Influence of the Leakage Current on the Performance of Large Area Silicon Drift Detectors

In this paper we investigate the influence of the leakage current on the performance of Silicon Drift Detectors. First, analytical considerations are given in order to highlight the problems, specific for this type of detector, that emerge with leakage current. Then the obtained results are compared with the data of laboratory measurements. Aiming at a mass production of SDDs for the Inner Tracking System of the ALICE experiment at LHC we propose a simple and fast measurement for a preliminary selection before passing to a detailed acceptance test

Propagation of semantic information between orthophoto and 3D replica: a H-BIM system for the north transept of Pisa Cathedral

This contribution proposes a methodological approach for the transfer of annotations between orthophotos and 3D digital heritage models, relying on a mesh-based/point-based representation. The workflow leverages on the exploitation of 2D/3D projective relations and on the identification, propagation, modelling and tiling of virtual models of architectural heritage. Referring to the significant case study of Pisa Cathedral, the method is tested to ensure an informative continuum between 2D medias and 3D representations, in terms of morphology, geometry and semantic enrichment. At first, a high resolution ortho-photo is created to support studies related to conservation and restoration, e.g. to highlight degradation patterns and materials as well as to distinguish cracks, frescoed surfaces, decorations. Then, the information is translated from the 2D support to a virtual 3D mockup: this step is essential to ensure a complete understanding of the architectural heritage object, that can thus be studied in its entirety, considering its morphological complexities. The proposed approach provides a more effective system for the transfer and exchange of semantic information from high-resolution orthophotos to semantically rich 3D models, that can be fundamental even in view of the construction of Heritage-Building Information Modeling (H-BIM) environments

ACCURACY ASSESSMENT IN STRUCTURE FROM MOTION 3D RECONSTRUCTION FROM UAV-BORN IMAGES: THE INFLUENCE OF THE DATA PROCESSING METHODS

The evolution of Structure from Motion (SfM) techniques and their integration with the established procedures of classic stereoscopic photogrammetric survey have provided a very effective tool for the production of three-dimensional textured models. Such models are not only aesthetically pleasing but can also contain metric information, the quality of which depends on both survey type and applied processing methodologies. An open research topic in this area refers to checking attainable accuracy levels. The knowledge of such accuracy is essential, especially in the integration of models obtained through SfM with other models derived from different sensors or methods (laser scanning, classic photogrammetry ...). Accuracy checks may be conducted by either comparing SfM models against a reference one or measuring the deviation of control points identified on models and measured with classic topographic instrumentation and methodologies. This paper presents an analysis of attainable accuracy levels, according to different approaches of survey and data processing. For this purpose, a survey of the Church of San Miniato in Marcianella (Pisa, Italy), has been used. The dataset is an integration of laser scanning with terrestrial and UAV-borne photogrammetric surveys; in addition, a high precision topographic network was established for the specific purpose. In particular, laser scanning has been used for the interior and the exterior of the church, with the exclusion of the roof, while UAVs have been used for the photogrammetric survey of both roof, with horizontal strips, and façade, with vertical strips

‘Vita in omnia pervenit’. Eriugena’s Vitalism and the Influence of Marius Victorinus

Los mismos pasajes de Mario Victorino, Adversus Arium, III y IV, que parecen –según las comparaciones propuestas en las secciones precedentes de este estudio– haber inspirado a Eriúgena las principales ideas de vitalismo que apoya en su Comentario Dionisíaco y en el Libro III del Periphyseon, también han influido en una página del Libro V relativa a la vida de las criaturas en la Palabra de Dios. Aquí Eriúgena presenta una exégesis de Juan 1:3-4, que, aunque toma prestados varios elementos de Agustín, está al mismo tiempo marcado por las concepciones de Mario Victorino que habían sido rechazadas por el obispo de Hipona. La continuación del texto del Adv.Ar. IV, que expone la escala ascendente de los actos del mundo sublunar a las realidades supracelestes (12:13 y ss.), proporcionó, con ciertas reinterpretaciones, la base para otro pasaje de Periph. III, que trata de la existencia eterna de todas las cosas en la Sabiduría divina. Eriúgena sin duda también lo usó para atribuir al alma humana, en las Exposiciones en Ier. Coel., el adjetivo autokinetos, que encontró en Dionisio, refiriéndose a la primera jerarquía angélica. Finalmente, esta página de Mario Victorino, algunas líneas del desarrollo anterior sobre la vida universal y un texto del libro 1 del Adv. Ar. sobre el “descensio” del Logos son las fuentes de la primera parte del poema eriugeniano “Mystica sanctorum” (II, V, Traube). En la conclusión de la obra, tras un cuadro sinóptico de las referencias de los principales textos comparativos –cuyo paralelismo se ha señalado por primera vez en este estudio– se presentan algunas consideraciones generales sobre la importantísima influencia que la obra de Mario Victorino parece haber ejercido sobre Eriúgena y sobre sus consecuencias para la originalidad del pensador irlandés y el tipo específico de neoplatonismo que marcó su elaboración del dogma cristiano.   [El presente trabajo es la segunda parte del artículo. Para ver la primera parte: Vol. 7 (1986)]The same passages of Marius Victorinus, Adversus Arium, III and IV, which seem –according to the comparisons proposed in the preceding sections of this study– to have inspired Eriugena the main ideas of vitalism that he supports in his Dionysian Commentary and in Book III of the Periphyseon, have also influenced a page in Book V concerning the life of creatures in the Word of God. Here Eriugena presents an exegesis of John 1:3-4, which, although it borrows several elements from Augustine, is at the same time marked by Marius Victorinus’ conceptions that had been rejected by the Bishop of Hippo. The continuation of the text of Adv. IV, which exposes the ascending scale of the acts of the sublunar world to the supracelestial realities (12:13 ff.), provided, with certain reinterpretations, the basis for another passage in Periph. III, which deals with the eternal existence of all things in the divine Wisdom. Eriugena no doubt also used it to attribute to the human soul, in the Exposition in Ier. Coel. the adjective autokinetos, which he found in Dionysus, referring to the first angelic hierarchy. Finally, this page by Marius Victorinus, some lines of the previous development on universal life and a text from book 1 of the Adv. Ar. on the “descent” of the Logos are the sources of the first part of the Eriugenian poem “Mystica sanctorum” (II, V, Traube). In the conclusion of the work, after a synoptic table of the references of the main comparative texts –whose parallelism has been pointed out for the first time in this study– some general considerations are presented on the very important influence that the work of Marius Victorinus seems to have had on Eriugena and on its consequences for the originality of the Irish thinker and the specific type of Neo-platonism that marked his elaboration of Christian dogma.   [This is the second part of the article. To see the first one: Vol. 7 (1986)

CONNECTING GEOMETRY AND SEMANTICS VIA ARTIFICIAL INTELLIGENCE: FROM 3D CLASSIFICATION OF HERITAGE DATA TO H-BIM REPRESENTATIONS

Cultural heritage information systems, such as H-BIM, are becoming more and more widespread today, thanks to their potential to bring together, around a 3D representation, the wealth of knowledge related to a given object of study. However, the reconstruction of such tools starting from 3D architectural surveying is still largely deemed as a lengthy and time-consuming process, with inherent complexities related to managing and interpreting unstructured and unorganized data derived, e.g., from laser scanning or photogrammetry. Tackling this issue and starting from reality-based surveying, the purpose of this paper is to semi-automatically reconstruct parametric representations for H-BIM-related uses, by means of the most recent 3D data classification techniques that exploit Artificial Intelligence (AI). The presented methodology consists of a first semantic segmentation phase, aiming at the automatic recognition through AI of architectural elements of historic buildings within points clouds; a Random Forest classifier is used for the classification task, evaluating each time the performance of the predictive model. At a second stage, visual programming techniques are applied to the reconstruction of a conceptual mock-up of each detected element and to the subsequent propagation of the 3D information to other objects with similar characteristics. The resulting parametric model can be used for heritage preservation and dissemination purposes, as common practices implemented in modern H-BIM documentation systems. The methodology is tailored to representative case studies related to the typology of the medieval cloister and scattered over the Tuscan territory

Radiation Damage Studies of Silicon Photomultipliers

We report on the measurement of the radiation hardness of silicon photomultipliers (SiPMs) manufactured by Fondazione Bruno Kessler in Italy (1 mm$^2$ and 6.2 mm$^2$), Center of Perspective Technology and Apparatus in Russia (1 mm$^2$ and 4.4 mm$^2$), and Hamamatsu Corporation in Japan (1 mm$^2$). The SiPMs were irradiated using a beam of 212 MeV protons at Massachusetts General Hospital, receiving fluences of up to $3 \times 10^{10}$ protons per cm$^2$ with the SiPMs at operating voltage. Leakage currents were read continuously during the irradiation. The delivery of the protons was paused periodically to record scope traces in response to calibrated light pulses to monitor the gains, photon detection efficiencies, and dark counts of the SiPMs. The leakage current and dark noise are found to increase with fluence. Te leakage current is found to be proportional to the mean square deviation of the noise distribution, indicating the dark counts are due to increased random individual pixel activation, while SiPMs remain fully functional as photon detectors. The SiPMs are found to anneal at room temperature with a reduction in the leakage current by a factor of 2 in about 100 days.Comment: 35 pages, 25 figure

3-DIMENSIONAL GEOMETRIC SURVEY AND STRUCTURAL MODELLING OF THE DOME OF PISA CATHEDRAL

This paper aims to illustrate the preliminary results of a research project on the dome of Pisa Cathedral (Italy). The final objective of the present research is to achieve a deep understanding of the structural behaviour of the dome, through a detailed knowledge of its geometry and constituent materials, and by taking into account historical and architectural aspects as well. A reliable survey of the dome is the essential starting point for any further investigation and adequate structural modelling. Examination of the status quo on the surveys of the Cathedral dome shows that a detailed survey suitable for structural analysis is in fact lacking. For this reason, high-density and high-precision surveys have been planned, by considering that a different survey output is needed, according both to the type of structural model chosen and purposes to be achieved. Thus, both range-based (laser scanning) and image-based (3D Photogrammetry) survey methodologies have been used. This contribution introduces the first results concerning the shape of the dome derived from surveys. Furthermore, a comparison is made between such survey outputs and those available in the literature

INDOOR PHOTOGRAMMETRY USING UAVS WITH PROTECTIVE STRUCTURES: ISSUES AND PRECISION TESTS

Abstract. Management of disaster scenarios requires applying emergency procedures ensuring maximum safety and protection for field operators. Actual conditions of disaster sites are labelled as "Triple-D: Dull, Dusty, Dangerous" areas. It is well known that in this kind of areas and situations remote surveying systems are at their very best effective, and among these UAVs currently are an effective and performing field tool. Indoor spaces are a particularly complex scenario for this kind of surveys. In this case, technological advances currently offer micro-UAV systems, featuring 360° protective cages, which are able to collect video streams while flying in very tight spaces. Such cases require manual control of the vehicle, with the operator piloting the aircraft without prior knowledge of the status quo of the survey object and therefore without prior planning of flight paths. A possible benefit in terms of knowledge of the survey object could lay in the creation of a 3D model based on images extracted by video streams; to date, widely tested methods and techniques are available for processing UAV-borne video streams to obtain such models. Anyway, the protective cage and the need to use, in these operating conditions, wide-angle lenses presents some issues linked to ever-changing image framing, due to the presence of the cage wires on the field of view. The present work focused on this issue. Using this type of UAVs, video streams have been collected in different environments, both indoors and outdoors, testing several procedures for photogrammetric processing in order to assess the ability to create 3D models. These have been tested for reliability based on data collection conditions, also assessing the level of automation and speed attainable in post-processing. The present paper describes the different tests carried out and the related results.</p