Scale effects on buckling analysis of orthotropic nanoplates based on nonlocal two-variable refined plate theory

This article presents the buckling analysis of orthotropic nanoplates such as graphene using the two-variable refined plate theory and nonlocal small-scale effects. The two-variable refined plate theory takes account of transverse shear effects and parabolic distribution of the transverse shear strains through the thickness of the plate, hence it is unnecessary to use shear correction factors. Nonlocal governing equations of motion for the monolayer graphene are derived from the principle of virtual displacements. The closed-form solution for buckling load of a simply supported rectangular orthotropic nanoplate subjected to in-plane loading has been obtained by using the Navier’s method. Numerical results obtained by the present theory are compared with first-order shear deformation theory for various shear correction factors. It has been proven that the nondimensional buckling load of the orthotropic nanoplate is always smaller than that of the isotropic nanoplate. It is also shown that small-scale effects contribute significantly to the mechanical behavior of orthotropic graphene sheets and cannot be neglected. Further, buckling load decreases with the increase of the nonlocal scale parameter value. The effects of the mode number, compression ratio and aspect ratio on the buckling load of the orthotropic nanoplate are also captured and discussed in detail. The results presented in this work may provide useful guidance for design and development of orthotropic graphene based nanodevices that make use of the buckling properties of orthotropic nanoplates.     

Studies on the photochemical deposition (PCD) of II–VI compound semiconductor thin films of ZnS from aqueous solution

Zinc sulphide (ZnS) thin films were depositedon Indium oxide coaled glass substrates by Photo Chemical Deposition (PCD) with starting precursor of Zinc sulphate and sodium thiosulphate as a source material for Zn and S respectively. In addition the pH was varied (3 to 8) using sulphuric acid by adding up in the precursor. Later the ZnS thin films were annealed at 500°C and it was found that crystalline structure was improved. Zinc blende crystalline structure was observed on the thin films using X-ray diffractometer (XRD). The morphological behavior was observed using Scanning electron microscope (SEM) and it reveals that the size of the grain increases after annealing at 500°C. UV-spectrometer was used to analyze the aqueous solution optical behavior before and after deposition. The average thickness of thin film was estimated as ～1.02 micron measured by stylus profilometer method.     

Effect of glycerol and short sisal fibers on the viscoelastic behavior of wheat flour based thermoplastic

Wheat flour based thermoplastic having glycerol content (20%, 23%, 25%, 30% and 35% w/w) were fabricated using extrusion followed by compression molding. Dynamic mechanical analysis (DMA) has been done with reference to the amount of glycerol, sisal fiber loading, frequency and temperature. Two transitions peaks were observed for the, matrix, one at low temperature, due to the molecular dynamics associated to glycerol rich phase, and another at high temperature attributed to the molecular relaxation of starch rich phase. By changing the amount of glycerol, it has been observed that, at all temperature ranges, a plasticization effect which concerns mainly in the starch rich phase. Introduction of sisal fiber (up to 10% w/w) increases the storage modulus of the thermoplastic matrix. The peak height of damping curves (tan δ) was lowered as the fiber content. The activation energy was calculated from the maximum temperature (T_max) of damping curves.     

Assessment via the modified gompertz-model reveals new insights concerning the effects of ionic liquids on biohydrogen production

Lignocellulosic biofuel, in particular hydrogen gas production is governed by successful feedstock pretreatment, hydrolysis and fermentation. In these days, remarkable attention is paid to the use of ionic liquids to make the fermentable regions of lignocellulose biomass more accessible to the biocatalysts. Although these compounds have great potential for this purpose, their presence during the consecutive fermentation stage may pose a threat on process stability due to certain toxic effects. This, however, has not been specifically elaborated for dark fermentative biohydrogen generation. Hence, in this work, two common imidazolium-type ionic liquids (1-butyl-3-methylimidazolium acetate, ([bmim][Ac]) and 1-butyl-3-methylimidazolium chloride, ([bmim][Cl])) were employed in mixed culture biohydrogen fermentation to investigate the possible impacts related to their presence and concentrations. The batch assays were evaluated comparatively via the modified Gompertz-model based on the important parameters characterizing the process, namely the biohydrogen production potential, maximum biohydrogen production rate and lag-phase time.     

Development of an integrated model for process planning and parameter selection for machining processes

The concept of ‘do it right the first time’ in the machining industry not only expects the best quality products but also at the best possible cost. The cost of machining depends on intelligent process planning and selection of machining parameters such as speed, feed, and depth of cut. The problem of machining parameter selection has received great attention by researchers and many techniques have been developed. A review of these techniques reveals that the selection of the machine and cutting tool is done before the process of cutting parameter selection and process sequencing, and often the selection is based on experience. The current research is an attempt to develop an integrated model (ExIMPro: Expert system based Integrated model for Machining Processes) which finds the sequence of operations with set of machines, tools, and other process parameters to minimise the cost of machining for a cylindrical part. This system consists of existing expert system Machining Parameter SELection (MPSEL) for machine and tool selection and a Microsoft Excel® and Visual Basic® based parameter selection model. The present model focuses on turning and cylindrical grinding operations but other processes can be incorporated with little modification to the software.     

High performance HTLNR/epoxy blend—Phase morphology and thermo-mechanical properties

An attempt was made to toughen diglycidyl ether of bisphenol A (DGEBA) type epoxy resin with liquid natural rubber possessing hydroxyl functionality (HTLNR). Epon 250 epoxy monomer is cured using nadic methyl anhydride as hardener in presence of N, N dimethyl benzyl amine as accelerator. HTLNR of different concentrations up to 20 wt % is used as modifier for epoxy resin. The addition HTLNR to an anhydride hardener/epoxy monomer mixture has given rise to the formation of phase-separated structure, consisting of small spherical liquid natural rubber particles bonded to the surrounding epoxy matrix. The particle size increased with increase in rubber content. The viscoelastic properties of the blends were analyzed using dynamic mechanical thermal analysis. The T_g corresponding to epoxy rich phase was evident from the dynamic mechanical spectrum, while the T_g of the rubber phase was overlapped by the β relaxation of epoxy phase. Glass transition of the epoxy phase decreased linearly as a function of the amount of rubber. The mechanical properties such as impact and fracture toughness were also carefully examined. The impact and fracture toughness increase with HTLNR content. A threefold increase in impact strength was observed with 15 wt % HTLNR/epoxy blend. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Robust Exponential Stability Criteria for T–S Fuzzy Stochastic Delayed Neural Networks of Neutral Type

This paper is concerned with the problem of robust exponential stability for T–S fuzzy stochastic neural networks of neutral type. Based on the Lyapunov–Krasovskii functional and stochastic analysis approach, new delay-dependent stability criteria are established in terms of linear matrix inequalities (LMIs) which can be checked easily by the LMI Control Toolbox in MATLAB. Finally, numerical examples are given to illustrate the feasibility and effectiveness of the proposed method.     

Extending P2PMesh: topology‐aware schemes for efficient peer‐to‐peer data sharing in wireless mesh networks

Wireless mesh networks (WMNs) have emerged as a promising technology that provides low‐cost broadband access to the Internet for fixed and mobile wireless end users. An orthogonal evolution in computer networking has been the rise of peer‐to‐peer (P2P) applications such as P2P data sharing. It is of interest to enable effective P2P data sharing in this type of networks. Conventional P2P data sharing systems are not cognizant of the underlying network topology and therefore suffer from inefficiency. We argue for dual‐layer mesh network architecture with support from wireless mesh routers for P2P applications. The main contribution of this paper is P2PMesh: a topology‐aware system that provides combined architecture and efficient schemes for enabling efficient P2P data sharing in WMNs. The P2PMesh architecture utilizes three schemes: (i) an efficient content lookup that mitigates traffic load imbalance at mesh routers; (ii) an efficient establishment of download paths; and (iii) a data transfer protocol for multi‐hop wireless networks with limited capacity. We note here that the path establishment and data transfer schemes are specific to P2P traffic and that other traffic would use routes determined by the default routing protocol in the WMN. Simulation results suggest that P2PMesh has the potential to improve the performance of P2P applications in a wireless multi‐hop setting; specifically, we focused on data sharing, but other P2P applications can also be supported by this approach. Copyright © 2011 John Wiley & Sons, Ltd.     

Influence of different types of water on strength, porosity and hydric parameters of metakaolin admixtured cement

The present research deals with strength, porosity and hydric behavior of metakaolin cement admixtured with different types of water. The hydration of ordinary Portland cement in the presence of 0%, 10%, 20% and 30% metakaolin treated with distilled, ground and sea water with the water to cement ratio of 0.4 was studied. The experimental results on setting time, strength, porosity and hydric parameters are reported. The results show that, metakaolin percentage increases in strength with a decrease in porosity. The observed results are discussed with SEM micrographs. Further, sea water accelerates the cement hydration at the early stages but retards it in the latter stages of hydration.     

The impact of organizational context on innovation adoption incommercial banks

This study examines the linkages between nonstructured factors in an organization's context and dimensions of innovation adoption in organizations. Elements of an organization's context included in this study are size, geographic scope, and product scope; dimensions of innovation are magnitude and speed of adoption and product and process types of innovation. The relationships among these variables are examined by a sampling of empirical data culled from 101 commercial banks in four states: New York; New Jersey; Connecticut; and Massachusetts. We found that: (1) organization size and geographic scope have a stronger association with magnitude than the speed of adoption, while product scope is more strongly linked to the speed of adoption; (2) geographic and product scope influence the propensity to adopt product and process innovations differently; and (3) the pattern of innovation adoption differs among various types of banks