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how to create barcode in vb.net 2008 The Role of Sensors in the 21st Century in Software
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Barcode Maker In VS .NET Using Barcode drawer for Visual Studio .NET Control to generate, create bar code image in .NET framework applications. Generate Bar Code In Visual Studio .NET Using Barcode generation for .NET framework Control to generate, create bar code image in .NET applications. 1.15.5 The Inverse Square Law
The inverse square law tells us that the illumination is inversely proportional to the square of the distance between the point source and the surface, in other words: E1 D2 = 2 2 E2 D1 If you have a fixture that can be treated as a point source, where the distance from the surface is large, and you measure the illumination at 20 feet as 2000 Fc at the beam center, then at 40 feet the illumination is 500 Fc at the beam center. 1.15.6 The Cosine Law
Effective illumination is proportional to the cosine of the angle of incidence of the light on the surface. It is the angle between the direction of the light and the perpendicular to the surface (Fig. 1.21). E2 = E1 cos = E1 sin Here are a few cases: When the surface is tilted by an angle of 30 , the illumination is reduced by a factor of 0.87 45 0.71 60 0.5 FIGURE 1.21 Illumination at the O point on surfaces 1 and 2.
Source
90 O E2
The Role of Sensors in the 21st Century
1.15.7 The Difference Between Lumen and Watt
Lumen is a unit of the photometric system and Watt belongs to the radiometry system. Both characterize a power of light flow. However, lumen is power related to human eye sensitivity. Therefore, lights with the same power in watts, but that are different colors have different luminous fluxes, because the human eye has different sensitivity at different wavelengths. At a wavelength of 555 nm (maximum eye sensitivity), 1 watt equals 683 lumens (lm). Highpower sources of infrared radiation produce no lumen output, so the human eye can t see it. However, in order to calculate the total power absorbed by a surface to estimate temperature increase, for example, lumen flux must be transferred to watts. This can be done by using a spectral luminous efficiency curve, which can be found in many photometry handbooks. Calculating Beam Angles
If the distance from a fixture to the screen is known (which is a much larger value than fixture length), as well as the image diameter (Fig. 1.22), then: = 2 arctan D 2L D  image diameter Screen
L  distance
Fixture
FIGURE 1.22
Calculation of beam angle.
One
In most practical cases, the following approximation is true: = 57 . 3 Example: distance = 20 feet image diameter = 5 feet Exact formula gives the angle = 14.25
In the case of a soft edge light image diameter, it is usually measured at the point where illumination is 50 percent (beam angle) or 10 percent (field angle) of the center illumination. Calculating Lumens Output Luminous Flux
The beam radius is divided into n equal parts (radii and illumination reading values are indexed from 0, at the beam center, to n 1, at the beam edge). See Fig. 1.23. Calculating Center and Edge Points Two Points: P = 2 . 1R 2 (E1 + 0 . 5E0 ) 1.15.11 Calculating Center, Middle, and Edge Points Three Points: P = 1 . 3R 2 (E2 + 1 . 2E1 + 0 . 2E0 ) Beam Profile E0 E1
En 1 Radius Rn 1 = Rbeam
R0 = 0 R1
FIGURE 1.23
Calculation of lumens output.
The Role of Sensors in the 21st Century
Calculating Four Calculation Points: P = 0 . 93R 2 (E3 + 1 . 5E2 + 0 . 75E1 + 0 . 125E0 ) Calculating Five Calculation Points: P = 0 . 72R 2 (E4 + 1 . 64E3 + 1 . 09E2 + 0 . 55E1 + 0 . 09E0 ) Calculating Eight Points: P = 0 . 43R 2 (E7 + 1 . 8E6 + 1 . 5E5 + 1 . 2E4 + 0 . 9E3 + 0 . 6E2 + 0 . 3E1 + 0 . 05E0 ) where P = total lumens R = beam radius E = illumination In the case of a soft edge fixture, where the image size is taken at 10 percent of the center illumination (field angle), the formula becomes: P = 1 . 26R 2Ecenter

