• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 404
  • 189
  • 85
  • 72
  • 53
  • 27
  • 21
  • 12
  • 10
  • 8
  • 7
  • 6
  • 6
  • 6
  • 4
  • Tagged with
  • 1076
  • 169
  • 108
  • 97
  • 96
  • 91
  • 80
  • 80
  • 75
  • 72
  • 70
  • 69
  • 63
  • 63
  • 63
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
51

Guaranteed SLAM : an interval approach

Mustafa, Mohamed January 2017 (has links)
The mapping problem is a major player in mobile robotics, and it is essential for many real applications such as disaster response or nuclear decommissioning. Generally, the robotic mapping is addressed under the umbrella of simultaneous localization and mapping (SLAM). Several probabilistic techniques were developed in the literature to approach the SLAM problem, and despite the good performance, their convergence proof is only limited to linear Gaussian models. This thesis proposes an interval SLAM (i-SLAM) algorithm as a new approach that addresses the robotic mapping problem in the context of interval methods. The noise of the robot sensor is assumed bounded, and without any prior knowledge of its distribution, we specify soft conditions that guarantee the convergence of robotic mapping for the case of nonlinear models with non-Gaussian noise. A new theory about compact sets is developed in the context of real analysis to conclude such conditions. Then, a case study is presented where the performance of i-SLAM is compared to the probabilistic counterparts in terms of accuracy and efficiency. Moreover, this work presents an application for i-SLAM using an RGB-D sensor that operates in unknown environments. Interval methods and computer vision techniques are employed to extract planar landmarks in the environment. Then, a new hybrid data association approach is developed using a modified version of bag-of-features method to uniquely identify different landmarks across timesteps. Finally, the results obtained using the proposed data association approach are compared to the typical least-squares approaches, thus demonstrating the consistency and accuracy of the proposed approach.
52

The effects of insect on soft tissue decomposition

Fasano, Ann D. January 2013 (has links)
A primary goal of the forensic anthropologist is assisting in the estimation of a post-mortem interval. This assessment is largely based upon the degree and quality of soft tissue decomposition, influenced by factors including temperature, humidity, insect activity, carnivore and rodent activity, perimortem trauma and the depositional environment. While the effects of temperature on decomposition have been long appreciated and initially studied, little or no research has been conducted on the disruption of insect activity and how that disturbance may affect the decomposition process. This study was designed to determine if the exposure of skin surface of porcine remains to insect repellant (specifically, DEET) has an effect on the presence and overall activity of insects during decomposition. Two experiments were conducted in the spring and fall with results indicating that insect repellant slows the rate of decomposition. Such findings are important for criminal investigators requiring an accurate estimation of post-mortem time to appreciate those factors that may adversely affect the process and rate of soft tissue deterioration.
53

Adipocere and post-mortem interval: multiple variables for consideration and study

Murray, Claudine B. January 2013 (has links)
Thesis (M.S.F.S.) PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you. / This thesis looks at and analyzes the current body of research into the early-stage formation of adipocere as it pertains to post-mortem interval determination. Adipocere is a waxlike substance that can encase bodies after death if certain conditions are met: temperature, moisture content, other environmental factors, and the presence of bacteria that transform fatty acids into the hydroxy- and oxy-fatty acids that make up much of the adipocere substance. Adipocere formation arrests the process of decomposition, making it difficult for forensic pathologists to determine a post-mortem interval. The thesis identifies several issues with current research into early-stage adipocere. Firstly, the majority of scientific papers on the subject make use of pig adipose as a stand-in for human adipose due to ethical concerns. However, this traditional forensic method is not suited for studies into adipocere formation: the fatty acid profiles of pigs and humans have differing ratios of saturated and unsaturated fatty acids, making them an unreliable analog for adipocere testing. In addition, most studies assume a three-month timeframe for the formation process when preparing their experimental design, a timeframe thrown into question by both current data and several existing case studies demonstrating more rapid adipocere formation. Lastly, testing takes place in static environments, which does not reflect actual field conditions. There have been cases that suggest adipocere formation ceases during colder months once decomposition has initially halted. In these cases, the adipocere formation begins again once temperatures return to 22°C or higher. Another issue noted is the lack of chemical analysis conducted on early-formation adipocere. The changes in fatty acid ratios that take place during the process are not typically looked at by scientists investigating the phenomenon or forensic pathologists dealing with adipocere cases, but may offer a viable means of narrowing down post-mortem intervals and contribute to better timelines for pathologists and law enforcement. This thesis ultimately recommends a number of additional research directions necessary for building a temperature zone-based database of case and laboratory results, particularly ones that take into account the variable formation timeframe observed in previous experiments and case studies. / 2031-01-01
54

Analýza poruch reprodukce u dojnic s absencí říje

Křivánková, Petra January 2009 (has links)
No description available.
55

Estudo sobre resolucao de equacoes de coeficientes intervalares / An study about solving equations of interval coefficients

Korzenowski, Heidi January 1994 (has links)
O objetivo deste trabalho e determinar a solução de algumas equações de coeficientes intervalares. Este estudo utiliza uma Teoria das Aproximações Intervalares, a qual foi descrita por [ACI91]. Nesta teoria a igualdade para intervalos e substituída pela relação de aproximação . Esta substituição deve-se ao fato da igualdade utilizada na Teoria Clássica dos Intervalos para resolução de equações de coeficientes intervalares não apresentar uma solução satisfatória, visto que a solução encontrada não contem todas as soluções das equações reais que compõe a equação intervalar. Pela substituição da igualdade intervalar por uma relação de aproximação é possível determinar a solução de equações de coeficientes intervalares, de maneira que esta solução contenha todas as possíveis soluções das equações reais pertencentes a equação intervalar. Apresenta-se alguns conceitos básicos, bem como analisa-se algumas propriedades no espaço solução ( /(R), +, •, C, 1). São representadas graficamente diferentes tipos de funções neste espaço intervalar, com os objetivos de obtenção da imagem, caracterização da solução e identificação gráfica da região de solução (ótima e externa), para cada tipo de função. Como a representação de intervalos de /(R) esta determinada num semiplano de eixos X - X+, onde X - representa o extremo inferior de cada intervalo e X+ representa o extremo superior dos intervalos, apresenta-se o espaço intervalar estendido /(R). Neste espaço intervalar estão definidos os intervalos não-regulares, representados no outro semi-piano de eixos X - X+ Em /(R) serão apresentados alguns conceitos fundamentais, assim como operações aritméticas e algumas considerações referentes aos intervalos não-regulares. No espaço intervalar /(R) e possível resolver equações de coeficientes intervalares de maneira análoga a resolução de equações reais no espaço real, pois este espaço intervalar possui a estrutura semelhante a de um corpo. Com isto apresenta-se a solução de equações de coeficientes intervalares lineares, obtida diretamente, assim como determina-se a Formula de Bascara Intervalar para resolução da Equação Quadrática Intervalar. Para funções que possuem grau maior que 2 apresenta-se alguns métodos iterativos intervalares, tais como o Método de Newton Intervalar, o Método da Secante Intervalar e o Método híbrido Intervalar, que permitem a obtenção do intervalo solução para funções intervalares. Por fim apresenta-se alguns conceitos básicos no espaço intervalar matricial M„,„(/(R)), bem como apresenta-se alguns métodos diretos para resolução de sistemas de equações lineares intervalares. / The aim of this work is to determine the solution set of some Equations of Interval Coefficients. The study use a Theory of Interval Approximation. The begining of this theory was described by [ACI91]. In this theory the equality for intervals is replaced by an approximation relation. When we make use of that relation to solve interval equations, it's possible to obtain an optimal solution, i.e., to get an interval solution that contain all of real solutions of the real equations envolved in the interval equation. By using the equality of Classical Interval Theory for solving interval equations we can not get an optimal solution, that is, the interval solution in the most of equations not consider some real solutions of real equations that belong to the interval equation. We present some basic concepts and analyse some properties at the interval space (1(R), E, -a x , 1). Different kind of functions are showed in this space in order to obtain the range, the solution caracterization and the graphic identification of the optimal and external solution region, for each kind of function. The representation of intervals in /(R) is determined in a half plane of axes X - , X+, where X - represent the lower endpoint and X+ represent the upper endpoint of the intervals. The nonregular intervals are defined in /(R), which are determined in an other half plane. In this interval space are presenting some specific concepts, as well as arithmetical operations and some remarks about nonregular intervals. The interval space (1(R), +, •, C, Ex , 1) have a similar structure to a field, so it's possible to solve interval coefficients equations analogously as to solve real equations in the real space. We present the solution of linear interval equations and we determine an interval formula to solve square interval equation. We present some intervals iterated methods for functions that have degree greater than 2 that allow to get an interval solution of interval functions. Finally we show some basic concepts about the interval matrix space Af,„„(IR)) and present direct methods for the resolution of linear interval sistems.
56

Estudo sobre resolucao de equacoes de coeficientes intervalares / An study about solving equations of interval coefficients

Korzenowski, Heidi January 1994 (has links)
O objetivo deste trabalho e determinar a solução de algumas equações de coeficientes intervalares. Este estudo utiliza uma Teoria das Aproximações Intervalares, a qual foi descrita por [ACI91]. Nesta teoria a igualdade para intervalos e substituída pela relação de aproximação . Esta substituição deve-se ao fato da igualdade utilizada na Teoria Clássica dos Intervalos para resolução de equações de coeficientes intervalares não apresentar uma solução satisfatória, visto que a solução encontrada não contem todas as soluções das equações reais que compõe a equação intervalar. Pela substituição da igualdade intervalar por uma relação de aproximação é possível determinar a solução de equações de coeficientes intervalares, de maneira que esta solução contenha todas as possíveis soluções das equações reais pertencentes a equação intervalar. Apresenta-se alguns conceitos básicos, bem como analisa-se algumas propriedades no espaço solução ( /(R), +, •, C, 1). São representadas graficamente diferentes tipos de funções neste espaço intervalar, com os objetivos de obtenção da imagem, caracterização da solução e identificação gráfica da região de solução (ótima e externa), para cada tipo de função. Como a representação de intervalos de /(R) esta determinada num semiplano de eixos X - X+, onde X - representa o extremo inferior de cada intervalo e X+ representa o extremo superior dos intervalos, apresenta-se o espaço intervalar estendido /(R). Neste espaço intervalar estão definidos os intervalos não-regulares, representados no outro semi-piano de eixos X - X+ Em /(R) serão apresentados alguns conceitos fundamentais, assim como operações aritméticas e algumas considerações referentes aos intervalos não-regulares. No espaço intervalar /(R) e possível resolver equações de coeficientes intervalares de maneira análoga a resolução de equações reais no espaço real, pois este espaço intervalar possui a estrutura semelhante a de um corpo. Com isto apresenta-se a solução de equações de coeficientes intervalares lineares, obtida diretamente, assim como determina-se a Formula de Bascara Intervalar para resolução da Equação Quadrática Intervalar. Para funções que possuem grau maior que 2 apresenta-se alguns métodos iterativos intervalares, tais como o Método de Newton Intervalar, o Método da Secante Intervalar e o Método híbrido Intervalar, que permitem a obtenção do intervalo solução para funções intervalares. Por fim apresenta-se alguns conceitos básicos no espaço intervalar matricial M„,„(/(R)), bem como apresenta-se alguns métodos diretos para resolução de sistemas de equações lineares intervalares. / The aim of this work is to determine the solution set of some Equations of Interval Coefficients. The study use a Theory of Interval Approximation. The begining of this theory was described by [ACI91]. In this theory the equality for intervals is replaced by an approximation relation. When we make use of that relation to solve interval equations, it's possible to obtain an optimal solution, i.e., to get an interval solution that contain all of real solutions of the real equations envolved in the interval equation. By using the equality of Classical Interval Theory for solving interval equations we can not get an optimal solution, that is, the interval solution in the most of equations not consider some real solutions of real equations that belong to the interval equation. We present some basic concepts and analyse some properties at the interval space (1(R), E, -a x , 1). Different kind of functions are showed in this space in order to obtain the range, the solution caracterization and the graphic identification of the optimal and external solution region, for each kind of function. The representation of intervals in /(R) is determined in a half plane of axes X - , X+, where X - represent the lower endpoint and X+ represent the upper endpoint of the intervals. The nonregular intervals are defined in /(R), which are determined in an other half plane. In this interval space are presenting some specific concepts, as well as arithmetical operations and some remarks about nonregular intervals. The interval space (1(R), +, •, C, Ex , 1) have a similar structure to a field, so it's possible to solve interval coefficients equations analogously as to solve real equations in the real space. We present the solution of linear interval equations and we determine an interval formula to solve square interval equation. We present some intervals iterated methods for functions that have degree greater than 2 that allow to get an interval solution of interval functions. Finally we show some basic concepts about the interval matrix space Af,„„(IR)) and present direct methods for the resolution of linear interval sistems.
57

Uncertainty management for coastal defence systems

Hall, James William January 1999 (has links)
No description available.
58

Obtaining Accurate Estimates of the Mediated Effect with and without Prior Information

January 2014 (has links)
abstract: Research methods based on the frequentist philosophy use prior information in a priori power calculations and when determining the necessary sample size for the detection of an effect, but not in statistical analyses. Bayesian methods incorporate prior knowledge into the statistical analysis in the form of a prior distribution. When prior information about a relationship is available, the estimates obtained could differ drastically depending on the choice of Bayesian or frequentist method. Study 1 in this project compared the performance of five methods for obtaining interval estimates of the mediated effect in terms of coverage, Type I error rate, empirical power, interval imbalance, and interval width at N = 20, 40, 60, 100 and 500. In Study 1, Bayesian methods with informative prior distributions performed almost identically to Bayesian methods with diffuse prior distributions, and had more power than normal theory confidence limits, lower Type I error rates than the percentile bootstrap, and coverage, interval width, and imbalance comparable to normal theory, percentile bootstrap, and the bias-corrected bootstrap confidence limits. Study 2 evaluated if a Bayesian method with true parameter values as prior information outperforms the other methods. The findings indicate that with true values of parameters as the prior information, Bayesian credibility intervals with informative prior distributions have more power, less imbalance, and narrower intervals than Bayesian credibility intervals with diffuse prior distributions, normal theory, percentile bootstrap, and bias-corrected bootstrap confidence limits. Study 3 examined how much power increases when increasing the precision of the prior distribution by a factor of ten for either the action or the conceptual path in mediation analysis. Power generally increases with increases in precision but there are many sample size and parameter value combinations where precision increases by a factor of 10 do not lead to substantial increases in power. / Dissertation/Thesis / Masters Thesis Psychology 2014
59

A Pilot Study to Examine the Feasibility of Measuring the QT Interval at Community Health Fairs

Gallo, Tyler, Beck, Joseph, Clark, Daniel, Malone, Daniel January 2016 (has links)
Class of 2016 Abstract / Objectives: This study assessed the feasibility of using a hand-held single lead ECG device to collect readable electrocardiograms (ECGs) in a community setting among the general population. Next, the goal was to determine if QT intervals could be measured from the collected ECGs. Additionally, this study was designed to examine if patients who had a prolonged QT interval were taking medications that are associated with an increased risk of prolonged QT interval. Methods: This prospective pilot study involved collecting ECGs via an AliveCor hand-held device at community health fairs. ECGs were evaluated for usefulness and QT intervals were measured if possible. Results: Forty-eight subjects participated in this pilot study. Forty-five viable ECGs were recorded using the hand-held device. Of the 45 ECGs, 38 were of sufficient quality to measure the QT interval and calculate QTc interval. There were no prolonged QT intervals observed in this study. Conclusions: The hand-held device recorded sufficient information to extract QT intervals for the majority of subjects. Due to the lack of prolonged QTc intervals, there was insufficient data to determine if this device could be utilized in the detection of QT prolongation due to medication use.
60

Evaluation of Large Dose, Extended Interval Aminoglycoside Dosing Protocols Using Pharmacokinetic Data from 515 Patients

Vu, Peter January 2011 (has links)
Class of 2011 Abstract / OBJECTIVES: The purpose of this study is to assess three published aminoglycoside dosing protocols (large-dose extended interval), to predict peak and trough concentrations of these protocols and to determine the percentage of patients with peak and trough concentrations within each protocol’s specified ranges. METHODS: This study is a retrospective analysis of clinical data. A database of 515 patients is used to analyze the three different protocols. The variables in this database encompass patients’ age, height, actual body weight (ABW), sex, k, Vd, and dose. From these data, patients' peak and trough concentrations were determined using the three large large, extended interval dosing protocols. RESULTS The results showed Nicolau protocol with the most potential of the three protocols. It had the highest percentages of patients with peak above 15 mg/L and a trough less than 0.5 mg/L. It also had the highest average peak of 19.1 mg/L with 69.9% of patients meeting the protocol’s specified peak range of 13 to 23 mg/L. CONCLUSION: The three examined protocols all showed a percentage of patients within the desired range. Of the three, Nicolau protocol I showed promising results with highest average peak, lowest average trough and high percentage of patients with concentrations within desired ranges. Its percentages above 15 mg/L and less than 0.5 mg/L are greater than protocols II and III. Nicolau dosing protocol may be best in achieving high peak and low trough concentrations.

Page generated in 0.0363 seconds