2022
Authors
Bond, CZ; Sauvage, JF; Schwartz, N; Levraud, N; Chambouleyron, V; Correia, C; Fusco, T; Neichel, B;
Publication
ADAPTIVE OPTICS SYSTEMS VIII
Abstract
HARMONI is the first light visible and near-IR integral field spectrograph for the ELT. It covers a large spectral range from 450nm to 2450nm with resolving powers from 3500 to 18000 and spatial sampling from 60mas to 4mas. It can operate in two Adaptive Optics (AO) modes - SCAO (including a High Contrast capability) and LTAO - or with NOAO. The project is preparing for Final Design Reviews. The SCAO system for HARMONI is based on a pyramid wavefront sensor (PWFS) operating in the visible (700 - 1000 nm). Previous implementations on very large telescopes have demonstrated the challenges associated with optimising PWFS performance on-sky, particularly when operated at visible wavelengths. ELT operation will pose further challenges for AO systems, particularly related to the segmentation of the telescope and the control of badly seen 'etal modes'. In this paper we investigate these challenges in the context of the HARMONI SCAO system. We present the results of end-to-end simulations of our baseline approach, using a coupled control basis to avoid the runaway development of petal modes in the control loop. The impact of key parameters are investigated and methods for optical gain compensation and optimisation of the control basis are presented. We discuss recent updates to the control algorithms and demonstrate the possibility of improving performance using a form of super resolution. Finally, we report on the expected performance across a range of conditions.
2022
Authors
Plantet, C; Neichel, B; Agapito, G; Busoni, L; Correia, CM; Fusco, T; Bonaglia, M; Esposito, S;
Publication
JOURNAL OF ASTRONOMICAL TELESCOPES INSTRUMENTS AND SYSTEMS
Abstract
The instruments developed for the upcoming Extremely Large Telescopes (ELTs) will need efficient adaptive optics (AO) systems to correct the effects of the atmospheric turbulence and allow imaging at the highest angular resolution. One of the most important requirements for ELT AO-assisted instruments will be to deliver diffraction-limited images in a significant part of the sky. For that, the instruments will be equipped with laser guide stars (LGSs) providing most of the information required by AO instruments. But even with LGSs, AO systems still require the use of natural guide stars (NGSs) to compensate for image motion (jitter) and some low order aberrations. These NGSs are eventually limiting the fraction of the sky that can be achieved by AO systems, the so-called sky coverage (SC). We first present the SC assessment methods used for high angular resolution monolithic optical and near-infrared integral field spectrograph (HARMONI) and multiconjugate adaptive optics relay/multi-AO imaging camera for deep observations (MAORY/MICADO), that are both instruments for the ELT of the European Southern Observatory (ESO). They are based on a semianalytical description of the main contributors in the AO error budget, allowing for a fast estimation of the residual jitter. As such, these methods are well suited for statistical estimation of the SC on multiple science fields and/or to efficiently explore the system parameter space. We then compute the SC of the two instruments in cosmological fields from the cosmic assembly near-IR deep extragalactic legacy survey catalog. The goal is to provide an insight on the possibilities given by two different types of tomographic AO systems, i.e., laser tomography AO with HARMONI and multiconjugate AO with MAORY, on the same telescope. In particular, we show that HARMONI and MAORY/MICADO are complementary, meaning that the overall SC of ESO's ELT is much improved for applications common to both systems. (C) The Authors. Published by SPIE under a Creative Commons Attribution 4.0 International License.
2022
Authors
Cardoso, VEM; Simoes, ML; Ramos, NMM; Almeida, RMSF; Almeida, M; Fernandes, JND;
Publication
ENERGY AND BUILDINGS
Abstract
Energy efficiency and indoor air quality are frequently-two conflicting objectives when establishing the air change rate (ACH) of a dwelling. In Europe, the northern countries have a clear focus on energy conservation, leading to an obvious awareness of the importance of airtightness, which translates into a high level of regulation and implementation. Meanwhile, the southern counterparts experience a more com-plex challenge by having predominantly passive ventilation strategies and milder climates, which often results in a more permissive approach. This work proposes an innovative labelling methodology to classify the performance of naturally ventilated dwellings. A representative sample of a southern European national built stock is used in a stochastic process to create a pool of 43,200 unique dwellings. The simulation period refers to a month of the typical heating season in the southern European mild conditions. The results test the labelling methodology. With feature selection, ACH limits, and a labelling strategy, dwellings classify according to their ability to provide adequate ACHs. The terrain was the best splitter of the dataset from the applied categorical variables. Regarding continuous variables, the airtightness was the one explaining most of the variability of the outputted ACHs, followed by the floor area. From the best performing dwellings labelled as compliant (Com), the average airtightness level was 5.3 h(-1), with 4.9 h(-1) and 5.8 h(-1) in rural and urban locations.
2022
Authors
Fernandes, JND; Matos, JC; Sousa, HS; Coelho, MRF;
Publication
ADVANCES IN CIVIL ENGINEERING
Abstract
In the context of bridge management, three main types of maintenance actions can be considered. Maintenance actions can be taken preventively before the predefined limit condition is reached, or as a corrective measure in case those limits have been reached. The third possibility corresponds to the so-called doing nothing scenario, in which no action is taken on the bridge. To be able to implement preventive maintenance, it is necessary to know the current condition of the bridge, as well as to be able to predict its performance. On the other hand, it is also important to be able to identify potentially threatening events that might occur in the analysis life period. This paper describes an integrated methodology to help bridge managers in defining an efficient maintenance program, considering the specific case of a railway bridge. The novelty of the methodology is focused on updating an existing methodology proposed by COST TU1406, by extending it to railway bridges and also by including the resilience analysis in case of a sudden event occurrence. The analysis considers a multi-hazard future scenario, in which a flood event occurs while corrosion phenomena were already in place. The results show the feasibility of the proposed methodology as a support for the establishment of an efficient maintenance schedule to prevent bridge severe degradation, as well as to establish recovery plans in case of a sudden event.
2022
Authors
Miller J.; Soltanaghai E.; Duvall R.; Chen J.; Bhat V.; Pereira N.; Rowe A.;
Publication
Proceedings - 21st ACM/IEEE International Conference on Information Processing in Sensor Networks, IPSN 2022
Abstract
Current collaborative augmented reality (AR) systems establish a common localization coordinate frame among users by exchanging and comparing maps comprised of feature points. However, relative positioning through map sharing struggles in dynamic or feature-sparse environments. It also requires that users exchange identical regions of the map, which may not be possible if they are separated by walls or facing different directions. In this paper, we present Cappella11Like its musical inspiration, Cappella utilizes collaboration among agents to forgo the need for instrumentation, an infrastructure-free 6-degrees-of-freedom (6DOF) positioning system for multi-user AR applications that uses motion estimates and range measurements between users to establish an accurate relative coordinate system. Cappella uses visual-inertial odometry (VIO) in conjunction with ultra-wideband (UWB) ranging radios to estimate the relative position of each device in an ad hoc manner. The system leverages a collaborative particle filtering formulation that operates on sporadic messages exchanged between nearby users. Unlike visual landmark sharing approaches, this allows for collaborative AR sessions even if users do not share the same field of view, or if the environment is too dynamic for feature matching to be reliable. We show that not only is it possible to perform collaborative positioning without infrastructure or global coordinates, but that our approach provides nearly the same level of accuracy as fixed infrastructure approaches for AR teaming applications. Cappella consists of an open source UWB firmware and reference mobile phone application that can display the location of team members in real time using mobile AR. We evaluate Cappella across mul-tiple buildings under a wide variety of conditions, including a contiguous 30,000 square foot region spanning multiple floors, and find that it achieves median geometric error in 3D of less than 1 meter.
2022
Authors
Martins, IS; Pinheiro, MR; Silva, HF; Tuchin, VV; Oliveira, LM;
Publication
2022 International Conference Laser Optics, ICLO 2022 - Proceedingss
Abstract
The evaluation of the diffusion properties of optical clearing agents in biological tissues, which are necessary to characterize the transparency mechanisms, has been traditionally made using ex vivo tissues. With the objective of performing such evaluation in vivo, this study was made to evaluate and compare those properties for propylene glycol in skeletal muscle, as obtained with the collimated transmittance and diffuse reflectance kinetics. The diffusion time and the diffusion coefficient of propylene glycol in the muscle that were calculated both from transmittance and reflectance kinetics presented a deviation of 0.8%, a result that opens the possibility to use such a method in vivo. © 2022 IEEE.
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