Simultaneous identification of excitation time histories and parametrized structural damages

The general track spectrum of Chinese main railway lines (ChinaRLS) and the track spectrum of American railway lines (AmericaRLS) are compared in terms of character of frequency domain, statistical property of time domain samples and dynamic performance. That the wavelength range of the ChinaRLS, which is characterized by the three levels according to the class of railway line, is less than AmericaRLS at common wave band of 1~50m is calculated. Simultaneously, the mean square values of two kinds of track spectra are provided at the detrimental wave bands of 5~10m, 10~20m, and so on. The time-histories of ChinaRLS and AmericaRLS are simulated according to the trigonometric method, and the digital statistical nature of simulated time samples is analyzed. With inputting the two kinds of time-histories into the vehicle-railway system, the comparative analysis of the two kinds of dynamic performances for ChinaRLS and AmericaRLS is done in terms of car body acceleration, rate of wheel load reduction, wheel/rail force, and the dynamic responses of track structure. The result shows that ChinaRLS can characterize the feature of the Chinese track irregularity better than AmericaRLS, the track irregularity with the ChinaRLS of 200km/h is superior to the AmericaRLS, and the track irregularity with the ChinaRLS of 160km/h corresponds to with the sixth of AmericaRLS.

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The statistical properties of raw knock signal time histories

Mechanical Systems and Signal Processing ◽

10.1016/j.ymssp.2021.107660 ◽

2021 ◽

Vol 156 ◽

pp. 107660

Author(s):

James C. Peyton Jones ◽

Saeed Shayestehmanesh

Keyword(s):

Statistical Properties ◽

Time Histories ◽

Signal Time

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A simulation study of excitation contour of a linear trap with spatial harmonics

European Journal of Mass Spectrometry ◽

10.1177/14690667211020153 ◽

2021 ◽

pp. 146906672110201

Author(s):

NV Konenkov

Keyword(s):

Ion Trap ◽

Theoretical Description ◽

Resonance Peak ◽

Linear Ion Trap ◽

Linear Trap ◽

Ion Fragmentation ◽

Excitation Time ◽

Detailed Simulation ◽

Trajectory Method ◽

Ion Cloud

The process of nonlinear resonant excitation of ion oscillations in a linear trap is studied. There is still no detailed simulation of the resonance peak in the literature. We propose to use the excitation contour to describe the collective ion resonance. The excitation contour is a resonant mass peak obtained by the trajectory method with the Gaussian distribution of the initial coordinates and velocities. The following factors are considered: excitation time, low order hexapole and octopole harmonics with amplitudes A3 and A4, the depth of the initial ion cloud position. These multipoles are used for selective ion ejection from linear ion trap. All these factors affect the ion yield and the shape of the contours. Obtained data can be useful for control of such processes as ion fragmentation, ion isolation, ion activation, and ion ejection. Simulated resonance peaks are important for the theoretical description of the ion collective nonlinear resonances.

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Simultaneous identification of contaminant sources and hydraulic conductivity field by combining geostatistics method with self-organizing maps algorithm

Journal of Contaminant Hydrology ◽

10.1016/j.jconhyd.2021.103815 ◽

2021 ◽

pp. 103815

Author(s):

Simin Jiang ◽

Jinbing Liu ◽

Xuemin Xia ◽

Zhiyuan Wang ◽

Lu Cheng ◽

...

Keyword(s):

Hydraulic Conductivity ◽

Self Organizing Maps ◽

Contaminant Sources ◽

Simultaneous Identification ◽

Self Organizing

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Space–time histories approach to fast stochastic simulation of bimolecular reactions

The Journal of Chemical Physics ◽

10.1063/5.0037266 ◽

2021 ◽

Vol 154 (16) ◽

pp. 164111

Author(s):

Thorsten Prüstel ◽

Martin Meier-Schellersheim

Keyword(s):

Stochastic Simulation ◽

Space Time ◽

Bimolecular Reactions ◽

Time Histories

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Dynamic flight load measurements with MEMS pressure sensors

CEAS Aeronautical Journal ◽

10.1007/s13272-021-00529-3 ◽

2021 ◽

Author(s):

Christian Raab ◽

Kai Rohde-Brandenburger

Keyword(s):

Pressure Distribution ◽

Pressure Sensors ◽

Flow Characteristics ◽

Flight Test ◽

Measurement Technology ◽

Test Program ◽

Aerodynamic Pressure ◽

Pressure Distributions ◽

Time Histories ◽

Mems Pressure Sensors

AbstractThe determination of structural loads plays an important role in the certification process of new aircraft. Strain gauges are usually used to measure and monitor the structural loads encountered during the flight test program. However, a time-consuming wiring and calibration process is required to determine the forces and moments from the measured strains. Sensors based on MEMS provide an alternative way to determine loads from the measured aerodynamic pressure distribution around the structural component. Flight tests were performed with a research glider aircraft to investigate the flight loads determined with the strain based and the pressure based measurement technology. A wing glove equipped with 64 MEMS pressure sensors was developed for measuring the pressure distribution around a selected wing section. The wing shear force determined with both load determination methods were compared to each other. Several flight maneuvers with varying loads were performed during the flight test program. This paper concentrates on the evaluation of dynamic flight maneuvers including Stalls and Pull-Up Push-Over maneuvers. The effects of changes in the aerodynamic flow characteristics during the maneuver could be detected directly with the pressure sensors based on MEMS. Time histories of the measured pressure distributions and the wing shear forces are presented and discussed.

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