考虑SF_(6)透射率校正的GIS设备红外测温技术

红外测温技术是电力行业常用的设备故障检测手段,在气体绝缘组合电器设备(Gas Insulated Switchgear,GIS)故障诊断中有着重要应用。为提高GIS设备红外测温精度,建立了一个红外测温模型并提出一种SF_(6)透射率校正方法。首先,基于热辐射理论建立红外测温模型,并给出不同条件下的简化模型。然后,为提高温度测量精度,考虑SF_(6)透射率对红外模型测温模型输出结果的影响,给出不同条件下的SF_(6)透射率校正方法。最后,进行实际的温度测量实验,验证所建立的红外测温模型及所提SF_(6)透射率校正方法的有效性。实验结果表明,与未进行SF_(6)透射率校正的方法相比,使用所提SF_(6)透射率校正方法后温度测量精度得以提高,误差最高降低了66.7%。所提方法为电网故障检测及监控打下基础,在电网故障检测、电网安全作业等方面有着广阔的应用前景。     

外电场下C_4F_7N分子的结构与特性

C_4F_7N作为优质的SF_6环保型替代气体而备受关注.为了研究外电场对C_4F_7N分子结构和性能的影响,本文采用密度泛函明尼苏达M06-2X方法分别在6-311g(d,p)基组和aug-cc-pVTZ基组水平上对C_4F_7N分子进行优化,分析了不同外电场(0-0.040 a.u., 1a.u.=5.142×10~(11) V/m)作用下分子的结构和能量变化,外电场对分子红外光谱、ADCH电荷、偶极矩以及极化率的影响.研究结果表明:随着电场的增强,分子各键长均发生变化,其中R(1,4)、R(4,5)、R(1,12)、R(2,7)变化明显,R(1,4)、R(4,5)键长逐渐伸长,R(1,12)、R(2,7)键长逐渐缩短,分子总能量降低,偶极矩和极化率升高,C_4F_7N分子稳定性随着电场的增强而降低;分子红外光谱高频区吸收峰较为密集,且既有红移也有蓝移;ADCH原子电荷发生显著变化.     

XeCl激光触发气体开关的实验研究

通过实验研究了在自流工作状态下,XeCl准分子激光(λ=308nm,FWHM=21ns)对N_2和SF_6两种气体开关的触发特性。实验结果表明:(1)在p=0.1MPa,开关工作电压90％V_(SB)(V_(SB)为开关的自击穿电压)时,XeCl激光对N_2和SF_6两种气体开关的触发阈值约为10~8W/cm~2。(2)开关的触发延时和抖动随着激光能量和开关欠压比的增大而减小,当激光能量为33.8mJ,开关工作电压90％V_(SB)(V(SB)=36.5kV)时,充N_2开关的延时和抖动分别为85.5ns和400ps。相同欠压比下,SF_6气体开关(V_(SB)=52kV)的最小抖动度为2ns。(3)SF_6气体开关的触发延时与用T.H.Martin公式计算的结果一致。     

激光诱导击穿光谱技术定量分析SF_6中的痕量O

六氟化硫(SF_6)气体因其优良的绝缘和灭弧性能,被广泛应用于高压绝缘设备中。然而,当存在H_2O和O_2等杂质时,SF_6气体在局部放电等作用下分解成的低氟化物会进一步与杂质发生反应生成稳定的氟硫氧化物和氢化物,使得设备绝缘性能下降,危害电网安全,因此检测和分析SF_6中微水、微氧及其分解产物具有重要意义。采用激光诱导击穿光谱技术测量了SF_6中的痕量O含量。利用CaF2作为窗口材料,解决了窗口材料在不断腐蚀作用下引起的激发能量逐渐衰减以及窗口材料与SF_6气体击穿产物反应引入的污染影响测量结果的问题,消除了由激发条件改变引起的等离子体状态的变化;通过测量不同O含量的SF_6气体激光诱导击穿光谱,结合迭代小波分析对实测光谱进行基线校正和降噪处理,通过定标曲线获得了O元素检测限为38ppm。利用偏最小二乘法建立了稳定的定量分析模型,改善了定量分析模型的稳定性和精度。     

CO_2激光边带光谱仪用于SF_6分子v_3带Q支吸收谱的研究

用绝对频率精度优于1.2MHz的CO_2激光边带光谱仪记录了SF_6分子v_3带Q支的多普勒受限吸收谱,光谱范围在CO_2激光10P(16)支线中心两侧,距支线中心8.0～12.4 GHz。用内插法以<6MHz的均方误差测量了百余条跃迁谱线的频率,并标识出Q_Z、Q_R、Q_X、Q_W、Q_A等亚支的谱线,量子数J从26到83。用最小二乘法拟合实验数据得到了v_3带的部分光谱常数。     

基于改进CLAHE的SF_6红外图像增强

针对六氟化硫(SF_6)红外图像对比度低、纹理细节模糊而难以增强泄漏区域的问题,提出了基于改进限制对比度的自适应直方图均衡化(CLAHE)的SF_6红外图像增强算法。采用双边滤波将原始图像分为基础图像和细节图像;采用CLAHE算法来处理基础图像,提高泄漏区域的对比度;对细节图像进行分段线性变换和拉普拉斯变换图像,以突出图像的边缘;将两幅图像进行线性叠加以获取最终的红外图像,实现图像增强。实验结果表明,算法对SF_6红外图像泄漏区域的增强效果优于常见的几种红外图像增强算法,不仅有效地抑制了噪声和提高泄漏区域的对比度,而且突出泄漏区域的边缘,丰富了细节信息。     

基于量子级联激光的大区域SF6泄露实时检测

采用量子级联激光器的可调谐半导体激光吸收光谱技术及可移动开放式光路系统在线检测泄露区域的SF_6气体.光路系统位于高压组合电器间隔周围,与传感系统通过非接触组合.中红外激光器的工作温度在10℃且注入电流为680 mA时发射频率范围可覆盖SF_6气体的选择波长.通过对大区域实验舱的内环境进行多次抽取分离,得到二次谐波吸收的精确背景吸收,利用10.55μm的可调谐激光传感系统对泄露扩散平衡后的SF_6气体进行测量,扣减背景吸收后得到泄露SF_6气体的二次谐波吸收光谱.研究结果表明:14.3 m的开放式光路下,气相色谱-热导率检测器溯源校准数据与可调谐半导体激光吸收光谱技术检测一致性良好,最大偏差为2.26%,二次谐波最大信号幅值与测量浓度具有较高拟合度,拟合系数为0.998,SF_6体积浓度的检测下限为1.8×10~(-6).该研究可为SF_6气体泄露提供一种全新的检测方法,从而实现高压组合电器大区域环境下SF_6气体实时在线监测.     

共振简并四波混频光学相位共轭的研究

本文考虑了非线性极化强度对cos(k·r)的依赖关系,对共振增强简并四波混频的半经典处理提出了修正,得到相位共轭反射率满足的Riccatti方程.使用可调谐连续波CO_2激光器和SF_6气体作非线性介质作了实验研究.获得了(0.2～0.8)×10~(-4)的反射率.     

腔外多普勒频率调制激光稳频方法的研究

利用腔外气体吸收池内的SF_6分子饱和吸收线作为参考频率,并通过振动腔外反射镜使进入吸收池的激光的频率受到多普勒调制,实现了对CO_2激光10P(16)和10P(18)支线频率的闭环锁定,最大频率漂移约为7kHz.该法得到的稳频激光输出不仅无寄生频率调制和幅度调制,并且可将激光频率锁定在独立的分子吸收线中心.     

罗丹明6G的三维荧光和共振散射光谱

研究了罗丹明6G(R6G)的荧光光谱、共振散射光谱和吸收光谱,讨论了共振光散射与共振荧光的区别与联系。在罗丹明6G水溶液的三维荧光等高线光谱中,瑞利散射线与荧光等高线有部分相交。共振散射峰(544nm)介于荧光激发峰(530nm)和发射峰(552nm)之间。由光偏振实验,测得R6G共振散射光谱544nm处的偏振度P为0.0105。上述实验结果证明,R6G的共振散射峰主要是共振荧光。共振光散射信号随pH值增大而增强的机理是R6G酸碱平衡移动导致荧光型体的形成。由于自吸收的影响,荧光强度、共振散射光强度与R6G浓度之间不是严格的线性关系。     

α-P/GaAs(100)界面的光电子能谱研究

本文采用X射线光电子能谱、紫外光电子能谱和低能电子衍射对室温下P在GaAs(100)表面上的生长进行了研究。结果表明,在生长初期P是成团吸附的,随着淀积量的增加而生长成α-P薄膜,该薄膜的价带结构与等离子体淀积的α-P:H薄膜的价带结构相似。在界面处有约一单层的P与衬底表面的Ga成键。α-P覆盖层使GaAs表面势垒下降约0.2eV。 关键词：     

Radiative lifetime and oscillator strength determinations in Xe VI

Transition probabilities have been calculated for n = 0 and n = 1 transitions connecting the 5s2nl [ np (n=5-8); nf (n=4-5); nh (n=6-8); nk (n=8)] , 5s5pnl (nl=5d,6s), 5p3 and 5s2nl [ (ns (n=6-8); nd (n=5-8); ng (n=5-6); ni (n=7-8)] and 5s5p2 configurations of Xe VI. Core-polarization effects have been included in the framework of a Hartree-Fock approach. The accuracy of the present set of results has been assessed through comparisons with radiative lifetime measurements. Good agreement has been observed between theory and experiment.     

High-Resolution Measurements of HBr Transitions in the First Overtone Band Using Tunable Diode Lasers

High-resolution absorption lineshapes of the R(7) and P(2) transitions in the first overtone (v = 0-2) band of H(79)Br have been recorded at room temperature using a pair of distributed feedback diode lasers operating near 1.95 and 2.00 μm, respectively. Spectral line intensities and self-broadening coefficients were determined by fitting the measured spectra (for various pressures P = 10-100 Torr) with Voigt profiles and compared with values in the literature. Measured line intensities for the P(2) and R(7) transitions are approximately 11 and 16% higher than those listed in the HITRAN database, respectively. The measured self-broadening coefficient of the P(2) transition is approximately 14% lower than the value listed in HITRAN. Measurements of the P(2) lineshapes at low pressure (100 mTorr) were modeled with eight-line Gaussian profiles based on ground state (v = 0) hyperfine constants to include the effects of nuclear electric quadrupole interactions. Copyright 2000 Academic Press.     

Spectroscopic Studies of Oxygen-Bridged Copper (II) Cluster Complexes; (I) Dimeric Copper (II) Complexes of 2-Aminopyridine and Pentane-2,4-Dionate

X-band E.P.R and also the far infrared spectra of alkoxy-bridged dimeric copper (11) complexes of 2-aminopyridime and pentane-2, 4-dionate were recorded and the two sets of data thus obtained have been correlated.

The E.P.R spectra were analysed in terms of an axial (S=1) spin Hamiltonian. Zero-field splitting parameter (D) was calculated for each complex and an attempt was made in order to correlate the obtained values with the magnetic coupling constants (J) of some compounds with analogous structures.

An assignment has been made of the bands related to the central Cu202 bridging skeleton and the observed similarity in the frequency magnitude of a strongly CuOCu angle dependent mode has been proposed to arise from nearly equal angles in the seri of complexes.

The correlative results indicated in the above have therefore enabled the identification of a ferromagnetic exchange mechanism in the seri of complexes with J values larger than 242.5 cm-1.     

Monte Carlo simulations of primitive models for ionic systems using the Wolf method

Thermodynamic and structural properties of primitive models for electrolyte solutions and molten salts were studied using NVT and NPT Monte Carlo simulations. The Coulombic interactions were simulated using the Wolf method [D. Wolf, Phys. Rev. Lett. 68, 3315 (1992); D. Wolf, P. Keblinnski, S. R. Phillpot, and J. Eggebrecht, J. Chem. Phys. 110, 8254 (1999)]. Results for 1?:?1 and 2?:?1 charge ratio electroneutral systems are presented, using the restricted and non-restricted primitive models, as well as a soft PM pair potential for a monovalent salt [J.-P. Hansen and I. R. McDonald, Phys. Rev. A 11, 2111 (1975)] that has also been used to model 2?:?12 and 1?:?20 asymmetric colloidal systems, with size ratios 1?:?10 and 2?:?15, respectively [B. Hribar, Y. V. Kalyuzhnyi, and V. Vlachy, Molec. Phys. 87, 1317 (1996)]. We present the predictions obtained for these systems using the Wolf method. Our results are in very good agreement with simulation data obtained with the Ewald sum method as well as with integral-equation theories results. We discuss the relevance of the Wolf method in the context of variable-ranged potentials in molecular thermodynamic theories for complex fluids.     

Force chain splitting in granular materials: A mechanism for large-scale pseudo-elastic behaviour

We investigate both numerically and analytically the effect of strong disorder on the large-scale properties of the hyperbolic equations for stresses proposed in J.-P. Bouchaud, M.E. Cates, P. Claudin, J. Phys. I 5, 639 (1995), and J.P. Wittmer, P. Claudin, M.E. Cates, J.-P. Bouchaud, Nature 382, 336 (1996); J.P. Wittmer, P. Claudin, M.E. Cates, J. Phys. I 7, 39 (1997). The physical mechanism that we model is the local splitting of the force chains (the characteristics of the hyperbolic equation) by packing defects. In analogy with the theory of light diffusion in a turbid medium, we propose a Boltzmann-like equation to describe these processes. We show that, for isotropic packings, the resulting large-scale effective equations for the stresses have exactly the same structure as those of an elastic body, despite the fact that no displacement field needs to be introduced at all. Correspondingly, the response function evolves from a two-peak structure at short scales to a broad hump at large scales. We find, however, that the Poisson ratio is anomalously large and incompatible with classical elasticity theory that requires the reference state to be thermodynamically stable. Received 13 November 2000 and Received in final form 3 January 2001     

Spectral investigation of nematic liquid crystals with high optical anisotropy at THz frequency range

Liquid crystals (LCs) with high optical anisotropy are very desirable for different applications in devices, such as filters, phase shifters, or phase gratings [T. Göbel, P. Meissner, A. Gaebler, M. Koeberle, S. Mueller, and R. Jakoby, Dual-Frequency Switching Liquid Crystal Based Tunable THz Filter, CLEO, Baltimore, MD, 2009; C.-Y. Chen, T.-R. Tsai, C.-L. Pan, and R.-P. Pan, Room temperature terahertz phase shifter based on magnetically controlled birefringence in liquid crystals, Appl. Phys. Lett. 83 (2003), pp. 4497–4499; and C.-J. Lin, C.-H. Lin, Y.-T. Li, R.-P. Pan, and C.-L. Pan, Electrically controlled liquid crystal phase grating for terahertz waves, IEEE Photon. Technol. Lett. 21 (2009), pp. 730–732]. We present spectral studies of LCs with large optical anisotropy in the range from 0.3 to 3?THz. Nematic LC mixtures which have Δn?>?0.30 for visible frequency range, i.e., 1825 (Δn?=?0.42 at 633?nm) were measured. Properties of LC materials like birefringence, absorption coefficients, and refractive indices for ordinary and extraordinary polarization in THz range were obtained. Orientation of LC was done by a high electric field. Measurements were performed using a TDS spectra 3000 spectrometer.     

Fermions tunneling from apparent horizon of FRW universe

In the paper [R.-G. Cai, L.-M. Cao, Y.-P. Hu, arXiv: 0809.1554], the scalar particles' Hawking radiation from the apparent horizon of Friedmann–Robertson–Walker (FRW) universe was investigated by using the tunneling formalism. They obtained the Hawking temperature associated with the apparent horizon, which was extensively applied in investigating the relationship between the first law of thermodynamics and Friedmann equations. In this Letter, we calculate fermions' Hawking radiation from the apparent horizon of FRW universe via tunneling formalism. Applying WKB approximation to the general covariant Dirac equation in FRW spacetime background, the radiation spectrum and Hawking temperature of apparent horizon are correctly recovered, which supports the arguments presented in the paper [R.-G. Cai, L.-M. Cao, Y.-P. Hu, arXiv: 0809.1554].     

The N.M.R. spectrum of coumarine partially oriented in a nematic mesophase

The proton magnetic resonance spectrum of coumarine oriented in a nematic mesophase has been recorded and analysed in terms of the proton-proton dipolar coupling constants and anisotropic chemical shifts. An analysis of the isotropic P.M.R. spectrum is also reported. The N.M.R. spectral parameters indicate that the molecule is planar and has a structure of the naphthalene type, with no apparent distortions in the aromatic ring. The internuclear proton distances derived from the N.M.R. experiment are reported, together with the orientation parameters.