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  • 1.
    Abdellaoui, G.
    et al.
    Telecom Laboratory, Faculty of Technology, University Abou Bekr Belkaid, Tlemcen, Algeria.
    Bolmgren, Karl
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Fuglesang, Christer
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Marchi, A. Zuccaro
    RIKEN, Wako, Japan.
    EUSO-SPB1 mission and science2024In: Astroparticle physics, ISSN 0927-6505, E-ISSN 1873-2852, Vol. 154, p. 102891-, article id 102891Article in journal (Refereed)
    Abstract [en]

    The Extreme Universe Space Observatory on a Super Pressure Balloon 1 (EUSO-SPB1) was launched in 2017 April from Wanaka, New Zealand. The plan of this mission of opportunity on a NASA super pressure balloon test flight was to circle the southern hemisphere. The primary scientific goal was to make the first observations of ultra-high-energy cosmic-ray extensive air showers (EASs) by looking down on the atmosphere with an ultraviolet (UV) fluorescence telescope from suborbital altitude (33 km). After 12 days and 4 h aloft, the flight was terminated prematurely in the Pacific Ocean. Before the flight, the instrument was tested extensively in the West Desert of Utah, USA, with UV point sources and lasers. The test results indicated that the instrument had sensitivity to EASs of ⪆3 EeV. Simulations of the telescope system, telescope on time, and realized flight trajectory predicted an observation of about 1 event assuming clear sky conditions. The effects of high clouds were estimated to reduce this value by approximately a factor of 2. A manual search and a machine-learning-based search did not find any EAS signals in these data. Here we review the EUSO-SPB1 instrument and flight and the EAS search.

  • 2.
    Abudayyeh, H.A.
    et al.
    Department of Physics, Al-Quds University, Jerusalem.
    Barghouthi, I.A.
    Department of Physics, Al-Quds University, Jerusalem.
    Slapak, Rikard
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Nilsson, Hans
    Swedish Institute of Space Physics / Institutet för rymdfysik.
    Centrifugal acceleration at high altitudes above the polar cap: A Monte Carlo simulation2015In: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402, Vol. 120, no 8, p. 6409-6426Article in journal (Refereed)
    Abstract [en]

    A Monte Carlo simulation was used to study the outflow of O+ and H+ ions along three flight trajectories above the polar cap up to altitudes of about 15 RE. Barghouthi (2008) developed a model on the basis of altitude and velocity-dependent wave-particle interactions and a radial geomagnetic field which includes the effects of ambipolar electric field and gravitational and mirror forces. In the present work we improve this model to include the effect of the centrifugal force, with the use of relevant boundary conditions. In addition, the magnetic field and flight trajectories, namely, the central polar cap (CPC), nightside polar cap (NPC), and cusp, were calculated using the Tsyganenko T96 model. To simulate wave-particle interactions, the perpendicular velocity diffusion coefficients for O+ ions in each region were determined such that the simulation results fit the observations. For H+ ions, a constant perpendicular velocity diffusion coefficient was assumed for all altitudes in all regions as recommended by Nilsson et al. (2013). The effect of centrifugal acceleration was simulated by considering three values for the ionospheric electric field: 0 (no centrifugal acceleration), 50, and 100 mV/m. It was found that the centrifugal acceleration increases the parallel bulk velocity and decreases the parallel and perpendicular temperatures of both ion species at altitudes above about 4 RE. Centrifugal acceleration also increases the temperature anisotropy at high altitudes. At a given altitude, centrifugal acceleration decreases the density of H+ ions while it increases the density of O+ ions. This implies that with higher centrifugal acceleration more O+ ions overcome the potential barrier. It was also found that aside from two exceptions centrifugal acceleration has the same effect on the velocities of both ions. This implies that the centrifugal acceleration is universal for all particles. The parallel bulk velocities at a given value of ionospheric electric field were highest in the cusp followed by the CPC followed by the NPC. In this study a region of no wave-particle interaction was assumed in the CPC and NPC between 3.7 and 7.5 RE. In this region the perpendicular temperature was found to decrease with altitude due to perpendicular adiabatic cooling.

  • 3.
    Adolfsson, Anton
    Mälardalen University, School of Innovation, Design and Engineering.
    Defining Next.Generation Modular Test Systems for Space Computers using Model-Based Systems Engineering: Defining space data handling test system using MBSE2024Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The increasing complexity of systems and the demand for increasing implemented functionalit-ies within the systems necessitate a paradigm shift in development approaches. While traditionalsystems engineering relies heavily on textual documentation, the future calls for a more stream-lined, digital method such as Model-Based Systems Engineering (MBSE). MBSE utilises models tostore data, mitigating textual ambiguity and providing stakeholders with a unified source of inform-ation. Despite its potential, the adoption of MBSE presents challenges because of the need of newpractitioner skill-sets.

    The thesis investigates the feasibility of implementing an easily adoptable MBSE, using a limitedset of SysML elements and diagrams, approach within the space industry. Through the developmentof guidelines, steps, and goals, a model of an industry-related system is constructed. The createdmodel serves as a demonstration to industry engineers, evaluating the suitability of the proposedguidelines.

    The thesis concludes the need for maturity of MBSE, its tools, and the need for harmonisationwithin the space industry to establish acceptance among the practitioners. These are the crucialpoints where development and refinements are needed to gain the trust and interest of the end usersof the modelling activities and adopting the proposed methods.i   

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  • 4.
    Aevan, Nadjib Danial
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems.
    MDO Framework for Design of Human PoweredPropellers using Multi-Objective Genetic Algorithm2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis showcases the challenges, downsides and advantages to building a MultiDisciplinary Optimization (MDO) framework to automate the generation of an efficientpropeller design built for lightly loaded operation, more specifically for humanpowered aircrafts. Two years ago, a human powered aircraft project was initiatedat Linköping University. With the help of several courses, various students performedconceptional design, calculated and finally manufactured a propeller bymeans of various materials and manufacturing techniques. The performance ofthe current propeller is utilized for benchmarking and comparing results obtainedby the MDO process.The developed MDO framework is constructed as a modeFRONITER project wereseveral Computer Aided Engineering softwares (CAE) such as MATLAB, CATIAand XFOIL are connected to perform multiple consequent optimization subprocesses.The user is presented with several design constraints such as blade quantity,required input power, segment-wise airfoil thickness, desired lift coefficientetc. Also, 6 global search optimization algorithms are investigated to determinethe one which generate most efficient result according to several set standards.The optimization process is thereafter initialized by identifying the most efficientchord distribution with a help of an initial blade cross-section which has been previouslyused in other human powered propellers, the findings are thereafter usedto determine the flow conditions at different propeller stations. Two different aerodynamicoptimized shapes are generated with the help of consecutively performedsubprocesses. The optimized propeller requires 7.5 W less input power to generatenearly equivalent thrust as the original propeller with a total efficiency exceedingthe 90 % mark (90.25 %). Moreover, the MDO framework include an automationprocess to generate a CAD design of the optimized propeller. The generatedCAD file illustrates a individual surface blade decrease of 12.5 % compared tothe original design, the lightweight design and lower input power yield an overallpropulsion system which is less tedious to operate.

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    MDO Framework for Design of Human Powered Propellers using Multi-Objective Genetic Algorithm
  • 5. Agarwal, Anurag
    et al.
    Dowling, Ann P.
    Shin, Ho-Chul
    Graham, Will
    Sefi, Sandy
    KTH, School of Computer Science and Communication (CSC), Numerical Analysis and Computer Science, NADA.
    Ray-tracing approach to calculate acoustic shielding by a flying wing airframe2007In: AIAA Journal, ISSN 0001-1452, E-ISSN 1533-385X, Vol. 45, no 5, p. 1080-1090Article in journal (Refereed)
    Abstract [en]

    The "silent aircraft" is in the form of a flying wing with a large wing planform and a propulsion system that is embedded in the rear of the airframe with intakes on the upper surface of the wing. Thus a large part of the forward-propagating noise from the intake ducts is expected to be shielded from observers on the ground by the wing. Acoustic shielding effects can be calculated by solving an external acoustic scattering problem for a moving aircraft. In this paper, acoustic shielding effects of the silent aircraft airframe are quantified by a ray-tracing method. The dominant frequencies from the noise spectrum of the engines are sufficiently high for ray theory to yield accurate results. It is shown that, for low-Mach number homentropic flows, a condition satisfied approximately during takeoff and approach, the acoustic rays propagate in straight lines. Thus, from Fermat's principle it is clear that classical geometrical optics and geometrical theory of diffraction solutions are applicable to this moving-body problem as well. The total amount of acoustic shielding at an observer located in the shadow region is calculated by adding the contributions from all the diffracted rays (edge-diffracted and creeping rays) and then subtrading the result from the incident field without the airframe. The three-dimensional ray-tracing solver is validated by comparing the numerical solutions with analytical high-frequency asymptotic solutions for canonical shapes. Experiments on a model-scale geometry have been conducted in an anechoic chamber to test the applicability of the ray-tracing technique. The results confirm the accuracy of the approach, which is then applied to a CAD representation of a prototype silent aircraft design. As expected, the flying wing configuration provides very significant ground shielding (in excess of 10 dB at all locations) of a source above the airframe.

  • 6.
    Aghaali, Habib
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Internal Combustion Engines.
    Ångström, Hans-Erik
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Internal Combustion Engines.
    Turbocharged SI-Engine Simulation with Cold and Hot-Measured Turbocharger Performance Maps2012In: Proceedings of ASME Turbo Expo 2012, Vol 5, ASME Press, 2012, p. 671-679Conference paper (Refereed)
    Abstract [en]

    Heat transfer within the turbocharger is an issue in engine simulation based on zero and one-dimensional gas dynamics. Turbocharged engine simulation is often done without taking into account the heat transfer in the turbocharger. In the simulation, using multipliers is the common way of adjusting turbocharger speed and parameters downstream of the compressor and upstream of the turbine. However, they do not represent the physical reality. The multipliers change the maps and need often to be different for different load points. The aim of this paper is to simulate a turbocharged engine and also consider heat transfer in the turbocharger. To be able to consider heat transfer in the turbine and compressor, heat is transferred from the turbine volute and into the compressor scroll. Additionally, the engine simulation was done by using two different turbocharger performance maps of a turbocharger measured under cold and hot conditions. The turbine inlet temperatures were 100 and 600°C, respectively. The turbocharged engine experiment was performed on a water-oil-cooled turbocharger (closed waste-gate), which was installed on a 2-liter gasoline direct-injected engine with variable valve timing, for different load points of the engine. In the work described in this paper, the difference between cold and hot-measured turbocharger performance maps is discussed and the quantified heat transfers from the turbine and to/from the compressor are interpreted and related to the maps.

  • 7.
    Agües Paszkowsky, Núria
    et al.
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab. Research Institutes of Sweden, Unit for Data Center Systems and Applied Data Science, Sweden.
    Brännvall, Rickard
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab. Research Institutes of Sweden, Unit for Data Center Systems and Applied Data Science, Sweden.
    Carlstedt, Johan
    Research Institutes of Sweden, Unit for Data Center Systems and Applied Data Science, Sweden.
    Milz, Mathias
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Kovács, György
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Liwicki, Marcus
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Embedded Internet Systems Lab.
    Vegetation and Drought Trends in Sweden’s Mälardalen Region – Year-on-Year Comparison by Gaussian Process Regression2020In: 2020 Swedish Workshop on Data Science (SweDS), IEEE, 2020Conference paper (Refereed)
    Abstract [en]

    This article describes analytical work carried out in a pilot project for the Swedish Space Data Lab (SSDL), which focused on monitoring drought in the Mälardalen region in central Sweden. Normalized Difference Vegetation Index (NDVI) and the Moisture Stress Index (MSI) – commonly used to analyse drought – are estimated from Sentinel 2 satellite data and averaged over a selection of seven grassland areas of interest. To derive a complete time-series over a season that interpolates over days with missing data, we use Gaussian Process Regression, a technique from multivariate Bayesian analysis. The analysis show significant differences at 95% confidence for five out of seven areas when comparing the peak drought period in the dry year 2018 compared to the corresponding period in 2019. A cross-validation analysis indicates that the model parameter estimates are robust for temporal covariance structure (while inconclusive for the spatial dimensions). There were no signs of over-fitting when comparing in-sample and out-of-sample RMSE.

  • 8. Ahlgren, Niklas
    et al.
    Karlsson, Thomas
    Larsson, Robin
    Spacecraft Department, OHB Sweden, Sweden.
    Noteborn, Ron
    PRISMA Mission Extension: Adapting Mission Operations to New and Changing Mission Objectives2012In: SpaceOps 2012 Conference, American Institute of Aeronautics and Astronautics, 2012Conference paper (Refereed)
    Abstract [en]

    The PRISMA in-orbit test-bed was launched in June 2010 to demonstrate strategies and technologies for formation flying and rendezvous. OHB Sweden is the prime contractor for the project which is funded by the Swedish National Space Board (SNSB) with support from DLR, CNES, and DTU. In early September of 2011, 15 months after launch, all primary mission objectives of the PRISMA formation flying satellites had been achieved and mission success was declared. Since a significant amount of delta-V capability still remained an open call for new experiments was issued, inviting both old and new experimenters to use the capabilities of the formation. Several interested parties took the opportunity to perform their own experiments with an existing platform, each coming with new mission objectives not previously planned to be flown on the PRISMA satellites. Some of these experiments were close to what had already been achieved within the nominal mission, but some included new ways of using the formation not envisioned by the spacecraft designers. The new experiments span from data collection in specific relative orbits, with a separation from a few meters to several kilometers, to entirely new modules within the on-board software. Changing from a pre-planned technology demonstration mission to operating a commercial resource required adaptation of the original operational concept, taking into account the different levels of experience of the customers and managing the satellites between experiments. This paper describes how these new mission objectives were integrated in operations and how a sometimes very short turn-around between initial concept and experiment execution was implemented with the aid of well established validation processes, high degrees of on-board autonomy and a flexible operations team.

  • 9.
    Ahluwalia, Arvind
    Mälardalen University, School of Innovation, Design and Engineering.
    Computer Controlled Direct Descent2017Independent thesis Basic level (degree of Bachelor), 180 HE creditsStudent thesis
    Abstract [en]

    How an aircraft performs its approach and descent towards an airport today has got big potential for improvements. It's mainly the environmental impact and safety that can, and must, be improved for a sustainable future in aviation. "Green Approaches" is a small, yet relatively well-known, optimized approach system mainly used by Scandinavian Airlines on Arlanda airport. Unfortunately "Green Approaches" aren't used often enough, due to the simple reason that it doesn't work very well during heavy traffic. Luckily further research is being done in this field to further optimize an aircraft’s approach. As of today, the most forward going research is being done by the FAA and NASA, and their new system is called NextGen OPD. The system is not fully developed yet but their goals are, as previously mentioned, to optimize today's aircraft approach. In this report the focus will also be set on improving aircraft approaches, although not by optimizing today’s system like the FAA and NASA. Instead, a whole new concept of how aircraft approach airports will be developed. The reason that a brand new concept will be developed is simple, optimizing today's aging system will not be sustainable for the future. Also, optimizing an aging system has its limits. By designing a whole new concept, a steady ground will be laid and it shall be sustainable for the coming century's technology. The new concept will be called ”C.C.D.D.”, Computer Controlled Direct Descent, and will have a lot of goals and expectations to fulfill. As hinted in the name, the new concept is built on the idea that a computer will be controlling the whole approach, and therefore the "Human factor" will more or less be eliminated. Although the main purpose of a new approach system is to decrease the negative environmental impact, by decreasing the fuel consumption during the approach. The new concept will also decrease the noise an aircraft makes during the descent and increase the possibility for a greater traffic flow in the airport’s airspace. The end result will be a "win-win" for everyone involved. An environmentally friendly aircraft approach is necessary for a sustainable future in aviation. C.C.D.D. is a system that will pay for itself with time, because of the decreased fuel consumption for airliners. The system also has the ability to be expanded to computer control departing aircrafts, due to the systems highly computerized structure and integration with airplanes autopilot.

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  • 10.
    Ahlén, Kritsoffer
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Rosén, Malin
    Mälardalen University, School of Innovation, Design and Engineering.
    Simulering som konstruktionsstöd2013Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
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    Simulering som konstruktionssöd
  • 11.
    Ahmad, Mustafa
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Boukli, Tarék
    Mälardalen University, School of Innovation, Design and Engineering.
    Continuing Airworthiness Management Exposition: For Priority Aero Maintenance2012Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The economic crisis has affected the airline industry as much as it has affected all other industries in the world. The small airlines and maintenance organisations must find new opportunities and options in order to survive the harsh crisis. Priority Aero Maintenance is now an approved maintenance organisation performing maintenance on aircrafts, engines and components. The company sees economic gains in the future by becoming an approved organisation that follows the European Aviation Safety Agency guidelines (EASA) and meets the requirements outlined in the rules of Part-M.

    In order for the company to become an approved organization, responsible for continuing airworthiness of aircraft, a handbook should be presented to the local authority. This handbook describes the company’s responsibility for the continuing airworthiness in order for the authorities to get an insight into the company and its work.

    This thesis resulted in a draft of CAME (Continuing Airworthiness Management Exposition) and this draft has been approved by Priority Aero Maintenance.

    The CAME will in the future be used by the company as a basis for developing a more detailed manual to be presented to and approved by the Swedish Aviation Authority (Transportstyrelsen).

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  • 12.
    Ahn, Myeonghwan
    et al.
    Mechanical Engineering Research Institute, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 34141, South Korea.
    Lee, Duck-Joo
    Mihaescu, Mihai
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences (SCI), Mechanics.
    A numerical study on near-field pressure fluctuations of symmetrical and anti-symmetrical flapping modes of twin-jet using a high-resolution shock-capturing scheme2021In: Aerospace Science and Technology, ISSN 1270-9638, E-ISSN 1626-3219, p. 107147-107147, article id 107147Article in journal (Refereed)
    Abstract [en]

    Screeching supersonic jets appears at off-design operating conditions and is perceived as an intense tonal noise. In a twin nozzle configuration, mutual interactions between the two jet plumes may occur with various coupling modes developing depending on the operating conditions and lateral distance between the jets. The investigation of the detailed flow behaviors and near-field pressure fluctuations with relevance to the twin jets system, the analysis of the developed instabilities, will enhance understanding of fundamental features associated with jets located close to each other.

    In the present study, the single jet is considered first to assess the large eddy simulation (LES) approach used and the near-field pressure fluctuation predictions. Based on the validated solver, twin jets are simulated. Two different twin-nozzle configurations having different separation distance or nozzle-to-nozzle centerline spacing are scrutinized for the same Mach number of 1.358. Notably, the twin jets are screeching by the coupling mode for both set-ups; however, the case of closer inter-nozzle distance presents a symmetrical dominant flapping mode, while the other case shows an anti-symmetrical flapping mode. The strength of the pressure fluctuation at the fundamental frequency changes depending on the location of the observer point (upstream or downstream) and the reference plane (twin-jet and normal to the twin-jet plane). The screech tones of the two cases, observable in the upstream region, are significantly different in the normal to the twin-jet plane direction because of the phase difference of fluctuating pressure. However, the first harmonic component remains strong, regardless of the flapping mode. It is also observed that, at the fundamental frequency, the amplitude of the pressure fluctuation at downstream locations is found to be strong in the normal to the twin-jet plane when the symmetrical flapping mode occurs. This feature is also observed in the twin-jet plane in the case of the opposite mode. By analyzing the developed vertical structures and performing correlation analyses of pressure fluctuations along jet shear layers, the periodicity of the flow in the downstream region with relevance to the fundamental frequency is revealed.

  • 13.
    Ahn, MyeongHwan
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics.
    Mihaescu, Mihai
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics.
    Effects of Temperature on the Characteristics of Twin Square Jets by Large Eddy Simulations2022In: AIAA Science and Technology Forum and Exposition, AIAA SciTech Forum 2022, American Institute of Aeronautics and Astronautics (AIAA) , 2022, article id AIAA 2022-0681Conference paper (Refereed)
    Abstract [en]

    In this study, we investigate the effects of temperature on the aerodynamic and aeroacoustics characteristics of twin square jets. Implicit Large Eddy Simulations (ILES) are performed for twin jets with a fixed nozzle pressure ratio (NPR) of 3.0 and temperature ratios (TR) of 1.0, 2.0, 4.0, and 7.0. A second-order central scheme is used to resolve acoustic waves, and an artificial dissipation model is applied to capture shock waves and to suppress non-physical oscillations. In addition, the variation of a specific heat ratio as function of temperature is considered under the chemical equilibrium assumption. The numerical results show that the length of potential core is reduced with the increase of temperature due to the enhanced mixing in jet shear layers which can be estimated by turbulent kinetic energy (TKE). Meanwhile, the fluctuations of the transverse velocity show different trends between the cases within the corresponding potential core length, which can be associated with the screeching phenomena of the twin-jet. As temperature increases, the convection Mach number in the jet shear layers is also increased so that the Mach wave is generated for TR of 2.0, 4.0, and 7.0. However, a crackle noise is only observed for TR of 4.0 and 7.0, whose generation is identified by the skewness and kurtosis factors. Relatively low temperature jets (TR of 1.0 and 2.0) are screeching so that peaks are observed in the spectra obtained upstream. On the other hand, broadband component is gradually increased when the jets are heated, and the largest increase is observed at the location exposed to the Mach wave radiation.

  • 14.
    Ahn, MyeongHwan
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Mihaescu, Mihai
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics.
    Karnam, Aatresh
    University of Cincinnati.
    Gutmark, Ephraim
    Aerospace Engineering, University of Cincinnati.
    Large-eddy simulations of flow and aeroacoustics of twin square jets including turbulence tripping2023In: Physics of fluids, ISSN 1070-6631, E-ISSN 1089-7666, Vol. 35, no 6Article in journal (Refereed)
    Abstract [en]

    In this study, we investigate the flow and aeroacoustics of twin square (i.e., aspect ratio of 1.0) jets by implicit large-eddy simulations (LESs) under a nozzle pressure ratio of 3.0 and a temperature ratio of 1.0 conditions. A second-order central scheme coupled with a modified Jameson's artificial dissipation is used to resolve acoustics as well as to capture discontinuous solutions, e.g., shock waves. The flow boundary layer inside of the nozzle is tripped, using a small step in the convergent section of the nozzle. The time-averaged axial velocity and turbulent kinetic energy of LES with boundary layer tripping approaches better to particle image velocimetry experimental data than the LES without turbulence tripping case. A two-point space–time cross-correlation analysis suggests that the twin jets are screeching and are coupled to each other in a symmetrical flapping mode. Intense pressure fluctuations and standing waves are observed between the jets. Spectral proper orthogonal decomposition (SPOD) confirms the determined mode and the relevant wave propagation. The upstream propagating mode associated with the shock-cell structures is confined inside jets. Far-field noise obtained by solving Ffowcs Williams and Hawkings equation is in good agreement with the measured acoustic data. The symmetrical flapping mode of twin jets yields different levels of the screech tone depending on observation planes. The tonalities—the fundamental tone, second and third harmonics—appear clearly in the far-field, showing different contributions at angles corresponding to the directivities revealed by SPOD.

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  • 15.
    Aires, Filipe
    et al.
    LERMA, Observatoire de Paris, Paris, France; Estellus, Paris, France.
    Prigent, Catherine
    LERMA, Observatoire de Paris, Paris, France; Estellus, Paris, France.
    Buehler, Stefan A.
    Universität Hamburg, Hamburg, Germany.
    Eriksson, Patrick
    Chalmers University of Technology, Gothenburg, Sweden.
    Milz, Mathias
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Crewell, Susanne
    Cologne University, Cologne, Germany.
    Towards more realistic hypotheses for the information content analysis of cloudy/precipitating situations – Application to a hyperspectral instrument in the microwave2019In: Quarterly Journal of the Royal Meteorological Society, ISSN 0035-9009, E-ISSN 1477-870X, Vol. 145, no 718, p. 1-14Article in journal (Refereed)
    Abstract [en]

    Information Content (IC) analysis can be used before an instrument is built to estimate its retrieval uncertainties and analyse their sensitivity to several factors. It is a very useful method to define/optimise satellite instruments. IC has shown its potential to compare instrument concepts in the infrared or the microwaves. IC is based on some hypotheses such as the the gaussian character of the Radiative Transfer (RT) and instrument errors, the first guess errors (Gaussian character, std and correlation structure), or the linearisation of the RT around a first guess. These hypotheses are easier to define for simple atmospheric situations. However, even in the clear‐sky case, their complexity has never ceased to increase towards more realism, to optimise the assimilation of satellite measurements in the Numerical Weather Prediction (NWP) systems. In the cloudy/precipitating case, these hypotheses are even more difficult to define in a realistic way as many factors are still very difficult to quantify. In this study, several tools are introduced to specify more realistic IC hypotheses than the current practice. We focus on the microwave observations as this is more pertinent for clouds and precipitation. Although not perfect, the proposed solutions are a new step towards more realistic IC assumptions of cloudy/precipitating scenes. A state‐dependence of the RT errors is introduced, the first guess errors have a more complex vertical structure, the IC is performed simultaneously on all the hydrometeors to take into account the contamination effect of the RT input uncertainties, and the IC is performed on a diversified set of cloudy/precipitating scenes with well‐defined hydrometeor assumptions. The method presented in this study is illustrated using the HYperspectral Microwave Sensor (HYMS) instrument concept with channels between 6.9 and 874 GHz (millimeter and sub‐millimeter regions). HYMS is considered as a potential next generation microwave sounder.

  • 16.
    Aires, Filipe
    et al.
    Estellus, Paris, France;LERMA, Observatoire de Paris, Paris, France;Water Center, Columbia University, New York, USA.
    Prigent, Catherine
    Estellus, Paris, France;LERMA, Observatoire de Paris, Paris, France.
    Orlandi, Emiliano
    Institute for Geophysics and Meteorology, University of Cologne, Cologne, Germany.
    Milz, Mathias
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Eriksson, Patrick
    Global Environmental Measurements and Modeling, Chalmers University of Technology, Gothenburg, Sweden.
    Crewell, Susanne
    Institute for Geophysics and Meteorology, University of Cologne, Cologne, Germany.
    Lin, Chung-Chi
    Earth Observation Projects Department, ESA, ESTEC, Noordwijk, Netherlands.
    Kangas, Ville
    Earth Observation Projects Department, ESA, ESTEC, Noordwijk, Netherlands.
    Microwave hyperspectral measurements for temperature and humidity atmospheric profiling from satellite: The clear-sky case2015In: Journal of Geophysical Research - Atmospheres, ISSN 2169-897X, E-ISSN 2169-8996, Vol. 120, no 21, p. 11334-11351Article in journal (Refereed)
    Abstract [en]

    This study investigates the benefits of a satellite HYper-spectral Microwave Sensor (HYMS) for the retrieval of atmospheric temperature and humidity profiles, in the context of Numerical Weather Prediction (NWP). In the infrared, hyper-spectral instruments have already improved the accuracy of NWP forecasts. Microwave instruments so far only provide observations for a limited number of carefully selected channels. An information content analysis is conducted here to assess the impact of hyper-spectral microwave measurements on the retrieval of temperature and water vapor profiles under clear-sky conditions. It uses radiative transfer simulations over a large variety of atmospheric situations. It accounts for realistic observation (instrument and radiative transfer) noise and for a priori information assumptions compatible with NWP practices. The estimated retrieval performance of the HYMS instrument is compared to those of the microwave instruments to be deployed on board the future generation of European operational meteorological satellites (MetOp-SG). The results confirm the positive impact of a HYMS instrument on the atmospheric profiling capabilities compared to MetOp-SG. Temperature retrieval uncertainty, compared to a priori information, is reduced by 2 to 10%, depending on the atmospheric height, and improvement rates are much higher than what will be obtained with MetOp-SG. For humidity sounding these improvements can reach 30%, a significant benefit as compared to MetOp-SG results especially below 250 hPa. The results are not very sensitive to the instrument noise, under our assumptions. The main impact provided by the hyper-spectral information originates from the higher resolution in the O2 band around 60 GHz. The results are presented over ocean at nadir but similar conclusions are obtained for other incidence angles and over land.

  • 17.
    Akbarpour, Sahar
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Lightweight Structures. KTH.
    Enhanced Composite Joint Performance through Interlacement of Metal Inserts2021Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The work in this thesis investigates bolted joints in fibre reinforced composites with particular focus on a novel insert concept. The concept is characterised by replacing all composite plies with stacked metal patches, locally around a bolt hole, so that they jointly form a solid metal reinforcement. An extensive experimental study is presented together with finite element analysis of the studied cases.

    Reinforcing bolt holes with high-strength metals improves the bearing load capacity of the composite laminates. True enhancement of the joint performance however requires that the open-hole tensile strength is improved as well. The work started with tests of pin-loaded and open-hole tensile specimens with inserts, and significant improvement of the bearing load capacity was found. The initial tests enabled more informed design, and insert configurations having sufficient open-hole tensile strength could thereby be manufactured and tested. In parallel, composite-metal joints were numerically modelled to simulate and analyse the mechanical performance of the joints and gain a better understanding of the governing damage mechanisms.

    The performance of the joints was eventually investigated by means of experiments on single-shear, single- and double-bolt specimens, with and without inserts. The allowable bolt distance and the influence from the bolt tightening torque were also examined.

    The initial samples had inserts of stainless steel. Later, specimens with titanium alloy inserts were also included in the test series. Various insert configurations were designed to study the effects of different features in the composite-metal bond lines. The numerical simulations of the composite--metal interfaces were performed with two types of models, one joining the two materials directly to each other, without modelling any adhesive film in between, and the other including an elastic representation of the adhesive layer. The experimental results were then used to support verification of the results from the simulations.

    The final assessment of the concept was performed on insert configurations designed either for pure tensile loading or for more general (bi-directional) loading conditions, and the bearing load capacity, open-hole tensile strength and the performance of bolted joints were compared for cases with different inserts. While higher bearing strength improvement was achieved when the holes were reinforced with inserts of stainless steel, reinforcement with inserts of titanium was even more successful since it improved virtually all studied aspects of the joints considerably.

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  • 18.
    Akbarpour, Sahar
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Lightweight Structures.
    Hallström, Stefan
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Lightweight Structures.
    Strength improvement of bolted joints in composite materials by use of patched metal inserts2020In: Composite structures, ISSN 0263-8223, E-ISSN 1879-1085, Vol. 52, article id 112628Article in journal (Refereed)
    Abstract [en]

    Metal inserts are occasionally used to improve bearing load capacity of bolted joints in laminated composite materials. This paper investigates a new reinforcement concept where inserts are built by locally replacing composite plies with metal patches of various diameters, surrounding the holes. The inserts are built during composite manufacturing by alternately placing the metal patches through the thickness of the laminate at locations where holes are to be drilled after consolidation. An extensive experimental study including pin‐ loaded, open–hole tensile, and single‐shear testing of bolted specimens is presented. Considerable improve- ment of the bearing strength – 50‐60% – is attained for pin‐loaded specimens with inserts, demonstrating the potential of the reinforcement concept. The open–hole tensile tests show that the by‐pass strength can be maintained or even improved with up to 20% if the inserts are properly designed. Finally, the results from the single‐shear tests of bolted joints show more than 25% improvement in strength for reinforced single‐ and double‐bolt specimens. It is possible that the inserts would maintain clamping pressure over time, which could then almost double the imrovement (47%) for bolted joints.

  • 19.
    Akner, Malcolm
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Validating results from the Molten Salt Reactor Experiment by use of turbulent CFD simulations: A study of a modified U-tube shell-and-tube primary heat exchanger and radiator with molten salts2021Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Background

    Nuclear reactors utilizing molten fuels rather than solid fuels show a massive advantage in energy yield, waste handling and safety features. The only successful reactor utilizing a molten fuel was called the ‘Molten Salt Reactor Experiment’ (MSRE), built and operated in the Oak Ridge national laboratory (ORNL) in Tennessee, U.S.A. during the 1960s. The molten salts in question are fluoride compounds under the name of “FLiBe”. In this thesis, the heat exchangers of the MSRE are modelled and simulated, with the aim to test whether current computational fluid dynamics (CFD) software and mathematical models can accurately predict molten salt heat transfer behaviour. 

    Methods

    All programs used are open-source and/or free-access to facilitate open collaboration between researchers in this growing field. All models and findings produced in this thesis are free to use for future research.

    • The program Onshape was used to draw CAD-models based on hand-drawn technical documents released by ORNL.
    • Several programs, e.g., Simscale and Salome, were used to create high detailed meshes of the heat exchangers.
    • The CFD software Simscale and OpenFOAM have been used to simulate the heat exchangers, using the 𝑘 − 𝜔 𝑆𝑆𝑇 Reynolds averaged Navier-Stokes (RANS) turbulence model to perform a multiregion conjugate heat transfer (CHT) analysis.
    • The program Paraview has been used for all post-processing on the large datasets. 

    Results

    • A working toolchain with open-source programs for CFD has been identified.
    • Highly detailed, full-scale and accurate CAD-drawings of the two heat exchangers have been produced.
    • Models have been finely meshed, containing tens of millions of cells, with good quality measures.
    • The simulations produced physically sound and valuable data: 
      • Great heat transfer predictive capability with high accuracy to the data presented by ORNL.
      • Pressure data showed a consistent over-prediction with a factor of ~2. Possibility of error within the MSRE measurement. 

    Conclusions

    • CHT using modern turbulence methods work well for the intended purpose and can be used by industry to simulate molten salt heat transfer.
    • Open-source programs perform well and can be used by researchers to share ideas and progress.
    • Doubts around certain measurements from the MSRE, showing large uncertainties.
    • Future projects have been outlined to continue the work performed in this thesis.
    • Molten salt reactors show fantastic promise as an energy generation method and should be seriously considered for the future of clean, reliable energy.
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  • 20.
    Al, Goran
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Boge, Kasper
    Mälardalen University, School of Innovation, Design and Engineering.
    Metod för att säkra innehållet i Scania lastbilars underhållsprogram: Tillämpning av MSG-3 processen från flygindustrin2012Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
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    Rapport - Scania
  • 21.
    Al Hamrani, Emad
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Al-Dulaimi, Anmar
    Mälardalen University, School of Innovation, Design and Engineering.
    Framtida installationskrav på Electronic Flight Bags (EFB): Med hänsyn till litiumbatterier2017Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This degree project studies the future regulations for the installation of electronic flight bags (EFB) with focus on the hardware and its safety implications in which the task was given by Bromma Air Maintenance (BAM). The aim is to ease the operator to handle issues dealing with EFB; such as lithium battery fire in the cockpit, placement of EFB in the cockpit, etc. This also addresses flight safety, flight controls, emergency evacuation and solutions in dealing with such issues. Flight safely is a vital factor to be considered since it jeopardizes lives. As recent reports indicate an increase in lithium battery powered devices incidents on aircrafts, this paves the way to find new solutions and procedures to mitigate them. By studying the current regulations, Acceptable Means of Compliance (AMC), Advisory Circular (AC) regarding the usage/installation of EFB and future regulation draft (NPA) this study analyzed the changes, which indicated that there were not many significant changes made to the future regulation (new AMC). Although many chapter of the current AMC have been removed and introduced into a new section under AMC & GM (Guidance Material). Different placement of the EFB in cockpit has also been studied in this degree project, which has shown that depending on the placement choice of the aircraft operator there are advantages and disadvantages. This follows by studying the lithium (Li-ion) batteries: technology, mitigation of fire and procedures for lithium battery fire while also studying the recent incidents regarding lithium batteries fire and explosion in commercial and cargo flights. The solutions consist of using the latest technology to propose a new approach to charge the batteries, and store the burning batteries as well. This lead to a smart inductive charger and a smart fire contamination bag to be integrated into the procedures.

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    Framtida installationskrav på EFB
  • 22.
    Al-anbagi, Ali
    et al.
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Khalil, Dani
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Utformning avlandningsbanors överbyggnad med hänsyn till slitlagrets bärförmåga2020Independent thesis Basic level (professional degree), 180 HE creditsStudent thesis
    Abstract [en]

    n this study, the design of the runway structure of the runways is studied in order tocompare different material compositions in the pavement. This is done with the helpof a survey, the program FAARFIELD and peer reviewed studies. Generally, thereare two different types of road structures in an airfield, rigid and flexible (concreteand asphalt). The result obtained shows the difference between the differentdimensions and the material content of the different types of road structures, whenthey are loaded with either heavy or light aircraft models. These results are based ona design period that has been selected for 20 years. In contrast, the stiffness of theconcrete was much higher than the asphalt stiffness, which means that it is better touse concrete in large commercial airports. According to the CDF diagram (thediagram showing whether the structural design conditions are met), the damagecaused by the aircraft is approximately at the same location on the runway for bothsuperstructures, it also means that flexible superstructure maintenance needs to bedone more often, compared to rigid superstructures. The fact that the asphalt has alower modulus of elasticity than the concrete is also a reason why maintenance forflexible superstructures needs to be done more often. However, when the roadstructures became heavily loaded, the total demanding thickness for the rigid roadstructure is calculated to be 760 mm and for the flexible road structure 710 mm.

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  • 23.
    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.

  • 24.
    Alarcón, José Faúndez
    et al.
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Sasaki, Kenzo
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Hanifi, Ardeshir
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Larsson, Roger
    Saab Aeronautics, Bröderna Ugglas gata, SE-58188, Linköping, Sweden, Bröderna Ugglas gata.
    Henningson, Dan S.
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    REACTIVE CONTROL OF BYPASS TRANSITION IN A WING BOUNDARY LAYER2022In: 33rd Congress of the International Council of the Aeronautical Sciences, ICAS 2022, International Council of the Aeronautical Sciences , 2022, p. 3037-3047Conference paper (Refereed)
    Abstract [en]

    This investigation deals with the numerical implementation of a data-driven method for reactive control of the boundary-layer over a NACA0008 airfoil. The aim of this work is to evaluate the performance of controller in damping the flow disturbances and its efficiency in delaying laminar-turbulent transition. We focus our attention on the bypass transition scenario caused by free-stream turbulence. In this scenario, the perturbations in the wing boundary-layer develop into streaky structures. We show that this data-driven method is effective in decreasing the wall shear stress and disturbance energy at the objective location, and this damping is sustained downstream of the objective location. However, further downstream, the fluctuations grow again reaching amplitudes similar to those in the uncontrolled case.

  • 25.
    Albers, Roland
    et al.
    Institute of Applied Physics, University of Bern, Bern, Switzerland.
    Andrews, Henrik
    Norwegian University of Science and Technology, Høgskoleringen 1, Trondheim, Norway.
    Boccacci, Gabriele
    Sapienza University of Rome, Rome, Italy.
    Pires, Vasco D.C.
    DEMec, Faculty of Engineering, University of Porto, R. Dr. Roberto Frias, Porto, Portugal; Chair of Designing Plastics and Composite Materials, Department of Polymer Engineering and Science, Montanuniversitaet Leoben, Otto Glöckel-Straße 2, Leoben, Austria.
    Laddha, Sunny
    Space Research Institute Graz, Austrian Academy of Sciences, Schmiedlstraße 6, Graz, Austria.
    Lundén, Ville
    Department of Electronics and Nanotechnology, School of Electrical Engineering, Aalto University, Maarintie 8, Espoo, Finland.
    Maraqten, Nadim
    University of Stuttgart, Pfaffenwaldring 29, Stuttgart, Germany.
    Matias, João
    Department of Aeronautics, Imperial College London, Exhibition Road, London, United Kingdom.
    Krämer, Eva
    Umeå University, Faculty of Science and Technology, Department of Physics.
    Schulz, Leonard
    Institute of Geophysics and Extraterrestrial Physics, Technische Universität Braunschweig, Braunschweig, Germany.
    Palanca, Ines Terraza
    Faculty of Physics, University of Barcelona, Barcelona, Spain.
    Teubenbacher, Daniel
    Space Research Institute Graz, Austrian Academy of Sciences, Schmiedlstraße 6, Graz, Austria; Institute of Physics/IGAM, University of Graz, Graz, Austria.
    Baskevitch, Claire
    UMR8190 LATMOS (CNRS/Sorbonne Université), 4 place Jussieu, Paris, France; UMR8109, LESIA, Observatoire de Paris, université PSL, CNRS, Sorbonne Université, université de Paris, 5 place Jules Janssen, Meudon, France.
    Covella, Francesca
    Imperial College, London, United Kingdom.
    Cressa, Luca
    Advanced Instrumentation for Nano-Analytics (AINA), Luxembourg Institute of Science and Technology, 41 Rue du Brill, Belvaux, Luxembourg.
    Moreno, Juan Garrido
    Universitat Politècnica de Catalunya - BarcelonaTech (UPC), 11 Colom St., Catalonia, Terrassa, Spain.
    Gillmayr, Jana
    University of Graz, Rechbauerstraße 12, Graz, Austria.
    Hollowood, Joshua
    Department of Earth and Environmental Sciences, The University of Manchester, Manchester, United Kingdom.
    Huber, Kilian
    Advanced Instrumentation for Nano-Analytics (AINA), Luxembourg Institute of Science and Technology, 41 Rue du Brill, Belvaux, Luxembourg; Faculty of Science, Technology and Medicine, University of Luxembourg, 2 Avenue de l'Université, Esch-sur-Alzette, Luxembourg.
    Kutnohorsky, Viktoria
    Institute for Geophysics and Astrophysics, University of Graz, Graz, Austria.
    Lennerstrand, Sofia
    Luleå University of Technology, Luleå, Sweden.
    Malatinszky, Adel
    Space Research Laboratory, Centre for Energy Research, Konkoly-Thege Miklós út 29-33, Budapest, Hungary.
    Manzini, Davide
    Laboratoire de Physique des Plasmas (LPP), CNRS, École Polytechnique, Sorbonne Université, université Paris-Saclay, Observatoire de Paris, Palaiseau, France; Dipartimento di Fisica “Enrico Fermi”, Università di Pisa, Pisa, Italy.
    Maurer, Manuel
    University of Graz, Universitätsplatz 3, Graz, Austria.
    Nidelea, Daiana Maria Alessandra
    Politehnica University of Bucharest, Bucharest, Romania.
    Rigon, Luca
    Eidgenössische Technische Hochschule Zürich, Zürich, Switzerland.
    Sinjan, Jonas
    Max–Planck-Institut für Sonnensystemforschung, Justus-von-Liebig Weg 3, Göttingen, Germany.
    Suarez, Crisel
    Vanderbilt University, 12201 West End Ave, TN, Nashville, United States; The Center for Astrophysics, Harvard and Smithsonian, 60 Garden St, MA, Cambridge, United States.
    Viviano, Mirko
    Department of Electronics and Nanotechnology, School of Electrical Engineering, Aalto University, Maarintie 8, Espoo, Finland.
    Knutsen, Elise Wright
    LATMOS/IPSL, UVSQ Université Paris-Saclay, Sorbonne Universit, CNRS, Guyancourt, France.
    Magnetospheric Venus Space Explorers (MVSE) mission: a proposal for understanding the dynamics of induced magnetospheres2024In: Acta Astronautica, ISSN 0094-5765, E-ISSN 1879-2030, Vol. 221, p. 194-205Article in journal (Refereed)
    Abstract [en]

    Induced magnetospheres form around planetary bodies with atmospheres through the interaction of the solar wind with their ionosphere. Induced magnetospheres are highly dependent on the solar wind conditions and have only been studied with single spacecraft missions in the past. Without simultaneous measurements of solar wind variations and phenomena in the magnetosphere, establishing a link between both can only be done indirectly, using statistics over a large set of measurements. This gap in knowledge could be addressed by a multi-spacecraft plasma mission, optimized for studying global spatial and temporal variations in the magnetospheric system around Venus, which hosts the most prominent example of an induced magnetosphere in our solar system. The MVSE mission comprises four satellites, of which three are identical scientific spacecraft, carrying the same suite of instruments probing different regions of the induced magnetosphere and the solar wind simultaneously. The fourth spacecraft is the transfer vehicle which acts as a relay satellite for communications at Venus. In this way, changes in the solar wind conditions and extreme solar events can be observed, and their effects can be quantified as they propagate through the Venusian induced magnetosphere. Additionally, energy transfer in the Venusian induced magnetosphere can be investigated. The scientific payload includes instrumentation to measure the magnetic field, electric field, and ion–electron velocity distributions. This study presents the scientific motivation for the mission as well as requirements and the resulting mission design. Concretely, a mission timeline along with a complete spacecraft design, including mass, power, communication, propulsion and thermal budgets are given. This mission was initially conceived at the Alpbach Summer School 2022 and refined during a week-long study at ESA's Concurrent Design Facility in Redu, Belgium.

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  • 26.
    Alfredsson, Ammar
    Mälardalen University, School of Innovation, Design and Engineering.
    Utvärdering av förebyggande underhållsstrategi för elektriska flygplan2023Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This thesis focuses on the topic of preventive maintenance for electric aircraft and aims to examine its significance and implementation within the aviation industry. Electric aircraft have become increasingly popular as a sustainable alternative to conventional aircraft, making it crucial to develop effective maintenance strategies to ensure their reliability and performance.

    To achieve this objective, a comprehensive literature review of existing research and practices in the field of preventive maintenance for electric aircraft is conducted. The study identifies the key components and systems in an electric aircraft that require regular monitoring and maintenance, such as electric motors, batteries, power converters, and control systems.

    By analyzing the benefits of preventive maintenance, such as reduced downtime, increased component lifespan, and decreased maintenance costs, various methods, and techniques for implementing preventive maintenance for electric aircraft are presented. This includes the use of condition monitoring systems, sensors, and data-driven analysis to monitor and predict the health of components and anticipate any faults or deviations in advance.

    To explore the challenges of preventive maintenance for electric aircraft, aspects such as data management, cooling, and electromagnetic compatibility are also discussed. Furthermore, the need for training and skill development for maintenance personnel to effectively carry out preventive maintenance activities for electric aircraft is explored.

    By compiling and analyzing the available information, this thesis provides a comprehensive overview of preventive maintenance for electric aircraft and its significance in ensuring reliability, performance, and sustainability within the aviation industry. The findings can be valuable to airlines, maintenance organizations, and researchers interested in implementing effective maintenance strategies for electric aircraft and contributing to the continued development of sustainable aviation.

    The literature review showed that the use of preventive maintenance strategy for electric aircraft is well-founded and supported by research and experiences from various industries. The implementation of IoT and fault diagnostic techniques can enhance the maintenance process and increase the reliability of electric aircraft by identifying and addressing potential faults at an early stage. These findings provide valuable insights and guidelines for the aviation industry in developing and optimizing their maintenance strategies for electric aircraft.

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  • 27.
    Alho, Markku
    et al.
    Department of Electronics and Nanoengineering, School of Electrical Engineering, Aalto University, Aalto, Finland.
    Wedlund, Cyril Simon
    Department of Physics, University of Oslo, Oslo, Norway.
    Nilsson, Hans
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology. Swedish Institute of Space Physics, Kiruna, Sweden.
    Kallio, Esa
    Department of Electronics and Nanoengineering, School of Electrical Engineering, Aalto University, Aalto, Finland.
    Jarvinen, R.
    School of Electrical Engineering, Aalto University, Aalto, Finland. Finnish Meteorological Institute, Helsinki, Finland.
    Pulkkinen, T.I
    School of Electrical Engineering, Aalto University, Aalto, Finland. Department of Climate and Space Sciences and Engineering, University of Michigan, Ann Arbor, MI,USA.
    Hybrid modeling of cometary plasma environments: II. Remote-sensing of a cometary bow shock2019In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 630, article id A45Article in journal (Refereed)
    Abstract [en]

    Context. The ESA Rosetta probe has not seen direct evidence of a fully formed bow shock at comet 67P/Churyumov–Gerasimenko (67P). Ion spectrometer measurements of cometary pickup ions measured in the vicinity of the nucleus of 67P are available and may contain signatures of the large-scale plasma environment.

    Aims. The aim is to investigate the possibility of using pickup ion signatures to infer the existence or nonexistence of a bow shock-like structure and possibly other large-scale plasma environment features.

    Methods. A numerical plasma model in the hybrid plasma description was used to model the plasma environment of a comet. Simulated pickup ion spectra were generated for different interplanetary magnetic field conditions. The results were interpreted through test particle tracing in the hybrid simulation solutions.

    Results. Features of the observed pickup ion energy spectrum were reproduced, and the model was used to interpret the observation to be consistent with a shock-like structure. We identify (1) a spectral break related to the bow shock, (2) a mechanism for generating the spectral break, and (3) a dependency of the energy of the spectral break on the interplanetary magnetic field magnitude and bow shock standoff distance.

  • 28.
    Ali, Ahsan
    Luleå University of Technology, Department of Engineering Sciences and Mathematics.
    Effect of temperature on early stage adhesion during TiAlN sliding against Inconel 718 and Stainless steel 316L: High temperature tribology2023Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    High-performance materials such as stainless steels and nickel based super alloys are widely used in demanding applications where high mechanical and thermal properties are required. The applications of super alloys are mainly found in jet engines, power plants and gas turbines demanding high fatigue strength, corrosion and oxidation resistance as well as wear resistant properties. In order to use them, they go through various machining processes such as milling, turning, cutting, polishing etc. until the final product is achieved. Modern manufacturing industries employs various machining tools and technologies to improve the machining process of heat resistant super alloys. However, there are still challenges which needs to be addressed. Among them, adhesive wear of the machining tools is one of the main wear mechanism during the tribological interaction of tool and workpiece, preventing them to achieve the desired quality and surface finish of the end product. Moreover, it damages the tool reducing its lifecycle and in return, increasing the production cost. Among the cutting tools tungsten carbide (WC/Co) tools coated with TiAlN coating due to their good high temperature performance are extensively used. Nonetheless, these coatings still face issue like adhesive wear, abrasion, oxidation at higher temperature damaging the tools and subsequent machining. Therefore, it is imperative to understand the initiation mechanism of adhesive wear during the tribological interaction of super alloys and coated cutting tool material.

    In this research work, the tribological response of two coatings deposited by physical vapour deposition (PVD), having the composition Ti60Al40N and Ti40Al60N have been studied against two super alloys material, i.e. Inconel 718 and stainless steel 316L. A high temperature SRV (Schwingung (Oscillating), Reibung (Friction), Verschleiß (Wear)) reciprocation friction and wear test set up was employed to investigate the friction behaviour, wear rate and dominant wear mechanisms. 

    For Ti60Al40N coating, the experimental results revealed that generally, friction increases in case of sliding against Inconel 718 up to 400 °C and drops at 760 °C. A high wear volume at room temperature and a decrease to a minimum at 760 °C has been observed for Inconel 718. On the other side, Stainless steel 316L (SS 316L) faces a continuous rise in friction coefficient with highest value at 760 °C during sliding against Ti60Al40N coating. Wear is highest at 400 °C for SS 316L pin. The worn surfaces shows that both workpiece materials experience increase in material transfer due to adhesive wear with rise in temperature. At 400 °C, adhesion is the primary wear mechanism for both workpiece materials. A further rise in temperature to 760 °C promotes the adhesive wear through oxides formation on both material surfaces. 

    Similarly, Ti40Al60N coating shows the same friction behaviour with change in average steady state friction values for both material of Inconel 718 and SS 316L. Both workpiece materials responds in a similar way to wear volume loss, i.e. lowest at room temperature and highest at 760 °C. For Inconel 718, transfer of coating constituents on to the Inconel 718 pin surface was detected and associated with coating rupture and peeling, exacerbating with rise in temperature. Adhesion, abrasion, and oxidation are primary wear mechanisms at 400 °C and 760 °C. For SS 316L, coating transfer only happen at 400 °C. No damage of coating at 40 °C, a complete damage at 400 °C, and formation of dense porous oxides layers at 760 °C have been noticed. At 400 °C, adhesion, abrasion, and chipping while at 760 °C, adhesion, three body abrasion, ploughing and oxidation are the main wear mechanisms.

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  • 29.
    Ali, Saif
    Umeå University, Faculty of Science and Technology, Department of Computing Science.
    Optimization-Based Carefree Clearance: An Optimization-Based Approach to Identifying Worst-Case Manoeuvres for Fighter Aircraft2024Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The development of advanced Flight Control Systems (FCSs) is continuously progressing at a rapid pace. Originally consisting of purely mechanical functions for the deflection of control surfaces, the transition to Fly-By-Wire technology allowed for the inclusion of highly automatized algorithms within the control system. However, for such complex systems follows a rigorous validation and verification process to ensure safe and reliable flight. In the clearance of its control laws, the FCS must be tested for all possible uncertainties and manoeuvres, resulting in a lengthy and costly process, not least for fighter aircraft with the additional requirement of carefree handling. The demand for efficient and comprehensive tools drives the effort of this thesis, which explores the use of optimization, specifically multi-modal Genetic Algorithms for identification of diverse worst-case manoeuvres. Against the traditional methodology which uses gridding of flight conditions and a set of predefined manoeuvres for assessing clearance, the optimization-based methods were consistently able to find manoeuvres resulting in more problematic outcomes.

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  • 30.
    Ali, Sheikh Nawaz
    et al.
    Birbal Sahni Institute of Palaeobotany, Lucknow.
    Shekhar, Mayank
    Birbal Sahni Institute of Palaeobotany, Lucknow.
    (Pandey, Pratima
    Indian Institute of Technology, Bombay.
    Bhardwaj, Anshuman
    Snow and Avalanche Study Establishment, Defence Research and Development Organization (DRDO), Him Parisar, Sector-37A, Chandigarh.
    Singh, Shaktiman
    Department of Environmental Science, School of Basic Sciences and Research, Sharda University, Greater Noida.
    Indian Himalayan capacity and adaptation programme: capacity-building in Himalayan glaciology2014In: Current Science, ISSN 0011-3891, Vol. 106, no 3, p. 346-Article in journal (Other academic)
  • 31.
    Allam, Sabry
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Åbom, Mats
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Advanced experimental procedure for in-duct aero-acoustics2006In: 13th International Congress on Sound and Vibration 2006, ICSV 2006, 2006, p. 1185-1192Conference paper (Refereed)
    Abstract [en]

    The purpose of this paper is to present a method for characterization of in-duct aero-acoustic sources that can be described as active acoustic two-ports. The method is applied to investigate the sound produced from an orifice plate. The motivation is to obtain better data for the development of improved prediction methods for noise from flow singularities, e.g., in HVAC systems on aircrafts. Most of the earlier works fall into two categories; papers modeling the scattering of acoustic waves and papers modeling the sound generation. Concerning the scattering it is possible to obtain estimates of the low frequency behavior from linear perturbations of the steady state equations for the flow. Concerning the sound generation most of the presented work is experimental and follows a paper by Nelson&Morfey, which present a scaling law procedure for the in-duct sound power based on a dipole model of the source. One limitation with the earlier works is that the sound power only was measured on the downstream side. Also data was only obtained in 1/3-octave bands, by measuring the sound radiated from an open duct termination. Assuming plane waves and linear acoustics the flow duct singularity can be completely modeled as an active 2-port. The experimental determination of its properties is done in a two steps procedure. In the first step the passive data, i.e., the scattering matrix S, is determined using external (independent) sources. In the second step the S matrix is used and the source vector is determined by testing the system with known acoustic terminations.

  • 32.
    Alonso Rancurel, Belén
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Material Science.
    Investigation of high temperature stability of additive manufactured austenitic stainless steels for space applications2023Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Additive manufacturing (AM) techniques are being studied for their application in the aerospace industry. Numerous benefits come from the already in shape final piece, which needs reduced amount of prime material for its production and can have its shape numerically optimized for weight reduction. Austenitic stainless steels (AuSS) are widely used in aerospace and their manufacturing through AM is a popular research topic in order to accelerate their effective incorporation in air-crafts and spaceships. The special microstructures of AM has been observed with characterization techniques. The present work studies the high temperature stability of three AuSS (316L, MOD-316 and 21-6-9) considering two approaches; surface corrosion and microstructure evolution.

    First, for high temperature corrosion, thermogravimetric analysis has been performed from 850°C to 1150°C. From the results, kinetic analysis were performed and the activation energy was extracted from Arrhenius fits. Two mechanism were found for alloy 316L (first 435.41 kJ/mol and second 593.24 kJ/mol) and MOD-316 (first 740.01 kJ/mol and second 495.58 kJ/mol). Further SEM observations on the scales have shown Ni diffusion through the chromia scale in MOD-316 alloy, which could explain the higher oxidation rates at 1150°C. Alloy 21-6-9 has the best passivation behaviour with an activation energy of 190.47 kJ/mol.

    Secondly, long heat treatment (HT) at 725°C in air atmosphere has been performed, for 24 and 240h. Samples were initially as-built or annealed (900°C for 1h), to compare the effect of the HT on the microstructure evolution and precipitates formation. LOM observation showed preferable nucleation in grain boundaries (GB), an increment of the number of precipitates and a growth towards elongated shapes following GB with increased time. It was also observed a reduction in precipitates number with the annealing HT for all the alloys. XRD, SEM and EDS analysis has been carried out to identify the structure and composition of the precipitates. Various chromium, tungsten, copper, molybdenum and niobium carbides and oxides have been found in MOD-316. Higher porosity is observed in 21-6-9, that presented mainly chromium oxides, carbides and nitrides in GB and surrounding the AM defects.

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  • 33.
    Alshahrani, Ali
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Vehicle Engineering and Solid Mechanics, Flight Dynamics.
    Analysis and Initial Optimization of The Propeller Design for Small, Hybrid-Electric Propeller Aircraft2020Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis focuses on the optimization of the electric aircraft propeller in order to increaseflight performance. Electric aircraft have limited energy, particularly the electricmotor torque compared to the fuel engine torque. For that, redesign of the propeller forelectric aircraft is important in order to improve the propeller efficiency. The airplanepropeller theory for Glauert is selected as a design method and incorporated with Brattimprovements of the theory. Glauert theory is a combination of the axial momentum andblade element theory. Pipistrel Alpha Electro airplane specifications have been chosen asa model for the design method. Utilization of variable pitch propeller and the influence ofnumber of blades has been investigated. The obtained design results show that the variablepitch propellers at cruise speed and altitude 3000 m reducing the power consumptionby 0.14 kWh and increase the propeller efficiency by 0.4% compared to the fixed pitchpropeller. Variable pitch propeller improvement was pretty good for electric aircraft. Theoptimum blade number for the design specifications is 3 blades.

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  • 34.
    Amadori, Kristian
    et al.
    Linköping University, Department of Management and Engineering, Machine Design. Linköping University, The Institute of Technology.
    Melin, Tomas
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Staack, Ingo
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Krus, Petter
    Linköping University, Department of Management and Engineering, Fluid and Mechatronic Systems. Linköping University, The Institute of Technology.
    Multidisciplinary Optimization of Wing Structure Using Parametric Models2013Conference paper (Other academic)
    Abstract [en]

    Aircraft design is an inherently multidisciplinary activity that requires integrating different models and tools to reach a well-balanced and optimized product. At Linköping University a design framework is being developed to support the initial design space exploration and the conceptual design phase. Main characteristics of the framework are its flexible database in XML format, together with close integration of automated CAD and other tools, which allows the developed geometry to be directly used in the subsequent preliminary design phase. In particular, the aim of the proposed work is to test the framework by designing, optimizing and studying a transport aircraft wing with respect to aerodynamic, geometry, structural and accessability constraints. The project will provide an initial assessment of the capability of the framework, both in terms of processing speed and accuracy of the results.

  • 35.
    Ambre, Rombaut
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Flight Dynamics.
    Landing the Propellant Stage of a launcher2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    To reduce the cost of launch, several aerospace companies are exploring the possibility of partly reusable launchers. In order to be reusable with minimum refurbishment cost the reusable part of the launcher has to suffer little damage and land in optimal conditions. In this paper, a guidance algorithm to achieve the return of the reusable vehicle on ground through a vertical landing is described. Different mission scenarios are taken into account and the performance of the guidance algorithm is assessed using a 6 Degrees Of Freedom simulator.

  • 36.
    Amin, Rebin
    Mälardalen University, School of Innovation, Design and Engineering.
    Tool for Risk Evaluation2017Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
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  • 37.
    Amini, Kasra
    et al.
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences (SCI), Engineering Mechanics.
    Janabadi, Ehsan Dehghani
    Univ Art, Fac Architecture & Urban Planning, Dept Architectural Technol, Tehran, Iran..
    Fayaz, Rima
    Univ Art, Fac Architecture & Urban Planning, Dept Architectural Technol, Tehran, Iran..
    Lighting and illumination investigation of long-term residence on Mars for the case of a set of designed Martian Habitat Units (MHUs)2022In: Acta Astronautica, ISSN 0094-5765, E-ISSN 1879-2030, Vol. 192, p. 210-232Article in journal (Refereed)
    Abstract [en]

    Addressing the subject matter of human missions on Mars, the Martian Habitat Units (MHUs) are presented as a comprehensive solution. MHUs are designed in clusters of 10 units, each capable of serving as long-term habitats for 9 scientific crew members. The life-style requirements of the units are targeted at an imitation of cultural thriving life we all know of, and not a mere survival-type shelter expecting the first people to step foot on Mars. One aspect of many challenging issues to be addressed in such complex settings is the lighting and illuminance condition of the said habitats, which in the context of Mars, and generally deep space missions being far from the sun will certainly lead to an arduous task. To check the validity of the argument and assess the extent to which the natural light level available on the surface of Mars will be sufficient for the daily requirements of the crew and mission in terms of illuminance, the current manuscript presents thorough and detailed simulations and analyses on the availability evaluation of natural lighting in the site location of MHUs, namely Valles Marineris, Melas Chasma. In this paper solar irradiation parameters on Mars are calculated based on the previous research which resulted in global, direct and diffuse irradiance at 12 different Martian solar times. The simulations are distributed over the Martian year and its day-time, and for two extreme orientations of MHUs in their circular surrounding cluster, namely East/West and South/North units. The distribution of illuminance for each case, and trend comparison studies are then accompanied by numerical values and analyses on the percentage to which the natural lighting conditions on Mars have been shown to be sufficient as a fraction of the whole lighting load of the habitats, which is to be compensated using artificial sources. The corresponding values are shown to fall well in the range of 35-45% of the total lighting loads. Also, as the results of the simulations show, due to the consistency of the glazed parts of the designed facade through all exterior surface of the MHU, natural lighting sufficiency percentage does not show a significant difference between two simulated orientations. This fact further approves the circular orientation premise of the MHUs in their cluster.

  • 38.
    Amini, Kasra
    et al.
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences (SCI), Engineering Mechanics. Univ Stuttgart, Inst Aerosp Thermodynam ITLR, Stuttgart, Germany..
    Moradi, Mojgan
    Univ Art, Fac Architecture & Urban Planning, Dept Architectural Technol, Tehran, Iran..
    Teymoori, Peyman Ebadi Belfeh
    Univ Art, Fac Architecture & Urban Planning, Dept Architectural Technol, Tehran, Iran..
    Vossoughi, Bahareh
    Rhein Westfal TH Aachen, Fac Mech Engn, Aachen, Germany.;Rhein Westfal TH Aachen, Inst Combust Engines Verbrennungskraftmaschinen, Aachen, Germany..
    Janabadi, Ehsan Dehghani
    Univ Art, Fac Architecture & Urban Planning, Dept Architectural Technol, Tehran, Iran..
    Fayaz, Rima
    Univ Art, Fac Architecture & Urban Planning, Dept Architectural Technol, Tehran, Iran..
    Design of a set of habitat units and the corresponding surrounding cluster for long-term scientific missions in the pre-terraforming era on mars2022In: Icarus, ISSN 0019-1035, E-ISSN 1090-2643, Vol. 385, p. 115119-, article id 115119Article in journal (Refereed)
    Abstract [en]

    We are living in a point in the history of science and technology, where space travel for research and settlement is inevitable. As the utmost crucial technology pieces for leaving Earth and travelling into the cosmos is being established one after another, it is just a matter of decades, until it all gets integrated together, solving the engineering problems ahead of the way and being able to step on the planets and moons of the solar system. In this quest, as has been the case for most of the technological advancements so far, there ought to be mind experiments, in which one skips one step, assumes the availability of responses to the skipped-over step, and searches for the solution to the questions of the next level. This way, by getting passed the first, i.e. current step, the solution to the next one is already available. The current manuscript is addressing this very 'next step', on the long path to eventually colonize Mars and inhabit it for long-term research-based missions; let it be for terraforming, or other agenda to be defined by the research strategists, then. And as mentioned earlier, the current step; being setting foot on Mars, is well-deservedly taken for granted, as is to come forth undoubtedly. Having that realized, we might find ourselves faced by the engineering complexities of surviving and thriving on Mars, which is the subject matter of the current research, from the aspect point of space technological and architectural design. The design procedure beginning from setting the philosophy of design upon the concerns of sustaining in the hostile environment of Mars, to the stepwise emergence of the final design of a cluster of Martian Habitat Units (MHUs) considering the high-criteria of the case, is the subject matter covered in this manuscript.

  • 39.
    Amini, Kasra
    et al.
    KTH, School of Engineering Sciences (SCI), Engineering Mechanics, Fluid Mechanics and Engineering Acoustics.
    Moradi, Mojgan
    Department of Architectural Technology, Faculty of Architecture and Urban Planning, University of Art, Tehran, Iran.
    Vossoughi, Bahareh
    Faculty of Mechanical Engineering, RWTH Aachen University, Aachen, Germany.
    Janabadi, Ehsan Dehghani
    Department of Architectural Technology, Faculty of Architecture and Urban Planning, University of Art, Tehran, Iran.
    Space-technological and architectural methodology and process towards design of long-term habitats for scientific human missions on mars2023In: MethodsX, ISSN 1258-780X, E-ISSN 2215-0161, Vol. 11, article id 102270Article in journal (Refereed)
    Abstract [en]

    Centered on the core idea of long duration habitat design for research crew on Mars, the Martian Habitat Units (MHUs) are designed as a cluster of 10 units each with the maximum capacity of 9 crew members to live and carry on with the local challenges of scientific and exploratory life, while enjoying their lives as intellectual, social individuals in the harsh environment of Mars for durations in the order of magnitude of several years. This approach to the concept of a living environment in sharp contradiction to that of a shelter with the minimal capabilities to meet the requirements of terrestrial life to the point of survival, has led the outcoming design to be a fulfilling environment for the inhabitants of the units to evolve and thrive culturally, while being on a years-long mission. This manuscript provides detailed insight on the lessons learned of the aforementioned comprehensive design attempt with, but not limited to, the following core concerns: • The initial stand-point of such a design procedure relies on an ever increasing and comprehensive list of concerns, be it classically discussed in the literature and predictable, or unforeseen on the face of it, but to be prevented anyhow. The manuscript discusses the most crucial ones of such criteria/concerns. • The infamous saying of “Whatever that can go wrong, will go wrong” demands a rather complex level of redundancies in all layers of the design and the thought procedure behind its all aspects. The manuscript addresses the adequate steps towards its realization. • Modularity in all layers of the design plays a key role in reducing construction, maintenance, and installation costs, as for any deep space mission the mentioned expenses are astronomically high themselves. The manuscript presents our solution for geometric modularity of the design.

  • 40. Amoignon, Olivier
    et al.
    Pralits, Jan O.
    Hanifi, Ardeshir
    Swedish Defence Research Agency.
    Berggren, M.
    Henningson, Dan S.
    KTH, School of Engineering Sciences (SCI), Mechanics, Stability, Transition and Control.
    Shape optimization for delay of laminar-turbulent transition2006In: AIAA Journal, ISSN 0001-1452, E-ISSN 1533-385X, Vol. 44, no 5, p. 1009-1024Article in journal (Refereed)
    Abstract [en]

    A method using gradient-based optimization is introduced for the design of wing profiles with the aim of natural laminar How, as well as minimum wave drag. The Euler equations of gasdynamics, the laminar boundary-layer equations for compressible flows on infinite swept wings, and the linear parabolized stability equations (PSE) are solved to analyze the evolution of convectively unstable disturbances. Laminar-turbulent transition is assumed to be delayed by minimizing a measure of the disturbance kinetic energy of a chosen disturbance, which is computed using the PSE. The shape gradients of the disturbance kinetic energy are computed based on the solutions of the adjoints of the state equations just named. Numerical tests are carried out to optimize the RAE 2822 airfoil with the aim to delay simultaneously the transition, reduce the pressure drag coefficient, and maintain the coefficients of lift and pitch moments. Constraints are also applied on the geometry. Results show a reduction of the total amplification of a large number of disturbances, which is assumed to represent a delay of the transition in the boundary layer. Because delay of the transition implies reduction of the viscous drag, the present method enables shape optimization to perform viscous drag reduction.

  • 41.
    Amro, Adib
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Öberg Sjöstrand, Billy
    För- och nackdelar med att förlänga/förkorta flygets underhållsintervaller2017Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Abstract

    Aircraft maintenance within the aviation industry is an essential part as the purpose is to maintain the aircrafts built-in security and reliability levels. Aircraft require approved and straightforward maintenance to ensure safe operation and airworthiness. The maintenance program's intention is to ensure that a function operates properly despite an uncertain environment. During flights, aircraft are exposed to a large number of loads, which causes components and parts to be affected negatively. Because of this, a maintenance program is presented, the program tries to constantly detect and correct any potential errors before a functional error occurs.

    This degree project is about finding out about the pros and cons of extending or shortening the maintenance interval within the aircraft maintenance program. In addition, the purpose is to draw conclusions about how airline, aircraft turbine performance and age are related to extension or shortening of this maintenance interval. The dissertation was written at the Academy of Innovation, Design and Technology at Mälardalens högskola, Västerås.

    The work process was carried out in several steps. The first step was to deepen the knowledge within the field and understand the maintenance program. This was done through literature studies and information gathering on the subject. The second step was to analyze and process the general information and answers from the interview questions. The work included the advantages and disadvantages caused by extension or shortening of maintenance intervals without affecting the reliability that maintenance requirements ensure. 

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  • 42.
    Anantha Raman, Deepa
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Thermal environment and design considerations of the Foresail-2 satellite mission2023Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The thermal design of small satellite missions is critical for ensuring the performance and longevity of onboard instruments. This thesis focuses on the thermal design of Foresail-2, a 6U CubeSat mission to Geostationary Transfer Orbit (GTO), specifically addressing the thermal challenges associated with the magnetometer located at the end of a long boom featured on the satellite.

    The objective of this research is to estimate the orbital loads, study its effects and develop an effective thermal control strategy to maintain the frame, boom and magnetometer temperature within an optimal operational range throughout the mission duration. A steady state thermal analysis is conducted to evaluate the effects of the GTO environment on the satellite structure under different operational scenarios and design conditions. To achieve the desired thermal control, several potential regulation strategies are investigated, including passive thermal coatings, insulation materials, and active cooling methods.

    Furthermore, thermal simulations are performed to predict the temperature profiles and gradients within the boom and magnetometer assembly, enabling the identification of potential hotspots or areas prone to thermal stress using ANSYS software package. These findings contribute to the implementation of thermal design modifications and the optimization of the configuration of the boom and magnetometer to enhance thermal performance.

    The results of this thesis contribute to the development of a robust thermal design for Foresail-2 mission satellite. Moreover, the methodologies and insights gained from this research can be extended to other CubeSat missions with similar thermal requirements and constraints.

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  • 43.
    Andersen, Torben
    et al.
    Lunds universitet.
    Enmark, Anita
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Integrated Modeling of Telescopes2011Book (Other academic)
  • 44.
    Andersen, Torben
    et al.
    Lund Observatory (Sweden) .
    Owner-Petersen, Mette
    Lund Observatory (Sweden) .
    Enmark, Anita
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Image-based wavefront sensing for astronomy using neural networks2020In: Journal of Astronomical Telescopes, Instruments, and Systems, ISSN 2329-4124, Vol. 6, no 3, article id 034002Article in journal (Refereed)
    Abstract [en]

    Motivated by the potential of non-diffraction limited, real-time computational image sharpening with neu7 ral networks in astronomical telescopes, we have studied wavefront sensing with convolutional neural networks basedon a pair of in-focus and out-of-focus point spread functions. By simulation, we generated a large dataset for trainingand validation of neural networks, and trained several networks to estimate Zernike polynomial approximations forthe incoming wavefront. We included the effect of noise, guide star magnitude, blurring by wide band imagining, andbit depth. We conclude that the “ResNet” works well for our purpose, with a wavefront RMS error of 130 nm forr0 = 0.3 m, guide star magnitudes 4–8, and inference time of 8 ms. It can also be applied for closed-loop operation inan adaptive optics system. We also studied the possible use of a Kalman filter or a recurrent neural network and foundthat they were not beneficial to performance of our wavefront sensor

  • 45.
    Andersson, Daniel
    University West, Department of Engineering Science.
    The performance of an iced aircraft wing2011Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The goal of this thesis work has been to develop and manufacture an ice layer which was to be mounted on the tip of a scaled down wing model. The iced wing should be tested in a wind tunnel and aerodynamic comparisons should be made to the same wing without ice.The development of the ice was carried out as a modified product development process. The main differences are that there is no costumer and that the actual shape and functions of the product are more or less predetermined. The challenge was to find the best way to create the ice layer and how to mount it to the wing without damaging it or covering any pressure sensors. Product development methods such as pros and cons lists and prototypes were used to solve problems before printing the plastic ice layer in a rapid prototyping machine.Wind tunnel experiments were then conducted on the wing with and without the manufactured ice. Raw data from the wind tunnel were processed and lift and drag coefficients were calculated using mathematical equations. Finally, conclusions were drawn by comparing the results from the wind tunnel tests with theory, other works as well as CFD simulations.The ice layer was successfully manufactured and it met the target specifications. The aerodynamic performance of an iced aircraft wing proved to be considerably worse compared to a blank wing. The maximum achievable lift force decreased by 22% and an increased drag force will require more thrust from the airplane.

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    The performance of an iced aircraft wing
  • 46.
    Andersson, Erik
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Numerical Approach to the Design and Optimisation of a Bi-Propellant Pintle Injector2022Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Rocket propulsion is of vital importance for space travel. New innovations are continuously developed in order to facilitate the demand of the rapidly evolving space sector. Recently a focus on reusable rockets has appeared due to the economical and environmental benefits they bring. When designing reusable launch vehicles the propellant injector becomes very important since it is a critical component when throttleabilty is desired. Which is a key element of landable rockets. Selecting an appropriate injector type therefore becomes crucial, a common injector type used for throttleable rockets is the pintle injector.

    Unfortunately the design process of the pintle injector is complicated due to the large amount of variables that must be determined. This thesis aims to solve this problem by developing a numerical method to design and optimise a pintle injector and then produce a preliminary design.

    The numerical method developed in this thesis is used to produce a preliminary design of a pintle injector designed to utilise a combination of liquid oxygen and gaseous methane, theoretically capable of a max thrust of 1000N and a throttleabilty of 5 to 1. The design had a focus on optimising the performance of the parameters sauter mean diameter, vaporisation distance and spray angle for the injector. The resulting injector showcases great performance and is deemed to show a successful preliminary design. Which shows that the numerical design and optimisation process that was developed also was successful.

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  • 47.
    Andersson, Erik
    Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Space Technology.
    Preliminary design of a small-scale liquid-propellant rocket engine testing platform2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Propulsion system testing before mission operation is a fundamental requirement in any project. For both industrial and commercial entities within the space industry, complete system integration into a static test platform for functional and performance testing is an integral step in the system development process. Such a platform - if designed to be relatively safe, uncomplicated and reliable - can be an important tool within academia as well, giving researchers and students a possibility for practical learning and propulsion technology research.

    In this thesis, a preliminary design for a liquid-propellant rocket engine testing platform to be used primarily for academical purposes is developed. Included in the presented design is a bi-propellant Chemical Propulsion system, gas pressure fed with Gaseous Nitrogen and using Gaseous Oxygen as oxidiser and a 70 % concentrated ethanol-water mixture as fuel. The propellant assembly contains all necessary components for operating the system and performing combustion tests with it, including various types of valves, tanks and sensors. An estimation of the total preliminary cost of selected components is presented as well. Also part of the developed platform design is a small thrust chamber made of copper, water-cooled and theoretically capable of delivering 1000 N of thrust using the selected propellants.

    A list of operations to be performed before, during and after a complete combustion test is presented at the end of the document, together with a preliminary design of a Digital Control and Instrumentation System software. Due to time limitations, the software could not be implemented in a development program nor tested with simulated parameters as part of this thesis project.

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  • 48.
    Andersson, Erik
    et al.
    Halmstad University, School of Business and Engineering (SET).
    Bengtsson, Per-Johan
    Halmstad University, School of Business and Engineering (SET).
    Dark Ages Lunar Interferometer (DALI): Deployment-Rover - Mobility System2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This thesis is issued in collaboration with the Jet Propulsion Laboratory (JPL) in Pasadena, California. JPL's primary function is the construction and operation of robotic planetary spacecraft. At the time being JPL has 22 spacecraft and 10 instruments conducting active missions.

    The "Dark Ages" represent the last frontier in cosmology, the era between the genesis of the cosmic microwave background (CMB) and the formation of the first stars. During the Dark Ages, when the Universe was unlit by any star, the only detectable signal is likely to be that from neutral hydrogen (HI).

    The HI absorption occurs in dark matter-dominated overdensities, locations that will later become the birthplaces of the first stars. Tracing this evolution will provide crucial insights into the properties of dark matter and potentially reveal aspects of cosmic inflation. This could be accomplished using a radio telescope located on the far side of the Moon, the only site in the solar system shielded from human-generated interference and, at night, from solar radio emissions.

    Our objective has been the development of the concept of an autonomous rover that would be capable of deploying a large number of low frequency radio antennas on the lunar surface. This is an enabling task for the eventual creation of a radio telescope.

    The project at Halmstad University was divided into three sub-projects, where our area of responsibility has been the development of a concept of the rover's mobility system.

    The result of the project is the concept of a "Rocker-Bogie" suspension system, created in a 3D-environment. A concept which underwent a series of digital analyses and simulations to ensure the compliance with required specifications.

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    Dark Ages Lunar Interferometer (DALI): Deployment-Rover - Mobility System
  • 49.
    Andersson, Fredrik
    et al.
    Mälardalen University, School of Innovation, Design and Engineering.
    Karlsson, Rikard
    Mälardalen University, School of Innovation, Design and Engineering.
    HIGHLY CRITICAL GRAPHICS GENERATION ON A SYSTEM-ON-CHIP PLATFORM2022Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The critical applications domain stands today at the brink of a great divide. On one side, the deterministic and safe operational prerequisite of the system. On the other, an ever increasing demand for computational power and miniaturization. In some cases, the welfare of people hinge in the balance of these attributes. It is therefore vital that these system undergo strict and rigorous development and testing. Development has evolved a great deal with regards to computational power and miniaturization. So too has the development of deterministic and safely operational systems. However the combination of these two are a complex matter. A light in the dark might be seen in the Commercial Off The Shelf System-on-Chip, which offers great computational power in relation to its volume. This thesis’s objective is to investigate potential fault-detection methods applicable on commercial System-on-Chip. To determine applicability, multiple implementations have been made and tested. Results from which suggest that fault detection methods implemented on field programmable gate array are highly effective. However, not all worst case execution time analysis conducted in this thesis are deemed a success. A common-mode analysis is conducted which indicated that functions already present on the System-on-Chip, before implementation, negated the effect of common-cause failures under scrutiny in the analysis. The majority of the data gathered from state of the art, implementations and common-mode analysis conducted, indicate that commercial off the shelf multi-processor System-on-Chip platforms have great potential in safety critical systems. 

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    Andersson Granberg, Tobias
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Polishchuk, Tatiana
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Polishchuk, Valentin
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Schmidt, Christiane
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    A framework for integrated terminal airspace design2019In: Aeronautical Journal, ISSN 0001-9240, Vol. 123, no 1263, p. 567-585Article in journal (Refereed)
    Abstract [en]

    Route planning and airspace sectorisation are two central tasks in air traffic management. Traditionally, the routing and sectorisation problems were considered separately, with aircraft trajectories serving as input to the sectorisation problem and, reciprocally, sectors being part of the input to the path finding algorithms. In this paper we propose a simultaneous design of routes and sectors for a transition airspace. We compare two approaches for this integrated design: one based on mixed integer programming, and one Voronoi-based model that separates potential "hotspots" of controller activity resulting from the terminal routes. We apply our two approaches to the design of Stockholm Terminal Maneuvering Area.

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