Compaction of Sand on a Vertically Vibrating Table

2009 ◽  
pp. 156-156-15 ◽  
Author(s):  
R Dobry ◽  
RV Whitman
Keyword(s):  
Vibrating Table

scholarly journals Pulse-Width Multiplexing ϕ-OTDR for Nuisance-Alarm Rate Reduction

Sensors ◽  
2018 ◽  
Vol 18 (10) ◽  
pp. 3509 ◽  
Author(s):  
Xiang Zhong ◽  
Xicheng Gao ◽  
Huaxia Deng ◽  
Shisong Zhao ◽  
Mengchao Ma ◽  
...  
Keyword(s):  
Pulse Width ◽  
Signal To Noise Ratio ◽  
Fusion Algorithm ◽  
Multisensor Data Fusion ◽  
Optical Time Domain Reflectometer ◽  
Light Pulses ◽  
Phase Sensitive ◽  
Evidential Theory ◽  
Vibrating Table ◽  
Optical Time

A pulse-width multiplexing method for reducing the nuisance-alarm rate of a phase-sensitive optical time-domain reflectometer ( ϕ -OTDR) is described. In this method, light pulses of different pulse-widths are injected into the sensing fiber; the data acquired at different pulse-widths are regarded as the outputs of different sensors; and these data are then processed by a multisensor data fusion algorithm. In laboratory tests with a sensing fiber on a vibrating table, the effects of pulse-width on the signal-to-noise ratio (SNR) of the ϕ -OTDR data are observed. Furthermore, by utilizing the SNR as the feature in a feature-layer algorithm based on Dempster–Shafer evidential theory, a four-pulse-width multiplexing ϕ -OTDR system is constructed, and the nuisance-alarm rate is reduced by about 70%. These experimental results show that the proposed method has great potential for perimeter protection, since the nuisance-alarm rate is significantly reduced by using a simple configuration.

Analytical Dynamics of a Ball Bouncing on a Vibrating Table

2012 ◽  
Author(s):  
Yu Guo ◽  
Albert C. J. Luo
Keyword(s):  
Dynamical Systems ◽  
Numerical Simulations ◽  
Analytical Dynamics ◽  
Periodic Motions ◽  
Chaotic Motions ◽  
Theory Of Flow ◽  
Mapping Structures ◽  
Ball Bouncing ◽  
Vibrating Table

In this paper, the theory of flow switchability for discontinuous dynamical systems is applied. Domains and boundaries for such a discontinuous problem are defined and analytical conditions for motion switching are developed. The conditions explain the important role of switching phase on the motion switchability in such a system. To describe different motions, the generic mappings and mapping structures are introduced. Bifurcation scenarios for periodic and chaotic motions are presented for different motions and switchability. Numerical simulations are provided for periodic motions with impacts only and with impact chatter to stick in the system.

Research on Multi-Excitation Source United Controlling Test Method Based on Distributed Actuation

2011 ◽  
Vol 291-294 ◽  
pp. 2168-2174
Author(s):  
Jun Yao ◽  
Yan Fei Wu ◽  
Ming Ge Xu
Keyword(s):  
High Speed ◽  
Engineering Application ◽  
Piezoelectric Element ◽  
Test Method ◽  
Excitation Source ◽  
Vibration Test ◽  
Test Technique ◽  
Test Items ◽  
Application Potential ◽  
Vibrating Table

In view of the questions of high-speed aircraft withstanding complicated vibration environment, their vibration durability could not being plenary examined by existing vibration test technology, a vibration test technique integrating piezoelectric element, vibrating table, exciter is proposed. The vibration environment dimension of high-speed aircraft and its influence to the failures of high-speed aircraft are analysed. Based on the research on the material and actuation dimension of the piezoelectric element, the feasibility of piezoelectric element used as the distributed excitation source in vibration test is analysed. Last, a test demonstration system is constituted and a serials of test items are carried out. The rationality and the extensive engineering application potential of this technique are verified by the test results.

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