Logo do repositório

Percorrer por autor "Santos, L."

A mostrar 1 - 2 de 2
  • Binder system for fused deposition of metals
    Publication . Cruz, N.; Santos, L.; Vasco, Joel; Barreiros, F. M.
    Fused Deposition of Metals (FDMe) is a technique developed to produce metallic components, based on the extrusion of metal/binder filaments to form layer by layer three dimensional objects. Filament materials must contain a high content of metallic powder to prevent shrinkage on thermal treatments like debinding and sintering, without compromising adequate rheological properties during the extrusion process. This research aims developing an FDMe system using metal/binder feedstocks in pellet/granule instead of filaments. The present work is focused on establishing a suitable binder system for fused deposition of carbonyl iron feedstocks. Binder systems based on Polyethylene Wax (PEW) or Paraffin Wax (PW), Polyethylene Glycol (PEG) and Polypropylene (PP) were investigated concerning their thermal and rheological properties. The rheological data showed that the binder systems containing PW presents lower viscosity than those having PEW. Thus, a binder system based on the former component was selected to assure appropriate rheological properties of carbonyl iron feedstocks with high content of solids for FDMe.
    2013Comunicação em conferência Acesso aberto Ver mais
  • Study of the requirements of an autonomous system for surface water quality monitoring
    Publication . Barros, M.; Granchinho, P.; Ferreira, C.; Neves, P.; Magalhães, H.; Santos, L.; Lopes, B.; Marques, J.; Pinho, H.; Mourato, Sandra
    In recent years, there has been increasing awareness of the preservation, protection and sustainable use of natural resources. Water resources, being one of the most important natural resources, face major threats due to contamination by pollutants of various types and origins. Maintaining the quality of water resources requires more robust, reliable and more frequent monitoring than traditional techniques of data collection based on sporadic, discontinuous and manual processes. The management of large geographical areas, the insufficient spatiotemporal discretization of the values of samples collected by traditional processes and the unpredictability of natural phenomena, require a new approach to data collection procedures. This article, which is the result of ongoing research, defines the technical requirements and technologies used in a continuous and regular monitoring of surface water quality in freshwater systems, whose data acquisition system helps to identify the sources of pollution and the contaminants flow along the waterways. The design of a versatile real-time water quality monitoring system, which, due to its environmental constraints should be based on renewable energies and wireless transfer of energy, will contribute to improve the management and effective protection of water resources.
    2024-01-12Artigo científico Acesso aberto Ver mais