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Wendler E.,University of Vienna | Sobolev N.A.,niversidade Of Aveiro3810 193 Aveiroportugal | Lorenz K.,Instituto Superior Tecnicouniversidade Of Lisbon
Physica Status Solidi (B) Basic Research | Year: 2016

In this article, ion-beam induced effects in multi-layered III-V semiconductor structures are reviewed. Besides doping, important effects occurring during ion irradiation are defect formation and diffusion, amorphisation and intermixing. It is shown that these processes are closely related to each other. In layered systems consisting of group III-phosphides and -arsenides, which can be amorphised by ion implantation, cascade mixing is the dominant mixing mechanism at low temperatures. At a critical temperature, the crystalline structure is retained after implantation and the mixing efficiency may drop down because cascade mixing is more efficient in amorphous semiconductors than in their crystalline counterparts. A further increase of temperature results in an increase of the mixing efficiency due to thermally enhanced processes. Although much less experimental data exist on ion-beam induced effects in layered group III-nitride systems, the results suggest that these systems are not amorphised during ion implantation. In this case, the experimental results can be explained assuming recoil rather than cascade mixing to occur with the former being much weaker than the latter. A few applications of ion implantation of multi-layered semiconductor systems are addressed. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source


Ji C.,Jiangsu University of Science and Technology | Xu S.,Instituto Superior Tecnicouniversidade Of Lisbon
Ocean Engineering | Year: 2014

The hybrid model test method has been regarded as the most reliable method to investigate the dynamics of deepwater floating systems when the wave basin is not large enough to conduct the full water depth model tests at reasonable model scales. In order to get the reliable experimental results, the truncation factor should be less than 5. However, as the offshore oil and gas industry moves towards deeper waters, the model tests of floating structures carried out at the wave basin with reasonable model scales need to be revamped. The objective of the present study is to investigate the feasibility of largely truncated hybrid model test for the deep water floating systems. The hybrid model test techniques and the dynamic behaviors of the truncated mooring lines are also studied. In order to achieve the static and dynamic similarities easily in the largely-truncated model tests, an optimization design method of the truncated mooring system is proposed, and the similarities of platform motion responses as well as the mooring lines dynamics are investigated in the largely-truncated model tests. To verify the present method, a deepwater semisubmersible system operated in 1500 m and 1000 m water depth is truncated to 200 m water depth based on the static equivalent principle (the truncation factors are 7.5 and 5 respectively), and the dynamically similar design is implemented to the model tests which are carried out at China Ship Scientific Research Center wave basin. The motion responses of the platform and the mooring line dynamics are obtained. These experimental results are used to compare with the numerical simulation, which is based on the full time domain coupled dynamic analysis method. The comparisons show that the numerical results are in good agreement with the model measurements. © 2014 Elsevier Ltd. All rights reserved. Source


Pedrosa P.,University of Minho | Fiedler P.,TU Ilmenau | Alves E.,Instituto Superior Tecnicouniversidade Of Lisbon | Barradas N.P.,Instituto Superior Tecnicouniversidade Of Lisbon | And 3 more authors.
Plasma Processes and Polymers | Year: 2015

Several plasma treatments using argon, oxygen, and nitrogen are studied in order to increase the interfacial adhesion of the polyurethane/Ag:TiN system to be used as biopotential electrodes. The optimized plasma treatments conditions (100W, 15min, regardless of the gas) promote a steep decrease of the water contact angle values. The observed chemical and topographic alterations translate into excellent polyurethane/Ag:TiN interfacial adhesion of the plasma treated samples. The in-service validation of the proposed Ag:TiN-coated PU multipin electrodes is performed by acquiring EEG signals in parallel with the standard wet Ag/AgCl electrodes. No considerable differences are found in terms of shape, amplitude, and spectral characteristics of the signals when comparing reference wet and dry electrodes. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source


Brotas G.,University of Lisbon | Farinhas J.,University of Lisbon | Ferreira Q.,University of Lisbon | Rodrigues R.,University of Lisbon | And 5 more authors.
Journal of Polymer Science, Part A: Polymer Chemistry | Year: 2014

Several crosslinkable oxetane-functionalized copolymers, containing regio-regular segments of 3-hexylthiophene, are synthesized using the Grignard metathesis polymerization. The optical and electrochemical properties of the new polymers, both in the soluble and crosslinked forms, are reported. These polymers are used in the preparation of organic photovoltaics upon blending with PCBM as electron-acceptor. The effect of the crosslinking of these copolymers, once the blend films are formed, on the devices performance is also studied. In particular, the insertion of the oxetane-functionalized thiophene comonomers leads to a decrease of the devices performance, which is further decreased upon crosslinking of the copolymer. However, the stability of the devices overall improves upon crosslinking of the copolymer. Copyright © 2013 Wiley Periodicals, Inc. Source

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