Search results for "Reso"
showing 10 items of 13841 documents
Resolvent estimates for elliptic quadratic differential operators
2011
Sharp resolvent bounds for non-selfadjoint semiclassical elliptic quadratic differential operators are established, in the interior of the range of the associated quadratic symbol.
Enhancing Metastability by Dissipation and Driving in an Asymmetric Bistable Quantum System.
2018
The stabilizing effect of quantum fluctuations on the escape process and the relaxation dynamics from a quantum metastable state are investigated. Specifically, the quantum dynamics of a multilevel bistable system coupled to a bosonic Ohmic thermal bath in strong dissipation regime is analyzed. The study is performed by a non-perturbative method based on the real-time path integral approach of the Feynman-Vernon influence functional. We consider a strongly asymmetric double well potential with and without a monochromatic external driving, and with an out-of-equilibrium initial condition. In the absence of driving we observe a nonmonotonic behavior of the escape time from the metastable regi…
Errores conceptuales en el estudio del equilibrio químico : nuevas aportaciones relacionadas con la incorrecta aplicación del principio de Le Chateli…
2021
Resumen basado en el de la publicación Resumen en inglés La utilidad limitada del principio de Le Chatelier y su formulación vaga y ambigua pueden ser algunas de las fuentes de conceptos erróneos en el equilibrio químico. Para diagnosticar conceptos erróneos, se administró una prueba escrita a 170 estudiantes universitarios de primer año. Las respuestas revelaron que los errores surgieron en términos generales: a) la mala aplicación y la incomprensión del Principio de Le Chatelier; b) utilización de recordatorios de memorización y procedimientos algorítmicos; c) control incorrecto de las variables involucradas y uso limitado de la ley de equilibrio químico; d) falta de dominio de los princi…
Analysis of MAC-level throughput in LTE systems with link rate adaptation and HARQ protocols
2015
LTE is rapidly gaining momentum for building future 4G cellular systems, and real operational networks are under deployment worldwide. To achieve high throughput performance, in addition to an advanced physical layer design LTE exploits a combination of sophisticated mechanisms at the radio resource management layer. Clearly, this makes difficult to develop analytical tools to accurately assess and optimise the user perceived throughput under realistic channel assumptions. Thus, most existing studies focus only on link-layer throughput or consider individual mechanisms in isolation. The main contribution of this paper is a unified modelling framework of the MAC-level downlink throughput of …
Device-to-device communication for LTE-advanced network system
2014
Device-to-device (D2D) communication has been proposed as a mean for local connections in future ellular networks in order to provide improved throughput, spectrum savings, and longer battery lives. Here we widen the investigations of D2D communication to a 3GPP Long Term Evolution (LTE) system simulated in the interference limited macro-cellular environment, in which D2D communication is applied with D2D specific power control and resource allocation schemes and with a wide range of deployment ratios. Furthermore, we introduce channel model parameters applicable for a fair performance comparison between conventional cellular and D2D enhanced systems. The simulation results demonstrate that…
A GEM-TPC in twin configuration for the Super-FRS tracking of heavy ions at FAIR
2018
The GEM-TPC [1] described herein will be part of the standard beam-diagnostics equipment of the Super-FRS [2] . This chamber will provide tracking information for particle identification at rates up to 1 MHz on an event-by-event basis. The key requirements of operation for these chambers are: close to 100% tracking efficiency under conditions of high counting rate, spatial resolution below 1 mm and a superb large dynamic range covering projectiles from Z=1 up to Z=92. The current prototype consists of two GEM-TPCs inside a single vessel, which are operating independently and have electrical drift fields in opposite directions. The twin configuration is done by flipping one of the GEM-TPCs o…
Radiofrequency and 2.45 GHz electron cyclotron resonance H− volume production ion sources
2016
The volume production of negative hydrogen ions (H-) in plasma ion sources is based on dissociative electron attachment (DEA)to rovibrationally excited hydrogen molecules(H2), which is a two-step process requiring both, hot electrons for ionization, and vibrational excitation of the H2 and cold electrons for the H- formation through DEA. Traditionally H- ion sources relying on the volume production have been tandem-type arc discharge sources equipped with biased filament cathodes sustaining the plasma by thermionic electron emission and with a magnetic filter separating the main discharge from the H- formation volume. The main motivation to develop ion sources based on radiofrequency (RF) o…
DEM-resolution control on rainfall-triggered landslide modeling within a triangulated network-based model
2019
Catchment slope distribution significantly controls rainfall-triggered landslide modeling, in both direct and indirect ways. Slope directly determines the soil volume associated with instability. Indirectly, it affects the subsurface lateral redistribution of soil moisture across the basin, which in turn determines the water pore pressure conditions that impact slope stability. It is thus clear that the accuracy in reproducing slope distribution may be crucial in slope stability analysis. The resolution of the Digital Elevation Model (DEM) regulates the description of the topography. The correlation between raster resolution and landslide model outputs has been investigated in the literatur…
Strongly Coupled Coherent Phonons in Single-Layer MoS 2
2019
We present a transient absorption setup combining broadband detection over the visible-UV range with high temporal resolution ($\sim$20fs) which is ideally suited to trigger and detect vibrational coherences in different classes of materials. We generate and detect coherent phonons (CPs) in single layer (1L) MoS$_2$, as a representative semiconducting 1L-transition metal dichalcogenide (TMD), where the confined dynamical interaction between excitons and phonons is unexplored. The coherent oscillatory motion of the out-of-plane $A'_{1}$ phonons, triggered by the ultrashort laser pulses, dynamically modulates the excitonic resonances on a timescale of few tens fs. We observe an enhancement by…