Kanak Chandra Sarma

Newly developed Fe3O4–Cr2O3 magnetic nanocomposite for photocatalytic decomposition of 4-chlorophenol in water

Chlorophenols, typically 4-chlorophenols are highly toxic and non-biodegradable organic contaminants which pose serious threat to the environment, particularly when released into aqueous medium. The removal of these pollutants by efficient method has received worldwide concern in recent past. A new Fe3O4-Cr2O3 magnetic nanocomposite was synthesized by wet chemical method under ultrasonic irradiation. Microstructure and morphology of the nanocomposite were characterized by powder X-ray diffraction (XRD), Fourier transform infrared (FT-IR), and a transmission electron microscope (TEM). Magnetic and optical properties were studied by a vibrating sample magnetometer (VSM) and an ultraviolet-visible (UV-Vis) spectrophotometer respectively. The magnetic nanocomposite (MNC) was used as photocatalyst for effective decomposition of 4-chlorophenol in water under ultraviolet (UV) irradiation.

Approaches and Issues in Offline Signature Verification System

Offline signature verification is one of most challenging area of pattern recognition. In this paper, we have presented a survey of various approaches and issues related to offline signature verification systems. We have presented some of the research works including comprehensive references as an aid for researchers working in the field.

A comparative study on client server technology and web technology in design and implementation of an embedded system used for monitoring and controlling of physical parameters

System developed for the stated study is a microcontroller based embedded system for monitoring and controlling of parameters like temperature and humidity. It can be implemented using simple client server technology as well as web technology. Users belong to the organizational domain can use their own Intranet for monitoring and controlling of parameters designed on simple client server technology whereas users beyond the scope of Intranet can use Internet interface designed using web technology. Both the technologies are having its own advantages as well as disadvantages. This paper explores the technological implications of the system using client server as well as web technology. Embedded hardware circuit is fabricated in to two separate digital circuits connecting two COM ports of Embedded server. First circuit will monitor temperature and humidity and display same in LCD. Application program executed in computer reads COM port and display the same in monitor and store in database. Second digital circuit will provide necessary hardware control of devices for controlling of temperature and humidity automatically. It is implemented through relay based on the user entered set value of temperature and humidity which is stored in database of computer. Developed system enable its both Intranet as well as or Internet users for monitoring and setting new values of temperature and humidity through the respective front end.

Design and Development of Low Cost Multi-Channel USB Data Acquisition System for the Measurement of Physical Parameters

ABSTRACT This paper describes the design and development of low cost USB Data Acquisition System (DAS) for the measurement of physical parameters. Physical parameters such as temperature, humidity, light intensity etc., which are generally slowly varying signals are sensed by respective sensors or integrated sensors and converted into voltages. The DAS is designed using PIC18F4550 microcontroller, communicating with Personal Computer (PC) through USB (Universal Serial Bus). The designed DAS has been tested with the application program developed in Visual Basic, which allows online monitoring in graphical as well as numerical display. General Terms Data Acquisition System (DAS), Universal Serial Bus (USB), Microcontroller. Keywords Data Acquisition System (DAS), temperature, humidity, online monitoring. 1. INTRODUCTION As the computer technology advances, the performance and the availability of the PCs and Laptop become reliable, common and also the prices are falling drastically. Thus, the design and development of the low cost PC based DAS using microcontrollers for use in various fields has been a challenging task. Research is going on in various fields for the design and development of low cost real time DAS [1-5]. Physical parameters such as temperature, pressure, humidity, light intensity etc., are generally slowly varying signals. They can be sensed by respective sensor or transducer giving changes in electrical parameters. In the laboratories or industrial environment, it is very much essential to monitor and/or control such physical parameters. Manual observation and recording of such parameters for continuously for a long time is almost impossible and it cannot fulfill the current requirements in terms of the accuracy and time duration. The efficient solution of this problem is to develope data logger or DAS [6-7]. The present work is to explore the design and development of the low cost multi channel USB DAS using PIC18F4550 microcontroller for continuous monitoring and storing of the physical parameters such as temperature, humidity, etc. Most of the researcher develop application program to customize the readymade data acquisition (DAQ) cards for their specific application. The unique feature of our designed DAS is that, it is designed and developed with commonly available components in the market at low cost; firmware and application program are also developed and are user friendly.

Design of a USB based Multichannel, Low Cost Data Acquisition System using PIC Microcontroller

This paper describes the design and development of a low cost Data Acquisition System (DAS) using PIC18LF4553 microcontroller for real time data acquisition. The designed DAS has 4 analog input channels having 12-bit resolution and was interfaced through the USB port of the PC. The interface to the PC is basically a USB based virtual serial port emulation using FT232R, a USB to serial UART interfacing IC. The PIC microcontroller firmware has been written in C language and compiled using MikroC compiler for PIC and downloaded to the microcontroller by using USBurn programmer for PIC. A PC application program has been also developed using MATLAB, which allows displaying the waveform of the signal(s) in real time and storing the data into the hard disk of the computer for future use and analysis.

Exchange bias effect in CoFe2O4-Cr2O3 nanocomposite embedded in SiO2 matrix

A nanogranular system composed of CoFe2O4-Cr2O3 core-shell nanoparticles (embedded in SiO2 matrix) having average particle size of 35 ± 5 nm was prepared by chemical synthesis. Structural characterizations by x-ray diffraction, Transmission Electron Microscope (TEM) show highly crystalline phase of these nanocomposites. High resolution TEM images show distorted and modified grain boundary region. CoFe2O4-Cr2O3 nanocomposites show excellent positive exchange bias effect after field cooling at 100 Oe of applied field. Both the exchange bias field and vertical shift in magnetization loop has been observed in this system below 300 K after field cooling. There is a positive loop shift of about 5 kOe along the field axis at 20 K in this system while the vertical shift is nearly 100% owing to the strong exchange bias effect. The exchange bias effect has been explained in terms of the different magnetic exchange interactions and modified grain boundary effect of CoFe2O4-Cr2O3 nanocomposites. The role of spin glas...

MICROSTRUCTURAL CHANGES UPON ANNEALING AND IT'S EFFECT ON MAGNETIC AND MECHANICAL PROPERTIES OF NANOSIZED COBALT–FERRITE

Nanocrystalline cobalt–ferrite particles of size 20–30 nm have been prepared by a reverse coprecipitation technique under the assistance of ultrasonic irradiation and heat-treatment at different temperatures (from 473 K to 1073 K). Both X-ray diffraction and transmission electron microscope analysis confirms the reduction of strain present in the material with annealing temperature. Enhancement of coercivity and magnetization value has been observed without increase in the particle size for whole range of annealing temperature. Temperature dependent magnetization loop shows considerable magnetic hardening at low temperature. The observed enhancement of the coercivity value has been attributed to the increase in magneto-crystalline anisotropy, surface effects and exchange anisotropy. The mechanical properties of the pure cobalt–ferrite samples and cobalt–ferrite reinforced alumina samples were also examined. The Vickers microhardness and the compressive properties obtained from the stress–strain relation showed higher value with annealing temperatures and higher nanoparticle content.

SYNTHESIS AND CHARACTERIZATION OF BIFUNCTIONAL CoFe2O4–ZnS NANOCOMPOSITE

The synthesis of composite magnetic nanomaterials has received increasing attention due to their electronic, magnetic, catalytic, and chemical or biological sensing properties. We have prepared cobalt ferrite–zinc sulfide nanocomposites by a chemical route. The synthesized nanocomposites were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), vibrating sample magnetometer (VSM), and photoluminescence spectrometer (PL). The fluorescent magnetic nanoparticles (FMNPs) had a typical diameter of 30±5 nm and saturation magnetization of 5.8 emu g-1 at room temperature. So, these FMNPs may be potentially applied in different fields such as optoelectronic devices, biolabeling, imaging, drug targeting, bioseparation, magnetic fluid hyperthermia, etc.

Optical and Structural Studies of Chemically Synthesized ZnO Nanocrystals

ZnO nanocrystals were synthesized by adopting quenching method with Poly-vinyl alcohol as the matrix. X-ray diffraction, UV-vis spectroscopy, Photoluminescence, scanning electron microscopy, energy dispersive x-ray spectroscopy and transmission electron microscopy has been used to study the prepared samples. The size of the nanocrystals is in the range of 6.9 nm to 12.5 nm. We have successfully varied the size of the nanocrystals by varying the weight ratio of poly-vinyl alcohol and ZnO. The conductivity of the samples has been tested in atmospheric pressure as well as in vacuum.

Offline Signature Verification Using Radial Basis Function with Selected Feature Sets

This paper presents evaluation results of support vector machine (SVM) classifiers with radial basis function (RBF) kernel in offline signature verification. We have used two data sets of offline signatures and extracted 15 (fifteen) features from each signature sample of the data sets. The best feature subsets of the data sets were selected using filter and wrapper methods. For both the data sets, SVM classifiers with RBF kernel were designed with every selected feature sets individually. Classifiers were optimized, and their performances were evaluated using 10-fold cross-validation. Another classifier was designed using both the data sets combined to test the generalizability of the classifier across two different signatures.