Centre for Mechanical and Aerospace Science and Technologies

Funder

Organizational Unit

Publications

Decision support system to assign food price rebates on the basis of quality decline

Publication . Maciel, Vinicius Biasutti Pitol; Matos, Cláudia; Lima, Tânia M.; Gaspar, Pedro Dinis; Santos, Fernando Charrua

In order to reduce food waste, fruits and vegetables in special, in small and medium markets sizes, caused by loss of quality at the end of shelf life, an appropriate pricing method was created to maximize profit of seller. The method it was based on an acquisition of primary data, through questionnaires appropriate to the theme, and, subsequently, these primary data was used for mathematical modeling using a pricing dynamic method. As a last step this work, was development a spreadsheet application, where the seller can found a ideal point of order, size of stock and best price to sell. This way, using the application, the goal of reduction of food waste in fruit products is expected.

2019-11Journal article

Open access

Modelling of elastic modulus of CaZrO3-MgO composites using isotropic elastic and anisotropic models

Publication . Nunes-Pereira, João; Carneiro, Pedro; Maceiras, Alberto; Baudin, Carmen; Pereira Silva, A

Starting from synthetic raw materials (CaZrO3 and MgO), microstructural and mechanical properties were optimised in order to obtain dense multiphasic ceramic, then finite element method (FEM) of an equimolar (1:1) CaZrO3-MgO composite was performed in order to obtain the effective elastic modulus. Composite presents two main phases of orthorhombic CaZrO3 (81.5 wt.%) and cubic MgO (18.5 wt.%); For 1500 °C, relative density of 99.9%, characteristic strength of 168 MPa, hardness of 7.8 MPa and toughness of 2.5 MPa.m1/2 were obtained. FEM simulation was performed using two representative volume elements (RVE’s) with edge lengths of 14 μm (933 grains) and 17 μm (1670 grains), using isotropic elastic model, and anisotropic on specific set of crystallographic planes. The results of FEM using isotropic approach for the two RVE’s are perfectly aligned with the experimental (245 GPa), while the anisotropic model shows a difference of 6.5%.

2020Journal article

Restricted access

Society 5.0 as a Result of the Technological Evolution: Historical Approach

Publication . Pereira, Andreia G.; Lima, Tânia M.; Santos, Fernando

In the XX century, arises the mass production implemented by Henry Ford to overcome the period of crisis lived in the World. In 1988, the term Lean emerged and this philosophy successfully challenged the mass production implemented in the automotive industry, focused on customers’ requirements and satisfaction with the minimum use of resources and waste elimination. A Lean environment can be a promoter in the implementation of the fourth industrial revolution, named Industry 4.0 (I4.0). In the succession of Industry 4.0 emerged the Society 5.0 in Japan, as a strategy to deal with the impact of an ageing population. The focus of this quiet revolution is the humankind and the creation of conditions to promote a happy, motivated and satisfied society with more time for leisure and consequently increase productivity and wealth. This article presents a historical approach to the technological evolution of productive systems, and their influence on societies.

2020Book part

Restricted access

High deformation multifunctional composites: materials, processes, and applications

Publication . Costa, Pedro; Nunes-Pereira, João; Rial Tubio, Carmen; Dios, Jose Ramón; Lanceros-Mendez, Senentxu

Structural health monitoring (SHM) is a nondestructive process of collecting and analyzing data from structures to evaluate their conditions and predict the remaining lifetime. Multifunctional sensors are increasingly used in smart structures to self-sense and monitor the damages through the measurements of electrical resistivity of composite materials. Polymer-based sensors possess exceptional properties for SHM applications, such as low cost and simple processing, durability, flexibility, and excellent piezoresistive sensitivity. Thermoplastics, thermoplastic elastomers, and elastomer matrices can be combined with conductive nanofillers to develop piezoresistive sensors. Polymer, reinforcement fillers, processing and design have critical influences in the overall properties of the composite sensors. Together with the properties of the functional composites, environmental concerns are being increasingly relevant for applications, involving advances in materials selection and manufacturing technologies. In this scenario, additive manufacturing is playing an increasing role in modern technological solutions. Stretchable multifunctional composites applications include piezoresistive, dielectric elastomers (mainly for actuators), thermoelectric or magnetorheological materials. In the following sections, piezoresistive materials and applications will be mainly addressed based on their increasing implementation into applications.

2021Book part

Restricted access

Synthetic polymer-based membranes for lithium-ion batteries

Publication . Martins, Pedro; Nunes-Pereira, João; Lanceros-Mendez, Senentxu; Costa, C. M.

Efficient energy storage systems are increasingly needed due to advances in portable electronics and transport vehicles, with lithium-ion batteries standing out among the most suitable energy storage systems for a large variety of applications. In lithium-ion batteries, the porous separator membrane plays a relevant role as it is placed between the electrodes, serves as a charge transfer medium, and affects the cycle behavior. Typically, porous separator membranes are comprised of a synthetic polymeric matrix embedded in the electrolyte solution. The present chapter focus on recent advances in synthetic polymers for porous separation membranes as well as on the techniques for membrane preparation and physicochemical characterization. The main challenges to improve the synthetic polymer performance for battery separator membrane applications are also discussed.

2020Book part

Restricted access