Autonomous Control Approach for Local Search

Date du colloque : 09/2009International audienceWe propose here an approach for the autonomous control of a local search algorithm, which has several moves operators, whose efficiency can be diverse and whose application is adjusted according to the observation of the current status of search, in order to adapt to the balance between exploitation and exploration of search space

Une approche de contrôle autonome pour la recherche locale

Les algorithmes de recherche locale s\u27appuient principalement sur la notion de voisinage pour visiter des configurations successives au sein de l\u27espace de recherche, guidés également par les possibles stratégies de choix de ces voisins. Ces mouvements de proche en proche doivent être soigneusement contrôlés si l\u27on souhaite garantir une exploration suffisante de l\u27espace de recherche, ainsi que la possibilité de converger vers une solution. Des alternatives aux approches classiques ont été proposées afin d\u27envisager des voisinages plus complexes ou même de gérer simultanément plusieurs voisinages. Toutefois, biais souvent incontournable des métaheuristiques, ces approches induisent de nouveaux paramètres ou des heuristiques ad-hoc, dont l\u27importance sur les performances est grande mais le réglage délicat. nous proposons ici, une approche de contrôle autonome pour un algorithme de recherche locale qui disposera de plusieurs opérateurs de mouvements, dont l\u27efficacité peut être diverse, et dont l\u27application respective sera ajustée en fonction de l\u27observation de l\u27état courant de la recherche, dans le but de s\u27adapter aux exigences d\u27équilibrage entre exploitation et exploration de l\u27espace des configurations. nous définissons pour cela une nouvelle mesure de diversité, couplée à une mesure classique de qualité, qui autorise ainsi un contrôle simple de l\u27algorithme. Notre approche est finalement évaluée sur le problème classique d\u27affectation quadratique (QAP), obtenant des résultats prometteurs

Analisis Keunggulan Kompetitif Ubi Kayu Terhadap Jagung Dan Kedelai Di Kabupaten Lampung Tengah

Cassava is widely developed in Lampung province, because of high adaptability, easily cultivated, smallest risk of failure, and high price. The objective of the study is to analyze on-farm competitive advantage of casava farming system compared to maize and soybean farming systems. The activities were conducted at Central Lampung District from April 2012 to February 2013. The primary data were obtained from 90 farmers as main respondents through structured survey with direct interviews using structural questionnair. Secondary data were obtained from the office of relevant agencies and Statistic of Lampung Province. Financial analysis and competitive advantage analysis were exercised to measure the competitive advantage of cassava with respect to other secondary crops. The results showed that cassava farming more profitable than maize and soybean on farm income of Rp.21.109.000/ha and R/C of 2,91 compared to maize on farm income Rp.15.935.000 and R/C of 2,01 and soybean farm income of Rp.5.187.800/ha and R/C of 1,48. Cassava farming system will be competitive compared to maize and soybean farming on the productivity at least 34.567 kg/ha and 20,788 kg/ha and cassava price at least IDR 654/kg and IDR 394/kg

A Tabu Search Algorithm with Direct Representation for Strip Packing

This paper introduces a new tabu search algorithm for a two-dimensional (2D) Strip Packing Problem (2D-SPP). It integrates several key features: A direct representation of the problem, a satisfaction-based solving scheme, two different complementary neighborhoods, a diversification mechanism and a particular tabu structure. The representation allows inexpensive basic operations. The solving scheme considers the 2D-SPP as a succession of satisfaction problems. The goal of the combination of two neighborhoods is (to try) to reduce the height of the packing while avoiding solutions with (hard to fill) tall and thin wasted spaces. Diversification relies on a set of historically “interesting” packings. The tabu structure avoids visiting similar packings. To assess the proposed approach, experimental results are shown on a set of well-known benchmark instances and compared with previously reported tabu search algorithms as well as the best performing algorithms

Pareto Autonomous Local Search

This paper presents a study for the dynamic selection of operators in a local search process. The main purpose is to propose a generic autonomous local search method which manages operator selection from a set of available operators, built on neighborhood relations and neighbor selection functions, using the concept of Pareto dominance with respect to quality and diversity. The latter is measured using two different metrics. This control method is implemented using the Comet language in order to be easily introduced in various constraint local search algorithms. Focusing on permutation-based problems, experimental results are provided for the QAP and ATSP to assess the method’s effectiveness

Advances in Pneumatic-Controlled High-Lift Systems Through Pulsed Blowing

Circulation Control technologies have been around for 65 years, and have been successfully demonstrated in laboratories and flight vehicles alike. Yet there are few production aircraft flying today that implement these advances. Circulation Control techniques may have been overlooked due to perceived unfavorable trade offs of mass flow, pitching moment, cruise drag, noise, etc. Improvements in certain aspects of Circulation Control technology are the focus of this paper. This report will describe airfoil and blown high lift concepts that also address cruise drag reduction and reductions in mass flow through the use of pulsed pneumatic blowing on a Coanda surface. Pulsed concepts demonstrate significant reductions in mass flow requirements for Circulation Control, as well as cruise drag concepts that equal or exceed conventional airfoil systems

The David R. Tillinghast Lecture - What's Source Got to Do with it - Source Rules and U.S. International Taxation

Arguably, the largest problem in international income taxation is the proper treatment of income that is subject to the legitimate taxing claims of two or more countries. A source country's jurisdiction to tax foreign persons is limited to income earned within the source country's borders. Under current international norms, however, the taxpayer's residence country is required to accommodate the source country's taxing right by employing a foreign tax credit or by exempting foreign source income. Thus, source taxation is at once geographically constrained, but also jurisdictionally superior to residence taxation. These principles require that international income be divided and accounted for between countries according to criteria that relate income and deductions to geographic locations. To be specific, the consequence of geographically limited source taxation and overlapping, but secondary, residence taxation is that the source of income must be determined so that the right to tax can be assigned. In this sense, the concept of "source" is at the heart of international taxation. We argue in Section II that the right of source countries to tax foreign persons on their source country income has a robust normative foundation. By contrast, we find that source rules that serve as instruments for implementing source taxing jurisdiction and effecting residence country accommodation of source country taxation are surprisingly lacking in normative content. Thus, if timing of income and expense recognition is the Achilles heel of a purely domestic income tax system, the source of income and expense is an equally weak link in the international tax rules. Because no clear economic or equitable principles guide the formulation of rules to divide income and expense by geographic origin, the construction of these rules has been a significantly arbitrary exercise. Why is it important to get source and source taxation rules right? One reason is to protect the U.S. income tax base. Today, sophisticated taxpayer planning exploits weaknesses in the income tax regimes of the United States, as well as other developed countries, by taking advantage of (1) the evolution of economic activity in the developed world toward value-added services and intangible assets, (2)increased flexibility in locating tangible economic functions and intangible assets, (3) technological and communications advances that challenge the ability of countries to impose tax at source, (4) substantial innovations in the structuring of financial assets, and (5) the continued availability of low-tax countries that sometimes erect enforcement obstacles in the form of confidentiality restrictions. Although source taxation plays a vital role in the U.S. international income tax regime by protecting the U.S. income tax base, there has not been a systematic reexamination of U.S. source taxation rules since 1966. In that year, the Foreign Investors Tax Act of 19669 reduced the "force of attraction," net-basis taxation of. foreign investors' U.S. investment income in order to encourage investment of foreign capital in the United States to relieve a chronic balance of payments deficit in the early 1960's. Since that time, however, the balance of payments has ceased to be a concern and the United States has become a net importer of foreign direct as well as portfolio investment." A reexamination of U.S. source taxation rules is long overdue. A fresh consideration of source rules and source taxation also is timely because international income is an increasingly important element of the U.S. economy. The 2002 Economic Report of the President identifies two directly relevant trends: (1) increased globalization and location of economic activity according to advantageous terms of trade, and (2) a related evolution of U.S. economic activity toward highly mobile value-added services and intangible products (and tangible products with embedded intangible value). Indeed, total trade (measured as imports plus exports) increased from 16% of gross domestic product in 1975 to 26% in 2000. In our reconsideration of source taxation and the related rules that assign geographic source to items of income and expense, we assume that source taxation will continue to have primacy over residence taxation, except to the extent that treaties provide otherwise, and that international double taxation issues will continue to be addressed through unilateral and bilateral measures. Moreover, we assume that nations will not forgo self-interest in any significant way when they undertake such unilateral and bilateral measures. In short, we believe that reconsideration of source taxation and source rules must be constrained by the premise that nations will continue to approach international taxation issues within a structure that does not depart radically from current international norms. In particular, we see nothing to suggest any reasonable prospect for nations, including particularly the United States, joining in multilateral approaches that deal with sourcing and double taxation of income. In Section II we set out the theoretical justification for taxing foreign persons who earn both active and passive income by making use of the U.S. physical, legal, and/or economic infrastructure. We evaluate alternative approaches to imposing tax at source on U.S. business activity and conclude that taxation of net business income at the same progressive rates applicable to residents is the best alternative. We also evaluate the role of fairness considerations in source taxation and conclude that they do not bear significantly, except that fairness would not necessarily be enhanced by eliminating taxation at source. In Section III we summarize the U.S. tax policy objectives regarding international income and develop criteria for U.S. source taxation of foreign persons on income from their U.S. businesses and portfolio investments. U.S. source taxation of nonresidents is important to preserve the perceived legitimacy of residence-based taxation with respect to similar activities carried on by U.S. persons. Specifically, we suggest that a need for "perceived parity" requires a level of effective source taxation comparable to that imposed on residents engaged in the same activity. Moreover, source taxation is important to prevent residents from having an incentive to become nonresidents and earn U.S. income. As a country whose residents invest abroad, the United States also has strong reasons to resist excessive or discriminatory taxation of nonresidents. We suggest in Section III, however, that the existing treaty concept of nondiscrimination does not adequately recognize the ways in which differential taxation of owners of U.S. business entities should be taken into account in evaluating whether a tax rule results in discrimination in fact. Finally, in Section III we undertake an extended review of the impact of source taxation's geographical limitations on the administration and enforcement of source tax rules. We observe that withholding at source helps overcome limitations on jurisdiction to enforce. Adoption of the qualified intermediary rules extends the reach of this regime outside the United States to the financial institution dealing directly with the nonresident taxpayer. Notwithstanding these improvements in enforcement mechanisms, we conclude that administration of source taxation would be less burdensome and enforcement less problematic if exceptions from source taxation were adopted only by treaty. We also conclude that enforcement of netbasis taxation at source on a remote seller (of goods, intangibles, or services) without a direct physical presence is extremely difficult in the absence of a treaty. In Section IV we consider the implications for certain selected U.S. source rules of the criteria developed in Section III. We disclaim, however, any attempt at a comprehensive critique of U.S. source rules. Instead, we provide illustrative examples of our analytical approach by considering the consequences of applying the Section III criteria to the U.S. sourcing rules for services and royalties. We also discuss the implications of residence-based source rules. While we do not evaluate the policy wisdom of exempting income from foreign owned capital, in the light of changes in the U.S. mechanisms for enforcing source taxation of investment income, we argue that now is an appropriate time to consider whether reciprocal treaty exemptions should replace the current U.S. unilateral exemption of portfolio interest and gains on the sale of large stock holdings. We also suggest consideration of developing mechanisms to tax at source income from U.S. sales of goods and services by remote sellers, subject to relief by treaty. In Section V, we contrast the source rules used for source taxation with the source rules used for the foreign tax credit limitation. We conclude that the two sets of source rules need not be symmetrical if the differences reflect different objectives. We conclude that there is a need to reevaluate the current scope of U.S. taxation at source. In the absence of a treaty, the objective of the U.S. source taxation regime should be parity in taxation of U.S.-owned and foreign-owned businesses carried on in the U.S. marketplace and a desired level of taxation on income earned by foreign owned capital employed in the U.S. marketplace. The structure of U.S. rules for taxing international income should not expose the U.S. tax base (all income of U.S. residents and U.S. income, appropriately defined, of nonresidents) to erosion. Relief from source taxation should be extended by treaty, not unilaterally, so that the United States can receive reciprocal benefits and can obtain the treaty partner's assistance to assure that the relief does not go to inappropriate persons. We also urge a comprehensive reexamination of U.S. source rules to take account of the purpose for each rule

Magical realism in a shinagawa Monkey short story by Haruki Murakami: the concept of characteristics of magical realism by Wendy B.Faris

viii, 38 hlm.; ilus.; 25 cm