108 research outputs found
WALLSY: The UWB and SmartMesh IP enabled Wireless Ad-hoc Low-power Localization SYstem
This paper follows the implementation of a proofof-concept localization system for GNSS-denied environments.
WALLSY (Wireless Ad-hoc Low-power Localization SYstem)
is a portable and modular Ultra Wide-Band (UWB) and Smart
Mesh IP (SMIP) hybrid. WALLSY uses UWB two way ranging
(TWR) to measure distances, which are then sent via the lowpower SMIP backbone network to a central hub for calculating
coordinates of tracked objects. The system is highly flexible and
requires no external infrastructure or prior knowledge of the
installation site. It uses a completely nomadic topology and
delivers high localization accuracy with all modules being
battery powered. It achieves this by using a custom time-slotting
protocol which maximizes deep-sleep mode for UWB. Battery
life can be further improved by activating inertial measurement
unit (IMU) filtering. Visualization of tracked objects and
system reconfiguration can be executed on-the-fly and are both
accessible to end users through a simple graphical user interface
(GUI). Results demonstrate that WALLSY can achieve more
than ten times longer battery lifetime compared to competing
solutions (localizing every 30 seconds). It provides 3D
coordinates with an average spatial error of 60.5cm and an
average standard deviation of 15cm. The system also provides
support for up to 20 tags
How useful are equality indicators? The expressive function of ‘stat imperfecta’ in disability rights advocacy
Background: The measurement of equality is often difficult for groups who are weakly defined or poorly represented in official datasets. Social statistics are an essential component in rights recognition and advocacy because they make protected groups of persons visible and reveal the extent of their inequalities in comparison with population norms.
Aims and objectives: This paper examines how disabled persons have been included, or not, in EU statistics used for evidenced-based policy ‐ for example in the European Semester process concerning Member States’ employment and social policies, or in monitoring compliance with international human rights standards under the UN CRPD.
Methods: Over a period of a decade we mapped and disaggregated disability data from the main European social surveys, examining the availability and limitations of different sources to answer various policy questions.
Findings: The analysis produced indicators revealing stark inequalities between disabled and non-disabled persons but raised challenging questions about data quality, reliability and comparability. This revealed tensions in engaging the trust of policymakers in less familiar, or less reliable, data concerning minority groups.
Discussion and conclusions: Despite limitations of precision, imperfect statistics often retain a strong expressive function in human rights promotion. Greater investment is needed from governments and statistical authorities to strengthen disability equality data and indicators concerning marginalised rights holders
Exploring the synergy between promoting active participation in work and in society and social, health and long-term care strategies
The purpose of this study is to provide information that can help the Commission and EU Member
States engage in policy discussion on how social, health and long-term care systems can help enhance
participation in work and family, social and community activities and how, in turn, participation in
paid employment, family, social and community activities can contribute to healthy and autonomous
living at present and in the future.
Part I presents a review of the literature on the synergy between health and activity/work. Health
affects work and social participation but on the other side work and activity affect health. We focus on
people aged 55 and over as this interrelation (double causality) seems to be significant for important
life events (retirement decision, social participation, etc.) of this age group.
Part II presents a quantitative analysis and tries to identify national specificities. It presents the lessons
which we can draw from European surveys. It presents a quantitative analysis based on the LFS, the
EU-SILC, the ECHP UDB and SHARE surveys.
The fourth step summarises national policies and gives a comparative analysis, while the fifth step
presents the best practices.
Finally, the last part summarises the main conclusions and the policy implications
Localization of Energy and Momentum in an Asymptotically Reissner-Nordstr\"om Non-singular Black Hole Space-time Geometry
The space-time geometry exterior to a new four-dimensional, spherically
symmetric and charged black hole solution that, through a coupling of general
relativity with a non-linear electrodynamics, is everywhere non-singular, for
small it behaves as a de Sitter metric, and asymptotically it behaves as
the Reissner-Nordstr\"{o}m metric, is considered in order to study the
energy-momentum localization. For the calculation of the energy and momentum
distributions, the Einstein, Landau-Lifshitz, Weinberg and M\o ller
energy-momentum complexes have been applied. The results obtained show that in
all prescriptions the energy depends on the mass of the black hole, the
charge , two parameters and ,
and on the radial coordinate . The calculations performed in each
prescription show that all the momenta vanish. Additionally, some limiting and
particular cases for and are studied, and a possible connection with
strong gravitational lensing and micro lensing is attempted.Comment: To appear in Univers
Energy and Momentum Distributions of the Magnetic Solution to (2+1) Einstein-Maxwell Gravity
We use Moeller's energy-momentum complex in order to explicitly evaluate the
energy and momentum density distributions associated with the three-dimensional
magnetic solution to the Einstein-Maxwell equations. The magnetic spacetime
under consideration is a one-parametric solution describing the distribution of
a radial magnetic field in a three-dimensional AdS background, and representing
the superposition of the magnetic field with a 2+1 Einstein static
gravitational field.Comment: LaTex, 13 pages; v2 clarifying comments and references added,
Conclusions improved, to appear in Mod. Phys. Lett.
A causal model of radiating stellar collapse
We find a simple exact model of radiating stellar collapse, with a shear-free
and non-accelerating interior matched to a Vaidya exterior. The heat flux is
subject to causal thermodynamics, leading to self-consistent determination of
the temperature . We solve for exactly when the mean collision time
is constant, and perturbatively in a more realistic case of variable
. Causal thermodynamics predicts temperature behaviour that can
differ significantly from the predictions of non-causal theory. In particular,
the causal theory gives a higher central temperature and greater temperature
gradient.Comment: Latex [ioplppt style] 9 pages; to appear Class. Quantum Gra
On the energy of charged black holes in generalized dilaton-axion gravity
In this paper we calculate the energy distribution of some charged black
holes in generalized dilaton-axion gravity. The solutions correspond to charged
black holes arising in a Kalb-Ramond-dilaton background and some existing
non-rotating black hole solutions are recovered in special cases. We focus our
study to asymptotically flat and asymptotically non-flat types of solutions and
resort for this purpose to the M{\o}ller prescription. Various aspects of
energy are also analyzed.Comment: LaTe
Towards Canonical Quantum Gravity for G1 Geometries in 2+1 Dimensions with a Lambda--Term
The canonical analysis and subsequent quantization of the (2+1)-dimensional
action of pure gravity plus a cosmological constant term is considered, under
the assumption of the existence of one spacelike Killing vector field. The
proper imposition of the quantum analogues of the two linear (momentum)
constraints reduces an initial collection of state vectors, consisting of all
smooth functionals of the components (and/or their derivatives) of the spatial
metric, to particular scalar smooth functionals. The demand that the
midi-superspace metric (inferred from the kinetic part of the quadratic
(Hamiltonian) constraint) must define on the space of these states an induced
metric whose components are given in terms of the same states, which is made
possible through an appropriate re-normalization assumption, severely reduces
the possible state vectors to three unique (up to general coordinate
transformations) smooth scalar functionals. The quantum analogue of the
Hamiltonian constraint produces a Wheeler-DeWitt equation based on this reduced
manifold of states, which is completely integrated.Comment: Latex 2e source file, 25 pages, no figures, final version (accepted
in CQG
Combatting disability discrimination: a comparison of France and Great Britain
This article examines disabled people’s employment in Great Britain and France. Although both countries have poor rates of employment for disabled people compared to non-disabled people, Great Britain’s disabled people’s employment rate is lower than France’s. Possible explanations include weak enforcement mechanisms in Great Britain, British judicial resistance, the lack of an institutional role for British trade unions resulting in an implementation gap and the proactive form of French law, a quota-levy scheme, which has no British parallel. The conclusions suggest which of these explanations are the most plausible and propose that Great Britain considers adopting some French provisions, thus tempering Britain’s voluntarist approach
Distribution of Energy-Momentum in a Schwarzschild-Quintessence Space-time Geometry
An analysis of the energy-momentum localization for a four-dimensional\break
Schwarzschild black hole surrounded by quintessence is presented in order to
provide expressions for the distributions of energy and momentum. The
calculations are performed by using the Landau-Lifshitz and Weinberg
energy-momentum complexes. It is shown that all the momenta vanish, while the
expression for the energy depends on the mass of the black hole, the state
parameter and the normalization factor . The special case of
is also studied, and two limiting cases are examined.Comment: 9 page
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