The Internet of Things(IoT)has profoundly impacted our lives and has greatly revolutionized our lifestyle.The terminal devices in an IoT data aggregation application sense real-time data for the remote cloud server to...The Internet of Things(IoT)has profoundly impacted our lives and has greatly revolutionized our lifestyle.The terminal devices in an IoT data aggregation application sense real-time data for the remote cloud server to achieve intelligent decisions.However,the high frequency of collecting user data will raise people concerns about personal privacy.In recent years,many privacy-preserving data aggregation schemes have been proposed.Unfortunately,most existing schemes cannot support either arbitrary aggregation functions,or dynamic user group management,or fault tolerance.In this paper,we propose an efficient and privacy-preserving data aggregation scheme.In the scheme,we design a lightweight encryption method to protect the user privacy by using a ring topology and a random location sequence.On this basis,the proposed scheme supports not only arbitrary aggregation functions,but also flexible dynamic user management.Furthermore,the scheme achieves faulttolerant capabilities by utilizing a future data buffering mechanism.Security analysis reveals that the scheme can achieve the desired security properties,and experimental evaluation results show the scheme's efficiency in terms of computational and communication overhead.展开更多
This paper summarizes some useful concepts about the coordination of directional overcurrent protections.The following key topics are described:the analysis of systems in a ring configuration and only one source of sh...This paper summarizes some useful concepts about the coordination of directional overcurrent protections.The following key topics are described:the analysis of systems in a ring configuration and only one source of short-circuit currents;the impossibility of obtaining selectivity for all the possible system configurations with multiple sources;the need for inverse functions in order to obtain selectivity in systems with multiple sources;the coordination with protections for radial loads;the coordination between instantaneous and delayed functions;the considerations to select the pickup values;the influence of contributions from motors to short circuit currents;the transient configurations due to sequential trips at both line ends;the influence of dynamic behavior of overcurrent functions;the influence of stability constraints;other specific considerations for ground functions;some specific considerations for systems with distributed generation.A summary of these points and their effect on the coordination of directional overcurrent protections is not available in the current literature.This novel description should facilitate the inclusion of these key points in research and coordination studies related to these protective functions.展开更多
The report of the 19th National Congress of the Communist Party of China stated that it was necessary to establish and practice the concept that lucid waters and lush mountains are invaluable assets,treat the ecologic...The report of the 19th National Congress of the Communist Party of China stated that it was necessary to establish and practice the concept that lucid waters and lush mountains are invaluable assets,treat the ecological environment as life,and coordinate the management of mountains,rivers,forests,farmlands,lakes and grasslands.In recent years,China has organized a series of pilot projects for the ecological protection and restoration of mountains,rivers,forests,farmlands,lakes and grasslands,breaking the boundary between administrative divisions,departmental management and ecological elements,and implementing conservation and restoration oriented towards the improvement of ecosystem services,so as to solve the problem of the lack of overall planning for ecological protection and restoration projects and the separated management of ecological elements.This study systematically elaborated the theoretical basis and connotation characteristics of ecological protection and restoration of mountains,rivers,forests,farmlands,lakes and grasslands.It proposed the implementation path of ecological protection and restoration project of mountains,rivers,forests,farmlands,lakes and grasslands by taking the water source conservation area of Beijing-Tianjin-Hebei as a case,so as to provide reference for the implementation and decision-making management of ecological protection and restoration projects in various regions.展开更多
基金supported by the Natural Science Foundation of Fujian Province(2018J01782)the National Natural Science Foundation of China(U1905211)the Educational scientific research project of Fujian Provincial Department of Education(JAT210291)。
文摘The Internet of Things(IoT)has profoundly impacted our lives and has greatly revolutionized our lifestyle.The terminal devices in an IoT data aggregation application sense real-time data for the remote cloud server to achieve intelligent decisions.However,the high frequency of collecting user data will raise people concerns about personal privacy.In recent years,many privacy-preserving data aggregation schemes have been proposed.Unfortunately,most existing schemes cannot support either arbitrary aggregation functions,or dynamic user group management,or fault tolerance.In this paper,we propose an efficient and privacy-preserving data aggregation scheme.In the scheme,we design a lightweight encryption method to protect the user privacy by using a ring topology and a random location sequence.On this basis,the proposed scheme supports not only arbitrary aggregation functions,but also flexible dynamic user management.Furthermore,the scheme achieves faulttolerant capabilities by utilizing a future data buffering mechanism.Security analysis reveals that the scheme can achieve the desired security properties,and experimental evaluation results show the scheme's efficiency in terms of computational and communication overhead.
文摘This paper summarizes some useful concepts about the coordination of directional overcurrent protections.The following key topics are described:the analysis of systems in a ring configuration and only one source of short-circuit currents;the impossibility of obtaining selectivity for all the possible system configurations with multiple sources;the need for inverse functions in order to obtain selectivity in systems with multiple sources;the coordination with protections for radial loads;the coordination between instantaneous and delayed functions;the considerations to select the pickup values;the influence of contributions from motors to short circuit currents;the transient configurations due to sequential trips at both line ends;the influence of dynamic behavior of overcurrent functions;the influence of stability constraints;other specific considerations for ground functions;some specific considerations for systems with distributed generation.A summary of these points and their effect on the coordination of directional overcurrent protections is not available in the current literature.This novel description should facilitate the inclusion of these key points in research and coordination studies related to these protective functions.
文摘The report of the 19th National Congress of the Communist Party of China stated that it was necessary to establish and practice the concept that lucid waters and lush mountains are invaluable assets,treat the ecological environment as life,and coordinate the management of mountains,rivers,forests,farmlands,lakes and grasslands.In recent years,China has organized a series of pilot projects for the ecological protection and restoration of mountains,rivers,forests,farmlands,lakes and grasslands,breaking the boundary between administrative divisions,departmental management and ecological elements,and implementing conservation and restoration oriented towards the improvement of ecosystem services,so as to solve the problem of the lack of overall planning for ecological protection and restoration projects and the separated management of ecological elements.This study systematically elaborated the theoretical basis and connotation characteristics of ecological protection and restoration of mountains,rivers,forests,farmlands,lakes and grasslands.It proposed the implementation path of ecological protection and restoration project of mountains,rivers,forests,farmlands,lakes and grasslands by taking the water source conservation area of Beijing-Tianjin-Hebei as a case,so as to provide reference for the implementation and decision-making management of ecological protection and restoration projects in various regions.
