A new automatic algorithm for sampling from 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. The proposed algorithm is the first black-box method that works for unbounded densities suggested in the literature. (author's abstract) / Series: Research Report Series / Department of Statistics and Mathematics

This thesis explores a border security system based on agent-based modeling and simulation (ABMS). The ABMS software platform, map aware non-uniform automata, is used to model various scenarios and evaluate the border security system given a set of infiltrators who have evolutionary behavior governed by a genetic algorithm (GA). The GA is used to represent adaptive behavior of the enemy when the friendly force has deployed our border security at a maximum level. By using a near optimal Latin hypercube design, our simulation runs are implemented efficiently and the border security system is analyzed using four different kinds of measures of effectiveness. / text

Ο εξοπλισμός και οι αγωγοί που μεταφέρουν την υψηλή τάση ακολουθούν συγκεκριμένες τιμές ασφάλειας και ελέγχου. Με τον όρο υπερτάσεις εννοούμε τις τάσεις που εμφανίζονται στα ηλεκτρικά δίκτυα και που συνήθως έχουν εύρος μεγαλύτερο από εκείνο της κανονικής τάσης λειτουργίας. Οι υπερτάσεις έχουν κατά κανόνα ανώμαλη μορφή και είναι ικανές να προκαλέσουν διηλεκτρικές καταπονήσεις μεγάλου μεγέθους στις μονώσεις ενός συστήματος. Κατά τον σχεδιασμό της μόνωσης ενός συστήματος υπάρχουν δύο εξαιρετικά σημαντικές παράμετροι που πρέπει να ληφθούν υπ’όψην από τους κατασκευαστές: 1) Ο καθορισμός της μορφής των τάσεων που καταπονούν την μόνωση 2) Ο καθορισμός της αντοχής της μόνωσης όταν υφίσταται καταπόνηση από συγκεκριμένες μορφές τάσεων. Σκοπός της παρούσας εργασίας είναι η ανάλυση της καταπόνησης που υφίσταται διάκενο ακίδα-πλάκα συνολικού μήκους 6cm στο οποίο παρεμβλήθηκε μετακινούμενο διάφραγμα. Τα συμπεράσματα που εξήχθησαν αφορούν την μελέτη της τάσης διάσπασης και τον τρόπο με τον οποίο αυτή μεταβάλλεται σε σχέση με την γεωμετρία του διακένου αλλά και τις ατμοσφαιρικές συνθηκες. Τα συμπεράσματα που προκύπτουν από την ανάλυση της καταπόνησης που υφίσταται διάκενο ακίδας-πλάκας είναι ότι καθώς απομακρύνεται το διάφραγμα από την ακίδα η τάση διάσπασης μειώνεται. Αξίζει επίσης να σημειωθεί ότι όσο πλησιάζει το διάφραγμα την ακίδα μειώνεται η τυχαιότητα του φαινομένου της διάσπασης πράγμα το οποιό σημαίνει πως ο σχεδιασμός ενός συστήματος μόνωσης δύναται να γίνει πιο ακριβής. Τέλος παρατηρείται ότι ανάμεσα σε σετ μετρήσεων με ίδια απόσταση διαφράγματος από την ακίδα υπάρχει μια απόκλιση στις τιμές της U50%. Αυτή η απόκλιση οφείλεται σε διάφορους παράγοντες. Ένας εξ’αυτών είναι η μικρή μεταβολή των ατμοσφαιρικών συνθηκών κατά την χρονική απόσταση που παρεμβλήθηκε ανάμεσα στα σετ μετρήσεων. Έναν δεύτερο παράγοντα αποτελούν οι πιθανές υπερπηδήσεις που συνέβησαν κατά την διάρκεια των επιβολών τάσης στο διάκενο. / The equipment and conductors that "carry" high voltage are taking specific values of security and control. Using the term, hyper-voltage, the researchers mean those voltages that appear in electricity networks and they usually have a width value greater than the normal operating voltage. Most of the times, hyper-voltages are typically have irregular form and they are capable of causing large dielectric stresses in the insulation of a system. When designing an insulation system there are two very important parameters that have to be taken under consideration by the manufacturers: 1) The determination of a voltage form that stresses the insulation equipment 2) The determination of the insulation resistance when there is strain from specific voltage forms. The purpose of this paper is to analyze the voltage stress that is happening in a 6cm gap of pin-plate which was inserted by removable diaphragm. The conclusions drawn are concerning the study of breakdown voltage and how it changes with respect to the geometry of the gap and the atmospheric conditions. One conclusion that arises from the stress analysis of the pin-plate gap is that when the diaphragm is moving away from the pin the breakdown voltage is decreasing. It is also worth noting that as the diaphragm is moving towards the pin, the breakdown phenomenon is becoming less random. This means that the design of an insulation system can be made more accurate. Another conclusion is related to the discrepancy in the values of U50% between different sets of measurements. The distance between the diaphragm and the spike is influencing the above observation. This discrepancy is due to several factors. The first factor is related to the small change of weather conditions during the different sets of measurements. The second factor is related to the possible jumps that occurred during the voltage imposition in the gap.

Η παρούσα εργασία πραγματεύεται το σχεδιασμό και τη δημιουργία εκπαιδευτικού λογισμικού για τη διδασκαλία της ομοιόμορφης σύγκλισης ακολουθιών πραγματικών συναρτήσεων. Η ομοιόμορφη σύγκλιση ακολουθιών πραγματικών συναρτήσεων είναι ένα μαθηματικό ζήτημα που αντιμετωπίζουν οι δευτεροετείς φοιτητές των Μαθηματικών Τμημάτων. Η εμπειρία τόσο των φοιτητών όσο και των εκπαιδευτικών έχει δείξει ότι η μάθηση αυτού του αντικειμένου με παραδοσιακές μεθόδους διδασκαλίας (π.χ., από έδρας διδασκαλία, ή εγχειρίδιο) παρουσιάζει δυσκολία στην κατασκευή των γραφικών παραστάσεων ακολουθιών πραγματικών συναρτήσεων. Στόχος του λoγισμικού UNICORN (UNIform COnvergence Resource Navigator) είναι να καλύψει αυτό το εκπαιδευτικό κενό διδάσκοντας την έννοια της ομοιόμορφης σύγκλισης μέσα από την κατασκευή και ανάλυση των γραφικών παραστάσεων. Ο σχεδιασμός του λογισμικού βασίστηκε κυρίως στην κονστρουκτιβιστική θεωρία μάθησης (constructivism). Το UNICORN είναι ένα ανοιχτό περιβάλλον που επιδιώκει να εμπλέξει ενεργά το φοιτητή στη μαθησιακή διεργασία και να ενεργοποιήσει τη δημιουργικότητά του. Η πλοήγηση του φοιτητή μέσα στο λογισμικό υποβοηθείται εν μέρει από κατευθυντήριες ερωτήσεις και διορθωτικό σχολιασμό (feedback), που βασίζονται στη θεωρία μάθησης του ινστραξιονισμού (instructionism). Το UNICORN κατασκευάστηκε με τη χρήση των προγραμμάτων Mathematica 4.0 (γραφικές παραστάσεις) και Macromedia Director 8.5 (κοινή επιφάνεια – interface), το υποπρόγραμμα BuddyApi (επικοινωνία UNICORN-Mathematica), και τη γλώσσα προγραμματισμού Lingo (λειτουργίες interface). Το λογισμικό είναι έτοιμο για πιλοτική χρήση και αξιολόγηση ως συμπληρωματικό εκπαιδευτικό υλικό και/ή ως εργαλείο μάθησης από απόσταση. / The present work discusses the design and development of educational software for teaching the uniform convergence of sequences of real functions. This advanced mathematical topic is taught during the second year of undergraduate studies in Mathematics Departments of Greek academic institutions. The experiences of both students and instructors agree that this topic is difficult to understand by using only traditional teaching methods (such as a lecture and the use of the blackboard). The reason is that it is difficult to draw manually graphical representations of the sequences of real functions. The educational software described here (named UNIform COnvergence Resource Navigator, or UNICORN) aims to cover this educational gap by teaching the concept of the uniform convergence of sequences of real functions through the construction and analysis of the respective graphical representations. The design of the educational software was mainly based on the teaching theory of constructivism. UNICORN is an open environment that aims to actively involve the user/learner in the learning process and to activate her creativity. The student’s navigation through the software is assisted by instructional questions and feedback, both of which are based on the learning theory of instructionism. UNICORN was developed with the help of Mathematica 4.0 (graphical representations), Director 8.5 (interface), and BuddiApi (communication between UNICORN and Mathematica). The software is ready for pilot testing and evaluation as supplementary teaching material and/or as a tool for long distance learning.

Remiantis ugdymo filosofinės, socialinės, pedagoginės bei istorinės literatūros analize, darbe keliamas tikslas ištirti mokyklinę uniformą bendruomeniškumo aspektu. Tikslui pasiekti teorinėje darbo dalyje buvo suformuluoti pagrindiniai uždaviniai: išsiaiškinti bendruomeniškumo raiškos visuomenėje ir bendruomeniškumo ugdymo mokykloje ypatumus; atskleisti mokyklinės uniformos istorinius metmenis ir jos stilistinius ypatumus sąlygojančius sociokultūrinius veiksnius bei įvertinti mokyklinės uniformos, kaip bendruomeniškumą konsoliduojančio veiksnio, reikšmę pedagoginiu, socialiniu ir estetiniu aspektais. Paskutinėje darbo dalyje pateikti empirinio tyrimo duomenys. Tyrimu buvo siekta nustatyti uniformos bendruomeniškumą lemiančius motyvus mokyklinės bendruomenės narių požiūriu. Darbas baigiamas keturiomis teorinę ir empirinę jo dalį apibendrinančiomis išvadomis. Vykstant sparčioms socialinėms permainoms, bendruomeniškumo ugdymas tampa svarbiu edukologijos mokslų uždaviniu ir praktiniu rūpesčiu. Bendruomeniškumo raiška priklauso nuo žmonių socialinių, etinių, moralinių ir estetinių kompetencijų ir gebėjimų. Todėl pastebima, kad šių įgūdžių kryptingas formavimas turi prasidėti mokykloje. Tačiau mokykla – specifinė ugdomoji bendruomenė, jungianti įvairaus amžiaus, statuso ir išsilavinimo narius. Vadinasi, tokioje organizacijoje bendruomeniškumo raiškai ypatingai svarbi tampa pačios bendruomenės sukurta kultūra, susieta su jos istorija, tradicijomis, aplinka ir gyvenimo... [toliau žr. visą tekstą] / Following the analysis of the philosophical, social, educational and history sources on education, the research paper aims at examining a school uniform in terms of communal expression. With this end in view, the theoretical part of the paper sets forth the main tasks to find out characteristics of communal expression in society and of developinga sense of belonging to a schoolcommunity; to establishsocial and cultural factors which determined historical and stylistic features of a school uniform; and to assess the significance of a school uniform as the community consolidating factor in terms of education, society and aesthetics. The last part of the paper presents the empirical data. The study aims at identifying the communal aspects of a school uniform from the view of school community members. The paper ends with the four conclusions summarising theoretical and empirical parts of the research. With the sweeping social reforms, the development of a sense of belonging to a community is becoming a challenging task and a matter of concern for social science. Communal expression depends on social, ethic, moral and aesthetic competencies and skills of a person. Thus a school is considered to be a starting point for the purposeful development of the aforementioned capacities. On the other hand, a school represents a specific community which brings together people of different age, status and level of education. Hence the culture created by this community and related to its... [to full text]

Multivariate generalized linear mixed models (MGLMM) are used for jointly modeling the clustered mixed outcomes obtained when there are two or more responses repeatedly measured on each individual in scientific studies. The relationship among these responses is often of interest. In the clustered mixed data, the correlation could be present between repeated measurements either within the same observer or between different observers on the same subjects. This study proposes a series of in- dices, namely, intra, inter and total correlation coefficients, to measure the correlation under various circumstances of observations from a multivariate generalized linear model, especially for joint modeling of clustered count and continuous outcomes. Bayesian methods are widely used techniques for analyzing MGLMM. The need for noninformative priors arises when there is insufficient prior information on the model parameters. Another aim of this study is to propose an approximate uniform shrinkage prior for the random effect variance components in the Bayesian analysis for the MGLMM. This prior is an extension of the approximate uniform shrinkage prior. This prior is easy to apply and is shown to possess several nice properties. The methods are illustrated in terms of both a simulation study and a case example.

The maximum spacing (MSP) method, introduced by Cheng and Amin (1983) and independently by Ranneby (1984), is a general estimation method for continuous univariate distributions. The MSP method, which is closely related to the maximum likelihood (ML) method, can be derived from an approximation based on simple spacings of the Kullback-Leibler information. It is known to give consistent and asymptotically efficient estimates under general conditions and works also in situations where the ML method fails, e.g. for the three parameter Weibull model. In this thesis it is proved under general conditions that MSP estimates of parameters in the Euclidian metric are strongly consistent. The ideas behind the MSP method are extended and a class of estimation methods is introduced. These methods, called generalized MSP methods, are derived from approxima­tions based on sum-functions of rath order spacings of certain information mea­sures, i.e. the ^-divergences introduced by Csiszår (1963). It is shown under general conditions that generalized MSP methods give consistent estimates. In particular, it is proved that generalized MSP methods give L1 consistent esti­mates in any family of distributions with unimodal densities, without any further conditions on the distributions. Other properties such as distributional robust­ness are also discussed. Several limit theorems for sum-functions of rath order spacings are given, for ra fixed as well as for the case when ra is allowed to in­crease to infinity with the sample size. These results provide a strongly consistent nonparametric estimator of entropy, as well as a characterization of the uniform distribution. Further, it is shown that Cressie's (1976) goodness of fit test is strongly consistent against all continuous alternatives. / digitalisering@umu

The research on tribology and wear of the metals and composites has always been the topic of interest to understand the behavior and life of them. The wear of the materials with three-body contact has been of particular interest because the wear debris generated due to the wear and tear between the contact surfaces in constant motion will aggravate the wear rate of the contact surfaces. Hence it would be interesting to understand the stress distribution inside the materials with three-body contact. The current research presents the stress distribution within the materials which are in three-body contact modeling them as plain-strain problems with three different models viz., point force model, uniform pressure model and Hertzian Pressure model. The stress distribution of all the three cases are numerically computed and compared and the stress intensity factor is calculated in each case.

Compared with algorithms specialized for a single distribution universal (also called automatic or black-box) algorithms for continuous distributions were relatively seldom discussed. But they have important advantages for the user: One algorithm coded and tested only once can do the same or even more than a whole library of standard routines. It is only necessary to have a program available that can evaluate the density of the distribution up to a multiplicative factor. In this paper we show that transformed density rejection is well suited to construct universal algorithms suitable for correlation induction which is important for variance reduction in simulation. (author's abstract) / Series: Preprint Series / Department of Applied Statistics and Data Processing

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