34,967 research outputs found
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 âNonstopâ, âClipsâ, and âMusicalâ 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
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