This master thesis is a part of a larger development project initiated at the department of Naval Architecture at KTH. The project goal is to design and manufacture a full scale proof-of-concept prototype of a electric powered two-wheeled amphibious vehicle. The focus of this thesis is the vehicle's front suspension system. In the present state, only a rough conceptual idea exist of the overall vehicle and its front suspension. The aim of this thesis is to analyze, evaluate and choose a suitable front suspension system and implement it into a detailed conceptual design. The rest of the vehicle is yet to be developed why the design boundaries for the front suspension are open-ended. This means that the design is likely to be revised in continued development. To deal with the open-ended boundaries a parameterized design is requested. An additional segment of the thesis is to produce parameterized development models used to derive the design. These models are considered as deliverables since they will be used when revising the front suspension for it to conform with the rest of the vehicle. With the information provided by the existing rough concept in terms of major components and vehicle architecture an estimation of the centre of gravity location have been carried out. This location enables a number of parameterized analytical models to be derived and utilized in the design of an optimized front suspension anti-dive geometry. The analytical models have been validated by creating a parametric ADAMS View model of the vehicle with a main purpose of simulating vehicle dynamics. The resulting design is a symmetric front swing arm suspension with a hub centre steering, torque arms and guide struts. An electric hub motor is also implemented in the wheel to provide tractive power in the front. The subsystem detailed conceptual design have been created in Solid Edge ST5 CAD software. Simplified finite element structural analysis in Ansys Workbench 14.0 is used to provide an initial estimate of the factor of safety for the parts. Because of the influence of the rest of the vehicle the proposed design delivered by this thesis is to be reviewed as a conceptual blueprint for the final front suspension. As there is no pre-existing design constraints from the rest of the vehicle the different subsystems are required to be parallel and iteratively developed due to their cross dependence. / Examensarbetet som följer i denna rapport är en del i ett större utvecklingsprojekt som startades på KTH Marina System. Målet med projektet är att utveckla och tillverka en fullskalig prototyp av ett tvåhjuligt elektriskt framdrivet amfibiefordon. Examensarbetets fokus ligger på utvecklingen av fordonets framhjulsupphängning. I nuläget existerar endast en grov konceptuell idé över hela fordonet och dess framhjulupphängning. Målet med examensarbetet är att analysera, utvärdera och välja en passande lösning för främre hjulupphängningen och implementera i en detaljerad konceptuell konstruktion. Eftersom resten av fordonet ännu inte har utvecklats existerar inga direkta angränsande system för konstruktionen. Den föreslagna konstruktionen kommer därför med hög sannolikhet behöva revideras när utvecklingen av fordonet går framåt. För att underlätta ändringar ska konstruktionen vara parametriserad. En annan del av examensarbetet är att ta fram utvecklingsmodeller, även dom parametriserade, som kommer att nyttjas i konstruktionsarbetet. Modellerna anses också som leverabler eftersom de även kommer att användas när konstruktionen behöver revideras för att passa samman med resten av fordonet. Den information som återfinns i den konceptuella iden över fordonet användes för att ta fram en uppskattning för positionen av fordonets masscentrum. Med hjälp av denna position har ett antal parametriserade analytiska modeller tagits fram och använts för att konstruera en hjulupphängningsgeometri. Geometrin har optimerats för så kallade anti-dive egenskaper, egenskaper som förhindrar att fordonets nos dyker vid kraftiga inbromsningar. De analytiska modellerna har validerats genom att en parametriserad ADAMS View modell av fordonet har tagits fram. Den resulterande främre hjulupphängningen är en symmetrisk swingarm med navstyrning, momentarmar och styrlänkar. En elektrisk navmotor är implementerad i hjulet för att tillföra drivkraft till framvagnen. De olika delarna har skapats i Solid Edge ST5 CAD programvara och förenklade hållfasthetsanalyser har genomförts i Ansys Workbench 14.0. På grund av beroendet mot det resterande fordonet som konstruktionen lider av måste den anses som en konceptuell sammanställningsritning av den slutgiltiga framhjulupphängningen. Utan några förutbestämda konstruktionsavgränsningar från övriga system behöver komponenternautvecklas parallellt och iterativt.

Ett essentiellt delsystem i motordrivna fordon är ett välfungerande bromssystem som ska möjliggöra fartminskning och inbromsning till en naturlig och bekväm känsla hos föraren. Ett välkänt problem med bromssystem i dagens personbilar är s.k. anliggning av bromsbelägg mot skiva. Detta problem uppkommer oftast efter en längre användning av bilen och innebär att inbromsning sker trots att föraren inte trycker på bromspedalen. För att lösa problemet måste bromssystemets ingående komponenter modifieras. Detta påverkar bromskänslan hos föraren. I detta kandidatarbete har en modell utvecklats med flera av bromssystemets komponenters egenskaper. Komponenter som huvudcylinder, bromsslang och bromsbelägg har studerats, och olika simuleringar har gjorts i Matlab (1) för att se hur deras elastiska egenskaper påverkat bromskänslan. Detta har gjorts på uppdrag av Brembo som tillverkar bromsok till högprestandabilar. Av denna anledning har bilen som valts att göra undersökningen på varit en Porsche Carrera 4S 911, då denna har bromsok från just Brembo. Vad gäller komponenternas funktionalitet så är exempelvis huvudcylinderns uppgift att omvandla kraften till ett vätsketryck som leds in till bromsslangarna. Dessa har således uppgiften att leda vätskan till bromsoken där bromsbeläggen pressas mot bromsskivan och fordonet bromsas in. Beroende på egenskaper och dimensioner på dessa komponenter kommer bromskänslan att förändras. Ingångsdata för egenskaperna kan avläsas enligt BILAGA A. Resultatet var att inbromsningstiden var 5,2 sekunder, pedalvägen var 4,5 cm och pedalkraften var 67 N med komponentegenskaper enligt BILAGA A. Dessa ändrades och en skillnad uppträdde i samtliga resultatdata. Slutsatsen är att bromsslangarnas elasticitet har en betydlig inverkan på bromskänslan om elasticitetmodulen är låg. Avståndet mellan belägg och skiva påverkar även bromskänslan på så sätt att pedalvägen blir längre och även huvudcylinderns dimensioner är betydande för bromskänslan. Denna slutsats baserar sig på resultatet som presenteras i denna rapport, trots att i princip samtliga komponentegenskaper påverkar bromskänslan mer eller mindre. Med hjälp av simuleringsmodellen i Matlabs GUI-program som bifogas kan undersökningen vidare fortsättas. / An essential subsystem on a motor driven vehicle is a well working braking system that facilitates braking and velocity reduction to a natural feeling for the driver. A well-known problem with braking systems in current automobiles is so called brake drag from the pads dragging on the rotor. This problem often occurs after a longer usage of the car and results in braking, even though the driver has not pushed the pedal. To solve this problem, the internal components of the brake system need to be modified. This affects the pedal feel of the driver. In this bachelor thesis, a simulation model has been developed containing several properties of the components in a braking system. Components such as master cylinder, brake hoses and brake pads have been studied and different simulations in Matlab have been done in order to see how their elasticity, and other properties, affected the brake feel. This has been done on a commission from Brembo, which produces brake calipers for high-performance cars. For this reason, the car chosen to be studied was a Porsche Carrera 4S 911 since this car originally has calipers manufactured by Brembo. As it comes to the functionality of the components, the master cylinder, for example, has the task to transform the incoming force to a fluid pressure along the brake hoses. Accordingly, these then have the task to transmit the fluid to the calipers where the pads are pushed against the rotor, which ultimately leads to braking and velocity reduction. Depending on the properties and the dimensions of these components the brake feel will change, more or less. The properties are assigned input data according to BILAGA A. The output result was that the vehicle stopping time was 5.2 seconds, the pedal travel was 4.5 cm and the pedal force was 67 N using the component properties according to BILAGA A. These were changed and a difference appeared on all output data. The conclusion is that the elasticity of the brake hoses made a significant influence if the elasticity modulus was set relatively low. The distance between brake disc and brake pad also affected the brake feel in such way that the pedal travel was longer. Moreover, the dimensions of the master cylinder had a significant influence on the brake feel. This result is based on the result presented in this report, however all the internal components affect the brake feel more or less. Using the attached Matlab GUI-program, the study can be continued further.

I den här rapporten presenteras ett konceptförslag till ett stativ tillhörande en av Danfoss Värmepumpar AB:s varmvattenberedare. Stativet är konstruerat för att hålla en varmvattenberedare vars vikt uppgår till 219 kg. Konceptet är en konstruktion med fyra ben i stål, vilka har en lutning mot mitten för att få god hållfasthet och stabilitet. Varmvattenberedaren fästs i en monteringsplåt som gör det möjligt att montera av och på denne vid behov. För att minska kostnaden görs alla grunddelar i stativet från samma plåtskiva, vilken har måtten 800x900mm. Stativets konstruktion medför en möjlighet att byta ut hela värmepumps-enheten vid behov. För att visualisera konceptet har en modell i SOLID EDGE gjorts, vilken sedan har importerats till ANSYS för FEM-analys. Vid hållfasthetsberäkningarna har transport och jordbävning beaktats för att säkerställa att konstruktionen håller. / This report presents a concept-proposal of a stand belonging to one of Danfoss Värmepumpar AB's water heaters. The stand is constructed to bear a water heater whose weight is 219 kg. The concept is a construction with four legs in steel, leaning towards the center of the stand to get good strength and stability. The water heater is attached to a mounting plate that makes it possible to dismantle if necessary. The stand's design also provides an opportunity to replace the entire water heater- unit. All the basic components of the stand are made from the same 800x900mm metal plate to reduce the costs and material consumption. To visualize the concept, a model has been made in SOLID EDGE, which was imported into ANSYS for calculations. Both earthquakes and transportation were taken into account in the calculations to ensure that the construction holds its purpose.

Renewable energy technologies are in the spotlight. On the one hand, they are called to have a leading role in the battle against climate change. On the other hand, with constantly growing installed capacity and more than generous Feed-in-Tariffs (FiT’s), they might represent the financial demise of the energy sector of some countries. This is the case for concentrated solar power (CSP) in Spain. It is one of the country’s trademark industries and it is also a financial sink, with Feed-in Tariffs that were more than six times higher than the regular market price, before an energy reform had to be introduced. This work is divided in three main parts. The first part consists of an assessment of the regulatory changes and their impact on the Spanish CSP industry, which by July 2013, amount to at least 17% in revenue losses for the industry without taking into account variable losses related to the use of backup fossil fuels. These changes have created an atmosphere of great uncertainty for the industry, since the profitability of their projects has been severely challenged. The second part of this report consists of an evaluation of the operational performance of two parabolic trough CSP plants during their commissioning period. Two different methods were used; the first method consists of an annual or semi-annual evaluation where the main intakes and outputs (gas, water and electricity consumption, as well as, power generation) are compared with fixed guaranteed values. The second method consists of a daily evaluation of the power generation curves of the plants. The first evaluation showed positive results, with both power plants operating within the guaranteed values. The second evaluation fulfilled its objective by highlighting opportunities for improvement for both plants. Problems were brought up by the evaluation and subsequently identified and solved by the operation and maintenance (O&M) crew, increasing the net output of the plants by more than 1.5 MW. Last but not least, some critical components were successfully identified by means of reviewing the corrective actions performed during the year, opening an opportunity to reduce downtime by having proper spare parts stocks, and addressing design issues with equipment suppliers. The results presented by this report are not specific to these two power plants. The regulatory changes and the reduction of the FiT’s present a difficult challenge for the whole Spanish renewable energy (RE) industry and a real threat to the future development of these technologies. In the case of CSP, there is still work to do, especially by equipment suppliers, since the most relevant issues found were related to a lack of reliability of the components. These financial and technological problems should be solved jointly by the government, the producers, and the equipment suppliers in order to bring the CSP industry closer to its financial and technological maturity.

One way of achieving more fuel efficient, more environmentally friendly and user-friendly Heavy-duty vehicles is to develop new embedded control features. Many of these features are based on vehicle mass is known. Methods of finding the current vehicle mass can be implemented in many different ways, including various methods that require user interaction or manual weighing of the vehicle. These should be avoided as they are inefficient and add operations to the driver. Another alternative method is estimation by adaptive filters. This examination is based on this method and assumes that the road grade is known. The method developed consists primarily of a recursive least squares method to estimate against a physical vehicle model in the longitudinal direction. The time-varying input signals are noise reduced by stepwise integration into intervals of 10 seconds and low-pass filtering. For estimation to be carried out, a number of conditions have been set. Verification of the method was carried out through both simulations and by executing it in a vehicle's control system. The results show that the mass is estimated with a relative error of 5 % after 600 seconds of driving. The conclusions include that this method gives a good estimation and it does not stress the vehicle control system so that it becomes unusable. Before using this method, more work should be performed on getting a more accurate model of vehicle, especially on the parameters used in this. / Ett sätt att nå mer bränsleeffektiva, mer miljövänliga och användarvänliga tunga fordon är att utveckla ny styrfunktionalitet. Många av dessa funktioner bygger på att fordonsmassan är känd hos fordonets styrsystem. Att ta reda på aktuell fordonsmassa kan genomföras på många olika sätt, bland annat olika metoder som kräver användarinteraktion eller manuell vägning av fordonet. Dessa bör dock undvikas då de är ineffektiva och tillför arbetsmoment för föraren. En annan alternativ metod för masskattning är estimering med hjälp av adaptiva filter. Detta examensarbete bygger på denna metod och förutsätter att väglutningen är känd. Metoden som utvecklas består främst av en rekursiv minstakvadratmetod som estimerar mot en fordonsmodell i longitudinell led. De tidsvarierande insignalerna brusreduceras genom stegvis integrering i intervall om 10 sekunder samt lågpassfiltrering. För att estimering ska kunna utföras har ett antal villkor har satts upp. Verifikation av metoden utfördes både genom simuleringar samt genom att exekvera den i ett fordons styrsystem. Resultaten visar att massan estimeras med ett relativt fel på 5 % efter 600 sekunders körning. Slutsatserna är bland annat att denna metod ger en bra estimering och att den inte belastar fordonets styrsystem så att det blir obrukbart. Innan metoden börjar användas bör mer arbete läggas på att få en mer korrekt fordonsmodell, framförallt på de parametrar som används i denna.

The present measurement campaign on the free-stream turbulence (FST) induced boundary layer transition scenario has provided a unique set of experimental data, with potential to enhance the understanding of the eect of the free-stream turbulence characteristic length scales on the transition location and not only the turbulence intensity, which has been the focus in most previous studies. Recent investigations where the turbulence intensity has been kept essentially constant, while the integral length scale has been changed, show that the transition location is advanced for increasing length scale. However, the present data show that the integral and Taylor length scales of the FST have a relatively small inuence on the transition location as compared to the turbulence intensity and data analyses are now directed towards enhanced understanding of how the dierent parts of the incoming energy spectrum aects the energy growth inside the boundary layer. / QC 20110526

<p>QC 20101110</p>

A vital part in the transmission for Scania lorries is the shaft in the rear axle. Since this shaft is divided into two identical parts, these are termed half shafts. Close control of the manufacturing process of these is required. Influence of flow rate, temperature and polymer concentration of the quenchant was investigated. An important controlling factor is the cooling rate used in the hardening process. This factor was selected for investigation in the present study. It was found that high flow rate, low temperature and low polymer concentration gives high cooling rates. Further investigation was performed how the residual stresses, surface hardness and the case depth of the half shafts were affected by the cooling rate. The results show that residual stresses are particularly affected by the cooling rate. Higher cooling rates results in higher residual stresses. Since residual stresses are important for fatigue lifer, a fatigue study was also undertaken. Five half shafts were quenched with a polymer concentration of 5%, and another five with 15%. All ten half shafts were fatigue tested in torsion, using a Scania standardized method. The shafts were loaded in torsion torque with company confidential amplitude, mean equal to zero number of cycles to failure was recorded. In normal production the half shafts are quenched with 10% polymer concentration. No tests with a polymer concentration of 10% were carried out in this investigation since results from this concentration are available from earlier studies. Residual stresses were measured using a relatively new method developed by Scania, called the core drilling method. A 20 cm long portion of the shaft was center drilled in steps, gradually increasing the drill diameter. After each step, the relaxation of surface strain was measured in the longitudinal and transversal directions. Having obtained these data, stresses can be calculated. Residual stresses were also measured by x-ray diffraction. Only surface stresses are obtained in this way, however. These measurements were made for each of the three polymer concentrations. An attempt was also made on trying to simulate the stress formation in the shafts during the heat treatment with FEM and also to calculate the residual stresses after the treatment. Results from the measurements were then compared with the FEM calculated results. Since the number of tested shafts is small, results are not statistically relevant. One may conclude, though, that fatigue life increases with increasing cooling rate, i.e. with decreasing polymer concentration. The fatigue life requirement for all tested shafts was fulfilled. The compressive residual stresses for 5% and 10% polymer concentration are of same magnitude and higher than for those quenched with 15% polymer concentration. The result also shows that the cooling rate does not affect the surface hardness, nor the case depth.

This thesis performs a research on scheduling algorithms for parallel appli-cations. The main focus is their usage on multi-core embedded systems’ appli-cations. A parallel application can be described by a directed acyclic graph. A directed acyclic graph is a mathematical model that represents the parallel application as a set of nodes or tasks and a set of edges or communication messages between nodes.In this thesis scheduling is limited to the management of multiple cores on a multi-core platform for the execution of application tasks. Tasks are mapped onto the cores and their start times are determined afterwards. A toolchain is implemented to develop and schedule parallel applications on a Epiphany E16 developing board, which is a low-cost board with a 16 core chip called Epiphany. The toolchain is limited to the usage of o˜ine scheduling algorithms which compute a schedule before running the application.The programmer has to draw a directed acyclic graph with the main at-tributes of the application. The toolchain then generates the code for the target which automatically handles the inter-task communication. Some metrics are established to help evaluate the performance of applications on the target plat-form, such as the execution time and the energy consumption. Measurements on the Epiphany E16 developing board are performed to estimate the energy consumption of the multi-core chip as a function of the number of idle cores.A set of 12 directed acyclic graphs are used to verify that the toolchain works correctly. They cover di˙erent aspects: join nodes, fork nodes, more than one entry node, more than one exit node, di˙erent tasks weights and di˙erent communication costs.A use case is given, the development of a brake-by-wire demonstration platform. The platform aims to use the Epiphany board. Three experiments are performed to analyze the performance of parallel computing for the use case. Three brake-by-wire applications are implemented, one for a single core system and two for a multi-core system. The parallel application scheduled with a list-based algorithm requires 266% more time and 1346% more energy than the serial application. The parallel application scheduled with a task duplication algorithm requires 46% less time and 134% more energy than the serial application.The toolchain system has proven to be a useful tool for developing paral-lel applications since it automatically handles the inter-task communication. However, future work can be done to automatize the decomposition of serial applications from the source code. The conclusion is that this communication system is suitable for coarse granularity, where the communication overhead does not a˙ect so much. Task duplication is better to use for fine granularity since inter-core communication is avoided by doing extra computations.

Model Predictive Control is a receding horizon control technique that is based on making predictionsin the future for a determined number of steps, using a model of the system to be controlled. Thisthesis report is centered around Model Predictive Control (MPC) and its application. In this thesis,there are two main goals: firstly, is the development of a software structure that uses the properties ofObject Oriented Programming (OOP) and the Robot Operative System (ROS) to ease the use of MPCapplications. Secondly, the use and verification of the capabilities of MPC controllers in plants with fastdynamics, such as the quadrotor. A linearized model of the quadrotor is developed for the controllerto perform the predictions, and the non-linear version is used to make a numerical simulator to test theapplication. The MPC software structure works as it successfully integrates information from the classesthat represent the model and optimization method to solve the quadratic problem. The resulting MPCcontroller shows a good response when following simple trajectories in the presence of simulated noise.However, when more complex trajectories are used, a considerable offset from the reference is obtained.Such behavior mostly caused by the use of a very limited model, which demonstrates the considerablesensibility of the controller to the accuracy of the used model.