| 1. |
- Airiskallio, E., et al.
(författare)
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Magnetic origin of the chemical balance in alloyed Fe-Cr stainless steels : First-principles and Ising model study
- 2014
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Ingår i: Computational materials science. - : Elsevier BV. - 0927-0256 .- 1879-0801. ; 92, s. 135-140
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Tidskriftsartikel (refereegranskat)abstract
- Iron-chromium is the base material for most of the stainless steel grades. Recently, new insights into the origins of fundamental physical and chemical characteristics of Fe-Cr based alloys have been achieved. Some of the new results are quite unexpected and call for further investigations. The present study focuses on the magnetic contribution in the atomic driving forces related to the chemical composition in Fe-Cr when alloyed with Al, Ti, V, Mn, Co, Ni, and Mo. Using the ab initio exact muffin-tin orbitals method combined with an Ising-type spin model, we demonstrate that the magnetic moment of the solute atoms with the induced changes in the magnetic moments of the host atoms form the main factor in determining the mixing energy and chemical potentials of low-Cr Fe-Cr based alloys. The results obtained in the present work are related to the designing and tuning of the microstructure and corrosion protection of low-Cr steels.
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| 2. |
- Nurmi, E., et al.
(författare)
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Directional Young's modulus of single-crystal and cold-rolled titanium from ab initio calculations : Preferred crystal orientation due to cold rolling
- 2016
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Ingår i: Philosophical Magazine. - : Taylor & Francis. - 1478-6435 .- 1478-6443. ; 96:26, s. 2736-2751
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Tidskriftsartikel (refereegranskat)abstract
- Titanium is a strong, corrosion resistant metal with low mass density, making it ideal for various purposes, including aviation and medical applications. In the present work, the elastic properties of titanium have been investigated using the first principles Exact Muffin-Tin Orbitals method. The focus of our study is the anisotropic elasticity of single-crystal and cold-rolled titanium. Both types of titanium are used in industrial applications because of their special mechanical properties compared to randomly ordered polycrystalline alloys. Single crystals have better creep resistance compared to polycrystalline metals, while cold-rolled ones, on the other hand, possess more strength. Here cold-rolled titanium is investigated for the first time using ab initio calculations. Single-crystal results are obtained directly from first principles total energy calculations, whereas the elasticity of the cold-rolled structure is estimated from the single-crystal data. The elasticity of cold-rolled titanium has previously been investigated only experimentally, and thus the present computational approach provides new insight and valuable complementary information, not only for cold-rolled titanium, but also for more complex structures. Our results are found to be in good agreement with experimental findings and therefore serve as a starting point for investigating the elasticity of titanium alloys, which, using our method, can be accomplished as easily as the pure titanium case.
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| 3. |
- Lohan, E.S., et al.
(författare)
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MULTI-POS: Lessons learnt from fellows and supervisors
- 2017
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Ingår i: Multi-Technology Positioning. - Cham : Springer International Publishing. - 9783319504261 ; , s. 323-329
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- The path to a successful and cooperative network is not always smooth. Marie Curie networks are, by definition, networks of people with various technical and cultural backgrounds and with different personalities, individual work and life targets, and personal ways of solving the challenges that each has to cope with. The larger a network is, the more likely it is that some conflicts or personality mismatches appear, but this is not necessarily a bad thing, and it can be used as a learning and growth lesson. This chapter addresses the various challenges that were encountered during the MULTI-POS implementation and it summarizes the lessons learnt by both the fellows and the supervisors. The goal of this chapter is to offer some generic guidelines in forming and running large international networks, such as the Marie Curie training networks, and to enable the people interested in such collaborations to pro-actively identify and tackle some of the inherent challenges in such networks.
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| 4. |
- Nurmi, J, et al.
(författare)
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The SoC-mobinet model in system-on-chip education
- 2005
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Ingår i: 2005 IEEE International Conference on Microelectronic Systems Education, Proceedings. - LOS ALAMITOS, CA : IEEE COMPUTER SOC. - 0769523749 ; , s. 71-72
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Konferensbidrag (refereegranskat)abstract
- This paper describes the model of developing SoC curricula jointly by industry and academia, where joint effort research results are turned into course contents for SoC-curricula and industry training activities.
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| 5. |
- Ferrara, N.G., et al.
(författare)
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A comparison of Bayesian localization methods in the presence of outliers
- 2017
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Ingår i: 2017 13th International Wireless Communications and Mobile Computing Conference, IWCMC 2017. ; , s. 1546-1551
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Konferensbidrag (refereegranskat)abstract
- Localization of a user in a wireless network is challenging in the presence of malfunctioning or malicious reference nodes, since if they are not accounted for, large localization errors can ensue. We evaluate three Bayesian methods to statistically identify outliers during localization: an exact method, an expectation maximization (EM) method proposed earlier, and a new method based on Variational Bayesian EM (VBEM). Simulation results indicate similar performance for the latter two schemes, with the VBEM algorithm able to provide a statistical description of the user location, rather than an estimate as in the simpler EM case. In contrast to previous studies, we find that there is a significant gap between the approximate methods and the exact method, the cause of which is discussed.
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| 6. |
- Heinonen, M. H., et al.
(författare)
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Initial Oxidation of Fe-Al and Fe-Cr-Al Alloys : Cr as an Alumina Booster
- 2011
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Ingår i: Oxidation of Metals. - : Springer Science and Business Media LLC. - 0030-770X .- 1573-4889. ; 76:3-4, s. 331-346
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Tidskriftsartikel (refereegranskat)abstract
- The boosting effect of Cr on the growth of the protective alumina scale on Fe-Al alloys is investigated by X-ray photoelectron spectroscopy. Using low oxygen pressure the surface chemistry of the alloys is monitored starting from the first moments of oxidation. Chromium affects the Fe/Al surface-bulk exchange which is clearly detected by analyzing the measured surface concentrations within the atomic concentration models. Experimental results presented are in good agreement with the previous ones obtained by experiments at ambient conditions and ab initio calculations.
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| 7. |
- Lagerspetz, E., et al.
(författare)
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Pervasive Communities in the Internet of People
- 2018
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Ingår i: 2018 IEEE International Conference on Pervasive Computing and Communications Workshops, PerCom Workshops 2018. - : Institute of Electrical and Electronics Engineers Inc.. - 9781538632277 ; , s. 40-45
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Konferensbidrag (refereegranskat)abstract
- The Internet has traditionally been a device-oriented architecture where devices with IP addresses are first-class citizens, able to serve and consume content or services, and their owners take part in the interaction only through those devices. The Internet of People (IoP) is a recent paradigm where devices become proxies of their users, and can act on their behalf. To realize IoP, new policies and rules for how devices can take actions are required. The role of context information grows as devices act autonomously based on the environment and existing social relationships between their owners. In addition, the social profiles of device owners determine e.g. how altruistic or resourceconserving they are in collaborative computing scenarios. In this paper we focus on community formation in IoP, a prerequisite for enabling collaborative scenarios, and discuss main challenges and propose potential solutions. © 2018 IEEE.
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| 8. |
- Lohan, E.S., et al.
(författare)
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Conclusions
- 2017
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Ingår i: Multi-Technology Positioning. - Cham : Springer International Publishing. - 9783319504278 ; , s. 331-332
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Navigation and localization are nowadays an intrinsic part of the majority of wireless communication devices. They are also likely to play crucial roles in the new generations of communication devices, such as Device-to-Device (D2D), Internet of Things (IoT) and 5G.
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| 9. |
- Nurmi, E., et al.
(författare)
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Assessing the elastic properties and ductility of Fe-Cr-Al alloys from ab initio calculations
- 2016
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Ingår i: Philosophical Magazine. - : Taylor & Francis. - 1478-6435 .- 1478-6443. ; 96:2, s. 122-133
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Tidskriftsartikel (refereegranskat)abstract
- Fe-Al is one of the best corrosion resistant alloys at high temperatures. The flip side of Al addition to Fe is the deterioration of the mechanical properties. This problem can be solved by adding a suitable amount of third alloying component. In the present work, we use ab initio calculations based on density functional theory to study the elastic properties of Fe1-x-yCrxAly alloys for Al and Cr contents up to 20 at.%. We assess the ductility as a function of chemistry by making use of the semi-empirical correlations between the elastic parameters and mechanical properties. In particular, we derive the bulk modulus to shear modulus ratio and the Cauchy pressure and monitor their trends in terms of chemical composition. The present findings are contrasted with the previously established oxidation resistance of Fe-Cr-Al alloys.
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