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Evaluation of Idempotency & Block Size of Data on the Performance of Normalized Compression Distance AlgorithmMandhapati, Venkata Srikanth, Bajwa, Kamran Ali January 2012 (has links)
Normalized compression distance (NCD) is a similarity distance metric algorithm which is used for the purpose of analyzing the type of file fragments. The performance of NCD depends upon underlying compression algorithm to be used. We have studied three compressors bzip2, gzip and ppmd, the compression ratio of ppmd is better than bzip2 and the compression ratio of bzip2 is better than gzip, but which one out of these three is better than one another in the viewpoint of idempotency is evaluated by us. Then we have applied NCD along with k nearest neighbour as a classification algorithm to a randomly selected public corpus data with different block sizes (512 byte, 1024 bytes, 1536 bytes, 2048 bytes). The performance of two compressors bzip2 and gzip is also compared for the NCD algorithm in the perspective of idempotency. Objectives: In this study we have investigated the In this study we have investigated the combine effect of both of the parameters namely compression ratio versus idempotency and varying block size of data on the performance of NCD. The objective is to figure out that in order to have a better performance of NCD either a compressor for NCD should be selected on the basis of better compression ratio of compressors or better idempotency of compressors. The whole purpose of using different block sizes was to evaluate either the performance of NCD will improve or not by varying the block size of data to be used for making the datasets. Methods: Experiments are performed to test the hypotheses and evaluate the effect of compression ratio versus idempotency and block size of data on the performance of NCD. Results: The results obtained after the analysis of null hypotheses of main experiment are retained, which showed that there is no statistically significant difference on the performance of NCD when varying block size of data is used and also there is no statistically significant difference on the NCD’s performance when a compressor is selected for NCD on the basis of better compression ratio or better idempotency. Conclusions: As the results obtained from the experiments are unable to reject the null hypotheses of main experiment so no conclusion could be drawn of the effect of the independent variables on the dependent variable i.e. there is no statistically significant effect of compression ratio versus idempotency and varying block size of data on performance of the NCD.
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Investigando as políticas de assistência e proteção à infância : psicologia e ações do Estado / Investication about the infancy assistance and protection policies in BrazilIrene Bulcão 12 March 2006 (has links)
Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro / Esta tese consiste em uma investigação bibliográfica e documental sobre as políticas de assistência e proteção à infância no Brasil. Com relação a esta questão, pesquisei fios de nossa história desde o período colonial até o final da chamada Era Vargas. Inicio este percurso histórico num momento em que o abandono de crianças não era considerado um problema, e funcionavam engrenagens de proteção por proximidade; caminho até os anos de 1930, quando médicos e juristas se mobilizam no sentido de organizar a assistência e a proteção ao menor de idade, contribuindo para a criação de outros modelos de atendimento à infância, baseados na assistência social e na proteção de Estado. Neste ponto, faço uma breve análise da chegada de Getúlio Vargas ao governo e de sua permanência nele até 1945. Em seguida discuto as mudanças ocorridas na estrutura das relações entre capital e trabalho na sociedade capitalista européia, quando o social se configurou enquanto um novo domínio de saber que possibilitou a emergência dos chamados profissionais do social, apontando similaridades com o processo ocorrido no Brasil durante a Era Vargas. A análise se foca, então, nos movimentos de criação e implementação de ações específicas para tratar da criança dita desassistida durante o Estado Novo, implementadas a partir do funcionamento de dois órgãos: o Departamento Nacional da Criança (DNCr) criado em 1940 para coordenar todas as atividades relativas a proteção à maternidade, à infância e à adolescência e o Serviço de Assistência a Menores (S.A.M.) criado em 1941 para superintender todo o serviço de amparo a menores desvalidos e delinqüentes, buscando sempre identificar que noções de psicologia que se faziam aí presentes. À guisa de conclusão, compartilho descobertas, encontros e desencontros proporcionados pela realização deste trabalho. / This thesis consists of a bibliographical and documental investigation about the infancy assistance and protection policies in Brazil. Related to this question, I researched historical lines since the colonial period up to the end of the so called Vargas Era. I start this historical course at the moment in which the children abandonment was not considered as a problem, and mechanisms worked as protection by proximity; I go back to the 1930s, when physicians and jurists mobilize themselves towards the underaged assistance and protection organization, which contributed to the creation of other attendance models, based on social assistance and on the State protection. At his point I make a concise analysis of Getúlio Vargas arrival at government and of his stay as president until 1945. Following this, I discuss the ocurred changes in the relationship structures between capital and work in the capitalist european society, when the social was configured as a new knowledge domain which allowed the emergence of the so caleed social professionals, pointing to similarities with the ocurred process in Brazil during the Vargas Era. Then, the analysis focuses itself in the creation and implementation movements of specific actions to treat the called not assisted child during the New State, implemented from the operation of two organs: the National Child Department (NCD) created in 1940 to coordinate all activities related to the protection of motherhood, infancy and adolescence and the Underaged Assistance Servic (UAS) created in 1941 to superintend all the services to assist unprotected underaged and delinquents , always searching to identify which psychology conceptions were present in both of them. As Conclusion, I share the foundings, encounters and discordances allowed by the realization of this work.
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Investigando as políticas de assistência e proteção à infância : psicologia e ações do Estado / Investication about the infancy assistance and protection policies in BrazilIrene Bulcão 12 March 2006 (has links)
Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro / Esta tese consiste em uma investigação bibliográfica e documental sobre as políticas de assistência e proteção à infância no Brasil. Com relação a esta questão, pesquisei fios de nossa história desde o período colonial até o final da chamada Era Vargas. Inicio este percurso histórico num momento em que o abandono de crianças não era considerado um problema, e funcionavam engrenagens de proteção por proximidade; caminho até os anos de 1930, quando médicos e juristas se mobilizam no sentido de organizar a assistência e a proteção ao menor de idade, contribuindo para a criação de outros modelos de atendimento à infância, baseados na assistência social e na proteção de Estado. Neste ponto, faço uma breve análise da chegada de Getúlio Vargas ao governo e de sua permanência nele até 1945. Em seguida discuto as mudanças ocorridas na estrutura das relações entre capital e trabalho na sociedade capitalista européia, quando o social se configurou enquanto um novo domínio de saber que possibilitou a emergência dos chamados profissionais do social, apontando similaridades com o processo ocorrido no Brasil durante a Era Vargas. A análise se foca, então, nos movimentos de criação e implementação de ações específicas para tratar da criança dita desassistida durante o Estado Novo, implementadas a partir do funcionamento de dois órgãos: o Departamento Nacional da Criança (DNCr) criado em 1940 para coordenar todas as atividades relativas a proteção à maternidade, à infância e à adolescência e o Serviço de Assistência a Menores (S.A.M.) criado em 1941 para superintender todo o serviço de amparo a menores desvalidos e delinqüentes, buscando sempre identificar que noções de psicologia que se faziam aí presentes. À guisa de conclusão, compartilho descobertas, encontros e desencontros proporcionados pela realização deste trabalho. / This thesis consists of a bibliographical and documental investigation about the infancy assistance and protection policies in Brazil. Related to this question, I researched historical lines since the colonial period up to the end of the so called Vargas Era. I start this historical course at the moment in which the children abandonment was not considered as a problem, and mechanisms worked as protection by proximity; I go back to the 1930s, when physicians and jurists mobilize themselves towards the underaged assistance and protection organization, which contributed to the creation of other attendance models, based on social assistance and on the State protection. At his point I make a concise analysis of Getúlio Vargas arrival at government and of his stay as president until 1945. Following this, I discuss the ocurred changes in the relationship structures between capital and work in the capitalist european society, when the social was configured as a new knowledge domain which allowed the emergence of the so caleed social professionals, pointing to similarities with the ocurred process in Brazil during the Vargas Era. Then, the analysis focuses itself in the creation and implementation movements of specific actions to treat the called not assisted child during the New State, implemented from the operation of two organs: the National Child Department (NCD) created in 1940 to coordinate all activities related to the protection of motherhood, infancy and adolescence and the Underaged Assistance Servic (UAS) created in 1941 to superintend all the services to assist unprotected underaged and delinquents , always searching to identify which psychology conceptions were present in both of them. As Conclusion, I share the foundings, encounters and discordances allowed by the realization of this work.
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Σχεδόν πλήρως αναλυόμενα στοχαστικά συστήματα και εφαρμογές / Nearly completely decomposable stochastic systems and applicationsΝικολακόπουλος, Αθανάσιος Ν. 11 June 2013 (has links)
Το θέμα της παρούσας μεταπτυχιακής διπλωματικής εργασίας είναι η εφαρμογή της θεωρίας των Σχεδόν Πλήρως Αναλυόμενων Στοχαστικών Συστημάτων (Nearly Completely Decomposable) σε μία σειρά προβλημάτων στα οποία παραδοσιακές προσεγγίσεις αποδεικνύονται ερμηνευτικά στείρες και υπολογιστικά κοστοβόρες. Στο πρώτο μέρος της διπλωματικής αφού κάνουμε μία διαισθητικού τύπου παρουσίαση της ιδέας της decomposability και συνοψίσουμε τα απαραίτητα στοιχεία του θεωρητικού υποβάθρου που χρησιμοποιούμε στα πλαίσια της εργασίας, παραθέτουμε τονπυρήνα της θεωρίας της decomposability, όπως αυτή θεμελιώνεται μαθηματικά από τον Courtois στην κλασική του μονογραφία. Τέλος, παραθέτουμε και μία υλοποίηση του KMS αλγορίθμου Συσσωμάτωσης/Αποσυσσωμάτωσης, για τη λύση NCD συστημάτων.
Το δεύτερο μέρος του συγγράμματος, είναι αφιερωμένο στην εφαρμογή της NCD σε δύο ενδιαφέροντα προβλήματα εκτίμησης απόδοσης υπολογιστικών συστημάτων. Συγκεκριμένα, μελετούμε μία ιδιότυπη ουρά που εξυπηρετεί πελάτες διαφορετικών κλάσεων, με τις ανά κλάση αφίξεις να χαρακτηρίζονται από εναλλαγές μεταξύ περιόδων ηρεμίας και κινητικότητας και την εξυπηρέτηση να γίνεται σε δέσμες πελατών της ίδιας κλάσης. Το κίνητρο για τη μελέτη αυτής της ουράς εντοπίζεται στη bursty φύση της μεταγωγής πακέτων στα σύγχρονα δίκτυα αλλά και στους reassembly buffers των multicluster πολυεπεξεργαστικών συστημάτων. Η ανάλυση της ουράς με παραδοσιακές τεχνικές οδηγεί αναπόφευκτα σε μαρκοβιανή αλυσίδα πολύ μεγάλου χώρου κατάστασης. Εμείς, ξεκινάμε από το πλήρες στοχαστικό μητρώο και αφού διαμερίσουμε κατάλληλα το χώρο καταστάσεων, αποδεικνύουμε ικανές συνθήκες υπό τις οποίες το αρχικό σύστημα είναι δυνατόν να αναλυθεί σε πολλαπλά επίπεδα υποσυστημάτων, η αυτόνομη ανάλυση των οποίων δίνει μία πολύ καλή προσέγγιση της στάσιμης κατανομής του αρχικού συστήματος. Επίσης, παραθέτουμε και αποδεικνύουμε μία ικανή συνθήκη για μηδενικό σφάλμα προσέγγισης και την ερμηνεύουμε σε όρους προδιαγραφών του προβλήματος. Τέλος, θεωρούμε μία ειδική συμμετρική εκδοχή για την οποία καταφέρνουμε να δώσουμε μία κλειστή έκφραση της κατανομής πληρότητας της ουράς συναρτήσει της λύσης των υποσυστημάτων.
Για να δείξουμε την απλοποίηση της ανάλυσης που επιφέρει η χρήση του NCD μοντέλου θεωρούμε ένα σενάριο για το οποίο προχωρούμε την ανάλυση σε βάθος και καταφέρνουμε να εξάγουμε χρήσιμες μετρικές στις οποίες, σε αντίθετη περίπτωση, θα ήταν ιδιαίτερα επίπονο να καταλήξει κανείς. Συγκεκριμένα, υπολογίζουμε την πιθανότητα blocking και δείχνουμε πως αυτή μειώνεται σχεδόν εκθετικά με το μέγεθος της ουράς. Βλέπουμε τελικά πως η εκμετάλλευση της NCD ιδιότητας από τη μία διευκολύνει την ανάλυση και από την άλλη παρέχει ανεκτίμητη διαίσθηση σχετικά με τη μεταβατική συμπεριφορά του συστήματος προς την κατάσταση στατιστικής ισορροπίας.
Το δεύτερο μέρος της διπλωματικής κλείνει με τη μελέτη κριτηρίων υπό τα οποία, πολυεπεξεργαστικά συστήματα που χωρίζονται σε ομάδες ισχυρά αλληλεπιδρώντων επεξεργαστών, μπορούν να αναλυθούν με χρήση της θεωρίας NCD. Είναι γνωστό πως στα δίκτυα ουρών αναμονής συγκρίσιμων ρυθμών εξυπηρέτησης, η NCD του μητρώου πιθανοτήτων δρομολόγησης συνεπάγεται την NCD του δικτύου. Εμείς, θεωρούμε μία ειδική περίπτωση τέτοιων συστημάτων για την οποία δείχνουμε ένα, εύκολο να ελεγχθεί, κριτήριο για NCD. Τέλος, εξετάζουμε βαθύτερα το σφάλμα της προσέγγισης, και χρησιμοποιώντας ένα πρόσφατο αποτέλεσμα της θεωρίας των σχεδόν ασύζευκτων μαρκοβιανών αλυσίδων δίνουμε έναν επιπλέον ποιοτικό περιορισμό που πρέπει να ικανοποιούν τα εν λόγω συστήματα για να πάρει κανείς ικανοποιητική προσέγγιση από την ανάλυσή τους σε ανεξάρτητα block.
Στο τρίτο μέρος της παρούσας εργασίας, εξετάζουμε την εφαρμογή της NCD στο πρόβλημα της κατάταξης ιστοσελίδων. Η πρόσφατη έρευνα έχει σχολιάσει την ειδική δομή του στοχαστικού μητρώου που προκύπτει από το γράφο του διαδικτύου· συγκεκριμένα, οι τοπολογικές ιδιότητες της αυτοoργάνωσης του Ιστού φαίνεται να παράγουν ένα στοχαστικό μητρώο με NCD δομή. Εμείς, αφού παραθέσουμε μία σύνοψη των μαθηματικών πίσω από τον αλγόριθμο PageRank, σχολιάζουμε και δικαιολογούμε διαισθητικά την NCD δομή του Ιστού αλλά και τη φύση των υποσυστημάτων. Τέλος, προτείνουμε έναν νέο αλγόριθμο κατάταξης με το όνομα NCDawareRank, o οποίος εκμεταλλεύεται την NCD ιδιότητα για να πετύχει ποιοτικότερο και ταχύτερο ranking. Μάλιστα, δίνουμε δύο εκδοχές του αλγορίθμου, μία σειριακή και μία παράλληλη, η οποία εκμεταλλεύεται την NCD του Ιστού και υπολογιστικά. Τα οφέλη που υπόσχεται ο NCDawareRank τα επιβεβαιώνουμε και πειραματικά εκτελώντας μία σειρά από πειράματα τόσο σε τεχνητά όσο και σε πραγματικά δεδομένα, αντιπαραβάλλοντας τα αποτελέσματα μας με αυτά του αλγορίθμου PageRank. O NCDawareRank φαίνεται μάλιστα να δίνει λύση σε ένα γνωστό πρόβλημα του PageRank: αυτό της μεροληψίας εναντίον νεοεισερχομένων σελίδων. Άλλο ένα, τέλος, παράπλευρο όφελος του αλγορίθμου NCDawareRank είναι αυτό της Levelwise κατάταξης, η οποία εκτός της σημασίας που έχει αφεαυτής, μπορεί να υποδείξει εξυπνότερο crawling ή ακόμα και αποδοτικότερα σχήματα ευρετηριοποίησης του Ιστού.
Στο τέταρτο και τελευταίο μέρος της διπλωματικής εφαρμόζουμε την NCD στην εύρεση των στοχαστικά ευσταθών καταστάσεων μίας κατηγορίας εξελικτικών παιγνίων στα οποία εμφανίζονται πολυεπίπεδες στρατηγικές δυναμικές. Αφού παραθέσουμε κάποιες πρόσφατες παρατηρήσεις από τη βιβλιογραφία της οικονομετρίας σχετικά με την αξιοποίηση της NCD στην προσεγγιστική ανάλυσή τους, αποδεικνύουμε συνθήκες υπό τις οποίες είναι δυνατόν να πετύχει κανείς ακριβή ανάλυση. / The purpose of this master’s thesis is the application of the theory of Nearly Completelely
Decomposable stochastic systems to a number of interesting problems for which tra-
ditional techniques turn out to be both intuitively unappealing and computationally in-
tractable.
In the first part of this work, after introducing, the concept of decomposability in
an intuitive way and summarizing the essential elements of the theoretical background
that is necessary to follow the rest of the text, we present the fundamental mathematical
principles of NCD as established by Courtois in his classic monograph. Finally, we give
an implementation of the KMS iterative aggregation/disaggregation algorithm which is
commonly used for the solution of NCD systems.
The second part of the dissertation is devoted to the application of NCD to two inter-
esting problems of Computer Systems Performance Evaluation. Specifically, we study an
uncommon discrete time queue that serves customers from different classes, with the ar-
rivals of each class characterized by alternating busy and idle periods. The service is done
in batches of customers of the same class. The motivation behind the study of this queue,
lies in the bursty nature of packet switching, as well as in the modern reassembly buffers
of multicluster multiprocessor systems. The traditional analysis techniques of this queue
inevitably lead to Markov chains with very large state space. We begin with the complete
stochastic matrix and after careful partitioning of the state space, we give sufficient condi-
tions under which the original system can be analysed through multi level decomposition
into subsystems, the autonomous analysis of which results in a very good approximation
to the stationary distribution of the original system. Furthermore, we present and prove a
sufficient condition for an error-free approximation and we give an interpretation of this
condition in terms of the specifications of the problem. Finally, we consider a special sym-
metric version of the problem, for which we manage to derive a closed-form expression
for the queue’s occupancy distribution as a function of the steady state probabilities of the
subsystems.
To demonstrate the simplification of the analysis brought by the NCD model, we con-
sider a scenario in which we proceed to an in depth analysis and we manage to extract
useful metrics the derivation of which, would be considerably harder without exploiting
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Abstract
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NCD. Specifically, we calculate the blocking probability and we show that it decreases
almost exponentially with the size of the queue. From our analysis, it is clear that the
exploitation of the NCD model increases significantly our ability to understand the dy-
namics of our system and to interpret aspects of its transient behaviour towards statistical
equilibrium.
The second part of this work ends with the study of criteria under which multipro-
cessing systems, that can be divided into groups of strongly interacting processors, can be
analysed using the theory of NCD. It is known that in queueing networks with servers of
comparable service rates, the NCD of the routing probability matrix implies the NCD of
the network. We consider a special case of such systems and we derive an easy to check
criterion for NCD. Finally, we look deeper into the error analysis of this approach, and
using a recent result from the theory of nearly uncoupled Markov chains, we give an addi-
tional qualitative constrain to be met by these systems in order to get a good approximation
of their analysis into independent blocks.
In the third part of this paper, we examine the application of NCD to the problem of
ranking websites. Recent research has commented on the special structure of the stochastic
matrix which corresponds to the web-graph. In particular, the topological properties of the
Web seems to produce a NCD stochastic matrix. Here, after presenting briefly the mathe-
matical basis of PageRank, we give a linear algebraic as well as an intuitive justification of
the NCD Web structure and we discuss the nature of the subsystems. Finally, we propose
a new ranking algorithm named NCDawareRank, which exploits NCD in order to achieve
a fairer and faster ranking. Indeed, we give two versions of the algorithm, one serial and
one parallel, in which we take advantage of the computational benefits of NCD as well.
The advantages of NCDawareRank are then confirmed experimentally through a series of
tests on both, artificial and real data. NCDawareRank seems to solve a known problem of
PageRank: the bias against new websites. Finally, another side benefit of our algorithm is
that it makes it easy to extract a level-wise ranking, which besides its importance in itself,
may indicate smarter crawling or even more sophisticated and efficient indexing schemes
of the Web.
Finally, in the fourth part of this work we apply NCD to the problem of finding
the stochastically stable states of a class of evolutionary games which involve multilevel
strategic dynamics. After presenting some interesting recent results coming from the lit-
erature of econometrics, we give conditions under which it is possible to get the exact
stochastically stable states through the use of NCD.
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Missionarische Relevanz der GemeindeberatungBrecht, Volker 30 November 2004 (has links)
Text in German / Over the last 30 years congregational counselling or church consultation has established itself in different manners in Germany. Most institutions of church consultation are methodologi-cally bound to organisational development. After a brief survey of the different kinds of con-gregational counselling the phenomenon itself is investigated. This is done by representation of two very different models of congregational counselling: The ,,Zentrum für Organisation-sentwicklung und Supervision (ZOS)" and the "Natural Church Development (NCD)". These concrete models are especially investigated in view of the missionary relevance of church consultation. In this way theological deficiencies are obvious. Further on both, the ZOS and the NCD, have another aspect in common: The relation between social sciences and theology, which is full of tensions, can be estimated as one of the central aspects of the two institutions. Not before the wider field of Church Development as locus vivendi of congregational coun-selling is analyzed, solutions can be found for this problem. On this total background it is pos-sible to summarize the missionary relevance of congregational counselling and to develop it. The search for a theological model for the theoretical and practical shaping of congregational counselling leads inevitably to "Communicative theology". This approach is processual in all its levels, shows responsibility to social sciences and is in total theologically established. So it fits for both, church and consultation processes. The missiological perspective of contextuali-zation is realised by Communicative theology. Thus the missionary relevance of congrega-tional counselling is supported. The application of Communicative theology is a model that makes it possible to speak of missionary relevance of congregational counselling. / Christian Spirituality, Church History and Missiology / D.Th.
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Counting prime polynomials and measuring complexity and similarity of informationRebenich, Niko 02 May 2016 (has links)
This dissertation explores an analogue of the prime number theorem for polynomials over finite fields as well as its connection to the necklace factorization algorithm T-transform and the string complexity measure T-complexity. Specifically, a precise asymptotic expansion for the prime polynomial counting function is derived. The approximation given is more accurate than previous results in the literature while requiring very little computational effort. In this context asymptotic series expansions for Lerch transcendent, Eulerian polynomials, truncated polylogarithm, and polylogarithms of negative integer order are also provided. The expansion formulas developed are general and have applications in numerous areas other than the enumeration of prime polynomials.
A bijection between the equivalence classes of aperiodic necklaces and monic prime polynomials is utilized to derive an asymptotic bound on the maximal T-complexity value of a string. Furthermore, the statistical behaviour of uniform random sequences that are factored via the T-transform are investigated, and an accurate probabilistic model for short necklace factors is presented.
Finally, a T-complexity based conditional string complexity measure is proposed and used to define the normalized T-complexity distance that measures similarity between strings. The T-complexity distance is proven to not be a metric. However, the measure can be computed in linear time and space making it a suitable choice for large data sets. / Graduate / 0544 0984 0405 / nrebenich@gmail.com
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Compression Based Analysis of Image Artifacts: Application to Satellite ImagesRoman-Gonzalez, Avid 02 October 2013 (has links) (PDF)
This thesis aims at an automatic detection of artifacts in optical satellite images such as aliasing, A/D conversion problems, striping, and compression noise; in fact, all blemishes that are unusual in an undistorted image. Artifact detection in Earth observation images becomes increasingly difficult when the resolution of the image improves. For images of low, medium or high resolution, the artifact signatures are sufficiently different from the useful signal, thus allowing their characterization as distortions; however, when the resolution improves, the artifacts have, in terms of signal theory, a similar signature to the interesting objects in an image. Although it is more difficult to detect artifacts in very high resolution images, we need analysis tools that work properly, without impeding the extraction of objects in an image. Furthermore, the detection should be as automatic as possible, given the quantity and ever-increasing volumes of images that make any manual detection illusory. Finally, experience shows that artifacts are not all predictable nor can they be modeled as expected. Thus, any artifact detection shall be as generic as possible, without requiring the modeling of their origin or their impact on an image. Outside the field of Earth observation, similar detection problems have arisen in multimedia image processing. This includes the evaluation of image quality, compression, watermarking, detecting attacks, image tampering, the montage of photographs, steganalysis, etc. In general, the techniques used to address these problems are based on direct or indirect measurement of intrinsic information and mutual information. Therefore, this thesis has the objective to translate these approaches to artifact detection in Earth observation images, based particularly on the theories of Shannon and Kolmogorov, including approaches for measuring rate-distortion and pattern-recognition based compression. The results from these theories are then used to detect too low or too high complexities, or redundant patterns. The test images being used are from the satellite instruments SPOT, MERIS, etc. We propose several methods for artifact detection. The first method is using the Rate-Distortion (RD) function obtained by compressing an image with different compression factors and examines how an artifact can result in a high degree of regularity or irregularity affecting the attainable compression rate. The second method is using the Normalized Compression Distance (NCD) and examines whether artifacts have similar patterns. The third method is using different approaches for RD such as the Kolmogorov Structure Function and the Complexity-to-Error Migration (CEM) for examining how artifacts can be observed in compression-decompression error maps. Finally, we compare our proposed methods with an existing method based on image quality metrics. The results show that the artifact detection depends on the artifact intensity and the type of surface cover contained in the satellite image.
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Ignoring a Silent Killer: Obesity & Food Security in the Caribbean (Case Study: Barbados)MacDonald, Tara 05 September 2012 (has links)
Obesity and obesity-related diseases – such as type 2 diabetes – have become the most crucial indicators of population health in the 21st century. Formerly understood as ‘diseases of affluence’, obesity is now prevalent in the Global South posing serious risk to socioeconomic development. This is particularly true for rapidly developing countries where nutrition transitions are most apparent. There are many factors which impact on risk of obesity (e.g. gender, culture, environment, socioeconomic status, biological determinants). The problem is further aggravated within small island developing states where food security is exacerbated by factors associated with globalization and development. The thesis examines the surge of obesity and type 2 diabetes within Caribbean populations, using Barbados as a case study. A holistic approach was applied using an ecological health model. Moving away from the lifestyle model, the theoretical framework underpinning included sub-theories (e.g. social constructivism, feminism, post-colonial theory, concepts of memory and trauma).
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Ignoring a Silent Killer: Obesity & Food Security in the Caribbean (Case Study: Barbados)MacDonald, Tara 05 September 2012 (has links)
Obesity and obesity-related diseases – such as type 2 diabetes – have become the most crucial indicators of population health in the 21st century. Formerly understood as ‘diseases of affluence’, obesity is now prevalent in the Global South posing serious risk to socioeconomic development. This is particularly true for rapidly developing countries where nutrition transitions are most apparent. There are many factors which impact on risk of obesity (e.g. gender, culture, environment, socioeconomic status, biological determinants). The problem is further aggravated within small island developing states where food security is exacerbated by factors associated with globalization and development. The thesis examines the surge of obesity and type 2 diabetes within Caribbean populations, using Barbados as a case study. A holistic approach was applied using an ecological health model. Moving away from the lifestyle model, the theoretical framework underpinning included sub-theories (e.g. social constructivism, feminism, post-colonial theory, concepts of memory and trauma).
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Fast Low Memory T-Transform: string complexity in linear time and space with applications to Android app store security.Rebenich, Niko 27 April 2012 (has links)
This thesis presents flott, the Fast Low Memory T-Transform, the currently fastest and most memory efficient linear time and space algorithm available to compute the string complexity measure T-complexity. The flott algorithm uses 64.3% less memory and in our experiments runs asymptotically 20% faster than its predecessor. A full C-implementation is provided and published under the Apache Licence 2.0. From the flott algorithm two deterministic information measures are derived and applied to Android app store security. The derived measures are the normalized T-complexity distance and the instantaneous T-complexity rate which are used to detect, locate, and visualize unusual information changes in Android applications. The information measures introduced present a novel, scalable approach to assist with the detection of malware in app stores. / Graduate
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