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  • 201.
    Ahmed, Sunny
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Olsson, Linnéa
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Urbanears Ugglan - Studying Usercentered Designin Product Development2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This report describes the master’s thesis conducted by Sunny Ahmed and Linnéa Olssonat KTH Royal Institute of Technology for the client Zound Industries. By exploringemerging technologies and user needs, the project members developed a design proposal forheadphones for active users that can be released in three to five years’ time.Urbanears Ugglan is the headphone solution that allows you to take control of your physicalactivities and experience true freedom. It consists of two parts: true wireless earphonesand a wearable wrist accessory that stores and charges the earphones on the go, while alsofunctioning as a fitness tracker.Aside from the first purpose of creating the design proposal, the second purpose of the thesiswas to investigate the impact of involving the intended user in the design process duringproduct development when adopting a user-centered design approach.Different methods were used to gather relevant information. Both market research and atechnical trend analysis were done as background research, and complemented the userstudies. The insights discovered from these phases were used to generate concepts, fromwhich one was selected for further development after discussion with the client company. Thisconcept evolved into the final design proposal, Urbanears Ugglan.The project team found a positive impact from using user-centered design and involving theuser in several stages of the project. Including the intended user in the development led toa better understanding of their needs and values, which in turn allowed the project team toquickly verify the potential of product ideas.

  • 202.
    Ahola, A.
    et al.
    Lappeenranta Lahti Univ Technol LUT, Sch Energy Syst, POB 20, FI-53851 Lappeenranta, Finland..
    Bjork, T.
    Lappeenranta Lahti Univ Technol LUT, Sch Energy Syst, POB 20, FI-53851 Lappeenranta, Finland..
    Barsoum, Zuheir
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Fatigue strength capacity of load-carrying fillet welds on ultra-high-strength steel plates subjected to out-of-plane bending2019In: Engineering structures, ISSN 0141-0296, E-ISSN 1873-7323, Vol. 196, article id UNSP 109282Article in journal (Refereed)
    Abstract [en]

    Weld root fatigue strength capacity is an important design criterion in load-carrying (LC) fillet welded joints subjected to cyclic loads. This paper elaborates on the weld root fatigue strength capacity of fillet welded LC joints made of ultra-high-strength steel (UHSS) and subjected to out-of-plane bending. Experimental fatigue tests are carried out using constant amplitude loading with an applied stress ratio of R = 0.1 with both pure axial, i.e. DOB = 0 (degree of bending, bending stress divided by total stress) and bending, i.e. DOB = 1.0, load conditions. The applicability of different approaches - nominal weld stress, effective notch stress concepts, and 2D linear elastic fracture mechanics (LEFM) - for the fatigue strength assessment of weld root capacity is evaluated. Furthermore, a parametric LEFM analysis is used to evaluate the effect of weld penetration on the root fatigue strength capacity in axial and bending loading. The results indicate that in the case of bending, nominal weld stress can be calculated using the linear stress distribution over the joint section and FAT36 as a reference curve. In the bending loading, for the joints failing from the weld toe, a mean fatigue strength of up to 185 MPa in the nominal stress system was achieved, indicating that the reference curve FAT63 is overly conservative. The ENS concept with FAT225 seemed to be slightly unconservative for assessing the root fatigue strength capacity. LEFM analyses revealed that in the case of increasing weld penetration and bending loading, weld root fatigue strength capacity seemed to correlate with the nominal weld stress calculated using effective weld throat thickness, while in axial loading, weld stress should be calculated using external throat thickness summed with penetration length.

  • 203.
    Aichmayer, Lukas
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Solar Receiver Design and Verification for Small Scale Polygeneration Unit2011Independent thesis Advanced level (degree of Master (Two Years)), 30 credits / 45 HE creditsStudent thesis
    Abstract [en]

    Against a backdrop of our world’s changing climate solar thermal power generation shows great potential to move global energy production away from fossil fuels to non-polluting sources. The Department of Energy Technology at the Royal Institute of Technology Stockholm is contributing to the development and research of solar thermal power by building a solar driven small scale polygeneration unit based on an externally fired micro gas turbine.

    This project focused on the design, analysis and verification of a high temperature solar receiver for integration into this planned solar polygeneration unit. Mean irradiance levels at the focal spot of the solar receiver of 5.5 MW/m² and peak levels of 14 MW/m² were identified as major design challenges. A preliminary heat transfer analysis found volumetric receivers to be the only applicable receiver type capable of withstanding these expected high irradiance levels.

    With volumetric receivers selected as the receiver type, a basic volumetric receiver model was evaluated using a multi-objective optimization tool based on advanced evolutionist algorithms and a numerical heat transfer model. The results were a set of Pareto-optimal solutions showing a tradeoff between a pressure drop in the receiver and material temperature especially at the window of the receiver.

    A parameter study was conducted based on the previous analysis to improve specific aspects of the initial design using a value of benefit analysis to evaluate the different designs. Of all the investigated receiver parameters, the absorber properties and shape had the biggest positive influence on material temperature and thermal stresses without significantly increasing the pressure drop. External cooling of the receiver window with ambient air was found to beneficial influence the window temperature without greatly decreasing the thermal efficiency. For non-uniform high irradiance levels ceramic absorber materials were found to be most suitable. Furthermore, mechanically decoupling the window and the absorber from their surrounding parts was found to be very important; enabling them to expand more or less independently with changing temperature minimizing thermal stresses.

    It can be concluded, when properly designed, volumetric solar receivers for small scale solar polygeneration units are feasible as designs with material temperature, thermal stresses and pressure drop below acceptable limit were found within this work.

  • 204.
    Aichmayer, Lukas
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Solar receiver development for gas-turbine based solar dish systems2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Small-scale concentrating solar power plants such as micro gas-turbine based solar dish systems have the potential to harness solar energy in an effective way and supply electricity to customers in remote areas. In such systems, the solar receiver transfers the power of concentrated solar radiation to the working fluid of the power conversion cycle. It is one of the key components as it needs to operate at high temperatures to ensure a high power cycle efficiency and under high flux densities to ensure a high receiver efficiency. In order to address these challenges and to ensure efficient and reliable operation innovative designs are needed.

    This research work focuses on the complete development of a novel solar receiver applying a new systematic design and analysis methodology. Therefore, a comprehensive receiver design and experimental evaluation process were developed and implemented. The design process includes the identification of technical specifications and requirements, the development of receiver design tools of different investigation levels coupled with multi-objective optimization tools, the evaluation of scaling effects between tests in the KTH high-flux solar simulator and the full-scale solar dish system. As a result of the design process a representative final receiver was established with material temperatures and stresses below critical limits while respecting the design specification.

    The experimental evaluation includes the enhancement of the KTH high-flux solar simulator to provide stable and reliable operating conditions, the precise characterization of the radiative boundary conditions, the design of a receiver test bed recreating the operating behavior of a gas-turbine, and the final receiver testing for multiple operating points. It was shown that the prototype reaches an efficiency of 69.3% for an air outlet temperature of 800°C and a mass flow of 29.5 g/s. For a larger mass flow of 38.4 g/s a receiver efficiency of 84.8% was achieved with an air outlet temperature of 749°C.

    The measurement results obtained were then used for a multi-point validation of the receiver design tools, resulting in a high level of confidence in the accuracy of the tools. The validated models were then harnessed to calculate the performance of a full-scale solar receiver integrated into the OMSoP solar dish system. It was shown that a solar receiver can be designed, which delivers air at 800°C with a receiver efficiency of 82.2%.

    Finally, the economic potential of micro gas-turbine based solar systems was investigated and it was shown that they are ideally suited for small-scale stand-alone and off-grid applications.

    The results of the receiver development highlight the feasibility of using volumetric solar receivers to provide heat input to micro gas-turbine based solar dish systems and no major hurdles were found.

  • 205.
    Aichmayer, Lukas
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Garrido, Jorge
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Performance Improvements of the KTH High-Flux Solar Simulator2017In: AIP Conference Proceedings 1850, American Institute of Physics (AIP), 2017, Vol. 1850, article id 150001Conference paper (Refereed)
    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.

  • 206.
    Aichmayer, Lukas
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Garrido, Jorge
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Scaling effects of a novel solar receiver for a micro gas-turbine based solar dish system2018In: International Journal of Solar Energy, ISSN 0142-5919, E-ISSN 1477-2752, Vol. 162, p. 248-264Article in journal (Refereed)
    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.

  • 207.
    Aichmayer, Lukas
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Spelling, James
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Preliminary design and analysis of a novel solar receiver for a micro gas-turbine based solar dish system2015In: Solar Energy, ISSN 0038-092X, E-ISSN 1471-1257, Vol. 114, no 4, p. 378-396Article in journal (Refereed)
    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.

  • 208.
    Aichmayer, Lukas
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Spelling, James
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Small Scale Hybrid Solar Power Plants for Polygeneration in Rural Areas2014In: Energy Procedia 57, Elsevier, 2014, Vol. 57, p. 1536-1545Conference paper (Refereed)
    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.

  • 209.
    Aichmayer, Lukas
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Spelling, James
    IMDEA Energy Institute, Spain.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Thermoeconomic Analysis of a Solar Dish Micro Gas-Turbine Combined-Cycle Power Plant2015In: Energy Procedia 69, Elsevier, 2015, Vol. 69, p. 1089-1099Conference paper (Refereed)
    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.

  • 210.
    Aichmayer, Lukas
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Spelling, James
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fransson, Torsten
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Micro Gas-Turbine Design for Small-Scale Hybrid Solar Power Plants2013In: Proceedings of the ASME Turbo Expo 2013. San Antonio, USA. June 3-7, ASME , 2013Conference paper (Refereed)
    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%.

  • 211.
    Aichmayer, Lukas
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Spelling, James
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Fransson, Torsten
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Micro Gas-Turbine Design for Small-Scale Hybrid Solar Power Plants2013In: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 135, no 11, p. 113001-Article in journal (Refereed)
    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%.

  • 212.
    Aichmayer, Lukas
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Spelling, James
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Wang, Wujun
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Design and Analysis of a Solar Receiver for Micro Gas Turbine based Solar Dish Systems2012In: Proceedings of the International SolarPACES Conference 2012. Marrakesh, Morocco. September 11-14, 2012, 2012Conference paper (Refereed)
    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.

  • 213.
    Aichmayer, Lukas
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Wang, Wujun
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Garrido, Jorge
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Experimental evaluation of a novel solar receiver for a micro gas-turbine based solar dish system in the KTH high-flux solar simulator2018In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 159, p. 184-195Article in journal (Refereed)
    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.

  • 214.
    Aichmayer, Lukas
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Wang, Wujun
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Garrido, Jorge
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Laumert, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Experimental Flux Measurement of a High-Flux Solar Simulator using a Lambertian Target and a Thermopile Flux Sensor2016In: AIP Conference Proceedings 1734, American Institute of Physics (AIP), 2016, Vol. 1734, article id 130001Conference paper (Refereed)
    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.

  • 215.
    AIDANPÄÄ, MATHILDA
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Integrated Product Development.
    SJÖBERG, MATHILDA
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Integrated Product Development.
    De etiska konsekvenserna av produktutveckling: Oönskade konsekvenser av strävan efter zero-labourfactories2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Today’s development of automation happens at an increasing rate driven by innovation and product development. Companies have to keep up with this progress to stay competitive. The question has risen whether we are now facing a new industrial revolution or not. The ethical perspective has now become a concern.

    The purpose of this report is to investigate the following questions:

    • How big of a role has the ethical perspective in decision-making processes with regards to automation?

    • Who is responsible for ethical issues within product development?

    • To what extent should ethics be a part of engineering education?

    The chosen method during the study was extensive literature studies and semi structured interviews with employees and managers from the affected area.

    The result of the report is that the ethical perspective has a smaller impact in the decisionmaking processes compared to other factors. The responsibility of the ethical consequences lies in both product development companies and producing companies. Finally, ethical perspectives should be integrated into engineering education.

  • 216.
    Aidanpää, Sandra
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Nordmark, Elin MK
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Flexible Updates of Embedded Systems Using Containers2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this thesis the operating-system-level virtualization solution Docker is investigated in the context of updating an embedded system on application level. An updating sequence is designed, modelled and implemented, on which experiments are conducted to measure uptime and current. Within the popular notion of the Internet of Things, more and more things are being connected to the Internet and there by the possibility of dynamic updates over the Internet is created. Being able to update remotely can be very benecial, as systems may be costly or unpractical to reach physically for software updates. Operating-system-level virtualization, software containers, are a lightweight virtualization solution that can be used for dynamic updating purposes. Virtualization properties, like resource isolation and letting software share hardware capabilities are used in determining the architecture. The container architecture used is a microservice architecture, where systems are composed from many smaller, loosely coupled services. The application area for the results of this thesis are start-ups in the Internet of Things eld, delimited to low complexity systems such as consumer products. The update regime is created with the properties of microservice architectures in mind, creating a self-propelling, self-testing, scalable and seamless dynamic updating process that can be used for systems of dierent complexity. The update regime is modeled to give proof of concept and to help design the implementation. The implemented update regime was made on an ARM based single board computer with a Linux-kernel based operating system running Docker. Experiments were then conducted in order to give a clear indication of the behavior of a dynamically updated embedded system. The experiments showed that the update regime can be seamless, meaning that the uptime properties are not aected by this kind of updating. The experiments also showed that no signicant changes in current can be noted for container limitations during this kind of update.

  • 217.
    Aishwar, Ravichandran
    KTH, School of Engineering Sciences (SCI).
    Aerodynamics of Bird Flight2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    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.

  • 218.
    Ajmal Khan, Muhammad
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Raza, Rizwan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Bohn Lima, Raquel
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology. KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    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)2013In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 38, no 36, p. 16524-16531Article in journal (Refereed)
    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.

  • 219.
    Akander, Jan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Alvarez, S
    Jóhannesson, Gundi
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Energy normalization techniques2004In: Energy Performance of Residential Buildings: A Practical Guide for Energy Rating and Efficiency, James & James/Earthscan , 2004, p. 57-70Chapter in book (Other academic)
  • 220.
    Akander, Jan
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Jóhnnesson, Gudini
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering.
    Experimental methods for the energy characterization of buildings2004In: Energy Performance of Residential Buildings: A Practical Guide for Energy Rating and Efficiency, James & James/Earthscan , 2004, p. 26-56Chapter in book (Other academic)
  • 221.
    Akbarpour, S.
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Hallström, S.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Metal reinforcement around fastener holes in composites2016In: ECCM 2016 - Proceeding of the 17th European Conference on Composite Materials, European Conference on Composite Materials, ECCM , 2016Conference paper (Refereed)
    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.

  • 222.
    Akhlaghi, Shahin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials. Scania CV AB, Sweden.
    Gedde, Ulf W.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Hedenqvist, Mikael S.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Brana, Maria T. Conde
    Bellander, Martin
    Deterioration of automotive rubbers in liquid biofuels: A review2015In: Renewable & sustainable energy reviews, ISSN 1364-0321, E-ISSN 1879-0690, Vol. 43, p. 1238-1248Article, review/survey (Refereed)
    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.

  • 223.
    Akillioglu, Hakan
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Production Systems.
    Demand Responsive Planning: A dynamic and responsive planning framework based on workload control theory for cyber-physical production systems2015Doctoral thesis, monograph (Other academic)
    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.

  • 224.
    Akillioglu, Hakan
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Production Systems.
    Evolvable Production Systems: Demand Responsive Planning2011Licentiate thesis, comprehensive summary (Other academic)
    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.

  • 225.
    Akillioglu, Hakan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Production Systems.
    Dias-Ferreira, Joao
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Production Systems.
    Onori, Mauro
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Production Systems.
    Characterization of Continuous Precise Workload Control and Analysis of Idleness Penalty2014In: CIE 44 and IMSS14 proceedings, 2014, p. 1998-2011Conference paper (Refereed)
    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.

  • 226.
    Akillioglu, Hakan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Production Systems.
    Ferreira, Joao
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Production Systems.
    Onori, Mauro
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Production Systems.
    Demand responsive planning: workload control implementation2013In: Assembly Automation, ISSN 0144-5154, E-ISSN 1758-4078, Vol. 33, no 3, p. 247-259Article in journal (Refereed)
    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.

  • 227.
    Akillioglu, Hakan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Production Systems.
    Maffei, Antonio
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Production Systems.
    Neves, Pedro
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Production Systems.
    Ferreira, Joao
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Production Systems.
    Operational characterization of evolvable productionsystems2012In: 4th CIRP Conference on Assembly Technologies and Systems – CATS 2012, 2012, p. 85-90Conference paper (Refereed)
    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.

  • 228.
    Akillioglu, Hakan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Production Systems.
    Onori, Mauro
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Production Systems.
    Evolvable production systems and impacts on production planning2011Conference paper (Other academic)
    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.

  • 229.
    Akner, David
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Vehicle Dynamics.
    A method to generate drive cycles from operational data2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis investigates the possibility to develop a method to generate drive cycles for heavy duty vehicles for Scania’s customers. A representative drive cycle is important to simulate realistic driving of vehicles. Trucks that are sold by Scania and other manufacturers are collecting data which are logged from the vehicle’s on-board computer during operations. This data is used for the development of new trucks, and the idea is that with operational data, a drive cycle can be generated which is representative for the operations of a specific truck. The developed methodology generates a drive cycle which is compared against this operational data. By making a first selection of already existing drive cycles and modifying the closest drive cycle to a selection of parameters, a drive cycle which corresponds to the operations of the specific truck can be designed. To compare against the operational data, simulations of the truck performing the drive cycle are conducted, and the results are compared to the truck’s operational data. The simulation tool is an internally developed model at Scania which has been verified against test measurements on trucks. A final methodology to generate drive cycles are developed and it compares the simulated fuel consumption and engine load matrix against operational data. By redesigning the drive cycle in an iterative process, results from simulation of the drive cycle becomes very similar to the operational data.

  • 230.
    Aktas, Stefanos
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Integrated Product Development.
    Wennhall, Thomas
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Integrated Product Development.
    AI - an Untapped Opportunity for Innovation Developing a Screening Tool for AI and Innovation2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    It is known that innovation enables companies to penetrate new markets and achieve higher margins and that technology can contribute to achieving a competitive ad-vantage and growth for organizations. A technology that has as of recently grown to become relevant for organizations is Artificial Intelligence (AI). Even so, previous studies have expressed the difficulty of implementing AI, which motivated this study.

    The main purpose of this study was to develop and test a screening tool that will work as a support in increasing an organization’s utilization of AI and innovation capability. During the course of the study, a great amount of focus was also put into conducting a preliminary analysis in preparation for a larger study that will be dependent on gathering large amounts of quantitative data.

    The research took on a three-phase-process. The first phase focused on gaining basic knowledge in regards to AI, innovation, technology management and model development. The findings in the first phase helped to formulate proper research questions that were applicable to the study.

    After that, the study moved on to the second phase which focused on a more in-depth literature study. This then led on to the development of an appropriate questionnaire for investigating factors that are relevant for AI and innovation, and an assessment model that would be connected to the questionnaire. The questionnaire was used for gathering responses that would be beneficial for the preliminary analysis in the form of a pilot study. The questionnaire and the assessment model together form a screening tool that gives a visual output of an organization’s position in regards to AI and innovation.

    The third and final phase included testing of the created screening tool, analyzing the findings from the pilot study and drawing conclusions from both the developed screening tool, and the results from the pilot study.

    The result from the literature study was the screening tool which takes five di-mensions into consideration that shows relevance to AI and innovation. These di-mensions are Structures, Resources, Methods, Action and Business,eachcontaining areas that exist in organizations that can be adjusted for the sake of the implemen-tation of AI and improvement of innovation management. The screening tool was tested on two separate organizations and managed to reflect these organizations’ AI progress through the assessment model. The screening tool was also applied to the pilot study which resulted in giving indications of what to expect when conducting a larger quantitative study.

    Despite the results gained from this study, it showed that further tests and studies need to be made in order to obtain more viable results. This study will act as a guideline for future studies to attain those results.

  • 231.
    Al Naami, Adam
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy and Climate Studies, ECS.
    Techno-economic Feasibility Study of a Biogas Plant for Treating Food Waste Collected from Households in Kartamantul Region, Yogyakarta2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis presents the potential of biogas production using food waste collected from the region of Kartamantul in Yogyakarta, Indonesia. Biogas can be used for cooking and generating electricity. The study compares two different end uses or markets for utilizing the biogas in the region. The daily food waste collected in the region of Kartamantul is 120 tonnes. This corresponds to a daily biogas production of 13 087 m3. Electricity generated from biogas can replace fossil-based coal electricity while cooking biogas can substitute the common fossil fuel liquefied Petroleum Gas (LPG). The price for selling one kWh of electricity to the state owned enterprise PLN is 16.5 USD cents. The price for selling one m3 of biogas for cooking is 38.5 USD cents, which is equivalent to the available price of LPG. The study finds that the avoided emission due to the substitution of fossil-based coal electricity and cooking LPG-gas is around 64 GgCO2-eq per year.

    Considering the economical results for a life span of 20 years in the first utilization option Biogas for Electricity gives a net present value (NPV) of 2 MUSD while for the utilization option Biogas for Cooking gives a net present value (NPV) of 5.82 MUSD. The breakeven for Biogas for Electricity is 13.8 USD cents per kWhe while for Biogas for Cooking is 25.5 USD cents per m3-biogas. The study concludes that it is feasible to invest in AD plant in the region of Kartamantul where both markets are profitable and environmentally friendly. 

  • 232.
    Al Naami, Mahdi
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Thermal Conversion of MSW a Comparison of the System Performance: Direct Combustion Versus Conversion Through Syngas in CHP Plant2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This thesis is a study comparing two different thermal conversion paths for Municipal Solid Waste (MSW). The comparison will be focused on technical, economic and emission aspects. One path is the direct incineration of the MSW. Meanwhile the other consists of submitting the MSW to the process of gasification obtaining syngas which will be used for the production of energy. The thermal conversion is produced in a Combined Heat and Power system (CHP-system) looking at the economic, emission and technical aspects.

    CHP-incineration plant produces heat and power from mass burning MSW directly without pre-treatment and CHP-gasification plant produces heat and power from converting MSW to syngas in a gasifier and then use the syngas to produce heat and electricity. To get the result of the objective, the following questions have been answered:

    • What is the overall economic performance of the two thermal conversion paths?
    • What are the differences in emission depending on the path selected?
    • What is the overall efficiency?

    The results shows that the most profitable thermal conversion path is directly incinerated MSW in the CHP-incineration since it is a more mature technology and therefore the costs of applying it are much less than applying the other alternative, however there are other economic cases that is the opposite. In case of pollution, thermal conversion of MSW into syngas for production of heat and power is much more environmental friendly and in case of the overall efficiency is the thermal conversion of MSW into syngas higher.

  • 233.
    Al Shadidi, Kamilla
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Oil Cooling of Electric Motor using CFD2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    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.

  • 234.
    Al Taweel, Maher
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    CFD simulering av kallras: Undersökning av temperatur- och luftbeteende intill höga glasfasader och i vistelsezon med golvvärme som en värmekälla2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    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.

  • 235.
    Alallak, Ali
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Machine and Process Technology.
    Deburring of components: A survey of current and future deburring processes2010Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    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.
  • 236. Alam, M M
    et al.
    Barsoum, Zuheir
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Jonsen, P
    Kaplan, A F H
    Haggblad, H A
    Influence of defects on fatigue crack propagation in laser hybrid welded eccentric fillet joint2011In: Engineering Fracture Mechanics, ISSN 0013-7944, E-ISSN 1873-7315, Vol. 78, no 10, p. 2246-2258Article in journal (Refereed)
    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.

  • 237. Alam, M. M.
    et al.
    Barsoum, Zuheir
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    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 joints2010In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 256, no 6, p. 1936-1945Article in journal (Refereed)
    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.

  • 238. Alam, Minhaj M
    et al.
    Barsoum, Zuheir
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    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 joints2009In: 12th NOLAMP proceeding 2009: Nordic Laser Materials Processing Conference / [ed] Erling Dam Mortensen, 2009Conference paper (Other academic)
    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.

  • 239. Alam, Minhaj M
    et al.
    Barsoum, Zuheir
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Jonsén, Pär
    Häggblad, Hans Åke
    Kaplan, Alexander
    Geometrical Aspects of The Fatigue Behaviour of Laser Hybrid Fillet Welds2009In: Proceedings of the Fatigue Design Conference, 2009Conference paper (Refereed)
  • 240. Alam, Minhaj M
    et al.
    Barsoum, Zuheir
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
    Josén, Per
    Häggblad, Hans Åke
    kaplan, Alexander
    Fatigue Behaviour Study of Laser Hybrid Welded Eccentric Fillet Joints - Part I2009In: 12th NOLAMP proceeding 2009: Nordic Laser Materials Processing Conference / [ed] Erling Dam Mortensen, 2009Conference paper (Other academic)
    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.

  • 241. Alameldin, A.
    et al.
    El-Gabry, L. A.
    Fridh, Jens
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Saha, Ranjan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    CFD analysis of suction and pressure side film cooling influence on vane aero performance in a transonic annular cascade2014In: Proceedings of the ASME Turbo Expo, 2014Conference paper (Refereed)
    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.

  • 242.
    Alaniz, Monica
    et al.
    KTH, School of Engineering Sciences (SCI), Mechanics, Structural Mechanics.
    Belyayev, Serhiy
    KTH, School of Engineering Sciences (SCI), Mechanics, Structural Mechanics.
    Bergman, David
    Casselbrant, Gustav
    KTH, School of Engineering Sciences (SCI), Mechanics, Structural Mechanics.
    Honeth, Mark
    KTH, School of Engineering Sciences (SCI), Mechanics, Structural Mechanics.
    Huang, Jiangwei
    KTH, School of Engineering Sciences (SCI), Mechanics, Structural Mechanics.
    Ivchenko, Nickolay
    KTH, School of Electrical Engineering (EES), Space and Plasma Physics.
    Laukkanen, Mikko
    KTH, School of Engineering Sciences (SCI), Mechanics, Structural Mechanics.
    Michelsen, Jacob
    KTH, School of Engineering Sciences (SCI), Mechanics, Structural Mechanics.
    Pronenko, Vira
    KTH, School of Engineering Sciences (SCI), Mechanics, Structural Mechanics.
    Paulson, Malin
    KTH, School of Engineering Sciences (SCI), Mechanics, Structural Mechanics.
    Schlick, Georg
    KTH, School of Engineering Sciences (SCI), Mechanics, Structural Mechanics.
    Tibert, Gunnar
    KTH, School of Engineering Sciences (SCI), Mechanics, Structural Mechanics.
    Valle, Mario
    KTH, School of Engineering Sciences (SCI), Mechanics, Structural Mechanics.
    The SQUID sounding rocket experiment2011In: Proceedings of the 20th ESA Symposium on European Rocket and Balloon Programmes and Related Research, European Space Agency, 2011, p. 159-166Conference paper (Refereed)
    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.

  • 243.
    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, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Microgeneration and Desalination Using Rotary Steam Engine (RTE) Technology2011Conference paper (Refereed)
    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.

  • 244.
    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, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Thermo-economic analysis of a micro-cogeneration system based on a rotary steam engine (RSE)2012In: Applied Thermal Engineering, ISSN 1359-4311, E-ISSN 1873-5606, Vol. 44, p. 11-20Article in journal (Refereed)
    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.

  • 245.
    Alazar, Abebayehu Seifu
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Werner, Mathias
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering, Machine and Process Technology.
    Nicolescu, Cornel Mihai
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Development of cutting force measurement system used in gear hobbing2011In: Proceedings Of The ASME International Design Engineering Technical Conferences And Computers And Information In Engineering Conference, 2011, Vol 8, ASME Press, 2011, p. 47-52Conference paper (Refereed)
    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.

  • 246. Alberdi, A.
    et al.
    Gil-Negrete, N.
    Vinolas, J.
    Kari, Leif
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Nieto, F. J.
    Dynamic characterisation of different magneto-sensitive natural rubbers for application in vibration isolation2010In: Proceedings of ISMA 2010 - International Conference on Noise and Vibration Engineering, including USD 2010, Katholieke Universiteit Leuven , 2010, p. 227-231Conference paper (Refereed)
    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.

  • 247.
    Alberdi-Muniain, Ane
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Structural and vibroacoustics.
    Magneto-sensitive elastomers in vibration isolation2012Doctoral thesis, comprehensive summary (Other academic)
    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.

  • 248.
    Alberdi-Muniain, Ane
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Structural and vibroacoustics.
    Gil-Negrete, N.
    Department of Applied Mechanics, CEIT and Tecnun (University of Navarra).
    Kari, Leif
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Structural and vibroacoustics.
    Direct energy flow measurement in magneto-sensitive vibration isolator systems2012In: Journal of Sound and Vibration, ISSN 0022-460X, E-ISSN 1095-8568, Vol. 331, no 9, p. 1994-2006Article in journal (Refereed)
    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.

  • 249.
    Alberdi-Muniain, Ane
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Structural and vibroacoustics.
    Gil-Negrete, N
    Kari, Leif
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Structural and vibroacoustics.
    Indirect energy flow measurement in magneto-sensitive vibration isolator systems2013In: Applied Acoustics, ISSN 0003-682x, ISSN 0003-682x, Vol. 74, no 4, p. 575-584Article in journal (Other academic)
    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.

  • 250.
    Alberdi-Muniain, Ane
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Structural and vibroacoustics.
    Gil-Negrete, N
    Kari, Leif
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Structural and vibroacoustics.
    Modelling energy flow through magneto-sensitive vibration isolators2013In: International Journal of Engineering Science, ISSN 0020-7225, E-ISSN 1879-2197, Vol. 65, p. 22-39Article in journal (Refereed)
    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.

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