Showing papers by "National Institute of Technology, Silchar published in 2011"

Rice Husk and Its Ash as Low-Cost Adsorbents in Water and Wastewater Treatment

Abstract: Rice husk, which is a relatively abundant and inexpensive material, is currently being investigated as an adsorbent for the removal of various pollutants from water and wastewaters. Various pollutants, such as dyes, phenols, organic compounds, pesticides, inorganic anions, and heavy metals can be removed very effectively with rice husk as an adsorbent. This article presents a brief review on the role of rice husk and rice husk ash in the removal of various pollutants from wastewater. Studies on the adsorption of various pollutants by rice husk materials are reviewed and the adsorption mechanism, influencing factors, favorable conditions, etc., discussed in this article. It is evident from the review that rice husk and its ash can be potentially utilized for the removal of various pollutants from water and wastewaters.

Blending of additives with biodiesels to improve the cold flow properties, combustion and emission performance in a compression ignition engine—A review

Abstract: Biodiesel is widely accepted as comparable fuel to diesel in compression ignition engines It offers many advantages including: higher cetane number; reduced emissions of particulates, NO x , SO x , CO, and hydrocarbons; reduced toxicity; improved safety; and lower lifecycle CO 2 emissions A characteristic of biodiesel limiting its application is its relatively poor low-temperature flow properties Improvement of its low temperature flow characteristic still remains one of the major challenges when using biodiesel as an alternative fuel for diesel engines The biodiesel fuels derived from fats or oils with significant amounts of saturated fatty compounds display higher cloud points and pour points thus limiting their applications The cold flow properties of different biodiesel were evaluated with various additives towards the objectives of improving the viscosity, pour point and cloud point Methanol ethanol, kerosene, Mg additives, etc have been tried many researchers to improve the cold flow behavior of biodiesels Varying results of improvement in cold flow properties have been obtained by using different additives Similarly different additives have been used by different researchers to improve the performance of a compression ignition engine and its emissions This review has been taken up to identify the various additives used to improve the cold flow properties of biodiesels and improve the performance of a diesel engine and its emissions while using additive blended biodiesels The review concludes that the additives usage in biodiesel is inseparable both for improving the cold flow properties and for the better engine performance and emission control and further research is needed to develop biodiesel specific additives

Structural, electrical and optical studies on spray-deposited aluminium-doped ZnO thin films

Abstract: Thin films of zinc oxide (ZnO) were deposited on cleaned glass substrates by chemical spray pyrolysis technique using Zn(CH3COO)2 as precursor solution. Also, aluminium-doped thin films of ZnO were prepared by using AlCl3 as doping solution for aluminium. The dopant concentration [Al/Zn atomic percentage (at%)] was varied from 0 to 1.5 at% in thin films of ZnO prepared in different depositions. Structural characterization of the deposited films was performed with X-ray diffraction (XRD) studies. It confirmed that all the films were of zinc oxide having polycrystalline nature and possessing typical hexagonal wurtzite structure with crystallite size varying between 100.7 and 268.6 nm. The films exhibited changes in relative intensities and crystallite size with changes in the doping concentration of Al. The electrical studies established that 1 at% of Al-doping was the optimum for enhancing electrical conduction in ZnO thin films and beyond that the distortion caused in the lattice lowered the conductivity. The films also exhibited distinct changes in their optical properties at different doping concentrations, including a blue shift and slight widening of bandgap with increasing Al dopant concentration.

Surface Integrity of C-40 Steel Processed with WC-Cu Powder Metallurgy Green Compact Tools in EDM

Abstract: Electric discharge machining (EDM) is an electrothermal process where recast layer on the machined surface and heat-affected (HAZ) zone just below the machined surface are common phenomena. Thus, the assessment of surface integrity in EDM is a very important task. In this study, an attempt was made to modify the surface integrity of C-40 steel in EDM. WC-Cu powder metallurgy (P/M) green compact tools were used so that the tool material could be transferred to the work surface and thereby the surface characteristics could be altered. WC was used as tool material because of its ability to produce a hard layer over the work surface. A detailed experimental study was performed. The effect of various process parameters on the surface characteristics were presented with the support of analyses such as material transfer rate (MTR), tool wear rate (TWR), surface roughness, optical microscopy, scanning electron microscopy (SEM), energy dispersive x-ray (EDX), x-ray diffraction (XRD), microhardness testing, etc. It...

Taguchi analysis of surface modification technique using W-Cu powder metallurgy sintered tools in EDM and characterization of the deposited layer

Abstract: The present study describes an experimental research on surface modification during electrical discharge machining (EDM) by depositing a hard layer over the work surface of C-40 grade plain carbon steel using specially prepared powder metallurgy compact tools The investigated process parameters were composition, compaction pressure, sintering temperature, pulse on-time, peak–current setting, and duty factor Measurements of deposited layer thickness, mass transfer rate, tool wear rate, surface roughness and microhardness were undertaken on the EDM-ed specimens Different studies like X-ray diffraction, optical microscopy, scanning electron microscopy, and energy dispersive X-ray spectroscopy were carried out to ascertain the characteristics of the deposited layer on the work surface These analyses confirmed the presence of the tool materials in the work surface layer At first, an L-16 orthogonal array was applied as Taguchi DOE technique and the ANOVA was done to study the effects of pertinent process parameters An optimum condition was achieved using overall evaluation criteria Later on, a detailed study was carried out to get a smooth and regular deposition of material The characterization of the deposited layer is presented The deposited layer with a wide range of average layer thickness of 3–785 μm, enriched with tool materials (W and Cu) and with the formation of tungsten carbide, and having microhardness of 981–1275 GPa at the hardest zone was successfully deposited over the work surface

Jatropa—The future fuel of India

Abstract: For India, there is a need to take a mission approach to explore the possibility of using straight/unmodified vegetable oils, their blends or biodiesels and their blends with mineral diesel as alternative fuel in order to achieve the twin objectives of reducing the emissions from the diesel engine and to increase the energy security of the country. Jatropa seems to the answer for India's energy woes. Millions of hectares of waste land is available in India and out of which about 33 million hectares of wasteland has been found to be suitable for Jatropa cultivation. Jatropa seems to be perfectly suited for India. However, all is not well for Jatropa in India. There are many social, technical and political issues to be sorted out before the dream of energy security through Jatropa cultivation could be realized. These problems and suggested solutions are dealt in detail in this paper. The suitability of Jatropa oil blends and Jatropa biodiesel blends in running of compression ignition has been evaluated and found that the performance of Jatropa oil and Jatropa biodiesel blends is very close to performance of diesel in the compression ignition engine. The break thermal efficiency, break specific energy consumption, CO, UBHC, NOx emissions have been experimentally determined. A SWOT analysis of Jatropa with specific reference to Indian conditions has been carried out and found that Jatropa indeed is a plant which can make the Indian dream of self-sufficiency in energy—a reality.

A real-integer-discrete-coded particle swarm optimization for design problems

Abstract: The successful application of particle swarm optimization (PSO) to various real-valued problems motivates to develop some integer-coded versions of PSO for working directly with integer and discrete variables of a problem. However, in most of such works, actually a real-valued solution is just converted into a desired integer-valued solution by applying some posterior decoding mechanisms, while some problem-specific integer-coded versions of PSO are proposed in others. In this article, a novel version of PSO of general form is proposed, which can work directly with real, integer and discrete variables of a problem without any conversion. Quite satisfactory performance is obtained by applying the proposed PSO to some classical mechanical design problems of different nature.

Activated Neem Leaf: A Novel Adsorbent for the Removal of Phenol, 4-Nitrophenol, and 4-Chlorophenol from Aqueous Solutions

Abstract: The adsorption of three phenolic compounds, phenol (P), 4-nitrophenol (4-NP), and 4-chlorophenol (4-CP), on activated neem leaves (ANL) was investigated from simulated wastewater in batch as well as fixed bed mode. The effect of various operating parameters on adsorption such as adsorbent dose, solution pH, contact time, and temperature effect was monitored, and optimal experimental conditions were determined. The Langmuir, Freundlich, Redlich−Peterson, Dubunin–Radushkevich, and Temkin models were applied to describe the adsorption isotherms in the three systems. The goodness of curve fitting in the various models was done in accordance with linear regression coefficients and various error functions. Thermodynamic parameters such as the Gibbs free energy change, enthalpy change, and entropy change of the adsorption processes were also evaluated for the three different phenolic systems. The thermodynamic study shows the exothermic nature of the adsorption. The pseudofirst-order, pseudosecond-order, and Elo...

PSO based frequency controller for wind-solar-diesel hybrid energy generation/energy storage system

Abstract: The aim of this paper is the tuning of a PI controller using PSO techniques for autonomous hybrid energy generation/energy storage system. The autonomous hybrid generation system consisting of wind turbine generators (WTG), solar photovoltaic (PV), diesel engine generators (DEG), fuel cells (FC), battery energy storage system (BESS), ultra capacitors ( UC) and aqua electrolyzer (AE) has been considered for simulation studies. The power system frequency deviates for sudden changes in load or generation or the both. The comparative performance of the controllers installed to alleviate this frequency deviation for different hybrid systems, is carried out using time domain simulation. In practice, PI controller is tuned manually which is difficult and time consuming. The computational intelligence has opened paths to a new generation of advanced process control. Here, PSO is used for optimization of controller gains of the proposed hybrid system. The simulation results demonstrate the effectiveness of the PSO based controller in terms of reduced settling time, overshoot and oscillations. The results are compared with conventional controller.

Graph partitioning by multi-objective real-valued metaheuristics: A comparative study

Abstract: The graph partitioning is usually tackled as a single-objective optimization problem. Moreover, various problem-specific versions of different algorithms are proposed for solving this integer-valued problem, thus confusing practitioners in selecting an effective algorithm for their instances. On the other hand, although various metaheuristics are currently in great consideration towards different problem-domains, these are yet to be investigated widely to this problem. In this article, a novel attempt is made to investigate whether some common and established metaheuristics can directly be applied to different search spaces, instead of going through various problem-specific algorithms. For this, some mechanisms are proposed for handling the graph partitioning problem by general multi-objective real-valued genetic algorithm, differential evolution, and particle swarm optimization. Some algorithmic modifications are also proposed for improving the performances of the metaheuristics. Finally, the performances of the metaheuristics are compared in terms of their computer memory requirements, as well as their computational runtime and solution qualities based on some test cases with up to five objectives.

Power system fault detection classification based on PCA and PNN

Abstract: This paper presents a new approach for power system fault classification based on principal component analysis (PCA) and probabilistic neural network (PNN).the work presented in this paper is focused on identification of simple power system faults. The new model mainly includes three steps. Firstly wavelet transform is used to analyze power system fault signals, and distinguishing features are extracted from the result of wavelet transform. Secondly, principal-component analysis (PCA) is used to reduce the dimensionality of data set, mean while extract principal-components to describe nonstationary signals of the power system. Finally, use the principal-components as the input vectors of probabilistic neural network and classify the power system faults. The simulation results show the validity and efficiency of the proposed model.

CFD Analysis of Flow Physics and Aerodynamic Performance of a Combined Three-Bucket Savonius and Three-Bladed Darrieus Turbine

Abstract: In this paper, the performance of a combined three-bucket Savonius and three-bladed Darrieus turbine was analyzed computationally by using Fluent 6.2 CFD software. Two-dimensional steady-state CFD simulations were performed for without overlap, and with five overlaps namely 16.2%, 20%, 25%, 30%, and 35%. The flow physics of the combined turbine was analyzed with the help of pressure, velocity and vorticity contours. Further, the aerodynamic coefficients were evaluated with respect to angle of attack for various tip speed ratios. It was concluded that the power augmentation of the combined turbine occurred for low overlap in Savonius turbine due to high aerodynamic lift-to-drag coefficient of the Savonius turbine, caused by the increase of dynamic pressure from bucket-vortex interactions on the concave face of the returning bucket. And it also occurred for high aerodynamic lift-to-drag coefficient (14.5) of the Darrieus turbine from the increase of velocity difference across the Darrieus blade with small o...

A Joint DWT-DCT Based Robust Digital Watermarking Algorithm for Ownership Verification of Digital Images

Abstract: In this paper, a robust digital image watermarking algorithm based on joint Discrete Wavelet Transform and Discrete Cosine Transform (DWT-DCT) is proposed. The proposed system provides imperceptibility and higher robustness against common signal processing attacks. A binary watermarked image is embedded in certain subbands of a 3-level DWT transformed coefficients of a host image. Then, DCT coefficients of each selected DWT subband is computed. A randomly generated two-dimensional key is used to encrypt the watermark. This 2D key provides security to the image and ownership copyrights. The PN-sequences of the encrypted watermark bits are embedded in the coefficients of the corresponding DCT middle frequencies providing higher security. In extraction stage, the same approach as that of the embedding process is used to extract the DCT middle frequencies of each subband. Finally, correlation between mid-band coefficients and PN-sequences is calculated to determine watermark bit which is again post-processed by the two-dimensional key generated to derive the actual watermark. Experimental results show that the proposed method based on joint procedure of DWT-DCT may be used for watermarking the digital images.

Multiobjective Optimization of Pump-and-Treat-Based Optimal Multilayer Aquifer Remediation Design with Flexible Remediation Time

Abstract: Groundwater flow model MODFLOW 2000 and contaminant transport model MT3DMS 5.0 have been directly linked with nondominated sorting genetic algorithm (NSGA) II using a novel technique to solve a multiobjective pump-and-treat groundwater remediation problem. In this technique, the system simulators in their compiled forms are directly coupled with the optimization algorithm. The performance of the model has been evaluated on a multiobjective groundwater remediation problem based on a hypothetical confined multilayered aquifer under steady-state flow condition. Two conflicting objectives, viz, minimization of remediation cost and minimization of remediation time subject to upper and lower bounds on extraction rates, upper bounds on hydraulic heads, and contaminant concentration levels, are incorporated into the optimization formulation. Incorporation of discrete cost components into the objective cost function renders it to be discontinuous and nondifferentiable, and the resulting Pareto front exhibits disjo...

Chance-constrained multi-objective programming for optimal multi-layer aquifer remediation design

Abstract: Groundwater remediation works are expensive, complex in nature, and generally involve uncertain design parameters and multiple conflicting objectives. Reduction in remediation cost is, normally, the primary objective of optimal remediation designs. Remediation time has significant influence on remediation cost. The main contributions of this study are: development of a chance-constrained multi-objective programming (CCMOP) model, exploration of the significance of flexible remediation time on optimal remediation designs, and exploration of some basic characteristics of multi-objective optimization algorithms. The developed methodology excludes inferior yet optimal solutions from the set of possible solutions, identifies the ranges in which non-inferior solutions lie, and prevents one from making inferior decisions. It provides insightful information about the problem and simplifies the decision making process considerably. The results suggest that by avoiding the use of faulty remediation times, highly si...

Remote detection of illegal electricity usage employing smart energy meter - A current based technique

Abstract: At present, illegal usage of electricity is a serious problem facing the power industry in many countries. An efficacious and worthwhile solution to counteract this problem can be realized by using: a) already existing electrical network for communication i.e. PLC(Power Line communication) b) smart metering system. In the prototype of detection system presented in this paper, test signal at high frequency is transmitted through the network and software at supplier's end compares data with reference data. Based on the outcome of this comparison, it can remotely be detected if there is any illegal electricity usage or not. The study documented in this paper puts forward a new and unprecedented current-based technique to tackle the problem of illegal electricity usage. This paper reveals the existence of very small line current during the detection test which proves to be the key to unlock the problem of illegal electricity usage detection.

Fuzzy logic based improved active and reactive power control operation of DFIG for wind power generation

Abstract: The fuzzy-controllers are designed to tune along with the conventional PI-controllers for the vector control of active and reactive power of a wind-turbine driven DFIG under varying wind speed operation to optimize the power generation at specified power-factor. Initially, stator-flux-oriented vector control scheme is implemented using tuned active and reactive power PI-controllers for the rotor-side-converter. Then the fuzzy-controllers are also tuned along with conventional PI-controllers for the generated active power to track more precisely the reference power at specified power-factor in both sub-synchronous and super-synchronous modes of operations. The grid-side-converter is controlled in grid-voltage-oriented reference frame using dclink voltage PI-controller. Hysteresis current controlled based PWM switching of both rotor-side and grid-side converters ensure fast and accurate control of active and reactive power. Simulation results under varying wind conditions reveal that the additional fuzzy-controller improves the performance of variable speed wind power generating system using DFIG.

Comparative study of the performances of twisted two-bladed and three-bladed airfoil shaped H-Darrieus turbines by computational and experimental methods

Abstract: The vertical axis H-Darrieus turbines are simple in construction, self-starting, omni-directional, and self-regulating at all wind speeds. A comparative study of the performances of twisted two-bladed and three-bladed airfoil shaped H-Darrieus turbines was made. The models of the turbines were designed, fabricated, and tested in a subsonic wind tunnel. The power coefficients (C p ) and torque coefficients (C t ) were evaluated for ten numbers of height-to-diameter (H/D) ratios. Both C p and C t of the two-bladed turbine were higher than the three-bladed turbine. The maximum C p for the two-bladed turbine was 0.237 and that for the three-bladed turbine was 0.151. The performances of the turbines were also compared computationally through 2D steady-state CFD simulations using Fluent 6.2 software. The agreement between the computational and experimental C p was within ± 5.86%. The contour plots of static and dynamic pressures and velocity magnitudes were generated for chord Reynolds number of 8.5 × 10 4 . At any position on the blade, dynamic pressure, velocity and also the velocity gradient between the ends were higher for the two-bladed turbine than the three-bladed turbine.