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61.
62.
In this work, speed of sound for n-decane, n-hexadecane and tetralin, as well as for binary mixtures involving these hydrocarbons, were determined at pressures of (0.1, 5, 10, 15, 20 and 25) MPa at temperatures of (313.15, 323.15 and 333.15) K at different compositions. Density data at atmospheric pressure for these same systems were measured experimentally at temperatures of (313.15, 323.15 and 333.15) K. From these results and thermodynamic definitions, the following properties were calculated: density at high pressures, excess molar volume and excess isentropic compressibility. Tetralin, n-decane and n-hexadecane are chemicals asymmetrical in shape, length and chemical nature that can be found in naphtha and kerosene fractions. The influence of these differences on the physical properties of these mixtures was then evaluated. Density and speed of sound data were correlated with Prigogine–Flory–Patterson (PFP) equation of state. The PFP model correlated well experimental densities for pure components but did not correlate so well the speed of sound dependency with pressure. The model calculated well excess properties, with correct signs, magnitudes, and the qualitative effect of pressure and temperature on these properties. 相似文献
63.
The excess speed of sound, excess molar volume and excess molar isentropic compressibility of 52 binary mixtures containing Ionic Liquids at T = 298.15 K were calculated using selected literature speed of sound and density data. The second components were alcohols: methanol, or ethanol, or 1-propanol, or 2-propanol, or 1-butanol or other solvents: acetone, acetonitrile, tetrahydrofuran, dichloromethane and dimethylsulfoxide. The Balankina’s relative excesses, Xbal, i.e. the ratios between excess and ideal quantities XE/Xid were also determined to reduce the structural impact of pure components to absolute excesses. Analysis of quantities determined shows some patterns for concentration dependences of large groups of mixtures; thus, the scheme for influence of anion or cation of Ionic Liquids and solvent on Balankina’s relative excesses was proposed. It seems that presented analysis provide the knowledge about absolute and relative excess quantities for other mixtures without doing the experimental work. It is also visible that analysis of excess molar quantities and Xbal parameters can support the interpretation of interactions which occur between Ionic Liquids and solvent. 相似文献
64.
Densities, speeds of sound, viscosities and refractive indices of two binary systems 1-butyl-3-methylimidazolium tetrafluoroborate [bmim][BF4] + methanol and 1-ethyl-3-methylimidazolium tetrafluoroborate [emim][BF4] + methanol, as well as of all pure components, have been measured covering the whole range of compositions at T = (278.15 to 318.15) K and p = 101 kPa. From this data, excess molar volumes, excess isentropic compressibilities, viscosity deviations and refractive index deviations were calculated and fitted to extended versions of the Redlich–Kister equation. Estimated coefficients of these equations taking into account the dependence on composition and temperature simultaneously were also presented. 相似文献
65.
提出了一种超声无触点支承方案,详细介绍了超声无触点支承原理。通过对声辐射理论的研究,获得超声无触点支承的理论依据。实验证明实现这种超声波无触点支承是可行的。根据这一理论,对三轴无触点支承结构进行了选择设计。 相似文献
66.
报道了激光诱导热光栅光谱测温技术的研究. 通过两束相干交叉的脉冲抽运光, 在NO2/N2混合气中诱导出热光栅, 一束满足布拉格散射条件的连续探测光在交叉区域激励出相干的热光栅信号, 经过空间和光谱滤波的信号光由光电倍增管探测, 并由数字示波器显示和存储. 该信号携带了丰富的流场信息, 通过频域分析, 对气体的温度进行了测量, 热光栅光谱技术测量的温度与热电偶温度符合得很好. 同时还利用热光栅光谱技术进行了气体声速的直接测量, 在一定的温度范围内, 测量结果与理论曲线基本一致, 显示了该技术具有较高的测量精度与多参数同时测量的能力. 对影响信号波形的因素进行了分析, 结果表明, 热光栅光谱测温技术在高压强环境下应用具有独特的优势, 是一种应用前景广阔的激光燃烧诊断技术. 相似文献
67.
68.
为了克服共振干涉法在液体的热力学声速和高频声速测量方面精度不高的问题, 本文建立了一种基于自发布里渊散射原理的测定液体声速的实验装置. 利用法布里-珀罗干涉仪对散射光进行扫描滤波, 数据采集卡结合光子计数器对散射光进行探测, 设计了一种散射光信息采集分析方法. 该实验方法有效的解决了传统布里渊散射方法中信号失真的问题, 显著地提升了液体声速测量精度. 对308.6–906.2 MHz内298.15 K饱和液相CCl4声速进行了测量, 测量结果与文献值具有较好一致性. 利用法布里-珀罗干涉仪周期性扫描的滤波原理, 通过在测量得到的布里渊频移上加减整数倍个自由波谱区, 得到了更大频率的波谱信息, 进而设计一种测定介质高频声速的方法. 对CCl4在5406.1–5521.0 MHz频段内的声速进行了测量. 实验结果显示, CCl4的热力学声速随频率无明显变化, 而高频声速随频率的增大呈增大趋势且远大于热力学声速, 证实CCl4具有色散现象. 相似文献
69.
In active sound control, noise shielding of a target region is achieved via additional sources (called controls) situated at the perimeter of the region. The sources protect the target region by adjusting the acoustic field near the boundary of the region. In the present paper a numerical model of active sound control based on surface potentials in 3D bounded composite regions is numerically studied. In the composite region setup, it is required that the regions be shielded from noise while allowing admissible sound that is generated in the shielded regions to be preserved. The admissible sound is usually required to propagate freely inside the protected regions or in a (selective) predetermined pattern. The adjusting approach used here does not require any knowledge of the sound sources or the properties of the propagation medium in order to obtain the controls. Moreover, the approach differs sharply from some other approaches where the detailed knowledge of the sound sources and the propagation medium is required. For the first time, numerical test cases involving both free communication and predetermined communication pattern between the regions in three dimensions are considered. In all test cases, these regions are effectively shielded from the noise while any present admissible sound is preserved. In addition, selective propagation of the admissible sound between the regions is enforced. The effect of the number of controls on their operation is also studied. Whether admissible sound is present or not, the level of noise cancellation decreases linearly as fewer controls are used. In addition to the increase in size of the interference zone, the controls become individually distinguishable. 相似文献
70.