It, from the perspective of cohesion, extracts three types of topic-shift markers used in this genre, namely 'change of narrators', 'change of objects being talked about', and 'temporal adverbials&...It, from the perspective of cohesion, extracts three types of topic-shift markers used in this genre, namely 'change of narrators', 'change of objects being talked about', and 'temporal adverbials' to analyze four journalistic reports from the network media and draws the conclusion that cohesion between two topic units is usually weaker than that within a specific topic fragment.展开更多
Introduction EQUATOR Network provides unique access to collated expertise and resources for good reporting of health research, The resources are aimed at researchers （authors of research articles）, journal editors, ...Introduction EQUATOR Network provides unique access to collated expertise and resources for good reporting of health research, The resources are aimed at researchers （authors of research articles）, journal editors, peer reviewers, and developers of reporting guidelines,展开更多
In sensor networks,the adversaries can inject false data reports from compromised nodes.Previous approaches to filter false reports,e.g.,SEF,only verify the correctness of the message authentication code (MACs) carrie...In sensor networks,the adversaries can inject false data reports from compromised nodes.Previous approaches to filter false reports,e.g.,SEF,only verify the correctness of the message authentication code (MACs) carried in each data report on intermediate nodes,thus cannot filter out fake reports that are forged in a collaborative manner by a group of compromised nodes,even if these compromised nodes distribute in different geographical areas.Furthermore,if the adversary obtains keys from enough (e.g.,more than t in SEF) distinct key partitions,it then can successfully forge a data report without being detected en-route.A neighbor information based false report filtering scheme (NFFS) in wireless sensor networks was presented.In NFFS,each node distributes its neighbor information to some other nodes after deployment.When a report is generated for an observed event,it must carry the IDs and the MACs from t detecting nodes.Each forwarding node checks not only the correctness of the MACs carried in the report,but also the legitimacy of the relative position of these detecting nodes.Analysis and simulation results demonstrate that NFFS can resist collaborative false data injection attacks efficiently,and thus can tolerate much more compromised nodes than existing schemes.展开更多
Sensor networks include numerous sensor nodes that are vulnerable to physical attacks from the outside because they operate in open environments. The sensor nodes are compromised by an attacker. The compromised nodes ...Sensor networks include numerous sensor nodes that are vulnerable to physical attacks from the outside because they operate in open environments. The sensor nodes are compromised by an attacker. The compromised nodes generate false reports and inject the reports into sensor networks. The false report injection attacks deplete energy of the sensor nodes. Ye et al. proposed Statistical En-Route Filtering (SEF) to defend sensor nodes against the false report injection attacks. In SEF, sensor nodes verify the event reports based on a fixed probability. Thus, the verification energy of a node is the same whether the report is false or valid. But when there are few false reports, energy for verifying legitimate reports may be wasted. In this paper, we propose a method in which each node controls a probability of attempts at verification of an event report to reduce the wasted energy. The probability is determined through consideration of the number of neighboring nodes, the number of hops from the node to the sink node, and the rate of false reports among the 10 most recent event reports forwarded to a node. We simulated our proposed method to prove its energy efficiency. After the simulation, we confirmed that the proposed method is more efficient than SEF for saving sensor node’s energy.展开更多
Continuous-monitoring (CM) of natural phenomenon is one of the major streams of applications in wireless sensor networks (WSNs), where aggregation and clustering techniques are beneficial as correlation dominates in b...Continuous-monitoring (CM) of natural phenomenon is one of the major streams of applications in wireless sensor networks (WSNs), where aggregation and clustering techniques are beneficial as correlation dominates in both spatial and temporal aspects of sensed phenomenon. Conversely, in Event Driven Reporting (EDR), the efficient transmission of sensitive data related to some predefined alarm cases is of major importance. As such, reporting latency is a more important performance parameter. However, in some applications, the transmission of both CM and EDR data is encouraged or even required. For either CM or EDR applications, system performance can be greatly improved when both the number of packets to be transmitted as well as the packet size is reduced. This is especially true for highly dense sensor networks where many nodes detect the same values for the sensed phenomenon. Building on this, this paper focuses on studying and proposing compression techniques to improve the system performance in terms of energy consumption and reporting latency in both CM and EDR applications. Furthermore, we extend our analysis to hybrid networks where CM and EDR are required simultaneously. Specifically, this paper presents a simple aggregation technique named smart aggregation (SAG) for the CM applications and an event driven scheme named compression cluster scheme in spatial correlated region (CC_SCR). The proposed SAG exploits both spatial and temporal correlations where CC_SCR exploits the spatial correlation of such networks by data compression. Rationalizing the developments is attained by simulations that compare energy efficiency of the proposed SAG with k-hop aggregation and CM based event driven reporting (CMEDR) schemes. Results of CC_SCR show that the technique may reduce the energy consumption drastically. In some specific cases the reduction becomes more than 10 times compared to a classical clustering scheme. Two different strategies for the transmission of event reports through the CM infrastructure are incorporated: PER and NPER protocols. Both strategies take advantage of the cluster-based architecture which assigns a TDMA schedule for the CM data transmission while using NP/CSMA for the transmission of the event information. Consequently, no extra energy is consumed for separate event clusters. As such, the number of packets to be transmitted is greatly reduced.展开更多
文摘It, from the perspective of cohesion, extracts three types of topic-shift markers used in this genre, namely 'change of narrators', 'change of objects being talked about', and 'temporal adverbials' to analyze four journalistic reports from the network media and draws the conclusion that cohesion between two topic units is usually weaker than that within a specific topic fragment.
文摘Introduction EQUATOR Network provides unique access to collated expertise and resources for good reporting of health research, The resources are aimed at researchers （authors of research articles）, journal editors, peer reviewers, and developers of reporting guidelines,
基金Projects(61173169,61103203,70921001)supported by the National Natural Science Foundation of ChinaProject(NCET-10-0798)supported by Program for New Century Excellent Talents in University of China
文摘In sensor networks,the adversaries can inject false data reports from compromised nodes.Previous approaches to filter false reports,e.g.,SEF,only verify the correctness of the message authentication code (MACs) carried in each data report on intermediate nodes,thus cannot filter out fake reports that are forged in a collaborative manner by a group of compromised nodes,even if these compromised nodes distribute in different geographical areas.Furthermore,if the adversary obtains keys from enough (e.g.,more than t in SEF) distinct key partitions,it then can successfully forge a data report without being detected en-route.A neighbor information based false report filtering scheme (NFFS) in wireless sensor networks was presented.In NFFS,each node distributes its neighbor information to some other nodes after deployment.When a report is generated for an observed event,it must carry the IDs and the MACs from t detecting nodes.Each forwarding node checks not only the correctness of the MACs carried in the report,but also the legitimacy of the relative position of these detecting nodes.Analysis and simulation results demonstrate that NFFS can resist collaborative false data injection attacks efficiently,and thus can tolerate much more compromised nodes than existing schemes.
文摘Sensor networks include numerous sensor nodes that are vulnerable to physical attacks from the outside because they operate in open environments. The sensor nodes are compromised by an attacker. The compromised nodes generate false reports and inject the reports into sensor networks. The false report injection attacks deplete energy of the sensor nodes. Ye et al. proposed Statistical En-Route Filtering (SEF) to defend sensor nodes against the false report injection attacks. In SEF, sensor nodes verify the event reports based on a fixed probability. Thus, the verification energy of a node is the same whether the report is false or valid. But when there are few false reports, energy for verifying legitimate reports may be wasted. In this paper, we propose a method in which each node controls a probability of attempts at verification of an event report to reduce the wasted energy. The probability is determined through consideration of the number of neighboring nodes, the number of hops from the node to the sink node, and the rate of false reports among the 10 most recent event reports forwarded to a node. We simulated our proposed method to prove its energy efficiency. After the simulation, we confirmed that the proposed method is more efficient than SEF for saving sensor node’s energy.
文摘Continuous-monitoring (CM) of natural phenomenon is one of the major streams of applications in wireless sensor networks (WSNs), where aggregation and clustering techniques are beneficial as correlation dominates in both spatial and temporal aspects of sensed phenomenon. Conversely, in Event Driven Reporting (EDR), the efficient transmission of sensitive data related to some predefined alarm cases is of major importance. As such, reporting latency is a more important performance parameter. However, in some applications, the transmission of both CM and EDR data is encouraged or even required. For either CM or EDR applications, system performance can be greatly improved when both the number of packets to be transmitted as well as the packet size is reduced. This is especially true for highly dense sensor networks where many nodes detect the same values for the sensed phenomenon. Building on this, this paper focuses on studying and proposing compression techniques to improve the system performance in terms of energy consumption and reporting latency in both CM and EDR applications. Furthermore, we extend our analysis to hybrid networks where CM and EDR are required simultaneously. Specifically, this paper presents a simple aggregation technique named smart aggregation (SAG) for the CM applications and an event driven scheme named compression cluster scheme in spatial correlated region (CC_SCR). The proposed SAG exploits both spatial and temporal correlations where CC_SCR exploits the spatial correlation of such networks by data compression. Rationalizing the developments is attained by simulations that compare energy efficiency of the proposed SAG with k-hop aggregation and CM based event driven reporting (CMEDR) schemes. Results of CC_SCR show that the technique may reduce the energy consumption drastically. In some specific cases the reduction becomes more than 10 times compared to a classical clustering scheme. Two different strategies for the transmission of event reports through the CM infrastructure are incorporated: PER and NPER protocols. Both strategies take advantage of the cluster-based architecture which assigns a TDMA schedule for the CM data transmission while using NP/CSMA for the transmission of the event information. Consequently, no extra energy is consumed for separate event clusters. As such, the number of packets to be transmitted is greatly reduced.
