On the Radius of Convergence of Interconnected Analytic Nonlinear Systems

A complete analysis is presented of the radii of convergence of the parallel, product, cascade and unity feedback interconnections of analytic nonlinear input-output systems represented as Fliess operators. Such operators are described by convergent functional series, indexed by words over a noncommutative alphabet. Their generating series are therefore specified in terms of noncommutative formal power series. Given growth conditions on the coefficients of the generating series for the component systems, the radius of convergence of each interconnected system is computed assuming the component systems are either all locally convergent or all globally convergent. In the process of deriving the radius of convergence for the unity feedback connection, it is shown definitively that local convergence is preserved under unity feedback. This had been an open question in the literature

On the Radius of Convergence of Interconnected Analytic Nonlinear Input-Output Systems

A complete analysis is presented of the radii of convergence of the parallel, product, cascade and feedback interconnections of analytic nonlinear input-output systems represented as Fliess operators. Such operators are described by convergent functional series, which are indexed by words over a noncommutative alphabet. Their generating series are therefore specified in terms of noncommutative formal power series. Given growth conditions for the coefficients of the generating series for the subsystems, the radius of convergence of each interconnected system is computed assuming the subsystems are either all locally convergent or all globally convergent. In the process of deriving the radius of convergence for the feedback connection, it is shown definitively that local convergence is preserved under feedback. This had been an open problem in the literature until recently

Automated Detection of Lung Tuberculosis Based on X-ray Image Analysis

Detection of lung tuberculosis is mostly based on X-ray images. Image segmentation is important in different fields of image processing. Image segmentation is process of dividing images according to its characteristics. Different methods are presented for image segmentation. In this paper to find nodules, symptoms of diseases in X-ray images, we use watershed segmentation approach. First take the gray scale image and then applying the watershed segmentation approach to segment the image with catchment basins. When the lung image is isolated from X-ray image, the suspected nodule pixels in the lung can be found. Based on nodules and user’s input symptoms, patient can be defined either suffer from lung TB or not

A robust but easily implementable remote control for quadrotors: Experimental acrobatic flight tests

International audienceExperimental flight tests are reported about quadrotors UAVs via a recent model-free control (MFC) strategy , which is easily implementable. We show that it is possible to achieve acrobatic rate control of the UAV, which is beyond the previous standard. The same remote controller is tested on two physical vehicles without any re-tuning. It produces in both cases low tracking error. We show that MFC is robust even when the quadrotor is highly damaged. A video footage can be found at: https://youtu.be/wtSLalA4sz

Understanding Child Prostitution in Thailand in the 1990s

Child prostitution in Thailand became visible in the 1990s. Fueled by accounts by media and nongovernmental organizations, the problem was cast as a straightforward moral issue of coercive parents, helpless child victims, and evil perpetrators. Legal interventions that prosecuted parents and clients were put in place to solve the problem. However, these policies failed to consider ethnographic research on how children and families understood prostitution, and the role it played in their kinship systems and moral economies. In this article, I look at how the problem has been conceptualized. I argue that without a fuller understanding of family relationships and the reciprocal obligations between children and parents, and without listening to children themselves, interventions to protect children were bound to fail