溶剂效应对FOX-7晶体形貌影响的分子动力学模拟研究

利用Materials Studio软件中Growth Morphology方法模拟计算了1, 1-二氨基-2, 2-二硝基乙烯（FOX-7）的晶体形态和结晶习性,得到特定晶面的面心距离、面积、附着能等参数,确定了其形态学上重要的生长晶面及其表面结构。建立了双层结构模型,采用分子动力学模拟计算了溶剂分子和FOX-7主要生长面之间的相互作用,研究了溶剂效应对FOX-7溶液结晶过程中晶体形貌的影响,为FOX-7溶液结晶过程中溶剂的选择提供理论依据。采用实验的方法,在N,N-二甲基酰胺/丙酮结晶体系条件下重结晶制备了FOX-7,其外形规则、棱角圆润、长径比变小,与模拟结果具有一致性。     

语音情感识别的研究进展

情感在人类的感知、决策等过程扮演着重要角色.长期以来情感智能研究只存在于心理学和认知科学领域,近年来随着人工智能的发展,情感智能跟计算机技术结合产生了情感计算这一研究课题,这将大大的促进计算机技术的发展.情感自动识别是通向情感计算的第一步.语音作为人类最重要的交流媒介,携带着丰富的情感信息.如何从语音中自动识别说话者的情感状态近年来受到各领域研究者的广泛关注.本文从语音情感识别所涉及的几个重要问题出发,包括情感理论及情感分类、情感语音数据库、语音中的情感特征和语音情感识别算法等,介绍了当前的研究进展,并讨论了今后研究的几个关键问题.     

A cascading failure model for interdomain routing system

There have been many researches on border gateway protocol (BGP) security, most of which mainly focused on how to enhance the security of the BGP protocol or the interdomain routing system. However, few works studied the vulnerabilities especially the production mechanism of security events in the interdomain routing system. It takes many obstacles to understand and improve the security of the interdomain routing system. This paper explores the cascading failure phenomenon of the interdomain routing system. First, we devise a state machine to describe the state transition of BGP nodes and then give a detailed analysis of the BGP failure. Second, on the basis of the preferential attachment characteristic, we propose a cascading failure model for the interdomain routing system, which depicts the production mechanism of cascading failure, and introduce two evaluating indicators, the proportion of failed nodes and the proportion of failed links, to assess the scale of cascading failure. Furthermore, we apply the cascading failure model to display two different cascading failure scenes. The experimental results show that random failure has less influence on the interdomain routing system, while its robustness against hostile attack is weak. Copyright ©2011 John Wiley & Sons, Ltd.     

应用AWE技术快速分析线面宽带电磁特性

利用渐近波形估计(AWE)技术分析了线面连接混合结构宽频带电磁特性。为了保证线面连接处电流的连续性,采用线-三角形模型,导体部分和导线部分与线面连接处分别采用不同的基函数;推导出线面连接混合结构的阻抗矩阵及其高阶导数,通过矩量法(MoM)求解线面积分方程得到给定频率点电流分布,然后应用AWE 技术快速有效地实现了导体和线结构在宽频带内的电流分布,得到整个线-面连接混合结构的输入阻抗和辐射方向 图,通过与MoM 结果相比,验证了该方法在分析线面混合结构宽带问题方面的高效性。     

Thin-film reactions during diffusion soldering of Cu/Ti/Si and Au/Cu/Al<Subscript>2</Subscript>O<Subscript>3</Subscript> with Sn interlayers

The multilayer thin-film systems of Cu/Ti/Si and Au/Cu/Al₂O₃ were diffusion-soldered at temperatures between 250°C and 400°C by inserting a Sn thin-film interlayer. Experimental results showed that a double layer of intermetallic compounds (IMCs) η-(Cu_0.99Au_0.01)₆Sn₅/δ-(Au_0.87Cu_0.13)Sn was formed at the interface. Kinetics analyses revealed that the growth of intermetallics was diffusion-controlled. The activation energies as calculated from Arrhenius plots of the growth rate constants for (Cu_0.99Au_0.01)₆Sn₅ and (Au_0.87Cu_0.13)Sn are 16.9 kJ/mol and 53.7 kJ/mol, respectively. Finally, a satisfactory tensile strength of 132 kg/cm² could be attained under the bonding condition of 300°C for 20 min.     

基于ZCPA参数的语音情感识别研究

主要讨论了情感语音特征参数的提取、语音情感的分类、语音资料的获取和应用连续隐马可夫模型进行情感识别等,重点比较了ZCPA特征参数和传统特征参数在不同噪声环境下的识别率,实验表明,在不同的噪声环境下,采用ZCPA特征的语音情感的识别效果较好,识别率也没有明显的下降。     

大功率白光LED封装技术对器件寿命的影响

通过功率LED器件封装工艺技术的改进来降低芯片结温,从而减缓器件光衰速率,延长其预期的工作寿命时间。对用于封装的关键原材料的选取进行了对比实验,指出了采用纳米级材料改进导热可降低热阻,论述了正确选用混胶材料和工艺,可以减缓器件光衰速率,达到在较高的环境温度条件下,器件使用寿命大于50 000 h。论述了器件芯片的结温对光、电、色性能的影响和不同结温其预期工作寿命时间也不同的关联性。     

Detrended Fluctuation Analysis of the Human EEG during Listening to Emotional Music

A nonlinear method named detrended fluctuation analysis （DFA） was utilized to investigate the scaling behavior of the human electroencephalogram （EEG） in three emotional music conditions （fear, happiness, sadness） and a rest condition （eyes-closed）. The results showed that the EEG exhibited scaling behavior in two regions with two scaling exponents β1 and β2 which represented the complexity of higher and lower frequency activity besides α band respectively. As the emotional intensity decreased the value of β1 increased and the value of β2 decreased. The change of β1 was weakly correlated with the ＇approach-withdrawal＇ model of emotion and both of fear and sad music made certain differences compared with the eyes-closed rest condition. The study shows that music is a powerful elicitor of emotion and that using nonlinear method can potentially contribute to the investigation of emotion.     

结合音质特征和韵律特征的语音情感识别

为了提高语音情感的正确识别率,在情感语音韵律特征的基础上,提出情感语音音质特征的提取.结合音质特征参数和韵律特征参数,采用支持向量机分类器实现汉语普通话生气、高兴、悲伤和惊奇四种主要情感类型语音的情感识别.实验结果表明,语音音质特征参数和韵律特征参数相结合取得的情感平均正确识别率为88.1%,比单独使用韵律特征参数高出6%.可见,语音音质特征是一种较有效的情感特征参数.     

运用高斯混合模型识别动物声音情绪

针对动物的情绪识别问题,提出高斯混合模型在动物声音情绪识别上的应用方法。利用语音信号处理与机器学习技术,提取动物声音信号的过零率、共振峰、梅尔 频率倒谱系数3种描述动物情绪的特征参数。采用高斯混合模型对采集到的动物声音信号训练样本进行聚类分析,计算测试样本后验概率,实现动物情绪的自动识别。通过分析特征参数的权重系数组合、高斯混合数目对识别率的影响来择选最优参数。实验结果表明,经参数优化后的高斯混合模型可将动物声音情绪的识别率由84.25%提高至96.67%。