10,562 research outputs found
A new species of Boettcheria from Guatemala (Diptera: Sarcophagidae)
Boettcheria styx new species is described from Guatemala, and a key is provided to separate it from B. maerens (Townsend). A list is given of Central American species of Boettcheria with references to figures of their genitalia
Coherent Description for Hitherto Unexplained Radioactivities by Super- and Hyperdeformed Isomeric States
Recently long-lived high spin super- and hyperdeformed isomeric states with
unusual radioactive decay properties have been discovered. Based on these newly
observed modes of radioactive decay, consistent interpretations are suggested
for previously unexplained phenomena seen in nature. These are the Po halos,
the low-energy enhanced 4.5 MeV alpha-particle group proposed to be due to an
isotope of a superheavy element with Z = 108, and the giant halos.Comment: 8 pages, 2 figures, 1 table, to be published in Int. J. Mod. Phys.
Super- and Hyperdeformed Isomeric States and Long-Lived Superheavy Elements
The recent discoveries of the long-lived high spin super- and hyperdeformed
isomeric states and their unusual radioactive decay properties are described.
Based on their existence a consistent interpretation is given to the production
of the long-lived superheavy element with Z = 112, via secondary reactions in
CERN W targets, and to the low energy and very enhanced alpha-particle groups
seen in various actinide fractions separated from the same W target. In
addition, consistent interpretations are suggested for previously unexplained
phenomena seen in nature. These are the Po halos, the low-energy enhanced 4.5
MeV alpha-particle group proposed to be due to an isotope of a superheavy
element with Z = 108, and the giant halos.Comment: 4 pages. Contribution to the 2nd Int. Conf. on the Chemistry and
Physics of the Transactinide Elements (TAN 03) Napa California, November 200
Alpha radioactivity of E > 11 MEV in nature
Alpha particles with energies greater than those so far reported to occur in nature have been observed in minerals by emulsion and counting techniques
Increasing productivity in heavy machining using a simulation based optimization method for porcupine milling cutters with a modified geometry
Porcupine milling cutters offer a high potential for increasing the metal removal rate in heavy machining of steel and titanium. Here, the available machine power and the maximum radial force represent important process limits. According to the current state of the art, mainly rectangular indexable inserts are used. Investigations show that the use of round inserts can significantly reduce the resulting radial force and cutting torque similar to serrated endmills. However, the design of such tools is a major challenge due to the complicated shape of cross-section of the undeformed chip. Therefore, this paper presents a new method for optimizing the position of individual indexable inserts by means of geometric material removal simulations. With the new method, the radial force can be reduced by 14%
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