Vicente Pastoriza

Combining meteorological radar and network of rain gauges data for space–time model development

SUMMARY Technological developments and the trend to go higher and higher in frequency give rise to the need for true space–time rain field models for testing the dynamics of fade countermeasures. There are many models that capture the spatial correlation of rain fields. Worth mentioning are those models based on cell ensembles. However, the rain rate fields created in this way need the introduction of the time variable to reproduce their dynamics. In this paper, we have concentrated on addressing the time domain effects while we have relied on existing spatial rain field models for creating initial fields, which are propagated (advected) according to proposed models and assumptions, some of which have been drawn from a combined use of a concurrent weather radar and a network of rain gauges. The dynamic modeling presented simulates the advection of a synthetically generated rain field according to dynamic, spatially correlated advection fields extracted from the analysis of weather radar images. Experimental data and model fits have been presented as well. Further ideas on how to improve the realism of the generated dynamic fields have also been presented. Furthermore, the limitations of radar data, especially those related to their limited time resolution, for the required space–time models have been pointed out. These can be overcome by using data from a network of rain gauges. However, it is important to be aware of the similarities and differences between these two sources. A comparative study of these two data sets has also been presented. Copyright r 2009 John Wiley & Sons, Ltd.

Nowcasting of the Spatiotemporal Rain Field Evolution for Radio Propagation Studies

This paper presents a nowcasting method capable of short-term forecasting the spatiotemporal rain field evolution, based exclusively on the analysis of radar reflectivity data without any a priori assumption on its spatial structure. The method has been developed to be integrated into future foreseen propagation impairment mitigation techniques, which take advantage of the temporal and spatial variability of rain in order to improve significantly the capacity and performance of the next-generation radiocommunication networks, operating at frequencies above 10 GHz . The rain field database used for assessing the nowcasting method consisted of 746 radar images collected by the weather radar located at A Coruña (Northwest Spain) during 25 rain events. The proposed method is made up of three main parts: a procedure that estimates the rain field displacement between two consecutive weather radar images, an algorithm that makes predictions for the next rain field displacement, and an operation that shifts the rain field according to the forecast displacement. The forecast quality of the developed method has been assessed by means of six skill indices common in the literature. Results reveal that the nowcasting method achieves a reasonably good forecast skill.

On the spatial structure of rainfall rate: Merging radar and rain gauge data

This paper extends some first steps given in merging radar and rain gauge data for a better understanding of rainfall rate spatial structure. The study has been performed analyzing spatial correlation between sites within a densely meshed rain gauge network and also with their corresponding pixels in weather radar images.

Cellular automata for predicting three-state rain rate and rain attenuation field dynamics

A straightforward linkage between rain cell dynamics in terms of reflectivity Z (dBz) or its equivalent rain rate R (mm/h) and satellite or terrestrial radiolink attenuation can be performed. This work focuses on the presentation of an approach for assessing and characterizing rain cell dynamics based exclusively on the analysis of the radar reflectivity scans recorded in weather radar image, and without an a priori assumption on the structure of rain cells. This research has been addressed by using cellular automata. Rain cell dynamics are simulated by using probabilistic cellular automata rules and tracking vectors which indicate a global advection direction and velocity.

Sistema Borroso de Inspección del Rebarnizado de Tapas en la Industria Metalgráfica

Se ha desarrollado un sistema de inspeccion automatico y en linea, basado en ingenieria de vision, para mejorar el control de calidad del rebarnizado de tapas abrefacil de envases metalicos en la industria metalgrafica y conservera. El algoritmo empleado por el sistema de ingenieria de vision estima la calidad media de rebarnizado de cada tapa mediante un sistema borroso. En este trabajo se presenta dicho algoritmo asi como la construccion del sistema borroso mediante un modelado neuro-borroso. El sistema de inspeccion examina el total de la produccion, clasifica las tapas de acuerdo con un inspector humano experto, ofrece interpretabilidad a los operarios del proceso para averiguar los motivos de fallo y reducir el tiempo medio entre fallos, y permite modificar la calidad minima de aceptacion de tapas. El algoritmo permite la inspeccion del total de la produccion de tapas y puede ser extendido a otros formatos de tapas.

Radar Rain Cell Identification and Modeling in the North-West of Spain

This study aims to characterize and model the rain fields in the North-West of Spain from Weather Radar Images. The study includes the modeling of these images according to two well known rain cell models: EXCELL and HYCELL. For this analysis, a procedure to detect rain fields and an algorithm for identifying rain cells within the images is presented. This work is part of an on-going activity trying to develop dynamic space-time models for rain fields for simulating rain induced effects on millimeter wave communication systems.

An experimental measuring instrument to characterize partial discharges by sensor fusion

The goal of this research work was the design and implementation of a measurement system that will be used for the partial discharge (PD) characterization in order to assess the condition of paper-oil (PO) insulation systems. In addition, the developed measuring instrument can be used to achieve a deeper understanding of the PD phenomena and their basis. This instrument integrates PD signals simultaneously measured using electric and ultrasonic sensors for making PD detection easier. The post-processing of the data captured from theses sensors allows a PD characterization based on the identification of the PD root cause and the localization of its source site. The performance of the proposed instrument was evaluated by sessions of controlled PD tests in the laboratory.

Electrical and ultrasonic measurement system for nondestructive testing

The goal of this research work was the design and implementation of a measurement system that will be used for the partial discharge (PD) characterization in order to assess the condition of paper-oil (PO) insulation systems. In addition, this measuring instrument can be used to achieve a deeper understanding of the PD phenomena and their basis. This instrument integrates PD signals simultaneously measured using electric and ultrasonic sensors for making PD detection easier. The post-processing of the data captured from theses sensors allows a PD characterization based on the identification of the PD root cause and the localization of its source site. The performance of the proposed instrument was evaluated by sessions of controlled PD tests in the laboratory.

Instrumentation system for industrial transformers

The Condition Monitoring of On-Load Tap Changers is very important because they have proved to be the elements with noticeable failures in a power transformer. This article describes the development of a portable virtual instrument for monitoring this kind of elements. The monitoring task is based in the measurement and analysis of the vibrations that a tap change produces. In contrast with other methods that can be used, this one has the advantage of being able to do continuous monitoring because the transformer can be operated on line.

Extracción de Características en Equipos Eléctricos basada en Medida de Vibraciones

A portable system for the condition monitoring of on-load tap changer in on-line power transformers by non-invasive inspections was developed. The system was based on a virtual instrument for measuring signals of voltage, current and vibration that a tap change produces. The the diagnosis of the functioning condition was done using vibration analysis. Inspections on transformers of several substations were done to test the proposed portable system. From the results, it is concluded that the virtual instrument facilitates this kind of inspection. Besides, a study carried out on a sole on-load tap changer did not discard the possibility of estimating the operating condition of on-load tap changers from the measured vibration signals. However, in order to guarantee this it will be necessary to performed more tests.