Multi-objective optimization of process parameters in Electro-Discharge Diamond Face Grinding based on ANN-NSGA-II hybrid technique

The effective study of hybrid machining processes (HMPs), in terms of modeling and optimization has always been a challenge to the researchers. The combined approach of Artificial Neural Network (ANN) and Non-Dominated Sorting Genetic Algorithm-II (NSGA-II) has attracted attention of researchers for modeling and optimization of the complex machining processes. In this paper, a hybrid machining process of Electrical Discharge Face Grinding (EDFG) and Diamond Face Grinding (DFG) named as Electrical Discharge Diamond face Grinding (EDDFG) have been studied using a hybrid methodology of ANN-NSGA-II. In this study, ANN has been used for modeling while NSGA-II is used to optimize the control parameters of the EDDFG process. For observations of input-output relations, the experiments were conducted on a self developed face grinding setup, which is attached with the ram of EDM machine. During experimentation, the wheel speed, pulse current, pulse on-time and duty factor are taken as input parameters while output parameters are material removal rate (MRR) and average surface roughness (R_a). The results have shown that the developed ANN model is capable to predict the output responses within the acceptable limit for a given set of input parameters. It has also been found that hybrid approach of ANN-NSGA-II gives a set of optimal solutions for getting appropriate value of outputs with multiple objectives.     

Bulk scale production of carbon nanofibers in an economical way

An economical route for the scalable production of carbon nanofibers (CNFs) on a sodium chloride support has been developed. CNFs have been synthesized by chemical vapor deposition (CVD) method by using metal formate as catalyst precursors at 680°C. Products were characterized by SEM, TEM, Raman spectroscopy and XRD method. By thermal analysis, the purity of the as grown products and purified products were determined. This method avoids calcination and reduction process which was employed in commercial catalysts such as metal oxide or nitrate. The problems such as detrimental effect, environmental and even cost have been overcome by using sodium chloride as support. The yield of CNFs up to 7800 wt.% relative to the nickel catalyst has been achieved in the growth time of 15 min. The advantage of this synthesis technique is the simplicity and use of easily available low cost precursors.     

Influence of process variables and formulation composition on sphericity and diameter of Ca-alginate-chitosan liquid core capsule prepared by extrusion dripping method

ABSTRACT

The influence of process variables and formulation composition on the sphericity and diameter of the alginate capsules which contained dual cations (Ca-and-chitosan) are characterized in this study. Capsule sphericty was not influenced by needle diameter but instead, capsule diameter increased proportionally with the needle diameter. The combined effects of the liquid core solution and alginate solution on the sphericity of the capsules are tabulated. Spherical capsules can be produced when the following criteria were fulfilled: stirring speed is in the range of 240–300 rpm; calcium chloride concentration is >5 g/L; viscosity of liquid core solution is >203 mPa.s; as well as viscosity of alginate solution is in between 47 and 386 mPa.s. The capsule diameter was predicted using a modified Tate’s law equation and an error analysis was conducted to evaluate the equation. The predicted diameter was well correlated with the experimental data with an average absolute deviation <3.6%.     

Novel (phenylethynyl)pyrene-LNA constructs for fluorescence SNP sensing in polymorphic nucleic acid targets

We describe fluorescent oligonucleotide probes labeled with novel (phenylethynyl)pyrene dyes attached to locked nucleic acids. Furthermore, we prove the utility of these probes for the effective detection of single-nucleotide polymorphisms in natural nucleic acids. High-affinity hybridization of the probes and excellent fluorescence responses to single-base mismatches in DNA/RNA targets are demonstrated in model dual-probe and doubly labeled probe formats. This stimulated us to develop two diagnostic systems for the homogeneous detection of a drug-resistance-causing mutation in HIV-1 protease cDNA and RNA gene fragments. Target sequences were obtained by analysis of 200 clinical samples from patients currently receiving anti-HIV/AIDS combination therapy at the Russian Federal AIDS Center. Using these fluorescent oligonucleotides, we were able to detect the target mutation despite all the challenges of the natural targets, that is, the presence of additional mutations, neighboring sequence variation, and low target concentration, which typically reduce binding and effectiveness of sensing by fluorescent oligonucleotides.     

Stacking dependent electronic structure and transport in bilayer graphene nanoribbons

The stacking-dependent electronic structure and transport properties of bilayer graphene nanoribbons suspended between gold electrodes are investigated using density functional theory coupled with non-equilibrium Green’s functional method. We find substantially enhanced electron transmission as well as tunneling currents in the AA stacking of bilayer nanoribbons compared to either single-layer or AB stacked bilayer nanoribbons. Interlayer separation between the nanoribbons appears to have a profound impact on the conducting features of the bilayer nanoribbons, which is found to be closely related to the topology and overlap between the edge-localized π orbitals.     

Application of non-dominated sorting genetic algorithm for multi-objective optimization of electrical discharge diamond face grinding process

Hybrid machining processes (HMPs), having potential for machining of difficult to machine materials but the complexity and high manufacturing cost, always need to optimize the process parameters. Our objective was to optimize the process parameters of electrical discharge diamond face grinding (EDDFG), considering the simultaneous effect of wheel speed, pulse current, pulse on-time and duty factor on material removal rate (MRR) and average surface roughness (Ra). The experiments were performed on a high speed steel (HSS) workpiece at a self developed face grinding setup on an EDM machine. All the experimental results were used to develop the mathematical model using response surface methodology (RSM). The developed model was used to generate the initial population for a genetic algorithm (GA) during optimization, non-dominated sorting genetic algorithm (NSGA-II) was used to optimize the process parameters of EDDFG process. Finally, optimal solutions obtained from pareto front are presented and compared with experimental data.     

Effect of nano-alumina concentration on the properties of poly(vinyl chloride)/thermoplastic polyester elastomer blend system

Poly(vinyl chloride) (PVC)/thermoplastic polyester elastomer (Hytrel) blend system prepared in 50/50 composition was found to have the highest possible percentage elongation-at-break. This is due to better molecular compatibility between the two; however, they had lower strength and modulus values. In order to improve the strength and modulus property, alumina nano-particles were added as a reinforcing agent in concentrations as 1, 3, 5, and 7 phr in the blend system. The prepared nanocomposites were characterized for mechanical, thermal, rheological, morphological, and electrical properties. The 5-phr nano-alumina loaded PVC/Hytrel blend had optimal improvement in its strength values, but above that concentration nano-alumina started forming aggregates as was apparent from scanning electron microscopy (SEM) analysis. SEM images showed uniform distribution of nano-alumina in both PVC and Hytrel phases of the blend. Tensile strength and modulus were found to have increased by about 20 and 97 %, respectively, whereas elongation at maximum load decreased by 50 %, indicating the effect of nano-alumina as a reinforcing agent in the PVC/Hytrel system. The glass transition temperature, onset degradation temperature, viscosity, surface resistivity and volume resistivity increased, whereas degradation weight loss (%) decreased with increase in nano-alumina concentration in PVC/Hytrel blend system. No chemical interaction happened between PVC, Hytrel or alumina nano-particles, as proved by FTIR analysis.     

In Situ synthesis of poly(styrene–butylacrylate–acrylic acid) latex/barium sulfate nanocomposite and evaluation of their film properties

Barium sulfate nanocrystals of average 40 nm sizes were prepared by the micellar solution spray process. The influences of atomized impingement flow on nanoparticle formation and stabilization were inspected on the basis of Fourier transform infrared (FTIR), X‐ray diffraction, and transmission electron microscopy analysis. Poly(styrene–butylacrylate–acrylic acid) (PSBA) nanocomposites were synthesized by in situ copolymerization in the presence of 0.5–2.5% BaSO₄ nanoparticles. FTIR and atomic force microscopy analysis confirmed the uniform dispersion of 2% or less nano‐BaSO₄ within the PSBA matrix. The strength of interfacial adhesion between the nanoparticle and copolymer was examined on the basis of hydroscopicity, differential scanning calorimetry, thermogravimetric analysis, and universal testing machine analysis of nanocomposite film. The glass transition and thermal decomposition temperatures of PSBA latex were shifted toward higher temperatures by the restriction of nano‐BaSO₄ on its segmental and long‐range chain mobility. The well‐dispersed nano‐BaSO₄, with a larger fraction of immobilized copolymer on the pigment surface, improves the scratch and abrasion resistance, decreases the water uptake, and increases the tensile strength and elongation at break of the latex film within the specific loading. Thus, fabricating the PSBA/BaSO₄ nanocomposite presents an effective approach for development of latex coatings with enhanced performance. POLYM. COMPOS., 34:1670–1681, 2013. © 2013 Society of Plastics Engineers     

Coordinated control of TCSC and UPFC to aid damping oscillations in the power system

A valid damping of oscillations is an upcoming extensive challenge while maintaining the stability of the power system. This oscillation generally occurs due to the fluctuation raised, when two systems are interconnected. This paper addresses the oscillation occurred in the power system as the main challenge, which thus performs an effective simulation in 68-bus system. Here, it promotes a sufficient CC with two FACTS devices such as TCSC and UPFC, which are connected with PSS. Further, it adopts firefly algorithm to enable the CC among the FACTS devices. To the next of the simulation, this paper compares the performance of the FF- CC with conventional optimisations include GSO, PSO, GA and ABC algorithms to enable CC. Further, it provides a detailed analysis of the impact of PSS and loading effects on CC. As a result, the performance of FF-CC hands over the stable power system with powerful damping of oscillations, after comparing it with the existing methods.

Abbreviations: ABC, Artificial Bee Colony; ICA, Imperialist Competitive Algorithm; AVR, Automatic Voltage Regulators; NETS, New England test system; BFOA, Bacteria Foraging Optimization Algorithm; NYPS, New York power system; BSO, Bacterial Swarm Optimization; PSO, Particle Swarm Optimization; CC, Coordinated Control; PSS, Power System Stabilizers; COA, Chaotic Optimization Algorithm; STATCOM, Static Synchronous Compensator; CS, Cuckoo Search; SSSC, Static Synchronous Series Compensator; FACTS, Flexible Alternating Current Transmission System; SVC, Static Var Compensator; GA, Genetic Algorithm; TCSC, Thyristor Controlled Series Capacitor; GSO, Gravitational Search Algorithm; UPFC, Unified Power Flow Controller