In the first part of this thesis, we present the first non-trivial small value estimate that applies to an algebraic group of dimension 2 and which involves large sets of points. The algebraic group that we consider is the product ℂ× ℂ*, of the additive group ℂ by the multiplicative group ℂ*. Our main result assumes the existence of a sequence (PD)D ≥1 of non-zero polynomials in ℤ [X1, X2] taking small absolute values at many translates of a fixed point (ξ, η) in ℂ × ℂ* by consecutive multiples of a rational point (r, s) ∈ (ℚ*)2 with s = ±1. Under precise conditions on the size of the coefficients of the polynomials PD, the number of translates of (ξ, η) and the absolute values of the polynomials PD at these points, we conclude that both ξ and η are algebraic over ℚ. We also show that the conditions that we impose are close from being best possible upon comparing them with what can be achieved through an application of Dirichlet’s box principle. In the second part of the thesis, we consider points of the form θ = (1,θ1 , . . . ,θd-1 ,ξ) where {1,θ1 , . . . ,θd-1 } is a basis of a real number field K of degree d ≥ 2 over ℚ and where ξ is a real number not in K. Our main results provide sharp upper bounds for the uniform exponent of approximation to θ by rational points, denoted λ ̂(θ), and for its dual uniform exponent of approximation, denoted τ ̂(θ). For d = 2, these estimates are best possible thanks to recent work of Roy. We do not know if they are best possible for other values of d. However, in Chapter 2, we provide additional information about rational approximations to such a point θ assuming that its exponent λ ̂(θ) achieves our upper bound. In the course of the proofs, we introduce new constructions which are interesting by themselves and should be useful for future research.

A new algorithm for sampling from largely abitrary monotone, unbounded densities is presented. The user has to provide a program to evaluate the density and its derivative and the location of the pole. Then the setup of the new algorithm constructs different hat functions for the pole region and for the tail region, respectively. For the pole region a new method is developed that uses a transformed density rejection hat function of the inverse density. As the order of the pole is calculated in the setup, conditions that guarantee the correctness of the constructed hat functions are provided. Numerical experiments indicate that the new algorithm works correctly and moderately fast for many different unbounded densities. (c) ACM, (2007). This is the author's version of the work. It is posted here by permission of ACM for your personal use. Not for redistribution. (author's abstract) / Series: Research Report Series / Department of Statistics and Mathematics

A sweep-plane algorithm by Lawrence for convex polytope computation is adapted to generate random tuples on simple polytopes. In our method an affine hyperplane is swept through the given polytope until a random fraction (sampled from a proper univariate distribution) of the volume of the polytope is covered. Then the intersection of the plane with the polytope is a simple polytope with smaller dimension. In the second part we apply this method to construct a black-box algorithm for log-concave and T-concave multivariate distributions by means of transformed density rejection. (author's abstract) / Series: Preprint Series / Department of Applied Statistics and Data Processing

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The model training algorithm is a critical component in the statistical pattern recognition approaches which are based on the Bayes decision theory. Conventional applications of the Bayes decision theory usually assume uniform error cost and result in a ubiquitous use of the maximum a posteriori (MAP) decision policy and the paradigm of distribution estimation as practice in the design of a statistical pattern recognition system. The minimum classification error (MCE) training method is proposed to overcome some substantial limitations for the conventional distribution estimation methods. In this thesis, three aspects of the MCE method are generalized. First, an optimal classifier/recognizer design framework is constructed, aiming at minimizing non-uniform error cost.A generalized training criterion named weighted MCE is proposed for pattern and speech recognition tasks with non-uniform error cost. Second, the MCE method for speech recognition tasks requires appropriate management of multiple recognition hypotheses for each data segment. A modified version of the MCE method with a new approach to selecting and organizing recognition hypotheses is proposed for continuous phoneme recognition. Third, the minimum verification error (MVE) method for detection-based automatic speech recognition (ASR) is studied. The MVE method can be viewed as a special version of the MCE method which aims at minimizing detection/verification errors. We present many experiments on pattern recognition and speech recognition tasks to justify the effectiveness of our generalizations.

Thesis (Ph.D.)--University of Cincinnati, 2008. / Committee/Advisors: David Herron PhD (Committee Chair), David Minda PhD (Committee Member), Nageswari Shanmugalingam PhD (Committee Member). Includes bibliographical references and abstract.

Thesis (M.S.)--Duquesne University, 2004. / Title from document title page. Abstract included in electronic submission form. Includes bibliographical references (p. 24-25) and index.

Η εργασία αποτελεί μελέτη της λειτουργίας των caches, χρησιμοποιώντας μια συγκεκριμένη cache δομή. Η εργασία αυτή έχει σα σκοπό τη μελέτη των κρυφών μνημών με μη ομοιογενή χρόνο προσπέλασης στα διάφορα «φυσικά» σημεία της επιφάνειάς της. Αντικειμενικός σκοπός των κρυφών αυτών μνημών, είναι να τοποθετούνται τα δεδομένα που χρησιμοποιούνται συχνότερα, σε θέσεις που βρίσκονται κοντύτερα στον επεξεργαστή και έχουν λιγότερες διασυνδέσεις καλωδίων, άρα έχουν και το μικρότερο χρόνο προσπέλασης. Όταν αυτό είναι επιτεύξιμο, τα δεδομένα που χρησιμοποιούνται περισσότερες φορές, χρειάζονται τον ελάχιστο χρόνο για την προσπέλασή τους. Για το σκοπό αυτό επιλέξαμε έναν ήδη προτεινόμενο μηχανισμό, τον οποίο αναλύσαμε εκτενώς. Η επιλογή αυτή δεν έγινε τυχαία, αλλά επιλέξαμε έναν μηχανισμό που διαφέρει στη λογική από τη γενική έννοια των εν λόγω κρυφών μνημών (NUCA), έχοντας σαν κύρια διαφορά ότι διαφοροποιεί εντελώς τη διαχείριση του tag από εκείνη του data array, αντίθετα με τις γενικότερης έννοιας NUCA μνήμες. Εκτός από τη λειτουργία της δομής αυτής όπως είχε προταθεί, εισάγουμε στη διαχείριση των δεδομένων και την πληροφορία της πρόβλεψης για να δούμε πως μπορεί να επιδράσει στην απόδοση και αν μπορούμε να καταφέρουμε κάποια βελτίωση. / This work is a study of cache memories, using a specific cache structure. Its goal is to study cache memories with non-uniform access time for all blocks throughout the cache surface (NUCA). The objective of these "hidden" memories is to put the most often used data at the closest to processor positions (blocks), which have fewer wire connections and therefore smaller access time. Whenever this is feasible, the data used most often need are accessed in the least possible amount of time. For this purpose we chose an already proposed mechanism, which was analyzed extensively. The selection was not random, but chose a structure that differs from the usual NUCA structure, having as main diferrence that it completely decouples the tag array management from the data array, contrary to the general concept of NUCA memories. Apart from this strucure's function as originally proposed, we introduced prediction in both tag and data arrays management to see how it can affect performance and whether we can achieve some performance improvement.

Η παρούσα εργασία ασχολείται με την εξομοίωση σε προγραμματιστικό περιβάλλον, της λειτουργίας συστοιχιών ηχείων κάθετης διάταξης και συγκεκριμένα για τις περιπτώσεις ευθύγραμμων (Uniform) και υβριδικού τύπου (J-Shaped) συστοιχιών, σε περιβάλλον ανοιχτών και κλειστών χώρων. Οι εξομοιώσεις που υλοποιήθηκαν επιτρέπουν την αξιολόγηση και σύγκριση των συστοιχιών σε θέματα εκπομπής, εστιάζοντας στην ηχητική κάλυψη των επιπέδων ακρόασης. Επιπλέον, αναπτύσσονται τα εργαλεία για την εξομοίωση και μελέτη του διάχυτου πεδίου που παράγεται κατα τη λειτουργία των συστοιχιών σε κλειστούς χώρους. / The current thesis is about simulating the function of Uniform and J-Shaped line arrays in open and closed space. It also allows the comparison among between the two types af arrays in terms of beaming and sound coverage especially at the audience planes. Furthermore, tools of simulation of the diffuse field are being developed.

The aim of this study is to quantify principals' professional opinion on school uniform. Qualitative interviews were conducted with five primary school principals to ascertain what they consider the phrase 'school uniform' to imply. The principals' arguements for and against scool uniform were investigated, in addition to how they gauged the importance of the discussion of school uniform. The qualitative data collected was subjected to a discourse analysis, in order to identify the principals' implicit motivations. The results of this study show that the principals interviewed did not consider school uniform to be a particularly hot topic, and none of them had previously read any research regarding school uniform. All of the principals mentioned the fact that a school uniform infringes on children's rights, namely their freedom of expression. None of the principals mentioned arguments for school uniform on the grounds of improved discipline, grades or attendance but rather mentioned the possibility that school uniform might 'level the playing field' with regard to children's clothing. This indicates that Swedish principals do not experience issues regarding poor discipline, grades or attendance to the degree that potential resolutions have been researched. Instead the issues that the principals experience pertain to differences in children's socioeconomic backgrounds, and the challenges this encompases; as such the principals were more interested in potential resolutions so such issues. That being said, none of the principals interviewed actually believed that school uniform would resolve the differences between children from different socioeconomic classes.