Добірка наукової літератури з теми "Threedimensional representation"

By using a continuum modeling approach based on the equivalent elliptical crack representation of a local damage and the strain energy equivalence principle, the effective elastic compliances and the effective engineering constants are derived in closed forms in terms of the virgin (undamaged) elastic properties and a scalar damage variable for damaged two- and threedimensional isotropic solids. It is shown that the effective Young’s modulus in the direction normal to the crack surfaces is always smaller than its intact value.

In this article the setup and working principle of a new telecollaboration system “blue-c” is described. This system is an attempt to meet the rising expectations from industry of an IT-supported telecollaboration system. One basic requirement is that a three-dimensional representation of objects be possible together with threedimensional representations of the remote users. Since gesture and mimicry represent an important information channel during a discussion, a realistic 3D video representation is used instead of simple animated avatars. A simultaneous projection and image acquisition of the user in a telecollaboration system is necessary to allow simultaneous work of all team members. Thus, in the introduced system, problems had to be overcome such as providing, simultaneously, illumination for the image acquisition by the cameras and darkness for a bright projection to be seen by the user. A new approach was taken to integrate the cameras into the system by placing them behind active projection walls, which can be switched from transparent to opaque electrically. Unlike other systems, the cameras are therefore not visible to the user, who thus behaves more naturally. In addition, since the cameras are placed outside of the projection room, there is more space to move inside the immersive environment. The article describes the technology and functionality of the system, as well as the gathered experiences.

This article argues that the analysis of a threedimensional image demanded a three-dimensional approach. The authors realise that discussions of images and image processing inveterately conceptualise representation as being flat, static, and finite. The authors recognise the need for a fresh acuteness to three-dimensionality as a meaningful – although problematic – element of visual sources. Two dramatically different examples are used to expose the shortcomings of an ingrained two-dimensional approach and to facilitate a demonstration of how modern (digital) techniques could sanction new historical/anthropological perspectives on subjects that have become all too familiar. Each example could not be more different in their temporal and geographical location, their cultural resonance, and their historiography. However, in both these visual spectacles meaning is polysemic. It is dependent upon the viewer's spatial relationship to the artifice as well as the spirito-intellectual viewer within the community. The authors postulate that the multi- faceted and multi-layered arrangement of meaning in a complex image could be assessed by working beyond the limitations of the two-dimensional methodological paradigm and by using methods and media that accommodated this type of interconnectivity and representation.

The present paper analyses two cases exemplifying a possible use of survey and its elaborations in the field of conservation: the bell tower of the Basilica Santa Maria delle Vigne and the Chiesa di San Matteo, both situated in Genoa. In the first case, the threedimensional survey was used as a basis to build a model for the structural analysis. The need for an accurate database created with the three-dimensional survey allowed the research team to determine and highlight the critical points of the structure as the thickness of vaults and floors, the location of loads and the inclination of the walls. The data collected was used to create an accurate 3D model to be tested with simulations, in order to verify the stability of the bell tower when applying stress and limitations. In the second case, the three-dimensional survey was used as the basis for the collection, management and representation of the data derived from the survey on rising damp. The purpose was to test a dynamic data processing system that could be used as a tool to collect data on site as well as to access data remotely. By using software for three-dimensional representation and a node programming language, it was possible to define a system that offered dynamic viewing and was easy to use, through the use of chromatic scales and level curves, which can be generated starting from tables containing numerical data. Surveying, diagnostics, modelling and representation allow one to experiment with new ways of interaction within the common goal of conservation.

We consider the problem of reconstruction of an unknown characteristic interval and block transient thermal source inside a domain. By exploring the definition of an Extended Dirichlet to Neumann map in the time space cylinder that has been introduced in Roberty and Rainha (2010a), we can treat the problem with methods similar to that used in the analysis of the stationary source reconstruction problem. Further, the finite differenceθ-scheme applied to the transient heat conduction equation leads to a model based on a sequence of modified Helmholtz equation solutions. For each modified Helmholtz equation the characteristic interval and parallelepiped source function may be reconstructed uniquely from the Cauchy boundary data. Using representation formula we establish reciprocity functional mapping functions that are solutions of the modified Helmholtz equation to their integral in the unknown characteristic support. Numerical experiment for capture of an interval and an rectangular parallelepiped characteristic source inside a cubic box domain from boundary data are presented in threedimensional and one-dimensional implementations. The problem of centroid determination is addressed and questions are discussed from an computational points of view.

A concept of fuzzy three-dimensional Voronoi Diagram is presented for spatial relations analysis of real world three-dimensional geographical data, where it is an extension of well known two-dimensional Voronoi Diagram to three-dimensional representation with uncertain spatial relation information in terms of fuzzy set. It makes possible to analyze quantitatively complex boundaries of geographically intricate areas, to give human friendly fuzzy explanation of determining three-dimensional directions, and to express uncertain spatial relations by precise unified fuzzy description. It is applied to decide spatial direction relations of artificial geographicalmountain data, which includes 8 spatial directions with at most 60 relative direction relations, and it leads to detect threedimensional directions whereas the expression of traditional 4 directions and 12 relative directions indicate two-dimensional directions only. The proposed concept aims to discriminate neighbors’ class relations and spatial-temporal changes of specially appointed objects, and also aims to be a tool to achieve the intellective extraction and analysis of geographical data of a mountainous area located in northeast China.

Actually geometrics’ science offers new opportunities and interesting applications in the field of Cultural Heritage. These applications are strictly related to preservation, restoration but even to cataloging and reproducing a monument that no longer has its original integrity. The possibility of obtaining 3D data, of such a model close to reality, enables us to realize studies that sometimes are too complex or impossible. The paper will describe the study of a monumental arch, the Arco dei Gavi, built in Verona during the I sec. A.C., that was destroyed in 1805 by the Napoleonic army, and its wooden model that was realized in 1813 and it has a very important role concerning the monument’s reconstruction. The purpose is to realize two threedimensional models which can be comparable to each other, two models with recognizable differences, similarities and discontinuities about shapes and single elements that compose the monument. It should also be noted that some original parts of the monument have not been relocated but are badly preserved in a museum: the 3D digital model helps to identify these parts in their original location. The main steps of the work can be summarized in: collecting the historical documentation of Arco dei Gavi and its representations; identifying proper instruments (laser scanning and photogrammetric hardware and software); surveying the Arch and its wooden model; identifying a unique and shared reference system; comparing both digital models related to the same scale; choosing a three-dimensional representation to emphasize the results; reallocation of outstanding pieces (virtual anastylosis).

ABSTRACT This review aims to provide the reader with an overview of the potential clinical applications in three-dimensional (3D) Doppler ultrasound for the evaluation of vascularity and blood flow within the placenta. Significant innovations have recently occurred, improving the visualization and evaluation of placental vascularity, resulting from enhancements in delineation of tissue detail through electronic compounding and harmonics, as well as enhancements in signal processing of frequencyand/ or amplitude-based color Doppler ultrasound. Spatial representation of vascularity can be improved by utilizing 3D processing. Greater sensitivity of 3D Doppler ultrasound to macro- and microvascular flow has provided improved anatomical and physiologic assessment throughout pregnancy. The rapid development of these new sonographic techniques will continue to enlarge the scope of clinical applications in placental studies. Three-dimensional Doppler sonography is a unique ultrasound technique that enables assessment of vascular signals within the whole investigated area. Homodynamic changes included in the process of placentation are one of the most exciting topics in the investigation of early human development. How to cite this article Zalud I. Placental Blood Flow by Threedimensional Doppler Ultrasound. Donald School J Ultrasound Obstet Gynecol 2016;10(1):55-62.

This study focuses to understand the differences in reporting the same of The South China Seaterritorial dispute by two international news websites namely The New York Times and China Dailyand to exposed the hidden ideology behind the representation of those news websites. ThreeDimensional Framework by Fairclough in Critical Discourse Analysis were used in this study alongwith Systemic Functional Grammar particularly in transitivity analysis. The articles in this study werecollected from China Daily and The New York Times news website. The finding revealed that bothnews websites reported the issue of territorial dispute using material process and verbal processdominantly but The New York Times dominantly use material process more than China Daily. Next,the study found out that China Daily depicted the act of Beijing saying that territorial dispute as anormal thing due to the area of water are belong to China while The New York Times depicted the actof China as a violation of Sea rules of navigation in responding the territorial dispute. Last, the resultof this study found that China Daily stated in its news about how the US presence as meddling in thedisputed area of The South China Sea while The New York Times stated that the act of China inresponding the dispute is a harsh attitude and violating the rules. To sum up the study, thecombination of both theories is somehow useful in the discourse to expose the hidden meaning andideology.Keywords: Constrastive study, territorial dispute, three dimensional framework

L’attività di ricerca si è sviluppata con l’obiettivo di sperimentare i metodi e le tecniche di acquisizione, gestione e rappresentazione tridimensionale mediante l’uso del laser scanner per offrire un valido supporto alla documentazione e alla diagnostica finalizzate alla conservazione del nostro patrimonio culturale costruito. L’ampia diffusione delle tecniche di scansione non ci consente ancora di considerare concluso un tema di ricerca che erroneamente oggi si identifica soprattutto con la fase di “acquisizione dei dati”. Il problema è in realtà posposto alle fasi successive di elaborazione e rappresentazione e sono molti i quesiti a cui si cerca di rispondere in un tentativo di integrazione culturale tra restauro, geomatica ed elettronica: è insieme una sfida e una opportunità dove si tenta di superare le barriere linguistiche, dovute a differenti ambiti culturali, diversi approcci metodologici e vari percorsi formativi. Lo studio è condotto a livello multi-scala: a scala dell’edificio, con la Basilica di Santa Maria dell’Umiltà di Pistoia, nell’ambito della convenzione di ricerca stipulata tra il Laboratorio di Geomatica per i Beni Culturali dell’Università degli Studi di Firenze e la Soprintendenza per il Patrimonio Storico Artistico ed Etnoantropologico per le province di Firenze, Pistoia e Prato, in vista del restauro e del consolidamento dell’importante struttura rinascimentale; a scala urbana, con le Torri di San Gimignano, in occasione del progetto “RIschio Sismico negli Edifici Monumentali (RISEM)” finanziato dalla Regione Toscana e coordinato dal Dipartimento di Ingegneria Civile e Ambientale dell’Università degli Studi di Firenze, per la definizione del rischio sismico. I casi studio analizzati hanno portato alla consapevolezza che, a partire dalla banca dati tridimensionale, sempre aggiornabile e interrogabile, è possibile modulare l’elaborazione in funzione degli obiettivi interdisciplinari condivisi. Si propone, pertanto, un utilizzo nuovo della tecnica di rilievo laser scanning: l’attenzione non si pone specificatamente sugli elementi artistici e architettonici e lo scopo non è solo restituire in modalità tridimensionale un oggetto al fine di effettuare valutazioni qualitative di natura storica e culturale. L’idea è approcciarsi al dato laser con occhio critico nei confronti della struttura stessa e delle geometrie più o meno complesse. L’attenzione si sposta sugli elementi costitutivi e costruttivi, su eventuali testimonianze di fessurazioni e deformazioni critiche per l’effettiva stabilità della struttura. La necessità di disporre di un “modello irrefutabile”, a cui riferire le scelte progettuali, costituisce l’ossatura portante della ricerca. Goal of the research has been to test laser scanning acquisition, management and threedimensional representation methods and techniques to provide a valid documentation and diagnostics support aimed at the preservation of our cultural built heritage. The widespread use of scanning techniques does not allow to consider concluded yet a research topic that today is mistakenly identified especially with the phase of data acquisition. Actually the problem is postponed to the later stages of processing and representation and there are many issues partially solved through an attempt of cultural integration between restoration, geomatics and electronics: it is both a challenge and an opportunity, which carries along an effort to overcome language barriers, due to different cultural backgrounds, methodological approaches and educational paths. The study has been conducted with a multi-scale approach: at the building scale, with focus on the Basilica of Santa Maria dell’Umiltà in Pistoia, within the research agreement signed by the Laboratory of Geomatics for Cultural Heritage of the University of Florence and the Soprintendenza per il Patrimonio Storico Artistico ed Etnoantropologico per le province di Firenze, Pistoia e Prato, in view of the restoration and reinforcement of the relevant Renaissance architecture; at the urban scale, within the project “Seismic Risk in Monumental Buildings (RISEM)” funded by the Region of Tuscany and coordinated by the Department of Civil and Environmental Engineering of the University of Florence, for the seismic risk evaluation related to the San Gimignano towers. The above-mentioned case-studies raised the awareness that, on the basis of the 3D data set, which can be updated and queried at any time, it’s always possible to adjust the processing phase according to the fixed interdisciplinary goals. It is therefore proposed a new use of the laser scanning surveying technique: attention is not specifically given to the artistic and architectural elements and the aim is not only to represent an object in three-dimensions in order to make qualitative assessments on its historical and cultural value. The idea is to read data from laser scanning with the intent to review critically the structure and the more or less complex geometries. Focus is shifted on the constituent and constructive elements, on any evidence of cracks and deformations which may weaken the stability of the structure. The need for an “irrefutable model”, which can be used to orient any restoration plan, globally frames the research.

The concept of the carbon atom with four bonds extending in a tetrahedral fashion was put forward by van’t Hoff and Le Bel in 1874. It coincided with the realization that such an arrangement could be asymmetric if the four substituents were different, as shown in Figure 10.1a (van’t Hoff, 1874; Le Bel, 1874). Thus, for any compound containing one such asymmetric carbon atom, there are two isomers of opposite chirality (individually called enantiomers), for which threedimensional representations of their structural formulas are related by a mirror plane. Aqueous solutions of these enantiomers rotate the plane of polarized light in opposite directions. As discussed in Chapter 7, Pasteur showed that crystals of sodium ammonium tartrate had small asymmetrically located faces and that crystals with these so-called “hemihedral faces” rotated the plane of polarization of light clockwise, while crystals with similar faces in mirror-image positions rotated this plane of polarization counterclockwise. Thus the external form (that is, the morphology) of the crystals illustrated in Figure 10.1b was used to separate enantiomers (see Patterson and Buchanan, 1945). Pure enantiomers can only crystallize in noncentrosymmetric space groups unless both isomers are present. But even if the chemical formula and the three-dimensional structure of a molecule such as tartaric acid have been determined by standard X-ray diffraction methods, there is an ambiguity about the absolute configuration. Information about the absolute configuration is not contained in the diffraction pattern of the crystal as it is normally measured. Thus, although the substituents on the asymmetric carbon atoms have been identified, and even the detailed three-dimensional geometry of the molecule has been determined, it is not known which of the two enantiomers (mirror-image forms, analogous to those shown in Figure 10.1a) represents the three-dimensional structure of a particular individual molecule that has some distinguishing chiral property, such as the ability to rotate the plane of polarized light to the right. In other words, what is the absolute structure of the dextrorotatory form of the compound under study? A means of determining the absolute configurations of molecules was, however, provided by X-ray crystallographic studies.

"Technological advances within educational domains permit new teaching systems to emerge. Video-mapping is a technique that involves projecting images on threedimensional surfaces through motion effects. In the case of architectural projects, there are very few uses of videomapping that focus on urban planning and even fewer when the mapping is interactive. However, it is crucial to scale new ways of interpreting design using technologies such as video-mapping. In this research work, the themes of virtual environments, spatial representation, and basic design are combined with video-mapping. Students from the Digital Art and Architecture and the Industrial Design programs worked together in this effort, creating an architectural model made with 3D impressions; the users interacted and selected from the options of colors and textures available for the model city, generating different presentations according to the changes in the settings of the video-mapping software. Thus, this project opened the doors to welcome digital artists into the world of architecture and urbanism."

Processing point clouds using neural network models is a relatively new approach. The first significant works in this direction date back to 2017. Point clouds are a set of vertices in threedimensional space and characterize the external surface of an object. Due to the peculiarities of such data, typical fully connected convolutional networks cannot be applied. This is due to the fact that such data should take into account not only the color component but also the entire geometric shape of the object. This paper presents a neural network model for semantic segmentation of point clouds, which are remote sensing data of the earth. The proposed model is a modification of the original DGCNN model, which is based on the graph representation of point clouds, and atrous convolution layers were used to improve the result. The training and testing of the model was carried out on the Hessigheim 3D dataset, which was obtained by scanning a suburban area. As a result of numerical experiments on model development and data set preprocessing, acceptable results were obtained for the F1 and overall accuracy metrics.

Two historic waste packages on the Sellafield Site with potentially high fissile content were destined for re-packaging. Prior to relocation and subsequent breakdown, each item underwent a campaign of non-destructive assay. The aim of the assay was to gather information that would assist with the production of a safety case. The assay work consisted of: conventional x-ray radiography to determine the identity of the contents; gamma imaging and three-dimensional tomographic re-construction to determine the location of the gamma emitting material; and neutron coincidence counting coupled with gamma spectrometry to assign a fissile mass. Most items on the Sellafield Site that undergo non-destructive assay normally remain intact or are re-packaged with minimal interference of the content. However, in this instance each item was dismantled and the fissile material recovered. This paper provides a comparison of the measured results with the actual results for each technique. The x-ray radiographic information was used to construct a three dimensional representation of the contents of each item. This information was useful in identifying the plant items contained within. The results were discussed with plant operators who were familiar with the historic plant. The operators were able to identify areas of likely accumulations of fissile material. The two-dimensional gamma survey and subsequent threedimensional re-construction revealed the location of the gamma emitting materials within the packages. It was assumed that areas of increased gamma activity indicated areas of increased fissile mass. The neutron coincidence counting, gamma measurements and subsequent modelling provided an estimate of fissile mass for each item. The fissile mass estimate is an essential component of the safety case planning. However, it does not provide all of the information required to plan an ALARP breakdown strategy. The combination of the information gathered through assay was essential to construct a safety case that considered: transport requirements; criticality risk; dose to operator and breakdown methodology. Subsequent studies suggest that improved combination of the data acquired from the assay programme and more post-assay discussion of the specific issues and implications between the various stakeholder groups (e.g. assay engineers and safety case authors) may have led to a fissile mass result with lower uncertainties, which given a more favourable example would have resulted in a significant cost savings through reduced criticality assessment burden and mitigation actions and reduced security control.

Abstract A novel technique for three-dimensional structural and elemental analyses using a dedicated focused ion beam (FIB) and scanning transmission electron microscope (STEM) has been developed. The system employs an FIB-STEM compatible sample holder with sample stage rotation mechanism. A piece of sample (micro sample) is extracted from the area to be characterized by the micro-sampling technique [1-3]. The micro sample is then transferred onto the tip of the stage (needle stage) and bonded by FIB assisted metal deposition. STEM observation of the micro sample is carried out after trimming the sample into a micro-pillar 2-5 micron squared in cross-section and 10 -15 micron in length (micro-pillar sample). High angle annular dark field (HAADF) STEM, bright field STEM and secondary electron microscopy (SEM) images are obtained at 200kV resulting in threedimensional and cross sectional representations of the microsample. The geometry of the sample and the needle stage allows observation of the sample from all directions. The specific site can be located for further FIB milling whenever it is required. Since the operator can choose materials for the needle stage, the geometry of the original specimen is not a limiting factor for quantitative energy dispersive X-ray (EDX) analysis.