829 research outputs found
Geological and environmental resources investigations in Egypt using LANDSAT images
There are no author-identified significant results in this report
Acceleration and Particle Field Interactions of Cosmic Rays I: Formalism
The acceleration of ultra high energy cosmic rays is conjectured to occur
through various interactions with the electromagnetic fields in different
astrophysical objects, like magnetic matter clumps, besides the well-known
shock and stochastic Fermi mechanisms. It is apparent that the latter are not
depending on the particle's charge, quantitatively. Based on this model, a
considerable portion of the dynamics, that derives a charged particle parallel
to a magnetic field and under the influence of a force
, is assumed to be composed of an acceleration by a non-magnetic
force and a gyromotion along direction,
plus drifts in the direction of . The model and its
formalism are introduced. Various examples for drift motions and accelerating
forces are suggested. The formalism is given in a non-relativistic version.
Obviously, the translation into the relativistic version is standard. In a
forthcoming work, a quantitative estimation of the energy gained by charged
cosmic rays in various astrophysical objects will be evaluated.Comment: 9 pages, 2 EPS figure
Geological and environmental resources investigations in Egypt using LANDSAT images
There are no author-identified significant results in this report
Nonelastomeric Rod Seals for Advanced Hydraulic Systems
Advanced high temperature hydraulic system rod sealing requirements can be met by using seals made of nonelastomeric (plastic) materials in applications where elastomers do not have adequate life. Exploratory seal designs were optimized for advanced applications using machinable polyimide materials. These seals demonstrated equivalent flight hour lives of 12,500 at 350 F and 9,875 at 400 F in advanced hydraulic system simulation. Successful operation was also attained under simulated space shuttle applications; 96 reentry thermal cycles and 1,438 hours of vacuum storage. Tests of less expensive molded plastic seals indicated a need for improved materials to provide equivalent performance to the machined seals
Goertler instability in compressible boundary layers along curved surfaces with suction and cooling
The Goertler instability of the laminar compressible boundary layer flows along concave surfaces is investigated. The linearized disturbance equations for the three-dimensional, counter-rotating streamwise vortices in two-dimensional boundary layers are presented in an orthogonal curvilinear coordinate. The basic approximation of the disturbance equations, that includes the effect of the growth of the boundary layer, is considered and solved numerically. The effect of compressibility on critical stability limits, growth rates, and amplitude ratios of the vortices is evaluated for a range of Mach numbers for 0 to 5. The effect of wall cooling and suction of the boundary layer on the development of Goertler vortices is investigated for different Mach numbers
mesons in a Bethe-Salpeter model
We apply our Bethe-Salpeter model for mesons to the family with
parameters fixed in our previous investigation. We evaluate the mass of the
pseudo-scalar meson as 6.356 GeV/ and 6.380 GeV/ and the
lifetime as 0.47 ps and 0.46 ps respectively in two reductions of the
Bethe-Salpeter Equation, in good agreement with the recently reported mass of
6.40 0.39 (stat.) 0.13 (syst.) GeV/ and lifetime of
(stat.) 0.03 (syst.) ps by the CDF Collaboration.
We evaluate the decay constant of the meson and compare different
contributions to its decay width.Comment: 9 page
Nonparallel stability of two-dimensional nonuniformly heated boundary-layer flows
An analysis is presented for the linear stability of water boundary-layer flows over nonuniformly flat plates. Included in the analysis are disturbances due to velocity, pressure, temperatures, density, and transport properties as well as variations of the liquid properties with temperature. The method of multiple scales is used to account for the nonparallelism of the mean flow. In contrast with previous analyses, the nonsimilarity of the mean flow is taken into account. No analysis agrees, even qualitatively, with the experimental data when similar profiles are used. However, both the parallel and nonparallel results qualitatively agree with the experimental results of Strazisar and Reshotko when nonsimilar profiles are used
- …