1,429 research outputs found
Molding procedure for casting a variety of alloys
General procedure and molding sand composition for preparing molds usable for casting variety of alloys are developed. Molds are prepared from mixture of sand, sodium silicate binder, and organic liquid ester. Castings of radiographic quality are produced from various alloys
Perfil socioeconomico dos produtores familiares de laranja de Umbauba, Sergipe.
bitstream/item/87918/1/CPATC-PESQ.-AND.-18-97.pd
Excited States in Warm and Hot Dense Matter
Accurate modeling of warm and hot dense matter is challenging in part due to
the multitude of excited states that must be considered. In thermal density
functional theory, these excited states are averaged over to produce a single,
averaged, thermal ground state. Here we present a variational framework and
model that includes explicit excited states. In this framework an excited state
is defined by a set of effective one-electron occupation factors and the
corresponding energy is defined by the effective one-body energy with an
exchange and correlation term. The variational framework is applied to an
atom-in-plasma model (a generalization of the so-called average atom model).
Comparisons with a density functional theory based average atom model generally
reveal good agreement in the calculated pressure, but the new model also gives
access to the excitation energies and charge state distributions
Augmented collisional ionization via excited states in XUV cluster interactions
The impact of atomic excited states is investigated via a detailed model of
laser-cluster interactions, which is applied to rare gas clusters in intense
femtosecond pulses in the extreme ultraviolet (XUV). This demonstrates the
potential for a two-step ionization process in laser-cluster interactions, with
the resulting intermediate excited states allowing for the creation of high
charge states and the rapid dissemination of laser pulse energy. The
consequences of this excitation mechanism are demonstrated through simulations
of recent experiments in argon clusters interacting with XUV radiation, in
which this two-step process is shown to play a primary role; this is consistent
with our hypothesis that XUV-cluster interactions provide a unique window into
the role of excited atomic states due to the relative lack of photoionization
and laser field-driven phenomena. Our analysis suggests that atomic excited
states may play an important role in interactions of intense radiation with
materials in a variety of wavelength regimes, including potential implications
for proposed studies of single molecule imaging with intense X-rays.Comment: 4 pages, 2 figure
Relação com a terra e estratégias fundiárias dos produtores familiares de Ummbaúba-SE.
bitstream/item/90510/1/CPATC-PESQ.-AND.-36-98.pd
- …