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Search Results: 1 - 10 of 146490 matches for " Krishna B. Chavaraddi "
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Kelvin-Helmholtz Instability in a Fluid Layer Bounded Above by a Porous Layer and Below by a Rigid Surface in Presence of Magnetic Field  [PDF]
Krishna B. Chavaraddi, Nagaraj N. Katagi, Vishwanath B. Awati
Applied Mathematics (AM) , 2012, DOI: 10.4236/am.2012.36086
Abstract: We study the stability of an interface between two fluids of different densities flowing parallel to each other in the presence of a transverse magnetic field. A simple theory based on fully developed flow approximations is used to de-rive the dispersion relation for the growth rate of KHI. We replace the effect of boundary layer with Beavers and Joseph slip condition. The dispersion relation is derived using suitable boundary and surface conditions and results are discussed graphically. The magnetic field is found to be stabilizing and the influence of the various parameters of the problem on the interface stability is thoroughly analyzed. These are favorable to control the surface instabilities in many practical applications discussed in this paper.
Semi Numerical Solution for a Boundary Value Problem  [PDF]
N.P. Pai, N. N. Katagi, Krishna B. Chavaraddi
American Journal of Computational Mathematics (AJCM) , 2013, DOI: 10.4236/ajcm.2013.31006
Abstract:

The flow of viscous incompressible fluid through a tube is considered. The similarity transformation is used to reduce the governing equations into nonlinear ordinary differential equation. The solution procedure includes application of long series analysis with polynomial coefficients. The series representing physical parameters (\"\" ) reveal qualitative features which are comparable to pure numerical results. The analysis enables in extending region of validity. A complete description of the solutions is presented.

Effect of Magnetic Field on Kelvin-Helmholtz Instability in a Couple-Stress Fluid Layer Bounded Above by a Porous Layer and Below by a Rigid Surface  [PDF]
Krishna B. Chavaraddi, Vishwanath B. Awati, Nagaraj N. Katagi, Priya M. Gouder
Applied Mathematics (AM) , 2016, DOI: 10.4236/am.2016.716164
Abstract: Kelvin-Helmholtz instability (KHI) appears in stratified two-fluid flow at surface. When the relative velocity is higher than the critical relative velocity, the growth of waves occurs. It is found that magnetic field has a stabilization effect whereas the buoyancy force has a destabilization effect on the KHI in the presence of sharp inter-face. The RT instability increases with wave number and flow shear, and acts much like a KHI when destabilizing effect of sheared flow dominates. It is shown that both of ablation velocity and magnetic field have stabilization effect on RT instability in the presence of continued interface. In this paper, we study the effect of magnetic field on Kelvin-Helmholtz instability (KHI) in a Couple-stress fluid layer above by a porous layer and below by a rigid surface. A simple theory based on fully developed flow approximations is used to derive the dispersion relation for the growth rate of KHI. We replace the effect of boundary layer with Beavers and Joseph slip condition at the rigid surface. The dispersion relation is derived using suitable boundary and surface conditions and results are discussed graphically. The stabilization effect of magnetic field takes place for whole waveband and becomes more significant for the short wavelength. The growth rate decreases as the density scale length increases. The stabilization effect of magnetic field is more significant for the short density scale length.
Study of Surface Instability of Kelvin-Helmholtz Type in a Fluid Layer Bounded above by a Porous Layer and below by a Rigid Surface  [PDF]
Nanjundappa Rudraiah, Krishna Basappa Chavaraddi, Inapura Siddagangaiah Shivakumara, Bangalore Mahadevaiah Shankar
World Journal of Mechanics (WJM) , 2011, DOI: 10.4236/wjm.2011.16033
Abstract: The surface instability of Kelvin-Helmholtz type bounded above by a porous layer and below by a rigid surface is investigated using linear stability analysis. Here we adopt the theory based on electrohydrodynamic as well as Stokes and lubrication approximations. We replace the effect of boundary layer with Beavers and Joseph slip condition. Here we have studied the combined effect of electric and magnetic fields on Kelvin-Helmholtz instability (KHI) in a fluid layer bounded above by a porous layer and below by a rigid surface. The dispersion relation is obtained using suitable boundary and surface conditions and results are depicted graphically. Also the ratio Gm is numerically computed for different values of We and M given in the Table 1. From this it is clear that the combined effect of electric and magnetic fields with porous layer are more effective than the effect of compressibility in reducing the growth rate of RTI. Also, these results shows that with a proper choice of magnetic field it is possible to control the growth rate of Electrohydrody-namic KHI (EKHI) and hence can be restored the symmetry of IFE target.
Design of Compensator of Approximation of Large Time Delay Systems via Reduced Order Model.
T. Narasimhulu,B. Krishna
International Journal of Engineering Sciences & Research Technology , 2013,
Abstract: The present paper deals with a approximating method for large time – delays of multi-input multi-output (MIMO) dynamical systems. Time delay terms of the state space equations are described by delay matrix in the complex domain. A mixed model reduction method of matrix Pade-type-Routh model for the multivariable linear systems was presented. Matrix Pade-type Routh model approximation can largely reduce the instability and the overshoot, so the fast response property is improved. Simulation results of the proposed method are presented to illustrate the correctness and effectively
Nepal: From absolute monarchy to
Krishna B.Bhattachan
International Journal of Inclusive Democracy , 2005,
Abstract: This paper gives a picture of the forest of inclusive democracy in Nepal, which is in the preliminary process of making. The paper begins with an overview of what went wrong in the past and the present in a multi-caste/ethnic, multi-lingual, multi-religious and multi-cultural country, Nepal, as perceived by excluded groups/communities. It identifies that the main socio-cultural-political fault line in the past and the present, irrespective of political systems, is the ideology, policy and practice of Bahunbad (Brahmanism). The main playing fields of Bahunbad discussed in the paper include caste/ethnicity, language, religion, culture, gender and region. This paper analyzes demands made by different excluded groups/communities, including indigenous nationalities, Dalit, Madhesi Hindus and Muslims, women, mother tongue speakers and non-Hindu religious groups, to create a just, equitable and democratic Nepalese society and also to bring positive peace in Nepal. The paper analyzes in detail mechanisms to include excluded groups/communities with focus on interconnection of federalism, proportional representation, autonomy based on caste/ethnicity, language and region and special measures or affirmative action or positive discrimination—remedial and preferential. Grassroots democracy as practiced by some indigenous nationalities is also discussed. It is attempted to clarify that these mechanisms neither result in nor encourage disintegration of the country and communal violence, as perceived by Bahunbadis. On the contrary, these are indeed desperately needed to avoid any such misfortune in the days to come by maintaining minimal unity in highly diversified society. Also, the means to this end is also discussed with suggestion to trash reformist agenda by advocating for rights-based movement blended with revolutionary or radical transformation through roundtable conference, right to self-determination, public propositions and referendum and constituent assembly to rewrite the constitution and to practice inclusive democracy. This paper concludes with a message that any other model of democracy, except inclusive, in Nepal would continue to breed insurgency based on caste/ethnicity, language, religion and region and the best way to avoid them is inclusive democracy as suggested.
Role of radionuclide scintigraphy in the detection of parathyroid adenoma
Singh N,Krishna B
Indian Journal of Cancer , 2007,
Abstract: Background: Preoperative detection of parathyroid adenoma is a diagnostic challenge. The sonography and computerized tomography (CT) scan demonstrate high sensitivity but low specificity. The advent of radionuclide scanning technique has enhanced the specificity in this context. Aim: We undertook a study to assess the role of radionuclide scanning in suspected cases of parathyroid adenomas. Materials And Methods: Totally 28 cases were incorporated in the study. The suspicion was raised either due to raised PTH levels or recurrent calcinosis. Most of these patients had estimation of calcium done as a routine or specific investigation. The parathyroid scan was performed using either of the two techniques - Dual isotope subtraction or Sestamibi washout technique. We also used the recent approach of fusion imaging (CT + tomographic nuclear images) in selected cases. Results: There were 16 true positive, 10 true negative, 1 false negative and 1 equivocal scan findings. The findings were compared with sonography, CT Scan and PTH values. The true positive yield in our study was 57%, true negative 35% and the overall sensitivity and specificity was found to be 94% and 100% respectively. Conclusion: We conclude that parathyroid scintigraphy is a reliable and sensitive technique in the preoperative detection of parathyroid adenomas and should be the first choice of imaging modality in suspicion of parathyroid adenoma.
Time Series Modeling of River Flow Using Wavelet Neural Networks  [PDF]
B. Krishna, Y. R. Satyaji Rao, P. C. Nayak
Journal of Water Resource and Protection (JWARP) , 2011, DOI: 10.4236/jwarp.2011.31006
Abstract: A new hybrid model which combines wavelets and Artificial Neural Network (ANN) called wavelet neural network (WNN) model was proposed in the current study and applied for time series modeling of river flow. The time series of daily river flow of the Malaprabha River basin (Karnataka state, India) were analyzed by the WNN model. The observed time series are decomposed into sub-series using discrete wavelet transform and then appropriate sub-series is used as inputs to the neural network for forecasting hydrological variables. The hybrid model (WNN) was compared with the standard ANN and AR models. The WNN model was able to provide a good fit with the observed data, especially the peak values during the testing period. The benchmark results from WNN model applications showed that the hybrid model produced better results in estimating the hydrograph properties than the latter models (ANN and AR).
EUS guided fine needle aspiration is useful in diagnostic evaluation of indeterminate proximal biliary strictures  [PDF]
Naveen B. Krishna, Pavan Tummala, Jennifer L. Labundy, Banke Agarwal
Open Journal of Gastroenterology (OJGas) , 2012, DOI: 10.4236/ojgas.2012.22008
Abstract: Background and Aim: Determination of the etiology of proximal biliary strictures (PBS) still remains a challenge. Even though EUS-FNA is potentially useful, its role in diagnostic evaluation of PBS is still not established due to a lack of sufficient data. We sought to determine the performance characteristics of EUS-FNA in patients with obstructive jaundice (ObJ) and PBS. Patients and Methods: This is a retrospective analysis and included patients with ObJ and PBS with non-diagnostic brush cytology, who underwent EUS-FNA in our university based practice from March 2002 to February 2009. We evaluated the final diagnoses in study patients and the performance characteristics of EUS-FNA for identifying malignant PBS. Final diagnosis was based on surgical pathology or clinical follow-up of at least 12 months. Results: The study included 28 patients (17 male, 11 female) with mean age of 62.4 ± 14.9 years. The strictures ranged from 10 - 70 mm in length. CT scan identified a hilar mass in 9 patients. EUS-FNA identified malignancy in 12 patients. 18 patients were finally diagnosed to have a malignant stricture and 10 patients had a benign stricture. There were 6 false negative diagnoses. The accuracy of EUS-FNA for diagnosis of cholangiocarcinoma was 78.6%, with 66.6% sensitivity, 100% specificity, 62.5% NPV and 100% PPV. Conclusions: EUS-FNA can diagnose malignancy in 66.6% of jaundiced patients with PBS and non-diagnostic brush cytology and may have a role in their further diagnostic evaluation.
Spectral Discrimination of Two Pigweeds from Cotton with Different Leaf Colors  [PDF]
Reginald S. Fletcher, Krishna N. Reddy, Rickie B. Turley
American Journal of Plant Sciences (AJPS) , 2016, DOI: 10.4236/ajps.2016.715190
Abstract: To implement strategies to control Palmer amaranth (Amaranthus palmeri S. Wats.) and redroot pigweed (Amaranthus retroflexus L.) infestations in cotton (Gossypium hirsutum L.) production systems, managers need effective techniques to identify the weeds. Leaf light reflectance measurements have shown promise as a tool to distinguish crops from weeds. Studies have targeted plants with green leaves. This study focused on using leaf hyperspectral reflectance data to develop spectral profiles of Palmer amaranth, redroot pigweed, and cotton and to determine regions of the light spectrum most sensitive for pigweed and cotton discrimination. The study focused on cotton near-isogenic lines created to have bronze, green, or yellow colored leaves. Reflectance measurements within the 400 to 2500 nm spectral range were obtained from cotton and weed plants grown in a greenhouse in 2015 and 2016. Two scenarios were evaluated for the comparison: (1) Palmer amaranth versus cotton lines and (2) redroot pigweed versus cotton lines. Statistical significance (p ≤ 0.05) was determined with analysis of variance (ANOVA) and Dunnett’s test. Sensitivity measurements were tabulated to determine the optimal region of the light spectrum for weed and cotton line discrimination. Optimal bands for weed and cotton separation were 600 to 700 nm (both weeds versus cotton bronze and cotton yellow), 710 nm (Palmer amaranth versus cotton green), and 1460 nm (redroot pigweed versus cotton green). Spectral bands were identified for separating Palmer amaranth and redroot pigweed from cotton lines with bronze, green, and yellow leaves. Ground-based and airborne sensors can be tuned into the regions of spectrum identified, facilitating using remote sensing technology for Palmer amaranth and redroot pigweed identification in cotton production systems.
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