In this paper, we present a novel and efficient scheme for detection of P300 component of the event-related potential in the Brain Computer Interface (BCI) speller paradigm that needs significantly less EEG channels a...In this paper, we present a novel and efficient scheme for detection of P300 component of the event-related potential in the Brain Computer Interface (BCI) speller paradigm that needs significantly less EEG channels and uses a minimal subset of effective features. Removing unnecessary channels and reducing the feature dimension resulted in lower cost and shorter time and thus improved the BCI implementation. The idea was to employ a proper method to optimize the number of channels and feature vectors while keeping high accuracy in classification performance. Optimal channel selection was based on both discriminative criteria and forward-backward investigation. Besides, we obtained a minimal subset of effective features by choosing the discriminant coefficients of wavelet decomposition. Our algorithm was tested on dataset II of the BCI competition 2005. We achieved 92% accuracy using a simple LDA classifier, as compared with the second best result in BCI 2005 with an accuracy of 90.5% using SVM for classification which required more computation, and against the highest accuracy of 96.5% in BCI 2005 that used SVM and much more channels requiring excessive calculations. We also applied our proposed scheme on Hoffmann’s dataset to evaluate the effectiveness of channel reduction and achieved acceptable results.展开更多
We present a simulation on the spatial and temporal characteristics of the indoor propagation channel at 120 GHz. The simulation, applied to a dynamic scenario with randomly placed objects and moving people in a room,...We present a simulation on the spatial and temporal characteristics of the indoor propagation channel at 120 GHz. The simulation, applied to a dynamic scenario with randomly placed objects and moving people in a room, is based on a three-dimensional ray-tracing method. Propagation and reflection mechanisms of electromagnetic waves are discussed in the channel model. The received power in a 0.95-m-height plane is obtained. Comparison between walls and ceiling covered with dielectric mirrors and those with three common wall and ceiling materials are presented. The result shows that the holistic received power level with dielectric mirrors is about 10 dB higher than with other materials.展开更多
This paper studies the nonstationary filtering problem of Markov jump system under <span style="white-space:nowrap;"><i>l</i><sub>2</sub> - <i>l</i><sub>...This paper studies the nonstationary filtering problem of Markov jump system under <span style="white-space:nowrap;"><i>l</i><sub>2</sub> - <i>l</i><sub>∞</sub> </span>performance. Due to the difference in propagation channels, signal strength and phase will inevitably change randomly and cause the waste of signals resources. In response to this problem, a channel fading model with multiplicative noise is introduced. And then a nonstationary filter, which receives signals more efficiently is designed. Meanwhile Lyapunov function is constructed for error analysis. Finally, the gain matrix for filtering is obtained by solving the matrix inequality, and the results showed that the nonstationary filter converges to the stable point more quickly than the traditional asynchronous filter, the stability of the designed filter is verified.展开更多
新能源场站的次/超同步振荡给电力系统的安全稳定运行造成威胁,调相机可以在一定程度上抑制次/超同步振荡。为进一步发挥调相机抑制振荡的能力,提出一种基于储能型双馈调相机的多通道附加阻尼控制策略。首先,设计针对特定频段振荡的附...新能源场站的次/超同步振荡给电力系统的安全稳定运行造成威胁,调相机可以在一定程度上抑制次/超同步振荡。为进一步发挥调相机抑制振荡的能力,提出一种基于储能型双馈调相机的多通道附加阻尼控制策略。首先,设计针对特定频段振荡的附加阻尼控制器,公共耦合点(point of common coupling,PCC)的电流信号经过附加阻尼控制器调制后被输出到机侧控制系统,调节调相机的无功输出实现对系统振荡的有效抑制;其次,根据移相环节的相位补偿偏差将控制器划分为多个通道,每个通道针对特定频段进行振荡抑制;然后,使用Prony算法提取功率振荡信号进行阻尼比计算,评估多通道附加阻尼控制器的振荡抑制效果;最后,在单机系统及新能源场站系统中进行仿真,结果表明多通道附加阻尼控制策略能够显著提高储能型双馈调相机对次/超同步振荡的抑制能力。该策略提高了新能源场站的小干扰稳定性,有利于新能源发电的长期可持续发展。展开更多
文摘In this paper, we present a novel and efficient scheme for detection of P300 component of the event-related potential in the Brain Computer Interface (BCI) speller paradigm that needs significantly less EEG channels and uses a minimal subset of effective features. Removing unnecessary channels and reducing the feature dimension resulted in lower cost and shorter time and thus improved the BCI implementation. The idea was to employ a proper method to optimize the number of channels and feature vectors while keeping high accuracy in classification performance. Optimal channel selection was based on both discriminative criteria and forward-backward investigation. Besides, we obtained a minimal subset of effective features by choosing the discriminant coefficients of wavelet decomposition. Our algorithm was tested on dataset II of the BCI competition 2005. We achieved 92% accuracy using a simple LDA classifier, as compared with the second best result in BCI 2005 with an accuracy of 90.5% using SVM for classification which required more computation, and against the highest accuracy of 96.5% in BCI 2005 that used SVM and much more channels requiring excessive calculations. We also applied our proposed scheme on Hoffmann’s dataset to evaluate the effectiveness of channel reduction and achieved acceptable results.
基金Project supported by the National High Technology Research and Development Program of China (Grant No. 2011AA010205)the National Natural Science Foundation of China (Grant Nos. 61131006 and 61021064)+4 种基金the Major National Development Project of Scientific Instrument and Equipment, China (Grant No. 2011YQ150021)the Important National Science and Technology Specific Projects, China (Grant No. 2011ZX02707)the Major Project, China (Grant No. YYYJ-1123-1)the International Collaboration and Innovation Program on High Mobility Materials Engineering of the Chinese Academy of Sciencesthe Shanghai Municipal Commission of Science and Technology, China (Grant No. 10JC1417000)
文摘We present a simulation on the spatial and temporal characteristics of the indoor propagation channel at 120 GHz. The simulation, applied to a dynamic scenario with randomly placed objects and moving people in a room, is based on a three-dimensional ray-tracing method. Propagation and reflection mechanisms of electromagnetic waves are discussed in the channel model. The received power in a 0.95-m-height plane is obtained. Comparison between walls and ceiling covered with dielectric mirrors and those with three common wall and ceiling materials are presented. The result shows that the holistic received power level with dielectric mirrors is about 10 dB higher than with other materials.
文摘This paper studies the nonstationary filtering problem of Markov jump system under <span style="white-space:nowrap;"><i>l</i><sub>2</sub> - <i>l</i><sub>∞</sub> </span>performance. Due to the difference in propagation channels, signal strength and phase will inevitably change randomly and cause the waste of signals resources. In response to this problem, a channel fading model with multiplicative noise is introduced. And then a nonstationary filter, which receives signals more efficiently is designed. Meanwhile Lyapunov function is constructed for error analysis. Finally, the gain matrix for filtering is obtained by solving the matrix inequality, and the results showed that the nonstationary filter converges to the stable point more quickly than the traditional asynchronous filter, the stability of the designed filter is verified.
文摘新能源场站的次/超同步振荡给电力系统的安全稳定运行造成威胁,调相机可以在一定程度上抑制次/超同步振荡。为进一步发挥调相机抑制振荡的能力,提出一种基于储能型双馈调相机的多通道附加阻尼控制策略。首先,设计针对特定频段振荡的附加阻尼控制器,公共耦合点(point of common coupling,PCC)的电流信号经过附加阻尼控制器调制后被输出到机侧控制系统,调节调相机的无功输出实现对系统振荡的有效抑制;其次,根据移相环节的相位补偿偏差将控制器划分为多个通道,每个通道针对特定频段进行振荡抑制;然后,使用Prony算法提取功率振荡信号进行阻尼比计算,评估多通道附加阻尼控制器的振荡抑制效果;最后,在单机系统及新能源场站系统中进行仿真,结果表明多通道附加阻尼控制策略能够显著提高储能型双馈调相机对次/超同步振荡的抑制能力。该策略提高了新能源场站的小干扰稳定性,有利于新能源发电的长期可持续发展。
