scholarly journals Prediction of Target Detection Probability Based on Air-to-Air Long-Range Scenarios in Anomalous Atmospheric Environments

2021 ◽  
Vol 13 (19) ◽  
pp. 3943
Author(s):  
Tae-Heung Lim ◽  
Hosung Choo
Keyword(s):  
Long Range ◽  
Target Detection ◽  
Cross Section ◽  
Detection Probability ◽  
Path Loss ◽  
Atmospheric Environment ◽  
Airborne Radar ◽  
Prediction System ◽  
Range Equation ◽  
Rainfall Attenuation

We investigate a target detection probability (TDP) using path loss of an airborne radar based on air-to-air scenarios in anomalous atmospheric and weather environments. In the process of calculating the TDP, it is necessary to obtain the overall path loss including the anomalous atmospheric environment, gas attenuation, rainfall attenuation, and beam scanning loss. The path loss including the quad-linear refractivity model and other radar input parameters is simulated using the Advanced Refractive Effects Prediction System (AREPS) software along the range and the altitude. For the gas and rainfall attenuations, ITU-R models are used to consider the weather environment. In addition, the radar beam scan loss and a radar cross section (RCS) of the target are considered to estimate the TDP of the airborne long-range radar. The TDP performance is examined by employing the threshold evaluations of the total path loss derived from the detectability factor and the free-space radar range equation. Finally, the TDPs are obtained by assuming various air-to-air scenarios for the airborne radar in anomalous atmospheric and weather environments.

scholarly journals Analysis of the Target Detection Performance of Air-to-Air Airborne Radar Using Long-Range Propagation Simulation in Abnormal Atmospheric Conditions

2020 ◽  
Vol 10 (18) ◽  
pp. 6440
Author(s):  
Tea Heung Lim ◽  
Minho Go ◽  
Chulhun Seo ◽  
Hosung Choo
Keyword(s):  
Long Range ◽  
Target Detection ◽  
Path Loss ◽  
Detection Performance ◽  
Airborne Radar ◽  
Atmospheric Conditions ◽  
Propagation Characteristics ◽  
Digital Terrain ◽  
Elevation Data ◽  
Terrain Elevation

In this paper, we propose the analysis of the target detection performance of air-to-air airborne radars using long-range propagation simulations with a novel quad-linear refractivity model under abnormal atmospheric conditions. The radar propagation characteristics and the target detection performance are simulated using the Advanced Refractive Effects Prediction System (AREPS) software, where the refractivity along the altitude, array antenna pattern, and digital terrain elevation data are considered as inputs to obtain the path loss of the wave propagation. The quad-linear model is used to approximate the actual refractivity data, which are compared to the data derived using the conventional trilinear refractivity model. On the basis of the propagation simulations, we propose a detection performance metric in terms of the atmosphere (DPMA) for intuitively examining the long-range propagation characteristics of airborne radars in air-to-air situations. To confirm the feasibility of using the DPMA map in various duct scenarios, we employ two actual refractive indices to observe the DPMA results in relation to the height of the airborne radar.

Electro-optical detection probability of optical devices determined by bidirectional laser retro-reflection cross section

2015 ◽  
Author(s):  
Martin Laurenzis ◽  
Frank Christnacher ◽  
Alexis Matwyschuk ◽  
Stephane Schertzer ◽  
Sebastien Hengy
Keyword(s):  
Cross Section ◽  
Detection Probability ◽  
Optical Detection ◽  
Optical Devices

scholarly journals ORDERING IN DENSE FIBER BUNDLES, THE PHYLLOTACTIC SOLUTION AND ITS APPLICATION TO COLLAGEN FIBRILS

2013 ◽  
Vol 08 (01n02) ◽  
pp. 33-49 ◽  
Author(s):  
JEAN CHARVOLIN ◽  
JEAN-FRANÇOIS SADOC
Keyword(s):  
Long Range ◽  
Cross Section ◽  
Type I Collagen ◽  
Radial Symmetry ◽  
Collagen Fibrils ◽  
Fiber Bundles ◽  
Type I ◽  
High Symmetry ◽  
Structural Studies ◽  
Packing Efficiency

The shape of the cross section of a dense fiber bundle is related to the symmetry of its molecular packing. However, this statement might be belied by type I collagen fibrils which have a rounded section of high symmetry while structural studies suggest that their molecules are assembled with a long range lateral order of lower symmetry. We examine how phyllotaxis, which is a nonconventional crystallographic solution to packing efficiency in situations of high radial symmetry, can establish a link between those two apparently conflicting points. The lateral order imposed by the algorithm of phyllotaxis, which implies an enlargement of the notion of long range lateral order beyond that used for classical crystals, provides a basis for a new analysis of the experimental data.

scholarly journals Comparison of Three Different Styles of Submarine Sails on Electromagnetic Scattering under the Detection of Airborne Radar

2018 ◽  
Vol 17 ◽  
pp. 02003
Author(s):  
Ji Liu ◽  
Peilin Huang ◽  
Yaodong Zhao ◽  
Jinzu Ji ◽  
Fengli Xue
Keyword(s):  
Cross Section ◽  
Electromagnetic Scattering ◽  
Pitch Angle ◽  
Elevation Angle ◽  
3D Models ◽  
Radar Cross Section ◽  
Physical Optics ◽  
Airborne Radar ◽  
Range Analysis ◽  
Radar Antenna

This paper studies radar cross section of submarine sails on the water. Under the detection of the enemy’s airborne radar, considering the motion of the submarine, the sail model of radar pitch angle incidence range analysis is established. By using CATIA software, the 3D models of AKULA sail, SUBOFF sail and VICTOR sail are built. On the basis of the physical optics method and the equivalent currents method, the scattering characteristics of sails RCS(radar cross section) are simulated under X radar band. Through the microwave anechoic chamber test, this paper verifies the accuracy of the combination of the physical optics method and the equivalent electromagnetic flow method. The influence of the distance from the airborne radar to the sail on the pitch angle of the electromagnetic wave is discussed, with the elevation angle of the radar antenna varies. Then, we illustrate the characteristics of circumferential direction RCS of the sail under different pitch angles. Finally, the mean RCS of the sail at a given pitch angle is simulated. The results show that the AKULA sail is considerably superior to SUBOFF sail and VICTOR sail on stealth performance with the pitch angle less than 4° . But when the pitch angle exceeds 10°, the SUBOFF sail can be given priority.

Study of Effects of Long-Range Transport of Air Pollutants on the Atmospheric Environment

2014 ◽  
Vol 955-959 ◽  
pp. 1341-1345 ◽  
Author(s):  
Xia Zhang ◽  
Liang Tian ◽  
Xian Sun ◽  
Chuang Ye Jiang
Keyword(s):  
Air Quality ◽  
Long Range ◽  
Air Pollutants ◽  
Concentration Field ◽  
Atmospheric Environment ◽  
Shanxi Province ◽  
Long Range Transport ◽  
Flux Method ◽  
Range Transport ◽  
Pollutants Transport

Based on meteorological field output by MM5 mesoscale meteorological model and concentration field output by CALPUFF air quality model, “flux method” was applied to study effects of long-range transport of air pollutants on the atmospheric environment, in which micro-element method was used to solve the process of air pollutants transport in long-range of three-dimensional space. This method was first applied in studying a construction project’s impact on air quality in Guanzhong region of Shanxi Province. The results shows that the deviation of flux method is less which the value is 16 percent, and among all year around, the pollutants transport the more flux to the ENE and WSW directions of the project compared to other directions. Additional, the flux of fall and winter is more than it of spring and summer, and the project has a more severe influence of atmospheric environment in Xi’an city than it of Weinan city.

scholarly journals An Analysis of the Nonstationarity in the Bias of Sea Surface Temperature Forecasts for the NCEP Climate Forecast System (CFS) Version 2

2012 ◽  
Vol 140 (9) ◽  
pp. 3003-3016 ◽  
Author(s):  
A. Kumar ◽  
M. Chen ◽  
L. Zhang ◽  
W. Wang ◽  
Y. Xue ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Long Range ◽  
Initial Conditions ◽  
Sea Surface ◽  
Climate Forecast ◽  
Prediction System ◽  
Forecast System ◽  
Climate Forecast System ◽  
Forecast Bias

Abstract For long-range predictions (e.g., seasonal), it is a common practice for retrospective forecasts (also referred to as the hindcasts) to accompany real-time predictions. The necessity for the hindcasts stems from the fact that real-time predictions need to be calibrated in an attempt to remove the influence of model biases on the predicted anomalies. A fundamental assumption behind forecast calibration is the long-term stationarity of forecast bias that is derived based on hindcasts. Hindcasts require specification of initial conditions for various components of the prediction system (e.g., ocean, atmosphere) that are generally taken from a long reanalysis. Trends and discontinuities in the reanalysis that are either real or spurious can arise due to several reasons, for example, the changing observing system. If changes in initial conditions were to persist during the forecast, there is a potential for forecast bias to depend over the period it is computed, making calibration even more of a challenging task. In this study such a case is discussed for the recently implemented seasonal prediction system at the National Centers for Environmental Prediction (NCEP), the Climate Forecast System version 2 (CFS.v2). Based on the analysis of the CFS.v2 for 1981–2009, it is demonstrated that the characteristics of the forecast bias for sea surface temperature (SST) in the equatorial Pacific had a dramatic change around 1999. Furthermore, change in the SST forecast bias, and its relationship to changes in the ocean reanalysis from which the ocean initial conditions for hindcasts are taken is described. Implications for seasonal and other long-range predictions are discussed.

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