Natural organic dyes suffer from degradation during the time. Therefore, the works of art need to be restored and the identification of dyes by analytical methods is important here. The possibilities of using three separation (thin-layer chromatography - TLC, capillary zone electrophoresis - CZE, and micellar electrokinetic chromatography - MEKC) and two spectroscopic (infrared microspectroscopy - IR and Raman microspectroscopy) methods for the identification of red dyes (acaroid, brazil, dragon blood, kamala, logwood, cochineal, madder, lac, and sandalwood) were studied and critically discussed. In TLC, under optimised conditions (silicagel with octadecyl, 80/20 (v/v) MeOH/1% TEA in 0.1 mol·dm-3 acetate buffer, pH 5, and 80/20 (v/v) MeOH/1% TEA in 0.025 mol·dm-3 tetraborate buffer, pH 7 and 9), the stain broadening of sandalwood, logwood, acaroid, dragon blood, and brazil was observed. Carminic acid, haematein and purpurin were not detected. A comparison of CZE and MEKC showed that MEKC was superior as it permits separation of all analytes, using 0.015 mol·dm-3 sodium dodecyl sulfate in 0.01 mol·dm-3 tetraborate buffer, pH 8.5, at a voltage of 20 kV. The developed method was validated and applied to the identification of dyes in Rubia tinctorum, Rubia cordifolia, and in the mycelium of fungi...

Brightness reversion, also known as yellowing, is a well-known phenomenon which means that the brightness of paper products decreases during ageing. The name of this phenomenon is based on that paper products usually change in color towards yellow during ageing. Yellowing is considered to occur due to a mixture of chemical and physical factors, which makes it a complex problem for the pulp & paper industry. The majority of the literature and research conducted with respect towards yellowing claims that light and heat is the two main factors that contributes the most to a brightness reversion, depending on the type of pulp and process that is utilized. Smurfit Kappa in Piteå is a manufacturer of the paper grade Kraftliner and has during some occasions noted unstable brightness. Based on previous work at Smurfit Kappa, it is known that the finished liners produced from bleached pulp in a completely chlorine-free process is very sensitive to heat, especially for longer periods of time during storage. It has also been documented that the storage temperature for paper products is of great importance, especially the cooling rate of the paper-rolls from production, which could take around two weeks to reach the ambient temperature. This thesis work, alongside with a literature study as a basis will examining the effect of pH towards yellowing during thermal exposure. Through a factorial experiment it was initially found that the yellowing is favored by higher temperatures in conjunction with lower pH values. In order to obtain a brightness reversion of a paper product within a reasonable timeframe an accelerated aging method was used according to the ISO standard 5630-1. Throughout this thesis is the brightness reversion expressed in the so-called b* value, which indicates the color change from blue to yellow. Further experiments, including ageing methods with moisture, also concluded that an acidic pH results in a more severe yellowing. It was also observed that the pH was decreasing during experiments of pulp storage, this most likely to the chemical phenomena known as acidic hydrolysis. The b*-value seemed to be favorable of the decreased pH, thus could the pulp be stored at pH around 8 instead of 9-10 in order to suppress potential yellowing reactions.  Furthermore, it was found that cooling of the paper resulted in a decrease of the b* value, it is however unclear what causes this phenomenon but a theory could be that chromophoric groups are being deactivated/activated due to the temperature changes and hence making the phenomena reversible. / Eftergulning är ett välkänt fenomen som innebär att ljusheten hos pappersprodukter minskar när dessa åldras. Namnet på detta fenomen grundar sig i att pappersprodukter vanligtvis skiftar i färg mot det gula hållet. Detta anses bero på en blandning av kemiska och fysikaliska faktorer, vilket därmed gör det till ett komplext problem som berör massa & pappersindustrin. Majoriteten av litteraturen och den forskning som utförts inom området gällande eftergulning visar att de två faktorerna ljus och värme påverkar förändringen av ljusheten i högst omfattning, beroende på vilken typ av massa och process som pappret är producerat av. Smurfit Kappa i Piteå är en tillverkare av papperstypen Kraftliner och har under olika perioder noterat ostabila ljushetsvärden på grund av eftergulningen. Frida Sandin konstaterade genom sitt examensarbete hos Smurfit Kappa under 2008 att massan som bleks i en helt klorfri process är extra känslig mot värme, speciellt under längre tidsperioder. Sandin konstaterade även att lagringstemperaturen för pappersprodukter har stor betydelse, speciellt gällande avsvalningsförloppet i de nytillverkade pappersrullarna under papperstillverkning vilka kunde ta ungefär två veckor på sig att nå omgivningens temperatur. Detta arbete fortsätter på Sandins tidigare studier, samt med en litteraturstudie som grund, genom att undersöka pH:s påverkan på papper i samband med varierande temperaturer mer noggrant. Genom ett inledande faktorförsök konstaterades det att eftergulningen gynnas av högre temperaturer i samband med lägre pH värden. För att kunna få en eftergulning på en pappersprodukt inom en rimlig tid så användes en accelererad åldringsmetod, i detta arbete användes främst en metod med en temperatur på 105 °C enligt ISO standarden 5630–1. Eftergulningen inom detta arbete uttrycks i det så kallade b*-värdet vilket indikerar en färgskiftning mellan blått och gult. Ytterligare försök, bland annat i kombination med fukt, konstaterade vidare att ett surt pH starkt missgynnar stabiliteten på eftergulningen för pappersprodukter. Det observerades också att pH-värdet sjönk under experiment där pappersmassa lagrades, detta skedde mest troligt på grund av det kemiska fenomenet som kallas sur hydrolys. b*-värdet tycktes däremot vara gynnsamt av det sänkta pH-värdet. Förslagsvis så borde massan lagras vid pH runt 8 istället för 9–10 för att reducera potentiella eftergulnings-reaktioner. Det konstaterades också att kylning av papperet resulterar i en sänkning av b*-värdet, det är dock oklart vad som får detta att ske men en teori är att det är kromofora grupper som aktiveras/inaktiveras.

This paper gives a brief overview on the published and accepted standards and methods for colour photography and print lightfastness measuring and evaluating. A comparison of selected valid standards and evaluation suggestions has been made. Sample sets was produced by various photographic processes and printing techniques. Identical sample sets were used in both long-term and accelerated ageing experiment. In this thesis, the degradation speed is expressed as a formal rate constant, which was calculated from the dependence of normalized gamut volume on the exposure dose. Photographs and prints were compared on calculated lifetime basis. A failure of reciprocity law was observed, which indicates a lower credibility of estimated lifetime predictions based on accelerated ageing.

Les transistors IGBT sont les composants semi-conducteurs de puissance les plus couramment utilisés dans les fonctions de l'électronique de puissance. Ils sont fréquemment assemblés dans des modules contenant plusieurs puces et réalisant l'interconnexion à la fois électrique et thermique avec l'environnement. Dans de nombreuses applications, ces modules sont soumis à un cyclage thermique actif généré par les variations du régime de fonctionnement du système. Ceci est à l'origine de différentes dégradations d'origine thermomécaniques pouvant mener à la défaillance. Les tests de vieillissement sont l'un des moyens permettant de mieux comprendre les mécanismes de dégradations en imposant des conditions de stress connues mais également de construire des modèles de fiabilité comportementaux utiles dans l'estimation de durée de vie des systèmes.Le présent travail décrit la mise en œuvre d'une méthode de test originale destinée à des modules IGBT de la gamme 600V-200A et basée sur l'utilisation d'onduleurs fonctionnant en modulation de largeur d'impulsion. Elle exploite la variation de température de jonction provoquée par cette modulation pour générer un cyclage thermique d'une fréquence très supérieure (2Hz à 10Hz) à celles habituellement utilisées pour ce type de test. Ceci permet de réduire considérablement la durée de ces tests et d'accéder à des gammes basses de l'amplitude des cycles thermiques.Les essais de vieillissement imposent de suivre l'évolution de paramètres indicateurs afin d'estimer régulièrement l'état des composants testés et d'appliquer des conditions d'arrêt. Le paramètre utilisé dans le présent travail est la tension VCE des IGBT, qui est un bon révélateur de l'état des fils de bondings, maillons faibles de ces modules. En complément du développement de la méthode de cyclage proprement-dite, un dispositif de suivi automatique du paramètre VCE a été développé afin de limiter la durée des phases de caractérisations correspondantes. Ce dispositif permet également de mesurer la température de jonction de façon indirecte et de reconstruire le profil de température dynamique pendant le cyclage.Cet ensemble a permis d'obtenir des résultats exploitables sur une trentaine d'échantillons avec des amplitudes de cycle comprises entre 30°C et 50°C. Ils mettent en évidence un seul type de dégradation, la fissuration des attaches entre les fils de bonding et la métallisation d'émetteur avec, dans certains cas, le décollement complet du fil (lift-off). Des essais à différentes fréquences de cyclage pour la même amplitude ont été réalisés sur un groupe de ces échantillons. Si le nombre d'échantillons consacrés à comparaison n'est pas encore réellement suffisant, les résultats obtenus sont similaires et semblent donc démontrer que la fréquence de test n'impacte pas le mode de vieillissement dans la gamme de température étudiée. Cette observation est une première validation de la pertinence de la méthode proposée qui permet de réduire d'un facteur cinq à dix les durées de test. / IGBT transistors are the most used power semiconductor devices in power electronics and are often integrated in power modules to constitute basic switching functions. In various applications, IGBT power modules suffer thermal cycling (or power cycling) due to variations of operating conditions. This power cycling induces thermo mechanical stress that can lead to damages and then, to failures. Ageing tests are a means to identify and analyze the degradation mechanisms due to power cycling by imposing calibrated test conditions. In addition, their results can be used to establish empiric lifetime models that are useful for power converter designers.The present work describes the implementation of an ageing test method dedicated to IGBT modules operating in the 600V-200A range. This method takes advantage of particular operating conditions generated by pulse width modulation inverters in which the IGBT modules to be tested are introduced. The modulation induces a variation of IGBT die temperature, i.e. a power cycling, of which the frequency is significantly higher (2Hz to 10Hz) than the operating frequencies of classical test systems. By using this technique, the test length is reduced while low values of thermal amplitude can be reached.Throughout the ageing tests, the monitoring of ageing indicators is required to evaluate the sample health and to stop the operation when predefined conditions are reached. In the present work, the ageing indicator is the on-state voltage VCE across the IGBT device that is relevant in regard with wire bond degradations. Therefore, as a complement of the fast test method, an automated VCE monitoring system has been developed in order to fully take benefit of the high test-speed. In addition, this system is able to measure the junction temperature and to provide the temperature profile during the power cycling.This test bench has made possible the ageing process of three dozen of samples by applying thermal swing amplitudes in the 30°C-50°C range, that is not reachable with classical test benches operating in low frequency because of the unacceptable test length. The results show that only one kind of damage is generated by the present test conditions, i.e. the degradation of attaches between the emitter metallization and the wire bonds. In many case, complete lift-off have been observed. Some samples have been used to evaluate the influence of thermal swing frequency on the results. The latter are unchanged when the frequency varies between 2Hz and 0.2Hz, therefore it is a first validation of the fast test relevance.

Inkjet printing technology became a popular technology for printing digital photographs in the last decade. There is a big variety of both original and alternative (cheaper) inks and print media for the consumers. But there is a question if the cheaper material provides also comparable printout quality. For this reason, it is important to test the properties of such inkjet printouts. There are several ways how to test the lightfastness of the printouts: long term storage under environmental conditions, or short, accelerated ageing tests. The stability of printouts is affected by many factors, such as ink-receiving layer, ink composition, UV and visible light intensity and air pollutants concentration in the environment. Some inkjet printouts exposed to light usually undergo surprisingly fast fading, but light is not the only dangerous condition for inkjet printout. The two types of test targets printed with dyebased inkjet inks on various paper types were subjected to both accelerated test in a xenon test chamber and light and environmental pollutants long-term test in a sunny indoor corridor. The values of light intensity were continuously monitored and samples properties were regularly measured with a spectrophotometer. Another type of testing included accelerated ozone ageing of inkjet dyes. The colour gamuts and gamut volumes were calculated from collected spectral data. Total colour difference E*ab was also evaluated, its increase served as a tool for finding the formal printout degradation rate constant. It was found out that the dyes in ink-receiving layers of printouts underwent significant degradation in all tested conditions. The degradation rate depended on the type of used print media. The reciprocity behaviour of printouts was also studied. Recent inkjet printouts testing miss some actual ISO norm which should show the way of effective lightfastness evaluation. One of the main aims of this work was to find some new and alternative ways of inkjet printouts lightfastness evaluation. The method of printed inks concentration determination from the test charts spectrophotometric measurements was also proposed.

This diploma thesis deals with the impact of pollutants on colour photography made by inkjet printing technology. There are summarized basic principles of inkjet printing, composition of inks and negative factors influencing the printout quality. The ozone was studied in the experimental part, because it has the stongest degrading effect of all common pollutants. The accelerated ageing test with changing the concentration of ozone and the time of exposure was performed. The test scales were made by using two different inks. The L*a*b* values and optical densities of selected fields were calculated from the reflectance spectra of 918 colour fileds. The colour gamut and its volume were calculated from the L*a*b* values. The changes of colour gamut volume correlated with the changes of optical densities. It emerged that using the colour gamut as the instrument of evaluation of the inkjet printout dyes degradation rate is eligible and it is suitable to recommend this method for the ozone accelerated tests.

L’intégration des dispositifs électroniques de puissance dans les véhicules automobiles nécessite une connaissance approfondie de leur fiabilité. Ces éléments sont soumis à des contraintes de fatigue électrothermique de plus en plus importantes. Cette étude vise à caractériser l’évolution de composants à base de MOSFET lors de tests de fatigue accélérés et contrôlés afin de déterminer les mécanismes physiques qui conduisent à sa dégradation.Nous décrivons d'abord l’évolution technologique des composants électroniques de puissance jusqu’à la technologie de type SmartMos utilisée par Freescale Semiconductor aujourd'hui. Les outils de caractérisation microstructurale (SAM, SAT, SEM, SIM, TEM, …) sont ensuite détaillés ainsi que l'échelle spécifique pour laquelle ils sont utilisés.Le vieillissement accéléré des composants est effectué sur un banc de fatigue pour déterminer la durée de vie d'un composant selon des paramètres donnés. L'analyse complète des composants détruits a permis de conclure que la zone affectée en priorité par le cyclage électro-thermique est le métal source qui comprend la métallisation en aluminium et les fils d'amenée de courants. Ces mêmes zones sont ensuite examinées après un vieillissement contrôlé correspondant à une fraction de la durée de vie. La fatigue du composant est essentiellement caractérisée par une forte augmentation de la résistance du métal source qui engendre l’augmentation de sa résistance drain-source (RdsON). Nous avons expliqué ce phénomène par une dégradation de la métallisation qui consiste en une division des grains d'aluminium et à l’apparition de fissures le long des joints de grains.Ces caractérisations sont corrélées à une étude par éléments finis (FEM) qui permet de simuler l’augmentation et le gradient de température dans un composant pendant un cycle de vieillissement, ainsi que l’impact de l’élévation de la résistance de la métallisation source sur le comportement thermoélectrique du composant / Integration of power electronic devices in automotive applications requires a perfect knowledge of their reliability as these components are subjected to more drastic electrothermal stresses. This study aims at determining the physical mechanisms responsible for degradation and failure of modern MOSFET-based power microprocessors during accelerated and controlled fatigue tests.After a description of the recent developments in power electronics that led to today's SmartMos technology from Freescale Semiconductor, the different microstructural characterizing techniques (SAM, SAT, SEM, SIM, TEM, …) and the specific scale for which they are used are detailed.The accelerated ageing of the components were carried out on a fatigue bench to evaluate the component lifetime according to parameters such as the temperature, current and pulse durations. A complete analysis of failed components showed that the area which is primarily affected by the electro-thermal cycling is the metal source that includes aluminum metallization and connection wires. In controlled ageing tests, we showed that the drain-source resistance (Rdson) increase was due to the metal source resistance augmentation. This phenomenon is linked to the degradation of the Aluminum layer that happens through grains division and crack propagation along the grain boundaries

Le premier objectif du projet HYBUS est d’intégrer un système de stockage par supercondensateurs dans un trolleybus permettant la récupération de son énergie de freinage afin d’assurer la continuité de l’alimentation des systèmes électriques embarqués. A terme un système de stockage plus conséquent est prévu pour permettre au trolleybus une autonomie de quelques mètres. Notre travail étudie la durée de vie de ce système. Plusieurs tests de vieillissement accéléré sur les supercondensateurs ont été mis en place au laboratoire AMPERE. Ces essais ont mis en évidence que le cyclage engendrait une forte accélération de la diminution de la capacité et de l’augmentation de la résistance série. Cependant, ces variations sont partiellement réversibles lors des phases de repos où une régénération s’opère. Une méthode se basant sur les dégradations observées en cours d’utilisation et les dégradations demeurant après régénération, a permis une mise en équation de l’évolution des paramètres internes des supercondensateurs. Un test d’endurance de systèmes complets de stockage a aussi été réalisé au laboratoire. Les résultats expérimentaux montrent une hétérogénéité du vieillissement due à l’existence d’importants gradients de température entre les composants. De ce fait, une nouvelle méthodologie d’équilibrage visant à égaliser les durées de vie de chacun des supercondensateurs a été mise au point. L’étude a donc contribué à une meilleure compréhension et évaluation du vieillissement des supercondensateurs dans le but d’améliorer la durée de vie de système de stockage de ce type. Une méthode est proposée pour estimer les dégradations en fonction des facteurs majeurs du vieillissement. / The first objective of the HYBUS project is to integrate a supercapacitor storage system in a trolleybus in order to ensure the continuity of onboard electrical systems supply. The aim is to integrate an energy storage system, composed by a huge number of supercapacitors, for the recovery of the braking energy of trolleybus and allow autonomy for several meters. Our work concerns the study of the lifetime of the storage system. Several accelerated aging tests on supercapacitors were developed in the AMPERE aboratory. These tests have shown that as far as ageing are concerned; the cycling is the major responsible. However, these changes are partially reversible during the rest time when regeneration phenomena are observed. A method based on the observed damage during cycling and the damage after regeneration, leads to a formal equation for the evolution of internal parameters of supercapacitors. An endurance test of complete storage systems was also performed in the laboratory. Experimental results show the heterogeneity of aging due to the existence of significant temperature gradients between components. As a result, a new balancing strategy to equalize the lifetime of each supercapacitors has been developed. In conclusion, our study has contributed to a better comprehension and evaluation of supercapacitors aging in order to improve the lifetime of this type of energy storage system. A method for the estimation of the supercapacitor lifetime has been also proposed.

<p>U radu su sprovedena ispitivanja kvaliteta semena samooplodnih linija kukuruza stvorenih u Institutu za kukuruz &bdquo;Zemun Polje&ldquo; razliĉitih grupa zrenja i genetiĉke osnove. U laboratorijskim i poljskim uslovima utvrĊena je klijavost i vigor semena iz 2011. nakon ĉetiri godine ĉuvanja u kontrolisanim uslovima (18 &deg;C i 60% RH) i semena iz 2014. nakon godinu dana ĉuvanja na 5 &deg;C i 60% RH.<br />Cilj je bio utvrditi tolerantnost odabranih linija na niske temperature prilikom klijanja i nicanja, dugoveĉnost semena u kontrolisanim uslovima ĉuvanja, genetiĉku divergentnost linija primenom proteinskih markera i proceniti uticaj genetiĉke osnove na kvalitet semena.<br />U laboratoriji za ispitivanje semena praćeni su sledeći parametri kvaliteta: vitalnost, klijavost, energija klijanja, dužina klijanaca, vigor ispitan tetrazolium testom, hladnim testom, testom ubrzanog starenja, testom pojave primarnog korena i testom provodljivosti.<br />Primenom vigor testova na semenu dva nivoa starosti omogućena je bolja klasifikacija linija u pogledu kvaliteta, nego standardnim testom klijavosti. Rezultati rada ukazuju da su hladni test i test ubrzanog starenja najpogodniji za procenu vigora semena u laboratoriji, s tim da je hladni test bolji pokazatelj nicanja u polju.<br />Ispitivane samooplodne linije pokazale su dobru sposobnost oĉuvanja kvaliteta semena kao i visok nivo toleratnosti na niske temperature u toku klijanja i ranog porasta biljaka. Kontrolisani uslovi ĉuvanja na 18 &deg;C omogućili su da se klijavost i vigor semena u ispitivanom periodu, održi na visokom nivou.<br />Dužina vegetacije samooplodnih linija nije imala znaĉajan uticaj na klijavost i vigor semena. Kvalitet semena ispitivanih samooplodnih linija je prvenstveno bio pod uticajem genetiĉke osnove. Linije poreklom od Lancaster populacije imale su slabiji vigor u odnosu na linije BSSS i Iowa Dent porekla.<br />U radu je potvrĊeno da vigor testovi imaju važnu ulogu u ispitivanju kvaliteta semena samooplodnih linija kukuruza. Dobijeni rezultati direktno se mogu iskoristiti u oplemenjivaĉkim programima u cilju pobolj&scaron;anja klijavosti i vigora semena. Ostvareni rezultati ukazuju da su informacije o genetiĉkom poreklu samooplodnih linija važan indikator vigora semena. Pored podataka o genetiĉkom poreklu linija veliki znaĉaj ima karakterizacija putem biohemijskih markera.</p> / <p>The extensive seed quality evaluations of maize inbred lines developed at the Maize Research Institute Zemun Polje of different maturity groups and genetic background were conducted. In laboratory and field conditions germination and vigour of seed produced in 2011 and 2014 was determined, after four years of storage at 18 &deg;C, 60% RH and one year of storage at 5 &deg;C, 60% RH, respectively.<br />The objective of this research was to determine the chilling tolerance of selected inbred lines during germination and emergence, seed longevity under controlled storage conditions, genetic divergence determined by biochemical markers and to assess the impact of the genetic background on seed quality.<br />Following seed quality parameters were tested: viability, germination, seedling length and vigour examined by cold test, accelerated ageing test, tetrazolium test, radicle emergence test and conductivity test.<br />Vigour tests provided a better classification of inbred lines of different seed age in terms of quality than standard germination test. Obtained results show that cold test and accelerated aging test are the most suitable for assessing seed vigour in the laboratory, but cold test is a better indicator of field emergence.<br />Tested maize inbred lines showed good seed storability and high level of chilling tolerance during germination and early growth of plants. Controlled storage conditions at 18 &deg;C, have enabled that germination and seed vigor remains at the high level in the examined period.<br />Seed germination and vigour of maize inbred lines were not affected by length of vegetation. Seed quality was primarily influenced by genetic background of tested inbred lines. Inbred lines originating from Lancaster populations had lower vigour compared to lines with BSSS and Iowa Dent origin.<br />This research confirmed that vigor tests play an important role in seed quality testing of maize inbred lines. Results of this work can be directly used in breeding programs to improve germination and seed vigour. Achieved results indicate that information about the genetic origin of inbred lines is an important indicator of seed vigour. Finally, data emphasized the importance of inbred line characterization by biochemical markers in addition to genetic origin information.</p>

<p>Solar electricity is a promising energy technology for the future, and by using reflectors for concentrating solar radiation onto photovoltaic cells, the cost per produced kWh can be significantly reduced. The optical efficiency of a concentrating system determines the fraction of the incident energy that is transferred to the cells and depends on the optical properties of the system components. In this thesis, low-concentrating photovoltaic and photovoltaic-thermal systems with two-dimensional parabolic reflectors were studied and optimised, and a new biaxial model for the incidence angle dependence of the optical efficiency was proposed.</p><p>Concentration of light generally results in high cell temperatures, and the uneven irradiance distribution on cells with parabolic reflectors leads to high local currents and temperatures, which reduce fill-factor and voltage. Cooling the cells by means of water increases the voltage and makes it possible to utilize the thermal energy. The performance of a 4X concentrating photovoltaic-thermal system was evaluated. If operated at 50°C, this system would produce 250 kWh_electrical and 800 kWh_thermal per m² cell area and year. Optical performance can be increased by 20% by using better reflectors and anti-reflectance glazing.</p><p>Low-concentrating photovoltaic systems for façade-integration were studied and optimised for maximum annual electricity production. The optimisation was based on measured short-circuit currents versus solar altitude. Measurements were performed outdoors and in a solar simulator. It was found that the use of 3X parabolic reflectors increases the annual electricity production by more than 40%. High solar reflectance is crucial to system performance but by using a low-angle scattering reflector, the fill-factor and power are increased due to a more even irradiance on the modules.</p><p>Long-term system performance depends on the durability of the components. The optical properties and degradation of reflector materials were assessed using spectrophotometry, angular resolved scatterometry, Fresnel modelling, optical microscopy, and surface profilometry before and after ageing. The degradation of reflectors was found to be strongly dependent on material composition and environmental conditions. Back surface mirrors, all-metal reflectors, and polymer-metal laminates degraded in different ways, and therefore accelerated ageing must be tailored for testing of different types of reflector materials. However, new types of reflector laminates showed a potential for increasing the cost-effectiveness of low-concentrating solar energy systems.</p>