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Publications

2020

Towards a More Robust Non-Rigid Robotic Joint

Authors
Pinto, VH; Goncalves, J; Costa, P;

Publication
APPLIED SYSTEM INNOVATION

Abstract
The following paper presents an improved, low cost, non-rigid joint that can be used in both robotic manipulators and leg-based traction robotic systems. This joint is an improvement over the previous one presented by the same authors because it is more robust. The design iterations are presented and the final system has been modeled including some nonlinear blocks. A control architecture is proposed that allows compliant control to be used under adverse conditions or in uncontrolled environments. The presented joint is a cost-effective solution that can be used when normal rigid joints are not suitable.

2020

Special issue with selected papers from 2018 Brazilian Symposium on Computer Engineering (SBESC 2018)

Authors
Gotz, M; Vasques, F;

Publication
DESIGN AUTOMATION FOR EMBEDDED SYSTEMS

Abstract

2020

Advanced sensor-based maintenance in real-world exemplary cases

Authors
Albano, M; Ferreira, LL; Di Orio, G; Malo, P; Webers, G; Jantunen, E; Gabilondo, I; Viguera, M; Papa, G;

Publication
AUTOMATIKA

Abstract
Collecting complex information on the status of machinery is the enabler for advanced maintenance activities, and one of the main players in this process is the sensor. This paper describes modern maintenance strategies that lead to Condition-Based Maintenance. This paper discusses the sensors that can be used to support maintenance, as of different categories, spanning from common off-the-shelf sensors, to specialized sensors monitoring very specific characteristics, and to virtual sensors. This paper also presents four different real-world examples of project pilots that make use of the described sensors and draws a comparison between them. In particular, each scenario has unique characteristics requiring different families of sensors, but on the other hand provides similar characteristics on other aspects.

2020

A Framework for Longitudinal Analysis of University Spin-Offs

Authors
Almeida, F; Cunha, E;

Publication
Advances in Electronic Government, Digital Divide, and Regional Development - Leveraging Digital Innovation for Governance, Public Administration, and Citizen Services

Abstract
The creation of university spin-offs plays a fundamental role in the technology transfer process between universities and the business field. Universities have developed for themselves internal processes within their technology transfer offices in order to collect this information. However, this data is only available locally and often outdated. Furthermore, the number of frameworks that allow the study and simultaneously access to this data in an integrated way is still small on a global scale, and in Portugal, there isn't a repository which contains this information. This study proposes the establishment of a framework for longitudinal analysis that could identify and characterize the evolution and performance of Portuguese university spin-offs. The repository is built exclusively in open source technologies and offers the potential to characterize and analyze the evolution and performance of university spin-offs in different perspectives, such as individual factors; organizational factors; institutional factors; and scientific, educational, and commercial outputs.

2020

Rail-to-Rail Timing Signals Generation Using InGaZnO TFTs For Flexible X-Ray Detector

Authors
Bahubalindruni, PG; Tiwari, B; Pereira, M; Santa, A; Martins, J; Rovisco, A; Tavares, V; Martins, R; Fortunato, E; Barquinha, P;

Publication
IEEE JOURNAL OF THE ELECTRON DEVICES SOCIETY

Abstract
This paper reports on-chip rail-to-rail timing signals generation thin-film circuits for the first time. These circuits, based on a-IGZO thin-film transistors (TFTs) with a simple staggered bottom gate structure, allow row and column selection of a sensor matrix embedded in a flexible radiation sensing system. They include on-chip clock generator (ring oscillator), column selector (shift register) and row-selector (a frequency divider and a shift register). They are realised with rail-to-rail logic gates with level-shifting ability that can perform inversion and NAND logic operations. These logic gates are capable of providing full output swing between supply rails, $V_{DD}$ and $V_{SS}$ , by introducing a single additional switch for each input in bootstrapping logic gates. These circuits were characterised under normal ambient atmosphere and show an improved performance compared to the conventional logic gates with diode connected load and pseudo CMOS counterparts. By using these high-performance logic gates, a complete rail-to-rail frequency divider is presented from measurements using D-Flip Flop. In order to realize a complete compact system, an on-chip ring oscillator (output clock frequency around 1 kHz) and a shift register are also presented from simulations, where these circuits show a power consumption of 1.5 mW and 0.82 mW at a supply voltage of 8 V, respectively. While the circuit concepts described here were designed for an X-ray sensing system, they can be readily expanded to other domains where flexible on-chip timing signal generation is required, such as, smart packaging, biomedical wearable devices and RFIDs.

2020

Modeling frequency response dynamics in power system scheduling

Authors
Zhang, ZY; Du, ES; Zhu, GP; Zhang, N; Kang, CQ; Qian, MH; Catalao, JPS;

Publication
ELECTRIC POWER SYSTEMS RESEARCH

Abstract
Since wind turbines or photovoltaic (PV) panels are generally connected to the power grid by power electronic inverters, the power system inertia is gradually decreasing along with the growing share of renewable energy. This jeopardizes the system frequency response dynamics so that the corresponding frequency security issue is becoming the bottle-neck factor that restricts the development of high renewable energy penetration. Consequently, power system scheduling models need to incorporate frequency dynamics. The difficulty lies in how to formulate the frequency security constraints from the perspective of hourly load-generation balance since the frequency dynamics have a shorter time scale (5 similar to 30 s). Several modeling methods have been proposed based on different assumptions and simplifications. However, their accuracy is not clear. We first propose a novel method to formulate linear frequency security constraints, which considers more details of frequency response dynamics. Then, an evaluation methodology is designed to quantify the accuracy of those frequency constraints. Using this evaluation method, we compare two typical methods in recent literature with the proposed method. The results show the effectiveness and superiority of our proposed method.

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