Dissertations / Theses on the topic 'Frequent pattern analysis'
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Pragarauskaitė, Julija. "Frequent pattern analysis for decision making in big data." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2013. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2013~D_20130701_092451-80961.
Full textAbstract:
Huge amounts of digital information are stored in the World today and the amount is increasing by quintillion bytes every day. Approximate data mining algorithms are very important to efficiently deal with such amounts of data due to the computation speed required by various real-world applications, whereas exact data mining methods tend to be slow and are best employed where the precise results are of the highest important.
This thesis focuses on several data mining tasks related to analysis of big data: frequent pattern mining and visual representation.
For mining frequent patterns in big data, three novel approximate methods are proposed and evaluated on real and artificial databases:
• Random Sampling Method (RSM) creates a random sample from the original database and makes assumptions on the frequent and rare sequences based on the analysis results of the random sample. A significant benefit is a theoretical estimate of classification errors made by this method using standard statistical methods.
• Multiple Re-sampling Method (MRM) is an improved version of RSM method with a re-sampling strategy that decreases the probability to incorrectly classify the sequences as frequent or rare.
• Markov Property Based Method (MPBM) relies upon the Markov property. MPBM requires reading the original database several times (the number equals to the order of the Markov process) and then calculates the empirical frequencies using the Markov property.
For visual representation... [to full text]Didžiuliai informacijos kiekiai yra sukaupiami kiekvieną dieną pasaulyje bei jie sparčiai auga. Apytiksliai duomenų tyrybos algoritmai yra labai svarbūs analizuojant tokius didelius duomenų kiekius, nes algoritmų greitis yra ypač svarbus daugelyje sričių, tuo tarpu tikslieji metodai paprastai yra lėti bei naudojami tik uždaviniuose, kuriuose reikalingas tikslus atsakymas. Ši disertacija analizuoja kelias duomenų tyrybos sritis: dažnų sekų paiešką bei vizualizaciją sprendimų priėmimui. Dažnų sekų paieškai buvo pasiūlyti trys nauji apytiksliai metodai, kurie buvo testuojami naudojant tikras bei dirbtinai sugeneruotas duomenų bazes: • Atsitiktinės imties metodas (Random Sampling Method - RSM) formuoja pradinės duomenų bazės atsitiktinę imtį ir nustato dažnas sekas, remiantis atsitiktinės imties analizės rezultatais. Šio metodo privalumas yra teorinis paklaidų tikimybių įvertinimas, naudojantis standartiniais statistiniais metodais. • Daugybinio perskaičiavimo metodas (Multiple Re-sampling Method - MRM) yra RSM metodo patobulinimas, kuris formuoja kelias pradinės duomenų bazės atsitiktines imtis ir taip sumažina paklaidų tikimybes. • Markovo savybe besiremiantis metodas (Markov Property Based Method - MPBM) kelis kartus skaito pradinę duomenų bazę, priklausomai nuo Markovo proceso eilės, bei apskaičiuoja empirinius dažnius remdamasis Markovo savybe. Didelio duomenų kiekio vizualizavimui buvo naudojami pirkėjų internetu elgsenos duomenys, kurie analizuojami naudojant... [toliau žr. visą tekstą]
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Nunna, Shinjini. "Using Association Analysis for Medical Diagnoses." Scholarship @ Claremont, 2016. http://scholarship.claremont.edu/scripps_theses/808.
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In order to fully examine the application of association analysis to medical data for the purpose of deriving medical diagnoses, we survey classical association analysis and approaches, the current challenges faced by medical association analysis and proposed solutions, and finally culminate this knowledge in a proposition for the application of medical association analysis to the identification of food intolerance. The field of classical association analysis has been well studied since its introduction in the seminal paper on market basket research in the 1990's. While the theory itself is relatively simple, the brute force approach is prohibitively expensive and thus, creative approaches utilizing various data structures and strategies must be explored for efficiency. Medical association analysis is a burgeoning field with various focuses, including diagnosis systems and gene analysis. There are a number of challenges faced in the field, primarily stemming from characteristics of analysis of complex, voluminous and high dimensional medical data. We examine the challenges faced in the pre-processing, analysis and post-processing phases, and corresponding solutions. Additionally, we survey proposed measures for ensuring the results of medical association analysis will hold up to medical diagnosis standards. Finally, we explore how medical association analysis can be utilized to identify food intolerances. The proposed analysis system is based upon a current method of diagnosis used by medical professionals, and seeks to eliminate manual analysis, while more efficiently and intelligently identifying interesting, and less obvious patterns between patients' food consumption and symptoms to propose a food intolerance diagnosis.
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Almuhisen, Feda. "Leveraging formal concept analysis and pattern mining for moving object trajectory analysis." Thesis, Aix-Marseille, 2018. http://www.theses.fr/2018AIXM0738/document.
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Cette thèse présente un cadre de travail d'analyse de trajectoires contenant une phase de prétraitement et un processus d’extraction de trajectoires d’objets mobiles. Le cadre offre des fonctions visuelles reflétant le comportement d'évolution des motifs de trajectoires. L'originalité de l’approche est d’allier extraction de motifs fréquents, extraction de motifs émergents et analyse formelle de concepts pour analyser les trajectoires. A partir des données de trajectoires, les méthodes proposées détectent et caractérisent les comportements d'évolution des motifs. Trois contributions sont proposées : Une méthode d'analyse des trajectoires, basée sur les concepts formels fréquents, est utilisée pour détecter les différents comportements d’évolution de trajectoires dans le temps. Ces comportements sont “latents”, "emerging", "decreasing", "lost" et "jumping". Ils caractérisent la dynamique de la mobilité par rapport à l'espace urbain et le temps. Les comportements détectés sont visualisés sur des cartes générées automatiquement à différents niveaux spatio-temporels pour affiner l'analyse de la mobilité dans une zone donnée de la ville. Une deuxième méthode basée sur l'extraction de concepts formels séquentiels fréquents a également été proposée pour exploiter la direction des mouvements dans la détection de l'évolution. Enfin, une méthode de prédiction basée sur les chaînes de Markov est présentée pour prévoir le comportement d’évolution dans la future période pour une région. Ces trois méthodes sont évaluées sur ensembles de données réelles . Les résultats expérimentaux obtenus sur ces données valident la pertinence de la proposition et l'utilité des cartes produitesThis dissertation presents a trajectory analysis framework, which includes both a preprocessing phase and trajectory mining process. Furthermore, the framework offers visual functions that reflect trajectory patterns evolution behavior. The originality of the mining process is to leverage frequent emergent pattern mining and formal concept analysis for moving objects trajectories. These methods detect and characterize pattern evolution behaviors bound to time in trajectory data. Three contributions are proposed: (1) a method for analyzing trajectories based on frequent formal concepts is used to detect different trajectory patterns evolution over time. These behaviors are "latent", "emerging", "decreasing", "lost" and "jumping". They characterize the dynamics of mobility related to urban spaces and time. The detected behaviors are automatically visualized on generated maps with different spatio-temporal levels to refine the analysis of mobility in a given area of the city, (2) a second trajectory analysis framework that is based on sequential concept lattice extraction is also proposed to exploit the movement direction in the evolution detection process, and (3) prediction method based on Markov chain is presented to predict the evolution behavior in the future period for a region. These three methods are evaluated on two real-world datasets. The obtained experimental results from these data show the relevance of the proposal and the utility of the generated maps
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Pragarauskaitė, Julija. "Dažnų sekų analizė sprendimų priėmimui labai didelėse duomenų bazėse." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2013. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2013~D_20130701_092337-79289.
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Didžiuliai informacijos kiekiai yra sukaupiami kiekvieną dieną pasaulyje bei jie sparčiai auga. Apytiksliai duomenų tyrybos algoritmai yra labai svarbūs analizuojant tokius didelius duomenų kiekius, nes algoritmų greitis yra ypač svarbus daugelyje sričių, tuo tarpu tikslieji metodai paprastai yra lėti bei naudojami tik uždaviniuose, kuriuose reikalingas tikslus atsakymas.
Ši disertacija analizuoja kelias duomenų tyrybos sritis: dažnų sekų paiešką bei vizualizaciją sprendimų priėmimui.
Dažnų sekų paieškai buvo pasiūlyti trys nauji apytiksliai metodai, kurie buvo testuojami naudojant tikras bei dirbtinai sugeneruotas duomenų bazes:
• Atsitiktinės imties metodas (Random Sampling Method - RSM) formuoja pradinės duomenų bazės atsitiktinę imtį ir nustato dažnas sekas, remiantis atsitiktinės imties analizės rezultatais. Šio metodo privalumas yra teorinis paklaidų tikimybių įvertinimas, naudojantis standartiniais statistiniais metodais.
• Daugybinio perskaičiavimo metodas (Multiple Re-sampling Method - MRM) yra RSM metodo patobulinimas, kuris formuoja kelias pradinės duomenų bazės atsitiktines imtis ir taip sumažina paklaidų tikimybes.
• Markovo savybe besiremiantis metodas (Markov Property Based Method - MPBM) kelis kartus skaito pradinę duomenų bazę, priklausomai nuo Markovo proceso eilės, bei apskaičiuoja empirinius dažnius remdamasis Markovo savybe.
Didelio duomenų kiekio vizualizavimui buvo naudojami pirkėjų internetu elgsenos duomenys, kurie analizuojami naudojant... [toliau žr. visą tekstą]Huge amounts of digital information are stored in the World today and the amount is increasing by quintillion bytes every day. Approximate data mining algorithms are very important to efficiently deal with such amounts of data due to the computation speed required by various real-world applications, whereas exact data mining methods tend to be slow and are best employed where the precise results are of the highest important. This thesis focuses on several data mining tasks related to analysis of big data: frequent pattern mining and visual representation. For mining frequent patterns in big data, three novel approximate methods are proposed and evaluated on real and artificial databases: • Random Sampling Method (RSM) creates a random sample from the original database and makes assumptions on the frequent and rare sequences based on the analysis results of the random sample. A significant benefit is a theoretical estimate of classification errors made by this method using standard statistical methods. • Multiple Re-sampling Method (MRM) is an improved version of RSM method with a re-sampling strategy that decreases the probability to incorrectly classify the sequences as frequent or rare. • Markov Property Based Method (MPBM) relies upon the Markov property. MPBM requires reading the original database several times (the number equals to the order of the Markov process) and then calculates the empirical frequencies using the Markov property. For visual representation... [to full text]
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Wang, Chao. "Exploiting non-redundant local patterns and probabilistic models for analyzing structured and semi-structured data." Columbus, Ohio : Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1199284713.
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Singh, Shailendra. "Smart Meters Big Data : Behavioral Analytics via Incremental Data Mining and Visualization." Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/35244.
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The big data framework applied to smart meters offers an exception platform for data-driven forecasting and decision making to achieve sustainable energy efficiency. Buying-in consumer confidence through respecting occupants' energy consumption behavior and preferences towards improved participation in various energy programs is imperative but difficult to obtain. The key elements for understanding and predicting household energy consumption are activities occupants perform, appliances and the times that appliances are used, and inter-appliance dependencies. This information can be extracted from the context rich big data from smart meters, although this is challenging because: (1) it is not trivial to mine complex interdependencies between appliances from multiple concurrent data streams; (2) it is difficult to derive accurate relationships between interval based events, where multiple appliance usage persist; (3) continuous generation of the energy consumption data can trigger changes in appliance associations with time and appliances. To overcome these challenges, we propose an unsupervised progressive incremental data mining technique using frequent pattern mining (appliance-appliance associations) and cluster analysis (appliance-time associations) coupled with a Bayesian network based prediction model. The proposed technique addresses the need to analyze temporal energy consumption patterns at the appliance level, which directly reflect consumers' behaviors and provide a basis for generalizing household energy models. Extensive experiments were performed on the model with real-world datasets and strong associations were discovered. The accuracy of the proposed model for predicting multiple appliances usage outperformed support vector machine during every stage while attaining accuracy of 81.65\%, 85.90\%, 89.58\% for 25\%, 50\% and 75\% of the training dataset size respectively. Moreover, accuracy results of 81.89\%, 75.88\%, 79.23\%, 74.74\%, and 72.81\% were obtained for short-term (hours), and long-term (day, week, month, and season) energy consumption forecasts, respectively.
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MATOS, MARCILIO CASTRO DE. "SEISMIC PATTERN RECOGNITION USING TIME-FREQUENCY ANALYSES." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2004. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=5081@1.
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INSTITUTO MILITAR DE ENGENHARIAIndependente da metodologia adotada para realizar análise de fácies sísmicas, a segmentação temporal e espacial da região do reservatório deve ser realizada cuidadosamente. A confiança no resultado da interpretação depende da complexidade do sistema geológico, da qualidade dos dados sísmicos, e da experiência do intérprete. Portanto, qualquer erro de interpretação pode levar a resultados incoerentes. Especialmente, a análise de fácies sísmicas utilizando formas de onda do sinal na região do reservatório é bastante sensível a ruídos de interpretação. Sabe-se que variações no conteúdo de freqüência dos traços sísmicos podem estar associadas às informações de refletividade da sub-superfície. Conseqüentemente, análises conjuntas em tempo - freqüência podem levar a formas não convencionais para a caracterização de reservatórios. Especificamente, esta tese propõe o uso das propriedades em tempo - freqüência, obtidas através do algoritmo de matching pursuit, e das singularidades detectadas e caracterizadas via transformada wavelet, como ferramenta para detecção de eventos sísmicos e para análise não supervisionada de fácies sísmicas quando associadas ao agrupamento dos mapas auto organizáveis de Kohonen.
Independent of the adopted methodology to perform the seismic facies analysis, the geological oriented spatial and temporal segmentation of the reservoir region should be carefully done. Depending on the complexity of the reservoir system, seismic data quality, and the experience of the interpreter, the level of confidence in an interpretation can vary from very high to very low. Therefore, any interpretation error could lead to wrong or noisy results. Specially, when using seismic trace shapes, defined by the values of the seismic samples along each segmented trace, as the seismic input attributes to the chosen seismic facies algorithm. These facies analysis artifacts are introduced because seismic waveform in the reservoir delimited area changes quickly as a function of the interpretation, then waveforms with almost the same shape could be assigned to different classes due only to their different phases. It is known that variations of the frequency content of a seismic trace with time carry information about the properties of the subsurface reflectivity sequence. Consequently, seismic trace time- frequency analyses could provide an unconventional way to reservoir characterization. Specifically, in this work we propose to use the time-frequency properties of the atoms obtained after the matching pursuit signal representation and the singularities identified by wavelet transform, jointly with Self Organizing Maps as an unsupervised seismic facies analyses system.
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IBARAKI, Toshihide, Endre BOROS, Mutsunori YAGIURA, and Kazuya HARAGUCHI. "A Randomness Based Analysis on the Data Size Needed for Removing Deceptive Patterns." Institute of Electronics, Information and Communication Engineers, 2008. http://hdl.handle.net/2237/15011.
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Wang, Joshua Kevin. "Identification, Analysis, and Control of Power System Events Using Wide-Area Frequency Measurements." Diss., Virginia Tech, 2009. http://hdl.handle.net/10919/26250.
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The power system has long been operated in a shroud of introspection. Only recently have dynamic, wide-area time synchronized grid measurements brought to light the complex relationships between large machines thousands of miles apart. These measurements are invaluable to understanding the health of the system in real time, for disturbances to the balance between generation and load are manifest in the propagation of electromechanical waves throughout the grid. The global perspective of wide-area measurements provides a platform from which the destructive effects of these disturbances can be avoided. Virginia Tech's distributed network of low voltage frequency monitors, FNET, is able to track these waves as they travel throughout the North American interconnected grids. In contrast to other wide-area measurement systems, the ability to easily measure frequency throughout the grid provides a way to identify, locate, and analyze disturbances with high dynamic accuracy. The unique statistical properties of wide-area measurements require robust tools in order to accurately understand the nature of these events. Expert systems and data conditioning can then be used to quantify the magnitude and location of these disturbances without requiring any knowledge of the system state or topology. Adaptive application of these robust methods form the basis for real-time situational awareness and control. While automated control of the power system rarely utilize wide-area measurements, global insight into grid behavior can only improve disturbance rejection.Ph. D.
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FURUHASHI, Takeshi, Tomohiro YOSHIKAWA, Makoto SUZUKI, 武. 古橋, 大弘 吉川, and 誠. 鈴木. "コレスポンデンス分析を用いた文書検索に関する検討." 日本感性工学会, 2013. http://hdl.handle.net/2237/20711.
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Zhong, Shiyin. "Electricity Load Modeling in Frequency Domain." Diss., Virginia Tech, 2017. http://hdl.handle.net/10919/75109.
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In today's highly competitive and deregulated electricity market, companies in the generation, transmission and distribution sectors can all benefit from collecting, analyzing and deep-understanding their customers' load profiles. This strategic information is vital in load forecasting, demand-side management planning and long-term resource and capital planning.
With the proliferation of Advanced Metering Infrastructure (AMI) in recent years, the amount of load profile data collected by utilities has grown exponentially. Such high-resolution datasets are difficult to model and analyze due to the large size, diverse usage patterns, and the embedded noisy or erroneous data points. In order to overcome these challenges and to make the load data useful in system analysis, this dissertation introduces a frequency domain load profile modeling framework. This framework can be used a complementary technology alongside of the conventional time domain load profile modeling techniques.
There are three main components in this framework: 1) the frequency domain load profile descriptor, which is a compact, modular and extendable representation of the original load profile. A methodology was introduced to demonstrate the construction of the frequency domain load profile descriptor. 2) The load profile Characteristic Attributes in the Frequency Domain (CAFD). Which is developed for load profile characterization and classification. 3) The frequency domain load profile statistics and forecasting models. Two different models were introduced in this dissertation: the first one is the wavelet load forecast model and the other one is a stochastic model that incorporates local weather condition and frequency domain load profile statistics to perform medium term load profile forecast.
7 different utilities load profile data were used in this research to demonstrate the viability of modeling load in the frequency domain. The data comes from various customer classes and geographical regions. The results have shown that the proposed framework is capable to model the load efficiently and accurately.Ph. D.
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Facciotto, Nicolò. "Source differentiation and identification of acoustic emission signals by time-frequency analysis." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017.
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In the context of Structural Health Monitoring, the Acoustic Emission Technique may be efficiently used to detect damage on aerospace structures. This study focuses on the development of a source identification algorithm to distinguish different acoustic emission events in aluminium sheets, which have been collected during experimental tests. The future goal will be the design of a Holistic Structural Health Monitoring System which will make the complete aircraft an intelligent structure able to diagnose its own structural damage based on the condition of the structure while maintaining safety.
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Dorai-Raj, Sundardas Samuel. "First- and Second-Order Properties of Spatiotemporal Point Patterns in the Space-Time and Frequency Domains." Diss., Virginia Tech, 2001. http://hdl.handle.net/10919/28540.
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Point processes are common in many physical applications found in engineering and biology.
These processes can be observed in one-dimension as a time series or two-dimensions as a spatial point pattern with extensive amounts of literature devoted to their analyses.
However, if the observed process is a hybrid of spatial and temporal point process, very few practical methods exist.
In such cases, practitioners often remove the temporal component and analyze the spatial dependencies.
This marginal spatial analysis may lead to misleading results if time is an important factor in the process.
In this dissertation we extend the current analysis of spatial point patterns to include a temporal dimension.
First- and second-order intensity measures for analyzing spatiotemporal point patterns are explicitly defined.
Estimation of first-order intensities are examined using 3-dimensional smoothing techniques.
Conditions for weak stationarity are provided so that subsequent second-order analysis can be conducted.
We consider second-order analysis of spatiotemporal point patterns first in the space-time domain through an extension of Ripley's $K$-function.
An alternative analysis is given in the frequency domain though construction of a spatiotemporal periodogram.
The methodology provided is tested through simulation of spatiotemporal point patterns and by analysis of a real data set.
The biological application concerns the estimation of the homerange of groups of the endangered red-cockaded woodpecker in the Fort Bragg area of North Carolina.
Monthly or bimonthly point patterns of the bird distribution are analyzed and integrated over a 23 month period.Ph. D.
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Pethiyagoda, Ravindra. "Mathematical and computational analysis of Kelvin ship wave patterns." Thesis, Queensland University of Technology, 2016. https://eprints.qut.edu.au/101167/1/Ravindra_Pethiyagoda_Thesis.pdf.
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This thesis concerns the form of water wave patterns generated by an idealised ship moving steadily through still water. An efficient numerical scheme for computing these waves with much finer detail than ever before is developed, and the results are used to determine the effect that certain properties, such as the ship's speed and dimensions, have on ship wakes. Two features are used to characterise the ship wave: the ship's apparent wake angle, the half-angle of the characteristic v-pattern of a ship wave, and a spectrogram produced by applying time-frequency analysis to a cross-section of the ship wave.
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Shin, Yoon Shik. "Modifications to a two-control-volume, frequency dependent, transfer-function analysis of hole-pattern gas annular seals." Thesis, Texas A&M University, 2005. http://hdl.handle.net/1969.1/4751.
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A rotordynamic analysis of hole-pattern gas annular seals using a two-control-volume model, Ha and Childs and frequency dependent transfer-function model, Kleynhans and Childs is modified with four features. The energy equation is added, and real gas properties are used instead of the ideal gas equation of state. The depth of the hole-pattern is made variable with the axial distance along the seal. And last, the addition of deep grooves to hole-pattern seals is analyzed, and the codeâÂÂs predictions for the influence of a groove are compared with test data.
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Eklund, Robert. "A Probabilistic Tagging Module Based on Surface Pattern Matching." Thesis, Stockholm University, Department of Computational Linguistics, Institute of Linguistics, 1993. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-135294.
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A problem with automatic tagging and lexical analysis is that it is never 100 % accurate. In order to arrive at better figures, one needs to study the character of what is left untagged by automatic taggers. In this paper untagged residue outputted by the automatic analyser SWETWOL (Karlsson 1992) at Helsinki is studied. SWETWOL assigns tags to words in Swedish texts mainly through dictionary lookup. The contents of the untagged residue files are described and discussed, and possible ways of solving different problems are proposed. One method of tagging residual output is proposed and implemented: the left-stripping method, through which untagged words are bereaved their left-most letters, searched in a dictionary, and if found, tagged according to the information found in the said dictionary. If the stripped word is not found in the dictionary, a match is searched in ending lexica containing statistical information about word classes associated with that particular word form (i.e., final letter cluster, be this a grammatical suffix or not), and the relative frequency of each word class. If a match is found, the word is given graduated tagging according to the statistical information in the ending lexicon. If a match is not found, the word is stripped of what is now its left-most letter and is recursively searched in a dictionary and ending lexica (in that order). The ending lexica employed in this paper are retrieved from a reversed version of Nusvensk Frekvensordbok (Allén 1970), and contain endings of between one and seven letters. The contents of the ending lexica are to a certain degree described and discussed. The programs working according to the principles described are run on files of untagged residual output. Appendices include, among other things, LISP source code, untagged and tagged files, the ending lexica containing one and two letter endings and excerpts from ending lexica containing three to seven letters.
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Otto, Andreas. "Frequency domain methods for the analysis of time delay systems." Doctoral thesis, Universitätsbibliothek Chemnitz, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-208749.
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In this thesis a new frequency domain approach for the analysis of time delay systems is presented. After linearization of a nonlinear delay differential equation (DDE) with constant distributed delay around a constant or periodic reference solution the so-called Hill-Floquet method can be used for the analysis of the resulting linear DDE. In addition, systems with fast or slowly time-varying delays, systems with variable transport delays originating from a transport with variable velocity, and the corresponding spatially extended systems are presented, which can be also analyzed with the presented method. The newly introduced Hill-Floquet method is based on the Hill’s infinite determinant method and enables the transformation of a system with periodic coefficients to an autonomous system with constant coefficients. This makes the usage of a variety of existing methods for autonomous systems available for the analysis of periodic systems, which implies that the typical calculation of the monodromy matrix for the time evolution of the solution over the principle period is no longer required. In this thesis, the Chebyshev collocation method is used for the analysis of the autonomous systems. Specifically, in this case the periodic part of the solution is expanded in a Fourier series and the exponential behavior of the solution is approximated by the discrete values of the Fourier coefficients at the Chebyshev nodes, whereas in classical spectral or pseudo-spectral methods for the analysis of linear periodic DDEs the complete solution is expanded in terms of basis functions. In the last part of this thesis, new results for three applications with time delay effects are presented, which were analyzed with the presented methods. On the one hand, the occurrence of diffusion-driven instabilities in reaction-diffusion systems with delay is investigated. It is shown that wave instabilities are possible already for single-species reaction diffusion systems with distributed or time-varying delay. On the other hand, the stability of metal cutting vibrations at machine tools is analyzed. In particular, parallel orthogonal turning processes with multiple discrete delays and turning processes with a time-varying delay due to a spindle speed variation are studied. Finally, the stability of the synchronized solution in networks with heterogeneous coupling delays is studied. In particular, the eigenmode expansion for synchronized periodic orbits is derived, which includes an extension of the classical master stability function to networks with heterogeneous coupling delays. Numerical results are shown for a network of Hodgkin-Huxley neurons with two delays in the couplingIn dieser Dissertation wird ein neues Verfahren zur Analyse von Systemen mit Totzeiten im Frequenzraum vorgestellt. Nach Linearisierung einer nichtlinearen retardierten Differentialgleichung (DDE) mit konstanter verteilter Totzeit um eine konstante oder periodische Referenzlösung kann die sogenannte Hill-Floquet Methode für die Analyse der resultierende linearen DDE angewendet werden. Darüber hinaus werden Systeme mit schnell oder langsam variierender Totzeit, Systeme mit einer variablen Totzeit, resultierend aus einem Transport mit variabler Geschwindigkeit, und entsprechende räumlich ausgedehnte Systeme vorgestellt, welche ebenfalls mit der vorgestellten Methode analysiert werden können. Die neu eingeführte Hill-Floquet Methode basiert auf der Hillschen unendlichen Determinante und ermöglicht die Transformation eines Systems mit periodischen Koeffizienten auf ein autonomes System mit konstanten Koeffizienten. Dadurch können zur Analyse periodischer Systeme auch eine Vielzahl existierender Methoden für autonome Systeme genutzt werden und die Berechnung der Monodromie-Matrix für die Lösung des Systems über eine Periode entfällt. In dieser Arbeit wird zur Analyse des autonomen Systems die Tschebyscheff-Kollokationsmethode verwendet. Im Speziellen wird bei diesem Verfahren der periodische Teil der Lösung in einer Fourierreihe entwickelt und das exponentielle Verhalten durch die Werte der Fourierkoeffizienten an den Tschebyscheff Knoten approximiert, wohingegen bei klassischen spektralen Verfahren die komplette Lösung in bestimmten Basisfunktionen entwickelt wird. Im Anwendungsteil der Arbeit werden neue Ergebnisse für drei Beispielsysteme präsentiert, welche mit den vorgestellten Methoden analysiert wurden. Es wird gezeigt, dass Welleninstabilitäten schon bei Einkomponenten-Reaktionsdiffusionsgleichungen mit verteilter oder variabler Totzeit auftreten können. In einem zweiten Beispiel werden Schwingungen an Werkzeugmaschinen betrachtet, wobei speziell simultane Drehbearbeitungsprozesse und Prozesse mit Drehzahlvariationen genauer untersucht werden. Am Ende wird die Synchronisation in Netzwerken mit heterogenen Totzeiten in den Kopplungstermen untersucht, wobei die Zerlegung in Netzwerk-Eigenmoden für synchrone periodische Orbits hergeleitet wird und konkrete numerische Ergebnisse für ein Netzwerk aus Hodgkin-Huxley Neuronen gezeigt werden
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Rodgers, Melanie. "Unusual Patterns of Seismicity during Eruptive and Non-eruptive Periods at the Persistently Restless Telica Volcano, Nicaragua." Scholar Commons, 2013. http://scholarcommons.usf.edu/etd/4934.
Full textAbstract:
Telica Volcano, Nicaragua, is a persistently restless volcano with high rates of seismicity that can vary from less than ten events to over a thousand events per day. Low-frequency (LF) events dominate the seismic catalogue and seismicity rates at Telica show little clear correlation with periods of eruption. As such, traditional methods of forecasting of volcanic activity based on increases in seismicity and recognition of LF activity are not applicable. A single seismic station has been operating at Telica since 1993, and in 2010 we installed a broadband seismic and continuous GPS network (TESAND network) at Telica. In this study we investigate the seismic characteristics surrounding a nine-month period of phreatic to phreatomagmatic explosions in 1999, and also from the initial three-and-a-half year deployment of the TESAND network, including a three-month phreatic vulcanian eruptive period in 2011. We demonstrate that pertinent information can be obtained from analysis of single-station data, and while large seismic networks are preferable when possible, we note that for many volcanoes this is not possible. We find unusual patterns of seismicity before both eruptive periods; rather than a precursory increase in seismicity as is observed prior to many volcanic eruptions, we observe a decrease in seismicity many months prior to eruption. We developed a new program for cross-correlation of large seismic data catalogues and analysed multiplet activity surrounding both eruptive periods. We observed that the formation of new multiplets corresponds to periods of high event rates (during inter-eruptive periods) and high percentages of daily events that belong to a multiplet. We propose a model for the seismicity patterns observed at Telica, where changes in seismicity are related to a cyclic transition between open-system degassing and closed-system degassing. Periods of open-system degassing occur during non-eruptive episodes and are characterised by high event rates, a broad range of frequency content of events and high degrees of waveform correlation. A transition to closed-system degassing could be due to sealing of fluid pathways in the magmatic and/or hydrothermal system, or due to magma withdrawal. Periods of closed-system degassing are characterised by low event rates, higher frequency contents and low degrees of waveform correlation. Eruptive periods may then represent a transition from closed-system degassing to open-system degassing, however the system must also be capable of transitioning to open-system degassing without eruption. These observations have important implications for volcano monitoring and eruption forecasting at persistently restless volcanoes. Rather than a precursory increase in seismicity as is often observed prior to eruption at other volcanoes, our observations indicate that phreatic eruptions at Telica occur after a decrease in seismicity, a corresponding change in the frequency content of events, and a decrease in waveform correlation. These changes may represent a period of closed-system degassing that could culminate in phreatic eruptions. The inclusion of real-time analysis of variations in frequency content and multiplet activity provides critical information for volcano monitoring institutions.
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Vaizurs, Raja Sarath Chandra Prasad. "Atrial Fibrillation Signal Analysis." Scholar Commons, 2011. http://scholarcommons.usf.edu/etd/3386.
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Atrial fibrillation (AF) is the most common type of cardiac arrhythmia encountered in clinical practice and is associated with an increased mortality and morbidity. Identification of the sources of AF has been a goal of researchers for over 20 years. Current treatment procedures such as Cardio version, Radio Frequency Ablation, and multiple drugs have reduced the incidence of AF. Nevertheless, the success rate of these treatments is only 35-40% of the AF patients as they have limited effect in maintaining the patient in normal sinus rhythm. The problem stems from the fact that there are no methods developed to analyze the electrical activity generated by the cardiac cells during AF and to detect the aberrant atrial tissue that triggers it.
In clinical practice, the sources triggering AF are generally expected to be at one of the four pulmonary veins in the left atrium. Classifying the signals originated from four pulmonary veins in left atrium has been the mainstay of signal analysis in this thesis which ultimately leads to correctly locating the source triggering AF. Unlike many of the current researchers where they use ECG signals for AF signal analysis, we collect intra cardiac signals along with ECG signals for AF analysis. AF Signal collected from catheters placed inside the heart gives us a better understanding of AF characteristics compared to the ECG.
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In recent years, mechanisms leading to AF induction have begun to be explored but the current state of research and diagnosis of AF is mainly about the inspection of 12 lead ECG, QRS subtraction methods, spectral analysis to find the fibrillation rate and limited to establishment of its presence or absence. The main goal of this thesis research is to develop methodology and algorithm for finding the source of AF. Pattern recognition techniques were used to classify the AF signals originated from the four pulmonary veins. The classification of AF signals recorded by a stationary intra-cardiac catheter was done based on dominant frequency, frequency distribution and normalized power. Principal Component Analysis was used to reduce the dimensionality and further, Linear Discriminant Analysis was used as a classification technique. An algorithm has been developed and tested during recorded periods of AF with promising results.
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Al, Khambashi Majid S. "Analysis and solutions for RFID tag and RFID reader deployment in wireless communications applications. Simulation and measurement of linear and circular polarised RFID tag and reader antennas and analysing the tags radiation efficiency when operated close to the human body." Thesis, University of Bradford, 2012. http://hdl.handle.net/10454/6340.
Full textAbstract:
The aim of this study is to analysis, investigate and find out the solutions for the
problems associated with the implementations of antennas RFID Reader and Tag
for various applications. In particular, the efficiency of the RFID reader antenna
and the detection range of the RFID tag antenna, subject to a small and compact
antenna¿s design configuration have been studied.
The present work has been addressed directly to reduce the cost, size and increase
the detection range and communication reliability of the RFID framework
antennas. Furthermore, the modelling concept of RFID passive tags mounted on
various materials including the novel design of RFID reader antenna using
Genetic Algorithm (GA) are considered and discussed to maintain reliable and
efficient antenna radiation performances.
The main benefit of applying GA is to provide fast, accurate and reliable solutions
of antenna¿s structure. Therefore, the GA has been successfully employed to
design examples: meander-line, two linear cross elements and compact Helical-
Spiral antennas.
In addition, a hybrid method to model the human body interaction with RFID tag
antenna operating at 900MHz has been studied. The near field distribution and the
radiation pattern together with the statistical distribution of the radiation
efficiency and the absorbed power in terms of cumulative distribution functions
for different orientation and location of RFID¿s tag antenna on the human body
have been demonstrated.
Several tag antennas wi th symmetrical and unsymmetrical structure configurations
operating in the European UHF band 850-950 MHz have been fabricated and
tested. . The measured and simulated results have been found to be in a good
agreement with reasonable impedance matching to the typical input impedance of
an RFID integrated circuit chip and nominal power gain and radiation patterns.
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Al, Khambashi Majid Salim. "Analysis and solutions for RFID tag and RFID reader deployment in wireless communications applications : simulation and measurement of linear and circular polarised RFID tag and reader antennas and analysing the tag's radiation efficiency when operated close to the human body." Thesis, University of Bradford, 2012. http://hdl.handle.net/10454/6340.
Full textAbstract:
The aim of this study is to analysis, investigate and find out the solutions for the problems associated with the implementations of antennas RFID Reader and Tag for various applications. In particular, the efficiency of the RFID reader antenna and the detection range of the RFID tag antenna, subject to a small and compact antenna's design configuration have been studied. The present work has been addressed directly to reduce the cost, size and increase the detection range and communication reliability of the RFID framework antennas. Furthermore, the modelling concept of RFID passive tags mounted on various materials including the novel design of RFID reader antenna using Genetic Algorithm (GA) are considered and discussed to maintain reliable and efficient antenna radiation performances. The main benefit of applying GA is to provide fast, accurate and reliable solutions of antenna's structure. Therefore, the GA has been successfully employed to design examples: meander-line, two linear cross elements and compact Helical- Spiral antennas. In addition, a hybrid method to model the human body interaction with RFID tag antenna operating at 900MHz has been studied. The near field distribution and the radiation pattern together with the statistical distribution of the radiation efficiency and the absorbed power in terms of cumulative distribution functions for different orientation and location of RFID's tag antenna on the human body have been demonstrated. Several tag antennas wi th symmetrical and unsymmetrical structure configurations operating in the European UHF band 850-950 MHz have been fabricated and tested. . The measured and simulated results have been found to be in a good agreement with reasonable impedance matching to the typical input impedance of an RFID integrated circuit chip and nominal power gain and radiation patterns.
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Yagci, Tayfun. "Target Classification And Recognition Using Underwater Acoustic Signals." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/3/12606373/index.pdf.
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Nowadays, fulfillment of the tactical operations in secrecy has great importance for especially subsurface and surface warfare platforms as a result of improvements in weapon technologies. Spreading out of the tactical operations to the larger areas has made discrimination of targets unavoidable. Due to enlargement of the weapon ranges and increasing subtle hostile threats as a result of improving technology, &ldquovisual&rdquo
target detection methods left the stage to the computerized acoustic signature detection and evaluation methods. Despite this, the research projects have not sufficiently addressed in the field of acoustic signature evaluation. This thesis work mainly investigates classification and recognition techniques with TRN / LOFAR signals, which are emitted from surface and subsurface platforms and proposes possible adaptations of existing methods that may give better results if they are used with these signals. Also a detailed comparison has been made about the experimental results with underwater acoustic signals.
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Tano, Richard. "Determining multimediastreaming content." Thesis, Umeå universitet, Institutionen för fysik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-50376.
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This Master Thesis report was written by Umeå University Engineering Physics student Richard Tano during his thesis work at Ericsson Luleå. Monitoring network quality is of utmost importance to network providers. This can be done with models evaluating QoS (Quality of Service) and conforming to ITU-T Recommendations. When determining video stream quality there is of more importance to evaluatethe QoE (Quality of Experience) to understand how the user perceives the quality. This isranked in MOS (Mean opinion scores) values. An important aspect of determining the QoEis the video content type, which is correlated to the coding complexity and MOS values ofthe video. In this work the possibilities to improve quality estimation models complying to ITU-T study group 12 (q.14) was investigated. Methods were evaluated and an algorithm was developed that applies time series analysis of packet statistics for determination of videostreams MOS scores. Methods used in the algorithm includes a novel assembling of frequentpattern analysis and regression analysis. A model which incorporates the algorithm for usage from low to high bitrates was dened. The new model resulted in around 20% improvedprecision in MOS score estimation compared to the existing reference model. Furthermore an algorithm using only regression statistics and modeling of related statistical parameters was developed. Improvements in coding estimation was comparable with earlier algorithm but efficiency increased considerably.Detta examensarbete skrevs av Richard Tano student på Umeå universitet åt Ericsson Luleå. Övervakning av nätets prestanda är av yttersta vikt för nätverksleverantörer. Detta görs med modeller för att utvärdera QoS (Quality of Service) som överensstämmer med ITU-T rekommendationer. Vid bestämning av kvaliten på videoströmmar är det mer meningsfullt att utvärdera QoE (Quality of Experience) för att få insikt i hur användaren uppfattar kvaliten. Detta graderas i värden av MOS (Mean opinion score). En viktig aspekt för att bestämma QoE är typen av videoinnehåll, vilket är korrelerat till videons kodningskomplexitet och MOS värden. I detta arbete undersöktes möjligheterna att förbättra kvalitetsuppskattningsmodellerna under uppfyllande av ITU-T studygroup 12 (q.14). Metoder undersöktes och en algoritm utvecklades som använder tidsserieanalys av paketstatistik för uppskattning av videoströmmars MOS-värden. Metoder som ingår i algoritmen är en nyutvecklad frekventa mönster metod tillsammans med regressions analys. En modell som använder algoritmen från låg till hög bithastighet definierades. Den nya modellen gav omkring 20% förbättrad precision i uppskattning av MOS-värden jämfört med existerande referensmodell. Även en algoritm som enbart använder regressionsstatistik och modellerande av statistiska parametrar utvecklades. Denna algoritm levererade jämförbara resultat med föregående algoritm men gav även kraftigt förbättrad effektivitet.
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Frisch, Annett [Verfasser], Andreas [Akademischer Betreuer] Müller, and Dirk [Akademischer Betreuer] Müller-Wieland. "Analysis of nutritional patterns in individuals at risk for the development of the metabolic syndrome assessed by a food frequency questionnaire / Annett Frisch. Betreuer: Andreas Müller ; Dirk Müller-Wieland." Halle, Saale : Universitäts- und Landesbibliothek Sachsen-Anhalt, 2013. http://d-nb.info/1036872327/34.
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Henn, Ruth Liane. "Padrão alimentar e excesso de peso de uma população adulta da cidade de Porto Alegre, RS, 2005." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2006. http://hdl.handle.net/10183/7977.
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O presente estudo teve como objetivo identificar um ou mais padrões de dieta e verificar sua associação com excesso de peso em uma amostra de indivíduos adultos de Porto Alegre. Para avaliar a dieta, desenvolveu-se um questionário de freqüência alimentar (QFA) composto por 135 itens alimentares. A validade relativa do questionário foi verificada comparando-o à média de dois inquéritos recordatórios de 24 horas. A comparação entre os métodos foi realizada através dos coeficientes de correlação de Pearson e da classificação dos indivíduos segundo as distribuições em quartis de energia e nutrientes de cada método. Após ajuste para energia total e deatenuação, a correlação média entre os métodos foi 0,43. Em média, 76% dos participantes foram classificados no mesmo quartil ou quartis adjacentes; e somente 4% foram classificados em quartis opostos. Com base nas informações obtidas com o QFA, realizou-se análise exploratória de fatores para identificar padrões alimentares. A associação entre os padrões e excesso de peso foi testada utilizando-se análise de regressão de Poisson modificada, ajustando-se para variáveis de confundimento. Seis padrões foram derivados e explicaram 40,2% da variância total na ingestão de alimentos. Os rótulos atribuídos foram de acordo com os alimentos que mais contribuíram para o padrão: “Fast-food”, “Alimentos light/diet”, “Vegetais e frutas”, “Carnes e vísceras”, “Camarão e oleaginosas” e “Feijão e arroz”. O ajuste na análise para fatores de confusão mostrou que o aumento de uma unidade no escore do padrão “Carnes e Vísceras” elevou em 24% a prevalência de excesso de peso. Adicionalmente, houve tendência à redução nesta taxa entre aqueles que seguiam os padrões “Camarão e Oleaginosas” e “Feijão e Arroz”. Concluindo, o QFA apresentou validade razoável, o padrão “Carnes e vísceras” foi preditor de excesso de peso, enquanto os padrões “Camarão e oleaginosas” e “Feijão e arroz” mostraram tendência à proteção.The objective of this study was to identify one or more eating patterns and to evaluate the association between these patterns with excess of weight in a sample of adult from Porto Alegre. A food frequency questionnaire (FFQ), covering 135 food items, was developed to assess diet patterns. Relative validity of the FFQ was verified by comparison with the average of two 24-hour dietary recalls. The comparison between the two methods was carried out using Pearson correlation coefficient and cross-classification of individuals according to the quartile energy and nutrients distributions in each method. After adjustment for total energy intake and de-attenuation, the average correlation between the two methods was 0.43. On average, 76% of the participants were classified in the same quartile or in the adjacent quartiles; and only 4% were misclassified into the opposite quartiles. Based on of the information obtained from the FFQ, an exploratory analysis of factors was carried out to identify eating patterns. The association between eating patterns and overweight was tested using modified Poisson models, adjusting for confounding variables. Six patterns were derived and accounted for 40.2% of the total variance in food intake. These were labeled according to the food types that contributed most to the pattern: “Fast-food”, “Light/Diet Foods”, “Fruit and Vegetables”, “Meat and Animal products”; “Shrimp and Oily foods” and “Beans and Rice”. The analysis adjusting for confounding factors showed that the increase of one unit in the “Meat and Animal Products” pattern raised by 24% the prevalence of overweight. In addition, there was a trend to reduce overweight rate for those who had the “Shrimp and Oily Foods” and “Beans and Rice” patterns. In conclusion, the FFQ showed reasonable validity, the “Meat and Animal Products” pattern was a predictor of overweight, while the “Shrimp and Oily foods” and “Beans and Rice” patterns showed a trend to protect against excess of weight.
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Roberts, Geoff. "Classification of non-stationary signals using time-frequency representations and multiple hypotheses tests : an application to humpback whale songs." Thesis, Queensland University of Technology, 1999.
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Levy, Clara. "Etude instrumentale et numérique de la réponse dynamique d'une écaille calcaire potentiellement instable." Phd thesis, Université de Grenoble, 2011. http://tel.archives-ouvertes.fr/tel-00568701.
Full textAbstract:
Les éboulements rocheux sont difficilement prévisibles en raison de leur soudaineté et du peu d'informations disponibles sur la structure interne du massif rocheux. L'analyse en retour d'éboulements dans des falaises calcaires a montré qu'ils étaient initiés par la fracturation de ponts rocheux et que leur persistance était le principal paramètre à prendre en compte pour des calculs de stabilité. En 1er lieu, nous avons utilisé l'information contenue dans le bruit sismique afin d'évaluer le degré d'instabilité d'une écaille rocheuse. Les données viennent de la falaise calcaire de Chamousset (Vercors) où un réseau sismique a fonctionné 4 mois jusqu'à 2 semaines avant la chute d'une écaille de 21000 m3. Le calcul des spectres de bruit sismique a permis d'identifier la 1ère fréquence propre de l'écaille qui diminue significativement avant l'éboulement. Ce même réseau a enregistré des milliers d'événements dont les plus énergétiques ont été classés. Certains de ces signaux ont des arrivées d'ondes P et S distinctes, permettant d'analyser leur mécanisme de rupture et de calculer leur magnitude et distance hypocentrale. Des simulations favorisent l'hypothèse de ruptures en traction pour expliquer les polarisations. D'autres simulations confirment que les événements situés à l'interface écaille-massif entraînent la résonance de l'écaille, expliquant l'observation de codas mono-fréquentielle avec une amplitude sismique plus forte sur l'écaille. Enfin, l'étude de la réponse thermomécanique d'une 2nde écaille sur un an montre l'influence des paramètres météorologiques sur ses fréquences propres. Les effets réversibles et irréversibles sur ces fréquences ont été identifiés.
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Di, Renzo Antonio. "Sviluppo di metodologie per la qualifica di componenti mediante termoelasticità." Doctoral thesis, Università degli studi di Padova, 2007. http://hdl.handle.net/11577/3425002.
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The main subject of the thesis is the development of several methodologies aimed to qualify mechanical components through thermoelasticity.
Such essay begins with the analysis of the thermoelastic method of measure. We come to develop a new measure methodology of stress maps on mechanical rotation components through two test cases; they show their application to the stress analysis on the joint of water meter and fan cooling.
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Saavedra, Patricia Carolina Alejandra Rodríguez. "Análise do microfissuramento em rochas no ensaio de compressão diametral por meio da técnica de emissão acústica." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/18/18132/tde-10072017-095950/.
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Em nível microscópico, as rochas apresentam microdefeitos que agem como concentradores locais de tensão, favorecendo a ocorrência de ruptura frágil. O entendimento desse processo requer análises experimentais em rochas submetidas a tensões de tração. O ensaio de compressão diametral é uma alternativa apropriada, pois não apresenta as dificuldades envolvidas no ensaio de tração direta. A propagação de microfissuramento em materiais frágeis produz liberação de energia na forma de ondas elásticas chamadas de emissões acústicas (EA). O monitoramento com EA permite acompanhar a propagação de dano no corpo de prova (CP), sem perturbá-lo. Nesta pesquisa, CPs de mármore e monzogranito são submetidos a ensaios de compressão diametral com deslocamentos monotônicos e cíclicos, com controle de deslocamento. Aplica-se a técnica de EA, em conjunto com análises petrográficas, análises das curvas de força versus deslocamento e exame visual, para caracterizar o seu processo de microfissuramento. A localização tridimensional das fontes de EA foi realizada inicialmente utilizando-se o software AEwin® da PASA. Foi desenvolvido um programa de localização aprimorado que incorpora o cálculo da velocidade de propagação das ondas (vp) média para cada instante em que uma fonte é localizada. O novo programa (Crack Location by Acoustic emission with P Wave Velocity determination, CLAPWaVe) mostra um claro decréscimo da velocidade de propagação com o aumento do dano. O programa desenvolvido (CLAPWaVe) mostrou melhor ajuste e maior coerência com a literatura e com a condição final rompida dos CPs do que o software AEwin. Em mármore e monzogranito o microfissuramento se inicia a 25-30% e 75-85% do carregamento de pico, respectivamente, e localiza-se na vizinhança do centro do CP. Em ambas as rochas se acumulou, também, dano na região dos apoios do CP, associado à transferência de carregamento do berço ao CP. Antes do pico de carregamento, o microfissuramento tornou-se mais denso e localizado no centro e nos apoios do CP, embora a região central ainda concentre a maior parte. Após o pico, o microfissuramento acumulou-se em uma das faces do CP, progredindo até a outra face. O monzogranito apresentou ruptura progressiva do CP, enquanto que no mármore a maior parte da superfície de ruptura já está desenvolvida imediatamente após o pico. Durante o ensaio em ambas as rochas, no núcleo central foram registradas as menores velocidades vp do CP. Na região dos apoios, embora tenha havido microfissuramento, registraram-se as maiores velocidades vp no CP, pois o confinamento produzido pelo contato com o berço aumentou localmente a rigidez do CP. A distribuição não homogênea de vp no CP revelou que a consideração desse parâmetro como constante e igual à condição intacta ao longo do ensaio, como comumente encontrado na literatura, não representa a condição real do CP danificado. O microfissuramento no monzogranito se propaga principalmente através dos cristais de quartzo, seguindo um caminho tortuoso subparalelo à direção de carregamento e liberando altos níveis de energia absoluta. No mármore, a propagação segue os planos de clivagem da calcita, liberando níveis baixos de energia absoluta. Os histogramas da distribuição espacial da resistência em ambas as rochas mostraram bom ajuste a uma distribuição de Weibull, porém o monzogranito mostrou melhor ajuste e menor variabilidade que o mármore. As análises dos sinais no domínio das frequências mostraram que o microfissuramento é caracterizado por emissões de banda larga.At microscopic level, rocks exhibit microflaws, which act as local stress concentrators, favoring the occurrence of brittle failure. The understanding of this process requires experimental analyses of rock specimens under tensile stresses. The diametral compression test is an adequate alternative for such a studies, because it does not present the difficulties of direct tension tests. Crack propagation in brittle materials releases energy as transient elastic waves known as acoustic emission (AE). Monitoring with AE enables an insight into the cracking process without affecting the integrity of the sample. In this work, marble and monzogranite specimens were subjected to monotonic and cyclic displacementcontrolled diametral compression tests. The AE monitoring technique was applied in conjunction with petrographic analyses, interpretation of the load versus displacement curves and visual examination of the samples for the characterization of their cracking process. The three-dimensional localization of the AE sources was initially carried out by using the software AEwin® from PASA. An improved localization software, which considers the P-wave velocity variation along the damage process (vp) for each AE source was developed. The developed software (Crack Location by Acoustic emission with P Wave Velocity determination, CLAPWaVe) has shown greater consistency with literature and the final cracked samples and better accuracy than AEwin. Microcracking in monzogranite and marble initiated at 25-30% and 75-80% of the peak load, respectively, and is located at the center of the specimen. In addition, both rocks showed concentrated microcracking close to the region of contact between the specimen and the loading platens, related to the loading transference along the loading edge. Before peak load, microcracking becomes denser and localized at the center and the contact region of the specimen, although, the central region still concentrates the main portion of the damage. After the peak load, new microcracks were first concentrated on one of the faces at the center of the specimen and then propagated through its thickness all the way to the other face. The progressive failure in monzogranite extended through to the end of the test, while in marble the main portion of the failure surface of the specimen developed just after peak. During the whole test in both rocks, the lowest velocities (vp) of the specimen were recorded in the central core. Although microcracking was induced at the contact region, the highest velocities vp of the specimen were registered there, because of the confinement effect produced by the platens, which lead to a local increase in the stiffness of the specimen. The non-homogeneous distribution of vp in the specimen has revealed that the utilization of this parameter as a constant and equal to the value measured in the specimen before testing (as usually adopted in the literature), does not represent the real condition of the damaged specimen. In monzogranite, microcracks propagate mainly through quartz crystals, following a tortuous path subparallel to the loading direction, by releasing high-level of absolute energy, while in marble the propagation of microcracks follows the cleavage planes of calcite, by releasing low-level of absolute energy. The histograms of spatial strength distribution in both rocks have shown good adjustment to a Weibull distribution, but monzogranite exhibited a more accurate adjustment with lower variability than marble. The analysis of signals in the frequency domain showed that the microcracking is characterized by wide band emissions.
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Kincl, Zdeněk. "Metody pro testování analogových obvodů." Doctoral thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2013. http://www.nusl.cz/ntk/nusl-233583.
Full textAbstract:
Práce se zabývá metodami pro testování lineárních analogových obvodů v kmitočtové oblasti. Cílem je navrhnout efektivní metody pro automatické generování testovacího plánu. Snížením počtu měření a výpočetní náročnosti lze výrazně snížit náklady za testování. Práce se zabývá multifrekveční parametrickou poruchovou analýzou, která byla plně implementována do programu Matlab. Vhodnou volbou testovacích kmitočtů lze potlačit chyby měření a chyby způsobené výrobními tolerancemi obvodových prvků. Navržené metody pro optimální volbu kmitočtů byly statisticky ověřeny metodou MonteCarlo. Pro zvýšení přesnosti a snížení výpočetní náročnosti poruchové analýzy byly vyvinuty postupy založené na metodě nejmenších čtverců a přibližné symbolické analýze.
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Tisoň, Zdeněk. "Dolování sekvenčních vzorů." Master's thesis, Vysoké učení technické v Brně. Fakulta informačních technologií, 2012. http://www.nusl.cz/ntk/nusl-236614.
Full textAbstract:
This master's thesis is focused on knowledge discovery from databases, especially on methods of mining sequential patterns. Individual methods of mining sequential patterns are described in detail. Further, this work deals with extending the platform Microsoft SQL Server Analysis Services of new mining algorithms. In the practical part of this thesis, plugins for mining sequential patterns are implemented into MS SQL Server. In the last part, these algorithms are compared on different data sets.
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Ai-WeiChuang and 莊璦瑋. "Spatiotemporal Frequent Pattern Mining : A Case Study inCrime Pattern Analysis." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/hq49vv.
Full textAbstract:
碩士國立成功大學
資訊工程學系
102
Spatiotemporal pattern mining tried to discover unknown, potentially interesting and useful event sequences where events occur within a specific time interval and locate geographic close to each others. Previous works use partition or ill-defined representation of spatial objects and neglect some spatial properties exist in original spatiotemporal data. Moreover, traditional sequential pattern mining methods don't suit the non-transactional spatialtemporal database. In this paper we expose the disappearance of spatial correlation due to improper data representation and propose a naive approach to mine frequent sequential spatiotemporal pattern. The end of the paper is a case study of crime pattern analysis.
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Chen, Hsuan-Sheng, and 陳宣勝. "A Framework for Incorporating Frequent Pattern Analysis into Multimodal HMM Event Classification for Baseball Videos." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/16619009571669831961.
Full textAbstract:
博士國立交通大學
資訊科學與工程研究所
103
Semantic high-level event recognition of videos is one of most interesting issues for multimedia searching and indexing. Since low-level features are semantically distinct from high-level events, a hierarchical video analysis framework is needed, i.e. using mid-level features to provide clear linkages between low-level audio-visual features and high-level semantics. Therefore, this thesis presents a framework for video event classification using temporal context of mid-level interval-based multimodal features. In the framework, a co-occurrence symbol transformation method is proposed to explore full temporal relations among multiple modalities in probabilistic HMM event classification. Besides, data mining and frequent pattern analysis have recently become a popular way of discovering new knowledge from a data set. However, it is rarely applied to video semantic analysis. Therefore, this thesis introduces two methods: frequent-pattern trained HMM and frequent-pattern tailored HMM to incorporate frequent pattern analysis into multimodal HMM event classification for baseball videos. Moreover, different symbol coding methods including temporal sequence coding and co-occurrence symbol coding for multimodal HMM classification are compared. The results of our experiments on baseball video event classification demonstrate the superiority of the proposed approach and demonstrate that integration of frequent pattern analysis could help to improve event classification performances.
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CAMPAGNI, RENZA. "Data Mining Models for Student Databases." Doctoral thesis, 2013. http://hdl.handle.net/2158/803882.
Full textAbstract:
This thesis presents a data mining methodology to analyze the careers of University students, where a career is the ordered sequence of the exams taken by the single student. We present
different models based on clustering, classification and sequential pattern techniques in order to understand and improve the performance of students and the scheduling of exams. We introduce an ideal career as the career of an ideal student which has taken each examination just after the end of
the corresponding course, without delays. We then compare the career of a generic student with the ideal one by using these different techniques. Finally, we apply the methodology to a real case study and interpret the results which underline that the more students follow the order given by the ideal career the more they get good performance in terms of graduation time and final grade.
We also analyze the career of university students from another point of view, that is, we can study the perspective of each course, by analyzing the distribution of students with respect to the delay with which they take an examination, to discover common characteristics between two or more courses.
This is done in terms of Poisson distributions.
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Wang, Yu-Kai, and 王昱凱. "The Application of Data Mining Technique on Frequent Prescription Pattern Analysis among Different-Level Hospitals :Taking Diabetes mellitus and Essential Hypertension as Examples." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/61557238901516782870.
Full textAbstract:
碩士南台科技大學
企業管理系
93
The Department of Health has divided Taiwan hospitals into Medicare Center, Regional Hospital, Local Hospital, and Primary Medicare Care four levels; it aggressively pushes the “Hierarchical Medical Care System,” to expect the levels of hospitals can guard people’s health with the reasonable division of labor; although it also attempts to implement “the Hierarchical Medical Care System” by pricing factor; nevertheless, due to the defects of system design, the tendency of people to go for better hospital services and to take more medicines, so the general public normally possess the concept that “higher lever hospitals have better doctors with more effective prescriptions.” For understanding whether there is a distinct differentiation in frequent prescriptions of common diseases treatment (especially long-term chronic prescriptions needed) among different level hospitals; this study picked the Diabetes mellitus and the Essential Hypertension those most common chronic diseases from the “National Health Insurance Research Database,” which offered by the bureau of national health insurance; then, by using of the Apriori algorithm method to find out the most common and frequent prescription pattern in different level hospitals. Furthermore, this study analyze the common and frequent prescription pattern from medicine pharmacology, medicine price, and medicine ingredients three aspects; in the mean time, compare the variance of common and frequent prescription pattern among different level hospitals. In the comparison and analysis of the common prescription pattern in different level hospitals, with the abundant clinical experiences pharmacist’s help, we found there are certain kinds of common and frequent prescription pattern existed among different level hospitals, but no big difference in the prescriptions from the above three aspects. By extracted common and frequent prescription pattern, and the prescription pattern variance analysis’s result and procedure, this study hope can facilitate the bureau of national health insurance to implement the classification of different hospitals, also help the public to understand the common and frequent prescription pattern with different level hospitals, thus, to assist their hospital choices decision making.
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Ramos, Teresa Raquel do Monte. "A temporal analysis of frequent patterns - the impact on management." Master's thesis, 2021. https://hdl.handle.net/10216/138282.
Full text
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FURUHASHI, Takeshi, Tomohiro YOSHIKAWA, and Makoto SUZUKI. "Support Method for Reference of Documents based on Correspondence Analysis." 2012. http://hdl.handle.net/2237/20857.
Full textAbstract:
2012 Joint 6th International Conference on Soft Computing and Intelligent Systems (SCIS) and 13th International Symposium on Advanced Intelligent Systems (ISIS) (SCIS-ISIS 2012). November 20-24, 2012, Kobe, Japan
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Yu, Sheng-Te, and 游聲德. "Time-of-Day Distribution Patterns of Freeway Crash Frequency by Using Functional Data Analysis." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/m4hx6h.
Full textAbstract:
碩士國立交通大學
運輸與物流管理學系
105
Previous studies in freeway crash frequency modeling mostly used of count models (e.g. Poisson and Negative Binomial models) to investigate the effect of risk factors (commonly adopted factors including geometric variables, traffic variables, and environment variables) on the annual number of accidents on an analytical road segment. Few of them further considered the effect of these factors on the time-of-day distribution of accidents. The time distribution of accidents is essential for proposing strategies for accident prevention and effective emergency rescue. Based on this, this study uses of functional data analysis (FDA) – functional principal components analysis (FPCA), functional analysis of variance (FANOVA) and functional linear model (FLM)- to model and analyze the time-of-day distribution of accidents of analytical road segments. Where the functional principal component analysis can explain the variations of pattern, functional ANOVA helps to identify the effect of each of key factors and functional linear model can investigate how the functional key factors affect the distribution patterns of accidents. A case study on accidents data in Freeway No.1 with a total of 124 road segments formed by two adjacent interchanges and two directions (northbound and southbound) is conducted. The potential factors includes downward slope, curvature, number of lanes, posted speed camera, yearly rainfall, neighboring to metropolitan, traffic flows of small vehicles, large vehicles and trailer-tractors, and percentage of large vehicles and trailer-tractors. The results of FPCA show that three principal components of pattern variations are Increase in crash frequency in the morning peak hours, Increase in crash frequency in evening peak hours, and Decrease in crash frequency in the daytime off-peak hours. The results of FANOVA indicate that curvature, number of lanes and posted speed camera significantly affect the differences in the distribution patterns. At last, the functional linear modeling between functional traffic flows (small vehicles, large vehicles, trailer-tractors, percentage of large vehicles and trailer-tractors) and time-of-day distribution of crash frequency is analyzed. The results show that small vehicles traffic flow has the best explanatory power, suggesting the distribution patterns of accidents are best fitted to the distribution patterns of small vehicle traffic flow. However, the coefficient of determination is low, implying some missing important factors have not been considered in this study.
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Ahmed, A., and Yim Fun Hu. "3M relationship pattern for detection and estimation of unknown frequencies for unknown number of sinusoids based on Eigenspace Analysis of Hankel Matrix." 2013. http://hdl.handle.net/10454/9594.
Full textAbstract:
noAbstract: We develop a novel approach to estimate the n unknown constituent frequencies of a sinusoidal signal that comprises of unknown number, n, of sinusoids of unknown phases and unknown amplitudes. The approach has been applied to multiple sinusoidal signals in the presence of white Gaussian noise with varying signal to noise ratio (SNR). The approach is based on eigenspace analysis of Hankel matrix formed with the samples from averaged frequency spectrum of the signal obtained through multiple measurements. The eigenspace analysis is based on the newly developed 3M relationship which reflects and exploits the relationship between the consecutive sets of Maximum, Middle and Minimum eigenvalues of square symmetric matrix of the Hankel matrix. The 3M relationship exhibits a pattern in line with the order of the Hankel matrix and leads to parametric estimation of the constituent sinusoids. This paper also presents the relationship equation between the size of 3M relationship pattern and the dimensions of the Hankel matrix. The performance of the developed approach has been tested to correctly estimate multiple constituent frequencies within a noisy signal.
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Hsu, Yun-Shu, and 許雲旭. "Copula-based multisite spatial-temporal rainfall patterns and regional frequency analysis – A Case Study in Lan-Yang Basin." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/g9t29x.
Full textAbstract:
碩士國立臺灣大學
生物環境系統工程學研究所
102
Extreme rainfall events occur increasingly and cause enormous loss; consequently, regional frequency analysis has become more important and widely used to estimate the return period of floods. However, the dependence among stations was not considered in the past. Studies have shown that the variation of rainfall patterns was affected by monsoon, especially during winter, in I-Lan area, i.e. the northeast corner of Taiwan. The most important factor that affects the precipitation in I-Lan is the local circulation caused by the triangle-shaped terrain. Therefore, without the influence of strong weather systems, e.g. typhoon, extreme rainfall events still occur. The purpose of this study is applying techniques of copula to analyze the multisite stochastic hourly rainfall patterns and regional frequency considering the dependence among surrounding rainfall stations during the period of 1960-2011. This model is following three steps to analyze the rainfall patterns and return periods. First, we use copulas to model the dependence among rainfall stations without the influence of marginal distributions, and then pair-copula structures are applied to separate the multivariate copula into several of bivariate copulas. Second, conditional probability density function is used to realize the major space-time pattern of local precipitation with different scenarios. Finally, copula-based regional frequency analysis is compared with the index flood methods with L-moments, and the return period simulation IV considering dependence among stations is also exhibited in this part. After constructing the dependent structure, the joint density function can be used to simulate the complicate regional rainfall patterns and regional return periods. In a specific scenario, the rainfall in downstream is more than in upstream when the extreme rainfall event occurs in midstream. Furthermore, copula-based return periods considering dependence are more accord with the real events than the index flood methods with L-moments. Considering dependent structure by copula can not only simulate the complex rainfall patterns but also reduce the possibility of underestimated or overestimated situation.
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Ke, Huajie. "Fabrication, characterization and analysis of patterned nano-sized material with large magnetic permeability at high frequency." 2013. https://scholarworks.umass.edu/dissertations/AAI3603105.
Full textAbstract:
Magnetic mesoscopic and nano-sized structures have promising applications such as high-density data storage, magnetic field sensors, and microwave devices. Patterned magnetic structures are especially interesting because their constitutive material, sizes and geometry are easily adjustable in fabrication. This makes manipulation of electromagnetic properties possible and creates many novel features never discovered in conventional bulk materials. The artificial magnetic structures that can be engineered to meet specific application purposes are called magnetic metamaterials. This thesis aims to investigate magnetic materials nanostructured to produce high permeability and low loss performance at gigahertz (GHz) frequency region. Such property is highly desired for communication devices with miniaturized size, reduced energy consumption and enhanced signal detection sensitivity. Antennas, microwave field sensors are the examples of applications. We first analyze the single domain model for ac magnetization to get theoretical understanding and prediction. Then we evaluate all free energy terms for a magnetic dipole to know which energies (or fields) are contributing to the effective magnetic field in our real experiments. Secondly experiment work including fabrication, dc characterization and ac characterization of Permalloy and cobalt nanoscale magnetic structures, as well as FePt nanoparticles are covered. Different microwave techniques regarding sensitive magnetic permeability measurements are discussed in detail for comparison. In the last chapter, micromagnetic simulations are performed to obtain broadband ac magnetization response spectrum for a single Permalloy nanowire and two interacting Permalloy nanowires.
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Yi-RuHong and 洪逸如. "Rainfall Pattern Analysis on Mountain Highway Slope Hazards and Preliminary Study on Frequency Model-A Case Study on Da-Jia River Region." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/30673592927154611752.
Full textAbstract:
碩士國立成功大學
土木工程學系碩博士班
100
The aim of this study is to investigate the influence of the strength of precipitation to the stability of slope land along highways those spreading in the watershed of river Da-Jia during typhoons Toraji, Mindulle and Morakot. By collecting the historical precipitation data in site, the completed rainfall events during those typhoons can be obtained and be adopted to calculate the accumulated rainfall(R) and rainfall intensity(I) of the watershed. Furthermore, the concept of rolling rainfall intensity is proposed to illustrate that accumulated rainfall and rainfall intensity are not only the factors that led to the damage of slope land along the highway, the effect of duration of the rainfall intensity has to be included. Furthermore, accumulated rainfall and rolling rainfall intensity are also used to establish the snake line that is the analysis model of rainfall hydrograph and can be expressed the variations of accumulated rainfall and rolling rainfall intensity with time. In addition, both physiographical conditions and the rainfall data in area where disasters were occurred were collected. The physiographical conditions can be classified as four factors which as elevation, degree of slope, direction of slope and geologic condition and with Log-Pearson Type Ⅲ Distribution, the rainfall data is used to calculate the recurrence interval and classified it according to the severity of the disasters in the past for frequency analysis. By combining the results of classification and analysis with the snake line, the critical rainfall envelope of the study area can be defined. The disaster event occurred on June 10, 2012 is verified with the critical rainfall envelope. It is shown that the critical rainfall envelope can be the basis for the disaster capacity of mountain highway slope.
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Thella, 'Mamashome Amelia. "Refining geography teaching : an error analysis." Thesis, 2009. http://hdl.handle.net/10539/5925.
Full textAbstract:
Sexual abstinence has become the primary response to prevention against sexually
transmitted infection (STI) and unplanned pregnancies amongst young people. However,
not much is known about the perceptions of young men on sexual abstinence. The central
aim in this study was to explore the perceptions of sexual abstinence among young black
males. The research aims to examine men’s understandings of their own sexuality and the
way these might influence their decision on sexual abstinence. A total of 10 in-depth
semi-structured interviews were conducted individually with young men aged between 18
and 25 years, studying at The University of the Witwatersrand. All data collected were
then qualitatively analysed through the use of thematic content analysis (TCA). Findings
show that in constructing their masculinities participants predominantly endorsed
discourses of male hegemony. At some instances the young men retracted to subjective
alternative masculinities, although there was a stronger need to fit in with their peers, to
protect themselves from being ridiculed or rejected. As such conforming to the
hegemonic masculinity was expected. The young men constructed women as sexual
objects and as a means towards affirming their masculinity.
A key conclusion drawn was that some traditional notions of manhood still held sway,
and these tied in strongly with how these participants constructed their masculinity and
this influenced most of them to not sexually abstain.
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Μπουγιούκος, Παναγιώτης. "Functional classification of proteins using mass spectrometry data and exploration of their frequency of identification in proteomic analysis." Thesis, 2009. http://nemertes.lis.upatras.gr/jspui/handle/10889/2486.
Full textAbstract:
Prostate cancer is a significant public health concern due to its high incidence and mortality, and that no consensus exists regarding the best form of treatment for any stage of the disease. Prostate cancer mortality can be reduced by the early prostate cancer detection. The earlier the detection the more effective the treatment would be. Prostate cancer screening or early detection has been accomplished applying the digital rectal examination (DRE) , the measurement of serum the prostate specific antigen (PSA), transrectal ultrasonography and combinations of these tests. MS based proteomics and particularly MS-SEDLI-TOF technology have assisted in discovering prostate cancer biomarkers.
On the other hand, a major cause of mortality for women is the ovarian cancer. Malignant ovarian tumors are heterogeneous in their biological and clinical behaviour and a greater understanding of how they develop and progress is a prerequisite to successful early detection, screening programs, and treatment modalities.
Accordingly, the aims of the present thesis are: (i) To develop a reliable pattern recognition system for the discrimination of healthy from patients with prostate cancer as well as controls from patients with ovarian cancer ,(ii) To develop efficient algorithms in order to handle the large number of features that are extracted from proteomic spectra, (iii) To develop a methodology to facilitate the investigation of the low intensity peaks which are the peaks in which biologists are mostly interested in, (iv) To propose potential biomarkers for discriminating healthy from prostate cancer cases and healthy from ovarian cancer cases . To cope with the above issues and in search of efficient methods for handling proteomic spectra a novel multi classifier pattern recognition methodology has been designed, developed and implemented, for the analysis of prostate and ovarian proteomic data. Furthermore, a novel method for splitting and grouping peaks according to their intensities has been developed to be consistent with biologist interest in investigating low intensity peaks.Τα δεδομένα πρωτεομικής τα οποία εξάγονται από φασματογράφο μάζας έχουν ως αποτέλεσμα την δημιουργία ενός μονοδιάστατου σήματος το οποίο στον οριζόντιο άξονα έχει τιμές μάζας/φορτίο και στον κατακόρυφο άξονα έχει τις αντίστοιχες τιμές έντασης. Οι τιμές στον οριζόντιο άξονα (μάζα/φορτίο) οι οποίες αντιπροσωπεύουν πεπτίδια ή πρωτεΐνες έχουν ένα εύρος από 0 έως δεκάδες χιλιάδες. Επομένως τα πρωτεομικά φάσματα θεωρούνται ιδιαίτερα πολύπλοκα. Η διαχείριση της πληροφορίας των πρωτεομικών φασμάτων καθώς και η εξαγωγή διαγνωστικών συμπερασμάτων είναι ένα πεδίο ανοιχτό προς έρευνα. Ο καρκίνος του προστάτη αποτελεί την δεύτερη πιο σημαντική αιτία θανάτου στην Ηνωμένες Πολιτείες Αμερικής και τον Καναδά. Η θνησιμότητα που οφείλεται στον καρκίνο του προστάτη μπορεί να μειωθεί από την έγκαιρη πρόγνωσή του. Όσο ποιο έγκαιρη είναι η πρόγνωσή του τόσο ποιο αποτελεσματική είναι η θεραπεία του. Ο προστάτης είναι ένας αδένας που βρίσκεται στο εσωτερικό του σώματος, κάτω από την ουροδόχο κύστη του άνδρα και περιβάλλει την ουρήθρα. Τον αδένα αυτό τον έχει ένας άνδρας ήδη από την στιγμή που γεννιέται. Με την λειτουργία του συμβάλει, στον έλεγχο της ούρησης, το οποίο το πετυχαίνει λόγω της ανατομικής του θέσης, στον εμπλουτισμό του σπέρματος με χρήσιμα και απαραίτητα συστατικά και στη λειτουργία της εκσπερμάτισης. Ο καρκίνος του προστάτη είναι η ανάπτυξη καρκινικών κυττάρων στον αδένα αυτόν. Τα καρκινικά κύτταρα πολλαπλασιάζονται πολύ πιο γρήγορα από τα φυσιολογικά κύτταρα, και έτσι, η ολοένα αυξανόμενη συγκέντρωσή τους δημιουργεί όγκους. Επιπλέον, τα καρκινικά κύτταρα έχουν την δυνατότητα να μεταφέρονται σε άλλα σημεία του σώματος (κάνουν μετάσταση) και να καταστρέφουν τα υγιή κύτταρα. Η πρωτεομική με την εφαρμογή της φασματογραφίας μάζας έχει βοηθήσει σημαντικά στην πρόγνωση του καρκίνου του προστάτη και στην ανακάλυψη γνωστών βιοδεικτών του καρκίνου του προστάτη όπως είναι το ειδικό αντιγόνο του προστάτη (PSA), η προστατική όξινη φωσφατάση (PAP), το ειδικό πεπτίδιο του προστάτη (PSP) και το ειδικό αντιγόνο μεμβράνης του προστάτη (PSMA). Ο καρκίνος των ωοθηκών είναι μια συνήθεις γυναικολογική κακοήθεια με ποικίλα ιστολογικά χαρακτηριστικά. Είναι η κύρια αιτία θανάτου από καρκίνου ανάμεσα σε όλες τις γυναικολογικές κακοήθειες, καθώς και ο πέμπτος πιο συχνός τύπος καρκίνου μεταξύ γυναικών του δυτικού κόσμου. Η πλειοψηφία των κακοηθών όγκων των ωοθηκών εμφανίζεται σε γυναίκες ηλικίας άνω των 65 χρόνων, ενώ οι καλοήθεις όγκοι είναι συνηθέστεροι σε νεότερης ηλικίας γυναίκες μεταξύ 25 και 45 χρόνων. Λόγω της πολυπαραγοντικής φύσης του καρκίνου, είναι πολύ πιθανό, μια ομάδα βιοδεικτών να είναι πιο ενδεικτικοί για την πρόβλεψη της βιολογικής συμπεριφοράς διαφόρων όγκων, από την χρήση ενός μόνο βιοδείκτη. Το CA-125 είναι ένας δείκτης ο οποίος χρησιμοποιείται για την διάγνωσης και συγκεκριμένα στην πρόγνωση του καρκίνου των ωοθηκών. Η επιβεβαίωση του και αξιοπιστία του βιοδείκτη CA-125 οδήγησε στην ευρέως χρήση του, ως βιοδείκτης για τον καρκίνο των ωοθηκών, καθώς και στην κλινική διάγνωση της ανταπόκρισης του ασθενούς κατά την θεραπεία του καρκίνου. Πρόσφατες προσπάθειες επικεντρώθηκαν στην βελτίωση της διαγνωστικής ακρίβειας του CA-125, είτε χρησιμοποιώντας μόνο τον συγκεκριμένο βιοδείκτη (CA-125), είτε χρησιμοποιώντας τον με νέους βιοδείκτες που έχουν συσχετιστεί με τον καρκίνο των ωοθηκών. Ο βιοδείκτης CA-125 βρίσκεται στο μητρικό γάλα και στο αμνιακό υγρό στις υγιείς γυναίκες. Παρόλα αυτά υπάρχει επίσης σε γυναίκες με γυναικολογικά προβλήματα όπως μητρικό λειομύωμα και ενδομητρίωση μειώνοντας έτσι την ειδικότητα του βιοδείκτη. Επιπροσθέτως άλλοι βιοδείκτες οι οποίοι έχουν βρεθεί είναι οι prostasin, OVX1, CA-15.3, CA-72.4, και inhibin. Έτσι οι στόχοι της παρούσας διατριβής είναι: (i) ο κατάλληλος συνδυασμός των βημάτων, προεπεξεργασίας, εξαγωγής χαρακτηριστικών, επιλογής χαρακτηριστικών και επιλογής ταξινομητή ώστε η διάγνωση να είναι ακριβέστερη από τις υπάρχουσες μεθόδους. (ii) να προταθούν βιοδείκτες (biomarkers) και συγκεκριμένα τιμές φάσματος (μάζας/φορτίου) οι οποίες ενδεχομένως να σχετίζονται με τις ασθένειες προς μελέτη (Καρκίνου του προστάτη και των ωοθηκών). Για την εκπλήρωση των ανωτέρω στόχων σχεδιάστηκαν και αναπτύχθηκαν μεθοδολογίες με στόχο την ακριβή διάκριση των υγειών από ασθενείς με καρκίνο του προστάτη και ωοθηκών. Προτείνονται τιμές μάζας/φορτίο οι οποίες ενδεχομένως να αποτελέσουν χρήσιμους βιοδείκτες για τον καρκίνο του προστάτη και για τον καρκίνο των ωοθηκών. Επίσης υλοποιήθηκε μεθοδολογία για να μπορέσουμε να ερευνήσουμε την διαγνωστική αξία των κορυφών, των πρωτεομικών φασμάτων, με διάφορες τιμές έντασης και κυρίως των χαμηλών, οι οποίες θεωρούνται ως πλούσιες σε πληροφορία από τους βιολόγους.
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(5929478), Hao Bai. "Non-Destructive Evaluation of the Condition of Subsurface Drainage in Pavement Using Ground Penetrating RADAR (GPR)." Thesis, 2020.
Find full textAbstract:
Pavement drainage systems are one of the key drivers of pavement function and longevity, and effective drain maintenance can significantly extend a pavement's service life. Maintenance of these drains, however, is often hampered by the challenge of locating the drains. Ground Penetrating Radar (GPR) typically offers a rapid and effective method to detect these underground targets. However, typical detection schema that rely upon the observation of the hyperbolic return from a GPR scan of a buried conduit still tend to miss many of the older drains beneath pavements as they may be partially or fully filled with sediment and/or may be fabricated from clay or other earthen materials, yielding a return signal that is convolved with significant background noise.
To manage this challenge, this work puts forward an improved background noise and clutter reduction method to enhance the target signals in what amounts to a constructed environment that tends to have more consistent subsurface properties than one might encounter in a general setting. Within this technique, two major algorithms are employed. Algorithm 1 is the core of this method, and plays the role of reducing background noise and clutter. Algorithm 2 is supplementary, and helps eliminate anomalous discontinuous returns generated by the equipment itself, which could otherwise lead to false detection indications in the output of Algorithm 1. Instead of traditional 2-D GPR images, the result of the proposed algorithms is a 1-D plot along the survey line, highlighting a set of “points of interest” that could indicate buried drain locations identified at any given GPR operating frequency. Subsurface exploration using two different operating frequencies, 900 MHz and 400 MHz herein, is then employed to further enhance detection confidence. Points of interest are ultimately coded to define the confidence of the detection. Comparing the final result of proposed algorithms with the original GPR images, the improved algorithm is demonstrated to provide significantly improved detection results, and could potentially be applied to similar problems in other contexts.
Besides the background reduction methods, a group of simulations performed using GPRMAX2D software are examined to explore the influence of road cross-section designs on sub-pavement drainage conduit GPR signatures, and evaluate the effectiveness of alternate GPR antennae configurations in locating these buried conduits in different ground conditions. Two different models were explored to simulate conduit detection. In addition, different pipe and soil conditions were modeled, such as pipe size, pipe material, soil moisture level, and soil type. Four different quantitative measurements are used to analyze GPR performance based on different key factors. The four measurements are 1) signal to background ratio (SBR) in dB; 2) signal to receiver noise ratio (SNR) in dB; 3) signal energy in Volts; and 4) average signal band power in Watts.
The water and clay content of subsurface soil can significantly influence the detection results obtained from ground penetrating radar (GPR). Due to the variation of the material properties underground, the center frequency of transmitted GPR signals shifts to a lower range as wave attenuation increases. Examination of wave propagation in the subsurface employing an attenuation filter based on a linear system model shows that received GPR signals will be shifted to lower frequencies than those originally transmitted. The amount of the shift is controlled by a wave attenuation factor, which is determined by the dielectric constant, electric conductivity, and magnetic susceptibility of the transmitted medium. This work introduces a receiver-transmitter-receiver dual-frequency configuration for GPR that employs two operational frequencies for a given test - one higher and one slightly lower - to take advantage of this phenomenon to improve subpavement drain detection results. In this configuration, the original signal is transmitted from the higher frequency transmitter. After traveling through underground materials, the signal is received by two receivers with different frequencies. One of the receivers has the same higher center frequency as the transmitter, and the other receiver has a lower center frequency. This configuration can be expressed as Rx(low-frequency)-Tx(high-frequency)-Rx(high-frequency) and was applied in both laboratory experiments and field tests. Results are analyzed in the frequency domain to evaluate and compare the properties of the signal obtained by both receivers. The laboratory experiment used the configuration of Rx(400MHz)-Tx(900MHz)-Rx(900MHz). The field tests, in addition to the configuration used in the lab tests, employed another configuration of Rx(270MHz)-Tx(400MHz)-Rx(400MHz) to obtain more information about this phenomenon. Both lab and field test results illustrate the frequency-shift phenomenon described by theoretical calculations. Based on the power spectrum for each signal, the lower frequency antenna typically received more energy (higher density values) at its peak frequency than the higher frequency antenna.