scholarly journals Detection of Aircraft Touchdown Using Longitudinal Acceleration and Continuous Wavelet Transformation

Sensors ◽  
2020 ◽  
Vol 20 (24) ◽  
pp. 7231
Author(s):  
Jerzy Bakunowicz ◽  
Paweł Rzucidło
Keyword(s):  
Wavelet Transformation ◽  
Precise Determination ◽  
Landing Gear ◽  
Continuous Wavelet ◽  
Passenger Compartment ◽  
Aircraft Structure ◽  
Longitudinal Acceleration ◽  
Structural Parts ◽  
The Moment

The paper presents a methodology enabling the detection of aircraft touchdowns based on data obtained from accelerometers attached to the structural parts of the airframe in the cockpit or passenger compartment. Precise determination of the moment and place of touchdown of the main landing gear is challenging when analysing parameters such as height, flight speed and rate of descent. During the tests of the I-31T aircraft, it turned out that vibrations of the aircraft structure caused by the contact of the front and main landing gear with the ground have a repetitive character. In particular, this applies to longitudinal acceleration. The use of continuous wavelet analysis (CWT) allowed finding unique periodic features of the landing phenomenon that distinguish it from other forms of vibration occurring in individual flight phases. Ground and flight observations of experimental aeroplane MP-02 Czajka verified the proposed method of virtual touchdown detection. The results presented in this paper justify that this method may find broader application, especially for the light aircraft class.

Seismicity in the vicinity of the SNORCLE corridors of the northern Canadian Cordillera

2005 ◽  
Vol 42 (6) ◽  
pp. 1137-1148 ◽  
Author(s):  
John F Cassidy ◽  
Garry C Rogers ◽  
J Ristau
Keyword(s):  
Current Knowledge ◽  
Active Faults ◽  
Active Regions ◽  
Large Earthquake ◽  
Historical Earthquakes ◽  
Precise Determination ◽  
Canadian Cordillera ◽  
Waveform Modelling ◽  
The Moment

The Slave – Northern Cordillera Lithospheric Evolution (SNORCLE) corridors of the northern Cordillera sample some of the most, and least, seismically active regions of Canada. The earthquake history of this region is short. Precise determination of earthquake locations and depths is not possible even today. Nonetheless, significant gains in our knowledge of the seismicity of this region have been made in recent years from studies of historic earthquakes, microseismicity studies, and advances in waveform modelling techniques combined with broadband data that allow for determination of focal mechanisms and depths for moderate earthquakes. This article summarizes our current knowledge of the seismicity and seismic hazards across the region. These detailed analyses have shown that (i) the largest historical earthquakes have occurred in regions of ongoing microseismicity; (ii) the largest earthquakes have occurred in pairs or in swarms, suggesting that stress triggering is important in this region; (iii) the active faults are concentrated in the offshore region; (iv) there is a concentration of seismicity in the Fold and Thrust belt, several hundred kilometres from the active plate margin; and (v) there is no seismicity associated with the Quaternary volcanic zone in northern British Columbia. Potentially damaging (magnitude M ≥ 5) earthquakes can be expected every few years in the vicinity of the northern Cordillera. The Mw = 7.9 Denali, Alaska, earthquake (where Mw is the moment magnitude) was a good reminder that the effects of a large earthquake can be substantial, even hundreds of kilometres from the epicentre. Detailed studies of seismicity, earth structure, and tectonics, with the latter made possible in large part by the SNORCLE transect, will allow for informed decision-making for resource development and the design of safe structures and infrastructure in the northern Canadian Cordillera.

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