a dynamic approach to the environmental kuznets curve hypothesis abstract the environmental kuznets curve ekc hypothesis states that pollution levels increase as a country develops but begin to decrease as rising incomes pass beyond a turning point in ekc analyses the relationship between environmental degradation and income is usually expressed as a quadratic function with the turning point occurring at a maximum pollution level other explanatory variables have been included in these models but income regularly has had the most significant effect on indicators of environmental quality one variable consistently omitted in these relationships is the price of energy this paper analyzes previous models to illustrate the importance of prices in these models and then includes prices in an econometric ekc framework testing energy income and co2 income relationships these long run price income models find that income is no longer the most relevant indicator of environmental quality or energy demand indeed we find no significant evidence for the existence of an ekc within the range of current incomes for energy in the presence of price and trade variables

questioning the empirical basis of the environmental kuznets curve for co2 new evidence from a panel stationarity test robust to multiple breaks and cross dependence abstract this paper investigates the time series properties of per capita co2 emissions and per capita gdp levels for a sample of 86 countries over the period 1960 2000 for that purpose we employ a state of the art panel stationarity test which incorporates multiple shifts in level and slope thereby controlling for cross sectional dependence through bootstrap methods our analysis renders clear cut evidence that per capita gdp levels are nonstationary for the world as a whole while per capita co2 is found to be regime wise trend stationary the analysis of country groups shows that for africa and asia per capita co2 is best described as nonstationary while per capita gdp appears stationary around a broken trend in addition we find evidence of regime wise trend stationarity in both variables for the country groups consisting of america europe and oceania the results of our analysis carry important implications for the statistical modelling of the environmental kuznets curve for co2 since the differing order of integration in both variables for the world as a whole and for africa and asia calls into question the validity of panel cointegration techniques which assume that both variables are nonstationary and cointegrated with one another cointegration techniques would not be appropriate either for the case of america europe and oceania which are characterised by per capita gdp and co2 emissions being stationary around a broken trend similar conclusions are reached when we analyse country groups based on levels of development failure to properly characterise the time series properties of the data by not controlling for an unknown number of structural breaks and for cross sectional dependence could be responsible for the fragility and lack of robustness surrounding the estimation of environmental kuznets curves

computing the non stationary replenishment cycle inventory policy under stochastic supplier lead times in this paper we address the general multi period production inventory problem with non stationary stochastic demand and supplier lead time under service level constraints a replenishment cycle policy r n s n is modeled where r n is the n th replenishment cycle length and s n is the respective order up to level we propose a stochastic constraint programming approach for computing the optimal policy parameters in order to do so a dedicated global chance constraint and the respective filtering algorithm that enforce the required service level are presented our numerical examples show that a stochastic supplier lead time significantly affects the structure of the optimal policy with respect to the case in which the lead time is assumed to be deterministic or absent

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

is there a turning point in the relationship between income and energy use and or carbon emissions abstract we analyze the effect of fuel mix model specification and the level of development on the presence and size of a turning point in the relationship between income and energy use and or carbon emissions the results indicate that fuel mix the specification for income and the level of economic development affect conclusions about whether there is a turning point in the relationship between economic activity and energy use and carbon emissions including fuel shares generally reduces the size of a turning point that is estimated from a panel that includes observations from both oecd and non oecd nations but this result varies according to the level of development for oecd nations there is limited support for a turning point in the relationship between income and per capita energy use and or carbon emissions for non oecd nations there is no turning point in the relationship between income and either energy use or carbon emissions instead the relationship is positive together the results indicate that forecasters and policy makers should not depend on a turning point in the relationship between income and energy use or carbon emissions to reduce either

a simple approach for assessing the cost of system nervousness abstract a well known problem in coordinating supply chain inventories is that replenishment decisions are revised due to stochastic demands this issue is often referred to as system nervousness the literature distinguishes between two types of nervousness setup oriented and quantity oriented it is widely accepted that cost of nervousness is difficult to measure we argue that this cost can be evaluated by means of three well established inventory control strategies static uncertainty dynamic uncertainty and static dynamic uncertainty these strategies reflect extreme cases with regard to the setup and the quantity oriented nervousness and provide a simple yet an objective measure to assess the cost of system nervousness our results are of practical importance we highlight that the setup oriented nervousness which is considered to be the most critical in practice can be eliminated with a minor cost penalty this is however not the case for the quantity oriented nervousness

co2 emissions energy consumption and economic growth in bric countries abstract this paper examines dynamic causal relationships between pollutant emissions energy consumption and output for a panel of bric countries over the period 1971 2005 except for russia 1990 2005 in long run equilibrium energy consumption has a positive and statistically significant impact on emissions while real output exhibits the inverted u shape pattern associated with the environmental kuznets curve ekc hypothesis with the threshold income of 5 393 in logarithms in the short term changes in emissions are driven mostly by the error correction term and short term energy consumption shocks as opposed to short term output shocks for each country short term deviations from the long term equilibrium take from 0 770 years russia to 5 848 years brazil to correct the panel causality results indicate there are energy consumption emissions bidirectional strong causality and energy consumption output bidirectional long run causality along with unidirectional both strong and short run causalities from emissions and energy consumption respectively to output overall in order to reduce emissions and not to adversely affect economic growth increasing both energy supply investment and energy efficiency and stepping up energy conservation policies to reduce unnecessary wastage of energy can be initiated for energy dependent bric countries

dynamic uncapacitated lot sizing with random demand under a fillrate constraint abstract this paper deals with the single item dynamic uncapacitated lot sizing problem with random demand we propose a model based on the static uncertainty strategy of bookbinder and tan 1988 in contrast to these authors we use exact expressions for the inventory costs and we apply a fillrate constraint we present an exact solution method and modify several well known dynamic lot sizing heuristics such that they can be applied for the case of dynamic stochastic demands a numerical experiment shows that there are significant differences in the performance of the heuristics whereat the ranking of the heuristics is different from that reported for the case of deterministic demand

augmenting the lot sizing order quantity when demand is probabilistic abstract in this paper we consider a single item discrete time lot sizing situation where demand is random and its parameters e g mean and standard deviation can change with time for the appealing criterion of minimizing expected total relevant costs per unit time until the moment of the next replenishment we develop two heuristic ways of selecting an appropriate augmentation quantity beyond the expected total demand through to the planned deterministic time of the next replenishment the results of a set of numerical experiments show that augmentation is important particularly when orders occur frequently i e the fixed cost of a replenishment is low relative to the costs of carrying one period of demand in stock and the coefficient of variability of demand is relatively low but also under other specified circumstances the heuristic procedures are also shown to perform very favourably against a hindsight baseline s s policy especially for larger levels of non stationarity

carbon dioxide emissions and economic growth panel data evidence from developing countries in this paper we test the environment kuznet s curve ekc hypothesis for 43 developing countries we suggest examining the ekc hypothesis based on the short and long run income elasticities that is if the long run income elasticity is smaller than the short run income elasticity then it is evident that a country has reduced carbon dioxide emissions as its income has increased our empirical analysis based on individual countries suggests that jordan iraq kuwait yemen qatar the uae argentina mexico venezuela algeria kenya nigeria congo ghana and south africa approximately 35 per cent of the sample carbon dioxide emissions have fallen over the long run that is as these economies have grown emissions have fallen since the long run income elasticity is smaller than the short run elasticity we also examine the ekc hypothesis for panels of countries constructed on the basis of regional location using the panel cointegration and the panel long run estimation techniques we find that only for the middle eastern and south asian panels the income elasticity in the long run is smaller than the short run implying that carbon dioxide emission has fallen with a rise in income

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

between estimates of the emissions income elasticity abstract recent papers by wagner and vollebergh et al point out some fundamental econometric problems with traditional methods of estimating the environmental kuznets curve ekc and propose alternative approaches that avoid these issues wagner notes that traditional methods do not take into account the presence of powers of unit root variables and cross sectional dependence in the data while vollebergh et al point out that the time effects are not uniquely identified in the ekc model the between estimator is a simple estimator that also addresses the concerns of these authors it makes no a priori assumption about the nature of the time effects and is likely to provide consistent estimates of long run relationships in real world data situations i apply several common panel data estimators including the between estimator to oecd and global carbon and sulfur emissions datasets the between estimates of the sulfur income elasticity are 0 732 in the oecd and 1 067 in the global data set and the estimated carbon income elasticity is 1 612 in the oecd and 1 509 globally

the effects of environmental regulation and technical progress on co2 kuznets curve an evidence from china based on environmental kuznets curve theory a panel data model which takes environmental regulation and technical progress as its moderating factors was developed to analyse the institutional and technical factors that affect the path of low carbon economic development the results indicated that there was a co2 emission kuznets curve seen in china environmental regulation had a significant moderating effect on the curve and the inflection of co2 emissions could come substantially earlier under stricter environmental regulation meanwhile the impact of technical progress on the low carbon economic development path had a longer hysteresis effect but restrained co2 emission during its increasing stage and accelerated its downward trend during the decreasing stage which was conducive to emission reduction strict environmental regulation could force the high carbon emitting industries to transfer from the eastern regions to the central or the western regions of china which would make the co2 kuznets curve higher in its increasing stage and lower in its decreasing stage than that under looser regulation furthermore energy efficiency energy structure and industrial structure exerted a significant direct impact on co2 emissions we should consider the above factors as essential in the quest for low carbon economic development

environmental degradation economic growth and energy consumption evidence of the environmental kuznets curve in malaysia this paper tests for the short and long run relationship between economic growth carbon dioxide co2 emissions and energy consumption using the environmental kuznets curve ekc by employing both the aggregated and disaggregated energy consumption data in malaysia for the period 1980 2009 the autoregressive distributed lag ardl methodology and johansen juselius maximum likelihood approach were used to test the cointegration relationship and the granger causality test based on the vector error correction model vecm to test for causality the study does not support an inverted u shaped relationship ekc when aggregated energy consumption data was used when data was disaggregated based on different energy sources such as oil coal gas and electricity the study does show evidences of the ekc hypothesis the long run granger causality test shows that there is bi directional causality between economic growth and co2 emissions with coal gas electricity and oil consumption this suggests that decreasing energy consumption such as coal gas electricity and oil appears to be an effective way to control co2 emissions but simultaneously will hinder economic growth thus suitable policies related to the efficient consumption of energy resources and consumption of renewable sources are required

identifying reduced form relations with panel data the case of pollution and income abstract in this paper we propose a solution to the non robustness that plagues the estimation of inverted u shaped relationships using panel data such as the relation between pollution and income when dependent and independent variable like pollution and income are both time related separating the effect of the independent variable from time effects brings about a fundamental identification dilemma the imposition of restrictions on the controls might drive the shape of the relationship between the dependent pollution and independent income variables our solution consists of imposing the very weak constraint that arbitrary cross sectional units have the same relationship we apply our methodology to two widely studied cases namely so 2 and co 2 emissions interestingly our estimates are insensitive to the required subjective choices but also strongly differ from the literature so far we find consistent positive income effects for both cases and time effect estimates with a clear u shaped trend for so 2 emissions but only slightly so for co 2 emissions

investigating the environmental kuznets curve hypothesis in vietnam this study investigates the existence of the environmental kuznets curve ekc hypothesis in vietnam during the period 1981 2011 to realize the goals of this study a pollution model was established applying the autoregressive distributed lag ardl methodology the results revealed that the pollution haven hypothesis does exist in vietnam because capital increases pollution in addition imports also increase pollution which indicates that most of vietnam s imported products are energy intensive and highly polluted however exports have no effect on pollution which indicates that the level of exports is not significant enough to affect pollution moreover fossil fuel energy consumption increases pollution while renewable energy consumption has no significant effect in reducing pollution furthermore labor force reduces pollution since most of vietnam s labor force is in the agricultural and services sectors which are less energy intensive than the industrial sector based on the obtained results the ekc hypothesis does not exist because the relationship between gdp and pollution is positive in both the short and long run

economic growth energy conservation and emissions reduction a comparative analysis based on panel data for 8 asian pacific countries this study was conducted to evaluate the causality between energy consumption gdp growth and carbon emissions for eight asia pacific countries from 1971 to 2005 using the panel data the results indicate that there are long run equilibrium relationships between these variables additionally causality from energy consumption to co2 emissions was observed generally but there were some opposite relationships also parameter estimations of the panel data model indicate that there are great differences in the carbon emissions the efficiencies of energy use carbon emissions of unit gdp and unit energy consumption between developed and developing countries the base carbon emissions per capita energy consumption and efficiency of energy use in developing countries are far lower than in developed countries however the co2 emissions per unit of energy use is higher although developing countries may reduce their co2 emission per unit energy use total energy consumption will rise rapidly with economic development thus developing countries must determine how to undergo economic growth while conserving energy and reducing emissions to respond to global climate change it is necessary to develop innovative technology for energy use transform the energy structure and conduct the clean development mechanism

multiple items procurement under stochastic nonstationary demands abstract in the consumer goods wholesaling and retailing industry a large number of stock keeping units must be managed on a regular basis the items are typically purchased in families each family being associated with a specific external vendor and usually there are some constraints on family order quantities and there are frequent opportunities to buy at a temporary low price the demand for an item is often stochastic and not stationary in this paper by computing procurement plans over rolling planning horizons we transform this difficult sequential decision problem into a multi period static decision problem under risk the problem is initially formulated as a stochastic program with simple recourse and a branch and bound algorithm is designed to solve an equivalent deterministic program a piecewise concave approximation is proposed to reduce this program to a linear program with one 0 1 variable per planning period the performances of the algorithms are studied in two simulation experiments the simulations show that when planning over a rolling horizon the approach proposed yields excellent results

the environmental kuznets curve ekc theory part a concept causes and the co2 emissions case abstract the main purpose of this study is to capture the main features of the environmental kuznets curve ekc concept according to the ekc theory the process of economic growth is expected eventually to limit the environmental degradation created in the early stages of development the ekc concept leads many researchers from the early 1990s to assume that each economy should focus on its growth and any environmental problems will be eventually eliminated by the process of economic growth several studies attempt to test empirically the ekc hypothesis using data on many countries and examining various types of environmental degradation while other studies examine the underlying factors that may drive such a relationship this article reviews the evolution of the ekc concept and the possible causes of an ekc pattern like the distribution of income the international trade pollution haven hypothesis structural changes technical progress and improvements in energy efficiency institutions and governance and consumer preferences as co2 emissions are a pollutant with global effects several studies deal with the possible ekc pattern for co2 emissions and these studies are discussed separately the various critiques on the ekc concept are reviewed in the second article of this work

global observation of ekc hypothesis for co2 sox and nox emission a policy understanding for climate change mitigation in bangladesh abstract environmental kuznets curve ekc hypothesis is critical to understanding the developmental path of a nation in relation to its environment how the effects of economic development processes dictate environmental changes can be found through the study of ekc to understand the ekc phenomena for climate change this study was undertaken by reviewing the available literature as co2 sox and nox are the significant greenhouse gases ghg responsible for global warming thus leading to climate change the study focused on those ghgs for ekc consideration with an understanding of the different ekc trajectories an attempt was made to determine the implications for the economic development of bangladesh in regards to the ekc it was shown that ekc for co2 was following a monotonous straight line in most cases sox were shown to follow the full trajectory of the ekc in most situations and nox was shown the hope only for the developed countries getting the low income turning point the type of economic policy that bangladesh should follow in regards to the discussed pollutants and sources is also revealed from these discussions contributions to policy stimulation in bangladesh are likely to be made

environmental kuznet s curve for india evidence from tests for cointegration with unknown structuralbreaks this study revisits the cointegrating relationship between carbon emission energy use economic activity and trade openness for india using threshold cointegration tests with a view to testing the environmental kuznet s curve hypothesis in the presence of possible regime shift in long run relationship of the variables for the period 1971 to 2008 the article confirms the existence of regime shift or threshold cointegration among the variables and environmental kuznet s curve for india it challenges previous empirical works for india which fail to establish cointegrating relationship among these variables and explains its logical and econometric reasons the study finds that the carbon emission is highly elastic with respect to real per capita income and energy use in india this finding is critical and warns successful design and execution of energy and environmental policy framework which would pave the low carbon sustainable growth path inindia

investigation of the environmental kuznets curve for carbon emissions in malaysia do foreign direct investment and trade matter abstract environmental degradation has become a central issue of discussion among the economists and environmentalists in view of malaysia s position as one of the main contributors to co2 emissions in asia and its status as a fast growing economy it is vital therefore to conduct a study to identify the relationship between economic growth and co2 emissions for malaysia this study attempts to examine empirically the environmental kuznets curve hypothesis for malaysia in the presence of foreign direct investment and trade openness both in the short and long run for the period 1970 to 2008 the bounds testing approach and granger causality methodology are applied to test the interrelationships of the variables the results of our study indicate that the inverted u shaped relationship does exist between economic growth and co2 emission in both the short and long run for malaysia after controlling for two additional explanatory variables namely fdi and trade importantly the results of the study also provide some crucial policy recommendations to the policy makers

accounting for race and gender differences in college wage premium changes much recent research has been devoted to the rapid rise in the college wage premium during the 1980s 3 5 10 13 14 murphy and welch 13 estimated that between 1979 and 1986 the college wage premium for all age groups increased almost 20 percentage points while the college wage premium for workers with one to five years of experience grew by 38 percentage points while the size of the college wage premium increase is impressive especially among recent graduates there is substantial disparity in this change among individual race gender groups 2 4 coleman 4 found that the wage premium increase for graduates with one to five years of experience was 45 percentage points for white men 30 percentage points for white women and 27 percentage points for black men while the wage premium decreased by 3 percentage points for black women

the nexus between carbon emissions energy consumption and economic growth in middle east countries a panel data analysis abstract the environmental kuznets curve ekc hypothesis assumes that there is an inverted u shaped relationship between environmental degradation and income per capita in other words as a country grows it is assumed that its environmental quality improves in this study we aim to test the ekc hypothesis for 12 middle east countries during the period 1990 2008 by employing recently developed panel data methods our results provide evidence contrary to the ekc hypothesis we found evidence favorable to the u shaped ekc for 5 middle east countries whereas an inverted u shaped curve was identified for only 3 middle east countries furthermore there appear to be no causal links between income and co 2 emissions for the other 4 countries regarding the direction of causality there appears to be a unidirectional causality from economic growth to energy consumption in the short run in the long run however the unidirectional causality chain runs from energy consumption and economic growth to co 2 emissions we also suggest some crucial policy implications depending on these results

carbon dioxide emission and income a temporal analysis of cross country distributional patterns the existence of a cointegrating relationship between income and co2 emission for individual country groups suggests existence of a corresponding relationship between the inter country disparities in the levels of income and co2 emission this paper explores the relationship between the patterns of cross country distribution of income and co2 emission and temporal shifts in such a relationship this paper also examines how the mean level of per capita co2 emission and its distributional inequality are related to the corresponding mean income level and the distributional inequality of income the analysis is based on a cross country panel data set at the level of country group environmental quality demanded is treated as a private good and not as a public good as done in most other studies the technique of lorenz and specific concentration curve analysis are used as the basic analytical framework to argue that a measure of relative distributional inequality of income should be used as an explanatory variable in the environmental kuznets curve ekc relationship along with the mean income level in the empirical exercise johansen s cointegration analysis technique is used to explore existence of statistically significant cointegrating vector s relating mean level of emission and specific concentration ratio scr of emission to mean income level and lorenz ratio lr of income the empirical results confirm that the pattern of cross country income distribution has significant effect on the mean level of emission for all the country groups considered

order quantities for perishable inventory control with non stationary demand and a fill rate constraint abstract we study the practical decision problem of fresh food production with a long production lead time to decide every period e g week how many items to produce when a batch is ready for use its items have a fixed shelf life after which the items become waste in the sense that they cannot be sold anymore the demand for fresh food products is uncertain and highly fluctuating mainly caused by price promotions of retail organisations we focus on cases where a so called cycle fill rate service level requirement applies we investigate the generation of a production plan that fixes the timing and quantity of the production for a finite time horizon to minimise waste one issues the oldest items first i e a fifo issuing policy in case of out of stock sales are lost we model this decision problem as a stochastic programming sp model the objective of our study is to find order quantities for the sp model that approximately meet cycle fill rate service level requirements while keeping outdating low to find approximate solutions for the sp model an milp model is developed the milp model is a deterministic approximation that generates feasible replenishment quantities in less than a second with a scenario based minlp approach optimal solutions are generated for a large sample of demand paths as a benchmark for the milp solutions we show that the milp model is suitable for practical use if the setup cost is such that the replenishment cycles in the production plan are close to or of the same length as the maximum shelf life in those cases the expected total costs are close to the costs of the optimal solution and the average fill rate is close to the required one

economic models for the environmental kuznets curve a survey abstract the environmental kuznets curve ekc refers to an inverted u shaped relationship between some pollutant level and per capita income i e the environmental quality deteriorates at early stages of economic growth and subsequently improves at a later stage since the early 1990s a considerable number of empirical studies have been conducted on the ekc and although there is no conclusive proof it has been recognized that the ekc emerges as an empirical regularity however some recent studies cast doubt on the concept and methodology of empirical results and evidence of the existence of the ekc has been questioned in fact how economic growth affects the environmental quality i e the shape of the ekc is still controversial in order to identify the actual relationship between the environmental quality and economic growth it is essential to develop economic models from various points of view this paper overviews the current stage of theoretical models that explain such relationship

income and emission a panel data based cointegration analysis this paper presents the results of an investigation of the causality issue of incomeemission relationship based on time series econometric techniques of unit root test cointegration and related error correction model for a panel data set here the nature of causality between per capita co2 emission pcco2 and per capita gdp pcgdp has been examined using a cross country panel data set covering 88 countries for the period 1960 90 using the panel unit root test procedure of im et al 1997 ips we have found that the hypothesis of unit root i e non stationarity of the time series of pcgdp and pcco2 can not be rejected for individual country groups as both the variables are found to follow i 1 process we next have performed the panel data co integration test and finally we have estimated the ecm for these country groups for which significant income emission cointegration was obtained to explore the nature of dynamics implicit in the given panel data set our findings suggest that there is more or less a bi directional causal relationship between income pcgdp and co2 emission pcco2 for africa central america america as a whole eastern europe western europe europe as a whole and the world as a whole that means the movement of the one variable directly affects the other variable through a feedback system thus the policy makers should be cautious to make proper decision about the control of emission level

the stochastic dynamic production inventory lot sizing problem with service level constraints abstract this paper addresses the multi period single item inventory lot sizing problem with stochastic demands under the static dynamic uncertainty strategy of bookbinder and tan manage sci 34 1988 1096 in the static dynamic uncertainty strategy the replenishment periods are fixed at the beginning of the planning horizon but the actual orders are determined only at those replenishment periods and will depend upon the demand that is realised their solution heuristic was a two stage process of firstly fixing the replenishment periods and then secondly determining what adjustments should be made to the planned orders as demand was realised we present a mixed integer programming formulation that determines both in a single step giving the optimal solution for the static dynamic uncertainty strategy the total expected inventory holding ordering and direct item costs during the planning horizon are minimised under the constraint that the probability that the closing inventory in each time period will not be negative is set to at least a certain value this formulation includes the effect of a unit variable purchase production cost which was excluded by the two stage bookbinder tan heuristic an evaluation of the accuracy of the heuristic against the optimal solution for the case of a zero unit purchase production cost is made for a wide variety of demand patterns coefficients of demand variability and relative holding cost to ordering cost ratios the practical constraint of non negative orders and the existence of the unit variable cost mean that the replenishment cycles cannot be treated independently and so the problem cannot be solved as a stochastic form of the wagner whitin problem applying the shortest route algorithm

the environmental kuznets curve ekc theory part b critical issues according to the environmental kuznets curve ekc theory the process of economic growth is expected to limit the environmental degradation created in the early stages of development the first article of this study reviews the empirical studies examining various factors other than income that may lead to an ekc pattern the current article reviews in the first part the major critiques on the ekc speculation which relate to the following issues the normal distribution of world income the feedback from environmental degradation to economic growth the characteristics of the pollutant in question various econometric issues the evolution of consumption when income rises and the assumption about a common developmental pattern in all countries the second part discusses additional matters reported indirectly in the literature and or must be further examined there are doubts whether the gdp series captures the transition of production to the three productive sectors in empirical estimations and whether services are less polluting compared to industry activities finally the original kuznets theory which laid the groundwork for the ekc concept does not seem to solve income inequality problems

optimal dynamic procurement policies for a storable commodity with levy prices and convex holding costs abstract in this paper we study a continuous time stochastic inventory model for a commodity traded in the spot market and whose supply purchase is affected by price and demand uncertainty a firm aims at meeting a random demand of the commodity at a random time by maximizing total expected profits we model the firm s optimal procurement problem as a singular stochastic control problem in which controls are nondecreasing processes and represent the cumulative investment made by the firm in the spot market a so called stochastic monotone follower problem we assume a general exponential levy process for the commodity s spot price rather than the commonly used geometric brownian motion and general convex holding costs we obtain necessary and sufficient first order conditions for optimality and we provide the optimal procurement policy in terms of a base inventory process that is a minimal time dependent desirable inventory level that the firm s manager must reach at any time in particular in the case of linear holding costs and exponentially distributed demand we are also able to obtain the explicit analytic form of the optimal policy and a probabilistic representation of the optimal revenue the paper is completed by some computer drawings of the optimal inventory when spot prices are given by a geometric brownian motion and by an exponential jump diffusion process in the first case we also make a numerical comparison between the value function and the revenue associated to the classical static newsvendor strategy

the co2 emissions income nexus evidence from rich countries the paper attempts to test the environment kuznets curve ekc hypothesis for 36 high income countries for the period 1980 2005 the test is based on the suggestion of narayan and narayan 2010 various panel data unit root and co integration tests are applied carbon dioxide co2 emissions and gdp series are integrated of order one and co integrated especially after controlling for cross sectional dependence additionally the blundell bond system generalised methods of moments gmm is employed to conduct a panel causality test in a vector error correction mechanism vecm setting unidirectional causality running from real per capita gdp to per capita co2 emissions is uncovered in both the short run and the long run the empirical analysis based on individual countries provides evidence of an ekc for greece malta oman portugal and the united kingdom however it can be observed that for the whole panel a 1 increase in gdp generates an increase of 0 68 in co2 emissions in the short run and 0 22 in the long run the lower long run income elasticity does not provide evidence of an ekc but does indicate that over time co2 emissions are stabilising in the rich countries

revisiting environmental kuznets curves through the energy price lens abstract the goal of this paper is to provide new insights to elucidate the inconclusive results from the environmental kuznets curve ekc empirical literature for the first time in empirical literature an econometric analysis includes the relative prices for several energy sources the paper provides strong evidence on the relevance of energy prices to co 2 emissions accordingly one reason for the lack of agreement in the ekc literature may be the absence of energy prices in empirical exercises the presence of relative energy price changes in the econometric specification confirms a monotonic and positive relationship between co 2 and gross domestic product gdp therefore we may conclude that there is a decoupling process but without reaching any turning point on that relationship the policy implications are straightforward direct climate action by policy makers is required to break the positive relationship between co 2 and gdp that conclusion has been reinforced by the reduction of energy prices since the middle of 2014 otherwise the trend in energy prices may reverse the relative decarbonisation processes accounted for in recent years in major developed countries

inventory models with minimal service level constraints abstract this paper investigates inventory models in which the stockout cost is replaced by a minimal service level constraint slc that requires a certain level of service to be met in every period the minimal service level approach has the virtue of simplifying the computation of an optimal ordering policy because the optimal reorder level is solely determined by the minimal slc and demand distributions it is found that above a certain critical service level the optimal s s policy collapses to a simple base stock or order up to level policy which is independent on the cost parameters this shows the minimal slc models to be qualitatively different from their shortage cost counterparts we also demonstrate that the imputed shortage cost transforming a minimal slc model to a shortage cost model does not generally exist the minimal slc approach is extended to models with negligible set up costs the optimality of myopic base stock policies is established under mild conditions

system dynamics modelling and the environmental kuznets curve in ecuador 1980 2025 abstract is it possible for a country in the process of development to comply with the environmental kuznets curve ekc hypothesis in the medium term this is the question that inspired this study this paper is an extension of a previous study focused on economic development and co2 emissions in the coming years in ecuador robalino lopez et al submitted for publication the main goal of this paper is to analyze whether the ekc hypothesis holds within the period 1980 2025 under four different scenarios this paper uses co integration techniques stock and watson 2010 to test the existence of the ekc hypothesis in ecuador in the medium term using jaunky s 2011 specification our proposal goes a step further than previous contributions and intends to see under which conditions a country could approach the fulfilment of this hypothesis in the medium term results do not support the fulfilment of the ekc nevertheless our estimations show that ecuador could be on the way to achieving environmental stabilization in the near future if economic growth is combined with an increase in the use of renewable energies an improvement of the productive sectoral structure and the use of a more efficient fossil fuel technology

threshold cointegration and nonlinear adjustment between co2 and income the environmental kuznets curve in spain 1857 2007 abstract article history received 9 march 2011received in revised form 24 february 2012accepted 2 march 2012available online 14 march 2012jel classi cation c2q4keywords environmental kuznets curveco 2 emissionsnonlinear relationshipthreshold cointegration inthispaper wemodelthe long run relationship between per capita co 2 and per capita income for the spanisheconomy over the period 1857 2007 according to the environmental kuznets curve eck the relationshipbetween the two variables has an inverted u shape however previous studies for the spanish economy onlyconsidered the existence of linear relationships such an approach may lack exibility to detect the trueshape of the relationship our empirical methodology accounts for a possible non linear relationship throughthe use of threshold cointegration techniques our results con rm the non linearity of the link between thetwo above mentioned variables pointing to the existence of an environmental kuznets curve for the spanishcase 2012 elsevier b v all rights reserved

inventory policies for systems with stochastic and deterministic demand we consider a periodic review inventory system with demand arriving simultaneously from a deterministic source and a random source the deterministic demand has to be satisfied immediately and the stochastic demand can be backordered assuming that the stochastic demand is never backlogged if there is stock in the system we prove that a modified s s policy is optimal under general conditions if there is a setup cost if there is a smoothing cost instead of the setup cost we observe that the problem corresponds to a standard model with one source of demand

an approach to evaluate the impact of interaction between demand forecasting method and stock control policy on the inventory system performances abstract usually in stock control studies demand data are considered as an input to the model without explicitly considering that they are the results of a demand forecasting system stock control system is examined independently of the demand forecasting system and it is assumed that demand data or forecast errors have been properly modelled however the interactions that may exist between demand forecasting methods and stock control systems in terms of their effects on global system performances are not considered in the paper an approach for evaluating these interactions based on a comparative simulation test of global system costs using historical data is presented the approach is explained through a real case the replenishment from different suppliers of a central depot of tinned food which supplies more than 700 items to warehouses at the lower echelon results of the simulation study show that traditional measures of forecast errors cannot be taken as sole indicators for the choice among different demand forecasting methods these methods on the contrary have to be evaluated on the basis of total costs and service level of the global inventory control system

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

a spatial panel data approach to estimating u s state level energy emissions we take advantage of a long panel data set to estimate the relationship between u s state level carbon dioxide co2 emissions economic activity and other factors we specify a reduced form energy demand model to account for energy consumption activities that drive energy related emissions we contribute to the literature by exploring several spatial panel data models to account for spatial dependence between states estimation results and rigorous diagnostic analysis suggest that 1 economic distance plays a role in intra and inter state co2 emissions and 2 there are statistically significant positive economic spillovers and negative price spillovers to state level emissions

co2 emissions energy consumption and output in france abstract this paper examines the dynamic causal relationships between pollutant emissions energy consumption and output for france using cointegration and vector error correction modelling techniques we argue that these variables are strongly inter related and therefore their relationship must be examined using an integrated framework the results provide evidence for the existence of a fairly robust long run relationship between these variables for the period 1960 2000 the causality results support the argument that economic growth exerts a causal influence on growth of energy use and growth of pollution in the long run the results also point to a uni directional causality running from growth of energy use to output growth in the short run

revisiting the environmental kuznets curve in a global economy the present study deals with an empirical investigation between co2 emissions energy intensity economic growth and globalization using annual data over the period of 1970 2010 for turkish economy we applied unit root test and cointegration approach in the presence of structural breaks the direction of causality between the variables is investigated by applying the vecm granger causality approach our results confirmed the existence of cointegration between the series the empirical evidence reported that energy intensity and economic growth globalization increase condense co2 emissions the results also validated the presence of environmental kuznets curve ekc the causality analysis shows bidirectional causality between economic growth and co2 emissions this implies that economic growth can be boosted at the cost of environment