465 research outputs found
Adaptive data acquisition multiplexing system and method
A reconfigurable telemetry multiplexer is described which includes a monitor-terminal and a plurality of remote terminals. The remote terminals each include signal conditioning for a plurality of sensors for measuring parameters which are converted by an analog to digital converter. CPU's in the remote terminals store instructions for prompting system configuration and reconfiguration commands. The measurements, instructions, and the terminal's present configuration and status data are transmitted to the monitor-terminal and displayed. In response to menu-driven prompts generated and displayed at the monitor-terminal, data generation request commands, status and health commands, and the like are input at the monitor-terminal and transmitted to the remote terminals. The CPU in each remote terminal receives the various commands, stores them in electrically alterable memory, and reacts in accordance with the commands to reconfigure a plurality of aspects of the system. The CPU in each terminal also generates parameter measurements, status and health signals, and transmits these signals of the respective terminals to the monitor-terminal for low data rate operator viewing and to higher rate external transmission/monitor equipment. Reconfiguration may be in real time during the general period of parameter measurement acquisition, and may include alteration of the gain, automatic gain rescaling, bias, and or sampling rates associated with one or more of the parameter measurements made by the remote terminals
Approximate solutions in space mission design
In this paper, we address multi-objective space mission design problems. From a practical point of view, it is often the case that,during the preliminary phase of the design of a space mission, the solutions that are actually considered are not 'optimal' (in the Pareto sense)but belong to the basin of attraction of optimal ones (i.e. they are nearly
optimal). This choice is motivated either by additional requirements that the decision maker has to take into account or, more often, by robustness considerations. For this, we suggest a novel MOEA which is a modification of the well-known NSGA-II algorithm equipped with a recently
proposed archiving strategy which aims at storing the set of approximate solutions of a given MOP. Using this algorithm we will examine some space trajectory design problems and demonstrate the benefit of the novel approach
Contributions to the Power Spectrum of Cosmic Microwave Background from Fluctuations Caused by Clusters of Galaxies
We estimate the contributions to the cosmic microwave background radiation
(CMBR) power spectrum from the static and kinematic Sunyaev-Zel'dovich (SZ)
effects, and from the moving cluster of galaxies (MCG) effect. We conclude, in
agreement with other studies, that at sufficiently small scales secondary
fluctuations caused by clusters provide important contributions to the CMBR. At
, these secondary fluctuations become important relative to
lensed primordial fluctuations. Gravitational lensing at small angular scales
has been proposed as a way to break the ``geometric degeneracy'' in determining
fundamental cosmological parameters. We show that this method requires the
separation of the static SZ effect, but the kinematic SZ effect and the MCG
effect are less important. The power spectrum of secondary fluctuations caused
by clusters of galaxies, if separated from the spectrum of lensed primordial
fluctuations, might provide an independent constraint on several important
cosmological parameters.Comment: LateX, 41 pages and 10 figures. Accepted for publication in the
Astrophysical Journa
A review of research into business coaching supervision
A systematic search of the coaching literature for original peer-reviewed studies into business coaching supervision yielded seven research reports. Evaluation of these studies showed them to be low in the reporting of methodological rigour. However, as an emerging area of research with great importance for the development of the profession of business coaching these studies provide valuable insights into the functions of supervision and its benefits. Gaps in knowledge and directions for future research are identified. There is a need for future research to be more rigorous in its reporting of methods and analytic procedures, small scale qualitative research that can provide insight into the issues and challenges of coaching supervision in specific contexts, and large scale quantitative research which can provide broader and generalizable understandings into the uses and benefits of supervision
The Abnormally Weighting Energy Hypothesis: the Missing Link between Dark Matter and Dark Energy
We generalize tensor-scalar theories of gravitation by the introduction of an
abnormally weighting type of energy. This theory of tensor-scalar anomalous
gravity is based on a relaxation of the weak equivalence principle that is now
restricted to ordinary visible matter only. As a consequence, the convergence
mechanism toward general relativity is modified and produces naturally cosmic
acceleration as an inescapable gravitational feedback induced by the
mass-variation of some invisible sector. The cosmological implications of this
new theoretical framework are studied. From the Hubble diagram cosmological
test \textit{alone}, this theory provides an estimation of the amount of
baryons and dark matter in the Universe that is consistent with the independent
cosmological tests of Cosmic Microwave Background (CMB) and Big Bang
Nucleosynthesis (BBN). Cosmic coincidence is naturally achieved from a equally
natural assumption on the amplitude of the scalar coupling strength. Finally,
from the adequacy to supernovae data, we derive a new intriguing relation
between the space-time dependences of the gravitational coupling and the dark
matter mass, providing an example of crucial constraint on microphysics from
cosmology. This glimpses at an enticing new symmetry between the visible and
invisible sectors, namely that the scalar charges of visible and invisible
matter are exactly opposite.Comment: 24 pages, 6 figures, new version with extended discussions and added
references. Accepted for publication in JCAP (sept. 2008
Target mass number dependence of subthreshold antiproton production in proton-, deuteron- and alpha-particle-induced reactions
Data from KEK on subthreshold \bar{\mrm{p}} as well as on and
\mrm{K}^\pm production in proton-, deuteron- and -induced reactions
at energies between 2.0 and 12.0 A GeV for C, Cu and Pb targets are described
within a unified approach. We use a model which considers a nuclear reaction as
an incoherent sum over collisions of varying numbers of projectile and target
nucleons. It samples complete events and thus allows for the simultaneous
consideration of all final particles including the decay products of the
nuclear residues. The enormous enhancement of the \bar{\mrm{p}} cross
section, as well as the moderate increase of meson production in deuteron and
induced compared to proton-induced reactions, is well reproduced for
all target nuclei. In our approach, the observed enhancement near the
production threshold is mainly due to the contributions from the interactions
of few-nucleon clusters by simultaneously considering fragmentation processes
of the nuclear residues. The ability of the model to reproduce the target mass
dependence may be considered as a further proof of the validity of the cluster
concept.Comment: 9 pages, 4 figure
Phenomenological analysis of K+ meson production in proton-nucleus collisions
Total and differential cross sections from literature, on the production of
K+ mesons in pA interactions at projectile energies between T=0.8 and 2.9 GeV,
covering the transition across the free nucleon-nucleon threshold at 1.58 GeV,
have been investigated. From the target-mass dependence of the production cross
sections no evidence for the expected change of the dominant reaction mechanism
from two-step to direct kaon production was found. At T=1.0 GeV the A
dependences of the total cross sections and of the most recent data from
COSY-Juelich, differential cross sections measured under forward angles, are
strongly different. The invariant K+ production cross sections show an overall
exponential scaling behavior with the squared four-momentum transfer between
the beam proton and the produced K+ meson for t< -0.05 GeV^2 independent of the
beam energy and emission angle. The data from COSY-Juelich reveal a strongly
different t dependence in the region of t>0 GeV^2. Further data at forward
angles and different beam energies should be taken in order to explore this
region of kinematically extreme conditions.Comment: 9 Pages, 11 Figure
Inflationary attractor in Gauss-Bonnet brane cosmology
The inflationary attractor properties of the canonical scalar field and
Born-Infeld field are investigated in the Randall-Sundrum II scenario with a
Gauss-Bonnet term in the bulk action. We find that the inflationary attractor
property will always hold for both the canonical and Born-Infeld fields for any
allowed non-negative Gauss-Bonnet coupling. We also briefly discuss the
possibility of explaining the suppressed lower multiples and running scalar
spectral index simultaneously in the scenario of Gauss-Bonnet brane inflation.Comment: 7 pages, no figures. An error in the discussion of BI field
corrected, conclusion correcte
Coupled Maps on Trees
We study coupled maps on a Cayley tree, with local (nearest-neighbor)
interactions, and with a variety of boundary conditions. The homogeneous state
(where every lattice site has the same value) and the node-synchronized state
(where sites of a given generation have the same value) are both shown to occur
for particular values of the parameters and coupling constants. We study the
stability of these states and their domains of attraction. As the number of
sites that become synchronized is much higher compared to that on a regular
lattice, control is easier to effect. A general procedure is given to deduce
the eigenvalue spectrum for these states. Perturbations of the synchronized
state lead to different spatio-temporal structures. We find that a mean-field
like treatment is valid on this (effectively infinite dimensional) lattice.Comment: latex file (25 pages), 4 figures included. To be published in Phys.
Rev.
Modelling Clock Synchronization in the Chess gMAC WSN Protocol
We present a detailled timed automata model of the clock synchronization
algorithm that is currently being used in a wireless sensor network (WSN) that
has been developed by the Dutch company Chess. Using the Uppaal model checker,
we establish that in certain cases a static, fully synchronized network may
eventually become unsynchronized if the current algorithm is used, even in a
setting with infinitesimal clock drifts
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