Strain detecting with carbon nanotube (CNT) networks is one of the encouraging findings in sensor technologies. Two types of CNT based films are available for strain detection, namely CNT composite films and CNT films. Configurations of the CNT networks in these films can be made into random and aligned distributions. Understanding of fundamental knowledge regarding piezoresistive response in CNT networks in particular of the CNT film is not quite available, and this is the motivation of the present thesis. In this thesis, piezoresistive response of CNT networks under in-plane straining was studies in details first. Based on the stick percolation model, the relation between the density and conductance in CNT networks (with randomly distributed) was established and then the models which describe the relation between the density and piezoresistive sensitivity and the relation between density and piezoresistive linearity, respectively, were developed. After that, fabrication of CNT networks with aligned distributions was studied. Likewise, the models as developed for CNT network with random distributions were developed for ones with aligned distributions. Finally, modeling of the stress transfer between the nanotubes and polymer matrix was studied. This study has led to the following conclusions: (1) piezoresistive response in CNT networks of the CNT film follows the stick percolation model with the critical exponent coefficient (α) in the model being 1.938; (2) it is feasible to fabricate aligned CNT networks of varying densities with the technique which combines the spray deposition and externally applied magnetic field; (3) the configuration of CNT networks, in addition to their density, was a primary factor governing their piezoresistive response; (4) slipping occurs at the interface between the nanotube and polymer matrix when the films are subject to in-plane straining. The contributions of this study are: (1) the knowledge along with a percolation model for piezoresistive response of CNT networks of the CNT film, (2) a fabrication technique to align CNT networks of the CNT film, and (3) the knowledge along with a model for interaction between the CNT and polymer substrate in the CNT film.

Large-scale networks are becoming more prevalent, with applications in healthcare systems, financial networks, social networks, and traffic systems. The detection of normal and abnormal behaviors (signals) in these systems presents a challenging problem. State-of-the-art approaches such as principal component analysis and graph signal processing address this problem using signal projections onto a space determined by an eigendecomposition or singular value decomposition. When a graph is directed, however, applying methods based on the graph Laplacian or singular value decomposition causes information from unidirectional edges to be lost. Here we present a novel formulation and graph signal processing framework that addresses this issue and that is well suited for application to extremely large, directed, sparse networks. In this thesis, we develop and demonstrate a graph Fourier transform for which the spectral components are the Jordan subspaces of the adjacency matrix. In addition to admitting a generalized Parseval’s identity, this transform yields graph equivalence classes that can simplify the computation of the graph Fourier transform over certain networks. Exploration of these equivalence classes provides the intuition for an inexact graph Fourier transform method that dramatically reduces computation time over real-world networks with nontrivial Jordan subspaces. We apply our inexact method to four years of New York City taxi trajectories (61 GB after preprocessing) over the NYC road network (6,400 nodes, 14,000 directed edges). We discuss optimization strategies that reduce the computation time of taxi trajectories from raw data by orders of magnitude: from 3,000 days to less than one day. Our method yields a fine-grained analysis that pinpoints the same locations as the original method while reducing computation time and decreasing energy dispersal among spectral components. This capability to rapidly reduce raw traffic data to meaningful features has important ramifications for city planning and emergency vehicle routing.

Thesis (Ph. D.)--School of Electrical and Computer Engineering, Georgia Institute of Technology, 2004. Directed by Douglas M. Blough. / Includes bibliographical references (leaves 62-63).

Στην διπλωματική εργασία παρουσιάζεται μια νέα δομή δεδομένων ειδικά σχεδιασμένη για δίκτυα μεταφορών ευρείας κλίμακας τα οποία αλλάζουν δυναμικά. Η νέα δομή δεδομένων γραφημάτων μας παρέχει ταυτόχρονα τρία μοναδικά χαρακτηρισ τικά: 1. Σύμπτυξη(Compactness): ικανότητα να προσπελάσει αποδοτικά διαδοχικές κορυφές και ακμές, μια απαίτηση όλων των αλγορίθμων γραφημάτων). 2. Ευκινησία (Agility): ικανότητα να αλλάξει και να ρυθμίσει εξαρχής την εσωτερική της διάταξη με σκοπό να βελτιώσει την τοπικότητα των αναφορών των στοιχείων, σύμφωνα με έναν δεδομένο αλγόριθμο. 3. Δυναμικότητα (Dynamicity): ικανότητα να ενθέσει ή να διαγράψει αποδοτικά κορυφές και ακμές. Όλες οι προηγούμενες γνωστές δομές γραφημάτων δεν υποστήριζαν τουλάχιστον ένα από τα προηγούμενα χαρακτηριστικά ή/και δεν μπορούσαν να εφαρμοστούν σε δυναμικά δίκτυα μεταφορών ευρείας κλίμακας. Σε αυτή τη διπλωματική εργασία, παρουσιάζεται η πρακτικότητα της νέας δομής γραφημάτων εκτελώντας μια εκτενή πειραματική μελέτη για δρομολόγηση συντομότερων διαδρομών σε Ευρωπαϊκά οδικά δίκτυα ευρείας κλίμακας με μερικές δεκάδες εκατομμύρια κορυφές και ακμές. Χρησιμοποιώντας κλασικούς αλγόριθμους εύρεσης συντομότερων διαδρομών, επιτυγχάνονται εύκολα χρόνοι ερωτημάτων από μια αρχική κορυφή σε μια τελική κορυφή της τάξης των milliseconds, ενώ η νέα δομή γραφημάτων μας μπορεί να ενημερωθεί σε μόλις μερικά microseconds μετά από μια ένθεση ή διαγραφή μιας κορυφής ή ακμής. / We present a new graph data structure specifically suited for large scale transportation networks in dynamic scenario. Our graph data structure provides tree unique characteristics, namely compactness, agility and dynamicity. All previous data structures were lacking support in at least one of the aforementioned characteristics. We demonstrate the practicality of the new graph data structure by conducting experiments on large scale European road networks, achieving query times of classical routing algorithms in the order of milliseconds and update times in the order of a few microseconds.

No description available.

No description available.

No description available.

The objective of the research is to study optimal routing policy (ORP) problems and to develop an optimal adaptive routing algorithm practical for large-scale Stochastic Time-Dependent (STD) real-life networks, where a traveler could revise the route choice based upon en route information. The routing problems studied can be viewed as counterparts of shortest path problems in deterministic networks. A routing policy is defined as a decision rule that specifies what node to take next at each decision node based on realized link travel times and the current time. The existing routing policy algorithm is for explorative purpose and can only be applied to hypothetical simplified network. In this research, important changes have been made to make it practical in a large-scale real-life network. Important changes in the new algorithm include piece-wise linear travel time representation, turn-based, label-correcting, criterion of stochastic links, and dynamic blocked links. Complete dependency perfect online information (CDPI) variant is then studied in a real-life network (Pioneer Valley, Massachusetts). Link travel times are modeled as random variables with time-dependent distributions which are obtained by running Dynamic Traffic Assignment (DTA) using data provided by Pioneer Valley Planning Commission (PVPC). A comprehensive explanation of the changes by comparing the two algorithms and an in-depth discussion of the parameters that affects the runtime of the new algorithm is given. Computational tests on the runtime changing with different parameters are then carried out and the summary of its effectiveness are presented. To further and fully understand the applicability and efficiency, this algorithm is then tested in another large-scale network, Stockholm in Sweden, and in small random networks. This research is also a good starting point to investigate strategic route choice models and strategic route choice behavior in a real-life network. The major tasks are to acquire data, generate time-adaptive routing policies, and estimate the runtime of the algorithm by changing the parameters in two large-scale real-life networks, and to test the algorithm in small random networks. The research contributes to the knowledge base of ORP problems in stochastic time-dependent (STD) networks by developing an algorithm practical for large-scale networks that considers complete time-wise and link-wise stochastic dependency.

Selecionamos para análise nesta dissertação os Choros nº4 (1926) e Choros nº7 (1924), obras de câmara compostas por Heitor Villa-Lobos (1887-1959) no período em que o compositor demonstrou grande interesse pela estética modernista que hoje chamamos \"pós-tonal\". Villa-Lobos mesclou em seus Choros - bem como em grande parte de sua obra - elementos do modernismo europeu com outros oriundos da cultura popular brasileira, neste caso em particular o choro urbano carioca das primeiras décadas do século XX. Em síntese, a linguagem utilizada por Villa-Lobos nos dois Choros se aproxima muito da técnica de composição \"em camadas\" recorrente em obras de Stravinsky como A Sagração da Primavera (1913), Petrushka (1911) e O pássaro de fogo (1910). Villa-Lobos utiliza a interação entre materiais harmônicos independentes (estruturas simples geradas individualmente e calcadas em escalas tradicionais não gerenciadas pela tonalidade herdada do classicismo). Em muitos momentos esses materiais escalares estão empilhados formando grandes conjuntos (supercoleções) com oito, nove, dez, onze classes de altura e até o conjunto cromático completo, relacionados por invariâncias entre essas estruturas. Em outras ocasiões esses complexos harmônicos aparecem justapostos, relacionados por transformação intervalar gradativa, operados em torno de classes de altura invariantes e movimentos discretos entre as remanescentes não comuns (prioritariamente por movimentos de tons e semitons), procedimento chamado pelos teóricos da vertente \"neo-Riemanniana\" (como Richard Cohn, Jack Douthett e Peter Steinbach, entre outros) como \"parcimônia\". Notamos também que Villa-Lobos com frequência relaciona essas camadas estratificadas por disposições intervalares simétricas, gerenciando os conjuntos de classes de altura que compõem as partes ou a totalidade harmônica em torno de eixos de simetrias invariantes (reflexão). Notamos ainda invariâncias frequentemente reiteradas em ostinato (simetria por translação), enquanto que variantes remanescentes surgem e desaparecem como segmentos de coleções em outras camadas ao longo do trecho conduzido pelo ostinato, completando a totalidade harmônica por justaposição. A partir desse diagnóstico preliminar, elegemos nesta pesquisa duas correntes analíticas distintas e concomitantes: a simetria intervalar (reflexão e translação) a partir de estudos sobre Teoria dos Conjuntos desenvolvidos essencialmente nos textos de Joseph Straus e João Pedro Oliveira; e a transformação intervalar atuando como regente na relação entre coleções dispostas em rede e na construção de grandes complexos harmônicos (supercoleções), aproximando nossa pesquisa de estudos neo-Riemannianos sobre redes de coleções e parcimônia, em especial os trabalhos desenvolvidos por Dmitri Tymoczko, Richard Cohn, Jack Douthett e Peter Steinbach. / Selected for analysis in this dissertation the Choros No.4 (1926) and Choros No.7 (1924), chamber works for the period of the 1920s, at which time the composer has shown great interest in a tilted to a high content of post- tonal modernist aesthetic harmonic complexity concatenated surface exposure of arguments coming from the Brazilian popular culture, in this particular case referencing the urban carioca choro from the first decades of the twentieth century. In summary, the language used by Villa-Lobos in the two Choros is closely to the composition technique in \'layers\' applied in works such as Stravinsky\'s Rite of Spring (1913), Petrushka (1911) and The Firebird (1910). Villa-Lobos uses the interaction between independent harmonic materials (simple structures generated individually with traditional scales not managed by the tonality inherited of classicism). In many instances these scales are stacked forming large sets (supersets) with eight, nine, ten, eleven pitch-classes or the complete chromatic; structures related by invariances. At other times these harmonic complexes appear juxtaposed, related by gradual intervallic transformations, operated around invariants pitch-class sets and discrete movements between remaining pitch-classes not common (primarily by movements of tones and semitones), a procedure called by the theorists of the \'neo-Riemannian\' (as Richard Cohn, Jack Douthett & Peter Steinbach and others) as \'parsimony\'. We also noticed that Villa-Lobos often relates these stratified layers by symmetrical intervallic arrangements, managing pitch-class sets that make up the parts or whole harmonic around axes of symmetry invariants (reflection). We also noted invariances often repeated on ostinato (translational symmetry), while remnants variants arise and disappear as segments of scales into different layers along the stretch led by ostinato, completing the entirety harmonious by juxtaposition. From this preliminary diagnosis, we choose in this research two distinct and concurrent analytical currents: the intervallic symmetry (invertional and translational) from studies on Pitch-Class Set Theory developed mainly in the writings of Joseph Straus and João Pedro Oliveira; and the intervallic transformation working as conductor in the relationship between scales arranged in network and in building of large harmonics sets (supersets), approaching our research to neo-Riemannian studies about scale networks and parsimony, in particular the texts by Dmitri Tymoczko, Richard Cohn, Jack Douthett & Peter Steinbach.

Selecionamos para análise nesta dissertação os Choros nº4 (1926) e Choros nº7 (1924), obras de câmara compostas por Heitor Villa-Lobos (1887-1959) no período em que o compositor demonstrou grande interesse pela estética modernista que hoje chamamos \"pós-tonal\". Villa-Lobos mesclou em seus Choros - bem como em grande parte de sua obra - elementos do modernismo europeu com outros oriundos da cultura popular brasileira, neste caso em particular o choro urbano carioca das primeiras décadas do século XX. Em síntese, a linguagem utilizada por Villa-Lobos nos dois Choros se aproxima muito da técnica de composição \"em camadas\" recorrente em obras de Stravinsky como A Sagração da Primavera (1913), Petrushka (1911) e O pássaro de fogo (1910). Villa-Lobos utiliza a interação entre materiais harmônicos independentes (estruturas simples geradas individualmente e calcadas em escalas tradicionais não gerenciadas pela tonalidade herdada do classicismo). Em muitos momentos esses materiais escalares estão empilhados formando grandes conjuntos (supercoleções) com oito, nove, dez, onze classes de altura e até o conjunto cromático completo, relacionados por invariâncias entre essas estruturas. Em outras ocasiões esses complexos harmônicos aparecem justapostos, relacionados por transformação intervalar gradativa, operados em torno de classes de altura invariantes e movimentos discretos entre as remanescentes não comuns (prioritariamente por movimentos de tons e semitons), procedimento chamado pelos teóricos da vertente \"neo-Riemanniana\" (como Richard Cohn, Jack Douthett e Peter Steinbach, entre outros) como \"parcimônia\". Notamos também que Villa-Lobos com frequência relaciona essas camadas estratificadas por disposições intervalares simétricas, gerenciando os conjuntos de classes de altura que compõem as partes ou a totalidade harmônica em torno de eixos de simetrias invariantes (reflexão). Notamos ainda invariâncias frequentemente reiteradas em ostinato (simetria por translação), enquanto que variantes remanescentes surgem e desaparecem como segmentos de coleções em outras camadas ao longo do trecho conduzido pelo ostinato, completando a totalidade harmônica por justaposição. A partir desse diagnóstico preliminar, elegemos nesta pesquisa duas correntes analíticas distintas e concomitantes: a simetria intervalar (reflexão e translação) a partir de estudos sobre Teoria dos Conjuntos desenvolvidos essencialmente nos textos de Joseph Straus e João Pedro Oliveira; e a transformação intervalar atuando como regente na relação entre coleções dispostas em rede e na construção de grandes complexos harmônicos (supercoleções), aproximando nossa pesquisa de estudos neo-Riemannianos sobre redes de coleções e parcimônia, em especial os trabalhos desenvolvidos por Dmitri Tymoczko, Richard Cohn, Jack Douthett e Peter Steinbach. / Selected for analysis in this dissertation the Choros No.4 (1926) and Choros No.7 (1924), chamber works for the period of the 1920s, at which time the composer has shown great interest in a tilted to a high content of post- tonal modernist aesthetic harmonic complexity concatenated surface exposure of arguments coming from the Brazilian popular culture, in this particular case referencing the urban carioca choro from the first decades of the twentieth century. In summary, the language used by Villa-Lobos in the two Choros is closely to the composition technique in \'layers\' applied in works such as Stravinsky\'s Rite of Spring (1913), Petrushka (1911) and The Firebird (1910). Villa-Lobos uses the interaction between independent harmonic materials (simple structures generated individually with traditional scales not managed by the tonality inherited of classicism). In many instances these scales are stacked forming large sets (supersets) with eight, nine, ten, eleven pitch-classes or the complete chromatic; structures related by invariances. At other times these harmonic complexes appear juxtaposed, related by gradual intervallic transformations, operated around invariants pitch-class sets and discrete movements between remaining pitch-classes not common (primarily by movements of tones and semitones), a procedure called by the theorists of the \'neo-Riemannian\' (as Richard Cohn, Jack Douthett & Peter Steinbach and others) as \'parsimony\'. We also noticed that Villa-Lobos often relates these stratified layers by symmetrical intervallic arrangements, managing pitch-class sets that make up the parts or whole harmonic around axes of symmetry invariants (reflection). We also noted invariances often repeated on ostinato (translational symmetry), while remnants variants arise and disappear as segments of scales into different layers along the stretch led by ostinato, completing the entirety harmonious by juxtaposition. From this preliminary diagnosis, we choose in this research two distinct and concurrent analytical currents: the intervallic symmetry (invertional and translational) from studies on Pitch-Class Set Theory developed mainly in the writings of Joseph Straus and João Pedro Oliveira; and the intervallic transformation working as conductor in the relationship between scales arranged in network and in building of large harmonics sets (supersets), approaching our research to neo-Riemannian studies about scale networks and parsimony, in particular the texts by Dmitri Tymoczko, Richard Cohn, Jack Douthett & Peter Steinbach.