Showing papers by "Sathyabama University published in 2008"
TL;DR: In this paper, the interaction of single-cell protein of Spirulina platensis with aqueous AgNO3 and HAuCl4 was investigated for the synthesis of Ag, Au and Au core.
Abstract: Interaction of single-cell protein of Spirulina platensis with aqueous AgNO3 and HAuCl4 was investigated for the synthesis of Ag, Au and Au core—Ag shell nanoparticles. Biological reduction and extracellular synthesis of nanoparticles were achieved in 120 h at 37 °C at pH 5.6. The nanometallic dispersions were characterized by surface plasmon absorbance measuring at 424 and 530 nm for Ag and Au nanoparticles, respectively. For bimetallic nanoparticles, absorption peak was observed at 509, 486 and 464 nm at 75:25, 50:50 and 25:75 (Au:Ag) mol concentrations, respectively. High-resolution transmission electron microscopy showed formation of nanoparticles in the range of 7–16 (silver), 6–10 (gold) and 17–25 nm (bimetallic 50:50 ratio). XRD analysis of the silver and gold nanoparticles confirmed the formation of metallic silver and gold. Fourier transform infrared spectroscopic measurements revealed the fact that the protein is the possible biomolecule responsible for the reduction and capping of the biosynthesized nanoparticles.
318 citations
TL;DR: In this article, the effect of welding speed and tool pin profile on FSP zone formation in AA2219 aluminium alloy has been analyzed macroscopically and the tensile properties of the joints have been evaluated and correlated with the formation.
318 citations
TL;DR: In this article, a second-order model has been established between the cutting parameters and surface roughness using response surface methodology, and the predicted values and measured values are fairly close, which indicates that the developed model can be effectively used to predict the surface rouness in the machining of GFRP composites.
Abstract: This paper discusses the use of Taguchi and response surface methodologies for minimizing the surface roughness in machining glass fiber reinforced (GFRP) plastics with a polycrystalline diamond (PCD) tool. The experiments have been conducted using Taguchi’s experimental design technique. The cutting parameters used are cutting speed, feed and depth of cut. The effect of cutting parameters on surface roughness is evaluated and the optimum cutting condition for minimizing the surface roughness is determined. A second-order model has been established between the cutting parameters and surface roughness using response surface methodology. The experimental results reveal that the most significant machining parameter for surface roughness is feed followed by cutting speed. The predicted values and measured values are fairly close, which indicates that the developed model can be effectively used to predict the surface roughness in the machining of GFRP composites. The predicted values are confirmed by using validation experiments.
236 citations
TL;DR: From the present study, it is obvious that there might be some chances of structural modification of components in tea due to enzymes liberated by bacteria and yeast during kombucha fermentation which results in better scavenging performance on nitrogen and superoxide radicals, and poor scavengingperformance on hydroxyl radicals.
223 citations
TL;DR: In this article, the use of response surface methodology for minimizing the surface roughness in machining titanium alloy, a topic of current interest, has been discussed in the context of machining.
Abstract: The use of response surface methodology for minimizing the surface roughness in machining titanium alloy, a topic of current interest, has been discussed in this article. The surface roughness model has been developed in terms of cutting parameters such as cutting speed, feed, and depth of cut. Machining tests have been carried out using CVD (TiN–TiCN–Al2O3–TiN) coated carbide insert under different cutting conditions using Taguchi's orthogonal array. The experimental results have been investigated using analysis of variance (ANOVA). The results indicated that the feed rate is the main influencing factor on surface roughness. Surface roughness increased with increasing feed rate, but decreased with increasing cutting speed and depth of cut. The predicted results are fairly close to experimental values and hence, the developed models can be used for prediction satisfactorily.
119 citations
TL;DR: In this paper, the effectiveness of the EDM process with tungsten carbide and cobalt composites is evaluated in terms of the material removal rate and the surface finish quality of the workpiece produced.
Abstract: Electrical discharge machining (EDM) is a process for shaping hard metals and forming deep and complex shaped holes by arc erosion in all types of electro conductive materials. In the present work, the effectiveness of the EDM process with tungsten carbide and cobalt composites is evaluated in terms of the material removal rate and the surface finish quality of the workpiece produced. The objective of this research is to study the influence of operating parameters of EDM such as pulse current, pulse on time, electrode rotation and flushing pressure on material removal rate and surface roughness. The experimental results are used to develop the statistical models based on second order polynomial equations for the different process characteristics. The non-dominated sorting genetic algorithm (NSGA-II) has been used to optimize the processing conditions. A non-dominated solution set has been obtained and reported.
111 citations
TL;DR: In this paper, the effect of cutting parameters on drilling such as spindle speed, feed, and their interactions are studied in detail, and the adequacies of the developed models have been verified by calculating correlation coefficient.
Abstract: Composite materials are used in varieties of applications and are mainly used in structural components. Drilling is one of the important operations in composite structure, often a final operation during assembly. Delaminations in drilling of composite structures are a serious problem and lead to rejection and impose heavy loss. In the present investigation, delamianation associated with drilling has been studied using experimental design approach. Two different cutting tools were tried for experimentation. The experiments were conducted by using high-speed steel-made twist drill and 4-flute cutter. Empirical models were developed for predicting delamination factor in drilling GFRP composites. Regression analysis and analysis of variance (ANOVA) were used for analysis. The adequacies of the developed models have been verified by calculating correlation coefficient. The effect of cutting parameters on drilling such as spindle speed, feed, and their interactions are studied in detail.
108 citations
TL;DR: In this paper, a mathematical model was developed to predict tensile properties of pulsed current GTA welded titanium alloy weldments with a 99% confidence level using ANOVA technique.
84 citations
TL;DR: In this paper, an experimental investigation on machining of fabricated silicon carbide particle reinforced aluminium metal matrix (A356/SiC/20p) composites by poly crystalline diamond (PCD) inserts is presented.
Abstract: The paper presents the experimental investigation on machining of fabricated silicon carbide particle reinforced aluminium metal matrix (A356/SiC/20p) composites by poly crystalline diamond (PCD) inserts. Experiments were conducted on lathe at various cutting conditions. The parameters considered for the experiments were cutting speed, feed and depth of cut. The response considered for the analysis was surface roughness. An empirical model has been developed for predicting the surface roughness in machining of A356/SiC/20p composites. Response surface regression and analysis of variance (ANOVA) are used in order to study the effects of machining parameters. Optimum machining condition for minimizing the surface roughness is determined using desirability function approach. The influences of different parameters in machining Al/SiC particulate composite have been analyzed in detail.
81 citations
TL;DR: In this article, an attempt has been made to develop an empirical relationship between FSW variables to predict tensile strength of the friction stir welded AA2219 aluminum alloy, where four factors, five levels central composite design have been used to minimize number of experimental conditions.
Abstract: AA2219 aluminum alloy (Al-Cu-Mn alloy) has gathered wide acceptance in the fabrication of lightweight structures requiring a high strength-to-weight ratio and good corrosion resistance. Friction stir welding (FSW) process is an emerging solid state joining process in which the material that is being welded does not melt and recast. This process uses a nonconsumable tool to generate frictional heat in the abutting surfaces. The welding parameters such as tool rotational speed, welding speed, axial force, etc., and tool pin profile play a major role in deciding the joint strength. An attempt has been made to develop an empirical relationship between FSW variables to predict tensile strength of the friction stir welded AA2219 aluminum alloy. To obtain the desired strength, it is essential to have a complete control over the relevant process parameters to maximize the tensile strength on which the quality of a weldment is based. Therefore, it is very important to select and control the welding process parameter for obtaining maximum strength. To achieve this various prediction methods such as response surface method (RSM), analysis of variance (ANOVA), Student’s t-test, coefficient of determination, etc., can be applied to define the desired output variables through developing mathematical models to specify the relationship between the output parameters and input variables. Four factors, five levels central composite design have been used to minimize number of experimental conditions. The developed mathematical relationship can be effectively used to predict the tensile strength of FSW joints of AA2219 aluminum alloy at 95% confidence level.
75 citations
TL;DR: In this paper, a tool in artificial intelligence is used for the prediction of cutting parameters in turning titanium alloy (Ti-6Al-4V) and the parameters considered in this study are cutting speed, feed, and the depth of cut.
Abstract: Titanium alloys are utilized in many engineering fields such as chemical, industrial, marine, and aerospace due to their unique properties. Machining of these materials causes severe problems. At high temperatures, they become chemically active and tend to react with tool materials. In the present study, fuzzy logic (a tool in artificial intelligence) is used for the prediction of cutting parameters in turning titanium alloy (Ti-6Al-4V). The parameters considered in this study are cutting speed, feed, and the depth of cut. Fuzzy rule-based modeling is employed for prediction of tool flank wear, surface roughness, and specific cutting pressure in machining of titanium alloy. These models can be effectively used to predict the tool flank wear, surface roughness, and specific cutting pressure in machining of titanium alloys. Analysis of the influences of the individual important machining parameters on the responses have been carried out and presented in this study.
01 Jul 2008
TL;DR: Tungsten carbide/cobalt (WC/Co) cemented carbide is one of the important composite materials that are used in the manufacture of cutting tools, dies, and other special tools as mentioned in this paper.
Abstract: Tungsten carbide/cobalt (WC/Co) cemented carbide is one of the important composite materials that are used in the manufacture of cutting tools, dies, and other special tools. It has high ha...
TL;DR: In this article, a mathematical model has been developed with the response surface method (RSM) to predict impact toughness of pulsed-current gas tungsten arc-welded titanium alloy weldments.
Abstract: Titanium (Ti-6Al-4V) alloy has gathered wide acceptance in the fabrication of lightweight structures requiring a high strength-to-weight ratio, such as in the applications of transportable bridge girders, military vehicles, road tankers, and space vehicles. The preferred welding process for welding titanium alloy is frequently gas tungsten arc welding (GTA) due to its comparatively easier applicability and better economy. In the case of single-pass gas tungsten arc welding of thinner section of this alloy, the pulsed current has been found beneficial due to its advantages over the conventional continuous-current process. In this investigation, an attempt has been made to develop a mathematical model to predict impact toughness of pulsed-current gas tungsten arc-welded titanium alloy weldments. Four factors, five level, central composite, rotatable design matrix is used to optimize the required number of experiments. A mathematical model has been developed with the response surface method (RSM). The adequacy of the model has been checked using ANOVA technique. By using the developed mathematical model, impact toughness of the joints can be predicted with 99% confidence level.
TL;DR: In this article, the authors discuss about improvement of damping capability of boring tools and suppression of chatter using Magnetorheological (MR) damper and show that MR damper application reduces the possibility of chatter and improves the stability of boring operation.
Abstract: This present study discusses about improvement of damping capability of boring tools and suppression of chatter using Magnetorheological (MR) damper. For the design and optimization of MR fluid damper volume constrained optimization methodology using ANSYS magnetic finite element routines were executed. Optimized design of MR damper was fabricated and its effect in boring operation has been investigated using an experimental setup. Experimental results were analyzed with the help of Auto-Regressive (ARX) models. Results show that MR damper application reduces the possibility of chatter and improves the stability of boring operation.
TL;DR: In this article, the influence of cutting parameters on surface roughness parameters such as Ra, Rt, Rq, Rp and R3z in turning of glass fiber reinforced composite materials is investigated.
TL;DR: The methanol extract of Pterocarpus santalinus showed significant DPPH radical inhibition (83.4% at 25 mg/ml concentration).
Abstract: Methanol extract of Pterocarpus santalinus (leaves) was evaluated for HPTLC finger print, phytochemical analysis and antioxidant activity. Preliminary phytochemical screening (HPTLC fingerprint) revealed the presence of terpenoids, steroids, flavonoids and carbohydrates. DPPH assay was used to determine the antioxidant property. The methanol extract of Pterocarpus santalinus showed significant DPPH radical inhibition (83.4% at 25 mg/ml concentration). The study reveals the potency of Pterocarpus santalinus as antioxidant source.
TL;DR: In this paper, the influence of different lighting conditions on the optical surface finish parameter is investigated and the results of both the approaches confirm that grazing angle is the most influencing factor affecting the image parameter.
Abstract: In the evaluation of surface roughness by machine vision technique, the scattered light pattern reflected from the machined surface is generally captured and optical surface finish parameters from the images are correlated with the actual roughness. Capturing of the image at appropriate conditions is required for the good correlation of the optical parameters with the roughness. Lighting conditions is a major factor that influences the image pattern and hence the optical parameters. In this work the lighting conditions like grazing angle, the light to specimen distance, the orientation of the striations on the surface to the light are varied and its influence on the optical surface finish parameter are studied. A plan of experiments based on the techniques of Taguchi was designed and executed for conducting the trials and to obtain valid conclusions. The analysis of variance and the signal to noise ratio of robust design are employed to investigate the influence of different lighting conditions on the optical surface finish parameter. The results of both the approaches confirm that grazing angle is the most influencing factor affecting the image parameter.
TL;DR: In this paper, a statistical model is proposed for use in predicting the delamination in drilling glass fiber reinforced plastic composites, and the results proved that HSM is a technology capable of producing lower damage level in drilling of GFRP composites.
Abstract: Drilling is one of the machining processes most widely applied to composite materials; nevertheless, these materials are prone to delaminate when subjected to stress concentration during machining operations. The damage induced by this operation may reduce the component performance drastically. The present study aims at high speed machining (HSM) to realize high performance drilling of glass fiber reinforced plastics (GFRP) with reduced delamination. The effects of feed rates, spindle speeds and the geometrical characteristics of the drill on the resulting delamination factor values are comparable regardless of the drill point angle used. A statistical model is proposed for use in predicting the delamination in drilling glass fiber reinforced plastic composites. The results proved that HSM is a technology capable of producing lower damage level in drilling of GFRP composites.
TL;DR: In this article, aqueous extract of Cadaba fruticosa (leaves) was subjected for hypoglycemic activity in wistar rats (160-200 g), and the oral administration of leaf extracts at dose 1000 mg/kg led to a significant blood glucose reduction.
Abstract: Alcohol and aqueous extract of Cadaba fruticosa (leaves) were subjected for hypoglycemic activity in wistar rats (160-200 g). The oral administration of leaf extracts at dose 1000 mg/kg led to a significant blood glucose reduction. Phytochemical analysis of alcohol extract revealed the presence of terpenoids, flavanoids, steroids, proteins, alkaloids, gums, sugars and saponins but negative result was observed in aqueous extract except terpenoids, flavonaids, proteins, furans, gums and sugars. This study brings out the evidence regarding pharmacological and phytochemical activities of C. fruticosa .
01 Nov 2008
TL;DR: In this paper, the authors discuss the current trends in the design of microstrip M patch antenna intended for various applications and it is a innovative nature never tried out earlier, which opens up a new avenue for different frequency ranges and new applications yet easily realizable with maximum advantages.
Abstract: In this paper, we are going to discuss about the current trends in the design of Microstrip M patch antenna intended for various applications and it is a innovative nature never tried out earlier. This opens up a new avenue for different frequency ranges and new applications yet easily realizable with maximum advantages. In rectangular micro strip patch antennas [RMSA] with negative capacitance and inductance for bandwidth enhancement. Micro strip antennas have been found favorable because they are : 1. low profile 2. inexpensive to manufacture and compatible with monolithic microwave integrated circuit designs (MMIC). But they also suffer due to (a) low efficiency (b) Narrow impedance band width. Input impedance of an antenna tends to be sensitive to changes in frequency, hence deviation of the antennas input impedance from a real fixed value often determines the operational range of the antenna. Input impedance of MSDA depends on its with geometrical shape, dimension and the feed type. Therefore antenna input impedance is an important design parameter which controls the radiated power and the impedance bandwidth. In most application, bandwidth limitations occur due to an impedance mismatch. In the respect micro strip antenna have narrow bandwidth because of heavy reactance. As micro strip antennas have found wide variety of application areas, a number of techniques are evolved to improve its limited bandwidth. A straight forward application to improve the bandwidth is increasing the thickness of substrate supporting the micro strip patch. However limitation shall exist on the ability to effectively feed the patch on a thick substrate and the radiation efficiency can degrade with increasing substrate thickness. Techniques for overcoming this band limiting problems can be achieved by using parasitic terms elements, external matching and separating the feed and antenna. Proximity coupling method uses an impedance matching stub connected to the feed line achieving 13% bandwidth. A broadband rectangular patch antenna with a pair of vide slits at near the resonance frequency improves to 24% bandwidth. Bandwidth of 10-12% can be obtained using passive coplanar matching network. Impedance bandwidth of 60% was achieved using the L and T slots in the micro strip slot antenna, however gain and radiation pattern are distorted. Using aperture coupled antenna BW large than 20% and cross polarization level lower than -30 db can be achieved. Bandwidth of circular loop antenna can be significantly increased when one more parasitic loop in added.
TL;DR: In this paper, the effects of feed speed, rotational speed and drill geometry on the resulting delamination factor are comparable in spite of the drill point angle used, and a mathematical model is proposed to predict delamination in drilling glass fiber-reinforced plastic composites.
Abstract: Fiber-reinforced composites are widely recognized for their superior mechanical properties and advantages for applications in aerospace, defence and transportation sectors. Delamination is a problem associated with drilling fiber-reinforced composite materials. In this work, the effects of feed speed, rotational speed and drill geometry on the resulting delamination factor are comparable in spite of the drill point angle used. A mathematical model is proposed to predict delamination in drilling glass fiber-reinforced plastic composites.
TL;DR: In this article, the spectral responses of most alike coastal features such as aquaculture plots, saltpans, sandy beaches, built-up areas and fly ash dumpsites show mix-ups in the VIS and NIR band responses.
Abstract: Mapping and classification of coastal features from visible (VIS) and near-infrared (NIR) bands of remote sensing satellite data is less accurate (∼67 to 70 only) than land features due to confusing spatial and spectral characteristics among several contiguous shallow water features. Our study of spectral responses of most alike coastal features such as aquaculture plots, saltpans, sandy beaches, built-up areas and fly ash dumpsites show mix-ups in the VIS and NIR band responses. Albeit, the VIS (green) and short-wavelength infrared (SWIR) bands show subtle distinctions which help to more accurately and automatically perform digital classification of these features with a reasonable accuracy of >95%.
TL;DR: In this paper, the effect of different parameters on cutting forces were analyzed and presented in a model to predict the cutting forces in turning of GFRP composites using CBN tools.
Abstract: GFRP composites find diverse applications in many engineering fields. For certain applications, the use of composites rather than metals has in fact resulted in savings of both cost and weight. The usage in many fields demands several machining operations to be performed on GFRP composites. As such, the present paper investigates the effect of cutting force in the turning of GFRP pipes using CBN tools. Experiments are conducted on a lathe using the central composite design technique. A model is developed to correlate the cutting parameters with cutting force, using response surface methodology. The results indicate that the developed model is suitable for prediction of cutting forces in turning of GFRP composites. The effect of different parameters on cutting forces are analyzed and presented in this study.
TL;DR: A ketene based Low molecular weight polymer (LMKP) having ester functional group was prepared using glycine through surface initiated anionic polymerization to yield semi-IPN nanohydrogels (NHG).
Abstract: A ketene based Low molecular weight polymer (LMKP) having ester functional group was prepared using glycine through surface initiated anionic polymerization. NMR, ATR-FTIR & SEC were used to characterize the LMKP. The LMKP and acrylamide (AAm) were co-polymerised in methyl ethyl ketone to yield semi-IPN nanohydrogels (NHG). Benzoyl peroxide (BPO) was used as an initiator and N,N-methylene bisacrylamide (MBA) as crosslinking agent. Formation of NHG was confirmed through frequency shift in LMKP and poly acrylamide (PAAm) in FTIR spectroscopy. Photon correlation spectroscopy reveals that the sizes of the NHG were in the range of 140-225 nm and Transmission Electron Micrograph (TEM) also confirms the nano dimension of NHG. Biocompatibility of the NHG was confirmed through the cytotoxicity analysis. The swelling and diffusion behaviour of NHG, prepared under various formulations, were evaluated. The swelling pattern of NHG was studied at different pH conditions. The drug delivery capacity of NHG was investigated using ciprofloxacin as a model drug. The drug release kinetics of NHG suggested their anomalous (non-fickian) behaviour.
TL;DR: In this article, the authors developed mathematical models to predict grain size and hardness of argon tungsten pulse current arc welded titanium alloy weldments with a 99% confidence level.
TL;DR: In this article, a mathematical model has been developed to predict corrosion rate of gas tungsten arc welded titanium alloy by incorporating pulsed current parameters such as peak current, back ground current, pulse frequency and pulse-on-time.
Abstract: The preferred process for welding titanium alloy is frequently gas tungsten arc (GTA) welding due to its comparatively easier applicability and better economy. Weld fusion zones of this alloy typically exhibit coarse columnar grains and lead to inferior mechanical and metallurgical properties. In the case of single pass GTA welding of a thinner section of this alloy, the pulsed current has been found to be beneficial primarily due to grain refinement of the weld fusion zone over the conventional continuous current process. Fusion zone grain refinement is controlled by pulsed current parameters such as peak current, back ground current, pulse frequency and pulse-on-time. In this investigation, a mathematical model has been developed to predict corrosion rate of gas tungsten arc welded titanium alloy by incorporating pulsed current parameters. Four factors, five level, central composite, rotatable design matrix has been used to minimize the experimental conditions. A mathematical model has been developed by response surface method (RSM). The developed model has been optimized using genetic algorithm (GA) and contour plots to attain minimum corrosion rate in the weld fusion zone.
Proceedings Article•
01 Nov 2008TL;DR: There is a revolution in modern digital ICs &PCB designs and their usage triggers the need for better understanding of PCB design [ apart from digital circuit design ] in detail.
Abstract: There is a revolution in modern digital ICs &PCB designs and their usage triggers the need for better understanding of PCB design [ apart from digital circuit design ] in detail Design of digital circuits need special cares with respect to EMC and hence the associated mounting of components besides PCB design layout These aspects are addressed in this paper with Check list in the form of detailed design guidelines for both areas Also the current trend and future challenges in PCB design for next generation ELECTRONICS are discussed in brief
03 Apr 2008
TL;DR: In this paper, a neuro fuzzy based AC voltage controller is proposed to generate the firing pulses for appropriate thyristors for any given operating torque, speed of the motor and the load.
Abstract: Soft starters are used with induction motors in blowers, fans, pumps and the crane hoist drives. AC voltage controllers are used as soft starters in induction motors for starting and to adjust its speed. This paper presents a novel neuro fuzzy based AC voltage controller to generate the firing pulses for appropriate thyristors for any given operating torque, speed of the motor and the load. An ANFIS (Adaptive Neuro Fuzzy Inference System) model has been designed to achieve the proposed algorithm. MATLAB/SIMULINK package has been used to simulate the proposed method. Simulation results presented in this paper explain the advantages of proposed soft starting method over conventional method. The advantages of proposed method are its simplicity, stability, and accuracy and fast response.
TL;DR: In this paper, a mixed integer linear programming (MILP) model is developed and five different management strategies are tested to determine whether significant improvements might be realized from optimization of operation of the reservoir system.
Abstract: One of the methods for increasing productivity of water consumed in agriculture is by improved water supply management. This paper presents results from an optimization study of the Malampuzha irrigation project of the Bharathapuzha river basin of Kerala in India. The objective of this study is to determine whether significant improvements might be realized from optimization of operation of the reservoir system. To do this a mixed integer linear programming (MILP) model is developed and five different management strategies are tested. The result indicates that a management strategy with deficit irrigation by supplying less water in non-critical growth period and maximum water during stress sensitive periods is a best viable solution for better performance. A MILP model, rather than a linear programming (LP) model, is used to ensure that the reservoir does not spill before reaching its capacity.
01 Dec 2008
TL;DR: In this paper, an adaptive neuro-fuzzy inference system (ANFIS) was used to estimate the stator resistance of a squirrel cage induction motor with respect to the temperature.
Abstract: This paper presents application of adaptive neuro-fuzzy inference system (ANFIS) into a squirrel cage induction machine towards modeling, control and estimation. This paper contributes (i) Development of a simple and more realistic model of the induction motor using ANFIS. Using ANFIS, the parameter sets of the motor model are estimated. The simplified model contains eleven estimated parameters. In this paper, a new estimation technique for modeling of induction motor is presented. The identified model can be utilized for electric drives. (ii) Speed, torque and flux control using direct torque control (DTC) algorithm with ANFIS (iii) Design of Estimator through ANFIS which estimates the stator resistance with reference to the temperature when the DTC algorithm is involved. Better estimation of stator resistance results in the improvements in induction motor performance using DTC thereby facilitating torque ripple minimization. The values of stator voltage (Vs), stator current (Is) and rotor angular velocity (omegar) are taken from the free acceleration test data of 5 HP motor for simulation.