无触点开关在炉温控制器的应用

电路采用可控硅代替交流接触器,另设向可控硅烧损检测电路,实现无噪音,无振动控制,提高了控制精度,延长了控温仪表的使用寿命。     

无触点开关在炉温控制器中的应用

电路采用可控硅代替交流接触器,另设双向可控硅烧损检测电路,实现无噪音、无振动控制,提高了控制精度,延长了控温仪表的使用寿命。     

电子灭弧技术的原理与应用

1电子灭弧模块的工作原理 随着可控硅技术的发展,利用可控硅元件作为电子开关,已经实现了无触点控制,但是可控硅元件在导通时有约1.2V的电压降,在大电流状态下工作的可控硅,热损耗问题就十分突出.电子灭弧模块是以双向可控硅为工作主回路,将交流接触器的触点间的电压控制在极低范围内,从根本上消除产生电弧的原因.     

大功率交流稳流电源的研制

采用单片机控制双向可控硅作为电子开关所组成的电压分节网络,组成新颖快速的电子调压器;由于双向可控硅过零触发,所以其输出是不失真的完整正弦波;再用单片机组成反馈控制系统,从而找到了交流稳流的新方法,研制出一个大功率交流稳流电源.     

微机控制的可控硅交流调功器

本文重点介绍微机控制的可控硅交流调动器的设计原理。     

可控硅桥两侧电量的数理方程组及交流侧的等值谐波导纳计算

作者根据稳态开关函数和脉动开关函数理论,建立了一整套用来表征可控硅桥两侧电量之间关系的数理方程式组,并由此导出了轧机可控硅桥交流侧的等值谐波导纳的计算公式.     

一种新的电流型可控硅交流电机调速电源

该电流型可控硅交流电机调速电源,采用150°导通角,具有低百分比的高次谐波,优于120°导通角的调速电源。主电路采用可控硅整流和辅助可控硅关断的三相桥式逆变器。逆变主触发信号由单板机控制,并与同步脉冲列相“与”而成,较好地解决了脉冲变压器的饱和问题。实验所得的电流波形经谐波分析证明了预期的效果。本电源用于交流电机的调速,可以降低电机的损耗。     

玻璃纤维生产线温度自动控制系统

本文论述了玻璃纤维建筑材料生产中温度自动控制系统电路的构成和工作原理。用双向可控硅组成交流调压电路,用KC05可控硅移相触发集成电路控制可控硅的导通角,调节预置电位器可以选择输出电压或电流,并自动稳定系统的输出电压或电流,以便间接控制和稳定熔炼坩埚或拉丝铂管内的作业温度。     

新型交流调压控制系统及应用

】本文介绍一种用于可控硅三相交流调压电路的新型控制系统，同时给出了一个应用实例     

交流电动机可控硅串级调速系统机械特性曲线的简便绘制和动态模型的简便线性化方法

关于交流机可控硅串级调速性能的讨论已有不少文献,但对它的机械特性的绘制尚无简便方法,对它的动态数学模型及其线性化的讨论尚很少见。本文先讨论交流机可控硅串级调速具有SCR-D性质,然后提出一种绘制串调机械特性曲线的简便方法——相对值曲线。最后对它的动态数学模型指出一般工程线性化的简便方法。     

一种在弱酸溶液中采用金属辅助湿法化学刻蚀黑硅的新方法

为降低黑硅材料的成本,将太阳电池级单晶硅片浸入含有氯金酸(HAuCl4)的草酸/氢氟酸(H2C2O4/HF)混合水溶液中做刻蚀.利用扫描电子显微镜(SEM)和紫外—可见—近红外分光光度计对表面形貌和反射光谱进行了表征与测量.结果表明:样品表面具有网格状陷光结构,在350~2 500nm波段平均反射率约为11.3%.     

Chemical reduction of three-dimensional silica micro-assemblies into microporous silicon replicas

The carbothermal reduction of silica into silicon requires the use of temperatures well above the silicon melting point (> or =2,000 degrees C). Solid silicon has recently been generated directly from silica at much lower temperatures (< or =850 degrees C) via electrochemical reduction in molten salts. However, the silicon products of such electrochemical reduction did not retain the microscale morphology of the starting silica reactants. Here we demonstrate a low-temperature (650 degrees C) magnesiothermic reduction process for converting three-dimensional nanostructured silica micro-assemblies into microporous nanocrystalline silicon replicas. The intricate nanostructured silica microshells (frustules) of diatoms (unicellular algae) were converted into co-continuous, nanocrystalline mixtures of silicon and magnesia by reaction with magnesium gas. Selective magnesia dissolution then yielded an interconnected network of silicon nanocrystals that retained the starting three-dimensional frustule morphology. The silicon replicas possessed a high specific surface area (>500 m(2) g(-1)), and contained a significant population of micropores (< or =20 A). The silicon replicas were photoluminescent, and exhibited rapid changes in impedance upon exposure to gaseous nitric oxide (suggesting a possible application in microscale gas sensing). This process enables the syntheses of microporous nanocrystalline silicon micro-assemblies with multifarious three-dimensional shapes inherited from biological or synthetic silica templates for sensor, electronic, optical or biomedical applications.     

铁素体球墨铸铁低温冲击韧性

为了优化生产工艺,探究化学成分对低温冲击韧性影响规律,通过夏比冲击试验方法研究了三组铸态全铁素体球墨铸铁低温冲击韧性,分析了硅碳含量对低温冲击韧性影响及断口形貌。结果表明：三组试样中,冲击韧性随碳含量增多和硅含量降低而升高;冲击韧度值随着温度的降低而下降,-20 ℃下可以达到15.20 J,冲击韧度值在温度低于-40 ℃后变化不大,韧脆转变温度在-40 ℃以上。冲击断口形貌表明,随温度降低,球墨铸铁的断裂机制由韧性断裂转为韧脆混合断裂,最后变为脆性断裂。可见碳硅含量会对低温冲击韧性造成一定影响。     

运用柯布——道格拉斯函数模型解决多种生产要素最佳配合方法的探析及其应用

长期以来,我国农业技术经济理论界和实际工作者,对如何运用柯布──道格拉斯生产函数模型解决多种生产要素的最佳配合问题,即获取最大的经济效益的多种要素配合,一直未能完美地解决。笔者在从事农业技术经济学的教学与研究中,对这个问题进行了探讨与分析,比较完美地解决了这个难题,并给出了求获取最大经济效益的生产要素最适投入量的一般计算公式,这些以总收益为主线的计算公式,具有一定的理论意义和实际意义,使运用多变量的何布──道格拉斯生产函数模型解决多种生产要素最佳配合方法更具实用性和可操作性。     

溶胶-凝胶工艺对SiC粉体形貌的影响

以正硅酸乙酯(TEOS)和活性炭为原料,采用溶胶-凝胶法制备SiC前驱体,经1 400~1 600℃高温碳热还原反应合成了纯度较高的-βSiC粉体,这种粉体是由颗粒和晶须组成的混合物.通过前驱体的热重(TG)-差热(DSC)曲线分析了前驱体的热分解过程,通过X射线衍射(XRD)曲线分析了不同合成温度下的产物组织结构,并研究了无水乙醇(EtOH)与正硅酸乙酯的体积比和氨水浓度对产物形貌的影响,初步探讨了SiC颗粒和晶须的形成机理.     

Conversion of silicon carbide to crystalline diamond-structured carbon at ambient pressure

Synthetic diamond is formed commercially using high-pressure, chemical-vapour-deposition and shock-wave processes, but these approaches have serious limitations owing to low production volumes and high costs. Recently suggested alternative methods of diamond growth include plasma activation, high pressures, exotic precursors or explosive mixtures, but they suffer from very low yield and are intrinsically limited to small volumes or thin films. Here we report the synthesis of nano- and micro-crystalline diamond-structured carbon, with cubic and hexagonal structure, by extracting silicon from silicon carbide in chlorine-containing gases at ambient pressure and temperatures not exceeding 1,000 degrees C. The presence of hydrogen in the gas mixture leads to a stable conversion of silicon carbide to diamond-structured carbon with an average crystallite size ranging from 5 to 10 nanometres. The linear reaction kinetics allows transformation to any depth, so that the whole silicon carbide sample can be converted to carbon. Nanocrystalline coatings of diamond-structured carbon produced by this route show promising mechanical properties, with hardness values in excess of 50 GPa and Young's moduli up to 800 GPa. Our approach should be applicable to large-scale production of crystalline diamond-structured carbon.     

Blue light emission of porous silicon subjected to RTP treatments

Porous silicon samples were treated with the rapid thermal process (RTP) under different circumstances (N2, Ar, O2 and Air). Before and after treatments, the samples were checked by means of photoluminescence (PL) spectroscopy and Fourier transform infrared spectroscopy (FTIR). Four blue light emission peaks were found in the PL spectra of porous silicon samples subjected to the RTP treatments at temperatures above 400℃. The peak positions were found not to vary with the circumstances and temperatures of RTP treatments. It is considered that due to oxidation during the RTP treatments, the pole size of Si crystal in porous silicon decreased, resulting in the blue shift of light emission. Correlated with the Si crystal sizes discontinuous hypothesis and previous researchers' theory calculation, the PL peak positions did not vary with the RTP temperature and circumstances.     

Thermoelectric effect of silicon films prepared by aluminum-induced crystallization

Aluminum-induced crystallized silicon films were prepared on glass substrates by magnetron sputtering. Aluminum was added in the silicon films intermittently by the regular pulse sputtering of an aluminum target. The amount of aluminum in the silicon films can be controlled by regulating the aluminum sputtering power and the sputtering time of the undoped silicon layer; thus, the Seebeck coefficient and electrical resistivity of the polycrystalline silicon films can be adjusted. It is found that, when the sputtering power ratio of aluminum to silicon is 16%, both the Seebeck coefficient and the electrical resistivity decrease with the increasing amount of aluminum as expected; the Seebeck coefficient and the electrical resistivity at room temperature are 0.185-0.285 mV/K and 0.30-2.4 Ω·cm, respectively. By reducing the sputtering power ratio to 7%, however, the Seebeck coefficient does not change much, though the electrical resistivity still decreases with the amount of aluminum increasing; the Seebeck coefficient and electrical resistivity at room temperature are 0.219-0.263 mV/K and 0.26-0.80 Ω·cm, respectively.     

单晶硅片温度的拉曼光谱测定

 提出测定单晶硅片温度的拉曼散射光谱法.选择硅的520cm^-1散射带进行观测,分别记录下它的stokes和anti-stokes散射分量的强度,计算得到了硅表面激光焦斑处的温度,多次测定结果甚为一致,表明非接触拉曼光谱测定温度可与硅晶体结构的拉曼光谱研究同时进行,拉曼光谱测温法具有一定的实用性和普遍意义.     

硅波导纵向多模式分离与交叉的片上解决方案

为了解决硅纳米光子集成器件中纵向分布多模式波导的分离和交叉,提出了一种基于平面阶梯光栅和非对称定向耦合器的模式分离方案,并设计了一种带有曲面反射镜的器件,可实现多模式同时交叉.通过使用三维时域有限差分方法对器件进行仿真,结果表明:设计的平面阶梯光栅可同时分离不同的波长及模式(共9个通道),并具有低于-30 dB的串扰;曲面反射模式交叉器件可同时让3个模式进行交叉,且对所有模式均具有接近-40 dB的低串扰.