Search results for "35"

Monitoring and prediction in early warning systems for rapid mass movements

2015

Rapid mass movements (RMM) pose a substantial risk to people and infrastructure. Reliable and cost-efficient measures have to be taken to reduce this risk. One of these measures includes establishing and advancing the state of practice in the application of early warning systems (EWSs). EWSs have been developed during the past decades and are rapidly increasing. In this paper, we focus on the technical part of EWSs, i.e., the prediction and timely recognition of imminent hazards, as well as on monitoring slopes at risk and released mass movements. Recent innovations in assessing spatial precipitation, monitoring and precursors of the triggering and deformation of RMM offer new opportunities…

Failure Rate Measurement on Silicon Diodes Reverse Polarized at High Temperature

2017

This paper calculates the failure rate on reversed polarized silicon diodes with the aim to justify, experimentally, the rules of the European Space Agency (ESA) which are referred to the component life’s extension, the reliability increase and the end of life performance enhancement, by using oversized devices (derating rules). In order to verify the derating rules, 80 silicon diodes are used, which are reverse polarized in a high temperature environment. The diodes are divided in 4 groups of 20 diodes, applying a different voltage to each group, in order to relate the failure rate to the applied derating rule. The experiment described in this paper is developed using a temperature acceler…

Benefits and Drawbacks of A High Frequency Gan Zvzcps Converter

2017

This paper presents the benefits and drawbacks of replacing the traditional Si Mosfets transistors with enhancement mode GaN transistors in a Half-Bridge Zero Voltage and Zero Current Switching Power Switching (ZVZCPS) converter. This type of converters is usually used as Electronic Power Converters (EPC) for telecommunication satellites travelling-wave tube amplifiers (TWTAs). In this study, firstly the converter is theoretically analysed, obtaining its operation, losses and efficiency equations. From these equations, optimizations maps based on the main system parameters are obtained. These optimization maps are the key to quantify the potential benefits of GaN transistors in this type of…

Prototyping and Characterization of 1.2KV SIC Schottky Diodes for TWTA Application: The Challenge to Meet the User Specification

2017

The intensity of rainfall in Mediterranean environments. Extreme values according to the scale of observation

2015

Mediterranean environments are dominated by episodes of torrential rain, whereby the critical parameter is not so much the amount of rain these episodes accumulate, but rather the intensity they can reach. The heavy intensities that extreme events can achieve are critical in the dynamics of soil erosion; those related to triggering of debris-flow and above all in hydrology, as they affect rainfall-runoff conversion processes, runoff and coefficient thresholds and flash floods generation.

Towards automatic calibration of 2-D flood propagation models

2010

Abstract. Hydraulic models for flood propagation description are an essential tool in many fields and are used, for example, for flood hazard and risk assessments, evaluation of flood control measures, etc. Nowadays there are many models of different complexity regarding the mathematical foundation and spatial dimensions available, and most of them are comparatively easy to operate due to sophisticated tools for model setup and control. However, the calibration of these models is still underdeveloped in contrast to other models like e.g. hydrological models or models used in ecosystem analysis. This has two primary reasons: first, lack of relevant data against which the models can be calibr…

Roots Characteristics of a flexible and mature vegetation: Preliminary results of experimental investigation in a meandering laboratory flume

2018

Vegetation controls sediment dynamics and affects the kinematic characteristics of flow in rivers. The uprooting mechanism is strongly affected by mechanical properties, morphology and branching of the roots system. This work presents preliminary results of experimental work conducted in a laboratory meandering flume. The work aims to investigate how the geometrical and mechanical characteristics of the roots of a real, flexible and mature vegetation could vary along the bend. Results show that both the geometrical and the mechanical characteristics of the roots assume higher/lower values in peculiar sections of the bend suggesting that they could be affected by the kinematic characteristic…

Output Impedance Improvement Using Coupled Inductors

2017

When using a single DC/DC converter with multiple outputs and having a buck topology, which has one filter inductor per output, the designer can choose to couple these outputs together. This paper demonstrates additional benefits of coupling output inductors together. Apart from saving mass and volume, and due to an improved small signal behaviour it also reduces the output impedance of the regulated output. The paper will analyse a seven output push-pull converter used as a space power converter module and verify the theoretical results with experimental measurements.

Erosión costera y cambio ambiental en el humeral de Cabanes-Torreblanca (Castelló). Datos para una gestión sostenible

2014

A progressive increase in salinity and marine influence, related to local subsidence characterize the evolution of the lagoon of Cabanes Torreblanca. Relative sea level rise, caused saltwater intrusion and landward migration of the barrier. This barrier is recessive (60-20 m in the last 50 years) and its current processes show a sedimentary deficit that can lead to rapid and irreversible changes. The information shown by this research can help to achieve a sustainable management.

La intensidad de lluvia en entornos mediterráneos. Valores extremos según la escala de observación

2015

Este trabajo estudia la estructura de las intensidades máximas de lluvia a diferentes escalas de observación, entre los 5 minutos y las 24 horas, en la Confederación Hidrográfica del Júcar, en base a datos del SAIH (1994-2007). Aborda además la influencia de los factores de altitud y distancia al mar, así como de la exposición del territorio: litoral-interior y compartimentación general del relieve. Los resultados muestran una gran dependencia de la intensidad en relación con la escala de observación, una influencia significativa de la distancia al mar y dos patrones de intensidad.