<p>Scania är en välkänd tillverkare av tunga lastfordon och bussar. De profilerar sig som det presigefyllda valet med hög teknologinivå. För att kunna leda utvecklingen av nya funktioner och motorer måste många tester av alla system i dessa fordon göras. Till detta används provceller speciellt ordnade för specifika lastbilskomponenter och många av dessa komponenter behöver en yttre kylning under drift varför flera av provcellerna har reglerade kylsystem. Vid uppgradering av kylsystem eller nybyggnation av provceller med kylsystem finns en önskan att kunna simulera och göra tester av kylsystemet innan det faktiska kylsystemet finns på plats, för att säkerställa prestandan innan någon investering görs. Detta examensarbete går ut på att genom att skapa vissa basmodeller för komponenter i kylsystem, möjliggöra simulering av godtyckliga kylsystem för utvärdering av olika reglerstrategier, designer och deras prestanda. Vid framtagning av modellerna användes mestadels fysikalisk modellering men även rent praktiska modeller för att fylla en funktion existerar. Det resulterande modellbiblioteket klarar av att visa dynamiska effekter mycket bra men dess statiska träffsäkerhet är inte lika exakt. Dynamiken är dock det viktiga och svårt att få fram på andra sätt, varför modellbiblioteket kan vara användbart vid bedömningar om reglerstrategier och prestanda.</p> / <p>Scania is a wellknown manufacturer of heavy transport vehicles such as trucks and buses. Their profile is to be the prestigeous choice with a high level of technology. To maintain the leading position in development of new functionality and engines, substantial testing is nessecary. This is accomplished by using testbeds specialized for different components and purposes. Many of these components need external cooling during operation which is why a cooling system is present in a large number of testbeds. When new testbeds are to be constructed or an old cooling system is to be redesigned, there is a desire to be able to simulate and run tests of the cooling system before the actual cooling system is in place, to make sure performance is at a high enough level, before any investment is made. The task in this master thesis is to construct, in a matlab and simulink environment, a set of base models for cooling system components. With this set, arbitrary cooling systems can be constructed and simulated to evaluate different designes, control strategies and performance. Physical modelling was the most common method when constucting the base models though some models have a pure practical function. The resulting model library is able to, when put together to a complete cooling system, show dynamic behaviour correctly but static accuracy is a bit off. When judging a new control strategy, dynamic behaviour is the most important aspect, and also the most difficult to get elsewhere, which is why the model library can still be very useful.</p>

<p>Soot and radiation play an important role when designing practical combustion devices, and great efforts have been put into developing models which describe soot formation and oxidation. The Eddy Dissipation Concept (EDC) has proven to describe turbulent combustion well, and has the flexibility to describe chemical kinetics in a detailed manner. The aim of this work is to study how the EDC handles soot models based on a detailed representation of the gas-phase chemical kinetics.</p><p>Two versions of a semi-empirical soot model is used in conjunction with the EDC. Concentrations of various intermediate species are used as input to the soot models.</p><p>The implementation of the new soot models is discussed in relation to the previous implementation of a less detailed soot model. To assure that the interaction between soot and the gas-phase species is represented correctly, the soot models are implemented with a two-way coupling of soot and gas-phase kinetics.</p><p>Soot is a good radiator. In a sooting flame a substantial amount of energy will be transferred to the surroundings by thermal radiation. This transfer of energy will alter the temperature field of the flame and the change in temperature will affect the kinetics of soot and gas-phase chemistry. To simulate sooting flames correctly, it was therefore necessary to include a radiation model.</p><p>To validate the coupled models of turbulence, combustion, soot, and radiation two different turbulent flames were simulated. One turbulent jet flame of methane and one turbulent jet flame of ethylene. For both flames the computed results were compared with measured values.</p><p>Several aspects of the simulations are studied and discussed, such as the effect of the two-way coupling of soot and gas-phase kinetics on both soot yield and gas-phase composition, and the importance of a suitable radiation model.</p><p>The two-way coupling of soot and gas phase kinetics is shown to have a positive effect on the computed soot volume fractions, and the results are considered to be encouraging. The work has demonstrated that the EDC has the capacity to handle different types of chemical reaction mechanisms, such as mechanisms for gas-phase combustion and soot kinetics, without modification.</p>

<p>The contributions of this thesis fall naturally into two main categories: Part I: Feedback control of fluid flows, and; Part II: Modelling and control of marine structures.</p><p><b>Main Con tributions of Part I</b></p><p>Part I presents new results on stabilization (for the purpose of drag reduction or vortex shedding suppression) and destabilization (for the purpose of mixing) of channel, pipe and cylinder flows. In order to provide a stand-alone reference on this topic, the thesis also contains a comprehensive review of the research carried out in this field over the last decade or so, along with introductory chapters on fluid mechanics and control theory. The review also serves the purpose of placing the contributions by the author into the wider context of the field. The contributions by the author are the following:</p><p><b>Section 4.3.1:</b> A new boundary feedback control law for stabilization of the parabolic equilibrium flow in 2D channel flow is derived using Lyapunov stability theory. The controller uses pressure measurements taken on the channel wall, and applies actuation in the form of wall transpiration, that is, suction and blowing of fluid across the wall. Although the analysis is valid for small Reynolds numbers, only, simulations indicate that the control is very effcient in stabilizing the flow at Reynolds numbers several orders of magnitude higher. The pressure-based control law performed much better than other Lyapunov-based control laws studied.</p><p><b>Section 4.3.3: </b>The simple pressure-based control law derived in Section 4.3.1 is generalized to the 3D pipe flow. As for the 2D channel flow, the analysis is valid for small Reynolds numbers, only.</p><p><b>Section 4.3.4: </b>The pressure-based feedback control law derived in Section 4.3.1 for the 2D channel flow results in flow transients with instantaneous drag far lower than that of the corresponding laminar flow. In fact, for the first time, instantaneous total drag in a constant-mass- flow 2D channel flow is driven to negative levels. The physical mechanisms by which this phenomenon occur is explained, and the possibility of achieving sustained drag reductions to below the laminar level by initiating such low-drag transients on a periodic basis is explored. The results add to the evidence that the laminar ow represents a fundamental limit to the drag reduction achievable by wall transpiration.</p><p><b>Section 4.4:</b> A state feedback controller that achieves global asymptotic stabilization of a nonlinear Ginzburg-Landau model of vortex shedding from bluff bodies is designed using backstepping. Stabilization is obtained in two steps. First, the upstream and downstream parts of the system are shown to exhibit the inputto- state stability property with respect to certain boundary input terms governed by the core flow in the vicinity of the bluff body. Second, a finite difference approximation of arbitrary order of the core flow is stabilized using the backstepping method. Consequently, all the states in the core flow are driven to zero, including the boundary input terms of the upstream and downstream subsystems. The control design is valid for any Reynolds number, and simulations demonstrate its performance.</p><p><b>Section 5.2:</b> For thefirst time, active feedback control is used to enhance mixing by exploiting the natural tendency in the flow to mix. By applying the pressurebased feedback control law derived for stabilizing the 2D channel flow in Section 4.3.1, with the sign of the input reversed, enhanced instability of the parabolic equilibrium flow is obtained, which leads rapidly to highly complex flow patterns. The mixing enhancement is quantified using various diagnostic tools.</p><p><b>Section 5.3: </b>A Lyapunov based boundary feedback controller for achieving mixing in a 3D pipe flow governed by the Navier-Stokes equation is designed. It is shown that the control law maximizes a measure of mixing that incorporates stretching and folding of material elemen ts, while at the same time minim izing the control effort and the sensing effort. The penalty on sensing results in a static output- feedback control law (rather than full-state feedback). A lower bound on the gain from the control effort to the mixing measure is also deriv ed. For the openloop system, input/output-to-state stability properties are established, which show a form of detectability of mixing in the interior of the pipe from the chosen outputs on the wall. The effectiveness of the optimal control in achieving mixing enhancement is demonstrated in numerical sim ulations. Simulation results also show that the spatial changes in the control velocity are smooth and small, promising that a low number of actuators will suffice in practice.</p><p><b>Section 5.4: </b>Motivated by the mixing results for channels and pipes in Sections 5.2 and 5.3, a simulation study that investigates the feasibility of enhancing particle dispersion in the wake of a circular cylinder is carried out. For a subcritical case, vortex shedding is successfully provoked using feedback.</p><p><b>Main Contributions of Part II</b></p><p>Part II deals with modelling and control of slender marine structures and marine vessels.</p><p><b>Chapter 8:</b> A new finite element model for a cable suspended in water is developed. Global existence and uniqueness of solutions of the truncated system is shown for a slightly simplified equation describing the motion of a cable with negligible added mass and supported by fixed end-points. Based on this, along with well known results on local existence and uniqueness of solutions for symmetrizable hyperbolic systems, a global result for the initial-boundary value problem is conjectured. The FEM model for the cable is assembled to give a model of a multi-cable mooring system, whic h, in turn, is coupled to a rigid body model of the floating vessel. The result is a coupled dynamical model of a moored v essel, which can be applied to applications such as turret-based moored ships, or tension leg platforms. As a simple application of the sim ulator, controlling the line tensions dynamically as an additional means of station keeping is explored.</p><p><b>Chapter 9: </b>Output feedback tracking control laws for a class of Euler-Lagrange systems subject to nonlinear dissipative loads are designed. By imposing a monotone damping condition on the nonlinearities of the unmeasured states, the common restriction that the nonlinearities be globally Lipschitz is removed. The proposed observer-controller scheme renders the origin of the error dynamics uniformly globally asymptotically stable, in the general case. Under certain additional assumptions, the result continue to hold for a simplified control law that is less sensitive to noise and unmodeled phenomena.</p>

<p>Många svenska kommuner har idag problem med överbelastade avloppsledningssystem. Det kan bland annat resultera i källaröversvämningar i närbelägna fastigheter, överbelastade reningsverk eller bräddningar till recipienten. För att motverka dessa effekter kan olika åtgärder vidtas. Åtgärderna kan vara olika lämpliga beroende på typ av område och kostnaderna för genomförandet kan variera kraftigt och ha olika miljöpåverkan. Detta innebär att det är viktigt att väga samman effektiviteten av olika åtgärder, deras miljöpåverkan, kundnytta och kostnad.</p><p>Syftet med examensarbetet var att med hjälp av ett hydrauliskt modelleringsverktyg (PCSWMM) studera ett antal typområden och ta fram en förenklad modell. Modellen ska enkelt kunna anpassas till olika områden och ge en översiktlig bild av situationen i områdets ledningssystem. Därmed kan eventuella överbelastningsproblem lokaliseras och en kostnadseffektiv lösning testas.</p><p>En hydraulisk modell utvecklades för Viksängsvägens avrinningsområde i Södertälje kommun. Det är ett äldre område med underdimensionerade ledningar vilket orsakar problem vid hård belastning. Effekten av olika åtgärder testades i modellen och en kostnadsanalys gjordes för att utreda vilken åtgärd som var mest kostnadseffektiv.</p><p>En grenad modell visade sig ge bäst beskrivning av Viksängsvägens avrinningsområde. Det var en förenklad modell som gick relativt snabbt att sätta upp för ett nytt område och som tog hänsyn till avrinningsvolym, ledningskapacitet och ledningssystemets struktur. Modellen kräver dock en del information om ledningssystemets uppbyggnad och de hårdgjorda ytornas fördelning över området.</p><p>Den åtgärd som rekommenderades för Viksängsvägens avrinningsområde var att bygga utjämningsmagasin i anslutning till Viksängsvägen. Detta för att kostnaden var relativt liten jämfört med andra åtgärder samt för de positiva effekter åtgärden har på miljön och människorna som bor och vistas i området.</p>

The contributions of this thesis fall naturally into two main categories: Part I: Feedback control of fluid flows, and; Part II: Modelling and control of marine structures. <b>Main Con tributions of Part I</b> Part I presents new results on stabilization (for the purpose of drag reduction or vortex shedding suppression) and destabilization (for the purpose of mixing) of channel, pipe and cylinder flows. In order to provide a stand-alone reference on this topic, the thesis also contains a comprehensive review of the research carried out in this field over the last decade or so, along with introductory chapters on fluid mechanics and control theory. The review also serves the purpose of placing the contributions by the author into the wider context of the field. The contributions by the author are the following: <b>Section 4.3.1:</b> A new boundary feedback control law for stabilization of the parabolic equilibrium flow in 2D channel flow is derived using Lyapunov stability theory. The controller uses pressure measurements taken on the channel wall, and applies actuation in the form of wall transpiration, that is, suction and blowing of fluid across the wall. Although the analysis is valid for small Reynolds numbers, only, simulations indicate that the control is very effcient in stabilizing the flow at Reynolds numbers several orders of magnitude higher. The pressure-based control law performed much better than other Lyapunov-based control laws studied. <b>Section 4.3.3: </b>The simple pressure-based control law derived in Section 4.3.1 is generalized to the 3D pipe flow. As for the 2D channel flow, the analysis is valid for small Reynolds numbers, only. <b>Section 4.3.4: </b>The pressure-based feedback control law derived in Section 4.3.1 for the 2D channel flow results in flow transients with instantaneous drag far lower than that of the corresponding laminar flow. In fact, for the first time, instantaneous total drag in a constant-mass- flow 2D channel flow is driven to negative levels. The physical mechanisms by which this phenomenon occur is explained, and the possibility of achieving sustained drag reductions to below the laminar level by initiating such low-drag transients on a periodic basis is explored. The results add to the evidence that the laminar ow represents a fundamental limit to the drag reduction achievable by wall transpiration. <b>Section 4.4:</b> A state feedback controller that achieves global asymptotic stabilization of a nonlinear Ginzburg-Landau model of vortex shedding from bluff bodies is designed using backstepping. Stabilization is obtained in two steps. First, the upstream and downstream parts of the system are shown to exhibit the inputto- state stability property with respect to certain boundary input terms governed by the core flow in the vicinity of the bluff body. Second, a finite difference approximation of arbitrary order of the core flow is stabilized using the backstepping method. Consequently, all the states in the core flow are driven to zero, including the boundary input terms of the upstream and downstream subsystems. The control design is valid for any Reynolds number, and simulations demonstrate its performance. <b>Section 5.2:</b> For thefirst time, active feedback control is used to enhance mixing by exploiting the natural tendency in the flow to mix. By applying the pressurebased feedback control law derived for stabilizing the 2D channel flow in Section 4.3.1, with the sign of the input reversed, enhanced instability of the parabolic equilibrium flow is obtained, which leads rapidly to highly complex flow patterns. The mixing enhancement is quantified using various diagnostic tools. <b>Section 5.3: </b>A Lyapunov based boundary feedback controller for achieving mixing in a 3D pipe flow governed by the Navier-Stokes equation is designed. It is shown that the control law maximizes a measure of mixing that incorporates stretching and folding of material elemen ts, while at the same time minim izing the control effort and the sensing effort. The penalty on sensing results in a static output- feedback control law (rather than full-state feedback). A lower bound on the gain from the control effort to the mixing measure is also deriv ed. For the openloop system, input/output-to-state stability properties are established, which show a form of detectability of mixing in the interior of the pipe from the chosen outputs on the wall. The effectiveness of the optimal control in achieving mixing enhancement is demonstrated in numerical sim ulations. Simulation results also show that the spatial changes in the control velocity are smooth and small, promising that a low number of actuators will suffice in practice. <b>Section 5.4: </b>Motivated by the mixing results for channels and pipes in Sections 5.2 and 5.3, a simulation study that investigates the feasibility of enhancing particle dispersion in the wake of a circular cylinder is carried out. For a subcritical case, vortex shedding is successfully provoked using feedback. <b>Main Contributions of Part II</b> Part II deals with modelling and control of slender marine structures and marine vessels. <b>Chapter 8:</b> A new finite element model for a cable suspended in water is developed. Global existence and uniqueness of solutions of the truncated system is shown for a slightly simplified equation describing the motion of a cable with negligible added mass and supported by fixed end-points. Based on this, along with well known results on local existence and uniqueness of solutions for symmetrizable hyperbolic systems, a global result for the initial-boundary value problem is conjectured. The FEM model for the cable is assembled to give a model of a multi-cable mooring system, whic h, in turn, is coupled to a rigid body model of the floating vessel. The result is a coupled dynamical model of a moored v essel, which can be applied to applications such as turret-based moored ships, or tension leg platforms. As a simple application of the sim ulator, controlling the line tensions dynamically as an additional means of station keeping is explored. <b>Chapter 9: </b>Output feedback tracking control laws for a class of Euler-Lagrange systems subject to nonlinear dissipative loads are designed. By imposing a monotone damping condition on the nonlinearities of the unmeasured states, the common restriction that the nonlinearities be globally Lipschitz is removed. The proposed observer-controller scheme renders the origin of the error dynamics uniformly globally asymptotically stable, in the general case. Under certain additional assumptions, the result continue to hold for a simplified control law that is less sensitive to noise and unmodeled phenomena.

Soot and radiation play an important role when designing practical combustion devices, and great efforts have been put into developing models which describe soot formation and oxidation. The Eddy Dissipation Concept (EDC) has proven to describe turbulent combustion well, and has the flexibility to describe chemical kinetics in a detailed manner. The aim of this work is to study how the EDC handles soot models based on a detailed representation of the gas-phase chemical kinetics. Two versions of a semi-empirical soot model is used in conjunction with the EDC. Concentrations of various intermediate species are used as input to the soot models. The implementation of the new soot models is discussed in relation to the previous implementation of a less detailed soot model. To assure that the interaction between soot and the gas-phase species is represented correctly, the soot models are implemented with a two-way coupling of soot and gas-phase kinetics. Soot is a good radiator. In a sooting flame a substantial amount of energy will be transferred to the surroundings by thermal radiation. This transfer of energy will alter the temperature field of the flame and the change in temperature will affect the kinetics of soot and gas-phase chemistry. To simulate sooting flames correctly, it was therefore necessary to include a radiation model. To validate the coupled models of turbulence, combustion, soot, and radiation two different turbulent flames were simulated. One turbulent jet flame of methane and one turbulent jet flame of ethylene. For both flames the computed results were compared with measured values. Several aspects of the simulations are studied and discussed, such as the effect of the two-way coupling of soot and gas-phase kinetics on both soot yield and gas-phase composition, and the importance of a suitable radiation model. The two-way coupling of soot and gas phase kinetics is shown to have a positive effect on the computed soot volume fractions, and the results are considered to be encouraging. The work has demonstrated that the EDC has the capacity to handle different types of chemical reaction mechanisms, such as mechanisms for gas-phase combustion and soot kinetics, without modification.

No description available.

Detta arbete handlar om hur man som grafiker kan optimera utnyttjandet av tillgängliga resurser och trots begränsningar i form av polygon- och texturbudgetar öka sina möjligheter att skapa estetiskt tilltalande grafik. Arbetet undersöker en rad olika tekniker som kan användas för att resursoptimera material samt testar och utvärderar dessa med hjälp av material från spelprojektet Break a Leg (BAL). Resultaten visar att det grafiska materialet i BAL tjänat otroligt mycket på att resursoptimeras och att optimeringen förbättrat den tekniska kvaliteten avsevärt genom ökat texelvärde och effektiviserad vertexdensitet och gett en positiv visuell inverkan. Genom att integrera resursoptimering i det naturliga arbetsflödet ökar man som grafiker sina möjligheter att skapa estetiskt tilltalande grafik utan att överskrida de förutbestämda tekniska gränserna.

A wastewater treatment plant has the task to refine the wastewater from substances that should not be released into the environment. The decomposition process can, in a simple way, be described as follows: micro-organisms breathe oxygen and eat unwanted substances. The environment in which the micro-organism lives is known as sludge and the correct amount of oxygen available in the sludge is important for the decomposition to be effective. The oxygenation of the sludge alone stands for about 30% of the plant’s energy consumption. The purpose of this thesis is to propose a controller for a new technology which oxygenates the sludge. In this project the oxygenation process is modeled. The model is then used to validate the proposed controllers by simulations. The result from this thesis is a PI controller with anti-windup. Other results are a monitoring system that can be used to detect toxic substances in the plant and an approach to, through the control of the oxygen level, minimize the plant’s power consumption.

Scania är en välkänd tillverkare av tunga lastfordon och bussar. De profilerar sig som det presigefyllda valet med hög teknologinivå. För att kunna leda utvecklingen av nya funktioner och motorer måste många tester av alla system i dessa fordon göras. Till detta används provceller speciellt ordnade för specifika lastbilskomponenter och många av dessa komponenter behöver en yttre kylning under drift varför flera av provcellerna har reglerade kylsystem. Vid uppgradering av kylsystem eller nybyggnation av provceller med kylsystem finns en önskan att kunna simulera och göra tester av kylsystemet innan det faktiska kylsystemet finns på plats, för att säkerställa prestandan innan någon investering görs. Detta examensarbete går ut på att genom att skapa vissa basmodeller för komponenter i kylsystem, möjliggöra simulering av godtyckliga kylsystem för utvärdering av olika reglerstrategier, designer och deras prestanda. Vid framtagning av modellerna användes mestadels fysikalisk modellering men även rent praktiska modeller för att fylla en funktion existerar. Det resulterande modellbiblioteket klarar av att visa dynamiska effekter mycket bra men dess statiska träffsäkerhet är inte lika exakt. Dynamiken är dock det viktiga och svårt att få fram på andra sätt, varför modellbiblioteket kan vara användbart vid bedömningar om reglerstrategier och prestanda. / Scania is a wellknown manufacturer of heavy transport vehicles such as trucks and buses. Their profile is to be the prestigeous choice with a high level of technology. To maintain the leading position in development of new functionality and engines, substantial testing is nessecary. This is accomplished by using testbeds specialized for different components and purposes. Many of these components need external cooling during operation which is why a cooling system is present in a large number of testbeds. When new testbeds are to be constructed or an old cooling system is to be redesigned, there is a desire to be able to simulate and run tests of the cooling system before the actual cooling system is in place, to make sure performance is at a high enough level, before any investment is made. The task in this master thesis is to construct, in a matlab and simulink environment, a set of base models for cooling system components. With this set, arbitrary cooling systems can be constructed and simulated to evaluate different designes, control strategies and performance. Physical modelling was the most common method when constucting the base models though some models have a pure practical function. The resulting model library is able to, when put together to a complete cooling system, show dynamic behaviour correctly but static accuracy is a bit off. When judging a new control strategy, dynamic behaviour is the most important aspect, and also the most difficult to get elsewhere, which is why the model library can still be very useful.