Navegando por Autor "Silva, Thiago Henrique"
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Item Alkali-activated materials produced using high-calcium, high-carbon biomass ash.(2022) Silva, Thiago Henrique; Lara, Luis Felipe dos Santos; Silva, Guilherme Jorge Brigolini; Provis, John Lloyd; Bezerra, Augusto Cesar da SilvaEucalyptus ash (EA) was used in this study as a high calcium ash (HCA) precursor for alkali-activated binders. The EA used also has high carbon unburned (High loss on ignition). This type of ash is one of the waste products from biomass-fuelled thermoelectric plants, and annually thousands of tons are discarded as a by-product of the energy generation process in Brasil, but it is rich in unburnt carbon which means that it is challenging to use in cementitious systems. Eucalyptus is a biomass that removes CO2 from the atmosphere by photosynthesis and part of this carbon content remains in the ashes, generating CO2 capture when EA is incorporated in the production of alkali-activated binders. The objective of the present study was to evaluate the properties of the material obtained by the alkali-activation of the high-calcium high-carbon biomass ash to generate a cementitious binder, with different pastes proportions of EA and silica fume (SF), activated by sodium hydroxide. With the different pastes, mortars were produced using standardized sand. The results obtained from the pastes and mortars were satisfactory in several aspects. The mechanical results of the alkali-activated mortars were comparable those of Portland cement mortars. Mortars degraded methylene blue more efficiently in illuminated conditions, even after high adsorption for 24 h in the dark. The content of leached ions in the remaining solutions met potability standards.Item Towards scalable mobile crowdsensing through device-to-device communication.(2018) Mota, Vinícius Fernandes Soares; Silva, Thiago Henrique; Macedo, Daniel FernandesIn mobile crowdsensing, users have a central role providing sensed data using their portable devices. Mobile crowdsensing applications have become quite popular nowadays. However, these applications can be bandwidth eager, big battery drainers, and may demand intensive network usage, which could exceed the allowance of users' mobile data plan. All these aspects may prevent users to contribute sensed data and also get valuable information from the service, which can impact the sustainability of the system. The Device-to-Device (D2D) communication paradigm arises as an approach to relieve data traffic generated by these applications, helping to let the system more sustainable. For instance, devices with a more reliable network connection can offload the network by disseminating data to other devices through D2D communication. However, mobile crowdsensing and D2D communication assume that users cooperate and allow their portable devices to be used for sensing and communication. In this work, we address the cooperation problem in the context of D2D communication to enhance mobile crowdsensing platforms. We first discuss how D2D communication can enhance mobile crowdsensing. Next, we propose and evaluate a general framework joining mobile crowdsensing and D2D communication. This framework abstracts applications defined by the sensing platforms, it decides the communication mode – whether infrastructure or D2D – and which incentive mechanisms must be used to engage participants to cooperate. We show evidence that this new approach could lead to a more sustainable mobile crowdsensing usage.