基于协同机制的多元化课堂教学模式探索

针对当前课堂教学以教师为主导的灌输式教学模式的弊端,本文提出基于师生协同机制的多元化课堂教学模式。此模式将课程教学分为基础知识讲授、知识体系构建和拓展、理论知识应用和创新三个阶段,各个阶段采用不同课堂教学方法,并在课堂教学过程中关注学生的平时学习过程。以信息类专业基础课程"模拟电子技术"为样本,我们对此多元化教学模式进行了实践,教学效果良好。     

Preparation of polypropylene/poly(styrene-co-(butyl methacrylate)) nanoblends by diffusion and subsequent copolymerization of monomers in isotactic polypropylene pellets

The diffusion and subsequent copolymerization of styrene(St)/butyl methacrylate(BMA) mixed monomers in i PP pellets to prepare copolymer nanoblends were investigated. The diffusion step was carried out at 90 ℃ for 2 h in water, and the copolymerization was initiated by the addition of BPO with the aid of a small amount of St. The diametrical distributions of both St and BMA units and their ratio St/BMA were investigated by micro FTIR. Both St and BMA can diffuse into the centres of i PP pellets. The diametrical distribution of St/BMA ratio is constant in all the copolymer blends. The copolymer composition depends on the comonomer feed ratio. The molecular weights of the copolymers were measured by GPC after extraction with tetrahydrofuran. The phase morphology of the copolymer blends was investigated by FESEM, showing the average particle sizes of less than 100 nm. DSC measurements show that the diffusion and subsequent copolymerization of St/BMA monomers only occur in the amorphous regions of i PP pellets.     

Effects of electrically inert fillers on the properties of poly(<Emphasis Type="Italic">m</Emphasis>-xylene adipamide)/multiwalled carbon nanotube composites

The effects of three types of electrically-inert fillers, calcium carbonate (CaCO₃), talc and glass fiber (GF), on electrical resistivity, crystallization behavior and dynamic mechanical properties of poly(m-xylene adipamide) (MXD6)/multiwalled carbon nanotube (MWCNT) composites are investigated. The electrical resistivity of MXD6/MWCNT composites is significantly reduced with the addition of inert fillers due to the volume-exclusion effect that leads to increased effective concentration of MWCNTs in MXD6 matrix and also due to improved MWCNT dispersion. The crystallization temperature of MXD6 increases with the addition of MWCNTs, indicating that MWCNTs can act as nucleating agent and induce crystallization of MXD6. The incorporation of inert fillers has no further effect on crystallization behavior of MXD6, but significantly improves the storage modulus of MXD6/MWCNT composite, demonstrating that CaCO₃, talc and GF filled MXD6/MWCNT composites are very promising materials with not only improved electrical property but also excellent mechanical properties.     

全数字低温漂差动电容检测技术

为降低微小差动电容检测电路的复杂度，提高检测结果的温度稳定性，提出了一种结构简单，无总移相器、滤波器、解调器的全数字检测硬件平台；然后以此硬件平台为基础，设计了检测结果与检测激励信号幅值无关，无总稳幅及温度补偿电路的检测算法。将该技术应用于某差动电容型电子水平仪进行一次启动长期稳定性试验，结果表明在连续24 h内温度变化达12℃时，水平仪的输出变化不超过±1个字（±0.5″），具有优异的温度稳定特性。该技术还可应用于其他任意采用单频正弦信号进行激励的微弱信号检测，如动调陀螺信号检测、微位移传感器信号检测等。     

微波消解法测定饲料骨粉中磷

利用微波加热技术,在密封增压罐内消解饲料试样,优选出酸消解体系、消解时间、酸用量等最佳条件,比色法测磷。该法快速、经济、准确。     

基于模糊神经网络的网络业务量预测研究

利用神经网络(NN)的自学习能力以及模糊逻辑的动态性和及时性等特点,将模糊逻辑和 NN 有机地结合起来,构造出了五层模糊神经网络(FNN),并用训练 NN 的相应学习算法-BP 算法来训练网络。本文将 FNN 用于网络自相似业务预测研究中,并与单纯的 NN 算法相比较。仿真结果表明,FNN 能很好地预测复杂网络业务,与传统的 NN 算法相比,不仅收敛速度快,且得到更好的预测效果。本文为复杂网络业务流量预测研究提供了一种有效途径。     

GPS标准现状及体系分析

GPS是目前技术最先进、应用最广泛的全球卫星导航定位系统,随着GPS技术及产业化发展,国内外发布了大量的GPS相关标准。运用分类、归纳和比较等方法,分析了GPS标准体系结构和GPS标准内容。通过对中美两国GPS标准体系结构分析,得出了GPS系统标准体系由通用基础标准、工程标准和应用标准组成。在此基础上针对COMPASS的发展建设提出了建立COMPASS标准体系结构以及对于具体标准内容制定的建议。     

电源管理芯片中热关断电路的设计

为了防止芯片过热,文章提出了两种温度检测技术：利用PTAT电流的正温度特性或利用PN结的负温度特性.在此基础上,设计出一种低功耗、具有迟滞功能的热关断电路：电路结构非常紧凑,采用1.5μm的P衬N阱数模混合1P2M BiCMOS工艺.Hspice仿真结果表明：当温度超过150℃时,电路输出发生翻转,禁止芯片工作;当温度降至115℃时,恢复芯片工作.该电路的最大工作电流不超过150μA,能很好地抑制由于电源电压和工艺参数变化造成的热关断阈值点的漂移,适用于各种电源管理芯片.     

全光纤化高效Er3+-Yb3+共掺光纤放大器的实验研究

对全光纤化高功率Er<'3+>-Yb<'3+>共掺光纤(EYDF)放大器进行了实验研究.采用小芯径双包层EYDF作为增益介质,多模高功率915 nm半导体激光器作为泵浦源,实现了EYDF放大器的全光纤化.对分布反馈(DFB)激光器输出的窄带信号进行放大,得到了斜率效率约为27.2%、最高2.14 W的高功率输出;实验中...     

固相萃取-液相色谱-串联质谱法测定猪栏废水中10种抗生素

应用固相萃取-液相色谱-串联质谱法测定养猪废水中10种抗生素的含量。水样由盐酸调节pH至2.5~4.0,流经Oasis HLB固相萃取柱富集后再用甲醇洗脱。以Aglient eclipse XDB C18色谱柱为分离柱,以不同体积比的0.1%(体积分数)甲酸溶液和乙腈混合液为流动相进行梯度洗脱,采用电喷雾正离子源多反应监测模式检测。10种抗生素在一定的质量浓度范围内与其峰面积呈线性关系,方法的检出限(3S/N)在0.03~3.5μg·L-1之间。加标回收率在53.2%~104%之间,测定值的相对标准偏差(n=6)在0.5%~6.3%之间。