About the development of visual search algorithms and their hardware implementations

2015 - 2016The main goal of my work is to exploit the benefits of a hardware implementation of a 3D visual search pipeline. The term visual search refers to the task of searching objects in the environment starting from the real world representation. Object recognition today is mainly based on scene descriptors, an unique description for special spots in the data structure. This task has been implemented traditionally for years using just plain images: an image descriptor is a feature vector used to describe a position in the images. Matching descriptors present in different viewing of the same scene should allows the same spot to be found from different angles, therefore a good descriptor should be robust with respect to changes in: scene luminosity, camera affine transformations (rotation, scale and translation), camera noise and object affine transformations. Clearly, by using 2D images it is not possible to be robust with respect to the change in the projective space, e.g. if the object is rotated with respect to the up camera axes its 2D projection will dramatically change. For this reason, alongside 2D descriptors, many techniques have been proposed to solve the projective transformation problem using 3D descriptors that allow to map the shape of the objects and consequently the surface real appearance. This category of descriptors relies on 3D Point Cloud and Disparity Map to build a reliable feature vector which is invariant to the projective transformation. More sophisticated techniques are needed to obtain the 3D representation of the scene and, if necessary, the texture of the 3D model and obviously these techniques are also more computationally intensive than the simple image capture. The field of 3D model acquisition is very broad, it is possible to distinguish between two main categories: active and passive methods. In the active methods category we can find special devices able to obtain 3D information projecting special light and. Generally an infrared projector is coupled with a camera: while the infrared light projects a well known and fixed pattern, the camera will receive the information of the patterns reflection on a certain surface and the distortion in the pattern will give the precise depth of every point in the scene. These kind of sensors are of i i “output” — 2017/6/22 — 18:23 — page 3 — #3 i i i i i i 3 course expensive and not very efficient from the power consumption point of view, since a lot of power is wasted projecting light and the use of lasers also imposes eye safety rules on frame rate and transmissed power. Another way to obtain 3D models is to use passive stereo vision techniques, where two (or more) cameras are required which only acquire the scene appearance. Using the two (or more) images as input for a stereo matching algorithm it is possible to reconstruct the 3D world. Since more computational resources will be needed for this task, hardware acceleration can give an impressive performance boost over pure software approach. In this work I will explore the principal steps of a visual search pipeline composed by a 3D vision and a 3D description system. Both systems will take advantage of a parallelized architecture prototyped in RTL and implemented on an FPGA platform. This is a huge research field and in this work I will try to explain the reason for all the choices I made for my implementation, e.g. chosen algorithms, applied heuristics to accelerate the performance and selected device. In the first chapter we explain the Visual Search issues, showing the main components required by a Visual Search pipeline. Then I show the implemented architecture for a stereo vision system based on a Bio-informatics inspired approach, where the final system can process up to 30fps at 1024 × 768 pixels. After that a clever method for boosting the performance of 3D descriptor is presented and as last chapter the final architecture for the SHOT descriptor on FPGA will be presented. [edited by author]L’obiettivo principale di questo lavoro e’ quello di esplorare i benefici di una implementazione hardware per una pipeline di visual search 3D. Il termine visual search si riferisce al problema di ricerca di oggetti nell’ambiente. L’object recognition ai giorni nostri e’ principalmente basato sull’uso di descrittori della scena, una descrizione univoca per i punti salienti. Questo compito e’ stato implementato per anni utilizzando immagini: il descrittore di un punto dell’immagine e’ un semplice vettore di caratteristiche. Accoppiando i descrittori presenti in differenti viste della stessa scena permette di trovare punti nello spazio visibili da entrambe le viste. Chiaramente, utilizzando immagini 2D non e’ possibile avere descrittori che sono robusti a cambiamenti della prospettiva, per questo motivo, molte tecniche sono state proposte per risolvere questo problema utilizzando descrittori 3D. Questa categoria di descrittori si avvale di 3D point cloud e mappe di disparita’. Ovviamente tecniche piu’ sofisticate sono necessarie per ottenere la rappresentazione 3D della scena. Il campo dell’acquisizione 3D e’ molto vasto ed e’ possibile distinguere tra due categorie di sensori: sensori attivi e passivi. Tra i sensori attivi possiamo annoverare dispositivi in grado di proiettare un pattern di luce infrarossa sulla scena, questo pattern noto presenta delle variazioni dovute agli oggetti presenti nella scena. Una camera infrarossi riceve l’immagine distorta del pattern e deduce la geometria della scena. Questo tipo di dispositivi non sono molto efficienti dal punto di vista energetico dato che un sacco di corrente viene consumata per proiettare il pattern. Un altro modo per ottenere un modello 3D e’ quello di usare sensori passivi, una coppia di telecamere puo’ essere utilizzata per ottenere informazioni utilizzando metodi di triangolazione. Questi metodi pero’ richiedono un sacco di potenza computazionale nel caso di applicazioni real time, per questo motivo e’ necessario utilizzare dispositivi ad-hoc quali architetture hardware dedicate implementate mediante l’uso di FPGA e ASIC. In questo lavoro ho esplorato gli step principali di una pipeline per la visual search composta da un sistema di visione 3D e uno per la descrizione di punti. Entrambi i sistemi si avvalgono di achitetture hardware dedicate prototipate in RTL e implementate su FPGA. Questo e’ un grosso campo di lavoro e provo ad esplorare i benefici di una implementazione harwadere per l’accelerazione degli algoritmi stessi e il risparmi di energia elettrica. [a cura dell'autore]XV n.s

Assessment and verification of mean effective diameter of internal channels fabricated by laser powder bed fusion

Abstract Channels with small diameters, used for example in conformal cooling, can nowadays be fabricated by laser powder bed fusion. Measurements of the mean effective diameter and surface topography are important to quantify the flow capabilities through the channel. In this paper, a new method using X-ray computed tomography is developed to obtain the mean effective diameter and mean surface topography height. The developed method is verified by determining the mean effective diameter using incompressible turbulent fluid flow simulations, whereupon the determined mean surface topography height is fed as an input to the simulation. The method is proved to offer a non-destructive and relatively fast approach to measure the mean effective diameter and mean surface topography height in circular channels

Characterization of gas phase iron phthalocyanine with X-ray photoelectron and absorption spectroscopies

Despite the numerous studies dedicated to phthalocyanine molecules adsorbed on surfaces, in monolayer or thin film, very few works have been focused on the characterization of vapors of these molecules. In this article we present the C 1s, N 1s and Fe 2p photoemission results as well as N K-edge X-ray absorption data of iron phthalocyanine (FePc) in gas phase. Presented comparison of X-ray photoelectron spectroscopy and X-ray absorption spectroscopy spectra of FePc films show a great similarity with the gas phase results, con- firming the molecular character of thick films. The Fe 2p photoemission spectrum of the gas phase FePc, shown for the first time, can be considered as a fingerprint of the Fe(II) ionic state of the central metal of the iron phthalocyanine. The performed multiplet calculations for describing the Fe 2p XP spectrum indicate 3 Eg (a1g 2 eg 3 b2g 1 ) state as the most probable ground state for thick film of iron phthalocyanine

Elucidating the 3d Electronic Configuration in Manganese Phthalocyanine

To shed light on the metal 3d electronic structure of manganese phthalocyanine, so far controversial, we performed photoelectron measurements both in the gas phase and as thin film. With the purpose of explaining the experimental results, three different electronic configurations close in energy to one another were studied by means of density functional theory. The comparison between the calculated valence band density of states and the measured spectra revealed that in the gas phase the molecules exhibit a mixed electronic configuration, while in the thin film, manganese phthalocyanine finds itself in the theoretically computed ground state, namely, the b12ge3ga1gb01g electronic configuration

Epidemiology, pathological aspects and genome heterogeneity of feline morbillivirus in Italy

Feline morbillivirus (FeMV) is an emerging morbillivirus first described in cats less than a decade ago. FeMV has been associated with chronic kidney disease of cats characterized by tubulointerstitial nephritis (TIN), although this aspect is still controversial and not demonstrated with certainty. To investigate FeMV prevalence and genomic characteristics, an epidemiological survey was conducted in a total number of 127 household cats originating from two Italian regions, Abruzzi and Emilia-Romagna. A total number of 69 cats originating from three feline colonies were also enrolled for the study. Correlation with TIN was investigated by employing a total number of 35 carcasses. Prevalence of FeMV RNA was higher in urine samples collected from cats of colonies (P = 31.8%, CI 95% 22.1–43.6) compared to household cats (P = 8.66%, CI 95% 4.9–14.9) and in young and middle-aged cats while prevalence of FeMV Abs was higher in old cats. Sequences obtained straight from infected biological samples, either partial or complete, cluster into two clades within FeMV genotype 1, distantly related to FeMV genotype 2. Immunohistochemistry analysis of kidney sections of FeMV RNA positive cats revealed immunoreactivity within epithelial cells of renal tubuli and inflammatory cells. However, statistically significant association between FeMV and renal damages, including TIN, was not demonstrated (p= 0.0695, Fisher exact test). By virus histochemistry performed with FeMV-negative feline tissues and a FeMV isolate, tropism for different cellular types such as inflammatory cells residing in blood vessels of kidney and brain, airway epithelial cells, alveolar macrophages and to a lesser extent, the central nervous system, was demonstrated. Additional studies are warranted in order to establish viral tropism and immune response during the early phases of infection and to disentangle the role of FeMV in co-infection processes

The 10B(p,α)7Be S(E)-factor from 5 keV to 1.5 MeV using the Trojan Horse Method

The 10 B(p, α ) 7 Be reaction is the main responsible for the 10 B destruction in stellar interior [1]. In such environments this p-capture process occurs at a Gamow energy of 10 keV and takes places mainly through a resonant state (Ex = 8.701 MeV) of the compound 11 C nucleus. Thus a resonance right in the region of the Gamow peak is expected to significantly influence the behavior of the astrophysical S(E)-factor. The 10 B(p, α ) 7 Be reaction was studied via the Trojan Horse Method (THM) applied to the 2 H( 10 B, α 7 Be)n in order to extract the astrophysical S(E)-factor in a wide energy range from 5 keV to 1.5 MeV

ECMO for COVID-19 patients in Europe and Israel

Since March 15th, 2020, 177 centres from Europe and Israel have joined the study, routinely reporting on the ECMO support they provide to COVID-19 patients. The mean annual number of cases treated with ECMO in the participating centres before the pandemic (2019) was 55. The number of COVID-19 patients has increased rapidly each week reaching 1531 treated patients as of September 14th. The greatest number of cases has been reported from France (n = 385), UK (n = 193), Germany (n = 176), Spain (n = 166), and Italy (n = 136) .The mean age of treated patients was 52.6 years (range 16–80), 79% were male. The ECMO configuration used was VV in 91% of cases, VA in 5% and other in 4%. The mean PaO2 before ECMO implantation was 65 mmHg. The mean duration of ECMO support thus far has been 18 days and the mean ICU length of stay of these patients was 33 days. As of the 14th September, overall 841 patients have been weaned from ECMO support, 601 died during ECMO support, 71 died after withdrawal of ECMO, 79 are still receiving ECMO support and for 10 patients status n.a. . Our preliminary data suggest that patients placed on ECMO with severe refractory respiratory or cardiac failure secondary to COVID-19 have a reasonable (55%) chance of survival. Further extensive data analysis is expected to provide invaluable information on the demographics, severity of illness, indications and different ECMO management strategies in these patients

Sicilia—silicon carbide detectors for intense luminosity investigations and applications

Silicon carbide (SiC) is a compound semiconductor, which is considered as a possible alternative to silicon for particles and photons detection. Its characteristics make it very promising for the next generation of nuclear and particle physics experiments at high beam luminosity. Silicon Carbide detectors for Intense Luminosity Investigations and Applications (SiCILIA) is a project starting as a collaboration between the Italian National Institute of Nuclear Physics (INFN) and IMM-CNR, aiming at the realization of innovative detection systems based on SiC. In this paper, we discuss the main features of silicon carbide as a material and its potential application in the field of particles and photons detectors, the project structure and the strategies used for the prototype realization, and the first results concerning prototype production and their performance