the joint economic lot size problem a review abstract this article reviews lot size models which focus on coordinated inventory replenishment decisions between buyer and vendor and their impact on the performance of the supply chain these so called joint economic lot size jels models determine order production and shipment quantities from the perspective of the supply chain with the objective of minimizing total system costs this paper first describes the problem studied introduces the methodology of the review and presents a descriptive analysis of the selected papers subsequently papers are categorized and analyzed with respect to their contribution to the coordination of different echelons in the supply chain finally the review highlights gaps in the existing literature and suggests interesting areas for future research

the spatial mismatch hypothesis what has the evidence shown this paper reviews 20 years worth of empirical evidence on the spatial mismatch hypothesis after briefly surveying the relevant models from urban and labour economics and recent trends in employment and population suburbanisation the empirical evidence on spatial effects is examined this literature includes evidence on the effects of residential segregation residential suburbanisation and employment suburbanisation and direct measures of access such as travel times the most recent evidence suggests that spatial mismatch is relevant for explaining black white employment differences though the magnitudes of these effects remain unclear

intra metropolitan variation in earnings and labor market discrimination an econometric analysis of the atlanta labor market one of the most enduring debates concerning racial differences in earnings is whether housing segregation within metropolitan areas adversely affects the employment opportunities of urban blacks two possible negative effects can be listed first the decentralization of lower skilled jobs combined with the suburban residential exclusion of low income households may have caused wage rates within the suburban labor market to rise above those paid within the central city if this is the case and if housing market discrimination restricts the relative ability of blacks to offer their labor supply to suburban employers then at least part of the racial difference in earnings can be attributed to housing segregation second housing segregation may cause private sector labor market discrimination to be more severe within the central city in comparison to suburban areas as suggested by becker s taste for discriminating model 3 a relatively large black labor supply within the central city may require a lower black to white earnings ratio in order to induce prejudiced employers to hire large numbers of black workers with the workforce of most central cities becoming increasingly black this may be an important factor in explaining racial differences in earnings surprisingly while variation in discrimination among occupations regions industries and sectors have been examined in some detail spatial differences in discrimination between the central city and suburbs have largely escaped analysis in this paper the earnings of private sector workers broken down by occupation race and sex are compared between worksite areas encompassing the metropolitan area of atlanta georgia while an extensive literature can be found on interregional differences in earnings little evidence exists on the spatial variation in wage rates within metropolitan regions in fact virtually nothing has been done on this issue since the classic study of the chicago labor market by rees and shultz 19

assessing holistic economic value for multifunctional agriculture in the us abstract this study used contingent valuation method to shed light on public preferences on the multifunctional roles of the us agriculture and to present a holistic estimate of the economic value of the nonmarket goods and services of us agriculture contingent valuation survey instrument was administered to a sample composed from the ipsos web based panel fishbein s model of reasoned behavior and mediation hypothesis were combined to model the relationship between wtp behavioral intentions and sets of explanatory variables including attitudes perceived attributes about family farms farmland preservation programs government involvement in agricultural markets and ecological state of our world and socio demographic profiles results show that while exerting a highly significant impact on wtp attitudes mediate the effects of the attribute variables on wtp i e the attributes influence wtp directly as well as indirectly through attitudes the estimated mean wtp was 515 per taxpayer annually aggregating individual wtps across the us taxpayers above 20 years old produces 105 billion representing a crude estimate of the economic value that the us consumers place on the multifunctional roles of us agriculture

space and unemployment the labor market effects of spatial mismatch the aim of this article is to analyze the effects of housing discrimination on the wages and unemployment rates of black workers the unemployment effect is first analyzed using a simple minimum wage model an efficiency wage model is then adopted in order to endogenize both unemployment and wages under both models suburban housing discrimination leads to a higher unemployment rate for blacks in the central city than in the suburbs under the efficiency wage model black wages are also lower in the center the analysis thus generates a link between unemployment and a seemingly unrelated phenomenon racial discrimination in the housing market

an alternative approach to the analysis of wage differentials a key question in many studies of male female or black white wage differentials is how much of the differential can be explained by economic factors and how much remains unexplained the unexplained portion is then ascribed to discrimination since oaxaca 17 first formalized this decomposition the residual difference methodology has been the dominant methodology utilized in empirical studies of wage differentials 4 7 8 10 15 18 but recently the validity of the assumptions underlying the residual difference methodology have been called into question by butler 5 6 in this paper the theoretical underpinnings of the residual difference methodology are reexamined and an alternative theoretical framework for this methodology is suggested the new framework overcomes the shortcomings inherent in oaxaca s specification of the model and therefore provides a sound theoretical foundation for the residual difference decomposition

male sub metropolitan black white wage gaps new evidence for the 1980s this study analyses trends in us male black white earnings gaps by sub metropolitan residence large suburban earnings gaps existed in 1979 however central city gaps exhibited the largest increases during the 1980s the increases are decomposed into changes in measurable characteristics changes in the prices of measurable characteristics changes in discrimination and or unobservable skills and changes in white earnings inequality changes in measured characteristics and their prices and changes in inequality account for little of the increases in central city gaps either labour market discrimination worsened or racial differences in unobservable skills widened a review of the literature suggests that this paper s evidence is more consistent with a worsening in discrimination

the single vendor single buyer integrated production inventory model with a generalised policy abstract this note considers a more general type of policy for the single vendor single buyer integrated production inventory model than has hitherto been presented based on successive shipments to the buyer within a single production batch increasing by a fixed factor

black residential centralization and the spatial mismatch hypothesis abstract black residential centralization is found to be an important determinant of black employment status when estimated across metropolitan areas mas to avoid neighborhood selection the effects are greatest in large mas for the young and elderly and for individuals with less than a college education instrumental variable iv estimates support ordinary least squares ols results black residential centralization can account for 48 62 of the black white employment differential among 18 30 year olds living in large mas when estimated together black residential centralization job centralization and segregation all have large effects but the effects of black centralization and job centralization are considerably larger

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

an empirical investigation of intraurban wage gradients abstract intraurban wage gradients have received little attention in the urban literature but have been shown theoretically to be important indicators of the spatial characteristics of urban economic activity this study examines the spatial distribution of wages of five groups of municipal public employees in the chicago smsa negative wage gradients significant at the 0 05 level are found for four of the five labor groups results show that monthly wages decrease on average as much as 24 per additional mile from the city center

intraurban wage gradients evidence by race gender occupational class and sector abstract a general functional form is used to estimate intraurban wage gradients for various groups of workers with 1980 data from the philadelphia detroit and boston metropolitan areas as predicted by the standard monocentric model of urban land use the following results are obtained for most groups of white workers negative and statistically significant wage gradients steeper wage gradients for higher wage earners and an increase in the steepness of wage gradients as the cbd is approached positive wage gradients are not found for black workers despite the fact that suburban employers hire large numbers of these workers who reside within the central city this result is taken as support for the hypothesis that blacks have been disadvantaged by job suburbanization and continued housing market segregation

residential segregation and the economic status of black workers new evidence for an old debate abstract scholars have long debated whether ghetto residence lowers the earnings of blacks most empirical studies on this question have been flawed because they have not considered the simultaneous effects of choices of work and residence locations and the effects of intrametropolitan variation in rents and wages this paper estimates a revealed preference model of intraurban location with data from the 1980 public use microdata sample for cleveland detroit and philadelphia to test whether black male household heads who are employed full time year round are less likely than whites to live and work at their best locations we measure the wages rents and commuting costs associated with each possible job residence location combination in these cities for each person given their job qualifications and their housing needs a revealed preference approach is used to evaluate the economic welfare of individuals at each possible location and then compare the actual distribution of work and residence locations by race with the welfare maximizing distribution the divergence in these distributions by race measures the economic effects for employed black male household heads of residential segregation in ghettos we find that the economic status of blacks can be improved significantly by changing their intrametropolitan job locations surprisingly this conclusion holds regardless of whether or not blacks keep their current residential locations while changes in residential locations can improve the economic status of blacks relative to whites by decreasing commuting and or the cost of housing such residential changes do not significantly alter the physical accessibility of better paying jobs

urban diversity and economic growth at the risk of some simplification it is possible to identify four periods of intense study of cities by economists each of these has led to an increased understanding of the economics of urban areas and the unique role played by cities in the modem economy the first of these periods occurred in the decade after world war i only about ten years after the truck revolutionized the transport of goods within urban areas this period included the first systematic empirical analysis of the forces affecting the location of firms and households within cities robert murray haig 1926 and a number of other microeconomists at columbia analyzed the spatial pattems of manufacturing activity in lower manhattan and in the rest of new york city haig jmd his colleagues devoted considerable attention to where things belong in an urban area p 402 providing the first systematic economic analysis of urban spatial structure for example they analyzed the garment industry concluding that it was destined by nature to disperse north of 14th street and predicting that it would follow the estabhshed spatial pattem of the cooperage barrelmaking industry standardization in size and quality of barrels had meant that identical barrels could be made throughout the new york metropolitan area even in new jersey and the introduction of the truck meant that they could be transported cheaply throughout the region and exported the second of these periods though not in chronological order began in the mid 1960s it formalized many of the insights about location incentives within urban areas which had been uncovered a half century before mixed them with the logic of heinrich von thunen s 1826 ancient theories about agricultural crops and land values and applied them to the hotisehold sector the works of william alonso 1964

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

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

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