A novel topology for a HEMT negative current mirror

A new solution for the implementation of a HEMT negative current source is presented. The topology can be also profitably employed as a current mirror and as an active load in high-gain MMICs voltage amplifiers. A small-signal model of the proposed circuit is developed which allows to find accurate expressions for the required transfer functions (i.e., the output impedance of the current source, and the current gain of the circuit when operated as a current mirror). Design examples using Philips PML ED02AH GaAs PHEMT process are provided. Spice simulations show that a 10- kW output impedance for the current source and a 35dB voltage gain for a differential pair loaded with the proposed current mirror are easily achieved

Obstructive sleep apnea syndrome in the pediatric age: the role of the dentist

Sleep disordered breathing in children designates a wide spectrum of respiratory disorders characterized by partial or complete obstruction of the upper airways. It ranges from primary snoring, its mildest clinical manifestation, to obstructive sleep apnea syndrome (OSAS): complete obstruction of the upper airways with cessation of airflow. The aim of this paper is to highlight the roles of the pediatric dentist and the orthodontist in the therapeutic approach to pediatric OSAS as a "sentinel" who can detect early signs of the disease for immediate referral to the otolaryngologist and as an active participant in therapy

Method of comparison equations for cosmological perturbations

We apply the method of comparison equations to study cosmological perturbations during inflation, obtaining the full power spectra of scalar and tensor perturbations to first and to second order in the slow-roll parameters. We compare our results with those derived by means of other methods, in particular the Green's function method and the improved WKB approximation, and find agreement for the slow-roll structure. The method of comparison equations, just as the improved WKB approximation, can however be applied to more general situations where the slow-roll approximation fails.Comment: 20 pages, 10 figure

Constraining the evolution of the CMB temperature with SZ measurements from Planck data

The CMB temperature-redshift relation, T_CMB(z)=T_0(1+z), is a key prediction of the standard cosmology, but is violated in many non standard models. Constraining possible deviations to this law is an effective way to test the LambdaCDM paradigm and to search for hints of new physics. We have determined T_CMB(z), with a precision up to 3%, for a subsample (104 clusters) of the Planck SZ cluster catalog, at redshift in the range 0.01-- 0.94, using measurements of the spectrum of the Sunyaev Zel'dovich effect obtained from Planck temperature maps at frequencies from 70 to 353 GHz. The method adopted to provide individual determinations of T_CMB(z) at cluster redshift relies on the use of SZ intensity change, Delta I_SZ(nu), at different frequencies, and on a Monte-Carlo Markov Chain approach. By applying this method to the sample of 104 clusters, we limit possible deviations of the form T_CMB(z)=T_0(1+z)^(1-beta) to be beta= 0.022 +/- 0.018, at 1 sigma uncertainty, consistent with the prediction of the standard model. Combining these measurements with previously published results we get beta=0.016+/-0.012.Comment: submitted to JCAP, 21 pages, 8 figure

Synthesis of the presentation of INSPYRE results to the User Group

INSPYRE created a user group composed of key customers for the project’s results, which included representatives of the designers of the ESNII reactor concepts (ASTRID, MYRRHA, ALFRED, ALLEGRO), as well as of fuel manufacturers and utilities (ORANO, EDF). A first meeting had been organized in August 2018 to present the INSPYRE approach and activities to the users and discuss their needs in the area covered by INSPYRE activities. The synthesis of the meeting is reported in INSPYRE Deliverable D9.4. Three meetings with the user group were then organised throughout the project to present the approach and results of the project to the Users, get their feedback on these results and discuss follow-up activities. - The Second User Group meeting took place on January 17th, 2020 and was dedicated to the developments made in the fuel performance codes considered in the project and their assessment against the selected fast reactor irradiation experiments - The third User Group meeting was held on May 31st, 2021 and was dedicated to the simulation of the fuel elements in normal operating conditions of the ASTRID reactor concept - The final User Group meeting was organised jointly with the second Scientific Advisory Committee meeting on May 24th, 2022 and concerned the overall scientific outcomes of INSPYRE. The present deliverable reports the presentations made during the meetings and the synthesis of the exchanges that followed

Information, formation and training for the maintenance operations: the lesson learned from fatal accidents

The list of possible machinery / equipment-related injuries is as long as it is worrying; they represent a non-negligible part of the total accidents in most industrial sectors, in terms of both numbers and severity, in normal conditions and during the maintenance operations. Lack of maintenance or inadequate maintenance can lead to dangerous situations, accidents and health problems; but, at the same time, maintenance itself is a high-risk activity due to special hazards resulting from the particular nature of the work. Moreover, the workers involved are more likely than other employees directly exposed to the risks, since direct contact between the worker and the machinery to be maintained cannot be substantially reduced

Triple Experiment Spectrum of the Sunyaev-Zeldovich Effect in the Coma Cluster: H_0

The Sunyaev-Zeldovich (SZ) effect was previously measured in the Coma cluster by the Owens Valley Radio Observatory and Millimeter and IR Testa Grigia Observatory experiments and recently also with the Wilkinson Microwave Anisotropy Probe satellite. We assess the consistency of these results and their implications on the feasibility of high-frequency SZ work with ground-based telescopes. The unique data set from the combined measurements at six frequency bands is jointly analyzed, resulting in a best-fit value for the Thomson optical depth at the cluster center, tau_{0}=(5.35 \pm 0.67) 10^{-3}. The combined X-ray and SZ determined properties of the gas are used to determine the Hubble constant. For isothermal gas with a \beta density profile we derive H_0 = 84 \pm 26 km/(s\cdot Mpc); the (1\sigma) error includes only observational SZ and X-ray uncertainties.Comment: 11 pages, 1 figur

Application of the SCIANTIX fission gas behaviour module to the integral pin performance in sodium fast reactor irradiation conditions

The sodium-cooled fast reactor is among the innovative nuclear technologies selected in the framework of the development of Generation IV concepts, allowing the irradiation of uranium-plutonium mixed oxide fuels (MOX). A fundamental step for the safety assessment of MOX-fuelled pins for fast reactor applications is the evaluation, by means of fuel performance codes, of the integral thermal-mechanical behaviour under irradiation, involving the fission gas behaviour and release in the fuel-cladding gap. This work is dedicated to the performance analysis of an inner-core fuel pin representative of the ASTRID sodium-cooled concept design, selected as case study for the benchmark between the GERMINAL and TRANSURANUS fuel performance codes. The focus is on fission gas-related mechanisms and integral outcomes as predicted by means of the SCIANTIX module (allowing the physics-based treatment of inert gas behaviour and release) coupled to both fuel performance codes. The benchmark activity involves the application of both GERMINAL and TRANSURANUS in their “pre-INSPYRE” versions, i.e., adopting the state-of-the-art recommended correlations available in the codes, compared with the “post-INSPYRE” code results, obtained by implementing novel models for MOX fuel properties and phenomena (SCIANTIX included) developed in the framework of the INSPYRE H2020 Project. The SCIANTIX modelling includes the consideration of burst releases of the fission gas stored at the grain boundaries occurring during power transients of shutdown and start-up, whose effect on a fast reactor fuel concept is analysed. A clear need to further extend and validate the SCIANTIX module for application to fast reactor MOX emerges from this work; nevertheless, the GERMINAL-TRANSURANUS benchmark on the ASTRID case study highlights the achieved code capabilities for fast reactor conditions and paves the way towards the proper application of fuel performance codes to safety evaluations on Generation IV reactor concepts

Synthesis of INSPYRE results

This document presents a synthesis of the results of the INSPYRE H2020 European Project, which was dedicated to the investigation and simulation of uranium-plutonium mixed oxide (MOX) fuels for fast reactors and their behaviour under irradiation. It first describes the progress in the understanding and description of the behaviour of MOX fuels obtained thanks to the combination of basic research (multiscale modelling and separate effect experiments) and examination of fuels irradiated in reactors in past experiments. Four operational issues were particularly studied: margin to fuel melting; irradiated fuel thermochemistry and interaction with the cladding; self-diffusion properties and inert gas behaviour; evolution of mechanical properties under irradiation. Second, the advances made in the simulation of fast reactor MOX fuels thanks to the development of more physically justified models and their implementations in three European fuel performance codes are presented. Then, the results of the simulation of two ESNII reactor cores are shown: normal operation conditions in the ASTRID sodium fast reactor prototype and normal and transient conditions in the lead-bismuth cooled reactor of the MYRRHA accelerator driven system. Finally, the activities conducted concerning education and training, dissemination, exploitation and communication are summarized