Path compression kd-trees with multi-layer parallel construction a case study on ray tracing

2017 ◽  
Author(s):  
Zonghui Li ◽  
Yangdong Deng ◽  
Ming Gu
Keyword(s):  
Ray Tracing ◽  
Parallel Construction

scholarly journals Characterisation of Indoor Massive MIMO Channels Using Ray-Tracing: A Case Study in the 3.2–4.0 GHz 5G Band

Electronics ◽  
2020 ◽  
Vol 9 (8) ◽  
pp. 1250
Author(s):  
Luis Valle ◽  
Jesús R. Pérez ◽  
Rafael P. Torres
Keyword(s):  
Ray Tracing ◽  
Massive Mimo ◽  
Base Station ◽  
Ofdm System ◽  
Mimo Channels ◽  
5G Systems ◽  
Target Environment ◽  
Temporal Dispersion ◽  
Measurement Campaigns

In this paper, research results on the applicability of ray-tracing (RT) techniques to model massive MIMO (MaMi) channels are presented and discussed. The main goal is to show the possibilities that site-specific models based on rigorous RT techniques, along with measurement campaigns considered for verification or calibration purposes where appropriate, can contribute to the development and deployment of 5G systems and beyond using the MaMi technique. For this purpose, starting from the measurements and verification of the simulator in a symmetric, rectangular and accessible scenario used as the testbed, the analysis of a specific case involving channel characterisation in a large, difficult access and measurement scenario was carried out using the simulation tool. Both the measurement system and the simulations emulated the up-link in an indoor cell in the framework of a MaMi-TDD-OFDM system, considering that the base station was equipped with an array consisting of 10 × 10 antennas. The comparison of the simulations with the measurements in the testbed environment allowed us to affirm that the accuracy of the simulator was high, both for determining the parameters of temporal dispersion and frequency selectivity, and for assessing the expected capacity in a specific environment. The subsequent analysis of the target environment showed the high capacities that a MaMi system can achieve in indoor picocells with a relatively high number of simultaneously active users.

Parry arc: a polarization lidar, ray-tracing, and aircraft case study

2000 ◽  
Vol 39 (36) ◽  
pp. 6738 ◽  
Author(s):  
Kenneth Sassen ◽  
Yoshihide Takano
Keyword(s):  
Ray Tracing

scholarly journals Discourse coherence: a case study of the French connector tandis que

2017 ◽  
Vol 13 (25) ◽  
pp. 93
Author(s):  
Mohammed Jadir
Keyword(s):  
Binary Relation ◽  
Functional Grammar ◽  
Discourse Marker ◽  
Semantic Level ◽  
Discourse Coherence ◽  
Discourse Model ◽  
Parallel Construction

This paper aims to explore the role of connectors in the degree of discourse coherence. Starting from Dik’s (1997: ch. 18) discourse model, I examine the extent to which connectors can adequately be accounted for in the theory of Functional Grammar through the study of the French particle tandis que. At the semantic level, tandis que is characterized as a circumstantial satellite marker be it locally or in a more global scope. As for pragmatic functions, it is argued that the Parallel Focus function singled out by tandis que can also be assigned to more than one element of a parallel construction when the contrast is not a binary relation. The last part of my paper is devoted to the textual functions of the discourse marker tandis que, which is relevant as a coherence-promoting device in introducing Topics or in signalling discourse discontinuity.

Application of the X-ray tracing method to powder diffraction line profiles

2008 ◽  
Vol 41 (1) ◽  
pp. 153-160 ◽  
Author(s):  
Sébastien Lambert ◽  
François Guillet
Keyword(s):  
Ray Tracing ◽  
Interesting Case ◽  
Detector Response ◽  
Instrument Function ◽  
Laboratory Equipment ◽  
X Ray ◽  
Dynamic Diffraction ◽  
Position Sensitive ◽  
Good Agreement

An X-ray tracing program was developed to simulate the instrument function of a high-resolution X-ray powder diffractometer. The optics of this laboratory instrument consist of a conventional X-ray tube, a single flat Ge monochromator, slits, the powder sample and finally a curved position-sensitive detector. Such a setup provides an interesting case study in order to assess X-ray tracing, which has seldom been used in the case of laboratory equipment. The simulation reported in this paper covers different aspects of optics simulation, ranging from straightforward kinematic diffraction to dynamic diffraction by single crystals or learned detector response function. The comparison between the simulation and the profiles measured using the NIST line profile standard SRM 660a LaB6shows a good agreement. This result provides the basis for discussing the opportunity of using X-ray tracing in diagram-refinement software.

scholarly journals Redirection of Lamb Waves for Structural Health Monitoring

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
W. H. Ong ◽  
W. K. Chiu
Keyword(s):  
Structural Health Monitoring ◽  
Ray Tracing ◽  
Health Monitoring ◽  
Lamb Wave ◽  
Lamb Waves ◽  
Design Stage ◽  
Structural Health ◽  
Critical Location ◽  
Potential Use

Currently, structures are designed without structural health monitoring (SHM) in mind. It is proposed that SHM should be addressed at the design stage of new structures. This paper explores the benefit which can be gained from such considerations. The scope encompasses Lamb-wave-based SHM and a given fatigue critical location (FCL). Optimization is performed using specialised ray tracing. A case study is carried out using a specimen that simulates a hard-to-inspect region in a fuel vent hole in wings structures of aircraft. This work will report on the potential use of the focussing of stress wave to improve detectability of defect in this hard-to-inspect location. Following optimization, results are produced numerically and experimentally. The results revealed sensitivity to damage is nearly doubled while minimum detectable damage size is significantly decreased. As a result, this study brings together an assortment of specialised tools to form a workflow ready for implementation.

Can we quantitatively image complex structures with rays?

Geophysics ◽  
2000 ◽  
Vol 65 (4) ◽  
pp. 1223-1238 ◽  
Author(s):  
M. Stéphane Operto ◽  
Sheng Xu ◽  
Gilles Lambaré
Keyword(s):  
Ray Tracing ◽  
Quantitative Estimation ◽  
Quantitative Imaging ◽  
Complex Structures ◽  
Deep Part ◽  
Prestack Depth Migration ◽  
Construction Technique ◽  
Future Studies ◽  
Depth Migration

Ray‐based prestack depth migration fails to image quantitatively complex structures when a single arrival—for example, the first or the strongest one—is taken into account. In this paper, we investigate whether accounting for multiple arrivals in ray‐based preserved amplitude prestack depth migration allows one to improve quantitative imaging of complex media. The asymptotic ray‐Born migration/inversion, originally designed to process one single arrival, is extended to the case of multiple arrivals by accounting for the cross‐contributions of all the source and receiver raypaths. Multiple arrivals in the folded ray fields are computed by a dynamic ray tracing based on a wavefront construction technique. With an application to the complex Marmousi model, we demonstrate that ray‐Born inversion can provide a reliable quantitative estimation of the relative impedance perturbation even in the complex deep part of the model, for which the amplitudes were underestimated drastically when only a single arrival was used, either the first or the strongest one. This 2-D case study shows that complex structures can be imaged quantitatively with rays. Future studies will require the optimizing of the implementation of ray‐Born migration/inversion with multiple arrivals before considering 3-D applications.

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