Nonequilibrium Green's functions in the study of heat transport of driven nanomechanical systems

We review a recent theoretical development based on non-equilibrium Green's function formalism to study heat transport in nanomechanical devices modeled by phononic systems of coupled quantum oscillators driven by ac forces and connected to phononic reservoirs. We present the relevant equations to calculate the heat currents flowing along different regions of the setup, as well as the power developed by the time-dependent forces. We also present different strategies to evaluate the Green's functions exactly or approximately within the weak driving regime. We finally discuss the different mechanisms in which the ac driving forces deliver the energy. We show that, besides generating heat, the forces may operate exchanging energy as a quantum engine.Comment: 14 pages, 2 figure

Transport phenomena in helical edge states interferometers. A Green's function approach

We analyze the current and the shot-noise of an electron interferometer made of the helical edge states of a two-dimensional topological insulator within the framework of non-equilibrium Green's functions formalism. We study in detail setups with a single and with two quantum point contacts inducing scattering between the different edge states. We consider processes preserving the spin as well as the effect of spin-flip scattering. In the case of a single quantum point contact, a simple test based on the shot-noise measurement is proposed to quantify the strength of the spin-flip scattering. In the case of two single point contacts with the additional ingredient of gate voltages applied within a finite-size region at the top and bottom edges of the sample, we identify two type of interference processes in the behavior of the currents and the noise. One of such processes is analogous to that taking place in a Fabry-P\'erot interferometer, while the second one corresponds to a configuration similar to a Mach-Zehnder interferometer. In the helical interferometer these two processes compete.Comment: 15 pages, 13 figure

Nonlinear modelling and control of a common rail injection system for diesel engines

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LightGWAS: A Novel Machine Learning Procedure for Genome-Wide Association Study

This paper proposes a novel machine learning procedure for genome-wide association study (GWAS), named LightGWAS. It is based on the LightGBM framework, in addition to being a single, resilient, autonomous and scalable solution to address common limitations of GWAS implementations found in the literature. These include reliance on massive manual quality control steps and specific GWAS methods for each type of dataset morphology and size. Through this research, LightGWAS has been contrasted against PLINK2, one of the current state-of-the-art for GWAS implementations based on general linear model with support to firth regularisation. The mean differences measured upon standard classification metrics, extracted via quantitative empirical tests through k-fold cross-validation technique, indicated that LightGWAS outperforms PLINK2 for balanced, imbalanced, and high-imbalanced genomic datasets. Paired difference tests denoted statistical significance in the results extracted from the experiments with imbalanced datasets. This article contributes to the body of knowledge by presenting a potentially more efficient GWAS procedure based on nonparametric approaches. LightGWAS ensures adaptability with higher precision in the discovery of causal single-nucleotide polymorphisms, thanks to the leaf-wise tree growth algorithm offered by the state-of-the-art for gradient boosting decision trees. Control for false-positives and statistical power are automatically addressed by the model’s training process, which significative reduces human dependency during the study design

Effective tunneling processes in an interferometer of helical edge states with an antidot

We consider an interferometer of edge states of a two-dimensional topological insulator with an antidot. We analyze the mechanisms leading to an effective tunneling with spin flip between different helical states.Fil: Rizzo, Bruno. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Camjayi, Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Arrachea, Liliana del Carmen. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; Argentin

a novel energy efficiency metric for model based fault diagnosis of telecommunication central offices

Abstract A novel energy metric is presented, to be adopted for monitoring and diagnosis of telecommunication (TLC) central offices (COFs). Such an activity is motivated by the TLC players need to substantially reduce their energy demand, both to increase their market competitiveness and meet the stringent green-house gas (GHG) emission regulations. The proposed metric, the utilization factor (UF), was thus defined according to the energy break-down of TLC-COFs. Then, suitable data-processing techniques were applied to develop a diagnosis-oriented UF model. Model accuracy, found to be always capable of guaranteeing UF estimation errors safely below 15 % for all non-faulty COFs, was proven adequate to perform model-based fault detection and isolation of relevant malfunctioning, such as abnormal data acquisition and non-optimal energy management

Noble gas solubilities in silicate melts: New experimental results and a comprehensive model of the effects of liquid composition, temperature and pressure

International audienceNew experimental data of Ar and Ne solubility at pressures up to 360 MPa in alkali-basaltic (Mt. Etna, Italy) and rhyolitic (Vulcano Island, Italy) melts are presented. Solubility experiments have been conducted in internally heated pressure vessels at 1200 °C under nominally anhydrous conditions. Ar and Ne contents dissolved in the experimental glasses were then measured by quadrupole mass spectrometry. Over the pressure range investigated, Ar and Ne solubilities vary linearly with Ar and Ne pressures and can be described by Henry's constant (kAr,Ne = PAr, Ne / xAr, Ne, where PAr, Ne is the partial pressure of Ar or Ne and xAr, Ne is the molar fraction of Ar or Ne in the melt) of 7.6 ± 0.8 × 105 and 1.9 ± 0.4 × 105 MPa, respectively for Ar and Ne in the basaltic melt and 1.5 ± 0.2 × 105 and 3.8 ± 0.2 × 104 MPa, respectively for Ar and Ne in the rhyolitic melt. In accordance with existing models, rhyolitic melts show higher noble gas solubilities than basaltic melts, Ne solubility being higher than that of Ar in a given composition. We propose a semi-empirical model of noble gas (Ar, Ne and He) solubility calibrated on a very large set of measurements in natural and synthetic silicate melts. The model expands the concept of ionic porosity in terms of porosity accessible for noble gas dissolution in melt, taking into account the large-scale structural effects of cations, as well as temperature and pressure. The model is valid over a wide range of temperatures (800–1600 °C), pressures (up to 3 GPa) and compositions, being useful for both geological and physico-chemical studies

On two Italian Gall Midges (Diptera Cecidomyiidae) and their parasitoids

Some biological data on Cystiphora sonchi (Bremi) and Asphondylia trabuti Marchal in Italy are reported. C. sonchi, previously known only for N Italy, is also recorded for S Italy, Sardinia and Sicily. It induces galls on the leaves of Sonchus spp. (Compositae) all the year around, except for the second half of July and August. The number of galls per leaf was higher in summer (11.6) than in winter (7.4). Overall 5-6 generations per year were observed, with a maximum number of individuals in spring-summer. Larvae often merge in the same gall, pupating inside it and emerging from the lower leaf surface; in winter they can leave galls and pupate outside them. On the whole 426 C. sonchi and 381 parasitoids were reared; 359 were Aprostocetus microscopicus (Rondani) (Hymenoptera Eulophidae) and 22 Synopeas larides (Walker) (Hymenoptera Platygasteridae); the latter has not been previously quoted for Italy. A. trabuti, previously known as phytophagous on fruits of Solanum tuberosum L., is here recorded for the first time in Italy and as phytophagous of S. nigrum L. Larvae live gregariously, developing and pupating inside fruits between May and December. They emerge in about two weeks, their number peaking in spring; at least 5 generations per year were observed. On the whole 100 A. trabuti and 91 parasitoids were reared; 88 were Eurytoma dentata Mayr (Hymenoptera Eurytomidae), previously unrecorded as parasitoids of this gall midge, and 3 were unidentified Pteromalidae. Key words: Cystiphora sonchi, Asphondylia trabuti, Sonchus spp., Solanum nigrum.SU DUE SPECIE ITALIANE DI CECIDOMIDI GALLIGENI E SUI LORO PARASSITOIDI Si riportano alcuni dati biologici su Cystiphora sonchi (Bremi) ed Asphondylia trabuti Marchal (Diptera Cecidomyiidae) in Italia. C. sonchi era nota solo per le regioni settentrionali e viene riportata ora anche per l’Italia meridionale, la Sardegna e la Sicilia; essa induce galle sulle foglie delle specie del gen. Sonchus (Compositae) durante tutto l’anno divenendo rara nel periodo metà luglio-agosto. Il numero di galle estive per foglia (11,6) è risultato più alto di quelle inver- nali (7,4). In totale sono state osservate 5-6 generazioni per anno con un picco numerico in pri- mavera-estate. Le larve spesso confluiscono nella stessa galla e vi si impupano, sfarfallando dalla pagina inferiore; in inverno alcune larve abbandonano le galle e si impupano aldifuori di esse. In totale sono stati allevati 426 C. sonchi e 381 parassitoidi, 359 dei quali sono risultati Aprostocetus microscopicus (Rondani) (Hymenoptera Eulophidae), 22 Synopeas larides (Walker) (Hymenoptera Platygasteridae). Quest’ultima specie viene segnalata per la prima volta in Italia. Asphondylia trabuti, nota già come fitofago dei frutti di Solanum tuberosum, viene riportata per la prima volta in Italia e su Solanum nigrum; le larve sono gregarie, si sviluppano tra maggio e dicembre con un picco in primavera e si impupano all’interno dei frutti, completando il ciclo in circa due settimane. Sono state osservate almeno 5 generazioni per anno. In totale sono stati ottenuti 100 A. trabuti e 91 parassitoidi, 88 dei quali sono risultati Eurytoma dentata Mayr (Hymenoptera Eurytomidae), riportata per la prima volta come suo parassitoide, e 3 Pteromalidae. Parole chiave: Cystiphora sonchi, Asphondylia trabuti, Sonchus spp., Solanum nigrum.