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  • 201.
    Aichmayer, Lukas
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Solar receiver development for gas-turbine based solar dish systems2018Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [sv]

    Småskalig koncentrerad solkraft som mikrogasturbinbaserade solkraftverk med paraboliska solfångare visar potential att utnyttja solens energi på ett effektivt sätt och levererar el till kunder i avlägsna områden. I dessa solkraftverk är det solmottagaren som överför energin av koncentrerat solljus till kraftomvandlingssystemets arbetsmedium. Mottagaren är en av de viktigaste komponenterna eftersom den drivs vid höga temperaturer för att nå en hög systemverkningsgrad och är utsatt för höga ljusintensiteter för att nå en hög komponentverkningsgrad. För att hantera dessa utmaningar och garantera en effektiv och pålitlig drift behövs nya och innovativa lösningar.

    Syftet med detta arbete är att utveckla en solmottagare genom att använda en systematisk design- och analysmetodik. Därför utvecklades en omfattande design- och analysprocess som inkluderar identifiering av tekniska specifikationer, utveckling av designverktyg för olika detaljnivåer i samband med optimeringsmetoder, utvärdering av skalningseffekter mellan laboratorietester och fullskaliga tester. Som resultatet av designprocessen konstruerades en solmottagare för den experimentella utvärderingen där alla materialtemperaturer och materialspänningar är inom tillåtna nivåer.

    Den experimentella utvärderingen inkluderar förbättringarna av KTH:s solsimulator för att säkerställa stabil och pålitlig drift, karakterisering av instrålningen, utveckling av en solmottagartestbädd, och solmottagarexperiment för olika driftspunkter. Resultaten visar att solmottagaren uppnår en verkningsgrad på 69.3% för en luftutloppstemperatur på 800°C och ett massflöde på 29.5 g/s. Verkningsgraden ökar till 84.8% för ett massflöde på 40 g/s med en luftutloppstemperatur på 749°C.

    De experimentella resultaten användes för att validera de utvecklade solmottagardesignverktygen genom en flerpunktsvalideringsprocess vilket resulterar i ett högt förtroende av designverktygens noggrannhet. De validerade designverktygen användes för att beräkna prestandan av en fullskalig solmottagare för integreringen i OMSoP solkraftverket. Resultaten visar att konceptet uppnår en luftutloppstemperatur på 800°C med en verkningsgrad på 82.5%.

    Till sist undersöktes den ekonomiska potentialen av mikrogasturbinbaserade solkraftverk. De teknoekonomiska analyserna visar att kraftverken är ideal för småskaliga off-grid applikationer.

    Resultaten av solmottagarutvecklingen framhäver möjligheten att använda volumetriska solmottagare för att leverera värme till mikrogasturbinbaserade solkraftverk med paraboliska solfångare och inga stora problem upptäcktes.

  • 202.
    Aichmayer, Lukas
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Garrido, Jorge
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Laumert, Björn
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Performance Improvements of the KTH High-Flux Solar Simulator2017Ingår i: AIP Conference Proceedings 1850, American Institute of Physics (AIP), 2017, Vol. 1850, artikel-id 150001Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents the performance improvements implemented in the KTH high-flux solar simulator to deliver a total power on target closer to the working conditions of real CSP systems. Therefore, additional rectifiers were installed in the power conversion unit of the high-power lamps as well as the back reflector was coated providing more favorable spectral reflectance properties. The results of a single lamp/lens-combination show that the power on target in an aperture of 280mm in diameter was increased from 831W to 1446W while the peak flux was increased from 675kW/m² to 905kW/m².

  • 203.
    Aichmayer, Lukas
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Garrido, Jorge
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Laumert, Björn
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Scaling effects of a novel solar receiver for a micro gas-turbine based solar dish system2018Ingår i: International Journal of Solar Energy, ISSN 0142-5919, E-ISSN 1477-2752, Vol. 162, s. 248-264Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Laboratory-scale component testing in dedicated high-flux solar simulators is a crucial step in the developmentand scale-up of concentrating solar power plants. Due to different radiative boundary conditions available inhigh-flux solar simulators and full-scale power plants the temperature and stress profiles inside the investigatedreceivers differ between these two testing platforms. The main objective of this work is to present a systematicscaling methodology for solar receivers to guarantee that experiments performed in the controlled environmentof high-flux solar simulators yield representative results when compared to full-scale tests. In this work theeffects of scaling a solar air receiver from the integration into the OMSoP full-scale micro gas-turbine based solardish system to the KTH high-flux solar simulator are investigated. Therefore, Monte Carlo ray-tracing routines ofthe solar dish concentrator and the solar simulator are developed and validated against experimental characterizationresults. The thermo-mechanical analysis of the solar receiver is based around a coupled CFD/FEManalysislinked with stochastic heat source calculations in combination with ray-tracing routines. A geneticmulti-objective optimization is performed to identify suitable receiver configurations for testing in the solarsimulator which yield representative results compared to full-scale tests. The scaling quality is evaluated using aset of performance and scaling indicators. Based on the results a suitable receiver configuration is selected forfurther investigation and experimental evaluation in the KTH high-flux solar simulator.

  • 204.
    Aichmayer, Lukas
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Spelling, James
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Laumert, Björn
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Preliminary design and analysis of a novel solar receiver for a micro gas-turbine based solar dish system2015Ingår i: Solar Energy, ISSN 0038-092X, E-ISSN 1471-1257, Vol. 114, nr 4, s. 378-396Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The solar receiver is one of the key components of hybrid solar micro gas-turbine systems, which would seem to present a number of advantages when compared with Stirling engine based systems and photovoltaic panels. In this study a solar receiver meeting the specific requirements for integration into a small-scale (10 kWel) dish-mounted hybrid solar micro gas-turbine system has been designed with a special focus on the trade-offs between efficiency, pressure drop, material utilization and economic design. A situation analysis, performed using a multi-objective optimizer, has shown that a pressurized configuration, where the solar receiver is placed before the turbine, is superior to an atmospheric configuration with the solar receiver placed after the turbine. Based on these initial design results, coupled CFD/FEM simulations have been performed, allowing detailed analysis of the designs under the expected operating conditions. The results show that the use of volumetric solar receivers to provide heat input to micro gas-turbine based solar dish systems appears to be a promising solution; with material temperatures and material stresses well below permissible limits.

  • 205.
    Aichmayer, Lukas
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Spelling, James
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Laumert, Björn
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Small Scale Hybrid Solar Power Plants for Polygeneration in Rural Areas2014Ingår i: Energy Procedia 57, Elsevier, 2014, Vol. 57, s. 1536-1545Konferensbidrag (Refereegranskat)
    Abstract [en]

    Small scale micro gas-turbine based hybrid solar power plants are a promising technology for supplying multiple energy services in a controllable and sustainable manner using polygeneration technologies. Compared to a conventional diesel generator based system where electricity is used as the main energy carrier, these systems show great potential to reduce costs and carbon dioxide emissions. Depending on the design, carbon dioxide emissions are reduced by around 9% and equivalent annual costs are reduced by 21% - 26%, as compared to a base polygeneration configuration where cooling services are provided centrally by an absorption chiller without integrating a solar micro gas-turbine. Compared to the system where electricity is used as the main energy carrier a reduction of equivalent annual costs of up to 20% and a reduction of carbon dioxide emissions of up to 33.5% was achieved.

  • 206.
    Aichmayer, Lukas
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Spelling, James
    IMDEA Energy Institute, Spain.
    Laumert, Björn
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Thermoeconomic Analysis of a Solar Dish Micro Gas-Turbine Combined-Cycle Power Plant2015Ingår i: Energy Procedia 69, Elsevier, 2015, Vol. 69, s. 1089-1099Konferensbidrag (Refereegranskat)
    Abstract [en]

    A novel solar power plant concept is presented, based on the use of a coupled network of hybrid solar-dish micro gas-turbines, driving a centralized heat recovery steam generator and steam-cycle, thereby seeking to combine the high efficiency of the solar dish collector with a combined-cycle power block. A 150 MWe solar power plant was designed based on this concept and compared with both a conventional combined-cycle power plant and a hybrid solar-tower combined-cycle. The solar dish combined-cycle power plant could reach higher levels of solar integration than other concepts but was shown to be more expensive with current technology; solar electricity costs are double those of the hybrid solar-tower combined cycle.

  • 207.
    Aichmayer, Lukas
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Spelling, James
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Laumert, Björn
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Micro Gas-Turbine Design for Small-Scale Hybrid Solar Power Plants2013Ingår i: Proceedings of the ASME Turbo Expo 2013. San Antonio, USA. June 3-7, ASME , 2013Konferensbidrag (Refereegranskat)
    Abstract [en]

    Hybrid solar micro gas-turbines are a promising technology for supplying controllable low-carbon electricity in off-grid regions. A thermoeconomic model of three different hybrid micro gas-turbine power plant layouts has been developed, allowing their environmental and economic performance to be analyzed. In terms of receiver design, it was shown that the pressure drop is a key criterion. However, for recuperated layouts the combined pressure drop of the recuperator and receiver is more important. The internally-fired recuperated micro gas-turbine was shown to be the most promising solution of the three configurations evaluated, in terms of both electricity costs and carbon emissions. Compared to competing diesel generators, the electricity costs from hybrid solar units are between 10% and 43% lower, while specific CO2 emissions are reduced by 20 – 35%.

  • 208.
    Aichmayer, Lukas
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Spelling, James
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Laumert, Björn
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Fransson, Torsten
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Micro Gas-Turbine Design for Small-Scale Hybrid Solar Power Plants2013Ingår i: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 135, nr 11, s. 113001-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Hybrid solar micro gas-turbines are a promising technology for supplying controllable low-carbon electricity in off-grid regions. A thermoeconomic model of three different hybrid micro gas-turbine power plant layouts has been developed, allowing their environmental and economic performance to be analyzed. In terms of receiver design, it was shown that the pressure drop is a key criterion. However, for recuperated layouts, the combined pressure drop of the recuperator and receiver is more important. In terms of both electricity costs and carbon emissions, the internally-fired recuperated micro gas-turbine was shown to be the most promising solution of the three configurations evaluated. Compared to competing diesel generators, the electricity costs from hybrid solar units are between 10% and 43% lower, while specific CO2 emissions are reduced by 20–35%.

  • 209.
    Aichmayer, Lukas
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Spelling, James
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Wang, Wujun
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Laumert, Björn
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Design and Analysis of a Solar Receiver for Micro Gas Turbine based Solar Dish Systems2012Ingår i: Proceedings of the International SolarPACES Conference 2012. Marrakesh, Morocco. September 11-14, 2012, 2012Konferensbidrag (Refereegranskat)
    Abstract [en]

    The solar receiver is one of the key components of hybrid solar micro gas turbine systems which would seem to present a number of advantages when compared with Stirling engine systems. A solar receiver meeting the specific requirements for integration into the power conversion system of the solar laboratory of the Royal Institute of Technology - which will emulate a solar dish system and is currently under construction - was designed. The simulations that have been performed utilize a heat transfer and pressure drop model coupled with a multi-objective optimizer as well as a coupled-CFD/FEM tool, allowing determination of the ideal receiver design for the expected conditions. The analysis has shown that the use of volumetric solar receivers to provide heat input to micro gas turbine based solar dish systems appears to be a promising solution; with pressurized receiver configurations as the preferred choice due to significant lower pressure drops as compared to atmospheric configurations.

  • 210.
    Aichmayer, Lukas
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Wang, Wujun
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Garrido, Jorge
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Laumert, Björn
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Experimental evaluation of a novel solar receiver for a micro gas-turbine based solar dish system in the KTH high-flux solar simulator2018Ingår i: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 159, s. 184-195Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This work presents the experimental evaluation of a novel pressurized high-temperature solar air receiver for the integration into a micro gas-turbine solar dish system reaching an air outlet temperature of 800°C. The experiments are conducted in the controlled environment of the KTH high-flux solar simulator with well-defined radiative boundary conditions. Special focus is placed on providing detailed information to enable the validation of numerical models. The solar receiver performance is evaluated for a range of operating points and monitored using multiple point measurements. The porous absorber front surface temperature is measured continuously as it is one of the most critical components for the receiver performance and model validation. Additionally, pyrometer line measurements of the absorber and glass window are taken for each operating point. The experiments highlight the feasibility of volumetric solar receivers for micro gas-turbine based solar dish systems and no major hurdles were found. A receiver efficiency of 84.8% was reached for an air outlet temperature of 749°C. When using a lower mass flow, an air outlet temperature of 800°C is achieved with a receiver efficiency of 69.3%. At the same time, all material temperatures remain below permissible limits and no deterioration of the porous absorber is found.

  • 211.
    Aichmayer, Lukas
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Wang, Wujun
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Garrido, Jorge
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Laumert, Björn
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Experimental Flux Measurement of a High-Flux Solar Simulator using a Lambertian Target and a Thermopile Flux Sensor2016Ingår i: AIP Conference Proceedings 1734, American Institute of Physics (AIP), 2016, Vol. 1734, artikel-id 130001Konferensbidrag (Refereegranskat)
    Abstract [en]

    A measurement system for the experimental determination of the flux distribution at the focal plane of the KTH high-flux solar simulator was designed and implemented. It is based on a water-cooled Lambertian target and a thermopile flux sensor placed close to the focal point of the solar simulator. Correction factors to account for systematic effects were determined and an uncertainty analysis was performed. The measurement system was successfully used to evaluate the flux distribution of a single lamp/lens-arrangement with a peak flux of 675kW/m².

  • 212.
    AIDANPÄÄ, MATHILDA
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Integrerad produktutveckling.
    SJÖBERG, MATHILDA
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Integrerad produktutveckling.
    De etiska konsekvenserna av produktutveckling: Oönskade konsekvenser av strävan efter zero-labourfactories2018Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Graden av automatisering sker i allt högre takt idag, vilken drivs av innovationer och produktutvecklingar. Att följa med i denna utveckling är nödvändigt för att företag ska förbli konkurrenskraftiga på marknaden. Introduktion av ny och modern teknik har gjort att frågan om vi nu står inför en fjärde industriell revolution diskuteras flitigt. Begrepp som zero-labour factory blir allt mer använt vid denna tekniska framfart. Huruvida hänsyn tas till det etiska perspektivet vid automatisering och produktutvecklingsprocesser är en fråga som blir mer aktuell.

    Syftet med denna rapport är att utreda hur stor roll det etiska perspektivet har vid beslut om automatisering och vem det etiska ansvaret ligger hos vid automatisering. Utöver detta undersöks även om etik bör integreras i ingenjörsutbildningar och till vilken utsträckning. Utifrån detta har följande frågeställningar har studerats:

    Hur stor är vikten av det etiska perspektivet i beslutsfasen vid automatisering?

    Hos vem ligger det etiska ansvaret för produktutvecklingen?

    I vilken utsträckning borde det etiska perspektivet integreras i utbildningen?

    Metoden som använts under detta arbete är en omfattande litteraturstudie av hur forskningen ser ut i dagsläget. Till det har en kvalitativ studie gjorts genom semistrukturerade intervjuer med personer som är verksamma på företag som har automatiserat sin produktion eller arbetar med att ta fram produkter i automatiseringssyfte på den svenska marknaden.

    Resultatet av studien visar att de producerande företagen strävar efter zero-labour factories och gör sitt yttersta för att ta ansvar för de etiska konsekvenserna som drabbar medarbetarna på grund av det. Trots att det råder en gemensam åsikt om att automatisering kan få oönskade etiska effekter, väljer företagen att integrera produktutvecklingar. Det är effektiviseringar och kostnadsminimeringar som är drivande faktorer, det etiska perspektivet kommer i andrahand. Vidare säger de företag som automatiserar att de tar ett etiskt ansvar för sina medarbetare, men fortsätter med automatiseringsprocesser för att förbli konkurrenskraftiga. Intervjupersonen från det produktutvecklande företag anser sig inte ha något etiskt ansvar för hur teknikutvecklingen påverkar medarbetare hos slutkunden.

    Vidare visar forskning på området att teknikutveckling kan ha oönskade etiska effekter, något som en ingenjör måste ta hänsyn till. Kungliga Tekniska högskolan har idag inte etik som obligatoriskt moment på alla dess program. Personer som intervjuats anser att det bör ingå i utbildningen, vilket även styrks av genomförd litteraturstudie.

    Slutsatser som dragits är att det etiska perspektivet inte väger tungt jämfört med kostnadsbesparingar och effektivisering av produktionen vid beslutsprocesser, att det etiska ansvaret för produktutvecklingen ligger både på det producerande och de produktutvecklande företagen samt till sist att etik bör integreras i utbildningen.

  • 213.
    Aidanpää, Sandra
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.).
    Nordmark, Elin MK
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.).
    Flexible Updates of Embedded Systems Using Containers2016Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    I denna uppsats undersöks virtualiseringslösningen Docker i samband med uppdatering på applikationsnivå i ett inbyggt system. En uppdateringsekvens är utformad, modellerad och genomförd, samt experiment genomförda för att mäta upp tid och ström. Samhället blir mer och mer uppkopplat, fler och fler saker är anslutna till Internet och därmed skapas möjligheter för dynamiska uppdateringar via Internet. Att kunna genomföra fjärruppdateringar kan vara väldigt fördelaktigt eftersom det kan vara dyrt eller opraktiskt att fysisktna system för programuppdateringar. Operativsystemnivå-virtualisering, mjukvarucontainrar, är en lättviktig virtualiseringslösning som kan användas för dynamiska uppdateringsändamål. Virtualiseringsegenskaper, såsom resursisolering och att programvara delar hårdvarufunktioner, anvands för att bestämma arkitekturen. Containerarkitekturen som används är en mikrotjänstarkitektur, där systemen är uppbyggda av många mindre, löst kopplade tjänster. Användningsområdet för resultaten av denna avhandling är nystartade företag som befinner sig i marknadsområdet för det uppkopplade samhället, begränsat till system med lag komplexitet såsom konsumentprodukter. Uppdateringssekvensen skapas med egenskaperna hos mikrotjänstarkitekturer i åtanke; en självgående, självtestande, skalbar och sömlös dynamisk uppdateringsprocess, som kan anvandas för system av olika komplexitet. Uppdateringssekvensen modelleras för att ge bevis på konceptet och för att underlätta utformningen av genomförandet. Den genomförda uppdateringssekvensen gjordes på ARM-baserad enkortsdator med ett Linux-kärnbaserat operativsystem som kör Docker. Experiment utfördes sedan för att ge en tydlig indikation på beteendet vid dynamisk uppdatering av ett inbyggt system. Experimenten visade att uppdateringssekvensen kan vara sömlös, vilket innebär att upptidegenskaperna inte påverkas av denna typ av uppdatering. Experimenten visade också att inga väsentliga förändringar i ström kan noteras för begränsningar av containern under denna typ av uppdatering.

  • 214.
    Aishwar, Ravichandran
    KTH, Skolan för teknikvetenskap (SCI).
    Aerodynamics of Bird Flight2014Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    It is the objective of this thesis project to understand the physics behind the different modes of bird flight and to do numerical two dimensional simulations of pure plunging, pure pitching and combined pitch-plunging motion of an aerofoil. First, the different physical models used to understand the generation of thrust are explained. Then the numerical model used for the simulation is explained briefly. Then the results and analysis of the numerical simulations are presented.

  • 215.
    Ajmal Khan, Muhammad
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Raza, Rizwan
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Bohn Lima, Raquel
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik. KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknik.
    Chaudhry, M. Asharf
    Ahmed, E.
    Abbas, Ghazanfar
    Comparative study of the nano-composite electrolytes based on samaria-doped ceria for low temperature solid oxide fuel cells (LT-SOFCs)2013Ingår i: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 38, nr 36, s. 16524-16531Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Ceria-based electrolyte materials have great potential in low and intermediate temperature solid oxide fuel cell applications. In the present study, three types of ceria-based nanocomposite electrolytes (LNK-SDC, LN-SDC and NK-SDC) were synthesized. One-step co-precipitation method was adopted and different techniques were applied to characterize the obtained ceria-based nano-composite electrolyte materials. TGA, XRD and SEM were used to analyze the thermal effect, crystal structure and morphology of the materials. Cubic fluorite structures have been observed in all composite electrolytes. Furthermore, the crystallite sizes of the LN-SDC, NK-SDC, LNK-SDC were calculated by Scherrer formula and found to be in the range 20 nm, 21 nm and 19 nm, respectively. These values emphasize a good agreement with the SEM results. The ionic conductivities were measured using EIS (Electrochemical Impedance Spectroscopy) with two-probe method and the activation energies were also calculated using Arrhenius plot. The maximum power density was achieved 484 mW/cm(2) of LNK-SDC electrolyte at 570 degrees C using the LiCuZnNi oxide electrodes.

  • 216.
    Akander, Jan
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap.
    Alvarez, S
    Jóhannesson, Gundi
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap.
    Energy normalization techniques2004Ingår i: Energy Performance of Residential Buildings: A Practical Guide for Energy Rating and Efficiency, James & James/Earthscan , 2004, s. 57-70Kapitel i bok, del av antologi (Övrigt vetenskapligt)
  • 217.
    Akander, Jan
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap.
    Jóhnnesson, Gudini
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap.
    Experimental methods for the energy characterization of buildings2004Ingår i: Energy Performance of Residential Buildings: A Practical Guide for Energy Rating and Efficiency, James & James/Earthscan , 2004, s. 26-56Kapitel i bok, del av antologi (Övrigt vetenskapligt)
  • 218.
    Akbarpour, S.
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg.
    Hallström, S.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg.
    Metal reinforcement around fastener holes in composites2016Ingår i: ECCM 2016 - Proceeding of the 17th European Conference on Composite Materials, European Conference on Composite Materials, ECCM , 2016Konferensbidrag (Refereegranskat)
    Abstract [en]

    One way of improving the load capacity of bolted joints in composite components is to use metal inserts locally at the holes in order to reduce the bearing stress. In this paper an innovative local reinforcement concept is introduced where metal inserts are implemented in the form of stacked patches at the holes in order to improve the bearing strength of the composite. After doing some initial tests and a parameter study, some specimens with optimized stacked patch inserts were designed and tested. The specimens with optimized inserts show 50-60% improved bearing strength in pin-loaded tests which corresponds to a potential weight reduction of about 30%. These very promising results indicates that the efficiency of joints in composites can be improved significantly.

  • 219.
    Akhlaghi, Shahin
    et al.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material. Scania CV AB, Sweden.
    Gedde, Ulf W.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    Hedenqvist, Mikael S.
    KTH, Skolan för kemivetenskap (CHE), Fiber- och polymerteknologi, Polymera material.
    Brana, Maria T. Conde
    Bellander, Martin
    Deterioration of automotive rubbers in liquid biofuels: A review2015Ingår i: Renewable & sustainable energy reviews, ISSN 1364-0321, E-ISSN 1879-0690, Vol. 43, s. 1238-1248Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Concerns over the fast depletion of fossil fuels, environmental issues and stringent legislation associated with petroleum-based fuels have triggered a shift to bio-based fuels, as an alternative to meet the growing energy demand in the transportation sector. However, since conventional automobile fuel systems are adapted to petroleum-based fuels, switching to biofuels causes a severe deterioration in the performance of currently used rubber components. The degradation of the rubber materials in biofuels is complicated by the presence of different additives in biofuels and rubber compounds, by oxidation of biofuels and by the effects of thermomechanical loadings in the engine. This paper presents a comprehensive review of the effects of different types of biofuels, particularly biodiesel and bioethanol, on the physical, mechanical, morphological and thermal properties of elastomers under different exposure conditions. In addition, the literature data available on the variation of rubbers' resistance to biofuels with the changes in their monomer type and composition, cure system and additives content was also studied. The review essentially focuses on the compatibility of biofuels with acrylonitrile butadiene rubber, fluoroelastomers, polychloroprene rubber and silicon rubber, as the most commonly used automotive rubbers coming into contact with fuels during their service. The knowledge summarized in this study can help to develop a guideline on the selection of rubber for automotive parts designed to withstand biofuels.

  • 220.
    Akillioglu, Hakan
    KTH, Skolan för industriell teknik och management (ITM), Industriell produktion, Produktionssystem.
    Demand Responsive Planning: A dynamic and responsive planning framework based on workload control theory for cyber-physical production systems2015Doktorsavhandling, monografi (Övrigt vetenskapligt)
    Abstract [en]

    Recent developments in the area of Cyber-Physical Production Systems prove that high technology readiness level is already achieved and industrialization of such technologies is not far from today. Although these technologies seem to be convenient in providing solutions to environmental uncertainties, their application provides adaptability only at shop floor level. Needless to say, an enterprise cannot reach true adaptability without ensuring adaptation skills at every level in its hierarchy. Commonly used production planning and control approaches in industry today inherit from planning solutions which are developed in response to historical market characteristics. However, market tendency in recent years is towards making personalized products a norm. The emerging complexity out of this trend obliges planning systems to a transition from non-recurring, static planning into continuous re-planning and re-configuration of systems. Therefore, there is a need of responsive planning solutions which are integrated to highly adaptable production system characteristics.

    In this dissertation, Demand Responsive Planning, DRP, is presented which is a planning framework aiming to respond to planning needs of shifting trends in both production system technologies and market conditions. The DRP is based on three main constructs such as dynamicity, responsiveness and use of precise data. These features set up the foundation of accomplishing a high degree of adaptability in planning activities. By this means, problems from an extensive scope can be handled with a responsive behavior (i.e. frequent re-planning) by the use of precise data. The use of precise data implies to execute planning activities subject to actual demand information and real-time shop floor data. Within the context of the DRP, both a continuous workload control method and a dynamic capacity adjustment approach are developed. A test-bed is coded in order to simulate proposed method based on a system emulation reflecting the characteristics of cyber-physical production systems at shop floor level.

    Continuous Precise Workload Control, CPWLC, method is a novel approach aiming at precise control of workload levels with the use of direct load graphs. Supported by a multi-agent platform, it generates dynamic non-periodic release decisions exploiting real time shop floor information. As a result, improved shop floor performances are achieved through controlling workload levels precisely by the release of appropriate job types at the right time.

    Presented dynamic capacity adjustment approach utilizes rapid re-configuration capability of cyber-physical systems in achieving more frequent capacity adjustments. Its implementation architecture is integrated to the CPWLC structure. By this means, a holistic approach is realized whereby improved due date performance is accomplished with minimized shop floor congestion. Hence, sensitivity to changing demand patterns and urgent job completions is improved.

  • 221.
    Akillioglu, Hakan
    KTH, Skolan för industriell teknik och management (ITM), Industriell produktion, Produktionssystem.
    Evolvable Production Systems: Demand Responsive Planning2011Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Dynamic and unforeseeable characteristic of the current market and production environment is not feasible to be met through pre-set parameters being dependent on the predictions. Handling this matter requires to keep focus on production system adaptability. Evolvable Production System has achieved fully system reconfigurability through process oriented modularity and multi agent based distributed control system architecture. One of the essential enhancements provided by EPS on the shop floor is achieving minimized/eliminated system setup time in response to changing product requirements.

    Manufacturing planning and control system, on the other hand, follows hierarchical principles which are quite much reliant on the predicted information so to structure production and planning environment on it. Production system limitations, such as lack of adaptability in response to changing conditions, are in fact influencing the planning system to be structured on the predictions. The enhancements which are ensured by the architecture of EPS enable to relax the constraints on planning system which are imposed by the limitations of production system. These enhancements have an effect at different levels in the planning hierarchy. On the light of these improvements, the planning framework as it is used so far in the industry becomes invalid and this arise a requirement for planning system structure to be designed according to a fully reconfigurable system to be able to benefit such a production system by all means.

    This thesis targets to enlighten the relation between the production system characteristics and planning system structure by emphasizing the planning problems and proposing a planning reference architecture solution to be able achieve a responsive planning framework.

  • 222.
    Akillioglu, Hakan
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Industriell produktion, Produktionssystem.
    Dias-Ferreira, Joao
    KTH, Skolan för industriell teknik och management (ITM), Industriell produktion, Produktionssystem.
    Onori, Mauro
    KTH, Skolan för industriell teknik och management (ITM), Industriell produktion, Produktionssystem.
    Characterization of Continuous Precise Workload Control and Analysis of Idleness Penalty2014Ingår i: CIE 44 and IMSS14 proceedings, 2014, s. 1998-2011Konferensbidrag (Refereegranskat)
    Abstract [en]

    The variability in the market conditions is growing in terms of its frequency of change and range of diversity. In response to this new industrial panorama, research on production systems is aiming to achieve truly reconfigurable shop floors. Frequent changes in such systems require also frequent re-planning with updated information. In this regard the Continuous Precise Workload Control method, is a recent approach aiming at precise control of workload in the shop floor with the use of direct load graphs. Supported by a multi-agent platform, it generates dynamic non-periodic release decisions exploiting real time shop floor information. The study in this paper is two folded; (1) in order to highlight its distinctive characteristics, the presented workload approach is defined in terms of eight dimensions of the workload control concept and (2) the penalty of idleness which affects the decision of release is analyzed by an experiment design in order to investigate its correlation with two critical parameters, norm value and assessment range. The results show that the idleness penalty factor decreases the idleness of the resources up to a point where the adverse effect is initiated. Besides there are strong indications towards the correlation of idleness penalty factor with the norm value.

  • 223.
    Akillioglu, Hakan
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Industriell produktion, Produktionssystem.
    Ferreira, Joao
    KTH, Skolan för industriell teknik och management (ITM), Industriell produktion, Produktionssystem.
    Onori, Mauro
    KTH, Skolan för industriell teknik och management (ITM), Industriell produktion, Produktionssystem.
    Demand responsive planning: workload control implementation2013Ingår i: Assembly Automation, ISSN 0144-5154, E-ISSN 1758-4078, Vol. 33, nr 3, s. 247-259Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Purpose – Evolvable production systems enable fully reconfiguration capabilities on the shop floor through process-oriented modularity and multiagent-based distributed control. To be able to benefit architectural and operational characteristics of evolvable systems, there is a need of a newplanning approach which links shop floor characteristics and planning operations. This paper seeks to address these issues.

    Design/methodology/approach – Evolvable production system has a structured methodology in itself. Consistent to this, a reference planningarchitecture is developed aiming to achieve agility on planning activities. Besides a workload control method is proposed and implemented as a part ofthe planning architecture.

    Findings – First applications of evolvable systems have been implemented through European research projects. Shop floor working principles andarchitectural characteristics are consistent to facilitate more agility on planning activities which are framed at a planning reference architecture calleddemand responsive planning. As an implementation case, an agent-based workload control method is proposed and implemented. The characteristicsof EPS and proposed planning architecture enable continuous and dynamic workload control of the shop floor to be implemented.

    Originality/value – This paper presents a new planning model compatible with evolvable production systems targeting to agility to demand onplanning and control activities benefiting shop floor enhancements of a fully reconfigurable system which enables to relax constraints imposed fromproduction systems to planning. In addition, a continuous and dynamic workload control method is proposed and implemented.

  • 224.
    Akillioglu, Hakan
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Industriell produktion, Produktionssystem.
    Maffei, Antonio
    KTH, Skolan för industriell teknik och management (ITM), Industriell produktion, Produktionssystem.
    Neves, Pedro
    KTH, Skolan för industriell teknik och management (ITM), Industriell produktion, Produktionssystem.
    Ferreira, Joao
    KTH, Skolan för industriell teknik och management (ITM), Industriell produktion, Produktionssystem.
    Operational characterization of evolvable productionsystems2012Ingår i: 4th CIRP Conference on Assembly Technologies and Systems – CATS 2012, 2012, s. 85-90Konferensbidrag (Refereegranskat)
    Abstract [en]

    On the way to achieve mass customization production systems have to obtain the capability of rapid reconfiguration of not only physical components but also from control point of view. Evolvable Production System targets highly adaptable mechanical and control solutions that can enhance reusability and interoperability of modules, enabling lifetime extension of the modules. The focus of EPS paradigm is to achieve overall system adaptability by autonomous modules which are dedicated to specific processes with the capability of short deployment time at shop floor without reprogramming effort. From the operational point of view EPS brings significant enhancements considering shop floor dynamics and performances therefore positioning of EPS principles and approaches in production system typology from different perspectives is essential. This has been done by two means which are process flow structure and customer order decoupling point location.

  • 225.
    Akillioglu, Hakan
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Industriell produktion, Produktionssystem.
    Onori, Mauro
    KTH, Skolan för industriell teknik och management (ITM), Industriell produktion, Produktionssystem.
    Evolvable production systems and impacts on production planning2011Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Production planning and control strategies have been changing in line with the constant change on product and customer requirements, under the light of technological and scientific advancements. Production systems which are based on mass production became obsolete in time hence companies, being profit oriented, are in need of new solutions towards mass customization to handle rapidly changing market conditions. To deal with this issue, production systems and production planning strategies have to be complementing each other. In this paper Evolvable Production Systems and its compatibility to Just in Time (JIT) Production compared to Material Requirement Planning (MRP) will be discussed.

  • 226.
    Aktas, Stefanos
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Integrerad produktutveckling.
    Wennhall, Thomas
    KTH, Skolan för industriell teknik och management (ITM), Maskinkonstruktion (Inst.), Integrerad produktutveckling.
    AI - an Untapped Opportunity for Innovation Developing a Screening Tool for AI and Innovation2018Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Det är känt att innovation gör det möjligt för företag att tränga in på nya marknader och uppnå högre marginaler. Det är även känt att teknik kan bidra till att uppnå en konkurrensfördel och tillväxt för företag. En teknik som nyligen har vuxit till att bli relevant för företag är Artificiell Intelligens (AI). Trots det så har tidigare studier uttryckt svårigheten med att implementera AI, vilket motiverade denna studie.

    Huvudsyftet med denna studie var att utveckla och testa ett genomlysningsverktyg som kommer att fungera som ett stöd för att öka en organisations utnyttjande av AI och innovationsförmåga. Under studiens gång lades en stor del av fokuset också på att konstruera en preliminär analys i förberedning för en större studie som kommer att vara beroende av att samla stora mängder kvantitativ data.

    Forskningen utfördes genom en process uppdelad i tre faser. Den första fasen fokuserade på att få grundläggande kunskaper med avseende på AI, innovation, teknikhanterning och modellutveckling. Resultaten i den första fasen bidrog till att formulera lämpliga forskningsfrågor som var applicerbara för studien.

    Efter det så gick studien vidare till den andra fasen som fokuserade på en fördju-pad litteraturstudie. Detta ledde senare till utvecklingen av ett lämpligt frågefor-mulär som undersöker faktorer som är relevanta för både AI och innovation, och även en bedömningsmodell som är kopplad till frågeformuläret. Frågeformuläret användes för att samla svar som bidrog till den preliminära analysen i form av en pilotstudie. Frågeformuläret och bedömningsmodellen bildade tillsammans ett genomlysningsverktyg som ger en visuell redovisning av en organisations position med avseende på AI och innovation.

    Den tredje och sista fasen inkluderade tester av det skapade genomlysningsverktyget, analys av resultaten från pilotstudien och formuleringen av slutsatser gällande både genomlysningsverktyget och resultaten från pilotstudien.

    Resultatet från litteraturstudien var genomlysningsverktyget som tar hänsyn till fem dimensioner som anses vara relevanta för AI och innovation. Dessa dimensioner är Strukturer, Resurser, Metoder, Handling och Affärer,varavvarjeinnehållerområden som existerar i organisationen och kan anpassas för att förbättra AI-implementering och innovationshantering. Genomlysningsverktyget testades på två separata organ-isationer och lyckades reflektera dessa organisationers AI framsteg genom bedömn-ingsmodellen. Genomlysningsverktyget applicerades också på pilotstudien som re-sulterade i et antal indikationer av vad som kan förvätas i en större kvantitativ studie.

    Trots resultaten från denna studie visade det sig att ytterligare tester och studier måste göras för att uppnå mer pålitliga resultat. Denna studie kommer att fungera som riktlinje för framtida studier för att uppnå dessa resultat.

  • 227.
    Al Naami, Adam
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Energi och klimatstudier, ECS.
    Techno-economic Feasibility Study of a Biogas Plant for Treating Food Waste Collected from Households in Kartamantul Region, Yogyakarta2017Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Denna avhandling visar potentialen för biogasproduktion med hjälp av matavfall som samlats från regionen Kartamantul i Yogyakarta, Indonesien. Biogas kan användas för matlagning och elproduktion. Studien jämför två olika slutanvändningar eller marknader för att utnyttja biogasen i regionen. Det dagliga matavfallet som samlas i regionen Kartamantul är 120 ton. Detta motsvarar en daglig biogasproduktion på 13 087 m3. Elektricitet som genereras från biogas kan ersätta fossilbaserad koldioxid, medan tillagning av biogas kan ersätta det gemensamma fossila bränslet flytande petroleumgas (LPG). Priset för att sälja en kWh el till det statligt ägda företaget PLN är 16,5 USD cent. Priset för att sälja en m3 biogas för matlagning är 38,5 USD cent, vilket motsvarar det tillgängliga priset på LPG. Studien konstaterar att den undvikna utsläppet på grund av substitutionen av fossilbaserad kolkraft och matlagning av gasol är cirka 64 GgCO2-ekv per år.

    Med tanke på de ekonomiska resultaten för en livslängd på 20 år i det första utnyttjandegradet ger Biogas for Electricity ett nettopåverkande värde (NPV) på 2 MUSD medan för utnyttjandegraden Biogas for Cooking ger ett nettoförskott (NPV) på 5,82 MUSD. Breakeven för biogas för el är 13,8 USD cent per kWhe medan för Biogas for Cooking är 25,5 USD cent per m3-biogas. Studien drar slutsatsen att det är möjligt att investera i AD-anläggningar i regionen Kartamantul där båda marknaderna är lönsamma och miljövänliga. 

  • 228.
    Al Naami, Mahdi
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik.
    Thermal Conversion of MSW a Comparison of the System Performance: Direct Combustion Versus Conversion Through Syngas in CHP Plant2015Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [sv]

    Detta projekt är en studie som jämför två olika termiska omvandlingsvägar för kommunalt fast avfall (MSW). Jämförelsen kommer att inriktas på tekniska, ekonomiska aspekter. Den ena omvandlingsvägen är direkt förbränning av kommunalt avfall. Den andra omvandlingsvägen är att förvandla MSW till syntes gas som kommer att användas för produktion av värme och elektricitet. Den termiska omvandlingen händer i en Combined Heat and Power system (CHP-system) och från systemet undersöks de ekonomiska och tekniska aspekterna.

    CHP-förbränningsanläggning producerar el och värme från att massbränna MSW direkt utan sortering och CHP-förgasningsanläggning producerar el och värme från att förvandla MSW till syntes gas i en förgasare och sedan använda syntesgasen för att producera värme och el. För att få ett resultat av målet har följande frågor besvarats:

     

    • Vad är den övergripande ekonomiska prestationen i de två vägarna?
    • Vilka är skillnaderna i utsläpp beroende på termisk omvandlings väg?
    • Vad är den totala effektiviteten?

     

    Resultaten visar att det mest lönsamma termiska omvandlingsvägen är att direkt förbränna MSW i CHP-förbränning, eftersom det är en mer mogen teknik och därmed kostnaderna för att installera och när den är i drift är mycket mindre än att tillämpa det andra alternativet, men i de andra aspekterna är det motsatta. Vid förorening, är termisk omvandling av MSW till syntes gas för produktion av värme och kraft mycket mer miljövänligare och i fallet med den totala effektiviteten är den termiska omvandlingen av kommunalt avfall till syntes gas är högre och bättre.

  • 229.
    Al Shadidi, Kamilla
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    Oil Cooling of Electric Motor using CFD2014Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    This thesis investigated the heat transfer of internally oil cooled rotors in permanent magnet electric machines which are, among other things, used in hybrid vehicles or zero emission vehicles. The magnets become sensitive and can be demagnetized at high working temperatures, hence the need of cooling. The scope of this work included CFD simulations in STAR-CCM+. Three different 3D multiphase models simulating the oil propagation in the rotor were performed. A Lagrangian multiphase model combined with a fluid film model was the most suitable model for simulating the spray of the oil and the film thickness along the inner rotor wall. It was noticed that periodic boundaries caused problems for the fluid film model, therefore a complete geometry was preferred over a truncated model. The 3D solutions provided thicker film thicknesses than the analytical solutions from the fluid film thickness theory. The maximum analytical thickness was of the same order of magnitude as the surface average film thickness provided by the multiphase models. This thickness was assumed to be constant when used as the base for the fluid region in the 2D one-phase models.The study showed that aluminum was the most suitable rotor material due to its high conductive capacity, which provided a more even distribution of the temperature in the solid and hence resulted in lower overall temperatures. The cooling power increased linearly with the volumetric flow rate, however the heat transfer coefficient decreased for the higher flow rates. A volumetric flow rate of 10dl/min was recommended. A 2D model was compared to a preliminary experiment and showed that these were not correlated. The conclusion was that more experiments and simulations are needed in order to confirm the validity of the 2D model.

  • 230.
    Al Taweel, Maher
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Tillämpad termodynamik och kylteknik.
    CFD simulering av kallras: Undersökning av temperatur- och luftbeteende intill höga glasfasader och i vistelsezon med golvvärme som en värmekälla2013Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Glass has sophisticated front properties and are used as facades in high buildings. During cold periods, these glass facades could cause thermal discomfort, due to cold downdraught. Cold downdraught can be countered by placing heaters under glass surfaces. Nowadays technology offers highly insulating windows, which is why there is an interest to investigate the indoor climate with only underfloor heating. The research in this area is limited, and few empirical methods are available. Theoretical analysis has begun but it still brand new.

    The aim of this investigation was to present the thermal indoor climate influenced by various parameters, such as outdoor temperature, U-value and the glass height. The results were also meant to be used as reference tools in future projects. A reference building was modeled in simulation software called CFD Star-CCM+.

    The assignment was initiated by Incoord, a leading consulting company in energy, indoor climate and installation planning.

    The results showed that the air velocity increases with decreasing outdoor temperature and decreases with increasing thermal insulation (lower U-value). At the edges of the glass the air velocity becomes twice as large compared to the velocity of the air in the middle of the atrium. The air velocity (maximum and average) at 0.1 m above the floor is always higher than at 2.0 m. The lowest air velocities start from about 0.25 m/s at 0 ℃ and reaches to 0.60 m/s at -20 ℃. That means these air velocities are too high for what is accepted as a good indoor climate, where the maximum allowable air velocity is 0.15 m/s.

    The outdoor temperatures and the glass facade’s U-value also have an effect on the surface temperature of the glass facade. This decreases the surface temperature with decreased outdoor temperature, and the surface temperature increases at lower U-value.

    The height of the glass facades proved to affect both the air velocity in the occupied zone and in the glass surface temperature. The air velocity increases with the glass’ height. The increase is higher at 0.1 m than at 2.0 m above the floor.

    The result shows also that the average air velocity is lower than 0,15 m/s at window height lower than 5 m. But, at the same height the maximum air velocity is higher than 0.3 m/s. The surface temperature of the glass facades increases with the glass’ height. This is because the indoor heat transfer coefficient increases with height. The outdoor heat transfer coefficient is a function of the wind speed and was assumed to be constant.

    The underfloor heating, which is represented in the simulations with a floor surface temperature of 27 ℃, is not enough to maintain a good indoor climate in any of simulations.

    The results of this thesis showed a strong relation between indoor climate, outdoor temperature, U-value and the glass height. This study also showed that the floor heating is not enough to counteract the cold draft during extreme cold periods, in high glass buildings. The presented results can be used as a reference tool for the assessment of air velocities and surface temperatures, in similar high buildings.

  • 231.
    Alallak, Ali
    KTH, Skolan för industriell teknik och management (ITM), Industriell produktion, Maskin- och processteknologi.
    Deburring of components: A survey of current and future deburring processes2010Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The machining operations that shape a metal component produce a raised edge or small pieces of material remaining attached to a work piece called burrs and sharp edges. The deburring process is intended to remove these imperfections and produce specific edge profiles.

    Burr formation during machining operations is one of the most significant problems encountered by industrial companies in component manufacturing. Remaining burrs after machining pose a severe risk for component breakdowns, if the burrs get loose. All work piece edges must therefore be completely defect-free.

    In the machining industry manual methods are commonly employed for burr removal. Fully automating deburring operations present a major challenge. Furthermore, removal of internal burrs of various sizes and shapes from parts sometimes becomes an extremely difficult task which causes high cost for labor, time losses, and health and safety risks.

    Increasingly, manufacturers are expected to deliver burr-free parts to their customer. Sandvik Coromant, Scania and Volvo Cars are three of these manufacturers, and these three companies have agreed to contribute to this thesis.

    Sandvik Coromant AB is part of the global enterprise Sandvik Group AB, and is world- leading in providing and developing cutting tools for the metal working industry. The company operates in over 60 countries worldwide and its main production plant is located in Gimo, Sweden [www.sandvik.com].

    Scania is a global automotive industry manufacturer of commercial vehicles—specifically heavy trucks and buses. It also manufactures diesel engines for motive power of heavy vehicles, marine, and general industrial applications. Scania was founded in 1891 in Södertälje, Sweden. Today, Scania has ten production facilities worldwide [www.scania.com].

    Volvo Car Corporation is an automobile manufacturer founded in 1927, in Gothenburg, Sweden. Volvo Cars has approximately 2,300 local dealers and around 100 national sales companies worldwide. Volvo Car Engine is a part of Volvo Cars. Volvo Car Engine produces engines and other components for other units, and it is headquartered in Skövde, Sweden [www.volvocars.com].

    All of the companies above have problems in burr minimizing and removing strategy in machining and deburring operations to achieve quality assurance. Therefore, to choose a deburring system, and to reveal the results of deburring operations, it is necessary to be able to inspect/measure burrs. But, unfortunately, most industrial companies today lack the specialized systems to measure the presence of burrs, which adversely affect the overall deburring process. In this thesis, different types and sizes of work pieces have been taken directly from the production to measure burrs, and conduct experiments on them.

    The thesis focuses on three areas:

    • A survey of the current deburring problems, including burr classification and measurement, current minimization strategies of burr formation, and current deburring methods.
    • Experiments on new and improved deburring methods, including deburring tools (e.g. drilling deburring tools, countersink tools, grinding tools and alumina fiber brushes), water-jet deburring (multi-nozzle rotary lance jets, pure and abrasive single rotary nozzle water jets).
    • A selection matrix as a thesis conclusion which relates these methods to criteria of deburring processes, such as process performance, industrial applications, quality assurance, safety and environment, costs, etc. This matrix can be a basis for a more detailed selection/decision matrix in the future.
  • 232. Alam, M M
    et al.
    Barsoum, Zuheir
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Jonsen, P
    Kaplan, A F H
    Haggblad, H A
    Influence of defects on fatigue crack propagation in laser hybrid welded eccentric fillet joint2011Ingår i: Engineering Fracture Mechanics, ISSN 0013-7944, E-ISSN 1873-7315, Vol. 78, nr 10, s. 2246-2258Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Fatigue cracking of laser hybrid welded eccentric fillet joints has been studied for stainless steel. Two-dimensional linear elastic fracture mechanics analysis was carried out for this joint geometry for four point bending load. The numerical simulations explain for the experimental observations why the crack propagates from the lower weld toe and why the crack gradually bends towards the root. Lack of fusion turned out to be uncritical for the initiation of cracks due to its compressive stress conditions. The linear elastic fracture mechanics analysis has demonstrated in good qualitative agreement with fatigue test results that lack of fusion slightly (<10%) reduces the fatigue life by accelerating the crack propagation. For the geometrical conditions studied here improved understanding of the crack propagation was obtained and in turn illustrated. The elaborated design curves turned out to be above the standard recommendations.

  • 233. Alam, M. M.
    et al.
    Barsoum, Zuheir
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Jonsén, P.
    Kaplan, A. F. H.
    Häggblad, H. A.
    The influence of surface geometry and topography on the fatigue cracking behaviour of laser hybrid welded eccentric fillet joints2010Ingår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 256, nr 6, s. 1936-1945Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Laser hybrid welding of an eccentric fillet joint causes a complex geometry for fatigue load by 4-point bending. The weld surface geometry and topography were measured and studied in order to understand the crack initiation mechanisms. The crack initiation location and the crack propagation path were studied and compared to Finite Element stress analysis, taking into account the surface macro-and micro-geometry. It can be explained why the root and the upper weld toe are uncritical for cracking. The cracks that initiate from the weld bead show higher fatigue strength than the samples failing at the lower weld toe, as can be explained by a critical radius for the toe below which surface ripples instead determine the main stress raiser location for cracking. The location of maximum surface stress is related to a combination of throat depth, toe radius and sharp surface ripples along which the cracks preferably propagate.

  • 234. Alam, Minhaj M
    et al.
    Barsoum, Zuheir
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Jonsén, Pär
    Häggblad, Hans Åke
    Kaplan, Alexander
    Fatigue behaviour study of laser hybrid welded eccentric fillet joints – Part II: State-of-the-art of fracture mechanics and fatigue analysis of welded joints2009Ingår i: 12th NOLAMP proceeding 2009: Nordic Laser Materials Processing Conference / [ed] Erling Dam Mortensen, 2009Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Simplified fatigue and fracture mechanics based assessment methods are widely used by the industry to determine the structural integrity significance of postulated cracks, manufacturing flaws, service-induced cracking or suspected degradation of engineering components under normal and abnormal service loads. In many cases, welded joints are the regions most likely to contain original fabrication defects or cracks initiating and growing during service operation. The welded joints are a major component that is often blamed for causing a structure failure or for being the point at which fatigue or fracture problems initiate and propagate. Various mathematical models/techniques for various classes of welded joints are developed by analytically or by simulation software's that can be used in fatigue and fracture assessments. This literature survey compiled useful information on fracture and fatigue analysis of various welded joints. The present review is divided into two major sections- fracture mechanics and fatigue analysis with widely used models. A survey table is also introduced to get the outlook of research trend on fatigue and fracture over last 3 decades. Although tremendous research effort has been implemented on fatigue and fracture analysis of conventional welding, research on relatively new welding technology (laser welding, hybrid laser welding) is still limited and unsatisfactory. In order to give guarantee or make welding standard for new welding technology, further research is required in the field of fatigue and fracture mechanics including FEM and multi-scale modeling.

  • 235. Alam, Minhaj M
    et al.
    Barsoum, Zuheir
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Jonsén, Pär
    Häggblad, Hans Åke
    Kaplan, Alexander
    Geometrical Aspects of The Fatigue Behaviour of Laser Hybrid Fillet Welds2009Ingår i: Proceedings of the Fatigue Design Conference, 2009Konferensbidrag (Refereegranskat)
  • 236. Alam, Minhaj M
    et al.
    Barsoum, Zuheir
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, Lättkonstruktioner.
    Josén, Per
    Häggblad, Hans Åke
    kaplan, Alexander
    Fatigue Behaviour Study of Laser Hybrid Welded Eccentric Fillet Joints - Part I2009Ingår i: 12th NOLAMP proceeding 2009: Nordic Laser Materials Processing Conference / [ed] Erling Dam Mortensen, 2009Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Welded joints are a major component that is often responsible for causing a structure failure or for being the point at which fatigue cracking initiates and propagates. Despite tremendous research efforts, the understanding of fatigue behaviour is still limited, particularly for new techniques like laser hybrid welding. Beside a comprehensive state-of-the-art study, the paper presents a fatigue study of laser hybrid welded eccentric fillet joint of stainless steel of 10 mm thickness, with 5 mm displacement. Motivation is to study the influence of the surface geometry shape on fatigue performance under a four point bending test. 13 samples were produced, measuring the toe radii and testing under constant amplitude loading with stress ratio R=0. Different techniques have been used to measure local weld geometry, like plastic replica, a 3D optical profiler and a 3D-digitizer. The influence of the local weld geometry, like the toe radii, on the stress concentration was studied by FE-analysis. Occasionally lack of fusion was observed, which was taken into account in the FE-analysis. Based on the nominal stress approach, SN-curves were designed for laser hybrid welded eccentric fillet joints. Macro hardness tests were carried out and the crack surfaces were observed in order to detect crack initiation and propagation. Correlations between the toe radii, the corresponding stress maxima and crack initiation locations were studied between the different samples and even along the welds.

  • 237. Alameldin, A.
    et al.
    El-Gabry, L. A.
    Fridh, Jens
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Saha, Ranjan
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    CFD analysis of suction and pressure side film cooling influence on vane aero performance in a transonic annular cascade2014Ingår i: Proceedings of the ASME Turbo Expo, 2014Konferensbidrag (Refereegranskat)
    Abstract [en]

    Operating at temperatures well above their melting point, gas turbines' components are subject to terribly high thermal stresses. In order to keep them intact and performing, different cooling techniques are implemented. One of these methods is film cooling. Film cooling implementation in vane cascades has a potential loss expense. Proper assessment of its impact on the vane performance has to be conducted. The CFD approach of modeling each hole and cooling tube autonomously is very computationally expensive. In the current work an assessment of a new, more computationally efficient CFD approach for modelling film cooling was conducted on a vane cascade operating in the transonic regime (M =0.89). The film cooling holes were represented by orifice boundary condition at the vane surface, omitting the need to model internal coolant plenum and cooling tubes mesh, resulting in 180% reduction in grid size and attributed computational cost interpreted in 300% saving in computation time. Uncooled, and film cooled with different configurations and at different blowing ratios (BR) simulations were performed and compared to experimental measurements. A good agreement was obtained for the exit flow angles, vorticity and aerodynamic loss for all the cases (uncooled and cooled). Pitch-averaged exit flow angle outside endwalls regions remains unchanged for all cooling configurations and blowing ratios. The aerodynamic loss was found to be more sensitive to increasing the blowing ratio on the suction side than on the pressure side. The proposed approach of coolant injection modeling is shown to yield reliable results, within the uncertainty of the measurements in most cases. Along with lower computational cost compared to conventional film cooling modeling approach, the new approach is recommended for further analysis for aero and thermal vane cascade flows.

  • 238.
    Alaniz, Monica
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Mekanik, Strukturmekanik.
    Belyayev, Serhiy
    KTH, Skolan för teknikvetenskap (SCI), Mekanik, Strukturmekanik.
    Bergman, David
    Casselbrant, Gustav
    KTH, Skolan för teknikvetenskap (SCI), Mekanik, Strukturmekanik.
    Honeth, Mark
    KTH, Skolan för teknikvetenskap (SCI), Mekanik, Strukturmekanik.
    Huang, Jiangwei
    KTH, Skolan för teknikvetenskap (SCI), Mekanik, Strukturmekanik.
    Ivchenko, Nickolay
    KTH, Skolan för elektro- och systemteknik (EES), Rymd- och plasmafysik.
    Laukkanen, Mikko
    KTH, Skolan för teknikvetenskap (SCI), Mekanik, Strukturmekanik.
    Michelsen, Jacob
    KTH, Skolan för teknikvetenskap (SCI), Mekanik, Strukturmekanik.
    Pronenko, Vira
    KTH, Skolan för teknikvetenskap (SCI), Mekanik, Strukturmekanik.
    Paulson, Malin
    KTH, Skolan för teknikvetenskap (SCI), Mekanik, Strukturmekanik.
    Schlick, Georg
    KTH, Skolan för teknikvetenskap (SCI), Mekanik, Strukturmekanik.
    Tibert, Gunnar
    KTH, Skolan för teknikvetenskap (SCI), Mekanik, Strukturmekanik.
    Valle, Mario
    KTH, Skolan för teknikvetenskap (SCI), Mekanik, Strukturmekanik.
    The SQUID sounding rocket experiment2011Ingår i: Proceedings of the 20th ESA Symposium on European Rocket and Balloon Programmes and Related Research, European Space Agency, 2011, s. 159-166Konferensbidrag (Refereegranskat)
    Abstract [en]

    The objective of the SQUID project is to develop and in flight verify a miniature version of a wire boom deployment mechanism to be used for electric field measurements in the ionosphere. In February 2011 a small ejectable payload, built by a team of students from The Royal Institute of Technology (KTH), was launched from Esrange on-board the REXUS-10 sounding rocket. The payload separated from the rocket, deployed and retracted the wire booms, landed with a parachute and was subsequently recovered. Here the design of the experiment and post fight analysis are presented.

  • 239.
    Alanne, Kari
    et al.
    Department of Energy Technology, Aalto University.
    Kari, Saari
    Department of Energy Technology, Aalto University.
    Mannu, Kuosa
    Department of Energy Technology, Aalto University.
    Md., Rahman
    Department of Energy Technology, Aalto University.
    Martin, Andrew
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Microgeneration and Desalination Using Rotary Steam Engine (RTE) Technology2011Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper discusses the conditions to develop a micro-cogeneration plant based on biomass-fuelled rotary steam engine (RSE). The use of RSE in micro-cogeneration is justifiable due to relatively high electrical efficiency, capability of applying versatile thermal sources and low operational temperatures and pressures. At steam temperatures 200…300ºC, the electrical efficiency of 20 % may be obtained with the electrical power varying between 1…20 kWe. The other advantages of an RSE are that it is lubricant free and the noise level is low. In residential applications, an RSE may be considered an alternative for Stirling Engines and internal combustion engines, when integrated into a hydronic heating system and electrical grid. Another promising adaptation is desalination. A solar-powered RSE micro-cogeneration system would provide an inexpensive option to supply fresh water and electricity for the rural areas in developing countries that have access to sea water. A 10 kWe RSE plant combined with a once-through multi-stage flash (MSF) distillation plant is estimated to have potential of producing pure water from 180 to 800 kg/h.

  • 240.
    Alanne, Kari
    et al.
    Department of Energy Technology, Aalto University.
    Saari, Kari
    Department of Energy Technology, Aalto University.
    Jokisalo, Juha
    Department of Energy Technology, Aalto University.
    Martin, Andrew R.
    KTH, Skolan för industriell teknik och management (ITM), Energiteknik, Kraft- och värmeteknologi.
    Thermo-economic analysis of a micro-cogeneration system based on a rotary steam engine (RSE)2012Ingår i: Applied Thermal Engineering, ISSN 1359-4311, E-ISSN 1873-5606, Vol. 44, s. 11-20Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A rotary steam engine (RSE) is a simple, small, quiet and lubricant-free option for micro-cogeneration. It is capable of exploiting versatile thermal sources and steam temperatures of 150 to 180 ºC, which allow operational pressures less than 10 bar for electrical power ranges of 1 to 20 kWe. An RSE can be easily integrated in commercially available biomass-fired household boilers. In this paper, we characterize the boiler-integrated RSE micro-cogeneration system and specify a two-control-volume thermodynamic model to conduct performance analyses in residential applications. Our computational analysis suggests that an RSE integrated with a 17 kWth pellet-fuelled boiler can obtain an electrical output of 1.925 kWe, in the design temperature of 150 ºC, the electrical efficiency being 9% (LHV) and the thermal efficiency 77% (LHV). In a single-family house inFinland, the above system would operate up to 1274 h/a, meeting 31% of the house’s electrical demand. The amount of electricity delivered into the grid is 989 kWh/a. An economic analysis suggests that incremental costs not exceeding € 1,500 are justifiable at payback periods less than five years, when compared to standard boilers.

  • 241.
    Alazar, Abebayehu Seifu
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Industriell produktion.
    Werner, Mathias
    KTH, Skolan för industriell teknik och management (ITM), Industriell produktion, Maskin- och processteknologi.
    Nicolescu, Cornel Mihai
    KTH, Skolan för industriell teknik och management (ITM), Industriell produktion.
    Development of cutting force measurement system used in gear hobbing2011Ingår i: Proceedings Of The ASME International Design Engineering Technical Conferences And Computers And Information In Engineering Conference, 2011, Vol 8, ASME Press, 2011, s. 47-52Konferensbidrag (Refereegranskat)
    Abstract [en]

    Increasing demands for high quality and high performance gear manufacturing are reflected in a need for a model based investigation of gear hobbing process. This paper presents the development of a system for online measurement of actual cutting force components during gear hobbing. Although there are a large number of well developed cutting force measuring systems for different machining operations available in the market, it is difficult to find a system tailored to the requirements of a gear hobbing process. Hence, a fixture containing piezoelectric dynamometer and telemetry device is developed. The fixture is designed taking the real machining circumstances into consideration. The telemetry system enables wireless measurement of cutting force while machining. Multiphysics finite element analysis and Artificial Neural Network (ANN) are used as tools for modeling, simulation, and calibration of the developed system. Final stage of this work includes conducting hobbing experiments to validate both the model and the force measurement system.

  • 242. Alberdi, A.
    et al.
    Gil-Negrete, N.
    Vinolas, J.
    Kari, Leif
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg.
    Nieto, F. J.
    Dynamic characterisation of different magneto-sensitive natural rubbers for application in vibration isolation2010Ingår i: Proceedings of ISMA 2010 - International Conference on Noise and Vibration Engineering, including USD 2010, Katholieke Universiteit Leuven , 2010, s. 227-231Konferensbidrag (Refereegranskat)
    Abstract [en]

    Dynamic properties of magneto-sensitive natural rubber components were experimentally studied. Different magneto-sensitive rubbers were manufactured, consisting of irregularly shaped micron-sized iron particles embedded in a natural rubber matrix, and the influence of the hardness of the matrix material and the particle volume concentration were analyzed. Vibration isolators consisting of magneto-sensitive elastomers promise to have more functionality than conventional isolators as they can change their dynamic stiffness rapidly, continuously and reversibly under the application of an external magnetic field. Experimental measurements on MS components show that a better performance may be obtained at applications where small amplitudes are required, using soft matrix materials and with concentration close to a critical particle volume fraction.

  • 243.
    Alberdi-Muniain, Ane
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Strukturakustik.
    Magneto-sensitive elastomers in vibration isolation2012Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Vibration isolators made of rubber are used in numerous engineeringapplications to isolate structures from undesirable effects of vibrations.However, once a vibration isolator is installed in an application, it is not possible to modify its characteristics to adjust to changing conditions. An alternative to obtain more adaptive characteristics is touse magneto-sensitive (MS) elastomers. MS elastomers are a type of smart material consisting of an elastomer matrix, such as natural or synthetic rubber, to which iron particles are added displaying properties that vary rapidly, continuously and reversibly by applying an external magnetic field.The aim of this thesis is to investigate the possibility to use MS natural rubber in vibration isolation.Firstly, dynamic shear properties of MS natural rubber are experimentally studied at various frequencies, dynamic amplitudes and magnetic fields. In addition, the influence on the dynamic properties of adding carbon black and plasticisers to MS rubber is investigated. Carbon black is the most popular reinforcing filler that rubber usually contains in engineering applications to improve mechanical properties where as plasticisers simplify the filler blending process.Furthermore, the effectiveness of MS rubber applied in a vibration isolation system is experimentally investigated by measuring the energy flow into the foundation. The energy flow, including both force and velocity of the foundation, is a suitable measure of the effectiveness of a real vibration isolation system where the foundation is not perfectly rigid. The vibration isolation system in this study consists of a solid aluminium mass excitedby an electro-dynamic shaker and mounted upon four nonlinear frequency,amplitude and magnetic field dependent MS isolators being connected to a relatively stiff foundation. The energy flow through the MS isolators is directly measured by inserting a force transducer below each isolator andan accelerometer on the foundation close to each isolator. MS isolators are shown to be more useful than conventional rubber isolators since the dynamic stiffness varies with the application of an external magnetic field,thus resulting in more effective vibration isolation. In addition, the indirect technique is employed to measure the energy flow while requiring only accelerometers since it is usually difficult to directly measure the force in a real application. The indirect technique is validated by direct measurements.Finally, a model of the energy flow through the nonlinear frequency,amplitude and magnetic field dependent MS isolators is developed for the tested vibration isolation system. Vibration isolators are usually only a small connecting component within a more complex system. Hence, simple discrete models are frequently used to characterise the frequency and dynamic amplitude dependence of rubber. Recently, a model of this type has been modified to include magneto-sensitivity and thus model MS rubber. In this study, this novel MS rubber model is incorporated into the full system to model the MS isolators while the foundation is characterised by its driving-point and transfer inertances at and between the connection points.The energy flow model results are compared to those of measurements,showing good agreement. The developed energy flow model provides a basis to design vibration isolator systems made of MS isolators.

  • 244.
    Alberdi-Muniain, Ane
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Strukturakustik.
    Gil-Negrete, N.
    Department of Applied Mechanics, CEIT and Tecnun (University of Navarra).
    Kari, Leif
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Strukturakustik.
    Direct energy flow measurement in magneto-sensitive vibration isolator systems2012Ingår i: Journal of Sound and Vibration, ISSN 0022-460X, E-ISSN 1095-8568, Vol. 331, nr 9, s. 1994-2006Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The effectiveness of highly nonlinear, frequency, amplitude and magnetic field dependent magneto-sensitive natural rubber components applied in a vibration isolation system is experimentally investigated by measuring the energy flow into the foundation. The energy flow, including both force and velocity of the foundation, is a suitable measure of the effectiveness of a real vibration isolation system where the foundation is not perfectly rigid. The vibration isolation system in this study consists of a solid aluminium mass supported on four magneto-sensitive rubber components and is excited by an electro-dynamic shaker while applying various excitation signals, amplitudes and positions in the frequency range of 20-200 Hz and using magneto-sensitive components at zero-field and at magnetic saturation. The energy flow through the magneto-sensitive rubber isolators is directly measured by inserting a force transducer below each isolator and an accelerometer on the foundation close to each isolator. This investigation provides novel practical insights into the potential of using magneto-sensitive material isolators in noise and vibration control, including their advantages compared to traditional vibration isolators. Finally, nonlinear features of magneto-sensitive components are experimentally verified.

  • 245.
    Alberdi-Muniain, Ane
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Strukturakustik.
    Gil-Negrete, N
    Kari, Leif
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Strukturakustik.
    Indirect energy flow measurement in magneto-sensitive vibration isolator systems2013Ingår i: Applied Acoustics, ISSN 0003-682x, ISSN 0003-682x, Vol. 74, nr 4, s. 575-584Artikel i tidskrift (Övrigt vetenskapligt)
    Abstract [en]

    The indirect energy flow measurement method is extended to cover highly nonlinear, frequency, amplitude and magnetic field dependent magneto-sensitive natural rubber isolators applied in a real vibration isolation system. Energy flow is an effective measure of vibration isolation while being a single quantity that considers both force and velocity. The use of the indirect technique is of interest while requiring only accelerometers since it is usually difficult to directly measure the force in a real application. The vibration isolation system is composed of four magneto-sensitive rubber isolators that are inserted under a vibrating source consisting of a solid aluminium mass excited by an electro-dynamic shaker. Magneto-sensitive rubber isolators are more useful than conventional rubber isolators since the dynamic stiffness varies with the application of an external magnetic field, thus resulting in more effective vibration isolation. Various approximations regarding the indirect technique are investigated, concluding that average stiffness of magneto-sensitive isolators can be used and auto-spectrum of the foundation velocity ignored. In addition, various error analyses are performed. Finally, the indirect measurement of the energy flow is validated by direct measurements, showing very good agreement.

  • 246.
    Alberdi-Muniain, Ane
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Strukturakustik.
    Gil-Negrete, N
    Kari, Leif
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Strukturakustik.
    Modelling energy flow through magneto-sensitive vibration isolators2013Ingår i: International Journal of Engineering Science, ISSN 0020-7225, E-ISSN 1879-2197, Vol. 65, s. 22-39Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A highly nonlinear model of the energy flow in a magneto-sensitive (MS) vibration isolation system is developed where it is possible to investigate the influences of MS rubber material parameters; magnetic field strength; MS isolator dimension and position; excitation force magnitude, position and frequency; engine mass, inertia and dimension and, finally, foundation inertance. The MS vibration isolation system consists of an engine modelled by a solid mass, excited by a vertical force and mounted upon four MS isolators being connected to a relatively stiff foundation characterised by its driving-point and transfer inertances at and between the connection points. The energy flow into the foundation is the most appropriate indicator of the effectiveness of a real vibration isolation system while considering both foundation velocity and force. The MS isolator model applied is a nonlinear MS rubber model including frequency, dynamic amplitude and magnetic field dependence. The energy flow model results are compared to those of measurements, showing good agreement. Finally, parameter studies are carried out. The developed energy flow model provides a basis for designing MS vibration isolation systems to meet specific requirements.

  • 247.
    Alberdi-Muniain, Ane
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Strukturakustik.
    Gil-Negrete, N.
    Department of Applied Mechanics, CEIT and Tecnun (University of Navarra).
    Nieto, F.J.
    Department of Applied Mechanics, CEIT and Tecnun (University of Navarra).
    Kari, Leif
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Strukturakustik.
    Vinolas, J.
    Department of Applied Mechanics, CEIT and Tecnun (University of Navarra).
    An experimental study of magneto-sensitive natural rubber components applied in a vibration isolation system2009Ingår i: CONSTITUTIVE MODELS FOR RUBBER VI / [ed] Gert Heinrich, Michael Kaliske, Alexander Lion, London: Taylor & Francis, 2009, s. 99-104Konferensbidrag (Refereegranskat)
    Abstract [en]

    The effectiveness of magneto-sensitive natural rubber components applied in a vibration isolation system is experimentally investigated, where influences of excitation position, amplitude, frequency and magnetic field are examined. The magneto-sensitive elastomer consists of micron-sized, irregularly shaped iron particles blended in soft natural rubber at a concentration close to the critical particle volume fraction, shown to be the most favorable composition for optimum behaviour. A rigid aluminium mass supported on four vibration isolators is excited by an electro-dynamic shaker. Each component of this vibration isolation system is composed of two thin, square shaped, symmetrically positioned magneto-sensitive elements excited in simple shear with a magnetic field applied perpendicularly to the motion by an electromagnet. The magnetic field is varied by applying different intensities through the coil. The excitation position is either on the centre or on the edge of the surface of the mass, using step-sine excitation of various amplitudes in the frequency range of 0 to 300 Hz. The results show that it is possible to use magneto-sensitive rubber for vibration control purposes.

  • 248.
    Alberer, Daniel
    et al.
    Johannes Kepler University.
    Hjalmarsson, HåkanKTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.del Re, LuigiJohannes Kepler University.
    Identification for Automotive Systems2012Samlingsverk (redaktörskap) (Refereegranskat)
  • 249.
    Alberer, Daniel
    et al.
    Johannes Kepler University.
    Hjalmarsson, Håkan
    KTH, Skolan för elektro- och systemteknik (EES), Reglerteknik. KTH, Skolan för elektro- och systemteknik (EES), Centra, ACCESS Linnaeus Centre.
    del Re, Luigi
    Johannes Kepler University.
    System Identification for Automotive Systems: Opportunities and Challenges2012Ingår i: Identification for Automotive Systems / [ed] Daniel Alberer, Håkan Hjalmarsson, Luigi del Re, Springer London, 2012, s. 1-10Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    Without control many essential targets of the automotive industry could not be achieved. As control relies directly or indirectly on models and model quality directly influences the control performance, especially in feedforward structures as widely used in the automotive world, good models are needed. Good first principle models would be the first choice, and their determination is frequently difficult or even impossible. Against this background methods and tools developed by the system identification community could be used to obtain fast and reliably models, but a large gap seems to exist: neither these methods are sufficiently well known in the automotive community, nor enough attention is paid by the system identification community to the needs of the automotive industry. This introduction summarizes the state of the art and highlights possible critical issues for a future cooperation as they arose from an ACCM Workshop on Identification for Automotive Systems recently held in Linz, Austria.

  • 250.
    Albernaz, Daniel
    KTH, Skolan för teknikvetenskap (SCI), Mekanik, Fysiokemisk strömningsmekanik.
    Phase change, surface tension and turbulence in real fluids2016Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Sprays are extensively used in industry, especially for fuels in internal combustion and gas turbine engines. An optimal fuel/air mixture prior to combustion is desired for these applications, leading to greater efficiency and minimal levels of emissions. The optimization depends on details regarding the different breakups, evaporation and mixing processes. Besides, one should take into consideration that these different steps depend on physical properties of the gas and fuel, such as density, viscosity, heat conductivity and surface tension.

    In this thesis the phase change and surface tension of a droplet for different flow conditions are studied by means of numerical simulations.This work is part of a larger effort aiming to developing models for sprays in turbulent flows. We are especially interested in the atomization regime, where the liquid breakup causes the formation of droplet sizes much smaller than the jet diameter. The behavior of these small droplets is important to shed more light on how to achieve the homogeneity of the gas-fuel mixture as well as that it directly contributes to the development of large-eddy simulation (LES) models.

    The numerical approach is a challenging process as one must take into account the transport of heat, mass and momentum for a multiphase flow. We choose a lattice Boltzmann method (LBM) due to its convenient mesoscopic natureto simulate interfacial flows. A non-ideal equation of state is used to control the phase change according to local thermodynamic properties. We analyze the droplet and surrounding vapor for a hydrocarbon fuel close to the critical point. Under forced convection, the droplet evaporation rate is seen to depend on the vapor temperatureand Reynolds number, where oscillatory flows can be observed. Marangoni forces are also present and drivethe droplet internal circulation once the temperature difference at the droplet surface becomes significant.In isotropic turbulence, the vapor phase shows increasing fluctuations of the thermodynamic variables oncethe fluid approaches the critical point. The droplet dynamics is also investigated under turbulent conditions, where the presence of coherent structures with strong shear layers affects the mass transfer between the liquid-vapor flow, showing also a correlation with the droplet deformation. Here, the surface tension and droplet size play a major role and are analyzed in detail.

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