3D Modeling of the Elastic-Plastic Behavior of Thin Aeronautical Adhesive Films Suited for a Wide Range of Tensile/Compression-Shear Loads

Adhesive bonding is an interesting structural assembling technique for weight saving in modern commercial aircraft, in which the use of composites materials is increasing. In order to meet both optimization and respect of safety conception constraints, the development of accurate numerical strategies is required. Thus, improvement in the experimental characterization and in the design of reliable numerical tools for bonded assemblies is necessary. This paper presents the characterization of the elastic-plastic behaviour of four aeronautical adhesive films, consisting of two epoxy-based resins supported by two types of carrier. The characterization over a wide range of monotonic proportional tensile-shear loads is performed using a modified Arcan test device designed to strongly limit the influence of edge effects. Moreover, to obtain an accurate definition of the initial elastic limit of the adhesives, further experimental tests have been performed using a pressure vessel especially designed to study the influence of the hydrostatic stress. Inverse identification techniques using finite element analysis have been used to identify the material parameters of an elastic-plastic model based on the experimental results (the load-displacement curves). Results underline the potential of such a model to represent the non-linear behaviour of ductile adhesives under tensile/compression-shear proportional monotonic loads.     

An artificial intelligence approach for fuzzy possibilistic-stochastic multi-objective logistics network design

In this paper, a logistics network is investigated which includes multi-suppliers, collection centers, transfer stations, treatment stations, and products. For this purpose, a multi-objective mathematical programming model is proposed that minimizes the total costs including the fixed costs for opening facilities and transportation costs between facilities, minimizes the distance between each waste-generating facilities and transfer stations, maximizing the distance between treatment and disposal stations and customer zones, and maximizes the sum of the reliability of coverage for the potential facilities which will be open. In order to make the results of this paper more realistic, a case study in the iron and steel industry has been investigated. Besides, a new solution approach is proposed by combining fuzzy possibilistic programming, stochastic programming, and fuzzy multi-objective programming. Moreover, an imperialist competitive algorithm is proposed to obtain near optimal solution in comparison with other evolutionary algorithms. Finally, computational experiments are provided to demonstrate the applicability and suitability of the proposed model and solution approaches.     

Simultaneous production of two types of synthesis gas by steam and tri‐reforming of methane using an integrated thermally coupled reactor: mathematical modeling

In this work, tri‐reforming and steam reforming processes have been coupled thermally together in a reactor for production of two types of synthesis gases. A multitubular reactor with 184 two‐concentric‐tubes has been proposed for coupling reactions of tri‐reforming and steam reforming of methane. Tri‐reforming reactions occur in outer tube side of the two‐concentric‐tube reactor and generate the needed energy for inner tube side, where steam reforming process is taking place. The cocurrent mode is investigated, and the simulation results of steam reforming side of the reactor are compared with corresponding predictions for thermally coupled steam reformer and also conventional fixed‐bed steam reformer reactor operated at the same feed conditions. This reactor produces two types of syngas with different H₂/CO ratios. Results revealed that H₂/CO ratio at the output of steam and tri‐reforming sides reached to 1.1 and 9.2, respectively. In this configuration, steam reforming reaction is proceeded by excess generated heat from tri‐reforming reaction instead of huge fired‐furnace in conventional steam reformer. Elimination of a low performance fired‐furnace and replacing it with a high performance reactor causes a reduction in full consumption with production of a new type of synthesis gas. The reactor performance is analyzed on the basis of methane conversion and hydrogen yield in both sides and is investigated numerically for various inlet temperature and molar flow rate of tri‐reforming side. A mathematical heterogeneous model is used to simulate both sides of the reactor. The optimum operating parameters for tri‐reforming side in thermally coupled tri‐reformer and steam reformer reactor are methane feed rate and temperature equal to 9264.4 kmol h^?1 and 1100 K, respectively. By increasing the feed flow rate of tri‐reforming side from 28,120 to 140,600 kmol h^?1, methane conversion and H₂ yield at the output of steam reforming side enhanced about 63.4% and 55.2%, respectively. Also by increasing the inlet temperature of tri‐reforming side from 900 to 1300 K, CH₄ conversion and H₂ yield at the output of steam reforming side enhanced about 82.5% and 71.5%, respectively. The results showed that methane conversion at the output of steam and tri‐reforming sides reached to 26.5% and 94%, respectively with the feed temperature of 1100 K of tri‐reforming side. Copyright © 2013 John Wiley & Sons, Ltd.     

Mn-containing ZSM-5 type zeolite as a water-oxidizing catalyst: New findings and current controversies

Water-splitting for H₂ and O₂ production is a key reaction toward a clean energy future. However, the water-oxidation is one of the major limiting factors affecting the efficiency of this important reaction. Thus, the development of low-cost and efficient water-oxidizing catalysts is a key challenge in the artificial photosynthesis field. In this work, Mn-containing ZSM-5 type zeolite was synthesized using silicic acid, manganese(II) chloride tetrahydrate, potassium carbonate and tetrapropylammonium bromide (TPAB). Samples were characterized by different methods. The water-oxidizing activity of the catalysts were studied in the presence of cerium(IV) ammonium nitrate (Ce(IV)) and in the electrochemical water-oxidation condition. The effect of K⁺ ions on the structural properties and the catalytic performance of the compounds was also investigated. It was observed that after treating of manganosilicate with a Ce(IV) solution or applying a 2 V constant potential to the sample, in a convective–suspension–collision system, framework located Mn ions completely leaked. These results are important to reconsider the true catalysts in the different catalytic reactions in the presence of manganosilicates.     

Multidisciplinary optimization of a stiffened shell by genetic algorithm

Vibration analysis of simply supported rotating cross-ply laminated stiffened cylindrical shell is performed using an energy approach which includes variational and averaging method. The stiffeners include rings and stringers. The equations are obtained by Rayleigh-Ritz method and Sander’s relations. To validate the present method, the results are compared to the results available in other literatures. A good adoption is observed in different type of results including isotropic shells, rotating laminated shells, stiffened isotropic shells and stiffened laminated shells. Then, the optimization of parameters due to shell and stiffeners is conducted by genetic algorithm (GA) method under weight and frequency constraints. Stiffener shape, material properties and dimensions are also optimized.     

Amide-Based Surfactants from Methyl Glucoside as Potential Emulsifiers

A series of amide-linked surfactants from methyl glucoside was synthesized and investigated for their potential use as water-in-oil emulsifiers. The synthetic concept combined a nucleophilic substitution approach with a Staudinger coupling of the intermediate azide. Both straight and Guerbet-type branched fatty acids ranging from C₈ to C₁₆ were applied. All surfactants exhibited very high Krafft temperatures, which were related to the amide linkage and exclusively formed the hexagonal H₁-phase. The Guerbet C₁₆ surfactant enabled the formation of a stable water-in-oil gel at ambient temperature, which, however, required heating to form the corresponding fluid emulsion.     

Controlled radical copolymerization of vinyl acetate and dibutyl maleate by iodine transfer radical polymerization

Iodine transfer radical homo‐ and copolymerization of vinyl acetate (VAc) with dibutyl maleate (DBM) were carried out in the presence of ethyl iodoacetate (EtIAc) and 2,2′‐azobis(isobutyronitrile) (AIBN) as chain transfer agent and initiator, respectively, at 60 °C. Molecular weight and its distribution and (co)polymer structure (i.e. copolymer composition and chain end groups) were analysed using gel permeation chromatography and ¹H NMR spectroscopy, respectively. Homo‐ and copolymerization reactions proceed via a controlled characteristic with predetermined molecular weight and relatively narrow molecular weight distribution. The presence of DBM in the reaction mixture decreases the consumption rate of EtIAc as well as the polymerization rate. This is attributed to the effect of DBM on the transfer constant to the EtIAc and probably on the iodine exchange rate constant between the growing chains. The effect of the concentration of AIBN, EtIAc and overall monomers on the conversion, molecular weight and its distribution was studied. Simultaneously high conversion and molecular weight with a relatively narrow molecular weight distribution can be achieved only when equimolar and intermediate concentration of EtIAc and AIBN is used in the reaction mixture. End‐group analysis by ¹H NMR reveals that iodinated VAc end groups in the (co)polymer chains are unstable, resulting in aldehyde end groups. Thermogravimetric analysis shows that the thermal stability of the VAc‐based polymer increases on incorporating DBM units into the copolymer chains. © 2013 Society of Chemical Industry     

A simulation-optimization approach for open-shop scheduling problem with random process times

In this paper, an open-shop scheduling problem with stochastic process times is considered. The objective function is to minimize the weighted sum of earliness and tardiness costs. This type of objective function, in addition to the optimal schedule, puts forward the issue of finding optimal values of start times of jobs. In scheduling problems with stochastic process times, unlike the deterministic variants, it is not possible to determine the schedule before the random variables are realized. Whenever a machine becomes available (for example finishes processing some jobs) a job should be selected to be passed on it from the set of available jobs. This selection process is carried out in real-time. We have devised a simulation-optimization algorithm which calculates the distribution functions of the completion times of jobs via central limit theorem. These distribution functions are used for cost estimation in the real-time job selecting process. In other words, whenever some jobs are competing for a free machine, a pair wise cost competition is raised among them and the winner is passed on the free machine. Moreover, the distribution function of the completion time of each job is also used to adjust its start time. Finally, some test problems are generated and solved by our algorithm. The results demonstrate that our algorithm, even without adjusting the start times, outperforms the algorithm which acts randomly in the real-time job selecting process.     

Requirements-driven incremental adoption of variability management techniques and tools: an industrial experience report

In theory, software product line engineering has reached a mature state. In practice though, implementing a variability management approach remains a tough case-by-case challenge for any organization. To tame the complexity of this undertaking, it is inevitable to handle variability from multiple perspectives and to manage variability consistently across artifacts, tools, and workflows. Especially, a solid understanding and management of the requirements to be met by the products is an inevitable prerequisite. In this article, we share experiences from the ongoing incremental adoption of explicit variability management at TRW Automotive’s department for automotive slip control systems—located in Koblenz, Germany. On the technical side, the three key drivers of this adoption effort are (a) domain modeling and scoping, (b) handling of variability in requirements and (c) tighter integration of software engineering focus areas (e.g., domain modeling, requirements engineering, architectural modeling) to make use of variability-related data. In addition to implementation challenges with using and integrating concrete third-party tools, social and workflow-related issues are covered as well. The lessons learned are presented, discussed, and thoroughly compared with the state of the art in research.     

Novel anti‐bacterial acid dyes derived from naphthalimide: synthesis,characterisation and evaluation of their technical properties on nylon 6

As an attempt to combine the dyeing and functional finishing steps into one process, two novel anti‐bacterial monoazo acid dyes based on N‐ester‐1,8‐naphthalimide were synthesised. To do this, 4‐amino‐N‐ethyl glycinate‐1,8‐naphthalimide was prepared, diazotised and then coupled to thiosalicylic acid or salicylic acid to produce anti‐bacterial dyes. The synthesised dyes were purified and then fully characterised using Fourier Transform–infrared spectrometry, proton nuclear magnetic resonance spectroscopy and melting point analysis. Dispersion of the dyes was prepared in water and applied to nylon 6 fabrics. The novel dyes offered good build‐up properties on the substrate. The anti‐bacterial efficacy of the synthesised dyes was assessed, with the dyes showing activity against both Gram‐positive and Gram‐negative bacteria.