Simplified approach to the application of the geometric collective model

The predictions of the geometric collective model (GCM) for different sets of Hamiltonian parameter values are related by analytic scaling relations. For the quartic truncated form of the GCM -- which describes harmonic oscillator, rotor, deformed gamma-soft, and intermediate transitional structures -- these relations are applied to reduce the effective number of model parameters from four to two. Analytic estimates of the dependence of the model predictions upon these parameters are derived. Numerical predictions over the entire parameter space are compactly summarized in two-dimensional contour plots. The results considerably simplify the application of the GCM, allowing the parameters relevant to a given nucleus to be deduced essentially by inspection. A precomputed mesh of calculations covering this parameter space and an associated computer code for extracting observable values are made available through the Electronic Physics Auxiliary Publication Service. For illustration, the nucleus 102Pd is considered.Comment: RevTeX 4, 15 pages, to be published in Phys. Rev.

Evaluation of ultrasonic volume- and underclad indications at long distances

Analysis techniques are applied in UT examinations if the standard examination provides unacceptable indications and more exact parameters are required for the fracture mechanics evaluation. The necessity for analysis techniques is particularly great where long distances are involved, i.e. when sensitivity is too limited for crack tip detection or when focusing at the reflector location is insufficient, in order to correct the results of the standard, which are often too conservative. There are manual analysis procedures, using focusing transducers or time of flight reconstruction methods, and mechanized, computer-assisted procedures, based on the synthetic aperture principle. ALOK and SAFT measurements were performed by the IzfP (NDE Institute) and KWU on volume flaws and findings near the cladding. The results show that, compared with manual measurements, the computer-assisted methods have the advantage that the complete B-scan representation enables better interpretation of the exam ination interpretation of the examination results, thereby avoiding evaluation errors in individual cases. ALOK reconstruction have the advantage that they can be interpreted in the same way as a manual analysis, thus facilitating for the UT examiner the transition from the manual to the computer-assisted imaging method. Better image reproduction is a feature of the L Saft reconstructions. Virtual independance from examination parameters is also advantageous

Der getaktete Gruppenstrahler - ein neues Verfahren zur Signalverarbeitung und Bildrekonstruktion in der zerstörungsfreien Ultraschallprüfung

Der 'getaktete Gruppenstrahler' ermöglicht neuartige Ansätze bei der Entwicklung und Anwendung von Ultraschallprüfsystemen. Es wurde im IZFP eine Entwicklungsplattform gebaut, mit folgenden Systemverbesserungen im Vergleich zum derzeitigen Stand der Technik. 1. Erhöhung der Prüfgeschwindigkeit bei verbesserter Aussagekraft mit der Möglichkeit zur Integration der Prüfsysteme in Fertigungslinien (Prüfgeschwindigkeiten bis zu einigen Metern pro Sekunde) 2. Quantitative Bildgebung unter Echtzeit-Bedingungen 3. Verbesserung der Prüfbarkeit von 'schlecht' prüfbaren Materialien wie z.B. inhomogene anisotrope Werkstoffe (Kohlefaser, austenitische Stähle und Schweißverbindungen) 4. Preiswertere Prüfelektronik auf der Basis moderner mikroelektronischer Technologien und durch den Entfall der 'Phasenschieberelektronik' 5. Erfüllung nationaler und internationaler Regelwerksanforderunge

Sampling phased array: A new method of signal processing and image reconstruction in ultrasonic non-destructive testing

Different signal processing and image reconstruction techniques are applied in ultrasonic non-destructive material evaluation. In recent years, rapid development in the fields of microelectronics and computer engineering lead to wide application of phased array systems. A new phased array technique, called "Sampling Phased Array" has been developed in Fraunhofer Institute for non-destructive testing. It realizes unique approach of measurement and processing of ultrasonic signals. The sampling phased array principle make use of the measurement of elementary waves generated by individual elements of sensor array to reconstruct the composite phased array signal for any arbitrary angle or focus depth. The use of special signal processing and image reconstruction algorithms, allows generating A-Scans of several angles and / or Sector-Scan, which can be implemented in real time. With parallel computing structures, this principle is used for automatic testing systems at very high inspection speed. A comparative study was done with Conventional Phased Array system and Sampling Phased Array technique. The study shows that the signal characteristics in both techniques are equal. In addition, the Sampling Phased Array technique is significantly beneficial in the many aspects like quality of information in specific cases, inspection speeds and adaptability to specific inspection tasks in comparison to conventional Phased Array. The electronics was developed as a development platform for high speed automated ultrasonic inspection systems for process integrated testing and also for testing of critical components. The development results, including relevant test methodology and electro-technical/electronic aspects are presented in the current work