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Publicações

2024

Characterizing indoor environmental quality in Portuguese office buildings for designing an intervention program

Autores
Felgueiras, F; Mourao, Z; Moreira, A; Gabriel, MF;

Publicação
BUILDING AND ENVIRONMENT

Abstract
Intervention studies have been explored to identify actions to effectively remediate indoor environmental quality (IEQ) problems and to improve people's health, well-being, comfort, and productivity. This study assessed a comprehensive set of IEQ indicators related to ventilation, air pollution, thermal comfort, illuminance, and noise for the first time in Portuguese office buildings. The purpose was to derive evidence-based corrective measures for a further environmental intervention program. The study monitored and surveyed 15 open-space offices from six modern office buildings in Porto (Portugal) during a workday between September and December 2022. Illuminance was of most concern among the assessed IEQ indicators since the measured levels were below the minimum limit required in 27% of the evaluated workplaces. For CO2, although mean concentrations were below 1000 ppm, absolute values exceeding that level were consistently registered in 20% of the offices during the afternoon period. Mean levels of PM2.5, PM10, and ultrafine particles exceeding the WHO guidelines were found in 13%, 7%, and 7% of the offices, respectively. The assessed thermal comfort levels were typically neutral, corresponding to an estimated mean of 6% of dissatisfied people. Based on the findings, an intervention plan was designed to be implemented in the further stages of this work. The priority interventions to test include relocation of printers (PM source removal), optimisation of ventilation rates (using real-time data from CO2 sensors), adjustment of desk positions to improve illuminance, and introduction of indoor plants.

2024

Autonomous Control and Positioning of a Mobile Radio Access Node Employing the O-RAN Architecture

Autores
Queirós, G; Correia, P; Coelho, A; Ricardo, M;

Publicação
2024 19TH WIRELESS ON-DEMAND NETWORK SYSTEMS AND SERVICES CONFERENCE, WONS

Abstract
Over the years, mobile networks were deployed using monolithic hardware based on proprietary solutions. Recently, the concept of open Radio Access Networks (RANs), including the standards and specifications from O-RAN Alliance, has emerged. It aims at enabling open, interoperable networks based on independent virtualized components connected through open interfaces. This paves the way to collect metrics and to control the RAN components by means of software applications such as the O-RAN-specified xApps. We propose a private standalone network leveraged by a mobile RAN employing the O-RAN architecture. The mobile RAN consists of a radio node (gNB) carried by a Mobile Robotic Platform autonomously positioned to provide on-demand wireless connectivity. The proposed solution employs a novel Mobility Management xApp to collect and process metrics from the RAN, while using an original algorithm to define the placement of the mobile RAN. This allows for the improvement of the connectivity offered to the User Equipments.

2024

Fusion of Time-of-Flight Based Sensors with Monocular Cameras for a Robotic Person Follower

Autores
Sarmento, J; dos Santos, FN; Aguiar, AS; Filipe, V; Valente, A;

Publicação
JOURNAL OF INTELLIGENT & ROBOTIC SYSTEMS

Abstract
Human-robot collaboration (HRC) is becoming increasingly important in advanced production systems, such as those used in industries and agriculture. This type of collaboration can contribute to productivity increase by reducing physical strain on humans, which can lead to reduced injuries and improved morale. One crucial aspect of HRC is the ability of the robot to follow a specific human operator safely. To address this challenge, a novel methodology is proposed that employs monocular vision and ultra-wideband (UWB) transceivers to determine the relative position of a human target with respect to the robot. UWB transceivers are capable of tracking humans with UWB transceivers but exhibit a significant angular error. To reduce this error, monocular cameras with Deep Learning object detection are used to detect humans. The reduction in angular error is achieved through sensor fusion, combining the outputs of both sensors using a histogram-based filter. This filter projects and intersects the measurements from both sources onto a 2D grid. By combining UWB and monocular vision, a remarkable 66.67% reduction in angular error compared to UWB localization alone is achieved. This approach demonstrates an average processing time of 0.0183s and an average localization error of 0.14 meters when tracking a person walking at an average speed of 0.21 m/s. This novel algorithm holds promise for enabling efficient and safe human-robot collaboration, providing a valuable contribution to the field of robotics.

2024

A longitudinal study of birth, death and survival rate of micro-companies in the European Union

Autores
Almeida, F;

Publicação
EUROPEAN JOURNAL OF INTERNATIONAL MANAGEMENT

Abstract
Micro-companies play an extremely important role in the economy being the main driver of economic growth. They contribute decisively for employability, business innovation and in reducing social asymmetries. This role of micro-companies in particular and, small and medium enterprises in general, is widely recognised in the literature. Nevertheless, the number of longitudinal studies that explicitly address the contribution of micro-companies to the European economy is reduced, and most of them are essentially reports produced by European and national agencies that analyse the importance of this phenomenon in their economies. This study intends to characterise the birth, death and survival rate of micro-companies in the European Union. The study adopts a quantitative and statistical approach in data analysis between 2008 and 2016, which allows us to characterise the evolution of these indicators and to understand which countries have the best and the worst performances.

2024

The size-luminosity relation of local active galactic nuclei from interferometric observations of the broad-line region

Autores
Amorim, A; Bourdarot, G; Brandner, W; Cao, Y; Clénet, Y; Davies, R; de Zeeuw, PT; Dexter, J; Drescher, A; Eckart, A; Eisenhauer, F; Fabricius, M; Feuchtgruber, H; Schreiber, NMF; Garcia, PJV; Genzel, R; Gillessen, S; Gratadour, D; Hönig, S; Kishimoto, M; Lacour, S; Lutz, D; Millour, F; Netzer, H; Ott, T; Paumard, T; Perraut, K; Perrin, G; Peterson, BM; Petrucci, PO; Pfuhl, O; Prieto, MA; Rabien, S; Rouan, D; Santos, DJD; Shangguan, J; Shimizu, T; Sternberg, A; Straubmeier, C; Sturm, E; Tacconi, LJ; Tristram, KRW; Widmann, F; Woillez, J;

Publicação
ASTRONOMY & ASTROPHYSICS

Abstract
By using the GRAVITY instrument with the near-infrared (NIR) Very Large Telescope Interferometer (VLTI), the structure of the broad (emission-)line region (BLR) in active galactic nuclei (AGNs) can be spatially resolved, allowing the central black hole (BH) mass to be determined. This work reports new NIR VLTI/GRAVITY interferometric spectra for four type 1 AGNs (Mrk 509, PDS 456, Mrk 1239, and IC 4329A) with resolved broad-line emission. Dynamical modelling of interferometric data constrains the BLR radius and central BH mass measurements for our targets and reveals outflow-dominated BLRs for Mrk 509 and PDS 456. We present an updated radius-luminosity (R-L) relation independent of that derived with reverberation mapping (RM) measurements using all the GRAVITY-observed AGNs. We find our R-L relation to be largely consistent with that derived from RM measurements except at high luminosity, where BLR radii seem to be smaller than predicted. This is consistent with RM-based claims that high Eddington ratio AGNs show consistently smaller BLR sizes. The BH masses of our targets are also consistent with the standard MBH-sigma* relation. Model-independent photocentre fitting shows spatial offsets between the hot dust continuum and the BLR photocentres (ranging from similar to 17 mu as to 140 mu as) that are generally perpendicular to the alignment of the red- and blueshifted BLR photocentres. These offsets are found to be related to the AGN luminosity and could be caused by asymmetric K-band emission of the hot dust, shifting the dust photocentre. We discuss various possible scenarios that can explain this phenomenon.

2024

Incidental Versus Ambient Visualizations: Comparing Cognitive and Mechanical Tasks

Autores
Moreira, J; Pinto, D; Mendes, D; Gonçlves, D;

Publicação
2024 INTERNATIONAL CONFERENCE ON GRAPHICS AND INTERACTION, ICGI

Abstract
Incidental visualizations allow individuals to access information on-the-go, at-a-glance, and without needing to consciously search for it. Unlike ambient visualizations, incidental visualizations are not fixed in a specific location and only appear briefly within a person's field of view while they are engaged in a primary task. Despite their potential, incidental visualizations have not yet been thoroughly studied in current literature. We conducted exploratory research to establish the distinctiveness of incidental visualizations and to advocate for their study as an independent research topic. We tested both incidental and ambient visualizations in two separate studies, each involving one specific scenarios: a cognitively demanding primary task (42 participants), and a mechanical primary task (28 participants). Our findings show that in the cognitively demanding task, both types of visualizations resulted in similar performance. However, in the mechanical task, ambient visualizations led to better results compared to incidental visualizations. Based on these results, we argue that incidental visualizations should be further explored in scenarios involving physical requirements, as these situations present the greatest challenges for their integration.

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