不同因素对认知诊断DINO模型诊断准确率的影响

本文探究不同因素对确定性输入噪声"或"门模型(DINO)判准率的影响。模拟实验表明:DINO模型更适用于离散型属性层级结构;测验长度的合理增加有助于提高诊断的准确率;DINO模型对属性层级结构不敏感;认知属性个数的增加会降低DINO模型的诊断准确率,实际应用中建议认知属性个数控制在6个以下。     

甲型 H1N1 流感 1126 例回顾性临床分析

为探讨甲型H1N1流感轻症病例与普通流感不同之处。采用回顾性分析2009年9月至2010年4月我校1126例甲型H1N1流感患者的临床资料。显示暴发时间与普通流感季节不同。早期血常规检查结果显示：92．4％病例嗜酸粒细胞百分率减低,83．0％病例淋巴细胞百分率减低,71．6％病例单核细胞百分率增高。临床表现及治疗方法与普通流感无明显区别。发现甲型H1N1流感患者早期血常规检查可显示与普通流感不同之异常改变。     

Local synthesis of carbon nanotubes for direct integration in Si microsystems - design considerations

The integration of nanomaterials such as carbon nanotubes （CNTs） into microsystems is highly desirable, in order to make use of the unique nanomaterial properties in real devices. However, the CNTtomicrosystem integration is challenging to implement in a manufacturable, cost effective industrial process. This paper presents our work towards a process for making complete, integrated CMOS / MEMS systems with integrated CNT. We demonstrate the feasibility of the process, using roomtemperature process ing, lowcost equipment and consumables, and electrical control with automation possibilities. CNTs are directly integrated at the desired positions in the Si microsystem, forming closed Si / CNT / Si circuits. We explore different designs with the aim to obtain uniform and welldefined CNT synthesis conditions, and show that simplified designs can perform comparably to more complex ones. The Si / CNT / Si circuits obtained can show rectifying （Schottky like） or nearohmic behavior. Gas sensing possibilities are demonstrated, indicating the possibility of monitoring aging/ fermenting of food. Functionalization of CNTs is demon strated, using thermal evaporation of Sn and Pd, opening for selective and sensitive sensors for various gases and ana lytes. Detailed microscopic characterization of the obtained CNTs are presented.     

Wafer-level SLID bonding for MEMS encapsulation

Hermetic packaging is often an essential requirement to enable proper functionality throughout the device＇s lifetime and ensure the optimal performance of a micro electronic mechanical system （MEMS） device. Solid-liquid interdiffusion （SLID） bonding is a novel and attractive way to encapsulate MEMS devices at a wafer level. SLID bonding utilizes a low-melting-point metal to reduce the bonding process temperature; and metallic seal rings take out less of the valuable surface area and have a lower gas permeability compared to polymer or glass- based sealing materials. In addition, ductile metals can adopt mechanical and thermo-mechanical stresses during their service lifetime, which improves their reliability. In this study, the principles of Au-Sn and Cu-Sn SLID bonding are presented, which are meant to be used for wafer-level hermetic sealing of MEMS resonators. Seal rings in 15.24 cm silicon wafers were bonded at a width of 60 gin, electroplated, and used with Au-Sn and Cu-Sn layer structures. The wafer bonding temperature varied between 300 ℃ and 350 ℃, and the bonding force was 3.5 kN under the ambient pressure, that is, it was less than 0.1 Pa. A shear test was used to compare the mechanical properties of the interconnections between both material systems, in addition, important factors pertaining to bond ring design are discussed according to their effects on the failure mechanisms. The results show that the design ofmetal structures can significantly affect the reliability of bond rings.     

Effect of substrates and underlayer on CNT synthesis by plasma enhanced CVD

Due to their unique thermal, electronic and mechanical properties, carbon nanotubes （CNTs） have aroused various attentions of many researchers. Among all the techniques to fabricate CNTs, plasma enhanced chemical vapor deposition （PECVD） has been extensively developed as one growth technique to produce verticallyaligned car bon nanotubes （VACNTs）. Though CNTs show a trend to be integrated into nanoelectromechanical system （NEMS）, CNT growth still remains a mysterious technology. This paper attempts to reveal the effects of substrates and un derlayers to CNT synthesis. We tried five different substrates by substituting intrinsic Si with high resistivity ones and byincreasing the thickness of SiO2 insulativity layer. And also, we demonstrated an innovative way of adjusting CNT den sity by changing the thickness of Cu underlayer.     

Simultaneous optimization of multiple performance characteristics in WEDM for machining ZC63/SiCp MMC

Abstract The compliance of an integrated approach, principal component analysis （PCA）, coupled with Tagu chi＇s robust theory for simultaneous optimization of cor related multiple responses of wire electrical discharge machining （WEDM） process for machining SiCp rein forced ZC63 metal matrix composites （MMCs） is investi gated in this work. The WEDM is proven better for its efficiency to machine MMCs among others, while the particulate size and volume percentage of SiCp with the composite are the utmost important factors. These improve the mechanical properties enormously, however reduce the machining performance. Hence the WEDM experiments are conducted by varying the particulate size, volume fraction, pulseon time, pulseoff time and wire tension. In the view of quality cut, the most important performance indicators of WEDM as surface roughness （Ra）, metal removal rate （MRR）, wire wear ratio （WWR）, kerf （Kw） and white layer thickness （WLT） are measured as respon ses. PCA is used as multiresponse optimization technique to derive the composite principal component （CPC） which acts as the overall quality index in the process. Consequently, Taguchi＇s S/N ratio analysis is applied to optimize the CPC. The derived optimal process responses are confirmed by the experimental validation tests results. The analysis of vari ance is conducted to find the effects of choosing process variables on the overall quality of the machined component.The practical possibility of the derived optimal process conditions is also presented using SEM.     

The Research of Cooperative Learning Effects on College Students＇ Learning Anxiety

Since Krashen put forward the Affective Filter Hypothesis, more and more concern has been paid to the anxiety problem in Second and foreign language teaching and learning. Meanwhile, CL （cooperative learning） has gained much attention in recent years, both at home and abroad. Most researches （Oxford ＆ Ehrman, 1993; Kagan, 1994; Slavin, 1995） on CL indicated that CL is a classroom procedure which can lower anxiety and improve learning outcomes. Although the researches abroad have suggested that CL has a positive impact on reducing foreign language learning anxiety, few empirical researches on CL have been conducted in China. Moreover, according to the author＇s observation, anxiety is most obvious in oral English activities. Therefore, this thesis attempts to investigate some Chinese non-English freshmen＇s foreign language learning anxiety. Two classes are involved in the study： one as the experimental class instructed with CL method, the other as the control class taught with the traditional teaching method. By using a classical instrument, the FLCAS （foreign language classroom anxiety scale）, this study examined the subjects＇ foreign language learning anxiety. According to the analysis and comparison of the first and second FLCAS, the author finds CL has a significant effect on reducing students＇ foreign language learning anxiety.