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PL
W pracy przedstawiono analizę tłumienia ścieżki wyznaczoną w dokładnym modelu śledzenia wiązki dla pasma 28 GHz w scenariuszu Urban Micro. W tym celu przedstawiono sposób modelowania propagacji radiowej oraz opisano parametry środowiska radiowego. Badania symulacyjne przeprowadzono na przykładzie centrum miasta Poznania w środowisku Altair WinProp. Porównano wartości mocy odbieranej dla różnych wariantów modeli deterministycznych dla LOS i NLOS. Wyniki symulacji odniesiono do wyników pomiarowych.
EN
In this work signal path loss is analysed in precise ray tracing method for 28 GHz and Urban Micro scenario. To this aim, wireless propagation modelling is described and parameters of considered environment are given. Simulations are conducted in Altair WinProp software for area of city of Poznań. In the results, received power is investigated in LOS and NLOS cases. Simulation results are then compared with measurements.
PL
W prezentowanym artykule omówiono elementy wpływające na wydajność systemu lokalizacji w budynkach wykorzystującego technikę Bluetooth do nawigacji. Przedstawiono wyniki badania wpływu rozdzielczości map referencyjnych rozkładu mocy odebranej na dokładność wyznaczania lokalizacji. Przedstawiono zależność między rozdzielczością map, czasem przetwarzania i dokładnością algorytmów pozycjonowania. Wyniki wskazują, że staranny dobór rozdzielczości mapy może spowodować znaczne skrócenie czasu obliczeń przy jednoczesnym zachowaniu dokładności systemu pozycjonowania.
EN
The presented article discusses the elements affecting the efficiency of the location system in buildings using Bluetooth technology for indoor navigation. The results of the research on the impact of the resolution of received reference RSSI maps on the accuracy of the location determination are presented. The relationship between map resolution, processing time and the accuracy of positioning algorithms is showed. The results indicate that adequate selection of the map resolution can achieve a significant reduction of computation time while maintaining the accuracy of the positioning system.
PL
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.
EN
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.
EN
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.
5
Content available remote Point cloud based viewshed generation in AutoCad Civil 3D
EN
We propose a new method for a point cloud based viewshed generation. We start with a brief summary of existing methods for viewshed generation and then present ours based on point clouds. The method is implemented in AutoCAD Civil 3D. Moreover, we present an idea of how to deal with huge point clouds using AutoCAD Civil 3D and how to automatize this process.
PL
W artykule została przedstawiona metoda tworzenia wykresu widoczności na podstawie chmury punktów. Zaprezentowano zarówno znane dotychczas metody wyznaczania wykresów widoczności jak i metodę bazującą na chmurze punktów zaimplementowaną w oprogramowaniu AutoCAD Civil 3D. Omówiono również nowe rozwiązanie problemu przetwarzania dużej chmury punktów za pomocą programu AutoCAD Civil 3D oraz propozycję automatyzacji tego procesu.
PL
W artykule przedstawiono algorytm lokalizacji pasywnej oparty o system ultra szerokopasmowy. Proponowany algorytm na podstawie zmian w transmitancji kanału radiowego wprowadzonych przez lokalizowany obiekt zwraca położenie obiektu. Dla poruszającego się obiektu zaimplementowano filtr Kalmana. Na podstawie przeprowadzonych badań pokazano, że za pomocą proponowanego algorytmu można osiągnąć dokładność lokalizacji pojedynczego obiektu wynoszącą ok 0,4 m.
EN
In this paper a passive localization algorithm based on ultra-wideband system has been introduced. Proposed algorithm based on changes in channel impulse response introduced by localized object returns its position. For moving object Kalman filter has been implemented. Results of conducted measurements show that by using proposed algorithm localization error of 0,4 m. for single object tracking is achievable.
EN
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.
EN
The interpretation of seismic refraction and wide angle reflection data usually involves the creation of a velocity model based on an inverse or forward modelling of the travel times of crustal and mantle phases using the ray theory approach. The modelling codes differ in terms of model parameterization, data used for modelling, regularization of the result, etc. It is helpful to know the capabilities, advantages and limitations of the code used compared to others. This work compares some popular 2D seismic modelling codes using the dataset collected along the seismic wide-angle profile DOBRE-4, where quite peculiar/uncommon reflected phases were observed in the wavefield. The ~505 km long profile was realized in southern Ukraine in 2009, using 13 shot points and 230 recording stations. Double PMP phases with a different reduced time (7.5-11 s) and a different apparent velocity, intersecting each other, are observed in the seismic wavefield. This is the most striking feature of the data. They are interpreted as reflections from strongly dipping Moho segments with an opposite dip. Two steps were used for the modelling. In the previous work by Starostenko et al. (2013), the trial-and-error forward model based on refracted and reflected phases (SEIS83 code) was published. The interesting feature is the high-amplitude (8-17 km) variability of the Moho depth in the form of downward and upward bends. This model is compared with results from other seismic inversion methods: the first arrivals tomography package FAST based on first arrivals; the JIVE3D code, which can also use later refracted arrivals and reflections; and the forward and inversion code RAYINVR using both refracted and reflected phases. Modelling with all the codes tested showed substantial variability of the Moho depth along the DOBRE-4 profile. However, SEIS83 and RAYINVR packages seem to give the most coincident results.
9
Content available remote Modelowanie propagacji fal elektromagnetycznych metodą ray-tracingu
PL
Artykuł dotyczy problemów związanych z modelowaniem propagacji fal elektromagnetycznych w komorach bezodbiciowych. Omówiono modelowanie propagacji fal elektromagnetycznych przy pomocy metody śledzenia promieni. Przedstawiono zależności analityczne wykorzystywane w metodzie śledzenia promieni oraz algorytm programu komputerowego bazujący na powyższych zależnościach. Opisano program komputerowy bazujący na opisanym algorytmie. Przedstawiono wyniki walidacji opracowanego oprogramowania.
EN
The article concerns problems of electromagnetic wave propagation in semi-anechoic chambers. Electromagnetic wave propagation modelling using ray-tracing methodology is described. The analytical equations which are used in ray-tracing methodology are presented. The elaborated program algorithm basing on presented analytical equations is described. The worked out software application basing on the described algorithm is presented. The validation results of elaborated software are presented too.
EN
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.
11
Content available remote Parallel Implementation of Ray Tracing Procedure in Anisotropic Medium
EN
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.
12
Content available Opracowanie symulatora echosondy wielowiązkowej
PL
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.
EN
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.
EN
In the article the selected methods of modeling radiative energy transfer in participating media were compared. Calculations were performed for furnace chamber filled an absorbing-emmiting gas. Accuracy and duration of calculations using different methods were compared.
14
Content available remote The contact and immersion ultrasound methods compared using the ray tracing method
EN
The goal of this article was to compare the contact and immersion ultrasound methods using simulated data. The pursued changes were interrelated with both the axial length of the eye and with partial biometry parameters. The results were compared with empirical data from real eye samples. The main analysing method was a modified algorithm for the ray tracing method created in the DELPHI programming environment (Borland Enterprise). The sample included 129 eyes (64% women and 36% men) of average age 73.65 (SD 9.33) scheduled for surgical removal of cataract. The average axial length was 23.12 mm (SD 1.31). The methods were compared using the simulated movement of the probe from central and coincident positions. We confirmed the tendency of the contact method to register more scattered beam which provides distorted biometric data from the periphery. This was verified by the real data analysis. The average axial length of the eye was 23.12 mm (SD 1.315), measured by the contact method and 23.26 mm (SD 1.298), measured by the immersion method. The difference between the methods was 0.145 mm. The most important changes occur in the vitreum depth which correlated with the total axial length (r = 0.89). The ray tracing method provided evidence of greater accuracy of the immersion method which was more sensitive to probe displacement and provided more accurate data. The axial length of the eye was longer according to the immersion method but this had only secondary influence on the accuracy of the method. Applanation of the cornea is the primary source of the contact method inaccuracy. The vitreum depth was the most influenced.
PL
W artykule przedstawiono wyniki badań dotyczących obliczania krzywej profilowej zwierciadlanego odbłyśnika o symetrii obrotowej, która zapewni uzyskanie ustalonych parametrów fotometrycznych. Wykonano obliczenia z zastosowaniem numerycznych metod optymalizacji.
EN
There are presented research results that concern of calculation of luminaires. Researches have been done for mirror reflector profile of surface of revolution. The numerical optimization methods were used to find reflector profile for given photometric parameters.
16
Content available remote Grafika komputerowa - pomiędzy techniką świetlną a informatyką
PL
Przedstawiono fizyczne podstawy metod grafiki komputerowej oraz metod techniki świetlnej. Dokonano przeglądu najczęstszych metod obliczeniowych stosowanych w technice świetlnej oraz metod i algorytmów symulacyjnych używanych w technice świetlnej i grafice komputerowej.
EN
Physical background of computer graphics methods and lightning engineering methods were described. The review of most popular methods of calculation in lighting engineering and methods and algorithms used in lightning engineering and computer graphics was presented.
EN
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.
PL
Praca przedstawia geometryczne problemy, jakie występują przy zastosowaniu metody śledzenia promieni do wyznaczania figury jasnych punktów (FJP) reflektora. Zastosowanie współrzędnych jednorodnych znormalizowanych do opisu położenia elementów składowych reflektora pozwala uprościć obliczenia i jednocześnie uniknąć błędów numerycznych. Z drugiej strony ułatwia to również użycie metod przyspieszających obliczenia. Zastosowanie odpowiedniego opisu geometrii reflektora wpływa na poprawę efektywności wyznaczania FJP.
EN
This paper presents geometric problems that occur in implementation of the ray tracing method to the light point figure of a headlight simulation. The usage of normalized homogeneous coordinate system in position description of the headlight elements allows simplifying calculation and avoiding numerical errors as well. From the other hand it facilitates also usage of the accelerating methods. The proper geometric description of the headlight influences on the efficiency improvement of the light point figure determining.
19
Content available remote Virtual multibeam echosounder in investigations on sea bottom modeling
EN
The article presents problems of verifying DTM creating methods on the basis of real sounding data. There has been presented a concept of solving these problems by applying virtual hydrostatic sounding. A method has been worked out of simulating a single and multibeam echosounder taking into account vessel movement and transducer parameters. Elements of ray tracing have been used in the algorithm. The method proposed may be a valuable research tool in methods of creating DTM and in planning real marine soundings.
20
Content available remote Modelowanie odbicia od powierzchni metalu z wykorzystaniem funkcji BRDF
PL
Do modelowania odbicia światła powszechnie jest używana funkcja rozkładu współczynnika odbicia dwukierunkowego (BRDF). Symulacja figury jasnych punktów wymaga modelowania odbicia światła od powierzchni metalu. Artykuł prezentuje przegląd najważniejszych modeli odbicia i ich właściwości. Rozpatrywane są modele He-Torrance'a-Silliona-Greenberga, Cooka-Torrance'a, Embrechtsa, Ashikhmina-Shirleya, Phonga i Warda. Analiza pozwala wybrać najbardziej przydatny model do symulacji figury jasnych punktów.
EN
BRDF is commonly used for modeling the reflection of light. Simulation of the light point figure requires modeling the reflection from the metallic surface. The paper presents review of the most important BRDF models and their features. He-Torrance-Sillion-Greenberg, Cook-Torrance, Embrechts, Ashikhmin-Shirley, Phong and Ward function are considered. The most useful model in a light point figure simulation is selected.
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