The original temporal clustering analysis (OTCA) is an effective technique for obtaining brain activation maps when the timing and location of the activation are completely unknown, but its deficiency of sensitivity i...The original temporal clustering analysis (OTCA) is an effective technique for obtaining brain activation maps when the timing and location of the activation are completely unknown, but its deficiency of sensitivity is exposed in processing brain activation signal which is relatively weak. The time slice analysis method based on OTCA is proposed considering the weakness of the functional magnetic resonance imaging (fMRI) signal of the rat model. By dividing the stimulation period into several time slices and analyzing each slice to detect the activated pixels respectively after the background removal, the sensitivity is significantly improved. The inhibitory response in the hypothalamus after glucose loading is detected successfully with this method in the experiment on rat. Combined with the OTCA method, the time slice analysis method based on OTCA is effective on detecting when, where and which type of response will happen after stimulation, even if the fMRI signal is weak.展开更多
Position-spoofing-based attacks seriously threaten the security of Vehicular Ad Hoc Network(VANET).An effective solution to detect position spoofing is location verification.However,since vehicles move fast and the to...Position-spoofing-based attacks seriously threaten the security of Vehicular Ad Hoc Network(VANET).An effective solution to detect position spoofing is location verification.However,since vehicles move fast and the topology changes quickly in VANET,the static location verification method in Wireless Sensor Network(WSN) is not suitable for VANET.Taking into account the dynamic changing topology of VANET and collusion,we propose a Time-Slice-based Location Verification scheme,named TSLV,to resist position spoofing in VANET.Specifically,TSLV transforms the dynamic topology into static topology by time slice and each time slice corresponds to a verification process.The verifier can implement location verification for the corresponding prover.During the verification process,the verifier first filters out vehicles which provide unreasonably claimed locations,and then uses the Mean Square Error(MSE)-based cluster approach to separate the consistent vehicles by time slice,and uses the consistent set for its verification.In addition,security analysis and simulation show that TSLV can defend against the collusion attack effectively.展开更多
In this study, the sliced functional time series (SFTS) model is applied to the Global, Northern and Southern temperature anomalies. We obtained the combined land-surface air and sea-surface water temperature from God...In this study, the sliced functional time series (SFTS) model is applied to the Global, Northern and Southern temperature anomalies. We obtained the combined land-surface air and sea-surface water temperature from Goddard Institute for Space Studies (GISS), NASA. The data are available for Global mean, Northern Hemisphere mean and Southern Hemisphere means (monthly, quarterly and annual) since 1880 to present (updated through March 2019). We analyze the global surface temperature change, compare alternative analyses, and address the questions about the reality of global warming. We detected the outliers during the last century not only in global temperature series but also in northern and southern hemisphere series. The forecasts for the next twenty years are obtained using SFTS models. These forecasts are compared with ARIMA, Random Walk with drift and Exponential Smoothing State Space (ETS) models. The comparison is made on the basis of root mean square error (RMSE), mean absolute percentage error (MAPE) and the length of prediction intervals.展开更多
A simulation of suspended sediment movement relating to tidal and wave forcing during a winter monsoon in November 1983 in the Huanghai and East China Seas continental shelf is attempted by using the model describing ...A simulation of suspended sediment movement relating to tidal and wave forcing during a winter monsoon in November 1983 in the Huanghai and East China Seas continental shelf is attempted by using the model describing the cohesive/non-cohesive sediment resus-pension generated by interactions between currents and waves.model simulation showed that sediment concentration was increased by resuspension at shallow depths during the strong storm conditions due to high bottom stress interacted between currents and waves. This result is in general agreement with observations in horizontal distribution of suspended sediment distribution. At three current meter mooring positions off the southern Shandong Peninsula resuspension occurred only at a depth of 22 m,nearest coastal position and at deeper parts at depths of 51 and 80 m wave-current interaction effects were not significant. It has shown that the present model simulation demonstrated the capability of reproduction of suspended sediment movement under wintertime extreme event reasonably well.展开更多
在低空智联网中,无人机作为空中通信基站、数据传输中继节点和移动网络终端的重要组成部分,凭借其卓越的机动性和适应性,广泛应用于扩展网络覆盖和支持多种业务服务。然而,由于低空智联网面临着网络拓扑动态变化、空域资源稀缺以及多样...在低空智联网中,无人机作为空中通信基站、数据传输中继节点和移动网络终端的重要组成部分,凭借其卓越的机动性和适应性,广泛应用于扩展网络覆盖和支持多种业务服务。然而,由于低空智联网面临着网络拓扑动态变化、空域资源稀缺以及多样化业务需求等挑战,实现有限资源的高效编排和管理仍然是一项艰巨任务。为解决这一问题,通过对无人机网络进行端到端切片,构建满足特定需求的逻辑无人机网络架构。首先,设计了一种分群轨迹预测模型,用于确定分群接入节点的位置,为网络切片的资源预留与优化提供支持。基于此,提出了一种双时间尺度的资源管理框架:在大时间尺度上,采用非线性规划方法将切片重配置问题转化为约束优化问题,优化整体切片效益并合理预留资源;在小时间尺度上,通过针对切片内业务需求的资源调度策略,满足具体业务的传输服务质量(quality of service,QoS)需求。仿真结果表明,该方法增强了低空无人机智联网络在动态环境中的适应性与服务质量,为低空智联网复杂场景下的资源管理和业务保障提供了有效支持。展开更多
基金the National Natural Science Foundation of China (30370432)
文摘The original temporal clustering analysis (OTCA) is an effective technique for obtaining brain activation maps when the timing and location of the activation are completely unknown, but its deficiency of sensitivity is exposed in processing brain activation signal which is relatively weak. The time slice analysis method based on OTCA is proposed considering the weakness of the functional magnetic resonance imaging (fMRI) signal of the rat model. By dividing the stimulation period into several time slices and analyzing each slice to detect the activated pixels respectively after the background removal, the sensitivity is significantly improved. The inhibitory response in the hypothalamus after glucose loading is detected successfully with this method in the experiment on rat. Combined with the OTCA method, the time slice analysis method based on OTCA is effective on detecting when, where and which type of response will happen after stimulation, even if the fMRI signal is weak.
基金supported by National Natural Science Foundation of China under Grant No.60972036
文摘Position-spoofing-based attacks seriously threaten the security of Vehicular Ad Hoc Network(VANET).An effective solution to detect position spoofing is location verification.However,since vehicles move fast and the topology changes quickly in VANET,the static location verification method in Wireless Sensor Network(WSN) is not suitable for VANET.Taking into account the dynamic changing topology of VANET and collusion,we propose a Time-Slice-based Location Verification scheme,named TSLV,to resist position spoofing in VANET.Specifically,TSLV transforms the dynamic topology into static topology by time slice and each time slice corresponds to a verification process.The verifier can implement location verification for the corresponding prover.During the verification process,the verifier first filters out vehicles which provide unreasonably claimed locations,and then uses the Mean Square Error(MSE)-based cluster approach to separate the consistent vehicles by time slice,and uses the consistent set for its verification.In addition,security analysis and simulation show that TSLV can defend against the collusion attack effectively.
文摘In this study, the sliced functional time series (SFTS) model is applied to the Global, Northern and Southern temperature anomalies. We obtained the combined land-surface air and sea-surface water temperature from Goddard Institute for Space Studies (GISS), NASA. The data are available for Global mean, Northern Hemisphere mean and Southern Hemisphere means (monthly, quarterly and annual) since 1880 to present (updated through March 2019). We analyze the global surface temperature change, compare alternative analyses, and address the questions about the reality of global warming. We detected the outliers during the last century not only in global temperature series but also in northern and southern hemisphere series. The forecasts for the next twenty years are obtained using SFTS models. These forecasts are compared with ARIMA, Random Walk with drift and Exponential Smoothing State Space (ETS) models. The comparison is made on the basis of root mean square error (RMSE), mean absolute percentage error (MAPE) and the length of prediction intervals.
文摘A simulation of suspended sediment movement relating to tidal and wave forcing during a winter monsoon in November 1983 in the Huanghai and East China Seas continental shelf is attempted by using the model describing the cohesive/non-cohesive sediment resus-pension generated by interactions between currents and waves.model simulation showed that sediment concentration was increased by resuspension at shallow depths during the strong storm conditions due to high bottom stress interacted between currents and waves. This result is in general agreement with observations in horizontal distribution of suspended sediment distribution. At three current meter mooring positions off the southern Shandong Peninsula resuspension occurred only at a depth of 22 m,nearest coastal position and at deeper parts at depths of 51 and 80 m wave-current interaction effects were not significant. It has shown that the present model simulation demonstrated the capability of reproduction of suspended sediment movement under wintertime extreme event reasonably well.
文摘在低空智联网中,无人机作为空中通信基站、数据传输中继节点和移动网络终端的重要组成部分,凭借其卓越的机动性和适应性,广泛应用于扩展网络覆盖和支持多种业务服务。然而,由于低空智联网面临着网络拓扑动态变化、空域资源稀缺以及多样化业务需求等挑战,实现有限资源的高效编排和管理仍然是一项艰巨任务。为解决这一问题,通过对无人机网络进行端到端切片,构建满足特定需求的逻辑无人机网络架构。首先,设计了一种分群轨迹预测模型,用于确定分群接入节点的位置,为网络切片的资源预留与优化提供支持。基于此,提出了一种双时间尺度的资源管理框架:在大时间尺度上,采用非线性规划方法将切片重配置问题转化为约束优化问题,优化整体切片效益并合理预留资源;在小时间尺度上,通过针对切片内业务需求的资源调度策略,满足具体业务的传输服务质量(quality of service,QoS)需求。仿真结果表明,该方法增强了低空无人机智联网络在动态环境中的适应性与服务质量,为低空智联网复杂场景下的资源管理和业务保障提供了有效支持。
