control of accumulating stock pollution by heterogeneous producers abstract this paper presents a framework to determine optimal resource allocation over time for the production of a good by heterogeneous producers who generate a stock externality we analyze the optimal intertemporal and quality specific combination of abatement strategies at the source source abatement given by a change in the intensity intensive margin of production and in the chosen technology extensive margin and or removal of existing pollution stock stock abatement the results show how the specifications of the production and the emission functions affect technology adoption and the design of the optimal intertemporal combination of source and stock abatement strategies moreover the paper shows that regulation at the intensive margin cannot be considered as a substitute for a regulation at the extensive margin the paper employs the so called two stage solution approach for solving the resulting quality distributed intertemporal optimal control problem

optimal lot size model for deteriorating items with demand rate dependent on displayed stock level dsl and partial backordering in this paper we consider the problem of determining the lot size of a single deteriorating item with the demand rate dependent on displayed stock level selling price of an item and frequency of advertisement in the popular electronic and print media also through the sales representatives shortages if any are allowed and partially backlogged with a variable rate which depends on the duration of waiting time upto the arrival of next lot here the transportation cost for replenishing the goods is considered explicitly and the storage capacity of the showroom shop is assumed to be limited finite according to the relative size of the stock level dependency demand parameters and the storage capacity of the showroom shop different scenarios with sub scenarios have been mentioned and solved with the help of grg generalised reduced gradient method and the computational procedure the convexity analysis is done by showing the average profit function in each case as pseudo concave to illustrate the results and its significant features a numerical example is given finally to study the effect of changes of demand parameters deterioration backlogging parameters and mark up rate on the maximum initial stock level shortage level frequency of advertisement per cycle along with the maximum average profit are presented numerically

a deterministic inventory model for deteriorating items with stock dependent demand rate abstract a deterministic inventory model is developed by assuming that the demand rate is stock dependent and the items deteriorate at a constant rate the expression for the average net profit over one production run is derived and its optimization with respect to the decision variables q initial stock and t duration of a production cycle is carried out this leads to two highly nonlinear equations which are solved by using a subroutine neqnf in imsl math library in cyber 180 480a computer system the optimal solution so derived is compared with that for the no deterioration 0 case sensitivity of the optimal solution to changes in parameter values is examined several aspects of the functional form for the demand rate are considered in a separate section finally the salient features of the problem and its solution are discussed in brief

inventory policy with time dependent setup cost abstract assume a time interval t is given moreover assume that the setup cost is not constant but varies with the lapse of time our problem is to determine the inventory policy for the given t how often the order is placed during t and how much is ordered at each ordering time point are our main themes we solve these problems in the following ways if frequency of orders for t is given arbitrarily the ordering policy is to be planned by using the techniques of dp by choosing a proper frequency of orders so that it may minimize the total inventory cost required during t an optimal inventory policy for t is determined moreover by applying dp some mathematical properties of this policy are examined even if exact mathematical expressions for frequency of orders and inventory cost are determined their values are obtained these become the merit of applying dp

optimal production management when demand depends on the business cycle we assume that the cumulative consumer demand for an item follows a brownian motion with both the drift and the variance parameters modulated by a continuous time markov chain that represents the regime of the economy the management of the company would like to maintain the inventory level as close as possible to a target inventory level and would also like to produce at a rate that is as close as possible to a target production rate the company is penalized for deviations from the target levels and the objective is to minimize the total discounted penalty costs we consider two models in the first model the management of the company knows the state of the economy whereas in the second model the management does not know it we solve both problems and obtain the optimal production policy and the minimal total expected discounted cost furthermore we compare the total expected discounted costs of the two models and determine the value of knowing the regime of the economy we also solve the above prob

a note on eoq models for deteriorating items under stock dependent selling rate abstract in 1995 padmanabhan and vrat presented inventory models for deteriorating items with stock dependent selling rate and derived the profit functions without backlogging and with complete backlogging first this paper develops the necessary and sufficient conditions of the existence and uniqueness of the optimal solutions of the profit per unit time functions without backlogging and with complete backlogging second this paper explains that it is appropriate to use the newton raphson method to find the optimal solutions of the profit functions per unit time in both situations modelled

optimal ordering and transfer policy for an inventory with stock dependent demand abstract this paper deals with an ordering transfer inventory model to determine the retailer s optimal order quantity and the number of transfers per order from the warehouse to the display area it is assumed that the amount of display space is limited and the demand rate depends on the display stock level the objective is to maximize the average profit per unit time yielded by the retailer the proposed models and algorithms are developed to find the optimal strategy by retailer numerical examples are presented to illustrate the models developed and the sensitivity analysis is also reported

an eoq model with stock dependent demand shortage inflation and time discounting abstract this paper develops a finite time horizon deterministic economic order quantity eoq inventory model with shortages where the demand rate at any instant depends on the on hand inventory stock level at that instant the effects of inflation and the time value of money are taken into account considering two separate inflation rates namely the internal company inflation rate and the external general economy inflation rate the results are discussed with a numerical example and particular case of the model is discussed in brief a sensitivity analysis of the optimal solution with respect to the parameters of the system is carried out

inventory model with stock level dependent demand rate and variable holding cost inventory models in which the demand rate depends on the inventory level are based on the common real life observation that greater product availability tends to stimulate more sales previous models incorporating inventory level dependent demand rate assume that the holding cost is constant for the entire inventory cycle this paper considers the inventory policy for an item with a stock level dependent demand rate and a storage time dependent holding cost the holding cost per unit of the item per unit time is assumed to be an increasing function of the time spent in storage two time dependent holding cost step functions are considered retroactive holding cost increase and incremental holding cost increase procedures are developed for determining the optimal order quantity and the optimal cycle time for both cost structures

an inventory model for deteriorating items with stock dependent consumption rate and shortages under inflation and time discounting this paper derives an inventory model for deteriorating items with stock dependent consumption rate and shortages under inflation and time discounting over a finite planning horizon we show that the total cost function is convex with the convexity a simple solution algorithm is presented to determine the optimal order quantity and the optimal interval of the total cost function the results are discussed with a numerical example and particular cases of the model are discussed in brief a sensitivity analysis of the optimal solution with respect to the parameters of the system is carried out

estimating the demand for a new technology bt cotton and insecticide policies this article examines the potential demand for bt cotton in the southeast from information gathered in the first year of commercialization we combine revealed preference rp data on adoption of bt cotton varieties with stated preference sp data on willingness to adopt to estimate demand using a double bounded maximum likelihood procedure using estimated demand equations we simulate the costs of reducing conventional insecticide applications through subsidization of bt cotton results indicate that reducing cotton insecticide applications by 40 in the southeast would require a 21 acre subsidy with total annual program costs between 53 million and 60 million

an economic model of soil conservation by introducing soil depth and soil loss into a simple model of agricultural production this paper seeks to determine when the private path of erosion differs from the socially optimal path considering the depletion of soil only and abstracting from the environmental disruption caused by erosion the paper argues that under most institutional arrangements the social and private rates of erosion are the same the paper concludes that public policy should be directed toward reducing erosion only when it leads to significant pollution externalities

the econometrics of damage control why specification matters the contribution of damage control agents to production differs fundamentally from that of standard inputs lands labor capital this paper develops an econometric model based on the key characteristics of damage control agents and examines its properties it demonstrates that standard production function specifications overestimate damage control agent productivity and have erroneous implications for the evolution of damage control agent productivity and use in response to changing environments e g the spread of pest resistance it also proposes several alternative specifications and discusses methods for estimating them

project evaluation with democratic decision making what does cost benefit analysis really measure abstract it is often argued that projects involving public good changes should be chosen on the basis of monetary valuation and cost benefit analysis cba however cba is not value free when used to measure welfare it is based on highly controversial value judgements when used to measure efficiency it is based on assumptions of limited relevance to democratic decision making processes cba measures total net willingness to pay neither more nor less while interesting in its own right the normative significance of this indicator is not obvious

natural resource economics and conservation contributions of agricultural economics and agricultural economists research by agricultural economists on natural resources has been distinguished by an interdisciplinary emphasis and a dynamic perspective it has recognized technological and institutional constraints has been oriented toward solving concrete resource management and policy problems and has emphasized empirical and quantitative analysis agricultural economists have introduced methods for evaluating natural resource conservation efforts for predicting adoption of resource conservation technologies and for designing efficient and sustainable resource management policies they have identified ways of improving land management and preventing land degradation proposed reforms of institutions governing water allocation and water quality and introduced policies for balancing environmental and efficiency considerations in the management of pests biodiversity and livestock diseases their research has had substantial impacts on the formulation of resource conservation policies

inventory models with inventory level dependent demand a comprehensive review and unifying theory marketing researchers and practitioners have long recognized the demand of many retail items is proportional to the amount of inventory displayed recently two distinct types of inventory control models reflecting this relationship have appeared in the literature models in which the demand rate of an item is a function of the initial inventory level and those in which it is dependent on the instantaneous inventory level we present a comprehensive overview of this literature and demonstrate the equivalence of the two types of models through the use of a simple periodic review model an alternative approach to sensitivity analysis for inventory models with inventory level dependent demand is also presented

krutilla s legacy twenty first century challenges for environmental economics we all need heroes in academic life their ideas capture our imaginations convincing us that a set of problems is important often they are role models and mentors to young scholars certainly the academic enterprise would be less exciting and less productive without them this past year environmental economics lost john krutilla one of its founding fathers and a person i have always regarded as an academic hero few people have influenced environmental economics more than john it has now been fifteen years since his last major book was published bowes and krutilla and nearly forty years since the article conservation reconsidered that most environmental economists associate with him appeared in the aer a short recognition of his work prepared by resources for the future includes a comment by nobel laureate robert solow that captures the impact of this paper he observed that

insurance moral hazard and chemical use in agriculture this paper examines how crop insurance affects corn farmers fertilizer and pesticide use in the u s midwest crop insurance might be expected to affect chemical use because of moral hazard insured farmers may undertake riskier production than do uninsured farmers results suggest that insurance exerts considerable influence on corn farmers chemical use decisions those purchasing insurance applied significantly more nitrogen per acre 19 spent more on pesticides 21 and treated more acreage with both herbicides and insecticides 7 and 63 than did those not purchasing insurance these results suggest that both fertilizer and pesticides may be risk increasing inputs

tenants landlords and soil conservation it has long been argued that tenants tend to overexploit land but this conventional wisdom has been derived largely without consideration of landlords actions we examine what happens when landlords can invest in durable conservation measures in addition to choosing rental contract terms when tenants are risk neutral landlords overinvest in conservation under cash rental contracts but can achieve first best levels of output and protection against land degradation when conservation investment is combined with share rental when tenants are risk averse the first best is unattainable in this case conservation investment combined with share rental results in output levels below the first best while equilibrium conservation investment may be greater or less than the first best these results suggest that contract form and conservation investments are likely made simultaneously so that econometric studies of conservation practice adoption that treat rental status as exogenous are likely subject to bias

sustainable development challenges to profession of agricultural economics fundamentally sustainable development is a notion of discipline disciplining our current consumption this sense of intergenerational responsibility is a new political principle a virtue that must now guide economic growth the industrial world has already used so much of the planet s ecological capital that the sustainability of future life is in doubt that can t continue brundtland page 5

diffusion induced instability and pattern formation in infinite horizon recursive optimal control this paper develops local stability analysis for deterministic optimal control theory for recursive infinite horizon intertemporal optimization problems where there is a continuum of spatial sites and the state variable can diffuse over these sites we identify sufficient conditions for a type of local instability which emerges from the interaction of the discount rate on the future the curvature of the hamiltonian and the spatial features of the problem we call this phenomenon optimal diffusion induced instability odi we illustrate our analytical methods with three stylized applications the first application is the optimal management of spatially connected human dominated ecosystems the second and third applications are harvesting of spatially interconnected renewable resources jel classification c6 q2

a production inventory model in an imperfect production process abstract the paper develops a model to determine the optimal product reliability and production rate that achieves the biggest total integrated profit for an imperfect manufacturing process the basic assumption of the classical economic manufacturing quantity emq model is that all manufacturing items are of perfect quality the assumption is not true in practice most of the production system produces perfect and imperfect quality items in some cases the imperfect quality non conforming items are reworked at a cost to restore its quality to the original one rework cost may be reduced by improvements in product reliability i e decreasing in product reliability parameter lower value of product reliability parameter results in increase development cost of production and also smaller quantity of nonconforming products the unit production cost is a function of product reliability parameter and production rate as a result higher development cost increases unit production cost the problem of optimal planning work and rework processes belongs to the broad field of production inventory model which deals with all kinds of reuse processes in supply chains these processes aim to recover defective product items in such a way that they meet the quality level of good item the benefits from imperfect quality items are regaining the material and value added on defective items and improving the environment protection in this point of view a model is introduced here to guide a firm industry in addressing variable product reliability factor variable unit production cost and dynamic production rate for time varying demand the paper provides an optimal control formulation of the problem and develops necessary and sufficient conditions for optimality of the dynamic variables in this purpose the euler lagrange method is used to obtain optimal solutions for product reliability parameter and dynamic production rate finally numerical examples are given to illustrate the proposed model

an inventory model for deteriorating items with stock dependent demand rate abstract this paper discusses an inventory model with an inventory level dependent demand rate followed by a constant demand rate for items deteriorating at a constant rate where the terminal condition of zero inventory at the end of the scheduling period has been relaxed sensitivity of the decision variables to changes in the parameter values is examined and the effects of these changes on the optimal policy are discussed in brief

an inventory model with both stock dependent demand rate and stock dependent holding cost rate abstract in this paper we develop an inventory model under a stock dependent demand rate and stock dependent holding cost rate with relaxed terminal conditions shortages are allowed and partially backlogged in the model the purpose of this study is to determine the optimal order quantity and the ending inventory level such that the total profit per unit time is maximized for the retailer we first establish a proper model for a mathematical formulation then we develop several theoretical results and provide the decision maker with an algorithm to determine the optimal solution finally numerical examples are provided to illustrate the solution procedure and a sensitivity analysis of the optimal solution with respect to major parameters is carried out

the barely revealed preference behind road investment priorities an attempt is made to reveal the preference of decision makers within the regional norwegian public roads administration the order of priority assigned to the respective competing public road investment opportunities within the various counties provinces is studied by means of a rank order multinomial logit model explanatory variables used include cost benefit and a variety of attributes characterizing the individual investment projects although statistically significant cost and benefit appear to be of only marginal importance for the priorities set more weight is attached to cost than to benefit smaller projects are preferred to larger given the benefit cost ratio in general the models estimated are able to explain only a relatively small share of the priority setting made

the assumption of equal marginal utility of income how much does it matter abstract in most applied cost benefit analyses individual willingness to pay wtp is aggregated without using explicit welfare weights this can be justified by postulating a utilitarian social welfare function along with the assumption of equal marginal utility of income for all individuals however since marginal utility is a cardinal concept there is no generally accepted way to verify the plausibility of this latter assumption nor its empirical importance in this paper we use data from seven contingent valuation studies to illustrate that if one instead assumes equal marginal utility of the public good for all individuals aggregate monetary benefit estimates change dramatically

agricultural runoff as a nonpoint externality a theoretical development the purpose of this paper is to develop and explore a theory dealing with an important facet of agricultural runoff problems agricultural runoff is a nonpoint externality with notable implications for both research and policy a nonpoint externality exists whenever the externality contributions of individual economic agents cannot be practically measured by direct monitoring without monitoring regulations on emissions cannot be enforced and charges or subsidies cannot be assessed thus policies which are usually suggested for pollution abatement are not available there is great need for a theoretical base that can adequately capture these facts such a theory yields some important implications even before specific empirical applications the economic problem of agricultural runoff can be separated into three distinct categories first the sediment nutrients and chemicals removed by runoff represent a loss of resources to the individual farmer these costs are borne privately by farmers second if the discount rate of the individual farmer is greater than the social discount rate or if the farmer has a planning horizon which is shorter than society s the farmer will mine the soil resource at a rate which is more depletive than is socially optimal this is a temporal externality a third category involves the conservation of mass physical resources lost by the individual farm must appear elsewhere in the environment in sufficient quantities these resources are pollutants since water is the primary transport media for these resources it is water that is polluted by soil nutrients and agricultural chemicals this spatial externality has been the focus of much research here we intend to develop a theory for these issues to employ it to suggest a revised research methodology and to provide some important conclusions about alternative runoff policies only two of the three categories of agricultural runoff problems involve externalities and only the spatial externality is considered here

point nonpoint effluent trading with spatial heterogeneity potential earnings from permits sales may provide an incentive for farmers to accept water quality regulation we derive optimal adjustments of point nonpoint effluent trading ratios for heterogeneity in marginal environmental damage and degradation retention of the pollutant across locations in a watershed a simulation based on data from the kymi river valley finland indicates that farmers are the greatest suppliers of permits as expected but that gains from trading vary substantially some farmers may become net buyers of permits and thus net losers from regulation the benefits of effluent trading are distributed unevenly among point sources as well copyright 2008 oxford university press

the ideology of efficiency searching for a theory of policy analysis the potential pareto improvement criterion and other measures of economic efficiency do not pass the test of consistency and coherence within economic theory nor do such measures accord with what public decision makers seek in policy advice from economists such efficiency measures are nonetheless durable components of the ideology of economics in general and benefit cost analysis in particular the objectivity of the policy scientist has been confused with the objectivity of the science while economic efficiency has no claim to objectivity the policy scientist can be an objective analyst of policy choices

the effect of agricultural policies on land use and environmental quality in this paper i consider the environmental quality gains that may be achieved by reducing agricultural income supports a new methodology is developed to estimate land use shares in an application to wisconsin milk price support reductions result in shifts of marginal agricultural land to forest reducing soil erosion and providing off site water quality improvements the environmental benefits are estimated to be at least as large as the decreased welfare burden on consumers and taxpayers indicating a central role for environmental quality considerations in motivating policy reforms and a more efficient means of achieving the environmental quality goals of land retirement programs

valuing biodiversity for use in pharmaceutical research biodiversity prospecting has been touted as a mechanism for both discovering new pharmaceutical products and saving endangered ecosystems it is unclear what values may arise from such activities however evidence from transactions is incomplete and existing theoretical models are flawed we calculate an upper bound on the value of the marginal species even under favorable assumptions this bound is modest slightly modified assumptions lead to drastically lower estimates we extend our findings to the value of the marginal hectare of habitat and find that the incentives for habitat conservation generated by private pharmaceutical research are also at best very modest

a new analytical framework for the fertilization problem a novel control model for technical and economic analysis of fertilizer recommendations is based on liebig s law of the minimum mitscherlich s relative yield theory and the notions of yield plateau and soil fertility carry over the empirical model consists of a multistage separable programming specification which maximizes the discounted stream of net revenues subject to crop response and fertility carry over functions the model is applied to the wheat soybean cropping system in southern brazil it is found that while the optimal fertility target levels are within a small range of those determined by brazilian agronomists their maintenance recommendations could be substantially improved control relative yield yield plateau the analysis of yield response to fertilizers has been recently enriched by an original proposal of cate and nelson these soil scientists suggested that for agronomic purposes and for certain crops it may be convenient to postulate that the relationship between yield and major nutrients is a linear response and plateau lrp function they argued that this simplified specification is nonetheless capable of capturing the essential information of yield

economic impacts of marine reserves the importance of spatial behavior abstract marine biologists have shown virtually unqualified support for managing fisheries with marine reserves signifying a new resource management paradigm that recognizes the importance of spatial processes in exploited systems most modeling of reserves employs simplifying assumptions about the behavior of fishermen in response to spatial closures we show that a realistic depiction of fishermen behavior dramatically alters the conclusions about reserves we develop estimate and calibrate an integrated bioeconomic model of the sea urchin fishery in northern california and use it to simulate reserve policies our behavioral model shows how economic incentives determine both participation and location choices of fishermen we compare simulations with behavioral response to biological modeling that presumes that effort is spatially uniform and unresponsive to economic incentives we demonstrate that optimistic conclusions about reserves may be an artifact of simplifying assumptions that ignore economic behavior

choices without prices without apologies valuing is usually regarded as a process of compressing information about attributes into a single metric armed with this reduced form of compact information the consumer can consider a particular object with a particular price attached or implied and make an informed decision but the process of valuing is less straightforward than we ordinarily suppose when environmental goods and services become the object of information compaction it is possible that important information is lost we comment on the choice problem germane to environmental goods and services and challenge the presumption that environmental choices made without explicit pricing are inferior to those in which hypothetical valuation studies are undertaken

an inventory model with deteriorating items under inflation when a delay in payment is permissible abstract this study develops an inventory model for initial stock dependent consumption rate when a delay in payment is permissible in the inventory model shortages are not allowed the effect of the inflation rate deterioration rate initial stock dependent consumption rate and delay in payment are discussed in the study mathematical models are also derived under two different circumstances i e case i the credit period is less than or equal to the cycle time for settling the account and case ii the credit period is greater than the cycle time for settling the account besides expressions for an inventory system s total cost are derived for these two cases moreover a computational procedure and gino lasdon et al acm transactions mathematical software 4 1978 34 50 are proposed to obtain the optimal order size and cycle time the results can help managers determine the optimal total cost finally a numerical example demonstrates the applicability of the proposed model

an inventory model for deteriorating items with time proportional demand and shortages under inflation and time discounting this paper proposes a generalized dynamic programming model for inventory items with weibull distributed deterioration in this model the demand rate is assumed to be time proportional shortages are allowed and completely backordered and the effects of inflation and time value of money are taken into consideration the solutions of the model determine the optimal replenishment schedule over a finite planning horizon so that the present worth of total cost associated with the inventory system is minimized the proposed model permits variation in both the replenishment intervals and the service levels between order cycles as a result it generates a better solution than other optimization models having fixed order intervals and or fixed service levels the solution procedure is illustrated by two numerical examples and comparison with an existing model is carried out

project analysis as input to public debate environmental valuation versus physical unit indicators abstract monetary valuation of environmental change is useful if one aims to rank alternative projects according to some specific social welfare function however if the project analysis is intended as background information to a democratic debate the advantages of monetary valuation are less obvious this paper analyzes aggregation of information taking normative disagreement explicitly into account it is demonstrated that monetary valuation is not always more informative than a physical unit measure of environmental change

targeting incentives to reduce habitat fragmentation the fragmentation of wildlife habitat has long been recognized as a principal threat to terrestrial biodiversity in this paper we develop a theoretical model to analyze the spatial targeting of incentives for the restoration of forested landscapes when land quality is spatially heterogeneous and wildlife habitat can be enhanced by reducing fragmentation we consider a regulator who uses subsidies to encourage the conversion of private agricultural land to forest on a pre defined set of landscapes the regulator can observe land use choices but not the opportunity costs on individual land parcels the important insight to emerge from the theoretical analysis is that solutions at or near corners are a strong possibility on each landscape either none or all of the agricultural land should be converted to forest corner solutions are directly linked to the spatial process determining habitat benefits to verify the theoretical insight we present a simulation of the effects of incentive based policies on the spatial distribution of forests in south carolina the empirical methodology integrates an econometric model of land use change with gis based landscape simulations the empirical findings strongly support our conjecture regarding corner solutions and the optimal targeting policy is shown to produce substantial welfare gains over a spatially uniform incentive

analysis of deteriorating inventory production systems using a linear quadratic regulator we consider an inventory production system where items deteriorate at a constant rate the objective is to develop an optimal production policy that minimizes the cost associated with inventory and production rate the inventory problem is first modeled as a linear optimal control problem then linear quadratic regulator lqr technique is applied to the control problem in order to determine the optimal production policy examples are solved for three different demand functions sensitivity analysis is then conducted to study the effect of changing the cost parameters on the objective function

an economic ordering policy model for deteriorating items with time proportional demand abstract a t i s i inventory policy model for deteriorating items is presented in this paper the model is developed based on the assumptions that 1 demand rate is deterministic and linearly changes with time 2 deterioration rate is constant 3 planning horizon is finite and known and 4 replenishment periods are not equal the model is solved using a dynamic programming method the result is applicable to the case where the demand is either increasing or decreasing a numerical example is provided to illustrate the model and solution procedure

implicit prices of soil characteristics for farmland in iowa arguments have long persisted that purchasers pay too much for poor land i e less productive more erosive relative to the higher quality counterpart in other words purchasers are either irrational or poorly informed relative to the differences in land productivity between poor and good farmland similar arguments have been advanced concerning the willingness to pay rent on the part of tenant operators little empirical evidence exists to support or reject this hypothesis farmland appraisals are sometimes cited as evidence to support the contention but such empiricism may indicate more about the quality and biases of appraisers than about the behavior or efficient functioning of the farmland market resolution of this issue is extremely important to the formation of soil conservation policy designed to protect soil productivity irrational behavior on the part of land purchasers may lead one to infer that the market system is failing to recognize adequately the soil productivity consequences of soil erosion if this oversight consistently leads to excessive soil erosion from society s perspective then some form of government intervention may be necessary to protect the welfare of society assuming that such intervention is capable of correcting the market failure

contract choice in modern agriculture cash rent versus cropshare e conomists have expended enormous effort examining the rationale for various contractual arrangements in agriculture particularly sharecropping while economists have made considerable theoretical efforts to understand agricultural contracts few empirical studies have been undertaken the dearth of empirical analyses of agricultural contracts is particularly striking for modern western agriculture this is an important omission not only because the existing empirical work tends to focus on the question of efficiency but also because the theoretical models tend to examine contracts that bear little resemblance to those found in the united states today

2006 presidential address water markets in the west prices trading and contractual forms rising urban and environmental demand for water has created growing pressure to reallocatewaterfromtraditionalagriculturaluses theevolutionofwatermarketshas beenmorecomplicatedthanthoseforotherresources inthispaper wefirstexplainthese differences by examining water rights and regulatory issues second we place our research in the context of the economics literature on water marketing third we present new comprehensive data on prices and the extent nature and timing of water transfers across 12 western states from 1987 to 2005 we find that prices are higher for agriculture to urban trades versus within agriculture trades in part reflecting the differences in marginal values between the two uses prices for urban use are also growing relative to agricultural use markets are responding in that the number of agriculture to urban transactions is rising whereas the number of agriculture to agriculture transfers is not further there is a shift from using shortterm leases to using multiyear leases of water and permanent sales of water rights this pattern underscores the need to consider the amounts of water obligated over time rather than examining only annual flows in assessing the quantities of water traded as is the common practice in the literature considering water obligated over time termed committed water we find significantly more is transferred and the direction of trading is different than if the focus is on annual flows finally the data reveal considerable variation in water trading across the states jel q2 n5 l5 k3

production inventory models for a damageable item with variable demands and inventory costs in an imperfect production process in this paper economic production quantity epq models for breakable or deteriorating item are developed with variable demands being dependent on time or on hand stock here rate of production and holding cost are time dependent unit production cost is a function of both production reliability indicator and production rate set up cost is also partially production rate dependent the production process produces some imperfect quantities which are instantly reworked at a cost to bring back those units to the perfect ones the production process ultimately depends on both time and reliability indicator the models are formulated as optimal control problems and the total profit functions with effect of inflation and time value of money are expressed as finite integrals over the finite planning horizon the problems are solved using euler lagrange function based on variational calculus and newton raphson method to determine the optimal production reliability indicator r and then corresponding production rates and total profits in some cases results of the models for deteriorating item are obtained as particular cases from those of breakable item models similarly results of simple epq models without damageability are deduced as particular cases numerical experiments are performed to illustrate the models both numerically and graphically

uncoordinated agricultural and environmental policy making an application to irrigated agriculture in the west agriculture and the environment are linked by a mutual reliance on scarce resources and prevalent market distortions in this paper we examine the efficiency costs of policies that correct distortions in one sector while ignoring those in another the dual distortions of an environmental externality and water subsidies are studied in the context of irrigated agriculture in california the welfare costs associated with independent action by either a water agency or an environmental authority when that policy maker attempts to correct the respective market distortion without consideration of the distortion in the other market are estimated policies to correct the two distortions are found to be complementary under these conditions the independent correction of either distortion improves welfare by at least 118 per acre in most cases the simultaneous adoption of various second best policies further reduces welfare losses associated with these distortions

deterministic models of perishable inventory with stock dependent demand rate and nonlinear holding cost this paper deals with an extended eoq type inventory model for a perishable product where the demand rate is a function of the on hand inventory the traditional parameters of unit item cost and ordering cost are kept constant but the holding cost is treated as i a nonlinear function of the length of time for which the item is held in stock and ii a functional form of the amount of the on hand inventory the approximate optimal solution in both the cases are derived computational results are presented indicating the effects of nonlinearity in holding costs

an optimal replenishment policy for non instantaneous deteriorating items with stock dependent demand and partial backlogging abstract in this study we consider a problem of determining the optimal replenishment policy for non instantaneous deteriorating items with stock dependent demand in the model shortages are allowed and the backlogging rate is variable and dependent on the waiting time for the next replenishment the necessary and sufficient conditions of the existence and uniqueness of the optimal solution are shown as the special cases the results for the models with instantaneous or non instantaneous deterioration rate and with or without shortages are derived further we analytically identify the best circumstance among these special cases based on the minimum total relevant cost per unit time sensitivity analysis of the optimal solution with respect to major parameters is carried out finally four numerical examples are presented to demonstrate the developed model and the solution procedure

operations research in inventory management a review and critique the objectives of inventory management including the relevant related costs are examined in this paper a brief review of standard problems that have been effectively solved is presented however we point out that a serious gap exists between theory and practice in many organizations suggestions are made for bridging this gap finally a list is provided of a number of research problems whose implementable solution would have a major beneficial impact on the practice of inventory management

a model of regulated open access resource use abstract this paper develops a model of regulated open access resource exploitation the regulatory model assumes that regulators are goal oriented choosing target harvest levels according to a safe stock concept these harvest quotas are implemented by setting season lengths conditioned on the industry fishing capacity the industry enters until rents are dissipated conditioned on season length regulations harvest levels fishing capacity season length and biomass are determined jointly using parameter estimates from the long regulated north pacific halibut fishery predictions of these variables from the regulated open access model are compared to predictions that arise from the gordon model

bioeconomics of spatial exploitation in a patchy environment abstract this paper presents a model of renewable resource exploitation that incorporates both intertemporal dynamics and spatial movement the model combines the h s gordon vernon smith hypothesis of a rent dissipation process with ricardian notions that resources are exploited across space in a pattern dependent upon relative profitabilities the population structure is characterized in a manner consistent with modern biological ideas that stress patchiness heterogeneity and interconnections among and between patches generally we find the equilibrium patterns of biomass and effort across the system to be dependent upon bioeconomic conditions within each patch and the nature of the biological dispersal mechanism between patches we use simple examples to illustrate how the distribution of effort throughout the system reflects the heterogeneity and the spatial biological linkages

ambient taxes when polluters have multiple choices economic research on environmental policy design has largely been concerned with the merits of emissions based economic incentives e g emissions charges emissions reduction subsidies transferable discharge permits ambient based tax subsidy schemes have drawn considerable interest in nonpoint pollution literature as alternatives to emissions based instruments expanding especially on segerson s seminal article this article examines the optimal design and budget balancing properties of ambient tax subsidy schemes under more realistic assumptions about the dimensions of firms choice sets than prior research

an eoq model with state dependent demand rate we present an eoq type model in which the demand rate is a function of the inventory level the demand functions and holding cost functions considered are quite general in particular we focus on two types of demand rate functions a piecewise constant function and a family of exponential functions the paper includes analysis of the problem optimization and sensitivity analysis we also extend the model by adding randomness to the order sizes

inventory models with the demand rate dependent on stock and shortage levels this paper investigates an inventory system in which the demand rate during stockout periods differs from that during the in stock period by a given amount the previous analysis conducted in this area formulated the model as a cost minimization model this type of formulation will intentionally try to decrease demand by increasing the stockout period in order to decrease costs this paper appropriately considers the model as a profit maximization model and develops a closed form solution the model is then further generalized to incorporate the effect of stock level dependent demand rates and considers initial stock dependent demand as well as instantaneous stock dependent demand rates

demand promotion by upgradation under stock dependent demand situation a model the idea of demand promotion by upgrading the existing system of the selling centre has been modelled in this article the consumption rate is assumed to be dependent on the stock level the problem has been reduced to a maximizing problem the algorithmic approach for solving this maximizing problem is also provided objective is to maximize the net profit over a prescribed time an increasing convex upgradation cost is considered exponential upgradation cost has been considered for the numerical examples

the cold shiver of not giving enough on the social cost of recycling campaigns governments sometimes try to increase individuals contributions to public goods through appeals to consumer responsibility rather than by economic incentives for example in recycling campaigns using standard consumer theory one would hardly expect such campaigns to work at all but if consumers are motivated by norms appeals may work through changing consumers perception of the normrequirement however increasing voluntary contributions through appeals may come at a social cost the reason is that appeals work through imposing a heavier perceived responsibility on consumers this represents a welfare loss which is not necessarily outweighed by warm glow benefits

an optimal procurement policy for items with an inventory level dependent demand rate and fixed lifetime abstract this paper investigates an optimal procurement policy for items with an inventory level dependent demand rate and fixed lifetime the demand rate is assumed to be a function of current inventory level and each unit has its fixed expiry date so any units which remain unused by their expiry date are considered outdated and must be disposed of for the system presented a mathematical model and solution methodology were developed sensitivity of the decision variables to changes in the parameter values is examined and future research needs are discussed in brief

production and investment in natural resource industries there has been a recent tendency for economists to view natural resource scarcity as a diminishing threat to man s existence and his ability to produce an abundant supply of worldly goods see john v krutilla this change in view has emanated from the world s experience of the last few decades with technological development and the absence of any evidence that this rapid accumulation of technical knowledge will cease in some respects one might think that modern technology has removed the need for an economic theory of conservation temporal allocation of natural resources on the other hand conservation of natural resources can now be looked upon with less emotion since the dire consequences of too rapid exploitation are no longer a threat the question of conservation is thus a cold economic problem removed from many of its older value connotations there is indeed considerable effort taking place in the economics profession to fill this need for a quantitative economic theory of conservation however with one exception vernon smith focus has been limited to specific resources earlier works by lewis c gray and harold hotelling concerning the theory of the mine have recently been extended in numerous papers see r cummings and 0 burt richard l gordon anthony scott 1967 problems associated with petroleum production are considered in paul davidson and the fishery is considered in j a crutchfield and arnold zellner h scott gordon james quirk and vernon smith anthony scott 1955 and ralph turvey an extensive literature exists on the temporal allocation of groundwater two recent contributions are gardner brown and charles b mcguire and burt a logical problem has been encountered however in efforts to examine the optimum allocation of a natural resource over time without explicitly considering the rate of investment associated with resource use this difficulty stems from the long life of many capital items used in the process of exploiting the natural resource earlier studies have either tacitly or explicitly amortized costs of investment associated with resource use and proceeded as though all costs of production were essentially variable smith was the first to explicitly bring capital investment into a production model for natural resources and his work was followed by the authors where only exhaustible resources were considered more recently quirk and smith have introduced a dynamic model of the fishery in which capital investment is treated explicitly it seems then that there is a need for a comprehensive model for simultaneously optimizing the rate of resource use and investment in natural resource industries

stack them high let em fly lot sizing policies when inventories stimulate demand in some retail contexts stocking large quantities of inventory may not only improve service levels but can also stimulate demand for products having demand rates that increase with inventory levels we analyze the effect of stocking decisions on firm profitability to develop managerial insights regarding the structure of the optimal inventory policy and to understand how this policy differs from traditional approaches when inventories stimulate demand iteratively applying the standard economic order quantity eoq model by setting the demand rate parameter equal to the observed average demand rate in prior cycles yields an equilibrium order quantity that is robust to demand parameter misestimation but is suboptimal the profit maximizing policy orders larger quantities and can replenish inventory even before on hand stock fully depletes using an extension of a standard inventory dependent demand model from the literature we first provide a convenient characterization of products that require early replenishment we demonstrate that the optimal cycle time is largely governed by the conventional trade off between ordering and holding costs whereas the reorder point relates to a promotions oriented cost benefit perspective we show that the optimal policy yields significantly higher profits than cost based inventory policies underscoring the importance of profit driven inventory management

farm level economic analysis incorporating stochastic environmental risk assessment a farm level risk programming framework is presented which evaluates income environmental risk tradeoffs this framework uses a time series of environmental risk indices to incorporate the stochastic multiattribute characteristics of environmental outcomes associated with agricultural production practices the model is applied to a representative farm in the oklahoma panhandle region of the central high plains results indicate that expected income is sensitive to nitrate loading restrictions and relatively less sensitive to pesticide loading restrictions results also indicate that prescriptions derived using deterministic environmental risk measures may ignore significant probabilities of exceeding an environmental standard

limits to cba in uk and european environmental policy retrospects and future prospects this paper reviews the contemporary debate and the now long standing role of cba in uk and european environmental policy appraisal epa and looks forward to possible future applications the position taken is that despite its limitations cba still has an important part to play in epa however with the increasingly contested nature of environmental and related public policies and outcomes its role will become less prescriptive and its findings more constrained by social justice and ethical imperatives future cba is more likely to continue to flourish as a component in a wider policy analysis and decision support system whatever decision support system is eventually adopted its value will be judged on how well it aids real policymakers operating iteratively in the non linear real world political economy

a cooperative inventory policy with deteriorating items for a two echelon model a cooperative inventory policy between supplier and buyer is proposed unlike other studies we consider the case of deteriorating items and permit the completed back order in the problem we solve the problem without the condition of equal replenishments periods during a specified planning horizon and present a procedure to find the optimal solution a case is presented to demonstrate the application of the proposed approach the sensitivity analysis for a cooperation policy between supplier and buyer also are explored

a deterministic eoq model with delays in payments and price discount offers abstract it is the purpose of this paper to model the retailer s profit maximizing strategy when confronted with supplier s trade offer of credit and price discount on the purchase of merchandise generally retailers have to face many types of demands for different kinds of goods in real situation retailers have to correlate between the selling price and supplier s trade offer keeping in mind profit maximization strategy in the proposed model all increasing deterministic demands are discussed analytically numerically and graphically in the environment of permissible delay in payment and discount offer to the retailer

the economics of a public fund for environmental amenities a study of crp contracts the problem of targeting crp purchases to buy environmental amenities under productivity and environmental heterogeneity is considered gini coefficients and lorenz curves are used to measure the effectiveness of spending under alternative targeting criteria the environmental benefits considered are water erosion wind erosion surface water quality and wildlife habitat the three alternative targeting criteria examined include purchasing land according to i the benefit to cost ratio ii the level of benefits and iii the level of cost results indicate that the degree of variability and correlation determine the extent to which suboptimal targeting achieves a significant portion of available environmental benefits

optimal replenishment policies for non instantaneous deteriorating items with stock dependent demand abstract wu et al 2006 an optimal replenishment policy for non instantaneous deteriorating items with stock dependent demand and partial backlogging international journal of production economics 101 369 384 established an inventory model for non instantaneous deteriorating items with stock dependent demand and obtained the optimal replenishment policy in this paper we first amend wu et al s model by changing the objective to maximizing the total profit secondly we set a maximum inventory level in the model to reflect the facts that most retail outlets have limited shelf space thirdly we relax the restriction of zero ending inventory when shortages are not desirable we then establish the theoretical results and provide an algorithm to find the optimal solution finally we present some numerical examples to illustrate the results