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Understanding and control of the surface properties such as molecular orientations are of great importance in numerous applications of ionic liquids. However, there remain discrepancies among the previous experimental and theoretical studies on the surface orientation and structures of room temperature ionic liquids(RTIL) systems. In this article, the orientation of 1-butyl-3-methylimidazolium([bmin]) cation at the air/liquid interface of a characteristic RTIL, 1-butyl-3-methylimidazolium hexafluorophosphate([bmim][PF6]), was investigated by the sum frequency generation vibrational spectroscopy(SFG-VS). Detailed polarization and experimental configuration analyses of the SFG-VS spectra showed the possibility of a small spectral splitting in the CH3 symmetric stretching region, which can be further attributed to the probable existence of multiple orientations for the interfacial [bmim] cations. In addition, the(N)–CH3 vibrations were absent, ruling out the prediction by several recent molecular dynamics simulations which state that portions of the [bmim] cations orient with a standing-up(N)–CH3 group at the ionic liquid surface. Hence, new realistic theoretical models have to be developed to reflect the complex nature of the ionic liquid surface. 相似文献
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叶轮机械非定常流动研究进展 总被引:6,自引:0,他引:6
本文就叶片排进出口流场畸变型动力响应、压缩系统气动稳定性、叶轮机械非定常气动问题的数值模拟以及失速颤振轴流压气机系列转子实验等4个方面问题,从非定常气动力学角度作一概述和展望 相似文献
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具有分支电路的可控压电阻尼减振技术 总被引:15,自引:0,他引:15
对近10年来国内外关于具有分支电路的可控压电阻尼减振技术研究的进展进行了较为详细的评述和讨论.文中首先说明了具有分支电路的压电阻尼减振技术的基本原理和基本形式,然后较为全面的评述不同形式基本分支电路压电阻尼系统的基本特点和研究进展,在讨论了以基本分支电路压电阻尼系统为基础的各种具有可控特性的分支电路压电阻尼系统(包括半主动的和主动-被动杂交的分支电路压电阻尼系统)的研究与发展之后,说明了这种技术在实际工程中的应用,最后建议了今后应深入研究的问题. 相似文献
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Novel correction method for X-ray beam energy fluctuation of high energy DR system with a linear detector 总被引:1,自引:0,他引:1
A high energy digital radiography (DR) testing system has generated diverse scientific and technological interest in the field of industrial non-destructive testing. However, due to the limitations of manufacturing technology for accelerators, an energy fluctuation of the X-ray beam exists and leads to bright and dark streak artifacts in the DR image. Here we report the utilization of a new software-based method to correct the fluctuation artifacts. The correction method is performed using a high pass filtering operation to extract the high frequency information that reflects the X-ray beam energy fluctuation, and then subtracting it from the original image. Our experimental results show that this method is able to rule out the artifacts effectively and is readily implemented on a practical scanning system. 相似文献
6.
System calibration, which usually involves complicated and time-consuming procedures, is crucial for any three-dimensional (3D) shape measurement system based on vision. A novel improved method is proposed for accurate calibration of such a measurement system. The system accuracy is improved with considering the nonlinear measurement error created by the difference between the system model and real measurement environment. We use Levenberg-Marquardt optimization algorithm to compensate the error and get a good result. The improved method has a 50% improvement of re-projection accuracy compared with our previous method. The measurement accuracy is maintained well within 1.5% of the overall measurement depth range. 相似文献
7.
Vibration control of the finite L-shaped beam structures based on the active and reactive power flow
LIU ChunChuan LI FengMing TANG Liang & HUANG WenHu P.O.Box School of Astronautics Harbin Institute of Technology Harbin China P.O.Box National Laboratory of Space Intelligent Control Beijing Institute of Control Engineering Beijing 《中国科学:物理学 力学 天文学(英文版)》2011,(2)
This paper analyzes the physical meaning of the active and reactive power flow in the finite L-shaped beams and studies the active vibration control of the structures based on the active and reactive power flow.The traveling wave approach is used to calculate the structural dynamic responses.Because the error of control force is inevitable in practical applications,the effects of the error of control force on the control results are studied.The study indicates that the error of control force has pronounced ... 相似文献
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The single-molecule surface-enhanced Raman scattering(SERS) spectra of Rhodamine 6G(R6G) in an aqueous environment under non-resonance conditions are studied.Series of spectra are recorded in timemapping mode,and intensity fluctuations of SERS signals and spectral diffusion are observed.The correlations between the presence frequency of SERS spectra and number of hot spots as well as the quantity of molecules in scattering volume are examined thoroughly.The results indicate that only molecules located at hot spots produce good signal-to-noise ratio Raman spectra and the origin of fluctuating SERS signals are mainly ascribed to the movement of hot spots. 相似文献
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Review of nanofluids for heat transfer applications 总被引:2,自引:0,他引:2
Saeid Vafaei 《中国颗粒学报》2009,7(2)
Research on nanofluids has progressed rapidly since its enhanced thermal conductivity was first repotted about a decade ago,though much controversy and inconsistency have been reported,and insufficient understanding of the formulation and mechanism of nanofluids further limits their applications.This work presents a critical review of research on heat transfer applications of nanofluids with the aim of identifying the limiting factors so as to push forward their further development. 相似文献
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本文分别用流场显示和阻力测量两种实验方法,证明了平板整体摩擦阻力存在着振荡性,并得到了其振荡的一些规律和特点。另外,提出了一个与时间相关联的内层速度分布模型。并对其合理性进行了研究,从而导出一个与时间相关联的整体摩擦阻力模型。 相似文献