Automatic Circular Take-off and Landing of Tethered Motorized Aircraft

We consider a motorized aircraft tethered to a central anchorage point in a configuration similar to a control line model airplane. For this system, we address the problem of automatic take-off and landing (ATOL) with a circular path, whose center and radius are defined by the anchorage point and the tether length, respectively. We propose a hierarchical control architecture for ATOL and discuss the controllers designed for each control layer and for each of the flight phases. Simulation results are reported, showing the viability of the approach, but also showing the limitations on the maximum altitude attainable with a fixed-tether length. The tethered aircraft and the proposed ATOL control architecture are to be used in an Airborne Wind Energy System.Comment: Submitted to an international conferenc

Technical Note: Accuracy and repeatability of a new portable ultrasound pachymeter

Purpose: To assess the accuracy and repeatability of central corneal thickness (CCT) measurements taken with a new portable ultrasound (US) pachymeter.Methods: Central thickness measurements were taken with a portable pachymeter (SP-100 Handy; Tomey, Nagoya, Japan) and a conventional US pachymeter (Nidek UP-1000; Nidek Technologies, Gamagori, Japan) from 57 right corneas of 57 young adults (19 males, 38 females) aged 18-44 years (mean +/- S.D., 22.95 +/- 3.92). Three repeated measures were obtained and then compared to obtain the repeatability of each instrument and the agreement between the pachymeters. The three readings taken with the portable pachymeter were compared against each other in order to evaluate intra-session repeatability and bias of each individual measurement with respect to the mean of three.Results: Mean values of CCT were 537 +/- 35 mu m for conventional and 534 +/- 35 mu m for the new portable pachymeter. A high agreement was found between the two instruments (mean difference = 2.58 mu m; 95% CI 1.41-3.75 mu m) with only two eyes presenting differences larger than +/- 8.6 mu m which represents 95% CI in the Bland-Altman plots which represents 1.6% of the mean CCT. The first reading taken showed the highest agreement with the mean value for the portable pachymeter.Conclusions: The instrument tested in this study is able to take reliable measurements of corneal thickness even if a single reading is considered. Intra-session repeatability was very high, as was also the agreement between the average of three readings taken with the two US pachymeters.- (undefined

Experimental study of a double-diffusive system: application to solar ponds

A salt gradient solar pond is an artificial device used to collect and store solar thermal energy. A non-convective zone, in the middle of the solar pond, reduces thermal losses and allows a significant rise of temperature in the saltier lower zone where the solar thermal energy is stored. The non-convective zone, also named gradient zone, is characterized by a salinity gradient that increase the density with depth promoting the stability of this layer. The absorption of solar radiation in the pond creates a destabilizing temperature gradient in the non-convective zone that contradicts the density gradient. The different molecular diffusivities of heat and salt and the opposing effects on the vertical density distribution of the two gradients can lead to double-diffusive convection phenomena. In this context, a double-diffusive system has been studied experimentally in laboratory by heating a stratified salt layer from below. The instabilities caused by the destabilizing temperature gradients lead to the formation of convective zones separated from purely diffusive zone by thin interfaces. The main goals of this work are the study of the evolution of the double-diffusive layer and the analysis of the behaviour of the diffusive interface near conditions for which instabilities appear

Assessment of layer thickness and uniformity in railway embankments with Ground Penetrating Radar

In the aim of a national research project entitled “Interaction soil-rail track for high speed trains”, a protocol was established between the National Railway Network and four national research institutions to develop the knowledge concerning the methodology for the construction and quality control of the railway embankments and railtrack layers for high speed trains. One of the objectives of this protocol is to establish a methodology for quality control of construction layers by different available test methods. Nondestructive testing (NDT) methods are currently very attractive due to their ability to provide information about layer thickness and state condition without causing damage or requiring the removal of material samples. Within the NDT available, ground penetrating radar (GPR) is a very fast and reliable technique, whose advantage is the repeatability and the capability of acquiring continuous data. To reach the proposed goal, a trial embankment was constructed with different materials, layer’s thicknesses, water contents and compaction energy levels. GPR was used in two embankments, in order to detect the thickness of the sub-ballast layer located over the compacted sand layer and its uniformity along the track, but also along the cross-section of the track. In order to control some parameters of the sub-ballast layer, like thickness and uniformity, several metallic plates had been used in the base of the sub-ballast layer, along an alignment. It shows clearly the ability of GPR to detect the sub-ballast layer and its thickness variations along the profile

Antigenotoxic effects of quercetin, rutin and ursolic acid on HepG2 cells : evaluation by the comet assay

In the present study, the chemoprotective effects of quercetin, rutin and ursolic acid on tert-butyl hydroperoxide (t-BHP)-induced DNA damage in a human hepatoma cell line (HepG2) were investigated by the comet assay. To determine whether protection was due to direct chemical interactions alone or to cellular-mediated responses three different types of treatments were used: simultaneous incubation of cells with individual test compounds and the toxicant; pre-treatment with test compound before addition of the toxicant followed or not by a recovery period. The expression of Hsp70 was quantified by Western blotting to test the involvement of heat shock proteins in the cellular responses to the test compounds. In addition, effects on proliferation were evaluated by the MTT assay. The results show that quercetin and ursolic acid prevented DNA damage and had antiproliferative properties in HepG2 cells suggesting an anticarcinogenic potential for these compounds. The protective effects of quercetin against t-BHP-induced DNA damage seem to be due to both direct effects on t-BHP toxicity and to cellularly mediated indirect effects which reflect the potentiation of the cellular antioxidant defenses. Ursolic acid seems to exert effects only through cellularly mediated mechanisms since it was not protective in simultaneous incubation. Quercetin and ursolic acid also showed to increase the rate of DNA repair. Rutin did not have effects at any level. These results, obtained with liver cells, emphasize and confirm the chemopreventive potential of quercetin and ursolic acid, which may help explain the lower cancer incidence in human population with high dietary intakes of fruits and vegetables. These results also demonstrate that Hsp70 is not involved in the observed effects in HepG2.Fundação para a Ciência e a Tecnologia (FCT) - UMINHO/POCI-62040/BI/1/06, SFRH/BPD/26316/2006, POCI/AGR/62040/2004

Cork extractives exhibit thermo-oxidative protection properties in polypropylene-cork composites and as direct additives for polypropylene

The thermo-oxidative stability of polypropylene (PP) in composites containing 15 wt.% of cork and the performance of selected cork extracts as stabilizing additives for PP was evaluated by Oxidation Induction Time (OIT) and by Oxidation Onset Temperature (OOT). The results showed that cork increases the OIT of PP in the composite and it was identified that the cork extractives fraction is responsible for such behavior. Selected cork extracts with high antioxidant capacity (determined by dpph radical scavenging and oxygen reactive absorbance capacity assays) were compounded by extrusion with PP in 0.5 and 1.5 wt.%. It was found that the ethanol extract is the most effective as thermo-oxidative stabilizer for PP. At the loading level of 1.5%, the OIT increases from 3.8 (neat PP) to 29.7 min at 200 Â°C and from 1.2 (neat PP) to 9.0 min at 220 Â°C. The OOT also increases from 216 Â°C (neat PP) to 247 Â°C. Mechanical tests, performed on PP loaded with the cork extracts, showed that the presence of these extracts has no significant effect on the polymer mechanical performance. The results demonstrate the suitability of cork as a source of thermo-oxidative stabilizing additives for the formulation of polyolefins, and enable the exploitation of new routes of cork valorization.The authors are grateful to Amorim Cork Composites for providing the cork powder raw material. Ivo Aroso and Emanuel Fernandes are grateful for financial support of FCT through grants SFRH/BD/42273/2007 and SFRH/BPD/96197/2013, respectively. Funding was also granted from the European Union's Seventh Framework Programme (FP7/2007-2013) under grant agreement no REGPOT-CT2012-316331-POLARIS and from Project "Novel smart and biomimetic materials for innovative regenerative medicine approaches (Ref.: RL1-ABMR-NORTE-01-0124-FEDER-000016)" co-financed by North Portugal Regional Operational Programme (ON.2 - O Novo Norte), under the National Strategic Reference Framework (NSRF), through the European Regional Development Fund (ERDF)

Functionalized cork-polymer composites (CPC) by reactive extrusion using suberin and lignin from cork as coupling agents

High density polyethylene (HDPE) and cork powder were compounded in a co-rotating twin-screw extruder to obtain cork-polymer composites (CPC) with improved properties. Benzoyl peroxide (BPO) was used as initiator agent, and suberin or lignin isolated from cork enhanced filler-matrix bonding and promoted mechanical reinforcement with environmental benefits. The novel composites were characterised in terms of dimensional stability, evolution of morphology, thermal and mechanical properties and their performance was compared with that of composites containing polyethylene-grafted maleic anhydride (PE-g-MA) as coupling agent. As expected, composites with coupling agent present higher mechanical properties, lower water uptake and thickness swelling variation. Suberin acts as plasticizer with antioxidant benefits, while lignin works as a coupling agent, improving tensile modulus and maximum strength. Increasing lignin content does not improve the mechanical properties but improves thermal stability.The work was performed within the project of Corticeira Amorim S.G.P.S. on the development of new products based in/with cork. The authors gratefully acknowledge the financial support, through the COMPETE/QREN/EU funding program in the project with acronym NovelComp (QREN FCOMP-01-0202-FEDER-003107). The authors acknowledge the Portuguese Foundation for Science and Technology (FCT) and POPH/FSE for the doctoral Grants to E.M.F. (SFRH/BD/71561/2010) and I.M.A. (SFRH/BD/42273/2007)

Interaction of wine mannoproteins and arabinogalactans with anthocyanins

Wine polymeric material (WPM), which includes polysaccharides, proteins, and polyphenolic compounds, interacts with anthocyanins. To determine the contribution of polysaccharides in these interactions, the diffusion performance of anthocyanins along a dialysis membrane was determined in the presence and absence of isolated mannoproteins (MP) and arabinogalactans (AG) from WPM. Furthermore, to estimate the extent of the interaction between WPM and polyphenolic compounds, the activation energy (Ea) required for their diffusion in the presence of WPM was determined. AG, generally more abundant than MP in wine, interact in a greater extent with anthocyanins, showing their relevant contribution for WPM/anthocyanins interactions. The Ea for the diffusion of polyphenolic compounds in presence of WPM indicated the occurrence of interactions with relative weak to strong intensities (2.6–50.8 kJ/mol). As not all polyphenolic compounds were able to be released from WPM, stronger interactions, possibly by covalent linkages, are involved, providing new insights on WPM/polyphenolic compounds relationships.info:eu-repo/semantics/acceptedVersio

A Conceptual Image-Based Data Glove for Computer-Human Interaction

Data gloves are devices equipped with sensors that capture the movements of the hand of the user in order to select or manipulate objects in a virtual world. Data gloves were introduced three decades ago and since then have been used in many 3D interaction techniques. However, good data gloves are too expensive and only a few of them can perceive the full set of hand movements. In this paper we describe the design of an image-based data glove (IBDG) prototype suitable for finger sensible applications, like virtual objects manipulation and interaction approaches. The proposed device uses a camera to track visual markers at finger tips, and a software module tocompute the position of each finger tip and its joints in real-time. To evaluate our concept, we have built a prototype and tested it with 15 volunteers. We also discuss how to improve the engineering of the prototype, how to turn it into a low cost interaction device, as well as other relevant issues about this original concept