Traditional wireless sensor networks(WSNs)are typically deployed in remote and hostile environments for information collection.The wireless communication methods adopted by sensor nodes may make the network highly vul...Traditional wireless sensor networks(WSNs)are typically deployed in remote and hostile environments for information collection.The wireless communication methods adopted by sensor nodes may make the network highly vulnerable to various attacks.Traditional encryption and authentication mechanisms cannot prevent attacks launched by internal malicious nodes.The trust-based security mechanism is usually adopted to solve this problem in WSNs.However,the behavioral evidence used for trust estimation presents some uncertainties due to the open wireless medium and the inexpensive sensor nodes.Moreover,how to efficiently collect behavioral evidences are rarely discussed.To address these issues,in this paper,we present a trust management mechanism based on fuzzy logic and a cloud model.First,a type-II fuzzy logic system is used to preprocess the behavioral evidences and alleviate uncertainty.Then,the cloud model is introduced to estimate the trust values for sensor nodes.Finally,a dynamic behavior monitoring protocol is proposed to provide a balance between energy conservation and safety assurance.Simulation results demonstrate that our trust management mechanism can effectively protect the network from internal malicious attacks while enhancing the energy efficiency of behavior monitoring.展开更多
The applicability of ultrasonic pulse velocity （UPV） method to in-situ monitor setting and hardening process of foamed concrete （FC） was systematically investigated. The UPVs of various FC pastes were automaticall...The applicability of ultrasonic pulse velocity （UPV） method to in-situ monitor setting and hardening process of foamed concrete （FC） was systematically investigated. The UPVs of various FC pastes were automatically and continuously measured by a specially designed ultrasonic monitoring apparatus （UMA）. Ultrasonic tests were performed on FC mixtures with different density （300, 500, 800 and 1 000 kg/m3）, and different fly ash contents （0%, 20%, 40% and 60%）. The influence of curing temperatures （20, 40, 60 and 80~C） was also studied. The experimental results show that three characteristic stages can be clearly identified during the setting process of an arbitrary FC paste： dormant stage, acceleration stage, and deceleration stage. Wet density, fly ash content, and curing temperature have great impact on setting behavior. A stepwise increase of the wet density results in shorter dormant stage and larger final UPV. Hydration reaction rate is obviously promoted with an increase in curing temperature. However, the addition fly ash retards the microstn,lcture formation. To aid in comparing with the ultrasonic results, the consistence spread test and Vicat needle test （VNT） were also conducted. A correlation between ultrasonic and VNT results was also established to evaluate the initial and final setting time of the FC mixtures. Finally, certain ranges of UPV with reasonable widths were suggested for the initial and final setting time, respectively.展开更多
Trail use by pedestrians has become more popular in the United States over the last decade although few studies explore the use of technology to monitor high use trails. Monitoring trail users is an important part of ...Trail use by pedestrians has become more popular in the United States over the last decade although few studies explore the use of technology to monitor high use trails. Monitoring trail users is an important part of trail management and an optimal monitoring system usually depends on site-specific characteristics. The objective of this study was to demonstrate how using a multi-methods system to monitor backcountry trail usage in complex spatial settings can be a useful approach for collecting the information that trail managers need. Given the national growth in recreational hiking, we were particularly interested in exploring these issues for highly visited trails close to urban areas and selected a portion of the Larch Trail leading to the top of Multnomah Falls for the study. The multi-methods approach that we used included a combination of automated infrared sensor counts, manual counts, parking lot data from an inductive loop, and travel time estimates collected with low-energy Bluetooth sensors. We found that using multiple methods allowed for a cost-effective and rich data set that considered the site characteristics and the specific need of the trail managers. We expect that many backcountry trail settings have complex landscape and physical design without robust pre-existing baseline data and hope that our insights will aid trail managers as they strive for a sustainable balance between human use and landscape impact.展开更多
While remote trust attestation is a useful concept to detect unauthorized changes to software, the current mechanism only ensures authenticity at the start of the operating system and cannot ensure the action of runni...While remote trust attestation is a useful concept to detect unauthorized changes to software, the current mechanism only ensures authenticity at the start of the operating system and cannot ensure the action of running software. Our approach is to use a behavior-based monitoring agent to make remote attestation more flexible, dynamic, and trustworthy. This approach was mostly made possible by extensive use of process information which is readily available in Unix. We also made use of a behavior tree to effectively record predictable behaviors of each process. In this paper, we primarily focus on building a prototype implementation of such framework, presenting one example built on it, successfully find potential security risks in the run time of a ftp program and then evaluate the performance of this model.展开更多
Behavior choice, coal mine monitoring, and control intensity are combined in a general mathematical model established from the perspective of a behavioral game. A case study is provided with effective conditions of mo...Behavior choice, coal mine monitoring, and control intensity are combined in a general mathematical model established from the perspective of a behavioral game. A case study is provided with effective conditions of monitoring provided. This paper defines the expected value difference of control return and behavior cost difference and discusses the measurement and optimization of variable indexes, including the monitoring intensity and costs of control. The results imply that the control of unsafe behavior can be more effective when monitoring and control of coal mines are both improved. Monitoring will be useful when the rewards for displaying safe behavior, and the monitoring of unsafe behavior, are improved to a high level.展开更多
基金supported in part by the Chongqing Electronics Engineering Technology Research Center for Interactive Learningin part by the Chongqing key discipline of electronic informationin part by the Science and Technology Research Program of Chongqing Municipal Education Commission(KJQN202201630)。
文摘Traditional wireless sensor networks(WSNs)are typically deployed in remote and hostile environments for information collection.The wireless communication methods adopted by sensor nodes may make the network highly vulnerable to various attacks.Traditional encryption and authentication mechanisms cannot prevent attacks launched by internal malicious nodes.The trust-based security mechanism is usually adopted to solve this problem in WSNs.However,the behavioral evidence used for trust estimation presents some uncertainties due to the open wireless medium and the inexpensive sensor nodes.Moreover,how to efficiently collect behavioral evidences are rarely discussed.To address these issues,in this paper,we present a trust management mechanism based on fuzzy logic and a cloud model.First,a type-II fuzzy logic system is used to preprocess the behavioral evidences and alleviate uncertainty.Then,the cloud model is introduced to estimate the trust values for sensor nodes.Finally,a dynamic behavior monitoring protocol is proposed to provide a balance between energy conservation and safety assurance.Simulation results demonstrate that our trust management mechanism can effectively protect the network from internal malicious attacks while enhancing the energy efficiency of behavior monitoring.
基金Founded by the key laboratory of high performance civil engineering materials(2010CEM002)the National Natural Science Foundation of China(51178106,51138002)+1 种基金the Program for New Century Excellent Talents in University(NCET-08-0116),973 Program(2009CB623200)the Program sponsored for scientific innovation research of college graduate in Jiangsu province(CXLX_0105)
文摘The applicability of ultrasonic pulse velocity （UPV） method to in-situ monitor setting and hardening process of foamed concrete （FC） was systematically investigated. The UPVs of various FC pastes were automatically and continuously measured by a specially designed ultrasonic monitoring apparatus （UMA）. Ultrasonic tests were performed on FC mixtures with different density （300, 500, 800 and 1 000 kg/m3）, and different fly ash contents （0%, 20%, 40% and 60%）. The influence of curing temperatures （20, 40, 60 and 80~C） was also studied. The experimental results show that three characteristic stages can be clearly identified during the setting process of an arbitrary FC paste： dormant stage, acceleration stage, and deceleration stage. Wet density, fly ash content, and curing temperature have great impact on setting behavior. A stepwise increase of the wet density results in shorter dormant stage and larger final UPV. Hydration reaction rate is obviously promoted with an increase in curing temperature. However, the addition fly ash retards the microstn,lcture formation. To aid in comparing with the ultrasonic results, the consistence spread test and Vicat needle test （VNT） were also conducted. A correlation between ultrasonic and VNT results was also established to evaluate the initial and final setting time of the FC mixtures. Finally, certain ranges of UPV with reasonable widths were suggested for the initial and final setting time, respectively.
文摘Trail use by pedestrians has become more popular in the United States over the last decade although few studies explore the use of technology to monitor high use trails. Monitoring trail users is an important part of trail management and an optimal monitoring system usually depends on site-specific characteristics. The objective of this study was to demonstrate how using a multi-methods system to monitor backcountry trail usage in complex spatial settings can be a useful approach for collecting the information that trail managers need. Given the national growth in recreational hiking, we were particularly interested in exploring these issues for highly visited trails close to urban areas and selected a portion of the Larch Trail leading to the top of Multnomah Falls for the study. The multi-methods approach that we used included a combination of automated infrared sensor counts, manual counts, parking lot data from an inductive loop, and travel time estimates collected with low-energy Bluetooth sensors. We found that using multiple methods allowed for a cost-effective and rich data set that considered the site characteristics and the specific need of the trail managers. We expect that many backcountry trail settings have complex landscape and physical design without robust pre-existing baseline data and hope that our insights will aid trail managers as they strive for a sustainable balance between human use and landscape impact.
基金funded by Tackling Key Problems in Air Pollution Control Funding from Ministry of Science and Technology of the People’s Republic of China(DQGG0305-01)Chinese Academy of Medical Sciences(CAMS)Innovation Fund for Medical Sciences Program(2021-I2M-1-057)。
基金Supported by the National Natural Science Foun-dation of China (90104005 ,60373087 ,60473023)
文摘While remote trust attestation is a useful concept to detect unauthorized changes to software, the current mechanism only ensures authenticity at the start of the operating system and cannot ensure the action of running software. Our approach is to use a behavior-based monitoring agent to make remote attestation more flexible, dynamic, and trustworthy. This approach was mostly made possible by extensive use of process information which is readily available in Unix. We also made use of a behavior tree to effectively record predictable behaviors of each process. In this paper, we primarily focus on building a prototype implementation of such framework, presenting one example built on it, successfully find potential security risks in the run time of a ftp program and then evaluate the performance of this model.
基金Project supports from The Humanistic and Social Scientific Research Planning Program in Ministry of Education of China (No.12YJA630063)The Social Science Foundation of Jiangsu Province of China (No. 10GLB001)the Ph.D. Programs Foundation of Ministry of Education of China (No. 20100095120014) are acknowledged
文摘Behavior choice, coal mine monitoring, and control intensity are combined in a general mathematical model established from the perspective of a behavioral game. A case study is provided with effective conditions of monitoring provided. This paper defines the expected value difference of control return and behavior cost difference and discusses the measurement and optimization of variable indexes, including the monitoring intensity and costs of control. The results imply that the control of unsafe behavior can be more effective when monitoring and control of coal mines are both improved. Monitoring will be useful when the rewards for displaying safe behavior, and the monitoring of unsafe behavior, are improved to a high level.
