片式电阻保护浆料的制备

通过与日本样进行对比试验,研究了片式电阻保护浆料的制备工艺及要求。分析了玻璃组成和浆料配方对元件电阻值漂移的影响,并对其保护机理进行了探讨。制备的浆料达到日本样技术指标的要求。利用4号玻璃组分的1MΩ片电阻的阻值漂移率最小为0.9%     

新的Schiff碱-双(2,3-二甲氧基苯甲醛)缩联苯胺的合成与光谱研究

以2,3-二甲氧基苯甲醛和联苯胺为原料,在无水甲醇溶剂中合成了一种新的Schiff碱,收率为86.0%.反应的最佳条件是2,3-二甲氧基苯甲醛与联苯胺的比例为3:1,反应时间为1h,反应温度为30℃.这种新的Schiff碱结构利用IR和UV光谱表征.     

一种四象限14位乘法型D/A转换器设计

设计了一种14位乘法型D/A转换器。采用高3位温度计编码、低11位二进制编码的分段电流模R-2R电阻网络结构,规避了高分辨率二进制电流模R-2R电阻网络开关尺寸大、版图匹配难度大的缺点。基于混合信号CMOS工艺进行了流片,实测DNL在±0.5 LSB以内,INL在±0.8 LSB以内。该D/A转换器适用于工业控制、仪器仪表等领域。     

永磁同步电机矢量控制系统的标幺化设计

在永磁同步电机的数字控制系统中,由于受到控制器位数的限制,采用参数实际值进行计算往往存在运算精度低、数据容易溢出等问题。为此,文中研究了一种永磁同步电机矢量控制系统的标幺化设计方法,并基于TI公司的TMS320F2812定点型DsP进行了实验研究,实验结果验证了该方法的可行性及有效性。     

Asymmetric Schiff Base (N 2 O 3 ) Complexes as Ligands Towards Mn(II), Fe(III) and Co(II), Synthesis and Characterization

Heterobi- and tri-nuclear complexes [LMM'Cl] and [(LM) 2 M'](M=Ni or Cu and M'=Mn, Fe or Co) have been synthesised. The heteronuclear complexes were prepared by stepwise reactions using two mononuclear Ni(II) and Cu(II) complexes of the general formula [HLM]·1/2H 2 O, as ligands towards the metal ions, Mn(II), Fe(III) and Co(II). The asymmetrical pentadentate (N 2 O 3 ) Schiff-base ligands used were prepared by condensing acetoacetylphenol and ethylenediamine, molar ratio 1 1, to yield a half-unit compound which was further condensed with either salicylaldehyde or naphthaldehyde to yield the ligands H 3 L 1 and H 3 L 2 which possess two dissimilar coordination sites, an inner four-coordinate N 2 O 2 donor set and an outer three-coordinated O 2 O set. 1 H NMR and IR spectra indicate that the Ni(II) and Cu(II) ions are bonded to the inner N 2 O 2 sites of the ligands leaving their outer O 2 O sites vacant for further coordination. Different types of products were obtained according to the type of metal ion. These products differ in stoichiometry according to the type of ligand in the parent compound. Electronic spectra and magnetic moments indicate that the structures of the parent Ni(II) and Cu(II) complexes are square-planar while the geometry around Fe(III), Mn(II) and Co(II) in their products are octahedral as elucidated from IR, UV-visible, ESR, 1 H NMR, mass spectrometry and magnetic moments.     

透反液晶显示器在头盔显示器中的应用

在强光条件下头盔显示器高亮度显示带来的视觉模糊问题较为突出,透反液晶显示器能够较好地解决这个问题,设计了光敏电阻控制电路感知外界光线强度,控制透视模式和反射模式的切换,并给出了电路安装的方案,仿真试验取得了较好的效果,具有良好的应用前景.     

微型薄膜电阻的制备及研究

将具有优异特性的碳纳米管（CNTS）与负性感光胶（SU-8 2002）混合得到复合材料,将不同比例的碳纳米管通过超声工艺分散到SU-8 2002感光胶中,通过UV-LIGA加工工艺,热压处理后实现了微型电阻的快速制备。对复合薄膜电阻的性能进行测试,测试结果表明复合薄膜电阻率随着碳纳米管比例的增加而减小,当碳纳米管的比例为12%时,电阻率减小到0.06 ,复合材料达到逾渗阈值,频率小于1.2GHz时,电阻值的变化范围小于5%,为快速制备微型电阻提供了新的方法。     

Base-catalyzed cross coupling of secondary alcohols and aryl-aldehydes with concomitant oxidation of alcohols to ketones: An alternative route for synthesis of the Claisen-Schmidt condensation products

Base-catalyzed C–C cross coupling of secondary alcohols and aryl-aldehydes was achieved, when an alcoholic solution of an aryl-aldehyde was stirred under reflux for 45 h in the presence of a catalytic (20 mol%) amount of K₂CO₃. The consistent formation of α,α′-bis-(benzylidene) alkanones was obtained in moderate to good yields using various secondary alcohols and substituted aryl-aldehydes. Herein, α,α′-bis-(benzylidene)alkanones, which are the classical products of Claisen-Schmidt (cross aldol) condensation, have been synthesized via an alternative strategy using secondary alcohols. Bis-(benzylidene) alkanones are an integral part of various drug regimes and the production of bis-(benzylidene) alkanones without using any precious metal is a major outcome of the present reaction.     

钌基厚膜电阻传导模型初探

介绍钌基厚膜电阻的三种传导模型。三种模型都可以得到较满意的R—V曲线，不足处是链模型得出电阻率和导电相粒子形状及尺寸的关系和实验事实不符；有效介质模型不能反映厚膜电阻形成过程中众多因素的影响；渗透模型很多参数的获得有赖经验公式。渗透模型能反映烧结过程中更多因素的影响，并可解释方阻与导电相粒度及峰值温度的变化关系。