Subsurface plastic deformation in machining annealed red brass

The effect of cutting speed and tool geometry on the plastic deformation in the surface region of annealed red brass machined orthogonally under lubricated and unlubricated conditions is determined using the grid technique and metallography.The results show that the magnitude of the plastic deformation in the surface region and the depth of the work-hardened layer increase with a decrease in the cutting speed or the tool rake angle. Change in the tool wear land length produces a lesser change in the subsurface deformation than that observed to be due to a change in the other cutting parameters.The presence of the lubricant in the cutting region results in a considerable reduction in the subsurface damage.     

Heterogeneous Load Balancing using Predictive Load Summarization

Wireless Personal Communications - Enhanced throughput under efficient dynamic spectrum access is possible by secondary access based cognitive radio networking in TV white space (TVWS). The current...     

An Efficient Cross Layer Design of Stability Based Clustering Scheme Using Ant Colony Optimization in VANETs

Wireless Personal Communications - Road Accident is a significant concern in every county. According to WHO (World Health Organization) reports, 1.3 million people died in road traffic crashes, and...     

Correction to: Heterogeneous Load Balancing using Predictive Load Summarization

Wireless Personal Communications -     

Dopant Engineering for Spiro-OMeTAD Hole-Transporting Materials towards Efficient Perovskite Solar Cells

One of the most prominent hole-transporting material (HTM) for hybrid perovskite solar cells has been 2,2″,7,7″-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9′-spirobifluorene (spiro-OMeTAD), which is commonly doped with metal bis(trifluoromethylsulfonyl)imide (M(TFSI)_n) salts that contribute to generating the active radical cation HTM species. The underlying role of the metal cation, however, remains elusive. Here, the effect of metal cations (M = Li, Zn, Ca, Cu, and Sc) on doping spiro-OMeTAD is analyzed by a combination of techniques, including electron paramagnetic resonance spectroscopy and cyclic voltammetry, which is complemented by photovoltaic device and hole mobility analysis. As a result, the authors reveal the superiority of Zn(TFSI)₂ salts in device performances as compared to the others, including redox-active Cu(TFSI)₂. This analysis thereby unravels new design principles for dopant engineering in HTMs for hybrid perovskite photovoltaics.     

Shape optimization of shallow domes subjected to external pressure

Shallow domes subjected to external pressure are extensively used in missile structures. The critical failure mode for these domes is buckling due to external pressure. Different closed form solutions are available to evaluate buckling pressure of dome shapes like ellipsoid and torisphere. The torisiphere dome is the optimum dome shape among conventional domes. Shape optimization is carried out to find the optimal dome shape among shallow domes subjected to external pressure. Dome geometry is generalized by cubic bezier polynomials. For carrying out shape optimization, a low fidelity model is preferred which can predict the critical buckling pressure of a general dome shape. Towards this a unified model is proposed which meets the above requirement. Using this unified model, shape optimization of dome for minimization of mass is carried out subjected to buckling constraint. The study yielded a dome shape different from conventional dome shapes with a mass saving of 6% over torispherical dome while meeting the buckling constraint. The results of unified model are also validated with high fidelity Finite Element Analysis.

     

Interpenetrating photopolymers for intraocular lens application

Interpenetrating photopolymer network materials suitable for intraocular lens application are presented. A rapidly curable, transparent, hydrophobic material with appropriate optical and thermomechanical properties has been prepared from Benzyl acrylate and Benzyl methacrylate. To improve its biocompatibility and optimize surface—cell interactions, this material was modified with respect to its hydrophobicity. Materials which are more hydrophobic, and more hydrophilic, than the base resin were prepared by copolymerization with either a fluoroacrylate or a PEG acrylate respectively. All materials were characterized for their optical and thermomechanical properties. Their in‐vitro cytotoxicity and interaction with mouse fibroblast cells were also studied. It was shown that all materials of the study were biocompatible and more hydrophilic materials resisted cell attachment and may be more suitable for IOL application than their more hydrophobic counter parts of the study. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44496.     

An intelligent model to predict the life condition of crude oil pipelines using artificial neural networks

Neural Computing and Applications - Inefficient scheduling of a pipeline system may lead to severe degradation and substantial economic losses. Earlier studies mostly focussed on corrosion and...     

An Aqueous Gelcasting Process for Sintered Silicon Carbide Ceramics

An aqueous gelcasting process for the preparation of dense as well as porous-sintered SiC ceramics has been described in this paper. A commercial silicon carbide powder coated with phenolic resin was used in this investigation. For the purpose of comparison, a pure SiC powder was also studied. ς potential and viscosity studies revealed that the pure SiC powder requires an electro-steric stabilization, whereas the phenolic resin-coated powder requires an electrostatic stabilization in order to produce their corresponding aqueous slurries with high solids content. Thermogravimetry and differential thermal analysis techniques have been used to study the decomposition behavior of phenolic resin. Aqueous slurries containing 25–50 vol% SiC powder were gelcast and sintered at 2150°C for 1 h. The sinterability of gelcast SiC samples was found to be highly influenced by the SiO₂ formed on the surface of SiC during aqueous processing, as confirmed by the Fourier transform infrared spectroscopy study. The results obtained from various characterization techniques suggest that in order to make dense SiC parts with >3.13 g/mL bulk density (a theoretical density of 97.5%) by an aqueous gelcasting process, the starting phenolic resin (∼5%)-coated SiC powder should possess a median particle size of <11.0 μm, surface area of >3.2 m²/g, a compact (green) density of >1.67 g/mL, and a B content of >0.5%. Further, by using polyethylene granules and organic foaming agents, sintered SiC foam with a porosity of >80%, a compressive strength of >16 MPa and a coefficient of thermal expansion of 4.574 × 10⁻⁶/°C between 30° and 700°C can be prepared by an aqueous gelcasting process, followed by sintering at 2150°C for 1 h.     

Cloisite clay‐infused phenolic foam nanocomposites

A sonochemical technique was developed to infuse Cloisite clay nanoparticles into phenolic foam materials. Phenolic resin solution (Part A) was mixed with clay particles, and irradiated using a high intensity ultrasonic liquid processor. In the next step, the modified phenolic resin solution containing clay particles was mixed with Part B (containing phenol sulfonic acid, catalyst) through a high‐speed mechanical stirrer. The reaction mixture was then cast into rectangular molds to make nanophased foam panels. Test coupons were cut precisely from the panels to carry out thermal, morphological, and mechanical characterizations. The as‐prepared foam samples were characterized by scanning electron microscopy (SEM), X‐ray diffraction, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The SEM studies have shown that the particles are well dispersed over the entire volume of the matrix with minimal agglomeration. The foam cells structures are well‐ordered and uniform in size and shape. The TGA and DSC analyses show that the nanophased foams are thermally more stable than the corresponding neat system. Quasistatic compression tests have been carried out for both nanophased and neat foams systems. The test results show that there is a significant increase (approximately in the range of 150–180%) in the compressive strength and modulus of the nanophased foams over the neat system. This improvement in compressive properties has been noted repeatedly for multiple batches and with a minimum of three specimens tested from each batch. Details of the synthesis, thermal and mechanical characterization are presented in this paper. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 308‐314, 2007