458 research outputs found
A TBLMI Framework for Harmonic Robust Control
The primary objective of this paper is to demonstrate that problems related
to stability and robust control in the harmonic context can be effectively
addressed by formulating them as semidefinite optimization problems, invoking
the concept of infinite-dimensional Toeplitz Block LMIs (TBLMIs). One of the
central challenges tackled in this study pertains to the efficient resolution
of these infinite-dimensional TBLMIs. Exploiting the structured nature of such
problems, we introduce a consistent truncation method that effectively reduces
the problem to a finite-dimensional convex optimization problem. By consistent
we mean that the solution to this finite-dimensional problem allows to closely
approximate the infinite-dimensional solution with arbitrary precision.
Furthermore, we establish a link between the harmonic framework and the time
domain setting, emphasizing the advantages over Periodic Differential LMIs
(PDLMIs). We illustrate that our proposed framework is not only theoretically
sound but also practically applicable to solving H 2 and H harmonic
control design problems. To enable this, we extend the definitions of H 2 and
H norms into the harmonic space, leveraging the concepts of the
harmonic transfer function and the average trace operator for Toeplitz Block
operators. Throughout this paper, we support our theoretical contributions with
a range of illustrative examples that demonstrate the effectiveness of our
approach
Modelling the Influence of Landscape Management Practices on the Hydrology of a Small Agricultural Catchment
Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv
A harmonic framework for the identification of linear time-periodic systems
This paper presents a novel approach for the identification of linear
time-periodic (LTP) systems in continuous time. This method is based on
harmonic modeling and consists in converting any LTP system into an equivalent
LTI system with infinite dimension. Leveraging specific harmonic properties, we
demonstrate that solving this infinite-dimensional identification problem can
be reduced to solving a finitedimensional linear least-squares problem. The
result is an approximation of the original solution with an arbitrarily small
error. Our approach offers several significant advantages. The first one is
closely tied to the harmonic system's inherent LTI characteristic, along with
the Toeplitz structure exhibited by its elements. The second advantage is
related to the regularization property achieved through the integral action
when computing the phasors from input and state trajectories. Finally, our
method avoids the computation of signals' derivative. This sets our approach
apart from existing methods that rely on such computations, which can be a
notable drawback, especially in continuous-time settings. We provide numerical
simulations that convincingly demonstrate the effectiveness of the proposed
method, even in scenarios where signals are corrupted by noise
Knowledge Gaps and Emerging Research Areas in Intrauterine Growth Restriction-Associated Brain Injury
Intrauterine growth restriction (IUGR) is a complex global healthcare issue. Concerted research and clinical efforts have improved our knowledge of the neurodevelopmental sequelae of IUGR which has raised the profile of this complex problem. Nevertheless, there is still a lack of therapies to prevent the substantial rates of fetal demise or the constellation of permanent neurological deficits that arise from IUGR. The purpose of this article is to highlight the clinical and translational gaps in our knowledge that hamper our collective efforts to improve the neurological sequelae of IUGR. Also, we draw attention to cutting-edge tools and techniques that can provide novel insights into this disorder, and technologies that offer the potential for better drug design and delivery. We cover topics including: how we can improve our use of crib-side monitoring options, what we still need to know about inflammation in IUGR, the necessity for more human post-mortem studies, lessons from improved integrated histology-imaging analyses regarding the cell-specific nature of magnetic resonance imaging (MRI) signals, options to improve risk stratification with genomic analysis, and treatments mediated by nanoparticle delivery which are designed to modify specific cell functions
Niche divergence corresponds to genetic differentiation within the parrot-beaked tortoise Homopus areolatus (Reptilia: Testudinidae), endemic to South Africa
We assessed genetic differentiation and habitat suitability for Homopus areolatus during current and Last Glacial
Maximum (LGM) conditions. The ND4 locus retrieved two monophyletic mtDNA clades with lower diversity in clade 1, in the west, than in clade 2, in the south-east. Clade 1 showed a north–south and clade 2 a west-to-east genetic divergence, and the clades co-occur in the syntaxis zone of the Cape Fold Mountains. The clades occupy distinct niches with limited overlap. Rainfall seasonality contributed most to habitat suitability, with clade 1 being restricted to winter rainfall and clade 2 to all-year rainfall regions. Precipitation variables contributed 90% and 60%, respectively, to habitat suitability of clades 1 and 2, with temperature, particularly mean temperature of the driest quarter, being= of greater importance for clade 2 than clade 1. Suitable habitat shrank from the LGM to current conditions, probably due to reduced rainfall in the west and higher temperatures in most regions. We conclude that patterns of genetic divergence are strongly associated with ecological niche divergence of H. areolatus clades. More studies are needed to assess the taxonomic status of clade 1, particularly in view of its shrinking habitat due to climate change and anthropogenic factors
Réalisation d’un Contrat d’Etudes Prospectives des secteurs du transport: Rapport final
Le CEP a pour objectif de réaliser un état des lieux du secteur, de conduire une analyse prospective qualitative et quantitative de l’évolution des métiers et des besoins de compétences du transport et de préconiser un plan d’actions pour les transports routiers, maritimes et fluviaux. A l’issue des travaux d’étude, le rapport final a été remis aux membres du Comité de pilotage (Ministère de l’emploi - DGEFP, Représentants des branches des transports, l’OPCA Transports et Services, Pôle Emploi, Ministère de l’écologie et du développement durable, des transport et du logement)
Guidelines for the good practice of surface wave analysis: a product of the InterPACIFIC project
Surface wave methods gained in the past decades a primary role in many seismic
projects. Specifically, they are often used to retrieve a 1D shear wave velocity model or to
estimate the VS,30 at a site. The complexity of the interpretation process and the variety of
possible approaches to surface wave analysis make it very hard to set a fixed standard to
assure quality and reliability of the results. The present guidelines provide practical information on the acquisition and analysis of surface wave data by giving some basic
principles and specific suggestions related to the most common situations. They are primarily
targeted to non-expert users approaching surface wave testing, but can be useful to
specialists in the field as a general reference. The guidelines are based on the experience
gained within the InterPACIFIC project and on the expertise of the participants in
acquisition and analysis of surface wave data.Published2367-24205T. Sismologia, geofisica e geologia per l'ingegneria sismicaJCR Journa
Estimativa da altura dominante em povoamentos decÃduos através de dados LIDAR com múltiplos retornosEstimating dominant height in deciduous stands using multi-echo LIDAR data
A altura dominante (Ho) de 120 parcelas georreferenciadas (600m² cada) foi estimada através de diversas medidas de distribuição, máximas locais e densidade derivada da varredura a laser com pequena impressão obtida em um povoamento florestal decÃduo irregular. As parcelas foram distribuÃdas de forma a contemplar toda a variabilidade de alturas dominantes e o tipo de regeneração existente nos 112km² da área estudada, localizada na floresta de Haye, França. O modelo construÃdo com variáveis de máxima local (Hmv5) e densidade de retornos (d9) foi capaz de estimar a Ho com alta acurácia, além de ser independente do tipo de povoamento, o que possibilitou sua aplicação em toda a floresta. A validação cruzada do modelo final mostrou que este explicou 98% da variabilidade observada nas parcelas em campo, com um RMSE de 0.77m (3.31%). Nenhum efeito drástico da escolha do MNT, densidade de retornos ou do posicionamento das parcelas foi detectado no modelo, sugerindo grande estabilidade. AbstractThe mean dominant heights of 120 georeferenced field sample plots (600m² each) were estimated from a range of canopy densities, distributions and local maxima metrics derived by a small-footprint laser scanner over various deciduous forest stands using regression analysis. The sample plots were distributed in order to better represent the variability in stand dominant height and regeneration practices throughout a 112km² study areas in Haye forest, France. The model constructed with local maxima (Hmv5) and a LIDAR density metric (d9) was able to estimate Ho with a very high accuracy and was not sensitive to stand types. Cross-validation showed that the final model explained 98% of the variability in ground-truth dominant height, with a RMSE of 0.77m (3.31%). No drastic effects of DTM, echo densities, or positioning errors were found in the models
Changes in intraocular pressure and optic nerve sheath diameter in patients undergoing robotic-assisted laparoscopic prostatectomyin steep 45 degree Trendelenburg position
Background: To evaluate changes in intraocular pressure (IOP) and intracerebral pressure (ICP) reflected by the optic nerve sheath diameter (ONSD) in patients undergoing robotic-assisted laparoscopic prostatectomy (RALP) in permanent 45 degrees steep Trendelenburg position (STP). Methods: Fifty-one patients undergoing RALP under a standardised anaesthesia. IOP was perioperatively measured in awake patients (T0) and IOP and ONSD 20 min after induction of anaesthesia (T1), after insufflation of the abdomen in supine position (T2), after 30 min in STP (T3), when controlling Santorini's plexus in STP (T4) and before awakening while supine (T5). We investigated the influence of respiratory and circulatory parameters as well as patient-specific and time-dependent factors on IOP and ONSD. Results: Average IOP values (mmHg) were T0 = 19.9, T1 = 15.9, T2 = 20.1, T3 = 30.7, T4 = 33.9 and T5 = 21.8. IOP was 14. 0 +/- 7.47 mmHg (mean +/- SD) higher at T4 than T0 (p = 0.013). Univariate mixed effects models showed peak inspiratory pressure (PIP) and mean arterial blood pressure (MAP) to be significant predictors for IOP increase. Mean ONSD values (mm) were T1 = 5.88, T2 = 6.08, T3 = 6.07, T4 = 6.04 and T5 = 5.96. The ONSD remained permanently > 6.0 mm during RALP. Patients aged < 63 years showed a 0.21 mm wider ONSD on average (p = 0.017) and greater variations in diameter than older patients. Conclusions: The combination of STP and capnoperitoneum during RALP has a pronounced influence on IOP and, to a lesser degree, on ICP. IOP is directly correlated with increasing PIP and MAP. IOP doubled and the ONSD rose to values indicating increased intracranial pressure. Differences in the ONSD were age-related, showing higher output values as well as better autoregulation and compliance in STP for patients aged < 63 years. Despite several ocular changes during RALP, visual function was not significantly impaired postoperatively
Ancient DNA elucidates the lost world of western Indian Ocean giant tortoises and reveals a new extinct species from Madagascar
© 2023 The Authors. Published by the American Association for the Advancement of Science under a Creative Commons License. The published version can be accessed at the following link on the publisher’s website: https://www.science.org/doi/10.1126/sciadv.abq2574Before humans arrived, giant tortoises occurred on many western Indian Ocean islands. We combined ancient DNA, phylogenetic, ancestral range, and molecular clock analyses with radiocarbon and paleogeographic evidence to decipher their diversity and biogeography. Using a mitogenomic time tree, we propose that the ancestor of the extinct Mascarene tortoises spread from Africa in the Eocene to now-sunken islands northeast of Madagascar. From these islands, the Mascarenes were repeatedly colonized. Another out-of-Africa dispersal (latest Eocene/Oligocene) produced on Madagascar giant, large, and small tortoise species. Two giant and one large species disappeared c. 1000 to 600 years ago, the latter described here as new to science using nuclear and mitochondrial DNA. From Madagascar, the Granitic Seychelles were colonized (Early Pliocene) and from there, repeatedly Aldabra (Late Pleistocene). The Granitic Seychelles populations were eradicated and later reintroduced from Aldabra. Our results underline that integrating ancient DNA data into a multi-evidence framework substantially enhances the knowledge of the past diversity of island faunas.The work of C.K. and U.F. was supported by the Senckenberg Society for Nature Research (SGN), Germany. The work of E.G. and U.F. was partially supported by the Spanish Ministry of Science and Innovation through the project PID2019-105682RA-100/AEI/10.13039/501100011033. The work of V.D. was supported by the Alexander von Humboldt Foundation, Germany. F.I. was supported by the German Research Foundation (DFG, grant number IH 133/1-1).Published versio
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