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  • Krokos, Evangelos
    KTH, School of Electrical Engineering (EES).
    Krokos, Evangelos
    KTH, School of Electrical Engineering (EES).
    Centralized Vehicle License Management on ERTMS: Key Database and Communication between Server and RBC2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Today’s rail industry is under great demand. People will use trains even more in the future. Rail industry has to develop and integrate new systems towards a secure transportation system. One of these steps is investigated in this master thesis. Until now, many sensitive and vital data were transferred by using old methods like USB storage devices. In this master thesis, a new and secure way to store authentication keys in a central database is described as well as a secure way of communication between this database and the RBC entities. Different technologies are used and have as result the proposed goal. The creation of a database with PHP and the implementation of a server-client communication using TLS and HTTPS are described in this project. Improvements and future development of the project are discussed at the end.

  • Hallström, Louise
    KTH, School of Technology and Health (STH).
    Hallström, Louise
    KTH, School of Technology and Health (STH).
    Entreprenörers motivation till säkert arbete: Faktorer som påverkar beställarens främjande av en säkerhetskultur där entreprenörer är inkluderade2016Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Background: Working in the construction, paper and steel industry in Sweden means maintaining an occupation in a naturally hazardous environment. Engaging contractors in health and safety activities to achieve an improved occupational environment, and thereby raising the quality of production, can often be problematic due to a wide range of factors. These factors are being combated by Swedish companies which employees’ contractors Aim: The aim of this study is to examine which factors that could affect the improvement of the safety culture within a company which employees’ contractors. This study will focus on the client’s organization and the contractor’s participation. Method: A qualitative study was conducted including individual interviews with three companies in the construction, steel and paper industry in Sweden. One company from each field was selected, three managerial staff and three safety representatives interviewed from each. A thematic data analysis was conducted of the results. Results: The results indicate that the factors influencing the work of improving the safety culture in a company that employees’ contractors were as follows; management's approach to security, the organization of the security, cultural differences, control and monitoring of workplace conditions, participation, resources, communication and the contractor’s motivation to work safely. Discussion: A potential disadvantage of this study was that the results relate primarily to the client's perspective. Yet focusing on this perspective may also be seen as an advantage as it is the client who creates the safety culture that contractors should be a part of. The focus of the study was top-down analysis. If the study had instead been focused on a bottom-up perspective, the result would have been centered around strengthen the participation of contractors in how safety measures should be implemented, promoting their own desire to participate in a client’s safety culture. Conclusion: The conclusion of this study is that the promotion of a safety culture should be anchored within the management of a company. It is their approach to security and safety issues that is the deciding factor in promoting a safer workplace culture. Safety and security requirements should also be increasingly considered in the procurement of contractors, furthermore contractors should be included in security operations (including job training) and they should also be given the opportunity to report risks directly to the client's reporting system. This could promote both participation and communication within the company. Our final conclusion is that efforts should be to reduce the line between internal personnel and contractors on safety issues.

  • Public defence: 2017-01-31 10:00 FA32, Stockholm
    Pegonen, Reijo
    KTH, School of Engineering Sciences (SCI), Physics, Reactor Technology.
    Pegonen, Reijo
    KTH, School of Engineering Sciences (SCI), Physics, Reactor Technology.
    Development of an Improved Thermal-Hydraulic Modeling of the Jules Horowitz Reactor2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The newest European high performance material testing reactor, the Jules Horowitz Reactor, is under construction at CEA Cadarache research center in France. The reactor will support existing and future nuclear reactor technologies, with the first criticality expected at the end of this decade.

    The current/reference CEA methodology for simulating the thermalhydraulic behavior of the reactor gives reliable results. The CATHARE2 code simulates the full reactor circuit with a simplified approach for the core. The results of this model are used as boundary conditions in a three-dimensional FLICA4 core simulation. However this procedure needs further improvement and simplification to shorten the computational requirements and give more accurate core level data. The reactor’s high performance (e.g. high neutron fluxes, high power densities) and its design (e.g. narrow flow channels in the core) render the reactor modeling challenging compared to more conventional designs. It is possible via thermal-hydraulic or solely hydraulic Computational Fluid Dynamics (CFD) simulations to achieve a better insight of the flow and thermal aspects of the reactor’s performance. This approach is utilized to assess the initial modeling assumptions and to detect if more accurate modeling is necessary. There were no CFD thermal-hydraulic publications available on the JHR prior to the current PhD thesis project.

    The improvement process is split into five steps. In the first step, the state-of-the-art CEA methodology for thermal-hydraulic modeling of the reactor using the system code CATHARE2 and the core analysis code FLICA4 is described. In the second and third steps, a CFD thermal-hydraulic simulations of the reactor’s hot fuel element are undertaken with the code STAR-CCM+. Moreover, a conjugate heat transfer analysis is performed for the hot channel. The knowledge of the flow and temperature fields between different channels is important for performing safety analyses and for accurate modeling. In the fourth step, the flow field of the full reactor vessel is investigated by conducting CFD hydraulic simulations in order to identify the mass flow split between the 36 fuel elements and to describe the flow field in the upper and lower plenums. As a side study a thermal-hydraulic calculation, similar to those performed in previous steps is undertaken utilizing the outcome of the hydraulic calculation as an input. The final step culminates by producing an improved, more realistic, purely CATHARE2 based, JHR model, incorporating all the new knowledge acquired from the previous steps.

    The primary outcome of this four year PhD research project is the improved, more realistic, CATHARE2 model of the JHR with two approaches for the hot fuel element. Furthermore, the project has led to improved thermal-hydraulic knowledge of the complex reactor (including the hot fuel element), with the most prominent findings presented.

  • Järnberg, Emelie
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.), Mathematical Statistics.
    Järnberg, Emelie
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.), Mathematical Statistics.
    Dynamic Credit Models: An analysis using Monte Carlo methods and variance reduction techniques2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this thesis, the credit worthiness of a company is modelled using a stochastic process. Two credit models are considered; Merton's model, which models the value of a firm's assets using geometric Brownian motion, and the distance to default model, which is driven by a two factor jump diffusion process. The probability of default and the default time are simulated using Monte Carlo and the number of scenarios needed to obtain convergence in the simulations is investigated. The simulations are performed using the probability matrix method (PMM), which means that a transition probability matrix describing the process is created and used for the simulations. Besides this, two variance reduction techniques are investigated; importance sampling and antithetic variates.

  • Almgren, Lars
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.), Mathematical Statistics.
    Almgren, Lars
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.), Mathematical Statistics.
    Evaluation of HYDRA - A risk model for hydropower plants2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Vattenfall Hydro AB has more than 50 large scale power plants. In these power plants there are over 130 power generating units. The planning of renewals of these units is important to minimize the risk of having big breakdowns which inflict long downtime. Because all power plants are different Vattenfall Hydro AB started using a self developed risk model in 2003 to improve the comparisons between power plants. Since then the model has been used without larger improvements or validation.

    The purpose of this study is to evaluate and analyse how well the risk model has performed and is performing. This thesis is divided into five subsections where analyses are made on the input to the model, adverse events used in the model, the probabilities used in the model, risk forecasts from the model and finally trends for the periods the model has been used. In each subsection different statistical methods are used for the analyses.

    From the analyses it is clear that the low number of adverse events in power plants makes the usage of statistical methods for evaluating performance of Vattenfall Hydro AB’s risk model imprecise. Based on the results of this thesis the conclusion is made that if the risk model is to be used in the future it needs further improvements to generate more accurate results.

  • Wang, Pengfei
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Urban and Regional Studies.
    Wang, Pengfei
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Urban and Regional Studies.
    Wang, Jiayi
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Urban and Regional Studies.
    A Living Story of Parks: Urban History Research of Stockholmsskolan2016Independent thesis Advanced level (degree of Master (One Year)), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    Our thesis started with a continuous discovery of theory and observation. As a group work of landscape architect and architect, during the study of our Urbanism program, we were both curious about the urbanism theories within Europe. Among them, partly in terms of the landscape background, we were particularly interested in the theory of landscape urbanism and its practices in Europe. Spontaneously, this became our original thesis topic.

      However, after reading and collecting, we realized landscape urbanism theory was never as a main agenda in European academic world as in U.S. On the contrary, the role of landscape in urbanization is unignorable and has been examined for decades in Europe, which is one thing what landscape urbanists try to achieve. Moreover, during our reading of Swedish landscape and planning history, we noticed a series of significant parks which were built between 1930s-1950s, belong to a hardly forgotten design style named Stockholm School (Stockholmsskolan). This particular style and period of time is a fundamental part of Swedish landscape and planning history, deeply influenced the following park design as well as city planning in Stockholm. Almost all the parks of Stockholmsskolan nowadays become attractive spots for citizens gathering together, relaxing, and doing outdoor activities. Some of the parks are our personal favorite places in the city. Nevertheless, we choose this study not only to appreciate the significant parks but also to try to introduce them to other readers who might not be familiar with, especially to those who live outside of Europe with a different natural and cultural context.

      Our brief study could be the start of further research, and the tool of photography plays a key role in different stages of our thesis. As K.W. Gullers introduced Swedish lifestyle to the world through a photo about life in park seventy years ago, it would also be our honor if our booklet could interest readers to appreciate and rediscover the contemporary Swedish public space and urban life.

  • Lajoie-Mazenc, Thibaut
    KTH, School of Computer Science and Communication (CSC).
    Lajoie-Mazenc, Thibaut
    KTH, School of Computer Science and Communication (CSC).
    Increasing the robustness of the Bitcoincrypto-system in presence of undesirable behaviours2016Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Decentralised cryptocurrencies such as Bitcoin offer a new paradigm of electronic payment systems that do not rely on a trusted third-party. Instead, the peers forming the network handle the task traditionally left to the third-party, preventing attackers from spending twice the same resource, and do so in a publicly verifiable way through Bitcoin's main innovation, the blockchain. However, due to a lack of synchrony in the network, Bitcoin peers may transiently have conflicting views of the system: the blockchain is forked. This can happen purely by accident but attackers can also voluntarily create forks to mount other attacks on the system.

    In this work, we describe Bitcoin and its underlying blockchain protocol; we introduce a formal model to capture the normal operations of the system as well as forks and double-spending attacks. We use it to define Bitcoin's fundamental properties in terms of safety, liveness and validity.

    We present the current state of the system: first, we analyse some of the most prominent works that academia has produced between 2008 and 2016, as well as some promising leads to improve the system; then, we use the results of a measurement campaign to show that the size of the network is relatively stable because join and leave operations compensate each other, and that blocks propagate to most of the network in a matter of seconds. We further compare our results to those usually accepted by the community. We introduce a Bitcoin network simulator that we have implemented and present the experiment we have performed to validate it. Finally, we propose a modification to Bitcoin's operations that can prevent double-spending attacks and forks without giving up on its main ideological principles, decentralisation and the absence of source of trust.

  • DHAKA, AKASH KUMAR
    KTH, School of Computer Science and Communication (CSC).
    DHAKA, AKASH KUMAR
    KTH, School of Computer Science and Communication (CSC).
    Semi-Supervised Learning with Sparse Autoencoders in Automatic Speech Recognition2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This work is aimed at exploring semi-supervised learning techniques to improve the performance of Automatic Speech Recognition systems. Semi-supervised learning takes advantage of unlabeled data in order to improve the quality of the representations extracted from the data.The proposed model is a neural network where the weights are updated by minimizing the weighted sum of a supervised and an unsupervised cost function, simultaneously. These costs are evaluated on the labeled and unlabeled portions of the data set, respectively. The combined cost is optimized through mini-batch stochastic gradient descent via standard backpropagation.The model was tested on a phone classification task on the TIMIT American English data set and on a written digit classification task on the MNIST data set. Our results show that the model outperforms a network trained with standard backpropagation on the labelled material alone. The results are also in line with state-of-the-art graph-based semi-supervised training methods.

  • Brännlund, Håkan
    KTH, School of Electrical Engineering (EES), Electric power and energy systems.
    Brännlund, Håkan
    KTH, School of Electrical Engineering (EES), Electric power and energy systems.
    Network Programming Applied too Operation Planning of Hydrothermal Power Systems1986Doctoral thesis, monograph (Other academic)
    Abstract [en]

    The objective of the project was to develop models and methods suitable for computer implementation. In particular, this work has been devoted to generation scheduling of a power system with a sizeable amount. of hydro energy. Optimal operation planning of hydrothermal power systems aims at minimizing incurred production costs while supplying customer de­mand. The planning horizon may vary from one day to several years and the associated planning problems are categorized as short term, seasonal and long term operation planning. The topic of this thesis is short term operation planning.

    In this planning, it is necessary to use detailed models of the different parts of the power system. These include models of cas­caded reservoirs in a multi-river system as we11 as a representa­tion of the nonlinear generating characteristics of the hydro plants.

    he thermal generating units are modelled using linear production cost curves and by recognizing various technical constraints asso­ciated with the operation of these plants.

    Effects on the optimal operating strategy caused by interregional transmission capacity limitations are also accounted for by the model. These constraints are modelled to main1y affect the hydro plant operation.

  • Azeez Mohamed, Hussain
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Industrial Ecology.
    Azeez Mohamed, Hussain
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Industrial Ecology.
    Campos, Leonel
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Industrial Ecology.
    OIL SHALE ASH UTILIZATION IN INDUSTRIAL PROCESSES AS AN ALTERNATIVE RAW MATERIAL2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Oil shale is a fine-grained sedimentary rock with the potential to yield significant amounts of oil and combustible gas when retorted. Oil shale deposits have been found on almost every continent, but only Estonia, who has the 8th largest oil shale deposit in the world has continuously utilized oil shale in large scale operations. Worldwide, Estonia accounts for 80% of the overall activity involving oil shale, consuming approximately 18 million tons while producing 5–7 million tons of oil shale ash (OSA) annually. Since the amounts are quite significant, Estonia has made the choice to store OSA outdoors as ash heaps, which currently average a height of 45m and overall cover an area of approximately 20 km2. Oil shale is primarily composed of organic matter (15%–55%), low–magnesium calcite (>50%), dolomite (<10%–15%), and siliciclastic minerals (<10–15%). When oil shale is combusted in thermal power plants (TPP), temperatures as high as 1500˚C are reached; calcining CaCO3 into CaO in the process. It is the high CaO content (30%–50%; Free CaO 8%–23%) along with trace elements that makes OSA a threat to the environment; it is mainly the CaO and to a lesser degree the trace elements found in OSA that are exploited in this thesis. Currently, only about 5% of the 5–7 million tons of OSA produced annually is being utilized as an alternative raw material, mostly in the construction industry for the production of Portland cement. Multiple studies have been conducted on OSA in the past by various institutions in an attempt to increase its use in industry and reduce the negative environmental effects of storing large quantities of the highly alkaline material.

    This thesis primarily focuses on the treatment of acid mine drainage (AMD) and the production of precipitated calcium carbonate (PCC) using OSA. In Sweden, CaO is utilized in treating AMD in historical mine sites and in the production of PCC used in the paper industry. Oil shale ash has the potential to become a substitute for lime (CaO) utilized in various industries while Estonia transitions into renewable energy. The mining industry has been abundant in Sweden for hundreds of years, but the poor mining techniques of the past have led to a significant number of mines that require immediate AMD remediation. The Swedish EPA has declared that 600 mines currently need attention, which may cost approximately 2–3 billion SEK (232–350 million USD).

    1:200, 1:500, and 1:1000. All ratios yielded a pH greater than 10, most likely inducing the formation and precipitation of secondary minerals such as Schwertmannite and Ferrihydrite. The reduction of metallic cations such as Cu (maximum reduction 99.9%), Pb (99.8%), V (95.5%), Cd (99.9%), As (88.7%), and Ni (99.9%) from AMD waters was observed. The previously mentioned metallic cations most likely adsorbed and co-precipitated to the negatively charged surfaces of Schwertmannite and Ferrihydrite minerals. Metals such as Ba, Cr, and Sb were observed to leach out of OSA, increasing their concentrations in the treated AMD waters, but still within Swedish regulatory limits. Acid mine drainage treatment with OSA significantly reduces heavy metal concentrations; transforming the polluted waters from hazardous to non-hazardous waste (below Swedish leaching limit values). Precipitated calcium carbonate is utilized in many industries, such as in the production of paper, sealants and adhesives, paint, food, and pharmaceuticals. In Sweden, it is common for paper producers to have satellite PCC plants in close proximity so that CO2 (from the paper facility) is used in the carbonation of Ca(OH)2 to form PCC. The CaO in OSA may be mixed with H2O to form the required Ca(OH)2 for PCC production. Potentially replacing raw CaO currently purchased for the production of PCC.

    The conducted PCC production experiments directly carbonized vacuum filtered OSA leachate with a steady flow of CO2 gas to yield PCC. Precipitate obtained yielded 94%–99% of CaCO3 theoretical values. Throughout the carbonation process; OSA leachate’s pH began >12 and continuously decreased with time, maximum PCC production occurred at pH 9–10, and stabilized at pH 8.

    Although, the polymorphism and purity of the PCC is not known, the conducted experiments and previous studies on the topic indicate the feasibility of producing high quality PCC from OSA to be used in industry. Additionally, oil shale thermal power plants have the potential to produce PCC and other minerals by injecting flue gases into the highly alkaline (Ca(OH)2) water used to hydraulically transport OSA from the furnaces to ash heaps; reducing or seizing the production of alkaline leachates and emission of gases that currently contaminate the environment. Other applications for OSA were also investigated and reviewed, such as the lucrative extraction and refinement of rare earth elements. Estonian oil shale ash was tested for Ce, Nd, Y and Sc using ICP-MS and compared to Chinese OSA and selected European REE ores. Estonian OSA had the lowest concentrations of REEs in the comparison, nevertheless, previous studies have shown up to 80%-90% REE recovery via an acid leaching process. Rare earth recovery from OSA may be successful in the future if a practical and cost-effective method is developed. Reducing Europe’s dependence on China for REE.

  • Olof, Nilsson
    KTH, School of Electrical Engineering (EES), Electric power and energy systems.
    Olof, Nilsson
    KTH, School of Electrical Engineering (EES), Electric power and energy systems.
    Short Term Scheduling of Hydrothermal Power Systems With Integer Hydro Constraints1997Doctoral thesis, monograph (Other academic)
    Abstract [en]

    The thesis presents models for short term planning (24 hours) of a hyro dominated hydrothermal power system. The purpose of the models is to minimizae the system operation costs to provide a forecasted load and keep enough spinning reserve.

  • Public defence: 2017-01-27 13:00 Q2, StockholmFrid, Henrik
    Frid, Henrik
    On millimeter and submillimeter wave focal plane arrays implemented with MEMS waveguide switches2017Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis presents research towards enabling micromachined millimeter and submillimeter wave focal plane arrays (FPAs). The FPAs operate under the following principle: a switch network consisting of microelectromechanical (MEMS) switches, integrated with micromachined waveguides, is used to feed an array of antenna elements, located in the focal plane of a high-gain quasi-optical system. Hence, it is possible to switch between a set of narrow beams in different directions. Such beam steering systems are needed for future millimeter and submillimeter wave imaging and communication systems. The contributions to future MEMS-switchable FPAs presented here are organized in three papers, as described below.

    Paper I presents a criterion on the spacing between adjacent FPA elements which results in -3 dB overlap between the switched beams, for the special case when an extended hemispherical dielectric lens is used as the optical system. A key step towards this criterion is a closed-form relation between the scan angle and the FPA element's position, which results in an expression for the effective focal length of extended hemispherical lenses. A comparison with full-wave simulations demonstrates an excellent agreement with the presented theoretical results. Finally, it is shown that the maximum feasible FPA spacing when using an extended hemispherical lens is about 0.7 wavelengths.

    Paper II presents a numerical study of silicon-micromachined planar extended hemispherical lenses, with up to three matching regions used to reduce internal reflections. The effective permittivity of the matching regions is tailor-made by etching periodic holes in the silicon wafer. The optimal thickness and permittivity of the matching regions were determined using TRF optimization, in order to yield the maximum wide-band aperture efficiency and small side-lobes. We introduce a new matching region geometry, referred to as shifted-type matching regions, and it is demonstrated that using three shifted-type matching regions results in twice as large aperture efficiency as compared to using three conventional concentric-type matching regions.

    Paper III presents a submillimeter-wave single-pole single-throw (SPST) 500-750 GHz MEMS waveguide switch, based on a MEMS-reconfigurable surface inserted between two waveguide flanges. A detailed design parameter study is carried out to select the best combination of the number of horizontal bars and vertical columns of the MEMS-reconfigurable surface, for achieving a low insertion loss in the transmissive state and a high isolation in the blocking state. A method is presented to model the non-ideal electrical contacts between the vertical cantilevers of the MEMS surface, with an excellent agreement between the simulated and measured isolation. It is shown that the isolation can be improved by replacing an ohmic contact by a new, capacitive contact. The measured isolation of the switch prototype is better than 19 dB and the measured insertion loss is between 2.5 and 3 dB.

  • Callbo, Simon
    KTH, School of Electrical Engineering (EES).
    Callbo, Simon
    KTH, School of Electrical Engineering (EES).
    Solar Cell Current Simulator for a 3U Cube Satellite2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A spacecraft must survive the cold and dark space at the same time it needs to sustain every subsystem with sufficient amount of energy for each of the important scientific experiments on-board. In order for this to work the power system needs to acquire enough energy throughout its mission to power the space craft but also be able to store a sufficient amount of power to endure periods of eclipse and seasonal variations. One way of achieving this is by having solar cells covering the satellites surface which by the photo-voltaic effect converting light into energy. A concept on determining how much power is feasible and theoretically possible to acquire throughout a orbit presented in this thesis in the form of a software code which will simulate the spacecrafts orbit, the suns position on the sky, periods of eclipse, current generated of solar cells and evidently the amount of power. The Miniature Student Satellite, abbreviated MIST is the spacecraft under study. The orbital model is based on the Standard General Perturbations Satellite Orbit Model 4[3][37], the sun position vector is based on the Astronomical Almanac [8][28][4]. Simulations show that during fixed attitudes of the spacecraft in different orientations throughout a full year can generate a sufficient amount of power in order to survive. However in order to develop more exact results a power budget for each and every part of the satellite needs to be performed as well as hardware testing and integration with current software.

  • Habibollahzadeh, Hooshang
    KTH, School of Electrical Engineering (EES), Electric power and energy systems.
    Habibollahzadeh, Hooshang
    KTH, School of Electrical Engineering (EES), Electric power and energy systems.
    Application of Mathematical Programming to Short-Term Operation Planning of Hydrothermal Power System1984Doctoral thesis, monograph (Other academic)
    Abstract [en]

    The thesis contains the results of a reseach project on application of mathematical programming methods to short-term operation planning of large hydrothermal power systems. The project was aimed at devoeloping efficient solution techniques that are practially applicable to large systems. The problem is modeled as a large mixed integer program.

  • Raja, Anitha
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    Raja, Anitha
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Radio Systems Laboratory (RS Lab).
    A Coordination Framework for Deploying Hadoop MapReduce Jobs on Hadoop Cluster2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Apache Hadoop is an open source framework that delivers reliable, scalable, and distributed computing. Hadoop services are provided for distributed data storage, data processing, data access, and security. MapReduce is the heart of the Hadoop framework and was designed to process vast amounts of data distributed over a large number of nodes. MapReduce has been used extensively to process structured and unstructured data in diverse fields such as e-commerce, web search, social networks, and scientific computation. Understanding the characteristics of Hadoop MapReduce workloads is the key to achieving improved configurations and refining system throughput. Thus far, MapReduce workload characterization in a large-scale production environment has not been well studied.

    In this thesis project, the focus is mainly on composing a Hadoop cluster (as an execution environment for data processing) to analyze two types of Hadoop MapReduce (MR) jobs via a proposed coordination framework. This coordination framework is referred to as a workload translator. The outcome of this work includes: (1) a parametric workload model for the target MR jobs, (2) a cluster specification to develop an improved cluster deployment strategy using the model and coordination framework, and (3) better scheduling and hence better performance of jobs (i.e. shorter job completion time). We implemented a prototype of our solution using Apache Tomcat on (OpenStack) Ubuntu Trusty Tahr, which uses RESTful APIs to (1) create a Hadoop cluster version 2.7.2 and (2) to scale up and scale down the number of workers in the cluster.

    The experimental results showed that with well tuned parameters, MR jobs can achieve a reduction in the job completion time and improved utilization of the hardware resources. The target audience for this thesis are developers. As future work, we suggest adding additional parameters to develop a more refined workload model for MR and similar jobs.

  • Eliasson, Jonas
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Eliasson, Jonas
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Transport Planning, Economics and Engineering.
    Problemstyrd planering: en förklaring till att effektivitet spelar så liten roll för valet av transportåtgärder.2015In: Ressursbruk i transportsektoren – noen mulige forbedringer. / [ed] Morten Welde, James Odeck, Oslo: Concept , 2015Chapter in book (Refereed)
  • Public defence: 2017-02-24 10:15 99133, Gävle
    Amin, Shoaib
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Amin, Shoaib
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Characterization and Linearization of Multi-band Multi-channel RF Power Amplifiers2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The World today is deeply transformed by the advancement in wireless technology. The envision of a smart society where interactions between physical and virtual dimensions of life are intertwined and where human interaction is mediated by machines, e.g., smart phones, demands increasingly more data traffic. This continual increase in data traffic requires re-designing of the wireless technologies for increased system capacity and flexibility. In this thesis, aspects related to behavioral modeling, characterization, and linearization of multi-channel/band power amplifiers (PAs) are discussed.

    When building a model of any system, it is advantageous to take into account the knowledge of the physics of the system and include into the model. This approach could help to improve the model performance. In this context, three novel behavioral models and DPD schemes for nonlinear MIMO transmitters are proposed.

    To model and compensate distortions in GaN based RF PAs in presence of long-term memory effects, novel models for SISO and concurrent dual-band PAs are proposed. These models are based on a fixed pole expansion technique and have infinite impulse response. They show substantial performance improvement. A behavioral model based on the physical knowledge of the concurrent dual-band PA is derived, and its performance is investigated both for behavioral modeling and compensation of nonlinear distortions.

    Two-tone characterization is a fingerprint method for the characterization of memory effects in dynamic nonlinear systems. In this context, two novel techniques are proposed. The first technique is a dual two-tone characterization technique to characterize the memory effects of self- and cross-modulation products in concurrent dual-band transmitter. The second technique is for the characterization and analysis of self- and cross-Volterra kernels of nonlinear 3x3 MIMO systems using three-tone signals.

  • Public defence: 2017-02-17 13:00 Q2, Stockholm
    Yajnanarayana, Vijaya Parampalli
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Yajnanarayana, Vijaya Parampalli
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Ultra Wideband: Communication and Localization2017Doctoral thesis, monograph (Other academic)
    Abstract [en]

    The first part of this thesis develops methods for UWB communication. To meet the stringent regulatory body constraints, the physical layer signaling technique of the UWB transceiver should be optimally designed. We propose two signaling schemes which are variants of pulse position modulation (PPM) signaling for impulse radio (IR) UWB communication. We also discuss the detectors for the signaling schemes and evaluate the performance of these detectors.  IR-UWB can be used for precise range measurements as it provides a very high time resolution. This enables accurate time of arrival (TOA) estimations from which precise range values can be derived. We propose methods which use range information to arrive at optimal schedules for an all-to-all broadcast problem. Results indicate that throughput can be increased on average by three to ten times for typical network configurations compared to the traditional methods. Next, we discuss hypothesis testing in the context of UWB transceivers. We show that, when multiple detector outputs from a hardware platform are available, fusing the results from them can yield better performance in hypothesis testing than relying on a single detector output. In the second part of this thesis, the emphasis is placed on localization and joint estimation of location and communication parameters. Here, we focus on estimating the TOA of the signal. The wide bandwidth of the UWB signal requires high speed analog to digital converts (ADC) which makes the cost of the digital transceivers prohibitively high. To address this problem, we take two different strategies. In the first approach, we propose a multichannel receiver with each channel having a low-cost energy detector operating at a sub-Nyquist rate. In the second approach, we consider a compressive sampling based technique. Here, we propose a new acquisition front end, using which the sampling rate of the ADC can be significantly reduced. We extended the idea of compressive sampling based TOA estimation towards joint estimation of TOA and PPM symbols. Here, two signaling methods along with the algorithms are proposed based on the dynamicity of the target. They provide similar performance to the ML based estimation, however with a significant savings in the ADC resources.

  • yagdiran, Eren
    KTH, School of Information and Communication Technology (ICT).
    yagdiran, Eren
    KTH, School of Information and Communication Technology (ICT).
    Using Bitcoin for Fun and Profit2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Botnets, in other means zombie computers that await for instructions to execute, are the greatest threat in the internet today. They are one of the leading sources of online crime. Criminals are able to take advantage of using botnets and threaten online businesses, organizations or any entity in the internet. Criminals design and implement botnets in a complex way in order to hide their identities. Most notably the fact that criminals build command-and-control (C&C) infrastructures to manage their botnets.

    A botnet command-and-control mechanism (C&C) can be designed in various ways. The key principle behind designing a C&C mechanism is anonymity. Hence, criminals can propagate their instructions to botnets without revealing their identities. Since every new C&C mechanism increases the bar of anonymity, it is getting harder to trace and analyze botnets. In this thesis, we designed and implemented a C&C mechanism, btc-botnet, that runs over Bitcoin network. Btcbotnet has significant features over existing C&C mechanisms such as anonymity and resistance by its nature. We built a library that allows to use Bitcoin network as an underlying infrastructure for C&C mechanism. We evaluate our work and show that its feasibility in terms of metrics such as response time, confirmation time and fees.

  • Nilsson, Isak
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH, Music Acoustics.
    Nilsson, Isak
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH, Music Acoustics.
    Electroglottography in Real-Time Feedback for Healthy Singing2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This master thesis describes early attempts at using electroglottography (EGG) to capture such changes in vocal fold vibration patterns that could be of interest to teachers of contemporary commercial music. After initial explorations, focus is placed on detecting potentially detrimental phonation; more specifically on the pressed quality often associated with loud singing in high register (belting). FonaDyn, a program written in the SuperCollider language, is used to detect pressedness using an algorithm based on K-means clustering of Fourier components of EGG cycles. Results indicate that pressedness affects phonation in ways detectable using EGG. Changes caused by pressedness seem to vary between registers and this variation is similar between subjects. Detection of pressedness in a subject is quite successful when training the algorithm on the same subject, but not always across subjects.

  • Yang, Yang
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Computational Thermodynamics.
    Yang, Yang
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Computational Thermodynamics.
    Investigation of vanadium-containing oxide systems: CALPHAD and experiments2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Fundamental studies on thermodynamic properties of vanadium-containing oxides systems are essential to understand practical vanadium metallurgical process. The CALPHAD technique is here applied to the thermodynamic modelling of the V-O, Ca-V-O and Ti-V-O systems. The compound energy formalism is used for all the solution phases. All optimization processes and calculations are performed using the Thermo-Calc software package. The present work attempts to develop a self-consistent thermodynamic database of all phases in the studied systems. The obtained datasets can be used to calculate thermodynamic properties, stable as well as metastable phase equilibria and driving forces for oxidation etc.

    Steelmaking slag is an important secondary source for vanadium extraction. The phase relationships and vanadium distribution in the CaO-SiO2-MgO-V2O3-Al2O3 synthetic slags, whose compositions were chosen based on the relevance to the steel producers, are also studied. Phase equilibria in the temperature range of 1773 to 1823 K at oxygen partial pressure of 10-10 bar and 0.21 bar were characterized.

    An investigation of the volatilization of vanadium oxide was also carried out in the present work. Isothermal evaporation of vanadium pentoxide in the temperature range between 1723 and 1873 K was investigated by Thermogravimetric Analysis under different oxygen partial pressures, viz. oxygen, air or CO2. The Arrhenius activation energy for the evaporation reaction in various atmospheres was calculated from the experimental results. A mathematical model was developed to describe the kinetics of the evaporation process. Evaporation coefficients and enthalpies in various atmospheres were also estimated. The present results may have some implications in recovering vanadium from different vanadium-bearing sources.

  • Woidt, Hendrik
    KTH, School of Information and Communication Technology (ICT).
    Woidt, Hendrik
    KTH, School of Information and Communication Technology (ICT).
    Hardware Synthesis in ForSyDe2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    There have been numerous e orts in the development of functional hardware description languages over the past years. In this thesis project the design space for embedded domain specic languages for hardware synthesis in Haskell is explored by comparing the approaches of two di erent language implementations.

    This report contains an introduction to the fundamental concepts for modeling hardware in a functional style and the core concepts of implementing deep embedded languages. Based on this, the architectures of ForSyDe.Deep and Cash are examined in order to nd their strengths and weaknesses. The results are applied to the implementation of translation of data-parallel higher order functions in ForSyDe.Deep.

    The implementation of higher order functions has shown that the lack of type information available for the translation of process functions in the current implementation of ForSyDe.Deep is the limiting factor for achieving a higher level of abstraction within process functions through polymorphism or higher order functions. This does not diminish the approach of ForSyDe though as the real power lies in the abstraction provided by the process network.

  • Zaki, Youssef
    KTH, School of Information and Communication Technology (ICT).
    Zaki, Youssef
    KTH, School of Information and Communication Technology (ICT).
    An Embedded Multi-Core Platform for Mixed-Criticality Systems: Study and Analysis of Virtualization Techniques2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The common availability of multiple processors in modern CPU devices and the need to reduce cost of embedded systems has created a drive for integrating functionalities from different parts of a system into a single Multi- Processor System-on-Chip (MPSoC) device. As a result, system resources are shared amongst the critical and non-critical components of the system, which results in a mixed-criticality system (MCS). An example of a MCS is to combine an airbag control unit with the infotainment system of a car, in such a case, both components must be certified unless an isolation mechanism that can prevent the non-critical to interfere with the critical subsystems is implemented. This isolation can be achieved via spatial and temporal partitioning of system resources, such as static mapping of CPUs to critical tasks, memory and IO virtualization, and time domain multiplexing of applications.

    System isolation is currently achievable through virtualization techniques, and is commonly used in data centers and personal computers. Recently, virtualization solutions have been emerging for embedded systems in order to cope with the increased design complexity, the stringent non-functional requirements, and to facilitate the certification process of MCS. The achieved performance, safety, security, and robustness in a virtualized system depends on the virtualization architecture and hardware platform.

    This thesis work performs state-of the art research in the field of mixedcriticality embedded systems with a focus on virtualization of embedded systems. As a result, a deep study of virtualization architectures, and open-source virtualization solutions is conducted in order to understand the consequences of using this technology in MCS. The work is concluded with a design and implementation of mixed-criticality embedded system that leverages the hardware capabilities of the target device (Zynq-7000 all programmable SoC), and contributes to the Living Lab WP7 of the EMC2 project.

  • Qu, An
    et al.
    Qu, An
    Zhang, Cheng
    KTH, School of Computer Science and Communication (CSC), Computer Vision and Active Perception, CVAP.
    Ackermann, Paul
    Kjellström, Hedvig
    KTH, School of Computer Science and Communication (CSC), Computer Vision and Active Perception, CVAP.
    Bridging Medical Data Inference to Achilles Tendon Rupture Rehabilitation2016Conference paper (Refereed)
  • Zhang, Cheng
    et al.
    KTH, School of Computer Science and Communication (CSC), Computer Vision and Active Perception, CVAP.
    Zhang, Cheng
    KTH, School of Computer Science and Communication (CSC), Computer Vision and Active Perception, CVAP.
    Mandt, Stephan
    Kjellström, Hedvig
    KTH, School of Computer Science and Communication (CSC), Robotics, perception and learning, RPL.
    Balanced Population Stochastic Variational Inference2016Conference paper (Refereed)
  • Zhang, Cheng
    et al.
    KTH, School of Computer Science and Communication (CSC), Computer Vision and Active Perception, CVAP.
    Zhang, Cheng
    KTH, School of Computer Science and Communication (CSC), Computer Vision and Active Perception, CVAP.
    Kjellström, Hedvig
    KTH, School of Computer Science and Communication (CSC), Robotics, perception and learning, RPL.
    Bertilson, Bo C.
    Diagnostic Prediction Using Discomfort Drawings2016Conference paper (Refereed)
  • Zhang, Cheng
    et al.
    KTH, School of Computer Science and Communication (CSC), Computer Vision and Active Perception, CVAP.
    Zhang, Cheng
    KTH, School of Computer Science and Communication (CSC), Computer Vision and Active Perception, CVAP.
    Kjellström, Hedvig
    KTH, School of Computer Science and Communication (CSC), Robotics, perception and learning, RPL.
    Ek, Carl Henrik
    Bertilson, Bo C.
    Diagnostic Prediction Using Discomfort Drawing with IBTM2016Conference paper (Refereed)
    Abstract [en]

    In this paper, we explore the possibility to apply machine learning to make diagnostic predictions using discomfort drawings. A discomfort drawing is an intuitive way for patients to express discomfort and pain related symptoms. These drawings have proven to be an effective method to collect patient data and make diagnostic decisions in real-life practice. A dataset from real-world patient cases is collected for which medical experts provide diagnostic labels. Next, we use a factorized multimodal topic model, Inter-Battery Topic Model (IBTM), to train a system that can make diagnostic predictions given an unseen discomfort drawing. The number of output diagnostic labels is determined by using mean-shift clustering on the discomfort drawing. Experimental results show reasonable predictions of diagnostic labels given an unseen discomfort drawing. Additionally, we generate synthetic discomfort drawings with IBTM given a diagnostic label, which results in typical cases of symptoms. The positive result indicates a significant potential of machine learning to be used for parts of the pain diagnostic process and to be a decision support system for physicians and other health care personnel.

  • Arnesson, Jennifer
    KTH, School of Engineering Sciences (SCI), Physics, Reactor Physics.
    Arnesson, Jennifer
    KTH, School of Engineering Sciences (SCI), Physics, Reactor Physics.
    Numerical Modeling of Radioactive Release Implemented for Loss of Coolant Accident, Evaluated using Latin Hypercube Sampling2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • Eliasson, Linda
    KTH, School of Engineering Sciences (SCI), Physics.
    Eliasson, Linda
    KTH, School of Engineering Sciences (SCI), Physics.
    Detector Cell Performance Tests and Determination of Polarisation Characteristics for PoGO+2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • Public defence: 2016-12-19 10:00 Kollegiesalen, Stockholm
    Long, Mengni
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Long, Mengni
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    On the Attachment of Lightning Flashes to Wind Turbines2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The work presented in this thesis aims at investigating the attachment of lightning flashes to wind turbines. Modern wind turbines are highly exposed to lightning strikes, due to the increase of their height and the rotation of the blades. Upward lightning is the dominant mechanism of lightning strikes to them. Therefore, this study evaluates the initiation of the initial upward leader discharge and the process of lightning attachment of dart leaders taking place prior to the first return stroke in upward flashes.

    This work extends the self-consistent leader inception and propagation model (SLIM) to evaluate the lightning attachment of dart and dart-stepped leaders to grounded objects. SLIM was originally proposed to evaluate the lightning attachment of stepped leaders. Unlike the well-studied lightning attachment of stepped leaders, upward connecting leaders initiated in response to dart and dart-stepped leaders develop under a significantly faster change of the ambient electric field. Additionally, these connecting leaders could develop in warm air pre-conditioned by the previous strokes in the same flash. An analytical expression to evaluate the charge required to thermalize the connecting leader per unit length is also developed in the extended model. This model is validated through the analysis of three attachment events recorded in rocket-triggered lightning experiments. Good agreement between the predicted properties of the upward leaders and the measurements has been found. The model is utilized to evaluate the different conditions where connecting leaders can develop prior to the return strokes in upward lightning.

    The extended model of SLIM is also applied to study the interception of lightning dart leaders by upward connecting leaders initiated from wind turbines. The evaluation considers the influence of the return stroke peak current, the blade rotation and wind on the attachment of lightning dart leaders to wind turbines. The probability of lightning strikes to the receptors along the blade and on the nacelle is calculated for upward lightning flashes. It is shown that the lightning attachment of dart leaders is a mechanism that can explain the lightning damages to the inboard region of the blades (more than 10 meters from the tip) and the nacelle of wind turbines.

    Furthermore, the critical stabilization electric field required to initiate upward lightning from wind turbines is evaluated for both ‘self-initiated’ and ‘other-triggered’ upward flashes. The calculation shows that the stabilization electric field of an operating wind turbine periodically changes due to the rotation of its blades.  The initiation of upward lightning is greatly facilitated by the electric field change produced by nearby lightning events. However, the rate of rise of the electric field only has a weak impact on the stabilization electric field. The evaluation of the stabilization electric field provides essential information needed for the estimation of the incidence of upward lightning to wind turbines.

  • Yang, Yuecheng
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.), Optimization and Systems Theory.
    Yang, Yuecheng
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.), Optimization and Systems Theory.
    Self-organization and Intervention of Nonlinear Multi-agent Systems2016Doctoral thesis, monograph (Other academic)
    Abstract [en]

    This dissertation concerns the self-organization behaviors in different types of multi-agent systems, and possible ways to apply interventions on top ofthat to achieve certain goals. A bounded confidence opinion dynamics modelis considered for the first two papers. Theoretical analysis of the model isperformed and modifications of the model are given so that it will have better properties in some aspect. Leader-follower based models are studied in the third to fifth papers where various optimal control problems are considered. Different methods such as Pontryagin minimum principle and dynamic programming are used to solve those optimal control problem. For complex problems, one may only get approximate solutions or suboptimal solutions.In Paper A and Paper B, we consider the continuous-time Hegselmann-Krause (H-K) model and its variations and target the problem of reaching consensus. A sufficient condition on the initial opinion distribution is givento guarantee consensus for the original continuous-time H-K model. A modified model is provided and proven to be able to lead a larger range of initial opinions to synchronization. An H-K model with an exo-system is also studied where sufficient conditions on the exo-system are given for the purpose of consensus.In Paper C and Paper D, optimal control problems with leader-followerbased multi-agent systems are discussed. Analytic solutions are derived if the dynamics is linear by applying Pontryagin minimum principle. For generalnon-linear leader-follower interactions, we provide a method that use sstatistic moments of the follower crowd to approximate the optimal control.The dynamic programming approach is used and certain approximation ofthe Hamilton-Jacobi-Bellman equations is needed. The computational burdenis so heavy that model predictive control method is required in practical applications.In Paper E, we apply a similar method to the approach used in PaperD to target a pollutant elimination problem. It implies that we can use themethod to attack optimal control problem with partial differential equation constraints by discretization in space. The dimension of the discretization is not related to the computational complexity since only the statistic moments are needed.

  • Public defence: 2016-12-20 10:00 F3, Stockholm
    Grytsan, Andrii
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.), Biomechanics.
    Grytsan, Andrii
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.), Biomechanics.
    Abdominal aortic aneurysm inception and evolution - A computational model2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Abdominal aortic aneurysm (AAA) is characterized by a bulge in the abdominal aorta. AAA development is mostly asymptomatic, but such a bulge may suddenly rupture, which is associated with a high mortality rate. Unfortunately, there is no medication that can prevent AAA from expanding or rupturing. Therefore, patients with detected AAA are monitored until treatment indication, such as maximum AAA diameter of 55 mm or expansion rate of 1 cm/year. Models of AAA development may help to understand the disease progression and to inform decision-making on a patient-specific basis. AAA growth and remodeling (G&R) models are rather complex, and before the challenge is undertaken, sound clinical validation is required.

    In Paper A, an existing thick-walled model of growth and remodeling of one layer of an AAA slice has been extended to a two-layered model, which better reflects the layered structure of the vessel wall. A parameter study was performed to investigate the influence of mechanical properties and G&R parameters of such a model on the aneurysm growth.

    In Paper B, the model from Paper A was extended to an organ level model of AAA growth. Furthermore, the model was incorporated into a Fluid-Solid-Growth (FSG) framework. A patient-specific geometry of the abdominal aorta is used to illustrate the model capabilities.

    In Paper C, the evolution of the patient-specific biomechanical characteristics of the AAA was investigated. Four patients with five to eight Computed Tomography-Angiography (CT-A) scans at different time points were analyzed. Several non-trivial statistical correlations were found between the analyzed parameters.

    In Paper D, the effect of different growth kinematics on AAA growth was investigated. The transverse isotropic in-thickness growth was the most suitable AAA growth assumption, while fully isotropic growth and transverse isotropic in-plane growth produced unrealistic results. In addition, modeling of the tissue volume change improved the wall thickness prediction, but still overestimated thinning of the wall during aneurysm expansion.

  • Larsson Lagerås, Max
    et al.
    KTH, School of Technology and Health (STH).
    Larsson Lagerås, Max
    KTH, School of Technology and Health (STH).
    Hedman Johnson, Martin
    KTH, School of Technology and Health (STH).
    Prediktion av väntetid på akutmottagning2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Introduktion

    Lång väntetid för Stockholms sjukhusbundna akutmottagningar är ett stort problem, samt stor spridning av väntetider mellan de olika mottagningarna. Prediktion av väntetid för Stockholms akutmottagningar är av värde för personer vid val av mottagning och kan i längden resulterai en spridning av patientbelastningen på Stockholms sjukhus.

    Metod

    Tidskoder och prioritetsklassificering för besökare på en av Stockholms akutmottagningar användes för att utreda linjära förhållanden mellan kö och väntetid, utifrån vilka prediktionsmodeller togs fram.

    Resultat

    Bästa linjära prediktiva metod ger ett medelfel på 86 minuter. Akutmottangningsköer uppvisar ett ickelinjärt förhållande till väntetider och följer inte dess formellt definierade prioritetsordning.

    Slutsats

    Djupare förståelse för hur akutmottagningsköer är organiserade i praktiken behövs för prediktion av väntetid som är tillräckligt precis för att vara av värde vid val av mottagning.

  • Nauclér, Maria
    KTH, School of Technology and Health (STH), Health Systems Engineering, Ergonomics.
    Nauclér, Maria
    KTH, School of Technology and Health (STH), Health Systems Engineering, Ergonomics.
    Exponering för kolloidala nanopartiklar av kiseldioxid i arbetsmiljö: Litteraturstudie och riskbedömning vid ett kemiföretag2016Independent thesis Advanced level (degree of Master (One Year)), 40 credits / 60 HE creditsStudent thesis
    Abstract [en]

    Abstract

    The purpose of this master thesis was to investigate the occupational health effects concerning nanoparticles of colloidal silica at a Swedish company that conducts chemical production. The study was performed at a company that manufactures a product, Product A, whose raw material, Raw material B, contains the concerned nanoparticles. The goal was to reduce health risks and to promote a good working environment.

     

    Methods used included literature studies, studies of safety data sheets, assessment of earlier measurements taken by the company, interviews and observations as well as a risk assessment method and tool.

     

    A research study about the potential health concerns regarding nanoparticles of colloidal silica indicated a cytotoxic effect on tested human alveolar epithelial cells. Although these were the findings of this study, it was also noted that too little data was present in order to be able to make any conclusions on effects of human exposure. One study showed that it was possible for nanoparticles to penetrate the skin. Other studies did not indicate adverse effects. In summary, there is too small an amount of data and knowledge gaps exist around health the effects. Therefore it is reasonable to apply the precautionary principle.

     

    Interviews with the workers and observations of the operations showed that the manufacturing process to a large extent was a closed process and that the workers’ exposure of nanoparticles mostly occurred when; transferring the product to transportation containers, cleaning, changing of filters and sampling of the product. A risk assessment of the working environment in the production of Product A was performed. Due to previous precautionary measures taken by the company it was not likely that any larger exposure was present. A number of additional measures were developed and prioritized in order to further reduce the workers’ exposure risks and promote a good working environment. The most important measure was to reduce the spillage of concentrated Product A and dilute Raw material B. Several of the measures were non-costly and quick to implement.

     

     

     

     

  • Carniello, Vera
    KTH, School of Technology and Health (STH).
    Carniello, Vera
    KTH, School of Technology and Health (STH).
    Tailoring interactions betweendegradable polymers and proteins,exploiting nanodiamond particlesand Quartz Crystal Microbalance2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Quartz Crystal Microbalance (QCM) is a sensitive and effective technique to analyze mass changes at the interface between a solid material and a liquid environment. In this Master thesis, QCM was employed for evaluating the interactions between selected degradable polymers and nanodiamond particles (nDP), fibronectin and the growth factor BMP-2.

     

    Many parameters must be adapted to allow QCM measurements involving degradable polymers. These parameters were then tailored to allow QCM measurements with PLA, poly(LLA-co-CL), poly(TMC-D-LA) and PS.

     

    Moreover, QCM provides quantitative measurements of protein adsorption on degradable polymers. The behavior of PLA and poly(LLA-co-CL) was further evaluated and compared with respect to protein adsorption. This behavior was demonstrated to be different for the two polymers considered and to be dependent on protein concentration in solution.

     

    Eventually, exploiting QCM it was also possible to assess the relationship between nDP and the adsorption of fibronectin and BMP-2 onto PLA and poly(LLA-co-CL).

  • Cholaraju Narasaraju, Vignesh
    KTH, School of Information and Communication Technology (ICT).
    Cholaraju Narasaraju, Vignesh
    KTH, School of Information and Communication Technology (ICT).
    Impact of Extended DRX Cycles on Battery Lifetimes and UE Reachability2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Several UE energy consumption optimization techniques have been proposed for Machine Type Communication (MTC) devices. Extended Discontinuous Reception (eDRX) in idle mode is one such technique wherein an UE in idle mode wakes up only during its Paging Occasion (PO) to monitor paging messages from eNodeB (eNB). The PO is located within a Paging frame (PF). The PF is a function of System Frame Number (SFN) cycle of eNB. The paging messages may be sent asynchronously from multiple eNBs to a UE. Due to asynchronous operation of eNBs, SFN takes on different values at a given point in time and therefore a paging message is transmitted at different points in time from different eNBs. Due to this SFN misalignment between eNBs, an idle mode UE might receive and respond to the same paging message from different eNBs and/or miss a PO and thus the paging message. Due to this spread in time of SFN and PO, the actual handling of paging message by the UE becomes inefficient leading to increased UE energy consumption and decreased reachability. These issues, resulting from paging handling, will get amplified further if DRX period is extended longer (eDRX).

    In this study, we investigate the impact of eDRX cycles and mobility related parameters such as UE speed, cell size and size of SFN misalignment between eNBs on UE energy consumption, use of network resources and UE reachability. Receiving and responding to the same paging message results in increased energy consumption for UE and increased signaling between UE and the network. Missing a PO results in delayed paging reception and hence decreases UE reachability. As the DRX cycle lengths are increased from existing maximum of 2.56 seconds to 10.24 seconds and beyond, we see a reduction in UE energy consumption by more than 90%, but the network signaling and the delay to reach the UE increases linearly as a function of the DRX cycle length. We observe that the number of duplicate paging message receptions/missed POs is minuscule for DRX cycle lengths below 10.24 sec. At DRX cycle length of 10.24 seconds, UEs travelling across 500 m cell radius at speeds of 3, 50, 100 km/h the percentage of duplicate paging receptions are 0.07, 0.11, and 0.15 respectively. This duplicate paging message reception increases the UE energy consumption by 2.31, 6.15 and 12 percent of the total energy units respectively. Similarly, UE misses nearly 0.34, 0.39, and 0.405 percent of the total POs respectively. Depending on the number of consecutive PO misses, the UE reachability decreases. But by reducing the size of SFN misalignment between eNBs, we see that it’s possible to increase the reachability for UEs in eDRX. Further we have proposed solutions based on our analytical study to avoid duplicate paging message reception by UE, increase UE reachability and also reduce UE energy consumption using a windowing technique. We conclude that when a UE is configured with eDRX cycles, the tradeoff between battery lifetimes and UE reachability is based on mobility characteristics and service requirements.

  • Hasselgren, Björn
    Timbro, Sweden.
    Hasselgren, Björn
    Timbro, Sweden.
    Politiken - en affärsverksamhet med särskilda förtecken2016In: Ekonomisk Debatt, ISSN 0345-2646, Vol. 44, no 6, 63-66 p.Article, book review (Other academic)
  • Public defence: 2016-12-19 13:00 4055, Stockholm
    Rådestad, Sofie
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Urban and Regional Studies.
    Rådestad, Sofie
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Urban and Regional Studies.
    Engagement in urban planning as a consequence of trust: an explorative study of the Slussen redevelopment project opposition2016Licentiate thesis, monograph (Other academic)
    Abstract [en]

    This study is about the phenomenon of trust as applied in urban planning processes. The study views this concept through the lens of “the opposition” – the dissenting voices to the official narratives of urban planning projects. The main focus in this context is Slussen in Stockholm, Sweden, which is a majorly important redevelopment project as well as a source of heated debate. The methodological approach is qualitative research. The data collection relies on interviews and a discourse analysis of text and language. The interviewees are chosen based on their experience of, or participation in, opposition against the Slussen redevelopment project. The theoretical literature and the interviews are analysed through the theoretical framework of Erik Blennberger’s six analytical themes of trust. This enables a systematic detached approach to analysing the subjective interviews as well enabling a comparison between empirical evidence and relevant theoretical literature. This process resulted in seven categories of (dis)trust emerging from the interview material, which in turn resulted in the conclusion that, based on the study’s main findings three factors were the possible reasons behind the opposition of the Slussen redevelopment project: (1) Slussen as a unique space, (2) Debate character, (3) Authority. Based on these empirical findings and their comparison to the theoretical literature, the study concludes that trust depends on people’s perceptions of trustworthy actions of those who initiate change. That by exploring trust in the statements of oppositional networks over time it is possible to better understand issues regarding implementation of urban planning projects. 

  • Andersson, Lisa
    KTH, School of Technology and Health (STH), Health Systems Engineering, Ergonomics.
    Andersson, Lisa
    KTH, School of Technology and Health (STH), Health Systems Engineering, Ergonomics.
    Det passar inte alla: Arbetstillfredställelse, produktivitet och stress i kontorslandskap2016Independent thesis Advanced level (degree of Master (One Year)), 40 credits / 60 HE creditsStudent thesis
    Abstract [en]

    The open-plan offices at Boliden has been renovated. The company wanted an evaluation of what the employees thought about the physical work environment in the new offices. The company also wanted the study to present improvement for deficiencies in the physical environment.

     

    The aim of this study was to identify positive and negative aspects of the physical working environment factors and to identify correlation between the physical work environment factors and job satisfaction, productivity and stress. A second purpose was also to present some improvement for the physical work environment. A part of the questionnaire was to evaluate if there existed any difference between the sexes regarding the physical work environment. To examine these aspects this study used a questionnaire as well a system group seminar to develop possible improvements.

     

    The results from the questionnaire show that the employees were pleased with the ventilation, the furniture’s functionality and the aesthetics of the office. The questionnaire also found dissatisfaction with glare, outlook and temperature but mostly the audial privacy in the office.

     

    Previous studies have shown that there is a correlation between physical work environment factors, job satisfaction and productivity but inconsistent evidence for work environment and stress. This study showed significant relationship between the auditory privacy, job satisfaction and productivity but not between auditory privacy and stress, which corresponds to the previous studies.

     

    The improvements presented at the system group seminar was to introduce guidelines to reduce noise and divide the office into smaller offices. To improve the auditory privacy this study suggests that a combination of redeploying employees in the open-plan office, dividing the office in to smaller office areas and introduces guidelines of how the employees should behave in the open-plan office.

  • Myhrberg, Therese
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Environmental Strategies Research (fms).
    Myhrberg, Therese
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Environmental Strategies Research (fms).
    Målkonflikter inom kommunal Översiktsplanering och Miljöbedömning2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    Alltsedan målstyrning infördes inom svensk beslutsfattning och förvaltning har målkonflikter varit ett faktum som politiker och tjänstemän måste ta ställning till på ett eller annat sätt. En målkonflikt uppstår då uppfyllelsen av ett samhällsmål motverkar uppfyllelsen av ett annat samhällsmål. Det kan exempelvis röra sig om kontrasterande mål gällande nybyggnation och att samtidigt bevara natur- och kulturvärden. Forskningsprojektet SPEAK, som denna studie har koppling till, och som handlar om att identifiera brister och förbättringsåtgärder inom svensk miljöbedömning, ser målkonfliktshantering inom kommunal planering som ett bristområde som behöver förbättras, inte minst genom att erhålla ökad kunskap om nuläget.

    Denna studie har till syfte att utreda hur målkonflikter identifieras och hanteras på kommunal nivå i Sverige inom ramen för kommunal översiktsplanering med tillhörande miljökonsekvensbeskrivning, samt att ge några rekommendationer för hur målkonfliktshantering skulle kunna förbättras. Studien baseras på en textanalys gjord utifrån plandokument från 80 kommuner, samt en mer djupgående intervjustudie med tjänstemän som arbetat med översiktsplanerna på tre kommuner.

    Idag saknas lagkrav på att inkludera målkonfliktsanalyser inom kommunal planering och miljöbedömning. Detta är troligen huvudanledning till att målkonflikter i nuläget lyfts fram i relativt liten grad i plandokumenten. Enligt resultaten från textanalysen tar 60 % av de granskade kommunerna upp målkonflikter någonstans i översiktsplanen eller den tillhörande miljökonsekvensbeskrivningen, men endast 11 % utför en strukturerad analys. Bristen på lagkrav kan också vara en anledning till att det i nuläget inte finns några övergripande strategier och verktyg att utgå ifrån som planerare, vilket har lett till enskilda kommuner har fått hitta sina egna lösningar.

    Att utgå ifrån kartor, respektive matriser, för att strukturerat kunna identifiera och analysera målkonflikter är metoder som använts i fallen med några av de intervjuade kommunerna. Sådana metoder kan hjälpa till att enkelt och strukturerat öka uppmärksamheten på de målkonflikter som kan uppstå i plandokumenten, samt att lyfta med dem till senare beslutssteg. Uppföljning av målkonflikterna till senare planeringssteg är dock utifrån intervjustudien i många fall oklar eller bristande. Att målkonflikterna följs upp är avgörande för att målkonfliktsanalysen ska ge någon positiv effekt på planeringen och inte förbli en skrivbordsprodukt. Att arbeta nära beslutsfattarna i en grupp bestående av personer med bred kompetens har identifierats som en framgångsfaktor för ett lyckat resultat där målkonflikterna har god chans att följas upp.

    I många fall handlar målkonflikter där man måste välja mellan ett mål eller ett annat i grund och botten om personliga värderingar och världsåskådningar. Målkonfliktshantering blir då i praktiken en fråga om diskussion och kompromisser. Att beslutsfattarna i dessa fall får väl informerade beslutsunderlag sammansatta utifrån bred kompetens kan då kraftigt öka möjligheten för att de bästa besluten tas för varje enskild situation.

  • Public defence: 2017-01-09 10:00 F3, Stockholm
    Beheshti, Reza
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Beheshti, Reza
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Sustainable Aluminum and Iron Production2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Aluminium recycling requires 95% less energy than primary production with no loss of quality. The Black Dross (BD) produced during secondary aluminium production contains high amounts of water-soluble compounds, therefore it is considered as a toxic waste. In the present work, salt removal from BD by thermal treatment has been investigated in laboratory scale. The optimum conditions for treatment were established, i.e., temperature, gas flow rate, holding time, rotation rate, and sample size. The overall degree of chloride removal was established to increase as a function of time and temperature. Even Pretreated Black Dross (PBD) was evaluated as a possible raw material for the production of a calcium aluminate-based ladle-fluxing agent to be used in the steel industry. The effects of different process parameters on the properties of the produced flux were experimentally investigated, i.e. CaO/Al2O3 ratio, temperature, holding time, and cooling media. The utilization of PBD as the alumina source during the production of a calcium aluminate fluxing agent shows promising results. The iron/steel industry is responsible for 9% of anthropogenic energy and process CO2 emissions. It is believed that the only way to a long-term reduction of the CO2 emissions from the iron/steel industry is commercialization of alternative processes such as Direct Reduction (DR) of iron oxide. Detailed knowledge of the kinetics of the reduction reactions is, however, a prerequisite for the design and optimization of the DR process. To obtain a better understanding of the reduction kinetics, a model was developed step-by-step, from a single pellet to a fixed bed with many pellets. The equations were solved using the commercial software COMSOL Multiphysics®. The final model considers the reaction rate and mass transfer inside the pellet, as well as the mass transfers and heat transfer in the fixed bed. All the models were verified against experimental results, and where found to describe the results in a satisfying way.

  • Public defence: 2016-12-20 10:00 B2, Stockhoolm
    Nabeel, Muhammad
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Nabeel, Muhammad
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    A study of micro-particles in the dust and melt at different stages of iron and steelmaking2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The dust particles generated due to mechanical wear of iron ore pellets and clusters formed in molten stainless steel alloyed with rare earth metals (REM) are considered in this study. Firstly, the influence of the characteristics of iron ore pellets, applied load on a pellet bed and partial reduction of the pellets on the size distribution of the generated dust was investigated. Secondly, REM clusters are investigated to evaluate the size distribution of the clusters. Also, an extreme value distribution (EVD) analysis has been applied for the observed REM clusters.

    The large sized pellets showed 10-20% higher wear rate than small sized pellets during wear in a planetary mill. Moreover, an increase of ~67% was observed in the friction and dust generation in the pellet bed as the applied load increased from 1 to 3 kg. Also, it was observed that a higher friction in the pellet bed can lead to an increased amount of airborne particles. The mechanical wear experiments of pellets reduced at 500 °C (P500) and 850 °C (P850) showed that P500 pellets exhibit ~16-35% higher wear rate than unreduced pellets. For the P850 pellets, the wear is inhibited by formation of a metallic layer at the outer surface of the pellets. The mechanism of dust generation has been explained using the obtained results.

    A reliable cluster size distribution of REM clusters was obtained by improving the observation method and it was used to explicate the formation and growth mechanism of REM clusters. The results show that the growth of clusters is governed by different types of collisions depending on the size of the clusters. For EVD analysis three different size parameters were considered. Moreover, using the maximum length of clusters results in a better correlation of EVD regression lines compared to other size parameters. Moreover, a comparison of predicted and observed maximum lengths of clusters showed that further work is required for the application of EVD analyses for REM clusters.

  • Pargman, Daniel
    et al.
    KTH, School of Computer Science and Communication (CSC), Media Technology and Interaction Design, MID. KTH, School of Computer Science and Communication (CSC), Centres, School of Architecture and the Built Environment (ABE), Centres, Centre for Sustainable Communications, CESC.
    Pargman, Daniel
    KTH, School of Computer Science and Communication (CSC), Media Technology and Interaction Design, MID. KTH, School of Computer Science and Communication (CSC), Centres, School of Architecture and the Built Environment (ABE), Centres, Centre for Sustainable Communications, CESC.
    Ahlsén, Edvard
    KTH, School of Computer Science and Communication (CSC), Media Technology and Interaction Design, MID.
    Engelbert, Cecilia
    KTH, School of Computer Science and Communication (CSC), Media Technology and Interaction Design, MID.
    Designing for sustainability: Breakthrough or suboptimisation?2016Conference paper (Refereed)
    Abstract [en]

    Technological developments in screen technologies pitches the thinner, brighter and energy-stingy OLED screen as a possible replacement for today’s television, computer and smartphone LCD screens. An OLED screen does not consume any energy at all when it displays the color black, but the potentially large energy savings can unfortunately evaporate and instead turn to losses when white is displayed. There is thus a mismatch between on the one hand the energy profiles of OLED screens and on the other hand user habits and current webpage design practices. This example thus raises important questions about system boundaries and about how to evaluate sustainable (or “sustainable”) technologies.

    We conducted a pilot study of user acceptance of alternative, OLED-adapted color schemes for webpages. We briefly discuss the results of the study, but primarily use it as a starting point for discussing the underlying questions of where, or indeed even if it makes sense to work towards realising the OLED screens’ potential for energy savings. Moving from LED to OLED screens is not only a matter of choosing between competing screen technologies, but would rather have implications for hardware and software design as well as for the practices of web designers, end users and content providers. 

  • Raghavan, Barath
    et al.
    ICSI.
    Raghavan, Barath
    ICSI.
    Pargman, Daniel
    KTH, School of Computer Science and Communication (CSC), Media Technology and Interaction Design, MID. KTH, School of Computer Science and Communication (CSC), Centres, School of Architecture and the Built Environment (ABE), Centres, Centre for Sustainable Communications, CESC.
    Refactoring Society: Systems Complexity in an Age of Limits2016Conference paper (Refereed)
    Abstract [en]

    Computing systems can be seen as the latest instance in a long chain of sociotechnical developments that have increased social complexity at an accelerated pace [4, 23, 24]. Today global in- dustrial society is particularly dependent upon and highly medi- ated by many computing systems. Over the past several decades, the growth of such systems have by and large been a boon as they have enabled a revolution in the way we communicate, work, and live. During this time, computer scientists in particular have con- tributed much to the development and spread of systems that have subtly, but unmistakably, transformed global society. Computing systems have also amplified sociotechnical complexity and accel- erated previous trends far more than prior technologies because of the inherent complexity of networked systems and the interlinking of previously independent systems [14]. 

  • Pargman, Daniel
    et al.
    KTH, School of Computer Science and Communication (CSC), Media Technology and Interaction Design, MID. KTH, School of Computer Science and Communication (CSC), Centres, School of Architecture and the Built Environment (ABE), Centres, Centre for Sustainable Communications, CESC.
    Pargman, Daniel
    KTH, School of Computer Science and Communication (CSC), Media Technology and Interaction Design, MID. KTH, School of Computer Science and Communication (CSC), Centres, School of Architecture and the Built Environment (ABE), Centres, Centre for Sustainable Communications, CESC.
    Eriksson, Elina
    KTH, School of Computer Science and Communication (CSC), Media Technology and Interaction Design, MID. KTH, School of Computer Science and Communication (CSC), Centres, School of Architecture and the Built Environment (ABE), Centres, Centre for Sustainable Communications, CESC.
    Friday, Adrian
    University of Lancaster.
    Limits to the Sharing Economy2016Conference paper (Refereed)
    Abstract [en]

    There has been much interest in the Sharing Economy in recent years, accompanied with the hope that it will change and specifically make better use of existing resources. It in- tuitively makes sense, from a sustainability point of view, that the sharing of resources is good. It could even be said that the Sharing Economy ought to align well with Comput- ing within Limits and its underlying premises. In this paper however, we take a critical stance and will elaborate on the intersection between the Sharing Economy and Limits (in- cluding pinpointing potential conflicts) so as to identify and discuss a ‘Limits-compliant Sharing Economy’. We argue that even though there are limits to the Sharing Economy today, it still has potential benefits for a future of scarcity— but only if the practice of sharing is approached with a dual focus on sharing and on limits at the same time. Finally we conclude that even though we have begun to explore the fu- ture of sharing, there is still a need to further develop ideas of how the underlying infrastructure for this movement will look. 

  • Public defence: 2016-12-16 13:15 Hörsal Q2, Stockholm
    Magnusson, Klas E. G.
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Magnusson, Klas E. G.
    KTH, School of Electrical Engineering (EES), Signal Processing.
    Segmentation and tracking of cells and particles in time-lapse microscopy2016Doctoral thesis, monograph (Other academic)
    Abstract [en]

    In biology, many different kinds of microscopy are used to study cells. There are many different kinds of transmission microscopy, where light is passed through the cells, that can be used without staining or other treatments that can harm the cells. There is also fluorescence microscopy, where fluorescent proteins or dyes are placed in the cells or in parts of the cells, so that they emit light of a specific wavelength when they are illuminated with light of a different wavelength. Many fluorescence microscopes can take images on many different depths in a sample and thereby build a three-dimensional image of the sample. Fluorescence microscopy can also be used to study particles, for example viruses, inside cells. Modern microscopes often have digital cameras or other equipment to take images or record time-lapse video.

    When biologists perform experiments on cells, they often record image sequences or sequences of three-dimensional volumes to see how the cells behave when they are subjected to different drugs, culture substrates, or other external factors. Previously, the analysis of recorded data has often been done manually, but that is very time-consuming and the results often become subjective and hard to reproduce. Therefore there is a great need for technology for automated analysis of image sequences with cells and particles inside cells. Such technology is needed especially in biological research and drug development. But the technology could also be used clinically, for example to tailor a cancer treatment to an individual patient by evaluating different treatments on cells from a biopsy.

    This thesis presents algorithms to find cells and particles in images, and to calculate tracks that show how they have moved during an experiment. We have developed a complete system that can find and track cells in all commonly used imaging modalities. We selected and extended a number of existing segmentation algorithms, and thereby created a complete tool to find cell outlines. To link the segmented objects into tracks, we developed a new track linking algorithm. The algorithm adds tracks one by one using dynamic programming, and has many advantages over prior algorithms. Among other things, it is fast, it calculates tracks which are optimal for the entire image sequence, and it can handle situations where multiple cells have been segmented incorrectly as one object. To make it possible to use information about the velocities of the objects in the linking, we developed a method where the positions of the objects are preprocessed using a filter before the linking is performed. This is important for tracking of some particles inside cells and for tracking of cell nuclei in some embryos.

     

     

     

    We have developed an open source software which contains all tools that are necessary to analyze image sequences with cells or particles. It has tools for segmentation and tracking of objects, optimization of settings, manual correction, and analysis of outlines and tracks. We developed the software together with biologists who used it in their research. The software has already been used for data analysis in a number of biology publications. Our system has also achieved outstanding performance in three international objective comparisons of systems for tracking of cells.

  • Public defence: 2016-12-16 10:15 D3, Stockholm
    Imani Jajarmi, Ramin
    KTH, School of Engineering Sciences (SCI), Mechanics, Fluid Physics.
    Imani Jajarmi, Ramin
    KTH, School of Engineering Sciences (SCI), Mechanics, Fluid Physics.
    Acoustic separation and electrostatic sampling of submicron particles suspended in air2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    We investigate experimentally the effects of acoustic forces on submicron aerosol in a channel flow. This technique can potentially overcome some of the limitations of conventional separation systems and provide advanced manipulation capabilities such as sorting according to size or density. The theoretical framework for acoustophoresis at such small length scales where molecular effects are expected to be significant is still incomplete and in need of experimental validation. The main objectives of this thesis are to identify the physical limitations and capabilities of acoustophoretic manipulation for submicron aerosol particles.

    Two sets of experiments were carried out: first, qualitative results revealed that acoustic manipulation is possible for submicron particles in air and that the acoustic force follows the trend expected by theoretical models developed for particles in inviscid fluids. The acoustic force on submicron particles was estimated in a second set of measurements performed with quantitative diagnostic tools. Comparison of these results with available theoretical models for the acoustic radiation forces demonstrates that for such small particles additional forces have to be considered. At submicron length scales, the magnitude of the forces observed is orders of magnitude higher than the predictions from the inviscid theory.

    One potential application for acoustophoresis is specifically investigated in this thesis: assist electrostatic precipitation (ESP) samplers to target very small aerosols, such as those carrying airborne viruses. To identify the shortcomings of ESP samplers that acoustophoresis should overcome, two ESP designs have been investigated to quantify capture efficiency as a function of the particle size and of the air velocity in a wind tunnel. The results reveal that both designs have limitations when it comes to sampling submicron aerosol particles. When exposed to polydispersed suspensions they behave as low-pass filters.

  • Public defence: 2016-12-16 10:00 FD5, Stockholm
    Hendil-Forssell, Peter
    KTH, School of Biotechnology (BIO), Industrial Biotechnology.
    Hendil-Forssell, Peter
    KTH, School of Biotechnology (BIO), Industrial Biotechnology.
    Rational engineering of esterases for improved amidase specificity in amide synthesis and hydrolysis2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Biocatalysis is an ever evolving field that uses enzymes or microorganisms for chemical synthesis. By utilizing enzymes that generally have evolved for specific reactions under mild conditions and temperatures, biocatalysis can be a more environmentally friendly option compared to traditional chemistry.

    Amide-type chemistries are important and bond formation avoiding poor atom economy is of high priority in organic chemistry. Biocatalysis could potentially be a solution but restricted substrate scope is a limitation. Esterases/lipases usually display broad substrate scope and catalytic promiscuity but are poor at hydrolyzing amides compared to amidases/proteases. The difference between the two enzyme classes is hypothesized to reside in one key hydrogen bond present in amidases, which facilitates the transition state for nitrogen inversion during catalysis.

    In this thesis the work has been focused on introducing a stabilizing hydrogen bond acceptor in esterases, mimicking that found in amidases, to develop better enzymatic catalysts for amide-based chemistries.

    By two strategies, side-chain or water interaction, variants were created in three esterases that displayed up to 210-times increased relative amidase specificity compared to the wild type. The best variant displayed reduced activation enthalpy corresponding to a weak hydrogen bond. The results show an estimated lower limit on how much the hydrogen bond can be worth to catalysis.

    MsAcT catalyze kinetically controlled N-acylations in water. An enzymatic one-pot one-step cascade was developed for the formation of amides from aldehydes in water that gave 97% conversion. In addition, engineered variants of MsAcT with increased substrate scope could synthesize an amide in water with 81% conversion, where the wild type gave no conversion. Moreover, variants of MsAcT displayed up to 32-fold change in specificity towards amide synthesis and a switch in reaction preference favoring amide over ester synthesis.

  • Public defence: 2016-12-16 10:30 K1, Stockholm
    Dinegdae, Yared H.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Dinegdae, Yared H.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Mechanics-based Design Framework for Flexible Pavements2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Load induced top-down fatigue cracking has been recognized recently as a major distress phenomenon in asphalt pavements. This paper presents a mechanics-based design framework in load and resistance factor design (LRFD) format for the top-down fatigue cracking performance evaluation of flexible pavements. This was achieved by enhancing further the hot mix asphalt fracture mechanics (HMA-FM) model through the incorporation of mixture morphology influence on key fracture properties, and incorporating partial safety factors to account for variabilities and uncertainties. The analysis framework was calibrated and validated using pavement sections that have high quality laboratory data and well documented field performance histories. Moreover, as traffic volume was identified in having a dominant influence on predicted performance, a further investigation was performed to establish and evaluate truck traffic characterization parameters effect on predicted results.

    A two-component reliability analysis methodology, which uses central composite design (CCD) based response surface approach for surrogate model generation and the first order reliability method (FORM) for reliability estimation was used for the development of the LRFD mechanics-based design framework. The effectiveness of the design framework was investigated through design examples, and the results have shown that the formulated partial safety factors have accounted effectively the variabilities involved in the design process. Further investigation was performed to establish the influence design inputs variabilities have on target reliabilities through case studies that combine input variabilities in a systematic way. It was observed from the results that the coefficient of variation (COV) level of the variability irrespective of the distribution type used have a significant influence on estimated target reliability.

  • Rizki, Kiki
    KTH, School of Electrical Engineering (EES).
    Rizki, Kiki
    KTH, School of Electrical Engineering (EES).
    Efficient Group Key Management for Internet of Things2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The Internet of Things has become the next big step of a general Internetevolution, and conveys the assurance of security as one of the biggest challenge.In particular, use cases and application scenarios that adopt groupcommunication schemes need to be properly secured, in order to protect themessage exchange among group members from a number of security attacks.A typical way to achieve secure group communication relies on the adoptionof a symmetric group key shared among all the group members. This in turnrequires to rely on a group key management scheme, which is responsible forrevoking and renewing the group key when nodes join or leave the group.Due to the resource-constrained nature of typical IoT devices, the adoptedgroup key management scheme should be ecient and highly scalable withthe group size.This thesis project has been conducted in collaboration with SICS SwedishICT, a research institute with focus on applied computer science. We haveimplemented an ecient group key management protocol initially proposedand designed by SICS, considering the Contiki operating system and resourceconstrainedIoT platforms. We have also experimentally evaluated the protocolin terms of storage overhead, communication overhead, energy consumptionand total required rekeying time.