"Hot-tests" form a vital facet towards the end of the production line of modern automotive plants, where the condition of the engine is checked by running it for a short period of time, to ensure its performance under standard operating conditions. The duration of hot-tests for small engines varies from 20-75 seconds. In the conventional procedure, about 10-30 grams of lubricant (for pre-coating) is used with about 650ml of standard oil for engine testing. However, about 1-3 oz. of oil is lost per engine, as it cannot be sucked out of the crankcase after the hot tests. The loss of 1-3 oz. of oil leads to a significant loss in revenue, over the large number of engines manufactured. It also causes a potential safety and environmental hazard due to leakage of lubricant during shipping or upon first use in a particular application. The goal of this project is to conduct "no-oil" hot tests using less than 10 grams of specially formulated lubricants for pretreatment. Implementation of this procedure for conducting the hot tests in the manufacturing facility would save revenue and eliminate potential hazards mentioned above in addition to cutting down on manpower and/or machinery used for handling the engine oil. An experimental study of pre-treatment of interacting interfaces of engine components, with specially formulated lubricants, for no-oil hot tests is presented. This study includes sixteen tests performed on the production line of Tecumseh's small engine manufacturing plant. The formulated lubricants were made up of tribopolymer formers, i.e., monomers, which were used in previous tribopolymerization studies. Tribopolymerization is defined as the planned or intentional formation of protective polymeric films directly and continuously on rubbing surfaces to reduce damage and wear by the use of minor concentrations of selected compounds capable of forming polymeric films in situ. This study entailed the investigation of the anti-wear properties of the formulated lubricants on a high temperature pin-on-disk machine and subsequent selection of lubricants exhibiting superior performance for use in the engine tests. The no-oil hot-tests performed at Virginia Tech and on the assembly line exhibited the superior anti-scuffing/anti-wear properties of the specially formulated lubricants, to warrant their use on the production line in the near future. / Master of Science

Les ventilateurs ont connu des progrès technologiques considérables grâce à l'application de concepts physiologiques, à l'électronique, à l'informatique et la miniaturisation. Leurs conceptions et performances intrinsèques, en revanche, ont pu rester inégales sur certains points. L'objectif de ce travail a été d'évaluer sur un banc d'essai, avec un protocole, adapté aux problématiques soulevées en pratique clinique, tous les ventilateurs de réanimation, transport et de ventilation non invasive de façon rigoureuse et reproductible. Les résultats montrent que 1) l'erreur sur le volume réellement délivré est très fréquente et correspond facilement à 1ml/kg de volume supplémentaire ; le VT indiqué sur les ventilateurs est inférieur au VT réellement délivré ; 2) les performances des nouveaux ventilateurs ne présentent pas d'améliorations significatives par rapport aux meilleurs ventilateurs testés en 2000; les ventilateurs à turbine sont identiques ou proches des meilleurs ventilateurs conventionnels ; 3) les ventilateurs dédiés à la ventilation non invasive montrent de meilleures performances pour s'adapter à la présence de fuites ; 4) la ventilation par percussion intra-pulmonaire superposée à la ventilation conventionnelle peut réduire l'apport de l'humidification, influencer les volumes administrés et induire une pression expiratoire positive intrinsèque. Les tests sur banc montrent une grande hétérogénéité des performances. Une veille technologique semble indispensable pour évaluer tout nouveau ventilateur / The ventilators have markedly improved thanks to progress in respiratory physiology, in informatics and miniaturization. However, their intrinsic performances remain unequal. The aim was to evaluate ventilators performances on reproducible bench test studies adapted to clinical questions. Tests show that 1) the error of really delivered volume is approximately 1 ml/kg of additional volume; the tidal volume (VT) indicated on the ventilators was lower than the real delivered VT ; 2) Performances of new ventilators are comparable to the best ventilators tested in 2000 ; turbine ventilators are quite similar to best conventional ventilators ; 3) The ventilators dedicated to non invasive ventilation showed better performances to cope with leaks 4) The intrapulmonary percussive ventilation superimposed on conventional ventilation can reduce humidity, increase volumes and can generate intrinsic positive expiratory pressure. The bench tests showed a large heterogeneity of performances. A technological watch seems essential to evaluate all new ventilators

Les troubles respiratoires du sommeil, notamment le syndrome d’apnée du sommeil, représentent un problème de santé publique. Ils contribuent aux symptômes diurnes comme la somnolence sévère et sont associés à des maladies chroniques.Depuis quelques années, une variété d’appareils de traitement ventilatoire a été développée pour traiter les troubles respiratoires du sommeil, principalement les maladies liées à l’obstruction de la voie aérienne supérieure (apnée obstructive) ou à la commande centrale (apnée centrale). Ces appareils fonctionnent suivant des principes différents, en raison de leurs propres algorithmes, qui sont souvent mal connus et protégés par les fabricants. Les évaluations des appareils de ventilation sont effectuées pendant les traitements cliniques chez des patients. Il est donc difficile de comparer ces différents appareils dans les mêmes conditions à cause des variabilités inter- et intra-patient. Un banc d’essai pourrait permettre de tester les réponses des appareils dans les conditions standardisées et reproductibles.Cette thèse a consisté à construire un banc d’essai qui permet de reproduire les signaux de patients et de respecter de la physiologie humaine. La réaction du banc d’essai prend aussi en compte la réaction de l’appareil à tester sur le système, i.e., ce modèle fonctionne en « boucle fermée ». Avec le banc d’essai construit, les différentes machines de pression positive continue (PPC) autopilotée disponibles sur le marché ont été évaluées pour leurs algorithmes ainsi pour leurs modes confort. De plus, trois machines de ventilation auto-asservie (ASV) ont été soumises aux différents événements respiratoires du sommeil créés par un autre modèle d’un principe similaire. Nous avons montré que les machines de PPC autopilotée ne sont pas équivalentes pour l’efficacité du traitement et la précision des données du rapport. Les modes confort pourraient éventuellement dégrader l’efficacité du traitement de PPC si la pression thérapeutique n’est pas ajustée lors de leur introduction au traitement. Pour les machines ASV, leurs réponses ne sont pas suffisantes pour normaliser la respiration et les réglages des machines peuvent influencer l’efficacité du traitement. Les résultats pourraient compléter les données cliniques et fournir une option complémentaire pour le processus futur de certification de ces dispositifs médicaux. / Sleep disordered breathing including sleep apnea is a major public health problem. It contributes to daytime sleepiness and is associated with chronic diseases. In recent years, a variety of ventilation devices have been developed with the objective of treating sleep disorders related to the upper airway obstruction (obstructive apnea) or the central command (central apnea). These devices operate with different algorithms, which are little known and protected by the device manufacturers. Since most devices are evaluated during patient treatment, it is difficult to compare them in the same conditions due to inter- and intra-patient variability. Bench test has been proposed to evaluate the device responses in standardized and reproducible conditions. This thesis was aimed to develop a respiratory bench model able to reproduce patients’ signals and also in concordance with human physiology. The bench model can take into account the pressure responses of tested devices and works in a “closed loop” setting.With this bench model, several commercially available auto-titrating continuous positive airway pressure devices were evaluated for their auto-titration algorithms as well as their pressure-relief modes. Also, three adaptive servo-ventilation devices were evaluated by subjecting various sleep disordered breathing events that were generated by another bench model of a similar principle. We demonstrated that eleven auto-titrating continuous positive airway pressure devices were not equivalent in terms of their treatment efficacy and the data accuracy in the device report. The pressure-relief modes may attenuate the efficacy if not adjusted at the time of their introduction. The responses of adaptive servo-ventilation devices were not sufficient to normalize the breathing flow and their efficacy depended on the initial settings.The current certification process of these ventilatory devices, which focus mainly on clinical aspects, may be completed by the results of our bench.

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Ocean wave as a renewable energy source possesses great potential for solving the world energy crisis and benefit human beings. The total theoretical potential wave power on the ocean-facing coastlines of the world is around 30,000 TWh, although cannot all be adopted for generating electricity, the amount of the power can be absorbed still can occupy a large portion of the world's total energy consumption. However, multiple reasons have stopped the ocean wave energy from being widely adopted, and among those reasons, the most important one is immature of the Power Take-off (PTO) technology. In this dissertation, a self-reactive two-body wave energy point absorber that is embedded with a novel PTO using the unique mechanism of Mechanical Motion Rectifier (MMR) is investigated through design, analysis and testing to improve the energy harvesting efficiency and the reliability of the PTO. The MMR mechanism can transfer the reciprocated bi-directional movement of the ocean wave into unidirectional rotation of the generator. As a result, this mechanism brings in two advantages towards the PTO. The first advantage it possess is that the alternating stress of the PTO is changed into normal stress, hence the reliability of the components are expected to be improved significantly. The other advantage it brings in is a unique phenomenon of engagement and disengagement during the operation, which lead to a piecewise nonlinear dynamic property of the PTO. This nonlinearity of the PTO can contribute to an expanded frequency domain bandwidth and better efficiency, which are verified through both numerical simulation and in-lab experiment. During the in-lab test, the prototyped PTO achieved energy transfer efficiency as high as 81.2%, and over 40% of efficiency improvement compared with the traditional non-MMR PTO under low-speed condition, proving the previously proposed advantage. Through a more comprehensive study, the MMR PTO is further characterized and a refined dynamic model. The refined model can accurately predict the dynamic response of the PTO. The major factors that can influence the performance of the MMR PTO, which are the inertia of the PTO, the damping coefficient, and the excitation frequency, are explored through analysis and experiment comprehensively. The results show that the increase on the inertia of the PTO and excitation frequency, and decrease on the damping coefficient can lead to a longer disengagement of the PTO and can be expressed analytically. Besides the research on the PTO, the body structure of the point absorber is analyzed. Due to the low-frequency of the ocean wave excitation, usually a very large body dimension for the floating buoy of the point absorber is desired to match with that frequency. To solve this issue, a self-reactive two-body structure is designed where an additional frequency between the two interactive bodies are added to match the ocean wave frequency by adopting an additional reactive submerged body. The self-reactive two-body structure is tested in a wave to compare with the single body design. The results show that the two-body structure can successfully achieve the frequency matching function, and it can improve more than 50% of total power absorption compared with the single body design. / Doctor of Philosophy / Ocean wave as a renewable energy source possesses great potential for solving the world energy crisis and benefit human beings. The total theoretical potential wave power on the ocean-facing coastlines of the world is around 30,000 TWh, although impossible to be all transferred into electricity, the amount of the power can be absorbed still can cover a large portion of the world's total energy consumption. However, multiple reasons have stopped the ocean wave energy from being widely adopted, and among those reasons, the most important one is immature of the Power Take-off (PTO) technology. In this dissertation, a novel two body wave energy converter with a PTO using the unique mechanism of Mechanical Motion Rectifier (MMR) is investigated through design, analysis, and testing. To improve the energy harvesting efficiency and the reliability of the PTO, the dissertation induced a mechanical PTO that uses MMR mechanism which can transfer the reciprocated bi-directional movement of the ocean wave into unidirectional rotation of the generator. This mechanism brings in a unique phenomenon of engagement and disengagement and a piecewise nonlinear dynamic property into the PTO. Through a comprehensive study, the MMR PTO is further characterized and a refined dynamic model that can accurately predict the dynamic response of the PTO is established. The major factors that can influence the performance of the MMR PTO are explored and discussed both analytically and experimentally. Moreover, as it has been theoretically hypothesis that using a two-body structure for designing the point absorbers can help it to achieve a frequency tuning effect for it to better match with the excitation frequency of the ocean wave, it lacks experimental verification. In this dissertation, a scaled two-body point absorber prototype is developed and put into a wave tank to compare with the single body structure. The test results show that through the use of two-body structure and by designing the mass ratio between the two bodies properly, the point absorber can successfully match the excitation frequency of the wave. The highest power capture width ratio (CWR) achieved during the test is 58.7%, which exceeds the results of similar prototypes, proving the advantage of the proposed design.

Les Systèmes Solaires Combinés (SSC), qui répondent aux besoins d'Eau Chaude Sanitaire (ECS) et de chauffage d'un bâtiment, peuvent réaliser des économies d'énergie conséquentes. Cependant, leurs performances dépendent énormément de leur conception, de leur installation et surtout de l'environnement énergétique auquel ils sont confrontés (c'est-à-dire les besoins thermiques du bâtiment et les ressources solaire). A ce jour, il est impossible de prédire l'économie d'énergie qu'un SSC permettrait de réaliser. Il n'existe aucun test normatif permettant la caractérisation des performances des SSC, ce qui pénalise le développement de son marché. La méthode SCSPT (Short Cycle System Performance Test) a pour objectif d'évaluer les performances annuelles des SSC à partir d'un test de 12 jours sur banc d'essai thermique semi-virtuel. Sa particularité est de considérer chaque système comme un unique ensemble ce qui permet, contrairement aux méthodes de type « composant », de prendre en compte les vraies interactions entre les éléments des SSC lors de leur test. Elle montre de très bons résultats mais ceux-ci sont limités à la prédiction des performances du système pour le seul environnement énergétique adopté lors du test. Ces travaux de recherche proposent une amélioration de la procédure SCSPT en lui ajoutant une étape d'identification d'un modèle générique de SSC à partir de données expérimentales. De cette manière, le modèle identifié pourrait simuler le comportement du SSC testé sur différentes séquences annuelles pour n'importe quel environnement énergétique et ainsi caractériser ses performances (à l'aide de la méthode FSC par exemple). L'architecture proposée pour ce modèle est du type « Boite Grise ». Elle mêle une partie « Boite Blanche » composée d'équations physiques caractéristiques de certains éléments du SSC et une partie « Boite Noire » constituée principalement d'un réseau de neurones artificiels. Une procédure complète est conçue pour entrainer et sélectionner un modèle correspondant aux SSC à partir des données de leur test sur banc d'essai semi-virtuel. Cette approche a été validée numériquement grâce à des simulations de trois modèles détaillés de SSC sous TRNSYS. En comparant leurs résultats annuels avec ceux des modèles « Boites Grises » entrainés à partir d'une séquence 12 jours, ces derniers sont capables de prédire la consommation en énergie d'appoint de manière très précise pour 27 environnements énergétiques différents. L'application concrète de cette nouvelle procédure a été réalisée expérimentalement sur deux SSC réels. Elle a confirmé que l'approche était pertinente et cohérente. Elle a également permis d'identifier quelques améliorations pour que la méthode soit totalement opérationnelle. Ce travaux offrent une base pour avancer dans l'élaboration d'une méthode complète et fiable de caractérisation des SSC qui pourraient conduire à une nouvelle procédure de normalisation (et d'envisager un étiquetage énergétique des SSC. / Solar Combi Systems (SCS) can be very efficient at reducing heat energy bill of a house but their performances depend on the environment they are working in (type of climate and thermal quality of the building). Currently it is impossible to predict how much energy a SCS would save before its installation. There is no standard test to characterize SCS performances and this curbs its market development. The Short Cycle System Performance Test (SCSPT), that is being developed at the French National Institute of Solar Energy (INES, Chambery, France), aims to evaluate SCS annual performance from a test on a semi-virtual test bench. Its special feature is to test the whole system as only one part, unlike “component testing” which can't consider real interaction between combisystems components. The SCSPT method shows good results but performance prediction is limited to only one environment (i.e. one set of system sizing, type of climate and building thermal quality, corresponding with the test). This work proposes an improvement of the SCSPT procedure by identifying a global SCS model from the test data. In this way, the identified model would be able to simulate the tested SCS behaviour in any environment and thus to characterize its performances. The proposed model to identify is a “grey box” model, mixing a “white box” model composed of known physical equations and a “black box” model, which is an Artificial Neural Network (ANN). A complete process is developed to train and select a relevant global SCS model from such a test on semi-virtual test bench. This approach has been validated through numerical simulations of three detailed SCS models. Compared to their annual results, “grey box” SCS models trained from a twelve days sequence are able to predict energy consumption with a good precision for 27 different environments. Concrete experimentations of this procedure have been applied to two real systems. They have confirmed that the approach is pertinent and revealed some points to improve in order to get it totally operational. This work offers major basis to get ahead with a complete method to characterize SCS that could lead to develop a standardization method from performance evaluation (and eventually complete the European norm EN 15316 for instance) and to plan a combisystems performance labelling.

Le syndrome d’apnée obstructive du sommeil affecte 6% à 17% de la population adulte. Le traitement de référence est la ventilation nocturne par une pression positive continue (PPC) fixe ou autopilotée afin de maintenir les voies aériennes ouvertes. L’efficacité de traitement des PPC autopilotées dépend des algorithmes et technologies pour détecter et qualifier les événements respiratoiresDes bancs d’essai ont été créés pour évaluer les PPC autopilotées en conditions comparables, en simulant des scénarios respiratoires composés de chaînes répétitives d’événements respiratoires. Les profils respiratoires simulés par les bancs d’essai précédents sont standardisés et simplifiés par rapport au profil respiratoire du patient.Pour tendre vers des essais plus réalistes, un nouveau banc d’essai physiologique permettant de reproduire automatiquement les profiles respiratoires à partir des données polygraphiques a été créé pendant cette thèse. Il a été validé en évaluant la simulation de scénarios respiratoires de différents phénotypes issus de 12 patients.Via ce banc d’essai, la précision de l’index d’apnée-hypopnée (IAH) résiduel fourni par PPC a été évalué, en comparant les IAH déterminés par 4 dispositifs de PPC (AirSense 10, DreamStation Auto, S.Box et Prisma 20A) avec ceux de polygraphie. Les résultats ont permis de quantifier les différences d’IAH afin d’aider les médecin à en tenir compte. / Obstructive sleep apnea syndrome affects 6% to 17% of adult population. The reference treatment is nocturnal ventilation via an either fixed or auto-titrating positive airway pressure (APAP) to maintain upper airway (UA) open. Treatment efficiency of APAP depends greatly on algorithms and technologies used for detecting and characterizing disordered breathing events (linked to UA obstruction or central command).Bench tests have been developed to evaluate APAP devices under the same conditions, by simulating respiratory scenarios composed of a repetitive string of several disordered breathing events registered from apneic patients or artificially designed.Therefore, breathing profiles simulated on benches are standardized and simplified, in comparison with patients’. To improve this disadvantage, a new physiological bench, which enables reproducing automatically a specific patient breathing profile from its polygraph recordings, has been created. It has been validated by simulating various breathing profiles issuing from 12 patients of different pathological phenotypes.Through this new bench, the accuracy of residual apnea hypopnea indices (AHI) determined by 4 APAP devices (AirSense 10, DreamStation Auto, S.Box and Prisma 20A) has also been investigated in comparison with polygraph scorings. The results would help physicians in clinical practice thanks to the quantification of AHI discrepancies between manufacturers.