Les symptômes neuropsychiatriques (SNP), des perturbations comportementales et psychologiques, surviennent fréquemment dans la démence de la maladie d’Alzheimer. En plus d’être un facteur de risque d’institutionnalisation précoce et de constituer une charge pour les aidants, ils peuvent aussi être associés à un déclin cognitif accéléré ou à des troubles cognitifs plus importants lorsqu’ils surviennent dans les stades pré-démentiels des maladies (avant ou pendant le trouble cognitif léger). Considérant la diversité des résultats d’études antérieures, la relation entre ces SNP, le déclin cognitif et la survenue/évolution des maladies neurodégénératives est encore pleine de mystères. En effet, il a pu être mis en évidence que la dépression, l’apathie, ou encore l’anxiété étaient des facteurs de risques de conversion en maladie d’Alzheimer, ou de déclin cognitif accéléré chez des individus ayant un trouble cognitif léger ou une cognition normale. Ils ont aussi pu être associés à des changements des structures ou du métabolisme cérébraux, limbiques et associatifs. Cependant, le rôle et la position exacte des SNP dans le décours temporel des maladies restent incertains : conséquences de la neurodégénérescence ? Conséquence psychologique de la survenue de troubles cognitifs ? Cause de troubles cognitifs par réorientation des ressources exécutives et comportementales ? Stade prodromal des maladies ? Conséquence d’une structure de personnalité antérieure ? Ce travail propose d’aborder différentes problématiques de recherches liées aux SNP, notamment leurs associations cognitives en fonction de facteurs démographiques, psychologiques ou psychiatriques dans différents stades de déclins cognitifs ; leurs associations neurostructurelles ou métaboliques cérébrales, en devis transversal, rétrospectif ou longitudinal. L’objectif étant de conforter certaines données de la littérature sur l’impact des SNP sur les performances cognitives et leur évolution dans le vieillissement normal et pathologique, et comprendre l’apport de certaines analyses prédictives et de facteurs de risques afin d’en dégager des pistes d’applications cliniques dans une visée d’anticipation du déclin cognitif. Pour cela, différentes bases de données sont traitées afin d’extraire différents types de variables d’intérêt (démographiques, neuropsychiatriques, neuropsychologiques, neuroimagerie, statuts génétiques et diagnostiques, facteurs psychologiques…). Au total, c’est près de 5000 participants qui ont été extraits et analysés au travers des différentes bases de données. Les principaux résultats ont permis de montrer : 1) des associations SNP/performances cognitives différentes entre les femmes et les hommes ; 2) des relations neurostructurelles différentes entre les SNP et les différents stades de déclin cognitif de la maladie d’Alzheimer ; 3) le rôle prédictif des SNP dans la conversion du trouble cognitif léger en maladie d’Alzheimer expliqué par l’altération des habiletés fonctionnelles des individus ; 4) des implications de traits de personnalité dans le déclin cognitif et cérébral chez des individus développant ou non démence de type Alzheimer. Ces données consolident les résultats de la littérature et soutiennent l’utilité de certains modèles statistiques et de prédictions dans l’établissement des facteurs de risques de déclin et l’estimation de l’importance du déclin basé sur ces facteurs, à la fois chez des individus cognitivement sains, et des individus à risque de développer une démence. / Neuropsychiatric symptoms (NPS), behavioral and psychological disturbances, occur frequently in Alzheimer's dementia. In addition to being a risk factor for early institutionalization and a burden to caregivers, they may also be associated with accelerated cognitive decline or greater cognitive impairment when they occur in the pre-dementia stages of the diseases (before or during mild cognitive impairment). Considering the diversity of results of previous studies, the relationship between these NPS, cognitive decline and the occurrence/evolution of neurodegenerative diseases is still full of mysteries. Indeed, it has been shown that depression, apathy, or anxiety were risk factors for conversion to Alzheimer's disease, or for accelerated cognitive decline in individuals with mild cognitive impairment or normal cognition. They could also be associated with changes in brain, limbic and associative structures or metabolism. However, the exact role and position of NPS in the temporal course of diseases remains uncertain: consequences of neurodegeneration? Psychological consequence of the onset of cognitive disorders? Cause of cognitive disorders by redirection of executive and behavioral resources? Prodromal stage of diseases ? Consequence of a previous personality structure? This work proposes to address different research issues related to NPS, in particular their cognitive associations according to demographic, psychological or psychiatric factors in different stages of cognitive decline; their neurostructural or cerebral metabolic associations, in crosssectional, retrospective or longitudinal specifications. The objective is to confirm certain data in the literature on the impact of NPS on cognitive performance and its evolution in normal and pathological aging, and to understand the contribution of certain predictive analyses and risk factors in order to identify avenues of clinical application with a view to anticipating cognitive decline. For this purpose, different databases are processed in order to extract different types of variables of interest (demographic, neuropsychiatric, neuropsychological, neuroimaging, genetic and diagnostic status, psychological factors...). In total, nearly 5000 participants were extracted and analyzed through the different databases. The main results showed: 1) different NPS/cognitive performance associations between women and men; 2) different neurostructural relationships between NPS and different stages of cognitive decline in Alzheimer's disease; 3) the predictive role of NPS in the conversion of mild cognitive impairment to Alzheimer's disease explained by the alteration of individuals' functional abilities; 4) implications of personality traits in cognitive and brain decline in individuals developing or not dementia of the Alzheimer’s type. These data consolidate the findings of the literature and support the utility of certain statistical and predictive models in establishing risk factors for decline and estimating the magnitude of decline based on these factors, both in cognitively healthy individuals, and individuals at risk of developing dementia.

Achieving sustainable lubrication by using environmentally friendly formulated lubricants has became an essential component of the transition process from fossil-powered vehicles to electrified transportation. Mixtures, or aqueous solutions of molecules such as polyhydroxy alcohols, and glycols usually known as green lubricants make it possible to achieve low friction coefficients under different lubrication conditions, which constitutes a potential alternative to improve the tribological performance of moving parts in automotive systems, at the same time that the environmental requirements are satisfied. There is a need to improve the protection against mild-wear and micropitting offered by green-lubricants before consider using them in the transmission gear box of battery electric vehicles BEVs, where their low shear-stress resistance can potentially help to improve the vehicle efficiency. Therefore, this research work aims to gain understanding of the tribological behaviour of rolling-sliding elements under glycerol-based lubrication, with focus on assessing the influence of different glycerol-based lubricant formulations on the wear modes associated to rolling contact fatigue such as micropitting, and macropitting.  Micropitting tests were carried out by using a micropitting rig, with a roller on ring planetary configuration. The evolution of microcracks, and micropitting was studied for several glycerol-based lubricants at different slide-to-roll ratios (SRRs) 5-30%, and different load contact conditions 1.5-2.5 GPa. A comparison against a fully formulated transmission oil has been performed. A relationship between the surface damage morphology and the operating conditions has been established. The lubrication regimes of DLC coated contacts and uncoated contacts in presence of glycerol-based lubricants were investigated through the construction of 3D friction maps, and Stribeck curves in a wide range of rolling speeds, and SRR testing conditions. The capability of two different DLC coating systems to prevent micropitting onset due to rolling contact fatigue in presence of glycerol-based lubricants was studied: Cr/a-WC:H/a-C:H and a-C:Cr.  Under mixed-lubrication regime it was found that a reduction up to 51% of friction can be achieved by using glycerol-based lubricants compared to a commercial transmission oil. The initial low friction coefficients at low contact cycles was attributed to the low pressure-viscosity coefficient of the glycerol-based lubricants. Friction was even further reduced with the increasing contact cycles since glycerol aqueous solutions were found to promote mild-wear, causing a smoothing of the surface asperities and therefore an enhancement of the hydrodynamic effect due a higher lambda ratio (Λ), making possible to trigger superlubricity in the contact. Surface micro-cracking was found to decrease at low SRR values under glycerol-based lubrication contrasted to the contacts lubricated with a fully formulated transmission oil. Once microcracks were nucleated, micropitting progressed faster in the contacts lubricated with glycerol-based lubricants, while micropitting was null or significantly delayed in presence of transmission oil. With the increasing SRR surface microcracks density and micropitting was found to became higher. The reduction of microcracks density with a glycerol-glycol based lubricant was attributed to the adsorption of long glycol molecules on the steel surface that avoid the direct interaction between asperities. The faster micropitting progression was attributed to the presence of dissolved water in the contact. Thin DLC a-C:Cr coatings were shown to significantly mitigate the penetration of surface initiated pits into the steel substrate, which was translated in a lower volume loss. Local micro-delamination was found to be the main reason behind coating failure in presence of glycerol-based lubricants, as a result, pitting took place on the steel exposed areas.

Organic coatings are extensively used as protective coatings in several industries including the automotive and aircraft industries. The last few years have witnessed an increased interest in improving not only the mechanical properties but also the corrosion protection properties of organic coatings. Among the currently investigated methods of improving the performance of organic coatings is the incorporation of additives in the organic paint matrix. Vapor grown carbon nanofibers (VGCNFs) are a class of carbon fibers that are produced by catalytic dehydrogenation of a hydrocarbon at high temperatures. Depending on the method of synthesis and the post-treatment processes, the diameter of the VGCNFs is normally in the 10-300 nm range. The small size, light weight, high aspect ratio, and unique physical, thermal, mechanical, and electrical properties of VGCNF make it an ideal reinforcing filler in polymer matrix nanocomposites to enhance the mechanical properties of the pure polymeric material in high performance applications in several industries such as the automotive, aircraft, battery, sensors, catalysis, electronics, and sports industries. The main objective of the current investigation was to study the corrosion protection offered by the incorporation of VGCNFs into a commercial alkyd paint matrix applied to the surface of mild steel coupons. The corrosion protection was investigated by immersing samples in air saturated 3% NaCl solution (artificial seawater). The samples were studied by electrochemical impedance spectroscopy (EIS) along with other measurements, including electrochemical (open circuit potential, cyclic voltammetry), chemical (salt spray test), electrical conductivity, and surface analysis (SEM, AFM, optical profilometry, and nanoindentation). The study involved the investigation of the effect of the weight percent (wt %) of the VGCNF as well as the coating film thickness on the corrosion protection performance of the coated steel samples when exposed to the corrosive electrolyte. By way of contrast, the EIS behavior of steel coupons coated with a paint coating incorporating different weight percents of powdered silicon carbide (SiC) particles was also studied. The EIS spectra were used to calculated and graph several corrosion parameters for the investigated systems. At the end, the studied coatings were ranked in order of their anticorrosive properties.

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Объектом исследования являлось изучение микроструктуры и механических свойств сталей типа 32Г2ФА. На основе литературных данных и дюрометрических испытаний проведен анализ значений параметра отпуска и определен коэффициент С. Исследована микроструктура сталей после различных режимов отпуска методами электронной и оптической микроскопии. / The object of the study was the study of the microstructure and mechanical properties of steels of the 32G2FA type. On the basis of literature data and durometric tests, an analysis of the values of the tempering parameter was carried out and the coefficient C was determined. The microstructure of steels after various tempering regimes has been studied by electron and optical microscopy.

The current global scenario is such where impact on the environment is becoming a rising concern. Global automotive manufacturers have focused more towards hybrid and electric vehicles as both more aware customers and governmental legislation have begun demanding higher emission standards. One of the many ways that Volvo Car Group approaches this trend is by mild hybridization which is by assisting the combustion engine by a small electric motor and a battery pack. A smart energy management strategy is needed in order to get the most out of the benefits that hybrid electric vehicles offer. The main objective of this strategy is to utilize the electrical energy on-board in such a manner that the overall efficiency of the hybrid powertrain becomes as high as possible. The current implementation is such that the decision for using the on-board battery is non-predictive. This results in a sub-optimal utilization of the hybrid powertrain. In this thesis, a predictive energy optimization tool is developed to maximize the utility of hybridization and the practical implementation of this tool is investigated. The optimization considers both the capacity as well as the thermal loadconstraints of the battery. The developed optimization tool uses information about the route ahead together with convex optimization to produce optimal reference trajectories of the battery states. These trajectories are used in a real-time controller to determine the battery use by controlling the adjoint states in the Equivalent Consumption Minimization Strategy equation. This optimization tool is validated and compared with the baseline controller in a simulation environment based on Simulink. When perfect information about the road ahead is known, the average reduction in fuel consumption is 0.99% relative the baseline controller. Several issues occurring in the real implementation are explored, such as the limited computational speed and the length of the route ahead that can be predicted. For this reason the information input to the optimization tool is segmented and the resulting performance is investigated. For a 30 second segmentation of the future route information, the average saving in fuel consumption is 0.13% relative to the baseline controller. It is shown that the main factor limiting the amount of savings in fuel consumption is the introduction of the thermal load constraints on the battery. / Det nuvarande globala scenariot är sådant där miljöpåverkan håller på att bli en växande angelägenhet. Globala fordonstillverkare har fokuserat mer på hybrid- och elfordon, eftersom både mer medvetna kunder och statlig lagstiftning har börjat kräva högre emissionskrav. Ett av de många sätt som Volvo Car Group närmar sig denna trend är genom mild hybridisering genom att bistå förbränningsmotorn med en liten elmotor och ett batteripaket. En smart strategi för energihantering behövs för att få ut det mesta av de fördelar som hybrida elfordon erbjuder. Huvudsyftet med denna strategi är att utnyttja den elektriska energin ombord på ett sådant sätt att den totala effektiviteten hos hybriddrivlinan blir så hög som möjligt.Den nuvarande implementeringen är sådan att beslutet att använda det fordonsbaserade batteriet är inte-förutsägbart. Detta resulterar i en suboptimal användning av hybriddrivlinan. I denna avhandling är ett prediktivt Energioptimeringsverktyg utvecklat för att maximera nyttan av hybridisering och det praktiska implementerandet av detta verktyg undersöks. Optimeringen beaktar både kapaciteten och de termiska belastningsbegränsningarna hos batteriet. Det utvecklade optimeringsverktyg använder information om vägen framåt tillsammans medkonvex optimering för att producera optimala referenstrajektorier av batteritillståndet. Dessa trajektorier används i en realtidsstyrenhet för att bestämma batterianvändningen genom att kontrollera adjungerade tillstånden strategiekvationen för den ekvivalenta förbrukningsminimiseringen. Optimeringsverktyget verifieras och jämförs med den ursprungliga styrenheten i en simuleringsmiljö baserad på Simulink. När perfekt information om vägen framåt är känd, är den genomsnittliga minskningen av bränsleförbrukningen 0,99 % relativt den ursprungliga styrenheten. Flera frågor som uppstår i den verkliga implementeringen undersöks, såsom den begränsade beräkningshastigheten och längden på den väg framåt som kan förutses. Av denna anledning är segmenteras informationen till optimeringsverktyget och den resulterande prestandan undersöks. För en 30 sekunders segmentering av framtida väginformation är den genomsnittliga besparingen i bränsleförbrukningen 0,13 % i förhållande till den ursprungligastyrenheten. Resultaten visar att den viktigaste faktorn som begränsar bränsleförbrukningsbesparingen är införandet av de termiska belastningsbegränsningarna på batteriet.