基于运动相关皮层电位握力运动模式识别研究

面向基于脑-机接口（Brain-computer interface,BCI）的脑-机交互控制（Brain-machine interaction control,BMIC）——直接脑控机器人,提出一种新的左、右手握力运动参数范式,在该范式下探索左、右手握力运动相关皮层电位/运动相关电位（Movement-related potentials,MRPs）的时域特征表示并识别握力运动模式.在涉及左、右手4个不同任务的实验中采集了11个健康被试的脑电信号,任务期间要求被试以2种握力变化模式之一完成自愿握力运动,每种任务随机重复30次.不同握力任务之间具有显著差异的运动相关电位特征用于识别握力运动模式.分别用基于核的Fisher线性判别分析和支持向量机识别4个不同的握力运动任务.研究结果进一步证实运动相关电位可以表征握力运动规划、运动执行和运动监控的脑神经机制过程.基于核的Fisher线性判别分析和支持向量机分别获得24±4%和21±5%的平均错误分类率.最小误分类率是12%,所有被试平均最小误分类率为20.9±5%.与传统的仅仅识别参与运动的肢体类型以及识别单侧肢体运动参数的研究相比,本研究可望为脑-机交互控制/脑控机器人接口提供更多的力控制意图指令,奠定了后续的对比研究基础.     

Efficient synthesis of benzophenone derivatives in Lewis acid ionic liquids

Benzophenone and its derivatives were prepared via Friedel–Crafts acylation reactions using ionic liquids (ILs) of BmimCl–FeCl₃, BmimCl–AlCl₃ and BmimCl–ZnCl₂ as dual catalyst–solvent. Among them, BmimCl–FeCl₃ showed much higher catalytic activity than that observed for the other two ILs, and in conventional organic solvents. In these reaction systems, good to excellent yields (up to 97%) of acylation products were obtained in a short reaction time. This method features high yield, a simple product isolation procedure, ILs reusability and reduced waste discharge, thus rendering this catalytic system both efficient and environmentally friendly.     

不同横断面泄流槽的地震堰塞湖溃决实验研究

堰塞湖的溃决问题是研究堰塞湖的核心内容之一,也是堰塞湖进行排险和处置的重要依据.本文以唐家山堰塞湖为原型,设计室内1∶250的近似模型实验,完成了堰塞湖自然溃决实验、梯形槽堰塞湖溃决实验、三角形槽堰塞湖溃决实验和复式槽堰塞湖溃决实验,通过对溃决过程中堰塞坝内部土体体积含水量变化特征、泄流槽侵蚀特征和溃决流量过程的分析,获得以下认识:(1)溃决初期以下切侵蚀为主、后期以侧蚀为主;溯源侵蚀方面,自然溃决表现最强烈,人工辅助溃决实验中溯源侵蚀由强到弱依次为:复式槽、三角形槽、梯形槽;(2)人工辅助溃决在一定程度上削减了洪峰流量,与自然溃决相比减小了7.7％ ～20.1％,表明开挖人工泄流槽降低坝前水位的措施对于降低堰塞湖溃决风险是可行的;(3)以溃决流量增长率高或到达溃决洪峰时间短为判定溃决初期排泄效率高的标准,对比3组人工槽溃决实验,排泄效率由高到低依次为:三角型横断面、复式横断面、梯形横断面.针对唐家山堰塞湖处置,可在梯形槽基础上开挖三角形槽变为复式槽来进一步提升溃决初期排泄效率.     

Using QuickBird imagery and a production efficiency model to improve crop yield estimation in the semi-arid hilly Loess Plateau,China

Crop yield is a key element in rural development and an indicator of national food security. A method that could estimate crop yield over large hilly areas would be highly desirable. Methods including high spatial resolution satellite imagery have the potential to achieve this objective. This paper describes a method of integrating QuickBird imagery with a production efficiency model (PEM) to estimate crop yield in Zhonglianchuan, a hilly area on Loess Plateau, China. In the PEM model, crop yield is a function of the photosynthetic active radiation (PAR), fraction of absorbed photosynthetically active radiation (f_APAR) and light-use efficiency (LUE). Based on the high spatial resolution QuickBird imagery, a land cover classification is used to attribute a class-specific LUE. The f_APAR is related to spectral vegetation indices (SVI), which can be derived from the satellite images. The LUE, f_APAR and incident PAR data were combined to estimate the crop yield. Farmer-reported crop yield data in 80 representative plots were used to validate the model output. The results indicated QuickBird imagery can improve the accuracy of predicted results relative to the Landsat TM image. The predicted yield approximated well with the data reported by the farmers (r² = 0.86; n = 80). The spatial distributions of crop yield derived here also offers valuable information to manage agricultural production and understand ecosystem functioning.     

A multi-agent system model of a diesel engine using rule induction

The proliferation of a multi-agent system (MAS) and ideas from Artificial Intelligence (AI)/distributed AI have changed the way systems, in general are controlled, and operation of a system (diesel engine) in particular is automated. In this paper a distributed multi-agent architecture for a diesel engine and the knowledge sources that handle electricity generation is developed. Electronic devices and components used for data handling are described. The sensed data are presented in fuzzy logic and calculated in entropy values and depicted in a decision hierarchy. A comparative performance assessment of the proposed multi-agent based system with an existing system is presented and discussed.     

基于横向局部性的多核计算模型

片内多核已成为延长摩尔定律的方式,并行算法设计、编程模型、编译器和运行时系统都需要利用计算模型进行分析。现有多核模型对线程间共享缓存等资源的竞争已有较精确的模型,但是对于线程间数据共享考虑较少。提出线程间共享缓存的横向局部性和任务共享率概念,基于此扩展串行存储层次模型RAM(h),提出考虑任务共享率的多核并行计算模型MRAM(h)。     

面向数字城市规划的城市规划模型研究

作为面向数字城市规划的关键技术,地理信息系统技术、遥感技术支撑下的城市规划模型的研究已经成为城市规划领域的热点问题之一。根据规划模型研究的对象和目的的不同,提出将城市规划模型分为综合规划模型和工程专项规划模型,按照这种分类方式这两种模型的研究进展进行了简要的介绍,并对其研究趋势与研究对策进行了分析。     

基于神经网络和数据融合的红树林群落分类研究

及时准确地掌握红树林群落现状信息可为保护和修复红树林生态系统提供重要的决策依据。对红树林群落进行遥感分类在实际应用中具有较大的意义。但红树林各群落间的光谱差异很微弱,有必要采用多源遥感数据融合的方法来提高分类的精度。本文以珠海淇澳岛红树林区为例,使用SAR图像与TM图像,探讨了监督分类、非监督分类以及神经网络分类3种分类方法和IHS融合、小波融合以及主成分融合3种融合方法对红树林群落进行分类的效果。结果表明,对SAR与TM主成分融合图像应用神经网络分类方法能够取得最好的分类效果。     

Improvement of n-type OTFT electrical stability by gold electrode modification

N-type organic thin film transistors (OTFT) containing modified gold electrodes have been fabricated to investigate the influence of the self assembled monolayer on the transistor characteristics. We report on the effect of drain/source modification by thiol derivatives on the performances, electrical parameters uniformity and electrical stability of C₆₀ transistors. In the literature, electrical instability is often attributed to organic semiconductor (OSC), OSC-insulator interface and insulator. We found here that OSC-metal interfaces affect dramatically the operational stability for bottom gate/bottom contact structure. These effects have been attributed to morphological evolution at the interface metal-OSC induced by the self-assembled monolayers.     

Prediction of ultra-high ON/OFF ratio nanoelectromechanical switching from covalently-bound C60 chains

Applying a first-principles computational approach, we have systematically analyzed the effects of [2+2] cycloaddition oligomerization of fullerene C₆₀ chains on their junction electronic and charge transport properties. For hypothetical infinite C₆₀ chains, we first establish that the polymerization can in principle increase conductance by several orders of magnitude due to the strong orbital hybridizations and band formation. On the other hand, our simulations of the constant-height scanning tunneling microscope (STM) configuration shows that, in agreement with the recent experimental conclusion, the junction electronic structure and device characteristics are virtually unaffected by the C₆₀ chain oligomerization. We further predict that the switching characteristics including even the ON/OFF-state assignment will sensitively depend on the substrate metal species due to the Fermi-level pinning at the substrate-side contact and the subsequent energy level bending toward the STM tip-side contact. We finally demonstrate that a force-feedbacked nanoelectromechanical approach in which both of the C₆₀–electrode distances are kept at short distances before and after switching operations can achieve a metal-independent and significantly improved switching performance due to the Fermi-level pinning in both contacts and the large intrinsic conductance switching capacity of the C₆₀ chain oligomerization.