this paper discusses the power electronics interfaces and controls for a microgrid paradigm with both DC and AC links. the microgrid is an integrated energy delivery system that consists of interconnected distributed ...
详细信息
this paper discusses the power electronics interfaces and controls for a microgrid paradigm with both DC and AC links. the microgrid is an integrated energy delivery system that consists of interconnected distributed energy resources and controllable loads and can operate in parallel with or isolated from the main power grid. the proposed approach provides a general framework to aggregate a wide range of distributed energy resources at several levels with DC, AC and synchronous links. the collection of the aggregated units at each level represents those distributed units themselves to the upper level as a single self-controlled entity (DC or AC, generator or load). As an integrated energy system, the microgrid appears to the utility grid as indistinguishable from other currently legitimate customers. Advanced power electronics interfaces and their controls make it possible to achieve a desirable coordination among distributed resources, DC links, AC links, and the surrounding power system. In the paper, the variety of power electronics interfaces and control schemes are discussed and their performances are evaluated in a typical DC-linked microgrid and a representative AC-linked microgrid respectively.
the article focuses on the development of a practical groupware system that allows each group member to modify a shared file unlike to traditional groupware systems in which updates from different users will conflict....
详细信息
the article focuses on the development of a practical groupware system that allows each group member to modify a shared file unlike to traditional groupware systems in which updates from different users will conflict. the moderated collaborated mechanism maintains multiple copies of the shared object and also maintains one updateable copy of the shared content on each group member's node by introducing additional storage and conflict resolution overhead.
this work aims at improving the quality of the side information in distributed video coding. Based on genetic algorithms, our proposed technique combines several frames, interpolated using previously developed methods...
详细信息
this work aims at improving the quality of the side information in distributed video coding. Based on genetic algorithms, our proposed technique combines several frames, interpolated using previously developed methods, in a fusion-based approach. Simulation results show a significant improvement in the side information quality compared to other interpolation techniques available in the literature, which greatly improves the rate-distortion performance of a distributed video codec, where the gain in PSNR can reach 6 dB.
Security is a fundamental prerequisite for the survivability and reliability of wireless networks. In a network where limited wireless resources have to be shared, selfish nodes can manipulate relevant network paramet...
详细信息
Security is a fundamental prerequisite for the survivability and reliability of wireless networks. In a network where limited wireless resources have to be shared, selfish nodes can manipulate relevant network parameters to gain more access to the resources, and hence obtain a higher performance than their fair share, while the performance of well-behaved nodes will be significantly degraded. this paper considers the environment of an ieee802.11 WLAN, and proposes a solution from the prospective of a principal-agent system. Our solution uses an incentive and a constraint mechanism to encourage the selfish agent to perform normally. Our method does not modify the ieee 802.11 protocol, but requires an additional principal node only. Simulation results show that our method can overcome the influence of selfish nodes improve the network fairness performance while maintaining the throughput performance.
Asymmetric links commonly exist in low power wireless sensor networks. However, it is difficult to discover and exploit them efficiently. In this work, we propose DEAL, a link management scheme to Discover and Exploit...
详细信息
Asymmetric links commonly exist in low power wireless sensor networks. However, it is difficult to discover and exploit them efficiently. In this work, we propose DEAL, a link management scheme to Discover and Exploit Asymmetric Links efficiently in dense wireless sensor networks. Equipped with a novel feedback mechanism, DEAL dynamically adapts its link maintenance mechanism based on the estimated link quality, and manages the (small) neighbor table so as to retain the most useful information. We implement DEAL in TinyOS and evaluate its performance using both TOSSIM and testbed. the simulation results show that more than 80% of asymmetric links can be discovered and maintained with minimum overhead. Using a collection tree application and ETX as the routing metric, the average path ETX can be reduced by up to 20%. Testbed evaluation also shows that DEAL improves the network routing performance by identifying useful asymmetric links.
this demo presents a mobile wireless sensor system for debris flow monitoring. the objective of this system is to realize long-term and effective debris flow surveillance using low cost wireless sensors. In the system...
详细信息
this demo presents a mobile wireless sensor system for debris flow monitoring. the objective of this system is to realize long-term and effective debris flow surveillance using low cost wireless sensors. In the system, a set of robust wireless sensors are designed to deploy on riverbed and cooperatively observe the moving debris flows. Our mobile sensors are intended to be carried along by the debris flow. As the sensors move along, they are able to measure the internal parameters, such as vibration frequency, amplitude, moving direction and velocity, of the debris flow. By utilizing the proposed energy-saving mechanism on the WSN platform, the mobile sensors can continuously operate up to six months with merely two alkaline D cell batteries. the proposed system provides the abilities to collect high-fidelity data for civil engineering applications to analyze and determine the occurrence of debris flows, as well as estimate the damage.
Wireless sensor networks are going to allow for ubiquitous health monitoring, improving users' well-being, the healthcare system, and helping to quickly react on emergency situations. Meeting the strict security n...
详细信息
Wireless sensor networks are going to allow for ubiquitous health monitoring, improving users' well-being, the healthcare system, and helping to quickly react on emergency situations. Meeting the strict security needs of these ubiquitous medical applications is a big challenge, since safety and privacy of medical data has to be guaranteed all the way from the sensor nodes to the back-end services, the system has to fulfill latency needs, and lots of mobility is expected. In this paper, we introduce a deployment model for wireless sensor networks for pervasive healthcare based on the concepts of patient area networks and medical sensor networks, and propose a complete and efficient security framework for them. Our security framework is organized into three layers, addressing the operational requirements and security needs at the patient area network, medical sensor network and back-end levels. We specify how these layers are interconnected with each other as well as the needed security mechanisms that allow for the efficient and practical deployment of secure pervasive healthcare systems based on wireless sensor networks.
Investigation of components and their interaction in operation is especially important for the design of systems using ambient energy. the limited energy harvester's efficiency, the strong fluctuating behaviour of...
详细信息
Investigation of components and their interaction in operation is especially important for the design of systems using ambient energy. the limited energy harvester's efficiency, the strong fluctuating behaviour of the ambient energy sources as well as the limited storage unit's capacities command the actual performance of such systems. In order to design energy autonomous systems an automated test platform has been developed, to characterise energy harvesting systems at component and system level. Different energy harvester and system components have been investigated and their interaction with each other has been evaluated. Using the developed test platform, the efficiency of energy conversion and energy management can be investigated thoroughly.
Recent study reveals that great benefit can be achieved for data gathering in wireless sensor networks by employing mobile collectors that gather the data via short-range communications. To pursue maximum energy savin...
详细信息
ISBN:
(纸本)9781424451142
Recent study reveals that great benefit can be achieved for data gathering in wireless sensor networks by employing mobile collectors that gather the data via short-range communications. To pursue maximum energy saving at sensor nodes, intuitively, a mobile collector should traverse the transmission range of each sensor in the field such that the transmission of each packet can be constrained to a single hop. However, this approach may lead to significantly increased data collection latency due to the low moving velocity of the mobile collector. On the other hand, data collection latency can be effectively shortened by performing local aggregation via multi-hop transmissions and then uploading the packets from relay sensors to the mobile collector. However, local transmission hops should not be arbitrarily increased since it may incur too much energy consumption on packet relays, which would adversely affect the overall efficiency of mobile data collection. Based on these observations, in this paper, we study the tradeoff between energy saving and data collection latency in mobile data gathering by exploring a balance between the relay hop count of local data aggregation and the moving tour length of the mobile collector. We first propose a polling-based mobile collection approach and formulate it into an optimization problem, named bounded relay hop mobile data collection (BRH-MDC). Specifically, a subset of sensors will be selected as polling points that buffer locally aggregated data and upload the data to the mobile collector when it arrives. In the meanwhile, when sensors are affiliated withthese polling points, it is guaranteed that any packet relay is bounded within a given number of hops. We then give two efficient algorithms to select polling points among sensors. the effectiveness of our approach is validated through extensive simulations.
Wireless sensor networks are going to allow for ubiquitous health monitoring, improving users' well-being, making the healthcare system more efficient, and helping to quickly react on emergency situations. Meeting...
详细信息
Wireless sensor networks are going to allow for ubiquitous health monitoring, improving users' well-being, making the healthcare system more efficient, and helping to quickly react on emergency situations. Meeting the strict security needs of ubiquitous medical applications is a big challenge: safety and privacy of patient data has to be guaranteed all the way from the sensor nodes to the back-end services, the system has to fulfill latency needs, and lots of mobility is expected. In this paper, we introduce a deployment model for wireless sensor networks for pervasive healthcare based on the concepts of patient area and medical sensor networks. We propose a complete and efficient security framework organized into three layers, addressing the operational requirements and security needs at the patient area network, medical sensor network, and back-end levels. We specify how these layers are interconnected with each other as well as the needed security and privacy mechanisms that allow for the efficient and practical deployment of secure pervasive healthcare systems based on wireless sensor networks.
暂无评论