针对升空通信平台大规模多输入多输出(Multiple-Input Multiple-Output,MIMO)系统中在通信接入阶段遭受导频攻击引入的信息泄露问题,提出了一种基于空间波束不变性的导频接入攻击检测与消除方法。该方案基于用户空间波束域信道结构特征...针对升空通信平台大规模多输入多输出(Multiple-Input Multiple-Output,MIMO)系统中在通信接入阶段遭受导频攻击引入的信息泄露问题,提出了一种基于空间波束不变性的导频接入攻击检测与消除方法。该方案基于用户空间波束域信道结构特征,在缺少信道先验信息的条件下使用点排序簇结构(Ordering Points to Identify the Clustering Structure,OPTICS)聚类算法,分离提取接入攻击与合法用户的波束域信道,消除接入攻击导致的信号损伤,实现合法用户信号安全传输。仿真结果表明,所提方案能够有效降低导频接入攻击对系统安全传输的影响。展开更多
Objective To investigate the variations of electroencephalogram (EEG) and brain evoked potentials (BEPs) to explore their clinical value in diagnosing Al zheimer's disease (AD) and senile schizophrenia (SS) Meth...Objective To investigate the variations of electroencephalogram (EEG) and brain evoked potentials (BEPs) to explore their clinical value in diagnosing Al zheimer's disease (AD) and senile schizophrenia (SS) Methods Thirtynine patients with AD according to DSMR (Diagnostic and Statistical Manual of Mental Disorders, rev), 34 patients with SS and 40 normal aged subjects were included in this study The BEAMEEG (brain elect rical activity mapping), auditory evoked potentials (AEP), visual evoked potent ials (VEP), auditory brainstem response (ABR) and cognitive P300 were recorded f rom the scalps of all subjects with a Dantec Concerto SEEG16 Instrument Results The abnormal ratio of EEG was significantly higher in AD patients (875%, P<005) than in normal controls (282%) and schizophrenic patien ts (667%) In AD and SS group, a lowdensity band was seen in BEAMEEG Bo th and power at all recording sites were increased significantly in AD gro up than in normal controls (P<005); the and power were increased at major recording sites in SS group In AD group, the power of band was decreased at the posttemporal, anteriortemporal and vertical areas (P<0 05); the same va riation presented at the frontal and vertical areas in SS group (P<005 or P<00 1) The power of band of AD patients was increased at the frontal and post t emporal areas (P<005 or P<001); the same increasing appeared at the frontal, m idtemporal and occipital areas in SS patients (P<005) Significantly pr olonge d latencies were found with the major components of both AEP and VEP of AD patie nts Schizophrenic patients presented reduced P2 latency of VEP The amplitud es of major components of AEP, VEP and P300 were decreased in SS patients, and wer e further decreased in AD patients AD patients presented more abnormal ABR tha n SS patients All the variations of BEPs had statistical significance (P<0 05 or P<001) The abovementioned variations in SS group were compared with t he cor responding data of 46 general schizophrenics (one of our earlier stu展开更多
文摘针对升空通信平台大规模多输入多输出(Multiple-Input Multiple-Output,MIMO)系统中在通信接入阶段遭受导频攻击引入的信息泄露问题,提出了一种基于空间波束不变性的导频接入攻击检测与消除方法。该方案基于用户空间波束域信道结构特征,在缺少信道先验信息的条件下使用点排序簇结构(Ordering Points to Identify the Clustering Structure,OPTICS)聚类算法,分离提取接入攻击与合法用户的波束域信道,消除接入攻击导致的信号损伤,实现合法用户信号安全传输。仿真结果表明,所提方案能够有效降低导频接入攻击对系统安全传输的影响。
文摘Objective To investigate the variations of electroencephalogram (EEG) and brain evoked potentials (BEPs) to explore their clinical value in diagnosing Al zheimer's disease (AD) and senile schizophrenia (SS) Methods Thirtynine patients with AD according to DSMR (Diagnostic and Statistical Manual of Mental Disorders, rev), 34 patients with SS and 40 normal aged subjects were included in this study The BEAMEEG (brain elect rical activity mapping), auditory evoked potentials (AEP), visual evoked potent ials (VEP), auditory brainstem response (ABR) and cognitive P300 were recorded f rom the scalps of all subjects with a Dantec Concerto SEEG16 Instrument Results The abnormal ratio of EEG was significantly higher in AD patients (875%, P<005) than in normal controls (282%) and schizophrenic patien ts (667%) In AD and SS group, a lowdensity band was seen in BEAMEEG Bo th and power at all recording sites were increased significantly in AD gro up than in normal controls (P<005); the and power were increased at major recording sites in SS group In AD group, the power of band was decreased at the posttemporal, anteriortemporal and vertical areas (P<0 05); the same va riation presented at the frontal and vertical areas in SS group (P<005 or P<00 1) The power of band of AD patients was increased at the frontal and post t emporal areas (P<005 or P<001); the same increasing appeared at the frontal, m idtemporal and occipital areas in SS patients (P<005) Significantly pr olonge d latencies were found with the major components of both AEP and VEP of AD patie nts Schizophrenic patients presented reduced P2 latency of VEP The amplitud es of major components of AEP, VEP and P300 were decreased in SS patients, and wer e further decreased in AD patients AD patients presented more abnormal ABR tha n SS patients All the variations of BEPs had statistical significance (P<0 05 or P<001) The abovementioned variations in SS group were compared with t he cor responding data of 46 general schizophrenics (one of our earlier stu
