Improved hybrid method as a robust tool for reliability-based design optimization

In the engineering problems, the randomness and the uncertainties of the distribution of the structural parameters are a crucial problem. In the case of reliability-based design optimization (RBDO), it is the objective to play a dominant role in the structural optimization problem introducing the reliability concept. The RBDO problem is often formulated as a minimization of the initial structural cost under constraints imposed on the values of elemental reliability indices corresponding to various limit states. The classical RBDO leads to high computing time and weak convergence, but a Hybrid Method (HM) has been proposed to overcome these two drawbacks. As the hybrid method successfully reduces the computing time, we can increase the number of variables by introducing the standard deviations as optimization variables to minimize the error values in the probabilistic model. The efficiency of the hybrid method has been demonstrated on static and dynamic cases with extension to the variability of the probabilistic model. In this paper, we propose a modification on the formulation of the hybrid method to improve the optimal solutions. The proposed method is called, Improved Hybrid Method (IHM). The main benefit of this method is to improve the structure performance by much more minimizing the objective function than the hybrid method. It is also shown to demonstrate the optimality conditions. The improved hybrid method is next applied to two numerical examples, with consideration of the standard deviations as optimization variables (for linear and nonlinear distributions). When integrating the improved hybrid method within the probabilistic model variability, we minimize the objective function more and more.     

Removal of Basic Red 46 dye from aqueous solution by adsorption onto Moroccan clay

In this study, Moroccan crude clay of Safi, which was characterized by X-ray diffraction, is used as adsorbent for the investigation of the adsorption kinetics, isotherms and thermodynamic parameters of the Basic Red 46 (BR46) in aqueous solutions at various dye concentrations, adsorbent masses and pH values. The results showed that the adsorption capacity of the dye increased by initial dye concentration and pH values. Two kinetic models (the pseudo-first-order and the pseudo-second-order) were used to calculate the adsorption rate constants. The adsorption kinetics of the basic dye followed pseudo-second-order model. The experimental data isotherms were analyzed using the Langmuir, Freundlich and Dubinin–Radushkevish equations. The monolayer adsorption capacity for BR46 dye is 54 mg/g of crude clay. Nearly 20 min of contact time was found to be sufficient for the dye adsorption to reach equilibrium. Thermodynamical parameters were also evaluated for the dye–adsorbent system and revealed that the adsorption process is exothermic in nature.     

Simulation of a high temperature electrolyzer

Based on Solid Oxide Fuel Cell (SOFC) technology, Solid Oxide Electrolysis Cell (SOEC) offers an interesting solution for mass hydrogen production. This study proposes a multiphysics model to predict the SOEC behavior, based on similar charge, mass, and heat transport phenomena as for SOFC. However, the mechanism of water steam reduction on Nickel/Yttria-Stabilized Zirconia (Ni/YSZ) cermet is not yet clearly identified. Therefore, a global approach is used for modeling. The simulated results demonstrated that a Butler–Volmer’s equation including concentration overpotential provides an acceptable estimation of the experimental electric performance under some operating conditions. These simulations highlighted three thermal operating modes of SOEC and showed that temperature distribution depends on gas feeding configurations.     

New Scattering Matrix Model for Modeling Ferrite Media Using the TLM Method

This paper aims to extend the transmission line matrix method with a hybrid symmetrical condensed node (HSCN) to model ferrite media in the time domain. To take into account the anisotropy and dispersive properties of ferrite media, equivalent current sources are incorporated into supplementary stubs of the original HSCN. The scattering matrix of the proposed HSCN is provided, and the validity of this approach is demonstrated for both transversely and longitudinally magnetized ferrites. Agreement is achieved between the results of this approach and those of the theoretical and the finite‐difference time‐domain method.     

Methodology for integrated management system improvement: combining costs deployment and value stream mapping

Integrated Management System – Quality, Environment, Safety (IMS-QES) combines all related components of a business into one system for easier management and operations Quality (QMS/ISO 9001), Environmental (EMS/ISO 14001), and Health & Safety (OHSAS 18001). IMS-QES has been generally used to increase operational performance in manufacturing systems. However, the economic impact of standard approach of IMS-QES remains difficult due to the lack of alignment between IMS-QES objectives and strategic management of the company (policy of IMS-QES) and also the inadequacy between the improvement processes and the cost of losses.

Therefore, the main objective of this work is to overcome this limitation. The Framework proposed approach called IM-VCF integrates concepts from IMS-QES, Value Stream Mapping and Cost Deployment tool. It is structured in ten steps. It allows a company to assure proper alignment between IMS-QES policy and business operations and identify the categories of losses. IM-VCF allows analysing critical issues and estimating the potential savings, in terms of cost. A case study taken from the application of the IM-VSF within certified QSE chemical fertiliser port is presented.     

A robust study of reliability-based optimization methods under eigen-frequency

Nowadays, the search in reliability-based design optimization is becoming an important engineering design activity. Traditionally for these problems, the objective function is to minimize a cost function while satisfying the reliability constraints. The reliability constraints are usually formulated as constraints on the probability of failure. This paper focuses on the study of a particular problem with the failure mode on vibration of structure. The difficulty in evaluating reliability constraints comes from the fact that modern reliability analysis methods are themselves formulated as an optimization problem. Solving such nested optimization problems is extremely expensive for large-scale multidisciplinary systems which are likewise computationally intensive. With this in mind research, we propose in this paper a new method to treat reliability-based optimization methods under frequencies constraint. The goal of this development has resolved just one problem of optimization and reduced the cost of computation. Aircraft wing design typically involves multiple disciplines such as aerodynamics and structure; this numerical example demonstrated the different advantages of the proposed method.