Showing papers by "National Institute of Technology, Silchar published in 2015"

Cloud Computing Features, Issues, and Challenges: A Big Picture

Abstract: Since the phenomenon of cloud computing was proposed, there is an unceasing interest for research across the globe. Cloud computing has been seen as unitary of the technology that poses the next-generation computing revolution and rapidly becomes the hottest topic in the field of IT. This fast move towards Cloud computing has fuelled concerns on a fundamental point for the success of information systems, communication, virtualization, data availability and integrity, public auditing, scientific application, and information security. Therefore, cloud computing research has attracted tremendous interest in recent years. In this paper, we aim to precise the current open challenges and issues of Cloud computing. We have discussed the paper in three-fold: first we discuss the cloud computing architecture and the numerous services it offered. Secondly we highlight several security issues in cloud computing based on its service layer. Then we identify several open challenges from the Cloud computing adoption perspective and its future implications. Finally, we highlight the available platforms in the current era for cloud research and development.

Green synthesis of copper nanoparticles for the efficient removal (degradation) of dye from aqueous phase

Abstract: The present work reports the utilization of a common household waste material (fish scales of Labeo rohita) for the synthesis of copper nanoparticles. The method so developed was found to be green, environment-friendly, and economic. The fish scale extracts were acting as a stabilizing and reducing agents. This method avoids the use of external reducing and stabilizing agents, templates, and solvents. The compositional abundance of gelatin may be envisaged for the effective reductive as well as stabilizing potency. The mechanisms for the formation of nanoparticles have also been presented. The synthesized copper nanoparticles formed were predominantly spherical in nature with an average size of nanoparticles in the range of 25–37 nm. The copper nanoparticles showed characteristic Bragg’s reflection planes of fcc which was supported by both selected area electron diffraction and X-ray diffraction pattern and showed surface plasmon resonance at 580 nm. Moreover, the energy dispersive spectroscopy pattern also revealed the presence of only elemental copper in the copper nanoparticles. The prepared nanoparticles were used for the remediation of a carcinogenic and noxious textile dye, Methylene blue, from aqueous solution. Approximately, 96 % degradation of Methylene blue dye was observed within 135 min using copper nanoparticles. The probable mechanism for the degradation of the dye has been presented, and the degraded intermediates have been identified using the liquid chromatography-mass spectroscopy technique. The high efficiency of nanoparticles as photocatalysts has opened a promising application for the removal of hazardous dye from industrial effluents contributing indirectly to environmental cleanup process.

Photocatalytic-degradation and reduction of organic compounds using SnO2 quantum dots (via a green route) under direct sunlight

Abstract: SnO2 Quantum Dots (QDs) were synthesized by a facile and green biological method using sugar cane juice. The biomolecules present in the juice act as complexing as well as capping agents. No other external agents are required for the production of the SnO2 Quantum Dots (QDs). This method resulted in the formation of spherical SnO2 QDs having a particle size of ∼3–4.5 nm with a tetragonal crystal structure. The biosynthesized SnO2 QDs were characterized by transmission electron microscopy (TEM), selected area electron diffraction (SAED), Energy Dispersive Spectroscopy (EDS) and Fourier transform infrared spectroscopy (FT-IR). The optical properties were investigated using UV-visible spectroscopy. In the electronic spectra, a clear blue shift in the band gap energy is observed with a decrease in particle size. This is because of three dimensional quantum confinement effects. The biosynthesized SnO2 QDs act as an efficient photocatalyst for the degradation of rose bengal and methylene blue dye under direct sunlight. The catalytic activity of the biosynthesized SnO2 QDs were also evaluated by the conversion of p-nitrophenol to p-aminophenol in the presence of NaBH4. The reaction was carried out in a green solvent i.e., water at room temperature. It was observed that 99.5% of p-nitrophenol was reduced in the presence of SnO2 QDs within 60 min. These investigations indicate that the biosynthesized SnO2 QDs may be effective and potential materials for the elimination of hazardous pollutants from wastewater.

Computational analysis of flow physics of a combined three bladed Darrieus Savonius wind rotor

Abstract: A 3D unsteady computational Fluid Dynamics (CFD) model is utilized to investigate the aerodynamics of a combined three-bladed Darrieus Savonius wind rotor. Unsteady Reynolds-averaged Navier–Stokes (RANS) equations of the CFD software are modelled to obtain the fluid flow distributions. In this, initial unsteady effects of the flow interactions are covered to reach to the steady state condition at which the flow physics is analysed. The fluid zone has a large stationary domain and rotating sub-domain connected by a sliding mesh interface. The 3D wake structure of the combined rotor is analysed to understand the physical processes responsible for its power production in low wind speed regime. Steep Coanda like vortices are observed in the rotor wake that migrates from the downstream of Savonius rotor on to the downstream of Darrieus rotor. This effect results into compression of vortices on the downstream of Darrieus rotor thereby pushing the rotor in its rotation, hence augment power production. Presence of attached stall vortices on the Darrieus blades and increased concentration of vortices on the downstream of Darrieus rotor justifies the design of Darrieus rotor on top of Savonius rotor, which could be reflected in high value of power coefficient of the rotor. The outcome of this research would improve the viability of such combined rotor for its use in the built environment.

Incorporation of SnO2 nanoparticles in PMMA for performance enhancement of a transparent organic resistive memory device

Abstract: We report the electrical bistable characteristics of a hybrid polymer/inorganic nanocomposite device consisting of SnO2 nanoparticles (NPs) embedded in an insulating polymethylmethacrylate (PMMA) layer sandwiched between conductive indium tin oxide (ITO) and aluminium (Al) electrodes. X-ray diffraction measurements were performed for assessment of the crystallographic nature of SnO2 nanoparticles while the microstructural nature of SnO2 nanoparticles embedded in the PMMA matrix was confirmed using transmission electron microscopy. Detailed electrical characterizations suggested an influence of the NP concentration on the switching characteristics of the Al/SnO2-PMMA/ITO memory devices. The highest resistance ratio > 103 (Roff/Ron) was observed in a device with 2 weight% SnO2 NPs. The retention tests on the fabricated device demonstrated the consistency in current of the ON/OFF state even after 104 s. The conduction mechanisms of the fabricated nanocomposite based memory cell were discussed on the basis of experimental data using a charge trapping–detrapping mechanism in the NPs. Our findings offer a feasible and low cost chemical approach to fabricate a transparent and high density RS memory device.

A novel synthesis of Fe2O3@activated carbon composite and its exploitation for the elimination of carcinogenic textile dye from an aqueous phase

Abstract: The present work reports the synthesis of Fe2O3@activated carbon composite by the co-precipitation of iron salts onto activated carbon. The prepared composite was explored for the remediation of a carcinogenic textile dye, Remazol Brilliant Blue R (RBBR) from an aqueous solution. The surface morphology, composition and textural characteristics of the prepared magnetic composite (FAC) were investigated by FTIR, SEM-EDS, P-XRD, TEM, selected area electron diffraction (SAED), VSM, TGA, surface area and pore size measurements. TEM images showed that the prepared composites were wire-shaped. The saturation magnetization value (26.99 emu g−1) was sufficient for magnetic separation in wastewater treatment. The unique micro-/meso-porous structure, high surface area (1199 m2 g−1), and pore volume (0.9909 cm3 g−1) further enhance its utilization for the treatment of dye laden wastewater. The pseudo-second-order kinetic model with high correlation coefficients (R2 > 0.999) was suitable to described the process of RBBR adsorption onto FAC. The Langmuir model fitted the adsorption isotherm data better than the Freundlich, Temkin and DR model. Values of thermodynamic parameters (namely, ΔG°, ΔH° and ΔS°) indicated that the adsorption process was strongly dependent on the temperature of the aqueous phase, and it was spontaneous and exothermic in nature. Therefore, FAC composite displays main advantages of excellent dispersion, convenient separation and high adsorption capacity, which implies their potential application in environmental clean-up processes.

A novel and green process for the production of tin oxide quantum dots and its application as a photocatalyst for the degradation of dyes from aqueous phase.

Abstract: Green synthesis of SnO2 quantum dots (QDs) was developed by microwave heating method using the amino acids, namely, aspartic and glutamic acid. This method resulted in the formation of spherical SnO2 quantum dots with an average diameter less than the exciton Bohr radius of SnO2. The average diameter of SnO2 quantum dots formed using glutamic acid is ∼1.6 nm and is smaller than that formed using aspartic acid (∼2.6 nm). In the electronic spectra, a clear blue shift in the band gap energy from 4.33 to 4.4 eV is observed with a decrease in particle size (2.6–1.6 nm) due to three dimensional quantum confinement effects. The synthesized SnO2 QDs were characterized by transmission electron microscopy (TEM), selected area electron diffraction (SAED), X-ray diffraction (XRD) and Fourier transformed infrared spectroscopy (FT-IR). The optical properties were investigated using UV–visible spectroscopy. The synthesized SnO2 QDs act as an efficient photocatalyst in the degradation of Rose Bengal and Eosin Y dye under direct sunlight. For the first time, Rose Bengal dye was degraded using SnO2 QDs as a photocatalyst by solar irradiation.

An experimental investigation of surface modification of C-40 steel using W–Cu powder metallurgy sintered compact tools in EDM

Abstract: Surface modification is essential to enhance the surface properties of engineering components. This may be accomplished either in the form of altering the surface chemistry or by providing a protective layer over the work surface. In this paper, the surface modification phenomenon by depositing a protective layer over the work surface by electrical discharge machining (EDM) is presented. The potential of EDM, which is otherwise a useful non-conventional machining process, has been explored for surface alteration by depositing material over work surface using tungsten–copper (W–Cu) sintered powder metallurgy tools. The photographic presentation of the EDMed surface at different parameter settings is given. The variations of mass transfer rate (MTR), deposited layer thickness (LT), and average surface roughness (R a) with various parameter combinations are presented in graphical form and their effects are discussed. A wide spectrum of MTR ranging from nearly 1 to 191 mg/min and average surface roughness values ranging from 3 to 15 μm have been achieved. A wide range of deposited layers with thickness varying from 3 to 785 μm has been achieved by various combinations of process parameters. The microstructure of the deposited layers with microhardness at different zones is presented. It has been observed that the microhardness is gradually increasing from the base material to the deposited layer and its maximum value is found to be 15.7 GPa at the hardest zone. SEM, EDX, and XRD analyses has been also performed for further characterization of the deposited layer. A quantitative analysis of the layer has been carried out by EDX and it is found that the inner part of the layer is richer in tungsten than the superficial surface. This contributed towards the higher hardness of the layer at the core.

Computational Analysis of Hypersonic Combustor Using Strut Injector at Flight Mach 7

Abstract: Numerical analysis of the hypersonic combustion and flow structure through a scramjet engine at a flight Mach 7 with parallel fuel injection at different angles of attack, α = (−5°), 0°, and 5° have been studied in the present research article. The scramjet configuration incorporates an inlet angle of 8° compression ramp followed by an insulator and a divergent combustor for parallel injection. The shape of the strut is chosen such that it produces strong stream- wise vorticity and thus enhances the air/fuel mixing. These numerical simulations were aimed to study the flow structure, supersonic mixing, and combustion efficiency. For parallel injection investigation, the influence of the strut injector and the variation of angle of attack on the flow behavior in reacting cases have been studied. The shock structure and combustion phenomenon are affected by the combustor geometry, flight Mach number, and by the trajectory.

Control of Two-link 2-DOF Robot Manipulator Using Fuzzy Logic Techniques: A Review

Abstract: This paper reviews the literature on control of 2-DOF robot manipulator using fuzzy logic control (FLC). Different schemes of FLC laws are considered here. These are PID control, sliding mode control (SMC), and adaptive control. Importance of each control techniques with its advantages and disadvantages is discussed here. It is highlighted that the robustness of the system has improved considerably by using FLC than classical controller. A total of 65 papers were surveyed in this research area, covering contribution on each control technique for the 2-DOF robot manipulator for the time span of 1983–2014.