by the fashion retailers which employ the mean risk and the risk neutral models insights are generated

a sustainable production inventory model for a controllable carbon emissions rate under shortages abstract carbon emissions are the key factor of global warming nowadays some countries have focused on reducing carbon emission carbon tax and cap policies are the key mechanism utilized in many countries to achieve this keeping this issue in mind a sustainable economic production quantity sepq carbon tax and cap model has considered for a controllable carbon emissions rate by investing in green technology gt efforts under different with and without shortage situations this study has three models a a sustainable economic production quantity carbon tax and cap model with no shortages b a sustainable economic production quantity carbon tax and cap with partial backordering and c a sustainable economic production quantity carbon tax and cap with full backordering with and without green technology investment a solution methodology has been proposed for determining the optimal strategies of cycle time green technology investment and the fraction period length in positive inventory level several numerical examples have studied to validate the sustainable economic production quantity models the results of this paper are a sustainable economic production quantity carbon tax and cap partial backlogging case has a better justifiable profit with the highest cycle time and the lowest value of the fraction length period as well as the lower green technology investment cost compared with other models finally sensitivity analysis has provided with the managerial implication of the optimal feasible solution with respect to some key parameters

managing carbon footprints in inventory management abstract there is a broad consensus that mankind must reduce carbon emissions to mitigate global warming it is generally accepted that carbon emission trading is one of the most effective market based mechanisms to curb the amount of carbon emissions this paper investigates how firms manage carbon footprints in inventory management under the carbon emission trading mechanism we derive the optimal order quantity and analytically and numerically examine the impacts of carbon trade carbon price and carbon cap on order decisions carbon emissions and total cost we make interesting observations from the numerical examples and provide managerial insights from the analytical results

determination of paths to vendor market efficiency using parallel coordinates representation a negotiation tool for buyers abstract this study demonstrates the use of data envelopment analysis for measuring vendor performance and efficiency an algorithm by inselberg is employed for determining points of vendor efficiency on multiple criteria this study then demonstrates how parallel coordinates graphical representation can be used to display the efficiency of vendors on multiple criteria and in so doing visually identify benchmark values on these criteria for negotiating with inefficient vendors an example of a firm purchasing in a jit manufacturing environment is used to illustrate this approach the results of this approach point to its flexibility for use in vendor negotiations

newsvendor with multiple options of expediting we consider a manufacturer facing single period inventory planning problem with uncertain demand and multiple options of expediting the demand comes at a certain time in the future the manufacturer may order the product in advance with a relatively low cost she can order additional amount by expediting after the demand is realized there are a number of expediting options each of which corresponds to a certain delivery lead time and a unit procurement price the unit procurement price is decreasing over delivery lead time the selling price is also decreasing over time in this paper we assume that the manufacturer must deliver all products to the customer in a single shipment the problem can be formulated as a profit maximization problem we develop structural properties and show how the optimal solution can be identified efficiently in addition we compare our model with the classical newsvendor model and obtain a number of managerial insights

demographic structure and capital accumulation this paper develops an overlapping generations olg model to analyze the consequences of demographic structure changes induced by an exogenous shift in the birth rate we first show that a finite growth rate of the population that maximizes long run capital per capita exists then we examine the theoretical properties of this growth rate by showing that i it corresponds to the demographic structure such that the average ages of capital holders and workers are equal ii it is associated to an efficient steady state iii it increases with compulsory transfers from younger to older generations finally we explain why standard olg models do not exhibit such a growth rate

improving supply chain sustainability using exergy analysis abstract sustainable supply chain management is the improved level of management through the integration of environmental and social issues in parallel to the economic issues it has emerged as a growing subject that now receives increasing interest from practitioners and academicians limited attempts have been made to take a broader look at the overall issues that form the core topics of this type of supply chain in fact there have been many exclusive studies that investigated the impact of inadvertent or unavoidable costs of supply chain processes exergy analysis is a powerful thermodynamic tool that may be employed to analyze and identify the inefficiencies in a process or a system it has also been extended to efficiently evaluate how sustainable an industrial system process or product is this paper introduces exergetic models that compute and compare the consumed exergy for two coordination policies it also evaluates the consumed exergy when producing ordering locally versus globally it recognizes the importance of financial social and environmental aspects of choosing the more sustainable destination to produce and distribute a product numerical examples are presented and discussed to provide some insights for managers and decision makers to select between domestic policies based on the consumed exergy and the monetary cost results show that societies can gain more from less consumed exergy and firms can save on some costs when producing ordering domestically this paper recommends to governments and other stakeholders to take actions that are effective in making societies consume resources wisely

on the existence of price equilibria in dynamic economies abstract i extend mckenzie s general characterization of the existence of competitive equilibria in static finite horizon models to a class of dynamic infinite horizon economies that subsumes overlapping generations as a special case with a few necessary exceptions the assumptions employed in my existence proof are natural extensions of mckenzie s in particular i strengthen the existing literature by imposing mckenzie type irreducibility only on the whole economy and not on certain artificial sub economies and by imposing mckenzie s weak continuity and convexity conditions i also establish the general existence of equilibria with nominal government surplus

trends in inventory management abstract inventory management is one of the success stories of recent years and it is changing rapidly in response to international competition and new technology this paper examines some of these developments inventory is a major investment in most companies it strongly influences the internal flexibility of a company e g by allowing production levels to change easily and by providing good delivery performance to customers yet inventory ties up working capital and space and it can suffer from obsolescence deterioration and shrinkage it can also add to administrative complexity in recent years attention in manufacturing industry has concentrated on an inventory is waste philosophy using jit production usually accompanied by visible pull or consumer demand driven systems the approach is also very effective in supermarket retailing and at its best provides very high stock turn and high profits to the company at the same time as providing good service and fresh items to customers at low cost current changes in inventory management consider the total logistics chain under the term logistics management place a greater emphasis on purchasing rather than producing in house and use more international sourcing changes to recording methods include the use of different methods of information collection and processing e g bar coding in retailing and manufacture and electronic exchange of information control methods are more computer based and are becoming part of increasingly integrated systems there are some obvious problems still to be solved procedures are needed to bring one off analyses of inventory to become part of routine systems work needs to be done to produce performance measures which are consistent between different levels of the organisation and the modelling of dynamic performance needs to become part of the design of our production inventory systems more fundamentally we still do not know how to classify companies let alone how to determine the best approach to inventory planning and control for a particular kind of company

the ecology of money a critical assessment abstract this paper assesses the proposal to transform the monetary system into an ecology of money that is into a system made of a large diversity of complementary currencies its central aim is to examine whether this proposal could provide a systemic solution to both the ecological and financial crises as several authors most notably lietaer and douthwaite have argued to this end it analyses the two main arguments in favour of this proposal first it focuses on the claim that an ecology of money would be more resilient and less prone to crisis than the present monetary system it shows that this argument suffers from several conceptual flaws and argues that it fails to provide sufficient normative reasons to favour an ecology of money second this paper analyses the claim that an ecology of money could help defeat the monetary growth imperative that supposedly plagues our economies the paper raises serious doubts about the existence of such an imperative and questions the claim that an ecology of money could contribute to weaken it in a significant way

environmentally responsible inventory models non classical models for a non classical era abstract mathematical models of inventory typically include the three inventory associated costs of surplus shortage and ordering these classic inventory models are then analysed so as to choose inventory parameters that usually minimise the total cost of operating the inventory system being investigated unfortunately classic inventory models do not provide a meaningful basis for analysing many real and increasingly important practical inventory problems and situations it is therefore not surprising that over recent years several authors have discussed these issues in broad terms and suggested that a new paradigm needs to be developed this paper develops some specific aspects of this discussion in particular the paper identifies a range of inventory problems that are not covered appropriately by traditional inventory analysis one of these is to design responsible inventory systems i e systems that reflect the needs of the environment the paper then examines the importance of inventory planning to the environment in greater detail for example packaging is important not only because of its costs and the protection that it provides to the inventory items but also because of its eventual effects on the environment in terms of the use of resources and potential landfill for similar reasons waste which can result from poor inventory management is highly important the location of stores is important because location affects transport costs thus the influence of the secondary aspects of most inventory models packaging waste and location are important but even more important are the inter relations with the total system in particular the location of the manufacturing plants and the effect that inventory planning has on the logistics chain potentially have considerable environmental implications inventory is part of a wider system however until the cost charged for an activity reflects the true environmental cost of that activity it is likely that decisions will be made on the basis of erroneous data in that situation we are faced with either determining the environmental cost of specific actions or to use environmental costs that are somewhat contrived in which case it may be more sensible to use very different performance measures and models the paper discusses these ideas and ways in which inventory policies may reassure us with our environmental concerns

a theory of commodity price fluctuations this paper studies the price fluctuations of storable commodities that are traded in open markets and are subject to random shocks to demand or more particularly to supply it relaxes the common assumption that the shocks are identically and independently distributed in favor of temporally dependent and periodic disturbances the existence of a unique stationary rational expectations equilibrium is demonstrated for each of the models analyzed and testable implications of the models are derived an illustrative empirical investigation is then undertaken for the model with periodic disturbances using monthly time series observations for seven commodities over the period 1960 93

the economic order quantity model revisited an extended exergy accounting approach abstract the economic order quantity eoq model has been popular among academicians and practitioners for decades despite the many variants of the eoq that have appeared in the literature to fine tune it to reality it still has limitations a major one is that it does not take into account the hidden costs inherent in inventory systems some of these costs relate to sustainability issues including environmental social labor and economic effects this paper considers some of these costs referred to as the exergetic costs and estimates them using the extended exergy accounting eea approach extended exergy accounting assigns equivalent exergetic values to capital labor and environmental remediation costs of a system the analysis combines the classical exergy analysis with the sustainability factors which are the labor capital and environment the paper uses an exergetic model to determine the eoq inventory policies for three firms operating in the usa germany and china the results show that the eoq is different for the three firms because the equivalent exergy of capital labor and environment remediation costs is different in each country

modeling of biomass to energy supply chain operations applications challenges and research directions reducing dependency on fossil fuels and mitigating their environmental impacts are among the most promising aspects of utilizing renewable energy sources the availability of various biomass resources has made it an appealing source of renewable energy given the variability of supply and sources of biomass supply chains play an important role in the efficient provisioning of biomass resources for energy production this paper provides a comprehensive review and classification of the excising literature in modeling of biomass supply chain operations while linking them to the wider strategic challenges and issues with the design planning and management of biomass supply chains on that basis we will present an analysis of the existing gaps and the potential future directions for research in modeling of biomass supply chain operations

competition and cooperation between supply chains in multi objective petroleum green supply chain a game theoretic approach petroleum supply chain is one of the most important and sophisticated managing missions in both developing and developed countries nowadays environmental pollution is another critical factor in designing the petroleum supply chain this importance encourages the governments to minimize the amount of environmental pollution and maximize their obtained profit simultaneously by enacting required legislations on the transportation modes and the refineries considering maximizing the job creation and each stakeholder s profit and minimizing the emission of co2 and other greenhouse gases at the same time is called sustainable petroleum supply chain which has been paid little attention despite its significance therefore the modelling of petroleum supply chain considering sustainability and pricing issues is investigated for the first time in this work and a sustainable competitive petroleum supply chain scpsc model is developed to minimize pollution while maximizing the profits and job creation this problem is a two level model the first level in scpsc is the competition between the supply chains of the government and the private sectors which is modelled by the game theory approach including nash and stackelberg equilibria the optimal price and demand for each supply chain determined in the first level are considered as the second level parameters in the second level the optimal values of the decisions in designing the petroleum supply chain will be obtained by solving mixed integer linear programming milp under the mentioned three objective functions finally the proposed model is applied to a real world case in the national iranian oil company nioc based on the results of the stackelberg equilibrium the government profits increase by 11 12 while that of the private sector decreases by 25 4 and 28 11 increasing in the government profit is due to increased demand provided by government the results show that the whole profit of the petroleum supply chain in nash equilibrium is 9 8 more than that in the stackelberg equilibrium

ecological monetary economics a post keynesian critique the monetary analysis of some ecological economists currently appears to be mostly articulated around the following core a stationary economy and a fortiori a degrowth economy is incompatible with a system in which money is created as interest bearing debt to question the relevance of the debt money positive interest rate output growth nexus this paper adopts a critical stance towards the currently emerging ecological monetary economics from the standpoint of another strand of heterodox economics the post keynesian approach in its current state ecological monetary economics is at odds with post keynesian economics in its analysis of the money growth relationship this will be shown using the theory of endogenous money and a simple cambridgian kaleckian model where debt money and a positive interest rate are compatible with a full stationary economy

the euthanasia of the rentier a way toward a steady state economy abstract a positive interest rate has many impacts on ecology one of them is the pushing of economic growth in the present economy accumulation of capital is an end in itself according to the golden rule of accumulation the extension rate of the capital stock is equal to the interest rate however in the present economic conditions the interest rate is always significantly higher than zero due to the liquidity premium of money keynes in this context old proposals such as the free money approach of silvio gesell could provide interesting solutions gesell wanted to neutralize the liquidity premium by putting artificial carrying costs on money by increasing the stock of capital assets without being interrupted by economic crises the interest and profitability level should be reduced down to zero because in this situation every marginal saving and marginal investment would cause a negative interest or profitability rate they would be stopped though keynes was very excited by the proposals of gesell he criticized the fact that gesell did not see many of the further obstacles however these obstacles could be overcome by means of further institutional reforms

developing an input output activity matrix ioam for environmental and economic analysis of manufacturing systems and logistics chains abstract an activity matrix am shows the activities that transform an organization s inputs into outputs the inputs are the system targets and the materials energy and other resources that are used to achieve these the outputs are the system performance expressed in terms of production quality profit environmental performance waste etc performance may be measured against the financial environmental technical social or other system targets a concurrent enterprise view is used to represent the manufacturing system activities and the paper examines how an am may be used to represent and design systems two kinds of am are examined an unconstrained activity matrix and an input output activity matrix ioam with an unconstrained am the system designer chooses system outputs attributes or requirements intuitively this provides great flexibility and allows e g the social and organisational implications of proposed changes to be investigated the inputs are not formally stated although a systems designer normally focuses on identifying the stages of a product life cycle and analysing their impact on the system s outputs the main emphasis of the paper is on the ioam and its use to represent the transformation of an organization s inputs into outputs the input output representation developed in the paper is used to examine manufacturing and logistics systems first the ioam is used to represent a manufacturing system as one tier of a logistics chain and its performance secondly the ioam representations may be derived for a multi tier system to represent its production economic and environmental performance

equilibrium for overlapping generations in continuous time abstract we prove the existence of general equilibrium for continuous time overlapping generations models previous theorems exclude all non linear c e s and von neumann morgenstern preferences and exclude production our primitive assumptions are satisfied by such preferences and by all markovian production technologies satisfying bewley s assumptions for arrow debreu models provided that storage is possible at some finite rate of depreciation and some positive capacity a non existence example shows our markovian and storage assumptions cannot be dropped journal of economic literature classification numbers c62 d51 d90

the development and structure of financial systems abstract firms raise external finance via monitored bank loans and non monitored borrowing in a dynamic general equilibrium model access to credit and each type of financing depend on the wealth distribution due to moral hazard we study the depth of credit markets financial development and conditions under which the financial system relies more on either type of external finance financial structure initial inequality investment size and institutional factors determine the level of financial development while financial structure is shaped by the investment technology and legal and financial institutions the model s predictions are consistent with historical and recent development experience

sustainable trade credit and replenishment decisions with credit linked demand under carbon emission constraints abstract in this paper we consider issues of sustainability in the context of joint trade credit and inventory management in which the demand depends on the length of the credit period offered by the retailer to its customers we quantify the impacts of the credit period and environmental regulations on the inventory model starting with some mild assumptions we first analyze the model with generalized demand and default risk rates under the carbon cap and trade policy and then we make some extensions to the model with the carbon offset policy we further analytically examine the effects of carbon emission parameters on the retailer s trade credit and replenishment strategies finally a couple of numerical examples and sensitivity analysis are given to illustrate the features of the proposed model which is followed by concluding remarks

dynamic version of the economic lot size model this article originally appeared in management science october 1958 volume 5 number 1 pp 89 96 published by the institute of management sciences a forward algorithm for a solution to the following dynamic version of the economic lot size model is given allowing the possibility of demands for a single item inventory holding charges and setup costs to vary over n periods we desire a minimum total cost inventory management scheme which satisfies known demand in every period disjoint planning horizons are shown to be possible which eliminate the necessity of having data for the full n periods

stock flow consistent macroeconomic models a survey the stock flow consistent sfc modelling approach grounded in the pioneering work of wynne godley and james tobin in the 1970s has been adopted by a growing number of researchers in macroeconomics especially after the publication of monetary economics by godley and lavoie which provided a general framework for the analysis of whole economic systems and the recognition that macroeconomic models integrating real markets with flow of funds analysis had been particularly successful in predicting the great recession of 2007 2009 we introduce the general features of the sfc approach for a closed economy showing how the core model has been extended to address issues such as financialization and income distribution we next discuss the implications of the approach for models of open economies and compare the methodologies adopted in developing sfc empirical models for whole countries we review the contributions where the sfc approach is being adopted as the macroeconomic closure of microeconomic agent based models and how the sfc approach is at the core of new research in ecological macroeconomics finally we discuss the appropriateness of the name sfc for the class of models we survey

the single period inventory model under dual sourcing and product carbon footprint constraint abstract important drivers for environmental sustainability efforts in purchasing and supply management are top management initiatives and compliance with laws and regulations on the other hand market forces are largely ignored although it is shown that the product carbon footprint contained on the product s eco label influences the purchasing decisions of consumers if it is disclosed by several companies in an industry then the product carbon footprint turns out to be a relevant competitive differentiator i e the company with lower emissions can increase its market share in this paper we consider the single period inventory model with product carbon footprint constraint an upper bound for the carbon footprint is specified as a benchmark derived either from the company s environmental target or from an industry standard in the case of one supply option the optimal order quantity is characterized by a one sided control limit policy especially for high profit products the environmental constraint is binding thus has a negative impact on the economic performance i e expected profit if a second supply option exists in the resulting dual sourcing framework with quick response two scenarios with different additional costs and emissions for the second emergency order are considered in the first scenario for both options the same supplier is used it applies to an offshore supplier because a fast transportation mode is considered here the structure of the optimal first order quantity is a two sided control limit policy in scenario two the second order comes from a different onshore supplier by comparing the fast and the onshore scenario the trade off between economic expected profit and environmental expected emissions performances is discussed

does credit create a growth imperative a quasi stationary economy with interest bearing debt abstract this paper addresses the question of whether a capitalist economy can ever sustain a stationary or non growing state or whether as often claimed capitalism has an inherent growth imperative arising from the charging of interest on debt we outline the development of a dedicated system dynamics macro economic model for describing financial assets and liabilities in a stock flow consistent framework falstaff and use this model to explore the potential for stationary state outcomes in an economy with balanced trade credit creation by banks and private equity contrary to claims in the literature we find that neither credit creation nor the charging of interest on debt creates a growth imperative in and of themselves this finding remains true even when capital adequacy and liquidity requirements are imposed on banks we test the robustness of our results in the face of random variations and one off shocks we show further that it is possible to move from a growth path towards a stationary state without either crashing the economy or dismantling the system nonetheless there remain several good reasons to support the reform of the monetary system our model also supports critiques of austerity and underlines the value of countercyclical spending by government

analyzing the impacts of carbon regulatory mechanisms on supplier and mode selection decisions an application to a biofuel supply chain this paper analyzes the impacts of carbon regulatory mechanisms on replenishment decisions in a biofuel supply chain we employ mathematical models for operations which integrate replenishment and supplier transportation mode selection decisions these models explicitly account for carbon emissions that may result from transportation and inventory storage activities this research is motivated by observations indicating that nearly 19 of the energy consumption and 25 of the energy related carbon dioxide emissions worldwide arise from transportation because freight transportation is expected to continue to grow we consider the impacts of different carbon regulatory mechanisms on transportation and inventory replenishment decisions in a biofuel supply chain a set of extensive numerical experiments uses the biofuel supply chain context to analyze the impacts of different regulatory mechanisms including carbon cap carbon tax carbon cap and trade and carbon offset on performance we use existing methodologies to calculate emissions as a function of distance traveled load weight and transportation mode used we also use publicly available data to derive representative biomass transportation costs as a consequence our numerical results are meaningful and give a realistic representation of the relationships between emissions from different transportation modes and the resulting costs the results of our computational experiments indicate that carbon regulatory mechanisms have a non trivial impact on replenishment schedules and as a consequence costs and emissions in the supply chain

integrated economic and environmental models for a multi stage cold supply chain under carbon tax regulation abstract the elevated level of public and organizations awareness concerning sustainability has necessitated the adoption of environmentally conscious practices in the management of supply chains as such classical inventory models wherein the sole measure of performance is cost minimization are no longer appropriate to handle such emerging and pressing issue this paper assesses the impact of accounting for carbon emissions resulting from transportation and storage activities of a cold item in the context of a multi stage supply chain comprised of a plant warehouse a distribution center dc and a retailer we present an operational cost minimization model a carbon footprint minimization model and a hybrid economic and environmental minimization model where all models seek to determine the optimal lot sizing and shipping quantities alongside the number of trucks to be used in the upstream and downstream directions of the supply chain as well as the number of freezer units utilized at the dc which is owned by a third party logistics provider the structural properties for the optimal solution of the three models are identified and solution algorithms are also proposed upon conducting computational experiments it turns out that the incorporation of carbon related costs through carbon tax regulation may call for adjusting the adopted operational policy which results in a minor increase in the operational cost however this increase is outweighed by the savings resulting from the carbon related costs numerical results of the sensitivity analysis on the carbon tax policy indicate that as the tax rate increases substantial reductions in the amount of carbon footprint emitted are realized and cost savings are also achieved when adopting the lot sizing and shipping policy of the third integrated model over the operational cost minimization model

a weighted max min model for fuzzy multi objective supplier selection in a supply chain abstract supplier selection is one of the most important activities of purchasing departments this importance is increased even more by new strategies in a supply chain supplier selection is a multi criteria decision making problem in which criteria have different relative importance in practice for supplier selection problems many input information are not known precisely the fuzzy set theories can be employed due to the presence of vagueness and imprecision of information a weighted max min fuzzy model is developed to handle effectively the vagueness of input data and different weights of criteria in this problem due to this model the achievement level of objective functions matches the relative importance of the objective functions in this paper an analytic hierarchy process ahp is used to determine the weights of criteria the proposed model can help the decision maker dm to find out the appropriate order to each supplier and allows the purchasing manager s to manage supply chain performance on cost quality and service the model is explained by an illustrative example