Dissertations / Theses on the topic 'Periodic prediction'
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1
Chen, Jin-Jae. "Prediction of periodic forced response of frictionally constrained turbine blades /." The Ohio State University, 1999. http://rave.ohiolink.edu/etdc/view?acc_num=osu1488187763847997.
2
Sadat, Hosseini Seyed Hamid Stern Frederick Carrica Pablo M. "CFD prediction of ship capsize parametric rolling, broaching, surf-riding, and periodic motions /." [Iowa City, Iowa] : University of Iowa, 2009. http://ir.uiowa.edu/etd/427.
3
Date, James Charles. "Performance prediction of high lift rudders operating under steady and periodic flow conditions." Thesis, University of Southampton, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.390722.
4
Sadat, Hosseini Seyed Hamid. "CFD prediction of ship capsize: parametric rolling, broaching, surf-riding, and periodic motions." Diss., University of Iowa, 2009. https://ir.uiowa.edu/etd/427.
Abstract:
Stability against capsizing is one of the most fundamental requirements to design a ship. In this research, for the first time, CFD is performed to predict main modes of capsizing. CFD first is conducted to predict parametric rolling for a naval ship. Then CFD study of parametric rolling is extended for prediction of broaching both by using CFD as input to NDA model of broaching in replacement of EFD inputs or by using CFD for complete simulation of broaching. The CFD resistance, static heel and drift in calm water and static heel in following wave simulations are conducted to estimate inputs for NDA and 6DOF simulation in following waves are conducted for complete modeling of broaching.
CFD parametric rolling simulations show remarkably close agreement with EFD. The CFD stabilized roll angle is very close to those of EFD but CFD predicts larger instability zones. The CFD and EFD results are analyzed with consideration ship theory and compared with NDA. NDA predictions are in qualitative agreement with CFD and EFD.
CFD and EFD full Fr curve resistance, static heel and drift in calm water, and static heel in following waves results show fairly close agreement. CFD shows reasonable agreement for static heel and drift linear maneuvering derivatives, whereas large errors are indicated for nonlinear derivatives. The CFD and EFD results are analyzed with consideration ship theory and compared with NDA models. The surge force in following wave is also estimated from Potential Theory and compared with CFD and EFD. It is shown that CFD reproduces the decrease of the surge force near the Fr of 0.2 whereas Potential Theory fails.
The CFD broaching simulations are performed for series of heading and Fr and results are compared with the predictions of NDA based on CFD, EFD, and Potential Theory inputs. CFD free model simulations show promising results predicting the instability boundary accurately. CFD calculation of wave and rudders yaw moment explains the processes of surf-riding, broaching, and periodic motion. The NDA simulation using CFD and Potential Flow inputs suggests that CFD/ Potential Flow can be considered as replacement for EFD inputs.
5
Perreira, Das Chagas Thiago. "Stabilization of periodic orbits in discrete and continuous-time systems." Phd thesis, Université Paris Sud - Paris XI, 2013. http://tel.archives-ouvertes.fr/tel-00852424.
Abstract:
The main problem evaluated in this manuscript is the stabilization of periodic orbits of non-linear dynamical systems by use of feedback control. The goal of the control methods proposed in this work is to achieve a stable periodic oscillation. These control methods are applied to systems that present unstable periodic orbits in the state space, and the latter are the orbits to be stabilized.The methods proposed here are such that the resulting stable oscillation is obtained with low control effort, and the control signal is designed to converge to zero when the trajectory tends to the stabilized orbit. Local stability of the periodic orbits is analyzed by studying the stability of some linear time-periodic systems, using the Floquet stability theory. These linear systems are obtained by linearizing the trajectories in the vicinity of the periodic orbits.The control methods used for stabilization of periodic orbits here are the proportional feedback control, the delayed feedback control and the prediction-based feedback control. These methods are applied to discrete and continuous-time systems with the necessary modifications. The main contributions of the thesis are related to these methods, proposing an alternative control gain design, a new control law and related results.
6
Lindsey, Justin. "Fatigue Behavior in the Presence of Periodic Overloads Including the Effects of Mean Stress and Inclusions." University of Toledo / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1319554971.
7
Borda, Jorge Victor Quiñones. "Log periodic analysis of critical crashes in the portuguese stock market." Master's thesis, Instituto Superior de Economia e Gestão, 2015. http://hdl.handle.net/10400.5/11082.
Abstract:
Mestrado em Ciências EmpresariaisO estudo de fenómenos críticos que se originaram nas ciências naturais e encontraram muitos campos de aplicação foi estendido nos últimos anos aos campos da economia de finanças, fornecendo aos investigadores novas abordagens para problemas conhecidos, nomeadamente aos que estão relacionados com a gestão de risco, a previsão, o estudo de bolhas financeiras e crashes, e muitos outros tipos de problemas que envolvem sistemas com criticalidade auto-organizada. A teoria de singularidades de tempo oscilatório auto-similares é apresentada, uma metodologia prática é exposta, juntamente com alguns resultados de análises semelhantes de diferentes mercados em todo o mundo, como uma maneira de obter de alguns exemplos da forma como a função "linear" log-periódica de potências funciona. Apresento alguns contextos onde o tempo de crise é apresentado aos mercados internacionais - como uma maneira de demonstração de antecedentes -, assim como apresento também três aplicações práticas do mercado de acções português (1997, 2008 e 2015). A sensibilidade dos resultados e do significado das oscilações log-periódicas são avaliadas. Concluo com algumas recomendações e futuras propostas de investigação.
The study of critical phenomena that originated in the natural sciences and found many fields of applications has been extended in the last years to the financial economics? field, giving researchers new approaches to known problems, namely those related to risk management, forecasting, the study of bubbles and crashes, and many kind of problems involving complex systems with self-organized criticality. The theory of self-similar oscillatory time singularities is presented. A practical methodology is exposed along with some results from similar analysis from different markets around the world, as a way to get some examples of the way the ´Linear´ Log-Periodic Power Law formula works. Some context presenting the international markets at the time of crisis is given as a way of having some background, and three practical applications for the Portuguese stock market are made (1997, 2008 and 2015). The sensitivity of the results and the significance from the log-periodic oscillations is assessed. It concludes with some recommendations and future proposed research.
8
Devarasetty, Ravi Kiran. "Heuristic Algorithms for Adaptive Resource Management of Periodic Tasks in Soft Real-Time Distributed Systems." Thesis, Virginia Tech, 2001. http://hdl.handle.net/10919/31219.
Abstract:
Dynamic real-time distributed systems are characterized by significant run-time uncertainties at the mission and system levels. Typically, processing and communication latencies in such systems do not have known upper bounds and event and task arrivals and failure occurrences are non-deterministically distributed. This thesis proposes adaptive resource management heuristic techniques for periodic tasks in dynamic real-time distributed systems with the (soft real-time) objective of minimizing missed deadline ratios. The proposed resource management techniques continuously monitor the application tasks at run-time for adherence to the desired real-time requirements, detects timing failures or trends for impending failures (due to workload fluctuations), and dynamically allocate resources by replicating subtasks of application tasks for load sharing. We present "predictive" resource allocation algorithms that determine the number of subtask replicas that are required for adapting the application to a given
workload situation using statistical regression theory. The algorithms use regression equations that forecast subtask timeliness as a function of external load parameters such as number of sensor reports and internal resource load parameters such as CPU utilization. The regression equations are determined off-line and on-line from application profiles that are collected off-line and on-line, respectively. To evaluate the performance of the predictive algorithms, we consider algorithms that determine the number of subtask replicas using empirically determined functions. The empirical functions compute the number of replicas as a function of the rate of change in the application workload during a "window" of past task periods. We implemented the resource management algorithms as part of a middleware infrastructure and measured the performance of the algorithms using a real-time benchmark. The experimental results indicate that the predictive, regression theory-based algorithms generally produce lower missed
deadline ratios than the empirical strategies under the workload conditions that were studied.Master of Science
9
Kamisetty, Jananni Narasimha Shiva Sai Sri Harsha Vardhan. "Forecasting Trajectory Data : A study by Experimentation." Thesis, Blekinge Tekniska Högskola, Institutionen för kommunikationssystem, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-13976.
Abstract:
Context. The advances in location-acquisition and mobile computing techniques have generated massive spatial trajectory data. Such spatial trajectory data accumulated by telecommunication operators is huge, analyzing the data with a right tool or method can uncover patterns and connections which can be used for improving telecom services. Forecasting trajectory data or predicting next location of users is one of such analysis. It can be used for producing synthetic data and also to determine the network capacity needed for a cell tower in future. Objectives. The objectives of this thesis is, Firstly, to have a new application for CWT (Collapsed Weighted Tensor) method. Secondly, to modify the CWT method to predict the location of a user. Thirdly, to provide a suitable method for the given Telenor dataset to predict the user’s location over a period of time. Methods. The thesis work has been carried out by implementing the modified CWT method. The predicted location obtained by modified CWT cannot be determined to which time stamp it belongs as the given Telenor dataset contains missing time stamps. So, the modified CWT method is implemented in two different methods. Replacing missing values with first value in dataset. Replacing missing values with second value in dataset. These two methods are implemented and determined which method can predict the location of users with minimal error. Results. The results are carried by assuming that the given Telenor dataset for one week will be same as that for the next week. Users are selected in a random sample and above mentioned methods are performed. Furthermore, RMSD values and computational time are calculated for each method and selected users. Conclusion. Based on the analysis of the results, Firstly, it can be concluded that CWT method have been modified and used for predicting the user’s location for next time stamp. Secondly, the method can be extended to predict over a period of time. Finally, modified CWT method predicts location of the user with minimal error when missing values are replaced by first value in the dataset.
10
Levin, Ori. "Numerical studies of transtion in wall-bounded flows." Doctoral thesis, KTH, Mechanics, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-546.
Abstract:
Disturbances introduced in wall-bounded flows can grow and lead to transition from laminar to turbulent flow. In order to reduce losses or enhance mixing in energy systems, a fundamental understanding of the flow stability and transition mechanism is important. In the present thesis, the stability, transition mechanism and early turbulent evolution of wall-bounded flows are studied. The stability is investigated by means of linear stability equations and the transition mechanism and turbulence are studied using direct numerical simulations. Three base flows are considered, the Falkner-Skan boundary layer, boundary layers subjected to wall suction and the Blasius wall jet. The stability with respect to the exponential growth of waves and the algebraic growth of optimal streaks is studied for the Falkner-Skan boundary layer. For the algebraic growth, the optimal initial location, where the optimal disturbance is introduced in the boundary layer, is found to move downstream with decreased pressure gradient. A unified transition prediction method incorporating the influences of pressure gradient and free-stream turbulence is suggested. The algebraic growth of streaks in boundary layers subjected to wall suction is calculated. It is found that the spatial analysis gives larger optimal growth than temporal theory. Furthermore, it is found that the optimal growth is larger if the suction begins a distance downstream of the leading edge. Thresholds for transition of periodic and localized disturbances as well as the spreading of turbulent spots in the asymptotic suction boundary layer are investigated for Reynolds number Re=500, 800 and 1200 based on the displacement thickness and the free-stream velocity. It is found that the threshold amplitude scales like Re^-1.05 for transition initiated by streamwise vortices and random noise, like Re^-1.3 for oblique transition and like Re^-1.5 for the localized disturbance. The turbulent spot is found to take a bullet-shaped form that becomes more distinct and increases its spreading rate for higher Reynolds number. The Blasius wall jet is matched to the measured flow in an experimental wall-jet facility. Both the linear and nonlinear regime of introduced waves and streaks are investigated and compared to measurements. It is demonstrated that the streaks play an important role in the breakdown process where they suppress pairing and enhance breakdown to turbulence. Furthermore, statistics from the early turbulent regime are analyzed and reveal a reasonable self-similar behavior, which is most pronounced with inner scaling in the near-wall region.
11
Bouzayane, Sarra. "Méthode de classification multicritère, incrémentale et périodique appliquée à la recommandation pour l'aide au transfert des savoirs dans les MOOCs." Electronic Thesis or Diss., Amiens, 2017. http://www.theses.fr/2017AMIE0029.
Abstract:
La thèse aborde la problématique de transfert de connaissances dans les environnements médiatisés à l'ère de la massification de données. Nous proposons une méthode d'aide à la décision multicritère MAI2P (Multicriteria Approach for the Incremental Periodic Prediction) pour la prédiction périodique et incrémentale de la classe de décision à laquelle une action est susceptible d'appartenir. La méthode MAI2P repose sur trois phases. La première phase est composée de trois étapes : la construction d'une famille de critères pour la caractérisation des actions ; la construction d'un ensemble des “Actions de référence” représentatif pour chacune des classes de décision ; et la construction d'une table de décision. La deuxième phase s'appuie sur l'algorithme DRSA-Incremental que nous proposons pour l'inférence et la mise à jour de l'ensemble de règles de décision suite à l'incrémentation séquentielle de l'ensemble des “actions de référence”. La troisième phase permet de classer les “Actions potentielles” dans l'une des classes de décision en utilisant l'ensemble de règles de décision inféré. La méthode MAI2P est validée sur un contexte des MOOCs (Massive Open Online Courses) qui sont des formations en ligne caractérisées par une masse importante de données échangées entre un nombre massif d’apprenants. Elle a permis la prédiction hebdomadaire des trois classes de décision : Cl1 des “Apprenants en risque” d'abandonner le MOOC; Cl2 des “Apprenants en difficulté” mais n'ayant pas l'intention d'abandon ; et Cl3 des “Apprenants leaders” susceptibles de soutenir les deux autres classes d'apprenants en leur transmettant l'information dont ils ont besoin. La prédiction est basée sur les données de toutes les semaines précédentes du MOOC afin de prédire le profil de l'apprenant pour la semaine suivante. Un système de recommandation KTI-MOOC (Recommender system for the Knowledge Transfer Improvement within a MOOC) est développé pour recommander à chaque “Apprenant en risque” ou “Apprenant en difficulté” une liste personnalisée des “Apprenants leaders”. Le système KTI-MOOC est basé sur la technique de filtrage démographique et a l'objectif de favoriser l'appropriation individuelle, des informations échangées, auprès de chaque apprenantThe thesis deals with the problem of knowledge transfer in mediated environments in the era of massive data. We propose a Multicriteria Approach for the Incremental Periodic Prediction (MAI2P) of the decision class to which an action is likely to belong. The MAI2P method is based on three phases. The first consists of three steps : the construction of a family of criteria for the characterization of actions ; the construction of a representative set of “Reference actions” for each of the decision classes ; and the construction of a decision table. The second phase is based on the DRSA-Incremental algorithm that we propose for the inference and the updating of the set of decision rules following the sequential increment of the “Reference actions” set. The third phase is meant to classify the “Potential Actions” in one of the predefined decision classes using the set of inferred decision rules. The MAI2P method is validated especially in the context of the Massive Open Online Courses (MOOCs), which are e-courses characterized by a huge amount of data exchanged between a massive number of learners. It allows the weekly prediction of the three decision classes : Cl1 of the “At risk learners”, those who intend to give up the MOOC; Cl2 of the “Struggling learners”, those who have pedagogical difficulties but have no plan to abandon it ; and Cl3 of the “Leader learners”, those who can support the other two classes of learners by providing them with all the information they need. The prediction is based on data from all the previous weeks of the MOOC in order to predict the learner profile for the following week. A recommender system KTI-MOOC (Recommender system for Knowledge Transfer Improvement within a MOOC) is developed to recommend to each “At risk learner” or “Struggling learner” a personalized list of “Leader learners”. This system is based on the demographic filtering technique and aims to promote the individual appropriation, of the exchanged information, for each learner
12
Hodozsán, Tamás. "Timed Recidivism. In search for critical periods to supplement interventions." Thesis, Malmö universitet, Fakulteten för hälsa och samhälle (HS), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:mau:diva-25866.
Abstract:
Assessing risk had always been the key focus when it comes to recidivism. Using risk assessment instruments, it is possible to predict the outcome of recidivism dichotomously. These measures, however, can only predict between 70-80 percent of validity, and they specify only levels of risk (low-medium-high), but not time. Therefore, the aim of this study is to define time of recidivism to supplement risk assessment with a possible new actuarial approach and fill out gaps in the existing literature. To do so a systematic literature review was conducted with a controlled search on exact time points. All the fourteen studies resulted in the final model were: published in the past 20 years, had some connection to time and were quantitative. The results highlighted the importance of the first year, especially the first half of the year as the most critical period regarding recidivism. Three different time periods were identified: (1) the end of the first month; (2) between the second and the third; (3) at the end of the 6th. Consequently, it might be beneficial to target these critical periods with more intense supervision/intervention in order to decrease the likelihood of recidivism.
13
Wells, Daniel Patrick. "Predicting the Longevity of DVDR Media by Periodic Analysis of Parity, Jitter, and ECC Performance Parameters." BYU ScholarsArchive, 2008. https://scholarsarchive.byu.edu/etd/1530.
Abstract:
For the last ten years, DVD-R media have played an important role in the storage of large amounts of digital data throughout the world. During this time it was assumed that the DVD-R was as long-lasting and stable as its predecessor, the CD-R. Several reports have surfaced over the last few years questioning the DVD-R's ability to maintain many of its claims regarding archival quality life spans. These reports have shown a wide range of longevity between the different brands. While some DVD-Rs may last a while, others may result in an early and unexpected failure. Compounding this problem is the lack of information available for consumers to know the quality of the media they own. While the industry works on devising a standard for labeling the quality of future media, it is currently up to the consumer to pay close attention to their own DVD-R archives and work diligently to prevent data loss. This research shows that through accelerated aging and the use of logistic regression analysis on data collected through periodic monitoring of disc read-back errors it is possible to accurately predict unrecoverable failures in the test discs. This study analyzed various measurements of PIE errors, PIE8 Sum errors, POF errors and jitter data from three areas of the disc: the whole disc, the region of the disc where it first failed as well as the last half of the disc. From this data five unique predictive equations were produced, each with the ability to predict disc failure. In conclusion, the relative value of these equations for end-of-life predictions is discussed.
14
Budanur, Nazmi Burak. "Exact coherent structures in spatiotemporal chaos: From qualitative description to quantitative predictions." Diss., Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/54445.
Abstract:
The term spatiotemporal chaos refers to physical phenomena that exhibit irregular oscillations in both space and time. Examples of such phenomena range from cardiac dynamics to fluid turbulence, where the motion is described by nonlinear partial differential equations. It is well known from the studies of low dimensional chaotic systems that the state space, the space of solutions to the governing dynamical equations, is shaped by the invariant sets such as equilibria, periodic orbits, and invariant tori. State space of partial differential equations is infinite dimensional, nevertheless, recent computational advancements allow us to find their invariant solutions (exact coherent structures) numerically. In this thesis, we try to elucidate the chaotic dynamics of nonlinear partial differential equations by studying their exact coherent structures and invariant manifolds. Specifically, we investigate the Kuramoto-Sivashinsky equation, which describes the velocity of a flame front, and the Navier-Stokes equation for an incompressible fluid in a circular pipe. We argue with examples that this approach can lead to a theory of turbulence with predictive power.
15
Wells, Daniel Patrick. "Predicting the longevity of DVD-R media by periodic analysis of Parity, jitter, and ECC performance parameters /." Diss., CLICK HERE for online access, 2008. http://contentdm.lib.byu.edu/ETD/image/etd2526.pdf.
16
Lan, Yang. "Computational Approaches for Time Series Analysis and Prediction. Data-Driven Methods for Pseudo-Periodical Sequences." Thesis, University of Bradford, 2009. http://hdl.handle.net/10454/4317.
Abstract:
Time series data mining is one branch of data mining. Time series analysis and prediction have always played an important role in human activities and natural sciences. A Pseudo-Periodical time series has a complex structure, with fluctuations and frequencies of the times series changing over time. Currently, Pseudo-Periodicity of time series brings new properties and challenges to time series analysis and prediction. This thesis proposes two original computational approaches for time series analysis and prediction: Moving Average of nth-order Difference (MANoD) and Series Features Extraction (SFE). Based on data-driven methods, the two original approaches open new insights in time series analysis and prediction contributing with new feature detection techniques. The proposed algorithms can reveal hidden patterns based on the characteristics of time series, and they can be applied for predicting forthcoming events. This thesis also presents the evaluation results of proposed algorithms on various pseudo-periodical time series, and compares the predicting results with classical time series prediction methods. The results of the original approaches applied to real world and synthetic time series are very good and show that the contributions open promising research directions.
17
Daughtrey, Cannon Stewart. "Pima County's Open Space Ranch Preserves: Predictive Modeling of Site Locations for Three Time Periods at Rancho Seco." Thesis, The University of Arizona, 2014. http://hdl.handle.net/10150/318809.
Abstract:
The initiatives of open space conservation, as outlined in the Sonoran Desert Conservation Plan, have been implemented through the purchase of nearly 65 thousand acres by Pima County. This land abuts sections of grazing leases held by state and federal agencies, forming largely unfragmented landscapes surrounding the city's urban core. Much of the outlying acreage is rural historic working ranches, now managed as open space conservation preserves. Ranches are landscapes of low-intensity impact, where the archaeological record of centuries of human land use is well preserved. Much of the land, however, remains relatively unstudied. To refine spatial predictions of archaeologically sensitive areas in southern Pima County, I use multivariate logistic regression to develop predictive models of probable archaeological site locations for three time periods at Rancho Seco as a case study. Results suggest portions Rancho Seco might contain additional Preceramic and Historic cultural resources but additional data collection is needed.
18
Sherman, Brook W. "The Examination and Evaluation of Dynamic Ship Quiescence Prediction and Detection Methods for Application in the Ship-Helicopter Dynamic Interface." Thesis, Virginia Tech, 2007. http://hdl.handle.net/10919/32436.
Abstract:
Motion sensitive operations at sea are conducted in an unpredictable environment. While occasionally these operations can be planned around suitable weather forecast or delayed until smoother motions are apparent, naval ships conducting flight operations may have little liberty in their mission planning and execution. Tools exist to translate the oceanâ s harsh conditions into discretely defined low motion operational periods. Particularly of interest, the identification of discrete lull periods or quiescence for shipboard helicopter operations can be better defined using a landing period indicator than with the current method of utilizing static deck angle measurements. While few of these systems exist, assessing their operational benefits is difficult due to a lack of well-defined performance metrics.
This thesis defines and examines the use of two methodical approaches to evaluating Landing Period Indicators (LPIs) and their subject ship-helicopter dynamic interface system. First a methodology utilizing the comparison of a basic transparent algorithm is detailed and a case study employing this methodology is examined. Second, a system dynamics approach is taken to pilot workload analysis, utilizing a dynamic systems model characterizing a subset of the Dynamic Interface. This approach illustrates the realistic gains in understanding and development that can be accomplished by utilizing system dynamics in the analysis of the Dynamic Interface and LPI insertion.
Master of Science
19
Wlodarczyk, Radoslaw Stanislaw. "Surface structure predictions and development of global exploration tools." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät, 2015. http://dx.doi.org/10.18452/17207.
Abstract:
Diese Arbeit ist ein Beitrag zur theoretischen Chemie sowie zur Oberflächenchemie. Durch Kombination von computergestützten und experimentellen Untersuchungen wird die atomare Struktur von dünnen SiO2-Filmen auf Ru(0001)-Unterlagen, von eisendotierten SiO2-Filmen auf diesen Unterlagen und von H2O-Filmen auf MgO(001)-Oberflächen bestimmt. Die atomaren Strukturmodelle wurden entweder mit dem neu entworfenen und im Paket DoDo implementierten genetischen Algorithmus oder mittels auf Sachkenntnis gestützter Vermutungen erhalten. Die simulierten Eigenschaften der so erhaltenen Strukturen stimmen sehr gut mit den experimentellen Daten (Raster-Tunnel-Mikroskopie, Infrarot-Spektroskopie) überein. Die erfolgreiche Strukturbestimmung mithilfe des DoDo-Programms zeigt, dass genetische Algorithmen zur systematischen und extensiven Erkundung der Energielandschaften 2D-periodischer Systeme geeignet sind.This work is a contribution in the field of theoretical chemistry and surface science. The joint computational and experimental studies investigated the atomic structure of ultrathin silica and iron-doped silica films formed on the Ru(0001) surface and water films formed on the MgO(001) surface. The atomic structure models were obtained using either the educated guess approach or the genetic algorithm that was designed and implemented within the DoDo package. The properties simulated for the resulting models are in a very good agreement with the experimental data (scanning tunnelling microscopy, infrared spectroscopy). The successful structure determination using the DoDo program shows that the genetic algorithm technique is capable of systematic and extensive exploration of the energy landscapes for 2D-periodic systems.
20
Hanson-Cook, Blair M. A. "Predicting Long-term Flourishing Outcomes Among Sensitive and Non-sensitive Children." University of Cincinnati / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=ucin162765956265785.
21
Erdurmaz, Muammer Sercan. "Neural Network Prediction Of Tsunami Parameters In The Aegean And Marmara Seas." Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/12605134/index.pdf.
Abstract:
Tsunamis are characterized as shallow water waves, with long periods and wavelengths. They occur by a sudden water volume displacement. Earthquake is one of the main reasons of a tsunami development. Historical data for an observation period of 3500 years starting from 1500 B.C. indicates that approximately 100 tsunamis occurred in the seas neighboring Turkey.
Historical earthquake and tsunami data were collected and used to develop two artificial neural network models to forecast tsunami characteristics for future occurrences and to estimate the tsunami return period. Artificial Neural Network (ANN) is a system simulating the human brain learning and thinking behavior by experiencing measured or observed data.
A set of artificial neural network is used to estimate the future earthquakes that may create a tsunami and their magnitudes. A second set is designed for the estimation of tsunami inundation with relation with the tsunami intensity, the earthquake depth and the earthquake magnitude that are predicted by the first set of neural networks.
In the case study, Marmara and Aegean regions are taken into consideration for the estimation process. Return periods including the last occurred earthquake in the Turkish seas, which was the izmit (Kocaeli) Earthquake in 1999, were utilized together with the average earthquake depths calculated for Marmara and Aegean regions for the prediction of the earthquake magnitude that may create a tsunami in the stated regions for various return periods of 1-100 years starting from the year of 2004. The obtained earthquake magnitudes were used together with tsunami intensities and earthquake depth to forecast tsunami wave height at the coast.
It is concluded that, Neural Networks predictions were a satisfactory first step to implement earthquake parameters such as depth and magnitude, for the average tsunami height on the shore calculations.
22
Delgadillo, Penadillo Alan Cristopher. "Valor predictívo del diagnóstico ultrasonográfico en la detección de anomalías congénitas más frecuentes en gestantes de 11 a 14 semanas atendidas en la unidad básica de atención primaria de salud - Barranco (UBAP-ESSALUD) durante el periodo enero – marzo del año 2013." Bachelor's thesis, Universidad Nacional Mayor de San Marcos, 2015. https://hdl.handle.net/20.500.12672/4319.
Abstract:
INTRODUCCIÓN: Las anomalías congénitas constituyen un capítulo cada vez más importante tanto para la obstetricia como para la neonatología, la genética y la biología; debido a su relativa alta frecuencia, a la posibilidad de su diagnóstico prenatal y a los enormes progresos que se están realizando para comprender mejor su epidemiología, fisiopatología y sobre todo a la posibilidad de diagnóstico cada vez más precoz y en ocasiones, tratarlas.
OBJETIVOS: Determinar el valor predictivo del diagnóstico ultrasonográfico en la detección de anomalias congénitas más frecuentes en gestantes de 11 a 14 semanas atendidas en la Unidad Básica de Atención Primaria de Barranco (UBAP). Lima. Enero- Marzo, 2013.
DISEÑO Y METODOS: El presente estudio es de tipo descriptivo, de corte transversal, retrospectivo y cuantitativo. Se seleccionó 113 historias clínicas de pacientes gestantes, se recolectó la información en un formato de recolección de datos, ordenando las variables según Edad, Paridad y resultados de exámenes ecográficos, y en algunos casos el resultado de la amniocentesis (Prueba de Oro) para la comparación posterior con los resultados ecográficos. Los datos fueron pasados al software SPSS v.21, se ordenaron y etiquetaron las variables para su posterior análisis.
RESULTADOS: La edad promedio de pacientes es 31,5 años; el 50% tiene 31 años o más; la varianza es de 50,7; las distancias promedio de cada edad con respecto a la media es de 7,1; el marcador ecográfico más frecuente encontrado fue: translucencia nucal aumentada 2,7% y ausencia de hueso nasal 0,9%.
CONCLUSIONES: La evaluación de anomalías congénitas por ultrasonografía debe considerarse un método fiable como diagnostico precoz ya que presenta un valor predictivo mayor al 90%. El valor predictivo positivo y el valor predictivo negativo de la ultrasonografía en contraste a los casos confirmados mediante la amniocentesis (prueba de oro) es 96% y 100% respectivamente; La Sensibilidad y especificidad de la ultrasonografía es del 80% y 100% respectivamente.INTRODUCTION: Congenital anomalies constitute an increasingly important for both obstetrics and neonatology for the chapter, genetics and biology; because of its relatively high frequency, the possibility of prenatal diagnosis and the tremendous progress being made to better understand the epidemiology, pathophysiology and especially the possibility of increasing early diagnosis and sometimes treat them. OBJECTIVES: To determine the predictive value of ultrasound diagnosis in detecting most common congenital anomalies in pregnant women between 11 and 14 weeks served in the Basic Unit of Primary Care Barranco (UBAP). Lima. January-March, 2013. DESIGN AND METHODS: This study is descriptive, cross-sectional, retrospective and quantitative nature. 113 medical records of pregnant patients were selected, information was collected in a data collection form, ordering the variables as age, parity and results of ultrasound examinations, and in some cases the result of amniocentesis (Test de Oro) for the subsequent comparison with ultrasound results. Data were passed to SPSS v.21 software; they were sorted and labeled variables for further analysis. RESULTS: The mean age of patients was 31.5 years; 50% have 31 years or more; the variance is 50.7; the average distances of age with respect to each average is 7.1; the most frequent ultrasound marker was found: 2.7% increased nuchal translucency and nasal bone absence of 0.9%. CONCLUSIONS: The evaluation of congenital anomalies by ultrasound should be considered a reliable method as early diagnosis because it has a higher predictive value 90%. The positive predictive value and negative predictive value of ultrasonography in contrast to cases confirmed by amniocentesis (gold standard) is 96% and 100% respectively; the sensitivity and specificity of ultrasonography is 80% and 100% respectively. KEYWORDS: conventional ultrasound, sensitivity, specificity, positive predictive value, negative predictive value, congenital anomaly.
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CHANDRASEKARAN, LATHA. "PREDICTING DISEASE INCIDENCE DUE TO CONTAMINATED INTRUSION IN A WATER DISTRIBUTION SYSTEM." University of Cincinnati / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1155506232.
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Elmqvist-Möller, Christel. "1-D simulation of turbocharged SI engines : focusing on a new gas exchange system and knock prediction." Licentiate thesis, KTH, Machine Design (Div.), 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4218.
Abstract:
This licentiate thesis concerns one dimensional flow simulation of turbocharged spark ignited engines. The objective has been to contribute to the improvement of turbocharged SI engines’ performance as well as 1 D simulation capabilities.
Turbocharged engines suffer from poor gas exchange due to the high exhaust pressure created by the turbine. This results in power loss as well as high levels of residual gas, which makes the engine more prone to knock.
This thesis presents an alternative gas exchange concept, with the aim of removing the high exhaust pressure during the critical periods. This is done by splitting the two exhaust ports into two separate exhaust manifolds.
The alternative gas exchange study was performed by measurements as well as 1-D simulations. The link between measurements and simulations is very strong, and will be discussed in this thesis.
As mentioned, turbocharged engines are prone to knock. Hence, finding a method to model knock in 1-D engine simulations would improve the simulation capabilities. In this thesis a 0-D knock model, coupled to the 1-D engine model, is presented
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Rosso, T. "METODI STATISTICI PER L'ANALISI E LA PREVISIONE DELLA MORTALITA' PER TUMORE." Doctoral thesis, Università degli Studi di Milano, 2015. http://hdl.handle.net/2434/344554.
Abstract:
The introduction of time series modeling techniques made analyzing the different factors underlying the changes in mortality and incidence rates over time possible, both for analytic and predictive purposes. Age-period-cohort analyses contribute to the etiologic purpose of descriptive epidemiology making inference from the group to the individual possible. These refer to a family of statistical techniques that study the temporal trends of outcomes, such as mortality an incidence, in terms of three temporal variables: subject age, calendar period and the subject's birth cohort. Useful as it is, the age-period-cohort model is marred by a structural problem of identifiability: the variables of age, period and cohort have an exact linear dependence, i.e. "age = period - cohort".
Predicting a future event is a complex and insidious process, however, it is a useful endeavor in most human activities. The information gained on probable future trends, even if unreliable or imprecise is highly valuable. Predicted future cancer incidence and mortality rates are essential tools for both epidemiology and health planning.
Numerous methods to carry out age-period-cohort analysis are described in the literature, three of these are illustrated in detail and compared by applying them to real data (WHO mortality database): a method based on penalized likelihood, one using generalized additive models (GAM) and one based on partial least squares (PLS) techniques.
Predictive analysis techniques are also presented and compared, using observed mortality data. Short term age-period prediction methods based on joinpoint analysis and Bayesian modelling, and a long term technique, which uses a Bayesian age-period-cohort model, are reviewed. In details, predictions through age-period method based on joinpoint analysis are carried out applying linear, Poisson and log-linear regression models.
In the age-period-cohort analysis comparison, the penalized likelihood and GAM methods produce similar results, while effect estimates from the PLS model are noticeably different. These differences can be explained by looking at how the three models solve the issue of perfect collinearity between age, period and cohort parameters. On the one hand, the penalized likelihood and GAM methods use different techniques to distribute the linear drift between the period and cohort effects. The PLS method, on the other hand, solves the identifiability problem by tackling the generalized inverse, minimizing the estimated parameter variance and covariance matrix. Without a formal simulation analysis, comments are limited to stating that the two models based on linear drift distribution are more suitable for epidemiological comparisons, where the effects of age are well defined (as in the case of cancer mortality) and the major problems reside in untangling the period and cohort effects. The PLS model, on the other hand, may hypothetically prove to be a useful method to predict future trends. Age-period-cohort analysis is thus an extremely useful tool in the study of mortality data, particularly for cohort effect analysis, but it should be used with due caution since it is relatively easy to draw erroneous conclusions.
The predictive method comparison shows that estimates from the different models are similar, especially for the Poisson and log-linear models. However, the linear model has a tendency to underestimate, while the other considered models seem to overestimate, particularly as the forecasting time period grew larger. Overall, the Bayesian age-period model seems to be less suitable for short and medium term mortality predictions, while the other models do not show large performance differences. From these limited tests the linear model and the Bayesian age-period-cohort model seem to provide better estimates when mortality values are low, whereas in the case of greater numbers Poisson and log-linear models seem like better choices. Finally, the analyzed data's unknown underlying distribution shape determines which model predicts more successfully. However, all the studied models are appropriate for predicting data over short periods (up to 5 years). While none of them performs well over the medium term. Prediction of future trends will always be a complex and insidious exercise, albeit an extremely useful one, furthermore the obtained estimates should be taken with caution and only regarded as a general indication of potential interest for epidemiology and health planning.
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Meza, Córdova Ivan Arturo. "Trombocitopenia como predictor de sepsis tardía en neonatos atendidos en el Hospital III de Emergencias Grau en el periodo 2012-2013." Bachelor's thesis, Universidad Nacional Mayor de San Marcos, 2014. https://hdl.handle.net/20.500.12672/9621.
Abstract:
Publicación a texto completo no autorizada por el autorDemuestra que la trombocitopenia tiene valor predictor de sepsis tardía en neonatos para una identificación precoz de este diagnóstico. El presente estudio es observacional, retrospectivo, transversal de tipo prueba diagnóstica. Se realizó en el Hospital III Emergencias Grau (H. docente). El material utilizado son las historias clínicas de neonatos con diagnóstico de sepsis tardía corroborado por dos hemocultivos positivos y un grupo control de recién nacidos sanos. Se recogió la muestra indicada. Se usó R statistic versión 2.13.2, y el paquete EPIDAT. Se aplicó un modelo de regresión logística por pasos para evaluar la capacidad predictiva de la trombocitopenia. Se evaluó la utilidad diagnóstica mediante la sensibilidad, especificidad, valor predictivo positivo y valor predictivo negativo. Finalmente mediante la curva ROC se valoró la exactitud diagnostica. Resultados: De 202 recién nacidos, 37 de ellos tuvieron sepsis tardía confirmada por hemocultivo frente a 165 controles. El germen más frecuente aislado fue Staphylococcus. Se confirmó que la trombocitopenia es un predictor estadísticamente significativo de sepsis (valor p= 0,007) e independiente de los otros factores incluidos en el modelo. La trombocitopenia muestra una sensibilidad del 18,9%, especificidad de 95,8%, valor predictivo positivo de 50% y un valor predictivo negativo de 84%. Tiene una exactitud diagnóstica regular para la detección de sepsis neonatal tardía según el área bajo la curva (prueba ROC). En concluisón se demuestra que la trombocitopenia puede ser usada como predictor de sepsis tardía con una especificidad superior al 95%, sin embargo no es suficiente para ser el único predictor de sepsis.
Tesis
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Navarro, Romero Tito. "Correlación con la histología y valor predictivo de la resonancia magnética para el diagnóstico de cáncer de mama durante el periodo 2008-2013." Bachelor's thesis, Universidad Nacional Mayor de San Marcos, 2014. https://hdl.handle.net/20.500.12672/13093.
Abstract:
Introducción: El cáncer de mama constituye la neoplasia más frecuente en el sexo femenino, siendo la primera causa de muerte por cáncer en mujeres. La resonancia magnética es una herramienta útil para detección y caracterización del cáncer de mama. En casos adecuadamente indicados ayuda a valorar extensión, evaluación y respuesta al tratamiento y guía para biopsia. Debido a esto, y por no contar con estudios propios de resonancia magnética de mama de nuestra realidad, nació el interés por realizar esta investigación y poder contrastar con otras realidades.
Objetivos: Determinar la correlación con la histología y los valores predictivos de la resonancia magnética para el diagnóstico de Cáncer de Mama durante el periodo 2008- 2012 en el Instituto Nacional de Enfermedades Neoplásicas.
Metodología: Es un estudio observacional descriptivo, siendo el diseño de la investigación es una cohorte retrospectiva, en el cual se estudiarán las historias clínicas y los estudio de resonancia magnética de una población del Instituto Nacional de Enfermedades Neoplásicas con sospecha clínica de cáncer de mama y con estudio previo de mamografía y/o ecografía de mama, para lo cual se obtiene una muestra y los datos fueron procesados mediante programa estadístico SPSS21.
Resultados: Se estudiaron 63 pacientes de sexo femenino con promedio de edad 50 años, de los cuales 59 fueron diagnosticadas como cáncer de mama por resonancia magnética (BIRADS IV y V), de los cuales, 52 sí tuvieron diagnóstico histopatológico de cáncer de mama (prevalencia de 85.7%), obteniendo como valores de predictibidad de 96% de sensibilidad; 22% de especificidad; VVP de 88.1%, VPN de 50% y valor de curva ROC de 69.1%, lo cual indica que la Resonancia magnética de mama tiene fuerte correlación con el diagnóstico de cáncer de mama. Las indicaciones de cáncer de mama más frecuentes fueron la detección de multifocalidad y multicentricidad, la presencia de ganglio axilar (+) para cáncer, con sospecha de cáncer de mama y la caracterización de lesión inconclusa por examen físico, mamografía y ecografía. El tipo de cáncer más frecuente fue el carcinoma ductal infiltrante.
Conclusiones: El diagnóstico de cáncer de mama por Resonancia Magnética se correlacionó significativamente con el diagnóstico de cáncer de mama por anatomía patológica, lo cual se corrobora con otros estudios internacionales la gran utilidad de la resonancia magnética, como método auxiliar en casos debidamente indicados.Trabajo académico
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Vásquez, Yap Sam Aída de Fátima. "PRISM como predictor de mortalidad en la Unidad de Cuidados Intensivos Pediátricos del Instituto Nacional de Salud del Niño, periodo enero – diciembre 2012." Bachelor's thesis, Universidad Nacional Mayor de San Marcos, 2013. https://hdl.handle.net/20.500.12672/14059.
Abstract:
Publicación a texto completo no autorizada por el autorEl documento digital no refiere asesor
Determina si es adecuado el rendimiento del escore PRISM como predictor de mortalidad de los pacientes hospitalizados en la Unidad de Cuidados Intensivos Pediátricos del Instituto Nacional de Salud del Niño. Período Enero-Diciembre del 2012. El estudio es de tipo Epidemiológico, transversal y retrospectivo. Se evaluaron a 400 pacientes las cuales se atendieron en la UCIP del INSN durante el año 2012. Se estimó para las variables cualitativas la frecuencia absoluta y relativa. Para el caso de variables cuantitativas se estimaron las medidas de tendencia central como medias y medidas de dispersión como desviación estándar y rango. La discriminación se evaluó a través del análisis del área bajo la curva ROC (Receiver Operating Characteristic) IC 95%. La calibración fue evaluada con la prueba de Hosmer y Lemeshow. También se calculó el SMR (Standardized Mortality Ratio) con sus correspondientes IC 95%. El análisis se realizó con el programa estadístico SPSS versión 20. El 53.1% de los pacientes fueron de sexo masculino y el 46.9% de sexo femenino, con una edad promedio de 4.2 años (). El tiempo promedio de estancia en la unidad de cuidados intensivos fue 12.4 ± 15.8 días y el tiempo promedio de soporte mediante la ventilación mecánica fue 6.7 ± 8.5 días, el 72.3% requirieron ventilación mecánica. El 17.3% falleció de los cuales el 0.5% se realizó necropsia. Los principales diagnósticos al ingreso y egreso de los pacientes pediátricos fueron problemas postoperatorios (41.5% y 38.4% respectivamente), problemas respiratorios (24.5% y 21.4% respectivamente), Shock séptico (13.1% y 14.9% respectivamente) y problemas neurológicos (5.7% y 5.2% respectivamente). Existe relación entre el diagnóstico de shock séptico (p=0.004), postoperatorios (p<0.001), la presencia de otras enfermedades (p=0.005) al ingreso del paciente y la mortalidad del paciente pediátrico. Asimismo se encuentra relación entre el diagnóstico de Shock séptico (p<0.001), postoperatorios (p<0.001), otras enfermedades (p<0.001) en el paciente al egreso y la mortalidad del paciente pediátrico. El 91.1% de los pacientes tuvo un “Bajo Riesgo”, el 7.1% un “Moderado Riesgo” y el 1.8% “Alto Riesgo”. El estado del paciente pediátrico “Muerto” y “Vivo” se relaciona con el Score PRISM (p<0.001). El área bajo la curva ROC para PRISM fue 0,73 (IC 95% 0.659-0.802), la mortalidad estandarizada fue de 1,047 (IC: 99% de 0,56-1,81) para PRISM. Es adecuado el rendimiento del escore PRISM como predictor de mortalidad de los pacientes hospitalizados en la Unidad de Cuidados Intensivos Pediátricos del INSN-2012, sobre todo con respecto al puntaje >30 y con buen nivel de predicción para el segundo y quinto decil de la mortalidad esperada. La mortalidad estandarizada para este estudio fue1.047 (0.56-1.81). La mortalidad en la categoría de PRISM “>30” fue 71.4%, de “20-29” fue 59.3% y “<20” fue 13%. Existiendo relación estadística entre los valores del score de PRISM con mayor porcentaje de muerte (p<0.001).
Trabajo académico
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Cáceres, Jara Rosa María. "Valores predictivos ecográficos y clínicos para el diagnóstico de macrosomía fetal en gestantes atendidas en el Hospital Nacional Hipólito Unanue durante el periodo 2010-2011." Bachelor's thesis, Universidad Nacional Mayor de San Marcos, 2014. https://hdl.handle.net/20.500.12672/11923.
Abstract:
Publicación a texto completo no autorizada por el autorEl documento digital no refiere asesor
Determina la diferencia entre los valores predictivos ecográficos y clínicos para el diagnóstico de macrosomía fetal en el Hospital Nacional Hipólito Unánue durante el periodo 2010- 2011. Estudio observacional de tipo analítico - comparativo, retrospectivo de corte longitudinal. No se aplicó técnica de muestreo porque se realizó el registro de todos los casos durante el periodo de estudio. El tamaño de muestra fue de 340 pacientes, donde el grupo de estudio y comparativo estuvo conformado de 170 pacientes respectivamente. Para el análisis descriptivo se empleó medidas de tendencia central y de dispersión, frecuencias absolutas y relativas. Para el análisis comparativo se empleó la prueba del chi-cuadrado con un nivel de confianza al 95%, para la validez y/o confirmación de las pruebas diagnósticas se utilizó la sensibilidad, especificidad, valor predictivo positivo y negativo. Entre las características sociodemográfica el 71.2% tenían entre 20 y 34 años, con estado civil conviviente en un 70%, el grado de instrucción fue de nivel secundaria mayormente. Las características maternas evidenciaron que el 48% (83) fueron nulíparas, el 28.9% (50) fueron primíparas y sólo un 1.2% (2) fueron gran multíparas, quienes tuvieron un promedio de talla materna de 1.6±0.1 metros, un promedio de peso de 63.3±10.2 kg, con antecedentes maternos como el tener control prenatal (89.0%) y el antecedente de diabetes (0.3%). Asimismo, la edad gestacional promedio al momento del parto fue 39.0±1.0 semanas, culminando en la mayoría de casos en cesárea (66.8%). Respecto a las características fetales se observó que del sexo masculino fueron el 57.9%, y talla promedio de 51.12±2.2 cm. En la evaluación del valor predictivo de la ecografía para diagnosticar macrosomía fetal se obtuvo una sensibilidad de 77%, una especificidad de 58%, con un valor predictivo positivo 64% y valor predictivo negativo de 71%. La altura uterina (>35 cm) tuvo una sensibilidad para detectar macrosomía del 62% y una especificidad de 61%, con un valor predictivo positivo y negativo de 61% y 62%, respectivamente. El valor predictivo ecográfico es mayor que el valor predictivo clínico en el diagnóstico de macrosomía fetal.
Trabajo académico
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Sadr, Faramarz. "Supervisory model predictive control of building integrated renewable and low carbon energy systems." Thesis, Loughborough University, 2012. https://dspace.lboro.ac.uk/2134/9518.
Abstract:
To reduce fossil fuel consumption and carbon emission in the building sector, renewable and low carbon energy technologies are integrated in building energy systems to supply all or part of the building energy demand. In this research, an optimal supervisory controller is designed to optimize the operational cost and the CO2 emission of the integrated energy systems. For this purpose, the building energy system is defined and its boundary, components (subsystems), inputs and outputs are identified. Then a mathematical model of the components is obtained. For mathematical modelling of the energy system, a unified modelling method is used. With this method, many different building energy systems can be modelled uniformly. Two approaches are used; multi-period optimization and hybrid model predictive control. In both approaches the optimization problem is deterministic, so that at each time step the energy consumption of the building, and the available renewable energy are perfectly predicted for the prediction horizon. The controller is simulated in three different applications. In the first application the controller is used for a system consisting of a micro-combined heat and power system with an auxiliary boiler and a hot water storage tank. In this application the controller reduces the operational cost and CO2 emission by 7.31 percent and 5.19 percent respectively, with respect to the heat led operation. In the second application the controller is used to control a farm electrification system consisting of PV panels, a diesel generator and a battery bank. In this application the operational cost with respect to the common load following strategy is reduced by 3.8 percent. In the third application the controller is used to control a hybrid off-grid power system consisting of PV panels, a battery bank, an electrolyzer, a hydrogen storage tank and a fuel cell. In this application the controller maximizes the total stored energies in the battery bank and the hydrogen storage tank.
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TRAN, TUAN-ANH. "A la recherche du profil predictif du suicidant selon les periodes de la vie : a propos de 364 observations recueillies au c.h. vesoul en 2 ans (1988-1989)." Besançon, 1990. http://www.theses.fr/1990BESA3094.
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Salazar, Vargas Victoriano José. "Valoración predictiva de malignidad en tumoraciones anexiales utilizando ecografía doppler y ecografía bidimensional; en pacientes atendidas en el Servicio de Ginecología del Hospital Nacional Arzobispo Loayza durante el periodo 2007-2009." Bachelor's thesis, Universidad Nacional Mayor de San Marcos, 2010. https://hdl.handle.net/20.500.12672/13452.
Abstract:
Objetivo: Determinar si la evaluación ultrasonográfica Doppler es superior a la evaluación ultrasonográfica convencional bidimensional con contraste de grises para determinar riesgo de malignidad en tumores anexiales Diseño de estudio: Se realizó un estudio transversal retrospectivo descriptivo en el que se incluyó a 220 casos de tumoraciones anexiales, se determinaron los puntajes ecográficos bidimensionales con un score previamente determinado y se realizó la valoración con ultrasonografía Doppler (medición de los índices de resistencia y del patrón de flujo vascular). las características morfológicas de los tumores fueron evaluados en base a un score ya establecido (Ferrazzi et al); se consideró como punto de corte el valor de 8; por debajo del cual se consideró tumoraciones compatibles con patología benigna y valores mayores o iguales a 8 compatibles con patología maligna. Todas las tumoraciones fueron sometidas además a la evaluación con el Ecodoppler y se realizó la determinación de los índices de resistencia (IR) y de la presencia de flujo vascular central o periférico. Se consideró para el IR punto de corte 0.42; valores por debajo de él se consideraron de riesgo para malignidad de manera a priori en base a las revisiones existentes y al protocolo del servicio de ginecología del HNAL. El flujo vascular central se consideró como riesgo de malignidad frente al flujo periférico Resultados: para el análisis de Ecografía bidimensional se aplicó a 220 casos, mientras que los marcadores ecográficos Doppler sólo en 148 casos (porque los 72 restantes no tuvieron vascularización). En el presente trabajo se encontró para el score ecográfico bidimensional una sensibilidad ,especificidad, VPN, VPP y LR de 50%, 84.4%, 41.6% y 88.3% Y 19.77 Por otro lado en la evaluación ecográfica Doppler del Índice de resistencia se encontró una sensibilidad, especificidad, VPN, VPP y LR + de 10%,100%,100%, 75% y 10.77; en ambos casos la prueba de Chi cuadrado resulta significativamente estadístico con p< 0.05. Finalmente en la evaluación ecográfica Doppler del mapeo vascular se encontró una sensibilidad, especificidad, VPN, VPP y LR + de 40%,66.6%,25%, 69.2% y 0.56 con el valor de chi cuadrado no significativo. Conclusión: La ecografía doppler es menos precisa en predecir malignidad en tumoraciones anexiales.Trabajo académico
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Trejo, Lezama Claudia Sofía, and León Enrique Albino Contreras. "CIRCUNFERENCIA DEL CUELLO COMO PREDICTOR DE VÍA AEREA DIFÍCIL EN PACIENTES CON OBESIDAD SOMETIDOS A ANESTESIA GENERAL EN EL HOSPITAL GENERAL DR. GUSTAVO BAZ PRADA EN EL PERIODO COMPRENDIDO DE JULIO A OCTUBRE DE 2013." Tesis de Licenciatura, Medicina-Quimica, 2014. http://ri.uaemex.mx/handle/123456789/14663.
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Higareda, Sánchez Rodolfo, and Estrada Everardo Ibarra. "Flujometría Doppler de las arterias uterinas como predictor de preeclampsia en embarazos de 18-24 semanas de gestación del hospital materno infantil del ISSEMyM en el periodo 1° de enero al 31 de diciembre del 2011." Tesis de Licenciatura, Medicina-Quimica, 2013. http://ri.uaemex.mx/handle/20.500.11799/14044.
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López, Flores Clara Vanessa, and Villafana Antonio Arzate. "Incremento del SOFA como predictor de Mortalidad a 28 días en pacientes Geriátricos admitidos en la Unidad de Terapia Intensiva del Centro Médico ISSEMYM del periodo comprendido del 1° de enero al 30 de junio del 2011." Tesis de Licenciatura, Medicina-Quimica, 2013. http://ri.uaemex.mx/handle/123456789/13883.
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Yamada, Léia Alessandra Pinto. "Avaliação de náuseas e vômitos induzidos por quimioterapia, história de tabagismo e uso crônico de opioides como fatores de risco para náuseas e vômitos no pós-operatório (NVPO) de pacientes oncológicos: estudo observacional prospectivo." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/5/5152/tde-12092018-095229/.
Abstract:
Introdução: Náuseas e vômitos pós-operatórios são queixas importantes no período pós-operatório e seu controle adequado em pacientes oncológicos ainda é um desafio. Na avaliação de fatores de risco relacionados à NVPO é importante melhorar a estratificação dos pacientes a serem submetidos à anestesia e cirurgia, de maneira a propor intervenções que diminuam a NVPO. Neste estudo avaliou-se as variáveis náuseas e vômitos induzidos por quimioterapia (NVIQ), o uso crônico de opioides prévio à cirurgia, a história detalhada de tabagismo e o processo de cessação do tabagismo no período anterior à cirurgia em pacientes oncológicos. Métodos: Foi realizado um estudo observacional, prospectivo de 1829 pacientes oncológicos submetidos à cirurgia oncológicas de médio e grande porte entre maio de 2014 e novembro de 2015 no Instituto do Câncer do Estado de São Paulo (ICESP), Brasil. NVPO foram avaliados nas primeiras 24 horas de pós-operatório. Os dados foram obtidos por meio de entrevistas e de consulta aos prontuários. Foi realizada análise bivariada para estudar os potenciais fatores associados à NVPO. A análise de regressão logística múltipla identificou um novo modelo para previsão de NVPO através do estado de tabagismo detalhado. Resultados: A incidência global de NVPO foi de 30,8%. Houve correlação entre NVPO e as variáveis sexo feminino, idade, não tabagismo, NVIQ e história de cinetose. O risco de NVPO em fumantes foi de 14,1%, de 18,1% naqueles que pararam de fumar até um mês, 24,7% naqueles que pararam de fumar entre um mês e seis meses, 29,4% naqueles que pararam de fumar há mais de seis meses e 33,9% naqueles que nunca fumaram. Esta correlação gerou um novo modelo preditor para previsão de NVPO incluindo o histórico de tabagismo detalhado ao invés da variável dicotômica usada pelo modelo de Apfel, curva ROC com modelo de Apfel - AUC: 63,7% e novo modelo: 67,9%. Não foi encontrada relação entre o tipo de cirurgia e uso opioide crônico com NVPO. Conclusão: As variáveis sexo feminino, idade, não tabagismo, NVIQ, história prévia de cinetose foram confirmadas como fatores de risco para NVPO e um novo modelo preditor foi identificado pela associação entre NVPO e a história tabágica na população oncológicaIntroduction: Nausea and vomiting are the main sources of discomfort in the postoperative period and their adequate control in oncological patients is still defiant. During the evaluation of PONV risk factor it is important to better stratify the patients to be submitted to anesthesia and surgery, in order to propose interventions that lead to the decrease in PONV. In this study, we evaluated chemotherapy induced nausea and vomiting (CINV), chronic use of opioid prior to surgery and the detailed history of smoking and of smoking quitting in oncological patients. Methods: This was an observational prospective study of 1829 oncological patients submitted to surgery from May 2014 and November 2015 in the Institute of Cancer of the State of São Paulo (ICESP), Brazil. PONV was evaluated in the first 24 hours after surgery. The data was obtained by interviews and medical records consultation. Bivariate analysis was performed to study potential factors associated to PONV. Multiple logistics analysis identified a new prediction model to PONV adding detailed smoking status. Results: Incidence of PONV was of 30.8%. There was correlation among PONV and female sex, age, non-smoking, CINV and previous motion sickness. Risk of PONV was of 14.1% in smokers, 18.1% in individuals that quit smoking in less than a month, 24.7% in individuals that quit smoking between one and six months, 29.4% in those who quit smoking more than six months and 33.9% in individuals that never smoked. This correlation generated a new PONV prediction model, including detailed smoking status rather than the Apfel dichotomous variable of smoking (yes/no), ROC curve using Apfel´s model - AUC - 63.7% and new model - 67.9%. There was no correlation between type of surgery, chronic opioid use and PONV. Conclusion: Female sex, age, non-smoking, CINV, previous motion sickness was confirmed as risk factors for PONV and a new PONV prediction model was identified through the association between PONV and the detailed history of smoking and smoking quitting in the oncological population
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Rodríguez, Jave Líz Araceli Sotelo Canahualpa Fiorella Yurico. "Valor predictivo del índice de pulsatilidad promedio de las arterias uterinas en la detección precoz de preeclampsia en las gestantes entre 11 y 14 semanas que acuden a la Unidad de Medicina Fetal del INMP en el periodo de mayo del 2009 a marzo del 2010." Universidad Nacional Mayor de San Marcos. Programa Cybertesis PERÚ, 2011. http://www.cybertesis.edu.pe/sisbib/2011/rodriguez_jl/html/index-frames.html.
38
Rodríguez, Jave Líz Araceli, and Canahualpa Fiorella Yurico Sotelo. "Valor predictivo del índice de pulsatilidad promedio de las arterias uterinas en la detección precoz de preeclampsia en las gestantes entre 11 y 14 semanas que acuden a la Unidad de Medicina Fetal del INMP en el periodo de mayo del 2009 a marzo del 2010." Bachelor's thesis, Universidad Nacional Mayor de San Marcos, 2011. https://hdl.handle.net/20.500.12672/2973.
Abstract:
Introducción: Los trastornos hipertensivos son una de las complicaciones médicas más frecuentes que se producen durante el embarazo, constituyendo un problema de salud pública en todo el mundo. En el Perú se registra entre un 7% y 9% y su importancia radica en que constituye una de las tres primeras causas de mortalidad materna y de restricción del crecimiento intrauterino. En los últimos años, se ha demostrado que un patrón anormal en las ondas velocidad de flujo de las arterias uterinas durante el primer y segundo trimestre del embarazo está relacionado con un mayor riesgo de desarrollar preeclampsia.
Objetivo: Determinar el valor predictivo del índice de pulsatilidad (IP) promedio de las arterias uterinas para el punto de corte mayor o igual al percentil 95 (≥ P95) en la detección precoz de preeclampsia en las gestantes entre 11 y 14 semanas que acudieron a la Unidad de Medicina Fetal del INMP en el periodo de mayo del 2009 a marzo del 2010.
Método: Estudio Analítico de cohortes, retrospectivo, longitudinal.
Resultados: De las 120 pacientes estudiadas, 24 presentaron Hipertensión gestacional (20%), 6 preeclampsia leve (5%) y 4 preeclampsia severa (3.3%). El valor del IP promedio para el percentil 95 fue 2.66. La capacidad predictiva del IP anormal para el punto de corte (IP ≥ 2.66) se determinó por una sensibilidad del 20%, especificidad 96%, VPP 33%, VPN 93%, LR (+) 5.5, LR (–) 0.83, RR (IC 95%) 4.75 (1.28 – 17.68).
Conclusión: El IP promedio de las arterias uterinas para el punto de corte (≥ P95) entre las 11 y 14 semanas de gestación, tiene un excelente valor predictivo en la detección precoz de PreeclampsiaTesis
39
Fedorková, Lucie. "Metody stabilizace nestabilních řešení diskrétní logistické rovnice." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2019. http://www.nusl.cz/ntk/nusl-400443.
Abstract:
Diplomová práce pojednává o stabilizaci diskrétního logistického modelu pomocí několika řídících metod. Je zde provedena především stabilizace rovnováh, 2-periodických cyklů a 3-periodických cyklů. Ke stabilizaci systému je využito proporčního zpětně-vazebního řízení, zpětně-vazebního řízení s časovým zpožděním a řízení založeného na predikci. U každé metody je diskutovaná stabilizační množina pro řídící zesilovač spolu s oblastmi stability pro odpovídající kontrolovaná řešení. Všechny teoretické výsledky jsou ilustrovány grafickými interpretacemi v softwaru MATLAB. Podpůrné výpočty jsou provedeny pomocí softwaru Maple.
40
Šrom, Marek. "Hodnocení úspěšnosti developerského projektu." Master's thesis, Vysoké učení technické v Brně. Fakulta podnikatelská, 2009. http://www.nusl.cz/ntk/nusl-222316.
Abstract:
The master's thesis is focused on evaluation of development project for the purpose of recommendation, how the company should continue with the project in the future. The analysis of the commercial real estate market and evaluation of up-to-date financial results are included. In the practical part, alternatives of selling the project and the prediction of future progress in case of lease-continuation are compared.
41
Svedjemo, Gustaf. "Landscape Dynamics : Spatial analyses of villages and farms on Gotland AD 200-1700." Doctoral thesis, Uppsala universitet, Arkeologi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-219237.
Abstract:
This dissertation deals with the long-term dynamics and fluctuations of settlements on Gotland for the period from AD 200 up until early modern times. The settlement structure on Gotland is most often described as very stable and consisting of solitary farms, established in the Iron Age. A contrasting view is presented by analyses of a vast source material from different periods. The source material consists of both physical remains, noted in the Swedish national Archaeological Sites Information System, FMIS and large scale historical maps, as well as other written sources. For the first studied period, the locations of some 2 000 houses are known, since they were constructed with sturdy stone walls and are thus preserved. The source material for the following periods is scarcer, but some hundred Viking Age sites are identified, mainly by the find places of silver hoards. By retrogressive analyses of historical maps, from the decades around the year 1700, and other written sources, later periods are analysed. All available data are gathered in geodatabases, which enables both generalised and detailed spatial and statistical analyses. The results of the analyses show a more varied picture, with great fluctuations in the number of farms; the existence of villages is also clearly indicated in a large part of the settlements. The villages are centred on kinship and the lack of strong royal power or landed gentry meant they were not fixed in cadastres, as fiscal units, as villages were on the Swedish mainland. Two peaks, followed by major dips, were identified in the number of settlements and thus in the population. The first peak occurred during the late Roman Iron Age/Migration period, which was followed by a reduction in the Vendel period of possibly up to 30-50%. After this, a recovery started in the Viking Age, which culminated during the heydays of Gotland in the High Middle Ages, with population numbers most probably not surpassed until late in history. This upward trend was broken by the diminishing trade of Gotland, the Medieval agrarian crisis, The Danish invasion and later events. All this resulted in a decline, probably as great as after the Migration period.
42
Peñarrocha, Alós Ignacio. "Sensores virtuales para procesos con medidas escasas y retardos temporales." Doctoral thesis, Universitat Politècnica de València, 2008. http://hdl.handle.net/10251/3882.
Abstract:
En este trabajo se aborda el problema de controlar un proceso cuya salida se muestrea de forma irregular. Para ello se propone utilizar un predictor que estima las salidas del proceso en instantes regulares de tiempo más un
controlador convencional que calcula la acción de control a partir de las estimaciones del predictor (técnica conocida como control inferencial).
La predicción consiste en estimar las variables de salida que se desean controlar a partir de las mediciones realizadas con diversos sensores utilizando para ello un modelo matemático del proceso. El filtro de Kalman permite hacer la predicción de forma óptima si las perturbaciones tienen una distribución gaussiana de media cero, pero con el inconveniente de requerir un elevado coste computacional cuando se utilizan diferentes sensores con retardos temporales variantes. En este trabajo se propone una estrategia de predicción alternativa
de bajo coste computacional cuyo diseño se basa en el conocimiento de la disponibilidad de mediciones y de los retardos (del proceso, del sistema de medición o del sistema de transmisión de datos) y de la naturaleza de las
perturbaciones. Los predictores propuestos minimizan el error de predicción frente al muestreo aleatorio con retardos variantes, perturbaciones, ruido de medida, error de modelado, retardos en la acción de control e incertidumbre en los tiempos de medición. Las diferentes estrategias de diseño que se proponen se clasifican según el tipo de información que se dispone de las perturbaciones y del coste computacional requerido.
Se han planteado los diseños para sistemas monovariables, multivariables, lineales y no lineales. Asimismo, también se ha elaborado una forma más eficiente de incluir mediciones escasas con retardo en el filtro de Kalman, con el objetivo de reducir el coste computacional de la predicción.
En este trabajo se demuestra que los sistemas de control inferencial que utilizan los predictores propuestos cumplen con el principio de sepPeñarrocha Alós, I. (2006). Sensores virtuales para procesos con medidas escasas y retardos temporales [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/3882
Palancia
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Smeili, Luciana Andréa Avena. "Determinação de incidência, preditores e escores de risco de complicações cardiovasculares e óbito total, em 30 dias e após 1ano da cirurgia, em pacientes submetidos a cirurgias vasculares arteriais eletivas." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/5/5169/tde-04082015-124607/.
Abstract:
Introdução: Estima-se que ocorram 2,5 milhões de mortes por ano relacionadas a cirurgias não cardíacas e cinco vezes este valor para morbidade, com limitações funcionais e redução na sobrevida em longo prazo. Pacientes que deverão ser submetidos à cirurgia vascular são considerados de risco aumentado para eventos adversos cardiovasculares no pós-operatório. Há, ainda, muitas dúvidas em como fazer uma avaliação pré-operatória mais acurada desses pacientes. Objetivo: Em pacientes submetidos à cirurgia vascular arterial eletiva, avaliar a incidência e preditores de complicações cardiovasculares e/ou óbito total, e calcular a performance dos modelos de estratificação de risco mais utilizados. Métodos: Em pacientes adultos, consecutivos, operados em hospital terciário, determinou-se a incidência de complicações cardiovasculares e óbitos, em 30 dias e em um ano. Comparações univariadas e regressão logística avaliaram os fatores de risco associados com os desfechos e a curva ROC (receiver operating characteristic) examinou a capacidade discriminatória do Índice de Risco Cardíaco Revisado (RCRI) e do Índice de Risco Cardíaco do Grupo de Cirurgia Vascular da New England (VSG-CRI). Resultados: Um total de 141 pacientes (idade média 66 anos, 65% homens) realizou cirurgia de: carótida 15 (10,6%), membros inferiores 65 (46,1%), aorta abdominal 56 (39,7%) e outras (3,5%). Complicações cardiovasculares e óbito ocorreram, respectivamente, em 28 (19,9%) e em 20 (14,2%), em até 30 dias, e em 20 (16,8%) e 10 (8,4%), de 30 dias a um ano. Complicações combinadas ocorreram em 39 (27,7%) pacientes em até 30 dias e em 21 (17,6%) de 30 dias a um ano da cirurgia. Para eventos em até 30 dias, os preditores de risco encontrados foram: idade, obesidade, acidente vascular cerebral, capacidade funcional ruim, cintilografia com hipocaptação transitória, cirurgia aberta, cirurgia de aorta e troponina alterada. Os escores Índice de Risco Cardíaco Revisado (RCRI) e Índice de Risco Cardíaco do Grupo de Estudo Vascular da New England (VSG-CRI) obtiveram AUC (area under curve) de 0,635 e 0,639 para complicações cardiovasculares precoces e 0,562 e 0,610 para óbito em 30 dias, respectivamente. Com base nas variáveis preditoras aqui encontradas, testou-se um novo escore pré-operatório que obteve AUC de 0,747, para complicações cardiovasculares precoces, e um escore intraoperatório que apresentou AUC de 0,840, para óbito em até 30 dias. Para eventos tardios (de 30 dias a 1 ano), os preditores encontrados foram: capacidade funcional ruim, pressão arterial sistólica, cintilografia com hipocaptação transitória, ASA (American Society of Anesthesiologists Physical Status) classe > II, RCRI (AUC 0,726) e troponina alterada. Conclusões: Nesse grupo pequeno e selecionado de pacientes de elevada complexidade clínica, submetidos à cirurgia vascular arterial, a incidência de eventos adversos foi elevada. Para complicações em até 30 dias, mostramos que os índices de avaliação de risco mais utilizados até o momento (RCRI e VSG-CRI) não apresentaram boa performance em nossa amostra. A capacidade preditiva de um escore mais amplo pré-operatório, e uma análise de risco em dois tempos: no pré-operatório e no pós-operatório imediato, como o que simulamos, poderá ser mais efetiva em estimar o risco de complicaçõesIntroduction: Approximately 2.5 million deaths are caused by non-cardiac surgeries per year, while morbidity, represented by functional impairment and a decline in long-term survival, accounts for five times this value. Patients who require a vascular surgery are considered at an increased risk for adverse cardiovascular events in the postoperative period. However, the method for obtaining a more accurate preoperative evaluation in these patients has not yet been determined. Objective: In patients undergoing elective arterial vascular surgery, the incidence and predictors of cardiovascular complications and/or total death were determined and the performance of risk stratification models was assessed. Methods: The incidence of cardiovascular complications and death within 30 days and 1 year after vascular surgery was determined in consecutive adult patients operated in a tertiary hospital. Univariate comparison and logistic regression analysis were used to evaluate risk factors associated with the outcome, and the receiver operating characteristic (ROC) curve determined the discriminatory capacity of the Revised Cardiac Risk Index (RCRI) and the Cardiac Risk Index of the New England Vascular Surgery Group (VSG-CRI). Results: In all, 141 patients (mean age, 66 years; 65% men) underwent vascular surgery, namely for the carotid arteries (15 [10.6%]), inferior limbs (65 [46.1%]), abdominal aorta (56 [39.7%]), and others (5 [3.5%]). Cardiovascular complications and death occurred in 28 (19.9%) and 20 (14.2%) patients, respectively, within 30 days after surgery, and in 20 (16.8%) and 10 (8.4%) patients, respectively, between 30 days and 1 year after the surgical procedure. Combined complications occurred in 39 patients (27.7%) within 30 days and in 21 patients (17.6%) between 30 days and 1 year after surgery. The risk predictors for cardiovascular events that occurred within 30 days were age, obesity, stroke, poor functional capacity, transitory myocardial hypocaptation on scintigraphy, open surgery, aortic surgery, and abnormal troponin levels. The RCRI and VSG-CRI showed an under the curve area of 0.635 and 0.639 for early cardiovascular complications as well as of 0.562 and 0.610 for death within 30 days, respectively. Based on the predictors found in this study, a new preoperative score was proposed, based on an AUC of 0.747 obtained for early cardiovascular complications and an intraoperative score that presented an AUC of 0.840 for death within 30 days. For late events (between 30 days and 1 year), the predictors were poor functional capacity, systolic blood pressure, presence of transitory myocardial hypocaptation on scintigraphy, class > II American Society of Anesthesiologists Physical Status score, RCRI (AUC= 0.726), and abnormal troponin levels. Conclusions: In this small group of patients with increased clinical complexity who underwent arterial surgery, the incidence of adverse events was high. In our series, we found that RCRI and VSG-CRI do not reasonably predict the risk of cardiovascular complications. The predictive capacity of a modified preoperative score and evaluating the risk preoperatively and early postoperatively, such as that simulated in this study, may be more effective in determining the risk of complications
44
Chen, Bing-Chuan, and 陳炳全. "Prediction for Non Periodic Hospital Building Maintenance Cost by Using Markov Chain." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/86968330766959981537.
Abstract:
碩士國立臺灣大學
土木工程學研究所
97
The architectural functions of a hospital building are more complex than commercial or residential building. Once the hospital building maintenance is neglected, not only will there be a high cost of repair but also a loss of human lives. A recent accident at National Taiwan University Hospital (NTUH) has revealed the significance of hospital building maintenance. For providing long-term medical services, the hospital equipments play an irreplaceable role in quality assurance of medical care. As the economy suffers in recent years, the government’s fund for hospital preservation also declines. Consequently, there is an increase in difficulty to manage a hospital. A few publications have initiated interviews and surveys, but lacks of historical records for prediction. Using the East Site of Taiwan National University as the case study, this research analyzes the current hospital building maintenance record and predicts non-periodical maintenance cost for future. Markov Process is a prediction method that utilizes present information to describe future condition. The future condition is assumed by reviewing the changes of the past years. With detail review of 5,028 records of hospital building maintenance over the last ten years, this study proposes a cost prediction model for non-periodical maintenance by using Markov Chain as the methodology. Variables including frequency and cost are also taken into consideration to enhance accuracy. This hospital building maintenance prediction model could be a reference for hospital management to budget more effectively for the coming year. It can also check the rationality of present budget mechanism.
45
Wong, Mun-Hou, and 黃文浩. "Long-Term User Location Prediction Using Deep Learning and Periodic Pattern Mining." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/825dbn.
Abstract:
碩士國立交通大學
資訊科學與工程研究所
105
In recent years, with the advances in mobile communication and growing popularity of the fourth-generation mobile network along with the enhancement in location positioning techniques, mobile devices have generated extensive spatial trajectory data, which represent the mobility of moving objects. New services are emerged to serve mobile users based on their predicted locations. This thesis is concerned with the long-term location prediction of a user. Most of the existing studies on location prediction can only predict one next location of a user, which is regarded as short-term next location prediction, and they are not applicable for long-term location predictions. We believe that if we can improve the accuracy of long-term next location prediction predict, every current service that takes benefits of predictability on next location can be further extended. In this thesis, we propose a prediction framework named LSTM-PPM that utilises deep learning and periodic pattern mining for effective long-term location prediction. Our framework devises the ideology from natural language model and uses multi-step recursive strategy to perform long-term prediction. To reduce the accumulated loss in multi-step strategy, we utilise further the periodic pattern mining technique. Through empirical evaluation on a real-life trajectory data, our framework is shown to provide effective performance in long-term location prediction.
46
Wong, Geraldine H. "Drought predictions: applications in Australia." Thesis, 2010. http://hdl.handle.net/2440/64290.
Abstract:
Drought is a global and recurrent natural phenomenon, the inevitable consequence of meteorological variability. This natural hazard brings about devastating effects because water is one of the most fundamental commodities for human survival, and a lack of water can result in varying consequences, from mere inconvenience to life threatening instances. Drought cannot be prevented but its effects can be mitigated through the design of appropriate water resource infrastructure and management strategies. The goal of this thesis is to model the spatial and temporal characteristics of drought occurrence in Australia, the driest continent. In doing so predictions can be made, levels of risk can be evaluated and conditional estimates of drought can be based on climatic state variables.
For insight into the nature of drought in Australia, multivariate models of drought characteristics are developed. Preliminary analysis demonstrates high correlations between several drought characteristics, these are the drought severity, intensity and duration. This thesis applies the copula concept, which is a versatile means of modelling their dependence
structure. Copulas are multivariate uniform distributions, which allow the joint behaviour of variables to be modelled independently from their marginal distributions. This research
extends the application of copulas by investigating the effect of climate variability on copula models and subsequent drought characteristics. Two different copula families are fitted to the drought characteristics to demonstrate the importance of tail dependence when modelling extreme climatic events. An important application of these models is the calculation of return periods of extreme drought events exceeding certain thresholds, taking account of variability in climatic indices.
A second objective is to forecast drought at various spatial resolutions. The most straightforward method are regression and ARMA models that incorporate global climatic indicators. The effect of climatic variation on Australia's precipitation is examined by investigating the association between climatic indices and the multivariate distribution of drought at numerous sites across Australia. Two classification strategies for forecasting rainfall are compared using significance testing based on multiple comparison techniques. Further to this, rainfall forecasting relationships are explored using global sea-surface temperature anomalies.
The versatility of copula models is demonstrated through short-term rainfall predictions for neighbouring rainfall districts, using separate copulas conditioned on antecedent climate
conditions. This technique is shown to improve rainfall predictions in neighbouring districts and improve estimates of drought probability.Thesis (Ph.D.) -- University of Adelaide, School of Mathematical Sciences, 2010
47
Ulhaq, Richa Etika, and 烏堤卡. "Three-Year Periods Watchdog Events for Predicting Crisis Phase Using Taiwan Listed Companies Dataset." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/2a6qc2.
Abstract:
碩士國立中央大學
資訊工程學系
107
While many studies focused on predicting bankruptcy by using financial ratios or combining them with corporate governance indicators, this study pursue a crisis events which causes lose to a company to predict their first crisis which can be an initial step to prevent them to be bankrupt in the future. Recorded events information-gathered by watchdog dataset of Taiwan listed companies-before the financial crisis happened in a company can be used to predict financial crisis in a company. This study focus on the prediction start from three year periods before first crisis happened in a company using statistical and machine learning method which is motivated with the research question: could the chosen watchdog events help to improve the performance of crisis prediction start from three years before first crisis? To acknowledge this question, a proposed model is built by a combination of financial ratios and five events gathered by watchdog using Taiwan listed companies.
48
"Integrated Predictive Model for Healing and Fatigue Endurance Limit for Asphalt Concrete." Doctoral diss., 2012. http://hdl.handle.net/2286/R.I.14701.
Abstract:
abstract: One of the main requirements of designing perpetual pavements is to determine the endurance limit of Hot Mix Asphalt (HMA). The purpose of this study was to validate the endurance limit for HMA using laboratory beam fatigue tests. A mathematical procedure was developed to determine the endurance limit of HMA due to healing that occurs during the rest periods between loading cycles. Relating healing to endurance limit makes this procedure unique compared to previous research projects that investigated these concepts separately. An extensive laboratory testing program, including 468 beam tests, was conducted according to AASHTO T321-03 test procedure. Six factors that affect the fatigue response of HMA were evaluated: binder type, binder content, air voids, test temperature, rest period and applied strain. The endurance limit was determined when no accumulated damage occurred indicating complete healing. Based on the test results, a first generation predictive model was developed to relate stiffness ratio to material properties. A second generation stiffness ratio model was also developed by replacing four factors (binder type, binder content, air voids, and temperature) with the initial stiffness of the mixture, which is a basic material property. The model also accounts for the nonlinear effects of the rest period and the applied strain on the healing and endurance limit. A third generation model was then developed by incorporation the number of loading cycles at different locations along the fatigue degradation curve for each test in order to account for the nonlinearity between stiffness ratio and loading cycles. In addition to predicting endurance limit, the model has the ability to predict the number of cycles to failure at any rest period and stiffness combination. The model was used to predict fatigue relationship curves for tests with rest period and determining the K1, K2, and K3 fatigue cracking coefficients. The three generation models predicted close endurance limit values ranging from 22 to 204 micro strains. After developing the third generation stiffness ratio model, the predicted endurance limit values were integrated in the strain-Nf fatigue relationships as a step toward incorporating the endurance limit in the MEPDG software. The results of this study can be used to design perpetual pavements that can sustain a large number of loads if traffic volumes and vehicle weights are controlled.Dissertation/Thesis
Ph.D. Civil and Environmental Engineering 2012
49
LU, CHI-CHUN, and 盧其君. "A Comparative Analysis of the Establishment of Stock Prediction Model based on the Fama-French Three Factor Model of Pre- and Post-financial Tsunami Periods." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/hjndf5.
Abstract:
碩士國立臺北大學
國際財務金融碩士在職專班
104
This study investigates the impacts of the Fama-French three-factor model, market and financial information on individual stock returns. In addition, the study also investigates and compares the differences between pre- and post 2008 financial Tsunami periods. Annual data, ranging from 2003 to 2014, were collected from the top 100 listed companies using Taiwan Economic Journal database. Multiple regression analysis is employed to analyze the full sample, pre- and post- the Financial Tsunami periods. The empirical findings are summarized as follows: First, both the annual rate of return of Taiwan Stock Weighted Index and P/B ratio have significant impacts on stock returns. Secondly, the financial information such as dividend yield, the annual turnover rate, revenue growth, net income growth rates have significant impacts on stock returns. Thirdly, the comparison between the pre- and post- the financial Tsunami, financial information such as dividend yield, the annual turnover rate, the return on assets, revenue growth, net income growth rates have significant impacts on stock returns
50
Bandarabadi, Mojtaba. "Low-complexity measures for epileptic seizure prediction and early detection based on classification." Doctoral thesis, 2015. http://hdl.handle.net/10316/27608.
Abstract:
Tese de doutoramento em Ciência da Informação e Tecnologia, apresentada ao Departamento de Engenharia Informática da Faculdade de Ciências e Tecnologia da Universidade de CoimbraThis thesis concerns the problems of epileptic seizure prediction and detection. We analyzed multichannel intracranial electroencephalogram (iEEG) and surface electroencephalogram (sEEG) recordings of patients suffering from refractory epilepsy, to access the brain state in real time by using relevant EEG features and computational intelligence techniques, and aiming for detection of pre-seizure state (in the case of prediction) or seizure onset times (in the case of detection). Our main original contribution is the development of a novel relative bivariate spectral power feature to track gradual transient changes prior to ictal events for real-time seizure prediction. Furthermore a novel robust and generalized measure for early seizure detection is developed, aimed to be used in closed-loop neurostimulation systems. The development of a general platform embeddable on a transportable low-power-budget device is of utmost importance, for real time warning to patients and their relatives about the impending seizure or beginning of an occurring seizure. The portable device can also be integrated to work in conjunction with a closed-loop neurostimulation or fast-acting drug injection mechanism to eventually disarm the impending seizure or to suppress the just-occurring seizure. Therefore, in this thesis we try to meet the dual-objective of developing algorithms for seizure prediction and early seizure detection that provide high sensitivity and low number of false alarms, fulfilling the requirements of clinical applications, while being low computational cost. To seek the first objective, a patient-specific seizure prediction was developed based on the extraction of novel relative bivariate spectral power features, which were then preprocessed, dimensionally reduced, and classified using a machine-learning algorithm. The introduced feature bears low complexity, and was discriminated using the powerful support vector machine (SVM) classifier. We analyzed the preictal EEG dynamics across different brain regions and throughout several frequency bands, using relative bivariate features to uncover the underlying mechanisms ending in epileptic seizures. The suggested prediction system was evaluated on long-term continuous sEEG and iEEG recordings of 24 patients, and produced statistically significant results with average sensitivity of 75.8% and false prediction rate of 0.1 per hour. Furthermore a novel statistical method was developed for proper selection of preictal period, and also for the evaluation of predictive capability of features, as well as for the predictability of seizures. The method uses amplitude distribution histograms (ADHs) of the features extracted from the preictal and interictal iEEG and sEEG recordings, and then calculates a criterion of discriminability among two classes. The method was evaluated on spectral power features extracted from monopolar and bipolar iEEG and sEEG recordings of 18 patients, in overall consisting of 94 epileptic seizures. To approach the objective of early seizure detection, we have formulated power spectral density (PSD) of bipolar EEG signal in the form of a measure of neuronal potential similarity (NPS) between two EEG signals. This measure encompasses the phase and amplitude similarities of two EEG channels in a simultaneous fashion. The NPS measure was then studied in several narrow frequency bands to find out the most relevant sub-bands involved in seizure initiations, and the best performing ratio of two NPS measures for seizure onset detection was determined. Evaluating on long-term continuous iEEG recordings of 11 patients with refractory partial epilepsy (overall of 1785 h and 183 seizures) the results showed high performance, while requiring a very low computational cost. On average, we could achieve a sensitivity of 86.3%, a low false detection rate (FDR) of 0.048/h, and a mean detection latency of 14.2s from electrographic seizure onsets, while in average preceding clinical onsets by 1.1s. Apart from the above mentioned primary objectives, we introduced two new and robust methods for offline or real-time labelling of epileptic seizures in long-term continuous EEG recordings for further studies. Methods include mean phase coherence estimated from bandpass filtered iEEG signals in specific frequency bands, and singular value decomposition (SVD) of bipolar iEEG signals. Both methods were evaluated on the same dataset employed in the previous study and demonstrated sensitivity of 84.2% and FDR of 0.09/h for sub-band mean phase coherence, and sensitivity of 84.1% and FDR of 0.05/h for bipolar SVD, on average. Most of this work was established in collaboration with the EPILEPSIAE project, aimed to predict of pharmacoresistant epileptic seizures. The developed methods in this thesis were evaluated by the accessibility of long-term continuous multichannel EEG recordings of more than 275 patients with refractory epilepsy, referred to as The European Epilepsy Database. This database was collected by the three clinical centers involved in EPILEPSIAE, and contains well-documented metadata. The results of this thesis are backing the hypothesis of the predictability of most of epileptic seizures using linear bivariate spectral-temporal brain dynamics. Moreover, the promising results of early seizure detection sustain the feasibility of integrating the proposed method with closed-loop neurostimulation systems. We hope the developed methods could be a step forward towards the clinical applications of seizure prediction and onset detection algorithms.
Esta tese versa os problemas de predição e de deteção de crises epiléticas. Analisa-se o eletroencefalograma multicanal intracraniano (iEEG) e de superfície (sEEG) de pacientes que sofrem de epilepsia refratária, para a estimação em tempo real do estado cerebral, usando características relevantes do EEG e técnicas de inteligência computacional, ambicionando a deteção do estado pré-ictal (no caso de previsão) ou dos instantes de início de uma crise (no caso de deteção). A principal contribuição original é o desenvolvimento de uma característica de potência espectral bivariada relativa para captar as mudanças transitórias graduais que levam a crises e que poderão ser usadas para previsão em tempo real. Além disso, é desenvolvida uma nova medida, robusta e generalizada para a deteção precoce, destinada a ser utilizada em sistemas de neuro estimulação em malha fechada. O desenvolvimento de uma plataforma geral possível de ser integrada num dispositivo transportável, energeticamente económico, é de grande relevância para o aviso em tempo real do doente e dos seus próximos sobre a eminência da ocorrência de uma crise. O dispositivo transportável também pode ser usado em malha fechada com um neuro estimulador ou com um dispositivo de injeção rápida de um fármaco que desarme eventualmente a crise em curso. Por isso nesta tese persegue-se o objectivo de desenvolver algoritmos para previsão mas também para deteção de crises. Em ambos os casos, pretende-se que os algoritmos tenham uma elevada sensibilidade e uma baixa taxa de falsos positivos, tornando viável a sua utilização clínica. Para o objectivo de previsão, desenvolveu-se um método de previsão personalizado baseado na extração de uma característica nova, denominada de potência relativa espectral bivariada, que foi submetida a pre-processamento, redução de dimensão e classificação com Máquinas de Vetores de Suporte (SVM). Esta nova característica, de baixa complexidade, é computacionalmente simples, mas permite a análise da dinâmica do EEG preictal em diferentes regiões do cérebro e ao longo de várias bandas de frequência, de modo a descobrir os mecanismos subjacentes às crises epiléticas. O sistema de previsão obtido foi avaliado em registos contínuos de sEEG e iEEG de 24 pacientes, e produziu resultados estatisticamente significativos com sensibilidade média de 75.8% e taxa de predição falsa de 0.1 por hora. Além disso, foi desenvolvido um novo método estatístico para a seleção apropriada do período preictal, e também para a avaliação da capacidade preditiva das características, assim como para a própria previsibilidade das crises. O método utiliza os histogramas de distribuição de amplitude (ADHS) das características extraídas nos períodos pré-ictal e ictal dos registos de iEEG e sEEG e, em seguida, calcula um critério de discriminabilidade entre as duas classes. O método foi avaliado nas características de potencia espectral extraídas de registos iEEG e sEEG, monopolares e bipolares de 18 pacientes, consistindo num número total de crises epilépticas de 94. O segundo objetivo, a deteção precoce de crises, foi abordado através da formulação da densidade de potência espectral (PSD) de canais de EEG bipolares na forma de uma medida da similaridade do potencial neuronal (NPS) entre dois sinais de EEG. Esta medida usa as similaridades entre as fases e as amplitudes de dois canais de EEG de um modo simultâneo. A medida NPS foi estudada em várias bandas estreitas de frequência de modo a descobrir-se quais as sub-bandas mais envolvidas na inicialização das crises; buscou-se assim a melhor razão entre duas NPS do ponto de vista da deteção precoce. Avaliadas em iEEG contínuos de longa duração de 11 doentes com epilepsia refratária parcial (num total de 1785 h e 183 crises), os resultados apresentam um desempenho com sensibilidade de 86.3% e taxa de deteção falsa (FDR) de 0.048/h, uma latência de 14.2s em relação ao início eletrográfico, sendo uma crise detetada em média 1.1s antes da sua manifestação clínica. Para além dos objetivos principais referidos acima, introduziram-se dois novos métodos, robustos, para etiquetagem em diferido e em tempo real das crises em registos contínuos de EEG de longa duração para estudos posteriores. Esses métodos incluem a coerência de fase média (mean phase coherence) estimada a partir de registos iEEG em bandas de frequência específicas (usando filtros passa-banda), e a decomposição em valores singulares (SVD) de sinais iEEG bipolares. Ambos os métodos foram avaliados no mesmo conjunto de dados do estudo anterior e apresentaram, em média, uma sensibilidade de 84.2% e um FDR de 0.09/h para a coerência de fase média calculada para as sub-bandas, e sensibilidade de 84.1% e FDR de 0.05/h para a metodologia que usa a decomposição SVD bipolar. Grande parte deste trabalho foi feito no âmbito do projeto EPILEPSIAE, visando a previsão de crises em doentes epiléticos fármaco-resistentes. Os métodos desenvolvidos nesta tese aproveitaram a acessibilidade aos dados bem documentados de mais de 275 pacientes que constituem a Base de Dados Europeia de Epilepsia (European Epilepsy Database), provenientes dos três centros hospitalares participantes no projeto. Os resultados desta tese apoiam a hipótese da previsibilidade da maioria das crises epiléticas usando dinâmicas cerebrais bivariadas lineares espetrais e temporais. Além disso os resultados são promissores relativamente à deteção precoce de crises e sustentam a fazibilidade da integração desses métodos com técnicas de neuroestimulação em malha fechada. Esperamos que os métodos desenvolvidos resultem num avanço no que respeita à aplicação clínica de algoritmos de previsão e deteção de crises.
FCT - SFRH/BD/71497/2010