Profilazione di software medicale in CUDA

Le GPU sono al centro dell’innovazione tecnologica caratterizzando il cuore dei supercomputer più potenti al mondo in ambito di HPC (High Performance Computing). Il loro utilizzo caratterizza le applicazioni informatiche che hanno maggiore impatto nella vita quotidiana di ognuno di noi, spaziando dall’Intelligenza Artificiale ad algoritmi di visualizzazione a monitor. Le immagini mediche derivanti dai dispositivi a raggi X sono spesso elaborate dalle GPU, sia per motivazioni di tempo che di risorse. Il difficile compito di identificare eventuali malattie, salvando potenzialmente una vita, necessita elaborazioni near-real-time e di alta qualità, solitamente caratterizzate da algoritmi dall’elevato livello di complessità computazionale. La progettazione e la modellazione di tali algoritmi per l’utilizzo delle GPU, non è un processo banale. Richiede competenze sulla struttura e sul funzionamento interno delle GPU, nonché solide conoscenze di programmazione parallela, talvolta anche matematiche al fine di comprendere il linguaggio utilizzato nei report scientifici. In questa tesi, si affronta l’utilizzo della GPU nella sua declinazione in ambito medico, grazie alla gentile collaborazione dell’azienda See Through s.r.l specializzata, tra le altre cose, nello sviluppo di software per dispositivi medici a raggi X. Nello specifico, si affronta la profilazione e l’ottimizzazione di un algoritmo di rimozione del rumore (in inglese, Denoising)

CIRCUIT AND CONTAINMENT ASPECTS OF PHÉBUS EXPERIMENTS FPT0 AND FPT1

The Phebus FP severe accident experiments FPT0 and FPT1 were performed at Institut de radioprotection et de sûreté nucléaire (IRSN, Radioprotection and Nuclear Safety Institute) Cadarache (France) in 1993 and 1996 respectively. In each test a 1 m long bundle of fuel rods plus a silver indium cadmium control rod was heated to an advanced state of degradation in the Phebus reactor, and the materials released were swept by an injected steam flow through a model circuit and into a miniature containment vessel. Test FPT0 used fresh fuel, while in FPT1 the fuel had a burnup of 23 GWd/tonne. In an international effort coordinated by the European Commission Joint Research Centre and IRSN intensive analytical study of data from the circuit and containment was performed using a variety of models and computer codes, seeking to reconcile the wide variety and copious quantity of online and post-test data available and to draw conclusions. The present consolidation report makes a critical survey of the degree of success achieved and draws conclusions as to where understanding can be considered good and where it appears necessary to perform further analytical work, factoring in both findings from other tests of the Phebus FP series and from other experimental programmes.JRC.F.5-Nuclear Reactor Safety Assessmen

Analysing the performance of radiological monitoring network during nuclear accidents

JRODOS was used to simulate the dispersion of airborne radioactive material from a point source over the period 2012–2015. In total, 1331 radioactive plumes were simulated with the objective to investigate the influence of changes in meteorological conditions in the performance of the monitoring network. For this purpose, the existing set of 84 monitoring stations included in the EUropean Radiological Data Exchange Platform (EURDEP) system in an area of 200 km around the source point is taken as reference. A methodology is presented for quantitative evaluation of the variability of the number of stations affected, the time of the first detection, the maximum registered and differences between the maximum values match in the network and in the simulated plumes. The results show seasonal differences in all of these parameters according to changes in the size and shape of the affected area due to meteorological conditions. There are large differences in the number of monitoring stations affected by the plumes, from 2 to 74; in the timing and location of the first alert given by the network, from 1 to more than 5 h and faster along the west-east axis from the source; and in level of maximum gamma dose rate detected by the monitoring stations, from 0.17 nSv/h in summer to 0.22 nSv/h in autumn. These results show the need to consider this type of analysis over the years in the design of monitoring networks and in the development of nuclear emergency preparedness and response (EP&R) plans

Simulation Study of Light-induced, Current-induced Degradation and Recovery on PERC Solar Cells

Abstract The way to permanently recover the well-known Light-Induced Degradation (LID) which affects the p-type Cz-Si PERC solar cells represents one of the main challenges of photovoltaic research. In this work we have set up a numerical simulations flow which allows us to reproduce the experimental measured values of figures of merit (FOMs) of four different Cz-PERC solar cells lots subjected to a degradation and two regeneration processes. The recombination centres in bulk and the Boron-Oxygen complexes (B-O) are modeled by means of two trap levels tuned on the basis of experimental data. From simulations we confirm that the FOM degradation levels off after 16hours and the regeneration process characterized by relatively long time process is preferred in terms of performance recovery. In addition, further cells with different passivation films are analyzed by adopting the same methodology

30 years of European Commission Radioactivity Environmental Monitoring Database (REMdb) – an open door to boost environmental radioactivity research

Abstract. The Radioactivity Environmental Monitoring data bank (REMdb) was created in the aftermath of the Chernobyl accident (1986) by the European Commission (EC) – Directorate-General Joint Research Centre (DG JRC), sited in Ispra (Italy). Since then it has been maintained there with the aim to keep a historical record of the Chernobyl accident and to store the radioactivity monitoring data gathered through the national environmental monitoring programs of the member states (MSs). The legal basis is the Euratom Treaty, Chapter III Health and Safety, Articles 35 and 36, which clarify that MSs shall periodically communicate to the EC information on environmental radioactivity levels. By collecting and validating this information in REMdb, JRC supports the DG for Energy in its responsibilities in returning qualified information to the MSs (competent authorities and general public) on the levels of radioactive contamination of the various compartments of the environment (air, water, soil) on the European Union scale. REMdb accepts data on radionuclide concentrations from EU MSs in both environmental samples and foodstuffs from 1984 onwards. To date, the total number of data records stored in REMdb exceeds 5 million, in this way providing the scientific community with a valuable archive of environmental radioactivity topics in Europe. Records stored in REMdb are publicly accessible until 2011 through an unrestricted repository "REM data bank – Years 1984–2006" https://doi.org/10.2905/jrc-10117-10024 (De Cort et al., 2007) and "REM data bank – Years 2007–2011" https://doi.org/10.2905/de42f259-fafe-4329-9798-9d8fabb98de5 (De Cort et al., 2012). Access to data from 2012 onwards is granted only after explicit request, until the corresponding monitoring report is published. Each data record contains information describing the sampling circumstances (sampling type, begin and end time), measurement conditions (value, nuclide, apparatus, etc.), location and date of sampling, and original data reference. In this paper the scope, features and extension of REMdb are described in detail

Simulation Study of Multi-wire front Contact Grids for Silicon Solar Cells

Abstract Multi-wire (MW) front-contact schemes represent a promising alternative to standard H-pattern structure with ribbon busbar (BB) in silicon solar cells. In the case of MW schemes, busbar are replaced by copper wires. MW have been demonstrated to enhance the photo-generation with respect to a standard H-pattern structure with ribbon busbar when solar cells are encapsulated and assembled in modules. However, the influence of the geometrical and optical properties of the encapsulation layers as well as of wires on the optical effective shading is not exhaustively treated by the literature. In this work, we have performed electro-optical simulations of MW and BB based solar cells in order to calculate the effective optical shading factor, the enhancement of conversion efficiency and the saving of contact-paste, with respect to the BB design. Specifically, we have studied by means of a ray-tracing simulation tool the significant impact of the front contact grid geometry, of the encapsulation layer thickness and of the optical properties of the cell front interface on the effective optical shading. The calculated values of effective optical shading are used to determine the enhancement of the figures of merit and the paste saving with respect to the reference silver BB scheme. On the basis of our calculations the adoption of optimized MW designs may enhance the conversion efficiency up to 0.5% abs , allowing paste saving up to 50 mg per cell

A Comparative Study of MWT Architectures by Means of Numerical Simulations

AbstractIn order to improve the efficiency of c-Si and mc-Si solar cells, Metal Wrap Though (MWT) architecture is investigated. In this paper we implement TCAD numerical simulations to analyze the performance of MWT cells with a point busbar or a continuous busbar at the back side. The two topologies of MWT cells are compared in both illuminated and dark conditions, aiming at understanding and comparing the resistive and recombination losses. The impact of the separation region is also studied, highlighting the degradation effect on the Fill Factor (FF) and on the efficiency in the two structures. We observe that the separation region dimension leads to a higher degradation of efficiency in case of continuous busbar

The Influence of Perspective of an Inanimate Object on the Boundary Extension Phenomena [abstract only]

One of the most compelling phenomena in visual memory is the Boundary Extension (BE) which is the tendency to remember close-up scenes as if they include more information than that was seen. Intraub and Richardson (1989; JEP:LMC), suggested that this phenomenon is due to a filling in process: we fill the scene with information around the boundaries based on our knowledge. For the BE to occur, the scene must be perceived as part of a continuous environment. This project investigated whether the BE can be implicitly affected by the directional information provided by a camera. In the learning phase of a recognition experiment, participants were presented with an image on a computer screen that could have been cropped either to the left or to the right whilst a camera could have been positioned either to their left or right. In the testing phase, the image was then presented again, and participants were asked to judge if it was the same. Results showed that the BE magnitude reduces when the camera is in the same side of the cropped images. It is concluded that implicit directional cues can affect our ability to visually memorize images

The European Radiological Data Exchange Platform (EURDEP): 25 years of monitoring data exchange

Abstract. During the early phase of an accident with the release of radioactive material to the environment at the local or transboundary scale, a rapid and continuous system of information exchange, including real-time monitoring data to competent authorities and the public, is critical for setting up countermeasures. This information and data exchange must be carried out in a harmonized and consistent manner to facilitate its interpretation and analysis. After the Chernobyl accident in 1986, and in order to avoid the competent authorities being unprepared again for a similar event, the European Commission (EC) defined and put in place a directive (Council Decision 87/600/EURATOM, 1987) which essentially obliges a member state that decides to implement widespread countermeasures to protect its population to notify the European Commission without delay. The same Council Decision also specifies that the results of radiological monitoring must be made available to the European Commission and all potentially affected member states. Over the past 30 years, the European Commission has invested resources in developing and improving a complete system to carry out this delicate task, currently composed of two platforms: the European Community Urgent Radiological Information Exchange (ECURIE) and the European Radiological Data Exchange Platform (EURDEP). This paper aims to increase knowledge of the latter system as a valuable tool for understanding and analysing the radioactivity levels in Europe. Commencing with background information, in this paper, we will describe the EURDEP system in detail, with an emphasis on its status, data availability, and how these data are diffused depending on the audience. Within the scope of this publication, we describe an example of measurements available in the EURDEP system, which to be used for scientific purposes. We provide two complete datasets (air-concentration samples – https://doi.org/10.2905/23CBC7C4-4FCC-47D5-A286-F8A4EDC8215F; De Cort et al., 2019a; and gamma dose rates – https://doi.org/10.2905/0F9F3E2D-C8D7-4F46-BBE7-EACF3EED1560; De Cort et al., 2019b) for the recent radiological release of 106Ru in Europe, which occurred between the end of September and early October 2017. Records stored are publicly accessible through an unrestricted repository called COLLECTION belonging to the JRC Data Public Catalogue (https://data.jrc.ec.europa.eu, last access: 1 July 2019)