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Nicolay P.,Carinthian Technology Research AG | Aubert T.,University of Savoy
IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control | Year: 2013

The design of wireless SAW sensors for hightemperature applications requires accurate knowledge of the constitutive materials' physical properties in the desired temperature range. In particular, it is crucial to use reliable temperature coefficients of the stiffness, piezoelectric, dielectric, and expansion constants of the propagation medium to achieve correct simulations of the considered devices. Currently, the best-suited piezoelectric material for high-temperature SAW applications is langasite (LGS). Unfortunately, the available coefficients do not allow for precise prediction of the temperature dependence of LGS-based SAW devices above 300°C. A novel method, based on a simulated annealing algorithm coupled with a Rayleigh wave simulation program, was developed to find optimal LGS temperature coefficients. This approach has proven to yield accurate results up to at least 800°C. © 2013 IEEE.

McGunnigle G.,Carinthian Technology Research AG
Journal of the Optical Society of America A: Optics and Image Science, and Vision | Year: 2010

We propose a system to detect wet surfaces using near infrared LED lighting and a conventional CCD camera. There is a sharp fall in the transmission of light through water for wavelengths longer than 920 nm. By detecting this transition it is possible to robustly detect a film of water lying on a surface. This paper considers surfaces that are impermeable, are not hydrophilic, and are sufficiently reflective (reflectivity, p>0.4). A system is demonstrated that can detect water on a wide range of surfaces that meet these conditions. © 2010 Optical Society of America.

McGunnigle G.,Carinthian Technology Research AG
Journal of the Optical Society of America A: Optics and Image Science, and Vision | Year: 2010

A photometric stereo technique is proposed that uses four extended sources and specular reflection to estimate surface topography. It is shown that if the intensity of incident light is weighted according to its zenith angle, then the radiance of surface facets will vary linearly with their slope. A simple system that approximates this lighting distribution is demonstrated. It is shown that surface slope in the range [-0.5,0.5] can be recovered to within a multiplicative constant. © 2010 Optical Society of America.

Buchegger W.,Vienna University of Technology | Wagner C.,Vienna University of Technology | Lendl B.,Vienna University of Technology | Kraft M.,Carinthian Technology Research AG | Vellekoop M.J.,Vienna University of Technology
Microfluidics and Nanofluidics | Year: 2011

We present a horizontal multi-lamination micromixer with specially wedge shaped vertical fluid inlets for fast and highly uniform fluid mixing in the low millisecond range. The four-layer laminar flow is created by a fluidic distribution network, reducing the amount of fluid connectors to the macroscopic world to two. All the geometries of the channel inlets and the distribution network were optimized for low flow rates and hence for low sample consumption using CFD simulations. The device materials applied feature low absorption in the mid-infrared (wavelength 3-10 urn) allowing to use this device for time resolved infrared spectroscopy. The micromixer itself can be built by silicon micromachining techniques without the need of complicated fabrication steps. Due to a transparent calcium fluoride cover optical measurements are possible as well which were used to characterize the device. Mixing times in the range of 1 ms with optical color measurements of aqueous solutions and with time resolved infrared measurement of the proton exchange reaction of H2O and D2O are achieved. © Springer-Verlag 2010.

McGunnigle G.,Carinthian Technology Research AG | Dong J.,Ocean University of China
IET Computer Vision | Year: 2011

The authors propose a new photometric stereo (PS) method that augments a conventional four-light approach with coaxial illumination. The new method is based on a four-light, leave-one-out approach: the authors argue that coaxial lighting improves robustness to shadowing and specular highlights. The authors also specify a method to detect pixels that are shadowed or that do not conform to Lambert's law. The approach is tested on cylinders of various materials. The authors found that for dielectrics the method gave reliable results for gradients in the range -2 to 2. The results lead them to conclude that coaxial illumination makes PS more robust to shadow and specularity. © 2011 The Institution of Engineering and Technology.

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