Node Discovery and Replacement Using Mobile Robot

International audienceA critical problem of wireless sensor networks is the network lifetime, due to the device's limited battery lifetime. The nodes are randomly deployed in the field and the system has no previous knowledge of their position. To tackle this problem we use a mobile robot, that discovers the nodes around it and replaces the active nodes, whose energy is drained, by fully charged inactive nodes. In this paper we propose two localized algorithms, that can run on the robot and that decide, which nodes to replace. We simulate our algorithms and our findings show that all nodes that fail are replaced in a short period of time

Extending Wireless Rechargeable Sensor Network Life without Full Knowledge

When extending the life of Wireless Rechargeable Sensor Networks (WRSN), one challenge is charging networks as they grow larger. Overcoming this limitation will render a WRSN more practical and highly adaptable to growth in the real world. Most charging algorithms require a priori full knowledge of sensor nodes’ power levels in order to determine the nodes that require charging. In this work, we present a probabilistic algorithm that extends the life of scalable WRSN without a priori power knowledge and without full network exploration. We develop a probability bound on the power level of the sensor nodes and utilize this bound to make decisions while exploring a WRSN.We verify the algorithm by simulating a wireless power transfer unmanned aerial vehicle, and charging a WRSN to extend its life. Our results show that, without knowledge, our proposed algorithm extends the life of a WRSN on average 90% of what an optimal full knowledge algorithm can achieve. This means that the charging robot does not need to explore the whole network, which enables the scaling of WRSN. We analyze the impact of network parameters on our algorithm and show that it is insensitive to a large range of parameter values

Recharging <i>vs</i>. Replacing Sensor Nodes Using Mobile Robots for Network Maintenance

International audienceWireless sensor networks (WSNs) have been of very high interest for the research community since years, but the quest for deploying a self-sustained network and effectively prolonging its lifetime has not found a satisfactory answer yet. Two main approaches can be identified that target this objective: either "recharging'' or "replacing'' the sensor nodes that are running out of energy. Of particular interest are solutions where mobile robots are used to execute the above mentioned tasks to automatically and autonomously maintain the WSN, thus reducing human intervention.Recently, the progress in wireless power transfer techniques has boosted research activities in the direction of battery recharging, with high expectations for its application to WSNs. Similarly, also sensor replacement techniques have been widely studied as a means to provide service continuity in the network. Objective of this paper is to investigate the limitations and the advantages of these two research directions. Key decision points must be identified for effectively supporting WSN self-maintenance: (i) which sensor nodes have to be recharged/replaced; (ii) in which order the mobile robot is serving (i.e., recharging/replacing) the nodes and by following which path; (iii) how much energy is delivered to a sensor when recharged. The influence that a set of parameters, relative to both the sensors and the mobile robot, on the decisions will be considered. Centralized and distributed solutions are compared in terms of effectiveness in prolonging the network lifetime and in allowing network self-sustainability. The performance evaluation in a variety of scenarios and network settings offers the opportunity to draw conclusions and to discuss the boundaries for one technique being preferable to the other

A review of Energy Hole mitigating techniques in multi-hop many to one communication and its significance in IoT oriented Smart City infrastructure

A huge increase in the percentage of the world's urban population poses resource management, especially energy management challenges in smart cities. In this paper, the growing challenges of energy management in smart cities have been explored and the significance of elimination of energy holes in converge cast communication has been discussed. The impact of mitigation of energy holes on the network lifetime and energy efficiency has been thoroughly covered. The particular focus of this work has been on energy-efficient practices in two major key enablers of smart cities namely, the Internet of Things (IoT) and Wireless Sensor Networks (WSNs). In addition, this paper presents a robust survey of state-of-the-art energy-efficient routing and clustering methods in WSNs. A niche energy efficiency issue in WSNs routing has been identified as energy holes and a detailed survey and evaluation of various techniques that mitigate the formation of energy holes and achieve balanced energy-efficient routing has been covered

Smart Urban Water Networks

This book presents the paper form of the Special Issue (SI) on Smart Urban Water Networks. The number and topics of the papers in the SI confirm the growing interest of operators and researchers for the new paradigm of smart networks, as part of the more general smart city. The SI showed that digital information and communication technology (ICT), with the implementation of smart meters and other digital devices, can significantly improve the modelling and the management of urban water networks, contributing to a radical transformation of the traditional paradigm of water utilities. The paper collection in this SI includes different crucial topics such as the reliability, resilience, and performance of water networks, innovative demand management, and the novel challenge of real-time control and operation, along with their implications for cyber-security. The SI collected fourteen papers that provide a wide perspective of solutions, trends, and challenges in the contest of smart urban water networks. Some solutions have already been implemented in pilot sites (i.e., for water network partitioning, cyber-security, and water demand disaggregation and forecasting), while further investigations are required for other methods, e.g., the data-driven approaches for real time control. In all cases, a new deal between academia, industry, and governments must be embraced to start the new era of smart urban water systems

Water rights and related water supply issues

Presented during the USCID water management conference held on October 13-16, 2004 in Salt Lake City, Utah. The theme of the conference was "Water rights and related water supply issues."Includes bibliographical references.Proceedings sponsored by the U.S. Department of the Interior, Central Utah Project Completion Act Office and the U.S. Committee on Irrigation and Drainage.Consensus building as a primary tool to resolve water supply conflicts -- Administration to Colorado River allocations: the Law of the River and the Colorado River Water Delivery Agreement of 2003 -- Irrigation management in Afghanistan: the tradition of Mirabs -- Institutional reforms in irrigation sector of Pakistan: an approach towards integrated water resource management -- On-line and real-time water right allocation in Utah's Sevier River basin -- Improving equity of water distribution: the challenge for farmer organizations in Sindh, Pakistan -- Impacts from transboundary water rights violations in South Asia -- Impacts of water conservation and Endangered Species Act on large water project planning, Utah Lake Drainage Basin Water Delivery System, Bonneville Unit of the Central Utah Project -- Economic importance and environmental challenges of the Awash River basin to Ethiopia -- Accomplishing the impossible: overcoming obstacles of a combined irrigation project -- Estimating actual evapotranspiration without land use classification -- Improving water management in irrigated agricultue -- Beneficial uses of treated drainage water -- Comparative assessment of risk mitigation options for irrigated agricutlrue -- A multi-variable approach for the command of Canal de Provence Aix Nord Water Supply Subsystem -- Hierarchical Bayesian Analysis and Statistical Learning Theory II: water management application -- Soil moisture data collection and water supply forecasting -- Development and implementation of a farm water conservation program within the Coachella Valley Water District, California -- Concepts of ground water recharge and well augmentation in northeastern Colorado -- Water banking in Colorado: an experiment in trouble? -- Estimating conservable water in the Klamath Irrigation Project -- Socio-economic impacts of land retirement in Westlands Water District -- EPDM rubber lining system chosen to save valuable irrigation water -- A user-centered approach to develop decision support systems for estimating pumping and augmentation needs in Colorado's South Platte basin -- Utah's Tri-County Automation Project -- Using HEC-RAS to model canal systems -- Potential water and energy conservation and improved flexibility for water users in the Oasis area of the Coachella Valley Water District, California

Urbanization of irrigated land and water transfers

Presented at Urbanization of irrigated land and water transfers: a USCID water management conference on May 28-31, 2008 in Scottsdale, Arizona.An ever increasing challenge for rural irrigation districts in the agriculturally rich San Joaquin Valley of California is adjusting to urbanization while maintaining an effective and efficient irrigation water delivery system. The Oakdale Irrigation District (OID) is currently facing this challenge and has developed a Subdivision/Parcel Map Development Policy that attempts to bring balance to that concern. This paper will present OID's Subdivision Policy and discuss the reasoning behind the conditions and requirements within the policy. It is the intent of this paper to provide other irrigation districts, facing similar urbanization pressures, a foundation for development of similar policies in the hopes of preserving and protecting the water delivery systems so vital to our agricultural communities

Urbanization of irrigated land and water transfers

Presented at Urbanization of irrigated land and water transfers: a USCID water management conference on May 28-31, 2008 in Scottsdale, Arizona.Colorado's Statewide Water Supply Initiative (SWSI) shows that the state has only enough water to meet about 70% of its needs by the year 2030, with most of the gap occurring in the front range urban areas of the state. The SWSI report forecasts that a majority of the water needed for cities will transition from agriculture, which currently uses more than 80% of the state's water. Agricultural communities are concerned what such a transition could mean to their viability. The second phase of SWSI investigated such alternatives to the traditional "buy and dry" as interruptible supply agreements, rotational fallowing leases, water banks and cropping changes. The Lower Arkansas Valley Water Conservancy District (LAVWCD), inspired by the Palo Verde Irrigation District in California, set about to see if ditch companies in the lower Arkansas Valley might agree to form a "super ditch" whereby they would cooperatively pool part of their water to gain operational flexibility and make it available for lease to cities. By working together in a rotational fallowing scheme, they conceptualize that they will have greater bargaining power. Perhaps by converting part of their land from growing hay or corn to growing "water" they could actually benefit financially, and keep their agricultural communities viable. Those attempting to transform the concept into reality are finding that "the devil is in the details." This paper is presented as a sociological case study in the making. The authors detail the steps Super Ditch organizers went through to determine if their scheme is feasible, as well as the hoops they are now going through to try to bring it to fruition