Forgotten index of duplication and double duplication of graphs by means of degree sequences

R. Kalpana,L. Shobana,Ismail Naci Cangul 장전수학회 2023 Proceedings of the Jangjeon mathematical society Vol.26 No.1

Forgotten index of duplication and double duplication of graphs by means of degree sequences

Direct Single-stage Power Converter with Power Factor Improvement for Switched Mode Power Supply

Kalpana, R.,Singh, Bhim,Bhuvaneswari, G. The Korean Institute of Electrical Engineers 2010 Journal of Electrical Engineering & Technology Vol.5 No.3

This paper presents a direct single-stage power converter using single-phase isolated full-bridge converter modules, with inherent power factor correction (PFC) for a 12 kW switched mode power supply (SMPS). The advantages of the proposed converter are its simple control strategy, reduction in number of conversion stage, low input line current harmonics, and improvement in power factor. Analysis of the single-stage converter is carried out in continuous conduction mode of operation. Steady-state analysis of the proposed converter is conducted to obtain converter parameters. A systematic design procedure is also presented for a 12k W converter with a design example. The effect of load variation on SMPS is also studied in order to demonstrate the effectiveness of the proposed converter for the complete range of load conditions. A set of power quality indices on input ac mains for an SMPS fed from a single-stage converter is also presented for easy comparison of their performance.

Direct Single-stage Power Converter with Power Factor Improvement for Switched Mode Power Supply

R. Kalpana,Bhim Singh,G. Bhuvaneswari 대한전기학회 2010 Journal of Electrical Engineering & Technology Vol.5 No.3

This paper presents a direct single-stage power converter using single-phase isolated fullbridge converter modules, with inherent power factor correction (PFC) for a 12 kW switched mode power supply (SMPS). The advantages of the proposed converter are its simple control strategy, reduction in number of conversion stage, low input line current harmonics, and improvement in power factor. Analysis of the single-stage converter is carried out in continuous conduction mode of operation. Steady-state analysis of the proposed converter is conducted to obtain converter parameters. A systematic design procedure is also presented for a 12k W converter with a design example. The effect of load variation on SMPS is also studied in order to demonstrate the effectiveness of the proposed converter for the complete range of load conditions. A set of power quality indices on input ac mains for an SMPS fed from a single-stage converter is also presented for easy comparison of their performance.

Structural, dielectric, electrical and magnetic properties of chemicothermally synthesized material: BiCaFeCeO6

Parida Kalpana,Choudhary R.N.P. 한국물리학회 2021 Current Applied Physics Vol.21 No.-

In this communication, detailed studies of structural, micro-structural, dielectric, electrical (impedance, modulus and conductivity) and magneto-electric characteristics of a chemico-thermally synthesized sample of a double perovskite bismuth calcium iron cerate (BiCaFeCeO6) have been reported. Preliminary structural analysis of room temperature X-ray diffraction data shows orthorhombic structure of the material. The homogeneous distribution of the grains of different dimensions (shape, size, etc) with a small number of voids observed in the scanning electron micrograph suggests the formation of high-density sample. Detailed analysis of dielectric and impedance experimental data, collected at different frequency and temperatures, have provided many important characteristics of the material, such as (a) grains, grain boundaries, and electrode dependent capacitive and impedance parameters, (b) co-relation between the structure, micro-structure and physical properties and (c) the relaxation characteristics of the tested samples. The nature of frequency dependence of AC conductivity of the material obeys the Jonscher’s universal power law. The temperature dependence of conductivity provides the conduction mechanism in the material. Detailed studies of field dependence of electric polarization, magnetization and magneto-electric coefficient at room temperature exhibit the multiferroic characteristics of the material.

Multiscale Modeling of Swelling Clays: A Computational and Experimental Approach

Dinesh R. Katti,Mohamed I. Matar,Kalpana S. Katti,Priyanthi M. Amarasinghe 대한토목학회 2009 KSCE Journal of Civil Engineering Vol.13 No.4

Expansive clays such as montmorillonite cause severe distress to infrastructure due to swelling. The swelling of montmorillonite clay is also the basis for its use in many commercial applications such as drilling muds in petroleum engineering, as landfill liners in environmental engineering and in making polymer clay nanocomposites. The focus of this work is to carry out a systematic experimental and numerical study to understand and model behavior of Na-montmorillonite at molecular and particulate level to find mechanism of swelling in the Na-montmorillonite interlayer. Experimental results show breakdown of particles with an increase in swelling of the clay. This phenomenon was numerically studied by developing a modified Discrete Element Method (DEM) model that incorporates the latest developments in both clay and computer science, and can simulate particle subdivision. DEM results show the role of particle subdivision on swelling and swelling pressure. In understanding the true mechanism of swelling, it is essential to incorporate the interactions between clay molecular structure and the interlayer water molecules. For bridging the length scales, we have also evaluated the stress deformation response of the clay molecular structure using Molecular Dynamic (MD) simulations. Simulation results show that the deformation in the clay molecular structure due to external stress is mostly due to deformation of the water molecules in the clay interlayer. A new experimental technique which enables us to capture the molecular changes in the clay molecular structure upon hydration is also developed. This work provides a foundation for multiscale modeling of swelling clays. Expansive clays such as montmorillonite cause severe distress to infrastructure due to swelling. The swelling of montmorillonite clay is also the basis for its use in many commercial applications such as drilling muds in petroleum engineering, as landfill liners in environmental engineering and in making polymer clay nanocomposites. The focus of this work is to carry out a systematic experimental and numerical study to understand and model behavior of Na-montmorillonite at molecular and particulate level to find mechanism of swelling in the Na-montmorillonite interlayer. Experimental results show breakdown of particles with an increase in swelling of the clay. This phenomenon was numerically studied by developing a modified Discrete Element Method (DEM) model that incorporates the latest developments in both clay and computer science, and can simulate particle subdivision. DEM results show the role of particle subdivision on swelling and swelling pressure. In understanding the true mechanism of swelling, it is essential to incorporate the interactions between clay molecular structure and the interlayer water molecules. For bridging the length scales, we have also evaluated the stress deformation response of the clay molecular structure using Molecular Dynamic (MD) simulations. Simulation results show that the deformation in the clay molecular structure due to external stress is mostly due to deformation of the water molecules in the clay interlayer. A new experimental technique which enables us to capture the molecular changes in the clay molecular structure upon hydration is also developed. This work provides a foundation for multiscale modeling of swelling clays.

Improving the performance of location based spatial textual query processing using distributed strip index

M. Priya,R. Kalpana 대한공간정보학회 2019 Spatial Information Research Vol.27 No.5

Location Based Services are information retrieval services that offer accurate information required by the end user. These services are the query based services accessed mainly through mobile devices and have number of uses in social networking for providing entertainment, business and healthcare information. In health care system, if a person wants to get immediate medical help at any place, he needs to access a medical database with the help of location-based query. Sometimes, location-based query can associate with the text information, such as the user wants to find the nearest hospital with the facility of pharmacy or ambulance. This type of query has to resolve both location and textual information. This paper proposes a new distributed index structure to resolve location-based query, and introduces a new probabilistic mechanism to correct the typographical errors when retrieving the documents. The experimental results show that the distributed strip index structure produces better performance than the existing distributed R tree structure.

Impedance spectroscopy study of zinc oxide incorporated iron borate glass-ceramic

Ramteke Rajat,Kumari Kalpana,Bhattacharya Soumalya,Sharma Sanjeev Kumar,Rahman M.R. 한국물리학회 2021 Current Applied Physics Vol.22 No.-

Here, the effects of zinc oxide (ZnO) on impedance and dielectric properties of the ZnO incorporated iron borate (Fe3BO6) glass-ceramics were studied using impedance spectroscopy in a wide range of frequency (1 Hz – 1 MHz) and temperature (25 ◦C–250 ◦C). With ZnO addition, the ε′ and tanδ values were reduced significantly, the strength of the relaxation process also decreased, along with a decrease in conductivity. Activation energies associated with modulus and conductivity plots suggest that similar type of charge carriers was responsible for the relaxation and conduction processes. The analysis of both complex impedance and conductivity show the negative temperature coefficient of resistance (NTCR) behavior of the samples. The thermistor constant B-values of 5ZnO and 10ZnO were found to be 7223 and 7088 respectively. The study of the NTCR properties suggests a potential candidate for thermistor applications.

Biomediated Silver Nanoparticles for the Highly Selective Copper(II) Ion Sensor Applications

Kirubaharan, C. Joseph,Kalpana, D.,Lee, Yang Soo,Kim, A. R.,Yoo, Don Jin,Nahm, Kee Suk,Kumar, G. Gnana American Chemical Society 2012 INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH - Vol.51 No.21

<P>Nanoparticles synthesis is an evergreen research field of 21st century in which the connotation of the biomediated experimental process is highly imperative. Biomediated silver nanoparticles were synthesized with the aid of an eco-friendly biomaterial, namely, aqueous <I>Azadirachta indica</I> extract. The effect of pH and temperature on the formation of silver nanoparticles was analyzed. Formation of the silver nanoparticles was verified by surface plasmon spectra using a UV–vis spectrophotometer. Morphology and crystalline structure of the prepared silver nanoparticles were characterized by TEM and XRD techniques, respectively. Furthermore, the biomediated silver nanoparticles without any surface modification were used for the heavy metal ion sensors in aqueous media. The prepared silver nanoparticles were successful in detecting even the minimal amount of heavy metal copper(II) ion and exhibited excellent specific metal ion selectivity.</P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ie3003232'>ACS Electronic Supporting Info</A></P>

Three-phase Three-level Boost-type Front-end PFC Rectifier for Improving Power Quality at Input AC Mains of Telecom Loads

Saravana Prakash P.,R. Kalpana,Bhim Singh 전력전자학회 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.6

A three-phase, three-switch, and three-level boost-type PWM rectifier (Vienna rectifier) is proposed as an active front-end power factor correction (PFC) rectifier for telecom loads. The proposed active front-end PFC rectifier system is modeled by the switching cycle average model. The relation between duty ratios and DC link capacitor voltages is derived in terms of the system input currents. Furthermore, the feasible switching states are identified and applied to the proposed system to reduce the switching stress and DC ripples. A detailed equivalent circuit analysis of the proposed front-end PFC rectifier is conducted, and its performance is verified through simulations in MATLAB. Simulation results are verified using an experimental setup of an active front-end PFC rectifier that was developed in the laboratory. Simulation and experimental results demonstrate the improved power quality parameters that are in accordance with the IEEE and IEC standards.

Evaluation and Identification of Promising Bivoltine Hybrids of Silkworm , Bombyx mori L. , for Tropics

(P. Sudhakara Rao),(Ravindra Singh),(G. V. Kalpana),(V. Nishitha Naik),(H. K. Basavaraja),(G. N. Rama Swamy),(R. K. Datta) 한국잠사학회 2001 International Journal of Industrial Entomology Vol.3 No.1