Cycle-to-cycle control is a method for using feedback to improve product quality for processes that are inaccessible within a single processing cycle. This limitation stems from the impossibility or the prohibitively high cost of placing sensors and actuators that could facilitate control during, or within, the process cycle. Our previous work introduced cycle to cycle control for single input-single output systems, and here it is extended to multiple input-multiple output systems. Gain selection, stability, and process noise amplification results are developed and compared with those obtained by previous researchers, showing good agreement. The limitation of imperfect knowledge of the plant model is then imposed. This is consistent with manufacturing environments where the cost and number of tests to determine a valid process model is desired to be minimal. The implications of this limitation are modes of response that are hidden from the controller. Their effects on system performance and stability are discussed. / Singapore-MIT Alliance (SMA)

In the application of cycle-to-cycle control to manufacturing processes, the model of the process reduces to a gain matrix and a pure delay. For a general multiple input – multiple output process, this matrix shows the degree of influence each input has on each output. For a system of high order, determining this gain matrix requires excessive numbers of experiments to be performed, and thus a simplified, but non-ideal form for the gain matrix must be developed. In this paper, the model takes the form of a Gaussian distribution with experimentally determined standard deviation and scaling coefficients. Discrete die sheet metal forming, a multiple input-multiple output process with high dimensionality, is chosen as a test application. Results of the prediction capabilities of the Gaussian model, as well as those of two previously existing models, are presented. It is shown that the Gaussian distribution model does the best job of predicting the output for a given input. The model’s invariance over a set of different formed parts is also presented. However, as shown in the companion paper on cycle-to-cycle control, the errors inherent in this model will cause non-ideal performance of the resulting control system. However, this model appears to be the best form for this problem, given the limit of minimal experimentation. / Singapore-MIT Alliance (SMA)

The present study was conducted to determine whether conjugate magnitude and temporal contingencies were effective in increasing the pre-ratio pause (PRP) duration and to determine the controlling variables that govern such contingencies. It has been reported in the literature that magnitude of reinforcement, if presented contingently, is effective in controlling performance and that inserting intervals of blackout (BO), during which responding does not lead to reinforcement, virtually always leads to control of responding, even though it has not been presented contingently. The conjugate schedules experimentally arranged reinforcement such that the longer the PRP, the longer was the duration of access to reinforcement and/or the shorter was the BO, located either after reinforcement or after the response. The results of this study demonstrated that the major independent variable which controlled mean PRP duration on the various conjugate reinforcement schedules studied was the delay between the response and reinforcement. The duration of the PRP was not reliably controlled by a contingency which equated PRP duration with reinforcement duration, nor by a contingency which, through imposition of a delay to trial onset, held the local delay to reinforcement constant. Additionally, cycle-to-cycle variation in reinforcement magnitude, whether presented contingently or noncontingently on PRP duration, had no reliable effect on PRP duration when compared to FR 1. The primary effect of variation in the duration of reinforcement was to reduce the variability, not the duration, of the PRP. The results of the study are briefly discussed in terms of a number of theories. These include: the maximization account (Logan, 1960); the matching law (Herrnstein, 1970); Harzem and Harzem's (1981) theory describing the unconditioned inhibitory stimulus function of reinforcement; behavioral contrast (Reynolds, 1961); and Dews' (1981) account of the importance of a response-reinforcer contiguity relation.

La réduction des émissions de polluants et la diminution de la consommation sont deux challenges fortement liés auxquels les constructeurs automobiles doivent faire face tout en maintenant les performances des moteurs. Les nouvelles stratégies telle que la réduction de la cylindrée associée à une optimisation de la boucle d'air (forte suralimentation et recirculation de gaz brûlés) possèdent ce potentiel. Cependant elles affectent la stabilité du moteur en favorisant les variations cycle à cycle (VCC) qui correspondent à une fluctuation de la combustion d'un cycle sur l'autre. L'objectif de cette thèse est de développer une méthodologie s'appuyant sur la Simulation aux Grandes Echelles (SGE) capable de prédire les VCC d'un moteur à allumage commandé. Les prédictions sont validées grâce à une base de données expérimentale conçue à l'IFP qui leur est dédiée. Une approche graduelle est employée : l'outil numérique est tout d'abord évalué sur une configuration simplifiée de moteur à piston sans combustion, puis appliqué à un moteur à allumage commandé entraîné pour valider la prédiction de l'aérodynamique interne. Sur cette dernière configuration le couplage avec le modèle de combustion DTFLES est rajouté pour simuler deux points de fonctionnement réactifs. Chacune de ces simulations intègre un ou plusieurs points de modélisation (les tétraèdres en maillage mobile, les modèles de choc et d'allumage, et la cinétique chimique) au préalable testés sur des configurations académiques. Ce travail de recherche montre que l'approche SGE, dans un contexte de calcul massivement parallèle, est un outil prometteur dans l'étude des VCC d'un moteur à allumage commandé de conception récente. / A major challenge for the development of internal combustion engines is to improve fuel economy and to reduce pollutant emissions while maintaining or enhancing engine performances. New strategies using downsizing with high levels of exhaust gas recirculation have this potential, but can impact on the combustion stability and trigger high cycle-to-cycle variations (CCV). The objective of this thesis is to set a methodology based on Large Eddy Simulation (LES) to study CCV of a Spark-Ignition (SI) engine. A gradual approach is used : the numerical tool is first evaluated on a motored axisymmetric piston-cylinder assembly, and then applied on a motored SI engine to validate the in-cylinder aerodynamic predictions. On this last configuration, the coupling with the turbulent combustion model DTFLES is added to simulate two operating points of the indirect injection engine mode. Each of these simulations takes into account one or several modeling key points (tetrahedra with moving mesh, the modelings of shock and ignition, and chemical kinetics) previously tested in academic configurations. This research work shows that LES approach, in the context of massively parallel computing, can be used to study the CCV of a realistic SI engine.

L'amélioration des moteurs à allumage commandé représente un défi de première importance pour les ingénieurs afin de produire plus d'énergie, de consommer moins de matière première et de réduire les émissions polluantes. Les nouvelles technologies apparues ces dernières années amènent les moteurs de plus en plus proches de leurs limites de fonctionnement, favorisant ainsi des phénomènes néfastes qui doivent être contrôlés. Parmi ces phénomènes, les variations cycle-à-cycle (VCC) doivent être minimisées pour garder une performance optimale et éviter une dégradation rapide du moteur. La Simulation aux Grandes Echelles (SGE) est un outil prometteur afin de prédire numériquement les niveaux de variabilités obtenues lors du design d'un moteur (limitant ainsi les coûteuses campagnes de mesures expérimentales). Ce manuscrit s'est attaché à développer une méthodologie numérique pour la prédiction des variabilités cycliques, à simuler un nombre suffisant de cycles pour pouvoir estimer les niveaux de VCC et à valider les résultats obtenus par rapport aux résultats expérimentaux. La SGE semble capter les points de fonctionnements stable et instable étudiés. Les sources qui provoquent ces VCC ont aussi été analysées et une modification du fonctionnement du moteur a été proposée afin de réduire les VCC. / The improvement of the spark ignition engines is a major challenge for engineers in order to produce more energy, to minimize fuel consumption and to reduce the pollutant emissions. The new technologies which appear in the last years bring the engines closer to their stability limit while increasing various unwanted phenomena. Among these phenomena, cycle-to-cycle variation (CCV) need to be minimized in order to keep the performances as high as possible and avoid damages on the engines. Large Eddy Simulation (LES), which is a very promising tool in order to predict the level of CCV of a given engine, has been used in the present document to simulate a mono-cylinder spark ignition engine. The present document presented a numerical methodology for the prediction of CCV, numerous engine cycles were simulated by LES in order to validate the results in comparison to the experimental findings. The LES seems to be able to capture stable and instable (in terms of CCV) operating points of the engine. In addition, the sources of CCV were also analyzed and a modification of the engine has been proposed to reduce CCV.

Variable Valve Timing (VVT) presents a powerful tool in the relentless pursuit of efficiency improvements in the internal combustion engine. As the valves have such ultimate control over the gas exchange processes, extensive research effort in this area has shown how valve event timing can be manipulated to reduce engine pumping losses, fuel consumption and engine out emissions. Pumping losses may be significantly reduced by use of throttleless strategies, making use of intake valve duration for load control, while alternative cycles such as the Miller cycle allow modification of the effective compression ratio. More recently, the value of single valve operation in part load conditions is exploited, bringing with it the concept of asymmetric valve lifts. Work in this area found the side effect of asymmetric valve operation is a significant change in the behaviour of the in-cylinder flow structures, velocities and turbulence intensity. Work presented in this thesis exploits asymmetric valve strategies to modify the in-cylinder flow conditions. The Proper Orthogonal Decomposition (POD) is a method employed in the fluids dynamics field to facilitate the separation of coherent motion structures from the turbulence. In the presented work, the application of POD to in-cylinder flow analysis is further developed by the introduction of a novel method for identifying the POD modes representative of coherent motion and those representative of the turbulence. A POD mode correlation based technique is introduced and developed, with the resulting fields showing evidence of coherence and turbulence respectively. Experimental tests are carried out using a full length optically accessible, single cylinder research engine equipped with a fully variable valve train (FVVT) to allow full control of both valve timing and lift. In-cylinder flow is measured through the use of Particle Image Velocimetry (PIV) at several crank angle timings during the intake stroke whilst the engine is operated under a range of asymmetric valve strategies. The exhaust valves and one intake valve have their respective schedules fixed, while the second intake valve schedule is adjusted to 80\%, 60\%, 40\%, 20\%, 0\% lift. The resulting PIV fields are separated into coherent motion and turbulence using the developed technique, allowing for analysis of each constituent independently. The coherent element gives insight to large scale flows, often of the order of magnitude of the cylinder. These structures not only give a clear indication of the overall motion and allow assessment of flow characteristics such as swirl and tumble ratio, but the variation in the spatial location of these structures provides additional insight to the cyclic to cycle variation (CCV) of the flow, which would not otherwise be possible due to the inclusion of the turbulent data. Similarly, with the cyclic variation removed from the turbulent velocity field, a true account of the fluctuating velocity, u' and derived values such as the Turbulent Kinetic Energy (TKE) may be gained. Results show how manipulation of a one intake valve timing can influence both the large scale motions and the turbulence intensity. By the reduction of lift, the swirl ratio is increased almost linearly as the typical counter-rotating vortex pair becomes asymmetric, before a single vortex structure is observed in the lowest lift cases. A switching mechanism between the two is identified and found to be responsible for increased levels of CCV. With the reduction in lift, TKE is observed not only to increase, but change the spatial distribution of turbulence. Of course, the reduction in valve lift comes with the penalty of a reduced valve curtain area. However, it was identified both in literature and throughout this study that the reduction in lift did not negatively influence the engine breathing as the same trapped mass was achieved under all cases with no adjustment of manifold pressure. While literature shows both bulk motion and turbulence are key in liquid fuel break-up during the intake stroke, the mixing effects under port-injected natural gas were investigated experimentally using Laser Induced Fluorescence (LIF). The valve strategy was found to have no significant effect on the mixture distribution at the time of spark.

The human body has substantial kinetic and kinematic degrees-of-freedoms, so redundant solutions are available for the central nervous system (CNS) to perform a repetitive task. Due to these redundancies, inherent variations exist in human movement, called motor variability (MV). Current evidence suggests that MV can be beneficial, and that there is an inverse association between MV and risk of injury. To better understand how the CNS manipulates MV to reduce injury risks, we investigated the effects of individual differences, task-relevant aspects, and psychological factors as modifiers of MV. Earlier work found that experienced workers adapted more stable movements than novices in repetitive lifting tasks. To expand on this, we quantified how MV differs between experienced workers and novices in different lifting conditions (i.e., lifting asymmetry and fatigue). Three different measures (cycle-to-cycle SD, sample entropy, and the goal equivalent manifold) were used to quantify MV. In a symmetric lifting task, experienced workers had more constrained movement than novices, and experienced workers exhibited more consistent behavior in the asymmetric condition. Novices constrained their movements, and could not maintain the same level of variability in the asymmetric condition. We concluded that experienced workers adapt stable or flexible strategies depending on task difficulty. In a prolonged lifting task, both groups increased their MV to adapt to fatigue; they particularly increased variability in a direction that had no effects on their main task goal. Developing fatigue also makes it difficult for individuals maintain the main goal. Based on these results, we conclude that increasing variability is an adaptive strategy in response to fatigue. We also assessed variability in gait parameters to compare gait adaptability using a head-worn display (HWD) compared with head-down displays for visual information presentation. An effective strategy we observed for performing a cognitive task successfully during walking was to increase gait variability in the goal direction. In addition, we found that head-up walking had smaller effects on MV, suggesting that HWDs are a promising technology to reduce adverse events during gait (e.g., falls). In summary, these results suggest that MV can be a useful indicator for evaluating some occupational injury risks. / Ph. D. / Whenever an individual performs a repetitive task, we can observe variations in their movement patterns. The magnitude of these variations, which are called motor variability, may be related to the risk of injury. To better understand this relationships, we investigated how different risk factors affect the patterns of human movement. In two studies, we compared movement patterns of experienced workers and novices in a repetitive lifting task. In a simple, brief lifting task, novices had more variations in their movement patterns. However, novices did not have the same level of variation in asymmetric lifting tasks, and constrained their movement more than experienced workers. Experienced workers, though, had a similar level of variation in both simple and more difficult lifting conditions. We concluded that whether stable or flexible movement pattern are used depends on task difficulty and the level of experience. In a longer-duration lifting task, both experienced workers and novices increased variations in their movement patterns over time, and we believe that these increases were an adaptation to fatigue. In a third study, we investigated the differences between variations in walking pattern when people use different types of information display (i.e., paper, cellphone, and smart glasses). Using smart glasses had a smaller effect on movement patterns, suggesting that this technology is potentially is safer than other types of display. In summary, these results suggest that studying the variations in human movement patterns can be a useful indicator to evaluate the risk of injury.

Pour franchir les prochaines étapes réglementaires, une des solutions adoptées par les constructeurs automobiles est la dépollution à la source par des nouveaux concepts de combustion. Une piste d’étude est le moteur à charge homogène allumé par compression, le moteur HCCI. Le défi majeur est de contrôler le phasage de la combustion lors des transitions. Or, l’ozone est un additif prometteur de la combustion. La première partie de ce travail est consacrée au développement d’un modèle 0D physique de la combustion dans le moteur HCCI à l’aide d’une approche statistique basée sur une fonction de densité de probabilité (PDF) de la température. Pour cela, un modèle de variance d’enthalpie est développé. Après la validation expérimentale du modèle, il est utilisé pour développer des cartographies du moteur HCCI avec et sans ajout de l’ozone afin d’évaluer le gain apporté par cet actuateur chimique en terme de charge et régime. La deuxième partie porte sur le contrôle du phasage de combustion par ajout d’ozone. Une étude de simulation est effectuée où des lois de commandes sont appliquées sur un modèle orienté contrôle. Les résultats montrent que l’ajout d’ozone permet de contrôler cycle-à-cycle le phasage de la combustion. En parallèle, une étude expérimentale sur un banc moteur est facilitée grâce à un système d’acquisition des paramètres de combustion (Pmax, CA50) en temps réel, développé au cours de cette étude. En intégrant les lois de commande par ajout d’ozone dans le calculateur du moteur (ECU), les résultats expérimentaux montrent la possibilité de contrôler non seulement cycle-à-cycle le phasage de la combustion par ajout d’ozone lors des transitions mais aussi de stabiliser le phasage de la combustion d’un point instable. / To pass the next legislator steps, one of the alternative solutions proposed for the depollution at the source by new concepts of combustion. One of proposed solution is the Homogeneous Charge Compression Ignition (HCCI) engine. The major challenge is to control combustion phasing during transitions. Ozone is promising additive to combustion. During this work, a 0D physical model is developed based on temperature fluctuations inside the combustion chamber by using Probability Density Function (PDF) approach. For this, an enthalpy variance model is developed to be used in Probability Density Function (PDF) of temperature. This model presents a good agreement with the experiments. It is used to develop HCCI engine map with and without ozone addition in order to evaluate the benefit of using ozone in extending the map in term of charge-speed. The second part deals with control the combustion phasing by ozone addition. A Control Oriented Model (COM) coupled with control laws demonstrates the possibility to control combustion phasing cycle-to-cycle. Thereafter, an experimental test bench is developed to prove this possibility. A real time data acquisition system is developed to capture combustion parameters (Pmax, CA50). By integrating control laws into Engine Control Unit (ECU), results demonstrate not only the controllability of combustion phasing cycle-to-cycle during transitions but also to stabilize it for an instable operating point.

[EN] Internal combustion engines are in a situation in which they must be cleaner and more efficient than they have ever been. This change is motivated by the global and continuous evolution of the emissions regulations linked to their commercialization, which try to establish the path to protect the human health, and move towards more sustainable energetic models. Framed in this context, the research work developed in this PhD thesis has focused on the way to continue improving the spark ignition engines. To this end, a prototype two-stroke engine has been used, with the idea of studying the Spark Ignited combustion in lean conditions ('lean SI') and the Controlled Auto-Ignition combustion 'CAI'). In this way, the traditional 'SI' operation in stoichiometric conditions of this type of engines is replaced, looking for an improvement in fuel efficiency, and a reduction, at the same time, of the pollutant emissions. This work has been approached mainly from an experimental point of view. Firstly, different works have been performed on the engine: operation of the different combustion modes, definition of the operating strategies, and compilation of experimental data coming from the engine operation in the different regions of the engine map. And, secondly, all this data has been analyzed and studied in detail to define the strengths and weaknesses of each combustion mode applied to the different engine operating conditions. The combination of these two works has led to obtain a large amount of data about the achievable efficiencies and the emissions values obtained in each combustion mode. And, in addition, the influence on the combustion of the burned gases recirculation in the engine ('EGR'), has also been studied as a strategy to reduce emissions, and control the combustion at high loads in both combustion modes. Regarding the analytical part of the work, several problems have been detected. Firstly, the high combustion variability in this engine, and secondly, the coupling of two completely different combustion modes. These issues have generated the need to analyze the data obtained in a more detailed way, in order to get more information about the combustion process. To solve these two aspects, first, a different point of view has been raised when dealing with the combustion diagnosis, the cycle to cycle analysis, and secondly, a combustion analysis methodology has been proposed in order to allow the combustion analysis from a more detailed point of view. In this way the combustion development is studied, and thus, the differentiation between the different combustion events that take place in the engine can be studied. All this work has been useful to define the strategies to operate the whole engine map by combining the 'lean SI' and 'CAI' combustion modes. This solution, compared to the current Euro VI engines, has presented higher efficiency values complying with the established emissions limits, showing in this way, the high potential of these combustion modes applied to 'SI' engines, as well as a real possibility of its implementation in future vehicles. / [ES] Los motores de combustión interna viven un momento en el que deben ser más limpios y eficientes de lo que han sido hasta la fecha. Este cambio viene dado por el endurecimiento global y continuado de las normativas anticontaminación vinculadas a su comercialización, que tratan de establecer el camino para proteger la salud de las personas que conviven con éstos, y avanzar hacia unos modelos más sostenibles de uso de las energías disponibles. Enmarcado en este contexto, el trabajo de investigación desarrollado en esta tesis se ha centrado en continuar avanzando en el camino para la mejora de los motores de encendido provocado. Para este fin se ha empleado un motor prototipo de dos tiempos con la idea de estudiar la combustión por encendido provocado en mezclas pobres 'lean SI') y la combustión mediante el autoencendido controlado de la mezcla ('CAI'). De esta forma la operación tradicional en condiciones estequiométricas de este tipo de motores es reemplazada, en busca de una mejora en la eficiencia energética, y una reducción, al mismo tiempo, de las emisiones contaminantes. Este trabajo se ha abordado desde un punto de vista principalmente experimental. En primer lugar se ha trabajado sobre el motor, operando los diferentes modos de combustión, fijando las estrategias de operación, y obteniendo gran cantidad de datos sobre el funcionamiento del motor en las diferentes regiones del mapa motor. Y, en segundo lugar, estos datos han sido analizados y estudiados en detalle para detectar los potenciales y las debilidades de cada modo de combustión aplicado a las diferentes condiciones de funcionamiento del motor. La combinación de estos dos trabajos ha servido para obtener gran cantidad de datos sobre las eficiencias alcanzables y los valores de emisiones obtenidos en cada modo de operación. Y, adicionalmente, se ha estudiado también la influencia de la recirculación de gases quemados en el motor ('EGR') sobre la combustión, como estrategia para reducir las emisiones y controlar la combustión a altas cargas en ambos modos de operación. En cuanto a la parte analítica del trabajo, se han detectado diversos problemas. En primer lugar, lidiar con la alta variabilidad de la combustión en este motor, y en segundo lugar, el acople de dos modos de combustión totalmente diferentes. Esto ha generado la necesidad de analizar los datos obtenidos de forma que nos den algo más de información sobre la forma en que se ha desarrollado la combustión. Para dar solución a estos dos aspectos, se ha planteado un punto de vista diferente a la hora de afrontar el diagnóstico de la combustión (análisis ciclo a ciclo) y se ha propuesto una metodología de análisis de la combustión que nos permita estudiar, desde un punto de vista más detallado, la forma en que se ha desarrollado la combustión, y tratar de diferenciar así los diferentes eventos de combustión que se desarrollan en el motor. Todo este trabajo ha dado sus frutos en forma de la definición de las estrategias para operar el motor en su totalidad mediante la combinación de los modos 'lean SI' y 'CAI'. Esta solución, en comparación con los motores actuales Euro VI, ha presentado unos valores de eficiencia superiores cumpliendo con los límites establecidos de emisiones, mostrando de esta forma un elevado potencial de estos modos de combustión aplicados a los motores de encendido provocado, así como una posibilidad real de implementación en los vehículos venideros. / [CA] Els motors de combustió interna alternatius es troben a un moment en el que deuen ser mes nets i eficients que mai. Aquest canvi ve motivat per l'augment de l'exigència de les normatives reguladores d'emissions contaminants vinculades a la seua comercialització, que tracten d'establir el camí per a protegir la salut de les persones que conviuen amb aquests, i avançar cap a uns models mes sostenibles d'aprofitament de les energies disponibles. Dins d'aquest context, el treball d'investigació realitzat en aquesta tesi, ha girat al voltant de la millora dels motors d'encesa provocada. Per a aquesta finalitat, s'ha emprat un prototip de motor de dos temps amb l'idea d'estudiar la combustió per encesa provocada amb dosatges pobres 'lean SI') i la combustió mitjançant una auto-encesa provocada per les condicions termodinàmiques de la cambra de combustió ('CAI'). D'aquesta manera l'operació tradicional en condicions estequiomètriques d'aquest tipus de motors és substituïda, buscant una millora en l'eficiència energètica i una reducció al mateix temps de les emissions contaminants. Aquest treball s'ha abordat des d'un punt de vista fonamentalment experimental. En primer lloc s'ha treballat sobre el motor, operant els diferents modes de combustió, fixant les estratègies d'operació, i obtenint gran quantitat de dades sobre el funcionament del motor en les diferents regions del seu mapa d'operació. I en segon lloc, aquestes dades han sigut analitzades i estudiades en detall per a detectar els potencials i les debilitats de cada mode de combustió aplicat a les diferents condicions de funcionament del motor. La combinació d'aquests dos treballs ha servit per a obtindre gran quantitat de dades sobre les eficiències assolibles i els valors d'emissions obtinguts en cada mode d'operació. I, a més, s'ha estudiat la influència de la recirculació de gasos d'escapament al motor ('EGR') sobre la combustió, com a estratègia per a reduir les emissions contaminants i controlar la combustió a altes càrregues en els dos modes de combustió. Quant a la part analítica del treball, s'han detectat diversos problemes. En primer lloc, tractar amb l'alta variabilitat de la combustió en aquest motor, i en segon lloc, l'acoblament de dos modes de combustió totalment diferents. Açò ha generat la necessitat d'analitzar les dades obtingudes de forma que ens donen més informació sobre la forma en que s'ha desenvolupat la combustió. Per a donar solució a aquests dos aspectes, s'ha plantejat un punt de vista diferent a l'hora de realitzar el diagnòstic de la combustió (un anàlisis cicle a cicle) i s'ha proposat una metodologia d'anàlisi de la combustió que permeta estudiar, des d'un punt de vista més detallat, la forma en que s'ha desenvolupat la combustió, i tractar de diferenciar així, les diferents combustions al motor. Tot aquest treball ha donat uns resultats en forma de la definició de les estratègies per a operar el motor en la seva totalitat mitjançant la combinació dels modes de combustió 'lean SI' i 'CAI'. Aquesta solució, en comparació amb els actuals motors Euro VI, ha ofert uns valors d'eficiència superiors, acomplint amb les limitacions establertes d'emissions, mostrant d'aquesta manera un elevat potencial d'aquests modes aplicats als motors d'encesa provocada, així com una possibilitat real d'implantació en els vehicles que estan per vindre. / Valero Marco, J. (2020). Analysis of the potential of SI lean combustion and CAI combustion in a two-stroke spark-assisted gasoline engine [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/138556

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