Guy Durinck

KU Leuven | ku leuven · Department of Electrical Engineering (ESAT)

Students in the final stage of their professional bachelor, who want to bridge to a Master’s programme in Engineering Technology, are often lacking mathematical skills. We want to smoothen the transition to university by preparing them in advance. Therefore an online mathematics course (SPOC) and a math test are developed. Students had the opportun...

Ray tracing is a useful tool in the optical de‑ sign of luminaires. Usually simulations are per‑ formed atone wavelength. However, in some lu‑ minaires optical components are incorporated to alter the spectrum of the light source. In a re‑ tail environment, luminaires equipped with a di‑ chroic filter are commonly used to enhance the attractiveness...

During the last years, evidence has arisen for the ability of crustaceans to suffer from stress and noxious situations. This has led to an increasing public concern for crustacean welfare. Due to the interest in intensification of crayfish aquaculture, the question arises whether artificial culture conditions may impact these crustaceans' welfare....

Design, construction and calibration of a setup to measure spectral underwater irradiance in aquaria.

The adding-doubling method can be used to determine the reflection and transmission characteristics of materials exhibiting bulk scattering and photoluminescence. In this work, the method is adapted to allow the implementation of luminescent cascade systems. Distinctive for these systems are the multiple re-absorption and re-emission events by the...

Luminescent down-shifting (LDS) layers applied on top of solar cells can potentially increase solar cell performance due to the better match of the incident irradiance spectrum reaching the cell to its spectral response. In this study, the adding-doubling tool is presented, which allows fast predictions of the influence of LDS sheets on solar cell...

To obtain realistic results in lighting simulation software, realistic models of light sources are needed. A near-field model of a light source is accurate, and can be obtained by a near-field goniophotometer. This type of goniophotometer is conventionally equipped with a V(λ)-filter. However, the advent of new light sources with spatial- or angula...

Absorption and scattering properties of a YAG:Ce phosphor imbedded in silicone oil were derived using a modified inverse adding-doubling method. The Two Term Henyey Greenstein phase function offered the best description of the scattering behavior.

The adding-doubling method is proposed as alternative to ray tracing simulations for the modeling of solar modules incorporating a luminescent down-shifting layer. The method is applied to investigate the luminescent effect under various irradiation conditions.

An integrating sphere-based setup to obtain a quick and reliable determination of the internal quantum efficiency of strongly scattering luminescent materials is presented. In literature, two distinct but similar measurement procedures are frequently mentioned: a "two measurement" and a "three measurement" approach. Both methods are evaluated by ap...

To perform adequate simulations of luminescent cascade systems, a hybrid method combining a commercial ray tracer and a programming tool is presented. True Monte Carlo algorithms for luminescent materials, treating each ray individually, are adapted to allow wavelength conversion of ray sets. Two solutions for the wavelength conversion of ray sets...

Monte Carlo ray tracing is an important simulation tool in applications where fluorescence is present, e.g. in bio-medical applications and in the design of luminaires and luminescent solar concentrators. A frequently used ray tracing procedure for fluorescence is the ‘dual stage’ approach. In this approach, first, all sources are traced through th...

To enhance the efficiency of solar cells, a luminescent down shifting layer can be applied in order to adapt the solar spectrum to the spectral internal quantum efficiency of the semiconductor. Optimization of such luminescent down shifting layers benefits from quick and direct evaluation methods. In this paper, the potential of the adding-doubling...

The accuracy of optical simulations including bulk diffusors is heavily dependent on the accuracy of the bulk scattering properties. If no knowledge on the physical scattering effects is available, an iterative procedure is usually used to obtain the scattering properties, such as the inverse Monte Carlo method or the inverse adding-doubling (AD) m...

Discussion (case) of the organisation of university teacher mobility in multi campus teaching.

The adding-doubling method can be used to determine the reflection and transmission characteristics of fluorescent materials. In this work, the method was adapted to allow the implementation of fluorescent particles with a significant overlap between excitation and emission spectrum. The proposed method was validated by comparing its results to the...

Ray files offer a very accurate description of the optical characteristics of a light source. This is essential whenever optical components are positioned in close proximity (near-field) of the light source in order to perform accurate ray tracing simulations. However, a ray file does not allow for a direct simulation of the spatial luminance distr...

The reliability of ray tracing simulations is strongly dependent on the accuracy of the input data such as the bidirectional reflectance distribution function (BRDF). Software developers offer the possibility to implement BRDF data in different ways, ranging from simple predefined functions to detailed tabulated data. The impact of the accuracy of...

Diffusors are widely used optical components having numerous applications. They are commonly used to homogenize light beams and to create particular intensity distributions. The angular scattering profile of bulk scattering diffusing materials is determined by three bulk scattering parameters that are, however, not commonly available. This hampers...

Discussion of BRDF measurements of holographic diffusers

Optical simulations are a common tool in the development of luminaires for lighting applications. The reliability of the virtual prototype is strongly dependent on the accuracy of the input data such as the emission characteristics of the light source and the scattering properties of the optical components (reflectors, filters and diffusers). These...

The adding-doubling method was investigated for the modeling of solar cell encapsulation. Good agreement was found between the adding-doubling method and Monte Carlo simulations. The adding-doubling method reduces computation time by a factor 240.

In this paper a fast, yet accurate method to estimate the spectral and angular distribution of the scattered radiation of a fluorescent material is described. The proposed method is an extension of the adding-doubling algorithm for non-fluorescent samples. The method is validated by comparing the spectral and angular transmittance and reflectance c...

Discussion of experimental data and simulation results concerning LED luminaires.

Discussion of optical measurements and simulationa of an LED lighting device based on an optical mixing chamber.

Many manufacturers and distributors of LED tubes claim energy savings of 50% and more when replacing T8 fluorescent tubes with LED linear replacement lamps. Above, most distributors pretend that the same visual performance and comfort will be maintained after such replacement. Optical and electrical parameters of twelve commercially available LED t...

The use of a ray file to model the optical characteristics of a light source is a well-known and popular method to achieve accurate results when simulating luminous intensity distributions of luminaires, especially if the source is interacting with optical components at a close distance. However, lighting industry becomes more and more interested i...

A major problem in solid state lighting is the limited flux emitted by a single power light emitter diode (LED). This flux is insufficient for most lighting applications. A possible solution is using not one but an array of LEDs as a light source. However, the optical control of the flux emitted by such a spatially extended and inhomogeneous light...

In a context of closer cooperation, six institutes of higher engineering education in Flanders teaching topics related to electrical power engineering and automation joined forces in designing and implementing a set of hands-on courses on different aspects of intelligent electrical systems (lighting, domotics, power electronics, EMC, …). It is base...

The evolution of the experimental frequency width of symmetric modes of an aluminum plate is studied as a function of the angle of incidence below the first critical angle. It is found that the frequency width predicted by resonant scattering theory, corrected for the directivity of emitter and receiver, generally explains the experimental frequenc...

From theory it is predicted that Lamb modes having a positive group velocity and those having a negative group velocity correspond to, respectively, negative and positive peaks on a spectrum showing the angular derivative of the phase of the transmission coefficient of the elastic plate. Experimental data are presented here that support this predic...

Discussion of the nature of acoustic modes of a fluid loaded plate.

Discussion of the inadequacy of Resonant Scattering Theory in modelling the modes of fluid loaded plates.

The transmission frequency spectrum at normal incidence of a water-loaded glass plate has been studied searching for modes of a predominantly leaky nature. Near the cut-off frequency of the mode A2, an antisymmetric mode A3′ of a predominantly leaky nature was observed in the frequency spectrum of the leaky field. The mode A3′ is completely separat...

The problem of normal propagation modes of a plate submerged in a fluid is usually treated by considering continuous leaky Lamb waves or by considering transient waves. Angular plate resonances are associated with modes obtained by the first approach, whereas frequency plate resonances are associated with modes obtained using the second method. The...

Discussion of an experimental technique to determine the width of Lamb modes.

The reflection and transmission coefficient of a plate can be expressed as a function of frequency at fixed angle of incidence or as a function of angle of incidence at fixed frequency. In the first situation, the transmission coefficient can be considered as a superposition of frequency resonances, while in the latter case it can be considered as...

The mechanical modes of a fluid loaded elastic plate are characterized by a complex frequency and a complex slowness. The complex frequency describes the transient nature of the mode. The complex slowness models the energy radiation (leakage) from the plate to the fluid as the mode propagates along the plate. Until now this mixed transient-leaky na...

A method to determine the transversal wave velocity in submerged plates is presented. It is based on an analysis of the transmission coefficient of the plate between its first and second critical angles, where the only bulk waves present in the plate are shear waves. According to the resonance theory of plate modes, the parametric representation of...

Discussion of acoustic measurements of Lamb modes.

Discussion of an experimental technique.

Using a high?resolution digital oscilloscope and advanced datahandling plate modes near normal incidence, other than those identified by Lamb, were studied. This search was led by the complex roots of the dispersion relation for a plate in water. Solutions with a complex wave number component in the propagation direction indeed reveal near normal i...

This paper deals with the dispersion of Lamb waves in solid bilayers. The theoretical dispersion curves of the bilayers in air are analyzed in terms of the dispersion in the decoupled layers. Experimental data confirm the numerical analysis. The results show how coupling between the Lamb modes of the substrate and those of the coating makes the bil...

In analogy with the coupling constant of coupled oscillators we defined a coupling constant kc for a liquid bilayer. It measures the strenght of the mutual influence of the normal propagation modes of the decoupled layers, on the modes of the bilayer. The material parameter which determines the strenght of the coupling turns out to be the ratio of...

The surface properties of TiO2-anatase are of great importance in chemical technology because this material is frequently used as a support for oxide catalysts. In the present work, surface phonons were observed on the (001) and (100) surfaces of anatase minerals by means of HREELS. After comparison with theoretical values and infrared data a preli...

First presentation of measured HREELS spectra of anatase on V2O5.