Optimization in CNC end milling of UNS C34000 medimum leaded brass with multiple surface roughnesses characteristics

The present study highlights a multi-objective optimization problem by applying utility concept coupled with Taguchi method through a case study in CNC end milling of UNS C34000 medium leaded brass. The study aimed at evaluating the best process environment which could simultaneously satisfy multiple requirements of surface quality. In view of the fact, the traditional Taguchi method cannot solve a multi-objective optimization problem; to overcome this limitation, utility theory has been coupled with Taguchi method. Depending on Taguchi’s Lower-the-Better (LB) response criteria; individual surface quality characteristics has been transformed into corresponding utility values. Individual utility values have been aggregated finally to compute overall utility degree which serves as representative objective function for optimizing using Taguchi method. Utility theory has been adopted to convert a multi-response optimization problem into a single response optimization problem; in which overall utility degree serves as the representative single objective function for optimization. The study of combined utility theory and Taguchi method for predicting optimal setting. Based on Taguchi’s Signal-to-Noise ratio (S/N), analysis has been made on the overall utility degree and optimal process environment has been selected finally which corresponds to highest S/N Ratio. Optimal result has been verified through confirmatory test. The case study indicates application feasibility of the aforesaid methodology proposed for multiresponse optimization and off-line control of multiple surface quality characteristics in CNC end milling.     

Fracture Resistance of a Transparent Magnesium Aluminate Spinel

The fracture resistance of a fully dense, transparent, polycrystalline magnesium aluminate spinel was measured from room temperature to 1400°C using the chevron-notched beam and the straight-notched beam macroflaw techniques, as well as the indentation-induced, controlled-microflaw test method, all in three-point bending. Flexural strengths were also measured for the same range of temperatures to compare with the fracture toughness measurements. From the load vs load-line displacement ( P-u ) curves of the chevronnotched test specimens, the crack growth resistance curves ( R -curves) and the total work-of-fracture were determined. It was observed that polycrystalline MgAl₂O₄ exhibits rising R -curve behavior which increases with increasing test temperature. The R -curve increases are attributed to the geometric constraints due to grain bridging and grain wedging phenomena as well as secondary grain boundary microcracking processes, all of which occurred in the wake region behind the advancing crack. The work-of-fracture and the R -curves increased rapidly above 800°C coincident with the onset of increased secondary grain boundary microcracking.     

Detecting Byzantine attack in cognitive radio networks using machine learning

Wireless Networks - One primary function in a cognitive radio network (CRN) is spectrum sensing. In an infrastructure-based CRN, instead of individual nodes independently sensing the presence of...     

Finger contour profile based hand biometric recognition

Multimedia Tools and Applications - This paper presents a contactless hand biometric system at unrestricted hand pose environment. A new preprocessing technique is proposed for defining the finger...     

A Facile Synthesis of a Palladium-Doped Polyaniline-Modified Carbon Nanotube Composites for Supercapacitors

Supercapacitors have evolved as the premier choice of the era for storing huge amounts of charge in the field of energy storage devices, but it is still necessary to enhance their performance to meet the increasing requirements of future systems. This could be achieved either through advancing the interfaces of the material at the nanoscale or by using novel material compositions. We report a high-performance material composition prepared by combining a transition metal (palladium)-doped conductive polymer with multiwalled carbon nanotubes (MWCNTs). MWCNTs/palladium-doped polyaniline (MWCNTs/Pd/PANI) composites and multiwalled carbon nanotube/polyaniline (MWCNTs/PANI) composites (for comparison) were prepared via in situ oxidative polymerization of aniline monomer. The reported composites were characterized by Fourier-transform infrared (FTIR), x-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM) studies. FESEM and TEM studies indicated the narrow size distribution of the π-conjugated polymer-protected palladium nanoparticles on the surface of the carbon nanotubes. All the electrochemical characterizations were executed using a three-electrode system in 1 M H₂SO₄ electrolyte. Cyclic voltammetry (CV) analysis was performed to observe the capacitive performance and redox behavior of the composites. The ion transfer behavior and cyclic stability of the composites were investigated by electrochemical impedance spectroscopy (EIS) analysis and cyclic charge–discharge (CCD) testing, respectively. The MWCNTs/Pd/PANI composite was found to exhibit an especially high specific capacitance value of 920 F/g at scan rate of 2 mV/s.     

Chilika Lagoon: Restoring ecological balance and livelihoods through re-salinization

This paper reviews the past and present conditions and management of Chilika Lagoon, the largest lagoon on India's eastern coast. Spatial and temporal salinity gradients, because of freshwater river inflow and seasonal seawater influx, have created unique characteristics of an estuarine ecosystem, and exercised a continuous, selective influence on the biota. Unfortunately, its biodiversity and the livelihoods that depend on it were being lost at a fast rate because of a blockage of the lagoon's mouth by silt coming from upstream catchments, as well as oceanic long‐shore transport. Projects to restore the dynamic characteristics of the lagoon included dredging a new mouth to the ocean, as well as prevention of soil erosion in upstream areas. Management efforts resulted in a dramatic revival of this ecosystem, and contributed to a sharp rise in the incomes of fisherfolk. The institutional aspects of implementing such large‐scale policy changes also are discussed, and the remaining issues and lessons learned are presented.     

Synergistic Effect of Halloysite Nanotubes and MA-g-PE on Thermo-Mechanical Properties of Polycarbonate-Cyclic Olefin Copolymer Based Nanocomposite

This article explores the synergistic effect of halloysite nanotubes along with maleic anhydride grafted polyethylene on the physical, mechanical, and thermo-mechanical properties of polycarbonate/cyclic olefin copolymer polymer blend system. Halloysite nanotubes filled polycarbonate/cyclic olefin copolymer blend nanocomposites were prepared in the presence and absence of polymeric compatibilizer by melt blending. Besides the constructive outcome of nanotubular fillers, the maleic anhydride grafted polyethylene played a complementary role in improving the properties of the nanocomposites. Structural changes of blend matrix, nanofiller distributions, nanofiller-polymer matrix interaction, nucleating effect, storage modulus, and thermal stability were widely investigated with various sophisticated instruments.     

An Efficient Synthesis of a Hydroxyethylamine (HEA) Isostere and Its α-Aminophosphonate and Phosphoramidate Derivatives as Potential Anti-HIV Agents

HIV protease is a promising drug target for AIDS therapy, and several potent HIV‐1 protease inhibitors have been reported to date. Although existing inhibitors exhibit high selectivity, they have also been associated with severe side effects and the possible emergence of therapeutic resistance. As HIV protease cleaves the peptide bond via a tetrahedral intermediate, various transition‐state models such as hydroxyethylamine (HEA) have been designed. We therefore pursued an efficient synthesis of an HEA isostere; this was performed with a novel one‐pot reduction–transimination–reduction reaction sequence as a key step. α‐Aminophosphonate and phosphoramidate derivatives of the HEA isostere were designed and synthesized, and all of the synthesized derivatives were assayed for their anti‐HIV activities against wild‐type and mutant HIV strains. Phosphoramidate derivative 15 a was found to be the most active of all synthesized compounds against the III_B and RES056 strains. As phosphonates are known to exhibit physiological stability, good cell permeability, and other promising pharmacokinetic characteristics, our newly synthesized compounds have the potential as alternatives to existing therapeutics and diagnostics.