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  • 11651.
    Berggren, Fredrik
    et al.
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Ben Slimane, Slimane
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Successive Interference Cancellation in Multi-Rate DS-CDMA Systems2003In: PIMRC 2003: 14TH IEEE 2003 INTERNATIONAL SYMPOSIUM ON PERSONAL, INDOOR AND MOBILE RADIO COMMUNICATIONS PROCEEDINGS, VOLS 1-3 2003 / [ed] Gong K, Niu ZH, Beijing: PUBLISHING HOUSE ELECTRONICS INDUSTRY , 2003, p. 1752-1756Conference paper (Refereed)
    Abstract [en]

    In this work, a linear DS-CDMA receiver utilizing soft feedback interference cancellation is analyzed. To be able to meet diverse QoS requirements, we introduce a power control scheme that takes into account multi-QoS objectives, as well as the impact of imperfect interference cancellation. Our results are general and provide a framework for capacity comparison for many proposed linear successive cancellation receiver models. Several receiver modifications are included, partial interference cancellation: when only part of the signal is canceled, and limited cancellation; when not every signal is canceled. We derive the minimum power solution, from which the resulting receiver capacity can be fully characterized. The results show that there are large gains in user capacity from interference cancellation when the Eb/Io requirements are high. However, regardless of the required targets, we find that the maximum capacity is always achieved through partial successive interference cancellation. It is also found that worse performance than conventional single-user detection can occur.

  • 11652.
    Berggren, Fredrik
    et al.
    KTH, School of Information and Communication Technology (ICT).
    Bria, Aurelian
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Veronesi, Riccardo
    Multi-radio resource management for ambient networks2005In: IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC, IEEE , 2005, p. 942-946Conference paper (Refereed)
    Abstract [en]

    The Ambient Networks concept targets forthcoming dynamic communication environments, characterized by the presence of a multitude of different wireless devices, radio access technologies, network operators and business actors, which can form instant inter-network agreements with each other. MultiRadio Resource Management (MRRM) mechanisms, coordinating several radio accesses, fulfill a key role for providing wireless services with improved resource efficiency, coverage and service quality. This paper presents an MRRM concept for Ambient Networks, describes the principal MRRM functions and discusses design criteria.

  • 11653.
    Berggren, Fredrik
    et al.
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Jäntti, Riku
    Faculty of Computer Science Department of Information Technology University of Vaasa FIN-65101, Vaasa, FINLAND.
    Asymptotically Fair Scheduling on Fading Channels2002In: IEEE 56TH VEHICULAR TECHNOLOGY CONFERENCE, VTC FALL 2002, VOLS 1-4, PROCEEDINGS, New York: IEEE , 2002, p. 1934-1938Conference paper (Refereed)
    Abstract [en]

    The problem of scheduling data for a DS-CDMA downlink, over a fading channel is considered. We show that high speed downlink data is most efficiently supported by time division of the channel, by letting only one single user in each cell access the channel at a time. For efficient resource utilization, some form of scheduling is required to determine which user should transmit at any given instant of time. Scheduling algorithms of different adaptation rate are suggested and compared. To avoid unfair performance, an algorithm that schedules a user to transmit when its channel is the `relatively best' is analyzed. We show that this algorithm asymptotically provides the same fairness as a round robin scheduler, but the throughput is significantly improved. For a Rayleigh fading channel, we show that the scheduling gain is in fact equal to the gain of a selection diversity scheme.

  • 11654.
    Berggren, Fredrik
    et al.
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Jäntti, Riku
    Faculty of Computer Science Department of Information Technology University of Vaasa FIN-65101, Vaasa, FINLAND.
    Asymptotically Fair Transmission Scheduling over Fading Channels2004In: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 3, no 1, p. 326-336Article in journal (Refereed)
    Abstract [en]

    In this work, the problem of scheduling delay insensitive data over a DS-CDMA downlink fading channel is considered. We consider the case where only one user at a time is allowed to transmit. As the channels can be considered to vary asynchronously among the users, multiuser diversity gains can be obtained by exploiting channel adaptive scheduling. For this, schedulers of different adaptation rate are suggested and compared. In particular we analyze a simple fast scheduler that schedules a user to transmit when its channel is good relative to its mean. This scheduler is resource fair in the sense it can provide the users with the same asymptotical channel access. We show that the achievable scheduling gain compared to round robin is equal to the gain of a selection diversity scheme. The scheduling gain is determined, both on closed-form and by numerical integration, for several scenarios, including multicellular systems and the effect of time delayed channel estimates. The results show that the scheduling gain is larger for channels with low average quality.

  • 11655.
    Berggren, Fredrik
    et al.
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Jäntti, Riku
    Faculty of Computer Science Department of Information Technology University of Vaasa FIN-65101, Vaasa, FINLAND.
    Multiuser Scheduling over Rayleigh Fading Channels2003Conference paper (Refereed)
    Abstract [en]

    Forthcoming wideband wireless systems are supposed to support services with loose delay requirements, which allows for scheduling of data. In this work we investigate fast transmission scheduling for downlink CDMA over a Rayleigh fading channel. For a logarithmic relation between the channel quality and the effective transmission rate, merely scheduling one user at a time may not result in maximum channel utilization. Therefore, we analyze the benefits of scheduling several users at a time with a suggested scheduler, containing regular CDMA as a special case. We consider a resource fair scheduler with the objective to asymptotically allocate the same amount of energy to all users. We derive the scheduling gain on closed-form and determine its limit values for both high and low average channel quality. The results show that the better the average channel quality becomes, the more users should be allowed to transmit simultaneously.

  • 11656.
    Berggren, Fredrik
    et al.
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Kim, Seong-Lyun
    Radio Resource Management & Optimization Laboratory Informations and Communications University School of Engineering Yusong P.O. Box 77, Taejon, 305-600, KOREA.
    Energy-Effcient Control of Rate and Power in DS-CDMA Systems2004In: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 3, no 3, p. 725-733Article in journal (Refereed)
    Abstract [en]

    The quality of service in DS-CDMA can be controlled by a suitable selection of processing gain and transmission powers. In this paper, distributed control of rate and power for best effort data services is considered. In particular, we elaborate on the problem of how to control the transmission rates for maximizing system throughput while simultaneously minimizing the transmission powers. We assume a practical scenario, where every user has a finite set of discrete transmission rates and propose a simple heuristic rate allocation scheme, greedy rate packing (GRP), applicable in both upand downlink. The scheme can be interpreted as a practical form of water-filling, in the sense that high transmission rates are allocated to users having high link gains and low interference. We show that under certain conditions, GRP will give maximum throughput and that it can be extended to guarantee a minimum data rate while maximizing network excess capacity. We suggest and analyze a distributed power control control algorithm to control the intercell interference when GRP is applied to a multicellular system. Numerical results show that the proposed transmission scheme can significantly decrease the power levels while maintaining high throughput.

  • 11657.
    Berggren, Fredrik
    et al.
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Kim, Seong-Lyun
    Radio Resource & Management Optimization Laboratory, ICU Graduate School of Management, Information and Communications University, Korea.
    Energy-Efficient Downlink Power Control and Scheduling for CDMA Non-Real Time Data2000Conference paper (Refereed)
    Abstract [en]

    The performance of CDMA systems highly depends on the success in  managing interference arising from both intercell and intra-cell transmissions. Interference management in terms of power control has been  widely studied. In this paper we consider non-real time data services,  where in addition to power control, there is the possibility of scheduling  intra-cell transmissions. One such schedule is to use time division so  that users transmit in a one-by-one fashion within each cell. We com-  bine this form of scheduling with a suggested distributed power control  algorithm for the inter-cell interference management. We show that the  algorithm converges to a power allocation that supports the non-real  time data users with the minimum power while meeting requirements  on average data rate.

  • 11658.
    Berggren, Fredrik
    et al.
    KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
    Litjens, Remco
    TNO ICT, The Netherlands.
    Performance analysis of access selection and transmit diversity in multi-access networks2006In: MOBICOM 2006, ACM , 2006, p. 251-261Conference paper (Refereed)
    Abstract [en]

    Motivated by the "beyond 3g" vision of radio access network integration and coordinated radio resource management, a purely analytical performance assessment is presented for a single access point integrating multiple radio accesses. Principal focus is placed on the evaluation of multi-user diversity, multi-access diversity and trunking gains. Scenarios with persistent and non-persistent data flows are investigated, concentrating on throughput and transfer time performance, respectively. A number of numerical experiments are included in order to quantify the relative contribution of the distinguished aspects to the performance gain. These experiments indicate that the exploitation of multi-user diversity with a channel-aware access selection scheme attains the most significant gains, while also the trunking gain that is due to an above-proportional performance enhancement when aggregating system-specific capacities, is noted to be significant. The assignment of multiple accesses to a given flow is demonstrated to have limited potential.

  • 11659.
    Berggren, Fredrik
    et al.
    KTH, Superseded Departments, Wireless at KTH.
    Queseth, Olav
    KTH, Superseded Departments, Wireless at KTH.
    Zander, Jens
    KTH, Superseded Departments, Wireless at KTH.
    Asp, Börje
    Swedish Defence Research Agency (FOI).
    Jönsson, Christian
    Swedish Defence Research Agency (FOI).
    Stenumgaard, Peter
    Swedish Defence Research Agency (FOI).
    Kviselius, Niklas Z
    CIC, Stockholm School of Economics.
    Thörngren, Bertil
    CIC, Stockholm School of Economics.
    Dynamic Spectrum Access, Phase 1 Scenarios and research challenges2004Report (Other academic)
    Abstract [en]

    The currently used mechanisms for spectrum management are a contributing factor to the long lead times from innovation to market in wireless technologies andsystems. This has in turn been a major contributing factor to the dominance of the large telecom companies in the European and World markets, whereas very few innovative enterprises have exhibited consistent growth, although the technicalcompetence in Sweden is very high in this area. Alternative spectrum management regimes, such as the introduction of "unlicensed bands" have proven very effective in lowering entry thresholds for smaller companies (e.g the WLAN business). In addition, experts claim that the spectrum requirements for communication purposes will increase by as much as 200-300 % up to 2010. At the same time the actual usage of the electromagnetic spectrum is very inefficient.

    The project aims at studying new more, flexible, spectrum allocation regimeswhich, in combination with new technologies, such as multi-radio access, novelbroadband access techniques, software defined radio and spatial techniques (e.g.smart antennas, multi-hop schemes) have the potential of lowering the entry thresholds for new actors and provide radical improvement to the efficiency ofspectrum usage. Further the aim is to investigate the economic and regulatory consequences of such Dynamic Spectrum Access technologies and managementregimes. The results will provide input to future policies in spectrum management. The project has been divided into a first, pre-study phase and a second, research phase. The first phase was launched in Dec of 2004 and the second phase is planned to start in Jan 2005. The first phase of the project, reported here, has the aim toprovide a qualitative assessment of the potential benefits of dynamic spectrum access regimes. The analysis in the report and other studies in the area, indeed indicate there is a potential to both lower the entry thresholds for new actors as well as provide radical improvement to the efficiency of spectrum usage. The area isdefinitely of significant issues and the project should be continued studying the DSA concepts in more detail.

    Further, using a systematic procedure, a number of critical areas and bottleneck problems were identified. Our conclusion is that more research is needed in theseareas to achieve the above mentioned benefits. As `side effect' in this procedure, a number of novel and interesting spectrum management concepts were derived, e.g.the `real-time spectrum trading' and `use rights' concepts. Out of this gross list ofinterest problems, a number of highly important problems were selected, matching the competence of the project team. These problems are proposed to be the focus ofthe next phase in the project.

    Finally, the report provides an overview of the most important ongoing research and policy-making activities in the DSA-area.

  • 11660.
    Berggren, Frida
    KTH, School of Chemical Science and Engineering (CHE).
    Development of an Expancel Product through Optimisation of Polymer Composition and the Suspension Stabilising System2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Thermally expandable microspheres are spherical particles around 5-­‐40 µm in size, consisting of a polymeric shell in which a blowing agent has been encapsulated. The microspheres are expanded upon heating, resulting in a particularly low density. Microspheres are therefore suitable to use as light weight filler or as foaming agent.

    AkzoNobel is world leading in the production of expandable microspheres, which are commercialised under the name Expancel. Sustainability is a great focus at AkzoNobel and two issues that AkzoNobel works with today is to develop products free from chlorine and Me1. The aim with this thesis has been to investigate whether it is possible to produce microspheres free from these chemicals and to see if they can be a more sustainable alternative to one of the existing Expancel grades.

    In this study, the microspheres have been produced through free radical suspension polymerisation and analysed by measuring mainly the particle size and expansion properties. The polymeric shell was composed of the monomers acrylonitrile, methacrylonitrile, and methyl acrylate. The main focus has been to evaluate the silica-­‐based stabilisation system, which stabilise the monomer droplets during the suspension polymerisation. The stabilisation is possible due to the formation of silica flocs that is adsorbed on the surface of the droplets. It has been investigating how different parameters, e.g. amount of stabiliser or mixing procedure, affects the formation of silica flocs and the stabilisation of monomer droplets.

    For the silica-­‐based system, it was found that the mixing order, stirring rate, and amount of stabilisers affect the formation of flocs. It was also seen that the amount of stabiliser affect the stabilisation of droplets, and that some stabilisers is more significant than others.

    Microspheres without chlorine and Me1 have successfully been produced in laboratory scale (50 mL and 1 L). The expansion and size of the microspheres produced in this study was relatively similar to one of the existing Expancel grades. However, the reproducibility of polymerisations in 1 litre reactors has been poor.

  • 11661.
    Berggren, Frida
    et al.
    KTH, School of Chemical Science and Engineering (CHE).
    Johansson, Jim
    KTH, School of Chemical Science and Engineering (CHE).
    Lönnemark, Lena
    KTH, School of Chemical Science and Engineering (CHE).
    Tisell, Joakim
    KTH, School of Chemical Science and Engineering (CHE).
    Proteinbaserade elastomerer2012Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Projektet behandlar möjligheten att från vetegluten kunna skapa ett gummielastiskt material via

    vulkning med svavel. Grundtanken bakom försöken är att proteinkedjorna i gluten innehåller

    aminosyran cystein som med sin tiolgrupp skall kunna bilda nätverk av tvärbindningar. De redan

    existerande intramolekylära svavelbryggorna önskas bli intermolekylära och med

    vulkningskemikalierna skall längre bryggor bildas. Vi har behandlat proverna i en varmpress

    tillsammans med traditionella reaktanter för vulkning av rågummi (cis-isopren).

    Dessvärre har det nya materialet i väldigt liten utsträckning visat prov på elastiska egenskaper. Ingen

    eller svag återgång till ursprungstillstånd har observerats. Det segaste materialet är det som inte

    innehåller vulkningskemikalier och enbart består av gluten och mjukgöraren glycerol. Ett stort

    problem har varit att kemikalierna har varit svåra att finfördela vilket medfört att materialet blivit

    inhomogent. Oregelbundenheterna har givit upphov till revor och materialet har spruckit i de svaga

    punkterna vid mekaniskt dragprov.

  • 11662. Berggren, K.
    et al.
    Nilsson, A.
    Johansson, G.
    Bandmann, N.
    Nygren, Per-Åke
    KTH, Superseded Departments, Biotechnology.
    Tjerneld, F.
    Partitioning of peptides and recombinant protein-peptide fusions in thermoseparating aqueous two-phase systems: effect of peptide primary structure2000In: Journal of Chromatography B, ISSN 0378-4347, Vol. 743, no 02-jan, p. 295-306Article in journal (Refereed)
    Abstract [en]

    Genetic engineering has been used for fusion of peptides, with different length and composition, on a protein to study the effect on partitioning in an aqueous two-phase system. The system was composed of dextran and the thermoseparating ethylene oxide-propylene oxide random copolymer, EO30PO70. Peptides containing tryptophan, proline, arginine or aspartate residues were fused at the C-terminus of the recombinant protein ZZ-cutinase. The aim was to find effective tags for the lipolytic enzyme cutinase for large-scale extraction. The target protein and peptide tags were partitioned separately and then together in the fusion proteins in order to gain increased understanding of the influence of certain amino acid residues on the partitioning. The salt K2SO4 was used to reduce the charge dependent salt effects on partitioning and to evaluate the contribution to the partition coefficient from the hydrophobic-hydrophilic properties of the amino acid residues. The effect of Trp on peptide partitioning was independent of the difference in primary structure for (Trp)n, (Trp-Pro)n, (Ala-Trp-Trp-Pro)n and was only determined by the number of Trp. The effect of the charged residues, Arg and Asp, was dependent on the surrounding residues, i.e. if they were situated next to Trp or not. The partitioning behaviour observed for the peptides was qualitatively and in some cases also quantitatively the same as for the fusion proteins. The effect of the salts sodium perchlorate and triethylammonium phosphate on the partitioning was also studied. The salt effects observed for the peptides were qualitatively similar to the effects observed for the fusion proteins.

  • 11663. Berggren, K.
    et al.
    Tjerneld, F.
    Veide, Andres
    KTH, Superseded Departments, Biotechnology.
    Peptide fusion tags with tryptophan and charged residues for control of protein partitioning in PEG-potassium phosphate aqueous two-phase systems2000In: Bioseparation (Dordrecht), ISSN 0923-179X, E-ISSN 1573-8272, Vol. 9, no 2, p. 69-80Article in journal (Refereed)
    Abstract [en]

    A partition study with peptides and recombinant proteins in poly(ethylene glycol)4000-potassium phosphate aqueous two-phase systems has been performed. The aim was to study to what extent the insertion of charged residues could affect protein partition in addition to the already observed effects of tryptophan residues. The model proteins used are based on a staphylococcal protein A derivative, Z, and modified by the insertion of peptide tags close to the C-terminus. The tags differed with respect to their content of both Trp, negatively (Asp) and positively charged (Lys) amino acid residues. The same partitioning trends were observed for the peptides and fusion proteins. The effect of Trp residues was to direct the partitioning towards the PEG phase. The insertion of two negatively charged (Asp) residues into a Trp(4)-tag enhanced the partition towards the PEG phase even more. The introduction of positively charged (Lys) residues in addition to Trp residues, on the other hand, pulled the peptide or protein towards the potassium phosphate phase. The partitioning of peptides gave a good qualitative picture of the effect of the peptide on partitioning when fused to the protein. The efficiencies of the tags were calculated based on partitioning of tags and fusion proteins, and tag efficiencies generally varied between 60 and 85%.

  • 11664.
    Berggren, Kajsa
    et al.
    KTH, School of Information and Communication Technology (ICT).
    Rosengren, Michelle
    KTH, School of Information and Communication Technology (ICT).
    Ett digitalt läroverktyg i Android baserat på principer från kognitiv neurovetenskap2016Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Sweden has always been a part of the technological forefront, excelling in innovation and advancing the future of modern technology. However, recently, most of governments in European countries have made an effort of introducing computer science as a part of their national curriculum ­ giving Sweden a run for their money. The Swedish government has made the motion of introducing computer science and programming as a part of the curricuum. Therefore, the project’s aim is to create a user interface for an Android application, where the design and functionality has been based on concepts from cognitive neuroscience.

    Cognitive neuroscience was chosen since it combines both psychology and biology, where the goal is to teach children to learn and retain information, where the chosen methods are based on what stage of development the brain is in. It is quite obvious that a young brain is easily distracted and has a short attention span, which has proven to be a challenge when developing a software that needs to teach information that has to be retained in order for it to be used in future scenarios. Which posed the question ­ How can a software, or more specifically an Android application, teach concepts from computer science and programming in a pedalogical way whilst maintaining the factor of being ‘fun’?

    In order to further investigate the possible answer to the question, data about the user, his actions and behaviour needed to be collected and analyzed. With a qualitative research method, the study designed one prototype and focused on further developing it. Based on the answers, results from interviews and user interaction tests, made the process possible for further investigating, and improving the prototype. The product is based on the comparison of the English and Finnsh governments’ national curriculums, because the Sweden has yet to suggest their goals for the course.

    The analyzed results point to that a game, based on the concepts from cognitive neuroscience, an application can indeed prove effective when it comes to teaching children how to program and learning new topics about computer science. The tests conducted, showed signs that the applied concepts from cognitive neuroscience can be intertwined with an application’s basic functionality, and can be designed accordingly. The study resulted in how to aquire the non­functional requirements that the application needs.

    As future work, the product will be developed so that a wider spectra of users can take advantage of the application. Moreover, the application’s functional requirements ­ what goals the application fulfills ­ needs more research in order to become an effective learning module. Due to that the project is still in its first stage of development, extensive analyses must be made by educators, doctors in cognitive science, and experts about the Swedish school system.

  • 11665.
    Berggren, Karl
    KTH, School of Engineering Sciences (SCI), Physics, Physics of Medical Imaging.
    Spectral image quality and applications in breast tomosynthesis2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    In the 1970s, it was determined that screening mammography is an efficient tool in fighting the increasing number of women dying from breast cancer, and many countries have established screening programs since then. Mammography systems have improved substantially over the years with one of the major advances being the transition from x-ray film to digital x-ray detectors. Following this development, the number of women dying from breast cancer has decreased, but there is still much room for improvement. One technology that is changing the breast imaging landscape is breast tomosynthesis; tomographic imaging with in-plane resolution similar to that of mammography, albeit limited height resolution. Breast tomosynthesis is commonly implemented with flat-panel detectors, but line detectors in a slit-scanning geometry can also be used. The latter configuration allows for more complex detector technologies, such as spectral photon-counting detectors that enable single-shot spectral imaging. The combination of spectral imaging and tomosynthesis opens up for a range of new applications, but the slit scanning geometry, which differs substantially from that of flat-panel tomosynthesis systems, and the factors affecting image quality have not been well understood. This thesis aims at filling this gap. Image quality and the parameters that influence image quality in spectral photon-counting slit-scanning breast tomosynthesis are characterized and analyzed using cascaded-systems modelling and linear image quality metrics. In addition, the thesis goes into characterizing the x-ray properties of breast tissue, an important input parameter for accurate material decomposition of in-vivo tissue. Material decomposition with spectral imaging opens up a range of applications, such as accurate measurement of volumetric breast density and spectral lesion characterization for decision support as part of mammography screening, and contrast-enhanced K-edge imaging for diagnostics. Tomosynthesis combined with material decomposition has the potential to improve these methods further by, for instance, separating lesions or regions of interest from surrounding fibro-glandular tissue in quantitative 3D maps of breast tissue.

  • 11666.
    Berggren, Karl
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Physics of Medical Imaging. Philips Mammography Solutions, 164 40 Kista, Sweden.
    Cederstrom, Bjorn
    Lundqvist, Mats
    Fredenberg, Erik
    Cascaded systems analysis of shift-variant image quality in slit-scanning breast tomosynthesis2018In: Medical PhysicsArticle in journal (Refereed)
  • 11667.
    Berggren, Karl
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Physics of Medical Imaging. Philips Mammorgaphy Solutions.
    Cederström, Björn
    Philips Mammography Solutions.
    Lundqvist, Mats
    Philips Mammography Solutions.
    Fredenberg, Erik
    Philips Research.
    Characterization of photon-counting multislit breast tomosynthesis2018In: Medical Physics, E-ISSN 2473-4209Article in journal (Refereed)
    Abstract [en]

    Purpose: It has been shown that breast tomosynthesis may improve sensitivity and specificity compared to two-dimensional mammography, resulting in increased detection-rate of cancers or lowered call-back rates. The purpose of this study is to characterize a spectral photon-counting multislit breast tomosynthesis system that is able to do single-scan spectral imaging with multiple collimated x-ray beams. The system differs in many aspects compared to conventional tomosynthesis using energyintegrating flat-panel detectors. Methods: The investigated system was a prototype consisting of a dual-threshold photon-counting detector with 21 collimated line detectors scanning across the compressed breast. A review of the system is done in terms of detector, acquisition geometry, and reconstruction methods. Three reconstruction methods were used, simple back-projection, filtered back-projection and an iterative algebraic reconstruction technique. The image quality was evaluated by measuring the modulation transfer-function (MTF), normalized noise-power spectrum, detective quantum-efficiency (DQE), and artifact spread-function (ASF) on reconstructed spectral tomosynthesis images for a total-energy bin (defined by a low-energy threshold calibrated to remove electronic noise) and for a high-energy bin (with a threshold calibrated to split the spectrum in roughly equal parts). Acquisition was performed using a 29 kVp W/Al x-ray spectrum at a 0.24 mGy exposure. Results: The difference in MTF between the two energy bins was negligible, that is, there was no energy dependence on resolution. The MTF dropped to 50% at 1.5 lp/mm to 2.3 lp/mm in the scan direction and 2.4 lp/mm to 3.3 lp/mm in the slit direction, depending on the reconstruction method. The full width at half maximum of the ASF was found to range from 13.8 mm to 18.0 mm for the different reconstruction methods. The zero-frequency DQE of the system was found to be 0.72. The fraction of counts in the high-energy bin was measured to be 59% of the total detected spectrum. Scantimes ranged from 4 s to 16.5 s depending on voltage and current settings. Conclusions: The characterized system generates spectral tomosynthesis images with a dual-energy photon-counting detector. Measurements show a high DQE, enabling high image quality at a low dose, which is beneficial for low-dose applications such as screening. The single-scan spectral images open up for applications such as quantitative material decomposition and contrast-enhanced tomosynthesis. 

  • 11668.
    Berggren, Karl
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Physics of Medical Imaging. Philips Mammography Solutions.
    Cederström, Björn
    Philips Mammography Solutions.
    Lundqvist, Mats
    Philips.
    Fredenberg, Erik
    Philips Research.
    Technical Note: Comparison of first‐ and second‐generation photon‐counting slit‐scanning tomosynthesis systems2018In: Medical PhysicsArticle in journal (Refereed)
    Abstract [en]

    Purpose: Digital breast tomosynthesis (DBT) is an emerging tool for breast-cancer screening and diagnostics. The purpose of this study is to present a second-generation photon-counting slitscanning DBT system and compare it to the first-generation system in terms of geometry and image quality. The study presents the first image-quality measurements on the second-generation system. Method: The geometry of the new system is based on a combined rotational and linear motion, in contrast to a purely rotational scan motion in the first generation. In addition, the calibration routines have been updated. Image quality was measured in the center of the image field in terms of in-slice modulation transfer function (MTF), artifact spread function (ASF), and in-slice detective quantum efficiency (DQE). Images were acquired using a W/Al 29 kVp spectrum at 13 mAs with 2 mm Al additional filtration and reconstructed using simple back-projection. Result: The in-slice 50% MTF was improved in the chest-mammilla direction, going from 3.2 to 3.5 lp/mm, and the zero-frequency DQE increased from 0.71 to 0.77. The MTF and ASF were otherwise found to be on par for the two systems. The new system has reduced in-slice variation of the tomographic angle. Conclusions: The new geometry is less curved, which reduces in-slice tomographic-angle variation, and increases the maximum compression height, making the system accessible for a larger population. The improvements in MTF and DQE were attributed to the updated calibration procedures. We conclude that the second-generation system maintains the key features of the photon-counting system while maintaining or improving image quality and improving the maximum compression height. 

  • 11669.
    Berggren, Karl
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Physics of Medical Imaging. Philips Healthcare, Sweden.
    Danielsson, Mats
    KTH, School of Engineering Sciences (SCI), Physics, Physics of Medical Imaging.
    Fredenberg, Erik
    Philips Healthcare, Sweden.
    Rayleigh imaging in spectral mammography2016In: MEDICAL IMAGING 2016: PHYSICS OF MEDICAL IMAGING, 2016, article id 97830AConference paper (Refereed)
    Abstract [en]

    Spectral imaging is the acquisition of multiple images of an object at different energy spectra. In mammography, dual-energy imaging (spectral imaging with two energy levels) has been investigated for several applications, in particular material decomposition, which allows for quantitative analysis of breast composition and quantitative contrast-enhanced imaging. Material decomposition with dual-energy imaging is based on the assumption that there are two dominant photon interaction effects that determine linear attenuation: the photoelectric effect and Compton scattering. This assumption limits the number of basis materials, i.e. the number of materials that are possible to differentiate between, to two. However, Rayleigh scattering may account for more than 10% of the linear attenuation in the mammography energy range. In this work, we show that a modified version of a scanning multi-slit spectral photon-counting mammography system is able to acquire three images at different spectra and can be used for triple-energy imaging. We further show that triple-energy imaging in combination with the efficient scatter rejection of the system enables measurement of Rayleigh scattering, which adds an additional energy dependency to the linear attenuation and enables material decomposition with three basis materials. Three available basis materials have the potential to improve virtually all applications of spectral imaging.

  • 11670.
    Berggren, Karl
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Physics of Medical Imaging.
    Eriksson, Mikael
    Hall, Per
    Wallis, Matthew
    Fredenberg, Erik
    In-vivo measurement of the effective atomic number of breast skin using spectral mammography2018In: Article in journal (Refereed)
  • 11671.
    Berggren, Karl
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Physics of Medical Imaging. Royal Inst Technol KTH, Dept Phys, Stockholm, Sweden.;Philips Mammog Solut, Kista, Sweden..
    Eriksson, Mikael
    Karolinska Inst, Dept Med Epidemiol & Biostat, Stockholm, Sweden..
    Hall, Per
    Karolinska Inst, Dept Med Epidemiol & Biostat, Stockholm, Sweden.;South Gen Hosp, Dept Oncol, Stockholm, Sweden..
    Walliss, Matthew G.
    Addenbrookes Hosp, Cambridge Breast Unit, Cambridge, England.;Addenbrookes Hosp, NIHR Cambridge Biomed Res Ctr, Cambridge, England..
    Fredenberg, Erik
    Philips Res, Kista, Sweden..
    In vivo measurement of the effective atomic number of breast skin using spectral mammography2018In: Physics in Medicine and Biology, ISSN 0031-9155, E-ISSN 1361-6560, Vol. 63, no 21, article id 215023Article in journal (Refereed)
    Abstract [en]

    X-ray characteristics of body tissues are of crucial importance for developing and optimizing x-ray imaging techniques, in particular for dosimetry and spectral imaging applications. For breast imaging, the most important tissues are fibro-glandular, adipose and skin tissue. Some work has and is being done to better characterize these tissue types, in particular fibro-glandular and adipose tissue. In the case of breast skin, several recent studies have been published on the average skin thickness, but with regards to x-ray attenuation, the only published data, to the knowledge of the authors, is the elemental composition analysis of Hammerstein et al (1979 Radiology 130 485-91). This work presents an overview of breast skin thickness studies and a measurement of the effective atomic number (Z(eff)) of breast skin using spectral mammography. Z(eff), which together with the density forms the attenuation, is used to validate the work by Hammerstein et al, and the dependence of clinical parameters on Z(eff) is explored. Measurements were conducted on the skin edge of spectral mammograms using clinical data from a screening population (n = 709). The weighted average of breast skin thickness reported in studies between 1997 and 2013 was found to be 1.56 +/- 0.28 mm. Mean Z(eff) was found to be 7.365 (95% CI: 7.364,7.366) for normal breast skin and 7.441 (95% CI: 7.440,7.442) for the nipple and areola. Z(eff) of normal breast skin is in agreement with Hammerstein et al, despite the different methods and larger sample size used. A small but significant increase in Z(eff) was found with age, but the increase is too small to be relevant for most applications. We conclude that normal breast skin is well described by a 1.56 mm skin layer and the elemental composition presented by Hammerstein et al (1979 Radiology 130 485-91) and recommend using these characteristics when modelling breast skin.

  • 11672.
    Berggren, Karl
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Physics of Medical Imaging. Philips Healthcare, S-17141 Solna, Sweden.
    Lundqvist, Mats
    Cederstrom, Bjorn
    Danielsson, Mats
    KTH, School of Engineering Sciences (SCI), Physics, Physics of Medical Imaging.
    Fredenberg, Erik
    Physical characterization of photon-counting tomosynthesis2015Conference paper (Refereed)
    Abstract [en]

    Tomosynthesis is emerging as a next generation technology in mammography. Combined with photon-counting detectors with the ability for energy discrimination, a novel modality is enabled - spectral tomosynthesis. Further advantages of photon-counting detectors in the context of tomosynthesis include elimination of electronic noise, efficient scatter rejection (in some geometries) and no lag. Fourier-based linear-systems analysis is a well-established method for optimizing image quality in two-dimensional x-ray systems. The method has been successfully adapted to three-dimensional imaging, including tomosynthesis, but several areas need further investigation. This study focuses on two such areas: 1) Adaption of the methodology to photon-counting detectors, and 2) violation of the shift-invariance and stationarity assumptions in non-cylindrical geometries. We have developed a Fourier-based framework to study the image quality in a photon-counting tomosynthesis system, assuming locally linear, stationary, and shift-invariant system response. The framework includes a cascaded-systems model to propagate the modulation-transfer function (MTF) and noise-power spectrum (NPS) through the system. The model was validated by measurements of the MTF and NPS. High degrees of non-shift invariance and non-stationarity were observed, in particular for the depth resolution as the angle of incidence relative the reconstruction plane varied throughout the imaging volume. The largest effects on image quality in a given point in space were caused by interpolation from the inherent coordinate system of the x-rays to the coordinate system that was used for reconstruction. This study is part of our efforts to fully characterize the spectral tomosynthesis system, we intend to extend the model further to include the detective-quantum efficiency, observer modelling, and spectral effects.

  • 11673.
    Berggren, Karl-Fredrik
    et al.
    Linköping University.
    Brodeur, Doris
    Massachusetts Institute of Technology.
    Crawley, Ed F.
    Massachusetts Institute of Technology.
    Ingemarsson, Ingemar
    Linköping University.
    Litant, William T. G.
    Massachusetts Institute of Technology.
    Östlund, Sören
    KTH, Superseded Departments, Solid Mechanics.
    An International Initiative for Reforming Engineering Education2003In: World Transactions on Engineering and Technology Education, Vol. 2, no 1, p. 49-52Article in journal (Refereed)
  • 11674.
    Berggren, Kersti
    KTH, Superseded Departments, Infrastructure.
    Varsam ombyggnad i ett riksintressant område2002Licentiate thesis, monograph (Other scientific)
  • 11675.
    Berggren Kleja, Dan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Elert, Mark
    Kemakta Konsult AB.
    Gustafsson, Jon Petter
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Jarvis, las
    Markvetenskap, SLU.
    Norrström, Ann-Catrine
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Metallers mobilitet i mark2006Report (Refereed)
    Abstract [sv]

    I rapporten beskrivs nuvarande kunskapsläge när det gäller metallers uppträdande imark. Riskbedömningar för metaller i förorenad mark diskuteras.De flesta metaller binds i viss utsträckning i marken, oftast genom olika ytreaktioner med markens organiska material eller med järn- och aluminiumoxider, ochibland även genom utfällningsreaktioner. I vilken omfattning detta sker beror avfaktorer som t.ex. pH, redoxförhållanden, löst organiskt material (DOC) i markvattnet, samt förekomst av konkurrerande joner. Det är också viktigt att beaktavilka former metallerna förekommer som i markvattnet. Komplexbildning medt.ex. DOC minskar i regel toxiciteten. För att bättre ta hänsyn till markkemiskaförhållanden i riskbedömningen bör geokemiska modeller komma till ökad användning.Metaller lösta i vattnet följer med när vattnet strömmar och kan transporterastill grund- och ytvatten eller tas upp av växter. Hur snabbt detta går beror, förutomkemiska och biologiska processer, även på en rad olika jordegenskaper. Till exempel innehåller vissa jordar s.k. makroporer vilka ger upphov till preferentiellt flöde.Detta innebär att en del av metallerna snabbare kan transporteras genom marken,förbi jordpartiklar där metallerna annars skulle bindas.De olika modeller som används för att beskriva påverkan av markförorening pågrundvatten kan delas in i två grupper: stationära modeller antar att källtermen ärkonstant och tar enbart hänsyn till den utspädning som sker i grundvattnet. Exempel på sådana modeller är den svenska riktvärdesmodellen, JAGG och RBCA. I detvå senare modellerna finns möjlighet att ta hänsyn till nedbrytning av organiskaämnen. Tidsberoende modeller antar en avklingande källterm och en tidsberoendetransport i grundvattnet, exempelvis RISC och TAC-modellen. För beräkning avtransport i grundvattnet tas hänsyn till flödes- och fastläggningsmekanismer somadvektion, dispersion och linjär sorption.Med hjälp av laktester kan man uppskatta den andel av metallföroreningen somär löslig i vatten. Denna information kan sedan användas för att beräkna adsorptionsparametrar (Kd-värden, m.m.) för spridningsmodeller. Laktester kan ibland gemissvisande resultat eftersom de orsakar utspädning av provet, bl.a. blir DOCkoncentrationerna alltför låga. Dessutom bör de inte användas för sulfidjordar.Geokemiska modeller kan användas för att förbättra tolkningen av laktester för attfå till stånd realistiska uppskattningar av Kd-värden.Det finns ett antal spridningsmodeller som kan användas för att bedöma riskenför spridning till grundvatten och ytvatten. De är kraftfulla verktyg som dock ännuinte använts i någon större utsträckning i Sverige. Detta beror på flera orsaker, bl.a.de hydrogeologiska förhållandena i Sverige, behovet av anpassningen av de modeller som är allmänt tillgängliga, svårigheter att ta fram bra dataunderlag samt ensvag tradition i att använda modeller och förstå modellresultat.Ett par angelägna forsknings- och utvecklingsinsatser är att ta fram bättre uppskattningar av metalladsorption i svensk mark, och att anpassa existerande spridningsmodeller för användning i riskbedömningar.

  • 11676. Berggren Kleja, Dan
    et al.
    Svensson, Magnus
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Majdi, Hooshang
    Jansson, Per-Erik
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Langvall, Ola
    Bergkvist, Bo
    Johansson, Maj-Britt
    Weslien, Per
    Lindroth, Anders
    Pools and fluxes of carbon in three Norway spruce ecosystems along a climatic gradient in Sweden.2008In: Biogeochemistry, ISSN 0168-2563, E-ISSN 1573-515X, Vol. 89, no 1, p. 7-25Article in journal (Refereed)
    Abstract [en]

    This paper presents an integrated analysis of organic carbon (C) pools in soils and vegetation, within-ecosystem fluxes and net ecosystem exchange (NEE) in three 40-year old Norway spruce stands along a north-south climatic gradient in Sweden, measured 2001-2004. A process-orientated ecosystem model (CoupModel), previously parameterised on a regional dataset, was used for the analysis. Pools of soil organic carbon (SOC) and tree growth rates were highest at the southernmost site (1.6 and 2.0-fold, respectively). Tree litter production (litterfall and root litter) was also highest in the south, with about half coming from fine roots (< 1 mm) at all sites. However, when the litter input from the forest floor vegetation was included, the difference in total litter input rate between the sites almost disappeared (190-233 g C m(-2) year(-1)). We propose that a higher N deposition and N availability in the south result in a slower turnover of soil organic matter than in the north. This effect seems to overshadow the effect of temperature. At the southern site, 19% of the total litter input to the O horizon was leached to the mineral soil as dissolved organic carbon, while at the two northern sites the corresponding figure was approx. 9%. The CoupModel accurately described general C cycling behaviour in these ecosystems, reproducing the differences between north and south. The simulated changes in SOC pools during the measurement period were small, ranging from -8 g C m(-2) year(-1) in the north to +9 g C m(-2) year(-1) in the south. In contrast, NEE and tree growth measurements at the northernmost site suggest that the soil lost about 90 g C m(-2) year(-1).

  • 11677.
    Berggren, Max
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Industrial Ecology.
    Aerodynamisk optimering av vindkraftverks rotorblad med en genetisk algoritm, BEM-teori, och XFOIL2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This study presents a methodology that enables the annual average power of a wind turbine to be increased by automatically optimizing it’s airfoil, twist and chord dis- tribution. As a part of the study the software SiteOpt has been developed. This software connects the open source software XFOIL with the blade element momen- tum theory. XFOIL gives lift and drag coefficients which enable the blade element momentum theory to predict the power of a wind turbine at different wind and ro- tational speeds. An optimization algorithm of the type genetic algorithms is used to develop a new rotor blade. An academic benchmark case (Unsteady Aerodynamics Experiment Phase III) was selected as a starting point of the optimization because wind tunnel data was available for that campain. With the geometry developed by the genetic algoritm a theoretical increase of 15 % more power could be extracted. However, it has been shown that the model has shortcomings at high wind speeds where the predicted power does not match wind tunnel data. This is thought to be related to that the model assumes a completely rigid blade. In real world applica- tions a rotorblade will bend on higher wind speeds (about 8 m/s). It is therefore concluded that the model in its current form is flawed and that future work should aim to take these effects into account. However, a wind histogram for a specific loca- tion was used in order to calculate the annual average power for the wind turbine. The wind histogram used in this study to obtain the results has it’s wind speeds 81 % before 10 m/s where the model is acceptable. Therefore the results are largely to be considered accurate. 

  • 11678.
    Berggren, Max
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.).
    Wiklund, Johanna
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.), Organization and management.
    Conditions for Collaborative Creativity in Mobile Multi-Locational Work Systems: A managerial perspective on supporting collaborative creativity in a virtualized setting2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The increasingly virtualized work life, brought on by increased demand on flexibility and work- life balance as well as technological development, has changed the way we work. At the same time the need for organizations to be creative in order to compete on the expanding market has grown. This is a fact that increases the need for groups to be creative through collaboration. Hence, this study investigates how collaborative creativity can be created in Mobile Multi-Locational Work Systems, from a managerial point of view.

    The existing theoretical body of knowledge on collaborative creativity and virtual structures, such as Mobile Multi-Locational Work Systems, points to communication as an area of key importance. When further investigating the factor of communication, two sub-areas were identified; Social Factors and Coordination. Moreover the role of leadership in collaborative creativity implies that managers have an important role in creating conditions for collaborative creativity.

    In order to investigate how collaborative creativity can be stimulated in Mobile Multi-Locational Work Systems, managerial perceptions of work within such a system were collected through interviews at our case company, Microsoft AB. The organization had implemented a Mobile Multi- Locational Work Systems called the New World of Work, allowing employees to work flexibly. Results imply that Mobile Multi-Locational Work Systems affect conditions for collaborative creativity in both stimulating and inhibiting manners. The system implementation appears to increase group external communication across organizational boundaries. It likely increases the amount of ideas and knowledge available, which is positive for collaborative creativity. However, handling factors related to communication, social factors and work coordination within work groups appears to be critical in facilitating collaborative creativity as they appear to be affected by the Mobile Multi-Locational Work System implementation. Results indicate that if managers allows freedom with responsibility, provides a clear framework, creates forums for social and work interaction, coaches their employees and acts as role models it is likely that they will stimulate collaborative creativity in their team.

  • 11679.
    Berggren, Nicole
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Randahl Oskarsson, Sun
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Biodrivmedel från alger - En jämförelse av två tänkbara modeller2012Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Today’s industrialized society desperately needs to reduce its dependence on fossil fuels; in order to accomplish this, an enormous amount of time and money is invested in research to develop renewable alternatives. This type of research has led to renewable alternatives, such as biodiesel and bioethanol that are currently being used in the transportation sector.Algae have a long commercial history, mainly being used as food or for the extraction of other high value components such as proteins and pigments. More recently however, algae have also been cultivated for biofuel production. Some species of algae are very rich in oils or carbohydrates, and by extracting these, biofuels such as biodiesel and bioethanol can be produced.This report describes how a system for fuel production from algae could be designed on a fictional island in the Pacific Ocean, ± 10 ⁰ of the equator. The conditions on this island are assumed to be comparable with existing islands in the same area, and data from these islands are therefore used as extensively as possible. The area of the fictional island is 10 km2 and has 100 000 inhabitants, who are assumed to have the same living standards as an average Swede. The objective of this project is to prove that it is possible to create a sustainable production of biofuel, in spite of scarce resources. The goal is to examine if it is profitable, from an economic and energetic point of view, to produce fuel from algae on the fictional island, and to investigate opportunities for expansion and export.The report is based on a comparison of biodiesel production from microalgae and ethanol production from macroalgae. The literature review illustrates the most common, commercially grown algae species, common cultivation methods, and various options for the fuel production processes. The literature review also includes other areas that are relevant for the designing of the models. The case study and models show a suggestion of how the biodiesel and ethanol productions could be designed. Ethanol is derived from the macro-alga Kappaphycus alvarezii, cultured in the sea in pens made of PVC-covered steel wire mesh. Biodiesel production is carried out from the microalgae Nannochloropsis, cultured in a basin made of hypalon plastic and designed as a closed fish cage.The results obtained from the proposed design of the biodiesel production from microalgae, show a negative energy balance on 41,7 MJ per kg derived biodiesel. Furthermore, the calculated minimum price of 154,66 kr/kg was significantly higher than an estimated, competitive price. For the ethanol production from macroalgae, a positive energy balance was achieved, giving 12,74 MJ per kg derived ethanol. However, the estimated minimum price of 576,04 kr/kg is not near a competitive price. It is also concluded that it is not possible to meet estimated fuel needs of the fictional island from the proposed models. To do this, a cropping area of about 13 km2 and 370 km2 is needed for the micro and macroalgae culture, respectively. Furthermore, the opportunities for expansion of the proposed models are considered very limited, since fundamental conditions such as a positive energy balance and an opportunity for a competitive price are not met. The sensitivity analysis however concludes that there are many parameters in the design of the models that are uncertain, and under other conditions it is possible to have both economical and energetic profits from biodiesel production from microalgae.

  • 11680.
    Berggren, Nicole
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Randahl Oskarsson, Sun
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Framtiden sedd i backspegeln: En analys av framtidsscenarier för energisystem från 1970-talet och framåt2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 11681.
    Berggren, Niklas
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology and Design.
    Gustafsson, Henke
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology and Design.
    Dags att vända blad för monarkins fasad: Putsarbeten på Stockholms slott2011Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The restoration work of the Gotland sandstone at the Royal Palace in Stockholm began in spring 2011. In the first stage the sandstone of "norra Logårdsflygelns" facade will be restored. The restoration of the sandstone will cause damage to the plastered surfaces. Before work was started the plaster was in good condition considering its age, although some ballast were washed up on the surface.

    With the damage that will occur, it has since emerged to develop a plaster for patching. The patching plaster that we have developed through this thesis matches the existing plaster in color, texture, ageing and technical characteristics.

    For the production of patching plaster, we have studied the two original recipes used in the polishing of the facade. We have also conducted laboratory experiments with material replaced in the original recipe because they are not still available on the market.

    During the laboratory, we have determined by screening the existing plaster ballast fractions and its distribution. The replacement ballast that we have developed is following the existing ballasts term curves.

    The laboratory sessions resulted in a prescription for 25 kg plaster. This recipe contains precise amounts of binders, ballast and pigments. When the restorations are performed, the polished surface must be treated by brush and water to achieve the right structure. In this thesis we have developed methods for the treatment of the two extremes of the surface.

    We have also presented a plaster that can be used when the complete castle is plasterd. We have not done any lab work with this plaster but we have chosen an existing NHL-plaster. This plaster is working well with the palace’s façade and its construction. We suggest that the uncoloured plaster is painted with an NHL-lime color.

    In this thesis, we have not taken into account the economic aspects of material selections and work methods.

  • 11682.
    Berggren, Oscar
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology and Design.
    Lundgren, Emil
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology and Design.
    Ökad detaljeringsgrad i ByggnadsInformationsModellen: BIM-laboration om virtuell uppregling av gipsväggar som ett sätt att spara resurser2012Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This report aims to answer the question: "Can an increased level of detail in the Building Information Model by virtually constructed framing for drywalls save resources?" The report concerns a BIM laboration conducted in collaboration with NCC in the project Signalfabriken in Sundbyberg. Lindab Revit Tools (LRT) was used to virtually construct framing for drywalls that was added to the building information model of the project. The virtual material was subject to clash detection analysis and then used to generate A3-sheets for use in the production line. The result of this test and the quality of the sheet was discussed by representatives from different parts of the construction process. A revised sheet was formed from this discussion and then approved by NCC. The process was repeated to find the most efficient process and the experiences from this led to these answers for the original question: Yes, when only complex areas are modeledYes, if all areas are modeled and LRT is improvedNo, if LRT is used to virtually construct all dry walls in the project Besides these answers the report includes: a suggestion for a sheet optimized for use in the production line, a list of improvements for LRT and a description of the process in full for a curtain area together with the details of how much time resources were spent. This report is directed towards construction engineers and readers with equivalent level of knowledge.

  • 11683.
    Berggren, Patrik
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Design and Bridges.
    Dimensioneringshjälp vid konstruktion av kolfiberförstärkning på enkelspänd bjälklagsplatta i ett fack2009Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 11684.
    BERGGREN, PATRIK
    KTH, School of Computer Science and Communication (CSC).
    Efficient features for representing hand shape in images: By using linear projections in the HOG feature space2014Independent thesis Advanced level (degree of Master (Two Years)), 20 HE creditsStudent thesis
    Abstract [en]

    This thesis explores hand pose estimation, which means mapping a 2D imageto a hand pose. Hand pose estimation has many promising applications suchas hand sign recognition, robotic learning by demonstration, and human computer interaction in general. To do the estimation, image features are extracted from the image and a mapping to the space of hand poses is the nconstructed. Ideally the mapping from image features to pose space would be one-to-one, but in reality it is rather a many-to-many mapping leadingto ambiguities. This is due to the image feature not capturing the actualpose, but the form of the 2D projection of the hand. Hands may also occludeparts of itself which also leads to ambiguities. This thesis explores ways in which to improve the commonly used image feature HOG (Histogram of Oriented Gradients), by capturing the HOG subspace used by hand images, to obtain a feature whose mapping to pose space is more well-behaved than that of the HOG feature. The new feature is computed as projection on anddistances to lines in HOG space. The new feature’s performance is tested against the HOG feature using nearest neighbour (NN) regression and the results show that the new feature does not yet perform as well as the HOG feature. Nevertheless, the conclusion is that the new feature, called MPDD,for Multiple Projection and Distance Dimensions, does indeed capture the most relevant information in HOG, but fail to use it as well as the HOG does with the current construction method. However, constructing the MPDD in a slightly different way could potentially lead to improvements and so future research could still be of interest.

  • 11685.
    BERGGREN, PATRIK
    KTH, School of Computer Science and Communication (CSC).
    Efficient features for representing hand shape inimages: By using linear projections in the HOG feature space2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis explores hand pose estimation, which means mapping a 2D image to a hand pose. Hand pose estimation has many promising applications such as hand sign recognition, robotic learning by demonstration, and human-computer-interaction in general. To do the estimation, image features are extracted from the image and a mapping to the space of hand poses is then constructed. Ideally the mapping from image features to pose space would be one-to-one, but in reality it is rather a many-to-many mapping leading to ambiguities. This is due to the image feature not capturing the actualpose, but the form of the 2D projection of the hand. Hands may also occludeparts of itself which also leads to ambiguities. This thesis explores waysin which to improve the commonly used image feature HOG (Histogram of Oriented Gradients), by capturing the HOG subspace used by hand images,to obtain a feature whose mapping to pose space is more well-behaved than that of the HOG feature. The new feature is computed as projection on and distances to lines in HOG space. The new feature’s performance is tested against the HOG feature using nearest neighbour (NN) regression and the results show that the new feature does not yet perform as well as the HOG feature. Never the less, the conclusion is that the new feature, called MPDD, for Multiple Projection and Distance Dimensions, does indeed capture the most relevant information in HOG, but fail to use it as well as the HOG does with the current construction method. However, constructing the MPDD ina slightly different way could potentially lead to improvements and so future research could still be of interest.

  • 11686.
    Berggren, Patrik
    et al.
    KTH, School of Computer Science and Communication (CSC).
    Nilsson, David
    KTH, School of Computer Science and Communication (CSC).
    A study of Sudoku Solving Algorithms.2012Independent thesis Advanced level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In this bachelor thesis three different Sudoku solving algorithms are studied. The study is primarily concerned with solving ability, but also includes the following: difficulty rating, puzzle generation ability, and suitability for parallelizing. These aspects are studied for individual algorithms but are also compared between the different algorithms. The evaluated algorithms are backtrack, rule-based and Boltzmann machines. Measurements are carried out by measuring the solving time on a database of 17-clue puzzles, with easier versions used for the Boltzmann machine. Results are presented as solving time distributions for every algorithm, but relations between the algorithms are also shown. We conclude that the rule-based algorithm is by far the most efficient algorithm when it comes to solving Sudoku puzzles. It is also shown that some correlation in difficulty rating exists between the backtrack and rule-based algorithms. Parallelization is applicable to all algorithms to a varying extent, with clear implementations for search-based solutions. Generation is shown to be suitable to implement using deterministic algorithms such as backtrack and rule-based.

  • 11687. Berggren, R.
    et al.
    Molin, U.
    Berthold, F.
    Lennholm, H.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH). KTH, Fibre- and Polymer technology.
    Lindström, M.
    Alkaline degradation of birch and spruce: Influence of degradation conditions on molecular mass distributions and fibre strength2002In: Carbohydrate Polymers, Vol. 51, no 3, p. 255-264Article in journal (Refereed)
  • 11688. Berggren, R.
    et al.
    Molin, U.
    Berthold, F.
    Lennholm, H.
    Lindström, Mikael
    Alkaline degradation of birch and spruce: influence of degradation conditions on molecular mass distributions and fibre strength2003In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 51, no 3, p. 255-264Article in journal (Refereed)
    Abstract [en]

    The alkaline degradation of birch and Norway spruce during kraft pulping was studied on a laboratory scale by two degradation strategies, by varying the pulping time using the same initial alkali level and by varying the initial alkali concentration using a constant time. The degradation at the molecular level was monitored by determining the carbohydrate composition, intrinsic viscosity and-molecular mass distribution (MMD). The influence of the degradation on fibre strength was studied as zero-span tensile index. The alkaline degradation was to a large extent homogeneous on a molecular level. However, some significant differences in degradation patterns were found. In the case of birch, the two different degradation strategies (increased alkali level and increased pulping time) caused differences in MMD and fibre strength (comparisons made at a given intrinsic viscosity or M-w). For spruce pulps, the decrease in fibre strength and the shift in MMD were the same in both series, regardless of degradation strategy.

  • 11689.
    Berggren, Ralf
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Hydling, Johnnie
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Laserskärning i Sverige: – tekniken, marknaden och hur de utvecklas2010Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Laser for material processing possesses a number of advantages which mean that it has been and will be an important component for a wide range of industries' future development. Cutting materials processing is the dominant use of laser technology and has revolutionized the manufacturing industry. The aim of this thesis is to describe the principles of metal cutting by laser, how laser cutting is applied in practice and to identify how Swedish companies are using laser cutting. For the theoretical and technical description of laser cutting literature studies are the primary source of information. The empirical basis for the mapping of the Swedish industry for laser cutting is grounded on a survey; this includes Swedish companies that use laser cutting in their production. The companies were asked about their own sales and the development of their customer base, how laser cutting is used in their production and how they see the future of the industry.The study indicates a long term trend of increased sales for companies in the industry. Companies with a turnover below 10 MSEK has steadily declined over the last twenty years, while businesses with a turnover between 11-40 MSEK and more than 40 MSEK have increased. The surveyed firms report that national as well as international competition has become tougher and the product portfolio today contains more advanced products than before. Laser cutting has several advantages over competing cutting methods; the key is that a wide range of materials can be processed with high surface quality of the cut and sharp edges. In addition, advanced geometries with high precision can be cut. An overwhelming disadvantage is high cost, and operating costs. A company looking to invest in a plant for laser cutting should consider numerous aspects but mainly: specifications for the product, the conditions for implementation of the technology and installation of equipment and staff knowledge and skills. In the Swedish market for laser cutting, a clear trend in how producers alter their activity has been observed. The product portfolio will be broader and the products are becoming more sophisticated in terms of geometry and accuracy. The number of customers is increasing, thereby reducing dependence on any single industry, customer or product.

  • 11690.
    Berggren, Rickard
    KTH, Superseded Departments, Fibre and Polymer Technology.
    Cellulose degradation in pulp fibers studied as changes in molar mass distributions2003Doctoral thesis, comprehensive summary (Other scientific)
    Abstract [en]

    In this thesis, size-exclusion chromatography (SEC) of woodpolymers dissolved in lithium chloride/N,N-dimethylacetamide(LiCl/DMAc) has been used to characterize the molar massdistributions (MMD) of wood polymers in pulp fibers afterchemical degradation.

    Characterization of birch kraft pulps subjected to ozonedegradation and acid hydrolysis, respectively, rendereddifferent changes in the MMD. Ozone degradation resulted inlarge redistributions of the original MMD, observed as thedevelopment of a distinct fraction of cellulose withintermediate molar mass. Acid hydrolysis resulted in minorchanges of the original MMD compared to ozonation. Fiberssubjected to acid hydrolysis were considerably weaker thanozonated fibers. These results indicated that there aredifferences in how the two chemicals degrade the fiber.

    The solubility of softwood kraft pulp fibers was enhanced byderivatization of the fiber polymers with ethyl-isocyanateduring simultaneous dissolution in LiCl/DMAc. Thederivatization made it possible to achieve reliable estimationsof the MMD, and hence molar masses, of softwood kraft pulps.The derivatization procedure made it possible to dissolve 90 %of softwood kraft pulps with kappa numbers over 50.

    Severe alkaline degradation of birch and Norway spruce woodchips was studied both by varying the pulping time and byvarying the initial alkali concentration. Differences werefound in the MMD of the two fiber types, and the alkalinedegradation was found to affect polymers in the entire MMD.

    Multi-angular laser light scattering (MALLS) was used as adetection technique with SEC on cellulosic samples. The MMD andaverage molar masses obtained through directstandardcalibration with commercial standards were compared with MMDand molar masses as obtained by MALLS-detection. Largediscrepancies were found, and two methods of correcting forthese discrepancies were developed.

    Theoretical simulations of polymer degradation wereperformed. Random, or homogeneous degradation was used as amodel for alkaline cellulose chain scission, and a resemblancewith experimental data was observed. End-wise depolymerizationof cellulose was also simulated and the results are discussedin the light of experimentally observed MMD.

    Keywords:cellulose, kraft pulp, birch, spruce,ozonation, acid hydrolysis, degradation, MMD, sizeexclusionchromatography, light scattering, molar mass, chainscission

  • 11691.
    Berggren, Robert
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Nielsen, Timmy
    KTH, School of Electrical Engineering and Computer Science (EECS).
    Investigating the Reliability of Known University Course Timetabling Problem Solving Algorithms with Updated Constraints2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Scheduling lectures, exams, seminars etc. for a university turns out to be a harder task than what it seems to be at first glance. This problem is known as the University Course Timetabling Problem (UCTP). The UCTP has been hosted for a number of competitions throughout the years by an organization called Practice and Theory of Automated Timetabling (PATAT). Because of these competitions, the problem has been given a standard description and set of constraints as well as standard problem instances for easier comparison of research and work on the subject. However, setting a standard like this have a major drawback; no variety is introduced since new research for finding the greatest method to solve the UCTP is forced to focus on a specific set of constraints, and algorithms developed will only be optimized with these constraints in consideration.

    In this research we compared five well known UCTP algorithms with the standard set of constraints to a different set of constraints. The comparisons showed a difference in the rank of performance between the algorithms when some constraints were changed to fit a certain need. The differences were not great but big enough to state that previous research declaring what algorithms are best for the UCTP problem cannot be relied upon unless you use close to identical sets of constraints. If the goal is to find the best algorithm for a new set of constraints then one should not rely on a single previously defined great algorithm but instead take two or three of the top performing ones for the greatest chance of finding the most optimized solution possible.

  • 11692.
    Berggren, Susanna
    et al.
    KTH, School of Computer Science and Communication (CSC).
    Hanafi, Donna
    KTH, School of Computer Science and Communication (CSC).
    "iPad – för nöjes skull" – En studie över användarvanor på iPad.2011Independent thesis Advanced level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    S U S A N N A B E R G G R E N a n d D O N N A H A N A F I

    "iPad - The Consumerator" A study regarding iPad usage

    BACHELOR THESIS STOCKHOLM, SWEDEN

    ABSTRACT

    This Bachelor thesis' objective is to examine and analyse when and how the iPad is being used in Sweden. The study also looks closer at on which occasions the iPad replace other mobile devices. The main problem formulation is as follows: "During which fields of application has the iPad replaced the laptop and the smart phone?" The thesis will also look into if the iPad has brought any new user habits.

    Apple launched their computer tablet iPad in April 2010. The company was alone on the market with the new generation for a long time, which in part explains their hold of the tablet market. Several companies presented their own version of the computer tablet during the following year. Because of the iPad market leader position on the Swedish tablet market during the time this thesis was written, it is focused entirely on the iPad and its usage.

    The chosen methodology is a combination of a quantitative and a qualitative method. The former included an online survey with 894 respondents who answered 35 questions. The qualitative method was carried through by eight iPad users who documented their iPad usage during three days. This in order to get a more elaborated look into the actual iPad usage in Sweden.

    The online survey showed that the iPad is being used around 16 hours per week and 82% of the respondents answered that they use their iPad several times per day. The main usage occurs between 6 p.m. and midnight. The study also shows that over 20% of the respondents has paid over 200 SEK for an application for the iPad.

    The thesis presents the reasons to why, when and how the respondents rather use their iPad instead of their laptop, which is when they browse the web, e-mail, watch videos, read or play games. The size and mobility of the iPad as well as the fact that it is faster to start than the laptop also has a major affect to why the users considers the iPad to be more flexible and accessible than the laptop during different locations. The iPad has according to our study not replaced the laptop.

    The iPad also had hardware and software limitations which could force the user during specific occasions to use the laptop instead of the iPad. The study has clearly exhibited an attitude trend towards the laptop since the iPad was launched. The iPad is for consuming and the laptop is for producing.

    Susanna Berggren och Donna Hanafi

  • 11693.
    Berggren, Tomas
    et al.
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.).
    Duits, Maurice
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.).
    Mesoscopic Fluctuations for the Thinned Circular Unitary Ensemble2017In: Mathematical physics, analysis and geometry, ISSN 1385-0172, E-ISSN 1572-9656, Vol. 20, no 3, article id 19Article in journal (Refereed)
    Abstract [en]

    In this paper we study the asymptotic behavior of mesoscopic fluctuations for the thinned Circular Unitary Ensemble. The effect of thinning is that the eigenvalues start to decorrelate. The decorrelation is stronger on the larger scales than on the smaller scales. We investigate this behavior by studying mesoscopic linear statistics. There are two regimes depending on the scale parameter and the thinning parameter. In one regime we obtain a CLT of a classical type and in the other regime we retrieve the CLT for CUE. The two regimes are separated by a critical line. On the critical line the limiting fluctuations are no longer Gaussian, but described by infinitely divisible laws. We argue that this transition phenomenon is universal by showing that the same transition and their laws appear for fluctuations of the thinned sine process in a growing box. The proofs are based on a Riemann-Hilbert problem for integrable operators.

  • 11694.
    Berggren, Ulf
    KTH, Superseded Departments, Numerical Analysis and Computer Science, NADA.
    Pappersmodellen som utgångspunkt för utformning av skrivsamar- betsverktyg1999Licentiate thesis, monograph (Other scientific)
  • 11695.
    Berggrén, Erik
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Lunqe, Edward
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Byggfuktens inverkan på energiförbrukning: En studie i energiförluster på grund av byggfukt2015Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Energy efficiency and low energy houses are today important factors within the building sector. What’s often forgotten, and with little or no research available, is how building moisture affect energy consumption. 

    The intention of the thesis is to increase the knowledge of building moistures consequence’s by investigating how large the energy is to dehydrate concrete structures and also to investigate if it should be taken in account by environmental certification when buildings are certified.

    All material and medium strives to be in moisture equilibrium with its environment. For building materials to dehydrate into equilibrium with its environment evaporation is required. Because evaporation makes the ambient temperature lower the energy consumption for heating increases.

    In the thesis the moisture calculation software’s KFX03 and WUFI Pro 5.3 are used to calculate the water quantity of dehydration and when it occurs in concrete structures. A fact sheet was programmed, in Excel, for fast and simple energy calculations of dehydration in a building.

    To estimate the quantity of heated concrete in new buildings three newly produced buildings where studied. The result shows that the energy for dehydrations increased a buildings heating by approximately 5 %, correspondent to roughly 2.5 years of consumption.

    The work indicates that building moisture has a relatively high impact on a buildings heating, when taking the different condition during construction and living in consideration. Therefore the current environment and energy certification systems should in greater regards focus on energy consumption during construction.

    To be able to better answer in which extent the drying of building moisture affects energy consumption comparisons should be done in concrete with different water-cement ratio and energy calculation to estimate energy losses during construction. Thus to answer how big effect a buildings construction phase has on the environment and thereby how big significance this phase should have on environment certifications. 

  • 11696.
    Berggrén, Rasmus
    KTH, School of Computer Science and Communication (CSC).
    In pursuit of consumer-accessible augmented virtuality2017Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This project is an examination of the possibility of using existing software to develop Virtual Reality (VR) software that includes key aspects of objects in a user’s surroundings into a virtual environment, producing Augmented Virtuality (AV). A defining limitation is the requirement that the software be consumer-accessible, meaning it needs run on a common smartphone with no additional equipment. Two related AV concepts were considered: shape reconstruction and positional tracking. Two categories of techniques were considered for taking the measurements of reality necessary to achieve those AV concepts using only a monocular RGB camera as sensor: monocular visual SLAM (mvSLAM) and Structure from Motion (SfM). Two lists of requirements were constructed, formalising the notions of AV and consumer-accessibility. A search process was then conducted, where existing software packages were evaluated for their suitability to be included in a piece of software fulfilling all requirements. The evaluations of SfM systems were made in combination with Multi-View Stereo (MVS) systems – a necessary complement for achieving visible shape reconstruction using a system that outputs point clouds. After thoroughly evaluating a variety of software, it was concluded that consumer-accessible AV can not currently be achieved by combining existing packages, due to several issues. While future hardware performance increases and new software implementations would solve complexity and availability issues, some inaccuracy and usability issues are inherent to the limitation of using a monocular camera. 

  • 11697.
    Berggrén, Rasmus
    et al.
    KTH, School of Computer Science and Communication (CSC).
    Sätterkvist, Arvid
    KTH, School of Computer Science and Communication (CSC).
    Självkvantifiering och påverkan av omdöme vid sociala respektive vetenskapligt grundade jämförelser2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    "Quantified self" services are popular and often contains features for comparing performances between users. When a comparison culture arises, there is a risk that users assess their performances based on the norms that form in a certain circle ("the norms"). This can be contrasted with assessing performances based on scientifically motivated recommendations ("the recommendations"). We wanted to find out how users’ assessments are affected by the two grounds for comparison. 

    We focused on step-counting, which is a simple form of self-quantification. We let 20 people use a pedometer for a week’s time. They then answered a survey, where they got to see how they had performed (average steps/day) and got to assess their performances on a nine-step scale. The survey had 3 steps: In the first step there were no ground for comparison; in the second one there was a diagram for comparing against the norm (forged data); in the third one there was a diagram for comparing against the recommendation (forged data). The participants were split up into four groups: A (+/+), B (+/-), C (-/+), D (-/-)*.

    The results were that both the norm and the recommendation affected the users’ assessments and that the norm had the biggest impact. 69 % (11/16) changed their assessments after having seen the norm and the difference in assessment was on average 1.1. Here, participants were more inclined to higher their assessment than to lower it. In groups B (+/-) and C (-/+), that got to see a recommendation that contradicted the norm, 63 % (5/8) changed their assessments after having seen the recommendation and the difference was on average 1.0. The recommendation largely affected the assessment in the opposite direction of the norm. 

    Based on our results, we would recommend including not only comparison features, but also scientific recommendations, in quantified self services. However, the reliability of our results is low, since the participants were few and came from a very specific group. Our work mainly contributes a well-thought-out methodology that can be developed further. 

    * The symbol before the slash indicates how the group was placed in the forged diagrams compared to the norm and the symbol after how the group was placed compared to the recommendation. Example given, (+/-) means "above the norm, below the recommendation".

  • 11698.
    Bergh, Alexander
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology and Design.
    Pettersson, Erik
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology and Design.
    Utveckling av fastigheten Hydro: Framtagning av förslagshandlingar2013Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Sölvesborg is a city under expansion, people are attracted by a rural idyll close to the sea and the municipality's goal is to increase the population from 16,000 to 20,000 until year 2020. The municipality owns the property Hydro which is located in the central parts of Sölvesborg adjacent to the train station. Today the property Hydro is used as a parking space, the municipality is interested to change the property. They want to make it to a new central hub in Sölvesborg, connecting the railway station and extend the center strip. Our work is to create concept drawings for the property Hydro, These concept drawings are based on analyzes regarding the context of the city and the city’s citizens. This has resulted in a building that has a larger commercial area in the ground floor and above the ground floor are ten floors with four apartments on each floor.

    The guiding principle for the design has been to try to create a new landmark for Sölvesborg, bringing in the modern architecture on a larger scale in the old small scale society in a natural way.

  • 11699.
    Bergh, Cathrine
    KTH, School of Engineering Sciences (SCI), Physics.
    A Water Droplet Model as Boundary Condition for Molecular Dynamics Simulations of Solvated Systems2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 11700.
    Bergh, Cathrine
    KTH, School of Engineering Sciences (SCI), Theoretical Physics.
    Modeling of Conformational Transitions in Membrane Proteins with Coarse-Grained Methods2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Understanding the dynamics of proteins is crucial in order to understand life on a molecular level. In this Bachelor’s thesis large scale motions of the membrane protein SERCA has been investigated with coarse-grained methods. The goal was to find certain places in the structure where mutations could alter and affect the functionality of the protein, possibly leading to disease. The protein was modeled with an elastic network model and simulated with Langevin dynamics. Data from the simulations was used to calculate all the places were formation of stabilizing salt bridges were possible and these were then compared with mutations found in real cancerous cells. Promising results were obtained but need to be investigated further with more sophisticated methods before any conclusions can be drawn regarding their significance for the protein functionality. Likewise, the use of elastic network models together with Langevin dynamics showed to be a good alternative to sample large conformational changes in proteins.

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