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The existence of some 100 million active mines threatens human life and curtails substantially the economic base in over 70 countries. Humanitarian demining is tedious and it currently only employs metal detectors, prodders, dogs and armoured mechanical vehicles.
Achieving a world free of mines within a period of 10 years as stipulated in international treaties requires safer and more efficient technologies. In response to this challenge the Working Group 5 of the European Federation for Non-Destructive Testing (EFNDT WG5) was founded in Berlin in March 1999. The subject of this working group now consisting of 50 members from 17 countries is the detection of antipersonnel mines (APMD). The basic idea was to investigate existing NDT methods into their ability to aid mine detection. The scope of activities ranged from collecting available information, setting up links to related organisation, defining terminology and standards to selecting dedicated research projects. Since some of these tasks are already conducted by other organisations on an European and international level the attention of the working group has been focused mainly on two R&D areas and on reliability assessment studies. Otherwise, EFNDT WG5 APMD nevertheless remains open to novel approaches in mine detection. Aim of all activities is to provide deminers with safer and more efficient tools than merely with prodders and metal detectors currently used for their dangerous task.
Zusammenfassung
Der Prototyp einer Flachröntgenröhre mit einer maximalen Röntgenenergie von 240kV (600W) und einer Brennfleckgröße von 0,4 * 0,4 mm nach DIN EN 12543 wird vorgestellt. Das Design dieser Flachröntgenröhre mit geringer Aufbauhöhe ist in Metall-Keramik-Technik ausgeführt. Die Beschleunigungsstrecke Katode-Anode ist senkrecht zur Haubenachse ausgeführt. Die Röhre ist als bipolares System aufgebaut. Kleine Durchmesser der Hochspannungskabel verringern das Gewicht und resultierende Kraftmomente bei der manuellen Manipulation sowie beim Verfahren in einem mechanisierten System. Der Targetwinkel beträgt 6° und bewirkt eine höhere Brillianz der Röntgenstrahlung. Die Geometrie des Strahlenaustrittsfensters (Emissionsfenster) ist in Fächerstrahlgeometrie zur tomografischen Prüfung ausgelegt.
Radiography is a helpful method to identify the inherent structure of unexploded ordnances (UXOs). Portable Computed Radiography (CR) systems on the basis of phosphor imaging plates , have attracted attention for NDT-applications during the last few years. A portable IP system ACR 2000 has been tested for X-ray inspection of UXO's in the field. Digitised radiographs are presented to explain the needs and demands for a reliable characterisation of UXO's. Computed radiographs of UXOs are compared with film radiographs exposed in the same way, to evaluate the reliability and to identify advantages and disadvantages of the CR system for UXO inspection. Film based and CR systems provide sufficient information for identification of chemical warfare agents in UXO's, which is an essential problem for explosive ordnance disposal. The advantages and the potential of the portable CR system is discussed on the basis of experiences gathered during different field trails.
Podiumsdiskussion - Pro und Contra: Filmersatz durch digitale Medien, Empfehlung für die Zukunft
(2002)
Annual Report of SCVA
(2003)
Bericht des Vorsitzenden
(2003)
The reliability investigations are dedicated to throw light on the performance of the NDE system with
respect to the required aim. This is especially of interest when digitized and processed signals are
involved where it becomes hard to assess whether the quality of the system has raised or not. Three
different ways to investigate reliability of NDE signals will be described. The first way of investigation,
the performance demonstration, is preferred e.g. in the US American nuclear power industry. This is an
integral consideration of the non destructive test as a system where the whole NDE system is packed in a
black box and only the input in terms of the real existing flaws in the component is considered and
compared to the output in terms of the indications of the human inspector or of the automated system.
The second the European tradition relies on a standardized description of physical/technical
parameters of the NDE system which are preconditions for successful system performance. An example
for such a standardized set of performance parameters is given in the recently released standard about Xray
film digitization CEN EN 14096. The third approach the modular conception is a marriage of
both: The signal chain is cut into main modules. Each module is assessed in a most appropriate
individual way e.g. via modeling calculations. The single results are joint together according to the
reliability of the subsystems. Separating criteria for the system were proposed through a reliability
formula developed during a series of European-American workshops on NDE reliability. Examples of
all three approaches will be given.
Das Basisanliegen - Einleitung
Mit der zunehmenden Zahl akkreditierter ZfP-Firmen und zunehmender Anwendung risikobasierender Konzepte ergibt sich die Notwendigkeit, internationale Standards wie die DIN EN ISO 17025 und darüber hinausgehende Richtlinien bei der Verfahrensauswahl in der ZfP zu berücksichtigen. Dieser Aufsatz soll aufzeigen, welche internationalen Aktivitäten gegenwärtig für die Zuverlässigkeitsbetrachtungen von Bedeutung sind (siehe auch [1]). In Übereinstimmung mit den Vereinbarungen und Definitionen der European-American Workshops zur Zuverlässigkeit [2, 3] gilt: Das Basisanliegen der Zuverlässigkeitsuntersuchungen beliebiger diagnostischer Systeme besteht darin, den Grad festzustellen mit dem das Prüfsystem in der Lage ist, seinen vorgesehenen Zweck zu erfüllen. Im Falle der ZfP besteht dieser Zweck zumeist in der Aufgabe, Bauteildefekte aufzufinden und zu beschreiben bzw. die Defektfreiheit von Bauteilen zu bestätigen, sowie Wanddicken zu messen oder Material zu charakterisieren.
Das Basisanliegen der Zuverlässigkeitsuntersuchungen findet seinen Niederschlag bei folgenden international relevanten Aktivitäten:
neue ISO 17025 als Notwendigkeit mit variablen Möglichkeiten der Verfahrensvalidierung
als Kettenglied in RBLM (Risk Based Life Time Management) (r) EPERC-Initiative
CEN/TC138/WG9 "Qualifizierung von ZfP-Verfahren"
Six-Sigma Strategie: als notwendiger Bestandteil
ASNT-Initiative: Standing Committee on NDE Reliability: als Arbeitspaket
Produkthaftung: als notwendige Voraussetzung für die Handhabung
During the second European-American Workshop on NDE Reliability, September 99 in Boulder, the term NDE reliability was defined as the degree that an NDT system is capable of achieving its purpose regarding detection, characterization and false calls. The most common but also most expensive - way to determine this degree of capability in e.g. defect detection is to make just a performance demonstration using realistic test samples and to count the correct detections and false calls. For a more efficient way of reliability evaluation we propose to decompose the system into main modules e.g. according to the reliability formula set up on the first workshop: into f(IC) a function of IC the intrinsic capability, determined by the physics and the technique of the NDE method representing an ideal upper bound of the reliability and g(AP) a function of AP the industrial application factor like surface state or limited access to a component in general diminishing the ideal capability and finally h(HF) the function of the human factor which is in general also diminishing the ideal capability. The workshop proposed a rather plain mathematical shape for the formula R = f(IC) g(AP) h(HF) which should be considered merely as a philosophical expression but not as exact mathematical formula to be applied for evaluation of e.g. POD data. We propose to decompose the NDE system into modules in terms of functions of IC, AP and HF if appropriate or additional ones if necessary and then to analyze the mutual relationships of the terms via fault tree analysis. Finally the total reliability of the system is composed of the reliability of the subsystems via the rules of statistical systems theory.
First trials for this approach of data analysis will be presented via examples from NDE systems in the aerospace industry.
Tomographical Computer Aided Radiology (TomoCAR) is based on the mechanical position control of
an X-ray tube in front of a welding seam and the application of a planar array detector behind it. Several hundred
radiometric projections in small angle steps are acquired. The tomographical reconstruction allows the three-dimensional
(3D) representation of the defects. A new radiometric array detector system with a small internal
unsharpness and high image contrast is used for the 2- and 3-dimensional visualization and sizing of planar defects
with a defect opening of less than 100 µm. This detector is based on a CMOS-flat panel with a direct converting
CdTe-single crystal layer. The small design allows the application of the mobile testing equipment for mechanized
X-ray inspection in industrial plants. The physical pixel size of the detector amounts to 0,1x0,1 mm². Nevertheless,
this system yields a better spatial resolution than indirect converting detectors (e.g. cameras with fluorescence
layers of Gd2O2S). It allows the reliable detection of planar defects with openings far below the detector pixel size
by subpixel resolution.
'TomoCAR' is qualified at present in the context with a German pilot study following to the ENIQ guidelines for
the employment within the nuclear power industry.
In diesem Beitrag wird die Anwendung von Radiographiesystemen zum Auffinden von Holzschäden beschrieben. Die Anlage besteht aus einer mobilen Röntgenblitzröhre und einem digitalen Radiographiesystem mit Speicherfolie oder einem Flachdetektor. An Hand der durchgeführten Versuche an Laub- und Nadelbäumen sowie an Eichenbalken der Marienkirche der Lutherstadt- Wittenberg wird die Detektion innerer Schäden gezeigt.
The quantitative measurement of kind, positions and diameters of steel reinforce ments in building constructions is a typical inspection problem in civil engineering. A classical solution is the combination of film radiography with the multi angle technique and graphical backprojection. New digital detectors reduce the exposure time and allow the application of stereo radiography and computed laminography as routine applications.
The computed laminography allows fast and effectively the determination of the depth of reinforcements in concrete or masonry. A selected area of the steel re-bar structure is penetrated by gamma-rays from different angles of incidence (multi angle-technique) with a Co-60-source. Instead of a radiographic film phosphor imaging plates were used as a new digital medium for filmless radiography. A 3D-image of the measured region of interest is reconstructed from the digitised projections of a test block. The reconstruction is based on special tomosynthesis algorithms which need few projections only.
Radiographic techniques were uses in completion to other techniques like radar, electromagnetic alternating field inspection to examine the structure of different buildings. Experiences of inspections of historical buildings, ancient marble structures and a bridge girder are presented where different levels of radiography were applied.
The detection of defects in aircraft components or parts of a power plant or mines in the ground is connected with the task to distinguish between signals caused be the item searched for and noisy signals from other sources. The reliability of the system is the better the better the system is in detecting the wanted signal and avoiding false alarms caused by noise. It is usual to measure the reliability of diagnostic systems in terms of ROC-curves (Re-ceiver Operating Characteristics) and POD-curves (Probability of Detec-tion). The ROC curves describe the POD versus Probability of False Alarm with growing system sensitivity along the curve. POD curves describe the Probability of Detection for a fixed sensitivity for a variation of item sizes or depths. Reliability of the whole system is always a composition of the physics
and technique, application influences and the human factors. For the scien-tific understanding and possibilities of improvement, decomposition accord-ing to a modular model is helpful. The authors present their experiences with the reliability evaluation of metal detectors for humanitarian demining and an NDT system of mechanized ultrasonic phased array testing of copper welds. The special concern in demining is the influence of soil types, detec-tors and the experiences of human beings.
Tomographie 3D-Radiometry for the Visualisation and Measurement of the Defects of Girth Seams
(2006)
New Digital Radiography Procedure Exceeds Film Sensitivity Considerably in Aerospace Applications
(2006)
Some of the most perfidious remnants of war are mines threatening not
only combating parties but also innocent civilian lives. Moreover, they make large
areas inaccessible that otherwise could be used economically. This threat exists
even long after cessation of hostile actions. Up to now, the range of tools for humanitarian
demining is confined to mine detection dogs, metal detectors, prodders,
manual excavation tools and mechanical clearance machines (flails and tillers). In
1999, this gave rise for the Board of Directors of the EFNDT to suggest whether
detection methods commonly applied may also be helpful in detecting mines and the
like. It was proposed to transfer existing NDT technology to these areas. As a consequence,
Working Group 5 Antipersonnel Landmine Detection (APLD) was
founded to support this concept. As soon as the group became aware of the fact that
mines were encountered not only in the soil but also elsewhere the name was
changed to Antipersonnel Mine Detection (APMD).
It now is becoming more and more obvious that vicious devises such as mines
and bombs threatening lives everywhere represent an increasing risk to everybody.
In contrast, the particular interest in antipersonnel mine detection is decreasing in
favour of general security and safety. However, all these problems have in common
that such devices need to be detected in time, i.e. before they become effective. This
gives reason to extend the scope of the existing Working Group 5 accordingly. It is
of advantage to exchange existing knowledge and there is a chance to keep the
awareness of the mine problem alive by this way.