Regularizing common spatial patterns to improve BCI designs: unified theory and new algorithms

One of the most popular feature extraction algorithms for brain-computer interfaces (BCI) is common spatial patterns (CSPs). Despite its known efficiency and widespread use, CSP is also known to be very sensitive to noise and prone to overfitting. To address this issue, it has been recently proposed to regularize CSP. In this paper, we present a simple and unifying theoretical framework to design such a regularized CSP (RCSP). We then present a review of existing RCSP algorithms and describe how to cast them in this framework. We also propose four new RCSP algorithms. Finally, we compare the performances of 11 different RCSP (including the four new ones and the original CSP), on electroencephalography data from 17 subjects, from BCI competition datasets. Results showed that the best RCSP methods can outperform CSP by nearly 10% in median classification accuracy and lead to more neurophysiologically relevant spatial filters. They also enable us to perform efficient subject-to-subject transfer. Overall, the best RCSP algorithms were CSP with Tikhonov regularization and weighted Tikhonov regularization, both proposed in this paper.     

C波段大栅宽GaAs MESFET的研制

采用高质量的 MBE材料 ,成功地制作了单胞栅宽 2 0 mm的芯片。用栅与 n+凹槽自对准和辅助侧墙工艺制作了栅长 0 .45 μm的 Ti Pt Au栅 ,欧姆接触采用 Au Ge Ni合金工艺 ,采用 PECVD Si N钝化 ,空气桥结构及芯片减薄 Via-Hole工艺。经内匹配得到了单胞芯片 3.7～ 4.2 GHz下 Po≥ 7.3W,Gp≥ 8d B,ηadd>2 5 % ;4胞合成器件 Po≥ 2 5 W,Gp>7d B,ηadd>2 5 %的良好结果。     

Improvement of the MEMS bionic vector hydrophone

A kind of MEMS vector hydrophone with bionics structure was introduced in 2007. As the acoustic-electric transducer structure and the acoustic package of hydrophone have been optimized, the performance of the hydrophone has been greatly improved compared with the previous. This hydrophone calibration was completed in the National Defense Underwater Acoustics Calibration Laboratory of China. According to the test results, the sensitivity of the hydrophone is −165 dB (including pre-amplification 20 dB), the frequency response ranges from 20 Hz to 2 kHz (±5 dB), and this hydrophone has a good directional pattern in the form of “8”-shape.     

Full 3D Printing of Stretchable Piezoresistive Sensor with Hierarchical Porosity and Multimodulus Architecture

A soft piezoresistive sensor with its unique characteristics, such as human skin, light weight, and multiple functions, yields a variety of possible practical applications to skin‐attachable electronics, human–machine interfaces, and electronic skins. However, conventional filler‐matrix piezoresistive sensors often suffer from unsatisfactory sensitivity or insufficient measurement range, as well as significant cross‐correlation between out‐of‐plane pressure and in‐plane extension. Here, a stretchable piezoresistive sensor (SPS) is realized by combining a hierarchically porous sensing element with a multimodulus device architecture via a full 3D printing process. As a result, the sensor exhibits high sensitivity (5.54 kPa^?1), large measurement range (from 10 Pa to 800 kPa), limited cross‐correlation, and excellent durability. Meanwhile, benefiting from the porous structure and mechanical mismatch design, which efficiently distributes the stress away from the sensing element, the device experiences only 7% resistance change at 50% stretching. This approach is employed to rapidly program and readily manufacture stylish, all‐in‐one, functional devices for various applications, demonstrating that the technique is promising for customized stretchable electronics.     

规避风险,SP可持续发展

信息产业部推动SP代码“四网合一”，中国移动要求短信定制业务“二次确认”，“七月新政”正强烈震荡着整个SP行业：SP这棵促使中国电信市场发展的独苗，是否能健康、安全地度过难关取决于他们自身的免疫力和外界的环境是否提供了他们生存的空间。一些行业专家和SP代表指出，鱼龙混杂的SP暴利发展时代已经过去，中国的SP要想自救，必须懂得如何转型，如何规避政策、产业技术、投资等诸多风险。     

传输腔稳频的397nm半导体激光器

商用的半导体激光器由于其长期漂移大,不能满足单离子光频标中离子的激光冷却和长时间探测的目的。因此,采用了传输腔稳频技术减小商用397nm半导体激光器的长期漂移。利用经过Pound-Drever-Hall(PDH)技术锁定的729nm超稳激光器作参考激光,采用扫描的法布里-珀罗(F-P)干涉仪作传输介质,实现了397nm半导体激光器的长稳锁定。稳频后397nm激光器在1h内的漂移小于1MHz,100s的Allan方差小于1×10-10。这些指标为下一步利用传输腔技术实现866nm激光的长稳锁定打下了基础,同时为优化单个钙离子的激光冷却和长时间精密测量提供了条件。     

A 77-GHz Phased-Array Transceiver With On-Chip Antennas in Silicon: Transmitter and Local LO-Path Phase Shifting

Integration of mm-wave multiple-antenna systems on silicon-based processes enables complex, low-cost systems for high-frequency communication and sensing applications. In this paper, the transmitter and LO-path phase-shifting sections of the first fully integrated 77-GHz phased-array transceiver are presented. The SiGe transceiver utilizes a local LO-path phase-shifting architecture to achieve beam steering and includes four transmit and receive elements, along with the LO frequency generation and distribution circuitry. The local LO-path phase-shifting scheme enables a robust distribution network that scales well with increasing frequency and/or number of elements while providing high-resolution phase shifts. Each element of the heterodyne transmitter generates +12.5 dBm of output power at 77 GHz with a bandwidth of 2.5 GHz leading to a 4-element effective isotropic radiated power (EIRP) of 24.5 dBm. Each on-chip PA has a maximum saturated power of +17.5 dBm at 77 GHz. The phased-array performance is measured using an internal test option and achieves 12-dB peak-to-null ratio with two transmit and receive elements active     

Destination-aware metric based social routing for mobile opportunistic networks

Wireless Networks - Although centrality is widely used to differentiate the importance of nodes for social-aware routing in mobile opportunistic networks (MONs), it is destination-agnostic since...     

Further results on local stability of REM algorithm with time-varying delays

This letter presents some further results on the local stability in equilibrium for Internet congestion control algorithm proposed by Low et al., (IEEE/ACM Transactions on Networking, 1999). The propagation delay d(t) is assumed to be time-varying and have maximum and minimum delay bounds (i.e., d/sub m//spl les/d(t)/spl les/d/sub M/), which is more general than the assumption (0相似文献