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  • 121151.
    Åslund, Johan
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Release rates and environmental impact of zinc-nickel coatings in the automotive industry2006Independent thesis Basic level (professional degree), 20 points / 30 hpStudent thesis
    Abstract [en]

    At present the automotive industry is due to an EU directive, replacing hexavalent chrome on vehicles. This is an extensive job as hexavalent chrome is used all over the vehicle and to large extent on fasteners (screws, nuts, rivets etc.). Chrome (VI) is used as a passivating layer on mainly zinc-iron. When replacing the hexavalent chrome with a chrome (VI) free product, the passivating properties are reduced. One of the alternatives is to replace the zinc-iron coating with a zinc-nickel coating. This coating shows great promise from the corrosion resistance point of view. Zinc-nickel is a cathodically protecting coating, and will in principle dissolve to protect the substrate from corrosion. It is therefore important to understand how, and at what rates nickel is released from zinc-nickel coatings when exposed to a chloride-rich automotive environment. The potential environmental impact of nickel needs to be evaluated before Scania can introduce this alternative as corrosion protection. Tests by Scania have previously shown that contact allergy is not an issue for zinc-nickel coatings with Cr (III) passivation.

    Nickel release rates corresponding to 0,12 mg m-2yr-1 for zinc-15 % nickel coatings at a pH of 4,2 were determined from an accelerated corrosion test. Based on these values, less than 1 kg of nickel per year would be released from the Scania rolling stock if Scania were to introduce zinc-nickel coatings preferably on fasteners. This value is low compared to other sources of nickel release. In order to evaluate the toxicity of the released nickel, information about the chemical speciation, i.e. chemical forms, is needed.

    Total or dissolved metal are not good predictors of ecotoxicity of metals. Chemical speciation and bioavailability must be incorporated in toxicity testing. Total or dissolved metal may be used as a worst case approximation.

  • 121152.
    Åslund, Johan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Welding Technology. KTH, Centres, XPRES, Excellence in production research. Scania CV, Stockholm, Sweden.
    Melander, Arne
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Welding Technology. KTH, Centres, XPRES, Excellence in production research. Swerea KIMAB, Stockholm, Sweden.
    Johansson, Krister
    Scania CV, Stockholm, Sweden.
    Haglund, Sven
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Welding Technology. KTH, Centres, XPRES, Excellence in production research. Swerea KIMAB, Stockholm, Sweden.
    Hosseini, Seyed B.
    Swerea IVF, Stockholm, Sweden.
    Influence of tempering on contact fatigue2009In: New challenges in heat treatment and surface engineering, conference in honour of Prof Božidar Liščić, Dubrovnik, Cavtat, Croatia 9-12 June 2009, 2009, p. 87-94Conference paper (Refereed)
    Abstract [en]

    Most components are tempered after heat treatment operations such as case hardening orinduction hardening. The common opinion is that the martensitic structure after heat treatmentis too brittle and tempering is necessary to increase toughness.

    Tempering is an additional operation which leads to increased costs by energy, handling,and investments. Eliminating tempering from the heat treatment process leads to increasedproductivity, energy savings, and lowered environmental impact.

    Two carburised steels, Ovako 253 and 20NiCrMo2 (AISI 8620, SS2506), were tested forcontact fatigue resistance in a roller to roller rig. The tested samples were characterised withrespect to amount of fatigue damage, residual stress, amount of retained austenite andhardness. The objective was to determine if tempering is always necessary after a heattreatment operation.

    The contact fatigue tests show that tempering results in lower contact fatigue resistance.

  • 121153.
    Åslund, Johannes
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Engineering and Bridges.
    Vridning av stabiliserande torn av lådtvärsnitt med asymmetriska håltagningar i höga   byggnader2004Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 121154. Åslund, M.
    et al.
    Cederström, Björn
    KTH, Superseded Departments, Physics.
    Lundqvist, M.
    Danielsson, Mats
    KTH, Superseded Departments, Physics.
    Scatter rejection in scanned multi-slit digital mammography2004In: Proceedings of SPIE - The International Society for Optical Engineering, 2004, no 1, p. 478-487Conference paper (Refereed)
    Abstract [en]

    Measurements and Monte Carlo simulations were used to investigate the scatter properties of a scanned multi-slit digital mammography system. Scatter to primary ratio (S/P) in the center of the image field was calculated for different thickness of breast equivalent material and different tube potentials. The simulated model also varied the angular acceptance, the number of slits and the distance between the slits of a dedicated scatter rejection device. In addition to the expected scatter from the breast equivalent material, scatter within the detector contributes to the S/P-ratio. The main part of the scatter is identified as coming from this process. Measured total 5/P-ratios below 3% are reported for breast range 3-8 cm. The scatter-DQE is used as figure-of-merit for comparison to other imaging geometries and scatter rejection schemes.

  • 121155.
    Åslund, Magnus
    KTH, School of Engineering Sciences (SCI), Physics.
    Digital Mammography with a Photon Counting Detector in a Scanned Multislit Geometry2007Doctoral thesis, comprehensive summary (Other scientific)
    Abstract [en]

    Mammography screening aims to reduce the number of breast cancer deaths by early detection of the disease, which is one of the leading causes of deaths for middle aged women in the western world. The risk from the x-ray radiation in mammography is relatively low but still a factor in the benefit-risk ratio of screening. The characterization and optimization of a digital mammography system is presented in this thesis. The investigated system is shown to be highly dose efficient by employing a photon counting detector in a scanning multislit geometry.

    A novel automatic exposure control (AEC) is proposed and validated in clinical practise. The AEC uses the leading detector edge to measure the transmission of the breast. The exposure is modulated by altering the scan velocity during the scan. A W-Al anode-filter combination is proposed.

    The characterization of the photon counting detector is performed using the detective quantum efficiency. The effect of the photon counting detector and the multislit geometry on the measurement method is studied in detail. It is shown that the detector has a zero-frequency DQE of over 70\% and that it is quantum limited even at very low exposures.

    Efficient rejection of image-degrading secondary radiation is fundamental for a dose efficient system. The efficiency of the scatter rejection techniques currently used are quantified and compared to the multislit geometry.

    A system performance metric with its foundation in statistical decision theory is discussed. It is argued that a photon counting multislit system can operate at approximately half the dose compared to several other digital mammography techniques.

  • 121156.
    Åslund, Magnus
    et al.
    KTH, School of Engineering Sciences (SCI), Physics.
    Cederström, Björn
    KTH, School of Engineering Sciences (SCI), Physics.
    Lundqvist, M
    Danielsson, M
    Optimized AEC for scanning digital mammography based on local variation of scan velocity2005In: Medical Imaging 2005: Physics of Medical Imaging, Pts 1 and 2 / [ed] Flynn, MJ, BELLINGHAM: SPIE-INT SOC OPTICAL ENGINEERING , 2005, Vol. 5745, p. 468-477Conference paper (Refereed)
    Abstract [en]

    In mammography, there is an optimal photon energy and current time product that produce the required image quality at the minimal dose. The task of an automatic exposure control (AEC), in full field digital mammography (FFDM) is to minimize the dose by using optimized exposure settings. Each point in a mammogram has different radiological thickness. A conventional AEC samples the thickness in some regions to set the current time product and possibly also the beam quality. We define an ideal AEC as one that optimizes the beam quality and exposure in each point to produce a constant contrast-to-noise ratio (CNR) of structures of interest throughout the image. This paper presents the results from a theoretical evaluation of an AEC proposed for a scanning photon-counting FFDM system. The geometry enables the AEC to use information from the leading detector line to adjust the scan velocity during the scan. Thus, the irradiation can be better optimized in the scanning-direction as compared to a conventional AEC. The scan time is further reduced by increased velocity over sections that contain no tissue. The results are quantified in terms of reduction of entrance dose and scan time. The presented AEC is compared to an ideal AEC, a conventional AEC and is also benchmarked against an ideal regulator. The effect of the detector width is evaluated. Compared to a conventional AEC, both evaluated on a set of 266 mammograms, the ideal AEC would reduce the entrance dose by 39% on average while the proposed AEC for scanning systems reduces the entrance dose by 10-20% and scan-time by 25-32% on average, depending on detector width.

  • 121157.
    Åslund, Magnus
    et al.
    KTH, School of Engineering Sciences (SCI), Physics.
    Cederström, Björn
    KTH, School of Engineering Sciences (SCI), Physics.
    Lundqvist, Mats
    KTH, School of Engineering Sciences (SCI), Physics.
    Danielsson, Mats
    KTH, School of Engineering Sciences (SCI), Physics.
    AEC for scanning digital mammography based on variation of scan velocity2005In: Medical physics (Lancaster), ISSN 0094-2405, Vol. 32, no 11, p. 3367-3374Article in journal (Refereed)
    Abstract [en]

    A theoretical evaluation of nonuniform x-ray field distributions in mammography was conducted. An automatic exposure control (AEC) is proposed for a scanning full field digital mammography system. It uses information from the leading part of the detector to vary the scan velocity dynamically, thus creating a nonuniform x-ray field in the scan direction. Nonuniform radiation fields were also created by numerically optimizing the scan velocity profile to each breast's transmission distribution, with constraints on velocity and acceleration. The goal of the proposed AEC is to produce constant pixel signal-to-noise ratio throughout the image. The target pixel SNR for each image could be set based on the breast thickness, breast composition, and the beam quality as to achieve the same contrast-to-noise ratio between images for structures of interest. The results are quantified in terms of reduction in entrance surface air kerma (ESAK) and scan time relative to a uniform x-ray field. The theoretical evaluation was performed on a set of 266 mammograms. The performance of the different methods to create nonuniform fields decreased with increased detector width, from 18% to 11% in terms of ESAK reduction and from 30% to 25% in terms of scan time reduction for the proposed AEC and detector widths from 10 to 60 mm. Some correlation was found between compressed breast thickness and the projected breast area onto the image field. This translated into an increase of the ESAK and decrease of the scan time reduction with breast thickness. Ideally a nonuniform field in two dimensions could reduce the entrance dose by 39% on average, whereas a field nonuniform in only the scanning dimension ideally yields a 20% reduction. A benefit with the proposed AEC is that the risk of underexposing the densest region of the breast can be virtually eliminated.

  • 121158.
    Åslund, Magnus
    et al.
    KTH, School of Engineering Sciences (SCI), Physics.
    Cederström, Björn
    KTH, School of Engineering Sciences (SCI), Physics.
    Lundqvist, Mats
    KTH, School of Engineering Sciences (SCI), Physics.
    Danielsson, Mats
    KTH, School of Engineering Sciences (SCI), Physics.
    Evaluation of an AEC system for scanning photon counting mammography based on variation of scan velocityIn: Medical physics (Lancaster), ISSN 0094-2405Article in journal (Other academic)
  • 121159.
    Åslund, Magnus
    et al.
    KTH, School of Engineering Sciences (SCI), Physics.
    Cederström, Björn
    KTH, School of Engineering Sciences (SCI), Physics.
    Lundqvist, Mats
    Danielsson, Mats
    KTH, School of Engineering Sciences (SCI), Physics.
    Optimization of operating conditions in photon counting multi-slit mammography based on Si-strip detectors - art. no. 61420A2006In: Medical Imaging 2006: Physics of Medical Imaging, Pts 1-3 / [ed] Flynn, MJ; Hsieh, J, 2006, Vol. 6142, p. A1420-A1420Conference paper (Refereed)
    Abstract [en]

    Measurements and simulations of the signal-difference-to-noise ratio (SDNR) and average glandular dose (AGD) have been performed on a photon counting full-field digital mammography system to determine the optimal operating conditions. Several beam qualities were experimentally evaluated by using different combinations of tube voltage, added filters and thickness of BR12 with a tungsten target x-ray tube. The SDNR and AGD were also calculated theoretically for an extended number of operating conditions and a more accurate breast model. As figure of merit for each operating condition, a spectral quantum efficiency (SQE) was calculated as the polychromatic SDNR squared over the optimal monochromatic SDNR squared at the same AGD. The theoretical model agreed within 4% relative the measured SDNR throughout the evaluated breast thickness (30-70 mm) and tube voltage range (26-38 kV). The optimization was performed with a constant SDNR-rate as compared to using a fixed filter thickness. The optimal combinations of tube voltage-filter material were: 32 kV-Ag, 34 kV-Cd, 36 kV-Sn for a breast thickness of 30, 50 and 70 mm respectively. These K-edge filter materials increased the SQE by less than 4% compared to the optimal Al filtration.

  • 121160.
    Åslund, Magnus
    et al.
    KTH, School of Engineering Sciences (SCI), Physics.
    Cederström, Björn
    KTH, School of Engineering Sciences (SCI), Physics.
    Lundqvist, Mats
    KTH, School of Engineering Sciences (SCI), Physics.
    Danielsson, Mats
    KTH, School of Engineering Sciences (SCI), Physics.
    Physical characterization of a scanning photon counting digital mammography system based on Si-strip detectors2007In: Medical physics (Lancaster), ISSN 0094-2405, Vol. 34, no 6, p. 1918-1925Article in journal (Refereed)
    Abstract [en]

    The physical performance of a scanning multislit full field digital mammography system was determined using basic image quality parameters. The system employs a direct detection detector comprised of linear silicon strip sensors in an edge-on geometry connected to photon counting electronics. The pixel size is 50 mu m and the field of view 24 x 26 cm(2). The performance was quantified using the presampled modulation transfer function, the normalized noise power spectrum and the detective quantum efficiency (DQE). Compared to conventional DQE methods, the scanning geometry with its intrinsic scatter rejection poses additional requirements on the measurement setup, which are investigated in this work. The DQE of the photon counting system was found to be independent of the dose level to the detector in the 7.6-206 mu Gy range. The peak DQE was 72% and 73% in the scan and slit direction, respectively, measured with a 28 kV W-0.5 mm Al anodefilter combination with an added 2 mm Al filtration.

  • 121161.
    Åslund, Magnus
    et al.
    KTH, School of Engineering Sciences (SCI), Physics.
    Cederström, Björn
    KTH, School of Engineering Sciences (SCI), Physics.
    Lundqvist, Mats
    KTH, School of Engineering Sciences (SCI), Physics.
    Danielsson, Mats
    KTH, School of Engineering Sciences (SCI), Physics, Medical Imaging.
    Scatter rejection in multislit digital mammography2006In: Medical physics (Lancaster), ISSN 0094-2405, Vol. 33, no 4, p. 933-940Article in journal (Refereed)
    Abstract [en]

    The scatter to primary ratio (SPR) was measured on a scanning multislit full-field digital mammography system for different thickness of breast equivalent material and different tube voltages. Scatter within the detector was measured separately and was found to be the major source of scatter in the assembly. Measured total SPRs below 6% are reported for breast range 3-7 cm. The performance of the multislit assembly is compared to other imaging geometries with different scatter rejection schemes by using the scatter detective quantum efficiency.

  • 121162.
    Åslund, Magnus
    et al.
    KTH, School of Engineering Sciences (SCI), Physics.
    Fredenberg, Erik
    KTH, School of Engineering Sciences (SCI), Physics.
    Cederström, Björn
    KTH, School of Engineering Sciences (SCI), Physics.
    Danielsson, Mats
    KTH, School of Engineering Sciences (SCI), Physics.
    Spectral shaping for photon counting digital mammography2007In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 580, no 2, p. 1046-1049Article in journal (Refereed)
    Abstract [en]

    The spectral shaping properties of conventional filters have been evaluated for a photon counting digital mammography system, and the result has been compared with the theoretical spectrum from a multi-prism X-ray lens (MPL). The absorption filters and the MPL were evaluated using a theoretical model of the system which has been verified experimentally. The spectral shaping performance is quantified with the spectral quantum efficiency (SQE), calculated as the polychromatic signal-difference-to-noise ratio (SDNR) squared over the optimal monochromatic SDNR squared at the same average glandular dose. The MPL increases the SQE by 25% compared to the investigated absorption filter when compared with a Tungsten anode. This translates into a potential dose reduction of 20% at maintained SDNR.

  • 121163. Åslund, Mattias
    et al.
    Malmström, Mikael
    Swerim AB.
    Comparison of single pass and multiple pass measurements for ultrasonic attenuation2017Conference paper (Refereed)
  • 121164.
    Åslund, Peter
    KTH, Superseded Departments, Fibre and Polymer Technology.
    Dynamic measurement of water-induced roughening in paper surfaces by a new optical method2004Licentiate thesis, comprehensive summary (Other scientific)
  • 121165.
    Åslund, Peter
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    On Suction Box Dewatering Mechanisms2008Doctoral thesis, comprehensive summary (Other scientific)
    Abstract [en]

    In previous studies on suction box dewatering, three mechanisms were identified that determine the dry content of a web, viz. web compression, displacement of water by air and rewetting. In the present work, the relative importance of the three mechanisms was investigated through direct measurement of the web deformation, the dry content changes during and after the suction pulse, the air flow through the fibre network and the saturation of the web after the suction pulse. Suction pressure, suction time and rewetting time were varied. The experiments were done with chemical and mechanical pulp webs of various grammages.

    It was found that a large web deformation took place during the suction pulse, particularly at its beginning. Compression dewatering was found to be the most dominant dewatering mechanism. Displacement dewatering started after most of the web compression had occurred. Its contribution to the increase in dry content was most pronounced for higher suction pressures, longer suction times and for chemical pulp webs.

    A surprisingly large expansion of the web was observed immediately after the suction pulse. This expansion was the effect of rewetting. This rewetting strongly reduced the dry content of the web if the web had not been immediately separated from the forming fabric at the end of the suction pulse. Under the conditions studied, the decrease in dry content amounted to the order of 3 to 6 %. Rewetting was smaller for longer suction times and higher suction pressures. A considerable air flow through the web occurred under these conditions. This air flow apparently moved water from the forming fabric into the suction box, thus making less water available for rewetting. Rewetting for mechanical pulp webs was more pronounced and took place faster than for chemical pulps.

    The use of a membrane on top of the web during suction box dewatering proved to be advantageous for reducing the air flow through the web. However, under the conditions investigated, the dry content could not be improved. Although the web compression was increased when using a membrane, especially at a higher suction pressure, rewetting after the suction pulse had an even larger negative impact on the dry content, which, as a result, was lower.

  • 121166.
    Åslund, Peter
    et al.
    STFI-Packforsk AB.
    Vomhoff, Hannes
    STFI-Packforsk AB.
    Dewatering mechanisms and their influence on suction box dewatering processes: A literature review2008In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 23, no 4, p. 389-397Article in journal (Refereed)
    Abstract [en]

    This review summarizes the present knowledge of suction box dewatering mechanisms. In addition, existing and novel suction box dewatering processes are described for applications in the pulp and paper industry.

    Three mechanisms that determine the dry content of the web after suction box dewatering are identified, viz. web compression, displacement of water by air, and rewetting. Earlier work focused mainly on the influence of web properties and process parameters for the achievable dry content. That work did not give any information concerning the relative importance of the three mechanisms. There was no measurement of web compression or water displacement. Furthermore, the occurrence of rewetting was neglected by many researchers. A deeper knowledge and, above all, direct measurements are required to better describe suction box dewatering.

    Some interesting modified suction box dewatering processes were presented in the literature, For example, the use of a membrane on top of the web during dewatering is believed to have the potential for an increase in dry content and energy savings. This increase in dry content is consequently believed to be a result of an increase in web compression.

  • 121167.
    Åslund, Peter
    et al.
    STFI-Packforsk AB.
    Vomhoff, Hannes
    STFI-Packforsk AB.
    Evaluation of membrane-assisted dewatering on a pilot paper machine2008In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 23, no 2, p. 152-155Article in journal (Refereed)
    Abstract [en]

    A membrane-assisted dewatering process was evaluated on a pilot paper machine. In this process, a membrane is located on top of the wet web when it passes over the suction box in the forming section. The intentions are twofold. Firstly, the dry content of the web should be increased by a more uniform compression, primarily in the thickness direction. Secondly, the airflow into the suction box should be reduced. The trials were performed using a specially designed membrane loop located at the end of the fourdrinier forming section of STFI-Packforsk's pilot paper machine EuroFEX. Two different membranes were tested. The use of a membrane resulted in a significant decrease in air consumption to achieve the same dry content of the web at the end of the wire section. To increase the dry content of the web, the structure of the membrane is important.

  • 121168.
    Åslund, Peter
    et al.
    STFI-Packforsk AB.
    Vomhoff, Hannes
    STFI-Packforsk AB.
    Method for studying the deformation of a fibre web during a suction pulse2008In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 23, no 4, p. 398-402Article in journal (Refereed)
    Abstract [en]

    A laboratory suction box was built to study the dynamic thickness deformation of a fibre web during a suction pulse. Both the pressure in the suction box and the duration of the suction pulse are adjustable in ranges of 0 to -40 kPa and 50 ms to 10 s, respectively During and after the suction pulse, the web thickness and the suction pressures can be measured. Furthermore, the air flow through the web can be calculated after the experiment.

    The first evaluation of the performance of the laboratory suction box shows that the web is considerably compressed, especially during the initial phase of the suction pulse. This indicates that web compression is an important dewatering mechanism. After the suction pulse, a rapid and significant web expansion was observed, implying that considerable rewetting probably occurs.

  • 121169.
    Åslund, Peter
    et al.
    STFI-Packforsk AB.
    Vomhoff, Hannes
    STFI-Packforsk AB.
    Web deformation during membrane-assisted dewatering2008In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 23, no 4, p. 415-419Article in journal (Refereed)
    Abstract [en]

    The potential of membrane-assisted dewatering was evaluated on a laboratory suction box. Different membranes, one impermeable and two permeable membranes were placed on top of the wet web, while a suction pulse was exerted underneath the web. The deformation of the wet web and the dry content of the web were determined approx. 30 seconds after the suction pulse. The results of these experiments were compared with results of those carried out without a membrane.

    A significantly higher web compression was observed at the end of the suction pulse when a membrane was used. The increased web compression that occurred when using a membrane corresponded to a dry content of 3 to 4%. The highest dry content values were obtained, however, when no membrane was applied. This contradiction was interpreted as a higher rewetting after the suction pulse when a membrane was used. Here, due to the reduced air flow through both the web and the forming fabric, it is likely that more water was available in the forming fabric for rewetting. Apparently, the air flow removed water from the forming fabric that otherwise would have been rewetted by the web.

  • 121170.
    Åslund, Peter
    et al.
    STFI-Packforsk AB.
    Vomhoff, Hannes
    STFI-Packforsk AB.
    Waljanson, Alexander
    STFI-Packforsk AB.
    External rewetting after suction box dewatering2008In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 23, no 4, p. 409-414Article in journal (Refereed)
    Abstract [en]

    A method has been developed to enable external rewetting to be measured during suction box dewatering. In a laboratory suction box, webs were instantaneously separated from the forming fabric at defined times, both during and after the suction pulse. External rewetting was measured for webs of mechanical (50, 100 g/m(2)) and chemical pulp (100, 200 g/m(2)). Suction pulses with a pressure drop of 10 and 40 kPa, and duration of 50 to 1000 ms were used. A considerable external rewetting was observed occurring primarily directly after the end of the suction pulse. Under the process conditions investigated, rewetting accounted for a dry content decrease of between 3 and 6%.

  • 121171.
    Åslund, Peter
    et al.
    STFI-Packforsk AB.
    Vomhoff, Hannes
    STFI-Packforsk AB.
    Waljanson, Alexander
    STFI-Packforsk AB.
    The deformation of chemical and mechanical pulp webs during suction box dewatering2008In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 23, no 4, p. 403-408Article in journal (Refereed)
    Abstract [en]

    The deformation of the paper web during and after a suction pulse on initially saturated fibre web made of chemical and mechanical pulp was investigated. A laboratory suction box was used, where the suction time and pressure drop could be varied and controlled. During the experiments, the web thickness, the air flow through the web and the suction pressure were recorded and after the experiments, the dry content of the web was determined.

    A large deformation was observed when the suction pulse was applied. After the suction pulse, a considerable expansion of the web took place, probably an effect of rewetting. The compression of the web appeared to be the most important dewatering mechanism increasing the dry content of the web. However, if the web is not separated from the forming fabric, rewetting after the suction pulse will greatly reduce the dry content.

  • 121172.
    Åslund, Rikard
    KTH, School of Computer Science and Communication (CSC).
    Network Communication for a MMORPG on Android.2011Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This report explore the possibilities of developing an Android version of the currently in development game Salem. The focus is on network communications, but due to the nature of the problem subjects like memory allocations and graphics are also touched upon. The results presented indicates that it is without a doubt possible to develop a game like Salem for the Android platform, but one need to consider the limitations and possibilities of the platform. The importance of maintaining a high transfer rate is stressed and the reader is presented with a protocol that helps in maintaining that.

    The report ends with concluding that the network communication on the Android mobile device can be viewed as both stable and unstable, and that one needs to acknowledge that cases with sudden increase in instability do occur and are necessary to handle appropriately.

  • 121173.
    Åsman, Christer
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.), Entrepreneurship and innovation.
    Wahldén, Henning
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.), Entrepreneurship and innovation.
    Leverantörer av utrustning och tjänster försmåskalig vattenkraft2013Independent thesis Basic level (university diploma), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    By request of the Swedish Hydropower Association a market survey of companies that operates

    in or in close cooperation with the small hydro power market was undertaken during the spring of

    2012. The association has noticed a surge in interest regarding small hydro power from both

    domestic and foreign entities and wants to proactively engage this interest.

    The main methods used to survey the market was to interview a handful of small hydropower

    plant owners and contact owners of hydropower plants and members of the Swedish Hydropower

    Association that had listed an e-mail address. The fundamental question is what companies the

    interviewees have come in contact with in regards to things related to the power plant. An early

    draft of the pre-defined criteria is used as support. Besides choosing the companies in regards to

    their responses to the interviews, some companies are also selected from appearing in the

    Swedish Hydropower Association members cadastral who are supporting members and

    companies that have published adverts during the last five years in the SERO-journal, a trade

    journal.

    The design of the survey sets the standard for how the companies are presented. The first part

    describes general information, if available. This is information such as company representative

    and a brief description of what the company does. The information following is what services and

    products the company offer in what categories. The categories has been determined by comparing

    how similar trade organizations have set up their categories, this combined with the results from

    interviews and surveys sets the structure for our categorization of activities.

  • 121174. Åstebro, Thomas
    et al.
    Braunerhjelm, Pontus
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.), Entrepreneurship and innovation. KTH, School of Industrial Engineering and Management (ITM), Centres, Centre of Excellence for Science and Innovation Studies, CESIS.
    Broström, Anders
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.), Entrepreneurship and innovation. KTH, School of Industrial Engineering and Management (ITM), Centres, Centre of Excellence for Science and Innovation Studies, CESIS.
    Does academic entrepreneurship pay?2013In: Industrial and Corporate Change, ISSN 0960-6491, E-ISSN 1464-3650, Vol. 22, no 1, p. 281-311Article in journal (Refereed)
    Abstract [en]

    We investigate the private returns for academics that start new businesses. Total earnings for the universe of 478 individuals working at Swedish universities who quit to become full-time entrepreneurs between 1999 and 2008 are compiled. To the best of our knowledge, this is the first analysis of entrepreneurial returns to include capital gains. Entrepreneurship for academics appears a gradual process and episodic. Earnings are similar before and after becoming an entrepreneur, and dividends and capital gains are inconsequential. But the income risk is more than three times higher in entrepreneurship.

  • 121175.
    Åstedt, Björn
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Structural Design and Bridges.
    Analys av system bestående av skivor, kopplade skivor och ramar med språngvisa styvhetsförändringar i höga byggnader2004Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 121176.
    Åstrand, Erik
    et al.
    Volvo Construction Equipment AB.
    Stenberg, Thomas
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Jonsson, Bertil
    Volvo Construction Equipment AB.
    Barsoum, Zuheir
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Welding procedures for fatigue life improvement of the weld toe2016In: Welding in the World, ISSN 0043-2288, E-ISSN 1878-6669, Vol. 60, no 3, p. 573-580Article in journal (Refereed)
    Abstract [en]

    This paper presents the results of an experimental study of gas metal arc welded, GMAW, cruciform joints made of common construction steel S355. The hypothesis is that smooth undercuts in as welded conditions can give enhanced fatigue properties similarly as post treated welds. Undercuts are generally seen as a defect or imperfection. Welders try to avoid these and repair them when they occur, which result in increased production lead time. Post weld improvement methods i.e. grinding or high-frequency-impact treatment (HFMI) as fatigue-enhancing post-treatment methods enforce amongst other effects a certain smooth undercut-shaped groove in the treated weld toe region. The obtained shallower weld toe transition reduces the geometrical notch effect and increases fatigue strength. This paper presents a study whereas welded specimens with a weld toe geometry similar to what is obtained by weld toe grinding or HFMI-treatment, has been produced, fatigue tested and analyzed. The improvement of the fatigue strength is comparable to post-weld treated specimens. It has proven to be an efficient way to achieve high-quality welds without introducing any additional operations in production, thus enabling weight reduction using cost-effective methods.

  • 121177.
    Åstrand, Maria
    KTH, School of Industrial Engineering and Management (ITM), Industrial Ecology.
    Studier av metoder som kan reducera utsläpp av vattenburet fosfor från Korsnäsverken2006Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This Master’s thesis has been written in cooperation with the paper mill Korsnäsverken,owned by Korsnäs AB, which is located in Gävle, Sweden. The aim of the project: On the basis of earlier received knowledge, from the currents in the external wastewatertreatment system at Korsnäsverken, propose suitable ways of reducing the emissions ofdissolved phosphorus to the recipient.

    Since emissions of the growth-regulating nutrient phosphorus from Korsnäsverken may cause eutrophication, in their recipient the Baltic Sea, the regional environmental court has decided that the paper mill must reduce their phosphorous emissions by half.

    The experiments performed during this thesis were focused on chemical reduction. The other reducing methods described have been examined by literature studies. The water dissolved phosphorous has, in an earlier Master’s thesis, been located to certain currents in the external wastewater treatment system of Korsnäsverken and was further examined in the experimentsof this thesis. The used water in the experiments was taken from the bleach pond (AVB) andthe end sedimentation pond (Sed.zon).

    The results, from chemical reducing experiments in Sed.zon, showed that Korsnäsverkencould probably meet the condition set by the regional environmental court and reduce the emissions of phosphorus with 50 %. (Red bars in figure 1.) It furthermore showed that chemical reduction with polymer alone in Sed.zon could probably also reduce phosphorus by50 %. In AVB the result of chemical reduction was positive, but not as efficient as that of Sed.zon.

  • 121178.
    Åstrand, Max
    KTH, School of Electrical Engineering and Computer Science (EECS), Automatic Control.
    Short-term Underground Mine Scheduling: Constraint Programming in an Industrial Application2018Licentiate thesis, monograph (Other academic)
    Abstract [en]

    The operational performance of an underground mine depends critically on how the production is scheduled. Increasingly advanced methods are used to create optimized long-term plans, and simultaneously the actual excavation is getting more and more automated. Therefore, the mapping of long-term goals into tasks by manual short-term scheduling is becoming a limiting segment in the optimization chain. In this thesis we study automating the short-term mine scheduling process, and thus contribute to an important missing piece in the pursuit of autonomous mining.

    First, we clarify the fleet scheduling problem and the surrounding context. Based on this knowledge, we propose a flow shop that models the mine scheduling problem. A flow shop is a general abstract process formulation that captures the key properties of a scheduling problem without going into specific details. We argue that several popular mining methods can be modeled as a rich variant of a k-stage hybrid flow shop, where the flow shop includes a mix of interruptible and uninterruptible tasks, after-lags, machine unavailabilities, and sharing of machines between stages.

    Then, we propose a Constraint Programming approach to schedule the underground production fleet. We formalize the problem and present a model that can be used to solve it. The model is implemented and evaluated on instances representative of medium-sized underground mines.

    After that, we introduce travel times of the mobile machines to the scheduling problem. This acknowledges that underground road networks can span several hundreds of kilometers. With this addition, the initially proposed Constraint Programming model struggles with scaling to larger instances. Therefore, we introduce a second model. The second model does not solve the interruptible scheduling problem directly; instead, it solves a related uninterruptible problem and transforms the solution back to the original time domain. This model is significantly faster, and can solve instances representative of large-sized mines even when including travel times.

    Lastly, we focus on finding high-quality schedules by introducing Large Neighborhood Search. To do this, we present a domain-specific neighborhood definition based on relaxing variables corresponding to certain work areas. Variants of this neighborhood are evaluated in Large Neighborhood Search and compared to using only restarts. All methods and models in this thesis are evaluated on instances generated from an operational underground mine.

     

     

  • 121179.
    Åstrand, Max
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Automatic Control. ABB Corp Res, Control Optimizat & Analyt, Automat Solut, Vasteras, Sweden.
    Johansson, Mikael
    KTH, School of Electrical Engineering and Computer Science (EECS), Automatic Control.
    Greberg, J.
    Lulea Univ Technol, Dept Civil Environm & Nat Resources Engn, Div Min & Geotech Engn, Lulea, Sweden..
    Underground mine scheduling modelled as a flow shop: a review of relevant work and future challenges2018In: The Southern African Journal of Mining and Metallurgy, ISSN 2225-6253, E-ISSN 1543-9518, Vol. 118, no 12, p. 1265-1276Article, review/survey (Refereed)
    Abstract [en]

    Advanced planning and automation are increasingly important in modern mines. Sophisticated methods for long-term mine planning are often used, and the advent of autonomous machines makes the actual operation more predictable. However, the interface between these two timescales, i.e. the scheduling of the mobile production fleet, often limits the ability to operate mines at maximum profitability. We show how scheduling the production fleet in an underground mine can be modelled as a flow shop. A flow shop is a general abstract process formulation that captures the key properties of a scheduling problem without going into specific details. Thus, the flow shop enables mine scheduling to reap the benefits of scheduling research from other industries. We review recent results from the mining community and the flow shop community, and introduce scheduling methods used in these two fields. This work aims at providing value to researchers from the mining community who want to leverage their skill set, as well as to theoretical researchers by presenting the mining process as a potential application area. Lastly, we discuss the results, and outline some future challenges and opportunities facing the industry.

  • 121180.
    Åstrand, Max
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Automatic Control. ABB Corp Res, Control Optimizat & Analyt, Automat Solut, Vasteras, Sweden.;KTH Royal Inst Technol, Dept Automat Control, Sch Elect Engn, Stockholm, Sweden..
    Johansson, Mikael
    KTH, School of Electrical Engineering and Computer Science (EECS), Automatic Control. KTH Royal Inst Technol, Dept Automat Control, Sch Elect Engn, Stockholm, Sweden..
    Greberg, J.
    Lulea Univ Technol, Dept Civil Environm & Nat Resources Engn, Div Min & Geotech Engn, Lulea, Sweden..
    Underground mine scheduling modelled as a flow shop: a review of relevant work and future challenges2018In: The Southern African Journal of Mining and Metallurgy, ISSN 2225-6253, E-ISSN 1543-9518, Vol. 118, no 12, p. 1265-1276Article, review/survey (Refereed)
    Abstract [en]

    Advanced planning and automation are increasingly important in modern mines. Sophisticated methods for long-term mine planning are often used, and the advent of autonomous machines makes the actual operation more predictable. However, the interface between these two timescales, i.e. the scheduling of the mobile production fleet, often limits the ability to operate mines at maximum profitability. We show how scheduling the production fleet in an underground mine can be modelled as a flow shop. A flow shop is a general abstract process formulation that captures the key properties of a scheduling problem without going into specific details. Thus, the flow shop enables mine scheduling to reap the benefits of scheduling research from other industries. We review recent results from the mining community and the flow shop community, and introduce scheduling methods used in these two fields. This work aims at providing value to researchers from the mining community who want to leverage their skill set, as well as to theoretical researchers by presenting the mining process as a potential application area. Lastly, we discuss the results, and outline some future challenges and opportunities facing the industry.

  • 121181.
    Åstrand, Max
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Automatic Control. ABB Corporate Research Center, Västerås, Sweden.
    Johansson, Mikael
    KTH, School of Electrical Engineering and Computer Science (EECS), Automatic Control.
    Zanarini, A.
    Fleet scheduling in underground mines using constraint programming2018In: 15th International Conference on Integration of Constraint Programming, Artificial Intelligence, and Operations Research, CPAIOR 2018, Springer, 2018, Vol. 10848, p. 605-613Conference paper (Refereed)
    Abstract [en]

    The profitability of an underground mine is greatly affected by the scheduling of the mobile production fleet. Today, most mine operations are scheduled manually, which is a tedious and error-prone activity. In this contribution, we present and formalize the underground mine scheduling problem, and propose a CP-based model for solving it. The model is evaluated on instances generated from real data. The results are promising and show a potential for further extensions.

  • 121182.
    Åstrand, Max
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Automatic Control. ABB Corporate Research, Sweden.
    Saarinen, K.
    Sander-Tavallaey, S.
    Surrogate models for design and study of underground mine ventilation2018In: 22nd IEEE International Conference on Emerging Technologies and Factory Automation, ETFA 2017, Institute of Electrical and Electronics Engineers (IEEE), 2018, p. 1-8Conference paper (Refereed)
    Abstract [en]

    Ventilation is vital for the production in an underground mine. Therefore, it is important to have efficient and accurate design tools in order to ensure and optimize the airflows in the mine. There are several commercial software for airflow simulation based on first principles. However, the computational cost of simulation together with integrational obstacles when connecting simulation to control strategies limits the benefit of these tools. In this paper an approach utilizing surrogate models as a complementary design tool is presented. It is shown that using surrogate models one can with rather low computational expense evaluate and benchmark different control strategies. It is also shown that the models can be used for identifying possible bottlenecks in the system in advance. Moreover, the use of surrogate models transfer the simulation into a development-friendly environment (such as Matlab). A test case is used based on a real underground mine ventilation design. Two types of surrogate models are fitted to process data; multiple least squares regression and a Gaussian process model. Sensitivity analysis on the surrogate shows the potential of using surrogate models for identifying bottlenecks. Furthermore, the surrogate is used to benchmark two different control strategies for mine ventilation.

  • 121183.
    Åstrand, Mie
    KTH, School of Industrial Engineering and Management (ITM), Applied Mechanical Engineering (KTH Södertälje).
    Absorbera färdiglager i utleveransprocessen -En fallstudie2014Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
  • 121184.
    Åstrand, Mikael
    KTH, School of Biotechnology (BIO).
    Affinity ligand selection using the ABD scaffold for targeting tumor biomarkers Her2 and Her32011Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
  • 121185.
    Åstrand, Mikael
    KTH, School of Biotechnology (BIO), Protein Technology.
    Engineering strategies for ABD-derived affinity proteins for therapeutic and diagnostic applications2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Small stable protein domains are attractive scaffolds for engineering affinity proteins due to their high tolerance to mutagenesis without loosing structural integrity. The albuminbinding domain is a 5 kDa three-helix bundle derived from the bacterial receptor Protein G with low-nanomolar affinity to albumin. In this thesis, the albumin-binding domain is explored as a scaffold for engineering novel affinity proteins with the possible benefit of combining a prolonged serum half-life with specific targeting in a single small scaffold protein. Previously, a library was created by randomizing surface-exposed residues in order to engineer affinity to a new target antigen in addition to the inherent albumin affinity. Here, phage display selections were separately performed against the tumor antigens ERBB2 and ERBB3. The ERBB3 selection resulted in a panel of candidates that were found to have varying affinities to ERBB3 in the nanomolar range, while still retaining a high affinity to albumin. Further characterization concluded that the clones also competed for binding to ERBB3 with the natural activating ligand Heregulin. The selections against ERBB2 resulted in sub-nanomolar affinities to ERBB2 where the binding site was found to overlap with the antibody Trastuzumab. The binding sites on ABD to albumin and either target were found in both selections to be mutually exclusive, as increased concentrations of albumin reduced the level of binding to ERBB2 or ERBB3. An affinity-matured ERBB2 binder, denoted ADAPT6, which lacked affinity to albumin was evaluated as a radionuclide-labeled imaging tracer for diagnosing ERBB2-positive tumors. Biodistribution studies in mice showed a high renal uptake consistent with affinity proteins in the same size range and the injected ADAPT quickly localized to the implanted tumor. High contrast images could be generated and ERBB2-expressing tissue could be distinguished from normal tissue with high contrast, demonstrating the feasibility of the scaffold for use as diagnostic tool. In a fourth study, affinity maturation strategies using staphylococcal cell-surface display were evaluated by comparing two replicate selections and varying the stringency. A sub-nanomolar target concentration was concluded to be inappropriate for equilibrium selection as the resulting output was highly variable between replicates. In contrast, equilibrium sorting at higher concentrations followed by kinetic-focused off-rate selection resulted in high output overlap between attempts and a clear correlation between affinity and enrichment.

  • 121186.
    Åstrand, Mikael
    et al.
    KTH, School of Biotechnology (BIO), Protein Technology.
    Nilvebrant, Johan
    KTH, School of Biotechnology (BIO), Protein Technology. Centre for Cellular and Biomolecular Research, Donnelly Centre, University of Toronto, Toronto, ON, Canada.
    Björnmalm, Mattias
    KTH, School of Biotechnology (BIO), Protein Technology. Department of Chemical and Biomolecular Engineering, University of Melbourne, Parkville, VIC, Australia.
    Lindbo, Sarah
    KTH, School of Biotechnology (BIO), Protein Technology.
    Hober, Sophia
    KTH, School of Biotechnology (BIO), Protein Technology.
    Löfblom, John
    KTH, School of Biotechnology (BIO), Protein Technology.
    Investigating affinity-maturation strategies and reproducibility of fluorescence-activated cell sorting using a recombinant ADAPT library displayed on staphylococci2016In: Protein Engineering Design & Selection, ISSN 1741-0126, E-ISSN 1741-0134, Vol. 29, no 5, p. 187-195Article in journal (Refereed)
    Abstract [en]

    During the past decades, advances in protein engineering have resulted in the development of various in vitro selection techniques (e.g. phage display) to facilitate discovery of new and improved proteins. The methods are based on linkage between genotype and phenotype and are often performed in successive rounds of selection. Since the resulting output depends on the selection pressures used and the applied strategy, parameters in each round must be carefully considered. In addition, studies have reported biases that can cause enrichment of unwanted clones and/or low correlation between abundance in output and affinity. We have recently developed a selection method based on display of protein libraries on Staphylococcus carnosus and isolation of affinity proteins by fluorescence-activated cell sorting. Here, we compared duplicate selections for affinity maturation using equilibrium binding at different target concentrations and kinetic off-rate selection. The results showed that kinetic selection is efficient for isolation of high-affinity binders and that equilibrium selection at subnanomolar concentrations should be avoided. Furthermore, the reproducibility of the selection was high and a clear correlation was observed between enrichment and affinity. This work reports on the reproducibility of bacterial display in combination with FACS and provides insights into selection design to help guide the development of new affinity proteins.

  • 121187. Åström, Alexander
    et al.
    Izosimov, Viacheslav
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Mechatronics.
    Örsmark, Ola
    Efficient Software Tool Qualification for Automotive Safety-Critical Systems2011Conference paper (Other academic)
  • 121188.
    Åström, Axel
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Building Technology.
    Täta tak: en guide till skadefria takpannetak2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    I undersökningar av byggnadsskador visar sig takskador vara ett av de vanligaste förekommande problemen. Taktäckning med takpannor är det vanligaste i det Svenska  byggbeståndet. Arbetet är utfört med en litteraturstudie, fallstudie av nio skaderapporter ifrån Anticimex samt sju dokumenterade rivningar av tak i mälardalen. Både i litteraturstudien och fallstudierna pekar på att genomföringarna och anslutningarna på takpannetaken är de mest skadedrabbade områdena. Brister i uppdrag av underlagspapp är i fallstudierna vanligt förekommande, och har i flera fall lett till byggnadsskador. Vid omläggning av tak sparas ofta gamla plåtdetaljer vilket är en trolig förklaringen till att uppdrag av underbeslag och papp blir bristfällig. Genomföringsmanschetter och andra prefabricerade lösningar för tätning av stosar rekommenderas. Läktskiktet skall hållas fritt från skräp för att motverka röta av läkten, frostskador av takpannor och att minska vindlasten av takpannorna.  För att ge tillräcklig ventilation av takpannorna bör ströläkten vara minst 25mm i höjd, anpassning till större läkt kan ske vid flackare taklutningar. Skräp och yrsnö motverkas vid användning av nockband och fågellist i takfoten. 

  • 121189. Åström Borinder, Carin
    et al.
    Aune, Ragnhild E.
    KTH, School of Industrial Engineering and Management (ITM).
    Seetharaman, Seshadri
    KTH, School of Industrial Engineering and Management (ITM).
    Thermodynamic Assessment of Rare Earths. I: Review of Thermodynamic Properties of Rare Earth Oxide Systems1991Report (Refereed)
  • 121190.
    Åström, Emil
    KTH, School of Information and Communication Technology (ICT).
    Task Scheduling in Distributed Systems: Model and prototype2016Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Distributed systems is a collection of entities that cooperate to solve a problem that otherwise a single entity would not be able to solve. The use of heavy algorithms has been growing and therefore have distributed computation systems arisen. To make the best use of a distributed computation system task allocation and task scheduling algorithms has been developed. Task allocation is the process of allocating tasks to the best suitable processors of the system while task scheduling is used to determine the execution order of tasks. In some cases task scheduling also incorporate allocation process. A task is the smallest entity that can be scheduled and can be a process or a thread. Tasks are often bunched together as jobs which can include an arbitrary number of tasks. In this thesis has a general model and prototype been created which can be used in a variety of distributed systems and handle a wide range of tasks which includes tasks with execution order and deadlines. The model has been created using the best methods examined during a literature study which include the use of batch sampling, late binding and fair scheduling. A bare bone prototype has been created from the model which includes some core functionality and has been tested in regards to throughput and how balanced load it is. The throughput tests showed that the model does not lose throughput when tasks with execution order is scheduled and the load test showed that the system is fairly balanced. An evaluation of the model has been performed which shows that it works well in distributed systems and can handle a variety of tasks. The prototype has been has been tested in a small test environment which shows that it works well in smaller environments with similar requirements.

  • 121191.
    Åström Fransson, Donny
    KTH, School of Information and Communication Technology (ICT), Electronic, Computer and Software Systems, ECS.
    Utilizing Multicore Processors with Streamed Data Parallel Applications for Mobile Platforms2012Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Performance has always been a major concern among computers and microprocessors. So have the qualities of the applications that are executed by these processors. When the multicore evolution began, programmers faced a shift in programming paradigms required to utilize the full potential of these processors. Now that the same evolution has reached the market of mobile devices, the developers focusing on mobile platforms are facing the same challenge.

    This thesis focuses on assessing some of the possible application quality gains that can be achieved by adopting parallel programming techniques for mobile platforms. In particular, throughput performance, low-latency performance and power consumption.

    A Proof of Concept application was developed to measure these specific qualities using a streamed data parallel approach. By adopting proper parallel programming techniques to utilize the multicore processor architecture, it was possible to achieve 90% better throughput performance or the same latency quality with 60% lower CPU frequency. Unfortunately, the power consumption could not be accurately measured using the available hardware.

  • 121192.
    Åström, Frida
    KTH, School of Industrial Engineering and Management (ITM), Industrial Economics and Management (Dept.).
    How dose Human resource management contribute to the business performance: - A case study2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 121193.
    Åström, Hannes
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Förbättring av arbetsförhållande i skördare2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    AbstractThe working conditions in the harvester are not very good. The shifts are often long and possibility to change working posture is poor and the operator remains seated all the timed during the process of cutting the trees and driving the machine. The human body is made to be in movement, not still. Sedentary itself is bad on health and may in worse cases lead to a premature death. Seated posture has several negative impacts on the human body.Work intensity in the harvester is high and the cycles are short and repetitive. The same muscle fibers are therefore continuously strained and tend to be exhausted. The operator is under a lot of stress. Stress in combination with muscular load will make it more harmful.The cost for the operators work related disorders manifests itself in reduced production, not used machines as a result from sick leave and in cases with long-term sickness, recruitment and training costs. By improving the working conditions it’s possible to reduce these costs and at best eliminated them. It leads probably also to a higher productivity in healthy drivers.To improve the working conditions for the operator of the harvester a concept for the seat, armrest and steering controls have been developed. The concept offers more variation in work pattern and more working postures. The steering controls have new shapes and offer two different ways of steering the crane that activates different muscles. The seat could be raised so that the work could be done from a standing position. Standing gets the spine in its neutral curvature with low pressure on the intervertebral discs, it enables a deeper breathing and an improved bowel movement. Being able to switch between seated and standing position leads to a varied load on the body and it also increases the blood circulation which helps recovery. The seat could be turn into a divided saddle seat. Saddle seats offer a position that could be seen as a mix between standing and seated position. Then spine gets in its natural position as it does while standing. At the same time the legs could be relaxed and the bodyweight rests upon the seat bones. The difference between a divided saddle seat and an ordinary is that the pressures on the genitals are much lower with the divided. Also the genitals temperature gets lower.The developed concept has been modeled in CAD. A physical prototype of the steering controls have been made that could be connected to a simulator for evaluation.

  • 121194. Åström, J.A.
    et al.
    Carter, A.
    Hetherington, J.
    Ioakimidis, K.
    Lindahl, Erik
    KTH, School of Engineering Sciences (SCI), Theoretical Physics, Theoretical & Computational Biophysics. KTH, Centres, Science for Life Laboratory, SciLifeLab.
    Mozdzynski, G.
    Nash, R. W.
    Schlatter, Philipp
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Signell, A.
    Westerholm, J.
    Preparing scientific application software for exascale computing2013In: Applied Parallel and Scientific Computing: 11th International Conference, PARA 2012, Helsinki, Finland, June 10-13, 2012, Revised Selected Papers / [ed] Pekka Manninen, Per Öster, Springer, 2013, p. 27-42Conference paper (Refereed)
    Abstract [en]

    Many of the most widely used scientifc application software of today were developed largely during a time when the typical amount of compute cores was calculated in tens or hundreds. Within a not too distant future the number of cores will be calculated in at least hundreds of thousands or even millions. A European collaboration group CRESTA has recently been working on a set of renowned scientific software to investigate and develop these codes towards the realm of exascale computing. The codes are ELMFIRE, GROMACS, IFS, HemeLB, NEK5000, and OpenFOAM. This paper contains a summary of the strategies for their development towards exascale and results achieved during the first year of the collaboration project.

  • 121195.
    Åström, Joachim
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment.
    Granberg, Mikael
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment.
    Khakee, Abdul
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment.
    Apple Pie-Spinach Metaphor: Shall e-Democracy make Participatory Planning More Wholesome?2011In: Planning Practice & Research, ISSN 0269-7459, Vol. 26, no 5, p. 571-586Article in journal (Refereed)
    Abstract [en]

    Despite claims that planners' attitude towards public participation has not always been enthusiastic, there have been genuine attempts to devolve powers through participation-although seldom with success. In this paper we discuss several major attempts to improve participation in Sweden including case studies of e-participation. Despite great expectations on information and communication technologies, Swedish experience indicates that the status quo between planners and people remains.

  • 121196.
    Åström, K.
    KTH, Superseded Departments.
    On relativistic dust grains and extensive air showers1977Report (Other academic)
  • 121197. Åström, K. J.
    et al.
    Johansson, Karl H.
    KTH, Superseded Departments, Signals, Sensors and Systems.
    Wang, Qing-Guo
    Design of decoupled PID controllers for MIMO systems2001In: Proceedings of the 2001 American Control Conference, IEEE , 2001, p. 2015-2020Conference paper (Refereed)
    Abstract [en]

    The design of PID controllers for systems with interacting loops is discussed. It is important to deal with the interaction at the lower-level loops, since supervisory control based on for instance MPC seldom has sufficient bandwidth. A new scheme based on modified scalar PID design and static decoupling is developed, where the frequency characteristics of the coupling between the lower-level loops is taken into account. This leads to a design method emphasizing the trade-off between the individual loop performances and the so called interaction indices. The controller is easily implemented, due to its simple configuration based on standard components. The method is applied to a couple of examples.

  • 121198.
    Åström, Katja
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Utveckling av en induktionsladdare för bärbara datorer2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This report was written in conjunction with a bachelor’s work within Engineering Design, during spring 2014, at the Royal Institute of Technology in Stockholm. The aim was to develop a product focusing on both technical and design aspects while at the same time deepening previously acquired knowledge in product development, mechanical engineering, electrical engineering and mathematics.The product that was developed was an inductive charger for laptops, which has not existed on the market before. The aim was to develop a wireless charger as a complement to existing chargers, for times when it is impractical to look for charging jacks and fiddle about with wires. The focus was on applying available technology within a new area rather than developing the technology itself.The result was a portable inductive charger that charges the computer when plugged-in and placed on a table with a built-in charging station. The inductive effect is enhanced by a magnetic ferrite core. Besides, the product is compatible with different types of computers thanks to its adjustable voltage level and universal socket.The groundwork began with an extensive information search about induction and different usage areas. The inductive charging method varies depending on the usage area and by mapping these areas, methods applicable to the project were found. This was followed by a market research and costumer research, followed by a concept development process where pros and cons of different concepts were weighed against each other. During the development of the product, economic, social, environmental and operational aspects were considered. At the end of the report an analysis of the project is presented.

  • 121199.
    Åström, Kjell
    KTH, Superseded Departments.
    Beräkning av my-mesonernas energispektrum vid jordytan i zenitriktningen1981Report (Other academic)
  • 121200. Åström, Mats E.
    et al.
    Nystrand, Miriam
    Gustafsson, Jon Petter
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Österholm, Peter
    Nordmyr, Linda
    Reynolds, Jason K.
    Peltola, Pasi
    Lanthanoid behaviour in an acidic landscape2010In: Geochimica et Cosmochimica Acta, ISSN 0016-7037, E-ISSN 1872-9533, Vol. 74, no 3, p. 829-845Article in journal (Refereed)
    Abstract [en]

    Lanthanoids were studied in a boreal landscape where an abundance of acid sulfate soils and Histosols provide a unique opportunity to increase the understanding of flow these metals behave in acidic soils and waters and interact with soil and aqueous organic matter. In the acid sulfate soils lanthanoids are mobile as reflected in high to very high concentrations in soil water and runoff (typically a few mg 1(-1) but Lip to 12 mg 1(-1)) and abundant release by several relatively weak extractants (ammonium acetate EDTA, sodium pyrophosphate, hydroxylamine hydrochloride) applied on bulk soil. Normalisation with the lanthanoid pool in the underlying parent materials (sulphide-bearing sediments deposited in brackish-water) and soil water showed that the extensive release/retention in the acidic soil was accompanied by large, and variable, fractionation trends across the lanthanoid series. In low-order streams draining these soils, the lanthanoid concentrations were high and, as indicated by frontal ultrafiltration and geochemical modelling, largely dissolved (<1 kDa) in the form of the species LnSO(4)(+) and Ln(3+). In other moderately acidic stream waters (pH 4.3-4.6), organic complexation was predicted to be important in the <1 kDa fraction (especially for the heavy lanthanoids) and strongly dominating in the colloidal phase (1 kDa-0.45 mu m). Along the main stem of a stream in focus (catchment area of 223 km(2)), lanthanoid concentrations increased downstream, in particular during high flows, caused by a downstream increase in the proportion of acid sulfate soils which are extensively flushed during wet periods. The geochemical models applied to the colloidal Ln-organic phase were not successful in predicting the measured fractionation patterns.

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