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    Wyświetlanie 1-22 z 22
    Tytuł:
    Numerical methods in underwater acoustics - sound propagation and backscattering
    Autorzy:
    Nolte, B.
    Ehrlich, J.
    Hofmann, H.-G.
    Schäfer, I.
    Schäfke, A.
    Stoltenberg, A.
    Burgschweiger, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/331712.pdf
    Data publikacji:
    2015
    Wydawca:
    Polskie Towarzystwo Akustyczne
    Tematy:
    stochastic ray tracing
    German Navy
    Opis:
    This report summarizes an overview given at the XXXII Symposium on Hydroacoustics (SHA 2015) over several modelling techniques that are used in the context of military applications at the Research Department FWG of the German Bundeswehr Technical Centre for Ships and Naval Weapons, Maritime Technology and Research (WTD 71). For the modelling and understanding of sound propagation a physical model consisting of a tank for scaled measurements and the corresponding numerical simulation is presented. The basic formalism of stochastic ray tracing of the German Navy sonar simulation MOCASSIN is explained and compared to traditional deterministic ray tracing including the comparison with measurements. Strategies for the approximate calculation of the sonar target strength of large underwater objects with the use of boundary element methods, fast multipole methods and a ray-based algorithm are presented and the results of the calculations of several test objects are shown.
    Źródło:
    Hydroacoustics; 2015, 18; 127-140
    1642-1817
    Pojawia się w:
    Hydroacoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Monte Carlo simulation of SiO2 nanoparticle-coated polymer optical fiber humidity sensor by ray tracing
    Autorzy:
    Kovacevic, Milan S.
    Milosevic, Marko M.
    Kuzmanovic, Ljubica
    Djordjevich, Alexandar
    Powiązania:
    https://bibliotekanauki.pl/articles/1835775.pdf
    Data publikacji:
    2020
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    optical fiber
    humidity
    ray propagation
    ray tracing
    Opis:
    A fiber optic device sensitive to humidity is detailed and modelled by ray tracing based on Monte Carlo simulation. The device is intended primarily for monitoring humidity in the microenvironment of wounds without removing the wound dressing and thus disturbing the wound-healing process. To produce the sensor, cladding is removed from a segment of its polymer-fiber and mesoporous SiO2 nanoparticles are deposited in the exposed zone. This introduces an additional light-transmission loss. The extent of such loss is related to the relative humidity of the environment. Such a relationship, embodying the essence of the sensor’s modulation principle, is examined in this paper by ray tracing based on Monte Carlo simulation. The sensor is explained in detail and its performance is characterised.
    Źródło:
    Optica Applicata; 2021, 51, 2; 281-288
    0078-5466
    1899-7015
    Pojawia się w:
    Optica Applicata
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Novel Tracing Algorithm vs Remcom Wireless InSite
    Autorzy:
    Gotszald, Ł.
    Powiązania:
    https://bibliotekanauki.pl/articles/963894.pdf
    Data publikacji:
    2015
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    Ray Tracing
    radio wave propagation modelling
    Opis:
    Results of comparison between a popular commercial software for radio wave propagation modeling versus prototype implementation of a novel algorithm proposed by the author of this paper is discussed. It is shown that both algorithms lead to very similar results while the new one is faster by a few orders of magnitude.
    Źródło:
    International Journal of Electronics and Telecommunications; 2015, 61, 3; 273-279
    2300-1933
    Pojawia się w:
    International Journal of Electronics and Telecommunications
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Sea-bed scattering and reflection contributions to the short-range acoustic impulse response: measurements and modelling
    Autorzy:
    Ivansson, S.
    Karlsson, P. A.
    Powiązania:
    https://bibliotekanauki.pl/articles/332485.pdf
    Data publikacji:
    2016
    Wydawca:
    Polskie Towarzystwo Akustyczne
    Tematy:
    ray-tracing
    bistatic reverberation
    beam-forming
    Opis:
    A short-range experiment in shallow water has been performed to assess the various contributions to the impulse response. A sound source emitted pulses, centered at 25 kHz, that were registered by an array some 50 m away. The impulse response recordings show initial isolated peaks, followed by long decaying spiky tails. A 3-D ray model, Rev3D, was used to model the measured time traces. The initial peaks were identified as direct and multi-path propagation arrivals, while the decaying tails arise from bistatic reverberation involving the bottom and the sea surface in an elliptical area, with the source and receiver positions as focal points. Beam-forming with the receiver array was applied to locate the parts of the bottom with the most significant contributions to the impulse response, and to suggest an improved reflection-coefficient as well as scattering-kernel values. Rev3D modelling with energy-density maps for selected time intervals, and time traces for energy-weighted averages of various parameters, such as the arrival angles at the array, was also applied for this purpose.
    Źródło:
    Hydroacoustics; 2016, 19; 153-164
    1642-1817
    Pojawia się w:
    Hydroacoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Parallel implementation of ray tracing procedure in anisotropic medium
    Autorzy:
    Pieta, A.
    Dwornik, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/1933984.pdf
    Data publikacji:
    2012
    Wydawca:
    Politechnika Gdańska
    Tematy:
    ray tracing
    seismic anisotropy
    domain decomposition
    Opis:
    This article describes a parallel implementation of a ray tracing algorithm in a heterogeneous anisotropic geological medium. The shortest path method, which was used for calculations, can give ray path and travel time of seismic wave propagation even for a random and discontinuous velocity field. The high precision required in such calculations was obtained by employing a dense computational grid. This led to a significant increase in the computational effort of the algorithm. The procedure was parallelized using domain decomposition. The results show that the parallel performance of the ray tracing procedure strongly depends on the assumed geological method and differs between media with and without anisotropy of seismic wave propagation.
    Źródło:
    TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2012, 16, 1-2; 135-143
    1428-6394
    Pojawia się w:
    TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Vlasov Launcher Diagrammatic Design Using the RT Method
    Autorzy:
    Francik, Andrzej
    Jaworski, Grzegorz
    Nowak, Maciej
    Nowak, Kacper
    Powiązania:
    https://bibliotekanauki.pl/articles/1839339.pdf
    Data publikacji:
    2021
    Wydawca:
    Instytut Łączności - Państwowy Instytut Badawczy
    Tematy:
    gyrotron output
    ray tracing
    Vlasov launcher
    Opis:
    In this paper, a simple and fast method relied upon for designing a Vlasov launcher with a helical cut is proposed. The method is based on graphic interpretation of analytical relationships that link wave parameters (EM field mode) to the launcher’s geometrical dimensions. Using the ray tracing method, a simplified graphic analysis may be carried out. The results obtained are not significantly different from those of rigorous full-wave analyzes. The family of normalized curves that is created in the process greatly facilitates the stage of optimizing the geometrical parameters of the Vlasov launcher.
    Źródło:
    Journal of Telecommunications and Information Technology; 2021, 2; 57-67
    1509-4553
    1899-8852
    Pojawia się w:
    Journal of Telecommunications and Information Technology
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Research on a square Cassegrain-type solar concentrating reflector with a double pyramid
    Autorzy:
    Zhang, Y.
    Yang, H.
    Jiang, P.
    Mao, S.
    Yu, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/174264.pdf
    Data publikacji:
    2016
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    concentrating reflector
    double pyramidal
    ray tracing
    Opis:
    A structure of a solar concentrating reflector is designed in this paper to improve the usage of solar energy. For the dark image which is the result of the secondary mirror in the new type of the Cassegrain solar concentrating system, a double pyramid system is used to improve this phenomenon. By eliminating the dark image, the system enhanced the concentration ratio and the working efficiency. Meanwhile, both the primary and secondary mirrors are shaped into a square section in order to get a better match with a square photovoltaic receiver. While the length of the primary mirror is 89m and the block ratio is 20%, the concentration ratio is equal to 118.86.
    Źródło:
    Optica Applicata; 2016, 46, 3; 461-471
    0078-5466
    1899-7015
    Pojawia się w:
    Optica Applicata
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Propagation prediction for indoor wireless local area network application
    Autorzy:
    Sharoun, A. O.
    Artimei, E. E.
    Powiązania:
    https://bibliotekanauki.pl/articles/378307.pdf
    Data publikacji:
    2015
    Wydawca:
    Politechnika Poznańska. Wydawnictwo Politechniki Poznańskiej
    Tematy:
    indoor WLAN
    ray tracing by using
    VPL
    Opis:
    The application of wireless local area network (WLAN) is increasing in offices, it becomes important to study signal propagation indoor environment. In this Paper, the Site Ware Technologies` site specific propagation prediction tool is a Three-dimensional (3-D) ray tracing code employing modified shoot and bounce Ray (SBR) method known as the Vertical Plane Launch (VPL) is used to predict indoor propagation effects in a cultural Center. The simulation experiment is carried out to select the best location for installing a transmitter in a large center with many rooms and corridors. Receivers should available in all of the rooms. To understand how electromagnetic waves reach the receiver, visualization software was used based on Matlab. This type of simulation will save money by selecting the minimum power of a single transmitter and choosing the least number of transmitters in large buildings.
    Źródło:
    Poznan University of Technology Academic Journals. Electrical Engineering; 2015, 84; 85-91
    1897-0737
    Pojawia się w:
    Poznan University of Technology Academic Journals. Electrical Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Crustal structure of the Trans-European Suture Zone in Central Poland - reinterpretation of the LT-2, LT-4 and LT-5 deep seismic sounding profiles
    Autorzy:
    Grad, M.
    Guterch, A.
    Polkowska-Purys, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/2058903.pdf
    Data publikacji:
    2005
    Wydawca:
    Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
    Tematy:
    TESZ
    crustal structure
    seismic refraction
    ray tracing
    Opis:
    The paper gives a reinterpretation of data from three deep seismic sounding profiles-LT-2, LT-4 and LT-5 - acquired in 1974-1979 between the Precambrian East European Craton (EEC) and the Palaeozoic Platform (PP) in Central Poland. Good quality seismic records in the distance interval from 50-90 to 200-280 km were the input data for the modelling of the crustal and uppermost mantle structure. Clear first arrivals and later phases of waves reflected/refracted from the crustal and the Moho boundaries were interpreted using a two-dimensional (2-D) ray tracing technique. In general, the crustal thickness along the three profiles varies from 30-35 km in the Palaeozoic platform area, to 42-44 km in the Polish part of the EEC, being 35-40 km in the transition zone between the PP and the EEC. In the transition area, the P-wave velocity is very low (Vp < 6.0 km/s) down to depths of 15-18 km, indicating that a very thick succession of sedimentary, metamorphosed or volcanic origin rocks is present there. All three 2-D models of the crust are discussed together with results obtained 20-30 years ago, particularly taking into account the difference in interpretation methods and new computation possibilities. Jointly with recent seismic studies along the profiles LT-7 and TTZ, as well as the POLONAISE'97 profiles P1-P4, the reinterpreted old profiles provide a collection of crustal models of the TESZ in Poland.
    Źródło:
    Geological Quarterly; 2005, 49, 3; 243--252
    1641-7291
    Pojawia się w:
    Geological Quarterly
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    A skew ray tracing approach for error analysis of a light ray path for optical systems with asymmetrical optical axes
    Autorzy:
    Liao, T T
    Kung, C
    Chen, C T
    Powiązania:
    https://bibliotekanauki.pl/articles/173300.pdf
    Data publikacji:
    2015
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    skew ray tracing
    homogeneous coordinate transformation matrix
    error analysis
    Opis:
    This study applies a skew ray tracing approach based on a 4×4 homogeneous coordinate transformation matrix and Snell’s law to analyze the errors of a ray light path as it passes through a series of optical elements in an asymmetrical optical system. The proposed error analysis methodology considers two principal sources of a light path error, namely: i) the translational errors and the rotational errors which determine the deviation of the light path at each boundary surface, and ii) the differential changes induced in the incident point position and unit directional vector of the refracted/reflected ray as a result of differential changes in the position and unit directional vector of the light source. The validity of the proposed methodology is verified by analyzing the effects of optical errors in a corner cube.
    Źródło:
    Optica Applicata; 2015, 45, 2; 249-261
    0078-5466
    1899-7015
    Pojawia się w:
    Optica Applicata
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Modulation Mechanism of Acoustic Scattering in Underwater Corner Reflectors with Acoustic Metasurfaces
    Autorzy:
    Du, Jiaman
    Peng, Zilong
    Ge, Lili
    Lyu, Shijin
    Zhou, Fulin
    Liu, Yan
    Powiązania:
    https://bibliotekanauki.pl/articles/31339794.pdf
    Data publikacji:
    2023
    Wydawca:
    Polska Akademia Nauk. Czasopisma i Monografie PAN
    Tematy:
    acoustic scattering
    metasurface
    ray tracing
    corner reflector
    virtual source method
    Opis:
    Using the tunderwater corner reflector (CR) to simulate the acoustic scattering characteristics of the military target is a new technology to counter active sonar detection. Existing underwater CRs only have the ability to interfere with the acoustic field, but have limitations in acoustic wave modulation. Therefore, acoustic metasurfaces applied on CRs to enhance the ability of acoustic wave modulation has a great application prospect. A fast prediction method based on the Kirchhoff approximation (KA) and the ray tracing theory is proposed to calculate the acoustic scattering characteristics of CR with acoustic metasurfaces in grooves array type. The accuracy of the method is verified by the finite element method (FEM) simulation. The modulation effect of CR with grooves array in different gradient combinations on the structural scattering acoustic field is analyzed. The research shows that the CR with different combinations of the acoustic metasurface has an obvious modulation effect on the amplitude of the acoustic waves and the deflection of acoustic field. In particular, the grooves array in combination with positive and negative gradients has an obvious deflection impact on the scattering acoustic field.
    Źródło:
    Archives of Acoustics; 2023, 48, 4; 465-473
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Formation of Scattering Characteristics for Acoustical Ray Tracing Simulation
    Autorzy:
    Bojičić, S.
    Šumarac-Pavlović, D.
    Mijić, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/178159.pdf
    Data publikacji:
    2018
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    diffuse reflection
    ray tracing
    room acoustics
    secondary source
    scattering pattern
    Opis:
    Ray tracing simulation of sound field in rooms is a common tool in room acoustic design for predicting impulse response. There are numerous commercial engineering tools utilising ray tracing simulation. A specific problem in the simulation is the modelling of diffuse reflections when contribution of individual surface is prevailing. The paper introduces modelling of scattering which is interesting when the whole impulse response of a room is not a goal but contribution of certain surface. The main goal of the Project is to shape directivity characteristics of scattered reflection. Also, an innovative approach is suggested for converting the energy histogram information obtained by ray tracing into an “equivalent impulse response”. The proposed algorithm is tested by comparing the results with measurements in a real sound field, realised in a scaled model where a diffusing surface is hardware-implemented.
    Źródło:
    Archives of Acoustics; 2018, 43, 4; 657-667
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Evaluation of near field of the GSM base station antennas in urban environment
    Autorzy:
    Wójcik, D.
    Powiązania:
    https://bibliotekanauki.pl/articles/309235.pdf
    Data publikacji:
    2003
    Wydawca:
    Instytut Łączności - Państwowy Instytut Badawczy
    Tematy:
    dozymetria
    GSM
    RF dosimetries
    human exposure
    radio base station
    ray tracing
    Opis:
    A simple and efficient method for evaluation of near field of the GSM base station antennas in urban environment is presented in this paper. The method is based on the replacement of panel antenna with a discrete linear array. Moreover, the geometrical optics approach is used to consider the influence of environment. The approximate results are found to be in excellent agreement with the results obtained by using the method of moments (MoM). Presented method can be successfully used for fast evaluation of exposure to electromagnetic fields emitted by the GSM base station antennas in urban environment.
    Źródło:
    Journal of Telecommunications and Information Technology; 2003, 1; 41-44
    1509-4553
    1899-8852
    Pojawia się w:
    Journal of Telecommunications and Information Technology
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Design of external microtextures for efficient light outcoupling in OLEDs with different preferential orientation of emission dipoles
    Autorzy:
    Kovačič, Milan
    Powiązania:
    https://bibliotekanauki.pl/articles/2074200.pdf
    Data publikacji:
    2022
    Wydawca:
    Polska Akademia Nauk. Stowarzyszenie Elektryków Polskich
    Tematy:
    organic light-emitting diode
    light outcoupling
    dipole orientation
    ray tracing
    optical modelling
    Opis:
    External light outcoupling structures provide a cost-effective and highly efficient solution for light extraction in organic light-emitting diodes. Among them, different microtextures, mainly optimized for devices with isotopically oriented emission dipoles, have been proposed as an efficient light extraction solution. In the paper, the outcoupling for a preferential orientation of emission dipoles is studied for the case of a red bottom-emitting organic light-emitting diode. Optical simulations are used to analyse the preferential orientation of dipoles in combination with three different textures, namely hexagonal array of sine-textures, three-sided pyramids, and random pyramids. It is shown that while there are minimal differences between the optimized textures, the highest external quantum efficiency of 51% is predicted by using the three-sided pyramid texture. Further improvements, by employing highly oriented dipole sources, are examined. In this case, the results show that the top outcoupling efficiencies can be achieved with the same texture shape and size, regardless of the preferred orientation of the emission dipoles. Using an optimized three-sided pyramid in combination with ideally parallel oriented dipoles, an efficiency of 62% is achievable. A detailed analysis of the optical situation inside the glass substrate, dominating external light outcoupling, is presented. Depicted results and their analysis offer a simplified further research and development of external light extraction for organic light-emitting devices with highly oriented dipole emission sources.
    Źródło:
    Opto-Electronics Review; 2022, 30, 2; art. no. e141542
    1230-3402
    Pojawia się w:
    Opto-Electronics Review
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Lithospheric structure of the western part of the East European Craton investigated by deep seismic profiles
    Autorzy:
    Grad, M.
    Janik, T.
    Guterch, A.
    Środa, P.
    Czuba, W.
    Powiązania:
    https://bibliotekanauki.pl/articles/2058944.pdf
    Data publikacji:
    2006
    Wydawca:
    Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
    Tematy:
    East European Craton
    crustal structure
    mantle reflectors
    deep seismic refraction
    seismic ray tracing
    Opis:
    The Palaeoproterozoic collision of Archaean Fennoscandia, Volgo-Uralia and Sarmatia, viewed as a large composite of terranes, each with an independent history during Archaean and Early Proterozoic time, formed the East European Craton. This paper summarizes the results of deep seismic sounding investigations of the lithospheric structure of the southwestern part of the East European Craton. On the basis of the modern EUROBRIDGE’94–97, POLONAISE’97 and CELEBRATION 2000 projects, as well as of data from the Coast Profile and from reinterpreted profiles VIII and XXIV, the main tectonic units of Fennoscandia and Sarmatia are characterized. The crustal thickness in the whole area investigated is relatively uniform, being between 40 and 50 km (maximum about 55 km). For Fennoscandia, the crystalline crust of the craton can be generally divided into three parts, while in Sarmatia the transition between the middle and lower crust is smooth. For both areas, relatively high P-wave velocities ( 7.0 km/s) were observed in the lower crust. Relatively high seismic velocities of the sub-Moho mantle (~8.2–8.3 km/s) were observed along most of the profiles. The uppermost mantle reflectors often occur ca. 10 to 15 km below the Moho. Finally, we show the variability in physical properties for the major geological domains of Fennoscandia and Sarmatia, which were crossed by the network of our profiles.
    Źródło:
    Geological Quarterly; 2006, 50, 1; 9-22
    1641-7291
    Pojawia się w:
    Geological Quarterly
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Modelowanie trajektorii promieni i czasów przebiegu fal odbitych PP, SS i PS dla dyskretnego ośrodka poprzecznie izotropowego z nachyloną osią symetrii
    The modeling of ray trajectories and travel times of reflected PP, SS, and PS waves in the discrete transversely isotropic medium with tilted symmetry axis
    Autorzy:
    Kasina, Z.
    Powiązania:
    https://bibliotekanauki.pl/articles/183652.pdf
    Data publikacji:
    2009
    Wydawca:
    Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
    Tematy:
    anizotropia
    geofizyka
    metody sejsmiczne
    hodografy
    trasowanie promieni
    geophysics
    seismic methods
    anisotropy
    hodographs
    ray tracing
    Opis:
    In the presented paper the basic assumptions of the algorithm and program of seismic ray trajectories and travel times modelling are described for the case of reflected PP, SS and PS waves in the discrete anisotropic (transversely isotropic) medium with tilted symmetry axis. The ray trajectories and travel times in the discrete horizontally layered medium (VTI) and in the monoclinally dipping layers are defined by means of the numerical solution of the partial equations set resulting from the Fermat principle. The values of the velocities and Thomsen anisotropy parameters are defined in the nodes of the assumed, two dimensional grid. The comparison of the reflection waves hodographs was accomplished for selected isotropic and anisotropic models in the case of CDP gathers.
    Źródło:
    Geologia / Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie; 2009, 35, 2/1; 387-392
    0138-0974
    Pojawia się w:
    Geologia / Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Per-pixel extrusion mapping with correct silhouette
    Autorzy:
    Chahdi, Adnane Ouazzani
    Ragragui, Anouar
    Halli, Akram
    Satori, Khalid
    Powiązania:
    https://bibliotekanauki.pl/articles/2097961.pdf
    Data publikacji:
    2021
    Wydawca:
    Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
    Tematy:
    image-based rendering
    real-time rendering
    texture mapping
    per-pixel extrusion mapping
    ray-tracing
    silhouette
    Opis:
    Per-pixel extrusion mapping consists of creating a virtual geometry that is stored in a texture over a polygon model without increasing its density. There are four types of extrusion mapping; namely, basic extrusion, outward extru sion, beveled extrusion, and chamfered extrusion. These different techniques produce satisfactory results in the case of plane surfaces; however, when it is about curved surfaces, a silhouette is not visible at the edges of the extruded forms on the 3D surface geometry, as they not take the curvatures of the 3D meshes into account. In this paper, we present an improvement that consists of using curved ray-tracing to correct the silhouette problem by combining per-pixel extrusion-mapping techniques with a quadratic approximation that is computed at each vertex of a 3D mesh.
    Źródło:
    Computer Science; 2021, 22 (3); 403-428
    1508-2806
    2300-7036
    Pojawia się w:
    Computer Science
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Radary SuperDARN : narzędzie do badania i monitorowania atmosfery Ziemi i przestrzeni wokółziemskiej
    SuperDARN radars : a tool for testing and monitoring Earth’s atmosphere and near-earth space
    Autorzy:
    Góral, Grzegorz
    Powiązania:
    https://bibliotekanauki.pl/articles/163945.pdf
    Data publikacji:
    2019
    Wydawca:
    Polskie Towarzystwa Geofizyczne
    Tematy:
    International Reference Ionosphere
    jonosfera
    radar HF
    rozpraszanie koherentne
    ray tracing
    SuperDARN
    coherent scattering
    HF radar
    ionosphere
    Opis:
    Radary SuperDARN powstały jako narzędzie do badań górnych warstw atmosfery i ich związków z magnetosferą i wiatrem słonecznym (Greenwald i in. 1995; Chisham i in. 2007; Lester 2008, 2013). Pracują w zakresie częstotliwości HF, pomiędzy 8 a 20 MHz. Ich zasada działania opiera się na wykorzystaniu rozpraszania Bragga na periodycznych strukturach przestrzennych o skalach odległości porównywalnych z długością fali sondującej. Radary te umożliwiają obserwacje formacji jonosferycznych zorientowanych wzdłuż linii pola geomagnetycznego. W artykule opisano podstawowe bloki funkcjonalne przykładowego radaru SuperDARN: tor nadawczy, odbiorczy oraz system antenowy. Omówiony został sposób modelowania wiązki sondującej. Jedną z kluczowych kwestii przy wyborze lokalizacji dla nowopowstającej stacji SuperDARN jest określenie jej potencjalnych możliwości obserwacyjnych. Można wykorzystać do tego oprogramowanie dokonujące śledzenia dróg propagacji impulsu emitowanego przez radar i określania punktów, w których wektor fali jest prostopadły do lokalnego pola magnetycznego Ziemi. Warunek taki pozwoli na uzyskanie rozproszenia wyemitowanej przez antenę radaru fali z powrotem, w kierunku nadawania. W artykule przedstawiono wyniki symulacji dla hipotetycznej stacji SuperDARN, zlokalizowanej w południowo-zachodniej Polsce. W obliczeniach użyto programu do ray tracingu, bazującego na algorytmie Jones i Stephenson (1975) oraz modelu jonosfery IRI-2012.
    SuperDARN radars were developed as a tool for testing the upper atmosphere regions and their coupling with the magnetosphere and solar wind (Greenwald et al. 1995; Chisham et al. 2007; Lester 2008, 2013). They work in the HF frequency range, between 8 and 20MHz. Their principle of operation is based on the use of Bragg scattering on periodic spatial structures with scales of distance comparable to the length of the sounding wave. These radars allow observation of ionospheric formations oriented along the geomagnetic field lines. The article describes basic functional SuperDARN radar blocks: transmitting path, receiving path, and the antenna system as well. The method of modeling the sounding beam is also presented. One of the key issues when choosing a location for a new SuperDARN station is to determine its potential for observation. You can use a special software to track the propagation paths of the pulse emitted by the radar and determining points in which the wave vector is perpendicular to the local geomagnetic field. Such a condition will allow to obtain the scatter of the wave emitted by the radar antenna back into the direc¬tion of transmission. The article presents simulation results for a hypothetical SuperDARN station, located in south-western Poland. The calculation were based on a ray tracing program based on the Jones and Stephenson algorithm (Jones, Stephenson 1975) and the IRI-2012 ionosphere model.
    Źródło:
    Przegląd Geofizyczny; 2019, 3-4; 253-265
    0033-2135
    Pojawia się w:
    Przegląd Geofizyczny
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Modeling with seismic ray tracing in inhomogeneous geological formation
    Modelowanie sejsmiczne ośrodków niejednorodnych metodą "punkt strzałowy - punkt odbioru"
    Autorzy:
    Cygan, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/952728.pdf
    Data publikacji:
    2006
    Wydawca:
    Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
    Tematy:
    śledzenie promienia sejsmicznego
    kaustyki
    strefa cienia
    modelowanie sejsmiczne
    seismic ray tracing
    caustic points
    shadow zone
    seismic modeling
    Opis:
    Seismic ray tracing is an useful tool to solve the complicated problem of wave propagation. It makes possible obtaining essential information about wave propagation in geological media without necessity of computing the full wave field. In this paper the theoretical principle of seismic ray tracing has been presented. Moreover few typical models of inhomogeneous geological media have been taking into account. Ray tracing methods have been divided into several categories and shooting method has been particularly described. Using results of modeling realized with the SEISMIC UN*X system, advantages and possibilities of the practical application in seismic tomography have been shown.
    Śledzenie promienia sejsmicznego jest narzędziem do rozwiązywania złożonego zagadnienia propagacji fal. Pozwala uzyskać istotne informacje o rozchodzeniu się fal sejsmicznych w ośrodku geologicznym bez konieczności wyznaczania pełnego pola falowego. W artykule przedstawiono podstawy teoretyczne śledzenia promieni sejsmicznych w kilku wzorcowych modelach niejednorodnych ośrodków geologicznych. Szczególną uwagę zwrócono na modele ośrodków o stałym i o zmiennym gradiencie prędkości w warstwach. Szczegółowo opisano metodę "punkt strzałowy - punkt odbioru". Wykorzystując wyniki modelowania wykonanego za pomocą systemu SEISMIC UN*X, pokazano jego zalety oraz możliwości wykorzystania zarówno w sejsmice głębokiej, jak i płytkiej.
    Źródło:
    Geologia / Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie; 2006, 32, 4; 451-462
    0138-0974
    Pojawia się w:
    Geologia / Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Radiation heat transfer model using Monte Carlo ray tracing method on hierarchical ortho-Cartesian meshes and non-uniform rational basis spline surfaces for description of boundaries
    Autorzy:
    Kuczyński, P.
    Białecki, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/240072.pdf
    Data publikacji:
    2014
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    radiation heat transfer
    Monte Carlo
    ray tracing
    NURBS surfaces
    radiacyjna wymiana ciepła
    metoda śledzenia promieni
    powierzchnia NURBS
    Opis:
    The paper deals with a solution of radiation heat transfer problems in enclosures filled with nonparticipating medium using ray tracing on hierarchical ortho-Cartesian meshes. The idea behind the approach is that radiative heat transfer problems can be solved on much coarser grids than their counterparts from computational fluid dynamics (CFD). The resulting code is designed as an add-on to OpenFOAM, an open-source CFD program. Ortho-Cartesian mesh involving boundary elements is created based upon CFD mesh. Parametric non-uniform rational basis spline (NURBS) surfaces are used to define boundaries of the enclosure, allowing for dealing with domains of complex shapes. Algorithm for determining random, uniformly distributed locations of rays leaving NURBS surfaces is described. The paper presents results of test cases assuming gray diffusive walls. In the current version of the model the radiation is not absorbed within gases. However, the ultimate aim of the work is to upgrade the functionality of the model, to problems in absorbing, emitting and scattering medium projecting iteratively the results of radiative analysis on CFD mesh and CFD solution on radiative mesh.
    Źródło:
    Archives of Thermodynamics; 2014, 35, 2; 65-92
    1231-0956
    2083-6023
    Pojawia się w:
    Archives of Thermodynamics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Opracowanie symulatora echosondy wielowiązkowej
    Development of a simulator of multibeam echosounder
    Autorzy:
    Maleika, W.
    Pałczyński, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/209931.pdf
    Data publikacji:
    2011
    Wydawca:
    Wojskowa Akademia Techniczna im. Jarosława Dąbrowskiego
    Tematy:
    numeryczny model terenu (DTM)
    echosonda wielowiązkowa
    metoda śledzenia promieni
    digital terrain model (DTM)
    multibeam echosounder
    ray tracing
    Opis:
    W artykule uzasadniono potrzebę stworzenia programowego symulatora echosondy wielowiązkowej oraz symulowania wirtualnych sondaży morskich. Przedstawiono opracowany algorytm działania symulatora oraz wirtualnych pomiarów uwzględniających parametry ruchu jednostki oraz przetwornika. Zaproponowana metoda może być wartościowym narzędziem badawczym w obszarze metod tworzenia DTM oraz w optymalizacji rzeczywistych prac hydrograficznych.
    The paper deals with the process of building digital terrain model (DTM) of a seabed basing on multibeam echosounder data. One of the most difficult problems in this area is verification of existing interpolation methods using real data, since the exact shape of the bottom is uncertain. Authors propose introducing the simulation of the hydrographic survey over the high resolution DTM in order to obtain a set of virtual points which can be the source for creating terrain models using different interpolation methods. Such a procedure gives a powerful research tool due to the possibility of simple comparison of the resulting and source terrain models. The algorithm of virtual survey is based on the ray tracing method. Input data consist of the source DTM, description of vessel movement and the echosounder parameters. During each virtual ping, every beam is represented as a ray, which is traced according to sound wave propagation trajectory in order to find an intersection with the terrain model. The coordinates of intersection points are stored as the output of the method. Described algorithm was implemented and the first attempt of its verification is described in the paper. The basis of the research was the set of real data aquired by multibeam echosounder. The high resolution DTM was calculated, the vessel movement and echosounder parameters were obtained as well, then virtual survey was performed. The matter of the research was the spatial distribition of virtual survey points. The results show a similarity of distributions of real and simulated points, including the number of points, distances between them and a beam width. The method introduced in the paper can be powerful verification tool in the area of DTM calculation methods. It will be also useful for the research of the impact of hydrographic survey parameters on the accuracy of resulting digital terrain model.
    Źródło:
    Biuletyn Wojskowej Akademii Technicznej; 2011, 60, 3; 215-225
    1234-5865
    Pojawia się w:
    Biuletyn Wojskowej Akademii Technicznej
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Geometrical and optical analysis of small-sized parabolic trough collector using ray tracing tool SolTrace
    Autorzy:
    Singh, Raman Kumar
    Chandra, Prakash
    Powiązania:
    https://bibliotekanauki.pl/articles/27312206.pdf
    Data publikacji:
    2023
    Wydawca:
    Polska Akademia Nauk. Czasopisma i Monografie PAN
    Tematy:
    parabolic trough collector
    SolTrace
    Monte Carlo ray tracing method
    nonuniform heat flux distribution
    optical analysis
    geometrical analysis
    Opis:
    The present work is aimed at geometrical optimization and optical analysis of a small-sized parabolic trough collector (PTC). Improving the performance of parabolic trough collectors can greatly justify the use of solar energy. An optimized curvature geometry, the location of the absorber tube, and the heat flux distribution along the circumference of the absorber tube are major features in the geometric optimization and optical modelling of parabolic trough collectors. Rim angle, aperture width, the diameter of the absorber tube, receiver position, and the optimum value of heat flux are the major parameters considered in this work for geometrical and optical analysis. The Monte Carlo ray tracing method has been adopted for analysis. The non-uniform heat flux distribution profile obtained from optical analysis of the proposed parabolic trough collector has been compared with the profile available in the literature, and good agreement has been obtained, which proves the feasibility and reliability of the model and method used for this study. An experimental new small-sized parabolic trough collector has been fabricated for the optimized rim angle of 90 deg after a successful laser light feasibility test. The effect of the absorber tube position along the optical axis on the heat flux profile was analysed and found to be substantial. Furthermore, the sensitivity analysis of the parabolic trough collector using the software applied has been discussed separately.
    Źródło:
    Archives of Thermodynamics; 2023, 44, 3; 35--61
    1231-0956
    2083-6023
    Pojawia się w:
    Archives of Thermodynamics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
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