ENERGY-AWARE STAGE ILLUMINATION

Consider the following illumination problem: given a stage represented by a line segment L and a set of light sources represented by a set of points S in the plane, assign powers to the light sources such that every point on the stage receives a sufficient amount – e.g. one unit – of light while minimizing the overall power consumption. Under the assumption that the amount of light arriving from a fixed light source decreases rapidly with the distance from the light source, this becomes an interesting optimization problem. We propose to reconsider the classical illumination problems as known from computational geometry literature under this light attenuation model. This paper examines the simple problem introduced above and presents different solutions, based on convex optimization, discretization and linear programming, as well as a purely combinatorial approximation algorithm. Some experimental results are also provided.

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Effect of different soldering temperatures on the properties of COB light source

Soldering & Surface Mount Technology ◽

10.1108/ssmt-03-2021-0010 ◽

2021 ◽

Vol ahead-of-print (ahead-of-print) ◽

Author(s):

Zhao Wang ◽

Yuefeng Li ◽

Jun Zou ◽

Bobo Yang ◽

Mingming Shi

Keyword(s):

Light Source ◽

Void Ratio ◽

Light Attenuation ◽

Luminous Flux ◽

Luminous Efficiency ◽

Junction Temperature ◽

Light Sources ◽

Content Type ◽

Soldering Temperature ◽

Practical Engineering

Purpose The purpose of this paper is to investigate the effect of different soldering temperatures on the performance of chip-on-board (COB) light sources during vacuum reflow soldering. Design/methodology/approach First, the influence of the void ratio of the COB light source on the steady-state voltage, luminous flux, luminous efficiency and junction temperature has been explored at soldering temperatures of 250°C, 260°C, 270°C, 280°C and 290°C. The COB chip has also been tested for practical application and aging. Findings The results show that when the soldering temperature is 270°C, the void ratio of the soldering layer is only 5.1%, the junction temperature of the chip is only 76.52°C, and the luminous flux and luminous efficiency are the highest, and it has been observed that the luminous efficiency and average junction temperature of the chip are 107 lm/W and 72.3°C, respectively, which meets the requirements of street lights. After aging for 1,080 h, the light attenuation is 84.64% of the initial value, which indicates that it has higher reliability and longer life. Originality/value It can provide reference data for readers and people in this field and can be directly applied to practical engineering.

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Optimization Methods for Spectral Synthesizing of a Tuneable Colour Light Source

Light & Engineering ◽

10.33383/2018-023 ◽

2018 ◽

pp. 99-108

Author(s):

Nina Carli ◽

Armin Sperling ◽

Grega Bizjak

Keyword(s):

Light Source ◽

Optimization Problem ◽

Least Square Method ◽

Optimization Methods ◽

Least Square ◽

Light Sources ◽

Output Spectrum ◽

Constrained Problem ◽

Target Spectrum ◽

Spectral Distributions

A method for a tuneable colour light source (TCLS) output spectrum synthesizing is described. A TCLS is a multichannel LED light source, which is able to mimic and produce different spectral distributions and can be used for the realization of different spectra, e.g. the spectra of different CIE standard illuminants. The synthesizing of output spectrum is actually an optimization problem of tuning the output spectrum of a TCLS to the target spectrum. It is also a so called constrained problem as output spectrum is produced by adding the weighted spectra of used light sources (e.g. singlecolour LEDs) and due to the fact that there is no “negative light”. Because of that usual optimization methods like least square method cannot be used. A novel synthesizing method based on a constrained optimization process was developed and tested on the laboratory TCLS to be used for calibration purposes. The developed synthesizing method, described in this paper, gives good results but comparison with more simple methods shows that also these can be successfully used.

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Organic Light Emitting Diodes - Innovative Light Sources

Light & Engineering ◽

10.33383/2018-157 ◽

2019 ◽

pp. 101-107

Author(s):

Sergei A. Stakharny

Keyword(s):

Light Source ◽

Organic Light Emitting Diodes ◽

Organic Leds ◽

Light Sources ◽

High Quality ◽

Light Emitting ◽

Organic Light ◽

Lighting Systems ◽

Physical Principles ◽

Prospects Of Application

This article is a review of the new light source – organic LEDs having prospects of application in general and special lighting systems. The article describes physical principles of operation of organic LEDs, their advantages and principal differences from conventional non-organic LEDs and other light sources. Also the article devoted to contemporary achievements and prospects of development of this field in the spheres of both general and museum lighting as well as other spheres where properties of organic LEDs as high-quality light sources may be extremely useful.

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Analysis on High-Power Seaport LED Luminaire with Uniform Light Distribution Based on Optimized Lens and Heatsink

Applied Sciences ◽

10.3390/app11094035 ◽

2021 ◽

Vol 11 (9) ◽

pp. 4035

Author(s):

Jinsheon Kim ◽

Jeungmo Kang ◽

Woojin Jang

Keyword(s):

Light Source ◽

High Power ◽

Heat Dissipation ◽

Light Emitting Diode ◽

Light Distribution ◽

Light Sources ◽

Led Light ◽

High Power Led ◽

Distribution Requirement ◽

Lighting Application

In the case of light-emitting diode (LED) seaport luminaires, they should be designed in consideration of glare, average illuminance, and overall uniformity. Although it is possible to implement light distribution through auxiliary devices such as reflectors, it means increasing the weight and size of the luminaire, which reduces the feasibility. Considering the special environment of seaport luminaires, which are installed at a height of 30 m or more, it is necessary to reduce the weight of the device, facilitate replacement, and secure a light source with a long life. In this paper, an optimized lens design was investigated to provide uniform light distribution to meet the requirement in the seaport lighting application. Four types of lens were designed and fabricated to verify the uniform light distribution requirement for the seaport lighting application. Using numerical analysis, we optimized the lens that provides the required minimum overall uniformity for the seaport lighting application. A theoretical analysis for the heatsink structure and shape were conducted to reduce the heat from the high-power LED light sources up to 250 W. As a result of these analyses on the heat dissipation characteristics of the high-power LED light source used in the LED seaport luminaire, the heatsink with hexagonal-shape fins shows the best heat dissipation effect. Finally, a prototype LED seaport luminaire with an optimized lens and heat sink was fabricated and tested in a real seaport environment. The light distribution characteristics of this prototype LED seaport luminaire were compared with a commercial high-pressure sodium luminaire and metal halide luminaire.

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Detectors and light-sources for optical spectrometry: from a 3D-printed light-source to a self-powered sensor fabricated on a flexible polymeric substrate, and from there on to an IoT-enabled "smart" system

2019 IEEE International Conference on Flexible and Printable Sensors and Systems (FLEPS) ◽

10.1109/fleps.2019.8792321 ◽

2019 ◽

Author(s):

Amy Hall ◽

Grace Xuan Kong ◽

Vassili Karanassios

Keyword(s):

Light Source ◽

Light Sources ◽

Polymeric Substrate ◽

Smart System ◽

Optical Spectrometry ◽

3D Printed ◽

Self Powered

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Towards the Optimum Light Source Spectrum

Advances in OptoElectronics ◽

10.1155/2010/596825 ◽

2010 ◽

Vol 2010 ◽

pp. 1-9 ◽

Cited By ~ 8

Author(s):

Andrew Chalmers ◽

Snjezana Soltic

Keyword(s):

Light Source ◽

Large Scale ◽

Source Spectrum ◽

Light Sources ◽

Luminous Efficacy ◽

Light Emitting ◽

Spectral Bands ◽

Good Energy ◽

Lighting Systems ◽

Colour Rendering

This paper is concerned with designing light source spectra for optimum luminous efficacy and colour rendering. We demonstrate that it is possible to design light sources that can provide both good colour rendering and high luminous efficacy by combining the outputs of a number of narrowband spectral constituents. Also, the achievable results depend on the numbers and wavelengths of the different spectral bands utilized in the mixture. Practical realization of these concepts has been demonstrated in this pilot study which combines a number of simulations with tests using real LEDs (light emitting diodes). Such sources are capable of providing highly efficient lighting systems with good energy conservation potential. Further research is underway to investigate the practicalities of our proposals in relation to large-scale light source production.

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Adaptive Complex Method for Efficient Design Optimization

Volume 6: 33rd Design Automation Conference, Parts A and B ◽

10.1115/detc2007-34773 ◽

2007 ◽

Cited By ~ 2

Author(s):

Marcus Pettersson ◽

Johan O¨lvander

Keyword(s):

Design Optimization ◽

Optimization Problem ◽

Global Optimum ◽

Direct Search ◽

Complex Method ◽

Efficient Design ◽

Direct Search Methods ◽

Simulation Based ◽

Set Of Points ◽

Quasi Newton

Box’s Complex method for direct search has shown promise when applied to simulation based optimization. In direct search methods, like Box’s Complex method, the search starts with a set of points, where each point is a solution to the optimization problem. In the Complex method the number of points must be at least one plus the number of variables. However, in order to avoid premature termination and increase the likelihood of finding the global optimum more points are often used at the expense of the required number of evaluations. The idea in this paper is to gradually remove points during the optimization in order to achieve an adaptive Complex method for more efficient design optimization. The proposed method shows encouraging results when compared to the Complex method with fix number of points and a quasi-Newton method.

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Hybrid-Light-Source Stereolithography for Fabricating Macro-Objects With Micro-Textures

Volume 1: Additive Manufacturing; Advanced Materials Manufacturing; Biomanufacturing; Life Cycle Engineering; Manufacturing Equipment and Automation ◽

10.1115/msec2021-63717 ◽

2021 ◽

Author(s):

Wenxuan Jia ◽

Yuen-Shan Leung ◽

Huachao Mao ◽

Han Xu ◽

Chi Zhou ◽

...

Keyword(s):

Light Source ◽

Dimensional Accuracy ◽

Beam Width ◽

Surface Structures ◽

Light Sources ◽

Scanning Method ◽

Hardware System ◽

Building Area ◽

Micro Features ◽

Display Resolution

Abstract Microscale surface structures are commonly found on macroscale bodies of natural creatures for their unique functions. However, it is difficult to fabricate such multi-scale geometry with conventional stereolithography processes that rely on either laser or digital micromirror device (DMD). More specifically, the DMD-based mask projection method displays the image of a cross-section of the part on the resin to fabricate the entire layer efficiently; however, its display resolution is limited by the building area. In comparison, the laser-based vector scanning method builds smooth features using a focused laser beam with desired beam-width resolution; however, it has less throughput for its sequential nature. In this paper, we studied the hybrid-light-source stereolithography process that integrates both optical light sources to facilitate the fabrication of macro-objects with microscale surface structures (called micro-textures in the paper). The hardware system uses a novel calibration approach that ensures pixel-level dimensional accuracy across the two light sources. The software system enables designing the distribution and density of specific microscale textures on a macro-object by generating projection images and laser toolpaths for the two integrated light sources. Several test cases were fabricated to demonstrate the capability of the developed process. A large fabrication area (76.8 mm × 80.0 mm) with 50 μm micro-features can be achieved with a high throughput.

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