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MPI collective operations are implemented using a variety of algorithms which define different communication patterns between the ranks involved in the operation. The performance of these algorithms in multi-core clusters highly depends on the mapping of the ranks to the system processors due to the uneven capabilities of shared memory and network channels. The hierarchical design of these algorithms...
The problem of synthesizing a linear array generating a shaped beam pattern with M filled nulls has 2M alternative solutions. The sensitivity of the performance to errors in element position, excitation phase or amplitude of the solutions provided by the synthesis of a flat-topped beam pattern using an array of 16 isotropic elements spaced λ/2 was analysed.
The geometry of a planar array of parasitic dipoles is optimized to modify the pattern of an active dipole above a ground plane, in order to obtain a pencil beam of moderate gain and bandwidth without requiring a complex feeding network. As an example of application, a pencil beam pattern radiated by a planar array of parasitic dipoles fed by only one active dipole at 1.645 GHz is shown.
This paper shows that linear arrays with the design described in the title can outperform both uniformly spaced arrays and nonuniformly spaced arrays designed by other published methods. The linear model can be extended to planar arrays in ways that achieve excellent antenna performance while preserving the efficiency of the optimization procedure used in the design process.
In recent years, satellite overlay networks have shown their potential for delivering multimedia content both to rural and urban environments. In the latter case, the adoption of terrestrial intermediate module repeaters (IMRs) is in order to close the link in non-line-of-sight propagation conditions, causing a severe increase of multipath propagation and consequent linear distortion, adding to the...
This work is about different optimal solutions for the unit commitment problem in the Venezuelan hydrothermal power system, disregarding the transmission system. The centralized cost-based maximum net social benefit solution, the oligopoly solution and the unregulated monopoly solution are formulated and analyzed. The oligopoly is studied via Nash-Cournot equilibrium, obtained iteratively considering...
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