Non destructive evaluation of absorbing materials using microwave stimulated infrared thermography

The electromagnetic wave nondestructive evaluation methods that appeared some years ago are attractive because many materials can absorb hyperfrequency energy. Nevertheless, generally the detections are achieved point by point which is highly time consuming for NDE of extended structures. We developed a global method which associates electromagnetic stimulation and a detection by an IR camera (EMIR method). For others applications, this method has been used over the past several years [1,2]. The aim of this paper is to give the first results about the possibilities of this new method for NDE

Human rights, non-refoulement and the protection of refugees in Hong Kong

Although the 1951 Convention relating to the Status of Refugees and its 1967 Protocol do not apply to Hong Kong, asylum seekers have challenged Hong Kong's lack of an adequate refugee policy in a series of judicial review actions grounded in human rights and common law principles. This article focuses on two cases in particular in which the applicants have attempted to rely, in part, on a right to non-refoulement, derived from international and domestic law, to compel the Government to establish procedures to determine the status of refugees and other similar categories of claimants. The first, Secretary for Security v. Sakthevel Prabakar, led to the creation of a 'torture screening' mechanism based on article 3 of the Convention against Torture and other Cruel, Inhuman, or Degrading Treatment or Punishment. In the second, C v. Director of Immigration, the court considered whether a rule of non-refoulement has emerged in customary international law and, if so, whether it applies to Hong Kong and requires government-administered refugee status determination. Although the applicants failed at first instance,1 an analysis of the judgment with reference to Hong Kong's human rights obligations reveals gaps in the court's reasoning and demonstrates the potential for greater reliance on these standards as the basis for developing a more comprehensive protection framework. This examination of the Hong Kong experience may have broader comparative value, especially in the Asian region and in jurisdictions not bound by the Refugee Convention or its Protocol. © The Author (2010). Published by Oxford University Press. All rights reserved.postprin

Inspección mediante técnicas no destructivas de un edificio histórico: oratorio San Felipe Neri (Cádiz)

The main aim of this article is showing the results that have been obtained when non destructive techniques (ultrasound and thermography) are applied to a building with an important artistic and historical value. These non-destructive techniques have been applied in the inspection of the wooden roof structure to detect different states of deterioration, loss of density and defects. The aim is the assessment the state of the preservation of the wooden structure. A fieldwork has been carried out, where the two techniques have been applied together, ultrasound, an effective technique to establish the diagnosis of a wooden structure, and the thermography, a technique less tested in the in situ inspection of this material. The aim is checking the range and the real possibilities of using of each technique. In this sense, the methodology of ultrasound developed and published by the authors is applied and the thermography like in situ inspection tool, analysing additional difficulties and interference parameters not found in laboratory. The conclusions of this study show that the union of the ultrasound technique and the thermography is a good tool for on-site inspection of wooden structures and to assess their conditions allowing establishing a proper diagnosis. Thermography can detect different moisture contents and different materials and, on the other hand, ultrasound detects different states of deterioration or loss of density in specific areas with a high moisture content of the pieces.El objetivo de este artículo es dar a conocer los resultados obtenidos al aplicar técnicas no destructivas de inspección (ultrasonidos y termografía) durante las obras de reparación de un edificio de gran valor histórico y artístico. Estas técnicas no destructivas se han aplicado en la inspección de la cubierta de madera del edificio para detectar distintos estados de deterioro, pérdidas de densidad y defectos, con el objetivo de evaluar su estado de conservación. Se ha realizado un trabajo de campo donde se ha aplicado ambas técnicas conjuntamente, los ultrasonidos, técnica eficaz para establecer el diagnóstico de una estructura de madera, y la termografía, técnica menos experimentada en la inspección in situ de este material. El objetivo es acotar el alcance y las posibilidades reales de utilización de cada una de las técnicas. En este sentido, se aplica la metodología de ultrasonidos desarrollada y publicada por las autoras y se estudia la termografía como herramienta de inspección in situ analizando las dificultades añadidas y parámetros de interferencia no detectados en laboratorio. Las conclusiones del trabajo ponen de manifiesto que la unión de la técnica de ultrasonidos y la termografía constituyen una buena herramienta para la inspección in situ de las estructuras de madera y para evaluar sus condiciones permitiendo establecer un diagnóstico adecuado. La termografía permite detectar distintos contenidos de humedad y distintos materiales y, por otro lado, los ultrasonidos los distintos grados de deterioro o pérdida de densidad en zonas localizadas con elevado contenido de humedad de las piezas

A Critical Review on the Structural Health Monitoring Methods of the Composite Wind Turbine Blades

With increasing turbine size, monitoring of blades becomes increasingly im-portant, in order to prevent catastrophic damages and unnecessary mainte-nance, minimize the downtime and labor cost and improving the safety is-sues and reliability. The present work provides a review and classification of various structural health monitoring (SHM) methods as strain measurement utilizing optical fiber sensors and Fiber Bragg Gratings (FBG’s), active/ pas-sive acoustic emission method, vibration‒based method, thermal imaging method and ultrasonic methods, based on the recent investigations and prom-ising novel techniques. Since accuracy, comprehensiveness and cost-effectiveness are the fundamental parameters in selecting the SHM method, a systematically summarized investigation encompassing methods capabilities/ limitations and sensors types, is needed. Furthermore, the damages which are included in the present work are fiber breakage, matrix cracking, delamina-tion, fiber debonding, crack opening at leading/ trailing edge and ice accre-tion. Taking into account the types of the sensors relevant to different SHM methods, the advantages/ capabilities and disadvantages/ limitations of repre-sented methods are nominated and analyzed

Pathways to sustainability: a critical review of the sustainable development paradigm

Different methods of NDT of carbon-epoxy laminates have been used up till now, including ultrasonics, X-ray photography and vibrothermography. Thermal methods are now appearing, because they can be contactless and single ended [1–3]. Among these methods, pulsed back emission photothermal radiometry seems attractive because it is a simple method, where elasticity is uncoupled. So the possibility of quantitatively characterizing delaminations is offered, as the model describing the phenomenon is simple. Results recently obtained at the Office National d’Etudes et de Recherches Aérospatiales (ONERA) are presented here to demonstrate that the method is well suited to the detection, in-depth localization and characterization of delaminations in carbon-epoxy composites

The PTR 8900: An Industrial Apparatus for Testing Materials by Infrared Photothermography

Infrared thermography, as a NDT tool, has been used intensively by nondestructive evaluation engineers for the testing of composite and plastic materials. Some application, vibrothermography [1,2], requires the use of a mechanical shaker to induce localized heating in the material, while some other, stimulated photothermography, requires the application of an external light source to create time-varying thermal patterns in the material under test [3,4

Dimensioning and location planning for wireless networks under multi-level cooperative relaying

This paper studies the problem of network dimensioning and location planning in multi-hop wireless networks. A key technology of wireless multi-level cooperative relaying (CR) is incorporated, which has been recognized as an effective design paradigm for achieving throughput enhancement. A mathematical formulation is presented to capture the nature of the problem, and characterize the behavior of multi-level CR. The tasks of dimensioning, relay placement, relay allocation, and relay sequence design have been considered in a unified optimization framework. The formulation is a nonlinear integer program. To avoid the intractable computation complexity in solution, an efficient two-phase algorithm is developed. We conduct a series of case studies to verify the proposed algorithm, in which the results demonstrate the efficiency of our proposed algorithm and the significant benefits in terms of deployment cost reduction under multi-level CR. © IFIP International Federation for Information Processing 2009.link_to_subscribed_fulltex

Non destructive evaluation of absorbing materials using microwave stimulated infrared thermography

The electromagnetic wave nondestructive evaluation methods that appeared some years ago are attractive because many materials can absorb hyperfrequency energy. Nevertheless, generally the detections are achieved point by point which is highly time consuming for NDE of extended structures. We developed a global method which associates electromagnetic stimulation and a detection by an IR camera (EMIR method). For others applications, this method has been used over the past several years [1,2]. The aim of this paper is to give the first results about the possibilities of this new method for NDE.</p