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Publicações

2022

Design and experimental tests of an Imbert type downdraft gasifier prototype and clean-up system for small-scale biomass-based power generation

Autores
Mendonça; Mantilla; Patela; Silva; Resende;

Publicação
Renewable Energy and Environmental Sustainability

Abstract
This paper addresses the design, development and experimental tests of a prototype of fuel gas generation system based on biomass gasification for small-scale applications, around 5?kW. It comprises the small scale downdraft gasifier and the gas cleaning system aiming to clean-up the producer gas to be used in the upstream Internal Combustion Engine (ICE). The design of the downdraft gasifier prototype follows the methodologies that have been reported on the available literature. However, since these methodologies apply to gasifiers with larger rated powers, the adopted methodology is based on the extrapolation of the main parameters used for larger gasifiers design. For runing the ICE the producer gas requires to have a specific gas composition with an acceptable range of impurities. Therefore, a clean-up system was proposed following three stages: in first instance a hot gas clean-up using a cyclone designed to eliminate particles and compounds; then a heat exchanger was used for cooling the gas to condensate tars and water; finally a cold gas clean-up is performed by filtration using two filter steps: the first one using organic material (biomass) and the second one using a polypropylene cartridge filter. Experimental tests were performed using the developed imbert downdraft gasifier prototype, using pellets as feedstock. The preliminary results allow verifying several drawbacks that will difficult an effective integration of the developed prototype for small scale power generation applications based on ICE using low density feedstock.

2022

WindsPT e-Science platform for wind measurement campaigns

Autores
Gomes D.F.; Lopes J.C.; Palma J.M.L.M.; Senra F.; Dias S.; Coimbra I.L.;

Publicação
Journal of Physics: Conference Series

Abstract
Experimental field campaigns for collecting wind data, essential for academic research and the wind energy industry, are non-trivial due to the complex equipment and infrastructure required. This paper reports the latest developments of the WindsPT e-Science platform for planning, executing, and disseminating wind measurement campaign data. Existing e-Science platforms have been developed for more generic domains, preventing them from capturing the details and requirements of the field. Additionally, we propose a protocol for transferring large volumes of data from the in-site devices to our platform, ensuring data replication. With an easy-to-use Web interface, WindsPT promotes collaboration between participants, disseminates results among the stakeholders, publishes metadata, uses DOI, and includes metadata that enables machine-to-machine communication. The platform has multiple sections, with maps, images, and documents, where there is information about the location of the stations, positioning of the sensors, operating dates, photos, technical sheets, calibration documents, among others. The WindsPT platform has been used to host the Perdigão 2017 experimental campaign and proved to be a valuable tool during all the phases of this large field experiment. A new version of WindsPT, designed to be FAIR, host multiple campaigns, and include multiple cross-campaign shared features, as full-text search capabilities, is now developed and tested.

2022

Envelope estimation using geometric properties of a discrete real signal

Autores
Tarjano Santos, CH; Pereira, V;

Publicação
Digit. Signal Process.

Abstract

2022

Visual identity of cities: designers’ tools and meanings

Autores
Sarmento T.; Quelhas-Brito P.;

Publicação
Journal of Place Management and Development

Abstract
Purpose: This paper aims to identify and compare the graphical shapes and meanings attributed to place/city by the designer/creative/author of a city visual identity (VI) and by the client and designer’s peers. Design/methodology/approach: To identify and compare the graphical shapes and meanings attributed to place/city by the designer/creative/author of a city VI and by the client and designer’s peers. Findings: This paper analysed the way the visual culture of different stakeholders influenced the process and the construction of the iconographic meanings. Secondly, this paper assessed how the design tools impacted the creative process in that specific context. Practical implications: A demanding involvement of more participants in the design process can be worthy for a VI outcome. Visual identity of a city is both designer’s creative as a political process. The several aesthetical options decisions implied adaptation, trade-offs and negotiations. Originality/value: This research explains how the design tools and forms were used in the creative process of designers when conceiving the VI of a place. This research also reveals how a design work can have an effective impact on the sensory qualities emanating from city brands which are recognized by tourists and citizens. The consideration of the designer’s tools makes a relevant contribution to understand some underlying procedural issues.

2022

Dialogo: A Controlled Portuguese for Developing Agroecological Information Systems

Autores
Jaffe, MSD; Lopes, DMM; Reis, AM;

Publicação
INFORMATION SYSTEMS AND TECHNOLOGIES, WORLDCIST 2022, VOL 2

Abstract
Information systems can be useful tools to understand complex agroecological systems. Farmers and extensionists in the Global South may not have access to such information systems due limited resources, skills and opportunities. End-user development (EUD) has the potential to best suit local needs and conditions. This article summarises and furthers a research and development effort targeting communities as well as agroecological extension professionals and organisations in the Serra da Capivara Territory, Piaui, Brazil. In a retrospective ethnographic study we observed information abundance, topdown IS bias, informational competence and digital infrastructure limitations. A set of requirements was identified, with Portuguese syntax and semantics being crucial for an EUD solution. Based on these requirements a multiparadigm controlled natural language is specified and described as well as a prototype implementation and evaluation method. This language should provide a language that enables the end-user to develop IS suitable to their needs and conditions.

2022

An Oblivious Observed-Reset Embeddable Replicated Counter

Autores
Weidner, M; Almeida, PS;

Publicação
PAPOC'22: PROCEEDINGS OF THE 9TH PRINCIPLES AND PRACTICE OF CONSISTENCY FOR DISTRIBUTED DATA

Abstract
Embedding CRDT counters has shown to be a challenging topic, since their introduction in Riak Maps. The desire for obliviousness, where all information about a counter is fully removed upon key removal, faces problems due to the possibility of concurrency between increments and key removals. Previous state-based proposals exhibit undesirable reset-wins semantics, which lead to losing increments, unsatisfactorily solved through manual generation management in the API. Previous operation-based approaches depend on causal stability, being prone to unbounded counter growth under network partitions. We introduce a novel embeddable operation-based CRDT counter which achieves both desirable observed-reset semantics and obliviousness upon resets. Moreover, it achieves this while merely requiring FIFO delivery, allowing a tradeoff between causal consistency and faster information propagation, being more robust under network partitions.

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