11,221 research outputs found
On Galois-Division Multiple Access Systems: Figures of Merit and Performance Evaluation
A new approach to multiple access based on finite field transforms is
investigated. These schemes, termed Galois-Division Multiple Access (GDMA),
offer compact bandwidth requirements. A new digital transform, the Finite Field
Hartley Transform (FFHT) requires to deal with fields of characteristic p, p
\neq 2. A binary-to-p-ary (p \neq 2) mapping based on the opportunistic
secondary channel is introduced. This allows the use of GDMA in conjunction
with available digital systems. The performance of GDMA is also evaluated.Comment: 6 pages, 4 figures. In: XIX Simposio Brasileiro de Telecomunicacoes,
2001, Fortaleza, CE, Brazi
Meio ambiente baliza atuação da unidade a partir dos anos 90.
Projeto:11.11.11.111
Delimitação e caracterização preliminar da Área de Proteção Ambiental do Camanducaia (SP/MG).
Este trabalho apresenta uma contribuição do geoprocessamento para a implantação da Área de Proteção Ambiental do Camanducaia (SP/MG). Através da combinação de técnicas de sensoriamento remoto, sistemas de informações geográficas e reconhecimentos em campo, foram produzidas informações georreferenciadas sobre a área e operacionalizada uma base cartográfica digital atualizada. Os resultados incluem a delimitação e descrição detalhada dos limites da APA e 10 mapas, na escala 1:250.000, sobre os principais componentes da paisagem da área
Datasets of Fire and Crime Incidents in Pampanga, Philippines
The fire and crime incident datasets were requested and collected from two
Philippine regional agencies (i.e., the Bureau of Fire Protection and the
Philippine National Police). The datasets were used to initially analyze and
map both fire and crime incidents within the province of Pampanga for a
specific time frame. Several data preparation, normalization, and data cleaning
steps were implemented to properly map and identify patterns within the
datasets. The initial results also indicate the leading causes of fire and
crimes are rubbish and acts against property. Fires mostly occur during the dry
season in the province. Crime is particularly high during December, and most of
the fire and crime incidents occur during the time when people are most active.
The dataset was able to present the temporal characteristics of the fire and
crime incidents that occurred in the province of Pampanga. Merge the existing
dataset with the other datasets from other related agencies to get a bigger
picture and produce more objective results that could be used for
decision-making.Comment: 10 pages, 10 citations, 5 figures, 1 table, journal article,
peer-reviewe
Extra polarization states of cosmological gravitational waves in alternative theories of gravity
Cosmological Gravitational Waves (GWs) are usually associated with the
transverse-traceless part of the metric perturbations in the context of the
theory of cosmological perturbations. These modes are just the usual
polarizations `+' and `x' which appear in the general relativity theory.
However, in the majority of the alternative theories of gravity, GWs can
present more than these two polarization states. In this context, the
Newman-Penrose formalism is particularly suitable for evaluating the number of
non-null GW modes. In the present work we intend to take into account these
extra polarization states for cosmological GWs in alternative theories of
gravity. As an application, we derive the dynamical equations for cosmological
GWs for two specific theories, namely, a general scalar-tensor theory which
presents four polarization states and a massive bimetric theory which is in the
most general case with six polarization states for GWs. The mathematical tool
presented here is quite general, so it can be used to study cosmological
perturbations in all metric theories of gravity.Comment: 26 pages, 1 figure. Accepted for publication in Classical and Quantum
Gravity
Symmetry breaking effects upon bipartite and multipartite entanglement in the XY model
We analyze the bipartite and multipartite entanglement for the ground state
of the one-dimensional XY model in a transverse magnetic field in the
thermodynamical limit. We explicitly take into account the spontaneous symmetry
breaking in order to explore the relation between entanglement and quantum
phase transitions. As a result we show that while both bipartite and
multipartite entanglement can be enhanced by spontaneous symmetry breaking deep
into the ferromagnetic phase, only the latter is affected by it in the vicinity
of the critical point. This result adds to the evidence that multipartite, and
not bipartite, entanglement is the fundamental indicator of long range
correlations in quantum phase transitions.Comment: 13 pages, 19 figures, comments welcome. V2: small changes, published
versio
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