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  • 301.
    Metaferia, Wondwosen
    et al.
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Halvledarmaterial, HMA.
    Tommila, J.
    Junesand, Carl
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Halvledarmaterial, HMA.
    Kataria, Himanshu
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Halvledarmaterial, HMA.
    Hu, Chen
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Halvledarmaterial, HMA.
    Guina, M.
    Niemi, T.
    Lourdudoss, Sebastian
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Materialfysik, Halvledarmaterial, HMA.
    Selective area heteroepitaxy through nanoimprint lithography for large area InP on Si2012Ingår i: Physica Status Solidi. C, Current topics in solid state physics, ISSN 1610-1634, E-ISSN 1610-1642, Vol. 9, nr 7, s. 1610-1613Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The use of nanoimprint lithography, a low cost and time saving alternative to E-beam lithography, for growing heteroepitaxial indium phosphide layer on silicon is demonstrated. Two types of patterns on 500 nm and 200 nm thick silicon dioxide mask either on InP substrate or InP seed layer on silicon were generated by UV nanoimprint lithography: (i) circular openings of diameter 150 nm and 200 nm and (ii) line openings of width ranging from 200 nm to 500 nm. Selective area growth and epitaxial lateral overgrowth of InP were conducted on these patterns in a low pressure hydride vapour phase epitaxy reactor. The epitaxial layers obtained were characterized by atomic force microscopy, scanning electron microscopy and micro photoluminescence. The growth from the circular openings on InP substrate and InP (seed) on Si substrate is extremely selective with similar growth morphology. The final shape has an octahedral flat top pyramid type geometry. These can be used as templates for growing InP nanostructures on silicon. The grown InP layers from the line openings on InP substrates are ∌ 2.5 Όm thick with root mean square surface roughness as low as 2 nm. Completely coalesced layer of InP over an area of 1.5 mm x 1.5 mm was obtained.The room temperature photoluminescence intensity from InP layers on InP substrate is 55% of that of homoepitaxial InP layer. The decrease in PL intensity with respect to that of the homoepitaxial layer is probably due to defects associated with stacking faults caused by surface roughness of the mask surface. Thus in this study, we have demonstrated that growth of heteroepitaxial InP both homogeneously and selectively on the large area of silicon can be achieved. This opens up the feasibility of growing InP on large area silicon for several photonic applications.

  • 302.
    Midander, Klara
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Metal release from powder particles in synthetic biological media2006Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Humans are exposed to metals and metal-containing materials daily, either conscious, e.g. using metal tools or objects, or unconscious, e.g. during exposure to airborne metal-, and metal-containing particles. The diffuse dispersion of metals from different sources in the society, and the concern related to its potential risk for adverse effects on humans have gained an increased public and governmental attention both on a national and international level. In this context, the knowledge on metal release from metallic objects or metal-containing particles is essential for health risk assessment.

    This thesis focuses on the study of metal release from powder particles of stainless steel and Cu-based materials exposed to synthetic body fluids mainly for simulating lung-like environments. The study comprises: i) development of a suitable experimental method for metal release studies of micron sized particles, ii) metal release data of individual alloy constituents from stainless steel powder particles of different particle sizes, and iii) Cu release from different Cu-based powder particles. In addition, the influence of chemical and physical properties of metallic particles and the test media are investigated. Selected results from Ni powder particles exposed to artificial sweat are presented for comparison. The outcome of this research is summarized through ten questions that are formulated to improve the general understanding of corrosion-induced metal release from metallic particles from a health risk perspective.

    A robust, reproducible, fairly simple, and straightforward experimental procedure was elaborated for metal release studies on particles of micron or submicron size. Results in terms of metal release rates show, for stainless steel powder particles, generally very low metal release rates due to a protective surface oxide film, and Fe preferentially released compared to Cr and Ni. Metal release rates are time-dependent for both stainless steel powder particles and the different Cu-containing powders investigated. The release of Cu from the Cu-containing particles depends on the chemical and compositional properties of the Cu-based material, being either corrosion-induced or chemically dissolved. Moreover, the test medium also influences the metal release process. The metal release rate increases generally with decreasing pH of the test media. However, even at a comparable pH, the release rate may be different due to differences in the interaction between the particle surface and specific media.

    The nature of particles is essentially different compared to massive sheet in terms of physical shape, surface composition and morphology. The surface area, and even the surface composition of metallic particles, depend on the particle size. The specific surface area of particles, area per mass, is intimately related to the particle size and has a large effect on the metal release process. Release rates increase with decreasing particle size due to a larger active surface area that takes part in the corrosion/dissolution process. The surface area that actually is active in the corrosion and metal release process (the effective area) governs the metal release process for both particles and massive sheet of metals or alloys. For particles, the effective surface area depends also on agglomeration conditions of particles during exposure.

  • 303.
    Millinger, Jonas
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Elkraftteknik.
    Wallmark, Oskar
    KTH, Skolan för elektro- och systemteknik (EES), Elkraftteknik.
    Soulard, J.
    Influence of lamination thickness on harmonic losses in 2-pole slotless permanent-magnet motors2017Ingår i: 2017 IEEE International Electric Machines and Drives Conference, IEMDC 2017, Institute of Electrical and Electronics Engineers (IEEE), 2017, artikel-id 8002064Konferensbidrag (Refereegranskat)
    Abstract [en]

    This paper presents an original theoretical and experimental investigation of the iron losses for three different commercially available non-oriented silicon-iron (SiFe) steel grades (with lamination thicknesses 0.1, 0.2 and 0.3 mm) in a 2-pole slotless permanent magnet motor. The study is conducted over a wide frequency range (10-100 kHz), which is a novelty. The corresponding winding losses are succesfully identified for this purpose. The impact of temperature is also studied. The results show that that iron losses compose a significant share of the total losses beyond 50 kHz. Stator harmonic iron losses at 100 kHz can be decreased with 30% by using NO10 instead of NO30.

  • 304.
    Mittal, Nitesh
    Univ Hong Kong, Dept Mech Engn, Hong Kong, Hong Kong, Peoples R China.
    Perturbation-indUniv Hong Kong, Dept Mech Engn, Hong Kong, Hong Kong, Peoples R Chinauced droplets for manipulating droplet structure and configuration in microfluidics2015Ingår i: Journal of Micromechanics and Microengineering, ISSN 0960-1317, E-ISSN 1361-6439, Vol. 25, artikel-id 084009Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this work, we mechanically perturb a liquid-in-liquid jet to manipulate the size and structure of the droplets formed from break-up of the jet. The induced break-up is relatively insensitive to fluctuations in the surrounding fluid flow. When the amplitude of perturbations is large and the interfacial tension of the liquid-liquid system is low, the size of the droplets can be precisely tuned by controlling the rate at which the liquid exits the tip of the dispensing nozzle through the frequency of perturbation. When applied to microfluidic devices with the appropriate geometry, our perturbation-induced droplet approach offers a strategy to manipulating droplet structures. We demonstrate that by varying the imposed perturbation frequency and phase lag, the structure of the multi-compartmental drops and the configuration of the resultant drops in the same flow condition can be manipulated. Moreover, after careful treatment of the wettability of the devices, we show that the structure of the droplets can be precisely controlled to change from single emulsion to double emulsion within the same device. The perturbation-induced droplet generation represents a new paradigm in the engineering of droplets, enhancing current droplet-based technologies for applications ranging from particle fabrication to confined micro-reactions.

  • 305.
    Monokrousos, Antonios
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Mekanik, Stabilitet, Transition, Kontroll. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Brandt, Luca
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Control of a separating boundary layer with travelling waves on the wall2011Rapport (Övrigt vetenskapligt)
    Abstract [en]

    We perform numerical simulations of control of a separating laminar boundary layer by means of blowing and suction at the wall in the form of traveling waves. Separation is imposed by prescribing accelerating and decelerating free-stream velocity for the flow over a flat plate. We find that downstream traveling waves already at very low amplitudes are able to eliminate the separation and induce a turbulent but attached boundary layer flow. Upstream traveling waves of relatively higher amplitudes only slightly reduce separation while keeping the flow laminar. The amplitude of the blowing/suction needed to achieve such significant effects are considerably smaller than those previously considered for drag reduction and transition delay in plane geometries.

  • 306.
    Monokrousos, Antonios
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Mekanik, Stabilitet, Transition, Kontroll. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Brandt, Luca
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Mavriplis, Catherine
    Henningson, Dan Stefan
    KTH, Skolan för teknikvetenskap (SCI), Mekanik, Stabilitet, Transition, Kontroll.
    Optimal disturbances above and upstream a flat plate with an elliptic leading edge2011Rapport (Övrigt vetenskapligt)
    Abstract [en]

    Adjoint-based iterative methods are employed in order to compute linear optimal disturbances in a spatially growing boundary layer around an elliptic leading edge. The Lagrangian approach is used where an objective function is chosen and constraints are assigned. The optimisation problem is solved using power iterations combined with a matrix-free formulation, where the state is marched forward in time with a standard DNS solver and backward with the adjoint solver until a chosen convergence criterion is fulfilled. We consider the global and the upstream localised optimal initial condition leading to the largest possible energy amplification at time T. We found that the twodimensional initial condition with the largest potential for growth is a Tolmien-Schlichting-like wave packet that includes the Orr mechanism and is located inside the boundary layer, downstream of the leading edge. Three-dimensional disturbances induce streaks by the lift-up mechanism. Localised optimal initial condition enables us to better study the effects of the leading edge; with this approach we propose a new method to study receptivity. Two-dimensional upstream disturbances, are inefficient at triggering an unstable eigenmode. The three-dimensional disturbances instead induce elongated streamwise streaks; both the global and upstream localised disturbances give significant growth. This advocates for high receptivity to three-dimensional disturbances.

  • 307.
    Muhr, Sandra
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Flerskalig materialmodellering.
    Aytekin, Kasim
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Flerskalig materialmodellering.
    Woven steel mesh for usage in beds: A case study for IKEA2016Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    This study examines whether woven metal mesh is an appropriate option for usage in beds and what material the mesh should consist of to best be suited for the purpose. The woven steel mesh’s construction was based on a reference model that consists of cross-linked rods and wires.

    Since the aim of the project was to reach a conclusion of the mesh’s usability in beds, different parameters were examined and taken into consideration. These parameters were the durability of the mesh when carrying human weight, acoustic properties to minimize chatter when lying on the mesh and rolling properties.

    The durability was examined using COMSOL multiphysics. Acoustics were studied through a literature review and rolling properties were calculated using measurements on the reference model. A material investigation was done in the database software CES EduPack.

    It was found that steel, stainless steel and aluminum fulfilled the requirements set on durability. Stainless steel was considered too expensive and steel too heavy. Using aluminum halves the weight of the mesh in comparison to steel but doubles the price, in this case however the weight was considered to be a parameter of greater importance overriding price.

  • 308.
    Munoz, Romain
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Keramteknologi.
    Co-precipitation of Y2O3 powder2011Självständigt arbete på avancerad nivå (magisterexamen), 30 poäng / 45 hpStudentuppsats (Examensarbete)
  • 309.
    Muwanguzi, Abraham Judah Bumalirivu
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Investigating the parameters that influence the behaviour of natural iron ores during the iron production process2013Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    In the iron production processes, sinters and pellets are mostly used as raw materials due to their consistency with respect to physical and chemical properties. However, natural iron ores, as mined, are rarely used directly as a feed material for iron processing. This is mainly due to the fact that they have small contents of iron and high concentration of impurities. Moreover, they swell and disintegrate during the descent in the furnace as well as due to low melting and softening temperatures. This work involves an investigation of the parameters that influence the use of natural iron ores as a direct feed material for iron production. Furthermore, it points out ways in which these can be mitigated so as to increase their direct use in iron production.

    Natural iron ore from Muko deposits in south-western Uganda was used in this study. Initially, characterisation of the physical and chemical properties was performed, to understand the natural composition of the ore. In addition, investigations were done to study the low temperature strength of the ore and its behaviour in the direct reduction zone. Also, simulations were performed with three models using the experimental data from the direct reduction experiments in order to determine the best model for predicting the direct reduction kinetics of natural iron ores.

    Chemical analyses showed that the Muko ore represents a high grade of hematite with an Fe content of 68% on average. The gangue content (SiO2+Al2O3) in 5 of the 6 investigated iron ore samples was < 4%, which is within the tolerable limits for the dominant iron production processes. The S and P contents were 0001-0.006% and 0.02-0.05% respectively. These can be reduced in the furnace without presenting major processing difficulties. With respect to the mechanical properties, the Muko ore was found to have a Tumble Index value of 88-93 wt%, an Abrasion Index value of 0.5-3.8 wt% and a Shatter Index value of 0.6-2.0 wt%. Therefore, the ore holds its form during the handling and charging processes.

    Under low temperature investigations, new parameters were discovered that influence the low temperature strength of iron oxides. It was discovered that the positioning of the samples in the reduction furnace together with the original weight (W0) of the samples, have a big influence on the low temperature strength of iron oxide. Higher mechanical degradation (MD) values were obtained in the top furnace reaction zone samples (3-25% at 500oC and 10-21% at 600oC). These were the samples that had the first contact with the reducing gas, as it was flowing through the furnace from top to bottom. Then, the MD values decreased till 5-16% at a 500oC temperature and 6-20% at a 600oC temperature in the middle and bottom reaction zones samples. It was found that the obtained difference between the MD values in the top and other zones can be more than 2 times, particularly at 500oC temperature. Furthermore, the MD values for samples with W0 < 5 g varied from 7-21% well as they decreased to 5-10% on average for samples with W0 ≥ 5 g. Moreover, the MD values for samples taken from the top reaction zone were larger than those from the middle and bottom zones.

    During direct reduction of the ores in a H2 and CO gas mixture with a ratio of 1.5 and a constant temperature, the reduction degree (RD) increased with a decreased flow rate until an optimum value was established. The RD also increased when the flow rate was kept constant and the temperature increased. An optimum range of 3-4g was found for natural iron ores, within which the highest RD values that are realised for all reduction conditions. In addition, the mechanical stability is greatly enhanced at RD values > 0.7. In the case of microstructure, it was observed that the original microstructure of the samples had no significant impact on the final RD value (only 2-4%). However, it significantly influenced the reduction rate and time of the DR process.

    The thermo-gravimetric data obtained from the reduction experiments was used to calculate the solid conversion rate. Three models: the Grain Model (GM), the Volumetric Model (VM) and the Random Pore Model (RPM), were used to estimate the reduction kinetics of natural iron ores. The random pore model (RPM) provided the best agreement with the obtained experimental results (r2 = 0.993-0.998). Furthermore, it gave a better prediction of the natural iron oxide conversion and thereby the reduction kinetics. The RPM model was used for the estimation of the effect of original microstructure and porosity of iron ore lumps on the parameters of the reduction process.

  • 310.
    Muwanguzi, Abraham Judah Bumalirivu
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Alevanau, Aliaksandr
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Application of different models for the prediction of the kinetics of direct reduction of natural iron oresManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Simulation of the direct reduction conditions was performed in a laboratory furnace. Lump samples from natural hematite iron ore were reduced by a gas mixture of H2 and CO (H2/CO =1.5) at temperatures 700, 800 and 900°C. The effect of reduction temperature on the reduction degree, reduction rate of samples and carbon deposition were investigated and discussed in this study. The thermo-gravimetric data obtained from the reduction experiments was run in a programme that calculates the solid conversion rate. Also, three models: i) Grain Model (GM), ii) Volumetric Model (VM) and iii) the Random Pore Model (RPM), were used to estimate the reduction kinetics of natural iron ores. It was found that the RPM model result agreed best with the obtained experimental results. Furthermore, it gave better predictions of the natural iron oxide conversion and thereby the reduction kinetics.

  • 311.
    Muwanguzi, Abraham Judah Bumalirivu
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Andrey, Karasev V
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Joseph, Byaruhanga K
    Makerere University, Kampala.
    Pär, Jönsson G
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Characterisation of the Physical and Metallurgical Propertiesof Natural Iron Ore for Iron Production2012Ingår i: ISRN Materials Science, ISSN 2090-6080, E-ISSN 2090-6099, Vol. 2012, s. 9-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The blast furnace is still the dominant form of iron production, but over the years, direct reduction methods have increased due to a number of reasons. Overall, iron production methods have optimal requirements with respect to the feed materials especially iron ore. In this study, tests were carried out on Muko iron ore from Uganda to analyse its suitability to meet the feed requirements of today's dominant iron production methods. More specifically, the Tumbler, Abrasion, and Shatter Indices of the ore were determined. In addition, porosity, thermoanalysis, and reducibility tests were performed. Overall, the Muko ore was found to have good mechanical properties exemplified with tumble and shatter index data >89.0 wt% and <2.5 wt%, respectively. Furthermore, its reducibility at 0.87%/min is within the acceptable range as a natural material feed for blast furnace and direct reduction furnaces. Also, the energy requirement for heating the ore to 1100°C was found to be higher in the samples containing a wider size range of irregular grains and the largest contaminations. In summary, it is concluded that the Muko iron ore has good physical and metallurgical properties to serve as a natural material for the blast furnace and direct reduction furnaces.

  • 312.
    Muwanguzi, Abraham Judah Bumalirivu
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Karasev, Andrey
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Joseph, Byaruhanga K
    Makerere University, Kampala.
    Pär, Jönsson G
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Characterization of chemical composition and microstructure of natural iron ore from Muko deposits2012Ingår i: ISRN Materials Science, ISSN 2090-6080, E-ISSN 2090-6099, Vol. 2012, s. 9-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The study aimed at investigating the chemical composition and microstructure of raw iron ore from the deposits in Muko area (south-western Uganda). The quality of this iron ore was evaluated to establish its suitability to serve as a raw material for iron production. Samples were taken from the six hills of Muko ore deposits and tests carried out to establish their composition and properties. X-ray diffraction and scanning electron microscopy were employed in the investigation and chemical analysis performed to determine the compounds constituting the ore. The quality of this ore was compared to generalized world market standards and ores from other nations. It was found that Muko ore is a rich hematite grade with Fe content above 65%. It has little gangue (<6% SiO2 and 3-4% Al2O3) and low contents of the deleterious elements (P ~ 0.02% and S < 0.006%), which correspond to acceptable levels for commercial iron ores.

  • 313.
    Muwanguzi, Abraham Judah Bumalirivu
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Karasev, Andrey Vladimirovich
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Byaruhanga, Joseph Kadoma
    Makerere University, Kampala.
    Jönsson, Pär G.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Effect of different factors on low temperature degradation of hematite iron ore during reduction2014Ingår i: Metallurgical Research and Technology, ISSN 2271-3646, Vol. 111, nr 1, s. 57-66Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Low temperature degradation (LTD) of iron oxides was investigated with the aim of understanding how natural iron ores degrade under different conditions. Minimisation of this degradation would increase the acceptance level of natural iron ores as feed materials without prior beneficiation. In addition to temperature and reduction gas composition, sample positioning in the reduction furnace and sample's original weight were also found to influence LTD. Samples placed in the top reaction zone of the furnace, which have the first contact with the reducing gas, were found to degrade 1.5 times more than those in the middle and bottom reaction zones. In addition, they presented a wide range of size in the disintegrated particles than those in the middle and bottom reaction zones. Furthermore, the samples with an original weight equal to or greater than 5 g, had a disintegration extent of less than 10%. Therefore, if the reduction gas comes into contact with a certain material first, before contacting the iron oxide, it may serve to reduce on LTD during reduction. Furthermore, in laboratory conditions, the occurrence of low temperature breakdown of the natural iron oxides can be minimised by using samples with an original weight equal to or greater than 5 g.

  • 314.
    Muwanguzi, Abraham Judah Bumalirivu
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Yunyun, Wu
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Andrey, Karasev V
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Joseph, Byaruhanga K
    Makerere University, Kampala.
    Pär, Jönsson G
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad processmetallurgi.
    Investigation of direct reduction of lumps from natural hematite iron ore2013Ingår i: Research and Application of Material, ISSN 2328-5079Artikel i tidskrift (Övrigt vetenskapligt)
    Abstract [en]

    The effects of the main characteristics of hematite natural ore lumps such as weight and microstructure and the parameters of the direct reduction process (gas flow rate and temperature) on the reduction degree and thermo-mechanical degradation of iron ore lumps were investigated. Lumps from Muko deposit were used for direct reduction with H2/CO, ratio of 1.5. The temperature and gas flow rate ranged from 700-900°C and 0.25-1.0 L/min, respectively. The highest reduction degree (0.88-0.91) was obtained by direct reduction of 3-4 g samples at 900°C and 0.5 L/min. The effects of the flow rate of the reduction gas in the furnace and the carbon deposited on a sample surface on the accuracy of the weight measurement and the reduction degree by using the thermal gravimetric technique were estimated and discussed. It was further discovered that the natural microstructure of a lump iron ore has an effect on the reduction time.

  • 315.
    Myrsell, Johan
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Effect of shot blasting on processoxidised stainless steel – morphology,chemistry and pickling performance2014Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The oxide scale created during manufacturing of stainless steel is often removed by a chemical pickling with mixed acid. Various pre-treatments to pickling are also applied to increase the efficiency of the oxide scale removal. Shot blasting is one such pre-treatment, which operates to remove a certain amount of oxide and also to generate cracks and openings for the subsequent pickling. In this work, three materials, AISI 2205, 430 and 304 have been blasted and later exposed to mixed acid. This was conducted to quantify the effect shot blasting has on the subsequent pickling of stainless steel. Three shot products and two blasting parameters were investigated and varied. Shot blasting significantly reduced the oxide scale but was unable to remove the chromium oxide layer closest to the steel surface. No significant difference was observed when comparing the result from the three shot products after blasting. Increasing the particle velocity or the coverage rate further enhanced the pickling but reduced the amount of oxide removed during blasting. These effects are however relative small, so in practise relatively mild conditions seems preferable for economic reasons. Oxide scale containing hematite was difficult to remove by both shot blasting and pickling. 

  • 316.
    Möller, Björn
    KTH, Tidigare Institutioner, Maskinkonstruktion.
    Modular mechatronic mechanism2004Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
  • 317.
    Nagar, Sandeep
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Teknisk materialfysik.
    Multifunctional magnetic materials prepared by Pulsed Laser Deposition2012Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

         Pulsed LASER deposition (PLD) is widely recognized as excellent deposition technique owing to stoichiometric transfer of target material, easy preparation and high quality. Thin films from few nanometers to micrometer regime can be fabricated with equal ease. Although a batch process is not suitable for mass scale industrial production, PLD is a versatile technique, efficient and convenient for high quality basic research.  This thesis illustrates the use of PLD technique to study the emerging trends in tailoring multifunctional magnetic thin films both from basic nanoscience and device development point of view.

         After a comprehensive review of magnetism in chapter 1: entitled ‘A journey through classical to modern trends in magnetism, and multifunctional thin film devices’ followed by a reasonably thorough discussion on Pulsed Laser thin film technique in Chapter 2, we present:

    1. Studies of tailoring composite high energy product permanent magnetic FePtB based thin films for applications in NEMS /MEMS, (Chapter 3).
    2. Study of search for new multiferroic materials by investigating the properties of Chromites. Crystalline Chromites are antiferromagnetic below 150oC.  However depositing thin films by PLD of the crystalline 95.5% dense targets produced by Surface Plasma Sintering, we discovered that the resulting films were amorphous and ferromagnetic beyond room temperature. Moreover advanced spectroscopic techniques revealed that the amorphized state is metallic with Cr in a mixed valence state.   An understanding of the underlying physics of the observed phenomenon has been carried out based on first principles calculations.  These results are now being considered for publication in a high profile journal.  Extensive studies on the films showing that these materials are ferromagnetic, but not ferroelectric are discussed in chapter 4. A preliminary presentation of these studies was pier reviewed and published in MRS symposium proceedings.
    3. Fabrication of Room temperature, Transparent, high moment soft ferromagnetic amorphous Bulk metallic glass based FeBNbY thin films by PLD, suitable for Nanolithography in NEMS/MEMS device development .  (Chapter 5)

    From a basic study point of view on new trends on magnetism we present:

    4. The use of PLD technique to demonstrate room temperature ferromagnetism in undoped MgO, and V-doped MgO thin films.  Both of these oxides which do not contain any intrinsically magnetic elements and are diamagnetic in their bulk form belong to a new class of magnetic films, the so called d0magnets signifying that robust above room temperature ferromagnetism arising from defects and controlled carriers and no occupied d-states can be tailored in semiconductors and insulators.  These, mostly ZnO and MgO based thin films which may be classified as Dilute Magnetic Semiconductors, DMS, and Dilute Magnetic Insulators, DMI, are now the materials of active interest in future Electronics involving components which exploit both charge and spin of electrons in the arena of SPINTRONICS.

    Extensive characterization of magnetic, electrical, optical properties and microscopic structure has ensured development of high quality magnetic materials for future applications. Further research on these promising materials is expected to yield new generation spintronic devices for better performance in terms of efficiency, energy consumption and miniaturization of sizes.

  • 318.
    Nakamura, Keisuke
    et al.
    Tohoku Univ, Dept Adv Free Rad Sci, Grad Sch Dent, Aoba Ku, 4-1 Seiryo Machi, Sendai, Miyagi 9808575, Japan..
    Ankyu, Shuhei
    Sweden Dent Sendai, Miyagino Ku, 1-6-2 Tsutsujigaoka, Sendai, Miyagi 9830852, Japan..
    Nilsson, Fritjof
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Fiber- och polymerteknologi, Polymera material.
    Kanno, Taro
    Tohoku Univ, Dept Adv Free Rad Sci, Grad Sch Dent, Aoba Ku, 4-1 Seiryo Machi, Sendai, Miyagi 9808575, Japan..
    Niwano, Yoshimi
    Shumei Univ, Fac Nursing, 1-1 Daigaku Cho, Yachiyo, Chiba 2760003, Japan..
    von Steyern, Per Vult
    Malmo Univ, Fac Odontol, Dept Mat Sci & Technol, SE-20506 Malmo, Sweden..
    Örtengren, Ulf
    Univ Gothenburg, Sahlgrenska Acad, Inst Odontol, Dept Cariol, SE-40530 Gothenburg, Sweden.;Arctic Univ Norway, Fac Hlth Sci, Dept Clin Dent, N-9037 Tromso, Norway..
    Critical considerations on load-to-failure test for monolithic zirconia molar crowns2018Ingår i: Journal of The Mechanical Behavior of Biomedical Materials, ISSN 1751-6161, E-ISSN 1878-0180, Vol. 87, s. 180-189Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Application of monolithic zirconia crowns (MZCs) with reduced thickness to the molar region has been proposed, but potential complications have yet to be fully evaluated in laboratory tests. The present study aimed to develop a clinically relevant load-to-failure test in combination with fatigue treatments involving thermal and mechanical cycling (TC and MC) to evaluate the fracture resistance of molar MZCs. MZCs with a minimal thickness of 0.5 mm were bonded to dies made of resin-based composite (RBC), epoxy resin (EP), or polyoxymethylene-copolymer (POM-C). The samples were either untreated (UT) or subjected to TC (5-55 degrees C for 1 x 10(5) cycles) and MC (300 N for 2.4 x 10(6) cycles). The stress generated by TC and MC was simulated by finite element modeling. The load-to-failure test was performed using an inverse V-shaped two-plane indenter and was followed by fractographic analysis. The median values of fracture load for MZC/RBC and MZC/EP in the TC group were significantly lower than those in the UT group. MC also decreased the median value of fracture load for MZC/RBC significantly, but not that for MZC/EP and MZC/POM-C. Fractography revealed that the fracture started in the cervical area in all groups, which is similar to clinically failed crowns. The simulation confirmed stress concentration at the cervical area in both TC and MC groups. The present study suggests that the load-to-failure test using a two-plane indenter could induce clinically relevant fracture of MZCs, the vulnerability of the MZCs depends largely on the die material employed, and MZCs are more likely to be damaged by thermal fatigue than mechanical fatigue.

  • 319.
    Naraghi, Reza
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Metallografi.
    Selleby, Malin
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Metallografi.
    Ågren, John
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Metallografi.
    Thermodynamics of stable and metastable structures in Fe-C system2014Ingår i: Calphad, ISSN 0364-5916, E-ISSN 1873-2984, Vol. 46, s. 148-158Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The thermodynamic properties and the phase diagram of the Fe-C system are reviewed by means of the CALPHAD method and Gibbs energy functions valid from 0 K upwards are presented. The Fe-C system has been evaluated previously by Gustafson. The information on thermodynamic properties and phase equilibria have now been updated and used as a basis to re-optimize the model parameters. In addition, thermodynamic properties of metastable cementite, Hagg and eta carbides are evaluated on the basis of available experimental data and taking into account the magnetic nature of these carbides. Moreover, a model is proposed for carbon ordering phenomena in martensite. Structural changes during early stages of aging of martensite are described using the proposed model and tempering equilibria with cementite, Hagg, and eta carbides are well reproduced. It should also been mentioned that the present description represents experimental data on the equilibrium with the liquid better than Gustafson's thermodynamic description.

  • 320.
    Neumeister, Jonas M.
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Hållfasthetslära (Inst.).
    Melin, L. Niklas
    KTH, Skolan för teknikvetenskap (SCI), Hållfasthetslära (Inst.).
    Specimen clamping and performance of the Ioisipescu shear tests applied for composite materials2007Ingår i: 16th International Conference on Composite Materials, ICCM-16, 2007Konferensbidrag (Refereegranskat)
    Abstract [en]

    Clamping and subsequent loading in shear of Ioispescu specimens is investigated. Combined stresses reach similar, or even higher, levels locally compared the nominal shear stress, both compressive and tensile. Especially for brittle materials, composites, and materials with anisotropic failure modes, these stresses may cause premature failure outside the test region and appropriate clamping levels become important. A clamping ratio (r) between clamping force and peak shear force is introduced, and it is shown that for quasi-isotropic failure modes, the overall lowest detrimental stresses are obtained for about r ∼ 1. It is further shown that loss of contact always occurs in one part of the clamping region unless r is in excess of 2.5-3. Near that loss of contact, high tensile stresses are obtained. Even with moderate r, there will be local plasticity or crushing etc due to high contact pressure near the end of the opposing gripping face. These findings are shown both numerically and experimentally using optical full field strain measurements.

  • 321.
    Nilsson, Robin
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Experimental Methodologies for Analyzing Austenite Recrystallization in Martensitic Tool Steels2015Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Revealing the prior austenite grain boundaries from a martensitic structure is well known to be very difficult and dependent on the chemical composition and the thermomechanical processing of the steel. In the present study, four different chemical etching reagents and additional thermal etching have been conducted for thermomechanical simulated tool steels Orvar Supreme and Stavax ESR. The etching results have been characterized using light optical microscopy and electron backscattered diffraction.

    The obtained results show that saturated aqueous picric acid, oxalic and sodium bisulfite based acid reveals prior austenite grain boundaries well for Orvar Supreme. For Stavax ESR, only aqueous CrO3-NaOH-picric acid provides good results in revealing the prior austenite grain boundaries. Thermal etching shows good potential and if conducted properly, thermal etching is a good alternative to the chemical reagents from a health- and environmental perspective.

  • 322.
    Norberg, Sven
    KTH, Skolan för teknikvetenskap (SCI), Hållfasthetslära (Inst.), Hållfasthetslära (Avd.).
    Prediction of the fatigue limit: accuracy of post-processing methods2006Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Several fatigue criteria were evaluated with experimental fatigue test data. The fatigue tests contained many different geometries with different degrees of stress concentration. It was concluded that the differences between the criteria were neglectable when compared to the differences between the specimens. The stress concentrations with the stress gradients and sizes of the highly stresses volumes that resulted were very important. In order to understand this, gradient and volume methods were investigated. The gradient methods showed some improvement over the strictly local evaluation first attempted. The volume method, a weakest link application with a Weibull distribution of the fatigue strength, yielded results useable for actual design situations. The volume method is strongly recommended and the choice of criterion does not seem to be very important.

  • 323.
    Norberg, Sven
    KTH, Skolan för teknikvetenskap (SCI), Hållfasthetslära (Inst.).
    Stress based high cycle fatique criteria: a literature survey2006Rapport (Övrigt vetenskapligt)
  • 324.
    Norberg, Sven
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Hållfasthetslära (Inst.).
    Olsson, Mårten
    KTH, Skolan för teknikvetenskap (SCI), Hållfasthetslära (Inst.).
    A fast, versatile fatigue post-processor and criteria evaluation2005Ingår i: International Journal of Fatigue, ISSN 0142-1123, E-ISSN 1879-3452, Vol. 27, nr 10-12, s. 1335-1341Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper is concerned with the development and use of a general High Cycle Fatigue (HCF) post-processor, FAST, Fatigue AnalysiS Tool. It is used to evaluate and develop HCF criteria. FAST can handle many kinds of criteria and evaluate them with fatigue test results from both standard test specimens and actual components. When a reliable criterion exists, FAST will be used for design purposes. The principles of FAST are outlined and an example is given where seven local multiaxial stress based criteria are evaluated, along with the commercial fatigue post-processor Femfat. The conclusion is that a correct treatment of the volume or stress gradient effect is more important than the choice of criterion.

  • 325.
    Norberg, Sven
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Hållfasthetslära (Inst.).
    Olsson, Mårten
    KTH, Skolan för teknikvetenskap (SCI), Hållfasthetslära (Inst.).
    The effect of loaded volume and stress gradient on the fatigue limit2007Ingår i: International Journal of Fatigue, ISSN 0142-1123, E-ISSN 1879-3452, Vol. 29, nr 12, s. 2259-2272Artikel i tidskrift (Refereegranskat)
    Abstract [en]

     In this paper an investigation of multiaxial stress based criteria and evaluation methods is presented. The criteria are used with the point, gradient and volume methods. The purpose is to determine the combination of criteria and methods that is best suited for design against the fatigue limit. The evaluation is based on elastic FE-analysis of 15 geometries for which the fatigue limit loads are known. The point method is based on the maximum values of the fatigue stress in each specimen. With the gradient method, the fatigue stress is adjusted with the relative or absolute gradient of the fatigue stress itself. With the volume method, a statistical size effect is considered, by use of a weakest link integral. Thus, the probability of fatigue depends on the fatigue stress distribution. Also, the gradient and volume methods are combined. The results show that the point and gradient methods are not good for prediction of the fatigue limit. It is recommended to use the volume method in fatigue design. It is accurate enough for prediction of the fatigue limit, straightforward to use and easy to interpret. The choice of method is much more important than the choice of criteria.

  • 326.
    Nordin, Erland
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Hållfasthetslära (Inst.). Scania CV AB, Sweden.
    Alfredsson, Bo
    KTH, Skolan för teknikvetenskap (SCI), Hållfasthetslära (Inst.).
    Experimental Investigation of Shot Peening on Case Hardened SS2506 Gear Steel2017Ingår i: Experimental techniques (Westport, Conn.), ISSN 0732-8818, E-ISSN 1747-1567, Vol. 41, nr 4, s. 433-451Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Shot peening is a manufacturing process commonly used to increase fatigue life in components for the automotive and aircraft industry. In this paper the effect of shot peening is described for a case hardened gear steel. For gears there are three main factors from shot peening that influence fatigue life: residual stresses, microstructure and surface roughness. The paper describes an experimental series where these parameters were measured for common industrial shot peening settings. The aim was to show how several different measurement techniques and results correspond to each other for certain shot peening parameters. The aim was also to gather experimental results that can be used for verification of shot peening simulations. To simplify measurements and decrease variation, flat steel plates were used as targets. Residual stress, full width at half maximum (FWHM), retained austenite, surface roughness/topology, hardness and Barkhausen noise were measured and related to microstructural changes. The mean indentation diameter was measured for individual shots at low coverage of each intensity which was used to determine the average velocity of the media. The mean diameter and hardness of the shot peening media was also determined.

  • 327.
    Nordström, Joakim
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Straightening and its influence on the final mechanical properties in cold worked stainless steel2012Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The main purpose with this investigation was to clarify when or if specific grades will soften or harden during the straightening process in a seven roll cross roll straightening machine. The aim was solely made to include tubes which had been cold worked to achieve high yield strength levels.

    The straightening process will induce lengthwise tensile and compressive stress and strain. According to theory straightening could therefore also induce considerable Bauschinger effect. 

    Physical tests, with material from pilgered tubes, in a laboratory environment were performed to give a well-defined set up of the strain levels and sign of the same. Real in process trials were also performed. Parallel to the physical laboratory tests and the real process tests a FEM-simulation and a FEM-model to calculate strain levels was developed. 

    Two material types were investigated, but the results are only unambiguous for material A. Further investigations need to be done on material B to give a clear picture.

  • 328.
    Nurhussen, Filli
    KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Experimental studies on mouse slow and fast twitch muscles2006Licentiatavhandling, monografi (Övrigt vetenskapligt)
    Abstract [en]

    This thesis deals with physiological and mechanical properties of fast and slow twitch mouse muscles. It discusses isometric, concentric and eccentric contractions of mouse extensor digitorum longus ('EDL') and soleus ('SOL') muscles. This project primarily investigated the behaviors of muscles, to give better understanding and improved descriptions for the human system, when subjected to impact or sustained high loading conditions.

    Muscle force has been shown to be length and activation dependent. The effect of passive or active length changes on muscle force production was studied. Isometric activation showed a maximal force at optimum length for each individual muscle, to which all experiments were related. This optimum length was stimulation frequency dependent and maximum produced force shifted towards shorter length with increasing frequency.

    Active shortening of maximally stimulated muscle was shown to produce reduced force, but also a reduced isometric force (force depression) following shortening, regardless of the shortening conditions and the method of muscle stimulation.

    Steady state force depression (ΔFstdep) was correlated with the instant force depression ΔFidep, pre-activation time, t0-t1 and the work (WS), performed by the muscle during shortening. It was positively correlated with the ΔFidep when the shortening magnitude was varied ('VSM'). But in varying the shortening velocity ('VST'), it was negatively correlated with the instant force depression.

    In active stretch, force was analogously enhanced during stretch, and this effect remained after stretch. Steady state force enhancement (ΔFstenh)following muscle stretch was correlated with the instant force enhancement,ΔFienh, pre-activation time, t0-t1 and the work (WL), done on the muscle during stretch. It was positively correlated with ΔFienh when the stretch magnitude was varied ('VLM'). But in varying the stretch velocity ('VLT'), ΔFstenh was negatively correlated with ΔFienh.

    Furthermore, the rise time constant, (Tr) of redeveloped isometric forces following the

    shortening and the fall time constant, (Tf) of the relaxed isometric force following muscle stretch were calculated. In VSM, Tr and Fstdep were positively correlated with each other, while in VST, they were negatively correlated. Tf and Fstenh were negatively correlated in both VLM and VLT.

  • 329.
    Ohlson, Nils-Gunnar
    KTH, Skolan för teknikvetenskap (SCI), Hållfasthetslära (Inst.).
    Use of viscoplastic models for prediction of deformation of polymer parts2010Ingår i: Society for Experimental Mechanics - SEM Annual Conference and Exposition on Experimental and Applied Mechanics 2010: Volume 3, 2010, s. 827-836Konferensbidrag (Refereegranskat)
    Abstract [en]

    Polymers are extensively used in engineering applications, ranging from sealing rings to dampers and springs in centrifugal separators as well as in micro robots with piezoelectric excitation. The mechanical behaviour of these materials is highly non-linear and may be described by integral equations, taking into account the load history of the part considered. Paper shows taht long-term deformation in creep and relaxation can be derived from tensile tests at several loading rates. The influence of cyclic loading is discussed. Tests show that material can fail in fatigue.

  • 330.
    Okeke, Joseph
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Pyrolysis of Agricultural Straw Using High Temperature Steam2010Självständigt arbete på avancerad nivå (masterexamen), 80 poäng / 120 hpStudentuppsats (Examensarbete)
  • 331.
    Olasz, Lorant
    KTH, Skolan för teknikvetenskap (SCI), Hållfasthetslära (Inst.), Hållfasthetslära (Avd.).
    Residual Stresses and Strains in Cross-linked Polyethylene Power Cable Insulation2006Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The subject of this thesis is modeling of the manufacturing process of high voltage power cables with the aim of predicting residual stresses and strains in the cable insulation. The studied material is cross-linked polyethylene (XLPE), which at room temperature is a semi-crystalline viscoelastic solid. Above the crystallization temperature the material exhibits a rubber type behavior due to the crosslinks.

    An extensive set of uniaxial tensile relaxation tests were used for the mechanical characterization of XLPE. These experiments were complemented by pressure volume temperature experiments as well as density and crystallinity measurements. Based on the experiments, initially a linear and later a non-linear viscoelastic power law model was formulated, incorporating temperature and crystallinity dependence. The non-linear model is based on the Schapery formulation. Evaluations of the model were performed with additional uniaxial experiments. These included comparisons between predicted stress responses and measured values during relaxation tests with transient temperature histories, during two step relaxation experiments and during uniaxial tests with constant strain rate loading.

    The initial modeling work focused on the prediction of residual stresses which develop during the cooling stage of the manufacturing process. As the constitutive model incorporates temperature and crystallinity dependence, the mechanical problem is coupled to the heat transfer and crystallization problems. Calculations were performed for a vertical manufacturing line. The effects of a viscoelastic material model are illustrated by a comparison to a stress state predicted by a thermo-elastic material model.

    A final study concerns the modeling of the residual strains in the insulation. It was found that strains originating at cross-linking of the molecules play a signifi- cant role for buildup of residual strains. Calculations are performed for the same vertical process line as before. Good agreement was found between predicted and experimentally obtained residual strains. Based on the residual strain state an estimate is made for the upper limit of shrink-back of the cable insulation.

  • 332.
    Olasz, Lorant
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Hållfasthetslära (Inst.).
    Gudmundson, Peter
    KTH, Skolan för teknikvetenskap (SCI), Hållfasthetslära (Inst.).
    Prediction of residual stresses in cross-linked polyethylene cable insulation2005Ingår i: Polymer Engineering and Science, ISSN 0032-3888, E-ISSN 1548-2634, Vol. 45, nr 8, s. 1132-1139Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Modeling of the manufacturing process of high-voltage power cables was performed with the aim of predicting residual stresses in the cable insulation. A viscoelastic power law-type constitutive model was used which incorporates temperature and crystallinity dependence of the parameters. In this way the mechanical problem is coupled to the heat transfer and crystallization problems. In order to illustrate the effects of relaxation, a comparison to a thermoelastic material model is made.

  • 333.
    Olasz, Lorant
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Hållfasthetslära (Inst.).
    Gudmundson, Peter
    KTH, Skolan för teknikvetenskap (SCI), Hållfasthetslära (Inst.).
    Residual strains in XLPE high voltage cable insulation2006Rapport (Övrigt vetenskapligt)
  • 334.
    Olasz, Lorant
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Hållfasthetslära (Inst.).
    Gudmundson, Peter
    KTH, Skolan för teknikvetenskap (SCI), Hållfasthetslära (Inst.).
    Viscoelastic model of cross-linked polyethylene including effects of temperature and crystallinity2005Ingår i: Mechanics of time-dependant materials, ISSN 1385-2000, E-ISSN 1573-2738, Vol. 9, nr 4, s. 225-246Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Characterization of the mechanical behavior of cross-linked polyethylene (XLPE) commonly used in high voltage cable insulation was performed by an extensive set of isothermal uniaxial tensile relaxation tests. Tensile relaxation experiments were complemented by pressure-volume-temperature experiments as well as density and crystallinity measurements. Based on the experimental results, a viscoelastic power law model with four parameters was formulated, incorporating temperature and crystallinity dependence. It was found that a master curve can be developed by both horizontal and vertical shifting of the relaxation curves. The model was evaluated by making comparisons of the predicted stress responses with the measured responses in relaxation tests with transient temperature histories.

  • 335.
    Olasz, Lorant
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Hållfasthetslära (Inst.).
    Gudmundsson, Peter
    KTH, Skolan för teknikvetenskap (SCI), Hållfasthetslära (Inst.).
    A non-linear viscoelastic constitutive model for XLPE and its application in residual stress prediction for high voltage cable insulation2006Rapport (Övrigt vetenskapligt)
  • 336.
    Onifade, Ibrahim
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Byggvetenskap, Byggnadsmaterial.
    Birgisson, B.
    Damage and fracture characterization of asphalt concrete mixtures using the equivalent micro-crack stress approach2017Ingår i: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 148, s. 521-530Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper, a new parameter termed “equivalent micro-crack stress” (σmc) is proposed for the evaluation of the cracking performance of asphalt mixtures with respect to their resistance to the initiation of micro-crack. The “equivalent micro-crack stress” (σmc) is a function of the material stiffness and the “micro-crack initiation threshold” (MCIT). The MCIT is a critical strain energy density at the instance of initiation of micro-crack. Experimental testing is carried out for the evaluation of the cracking performance of unmodified and wax modified asphalt mixtures using the Superpave IDT tests at −20 °C, −10 °C and 0 °C. The low temperature range is used in the study to minimize the effect of viscoplastic dissipation on the material cracking behaviour. The result shows that the “equivalent micro-crack stress” (σmc) gives a good indication of the material cracking performance of the unmodified and wax modified mixtures. A Finite Element Analysis is performed to assess the validity of the proposed approach under cyclic loading condition in the controlled-stress mode. The result shows that there is a good agreement between the material cracking performance in both monotonic and cyclic loading conditions using the proposed approach. The higher the “effective micro-crack stress” (σmc), the better the fracture performance of the mixture.

  • 337.
    O'Reilly, Ciarán J.
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg. KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellence Center for ECO2 Vehicle design.
    Dazel, Olivier
    Université du Maine, Laboratoire d'Acoustique de l'Université du Maine, France..
    Gabard, Gwénaël
    Université du Maine, Laboratoire d'Acoustique de l'Université du Maine, France..
    Numerically solving the biot equations for sound absorbing materials using a wave expansion method2018Ingår i: 47th International Congress and Exposition on Noise Control Engineering, INTER-NOISE, Institute of Noise Control Engineering , 2018Konferensbidrag (Refereegranskat)
    Abstract [en]

    Poroelastic materials are often used in noise control applications to dissipate acoustic waves through viscous, thermal and structural effects. The prediction of sound propagation in such materials is therefore of practical interest for many engineering applications. This propagation may be described by the Biot equations. In this paper, a numerical approach known as a wave expansion method is developed to solve the Biot equations. A wave expansion method uses fundamental solutions of the wave operator and so accurate solutions to linearised propagation equations may be obtained with only two-to-three points per wavelength. The method is also robust to meshing and could be implemented in a meshless manner. These characteristics make it well suited to examining practical sound absorption applications. The method is applied to a benchmark problem and the results are compared to the analytical solution. The results are found to behave consistently at mid-to-high frequencies, but there is an increasing error due to ill-conditioning at low frequencies. 

  • 338. Oya, Y.
    et al.
    Masuzaki, S.
    Tokitani, M.
    Azuma, K.
    Oyaidzu, M.
    Isobe, K.
    Asakura, N.
    Widdowson, A. M.
    Heinola, K.
    Jachmich, S.
    Rubel, Marek
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Fusionsplasmafysik.
    Contributors, JET
    Correlation of surface chemical states with hydrogen isotope retention in divertor tiles of JET with ITER-Like Wall2018Ingår i: Fusion engineering and design, ISSN 0920-3796, E-ISSN 1873-7196, Vol. 132, s. 24-28Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    To understand the fuel retention mechanism correlation of surface chemical states and hydrogen isotope retention behavior determined by XPS (X-ray photoelectron spectroscopy) and TDS (Thermal desorption spectroscopy), respectively, for JET ITER-Like Wall samples from operational period 2011–2012 were investigated. It was found that the deposition layer was formed on the upper part of the inner vertical divertor area. At the inner plasma strike point region, the original surface materials, W or Mo, were found, indicating to an erosion-dominated region, but deposition of impurities was also found. Higher heat load would induce the formation of metal carbide. At the outer horizontal divertor tile, mixed material layer was formed with iron as an impurity. TDS showed the H and D desorption behavior and the major D desorption temperature for the upper part of the inner vertical tile was located at 370 °C and 530 °C. At the strike point region, the D desorption temperature was clearly shifted toward higher release temperatures, indicating the stabilization of D trapping by higher heat load.

  • 339. Ozaki, N.
    et al.
    Nellis, W. J.
    Mashimo, T.
    Ramzan, M.
    Ahuja, Rajeev
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad materialfysik. Department of Physics and Astronomy, Uppsala University, Sweden.
    Kaewmaraya, T.
    Kimura, T.
    Knudson, M.
    Miyanishi, K.
    Sakawa, Y.
    Sano, T.
    Kodama, R.
    Dynamic compression of dense oxide (Gd3Ga5O12) from 0.4 to 2.6 TPa: Universal Hugoniot of fluid metals2016Ingår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 6, artikel-id 26000Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Materials at high pressures and temperatures are of great current interest for warm dense matter physics, planetary sciences, and inertial fusion energy research. Shock-compression equation-of-state data and optical reflectivities of the fluid dense oxide, Gcl(3)Ga(5)O(12) (GGG), were measured at extremely high pressures up to 2.6TPa (26 Mbar) generated by high-power laser irradiation and magnetically driven hypervelocity impacts. Above 0.75TPa, the GGG Hugoniot data approach/reach a universal linear line of fluid metals, and the optical reflectivity most likely reaches a constant value indicating that GGG undergoes a crossover from fluid semiconductor to poor metal with minimum metallic conductivity (MMC). These results suggest that most fluid compounds, e.g., strong planetary oxides, reach a common state on the universal Hugoniot of fluid metals (UHFM) with MMC at sufficiently extreme pressures and temperatures. The systematic behaviors of warm dense fluid would be useful benchmarks for developing theoretical equation-of-state and transport models in the warm dense matter regime in determining computational predictions.

  • 340. Panigrahi, Puspamitra
    et al.
    Araujo, C. Moyses
    Hussen, Tanveer
    Ahuja, Rajeev
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Tillämpad materialfysik. Condensed Matter Theory Group, Department of Physics and Astronomy, Uppsala University.
    Crafting ferromagnetism in Mn-doped MgO surfaces with p-type defects2014Ingår i: Science and Technology of Advanced Materials, ISSN 1468-6996, E-ISSN 1878-5514, Vol. 15, nr 3, s. 035008-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We have employed first-principles calculations based on density functional theory (DFT) to investigate the underlying physics of unusual magnetism in Mn-doped MgO surface. We have studied two distinct scenarios. In the first one, two Mn atoms are substitutionally added to the surface, occupying the Mg sites. Both are stabilized in the Mn3+ valence state carrying a local moment of 4.3 mu(B) having a high-spin configuration. The magnetic interaction between the local moments display a very short-ranged characteristic, decaying very quickly with distance, and having antiferromagnetic ordering lower in energy. The energetics analysis also indicates that the Mn ions prefer to stay close to each other with an oxygen atom bridging the local interaction. In the second scenario, we started exploring the effect of native defects on the magnetism by crafting both Mg and O vacancies, which are p-and n-type defects, respectively. It is found that the electrons and holes affect the magnetic interaction between Mn ions in a totally different manner. The n-type defect leads to very similar magnetism, with the AFM configuration being energetically preferred. However, in the presence of Mg vacancy, the situation is quite different. The Mn atoms are further oxidized, giving rise to mixed Mn(d) ionic states. As a consequence, the Mn atoms couple ferromagnetically, when placed in the close configuration, and the obtained electronic structure is coherent with the double-exchange type of magnetic interaction. To guarantee the robustness of our results, we have benchmarked our calculations with three distinct theory levels, namely DFT-GGA, DFT-GGA+U and DFT-hybrid functionals. On the surface, the Mg vacancy displays lower formation energy occurring at higher concentrations. Therefore, our model systems can be the basis to explain a number of controversial results regarding transition metal doped oxides.

  • 341. Paskova, T.
    et al.
    Paskov, P. P.
    Darakchieva, V.
    Kroeger, R.
    Hommel, D.
    Monemar, B.
    Lourdudoss, Sebastian
    KTH, Skolan för informations- och kommunikationsteknik (ICT), Mikroelektronik och Informationsteknik, IMIT.
    Preble, E.
    Hanser, A.
    Williams, M. N.
    Tutor, M.
    Strain-free low-defect-density bulk GaN with nonpolar orientations2006Konferensbidrag (Refereegranskat)
    Abstract [en]

    Bulk GaN sliced in bars along (11-20) and (1-100) planes from a boule grown in the [0001] direction by HVPE was confirmed as strain free material with a low dislocation density by using several characterization techniques. The high-structural quality of the material allows photoluminescence studies of free excitons, principal donor bound excitons and their twoelectron satellites with regard to the optical selection rules. Raman scattering study of the bulk GaN with nonpolar orientations allows a direct access to the active phonon modes and a direct determination of their strain-free positions.

  • 342. Peacock, Anna
    et al.
    Campling, Joseph
    Runge, Antoine
    Ren, Haonan
    Shen, Li
    Aktas, Ozan
    Horak, Peter
    Healy, Noel
    Gibson, Ursula
    KTH, Skolan för teknikvetenskap (SCI), Tillämpad fysik, Laserfysik. Norwegian University of Science and Technology, Norway.
    Ballato, John
    Wavelength conversion and supercontinuum generation in silicon optical fibers2017Ingår i: IEEE Journal of Selected Topics in Quantum Electronics, ISSN 1077-260X, E-ISSN 1558-4542, Vol. 24, nr 3Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper describes the state of the art in wavelength conversion and supercontinuum generation using glass-clad silicon core optical fibers. Such semiconductor fibers have enjoyed considerable attention due to their intrinsically high third-order nonlinearities, which are markedly higher than in conventional infrared glasses. Results to date from small core silicon fibers fabricated using both the high-pressure chemical vapor deposition technique and the molten core drawing method are presented. Also discussed are directions for continued study and development, including engineering the dispersion and nonlinear properties as well as improved interconnection.

  • 343.
    Peng, Hao
    et al.
    Shanghai Univ, State Key Lab Adv Special Steels, Shanghai 200072, Peoples R China.;Shanghai Univ, Shanghai Key Lab Adv Ferromet, Shanghai 200072, Peoples R China.;Shanghai Univ, Dept Mat Sci & Engn, Shanghai 200072, Peoples R China..
    Wu, Guangxin
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap. Shanghai Univ, State Key Lab Adv Special Steels, Shanghai 200072, Peoples R China.;Shanghai Univ, Shanghai Key Lab Adv Ferromet, Shanghai 200072, Peoples R China.;Shanghai Univ, Dept Mat Sci & Engn, Shanghai 200072, Peoples R China..
    Peng, Wangjun
    Shanghai Univ, State Key Lab Adv Special Steels, Shanghai 200072, Peoples R China.;Shanghai Univ, Shanghai Key Lab Adv Ferromet, Shanghai 200072, Peoples R China.;Shanghai Univ, Dept Mat Sci & Engn, Shanghai 200072, Peoples R China..
    Cao, Borui
    Meishan Iron & Steel Co, Nanjing 210039, Jiangsu, Peoples R China..
    Zhang, Jieyu
    Shanghai Univ, State Key Lab Adv Special Steels, Shanghai 200072, Peoples R China.;Shanghai Univ, Shanghai Key Lab Adv Ferromet, Shanghai 200072, Peoples R China.;Shanghai Univ, Dept Mat Sci & Engn, Shanghai 200072, Peoples R China..
    The effect of silicon on spangle size in hot-dipped 55 wt%Al-Zn coatings2017Ingår i: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 327, s. 110-117Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The effect of various silicon levels on spangle size in hot-dipped 55 wt%Al-Zn-xSi (x = 0.5, 1.0, 1.6, 2.0, 4.0, all in wt%) coatings was studied. The results showed that as silicon content was increased from 0.5 to 4.0 wt%, spangle size increased gradually from the minimized range to the normal range. Spangle range transition occurred in silicon content between 1.0 and 1.6 wt%. Correlation between intermetallic species and spangle sizes under various silicon contents was investigated. It was found that in the process of spangle size from the minimized to the normal, intermetallic species of the alloy layer were also subject to a regular change of phase transformation from FeAl3 to T-5 (also refers to alpha-AlFeSi), especially remarkable in the range of silicon content where spangle range transited. Phase evolution of the intermetallic layer in various silicon levels was quantitatively analyzed by thermodynamic modelling using Pandat software package, which provided a deep understanding of how the silicon content affect the formation of intermetallic species and controlled the change of intermetallic layer underneath the overlay. First-principles calculations were performed to evaluate the lattice mismatch between intermetallic species and primary alpha-Al, which gave an interpretation of how the intermetallic species influenced the nucleation behavior of primary alpha-Al during solidification and then controlled the spangle size.

  • 344.
    Pettersson, Robert
    KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Human Postures and Movements analysed through Constrained Optimization2009Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Constrained optimization is used to derive human postures and movements. In the first study a static 3D model with 30 muscle groups is used to analyse postures. The activation levels of these muscles are minimized in order to represent the individual's choice of posture. Subject specific data in terms of anthropometry, strength and orthopedic aids serve as input. The aim is to study effects from orthopedic treatment and altered abilities of the subject. Initial validation shows qualitative agreement of posture strategies but further details about passive stiffness and anthropometry are needed, especially to predict pelvis orientation. In the second application, the athletic long jump, a problem formulation is developed to find optimal movements of a multibody system when subjected to contact. The model was based on rigid links, joint actuators and a wobbling mass. The contact to the ground was modelled as a spring-damper system with tuned properties. The movement in the degrees of freedom representing physical joints was described over contact time through two fifth-order polynomials, with a variable transition time, while the motion in the degrees of freedom of contact and wobbling mass was integrated forwards in time, as a consequence. Muscle activation variables were then optimized in order to maximize ballistic flight distance. The optimization determined contact time, end configuration, activation and interaction with the ground from an initial configuration. The results from optimization show a reasonable agreement with experimentally recorded jumps, but individual recordings and measurements are needed for more precise conclusions.

     

  • 345.
    Pirouznia, Pouyan
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Materialteknologi.
    High cycle fatigue properties of stainless martensitic chromium steel springs2012Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    For many materials and components like in high speed trains and airplanes fatigue failures occur in the range of over 107 load cycles which is called the high cycle fatigue range. A modern version of the springs was invented which are applied in a certain application.

    Ultrasonic fatigue testing (20 kHz machine) was conducted for evaluating the steel of the springs. This research explores the fundamental understanding of high cycle fatigue testing of strip steel and assesses a stainless martensitic chromium steel at the high cycle fatigue range. Finite element modeling was conducted to gain knowledge about the effect of various parameters. Significant attention was devoted to the fatigue failure initiations by SEM/EDS.

    The work demonstrated that the method of investigation for high cycle fatigue test is reliable. Fatigue failure at this range was initiated by internal defects which all included non-metallic inclusion. A critical distance was defined Within the strip fatigue specimen where all the fatigue failure initiated. The 3D stress field in the specimen was determined by FEM modeling and the local applied stress at the whole of the flat part of specimen and critical distance was estimated. FEM was also employed to give additional information about the effect of parameters. It was established that damping had the largest influence. The local applied stress of the fatigue test was calculated by means of FEM and SEM analysis. It was used to adjust the S-N curve which resulted in 15% lower values than the nominal applied stress.

  • 346.
    Ponce Valle, Maria Gabriela
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Energi- och ugnsteknik.
    Combustion characteristics of steam-exploded biomass pellets2011Självständigt arbete på avancerad nivå (masterexamen), 80 poäng / 120 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Currently pelletized woody biomass is widely used as a fuel in thermal applications toaccelerate the global transition to renewable energy. Fuel upgrade is one of the key factorsto improve energy conversion processes. Woody biomass can be fractionated into its mainconstituents by steam explosion. Steam-exploded biomass exhibits enhanced heating valueand improves pellet durability. Moreover, there is a significant deviation in thermochemicalbehavior of steam exploded (steam-treated) biomass with respect to the raw material duringpyrolysis.

    This thesis work concerned combustion characteristics of steam-exploded salix. The steamtreatedmaterial was pelletized and combusted under 21% of oxygen with varying thereactor temperature from 500 to 900°C to study the influence of both surrounding andpretreatment conditions during combustion process. The impact of different pretreatmentseverity factors (Ro) on burning behavior was evaluated: mild (205°C-6min, Ro=3.87),intermediate (205°C-12min, Ro=4.17) and severe (228°C-12min, Ro=4.84). Heterogeneousand homogenous ignition mechanisms were observed, which were dependent on the reactortemperature. The ignition time and devolatilization duration were observed independent onpretreatment severity near 900°C, and slightly influenced near 500°C. Enhanceddevolatilization rate was detected with the increment of Ro from 3.87 to 4.17, whilst themost severe pretreatment conditions (Ro=4.84) weakened biomass reactivity duringdevolatilization. Finally, char reactivity was lowered as a result of the increment ofpretreatment severity.

  • 347.
    Pouransari, Zeinab
    KTH, Skolan för teknikvetenskap (SCI), Mekanik, Turbulens.
    Fundamental studies of non-premixed combustion in turbulent wall jets using direct numerical simulation2011Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The present thesis deals with the fundamental aspects of turbulent mixingand non-premixed combustion in wall-jet flows. Direct numerical simulations(DNS) of compressible turbulent flows are performed in a wall-jet configura-tion, which has a close resemblance to many industrial combustion applica-tions. The triple ”turbulence-chemistry-wall” interactions are also present inthis flow set-up. These interactions have been addressed by first focusing onturbulent flow effects on the isothermal reaction, including the near-wall issues.Then, by adding heat-release to the simulations, it has been concentrated onheat-release effects on various phenomena that occur in the reacting turbulentwall-jet flow. In the computational domain, fuel and oxidizer enter separatelyin a non-premixed manner and the flow is fully turbulent and subsonic in allsimulations. In the first phase of this study, the case of a turbulent wall-jetincluding an isothermal reaction without heat release is addressed in order toisolate the near-wall effects and the mixing characteristics of the flow and thekey statistics for combustion are studied in the absence of thermal effects. Adeeper insight into three-dimensional mixing and reaction characteristics in aturbulent wall-jet has been gained through investigation of the probability den-sity functions, higher order moments of velocities and reacting scalars and thescalar dissipation rates of different species. In the second phase, DNS of turbu-lent reacting wall-jets including heat release is performed, where a single-stepglobal exothermic reaction with an Arrhenius-type reaction rate is considered.The main target was to identify the heat-release effects on different mixingscales of turbulent wall-jet flow. The scalar dissipation rates, time scale ratios,two-point correlations, one and two-dimensional premultiplied spectra are usedto illustrate the heat release induced modifications. It is observed that heatrelease effects delay the transition process in the chemically reacting cases andenlarge the fluctuation intensities of density and pressure, but have a dampingeffect on all velocity fluctuation intensities. Finer small mixing scales were ob-served in the isothermal simulations and larger vortical structures formed afteradding significant amounts of heat-release. Simulations with different Damk ̈h-  oler numbers, but comparable temperature-rise are performed and the expectedbehavior, a thinner flame with increasing Damk ̈hler number, is observed. Finally, some heat transfer related quantities are examined. The wall heat fluxand the corresponding Nusselt numbers are addressed. The near-wall reactioneffects on the skin friction coefficient are studied and further the reaction char-acteristics are investigated throughout the domain.

  • 348.
    Pouransari, Zeinab
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Brethouwer, Geert
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Johansson, Arne J.
    KTH, Skolan för teknikvetenskap (SCI), Mekanik. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Direct numerical simulation of an isothermal reacting turbulent wall-jet2011Ingår i: Physics of fluids, ISSN 1070-6631, E-ISSN 1089-7666, Vol. 23, nr 8, s. 085104-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In the present investigation, Direct Numerical Simulation (DNS) is used to study a binary irreversible and isothermal reaction in a plane turbulent wall-jet. The flow is compressible and a single-step global reaction between an oxidizer and a fuel species is solved. The inlet based Reynolds, Schmidt, and Mach numbers of the wall-jet are Re = 2000, Sc = 0.72, and M = 0.5, respectively, and a constant coflow velocity is applied above the jet. At the inlet, fuel and oxidizer enter the domain separately in a non-premixed manner. The turbulent structures of the velocity field show the common streaky patterns near the wall, while a somewhat patchy or spotty pattern is observed for the scalars and the reaction rate fluctuations in the near-wall region. The reaction mainly occurs in the upper shear layer in thin highly convoluted reaction zones, but it also takes place close to the wall. Analysis of turbulence and reaction statistics confirms the observations in the instantaneous snapshots, regarding the intermittent character of the reaction rate near the wall. A detailed study of the probability density functions of the reacting scalars and comparison to that of the passive scalar throughout the domain reveals the significance of the reaction influence as well as the wall effects on the scalar distributions. The higher order moments of both the velocities and the scalar concentrations are analyzed and show a satisfactory agreement with experiments. The simulations show that the reaction can both enhance and reduce the dissipation of fuel scalar, since there are two competing effects; on the one hand, the reaction causes sharper scalar gradients and thus a higher dissipation rate, on the other hand, the reaction consumes the fuel scalar thereby reducing the scalar dissipation.

  • 349.
    Pouransari, Zeinab
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Johansson, Arne V.
    KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Heat release effects on mixing scales of turbulent reacting wall-jets: a direct numerical simulation studyManuskript (preprint) (Övrigt vetenskapligt)
  • 350.
    Pouransari, Zeinab
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Johansson, Arne V.
    KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Numerical investigation of wall heat transfer and skin-friction coefficient in reacting turbulent wall-jetsManuskript (preprint) (Övrigt vetenskapligt)
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