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Search Results: 1 - 10 of 223956 matches for " R. Shivakumar "
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Ant Lion Optimization Approach for Load Frequency Control of Multi-Area Interconnected Power Systems  [PDF]
R. Satheeshkumar, R. Shivakumar
Circuits and Systems (CS) , 2016, DOI: 10.4236/cs.2016.79206
Abstract: This work proposes a novel nature-inspired algorithm called Ant Lion Optimizer (ALO). The ALO algorithm mimics the search mechanism of antlions in nature. A time domain based objective function is established to tune the parameters of the PI controller based LFC, which is solved by the proposed ALO algorithm to reach the most convenient solutions. A three-area interconnected power system is investigated as a test system under various loading conditions to confirm the effectiveness of the suggested algorithm. Simulation results are given to show the enhanced performance of the developed ALO algorithm based controllers in comparison with Genetic Algorithm (GA), Particle Swarm Optimization (PSO), Bat Algorithm (BAT) and conventional PI controller. These results represent that the proposed BAT algorithm tuned PI controller offers better performance over other soft computing algorithms in conditions of settling times and several performance indices.
Implementation of an Innovative Bio Inspired GA and PSO Algorithm for Controller design considering Steam GT Dynamics
R. Shivakumar,R. Lakshmipathi
International Journal of Computer Science Issues , 2010,
Abstract: The Application of Bio Inspired Algorithms to complicated Power System Stability Problems has recently attracted the researchers in the field of Artificial Intelligence. Low frequency oscillations after a disturbance in a Power system, if not sufficiently damped, can drive the system unstable. This paper provides a systematic procedure to damp the low frequency oscillations based on Bio Inspired Genetic (GA) and Particle Swarm Optimization (PSO) algorithms. The proposed controller design is based on formulating a System Damping ratio enhancement based Optimization criterion to compute the optimal controller parameters for better stability. The Novel and contrasting feature of this work is the mathematical modeling and simulation of the Synchronous generator model including the Steam Governor Turbine (GT) dynamics. To show the robustness of the proposed controller, Non linear Time domain simulations have been carried out under various system operating conditions. Also, a detailed Comparative study has been done to show the superiority of the Bio inspired algorithm based controllers over the Conventional Lead lag controller.
Implementation of an Innovative Bio Inspired GA and PSO Algorithm for Controller design considering Steam GT Dynamics
R. Shivakumar,R. Lakshmipathi
Computer Science , 2010,
Abstract: The Application of Bio Inspired Algorithms to complicated Power System Stability Problems has recently attracted the researchers in the field of Artificial Intelligence. Low frequency oscillations after a disturbance in a Power system, if not sufficiently damped, can drive the system unstable. This paper provides a systematic procedure to damp the low frequency oscillations based on Bio Inspired Genetic (GA) and Particle Swarm Optimization (PSO) algorithms. The proposed controller design is based on formulating a System Damping ratio enhancement based Optimization criterion to compute the optimal controller parameters for better stability. The Novel and contrasting feature of this work is the mathematical modeling and simulation of the Synchronous generator model including the Steam Governor Turbine (GT) dynamics. To show the robustness of the proposed controller, Non linear Time domain simulations have been carried out under various system operating conditions. Also, a detailed Comparative study has been done to show the superiority of the Bio inspired algorithm based controllers over the Conventional Lead lag controller.
UPLCMS Method Development and Validation of Amlodipine, Hydrochlorthiazide and Losartan in Combined Tablet Dosage Form  [PDF]
Anandkumar R. Tengli, G. Shivakumar, B. M. Gurupadayya
American Journal of Analytical Chemistry (AJAC) , 2015, DOI: 10.4236/ajac.2015.63021
Abstract: A simple, rapid, sensitive and specific UPLCMS method was developed and validated following ICH guidelines for simultaneous estimation of tablet dosage form containing amlodipine (AMLO) hydrochlorothiazide (HCT) and losartan (LOSAT) using telmisartan (TELMI) as an internal standard (IS). The separation was achieved using Waters ACQUITY BEH C18 (1.7 μm, 2.1 × 50 mm) column with gradient mode, mobile phase containing acetonitrile (A) & 1% ammonium acetate (B) pH adjusted to 2.8 with trifluoro acetic acid with gradient mode. The flow rate was 0.4 mL·mL﹣1 and the injection volume 2 μl. The retention time for amlodipine, hydrochlorothiazide and losartan was found to be 3.7, 2.5 and 3.9 min, respectively. The developed method was found to be linear over the concentration range of 50 - 300 ng·mL﹣1, 125 - 750 ng·mL﹣1 and 500 - 3000 ng·mL﹣1 for AMLO, HCT and LOSAT respectively. The signal intensities obtained in ion mode for amlodipine, hydrochlorothiazide, losartan and telmisartan (IS) they were found to be much higher positive ion mode (M+)﹣ parent ion at m/z, 409.02, 297.97, 422.91 and 515.03, respectively, in QUATTROZQ full scan mass spectra.
Power System Stability Enhancement by Neuro Fuzzy Logic Based SVC for Multi Machine System
S. Sabna,,D. Prasad,,R. Shivakumar
International Journal of Engineering and Advanced Technology , 2012,
Abstract: This paper presents a hybrid technique to small signal stability enhancement using ANFIS thruster susceptance control of static vary compensator (SVC). Their main objective is to determine the synchronous generator’s ability to maintain stability after the occurrence of a fault or following a major change in the network such as the loss of an important generator or a large load. Static vary compensator is proven the fact that it improves the dynamic stability of power system apart from reactive power compensation; it has multiple role in the operation of power system. The main variable to be controlled in the power system for efficient operation is to mitigating the rotor electro-mechanical low frequency oscillations. Simulations are carried out for multi machine power system for without SVC and with ANFIS SVC. The proposed Neuro fuzzy logic based SVC for multi machine power system provides better damping to power system oscillation.
Leptospirosis laboratory, Madras medical college: Review of our experience (2004-2006)
Sumathi G,Narayanan R,Shivakumar S
Indian Journal of Medical Microbiology , 2008,
Abstract:
Formulation optimization of propranolol hydrochloride microcapsules employing central composite design
Shivakumar H,Patel R,Desai B
Indian Journal of Pharmaceutical Sciences , 2008,
Abstract: A central composite design was employed to produce microcapsules of propranolol hydrochloride by o/o emulsion solvent evaporation technique using a mixture of cellulose acetate butyrate as coat material and span-80 as an emulsifier. The effect of formulation variables namely levels of cellulose acetate butyrate (X 1 ) and percentage of Span-80 (X 2 ) on encapsulation efficiency (Y 1 ), drug release at the end of 1.5 h (Y 2 ), 4 h (Y 3 ), 8 h (Y 4 ), 14 h (Y 5 ), and 24 h (Y 6 ) were evaluated using the F test. Mathematical models containing only the significant terms were generated for each response parameter using multiple linear regression analysis and analysis of variance. Both the formulation variables exerted a significant influence (P < 0.05) on Y 1 whereas the cellulose acetate butyrate level emerged as the lone factor which significantly influenced the other response parameters. Numerical optimization using desirability approach was employed to develop an optimized formulation by setting constraints on the dependent and independent variables. The experimental values of Y 1 , Y 2 , Y 3 , Y 4 , Y 5 , and Y 6 for the optimized formulation was found to be 92.86±1.56% w/w, 29.58±1.22%, 48.56±2.56%, 60.85±2.35%, 76.23±3.16% and 95.12±2.41%, respectively which were in close agreement with those predicted by the mathematical models. The drug release from microcapsules followed first order kinetics and was characterized by Higuchi diffusion model. The optimized microcapsule formulation developed was found to comply with the USP drug release test-1 for extended release propranolol hydrochloride capsules.
Tensile Properties of Veins of Damselfly Wing  [PDF]
Rupan Talucdher, Kunigal Shivakumar
Journal of Biomaterials and Nanobiotechnology (JBNB) , 2013, DOI: 10.4236/jbnb.2013.43031
Abstract: Microtension test of Costa and Radius veins of damselfly wing was conducted to measure tensile strength and modulus. The specimens were classified into fresh and dry depending on when the samples were prepared and tested. Fresh samples tested immediately after extracting from the fly while the dry samples were tested one year after extraction and stored in a desiccator. Measured load-displacement response and fracture load were used to calculate modulus and strength. Field Emission Scanning Electron Microscope was used to measure the fracture morphology and cross-section of the vein. The results showed that the veins are brittle and fracture surface is flat. The average strength (232 - 285 MPa) and modulus (14 - 17 GPa) of the Costa and Radius veins were nearly same for both fresh and dry samples. The tensile modulus of the veins was 8% - 10% higher than the indentation (compressive) modulus and was nearly the same as that of human bones.
Etiology and antibacterial susceptibility pattern of community-acquired bacterial ocular infections in a tertiary eye care hospital in south India
Bharathi M,Ramakrishnan R,Shivakumar C,Meenakshi R
Indian Journal of Ophthalmology , 2010,
Abstract: Aims: To identify the etiology, incidence and prevalence of ocular bacterial infections, and to assess the in vitro susceptibility of these ocular bacterial isolates to commonly used antibiotics. Materials and Methods: Retrospective analysis of consecutive samples submitted for microbiological evaluation from patients who were clinically diagnosed with ocular infections and were treated at a tertiary eye care referral center in South India between January 2002 and December 2007. Results: A total of 4417 ocular samples was submitted for microbiological evaluation, of which 2599 (58.8%) had bacterial growth, 456 (10.3%) had fungal growth, 15 (0.34%) had acanthamoebic growth, 14 (0.32%) had mixed microbial growth and the remaining 1333 (30.2%) had negative growth. The rate of culture-positivity was found to be 88% (P < 0.001) in eyelids′ infection, 70% in conjunctival, 69% in lacrimal apparatus, 67.4% in corneal, 51.6% in intraocular tissues, 42.9% in orbital and 39.2% in scleral infections. The most common bacterial species isolated were Staphylococcus aureus (26.69%) followed by Streptococcus pneumoniae (22.14%). Sta. aureus was more prevalent more in eyelid infections (51.22%; P = 0.001) coagulase-negative staphylococci in endophthalmitis (53.1%; P = 0.001), Str. pneumoniae in lacrimal apparatus and corneal infections (64.19%; P = 0.001), Corynebacterium species in blepharitis and conjunctivitis (71%; P = 0.001), Pseudomonas aeruginosa in keratitis and dacryocystitis (66.5%; P = 0.001), Haemophilus species in dacryocystitis and conjunctivitis (66.7%; P = 0.001), Moraxella lacunata in blepharitis (54.17%; P = 0.001) and Moraxella catarrhalis in dacryocystitis (63.83%; P = 0.001). The largest number of gram-positive isolates was susceptible to moxifloxacin (98.7%) and vancomycin (97.9%), and gram-negative isolates to amikacin (93.5%) and gatifloxacin (92.7%). Conclusions: Gram-positive cocci were the most frequent bacteria isolated from ocular infections and were sensitive to moxifloxacin and vancomycin, while gram-negative isolates were more sensitive to amikacin and gatifloxacin.
Epidemic Spreading on Preferred Degree Adaptive Networks
Shivakumar Jolad, Wenjia Liu, B. Schmittmann, R. K. P. Zia
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0048686
Abstract: We study the standard SIS model of epidemic spreading on networks where individuals have a fluctuating number of connections around a preferred degree . Using very simple rules for forming such preferred degree networks, we find some unusual statistical properties not found in familiar Erd?s-Rényi or scale free networks. By letting depend on the fraction of infected individuals, we model the behavioral changes in response to how the extent of the epidemic is perceived. In our models, the behavioral adaptations can be either ‘blind’ or ‘selective’ – depending on whether a node adapts by cutting or adding links to randomly chosen partners or selectively, based on the state of the partner. For a frozen preferred network, we find that the infection threshold follows the heterogeneous mean field result and the phase diagram matches the predictions of the annealed adjacency matrix (AAM) approach. With ‘blind’ adaptations, although the epidemic threshold remains unchanged, the infection level is substantially affected, depending on the details of the adaptation. The ‘selective’ adaptive SIS models are most interesting. Both the threshold and the level of infection changes, controlled not only by how the adaptations are implemented but also how often the nodes cut/add links (compared to the time scales of the epidemic spreading). A simple mean field theory is presented for the selective adaptations which capture the qualitative and some of the quantitative features of the infection phase diagram.
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