462 research outputs found
Un alimentatore solare per stazioni remote
Un alimentatore solare può essere un oggetto sofisticato: quello che è stato realizzato dallâLNTS
(Laboratori Nuove Tecologie Strumenti, UF Laboratori, Roma1) è una tessera del progetto STRADIUM
(ASI), e fa tesoro dellâesperienza acquisita nella progettazione degli alimentatori del progetto PEGASO
[Iarocci et al., 2008]. Nato per lâuso in stratosfera, lâalimentatore si presta benissimo allâuso in stazioni
geofisiche remote.
Lâalimentatore accetta tre pannelli solari in ingresso ed utilizza due batterie di elementi Sn-Pb tenendo
conto della variazione delle caratteristiche di carica con la temperatura. Lâintervallo di temperatura di
funzionamento, batterie comprese, va da â50 a + 60°C. La pressione di esercizio va da 1 bar a 5 mbar (dal
livello del mare a 35 Km). Questi valori sono stati verificati sul prototipo, batterie comprese, in camera
termovuoto. Le pagine che seguono sono quelle del manuale scritto a corredo dellâapparecchio: forniscono
una descrizione fedele del principio di funzionamento e del dettaglio tecnico. Le seguenti figure fuori testo
illustrano alcune delle fasi di costruzione e verifica del prototipo
COMPORTAMENTO AD ALTA PRESSIONE DI TRASDUTTORI PIEZOELETTRICI PER APPLICAZIONI DI GEOFISICA SPERIMENTALE
Lâinvestigazione del comportamento acustico di campioni di roccia implica lâuso di trasduttori
piezoelettrici [Spinelli et al., 2009], sia in uso attivo (eccitazione e rilevazione) che passivo (rilevazione delle
onde elastiche generate da fenomeni di fratturazione).
In alcuni casi vengono imposte elevate pressioni per simulare le condizioni di sconfinamento del
campione di roccia in profonditĂ , utilizzando un liquido o un gas. La natura dei trasduttori piezoelettrici
suggerisce che essi non debbano soffrire molto in ambienti in cui la variazioni di pressione o la pressione di
esercizio sia un elemento non trascurabile e possono essere utilizzati in tali condizioni senza particolari
precauzioni con evidenti vantaggi nella semplificazione del set-up sperimentale.
Questa nota è la descrizione delle misure condotte per caratterizzare dei trasduttori piezoelettrici,
nellâintervallo di pressione di interesse (0 - 1000 atm), da utilizzare per scopi sperimentali nellâambito del
progetto europeo ERC Starting Grant Project GLASS InteGrated Laboratories to investigate the mechanics
of ASeismic vs. Seismic faulting.
Per fare ciò due trasduttori sono stati incollati direttamente tra loro in modo da realizzare un
quadripolo, con una porta dâingresso e una di uscita, e ne è stata rilevata la caratteristica ingresso â uscita al
variare della frequenza. Per il rilevamento delle caratteristiche elettriche sono stati usati differenti strumenti
di misura: un generatore di segnali, un oscilloscopio e un analizzatore di reti vettoriale.
Per imporre sui campioni una pressione controllata è stato allestito un apparato meccanico dedicato,
formato da un insieme pistone-cilindro allâinterno del quale viene alloggiata la coppia di trasduttori incollati.
Nel cilindro viene inserito olio (adeguatamente incomprimibile ed elettricamente isolante) come vettore di
pressione; la spinta sul pistone viene esercitata attraverso una pressa idraulica. Una particolare cura è stata
posta nella costruzione del passacavo a tenuta per alte pressioni.
Nei paragrafi che seguono verranno dapprima descritti i trasduttori usati per gli esperimenti e
lâapparato meccanico, quindi si passerĂ alla presentazione delle misure effettuate in varie condizioni e con i
vari strumenti
Un generatore di impulso ad alta tensione per l'eccitazione di trasduttori piezoelettrici: un metodo per studiare la propagazione delle onde elastiche su campioni di rocce
Il dispositivo qui presentato è stato realizzato per lo studio della propagazione di onde elastiche in campioni di roccia [Wood A. W. Et al. 1955]. Mediante tale tecnica si riescono a determinare alcune caratteristiche fisiche delle rocce. Si tratta di un generatore di impulsi ad alta tensione, necessario per lâeccitazione di trasduttori piezoelettrici. La durata dellâimpulso generato è di 1 s, lâampiezza dellâordine del kVolt. Il metodo utilizzato per effettuare la misura consiste nellâeccitare il trasduttore in trasmissione con un singolo impulso e quindi misurarne il tempo di volo con il trasduttore di ricezione. Il lavoro, oltre alla descrizione dello strumento, mostra alcuni esperimenti condotti su campioni di alluminio e diversi tipi di roccia. Tali esperimenti si sono resi necessari sia per il collaudo dello strumento che per la messa a punto del metodo
Study of the time and space distribution of beta+ emitters from 80 MeV/u carbon ion beam irradiation on PMMA
Proton and carbon ion therapy is an emerging technique used for the treatment
of solid cancers. The monitoring of the dose delivered during such treatments
and the on-line knowledge of the Bragg peak position is still a matter of
research. A possible technique exploits the collinear 511\ \kilo\electronvolt
photons produced by positrons annihilation from emitters created by
the beam. This paper reports rate measurements of the 511\ \kilo\electronvolt
photons emitted after the interactions of a 80\ \mega\electronvolt / u fully
stripped carbon ion beam at the Laboratori Nazionali del Sud (LNS) of INFN,
with a Poly-methyl methacrylate target. The time evolution of the
rate was parametrized and the dominance of emitters over the other
species (, , ) was observed, measuring the fraction of
carbon ions activating emitters . The
average depth in the PMMA of the positron annihilation from emitters
was also measured, D_{\beta^+}=5.3\pm1.1\ \milli\meter, to be compared to the
expected Bragg peak depth D_{Bragg}=11.0\pm 0.5\ \milli\meter obtained from
simulations
Charged particle's flux measurement from PMMA irradiated by 80 MeV/u carbon ion beam
Hadrontherapy is an emerging technique in cancer therapy that uses beams of
charged particles. To meet the improved capability of hadrontherapy in matching
the dose release with the cancer position, new dose monitoring techniques need
to be developed and introduced into clinical use. The measurement of the fluxes
of the secondary particles produced by the hadron beam is of fundamental
importance in the design of any dose monitoring device and is eagerly needed to
tune Monte Carlo simulations. We report the measurements done with charged
secondary particles produced from the interaction of a 80 MeV/u fully stripped
carbon ion beam at the INFN Laboratori Nazionali del Sud, Catania, with a
Poly-methyl methacrylate target. Charged secondary particles, produced at
90 with respect to the beam axis, have been tracked with a drift
chamber, while their energy and time of flight has been measured by means of a
LYSO scintillator. Secondary protons have been identified exploiting the energy
and time of flight information, and their emission region has been
reconstructed backtracking from the drift chamber to the target. Moreover a
position scan of the target indicates that the reconstructed emission region
follows the movement of the expected Bragg peak position. Exploting the
reconstruction of the emission region, an accuracy on the Bragg peak
determination in the submillimeter range has been obtained. The measured
differential production rate for protons produced with 83 MeV and emitted at 90 with respect to the beam line is: .Comment: 13 pages, 9 figure
A Psychometric Evaluation of the Multidimensional Social Competence Scale (MSCS) for Young Adults
The current study contributes to previous work on measuring the social phenotype in Autism Spectrum Disorder (ASD) by validating a multidimensional test of social competence developed for use with individuals with and without ASD. The âMultidimensional Social Competence Scaleâ (MSCS) was previously validated as a parent-rating scale with youth 11â18 years with ASD without intellectual disability and typically developing adolescents of comparable age. The current study presents a validation of a self-report version of the MSCS in a non-clinical young adult population (N = 1178, males = 360, females = 817, age range = 17â 25 years). The MSCS consists of seven domains that represent social competence: social motivation, social inferencing, demonstrating empathic concern, social knowledge, verbal conversation skills, nonverbal sending skills, and emotion regulation. These domains are theorized to be indicative of the higher-order construct of social competence. A second higher-order theorization of the MSCS structure posits that 3 of these factors are indicative of social responsiveness, and the remaining 4 factors are indicative of social understanding and emotion regulation. Our findings indicated support for each of the theorized multidimensional factor structures. Reliability, optimal scoring, convergent and discriminant validity of the measure, as well as implications for future research are discussed
The use of 3D printing in the development of gaseous radiation detectors
Fused Deposition Modelling has been used to produce a small, single wire, Iarocci-style drift tube to demonstrate the feasibility of using the Additive Manufacturing technique to produce cheap detectors, quickly. Recent technological developments have extended the scope of Additive Manufacturing, or 3D printing, to the possibility of fabricating Gaseous Radiation Detectors, such as Single Wire Proportional Counters and Time Projection Chambers. 3D printing could allow for the production of customisable, modular detectors; that can be easily created and replaced and the possibility of printing detectors on-site in remote locations and even for outreach within schools.
The 3D printed drift tube was printed using Polylactic acid to produce a gas volume in the shape of an inverted triangular prism; base length of 28 mm, height 24.25 mm and tube length 145 mm. A stainless steel anode wire was placed in the centre of the tube, mid-print. P5 gas (95% Argon, 5% Methane) was used as the drift gas and a circuit was built to capacitively decouple signals from the high voltage. The signal rate and average pulse height of cosmic ray muons were measured over a range of bias voltages to characterise and prove correct operation of the printed detector
A comparison of the development of audiovisual integration in children with autism spectrum disorders and typically developing children
This study aimed to investigate the development of audiovisual integration in children with Autism Spectrum Disorder (ASD). Audiovisual integration was measured using the McGurk effect in children with ASD aged 7â16 years and typically developing children (control group) matched approximately for age, sex, nonverbal ability and verbal ability. Results showed that the children with ASD were delayed in visual accuracy and audiovisual integration compared to the control group. However, in the audiovisual integration measure, children with ASD appeared to âcatch-upâ with their typically developing peers at the older age ranges. The suggestion that children with ASD show a deficit in audiovisual integration which diminishes with age has clinical implications for those assessing and treating these children
PEGASO: Polar Explorer for Geomagnetic And other Scientific Observation
PEGASO (Polar Explorer for Geomagnetic And other Scientific Observation) program has been created to conduct small experiments in as many disciplines on-board of small stratospheric balloons.
PEGASO uses the very low expensive pathfinder balloons. Stratospheric pathfinders are small balloons commonly used to explore the atmospheric circumpolar upper winds and to predict the trajectory for big LDBs (Long Duration Balloons). Installing scientific instruments on pathfinder and using solar energy to power supply the system, we have the opportunity to explorer the Polar Regions, during the polar summer, following circular trajectory. These stratospheric small payload have flown for 14 up to 40 days, measuring the magnetic field of polar region, by means of 3-axis-fluxgate magnetometer.
PEGASO payload uses IRIDIUM satellite telemetry (TM). A ground station communicates with one or more payloads to download scientific and house-keeping data and to send commands for ballast releasing, for system resetting and for operating on the separator system at the flight end.
The PEGASO missions have been performed from the Svalbard islands with the logistic collaboration of the Andoya Rocket Range and from the Antarctic Italian base. Continuous trajectory predictions, elaborated by Institute of Information Science and Technology (ISTI-CNR), were necessary for the flight safety requirements in the north hemisphere. This light payloads (<10 Kg) are realized by the cooperation between the INGV and the Physics department âLa Sapienzaâ University and it has operated five times in polar areas with the sponsorship of Italian Antarctic Program (PNRA), Italian Space Agency (ASI).
This paper summarizes important results about stratospheric missions.PNRA, ASI.Published940-9455IT. Osservazioni satellitariN/A or not JCRope
Global-local visual processing in high functioning children with autism: Structural vs. implicit task biases
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