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  • 122851.
    Westin, Elin M.
    et al.
    Outokumpu Stainless AB, Avesta Research Centre.
    Keehan, Enda
    Esab AB.
    Ström, Mats
    Nordic Laser Production AB.
    Von Brömssen, Bernt
    Nordic Laser Production AB.
    Laser welding of a lean duplex stainless steel2007Ingår i: 26th International Congress on Applications of Lasers and Electro-Optics, ICALEO 2007: Congress Proceedings, 2007, s. 335-344Konferensbidrag (Refereegranskat)
    Abstract [en]

    Nd:YAG laser welding and laser gas tungsten arc (GTA) hybrid welding of the lean duplex stainless steel LDX 2101® (EN 1.4162, UNS S32101) were performed with and without filler wire and nitrogen additions to the shielding gas. The high energy density associated with laser welding of duplex stainless steels can affect the mechanical strength and corrosion resistance negatively. The high solidification rates and cooling rates characteristic of laser welding may cause ferritization and chromium nitride precipitation. However, due to the balanced composition of LDX 2101, the austenite reformation in the weld metal and the heat affected zone (HAZ) was satisfactory as confirmed by tensile test results, corrosion performance in terms of critical pitting temperature (CPT) and hardness measurements. Transmission electron microscopy (TEM) was conducted on simulated HAZs to study the effect of cooling rate on precipitate formation. Furthermore, Laser-GTA hybrid welding of the galvanized carbon steel Dogal® DP 600 onto LDX 2101 in lap joints was successful without porosity or liquid metal embrittlement (LME), and with sufficient tensile strength.

  • 122852.
    Westin, Elin M.
    et al.
    Outokumpu Stainless, Avesta Research Centre.
    Olsson, Claes-Olof Anders
    Outokumpu Stainless, Avesta Research Centre.
    Hertzman, Staffan
    Outokumpu Stainless Research Foundation.
    Weld oxide formation on lean duplex stainless steel2008Ingår i: Corrosion Science, ISSN 0010-938X, E-ISSN 1879-0496, Vol. 50, nr 9, s. 2620-2634Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Weld oxides have a strong influence on corrosion resistance, but have hitherto only been studied to a limited extent for duplex stainless steels. X-ray photoelectron spectroscopy (XPS) has here been used to study heat tint formed on gas tungsten arc (GTA) welds on the commercial duplex grades LDX 2101 (EN 1.4162/UNS S32101) and 2304 (EN 1.4362/UNS S32304) welded with and without nitrogen additions to the shielding gas. The process of heat tint formation is discussed in terms of transport phenomena to explain the effect of atmosphere, temperature and composition. The oxides formed were found to be enriched in manganese and corrosion testing shows that nitrogen has a strong influence on the weld oxide. A mechanism is proposed including evaporation from the weld pool and subsequent redeposition.

  • 122853.
    Westin, Emil
    KTH, Skolan för datavetenskap och kommunikation (CSC).
    Visualization of Quantified Self with movement and transport data2017Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Transportsystem står för en stor del av världens koldioxidutsläpp. För att nå utsatta utsläppsmål måste färre resor göras med bil och användandet av hållbara transportmedel öka hos individer. Genom att börja spåra sig själv inom olika områden, och genom att bli presenterad sin insamlade data, kan individer upptäcka och lära sig om vanor, mönster och praxis bland dem själva. I denna avhandling undersöks hur mycket individer vet om sina egna koldioxidutsläpp som skapas av de transportmedel som de använder dagligen.

    I studien undersöks hur en visualisering av personlig rörelse- och transportdata påverkar individens förståelse av sitt eget koldioxidavtryck samt dennes motivation till att använda mer hållbara transportmedel. En användarstudie genomfördes med 15 deltagare över två veckor. Under denna period fick deltagarna spåra sina förflyttningar och vilka transportmedel som användes med hjälp av en applikation på en smart telefon. Det insamlade transportdata presenterades därefter i en webb- applikation med avseende på deltagarnas koldioxidutsläpp. Innan och efter användarstudien fick deltagarna svara på ett självutvärderingsformulär baserat på beteendemodellen COM-B.

    Resultaten visade att deltagarnas förståelse ökade när det gäller att sätta sina utsläppsmängder i förhållande till vad som är lågt respektive högt mellan olika transportmedel. En ökad medvetenhet om personliga transportmönster och hur stor miljöpåverkan valet av transportläge har, indikerades. Vidare verkar deltagarnas motivation att använda mer hållbara transportmedel vara beroende utav om de inser att de har låga eller höga utsläpp, men också om det finns tillgängliga, alternativa, transportmedel att byta till. 

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  • 122854.
    Westin, Emil
    et al.
    KTH, Skolan för datavetenskap och kommunikation (CSC).
    Whittaker, Kevin
    KTH, Skolan för datavetenskap och kommunikation (CSC).
    Får jag störa en sekund?: En studie om mobilnotifikationers påverkan på upplevd stress och fokus2015Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Mobilnotifikationer är ett relativt nytt fenomen och mobilanvändare idag får allt fler notifikationer skickade till sig per dag. Hur de faktiskt påverkar användare, både sett till mobilanvändning och användarbeteenden, är fortfarande ett tämligen outforskat område. Denna studie utforskar hur mobilnotifikationer påverkar studenters upplevda stressnivåer och fokus under schemalagda skolaktiviteter. För att undersöka detta jämfördes en normal vecka med en vecka då notifikationer tystades med hjälp av stör-ej-funktionen i mobiltelefonen. Under denna period loggades mobilanvändningen och deltagarna fick föra en dagbok för reflektioner kring sitt beteende under dagen. Undersökningen avslutades med semi-strukturerade intervjuer.

    Resultaten av undersökningen visade att mobilanvändningen höll en jämn nivå under hela undersökningen. Ingen stress upplevdes av deltagarna i samband med mottagna notifikationer i skolmiljön, däremot upplevdes bättre fokus då stör-ej-funktionen aktiverades och notifikationerna tystades. Ett samband mellan få antal mottagna notifikationer och bättre upplevt fokus upptäcktes. 

    Undersökningen har även haft ett metodologiskt syfte då fler undersökningar krävs i detta område. En slutsats vi drar efter avslutad studie är att tillvägagångsättet lämpar sig bra för att jämföra upplevd med faktisk mobilanvändning. Kombinationen dagbok och semi-strukturerade intervjuer var även ett bra tillvägagångssätt för att fånga upp deltagarnas beteenden och reflektioner.

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  • 122855.
    Westin, Fredrik
    KTH, Tidigare Institutioner                               , Maskinkonstruktion.
    Accuracy of turbocharged SI-engine simulations2002Licentiatavhandling, monografi (Övrigt vetenskapligt)
    Abstract [en]

    This licentiate thesis deals mainly with modelling ofturbocharged SIengines. A model of a 4-cylinder engine was runin both steady state and transient conditions and the resultswere compared to measured data. Large differences betweenmeasurements and simulations were detected and the reasons forthis discrepancy were investigated. The investigation showedthat it was the turbocharger turbine model that performed in anon-optimal way. To cope with this, the turbine model containedparameters, which could be adjusted so that the model resultsmatched measured data. However, it was absolutely necessary tohave measured data to match against. It was thus concluded thatthe predictivity of the software tool was too poor to try topredict the performance of various boosting systems. Thereforemeans of improving the modelling procedure were investigated.To enable such an investigation a technique was developed tomeasure the instantaneous power output from, and efficiency of,the turbine when the turbocharger was used on the engine.

    The project’s initial aim was to predict, throughsimulations, the best way to boost a downsized SI-engine with avery high boost-pressure demand. The first simulation run on astandard turbocharged engine showed that this could not be donewith any high accuracy. However, a literature study was madethat presents various different boosting techniques that canproduce higher boost pressure in a larger flow-range than asingle turbocharger, and in addition, with smallerboost-pressure lag.

    Key words:boosting, turbocharging, supercharging,modelling, simulation, turbine, pulsating flow, unsteadyperformance, SI-engine, measurement accuracy

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  • 122856.
    Westin, Fredrik
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Simulation of turbocharged SI-engines - with focus on the turbine2005Doktorsavhandling, monografi (Övrigt vetenskapligt)
    Abstract [en]

    The aim is to share experience gained when simulating (and doing measurements on) the turbocharged SI-engine as well as describing the limits of current state of the technology. In addition an overview of current boosting systems is provided.

    The target readers of this text are engineers employed in the engine industry as well as academia who will get in contact, or is experienced, with 1D engine performance simulation and/or boosting systems. Therefore the text requires general knowledge about engines.

    The papers included in the thesis are, in reverse chronological order:

    [8] SAE 2005-XX-XXX Calculation accuracy of pulsating flow through the turbine of SI-engine turbochargers - Part 2 Measurements, simulation correlations and conclusions Westin & Ångström

    To be submitted to the 2005 SAE Powertrain and Fluid Systems Conference in San Antonio

    [7] SAE 2005-01-2113 Optimization of Turbocharged Engines’ Transient Response with Application on a Formula SAE / Student engine Westin & Ångström

    Approved for publication at the 2005 SAE Spring Fuels and Lubricants Meeting in Rio de Janeiro

    [6] SAE 2005-01-0222 Calculation accuracy of pulsating flow through the turbine of SI-engine turbochargers - Part 1 Calculations for choice of turbines with different flow characteristics Westin & Ångström

    Published at the 2005 SAE World Congress in Detroit April 11-14, 2005

    [5] SAE 2004-01-0996 Heat Losses from the Turbine of a Turbocharged SI-Engine – Measurements and Simulation Westin, Rosenqvist & Ångström

    Presented at the 2004 SAE World Congress in Detroit March 8-11, 2004

    [4] SAE 2003-01-3124 Simulation of a turbocharged SI-engine with two software and comparison with measured data Westin & Ångström

    Presented at the 2003 SAE Powertrain and Fluid Systems Conference in Pittsburgh

    [3] SIA C06 Correlation between engine simulations and measured data - experiences gained with 1D-simulations of turbocharged SI-engines Westin, Elmqvist & Ångström

    Presented at the SIA International Congress SIMULATION, as essential tool for risk management in industrial product development in Poissy, Paris September 17-18 2003

    [2] IMechE C602/029/2002 A method of investigating the on-engine turbine efficiency combining experiments and modelling Westin & Ångström

    Presented at the 7th International Conference on Turbochargers and Turbocharging in London 14-15 May, 2002

    [1] SAE 2000-01-2840 The Influence of Residual Gases on Knock in Turbocharged SI-Engines Westin, Grandin & Ångström

    Presented at the SAE International Fall Fuels and Lubricants Meeting in Baltimore October 16-19, 2000

    The first step in the investigation about the simulation accuracy was to model the engine as accurately as possible and to correlate it against as accurate measurements as possible. That work is covered in the chapters 3 and 5 and in paper no. 3 in the list above. The scientific contribution here is to isolate the main inaccuracy to the simulation of turbine efficiency.

    In order to have anything to compare the simulated turbine efficiency against, a method was developed that enables calculation of the CA-resolved on-engine turbine efficiency from measured data, with a little support from a few simulated properties. That work was published in papers 2 and 8 and is the main scope of chapter 6 in the thesis. The scientific contributions here are several:

    · The application on a running SI-engine is a first

    · It was proven that CA-resolution is absolutely necessary in order to have a physically and mathematically valid expression for the turbine efficiency. A new definition of the time-varying efficiency is developed.

    · It tests an approach to cover possible mass accumulation in the turbine housing

    · It reveals that the common method for incorporating bearing losses, a constant mechanical efficiency, is too crude.

    The next step was to investigate if different commercial codes differ in the results, even though they use equal theoretical foundation. That work is presented in chapter 4, which corresponds to paper 4. This work has given useful input to the industry in the process of choosing simulation tools.

    The next theory to test was if heat losses were a major reason for the simulation accuracy. The scientific contribution in this part of the work was a model for the heat transport within the turbocharger that was developed, calibrated and incorporated in the simulations. It was concluded that heat losses only contributed to a minor part of the inaccuracy, but that is was a major reason for a common simulation error of the turbine outlet temperature, which is very important when trying to simulate catalyst light off. This work was published in paper 5 and is covered in chapter 7.

    Chapter 8, and papers 6 and 8, covers the last investigation of this work. It is a broad study where the impact of design changes of both manifold at turbines on both simulation accuracy as well as engine performance. The scientific contribution here is that the common theory that the simulation inaccuracy is proportional to the pulsation amplitude of the flow is non-valid. It was shown that the reaction was of minor importance for the efficiency of the turbine in the pulsating engine environment. Furthermore it presents a method to calculate internal flow properties in the turbine, by use of a steady-flow design software in a quasi-steady procedure. Of more direct use for the industry is important information of how to design the manifolds as well as it sheds more light on how the turbine works under unsteady flow, for instance that the throat area is the single most important property of the turbine and that the system has a far larger sensitivity to this parameter than to any other design parameters of the turbine. Furthermore it was proven that the variation among individual turbines is of minor importance, and that the simulation error was of similar magnitude for different turbine manufacturers.

    Paper 7, and chapter 9, cover a simulation exercise where the transient performance of turbocharged engines is optimised with help from factorials. It sorts out the relative importance of several design parameters of turbocharged engines and gives the industry important information of where to put the majority of the work in order to maximize the efficiency in the optimisation process.

    Overall, the work presented in this thesis has established a method for calibration of models to measured data in a sequence that makes the process efficient and accurate. It has been shown that use of controllers in this process can save time and effort tenfold or more.

    When designing turbocharged engines the residual gas is a very important factor. It affects both knock sensitivity and the volumetric efficiency. The flow in the cylinder is in its nature of more dimensions than one and is therefore not physically modelled in 1D codes. It is modelled through models of perfect mixing or perfect displacement, or at a certain mix between them. Before the actual project started, the amount of residual gases in an engine was measured and it’s influence on knock was established and quantified. This was the scope of paper 1. This information has been useful when interpreting the model results throughout the entire work.

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  • 122857. Westin, Fredrik
    et al.
    Elmqvist, Christel
    Ångström, Hans-Erik
    Correlation between engine simulations and measured data: experiences gained with 1D-simulations of turbocharged SI-enginesManuskript (Övrigt vetenskapligt)
  • 122858.
    Westin, Fredrik
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Ångström, Hans-Erik
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Calculation accuracy of pulsating flow through the turbine of si-engine turbochargers: Part 1 calculations for choice of turbines with different flow characteristics2005Konferensbidrag (Refereegranskat)
    Abstract [en]

    The paper treats pulsating flow through the turbine of SI-engine turbochargers. In engine design, 1D engine-simulations are very convenient tools for optimization and concept studies. However, they have drawbacks in certain areas. The accuracy, when predicting turbocharger turbine power, is lower than desired. The reason for that is a lack of knowledge about the phenomenon of pulsating flow through the turbine. The background to the problem is described in the paper. This investigation aims at learning more about this unsteady, pulsating flow, on the engine. The method used is to do large parameter changes to several parameters in turbine and manifold designs such as A/R and trim in the turbine and also volume and length of the exhaust manifold. For selection of A/R and trim, as well as an aid in the analysis of measured data, the meanline turbine design software Rital from Concepts NREC [1] was used. Three different turbines were investigated, all with the same mass flow capacity. The three different manifolds were designed to alter the pulsation shape at the turbine inlet. The calculation results show, that through these large parameter changes, it is possible to significantly alter the conditions at both the turbine inlet (shape of pressure and massflow curves) and at the turbine wheel inlet (flow angle and velocity). This has a significant impact on the performance of the turbine and engine.

  • 122859.
    Westin, Fredrik
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Ångström, Hans-Erik
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Calculation accuracy of pulsating flow through the turbine of SI-engine turbochargers: Part 2 measurements, simulation correlations and conclusions2005Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper is a continuation of SAE-Paper 2005-01-0222 presented at the 2005 SAE World Congress, denoted Part 1 in this text. In Part 1 three turbines were selected from calculations and three manifolds with different geometries were designed. This paper, Part 2, covers the results from engine-simulations and measurements on these nine different combinations of turbines and manifolds. It was shown that the possibility of maintaining isentropic power was the most important property, overshadowing any differences in turbine efficiency. The isentropic power was inversely dependent on both manifold volume and turbine throat area. The GT-Power models of all nine setups were calibrated against the measured data. The need for efficiency and massflow multipliers is described. The efficiency multiplier depended on mass flow through the turbine, with a distinct minimum value (0.7-0.8) around 0.03 kg/s and higher around that. The efficiency multiplier could not be shown to depend on pulsation amplitude of the turbine inlet flow. The mass flow multiplier was almost linear with engine speed. The on-engine turbine efficiency was calculated from a combination of measured and simulated data. Different approaches for this calculation were tested, among which also mass storage was included. The chosen method used equal massflow in and out from the turbine at every instant and a floating average over 30 CAD. To enable explanation of the different behaviors on the engine, detailed measurements were conducted on the three turbines in a steady-state turbine flow rig. These measurements were used to calibrate separate turbine simulation models in the software Rital, which were used to describe the internal flow of the turbines. The three methods of estimating the on-engine turbine efficiency were compared. GT-Power and Rital showed similar trends for the efficiency, but the on-engine measured efficiency gave lower values for the first, most energetic, part of the exhaust pulse. Furthermore, the three manifold types were analyzed and the benefits from each of them sorted out.

  • 122860.
    Westin, Fredrik
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Ångström, Hans-Erik
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Maskinkonstruktion (Avd.).
    Optimization of turbocharged engines' transient response with application on a formula SAE / Student engine2005Ingår i: SAE Technical Papers, ISSN 0148-7191Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this study, the transient response of a turbocharged engine is minimized by using 1D engine simulation. A method is developed where sequential fractional factorial designs are utilized to first determine the relative importance between a wide range of design parameters and then successively come closer to an optimal setup for minimized transient response. This methodology is first developed and applied to a 2-liter standard production car engine and then it is used for optimization of the 2004 KTH Racing Formula Student engine. The race engine was first designed entirely by using steady-state 1D simulations. These simulations are described and the design explained. The philosophy behind turbocharger selection, manifold tuning etc. is described in detail. After the initial design the engine was optimized for transient response. Measurement data from steady state measurements on the dynamometer is showed for verification as well as pressure data logged in the car on the racetrack.

  • 122861.
    Westin, Fredrik
    et al.
    KTH, Tidigare Institutioner, Maskinkonstruktion.
    Ångström, Hans-Erik
    KTH, Tidigare Institutioner, Maskinkonstruktion.
    Rosenqvist, J.
    Heat losses from the turbine of a turbocharged SI-engine - Measurements and simulation2004Konferensbidrag (Refereegranskat)
    Abstract [en]

    Traditionally, heat losses from the turbine are neglected in turbomatching calculations as well as in engine simulations [1]. On the SI-engine, with it's high exhaust temperatures, this assumption will lead to errors in the calculations. Significant amounts of heat are dissipated from the turbine through several mechanisms. This paper contains measurements of the different heat loss mechanisms from the turbine during full load operation on a 4-cylinder SI-engine. The largest loss components are convective and radiative. The heat losses to cooling water and lubrication oil were approximately 3-5% of the total heat loss from the turbine. In addition to heat losses to the surroundings, heat flux is also present internally in the turbocharger. Heat flux from the turbine to the compressor can deteriorate the efficiency of the compressor. Measurements and calculations were performed for several heat flux conditions and it could be concluded that little possibility exists for significant heat flux through the rotor, instead the major heat flux comes from conduction in the housings and external radiation. With the heat transfer included in the model the turbine outlet temperature could be simulated very close to measured. However, incorporation of the heat losses in the simulation did not do very much for the necessity of using correction factors for the turbine efficiency.

  • 122862.
    WESTIN, ISAK
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.).
    Sensorlos reglering av en PMSM2016Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Det har examensarbetet ar gjort tillsammans med KTH och Husqvarna AB. Husqvarna ar en av varldens framsta tillverkare av utomhusprodukter. En motorsag som ar utvecklad av Husqvarna, som drivs av en permanent magnet synchronous motor (PMSM), regleras for tillfallet med en sensorlos brushless DC-baserad regleringsstrategi. For att oka motorns e ektivitet, och for att fa en mer exibel stromreglering, sa vill Husqvarna utforska mojligheten att anvanda en sensorlos PMSM-baserad regleringsstrategi istallet som kallas eld-oriented control (FOC). En reglering klassas som sensorlos nar informationen om motoraxelns position och hastighet som anvands i regleringen ges av en estimator istallet for en sensor. Malet med det har examensarbetet ar alltsa att utvardera olika hastighets- och positionsestimatorer som gar att tillampa i en FOC.

    Arbetet kommer att innefatta en fallstudie som bestar av en PMSM som ar lamplig for att driva en batteridriven motorsag. Arbetet ar sedan uppdelat i tva steg. Forsta steget ar att gora en litteraturstudie for att fa en overblick over olika hastighets- och positionsestimatorer och for att fa tillrackligt med kunskap for att kunna avgora vilka metoder som kommer fungera i den har fallstudien. De olika metoderna jamfors i forhallande till nagra forbestamda aspekter som ska representera onskade egenskaper hos en estimator. Nasta steg ar att modellera och simulera de en eller tva metoderna som verkade mest lampliga enligt litteraturstudien. I simuleringarna sa reglerar varje metod motorn nar den kor igenom ett antal testfall. Testfallen ar konstruerade att avbilda riktiga anvandningsscenarion for motorn som skulle kunna intra a vid anvandande av slutprodukten. De olika metoderna modelleras i bade kontinuerlig form, for att se att de fungerar, och diskret form for att komma narmare verkligheten. De kombinerade resultaten fran simulationerna och litteraturstudien ar tankta att indikera vilken metod som skulle passa bast i en sensorlos regleringsstrategi for motorn i den har fallstudien.

    Baserat pa litteraturstudien sa valdes model reference adaptive system (MRAS) och sliding mode observer (SMO) till att bli modellerade och simulerade. Simuleringarna for bada metoderna visar bra resultat i kontinuerlig form. Men nar SMO simuleras i diskret form sa blir den valdigt brusig och gor sa att hela reglersystem blir instabilt. MRAS visar a andra sidan lika bra resultat i diskret form som i kontinuerlig. MRAS visar ocksa en overlag battre estimeringsprestanda, bade for olika lastfall och for parametervariationer i motorn. Eftersom MRAS aven lampar sig for resistansuppskattning, vilket ar en anvandbar funktion, sa kommer den att bli foreslagen som det battre valet i det sensorlosa reglersystemet for fallstudien.

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  • 122863.
    Westin, Johan
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg.
    Ballistic Impact Properties of Fibre-Reinforced Composite Structures 2011Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

      

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  • 122864.
    Westin, Jonas
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap, Transport- och lokaliseringsanalys.
    Efficiency and acceptability of pricing policies and transport investments in distorted economies2012Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    This thesis contains five papers studying the economic efficiency and political acceptability of road pricing policies and transport investments in distorted economies. Interactions between the transport market and other distorted markets, such as the labor market, can have a large impact on the welfare effect of a road pricing policy or a transport investment. Many road pricing studies therefore try to incorporate effects from other distorted markets in the analysis. Paper I analyzes how the economic efficiency of a road toll in a distorted economy depends on assumptions about the initial tax system. In the road pricing literature, the welfare effect of a road toll is often found to depend on revenue use. Using a simple general equilibrium model paper I shows that the relative efficiency of marginal revenue recycling policies depends more on assumptions regarding inefficiencies in the initial tax system than on the road toll per se. Paper II studies the effect on welfare, equity and labor supply from a road toll in a commuting population with heterogeneous value of time and endogenous labor supply. When explicitly taking into account that commuters have different value of time, the road toll can increase total labor supply even when the revenues are not recycled back to the commuters. The analysis stresses the importance of recognizing traveler heterogeneity when analyzing congestion pricing. Road pricing policies are often characterized by conflicting interests between different stakeholders and different geographical areas. Papers III and IV study the economic efficiency and political acceptability of pricing and investment policies in different institutional and geographical settings. The main contribution of the papers is to explain how political constraints can lead to inefficient tolling strategies. The papers contribute to the existing literature on political acceptability of road pricing by analyzing the conflict and potential trade-off between political acceptability and economic efficiency. A difficulty when assessing the welfare effect of a future transport policy is also that many factors and parameters needed for the analysis are uncertain. Paper V studies the climate benefit of an investment in high speed rail by calculating the magnitude of annual traffic emission reduction required to compensate for the annualized embedded emissions from the construction of the line. The paper finds that to be able to balance the annualized emissions from the construction, traffic volumes of more than 10 million annual one-way trips are usually required, and most of the traffic diverted from other transport modes must come from aviation.

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    Westin_2012
  • 122865.
    Westin, Jonas
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap, Transport- och lokaliseringsanalys.
    Evaluating road tolls in the presence of tax distortions: Revenue recycling revisitedManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    A well-known result in the road pricing literature is that the welfare potential of a road toll critically depends on revenue use. Using a simple general equilibrium model we show that the relative efficiency of different revenue recycling policies depends more on assumptions regarding inefficiencies in the initial tax system than on the road toll per se. Without a thorough analysis of the initial tax systemand the political situation surrounding the decision, it might make more sense to analyze the effect of road pricing “as if” the policy instruments in the no-toll situation are chosen on welfare maximizing principles.

  • 122866.
    Westin, Jonas
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap, Transport- och lokaliseringsanalys.
    Labor Market Effects of Congestion Pricing in a Heterogeneous PopulationManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Do congestion pricing reduce labor supply? Since a congestion charge raises the monetary cost of car commuting, concerns have been raised that the toll may decrease labor supply at the extensive margin in a similar way as an income tax. The paper studies the effect of a congestion charge on welfare, equity and labor supply in a commuting population with heterogeneous value of time and endogenous labor supply. The congestion charge decreases labor supply among commuters who change from car to public transport, but increases labor supply among the remaining car commuters. When explicitly taking into account that commuters have different value of time, aggregate labor supply is found to increase even when the revenues are not recycled back to the commuters. This indicates that a congestion charge by itself does not reduce aggregate labor supply. The analysis hence stresses the importance of recognizing traveler heterogeneity when analyzing congestion pricing.

  • 122867.
    Westin, Jonas
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transporter och samhällsekonomi (stängd 20110301), Transport och lokaliseringsanalys (stängd 20110301). KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Centra, Centrum för transportstudier, CTS.
    Labor Market Effects of Road Pricing in a Population with Continuously Distributed Value of Time2010Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    The purpose of the presentation is to analyze the labor market effects of a congestion charge when commuters have continuously distributed value of time. Since a congestion charge raises the cost of commuting to work, it can decrease employment at the extensive margin in a similar way as an income tax. Without any form of revenue recycling, the resulting welfare loss from the decreased employment can even exceed the Pigouvian welfare gain from internalizing the congestion externality. A common conclusion in the literature, when comparing different revenue recycling schemes, is that it in general is more effective to use the revenues to cut taxes in the labor market compared to subsidizing public transport or returning them in a lump-sum transfer. A critical assumption in many of the previous cost-benefit analyses of congestion charges is however that there only exists a single value of time. This is somewhat surprising since one of the main features of a congestion charge is that it sorts people according to their value of time, given the existence of feasible transport alternatives. This paper intends to challenge this conclusion by analyzing how previous results hold if we, instead of using a representative individual, consider a population with a continuously distributed value of time. The model used in the paper is created with the Stockholm congestion charging trial in mind, but the analysis can just as well be applied to any city with a well developed public transport service. In the paper a simple traffic model is embedded within a general equilibrium framework where a large number of individuals with different values of time choose labor supply at the extensive margin and mode of transportation. In contrast to previous models, a modal-choice approach is used to model how the value of time for different individuals affects their choice of travel mode. The disaggregated travel demand model makes it possible to analyze how self-selection of mode choice affects labor supply, total welfare and the relative performance of the different revenue recycling schemes. Special attention will also be given to the distributional impacts of the different recycling schemes.

  • 122868.
    Westin, Jonas
    KTH, Tidigare Institutioner                               , Mekanik.
    Laninar-turbulent boundary layer transition influenced by free stream turbulence1997Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Laminar-turbulent transition in a flat plate boundary layerhas been considered, with a special emphasis on the influencefrom free stream turbulence (FST)

    First, experiments on linear stability ofTollmien-Schlichting (TS) waves in a Blasius boundary layer wasstudied. This is a well-known example from hydrodynamicstability theory, which has hitherto suffered from unresolveddiscrepancies between experiments and linear theory. Thepresent results showed good agreement with the theory, and itwas also shown that inappropriate leading edge conditions mayhave affected earlier experimental studies.

    In a series of experiments the interest has been focussed ontransition at moderate levels of free stream turbulence. Theresponse of a laminar boundary layer subjected to a free streamturbulence level of 1.5% formed the basis for the study, andthe general characteristics of FST-induced disturbances weredetermined. It was shown that the FST gives rise tonon-stationary streaky structures inside the laminar boundarylayer, which result in streamwise fluctuations with rms-valuesof the order of 10% before transition starts. Moreover, it wasshown that the introduction of TS-waves together with the largeamplitude streaks could lead to a considerable enhancement ofthe transition process.

    Since the random character of FST-induced boundary layerdisturbances can effectively obscure important details in theflow, a model experiment simulating the process through whichfree stream eddies transform into streaky structures inside theboundary layer was studied. This was done by means of alocalized free stream disturbance introduced upstream of theleading edge. The importance of streamwise vorticity in thereceptivity process was clearly indicated. It was also shownthat localized streaky structures, which decayed in amplitudeduring the downstream development, could exhibit a strongamplification if a TS-wave was generated simultaneously. It issuggested that similar non-linear interactions may occur in aboundary layer subjected to moderate levels of free streamturbulence.

    Besides the experimental work, a study related to transitionprediction at high levels of free stream turbulence is includedin the thesis. The possibility to use differential ReynoldsStress Transport Models for transition prediction isconsidered, and some aspects concerning the sensitivity to freestream boundary conditions are discussed.

    Keywords:Laminar-turbulent transition, hot-wiremeasurements, Tollmien-Schlichting waves, free streamturbulence, receptivity, localized disturbances, nonlinearinteraction, transition modelling

  • 122869.
    Westin, Jonas
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Centra, Centrum för transportstudier, CTS. KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap, Transport- och lokaliseringsanalys.
    Olika aspekter av arbetsmarknadseffekter för trängselskatt2012Konferensbidrag (Övrig (populärvetenskap, debatt, mm))
  • 122870.
    Westin, Jonas
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap, Transport- och lokaliseringsanalys. KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Centra, Centrum för transportstudier, CTS.
    Räkneövning banavgifter2011Rapport (Övrigt vetenskapligt)
  • 122871.
    Westin, Jonas
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap, Transport- och lokaliseringsanalys. KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Centra, Centrum för transportstudier, CTS.
    The Climate Effect of High Speed Rail2011Konferensbidrag (Övrig (populärvetenskap, debatt, mm))
  • 122872.
    Westin, Jonas
    Umeå universitet.
    Trängselavgifter utan trängsel – när är det en bra idé?2013Konferensbidrag (Refereegranskat)
  • 122873.
    Westin, Jonas
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Centra, Centrum för transportstudier, CTS. KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap, Transport- och lokaliseringsanalys.
    Välfärdseffekter av trängselavgifter2011Konferensbidrag (Refereegranskat)
  • 122874.
    Westin, Jonas
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transporter och samhällsekonomi (stängd 20110301), Transport och lokaliseringsanalys (stängd 20110301). KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Centra, Centrum för transportstudier, CTS.
    Welfare Effects of Road Pricing in a Population with Continuously Distributed Value of Time2010Rapport (Övrigt vetenskapligt)
  • 122875.
    Westin, Jonas
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap, Transport- och lokaliseringsanalys.
    Welfare Effects of Transport Policies: an analysis of congestion pricing and infrastructure investments2011Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Interactions between the transport market and other distorted markets, such as the labor market, can have a large impact on the overall welfare effect of a road pricing policy or a congestion charge. Many road pricing studies therefore try to incorporate effects from other distorted markets in the analysis. A difficulty when assessing the welfare effect of a future transport policy is also that many factors and parameters needed for the analysis is uncertain.

    This thesis contains three papers all studying different methodological approaches to analyzing the welfare effects of transport policies. The first two papers analyze the welfare effect of congestion pricing in distorted economies. The main contribution of the first paper is to analyze how the welfare effect of a congestion charge in a distorted economy depends on what assumptions we make regarding the tax system in the initial no-toll situation. A critical assumption in many cost-benefit analyses of congestion charges is that the whole population has a single value of time. The second paper studies the effect of a congestion charge in a population of commuters with a continuously distributed value of time. The main contribution of the paper, compared to previous literature, is that it studies the welfare effect and distributional impact of a congestion charge in a population with endogenous labor supply and heterogeneous value of time where mode-choice self-selection plays an important role.

    The third paper studies the climate benefit of an investment in high speed rail by calculating the magnitude of annual traffic emission reduction required to compensate for the annualized embedded emissions from the construction of the line. To account for uncertainties in underlying assumptions, a Monte Carlo simulation framework is used in the analysis. The paper finds that to be able to balance the annualized emissions from the construction, traffic volumes of more than 10 million annual one-way trips are usually required, and most of the traffic diverted from other transport modes must come from aviation.

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    FULLTEXT01
  • 122876.
    Westin, Jonas
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Centra, Centrum för transportstudier, CTS. KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap, Transport- och lokaliseringsanalys.
    Basck, Pierre
    LET, Université de Lyon.
    Franklin, Joel
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Centra, Centrum för transportstudier, CTS. KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap, Transport- och lokaliseringsanalys.
    Proost, Stef
    CES, KU Leuven.
    Raux, Charles
    LET, Université de Lyon.
    Achieving political acceptability for new transport infrastructure in congested urban regions2012Rapport (Övrigt vetenskapligt)
    Abstract [en]

    The paper analyzes the political acceptability of policies targeted at relieving urban congestion. The paper combines a stylized model of an urban transport network with a somewhat more detailed model of the political process that incorporates interactions between voters, special interest groups and politicians to explore the possibilities to reach political acceptability for efficient transport policies. In a case study of a proposed bypass in Lyon, France, the paper compares a set of potential policies in terms of efficiency, equity and political acceptability. A possible explanation for the difficulty of achieving political support for efficient transport policies is that since urban road pricing policies are characterized by conflicting interest, the political decision making process must balance different interests against each other to reach an efficient outcome. The analysis suggest that the difficulty to achieve political support for efficient road pricing policies is not a lack of political acceptability; instead the difficulty arises because of low political feasibility for efficient transport pricing since non-efficient transport policies are seen as more attractive to the decision makers.

  • 122877.
    Westin, Jonas
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Centra, Centrum för transportstudier, CTS. KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap, Transport- och lokaliseringsanalys.
    Basck, Pierre
    Laboratoire d’Economie des Transports.
    Franklin, Joel
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Centra, Centrum för transportstudier, CTS. KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap, Transport- och lokaliseringsanalys.
    Proost, Stef
    Katholieke Universiteit Leuven.
    Raux, Charles
    Laboratoire d’Economie des Transports.
    Achieving political acceptability for new transport infrastructure in congested urban regions2012Konferensbidrag (Refereegranskat)
  • 122878.
    Westin, Jonas
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap, Transport- och lokaliseringsanalys. KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Centra, Centrum för transportstudier, CTS.
    Franklin, Joel
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap, Transport- och lokaliseringsanalys. KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Centra, Centrum för transportstudier, CTS.
    Grahn-Voorneveld, Sofia
    Acceptability and Political Coordination of Road User Charges2011Konferensbidrag (Övrigt vetenskapligt)
  • 122879.
    Westin, Jonas
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Centra, Centrum för transportstudier, CTS. KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap, Transport- och lokaliseringsanalys.
    Franklin, Joel
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Centra, Centrum för transportstudier, CTS. KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap, Transport- och lokaliseringsanalys.
    Grahn-Voorneveld, Sofia
    VTI.
    Proost, Stef
    Acceptability and Political Coordination of Road User Charges2012Konferensbidrag (Övrigt vetenskapligt)
  • 122880.
    Westin, Jonas
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap, Transport- och lokaliseringsanalys. KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Centra, Centrum för transportstudier, CTS.
    Franklin, Joel
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap, Transport- och lokaliseringsanalys. KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Centra, Centrum för transportstudier, CTS.
    Grahn-Voorneveld, Sofia
    Proost, Stef
    How to decide on regional infrastructure to achieve intra-regional acceptability and inter-regional consensus?2012Ingår i: Papers in regional science (Print), ISSN 1056-8190, E-ISSN 1435-5957, Vol. 91, nr 3, s. 617-643Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Many regions face through-traffic that causes local negative externalities. Regions might respond by imposing user charges or investing in bypass transport infrastructure. In this paper two levels of decision-making are studied: co-operation among regions and acceptability within regions. If left to a single region, it will overcharge for usage and under-invest in bypass capacity. Through interregional co-operation, an efficient outcome can be reached. Without compensation within each region, intraregional acceptability constraints protecting certain interest groups can lead to inefficient tolling. This can explain political preferences for tolling bypasses and not city centre roads.

  • 122881.
    Westin, Jonas
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap. Centre for Regional Science, Umeå University.
    Franklin, Joel
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap, Transport- och lokaliseringsanalys. KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap, Transportplanering, ekonomi och teknik.
    Proost, Stef
    KU Leuven.
    Basck, Pierre
    LET, Université de Lyon.
    Raux, Charles
    LET, Université de Lyon.
    Achieving political acceptability for new transport infrastructure in congested urban regions2016Ingår i: Transportation Research Part A: Policy and Practice, ISSN 0965-8564, E-ISSN 1879-2375, Vol. 88, s. 286-303Artikel i tidskrift (Refereegranskat)
  • 122882.
    Westin, Jonas
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Centra, Centrum för transportstudier, CTS. KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap, Transport- och lokaliseringsanalys.
    Franklin, Joel
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Centra, Centrum för transportstudier, CTS. KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap, Transport- och lokaliseringsanalys.
    Proost, Stefaan
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap, Transport- och lokaliseringsanalys.
    Basck, Pierre
    Raux, Charles
    Achieving political acceptability for new transport infrastructure in congested urban regions2013Konferensbidrag (Refereegranskat)
    Abstract [en]

    Many urban regions contemplate investing in peripheral roadways that bypass the city centre in order to alleviate congestion, improve local environment and facilitate more efficient travel across the greater metropolitan areas. Increasingly, such proposals are accompanied by tolling as a means of finance. Indeed, an optimal policy from an efficiency point of view would be to consider tolling both the bypass and the existing central roadway that is relieved. However, this may be blocked by stakeholders and voter groups, or indeed never proposed to begin with.

    The rarity of congestion pricing implementations, despite supportive economic arguments, has led to a considerable body of literature ranging from equity issues (e.g. Giuliano, 1994), to privacy (e.g. Ogden, 2001), and most recently, to acceptability aspects (e.g. Schade & Schlag, 2003), where the specific factors influencing voters and decision-makers, as well as the effects of acceptability on transport policy, take centre stage. Still, few papers (e.g. Levinson, 2001; de Borger et al 2007 & 2008) have systematically examined the political economic circumstances surrounding acceptability of road pricing, and none to our knowledge has addressed the possible role of special interest groups.

    The paper analyzes the political acceptability of policies targeted at relieving urban congestion. The paper combines a stylized model of an urban transport network with a somewhat more detailed model of the political process that incorporates interactions between voters, special interest groups and politicians to explore the possibilities to reach political acceptability for efficient transport policies. In a case study of a proposed bypass in Lyon, France, the paper compares a set of potential policies in terms of efficiency, equity and political acceptability.

    The analysis suggests that the difficulty to achieve political support for efficient road pricing policies is not because optimal tolling cannot get majority support; instead the difficulty arises because conflicting interests make other non-efficient policies more attractive to many decision makers. In order to achieve political acceptability for efficient road pricing, more attention therefore needs to be placed on how the political process can resolve the inherent conflicting interests associated with efficient transport pricing policies.

  • 122883.
    Westin, Jonas
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Transportvetenskap, Transport- och lokaliseringsanalys. KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Centra, Centrum för transportstudier, CTS.
    Kågeson, Per
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Centra, Centrum för transportstudier, CTS.
    Can high speed rail offset its embedded emissions?2012Ingår i: Transportation Research Part D: Transport and Environment, ISSN 1361-9209, E-ISSN 1879-2340, Vol. 17, nr 1, s. 1-7Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper analyzes the climate implications of investments in high speed railway lines given uncertainty in future transport demand, technology and power production. To capture the uncertainty of estimated parameters, distributions for the annual traffic emissions reduction required to compensate for the embedded emissions from the construction of infrastructure are calculated using Monte Carlo simulation. In order to balance the annualized emissions from the railway construction, traffic volumes of more than 10 million annual one-way trips are usually required. Most of the traffic diverted from other modes must come from aviation and the project cannot involve the extensive use of tunnels.

  • 122884.
    Westin, Jonas
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE).
    Vierth, I.
    de Jong, G.
    Karlsson, R.
    Krüger, N. A.
    Johansson, M.
    Analyzing model uncertainty and economies of scale of the Swedish National Freight model to changes in transport demand2016Ingår i: European Journal of Transport and Infrastructure Research, ISSN 1567-7133, E-ISSN 1567-7141, Vol. 16, nr 4, s. 619-632Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The purpose of the paper is to analyze model uncertainty and economies of scale of the Swedish national freight transport model system Samgods to changes in its zone-to-zone base matrices. Even though economies of scale is important for freight transport, few studies analyze model uncertainty and economies of scale at a national level. Compared to many large scale network-based freight models working on aggregated transport flows, an important feature in Samgods is that it simulates logistics behavior at a disaggregated firm level. The paper studies effects on total tonne- and vehicle-kilometre, modal split, consolidation and logistics costs when the base matrices are scaled up and down and estimates economies of scale for Swedish freight transports. The results indicate that the logistics model can find new logistics solutions for larger demand volumes, mainly by shifting freight to sea transport. If transport volume increases with one percent, average logistics cost per tonne is reduced by around 0.5 percent. Part of the cost reduction comes from increased consolidation of shipments due to larger transport volumes. The results derived in the paper can serve as a reference for empirical validation and comparisons with other large scale freight models. The paper is a first contribution that tries to fill the knowledge gap on the impact of base matrices on transport model outcomes, such as economies of scale, in the context of a full-fledged real-world freight transport model.

  • 122885. Westin, K. J.
    et al.
    Rasmuson, Åke C.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Teknisk strömningslära.
    Nucleation of calcium carbonate in presence of citric acid, DTPA, EDTA and pyromellitic acid2005Ingår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 282, nr 2, s. 370-379Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The influence of four calcium complexing additives, i.e., citric acid (CIT), diethylenetriaminepentaacetic acid (DTPA), ethylenediaminetetraacetic acid (EDTA) and pyromellitic acid (PMA), and their concentration on the induction time of calcium carbonate nucleation has been studied. The experiments were performed by rapidly mixing a sodium carbonate solution and a calcium chloride solution of various concentrations. The induction time was obtained by recording the white light absorption of the solution. Chemical speciation was used to estimate the initial thermodynamic driving force of each experiment. The induction time was found to increase with additive concentration. The effect varies from one additive to another. CIT causes the greatest increase in induction time and PMA the least. Using classical nucleation theory the experimental data were evaluated in terms of the interfacial energy. fit pure water a value of 37.8 mJ m(-2) was obtained, showing good agreement with other works. CIT DTPA and EDTA caused a notable increase of the interfacial energy at a concentration of 0.5 mmol l(-1). PMA does not appear to have any effect at all on the interfacial energy. Different mechanisms for the influence of the additives on the measured induction time and on the estimated interfacial energy are discussed.

  • 122886. Westin, K. J.
    et al.
    Rasmuson, Åke C.
    KTH, Tidigare Institutioner                               , Kemiteknik.
    Precipitation of calcium carbonate in the presence of citrate and EDTA2003Ingår i: Desalination, ISSN 0011-9164, E-ISSN 1873-4464, Vol. 159, nr 2, s. 107-118Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The influence of process conditions such as feed rate, calcium/carbonate ratio, pH, complexing agents [ethylenediaminetetraacetic acid (EDTA), citrate (CIT)] and their concentration on the average particle size and shape of precipitated calcium carbonate was studied. The precipitation was performed in a semi-batch operated agitated vessel at constant pH by adding sodium hydrogen carbonate to a solution containing calcium chloride. In the absence of a complexing agent, agglomerates of needle-shaped crystals, probably aragonite, are obtained. Increasing feed time and the calcium/carbonate ratio increases the average particle size, whereas the opposite effect is observed for increasing pH. The observations can be related to the level of supersaturation. In the presence of complexing agents and at a concentration ratio of calcium vs. a complexing agent of 6, differently shaped and smaller particles were obtained. Furthermore, the effect of the other parameters on particle size becomes much weaker in the presence of complexing agents. In the presence of EDTA mostly spherical particles were obtained, and in the presence of citrate mainly rhombic particles corresponding to calcite were obtained. The effect on particle shape and size is attributed to interactions of the complexing agents with the faces of the crystalline calcium carbonate.

  • 122887. Westin, K. -J
    et al.
    Rasmuson, Åke Christoffer
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik.
    Precipitation of calcium carbonate in the presence of citrate and EDTA2003Ingår i: Desalination, Vol. 159, nr 2, s. 107-118Artikel i tidskrift (Refereegranskat)
  • 122888. Westin, K.
    et al.
    Rasmuson, Åke C.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Teknisk strömningslära.
    Crystal growth of aragonite and calcite in presence of citric acid, DTPA, EDTA and pyromellitic acid2005Ingår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 282, nr 2, s. 359-369Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The influence of four calcium complexing substances. i.e., citric acid (CIT). diethylenetriaminepentaacetic acid (DTPA), ethylenedi- aminetetraacetic acid (EDTA) and pyromellitic acid (PMA), oil the crystal growth rate of the calcium carbonate polymorphs aragonite and calcite has been studied. Using a seeded constant supersaturation method supersaturation was maintained at 4 by keeping a constant pH of 8.5 through addition of sodium carbonate and calcium chloride solutions. The unique composition of each solution was calculated using chemical speciation. The growth rate was interpreted in terms of an overall growth rate. For both calcite and aragonite, the crystal growth rate is significantly reduced in the presence of the calcium complexing substances. The growth retarding effect depends on both the concentration and the polymorph. The relative crystal growth rate was correlated to the total complexing agent concentration using a Langmuir adsorption approach. Aragonite appeared fully covered for lower total concentrations than calcite. Furthermore, CIT very efficiently blocked aragonite growth contrary to what was observed for calcite. This is thought to be related to certain distinct features of the dominant aragonite crystal faces compared to the dominant calcite faces.

  • 122889.
    Westin, Karl-Johan
    KTH, Tidigare Institutioner                               , Kemiteknik.
    Calcium Carbonate Precipitation in Presence of Carboxylic Acids2003Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    With a metal removal process based on precipitation aimed atthe purification of pulping effluent as a starting point, theinfluence of carboxylic acids on calcium carbonateprecipitation has been studied. The chosen carboxylic acids canact as more or less strong complexing agents for aqueouscalcium, just as many compounds found in pulping liquors.Several different experimental techniques were employed inorder to address, but also enable a distinction betweendifferent physical and chemical phenomena. Batch experimentswere used to investigate nucleation phenomena. Seeded crystalgrowth experiments with a constant thermodynamic driving forceapproach were conducted. The influence of process parameterssuch as temperature and pH was studied using semi-batchexperiments under pH-controlled as well as pH-drift conditions.The results were evaluated using a thermodynamic driving forceobtained from chemical speciation calculations.

    The results show that the chosen carboxylic acids have asignificant effect on almost every aspect of the precipitationof calcium carbonate. As a consequence they affect productproperties and significantly reduce yield. The batchexperiments revealed that the nucleation rate significantlydecreases in the presence of carboxylic acids at equal drivingforce. Yet, it varies from one acid to another. Crystal growthis also significantly retarded by the presence of carboxylicacids. The semi-batch experiments clearly showed that theability to control product properties diminishes in thepresence of the chosen carboxylic acids. The fact that theparticle shape is affected can be taken as evidence of theinteractions of the carboxylic acids with calcium carbonatebeing specific.

    The observed phenomena are interpreted as being the resultof the carboxylic acids interacting with the surface of thegrowing crystals of calcium carbonate and thereby blocking theaddition of further ions into the crystal lattice. Evidence ofthese interactions being specific was also found by linking thestructure of the crystal surfaces to features of the chosencarboxylic acids. It is also suggested that the carboxylicacids counteract processes leading to the formation ofpre-crystalline structures in the solution.

    A consequence of these findings for the envisioned metalremoval process is that it presents a great difficulty toovercome the problems related to the retardation ofprecipitation by the presence of carboxylic acids.

    Keywords:Calcium carbonate; Precipitation;Crystallization; Carboxylic Acids; Crystal Growth; Nucleation;Calcite; Aragonite; Kraft pulping; Non-Process Elements

  • 122890.
    Westin, Karl-Johan
    KTH, Tidigare Institutioner                               , Kemiteknik.
    On the removal of calcium by carbonate precipitation in sulfate pulp mills2000Licentiatavhandling, monografi (Övrigt vetenskapligt)
  • 122891.
    Westin, Kim
    KTH, Skolan för industriell teknik och management (ITM), Industriell ekonomi och organisation (Inst.), Industriell Management. Center for Technology in Medicine and Health (CTMH).
    Personalintern Kommunikation: En kartläggning av formella och informella strukturer vid hematologisk slutenvård2015Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    De senaste årens utveckling inom informationsteknik har påverkat organisationers struktur och arbetsmönster. Inom sjukvården har därför av flera anledningar behovet att studera olika former av kommunikation lyfts fram. Ur patientsäkerhetssynpunkt har problem med misstag kopplade till bristande informationsöverföring påtalats. Hierarkiska skillnader, otydliga roller och brister i själva informationsflödena har angetts som orsaker. Motåtgärderna är inte självklara. Sjukvården är en av samhällets mest komplexa kunskapsorganisationer och präglas av karaktärsdrag och informationsflöden kopplade till starka professioner.

    Kommunikationsgranskningar genomförs vanligen med målet att identifiera orsaker till ineffektiv kommunikation, brister i kommunikationsprocesser, föreslå förbättringar och ge ledning och medarbetare en mer objektiv bild av faktiska förhållanden. Forskningsområdet har dominerats av stora enkätstudier men en ökad efterfrågan har riktats mot studier på plats i den dagliga kommunikationsmiljön hos organisationer. I detta arbete har en sådan fallstudie utförts vid avdelningen för hematologisk slutenvård inom Karolinska Universitetssjukhuset i Huddinge, Stockholm. Avdelningen hade år 2012 i samband med ett lokalbyte inom sjukhuset genomfört omstruktureringar som berörde såväl roller som kanalerna för kommunikation. Verksamheten upplevdes nu inte bedrivas tillräckligt effektiv, den uppfattades ta tid och vara oöverskådlig där förbättrad kommunikation sågs som en lösning. Syftet med denna fallstudie har varit att utifrån roller och kanaler för kommunikation belysa aspekter på hur en tydligare formell struktur för dagens personalinterna kommunikation kan skapas och förmedlas.

    Syftet besvarades genom att kartlägga dagens formella struktur, vilket är det förväntade utbytet av information beskrivet i arbetsbeskrivningar och policys, men även genom att studera den informella struktur som utvecklats i det dagliga arbetet. En blandning av datainsamlingsmetoder har använts och organisationens kommunikationsnätverk i form av det nätverk som byggs upp av flödet av information mellan aktörer har visualiserats och analyserats. Resultatet visar på skillnader mellan den formella strukturen för personalintern kommunikation och den informella strukturen. Dessa har använts för att analysera, diskutera och föreslå hur de identifierade skillnaderna kan användas för att förtydliga roller och kanaler i den formella strukturen.

    Studien har identifierat sex områden där den formella strukturen kan förtydligas; en högre grad av dokumenterat kommunikativt ansvar och tydliga rutiner, en stärkt kommunikation inom arbetsteam istället för inom professioner, en definition av över-­‐ och underläkarnas kommunikativa roller, en ökad kontinuitet i centrala roller för kommunikation, en översyn av den fysiska strukturens påverkan på kommunikationen och slutligen ökade förutsättningar för snabb direkt kommunikation med informationsteknologi. 

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  • 122892. Westin, Linda
    et al.
    Akkuratov, Evgeny E.
    De Marothy, Minttu
    Lindskog, Maria
    Brismar, Hjalmar
    KTH, Centra, Science for Life Laboratory, SciLifeLab. KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik. Karolinska Inst, Sci Life Lab, Solna, Sweden.
    Aperia, Anita
    Instantaneous Down-Regulation of NMDA Receptor Activity by Nanomolar Concentrations of Ouabain2017Ingår i: The FASEB Journal, ISSN 0892-6638, E-ISSN 1530-6860, Vol. 31Artikel i tidskrift (Övrigt vetenskapligt)
  • 122893. Westin, Linda
    et al.
    Reuss, Matthias
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik. KTH, Centra, Science for Life Laboratory, SciLifeLab.
    Lindskog, Maria
    Aperia, Anita
    Brismar, Hjalmar
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Cellens fysik. KTH, Centra, Science for Life Laboratory, SciLifeLab.
    Nanoscopic spine localization of Norbin, an mGluR5 accessory protein2014Ingår i: BMC neuroscience (Online), ISSN 1471-2202, E-ISSN 1471-2202, Vol. 15, s. 45-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Background: Norbin is a neuron-specific, cytosolic protein that interacts with the metabotropic glutamate receptor 5 (mGluR5) and has a profound impact on mGluR5 signaling. Yet, little is known about its synaptic distribution. Results: Here we have analyzed the spatial relationship between Norbin, postsynaptic density protein 95 (PSD-95), actin and mGluR5 in spines using super-resolution microscopy. Norbin was found to have a high degree of colocalization with actin and a lower degree of colocalization with PSD-95. Co-immunoprecipitation studies confirmed that interaction occurs between Norbin and actin, but not between Norbin and PSD-95. Norbin was also found to have a high degree of colocalization with the perisynaptically located mGluR5. Findings based on structured illumination microscopy (3D-SIM) of exogenous expressed Norbin-GFP were confirmed by stimulated emission depletion microscopy (STED) of immunolabeled endogenous Norbin. Conclusions: Norbin associates with actin rather than with PSD-95 in dendritic spines. Results regarding protein localization and colocalization performed with conventional confocal microscopy must be interpreted with great caution. The now available super-resolution microscopy techniques provide more accurate information about sub-cellular protein localization than previously was possible.

  • 122894.
    Westin, Lucas
    et al.
    KTH, Skolan för teknikvetenskap (SCI).
    Söderberg, Jimmy
    KTH, Skolan för teknikvetenskap (SCI).
    Ljudreduktion i ventilationskanaler2019Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Denna rapport för kandidatexamensarbete inom ljud och vibrationer riktar sig åt att undersöka beteendet av ljudreduktion för låga frekvenser och se när brytpunkten för så kallat breakout noise uppstår. Fokus ligger kring huruvida det finns en mättnad i ljudreduktion, enligt teori, på 6 dB per meter av ljuddämpare under 250 Hz. Ljuddämparen som används i projektet är CLA-A-250 från Swegon. Projektet kom till liv från företaget LN Akustikmiljö då de upplevde ett annat dämpningsbeteende än just det. Mätningarna för projektet tog plats i MWL-laboratoriet på KTH. Som kan åskådas i resultatet visar det sig att antagandet om 6 dB dämpning per meter av ljuddämpare är felaktigt. Gällande breakout noise så är det tydligt att så länge kanalstrukturen och dess utlopp är i skilda rum så är det inte ett problem. Dessa slutsater är säkra att göra på grund av användandet av standarder och marginaler som togs hänsyn till i beräkningar och mätningar. Projektet var en bra insikt i hur en period i yrkeslivet kan se ut för en akustiker.

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  • 122895.
    Westin, Mari
    KTH, Tidigare Institutioner                               , Kemiteknik.
    Aspects on multi-institutional international collaboration as a method for technical development2002Licentiatavhandling, monografi (Övrigt vetenskapligt)
  • 122896. Westin, Mats
    et al.
    Larsson Brelid, Pia
    Segerholm, Kristoffer
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Van den Oever, M.
    Wood Plastic Composites from Modified Wood: Part 3. Durability of WPCs with bioderived matrix2008Ingår i: The 39th Annual Meeting of the International Research Group on Wood Preservation, 2008Konferensbidrag (Refereegranskat)
    Abstract [en]

    The decay resistance of fully bio-derived wood plastic composites, WPCs, was tested in bothlaboratory and field tests. The laboratory tests were performed according to modified versionsof AWPA E10 (soil-block test) and ENV 807 (tests in three un-sterile soils) and the field testsaccording to EN 252 (stakes in ground) and EN 275 (resistance to marine borers). The WPCmaterials for laboratory tests were injection molded test specimens with 50% modified woodparticles and 50% cellulose ester (CAP) or poly-lactic acid (PLA) content. The field testspecimens were taken from larger extruded decking board profiles with 60% wood contentand 40% CAP. 60/40-mix (wt/wt) for CAP corresponds to the same volumetric compositionas 70/30-mix (wt/wt) with polypropylene as matrix that was presented in Part 1 and 2.In all laboratory tests the control WPCs performed much better than the pine sapwood controlblocks. The WPCs from modified wood performed better than the control WPC and WPCsfrom acetylated wood performed best with no detectable decay whatsoever.In the field stake test, the WPC from unmodified wood were slightly decayed whereas theWPCs from modified wood were sound. In the marine field test the WPC from unmodifiedwood were severely attacked by shipworm (Teredo navalis), whereas the WPCs frommodified wood were sound.

  • 122897.
    Westin, Mikael
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Arkitektur.
    ArkiNatur2012Självständigt arbete på avancerad nivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Detta projekt åskådliggör ett alternativ till hur människan i framtiden skall kunna uppleva den svenska naturen och ta vara på regioner som sakta förfaller och ödeläggs på grund av den rådande urbaniseringen.

    Projektet har ett övergripande koncept vari tre detaljerade lösningar visar hur det tekniskt kan genomföras. 

    Genom att ta vara på de befintliga förutsättningarna, regionens infrastruktur, de olika årstiderna i den fantastiska omgivningen, visas ett nytt sätt att turista i naturen

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    ArkiNatur
  • 122898.
    Westin, Ola
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    TCP Performance in Wireless Mobile Multi-hop Ad Hoc Networks2003Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Många faktorer begränsar prestandan i trådlösa mobila multi-hopp ad hoc-nätverk (MANET:er). En av dem är att TCP inte är anpassat till nätverk där rutter ofta kan förändras eller försvinna. I den här rapporten studeras hur en vanlig TCP-implementation uppför sig i typiska MANET-situationer. Detta beteende jämförs mot en partiell implementation av ATCP, en TCPmodifiering som är tänkt att öka prestanda i MANET:er.

    Simuleringar med enkla scenarier visar att TCP lätt genererar en full nätverkslast vilket orsakar misslyckade sändningar och en minskad genomströmningsprestanda. I vissa fall ökar den partiella ATCP-implementationen genomströmningen, men oftare ger den en ökad mängd onödiga omsändningar. I dessa scenarier är det inte troligt att ens en komplett ATCP-implementation skulle öka genomströmningsprestanda.

    Några mindre förändringar av ATCP och TCP analyseras. Särskilt ger en begränsning av stockningsfönstret en stor ökning av genomströmningen. Resultaten är ofullständiga. Simuleringarna är för enkla för att kunna visa om om resultaten är tillämpliga i mer komplexa scenarier. Det är inte klarlagt ifall ATCP verkligen är användbart i ett MANET.

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  • 122899.
    Westin, Robert
    KTH, Skolan för teknikvetenskap (SCI).
    Visualization of sports performance data on Androidmobile-phone acquired through a Bluetooth link2012Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Recent developments in mobile architecture and the need for objective performance

    measurement in kayak elite sport coaching induced the opportunity for this study. We

    developed an application for smartphones that will help athletes evaluate their perfor-

    mance. Several sensors measure forces, acceleration and distance. Data is sent through

    a wireless connection and stored in a smartphone. The aim of this study is to evalu-

    ate technical possibilities on the smartphone in a coaching environment by comparing

    previous system proposals, to evaluate the learning situation when using the device

    as technical aid based on learning theories and technical limitations, and to design

    visualizations on the mobile device according to technical possibilities and learning

    theories. Technical research is used as a framework to compare the proposed system

    design to others, in sense of components used and the devices’ technical possibilities.

    Feedback-theory is used to explain the learning of motor skills and theory about visual

    literacy in the understanding of visualizations. Last cognitive models from Cognitive

    Load Theory (CLT), Multimedia Learning (ML) and Human Computer Interaction

    (HCI) are presented.

    Visualizations on Android smartphones are limited by screen size and navigation

    possibilities. The challenge for the athlete and coach is to see patterns in acquired

    data and to translate it to manageable exercises suitable for the motor skill domain.

    In the motor skill domain it is important for the athlete to understand what behavior,

    e.g. what element of a movement to learn or improve. In current system designs the

    athlete has to wait a long time between performance and feedback. The athlete has to

    remember a long series of movements and match it with measured data, which could

    be ineffective according CLT.

    The design of feedback will depend on the learning situation, technical possibilities

    and the information to process. When the environment is cognitively demanding the

    visualization should be easy to understand and the information easy to apprehend.

    Complex data could be presented in a graph on the mobile device but a big screen is

    recommended for this. The technical possibilities with the Android platform are suffi-

    cient for the intended use. Direct feedback in real-time is preferred to post-visualization

    in motor skill exercises.

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    Robert Westin, Civilingenjör och Lärare, examensarbete
  • 122900.
    Westin Sandström, Malin
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Arkitektur.
    Rum i park: En verksamhet med fokus på barn och ungdomar2011Självständigt arbete på avancerad nivå (yrkesexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Examensarbetet utvecklar en miljö för barn och ungdomar i olika åldersgrupper, där både inne- och uterum är av lika stor vikt. Vidare utvecklar projektet gestaltningen och användningen av en befintlig park i Stockholm.

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