423 research outputs found
Optimal Sensing and Actuation Policies for Networked Mobile Agents in a Class of Cyber-Physical Systems
The main purpose of this dissertation is to define and solve problems on optimal sensing and actuating policies in Cyber-Physical Systems (CPSs). Cyber-physical system is a term that was introduced recently to define the increasing complexity of the interactions between computational hardwares and their physical environments. The problem of designing the ``cyber\u27\u27 part may not be trivial but can be solved from scratch. However, the ``physical\u27\u27 part, usually a natural physical process, is inherently given and has to be identified in order to propose an appropriate ``cyber\u27\u27 part to be adopted. Therefore, one of the first steps in designing a CPS is to identify its ``physical\u27\u27 part. The ``physical\u27\u27 part can belong to a large array of system classes. Among the possible candidates, we focus our interest on Distributed Parameter Systems (DPSs) whose dynamics can be modeled by Partial Differential Equations (PDE). DPSs are by nature very challenging to observe as their states are distributed throughout the spatial domain of interest. Therefore, systematic approaches have to be developed to obtain the optimal locations of sensors to optimally estimate the parameters of a given DPS. In this dissertation, we first review the recent methods from the literature as the foundations of our contributions. Then, we define new research problems within the above optimal parameter estimation framework. Two different yet important problems considered are the optimal mobile sensor trajectory planning and the accuracy effects and allocation of heterogeneous sensors. Under the remote sensing setting, we are able to determine the optimal trajectories of remote sensors. The problem of optimal robust estimation is then introduced and solved using an interlaced ``online\u27\u27 or ``real-time\u27\u27 scheme. Actuation policies are introduced into the framework to improve the estimation by providing the best stimulation of the DPS for optimal parameter identification, where trajectories of both sensors and actuators are optimized simultaneously. We also introduce a new methodology to solving fractional-order optimal control problems, with which we demonstrate that we can solve optimal sensing policy problems when sensors move in complex media, displaying fractional dynamics. We consider and solve the problem of optimal scale reconciliation using satellite imagery, ground measurements, and Unmanned Aerial Vehicles (UAV)-based personal remote sensing. Finally, to provide the reader with all the necessary background, the appendices contain important concepts and theorems from the literature as well as the Matlab codes used to numerically solve some of the described problems
Coastal Ocean Forecasting: science foundation and user benefits
The advancement of Coastal Ocean Forecasting Systems (COFS) requires the support of continuous scientific progress addressing: (a) the primary mechanisms driving coastal circulation; (b) methods to achieve fully integrated coastal systems (observations and models), that are dynamically embedded in larger scale systems; and (c) methods to adequately represent air-sea and biophysical interactions. Issues of downscaling, data assimilation, atmosphere-wave-ocean couplings and ecosystem dynamics in the coastal ocean are discussed. These science topics are fundamental for successful COFS, which are connected to evolving downstream applications, dictated by the socioeconomic needs of rapidly increasing coastal populations
Coastal high-frequency radars in the Mediterranean ??? Part 2: Applications in support of science priorities and societal needs
International audienceThe Mediterranean Sea is a prominent climate-change hot spot, with many socioeconomically vital coastal areas being the most vulnerable targets for maritime safety, diverse met-ocean hazards and marine pollution. Providing an unprecedented spatial and temporal resolution at wide coastal areas, high-frequency radars (HFRs) have been steadily gaining recognition as an effective land-based remote sensing technology for continuous monitoring of the surface circulation, increasingly waves and occasionally winds. HFR measurements have boosted the thorough scientific knowledge of coastal processes, also fostering a broad range of applications, which has promoted their integration in coastal ocean observing systems worldwide, with more than half of the European sites located in the Mediterranean coastal areas. In this work, we present a review of existing HFR data multidisciplinary science-based applications in the Mediterranean Sea, primarily focused on meeting end-user and science-driven requirements, addressing regional challenges in three main topics: (i) maritime safety, (ii) extreme hazards and (iii) environmental transport process. Additionally, the HFR observing and monitoring regional capabilities in the Mediterranean coastal areas required to underpin the underlying science and the further development of applications are also analyzed. The outcome of this assessment has allowed us to provide a set of recommendations for future improvement prospects to maximize the contribution to extending science-based HFR products into societally relevant downstream services to support blue growth in the Mediterranean coastal areas, helping to meet the UN's Decade of Ocean Science for Sustainable Development and the EU's Green Deal goals
Coastal high-frequency radars in the Mediterranean - Part 2: Applications in support of science priorities and societal needs
The Mediterranean Sea is a prominent climate-change hot spot, with many socioeconomically vital coastal areas being the most vulnerable targets for maritime safety, diverse met-ocean hazards and marine pollution. Providing an unprecedented spatial and temporal resolution at wide coastal areas, high-frequency radars (HFRs) have been steadily gaining recognition as an effective land-based remote sensing technology for continuous monitoring of the surface circulation, increasingly waves and occasionally winds. HFR measurements have boosted the thorough scientific knowledge of coastal processes, also fostering a broad range of applications, which has promoted their integration in coastal ocean observing systems worldwide, with more than half of the European sites located in the Mediterranean coastal areas. In this work, we present a review of existing HFR data multidisciplinary science-based applications in the Mediterranean Sea, primarily focused on meeting end-user and science-driven requirements, addressing regional challenges in three main topics: (i) maritime safety, (ii) extreme hazards and (iii) environmental transport process. Additionally, the HFR observing and monitoring regional capabilities in the Mediterranean coastal areas required to underpin the underlying science and the further development of applications are also analyzed. The outcome of this assessment has allowed us to provide a set of recommendations for future improvement prospects to maximize the contribution to extending science-based HFR products into societally relevant downstream services to support blue growth in the Mediterranean coastal areas, helping to meet the UN's Decade of Ocean Science for Sustainable Development and the EU's Green Deal goals
Proceedings Of The 18th Annual Meeting Of The Asia Oceania Geosciences Society (Aogs 2021)
The 18th Annual Meeting of the Asia Oceania Geosciences Society (AOGS 2021) was held from 1st to 6th August 2021. This proceedings volume includes selected extended abstracts from a challenging array of presentations at this conference. The AOGS Annual Meeting is a leading venue for professional interaction among researchers and practitioners, covering diverse disciplines of geosciences
The future of Earth observation in hydrology
In just the past 5 years, the field of Earth observation has progressed beyond the offerings of conventional space-agency-based platforms to include a plethora of sensing opportunities afforded by CubeSats, unmanned aerial vehicles (UAVs), and smartphone technologies that are being embraced by both for-profit companies and individual researchers. Over the previous decades, space agency efforts have brought forth well-known and immensely useful satellites such as the Landsat series and the Gravity Research and Climate Experiment (GRACE) system, with costs typically of the order of 1 billion dollars per satellite and with concept-to-launch timelines of the order of 2 decades (for new missions). More recently, the proliferation of smart-phones has helped to miniaturize sensors and energy requirements, facilitating advances in the use of CubeSats that can be launched by the dozens, while providing ultra-high (3-5 m) resolution sensing of the Earth on a daily basis. Start-up companies that did not exist a decade ago now operate more satellites in orbit than any space agency, and at costs that are a mere fraction of traditional satellite missions. With these advances come new space-borne measurements, such as real-time high-definition video for tracking air pollution, storm-cell development, flood propagation, precipitation monitoring, or even for constructing digital surfaces using structure-from-motion techniques. Closer to the surface, measurements from small unmanned drones and tethered balloons have mapped snow depths, floods, and estimated evaporation at sub-metre resolutions, pushing back on spatio-temporal constraints and delivering new process insights. At ground level, precipitation has been measured using signal attenuation between antennae mounted on cell phone towers, while the proliferation of mobile devices has enabled citizen scientists to catalogue photos of environmental conditions, estimate daily average temperatures from battery state, and sense other hydrologically important variables such as channel depths using commercially available wireless devices. Global internet access is being pursued via high-altitude balloons, solar planes, and hundreds of planned satellite launches, providing a means to exploit the "internet of things" as an entirely new measurement domain. Such global access will enable real-time collection of data from billions of smartphones or from remote research platforms. This future will produce petabytes of data that can only be accessed via cloud storage and will require new analytical approaches to interpret. The extent to which today's hydrologic models can usefully ingest such massive data volumes is unclear. Nor is it clear whether this deluge of data will be usefully exploited, either because the measurements are superfluous, inconsistent, not accurate enough, or simply because we lack the capacity to process and analyse them. What is apparent is that the tools and techniques afforded by this array of novel and game-changing sensing platforms present our community with a unique opportunity to develop new insights that advance fundamental aspects of the hydrological sciences. To accomplish this will require more than just an application of the technology: in some cases, it will demand a radical rethink on how we utilize and exploit these new observing systems
MOSAiC Implementation Plan
This document is the second version of the Implementation Plan for the Multidisciplinary drifting Observatory for the
Study of Arctic Climate (MOSAiC) initiative and lays out a vision of how associated observational, modeling, synthesis,
and programmatic objectives can be manifested. The document was drafted during an international workshop in
Potsdam in July 2015, and further developed during two additional workshops at AWI Potsdam in December 2015 and
February 2016. Support for this planning activity has been provided by the IASC-ICARPIII process, the Alfred Wegener
Institute Helmholtz Centre for Polar- and Marine Research, and the University of Colorado/ NOAA-ESRL-PSD. This
document provides a framework for planning the logistics of the project, developing scientific observing teams,
organizing scientific contributions, coordinating the use of resources, and ensuring MOSAiC’s legacy of data and
products. A brief overview and summaries of key science questions are provided in Section 1. Section 2 includes an
overview of specific observational requirements, while Section 3 describes the coordination and design of specific
field assets. Practical logistics plans are outlined in Section 4. Links with current and future satellite programs and
model activities are given in Sections 5 and 6. The MOSAiC data management strategy is given in Section 7. Links to
other programs are outlined in Section 8. The appendix (Section 9) lists the parameters to be measured and the
participating groups
Development of an operational tool for oil spill forecast: application to oil exposed regions
Tese de doutoramento, Ciências do Mar, da Terra e do Ambiente (Modelação), Faculdade de Ciências e Tecnologia, Universidade do Algarve, 2014The
objective
of
the
following
thesis
is
to
present
a
modelling
methodology,
based
on
the
MOHID
system,
which
allows
the
development
of
coastal
operational
models
by
taking
advantage
of
already
implemented
regional
operational
models
using
a
downscaling
approach.
This
increase
in
resolution
allows
studying
the
influence
of
coastal
scale
processes
in
the
dynamics
of
oil
spills,
while
contributing
to
more
accurate
forecasts.
The
methodology
was
used
to
forecast
the
evolution
of
oil
spills
in
two
distinct
areas
both
prone
to
oil
pollution
events:
Southwest
Portuguese
Coast
and
the
Tuscany
Archipelago
(Italy).
In
both
regions
an
operational
model
was
developed
and
validated
to
a
good
level,
using
several
types
of
oceanographic
data
available
in
European
and
global
databases.
The
method
was
tested
during
the
Costa
Concordia
accident,
where
operational
forecasts
aided
the
Italian
authorities
during
the
fuel
removal
operations.
Also
considered
in
this
work
are
the
interaction
between
waves/currents/wind
in
the
dynamics
of
oil
spills
at
sea,
the
identification
of
mesoscale
circulation
patterns
and
their
influence
on
the
risk
to
accidents
as
well
as
the
integration
of
these
numeric
methods
with
early
detection
and
monitoring
systems.O
objectivo
da
presente
tese
é
apresentar
uma
metodologia
de
modelação,
com
base
no
sistema
MOHID,
que
permite
criar
de
forma
robusta
e
expedita
modelos
operacionais
costeiros
tirando
partido
de
modelos
operacionais
regionais
já
existentes
numa
abordagem
de
malhas
encaixadas.
Isto
permite
aumentar
a
resolução
à
escala
costeira,
conseguindo
um
estudo
mais
aprofundado
da
influência
dos
vários
tipos
de
processos
costeiros
na
dinâmica
de
derrames,
ao
mesmo
tempo
melhorando
as
previsões
fornecidas.
Esta
metodologia
foi
usada
para
a
previsão
da
evolução
de
manchas
de
hidrocarbonetos
em
duas
zonas
consideradas
propensas
a
este
tipo
de
poluição:
Costa
Sudoeste
Portuguesa
e
o
Arquipélago
Toscano
(Itália).
Em
ambos
os
casos
de
estudo
os
modelos
operacionais
implementados
foram
validados
a
um
bom
nível,
utilizando
vários
tipos
de
dados
oceanográficos
disponíveis
em
bases
de
dados
europeias
e
globais.
A
robustez
do
método
foi
testada
durante
as
operações
de
retirada
de
combustível
do
navio
Costa
Concordia,
para
as
quais
o
sistema
forneceu
previsões
às
autoridades
Italianas.
São
ainda
considerados
na
presente
tese
a
interação
entre
ondas/correntes/vento
na
dinâmica
das
manchas
de
hidrocarbonetos
no
mar,
a
detecção
de
padrões
de
circulação
de
mesoescala
e
sua
influência
no
risco
a
acidentes,
bem
como
a
integração
destes
métodos
numéricos
com
sistemas
de
detecção
e
monitorização.Fundação para a Ciência e TecnologiaUniversidade do Algarv
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