K. Senthil Kumar

Growth, microhardness, dielectric and photoconductivity characterization of a highly polarizable NLO material: Sodium p-nitrophenolate dihydrate (NO2-C6H4-ONa.2H2O)

Sodium p-nitrophenolate dihydrate (NPNa.2H2O) is a highly polarisable non linear optical material. It has a deff about 1.45 times than that of potassium titanyl phosphate. Single crystals of (NPNa.2H2O) have been grown successfully by slow solvent evaporation having water and methanol as solvent. The structure of the crystal is verified by single X-ray analysis. Optical absorption shows that the crystal is highly transparent between 1500 and 300 nm. Microhardness of the crystal is found to increases with increase in load and the hardness number is found to be high for methanol grown crystal as compared to the water grown crystal. Electrical conductivity as evaluated from the cole-cole plot is found to be 1.26 × 10−5 mho m−1. The dielectric constant of the crystal is low and independent at higher frequencies. The crystal has prominent photoconduction in the presence of trap energy levels formed by the Na+ ions. The SHG efficiency of the crystal is studied by performing Kurtz powder test and the results of scanning electron microscope analysis indicate that the major part of the crystal surface is free from inclusion and dislocation.

Intelligent Parallel Networks for Combustion Quality Monitoring in Power Station Boilers

This research work includes a combination of Fisher’s Linear Discriminant (FLD) analysis by combining Radial Basis Function Network (RBF) and Back Propagation Algorithm (BPA) for monitoring the combustion conditions of a coal fired boiler so as to control the air/fuel ratio. For this two dimensional flame images are required which was captured with CCD camera whose features of the images, average intensity, area, brightness and orientation etc., of the flame are extracted after pre-processing the images. The FLD is applied to reduce the n-dimensional feature size to 2 dimensional feature size for faster learning of the RBF. Also three classes of images corresponding to different burning conditions of the flames have been extracted from a continuous video processing. In this the corresponding temperatures, the Carbon monoxide (CO) emissions and other flue gases have been obtained through measurement. Further the training and testing of Parallel architecture of Radial Basis Function and Back Propagation Algorithm (PRBFBPA) with the data collected have been done and the performance of the algorithms is presented.

Sinusoidal PWM Signal Generation Using TMS320C6711 DSP for Power Control in Mobile Phones

Pulse Width Modulation is a method of controlling the amount of power to a load without having to dissipate any power in the load driver. PWM signals are widely used in telecommunications, power control systems, voltage regulation and in audio signal processing. This paper deals with the optimized power control in mobile applications. PWM power control systems became reality with the advent of modern semiconductor switches like MOSFETs and Insulated Gate bipolar transistor (IGBT). PWM signals can be easily generated using microcontrollers rather than Digital signal processors (DSP), but when the sensor data from light intensity sensors are processed in real time, then microcontrollers can no longer be used because of less accuracy and speed and this is where DSP comes into play. Programming a DSP to generate PWM signal in accordance with the sensor data is not an easy task since the interfacing codes are not as simple as for microcontrollers. Hence the simulation of the PWM signal has been done to study the efficiency of the C code. This work is a part of a project to develop DSP-FPGA based BLDC motor control.

Monitoring Power Station Boilers Using ANN and Image Processing

This project deals with the monitoring the combustion quality of the power station boilers using Artificial Intelligence for improvement in the combustion quality in the power station boiler. The colour of the flame indicates whether the combustion taking place is complete, partial or incomplete. When complete combustion takes place the flue gases released are within the permissible limits otherwise its level is high which is out of limit. By analyzing the flame color which is captured using infrared camera and displayed on CCTV the quality of combustion is estimated. If combustion is partial or incomplete the flue gases released will create air pollution. So this work includes enhancement in the quality of combustion, saving of energy as well as check on the pollution level. The features are extracted from the flame images such as average intensity, area, brightness and orientation are obtained after preprocessing. Three classes of images corresponding to different burning conditions are taken from continuous video. Further training, testing and validation with the data collected have been carried out and performance of the various intelligent algorithms is presented.

Capacitive Micromachined Ultrasonic Transducer Based Gas Sensor Modeling and Simulation

Micro Electro Mechanical Systems (MEMS) based Ultrasonic Transducers presents several advantages for some applications such as ease of array fabrication, unique thermal manipulation capabilities. Micromachining allows us to miniaturize device dimensions and produce capacitive transducers whose performance is comparable with their piezoelectric counterpart. Computer simulation has been widely used for MEMS based system. The main advantage of computer simulation is to provide design optimization by varying geometry, layer dimension and materials of the device without actual fabrication. This systematic approach can save time and cost of device fabrication and experimentation. In this work, a model of Capacitive Micromachined Ultrasonic Transducer (CMUT) is simulated in COVENTORWARE software. The solver is used to analyze the electrical current flow, voltage and heat and stress distribution in the device. The result is used to predict the temperature and stress as a function of the applied voltage across heating layer. The displacement results are used in the mechanical analysis to predict the mechanical behaviour of the CMUT. Here two different types of dielectric materials Si3N4 and Zr02 are used. The optimization is performed mainly based on resonant frequency and collapse voltage. Then we use this model as a gas detector (Sensor) to detect gas like Methane.

Preperation and Characterization Study of Phase Change Materials for Thermal Energy Storage Applications

Thermal Energy Storage using phase change materials (PCM) has become an interesting area of energy research because of its high energy storage density, isothermal nature of storage process and small volume changes. In the present work paraffin wax (PW) and Palmitic acids(PA) are chosen as phase change materials and mixed in different proportions(40-60% PW-PA, 50-50% PW-PA and 60-40% PW-PA) to prepare eutectic PCMs. And also paraffin is combined with Copper oxide nano powder to prepare composite PCM. Differential Scanning Calorimetric (DSC) Tests have been conducted to find the latent heat capacity of the above combination of PCMs. The results showed that 40-60%PW-PA eutectic mixture is effective in increasing the latent heat of fusion compared to the other combinations.

Performance Investigation of an Eco-Friendly Refrigerant Mixture as an Alternative to R290/R600a

R134a is the most widely used refrigerant in domestic refrigerators. It must be phased out soon according to Kyoto protocol due to its high global warming potential (GWP) of 1300. It has been proposed that by previous experimental investigations, R290/R600a is the best alternate ozone friendly refrigerant mixture for R134a. But due to its high flammability this mixture is not completely substituted as an alternate working fluid in our country. In the present work, performance investigation has been made with eco-friendly refrigerant mixture (composed of R123 and R290 in the ratio of 70:30 by weight) in a refrigerator. This mixture has a very low ozone depletion potential (ODP) and has zero GWP value. Also this mixture has low flammability index when compared with R290/R600a. Continuous running tests were performed under different ambient temperatures (23°C, 28°C, 32°C and 36°C).The ON OFF and DOOR OPEN test results showed that ON TIME percentage of the compressor for the mixture (HCFC123/HC290) is less than that for HCM (R290/R600a). Also the power consumed by mixture (HCFC123/HC290) is lesser by 15% than that of R290/R600a and due to its low flammability property it can be a valuable replacement for the R290/R600a refrigerant mixture.

Chip Morphology Investigation among Dry, Wet and Gas Cooled Machining of Super Duplex Stainless Steel

In this paper, a detailed comparison between dry, wet and gas-cooled turning has been presented based on experimental study. Machining of super duplex stainless steel is considered. Cutting tool considered in this paper is uncoated carbide tool. It was observed that gas cooled machining provides a better machining performance while compared with the dry and the wet machining. Gas cooled machining is particularly needed in case of high speed machining and hard turning. In this study we investigated the chip morphology for various condition of machining and concludes that gas cooled machining is suitable for machining at higher production rate..

Automation of combustion monitoring in boilers using discriminant radial basis network

This research work aims at monitoring and control of the combustion quality in a power station coal fired boiler using a combination of Fishers linear discriminant FLD analysis and radial basis network RBN. The flame video is acquired with CCD camera. The features of the flame images like average intensity, area of the flame, brightness of the flame, orientation of the flame, etc. are extracted from the preprocessed images. The FLD is applied to reduce the n-dimensional feature size to two-dimensional feature size for faster learning by the RBN. The results of the proposed technique are compared with the conventional Euclidean distance classifier EDC, which is also used to find the distance between the three groups of images. Three groups of images corresponding to different combustion conditions of the flames have been extracted from a continuous video. The corresponding temperatures and the carbon monoxide CO in the flue gas have been obtained through measurements. Training and testing of Fishers linear discriminant radial basis network FLDRBN with the data collected have been done and the performances of the various algorithms are evaluated.

Properties of ferroelectric glycine phosphite single crystals

The optically transparent single crystals of Glycine Phosphite (GPI) doped with metals, rare earths, dyes and amino acid were grown by both solvent evaporation and temperature lowering techniques. Concentration of dopants was chosen depending on the category of dopants and quality of crystallization during the growth process. Incorporation of dopants was identified using ESR, AAS, ICP, XRF and UV-Visible spectral analyses. Single crystal XRD was carried out to determine the lattice parameters and to analyze the structural morphology of GPI with dopants. Crystalline perfection of crystals was determined by HRXRD analysis by means of FWHM values. Ferroelectric transition temperature was identified by dielectric and DSC measurements. Piezoelectric charge coefficient d33 and Hysteresis (P-E) loop was measured for crystals. Microhardness measurement was carried out for understanding the mechanical stability of the crystals, the mechanical properties such as elastic stiffness constant ‘C11’, yield strength ‘σy’ were calculated from hardness value. Meyer’s index number was in the range of 1.6 to 2 for all the crystals. This indicates that the grown crystals are relatively soft materials.The optically transparent single crystals of Glycine Phosphite (GPI) doped with metals, rare earths, dyes and amino acid were grown by both solvent evaporation and temperature lowering techniques. Concentration of dopants was chosen depending on the category of dopants and quality of crystallization during the growth process. Incorporation of dopants was identified using ESR, AAS, ICP, XRF and UV-Visible spectral analyses. Single crystal XRD was carried out to determine the lattice parameters and to analyze the structural morphology of GPI with dopants. Crystalline perfection of crystals was determined by HRXRD analysis by means of FWHM values. Ferroelectric transition temperature was identified by dielectric and DSC measurements. Piezoelectric charge coefficient d33 and Hysteresis (P-E) loop was measured for crystals. Microhardness measurement was carried out for understanding the mechanical stability of the crystals, the mechanical properties such as elastic stiffness constant ‘C11’, yield strength ‘σy’...