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Eingeladener Vortrag
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Testing for safety
(2002)
BAM is the competent authority for testing and analyses and quality assurance in certification procedures for containers which transport radioactive substances. If a manufacturer requests the approval for a type of container, BAM performs the stipulated tests. Approvals granted by the Federal Office for Radiation Protection (BfS) are based on the official test certificate issued by BAM. In addition, BAM is the competent authority for the approval of special types of radioactive substances, "radioactive substances in special form". These are used in medical instruments for example.
Prüfung für Sicherheit
(2002)
In Zulassungsverfahren für Behälter zur Beförderung radioaktiver Stoffe ist die BAM zuständig für Prüfungen und Analysen und für die Qualitätssicherung. Beantragt ein Hersteller die Zulassung für einen Behältertyp, führt die BAM die vorgeschriebenen Prüfungen durch. Das amtliche Prüfzeugnis der BAM dient dann dem BfS als Grundlage für die Erteilung der Zulassung. Darüber hinaus ist die BAM zuständige Behöre für die Zulassung eines speziellen Typs von radioaktiven Stoffen, den "radioaktiven Stoffen in besonderer Form". Diese finden z. B. in medizinischen Geräten Verwendung.
XTEM and TFXRD investigations of ohmic Ti/Al/Ti/Au/WSiN contacts on AlGaN/GaN HFET layer systems
(2002)
The microstructural features of the high-temperature-stable ohmic contact system Ti/Al/Ti/Au/WSiN on AlGaN/GaN were investigated using analytical transmission electron microscopy and thin film x-ray diffraction.
For two typical rapid thermal annealing steps at 750 ◦C (non-ohmic behaviour) and 850 ◦C (ohmic behaviour) the intermetallic phases at the metal–semiconductor interface are presented. Increased annealing leads to the transformation of an Al2Au-AlAuTi phase mixture to a mixture of Al2Au-Al3Au8 phases and the formation of Ti-Al-nitride layers at the interfaces. In light of these results the electrical contact properties are discussed.
Disc brakes are widely used in cars, trains, and other vehicles. For understanding the basic processes occurring during the friction process, information on the surface topography of brake pads and discs is needed, in addition to information about chemistry and thermodynamics. In this paper, samples of pads and discs were analysed using white light interferometry. The topography of the surfaces was measured quantitatively. Using software tools described in a previous paper [Wear 248 (2001) 121], the distributions of area, height, and slope of the contact patches were computed. Characteristic properties of the contact patches were found to describe the influence of the test parameters such as friction power and testing time.
The program PowderCell is a crystallographic tool for visualization of Crystal structures. However, it offers also non-conventional features like the fulautomatical generation of subgroups or the consideration of non-standard settings of space-group types. On the one Hand the program is very useful for non-crystallographers who like to get an impression of the atomic arrangement within the unit cell. But also for crystallographers it is recommendable because it contains a lot of additional information which can be extracted and used like data given in the International Tables for Crystallography, Vol. A. However, the most important advantage of the program is the simultaneous calculation of the X-ray or neutron diffraction powder patterns for a mixture of up to 10 crystalline phases. Between more than 7 different characteristic radiations can be chosen and their influence on the resulting powder pattern can be studied. Furthermore, experimental diffractograms can be analysed using a refinement procedure. The implemented LeBail-algorithm allows the investigation of unknown phases. In combination with the refinement algorithm an interface to Shelx offers the possibility for a step by step ab initio structure analysis. Certainly, the user-friendly shell is one reason that especially users who are not so familar with space-group symmetry, crystal structure data or diffractometry use this powerful tool for the solution of scientific or analytical problems as well as in teaching.
X-ray stress analysis on crystalline materials is based on the determination of elastic lattice strains. The strains described by the shift of peak positions are converted to stresses by the means of theory of elasticity. The development of the sin2ψ-method of X-ray stress analysis introduced an enormous progress in X-ray stress analysis during the last decades. This report outlines some important elements of X-ray physics and fundamentals of theory of elasticity. The Standard measuring procedure are described and special experimental differences to the common powder diffractometry are outlined.