Search results for "boundary"
showing 10 items of 1626 documents
Symmetric BEM Formulations for Elastic-Damage Material Models
1997
BEM analysis for elastic-damage materials is addressed by “undamaged” fundamental solutions. In step-by-step analysis, the actual response is obtained by an iterative procedure in which the undamaged structure is subjected to the loads and to some fictitious strains (or relaxation stresses) simulating the damage effects. Through symmetric BEM, the solution to the typical iteration problem is shown to solve a boundary/domain stationarity principle, whereas the above iterative procedure can be incorporated in a predictor/corrector scheme aimed at the integration of the damage laws. Discretization by boundary and interior elements leads to a symmetric equation system.
Deformation of melt-bearing systems—insight from in situ grain-scale analogue experiments
2005
Abstract The deformation behaviour of partially molten rocks was investigated using in situ analogue experiments with norcamphor+ethanol, as well as partially molten KNO 3 +LiNO 3 . Three general deformation regimes could be distinguished during bulk pure shear deformation. In regime I, above ca. 8–10 vol.% liquid (melt) fraction ( ϕ bulk ), deformation is by compaction, distributed granular flow, and grain boundary sliding (GBS). At ϕ bulk ϕ bulk (regime III), grains form a coherent framework that deforms by grain boundary migration accommodated dislocation creep, associated with efficient segregation of remaining liquid. The transition liquid fraction between regimes I and II ( ϕ LT ) dep…
Influence of a nano phase segregation on the thermoelectric properties of the p-type doped stannite compound Cu(2+x)Zn(1-x)GeSe4.
2012
Engineering nanostructure in bulk thermoelectric materials has recently been established as an effective approach to scatter phonons, reducing the phonon mean free path, without simultaneously decreasing the electron mean free path for an improvement of the performance of thermoelectric materials. Herein the synthesis, phase stability, and thermoelectric properties of the solid solutions Cu_(2+x)Zn_(1–x)GeSe_4 (x = 0–0.1) are reported. The substitution of Zn^(2+) with Cu^+ introduces holes as charge carriers in the system and results in an enhancement of the thermoelectric efficiency. Nano-sized impurities formed via phase segregation at higher dopant contents have been identified and are l…
Non-Monotonic Concentration Dependence of the Electro-Phoretic Mobility of Charged Spheres in Realistic Salt Free Suspensions
2020
Using super-heterodyne Doppler velocimetry with multiple scattering correction, we extend the opti-cally accessible range of concentrations in experiments on colloidal electro-kinetics. We here meas-ured the electro-phoretic mobility and the DC conductivity of aqueous charged sphere suspensions covering about three orders of magnitude in particle concentrations and transmissions as low as 40%. The extended concentration range for the first time allows the demonstration of a non-monotonic con-centration dependence of the mobility for a single particle species. Our observations reconcile previ-ous experimental observations made on other species over restricted concentration ranges. We com-par…
Forward rapidity isolated photon production in proton-nucleus collisions
2018
We calculate isolated photon production at forward rapidities in proton-nucleus collisions in the Color Glass Condensate framework. Our calculation uses dipole cross sections solved from the running coupling Balitsky-Kovchegov equation with an initial condition fit to deep inelastic scattering data and extended to nuclei with an optical Glauber procedure that introduces no additional parameters beyond the basic nuclear geometry. We present predictions for future forward RHIC and LHC measurements. The predictions are also compared to updated results for the nuclear modification factors for pion production, Drell-Yan dileptons and $J/\psi$ mesons in the same forward kinematics, consistently c…
Magnētiskā šķidruma pilieni rotējošā laukā: teorija, eksperimenti un simulācijas
2022
Magnētiskā šķidruma pilieni ir reizē deformējami un ietekmējami ar ārējo magnētisko lauku, kas tos padara par interesantu materiālu, kas is atradis daudzus pielietojumus mikrofluīdikā. Šajā darbā tiek aplūkota šādu pilienu dinamika rotējošā magnētiskajā laukā. Pilieni tiek pētīti, izmantojot vairākas pieejas - teorētiski, eksperimentāli un izmantojot simulācijas. Kad rotējošais magnētiskais lauks lauks ir vājš un piliena deformācija ir maza, piliena kustība tiek aprēķināta analītiski. Konstatēts, ka piliena formas attīstību laikā regulē trīs nelineāru diferenciālvienādojumu sistēma. Mazo deformāciju tuvinājumā piliena uzvedību kvalitatīvi raksturo viens parametrs, kas ir proporcionāls kapil…
Short chaotic strings and their behaviour in the scaling region
2008
Coupled map lattices are a paradigm of higher-dimensional dynamical systems exhibiting spatio-temporal chaos. A special case of non-hyperbolic maps are one-dimensional map lattices of coupled Chebyshev maps with periodic boundary conditions, called chaotic strings. In this short note we show that the fine structure of the self energy of this chaotic string in the scaling region (i.e. for very small coupling) is retained if we reduce the length of the string to three lattice points.
Trace gas composition in the Asian summer monsoon anticyclone: a case study based on aircraft observations and model simulations
2017
We present in situ measurements of the trace gas composition of the upper tropospheric (UT) Asian summer monsoon anticyclone (ASMA) performed with the High Altitude and Long Range Research Aircraft (HALO) in the frame of the Earth System Model Validation (ESMVal) campaign. Air masses with enhanced O3 mixing ratios were encountered after entering the ASMA at its southern edge at about 150 hPa on 18 September 2012. This is in contrast to the presumption that the anticyclone's interior is dominated by recently uplifted air with low O3 in the monsoon season. We also observed enhanced CO and HCl in the ASMA, which are tracers for boundary layer pollution and tropopause layer (TL) air or stratosp…
Evaluation of the coupled high-resolution atmospheric chemistry model system MECO(n) using in situ and MAX-DOAS NO<sub>2</sub&am…
2021
Abstract. We present high spatial resolution (up to 2.2×2.2 km2) simulations focussed over south-west Germany using the online coupled regional atmospheric chemistry model system MECO(n) (MESSy-fied ECHAM and COSMO models nested n times). Numerical simulation of nitrogen dioxide (NO2) surface volume mixing ratios (VMRs) are compared to in situ measurements from a network with 193 locations including background, traffic-adjacent and industrial stations to investigate the model's performance in simulating the spatial and temporal variability of short-lived chemical species. We show that the use of a high-resolution and up-to-date emission inventory is crucial for reproducing the spatial varia…
The Role of the Local Atomic Order and Boundary Effects on the Electrical Transport of Ceria
2014
Heavily acceptor doped ceria is a material of great relevance for applications in solid oxide fuel cells and oxygen membranes. Depending on the operation temperature, dopant concentration and microstructure (e.g. nanocrystalline vs. microcrystalline), the ionic transport properties of ceria can be mostly hindered by (i) grain boundaries or (ii) local atomic disorder in the bulk. Here, we present a selection of examples (ranging from thin films to ceramics) of how and to which extent these effects can affect the electrical transport properties. Emphasis will be given to the case of heavily doped nanocrystalline and microcrystalline ceria doped with samarium, erbium and ytterbium (dopant conc…