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    ABSTRACT: Ice pigging is a process used by many industries for pipe cleaning and product recovery. Ice slurries, used to form an ice pig, are generated using an aqueous solution of water and a freezing point depressant, typically salt (NaCl) at 5% salinity. The ‘thickness’ of an ice slurry is key to the ice pig’s performance, and this paper investigates a new non-invasive method of ice fraction measurement. Electromagnetic (EM) waves, with a frequency of 2.5GHz, are absorbed rapidly by water molecules, but pass through ice with little drop in intensity, due to key differences in the materials’ atomic structures. This phenomenon is exploited, and results show ice fraction can be approximated to within ± 1.2% using a VNA spectrum analyser, then mathematical manipulation and analysis. This rivals the error in calorimetry, ± 1.3%, which currently seen as the ‘gold standard’ in ice fraction measurement across the industry.
    No preview · Article · Jul 2014 · International Journal of Refrigeration
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    ABSTRACT: In this paper we present a novel approach to the problem of steganography detection in JPEG images by applying a statistical attack. The method is based on the empirical Benford's Law and, more specifically, on its generalized form. We prove and extend the validity of the logarithmic rule in colour images and introduce a blind steganographic method which can flag a file as a suspicious stego-carrier. The proposed method achieves very high accuracy and speed and is based on the distributions of the first digits of the quantized Discrete Cosine Transform coefficients present in JPEGs. In order to validate and evaluate our algorithm, we developed steganographic tools which are able to analyse image files and we subsequently applied them on the popular Uncompressed Colour Image Database. Furthermore, we demonstrate that not only can our method detect steganography but, if certain criteria are met, it can also reveal which steganographic algorithm was used to embed data in a JPEG file.
    Full-text · Article · Feb 2013 · Digital Investigation
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    ABSTRACT: The GTN continuous damage model is very popular in academia and industry for structural integrity assessment and ductile fracture simulation. Following Aravas’ influential 1987 paper, Newton’s method has been used widely to solve the GTN equations. However, if the starting point is far from the solution, then Newton’s method can fail to converge. Hybrid methods are preferred in such cases. In this work we translate the GTN equations into a non-linear minimization problem and then apply the Levenberg–Marquardt and Powell’s ‘dogleg’ hybrid methods to solve it. The methods are tested for accuracy and robustness on two simple single finite element models and two 3D models with complex deformation paths. In total nearly 137,000 different GTN problems were solved. We show that the Levenberg–Marquardt method is more robust than Powell’s method. Our results are verified against the Abaqus’ own solver. The superior accuracy of the Levenberg–Marquardt method allows for larger time increments in implicit time integration schemes.
    No preview · Article · Sep 2012 · Computer Methods in Applied Mechanics and Engineering
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Wireless Personal Communications 12/2013; 73(3). DOI:10.1007/s11277-013-1250-5
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16th Annual Conference of the International Association for Mathematical Geosciences, October 2014, New Delhi, India; 10/2014
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