comments on the eoq model for deteriorating items with conditional trade credit linked to order quantity in the supply chain management abstract ouyang et al 2009 consider an economic order quantity eoq model for deteriorating items with a partially permissible delay in payments linked to order quantity basically their inventory model is practical but there are some defects from the logical viewpoints of mathematics in this paper the functional behaviors of the annual total relevant costs are explored by rigorous methods of mathematics a complete solution procedure is also developed to make up for the shortcomings of ouyang et al 2009 in numerical examples it is proved that the new solution procedure could avoid making wrong decisions and causing cost penalties

inventory and credit decisions for time varying deteriorating items with up stream and down stream trade credit financing by discounted cash flow analysis abstract in today s competitive markets most firms in united kingdom and united states offer their products on trade credit to stimulate sales and reduce inventory trade credit is calculated based on time value of money on the purchase cost i e discounted cash flow analysis recently many researchers use discounted cash flow analysis only on the purchase cost but not on the revenue which is significantly larger than the purchase cost and the other costs for a sound and rigorous analysis we should use discounted cash flow analysis on revenue and costs in addition expiration date for a deteriorating item e g bread milk and meat is an important factor in consumer s purchase decision however little attention has been paid to the effect of expiration date hence in this paper we establish a supplier retailer customer supply chain model in which a the retailer receives an up stream trade credit from the supplier while grants a down stream trade credit to customers b the deterioration rate is non decreasing over time and near 100 percent particularly close to its expiration date and c discounted cash flow analysis is adopted for calculating all relevant factors revenue and costs the proposed model is an extension of more than 20 previous papers we then demonstrate that the retailer s optimal credit period and cycle time not only exist but also are unique thus the search of the optimal solution reduces to a local one finally we run several numerical examples to illustrate the problem and gain managerial insights

understanding innovation an analysis of persistence for spanish manufacturing firms abstract this study focuses on the persistence of innovation in a panel of spanish manufacturing firms for the period 1990 2008 in particular we analyse whether persistence in firms innovation activities over time is the result of previous experience the dynamic capabilities of the firm or industry market related characteristics we find that r d input and innovation output are highly persistent at the firm level after controlling for unobserved heterogeneity and initial conditions and by using a dynamic random effects probit we conclude that there are similar determinants of persistence in r d and innovative activities among external environmental factors market dynamism affects r d and innovation regarding firm specific characteristics size and outsourcing also have a positive impact on both processes past innovative behaviour is clearly more decisive in explaining the current state of r d and innovation activities than external factors or firm level heterogeneity

on r d timing under uncertainty abstract in this paper we analyze the problem of endogenous r d timing when technological breakthrough and innovation are random events in a dynamic framework which involves the substitution of an exhaustible resource oil for instance by an alternative technology the backstop that provides an everlasting source of energy under fairly general assumptions we characterize the pattern of exploitation of both energy sources and study the effect of uncertain technological breakthrough on the r d timing decision on resource prices and on the pattern of resource use in comparison to the certainty case it is shown that uncertainty consideration might delay the undertaking of r d and might lead to a more rapid resource depletion pattern for a considerable range of r d capital costs while the opposite result the conventional wisdom holds only for some other range

unilateral climate policy and the green paradox extraction costs matter i analyze the effect of unilateral climate policies in a two country model where fossil fuel extraction costs depend on both current extraction and remaining stock and where a constant marginal cost clean substitute is available an intensification of climate policy in the country with an initially stricter policy does not increase early fossil fuel extraction i e there is no weak green paradox or the present value of pollution costs i e there is no strong green paradox if energy demand in that country is initially met with a mix of fossil fuel and a substitute whether a stricter climate policy in the country with an initially laxer policy causes a weak green paradox depends on the price elasticity of energy demand and the strength of the flow and stock dependence of extraction costs if the reduction of total extraction is sufficiently strong it overcompensates for a weak green paradox with respect to pollution costs thus a weak green paradox does not necessarily imply a strong green paradox due to stock dependence politique climatique unilaterale et paradoxe vert l incidence des couts d extraction l article analyse l effet des politiques climatiques unilaterales dans un modele a deux pays ou les couts d extraction de combustibles fossiles dependent a la fois de l extraction actuelle et du stock residuel et ou la disponibilite d un substitut energetique propre et constant a cout marginal demeure une intensification des politiques climatiques dans le pays de pair avec une politique initialement plus stricte n augmente ni l extraction precoce des combustibles fossiles c est a dire qu il n y a pas de paradoxe vert faible ni la valeur actuelles des couts de pollution c est a dire qu il n y a pas de paradoxe vert accru x00ab pour autant que la demande en energie dans ce pays est initialement satisfaite par une combinaison d un combustible fossile et d un substitut qu une politique climatique plus stricte dans ce pays dote d une politique initialement plus laxiste entrane un paradoxe vert moins prononce depend de l elasticite par rapport au prix de la demande d energie de l importance du flux et de la dependance en matiere de stock relativement aux couts d extraction si une reduction de l extraction totale est suffisamment forte elle surcompensera un paradoxe vert limite relativement aux couts de pollution ainsi un faible paradoxe vert n engendre pas necessairement un fort paradoxe vert en raison de la dependance au stock

a review of trade credit literature opportunities for research in operations abstract trade credit arises when a buyer delays payment for purchased goods or services its nature has predominantly been an area of inquiry for researchers from the disciplines of finance marketing and economics but it has received relatively little attention in other domains in our article we provide an integrative review of the existing literature and discuss conflicting study outcomes we organize the relevant literature into seven areas of inquiry and analyze four in detail trade credit motives order quantity decisions credit term decisions and settlement period decisions additionally we derive a detailed agenda for future research in these areas

a note on optimal replenishment policies for non instantaneous deteriorating items with price and stock sensitive demand under permissible delay in payment abstract soni 2013 int j prod econ 146 1 259 268 proposed optimal replenishment policies for non instantaneous deteriorating items i e the product starts deteriorating after a period of no deterioration with price and stock sensitive demand with a stock dependent demand it is desirable to have non zero ending inventory due to potential profit resulting from the increased demand however soni 2013 int j prod econ 146 1 259 268 treated those ending inventory as fresh stocks to go through another period of non deterioration again additionally he assumed for simplicity that the replenishment cycle time t must be longer than the period of non deterioration t d i e t t d in reality one should consider all possible replenishment cycle time to maximize the profit in this note we complement the shortcomings of his model by i selling those ending inventory as salvages and ii considering all possible replenishment cycle time which may be shorter than the period of non deterioration with these modifications the repeatability of the replenishment cycle is ensured and the applicability of soni s model is strengthened the numerical examples indicate that the global optimal solution is indeed possible in the case of t t d

energy transition towards economic and environmental sustainability feasible paths and policy implications this paper focuses on growth feasibility in an era of increasing scarcity of fossil fuels a stylised dynamic model illustrates the implications of investing in smooth technological progress in the field of renewable energy positive rates of gdp growth sustained by fossil fuels entail on the one hand more income available for r d in renewable energy sources and on the other an acceleration of the exhaustible resource depletion time our model explores such a trade off and highlights the danger of high growth rates policies should target low growth rates stimulate investment in alternative energy sources and discourage consumption growth

an eoq model with partial backordering and advance payments for an evaporating item abstract in the classic economic order quantity model the purchasing cost of an order is paid at the time of its receipt in some cases retailers ask purchasers to pay all or a fraction of the purchasing cost in advance and may allow them to divide the prepayment into several equal sized parts in this paper an economic order quantity model for an evaporating item with partial backordering and partial consecutive prepayments is developed with a real case study of a gasoline station real numerical examples illustrate the proposed model and the solution method

carbon taxation opec and the end of oil abstract i develop a differential game between an oil cartel and an importer investing in research and development r d to reduce the cost of a green substitute to oil in equilibrium the cartel is forced to deter the substitute which thus imposes a price ceiling falling over time credible carbon taxes are below the pigovian level implying the importer cannot internalise the full pollution externality much less capture resource rents without carbon pricing the importer curtails long run pollution using a costly r d programme normatively climate policy will be more expensive if relying on green r d programmes only

optimal transition to backstop substitutes for nonrenewable resources abstract we analyze the optimal transition from a primary nonrenewable resource to a backstop substitute for a class of problems characterized by the property that the backstop cost decreases continuously as learning from r d efforts accumulates to increase the knowledge base the transition policy consists of the r d process and of the time profiles of the primary and backstop resource supply rates we find that the optimal r d process follows a most rapid approach path mrap the knowledge process associated with r d should approach some endogenously derived target process as rapidly as possible and proceed along it thereafter thus if the initial knowledge level is sufficiently low and the cost structure justifies r d activities the r d efforts should be initiated without delay at the highest affordable rate and slow down later on this pattern contrasts previous findings that typically recommend a single humped r d process with a possible initial delay

integrating deterioration and lifetime constraints in production and supply chain planning a survey abstract items with short lifetimes that are subject to deterioration are important in the business world research has a long tradition in integrating deterioration and value loss effects into mathematical models for inventory planning and control where such effects are understood as a general loss or shrinkage of inventory however there has been little work in the modeling of lifetime restrictions of items to prevent wastage and disposals especially in a dynamic planning context globalization and other trends extend the consideration of single companies to whole supply chains implying increased coordination and information needs this is important as planning decisions impact lead times and thus the quality of items in the whole supply chain products that exceed their useful lifetime can impose high costs due to inventory loss or the need to rework them this implies increased utilization of scarce resources e g machine time metals and or energy thereby increasing co 2 levels we survey the state of the art regarding depreciation effects and the modeling of lifetime constraints as well as a classification of models following business planning functions of the value chain a critical evaluation of approaches and their limitations is provided highlighting directions for future research

inventory models with ramp type demand rate partial backlogging and weibull deterioration rate in this paper an inventory model with general ramp type demand rate time dependent weibull deterioration rate and partial backlogging of unsatisfied demand is considered the model is studied under the following different replenishment policies a starting with no shortages and b starting with shortages the model is fairly general as the demand rate up to the time point of its stabilization is a general function of time the backlogging rate is any non increasing function of the waiting time up to the next replenishment the optimal replenishment policy for the model is derived for both the above mentioned policies

is there really a green paradox abstract in the absence of a co2 tax the anticipation of a cheaper renewable backstop increases current emissions of co2 since the date at which renewables are phased in is brought forward and more generally future emissions of co2 will decrease the effect on global warming is unclear green welfare falls if the backstop is relatively expensive and full exhaustion of fossil fuels is optimal but may increase if the backstop is sufficiently cheap relative to the cost of extracting the last drop of fossil fuels plus marginal global warming damages as then it is attractive to leave more fossil fuels unexploited and thus limit co2 emissions we establish these results by analyzing depletion of non renewable fossil fuels followed by a switch to a clean renewable backstop paying attention to timing of the switch and the amount of fossil fuels remaining unexploited we also discuss the potential for limit pricing when the non renewable resource is owned by a monopolist finally we show that if backstops are already used and more backstops become economically viable as the price of fossil fuels rises a lower cost of the backstop will either postpone fossil fuel exhaustion or leave more fossil fuel in situ thus boosting green welfare however if a market economy does not internalize global warming externalities and renewables have not kicked in yet full exhaustion of fossil fuel will occur in finite time and a backstop subsidy always curbs green welfare

innovative capacity of italian manufacturing firms in the current scenario of h igh technological co mpetitiveness and environmental co mp lexity the innovation capacity of manufacturing firms is one of the principal key driver for co mpeting on the global markets the context is increasingly dominated by strong and growing competition between companies fro m all over the world so manufacturing firms are forced to move the focus of competitive advantage on innovation this paper focuses on innovative capacity of italian manufacturing firms over the period 2007 2009 fro m three different points of view first the investments in technological equipment plant machinery and ict second the rd third the way that firms finance their innovation activity and investments analyzing a samp le of 524 euro pean manufacturing firms fro m these three different points of view several findings emerge fro m the co mparison of firms in different countries most italian co mpanies have a good basic ict supply but they invest relatively less than the average in new in frastructure mach inery and equip ment investments in innovation and r d are stronger although funding strategies are unbalanced towards traditional debt instruments and they are more undifferentiated considering the final ob jectives of the investment the research concludes with interesting managerial implications wh ich provide a conceptual interpretation of the phenomena and prescribe actions to policy makers

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

celebrating a century of the economic order quantity model in honor of ford whitman harris abstract this writing presents a brief introduction to the papers included in the special issue celebrating a century of the economic order quantity model in honor of ford whitman harris published by the international journal of production economics forty one papers covering an extensive scope of inventory management have been incorporated in this volume from contributing authors from 20 countries located in america asia europe and africa this special issue also provides a basis for new directions in inventory management research

optimal order quantity and selling price over a product life cycle with deterioration rate linked to expiration date it is evident that the lower the price the higher the demand therefore price is an important factor in a consumer s purchasing decision additionally for today s health conscious consumers product freshness is another important factor in purchasing decisions since product freshness declines over time today s health conscious consumers prefer a perishable product with a longer sell by date to a shorter one moreover a product s demand rate moving through its life cycle can be approximately represented by a trapezoid type pattern which includes constant demand increasing demand and decreasing demand as special cases in existing literature several researchers have developed inventory models for trapezoidal demand however they failed to consider pricing strategy product freshness linked to expiration date and purchasing cost in this study we enhance previous models by 1 taking pricing into consideration 2 exploring deterioration rate linked to expiration date and 3 adding an appropriate non constant purchasing cost we then derive theoretical results and run numerical examples to obtain managerial insights for instance the total profit without purchasing cost is significantly lower than that with purchasing cost included also if the cost of lost sales is improperly low then the total profit may become negative due to a large amount of lost sales

scarcity growth and r d abstract the limits to economic growth due to resource scarcity can be alleviated only by the development of backstop substitutes this paper combines resource based economic growth with r d to reduce the cost of backstop technologies characterizing the entire dynamics of optimal growth and r d processes we find that an economy s growth prospects depend on its type as determined by its production technology and learning ability and by its knowledge capital endowment a wide variety of growth patterns emerges ranging from cases in which an economy that without r d eventually stagnates converges to a steady state is diverted by r d onto a path of sustained growth to cases in which r d is not warranted resource scarcity is shown to encourage r d due to the increased reliance on the backstop technology

technology ladders and r d in dynamic cournot markets abstract motivated by dramatic and unpredictable technological advances in energy production for instance drilling and extraction of shale oil we extend cournot models of competition to incorporate research and development rd for example the potential of future monopoly can spur r d investment now even if the firm is presently uncompetitive and not actively producing we also show that surprisingly random innovations have an ambiguous effect on r d this feature which is driven by the cournot framework contrasts with the common situation whereby uncertainty lowers innovation and delays r d investments finally we demonstrate that increased competition may actually increase efforts to innovate through higher desire to achieve dominance this would match the anecdotal evidence that the threat of market entrants forces incumbents to maintain high r d

retailer s economic order quantity when the supplier offers conditionally permissible delay in payments link to order quantity abstract trade credit financing is increasingly recognized as an important strategy to increase profitability in inventory management we revisit an economic order quantity model under conditionally permissible delay in payments in which the supplier offers the retailer a fully permissible delay of m periods i e there is no interest charge until m if the retailer orders more than or equal to a predetermined quantity w however if the retailer s order quantity is less than w then the retailer must make a partial payment to the supplier and enjoy a permissible delay of m periods for the remaining balance in this paper we extend the mentioned eoq under conditionally permissible delay in payments to complement some shortcomings of the model by contrast to the differential calculus method we propose a simple arithmetic geometric method to solve the problem furthermore we establish some discrimination terms to identify the unique optimal solution among three alternatives and explain those theoretical results by simply economical interpretations finally we solve several numerical examples to illustrate the theoretical results and obtain some managerial implications

economic production quantity models for deteriorating items with up stream full trade credit and down stream partial trade credit abstract in practice in order to reduce default risks with credit risk customers a seller e g a manufacturer or a retailer frequently requests its credit risk customers to pay a fraction of the purchase amount at the time of placing an order as collateral deposit and then grants a permissible delay on the outstanding balance i e a down stream partial trade credit by contrast the seller usually receives a permissible delay on the entire purchase amount from the supplier i e an up stream full trade credit in this paper we propose an economic production quantity epq model for deteriorating items in a supply chain with both up stream and down stream trade credit financing by using fractional programming results we can prove that the optimal solution not only exists but also is unique moreover we propose three discrimination terms to identify the optimal solution among possible alternatives finally some numerical examples are presented to highlight the theoretical results and managerial insights

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

a martingale characterization of the price of a nonrenewable resource with decisions involving uncertainty abstract this paper presents a general model of nonrenewable resource consumption and exploration decisions involving uncertainty about the time of occurrence of an event such as exhaustion stock discovery or a substitute development the resulting price process is characterized in terms of necessary and sufficient conditions under which the price is expected to rise at a rate equal to greater than or less than the discount rate the general model is illustrated and the price process and the optimal decisions are characterized by examining the three types of uncertainty indicated above

inventory models for deteriorating items with maximum lifetime under downstream partial trade credits to credit risk customers by discounted cash flow analysis abstract getting loans from banks are almost impossible after 2008 global financial crisis as a result about 80 of companies in united kingdom and united states offer their products on various short term free interest loans i e trade credit to customers numerous researchers and academicians apply discounted cash flow dcf analysis merely to compute the interest earned and charged during the credit period but not to the revenue and other costs which are considerably larger than the interest earned and charged for a rigorous analysis the dcf on all relevant costs is applied in addition many products deteriorate continuously and cannot be sold after their maximum lifetimes or expiration dates however very few researchers and investigators have implemented the product lifetime expectance into their models in this paper a supplier retailer customer chain system is developed in which the retailer gets an upstream full trade credit from the supplier whereas offers a downstream partial trade credit to credit risk customers the deterioration rate is non decreasing over time and near 100 particularly close to its expiration date and dcf analysis is applied to compute all relevant costs this paper demonstrates that the retailer s optimal replenishment cycle time not only exists but also is unique thus the search of the global optimal reduces to finding a local solution finally several numerical examples and sensitivity analysis are performed in order to illustrate the problem and obtain managerial insights

accounting for global warming risks resource management under event uncertainty abstract optimal management of atmospheric pollution is discussed with a special emphasis on the uncertainty concerning the occurrence of undesirable events associated with the greenhouse effect the uncertainty considered here stems from our ignorance of the exact pollution level required to trigger the event rather than from the genuinely stochastic nature of the processes involved taking atmospheric pollution level as the state variable it is found that uncertainty implies the existence of an equilibrium interval within which the emission rate of the greenhouse gases should be kept equal to the natural removal rate of these gases processes initiated outside the equilibrium interval must converge monotonically to its nearest endpoint the determination of the interval requires no knowledge of the optimal policy in contrast ignoring event occurrence risk implies a single equilibrium level attracting the optimal process from any initial level

a note on seller s optimal credit period and cycle time in a supply chain for deteriorating items with maximum lifetime in 2014 wang et al 2014 extended the model of lou and wang 2012 to incorporate the credit period dependent demand and default risk for deteriorating items with maximum lifetime however the rates of demand default risk and deterioration in the model of wang et al 2014 are assumed to be specific functions of credit period which limits the contributions in this note we first generalize the theoretical results of wang et al 2014 under some certain conditions furthermore we also present some structural results instead of a numerical analysis on variation of optimal replenishment and trade credit strategies with respect to key parameters

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

on backstops and boomerangs environmental r d under technological uncertainty abstract in areas such as climate change the recent economic literature has been emphasizing and addressing the pervasive presence of uncertainty this paper considers a new and salient form of uncertainty namely uncertainty regarding the environmental characteristics of green innovations here rd ii a decreasing probability of finding a backstop leads to the toleration of higher pollution levels slower rd iii learning about the probability of a backstop is driven by failures only and leads to decreasing research incentives and iv small to moderate delays in the resolution of technological uncertainty do not affect the optimal policy

joint pricing and inventory model for deteriorating items with expiration dates and partial backlogging under two level partial trade credits in supply chain abstract this paper develops an inventory model for deteriorating items under a two level partial trade credit with allowable shortages this paper considers a supplier retailer customer supply chain in which a for settling the cost of purchasing the retailer receives a partial trade credit from the supplier and at the same time the retailer offers a separate partial trade credit to the customer b the downstream credit period not only increases demand but also opportunity cost c the deterioration rate is non decreasing over time and the product is fully deteriorated close to its expiration date and d shortages are allowed the objective of the problem is to determine the optimal selling price the optimal replenishment cycle time and the time taken for the inventory to reach zero at the same time such that the total profit per unit is maximized theoretical results are established a numerical example is provided to illustrate the theoretical results and yield some managerial insights

interactive innovation in financial and business services the vanguard of the service revolution abstract the concept of the reverse product cycle as a theoretical model of innovation in services is developed further in this paper using the vanguard sector of financial and business services as a case study example of how innovation operates as an interactive process the parallels between the emerging service revolution and the nineteenth century industrial revolution are explored in order to identify the key characteristics of the vanguard sectors in each technological revolution the particular nature of the new techno economic paradigm based on information technology is then identified leading to a discussion of the unique conjunction of factors favouring financial and business services as the vanguard sector of the service revolution the central part of the paper then offers an elaboration of the reverse product cycle model stressing the interactive nature of the innovation process as it reflects the prevailing technological opportunities market conditions and industry structures within the adopting sector the example of retail banking is used to illustrate how the innovation cycle proceeds from increases in efficiency through improvements in service quality to the generation of new network service products there is then a discussion of the question of the optimal industry structure for innovation suggestion that in the reverse product cycle large corporations are likely to dominate the early stage of incremental process innovations whereas later in the cycle there is an important role for small entrepreneurial firms to advance more radical process and product innovations the concluding section summarises six major characteristics of the service revolution and suggests how it may proceed from its first to its second phase as the focus of innovation shifts from the vanguard sector of financial and business services to a much broader range of higher level knowledge based services many of which are currently delivered by the public sector

economic order quantity under conditionally permissible delay in payments abstract within the economic order quantity eoq framework the main purpose of this paper is to investigate the retailer s optimal replenishment policy under permissible delay in payments all previously published articles dealing with optimal order quantity with permissible delay in payments assumed that the supplier only offers the retailer fully permissible delay in payments if the retailer ordered a sufficient quantity otherwise permissible delay in payments would not be permitted however in this paper we want to extend this extreme case by assuming that the supplier would offer the retailer partially permissible delay in payments when the order quantity is smaller than a predetermined quantity under this condition we model the retailer s inventory system as a cost minimization problem to determine the retailer s optimal inventory cycle time and optimal order quantity three theorems are established to describe the optimal replenishment policy for the retailer some previously published results of other researchers can be deduced as special cases finally numerical examples are given to illustrate all these theorems and to draw managerial insights

an optimal production inventory model for deteriorating items with multiple market demand the global markets of today offer more selling opportunities to the deteriorating items manufacturers but also pose new challenges in production and inventory planning from a production management standpoint opportunities to exploit the difference in the timing of the selling season between geographically dispersed markets for deteriorating items are important to improving a firm s profitability in this paper we examined the above issue with an insightful production inventory model of a deteriorating items manufacturer selling goods to multiple markets with different selling seasons we also provided a solution procedure to find the optimal replenishment schedule for raw materials and the optimal production plan for finished products a numerical example was then used to illustrate the model and the solution procedure finally sensitivity analysis of the optimal solution with respect to major parameters was carried out

learning by doing and the costs of a backstop for energy transition and sustainability we assess the impact of being able to substitute an unlimited but costly energy substitute like wind solar for a non renewable resource like oil coal in a model of sustainable growth the prospects for sustainability on the optimal path depend crucially on the costs of this substitute furthermore the poorer a country measured in terms of capital stock at a given point in time the later it should switch to the renewable substitute and the more likely it will be unsustainable taking learning by doing in account we find that this leads to an earlier switching time but does not guarantee sustainability

optimal pricing and ordering policy under permissible delay in payments abstract many researchers have assumed that the selling price is the same as the purchase cost and developed various eoq models for a retailer when the supplier offers a permissible delay in payments in this paper we complement the shortcoming of their models by considering the difference between the selling price and the purchase cost we then develop an algorithm for a retailer to determine its optimal price and lot size simultaneously when the supplier offers a permissible delay in payments our theoretical result contradicts to their conclusion that the economic replenishment interval and order quantity generally increases marginally under the permissible delay in payments

optimal abatement of carbon emission flows we study optimal carbon capture and storage ccs from point sources taking into account damages incurred from the accumulation of carbon in the atmosphere and exhaustibility of fossil fuel reserves high carbon concentrations call for full ccs meaning zero net emissions we identify conditions under which partial or no ccs is optimal in the absence of ccs the co2 stock might be inverted u shaped with ccs more complicated behavior may arise it can be optimal to have full capture initially yielding a decreasing stock then partial capture while keeping the co2 stock constant and a final phase without capture but with an inverted u shaped co2 stock we also introduce the option of adaptation and provide a unified theory regarding the optimal use of ccs and adaptation

optimal replenishment policies for non instantaneous deteriorating items with price and stock sensitive demand under permissible delay in payment abstract this study is motivated by the paper of chang et al international journal of production economics 123 2010 62 68 we extend their inventory model from two aspects 1 the demand rate as multivariate function of price and level of inventory 2 delay in payment is permissible under these assumptions we first formulated a mathematical model and then some useful theoretical results have been derived to characterize the optimal solutions for non zero and zero ending inventory system numerical examples are presented to illustrate the theoretical results the sensitivity analysis of a suitable example is performed and some managerial insights are proposed our analysis revels that it is more beneficial to keep higher inventory level hoping to stimulate more demand even if it results in non zero ending inventory

innovation and productivity in developing countries a study of argentine manufacturing firms behavior 1992 2001 abstract following the methodology employed in studies for industrialized countries and using panel data from innovation surveys in argentina with information for 1992 2001 this paper contributes to the nascent literature that analyzes the determinants of innovative inputs and outputs and their impacts on manufacturing firms productivity in developing countries the econometric results show that in house r d and technology acquisition expenditures have positive payoffs in terms of enhanced probability of introducing new products and or processes to the market in turn innovators attain higher productivity levels than non innovators the results also show that large firms have a higher probability of engaging in innovation activities and of becoming innovators

stackelberg solution in a vendor buyer supply chain model with permissible delay in payments abstract in practice vendors or sellers often offer their buyers a fixed credit period to settle the account the benefits of trade credit are not only to attract new buyers but also to avoid lasting price competition on the other hand the policy of granting a permissible delay adds not only an additional cost but also an additional dimension of default risk to vendors in this paper we will incorporate the fact that granting a permissible delay has a positive impact on demand but negative impacts on both costs and default risks to establish vendor buyer supply chain models then we will derive the necessary and sufficient conditions to obtain the optimal solution for both the vendor and the buyer under non cooperative stackelberg equilibrium finally we will use two numerical examples to show that 1 granting a permissible delay may significantly improve profits for both the vendor and the buyer 2 the sensitivity analysis on the optimal solution with respect to each parameter and 3 the comparisons between nash and stackelberg solutions

an integrated vendor buyer inventory model with order processing cost reduction and permissible delay in payments trade credit plays an important role in financing for many businesses and industries for the buyers purchased inventory can be considered to be financed in whole or in part with permissible delay in payments during the purchasing process on the other hand both the vendor and buyer take part in order processing cost reduction by applying information technologies such as edi electronic data interchange the order processing cost can also be reduced by adding certain capital investments and this will affect the lot size decisions this article develops an integrated inventory model to determine the optimal inventory policy under conditions of order processing cost reduction and permissible delay in payments and shows that the total annual variable cost function possesses some kinds of convexities a solution procedure is provided to determine the optimal order policy finally a numerical example is presented to illustrate the solution procedure

energy transition under irreversibility a two sector approach in this paper we analyze the optimal energy transition of a two sector economy energy and final goods with exhaustible oil reserves a renewable source of energy and a pollution threat the latter corresponds to a pollution threshold above which a part of the capital is lost following flooding for instance we show that the optimal energy transition path may correspond to a corner regime in which the economy starts using both resources then crosses the pollution threshold and therefore loses a part of its capital at the end the sole adoption of the renewable energy is optimal only in the long run this result is in line with the asymptotic energy transition arguments stating that the transition to clean energy may happen only in the long run we also show that economy reduces the use of energy resource as long as the productivity of capital and energy services is high therefore public policies should promote investments in energy innovation that targets productive sector home appliances and buildings and helps to save both money and energy we extend the present model to allow for additional investment in energy saving technologies our main results show that this additional investment favours the energy transition in the sense that it increases the time within which the economy may experience the catastrophe and the welfare of the society for policy implications economic instruments such as taxes on dirty energy subsidies on clean energy or incentives for energy saving technologies need to be implemented in order to promote the energy transition this is particularly important for developing countries that mostly rely on polluting energy resources and are the most vulnerable to climate change but those economic instruments should be carefully designed in line with the asymptotic energy transition result

innovation without magic bullets stock pollution and r d sequences abstract we study the optimal r d trajectory in a setting where new technologies are never perfect backstops in the sense that there is no perfectly clean technology that eventually solves the pollution problem once and for all new technologies have strings attached i e each emits a specific stock pollutant damages are convex in individual pollution stocks but additive across stocks creating gains from diversification the research and pollution policies are tightly linked in such a setting we derive the optimal pollution path and r d program pollution stocks overshoot and in the long run all available technologies produce research is sequential and the optimal portfolio of technologies is finite

a comprehensive extension of optimal ordering policy for stock dependent demand under progressive payment scheme in a recent paper soni and shah 2008 presented an inventory model with a stock dependent demand under progressive payment scheme assuming zero ending inventory and adopting a cost minimization objective however with a stock dependent demand a non zero ending stock may increase profits resulting from the increased demand this work is motivated by soni and shah s 2008 paper extending their model to allow for 1 a non zero ending inventory 2 a profit maximization objective 3 a limited inventory capacity and 4 deteriorating items with a constant deterioration rate for the resulted model sufficient conditions for the existence and uniqueness of the optimal solution are provided finally several economic interpretations of the theoretical results are also given

lot sizing policies for deteriorating items with expiration dates and partial trade credit to credit risk customers abstract in practice a credit worthy retailer frequently receives a permissible delay on the entire purchase amount without collateral deposits from his her supplier i e an up stream full trade credit by contrast a retailer usually requests his her credit risk customers to pay a fraction of the purchase amount at the time of placing an order and then grants a permissible delay on the remaining balance i e a down stream partial trade credit in addition many products such as blood banks pharmaceuticals fruits vegetables volatile liquids and others deteriorate constantly and have their expiration dates however not many researchers have taken the expiration date of a deteriorating item into consideration the purpose of this paper is to establish optimal lot sizing policies for a retailer who sells a deteriorating item to credit risk customers by offering partial trade credit to reduce his her risk the proposed model is a generalized case of many previous models by applying theorems in pseudo convex fractional functions we can easily prove that the optimal solution not only exists but is also unique moreover we propose three discrimination terms which can easily identify the optimal solution among all possible alternatives finally some numerical examples are presented to highlight the theoretical results and managerial insights

regulating environmental threats environmental consequences of natural resource exploitation often entail threats of future occurrences of detrimental abrupt events rather than or in addition to inflicting a damage gradually the possibility of abrupt occurrence of climate change related calamities is a case in mind the uncertainty associated with the realization of these threats and their public bad nature complicate the design of optimal economic response we derive a pigouvian hazard tax schedule that implements the socially optimal outcome the tax is based on the expected cost of the hazard generating activities and serves to reduce hazardous emissions well in advance of the catastrophic occurrence a numerical example illustrates possible effects of the proposed regulation scheme implications for climate policy are discussed

inspection policy for inventory system with deteriorating products abstract typical inventory models usually focus on screening out the deteriorating items not much attention is paid to the situation that a proportion of deteriorated items are sold to consumers together with serviceable items during a replenishment cycle this paper first presents a model to formulate the process of such kind of mixed sales a simple closed form solution is obtained for maximizing the net profit per unit time under the assumption of small deterioration rate the effect of shortage back ordering is then considered and closed form solutions of optimal ordering quantity and replenishment time are obtained under similar assumption we further study the effect of inspection policies on optimal decisions for a deteriorating inventory system a dynamic programming approach is proposed for solving the optimal policy numerical examples are then provided to demonstrate our conclusions and results

growth renewables and the optimal carbon tax optimal climate policy is investigated in a ramsey growth model of the global economy with exhaustible oil reserves an infinitely elastic supply of renewables stock dependent oil extraction costs and convex climate damages four regimes can occur depending on the initial social cost of oil being larger or smaller than that of renewables and depending on the initial oil stock being large or small we also offer some policy simulations for the first and second regime which illustrate that with a lower discount rate more oil is left in situ and renewables are phased in more quickly we identify the conditions under which the optimal carbon tax rises or decreases subsidizing renewables without a carbon tax induces more oil to be left in situ and a quicker phasing in of renewables but oil is depleted more rapidly initially the net effect on global warming is ambiguous abstract from author

carbon taxes a drop in the ocean or a drop that erodes the stone the effect of carbon taxes on technological change abstract we develop an economic partial equilibrium model for energy supply and demand with capital and labor as production factors and endogenous technological change through learning by research and learning by doing our model can reproduce the learning curve typical for bottom up energy system models the model also produces an endogenous s curved transition from fossil fuel energy sources to carbon free energy sources over the coming two centuries we use the model to study carbon taxes effects on fossil fuel and carbon free energy use and carbon dioxide emissions it is shown that without induced technological change carbon taxes have a modest effect on emissions while with induced technological change they accelerate the substitution of carbon free energy for fossil fuels substantially

an economic order quantity model for deteriorating items with partially permissible delay in payments linked to order quantity abstract to attract more sales suppliers frequently offer a permissible delay in payments if the retailer orders more than or equal to a predetermined quantity w in this paper we generalize goyal s k 1985 eoq under conditions of permissible delay in payments journal of the operational research society 36 335 338 economic order quantity eoq model with permissible delay in payment to reflect the following real world situations 1 the retailer s selling price per unit is significantly higher than unit purchase price 2 the interest rate charged by a bank is not necessarily higher than the retailer s investment return rate 3 many items such as fruits and vegetables deteriorate continuously and 4 the supplier may offer a partial permissible delay in payments even if the order quantity is less than w we then establish the proper mathematical model and derive several theoretical results to determine the optimal solution under various situations and use two approaches to solve this complex inventory problem finally a numerical example is given to illustrate the theoretical results

innovation in services the purpose of this article is to lay the foundations of a theory that can be used to interpret innovation processes in the service sector the hypothesis underpinning this article is based on lancaster s definition of the product in both manufacturing and services as a set of service characteristics the article follows the example of those who have sought to apply lancaster s work to technological phenomena various modes of innovation in the service sectors are highlighted and illustrated