Optimization Methods for Spectral Synthesizing of a Tuneable Colour Light Source

2018 ◽  
pp. 99-108
Author(s):  
Nina Carli ◽  
Armin Sperling ◽  
Grega Bizjak

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.

Author(s):  
Ran Zhao ◽  
Chengying Xu

In this paper, we present a systematic modeling method of direct drive systems. Experiments are designed to decouple and model friction and force ripple separately, which are two major sources of tracking error. Three different optimization methods, least square method, nonlinear least square method and particle swarm optimization are used for parameter optimization. The analytical form of the model makes it easy to use in engineering practices. All results are obtained and verified experimentally. The method presented in this paper can also be used to model other mechanical systems.


2005 ◽  
Vol 08 (07) ◽  
pp. 989-998 ◽  
Author(s):  
HIROSHI KONNO ◽  
SUMITO ITO

We will develop an efficient method for estimating a smooth nonnegative forward rate sequence using the market price of riskless bonds. This method is an improvement of the classical Carleton–Cooper's method based on standard least square method, which often generates a non-smooth forward rate sequence and hence is not used in practice. The method to be proposed in this paper is intended to resolve this difficulty. We will impose a smoothness condition while maintaining the fitting error within an acceptable level. The resulting optimization problem is shown to be convex in the region of interest. Therefore, we can calculate a globally optimal solution very fast by standard nonlinear programming algorithms. We will demonstrate that this method generates a smooth forward rate sequence at the expense of a very small increase of fitting error.


2020 ◽  
pp. 90-98
Author(s):  
Nina Carli ◽  
Armin Sperling ◽  
Grega Bizjak

A spectrally tuneable colour light source (TCLS) has been designed and constructed at Physikalisch-Technische Bundesanstalt (PTB), Germany. It consists of an integrating sphere with 24 LEDs which are driven by a computer-controlled power supply. It is intended for producing any visible spectral distribution and to mimic various light sources for use in laboratories as a calibration source. With the help of an integrated spectrometer, a closed loop operation was introduced to improve the performance of the TCLS and to spectrally stabilize its output spectrum. Before practical realization of the TCLS a series of simulations have been made to predict its performance and capability with a number of different target spectrums. During the practical implementation we have encountered difficulties, namely optimization of the output spectrum, dependency of LED spectra on the electric current through the LED and temperature of the LED, non-linearity of LED’s luminous flux with respect to electric current through the LED and some difficulties with small synthesis coefficient values, which were all successfully solved.


2008 ◽  
Vol 18 (01n02) ◽  
pp. 107-129 ◽  
Author(s):  
FRIEDRICH EISENBRAND ◽  
STEFAN FUNKE ◽  
ANDREAS KARRENBAUER ◽  
DOMAGOJ MATIJEVIC

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.


2013 ◽  
Vol 31 (4) ◽  
pp. 643 ◽  
Author(s):  
Lourenildo W.B. Leite ◽  
Wildney W.S. Vieira

ABSTRACT. This paper describes an investigation about the sensitivity and ambiguity of the Common Reflection Surface (CRS) stack operator parameters (v0, RNIP,RN, α0), and their resolution in terms of statistical properties of the solution of a nonlinear multi-parametric optimization problem for surface fitting between the forward model and a synthetic data, in the least-square sense. The sensitivity method is borrowed from dynamic system analysis and synthesis, and the definitions are based on the Miller-Murray model. The results are analyzed in terms of the CRS attributes search strategies during the stack process. The investigation principle is to combine global and local optimization methods to reach a minimum of the object function of minimization, where the problem matrix has a better linear relation to the parameters. A first search for a minimum is performed with a controlled random search method, followed by a gradient method for the last steps fo the optimization to calculate the data and parameter resolution and covariance matrices, and any further model statistical properties. The sensitivity functions are represented by the columns of the optimization problem matrix, and they in general exhibit a linear behavior instead of a convex form; as a result, this linear behavior establish thenecessity of a good starting point for the optimized multi-parametric attributes search.Keywords: CRS attributes, sensitivity analysis, resolution, ambiguity. RESUMO. Este trabalho descreve uma investigação sobre a sensitividade e ambiguidade dos parâmetros (v0,RNIP, RN, α0) do operador de empilhamento CRS, e suas resoluções em termos das propriedades estatísticas da solução de um problema não-linear multi-paramétrico do ajuste da superfície de um modelo direto à de dados sintéticos, no sentido do quadrados-mínimos. O método da sensitividade é adaptado da análise e síntese de sistemas dinâmicos, e as definições são baseadas no modelo Miller-Murray. Os resultados são analisados em termos das estratégias de busca dos atributos CRS durante o processo de empilhamento. O princípio da investigação é combinar métodos de otimização global e local para alcançar um mínimo da função objeto de minimização, onde a matriz do problema tem uma melhor relação linear com os parâmetros. A primeira busca de um mínimo é realizada com um método de busca aleatória controlada, seguida por um método do gradiente para os últimos passos da otimização para calcular as matrizes resolução e covariância dos dados e parâmetros, e quaisquer propiedades estatísticas do modelo. As funções sensitividade são representadas pelas colunas da matriz otimização do problema, e em geral elas exibem um comportamento linear em vez de uma forma convexa; como resultado, este comportamento linear estabelece a necessidade de um bom ponto inicial para a busca multi-paramétrica otimizada dos atributos.Palavras-chave: atributos CRS, análise de sensibilidade, resolução, ambiguidade.


1981 ◽  
Vol 20 (06) ◽  
pp. 274-278
Author(s):  
J. Liniecki ◽  
J. Bialobrzeski ◽  
Ewa Mlodkowska ◽  
M. J. Surma

A concept of a kidney uptake coefficient (UC) of 131I-o-hippurate was developed by analogy from the corresponding kidney clearance of blood plasma in the early period after injection of the hippurate. The UC for each kidney was defined as the count-rate over its ROI at a time shorter than the peak in the renoscintigraphic curve divided by the integral of the count-rate curve over the "blood"-ROI. A procedure for normalization of both curves against each other was also developed. The total kidney clearance of the hippurate was determined from the function of plasma activity concentration vs. time after a single injection; the determinations were made at 5, 10, 15, 20, 30, 45, 60, 75 and 90 min after intravenous administration of 131I-o-hippurate and the best-fit curve was obtained by means of the least-square method. When the UC was related to the absolute value of the clearance a positive linear correlation was found (r = 0.922, ρ > 0.99). Using this regression equation the clearance could be estimated in reverse from the uptake coefficient calculated solely on the basis of the renoscintigraphic curves without blood sampling. The errors of the estimate are compatible with the requirement of a fast appraisal of renal function for purposes of clinical diagknosis.


2019 ◽  
pp. 101-107
Author(s):  
Sergei A. Stakharny

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.


2015 ◽  
Vol 5 (2) ◽  
pp. 1
Author(s):  
Miftahol Arifin

The purpose of this research is to analyze the influence of knowledge management on employee performance, analyze the effect of competence on employee performance, analyze the influence of motivation on employee performance). In this study, samples taken are structural employees PT.centris Kingdom Taxi Yogyakarta. The analysis tool in this study using multiple linear regression with Ordinary Least Square method (OLS). The conclusion of this study showed that the variables of knowledge management has a significant influence on employee performance, competence variables have an influence on employee performance, motivation variables have an influence on employee performance, The analysis showed that the variables of knowledge management, competence, motivation on employee performance.Keywords: knowledge management, competence, motivation, employee performance.


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