Turning ability analysis of a fully appended twin screw vessel by CFD. Part II: Single vs. twin rudder configuration

In the present paper, the analysis of the turning capability of the naval supply vessel presented in Part I (Broglia et al., 2015) is continued with different stern appendages, namely twin rudder and centreline skeg. The main purpose of the analysis is to assess the capability of an in-house CFD tool in capturing the different manoeuvring characteristics of the ship hulls; the test case is challenging, as the difference be- tween the two configurations lies in the complex flow structure related to rudder-propeller interactions. Moreover, although the twin rudder solution slightly improves the

Thwarting Obfuscated Malware via Differential Fault Analysis

Detecting malware in mobile applications has become increasingly complex as malware developers turn to advanced techniques to hide or obfuscate malicious components. Alterdroid is a dynamic-analysis tool that compares the behavioral differences between an original app and numerous automatically generated versions of it containing carefully injected modifications.

Endothelial shear stress from large-scale blood flow simulations

We discuss the optimal evaluation of endothelial shear stress for real-life case studies based on anatomic data acquisition. The fluid dynamic simulations require smoothing of the geometric dataset to avoid major artefacts in the flow patterns, especially in the proximity of bifurcations. A systematic series of simulations at different corrugation levels shows that, below a smoothing length of about 0.5 mm, the numerical data are insensitive to further smoothing. © 2011 The Royal Society.

Risk assessment of atherosclerotic plaques based on global biomechanics

We present the results of a computational study of the entire left coronary system simulated both at Newtonian level and at red blood cell resolution for a sizeable number of physiological conditions. We analyze the cardiovascular implications of stenotic plaques and show that the standard clinical criterion for surgical or percutaneous intervention, based on the fractional flow reserve (FFR), is significantly affected by system-dependent, local hemodynamic factors.

Petaflop biofluidics simulations on a two million-core system

We present a computational framework for multi-scale simulations of real-life biofluidic problems. The framework allows to simulate suspensions composed by hundreds of millions of bodies interacting with each other and with a surrounding fluid in complex geometries. We apply the methodology to the simulation of blood flow through the human coronary arteries with a spatial resolution comparable with the size of red blood cells, and physiological levels of hematocrit (the red blood cell volume fraction).

A Fast Algorithm to Solve Nonlinear Hypersingular Integral Equations Arising in a Crack Problem

A fast algorithm related to the generalized minimal residual algorithm (GMRES) is proposed to approximate solution of a nonlinear hypersingular integral equation arising in a crack problem. At first, a collocation method is proposed and developed in weighted Sobolev space. Then, the Newton-Kantorovjch method is used for solving the obtained system of nonlinear equations.

Merging GPS and Atmospherically Corrected InSAR Data to Map 3-D Terrain Displacement Velocity

A method to derive accurate spatially dense maps of 3-D terrain displacement velocity is presented. It is based on the merging of terrain displacement velocities estimated by time series of interferometric synthetic aperture radar (InSAR) data acquired along ascending and descending orbits and repeated GPS measurements. The method uses selected persistent scatterers (PSs) and GPS measurements of the horizontal velocity. An important step of the proposed method is the mitigation of the impact of atmospheric phase delay in InSAR data.

AntiCheetah: Trustworthy computing in an outsourced (cheating) environment

The increasing need for performing expensive computations has motivated outsourced computing, as in crowdsourced applications leveraging worker cloud nodes. However, these outsourced computing nodes can potentially misbehave or fail. Exploiting the redundancy of nodes can help guaranteeing correctness and availability of results. This entails that reliable distributed computing can be achieved at the expense of convenience.

Numerical methods for pricing options under stochastic volatility models.

Partial integro-differential equation (PIDE) formulations are often preferable for pricing options under models with stochastic volatility and jumps. In this talk, we consider the numerical approximation of such models. On one hand, due to the non-local nature of the integral term, we propose to use Implicit-Explicit (IMEX) Runge-Kutta methods for the time integration to solve the integral term explicitly, giving higher order accuracy schemes under weak stability time-step restrictions.