Browsing by Author "Pavlidis, Dimitrios"
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Item Open Access Multispectral image analysis approach to detect adulteration of beef and pork in raw meats(Elsevier, 2019-08-08) Ropodi, Athina; Pavlidis, Dimitrios; Mohareb, Fady R.; Panagou, Efstathios; Nychas, GeorgeThe aim of this study was to investigate the potential of multispectral imaging supported by multivariate data analysis for the detection of minced beef fraudulently substituted with pork and vice versa. Multispectral images in 18 different wavelengths of 220 meat samples in total from four independent experiments (55 samples per experiment) were acquired for this work. The appropriate amount of beef and pork-minced meat was mixed in order to achieve nine different proportions of adulteration and two categories of pure pork and beef. After an image processing step, data from the first three experiments were used for partial least squares-discriminant analysis (PLS-DA) and linear discriminant analysis (LDA) so as to discriminate among all adulteration classes, as well as among adulterated, pure beef and pure pork samples. Results showed very good discrimination between pure and adulterated samples, for PLS-DA and LDA, yielding 98.48% overall correct classification. Additionally, 98.48% and 96.97% of the samples were classified within a ± 10% category of adulteration for LDA and PLS-DA respectively. Lastly, the models were further validated using the data of the fourth experiment for independent testing, where all pure and adulterated samples were classified correctly in the case of PLS-DA, while LDA was proved to be less accurate.Item Open Access A three-phase interpenetrating continua approach for wave and porous structure interaction(Emerald, 2020-05-14) Yang, Liang; Buchan, Andrew; Pavlidis, Dimitrios; Jones, Alan; Smith, Paul; Sakai, Mikio; Pain, ChristopherA three phase interpenetrating continua model for the numerical simulation of water waves and porous structure interaction is proposed in this work. In contrast with one-fluid formulation/multi-component methods, each phase has its own characteristics, density, velocity, etc and each point is occupied by all phases, this model requires additional closure laws to describe the interfacial momentum exchange, e.g., via the Ergun's equation. First, the porous structure is modelled as a phase of continua with a penalty force adding on the momentum equation, so the conservation of mass is guaranteed without source terms. Second, the adaptive unstructured mesh modelling with P1DG-P1 elements is employed here to decrease the total number of degree of freedom maintaining the same order of accuracy. Several benchmark problems are used to validate the model, which includes the darcy flow, classical collapse of water column and water column with a porous structure.