4,146 research outputs found
Approaching a reliable process simulation for the virtual product development
In this paper an outline for a strategy to include manufacturing effects in subsequent\ud
simulations for the virtual product development from an industrial point of view is given.\ud
Especially the conditions for a successful mapping of geometry and results between\ud
different applications are discussed. An example shows the significance of the inclusion\ud
of previous simulations in the final assessment of a part
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First CRDS-measurements of water vapour continuum in the 940nm absorption band
Measurements of near-infrared water vapour continuum using continuous wave cavity ring down spectroscopy (cw-
CRDS) have been performed at around 10611.6 and 10685:2 cm1. The continuum absorption coefficients for N2-
broadening have been determined for two temperatures and wavenumbers.
These results represent the first near-IR continuum laboratory data determined within the complex spectral environment in the 940nm water vapour band and are in reasonable agreement with simulations using the semiempirical CKD formulation
Centenary of the Birth of V.A. Obruchev, Soviet Geologist, Geographer, Traveller, and Pioneer in Permafrost Research
Vladimir Afanas'evich Obruchev, who was born on October 10, 1863 in the village of Klepenino in the upper Volga region, was an outstanding natural scientist, who made great contributions to the exploration of Asia. His father was in the military service and often transferred with his family from one province to another. For some time they lived in Lithuania where Obruchev completed his high school education in Vilnius in 1881 and then passed the entrance examinations of both the Mining and the Technological institutes in Petersburg. He chose the Mining Institute and completed his studies there in 1886. ... For his great achievements the Academy of Sciences of the USSR named Obruchev a corresponding member of the Academy in 1921, and an active member in 1929. From this time on he was working in the Academy of Sciences and for 3 years, beginning in 1929, he was director of the Geological Institute. During World War II he was Academician-secretary of the Department of Geological and Geographical Sciences and as such led the scientific research of all academic institutes in this field. Obruchev was among the first to advocate the organization of a special committee for the study of permafrost. He was president of this committee from 1930 to 1939. In this year he became director of the Permafrost Institute, which now bears his name, and held that position for the rest of his life. ... He was also deeply involved in the exploration of northern regions. While analysing the geology of the greater part of Asia north of the Arctic Circle he concluded that during Quaternary times two glacial periods had occurred there, and that a thick ice sheet had covered not only the arctic zone but had extended south to 60°N. He established that at the beginning of the Quaternary dry land occupied the present Kara Sea area and that glaciers extended from there to the south between the Urals and the Taymyr Peninsula, which were also covered by a continental ice sheet at that time. Obruchev thought that the present Greenland ice cap and other glaciers of the North American islands, the glaciers of Spitsbergen, Zemlya Frantsa Iosifa, Novaya Zemlya, and Severnaya Zemlya are the remnants of ice caps and glaciers of the Ice Ages. Further evidence for the glaciations is the existence of fossil ice, which Obruchev discussed in detail in several of his works. His research concerning the Ice Ages helped to establish the southern limits of glaciation and the present distribution of permafrost. The very large amount of geological and geographical information collected by Obruchev in northern Asia has very great value in permafrost research, especially in the preparation of long-term climatic predictions and in the determination of the degree of climatic amelioration in the Arctic. He did not isolate permafrost from other natural phenomena but studied it in relation to the geology of the region. ... Obruchev died on June 19, 1956 and was buried in the Novodevich' cemetery in Moscow
CALCULATION OF NEUTRON-CAPTURE REACTIONS CONTRIBUTION TO ENERGY RELEASE IN VVER-1000 USING SERPENT CODE
Calculating the energy release in fuel elements is an important aspect of the modeling and design of nuclear reactors. Most of the energy is produced by fission, but a non-negligible percentage is coming from neutron capture reactions, such as (n, γ) or (n, α). We implement a previously developed method for the calculation of effective energy release using Serpent Monte Carlo code. We investigate the percentage of capture component in effective energy release for various models of VVER-1000 fuel: firstly, an equivalent cell, then fresh fuel assemblies of different compositions, differing in fuel enrichment and the presence of burnable absorbers. The results are compared to similar calculations previously done in MCNP 4 and MCU 5
Lipschitz shadowing implies structural stability
We show that the Lipschitz shadowing property of a diffeomorphism is
equivalent to structural stability. As a corollary, we show that an expansive
diffeomorphism having the Lipschitz shadowing property is Anosov.Comment: 11 page
Optimal polymer slugs injection curves
In the paper we study miscible injection of liquids with decreasing viscosity
in two-dimensional geometry. Polymer flooding of oil fields is our prototype
model. Based on several one-dimensional approximate models we give rigorous
formulation of the graded viscosity banks (GVB) technology which helps to save
polymer by injecting several slugs with gradual decrease of viscosity instead
of one slug. Limiting injection curves when number of slugs tends to infinity
is calculated
Modeling of optical properties of hybrid metal-organic nanostructures
To model spectral characteristics of hybrid metal-organic nanostructures, the extended Mie theory was used, which makes it possible to calculate the extinction efficiency factor (Qext) and the scattering efficiency factor in the near zone (QNF) of two-layer spherical particles placed in an absorbing matrix. Two-layer plasmon nanospheres consisting of a metallic core (Ag, Cu) coated with dielectric shells and located into the copper phthalocyanine (CuPc) matrix were considered. The influence of dielectric shell thickness and refractive index on the characteristics of the surface plasmon resonance of absorption (SPRA) was studied. The possibility of the SPRA band tuning by changing the optical and geometrical parameters of dielectric shells was shown. It was established that dielectric shells allow to shift the surface plasmon resonance band of plasmonic nanoparticles absorption both to short- and long-wavelength spectral range depending on the relation between shell and matrix refractive indexes.To model spectral characteristics of hybrid metal-organic nanostructures, the extended Mie theory was used, which makes it possible to calculate the extinction efficiency factor (Qext) and the scattering efficiency factor in the near zone (QNF) of two-layer spherical particles placed in an absorbing matrix. Two-layer plasmon nanospheres consisting of a metallic core (Ag, Cu) coated with dielectric shells and located into the copper phthalocyanine (CuPc) matrix were considered. The influence of dielectric shell thickness and refractive index on the characteristics of the surface plasmon resonance of absorption (SPRA) was studied. The possibility of the SPRA band tuning by changing the optical and geometrical parameters of dielectric shells was shown. It was established that dielectric shells allow to shift the surface plasmon resonance band of plasmonic nanoparticles absorption both to short- and long-wavelength spectral range depending on the relation between shell and matrix refractive indexes
Local Ferroelectricity in SrTiO_3 Thin Films
The temperature-dependent polarization of SrTiO_3 thin films is investigated
using confocal scanning optical microscopy. A homogeneous out-of-plane and
inhomogeneous in-plane ferroelectric phase are identified from images of the
linear electrooptic response. Both hysteretic and non-hysteretic behavior are
observed under a dc bias field. Unlike classical transitions in bulk
ferroelectrics, local ferroelectricity is observed at temperatures far above
the dielectric permittivity maximum. The results demonstrate the utility of
local probe experiments in understanding inhomogeneous ferroelectrics.Comment: 8 pages, 3 figures, accepted for publication in PR
Widespread erosion on high plateaus during recent glaciations in Scandinavia
Glaciers create some of Earth’s steepest topography; yet, many areas that were repeatedly overridden by ice sheets in the last few million years include extensive plateaus. The distinct geomorphic contrast between plateaus and the glacial troughs that dissect them has sustained two long-held hypotheses: first, that ice sheets perform insignificant erosion beyond glacial troughs, and, second, that the plateaus represent ancient pre-glacial landforms bearing information of tectonic and geomorphic history prior to Pliocene–Pleistocene global cooling (~3.5 Myr ago). Here we show that the Fennoscandian ice sheets drove widespread erosion across plateaus far beyond glacial troughs. We apply inverse modelling to 118 new cosmogenic 10Be and 26Al measurements to quantify ice sheet erosion on the plateaus fringing the Sognefjorden glacial trough in western Norway. Our findings demonstrate substantial modification of the pre-glacial landscape during the Quaternary, and that glacial erosion of plateaus is important when estimating the global sediment flux to the oceans
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