Tunable Security for Deployable Data Outsourcing

Security mechanisms like encryption negatively affect other software quality characteristics like efficiency. To cope with such trade-offs, it is preferable to build approaches that allow to tune the trade-offs after the implementation and design phase. This book introduces a methodology that can be used to build such tunable approaches. The book shows how the proposed methodology can be applied in the domains of database outsourcing, identity management, and credential management

FTS-based face milling of micro structures

This article presents a technical concept and machining possibilities for milling of micro structures with a fast tool servo (FTS). The tool is capable of tool tip displacements with a variable frequency up to 4000 Hz and an amplitude up to 30 μm. The control system of the actuator is linked to the angular spindle position, allowing to freely manipulate the excitation signal. Combining this tool system with a single tooth face milling head, micro structures on flat surfaces can be generated on conventional milling centers. Selected micro structures are machined and evaluated in terms of precision and surface quality.DFG/CRC/65

Effizienz durch Synergien im E-Learning. Zentrale Strukturen und einrichtungsübergreifende Kooperationen an den sächsischen Hochschulen

Die deutschen Hochschulen sind in den letzten Jahren einem in der Historie beispiellosen Reformdruck ausgesetzt. Bologna-Reform, Globalhaushalte, Studiengebühren, Exzellenzinitiativen und Weiterbildungsmarkt sind nur einige der omnipräsenten Stichworte. Die zunehmende Einführung von technologiegestützten Lehr- und Lernmethoden erlaubt den Hochschulakteuren die Flankierung dieser Neuordnungen und zusätzliche strategische Positionierungen. Die Hochschulen des Freistaates Sachsen verfolgen, unterstützt durch das Staatsministerium für Wissenschaft und Kunst (SMWK), spezielle E-Learning-Strategien mittels einrichtungsübergreifender Kooperationen. Verkörpert werden diese durch gemeinsame Lenkungs- und Dienstleistungsstrukturen ebenso wie durch die übergreifende Koordination von E-Learning-Projekten und den Einsatz einer einheitlichen Lernplattform. Der vorliegende Beitrag thematisiert die landesweite E-Learning-Entwicklung im Freistaat Sachsen. Dabei werden vor dem Hintergrund historischer Entwicklungen mit dem Arbeitskreis E-Learning der Landesrektorenkonferenz Sachsen (ehemals Landeshochschulkonferenz), der BPS Bildungsportal Sachsen GmbH und der Lernplattform OPAL die zentralen Strukturen der Politik-, Service- und Technologieebene charakterisiert. Zudem werden praktische Arbeitsbereiche vorgestellt, in denen hochschulübergreifende Kooperationen stattfinden. Der abschließende Ausblick verweist auf Entwicklungstendenzen sowie laufende und zukünftige Maßnahmen zur Verbreitung der E-Learning-Nutzung an den Hochschulen des Freistaates Sachsen. (DIPF/ Orig.

Residual stresses in milled β-annealed Ti6Al4V

Residual stresses can cause part distortion especially in the case of large components such as structural parts in aerospace industry. Therefore, this paper investigates the machining induced residual stresses for milling of a workpiece material with increasing usage in industry, the β-annealed titanium alloy Ti6Al4V. This thermal treatment results in a large grained material structure. For this reason X-ray diffraction, the standard residual stress measurement method, cannot be used for stress determination. In this paper an adopted indirect measurement method, the layer removal method is discussed. With respect to the material removal, two different methods are investigated, electrochemical material removal and laser ablation. Finally, the influence of the tool wear on the residual stress state after face milling is analyzed.Lower Saxony Ministry for Economics, Labour and TransportPremium Aerotec GmbH, Vare

Prediction of process forces and stability of end mills with complex geometries

In order to optimize the cutting performance of end mills, the geometry of such cutters is optimized by toolmakers constantly. As a result of geometric changes, process forces can be reduced, i.e. by serrated end mills. Tools with unequal helix angles can lead to an increase of process stability. In this paper, a method to calculate the process forces of end mills with complex geometries is presented. The method for calculating the process forces is designed for the application for stability analysis of end mill cutters with complex geometries. A basic introduction of the method for the stability prediction of such tools is given. Cutting forces of end mills are analyzed at incremental axial depth of cuts to show the influence of the tool geometry on the process forces. The comparison with experimental data verifies this method and shows the influence of further effects on the process forces. Furthermore, stability charts obtained with the Semi-Discretization Method are presented to show the potential of end mills with complex geometries regarding stability improvement.Ministry for Science and Culture of Lower Saxony (MWK

Grinding of Iron-aluminides

AbstractSince the 1930s iron-aluminides are investigated due to their excellent corrosion resistance, low density and high specific strength. However, little work has been carried out on the machining of these alloys since then. This paper deals with grinding of Fe-26Al- 4Cr (at.%) with corundum grinding wheels and shows that the material can be machined in a ductile way, regardless of the material grain size. Material removal rates below Qw = 0.75 mm3/mms and open grinding wheel topographies lead to low grinding temperatures and an advantageous chip removal. Thus, high process reliability regarding workpiece quality and tool wear can be reached

Untersuchungen zur Pharmakokinetik und Pharmakodynamik verschiedener galenischer Formulierungen des Immunsuppressivums Cyclosporin A vor und nach Nierentranplantation an Ratten

Ziel der Arbeit war der Vergleich der therapeutischen Äquivalenz des Immunsuppressivums Sandimmun Neoral mit zwei Generika, Gengraf und CsA Eonlabs. Es konnten siqnifikante Unterschiede im first-pass Metabolismus zwischen den drei Pharmaka festgestellt werden. Des Weiteren wurden Untersuchungen zum Metabolismus des Cyclosporin A und verschiedenen mRNA Abundanzen in den Nieren nach Nierentransplantation in Ratten durchgeführt

High-performance cutting of micro patterns

This research report presents an innovative piezo-actuated fast tool servo (FTS) for milling operations introducing the highperformance cutting of micro patterns. The outstanding dynamics of the tool enable a highly dynamic depth of cut variation during the cutting process. Unlike commercial technologies, such as ultrasonic tools, the presented device does not oscillate in resonance, but controlled. Its first natural resonance frequency of ?0 > 4.5 kHz and its capability to provide a maximum amplitude of ▵lmax > 30 microns establish the basis to cut micro patterns, while using process parameters applied in real-life industrial processes.DFG/CRC/65

Elementary studies on the inducement and relaxation of residual stress

In order to qualify residual stress relaxation as an indicator of mechanical overloading of machined parts, an individually designed residual stress profile has to be allocated. Even though numerous investigations have been carried out in the past, residual stress profiles cannot be predicted to a satisfactory degree. For this reason, essential studies on the reproducibility of residual stress profiles for several external cylindrical turning parameters are conducted and it is demonstrated that identical residual stress profiles can be induced successfully. Subsequently, specimens with defined residual stress profiles are loaded in bending tests with various numbers of test cycles. The amount of residual stress relaxation in the specimen's surface layer is measured to determine the influence of theapplied load on the stress relaxation. By applying single tensile and compressive loads below and above thematerial's yield and ultimate strength, the stress relaxation can be evaluated in detail.DFG/CRC/SFB/65