6,026 research outputs found
Recommended approach to sofware development
A set of guideline for an organized, disciplined approach to software development, based on data collected and studied for 46 flight dynamics software development projects. Methods and practices for each phase of a software development life cycle that starts with requirements analysis and ends with acceptance testing are described; maintenance and operation is not addressed. For each defined life cycle phase, guidelines for the development process and its management, and the products produced and their reviews are presented
A New Light Higgs Boson and Short-Baseline Neutrino Anomalies
The low-energy excesses observed by the MiniBooNE experiment have, to date,
defied a convinc- ing explanation under the standard model even with
accommodation for non-zero neutrino mass. In this paper we explore a new
oscillation mechanism to explain these anomalies, invoking a light neu-
trinophilic Higgs boson, conceived to induce a low Dirac neutrino mass in
accord with experimental limits. Beam neutrinos forward-scattering off of a
locally over-dense relic neutrino background give rise to a novel matter-effect
with an energy-specific resonance. An enhanced oscillation around this
resonance peak produces flavor transitions which are highly consistent with the
MiniBooNE neutrino- and antineutrino-mode data sets. The model provides
substantially improved values beyond either the no-oscillation
hypothesis or the more commonly explored 3+1 sterile neutrino hy- pothesis.
This mechanism would introduce distinctive signatures at each baseline in the
upcoming SBN program at Fermilab, presenting opportunities for further
exploration.Comment: 11 pages, 6 figures, submitted to PR
Designing with Ada for satellite simulation: A case study
A FORTRAN-operated and an Ada-oriented design for the same system are compared to learn whether an essentially different design was produced using Ada. The designs were produced by an experiment that involves the parallel development of software for a spacecraft dynamics simulator. Design differences are identified in the use of abstractions, system structure, and simulator operations. Although the designs were significantly different, this result may be influenced by some special characteristics discussed
Designing with Ada for satellite simulation: A case study
A FORTRAN oriented and an Ada oriented design for the same system are compared to learn whether an essentially different design was produced using Ada. The designs were produced by an experiment that involves the parallel development of software for a spacecraft dynamics simulator. Design differences are identified in the use of abstractions, system structure, and simulator operations. Although the designs were vastly different, this result may be influenced by some special characteristics discussed
Ballistic thermal conductance limited by phonon roughness scattering: A comparison of power-law and Gaussian roughness
In this work, we have investigated the influence of power-law roughness on the ballistic thermal conductance KTH for a nanosized beam adiabatically connected between two heat reservoirs. The sideways wall beam roughness is assumed to be power-law type, which is described by the roughness amplitude w, the in-plane roughness correlation length ξ and the roughness exponent 0≤H≤1. Distinct differences occur in between power-law and Gaussian wall roughness. For power-law roughness with low roughness exponents H (<0.5), the influence of phonon scattering can be rather destructive leading to significant deviations from the universal conductance value for flat beam walls. On the other hand for large roughness exponents (H>0.5) the conductance drop is significantly smaller than that of Gaussian roughness assuming similar roughness ratios w/ξ.
The Energy Dependence of the Aperiodic Variability for Cygnus X-1, GX 339-4, GRS 1758-258, & 1E 1740.7-2942
Using the data from the Rossi X-ray Timing Explorer (RXTE), we report the
different energy dependence of the variability of the four persistent hard
X-ray sources in the low-hard state: Cygnus X-1, GX 339-4, GRS 1758-258 and 1E
1740.7-2942. Cygnus X-1 is found to have a flatter power density spectrum (PDS)
shape at higher energies. The other three sources have energy independent PDS
shapes. The energy dependence of the overall variability (the integrated rms
amplitude) varies from source to source and from observation to observation.
1E~1740.7-2942, for example, has a variability generally increasing with energy
while GX 339-4 has a decreasing variability. A general trend is found in the
four sources that the integrated rms amplitude anti-correlates with the X-ray
flux. We compare these distinct energy dependent behaviors with several
emission models. None of the models can fully explain all the features that we
have found.Comment: 18 pages, 6 figures. Accepted for publication in Ap
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