An integrated toolchain for model based functional safety analysis

The significant increase in the complexity and autonomy of the hardware systems renders the verification of the functional safety of each individual component as well as of the entire system a complex task and underlines the need for integrated, model based tools that would assist this process. In this paper the authors present such a tool, coupled with an approach to functional safety analysis, based on the integration of functional tests into the model itself. The analysis of the resulting model is done through a stochastic Bayesian model. This approach strives to both bypass the necessity for costly hardware testing and integrate the functional safety analysis into an intuitive component development process.     

Bayesian prediction of crack growth based on a hierarchical diffusion model

A general Bayesian approach for stochastic versions of deterministic growth models is presented to provide predictions for crack propagation in an early stage of the growth process. To improve the prediction, the information of other crack growth processes is used in a hierarchical (mixed‐effects) model. Two stochastic versions of a deterministic growth model are compared. One is a nonlinear regression setup where the trajectory is assumed to be the solution of an ordinary differential equation with additive errors. The other is a diffusion model defined by a stochastic differential equation where increments have additive errors. While Bayesian prediction is known for hierarchical models based on nonlinear regression, we propose a new Bayesian prediction method for hierarchical diffusion models. Six growth models for each of the two approaches are compared with respect to their ability to predict the crack propagation in a large data example. Surprisingly, the stochastic differential equation approach has no advantage concerning the prediction compared with the nonlinear regression setup, although the diffusion model seems more appropriate for crack growth. Copyright © 2016 John Wiley & Sons, Ltd.     

Efficient determination of some potentially toxic metal ions from real samples via modified nano-γ-alumina-based solid-phase extraction followed by flame atomic absorption spectrometric analysis

In the current research work, trace amounts of the Ni(II), Cu(II), Ag(I) and Zn(II) ions in water, cabbage and pomegranate juice were determined via the solid-phase extraction approach based on a new selective adsorbent in the continuous mode followed by flame atomic absorption spectrometry. This efficient and safe sorbent was easily prepared from the immobilisation of 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-BrPADAP), as a selective chelating agent, onto nano-γ-alumina coated with sodium dodecyl sulphate. Nano-γ-alumina was successfully synthesised by the solution combustion procedure and was subsequently analysed by various techniques including SEM, XRD and BET. The parameters involved in the metal ions extraction including the sample pH and volume, amount of sorbent, flow rates of the sample and the eluent, and type and concentration of the eluting agent were optimised. Under the optimal operating conditions, the proposed sample preparation method provided the good linear dynamic ranges (LDRs) 6–300, 4–300, 4–110 and 4–300 µg L^?1 for the Ni(II), Cu(II), Ag(I) and Zn(II) ions, respectively, with the correlation of determinations (R²s) higher than 0.99. The detection limit (LOD) and repeatability (RSD%) values (n = 8) obtained were found to be in the ranges of 1.50–2.00 µg L^?1 and 4.44–5.52%, respectively. The calculated enrichment factors were found to be 166.6, 166.6, 200 and 200 for the Cu(II), Ag(I), Ni(II) and Zn(II) ions, respectively. According to the adsorption studies, the Freundlich isotherm and the pseudo-second-order model showed reasonable fits to the experimental data. Also, thermodynamic studies demonstrated that the adsorption process was spontaneous and exothermic.     

Enforcing dissipative entanglement by feedback

We study the possibility of enhancing the stationary entanglement achievable with two-qubit dissipating into a common environment by means of feedback. We contrast the effect of Markovian with Bayesian feedback and show that, depending on the initial state, the performance of the latter is from 16% to 33% superior.     

Using degradation models to assess pipeline life

Longitudinal inspections of thickness at particular locations along a pipeline provide useful information to assess the remaining life of the pipeline. In applications with different mechanisms of corrosion processes, we have observed various types of general degradation paths. We present two applications of fitting a degradation model to describe the corrosion initiation and growth behavior in a pipeline. We use a Bayesian approach for parameter estimation for the degradation model. The failure‐time and remaining lifetime distributions are derived from the degradation model, and we compute Bayesian estimates and credible intervals of the failure‐time and remaining lifetime distributions for both individual segments and for the entire pipeline circuit.     

Real-time Bayesian data assimilation with data selection,correction of model bias,and on-the-fly uncertainty propagation

The work introduces new advanced numerical tools for data assimilation in structural mechanics. Considering the general Bayesian inference context, the proposed approach performs real-time and robust sequential updating of selected parameters of a numerical model from noisy measurements, so that accurate predictions on outputs of interest can be made from the numerical simulator. The approach leans on the joint use of Transport Map sampling and PGD model reduction into the Bayesian framework. In addition, a procedure for the dynamical and data-based correction of model bias during the sequential Bayesian inference is set up, and a procedure based on sensitivity analysis is proposed for the selection of the most relevant data among a large set of data, as encountered for instance with full-field measurements coming from digital image/volume correlation (DIC/DVC) technologies. The performance of the overall numerical strategy is illustrated on a specific example addressing structural integrity on damageable concrete structures, and dealing with the prediction of crack propagation from a damage model and DIC experimental data.     

Game theoretic analysis of negotiations under bankruptcy

We extend the contingent claims framework for the levered firm in explicitly modelling the resolution of financial distress under formal bankruptcy as a non-cooperative game between claimants under the supervision of the bankruptcy judge. The identity of the class of claimants proposing the first reorganization plan is found to be a key determinant of the time spent under bankruptcy, the likelihood of liquidation and the renegotiated value of claims. Our quantitative results confirm the economic intuition that a bankruptcy design must trade-off the initial priority of claims with the viability of reorganized firms.     

A class of exhaustive cone splitting procedures in conical algorithms for concave minmization

A class of exhaustive cone splitting procedures is developed and is shown to perform substantially better than the bisection procedure in conical algorithms for concave minimization. Computational experiments are reported and discussed.     

An implicit high-order preconditioned flux reconstruction method for low-Mach-number flow simulation with dynamic meshes

A fully implicit high-order preconditioned flux reconstruction/correction procedure via reconstruction (FR/CPR) method is developed to solve the compressible Navier-Stokes equations at low Mach numbers. A dual-time stepping approach with the second-order backward differentiation formula (BDF2) is employed to ensure temporal accuracy for unsteady flow simulation. When dynamic meshes are used to handle moving/deforming domains, the geometric conservation law is implicitly enforced to eliminate errors due to the resolution discrepancy between BDF2 and the spatial FR/CPR discretization. The large linear system resulted from the spatial and temporal discretizations is tackled with the restarted generalized minimal residual solver in the PETSc (portable, extensible toolkit for scientific computation) library. Through several benchmark steady and unsteady numerical tests, the preconditioned FR/CPR methods have demonstrated good convergence and accuracy for simulating flows at low Mach numbers. The new flow solver is then used to study the effects of Mach number on unsteady force generation over a plunging airfoil when operating in low-Mach-number flows. It is observed that weak compressibility has a significant impact on thrust generation but has a negligible effect on lift generation of an oscillating airfoil.     

Partition Weighted Approach For Estimating the Marginal Posterior Density With Applications

The computation of marginal posterior density in Bayesian analysis is essential in that it can provide complete information about parameters of interest. Furthermore, the marginal posterior density can be used for computing Bayes factors, posterior model probabilities, and diagnostic measures. The conditional marginal density estimator (CMDE) is theoretically the best for marginal density estimation but requires the closed-form expression of the conditional posterior density, which is often not available in many applications. We develop the partition weighted marginal density estimator (PWMDE) to realize the CMDE. This unbiased estimator requires only a single Markov chain Monte Carlo output from the joint posterior distribution and the known unnormalized posterior density. The theoretical properties and various applications of the PWMDE are examined in detail. The PWMDE method is also extended to the estimation of conditional posterior densities. We carry out simulation studies to investigate the empirical performance of the PWMDE and further demonstrate the desirable features of the proposed method with two real data sets from a study of dissociative identity disorder patients and a prostate cancer study, respectively. Supplementary materials for this article are available online.