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Determination of the biochemical methane potential of swine hydrolyzate
Publication . Domingues, Paulo Simão; Sousa, Helena Pala; Oliveira, Nelson Simões; Ribeiro, Ana M.; Ferreira, Alexandre
Swine farming generates remains of births and animals that die during the process. Implementing a plan to eliminate these materials by hydrolysis process results in an animal by-product called swine hydrolyzate. The treatment of this by-product through its application in the anaerobic digestion process can also represent its conversion into a resource for energy production. Thus, the present study focuses on this by-product as a potential substrate for anaerobic digestion, evaluating the methane production potential. The results show biogas production with an average methane content of about 70 %. Theoretical biochemical methane potential was 967.95 ± 0.11 mL g VS−1, which represented a bioconversion efficiency of 59.97 ± 3.54 % and 62.26 ± 0.43 %, considering the experimental results of 580.47 ± 34.29 mL g VS−1 and 602.67 ± 4.16 mL g VS−1, respectively. By comparing the experimental biochemical methane potential with the predicted value using the modified Gompertz model, it was possible to conclude that the maximum methane production rate was 73.46 ± 0.36 mL g VS−1 day−1, with a digestion time of 18 days to obtain 90 % of the methane production potential.
Production and Material Types for Pallets: A Review
Publication . Pulgar, Alejandro; Oliveira, Nelson S.
Pallets are used extensively in the supply chain for the transportation of goods between suppliers, manufacturers, distributors, and retailers. This article reviews pallet production, its mechanical properties related to material options (according to European standards and industrial applications) and management systems. In the global supply chain, polymer, metal, and composites pallets compete in line with the concept of sustainable development. The supply chain requires pallets according to specific characteristics, such as sizing, maximum load capacity, durability (lifespan), cost and more information is needed about their environmental impacts. Some types of pallets (stringer and blocks) can have several configurations, number, width and spacing. Furthermore, the pallets management system is divided in three models; EMP (extensive management of pallets), TPO (transfer pallet’s ownership) and PR (pallet rent), where suppliers, distributors and retailers select the most suitable option. The systematic review of the literature identified 15 documents with the key methodological elements, such as, specifications, inventory data, goals, and system boundaries for a life cycle assessment of pallets.
CrowdTargeting: Making Crowds More Personal
Publication . Costa, Joana; Silva, Catarina; Ribeiro, Bernardete; Antunes, Mário
Crowdsourcing is a bubbling research topic that has the potential to be applied in numerous online and social scenarios. It consists on obtaining services or information by soliciting contributions from a large group of people. However, the question of defining the appropriate scope of a crowd to tackle each scenario is still open. In this work we compare two approaches to define the scope of a crowd in a classification problem, casted as a recommendation system. We propose a similarity measure to determine the closeness of a specific user to each crowd contributor and hence to define the appropriate crowd scope. We compare different levels of customization using crowd-based information, allowing non-experts classification by crowds to be tuned to substitute the user profile definition. Results on a real recommendation data set show the potential of making crowds more personal, i.e. of tuning the crowd to the crowdtarget.
Conexões Virtuais e Solidão: Explorando o Envelhecimento Ativo através do Facebook entre os Idosos
Publication . Ribeiro, Jaime; Reis, Margarida; Vidal Barrantes, Francisco Javier; Custódio, Susana
Introdução: As trajetórias de desenvolvimento dos idosos são influenciadas pela sua capacidade de lidar bem com as mudanças que ocorrem nas diversas áreas da vida, assim como com eventos como a reforma, a institucionalização e a perda de amigos e cônjuges. Estas transições muitas vezes levam à solidão e ao isolamento social entre os mais velhos. Num contexto de uma sociedade cada vez mais envelhecida e tecnológica, o Facebook destaca-se como a rede social mais utilizada, inclusive em Portugal, sendo cada vez mais adotado pelos idosos. Métodos: Este estudo adotou uma abordagem mista e descritivo-correlacional. Para recolher os dados, foi utilizado um questionário online, que incluiu a Escala de Solidão da UCLA, bem como entrevistas. A amostra consistiu em 269 indivíduos com 55 anos ou mais, aposentados e utilizadores do Facebook. Resultados: Os resultados indicaram que a maioria dos idosos utiliza o Facebook para socializar, comunicar, obter conhecimento e manter contato com familiares distantes, servindo como um meio de evitar a solidão. Conclusões: O Facebook parece desempenhar um papel significativo na redução do isolamento social entre os idosos, facilitando a manutenção de redes sociais e familiares, o que é crucial para um envelhecimento ativo.
Constrained encoding structures for computational complexity scalability in HEVC
Publication . Correa, Guilherme; Assunção, Pedro; Cruz, Luis A. da Silva; Agostini, Luciano
The High Efficiency Video Coding standard shows improved compression efficiency in comparison to previous standards at the cost of higher computational complexity. In this paper, a complexity scalability method for HEVC encoders based on the dynamic adjustment of the number of constrained coding treeblocks is proposed. The method limits the Prediction Unit shapes and the maximum tree depth used in each Coding Treeblock in order to decrease the number of evaluations performed in the Rate-Distortion Optimization process. The encoder is capable of trading off computational complexity and compression efficiency while still maintaining the encoding time per Group of Pictures (GOP) under a pre-defined target. The encoding complexity can be decreased in up to 60% when compared to the original encoder at the cost of small Bjontegaard Delta (BD)-rate increases.