• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 71
  • 19
  • 16
  • 10
  • 7
  • 6
  • 3
  • 2
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 152
  • 46
  • 36
  • 23
  • 22
  • 19
  • 15
  • 15
  • 15
  • 15
  • 15
  • 13
  • 13
  • 12
  • 12
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Discussão sobre tamanho de fragmento e efeitos de isolamento com uso da equação Fisher - Kolmogorov

SILVA JÚNIOR, José Luiz Santos da 31 August 2011 (has links)
Submitted by Irene Nascimento (irene.kessia@ufpe.br) on 2016-08-24T17:57:59Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) dissertaçãosuper_final_(1).pdf: 1088878 bytes, checksum: f1d95f7419b99281751c7ea750e47cf8 (MD5) / Made available in DSpace on 2016-08-24T17:57:59Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) dissertaçãosuper_final_(1).pdf: 1088878 bytes, checksum: f1d95f7419b99281751c7ea750e47cf8 (MD5) Previous issue date: 2011-08-31 / CAPES / Nesta dissertação é apresentada uma solução estacionária para um modelo de dinâmica populacional de uma única espécie, considerando a dispersão da população num espaço heterogêneo e um crescimento logístico da população. No primeiro capítulo, para dar ao leitor alguma intimidade com os conceitos apresentados estudamos alguns modelos de dinâmica populacional de uma única espécie. Referimo-nos a uma única população para dizer que não analisamos aqui a interação entre diversas espécies. No segundo capítulo concentra-se a parte substancial do nosso trabalho. Na seção 1 apresentamos o modelo, na seção 2 apresentamos a solução estacionária para o problema e na seção 3 fazemos uma discussão sobre efeitos de isolamento para uma população. / This thesis presents a stationary solution to a model of population dynamics of a single species, considering the dispersion of biological population in a heterogeneous space and a logistic population growth. In the rst chapter, to give the reader some familiarity with the concepts presented study some models of population dynamics of a single species. We refer to a single population to say we do not analyze the interaction between di erent species. The second chapter focuses on the substantial part of our work. In Section 1 presents the problem and the model, section 2 presents the stationary solution to the problem and in Section 3 we make a discussion about isolation e ects on a population
12

Two Studies in the Stability of Taiwan Listed Stock Statistics-The Application of Nonparametric Method

Chuang, Ching-Chi 11 July 2002 (has links)
none
13

Performance Evaluation of Identification Methods for the Stress Calls of Squirrelfishes¡]Pisces:Holocentridae¡^

Tsai, Ying-Wei 25 January 2008 (has links)
In the study of sound identification, land animals such as birds and bats have been well investigated, and so are their habitats. On the other hand, sound making creatures in the ocean are much less researched. In this research, the stress calls of three Holocentridaes, Neoniphon sammara, Myripristis murdjan, and Sargocentron spinosissimum, who are commonly found in coral reefs, were recorded in water tank for analysis of sound characteristics. The averaged characteristic parameters of single pulse among three is around 410 Hz for the peak frequency, 100 Hz for the bandwidth, 0.07 dB/Hz for the slope, and duration of 0.05 s. As for the impulse train, averaged peak frequency is 415 Hz, 55 Hz for the bandwidth, 0.07 dB/Hz for the slope, and duration of 0.5 s. These parameters were first checked by the Kolmogorov-Smirnov Test to identify if each parameter follows normal distribution; the slopes of ascending and descending frequency and the total duration are not in normal distribution. The three parameters were later transferred so as to concentrate variances. Next, analysis of variance was applied on all characteristics to extract the significant parameters (including non transferred and transferred data), which were then tested by Stepwise Discriminat and Back-propagation Network. The identification rate of for single pulse with and without data transfer is 63% and 82% while pulse train is 57% and 73%. Both identification rates were raised up approximately 20% due to the data transfer. Both methods provide an reliable tool for marine sound identification, and the whole process of the study may be applied to another biological identification.
14

Decomposition and optimization in near-hierarchical boolean function systems /

Masum, Hassan, January 1900 (has links)
Thesis (Ph. D.)--Carleton University, 2003. / Includes bibliographical references (p. 226-237). Also available in electronic format on the Internet.
15

Modelo de Fisher-Kolmogorov em Dinâmica Populacional com Capacidade de Suporte Espacialmente Dependente

SILVA JÚNIOR, José Luiz Santos da 31 January 2011 (has links)
Made available in DSpace on 2014-06-12T18:31:12Z (GMT). No. of bitstreams: 2 arquivo7578_1.pdf: 735911 bytes, checksum: f459b01de36c59e7809bb426437d278f (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2011 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Nesta dissertação é apresentada uma solução estacionária para um modelo de dinâmica populacional de uma única espécie, considerando a dispersão da população num espaço heterogêneo e um crescimento logístico da população. No primeiro capítulo, para dar ao leitor alguma intimidade com os conceitos apresentados estudamos alguns modelos de dinâmica populacional de uma única espécie. Referimo-nos a uma única população para dizer que não analisamos aqui a interação entre diversas espécies. No segundo capítulo concentra-se a parte substancial do nosso trabalho. Na seção 1 apresentamos o modelo, na seção 2 apresentamos a solução estacionária para o problema e na seção 3 fazemos uma discussão sobre efeitos de isolamento para uma população.
16

Information and distances

Epstein, Samuel Randall 23 September 2015 (has links)
We prove all randomized sampling methods produce outliers. Given a computable measure P over natural numbers or infinite binary sequences, there is no method that can produce an arbitrarily large sample such that all its members are typical of P. The second part of this dissertation describes a computationally inexpensive method to approximate Hilbertian distances. This method combines the semi-least squares inverse techinque with the canonical modern machine learning technique known as the kernel trick. In the task of distance approximation, our method was shown to be comparable in performance to a solution employing the Nystrom method. Using the kernel semi-least squares method, we developed and incorporated the Kernel-Subset-Tracker into the Camera Mouse, a video-based mouse replacement software for people with movement disabilities. The Kernel-Subset-Tracker is an exemplar-based method that uses a training set of representative images to produce online templates for positional tracking. Our experiments with test subjects show that augmenting the Camera Mouse with the Kernel-Subset-Tracker improves communication bandwidth statistically significantly.
17

Some results on Kolmogorov-Loveland randomness

Petrovic, Tomislav 03 November 2022 (has links)
Whether Kolmogorov-Loveland randomness is equal to the Martin-Löf randomness is a well known open question in the field of algorithmic information theory. Randomness of infinite binary sequences can be defined in terms of betting strategies, a string is non-random if a computable betting strategy wins unbounded capital by successive betting on the sequence. For Martin-Löf randomness, a betting strategy makes a bet by splitting a set of sequences into any two clopen sets, and placing a portion of capital on one of them as a wager. Kolmogorov-Loveland betting strategies are more restricted, they bet on a value of the bit at some position they choose, which splits a set of sequences into two clopen sets, the sequences that have 0 at the chosen position and the sequences that have 1. In this thesis we consider betting strategies that when making a bet are restricted to split a set of sequences into two sets of equal uniform Lebesgue measure. We call this generalization of Kolmogorov-Loveland betting strategies the half-betting strategies. We show that there is a pair of such betting strategies such that for every non-Martin-Löf random sequence one of them wins unbounded capital (the pair is universal). Next, we define a finite betting game where the betting strategies bet on finite binary strings, and show that in this game Kolmogorov-Loveland betting strategies cannot increase capital by more than an arbitrary small amount on all strings on which the unrestricted betting strategy achieves arbitrary large capital. We also look at another relaxation of Kolmogorov-Loveland betting, where a betting strategy is allowed to access bits of the sequence within a set of positions a bounded number of times. We show that if this bound is less than ℓ - log ℓ for the first ℓ positions then a pair of such betting strategies cannot be universal. Furthermore, we show that, at least for some universal betting strategies, this bound is exponential.
18

Non-additive probabilities and quantum logic in finite quantum systems

Vourdas, Apostolos January 2016 (has links)
Yes / A quantum system Σ(d) with variables in Z(d) and with Hilbert space H(d), is considered. It is shown that the additivity relation of Kolmogorov probabilities, is not valid in the Birkhoff-von Neumann orthocomplemented modular lattice of subspaces L(d). A second lattice Λ(d) which is distributive and contains the subsystems of Σ(d) is also considered. It is shown that in this case also, the additivity relation of Kolmogorov probabilities is not valid. This suggests that a more general (than Kolmogorov) probability theory is needed, and here we adopt the Dempster-Shafer probability theory. In both of these lattices, there are sublattices which are Boolean algebras, and within these 'islands' quantum probabilities are additive.
19

On the assessment of manufacturing systems complexity / Εκτίμηση πολυπλοκότητας συστημάτων παραγωγής

Ευθυμίου, Κωνσταντίνος 12 October 2013 (has links)
Objective of the present study is the development of methods for the assessment of manufacturing systems complexity and the investigation of flexibility and complexity relationship. Towards this target, a complete approach based on information theory permitting the analytical, quantitative and systematic modeling and quantification of both static and dynamic manufacturing complexity is proposed. Static complexity concerns the structure of the manufacturing systems, namely the products, the processes, the resources that constitute the systems as well as their interconnections. Static complexity is treated as the information that is required for the description of a manufacturing system. Multi domain matrices modeling the relationships between products, processes and resources are formalized as networks following the notions of graph theory. The information content of each matrix is assessed employing Shannon entropy measure and their aggregation yields the static complexity. Dynamic complexity is related to the uncertainty in the behaviour of a manufacturing system and in the present study is associated with the unpredictability of the performance indicators timeseries. The unpredictability of the performance indicators timeseries, which are provided by computer simulation, is captured employing the Lempel Ziv algorithm that calculates the Kolmogorov complexity. The dynamic complexity is either the unpredictability of a specific timeseries or the weighted mean of a series of performance indicators timeseries produced under different product demand scenarios. The relationship between flexibility and complexity is investigated for a group of 19 different configurations of a manufacturing system. In particular, operation flexibility that refers to the system’s ability to produce a set of products through different machines, materials, operations and sequences of operations and total complexity, and both static and dynamic are examined employing a utility function. As a case study, two assembly lines producing three car floor model types at three different product mixes are investigated. The dynamic complexity of each assembly line is assessed and the relationship between product mix and dynamic complexity is studied. The evaluation of the case study revealed the efficiency of the suggested approach validated its applicability to industrial environments. / Αντικείμενο της παρούσας διατριβής είναι η ανάπτυξη μεθόδων για την εκτίμηση πολυπλοκότητας συστημάτων παραγωγής και η διερεύνηση της σχέσης ευελιξίας και πολυπλοκότητας. Προς αυτή την κατεύθυνση προτείνεται μια ολοκληρωμένη προσέγγιση βασισμένη στην θεωρία της πληροφορίας που επιτρέπει μια αναλυτική, ποσοτικοποιημένη και συστηματική προτυποποίηση και εκτίμηση τόσο της στατικής όσο και της δυναμικής πολυπλοκότητας των συστημάτων παραγωγής. Η στατική πολυπλοκότητα αφορά την δομή των συστημάτων παραγωγής, και σχετίζεται με τα προϊόντα, τις διεργασίες, τους παραγωγικούς πόρους που αποτελούν το σύστημα καθώς και τις μεταξύ τους σχέσεις. Η στατική πολυπλοκότητα αντιμετωπίζεται ως η πληροφορία που απαιτείται για να περιγραφεί ένα σύστημα παραγωγής. Πολυ-πεδιακοί πίνακες αναπαριστούν τις σχέσεις μεταξύ προϊόντων, διεργασιών και πόρων και προτυποποιούνται ως δίκτυα ακολουθώντας την θεωρία γράφων. Το πληροφοριακό περιεχόμενο κάθε πίνακα εκτιμάται με την χρήση της εντροπίας Shannon και το άθροισμα για όλους τους πίνακες δίνει την στατική πολυπλοκότητα. Η δυναμική πολυπλοκότητα σχετίζεται με την αβεβαιότητα της συμπεριφοράς των συστημάτων παραγωγής και στην παρούσα διατριβή συνδέεται με την απροβλεψιμότητα των χρονοσειρών δεικτών απόδοσης ενός συστήματος. Οι χρονοσειρές των δεικτών απόδοσης προκύπτουν από υπολογιστική προσομοίωση και η απροβλεψιμότητα τους εκτιμάται με των αλγόριθμο Lempel Ziv ο οποίος υπολογίζει την πολυπλοκότητα Kolmogorov. Η δυναμική πολυπλοκότητα είναι η απροβλεψιμότητα είτε μιας συγκεκριμένης χρονοσειράς είτε ο σταθμισμένος μέσος όρος ενός συνόλου χρονοσειρών δεικτών απόδοσης. Η σχέση ευελιξίας – πολυπλοκότητας διερευνάται για 19 διαμορφώσεις ενός συστήματος παραγωγής. Συγκεκριμένα, η ευελιξία λειτουργίας που αναφέρεται στην ικανότητα ενός συστήματος να παράγει ένα σύνολο προϊόντων χρησιμοποιώντας διαφορετικές μηχανές και διεργασίες και πολυπλοκότητα τόσο η στατική όσο και η δυναμική μελετώνται με μια συνάρτηση χρησιμότητας. Ως περίπτωση μελέτης εξετάζονται δύο γραμμές συναρμολόγησης που παράγουν τρία δάπεδα αμαξιού σε τρία μείγματα παραγωγής. Η δυναμική πολυπλοκότητα κάθε γραμμής και η σχέση μείγματος παραγωγής και δυναμικής πολυπλοκότητα μελετώνται. Η αξιολόγηση της περίπτωσης μελέτης αποδεικνύει την αποτελεσματικότητα των προτεινόμενων μεθόδων σε βιομηχανικό περιβάλλον.
20

Stabilité d'inégalités variationnelles et prox-régularité, équations de Kolmogorov périodiques contrôlées / Stability of variational inequalities and prox-regularity, Perdiodic solutions of controlled Kolmogorov equations

Sebbah, Matthieu 02 July 2012 (has links)
Dans une première partie, nous étudions la stabilité des solutions d'une inégalité variationnelle de la forme cône normal perturbé par une fonction. Pour ce faire, nous généralisons la méthode de S. Robinson, basée sur le degré topologique, aux espaces de Hilbert et à une classe de multi-applications non nécessairement convexes, appelées multi-applications prox-régulières.  Dans une deuxième partie, nous étudions des problèmes de contrôle optimal liés à la modélisation de problèmes de bio-procédés, et l'on s'intéresse à des contraintes périodiques sur l'état. Ainsi, nous étendons les résultats d'existence de solutions périodiques des EDOs de Kolmogorov au cadre du contrôle en rajoutant un paramètre contrôlé à ces équations. Ceci nous permet d'étudier par la suite un problème de commande optimale d'un chemostat sous forçage périodique, et d'en déduire la synthèse optimale pour ce problème. / In the first part, we study stability of solutions of a variational inequality of the form normal cone perturbed by a mapping. To do so, we generalize the method introduced by S. Robinson, based on the topological degree, to the general Hilbert setting on the class of non-necessarily convex set-valued mapping, called prox-regular set-valued mapping. In the second part, we study optimal control problems connected to the modelization of bio-processes and we consider periodic constraints on the state variable. We first extend the existence result of periodic solutions of Kolmogorov ODEs to the setting of control by adding a controlled parameter to those ODEs. This allows us to study an optimal control problem modeling a chemostat under a periodic forcing for which we give the optimal synthesis.

Page generated in 0.0392 seconds