Τμήμα Μαθηματικών και Στατιστικής / Department of Mathematics and Statistics: Recent submissions
Now showing items 21-40 of 1633
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Article
A nonequilibrium thermodynamics perspective of thixotropy
(2018)We propose a new description of elasto-viscoplastic fluids by relating the notion of thixotropy directly to internal viscoelasticity and network structures through a general, thermodynamically consistent approach. By means ...
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Article
Blue Energy Potential Analysis in the Mediterranean
(2019)This paper describes the status of the potential of blue energy in the Mediterranean region, with focus on the region around Cyprus. Previous studies are reviewed, the main findings of the blue energy potential analysis ...
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Article
Determining true material constants of viscoplastic materials from rotational rheometer data
(2018)We analyse the circular Couette flow of Herschel–Bulkley fluids to investigate the validity of the assumption that the rate of strain distributions across the gap share a common point. It is demonstrated that this is true ...
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Article
Viscoplastic Couette Flow in the Presence of Wall Slip with Non-Zero Slip Yield Stress
(2019)The steady-state Couette flow of a yield-stress material obeying the Bingham-plastic constitutive equation is analyzed assuming that slip occurs when the wall shear stress exceeds a threshold value, the slip (or sliding) ...
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Article
Annular pressure-driven flow of a Bingham plastic with pressure-dependent rheological parameters
(2019)The pressure and temperature dependence of the yield stress is well established in oil drilling. In the present work, the steady, annular pressure-driven flow of a Bingham plastic is considered under the assumption that ...
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Article
Start-up plane Poiseuille flow of a Bingham fluid
(2019)The start-up flow of a Bingham plastic in a channel is considered and Safronchik’s solution [1] for the initial evolution of the yield surface and the core velocity is revisited. Stricter time bounds for the validity of ...
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Article
Pressure-driven flow of a Herschel-Bulkley fluid with pressure-dependent rheological parameters
(2018)The lubrication flow of a Herschel-Bulkley fluid in a symmetric long channel of varying width, 2h(x), is modeled extending the approach proposed by Fusi et al. [“Pressure-driven lubrication flow of a Bingham fluid in a ...
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Article
Lubrication solution of the axisymmetric Poiseuille flow of a Bingham fluid with pressure-dependent rheological parameters
(2018)The lubrication flow of a Bingham plastic in long tubes is modeled using the approach proposed by Fusi and Farina (Appl. Math. Comp. 320, 1–15 (2018)). Both the plastic viscosity and the yield stress are assumed to vary ...
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Article
Analytical solution of the flow of a Newtonian fluid with pressure-dependent viscosity in a rectangular duct
(2018)We derive a fully analytical solution for the steady flow of an isothermal Newtonian fluid with pressure-dependent viscosity in a rectangular duct. The analytical solution for the governing equations is exact (based on the ...
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Article
Axisymmetric Poiseuille flow of a Bingham plastic with rheological parameters varying linearly with pressure
(2018)We consider the steady axisymmetric Poiseuille flow of a Bingham plastic under the assumption that both the plastic viscosity and the yield stress vary linearly with pressure. An analytical solution is derived for the case ...
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Article
Newtonian Poiseuille flow in ducts of annular-sector cross-sections with Navier slip
(2018)We consider the Newtonian Poiseuille flow in a duct the cross section of which is either a circular or an annular sector assuming that Navier slip occurs either along both the cylindrical walls or only along the outer ...
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Article
The PAL (Penalized Augmented Lagrangian) method for computing viscoplastic flows: A new fast converging scheme
(2018)Computation of viscoplastic fluid flows has always been a challenging task. Viscoplastic models are intrinsically discontinuous at the yielded-unyielded interface, which leads to numerical difficulties, because of the ...
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Article
Unbiased Monte Carlo: Posterior estimation for intractable/infinite-dimensional models
(2018)We provide a general methodology for unbiased estimation for intractable stochastic models. We consider situations where the target distribution can be written as an appropriate limit of distributions, and where conventional ...
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Article
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Book Chapter
Posterior Contraction in Bayesian Inverse Problems Under Gaussian Priors
(Springer International Publishing, 2018)We study Bayesian inference in statistical linear inverse problems with Gaussian noise and priors in a separable Hilbert space setting. We focus our interest on the posterior contraction rate in the small noise limit, under ...
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Article
Sparsity-promoting and edge-preserving maximum a posteriori estimators in non-parametric Bayesian inverse problems
(2018)We consider the inverse problem of recovering an unknown functional parameter in a separable Banach space, from a noisy observation vector of its image through a known possibly non-linear map . We adopt a Bayesian approach ...
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Article
On the regularity of the non-dynamic parabolic fractional obstacle problem
(2018)In the class of the non-dynamic Fractional Obstacle Problems of parabolic type, it is shown existence, uniqueness, apriori bounds of the solution and optimal regularity of the space derivatives of the solution. Furthermore, ...
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Article
The heat trace for the drifting laplacian and schrodinger operators on manifolds
(2019)We study the heat trace for both Schrodinger operators as well as the drifting Laplacian on compact Riemannian manifolds. In the case of a finite regularity (bounded and measurable) potential or weight function, we prove ...
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Article
The spectrum of continuously perturbed operators and the Laplacian on forms
(2019)In this article we study the variation in the spectrum of a self-adjoint nonnegative operator on a Hilbert space under continuous perturbations of the operator. In the particular case of the Laplacian on k-forms over a ...
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Article
The spectrum of the Laplacian on forms over flat manifolds
(2019)In this article we prove that the spectrum of the Laplacian on k-forms over a non compact flat manifold is always a connected closed interval of the non negative real line. The proof is based on a detailed decomposition ...