scholarly journals RF Field Build-Up inside a Manned Space Vehicle Using Novel Ray-Tracing Algorithm

2013 ◽  
Vol 2013 ◽  
pp. 1-9
Author(s):  
Balamati Choudhury ◽  
Hema Singh ◽  
R. M. Jha
Keyword(s):  
Ray Tracing ◽  
Space Vehicle ◽  
Complex Problem ◽  
Image Method ◽  
Propagation Time ◽  
Vehicle Cabin ◽  
Paraboloid Of Revolution ◽  
Manned Space ◽  
Ray Path ◽  
Ray Launching

The radio-frequency (RF) field mapping and its analysis inside a space vehicle cabin, although of immense importance, represent a complex problem due to their inherent concavity. Further hybrid surface modeling required for such concave enclosures leads to ray proliferation, thereby making the problem computationally intractable. In this paper, space vehicle is modeled as a double-curvatured general paraboloid of revolution (GPOR) frustum, whose aft section is matched to an end-capped right circular cylinder. A 3D ray-tracing package is developed which involves a uniform ray-launching scheme, an intelligent scheme for ray bunching, and an adaptive reception algorithm for obtaining ray-path details inside the concave space vehicle. Due to nonavailability of image method for concave curvatured surfaces, the proposed ray-tracing method is validated with respect to the RF field build-up inside a closed lossy cuboid using image method. The RF field build-up within the space vehicle is determined using the details of ray paths and the material parameters. The results for RF field build-up inside a metal-backed dielectric space vehicle are compared with those of highly metallic one for parallel and perpendicular polarizations. The convergence of RF field within the vehicle is analyzed with respect to the propagation time and the number of bounces a ray undergoes before reaching the receiving point.

scholarly journals Simple and Exact Closed-Form Expression for Determination of a Penetrated Ray Path in a Ray Tracing

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Hyun Wook Moon ◽  
Woojoong Kim ◽  
Sewoong Kwon ◽  
Jaeheung Kim ◽  
Young Joong Yoon
Keyword(s):  
Closed Form ◽  
Approximate Method ◽  
Ray Tracing ◽  
Conventional Method ◽  
Closed Form Expression ◽  
Indoor Environments ◽  
Straight Line ◽  
Ray Path ◽  
Ray Tracing Simulation

A simple and exact closed-form equation to determine a penetrated ray path in a ray tracing is proposed for an accurate channel prediction in indoor environments. Whereas the penetrated ray path in a conventional ray tracing is treated as a straight line without refraction, the proposed method is able to consider refraction through the wall in the penetrated ray path. Hence, it improves the accuracy in ray tracing simulation. To verify the validation of the proposed method, the simulated results of conventional method, approximate method, and proposed method are compared with the measured results. The comparison shows that the proposed method is in better agreement with the measured results than the conventional method and approximate method, especially in high frequency bands.

The Development of a Parallel Ray Launching Algorithm for Wireless Network Planning

2012 ◽  
pp. 466-483
Author(s):  
Zhihua Lai ◽  
Nik Bessis ◽  
Guillaume De La Roche ◽  
Pierre Kuonen ◽  
Jie Zhang ◽  
...  
Keyword(s):  
Ray Tracing ◽  
Wireless Network ◽  
Real World ◽  
Network Planning ◽  
Time Constraint ◽  
Running Time ◽  
Propagation Modeling ◽  
Physical Resources ◽  
Ray Launching

Propagation modeling has attracted much interest because it plays an important role in wireless network planning and optimization. Deterministic approaches such as ray tracing and ray launching have been investigated, however, due to the running time constraint, these approaches are still not widely used. In previous work, an intelligent ray launching algorithm, namely IRLA, has been proposed. The IRLA has proven to be a fast and accurate algorithm and adapts to wireless network planning well. This article focuses on the development of a parallel ray launching algorithm based on the IRLA. Simulations are implemented, and evaluated performance shows that the parallelization greatly shortens the running time. The COST231 Munich scenario is adopted to verify algorithm behavior in real world environments, and observed results show a 5 times increased speedup upon a 16-processor cluster. In addition, the parallelization algorithm can be easily extended to larger scenarios with sufficient physical resources.

scholarly journals Aerodynamic Analysis of a Manned Space Vehicle for Missions to Mars

2011 ◽  
Vol 2011 ◽  
pp. 1-13 ◽  
Author(s):  
Giuseppe Pezzella ◽  
Antonio Viviani
Keyword(s):  
Aerodynamic Drag ◽  
Three Dimensional ◽  
Space Vehicle ◽  
Mars Atmosphere ◽  
Aerodynamic Analysis ◽  
Braking System ◽  
Wide Range ◽  
Real Gas Effects ◽  
Manned Space ◽  
Dynamics Analyses

The paper deals with the aerodynamic analysis of a manned braking system entering the Mars atmosphere with the aim to support planetary entry system design studies. The exploration vehicle is an axisymmetric blunt body close to the Apollo capsule. Several fully three-dimensional computational fluid dynamics analyses have been performed to address the capsule aerodynamic performance. To this end, a wide range of flow conditions including reacting and nonreacting flow, different angles of attack, and Mach numbers have been investigated and compared. Moreover, nonequilibrium effects on the flow field around the entry vehicle have also been investigated. Results show that real-gas effects, for all the angles of attack considered, increase both the aerodynamic drag and pitching moment whereas the lift is only slighted affected. Finally, results comparisons highlight that experimental and CFD aerodynamic findings available for the Apollo capsule in air adequately represent the static coefficients of the capsule in the Mars atmosphere.

3D anisotropic ray tracing by ray path optimization

2008 ◽  
Author(s):  
Lorenzo Casasanta ◽  
Giuseppe Drufuca ◽  
Clara Andreoletti ◽  
Jacopo Panizzardi
Keyword(s):  
Ray Tracing ◽  
Path Optimization ◽  
Ray Path

scholarly journals Application Of Finite Difference Eikonal Solver For Traveltime Computation In Forward Modeling And Migration

2021 ◽  
Vol 72 ◽  
pp. 113-122
Author(s):  
Amir Mustaqim Majdi ◽  
◽  
Seyed Yaser Moussavi Alashloo ◽  
Nik Nur Anis Amalina Nik Mohd Hassan ◽  
Abdul Rahim Md Arshad ◽  
...  
Keyword(s):  
Wave Equation ◽  
Finite Difference ◽  
Ray Tracing ◽  
Forward Modeling ◽  
Fast Marching ◽  
Seismic Image ◽  
And Migration ◽  
Ray Path ◽  
Seismic Images ◽  
Tracing Method

Traveltime is one of the propagating wave’s components. As the wave propagates further, the traveltime increases. It can be computed by solving wave equation of the ray path or the eikonal wave equation. Accurate method of computing traveltimes will give a significant impact on enhancing the output of seismic forward modeling and migration. In seismic forward modeling, computation of the wave’s traveltime locally by ray tracing method leads to low resolution of the resulting seismic image, especially when the subsurface is having a complex geology. However, computing the wave’s traveltime with a gridding scheme by finite difference methods able to overcomes the problem. This paper aims to discuss the ability of ray tracing and fast marching method of finite difference in obtaining a seismic image that have more similarity with its subsurface model. We illustrated the results of the traveltime computation by both methods in form of ray path projection and wavefront. We employed these methods in forward modeling and compared both resulting seismic images. Seismic migration is executed as a part of quality control (QC). We used a synthetic velocity model which based on a part of Malay Basin geology structure. Our findings shows that the seismic images produced by the application of fast marching finite difference method has better resolution than ray tracing method especially on deeper part of subsurface model.

scholarly journals Results of the Development of the Research Prototype of the Interactive Electronic Technical Guide for the MSV Simulator.

2021 ◽  
pp. 61-71
Author(s):  
A.I. Zhokhov
Keyword(s):  
Space Vehicle ◽  
Manned Space ◽  
Technical Guide ◽  
Research Prototype

The paper considers the designation and requirement for the research prototype of the interactive electronic Technical Guide for the simulator of the Manned Space Vehicle (MSV) as well as the results of its development.

Rapid solution of ray tracing problems in heterogeneous media

1980 ◽  
Vol 70 (4) ◽  
pp. 1137-1148 ◽  
Author(s):  
C. H. Thurber ◽  
W. L. Ellsworth
Keyword(s):  
Travel Time ◽  
Ray Tracing ◽  
Heterogeneous Media ◽  
Velocity Structure ◽  
Minimum Time ◽  
Local Minima ◽  
Complex Velocity ◽  
Efficient Manner ◽  
Tracing Techniques ◽  
Ray Path

abstract The determination of local earthquake hypocenters and orgin times from first-P-arrival times by Geiger's method requires a technique for finding the minimum travel time (and derivatives) between the source and the station. Sophisticated ray tracing techniques have been developed for this purpose for use in complex velocity structures. Unfortunately, the two common techniques, shooting and bending, are generally prohibitively expensive for routine use in data analysis. The bending method is also particularly vulnerable to the problem of local minima in travel time. A method has been developed known as the ray initializer, which can be used to circumvent these problems in many cases. First, the technique can find a reasonable estimate of the minimum-time ray path in a quick and efficient manner. The velocity in a region local to the source and receiver is laterally averaged to yield an approximate layered velocity model. One-dimensional ray tracing techniques are used to find the minimum-time path for this layered structure. The ray path estimate can then be used as the starting path in a bending routine, a procedure resulting in more rapid convergence and the avoidance of local minima. Second, the travel time found by numerical integration along the estimated ray path is an excellent approximation to the actual travel time. Thus, in many cases, the ray initializer can be substituted for a three-dimensional ray tracing routine with a tremendous increase in efficiency and only a small loss in accuracy. It is found that the location of an explosion, derived using the ray initializer, is nearly identical to a complete ray tracing solution, even for a highly complex velocity structure.

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