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- Study on the fatigue strength of AA 6082-T6 adhesive lap jointsPublication . Pereira, António; Ferreira, J.M.; Antunes, F.V.; Bartolo, PauloA research study on the fatigue behaviour of aluminium alloy adhesive lap joints was carried out to understand the effect of surface pre-treatment and adherends thickness on the fatigue strength of adhesive joints. The adherend material used for the experimental tests was an aluminium alloy 6082-T6 in the form of thin sheets, and the adhesive used was a high strength epoxy (Araldite 420 A/B). The surface preparation included an abrasive preparation (AP joints) and sodium dichromate-sulphuric acid etch (CSA joints). A maximum fatigue strength was obtained for the CSA surface treatment with a 1.0 mm adherends' thickness. The fastest fatigue damage was related with a high surface roughness and a high stress perpendicular to adhesive surface, which helps to promote the adhesive failure. A numerical analysis was also performed to understand the effect of the adherends thickness on the stress level. Results showed an increase of the out-of-plane peak stresses with the increase of adherends thickness.
- A Java Software Stack for Resource Poor Sensor Nodes: Towards Peer-to-Peer JiniPublication . Costa, Nuno; Pereira, António; Serôdio, CarlosSensor networks have been referred to as part of the background infrastructure required to achieve ubiquitous computing. This has recently promoted a considerable amount of attention from the research community that concluded that existing protocols and techniques for service discovery, such as JINI or UPnP are not suitable for the case of resource poor, battery-powered sensor nodes. We do not really agree with this approach. We think that those protocols could be a good starting point to "power-up" sensor nodes with poor resources for ubiquitous computing support. Starting from this principle and recognizing that existing sensor node system software is not suitable for our purpose, we decided to build a new sensor node software stack. The result was a stand-alone Java Virtual Machine, suitable for sensor nodes with poor resources, an implementation of the ubiquitous TCP/IP communication stack and Jini based middleware to achieve automatic service discover and usage. This software stack was tailored to perfectly fit in the state-of-the-art Mica2 class of sensor nodes.
- IntelligentCart: Architecture of an Innovative System for the Acquisition of Products in Grocery StoresPublication . Santos, Diana S.S.; Pereira, António; Gonçalves, RamiroLarge grocery stores are nowadays used by millions of people for the acquisition of an enlarging number of products. Product acquisition represents a complex process that comprises time spent in corridors, product location and checkout queues. On the other hand, it is becoming increasingly difficult for retailers to keep their clients loyal and to predict their needs due to the influence of competition and the lack of tools that discriminate consumption patterns. In this article it is presented the proposal of an architecture and solution of an innovative system for the acquisition of products in grocery stores (IntelligentCart). The IntelligentCart explores emerging mobile technologies and automatic identification technologies (such as RFID) as a way to improve the quality of services provided by retailers and to augment the consumer value thus allowing to save time and money.