scholarly journals Gamma-ray image reconstruction of the Andromeda galaxy

2021 ◽  
Vol 103 (8) ◽  
Author(s):  
Céline Armand ◽  
Francesca Calore
Keyword(s):  
Image Reconstruction ◽  
Gamma Ray ◽  
Andromeda Galaxy

scholarly journals Image Reconstruction Techniques in Neutron and Gamma Ray Spectroscopy: Improving Lunar Prospector Data

2018 ◽  
Vol 123 (7) ◽  
pp. 1804-1822 ◽  
Author(s):  
J. T. Wilson ◽  
D. J. Lawrence ◽  
P. N. Peplowski ◽  
J. T. S. Cahill ◽  
V. R. Eke ◽  
...  
Keyword(s):  
Image Reconstruction ◽  
Gamma Ray ◽  
Image Reconstruction Techniques ◽  
Lunar Prospector ◽  
Gamma Ray Spectroscopy

scholarly journals Polaris-LAMP: Multi-modal 3D Image Reconstruction with a Commercial Gamma-ray Imager

2021 ◽  
pp. 1-1
Author(s):  
J. Hecla ◽  
K. Knecht ◽  
D. Gunter ◽  
A. Haefner ◽  
D. Hellfeld ◽  
...  
Keyword(s):  
Image Reconstruction ◽  
Gamma Ray ◽  
3D Image ◽  
3D Image Reconstruction

scholarly journals Search for dark matter gamma-ray emission from the Andromeda Galaxy with the High-Altitude Water Cherenkov Observatory

2018 ◽  
Vol 2018 (06) ◽  
pp. 043-043 ◽  
Author(s):  
A. Albert ◽  
R. Alfaro ◽  
C. Alvarez ◽  
J.D. Álvarez ◽  
R. Arceo ◽  
...  
Keyword(s):  
Dark Matter ◽  
High Altitude ◽  
Gamma Ray ◽  
Andromeda Galaxy ◽  
Gamma Ray Emission

Measuring the Gas-Solids Distribution in Fluidized Beds -- A Review

2008 ◽  
Vol 6 (1) ◽  
Author(s):  
J. Ruud van Ommen ◽  
Robert F. Mudde
Keyword(s):  
Image Reconstruction ◽  
Fluidized Bed ◽  
Spatial Resolution ◽  
Fluidized Beds ◽  
Gamma Ray ◽  
Research Effort ◽  
Pressure Fluctuations ◽  
Local Pressure ◽  
Optical Probes ◽  
Measurement Volume

In gas-solid fluidized beds, the distribution of the particles typically varies both in time and space. Since the gas-solids distribution and its variation have a strong influence on the performance of a fluidized bed for a given process, it is very important to accurately measure the gas-solids or voidage distribution. This paper reviews techniques for measuring the voidage distribution in gas-solid fluidized beds, with a focus on the developments during the last ten years. We will treat subsequently direct visualisation, tomography, optical probes, capacitance probes, and pressure measurements.Dense gas-solids flows are typically opaque to visible light. This makes optical techniques only of limited use in dense gas-solids flow. However, direct visualization can be useful for very dilute systems, pseudo 2-D beds, and the outer layer of dense, 3-D systems. Tomography is frequently used to obtain the voidage distribution in a horizontal cross-section of the bed. Electric capacitance tomography is fast, but its spatial resolution is limited and image reconstruction is still troublesome. Although some steps forward have been made, research is continuing at this point. For nuclear (X-ray and gamma-ray) tomography, the image reconstruction is much easier and the spatial resolution better, but its temporal resolution is typically much lower. Therefore, research efforts for nuclear tomography are mainly aimed at increasing the measurement frequency. Optical probes determine the voidage as a function of time in a small measurement volume, either by the degree of reflection or by the degree of transmission of a light bundle. Capacitance probes determine the voidage as a function of time in a small measurement volume by measuring the dielectric permittivity of the gas-solids suspension in the measurement volume. Both optical and capacitance probe techniques are reasonably well-developed; the current research effort spent at improving them seems limited, especially for capacitance probes. Time-averaged pressure measurements are commonly used to determine the average bed density and bed height. By sampling the local pressure at a sufficiently high frequency (typically in the order of 200 Hz), much more information can be obtained about the fluidized bed hydrodynamics. However, obtaining quantitative voidage data from pressure fluctuations measurement remains a difficult task; in-bed pressure fluctuation (and acoustic) measurements are mostly used to determine changes in the voidage dynamics and distribution.

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