Search results for " Simulation"
showing 10 items of 4034 documents
Northern Hemisphere atmospheric pattern enhancing Eastern Mediterranean Transient-type events during the past 1000 years
2021
High-resolution climate model simulations for the last millennium were used to elucidate the main winter Northern Hemisphere atmospheric pattern during enhanced Eastern Mediterranean Transient (EMT-type) events, a situation in which an additional overturning cell is detected in the Mediterranean at the Aegean Sea. The differential upward heat flux between the Aegean Basin and the Gulf of Lion was taken as a proxy of EMT-type events and correlated with winter mean geopotential height at 500 mbar in the Northern Hemisphere (20–90∘ N and 100∘ W–80∘ E). Correlations revealed a pattern similar to the East Atlantic/Western Russian (EA/WR) mode as the main driver of EMT-type events, with the past …
RAMS-forecasts comparison of typical summer atmospheric conditions over the Western Mediterranean coast
2014
Abstract The Regional Atmospheric Modeling System (RAMS) has been used in order to perform a high-resolution numerical simulation of two meteorological events related to the most common atmospheric environments during the summer over the Western Mediterranean coast: mesoscale circulations and western synoptic advections. In this regard, we take advantage of the operational RAMS configuration running within the real-time forecasting system environment already implemented over this Mediterranean area, precisely in the Valencia Region and nearby areas. The attention of this paper is especially focused on identifying the main features of both events and the ability of the model in resolving the…
Rainfall simulation and Structure-from-Motion photogrammetry for the analysis of soil water erosion in Mediterranean vineyards
2016
[EN] Soil water erosion is a serious problem, especially in agricultural lands.Among these, vineyards deserve attention, because they constitute for the Mediterranean areas a type of land use affected by high soil losses. A significant problem related to the study of soil water erosion in these areas consists in the lack of a standardized procedure of collecting data and reporting results, mainly due to a variability among the measurement methods applied. Given this issue and the seriousness of soil water erosion in Mediterranean vineyards, this works aims to quantify the soil losses caused by simulated rainstorms, and compare them with each other depending on two different methodologies: (…
EXACT SOLUTIONS FOR A CLASS OF FRACTAL TIME RANDOM WALKS
1995
Fractal time random walks with generalized Mittag-Leffler functions as waiting time densities are studied. This class of fractal time processes is characterized by a dynamical critical exponent 0<ω≤1, and is equivalently described by a fractional master equation with time derivative of noninteger order ω. Exact Greens functions corresponding to fractional diffusion are obtained using Mellin transform techniques. The Greens functions are expressible in terms of general H-functions. For ω<1 they are singular at the origin and exhibit a stretched Gaussian form at infinity. Changing the order ω interpolates smoothly between ordinary diffusion ω=1 and completely localized behavior in the …
Simulating music with associative self-organizing maps
2018
Abstract We present an architecture able to recognise pitches and to internally simulate likely continuations of partially heard melodies. Our architecture consists of a novel version of the Associative Self-Organizing Map (A-SOM) with generalized ancillary connections. We tested the performance of our architecture with melodies from a publicly available database containing 370 Bach chorale melodies. The results showed that the architecture could learn to represent and perfectly simulate the remaining 20% of three different interrupted melodies when using a context length of 8 centres of activity in the A-SOM. These promising and encouraging results show that our architecture offers somethi…
The superlattice model of lateral organization of membranes and its implications on membrane lipid homeostasis.
2008
AbstractMost biological membranes are extremely complex structures consisting of hundreds of different lipid and protein molecules. According to the famous fluid-mosaic model lipids and many proteins are free to diffuse very rapidly in the plane of the membrane. While such fast diffusion implies that different membrane lipids would be laterally randomly distributed, accumulating evidence indicates that in model and natural membranes the lipid components tend to adopt regular (superlattice-like) distributions. The superlattice model, put forward based on such evidence, is intriguing because it predicts that 1) there is a limited number of allowed compositions representing local minima in mem…
Model calculations of ion transport against its concentration gradient when the driving force is a pH difference across a charged membrane
1997
Model calculations of the steady-state ion transport against its external concentration gradient when the driving force of this transport is a pH difference across a charged membrane are presented. We have solved numerically the exact Nernst-Planck equations without any additional simplifying approximation, such as the Goldman constant field assumption within the membrane. The validity of this assumption for a broad range of pH values, and salt and membrane fixed charge concentrations was analyzed critically. The membrane characteristics studied are the ionic fluxes and the membrane potential. Special attention is paid to the physical mechanism which leads to the ion transport against the c…
Lipid carbonyl groups terminate the hydrogen bond network of membrane-bound water.
2015
We present a combined experimental sum-frequency generation (SFG) spectroscopy and ab initio molecular dynamics simulations study to clarify the structure and orientation of water at zwitterionic phosphatidylcholine (PC) lipid and amine N-oxide (AO) surfactant monolayers. Simulated O-H stretch SFG spectra of water show good agreement with the experimental data. The SFG response at the PC interface exhibits positive peaks, whereas both negative and positive bands are present for the similar zwitterionic AO interface. The positive peaks at the water/PC interface are attributed to water interacting with the lipid carbonyl groups, which act as efficient hydrogen bond acceptors. This allows the …
Boundary discretization based on the residual energy using the SGBEM
2007
Abstract The paper has as objective the estimation of the error in the structural analysis performed by using the displacement approach of the Symmetric Galerkin Boundary Element Method (SGBEM) and suggests a strategy able to reduce this error through an appropriate change of the boundary discretization. The body, characterized by a domain Ω and a boundary Γ−, is embedded inside a complementary unlimited domain Ω∞⧹Ω bounded by a boundary Γ+. In such new condition it is possible to perform a separate valuation of the strain energies in the two subdomains through the computation of the work, defined generalized, obtained as the product among nodal and weighted quantities on the actual boundar…
Mechanical Bistable Structures for Microrobotics and Mesorobotics from Microfabrication to Additive Manufacturing
2018
International audience; The use of mechanical bistable structures in the design of microrobots and mesorobots has many advantages especially for flexible robotic structures. However, depending on the fabrication technology used, the adequacy of theoretical and experimental mechanical behaviors can vary widely. In this paper, we present the manufacturing results of bistable structures made with two extensively used contemporary technologies: MEMS and FDM additive manufacturing. Key issues of these fabrication technologies are discussed in the context of microrobotics and mesorobotics applications.