Search results for "Simulation."
showing 10 items of 4779 documents
Introducing exergy analysis in life cycle assessment: A case study
2018
Life Cycle Assessment (LCA) is a methodology for assessing the potential environmental aspects associated with a product or service along its life cycle. However, in the case of energy technologies, it is suggested that the LCA of a product encompasses also further aspects other than environmental aspects and primary energy calculations. In particular, to optimize the reduction of raw materials during the whole life cycle, it is important to introduce the assessment of the irreversibility, applying the exergy analysis. In this paper, an integrated approach of exergy analysis and LCA is proposed, developing the Life-cycle quality index able to suggest potential exergy inefficiencies and the …
Determination of transport and kinetic properties in self-propagating high-temperature synthesis
2007
International audience; Exothermic reactions in solid powders are analyzed using the usual macroscopic modeling based on the heat transfer equation coupled to an Arrhenius type of dynamics. This problem have important applications in the synthesis of intermetallics and ceramic materials which occur when a high temperature reaction wave propagates throughout the system. Understanding the mechanism of such processes are thus crucial in mastering real laboratory experiments. We first analyze the model, both theoretically and numerically, for a set of representative parameters. We then use traditional data analyses procedures to estimate from the temperature profiles the same set of representat…
On numerical simulation of electromagnetic field effects in the combustion process
2018
This paper deals with a simplified model taking into account the interplay of compressible, laminar, axisymmetric flow and the electrodynamical effects due to Lorentz force’s action on the combustion process in a cylindrical pipe. The combustion process with Arrhenius kinetics is modelled by a single step exothermic chemical reaction of fuel and oxidant. We analyze non-stationary PDEs with 6 unknown functions: the 3 components of velocity, density, concentration of fuel and temperature. For pressure the ideal gas law is used. For the inviscid flow approximation ADI method is used. Some numerical results are presented.
Evaluation of crack-closure by second harmonic thermoelastic stress analysis
2022
The work illustrates a new experimental approach to evaluate crack-closure in samples undergoing Fatigue Crack-Growing. Crack-closure leaves a peculiar signature on both amplitude and phase of the harmonic of the temperature signal at twice the loading frequency (Second Harmonic), due to the periodic nature of the internal elastic compression stresses. Thermoelastic Stress Analysis (TSA) is successfully applied to reveal such signatures on Single-Edge-Notched steel samples. A methodology is also proposed to evaluate the Crack-Opening-Load from temperature data. The work finally explores the influence of crack-closure on crack-tip identification and on the evaluation of the Stress Intensity …
Consecuencias del manejo integrado de malas hierbas sobre la organización del trabajo y la rentabilidad económica de la explotación agrícola
2008
International audience; Este trabajo tiene por objeto analizar la viabilidad de los sistemas de protección integrada de malas hierbas desde el punto de vista de la organización del trabajo y de la rentabilidad económica. Para ello se comparan cuatro sistemas de protección integrada que reducen o suprimen el aporte de herbicidas, con un sistema convencional. La metodología combina el uso de un programa de simulación con los resultados reales obtenidos en ensayos localizados en una finca experimental del INRA en Dijon (Francia) durante el periodo de 2000 a 2006. Así, se estiman los problemas de organización de trabajo y el margen neto de las explotaciones utilizando los datos reales del exper…
Enabling Backoff for SCM Wake-Up Radio: Protocol and Modeling
2017
In sub-carrier modulation (SCM) wake-up radio (WuR) enabled wireless sensor networks, a node can initiate data transmission at any instant of time. In this letter, we propose to activate a backoff procedure before sending wake-up calls (WuCs) in order to avoid potential collisions among WuCs. Consequently, no backoff is needed for the main radio after a WuC is received. A discrete-time Markov chain model is developed to evaluate the performance. Numerical results on network throughput, energy efficiency, average delay, and collision probability reveal the benefits of enabling backoff for SCM-WuRs, especially under heavy traffic loads or saturated traffic conditions.
Inclusion ratio based estimator for the mean length of the boolean line segment model with an application to nanocrystalline cellulose
2014
A novel estimator for estimating the mean length of fibres is proposed for censored data observed in square shaped windows. Instead of observing the fibre lengths, we observe the ratio between the intensity estimates of minus-sampling and plus-sampling. It is well-known that both intensity estimators are biased. In the current work, we derive the ratio of these biases as a function of the mean length assuming a Boolean line segment model with exponentially distributed lengths and uniformly distributed directions. Having the observed ratio of the intensity estimators, the inverse of the derived function is suggested as a new estimator for the mean length. For this estimator, an approximation…
David Malcolm Raup (1933-2015) at the starting point of a new paradigm for Palaeontology
2020
This is a tribute to the late David Malcolm Raup, one of the major palaeontologists of the second half of the 20 th century. In addition, it is a critical review of his outstanding contributions, mainly in the field of theoretical palaeontology: quantitative modelling, the introduction of probabilistic methods in palaeontology, as well as his great imagination to use techniques from other fields, such as insurance actuary. After a general outline of his youth, I present a general depiction of the main topics of his research as a palaeobiologist: morphology, the structure of the fossil record, evolution, and extinction. He covered areas ranging from the theoretical morphology of coiled shell…
A paradigm of extreme rainfall pluvial floods in complex urban areas: the flood event of 15 July 2020 in Palermo (Italy)
2021
Abstract. In the last years, some regions of the Mediterranean area are witnessing a progressive increase in extreme events, such as urban and flash floods, as a response to the increasingly frequent and severe extreme rainfall events and their ground effects, which are often exacerbated by ever-growing urbanization. In such a context, the traditional defense of urban areas, which are usually based on urban drainage systems designed without regard to the impacts of urbanization and climate change on natural systems, may not be sufficient to deal with the risk deriving from the occurrence of such events. This study focuses on a very recent and particularly intense urban flood that occurred i…
Probing the physics of the solar atmosphere with the Multi-slit Solar Explorer (MUSE): I. Coronal Heating
2022
The Multi-slit Solar Explorer (MUSE) is a proposed NASA MIDEX mission, currently in Phase A, composed of a multi-slit EUV spectrograph (in three narrow spectral bands centered around 171A, 284A, and 108A) and an EUV context imager (in two narrow passbands around 195A and 304A). MUSE will provide unprecedented spectral and imaging diagnostics of the solar corona at high spatial (<0.5 arcsec), and temporal resolution (down to ~0.5s) thanks to its innovative multi-slit design. By obtaining spectra in 4 bright EUV lines (Fe IX 171A , Fe XV 284A, Fe XIX-Fe XXI 108A) covering a wide range of transition region and coronal temperatures along 37 slits simultaneously, MUSE will for the first time …