Combined analytical and numerical approach for auxetic FG-CNTRC plate subjected to a sudden load

In the current work, the dynamic behavior of functionally graded carbon nanotube-reinforced composite (FG-CNTRC) plate with negative Poisson’s ratio (NPR) is investigated by combining higher-order shear deformation theory and large deflection theory. First, explicit solutions are proposed to predict the effective Poisson’s ratio (EPR) of the laminates. Taking carbon nanotube-reinforced composite (CNTRC) as an example, the maximum NPR is obtained for \(\left( { \pm \theta } \right)_{{3{\text{T}}}}\) laminate as well. Results show that the EPR (\(v_{13}^{\text{e}}\),\(v_{23}^{\text{e}}\)) can range from a positive value of 0.311 to a negative value of 0.63. For the dynamic response problem, the asymptotic solutions with a two-step perturbation approach are derived for FG-CNTRC plates to capture the relationship between the center deflection and time. Several key factors such as functionally graded distribution, variations in the elastic foundation, and thermal stress produced by changing the temperature field are considered in the subsequent analysis. Numerical simulations are carried out to examine the corresponding dynamic behavior of FG-CNTRC plates when these factors are taken into account.

     

New corrosion inhibitors based on fatty materials—II. Epoxidized fatty materials modified with aromatic amines

Eight compounds prepared by modification of epoxidized linseed oil and oleic acid with aniline, p-chloro-aniline, p-toluidine and p-anizidine, were tested as corrosion inhibitors. The test coupons were mild steel and the environment consisted of 0.05N HCl at 70°C or mixed vapours of gasoline and HCl. In HCl, the percentage inhibition ranged from 26.0 to 59.5% for linseed oil and from 88.0 to 94.5% for oleic acid derivatives. In the gas phase, the ranges were from 70.3 to 85.98 and from 62.5 to 74.0%, respectively. The values obtained for two commercial inhibitors tested under the same conditions were 34.5 and 91.7% in HCl and 57.0 and 64.0% in the mixed vapours. The results conformed with a simple Langmuir model and with predictions based on NMR measurements, basicity values (pK_a) and Hammett constants. A ranking of the compounds according to percentage inhibition agreed with the order of increasing electron density on the nitrogen atom in these compounds.     

Interactions betweenKalmia and black spruce: Isolation and identification of allelopathic compounds

Aqueous extracts of fresh leaves and organic soil of northern sheep laurel (Kalmia angustifolia var.angustifolia) were found to be inhibitory to the growth of black spruce (Picea mariana) germinants. Primary root growth of black spruce was more affected by the extracts than was shoot growth. The growth inhibition caused by the leaf extract was most pronounced under acidic conditions (pH 3–4). The aqueous extract ofKalmia leaves contained ferulic, vanillic, syringic, gentisic,m-coumaric,p-coumaric,o-hydroxyphenylacetic, andp-hydroxybenzoic acids as well as some other unknown compounds. These compounds were isolated from the aqueous extract ofKalmia leaves by ethyl acetate extraction and identified using thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC). Bioassay indicated that the overall toxicity of the phenolic compounds to black spruce appeared to increase in the order ofo-hydroxyphenylacetic,p-hydroxybenzoic, vanillic,p-coumaric, gentisic, syringic, ferulic, andm-coumaric acids.     

Silver recovery from radiographic film processing effluents by hydrogen peroxide: Modeling and optimization using response surface methodology

The recovery of silver from X-ray film processing effluents by precipitation using hydrogen peroxide as the precipitating agent was studied. Response surface methodology (RSM) and central composite design (CCD) were applied to achieve optimum conditions. Linear, square and interactions effects between parameters to study of a second order polynomial equation were obtained. Optimum condition included the volume of H₂O₂ 0.8 ml/min, pH=5.5, ethylene glycol 9 ml in the experimental condition. In these conditions silver recovery percentage was predicted as 92.8%. The experiment was conducted in triplicate under optimized conditions. Silver recovery percentage and average of precipitate were obtained as 91.5% and 423.19mg, respectively, which were close to the predicted amount achieved by the model.     

Joining of passive dissimilar metals—Ti,SS and AL: An emerging application of electrodeposition

The joining of dissimilar metals is an emerging area in electroplating which is yet to receive popularity. This technique finds wide application in the space and nuclear industries, h electrochemical joining, electrodeposition is used to build up the joint. In this work, the authors have joined difficult-to-plate metals such as titanium, stainless steel and aluminum. The pre-plating and plating sequences, operating conditions and the joint design are found to be the deciding factors in deciding the strength of the joints.     

Characterization and Mechanical Properties of Calcium Silicate/Citric Acid–Based Polymer Composite Materials

Optimal implants for bone tissue engineering require sufficient mechanical strength as well as apt bioactivity and biodegradability. Calcium silicate (CaSiO₃ ‐ CS) ceramics have been studied for tissue engineering and implantation for their good bioactivity properties. Elastomer poly (1.8‐octanediol citrate) (POC), one of the most biocompatible polymer, is used for biomedical application. The objective of this study is to fabricate a novel composite of calcium silicate with different ratios of POC to enhance the mechanical properties. The results showed that the compressive and the bending strengths of calcium silicate/POC biocomposite were improved remarkably at 40 wt% POC.     

Restoration Probability Modelling for Active Restoration-Based Optical Networks with Correlation Among Backup Routes

Active restoration (AR) is a novel lightpath restoration scheme proposed recently to guarantee a certain degree of survivability in wavelength-division multiplexing (WDM) optical networks with a reasonable trade-off between capacity requirement and restoration time. In this paper, we conduct a comprehensive performance analysis for AR-based optical networks. In particular, we propose a novel analytical framework for modeling the restoration probability of a connection (the probability that the connection can be successfully restored in case of a failure) when the possible correlation among its multiple backup routes is incorporated. Although theoretically, we need to consider all the possible correlations between as many as Q) pairs of backup routes to analyze the restoration probability in a network with N nodes, and this high computation complexity may obscure the practicality of an approach, considering all the possible correlations among backup routes, our analysis in this paper indicates that by considering at most the possible correlations among any three successive backup routes of a connection, we can achieve a very good approximation to the simulated restoration probability of the connection, as verified by extensive simulation results upon two typical network topologies under various workloads. We find that the proposed framework can deeply investigate into the inherent relationship among restoration probability, wavelength channel utilization ratio, number of wavelengths per fiber, routes hop length, and wavelength conversion capability. As a result, the framework significantly contributes to the related areas by providing network designers with a quantitative tool to evaluate the restoration probability and, thus, the survivability of AR-based optical networks.     

A Reliable Link-Layer Protocol for Robust and Scalable Intervehicle Communications

Current link-layer protocols for safety-related intervehicle communication (IVC) networks suffer from significant scalability and security challenges. Carrier sense multiple-access approaches produce excessive transmission collisions at high vehicle densities and are vulnerable to a variety of denial of service (DoS) attacks. Explicit time slot allocation approaches tend to be limited by the need for a fixed infrastructure, a high number of control messages, or poor bandwidth utilization, particularly in low-density traffic. This paper presents a novel adaptation of the explicit time slot allocation protocols for IVC networks. The protocol adaptive space-division multiplexing (ASDM) requires no control messages, provides protection against a range of DoS attacks, significantly improves bandwidth utilization, and automatically adjusts the time slot allocation in response to changes in vehicle densities. This paper demonstrates the need for and the effectiveness of this new protocol. The exposures of the current proposals to attacks on availability and integrity, as well as the improvements effected by ASDM, are analytically evaluated. Furthermore, through simulation studies, ASDM's ability to provide message delivery guarantees is contrasted with the inability of the current IVC proposals to do the same