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  • Public defence: 2017-12-14 10:00 D3, Stockholm
    Brynjell-Rahkola, Mattias
    KTH, School of Engineering Sciences (SCI), Mechanics, Stability, Transition and Control. KTH, Centres, SeRC - Swedish e-Science Research Centre. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Studies on instability and optimal forcing of incompressible flows2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis considers the hydrodynamic instability and optimal forcing of a number of incompressible flow cases. In the first part, the instabilities of three problems that are of great interest in energy and aerospace applications are studied, namely a Blasius boundary layer subject to localized wall-suction, a Falkner–Skan–Cooke boundary layer with a localized surface roughness, and a pair of helical vortices. The two boundary layer flows are studied through spectral element simulations and eigenvalue computations, which enable their long-term behavior as well as the mechanisms causing transition to be determined. The emergence of transition in these cases is found to originate from a linear flow instability, but whereas the onset of this instability in the Blasius flow can be associated with a localized region in the vicinity of the suction orifice, the instability in the Falkner–Skan–Cooke flow involves the entire flow field. Due to this difference, the results of the eigenvalue analysis in the former case are found to be robust with respect to numerical parameters and domain size, whereas the results in the latter case exhibit an extreme sensitivity that prevents domain independent critical parameters from being determined. The instability of the two helices is primarily addressed through experiments and analytic theory. It is shown that the well known pairing instability of neighboring vortex filaments is responsible for transition, and careful measurements enable growth rates of the instabilities to be obtained that are in close agreement with theoretical predictions. Using the experimental baseflow data, a successful attempt is subsequently also made to reproduce this experiment numerically.

    In the second part of the thesis, a novel method for computing the optimal forcing of a dynamical system is developed. The method is based on an application of the inverse power method preconditioned by the Laplace preconditioner to the direct and adjoint resolvent operators. The method is analyzed for the Ginzburg–Landau equation and afterwards the Navier–Stokes equations, where it is implemented in the spectral element method and validated on the two-dimensional lid-driven cavity flow and the flow around a cylinder.

  • Xuan, Wenxiang
    KTH, School of Chemical Science and Engineering (CHE).
    Glucose Levulinates as Bio-plasticizers2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Glucose, as the most plentiful sugar in nature, is a renewable resource and possesses excellent record in health safety. Levulinic acid is a platform chemical which plays an important role  in  biomass transformation and reactive intermediates. Both glucose and levulinic acid can be produced by biomass conversion with green processing techno logies.

    Due to the rising needs for bio-based, eco-friendly and non-toxic plasticizers, glucose levulinates as bio­ plasticizers were synthesized from glucose and levulinic acid, by utilizing microwave radiation or conventional condensation reaction (direct-heating method ). Acid number for the reaction liquor was measured by acid-base titration to follow the decrease of acid groups due to the reaction and the trend in  the acid number within reaction time displayed the process of esterification and possible sensitivity of the reaction rate to reaction scale. It showed that microwave radiation had superior ability in  enhancing reaction speed but it was also more sensitive to reaction scale and generated more diverse prod ucts  than the direct-heating method. Besides, the process of reaction and formation  of ester  bonds was  followed  and confirmed by FT IR.

    The achieved levulinate products were extracted by 2-pro panol and ethyl acetate. The practices showed several serio us problems in 2-propanol extraction, including high dosage required  for  NaCl and solvent and difficulties in purification. The ethyl acetate proved to be a suitable solvent for this study and the  extrac ted  product s  from  the Con-24hrs  and Micro-3/4/5/6/7hrs  were  characterized  by  1H  NMR,  13C N :tvlR. and LDI-MS. The results from spectrum suggested the presence of GL,. and G J .'l. type of levulinates. That means the glucose levulinates were  successfully  synthesized  although  the  dehydration side reaction of glucose was inevitable leading to the generation of glucosidic bonds. In addition, BG (mixture of glucose and glycosidic levulinates) was evaluated by so lution casting of starch and PVC. In order to minimize the microbial contaminations in solution casting of  starch, a  modified  method  was raised and applied. The results showed that 40% BG had goo d miscibility with starch and the conclusion was further proved by DSC measurements, while the BG performed poor miscibility with  PVC.

     

  • Johansson, Lisa
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology and Design.
    Nilsson, Anton
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology and Design.
    Arbetsmiljö ur Entreprenörens perspektiv: En utvärdering av den nuvarande situationen och förslag på utveckling2017Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The report compiles a survey of how different occupational groups at the building site are working with workplace environment at various IN3PRENÖR building sites. It shows that the difficulties in the workplace environment work are to communicate the goals and the way towards these goals. The difficulties are also in communicating shortcomings between the different occupational groups. The conclusion from the interviews and survey results is that the employees thrive in their workplace, disregarding weather it’s in the projects or the overall company.The construction industry is one of the most accidentally affected industries, and therefore is the workplace environment work extra important to minimize the risks of one of the workers being injured. The industry is regulated by the Work Environment Act and is the only profession mentioned specifically in the Act. In addition to the Work Environment Act, it is also regulated by different regulations. There are eighties, of which some twenty-thirty affect construction.The process of the result has consisted of site visits of seven of IN3PRENÖR's construction sites. The projects are varied, ranging from refurbishments and additions to schools to relocation of smoke ducts and tenant servants to government with EU standards instead of Swedish standards. These site visits included interviews, surveys and observations of the construction site. The work has then been compiled and analyzed to find out the shortcomings and how they can be improved.

  • Poormehdi Ghaemmaghami, Masoumeh
    KTH, School of Computer Science and Communication (CSC), Theoretical Computer Science, TCS.
    Tracking of Humans in Video Stream Using LSTM Recurrent Neural Network2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this master thesis, the problem of tracking humans in video streams by using Deep Learning is examined. We use spatially supervised recurrent convolutional neural networks for visual human tracking. In this method, the recurrent convolutional network uses both the history of locations and the visual features from the deep neural networks. This method is used for tracking, based on the detection results. We concatenate the location of detected bounding boxes with high-level visual features produced by convolutional networks and then predict the tracking bounding box for next frames. Because a video contain continuous frames, we decide to have a method which uses the information from history of frames to have a robust tracking in different visually challenging cases such as occlusion, motion blur, fast movement, etc. Long Short-Term Memory (LSTM) is a kind of recurrent convolutional neural network and useful for our purpose. Instead of using binary classification which is commonly used in deep learning based tracking methods, we use a regression for direct prediction of the tracking locations. Our purpose is to test our method on real videos which is recorded by head-mounted camera. So our test videos are very challenging and contain different cases of fast movements, motion blur, occlusions, etc. Considering the limitation of the training data-set which is spatially imbalanced, we have a problem for tracking the humans who are in the corners of the image but in other challenging cases, the proposed tracking method worked well.

  • Hedlund, Martin
    KTH, School of Computer Science and Communication (CSC).
    Detached Walk-in-Place2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Locomotion, the ability to walk freely in virtual environments, is a problem with no standardized solution. Walk-in-Place is one strand of solutions in which the user’s physical movement creates forward movement in the virtual environment. This technique is particularly useful for navigation in smartphone-based virtual reality without location detection. However, current mobile implementations use gaze-directed steering which limits the user’s ability to simultaneously scan the environment, which can reduce maneuverability. Additionally, step detection is triggered by head movement which shakes the head-mounted display and can therefore create discomfort and motion sickness. Detached Walk-in-place (dWIP) uses an external gyroscope attached to the body, or held in the hand, to track the user’s body rotation. This detaches the walking direction from gaze direction and removes step detection from the head-mounted-display. In this paper, I present a study of two different dWIP solutions (Torso- and Hand-directed). Both solutions are tested and compared with an existing mobile walk-in-place solution. Performance, user preference and simulator sickness were measured as the participants had to navigate a curved track using each method. The result shows that both dWIP methods required less steps compared with the current WIP, but the torso-directed dWIP is slower compared to the other two. There was no significant difference in user preference or simulator sickness. Overall, dWIP was well received and shows great potential as a mobile VR locomotion method.

  • Qiu, Yuchen
    KTH, School of Computer Science and Communication (CSC).
    Measuring the Differences Between Head and Gaze Orientation in Virtual Reality2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    With the spread of virtual reality, eye tracker embedded VR headset gradually becomes a trend. A company such as Fove has already released its eye-tracking VR headset. However, the relatively low frame rate of eye tracker in VR HMD (e.g. 90 fps) makes tracking unstable with consumption of computing power. Understanding relations between gaze direction and head direction would be helpful, for example, to predict and compensate eye tracking with head tracking. In this research, a unity project consisted of a moving object with variable parameters was created to examine if there’s correlation exists between players’ head direction and gaze direction in eye’s smooth pursuit movement. Furthermore, object parameters, shape, color, distance, speed and horizontal moving degree were tested to explore whether they can elicit statistically significant differences in gaze prediction. Results revealed that while smoothly pursuing a moving object with the gaze, people’s horizontal and vertical component of head direction and gaze direction are separately linearly correlated. Moreover, formulas were calculated via linear regression to express their relations. As for object parameters, significant impacts were detected for all five parameters and interaction effect of speed and horizontal moving degree with various effect size, partial eta squared.

  • Nyström, Sofie
    KTH, School of Computer Science and Communication (CSC), Media Technology and Interaction Design, MID.
    Providing meaningful waste feedback to larger grocery stores to promote sustainable development2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The role of the food retailer within sustainable consumption and production has been described as essential in the food production chain, with the possibility of affecting both producers and consumers to make greener choices. Logistic operations happening in the store are also important to ensure sustainable development, such as recycling. In the Swedish food retailer chain Coop, statistics on waste management in stores have been established recently, but are not communicated back to the stores. HCI have been used previously to provide environmental feedback, for example through persuasive technologies. This thesis set out to investigate how waste data can be presented to store managers and employees in a meaningful way, how this can contribute to sustainable development and provide motivation to improve the source sorting practice. Nine contextual interviews were conducted with a central facilities manager, store managers, employees and a representative from the waste collection company. Two mockups of web visualizations and two scenarios of interactive installations were designed and evaluated in two stores. Interviews highlighted the (lack of) knowledge, the economic compared to the environmental incentive for recycling and current feedback and comparisons. The design mockups were appreciated for the economic information and information provided, but scenarios being too interactive were discarded as too verbose. Resulting concepts are discussed in relation to interviews and evaluation feedback while emphasizing a holistic perspective on the practice of recycling. Using economic incentives through feedback to motivate sustainable development can facilitate recycling in stores for store managers, while other incentives may be used for employees. The potential use of environmental incentives should be further investigated. Mockups need further iterative development and more knowledge should be gathered on regular employees in future work.

  • Xu, Xueyan
    KTH, School of Chemical Science and Engineering (CHE).
    Development of Kraft Lignin and Coating Technique to Prepare Coated Urea Fertilisers with Increased Nutrient Use Efficiency2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Coating urea to prepare controlled release N-fertilizer has been considered as an effective way to increase its nutrient use efficiency, thus reduce its waste and the consequent harmful environmental impacts. Inorganic sulphur and synthetic polymers have been used in the industry as coating materials together with utilization of various types of expensive coating equipment which commonly requires also complicated technical setup and controls. As development trends, biopolymers are attention-grabbing to replace the synthetic polymers. Alternative simple coating technique is also desired. So far, polylactic acid (PLA) has been reported as a more promising biopolymer than several synthetic polymers for coating. On the other hand, highly purified industrial softwood kraft lignin (SKL) produced after LignoBoost process is now available in a large quantity, which should also be a promising biopolymer for the coating application. Aiming at increase of the efficiency of PLA-coated urea and development of alternative coating technique to generally make the preparation of control-released fertilizer more effective, economic and environmentally sustainable, in this study, SKL has been used in a PLA-SKL blending form as complex coating material and simple dip-coating technique has been investigated and applied.

    In order to lower the wettability of PLA-SKL coat layer, four different anhydrides, namely acetic anhydride, palmitic anhydride, lauric anhydride and trifluoroacetic anhydride, were used to esterify SKL to form AcSKL, PaSKL, LauSKL and TFASKL respectively before its utilization. NMR and FTIR analyses showed that the esterification reactions have been completed for AcSKL and PaSKL. LauSKL was partly esterified due to the low charge of lauric anhydride regent, while TFASKL was not esterified expectantly due to the steric hindrance between the three F atoms and polymeric SKL.

    In order to obtain organically bound nitrogen structure to also create slow-release type of N-fertilizer, Mannich reaction on SKL using diethylamine was also conducted to prepare ManSKL. The reaction was completed as shown by NMR and FTIR spectroscopy. To bring further functionality of metal chelation to open the possibility to also bring essential trace element into the final fertilizer, ethylenediaminetriacetic acid (ED3A) was synthesized and further used via Mannich reaction to modify SKL to form ED3ASKL. ED3A is not commercially available and it was synthesized successfully with an environmentally friendly method from commercial EDTA and the structure was verified by NMR spectroscopy. However, the Mannich reaction using ED3A was not very successful as shown by product’s NMR and FTIR spectra. In a comparison experiment using vanillyl alcohol as a lignin model structure, ED3A was successfully coupled onto the vanillyl alcohol structure as shown by NMR and FTIR spectra. Apparently there was a severe steric hindrance from SKL for the Mannich reaction using the larger molecule of ED3A than diethylamine for Mannich reaction.

    For utilization of dip-coating technique, dichloromethane(DCM) and tetrahydrofuran (THF) were chosen to dissolve PLA and SKL or the modified SKL respectively. Cast films of PLA/modified lignin complex were prepared using Teflon Petri-dishes. The optimal concentration of PLA in DCM and the effect of DCM/THF ratios on the prepared cast film which expectantly represents the quality of the complex coat in the coated urea were compared with SEM images and contact angle determination. It has been found that a 30 wt% of PLA in DCM was the best and this solution mixed with modified lignin solution (6 % in THF) in a ratio of DCM/THF =3/2 (v/v) had the best film performances and water barrier properties. Generally, the cast films from PLA/modified lignin complexes showed better properties compared with the neat PLA cast film. No pores and cracks were found on the surface. Comparatively, the LauSKL film showed the most homogeneous surface. But the AcSKL film had the best water barrier properties. The PLA/modified lignin complex coated urea was then prepared by dip-coating process. The coat thickness and weight increase showed statistically positive correlations against the repeating times of the dip-coating process. The coating layer also showed one single layer structure. The speed of urea releasing for coated urea was tested and the results showed that it was much slower than the un-coated or PLA-coated urea. The single-layered PLA/AcSKL and PLA/ManSKL were both observed with sound properties in delaying the release of urea cores in water.

    Conclusively, the PLA/modified SKL coated urea fertilizers prepared by dip-coating technique demonstrated in this study have highly efficiency with better effects of water barrier, organically N slow release, and nitrification inhibiting (due to free phenolic functional groups) properties. Both SKL and the dip-coating technique are promising in the fertilizer applications.

     

  • Kling, Alexander
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Integrated Product Development.
    Hur påverkas motivationen inom produktutveckling av virtuell interaktion?2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In today’s increasingly rapid-changing business environment, it is necessary for companies to be innovative,especially in the field of product development. One of the most acknowledge way for companies isto stay in business is to remain innovative, but in order to be innovative, creative employees is requiredand for them to endure that for a longer period of time, motivation is requires to execute a task. Motivationis thus an essential part of product development, while not only motivates employees but alsobenefits the company in terms of commitment, efficiency, increased margins from reduced staff turnoverand greater likelihood for more applications of talented recruits which been affected of positive and dedicatedemployees. The virtual interaction in the form of mail, instant messaging, social media, phonesand videoconferences etc. is a key feature for most businesses in today’s globalized market. Researchersfor all over the globe have thoroughly studied both motivation and virtual interaction and each coherenteffect, but we have not found any widespread hypothesis or studies made regarding the link betweenthem. As motivation is so central and virtual interaction so common it is thus interesting to investigatehow virtual communication in workspaces is used and if it has an influence on motivation. This reportpresents a bachelor thesis made at The Royal Institute of Technology during the spring semester of 2017with a primary purpose to investigate how and when virtual interaction is used in the workplace as well aspossible impact on motivation. The study has been conducted in two stages with an initial literature studyregarding the two fields followed by a qualitative empirical study of three established companies in theproduct development industry from which two respondents each been interviewed. The empirical materialhas then been analyzed using the theoretical framework from the literature, after which conclusionsbeen drawn. The work was partly performed by a workgroup of three people and partly individually. Theintroduction, theory and method was developed together after which each person was responsible for onecompany with two respondents form which the empirical data was analyzed and conclusions was drawn.The study shows small indications of what could have an affekt on motivation regarding certain forms ofvirtual interaction, such a higher degree of efficiency, creative thinking as well as increased number ofmisunderstandings, but some conclusion for a lager and more general trend could not be drawn.

  • Public defence: 2017-12-12 09:30 Kollegiesalen, Stockholm
    Wang, Wei
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatics. National University of Defense Technology, China.
    Spatially Adaptive Analysis and Segmentation of Polarimetric SAR Data2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In recent years, Polarimetric Synthetic Aperture Radar (PolSAR) has been one of the most important instruments for earth observation, and is increasingly used in various remote sensing applications. Statistical modelling and scattering analysis are two main ways for PolSAR data interpretation, and have been intensively investigated in the past two decades. Moreover, spatial analysis was applied in the analysis of PolSAR data and found to be beneficial to achieve more accurate interpretation results. This thesis focuses on extracting typical spatial information, i.e., edges and regions by exploring the statistical characteristics of PolSAR data. The existing spatial analysing methods are mainly based on the complex Wishart distribution, which well characterizes the inherent statistical features in homogeneous areas. However, the non-Gaussian models can give better representation of the PolSAR statistics, and therefore have the potential to improve the performance of spatial analysis, especially in heterogeneous areas. In addition, the traditional fixed-shape windows cannot accurately estimate the distribution parameter in some complicated areas, leading to the loss of the refined spatial details. Furthermore, many of the existing methods are not spatially adaptive so that the obtained results are promising in some areas whereas unsatisfactory in other areas. Therefore, this thesis is dedicated to extracting spatial information by applying the non-Gaussian statistical models and spatially adaptive strategies. The specific objectives of the thesis include: (1) to develop reliable edge detection method, (2) to develop spatially adaptive superpixel generation method, and (3) to investigate a new framework of region-based segmentation. Automatic edge detection plays a fundamental role in spatial analysis, whereas the performance of classical PolSAR edge detection methods is limited by the fixed-shape windows. Paper 1 investigates an enhanced edge detection method using the proposed directional span-driven adaptive (DSDA) window. The DSDA window has variable sizes and flexible shapes, and can overcome the limitation of fixed-shape windows by adaptively selecting homogeneous samples. The spherically invariant random vector (SIRV) product model is adopted to characterize the PolSAR data, and a span ratio is combined with the SIRV distance to highlight the dissimilarity measure. The experimental results demonstrated that the proposed method can detect not only the obvious edges, but also the tiny and inconspicuous edges in heterogeneous areas. Edge detection and region segmentation are two important aspects of spatial analysis. As to the region segmentation, paper 2 presents an adaptive PolSAR superpixel generation method based on the simple linear iterative clustering (SLIC) framework. In the k-means clustering procedure, multiple cues including polarimetric, spatial, and texture information are considered to measure the distance. Since the constant weighting factor which balances the spectral similarity and spatial proximity may cause over- or under-superpixel segmentation in different areas, the proposed method sets the factor adaptively based on the homogeneity analysis. Then, in heterogeneous areas, the spectral similarity is more significant than the spatial constraint, generating superpixels which better preserved local details and refined structures. Paper 3 investigates another PolSAR superpixel generation method, which is achieved from the global optimization aspect, using the entropy rate method. The distance between neighbouring pixels is calculated based on their corresponding DSDA regions. In addition, the SIRV distance and the Wishart distance are combined together. Therefore, the proposed method makes good use of the entropy rate framework, and also incorporates the merits of the SIRV distance and the Wishart distance. The superpixels are generated in a homogeneity-adaptive manner, resulting in smooth representation of the land covers in homogeneous areas, and well preserved details in heterogeneous areas.

  • Public defence: 2017-12-20 13:15 Kollegiesalen, Stockholm
    Wahlström, Johan
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Sensor Fusion for Smartphone-based Vehicle Telematics2017Doctoral thesis, monograph (Other academic)
    Abstract [en]

    The fields of navigation and motion inference have rapidly been transformed by advances in computing, connectivity, and sensor design. As a result, unprecedented amounts of data are today being collected by cheap and small navigation sensors residing in our surroundings. Often, these sensors will be embedded into personal mobile devices such as smartphones and tablets. To transform the collected data into valuable information, one must typically formulate and solve a statistical inference problem.

    This thesis is concerned with inference problems that arise when trying to use smartphone sensors to extract information on driving behavior and traffic conditions. One of the fundamental differences between smartphone-based driver behavior profiling and traditional analysis based on vehicle-fixed sensors is that the former is based on measurements from sensors that are mobile with respect to the vehicle. Thus, the utility of data from smartphone-embedded sensors is diminished by not knowing the relative orientation and position of the smartphone and the vehicle.

    The problem of estimating the relative smartphone-to-vehicle orientation is solved by extending the state-space model of a global navigation satellite system-aided inertial navigation system. Specifically, the state vector is augmented to include the relative orientation, and the measurement vector is augmented with pseudo observations describing well-known characteristics of car dynamics. To estimate the relative positions of multiple smartphones, we exploit the kinematic relation between the accelerometer measurements from different smartphones. The characteristics of the estimation problem are examined using the Cramér-Rao bound, and the positioning method is evaluated in a field study using concurrent measurements from seven smartphones.

    The characteristics of smartphone data vary with the smartphone's placement in the vehicle. To investigate this, a large set of vehicle trip segments are clustered based on measurements from smartphone-embedded sensors and vehicle-fixed accelerometers. The clusters are interpreted as representing the smartphone being rigidly mounted on a cradle, placed on the passenger seat, held by hand, etc. Finally, the problem of fusing speed measurements from the on-board diagnostics system and a global navigation satellite system receiver is considered. Estimators of the vehicle’s speed and the scale factor of the wheel speed sensors are derived under the assumptions of synchronous and asynchronous samples.

  • Public defence: 2017-12-15 09:00 M2, Stockholm
    Zhou, Xiamo
    KTH, School of Electrical Engineering (EES), Micro and Nanosystems.
    OSTE Microfluidic Technologies for Cell Encapsulation and Biomolecular Analysis2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In novel drug delivery system, the encapsulation of therapeutic cells in microparticles has great promises for the treatment of a range of health con- ditions. Therefore, the encapsulation material and technology are of great importance to the validity and efficiency of the advanced medical therapy. Several unsolved challenges in regards to versatile microparticle synthesis ma- terials and methods form the main obstacle for a translation of novel cell therapy concepts from research to clinical practice.

    Thiol-ene based polymer systems have emerged and gained great popular- ity in material development in general and in biomedical applications specif- ically. The thiol-ene platform is broad and therefore of interest for a variety of applications. At the same time, many aspects of this material platform are largely unexplored, for example material and manufacturing technology developments for microfluidic applications .

    In this Ph.D. thesis, thiol-ene materials are explored for use in cell encap- sulation. The marriage of these two technology fields breeds the possibility for a novel microfluidic cell encapsulation approach using a novel encapsulation material. To this end, several new manufacturing technologies for thiol-ene and thiol-ene-epoxy droplet microfluidic devices were developed. Moreover, core-shell microparticle synthesis for cell encapsulation based on a novel co- synthesis concept using a thiol-ene based material was developed and inves- tigated. Finally, a thiol-ene-epoxy system was also used for the formation of microwells and microchannels that improve protein analysis on microarrays.

    The first part of the thesis presents the background and state-of-the-art technologies in regards to cell therapy, microfluidics, and thiol-ene based ma- terials. In the second part of the thesis, a novel manufacturing approach of thiol-ene-epoxy material as well as core-shell particle co-synthesis in micro- fluidics using thiol-ene based material are presented and characterized. The third part of the thesis presents the cell viability studies of encapsulated cells using the novel encapsulation material and method. In the final part of the thesis, two applications of thiol-ene-epoxy gaskets for protein detection mi- croarrays are presented. 

  • Public defence: 2017-12-13 09:00 F3, Stockholm
    Fridström, Richard
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Resonant magnetic perturbation effect on the tearing mode dynamics: Novel measurements and modeling of magnetic fluctuation induced momentum transport in the reversed-field pinch2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The tearing mode (TM) is a resistive instability that can arise in magnetically confined plasmas. The TM can be driven unstable by the gradient of the plasma current. When the mode grows it destroys the magnetic field symmetry and reconnects the magnetic field in the form of a so-called magnetic island. The TMs are inherent to a type of device called the reversed-field pinch (RFP), which is a device for toroidal magnetic confinement of fusion plasmas. In the RFP, TMs arise at several resonant surfaces, i.e. where the field lines and the perturbation have the same pitch angle. These surfaces are closely spaced in the RFP and the neighboring TM islands can overlap. Due to the island overlap, the magnetic field lines become tangled resulting in a stochastic magnetic field, i.e. the field lines fill a volume instead of lying on toroidal surfaces. Consequently, a stochastic field results in an anomalously fast transport in the radial direction. Stochastic fields can also arise in other plasmas, for example, the tokamak edge when a resonant magnetic perturbation (RMP) is applied by external coils. This stochastization is intentional to mitigate the edge-localized modes. The RMPs are also used for control of other instabilities. Due to the finite number of RMP coils, however, the RMP fields can contain sidebands that decelerate and lock the TMs via electromagnetic torques. The locking causes an increased plasma-wall interaction. And in the tokamak, the TM locking can cause a plasma disruption which is disastrous for future high-energy devices like the ITER. In this thesis, the TM locking was studied in two RFPs (EXTRAP T2R and Madison Symmetric Torus) by applying RMPs. The experiments were compared with modern mode-locking theory. To determine the viscosity in different magnetic configurations where the field is stochastic, we perturbed the momentum via an RMP and an insertable biased electrode.

    In the TM locking experiments, we found qualitative agreement with the mode-locking theory. In the model, the kinematic viscosity was chosen to match the experimental locking instant. The model then predicts the braking curve, the short timescale dynamics, and the mode unlocking. To unlock a mode, the RMP amplitude had to decrease by a factor ten from the locking amplitude. These results show that mode-locking theory, including the relevant electromagnetic torques and the viscous plasma response, can explain the experimental features. The model required viscosity agreed with another independent estimation of the viscosity. This showed that the RMP technique can be utilized for estimations of the viscosity.

    In the momentum perturbation experiments, it was found that the viscosity increased 100-fold when the magnetic fluctuation amplitude increased 10-fold. Thus, the experimental viscosity exhibits the same scaling as predicted by transport in a stochastic magnetic field. The magnitude of the viscosity agreed with a model that assumes that transport occurs at the sound speed -- the first detailed test of this model. The result can, for example, lead to a clearer comparison between experiment and visco-resistive magnetohydrodynamics (MHD) modeling of plasmas with a stochastic magnetic field. These comparisons had been complicated due to the large uncertainty in the experimental viscosity. Now, the viscosity can be better constrained, improving the predictive capability of fusion science.

  • Public defence: 2017-12-12 10:00 B1, Stockholm
    Kellner, Hans
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Study of Non-metallic Inclusion in Alloy 8252017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    It is well known that inclusions affect the properties of steels and alloys. Therefore, it is important to understand what type of inclusions that exist and how they behave and especially with a focus on large size inclusions. Thus, the large size non-metallic inclusions in ferroalloy FeTi70R were investigated in two dimensions (2D) by using scanning electron microscopy (SEM) in combination with an energy dispersive technique (EDS). It was found that the FeTi70R ferroalloy contain complex oxide inclusions consisting mostly of CaO, SiO2 and TiOx. Furthermore, experimental trials were performed to investigate how these inclusions behaved when entering a melt. More specifically, a comparison between pure Fe and an Alloy 825 grade were made. These results determined the parameters effect on the transformation of the inclusions in the melt.

    The large size non-metallic inclusions in Alloy 825 during the ladle treatment were investigated during industrial trials by using both two dimensional (2D) and three dimensional (3D) microscopic investigations. The results showed that inclusions consisted of spherical oxides and clusters made up of oxides and nitrides. Further investigations found that the spherical inclusions were transformed from existing NMI in the FeTi70R ferroalloy and slag particles. As for the clusters, they originate from deoxidation products. Furthermore, small inclusions precipitated in the local zones around the added FeTi70R ferroalloy and titanium nitrides. Investigations also found that only Al2O3-MgO and TiN clusters exist after casting.

    Industrial trials were performed during the last period of the ladle treatment and using a combined electromagnetic (EMS) and gas (GS) stirring. The purpose to investigate the effect of different EMS directions on the agglomeration and on the removal of Al2O3-MgO and TiN clusters. The investigations were then performed in 3D after an electrolytic extraction of the metal samples. The results show that electromagnetic stirring in the upwards direction is best for the agglomeration of the Al2O3-MgO and TiN clusters. However, electromagnetic stirring in the downwards direction is more effective to remove clusters from the melt. This is in agreement with the theoretical predictions based on Stokes’, Brownian and Turbulent collisions. Also, the calculations showed that for Al2O3-MgO clusters with sizes <20 μm the Turbulent collision is the defining factor for agglomeration. However, both Stokes’ and Turbulent collisions are dominant for larger inclusions. For the TiN clusters, turbulent collisions is the dominant factor.

    Further investigations with more heats and stirring modes were done by using 2D microscopic investigations. More specifically, the number, size, composition and morphology of different inclusions were determined by using SEM in combination with EDS and Inca Feature analyses. The results show that the EMS in downwards direction with a 0.04 m3 min-1 gas flow rate promotes a general removal of Al2O3-MgO and TiN inclusions. Furthermore, that the upwards EMS direction promotes a drastically increase of inclusions having an equivalent size smaller than 11.2 μm. Moreover, the stirring with a 0.02 m3 min-1 gas flow rate has a better removal rate for both downwards and upwards stirring directions compared to the stirring with a 0.04 m3 min-1 gas flow rate. However, no influence on the inclusion composition and morphology could be seen from the different stirring modes.

  • Public defence: 2017-12-15 14:30 V3, Stockholm
    Boström, Erik
    KTH, School of Engineering Sciences (SCI), Mechanics, Stability, Transition and Control.
    Boundary Conditions for Spectral Simulations of Atmospheric Boundary Layers2017Licentiate thesis, monograph (Other academic)
    Abstract [en]

    An atmospheric boundary layer (ABL) is generally a very high Reynolds number boundary layer over a fully rough surface that is influenced by different external forces. Numerical simulations of ABLs are typically demanding, particularly due to the high Reynolds numbers. Large eddy simulation (LES) where the grid filtered Navier--Stokes equations are solved together with a turbulence model for the subgrid-scale motions is the most accurate and widely used technique to date for ABLs. However, high Reynolds numbers, filtered equations and rough surfaces do not support the simple no-slip boundary conditions together with a feasible grid resolution. A paramount part for the performance of an ABL LES simulation therefore lies in the quality of approximate wall boundary conditions, so called wall models.

         The vast majority of LES codes used for ABL simulations rely on spatial discretization methods with low order finite difference approximations for the derivatives in the inhomogeneous wall normal direction. Furthermore, the wall boundary conditions are typically chosen in a mesh-dependent, non-local way, relying on the finite differences formulation.

         In this thesis we focus on solving the ABL LES equations with a fully (pseudo) spectral Fourier--Chebyshev code. We present how wall boundary conditions can be formulated through Robin boundary conditions and how to implement these in the normal-velocity normal-vorticity formulation that we solve. A new idea of specifying boundary conditions directly in Fourier space where also the turbulence intensity statistics can be controlled is presented and verified. The present results show that the Robin-type formulation is effective at least in near-equilibrium boundary layers.

         The code and boundary conditions were tested in both low and high Reynolds number (open and full) channel flows of neutral and stable stratification. Results were validated with both low to moderate Reynolds number DNS statistics as well as with the logarithmic law. Our results indicate great potential for both the the new boundary condition formulation and the specific code implementation. Further analysis of more complex flow situations will show whether the Robin-type formulation will give similarly good results.

  • Public defence: 2017-12-18 14:00 D3, Stockholm
    Khoshkar, Sara
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Sustainability Assessment and Management.
    Paving the way for green qualities in urban development-Role of Environmental Assessment2017Licentiate thesis, monograph (Other academic)
    Abstract [en]

    Implementing urban development projects in planning practice while simultaneously providing sufficient green spaces has proven to be challenging. As a result, there is a growing need for practical approaches and tools for the integration of urban green qualities in the on-going densification of cities. Environmental assessment, as a proactive decision aiding tool, can hold an important role in integrating green qualities in urban development plans and projects. However, in recent years environmental assessment has only added moderate value to planning issues regarding green space. Therefore, this thesis was designed to contribute to the knowledge and understanding on the role environmental assessment can have in the integration of green qualities in future urban development plans and projects in efforts to aid practitioners. This aim was achieved through examination of existing urban green space planning practice in the Stockholm region (Paper I) and the practice of environmental assessment in a selection of European countries in relation to the following factors identified to be important for practice: timing, quality control, alternatives, monitoring and public participation (Paper II). The findings from both studies were then analysed to identify possibilities of green space planning within the framework of these factors. A qualitative research was employed for this study including: semi-structured interviews with municipal planners in the Stockholm region and environmental assessment experts for the European Commission, literature review, document analysis and case study analysis. The case studies analyzed in Paper I were located in municipalities of Haninge and Huddinge, suburban areas located to the south of Stockholm. In Paper II, the experts interviewed were environmental assessment experts from the European Commission from: Austria, Denmark, Finland, Greece, Luxembourg, the Netherlands, Norway and Slovenia. Through analysis of the results from both studies, the potential role of environmental assessment in integrating green qualities in urban development plans and projects are explored and discussed in relation to the factors. The potential of environmental assessment to enhance public participation and dialogues amongst actors, or bring forth green space issues within alternatives are a few of the roles discussed. Furthermore, a selection of pathways is suggested for the integration of green qualities in future urban development through the application of environmental assessment. For example, the implementation of developer dialogues in the environmental assessment process and the development of knowledge exchange platforms for sharing experiences in relation to green space planning and environmental assessment.

  • Fridström, Richard
    et al.
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Brunsell, Per
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Setiadi, Agung Chris
    Frassinetti, Lorenzo
    KTH, School of Electrical Engineering (EES), Fusion Plasma Physics.
    Multiple-harmonics RMP effect on tearing modes in EXTRAP T2R2017Conference paper (Other academic)
  • Public defence: 2017-12-12 10:00 F3, Stockholm
    Bogodorova, Tetiana
    KTH, School of Electrical Engineering (EES), Electric Power and Energy Systems.
    Modeling, Model Validation and Uncertainty Identification for Power System Analysis2017Doctoral thesis, monograph (Other academic)
    Abstract [en]

    It is widely accepted that correct system modeling and identification are among the most important issues power system operators face when managing instability and post-contingency scenarios. The latter is usually performed involving special computational tools that allow the operator to forecast, prevent system failure and take appropriate actions according to protocols for different contingency cases in the system. To ensure that operators make the correct simulation-based decisions, the power system models have to be validated continuously. This thesis investigates power system modeling, identification and validation problems that are formulated and based on data provided by operators, and offers new methods and deeper insight into stages of an identification cycle considering the specifics of power systems.

    One of the problems this thesis tackled is the selection of a modeling and simulation environment that provides transparency and possibility for unambiguous model exchange between system operators. Modelica as equation-based language fulfills these requirements. In this thesis Modelica phasor time domain models were developed and software-to-software validated against conventional simulation environments, i.e. SPS/Simulink and PSAT in MATLAB.

    Parameter estimation tasks for Modelica models require a modular and extensible toolbox. Thus, RaPiD Toolbox, a framework that provides system identification algorithms for Modelica models, was developed in MATLAB. Contributions of this thesis are an implementation of the Particle Filter algorithm and validation metrics for parameter identification. The performance of the proposed algorithm has been compared with Particle Swarm Optimization (PSO) algorithm when combined with simplex search and parallelized to get computational speed up. The Particle Filter outperformed PSO when estimating turbine-governor model parameters in the Greek power plant model relying on real measurements.

    This thesis also analyses different model structures (Nonlinear AutoRegressive eXogenous (NARX) model, Hammerstein-Wiener model, and high order transfer function) that are selected to reproduce nonlinear dynamics of a Static VAR Compensator (SVC) under incomplete information available for National Grid system operator. The study has shown that standard SVC model poorly reproduces the measured dynamics of the real system. Therefore, black-box mathematical modeling and identification approach has been proposed to solve the problem. Also, the introduced combination of first-principle and black-box approach has shown the best output fit. The methodology following identification cycle together with model order selection and model validation issues was presented in detail.

    Finally, one of the major contributions is a new method to formulate the uncertainty of parameters estimated in the form of a multimodal Gaussian mixture distribution that is estimated from the Particle Filter output by applying statistical methods to select the standard deviations. The proposed methodology gives additional insight into power system properties when estimating the parameters of the model. This allows power system analysts to decide on the design of validation tests for the chosen model.

  • Public defence: 2018-01-09 10:00 Kollegiesalen, Stockholm
    Nejad Ghafar, Ali
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    An Experimental Study to Measure Grout Penetrability, Improve the Grout Spread, and Evaluate the Real Time Grouting Control Theory2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Due to the significant influence of the grout penetrability properties on spread of grout in rock fractures, this study aimed to investigate the grout penetrability from four different aspects. In Part (a), after review of all the existing methodologies developed to measure the grout penetrability, Filter-pump and Penetrability-meter were examined against Short-slot to figure out which one is more reliable. The study decisively considered Short-slot more reliable. In part (b), the so-called varying aperture long slot (VALS), an artificial fracture with apertures of 230-10 μm, was developed to study the gout penetrability more realistically. In part (c), a low-frequency rectangular pressure impulse was introduced to improve the grout spread by successive erosion of the produced filter cakes in consecutive cycles. The results showed considerable improvement in experiments using Short-slot. The dissipation of the pressure impulses was then investigated using VALS with noticeable remaining amplitudes after 2.0-2.7 m. In part (d), VALS was once more introduced to examine RTGC theory in a fracture with variable aperture. The study showed a relatively satisfactory agreement between the experimental results and the predictions of the grout propagation using the hydraulic aperture, whereas the predictions using the mean physical aperture showed considerably faster spread.

  • Bernving, Niels
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Numerical thermal analysis of SEAM2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis is on the topic of numerical thermal analysis, specically of the SmallExplorer for Advanced Missions SEAM. SEAM is a 3 unit Cubesat, which isgoing to be launched in a sun-synchronous orbit to measure the magnetic sphere.It makes use of a boom deployment system to remove the sensors from themagnetic eld inuences of the body. The goal of this thesis is to study thethermal behaviour of the satellite, specically the internal components and thethermal deformation of the boom structure. The numerical simulations makeuse of the Monte Carlo Ray-tracing method. Furthermore thermal vacuumcycle tests have been compared to the thermal model as a form of validation.Additionally the thesis also serves as a nal thermal analysis of the satellite, tocheck if all components operate within their specied thermal operating range.

  • Henriksson, Patrick
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Strategic Sustainability Studies.
    Comparative Life Cycle Assessment of Sludge Treatment Systems: Is recycling aluminium based coagulant from chemical sludge the way of the future?2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Chemical coagulation is a widely used wastewater treatment method around the world to reduce impurities from the process water in various industries. However, the large amounts of coagulation chemicals that are required for the removal of dissolved particles create a chemical sludge which poses a great environmental problem. Purac AB, a Swedish wastewater treatment company attempts to solve this problem with a new technology called the ReAl process. The ReAl process can recycle the aluminium ions from the commonly used coagulant aluminium sulfate, which reduces the amount of chemical sludge and the amount of aluminium sulfate needed in the coagulation process. In this study, a comparative life cycle assessment was conducted with a cradle-to-grave approach and mostly in accordance with the ISO-14040 series with the only deviation of not including resource-based impact categories. The goal was to evaluate the environmental impact of two sludge treatment systems – a conventional system (system 1) and a system which includes the ReAl process (system 2). Furthermore, the environmental performance of two dewatering equipment’s, a decanter centrifuge and a filter press, were examined in system 1, while in system 2, the exclusion of sludge drying was investigated.

    The scope of the study did not include the infrastructure of the sludge treatment systems and the ReAl process since previous studies have shown that, the environmental impact from the infrastructure in the wastewater treatment industry is relatively small compared to other factors, such as the energy and coagulation chemical used in these systems.

    The characterization results showed that system 2 had the lowest environmental impact on all the evaluated impact categories. The results also revealed that system 1 would have a slightly lower environmental impact if the chemical sludge was dewatered with a decanter centrifuge instead of a filter press. Similarly, system 2 would have a slightly lower environmental impact if sludge drying was excluded from the system. However, the environmental performance gain from selecting the best dewatering and drying equipment is limited and considered within the margin of error. Thus, this thesis suggests selecting the sludge treatment equipment based on their economic and technical factors before their environmental performance.

    The largest environmental impact in system 1 derived from the use of the coagulation chemical aluminium sulfate, while in system 2, sulfuric acid used in the ReAl process contributed the most to its environmental impact. The sensitivity analysis showed that a “clean” electricity mix is essential for system 2 and the ReAl process overall impact on the environment compared to system 1.

  • Public defence: 2017-12-13 15:15 D3, Stockholm
    Negi, Prabal
    KTH, School of Engineering Sciences (SCI), Mechanics, Stability, Transition and Control. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, Centres, SeRC - Swedish e-Science Research Centre.
    Boundary layers over wing sections2017Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The understanding of developing boundary layers over wings is an important topic from the perspective of industrial applications. An increased understanding would be consequential not only for achieving higher fuel efficiency but also in the design of aircraft control strategies. With these aims in mind, the current work aims to further the understanding of developing boundary layer over wingsections. The study is performed with two particular perspectives in mind -unsteady aerodynamic effects in a pitching airfoil and turbulent boundary layerstructure in non-equilibrium boundary layers over a stationary airfoil.The boundary layer evolution in unsteady natural laminar flow airfoils undergoing small-amplitude pitch-oscillations is investigated. For high Reynolds numbers the origins of the non-linear unsteady aerodynamic response of laminar airfoils is explained on the basis of quasi-steady assumptions. Temporal nonlinearitiesin aerodynamic forces are shown to be inherently linked to thenon-linearities of static aerodynamic force coefficients and that a simple phaselagconcept can model the observed non-linear unsteady response. On the other hand at lower Reynolds numbers, when there exists an unstable leading edgelaminar separation bubble, the unsteady response is dynamically rich and changes in boundary layer characteristics can be abrupt. Such quasi-steadyphase-lag concepts are no longer appropriate to explain the unsteady flow physics in such a case. For the case of stationary airfoils, flow statistics for flow around an airfoil at two different Reynolds numbers are compared to assess Reynolds number effects in non-equilibrium flows. Pressure gradient effects found to be stronger at low Reynolds numbers, leading to higher energy in the larger structures present  in the outer part of the turbulent boundary layer.

  • Public defence: 2017-12-11 13:00 Kollegiesalen, Stockholm
    Kolitsidas, Christos
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering. Electromagnetic Engineering.
    Next Generation Wideband Antenna Arrays for Communications and Radio Astrophysics2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Wideband, wide-scan antenna arrays are a promising candidate for the future wireless networks and as well as an essential part of experimental radio astrophysics. Understanding the underline physics of the element performance in the array environment is paramount to develop and improve the performance of array systems. The focus of this thesis is to develop novel wideband antenna array technologies and develop new theoretical insights of the fundamental limits of antenna arrays. The developed methodologies have also been extended to include a radio astrophysics application for the global 21cm experiment.  

    Investigating the fundamental antenna array limits and extracting general performance measures can provide a priori estimates for any application of arrays. In this thesis, a general measure for antenna arrays, the array figure of merit is proposed. This measure couples bandwidth, height from the ground plane and reflection coefficient in a bounded quantity. An extension of the array figure of merit that is able to provide matching, bandwidth and directivity/gain limits is also introduced.

    The soft Vivaldi array is introduced as a novel wideband, wide-scan angle array technology. Periodic structure loading has been utilized to improve the array's performance and mold the electromagnetic wave behavior to our benefit. The soft condition has been utilized in the same manner as the conventional soft-horn antenna at the Vivaldi element. An integrated matching layer in the form of periodic strip loading is introduced. A single polarized soft Vivaldi array prototype has been developed fabricated and measured. The developed finite array has been loaded with a soft condition in the periphery to mitigate edge effects. The results indicated improved cross-polarization and side-lobe levels.

    A new class of wideband antenna arrays, the Strongly Coupled Asymmetric Dipole Array (SCADA) was also proposed in this thesis. Exploiting asymmetry in the array element introduces an additional degree of freedom that improves bandwidth and scanning performance. A novel methodology for terminating finite arrays is also proposed. The theory and an experimental antenna array is presented with good agreement between measured and simulated results. An effort to integrate a vertical wide angle matching layer was also addressed and a prototype array with this concept is presented.

    In the last part of this thesis, a methodology for the detection of the global cosmological 21cm signal from the Epoch of Reionization (EoR) is developed. The main sources of errors in this experiment, the foregrounds and the antenna chromaticity are evaluated. A new algorithmic methodology for extracting the global EoR signal is proposed. The method is based on piecewise polynomial fitting and has successfully been applied and evaluated. An antenna array that is based on the methodologies described in this thesis has been developed and evaluated with the proposed algorithm.

  • Public defence: 2017-12-15 09:00 Sal-C, Kista.
    Awan, Ahsan Javed
    KTH, School of Information and Communication Technology (ICT), Software and Computer systems, SCS.
    Performance Characterization and Optimization of In-Memory Data Analytics on a Scale-up Server2017Doctoral thesis, monograph (Other academic)
    Abstract [en]

    The sheer increase in the volume of data over the last decade has triggered research in cluster computing frameworks that enable web enterprises to extract big insights from big data. While Apache Spark defines the state of the art in big data analytics platforms for (i) exploiting data-flow and in-memory computing and (ii) for exhibiting superior scale-out performance on the commodity machines, little effort has been devoted to understanding the performance of in-memory data analytics with Spark on modern scale-up servers. This thesis characterizes the performance of in-memory data analytics with Spark on scale-up servers.Through empirical evaluation of representative benchmark workloads on a dual socket server, we have found that in-memory data analytics with Spark exhibit poor multi-core scalability beyond 12 cores due to thread level load imbalance and work-time inflation (the additional CPU time spent by threads in a multi-threaded computation beyond the CPU time required to perform the same work in a sequential computation). We have also found that workloads are bound by the latency of frequent data accesses to the memory. By enlarging input data size, application performance degrades significantly due to the substantial increase in wait time during I/O operations and garbage collection, despite 10% better instruction retirement rate (due to lower L1cache misses and higher core utilization).For data accesses, we have found that simultaneous multi-threading is effective in hiding the data latencies. We have also observed that (i) data locality on NUMA nodes can improve the performance by 10% on average,(ii) disabling next-line L1-D prefetchers can reduce the execution time by upto14%. For garbage collection impact, we match memory behavior with the garbage collector to improve the performance of applications between 1.6xto 3x and recommend using multiple small Spark executors that can provide up to 36% reduction in execution time over single large executor. Based on the characteristics of workloads, the thesis envisions near-memory and near storage hardware acceleration to improve the single-node performance of scale-out frameworks like Apache Spark. Using modeling techniques, it estimates the speed-up of 4x for Apache Spark on scale-up servers augmented with near-data accelerators.

  • Public defence: 2017-12-11 10:00 F3, Stockholm
    Almas, Muhammad Shoaib
    KTH, School of Electrical Engineering (EES), Electric Power and Energy Systems.
    Synchrophasor Applications and their Vulnerability to Time Synchronization Impairment2017Doctoral thesis, monograph (Other academic)
    Abstract [en]

    Recent years have seen the significance of utilizing time-synchronized, high resolution measurements from phasor measurement units (PMUs) to develop and implement wide-area monitoring, protection and control (WAMPAC) systems. WAMPAC systems aim to provide holistic view of the power system and enable detection and control of certain power system phenomena to enhance reliability and integrity of the grid.

    This thesis focuses on the design, development and experimental validation of WAMPAC applications, and investigates their vulnerability to time synchronization impairment. To this purpose, a state-of-the-art real-time hardware-in-the-loop (RT-HIL) test-bench was established for prototyping of synchrophasor-based applications. This platform was extensively used throughout the thesis for end-to-end testing of the proposed WAMPAC applications. To facilitate the development of WAMPAC applications, an open-source real-time data mediator is presented that parses the incoming synchrophasor stream and provides access to raw data in LabVIEW environment.

    Within the domain of wide-area protection applications, the thesis proposes hybrid synchrophasor and IEC 61850-8-1 GOOSE-based islanding detection and automatic synchronization schemes. These applications utilize synchrophasor measurements to assess the state of the power system and initiate protection / corrective action using GOOSE messages. The associated communication latencies incurred due to the utilization of synchrophasors and GOOSE messages are also determined. It is shown that such applications can have a seamless and cost-effective deployment in the field.

      Within the context of wide-area control applications, this thesis explores the possibility of utilizing synchrophasor-based damping signals in a commercial excitation control system (ECS). For this purpose, a hardware prototype of wide-area damping controller (WADC) is presented together with its interface with ECS. The WADC allows real-time monitoring and remote parameter tuning that could potentially facilitate system operators’ to exploit existing damping assets (e.g. conventional generators) when changes in operating conditions or network topology emerges.

    Finally the thesis experimentally investigates the impact of time synchronization impairment on WAMPAC applications by designing RT-HIL experiments for time synchronization signal loss and time synchronization spoofing. It is experimentally demonstrated that GPS-based time synchronization impairment results in corrupt phase angle computations by PMUs, and the impact this has on associated WAMPAC application. 

  • Bello, Bernardo
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    PROCESS MANUFACTURING SELECTION MODEL2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • Stellwag, Brigitte
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Factory Planning – The Creation and Evaluation of Material Flow- oriented Layouts2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • Bai, Mo
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Parampalli Mahabaleshwar, Sagar
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Accelerated Engine Suspension Load Prediction and Exhaust System Displacement Simulation2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • Hallberg, Daniel
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Ringdahl, Patrik
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Study on a high precision drilling tool with focus on power source and driveline2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • Sjöberg, Isabelle
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Energioptimering av värmesystem för biogasproduktion av matavfall2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • Baid, Vishal
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Integrated Product Development.
    Seres, Irén
    KTH, School of Industrial Engineering and Management (ITM).
    Tjänstedesign för hållbar interntransport: Design av hållbara interntransportlösningar för anställda på ett svenskt bilindustriföretag2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • Janson, Amelie
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Integrated Product Development.
    Lindqvist, Caroline
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Integrated Product Development.
    Working in a Highly Automated Truck - Who, What and Why?2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • Risberg, Erik
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Integrated Product Development.
    Large companies taking climate action by using science-based methods: A case study performed at a global leader in appliance manufacturing with a leading position in sustainability2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • Mata Yandiola, Cristina
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Feasibility Analysis of the Use of Hybrid Solar PV-Wind Power Systems for Grid Integrated Mini-grids in India2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • Mahesh, Bhargav
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Umer, Muhammad
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Smart Connected Power Tools: An Industrial Implementation of Event Driven Architecture2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • Public defence: 2017-12-08 10:00 B2, Stockholm
    Xu, Xin
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Physical Metallurgy. KTH.
    Phase Separation in Stainless Steels Studied by Small-angle Neutron Scattering2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Fe-Cr based steels, i.e. stainless steels, possessing a combination of excellent corrosion resistance and good mechanical properties, have indispensable applications ranging from low-end cooking utensils, to sophisticated components for nuclear power plants. However, the bcc/bct phase containing stainless steels which have a miscibility gap (MG) suffer from the so-called “475 oC embrittlement” leading to hardness increase and toughness deterioration. It occurs due to demixing of Fe and Cr leading to the formation of Fe-rich (α) and Cr-rich (α′) regions in bcc/bct phases. The demixing is referred to as phase separation (PS).

    The goal of this work was to study PS in ferrite containing stainless steels mainly by small-angle neutron scattering (SANS). Firstly, the application of different experimental techniques for the study of phase separation in Fe-Cr based steels was reviewed and supplemented by new measurements. SANS was shown to be very sensitive to the nanostructure change caused by PS and capable of characterizing the early stages of PS in Fe-Cr alloys. However, atom probe tomography and transmission electron microscopy are complementary to SANS. Therefore, in order to have a more complete view of the microstructure, the combination of these techniques should be pursued. Secondly, the factors affecting the initial microstructure prior to aging treatment and the effect of the resulted initial microstructure on PS were systematically investigated using binary Fe-Cr model alloys. The critical temperature of the MG was determined to be located between 560 and 580 oC in binary Fe-Cr. The results indicate that the solution treatment temperature above the MG and the cooling rate after solution treatment have significant effects on the initial microstructure and thus on PS during subsequent aging. The mechanisms responsible for the changed aging behavior are Cr clustering, quenched-in vacancy and decomposition during cooling. Therefore, computational simulations should take into account these factors and the initial microstructure to make predictions that are more accurate. Thirdly, the study was extended to PS in commercial duplex stainless steels (DSSs) which are of practical importance in various industries, e.g., nuclear power. It is found that alloying elements have an important effect on PS in DSSs. The grade 2507 (25 %Cr, 7 %Ni) experiences stronger PS than grade 2205 (22 %Cr, 5 % Ni) for the same heat treatment. Moreover, the fracture mechanisms as well as the mechanical properties depend on the extent of PS.  Finally, the fundamental aspects regarding the neutron scattering behavior for Fe-Cr alloys were examined. The results show that the nuclear and magnetic scattering of neutrons depend on the evolution of the nanoscale compositional fluctuation in Fe-Cr alloys. The ratio of the magnitude of nuclear scattering versus magnetic scattering varies with the extent of PS.

  • Shah, Bilal
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Distributed biogas production for biogas fuel2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • Al-Khoury, Fadi
    KTH, School of Industrial Engineering and Management (ITM).
    Safety of Machine Learning Systems in Autonomous Driving2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • Karanwal, Anup
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Implementation of Simulation Techniques for Supply Chain Risk Management in Process Industry2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • Barragán, Camila
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy and Climate Studies, ECS.
    Reducing emissions in the Mexican power sector: Economic and political feasibility analysis of policy mechanisms2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • Eugenio Cantú Gómez, David
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Abrasiv nötning av ythärdade jordbearbetningsverktyg2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • Erni, David
    et al.
    KTH, School of Industrial Engineering and Management (ITM).
    Öhman, Jenny
    KTH, School of Industrial Engineering and Management (ITM).
    Utveckling av pillerdosa för underlättande av självmedicinering2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • Norin, Isabelle
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Industrial Ecology.
    Vilken avfallstaxa skapar högst avfallskvalitet?: En jämförelse av SÖRAB-regionens avfallstaxor och tjänster som styrmedel för hushållens avfallshantering2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The waste fee is an instrument that can be used by the municipality in order to achieve what has been decided in the municipality’s waste management plan, and reflects the municipality’s ambitions and objectives regarding waste management. It can be designed in multiple ways, comprised with a fixed fee and/or a fee depending on e.g. size of the waste bin and collection frequency. The municipality has a possibility to design the waste fee in order to encourage a more environmentally beneficial behaviour among the residents, however the waste fee has to fulfill the principle of cost-based pricing and equal cost for a comparable service. The aim of this study is to investigate how the different designs of a waste fee by municipalities in the SÖRAB-region, through economic incentives and regulations, impact the quality of the waste from households. The study investigates the amount of household waste, number of households enrolled in the food waste collection scheme and the share of the total amount of food waste generated by a household that is separately collected. Further the study investigates the amount of hazardous waste and electrical and electronical equipment waste that  yearly arise from households, and the share of this amount that is improperly disposed of with the household waste. The study also examines whether the results may be affected by other factors than the waste fee. The results are based on an earlier conducted waste composition study combined with statistics on collected amounts of waste, interviews with authorities regarding waste management in each municipality, the waste management plans of each municipality, and a literature study.

    Households in the two municipalities that apply a weight-based fee do not create lower amounts of household waste than households in other municipalities, which contradict a majority of the findings from the literature study. In several of the municipalities where a weekly-based collection of waste is most frequent it would, based on the amount of waste, be possible to change to a less frequent collection scheme. This therefore indicates that the current economic incentive to motivate this kind of change is not sufficient. It could also be discussed whether this lack of incentive for a frequency change has a negative impact on the amount of waste generated by the household. There is a link, although rather weak, between municipalities where a bi-weekly collection is most common and a lower amount of household waste.

    The highest percentage of households enrolled in the food waste collection scheme for single-family houses (SFH) is found in Sundbyberg (100 %), where it is mandatory for the households to separate their food waste. Upplands Väsby has the lowest percentage for SFH (23 %), where the yearly fee for a household that enrolls in food waste collection increases marginally. The yearly difference in cost for SFH among the municipalities ranges from a decrease of 1 455 SEK (-42.3 %), to an increase  of 5 SEK (+0.3 %) when a household joins the food waste collection scheme. The results indicate that there is no correlation between a large percentage decrease of the yearly cost and a higher percentage of households enrolled. The marginally increased yearly fee in Upplands Väsby however seems to negatively impact the percentage of enrolled households. The lack of correlation withholds for both SFH and multi-family dwellings (MFD). On a general level the waste fee is relatively low compared to other expenses for a household, which in combination with the fact that households generally according to the interviews lack awareness of the waste fee and waste management plan, could be factors that explain the lack of a correlation. The highest percentage of households enrolled for MFD is found in Sollentuna (90 %), while the lowest is in Vallentuna (22 %). The food waste collection scheme has been in progress for at least 15 years longer in Sollentuna than in the other municipalities, which could have had an impact on the results. The yearly economic incentive for each household in an MDF is lower than for SFH and the decrease of the fee when enrolling in food waste collection varies between 387 SEK and 142 SEK. The decrease of the fee for an MDF calculated as a percentage ranges from -30.6 % to -10.8 % between the municipalities.

    The share of food waste that is separately sorted by a household differs between the municipalities and ranges from approximately 31 % to 55 %. It is not possible to distinguish the share for SFH and MFD separately, which might have an impact on the differences that occur between municipalities since the municipality with a high share of households in MFD represents the lowest share of separately sorted food waste. It is, according to some of the interviews, often more difficult to reach out to households in MFD with information. The results of this calculation surprisingly show that the municipality in which the participation of a household in a SFH leads to a marginally increased yearly fee, does not show a higher share of food waste being separately sorted. Calculations based on share of food waste separately collected per capita results in a range from 16 % to 41 %, implying that municipalities in the lower range are relatively far off from the regional as well as the national objective.

    The cost-free services for collection of hazardous waste and electrical and electronical equipment waste offered to SFH are not used to a large extent, which could possibly depend on poor knowledge regarding the services, or that these households bring these kinds of waste to the recycling centers themselves. A larger amount of hazardous waste is improperly disposed of with the household waste in MFD than in SFH in five of the nine municipalities. This can be compared to electrical and electronical equipment waste, where a larger amount is improperly disposed of in MFD in one municipality. The amount of hazardous waste and of electrical and electronical equipment waste disposed of per capita is lowest in municipalities with the highest share of households living in MFD. The shares of these two waste fractions that are improperly disposed of are at the same time highest in these municipalities, indicating either a possible source of error due to the calculations or that the household type impacts the disposal patterns.

    The results show a slight correlation between larger amounts of hazardous waste being improperly disposed of with the household waste in MFD compared to households in SFH, in the municipalities that do not offer a cost-free collection service for this type of waste for MFD. This correlation does not appear for electrical and electronical equipment waste. It is however questionable whether this result is due to the lack of the cost-free collection services, since it does not seem to be used to a large extent. The municipalities where residents are offered additional collection systems beyond access to the recycling center and to the mobile recycling center seem to be ranked slightly higher than the other municipalities examined, regarding lower amounts of hazardous waste disposed of with household waste. There is no such correlation visible for electrical and electronical equipment waste.

    It is, due to the low number of municipalities examined, not possible to draw statistically significant conclusions from the results of the study. Furthermore there is a potential source of error in the  method used, since amounts of different types of waste presented and discussed are based on a  waste composition study where the results may be impacted by randomness. It is difficult to present recommendations regarding how to optimally design the waste fee, since the results in this study  do not seem to show any strong correlations between a particular design and successful results.  The lack of correlations is possibly due to the interaction of different aspects in a municipality’s work, making it difficult to pinpoint a single specifically effective factor.

  • Runhem, Lovisa
    KTH, School of Computer Science and Communication (CSC).
    Resource efficient travel mode recognition2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this report we attempt to provide insights to how a resource efficient solution for transportation mode recognition can be implemented on a smartphone using the accelerometer and magnetometer as sensors for data collection. The proposed system uses a hierarchical classification process where instances are first classified as vehicles or non-vehicles, then as wheel or rail vehicles, and lastly as belonging to one of the transportation modes: bus, car, motorcycle, subway, or train. A virtual gyroscope is implemented as a low-power source of simulated gyroscope data. Features are extracted from the accelerometer, magnetometer and virtual gyroscope readings that are sampled at 30 Hz, before they are classified using machine learning algorithms from the WEKA machine learning library.

    An Android application was developed to classify real-time data, and the resource consumption of the application was measured using the Trepn profiler application. The proposed system achieves an overall accuracy of 82.7% and a vehicular accuracy of 84.9% using a 5 second window with 75% overlap while having an average power consumption of 8.5 mW. 

  • Kalogiras, Vasileios
    KTH, School of Computer Science and Communication (CSC).
    Sentiment Classification with Deep Neural Networks2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Sentiment analysis is a subfield of natural language processing (NLP) that attempts to analyze the sentiment of written text.It is is a complex problem that entails different challenges. For this reason, it has been studied extensively. In the past years traditional machine learning algorithms or handcrafted methodologies used to provide state of the art results. However, the recent deep learning renaissance shifted interest towards end to end deep learning models. On the one hand this resulted into more powerful models but on the other hand clear mathematical reasoning or intuition behind distinct models is still lacking. As a result, in this thesis, an attempt to shed some light on recently proposed deep learning architectures for sentiment classification is made.A study of their differences is performed as well as provide empirical results on how changes in the structure or capacity of a model can affect its accuracy and the way it represents and ''comprehends'' sentences.

  • Ristic, Richard
    KTH, School of Industrial Engineering and Management (ITM).
    A High Heat Flux Facility Design forTesting of Methane in Rocket NozzleCooling Channels2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • Ridard, Mathilde
    KTH, School of Industrial Engineering and Management (ITM).
    NUMERICAL STUDY OF TWO-PHASE FLOWS FOR PERFORMANCES IN SOLID ROCKET PROPULSION2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • Ekqvist, Caroline
    KTH, School of Industrial Engineering and Management (ITM).
    A feasibility study of running a small-scale water purification unit with base station waste heat2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • Arvidsson, Daniel
    KTH, School of Architecture and the Built Environment (ABE), Real Estate and Construction Management.
    Green Bonds – A beneficial financing form?2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Title: Green bonds – A beneficial financing form? Purpose: The purpose of this master thesis was to examine housing companies reasoning behind issuing green bonds for financing their projects. What advantages and disadvantages that are currently connected to green bonds and if the green bond market can motivate companies to build more sustainable.  Methodology: This thesis is built upon a literature review and a quantitative study, where the data was collected through a questionnaire sent out to various housing companies on the Swedish real estate market.  Findings: Weather or not green bonds is a beneficial financing for seems to be individual for each company. Companies with more ambitious sustainability goals seems to be more likely to issue green bonds. The positives with issuing green bonds is that the company is able to reach out to new investors and that the gain positive attention from important stakeholders. The current downsides with the financing form is that the issuing costs are currently higher for green bonds than conventional bonds and many companies still believe that they are not getting enough compensations for the higher costs. With this in regard it is not very likely that the green bond market can be a motivation for actors to build more sustainable. Today there are actors that do have both the financial capability and the projects needed to enter the market, that still chooses not to. Therefore, it is hard to believe that the green bond market in its current state will drive green investments that wouldn’t have been financed in any other way. 

  • Hallberg, Daniel
    et al.
    KTH, School of Industrial Engineering and Management (ITM).
    Ringdahl, Patrik
    KTH, School of Industrial Engineering and Management (ITM).
    Study on a high precision drilling tool with focus on power source and driveline2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis