Motor Imagery EEG Fuzzy Fusion of Multiple Classification

Due to the volume conduction, electroencephalogram (EEG) gives a rather blurred image of brain activities. It is a challenge for generating satisfactory performance with EEG. This paper studies the multiple areas fusion of EEG classifiers to improve the motor imagery EEG classification performance. Two feature extraction methods are employed to extract the feature from three different areas of EEG. One is power spectral density (PSD), and the other is common spatial patterns (CSP). Classifiers are designed based on the well-known linear discrimination analysis (LDA). The fusion of the individual classifiers is realized by means of the Choquet fuzzy integral. It is demonstrated that the proposed method comes with better performance compared with the individual classifier.     

种含氮杂环类药物的手性色谱拆分及其制剂中对映体含量的测定

采用纤维素-三(4-甲基苯甲酸酯)手性固定相,利用反相高效液相色谱法研究了奥沙西泮、吡格列酮和罗格列酮3种含氮杂环类手性药物的色谱拆分行为.考察了流动相组成、pH值和柱温对3种药物对映体分离的影响,并对其拆分机理进行了探讨.结果表明,采用甲醇-水为流动相,通过添加醋酸或氨水调节pH值和控制柱温,可使3种药物的对映体得到完全分离(Rs＞1.5),根据各自优化的色谱条件建立了这3种手性药物对映体的分析方法,并应用于其制剂的含量测定,方法简单、可靠.     

顺式、反式氯氰菊酯和烯唑醇对映异构体的手性拆分

将纤维素-三(3,5-二甲基苯基氨基甲酸酯)(CDMPC)涂敷于氨丙基硅胶上制备成高效液相色谱(HPLC)手性固定相,对手性农药顺式、反式氯氰菊酯和烯唑醇对映异构体在正相条件下进行了手性拆分。分别以正己烷和石油醚为流动相,考察改性剂的含量;在正己烷流动相条件下考察了色谱柱长度、温度对拆分效果的影响。试验结果显示,改性剂含量的减少、长色谱柱及降低温度均有利于对映体的分离。该手性固定相对顺式、反式氯氰菊酯具有非常强的立体选择性,对烯唑醇也有较好的拆分能力。     

0.5mm间距CSP/BGA器件无铅焊接工艺技术研究

芯片级封装器件因其小尺寸、低阻抗、低噪声等优点广泛应用于电子信息系统中.从器件封装、印制板焊盘设计、焊膏印刷、贴装以及回流焊接等方面探讨了0.5 mm间距CSP/BGA器件无铅焊接工艺技术.     

十字阵短时宽带声源实时定向算法

面向短时宽带声源实时定向问题,提出了一种基于互功率谱时延估计的十字阵定向优化算法。针对该方法估计结果离散且呈不均匀分布的特点,将观测平面划分为四个测量区域,并利用不同阵元组合分别处理,解决实时性与估计成功率的矛盾;依据互相关函数的特点,设计了若干判断准则,排除由于数据取样短造成的异常时延估计,改善算法的可靠性;采用频域插值方法,一定程度上提高时延估计精度,从而提高定向精度。MATLAB仿真和DSP系统实验表明,这种方法在实际应用中有效提高了对短时宽带声源定向的性能。     

迎接21世纪的表面组装技术

详细地介绍了先进集成电路封装的发展,概括叙述了适用于先进封装表面组装工艺技术的最新发展动向,预测了２１世纪表面组装技术的发展趋势。     

Board level reliability assessment of chip scale packages

A large program had been initiated to study the board level reliability of various types of chip scale package (CSP). The results on six different packages are reported here, which cover flex interposer CSP, rigid interposer CSP, wafer level assembly CSP, and lead frame CSP. The packages were assembled on FR4 PCBs of two different thicknesses. Temperature cycling tests from −40°C to +125°C with 15 min dwell time at the extremes were conducted to failure for all the package types. The failure criteria were established based on the pattern of electrical resistance change. The cycles to failure were analyzed using Weibull distribution function for each type of package. Selected packages were tested in the temperature/humidity chamber under 85°C/85%RH for 1000 h. Some assembled packages were tested in vibration condition as well. In all these tests, the electrical resistance of each package under testing was monitored continuously. Test samples were also cross-sectioned and analyzed under a Scanning Electronic Microscope (SEM). Different failure mechanisms were identified for various packages. It was noted that some packages failed at the solder joints while others failed inside the package, which was packaging design and process related.     

Enthalpy-entropy compensation effect in gas chromatographic enantiomeric separation

In this paper, the enthalpy-entropy compensation effect in the enantiomeric separation by modified cyclodextrins (CD) and diamide chiral stationary phase (CSP) gas chromatography was investigated using the method of plotting △(△H) versus △(△G) rhm combined with t-test statistic analysis. The investigated racemates cover α-phenylethylamine and its analogs, 2-alkylamines, chiral acyclic alcohols, halogenated arylethanediol-1, 2-diperfluoropropionates, amino acid and its analogs, and two series of compounds containing chloro and bromo substituents. From the compensation analysis results, the effects of the diluent composition in the investigated chiral stationary phases, the size and the modified groups on investigated cyclodextrins, the derivatization methods and the groups attached to the stereocenters on enantiomeric separation mechanisms were all discussed.     

芯片尺寸封装技术

芯片尺寸封装（ＣＳＰ）技术是近年来发展最为迅速的微电子封装新技术。文中介绍了该技术的基本概念、特点、主要类型及其应用现状和展望。     

超薄型圆片级芯片尺寸封装技术

ShellCase公司的圆片级封装技术工艺,采用商用半导体圆片加工设备,把芯片进行封装并包封到分离的腔体中后仍为圆片形式。圆片级芯片尺寸封装(WL-CSP)工艺是在固态芯片尺寸玻璃外壳中装入芯片。玻璃包封防止了硅片的外露,并确保了良好的机械性能及环境保护功能。凸点下面专用的聚合物顺从层提供了板级可靠性。把凸点置于单个接触焊盘上,并进行回流焊,圆片分离形成封装器件成品。WL-CSP封装完全符合JEDEC和SMT标准。这样的芯片规模封装(CSP),其测量厚度为300μm-700μm,这是各种尺寸敏感型电子产品使用的关键因素。