Constraint handling is difficult in model predictive control (MPC) of linear differential inclusions (LDIs) and linear parameter varying (LPV) systems. The designer is faced with a choice of using conservative bounds that may give poor performance, or accurate ones that require heavy online computation. This thesis presents a framework to achieve a more flexible trade-off between these two extremes by using a state tube, a sequence of parametrised polyhedra that is guaranteed to contain the future state. To define controllers using a tube, one must ensure that the polyhedra are a sub-set of the region defined by constraints. Necessary and sufficient conditions for these subset relations follow from duality theory, and it is possible to apply these conditions to constrain predicted system states and inputs with only a little conservatism. This leads to a general method of MPC design for uncertain-parameter systems. The resulting controllers have strong theoretical properties, can be implemented using standard algorithms and outperform existing techniques. Crucially, the online optimisation used in the controller is a convex problem with a number of constraints and variables that increases only linearly with the length of the prediction horizon. This holds true for both LDI and LPV systems. For the latter it is possible to optimise over a class of gain-scheduled control policies to improve performance, with a similar linear increase in problem size. The framework extends to stochastic LDIs with chance constraints, for which there are efficient suboptimal methods using online sampling. Sample approximations of chance constraint-admissible sets are generally not positively invariant, which motivates the novel concept of ‘sample-admissible' sets with this property to ensure recursive feasibility when using sampling methods. The thesis concludes by introducing a simple, convex alternative to chance-constrained MPC that applies a robust bound to the time average of constraint violations in closed-loop.

We consider the solution of nonlinear optimal control problems subject to stochastic perturbations with incomplete observations. In particular, we generalize results obtained by Ito and Kunisch in [8] where they consider a receding horizon control (RHC) technique based on linearizing the problem on small intervals. The linear-quadratic optimal control problem for the resulting time-invariant (LTI) problem is then solved using the linear quadratic Gaussian (LQG) design. Here, we allow linearization about an instationary reference trajectory and thus obtain a linear time-varying (LTV) problem on each time horizon. Additionally, we apply a model predictive control (MPC) scheme which can be seen as a generalization of RHC and we allow covariance matrices of the noise processes not equal to the identity. We illustrate the MPC/LQG approach for a three dimensional reaction-diffusion system. In particular, we discuss the benefits of time-varying linearizations over time-invariant ones.

In this dissertation physical phenomena relevant to (i) an interface formed between two fluids and a solid phase (wetting line) and (ii) an interface between three fluids (triple contact line) were investigated. In the former case, the wetting line (WL) phenomena which encompass the wetting line energy (WLE) or pinning, the wetting line velocity (WLV), and the contact angle hysteresis, were studied using a micropump based on electrowetting on dielectric (EWOD). In the latter case, the interfacial phenomena such as the air film lubrication effect and the liquid free surface deformation were taken into account to explain the dual equilibrium states of water droplets on liquid free surfaces. EWOD was implemented to devise a pumping method for a continuous flow in a microchannel. An active micropump with a simple layout and no moving parts is designed and fabricated which has on demand flow on/off capability. The micropump is based on droplet/meniscus pressure gradient generated by EWOD. By altering the contact angle between liquid and solid using an electric field a pressure gradient was induced and a small droplet was pumped into the channel via a uniform flow rate. A surface tension based propellant method was introduced as a low power consumption actuation method in microfluidic devices. For an initial droplet volume of 0.3µL and a power of 12nW a constant flow rate of 0.02µL/sec was demonstrated. Sample loading on-demand could be achieved by regulating an electric potential. Unexpectedly, the flow rate of the pump was found to be constant in spite of the changes in the droplet’s radius, which directly affects the pump’s driving pressure. iv The WL phenomena were studied in details to unravel the physical concept behind the micropump constant flow rate during the operation. An interesting observation was that the shrinking input droplet changes its shape in two modes in time sequence: (i) in the first mode its contact angle decreases while its wetting area remains constant due to the pinning, (ii) in the second mode the droplet’s WL starts to move while its contact angle changes as a function of its velocity. Contact angles were measured for the droplet advancing and receding WLs at different velocities to capture a full picture of contact angle behavior due to pinning and WLV effects. These results are also relevant to the meniscus inside the channel. The changes on the contact angle caused by the presence of EWOD at the bottom of the channel were studied in detail. The EWOD based micropump was used as a platform to study the contribution of the pinning and WLV effects on its constant flow rate. The effects of the WLE on the static contact angle and the WLV on the dynamic contact angle in the pump operation were investigated. Also the effect of EWOD voltage on the magnitude and uniformity of the micropump flow rate was studied. Dynamic contact angles (as a function of pinning and WLV) were used to accurately calculate the pressure gradient between the droplet and the meniscus and estimate the flow rate. It was shown that neglecting either of these effects not only results in a considerable gap between the predicted and the measured flow rates but also in an unphysical instability in the flow rate analysis. However, when the WLE and WLV effects were fully taken into account, an excellent agreement between the predicted and the measured flow rates was obtained. v For the study of the TCL between three fluids, aqueous droplets were formed at oil-air interface and two stable configurations of (i) non-coalescent droplet and (ii) cap/bead droplet were observed. General solutions for energy and force analysis were obtained and were shown to be in good agreement with the experimental observations. Further the energy barrier obtained for transition from configuration (i) to (ii), was correlated to the droplet release height and the probability of non-coalescent droplet formation. Droplets formed on the solid surfaces and on the free surface of immiscible liquids have various applications in droplet-based microfluidic devices. This research provides an insight into their formation and manipulation.

Avec l'évolution de la technologie, l'homme a procédé à la conception de systèmes de plus en plus complexes mais aussi de plus en plus sensibles aux défauts qui peuvent les affecter. Une procédure de diagnostic contribuant au bon déroulement du processus est ainsi nécessaire. Dans ce contexte, le but de cette thèse est le diagnostic des systèmes à événements discrets modélisés par des Réseaux de Petri Étiquetés (RdPE) partiellement observables. Sous l'hypothèse que chaque défaut est modélisé par le tir d'une transition non observable, deux approches de diagnostic à base d'estimation d'état sont développées. Une première approche composée de deux étapes consiste à estimer l'ensemble des marquages de base sur un horizon élémentaire glissant. La première étape consiste à déterminer un ensemble de vecteurs candidats à partir d'une approche algébrique. La deuxième étape consiste à éliminer les solutions candidates calculées qui ne sont pas associées à une trajectoire possible du RdPE. Comme l'ensemble des marquages de base pourra aussi être important, une deuxième approche de diagnostic évitera cet écueil en n'estimant pas les marquages. Une technique de relaxation des problèmes de Programmation Linéaire en Nombres Entiers (PLNE) sur un horizon fuyant est utilisée afin d'avoir un diagnostic en temps polynomial. / With the evolution of technology, humans have made available systems increasingly complex but also increasingly sensitive to faults that may affect it. A diagnostic procedure which contributes to the smooth running of the process is thus necessary. In this context, the aim of this thesis is the diagnosis of discrete event systems modeled by partially observed Labeled Petri Nets (LPNs). Under the assumption that each defect is modeled by the firing of an unobservable transition, two diagnostic approaches based on state estimation are developed. A first approach is to estimate the set of basis markings on a sliding elementary horizon. This approach is carried out in two steps. The first step is to determine a set of candidate vectors from an algebraic approach. The second step is to eliminate the calculated candidate solutions that are not associated with a possible trajectory of the LPN. As the set of basis markings can also be huge, a second diagnostic approach will avoid this pitfall by not estimating the markings. A relaxation technique of Integer Linear Programming (ILP) problems on a receding horizon is used to have a diagnosis in polynomial time.

No description available.

This thesis presents a predictive energy management controller for long-haul hybrid trucks. In a receding horizon control framework, the vehicle speed reference, battery energy reference, and engine on/off decision are optimized over a prediction horizon. A mixed-integer quadratic program (MIQP) is formulated by performing modelling approximations and by including the binary engine on/off decision in the optimal control problem. The branch-and-bound algorithm is applied to solve this problem. Simulation results show fuel consumption reductions between 10-15%, depending on driving cycle, compared to a conventional truck. The hybrid truck without the predictive control saves significantly less. Fuel consumption is reduced by 3-8% in this case. A sensitivity analysis studies the effects on branch-and-bound iterations and fuel consumption when varying parameters related to the binary engine on/off decision. In addition, it is shown that the control strategy can maintain a safe time gap to a leading vehicle. Also, the introduction of the battery temperature state makes it possible to approximately model the dynamic battery power limitations over the prediction horizon. The main contributions of the thesis are the MIQP control problem formulation, the strategy to solve this with the branch-and-bound method, and the sensitivity analysis.

Boiling is used in a wide variety of industries, including electronics cooling, distillation, and power generation. Fundamental studies on the boiling process are needed for effective implementation. Key performance characteristics of boiling are the heat transfer coefficient, which determines the amount of heat flux that can be dissipated for a given superheat, and critical heat flux(CHF), the failure point that occurs when vapor blankets the surface. The wettability of a surface is one of the key parameters that affects boiling behavior. Wetting surfaces(e.g., hydrophilic surfaces), typically characterized by a static contact angle below 90°,have better critical heat flux due to effective rewetting, but compromised heat transfer coefficients due to increased waiting times between nucleation of each bubble. Meanwhile, nonwetting surfaces (e.g., hydrophobic surfaces), characterized by static contact angles greater than 90°, have better heat transfer coefficients due to improved nucleation characteristic, but reach critical heat flux early due to surface dry out. However, recent studies have shown that the static contact angle alone offers and incomplete, and sometimes inaccurate, description of this behavior, which is instead governed entirely by the dynamic wettability. Specifically, the receding contact angle impacts the size and contact area of bubbles forming on a surface during boiling, while the advancing contact angle determines how the bubble departs. With this more complete set of wettability descriptors, three characteristic wetting regimes define the boiling behavior: hygrophilic surfaces having advancing and receding contact angles both under 90°; hygrophobic surfaces having both these dynamic contact angles over 90°;and ambiphilic surfaces having a receding contact angle less than 90°, but an advancing contact angle greater than 90°.The goal of this thesis is to experimentally characterize and compare the behavior of boiling surfaces in each of these regimes, observe the contact line behavior, and explain the mechanisms for their differences in performance.

The aim of the thesis was to create documentation for an extensive construction modifications of sports complex including the construction of housing units near Třebíč in the small village of Třebenice in Moravia. It was necessary to cooperate with the municipality and follow its requirements for the restoration of functionality and maintenance of individual operations for which the building was intended, hence the municipality considered them necessary in the future operation of the building. The project also included the design of paved areas and fencing of the playground. The main requirement of the municipality was to build a grandstand within the already built-up area of ??the object, and therefore part of the building is being demolished. This will change the layout of the basement and move the operation of the restaurant from the basement to the first floor with a view of the playground. Football players' locker rooms will be maintained in the basement, moreover a boiler room with air conditioning, facilities for referees and a club room with hygienic facilities will be added. On the first floor, the operation of the offices will be partially maintained and separated, and there will also be more space for a hairdresser and a restaurant. The last floor will be completely removed and rebuilt with a flat roof covering only half of the area compared to the current state. Following the current state, the 2nd floor will serve for housing, but as starting apartments for young families. The risers are made of autoclaved concrete and the new masonry is made of brick blocks for precise masonry. Over the restaurant is an extensive green roof and the roof over the apartments has a classic order of layers with a stabilizing layer of gravel. The building is contact-insulated with the ETICS system using mineral wool and the final layer is made of white exterior plaster. The plinth is lined with concrete cladding. Part of the restaurant is lined with wood on the so

No description available.

Collision avoidance is an essential component of autonomous shipping. As ships begin to advance towards autonomy, developing an advisory system is one of the first steps. An advisory system with a strong collision avoidance component can help the crew act more quickly and accurately in dangerous situations. One way to avoid colission is to make the vessel stop as fast as possible. In this work, two scenarios are studied, firstly, stopping along a predefined path, and secondly, stopping within a safe area defined by surrounding obstacles. The first scenario was further worked with to formulate a real-time solution. Movements of a vessel, described in three degrees of freedom with continuous dynamics, were simulated using mathematical models of the forces acting on the ship. Nonlinear optimal control problems were formulated for each scenario and solved numerically using discretization and a direct multiple shooting method. The results for the first problem showed that the vessel could stop without much deviation from the path. Paths with different curvatures were tested, and it was shown that a slightly longer distance was traveled when the curvature of the path was greater. The results for the second problem showed that the vessel stays within the safe area and chooses a relatively straight path as the optimal way of stoping. This results in a shorter distance traveled compared to the solution of the first problem. Two different real-time approaches were formulated, firstly a receding-horizon approach and secondly a lookup-based approach. Both approaches were solved with real-time feasibility, where the receding-horizon approach gave a better solution while lookup-based approach had a shorter computational time.