Search results for "SIMULATION"

Improving checkpointing intervals by considering individual job failure probabilities

2021

Checkpointing is a popular resilience method in HPC and its efficiency highly depends on the choice of the checkpoint interval. Standard analytical approaches optimize intervals for big, long-running jobs that fail with high probability, while they are unable to minimize checkpointing overheads for jobs with a low or medium probability of failing. Nevertheless, our analysis of batch traces of four HPC systems shows that these jobs are extremely common.We therefore propose an iterative checkpointing algorithm to compute efficient intervals for jobs with a medium risk of failure. The method also supports big and long-running jobs by converging to the results of various traditional methods for…

RELAXATION OF ELECTRON SPIN DURING FIELD TRANSPORT IN GaAs BULKS

2011

The spin depolarization of drifting electrons in a n-type doped GaAs bulk semiconductor is studied, in a wide range of lattice temperature (40 K < TL < 300 K) and doping density (10^{13} cm^{−3} < n < 10^{16} cm^{−3}), by adopting a semiclassical Monte Carlo approach. The effect of the mechanism of Dyakonov-Perel (DP) on the spin depolarization of the conduction electrons is analyzed as a function of the amplitude of a static electric field, ranging between 0.1 and 6 kV cm^{−1}, by considering the spin dynamics of electrons in both the Γ-valley and the upper L-valleys of the semiconductor. Moreover, the role of the electron-electron scattering mechanism in the suppression of DP spin relaxat…

An exploratory case study of interactive simulation for teaching Ecology

2016

This paper explores the effectiveness of interactive simulation for teaching a selected complex subject, Ecology, in higher education. Specifically, we carry out a lab intervention using interactive agent based simulation, to teach the complex concept of spatially-explicit predator prey interaction to undergraduate students of an advanced module: BIOU9CE (Community Ecology & Conservation Applications) at the University of Stirling. We propose use of Netlogo, an interactive agent-based simulation tool, and evaluate its effectiveness for learning and teaching of interactive simulation developed specifically for the classroom, compared with an existing, less interactive, simulation tool (R).

Large eddy simulations on the effect of the irregular roughness shape on turbulent channel flows

2019

Abstract Large Eddy Simulations (LES) are carried out to investigate on the mean flow in turbulent channel flows over irregular rough surfaces. Here the attention is focused to selectively investigate on the effect induced by crests or cavities of the roughness. The irregular shape is generated through the super-imposition of sinusoidal functions having random amplitude and four different wave-lengths. The irregular roughness profile is reproduced along the spanwise direction in order to obtain a 2D rough shape. The analysis of the mean velocity profiles shows that roughness crests induce higher effect in the outer-region whereas roughness cavities cause the highest effects in the inner-reg…

Forward acceleration of the centre of mass during ski skating calculated from force and motion capture data

2016

The purpose of this paper was to present and evaluate a methodology to determine the contribution of bilateral leg and pole thrusts to forward acceleration of the centre of mass (COM) of cross-country skiers from multi-dimensional ground reaction forces and motion capture data. Nine highly skilled cross-country (XC) skiers performed leg skating and V2-alternate skating (V2A) under constant environmental conditions on snow, while ground reaction forces measured from ski bindings and poles and 3D motion with high-speed cameras were captured. COM acceleration determined from 3D motion analyses served as a reference and was compared to the results of the proposed methodology. The obtained value…

Comparative analysis of two paradigm bacteriophytochromes reveals opposite functionalities in two-component signaling

2021

Bacterial phytochrome photoreceptors usually belong to two-component signaling systems which transmit environmental stimuli to a response regulator through a histidine kinase domain. Phytochromes switch between red light-absorbing and far-red light-absorbing states. Despite exhibiting extensive structural responses during this transition, the model bacteriophytochrome from Deinococcus radiodurans (DrBphP) lacks detectable kinase activity. Here, we resolve this long-standing conundrum by comparatively analyzing the interactions and output activities of DrBphP and a bacteriophytochrome from Agrobacterium fabrum (Agp1). Whereas Agp1 acts as a conventional histidine kinase, we identify DrBphP a…

Il miglioramento energetico nel recupero degli edifici storici. Applicazione al patrimonio architettonico palermitano

L'architettura storica può assumere un ruolo rilevante nel raggiungimento degli obiettivi europei di efficienza energetica per il settore edile, obiettivi che, tuttavia, devono essere compatibili con la conservazione del patrimonio storico e del suo valore culturale. A tal fine è necessario far riferimento ai caratteri specifici dell'architettura storica e alla sua dimensione locale. La presente tesi, sulla base di tale assunto, esamina le prestazioni energetiche degli edifici storici e il loro potenziale miglioramento, concentrandosi sul patrimonio architettonico di Palermo, caso di studio significativo per l'area mediterranea. La ricerca, condotta con riferimento sia alla scala urbana sia…

ATLAS tile calorimeter data quality assessment with commissioning data

2008

TileCal is the barrel hadronic calorimeter of the ATLAS experiment presently in an advanced state of installation and commissioning at the LHC accelerator. The complexity of the experiment, the number of electronics channels and the high rate of acquired events requires a detailed commissioning of the detector, during the installation phase of the experiment and in the early life of ATLAS, to verify the correct behaviour of the hardware and software systems. This is done through the acquisition, monitoring, reconstruction and validation of calibration signals as well as processing data obtained with cosmic ray muons. To assess the detector status and verify its performance a set of tools ha…

Analysis of a Station Black-Out transient in SMR by using the TRACE and RELAP5 code

2014

The present paper deals with the investigation of the evolution and consequences of a Station Black-Out (SBO) initiating event transient in the SPES3 facility [1]. This facility is an integral simulator of a small modular reactor being built at the SIET laboratories, in the framework of the R&D program on nuclear fission funded by the Italian Ministry of Economic Development and led by ENEA. The SBO transient will be simulated by using the RELAP5 and TRACE nodalizations of the SPES3 facility. Moreover, the analysis will contribute to study the differences on the code predictions considering the different modelling approach with one and/or three-dimensional components and to compare the capa…

RELAP5-3D thermal hydraulic analysis of the target cooling system in the SPES experimental facility

2014

The SPES (Selective Production of Exotic Species) experimental facility, under construction at the Italian National Institute of Nuclear Physics (INFN) Laboratories of Legnaro, Italy, is a second generation Isotope Separation On Line (ISOL) plant for advanced nuclear physic studies. The UCx target-ion source system works at temperature of about 2273 K, producing a high level of radiation (10^5 Sv/h), for this reason a careful risk analysis for the target chamber is among the major safety issues. In this paper, the obtained results of thermofluid-dynamics simulations of accidental transients in the SPES target cooling system are reported. The analysis, performed by using the RELAP5-3D 2.4.2 …