1,162 research outputs found
Technical and software upgrades completed and planned at OARPAF
No full textWe present technical, instrumental, and software upgrades completed and
planned at astronomical observatory called "Osservatorio Astronomico Regionale
Parco Antola, Fascia" (OARPAF), hosting an 80cm, alt-az Cassegrain-Nasmyth
telescope. The observatory, located in the Ligurian Apennines, can currently be
operated either for scientific (photometry camera) or amateur (ocular)
observations, by switching the tertiary mirror between the two Nasmyth foci
using a manual handle. The main scientific observational topics are related up
to now to exoplanetary transits, QSOs, and gravitationally lensed quasars, and
results are being recently published. A remotization and robotization strategy
of the entire structure (telescope, dome, instruments, sensors and monitoring)
have been set up and it is in progress. We report the current upgrades, mainly
related for what concerns the "hardware" side to the robotization of the dome.
On the instrumentation side, a new modular support for instruments with
spectrophotometric capabilities is on a preliminary design phase, improving the
telescope performances and broadening the potential science fields. In this
framework, the procurement of spectrophotometric material has started. On the
software side, an innovative web-based software relying on websockets and
node.js can already be used to control the camera, and it will be extended to
manage the other components of the instrument, of the observatory, and of the
image database storage
Characterization for high dynamic range imaging
No full textIn this paper we present a new practical camera characterization technique to improve color accuracy in high dynamic range (HDR) imaging. Camera characterization refers to the process of mapping device-dependent signals, such as digital camera RAW images, into a well-defined color space. This is a well-understood process for low dynamic range (LDR) imaging and is part of most digital cameras — usually mapping from the raw camera signal to the sRGB or Adobe RGB color space. This paper presents an efficient and accurate characterization method for high dynamic range imaging that extends previous methods originally designed for LDR imaging. We demonstrate that our characterization method is very accurate even in unknown illumination conditions, effectively turning a digital camera into a measurement device that measures physically accurate radiance values — both in terms of luminance and color — rivaling more expensive measurement instruments
Analysis of object tracking algorithms performance on event-based datasets
No full textThe event-based camera represents a revolutionary concept, having an asynchronous output. The pixels of dynamic vision sensors react to the brightness change, resulting in streams of events at very small intervals of time. This paper provides a model to track objects in neuromorphic datasets, using clustering. In addition, a non-linear filter is applied to correct the estimation of the object position. Both single and multi-object tracking algorithms are provided and their performance is analyzed using different metrics, including the clustering evaluation scores and the tracking accuracy. The accuracy is over 0.6 for multi-target tracking and more than 0.7 for single object tracking. Besides the proposed model, a comparison between different possible approaches for event-based data tracking is provided.https://github.com/aolaru11/Object-tracking-using-event-based-camera The implementation of the object tracking model using event based cameraCSE3000 Research ProjectComputer Science and Engineerin
“The DRAGO gamma camera"
No full textIn this work, we present the results of the experimental characterization of the DRAGO (DRift detector Array-based Gamma camera for Oncology), a detection system developed for high-spatial resolution gamma-ray imaging. This camera is based on a monolithic array of 77 silicon drift detectors (SDDs), with a total active area of 6.7 cm(2), coupled to a single 5-mm-thick CsI(Tl) scintillator crystal. The use of an array of SDDs provides a high quantum efficiency for the detection of the scintillation light together with a very low electronics noise. A very compact detection module based on the use of integrated readout circuits was developed. The performances achieved in gamma-ray imaging using this camera are reported here. When imaging a 0.2 mm collimated (57)Co source (122 keV) over different points of the active area, a spatial resolution ranging from 0.25 to 0.5 mm was measured. The depth-of-interaction capability of the detector, thanks to the use of a Maximum Likelihood reconstruction algorithm, was also investigated by imaging a collimated beam tilted to an angle of 45 degrees with respect to the scintillator surface. Finally, the imager was characterized with in vivo measurements on mice, in a real preclinical environment
Passive protections against breakdown effects in Neutral Beam injection devices for nuclear fusion experiments
No full textThe necessity of new and clean technologies for energy production from one hand and the carbon dioxide emission regulations on the other are inducing nuclear fusion research to speed towards a possible future energy source. So the next experiment, which is being built in France, called ITER (acronym for International Thermonuclear Experimental Reactor, an international collaboration between European Union, Japan, Russian Federation, India, China, South Korea and United States of America) has to give an answer on the real feasibility to achieve nuclear fusion, and in particular on the possibility to control the plasma stability for long time at high temperature, to maintain the stationary phase and to reach fusion temperature. One of the components necessary to heat the plasma is the Neutral Beam Injector; the concept has been developed for many years up to the present experiments. The principle is basic: the plasma is hit by a neutral atoms beam (not affected by the high magnetic field of the system) at high kinetic energy so that this energy is transferred by collisions to the ions of the plasma. Meanwhile the beam helps to drive the plasma current, necessary for the plasma confinement inside the vessel in a “tokamak” configuration. The engineering requirements for the ITER NBI are very demanding, as it is subjected by severe mechanical, thermic and electrical stress. In particular, the neutral beam power requested is 16.5 MW while the energy of the deuterium or hydrogen negative ions, accelerated before neutralization, is in the order of 1 MeV. This involves a total accelerating voltage equal to 1 MV. So one of the most critical topic for the whole system is the operation very close to the breakdown limits for the accelerating grids, so that breakdown is not considered as a fault but a common working condition for the system. The activity reported in this doctoral thesis, mainly carried out at Consorzio RFX, deals on this matter. In particular the effects of arc between the grids are analyzed, both in terms of arc energy deposition on the grids and in terms of the current and voltage transient propagation on different locations of the system. Arc energy has to be limited below a certain threshold value in order to avoid an irreversible grids damage; this would cause the de-conditioning and the loss of high voltage holding with a breakdown occurrence at lower voltage level. Instead the fast voltage transients are dangerous because they can induce overvoltages on some tricky points and therefore lead to unexpected insulation losses; in addition they are source of electromagnetic noise (EMI) due to high frequencies in the order of MHz, a problem if we consider the large number of diagnostic devices. In this thesis some design solutions to limit these effects are explained; they are supported by proper circuital simulations or experimental validation. The devices presented are alternative to the present adopted solutions, as they form a comprehensive protection strategy. Then, they are passive protections because we need an instantaneous intervention after breakdown to be effective, contrary to active protections which need some delay due to the signal acquisition demonstrating the arc occurrence. The thesis is organized as follows. In the chapter 1 the ITER neutral beam injector is presented, in the framework of the nuclear fusion research; the operation principles and the main components are basically described. Finally the test facility being built in Padua is shown; it is constituted by two experiments, a ITER full-scale negative ion sources, with a single -100 kV accelerating stage, and a full-scale injector, identical to that which will be installed in ITER. The chapter 2 shows at first the operating conditions, from the electrical point of view, foreseen for the neutral beam injector. In particular high voltage holding issues are presented, together with the conditioning process in vacuum; then a tentative vacuum arc modeling for long gap is described, considering arc energy dissipation due mainly to radiation phenomenon. At last present countermeasures against breakdown effects are shown, namely a concentrated core snubber at the injector transmission line ends and the active protections. In the chapter 3 two new concepts for passive protections are introduced. The first is a damping resistor connecting the last accelerating grid (the so called grounded grid) with the vacuum vessel (grounded) of the injector with the aim to damp the arc current involving this grid and the return conductor of the transmission line. Then the design and the assembly of a prototype are described; this is installed at the French laboratory of CEA (Commissariat à l’Énergie Atomique) in Cadarache, where it will be tested. The detailed circuital modeling of this test bed is reported; the model is useful to compare and understand experimental results. The second device is a distributed core snubber along the whole transmission line to damp the breakdown with a less cumbersome element and a simpler, more effective structure. The results on a small-scale example are presented to support this proposal. The chapter 4 outlines an integration of a comprehensive design for passive protections on a whole system. In particular, for the experimental negative ion source the positive effects of some devices are proposed, studied and optimized, i.e. a damper resistor, a distributed core snubber and a L–R parallel input impedance between the power supply and the transmission line. Finally the core snubber design is described, constituted by a series of magnetic cores evenly distributed on the transmission line and polarized by a proper biasing circuit.L’esigenza di nuove tecnologie per la produzione di energia, compatibili con l’ambiente, e le normative sulle emissioni di anidride carbonica stanno spingendo la ricerca sulla fusione nucleare come possibile alternativa futura. Da questo punto di vista il prossimo esperimento in via di costruzione in Francia, ITER (acronimo di International Thermonuclear Experimental Reactor, frutto di una collaborazione internazionale tra Unione Europea, Giappone, Russia, India, Cina, Corea del Sud e Stati Uniti d’America), dovrà dare delle risposte sull’effettiva fattibilità della fusione nucleare, e in particolare sul controllo della stabilità di plasma per lunghi tempi e ad alte temperature, sulla possibilità di funzionamento in regime stazionario e sull’effettivo raggiungimento della temperatura di fusione. Uno dei dispositivi necessari per il riscaldamento del plasma è l’iniettore di neutri, concetto sviluppato già in diverse macchine operanti fino ad oggi. Il principio è semplice: si tratta di “bombardare” il plasma con un fascio di atomi neutri (quindi insensibili ai forti campi magnetici presenti) ad alta energia cinetica in modo da trasferire mediante collisioni l’energia agli ioni del plasma stesso. Nel contempo il fascio aiuta anche il ostenimento della corrente di plasma, necessaria per il confinamento nella camera di scarica in configurazione “tokamak”. Le prestazioni ingegneristiche richieste all’iniettore di neutri di ITER sono molto gravose, sia dal punto di vista delle sollecitazioni meccaniche e termiche che da quelle elettriche. In particolare, la potenza del fascio di atomi neutri richiesto è di 16.5 MW mentre l’energia di accelerazione del fascio di ioni negativi di deuterio o idrogeno, a monte della neutralizzazione, è di 1 MeV. La tensione di accelerazione corrispondente è perciò di 1 MV. Uno dei punti più critici dell’intero sistema è dato dalle condizioni operative molto vicine ai limiti di scarica per le griglie di accelerazione, tanto che la scarica stessa non è considerata un fenomeno di guasto bensì una normale condizione di funzionamento del sistema. Il lavoro esposto in questa tesi di dottorato, svolto principalmente presso il Consorzio RFX, si inserisce in questo contesto. In particolare vengono analizzati gli effetti dell’arco tra le griglie sia in termini di energia d’arco depositata sulle griglie stesse che dei transitori di tensione e corrente che si propagano nei vari punti del sistema. Riguardo all’energia d’arco, essa dev’essere limitata al di sotto di un certo valore per evitare il danneggiamento irreversibile delle griglie stesse con conseguente decondizionamento del sistema, perdita delle proprietà di tenuta della tensione e quindi il verificarsi della scarica a tensioni più basse. I transitori di tensione invece possono essere dannosi, sia perché possono indurre sovratensioni in punti delicati del sistema con conseguente perdita dell’isolamento, sia perché sono fonte di disturbi elettromagnetici (EMI) per le varie apparecchiature diagnostiche presenti, legati alle alte frequenze in gioco dell’ordine dei MHz. Vengono in questa sede proposte alcune soluzioni progettuali per limitare tali effetti, corroborate da opportune simulazioni circuitali o da validazione sperimentale. I dispositivi esposti sono alternativi a quelli fino ad oggi impiegati, presentando una strategia d’insieme per la protezione. In più, sono di tipo passivo in quanto devono intervenire istantaneamente al verificarsi della scarica per poter essere efficaci, contrariamente alle protezioni attive che necessitano di un certo tempo di intervento legato all’acquisizione di un segnale comprovante la scarica. La tesi è articolata nel modo seguente. Nel capitolo 1 viene introdotto l’iniettore di neutri di ITER nell’ambito delle ricerche sulla fusione nucleare; ne vengono descritti schematicamente i principi di funzionamento e i componenti principali. Infine viene presentata l’installazione sperimentale in via di costruzione a Padova, costituita da due esperimenti, ovvero una sorgente di ioni negativi in scala 1:1 rispetto a quella di ITER, con un unico stadio di accelerazione del fascio a -100 kV, e un iniettore vero e proprio, identico a quello che verrà installato su ITER. Il capitolo 2 presenta dapprima le condizioni operative previste per l’iniettore di neutri dal punto di vista elettrico. In particolare vengono introdotte le problematiche della tenuta alla tensione e del processo di condizionamento in vuoto; quindi viene descritta una possibile modellazione circuitale per l’arco elettrico su lunghe distanze, considerando il fenomeno dell’irraggiamento come preponderante per la dissipazione dell’energia d’arco. Infine vengono presentate le attuali soluzioni contro gli effetti della scarica, ovvero uno snubber magnetico concentrato alle estremità della linea di trasmissione dell’iniettore e le protezioni di tipo attivo. Nel capitolo 3 vengono introdotti due nuovi concetti di protezioni passive. Il primo è un resistore di smorzamento che collega l’ultima griglia di accelerazione del fascio di ioni (la griglia di terra) con la cassa esterna dell’iniettore (messa a terra) in modo da smorzare la corrente d’arco che interessa tale griglia e si richiude sul conduttore di ritorno della linea di trasmissione. Vengono descritti il progetto e la costruzione di un prototipo installato presso il laboratorio francese del CEA (Commissariat à l’Énergie Atomique) di Cadarache, dove dovrà essere testato. L’impianto di prova di tale laboratorio viene poi modellato nel dettaglio per poter confrontare i risultati sperimentali e poterli interpretare. Il secondo dispositivo è uno snubber magnetico distribuito lungo tutto lo sviluppo della linea di trasmissione, in modo da smorzare al meglio ogni possibile guasto con un minor ingombro sul sistema e una struttura più semplice ed efficace. I risultati di una prova sperimentale su un modello in scala ridotta sono presentati a supporto della proposta. Il capitolo 4 delinea un esempio di progetto integrato di protezioni passive su un intero sistema. In particolare, per l’esperimento della sorgente di ioni negativi, vengono proposti, studiati e ottimizzati su un opportuno circuito equivalente gli effetti positivi del resistore di smorzamento, dello snubber magnetico distribuito e di un’impedenza L–R parallelo interposta tra alimentatore e linea di trasmissione. Infine viene descritto il progetto dello snubber, costituito da una serie di nuclei magnetici equispaziati lungo la linea e polarizzati da un opportuno circuito
“Applications of the HICAM Gamma Camera”
No full textThe goal of the HICAM project, supported by the European Community, is the development of a new Anger camera for clinical and research environments and specific applications where high overall spatial resolution and system compactness are required. The camera is based on a matrix of Silicon Drift Detectors (SDDs) coupled to a CsI(Tl) crystal. Two prototypes were developed during the project, with 5x5 cm2 and 10x10 cm2 FOV. They provide a high intrinsic spatial resolution (<1mm), an overall spatial resolution of ~ 2.67 mm @ 4cm and appropriate sensitivity. The developed camera is compact, very versatile and has a potential to be employed in several imaging applications, for clinical studies on humans, for small organs imaging in adults and infants, or being incorporated in systems for both planar and SPECT acquisition for small animals studies.
In this paper we will describe the most significant results obtained so far with this new camera employed in several applications
iCaCoT: Interactive camera-based coaching and training
No full textThis paper reports on the evaluation of the concept of interactive camera-based coaching and training (iCaCoT), which focuses on using interactive video navigation for coaching and training purposes. The iCaCoT concept leverages tiled streaming technology, which allows users to navigate freely through high-resolution video feeds while minimising the bandwidth required, by only streaming the part of the video the user is interested in. iCaCoT gives a trainer the possibility to zoom in on her trainee while she is training and to focus on specific areas, both spatially and temporally. This concept becomes especially useful for training activities where the exact line followed by the trainee is not known beforehand (e.g. skiing, footballing), and thus where capturing the events using a static wide-angle camera located relatively far from action may be more convenient than a moveable close-up camera. We implemented the iCaCoT concept as an iPad application and demonstrated it with ski athletes in the popular ski location of Schladming, Austria. Our experiment shows that iCaCoT is a viable concept for ski training activities and that it gives interesting insights for future research directions.Intelligent SystemsElectrical Engineering, Mathematics and Computer Scienc
Evaluierung von sechs Fotofallenmodellen hinsichtlich der Eignung für Fang-Wiederfang Methoden beim Eurasischen Luchs (Lynx lynx)
No full textDigital outdoor cameras are increasingly used in wildlife research because they allow species inventories, population estimates, and behavior or activity observations. Which camera model is suitable and practical depends on environmental conditions, focus species and specific scientific questions posed. Here we focused on testing cameras appropriate for elusive species that can be identified visually owing to individual coat patterns. Specifically the camera should be adequate for calculating the minimum population of Eurasian Lynx (Lynx lynx) during a systematic monitoring with camera traps. Therefore we tested six digital camera models with regard to trigger speed and the image quality necessary for visual identification of pacing lynx on trails. The decision if a camera model is adequate for the scientific goal was regulated due to priority levels under laboratory conditions. Only one camera model proved to be suitable for camera-trap monitoring. Our practical camera test can be used to evaluate newer models of digital cameras as they become available. This application opens an avenue for a non-invasive population monitoring of rare and elusive species in a low mountain range area.Digitale Fotofallen werden weltweit in der Wildtierforschung eingesetzt. Die Einsatzgebiete sind vielfältig, sie reichen von Artenbestandsaufnahmen und Populationsschätzungen über die Verhaltensforschung bis hin zu Aktivitätsanalysen. Das jeweilig eingesetzte Kameramodell muss an die Aufnahmesituation und die Zielsetzung der Analyse angepasst sein. Das Ziel unseres Fotofallentests war es, ein Modell zu finden, welches für die visuelle Identifizierung von Fellmustern des Eurasischen Luchses geeignet ist. Die Fotofalle soll in einem systematischen Monitoring für die minimale Anzahl der im Gebiet vorkommenden Luchse und deren Populationsschätzung mit Fang-Wiederfang Methoden eingesetzt werden können. Bei dem Test von sechs Fotofallenmodellen, fiel das Hauptaugenmerk auf die Auslösegeschwindigkeit und die Bildqualität welche die nötigen Faktoren für die Sicherstellung der visuellen Identifikation von schreitenden Luchsen am Wildwechsel darstellen. Zur Entscheidungsfindung der Eignung eines Fotofallenmodells für die Fragestellung definierten wir Prioritätslevel unter Laborbedingungen. Es stellte sich heraus, dass nur ein Fotofallenmodell die Ansprüche erfüllte. Der praktische Fotofallentest kann für neuerscheinende Fotofallenmodelle adaptiert werden. Diese Anwendung eröffnet die Möglichkeit für ein nicht invasives Monitoring in Mittelgebirgslandschaften
Scale reduction in modeling landmine detection by IR Termography
No full textA method has been proposed to reproduce in the laboratory experiments of infrared landmine detection with reduced length- and time-scale. In this work, the method is verified experimentally. Models of landmines are purposely built by a rapid prototyping technique. The surface response of the soil-landmine system is then monitored by an infrared camera. Preliminarily, the response measured above full-scale models is cross-checked against that measured above actual landmines. Full-scale and reduced-scale models are subsequently tested outdoors and in the laboratory, respectively. The measured distribution and time-evolution patterns of surface temperature are eventually compared, in order to assess the reliability of the scale reduction method
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