| 1. |
- Bentham, James, et al.
(author)
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A century of trends in adult human height
- 2016
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In: eLIFE. - : eLife Sciences Publications Ltd. - 2050-084X. ; 5
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Journal article (peer-reviewed)abstract
- Being taller is associated with enhanced longevity, and higher education and earnings. We reanalysed 1472 population-based studies, with measurement of height on more than 18.6 million participants to estimate mean height for people born between 1896 and 1996 in 200 countries. The largest gain in adult height over the past century has occurred in South Korean women and Iranian men, who became 20.2 cm (95% credible interval 17.5–22.7) and 16.5 cm (13.3– 19.7) taller, respectively. In contrast, there was little change in adult height in some sub-Saharan African countries and in South Asia over the century of analysis. The tallest people over these 100 years are men born in the Netherlands in the last quarter of 20th century, whose average heights surpassed 182.5 cm, and the shortest were women born in Guatemala in 1896 (140.3 cm; 135.8– 144.8). The height differential between the tallest and shortest populations was 19-20 cm a century ago, and has remained the same for women and increased for men a century later despite substantial changes in the ranking of countries.
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| 2. |
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| 3. |
- Unsalan, Ozan, et al.
(author)
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The Sariçiçek howardite fall in Turkey : Source crater of HED meteorites on Vesta and impact risk of Vestoids
- 2019
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In: Meteoritics and Planetary Science. - Hoboken : John Wiley & Sons. - 1086-9379 .- 1945-5100. ; 54:5, s. 953-1008
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Journal article (peer-reviewed)abstract
- The Sariçiçek howardite meteorite shower consisting of 343 documented stones occurred on September 2, 2015 in Turkey and is the first documented howardite fall. Cosmogenic isotopes show that Sariçiçek experienced a complex cosmic‐ray exposure history, exposed during ~12–14 Ma in a regolith near the surface of a parent asteroid, and that an ~1 m sized meteoroid was launched by an impact 22 ± 2 Ma ago to Earth (as did one‐third of all HED meteorites). SIMS dating of zircon and baddeleyite yielded 4550.4 ± 2.5 Ma and 4553 ± 8.8 Ma crystallization ages for the basaltic magma clasts. The apatite U‐Pb age of 4525 ± 17 Ma, K‐Ar age of ~3.9 Ga, and the U,Th‐He ages of 1.8 ± 0.7 and 2.6 ± 0.3 Ga are interpreted to represent thermal metamorphic and impact‐related resetting ages, respectively. Petrographic; geochemical; and O‐, Cr‐, and Ti‐isotopic studies confirm that Sariçiçek belongs to the normal clan of HED meteorites. Petrographic observations and analysis of organic material indicate a small portion of carbonaceous chondrite material in the Sariçiçek regolith and organic contamination of the meteorite after a few days on soil. Video observations of the fall show an atmospheric entry at 17.3 ± 0.8 km s−1 from NW; fragmentations at 37, 33, 31, and 27 km altitude; and provide a pre‐atmospheric orbit that is the first dynamical link between the normal HED meteorite clan and the inner Main Belt. Spectral data indicate the similarity of Sariçiçek with the Vesta asteroid family (V‐class) spectra, a group of asteroids stretching to delivery resonances, which includes (4) Vesta. Dynamical modeling of meteoroid delivery to Earth shows that the complete disruption of a ~1 km sized Vesta family asteroid or a ~10 km sized impact crater on Vesta is required to provide sufficient meteoroids ≤4 m in size to account for the influx of meteorites from this HED clan. The 16.7 km diameter Antionia impact crater on Vesta was formed on terrain of the same age as given by the 4He retention age of Sariçiçek. Lunar scaling for crater production to crater counts of its ejecta blanket show it was formed ~22 Ma ago.
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| 4. |
- Bader, Alexander, et al.
(author)
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Proton Temperature Anisotropies in the Plasma Environment of Venus
- 2019
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In: Journal of Geophysical Research - Space Physics. - : American Geophysical Union (AGU). - 2169-9380 .- 2169-9402. ; 124:5, s. 3312-3330
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Journal article (peer-reviewed)abstract
- Velocity distribution functions (VDFs) are a key to understanding the interplay between particles and waves in a plasma. Any deviation from an isotropic Maxwellian distribution may be unstable and result in wave generation. Using data from the ion mass spectrometer IMA (Ion Mass Analyzer) and the magnetometer (MAG) onboard Venus Express, we study proton distributions in the plasma environment of Venus. We focus on the temperature anisotropy, that is, the ratio between the proton temperature perpendicular (T-perpendicular to) and parallel (T-parallel to) to the background magnetic field. We calculate average values of T-perpendicular to and T-parallel to for different spatial areas around Venus. In addition we present spatial maps of the average of the two temperatures and of their average ratio. Our results show that the proton distributions in the solar wind are quite isotropic, while at the bow shock stronger perpendicular than parallel heating makes the downstream VDFs slightly anisotropic (T-perpendicular to/T-parallel to > 1) and possibly unstable to generation of proton cyclotron waves or mirror mode waves. Both wave modes have previously been observed in Venus's magnetosheath. The perpendicular heating is strongest in the near-subsolar magnetosheath (T-perpendicular to/ T-parallel to approximate to 3/2), which is also where mirror mode waves are most frequently observed. We believe that the mirror mode waves observed here are indeed generated by the anisotropy. In the magnetotail we observe planetary protons with largely isotropic VDFs, originating from Venus's ionosphere.
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| 5. |
- Bunaziv, I., et al.
(author)
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Application of laser-arc hybrid welding of steel for low-temperature service
- 2019
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In: The International Journal of Advanced Manufacturing Technology. - : Springer. - 0268-3768 .- 1433-3015. ; 102:5-8, s. 2601-2613
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Journal article (peer-reviewed)abstract
- Laser-arc hybrid welding (LAHW) is more often used in shipbuilding and oil and gas industries in recent years. Its popularity arises due to many advantages compared to conventional arc welding processes. The laser beam source is used to achieve much higher penetration depths. By adding filler wire to the process area, by means of an arc source, the mechanical properties can be improved, e.g. higher toughness at low temperatures. Therefore, LAHW is a perspective process for low-temperature service. Applicability of LAHW is under concern due to process stability and mechanical properties related to heterogeneous filler wire distribution through the whole weld metal in deep and narrow joints. This can cause reduced mechanical properties in the weld root as well as problems with solidification cracking. The fast cooling rate in the root provides hard and brittle microconstituents lowering toughness at low temperatures. Numerical simulations and experimental observations showed that an increase in heat input from the laser beam is an effective way to reduce the cooling rate, which is also possible by applying preheating.
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| 6. |
- Bunaziv, Ivan, et al.
(author)
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Deep penetration fiber laser-arc hybrid welding of thick HSLA steel
- 2018
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In: Journal of Materials Processing Technology. - : Elsevier. - 0924-0136 .- 1873-4774. ; 256, s. 216-228
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Journal article (peer-reviewed)abstract
- The present investigation addresses laser-arc hybrid welding of 45 mm thick steel with variation in a wide range of process parameters. High volume fraction of acicular ferrite formed in the upper part of the weld metal regardless process parameters. Significantly lower fraction of acicular ferrite was found in the root due to substantially increased cooling rates and the inability to deliver filler wire to this region, resulting in bainite-martensite microstructures in the root. The delivery of filler wire to the root can be enhanced by increasing the air gap between the plates. Higher heat inputs reduce cooling rates in the root which create softer and ductile microstructures, at the expense of a much wider and coarser grained HAZ. The results obtained showed high fusion line and weld metal toughness at low temperature (−50 °C).
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| 7. |
- Bunaziv, Ivan, et al.
(author)
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Hybrid Welding of 45 mm High Strength Steel Sections
- 2017
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In: Physics Procedia. - : Elsevier. - 1875-3892. ; 89, s. 11-22
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Journal article (peer-reviewed)abstract
- Thick section welding has significant importance for oil and gas industry in low temperature regions. Arc welding is usually employed providing suitable quality joints with acceptable toughness at low temperatures with very limited productivity compared to modern high power laser systems. Laser-arc hybrid welding (LAHW) can enhance the productivity by several times due to higher penetration depth from laser beam and combined advantages of both heat sources. LAHW was applied to join 45 mm high strength steel with double-sided technique and application of metal cored wire. The process was captured by high speed camera, allowing process observation in order to identify the relation of the process stability on weld imperfections and efficiency. Among the results, it was found that both arc power and presence of a gap increased penetration depth, and that higher welding speeds cause unstable processing and limits penetration depth. Over a wide range of heat inputs, the welds where found to consist of large amounts of fine-grained acicular ferrite in the upper 60-75% part of welds. At the root filler wire mixing was less and cooling faster, and thus found to have bainitic transformation. Toughness of deposited welds provided acceptable toughness at -50 °C with some scattering.
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| 8. |
- Bunaziv, Ivan, et al.
(author)
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Laser-arc hybrid welding of thick HSLA steel
- 2018
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In: Journal of Materials Processing Technology. - : Elsevier. - 0924-0136 .- 1873-4774. ; 259, s. 75-87
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Journal article (peer-reviewed)abstract
- A standard laser-arc hybrid welding (S-LAHW) and LAHW with preplaced cut wire inside the groove before welding were studied and compared. The S-LAHW setup revealed problems with filler wire delivery to the root, resulting in substantial hardness increase due to bainitic-martensitic transformation. The applied finite element modelling confirmed significant cooling rate increase in the root area for deep penetration welds. Preplacement of cut wire prior to welding reduced hardness providing improved welds with higher homogeneity. This method was subsequently applied for multi-pass welding that revealed insufficient nucleation of acicular ferrite on non-metallic inclusions (NMIs). It is implied that a critical cooling rate has been exceeded where the NMIs become inactive, resulting in a microstructure consisting of a martensite and bainite mixture. This kind of microstructure is clearly harmful for the weld metal toughness.
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| 9. |
- Bunaziv, Ivan, et al.
(author)
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Porosity and solidification cracking in welded 45 mm thick steel by fiber laser-MAG process
- 2019
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In: Procedia Manufacturing. - : Elsevier. - 2351-9789. ; 36, s. 101-111
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Journal article (peer-reviewed)abstract
- Porosity and solidification cracking in joining of thick sections are very common issues in deep penetration keyhole laser-arc hybrid welding (LAHW). In the present work, 45 mm thick high strength steel was joined by a double-sided technique. With combined use of fast welding speeds and larger air gap between plates, higher amount of porosity was found because of the dynamic behavior of the keyhole walls. Solidification cracking formed at the centerline in the bottom of the weld due to high-depth-to-width geometrical ratio. Numerical simulations have been performed and showed very high cooling rate and stresses occurred in the root of the deep welds, which corresponds with higher cracking tendency.
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| 10. |
- Bunaziv, Ivan, et al.
(author)
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Process stability during fiber laser-arc hybrid welding of thick steel plates
- 2018
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In: Optics and lasers in engineering. - : Elsevier. - 0143-8166 .- 1873-0302. ; 102, s. 34-44
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Journal article (peer-reviewed)abstract
- TThick steel plates are frequently used in shipbuilding, pipelines and other related heavy industries, and are usually joined by arc welding. Deep penetration laser-arc hybrid welding could increase productivity but has not been thoroughly investigated, and is therefore usually limited to applications with medium thickness (5-15 mm) sections. A major concern is process stability, especially when using modern welding consumables such as metal-cored wire and advanced welding equipment. High speed imaging allows direct observation of the process so that process behavior and phenomena can be studied. In this paper, 45 mm thick high strength steel was welded (butt joint double-sided) using the fiber laser-MAG hybrid process utilizing a metal-cored wire without pre-heating. Process stability was monitored under a wide range of welding parameters. It was found that the technique can be used successfully to weld thick sections with appropriate quality when the parameters are optimized. When comparing conventional pulsed and the more advanced cold metal transfer pulse (CMT+P) arc modes, it was found that both can provide high quality welds. CMT+P arc mode can provide more stable droplet transfer over a limited range of travel speeds. At higher travel speeds, an unstable metal transfer mechanism was observed. Comparing leading arc and trailing arc arrangements, the leading arc configuration can provide higher quality welds and more stable processing at longer inter-distances between the heat sources.
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