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Distribution of Emerged Energy for Daylight Illuminate on Prismatic Elements

JOURNAL OF SOLAR ENERGY ENGINEERING-TRANSACTIONS OF THE ASME 2011年第2期133卷 21007.1-21007.9页

作者： Yeh, Shih-Chuan Whang, Allen Jong-Woei Hsiao, Horng-Ching Hu, Xi-Duo Chen, Yi-Yung Natl Taiwan Univ Sci & Technol De Lin Inst Technol Tucheng City 236 Taipei County Taiwan Natl Taiwan Univ Sci & Technol Taipei 10607 Taiwan Dongguan Univ Technol Dongguan 523808 Guangdong Peoples R China

Prismatic elements are typical devices of natural light illumination system for redirecting and collecting daylight. Based on the principles of optics, this paper presents a simple mathematical matrix ray-tracing methodology through which a detailed intensity distribution of parallel light beam incident onto a right angled prism from different incident angles can be calculated precisely. We also present the distribution of the secondary emerged intensity from a prism illuminated by the emerged light of an adjacent prism. The direction, concentration, and distribution of intensity of the emerged light from the parallel light incident onto a surface of the right-angle prism, as well as daylight illuminate on a prismatic collector, are precisely calculated. The detailed calculation of the emerged light re-incident onto the adjacent prism or emerged out of the prismatic element presented that most of daylight are directly emerged out and are confined in some directions at earlier morning and afternoon, and the emerged light re-incident into the adjacent prism at noon around. This detailed calculation model of parallel light beam incident to a prismatic element can be applied to the hybrid natural light illumination system, as well as to the prism-relative solar illumination system for the improvement of efficiency. [DOI: 10.1115/1.4003587]

关键词： SPECTRAL energy distribution PRISMS BEAM splitters MATHEMATICAL analysis ray tracing algorithms OPTICS DAYLIGHT

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Interactive vizualization of constructive solid geometry scenes on graphic processors

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PROGRAMMING AND COMPUTER SOFTWARE 2017年第4期43卷 258-267页

作者： Ulyanov, D. Bogolepov, D. Turlapov, V. Lobachevskii State Univ Pr Gagarina 23 Nizhnii Novgorod 603950 Russia OPEN CASCADE SAS 1 Pl Frures Montgolfier F-78280 Guyancourt France

A ray-tracing algorithm for interactive visualization of very large and structurally complicated scenes presented in the constructive solid geometry (CSG) form is suggested. The algorithm is capable of visualizing such scenes in real time by using a graphic processor. As primitives, classical shapes and objects represented in an analytical form (in particular, second-order surfaces and implicit functions) are used. Unlike other similar algorithms, our algorithm produces the final image in a single pass and has no constraints on the maximum number of primitives and on the CSG tree depth. The key feature of the algorithm is a method for optimizing CSG models, which converts the input tree to an equivalent spatially coherent and well-balanced form (a completely balanced equivalent tree may not exist). The performance of visualization after applying the optimization technique is shown to depend on only the computational resource of the GPU (in contrast to multi-pass algorithms whose performance is restricted by memory capacity). It has been shown experimentally that our algorithm is capable of rendering CSG models consisting of more than a million CSG primitives with the tree depth up to 24.

关键词： COMPUTER visualization GRAPHICS processing units (Computers) ray tracing algorithms SOLID geometry MICROPROCESSORS

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Contribution of posterior corneal astigmatism to total corneal astigmatism

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JOURNAL OF CATARACT AND REFRACTIVE SURGERY 2012年第12期38卷 2080-2087页

作者： Koch, Douglas D. Ali, Shazia F. Weikert, Mitchell P. Shirayama, Mariko Jenkins, Richard Wang, Li Baylor Coll Med Dept Ophthalmol Cullen Eye Inst Houston TX 77030 USA

PURPOSE: To determine the contribution of posterior corneal astigmatism to total corneal astigmatism and the error in estimating total corneal astigmatism from anterior corneal measurements only using a dual-Scheimpflug analyzer. SETTING: Cullen Eye Institute, Baylor College of Medicine, Houston, Texas, USA. DESIGN: Case series. METHODS: Total corneal astigmatism was calculated using ray tracing, corneal astigmatism from simulated keratometry, anterior corneal astigmatism, and posterior corneal astigmatism, and the changes with age were analyzed. Vector analysis was used to assess the error produced by estimating total corneal astigmatism from anterior corneal measurements only. RESULTS: The study analyzed 715 corneas of 435 consecutive patients. The mean magnitude of posterior corneal astigmatism was -0.30 diopter (D). The steep corneal meridian was aligned vertically (60 to 120 degrees) in 51.9% of eyes for the anterior surface and in 86.6% for the posterior surface. With increasing age, the steep anterior corneal meridian tended to change from vertical to horizontal, while the steep posterior corneal meridian did not change. The magnitudes of anterior and posterior corneal astigmatism were correlated when the steeper anterior meridian was aligned vertically but not when it was aligned horizontally. Anterior corneal measurements underestimated total corneal astigmatism by 0.22 @ 180 and exceeded 0.50 D in 5% of eyes. CONCLUSIONS: Ignoring posterior corneal astigmatism may yield incorrect estimation of total corneal astigmatism. Selecting toric intraocular lenses based on anterior corneal measurements could lead to overcorrection in eyes that have with-the-rule astigmatism and undercorrection in eyes that have against-the-rule astigmatism. Financial Disclosure: The authors received research support from Ziemer Group. In addition, Dr. Koch has a financial interest with Alcon Laboratories, Inc., Abbott Medical Optics, Inc., Calhoun Vision, Inc., Nu Lens, and Optimedi

关键词： ASTIGMATISM CORNEA -- Diseases ray tracing algorithms EYE -- Examination INTRAOCULAR lenses EYE -- Refractive errors

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Model of accommodation: Contributions of lens geometry and mechanical properties to the development of presbyopia

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JOURNAL OF CATARACT AND REFRACTIVE SURGERY 2010年第11期36卷 1960-1971页

作者： Van de Sompel, Dominique Kunkel, Gary J. Hersh, Peter S. Smits, Alexander J. Princeton Univ Dept Mech & Aerosp Engn Princeton NJ 08544 USA Univ Med & Dent New Jersey Inst Ophthalmol & Visual Sci Newark NJ 07103 USA

PURPOSE To determine the relative importance of lens geometry and mechanical properties for the mechanics of accommodation and the role of these elements in the causes and potential correction of presbyopia SETTING Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey, USA DESIGN Experimental study METHODS Finite element methods and ray-tracing algorithms were used to model the deformation and optical power of the human crystalline lens during accommodation The mechanical model treats the lens as an axisymmetric object, and the optical model incorporates a gradient refractive index Using these models the accommodation of a broad range of lenses with different geometries and mechanical properties were investigated RESULTS The most significant result was that reshaping the 45-year-old lens to the geometry of the 29-year-old lens while retaining the mechanical properties, restored the former s accommodation amplitude to 72% to 94% of that of the 29-year-old lens, depending on ciliary body displacement That is, reshaping can add 1 8 to 3 7 diopters of accommodation A sensitivity analysis showed that this result was robust over a wide range of mechanical and geometrical properties CONCLUSION The study results suggest that a significant amount of the loss of accommodation is due to changes in lens geometry

关键词： PRESBYOPIA FINITE element method CRYSTALLINE lens ray tracing algorithms REFRACTIVE index SENSITIVITY analysis OUTCOME assessment (Medical care)

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Concept for accelerated ray-based monostatic RCS simulations using bistatic approximations

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ADVANCES IN RADIO SCIENCE 2009年 7卷 29-35页

作者： Buddendick, H. Eibert, T. F. Univ Stuttgart Inst Radio Frequency Technol D-70550 Stuttgart Germany Tech Univ Munich Lehrstuhl Hochfrequenztech D-80290 Munich Germany

An approach enabling accelerated shooting and bouncing rays (SBR) simulations to determine the backscattering properties of electrically large and complex objects is presented. Instead of performing independent simulations for all required aspect angles, the concept is based on the idea of additionally exploiting bistatic information for some neighboring aspect angles. Therefore the results of the geometrical ray tracing, which consumes a large part of the computational resources in case of complex shaped objects can be reused multiple times with only low additional computational resources. This method works well for objects with a sufficiently smooth shape and if a large number of aspect angles is to be simulated. A simple generic simulation example is used to show the general applicability of the method and to examine the degradation of the results depending on the applied bistatic angle. Furthermore, the acceleration that can be expected by the presented approach is determined and verified with the simulation example.

关键词： BACKSCATTERING BISTATIC radar ray tracing algorithms SIMULATION methods & models RADAR

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Accuracy of corneal power measurements by a new Scheimpflug camera combined with Placido-disk corneal topography for intraocular lens power calculation in unoperated eyes

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JOURNAL OF CATARACT AND REFRACTIVE SURGERY 2012年第5期38卷 787-792页

作者： Savini, Giacomo Barboni, Piero Carbonelli, Michele Hoffer, Kenneth J. GB Bietti Eye Fdn IRCCS Rome Italy Studio Oculist Azeglio Bologna Italy Univ Calif Los Angeles Jules Stein Eye Inst Los Angeles CA 90024 USA St Marys Eye Ctr Santa Monica CA USA

PURPOSE: To assess the accuracy of the corneal power measurements with a new Scheimpflug camera combined with Placido-disk corneal topography (Sirius) (combined Scheimpflug camera-topographer) for intraocular lens (IOL) power calculation in unoperated eyes and compare the results with those by a validated corneal topographer (Keratron) (validated topographer). SETTING: Private practice. DESIGN: Case series. METHODS: Consecutive patients having phacoemulsification and in-the-bag IOL implantation were studied. Intraocular lens power was calculated using the Hoffer Q, Holladay 1, and SRK/T formulas;the axial length, as measured by ultrasound immersion biometry;and 3 corneal power measurements: validated topographer simulated keratometry (K);combined Scheimpflug camera-topographer simulated K (derived from anterior corneal curvature only);combined Scheimpflug camera-topographer mean pupil power (derived from anterior and posterior corneal curvatures through ray tracing). The prediction error was calculated as the difference between the predicted refraction and the refraction measured 1 month postoperatively. RESULTS: When the corneal power measurements from the combined Scheimpflug camera-topographer were used, the mean absolute error (MAE) ranged between 0.23 diopter (D) +/- 0.24 (SD) (simulated K and Hoffer Q formula) and 0.33 +/- 0.23 D (mean pupil power and SRK/T formula). There were no statistically significant differences between the MAE generated by the simulated Ks of the 2 devices with any of the 3 formulas. CONCLUSION: Both corneal power measurements (simulated K and mean pupil power) provided by the new combined Scheimpflug camera-topographer were successfully entered into third-generation IOL power calculation formulas in unoperated eyes.

关键词： CORNEAL topography INTRAOCULAR lenses CAMERAS PHACOEMULSIFICATION BIOMETRY ray tracing algorithms

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The appearance of the objects rolling at relativistic speeds

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CANADIAN JOURNAL OF PHYSICS 2008年第12期86卷 1437-1441页

作者： Sfarti, Adrian 20035 Northwind Sq Cupertino CA 95014 USA

In the late 1950s Terrell and Penrose produced a series of papers dealing with the appearance of the rapidly moving bodies while in rectilinear motion as photographed by a simple, pinhole camera. A few more articles on the same subject followed, for example, Penrose showed that a sphere is always seen having an exactly circular outline, at any velocity, at any distance and for any line of sight. In the present paper, we will deal with a more complex type of motion, the combination of translation and rotation that can be seen when observing the wheels of a vehicle passing by. Since Terrell and Penrose wrote their papers, great advances in the camera simulation via computer representation have been made. The field that deals with the simulation of realistic cameras via computers is called ray tracing. In the current paper, we will combine two different disciplines, relativistic physics and three-dimensional graphics to derive new results. Our paper is divided in two main parts, in the first half, we will derive the relativistic equations for rolling motion without slip and we will make some connections with the physical requirements of a relativistic ray-tracing algorithm. In the second half, we will review the foundations of classical ray-tracing algorithms and we will introduce the additional features for operation at relativistic speeds. We will demonstrate an interesting self-canceling effect of the relativistic Doppler shift on the colors wavelengths of the moving object.

关键词： RELATIVISTIC mechanics SPEED SPHERE ROTATIONAL motion DOPPLER effect TRANSLATIONAL motion ray tracing algorithms

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THE VISUAL SYSTEM AND PALEOECOLOGY OF THE SILURIAN OSTRACOD PRIMITIOPSIS PLANIFRONS

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JOURNAL OF PALEONTOLOGY 2009年第3期83卷 414-421页

作者： Tanaka, Gengo Siveter, David J. Parker, Andrew R. Gunma Museum Natl Hist Gunma 3702345 Japan Univ Leicester Dept Geol Leicester LE1 7RH Leics England Nat Hist Museum Dept Zool London SW7 5BD England Univ Sydney Dept Biol Sci Sydney NSW 2006 Australia

Here we report the first detailed reconstruction of the eye and visual system of a Paleozoic ostracod, namely the dimorphic primitiopsid (Palaeocopa) Primitiopsis planifrons Jones,. 1887. Evidence from the cuticular lens morphology and its position on the valve suggests that P. planifrons had a naupliar eye, which is the most common optical system in crustaceans. The characters of the eye, such as the separated cuticular lens on each valve and the strongly calcified nature of the lens and its diameter, are concordant with that of some Recent podocopid ostracods in which a divided type of naupliar eye is present. ray tracing of the reconstructed cuticular lens of the primitiopsid species demonstrates strong spherical aberration and a very long focal length (as in the eye of podocopids), which implies the presence of a spherical mirror (tapetum) below the lens. Study of the ontogenetic change of the valve thickness aids the suggestion that P. planifrons was nektobenthic. The size of its cuticular lens in relation to that of living podocopid ostracods, and the water depth at which these Recent forms occur, indicates that P. planifrons may have lived in a relatively shallow, well lit environment such as the deep subtidal zone. These interpretations are consistent with supposed paleoenvironmental conditions derived from geological evidence. Thus, analysis of the nature and relative size of the eye gives an independent test to help identify paleoenvironmental parameters of long extinct ostracods.

关键词： EYE PALEOECOLOGY STRATIGRAPHIC geology -- Silurian STRATIGRAPHIC geology -- Paleozoic ray tracing algorithms PODOCOPIDA

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The customized reflections of freeform mirrors

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PHYSICS TODAY 2010年第10期63卷 72-73页

作者： Hicks, R. Andrew Drexel Univ Philadelphia PA 19104 USA

The article discusses the techniques of using ray tracing to guide the construction of freeform mirrors which can be applied to a variety of problems. The U.S. Defense Advanced Research Projects Agency has designed pinhole camera which allows the light to enter through single point to project three-dimensional image plane. Based on mathematical analysis, the images produced in a camera is distorted if a curved mirror intervenes between object and hole.

关键词： LIGHT -- Scattering THREE-dimensional imaging PINHOLE cameras ray tracing algorithms MATHEMATICAL analysis

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Ultraviolet irradiance measurement and modeling for evaluating the effectiveness of in-duct ultraviolet germicidal irradiation devices

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HVAC&R RESEARCH 2012年第4期18卷 626-642页

作者： Lau, Josephine Bahnfleth, William Mistrick, Richard Kompare, Diana Univ Nebraska Lincoln Durham Sch Architectural Engn & Construct Omaha NE USA Penn State Univ Dept Architectural Engn Indoor Environm Ctr University Pk PA 16802 USA

This study uses ray-tracing software to calculate the fluence distribution in ultraviolet germicidal irradiation devices with different surface reflectivities and lamp configurations. Of five validation cases considered, one incorporating anisotropic duct surface reflectivity and wind-chill correction of lamp output gave the best agreement with planar irradiance measurements (mean error -3%, standard deviation 9%). The ray-tracing software was used as a validated design tool to evaluate two typical in-duct ultraviolet germicidal irradiation devices (Cases 6 and 7). Four identical UVC lamps were modeled inside a rectangular duct. The lamps were either arranged in parallel or cross flow, and spherical irradiance values along the flow path were compared. Without accounting for the thermal effect on lamp output, an ultraviolet germicidal irradiation device placed in a cross flow would give a higher average UV irradiance. This benefit would be practical when a sufficient straight run is provided in a ventilation system. However, a lamp in parallel flow would produce a more uniform UV irradiance field near the center of the device. Changing the thermal conditions would have significant impact on lamp outputs. Arranging lamps in a parallel flow would provide a higher total irradiance at low temperature and high flow conditions, especially for lamps with outputs lower than the simulated lamps and lamps without sleeves.

关键词： ULTRAVIOLET radiation IRRADIATION LAMPS ray tracing algorithms GEOMETRICAL optics ANALYSIS of variance LOW temperature (Weather)

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