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

Probabilistic models to assist maintenance of multiple instruments

The paper discusses maintenance challenges of organisations with a huge number of devices and proposes the use of probabilistic models to assist monitoring and maintenance planning. The proposal assumes connectivity of instruments to report relevant features for monitoring. Also, the existence of enough historical registers with diagnosed breakdowns is required to make probabilistic models reliable and useful for predictive maintenance strategies based on them. Regular Markov models based on estimated failure and repair rates are proposed to calculate the availability of the instruments and Dynamic Bayesian Networks are proposed to model cause-effect relationships to trigger predictive maintenance services based on the influence between observed features and previously documented diagnostics

The Interpretation and Revocation of Unilateral Acts in the Strict Sense

It is with increasing frequency that States undertake unilateral acts. For that reason this article undertakes to demonstrate the development of unilateral acts of States in the heart of the International Law Commission of the United Nations - ILC. It analyzes unilateral and autonomous acts which can by themselves have juridical effects. In this sense, silence acquiescence and acceptance may have an influence in these acts.The ILC has studied this issue for ten years, analyzing its interpretation, the specific rules which are applicable, their modification, termination and the revocation of unilateral acts.

The verbal reasoning test workbook : umbeatable practice for verbal ability, English usage and interpretation and judgement tests.

Cada vez se utilizan mas las pruebas psicométricas, como parte del procedimiento de selección laboral. Casi todas las baterías de pruebas psicométricas incluyen un subtest de razonamiento verbal o una serie de preguntas. Este manual está pensado para quienes se enfrentan a una prueba de razonamiento verbal en el nivel intermedio y que carecen de cualquier práctica o confianza en sus destrezas. Ayuda a preparar estas pruebas con setecientas preguntas prácticas, una prueba de larga duración de simulación de práctica real, una explicación detallada de las respuestas y la interpretación de los resultados.

Close reading 11-14 : comprehension, interpretation and language activities.

Este recurso se compone de quince fragmentos, en su mayoría de novelas modernas, diseñados para alumnos de doce a catorce años. Los pasajes están, más o menos, clasificados en orden de dificultad, con las últimas selecciones procedentes de libros dirigidos a lectores adultos. Se ofrece un resumen para estimular el interés del conjunto del texto. Cada capítulo se centra en una característica específica del lenguaje y proporciona explicaciones y ejercicios de prácticas en ese aspecto. Los temas varían en dificultad, y los maestros pueden usar su criterio para decidir si una sección es apropiada para un grupo de alumnos en particular. Se proporciona al final del libro material para la revisión.

Interpretation, emotional reactions and daily life implications of hallucination-like experiences in clinical and nonclinical populations

Resumen tomado de la publicaci??n

Interpretation of the p value : A national survey study in academic psychologists from Spain

Resumen tomado de la publicaci??n

Re-interpretation of early speech perception test (standard version) in Urdu language

This paper resulted in the Urdu language version of the Early Speech Perception Test(ESP).

A new Rossby Wave-breaking interpretation of the North Atlantic Oscillation

This paper proposes the hypothesis that the low-frequency variability of the North Atlantic Oscillation (NAO) arises as a result of variations in the occurrence of upper-level Rossby wave–breaking events over the North Atlantic. These events lead to synoptic situations similar to midlatitude blocking that are referred to as high-latitude blocking episodes. A positive NAO is envisaged as being a description of periods in which these episodes are infrequent and can be considered as a basic, unblocked situation. A negative NAO is a description of periods in which episodes occur frequently. A similar, but weaker, relationship exists between wave breaking over the Pacific and the west Pacific pattern. Evidence is given to support this hypothesis by using a two-dimensional potential-vorticity-based index to identify wave breaking at various latitudes. This is applied to Northern Hemisphere winter data from the 40-yr ECMWF Re-Analysis (ERA-40), and the events identified are then related to the NAO. Certain dynamical precursors are identified that appear to increase the likelihood of wave breaking. These suggest mechanisms by which variability in the tropical Pacific, and in the stratosphere, could affect the NAO.

An interpretation of baroclinic initial value problems: results for simple basic states with nonzero interior PV gradients

In the Eady model, where the meridional potential vorticity (PV) gradient is zero, perturbation energy growth can be partitioned cleanly into three mechanisms: (i) shear instability, (ii) resonance, and (iii) the Orr mechanism. Shear instability involves two-way interaction between Rossby edge waves on the ground and lid, resonance occurs as interior PV anomalies excite the edge waves, and the Orr mechanism involves only interior PV anomalies. These mechanisms have distinct implications for the structural and temporal linear evolution of perturbations. Here, a new framework is developed in which the same mechanisms can be distinguished for growth on basic states with nonzero interior PV gradients. It is further shown that the evolution from quite general initial conditions can be accurately described (peak error in perturbation total energy typically less than 10%) by a reduced system that involves only three Rossby wave components. Two of these are counterpropagating Rossby waves—that is, generalizations of the Rossby edge waves when the interior PV gradient is nonzero—whereas the other component depends on the structure of the initial condition and its PV is advected passively with the shear flow. In the cases considered, the three-component model outperforms approximate solutions based on truncating a modal or singular vector basis.