Hierarchical approach to enhancing topology-based WiFi indoor localization in large environments

Traditionally, WiFi has been used for indoors localization purposes due to its important advantages. There are WiFi access points in most buildings and measuring WiFi signal is free of charge even for private WiFi networks. Unfortunately, it also has some disadvantages: when extending WiFi-based localization systems to large environments their accuracy decreases. This has been previously solved by manually dividing the environment into zones. In this paper, an automatic partition of the environment is proposed to increase the localization accuracy in large environments. To do so, a hierarchical partition of the environment is performed using K-Means and the Calinski-Harabasz Index. Then, different classification techniques have been compared to achieve high localization rates. The new approach is tested in a real environment with more than 200 access points and 133 topological positions, obtaining an overall increase in the accuracy of approximately 10% and reducing the error to the real position to 2.45 metres.Ministerio de Ciencia e InnovaciónUniversidad de AlcaláPrincipado de Asturia

Fuzzy classifier ensembles for hierarchical WiFi-based semantic indoor localization

The number of applications for smartphones and tablets is growing exponentially in the last years. Many of these applications are supported by the so-called Location Based Services, which are expected to provide reliable real-time localization anytime and anywhere, no matter either outdoors or indoors. Even though outdoors world-wide localization has been successfully developed through the well-known Global Navigation Satellite System technology, its counterpart large-scale deployment indoors is not available yet. In previous work, we have already introduced a novel technology for indoor localization supported by a WiFi fingerprint approach. In this paper, we describe how to enhance such approach through the combination of hierarchical localization and fuzzy classifier ensembles. It has been tested and validated at the University of Edinburgh, yielding promising results.Ministerio de Economía y CompetitividadXunta de Galici

Tratamiento de la esquizofrenia en el primer episodio psicótico. Revisión de la literatura

La esquizofrenia es un trastorno mental psicótico, de etiología en estudio, caracterizado por alteraciones del pensamiento, del estado de ánimo y del comportamiento. Objetivo: Analizar la literatura del 2006 al 2011 acerca del manejo del primer episodio psicótico en la esquizofrenia. Material y método: Revisión sistemática de la literatura de acuerdo con criterios de la Medicina Basada en Evidencias de acuerdo con el Centre for Evidence-Based Medicine (CEBM) de Oxford. Resultados: De un total de 50 artículos, 23 de ellos (46%) hacen referencia a aspectos farmacológicos y 27 artículos (54%) describen intervenciones psicosociales, terapia molecular y seguimiento de tratamientos farmacológicos por estudios de neuro-imagen. Un solo artículo correspondió a nivel de evidencia 1 y grado de recomendación A. Conclusiones: El manejo de la esquizofrenia está con antipsicóticos de segunda generación y la disminución del problema se ve al final del primer a˜no de manejo. La adición de antagonistas alfa 2 mejora la eficacia de los fármacos antipsicóticos al reducir los síntomas negativos. © 2014 Universidad Autónoma del Estado de México. Publicado por Masson Doyma México S.A. Todos los derechos reservado

A Comparison of SLAM Algorithms with Range Only Sensors

2014 IEEE International Conference on Robotics and Automation (ICRA),31 May 2014 - 07 June 2014, Hong-Kong, ChinaLocalization and mapping in indoor environments, such as airports and hospitals, are key tasks for almost every robotic platform. Some researchers suggest the use of RO (Range Only) sensors based on WiFi (Wireless Fidelity) technology with SLAM (Simultaneous Localization And Mapping) techniques. The current state of the art in RO SLAM is mainly focused on the filtering approach, while the study of smoothing approach with RO sensors is quite incomplete. This paper presents a comparison between a filtering algorithm, the EKF, and a smoothing algorithm, the SAM (Smoothing And Mapping). Experimental results are obtained, first in an outdoor environment using two types of RO sensors and then in an indoor environment with WiFi sensors. The results demonstrate the feasibility of the smoothing approach with WiFi sensors in indoors

Robust Traffic Sign Detection by means of Vision and V2I Communications

14th International IEEE Annual Conference on Intelligent Transportation Systems - ITSC, , 05/10/2011-07/10/2011, Washington DC, Estados UnidosThis paper presents a complete traffic sign recognition system, including the steps of detection, recognition and tracking. The Hough transform is used as detection method from the information extracted in contour images, while the proposed recognition system is based on Support Vector Machines (SVM), and is able to recognize up to one hundred of the main road signs. Besides a novel solution to the problem of discarding detected signs that do not pertain to the host road is proposed, for that purpose vehicle-to-infrastructure (V2I) communication and stereo information is used. This paper presents plenty of tests in real driving conditions, both day and night, in which a high success rate and low number of false negatives and true positives were obtained, and an average runtime of 35 ms, allowing real-time performance

Using the ℓ1-norm for Image-based tomographic reconstruction

This paper introduces an ℓ1-norm model based on Total Variation Minimization for tomographic reconstruction. The reconstructions produced by the proposed model are more accurate than those obtained with classical reconstruction models based on the ℓ2-norm. This model can be linearized and solved by linear programming techniques. Furthermore, the complementary slackness conditions can be exploited to reduce the dimension of the resulting formulation by removing unnecessary variables and constraints. Since the efficacy of the reduced formulation strongly depends on the quality of the dual-multipliers used when applying the reduction method, Lagrangian relaxation is used to obtain near-optimal multipliers. This allows solving larger instances in an efficient way

Vision-Based Traffic Data Collection Sensor for Automotive Applications

This paper presents a complete vision sensor onboard a moving vehicle which collects the traffic data in its local area in daytime conditions. The sensor comprises a rear looking and a forward looking camera. Thus, a representative description of the traffic conditions in the local area of the host vehicle can be computed. The proposed sensor detects the number of vehicles (traffic load), their relative positions and their relative velocities in a four-stage process: lane detection, candidates selection, vehicles classification and tracking. Absolute velocities (average road speed) and global positioning are obtained after combining the outputs provided by the vision sensor with the data supplied by the CAN Bus and a GPS sensor. The presented experiments are promising in terms of detection performance and accuracy in order to be validated for applications in the context of the automotive industry

Perception advances in outdoor vehicle detection for automatic cruise control

This paper describes a vehicle detection system based on support vector machine (SVM) and monocular vision. The final goal is to provide vehicle-to-vehicle time gap for automatic cruise control (ACC) applications in the framework of intelligent transportation systems (ITS). The challenge is to use a single camera as input, in order to achieve a low cost final system that meets the requirements needed to undertake serial production in automotive industry. The basic feature of the detected objects are first located in the image using vision and then combined with a SVMbased classifier. An intelligent learning approach is proposed in order to better deal with objects variability, illumination conditions, partial occlusions and rotations. A large database containing thousands of object examples extracted from real road scenes has been created for learning purposes. The classifier is trained using SVM in order to be able to classify vehicles, including trucks. In addition, the vehicle detection system described in this paper provides early detection of passing cars and assigns lane to target vehicles. In the paper, we present and discuss the results achieved up to date in real traffic conditions.Ministerio de Educación y Cienci

Diseño y desarrollo de un laboratorio virtual de aplicaciones industriales con láser

El objetivo de este trabajo es el diseño y desarrollo de un laboratorio virtual de aplicaciones industriales de los láseres de potencia. La posibilidad de utilizar modelos de simulación con una determinada gestión del conocimiento para facilitar la realización de experimentos prácticos en asignaturas relacionadas con las aplicaciones industriales del láser, así como para el adiestramiento del cuadro técnico de estos sistemas puede ser muy ventajoso con vistas a la reducción del tiempo, recursos y coste del entrenamiento. Si estos modelos son accesibles a través de internet la ventaja se multiplica, ya que esta característica flexibiliza el procedimiento de aprendizaje al eliminar las restricciones espacio-temporales del proceso de instrucción haciendo posible y facilitando su uso tanto en asignaturas de titulaciones oficiales de impartidas en la ETSII-UPM como en la colaboración en la formación técnica entre organizaciones punteras del área de la tecnología láser de diferentes países

Análisis de la Influencia de los Parámetros Operacionales en Recubrimientos Superficiales Asistidos por Láser de Acero AISI 431 sobre Acero al Carbono

En el presente artículo se muestran los resultados obtenidos de un estudio basado en una serie de recubrimientos de acero inoxidable martensítico AISI 431 sobre acero al carbono. El objetivo principal de este trabajo es valorar la influencia de los principales parámetros operacionales que intervienen en el proceso. This paper presents the main results of a study based on laser cladding of AISI 431 stainless steel powder on low carbon steel experiments. The objective of this work is to show the influence of the processing parameters in the clad