By judiciously selecting the TID parameters the ray tracing simulation reproduces the observed Doppler frequencies and AoAs. The TID is represented by a wavelike perturbation of the 3-D electron density traveling horizontally in the ionosphere with an amplitude that varies sinusoidally with time. Simulations are made using ray tracing through the International Reference Ionosphere (IRI) electron density model in an effort to reproduce measured signatures. Measuring the time variations of Doppler frequencies and angles of arrival (AoA) of ionospherically reflected HF waves has been proposed as a means of detecting the occurrence of traveling ionospheric disturbances (TIDs). A number of clarifying examples of multipathing in 2D media are examined.Д¬omparing TID simulations using 3-D ray tracing and mirror reflection One important advantage is its simplicity, in as much as any available or user-preferred initial value solver system can be used. Not only direct waves, but also reflected and head-waves can be incorporated in the scheme. The procedure is suitable for tracing rays through 2D complex structures, although it can be extended to deal with 3D velocity media. Using SA, the total traveltime is then globally minimized by obtaining the initial conditions that produce the absolute minimum path.

The last portion of the raypath is then forced to pass through the receiver. At each iteration, the ray is propagated from the source by solving a standard initial value problem. Problems related to: (1) the selection of new take-off angles, and (2) local minima in multipathing cases, are overcome by using an efficient simulated annealing (SA) algorithm. The algorithm overcomes some well known difficulties that arise in standard ray shooting and bending methods. We present a new method for solving the two-point seismic ray tracing problem based on Fermat's principle. Simulated annealing two-point ray tracing The program physcalc calculates the gravitational lensing shear using the relationship of convergence and shear, described by a set of coupled partial differential equations. Using MPI, ray_trace_ellipse may calculate deflection in parallel across network connected computers, such as cluster. The tool ray_trace_ellipse calculates deflection angles on a grid for light passing a deflecting mass distribution. The technical detail of the new method and simulation is presented with results and implication.Д¬osApps: Simulate gravitational lensing through ray tracing and shear calculationД¬osmology Applications (CosApps) provides tools to simulate gravitational lensing using two different techniques, ray tracing and shear calculation. Moreover, the simulation time of the new method was more than 20,000 times faster than the conventional ray equation method. Compared with the ray equation method, at Mach number 4 and 10Г‚В° LOS, the new method shows good agreement, generated 0.33% of relative root-mean-square (RMS) OPD difference and 0.22% of relative BSE difference. The variation of refractive index decreases, as the speed of flow field increases the OPD and its rate of decay at Mach number 6 in speed has somewhat larger value than at Mach number 4 in speed. The results show that optical path difference (OPD) and boresight error (BSE) decreases exponentially as LOS increases. Ray tracing simulation adopted the Snell's law in 3D to compute the paths of skew rays in the GRIN layers. The light source of ray set generated 3,228 rays for varying line of sight (LOS) from 10Г‚В° to 40Г‚В°. Each layer was modeled as a form of 2D polynomial by fitting the refractive index distribution. The grid refractive index of the flow field via CFD analysis and Gladstone-Dale relation was discretized into equally spaced layers which are parallel with the projectile's window. The condition for the steady-state solver conducted through computational fluid dynamics (CFD) included Mach numbers 4 and 6 in speed, 25 km altitude, and 0Г‚В° angle of attack (AoA). The cone-shaped projectile studied has 19Г‚В° semi-vertical angle a sapphire window is parallel to the cone angle and an optical system of the projectile was assumed via paraxial optics and infrared image detector.

The new method uses multiple gradient-index (GRIN) layers for construction of the anisotropic inhomogeneous media and ray tracing simulation. We present a new ray tracing simulation of aero-optical effect through anisotropic inhomogeneous media as supersonic flow field surrounds a projectile. Yang, Seul Ki Seong, Sehyun Ryu, Dongok Kim, Sug-Whan Kwon, Hyeuknam Jin, Sang-Hun Jeong, Ho Kong, Hyun Bae Lim, Jae Wan Choi, Jong Hwa Ray tracing simulation of aero-optical effect using multiple gradient index layer

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