Kinematical and mechanical aspects of wafer slicing

Some recently achieved results concerning the technological fundamentals of slurry sawing are presented. The specific material removal process and the related kinematic and geometric contact conditions between workpiece and saw blade are described. The result of a functional description of the slurry sawing process is presented, expressing the main process criteria, such as infeed per stroke, specific removal rate, specific tool wear, and vertical stroke intensity, in terms of the dominating process parameters, such as stroke length, width of workpiece, stroke frequency, specific cutting force and slurry specification

Maximal Subrings and Covering Numbers of Finite Semisimple Rings

We classify the maximal subrings of the ring of nx n matrices over a finite field, and show that these subrings may be divided into three types. We also describe all of the maximal subrings of a finite semisimple ring, and categorize them into two classes. As an application of these results, we calculate the covering number of a finite semisimple ring

Circular 91

Plants of Begonia x tuberhybrida ‘Nonstop’, ‘Clips’, and ‘Musical’ were exposed to 1, 2, 3, or 4 weeks of short days (SD, 9 hours day length) initiated at 3 stages of plant development (immediately upon germination, 4 or 8 weeks after germination). Prior to and succeeding short days, plants were exposed to long days (LD, 16 hours day length). Musical flowered on average 68 days, Clips 78 days and Nonstop 83 days after germination under continuous LD conditions. In Nonstop, SD for 1, 2, 3, or 4 weeks delayed plant development by an average 12 days compared to LD grown plants. One, 2, or 3 weeks of SD resulted in 1 week slower flowering and 4 weeks of SD resulted in 2 weeks later flowering in Clips. The sensitivity to SD varied with plant stage in Musical. Three or 4 weeks of SD initiated at germination or 4 weeks after germination resulted in an average delayed flowering of 13 days compared to LD plants. SD initiated 8 weeks after germination had no effect on rate of development in Musical

Element Abundance Determination in Hot Evolved Stars

The hydrogen-deficiency in extremely hot post-AGB stars of spectral class PG1159 is probably caused by a (very) late helium-shell flash or a AGB final thermal pulse that consumes the hydrogen envelope, exposing the usually-hidden intershell region. Thus, the photospheric element abundances of these stars allow us to draw conclusions about details of nuclear burning and mixing processes in the precursor AGB stars. We compare predicted element abundances to those determined by quantitative spectral analyses performed with advanced non-LTE model atmospheres. A good qualitative and quantitative agreement is found for many species (He, C, N, O, Ne, F, Si, Ar) but discrepancies for others (P, S, Fe) point at shortcomings in stellar evolution models for AGB stars. Almost all of the chemical trace elements in these hot stars can only be identified in the UV spectral range. The Far Ultraviolet Spectroscopic Explorer and the Hubble Space Telescope played a crucial role for this research.Comment: To appear in: Recent Advances in Spectroscopy: Theoretical, Astrophysical, and Experimental Perspectives, Proceedings, Jan 28 - 31, 2009, Kodaikanal, India (Springer