Browsing by Subject "Sensor Network"
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Item In situ sensors for monitoring BMP performance and in-stream pollutant loading(2012-12) Dienhart, Alissa CatherineFor this research, a sensor network was used to evaluate pollutant loads and concentrations in the targeted portions of streams and to evaluate the performance of pond/wetland stormwater best management practices (BMPs). The study sites were chosen to examine whether BMPs achieve their intended purpose of improving surface water quality. This data was also collected with intent of examining whether a sensor network could provide more a more efficient and comprehensive means of monitoring surface waters and BMP systems. Violations of water quality standards for turbidity, dissolved oxygen, and chloride (chronic) were periodically observed at both sampling locations. Measured concentrations of pollutants we converted to loading rates to determine flow profile influences on water quality. Dissolved oxygen and chloride violations were generally observed during periods of low flow, while those for turbidity were generally independent of flow. Water quality downstream of BMPs was often (but not always) better than upstream water quality, suggesting that BMPs controlling stormwater inflow are not contributing to the degradation of downstream water quality. Analysis of water quality before and during rain events indicates that chloride and suspended solids are controlled in the pond/wetland systems studied. Evidence for phosphorus removal was also obtained.Item Sleipnir: a versatile extremely low duty-cycle sensor network.(2010-06) Gu, YuWireless Sensor Network (WSN), is a new information paradigm based on the collaboration of a large number of self-organized sensing nodes. With the increasing demand of cyber-physical interaction, wireless sensor networks have emerged as one of key technologies for many promising applications such as assisted living, military surveillance, infrastructure protection and scientific exploration. Sensor networks are acclaimed to be low-cost, low-profile, and easy to deploy. These attractive advantages, however, imply the resources available to individual nodes are severely limited. Although it is highly possible that the constraints on computation and storage disappear along with the fast development of fabrication techniques, the energy constraint is unlikely to fade away quickly. On the other hand, many sensor network based applications require a lifetime that ranges from several months to tens of years. In order to bridge the gap between limited energy supply and long-term operation requirement of applications, we then have to build extremely low duty-cycle sensor networks where during the operation of sensor applications, sensor nodes activate very briefly and stay in a dormant state for a very long period of time. In this dissertation research, we initiate the first systematic research for low-duty-cycle sensor networks, including a generic sensing architecture, a novel data forwarding scheme for intermittently connected networks and an energy synchronized communication middleware for energy-harvesting sensor networks. The goal of this dissertation research is to provide better understanding of how to build practical and efficient extremely low duty-cycle sensor networks and support those long-term applications such as structure monitoring, traffic control and so on. We hope, toward the very end, this dissertation research can assist the transition of sensor network technology from a research concept to a general-purpose technology available for use for a wide variety of research, government and industry purposes.