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  • Public defence: 2017-03-03 10:00 F3, Stockholm
    Zmijewski, Nicholas
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Hydraulic Engineering.
    Effects of Watershed Dynamics on Water Reservoir Operation Planning: Considering the Dynamic Effects of Streamflow in Hydropower Operation2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Water reservoirs are used to regulate river discharge for a variety of reasons, such as flood mitigation, water availability for irrigation, municipal consumption and power production purposes. Recent efforts to increase the amount of renewable power production have seen an increase in intermittent climate-variable power production due to wind and solar power production. The additional variable energy production has increased the need for regulating the capacity of the electrical system, to which hydropower production is a significant contributor. The hydraulic impact on the time lags of flows between production stations have often largely been ignored in optimization planning models in favor of computational efficiency and simplicity. In this thesis, the hydrodynamics in the stream network connecting managed reservoirs were described using the kinematic-diffusive wave (KD) equation, which was implemented in optimization schemes to illustrate the effects of wave diffusion in flow stretches on the resulting production schedule. The effect of wave diffusion within a watershed on the variance of the discharge hydrograph within a river network was also analyzed using a spectral approach, illustrating that wave diffusion increases the variance of the hydrograph while the regulation of reservoirs generally increases the variance of the hydrograph over primarily short periods. Although stream hydrodynamics can increase the potential regulation capacity, the total capacity for power regulation in the Swedish reservoir system also depends significantly on the variability in climatic variables. Alternative formulations of the environmental objectives, which are often imposed as hard constraints on discharge, were further examined. The trade-off between the objectives of hydropower production and improvement of water quality in downstream areas was examined to potentially improve the ecological and aquatic environments and the regulation capacity of the network of reservoirs.

  • Public defence: 2017-03-07 12:00 Pérez del Pulgar, stockholm
    Carvajal Carreño, William
    KTH, School of Electrical Engineering (EES), Electric Power and Energy Systems. Railways Research Group. IIT. UPComillas.
    Efficient driving of CBTC ATO operated trains2017Doctoral thesis, monograph (Other academic)
    Abstract [en]

    Energy consumption reduction is one of the priorities of metro operators, due to financial cost and environmental impact. The new signalling system Communications-Based Train Control (CBTC) is being installed in new and upgraded metro lines to increase transportation capacity. But its continuous communication feature also permits to improve the energy performance of traffic operation, by updating the control command of the Automatic Train Operation (ATO) system at any point of the route. The present research addresses two main topics. The first is the design of efficient CBTC speed profiles for undisturbed train trajectory between two stations. The second takes into account the interaction between two consecutive trains under abnormal traffic conditions and proposes a tracking algorithm to save energy.

    In the first part of the research an off-line methodology to design optimal speed profiles for CBTC-ATO controlled trains is proposed. The methodology is based on a new multi-objective optimisation algorithm named NSGA-II-F, which is used to design speed profiles in such a way that can cover all the possible efficient solutions in a pseudo-Pareto front. The pseudo–Pareto front is built by using dominated solutions to make available a complete set of feasible situations in a driving scenario. The uncertainty in the passenger load is modelled as a fuzzy parameter. Each of the resulting speed profiles is obtained as a set of parameters that can be sent to the ATO equipment to perform the driving during the operation.

    The proposed optimisation algorithm makes use of detailed simulation of the train motion. Therefore, a simulator of the train motion has been developed, including detailed model of the specific ATO equipment, the ATP constraints, the traction equipment, the train dynamics and the track.

    A subsequent analysis considers the effect in the design of considering the regenerative energy flow between the train and the surrounding railway system.

    The second part of the research is focused on the proposal and validation of a fuzzy tracking algorithm for controlling the motion of two consecutive trains during disturbed conditions. A disturbed condition is understood as a change in the nominal driving command of a leading train and its consequences in the subsequent trains. When a train runs close enough to the preceding one, a tracking algorithm is triggered to control the distance between both trains. The following train receives the LMA (limit of movement authority) via radio, which is updated periodically as the preceding train runs. The aim of the proposed algorithm is to take actions in such a way that the following train could track the leading train meeting the safety requirements and applying an energy saving driving technique (coasting command). The uncertainty in the variations of the speed of the preceding train is modelled as a fuzzy quantity. The proposed algorithm is based on the application of coasting commands when possible, substituting traction/braking cycles by traction/coasting cycles, and hence saving energy. Both algorithms were tested and validated by using a detailed simulation program. The NSGA-II-F algorithm provided additional energy savings when compared to fixed block distance-to-go configurations, and giving a more even distribution of the solutions. The fuzzy tracking algorithm provides energy savings with a minor impact on running times while improving comfort, because of the reduction of the inefficient traction/braking cycles.

    The full text will be freely available from 2017-03-01 00:00
  • Public defence: 2017-03-08 10:00 Kollegiesalen, Stockholm
    Bjurström, Henrik
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Non-contact surface wave measurements on pavements2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In this thesis, nondestructive surface wave measurements are presented for characterization of dynamic modulus and layer thickness on different pavements and cement concrete slabs. Air-coupled microphones enable rapid data acquisition without physical contact with the pavement surface.

    Quality control of asphalt concrete pavements is crucial to verify the specified properties and to prevent premature failure. Testing today is primarily based on destructive testing and the evaluation of core samples to verify the degree of compaction through determination of density and air void content. However, mechanical properties are generally not evaluated since conventional testing is time-consuming, expensive, and complicated to perform. Recent developments demonstrate the ability to accurately determine the complex modulus as a function of loading time (frequency) and temperature using seismic laboratory testing. Therefore, there is an increasing interest for faster, continuous field data evaluation methods that can be linked to the results obtained in the laboratory, for future quality control of pavements based on mechanical properties.

    Surface wave data acquisition using accelerometers has successfully been used to determine dynamic modulus and thickness of the top asphalt concrete layer in the field. However, accelerometers require a new setup for each individual measurement and are therefore slow when testing is performed in multiple positions. Non-contact sensors, such as air-coupled microphones, are in this thesis established to enable faster surface wave testing performed on-the-fly.

    For this project, a new data acquisition system is designed and built to enable rapid surface wave measurements while rolling a data acquisition trolley. A series of 48 air-coupled micro-electro-mechanical sensor (MEMS) microphones are mounted on a straight array to realize instant collection of multichannel data records from a single impact. The data acquisition and evaluation is shown to provide robust, high resolution results comparable to conventional accelerometer measurements. The importance of a perfect alignment between the tested structure’s surface and the microphone array is investigated by numerical analyses.

    Evaluated multichannel measurements collected in the field are compared to resonance testing on core specimens extracted from the same positions, indicating small differences. Rolling surface wave measurements obtained in the field at different temperatures also demonstrate the strong temperature dependency of asphalt concrete.

    A new innovative method is also presented to determine the thickness of plate like structures. The Impact Echo (IE) method, commonly applied to determine thickness of cement concrete slabs using an accelerometer, is not ideal when air-coupled microphones are employed due to low signal-to-noise ratio. Instead, it is established how non-contact receivers are able to identify the frequency of propagating waves with counter-directed phase velocity and group velocity, directly linked to the IE thickness resonance frequency.

    The presented non-contact surface wave testing indicates good potential for future rolling quality control of asphalt concrete pavements.

     

  • Public defence: 2017-03-10 10:00 Ka-Sal C (Sal Sven-Olof Öhrvik), Kista, Stockholm
    Kargarrazi, Saleh
    KTH, School of Information and Communication Technology (ICT), Elektronics, Integrated devices and circuits.
    High Temperature Bipolar SiC Power Integrated Circuits2017Doctoral thesis, monograph (Other academic)
    Abstract [en]

    In the recent decade, integrated electronics in wide bandgap semiconductor technologies such as Gallium Nitride (GaN) and Silicon Carbide (SiC) have been shown to be viable candidates in extreme environments (e.g high-temperature and high radiation). Such electronics have applications in down-hole drilling, automobile-, air- and space- industries. In this thesis, integrated circuits (ICs) in bipolar 4H-SiC for high-temperature power applications are explored. In particular, device modelling, circuit design, layout design, and measurements are discussed for a range of circuits including operational amplifiers, linear voltage regulators, drivers for power switches, and power converters with integrated control. The circuits were demonstrated and tested from 25 °C up to 500 °C. Circuit design in bipolar SiC technology involves challenges such as the fabrication process’ uncertainties and incomplete models of the devices. Furthermore, high temperature modelling of the integrated devices is needed for circuit design and simulation. From the circuit design viewpoint, techniques such as negative-feedback, temperature-insensitive biasing, buffering and Darlington stages, and amplifiers with fewer gain stages, were shown to be useful for high-temperature IC design in bipolar SiC. It is shown that the linear voltage regulator can be improved by using a tailored high-current lateral Darlington power device in the same fabrication process. This results in a high temperature high current power supply solution. Moreover, the drivers can be improved by design in order to provide higher voltage levels and peak currents for the power devices (bipolar and MOSFET based). In addition, a DC-DC converter with fully integrated hysteretic control is designed taking advantage of several sub-circuits such as operational amplifier, Schmitt trigger and driver for the power switch. This study is followed by preliminary experimental results for the converter and controller IC.

  • Public defence: 2017-03-10 13:00 Kollegiesalen, Stockholm
    Ehrnberger, Karin
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Product and Service Design.
    TILLBLIVELSER: En trasslig berättelse om design som normkritisk praktik2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The increasing awareness of norm-critical perspectives (in society, academia and industry) brings with it the need to develop methods to ensure they can be implemented in practice. This thesis discusses how the role of design contributes to and maintains norms, and shows how design as a norm critical practice has great potential to bridge the gap between theory and practice in norm-critical work. This potential lies in using design as a peda-gogic tool that can concretize and make understandable what would otherwise be perceived as complex, unclear or remote. The thesis pays special attention to the role of artefacts in the creation of the stories of the world. The discursive design thing is introduced as a tool to visualize norms and to create discussion. The three-dimensional, physical thing exposes us to a more diverse experience of norms than when we just address them in words or pictures.The empirical work in this thesis stems from five research projects that differ from each other and were carried out under varied conditions. The projects have tackled a range of problems and power relationships. However, together they draw a complex picture of how norms arise, overlap and constantly change over time, place and space – and how design can be used to support or disrupt this process.By revisiting the projects, it becomes clear how the researcher’s position and actions (or non-actions) shape the norm development process. This results in an insight that meaning can not be construc-ted from an outside perspective, but is a constant ”becoming” that occurs in an entanglement of relationships arising between different bodies, both human and non-human. As a norm critical perspective implies paying attention to power relationships, it also assumes a power critical approach to the production of meaning extracted from the norm-critical work, and that we – as researchers and designers – take responsibility for our prevail by highlighting our own bodies and gaze.The thesis therefore proposes the concept of diffraction as an approach to the production of meaning in norm critical design practices. A diffractive approach enables an understanding of how the production of meaning occurs in various coincidences, but also how our own interventions shape the story. It opens up to the realization that parallel narratives are possible and thus becomes a tool to break away from the linear understanding framework and offer an exploration of alternative thought patterns. A diffractive approach to the production of meaning is thus also a tool to pro-mote increased creativity.

  • Public defence: 2017-03-17 09:30 D2, Stockholm
    Brown, Nils W. O.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Environmental Strategies (moved 20130630).
    Managing high environmental performance?: Applying life cycle approaches and environmental certification tools in the building and real estate sectors2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The main aim of this thesis is  to demonstrate and critically assess life cycle approaches’ and environmental certification (EC) tools’ potential for supporting decisions for improved environmental performance in the building and real estate sectors.

    Using life cycle approaches, the thesis shows that for new build and renovation cases aiming for low operational energy use that embodied global warming potential (GWP) due to material production can constitute a large portion of a building’s lifetime GWP. Therefore life cycle based information about materials’ embodied GWP needs to be made available to and utilized by design process decision makers.

    It was also shown that applying the Swedish EC tool Miljöbyggnad was useful in highlighting potential positive and negative changes in indoor environmental quality arising from renovation packages aiming at significant operational energy use reduction in existing multifamily buildings. However such renovation packages are not profitable from a property owner perspective. Miljöbyggnad may be useful when designing policy instruments to overcome this.   

    The thesis also showed that EC and related environmental enhancements contribute to achieving property owners’ and tenants’ overall strategic objectives for value creation. For property owners this arises for example through lower energy costs and attracting desirable tenants. For tenants, value creation arises as support for internal and external environmental communication.

    For the further development of life cycle approaches’ and EC tools’ application to buildings and real estate it is important to consider how they can be adapted to consider ‘distance to sustainable’ targets referencing for instance the planetary boundaries approach. It is also interesting to investigate how valuation of buildings and real estate may be performed in a way that expands from the current narrow focus on the economic perspective to also include environmental and social perspectives.

  • Public defence: 2017-03-17 10:00 Kollegiesalen, Stockholm
    Raj, Akanksha
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Synergies in Biolubrication2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The objective of this thesis was to advance understanding in the field of biolubrication, finding inspiration from the human synovial joints. This was addressed by investigating the association of key biolubricants and the resulting lubrication performance. Techniques employed during the course of this work were Atomic force microscopy (AFM), Quartz crystal microbalance with dissipation monitoring (QCM-D), X-ray reflectivity (XRR).

    Key synovial fluid and cartilage components like dipalmitoylphosphatidylcholine (DPPC), hyaluronan (HA), lubricin, and cartilage oligomeric matrix protein (COMP) have been used in the investigations. Focus was towards two lubrication couples; DPPC-hyaluronan and COMP-lubricin. DPPC-hyaluronan mixtures were probed on hydrophilic silica surfaces and COMP-lubricin association structures were explored on weakly hydrophobic poly (methyl methacrylate) (PMMA) surfaces.

    Investigations of the COMP-lubricin pair revealed that individually these components are unable to reach desired lubrication. However in combination, COMP facilitates firm attachment of lubricin to the PMMA surface in a favourable confirmation that imparts low friction coefficient.

    DPPC and hyaluronan combined impart lubrication advantage over lone DPPC bilayers. Hyaluronan provides a reservoir of DPPC on the surface and consequently self-healing ability.

    Other factors like temperature, presence of calcium ions, molecular weight of hyaluronan, and pressure were also explored. DPPC bilayers at higher temperature had higher load bearing capacity. Association between DPPC Langmuir layers and hyaluronan was enhanced in the presence of calcium ions, and lower molecular weight hyaluronan had a stronger tendency to bind to DPPC. At high pressures, DPPC-hyaluronan layers were more stable compared to lone DPPC bilayers.

  • Public defence: 2017-03-17 10:00 Q2, Stockholm
    Huang, Yalin
    KTH, School of Electrical Engineering (EES), Electric Power and Energy Systems.
    Economic Regulation Impact on Electricity Distribution Network Investment Considering Distributed Generation2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    One of EU’s actions against climate change is to meet 20% of energy consumption from renewable resources by the year 2020 when the project was started. Now this target has increased to at least 27% by the year 2030. In addition, given that the renewable resources are becoming more economical to generate electricity from and that these resources are distributed geographically, more and more distributed generation (DG) is connected to power distribution. The increasing share of DG in the electricity networks implies re-distribution of costs and benefits among distribution system operators (DSOs), customers and DG owners. How the costs and benefits will be allocated among them depends on the established economic regulation.

    The established economic regulation regulates the DSOs’ revenue and performances. The time when the DSOs are remunerated based on their actual costs has passed. Nowadays the economic regulation is in place to steer efficient investments. Network investments are no longer just to satisfy the load growth, or to higher the investments does not bring higher revenue. Network investments are incentivised by the regulation to be more efficient. Furthermore, the potential of DG to defer network investment is widely recognized. Ignoring this potential of DG may decrease DSOs’ efficiency. Last but not the least; network unbundling is a common practice in Europe. Ignoring the fact that DSOs and DG owners are different decision makers in studies can lead to inaccurate analysis.

    Driven by the target of a higher DG integration and more efficient investments in the unbundled distribution networks, proper economic regulations are needed to facilitate this change. The objective of this thesis is to evaluate the impact from regulations on distribution network investment considering DG integration. In other words, this thesis aims to develop methods assist regulators to design desirable regulations to encourage the DSOs to make the “smart” decisions. In order to achieve that, we propose a modelling approach to quantify the economic regulation impacts and the benefit of innovative investments. Regulations are encoded into the network investment model. The developed models, in other words, assist DSOs to make the “right” investment in the “right” place at the “right” time under the given regulation.

  • Public defence: 2017-03-17 10:00 D3, Stockholm
    Gil Gómez, Gaspar
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Vehicle Dynamics. Volvo Cars.
    Towards efficient vehicle dynamics development: From subjective assessments to objective metrics, from physical to virtual testing2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Vehicle dynamics development is strongly based on subjective assessments (SA) of vehicle prototypes, which is expensive and time consuming. Consequently, in the age of computer- aided engineering (CAE), there is a drive towards reducing this dependency on physical test- ing. However, computers are known for their remarkable processing capacity, not for their feelings. Therefore, before SA can be computed, it is required to properly understand the cor- relation between SA and objective metrics (OM), which can be calculated by simulations, and to understand how this knowledge can enable a more efficient and effective development process.

    The approach to this research was firstly to identify key OM and SA in vehicle dynamics, based on the multicollinearity of OM and of SA, and on interviews with expert drivers. Sec- ondly, linear regressions and artificial neural network (ANN) were used to identify the ranges of preferred OM that lead to good SA-ratings. This result is the base for objective require- ments, a must in effective vehicle dynamics development and verification.

    The main result of this doctoral thesis is the development of a method capable of predicting SA from combinations of key OM. Firstly, this method generates a classification map of ve- hicles solely based on their OM, which allows for a qualitative prediction of the steering feel of a new vehicle based on its position, and that of its neighbours, in the map. This prediction is enhanced with descriptive word-clouds, which summarizes in a few words the comments of expert test drivers to each vehicle in the map. Then, a second superimposed ANN displays the evolution of SA-ratings in the map, and therefore, allows one to forecast the SA-rating for the new vehicle. Moreover, this method has been used to analyse the effect of the tolerances of OM requirements, as well as to verify the previously identified preferred range of OM.

    This thesis focused on OM-SA correlations in summer conditions, but it also aimed to in- crease the effectiveness of vehicle dynamics development in general. For winter conditions, where objective testing is not yet mature, this research initiates the definition and identifica- tion of robust objective manoeuvres and OM. Experimental data were used together with CAE optimisations and ANOVA-analysis to optimise the manoeuvres, which were verified in a second experiment. To improve the quality and efficiency of SA, Volvo’s Moving Base Driving Simulator (MBDS) was validated for vehicle dynamics SA-ratings. Furthermore, a tablet-app to aid vehicle dynamics SA was developed and validated.

    Combined this research encompasses a comprehensive method for a more effective and ob- jective development process for vehicle dynamics. This has been done by increasing the un- derstanding of OM, SA and their relations, which enables more effective SA (key SA, MBDS, SA-app), facilitates objective requirements and therefore CAE development, identi- fies key OM and their preferred ranges, and which allow to predict SA solely based on OM. 

  • Public defence: 2017-03-17 13:00 B2, Stockholm
    Medineckiene, Milena
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology.
    Integrated decision making in civil engineering, based on multi-criteria assessment and buildings’ certification2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Significant investments are being made in the construction sector in order to raise the quality of the buildings and make them more sustainable and energy-efficient. The key aspect of these investments should be the purposeful optimization of the possible renovation and construction measures. However, this important matter usually is being pushed aside in favor of construction price and/or quality. Nevertheless, there are plenty of criteria that play a major role in building sustainable development.

    The main purpose of this study is to present a tool that combines multi-criteria decision making (MCDM) methods and building certification systems in order to make weighted decisions in complicated construction tasks. For this, a decision making model was developed with a focus on sustainability, buildings’ life cycle, MCDM methods, and building certification.

    The first section of this thesis, the introduction, discusses the importance of the investigated area, and the main objectives, tasks, and structure of the thesis.

    A literature review is presented in Section 2 – Theory. The main works in the area of sustainability, LCA, building certification, and MCDM are collected to show their role and importance and how they interact in the construction industry.

    Section 3 presents and discusses the main ideas and instructions of the proposed decision making model.

    Section 4 (Methodology) introduces the main existing and proposed techniques that I have used to implement the study.

    Sections 5 and 6 are the case studies, which demonstrate how the proposed methods can be used in practice.

    Final conclusions and recommendations are presented in Section 7.

  • Public defence: 2017-03-22 10:00 F3, Stockholm
    Fang, Yuan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Ions interacting with macromolecules: NMR studies in solution2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Specific ion effects, identified for more than hundred years, play an important role in a wide range of phenomena and applications. Several mechanisms such as direct ion interaction with molecules have been suggested to explain these effects, but quantitative experimental evidence remains scarce. Electrophoretic NMR (eNMR) has been emerging as a very powerful tool for studying molecular association and ionic transport in a variety of systems. Yet its potential in studying specific ion effect has been unexplored. In this thesis, eNMR was in part developed further as an analytical method and was in part used as one of the main techniques to study ions interacting with macromolecules in aqueous and non-aqueous solutions.

    The complexation of a large group of cations with poly ethylene oxide (PEO) in methanol was studied with eNMR. The binding of monovalent ions was demonstrated not to follow the Hofmeister order; multivalent cations except barium all showed negligible complexation. As a unifying feature, only cations with surface charge density below a threshold value were able to bind suggesting that ion solvation is critical. The binding mechanism was examined in greater detail for K+ and Ba2+ with oligomeric PEO of different chain lengths. Those two cations exhibited different binding mechanisms. K+ was found to bind to PEO by having at least 6 repeating units wrap around it while retaining the polymer flexibility. On the other hand, Ba2+ (and, to some extent, (BaAnion)+) needs a slightly shorter section to bind, but the molecular dynamics at the binding site slow considerably.

    The binding of anions with poly (N-isopropylacrylamide) in water was quantified at low salt concentration with eNMR and the binding affinity, though very weak, followed the Hofmeister order. This result indicates the non-electrostatic nature of this specific ion effects. The increase of binding strength with salt concentration is well described by a Langmuir isotherm.

    The specific ion binding to a protein, bovine serum albumin (BSA), was also studied at pH values where BSA has either net positive and negative charges. Our results show that anions have the same binding affinity irrespective of the surface charge while the binding strength of cations is reversed with the change in net surface charge. This indicates different binding mechanisms for cations and anions.

    The ionization of cellobiose in alkaline solutions was measured quantitatively by eNMR. The results show a two-step deprotonation process with increasing alkaline strength. Supported by results from 1H-13C HSQC NMR and MD simulation, ionization was proposed to be responsible for the improved solubility of cellulose in alkaline solution. eNMR was also used to characterize the effective charge of tetramethylammonium ions in a variety of solvents. In solvents of high polarity, the results agree well with predictions based on Onsager’s limiting law but for nonpolar solvents deviations were found that were attributed to ion pair formation. 

  • Public defence: 2017-03-24 10:00 FB53, Stockholm
    Riad, Stella
    KTH, School of Engineering Sciences (SCI), Physics, Theoretical Particle Physics.
    Phenomenology of neutrino properties, unification, and Higgs couplings beyond the Standard Model2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The vast majority of experiments in particle physics can be described by the Standard Model of particle physics (SM). However, there are indications for physics beyond it. The only experimentally demonstrated problem of the model is the difficulty to describe neutrino masses and leptonic mixing. There is a plethora of models that try to describe these phenomena and this thesis investigates several possibilities for new models, both full theories and effective frameworks.

     

    The values of the parameters in a model are dependent on the energy scale and we say that the parameters run. The exact behavior of the running depends on the model and it provides a signature of the model. For a model defined at high energies it is necessary to run the parameters down to the electroweak scale in order to perform a comparison to the known values of observed quantities. In this thesis, we discuss renormalization group running in the context of extra dimensions and we provide an upper limit on the cutoff scale. We perform renormalization group running in two versions of a non-supersymmetric SO(10) model and we show that the SM parameters can be accommodated in both versions. In addition, we perform the running for the gauge couplings in a large set of radiative neutrino mass models and conclude that unification is possible in some of them.

     

    The Higgs boson provides new possibilities to study physics beyond the SM. Its properties have to be tested with extremely high precision before it could be established whether the particle is truly the SM Higgs boson or not. In this thesis, we perform Bayesian parameter inference and model comparison. For models where the magnitude of the Higgs couplings is varied, we show that the SM is favored in comparison to all other models. Furthermore, we discuss lepton flavor violating processes in the context of the Zee model. We find that these can be sizeable and close to the experimental limits.

  • Public defence: 2017-03-24 10:00 M311, Stockholm
    Alhusin Alkhdur, Abdullah
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Toward a Sustainable Human-Robot Collaborative Production Environment2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This PhD study aimed to address the sustainability issues of the robotic systems from the environmental and social aspects. During the research, three approaches were developed: the first one an online programming-free model-driven system that utilises web-based distributed human-robot collaboration architecture to perform distant assembly operations. It uses a robot-mounted camera to capture the silhouettes of the components from different angles. Then the system analyses those silhouettes and constructs the corresponding 3D models.Using the 3D models together with the model of a robotic assembly cell, the system guides a distant human operator to assemble the real components in the actual robotic cell. To satisfy the safety aspect of the human-robot collaboration, a second approach has been developed for effective online collision avoidance in an augmented environment, where virtual three-dimensional (3D) models of robots and real images of human operators from depth cameras are used for monitoring and collision detection. A prototype system is developed and linked to industrial robot controllers for adaptive robot control, without the need of programming by the operators. The result of collision detection reveals four safety strategies: the system can alert an operator, stop a robot, move away the robot, or modify the robot’s trajectory away from an approaching operator. These strategies can be activated based on the operator’s location with respect to the robot. The case study of the research further discusses the possibility of implementing the developed method in realistic applications, for example, collaboration between robots and humans in an assembly line.To tackle the energy aspect of the sustainability for the human-robot production environment, a third approach has been developed which aims to minimise the robot energy consumption during assembly. Given a trajectory and based on the inverse kinematics and dynamics of a robot, a set of attainable configurations for the robot can be determined, perused by calculating the suitable forces and torques on the joints and links of the robot. The energy consumption is then calculated for each configuration and based on the assigned trajectory. The ones with the lowest energy consumption are selected.

  • Public defence: 2017-04-07 09:00 Sal F3, Stockholm
    Khurshid, Mansoor
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Static and fatigue analyses of welded steel structures: some aspects towards lightweight design2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The objectives of this thesis comprise of overcoming the challenges in designing lightweight welded structures such as material selection, choice of fatigue design methods, and increased performance by using improvement techniques. Material selection of welded joints is dependent on the filler and base material strengths. Partially and fully penetrated cruciform and butt welded joints were designed in under-matching, matching, and over-matching filler materials. Base material steel grades were S600MC, S700MC, and S960. Current design rules are developed for welds in steel up to yield strength of 700MPa. Therefore, design rules in Eurocode3, AWS d1.1, and BSK 07 were verified and recommendations for developing design rules for designing welded joints in S960 were concluded. Numerical methodology for estimating static strength of welded joints by simulating heat affected zone was also developed.

    Another objective of the thesis work was to overcome the challenges in selection of fatigue design methods. The available design curves in standards are developed for uniaxial stress states, however, in real life the welds in mechanical structures are subjected to complex multiaxial stress states. Furthermore; weld toe failures are frequently investigated, weld root failures are seldom investigated. Therefore, in this work the multiaxial fatigue strength of welded joints failing at the weld root was assessed using experiments and various nominal and local stress based approaches. Butt welded joints with different weld seam inclinations with respect to applied uniaxial loading were designed to assess the root fatigue strength in higher multiaxial stress ratio regime. The fatigue strength of multi-pass tube-to-plate welded joints subjected to internal pressure only and combined internal pressure and torsion in and 90° out of phase loading was also investigated. Test data generated in this thesis was evaluated together with the test data collected from literature.

    Last objective of the thesis included investigation of the increased performance in fatigue strength by post weld treatment methods such as HFMI. The behavior of residual stresses induced due to HFMI treatment during fatigue loading is studied. Numerical residual stress estimations and residual stress relaxation models are developed and the effect of various HFMI treatment process parameters and steel grade on the induced residual stress state is investigated. Specimens studied were non load carrying longitudinal attachments and simple plates. Residual stresses in both test specimens were measured using X-ray diffraction technique.