Διπλωματικές Εργασίες

Μόνιμο URI για αυτήν τη συλλογήhttps://dspace.library.tuc.gr/handle/123456789/118

Νέα

Περιηγούμαι

Τώρα δείχνει 1 - 20 από 125

3D photorealistic reconstruction and digital restoration of Neoria, Crete using geodetic measurement and computer graphics techniques
(Technical University of Crete, 2015) Sarri Effrosyni; Σαρρη Ευφροσυνη; Mania Aikaterini; Μανια Αικατερινη; Ragia Lemonia; Ραγια Λεμονια; Christodoulakis Stavros; Χριστοδουλακης Σταυρος
This thesis puts forward a 3D reconstruction methodology applied to a historic building taking advantage of the combined speed, range and accuracy of a total geodetic station. The measurements representing geographical data, produced an accurate and photorealistic geometric mesh of a historic monument named ‘Neoria’. ‘Neoria’ is a Venetian building located by the old harbour at Chania, Crete, Greece. The integration of tacheometry acquisition and computer graphics puts forward an effective framework for the accurate 3D reconstruction of a historical building. The main technical challenge of this work was the production of an accurate 3D mesh based on a sufficient but small number of tacheometry measurements acquired fast and at low-cost. A combination of surface reconstruction and processing methods ensured that a detailed geometric mesh was constructed based on a few points. A fully interactive application based on game engine technologies was developed in regards to the reconstructed monument. The user can visualize and tour the monument and the area around it, as well as manipulating the model. Advanced interactive functionalities are offered to the user in relation to identifying restoration areas and visualizing the outcome of such works. Moreover, the user could visualize the co-ordinates of the points measured, calculate distances at will and navigate the complete 3D mesh of the monument. The goal of this framework is to utilize a small number of acquired data points and present a fully interactive visualization of a georeferenced 3D model.
Automated brain structures segmentation using the mean-shift algorithm
(Πολυτεχνείο Κρήτης, 2010) Μαυριγιαννάκης Κωνσταντίνος
Μη διαθέσιμο
Biochemical analysis on Lab on a Chip
(Technical University of Crete, 2014) Kobotheklas Konstantinos; Κομποθεκλας Κωνσταντινος; Kalaitzakis Kostas; Καλαϊτζακης Κωστας; Balas Costas; Μπαλας Κωστας; Koutroulis Eftychios; Κουτρουλης Ευτυχιος
Emerging issues, modern design trends and future challenges for system design research and design of System-on-a-Chip (SoC), are the focus of semiconductor industry. The architecture of SoC designers consider the overall system performance variably (power, thermal efficiency, production costs, etc. ) in order to present to the market complex and competitive products. With the help of micro-fluidic remarkable is the progress in development of Lab-on-a-Chip (LoC) systems in various fields such as the study of cell biology and disease diagnosis. The micro- biosensors, which are based on LoC systems can incorporate numerous techniques for analysis of biochemical reactions, including analysis based on the image, and techniques for the analysis of genes and proteins of the cell. Medical devices that are already on the market provide significant clinical credibility through immunological tests and Point-of-Care (POC) tests for clinical chemistry. Future applications include complex tests, POC tests with high sensitivity and rather complicated tests, such as nucleic acid tests or the integration of multiple tests in one.
Cache management policies for streaming proxies : the cases of fixed and variable video sizes and collaboration among proxies
(Πολυτεχνείο Κρήτης, 2015) Kyriazis Athanasios; Κυριαζης Αθανασιος; Paterakis Michalis; Πατερακης Μιχαλης; Koutsakis Polychronis; Κουτσακης Πολυχρονης; Bletsas Aggelos; Μπλετσας Αγγελος
The easy access on the Internet, the exponential growth of the Internet traffic and the ever enlarging sizes of files which are transferred over it, often lead to network congestion and significant delays in many applications that require timely data transfer. The most important part of data transfer over the Internet corresponds to media streaming applications which require a large portion of the available bandwidth, while at the same time there is the need of achieving low delays, because the delays in these applications are very annoying to the users and some of them may not be willing to experience them. In order to improve the services provided to the users of these applications, the techniques of video caching and of collaborative caching are used. Video caching embodies proxy servers on the network in order to keep frequently accessed data at locations close to the clients. Collaborative caching uses group of proxies which can collaborate with each other, and achieve better performance than with independent standalone proxies. This Thesis proposes new efficient algorithms for video caching which manage the cache of the proxy servers for video transfer in real time and compares them to existing algorithms. Also, a new effective collaborative scenario is proposed and evaluated. In the first two parts of the Thesis the performance of three existing efficient algorithms in the literature, the Number of Common Clients - Size (NCCS), the Least Recently and Least Frequently Used (LRLFU) and the Least Recently Used (LRU) is evaluated and compared for the cases of fixed and variable video sizes. In each of the first two parts of the Thesis a new cache management algorithm is also designed and proposed, this new algorithm consists of a combination of existing efficient algorithms. In the first part of the Thesis the proposed new algorithm (referred to as the LRLFU_Aggressive) does not perform much better than the existing algorithms, but in the second part the proposed new algorithm (referred to as the LRLFU_Modified) significantly improves the performance of the system in comparison to the existing algorithms. In the cache replacement algorithms we examine a value defined for each video, namely the caching value, which is based on the popularity of the videos, in order to retain in the cache the most popular videos. For each requested video which does not exist into the cache, other videos have to be removed (the ones with the lower caching values) in order for the new video to be cached. The performance metrics we use to evaluate and compare the algorithms in our system are the Video Hit Ratio and the Fraction of the Delayed Starts. In the third part of the Thesis a collaborative scheme of two client communities each associated with one proxy server, is defined and studied. While most of the studies in the area of collaborative proxies use the same cache management algorithm in each proxy and assume that each client community communicates via the corresponding proxy with the same content server, in our collaborative system we have used a different cache management algorithm in each of the two proxies and we assumed that there are two content servers each one associated with one of the client communities. Furthermore, we assumed that each of the client communities communicates via the corresponding proxy only with its corresponding content server. Also, we assumed that there is an overlap between the contents of the two content servers. Each of the two different cache management algorithms used in the collaborative scheme caches different videos in the corresponding proxy, and this helps the overall system performance. From the results of our simulation study we derive important conclusions for the performance of the examined collaborative scheme.
Combining voice and touch modalities in educational games for preschoolers
(Πολυτεχνείο Κρήτης, 2015) Giannakouras Panagiotis; Γιαννακουρας Παναγιωτης; Mania Aikaterini; Μανια Αικατερινη; Digalakis Vasilis; Διγαλακης Βασιλης; Potamianos Alexandros; Ποταμιανος Αλεξανδρος
Η ραγδαία πρόοδος και εξέλιξη σε όλους τους τομείς της τεχνολογίας στις μέρες μας, κάνει πιο προσιτή την επαφή των ανθρώπων με τους ηλεκτρονικούς υπολογιστές σε όλο και νεαρότερες ηλικίες. Παράλληλα, η πρόοδος της ανάπτυξης λογισμικού με τη μορφή διάφορων εφαρμογών σε επίπεδο υπολογιστή ή ταμπλέτας διευκολύνει πολλές πτυχές της καθημερινότητάς μας και βελτιώνει τον τρόπο και την ποιότητα της ζωής μας. Οι εφαρμογές και ιδιαίτερα αυτές που συνδυάζουν φωνή και αφή (διαδραστικότητα με το χρήστη), έχουν αποδειχθεί ιδιαίτερα ευεργετικά για παιδιά κάθε ηλικίας από προσχολική μέχρι και έφηβους. Στην εργασία αυτή, αρχικά, γίνεται μια σύντομη αναφορά στο θεωρητικό πλαίσιο που βασίζεται η εργασία και σε κάποιες συγκεκριμένες θεωρίες μάθησης (πχ. Piaget). Το κύριο μέρος της διπλωματικής εργασίας αφορά την υλοποίηση ενός σεναρίου για την εκμάθηση απλών ακολουθιών ενεργειών σε παιδία προσχολικής ηλικίας, με τη βοήθεια της εφαρμογής που αναπτύχθηκε σε γραφικό περιβάλλον flash, με τον πιο ευχάριστο και δημιουργικό τρόπο. Το περιβάλλον που δημιουργήθηκε είναι κατάλληλο για τη συγκεκριμένη εφαρμογή, διότι είναι ανθρωπόμορφη και εύκολη να αλληλεπιδράσει με παιδιά μικρής ηλικίας. Το παιδί λοιπόν, θα πρέπει να φέρει σε πέρας ένα σύνολο δοκιμασιών με τη βοήθεια κάποιων συμβουλών που του δίνονται και κάποιων οδηγιών αλλά και κάποιων επιπλέον εξαρτημάτων που θα χρησιμοποιήσουμε, επιτυγχάνοντας κάθε φορά και ένα σκοπό μέχρι να ολοκληρώσει την αποστολή. Έτσι, αλληλεπιδρώντας το παιδί με το γραφικό περιβάλλον, εξοικειώνεται με τη διαδικασία επίλυσης προβλημάτων, ενώ παράλληλα γνωρίζει τα βασικά στοιχεία ενός διαδραστικού συστήματος, μαθαίνοντας να χειρίζεται εργαλεία αναγνώρισης φωνής και αφής.
Community RF sensing
(Πολυτεχνείο Κρήτης, 2012) Alimpertis Emmanouil; Αλιμπερτης Εμμανουηλ; Bletsas Aggelos; Μπλετσας Αγγελος; Garofalakis Minos; Γαροφαλακης Μινως; Lagoudakis Michael; Λαγουδακης Μιχαηλ
Data classification and mapping in optical dynamic contrast-enhanced imaging of cervical neoplasia.
(Technical University of Crete, 2014) Chiou Eleni; Χιου Ελενη; Balas Costas; Μπαλας Κωστας; Zervakis Michalis; Ζερβακης Μιχαλης; Lagoudakis Michael; Λαγουδακης Μιχαηλ
Decomposition methods for network utility maximization
(Πολυτεχνείο Κρήτης, 2015) Kostoulas Georgios; Κωστουλας Γεωργιος; Liavas Athanasios; Λιαβας Αθανασιος; Paterakis Michalis; Πατερακης Μιχαλης; Koutsakis Polychronis; Κουτσακης Πολυχρονης
Network Utility Maximization (NUM) is the problem of allocating the right amount of resources to the nodes of a network, in order to maximize an overall utility function. There are many optimization tools to solve this problem in a centralized manner. In this thesis, we discuss distributed ways to solve various formulations of NUM problems. We decompose the problems into subproblems using Primal Decomposition, by applying direct resource allocation and then adjust the resources by small steps until equilibrium, and Dual Decomposition by pricing the resource in such manner that each node achieves the optimal utility. Many alternatives can be derived from these two methods, in different NUM formulations, with the use of multilevel decompositions. These decompositions may lead to better understanding of existing networks, reverse engineering of network protocols like TCP, better management of existing networks, and ways to design and operate new networks by layering as optimization. Finally, we experiment with the message passing of these algorithms and try to minimize the data transferred by quantizing the values.
Design and implementation of a platform for the development and management of learning experiences in location-based mobile games
(Πολυτεχνείο Κρήτης, 2015) Makris Dimitrios-Ioannis; Μακρης Δημητριος-Ιωαννης; Christodoulakis Stavros; Χριστοδουλακης Σταυρος; Deligiannakis Antonios; Δεληγιαννακης Αντωνιος; Lagoudakis Michael; Λαγουδακης Μιχαηλ
Recent international surveys present that educational games can be used to promote critical thinking and enhance problem solving skills even in the early school ages. On the other hand, it is a common belief that due to the rapidly changing technology, education should be adapted in order to follow the changes and the new needs of students. To this end, any tool supporting the creation of educational learning experiences, through the use of modern devices and technologies, is considered invaluable both for educators and young learners. In this thesis we discuss the design and implementation of a platform for the development and management of learning experiences in location-based games. More specifically, we present an authoring tool (desktop application) supporting the creation and management of mobile location-based games, as well as scenario editing, user interface customization and organization of gaming activities. Furthermore, we present the player application (mobile application) that we have developed, supporting the play of games which have been created using the authoring tool. The player application is compatible with most state-of-the-art mobile devices and platforms, while both tools have been designed with flexibility and extensibility in mind. To this end, they can be used in various domains including education, museum exploration, city sightseeing, as well as in everyday gaming activities for having fun. Our applications are compatible with well known modern educational tools and repositories through the direct use of the Tin Can API. Finally, is worth mentioning that they have been evaluated for their usability by professionals and naive users.
Design and implementation of the OpenMP 4.0 task dataflow model for cache-coherent shared-memory parallel systems in the runtime of the OMPi OpenMP/C compiler
(Πολυτεχνείο Κρήτης, 2015) Souris Anastasios; Σουρης Αναστασιος; Pnevmatikatos Dionysios; Πνευματικατος Διονυσιος; Deligiannakis Antonios; Δεληγιαννακης Αντωνιος
Development of a 3D game for mobile platforms with autonomous interactive characters
(Technical University of Crete, 2014) Verykokidi Eleni-Aggela; Βερυκοκιδη Ελενη-Αγγελα; Mania Aikaterini; Μανια Αικατερινη; Lagoudakis Michael; Λαγουδακης Μιχαηλ; Deligiannakis Antonios; Δεληγιαννακης Αντωνιος
Η διπλωματική εργασία αφορά την δημιουργία ενός τρισδιάστατου παιχνιδιού για κινητές συσκευές αφής με την πλατφόρμα Unity3D. Η εφαρμογή υποστηρίζεται από το λειτουργικό συστήμα Android μέσω των Android Development Tools και Android SDK. Το παιχνίδι υλοποιήθηκε σε γλώσσα UnityScript (JavaScript). Αξιοποιήθηκαν οι δυνατότητες που προσφέρουν οι κινητές συσκευές, όπως είναι το επιταχυνσιόμετρο, το γυροσκόπιο και οι αισθητήρες αφής, μέσα από τη διαχείριση του παιχνιδιού και την κίνηση του ήρωα. Ο ήρωας είναι ένας πιγκουίνος, ο οποίος σχεδιάστηκε με το πρόγραμμα μοντελοποίησης Maya. Στους χαρακτήρες του παιχνιδιού έχει προστεθεί τεχνητή νοημοσύνη για να αλληλεπιδρούν με τον ήρωα και να βρίσκουν την συντομότερη διαδρομή προς το στόχο τους. Οι εχθροί τον εντοπίζουν στον χώρο, τον κυνηγούν και του επιτίθονται, ενώ ο σύμμαχος του δείχνει το δρόμο προς το σημείο τερματισμού όσο ο ήρωας τον πλησιάζει. Είναι ένα ολοκληρωμένο παιχνίδι, κατηγορίας Action, Adventure και Arcade, έτοιμο για χρήση. Υποστηρίζεται από πολλές διαφορετικές συσκευές, είναι κατάλληλα σχεδιασμένο για μικρές οθόνες και προσαρμόζεται στα διάφορα μεγέθη οθονών.
Development of a computer controlled tunable wavelength light source from ultraviolet to infrared
(Πολυτεχνείο Κρήτης, 2013) Rossos Christos; Ρωσσος Χρηστος; Balas Costas; Μπαλας Κωστας; Kalaitzakis Kostas; Καλαϊτζακης Κωστας; Pnevmatikatos Dionysios; Πνευματικατος Διονυσιος
Development of a self-screening/training mobile platform for eye pathologies
(Technical University of Crete, 2014) Gatzos Evaggelos; Γκατζος Ευαγγελος; Balas Costas; Μπαλας Κωστας; Lagoudakis Michael; Λαγουδακης Μιχαηλ; Mania Aikaterini; Μανια Αικατερινη
Development of an advanced platform for controlling the imaging parameters of CMOS image sensors.
(Πολυτεχνείο Κρήτης, 2014) Trilyraki Aikaterini; Τριλυρακη Αικατερινη; Balas Costas; Μπαλας Κωστας; Papaefstathiou Ioannis; Παπαευσταθιου Ιωαννης; Bucher Matthias; Bucher Matthias
Development of an autofocusing system for digital cameras
(Technical University of Crete, 2014) Koutlis Vasileios; Κουτλης Βασιλειος; Balas Costas; Μπαλας Κωστας; Lagoudakis Michael; Λαγουδακης Μιχαηλ; Kalaitzakis Kostas; Καλαϊτζακης Κωστας
Η συγκεκριμένη διπλωματική εργασία μελετάει την ανάπτυξη ενός συστήματος αυτόματης εστίασης, δηλαδή ενός συστήματος που θα εστιάζει πλήρως σε ένα αντικείμενο και θα έχει την βέλτιστη απόκριση. Πριν την ενασχόλησή μας με το θεωρητικό και λογισμικό σκέλος καθορίσαμε τα στοιχεία αυτά που μας είναι απαραίτητα για τη δημιουργία της πειραματικής διάταξης. Όσο αφορά το λογισμικό, για να επιτύχουμε την ανάπτυξη ενός τέτοιου συστήματος εξετάσαμε διαφορετικούς αλγορίθμους και συναρτήσεις. Για να επιτύχουμε τη βέλτιστη εικόνα βασιστήκαμε στην τιμή-εστίασης (focus value), η οποία είναι μία μεταβλητή που υπολογίζει το πόσο καλά εστιασμένη είναι η εικόνα. Για να μετρηθεί αυτή η μεταβλητή χρησιμοποιήσαμε τέσσερις διαφορετικές συναρτήσεις, οι οποίες και αναλύονται με τη χρήση γραφημάτων στα πλαίσια αυτής της διπλωματικής. Αναπόφευκτα, στη μέτρηση αυτής της τιμής εισάγεται σφάλμα, το οποίο ελαχιστοποιούμε με τη χρήση φίλτρων κατά τη διάρκεια λήψης της εικόνας, και μέσω ελέγχου της φωτεινότητας. Η εφαρμογή του συστήματος έγινε κάτω από ποικίλες περιπτώσεις έντασης του φωτός με πολύ ικανοποιητικά αποτελέσματα.
Development of breast cancer surgery magnetic navigation system
(Technical University of Crete, 2013) Tsoulidis Nikolaos; Τσουλιδης Νικολαος; Balas Costas; Μπαλας Κωστας; Kalaitzakis Kostas; Καλαϊτζακης Κωστας
Development of underwater vision improving system
(Technical University of Crete, 2015) Petridis Nikolaos; Πετριδης Νικολαος; Balas Costas; Μπαλας Κωστας; Samoladas Vasilis; Σαμολαδας Βασιλης; Stavrakakis Georgios; Σταυρακακης Γεωργιος
Underwater imaging is important for scientiﬁc research and technology, as well as for popular activities. This paper describes a method to overcome limitations in underwater imaging using colour correction and polarizing filters. Scattering and colour absorption are two major problems of distortion for imaging, especially in underwater environment. Scattering is caused by large suspended particles, like fog or turbid water. Colour degradation corresponds to the varying degrees of attenuation encountered by light travelling in the water with different wavelengths, rendering ambient underwater environments dominated by a bluish tone. Our key target was to create a simple and cost efficient method eliminating satisfactorily image blurring and increase colour intensity and visual acuity in natural an artificial lighting source. We demonstrated light as a signal with scattering and backscattering distorting images and also analyzed the function of the human eye contributing to the constraints of vision especially in underwater environment. We researched various different approaches encounter the same topic and made a comparative study and developed an underwater vision system which improves contrast and visual image quality and explained the physical effects of visibility degradation.
Discriminative training of language models
(Technical University of Crete, 2014) Fytopoulos Nikolaos; Φυτοπουλος Νικολαος; Digalakis Vasilis; Διγαλακης Βασιλης; Lagoudakis Michael; Λαγουδακης Μιχαηλ; Diakoloukas Vasilis; Διακολουκας Βασιλeioς
The present thesis investigates the use of discriminative training on continuous Language Models. The main motivation for dealing with continuous language models was that by construction they overcome the limits of N-gram based models. N-gram models have been widely used in Language Modeling, but suffer from lack of generalizability and contain a very large number of parameters that are hard to adapt. Another flaw of N-gram models is the need for a large amount of training data, in order to cover as many N-grams as possible. Continuous Gaussian Mixture Language Models (GMLMs) for Speech Recognition have proven to be effective in terms of smoothing unseen events and adapting efficiently while using relatively small amount of data when compared to N-gram models. The training and testing data were extracted from the Wall Street Journal Corpus. Although the size of the vocabulary used in the corpus is large, the actual number of words being used in the present thesis is resticted. Data has the form of a continuous-space vector and consists of the history of each word in the corpus. The dimensions of these vectors were reduced by using SVD and LDA techniques. As far as the main objective of the thesis is concerned, attempts focus on improving the performance of GMLMs that have been previously trained by using the ML criterion on Language Models by adapting and using the Maximum Mutual Information(MMI) Estimation Method previously deployed in training HMMs for acoustic models. MMI acoustic models have proven to perform better than ML models, therefore MMI training gave a strong incentive in order to apply it on continuous language models. In addition, other discriminative criteria such as Minimum Phone Error (MPE) or Minimum Classification Error(MCE) are also theoretically investigated. Perplexity is the metric being used to measure the effectiveness of the presented method. The experiments of the thesis focus on testing MMI models that are smoothed with their correspondent baseline ML model and MMI models that are unsmoothed, with mixed results. The desired improvement is achieved in the case of unsmoothed MMI models against ML models.
Distributed convex optimization using ADMM
(Πολυτεχνείο Κρήτης, 2014) Christodouleas Dimitrios; Χριστοδουλεας Δημητριος; Liavas Athanasios; Λιαβας Αθανασιος; Garofalakis Minos; Γαροφαλακης Μινως; Digalakis Vasilis; Διγαλακης Βασιλης
Lately, in engineering it has been necessary to develop algorithms that handle “big data” optimization problems in a distributed manner. In this thesis, we present ADMM (Alternating Direction Method of Multipliers) algorithm, as the basic tool for solving these kinds of problems, and its application in machine learning and signal processing problems.
Distributed event detection using the Storm System
(Πολυτεχνείο Κρήτης, 2014) Manikaki Vasiliki; Μανικακη Βασιλικη; Deligiannakis Antonios; Δεληγιαννακης Αντωνιος; Garofalakis Minos; Γαροφαλακης Μινως; Samoladas Vasilis; Σαμολαδας Βασιλης
Distributed event detection is the process of identifying specific occurrences of interest in incoming data available at a number of distributed nodes. The traditional approach for detecting events implies central collection and processing of data, which is impractical for a number of reasons. Firstly, since the number of nodes might be large, collecting information centrally is not always possible or efficient. This happens because the amount of information to be transmitted may be huge and the available bandwidth insufficient to accommodate the transmission. Secondly, in some networks such as sensor networks, transmitting information draws additional power, which is not desirable because usually the sensors have limited battery power and their power source may be irreplaceable. Subsequently, it is not recommended to send all available information to a central node because this transmission will consume a substantial amount of power. For these reasons, one of the most significant limitations of sensor networks is the need to reduce energy consumption. The geometric method was proposed relatively recently and allows a network to monitor in a distributed way if the value of a complex function, even nonlinear, calculated using incoming data is over or under a specific threshold value. Thus, composite events can be distributely detected if they are expressed as a threshold monitoring function. The geometric method imposes a set of local constraints on each node and manages to reduce the need for communication between the nodes as long as the constraints are satisfied. In this work, the geometric method is implemented, using the real-time distributed computation framework named Storm, for distributed event detection. A topology implementing the geometric method has been constructed using the components provided by the Storm framework, allowing scalable processing of data acquired from nodes and monitoring of certain functions. Finally, the system also allows runtime addition of new functions that can be monitored.

Περιηγούμαι

Πλοήγηση Διπλωματικές Εργασίες ανά Τίτλο