We present SeNeTs and EnviSense. SeNeTs is a powerful software environment for test and validation of sensor network applications. It administrates large-scale sensor networks during execution without affecting commun...
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We present SeNeTs and EnviSense. SeNeTs is a powerful software environment for test and validation of sensor network applications. It administrates large-scale sensor networks during execution without affecting communication among sensor nodes. Moreover, SeNeTs allows efficient debugging of sensor network applications with sophisticated update mechanisms. EnviSense is a graphical frontend to easily configure and administrate sensor networks using SeNeTs. Both software systems are independent on the hardware platform and also able to run stand-alone.
Summary form only given. A distributed denial of service (DDoS) attack is an explicit attempt to interrupt an online service by generating a high volume of malicious traffic. These attacks consume all available networ...
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Summary form only given. A distributed denial of service (DDoS) attack is an explicit attempt to interrupt an online service by generating a high volume of malicious traffic. These attacks consume all available network resources, thus rendering legitimate users unable to access the services. Most existing solutions propose to detect and drop attack packets at or near the destination network where the attack packets have already traversed the network and consumed considerable bandwidth. The aggregate traffic at the destination router may consist of hundreds of thousands of flows making it hard for the router to distinguish between legitimate and malicious packets. So, collateral damage is unavoidable. In this paper, we present a source router preferential dropping (SRPD) scheme to detect possible DDoS attacks and defeat them at their sources. SRPD monitors only high-rate outgoing flows at source networks and preferentially drops the packets belonging to these flows when it senses the existence of an attack. A simulation model is constructed and a number of simulation experiments have been conducted to evaluate the performance of the proposed scheme. Simulation results show that SRPD effectively controls DDoS attacks at their sources and reduces collateral damage to a minimum level.
Summary form only given. Recently, the demand for real-time data services has been increasing. Many e-commerce applications and information services are requiring sophisticated real-time data support. A database is a ...
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Summary form only given. Recently, the demand for real-time data services has been increasing. Many e-commerce applications and information services are requiring sophisticated real-time data support. A database is a core component for such real-time applications. Important to the functionality of real-time databases is data replication, which is used to meet critical time requirements. These requirements vary with different workloads; therefore, different methods of replication control are better suited for different workloads. We examine several methods of replication control and present two new methods for distributed real-time database systems. Our methods are more ideally suited for systems with non-static periodic transaction arrival patterns and systems with random transaction arrival patterns.
We study the problem of quantization for distributed parameter estimation in large scale sensor networks. Assuming a maximum likelihood estimator at the fusion center, we show that the Fisher information is maximized ...
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We study the problem of quantization for distributed parameter estimation in large scale sensor networks. Assuming a maximum likelihood estimator at the fusion center, we show that the Fisher information is maximized by a score-function quantizer. This provides a tight bound on best possible MSE for any unbiased estimator. Furthermore, we show that for a general convex metric, the optimal quantizer belongs to the class of score function quantizers. We also discuss a few practical applications of our results in optimizing estimation performance in distributed and temporal estimation problems
In recent years there has been trend away from single sensor/single (SS/SI) indicator boards as the means by which overall understanding of current work-flow is expressed. Rather, computer screen based supervisory con...
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In recent years there has been trend away from single sensor/single (SS/SI) indicator boards as the means by which overall understanding of current work-flow is expressed. Rather, computer screen based supervisory control and data acquisition (SCADA) systems are being modified to meet this need. This paper looks at some of the limitations inherent in existing SCADA systems and proposes simple display modifications that can be made to improve overall situation awareness (SA). An example from a hydro-power control room is described.
Summary form only given. In wireless ad hoc and sensor networks, building efficient and scalable protocols is a very challenging task due to the lack of infrastructure and the high dynamics. Geographic protocols, that...
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Summary form only given. In wireless ad hoc and sensor networks, building efficient and scalable protocols is a very challenging task due to the lack of infrastructure and the high dynamics. Geographic protocols, that take advantage of the location information of nodes, are very valuable in these environments. The state required to be maintained is minimum and the discovery overhead is low, in addition to the fast response to dynamics. In this paper, we present a state-of-the-art overview of geographic protocols providing basic functions such as geographic routing, geocasting, and geographic-based rendezvous mechanisms. We introduce also some of our work on assessing and improving the robustness of geographic protocols to nonideal realistic conditions corresponding to the real-world environments.
The following topics were dealt with: biotechnology applications; microanalytical device; microfluidic device; microdevices for bioagent detection; rehabilitation; MEMS based prosthesis; auditory prosthesis; retinal p...
The following topics were dealt with: biotechnology applications; microanalytical device; microfluidic device; microdevices for bioagent detection; rehabilitation; MEMS based prosthesis; auditory prosthesis; retinal prosthesis; implantable microdevices; drug delivery systems; microsurgery; tissue engineering; tissue constructs; biomimetic substrates; bioreactors; biohybrid microdevice; nanostructured substrate; microrobots and actuators for biomedicine; nanofluidic technology; micro phenomenon; scaling effect; wearable sensor; wireless energy; micropower; micro imaging technique; packaging; biocompatibility; bioMEMS; cell biology; protein analysis; cell-based sensor; protein-substrate interaction; cell adhesion, cellular growth and cell migration.
We consider the problem of estimating vector-valued variables from noisy "relative" measurements. The measurement model can be expressed in terms of a graph, whose nodes correspond to the variables being est...
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We consider the problem of estimating vector-valued variables from noisy "relative" measurements. The measurement model can be expressed in terms of a graph, whose nodes correspond to the variables being estimated and the edges to noisy measurements of the difference between the two variables. We take the value of one particular variable as a reference and consider the optimal estimator for the differences between the remaining variables and the reference. This type of measurement model appears in several sensor network problems, such as sensor localization and time synchronization. Two algorithms are proposed to compute the optimal estimate in a distributed, iterative manner. The first algorithm implements the Jacobi method to iteratively compute the optimal estimate, assuming all communication is perfect. The second algorithm is robust to temporary communication failures, and converges to the optimal estimate when certain mild conditions on the failure rate are satisfied. It also employs an initialization scheme to improve accuracy in spite of the slow convergence of the Jacobi method
sensor networks are a key technology for the 21st century. Our research aims to formulate and implement a new conceptual model for the next generation of networked sensor devices, which encompasses not only intelligen...
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sensor networks are a key technology for the 21st century. Our research aims to formulate and implement a new conceptual model for the next generation of networked sensor devices, which encompasses not only intelligence in local sensor nodes such that the sensors are self validating, but also the additional capability that the sensors could be networked and communicate with one another and share information. The basic idea is to decompose the processing of monitoring and data rectification tasks and decentralize them on a federated sensor network. The proposed framework has been implemented for a chemical process unit. Experiment results demonstrated the feasibility and thus, the potential of the proposed sensor network.
Summary form only given. Topology control of wireless sensor networks (WSNs) is a key design challenge in terms of extending the lifetime of the network. The paper presents a fault tolerant topology control by adding ...
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Summary form only given. Topology control of wireless sensor networks (WSNs) is a key design challenge in terms of extending the lifetime of the network. The paper presents a fault tolerant topology control by adding necessary redundant nodes to the network's simple communication backbone, which results a higher vertex connectivity degree. It provides not only fault tolerance for unreliable node failure, but also support for upper level protocols. The paper also identifies several factors and synchronization methods which may affect the redundant node selection. A simulation study shows the improvement of network lifetime with a desired vertex connectivity degree.
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