318 research outputs found

    Decentralized and Partially Decentralized Multi-Agent Reinforcement Learning

    Get PDF
    Indiana University-Purdue University Indianapolis (IUPUI)Multi-agent systems consist of multiple agents that interact and coordinate with each other to work towards to certain goal. Multi-agent systems naturally arise in a variety of domains such as robotics, telecommunications, and economics. The dynamic and complex nature of these systems entails the agents to learn the optimal solutions on their own instead of following a pre-programmed strategy. Reinforcement learning provides a framework in which agents learn optimal behavior based on the response obtained from the environment. In this thesis, we propose various novel de- centralized, learning automaton based algorithms which can be employed by a group of interacting learning automata. We propose a completely decentralized version of the estimator algorithm. As compared to the completely centralized versions proposed before, this completely decentralized version proves to be a great improvement in terms of space complexity and convergence speed. The decentralized learning algorithm was applied; for the first time; to the domains of distributed object tracking and distributed watershed management. The results obtained by these experiments show the usefulness of the decentralized estimator algorithms to solve complex optimization problems. Taking inspiration from the completely decentralized learning algorithm, we propose the novel concept of partial decentralization. The partial decentralization bridges the gap between the completely decentralized and completely centralized algorithms and thus forms a comprehensive and continuous spectrum of multi-agent algorithms for the learning automata. To demonstrate the applicability of the partial decentralization, we employ a partially decentralized team of learning automata to control multi-agent Markov chains. More flexibility, expressiveness and flavor can be added to the partially decentralized framework by allowing different decentralized modules to engage in different types of games. We propose the novel framework of heterogeneous games of learning automata which allows the learning automata to engage in disparate games under the same formalism. We propose an algorithm to control the dynamic zero-sum games using heterogeneous games of learning automata

    Effect of Stakeholder Attitudes on the Optimization of Watershed Conservation Practices

    Get PDF
    Indiana University-Purdue University Indianapolis (IUPUI)Land use alterations have been major drivers for modifying hydrologic cycles in many watersheds nationwide. Imbalances in this cycle have led to unexpected or extreme changes in flood and drought patterns and intensities, severe impairment of rivers and streams due to pollutants, and extensive economic losses to affected communities. Eagle Creek Watershed (ECW) is a typical Midwestern agricultural watershed with a growing urban land-use that has been affected by these problems. Structural solutions, such as ditches and tiles, have helped in the past to reduce the flooding problem in the upland agricultural area. But these structures have led to extensive flooding and water quality problems downstream and loss of moisture storage in the soil upstream. It has been suggested that re-naturalization of watershed hydrology via a spatially-distributed implementation of non-structural and structural conservation practices, such as cover crops, wetlands, riparian buffers, grassed waterways, etc. will help to reduce these problems by improving the upland runoff (storing water temporally as moisture in the soil or in depression storages). However, spatial implementation of these upland storage practices poses hurdles not only due to the large number of possible alternatives offered by physical models, but also by the effect of tenure, social attitudes, and behaviors of landowners that could further add complexities on whether and how these practices are adopted and effectively implemented for benefits. This study investigates (a) how landowner tenure and attitudes can be used to identify promising conservation practices in an agricultural watershed, (b) how the different attitudes and preferences of stakeholders can modify the effectiveness of solutions obtained via classic optimization approaches that do not include the influence of social attitudes in a watershed, and (c) how spatial distribution of landowner tenure affects the spatial optimization of conservation practices on a watershed scale. Results showed two main preferred practices, one for an economic evaluation (filter strips) and one for an environmental perspective (wetlands). A land tenure comparison showed differences in spatial distribution of systems considering all the conservation practices. It also was observed that cash renters selected practices will provide a better cost-revenue relation than the selected optimal solution

    Data fusion approach for eucalyptus trees identification

    Get PDF
    UIDB/00066/2020 DSAIPA/AI/0100/2018Remote sensing is based on the extraction of data, acquired by satellites or aircrafts, through multispectral images, that allow their remote analysis and classification. Analysing those images with data fusion techniques is a promising approach for identification and classification of forest types. Fusion techniques can aggregate various sources of heterogeneous information to generate value-added maps, facilitating forest-type classification. This work applies a data fusion algorithm, denoted FIF (Fuzzy Information Fusion), which combines computational intelligence techniques with multicriteria concepts and techniques, to automatically distinguish Eucalyptus trees from satellite images. The algorithm customization was performed with a Portuguese area planted with Eucalyptus. After customizing and validating the approach with several representative scenarios to assess its suitability for automatic classification of Eucalyptus, we tested on a large tile obtaining a sensitivity of 69.61%, with a specificity of 99.43%, and an overall accuracy of 98.19%. This work demonstrates the potential of our approach to automatically classify specific forest types from satellite images, since this is a novel approach dedicated to the identification of eucalyptus trees.publishersversionpublishe

    Water and Development: An Evaluation of World Bank Support, 1997-2007, Volume 1

    Get PDF
    The Independent Evaluation Group at the World Bank has evaluated a decade of the Bank's water lending and grants in terms of overall shifts in the water portfolio and project performance, as well as successes and failures in addressing water resource management, environment, water use and service delivery, and institutions and water. The Bank increased its lending for water during the period and has generally seen improvements in project performance; however, IWRM has made limited progress in client countries, environmental restoration has been underemphasized by the Bank, sanitation needs much greater attention, and support for institutional reform and capacity building has had limited success

    African Water Laws: Plural Legislative Frameworks For Rural Water Management in Africa: an international workshop, Johannesburg, South Africa, 26-28 January 2005

    Get PDF
    Water law / Water management / Water policy / Poverty / River basins / Irrigation systems / Institutions / Wetlands

    Water-Wise Cities and Sustainable Water Systems

    Get PDF
    Building water-wise cities is a pressing need nowadays in both developed and developing countries. This is mainly due to the limitation of the available water resources and aging infrastructure to meet the needs of adapting to social and environmental changes and for urban liveability. This is the first book to provide comprehensive insights into theoretical, systematic, and engineering aspects of water-wise cities with a broad coverage of global issues. The book aims to (1) provide a theoretical framework of water-wise cities and associated sustainable water systems including key concepts and principles, (2) provide a brand-new thinking on the design and management of sustainable urban water systems of various scales towards a paradigm shift under the resource and environmental constraints, and (3) provide a technological perspective with successful case studies of technology selection, integration, and optimization on the “fit-for-purpose” basis

    Restoring the ecological quality of riparian ecosystems - a multi-level approach

    Get PDF
    Doutoramento em Engenharia Florestal e dos Recursos Naturais - Instituto Superior de Agronomia / ULMany European rivers and floodplains have been subjected to long periods of anthropogenic degradation. Activities like land drainage, construction of dams and weirs, channelization, water abstraction and pollution, resulted, among others, in the loss of floodplains and wetlands, high sediment runoff, biodiversity losses, lowering of the river and water table levels and increase in peak flows. Thus, this thesis focuses on a multi-level top to bottom approach to freshwater ecosystem restoration, addressing the legislation restoration drivers, as well as the restoration at the basin and river section levels. The main conclusions are: a) to improve freshwater restoration success in Europe it is highly recommended to create more ecosystem restoration soft law and reinforcement mechanisms related with governance, quality, stakeholders, publicity and research; b) there is a joint effect of climate change and land use on river water quality, meaning that proposed environmental conservation measures may be too conservative to have a significant effect in river nitrogen concentration, particularly in a climate change context; c) local population awareness and participation are as essential for habitat restoration success as grazing herbivores exclusion, river pollutant load, water table levels and tree installation techniques; d) the sampling of a river section to assess the influence of the liquid effluent from an acid bisulfite pulp mill on river water quality did not reveal particularly high levels of pollution directly related to the mill, in spite of relevant levels of total phosphorous and dissolved lignin; and e) cork and Tasmanian blue gum bark are capable of enhancing biological denitrification in laboratory batch tests. The implementation of ecologically effective restoration should be flexible to adjust to changing climate and societal priorities, retaining simultaneously the capacity to integrate information from new technologies into site assessment and restoration planningN/
    corecore