DEFINITION AND DETERMINATION OF THE BEAM AXIS AND BEAM ANGLE OF COMPLEX LUMINOUS INTENSITY DISTRIBUTIONS

2018 ◽  
Author(s):  
Tony Bergen ◽  
Peter Blattner
Keyword(s):  
Beam Axis ◽  
Luminous Intensity ◽  
Beam Angle

scholarly journals Luminous Intensity Field Optimization for Antiglare LED Desk Lamp without Second Optical Element

2020 ◽  
Vol 10 (7) ◽  
pp. 2607 ◽  
Author(s):  
Zhi-Ting Ye ◽  
Chieh Chang ◽  
Mao-Chieh Juan ◽  
Kuei-Jung Chen
Keyword(s):  
Light Emitting Diode ◽  
Optical Element ◽  
Spatial Effect ◽  
Experimental Results ◽  
Luminous Intensity ◽  
Beam Angle ◽  
Intensity Curve ◽  
Light Emitting ◽  
Human Eye ◽  
Intensity Field

This study proposes a model of a light module with an optimized luminous intensity field for realizing an antiglare light-emitting diode (LED) desk lamp without a second optical element. We simulated different luminous intensity field profiles to analyze the unified glare rating (UGR) and illumination uniformity performance of a desk lamp. The spatial effect of UGR and the illumination uniformity affect eye comfort. The light module was set to different beam angles without a second optical element, louver structure, and reflective element on the luminaire to compare different UGRs and uniformity values for evaluating human eye comfort. The simulation and experimental results indicated that the luminous intensity curve for a beam angle of 90° achieved an illumination uniformity of 80% and a UGR of 18.1 at a height of 45 cm, thus realizing a human-friendly antiglare desk lamp.

scholarly journals Lung IMRT planning with automatic determination of beam angle configurations

2018 ◽  
Vol 63 (13) ◽  
pp. 135024 ◽  
Author(s):  
Lulin Yuan ◽  
Wei Zhu ◽  
Yaorong Ge ◽  
Yuliang Jiang ◽  
Yang Sheng ◽  
...  
Keyword(s):  
Beam Angle ◽  
Automatic Determination ◽  
Imrt Planning

scholarly journals Extended versus point light source: where does the difference in the illuminance exist?

2021 ◽  
Vol 18 (1) ◽  
pp. 127
Author(s):  
V. Ivchenko
Keyword(s):  
Light Source ◽  
Undergraduate Students ◽  
General Position ◽  
Observation Point ◽  
Luminous Intensity ◽  
Reasonable Accuracy ◽  
Point Light Source ◽  
The Difference ◽  
Point Light

In this paper we derive and analyse the expressions to find the illuminance from luminous ball, disc and line in the case of general position of the light receiver. We show that one can always replace a luminous ball with a point light source located at its center and having the appropriate luminous intensity. Any luminous disc or line can be considered, with reasonable accuracy (the relative error in the determination of the illuminance is less than $5 \%$), as the point light source with anisotropic (cosine) luminous intensity and placed at their center, if the distance to the observation point is approximately four times larger than their characteristic sizes. The issues outlined in this article will be useful for undergraduate students, who study the basics of photometry.

Galactic orbits of stars

1966 ◽  
Vol 25 ◽  
pp. 93-97
Author(s):  
Richard Woolley
Keyword(s):  
Globular Cluster ◽  
Potential Field ◽  
High Velocity ◽  
Velocity Vector ◽  
Variable Stars ◽  
The Sun ◽  
Proper Motions ◽  
Rr Lyrae ◽  
The Galaxy

It is now possible to determine proper motions of high-velocity objects in such a way as to obtain with some accuracy the velocity vector relevant to the Sun. If a potential field of the Galaxy is assumed, one can compute an actual orbit. A determination of the velocity of the globular clusterωCentauri has recently been completed at Greenwich, and it is found that the orbit is strongly retrograde in the Galaxy. Similar calculations may be made, though with less certainty, in the case of RR Lyrae variable stars.

Distance to SN 1987A and the LMC

1999 ◽  
Vol 190 ◽  
pp. 549-554
Author(s):  
Nino Panagia
Keyword(s):  
Angular Size ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Light Curves ◽  
Distance Modulus ◽  
Absolute Size ◽  
Sn 1987A

Using the new reductions of the IUE light curves by Sonneborn et al. (1997) and an extensive set of HST images of SN 1987A we have repeated and improved Panagia et al. (1991) analysis to obtain a better determination of the distance to the supernova. In this way we have derived an absolute size of the ringRabs= (6.23 ± 0.08) x 1017cm and an angular sizeR″ = 808 ± 17 mas, which give a distance to the supernovad(SN1987A) = 51.4 ± 1.2 kpc and a distance modulusm–M(SN1987A) = 18.55 ± 0.05. Allowing for a displacement of SN 1987A position relative to the LMC center, the distance to the barycenter of the Large Magellanic Cloud is also estimated to bed(LMC) = 52.0±1.3 kpc, which corresponds to a distance modulus ofm–M(LMC) = 18.58±0.05.

International determination of the total motion of the pole

1961 ◽  
Vol 13 ◽  
pp. 29-41
Author(s):  
Wm. Markowitz
Keyword(s):  
Secular Motion ◽  
The Future

A symposium on the future of the International Latitude Service (I. L. S.) is to be held in Helsinki in July 1960. My report for the symposium consists of two parts. Part I, denoded (Mk I) was published [1] earlier in 1960 under the title “Latitude and Longitude, and the Secular Motion of the Pole”. Part II is the present paper, denoded (Mk II).

Time and Latitude in South Africa

1972 ◽  
Vol 1 ◽  
pp. 27-38
Author(s):  
J. Hers
Keyword(s):  
South Africa ◽  
Cape Town ◽  
Astronomical Observations ◽  
Royal Observatory ◽  
The Republic ◽  
Astronomical Determination ◽  
Limited Accuracy ◽  
Better Than

In South Africa the modern outlook towards time may be said to have started in 1948. Both the two major observatories, The Royal Observatory in Cape Town and the Union Observatory (now known as the Republic Observatory) in Johannesburg had, of course, been involved in the astronomical determination of time almost from their inception, and the Johannesburg Observatory has been responsible for the official time of South Africa since 1908. However the pendulum clocks then in use could not be relied on to provide an accuracy better than about 1/10 second, which was of the same order as that of the astronomical observations. It is doubtful if much use was made of even this limited accuracy outside the two observatories, and although there may – occasionally have been a demand for more accurate time, it was certainly not voiced.

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