Diesel engine emissions of oxides of nitrogen and particulate matter can be reduced simultaneously through the use of high levels of exhaust gas recirculation (EGR) to achieve low temperature combustion (LTC). Although the potential benefits of diesel LTC are clear, the main challenges to its practical implementation are the requirement of EGR levels that can exceed 60%, high fuel consumption, and high unburned hydrocarbon and carbon monoxide emissions. These limit the application of LTC to medium loads. In order to implement the LTC strategy in a passenger vehicle engine, a transition to conventional diesel operation is required to satisfy the expected high load demands on the engine. The investigation presented in this thesis was therefore aimed at improving the viability of the high-EGR LTC strategy for steady-state and transient operation. An experimental investigation was carried out on a single cylinder high-speed direct injection diesel engine. This thesis presents research on engine in-cylinder performance and engine-out gaseous and particulate emissions at operating conditions (i.e. EGR rate, intake pressure, fuel quantity, injection pressure) likely to be encountered by an engine during transient and steady-state operation. At selected operating points, further investigation in terms of in-cylinder spray and combustion visualization, flame temperature and soot concentration measurements provided deeper insight into the combustion and emissions phenomena. Increased intake pressure at single injection high-EGR LTC operation was investigated as a strategy to reduce the emissions of partial combustion by-products and to improve fuel economy. The higher intake pressure, although effective in reducing partial combustion by-products emissions and improving fuel economy, increased the EGR requirement to achieve LTC. A split fuel injection strategy with advanced injection timing on the other hand was effective in reducing the EGR requirement for LTC from 62% with single injection to 52% with split injections at 120 kPa (absolute) intake pressure. Unburned hydrocarbon emissions and fuel economy were particularly sensitive to intake oxygen mass fraction, and injection and dwell timings with the split injection strategy. In-cylinder soot formation and oxidation mechanisms with the split injection strategy were found to be significantly different from the single injection high-EGR LTC case. Transient simulation of an engine during combustion mode transition identified engine operating parameters on a cycle-by-cycle basis. Steady-state investigation of these test conditions provided significant insight into the combustion conditions and their effect on emissions and performance. The results from this thesis demonstrated the importance of optimizing both the air handling system performance and the fuel injection system during engine transients. The increased emissions and impaired performance due to slow response of the EGR and turbocharger systems during transitions to and from LTC modes can in part be mitigated through split injections optimized for the specific transient point. This provides a clear direction for engine developers to pursue in optimizing engine calibration when running with LTC-conventional diesel dual-mode strategies.

This thesis deals with the development and evaluation of blind discrete cosine transform-based watermarking algorithms for copyright protection of digital still images using handwritten signatures and mobile phone numbers. The new algorithms take into account the perceptual capacity of each low frequency coefficients inside the Discrete Cosine Transform (DCT) blocks before embedding the watermark information. They are suitable for grey-scale and colour images. Handwritten signatures are used instead of pseudo random numbers. The watermark is inserted in the green channel of the RGB colour images and the luminance channel of the YCrCb images. Mobile phone numbers are used as watermarks for images captured by mobile phone cameras. The information is embedded multiple-times and a shuffling scheme is applied to ensure that no spatial correlation exists between the original host image and the multiple watermark copies. Multiple embedding will increase the robustness of the watermark against attacks since each watermark will be individually reconstructed and verified before applying an averaging process. The averaging process has managed to reduce the amount of errors of the extracted information. The developed watermarking methods are shown to be robust against JPEG compression, removal attack, additive noise, cropping, scaling, small degrees of rotation, affine, contrast enhancements, low-pass, median filtering and Stirmark attacks. The algorithms have been examined using a library of approximately 40 colour images of size 512 512 with 24 bits per pixel and their grey-scale versions. Several evaluation techniques were used in the experiment with different watermarking strengths and different signature sizes. These include the peak signal to noise ratio, normalized correlation and structural similarity index measurements. The performance of the proposed algorithms has been compared to other algorithms and better invisibility qualities with stronger robustness have been achieved.

<p>Östby waterworks in the community of Kramfors has since 2003 had problems of fast clogging of the slow sand filters. As the clogging appears more often, they must be cleaned more frequently which has made the drinking water preparation difficult. Wintertime it has sometimes been impossible to clean the filters which has led to their closing and this has influenced the water quality negatively.</p><p>The waterworks is a surface waterworks which takes its raw water from the lake Sjöbysjön. The water is flocculated and filtered in a contact filter with the flocculent EKOFLOCK 91. Thereafter it is alkalinized before it reaches the outdoors placed slow sand filters. After the filters the water is alkalinized and disinfected before it reaches the customers.</p><p>This thesis work has looked into which factors influence the clogging and trials have been made in order to optimize the waterworks and thereby reduce the clogging. The raw water has been studied with aspect to biology and chemistry, the filtered water has been studied with aspect to chemistry and also the pressures in the slow sand filters have been studied.</p><p>The colour of the raw water from Sjöbysjön and its catchment area has increased since the beginning of the 90-ies and also the bio volume has increased in the lake.</p><p>The contents of aluminium before the slow sand filters are far higher than the contents after, which leads to the conclusion that aluminium is accumulated in the filters. The differential pressure over the sand bed increases with time after a cleaning. This indicates an accumulation of particles which increases with the load. Observations of the filter surface before cleaning showed that it was covered by a brown, jelly-like film. The internal resistance in the filter beds increases successively after a cleaning and one month after cleaning it is highest in the upper part of the sand bed. All this points to that flocculated aluminium is gathered in the slow sand filters, on the surface, causing clogging.</p><p>While the thesis work has been going on a process of alkalinizing before the contact filters has been reengaged and this has influenced the flocking of organic materials. When raising the pH the dose of flocculent was increased and this combined increased the amount of flocculated material. The contact filters could not bear this increased amount of flock load but showed instead a breakthrough.</p><p>In a few lab scale trials the flocking pH was varied as well as the dose flocculent to the raw water and after this the water was filtrated. A tendency was seen that the separation of aluminium, colour and turbidity increased with increasing pH and dose flocculent. At the pH 6.2 and the chemical dose of 60 g/m3 the content of aluminium, the colour and the turbidity showed the lowest values in the filtrate.</p> / <p>Vattenverket i Östby, Kramfors kommun, har sedan 2003 haft problem med för snabba igensättningar i långsamfiltren. Ju oftare de sätter igen desto mer frekvent måste de rensas vilket har försvårat dricksvattenberedningen. Vintertid har rensningar ibland inte kunnat utföras och långsamfiltren har därför stängts av vilket har påverkat vattenkvaliteten negativt.</p><p>Verket är ett ytvattenverk som tar sitt råvatten från Sjöbysjön. Vattnet flockas och filtreras i kontaktfilter med fällningskemikalien EKOFLOCK 91. Därefter mellanalkaliniseras det innan det går till de utomhus placerade långsamfiltren. Efter långsamfiltren efteralkaliniseras och desinficeras det innan det når konsumenterna.</p><p>I detta examensarbete har faktorer som påverkar igensättningarna undersökts och försök har också gjorts för att optimera driften och därmed minska igensättningarna. Råvattnet har undersökts avseende dess biologi och kemi, filtraten i verken har undersökts med avseende på deras kemi och tryckbildningar i långsamfiltren har studerats.</p><p>Färgtalet i råvattentäkten Sjöbysjön och dess tillrinningsområde har ökat sedan början av 90- talet och dessutom har biovolymen i sjön ökat.</p><p>Halterna aluminium före långsamfiltren är mycket högre än halterna efter, vilket antyder att aluminium ansamlas i filtren. Differentialtrycket över sandbädden ökar med tiden efter en rensning. Detta tyder på en ansamling av partiklar som ökar med belastningen. Observationer av filterytan innan rensning visade att den täcktes av en brun geléaktig hinna. Motståndet i filtren ökar successivt efter en rensning och är en månad efter rensning störst i den övre delen av sandbädden. Allt detta pekar på att aluminiumflock ansamlas i långsamfiltren, på ytan, och orsakar igensättningarna.</p><p>Under examensarbetets gång har en föralkalinisering återinförts i vattenverkets process och den har påverkat fällningen av det organiska materialet. Då pH höjts har också dosen fällningskemikalie ökats vilket har ökat mängden flock. Denna ökade flockmängd har kontaktfiltren inte kunnat bära utan istället släppt igenom.</p><p>I några försök i labbskala varierades fällnings-pH och dos fällningskemikalie till råvatten med en efterföljande filtrering. Tendenser som kunde ses var att avskiljningen av aluminium, färg och turbiditet ökade med ökat pH och ökad dos fällningskemikalie. Vid pH 6,2 och kemikaliedos på 60 g/m3 var aluminiumhalterna, färgen och turbiditeten som minst i filtratet.</p>

The male house sparrows has two assumed visible sexual traits which are 1) the colouration (or brightness) of the beak and 2) the size of the black badge on the bird’s throat and chest. Earlier research has shown that the testosterone concentration play an important part in determine the beak colour, with a higher testosterone concentration giving the bird a darker beak and as such making the male more attractive to females.     Even though stress has been counted for as a changing factor of phenotypes and behaviour it is not certain how vast effect stress has on different animals. This study is focusing on how and if the individuals fundamental stress level (fundamental corticosterone concentration) is affecting the morphological appearance, in this case the visible sexual traits (beak colour and badge size) and mask (an indicator of age), within the house sparrows in the Lundy Island population. In this study there was no relationship between beak colour and corticosterone concentrations, stating that beak brightness is not determined by fundamental stress. Likewise there was no relationship between the corticosterone concentrations and the size of the badge. Mask measurements in relationship to corticosterone showed no significant effect. These results indicate that there is no relationship between the corticosterone concentration in the blood and the mask size or the beak colour and badge size as visible sexual traits. / Många forskare är ense om att gråsparvshannen använder sig av två synliga karaktärsdrag för att attrahera honor. Den första är mörkhetsgraden på näbben och den andra är storleken på hannens svarta bröstlapp, placerad på hals och bröst. Tidigare forskning har visat att näbbfärgen påverkas kraftigt av hannens testosteron nivå och att en högre testosteron nivå leder till en mörkare näbb, vilket är mer attraktivt för honorna.    Även om stress har visat sig påverka både fenotyp och beteende hos många olika djurgrupper är det fortfarande oklart hur stor effekt stress har på olika djur. Denna studie fokuserar på hur och om den individuella fundamentala stressnivån (den fundamentala kortikosteron nivån) påverkar de synliga attraherande karaktärsdragen (näbbfärg och bröstlappsstorlek) hos gråsparvshannarna. I denna rapport analyseras även hannarnas masker, vilka fungerar som åldersindikatorer, i relation till de individuella kortikosteron koncentrationerna. Inget samband kunde hittas mellan näbbfärg och kortikosteron nivå hos de analyserade individerna. Likaså kunde inget samband hittas mellan kortikosteron nivån och storleken på hannens bröstlapp. Inte heller maskstorleken visade samband med kortokosteron nivån. Resultatet indikerar således att stress inte påverkar hannens sexuellt attraktiva karaktärsdrag eller mask.

Many non-human animal species use colour to signal dominance, condition or reproductive status. These signals have not previously been noted in humans. This thesis investigates the effects of skin colouration and pigmentation on the apparent health of human faces. Section 2 showed that individuals with increased fruit and vegetable and carotenoid consumption have yellower skin (Study 1) due to increased carotenoid pigmentation in the skin (Study 2). In Section 3, participants enhanced the redness, yellowness and lightness of the skin portions of colour-calibrated facial photographs to optimise healthy appearance. This suggests roles for blood (red) and carotenoid/melanin (yellow) colouration in providing perceptible cues to health. The contrast between lips and facial skin colour was not found to affect the apparent health of the faces, except in the b* (yellowness) axis, where enhanced facial yellowness caused an apparent blue tint to the lips. In Section 4 participants enhanced empirically-derived oxygenated blood colour more than deoxygenated blood colour to optimise healthy appearance. In two-dimensional trials, when both blood colour axes could be manipulated simultaneously, deoxygenated blood colour was removed and replaced with oxygenated blood colour. Oxygenated blood colouration appears to drive the preference for redness in faces. In Section 5 participants increased carotenoid colour significantly more than they increased melanin colour in both single-axis and two-dimensional trials. Carotenoid colour appears to drive the preference for yellowness in faces. In a cross-cultural study (Section 6), preferences for red and yellow in faces were unaffected by face or participant ethnicity, while African participants lightened faces more than UK participants. A preference for more redness in East Asian faces was explained by this group’s lower initial redness. The thesis concludes that pigments that provide sexually-selected signals of quality in many non-human animal species – carotenoids and oxygenated blood - also provide perceptible cues to health in human faces.

Remote sensing is a powerful tool for studying the marine environment; however, many images are contaminated by sun glint, the specular reflection of light from the water surface. Improved radiative transfer modelling could lead to better methods for estimating and correcting sunglint. This thesis explores the effect of using detailed numerical models of the sea surface when investigating the transfer of light through the atmosphere-ocean system. New numerical realisations that model both the shape and slope of the sea surface have been created; these contrast with existing radiative transfer models, where the air-water interface has slope but not elevation. Surface realisations including features on a scale from 3 mm to 200 m were created by a Fourier synthesis method, using up to date spectra of the wind-blown sea surface. The surfaces had mean square slopes and elevation variances in line with those of observed seas, for wind speeds up to 15 m/s. Ray-tracing using the new surfaces gave estimates of reflected radiance that were similar to those made using slope statistics methods, but significantly different in 41% of cases tested. The mean difference in the reflected radiance at these points was 19%, median 7%. Elevation-based surfaces give increased sideways scattering and reduced forward scattering of light incident on the sea surface. The elevation-based models have been applied to estimate pixel-pixel variation in ocean colour imagery and to simulate scenes viewed by three types of sensor. The simulations correctly estimated the size and position of the glint zone. Simulations of two ocean colour images gave a lower peak reflectance than the original values, but higher reflectance at the edge of the glint zone. The use of the simulation to test glint correction methods has been demonstrated, as have global Monte Carlo techniques for investigating sensitivity and uncertainty in sun glint correction. This work has shown that elevation-based sea surface models can be created and tested using readily-available computer hardware. The new model can be used to simulate glint in a variety of situations, giving a tool for testing glint correction methods. It could also be used for glint correction directly, by predicting the level of sun glint in a given set of conditions.

Colour and appearance of hardwood are of great importance for the interiorand furniture industry. The widespread use of transparent surface treatmentand a fashion that prescribe light colour on many species, means that deviationfrom the ideal have considerable impact on the industrial operations. Kilndrying is generally regarded as the process that has the greatest impact on thecolour of Nordic hardwood species. The lack of satisfactory explanation modelsfor many types of discoloration, however, complicates the control of the dryingprocess.This thesis is an attempt to increase the knowledge of which factors thatcontrol the appearance of some commonly found discolorations associated withdrying of beech, birch and oak. The main focus is on convection drying but alsothe influence of timber storage, pre-steaming and press drying has beeninvestigated for individual species. The studies have been conducted ascomparative studies based on design of experiments in which the colour wasdetermined using a colorimeter.Results show that reddish and dark discoloration of beech and birch duringconvective drying is mainly dependent on the temperature and time of exposurewhen the local moisture content exceeds the fibre saturation point. Theconversion of naturally occurring substances in birch into coloured compoundsis not due to active precursors created at high moisture content levels duringthe subsequent drying at low moisture content levels. Interior grey stain inbeech is caused by slow initial drying at low temperatures. Log storage in coldwinter and spring climate does not cause discoloration in beech. Birch becomeslighter when press-dried at high temperatures, resulting in a colour comparableto that of traditionally kiln dried wood. Steaming of oak before kiln dryingreduce the presence of brown discoloration, a general darkening of the woodoccurs at temperatures above 50°C.

Ce mémoire prend la forme d’une réflexion critique sur le modèle proposé par Hosler afin d’expliquer les taux quantifiés d’étain et d’arsénique dans des objets de statut métalliques Mésoaméricains provenant principalement de l’Occident mésoaméricain et couvrant les deux phases de développement de la métallurgie mésoaméricaine. Ces objets font partie de la collection du Museo Regional de Guadalajara. Plus particulièrement, ce mémoire s’intéresse aux grelots mésoaméricains puisqu’ils représentent un élément important de la métallurgie préhispanique en Mésoamérique. Cette réflexion critique soulève plusieurs considérations techniques, méthodologiques, étymologiques, iconographiques, ethnohistoriques et logiques du modèle de Hosler relativement à la couleur des alliages constituant les grelots mésoaméricains. Les paramètres sur lesquels Hosler base son modèle sont questionnables à plusieurs niveaux. Ainsi, le fait que les niveaux d’arsenic ou d’étain observés dans les alliages cupriques de biens utilitaires sont généralement inférieurs à ceux quantifiés dans les alliages cupriques usités pour la fabrication de biens de statut de la Période 2 pourrait s’expliquer par le fait qu’il s’agit de deux méthodes de fabrication distinctes ayant des contraintes techniques différentes ou que ces artéfacts ont des paramètres et des fonctions distinctes. Les limites de l’association soleil-or, lune-argent y sont également exposées et un chapitre est consacré à la sonorité. / This thesis takes the form of a critical reflection on the model proposed by Hosler to explain the levels of tin and arsenic in metallic Mesoamerican status objects coming mainly from the western part of Mesoamerica and covering both phases of the development of Mesoamerican metallurgy. These objects are part of the collection of Museo Regional de Guadalajara. In particular, this thesis focuses on Mesoamerican bells since they represent an important element of the development of pre-Hispanic metallurgy.This critical reflection raises several technical, methodological, etymological iconographic, ethnohistorical and logical concerns regarding Hosler’s model relating to the colour of the alloys making up Mesoamerican bells. The desire to obtain certain colours can not be proven based solely on the results of composition analysis. Furthermore, the parameters on which Hosler bases her model are questionable on several levels. For example, the fact that the levels of arsenic or tin observed in copper based alloys used for the fabrication of utilitarian goods are generally lower than those measured in copper alloys used for status goods from Period 2 could be explained by the differing technical constraints of two distinct fabrication methods or by the contrasting parameters and functions of the two types of artifact. The limits of the association between sun-gold and moon-silver are also exposed. A chapter is also dedicated to the sonority of the bells.

The networks of surveillance cameras installed in public places and private territories continuously record video data with the aim of detecting and preventing unlawful activities. This enhances the importance of video content analysis applications, either for real time (i.e. analytic) or post-event (i.e. forensic) analysis. In this thesis, the primary focus is on four key aspects of video content analysis, namely; 1. Moving object detection and recognition, 2. Correction of colours in the video frames and recognition of colours of moving objects, 3. Make and model recognition of vehicles and identification of their type, 4. Detection and recognition of text information in outdoor scenes. To address the first issue, a framework is presented in the first part of the thesis that efficiently detects and recognizes moving objects in videos. The framework targets the problem of object detection in the presence of complex background. The object detection part of the framework relies on background modelling technique and a novel post processing step where the contours of the foreground regions (i.e. moving object) are refined by the classification of edge segments as belonging either to the background or to the foreground region. Further, a novel feature descriptor is devised for the classification of moving objects into humans, vehicles and background. The proposed feature descriptor captures the texture information present in the silhouette of foreground objects. To address the second issue, a framework for the correction and recognition of true colours of objects in videos is presented with novel noise reduction, colour enhancement and colour recognition stages. The colour recognition stage makes use of temporal information to reliably recognize the true colours of moving objects in multiple frames. The proposed framework is specifically designed to perform robustly on videos that have poor quality because of surrounding illumination, camera sensor imperfection and artefacts due to high compression. In the third part of the thesis, a framework for vehicle make and model recognition and type identification is presented. As a part of this work, a novel feature representation technique for distinctive representation of vehicle images has emerged. The feature representation technique uses dense feature description and mid-level feature encoding scheme to capture the texture in the frontal view of the vehicles. The proposed method is insensitive to minor in-plane rotation and skew within the image. The capability of the proposed framework can be enhanced to any number of vehicle classes without re-training. Another important contribution of this work is the publication of a comprehensive up to date dataset of vehicle images to support future research in this domain. The problem of text detection and recognition in images is addressed in the last part of the thesis. A novel technique is proposed that exploits the colour information in the image for the identification of text regions. Apart from detection, the colour information is also used to segment characters from the words. The recognition of identified characters is performed using shape features and supervised learning. Finally, a lexicon based alignment procedure is adopted to finalize the recognition of strings present in word images. Extensive experiments have been conducted on benchmark datasets to analyse the performance of proposed algorithms. The results show that the proposed moving object detection and recognition technique superseded well-know baseline techniques. The proposed framework for the correction and recognition of object colours in video frames achieved all the aforementioned goals. The performance analysis of the vehicle make and model recognition framework on multiple datasets has shown the strength and reliability of the technique when used within various scenarios. Finally, the experimental results for the text detection and recognition framework on benchmark datasets have revealed the potential of the proposed scheme for accurate detection and recognition of text in the wild.

La conservation des monuments implique fréquemment une étape de substitution des parties dégradées par des pierres de tailles neuves. Cependant, la pierre d’origine est souvent indisponible, ce qui soulève la question du choix d’une pierre de remplacement compatible. La question de la compatibilité de la pierre est abordée à travers une démarche transversale considérant à la fois des critères physicochimiques et des critères d’aspect visuels. Les objectifs principaux ont été d’une part l’identification les mécanismes d’altération les plus impactants en termes de changement de couleur et d’autre part, la prise en compte du contexte visuel sur la compatibilité esthétique des matériaux de remplacement. L’étude porte sur un calcaire oolitique échantillonnée en carrière et sur des monuments bâtis à différentes époques. Il résulte que les lichens endolithiques ont un effet déterminant sur la durabilité et l’aspect à long terme de la pierre via un mécanisme protecteur d’imperméabilisation de la surface. Concernant l’aspect visuel, une méthode est proposée pour mesurer la gamme de couleur acceptable dans un monument à l’aide d’un test psychovisuel. Pour cela, une chaine de traitement d’image depuis l’acquisition jusqu'à l’affichage a été mise au point pour simuler des remplacements virtuels à partir d’images colorimetriquement calibrées. A partir d’un panel d’observateurs, un protocole de test a été conçu pour identifier la gamme de couleur indiscernable au sein d’une façade de monument. La discussion s’appuie sur des résultats préliminaires concernant la muraille de la cité médiévale d’Aigues-Mortes. / The preservation of monuments frequently involves the replacement of deteriorated stones by new ones. However, the original stone is often unavailable, which raises the question of the selection of a compatible replacement stone. In this study, the compatibility of the stone is addressed through a transverse approach considering both physicochemical and aesthetic criteria. The main aims were firstly to identify the weathering mechanisms with the greatest impact in terms of colour change and secondly to study the effect of visual context on aesthetic compatibility of replacement materials. Regarding the weathering mechanisms, the study focuses on an oolitic limestone sampled on quarry and on monuments built at different periods. It results that endolithic biological colonization determines the long-lasting durability of the stone through a waterproofing protective effect. In a second step, a methodology is proposed in order to measure the acceptable colour range in a monument using psychovisual experimentation. An image processing chain from the acquisition to the display was developed to simulate realistic virtual replacements from colorimetrically calibrated images. Based on a panel of observers, a test protocol was designed to locate color thresholds that separate a perceptible from an imperceptible replaced stone. The discussion is based on preliminary results from the Aigues-Mortes medieval city walls.