Furtado, Pedro, Maria Isabel Gomes, and Ana Paula Barbosa-povoa. "
Design of an electric and electronic equipment recovery network in Portugal – Costs vs. Sustainability."
Computer Aided Chemical Engineering. Eds. E. N. Pistikopoulos, M. C. Georgiadis, and A. C. Kokossis. Vol. 29. 2011. 1200-1204.
AbstractIn the last few decades there has been a massive growth in the Waste of Electric and ElectronicEquipment (WEEE). Part of these residues was already properly treated in some countries, but the lack of environmentally friendly options forced the European Union (EU) to take action. Two EU directives were created based on reduction, reutilization and recycling of WEEE. The need to properly designrecoverynetworks for such products appears as mandatory, where not only the economic aspects should be accounted for but also the environmental ones. The present paper addresses this problem and presents a generic optimization model for the design and planning of a recovery and treatment network of WEEE, minimizing both the costs and the environmental impacts that arise from the activity performed.
The model is applied to the real case of Amb3E, the Portuguese Association for the Management of Waste of Electric and ElectronicEquipment. Since its formation, in 2006, this organization has been registering an immense growth in the volume of residue collected, and faces now the necessity of reformulating its recoverynetwork. Both the actual cost structure and the best possible cost structure for Amb3E, given by the optimization of the model, are analyzed. These two scenarios are compared in order to turn clear the differences between them and to assess how the recoverynetwork of Amb3E can be improved through optimization. A similar analysis is performed from an environmental impacts perspective.
Carvalho, Carlos, Guilherme Lavareda, and Nuno Paulino. "
A DC-DC Step-Up mu-Power Converter for Energy Harvesting Applications, Using Maximum Power Point Tracking, Based on Fractional Open Circuit Voltage."
TECHNOLOGICAL INNOVATION FOR SUSTAINABILITY. Ed. LM CamarinhaMatos. Vol. 349. IFIP Advances in Information and Communication Technology, 349. Soc Collaborat Networks; IFIP WG 5.5 COVE CoOperation Infrastructure Virtual Enterprises & Elect Business; IEEE Ind Elect Soc; U2; Uninova, 2011. 510-517.
AbstractA DC-DC step-up micro power converter for solar energy harvesting applications is presented. The circuit is based on a switched-capacitor voltage tripler architecture with MOSFET capacitors, which results in an, area approximately eight times smaller than using MiM capacitors for the 0.131 mu m CMOS technology. In order to compensate for the loss of efficiency, due to the larger parasitic capacitances, a charge reutilization scheme is employed. The circuit is self-clocked, using a phase controller designed specifically to work with an amorphous silicon solar cell, in order to obtain the maximum available power from the cell. This will be done by tracking its maximum power point (MPPT) using the fractional open circuit voltage method. Electrical simulations of the circuit, together with an equivalent electrical model of an amorphous silicon solar cell, show that the circuit can deliver a power of 1132 mu W to the load, corresponding to a maximum efficiency of 66.81%.
Louren{\c c}o, João, Diogo Sousa, Bruno C. Teixeira, and Ricardo Dias. "
Detecting concurrency anomalies in transactional memory programs."
Comput. Sci. Inf. Syst.. 8 (2011).
AbstractSoftware transactional memory is a promising programming model that adapts many concepts borrowed from the databases world to control concurrent accesses to main memory (RAM). This paper discusses how to support revertible operations, such as memory allocation and release, within software libraries that will be used in software memory transactional contexts. The proposal is based in the extension of the transaction life cycle state diagram with new states associated to the execution of user-defined handlers. The proposed approach is evaluated in terms of functionality and performance by way of a use case study and performance tests. Results demonstrate that the proposal and its current implementation are flexible, generic and efficient
R., Neagu E., C. Dias, Lança M. Carmo, Igreja R., Inacio P., and Marat-Mendes J. N. "
Discrimination between Space Charge and Dipolar Contributions in Ferroelectric Polymers."
14th International Symposium on Electrets. International Symposium on Electrets. 2011.
AbstractThe final thermally stimulated discharge current method allows a better selection of the experimental conditions for sample polarization. By decreasing the ratio between the charging time and the discharging time, the apparent peak is of the same order of magnitude as the genuine peaks and there is only a partial overlap between then. Two peaks have been identified for polyamide 11, one associated with the glass transition around 60 °C and the second associated with the Curie transition around 96 °C.