Experimental study of underwater pulse detonation gas jets: Bubble velocity field and time–frequency characteristics of pressure field

2021 ◽  
Vol 33 (8) ◽  
pp. 083324
Author(s):  
Wei Liu ◽  
Ning Li ◽  
Xiao-long Huang ◽  
Yang Kang ◽  
Can Li ◽  
...  
Keyword(s):  
Experimental Study ◽  
Velocity Field ◽  
Pressure Field ◽  
Frequency Characteristics ◽  
Bubble Velocity ◽  
Time Frequency ◽  
Pulse Detonation ◽  
Gas Jets

Experimental study on sound radiation time‐frequency characteristics of double cylindrical shell based on EMD

2012 ◽  
Vol 29 (3) ◽  
pp. 321-337 ◽  
Author(s):  
Fang Ji ◽  
Xiongliang Yao ◽  
Aman Zhang ◽  
Xi Ye
Keyword(s):  
Experimental Study ◽  
Cylindrical Shell ◽  
Sound Radiation ◽  
Frequency Characteristics ◽  
Time Frequency ◽  
Radiation Time

EXPERIMENTAL STUDY OF DRIFT OBJECTS USING SPATIOTEMPORAL DATA UNDER COMPLEX VELOCITY FIELD

2020 ◽  
Vol 76 (2) ◽  
pp. I_313-I_318
Author(s):  
Yu CHIDA ◽  
Nobuki FUKUI ◽  
Nobuhito MORI ◽  
Tomohiro YASUDA ◽  
Takashi YAMAMOTO
Keyword(s):  
Experimental Study ◽  
Velocity Field ◽  
Spatiotemporal Data ◽  
Complex Velocity

scholarly journals Time–Frequency-Analysis-Based Blind Modulation Classification for Multiple-Antenna Systems

Sensors ◽  
2021 ◽  
Vol 21 (1) ◽  
pp. 231
Author(s):  
Weiheng Jiang ◽  
Xiaogang Wu ◽  
Yimou Wang ◽  
Bolin Chen ◽  
Wenjiang Feng ◽  
...  
Keyword(s):  
Frequency Analysis ◽  
Classification Accuracy ◽  
Communication Systems ◽  
Mimo Systems ◽  
Decision Fusion ◽  
Frequency Characteristics ◽  
Modulation Classification ◽  
Time Frequency Analysis ◽  
Time Frequency ◽  
Average Classification Accuracy

Blind modulation classification is an important step in implementing cognitive radio networks. The multiple-input multiple-output (MIMO) technique is widely used in military and civil communication systems. Due to the lack of prior information about channel parameters and the overlapping of signals in MIMO systems, the traditional likelihood-based and feature-based approaches cannot be applied in these scenarios directly. Hence, in this paper, to resolve the problem of blind modulation classification in MIMO systems, the time–frequency analysis method based on the windowed short-time Fourier transform was used to analyze the time–frequency characteristics of time-domain modulated signals. Then, the extracted time–frequency characteristics are converted into red–green–blue (RGB) spectrogram images, and the convolutional neural network based on transfer learning was applied to classify the modulation types according to the RGB spectrogram images. Finally, a decision fusion module was used to fuse the classification results of all the receiving antennas. Through simulations, we analyzed the classification performance at different signal-to-noise ratios (SNRs); the results indicate that, for the single-input single-output (SISO) network, our proposed scheme can achieve 92.37% and 99.12% average classification accuracy at SNRs of −4 and 10 dB, respectively. For the MIMO network, our scheme achieves 80.42% and 87.92% average classification accuracy at −4 and 10 dB, respectively. The proposed method greatly improves the accuracy of modulation classification in MIMO networks.

The Effect of Longitudinal Core Flow on Trailing Vortex Stability

2014 ◽  
Author(s):  
Amir Allaf-Akbari ◽  
A. Gordon L. Holloway ◽  
Joseph Hall
Keyword(s):  
Experimental Study ◽  
Velocity Field ◽  
Kinetic Energy ◽  
Vortex Core ◽  
Vortex Generator ◽  
Core Flow ◽  
Vortex Stability ◽  
Vorticity Distribution ◽  
Air Jet ◽  
Jet Velocities

The current experimental study investigates the effect of longitudinal core flow on the formation and structure of a trailing vortex. The vortex is generated using four airfoils connected to a central hub through which a jet flow is added to the vortex core. Time averaged vorticity, circumferential velocity, and turbulent kinetic energy are studied. The statistics of vortex wandering are identified and corrections applied to the vorticity distribution. The vortex generator used in this study was built on the basis of the design described by Beninati et al. [1]. It uses four NACA0012 airfoils connected to a central hub. The wings orientation can be adjusted such that each contributes to a strong trailing vortex on the center of the test section. The vortex generator also had the capability to deliver an air jet directed longitudinally through a hole in the hub at the joint of the airfoils. Tests were done without the jet and with the air jet at jet velocities of 10 and 20 m/s. Planar PIV was used to measure the velocity field in the vicinity of the vortex core. The measurements were taken at 3 chords behind the vortex generator.

Time-frequency characteristics of an elastic wave radiated by a camouflet explosion

1986 ◽  
Vol 27 (2) ◽  
pp. 285-290 ◽  
Author(s):  
A. A. Zverev ◽  
E. E. Lovetskii ◽  
V. S. Fetisov
Keyword(s):  
Elastic Wave ◽  
Frequency Characteristics ◽  
Time Frequency ◽  
Camouflet Explosion

Analysis of Time-Frequency Characteristics of PD Electromagnetic Wave Based on Electromagnetic Simulation

2018 ◽  
Author(s):  
Zijing Zeng ◽  
Jianwen Wang ◽  
Yue Hu ◽  
Zhicheng Wang ◽  
Hongyi Huang
Keyword(s):  
Electromagnetic Wave ◽  
Frequency Characteristics ◽  
Electromagnetic Simulation ◽  
Time Frequency

scholarly journals Influence of viscosity, surface tension, and inclination angle on motion of long bubbles in closed tubes

1966 ◽  
Vol 25 (4) ◽  
pp. 821-837 ◽  
Author(s):  
E. E. Zukoski
Keyword(s):  
Experimental Study ◽  
Surface Tension ◽  
Inclination Angle ◽  
Bubble Velocity ◽  
Vertical Tubes

An experimental study has been made of the motion of long bubbles in closed tubes. The influence of viscosity and surface tension on the bubble velocity is clarified. A correlation of bubble velocities in vertical tubes is suggested and is shown to be useful for the whole range of parameters investigated. In addition, the effect of tube inclination angle on bubble velocity is presented, and certain features of the flow are described qualitatively.

Sign in / Sign up

Export Citation Format

Share Document