Synthesis of poly(methyl methacrylate)/silica nanocomposite through emulsion polymerization using dimethylaminoethyl methacrylate

Polymer/Silica nanocomposite latex particles were prepared by emulsion polymerization of methyl methacrylate (MMA) with dimethylaminoethyl methacrylate (DM). The reaction was performed using a nonionic surfactant and in the presence of silica nanoparticles as the seed. The polymer‐coated silica nanoparticles with polymer content and number average particle sizes ranged from 32 to 93 wt % and 114–310 nm, respectively, were obtained depending on reaction conditions. Influences of some synthetic conditions such as MMA, DM, surfactant concentration, and the nature of initiator on the coating of the silica nanoparticles were studied. Electrostatic attraction between anionic surface of silica beads and cationic amino groups of DM is the main driving force for the formation of the nanocomposites. It was demonstrated that the ratio of DM/MMA is important factor in stability of the system. The particle size, polymer content, efficiency of the coating reaction, and morphology of resulted nanocomposite particles showed a dependence on the amount of the surfactant. Zeta potential measurements confirmed that the DM was located at the surface of the nanocomposites particles. Thermogravimeteric analysis indicated a relationship between the composition of polymer shell and polymer content of the nanocomposites. The nanocomposites were also characterized by FTIR and differential scanning calorimetry techniques. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Dynamic response of a beam carrying a lumped mass along its span

In this paper, we study the periodic solutions for the free vibration of a conservative oscillator with fifth-order nonlinearity using two new methods, the energy balance method and the variational approach. We compare the results obtained with those yielded by the traditional harmonic balance method and equivalent linearization–nonlinearization method. The periodic solutions are then verified using the Runge–Kutta approach.     

Reverse iodine transfer polymerization of vinyl acetate and vinyl benzoate: synthesis and characterization of homo‐ and copolymers

Homo‐ and copolymers of vinyl esters including vinyl acetate (VAc) and vinyl benzoate (VBz) were synthesized via the reverse iodine transfer radical polymerization technique. Polymerization was carried out in the presence of iodine as the in situ generator of the transfer agent and 2,2′‐azobis(isobutyronitrile) as the initiator at 70 °C. Reverse iodine transfer radical homopolymerization of VAc and VBz led to conversions of 76 and 57%, number‐average molecular weights of 8266 and 9814 g mol^?1 and molecular weight distributions of 1.58 and 1.49, respectively. The microstructure of the synthesized polymers was investigated in detail using gel permeation chromatography, ¹H NMR, ¹³C NMR and distortionless enhancement of polarization transfer (135° decoupler pulse) techniques. Relatively narrow molecular weight distribution and controlled and predictable trend of molecular weight versus conversion were observed for the synthesized polymers, showing that reverse iodine transfer radical homo‐ and copolymerization of VAc and VBz proceeded with controlled characteristics. Results of molecular weight and its distribution along with the ¹H NMR spectra recorded for homo‐ and copolymers indicated that side reactions can occur during the course of polymerization with a significant contribution when VAc, even in a small amount, was present in the reaction mixture. This can result in polymer chains with aldehyde dead end and broadening of the molecular weight distribution. © 2015 Society of Chemical Industry     

A PSO-based optimum consumer incentive policy for WEEE incorporating reliability of components

The world is going digital, human infatuation with gadgets is increasing and a very short product lifecycle of these products has resulted in a horrendous threat to the environment. Waste electrical and electronic equipment (WEEE) reverse logistic management has been a key area for researchers to innovate and produce insights that could sustain businesses without compromising the environment. In this paper, we aim to understand the consumer return behaviour of end of life goods at different incentive levels and make an attempt to incorporate the latest research practices. A novel attempt is made in this paper, where we have for the first time applied product and component reliability in determining the incentives given to the consumer so that the efforts of WEEE recycling and disposal could be conducted in an economically sustainable manner to promote ecological sustainability, thereby envisaging upon the fact that there is a hidden synergy between the trade and environment, and only innovative managerial approaches that are thoroughly pragmatic, could exploit them. The optimisation model has been solved using particle swarm optimisation (PSO) and the insights produce highlight upon the feasibility of such a model.     

Big Data Based Self-Optimization Networking in Next Generation Mobile Networks

Using self-optimization techniques is the only viable solution for increasing the efficiency in next generation mobile networks. The goal of proposing a self-optimization model is to maximize the network efficiency and increase the quality of services provided to microcell and femto-cell users, considering the limited resources in radio access networks. To increase the model efficiency, we applied the big data technique for analyzing data and increasing the accuracy of the decision-making process. Based on the meaningful extracted information, the SON decision maker will be able to adjust network parameters and resource allocation factors in a more intelligent manner. The experimental results show that despite the tremendous volume of the analyzed data—which is hundreds of times bigger than usual methods—it is possible to improve the KPIs, such as throughput, up to 30% by optimal resource allocation and reducing the signaling load. Also, the presence of feature extraction and parameter selection modules will reduce the response time of the self-optimization model up to 25% when the number of parameters is too high. Moreover, numerical results indicate the superiority of using support vector machine learning algorithm. It improves the accuracy level of decision making based on the rule-based expert system. Finally, uplink quality improvement and 15% increment of the coverage area under satisfied SINR conditions can be considered as outcome of the proposed scheme.     

Numerical solution of stokes flow in a circular cavity using mesh-free local RBF-DQ

This work reports the results of a numerical investigation of Stokes flow problem in a circular cavity as an irregular geometry using mesh-free local radial basis function-based differential quadrature (RBF-DQ) method. This method is the combination of differential quadrature approximation of derivatives and function approximation of Radial Basis Function. As a result, the method can be used to directly approximate the derivatives of dependent variables on a scattered set of knots. In this study knots were distributed irregularly in the solution domain using the Halton sequences. The method is applied on a two-dimensional geometry. The obtained results from the numerical simulations are compared with those gained by previous works. Outcomes prove that the current technique is in very good agreement with previous investigations and this fact that RBF-DQ method is an accurate and flexible method in solution of partial differential equations (PDEs).     

Approximate analysis of two-mass–spring systems and buckling of a column

Max–Min Approach (MMA) is applied to obtain an approximate solution of three practical cases in terms of a nonlinear oscillation system. After finding maximal and minimal solution thresholds of a nonlinear problem, an approximate solution of the nonlinear equation can be easily achieved using He Chengtian’s interpolation. Numerical results indicate the effectiveness of the proposed method both in respect of the whole range of involved parameters as well as the excellent agreement with the approximate frequencies and periodic solutions with the exact ones. It is predicted that MMA can be found widely applicable in engineering.     

Ground (Weibull-Distributed) Clutter Suppression Based on Independent Component Analysis for Detection of Swerling Target Models

Journal of Communications Technology and Electronics - The present study considers detection of the weak Swerling targets which exist in the clutter Doppler cell of the Weibull-distributed...     

Surface Properties of an Alcohol Alkoxylate in the Presence of a Cationic Surfactant

Alcohol alkoxylate was prepared via propoxylation of an industrial alcohol ethoxylate. The chemical structure of the prepared compound was confirmed using FT-IR and the physical properties were evaluated by the usual methods according to ASTM. The surface properties of the aqueous solution of alcohol alkoxylate were determined with or without addition of a cationic surfactant in comparison to the corresponding alcohol ethoxylate. The measured parameters were surface tension, CMC, maximum surface excess, minimum surface area and the interaction parameter (β). These data indicate that surface properties changed due to the attractive complex formation in the mixed system.