Georges Zissis

• PhD
• Professor (Full) at Université Toulouse III - Paul Sabatier

This paper presents the results of a numerical investigation by design of experiments of the thermal management of a symmetrical rectangular heat sink for LED lighting placed in a cavity with asymmetrical conditions at its opening. Our mathematical model is validated by an experiment we carried out for an LED placed in a cavity. According to the pr...

In this work, we analyze numerically, using Comsol Multiphysics, the influence of four parameters (the power of the lamp, the ambient temperature, the angle of inclination of the lamp and the number of holes in the lamp cavity) on the evolution of the junction temperature of a LED lamp placed in a multi-hole cavity using a fractional factorial plan...

The transition to a circular economy aims to minimize waste and preserve resources. Lighting as a Service (LaaS) is a model that aligns with the principles of circularity, by providing lighting solutions that may reduce environmental impact and promote sustainability. As lighting technologies have become more sophisticated, LaaS Models have develop...

This paper presents an assistive system for controlling different light sources throw brain signals. The aim is to improve home automation systems specially the lighting systems by developing an interface to integrate the KNX-based lighting systems with brain signals. The proposed system consists of three parts. The first part is for detecting the...

A spectral shift and new emission bands in the green and red regions have been observed in deep blue exciplex-based organic light-emitting diodes (OLEDs) using carbazole-based materials, namely, tris(4-carbazoyl-9-ylphenyl)amine (TCTA). To deeply understand the origin of these new bands, single-layer and bilayer TCTA-based OLEDs subjected to electr...

Temporal light modulation (TLM) is defined as a temporal change in luminous or color quantities of a light source, resulting from fluctuations of the power supply. Research studies published during the past decade helped define new metrics describing well-known visual effects of TLM such as flicker and the stroboscopic effect. Other visual artifact...

La présente invention concerne une diode électroluminescente organique (bien connue sous l'anglicisme « Organic Light Emitting Diode » ou OLED) comprenant une couche de PEDOT dopé, monophasique ou obtenu par voie sèche oxydative, qui joue à la fois le rôle d'anode et de couche d'injection de trous, son procédé de fabrication, un dispositif opto-éle...

Recently, thermal management of LEDs lamps has become increasingly essential due to the widespread integration of LEDs in smart lighting applications. In this work, we focus on the thermal analysis of convective heat transfer using a honeycomb heat sink designed for LEDs lamp cooling. Three different heat sink geometries were examined: an aluminum-...

The paper is devoted to the study of a high-pressure short-arc xenon discharge, which is widely used as a light source. Cathodes of such lamps are often doped with thorium for better cathode operation. As a result, thorium can evaporate into a discharge. The study is based on a model of a short-arc xenon discharge plasma, which includes presence of...

The co-integration of antennas with lighting sources appears as an effective way to distribute broadband networks closer to users, lowering interference and transmitted power, as well as to reduce energy consumption in future lighting systems. We here present an original contribution to the implementation of transparent and invisible antennas with...

In this work, two types of phosphors, a flat surface and a curved surface, are simulated with LightTools software to show that the introduction of curvature on the material can help with heat accumulation and light generation in laser driven phosphor conversion applications.

Intelligent lighting systems use various methodologies comprising both standard protocols, intelligent methods, control systems and sensors. These protocols define the communication among lighting devices and control systems that many open standards allow interoperability among products from different manufacturers. They offer flexibility and a wid...

Electrical lighting uses approximately 13.7% of the world’s electricity and impacts heavily human’s visual performance and also well-being, health and security. Electrical power light sources and lighting systems impact also our planet’s resources and our biotope. After decades of stagnation of the performances of legacy lighting technologies, prod...

Over the past 20 years, the development and adoption of solid-state lighting (SSL) has led to substantial improvements in the quality and efficiency of lighting. This disruptive technology enabled a decoupling of lighting and energy consumption, such that global lighting services have increased while associated energy consumption and greenhouse gas...

Light just seems ”natural” to us, as well as lighting when the ambient level is too low for our needs. This paper is about the Physic and Technologies behind light and lighting, together with a brief description of the Human perception mechanisms. It goes over norms and measurement systems, and summarizes a few of the influences of lighting on Huma...

There is now an increasing emphasis on reducing the overall level of lighting in towns and villages. The priority is to reduce energy consumption thanks to energy costs and decrease a light pollution in towns, villages and general space. This has an understandable impact not only on road safety but a whole range of other situations. The main object...

The history of electric lighting begins in the 19th century with the arc lamps invented in 1802 by Sir Humphrey Davy up to the incandescent lamps at the end of this same century with the patent of Joseph Swan in 1881.

Ionic wind generation is a good candidate for cooling high power LED lights because it is both quiet, with no moving mechanical parts and very energy efficient. This preliminary work relates to a simulation of the corona discharge of a wire and two plates in air under atmospheric pressure. The results for the same structure are compared with previo...

Microgrids are an increasingly popular solution for providing communities and facilities with a reliable, efficient, and resilient energy supply. In a microgrid, several energy sources are combined to form a small self-contained grid that can operate independently of the main grid. Renewable energy sources such as solar, wind, and hydropower are pl...

In a decade, the global lighting industry has undergone a total revolution with the arrival of LED lighting. Indonesia is also undergoing this profound transformation but these light sources are non-linear loads which generate high harmonic currents. These non-linear loads which generate non simusoidal voltage waveforms, which can be harmful to oth...

LED light sources have many advantages but also disadvantages such as temperature sensitivity. Another of these drawbacks concerns the electromagnetic compatibility of electronic ballasts and the generation of electromagnetic disturbances. The generation of these disturbances comes from the DC/DC converter circuits. This paper presents the results...

Recent years have been marked by the evolution of LED lamp applications in homes or electric vehicles such as lighting or signaling systems. Many international standards are designed to protect electronic devices caused by emissions radiated by other electrical systems. This paper studies the radiated interference of electric field caused by a LED...

The optical spectral analysis of the deep or superficial layers of the skin by optical means for the detection of bacteria has considerable advantages: fast, inexpensive and, above all, no traumatic biopsy. Based on a previous study, we have developed a new model for studying skin and soft tissue infections based on ray tracing. The principle of th...

The objective of this study is to develop a digital twin of a street lighting pole, enabling remote control and monitoring according to a smart lighting framework. The project encompasses the creation of a DT-pole model for an entire street and the evaluation of its energy efficiency. A physical prototype is built, integrating sensors for data acqu...

The "Intergovernmental Panel on Climate Change" (IPCC) reports affirm that humanity is in the face of a big challenge due to the climate and ecosystem disruption caused by human activity. After the recent developments in light-emitting diode (LED) and even their integration with connected and smart devices, it's a must to verify that this advanceme...

In this work, we analyze numerically, using Comsol Multiphysics®, the influence of four parameters (the power of the lamp, the ambient temperature, the angle of inclination of the lamp and the number of holes in the lamp cavity) on the evolution of the junction of a LED heat sink placed in a multi-hole cavity using a fractional factorial plan. Taki...

LED lighting devices are today capable of replacing any light source, whatever its luminous power, with unequaled energy efficiency and a considerable lifespan. However, these are sensitive to heat, which is all the more important for high-power LEDs. The greater the power, the larger the heatsink. The active cooling device by ionic winds is a very...

In 2019, Indonesia’s electricity consumption exceeded 278 TWH, or about 1.08 MWh/capita. This value shows a considerable increase in electricity consumption which has doubled in just a decade. Previous studies have shown that the proportion of electricity consumption used for lighting needs is correlated to the country’s GDP. This is generally arou...

Research and development over the last century have historically concentrated on improving one specific aspect of energy efficiency. The market penetration rate for systems using solid-state light sources is currently between 40 and 45 percent, and it is rising. This paper provides an update on the state of lighting technology based on the compilat...

The standing standardized measure for the assessment of flicker severity, the light flickermeter (IEC TR 61547-1:2020), evaluates the flicker irritability level in reference conditions as a necessary simplification. This misestimates the actual level in the presence of other factors known to influence flicker visibility. One such factor is noise, w...

The periods of confinement that we have experienced have highlighted the proven impact of the quality of living spaces on their occupants. While the health crisis has been at the heart of many debates in recent years, it has only served to highlight the issues at stake and to accelerate research into the quality of life in collective housing. The n...

The use of energy-saving lamps in Indonesia is increasing continuously. Currently, the use of LED lamps in residential is only 52%. While the use of CFL lamps is 41% and the incandescent lamp is 7%. Research on energy-saving lamps has resulted in several driver topologies for LED and CFL lamps. With the application of these topologies, energy-savin...

This paper concerns with the design of experiments aimed at determining whether the critical flicker frequency (CFF) is subject to change when the observer is exposed to pulsating sounds. The paper describes the work done in designing the experiments and also reveals data from a preliminary campaign. Data do not form a basis to prove a direct link...

This paper presents a DC-DC LED driver for a 200 W luminaire dedicated to greenhouses lighting applications. Plants are more sensitive to particular radiations for their growth. Hence, we adopted only five LED types that favor photosynthesis process. In order to better control the luminous flux of plants, we used an inverted-Buck converter in each...

Organic Light Emitting diodes (OLED) are lighting devices which are sensitive to a number of intrinsic and extrinsic stresses due to their organic nature. This paper proposes a study of the degradation of warm white, large area OLED panels under accelerated thermal and electrical stress as a tool to estimate their lifespan. The laboratory-induced s...

On the basis of kinetic theory, the stability of an electron beam interacting with inhomogeneous plasma is investigated at Knudsen numbers of the order of 1. The theory has been tested on the example of a low-voltage beam discharge in a rear gas. It is shown that in the case of an inhomogeneous plasma even if the attenuation of a beam is neglected,...

Thermal management of light emitting diodes (LEDs) packages is indispensable to maintain lower operating temperature. The present paper reports a numerical analysis of 45W LEDs module. Two forms of substrate and chips are compared. Results show that circular chips mounted on circular substrate provide lower junction temperature of the package thank...

The LED represents the hot topic has many traditional lighting systems because of their high energy efficiency and lifetime. Nevertheless, if the emissions of harmonic currents are relatively present in the literature because presenting problems on the grid, the measurements of emissions radiated by LED lamps have rarely been carried out. This work...

LED lighting still suffers from its thermal problem linked mainly to the increase in junction temperature. The situation becomes more and more aggravated when it comes to decorative lighting. Indeed, this type of lighting application sometimes requires that the heat sink of the LED lamp be integrated into a narrow space, such as false or sloped cei...

This paper presents a CFD study of ion wind generated airflow which is corona discharge induced flow at the tip of a curved electrode and represents a new cooling method for light emitting diodes (LEDs).The details of a numerical study of the natural convection around the radial radiator with a central pole for the 200 W LED have been examined. The...

Nowadays, Organic Light Emitting Diode (OLED) panels are widely used for displays from smartphone to TV or tablets but, due to numerous qualities (high color rendering index, high efficiency, bendable, no glare, etc.), this kind of light sources is more and more seen as the next generation of wide usage light source. If the color temperature shows...

This paper studies an algorithm for determining the flicker severity of luminous flux produced by artificial lighting systems. The algorithm is defined in time domain and constitutes an alternative to the widely used flicker observer model (light flickermeter) known as IEC

Despite the continuous progress of its technology, thermal management ofLight Emitting Diode packages (LEDs) still the key of their good performances and long lifetime. In this paper, a numerical analysis of 45W LEDs arrays developed using COMSOL Multiphysics®. The PCB LED Board and the heat sink have circular forms. Thirty-six chips are arranged o...

With LED lighting systems, 70% of the energy consumed is lost in thermal form. It would be possible to increase the efficiency of the system by converting this wasted thermal energy into light. Some proposals using Peltier modules have been made. This article is interested in the limits of these solutions by evaluating the drop in the luminous effi...

In order to fulfil the European Commission’s 2050 low-carbon economy vision, the construction sector has new challenges in providing smart, energy-efficient, and sustainable lighting settings for infrastructure, cities, buildings, and industry. Further, the Environmentally Conscious Smart Lighting (ECOSLIGHT) project aims to develop VET training cu...

With LED lighting systems, 70% of the energy consumed is lost in thermal form. It would be possible to increase the efficiency of the system by converting this wasted thermal energy into light. Some proposals using Peltier modules have been made. This article is interested in the limits of these solutions by evaluating the drop in the luminous effi...

In this study, we focused on diffuse reflectance spectroscopy, a rapid and noninvasive spectroscopy technique that has considerable potential for medical diagnosis. In order to better understand and analyze the signals induced by this method, we performed a series of in vivo measurements on healthy and diseased skin. Measurement sites on a human ha...

For several months now, the global pandemic that we are experiencing has highlighted that the quality of the habitat has a proven impact on our quality of life. In this context, it becomes fundamental to take into account the needs of each individual. The aim of this study is to show the benefits of designing the right atmosphere for the place and...

Stray light from commercial greenhouses is becoming a significant problem causing disruption to wildlife activity and annoyance for local residents. To quantify the amount of stray light from a typical large greenhouse the authors have modelled several lighting installations based on a range of generic horticultural light sources. The impact of the...

The global interlaboratory comparison (IC 2017) on measurements of solid-state lighting (SSL) products with goniophotometers was conducted under the International Energy Agency 4E Solid State Lighting Annex with 36 participating laboratories from 19 countries with a total of 42 goniophotometric instruments including mirror-type, near-field type and...

The construction sector faces new challenges in order to provide smart, energy efficient and sustainable lighting environments for infrastructure, cities, buildings and the industry, in order to follow the 2050 low-carbon economy roadmap of the European Commission. In parallel, the Environmentally Conscious Smart Lighting (ECOSLIGHT) project aims t...

The invention relates to electrical engineering, namely to high and ultrahigh pressure gas-discharge lamps. The invention encompasses high power short arc xenon lamps, high pressure mercury short arc lamps, and all other short arc lamps with a cathode doped with an easily ionizable additive and an anode with a diameter larger than that of the gas d...

Luminance is the main feature indicating OLED degradation; however this requires delicate photometric measurements that are difcult and costly to realize in-situ. In this paper, an original luminance decay prediction method not requiring optical measurements will be presented. Analysis of the impedance revealed a strong correlation between the lumi...

This article discusses an original contribution to increase the optical transparency of the Transparent Conducting Oxides (TCOs) and to design optically transparent and invisible antennas that can be integrated in OLEDs light source. To validate the proposed technique, the meshed antenna is compared with the full metal antenna in terms of electrica...

This work deals with a numerical study of natural convection heat transfer around rectangular heat sink in an inclined enclosure. The effects of the cavity orientation and its length on the thermal and dynamic behavior were carried out. Their effects on photometric properties of the LEDs lamp were also evaluated. Results showed that these parameter...

This research proposes a new non-invasive approach for the detection of Mycobacterium ulcerans based on reflectance spectroscopy. Diffuse reflectance spectroscopy (DRS) is a technique that illuminates the tissue surface and analyzes the spectrum of backscattered light, in which the signature of various biochemical species can be identified. This pr...

Organic Light Emitting diodes (OLED), are a lighting technology sensitive to many intrinsic and extrinsic stresses due to its organic character. This paper proposes studying the degradation of warm white, large area OLED panels under accelerated thermal and electrical stress as a tool to estimate their lifespan. The stress recreates the daily turni...

Reducing energy consumption in all areas is an ecological and economic necessity. The energy losses are manifested in most cases by a release of heat which reduces the energy efficiency of the system. The recovery of these thermal losses, if they are in sufficient quantity, can be a solution to reduce the overall energy consumption of the system an...

Light Emitting Diodes emits no IR and no UV and their spectrum is fully in the visible part. But LEDs are not cold and all energy losses are thermal losses. The aim of this paper is to prove the feasibility to reuse the thermal losses to produce light through a thermoelectric module. Papers where Peltier modules are included in LEDs systems are all...

In this article, an optically transparent antenna, integrated in organic light-emitting diodes (OLEDs), is proposed for sub-6 GHz 5G applications. The concept of the mesh geometry is applied to obtain high optical transparency. To validate this technique, the transparent antenna is compared with the non-transparent in terms of electrical, optical a...

Abstract—In this research, an optical design model of an elliptical dual reflector working in the near-ultraviolet (UV)- Visible (UV-VIS) region for the detection of Mycobacterium ulcerans is presented. This approach aims at developing an original, portable, non-invasive and usable on the field diagnostic device. The Henyey-Greenstein scattering sk...

Blue light has proven its impact on melatonin concentration levels, the circadian rythm disruption, body temperature, pupillary reflex and fastening the AMD (Age-related macular degeneration). Humans dialy routine has recently been compromised by the extreme utilization of LED screens (TV, smartphone, computer) that emit a considerable quantity of...

A short-arc xenon discharge of high (super-high) pressure, which is widely used as a light source, has been studied taking into account the evaporation of cathode material (thorium) into the discharge volume. The article is a continuation of the experimental study, results of which were published earlier (IEEE Transactions on Plasma Science, July 2...

The invention relates to an optical system (60) comprising a dichroic plate (61) which is arranged to receive an incident light beam (90) and configured, firstly, to allow a portion of the incident light beam having wavelengths in a first range in the infrared range, referred to as the infrared light beam (92), to pass through it and secondly, to r...

The invention relates to an optical system (60) comprising a dichroic plate (61) which is arranged to receive an incident light beam (90) and configured, firstly, to allow a portion of the incident light beam having wavelengths in a first range in the infrared range, referred to as the infrared light beam (92), to pass through it and secondly, to r...

This paper aims to assess specifically the effects of measurement noise on the evaluation of the flicker metrics defined in IEEE Standard 1789-2015. To this end we compare two analytical approaches and Monte Carlo simulations w.r.t. their ability to cope with natural bias of Flicker Percent and to estimate its measurement uncertainty. Two similar d...

In this research, treated metakaolinite (TMK) was introduced into the TiO 2 photoelectrode to fabricated dye-sensitized solar cells (DSSCs). The photovoltaic cells have four main natural components, i.e., a photosensitizer (carotenoid bixin), photoelectrode (TiO 2 /kaolinite), electrolyte (glycerine carbonate derivative), and counter-electrode (car...

The use of light emitting diodes (LEDs) for lighting requires high level of thermal management. In fact, the lamp is more efficient when operating under lower junction temperature. In this paper, we present a three dimensional analysis of 106 W multi-chip LEDs lamp using finite element method. A comparison between two different substrate designs wa...

We report a methodological approach for simulating luminary output radiation, which is achieved by mixing light-emitting diodes (LEDs) in order to match any plant absorption spectrum. Various recorded narrow-band LED spectra of different colors were first characterized and then fitted with a multi-Gaussian model. An optimizing procedure computed th...

Nepal houses many traditional and cultural sites rich in historical cultural diversity. These sites are also economically important to the nation. These monuments show the culture and the living beliefs of the communities; hence, people from all over the world are attracted to such place to observe the beauty and to feel the spirit and the conserva...

The use of color and lighting as factors for adapting the housing of the elderly is tending to develop, in response to demographic data on the aging of the population and its impact on lifestyles. Adapting the environment for those over 60 years has become a national issue for public policy. So this article takes stock of the studies carried out on...