Methodology for WSN communication technologies automated field tests

Wireless Sensor Networks(WSN) are networks of devices used to sense and act that applies wireless radios to communicate. To achieve a successful implementation of a wireless device it is necessary to take in consideration the existence of a wide variety of radios available, a large number of communication parameters (payload, duty cycle, etc.) and environmental conditions that may affect the device’s behaviour. However, to evaluate a specific radio towards a unique application it might be necessary to conduct trial experiments, with such a vast amount of devices, communication parameters and environmental conditions to take into consideration the number of trial cases generated can be surprisingly high. Thus, making trial experiments to achieve manual validation of wireless communication technologies becomes unsuitable due to the existence of a high number of trial cases on the field. To overcome this technological issue an automated test methodology was introduced, presenting the possibility to acquire data regarding the device’s behaviour when testing several technologies and parameters that care for a specific analysis. Therefore, this method advances the validation and analysis process of the wireless radios and allows the validation to be done without the need of specific and in depth knowledge about wireless devices

Assessment of improvement techniques effect on fatigue behaviour of friction stir welded aerospace aluminium alloys

AbstractThis research work is based on analysis of the improvement of friction stir welded joints of the aerospace aluminium alloy AA2024-T351. Therefore, initially, the Taguchi method was used to obtain the optimal FSW parameters for improvement its mechanical behaviour. Then the fatigue resistance of base material, joints in as-welded condition and sound and defective FSW welded joints improved by grinding were detailed investigated. The influence of process parameters was addressed via statistical analysis of weld bead appearance parameters, mechanical tensile and bending resistance, metallurgical features and hardness field characterization. Validation tests demonstrate the Taguchi design’s feasibility in the optimization of the FSW parameters and fatigue results show the resistance of improved welded joints overcoming base material

Monitoring of the mechanical load and thermal history during friction stir channelling under constant position and constant force control modes

UID/EMS/50022/2019 UID/EMS/00667/2019In the present investigation, constant position and constant force process control modes; and representative process temperature measurements were analysed during the application of the friction stir channelling process. The experimental tests were carried out using rolled plates of AA5083-H111 with thickness of 15 mm. Results show that the FSC process was found not stable during the forward traverse movement stage when it is performed via position control. For both control modes, the tool was subjected to a more severe loading during the initial plunge than during the channelling period. Moreover, it was found that the tool vertical position is not significantly affected during the channelling stage when the process was force controlled. From the temperature measurements carried out, it was recorded a maximum process temperature of about 330 °C.publishersversionpublishe

Automatic pre-bended customized prosthesis for pectus excavatum minimal invasive surgery correction

Pectus excavatum is the most common deformity of the thorax. A minimally invasive surgical correction is commonly carried out to remodel the anterior chest wall, by employing an intrathoracic convex prosthesis in substernal position. The process of prosthesis modeling and bending still remains an area of improvement. The authors developed a new system, i3DExcavatum, which can automatically model and bend the bar preoperatively based on a thoracic CT-scan. This paper presents a comparison between automatic and manual bending. The i3DExcavatum was used to personalize prosthesis for 41 patients who underwent pectus excavatum surgical correction between 2007 and 2012. Regarding the anatomic variations, the soft tissue thicknesses external to the ribs show that symmetric or asymmetric patients have always asymmetric variations by comparing both patients’ sides. It highlighted that the prosthesis bar should be modeled according to each patient ribs position and dimension. The average differences between the skin and costal line curvature lengths were 84±4 mm and 96±11mm, for male and female patients, respectively. On the other hand, the i3DExcavatum ensured a smooth curvature of the surgical prosthesis and was capable to predict and simulate a virtual shape and size of the bar for asymmetric or symmetric patients. In conclusion, the i3DExcavatum allows preoperative personalization according to the thoracic morphology of each patient. It reduces surgery time and minimizes the margin error induced by the manual bended bar shape that only uses a template that copies the chest wall curvature

The influence of chemical reaction conditions upon poly(styrene‐methyl methacrylate‐acrylic acid) synthesis: Variations in nanoparticle size, colour and deposition methods

Monodisperse latex nanospheres of poly(styrene‐methyl methacrylate‐acrylic acid) with different sizes were synthetised by soap‐free emulsion copolymerisation and applied onto polyamide 6,6 fabrics by two methods, ie, gravitational sedimentation and dip‐drawing. Different‐sized nanospheres were synthetised by varying temperature and stirring velocity as reaction parameters. Scanning electron microscopy and scanning transmission electron microscopy were used to evaluate nanosphere sizes and deposition structures. The results showed two different nanosphere structural arrangements on the fabric surface, a hexagonal packed centre structure in the even surfaces and a square arrangement in the out‐of‐plane surfaces. Different colours were observed according to particle size, namely, violet (ca. 170 nm), blue (ca. 190 nm), green (ca. 210 nm), yellow (ca. 230 nm) and red (ca. 250 nm). An iridescence effect was also observed, displaying different colours at different observation angles. By controlling the size of the nanospheres it was possible to obtain different, brilliant and iridescent colours. Using different nanosphere sizes it was possible to obtain different interplanar distances and to control the light scattering in the crystalline lattice planes, obtaining Bragg diffraction patterns.Fundação para a Ciência e a Tecnologia, Grant/Award Number: IF/00071/2015, PTDC/CTM-TEX/28295/2017 , SFRH/BD/145269/2019 and UID/CTM/00264/2019; European Regional Development funds (FEDER); Competitiveness and Internationalization Operational Program (POCI)—COMPETE, Grant/Award Number: POCI-01-0145-FEDER-0071

Multiyear and multi-criteria AC Transmission Expansion Planning model considering reliability and investment costs

One of the major concerns in Power Systems issurely related with their reliability. Long-term expansionplanning studies traditionally use the well-known deterministic"N-1" contingency criterion. However, this criterion is appliedbased on worst-case analyses and the obtained plan mayoriginate over-investments. Differently, probabilistic reliabilityapproaches can incorporate different type of uncertainties thataffect power systems. In this work, a long term multi-criteriaAC Transmission Expansion Planning model was developedconsidering two objectives - the probabilistic reliability indexExpected Energy Not Supplied (EENS) and the investment cost.The Pareto-Front associated with these two objectives wasobtained using Genetic Algorithms and the final solution wasselected using a fuzzy decision making function. This approachwas applied to the IEEE 24 Bus Test System and the resultsensure its robustness and efficiency