饱和砂岩的滞弹性弛豫衰减特征及微观机理的探索

应用Metravib热机械分析仪,以饱和岩石进行正弦波加载的方式, 分别对三种不同孔隙度的泵油饱和彭山砂岩、泵油和甘油饱和自贡长石砂岩进行了衰减实验研究,得到衰减的热弛豫规律.据此规律求得它们的激活能和原子振动频率, 其激活能和原子的振动频率比间隙原子的激活能和振动的频率低, 此现象用饱和砂岩中产生的缺陷原子簇的整体振动比单个或孤立的原子的振动频率低做出了解释. 在饱和岩石的晶粒间界缺陷处参与扩散的是固体原子、液体及气体原子. 并得出随孔隙度和黏滞系数增大,衰减强度和激活能增大,原子的振动频率增高,弛豫时间减小的结论. 在正弦波应力作用下,由多种矿物晶体胶结而成的饱和砂岩是一种多晶、多相的固体, 由于内部结构复杂、缺陷广布,产生弛豫衰减是普遍现象.砂岩中存在点缺陷、位错、 晶界及孪晶界面等许多缺陷及缺陷间的相互作用都可以产生弛豫型衰减峰. 用饱和砂岩中特有的饱和液体及砂岩内部结构的复杂性解释了饱和砂岩的衰减机理, 很自然地将其宏观衰减特征与微观结构紧密连在一起.饱和砂岩中的各种缺陷、 相界等会导致多重弛豫,使它们的弛豫衰减峰变宽,分布参数增大.这项研究既具有理论意义,也具有实用价值.     

黏弹介质包裹的充液管道中低频轴对称波传播特性

研究埋地充液管道中低频轴对称波传播特性。将土壤考虑为黏弹介质,结合Kennard薄壳方程和Kelvin-Voigt线性黏弹性模型,引入土壤载荷矩阵,推导出土-管滑移情形下流体主导波和管壁压缩波的相速度表达式。通过数值模拟计算得到流体主导波和管壁压缩波的频散和衰减曲线并进行可靠性验证,分析两种波引起的管壁径向位移之比,讨论厚径比和品质因子对流体主导波传播的影响。结果表明,黏弹介质对流体主导波和管壁压缩波的相速度影响较小,但对衰减影响较大;流体主导波对管壁径向位移有较大的影响,是泄露噪声传播的主要载体;厚径比越大,流体主导波的相速度越大,衰减越小;而品质因子越大,流体主导波的频散和衰减都越小。研究结果可为埋地充液管道的泄漏检测提供一定的理论参考。     

有效测量套管井泄漏Lamb波衰减的实验研究

低密度水泥在油气井中的广泛应用使得常规的声阻抗类测井方法难以准确、有效地评价固井质量,而声波倾斜入射在套管中激发的弯曲型Lamb波对水泥的性质及胶结情况具有很高的分辨能力,能够很好地解决低密度水泥的固井质量评价问题。弯曲型Lamb波对套管后介质声学信息的响应反映在声波衰减中,因此该文通过实验研究了激发弯曲型Lamb波的有效方式,分析了声波入射和接收角度对Lamb波衰减的影响。实验结果表明,入射和接收角度在一定范围内变化时,虽然激发出的Lamb波模式均为弯曲型Lamb波,但在同一套管模型下测量的声波衰减值会有差异,选择激发弯曲型Lamb波的最有效方式,计算得到的Lamb波衰减对套管后介质的灵敏度才会最高。     

金属板中Lamb波波速与应力关系的实验研究

本文给出了金属板中Lamb波波速对同向应力变化率测量的装置,探讨分析了测量原理及误差,并对Lamb波的波速与应力关系进行了实验研究。结果表明Lamb波的波速对应力有较好的线性关系,Lamb波相速度对应力的变化率的实验值与理论值符合很好。     

多肽和蛋白质NMR预饱和实验中饱和转移效应的研究

通过改变预饱和照射时间研究了一些多肽和蛋白质分子在水溶液中的饱和转移效应.定量分析了在照射60s之后大分子中绝大多数酰胺质子仍不受影响的原因.结果表明:具有稳定的三维溶液结构的蛋白质(如溶菌酶)中,活泼氢的信号基本上不受饱和转移影响;对于溶液结构比较稳定的多肽和蛋白质(如胰岛素),只有少部分酰胺质子信号强度受到影响;小分子六肽因为溶液中不存在稳定的构象,饱和转移效应十分显著.因此对于溶液中多肽与蛋白质构象的NMR研究,预饱和仍不失为一种简便而有效的溶剂峰压制技术.     

辐射背景对岩石受力热红外光谱变化影响的实验研究

研究表明,岩石在加载过程中表面的红外辐射随应力发展而变化,而辐射信息的有效提取与辐射背景存在密切关系。通过理论分析不同实验环境对岩石受力热红外光谱变化影响,开展了花岗岩在室内外环境下的受力热红外光谱观测实验,分析了不同辐射背景下岩石红外辐射与应力的相关性以及由应力引发的辐射变化信息的强弱差异,并对两种环境下岩石应力热红外探测的优势波段进行了对比分析。结果表明,辐射背景对岩石受力热红外光谱探测结果有重要影响,室外环境因背景辐射较弱,相同应力作用下的红外辐射变化更加显著,与应力之间的相关程度更高,优势波段区间更宽,更加有利于岩石应力的热红外探测。8.0~11.8 μm波段是利用热红外遥感监测地表花岗岩应力变化的优势波段。     

新型激光玻璃饱和通量的实验研究

 以Frantz-Nodvik公式为基础,用平均通量法,通过测量以一种新型激光玻璃为增益介质的放大器的小信号增益及其输入、输出通量,得出了该激光玻璃在短脉冲下的饱和通量值。同时通过对测试数据的分析,得出了输出通量与饱和通量的经验关系式。     

新型激光玻璃饱和通量的实验研究

以Frantz-Nodvik公式为基础,用平均通量法,通过测量以一种新型激光玻璃为增益介质的放大器的小信号增益及其输入、输出通量,得出了该激光玻璃在短脉冲下的饱和通量值。同时通过对测试数据的分析,得出了输出通量与饱和通量的经验关系式。     

原子饱和吸收谱谐波稳频短期稳定度研究

介绍了利用腔外饱和吸收谱的三次谐波和五次谐波稳频方法对半导体激光器进行稳频的原理,分析了使用这两种稳频方法对半导体激光器进行稳频时所得到的激光频率短期稳定度的理论估算方法,提出了通过选取最佳调制深度来优化短期稳定度的方法和原理,并在理论上比较了两种稳频方法得到的短期稳定度的差异。然后讨论了半导体激光稳频电路系统的设计,并利用该电路系统,分别用三次谐波和五次谐波稳频的方法将半导体激光器的频率锁定在的^87Rb饱和吸收的F=2→F′=3,1线上,并使用我们提出的短期稳定度优化方案进行稳定度优化,通过对误差信号的分析,估算出的频率稳定度达到10^-12的量级,使用采集到的误差信号在实验上比较了两种稳频方法所得的稳定度的,其结果和理论基本吻合。     

Transmission Properties of Closed Trapezoidal-Groove Guide for Millimeter Waves

The transmission characteristics of the mode TE₁₁ for a new type of closed trapezoidal-groove guide with arbitrary inclined angle are analysed in detail with the mode-matching method in this paper. The calculated results are in good agreement with the experimental values in the published reference. The dispersion of the closed trapezoidal-groove guide is very low. The relationships of the cut-off wavelength and the attenuation constant with the structural sizes of the closed trapezoidal-groove waveguide are also obtained. The given results have very important value in study, design, manufacture and application for closed trapezoidal-groove waveguide.     

Experimental studies on perturbed acoustic resonant spectroscopy by a small rock sample in a cylindrical cavity

A measurement system for acoustic resonant spectroscopy (ARS) is established, and the effects of resonant cavity geometry, inner perturbation samples and environmental temperature on the ARS are investigated. The ARSs of the small samples with various sizes and acoustic properties are measured. The results show that at the normal pressure, the resonant frequency decreases gradually with the increase of liquid temperature in the cylindrical cavity, while the resonant amplitude increases. At certain pressure and temperature, both the resonant frequency and the amplitude decrease greatly when there exist air bubbles inside the cavity fluid. The ARS is apparently affected by the sample porosity and the sample location in the resonant cavity. At the middle of the cavity, the resonant frequencies reach their maximum values for all of the measurement samples. The resonant frequencies of the porous rock samples are smaller than those of the compacted samples if other acoustic parameters are the same. As the sample is moved from the top to the middle of the cavity along its axis, the resonant amplitude increases gradually for the compacted rocks while decreases for the unconsolidated rocks. Furthermore, the resonant amplitude increases firstly and then decreases if the porosity of the rock sample is relatively small. In addition, through the comparisons between the experimental and theoretical results, it is found that the effects of the acoustic parameters and sizes of the samples and the size of the cylindrical cavity on the laboratory results agree well with the theoretical ones qualitatively. These results may provide basic reference for the experiment study of rock acoustic properties in a low frequency using ARS.     

泡沫红外消光影响因素的实验研究

通过红外光谱实验和红外热成像实验,研究了影响泡沫红外消光的因素,结果表明:泡沫溶液的红外光谱特征决定红外光谱吸收峰位,且溶质浓度越高,吸收越强;泡沫结构是造成光线强烈衰减的重要原因,透射光强随光线穿过泡沫液膜界面的次数成指数衰减,泡沫直径越小,达到相同遮蔽效果的泡沫溶液的用量就越少;当泡沫直径远大于入射光线波长时,透射比随光束大小变化不大;泡沫溶液升温可在一定程度上增强泡沫的红外吸收强度.各因素影响程度从大到小的次序为:泡沫结构,红外光谱特征,内充气体折射率,泡沫直径,温度.     

Experimental research on performances of the imaging plates applied in gamma-ray imaging

Experimental studies on the basic characteristics of IPs applied in T-ray imaging are carried out by utilizing isotopic y-ray sources. The 1.25 MeV T-ray sensitivity of the BAS-MS and BAS-TR imaging plates and their enhanced sensitivity by covering appropriate Compton conversion foils are measured based on the studies of the image intensity linear calibration, time attenuation laws and the influence of scanning parameter settings. The energy-dependent T-ray sensitivity of the IPs is also obtained by the studies of the measured sensitivity and the Monte Carlo simulated energy deposition in the IPs＇ sensitive layer. Furthermore, a method of a sandwich detection structure as well as its primary experimental validations are presented in order to increase the gamma-to-neutron ratio in a y/n mixed radiation field.     

Extended frequency range measurements for determining the Kneser-type acoustic relaxation time

In the present paper, the authors discuss studies carried out for many years dealing particularly with two compounds: benzene and carbon disulphide and compare them with the results obtained by numerous acoustics researchers. These compounds are typical liquids in which acoustic Kneser-type relaxation occurs, caused by an irreversible vibrational and translational (VT) transition. Since magnitudes describing the relaxation process were diverse in many papers, we have undertaken an attempt to clarify these differences and to indicate how to avoid errors resulting from instrumental imperfections and the disregard of the considerable measurement errors when investigating velocity dispersion in the hypersonic (GHz) range. The results of these researches changed the interpretation of previous papers.     

基于波导相位调制器的光谱色散平滑技术实验研究

利用波导相位调制器产生的正弦调频脉冲进行了光谱色散平滑技术实验研究.结果表明该铌酸锂波导相位调制器可以容易地将DFB振荡器产生的单纵模信号展宽到0.1—1.5 nm,远场分析表明焦斑扫动规律与理论计算一致,近场分析表明SSD对近场百微米尺度的调制有显著改善.本研究为高功率激光装置束匀滑方案的优化提供了参考. 关键词： 远场 近场 光谱色散平滑 惯性约束聚变     

分立式色散补偿拉曼放大器增益特性及非线性现象研究

分立式色散补偿拉曼放大器具有兼顾色散补偿和信号放大的特点，在通信系统中展现出广阔的应用前景.对反向抽运的C波段色散补偿分立式拉曼放大器的增益谱形状，增益饱和及受激布里渊散射等特性进行了较为详细的实验研究. 关键词： 分立式色散补偿拉曼放大器 增益饱和 受激布里渊散射 斯托克斯波     

钻具遇卡声波检测理论与实验研究*

石油钻探过程中,钻具经常发生陷入泥沙中不能自由活动进而卡在井下的事故。本文提出使用单发双收声系来检测钻具遇卡的方法,首先使用有限差分模拟了钻具外为自由流体和泥沙两种介质时的钻铤波响应,通过对比远近接收器的钻铤波衰减,发现泥沙卡钻情况下的钻铤波衰减要明显大于自由钻具情况。随后建立了实验模型对理论结果进行了验证。理论模拟与实验结果均表明声波方法可用以检测钻具遇卡事故,从而确定卡钻的深度位置,为解卡钻作业提供解释依据。     

基于最小二乘法的声速测定实验数据处理及分析

用振幅极大值法比振幅极小值法测声速的误差小和声波在传播过程中声压按指数函数关系衰减。