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Simulation Investigation on Optical and Electrical Properties of Carbon Nanotube in Terahertz Region
HE Xiao-Yong FU Xiao-Nan 《理论物理通讯》2009,51(1):161-164
Under the framework of Maxwell-Garnett (M-G) model, the optical and electrical properties of singlewalled carbon naotube (SWCNT), double-walled carbon nanotube (DWCNT) and hydrogen-doped carbon nanotube (H-doped GNT) in terahertz (THz) region have been investigated. It has been found that as frequency increases the loss tangent and conductivity show a peak. The loss tangent and conductivity of SWCNT is larger than that of DWCNT and H-doped CNT. The loss tangent and conductivity increase with the increases of filling factor and the decreases of geometrical factor. 相似文献
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控制阀在工业控制领域扮演十分重要的角色,但目前国内对控制阀性能测试评估系统的研究十分薄弱,常规的仪器仪表很难精确测试控制阀的性能。本文基于NI compactRIO硬件、各类传感器以及Labview软件开发设计了一套控制阀性能测试评估系统,该系统实现了控制阀的在线测试和功能评估,并且可将控制阀各项性能指标评估结果汇集于一张类似体检单的报表显示。采用该系统对某公司的直通气开式薄膜调节阀S9044进行了性能测试评估,实验结果表明,该系统能够精确地测试出调节阀的各项性能指标,且系统软件交互界面良好、扩展性强、精度高。 相似文献
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A pulsed master-oscillator fiber power amplifier system with near diffraction-limited output by use of China-made large-mode-area fiber and a (2 + 1) × 1 multimode combiner is reported. The effect of the seed power on the amplification performance is found. For the seed power, there exists a range within which the pulsed fiber amplifier can operate safely and reliably at a certain pump power. With the seed average power of 70 mW, the amplification performances of the fiber amplifier are investigated. 相似文献
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换热器空气侧换热效率低是换热器领域的难点,管翅换热器是目前应用广泛、性能较优的换热器。为了寻求更好的换热器制作材料,以铜网片替代管翅换热器的板翅片,研制三种与市售管翅换热器同等尺寸(40×80×180 mm)的网翅片换热器进行换热性能实验对比,实验结果表明:研制的网翅片换热器相比于管翅换热器,在自然对流下热阻能降低35%;在强制对流下热阻能降低75%,网翅片换热器的温升是管翅换热器的20%。 相似文献
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采用自主开发的SONG/TANG-MSR栅格/堆芯分析程序对新型钍基熔盐堆(TMSR)进行堆芯布置与燃耗分析计算。根据前期的栅格分析相关工作,TMSR采用了无铍(BeF2)燃料熔盐、氧化铍慢化剂以及碳化硅包壳,并在组件栅格初步优化分析的基础上,通过全堆芯计算对熔盐栅格进一步优化和分析,给出了堆芯三区布置方案。该方案具有较高的增殖比,负的功率系数,以及较平的温度分布。根据该堆芯方案,在考虑熔盐在线处理情况下进行了熔盐燃耗计算分析。结果表明,堆芯具有较高的增殖比、较短的倍增时间以及长期稳定运行能力。新型的钍基熔盐设计大大提高了增殖性能,同时又确保堆芯具有足够的安全性能。 相似文献
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Sintering of cubic boron nitride (cBN) with addition of A1 is carried out in the temperature range 1300-1500℃ and under the pressure 5.5 GPa. When sintered at 1300℃, a weak diffractive peak of hexagonal BN (hBN) is observed in the Al-cBN sample, indicating the transformation from cBN to hBN. No nitrides or borides of A1 are observed, which indicated that A1 does not react with cBN obviously. When the sintering temperature is increased to 1400℃, the diffractive peak of hBN disappears and new phases of A1N and A1B2 are observed, due to reactions between A1 and cBN. When the sintering temperature is further increased to 1500℃, the contents of A1N and A1B2 phases increase and the A1 phase disappears completely. 相似文献
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Dielectric Performance of Porous Methyl Silsesquioxane/Triacetyl-β-Cyclodextrin Thin Films 下载免费PDF全文
Porous methyl silsesquioxane thin films with low dielectric constant are successfully synthesized by means of the sol-gel spin-coating method. The precursor solutions are prepared by properly mixing the polymer as a matrix with different contents of triacetyl-β-cyclodextrin (TABCD) as a porogen. The chemical structure, dielectric constants, optical constants and void fraction are investigated by the ellipsometric porosimetry, Fourier transform infrared (FTIR) spectroscopy, and other methods. Influences of TABCD and methyl trimethoxysilane (MTMS) on the dielectric properties are discussed. For those samples with higher porogen loading, orientation and electronic polarizations are lower in low and high frequency regions, respectively, because of a considerably smaller number of polar molecules. The FTIR results suggest that high R value (molar ratio of H2 O to MTMS) is more advantageous for formation of cage structures and the cage/network structural ratio increases with the increasing R value. 相似文献
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固相法制备了碱土金属铝酸盐荧光粉CaAl12O19 : Eu,Mn,测试了样品的XRD及激发与发射光谱,对样品的结构及其发光性能进行了分析,并且考察了灼烧温度及Eu3+的浓度对样品发光性能的影响,对Eu3+的作用机理进行了探讨。 该荧光粉能被波长短于550 nm的蓝绿光以及紫外和近紫外光激发,其发射光谱峰值在590,615,645,657 nm,其中前两个为Eu3+的特征发射,后两个为Mn4+的2E-4 A2跃迁发射。该荧光粉的最佳烧结温度与时间分别为1 550 ℃和4 h,Eu3+的最佳掺杂摩尔分数为0.11%左右。 相似文献
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为了评估复杂冷却涡轮内部冷却结构变化对涡轮气动及传热性能的影响,本文采用气热耦合计算方法对三种具有不同内部冲击结构的高压导叶进行了研究。分析了无冲击冷却结构、冲击挡板结构以及冲击套筒结构对涡轮气动及传热性能的影响规律。结果表明:在气动性能方面,无冲击冷却结构方案总流量最大,带有冲击套筒结构方案最小,同时涡轮气动效率也会随着内部结构的变化而变化;在传热方面,通过对比可以发现两种冲击方案都会对叶片表面最大温度进行降低,但冲击套筒结构方案同时还能够降低叶片表面平均温度。 相似文献
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硅泡沫垫层材料同其他高分子材料一样同样存在老化的问题,在使用和贮存过程中会受到温度、湿度、氧化、应力等因素的影响而发生老化,性能劣化。因此,研究其相对薄弱环节的贮存老化性能是很重要的。 相似文献