scholarly journals TSUNAMI EARLY DETECTION:ENHANCED RESOLUTION OF HF OCEANOGRAPHIC RADAR

2011 ◽  
Vol 1 (32) ◽  
pp. 4 ◽  
Author(s):  
Yasuhiro Murata ◽  
Toshiro Nagakura ◽  
Takahiro Kokai
Keyword(s):  
Fourier Transform ◽  
Surface Current ◽  
Sea Surface ◽  
Field Of View ◽  
Wide Field ◽  
Short Time Fourier Transform ◽  
Zero Padding ◽  
Wide Field Of View ◽  
Short Time ◽  
Doppler Analysis

HF Oceanographic radar is an equipment, for instantaneously sensing velocity distribution of sea surface current. It has a wide field of view, which extends approximately ±45° in direction and beyond 50km in distance. There are high expectations that the radar observation of Tsunami will become a new road path for preventing disasters. In this paper, we describe a method to enhance the resolutions of radar in both time and current. At first, resolutions required for tsunami observation are estimated by simulating a Tokachi-oki earthquake tsunami (2003). Here it is pointed out that traditional data processing indicates inadequate resolutions for tsunami early detection. Secondly, two techniques are proposed to achieve the necessary resolutions. Short-time Fourier transform (STFT), in place of normal FFT, enhances the time resolution of Doppler analysis. Further, zero-padding technique improves the current resolution, by interpolation of data within the frequency domain. Finally, by means of simulation, it is verified that these proposed techniques give improved resolutions in both time and current.

Wide field of view, ultracompact static Fourier-transform spectrometer

1997 ◽  
Vol 68 (1) ◽  
pp. 30-33 ◽  
Author(s):  
D. Steers ◽  
B. A. Patterson ◽  
W. Sibbett ◽  
M. J. Padgett
Keyword(s):  
Fourier Transform ◽  
Field Of View ◽  
Wide Field ◽  
Fourier Transform Spectrometer ◽  
Wide Field Of View

Study of Fourier Transform Imaging Spectrometer with Wide Field of View

2016 ◽  
Vol 36 (1) ◽  
pp. 0130001
Author(s):  
张智南 Zhang Zhinan ◽  
李立波 Li Libo ◽  
胡炳樑 Hu Bingliang ◽  
冯玉涛 Feng Yutao
Keyword(s):  
Fourier Transform ◽  
Field Of View ◽  
Wide Field ◽  
Imaging Spectrometer ◽  
Wide Field Of View

STM studies of crystal growth

1991 ◽  
Vol 49 ◽  
pp. 374-375
Author(s):  
M. G. Lagally
Keyword(s):  
Crystal Growth ◽  
Molecular Beam ◽  
Chemical Vapor ◽  
Sputter Deposition ◽  
Field Of View ◽  
Scanning Tunneling ◽  
Wide Field ◽  
Tunneling Microscopy ◽  
Wide Field Of View ◽  
The One

It has been recognized since the earliest days of crystal growth that kinetic processes of all Kinds control the nature of the growth. As the technology of crystal growth has become ever more refined, with the advent of such atomistic processes as molecular beam epitaxy, chemical vapor deposition, sputter deposition, and plasma enhanced techniques for the creation of “crystals” as little as one or a few atomic layers thick, multilayer structures, and novel materials combinations, the need to understand the mechanisms controlling the growth process is becoming more critical. Unfortunately, available techniques have not lent themselves well to obtaining a truly microscopic picture of such processes. Because of its atomic resolution on the one hand, and the achievable wide field of view on the other (of the order of micrometers) scanning tunneling microscopy (STM) gives us this opportunity. In this talk, we briefly review the types of growth kinetics measurements that can be made using STM. The use of STM for studies of kinetics is one of the more recent applications of what is itself still a very young field.

Design and verification of high-precision multi-star simulator with a wide field of view

2020 ◽  
Vol 13 (6) ◽  
pp. 1-9
Author(s):  
XU Hong-gang ◽  
◽  
HAN Bing ◽  
LI Man-li ◽  
MA Hong-tao ◽  
...  
Keyword(s):  
High Precision ◽  
Field Of View ◽  
Wide Field ◽  
Wide Field Of View

scholarly journals Strain Sensitivity Enhancement of Broadband Ultrasonic Signals in Plates Using Spectral Phase Filtering

2021 ◽  
Vol 11 (6) ◽  
pp. 2582
Author(s):  
Lucas M. Martinho ◽  
Alan C. Kubrusly ◽  
Nicolás Pérez ◽  
Jean Pierre von der Weid
Keyword(s):  
Fourier Transform ◽  
Guided Waves ◽  
Strain Level ◽  
Energy Concentration ◽  
Short Time Fourier Transform ◽  
Time Frequency ◽  
Frequency Representation ◽  
The Fourier Transform ◽  
Short Time ◽  
Sensitivity Gain

The focused signal obtained by the time-reversal or the cross-correlation techniques of ultrasonic guided waves in plates changes when the medium is subject to strain, which can be used to monitor the medium strain level. In this paper, the sensitivity to strain of cross-correlated signals is enhanced by a post-processing filtering procedure aiming to preserve only strain-sensitive spectrum components. Two different strategies were adopted, based on the phase of either the Fourier transform or the short-time Fourier transform. Both use prior knowledge of the system impulse response at some strain level. The technique was evaluated in an aluminum plate, effectively providing up to twice higher sensitivity to strain. The sensitivity increase depends on a phase threshold parameter used in the filtering process. Its performance was assessed based on the sensitivity gain, the loss of energy concentration capability, and the value of the foreknown strain. Signals synthesized with the time–frequency representation, through the short-time Fourier transform, provided a better tradeoff between sensitivity gain and loss of energy concentration.

An efficient short-time Fourier transform algorithm for grinding wheel condition monitoring through acoustic emission

2021 ◽  
Vol 113 (1-2) ◽  
pp. 585-603
Author(s):  
Wenderson N. Lopes ◽  
Pedro O. C. Junior ◽  
Paulo R. Aguiar ◽  
Felipe A. Alexandre ◽  
Fábio R. L. Dotto ◽  
...  
Keyword(s):  
Acoustic Emission ◽  
Fourier Transform ◽  
Condition Monitoring ◽  
Grinding Wheel ◽  
Short Time Fourier Transform ◽  
Short Time

Fourier Transform and Short-Time Fourier Transform Decomposition for Photovoltaic Arc Fault Detection

2020 ◽  
Author(s):  
Rahul Balamurugan ◽  
Fatima Al-Janahi ◽  
Oumaima Bouhali ◽  
Sawsan Shukri ◽  
Kais Abdulmawjood ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Fault Detection ◽  
Short Time Fourier Transform ◽  
Short Time
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