6,515 research outputs found
A view of software development environment issues
The unique and challenging nature of the Space Station Program requires that software standards be effectively used to control costs, facilitate enhancements and ensure safety. The Software Standards Panel identified and developed recommendations in four areas to help the Space Station Program achieve these objectives. The areas in which recommendations are offered are policy, organization, process and candidate software standards for the Space Station Program. The concensus process employed by the panel is given and recommendations are made
On Modeling and Analyzing Cost Factors in Information Systems Engineering
Introducing enterprise information systems (EIS) is usually associated with high costs. It is therefore crucial to understand those factors that determine or influence these costs. Though software cost estimation has received considerable attention during the last decades, it is difficult to apply existing approaches to EIS. This difficulty particularly stems from the inability of these methods to deal with the dynamic interactions of the many technological, organizational and projectdriven cost factors which specifically arise in the context of EIS. Picking up this problem, we introduce the EcoPOST framework to investigate the complex cost structures of EIS engineering projects through qualitative cost evaluation models. This paper extends previously described concepts and introduces design rules and guidelines for cost evaluation models in order to enhance the development of meaningful and useful EcoPOST cost evaluation models. A case study illustrates the benefits of our approach. Most important, our EcoPOST framework is an important tool supporting EIS engineers in gaining a better understanding of the critical factors determining the costs of EIS engineering projects
Casimir effects in graphene systems: unexpected power laws
We present calculations of the zero-temperature Casimir interaction between
two freestanding graphene sheets as well as between a graphene sheet and a
substrate. Results are given for undoped graphene and for a set of doping
levels covering the range of experimentally accessible values. We describe
different approaches that can be used to derive the interaction. We point out
both the predicted power law for the interaction and the actual distance
dependence.Comment: 10 pages,5 figures, conferenc
Beneficial and Harmful Agile Practices for Product Quality
There is the widespread belief that Agile neglects the product quality. This
lack of understanding how Agile processes assure the quality of the product
prevents especially companies from regulated domains from an adoption of Agile.
This work aims to identify which Agile Practices contribute towards product
quality. Hence, data from a survey study is analyzed to identify Ag-ile
Practices which are beneficial or harmful for the quality of the product. From
49 practices that were used in the survey so far, 36 were perceived to have a
positive impact on product quality, while four practices were rated as being
harmful. The results enrich understanding of how product quality can be
achieved in Agile, and support selection of practices to improve quality
Spin-wave spectrum of copper metaborate in the commensurate phase 10K<T<21K
We have investigated the spin-wave spectrum of copper metaborate,
CuBO, by means of inelastic neutron scattering in the commensurate
magnetic phase. We have found two branches of spin-wave excitations associated
with the two magnetic sublattices Cu(A) and Cu(B), respectively. In the
temperature regime , where only the Cu(A) magnetic moments
are ordered, the interaction between the two sublattices is found to be
negligible. With this approximation we have determined the `easy plane'
exchange parameters of the Cu(A) subsystem within standard spin-wave theory.Comment: 4 figure
Casimir interactions in graphene systems
The non-retarded Casimir interaction (van der Waals interaction) between two
free standing graphene sheets as well as between a graphene sheet and a
substrate is determined. An exact analytical expression is given for the
dielectric function of graphene along the imaginary frequency axis within the
random phase approximation for arbitrary frequency, wave vector, and doping.Comment: 4 pages, 4 figure
Internal kinematics of isolated modelled disk galaxies
We present a systematic investigation of rotation curves (RCs) of fully
hydrodynamically simulated galaxies, including cooling, star formation with
associated feedback and galactic winds. Applying two commonly used fitting
formulae to characterize the RCs, we investigate systematic effects on the
shape of RCs both by observational constraints and internal properties of the
galaxies. We mainly focus on effects that occur in measurements of intermediate
and high redshift galaxies. We find that RC parameters are affected by the
observational setup, like slit misalignment or the spatial resolution and also
depend on the evolution of a galaxy. Therefore, a direct comparison of
quantities derived from measured RCs with predictions of semi-analytic models
is difficult. The virial velocity V_c, which is usually calculated and used by
semi-analytic models can differ significantly from fit parameters like V_max or
V_opt inferred from RCs. We find that V_c is usually lower than typical
characteristic velocities derived from RCs. V_max alone is in general not a
robust estimator for the virial mass.Comment: 9 pages, 15 figures, accepted for publication in A&
Light spin-1/2 or spin-0 Dark Matter particles
We recall and precise how light spin-0 particles could be acceptable Dark
Matter candidates, and extend this analysis to spin-1/2 particles. We evaluate
the (rather large) annihilation cross sections required, and show how they may
be induced by a new light neutral spin-1 boson U. If this one is vectorially
coupled to matter particles, the (spin-1/2 or spin-0) Dark Matter annihilation
cross section into e+e- automatically includes a v_dm^2 suppression factor at
threshold, as desirable to avoid an excessive production of gamma rays from
residual Dark Matter annihilations. We also relate Dark Matter annihilations
with production cross sections in e+e- scatterings. Annihilation cross sections
of spin-1/2 and spin-0 Dark Matter particles are given by exactly the same
expressions. Just as for spin-0, light spin-1/2 Dark Matter particles
annihilating into e+e- could be responsible for the bright 511 keV gamma ray
line observed by INTEGRAL from the galactic bulge.Comment: 10 page
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