Corrosion of NiTi Wires with Cracked Oxide Layer

Corrosion behavior of superelastic NiTi shape memory alloy wires with cracked TiO₂ surface oxide layers was investigated by electrochemical corrosion tests (Electrochemical Impedance Spectroscopy, Open Circuit Potential, and Potentiodynamic Polarization) on wires bent into U-shapes of various bending radii. Cracks within the oxide on the surface of the bent wires were observed by FIB–SEM and TEM methods. The density and width of the surface oxide cracks dramatically increase with decreasing bending radius. The results of electrochemical experiments consistently show that corrosion properties of NiTi wires with cracked oxide layers (static load keeps the cracks opened) are inferior compared to the corrosion properties of the straight NiTi wires covered by virgin uncracked oxides. Out of the three methods employed, the Electrochemical Impedance Spectroscopy seems to be the most appropriate test for the electrochemical characterization of the cracked oxide layers, since the impedance curves (Nyquist plot) of differently bent NiTi wires can be associated with increasing state of the surface cracking and since the NiTi wires are exposed to similar conditions as the surfaces of NiTi implants in human body. On the other hand, the potentiodynamic polarization test accelerates the corrosion processes and provides clear evidence that the corrosion resistance of bent superelastic NiTi wires degrades with oxide cracking.     

Structural design of carbon/epoxy bio‐inspired wind turbine blade using fluid/structure simulation

The purpose of this paper is to present the structural design procedure of a low‐speed, horizontal axis, bio‐inspired wind turbine blade made of carbon/epoxy. The methodology initiates with the mechanical characterization of the carbon fiber composite material. An aerodynamic simulation using Computational Fluid Dynamics (CFD) method is performed in order to obtain the pressure distribution profile of the blade. This result is coupled with a Finite Element Analysis (FEA) to carry out an iterative design process through a Fluid‐Structure Interaction (FSI) simulation. Different stacking sequences of laminates are evaluated to find a configuration which allows balance between aerodynamic and dynamic inertial loads, ensuring an almost undeformed geometry during wind turbine's operation. The final structural design of the blade consists in six regions with different laminates. These are balanced and symmetric with distinct thickness characteristics and stacking sequences, which vary in three different orientations: 0^°, ± 45^° and 90^°, achieving a minimum deflection at the tip close to 3.11 cm, and a total weight of 3.6 kg of a 1.8 m radius blade, even with the restrictions imposed by the non‐conventional geometry. Copyright © 2016 John Wiley & Sons, Ltd.     

Influence of depth and geological structure on the transmission of blast vibrations

Vibrations generated by blasting carried out during the quarrying of material induce dynamic stresses that can give rise to damage of diverse considerations in surrounding buildings and structures. The adverse effects of vibrations caused by explosives used in mining and civil works can be controlled by suitably planning blasting operations, appropriately managing and optimising the equipment used, and monitoring the processes that cause these vibrations. The aims of the present study were to discuss and test the existence of a damping of underground vibrations, besides defining a transmission law for such vibrations which will depend on the directionality between the blast and the measurement point. Besides, the damages that vibrations can produce on the rock mass are evaluated. Their effects are very similar to those produced by an earthquake that disconnects the rock mass integral blocks.     

Analysis of medications change in Parkinson’s disease progression data

Parkinson’s disease is a neurodegenerative disorder that affects people worldwide. Careful management of patient’s condition is crucial to ensure the patient’s independence and quality of life. This is achieved by personalized treatment based on individual patient’s symptoms and medical history. The aim of this study is to determine patient groups with similar disease progression patterns coupled with patterns of medications change that lead to the improvement or decline of patients’ quality of life symptoms. To this end, this paper proposes a new methodology for clustering of short time series of patients’ symptoms and prescribed medications data, and time sequence data analysis using skip-grams to monitor disease progression. The results demonstrate that motor and autonomic symptoms are the most informative for evaluating the quality of life of Parkinson’s disease patients. We show that Parkinson’s disease patients can be divided into clusters ordered in accordance with the severity of their symptoms. By following the evolution of symptoms for each patient separately, we were able to determine patterns of medications change which can lead to the improvement or worsening of the patients’ quality of life.     

CEL gyroscope with injected squeezed vacuum

It is shown that the injection of a squeezed vacuum into a correlated emission ring laser gyroscope enhances the sensitivity of the device. In particular, it is demonstrated that if the phase of the injected squeezed vacuum is chosen appropriately, then the output is squeezed in the phase quadrature. This may lead to complete suppression of the shot noise in the signal.     

Preparation and characterization of β‐cyclodextrin‐linked chitosan microparticles

Hydrophobically modified chitosan containing β‐cyclodextrin (CD) units was synthesized by using tosylated β‐CD. The final product was characterized by Fourier transform infrared (FTIR) spectroscopy, elemental analysis and TGA, and rheometry. The polymer bearing β‐CD moieties was used to obtain crosslinked microparticles by spray‐drying which could then be used in a controlled release system for drugs. FTIR confirmed the formation of an amide linkage between cyclodextrin and chitosan. As fluorescence spectroscopy demonstrated, hydrophobic microenvironments were formed by chitosan bearing cyclodextrin in solution at lower concentrations than for chitosan. Rheometry and FTIR showed the crosslinking of the new polymer using genipin, a molecule of natural origin. Microspheres (MS) obtained by spray‐drying showed narrow size distribution when β‐CD was grafted onto chitosan and ξ‐potential of MS was slightly lower although it remained positive. In conclusion, β‐CD linked chitosan polymer can be considered as a very promising controlled drug delivery system for drugs. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Privacy protection vs. utility in visual data

Multimedia Tools and Applications - Ubiquitous and networked sensors impose a huge challenge for privacy protection which has become an emerging problem of modern society. Protecting the privacy of...