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  • 1. A, Ahmad
    et al.
    G, Bianchi
    L, Bernstein
    G, Fodor
    G, Pujolle
    LB, Sung
    YD, Yao
    QoS support and service differentiation in wireless networks2004Ingår i: International Journal of Communication Systems, ISSN 1074-5351, E-ISSN 1099-1131, Vol. 17, nr 6, 507-512 s.Artikel i tidskrift (Refereegranskat)
  • 2.
    A Asif, Farazee M
    KTH, Skolan för industriell teknik och management (ITM), Industriell produktion, Maskin- och processteknologi.
    Circular Manufacturing Systems: A development framework with analysis methods and tools for implementation2017Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The society today lives on the philosophy of ‘take-make-use-dispose.’ In the long run, this is not sustainable as the natural resources and the waste carrying capacity of the earth are limited. Therefore, it is essential to reduce dependency on the natural resources by decoupling the growth from the consumption. In this venture, both the society and the manufacturing industry have a vital role to play. The society needs to shift towards Circular Economy that rests upon the philosophy of ‘take-make-use-reuse’ and the manufacturing industry has to be a major stakeholder in this shift. Despite being proven to be both economically and environmentally beneficial, successful examples of circular systems are few today. This is primarily due to two reasons; firstly, there is a lack of systemic and systematic approach to guide industries and secondly, there is a lack of analysis methods and tools that are capable of assessing different aspects of circular manufacturing systems. Taking on to these challenges, the objective of this research is to bring forward a framework with methods and decision support tools that are essential to implement circular manufacturing systems. The initial conceptual framework with the systemic approach is developed based on extensive review and analysis of research, which is further adapted for industrial implementation. Systematic analysis methods, decision support and implementation tools are developed to facilitate this adaptation. This development has been supported by four cases from diverse manufacturing sectors. Behind each decision support tool, there are analysis methods built upon mainly system dynamics principles. These tools are based on simulation platforms called Stella and Anylogic. Among other things, these tools are capable of assessing the performance of closed-loop supply chains, consequences of resource scarcity, potential gains from resource conservation and overall economic and environmental performance of circular manufacturing systems.

  • 3.
    A Asif, Farazee M
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Industriell produktion, Maskin- och processteknologi.
    Rashid, Amir
    KTH, Skolan för industriell teknik och management (ITM), Industriell produktion, Maskin- och processteknologi.
    Bianchi, Carmine
    University of Palermo (ITALY) Faculty of Political Sciences - Department of International Studies .
    Nicolescu, Mihai
    KTH, Skolan för industriell teknik och management (ITM), Industriell produktion, Maskin- och processteknologi.
    Performance analysis of the closed loop supply chain2012Ingår i: Journal of Remanufacturing, ISSN 2210-4690, Vol. 2, nr 4Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Purpose

    The question of resource scarcity and emerging pressure of environmental legislations has brought a new challenge for the manufacturing industry. On the one hand, there is a huge population that demands a large quantity of commodities; on the other hand, these demands have to be met by minimum resources and pollution. Resource conservative manufacturing (ResCoM) is a proposed holistic concept to manage these challenges. The successful implementation of this concept requires cross functional collaboration among relevant fields, and among them, closed loop supply chain is an essential domain. The paper aims to highlight some misconceptions concerning the closed loop supply chain, to discuss different challenges, and in addition, to show how the proposed concept deals with those challenges through analysis of key performance indicators (KPI).

    Methods

    The work presented in this paper is mainly based on the literature review. The analysis of performance of the closed loop supply chain is done using system dynamics, and the Stella software has been used to do the simulation. Findings The results of the simulation depict that in ResCoM; the performance of the closed loop supply chain is much enhanced in terms of supply, demand, and other uncertainties involved. The results may particularly be interesting for industries involved in remanufacturing, researchers in the field of closed loop supply chain, and other relevant areas. Originality The paper presented a novel research concept called ResCoM which is supported by system dynamics models of the closed loop supply chain to demonstrate the behavior of KPI in the closed loop supply chain.

  • 4.
    A Elhassan, Amro
    KTH, Skolan för elektro- och systemteknik (EES).
    Building automation and control2012Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
  • 5. A, Eriksson
    et al.
    G, Fodor
    A middlebox control plane framework for wireless and mobile IP networks2004Ingår i: 2004 International Conference on Parallel Processing Workshops, 2004 (ICPP 2004 Workshops) / [ed] IEEE, New York: IEEE conference proceedings, 2004, 322-329 s.Kapitel i bok, del av antologi (Övrigt vetenskapligt)
    Abstract [en]

    In wireless and mobile IP networks there is a need to support a set of functions that are related to wireless QoS provisioning, resource optimizations, mobility and security management and operator policy enforcement. These requirements have lead to the frequent usage of so called middleboxes including header/payload compressors, performance enhancement proxies, tunnel endpoints, packet filters and redirectors, QoS schedulers and others. Unfortunately, the increasing usage of these types of devices often leads to undesirable artifacts called feature interactions. In this paper we propose a framework that aims to coordinate the operation of middleboxes such that feature interactions are avoided. The three main ideas are (1) the separation of the control plane from the distributed network nodes, (2) the usage of a middlebox function independent horizontal protocol that allows mobile hosts to communicate their desired service requests to the network and (3) the usage of a vertical protocol between the network control and user planes. We present two examples in which this framework helps eliminate the risk for feature interactions. We comment on the relationship between the end-to-end principle and this framework. Finally, we discuss how future middleboxes can fit into this framework.

  • 6.
    A, Fredrik
    et al.
    KTH, Skolan för elektro- och systemteknik (EES).
    Forsberg, A
    KTH, Skolan för elektro- och systemteknik (EES).
    Forsén, Tobias
    KTH, Skolan för elektro- och systemteknik (EES).
    Tracking Using Wireless Camera Networks2015Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
  • 7.
    A. M. Naiini, Maziar
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Horizontal Slot Waveguides for Silicon Photonics Back-End Integration2014Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    This thesis presents the development of integrated silicon photonic devices. These devices are compatible with the present and near future CMOS technology. High-khorizontal grating couplers and waveguides are proposed. This work consists of simulations and device design, as well as the layout for the fabrication process, device fabrication, process development, characterization instrument development and electro-optical characterizations.

    The work demonstrates an alternative solution to costly silicon-on-insulator photonics. The proposed solution uses bulk silicon wafers and thin film deposited waveguides. Back-end deposited horizontal slot grating couplers and waveguides are realized by multi-layers of amorphous silicon and high-k materials.

    The achievements of this work include: A theoretical study of fully etched slot grating couplers with Al2O3, HfO2 and AIN, an optical study of the high-k films with spectroscopic ellipsometry, an experimental demonstration of fully etched SiO2 single slot grating couplers and double slot Al2O3 grating couplers, a practical demonstration of horizontal double slot high-k waveguides, partially etched Al2O3 single slot grating couplers, a study of a scheme for integration of the double slot Al2O3  waveguides with selectively grown germanium PIN photodetectors, realization of test chips for the integrated germanium photodetectors, and study of integration with graphene photodetectors through embedding the graphene into a high-k slot layer.

    From an application point of view, these high-k slot waveguides add more functionality to the current silicon photonics. The presented devices can be used for low cost photonics applications. Also alternative optical materials can be used in the context of this photonics platform.

    With the robust design, the grating couplers result in improved yield and a more cost effective solution is realized for integration of the waveguides with the germanium and graphene photodetectors.

     

     

     

     

  • 8.
    A Monfared, Behzad
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Design and Construction of a Small Ammonia Heat Pump2010Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    In view of the fact that most of the synthetic refrigerants, in case of leakage or release, are harmful to the environment by contributing in global warming or depleting stratospheric ozone layer, many research works have been done recently to find alternative refrigerants posing no or negligible threat to the environment. Among alternative refrigerants, ammonia, a natural refrigerant with zero Global Warming Potential (GWP) and Ozone Depletion Potential (ODP), can be a sensible choice.Although ammonia has been used for many years in large industrial systems, its application in small units is rare. In this project a small heat pump with about 7 kW heating capacity at -5 °C and +40 °C evaporation and condensation temperatures is designed and built to work with ammonia as refrigerant. The heat pump is expected to produce enough heat to keep a single-family house warm in Sweden and to provide tap hot water for the house. After successful completion of this project, it is planned to install the heat pump in a house to test it throughout a heating season to study its performance in real working conditions.Since ammonia is flammable and toxic in high concentrations, the refrigerant charge is tried to be kept low in the heat pump to reduce the risk of fire or poisoning in case of unwanted release of refrigerant to the surroundings. The compact design of the heat pump helps reducing the refrigerant charge. Besides, considering the limited space normally reserved for installation of a heat pump in a house, the compact design of the heat pump is necessary.

  • 9.
    A Monfared, Behzad
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Palm, Björn
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Corrigendum to “Optimization of layered regenerator of a magnetic refrigeration device” (International Journal of Refrigeration (2015) 57 (103–111)(S0140700715001267)(10.1016/j.ijrefrig.2015.04.019))2017Ingår i: International journal of refrigeration, ISSN 0140-7007, E-ISSN 1879-2081, Vol. 78Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The authors regret that, in three instances on page 105 the term “Maxwell equations” is used mistakenly instead of “thermodynamic relations”. However, this does not affect any results or conclusions and is just a correction in the terminology. The authors would like to apologise for any inconvenience caused.

  • 10. A, Ometov
    et al.
    A, Orsino
    L, Militano
    D, Moltchanov
    G, Araniti
    E, Olshannikova
    G, Fodor
    S, Andreev
    T, Olsson
    A, Iera
    J, Torsner
    Y, Koucheryavy
    T, Mikkonen
    Toward trusted, social-aware D2D connectivity: Bridging across the technology and sociality realms2016Ingår i: IEEE wireless communications, ISSN 1536-1284, E-ISSN 1558-0687, Vol. 23, nr 4, 103-111 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Driven by the unprecedented increase of mobile data traffic, D2D communications technology is rapidly moving into the mainstream of the 5G networking landscape. While D2D connectivity originally emerged as a technology enabler for public safety services, it is likely to remain at the heart of the 5G ecosystem by spawning a wide diversity of proximate applications and services. In this work, we argue that the widespread adoption of the direct communications paradigm is unlikely without embracing the concepts of trust and social-aware cooperation between end users and network operators. However, such adoption remains conditional on identifying adequate incentives that engage humans and their connected devices in a plethora of collective activities. To this end, the mission of our research is to advance the vision of social-aware and trusted D2D connectivity, as well as to facilitate its further adoption. We begin by reviewing the various types of underlying incentives with the emphasis on sociality and trust, discuss these factors specifically for humans and for networked devices (machines), and also propose a novel framework allowing construction of much needed incentive-aware D2D applications. Our supportive system-level performance evaluations suggest that trusted and social-aware direct connectivity has the potential to decisively augment network performance. We conclude by outlining the future perspectives of its development across the research and standardization sectors.

  • 11.
    A. Taher, Ali
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsteknik.
    BIM Software Capability and Interoperability Analysis: An analytical approach toward structural usage of BIM software (S-BIM)2016Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    This study focused on the structuralanalysis of BIM models. Different commercial software (Autodesk products and Rhinoceros)are presented through modelling and analysis of different structures with varying complexity,section properties, geometry, and material. Beside the commercial software, differentarchitectural and different tools for structural analysis are evaluated (dynamo, grasshopper,add-on tool, direct link, indirect link via IFC).

  • 12.
    A Österman, Sami
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Industriell produktion.
    Kumar, Shirish
    KTH, Skolan för industriell teknik och management (ITM), Industriell produktion.
    Vattenskärning: Teknologin och dess tillämpningsområden2010Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Vattenskärning anses generellt vara en mångsidig bearbetningsteknik med en mängd tillämpningsområden. Ren vattenskärning gör det möjligt att skära i mjuka material som gummi, medan tillsatt abrasivmedel tillåter skärning av bland annat stål och keramik. Skärningen lämnar inga restspänningar eller någon värmepåverkan i materialet. Dessutom blir ytfinheten så bra att man ofta slipper efterbehandling. Processen skapar inte heller några farliga gaser och är relativt miljövänlig. Syftet med detta arbete har varit att undersöka vattenskärningstekniken, dess nuvarande samt nya tillämpningsområden. Målet har även varit att jämföra tekniken med alternativa bearbetningsmetoder för att klargöra för‐ och nackdelar mellan dessa. Detta gjordes i syfte för att undersöka vilken teknik som är lämpligast att använda beroende på egenskaper såsom material, materialtjocklek och storlek av tillverkad serie. Arbetet har skrivits från Sverige och Frankrike och därmed har man valt att undersöka ifall användningsområdena hos vattenskärning skiljer sig mellan de två länderna. För att uppnå syftet valdes tre frågeställningar för att besvara hur man utökar tillämpningsområdet för vattenskärning, vilka för‐ respektive nackdelar vattenskärning har jämfört med andra skärmetoder och hur tillämpningsområdena är annorlunda mellan Frankrike och Sverige. De huvudsakliga informationskällorna för arbetet har varit intervjuer med tillverkande företag som använder sig av vattenskärning, leverantörer av vattenskärningsmaskiner och forskningsinstitut. Teoretisk komplettering har skett i form av informationssamling från litteratur och vetenskapliga artiklar. Valda primärkällor är företagshemsidor hos aktörer inom bearbetningsindustrin. Rapporten visar att vattenskärningstekniken är applicerbar inom ett flertal industrier och att tillämpningsområdena skiljer sig mellan Frankrike och Sverige; i Frankrike används vattenskärning främst inom livsmedelsindustrin, medan den är mer utbredd inom verkstadsindustrin i Sverige. Aktörer på den svenska marknaden är skeptiska till användning av vattentryck på över 400 MPa, trots att det tyder på många fördelar. Den huvudsakliga begränsningen hos vattenskärning är tjockleken hos materialet. Vid skärning av stål över 30 mm kan strålen fördröjas och resultera i en ickeprecis skärning, ett problem som löses genom att ändra skärparametrar såsom skärhastighet eller genom snedställning av skärmunstycket. Efter en utvärdering av plasma‐, laser‐ och vattenskärning, kan man konstatera att ingen metod är direkt konkurrerande med en annan, då varje teknik lämpar sig bäst inom sitt respektive användningsområde. Teknikerna kompletterar snarare än konkurrerar med varandra.

  • 13.
    Aagaard Fransson, Erik Johannes
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Wall-Horgen, Tobias
    KTH, Skolan för elektro- och systemteknik (EES), Elektroteknisk teori och konstruktion.
    Building and Evaluating a 3D Scanning System for Measurementsand Estimation of Antennas and Propagation Channels2012Självständigt arbete på avancerad nivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Wireless communications rely, among other things, on theunderstanding of the properties of the radio propagationchannel, the antennas and their interplay. Adequate measurementsare required to verify theoretical models and togain knowledge of the channel behavior and antenna performance.As a result of this master thesis we built a 3D fieldscanner measurement system to predict multipath propagationand to measure antenna characteristics. The 3Dscanner allows measuring a signal at the point of interestalong a line, on a surface or within a volume in space. In orderto evaluate the system, we have performed narrowbandchannel sounding measurements of the spatial distributionof waves impinging at an imaginary spherical sector. Datawas used to estimate the Angle-of-Arrivals (AoA) and amplitudeof the waves. An estimation method is presented tosolve the resulting inverse problem by means of regularizationwith truncated singular value decomposition. The regularizedsolution was then further improved with the helpof a successive interference cancellation algorithm. Beforeapplying the method to measurement data, it was testedon synthetic data to evaluate its performance as a functionof the noise level and the number of impinging waves. Inorder to minimize estimation errors it was also required tofind the phase center of the horn antenna used in the channelmeasurements. The task was accomplished by directmeasurements and by the regularization method, both resultsbeing in good agreement.

  • 14.
    Aagah, Orod
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Bro- och stålbyggnad.
    Aryannejad, Siavash
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Bro- och stålbyggnad.
    Dynamic analysis of soil-steel composite railway bridges: FE-modeling in Plaxis2014Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    A soil-steel composite bridge is a structure comprised of corrugated steel plates, which are joined with bolted connections, enclosed in friction soil material on both sides and on the top. The surrounding friction soil material, or backfill, is applied in sequential steps, each step involving compaction of the soil, which is a necessity for the construction to accumulate the required bearing capacity. Soil-steel composite bridges are an attractive option as compared with other more customary bridge types, owing to the lower construction time and building cost involved. This is particularly true in cases where gaps in the form of minor watercourses, roads or railways must be bridged.

    The objective of this master thesis is the modelling of an existing soil-steel composite railway bridge in Märsta, Sweden with the finite element software Plaxis. A 3D model is created and calibrated for crown deflection against measurement data collected by the Division of Structural Engineering and Bridges of the Royal Institute of Technology (KTH) in Stockholm, Sweden.

    Once the 3D model is calibrated for deflection, two 2D models with different properties are created in much the same way. In model 1, the full axle load is used and the soil stiffness varied, and in model 2 the soil stiffness acquired in the 3D model is used and the external load varied. The results are compared to measurement data. In 2D model 1 an efficient width of 1,46 m for the soil stiffness is used in combination with the full axle load, and in 2D model 2 an efficient width of 2,85 m is used for the external load, in combination with the soil stiffness acquired in the 3D model.

    Aside from this, parametric studies are performed in order to analyse the effect of certain input parameters upon output results, and in order to analyse influence line lengths.

    Recreating the accelerations and stresses in the existing bridge using finite element models is complicated, and the results reflect this. Below are shown the discrepancies between model results and measurement data for the pipe crown. The scatter in the measurement data has not been taken into consideration for this; these specific numbers are valid only for one particular train passage.

    For crown deflection, the 3D model shows a discrepancy of 4%, 2D model 1 5% and 2D model 2 8% compared with measurement data. For crown acceleration, in the same order, the discrepancy with measurements is 1%, 71% and 21% for maximum acceleration, and 46%, 35% and 28% for minimum acceleration. For maximum crown tensile stress, the discrepancy is 95%, 263% and 13%. For maximum crown compressive stress, the discrepancy is 70%, 16% and 46%.

  • 15.
    Aagah, Orod
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap.
    Kardan, Caesar
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap.
    Ett tillgängligt och användarvänligt boende: Anpassningsmöjligheter för människor med rörelsehinder och nedsatt rörelseförmåga2012Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    In this paper we have theoretically built a house designed for people with impaired mobility. The

    essay begins with an introduction in which the purpose of the work, the methodology and the

    depth-research part is presented. Then the layout that explains how we intend to adapt the house

    for the demands detailed in the depth-research part is presented. In the same chapter various

    structural components, such as different floors and walls, are specified.

    In the selection of materials we have taken into account the criteria of our specialization and

    adaptation to the aesthetic aspects, where we evaluate materials based upon our wishes regarding

    technique and form. There are also other aspects that are important in the selection of materials,

    including that these are adapted to technical traits of the construction elements and installations.

    In a later chapter the technical installations such as ventilation systems, heating systems,

    electricity and sanitation are presented, where both technical and financial aspects are described

    in detail. The economic aspects are also described in connection with calculating the building's

    power and energy requirements and then presented in the section where costs are accounted for.

    Finally, the work is summarized in the section “Conclusion and Discussion” in which we analyze

    all the work, and based on these analyses conclusions are drawn. During the course of work

    regulations such as Boverkets Byggregler (BBR) and other sources were used. These sources are

    presented in the bibliography section. We also received help and guidance from our supervisors

    in various parts of the work, which we are grateful for.

  • 16.
    Aalto, Jonatan
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Betongbyggnad.
    Neuman, Elisabeth
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Betongbyggnad.
    Comparison of Punching Shear Design Provisions for Flat Slabs2017Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Abstract

    A new generation of EN 1992-1-1 (2004) also known as Eurocode 2 is under development

    and currently there is a set of proposed provisions regarding section 6.4

    about punching shear, PT1prEN 1992-1-1(2017). It was of interest to compare the

    proposal with the current punching shear design provisions.

    The aim of this master thesis was to compare the punching shear resistance obtained

    in accordance with both design codes. Furthermore the eect of some parameters

    on the resistance was to be compared. It was also of interest to evaluate the userfriendliness

    of the proposal.

    In order to meet the aim, a case study of a real  at slab with drop panels was performed

    together with a parametric study of a pure ctive  at slab. The parametric

    study was performed for inner, edge and corner columns in the cases prestressed,

    without and with shear reinforcement.

    It was concluded that the distance

    av from the column axis to the contra  exural

    location has a big in uence on the punching shear resistance. The factor

    ddg

    considering concrete type and aggregate properties also has a big impact on the resistance.

    The simplied estimation of

    av according to 6.4.3(2) in PT1prEN 1992-1-1

    (2017) may be inaccurate in some cases.

    The length

    b0 of the control perimeter has a larger eect on the resistance in EN

    1992-1-1 (2004) than in PT1prEN 1992-1-1 (2017).

    In PT1prEN 1992-1-1 (2017), studs located outside the second row has no impact

    on the resistance.

    The tensioning force in a prestressed  at slab has a larger in uence on the resistance

    in PT1prEN 1992-1-1 (2017) than in EN 1992-1-1 (2004). Furthermore,

    the reinforcement ratio is increased by the tendons, and thus aect the resistance in

    PT1prEN 1992-1-1 (2017).

    Clearer provisions for the denition of the support strip

    bs for corners and ends

    of walls are needed in PT1prEN 1992-1-1 (2017).

    It may be questionable if the reduction of the perimeter for a large supported area in

    accordance with 6.4.2(4) in PT1prEN 1992-1-1 (2017) underestimates the resistance

    v

    in some cases.

    Considering the work-load with PT1prEN 1992-1-1 (2017), more parameters are

    included. However, they may not require that much eort to obtain.

    Keywords: Punching shear, resistance, concrete,  at slab, design provisions, Eurocode

    2, case study, parametric study, shear reinforcement, prestressed

    vi

  • 17.
    Aaman, Sophia
    et al.
    KTH, Skolan för industriell teknik och management (ITM).
    Hessel Lundberg, Johan Henrik
    KTH, Skolan för industriell teknik och management (ITM).
    Setting the seeds for a green growth -A Study of biofuel development in Indonesia’s transport sector2017Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
  • 18.
    Aare, Magnus
    et al.
    KTH, Skolan för teknik och hälsa (STH), Neuronik (Stängd 20130701).
    Kleiven, Svein
    KTH, Skolan för teknik och hälsa (STH), Neuronik (Stängd 20130701).
    Evaluation of head response to ballistic helmet impacts, using FEM2003Konferensbidrag (Refereegranskat)
  • 19.
    Aare, Magnus
    et al.
    KTH, Tidigare Institutioner, Farkost- och flygteknik.
    Kleiven, Svein
    KTH, Tidigare Institutioner, Farkost- och flygteknik.
    Halldin, Peter
    KTH, Tidigare Institutioner, Farkost- och flygteknik.
    Injury tolerances for oblique impact helmet testing2004Ingår i: International Journal of Crashworthiness, ISSN 1358-8265, E-ISSN 1754-2111, Vol. 9, nr 1, 15-23 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The most frequently sustained severe injuries in motorcycle crashes are injuries to the head, and many of these are caused by rotational force. Rotational force is most commonly the result of oblique impacts to the head. Good testing methods for evaluating the effects of such impacts are currently lacking. There is also a need for improving our understanding of the effects of oblique impacts on the human head. Helmet standards currently in use today do not measure rotational effects in test dummy heads. However rotational force to the head results in large shear strains arising in the brain, which has been proposed as a cause of traumatic brain injuries like diffuse axonal injuries (DAI). This paper investigates a number of well-defined impacts, simulated using a detailed finite element (FE) model of the human head, an FE model of the Hybrid III dummy head and an FE model of a helmet. The same simulations were performed on both the FE human head model and the FE Hybrid III head model, both fitted with helmets. Simulations on both these heads were performed to describe the relationship between load levels in the FE Hybrid III head model and strains in the brain tissue in the FE human head model. In this study, the change in rotational velocity and the head injury criterion (HIC) value were chosen as appropriate measurements. It was concluded that both rotational and translational effects are important when predicting the strain levels in the human brain.

  • 20.
    Aare, Magnus
    et al.
    KTH, Skolan för teknik och hälsa (STH), Neuronik (Stängd 20130701).
    Kleiven, Svein
    KTH, Skolan för teknik och hälsa (STH), Neuronik (Stängd 20130701).
    Halldin, Peter
    KTH, Skolan för teknik och hälsa (STH), Neuronik (Stängd 20130701).
    Proposed global injury thresholds for oblique helmet impacts2003Konferensbidrag (Refereegranskat)
  • 21.
    Aarno, Daniel
    et al.
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP. KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS.
    Ekvall, Staffan
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP. KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS.
    Kragic, Danica
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP. KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS.
    Adaptive virtual fixtures for machine-assisted teleoperation tasks2005Ingår i: 2005 IEEE International Conference on Robotics and Automation (ICRA), Vols 1-4, 2005, 1139-1144 s.Konferensbidrag (Refereegranskat)
    Abstract [en]

    It has been demonstrated in a number of robotic areas how the use of virtual fixtures improves task performance both in terms of execution time and overall precision, [1]. However, the fixtures are typically inflexible, resulting in a degraded performance in cases of unexpected obstacles or incorrect fixture models. In this paper, we propose the use of adaptive virtual fixtures that enable us to cope with the above problems. A teleoperative or human machine collaborative setting is assumed with the core idea of dividing the task, that the operator is executing, into several subtasks. The operator may remain in each of these subtasks as long as necessary and switch freely between them. Hence, rather than executing a predefined plan, the operator has the ability to avoid unforeseen obstacles and deviate from the model. In our system, the probability that the user is following a certain trajectory (subtask) is estimated and used to automatically adjusts the compliance. Thus, an on-line decision of how to fixture the movement is provided.

  • 22.
    Aarno, Daniel
    et al.
    KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS. KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP.
    Kragic, Danica
    KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS. KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP.
    Layered HMM for motion intention recognition2006Ingår i: 2006 IEEE/RSJ International Conference on Intelligent Robots and Systems, Vols 1-12, NEW YORK: IEEE , 2006, 5130-5135 s.Konferensbidrag (Refereegranskat)
    Abstract [en]

    Acquiring, representing and modeling human skins is one of the key research areas in teleoperation, programming. by-demonstration and human-machine collaborative settings. One of the common approaches is to divide the task that the operator is executing into several subtasks in order to provide manageable modeling. In this paper we consider the use of a Layered Hidden Markov Model (LHMM) to model human skills. We evaluate a gestem classifier that classifies motions into basic action-primitives, or gestems. The gestem classifiers are then used in a LHMM to model a simulated teleoperated task. We investigate the online and offline classilication performance with respect to noise, number of gestems, type of HAIM and the available number of training sequences. We also apply the LHMM to data recorded during the execution of a trajectory-tracking task in 2D and 3D with a robotic manipulator in order to give qualitative as well as quantitative results for the proposed approach. The results indicate that the LHMM is suitable for modeling teleoperative trajectory-tracking tasks and that the difference in classification performance between one and multi dimensional HMMs for gestem classification is small. It can also be seen that the LHMM is robust w.r.t misclassifications in the underlying gestem classifiers.

  • 23.
    Aarno, Daniel
    et al.
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP. KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS.
    Kragic, Danica
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP. KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS.
    Motion intention recognition in robot assisted applications2008Ingår i: Robotics and Autonomous Systems, ISSN 0921-8890, E-ISSN 1872-793X, Vol. 56, nr 8, 692-705 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Acquiring, representing and modelling human skills is one of the key research areas in teleoperation, programming-by-demonstration and human-machine collaborative settings. The problems are challenging mainly because of the lack of a general mathematical model to describe human skills. One of the common approaches is to divide the task that the operator is executing into several subtasks or low-level subsystems in order to provide manageable modelling. In this paper we consider the use of a Layered Hidden Markov Model (LHMM) to model human skills. We evaluate a gesteme classifier that classifies motions into basic action-primitives, or gestemes. The gesteme classifiers are then used in a LHMM to model a teleoperated task. The proposed methodology uses three different HMM models at the gesteme level: one-dimensional HMM, multi-dimensional HMM and multidimensional HMM with Fourier transform. The online and off-line classification performance of these three models is evaluated with respect to the number of gestemes, the influence of the number of training samples, the effect of noise and the effect of the number of observation symbols. We also apply the LHMM to data recorded during the execution of a trajectory tracking task in 2D and 3D with a mobile manipulator in order to provide qualitative as well as quantitative results for the proposed approach. The results indicate that the LHMM is suitable for modelling teleoperative trajectory-tracking tasks and that the difference in classification performance between one and multidimensional HMMs for gesteme classification is small. It can also be seen that the LHMM is robust with respect to misclassifications in the underlying gesteme classifiers.

  • 24.
    Aarno, Daniel
    et al.
    KTH, Tidigare Institutioner, Numerisk analys och datalogi, NADA.
    Kragic, Danica
    KTH, Tidigare Institutioner, Numerisk analys och datalogi, NADA.
    Christensen, Henrik
    KTH, Tidigare Institutioner, Numerisk analys och datalogi, NADA.
    Artificial potential biased probabilistic roadmap method2004Ingår i: 2004 IEEE INTERNATIONAL CONFERENCE ON ROBOTICS AND AUTOMATION, VOLS 1- 5, PROCEEDINGS, 2004, 461-466 s.Konferensbidrag (Refereegranskat)
    Abstract [en]

    Probabilistic roadmap methods (PRMs) have been successfully used to solve difficult path planning problems but their efficiency is limited when the free space contains narrow passages through which the robot must pass. This paper presents a new sampling scheme that aims to increase the probability of finding paths through narrow passages. Here, a biased sampling scheme is used to increase the distribution of nodes in narrow regions of the free space. A partial computation of the artificial potential field is used to bias the distribution of nodes.

  • 25.
    Aarno, Daniel
    et al.
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP. KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS.
    Lingelbach, F.
    Kragic, Danica
    KTH, Skolan för datavetenskap och kommunikation (CSC), Datorseende och robotik, CVAP. KTH, Skolan för datavetenskap och kommunikation (CSC), Centra, Centrum för Autonoma System, CAS.
    Constrained path planning and task-consistent path adaptation for mobile manipulators2005Ingår i: 2005 12th International Conference on Advanced Robotics, 2005, 268-273 s.Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents our ongoing research in the design of a versatile service robot capable of operating in a home or office environment. Ideas presented here cover architectural issues and possible applications for such a robot system with focus on tasks requiring constrained end-effector motions. Two key components of such system is a path planner and a reactive behavior capable of force relaxation and path adaptation. These components are presented in detail along with an overview of the software architecture they fit into.

  • 26.
    Aas, Steffen
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Fastigheter och byggande.
    Hillestad, Thomas
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Fastigheter och byggande.
    Verdivurdering av næringseiendom - hva brukes av aktørene i markedet?: - Er det behov for en verdivurderingsstandard i det norske markedet? 2015Självständigt arbete på avancerad nivå (magisterexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
  • 27.
    Aassi, Adil
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap, Väg- och banteknik.
    Drift och underhåll för högre effektivitet av järnvägar.2012Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Den senaste svenska vintern var en riktig katastrof som bestod av Ovanliga mängder snö, fukt och kyla, från mitten av december 2009 till mitten av mars 2010. Snömassor orsakade stora problem i tågtrafiken, både nationellt och lokalt. Det påverkade både gods- och persontransporten. Halka och tak ras ledde till personskador och dödsolyckor. Kylan påverkade även elnät som ledde till att människor stod utan värme och belysning. Allmänheten drabbades av snöovädret på olika sätt. Människor skadades i trafiken, halkolyckor, och flera tak som rasade ner. Människor kom även försent till olika destinationer. I södra och mellersta Sverige var problemet störst inom området transport (väg, järnväg). Störningar i vatten, elförsörjningen och tak ras. I söder uppstod ett kontaktledningsfel med flera växel- och signalproblem.

    En viktig sak är att det inte går att tänka att den vintern bara var en engångsföreteelse, utan Trafikverket måste tänka på att Sverige ligger i Norden och att vintern 2009/10 kan upprepas flera gånger. Därför är det viktigt att bygga en modell för underhållet. Trafikverket skulle kunna ta de sista vintrarna på allvar och ta fram en åtgärdsplan för att minska effekterna av framtida, svåra vinterförhållanden.

    Avhjälpande åtgärder måste då sättas in snabbt för att förhindra störningar i trafiken. Mången tågtrafik störningar beror på fel i någon eller några komponenter som själva baninfrastrukturen består av. En jämförelse har gjorts mellan spårväxlar under sommaren och spårväxlar under vintrar, som visar 85 % fler fel under vintertid än sommartid. Trafikverkets kostnader för underhåll av järnvägar på lång sikt uppgår till 4 miljarder. Regeringen fastställde den nya nationella trafikplanen för utveckling av transportsystemet för perioden 2010-2021 i slutet av mars 2010. I arbetet undersöks en jämförelse, så kallad "Benchmarking" mellan Sverige och Schweiz som visar hög kvalitet i kapacitetsutnyttjande och hög punktlighet i Schweiz. Punktlighet i Schweiz har stigit 97 % medan i Sverige var 87 %.

    Ett övergripande syfte med arbetet är att undersöka hur effektiviteten på det svenska järnvägs nätet kan förbättras genom att studera framgångarna i Schweiz.

  • 28.
    Abacar, Armando
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Optimization of Maputo Power Plant2013Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The Electricidade de Moçambique, E.P. (EDM) is the power utility in Mozambique, responsible to generate, transport and distribute electricity all over the country. The company has three gas turbines installed at Maputo Power Plant. All units burn diesel oil and are used only for back up. Currently only the unit #2 is available for operation.

    The main constraint that EDM faces is the high operation costs due to diesel price. Hence the company is considering converting units #2 and #3 to burn natural gas, resource available locally. The country is currently exporting natural gas to the neighbouring Republic of South Africa.

    This MSc thesis project calculates the power output of all gas turbines when burning natural gas and optimizes the power plant capacity by proposing modifications of the current power turbine cycles to allow sustainable operation

  • 29.
    Abad Caballero, Israel Manuel
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Secure Mobile Voice over IP2003Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Voice over IP (VoIP) kan defineras som förmågan att göra ett telefonsamtal och att skicka fax (eller att göraallting som man idag kan göra över det publika telefonnätet) över ett IP−baserat nätverk med en passande kvalitet och till lägre kostnad, alternativt större nytta.

    VoIP måste tillhandahållas med nödvändiga säkerhetstjänster utan att teknikens prestanta påverkas. Detta blir allt viktigare när VoIP används över trådlösa länktekniker (såsom trådlösa lokala nätverk, WLAN), givet dessa länkars begränsade bandbredd och den bearbetningkraft som krävs för att exekvera säkerhetsmekanismerna. Vi måste tänka på VoIPs säkerhet likt en kedja där inte någon länk, från säker uppkoppling till säker nedkoppling, får fallera för att erhålla en säker process. I detta dokument presenteras en lösning på detta problem och innefattar en säker modell för Mobile VoIP som minimerar bearbetningskostnaderna och bandbreddsutnyttjandet. Detta erhålls huvudsakligen genom utnyttjande av säkerhetsprotokoll med hög genomströmning och låg paketexpansion, såsom "Secure Real− time Protocol" (SRTP), och av krypteringsprotokoll med hög hastighet, såsom "Advanced Encryption Standard" (AES).

    I detta dokument beskriver jag problemet och dess alternativa lösningar. Jag beskriver också den valda lösningen och dess protokoll och mekanismer mer detaljerat, till exempel "Transport Layer Security" (TLS) för att säkra "Session Initiation Protocol" (SIP), SRTP för att skydda transporten av data och "Multimedia Internet KEYing" (MIKEY) för nyckelhantering. En implementation av SRTP, kallad MINIsrtp, finns också beskriven.

    Beträffande praktiskt arbete och tester av lösningsmodellen har detta projekt fokuserats på skyddandet av datatransporten (SRTP), dess implementation och prestanda. Emellertid har en grundlig teoretisk undersökning genomförts, vilken innefattar andra aspekter såsom telefonsamtalets uppkoppling och nedkoppling (med hjälp av SIP) och valet av passande nyckelhanteringsprotokoll (MIKEY) för att stödja SRTP.

  • 30.
    Abad Camarero, Daniel
    KTH, Skolan för elektro- och systemteknik (EES), Kommunikationsnät.
    Performance analysis of IPv4 / IPv6 protocols over the third generation mobile network2014Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Currently, the IPv4 protocol is heavily used by institutions, companies and individuals, but every day there is a higher number of devices connected to the network such as home appliances, mobile phones or tablets. Each machine or device needs to have its own IP address to communicate with other machines connected to Internet. This implies the need for multiple IP addresses for a single user and the current protocol begins to show some deficiencies due to IPv4 address space exhaustion. Therefore, for several years experts have been working on an IP protocol update: the IPv6 128-bit version can address up to about 340 quadrillion system devices concurrently. With IPv6, today, every person on the planet could have millions of devices simultaneously connected to the Internet.

    The choice of the IP protocol version affects the performance of the UMTS mobile network and the browsers as well. The aim of the project is to measure how the IPv6 protocol performs compared to the previous IPv4 protocol. It is expected that the IPv6 protocol generates a smaller amount of signalling and less time is required to fully load a web page. We have analysed some KPIs (IP data, signalling, web load time and battery) in lab environment using Smartphones, to observe the behaviour of both, the network and the device.  The main conclusion of the thesis is that IPv6 really behaves as expected and generates savings in signalling, although the IP data generated is larger due to the size of the headers. However, there is still much work as only the most important webpages and the applications with a high level of market penetration operate well over the IPv6 protocol.

  • 31. Abadal, Sergi
    et al.
    Alarcon, Eduard
    Cabellos-Aparicio, Albert
    Lemme, Max C.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
    Nemirovsky, Mario
    Graphene-Enabled Wireless Communication for Massive Multicore Architectures2013Ingår i: IEEE Communications Magazine, ISSN 0163-6804, E-ISSN 1558-1896, Vol. 51, nr 11, 137-143 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Current trends in microprocessor architecture design are leading towards a dramatic increase of core-level parallelization, wherein a given number of independent processors or cores are interconnected. Since the main bottleneck is foreseen to migrate from computation to communication, efficient and scalable means of inter-core communication are crucial for guaranteeing steady performance improvements in many-core processors. As the number of cores grows, it remains unclear whether initial proposals, such as the Network-on-Chip (NoC) paradigm, will meet the stringent requirements of this scenario. This position paper presents a new research area where massive multicore architectures have wireless communication capabilities at the core level. This goal is feasible by using graphene-based planar antennas, which can radiate signals at the Terahertz band while utilizing lower chip area than its metallic counterparts. To the best of our knowledge, this is the first work that discusses the utilization of graphene-enabled wireless communication for massive multicore processors. Such wireless systems enable broadcasting, multicasting, all-to-all communication, as well as significantly reduce many of the issues present in massively multicore environments, such as data coherency, consistency, synchronization and communication problems. Several open research challenges are pointed out related to implementation, communications and multicore architectures, which pave the way for future research in this multidisciplinary area.

  • 32.
    Abaid, Mohammed
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik.
    Evaluation of Jatropha Curcas as future en-ergy crop in some African countries.2015Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Biofuels now days consider as one of the successful alternative to meet the challenges associated with climate change and peak oil, as well as a way for poorer countries to develop an industry in order to enhance social and economic development. In many developing countries and particularly in Africa, this has led to large-scale investments in lands by foreign companies, and as a consequence there has been a debate on whether these actions are environmentally sustainable and whether this kind of activity actually brings economic development. The investments of biofuels in Africa, espe-cially the Jatropha plantations are debatable. Several arguments have been concentrat-ed on development goals, economic issues and environmental concerns. This report evaluates the status of some Jatropha projects in Sudan, Ethiopia, Kenya and Tanza-nia, the outcomes of the report show that biofuels from Jatropha lead to a significant socio -economic benefits by creating many jobs opportunities and improve the stand-ard of living in Africa. However, inadequate funding’s, high investment costs, no clear policies for biodiesel are the most challenging for Jatropha in Africa which need fur-ther mechanisms and ideology by African scientists, leaders, NGOs, farmers and deci-sion makers. In the studied countries, it was reported that the Jatropha produce low yields of oil seeds especially in the marginal lands with no enough water supplies. In Kenya the productivity of Jatropha is very low for large scale- project. Moreover some social and environmental impacts are also seen for Jatropha cultivations in Ethiopia, Kenya and Tanzania. Some Jatropha projects have impacted the food security nega-tively; nevertheless some biofuels experts believe that Jatropha has no any adverse im-pacts on food security since it is inedible and grown on marginal lands. In Ethiopia, the main environmental impacts of Jatropha are related to biodiversity, water quality and quantity. In Kenya, the environmental impacts are related to biodiversity, carbon emissions, water withdrawal, pollution of agro- chemicals usage, deforestation and soil erosion, whereas in Tanzania, the main environmental issues are connected to the change of land use system, impacts on biodiversity and impacts on water resources.

  • 33.
    Abaris, Nedas
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Fastigheter och byggande.
    Sjönoce, Firass
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Fastigheter och byggande.
    Investors and valuers: Similarities and differences from a behavioural perspective2014Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    This thesis is an explorative analysis of the commercial real estate actors. The behavioral theory has revealed many flaws in the neo classical assumptions. This includes models of rationality and prescribed behaviors. Research suggests both appraisers and investor act in ways that can be seen as irrational. Appraisers amongst other things anchor to figures that are not part of the valuation theory and investor invest on bases that are not fundamentally sound. Both also exhibit biases, such as confirmation bias and loss aversion. If valuation does not reflect the way market participants behave then they fail to give us a correct market value. We use interviews to try and understand how appraisers try to reflect the market and to understand how investors and other market actors value properties by comparing their use of the DCF-method. Our results suggest that there are many technical differences between how methods are used by different actors and that appraisers have a too close connection with the market actors.

  • 34.
    Abas, Riad Abdul
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Property measurements towards understanding process phenomena2005Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The main objective of this industrially important work was to gain an increasing understanding of the properties of materials such as CMSX-4 nickel base super alloy, mould powder used in continuous casting of steel and coke used in blast furnace, with special reference to the thermal diffusivities. The measurements were carried out in a wide temperature range, solid, liquid, glassy and crystalline states.

    For CMSX-4 alloy, the thermal conductivities were calculated from the experimental thermal diffusivities. Both the diffusivities and conductivities were found to increase with increasing temperature. Microscopic analysis showed the presence of intermetallic phases such as NiTi and NiTi2 below 1253 K. In this region, the mean free path of the phonons is likely to be limited by scattering against lattice defects. Between 1253 K and solidus temperature, these phases dissolved in the alloy adding to the impurities in the matrix, which, in turn, caused a decrease in the thermal diffusivity. This effect was confirmed by annealing the samples at 1573 K. The thermal diffusivities of the annealed samples measured at 1277, 1403 and 1531 K were found to be lower than the thermal diffusivities of non-annealed samples and the values did not show any noticeable change with time. It could be related to the attainment of equilibrium with the completion of the dissolution of γ and γ´ phases during the annealing process.

    Liquid CMSX-4 does not show any change of thermal diffusivity with temperature. It may be attributed to the decreasing the mean free path being shorter than characteristic distance between two neighbouring atoms.

    On the other hand thermal diffusivities of mould powder having glassy and crystalline states decrease with increasing temperature at lower temperature and are constant at higher temperature except for one glassy sample.

    Analogously, the thermal diffusivity measurements of mould powder did not show any significant change with temperature in liquid state. It is likely to be due to the silicate network being largely broken down.

    The thermal diffusivity is increased with increasing crystallisation degree of mould powder, which is expected from theoretical considerations.

    The coke sample, taken from deeper level of the blast furnace, is found to have larger thermal diffusivity. This could be correlated to the average crystallite size along the structural c-axis, Lc, which is indicative of the higher degree of graphitisation. This was also confirmed by XRD measurements of the different coke samples. The degree of graphitisation was found to increase with increasing temperature. Further, XRD measurements of coke samples taken from different levels in the shaft of the blast furnace show that the graphitisation of coke was instantaneous between room temperature and 1473 K.

  • 35. Abata, E.
    et al.
    Abdallah, J. M.
    Addy, T. N.
    Adragna, P.
    Aharrouche, M.
    Ahmad, A.
    Akesson, T. P. A.
    Aleksa, M.
    Alexa, C.
    Anderson, K.
    Anghinolfi, F.
    Antonaki, A.
    Arabidze, G.
    Arik, E.
    Baker, O. K.
    Banfi, D.
    Baron, S.
    Beck, H. P.
    Belhorma, B.
    Benchekroun, D.
    Benjamin, D. P.
    Benslama, K.
    Kuutmann, E. Bergeaas
    Bertelsen, H.
    Binet, S.
    Biscarat, C.
    Boldea, V.
    Bondarenko, V. G.
    Boonekamp, M.
    Bosman, M.
    Bourdarios, C.
    Chromek, D. Burckhart
    Bychkov, V.
    Callahan, J.
    Calvet, D.
    Canneri, M.
    Garrido, M. Capeans
    Caprini, M.
    Sas, L. Cardiel
    Carli, T.
    Carminati, L.
    Carvalho, J.
    Cascella, M.
    Castillo, M. V.
    Catinaccio, A.
    Sforza, M. Cavalli
    Cavalli, D.
    Cavasinni, V.
    Cetin, S. A.
    Chen, H.
    Cherkaoui, R.
    Chevallier, F.
    Ciobotaru, M.
    Citterio, M.
    Cleland, B.
    Cogneras, E.
    Muino, P. Conde
    Consonni, M.
    Constantinescu, S.
    Cornelissen, T.
    Radu, A. Corso
    Costa, G.
    Cwetanski, P.
    Da Silva, D.
    DAM, M.
    Danielsson, H. O.
    Dannheim, D.
    Davidek, T.
    De, K.
    Defay, P. O.
    Dekhissi, B.
    Del Peso, J.
    Delmastro, M.
    Del Prete, T.
    Derue, F.
    Di Ciaccio, L.
    Di Girolamo, B.
    Dita, S.
    Dittus, F.
    Djama, F.
    Djobava, T.
    Dobson, M.
    Dolgoshein, B. A.
    Dotti, A.
    Drake, G.
    Dressnandt, N.
    Driouchi, C.
    Ebenstein, W. L.
    Eerola, P.
    Efthymiopoulos, I.
    Egorov, K.
    Eifert, T. F.
    El Kacimi, M.
    Etienvre, A. I.
    Fabich, A.
    Fakhr-Edine, A. I.
    Fanti, M.
    Farbin, A.
    Farthouat, P.
    Fassouliotis, D.
    Fayard, L.
    Febbraro, R.
    Fedin, O. L.
    Fenyuk, A.
    Ferrari, R.
    Ferreira, B. C.
    Ferrer, A.
    Filippini, G.
    Fournier, D.
    Francavilla, P.
    Francis, D.
    Froeschl, R.
    Froidevaux, D.
    Fullana, E.
    Gadomski, S.
    Gagnon, P.
    Gameiro, S.
    Garcia, R.
    Ghodbane, N.
    Giakoumopoulou, V.
    Giangiobbe, V.
    Giokaris, N.
    Glonti, G.
    Gollub, N.
    Comes, A.
    Gomez, M. D.
    Gonzalez, V.
    Gorini, B.
    Goujdamiav, D.
    Grahn, K. J.
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Grenier, P.
    Grigalashvili, N.
    Grishkevich, Y.
    Gruwe, M.
    Guicheney, C.
    Gupta, A.
    Haeberli, C.
    Hajduk, Z.
    Hakobyan, H.
    Hance, M.
    Hansen, P. H.
    Harvey, A., Jr.
    Correia, A. Henriques
    Hervas, L.
    Higon, E.
    Hoffman, J.
    Hostachy, J. Y.
    Hruska, I.
    Hubaut, F.
    Hulsbergen, W.
    Hurwitz, M.
    Iconomidou-Fayard, L.
    Jen-La Plante, I.
    Johansson, P. D. C.
    Jon-And, K.
    Joos, M.
    Jorgensen, S.
    Kaczmarska, A.
    Kado, M.
    Karyukhin, A.
    Kataoka, M.
    Kayumov, F.
    Kazarov, A.
    Keener, P. T.
    Kekelidze, G. D.
    Kerschen, N.
    Khoriauli, G.
    Khramov, E.
    Khristachev, A.
    Khubua, J.
    Kittelmann, T. H.
    Klinkby, E.
    Koffas, T.
    Kolos, S.
    Konovalov, S. P.
    Kopikov, S.
    Korolkov, I.
    Kovalenko, S.
    Kowalski, T. Z.
    Kruger, K.
    Kramarenko, V.
    Kudin, L. G.
    Kulchitsky, Y.
    Lafaye, R.
    Univ Savoie, LAPP, CNTS IN2P3, Annecy Le Vieux, France.
    Laforge, B.
    Lampl, W.
    Lanni, F.
    Laplace, S.
    Le Bihan, A. C.
    Lechowski, M.
    Ledroit-Guillon, F.
    Lehmann, G.
    Leitner, R.
    Lelas, D.
    Liang, Z.
    Lichard, P.
    Lokajicek, M.
    Louchard, L.
    Loureiro, K.
    Lucotte, A.
    Luehring, F.
    Lundberg, B.
    Lund-Jensen, Bengt
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Ma, H.
    Mackeprang, R.
    Maio, A.
    Maleev, V. P.
    Malek, F.
    Maneira, J.
    Mandelli, L.
    Mazzanti, M.
    Manousakis, A.
    Mapelli, L.
    Marques, C.
    Martin, F.
    McFarlane, K. W.
    Mchedlidze, G.
    McPherson, R.
    Meirosu, C.
    Meng, Z.
    Miagkov, A.
    Mialkovski, V.
    Milstead, D.
    Minashvili, I.
    Mindur, B.
    Mitsou, V. A.
    Monnier, E.
    Morozov, S. V.
    Mosidze, M.
    Mouraviev, S. V.
    Munar, A.
    Nadtochi, A. V.
    Negri, A.
    Nemecek, S.
    Nessi, M.
    Nesterov, S. Y.
    Newcomer, F. M.
    Nikitine, I.
    Nikolic-Audit, I.
    Ogren, H.
    Oh, S. H.
    Oleshko, S. B.
    Olszowska, J.
    Onofre, A.
    Aranda, C. Padilla
    Paganis, S.
    Pallin, D.
    Pantea, D.
    Paolone, V.
    Parsons, J.
    Pasqualucci, E.
    Passmore, M. S.
    Patrichev, S.
    Peez, M.
    Reale, V. Perez
    Perini, L.
    Peshekhonov, V. D.
    Petersen, J.
    Petersen, T. C.
    Petti, R.
    Pilcher, J.
    Pina, J.
    Pinto, B.
    Podlyski, F.
    Poggioli, L.
    Poveda, J.
    Pralavorio, P.
    Pribyl, L.
    Price, M. J.
    Prieur, D.
    Puigdengoles, C.
    Puzo, P.
    Rajagopalan, S.
    Rembser, C.
    Ridel, M.
    Riu, I.
    Roda, C.
    Rohne, O.
    Romaniouk, A.
    Rousseau, D.
    Ruiz, A.
    Rusakovich, N.
    Rust, D.
    Ryabov, Y. F.
    Ryjov, V.
    Salto, O.
    Salvachua, B.
    Sanchis, E.
    Rios, C. Santamarina
    Santoni, C.
    Saraiva, J. G.
    Sarri, F.
    Sauvage, G.
    Says, L. P.
    Schaefer, M.
    Schegelsky, V. A.
    Schlager, G.
    Schlereth, J.
    Schmitt, C.
    Schwemling, P.
    Schwindling, J.
    Seixas, J. M.
    Seliverstov, D. M.
    Serin, L.
    Shalanda, N.
    Shin, T.
    Shmeleva, A.
    Silva, J.
    Simion, S.
    Simonyan, M.
    Sloper, J. E.
    Smirnov, S. Yu.
    Smirnova, L.
    Solans, C.
    Solodkov, A.
    Solovianov, O.
    Soloviev, I.
    Sosnovtsev, V. V.
    Spano, F.
    Speckmeyer, P.
    Stancu, S.
    Stanek, R.
    Starchenko, E.
    Straessner, A.
    Suchkov, S. I.
    Suk, M.
    Szczygiel, R. R.
    Tarrade, F.
    Tartarelli, F.
    Tas, P.
    Tayalati, Y.
    Teuscher, R.
    Thioye, M.
    Tikhomirov, V. O.
    Tisserant, S.
    Torres, J.
    Tremblet, L.
    Tsiareshka, P.
    Tsiskaridze, V.
    Unal, G.
    Unel, G.
    Usai, G.
    Valero, A.
    Valkar, S.
    Valls, J. A.
    Van Berg, R.
    Vandelli, W.
    Vannucci, F.
    Vartapetian, A.
    Vassilakopoulos, V. I.
    Vassilieva, L.
    Vazeille, F.
    Vetter-Cole, Y.
    Vichou, I.
    Vinogradov, V.
    Vivarelli, I.
    Volpi, M.
    Wang, C.
    Werner, P.
    Wheeler, S.
    Wiesmann, M.
    Wilkens, H.
    Williams, H. H.
    Wingerter-Seez, I.
    Yasu, Y.
    Zaitsev, A.
    Zenin, A.
    Zenis, T.
    Zenonos, Z.
    Zhang, H.
    Zhou, N.
    Study of energy response and resolution of the ATLAS barrel calorimeter to hadrons of energies from 20 to 350 GeV2010Ingår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 621, nr 1-3, 134-150 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A fully instrumented slice of the ATLAS detector was exposed to test beams from the SPS (Super Proton Synchrotron) at CERN in 2004. In this paper, the results of the measurements of the response of the barrel calorimeter to hadrons with energies in the range 20-350 GeV and beam impact points and angles corresponding to pseudo-rapidity values in the range 0.2-0.65 are reported. The results are compared to the predictions of a simulation program using the Geant 4 toolkit. (C) 2010 Published by Elsevier B.V.

  • 36. Abate, M.
    et al.
    De Jong, Gerard
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Centra, Centrum för transportstudier, CTS.
    The optimal shipment size and truck size choice - The allocation of trucks across hauls2014Ingår i: Transportation Research Part A: Policy and Practice, ISSN 0965-8564, E-ISSN 1879-2375, Vol. 59, 262-277 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    There has been a growing interest in understanding how firms allocate their trucks across hauls, and how this allocation changes under various economic environments. This study investigates how variations in route/haul, carrier and vehicle characteristics affect the optimal vehicle size choice and the associated choice of shipment size. We show that the two choices are derived from the same optimization problem. There can be a continuum of shipment sizes, but decision-makers in freight transport have to choose from a limited number of vehicle alternatives. Therefore, we use a discrete-continuous econometric model where shipment size is modeled as a continuous variable, and vehicle size/type choice as a discrete variable. The results indicate that when faced with higher demand, and during longer trips firms are more likely to use heavier vehicles and ship in larger quantities which suggest that firms are realizing economies of scale and economies of distance. The study also discusses the effect of vehicle operating cost on the vehicle selection process and its policy implications.

  • 37.
    Abayneh Alembo, Zinash
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap, Väg- och banteknik.
    User delay costs and uncertainty in the traffic forecast for road projects.2014Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    There are experimental based software packages as well as traffic simulation models that

    are used for analyzing life cycle cost of road projects. Among those our study was focused on

    currently available models to analyze the road user delay costs and to identify factors

    affecting road user delay costs. Sensitivity analyses were performed to identify the important

    factors that influence the user delay cost. Finally, prediction of future traffic demand as well

    as user delay cost, using the binomial lattice model, were presented to include the uncertainty

    of future traffic and user delay costs. The results of this study could help the highway

    designers with evaluating the future traffic.

  • 38. Abbas, Ghazanfar
    et al.
    Chaudhry, M. Ashraf
    Raza, Rizwan
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Singh, Manish
    Liu, Qinghua
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Qin, Haiying
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Zhu, Bin
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Study of CuNiZnGdCe-Nanocomposite Anode for Low Temperature SOFC2012Ingår i: Nanoscience and Nanotechnology Letters, ISSN 1941-4900, Vol. 4, nr 4, 389-393 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Composite electrodes of Cu0.16Ni0.27Zn0.37Ce0.16Gd0.04 (CNZGC) oxides have been successfully synthesized by solid state reaction method as anode material for low temperature solid oxide fuel cell (LTSOFC). These electrodes are characterized by XRD followed by sintering at various time periods and temperatures. Particle size of optimized composition was calculated 40-85 nm and sintered at 800 degrees C for 4 hours. Electrical conductivity of 4.14 S/cm was obtained at a temperature of 550 degrees C by the 4-prob DC method. The activation energy was calculated 4 x 10(-2) eV at 550 degrees C. Hydrogen was used as fuel and air as oxidant at anode and cathode sides respectively. I-V/I-P curves were obtained in the temperature range of 400-550 degrees C. The maximum power density was achieved for 570 mW/cm(2) at 550 degrees C.

  • 39.
    Abbas, Ghazanfar
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Raza, Rizwan
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Ashfaq, M.
    Chaudhry, M. Ashraf
    Khan, Ajmal
    Ahmad, Imran
    Zhu, Bin
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Electrochemical study of nanostructured electrode for low-temperature solid oxide fuel cell (LTSOFC)2014Ingår i: International journal of energy research (Print), ISSN 0363-907X, E-ISSN 1099-114X, Vol. 38, nr 4, 518-523 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Zn-based nanostructured Ba0.05Cu0.25Fe0.10Zn0.60O (BCFZ) oxide electrode material was synthesized by solid-state reaction for low-temperature solid oxide fuel cell. The cell was fabricated by sandwiching NK-CDC electrolyte between BCFZ electrodes by dry press technique, and its performance was assessed. The maximum power density of 741.87 mW-cm(-2) was achieved at 550 degrees C. The crystal structure and morphology were characterized by X-ray diffractometer (XRD) and SEM. The particle size was calculated to be 25 nm applying Scherer's formula from XRD data. Electronic conductivities were measured with the four-probe DC method under hydrogen and air atmosphere. AC Electrochemical Impedance Spectroscopy of the BCFZ oxide electrode was also measured in hydrogen atmosphere at 450 degrees C.

  • 40. Abbas, Ghazanfar
    et al.
    Raza, Rizwan
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi. COMSATS Institute of Information Technology, Pakistan .
    Chaudhry, M. A.
    Zhu, Bin
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Preparation and characterization of nanocomposite calcium doped ceria electrolyte with alkali carbonates (NK-CDC) for SOFC2010Ingår i: ASME 2010 8th International Conference on Fuel Cell Science, Engineering and Technology, FUELCELL 2010, ASME Press, 2010, 427-432 s.Konferensbidrag (Refereegranskat)
    Abstract [en]

    The entire world's challenge is to find out the renewable energy sources due to rapid depletion of fossil fuels because of their high consumption. Solid Oxide Fuel Cells (SOFCs) are believed to be the best alternative source which converts chemical energy into electricity without combustion. Nanostructured study is required to develop highly ionic conductive electrolyte for SOFCs. In this work, the calcium doped ceria (Ce0.8Ca0.2O 1.9) coated with 20% molar ratio of two alkali carbonates (CDC-M: MCO3, where M= Na and K) electrolyte was prepared by co-precipitation method in this study. Ni based electrode was used to fabricate the cell by dry pressing technique. The crystal structure and surface morphology was characterized by X-Ray Diffractometer (XRD), Scanning Electron Microscopy (SEM) and High Resolution Transmission Electron Microscopy (HRTEM). The particle size was calculated in the range of 10-20nm by Scherrer's formula and compared with SEM and TEM results. The ionic conductivity was measured by using AC Electrochemical Impedance Spectroscopy (EIS) method. The activation energy was also evaluated. The performance of the cell was measured 0.567W/cm2 at temperature 550°C with hydrogen as a fuel.

  • 41.
    Abbas, Ghazanfar
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Raza, Rizwan
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Chaudhry, M. Ashraf
    Zhu, Bin
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Preparation and Characterization of Nanocomposite Calcium Doped Ceria Electrolyte With Alkali Carbonates (NK-CDC) for SOFC2011Ingår i: Journal of Fuel Cell Science and Technology, ISSN 1550-624X, Vol. 8, nr 4, 041013- s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The entire world's challenge is to find out the renewable energy sources due to rapid depletion of fossil fuels because of their high consumption. Solid oxide fuel cells (SOFCs) are believed to be the best alternative source, which converts chemical energy into electricity without combustion. Nanostructure study is required to develop highly ionic conductive electrolytes for SOFCs. In this work, the calcium doped ceria (Ce0.8Ca0.2O1.9) coated with 20% molar ratio of two alkali carbonates (CDC-M: MCO3, where M = Na and K) electrolyte was prepared by coprecipitation method. Ni based electrode was used to fabricate the cell by dry pressing technique. The crystal structure and surface morphology were characterized by an X-ray diffractometer, scanning electron microscopy (SEM), and high resolution transmission electron microscopy (TEM). The particle size was calculated in the range 10-20 nm by Scherer's formula and compared with SEM and TEM results. The ionic conductivity was measured by using ac electrochemical impedance spectroscopy method. The activation energy was also evaluated. The performance of the cell was measured 0.567 W/cm(2) at temperature 550 degrees C with hydrogen as a fuel.

  • 42.
    Abbas, Ghazanfar
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi. COMSATS Institute of Information Technology, Pakistan.
    Raza, Rizwan
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi. COMSATS Institute of Information Technology, Pakistan.
    Khan, M. Ajmal
    Ahmad, Imran
    Chaudhry, M. Ashraf
    Sherazi, Tauqir A.
    Mohsin, Munazza
    Ahmad, Mukhtar
    Zhu, Bin
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Synthesize and characterization of nanocomposite anodes for low temperature solid oxide fuel cell2015Ingår i: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 40, nr 1, 891-897 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Solid oxide fuel cells have much capability to become an economical alternative energy conversion technology having appropriate materials that can be operated at comparatively low temperature in the range of 400-600 degrees C. The nano-scale engineering has been incorporated to improve the catalytic activity of anode materials for solid oxide fuel cells. Nanostructured Al0.10NixZn0.90-xO oxides were prepared by solid state reaction, which were then mixed with the prepared Gadolinium doped Ceria GDC electrolyte. The crystal structure and surface morphology were characterized by XRD and SEM. The particle size was evaluated by XRD data and found in the range of 20-50 nm, which was then ensured by SEM pictures. The pellets of 13 mm diameter were pressed by dry press technique and electrical conductivities (DC and AC) were determined by four probe techniques and the values have been found to be 10.84 and 4.88 S/cm, respectively at hydrogen atmosphere in the temperature range of 300-600 degrees C. The Electrochemical Impedance Spectroscopy (EIS) analysis exhibits the pure electronic behavior at hydrogen atmosphere. The maximum power density of ANZ-GDC composite anode based solid oxide fuel cell has been achieved 705 mW/cm(2) at 550 degrees C.

  • 43.
    Abbas, Maryam
    KTH, Skolan för industriell teknik och management (ITM), Industriell ekonomi och organisation (Inst.).
    Knowledge Management vid uppdragsarbete2011Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
  • 44.
    Abbas, Naeem
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Elektronik- och datorsystem, ECS.
    Runtime Parallelisation Switching for MPEG4 Encoder on MPSoC2008Självständigt arbete på avancerad nivå (masterexamen), 80 poäng / 120 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The recent development for multimedia applications on mobile terminals raised the need for flexible and scalable computing platforms that are capable of providing considerable (application specific) computational performance within a low cost and a low energy budget. The MPSoC with multi-disciplinary approach, resolving application mapping, platform architecture and runtime management issues, provides such multiple heterogeneous, flexible processing elements. In MPSoC, the run-time manager takes the design time exploration information as an input and selects an active Pareto point based on quality requirement and available platform resources, where a Pareto point corresponds to a particular parallelization possibility of target application. To use system’s scalability at best and enhance application’s flexibility a step further, the resource management and Pareto point selection decisions need to be adjustable at run-time. This thesis work experiments run-time Pareto point switching for MPEG-4 encoder. The work involves design time exploration and then embedding of two parallelization possibilities of MPEG-4 encoder into one single component and enabling run-time switching between parallelizations, to give run-time control over adjusting performance-cost criteria and allocation de-allocation of hardware resources at run-time. The newer system has the capability to encode each video frame with different parallelization. The obtained results offer a number of operating points on Pareto curve in between the previous ones at sequence encoding level. The run-time manager can improve application performance up to 50% or can save memory bandwidth up to 15%, according to quality request.

  • 45.
    Abbas Sohani, Amir
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Waste heat recovery from SSAB’s Steel plant in Oxelösund using a Heat Pump2016Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Detta projekt är inriktat på spillvärmepotentialer inom järn och stålindustrin. Högtemperaturvärme-pumpar för medelvarma temperaturkällor har modellerats. SSABs stålverk i Oxelusund har använts som exempel. Järn- och stålindustrin i Sverige är storkonsument av energi, tillsammans med pappers och massaindustrin. Det finns också en stor potential för spillvärmeåtervinning i stålindustrin. Det görs redan i Luleå t ex [1].

    Järn och stålindustrins produktionsmetoder och spillvärmeåtervinning, speciellt i USA och Sverige har studerats genom en litteraturstudie. Dagens metoder och potentialer för spillvärmeåtervinning inom järn och stålindustrin i Sverige studerades speciellt. SSABs anläggning i Oxelösund, har i decennier planerat inte bara att värma Oxelösunds stad som idag, utan också expandera till näraliggande Nyköping bara 12 km bort [2].

    Typiskt är den maximala framledningstemperaturen till Nyköpings fjärrvärmenät 110 °C den kallaste dagen. En spillvärme-värmepump når normalt inte upp till så höga temperaturer. Dock räcker 80 °C maximal framledningstemperatur från värmepumpen för att nyttiggöra spillvärmekällan kontinuerligt. Även en lägre temperatur som 75 °C skulle sannolikt räcka. Bara några få fjärrvärme-värmeväxlare i några hus skulle behöva bytas för att denna lägre temperatur skulle räcka till. De överskjutande graderna mellan 80 °C (75 °C) och 110 °C kan tas med värme från t ex existerande biobränslepannor lokalt i Nyköping.

    Att använda värmepumpar i detta sammanhang är inte självskrivet. Generellt är värmeflödena från ett stålverk så högtempererade att ingen värmpump behövs. Om man försöker komma åt dessa högtemperaturflöden i en gammal anläggning kan det bli väldigt dyrt och störa produktionen. Därför

    koncentrerades studien på medeltemperaturkällor (30 °C till 40 °C) och användande av högtemperaturvärmepumpar. Sådan värme dumpas nu med kyltorn. På så sätt kan 50 % av Nyköpings värmebehov tillgodoses med lätt tillgänglig spillvärme. Om man antar en värmefaktor på cirka 5, och lägger till värmepumpens förbrukade elektricitet blir det 62 % av Nyköpings fjärrvärmebehov.

    Oxelösundanläggningen är bara ett exempel och studien fokuseras på högtemperaturs-industriella värmepumpar HITIHP för sådana här och liknande användningar. Lämpliga komponenter och köldmedia har undersökts och generella konstruktionsprinciper av HITIHP föreslås. En litteraturstudie för att finna de bästa HITIHP-köldmedierna har gjorts.

    En tvåstegs högtemperaturvärmepump, som använder den tillgängliga värmekällans kapacitet och temperaturer tillsammans med fjärrvärmenätets krav, har modellerats och simulerats. Simuleringen har huvudsakligen gjorts med programmet EES. R245fa har t ex visat sig vara lämpligt som köldmedium i det andra steget av en högtemperaturvärmepump. Med R245fa kan till och med högre temperaturer än 90 °C uppnås till fjärrvärmesystemet. Tidigare skulle R134a ha använts i en sådan här applikation, men R245fa har t e lägre GWP (Global Warming Potential omkring 1000 istället för omkring 1300)[3]. Många olika köldmedia har simulerats i lågtemperatursteget av värmepumpen som initialt antogs vara en skruvkompressor-kaskad-värmepump. En större värmpump med två turbokompressorsteg och flashtank har också simulerats. Den gav också tillfredställande resultat. I det senare fallet studerades både R1234ZE(z) och R245fa som gav goda resultat men R1234ZE(z) ger mycket lägre GWP.

    Alla värmefaktorer (COP, energibehov, kondensortryck och tryckförhållanden (hög-/lågtryck) jämfördes. R245fa-R245fa och R600a-R245fa studerades noga i tvåstegs-kaskad-systemet med skruvkompressor. Dessa kombinationer gav bäst resultat. R717-R245fa var också bra men hade andra begränsningar. I tvåstegssystem med turbokompressorer och flashtank visade sig visade sig R1234ZE(z) ge gen bästa värmefaktorn. Man hade naturligtvis inte heller något temperaturfall i någon värmeväxlare mellan de två stegen. Om SSABs spillvärme av någon anledning inte skulle vara tillgängligt kan en sådan värmpump istället använda havsvatten som värmekälla.

    Begränsningen av koldioxidutsläppen är mycket svåra att beräkna. Detta kommer att bero mer på politisk övertygelse än på lättbevisade fakta. En mycket grov beräkning av kostnaden har också gjorts. Uppskattningsvis kommer projektet att kosta mellan 420 och 450 MSEK. Kostnadsuppskattningen inkluderar värmepumpen och en 12 km lång förbindelse till Nyköping. Kostnaden för värme levererad till Nyköping, kommer att variera mellan 0,2 kr/kWh och 0,65 kr/kWh när elpriset varieras mellan 0,5 och 2 SEK/kWh. Den högre värmkostnaden 0,65 kr/kWh beror också på att östersjövatten – inte spillvärme används som värmekälla.

    Värme från ett kyltorn kan återvinnas med en högtemperaturvärmepump. Den kan levereras från Oxelösund till Nyköping. De ekonomiska detaljerna har bar studerats översiktligt. Faktorer som om renovering den gamla pannan i Nyköping eller SSABs kyltorn kunde senareläggas, skulle kunna förbättra intresset för projektet. Ett spillvärmerör mellan Oxelösund och Nyköping har studerats sedan mitten av 70-talet av t ex Lars-Åke Cronholm [4]. Kan det vara dags nu?

  • 46.
    ABBAS, THOALFIQAR
    KTH, Skolan för industriell teknik och management (ITM), Tillämpad maskinteknik (KTH Södertälje).
    Utforma en monteringslina för solfångare2014Självständigt arbete på grundnivå (högskoleexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
  • 47.
    Abbas, Zainab
    KTH, Skolan för informations- och kommunikationsteknik (ICT).
    Streaming Graph Partitioning: Degree Project in Distributed Computing at KTH Information and Communication Technology2016Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Graph partitioning is considered to be a standard solution to process huge graphs efficiently when processing them on a single machine becomes inefficient due to its limited computation power and storage space. In graph partitioning, the whole graph is divided among different computing nodes that process the graph in parallel. During the early stages of research done on graph partitioning, different offline partitioning methods were introduced; these methods create high computation cost as they process the whole graph prior to partitioning. Therefore, an online graph partitioning method called as streaming graph partitioning was introduced later to reduce the computation cost by assigning the edges or vertices on-the-fly to the computing nodes without processing the graph before partitioning. In our thesis, we presented an experimental study of different streaming graph partitioning methods that use two partitioning techniques: vertex partitioning and edge partitioning. Edge partitioning has proved good for partitioning highly skewed graphs. After implementing different partitioning methods, we have proposed a partitioning algorithm that uses degree information of the vertices. Furthermore, we measured the effect of different partitioning methods on the graph stream processing algorithms. Our results show that for vertex partitioning Fennel has performed better than Linear Greedy as it shows lower edge-cuts and better load balancing. Moreover, for edge partitioning, the Degree based partitioner has performed better than Least Cost Incremental and Least Cost Incremental Advanced in reducing the replication factor, but the Degree based partitioner does not do well in load balancing. In the end, we show that the custom partitioning methods, compared to default hash partitioning, save the memory space by reducing the size of aggregate states during execution of different graph processing algorithms on the resulting partitions. The Degree based partitioner performed well by reducing the size of aggregate states on average up to 50%. Other algorithms include: Fennel, Linear Greedy, Least Cost Incremental and Least Cost Incremental Advanced, they reduced the size of aggregate states on average up to 21%, 10%, 27% and 48%.

  • 48. Abbasalizadeh, A.
    et al.
    Teng, Lidong
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Materialens processvetenskap.
    Seetharaman, Seshadri
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Materialens processvetenskap.
    Sietsma, J.
    Yang, Y.
    Rare Earth Extraction from NdFeB Magnets and Rare Earth Oxides Using Aluminum Chloride/Fluoride Molten Salts2015Ingår i: Rare Earths Industry: Technological, Economic, and Environmental Implications, Elsevier, 2015, 357-373 s.Kapitel i bok, del av antologi (Övrigt vetenskapligt)
    Abstract [en]

    In the current research, the feasibility of the recovery of neodymium and dysprosium from spent NdFeB magnets (about 6wt% Dy) was investigated using molten salt processes. The salt bath consisted of a eutectic composition of an NaCl-KCl-LiCl mixture. To enable the efficient dissolution of metal in the molten salt phase, AlCl3 was used as a chlorinating agent. Iron-free electrodeposition was carried out successfully. Energy-dispersive spectroscopic analysis of the electrodeposit revealed that co-deposition of the dysprosium occurs along with neodymium at the cathode. The process shows that this method is well suited for recovering rare earth metals from magnetic scrap containing these metals.Furthermore, the setup design for recovery of neodymium and dysprosium from their oxides was investigated with regard to previous studies on the neodymium magnets. The stability of different fluoride and chloride salts was studied by means of thermodynamic calculation. Aluminum fluoride-based molten salt systems were studied in detail as the electrolyte for electrochemical extraction of rare earth oxides into rare earth metal elements with Al.

  • 49. Abbasalizadeh, Aida
    et al.
    Malfliet, Annelies
    Seetharaman, Seshadri
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Sietsma, Jilt
    Yang, Yongxiang
    Electrochemical Extraction of Rare Earth Metals in Molten Fluorides: Conversion of Rare Earth Oxides into Rare Earth Fluorides Using Fluoride Additives2017Ingår i: JOURNAL OF SUSTAINABLE METALLURGY, ISSN 2199-3823, Vol. 3, nr 3, 627-637 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In the present research on rare earth extraction from rare earth oxides (REOs), conversion of rare earth oxides into rare earth fluorides with fluoride fluxes is investigated in order to overcome the problem of low solubility of the rare earth oxides in molten fluoride salts as well as the formation of oxyfluorides in the fluorination process. Based on thermodynamic calculations, a series of experiments were performed for converting the rare earth oxides into rare earth fluorides using AlF3, ZnF2, FeF3, and Na3AlF6 as fluorinating agents in a LiF-Nd2O3 system. The formation of neodymium fluoride as a result of the reactions between these fluxes and neodymium oxide is confirmed. The rare earth fluoride thus formed can subsequently be processed through the electrolysis route in the same reactor, and rare earth metal can be produced as the cathodic deposit. In this concept, the REO dissolution in molten fluorides would become unnecessary due to the complete conversion of the oxide into the fluoride, REF3. The results of XRD and EPMA analysis of the reacted samples indicate that AlF3, ZnF2, and FeF3 can act as strong fluorinating agents for the neodymium oxide giving rise to a complete conversion of neodymium oxide into neodymium fluoride.

  • 50. Abbasalizadeh, Aida
    et al.
    Malfliet, Annelies
    Seetharaman, Seshadri
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Sietsma, Jilt
    Yang, Yongxiang
    Electrochemical Recovery of Rare Earth Elements from Magnets: Conversion of Rare Earth Based Metals into Rare Earth Fluorides in Molten Salts2017Ingår i: Materials transactions, ISSN 1345-9678, E-ISSN 1347-5320, Vol. 58, nr 3, 400-405 s.Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In the present work, selective extraction of rare earth (RE) metals from NdFeB magnets is investigated by studying the effects of various fluxes, viz. AlF3, ZnF2, FeF3 and Na3AlF6 in the LiF-NdFeB system. The aim is to convert RE from RE magnet into the fluoride salt melt. The results show the complete selective separation of neodymium (also dysprosium) from the magnet and formation of rare earth fluoride, leaving iron and boron unreacted. The formed rare earth fluoride can subsequently be processed in the same reactor through an electrolysis route so that RE can be deposited as a cathode product. The results of XRD and EPMA analysis of the reacted samples indicate that AlF3, ZnF2 and FeF3 can act as strong fluorinating agents for extraction of rare earth from NdFeB magnet, converting the RE to REF3. The results confirm the feasibility of the rare earth metals recovery from scrap NdFeB magnet as raw material. The fluoride conversion- electrolysis route suggested in the present work enables the extraction of rare earth metals in a single step using the above-mentioned fluxes.

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