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  • 2251.
    Aghaali, Habib
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Internal Combustion Engines.
    Ångström, Hans-Erik
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Internal Combustion Engines.
    Turbocharged SI-Engine Simulation with Cold and Hot-Measured Turbocharger Performance Maps2012In: Proceedings of ASME Turbo Expo 2012, Vol 5, ASME Press, 2012, p. 671-679Conference paper (Refereed)
    Abstract [en]

    Heat transfer within the turbocharger is an issue in engine simulation based on zero and one-dimensional gas dynamics. Turbocharged engine simulation is often done without taking into account the heat transfer in the turbocharger. In the simulation, using multipliers is the common way of adjusting turbocharger speed and parameters downstream of the compressor and upstream of the turbine. However, they do not represent the physical reality. The multipliers change the maps and need often to be different for different load points. The aim of this paper is to simulate a turbocharged engine and also consider heat transfer in the turbocharger. To be able to consider heat transfer in the turbine and compressor, heat is transferred from the turbine volute and into the compressor scroll. Additionally, the engine simulation was done by using two different turbocharger performance maps of a turbocharger measured under cold and hot conditions. The turbine inlet temperatures were 100 and 600°C, respectively. The turbocharged engine experiment was performed on a water-oil-cooled turbocharger (closed waste-gate), which was installed on a 2-liter gasoline direct-injected engine with variable valve timing, for different load points of the engine. In the work described in this paper, the difference between cold and hot-measured turbocharger performance maps is discussed and the quantified heat transfers from the turbine and to/from the compressor are interpreted and related to the maps.

  • 2252.
    Aghaali, Habib
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Internal Combustion Engines. KTH, School of Industrial Engineering and Management (ITM), Centres, Competence Center for Gas Exchange (CCGEx).
    Ångström, Hans-Erik
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Internal Combustion Engines. KTH, School of Industrial Engineering and Management (ITM), Centres, Competence Center for Gas Exchange (CCGEx).
    Serrano, Jose R
    Universitat Politècnica de València.
    Evaluation of different heat transfer conditions on an automotive turbocharger2014In: International Journal of Engine Research, ISSN 1468-0874, E-ISSN 2041-3149, Vol. 16, no 2, p. 137-151Article in journal (Refereed)
    Abstract [en]

    This paper presents a combination of theoretical and experimental investigations for determining the main heat fluxes within a turbocharger. These investigations consider several engine speeds and loads as well as different methods of conduction, convection, and radiation heat transfer on the turbocharger. A one-dimensional heat transfer model of the turbocharger has been developed in combination with simulation of a turbocharged engine that includes the heat transfer of the turbocharger. Both the heat transfer model and the simulation were validated against experimental measurements. Various methods were compared for calculating heat transfer from the external surfaces of the turbocharger, and one new method was suggested.

    The effects of different heat transfer conditions were studied on the heat fluxes of the turbocharger using experimental techniques. The different heat transfer conditions on the turbocharger created dissimilar temperature gradients across the turbocharger. The results show that changing the convection heat transfer condition around the turbocharger affects the heat fluxes more noticeably than changing the radiation and conduction heat transfer conditions. Moreover, the internal heat transfers from the turbine to the bearing housing and from the bearing housing to the compressor are significant, but there is an order of magnitude difference between these heat transfer rates.

  • 2253.
    Aghaei Meibodi, Mania
    KTH, School of Architecture and the Built Environment (ABE), Architecture, Architectural Technologies.
    Generative Design Exploration: Computation and Material Practice2016Doctoral thesis, monograph (Other academic)
    Abstract [en]

    Today, computation serves as an important intermediary agent for the integration of analyses and the constraints of materialisation into design processes. Research efforts in the field have emphasised digital continuity and conformity between different aspects of a building project. Such an approach can limit the potential for significant discoveries, because the expression of architectural form is reduced to the varying tones of one fabrication technique and simulation at a time. This dissertation argues that disparate sets of digital and physical models are needed to incorporate multiple constraints into the exploration, and that the way the designer links them to one another significantly impacts the potential for arriving at significant discoveries. Discoveries are made in the moment of bridging between models, representational mediums, and affiliated processes.

    This dissertation examines the capacity of algorithm—as a basis for computation—to diversify and expand the design exploration by enabling the designer to link disparate models and different representational mediums. It is developed around a series of design experiments that question how computation and digital fabrication can be used to diversify design ideation, foster significant discoveries, and at the same time increase flexibility for the designer’s operation in the design process. The experiments reveal the interdependence of the mediums of design—algorithm, geometry, and material—and the designer’s mode of operation. They show that each medium provides the designer with a particular way of incorporating constraints into the exploration. From the way the designer treats these mediums and the design process, two types of exploration are identified: goal oriented and open-ended. In the former, the exploration model is shaped by the designer’s objective to reach a specified goal through the selection of mediums, models, and tools. In the latter, the design process itself informs the designer’s intention. From the kinds of interdependencies that are created between mediums in each experiment, three main exploration models emerge: circular and uniform, branched and incremental, and parallel and bidirectional.

    Finally, this dissertation argues that the theoretical case for integral computational design and fabrication must be revised to go beyond merely applying established computational processes to encompass the designer and several design mediums. The new model of design exploration is a cooperation between algorithm, geometry, materials, tools, and the designer. For the exploration to be novel, the designer must play a significant role by choosing one medium over another when formulating the design problem and establishing design drivers from the set of constraints, by linking the design mediums, by translating between design representations, and by describing the key aspects of the exploration in terms of algorithms.

     

  • 2254.
    Aghaiemeybodi, Hamia
    KTH, School of Architecture and the Built Environment (ABE), Architecture.
    Digital Design & AlterationThe Establishment of Socio-technological Hub2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The establishment of a Socio-technological Hub is through refurbishing, altering and reprogramming of already existing KTH School of architecture, Stockholm by the means of digital tools. This project is driven with two parallel objectives. First, exploring the potential for alteration when using the contemporary digital tools in the design and production. Seconded exploring the potential of architecture as a medium for integration of the knowledge in 3 sectors of society: university, industry and public.

  • 2255. Aghajani, A.
    et al.
    Razani, Abdolrahman
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.), Mathematics (Div.). Department of Mathematics, Faculty of Science, Imam Khomeini International University, Iran .
    Some completeness theorems in the Menger probabilistic metric space2008In: Applied Sciences: APPS, ISSN 1454-5101, E-ISSN 1454-5101, Vol. 10, p. 1-8Article in journal (Refereed)
    Abstract [en]

    In this article, some new completeness theorems in probabilistic normed space are proved. Moreover, the existence of a constrictive Monger probabilistic normed space is shown.

  • 2256.
    Aghakhanian Fereydani, Behrooz
    KTH, School of Electrical Engineering (EES), Communication Networks.
    Secure Vehicular Communication Systems: Cross-Domain VPKI, Design and Implementation2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Enabling communication among vehicles on the road has advantages, but it also introduces a number of security drawbacks. A Vehicular PKI (VPKI) provides an infrastructure that brings security and privacy within the VPKI domain. But when it comes to establishing a trust model among multiple VPKI domains, a new trust model is needed in order to facilitate travelling across domains. This project proposes an approach and partially implements a scalable and efficient Cross-Domain VPKI trust model that, first, enables VPKI domains to establish different levels of trust with each other and, second, it suggests that a Domain CA (DCA) in each domain to evaluate trustworthiness of vehicle’s Long Term Certificate (LTC). As result, CAs in VPKI domains will have more granular control over issuing pseudonym Foreign Certificates for a vehicle that travels into their domain.

  • 2257.
    Aghasi, Keivan
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.), Entrepreneurship and innovation.
    Predicting who stays or leaves after the acquisition:: Target’s top manager turnover2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In acquisition of high-tech and knowledge intensive firms, scholars have paid special attention to top managers’ status after the deal. Literature suggests that these managers in particular CEOs if kept in post-acquisition provide coordination capacity for the acquirer to transfer the knowledge and technology from the target to the acquirer while minimizing the disruptive effect of post-acquisition integration process. In addition, the acquirer benefits from human capital embedded in target’s managerial resources; especially in high-tech and knowledge intensive firms where top managers are founders or patent holders. Although the above mentioned argument have been validated by empirical studies showing that top manager’s turnover reduces the post-acquisition performance for the acquirers, multiple empirical studies have reported abnormal managerial turnover shortly after the acquisition. This thesis made an attempt to explain this puzzling phenomenon by investigating on the determinants of the top manager’s turnover of the target in the post-acquisition period. The study finds that in case of CEOs, acquirers do not rely always on coordinating capacity provided by them in post-acquisition. Indeed, the acquirer’s choice of provision of coordination is beyond the target’s CEO retention. The choice of coordination depends on the existing level of coordination capacities and the acquisition’s motivation. In addition, founder-CEOs are more likely to stay after the acquisition because of their valuable firm-specific human capital for the acquirer. However, this value diminishes by the maturity of the target. In addition, similarity in demographic characteristics of the two CEOs (of the acquirer and target) causes social attraction, collaboration and cooperation which ultimately increases the chance that the target’s CEO retention. Finally, diversity within the target’s top management team (TMT) directly increases their chance of departure after the deal. The diversity engenders social frictions, conflicts and coordination inefficiencies.

  • 2258.
    Aghasi, Keivan
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.), Entrepreneurship and innovation.
    Similarity as an antecedentfor target’s CEO turnover: Do birds of a feather flocktogether?Manuscript (preprint) (Other academic)
    Abstract [en]

    This paper investigates on behavioral aspects of managerial turnover in post-acquisition period. In particular, the paper aims to determine to what extent demographic similarity between CEOs improves their (intergroup) relations which ultimately causes target’s CEO retention in post-acquisition. The paper found that similarity in demographic characteristics of CEOs increases the probability of announcing the retention of target’s CEO after the deal is closed. Additionally, similarity increases the probability of misjudgment in determining target’s CEO status in post-acquisition period. Finally, the paper found that experience as the acquirer’s capability reduces the effect of similarity. This results is based on acquisition of small high-tech firms between 2001 and 2005.

  • 2259.
    Aghasi, Keivan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.), Entrepreneurship and innovation.
    Brown, Terrence
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.), Entrepreneurship and innovation.
    Rossi-Lamastra, Cristina
    Department of Management, Economics and Industrial Engineering, Politecnico di Milano.
    The role of top managers in M&A: Reviewing thirty years of literature and setting directions for future researchManuscript (preprint) (Other academic)
    Abstract [en]

    The present paper reviews the literature on the role of top management teams (TMT) in mergers and acquisitions (M&A). Given variety of theoretical lenses applied in this field - such as agency theory or upper echelon – and the plethora of on-going empirical studies in the last three decades, we believe this literature review has a crucial value for the existing strand of studies and future studies to come. In particular, it systematizes the extant knowledge by documenting the contradictory results of prior empirical studies, making argument on the sources of these contradictions, and pointing out future directions of research.

  • 2260.
    Aghasi, Keivan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.), Entrepreneurship and innovation.
    Colombo, Massimo
    Department of Management, Economics and Industrial Engineering, Politecnico di Milano.
    Rossi-Lamastra, Cristina
    Department of Management, Economics and Industrial Engineering, Politecnico di Milano.
    Antecedents of target CEO departure in post-acquisitions: The leading role of founderManuscript (preprint) (Other academic)
    Abstract [en]

    This study investigates on firm specific human capital of target CEOs in small high-tech firms as the antecedent of their retention after the acquisition. The main finding of the paper is that acquirers are willing to keep the founder-CEOs because of their valuable embedded human capital. This value is to the extent that founder-CEOs compare to professional CEOs have a higher chance of retention when relatedness between acquirer and target is high or when the acquirer structurally integrates the target after the acquisition; the two conditions that general managerial skills and industry specific skills of the CEOs are not of interest for the acquirers. Also the value of firm specific human capital depends on the maturity of the target. The value diminishes as the target is more mature at the time of acquisition. This research is based on empirical analysis of acquisition of small high-tech firms between 2001 and 2005.

  • 2261.
    Aghasi, Keivan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.), Entrepreneurship and innovation.
    Colombo, Massimo
    Department of Management, Economics and Industrial Engineering, Politecnico di Milano.
    Rossi-Lamastra, Cristina
    Department of Management, Economics and Industrial Engineering, Politecnico di Milano.
    Post-acquisition implementation of small high-tech firms: Looking beyond the surfaceManuscript (preprint) (Other academic)
    Abstract [en]

    In post-acquisition, the main challenge for the acquirer is choosing the right coordination mechanism with respect to the required level of coordination and associated costs of implementation of the mechanism. In acquisition of small high-tech firms, the challenge is exacerbated as technology and knowledge transfer requires high level of coordination while the costs related such as loss of autonomy and organizational disruptions are also higher. In this paper, we showed that acquirer’s choice of coordination mechanisms is determined by the cost-benefit trade-off. In particular, we found that, component technology as a form of task interdependency necessitates higher level of coordination and justifies choosing mechanisms to provide high level of coordination at higher cost. On the contrary, technological relatedness and prior alliance between acquirer and target provide coordination capacity, which in turn reduce the benefits of choosing mechanisms to provide high level of coordination with respect to the associated costs. This study is based on empirical analysis of 403 acquisitions of small high-tech firms between 2001 and 2005. 

  • 2262.
    Aghasi, Keivan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.), Entrepreneurship and innovation.
    Lougui, Monia
    Broström, Anders
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.), Entrepreneurship and innovation.
    Colombo, Massimo
    Department of Management, Economics and Industrial Engineering, Politecnico di Milano.
    Why diverse top managementteams break up in post-acquisition periodsManuscript (preprint) (Other academic)
    Abstract [en]

    This paper proposes a complementary explanation behind the turnover of target’s top managers in post-acquisition periods. Although human capital and acquisition implementation literature describe managerial retention as desirable, empirical studies have reported significant managerial turnover in acquisition of high-tech and knowledge intensive firms. Borrowing some insights from the team diversity literature, the paper examines the ex-ante diversity among top managers of knowledge-intensive and high-tech firms as an antecedent of their turnover in post-acquisition. We argue that diversity reduces the coordination efficiency necessary to transfer knowledge and facilitate post-acquisition organizational integration, and managers belonging to such teams are more likely to be replaced. Empirical analysis drawing on 2164 top managers in 297 Swedish firms shows that managerial position diversity as a separation, pay disparity and industrial tenure diversity as a variety indeed are associated with managerial exit in three years after the acquisition.

  • 2263.
    Aghasi, Keivan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.), Economics. Politecnico di Milano.
    Lougui, Monia
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.), Economics.
    Broström, Anders
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.), Economics.
    Colombo, Massiomo
    Why Diverse Top Management Teams Break up in Post-acquisition Periods2015Conference paper (Other academic)
    Abstract [en]

    This paper proposes a complementary explanation behind the turnover of target’s top managers in post-acquisition periods. Although human capital and acquisition implementation literature describe managerial retention as desirable, empirical studies have reported significant managerial turnover in acquisition of high-tech and knowledge intensive firms. Borrowing some insights from the team diversity literature, the paper examines the ex-ante diversity among top managers of knowledge-intensive and high-tech firms as an antecedent of their turnover in post-acquisition. We argue that diversity reduces the coordination efficiency necessary to transfer knowledge and facilitate post-acquisition organizational integration, and managers belonging to such teams are more likely to be replaced. Empirical analysis drawing on 2164 top managers in 297 Swedish firms shows that managerial position diversity as a separation, pay disparity and industrial tenure diversity as a variety indeed are associated with managerial exit in three years after the acquisition.

  • 2264.
    Aghasibeig, Maniya
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Fredriksson, Hasse
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Laser cladding of a featureless iron-based alloy2012In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 209, p. 32-37Article in journal (Refereed)
    Abstract [en]

    Laser cladding experiments with powder injection technique were carried out to create coatings of Fe-8.1Cr6.4Mn-5.3Si-6.9Mo-3.6C alloy on AISI 1018 steel substrates using a diode laser. Analysis of the clad layers showed that an almost featureless structure was formed at different dilutions between 1% and 4%. The featureless phase with a high hardness of 1155 HV was characterized as a metastable solid solution of e phase. However, the featureless structure appeared to be very brittle with numerous cracks. After heat-treatment, it decomposed into a bainitic structure with a high hardness of 884 HV.

  • 2265.
    Aghazadeh, Omid
    KTH, School of Computer Science and Communication (CSC), Computer Vision and Active Perception, CVAP.
    Data Driven Visual Recognition2014Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis is mostly about supervised visual recognition problems. Based on a general definition of categories, the contents are divided into two parts: one which models categories and one which is not category based. We are interested in data driven solutions for both kinds of problems.

    In the category-free part, we study novelty detection in temporal and spatial domains as a category-free recognition problem. Using data driven models, we demonstrate that based on a few reference exemplars, our methods are able to detect novelties in ego-motions of people, and changes in the static environments surrounding them.

    In the category level part, we study object recognition. We consider both object category classification and localization, and propose scalable data driven approaches for both problems. A mixture of parametric classifiers, initialized with a sophisticated clustering of the training data, is demonstrated to adapt to the data better than various baselines such as the same model initialized with less subtly designed procedures. A nonparametric large margin classifier is introduced and demonstrated to have a multitude of advantages in comparison to its competitors: better training and testing time costs, the ability to make use of indefinite/invariant and deformable similarity measures, and adaptive complexity are the main features of the proposed model.

    We also propose a rather realistic model of recognition problems, which quantifies the interplay between representations, classifiers, and recognition performances. Based on data-describing measures which are aggregates of pairwise similarities of the training data, our model characterizes and describes the distributions of training exemplars. The measures are shown to capture many aspects of the difficulty of categorization problems and correlate significantly to the observed recognition performances. Utilizing these measures, the model predicts the performance of particular classifiers on distributions similar to the training data. These predictions, when compared to the test performance of the classifiers on the test sets, are reasonably accurate.

    We discuss various aspects of visual recognition problems: what is the interplay between representations and classification tasks, how can different models better adapt to the training data, etc. We describe and analyze the aforementioned methods that are designed to tackle different visual recognition problems, but share one common characteristic: being data driven.

  • 2266.
    Aghazadeh, Omid
    KTH, School of Computer Science and Communication (CSC).
    Object Segmentation using Spatial and Spatio-Temporal Features.2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 2267.
    Aghazadeh, Omid
    et al.
    KTH, School of Computer Science and Communication (CSC), Computer Vision and Active Perception, CVAP.
    Azizpour, Hossein
    KTH, School of Computer Science and Communication (CSC), Computer Vision and Active Perception, CVAP.
    Sullivan, Josephine
    KTH, School of Computer Science and Communication (CSC), Computer Vision and Active Perception, CVAP.
    Carlsson, Stefan
    KTH, School of Computer Science and Communication (CSC), Computer Vision and Active Perception, CVAP.
    Mixture component identification and learning for visual recognition2012In: Computer Vision – ECCV 2012: 12th European Conference on Computer Vision, Florence, Italy, October 7-13, 2012, Proceedings, Part VI, Springer, 2012, p. 115-128Conference paper (Refereed)
    Abstract [en]

    The non-linear decision boundary between object and background classes - due to large intra-class variations - needs to be modelled by any classifier wishing to achieve good results. While a mixture of linear classifiers is capable of modelling this non-linearity, learning this mixture from weakly annotated data is non-trivial and is the paper's focus. Our approach is to identify the modes in the distribution of our positive examples by clustering, and to utilize this clustering in a latent SVM formulation to learn the mixture model. The clustering relies on a robust measure of visual similarity which suppresses uninformative clutter by using a novel representation based on the exemplar SVM. This subtle clustering of the data leads to learning better mixture models, as is demonstrated via extensive evaluations on Pascal VOC 2007. The final classifier, using a HOG representation of the global image patch, achieves performance comparable to the state-of-the-art while being more efficient at detection time.

  • 2268.
    Aghazadeh, Omid
    et al.
    KTH, School of Computer Science and Communication (CSC), Computer Vision and Active Perception, CVAP.
    Carlsson, Stefan
    KTH, School of Computer Science and Communication (CSC), Computer Vision and Active Perception, CVAP.
    Large Scale, Large Margin Classification using Indefinite Similarity MeasurensManuscript (preprint) (Other academic)
  • 2269.
    Aghazadeh, Omid
    et al.
    KTH, School of Computer Science and Communication (CSC), Computer Vision and Active Perception, CVAP.
    Carlsson, Stefan
    KTH, School of Computer Science and Communication (CSC), Computer Vision and Active Perception, CVAP.
    Properties of Datasets Predict the Performance of Classifiers2013In: BMVC 2013 - Electronic Proceedings of the British Machine Vision Conference 2013, British Machine Vision Association, BMVA , 2013Conference paper (Refereed)
    Abstract [en]

    It has been shown that the performance of classifiers depends not only on the number of training samples, but also on the quality of the training set [10, 12]. The purpose of this paper is to 1) provide quantitative measures that determine the quality of the training set and 2) provide the relation between the test performance and the proposed measures. The measures are derived from pairwise affinities between training exemplars of the positive class and they have a generative nature. We show that the performance of the state of the art methods, on the test set, can be reasonably predicted based on the values of the proposed measures on the training set. These measures open up a wide range of applications to the recognition community enabling us to analyze the behavior of the learning algorithms w.r.t the properties of the training data. This will in turn enable us to devise rules for the automatic selection of training data that maximize the quantified quality of the training set and thereby improve recognition performance.

  • 2270.
    Aghazadeh, Omid
    et al.
    KTH, School of Computer Science and Communication (CSC), Computer Vision and Active Perception, CVAP.
    Carlsson, Stefan
    KTH, School of Computer Science and Communication (CSC), Computer Vision and Active Perception, CVAP.
    Properties of Datasets Predict the Performance of Classifiers2013Manuscript (preprint) (Other academic)
  • 2271.
    Aghazadeh, Omid
    et al.
    KTH, School of Computer Science and Communication (CSC), Computer Vision and Active Perception, CVAP.
    Sullivan, Josephine
    KTH, School of Computer Science and Communication (CSC), Computer Vision and Active Perception, CVAP.
    Carlsson, Stefan
    KTH, School of Computer Science and Communication (CSC), Computer Vision and Active Perception, CVAP.
    Multi view registration for novelty/background separation2012In: Computer Vision and Pattern Recognition (CVPR), 2012 IEEE Conference on, IEEE Computer Society, 2012, p. 757-764Conference paper (Refereed)
    Abstract [en]

    We propose a system for the automatic segmentation of novelties from the background in scenarios where multiple images of the same environment are available e.g. obtained by wearable visual cameras. Our method finds the pixels in a query image corresponding to the underlying background environment by comparing it to reference images of the same scene. This is achieved despite the fact that all the images may have different viewpoints, significantly different illumination conditions and contain different objects cars, people, bicycles, etc. occluding the background. We estimate the probability of each pixel, in the query image, belonging to the background by computing its appearance inconsistency to the multiple reference images. We then, produce multiple segmentations of the query image using an iterated graph cuts algorithm, initializing from these estimated probabilities and consecutively combine these segmentations to come up with a final segmentation of the background. Detection of the background in turn highlights the novel pixels. We demonstrate the effectiveness of our approach on a challenging outdoors data set.

  • 2272.
    Aghazadeh, Omid
    et al.
    KTH, School of Computer Science and Communication (CSC), Computer Vision and Active Perception, CVAP.
    Sullivan, Josephine
    KTH, School of Computer Science and Communication (CSC), Computer Vision and Active Perception, CVAP.
    Carlsson, Stefan
    KTH, School of Computer Science and Communication (CSC), Computer Vision and Active Perception, CVAP.
    Novelty Detection from an Ego-Centric perspective2011In: Proceedings of the IEEE Computer Society Conference on Computer Vision and Pattern Recognition, 2011, p. 3297-3304Conference paper (Refereed)
    Abstract [en]

    This paper demonstrates a system for the automatic extraction of novelty in images captured from a small video camera attached to a subject's chest, replicating his visual perspective, while performing activities which are repeated daily. Novelty is detected when a (sub)sequence cannot be registered to previously stored sequences captured while performing the same daily activity. Sequence registration is performed by measuring appearance and geometric similarity of individual frames and exploiting the invariant temporal order of the activity. Experimental results demonstrate that this is a robust way to detect novelties induced by variations in the wearer's ego-motion such as stopping and talking to a person. This is an essentially new and generic way of automatically extracting information of interest to the camera wearer and can be used as input to a system for life logging or memory support.

  • 2273. Agheb, E.
    et al.
    Hashemi, E.
    Mousavi, Seyedali A.
    KTH, School of Electrical Engineering (EES), Electromagnetic Engineering.
    Hoidalen, H. K.
    Study of very fast transient overvoltages in air-cored pulsed transformers2012In: Compel, ISSN 0332-1649, Vol. 31, no 2, p. 658-669Article in journal (Refereed)
    Abstract [en]

    Purpose - The purpose of this paper is to study very fast transient overvoltages (VFTOs) in the secondary winding of air-cored Tesla transformers and also study the resulting electric field stresses. Design/methodology/approach - An exhaustive model based on Multi-conductor Transmission Lines (MTLs) theory has been used. The governing telegraphist's equations have been solved by Finite Difference Time Domain (FDTD) method. Findings - The results demonstrated that there are some overvoltages at the end and middle turns that should be considered in insulation design. The magnitudes of these overvoltages are several times more than the steady state value of the corresponding turn which cause very high electric field stresses. Originality/value - The paper describes results obtained from an original and innovative implementation of FDTD method in transmission line modelling and is applied properly to air-cored pulse transformers.

  • 2274.
    Aghili, Ali
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Ribac, Haris
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Concrete Structures.
    Prediction of early age and time dependent deformations in a massive concrete structure2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The heat development that occurs due to the hydration of cement is important to consider during casting of massive concrete structures. By using computer programs that are based on finite element methods (FEM), simulations can be performed on the heat- and strength development. In this project, a FE program called ConTeSt has been used in order to predict the temperature- and strain development in a massive concrete wall. If the potential risks in a concrete structure are evaluated before casting, economical savings, including a better casting plan could be obtained. The structure under investigation was a concrete wall behind one of the spillways in the hydro power dam of Storfinnforsen. Due to a re-construction of the wall, an opportunity occurred to develop a measurement plan of the casting and perform simulations on the wall.

    A sensitivity analysis was performed in order to investigate the effects on the temperature- and strain development, by varying the cement content, ambient temperature, wind speed and degree of restraint in translation. The results showed, that a higher cement content increased the rate of hydration and hence the temperature in the concrete. Higher wind speeds contributed to more cooling of the concrete which, in some cases, resulted in cracking due to contraction of the material. Cracking due to contraction also occurred when the ambient temperature was decreased. The ambient temperature did not have a significant impact on the rate of hydration, but instead the impact was larger from the initial temperature of the fresh concrete. A higher initial temperature of the fresh concrete increased the rate of hydration, which increased the temperature in the material. The degree of restraint could only be varied in translation in ConTeSt and hence the effect on the strain development was not that significant.

    A crack risk analysis was performed where the developed tensile stresses were compared with the tensile strength of the concrete. The same factors were varied as in the sensitivity analysis. The results showed that the tensile strength was exceeded for most of the cases and thus that the crack risk was high.

    The required equipment, in order to perform the measurements on site, consisted of 7 strain gauges of the module KM-100B from TML Tokyo Sokki Kenkyujo, 2 data loggers of the module Spider-8 from HBM, at least a 25 m ø9 mm 5-core shielded cable and a computer with the software Catman Easy.

  • 2275. Aghion, S.
    et al.
    Ahlén, O.
    Amsler, C.
    Ariga, A.
    Ariga, T.
    Belov, A. S.
    Berggren, Karl
    Physics Department, European Organisation for Nuclear Research, Switzerland.
    Bonomi, G.
    Bräunig, P.
    Bremer, J.
    Brusa, R. S.
    Cabaret, L.
    Canali, C.
    Caravita, R.
    Castelli, F.
    Cerchiari, G.
    Cialdi, S.
    Comparat, D.
    Consolati, G.
    Derking, H.
    Di Domizio, S.
    Di Noto, L.
    Doser, M.
    Dudarev, A.
    Ereditato, A.
    Ferragut, R.
    Fontana, A.
    Genova, P.
    Giammarchi, M.
    Gligorova, A.
    Gninenko, S. N.
    Haider, S.
    Huse, T.
    Jordan, E.
    Jørgensen, L. V.
    Kaltenbacher, T.
    Kawada, J.
    Kellerbauer, A.
    Kimura, M.
    Knecht, A.
    Krasnický, D.
    Lagomarsino, V.
    Lehner, S.
    Magnani, A.
    Malbrunot, C.
    Mariazzi, S.
    Matveev, V. A.
    Moia, F.
    Nebbia, G.
    Nédélec, P.
    Oberthaler, M. K.
    Pacifico, N.
    Petràček, V.
    Pistillo, C.
    Prelz, F.
    Prevedelli, M.
    Regenfus, C.
    Riccardi, C.
    Røhne, O.
    Rotondi, A.
    Sandaker, H.
    Scampoli, P.
    Storey, J.
    Vasquez, M.A. Subieta
    Špaček, M.
    Testera, G.
    Vaccarone, R.
    Widmann, E.
    Zavatarelli, S.
    Zmeskal, J.
    A moiré deflectometer for antimatter2014In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 5, article id 2538Article in journal (Refereed)
    Abstract [en]

    The precise measurement of forces is one way to obtain deep insight into the fundamental interactions present in nature. In the context of neutral antimatter, the gravitational interaction is of high interest, potentially revealing new forces that violate the weak equivalence principle. Here we report on a successful extension of a tool from atom optics—the moiré deflectometer—for a measurement of the acceleration of slow antiprotons. The setup consists of two identical transmission gratings and a spatially resolving emulsion detector for antiproton annihilations. Absolute referencing of the observed antimatter pattern with a photon pattern experiencing no deflection allows the direct inference of forces present. The concept is also straightforwardly applicable to antihydrogen measurements as pursued by the AEgIS collaboration. The combination of these very different techniques from high energy and atomic physics opens a very promising route to the direct detection of the gravitational acceleration of neutral antimatter.

  • 2276.
    Agholme, Alexandra
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Real Estate and Construction Management.
    Hammar, Caroline
    KTH, School of Architecture and the Built Environment (ABE), Real Estate and Construction Management.
    The Effect of Attefall-houses – Can Attefall-houses assist to solve the housing shortage?2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In Stockholm, there is a great shortage of supply on the housing market and many newly

    established on the market find it hard to find a home. During 2014 the Planning and building

    act was changed, allowing for a new kind of small buildings, so called Attefall-houses, of up to 25 sqm to be built without building permit on single family housing units. This thesis evaluates the impact that Attefall-houses have on the housing shortage in Stockholm and how these houses could be property tax assessed.

    As a part of this, the profitability when those are let out have been calculated and whether they have a potential to become more popular has been investigated. Comparisons with foreign renting markets with a more widespread secondary market have furthermore been carried out.

    The thesis is limited towards Attefall-houses classified as residential. Few Attefall-houses have been built and are available for rent. Since the number of transactions pertaining to single family housing units with Attefall-houses was insufficient, market values have been estimated by studying the attitude of market actors, by an income based approach and by a cost approach. In order to get a more perspicuous view of the profitability, repayment times on those let out have been calculated.

    The value an Attefall-house entails on a single family housing unit has been estimated to

    between 200 000 SEK and 300 000 SEK. The repayment times when the Attefall-houses are

    let out and then are sold at this value vary between 5 and 12 years with the current  egislation, depending on financing and municipality. If all rental income had been tax-free, the repayment times would vary between 4 and 7 years instead. If the Attefall-house, on the other hand, is reformed into a tenant ownership unit, the sales prices vary between 1 500 000 and 2 100 000 SEK. According to this, Attefall-houses have the potential to be a profitable investment. A couple of problems and misleading incentives when building and renting them have, however, been found.

    A property with an Attefall-house will get two property tax assessment fees after 15 years. In

    addition, the rental income is taxable, which creates trouble for the property owner but also for the taxation authorities. It is also more economically profitable to re-form the Attefall-houses into tenant-ownership units rather than to keep them as complementary buildings. If the house is re-formed into a tenant ownership unit it is less of a clear alternative for newly established on the market hence not as good complement to the exiting property market as if the owners rent out the dwelling. The process when the houses are built is, furthermore, not as easy as it sounds since the municipality requires detailed documents and the buildings have to meet tough building standards to be allowed to be let out. The processing time before starting decision can be given also varies a lot between different municipalities.

    There are also a lot of ambiguities and grey areas that have been found. It is not clear when

    letting of Attefall-houses should be classified as a business rather than a private activity and it is also not clear on which market value maximum rent and property tax assessment should be based.

    Possibilities for a good investment and economic benefits exist but to make the Attefall-houses more popular, misleading incentives should be removed and incentives for renting should instead be created. The legislation should also be clarified to lower the risk for property owners.

    At the end, time is needed for Attefall-houses to become an established alternative on the

    residential market.

  • 2277.
    Aglert, Johan
    KTH, School of Electrical Engineering (EES), Automatic Control.
    Digital feedback control of the frequency response of a conventional loudspeaker2004Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Automatic control design and Hi-Fi loudspeakers are two areas that not very often are combined. In 1976 Karl Erik Ståhl performed a master thesis project at KTH where he, with analog circuits, made a positive feedback loop to manipulate the mechanical parameters of a loudspeaker. That project introduced the idea to use control design when constructing loudspeakers. In this project this idea is pursued.

    For a subwoofer, the interesting thing from a control perspective is that it is the low frequency range that has to be controlled as opposed to the high frequency range which is normally the case in disturbance and servo problems. This master thesis project will present a solution to this problem where a digital signal processor is used to handle the feed back information. The IMC controller implemented in the processor is based on models derived from data, measured in the tailor made laboratory set-up that was built for the project. In order to satisfy the sampling rate requirements, the complexity of the control algorithm had to be restricted. Despite this limitation in the equipment, the frequency response of the loudspeaker was improved significantly at low frequencies.

  • 2278.
    Agliari, Elena
    et al.
    Dipartimento di Fisica, Universita` degli Studi di Parma, viale G. Usberti 7, 43100 Parma, Italy.
    Barra, Adriano
    Del Ferraro, Gino
    KTH, School of Computer Science and Communication (CSC), Computational Biology, CB.
    Guerra, Francesco
    Tantari, Daniele
    Anergy in self-directed B lymphocytes: A statistical mechanics perspective2013In: Journal of Theoretical Biology, ISSN 0022-5193, E-ISSN 1095-8541, Vol. 375, p. 21-31Article in journal (Refereed)
    Abstract [en]

    Self-directed lymphocytes may evade clonal deletion at ontogenesis but still remain harmless due to a mechanism called clonal anergy. For B-lymphocytes, two major explanations for anergy developed over the last decades: according to Varela theory, anergy stems from a proper orchestration of the whole B-repertoire, such that self-reactive clones, due to intensive feed-back from other clones, display strong inertia when mounting a response. Conversely, according to the model of cognate response, self-reacting cells are not stimulated by helper lymphocytes and the absence of such signaling yields anergy. Through statistical mechanics we show that helpers do not prompt activation of a sub-group of B-cells: remarkably, the latter are just those broadly interacting in the idiotypic network. Hence Varela theory can finally be reabsorbed into the prevailing framework of the cognate response model. Further, we show how the B-repertoire architecture may emerge, where highly connected clones are self-directed as a natural consequence of ontogenetic learning. 

  • 2279.
    Aglén, Lina
    KTH, School of Chemical Science and Engineering (CHE).
    Qualification of Low Value Fuels for Production of Syngas via the WoodRoll Process2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This master thesis project has, on behalf of Cortus Energy AB, investigated how to increase the

    suitability of so called low value fuels for use in the thermochemical conversion process WoodRoll®.

    The theoretical background of the report includes theory on pyrolysis, gasification and ash chemistry,

    as well as a description of WoodRoll® and a comparison between Woodroll® and more conventional

    technologies. A theoretical and an experimental trial have been conducted to investigate methods

    for potentially increasing the ash fusion temperatures of low value fuels. The theoretical study

    compared published articles on leaching and co-gasification. The experimental study was performed

    using thermogravimetric analysis and investigated if blending was a viable alternative for improving

    behavior. Three new types of industrial wastes were also tested.

    Both the theoretically investigated pretreatment methods and the blending were indicated to

    improve the behavior of low value fuels. When compared, blending was deemed to be economically

    favorable over the investigated pretreatment methods. The most economically favorable alternative

    is if two low value fuels with complementing characteristics can be successfully blended. Blending

    would also be easier to integrate with the current WoodRoll® process design and showed promise of

    high fuel flexibility. The behavior of the blends were influenced by their level of homogeneousness,

    a relationship of interest to investigate further in the future.

  • 2280. Agnarsdottir, Margret
    et al.
    Sooman, Linda
    Bolander, Asa
    Stromberg, Sara
    Rexhepaj, Elton
    Bergqvist, Michael
    Ponten, Fredrik
    Gallagher, William
    Lennartsson, Johan
    Ekman, Simon
    Uhlen, Mathias
    KTH, School of Biotechnology (BIO), Proteomics. KTH, School of Biotechnology (BIO), Centres, Albanova VinnExcellence Center for Protein Technology, ProNova.
    Hedstrand, Hakan
    SOX10 expression in superficial spreading and nodular malignant melanomas2010In: Melanoma research, ISSN 0960-8931, E-ISSN 1473-5636, Vol. 20, no 6, p. 468-478Article in journal (Refereed)
    Abstract [en]

    SOX10 is a transcription factor expressed in nerve cells and melanocytes. The aim of this study was to investigate the protein expression pattern of SOX10 in malignant melanoma tumors and to analyze whether the results correlated with clinical parameters and the proliferation marker Ki-67. Furthermore, proliferation and migration were analyzed in three different cell lines employing SOX10 small interfering RNA-mediated silencing. Expression patterns were determined in 106 primary tumors and 39 metastases in addition to 16 normal skin samples and six benign nevi employing immunohistochemistry and tissue microarrays. The immunohistochemical staining was evaluated manually and with an automated algorithm. SOX10 was strongly expressed in the benign tissues, but for the malignant tumors superficial spreading melanomas stained stronger than nodular malignant melanomas (P = 0.008). The staining intensity was also inversely correlated with T-stage (Spearman's rho = -0.261, P = 0.008). Overall survival and time to recurrence were significantly correlated with SOX10 intensity, but not in multivariate analysis including T-stage. With the automated algorithm there was an inverse correlation between the SOX10 staining intensity and the proliferation marker, Ki-67 (rho = -0.173, P = 0.02) and a significant difference in the intensity signal between the benign tissues, the primary tumors and the metastases where the metastases stained the weakest (P <= 0.001). SOX10 downregulation resulted in variable effects on proliferation and migration rates in the melanoma cell lines. In conclusion, the SOX10 intensity level differed depending on the tissue studied and SOX10 might have a role in survival. No conclusion regarding the role of SOX10 for in-vitro proliferation and migration could be drawn. Melanoma Res 20:468-478

  • 2281.
    Agnarsson, Björn
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Surface studies on α–sapphire for potential use in GaN epitaxial growth2009Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    This Licentiate thesis summarizes the work carried out by the author the years 2004 to 2008 at the University of Iceland and the Royal Institute of Technology (KTH) in Sweden. The aim of the project was to investigate the structure of sapphire (alpha-Al2O3) surfaces, both for pure scientific reasons and also for potential use as substrate for GaN-growth by molecular beam epitaxy.

    More generally the thesis describes some surface science methods used for investigating the substrates; the general physical back ground, the experi- mental implementation and what information they can give. The described techniques are used for surface analysis on sapphire substrates which have been treated variously in order to optimize them for use as templates for epi- taxial growth of GaN or related III-V compounds.

    The thesis is based on three published papers.

    The first paper focuses on the formation a thin AlN layer on sapphire, which may act as a buffer layer for potential epitaxial growth of GaN or any related III-V materials. Two types of sapphire substrates (reconstructed and non- reconstructed) were exposed to ammonia resulting in the formation of AlN on the surface. The efficiency of the AlN formation (nitridation efficiency) for the two surfaces was then compared as a function of substrate temperature through photoelectron spectroscopy and low electron energy diffraction. The reconstructed surface showed a much higher nitridation efficiency than the non-reconstructed surface.

    In the second paper, the affect of different annealing processes on the sapphire morphology, and thus its capability to act as a template for GaN growth, was studied. Atomic force microscopy, X-ray diffraction analysis together with ellipsometry measurements showed that annealing in H2 ambient and subse- quent annealing at 1300 °C in O2 for 11 hours resulted in high quality and atomically flat sapphire surface suitable for III-V epitaxial growth.

    The third paper describes the effect of argon sputtering on cleaning GaN surfaces and the possibility of using indium as surfactant for establishing a clean and stoichiometric GaN surface, after such sputtering. Soft sputtering, followed by deposition of 2 ML of indium and subsequent annealing at around 500 °C resulted in a well ordered and clean GaN surface while hard sputtering introduced defects and incorporated both metallic gallium and indium in the surface.

  • 2282.
    Agnarsson, Björn
    et al.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    Göthelid, Mats
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    Olafsson, S.
    Gislason, H. P.
    Karlsson, Ulf O.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    Influence of initial surface reconstruction on nitridation of Al2O3 (0001) using low pressure ammonia2007In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 101, no 1, p. 013519-Article in journal (Refereed)
    Abstract [en]

    The purpose of this study is to investigate the effect of initial surface reconstruction on the nitridation process of Al2O3 (0001). This was done by exposing differently reconstructed sapphire substrates at different temperatures to low pressure ammonia (NH3). Structural and chemical analysis were carried out using low-electron energy diffraction and x-ray photoelectron spectroscopy. The experiments revealed that using low pressure ammonia (P-NH3 < 1 X 10(-5) Torr), no nitridation takes place on (1x1) unreconstructed surfaces. However, when the unreconstructed surface starts to change to a (root 31 x root 31) R +/- 9 degrees reconstructed surface, with increasing substrate temperature, the nitridation becomes successful. When using the initially reconstructed surface, the nitridation is successful even from the lowest temperature used. These results suggest that the initial surface reconstruction has a major effect on the nitridation process. This kinetic behavior has not been reported before, with most nitridation studies mainly focusing on the effect of surface temperature on the resulting surface morphology, rather than the actual kinetics of the process itself.

  • 2283. Agnarsson, Björn
    et al.
    Magnus, Fridrik
    Tryggvason, T. K.
    Ingason, Arni S.
    Leosson, K
    Olafsson, S
    Gudmundsson, Jon Tomas
    University of Iceland.
    Rutile TiO2 thin films grown by reactive high power impulse magnetron sputtering2013In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 545, p. 445-450Article in journal (Refereed)
  • 2284.
    Agnarsson, Björn
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Qi, B.
    Götelid, Mats
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Olafsson, S.
    Gislason, H. P.
    The effect of hard nitridation on Al(2)O(3) using a radio frequency operated plasma cell2011In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 519, no 22, p. 7796-7802Article in journal (Refereed)
    Abstract [en]

    We report on an atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) investigation of hard nitridation of sapphire (alpha.-Al(2)O(3)) substrate, using an Epi UNI-Bulb RF plasma cell at substrate temperatures ranging from 250 to 600 degrees C. Our results show that an AlN(1-x)O(x) layer forms on sapphire after extended nitridation at all temperatures, following a Stranski-Krastanov growth mode, with less islands forming at higher temperatures. We also observe a layer-dependent charging shift in XPS, separating smooth AlN(1-x)O(x) layers from rough AlN(1-x)O(x) islands due to their different electronic coupling to the substrate. Although the island growth is suppressed at higher temperatures, the surface roughness increases at higher temperatures as seen by AFM. We also observe sputtering effects with protrusions and pits.

  • 2285.
    Agnarsson, Björn
    et al.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    Qi, B.
    Szamota-Leandersson, Karolina
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    Olafsson, S.
    Göthelid, Mats
    KTH, School of Information and Communication Technology (ICT), Material Physics, Material Physics, MF.
    Investigation on the role of indium in the removal of metallic gallium from soft and hard sputtered GaN (0001) surfaces2009In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 517, no 21, p. 6023-6026Article in journal (Refereed)
    Abstract [en]

    Cleaning of GaN by argon sputtering and subsequent annealing introduces metallic gallium on the GaN surface. Once formed, this metallic gallium can be difficult to remove. it has a strong influence on the Fermi level position in the band gap and poses a problem for subsequent epitaxial growth on the surface. We present a method of removing metallic gallium from moderately damaged GaN surfaces by deposition of indium, and formation of an In-Ga alloy that can be desorbed by annealing at similar to 550 degrees C. After the In-Ga alloy has desorbed, photoemission spectra show that the Ga3d bulk component becomes narrower indicating a smoother and more homogeneous surface. This is also reflected in a sharper low energy electron diffraction pattern. On heavily damaged GaN surfaces, caused by hard sputtering, larger amount of metallic gallium forms after annealing at 600 degrees C. This gallium readily alloys with deposited indium, but the alloy does not desorb until a temperature of 840 degrees C is reached and even then, traces of both indium and metallic gallium could be found on the surface.

  • 2286.
    Agnarsson, Madelene
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering.
    Larsson, Marie
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering.
    Hjälpmedel vid beräkning av grundvattensänkning för att underlätta prissättning i anbudsfas.2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    Grundvattensänkningar är något som ofta behöver utföras innan konstruktion av anläggningar i jord. Att sätta pris på en grundvattensänkning är inte särskilt lätt när information eller kompetenser saknas som krävs för att göra en rimlig bedömning. Veidekke Entreprenad Anläggning Öst är ett anläggningsföretag som oftast jobbar i generalentreprenadsform. Vid en generalentreprenad så är projekteringen redan gjord och pris ska sättas på de olika posterna som behöver utföras.

    Denna rapport presenterar en förenklad process för kalkylberäkningar i anbudsfas. Därför har en mall har tagits fram åt Veidekke. Denna mall består av fyra representativa typjordar och ekvationer som gör den användarvänlig. För att kontrollera mallens duglighet så testades den sedan på tre projekt som Veidekke utfört grundvattensänkningar på. Mallens beräknade resultat kunde då jämföras med observerade resultat. Det visade sig att mallen ger en god approximation på hur grundvattensänkningen kan se ut och en fingervisning på hur lång tid det kan ta innan stationär grundvattensänkning uppkommer.

  • 2287.
    Agnihotri, Mohit
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Chirikov, R.
    Militano, F.
    Cavdar, C.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Topology Formation in mesh networks considering Role Suitability2016In: 2016 IEEE Wireless Communications and Networking Conference Workshops, WCNCW 2016, Institute of Electrical and Electronics Engineers (IEEE), 2016, p. 421-427Conference paper (Refereed)
    Abstract [en]

    The paper studies various mesh topology formation techniques that can be used to aid the development of large-scale capillary networks. The work focuses on how mesh networks can be established using Bluetooth Low Energy exploiting the heterogeneous characteristics of the devices in the network. A novel algorithm called Topology Formation considering Role Suitability (TFRS) is proposed aiming to maximize the network lifetime. The algorithm employs a newly introduced metric called role suitability metric (RSM) to assign the best role among master, relay and slave to a participating device. The RSM metric is computed from device characteristics including, but not limited to, energy, mobility and computational capability. We use system-level simulation to evaluate the performance of the proposed algorithm against a reference under a homogeneous deployment scenario consisting of heterogeneous devices. Results show that the network lifetime can be improved significantly when the topology is formed considering the device characteristics for both master role selection and relay selection. TFRS can achieve 20% to 40% higher network lifetime depending on the deployment characteristics over the reference algorithm.

  • 2288.
    Agnihotri, Mohit
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Chirikov, R.
    Militano, F.
    Cavdar, Cicek
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Topology formation in mesh networks considering role suitability2016In: IEEE Wireless Communications and Networking Conference, WCNC, IEEE, 2016Conference paper (Refereed)
    Abstract [en]

    The paper studies various mesh topology formation techniques that can be used to aid the development of large-scale capillary networks. The work focuses on how mesh networks can be established using Bluetooth Low Energy exploiting the heterogeneous characteristics of the devices in the network. A novel algorithm called Topology Formation considering Role Suitability (TFRS) is proposed aiming to maximize the network lifetime. The algorithm employs a newly introduced metric called role suitability metric (RSM) to assign the best role among master, relay and slave to a participating device. The RSM metric is computed from device characteristics including, but not limited to, energy, mobility and computational capability. We use systemlevel simulation to evaluate the performance of the proposed algorithm against a reference under a homogeneous deployment scenario consisting of heterogeneous devices. Results show that the network lifetime can be improved significantly when the topology is formed considering the device characteristics for both master role selection and relay selection. TFRS can achieve 20% to 40% higher network lifetime depending on the deployment characteristics over the reference algorithm.

  • 2289.
    Agnihotri, Mohit Kumar
    KTH, School of Information and Communication Technology (ICT).
    Energy efficient topology formation for Bluetooth mesh networks using heterogeneous devices2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Internet of things (IoT) is the latest trend in our living spaces allowing machine to machine (M2M) communications at the extensive scale. To enable massive M2M communication and portable devices to run on limited power supplies for the extended duration of time, low-cost energy efficient wireless technologies are needed. Among the many competing technologies including Wi-Fi, Bluetooth has shown the potential to be one of the strong candidates to act as the connectivity solution for the IoT especially after the introduction of Bluetooth Low Energy (BLE). Nowadays BLE is one of the biggest players in the market of short-range wireless technologies. By 2020, nearly 30 billion BLE devices in the form of mobile phones, tablets, sports utilities, sensors, security systems and health monitors are expected to be shipped. This proliferation of low-cost devices may for the first time actualize the vision of IoT.

    This thesis studies various mesh topology formation techniques that can be used to aid the development of large-scale networks in capillary networks focusing on BLE. In particular, the thesis focuses on how mesh networks can be established over BLE communications especially exploiting the heterogeneous characteristics of the devices. A novel algorithm is proposed called Topology Formation considering Role Suitability (TFRS) to maximize the network lifetime. The algorithm uses a newly introduced metric called role suitability metric (RSM) to assign the best role among master, relay and slave to a device. The RSM metric bases its decision on various device characteristics including, but not limited to, energy, mobility, and computational capability. We use the system-level simulation to evaluate the performance of the proposed algorithm against a reference under homogeneous deployment scenario consisting of heterogeneous devices.

    Results show that the network lifetime can be improved significantly when the topology is formed considering the device characteristics for both master role selection and relay selection. TFRS can achieve moderate improvements ranging from 20% to 40% varying on the deployment characteristics over the reference case.

  • 2290.
    Agnér, Christian
    et al.
    KTH, School of Electrical Engineering (EES).
    Blomqvist, Anneli
    KTH, School of Electrical Engineering (EES).
    Evaluating Stress through Machine Learning based on Brain Activity Data2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    More people are experiencing stressrelatedsymptoms, which is not only causing worsenhealth, but also causing economical drawbacks for thesociety, businesses and individuals. The aim of thisproject is to create a tool that evaluates stress frombrain activity data and can help to avoid develop thesymptoms.An EMOTIV Epoch EEG headset is used to recorddata. The stress level is evaluated from the brainactivity data by the parameters, feeling of pleasure(valence) and the mental workload. k-NN machinelearning is utilized to create a valence classificationalgorithm and the theta power density spectrum is usedto determine the workload. Eye movement disturbancesin the recordings are also addressed.Tests with Stroop word color games as stress stimuliare conducted and the project concludes that it ispossible to determine the stress level correctly, onaverage, 17.56% and when allowing one level difference,48.71% .

  • 2291.
    AGORAS, DIMITRIS
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.), Industrial Marketing and Entrepreneurship.
    Building Information Modeling (BIM) Adoption Barriers: An Architectural Perspective2018Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Building Information Modeling (BIM) is the latest development in the Architecture, Engineering and Construction (AEC) Industry. This development can be used for planning, design, construction, operation and maintenance of any facility. The majority of the users of BIM technology are architects. Although its benefits had been highlighted and underlined especially in comparison with older developments such us Computer Aided Design (CAD) tools, its implementation is considered still in an early stage due to low adoption from architects.

    Right now in Sweden and more specifically in the Stockholm area, the construction sector is booming due to the increased demand for housing.  Thus, there is an increased demand for more houses in a shorter time.

    BIM is a technology that can enhance the society in terms of design and construction with regard to the building environment. This can be achieved by avoiding human errors, decreasing project costs, increasing the productivity and quality, and reducing the project delivery time. Moreover, BIM can assist the management team in maintaining and operating different facilities.

    The focus of this research is on the barriers to adopting BIM technology in architectural companies. Furthermore, the attempt will be to investigate the individual, organizational and technical aspects that affect BIM adoption.  This study will implement a qualitative research method by in-depth interviewing four professionals in the area of architectural design.

    This investigation will be driven by the main research question, which is: What are the barriers to adopting Building Information Modeling (BIM) in architectural companies?

  • 2292. Agosta, L.
    et al.
    Metere, A.
    Dzugutov, Mikhail
    KTH.
    Hexatic smectic phase with algebraically decaying bond-orientational order2018In: Physical review. E, ISSN 2470-0045, E-ISSN 2470-0053, Vol. 97, no 5, article id 052702Article in journal (Refereed)
    Abstract [en]

    The hexatic phase predicted by the theories of two-dimensional melting is characterized by the power-law decay of the orientational correlations, whereas the in-layer bond orientational order in all the hexatic smectic phases observed so far was found to be long range. We report a hexatic smectic phase where the in-layer bond orientational correlations decay algebraically, in quantitative agreement with the hexatic ordering predicted by the theory for two dimensions. The phase was formed in a molecular dynamics simulation of a one-component system of particles interacting via a spherically symmetric potential. The present results thus demonstrate that the theoretically predicted two-dimensional hexatic order can exist in a three-dimensional system.

  • 2293. Agostinho, A.
    et al.
    Kouznetsova, A.
    Hernández-Hernández, A.
    Bernhem, Kristoffer
    KTH, School of Engineering Sciences (SCI), Applied Physics. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Blom, Hans
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biophysics. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Brismar, Hjalmar
    KTH, School of Engineering Sciences (SCI), Applied Physics, Biophysics. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Höög, C.
    Sexual dimorphism in the width of the mouse synaptonemal complex2018In: Journal of Cell Science, ISSN 0021-9533, E-ISSN 1477-9137, Vol. 131, no 5, article id jcs212548Article in journal (Refereed)
    Abstract [en]

    Sexual dimorphism has been used to describe morphological differences between the sexes, but can be extended to any biologically related process that varies between males and females. The synaptonemal complex (SC) is a tripartite structure that connects homologous chromosomes in meiosis. Here, aided by superresolution microscopy techniques, we show that the SC is subject to sexual dimorphism, in mouse germ cells. We have identified a significantly narrower SC in oocytes and have established that this difference does not arise from a different organization of the lateral elements nor from a different isoform of transverse filament protein SYCP1. Instead, we provide evidence for the existence of a narrower central element and a different integration site for the C-termini of SYCP1, in females. In addition to these female-specific features, we speculate that post-translation modifications affecting the SYCP1 coiled-coil region could render a more compact conformation, thus contributing to the narrower SC observed in females.

  • 2294. Agostinho, Ana
    et al.
    Manneberg, Otto
    KTH, School of Engineering Sciences (SCI), Applied Physics. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    van Schendel, Robin
    Hernandez-Hernandez, Abrahan
    Kouznetsova, Anna
    Blom, Hans
    KTH, School of Engineering Sciences (SCI), Applied Physics, Cell Physics. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Brismar, Hjalmar
    KTH, School of Engineering Sciences (SCI), Applied Physics, Cell Physics. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Höög, Christer
    High density of REC8 constrains sister chromatid axes and prevents illegitimate synaptonemal complex formation2016In: EMBO Reports, ISSN 1469-221X, E-ISSN 1469-3178, Vol. 17, no 6, p. 901-913Article in journal (Refereed)
    Abstract [en]

    During meiosis, cohesin complexes mediate sister chromatid cohesion (SCC), synaptonemal complex (SC) assembly and synapsis. Here, using super-resolution microscopy, we imaged sister chromatid axes in mouse meiocytes that have normal or reduced levels of cohesin complexes, assessing the relationship between localization of cohesin complexes, SCC and SC formation. We show that REC8 foci are separated from each other by a distance smaller than 15% of the total chromosome axis length in wild-type meiocytes. Reduced levels of cohesin complexes result in a local separation of sister chromatid axial elements (LSAEs), as well as illegitimate SC formation at these sites. REC8 but not RAD21 or RAD21L cohesin complexes flank sites of LSAEs, whereas RAD21 and RAD21L appear predominantly along the separated sister-chromatid axes. Based on these observations and a quantitative distribution analysis of REC8 along sister chromatid axes, we propose that the high density of randomly distributed REC8 cohesin complexes promotes SCC and prevents illegitimate SC formation.

  • 2295.
    Agostini Fantini, Francesco
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Izaguirre Carbonell, Javier
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    GIS-Based approach to estimate the energy requirements of the post-harvest activities in Souss-Massa basin in Morocco2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Over the last decades the Moroccan agriculture has passed through a complete transformation: due to the low workforce cost and its favourable climate, the sector has attracted the attentions of national and foreign investment and thus has expanded rapidly. Among the different productions, tomatoes proved to be one of the most profitable, generating 4.867 billion dirhams in 2016 from exports. In order to remain competitive and attractive, the sector needs to be constantly monitored and controlled: abuses of the environment and of available resources may affect or even compromise the future of the Moroccan agriculture. Energy in particular has a remarkable role and has to be analysed in order to quantify its impact over costs and environment. The aim of this study is to build a GIS-based model of tomato’s postharvest system and study the agriculture and energy nexus interactions in the Souss-Massa region. Post harvesting activities such as: Transportation, conditioning, packaging, storing and transformation of tomato, occurs within Souss-Massa’s geographical boundaries and have been the focus of in this study. Results of current system highlight the dominance of packaging activity as the main energy consumer with 77%, followed by storing, transportation and transformation with 14 %, 6% and 3% respectively. In terms of cost the transportation becomes the most relevant activity due to the cost of fuels and transport conditions. Energy costs and wastes in transportation represent 15% of the local revenues (9% Transportation, 5% Packaging and 1% Storing). Four different scenarios about the future situation have been implemented to measure the possible impact of changes in the different activities: Business as Usual (BAU), Transport Efficiency (TE), Waste Reduction (WR) and Renewable Penetration (RP). -3- In BAU current trends have been followed to forecast the total production, the export and the power generation. In TE trucks with bigger capacity have been implemented and in WR refrigeration is considered in every transport stage. Finally, in RP higher renewable penetration has been considered

  • 2296. Agranovsky, M.
    et al.
    Khavinson, D.
    Shapiro, Harold
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.), Mathematics (Div.).
    Malmheden's theorem revisited2010In: Expositiones mathematicae, ISSN 0723-0869, E-ISSN 1878-0792, Vol. 28, no 4, p. 337-350Article in journal (Refereed)
    Abstract [en]

    In 1934 Malmheden [16] discovered an elegant geometric algorithm for solving the Dirichlet problem in a ball. Although his result was rediscovered independently by Duffin (1957) [8] 23 years later, it still does not seem to be widely known. In this paper we return to Malmheden's theorem, give an alternative proof of the result that allows generalization to polyharmonic functions and, also, discuss applications of his theorem to geometric properties of harmonic measures in balls in R-n.

  • 2297.
    Agrawal, Harshit
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Vehicle Dynamics.
    Gustafsson, Jacob
    Investigation of active anti-roll bars and development of control algorithm2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Active anti-roll bars have recently found greater acceptance among premium car manufacturers and optimal application of this technology has emerged as an important field of research. This thesis investigates the potential of implementing active anti-roll bars in a passenger vehicle with the purpose of increasing customer value. For active anti-roll bars, customer value is defined in terms of vehicle’s ride comfort and handling performance. The objective with this thesis is to demonstrate this value through development of a control algorithm that can reflect the potential improvement in ride comfort and handling. A vehicle with passive anti-roll bars is simulated for different manoeuvres to identify the potential and establish a reference for the development of a control algorithm and for the performance of active anti-roll bars. While ride is evaluated using single-sided cosine wave and single-sided ramps, handling is evaluated using standardized constant radius, frequency response and sine with dwell manoeuvres.The control strategy developed implements a combination of sliding mode control, feed forward and PI-controllers. Simulations with active anti-roll bars showed significant improvement in ride and handling performance in comparison to passive anti-roll bars. In ride comfort, the biggest benefit was seen in the ability to increase roll damping and isolating low frequency road excitations. For handling, most significant benefits are through the system’s ability of changing the understeer behaviour of the vehicle and improving the handling stability in transient manoeuvres. Improvement in the roll reduction capability during steady state cornering is also substantial. In conclusion, active anti-roll bars are undoubtedly capable of improving both ride comfort and handling performance of a vehicle. Although the trade-off between ride and handling performance is significantly less, balance in requirements is critical to utilise the full potential of active anti-roll bars. With a more comprehensive control strategy, they also enable the vehicle to exhibit different driving characteristics without the need for changing any additional hardware.

  • 2298.
    Agrawal, Navneet
    KTH, School of Electrical Engineering (EES), Information Science and Engineering.
    Machine Intelligence in Decoding of Forward Error Correction Codes2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A deep learning algorithm for improving the performance of the Sum-ProductAlgorithm (SPA) based decoders is investigated. The proposed Neural NetworkDecoders (NND) [22] generalizes the SPA by assigning weights to the edges ofthe Tanner graph. We elucidate the peculiar design, training, and working of theNND. We analyze the edge weight’s distribution of the trained NND and providea deeper insight into its working. The training process of NND learns the edgeweights in such a way that the effects of artifacts in the Tanner graph (such ascycles or trapping sets) are mitigated, leading to a significant improvement inperformance over the SPA.We conduct an extensive analysis of the training hyper-parameters affectingthe performance of the NND, and present hypotheses for determining theirappropriate choices for different families and sizes of codes. Experimental resultsare used to verify the hypotheses and rationale presented. Furthermore,we propose a new loss-function that improves performance over the standardcross-entropy loss. We also investigate the limitations of the NND in termsof complexity and performance. Although the SPA based design of the NNDenables faster training and reduced complexity, the design constraints restrictthe neural network to reach its maximum potential. Our experiments show thatthe NND is unable to reach Maximum Likelihood (ML) performance thresholdfor any plausible set of hyper-parameters. However for short length (n 128)High Density Parity Check (HDPC) codes such as Polar or BCH codes, theperformance improvement over the SPA is significant.

  • 2299. Agrawal, P
    et al.
    Chuah, M C
    Zander, Jens
    KTH, Superseded Departments (pre-2005), Wireless at KTH.
    Multimedia multicast/broadcast services in 3G/4G networks2004In: IEEE Communications Magazine, ISSN 0163-6804, E-ISSN 1558-1896, Vol. 42, no 2, p. 62-63Article in journal (Other academic)
  • 2300.
    Agrawal, Rohit
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Semi-Automated Formalization and Verification of Automotive Requirements using Simulink Design Verifier2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The complexity of embedded software in the automotive domain is ever-increasing due to increase in the no. of features aimed at providing more advanced solutions. This has greatly favored the incorporation of Model Based Design workflow in the software development lifecycle to handle complexities in different development phases. Simulation based testing is widely used in automotive domain to identify design errors in models. However, formal verification as opposed to simulation based testing has an inherent advantage of traversing the entire design space systematically and proving mathematically that the system satisfies the requirements. Lack of knowledge in formal methods and system requirements in their present form in natural text, form the biggest hindrances in making formal verification a reality in the automotive domain. Specification Patterns through their constrained English grammar have shown some promise in requirements specification by avoiding the diverse language structure of the natural language. Simulink Design Verifier (SLDV), a verification tool integrated with MATLAB/Simulink alleviates the need of a separate formal model and leverages on Simulink’s capability to model requirements. This thesis investigates various challenges with regard to formal verification with Simulink Design Verifier and Specification Patterns with possibilities of semi-automating the process. Fuel Level Display System, a case study from Scania is specifically dealt with as a real industry example, to investigate the expressivity of Simulink Design Verifier for modelling requirements, its efficiency as a verification tool, usability of Specification Patterns and insufficiencies of requirements in natural text. The investigation recommends formal verification to be carried out by system engineers/developers with help of Specification Patterns and SLDV, provided that complex behavior is specified within a proposition/non-literal term of Pattern. This complex behavior can be modelled with Simulink and SLDV blocks. The modelling framework of patterns in SLDV can be used to verify the requirements. The limitations posed by SLDV in modelling some aspects of requirements can be dealt with by making suitable changes to system model by system developers.

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