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on Computational Economics |
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Issue of 2008‒08‒14
ten papers chosen by |
| By: | Jorge M. S. Valente (LIAAD, Faculdade de Economia, Universidade do Porto, Portugal); Maria R. A. Moreira (EDGE, Faculdade de Economia, Universidade do Porto, Portugal) |
| Abstract: | In this paper, we present greedy randomized dispatching heuristics for the single machine scheduling problem with quadratic earliness and tardiness costs, and no machine idle time. The several heuristic versions differ, on the one hand, on the strategies involved in the construction of the greedy randomized schedules. On the other hand, these versions also differ on whether they employ only a final improvement step, or perform a local search after each greedy randomized construction. The proposed heuristics were compared with existing procedures, as well as with optimum solutions for some instance sizes. The computational results show that the proposed procedures clearly outperform their underlying dispatching heuristic, and the best of these procedures provide results that are quite close to the optimum. The best of the proposed algorithms is the new recommended heuristic for large instances, as well as a suitable alternative to the best existing procedure for the larger of the middle size instances. |
| Keywords: | scheduling, single machine, early/tardy, quadratic penalties, greedy randomized dispatching rules |
| Date: | 2008–08 |
| URL: | http://d.repec.org/n?u=RePEc:por:fepwps:286&r=cmp |
| By: | Bouet, Antoine |
| Abstract: | "Trade liberalization is expected to act positively on world economic development and poverty alleviation, both of which have become high priorities of the international community. This emphasis explains why numerous studies have focused on assessing the expected benefits of trade liberalization on development. The main empirical tools for these assessments have been the use of spatial and nonspatial partial equilibrium models, gravity equations, and single- and multicountry computable general equilibrium models (CGEMs). Multicountry CGEMs, however, have produced strikingly divergent results. As demonstrated by recent studies, the associated increase in world welfare from full trade liberalization ranges from 0.2 to 3.1 percent—results that differ by a factor of 15! The objective of this study is to examine the efficiency of trade modeling in capturing the benefits from trade liberalization. It provides a survey of methodologies utilized to assess the impact of trade liberalization, putting an emphasis on multicountry CGEMs, and examines the extent to which such assessments diverge. The survey also demonstrates the benefits of “complementary analysis,” which utilizes different methodologies to study a specific topic. The report presents global modeling results using a general equilibrium model—the modeling international relations under applied general equilibrium (MIRAGE) model—the results of which are compared to those obtained in recent studies. Using the MIRAGE model,1 full trade liberalization is estimated to increase world real income by US$100 billion (+0.33 percent) after 10 years of implementation. This trade reform would be development-friendly, as it entails a larger growth rate of real income for developing countries and especially for least-developed countries." "Authors' Abstract |
| Keywords: | Trade modeling, Poverty alleviation, Assessment, trade liberalization, Computable general equilibrium (CGE) modeling, Development, agricultural sector, Agricultural prices, Globalization, |
| Date: | 2008 |
| URL: | http://d.repec.org/n?u=RePEc:fpr:fprevi:8&r=cmp |
| By: | Hayakawa, Kazunobu; Chang, Kuo-I |
| Abstract: | Abstract: By means of a GTAP based-CGE model, we investigate the impact of the elimination of import tariffs and non-tariff policy barriers (NTPBs) on agricultural trade towards East Asian FTAs. To do that, we first measure the NTPBs by employing a widely-used method derived from the literature on border effects. Next, by adding into the GTAP database our estimates on the NTPBs, which the original GTAP database by its nature does not succeed in incorporating, we compute the impact of the entire elimination of policy barriers (the complete reduction of import tariffs and of NTPBs) on GDP. |
| Keywords: | Border barrier, Agricultural trade, GTAP, East Asia |
| JEL: | F13 F14 Q17 |
| Date: | 2008–06 |
| URL: | http://d.repec.org/n?u=RePEc:jet:dpaper:dpaper160&r=cmp |
| By: | Varsanyi, Zoltan |
| Abstract: | In this paper I present a method for the simulation of the default of such loans that have two important properties: they are seasoned – maybe even being at different points of the seasoning curve – and they evolve in an asset-value based framework. This latter model allows us to introduce correlation between the loan defaults. Although these two features are widely considered in modelling, linking them into one single (simulation) framework might not be that common. However, the most important merit of this paper is showing a fast and accurate simulation algorithm for the asset values. |
| Keywords: | credit risk; simulation |
| JEL: | C15 |
| Date: | 2008–08 |
| URL: | http://d.repec.org/n?u=RePEc:pra:mprapa:9918&r=cmp |
| By: | Breisinger, Clemens; Diao, Xinshen; Thurlow, James; Al-Hassan, Ramatu M. |
| Abstract: | "This paper has been prepared in support of the Comprehensive Africa Agriculture Development Program (CAADP) roundtable in Ghana. The study also takes a fresh perspective on the role of agriculture for development in light of the global food crisis. It addresses two main questions: what are the impacts of Green-revolution type agricultural growth to reach the CAADP goal in Ghana? Given the large investments required to achieve such productivity-led growth, what is the sector's contribution to the overall economy? Results from the dynamic computable general equilibrium model suggest that by closing the existing yield gaps in crop production and supporting essential growth in the livestock sector Ghana can achieve CAADP's 6 percent growth target. In this process, agriculture supports the rest of the economy through substantial and largely invisible monetary transfers to the nonagricultural sectors, which are primarily driven by the reduction of domestic food prices. Thus, CAADP growth benefits both rural and urban households, and reduces poverty by more than half within 10 years. However, widening regional disparities between the North and the rest of Ghana will increasingly pose a challenge for the development. Additional measures more targeted towards generating growth in the lagging North will be necessary to bridge the income gap and reach Ghana's poorest of the poor." from Author's Abstract |
| Keywords: | Agriculture, Poverty, Computable general equilibrium (CGE), Development strategies, Comprehensive Africa Agriculture Development Program (CAADP), |
| Date: | 2008 |
| URL: | http://d.repec.org/n?u=RePEc:fpr:ifprid:784&r=cmp |
| By: | Giang , Thanh Long; Pfau, Wade Donald |
| Abstract: | By using the Vietnam Household Living Standard Survey in 2004, this paper seeks to quantify the potential role and impacts of a social pension scheme for reducing elderly poverty in Vietnam. We simulate how the poverty rate, poverty gap, and poverty severity of the elderly would have been changed in the counterfactual situation that such a scheme had been introduced to Vietnam in the past. We consider a number of categorical targeting groups of elderly people along with various transfer parameters to assess the impacts of the scheme on social welfare. We find that, depending on the characteristics of the social pension, there would be beneficial poverty reductions, but also large leakages to the non-poor people. For a variety of measures, our results suggest that targeting the elderly in rural areas might be the most effective use of limited resources. Also, simulations for different budgetary constraints show that, even with limited budgeting, a social pension scheme would significantly reduce poverty incidence for the elderly. For example, the elderly poverty gap could be reduced by almost 60 percent with a program that costs one percent of GDP. |
| Keywords: | aging; poverty; social pensions; Vietnam |
| JEL: | H55 I38 I32 |
| Date: | 2008 |
| URL: | http://d.repec.org/n?u=RePEc:pra:mprapa:9930&r=cmp |
| By: | Álvaro Andrés PERDOMO STRAUCH |
| Abstract: | Cuando se llevan a cabo discusiones de política económica es importante utilizar herramientas provenientes de la teoría económica que permitan adelantar con mayor solidez las argumentaciones. Igualmente, cuando se estudian modelos de teoría económica es interesante incorporar dentro de estos modelos cifras de la vida real para ver cuál es el comportamiento de los mismos ante diferentes choques o medidas de política económica. En varias ocasiones ninguna de las dos actividades anteriormente reseñadas es llevada a cabo porque no se cuenta con la experiencia y/o con el tiempo suficiente para desarrollar las herramientas adecuadas que permitan adelantar dichas actividades. En este documento se va a presentar un modelo estándar de equilibrio general computable que pueda ser utilizado como insumo para adelantar diferentes discusiones de política económica1. |
| Date: | 2008–07–31 |
| URL: | http://d.repec.org/n?u=RePEc:col:000118:004943&r=cmp |
| By: | Jean-Pierre Cling (DIAL); Mohamed Ali Marouani (Université Paris1-Sorbonne/IEDES, DIAL et ERF); Mireille Razafindrakoto (DIAL, IRD, Paris); Anne-Sophie Robilliard (DIAL, IRD, Paris); François Roubaud (DIAL, IRD, Paris) |
| Abstract: | (english) The strong growth of the Vietnamese economy over the last two decades has brought about sweeping economic and social changes. In particular, there has been a sharp downturn in poverty along with an upturn in social inequalities (albeit not as sharp as in China). This makes the question of the distributional impact of the country’s WTO accession (January 2007) a particularly keen one. The first simulations made using our micro-simulation model point to mainly four types of redistributive effects induced by WTO membership: job gains (especially industrial jobs), growth in real wages, reduction in gender inequalities, and increase in inequalities between rural and urban areas (but slight drop in overall inequalities). Our findings demonstrate the importance of flanking measures to accompany WTO accession and making the most the opportunities that arise, especially in the area of training, domestic migration, regional policies and assistance to wage earners affected by restructuring. _________________________________ (français) La forte croissance de l’économie vietnamienne au cours des deux dernières décennies s’est accompagnée de profondes transformations économiques et sociales. En particulier, on a observé une forte réduction de la pauvreté, accompagnée d’une progression des inégalités sociales (quoique moins accentuée qu’en Chine). Dans ce contexte, la question de l’impact distributif de l’adhésion à l’OMC intervenue en janvier 2007 se pose avec acuité. Les premières simulations effectuées à l’aide de notre modèle de micro-simulation comptable indiquent que l’adhésion à l’OMC aura principalement quatre types d’effets redistributifs : gains d’emplois (en particulier industriels) ; croissance des salaires réels ; réduction des inégalités de genre ; progression des inégalités entre zones rurales/urbaines (mais tassement des inégalités globales). Nos résultats montrent l’importance de prendre des mesures pour accompagner l’entrée à l’OMC et saisir les opportunités offertes, en particulier dans le domaine de la formation, des migrations internes, des politiques régionales et de l’aide aux salariés touchés par les restructurations. |
| Keywords: | International Trade; WTO; Labour; Inequalities; Vietnam, Commerce international; OMC; Emploi; Inégalités; Vietnam. |
| JEL: | F16 |
| Date: | 2008–08 |
| URL: | http://d.repec.org/n?u=RePEc:dia:wpaper:dt200803&r=cmp |
| By: | Lang, N.A.; Moonen, J.M.; Srour, F.J.; Zuidwijk, R.A. (Erasmus Research Institute of Management (ERIM), RSM Erasmus University) |
| Abstract: | Based on a literature survey, we aim to answer our main question: “How should we plan and execute logistics in supply chains that aim to meet today’s requirements, and how can we support such planning and execution using IT?†Today’s requirements in supply chains include inter-organizational collaboration and more responsive and tailored supply to meet specific demand. Enterprise systems fall short in meeting these requirements The focus of planning and execution systems should move towards an inter-enterprise and event-driven mode. Inter-organizational systems may support planning going from supporting information exchange and henceforth enable synchronized planning within the organizations towards the capability to do network planning based on available information throughout the network. We provide a framework for planning systems, constituting a rich landscape of possible configurations, where the centralized and fully decentralized approaches are two extremes. We define and discuss agent based systems and in particular multi agent systems (MAS). We emphasize the issue of the role of MAS coordination architectures, and then explain that transportation is, next to production, an important domain in which MAS can and actually are applied. However, implementation is not widespread and some implementation issues are explored. In this manner, we conclude that planning problems in transportation have characteristics that comply with the specific capabilities of agent systems. In particular, these systems are capable to deal with inter-organizational and event-driven planning settings, hence meeting today’s requirements in supply chain planning and execution. |
| Keywords: | supply chain;multi agent systems;MAS |
| Date: | 2008–07–31 |
| URL: | http://d.repec.org/n?u=RePEc:dgr:eureri:1765012902&r=cmp |
| By: | Arthur Huang; David Levinson (Nexus (Networks, Economics, and Urban Systems) Research Group, Department of Civil Engineering, University of Minnesota) |
| Abstract: | Clusters of business locations, which considerably impact daily activities, have been promi- nent phenomena. Yet the question of how and why Þrms cluster in certain areas has not been sufÞciently studied. This paper investigates the emergence of clusters of business locations on a supply chain network comprised of suppliers, retailers, and, consumers. Krugman (1996) argued that urban concentration involved a tension between the ÒcentripetalÓ and the Òcen- trifugalÓ forces. Based on that notion, this research proposes an agent-based model of retail- ersÕ location choice in a market of homogeneous products. In this game, retailers endeavor to maximize their proÞts by changing locations. RetailersÕ distribution patterns are measured by entropy and cluster density. Simulation results reveal that as more retailers engage in the game, clusters autonomously emerge and the entropy of clusters increases. Once retailers exceed a certain number, average density of clusters begins to decline; all discrete clusters gradually merge to a large cluster, spreading out uniformly. This research thus Þnds that the centripetal force attracts retailers to supplier locations; with even more retailers entering the market, the centrifugal force disperses them. The sensitivity results on model parameters and consumersÕ demand elasticity are also discussed. |
| Keywords: | clustering, supply chain network, location choice, distribution pattern |
| JEL: | R41 R48 D63 |
| Date: | 2008 |
| URL: | http://d.repec.org/n?u=RePEc:nex:wpaper:cluster&r=cmp |