Nonparametric procedures use weak assumptions such as continuity of the distribution so that they are applicable to a large class F of underlying distributions. Statistics that are distribution-free over F may be constructed to be estimators of location. Such estimators are derived from rank tests called R-estimators. They are robust estimators. The concept of robust estimation is based on a neighborhood of parametric models called "gross error models". The M-estimator, which is a maximum likelihood type estimator, arose from such investigations using the normal distribution. A third big class of estimators is the class of linear combinations of order statistics called L-estimators. They are constructed as an average of quantiles. Examples are the sample mean and the sample median.In this thesis, some definitions and results involving these three basic classes of estimates are provided. For each class, an example of a robust estimator is presented. Numerical values are given to assess the robustness of each estimator in terms of breakdown point and gross error sensitivity. Further, the U-statistics which are unbiased estimators of location parameters, are used to obtain asymptotically efficient R-estimates. / Department of Mathematical Sciences

Over the last decade, considerable effort has been devoted to the implementation and analysis of self-tuning controllers on systems which are assumed to be represented exactly by linear dynamical models. In this thesis we examine the robustness of the self-tuning controller, when applied to systems consisting of a nominal linear plant which may have linear or nonlinear perturbations. Robust stability is the primary criterion and most of the results are for the Clarke-Gawthrop version of the self-tuning controller. Conditions are derived for the robust stability of the adaptively controlled system in terms of the design choices available to the engineer setting up the self-tuning controller. These are strong stability results in that they are in terms of both 1₂ and 1_∞ stability. The results are shown to be applicable to the general delay case and in the presence of non-zero mean disturbances. Preliminary results are also obtained for the robust stability of the explicit self-tuning controller.

Denna uppsats presenterar en undersökning av Vårdförbundets medlemmars inställning till nätjournal. Syftet med denna uppsats är att undersöka relationen mellan medlemmarnas inställning till nätjournal som reform och hur medlemmarna tror att nätjournal kommer påverka patienten samt deras eget arbete. En modell, som tagits fram genom explorativ och konfirmativ faktoranalys, presenterar relationen mellan medlemmarnas inställning till nätjournal som reform och hur medlemmarna tror att nätjournal kommer påverka patienten samt deras eget arbete i en strukturell ekvationsmodell. Undersökningen presenterar relationen utifrån medlemmarnas länstillhörighet. Länen är grupperade efter andel som ställer sig negativa till nätjournal som reform och fyra grupperingar kan urskiljas i en klusteranalys. Resultatet från undersökningen visar att det finns ett samband mellan inställning till nätjournal som reform och hur medlemmarna tror att nätjournal kommer påverka patienten samt deras eget arbete. Starkast relation till inställning till nätjournal som reform, i samtliga grupper, har frågor som berör patienten och hur denna påverkas av nätjournal. Skillnaderna mellan länsgrupperingarna kan urskiljas i fem enskilda frågor; ”Ditt sätt att skriva i journalen förändras av Journal på nätet?”, ”Patienter tar skada av den information de får via sin journalåtkomst?”, ”Obehöriga kommer att kunna ta del av patientuppgifter genom Journal på nätet?”, ”Journal på nätet ger en mer informerad patient?” och ”Patienters följsamhet till behandling ökar med tillgången till Journal på nätet?”.

Many minimum distance estimators have the potential to provide parameter estimates which are both robust and efficient and yet, despite these highly desirable theoretical properties, they are rarely used in practice. This is because the performance of these estimators is rarely guaranteed per se but obtained by placing a suitable value on some tuning parameter. Hence there is a risk involved in implementing these methods because if the value chosen for the tuning parameter is inappropriate for the data to which the method is applied, the resulting estimators may not have the desired theoretical properties and could even perform less well than one of the simpler, more widely used alternatives. There are currently no data-based methods available for deciding what value one should place on these tuning parameters hence the primary aim of this research is to develop an objective way of selecting values for the tuning parameters in minimum distance estimators so that the full potential of these estimators might be realised. This new method was initially developed to optimise the performance of the density power divergence estimator, which was proposed by Basu, Harris, Hjort and Jones [3]. The results were very promising so the method was then applied to two other minimum distance estimators and the results compared.

Robust object tracking plays a central role in many applications of image processing, computer vision and automatic control. In this thesis, robust object tracking under complex environments, including heavy clutters in the background, low resolution of the image sequences and non-stationary camera, has been studied. The interest of this study stems from the improvement of the performance of visual tracking using particle filtering. A Geometric Active contour-based Tracking Estimator, namely GATE, has been developed in order to tackle the problems in robust object tracking where the existence of multiple features or good object detection is not guaranteed. GATE combines particle filtering and the level set-based active contour method. The particle filtering method is able to deal with nonlinear and non-Gaussian recursive estimation problems, and the level set-based active contour method is capable of classifying state space of particle filtering under the methodology of one class classification. By integrating this classifier into the particle filtering, geometric information introduced by the shape prior and pose invariance of the tracked object in the level set-based active contour method can be utilised to prevent the particles corresponding to outlier measurements from being heavily reweighted. Hence, this procedure reshapes and refines the posterior distribution of the particle filtering. To verify the performance of GATE, the performance of the standard particle filter is compared with that of GATE. Since video sequences in different applications are usually captured by diverse devices, GATE and the standard particle filters with the identical initialisation are studied on image sequences captured by the handhold, stationary and PTZ camera, respectively. According to experimental results, even though a simple color observation model based on the Hue-Saturation-Value (HSV) color histogram is adopted, the newly developed. GATE significantly improves the performance of the particle filtering for object tracking in complex environments. Meanwhile, GATE initialises a novel approach to tackle the impoverishment problem for recursive Bayesian estimation using sampling method.

Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1992. / Vita. Abstract. Includes bibliographical references (leaves 164-168). Also available via the Internet.

Thesis (M. Phil.)--University of Hong Kong, 2007. / Title proper from title frame. Also available in printed format.

Thesis (Ph.D)--Aerospace Engineering, Georgia Institute of Technology, 2009. / Committee Chair: Mavris, Dimitri; Committee Member: Bishop, Carlee; Committee Member: Brown, David; Committee Member: Costello, Mark; Committee Member: Schrage, Daniel. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2009. / Committee Chair: Janet K. Allen; Committee Member: Benjamin Klein; Committee Member: Farrokh Mistree; Committee Member: Seung-Kyum Choi.

Thesis (M.S.)--Brigham Young University. Dept. of Mechanical Engineering, 2008. / Includes bibliographical references (p. 57-59).