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Gulbarga, India

Gulbarga University is a public university located in Gulbarga, Karnataka, India. Its jurisdiction extends to the four districts of Gulbarga District, Bidar District, Raichur District, and Yadgir District of Karnataka. It has more than 37 teaching departments and 4 research centres and also acts as an affiliating university. Wikipedia.

Gayakwad R.,Gulbarga University
Acta Polytechnica Hungarica | Year: 2010

For any fuzzy logic application the first and foremost task is to select the optimum number and shape of membership functions such as bell shape, singleton, triangular, etc. for fuzzification; then it is equally essential to select the appropriate defuzzification method, such as COG, COM, MOM, etc. The sampling rate to execute the given command is another important parameter. If these three parameters are optimally selected then the output response of motion controller will have a shorter rise time, less settling time, minimized overshoots/undershoots and negligible steady state error. Hence, the systematic study on selection of number and shape of membership function, selection of defuzzification methods and sampling time for speed control of PMDC micro motor is studied experimentally by applying LabVIEW software. The experimental results reveal that 7 numbers of triangular membership functions, COG defuzzification method and 1 millisecond (msec) sampling rate for labVIEW program execution are the optimum parameters for motion control. Source

Malashetty M.S.,Gulbarga University | Swamy M.S.,Government College
Physics of Fluids | Year: 2011

The combined effect of gravity modulation and rotation on the onset of thermal convection in a horizontal fluid layer and a fluid-saturated porous layer is studied analytically using linear stability theory. The regular perturbation method based on small amplitude of modulation is employed to compute the critical value of Rayleigh number and wavenumber. We considered in the present paper only synchronous mode. The correction critical Rayleigh number is calculated as a function of Taylor number, Prandtl number, Darcy number, frequency of the modulation, normalized porosity, and viscosity ratio. It is shown that in general the gravity modulation produces a stabilizing effect in case of viscous fluid layer and both destabilizing and stabilizing effects in case of Brinkman porous layer while it produces a destabilizing effect in case of Darcy porous layer. The low frequency gravity modulation is found to have a significant effect on the stability of the system. It is shown that the onset of convection can be advanced or delayed by proper tuning of various governing parameters. The results of Darcy limit and viscous flow limit are derived as the degenerate cases of Brinkman model. © 2011 American Institute of Physics. Source

Umavathi J.C.,Gulbarga University
Transport in Porous Media | Year: 2013

The effect of time-periodic temperature modulation at the onset of convection in a Boussinesq porous medium saturated by a nanofluid is studied analytically. The model used for the nanofluid incorporates the effects of Brownian motion. Three types of boundary temperature modulations are considered namely, symmetric, asymmetric, and only the lower wall temperature is modulated while the upper wall is held at constant temperature. The perturbation method is applied for computing the critical Rayleigh and wave numbers for small amplitude temperature modulation. The shift in the critical Rayleigh number is calculated as a function of frequency of modulation, concentration Rayleigh number, porosity, Lewis number, and thermal capacity ratio. It has been shown that it is possible to advance or delay the onset of convection by time-periodic modulation of the wall temperature. The nanofluid is found to have more stabilizing effect when compared to regular fluid. Low frequency is destabilizing, while high frequency is always stabilizing for symmetric modulation. Asymmetric modulation and only lower wall temperature modulation is stabilizing for all frequencies when concentration Rayleigh number is greater than one. © 2013 Springer Science+Business Media Dordrecht. Source

Umavathi J.C.,Gulbarga University
Transport in Porous Media | Year: 2013

Numerical investigation of steady natural convection flow through a fluid-saturated porous medium in a vertical rectangular duct is investigated. The Darcy-Forchheimer-Brinkman model is used to represent the fluid transport within the porous medium. One of the vertical walls of the duct is cooled to a constant temperature, while the other wall is heated to constant but different temperature. The other two sides of the duct are insulated. The finite difference method of second-order accuracy is used to solve the non-dimensional governing equations. The results are presented graphically to show the effects of the Darcy number, inertial parameter, Grashof number, Brinkman number, aspect ratio, and viscosity ratio. It is found that an increase in the Darcy number and inertial parameter reduces the flow intensity whereas an increase in the Grashof number, Brinkman number, aspect ratio, and viscosity ratio increases the flow intensity. © 2012 Springer Science+Business Media Dordrecht. Source

Uma Reddy B.,Gulbarga University
E-Journal of Chemistry | Year: 2010

The present study was aimed to investigate the antibacterial activity of some common locally available plants, in order to estimate the biological potential of these herbs. The alcoholic extract of Tagetes erecta L (Asteraceae), Argemone mexicana L (Papavaraceae), Datura stramonium L. (Solanaceae) and Tylophora indica (Burm.f.) Merr. (Asclepiadaceae) were evaluated for antibacterial activity using broth dilution bioassay method. It is clear from the results that, the extracts of these plants acts as a good source of antibiotics against various bacterial pathogens tested and exhibited broad spectrum of antibacterial activity. These plant extracts were shown to be moderate to maximum inhibitory effect against different bacterial forms such as Salmonella typhii, Proteus vulgaris, Pseudomonas aeruginosa and Escherichia coli, where as, mild to moderate activity against Klebsiella pneumoniae and Staphylococcus aureus. The results of these studies revealed most valuable information and also support the continued sustainable use of these plants in traditional systems of medicine. Source

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