共查询到20条相似文献,搜索用时 13 毫秒
1.
E. Parloo P. Verboven P. Guillaume M. Van Overmeire 《Journal of sound and vibration》2003,262(1):161-173
In-operation modal analysis has become a valid alternative for structures where a classic forced-vibration test would be difficult if not impossible to conduct. The modelling of output-only data obtained from naturally excited structures is particularly interesting because the test structure remains in its normal in-operation condition during the test. One of the drawbacks of in-operation analysis is that part of the modal parameters can no longer be estimated. Consequently, the applicability of in-operation modal models remains somewhat restricted. For some in-operation applications, interest lies in the identification of the forces that gave rise to the measured response signals. In order to solve this ill-conditioned problem, a complete modal model of the structure is required. Recently, a sensitivity-based method was proposed for the normalization of operational mode shape estimates on the basis of in-operation modal models only. This method allows the reconstruction of complete modal models from output-only data. In this paper, the possibility of using such re-completed in-operation modal models for the identification of localized forces is explored. 相似文献
2.
MV Muftakhov YV Vasil'ev VA Mazunov 《Rapid communications in mass spectrometry : RCM》1999,13(12):1104-1108
Appearance energies of [M-H](-) ions from carbonyl compounds R-CO-R' (R,R' = H, CH(3), NH(2), OH) have been measured by means of negative ion mass spectrometry in resonant electron capture mode. Values of electron affinity of the corresponding radicals, CH(2)&dbond;C(X)O, NH&dbond;C(X)O and O&dbond;C(X)O, have been determined. Copyright 1999 John Wiley & Sons, Ltd. 相似文献
3.
针对混沌系统参数辨识问题, 在基本群智能算法粒子群优化算法的基础上, 提出量子粒子群算法, 测试函数证明了算法具有良好的全局优化能力. 进而将其应用于混沌系统参数辨识问题, 将参数辨识问题转化为多维函数空间上的优化问题. 通过对平衡板热对流典型混沌系统Lorenz系统进行研究, 并与基本算法和遗传算法比较. 仿真实验证明, 算法的有效性, 对混沌理论的发展有着非常重要的意义.
关键词:
量子粒子群算法
混沌系统
系统辨识 相似文献
4.
H. Ohoyama Y. Nagamachi T. Kasai 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,38(1):231-236
A pure and high intense pulsed supersonic CH (X2Π ) radical beam
source was developed via the C(1D) + H2 reaction. An electrostatic
hexapole field was used to state-select CH radicals. The focusing curves for
the single rotational states of CH were measured for the first time by a
saturated laser-induced fluorescence (SLIF) spectroscopy for the R-branch in
A2Δ3/2 ← X2Π 1/2 transition. The
focusing curves were simulated by the classical trajectory simulation based
on a Stark energy analysis of the rotational energy levels, including
spin-orbit and Λ-doubling coupling effects. In addition,
orientational distribution functions were calculated for the selectable
states. 相似文献
5.
M. Balarin 《Solid State Communications》1980,34(6):419-422
Correlations are deduced for the asymmetry and the halfwidth of a signal peak which correspond to a discrete level using different “isothermal” trap spectroscopy techniques. Using only the temperature of the scan peak maximum and the halfwidth δ = T2 ? T1 the activation energy can then be determined: , where TK(=4500?6000 KeV-1) is given numerically for certain frequently applied trap spectroscopy techniques. TK is the result of a complete mathematical treatment of the kinetic equation. 相似文献
6.
A new mechanism for pumping of an X-ray laser by an optical laser is suggested. The inverse population between the inner levels of atoms is attained by means of the use of fast laser plasma electrons. 相似文献
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8.
Dücker EB Kuhn LT Münnemann K Griesinger C 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2012,214(1):159-165
The Non-Hydrogenative Parahydrogen-Induced Polarization (NH-PHIP) technique, which is referred to as Signal Amplification by Reversible Exchange (SABRE), has been reported to be applicable to various substrates and catalysts. For more detailed studies, pyridine was mainly examined in the past. Here, we examined several pyrazole derivatives towards their amenability to this method using Crabtree's Catalyst, which is the polarization transfer catalyst that is best documented. Additionally, the dependence of the signal enhancement on the field strength, at which the polarization step takes place, was examined for pyridine and four different pyrazoles. To achieve this, the polarization step was performed at numerous previously determined magnetic fields in the stray field of the NMR spectrometer. The substrate dependence of the field dependence proved to be relatively small for the different pyrazoles and a strong correlation to the field dependence for pyridine was observed. Reducing the number of spins in the catalyst by deuteration leads to increased enhancement. This indicates that more work has to be invested in order to be able to reproduce the SABRE field dependence by simulations. 相似文献
9.
K. A. McLauchlan 《Applied magnetic resonance》1996,11(3-4):357-373
The various Electron Spin Resonance methods that have been used for studying transient free radicals are described, and their limitations and advantages discussed. Continuous wave and Fourier Transform time-resolved methods are compared and shown to be complementary in studies of radicals produced using flash photolysis. The role of Chemically Induced Dynamic, Electron Polarization (CIDEP) in determining reaction pathways and in linking the photochemistry and photophysics of molecules is described as is the role played by Reaction Yield Detected Magnetic Resonance (RYDMR) and magnetic field effect (MFE or MARY) studies in understanding the reactions of radicals. 相似文献
10.
Ultrashort pulsed laser ablation in vacuum of different targets was performed in order to investigate the possibility of producing nanoparticles with controlled size and shape. A systematic morphology characterization of deposited products was performed for nickel and silicon as a function of laser pulse intensity and wavelength, at a fixed pulse repetition rate. The nanoparticles were investigated by atomic force microscopy, and clear trends for their size and shape anisotropy were evidenced. The best conditions to obtain nanosized particles of oblate ellipsoidal shape, with the minor axis below 10 nm, were determined in the case of nickel targets. Our results show that ultrashort pulse laser deposition can be considered as an interesting technique for the tailoring of nanogranular films with the desired particles dimension and shape, according to the peculiar properties required in specific applications. Moreover, the preliminary features are very promising from the point of view of the production of magnetoresistive films with specific anisotropy. 相似文献
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Light-sheet generator systems using a sweeping, focused laser beam and spherocylindrical optical components are described and their respective performances discussed. They allow the visualization of supersonic air flows by means of light scattering. Tomographic recordings give a three-dimensional reconstruction of the flow (especially the stationary structures) and can be realized in real-time. 相似文献
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14.
We report on a new generation of muon lifetime experiments at PSI to measure the nuclear muon capture rate in hydrogen and deuterium with ≤1% accuracy. The goals are to determine in μp capture the induced pseudoscalar coupling g P predicted in HBchPT, and in μd capture the axial two-body current term L1A described by modern EFT’s. For the μp experiment a hydrogen TPC was developed as active muon stop detector, surrounded by cylindrical wire chambers and a plastic hodoscope as electron detector. Ultra-high purity of the hydrogen isotope $^1H_1$ at levels below 10???8 was achieved with a specially developed gas circulation and purification system, and with a novel isotope separation column. About 2 ·1010 events were collected which are now in final analysis. Data from the first production run result in g P = 7.3 ± 1.1 in good agreement with theory. The μd experiment is in development. It requires measurements in ultra-pure, cold deuterium gas at ~30K. For this we are constructing a new Cryo-TPC. 相似文献
15.
《Physics letters. A》2004,331(5):316-324
An on-line procedure for recovering the unknown parameters set of the Duffing's oscillator by means of a reduced order proportional integral observer is presented in this Letter. First, it is shown that the oscillator has the properties of being algebraically observable and algebraically identifiable with respect to a well-chosen output (which turns out to be the oscillator's position). Therefore, an extended differential parametrization of the output and its time derivatives can be obtained. This extended differential parametrization has the necessary information to estimate the output time derivatives and to recover the unknown parameters. The numerical implementation of this method is easily accomplished in a digital computer. 相似文献
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在电流丝模型对HL-2A装置等离子体边界重建取得满意结果[3]、[5]的基础上,本文用有限电流元模型对HL-2A等离子体边界进行了重建研究。计算和实验结果表明,在通常情况下,有限电流元模型比固定电流丝模型的重建误差稍小,前者误差小于3mm,后者误差小于6mm。当部分有限电流元分布在等离子体边界之外时,用有限电流元模型仍然可以成功重建边界。有限电流元的位置在一定范围内变化时,重建的误差都很小。用普通奔腾4 2.4GHz PC机计算一组等离子体放电边界的时间不超过1ms。有限电流元法能准确而快速地识别等离子体的偏滤器位形,这对于HL-2A装置的实时位形控制是基本和重要的。 相似文献
18.
R. Bowman N. Muller X. Zambrana-Puyalto O. Jedrkiewicz P. Di Trapani M. J. Padgett 《The European physical journal. Special topics》2011,199(1):159-166
We use a Spatial Light Modulator (SLM) to produce arrays of Bessel beams by using multiple axicon phase-masks on the SLM.
This approach utilises the whole of the SLM, rather than just a thin annular region (which is the case if the SLM is in the
far-field of the generated Bessel beams). Using the whole SLM rather than just an annular region means that the required intensity
on the SLM is an order of magnitude lower for a given power in the Bessel beams. Spreading the power over the whole SLM is
important for high-power applications such as laser micromachining. We allow the axicons to overlap and interfere in the hologram,
so the axial length of the Bessel beam core is maintained as we add more beams to the array. 相似文献
19.
根据Shafranov电流密度矩理论,给出了用可移动电流丝方法重建HL-2A装置等离子体边界的具体计算方法,研究了用可移动电流丝方法(VCF法)重建边界的可行性.VCF法与固定电流丝方法(FCF法)和有限电流元法(FCE法)相比,最大的优点就是用1—3个可移动电流丝就可以准确地重建位置和小半径快速变化的等离子体位形,这正好弥补了FCF法的不足.将可移动电流丝方法和FCF法相结合,可以实现全程等离子体放电的边界实时显示和等离子体的位形控制.
关键词:
可移动电流丝方法
边界识别 相似文献