Probabilistic sonar scan matching for an AUV

This paper proposes MSISpIC, a probabilistic sonar scan matching algorithm for the localization of an autonomous underwater vehicle (AUV). The technique uses range scans gathered with a Mechanical Scanning Imaging Sonar (MSIS), the robot displacement estimated through dead-reckoning using a Doppler velocity log (DVL) and a motion reference unit (MRU). The proposed method is an extension of the pIC algorithm. An extended Kalman filter (EKF) is used to estimate the robot-path during the scan in order to reference all the range and bearing measurements as well as their uncertainty to a scan fixed frame before registering. The major contribution consists of experimentally proving that probabilistic sonar scan matching techniques have the potential to improve the DVL-based navigation. The algorithm has been tested on an AUV guided along a 600 m path within an abandoned marina underwater environment with satisfactory results

Pose-based SLAM with probabilistic scan matching algorithm using a mechanical scanned imaging sonar

This paper proposes a pose-based algorithm to solve the full SLAM problem for an autonomous underwater vehicle (AUV), navigating in an unknown and possibly unstructured environment. The technique incorporate probabilistic scan matching with range scans gathered from a mechanical scanning imaging sonar (MSIS) and the robot dead-reckoning displacements estimated from a Doppler velocity log (DVL) and a motion reference unit (MRU). The proposed method utilizes two extended Kalman filters (EKF). The first, estimates the local path travelled by the robot while grabbing the scan as well as its uncertainty and provides position estimates for correcting the distortions that the vehicle motion produces in the acoustic images. The second is an augment state EKF that estimates and keeps the registered scans poses. The raw data from the sensors are processed and fused in-line. No priory structural information or initial pose are considered. The algorithm has been tested on an AUV guided along a 600 m path within a marina environment, showing the viability of the proposed approach

Analysis and regeneration of hypermedia contents through Java and XML tools

This paper presents a tool for the analysis and regeneration of Web contents, implemented through XML and Java. At the moment, the Web content delivery from server to clients is carried out without taking into account clients' characteristics. Heterogeneous and diverse characteristics, such as user's preferences, different capacities of the client's devices, different types of access, state of the network and current load on the server, directly affect the behavior of Web services. On the other hand, the growing use of multimedia objects in the design of Web contents is made without taking into account this diversity and heterogeneity. It affects, even more, the appropriate content delivery. Thus, the objective of the presented tool is the treatment of Web pages taking into account the mentioned heterogeneity and adapting contents in order to improve the performance on the Web

COMP3016 Web Technology - Strand "XML" Lecture 1

Lecture 1: Basic XML & HTML5 Lecture slides and exercises for reading and writing basic XML (without DTDs).

COMP3016 Web Technology - Strand "XML" Lecture 2

Lecture 1: DTDs and XML Structure Verification Lecture slides and exercises for validating XML with DTDs.

COMP3016 Web Technology - Strand "XML" Lecture 3

Lecture 3: DOM and XPath Lecture slides and exercises for using DOM and XPath to access material within an XML database or document.

COMP3016 Web Technology - Strand "XML" Lecture 5

Lecture 5: XLink and XPointer Lecture slides and exercises for using XLink and XPointer to link to and control material within an XML database or document.

COMP3016 Web Technology - Strand "XML" Lecture 6

Lecture 6: RDF and Metadata Lecture slides and exercises for using RDF to describe Web resources

XML revision

Discussions around the kind of decisions that people should make in their exam questions

Basic HTML & XML

Lecture 1: Basic XML & HTML5 Lecture slides and exercises for reading and writing basic XML and HTML

On the exhaustiveness of truncation and dropping strategies in many-to-many matching markets

We consider two–sided many–to–many matching markets in which each worker may work for multiple firms and each firm may hire multiple workers. We study individual and group manipulations in centralized markets that employ (pairwise) stable mechanisms and that require participants to submit rank order lists of agents on the other side of the market. We are interested in simple preference manipulations that have been reported and studied in empirical and theoretical work: truncation strategies, which are the lists obtained by removing a tail of least preferred partners from a preference list, and the more general dropping strategies, which are the lists obtained by only removing partners from a preference list (i.e., no reshuffling). We study when truncation / dropping strategies are exhaustive for a group of agents on the same side of the market, i.e., when each match resulting from preference manipulations can be replicated or improved upon by some truncation / dropping strategies. We prove that for each stable mechanism, truncation strategies are exhaustive for each agent with quota 1 (Theorem 1). We show that this result cannot be extended neither to group manipulations (even when all quotas equal 1 – Example 1), nor to individual manipulations when the agent’s quota is larger than 1 (even when all other agents’ quotas equal 1 – Example 2). Finally, we prove that for each stable mechanism, dropping strategies are exhaustive for each group of agents on the same side of the market (Theorem 2), i.e., independently of the quotas.

Interacciones de género estudiante-profesor, deserción y rendimiento académico en Colombia

En este trabajo se estima el efecto del género del profesor sobre la deserción y el rendimiento educativo de los estudiantes en Colombia durante el periodo 2009-2012. La estrategia empírica se fundamenta en un modelo de regresión lineal que establece la relación entre la proporción de profesoras interactuada con el género del estudiante. Los resultados sugieren que existe un sesgo de selección debido a que las profesoras aumentan la probabilidad de que las niñas finalicen la educación media, lo que implica que la composición de habilidades entre hombres y mujeres no es la misma. Luego de corregir este sesgo de selección, se encuentra un resultado significativo en el género del profesor. Un aumento de una desviación estándar en la proporción de profesoras incrementa en 0.01 desviaciones estándar el puntaje de los niños en la prueba de matemáticas y el puntaje de las niñas en la prueba de lenguaje. Este trabajo utiliza información proveniente de la prueba Saber 11, la Resolución 166 y el concurso docente.

Análisis del constructo reflexividad-impulsividad : del Matching Familiar Figures Test (MFFT) al MFFT20.

Resumen tomado de la revista