Opacity of hot, highly compressed hydrogen Final report

Ballistic piston compressor used to study opacity of hot highly compressed hydroge

Thermodynamic properties of a high pressure subcritical UF6/He gas volume (irradiated by an external source)

A computer simulation study concerning a compressed fissioning UF6 gas is presented. The compression is to be achieved by a ballistic piston compressor. Data on UF6 obtained with this compressor were incorporated in the simulation study. As a neutron source to create the fission events in the compressed gas, a fast burst reactor was considered. The conclusion is that it takes a neutron flux in excess of 10 to the 15th power n/sec sq cm to produce measurable increases in pressure and temperature, while a flux in excess of 10 to 19th power n/sq cm sec would probably damage the compressor

Substance deposition assessment in obstructed pulmonary system through numerical characterization of airflow and inhaled particles attributes

Background Chronic obstructive pulmonary disease (COPD) and asthma are considered as the two most widespread obstructive lung diseases, whereas they affect more than 500 million people worldwide. Unfortunately, the requirement for detailed geometric models of the lungs in combination with the increased computational resources needed for the simulation of the breathing did not allow great progress to be made in the past for the better understanding of inflammatory diseases of the airways through detailed modelling approaches. In this context, computational fluid dynamics (CFD) simulations accompanied by fluid particle tracing (FPT) analysis of the inhaled ambient particles are deemed critical for lung function assessment. Also they enable the understanding of particle depositions on the airways of patients, since these accumulations may affect or lead to inflammations. In this direction, the current study conducts an initial investigation for the better comprehension of particle deposition within the lungs. More specifically, accurate models of the airways obstructions that relate to pulmonary disease are developed and a thorough assessment of the airflow behavior together with identification of the effects of inhaled particle properties, such as size and density, is conducted. Our approach presents a first step towards an effective personalization of pulmonary treatment in regards to the geometric characteristics of the lungs and the in depth understanding of airflows within the airways. Methods A geometry processing technique involving contraction algorithms is established and used to employ the different respiratory arrangements associated with lung related diseases that exhibit airways obstructions. Apart from the normal lung case, two categories of obstructed cases are examined, i.e. models with obstructions in both lungs and models with narrowings in the right lung only. Precise assumptions regarding airflow and deposition fraction (DF) over various sections of the lungs are drawn by simulating these distinct incidents through the finite volume method (FVM) and particularly the CFD and FPT algorithms. Moreover, a detailed parametric analysis clarifies the effects of the particles size and density in terms of regional deposition upon several parts of the pulmonary system. In this manner, the deposition pattern of various substances can be assessed. Results For the specific case of the unobstructed lung model most particles are detected on the right lung (48.56% of total, when the air flowrate is 12.6 L/min), a fact that is also true when obstructions arise symmetrically in both lungs (51.45% of total, when the air flowrate is 6.06 L/min and obstructions occur after the second generation). In contrast, when narrowings are developed on the right lung only, most particles are pushed on the left section (68.22% of total, when the air flowrate is 11.2 L/min) indicating that inhaled medication is generally deposited away from the areas of inflammation. This observation is useful when designing medical treatment of lung diseases. Furthermore, particles with diameters from 1 μm to 10 μm are shown to be mainly deposited on the lower airways, whereas particles with diameters of 20 μm and 30 μm are mostly accumulated in the upper airways. As a result, the current analysis indicates increased DF levels in the upper airways when the particle diameter is enlarged. Additionally, when the particles density increases from 1000 Kg/m3 to 2000 Kg/m3, the DF is enhanced on every generation and for all cases investigated herein. The results obtained by our simulations provide an accurate and quantitative estimation of all important parameters involved in lung modeling. Conclusions The treatment of respiratory diseases with inhaled medical substances can be advanced by the clinical use of accurate CFD and FPT simulations and specifically by evaluating the deposition of inhaled particles in a regional oriented perspective in regards to different particle sizes and particle densities. Since a drug with specific characteristics (i.e. particle size and density) exhibits maximum deposition on particular lung areas, the current study provides initial indications to a qualified physician for proper selection of medication

Techniques for reliable surveillance systems

169 σ.Τα συστήματα παρακολούθησης έχουν σημαντικό ρόλο στις εφαρμογές ανίχνευσης συμβάντων και ανάλυσης. Ωστόσο, οι τεχνικές παρακολούθησης αντικειμένων εξακολουθούν να είναι μία από τις μεγαλύτερες προκλήσεις στον τομέα της όρασης υπολογιστών, παρόλο που έχουν μελετηθεί εκτενώς κατά τη διάρκεια των προηγούμενων ετών. Στην παρούσα διατριβή, παρουσιάζεται η ροή αντικείμενου, η οποία χρησιμοποιείται για την εκτίμηση της μετατόπισης και της κατεύθυνσης ενός συγκεκριμένου αντικειμένου. Σε σύγκριση με τις τεχνικές ανίχνευσης και παρακολούθησης, η προτεινόμενη προσέγγιση μπορεί να υπολογίσει την κατεύθυνση του αντικειμένου με απευθείας τρόπο, ενώ παράλληλα μπορεί να αγνοεί άλλες άσχετες κινήσεις μέσα στην σκηνή. Ως εκ τούτου, η ροή αντικείμενου έχει τη δυνατότητα να εστιάζει συνεχώς σε ένα συγκεκριμένο αντικείμενο και να υπολογίζει το πεδίο της κίνησης του. Επίσης, η ροή αντικείμενου ενσωματώνεται σε μία αξιόπιστη προσέγγιση παρακολούθησης, η οποία χρησιμοποιεί ένα παραγωγικό prior, με στόχο να αντιμετωπίσει τις αλλαγές της εμφάνισης ενός αντικειμένου. Επιπλέον, προτείνεται ένας μηχανισμός επαλήθευσης δείγματος πραγματικού χρόνου. Η αποτελεσματικότητα της προτεινόμενης μεθόδου παρουσιάζεται σε ποικίλες ακολουθίες, όπως σε ένα σύνθετο βιομηχανικό περιβάλλον. Τα πειραματικά αποτελέσματα δείχνουν ότι η προτεινόμενη τεχνική είναι αξιόπιστη και έχει καλύτερη απόδοση από άλλες μοντέρνες τεχνικές παρακολούθησης αντικειμένων.Camera based supervision is a critical part of event detection and analysis applications. However, visual tracking still remains one of the biggest challenges in the area of computer vision, although it has been extensively discussed during in the previous years. In this thesis, object flow is introduced, for estimating both the displacement and the direction of an object-of-interest. Compared to the detection and tracking techniques, the proposed approach obtains the object displacement directly, while ignoring other irrelevant movements in the scene. Hence, object flow has the ability to continuously focus on a specific object and calculate its motion field. A robust tracking approach based on object flow and an observation model that utilizes a generative prior are adopted to tackle the pitfalls that derive from the appearance changes of the object-of-interest. In addition, an on-line sample verification mechanism is proposed. The efficiency of the proposed technique is demonstrated on various sequences, such as a complex industrial environment. The experimental results show that the proposed technique is sound, yielding improved performance in comparison with other tracking approaches.Κωνσταντίνος Γ. Λάλο

A Cross Media Platform for Personalized Leisure & Entertainment: The POLYMNIA Approach

The POLYMNIA project aims to develop an intelligent cross-media platform for personalised leisure and entertainment in thematic parks or venues. The system allows the visitors to be the real protagonist in the venue. Towards this goal, POLYMNIA platform is equipped with innovative imaging technologies for real time detection, localisation and tracking of “human content”, i.e., the human visitor within the recoding being made in real-time by the system. No constraints are imposed on the variation of the environment. New, content-based media representation and organisation schemes will be developed to provide scalable, efficient and user-oriented description of the “human content”, enabling efficient retrieval, access, and delivery across heterogeneous media platforms. In addition, adaptive mechanisms are employed to update the system response to the current users’ information needs and preferences