Dissertations / Theses on the topic 'Stance prediction'
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Ruggeri, Federico. "Predizione della struttura di un argomento con feature di stance classification." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amslaurea.unibo.it/15009/.
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Nell'ultimo decennio i settori di ricerca nell'ambito dell'elaborazione automatica del linguaggio naturale (NLP) hanno acquisito sempre maggiore interesse, in concomitanza con l'introduzione continua di strumenti di machine learning innovativi.
In generale, seppur sia comunque presente un'ambizione ideologica, l'interesse principale è riconducibile ad un piano prettamente applicativo, di natura sociale o politica, dove l'introduzione di nuove informazioni può apportare un notevole miglioramento in molti processi di interesse reale e contribuire all'indagine di nuove tendenze e/o conflitti. Il potenziale riscontrato nei presenti ambiti di ricerca ha attirato l'attenzione di aziende di notevole portata, al punto da finanziare progetti ambiziosi volti a rispondere a necessità emergenti proprie di molteplici realtà di diversa natura.
A partire da queste premesse, il presente elaborato si pone come obiettivo la definizione di un modello atto a individuare punti di affinità tra due specifiche attività di recente interesse, denominate stance classification e argument structure prediction.
I primi due capitoli introducono rispettivamente i concetti di stance classification e argumentation mining, soffermandosi, in particolar modo, sulle tecniche e le metodologie impiegate. Il terzo capitolo affronta il tema della definizione di uno strumento di classificazione comparabile con lo stato dell'arte nell'ambito della stance classification. Il quarto capitolo si interessa principalmente dell'individuazione di un legame tra i due settori di ricerca presi in esame, per poi mettere a confronto alcune tecniche specifiche attualmente impiegate per l'argument structure prediction con le principali adottate nell'ambito della stance classification. Infine, nel quinto e ultimo capitolo viene proposto un nuovo corpus per la sperimentazione degli stessi approcci impiegati nel capitolo precedente, con particolare attenzione a proporre degli opportuni test di confronto e di verifica.
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Wojatzki, Michael Maximilian [Verfasser], and Torsten [Akademischer Betreuer] Zesch. "Computer-assisted understanding of stance in social media : formalizations, data creation, and prediction models / Michael Maximilian Wojatzki ; Betreuer: Torsten Zesch." Duisburg, 2019. http://d-nb.info/1177681471/34.
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LeeTiernan, Scott. "Modeling and predicting stable response variation across situations /." Thesis, Connect to this title online; UW restricted, 2002. http://hdl.handle.net/1773/9076.
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Bingham, Jeffrey Thomas. "A framework to quantify neuromechanical contributions to stable standing balance: Modeling predictions and experimental observations." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/52161.
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Interactions between the neural and musculoskeletal systems are a prerequisite for the production of robust movement. In spite of this, the neural control and musculoskeletal structure underlying biological movements are typically studied independently, with little attention paid to how changes in one may affect the other. Understanding these interactions may be critical to improving current rehabilitation technologies and therapy methods. As an example, balance disorders are multifactorial in nature and identifying whether biomechanical or neural changes are the source of instability remains an unanswered question.
I have used a combined experimental and modeling approach to understand neural and biomechanical interactions governing human balance control. I developed a simple four-bar linkage model with delayed feedback to investigate frontal-plane standing balance. Using methods from time-delay systems I present evidence from this model that biomechanical structure is important for behavioral function and show that neural control and biomechanical structure co-vary for stable human balance. Predictions from the model were tested experimentally to dissociate the effects of inertia and postural configuration on balance. In addition, I applied robust control methods to solve the difficult problem of comparing the relative performance between neuromechanical systems that differ in parameter values and predicted a common mechanism to explain changes in neural control across biomechanical contexts.
In the future, the analytical tools and simulation methods I have developed can be generalized to investigate changes in neuromechanical interactions of various deficits in biomechanics (ACL rupture, amputation) and neural control (Parkinson's disease, stroke). Furthermore, this approach can be used to explain how neural control and biomechanical structure relate to the diversity of animal form and function, as well as suggest biomimetic control policies for robotics.
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Chevalier, Samuel Chapman. "Inference, estimation, and prediction for stable operation of modern electric power systems." Thesis, Massachusetts Institute of Technology, 2021. https://hdl.handle.net/1721.1/130842.
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Thesis: Ph. D. in Mechanical Engineering and Computation, Massachusetts Institute of Technology, Department of Mechanical Engineering, February, 2021Cataloged from the official PDF of thesis.
Includes bibliographical references (pages 261-277).
To keep pace with social-ecological disruptions and technological progressions, electrical power systems must continually adapt. In order to address the stability-related challenges associated with these adaptations, this thesis develops a set of analytically rigorous yet practically oriented methods for ensuring the continued stability of modern power systems. By leveraging inference, estimation, and predictive modeling techniques, the proposed methods capitalize on the unprecedented amount of real time data emerging from modernizing smart grids. For each method, we provide simulated test results from IEEE benchmark systems. Newly deployed Phasor Measurement Units (PMUs) are observing the presence of detrimental low frequency forced oscillations (FOs) in transmission grid networks. To begin this thesis, we address the problem of locating the unknown sources of these FOs.
To perform source identification, we develop an equivalent circuit transformation which leverages suitably constructed transfer functions of grid elements. Since FO sources appear in this equivalent circuit as independent current injections, a Bayesian framework is applied to locate the most probable source of these injections. Subsequently, we use our equivalent circuit to perform a systematic investigation of energy-based source identification methods. We further leverage this equivalent circuit transformation by developing "plug-and-play" stability standards for microgrid networks that contain uncertain loading configurations. As converter-based technology declines in cost, microgrids are becoming an increasingly feasible option for expanding grid access. Via homotopic parameterization of the instability drivers in these tightly regulated systems, we identify a family of rotational functions which ensure that no eigenmodes can be driven unstable.
Any component which satisfies the resulting standards can be safely added to the network, thus allowing for plug-and-play operability. High-fidelity linearized models are needed to perform both FO source identification and microgrid stability certification. Furthermore, as loss of inertia and real-time observability of grid assets accelerate in tandem, real-time linearized modeling is becoming an increasingly useful tool for grid operators. Accordingly, we develop tools for performing real-time predictive modeling of low frequency power system dynamics in the presence of ambient perturbations. Using PMU data, we develop a black-box modeling procedure, known as Real-Time Vector Fitting (RTVF), that takes explicit account for initial state decay and concurrently active input signals. We then outline a proposed extension, known as stochastic-RTVF, that accounts for the corrupting effects of unobservable stochastic inputs.
The surrogate modeling utilized by vector fitting can also be applied to the steady state power flow problem. Due to an unprecedented deployment of distributed energy resources, operational uncertainty in electrical distribution networks is increasing dramatically. To address this challenge, we develop methodology for speeding up probabilistic power flow and state estimation routines in distribution networks. We do so by exploiting the inherently low-rank nature of the voltage profile in these systems. The associated algorithms dynamically generate a low-dimensional subspace which is used to construct a projection-based reduced order model (ROM) of the full nonlinear system. Future system solves using this ROM are highly efficient.
by Samuel Chapman Chevalier.
Ph. D. in Mechanical Engineering and Computation
Ph.D.inMechanicalEngineeringandComputation Massachusetts Institute of Technology, Department of Mechanical Engineering
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Handl, Tomáš. "Algoritmus Vivaldi pro nalezení pozice stanice v Internetu." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2009. http://www.nusl.cz/ntk/nusl-218110.
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Diploma thesis deals with usage of artificial coordinate systems used for localization of a station on the internet and prediction of delay between the stations. There are described and compared basic properties of centralized and decentralized algorithms providing station localization on the internet and RTT prediction. More in depth are presented main representatives of both types of algorithms such as GNP, IDMAPS or Lighthouse. Central part of thesis is aimed at getting to know Vivaldi distributed algorithm. Basic principle of the algorithm for constant and variable time step, using two dimensional coordinate system with 3rd parameter height, is here outlined. Further more implementation of this algorithm as a library Vivaldi-lib in the environment of Java is implemented. Part of the thesis are simulations of behaviour of this algorithm for both variations realized on artificial networks and data obtained from PlanetLab experimental network, using simulation created program VIVALDIMONITOR.
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Wangerin, Spencer D. "Development and validation of a human knee joint finite element model for tissue stress and strain predictions during exercise." DigitalCommons@CalPoly, 2013. https://digitalcommons.calpoly.edu/theses/1129.
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Osteoarthritis (OA) is a degenerative condition of cartilage and is the leading cost of disability in the United States. Motion analysis experiments in combination with knee-joint finite element (FE) analysis may be used to identify exercises that maintain knee-joint osteochondral (OC) loading at safe levels for patients at high-risk for knee OA, individuals with modest OC defects, or patients rehabilitating after surgical interventions. Therefore, a detailed total knee-joint FE model was developed by modifying open-source knee-joint geometries in order to predict OC tissue stress and strain during the stance phase of gait. The model was partially validated for predicting the timing and locations of maximum contact parameters (contact pressure, contact area, and principal Green-Lagrangian strain), but over-estimated contact parameters compared with both published in vivo studies and other FE analyses of the stance phase of gait. This suggests that the model geometry and kinematic boundary conditions utilized in this FE model are appropriate, but limitations in the material properties used, as well as potentially the loading boundary conditions represent primary areas for improvement.
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Verde, Joshua A. "Lake Powell Food Web Structure: Predicting Effects of Quagga Mussel." BYU ScholarsArchive, 2017. https://scholarsarchive.byu.edu/etd/6702.
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Food webs in aquatic ecosystems can be dramatically altered by invasive species. Quagga mussels are prevalent invaders that compete with existing species and disrupt nutrient cycling. In 2012, the Quagga Mussel (Dreissena rostriformus bugensis) was introduced into Lake Powell and is expected to move throughout the reservoir in the near future. Stable isotope analysis is a powerful tool for characterizing food webs and trophic interactions. To predict the long-term effects of Quagga Mussels, we used stable isotope analysis of primary producers, primary consumers, prey fish species, and predator fish species in Lake Powell to determine food web structure. Quagga Mussel are positioned to disrupt the pelagic arm of the food web by interfering with the link between phytoplankton and herbivorous zooplankton. This will likely have negative impacts on pelagic fish such as striped bass (Morone saxatilis) and threadfin shad (Dorosoma petenense). Quagga Mussel may also boost benthic productivity in the littoral zone by diverting nutrients from the water column to the benthos. This may have positive impacts on littoral fishes such as largemouth bass (Micropterus salmoides), smallmouth bass (Micropterus dolomieu), bluegill (Lepomis macrochirus), and green sunfish (Lepomis cyanellus).
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Oh, Yunje. "Prediction of steady state response in dynamic mode atomic force microscopy and its applications in nano-metrology." The Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=osu1135222817.
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Hopf, Konstantin [Verfasser], and Thorsten [Akademischer Betreuer] Staake. "Predictive Analytics for Energy Efficiency and Energy Retailing / Konstantin Hopf ; Betreuer: Thorsten Staake." Bamberg : University of Bamberg Press, 2019. http://d-nb.info/1191183580/34.
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Vedin, Ola. "Prevalence and Prognostic Impact of Periodontal Disease and Conventional Risk Factors in Patients with Stable Coronary Heart Disease." Doctoral thesis, Uppsala universitet, Institutionen för medicinska vetenskaper, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-260564.
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The purpose of this thesis was to assess the prevalence and management of established cardiovascular (CV) risk factors and the prevalence and influence of self-reported markers (number of teeth and frequency of gum bleeding) of periodontal disease (PD), a less explored CV risk factor, in patients with stable chronic coronary heart disease (CHD). We studied patients from the global STabilization of Atherosclerotic plaque By Initiation of darapLadIb TherapY (STABILITY) trial (n=15,828), in which patients with stable chronic CHD were randomized to either darapladib or placebo. Our studies were performed using descriptive statistics and multivariable linear, logistic and Cox regression models. The use of secondary preventive medications was generally high across the whole study population. Despite this, CV risk factors were highly prevalent, including obesity, hypertension and hypercholesterolemia. Achievement of guideline-recommended treatment targets was lacking and little improvement was seen throughout the study duration. Approximately 40% of patients reported having <15 remaining teeth and 25% reported gum bleeding. More tooth loss was associated with a greater CV risk factor burden after adjustment, while the associations for gum bleeding were less evident. After multivariable adjustment for CV risk factors and socioeconomic status, more tooth loss was associated with an increased risk of major adverse CV events (a composite of CV death, myocardial infarction and stroke), CV mortality, all-cause mortality and fatal or non-fatal stroke. We found associations between a higher degree of tooth loss and elevated levels of several prognostic biomarkers known to reflect various pathophysiological mechanisms involved in CV morbidity and mortality. Most biomarkers had little attenuating effect on the relationship between tooth loss and outcomes in a multivariable model. In conclusion, we found an inadequate CV risk factor control despite a high use of evidence-based pharmacological therapies, likely to explain some of the excess risk in CHD patients. Further, we demonstrated a high prevalence of PD markers, tooth loss in particular, that were associated with a wide range of established CV risk factors, prognostic biomarkers and outcomes. Collectively, these findings indicate that tooth loss may be a significant risk factor among patients with stable chronic CHD.
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Oesting, Marco [Verfasser], Martin [Akademischer Betreuer] Schlather, and Robert [Akademischer Betreuer] Schaback. "Spatial Interpolation and Prediction of Gaussian and Max-Stable Processes / Marco Oesting. Gutachter: Martin Schlather ; Robert Schaback. Betreuer: Martin Schlather." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2012. http://d-nb.info/1042970890/34.
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Asiimwe, Alex. "Morbidity and mortality in patients with stable and unstable COPD : construction and validation of a prediction model using routinely collected data." Thesis, University of Portsmouth, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.478895.
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Stange, Michael [Verfasser], and Albrecht E. [Akademischer Betreuer] Melchinger. "QTL mapping and genomic prediction of complex traits based on high-density genotyping in multiple crosses of maize (Zea mays L.) / Michael Stange. Betreuer: Albrecht E. Melchinger." Hohenheim : Kommunikations-, Informations- und Medienzentrum der Universität Hohenheim, 2013. http://d-nb.info/1045276243/34.
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Gembiczká, Adriana. "Analýza trhu bydlení pro seniory: stane se zajištění sociálních služeb v oblasti bydlení pro seniory podnikatelským cílem budoucnosti?" Master's thesis, Vysoká škola ekonomická v Praze, 2011. http://www.nusl.cz/ntk/nusl-125200.
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The diploma thesis is aim at analysis of determinants that determine whether is the market of homes for the elderly and homes with special regime attractive for current and potential entrepreneurs. Theoretical part explains the phenomenom of population ageing, analyzes predictions of population development and the development of number of people suffering from Alzheimer disease, senior's financial resources, reasearches rights and duties of social services providers and analyzes effectiveness of financing the social services according to the type of founder. For needed findings is used analysis of specialized literature and studies. Analytical part analyzes preferences for examined kinds of social services. Offers practical example of running the home with special regime and brings the opinions of specialists on economization of social services. In the end of work are collected findings evaluate by means of SWOT analysis.
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Edwards, Keith. "A proposed methodology for predicting the carbon and nitrogen stable isotope measures of K'inich Yax K'uk Mo', Copan dynastic founder." Master's thesis, University of Central Florida, 2011. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4887.
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The purpose of this thesis is to show that stable isotope analysis can be used to predict K'inich Yax K'uk Mo's stable isotope measures based on Stuart's (2007) hypothesis that K'inich Yax K'uk Mo', the dynastic founder of the Copan royal lineage, was a Caracol lord. There is significant and convincing evidence that K'inich Yak K'uk Mo' had a non-Copanec origin. Stable isotope analysis is a tested and reliable method for detailing diets and migratory paths of ancient humans and this theory is applied as a predictor of the stable isotope measures of K'inich Yax K'uk Mo', if he did in fact originate in Caracol. The literature is rich with explanations of stable isotopes and the writings of a few stalwarts in the field were utilized to gain an understanding of the associated technologies and techniques utilized in its analysis. Data from the Copan (Whittington and Reed 1997) and Caracol (Chase and Chase 2001) stable isotope studies were utilized to show the application of stable isotope analysis in areas "associated" with K'inich Yax K'uk Mo' and to illustrate how the palace diet identified by Chase and Chase (2001; Chase et al. 2001) could be aligned with the Stuart hypothesis to predict the stable isotope ranges for K'inich Yax K'uk Mo'.ID: 030423403; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (M.A.)--University of Central Florida, 2011.; Includes bibliographical references (p. 72-79).
M.A.
Masters
Anthropology
Sciences
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Gunaratnam, Bakeerathan. "TOPICS IN STOCHASTICS AND STATISTICS: SHOCK CREATION AND DISSOLUTION FOR STABLE AND LINNIK CONSERVATION LAWS AND TARGET STUDENT RECRUITMENT USING PREDICTIVE MODELING." Case Western Reserve University School of Graduate Studies / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=case1363709622.
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Švéda, Jaroslav. "Nalezení pozice stanic v Internetu pomocí umělých souřadnicových systémů." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2009. http://www.nusl.cz/ntk/nusl-218001.
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This thesis deals with predicting the latency between two network nodes, such as the two stations, two servers or server and station. The main reason for adoption of effective latency prediction techniques is the elimination of network load caused by unnecessary repeated transmissios or by direct measurement of the latency. Of the many proposed methods of latency estimation, this thesis is focused on methods using artificial coordinate systems with primary focus on the Vivaldi algorithm. Characteristics of the latency prediction methods and properties of various coordinate systems used in practice are evaluated. The issue of the number of dimensions of space defined only by the latency matrix between nodes is also mentioned. Furthermore, some other systems, based on logical clustering of nearby nodes, are mentioned. Description of simulation software VivaldiMonitor developed as part of the thesis is included. The primary purpose is analysis of the behavior of overlay networks implementing Vivaldi algorithm with less than a few hundred nodes. The Vivaldi algorithm is assessed by several simulations carried out using the aforementioned software.
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Li, Yuan. "Computational Methods for Analyzing RNA Folding Landscapes and its Applications." Doctoral diss., University of Central Florida, 2012. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5400.
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Non-protein-coding RNAs play critical regulatory roles in cellular life. Many ncRNAs fold into specific structures in order to perform their biological functions. Some of the RNAs, such as riboswitches, can even fold into alternative structural conformations in order to participate in different biological processes. In addition, these RNAs can transit dynamically between different functional structures along folding pathways on their energy landscapes. These alternative functional structures are usually energetically favored and are stable in their local energy landscapes. Moreover, conformational transitions between any pair of alternate structures usually involve high energy barriers, such that RNAs can become kinetically trapped by these stable and local optimal structures. We have proposed a suite of computational approaches for analyzing and discovering regulatory RNAs through studying folding pathways, alternative structures and energy landscapes associated with conformational transitions of regulatory RNAs. First, we developed an approach, RNAEAPath, which can predict low-barrier folding pathways between two conformational structures of a single RNA molecule. Using RNAEAPath, we can analyze folding pathways between two functional RNA structures, and therefore study the mechanism behind RNA functional transitions from a thermodynamic perspective. Second, we introduced an approach, RNASLOpt, for finding all the stable and local optimal structures on the energy landscape of a single RNA molecule. We can use the generated stable and local optimal structures to represent the RNA energy landscape in a compact manner. In addition, we applied RNASLOpt to several known riboswitches and predicted their alternate functional structures accurately. Third, we integrated a comparative approach with RNASLOpt, and developed RNAConSLOpt, which can find all the consensus stable and local optimal structures that are conserved among a set of homologous regulatory RNAs. We can use RNAConSLOpt to predict alternate functional structures for regulatory RNA families. Finally, we have proposed a pipeline making use of RNAConSLOpt to computationally discover novel riboswitches in bacterial genomes. An application of the proposed pipeline to a set of bacteria in Bacillus genus results in the re-discovery of many known riboswitches, and the detection of several novel putative riboswitch elements.ID: 031001558; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Adviser: Shaojie Zhang.; Title from PDF title page (viewed August 26, 2013).; Thesis (Ph.D.)--University of Central Florida, 2012.; Includes bibliographical references (p. 132-140).
Ph.D.
Doctorate
Computer Science
Engineering and Computer Science
Computer Science
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Škvor, Martin. "Lokalizace stanic v síti Internet pomocí umělých souřadnicových systémů." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2010. http://www.nusl.cz/ntk/nusl-218229.
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This thesis is focused on methods for nodes localization in Internet using latency prediction in synthetic coordinates systems. Thesis also deal with methods, which latency prediction between nodes is based on other systems. Among such a methods particularly belongs King, which uses DNS (domain name service). Furthermore, thesis deal with relevance of overlay networks in latency prediction and their use for different services. Practical part of this thesis concentrates on method for latency prediction in synthetic coordinate system Global Network positioning. There were made two programs for counting coordinates of landmarks and hosts in this system. Measurements and calculations made in this thesis, are focused to determine accuracy of latency prediction of this method and their evaluation is made at the end of thesis.
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Kahaei, Mohammad Hossein. "Performance analysis of adaptive lattice filters for FM signals and alpha-stable processes." Thesis, Queensland University of Technology, 1998. https://eprints.qut.edu.au/36044/7/36044_Digitised_Thesis.pdf.
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The performance of an adaptive filter may be studied through the behaviour
of the optimal and adaptive coefficients in a given environment. This thesis
investigates the performance of finite impulse response adaptive lattice filters for
two classes of input signals: (a) frequency modulated signals with polynomial
phases of order p in complex Gaussian white noise (as nonstationary signals),
and (b) the impulsive autoregressive processes with alpha-stable distributions (as
non-Gaussian signals).
Initially, an overview is given for linear prediction and adaptive filtering. The
convergence and tracking properties of the stochastic gradient algorithms are discussed
for stationary and nonstationary input signals. It is explained that the
stochastic gradient lattice algorithm has many advantages over the least-mean
square algorithm. Some of these advantages are having a modular structure,
easy-guaranteed stability, less sensitivity to the eigenvalue spread of the input autocorrelation
matrix, and easy quantization of filter coefficients (normally called
reflection coefficients).
We then characterize the performance of the stochastic gradient lattice algorithm
for the frequency modulated signals through the optimal and adaptive
lattice reflection coefficients. This is a difficult task due to the nonlinear dependence
of the adaptive reflection coefficients on the preceding stages and the input
signal. To ease the derivations, we assume that reflection coefficients of each
stage are independent of the inputs to that stage. Then the optimal lattice filter
is derived for the frequency modulated signals. This is performed by computing
the optimal values of residual errors, reflection coefficients, and recovery errors.
Next, we show the tracking behaviour of adaptive reflection coefficients for
frequency modulated signals. This is carried out by computing the tracking model
of these coefficients for the stochastic gradient lattice algorithm in average. The
second-order convergence of the adaptive coefficients is investigated by modeling
the theoretical asymptotic variance of the gradient noise at each stage. The
accuracy of the analytical results is verified by computer simulations.
Using the previous analytical results, we show a new property, the polynomial
order reducing property of adaptive lattice filters. This property may be used to
reduce the order of the polynomial phase of input frequency modulated signals.
Considering two examples, we show how this property may be used in processing
frequency modulated signals. In the first example, a detection procedure in carried
out on a frequency modulated signal with a second-order polynomial phase
in complex Gaussian white noise. We showed that using this technique a better
probability of detection is obtained for the reduced-order phase signals compared
to that of the traditional energy detector. Also, it is empirically shown that
the distribution of the gradient noise in the first adaptive reflection coefficients
approximates the Gaussian law. In the second example, the instantaneous frequency
of the same observed signal is estimated. We show that by using this
technique a lower mean square error is achieved for the estimated frequencies at
high signal-to-noise ratios in comparison to that of the adaptive line enhancer.
The performance of adaptive lattice filters is then investigated for the second
type of input signals, i.e., impulsive autoregressive processes with alpha-stable
distributions . The concept of alpha-stable distributions is first introduced. We
discuss that the stochastic gradient algorithm which performs desirable results
for finite variance input signals (like frequency modulated signals in noise) does
not perform a fast convergence for infinite variance stable processes (due to using
the minimum mean-square error criterion). To deal with such problems, the
concept of minimum dispersion criterion, fractional lower order moments, and
recently-developed algorithms for stable processes are introduced.
We then study the possibility of using the lattice structure for impulsive stable
processes. Accordingly, two new algorithms including the least-mean P-norm
lattice algorithm and its normalized version are proposed for lattice filters based
on the fractional lower order moments. Simulation results show that using the
proposed algorithms, faster convergence speeds are achieved for parameters estimation
of autoregressive stable processes with low to moderate degrees of impulsiveness
in comparison to many other algorithms. Also, we discuss the effect of
impulsiveness of stable processes on generating some misalignment between the
estimated parameters and the true values. Due to the infinite variance of stable
processes, the performance of the proposed algorithms is only investigated using
extensive computer simulations.
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Brogno, Luigi. "Nocturnal low-level jets over complex terrain: driving mechanisms and analytical modeling." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amslaurea.unibo.it/20539/.
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Several studies in the Atmospheric Physics have focused on the analysis of the atmospheric circulation phenomena at the small scale and turbulent processes within the planetary boundary layer (PBL), whose formation and evolution is complicated by the topography.
The Low-Level Jet (LLJ) is one of the most studied phenomena and it is not yet completely understood. It consists in the occurrence of strong winds within a thin layer of the PBL.
A particular case is the formation of double-nose LLJs (or multiple LLJs), i.e. the simultaneous occurrence of two (or multiple) noses within the PBL.
Analysing data retrieved in complex terrain during the MATERHORN field campaigns, the objectives of this thesis are to understand the mechanisms which drive the formation of the double-nose LLJs identified using a newly-proposed criterion that upgrade the already existing ones.
The new identification criterion is used to analyse quiescent Intensive Observing Periods (IOPs), in which nocturnal stable boundary-layer conditions and local thermal circulation are not altered or driven by synoptic forcing.
During these IOPs, the formation of a LLJ due to inertial oscillations is typical few hours after the sunset.
However, the LLJ structure can be temporary perturbed generating a double-nose LLJ.
Two double-nose LLJ driving mechanisms are identified.
The wind-driven mechanism is when the two noses are associated with different air masses flowing one on top of the other.
The wave-driven mechanism is when a surface perturbation generates an inertial-gravity wave which transports momentum during its propagation.
Momentum is lost by the LLJ nose and transported upward where a second one is generated.
Furthermore, the evolution of the LLJs driven by the inertial oscillations is investigated by means of two models retrieved from the literature.
The models provides similar representation of the observed LLJs, concluding that the LLJs are well simulated when they are fully developed.
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Balzotti, Christopher Stephen. "Multidisciplinary Assessment and Documentation of Past and Present Human Impacts on the Neotropical Forests of Petén, Guatemala." BYU ScholarsArchive, 2010. https://scholarsarchive.byu.edu/etd/2129.
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Tropical forests provide important habitat for a tremendous diversity of plant and animal species. However, limitations in measuring and monitoring the structure and function of tropical forests has caused these systems to remain poorly understood. Remote-sensing technology has provided a powerful tool for quantification of structural patterns and associating these with resource use. Satellite and aerial platforms can be used to collect remotely sensed images of tropical forests that can be applied to ecological research and management. Chapter 1 of this article highlights the resources available for tropical forest remote sensing and presents a case-study that demonstrates its application to a neotropical forest located in the Petén region of northern Guatemala. The ancient polity of Tikal has been extensively studied by archaeologists and soil scientists, but little is known about the subsistence and ancient farming techniques that sustained its inhabitants. The objective of chapter 2 was to create predictive models for ancient maize (Zea mays L.) agriculture in the Tikal National Park, Petén, Guatemala, improving our understanding of settlement patterns and the ecological potentials surrounding the site in a cost effective manner. Ancient maize agriculture was described in this study as carbon (C) isotopic signatures left in the soil humin fraction. Probability models predicting C isotopic enrichment and carbonate C were used to outline areas of potential long term maize agriculture. It was found that the Tikal area not only supports a great variety of potential food production systems but the models suggest multiple maize agricultural practices were used.
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Amey, Katherine Springer. "Hydrology And Predictive Model Of Headwater Streams And The Groundwater/Surface Water Interactions Supporting Brook Trout Habitat In Northeast Ohio." Kent State University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=kent1301618586.
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Grecian, William James. "Factors influencing the marine spatial ecology of seabirds : implications for theory, conservation and management." Thesis, University of Plymouth, 2011. http://hdl.handle.net/10026.1/873.
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Seabirds are wide-ranging apex-predators and useful bio-indicators of marine systems. Nevertheless, changes are occurring in the marine environment, and seabirds require protection from the deleterious effects of climate change, fisheries, pollution, offshore development, introduced predators and invasive species. The UK supports internationally important populations of seabirds but also has vast wind and wave resources, therefore understanding how seabirds use the marine environment is vital in order to quantify the potential consequences of further exploiting these resources. In this thesis I first describe the range of wave energy converting devices operational or in development in the UK, and review the potential threats and benefits these developments may have for marine birds. I then synthesise data from colony-based surveys with detailed information on population dynamics, foraging ecology and near-colony behaviour, to develop a projection model that identifies important at-sea areas for breeding seabirds. These models show a positive spatial correlation with one of the most intensive at-sea seabird survey datasets, and provide qualitatively similar findings to existing tracking data. This approach has the potential to identify overlap with offshore energy developments, and could be developed to suit a range of species or whole communities and provide a theoretical framework for the study of factors such as colony size regulation. The non-breeding period is a key element of the annual cycle of seabirds and conditions experienced during one season may carry-over to influence the next. Understanding behaviour throughout the annual cycle has implications for both ecological theory and conservation. Bio-logging can provide detailed information on movements away from breeding colonies, and the analysis of stable isotope ratios in body tissues can provide information on foraging during the non-breeding period. I combine these two approaches to describe the migration strategies of northern gannets Morus bassanus breeding at two colonies in the north-west Atlantic, revealing a high degree of both winter site fidelity and dietary consistency between years. These migratory strategies also have carry-over effects with consequences for both body condition and timing of arrival on the breeding grounds. Finally, I investigate the threats posed to seabirds and other marine predators during the non-breeding period by collating information on the distributions of five different species of apex predator wintering in the Northwest African upwelling region. I describe the threat of over-fishing and fisheries bycatch to marine vertebrates in this region, and highlight the need for pelagic marine protected areas to adequately protect migratory animals throughout the annual cycle. In summary, the combination of colony-based studies, bio-logging, stable isotope analysis and modelling techniques can provide a comprehensive understanding of the interactions between individuals and the marine environment over multiple spatial and temporal scales.
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(7460849), Aldo Fabrizio Porco. "USING MODULAR ARCHITECTURES TO PREDICT CHANGE OF BELIEFS IN ONLINE DEBATES." Thesis, 2019.
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Researchers studying persuasion have mostly focused on modeling arguments to understand how people’s beliefs can change. However, in order to convince an audience the speakers usually adapt their speech. This can be seen often in political campaigns when ideas are phrased - framed - in different ways according to the geo-graphical region the candidate is in. This practice suggests that, in order to change people’s beliefs, it is important to take into account their previous perspectives and topics of interest.
In this work we propose ChangeMyStance, a novel task to predict if a user would change their mind after being exposed to opposing views on a particular subject. This setting takes into account users’ beliefs before a debate, thus modeling their preconceived notions about the topic. Moreover, we explore a new approach to solve the problem, where the task is decomposed into ”simpler” problems. Breaking the main objective into several tasks allows to build expert modules that combined produce better results. This strategy significantly outperforms a BERT end-to-end model over the same inputs.
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Stanke, Mario [Verfasser]. "Gene prediction with a hidden Markov model / vorgelegt von Mario Stanke." 2004. http://d-nb.info/970841310/34.
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Oesting, Marco. "Spatial Interpolation and Prediction of Gaussian and Max-Stable Processes." Doctoral thesis, 2012. http://hdl.handle.net/11858/00-1735-0000-000D-F069-0.
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Ti-ChenYeh and 葉廸珺. "Establishing A Stable and Loyal Customers Prediction Model with Bootstrap." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/7ks9c9.
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Hofacker, I. L., B. Priwitzer, and P. F. Stadler. "Prediction of locally stable RNA secondary structures for genome-wide surveys." 2004. https://ul.qucosa.de/id/qucosa%3A32116.
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Motivation: Recently novel classes of functional RNAs, most prominently the miRNAs have been discovered, strongly suggesting that further types of functional RNAs are still hidden in the recently completed genomic DNA sequences. Only few techniques are known, however, to survey genomes for such RNA genes. When sufficiently similar sequences are not available for comparative approaches the only known remedy is to search directly for structural features.
Results: We present here efficient algorithms for computing locally stable RNA structures at genome-wide scales. Both the minimum energy structure and the complete matrix of base pairing probabilities can be computed in 𝒪(N × L2) time and 𝒪(N + L2) memory in terms of the length N of the genome and the size L of the largest secondary structure motifs of interest. In practice, the 100 Mb of the complete genome of Caenorhabditis elegans can be folded within about half a day on a modern PC with a search depth of L = 100. This is sufficient example for a survey for miRNAs.
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Tung, Chi-Feng, and 董其豐. "Mobility Prediction-Based Relay Selection Scheme for Stable Connections in VANETs." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/05103792050876499135.
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碩士國立中央大學
資訊工程研究所
99
Vehicular ad hoc network (VANET) is a novel class of wireless network. Vehicles implemented with on board unit (OBU), which can communicate with each other by vehicle-to-vehicle (V2V) and vehicle to infrastructure (V2R) network architecture. In the V2V network environment, vehicular network topology is changing dynamically all the time with high mobility, the communications occurred in this architecture is intermittent pattern. To solve this problem, numerous researchers have proposed different kinds of VANET routing protocol to enhance the success of packets delivery ratio through choosing the path with high density. After determining the routing path, the choosing of relay nodes usually follow the mobile ad hoc networks (MANETs) routing protocol, that is, it selects the closest node with the destination or consider the power supply and computation ability of node. However, In MANET, mobile nodes are moving in a random and irregular pattern hence, it is very hard to predict their movements. Unlike unpredictable mobility in MANET, vehicles are limited by predefined road segments, traffic rules and driver behaviors. Furthermore, nowadays Vehicular on board units are able to equip a much more powerful vehicle rechargeable battery and a larger volume of communication device than before; therefore, it becomes inappropriate to take power supply volume and computing into account. Therefore, it is unsuitable to determine the relay node by these terms. What’s more important is that the vehicle moves too fast to make the relay node easily to leave the transmission range of sender, as a result, it wastes a lot of network bandwidth for route maintenance and re-discovery. In order to solve the above mentioned problems, this thesis proposed a mobility prediction-based relay selection scheme for stable connections in VANETs which takes both direction of vehicles and routing path into account. It makes packet routing and vehicles keep moving in the same direction, for reducing the link disconnection. This thesis takes GPS errors into consideration when determining the lane position to predict the vehicles mobility, for a even more accurate mobility prediction. Finally, the proposal is examined by the conducted simulation— the simulation results show that the proposed mechanism, on average, can increase connecting time by 25.6% but decrease number of link disconnection by 20.2%; furthermore, the prediction accuracy of connecting time is improved within the absolute error of 5.09%. This proves that in the multi-lanes scenarios, the proposed mechanism can provide even more stable connecting time than others.
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Wu, De-Wei, and 武德偉. "Prediction of stable limit cycles in feedback bilinear systems:Bellman-Gronwall Inequality." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/53987709200160653334.
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碩士義守大學
電機工程學系
91
Limit cycles are unique phenomenon of nonlinear networks and have been a main concern of the researchers over the years. Prediction of limit cycles is very significant, because limit cycles can happen in any kind of physical system. In this thesis, the existence of limit cycles for a class of feedback bilinear systems is explored. Using the Bellman-Gronwall inequality, not only the exponentially stable limit cycles phenomenon of such systems can be guaranteed but also the oscillation behaviors of such systems can be correctly predicted. Finally, some numerical examples is provided to illustrate the use of the main result.
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Ralhan, Sameer. "Robust model predictive control of stable and integrating linear systems." Thesis, 2000. http://hdl.handle.net/1911/19549.
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Model Predictive Control (MPC) has become one of the dominant methods of chemical process control in terms of successful industrial applications. A rich theory has been developed to study the closed loop stability of MPC algorithms when the plant model is perfect, referred to as the nominal stability problem. In practical applications, however, the process model is never perfect and nominal stability results are not strictly applicable. The primary disadvantage of the current MPC design techniques is their inability to deal explicitly with the plant model uncertainty.
In this thesis we develop a new framework for robust MPC synthesis that allows explicit incorporation of the plant uncertainty description in the problem formulation. The robust stability results are developed for general uncertainty descriptions. Hard input and soft output constraints can be easily added to the algorithms without affecting closed loop stability.
Robust stability is achieved through the addition of constraints that prevent the sequence of the optimal controller costs from increasing for the true plant. These cost function constraints can be solved analytically for the special case of bounded input matrix uncertainty. The closed loop system also remains stable in the face of asymptotically decaying disturbances.
The framework developed for bounded input matrix uncertainty for stable plants can also be used for integrating plants. Two formulations are developed; a single stage optimization method that minimizes the state error at the end of the horizon, and a two stage optimization method which minimizes the state error at the end of the horizon in the first stage but uses the remaining degrees in a second stage to minimize state deviations over the full prediction horizon. Hard input and soft output constraints can be easily added to the algorithms without affecting the closed loop stability.
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CHANG, YA-LING, and 張雅羚. "Adaptive Stable Generalized Predictive Temperature Control for Air Conditioning System." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/52338199575334726641.
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碩士國立中興大學
電機工程學系
91
This thesis aims at developing methodologies and techniques for adaptive stable generalized predictive control of small air conditioning systems. Such techniques are used to control the rotational speed of pump of ice-water machine of small air-condition system with air-cooling, thereby adjusting the rate of heat exchange for the cold store in a refrigerated circulatory system in order to accomplish temperature set-point tracking. To achieve satisfactory temperature control performance, two predictive control strategies, adaptive stable generalized predictive control and adaptive stable generalized predictive control with fuzzy modeling, are proposed. Computer simulations for several industrial processes and experimental results of temperature control in the air-condition system show that both the two proposed control methods have been proven to be capable of stability, disturbance rejection capability and good tracking performance.
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葉雲碩. "Stable Predictive Control for an AC Induction Motor-Driven Servo System." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/76690187743309866281.
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碩士國立中興大學
機械工程學系
92
This thesis considers the system identification and infinite horizon stable predictive control (IHSPC) design for an AC induction motor-driven servo system. The RLS (recursive least squares) algorithm is used for obtaining the optimal parameters of a discrete-time linear estimation model with a constant bias term. Based on the estimated model, the IHSPC design methodology is adopted for synthesizing a stable predictive control law for the actual servo system. Finally, the control law is developed in the MATLAB/SIMULINK environment and implemented using a dSPACE DS1102 control board. Experimental results validate the feasibility of the suggested approach.
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Liu, Shu Chen, and 劉淑貞. "The Stable Regions of Multi-Block Predictor-Corrector Method for ODE's." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/75407656621700670775.
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碩士國立中正大學
數學研究所
91
The multi-block predictor-corrector method(BPC) is one of the efficient and accurate method for solving the numerical solution of the ordinary differential equations. By choosing some suitable matrix coefficients in two schemes with repeated self-correcting processes, P(EC)^nE,n=1,2,...,we investigate and compare the corresponging changes of the stable regions. We also vary the coefficients matrix in the local truncation error to study the responses about the stable respectively.
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Lin, Shu-Kai, and 林書楷. "Unified Predictive Control Applied to Stable First-Order-Plus-Dead-Time Processes." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/66639704776612243853.
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碩士國立交通大學
機械工程學系
98
In the field of the motion control, dead-time process with model uncertainty and disturbance are widely studied because of the practical importance. This thesis is divided into two parts to deal with these problems, respectively; Part I (based on the concept of robust control): One applies Unified Predictive Control (UPC) to first-order-plus-dead-time (FOPDT) stable processes with concerns of model uncertainty and deterministic disturbance, and analyzed the robustness and nominal performance of the system. A simple and useful parameter tuning method is proposed. The results of this part guarantees optimal nominal performance based on robust stable condition. Part II (based on the concept of adaptive control): one proposes an Adaptive Unified Predictive Control (Adaptive-UPC) and applied it to first-order-plus-dead-time (FOPDT) process model to eliminate effects of model uncertainties and unknown deterministic disturbance. This new control structure is designed based on one of the concepts of adaptive control, Indirect Self-tuning Regulator, and constructed by combining UPC controller, Recursive Least-Squares Estimation with forgetting factor (RLS with forgetting factor) and Variable Regression Estimation (VRE). The results of this part can be effectively used to first-order-plus-dead-time (FOPDT) process models and can accurately estimate the process parameters (gain, time constant and dead-time) with elimination of unknown deterministic disturbance. For practical purpose, the problem of measurement noise must be concerned. Therefore the Modified Adaptive Unified Predictive Control (Modified Adaptive-UPC) is proposed to decrease the effect caused by measurement noise.
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ZHU, MU-FENG, and 朱穆鳳. "On stable algorithm of block predictor-corrtctor method for five-CPU computers." Thesis, 1992. http://ndltd.ncl.edu.tw/handle/90819929001981379027.
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Adnan, Adnan. "Evaluation of near infrared spectroscopy for prediction of quality attributes and authentication of green coffee beans." Doctoral thesis, 2017. http://hdl.handle.net/21.11130/00-1735-0000-0005-14B3-A.
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Oliveira, Henrique Martim Aguiar Sobral. "Bitcoin price movement direction prediction : a comparison between Decision Tree SVM and LSTM." Master's thesis, 2021. http://hdl.handle.net/10400.14/35339.
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This thesis explores the ability of machine learning methods combined with the use of blockchain characteristics, a stable coin proxy and technical indicators to predict the price movement of Bitcoin correctly. The experimental work attempts to prove that machine learning models can outperform a Buy & Hold strategy with the selected features and compares the classification performance of Decision Tree, a Support Vector Machine and a Long Short-Term Memory Recurrent Neural Network. The results from the feature selection supported the findings of existing literature. Additionally, the results suggest that mining difficulty and blockchain characteristics that measure transaction activity can provide supplementary information about Bitcoin. In terms of the performance of the models, results showed that a Decision Tree model has the propensity to overfit due to its low complexity and the type of data. The results from the SVM showed that although it achieved the highest accuracy, it only managed to identify the overall trend and therefore it was not able to beat a Buy & Hold strategy. Even though the LSTM did not outperform the benchmarks, it was the model that showed the most promising results, and its performance would likely improve by additional hyperparameter tunning. Therefore, the inability to outperform the benchmarks was not conclusive. Finally, the fact that the Logistic regression model was able to outperform the Buy & Hold strategy in terms of returns and volatility leads us to conclude that machine learning methods might be effective in predicting bitcoin price movement with the selected features.Esta tese explora a capacidade dos métodos de machine learning em conjunto com o uso de características da blockchain, um proxy de stable coins e indicadores técnicos para prever corretamente o movimento do preço da Bitcoin. Esta tese tenta provar que modelos de machine learning podem superar uma estratégia Buy & Hold com as variáveis selecionadas e compara o desempenho de uma árvore de decisão, uma SVM e uma rede neural recorrente LSTM. Os resultados da seleção de variáveis apoiam a literatura existente. Além disso, os resultados também sugerem que a dificuldade de mineração e características do blockchain relacionadas com atividade transacional podem fornecer informações complementares sobre a Bitcoin. Em termos de desempenho dos modelos, os resultados mostraram que o modelo de árvore de decisão tem predisposição para sobre ajustar devido à sua baixa complexidade e ao tipo de dados. Os resultados do SVM mostraram que, embora tenha alcançado a maior precisão, apenas conseguiu identificar a tendência geral e, portanto, não foi capaz de superar a estratégia Buy & Hold. Mesmo que o LSTM não tenha superado os benchmarks, foi o modelo que mostrou os resultados mais promissores, e seu desempenho provavelmente melhoraria realizando ajuste adicional dos híper-parâmetros. Logo, a incapacidade de superar o benchmark não foi conclusivo. Finalmente, o facto de o modelo de regressão logística ter sido capaz de superar a estratégia Buy & Hold em termos de retornos e volatilidade, leva-nos a concluir que machine learning pode ser eficaz na previsão da Bitcoin com as variáveis selecionadas.
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Chang, Chih-Peng, and 張志鵬. "Control of stable and integrating processes with dead-time based on PDOB and Smith predictor structure." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/10971257948311630919.
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碩士國立交通大學
機械工程系所
98
Significantly the dead-time has a great influence on the stability of systems, which make the process more difficult to control. Therefore, this thesis presents a discrete dead-time compensator to improve the performance and capability of disturbance rejection for dead-time systems. It applied predictive DOB and Smith predictor structure to compensate output delay and input disturbance for stable and integrating plants. The proposed structure consists of two parts: the inner loop and the outer loop. Firstly the PDOB can be designed to reject any kind of deterministic disturbances, including step disturbance, ramp disturbance and sine disturbance. Also, the property of DOB structure can approach the real plant to the nominal plant. The PDOB based on DOB structure has an additional predictive filter, which eliminate the time delay of estimated disturbance. Because of the property enhances disturbance rejection performance of traditional DOB for dead-time systems especially for periodic disturbance. Secondly, the Smith predictor structure is capable to suppress the effects of time delay. Seeing that the stability is influenced by the model mismatch and model mismatch will always exist in the process. In this thesis, we propose a robust controller which compensates the effect of time delay and reject deterministic disturbance to satisfy the robust stability.
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Bade, Darren Lee. "Predicting stable isotope signatures of dissolved inorganic carbon in lakes models to aid in the understanding of carbon cycling across many lakes /." 2002. http://catalog.hathitrust.org/api/volumes/oclc/51552605.html.
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Thesis (M.S.)--University of Wisconsin--Madison, 2002.Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 26-31).
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Schauble, Edwin Arthur. "I. Predicting equilibrium stable isotope fractionations of iron, chlorine, and chromium. II. Oxygen-isotope investigation of mesozoic and cenozoic granitoids of the northeastern Great Basin, Nevada and Utah." Thesis, 2002. https://thesis.library.caltech.edu/6899/1/Schauble_ea_2002.pdf.
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Theoretical studies of the stable isotope geochemistry of iron, chlorine, and chromium are presented, with the goal of providing a framework to aid interpretations of new measurements and to identify promising areas for future study. In addition, new oxygen-isotope measurements of Mesozoic and Cenozoic granitoids from the northeastern Great Basin are used to constrain the temporal evolution of magmatic sources in the region.
The stable isotope compositions of elements heavier than sulfur (atomic no. 16) are generating great geochemical interest, now that new mass-spectrometry techniques make it possible to measure their isotopic abundances with high precision. Theoretical calculations for three of these elements (iron, chlorine, and chromium) are made using published infrared, Raman, and inelastic neutron scattering measurements of vibrational frequencies, in combination with empirical and ab initio force-field estimates of unknown frequencies. The calculations suggest that a number of natural processes can drive significant stable isotope fractionations of heavy elements, including oxidation/reduction during the precipitation or dissolution of dissolved metals (inorganically or organically), and bond-partner exchange during hydrothermal alteration, or degradation of Cl-bearing organic compounds. At equilibrium and 25°C, ^(56)Fe/^(54)Fe will be ~5‰ higher in [Fe(H_2O)_6]^(3+) than in coexisting [Fe(H_2O)_6]^(2+), ^(53)Cr/^(52)Cr will be ~6-7‰ higher in [CrO_4]^(2-) than in coexisting [Cr(H_2O)_6]^(3+) or Cr_2O_3, and aqueous Cl- will be ~2-3‰ lighter than coexisting alteration minerals like mica and amphibole.
Oxygen isotope measurements of whole-rock samples from granitoid plutons in the northeastern Great Basin suggest that two or three different types of source rocks were melted in varying proportions during the three stages of magmatism in this region in the Late Jurassic, Late Cretaceous, and mid-Cenozoic. Radiogenic-isotope measurements were previously made on the same samples. Late Cretaceous (90-70 Ma) granites have high δ^(18)O (+9.3 to + 12.1) and ^(87)Sr/^(86)Sr_i (0.711 to 0.734), and low εNd (-13 to -23) indicating that their source was dominated by evolved crustal sediments and basement. However, late Jurassic plutons in this region span a larger range of δ^(18)O values (+7.2 to + 13.2), despite having Sr and Nd isotopic compositions that are much less suggestive of an ancient crustal component (^(87)Sr/^(86)Sr_i = 0.705 to 0.711, εNd = -2.5 to -6.5) than the Late Cretaceous plutons, suggesting moderate to extensive mixing or assimilation of high-δ^(18)O sedimentary rocks into a more mafic parent melt. The 40-25 Ma Cenozoic plutons (δ^(18)O = +7.0 to + 9.7, ^(87)Sr/^(86)Sr_i = 0.707 to 0.717, εNd= -13.2 to -26.3) probably have a source dominated by continental basement. The Cenozoic plutons can be subdivided into a higher δ^(18)O (+8.6 to + 9.7) southern group and a lower δ^(18)O (+7.0 to + 8.2) northern group across a Crustal Age Boundary (CAB) at roughly 40° 40' N; this CAB coincides with a radiogenic isotope boundary defined with the same samples, as well as with the approximate southern limit of exposure of Archean basement. The low δ^(18)O values and depleted lead isotope compositions of the Lower Array (northern) samples indicate that Archean age basement is present beneath a large area of the most northeasterly part of the Great Basin. A further, speculative conclusion is that δ^(18)O of the (meta)sedimentary source region may have dropped by 2-3‰ as a result of fluid-rock interaction sometime between the Jurassic and Late Cretaceous magmatic episodes.
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Cuinala, Hildair Panfílio Mendes de Carvalho. "Previsão numérica da vida à fadiga em peças entalhadas sujeitas a cargas cíclicas multiaxiais." Master's thesis, 2019. http://hdl.handle.net/10316/93623.
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Dissertação de Mestrado Integrado em Engenharia Mecânica apresentada à Faculdade de Ciências e TecnologiaA fadiga é na grande maioria das vezes a razão associada a ruína dos componentes mecânicos solicitados ciclicamente. Este fenómeno é fortemente influenciado por várias propriedades, das quais destacamos a geometria do material solicitado e o tipo de carregamento aplicado. Quanto maior for a descontinuidade geométrica apresentada no material maior a sua sensibilidade ao fenómeno de fadiga.Atualmente a grande maioria dos componentes mecânicos utilizados nas transmissões mecânicas, apresentam várias descontinuidades geométricas severas e estão sujeitos a carregamentos combinados e cíclicos, implicando elevada sensibilidade a falha por fadiga. Salientamos que muitas das vezes é inevitável a presença das descontinuidades geométricas, uma vez que, podem nascer por necessidades de projeto, por questões funcionais, ambientais ou orçamentais.Visando os aspetos listados no parágrafo anterior, neste estudo pretendemos desenvolver uma metodologia de previsão de vida à fadiga para peças de secção circular sujeitas a histórias de cargas multiaxiais. Para tal utilizamos a liga de aço martensítico de alta resistência DIN 34CrNiMo6, que apresenta elevada ductilidade e tenacidade, bem como tem grande destaque no sector automóvel e aeronáutico. Não podemos deixar de referir, que quanto maior a complexidade do carregamento aplicado, maior é a dificuldade do método em prever a falha por fadiga, o que torna o estudo bastante elaborado pois estamos presentes a carregamentos proporcionais multiaxiais, considerados para duas relações entre momento fletor (B) e momento torsor (T), (B=2T e B=T) e três ângulos de aplicação do momento fletor relativamente à raiz do entalhe (0º, 45º e 90º).O estudo procedeu-se em três fases, sendo que na primeira fase determinamos os estados de tensão e de deformação nas zonas críticas das descontinuidades geométricas, obtidos a partir de modelos numéricos elasto-plásticos. Nesta fase foi estimada a vida de fadiga usando o modelo energético de Ellyin e que posteriormente foi comparada com os resultados obtidos em trabalhos anteriores pelo método de Glinka.Numa segunda fase, as previsões numéricas foram comparadas com resultados experimentais, de fadiga oligocíclica, obtidos para as mesmas condições de serviço.Por fim, fizemos uma análise dos resultados apurados para cada modelo de previsão e repararmos que os mesmos são satisfatórios, pois 88,9% dos resultados encontram-se no regime conservativo e os que não estão dentro desta zona estão localizados nos intervalos de dispersão propostos.
Fatigue is most often the reason associated with the failure of cyclically ordered mechanical components. This phenomenon is strongly influenced by several properties, of which we highlight the geometry of the material requested and the type of loading applied. The greater the geometric discontinuity presented in the material, the greater its sensitivity to the phenomenon of fatigue.Currently, the vast majority of mechanical components used in mechanical transmissions have several severe geometric discontinuities and are subject to combined and cyclic loading, implying high sensitivity to fatigue failure. We emphasize that often the presence of geometric discontinuities is inevitable since they can be born due to project needs, functional, environmental or budgetary issues.Aiming at the aspects listed in the previous paragraph, in this study we intend to develop a fatigue life prediction methodology for circular section parts subjected to multiaxial load histories. For this, we use the high strength martensitic alloy steel DIN 34CrNiMo6, which high ductility and toughness, as well as being prominent in the automotive and aeronautics sector. We can not fail to mention that the greater the complexity of loading applied, the greater the difficulty of the method to predict fatigue failure, which makes the study quite elaborate because we are present with multiaxial proportional loads, considered for two relationships between bending moment. (B) and torsional moment (T), (B = 2T and B = T) and three angles of application of the bending moment relative to the notch root (0º, 45º and 90º).The study proceeded in three phases, and in the first phase we determined the stress and strain states in the critical zones of geometric discontinuities, obtained from elastoplastic numerical models. In this phase, the fatigue life was estimated using the Ellyin energy model and later compared with the results obtained in previous works by the Glinka method.In the second phase, the numerical predictions were compared with experimental oligocyclic fatigue results obtained for the same service conditions.Finally, we made an analysis of the results obtained for each prediction model and noticed that they are satisfactory because 88.9% of the results are in the conservative regime and those that are not within this zone are located in the proposed dispersion intervals.
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Van, der Walt Koert Nicolaas. "Selected anthropometric, physical and motor performance predictors of lower body explosive power in adolescents : the PAHL study / Koert Nicolaas van der Walt." Thesis, 2014. http://hdl.handle.net/10394/12207.
Full textAbstract:
Lower body explosive power (LBEP) forms a critical component in any individual and team sport performance and it is therefore essential to develop a means of predicting LBEP in adolescents for early identification of future talent in various sporting codes. LBEP is frequently used by athletes during matches or competitions where explosive movements such as jumping, agility running and sprinting are required for successful performance. These movements are usually found in individual sports such as long jump and high jump as well as in team sports such as basketball, volleyball and soccer. To date not much literature is available on LBEP, especially with regard to LBEP prediction models. Furthermore, studies on adolescents are scarce and a LBEP prediction model has not yet been developed for a South African adolescent population. It is against this background that the objectives of this study were firstly, to develop a LBEP prediction model from various physical and motor performance components among a cohort of adolescents living in the Tlokwe local municipality of Dr Kenneth Kaunda district in the North-West Province, South Africa; and secondly, to develop a LBEP prediction model from several anthropometric measurements among a cohort of male and female adolescents living in the Tlokwe local municipality of Dr Kenneth Kaunda district in the North-West Province, South Africa. Two hundred and fourteen (15.8±0.68 years) 15-year-old adolescents (126 females, 88 males) from 6 surrounding schools within the Tlokwe local municipality of Dr Kenneth Kaunda district in the North-West Province of South Africa were purposefully selected from pre-acquired class lists took part in the study. Data was collected by means of various questionnaires as well as anthropometrical, physical and motor performance tests. For representation of LBEP a principal component factor analysis was done and the results indicated that the vertical jump test (VJT) was the best indicator of LBEP in the cohort of adolescents.
With regard to the anthropometrical related LBEP prediction model, the forward stepwise regression analysis yielded a correlation coefficient of R2 = 0.69. The following variables contributed significantly (p≤0.001) to the anthropometrical LBEP prediction model: stature (57%), muscle mass percentage (10%) and maturity age (3%). The LBEP prediction model that was developed equated to LBEP (vertical jump) = -136.30 + 0.84(stature) + 0.7(muscle mass percentage) + 4.6(maturity age). Variables other than the variables that formed part of the study could explain the further 31% variance in the LBEP of the adolescents. The physical and motor performance LBEP prediction model indicated that gender (39%) and 10 m speed (7%) contributed significantly (p ≤ 0.001) to the overall prediction of the LBEP of the adolescents. The LBEP prediction model delivered a stepwise forward regression analysis coefficient of R2=0.458 and a prediction formula LBEP = 68.21 + 9.82 (gender) – 18.33(10 m speed). The remaining 56% of the variance in the results could be explained by other factors than the variables considered in the study. In conclusion, to the best of the researchers’ knowledge, this is the first study which has made an attempt at developing LBEP prediction models from the anthropometrical, physical and motor performance components of a cohort of adolescents of South Africa. The prediction models developed in the study will assist teachers sport scientists and sporting coaches who have limited resources available, to measure and calculate LBEP in adolescents, with the means to do so in South Africa. Further high quality studies are necessary to further improve and develop such prediction models for various age groups of adolescents in the greater South Africa.MSc (Sport Science), North-West University, Potchefstroom Campus, 2014
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Brouillette-Alarie, Sébastien. "L’évaluation du risque de récidive des agresseurs sexuels : vers une approche centrée sur les construits psychologiques." Thèse, 2016. http://hdl.handle.net/1866/18446.
Full textAbstract:
Cette thèse a été faite sous la tutelle de Jean Proulx et R. Karl Hanson. Elle a évaluée par un jury composé de Franca Cortoni, Jean Proulx, R. Karl Hanson, Jean-Pierre Guay et Howard E. Barbaree. Suite à la soutenance, la thèse a reçu la mention "exceptionnelle", a été recommandée à la liste d'honneur du doyen et a été soumise pour le prix de la meilleure thèse de la FESP 2017.Les outils actuariels servant à évaluer le risque de récidive criminelle des agresseurs sexuels ont souvent été critiqués pour leurs fondements « athéoriques ». En effet, ces derniers ont été constitués en rassemblant les caractéristiques les plus fortement associées à la récidive, sans qu’une théorie ne les unisse à priori. Si cette méthode a assuré une bonne validité prédictive à ces instruments, elle leur a insufflé très peu de résonnance clinique; plusieurs professionnels n’y voient qu’une liste de corrélats statistiques vides de sens. La présente thèse a entrepris de relativiser ces critiques en appliquant des modèles de facteurs latents aux différents items des outils actuariels. Les modèles de facteurs latents postulent que les comportements manifestes (observables) d’un individu renseignent sur ses caractéristiques psychologiques latentes (non observables) – de la même manière que les symptômes d’une maladie permettent d’inférer sa présence chez un patient. Puisque les items des outils actuariels correspondent à divers comportements ou caractéristiques criminogènes manifestes, il devrait être possible de les rassembler en dimensions pour identifier les principaux construits psychologiques latents associés à la récidive des agresseurs sexuels. Les articles de la présente thèse ont donc proposé d’identifier les dimensions de la Statique-99R et de la Statique-2002R, la famille d’outils actuariels pour agresseurs sexuels la plus utilisée mondialement. Trois dimensions ont été extraites par analyse factorielle : 1) la persistance dans les délits sexuels/paraphilies sexuelles, 2) la délinquance générale et 3) le jeune âge/victimes sexuelles non familières. La première dimension était exclusivement associée à la récidive sexuelle, tandis que les deux dernières étaient associées à tous les types de récidives. Leur validité convergente a ensuite été explorée afin d’évaluer à quelles caractéristiques psychologiques ces dernières référaient. La persistance/paraphilie a convergé avec des indicateurs d’intérêts sexuels déviants non coercitifs, alors que la délinquance générale a convergé avec une constellation de traits antisociaux. Finalement, le jeune âge/victimes sexuelles non familières a convergé avec l’intention claire de blesser ses victimes. Ces résultats ont mené au développement d’un modèle tridimensionnel du risque de récidive des agresseurs sexuels ayant plusieurs implications pratiques pour le domaine. D’une part, les outils actuariels gagneraient à utiliser des scores dimensionnels plutôt que des scores totaux. Par exemple, en retirant la dimension de persistance/paraphilie de la Statique-99R/2002R, il est possible de prédire efficacement la récidive violente non sexuelle et non sexuelle non violente des agresseurs sexuels, ce que l’instrument ne permettait pas précédemment. D’autre part, la connaissance des grandes dimensions de facteurs de risque est susceptible d’aider les évaluateurs à choisir et intégrer plusieurs mesures actuarielles. Cela se révèle particulièrement pertinent lorsque deux mesures du risque divergent, malgré qu’elles aient été conçues pour la même population. Finalement, nos résultats indiquent que les facteurs de risque statiques sont susceptibles de renseigner (imparfaitement) la pratique clinique quant aux besoins criminogènes des agresseurs sexuels. Bien que nous ne suggérions aucunement de substituer cette pratique à la cotation d’outils actuariels de troisième génération, elle pourrait se révéler pertinente pour les établissements n’ayant pas les ressources nécessaires pour coter de tels instruments. Au plan théorique, le modèle tridimensionnel comporte plusieurs avantages par rapport aux modèles à deux dimensions, traditionnellement constitués de la déviance sexuelle et de la délinquance générale/psychopathie (ex. : Doren, 2004). D’une part, les données empiriques supportent clairement la présence de trois dimensions du risque de récidive des agresseurs sexuels, et non deux. D’autre part, la troisième dimension permet d’intégrer une nuance importante au modèle, soit la distinction entre les intérêts sexuels déviants par leur objet de désir (ex. : pédophilie) et les intérêts sexuels déviants par leur aspect coercitif (ex. : sadisme sexuel). Cette distinction est primordiale, dans la mesure où ces intérêts sexuels ne prédisent pas les mêmes types de récidives. Finalement, notre modèle s’intègre au modèle étiologique du risque de Beech et Ward (2004), qui, lorsque complètement validé, pourra donner lieu à des efforts de prévention – une denrée rare dans le domaine.
Actuarial scales for the prediction of sexual violence have been criticised because they are purely based on atheoretical correlates. Therefore, they are unlikely to provide clinical and theoretical insight on the psychological traits and mechanisms that underlie criminal recidivism. However, according to latent variable models commonly used in psychology, patterns of behavior, thought, and emotion are caused by latent psychological constructs, such as extraversion and neuroticism. Because static and stable risk factors in actuarial scales are mostly behavioral, it should be possible to use them to infer the major psychological constructs responsible for recidivism risk. The current thesis applied latent variable models to nonredundant items from the Static-99R and Static-2002R, the two most commonly used risk tools for sexual offenders. Three dimensions were identified: 1) persistence in sexual crimes/paraphilia, 2) general criminality, and 3) youthful stranger aggression. To understand the psychological meaning of these dimensions, convergent and predictive validity analyses were conducted. Results indicated that persistence/paraphilia was related to dysregulation of sexuality towards atypical objects, without intent to harm, while general criminality was related to antisocial traits. Finally, youthful stranger aggression was related to a clear intent to harm victims. All three constructs predicted sexual recidivism with similar accuracy, but only general criminality and youthful stranger aggression predicted nonsexual recidivism. These results suggest that a tridimensional model of sexual offender risk is viable. That model has numerous practical implications. First, actuarial scales should sort items by constructs rather than rely on total scores. Total scores focus the predictive utility of risk scales to the specific outcome for which they were developed (usually sexual recidivism). When constructs are known, it is possible to improve the prediction of other outcomes by removing constructs unrelated to each of these new outcomes (e.g., removing sexual criminality items to improve the prediction of nonsexual recidivism). Second, construct-level approaches facilitate the integration of potentially conflicting risk scales. By understanding the constructs assessed by each scale, an evaluator can deduce which measures should be combined, and which should not. Finally, static risk constructs significantly correlate with psychological features that are found in dynamic risk scales. Consequently, scales composed entirely of static risk factors could – albeit imperfectly – inform the treatment needs of sexual offenders. These results could assist settings lacking the resources to implement dynamic risk tools. The tridimensional model also has theoretical implications. First, our model showed better statistical fit than classical two factor models based on sexual deviance and psychopathy (e.g., Doren, 2004), suggesting that there are more than two substantive dimensions related to sexual offender recidivism risk. Second, the presence of a third factor enabled an important distinction between noncoercive (e.g., fixated pedophilia) and coercive (e.g., sexual sadism) deviant sexual interests. Such a distinction is particularly relevant in the field of risk assessment, because they do not predict the same types of recidivism. Finally, our model can be integrated in Beech and Ward’s (2004) etiological model of risk, which, once fully validated, could enable primary and secondary prevention efforts.