Investigation of the speed-up of a dual microcontroller parallel processing system in the execution of a mathematical operation

An investigation of the performance of a two microcontroller parallel processing system is presented. A twomicrocontroller parallel processing is developed using low end microcontrollers (PIC 16F877). An 8x8 bit multiply operation and a 16x16 bit multiply operation are executed on a single microcontroller and on the proposed dual microcontroller parallel processing system in order to assess the performance of the proposed system. Results presented show poor performance for the 8x8 bit multiply with an average speed up factor of 0.82 This is due to the time required to transfer data around the dual microcontroller system being significant in comparison to the time required to complete the multiply operation, thus nullifying the potential advantage that might be expected of a dual microcontroller system. The 16x16 multiplier exhibited good performance, with results showing a maximum average speed up factor of 1.7 and an average speed up factor of 1.5. The 16x16 multiplication requires longer time to compute and the data transfer time between microcontrollers whilst still having an impact on the overall computation time is significantly less than for the 8x8 multiplier A formula has been developed to provide an estimate of the possible speed up within a system in relation to the process execution time and the time required to communicate data around the proposed system. The proposed system was developed and tested using the Proteus simulation software

The Complexity of Orbits of Computably Enumerable Sets

The goal of this paper is to announce there is a single orbit of the c.e. sets with inclusion, \E, such that the question of membership in this orbit is $\Sigma^1_1$-complete. This result and proof have a number of nice corollaries: the Scott rank of \E is \wock +1; not all orbits are elementarily definable; there is no arithmetic description of all orbits of \E; for all finite $\alpha \geq 9$, there is a properly $\Delta^0_\alpha$ orbit (from the proof). A few small corrections made in this versionComment: To appear in the Bulletion of Symbolic Logi

Lyman alpha Resonant Scattering in Young Galaxies - Predictions from Cosmological Simulations

We present results obtained with a 3D, Ly alpha radiative transfer code, applied to a fully cosmological galaxy formation simulation. The developed Monte Carlo code is capable of treating an arbitrary distribution of source Ly alpha emission, neutral hydrogen density, temperature, and peculiar velocity of the interstellar medium. We investigate the influence of resonant scattering on the appearance and properties of young galaxies by applying the code to a simulated "Lyman Break Galaxy" at redshift z = 3.6, and of star formation rate 22 M_sun/yr and total Ly alpha luminosity 2.0 X 10^43 erg/s. It is found that resonant scattering of Ly alpha radiation can explain that young galaxies frequently are observed to be more extended on the sky in Ly alpha than in the optical. Moreover, it is shown that, for the system investigated, due to the anisotropic escape of the photons, the appearent maximum surface brightness can differ by a factor of ~15, and the total derived luminosity by a factor of ~4, depending on the orientation of the system relative to the observer.Comment: Letter updated to match version published in Ap