scholarly journals The Spectral Power Density and Shadowing Function of a Glacial Microrelief at the Decimetre Scale

1979 ◽  
Vol 23 (89) ◽  
pp. 57-66 ◽  
Author(s):  
J.-P. Benoist

Abstract Longitudinal profiles of roches moutonnées have been measured once every centimetre over a total length of more than 100 m. Only wavelengths in the range 3.6 cm < λ < 40 cm have been kept and analysed. Levels and their slopes have a symmetrical, non-Gaussian distribution. The spectral power density varies roughly as γ 0 ν–n (ν ═ wavenumber ═ 1/λ); n being the same for all the profiles (n ═ 2.36) and γ 0 being dependent on the studied area. No significant difference has been found for the shadowing function of the different studied areas. It differs consistently from Smith’s theoretical function.

1979 ◽  
Vol 23 (89) ◽  
pp. 57-66 ◽  
Author(s):  
J.-P. Benoist

AbstractLongitudinal profiles of roches moutonnées have been measured once every centimetre over a total length of more than 100 m. Only wavelengths in the range 3.6 cm < λ < 40 cm have been kept and analysed. Levels and their slopes have a symmetrical, non-Gaussian distribution. The spectral power density varies roughly as γ0ν–n (ν ═ wavenumber ═ 1/λ); n being the same for all the profiles (n ═ 2.36) and γ0 being dependent on the studied area. No significant difference has been found for the shadowing function of the different studied areas. It differs consistently from Smith’s theoretical function.


Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4215
Author(s):  
Radosław Wróbel ◽  
Lech Sitnik ◽  
Monika Andrych-Zalewska ◽  
Łukasz Łoza ◽  
Radostin Dimitrov ◽  
...  

The article presents the results of research on the vibroacoustic response of internal combustion engines mounted in a vehicle. The vehicles studied belong to popular models, which became available in successive versions. Each group included vehicles of the same model of an older generation (equipped with a naturally aspirated engine) and of a newer generation, including downsized (and turbocharged) engines. Tests in each group were carried out under repeatable conditions on a chassis-load dynamometer. The vibrations were measured using single-axis accelerometers mounted on the steering wheel, engine, and driver’s head restraint mounting. The primary purpose of the study was to verify whether the new generations of vehicles equipped with additional high-speed elements (compressors) generate additional harmonics (especially those within the range potentially affecting travel comfort and human health) and whether there are significant changes in the distribution of spectral power density in the new generations. As the study showed, new generations of vehicles are characterized by a different vibroacoustic response, and the trend of change is the same in each of the families studied.


2020 ◽  
Vol 22 (4) ◽  
pp. 651-657
Author(s):  
Javier Castilla-Gutiérrez ◽  
Juan Carlos Fortes ◽  
Jose Miguel Davila

2019 ◽  
Vol 20 (14) ◽  
pp. 3486 ◽  
Author(s):  
Julian I. Hofmann ◽  
Cornelius Schwarz ◽  
Uwe Rudolph ◽  
Bernd Antkowiak

Patterns of spontaneous electric activity in the cerebral cortex change upon administration of benzodiazepines. Here we are testing the hypothesis that the prototypical benzodiazepine, diazepam, affects spectral power density in the low (20–50 Hz) and high (50–90 Hz) γ-band by targeting GABAA receptors harboring α1- and α2-subunits. Local field potentials (LFPs) and action potentials were recorded in the barrel cortex of wild type mice and two mutant strains in which the drug exclusively acted via GABAA receptors containing either α1- (DZα1-mice) or α2-subunits (DZα2-mice). In wild type mice, diazepam enhanced low γ-power. This effect was also evident in DZα2-mice, while diazepam decreased low γ-power in DZα1-mice. Diazepam increased correlated local LFP-activity in wild type animals and DZα2- but not in DZα1-mice. In all genotypes, spectral power density in the high γ-range and multi-unit action potential activity declined upon diazepam administration. We conclude that diazepam modifies low γ-power in opposing ways via α1- and α2-GABAA receptors. The drug’s boosting effect involves α2-receptors and an increase in local intra-cortical synchrony. Furthermore, it is important to make a distinction between high- and low γ-power when evaluating the effects of drugs that target GABAA receptors.


Sign in / Sign up

Export Citation Format

Share Document