The use of a large-aperture radio system for meteor studies

1980 ◽  
Vol 58 (6) ◽  
pp. 779-787 ◽  
Author(s):  
R. W. Herring ◽  
P. A. Forsyth

A large sampled-aperture antenna array has been used to investigate the structure of the radio wave field scattered by meteor trails. The experiment measured the phase and amplitude of the radio waves in the frequency range 20 to 30 MHz at 58 points distributed over an aperture of almost 1.2 km. The temporal changes in the structure of the scattered radiation clearly show the influence of distortion of the meteor trails by atmospheric winds, but are incompatible with the widely accepted model which attributes fading and anomalous decay times to the distortion of a single trail. The observations seem to imply the simultaneous existence of two or more trails but whether these trails are due to fragmentation of the meteoroid in the atmosphere or to simultaneous entry of independent meteoroids is not clear.

1973 ◽  
Vol 26 (6) ◽  
pp. 815 ◽  
Author(s):  
RA Vincent

Possible shapes and spatial scales of ionospheric irregularities in the lower ionosphere have been determined from analyses of two sets of radio wave back-scattering observations: measurements of the spatial scale of the ground pattern of the wave field back-scattered from altitudes near 95 km and measurements of the amount and angular distribution of power back-scattered from solitary horizontally-moving irregularities at altitudes near 75 km. At 95 km the irregularities are anisotropic, with larger horizontal than vertical dimensions. For an assumed Gaussian distribution of ionization, the inferred axial ratio (horizontal to vertical) is about three. It is tentatively concluded that the irregularities at 75 km are sharply bounded and are some kilometres in horizontal extent.


2021 ◽  
Vol 195 ◽  
pp. 105135
Author(s):  
I. Lapshina ◽  
S. Kalabanov ◽  
A. Karpov ◽  
A. Sulimov
Keyword(s):  

Sensors ◽  
2020 ◽  
Vol 21 (1) ◽  
pp. 83
Author(s):  
Keiichi Zempo ◽  
Taiga Arai ◽  
Takuya Aoki ◽  
Yukihiko Okada

To evaluate and improve the value of a service, it is important to measure not only the outcomes, but also the process of the service. Value co-creation (VCC) is not limited to outcomes, especially in interpersonal services based on interactions between actors. In this paper, a sensing framework for a VCC process in retail stores is proposed by improving an environment recognition based indoor positioning system with high positioning performance in a metal shelf environment. The conventional indoor positioning systems use radio waves; therefore, errors are caused by reflection, absorption, and interference from metal shelves. An improvement in positioning performance was achieved in the proposed method by using an IR (infrared) slit and IR light, which avoids such errors. The system was designed to recognize many and unspecified people based on the environment recognition method that the receivers had installed, in the service environment. In addition, sensor networking was also conducted by adding a function to transmit payload and identification simultaneously to the beacons that were attached to positioning objects. The effectiveness of the proposed method was verified by installing it not only in an experimental environment with ideal conditions, but posteriorly, the system was tested in real conditions, in a retail store. In our experimental setup, in a comparison with equal element numbers, positioning identification was possible within an error of 96.2 mm in a static environment in contrast to the radio wave based method where an average positioning error of approximately 648 mm was measured using the radio wave based method (Bluetooth low-energy fingerprinting technique). Moreover, when multiple beacons were used simultaneously in our system within the measurement range of one receiver, the appropriate setting of the pulse interval and jitter rate was implemented by simulation. Additionally, it was confirmed that, in a real scenario, it is possible to measure the changes in movement and positional relationships between people. This result shows the feasibility of measuring and evaluating the VCC process in retail stores, although it was difficult to measure the interaction between actors.


1977 ◽  
Vol 20 (12) ◽  
pp. 1267-1270 ◽  
Author(s):  
Yu. A. Ignat'ev ◽  
Z. N. Krotova ◽  
�. E. Mityakova

2008 ◽  
Vol 26 (11) ◽  
pp. 3439-3443 ◽  
Author(s):  
A. P. Ballinger ◽  
P. B. Chilson ◽  
R. D. Palmer ◽  
N. J. Mitchell

Abstract. The decay of underdense meteor trails in the polar mesopause region is thought to be predominantly due to ambipolar diffusion, a process governed by the ambient temperature and pressure. Hence, observations of meteor decay times have been used to indirectly measure the temperature of the mesopause region. Using meteor observations from a SKiYMET radar in northern Sweden during 2005, this study found that weaker meteor trails have shorter decay times (on average) than relatively stronger trails. This suggests that processes other than ambipolar diffusion can play a significant role in trail diffusion. One particular mechanism, namely electron-ion recombination, is explored. This process is dependent on the initial electron density within the meteor trail, and can lead to a disproportionate reduction in decay time, depending on the strength of the meteor.


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