Informatics Publishing Limited

S. Ganapaty , P. Steve Thomas , P. Sudheer , K. V. Ramana , Peter G. Waterman

Abstract

Objective : The genus Tephrosia is a rich source for unusual flavonoids. The present work is aimed to isolate new molecules of biological interest. Materials and methods : The ischolar_main powder of T. procumbens was extracted with chloroform and concentrated. The residue was subjected to column chromatography and fractional crystallization by organic solvents and their mixtures of increasing polarity which afforded crystalline compounds and were identified by spectroscopic methods. Results and conclusions : Among the isolates, two candidates calopogonium isoflavone B and 2', 7' 8-trimethoxy-4' , 5' -methylenedioxy isoflavone are reported for the first time from this species.

Keywords

Tephrosia procumbens, Flavonoids

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S. Ganapaty , P. S. Thomas , K. V. Ramana , K. Vidyadhar , V. Chakradhar

Abstract

A review of phytoconstituents and biological activities of Cassia species has been presented, considering the fact that there are about 580 species of this genus distributed all around the world. Only 46 species have been studied phytochemically. Hence an attempt is made to present a review on the phytochemical studies of Cassis sepcies which still remains as a potential source for bioactive molecules.

Keywords

Cassia Species, Phytochemical and Pharmacological Studies

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S. Ganapaty , B. N. Mallika , S. Balaji , S. V. V. N. S. M. Lakshmi , P. S. Thomas , K. V. Ramana

Abstract

A review of phytoconstituents and biological activities of Digitalis species has been presented. Despite the fact that there are about 24 species of this genus spread around the world, the present survey revealed that only 17 species have been studied phytochemically. Hence an attempt is made to present a review on the phytochemical studies of Digitalis species which would possibly serve as a source for much potent cardioactive molecules.

Keywords

Digitalis Species, Phytochemical, Biological Activity

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K. Sravanthi ¹, K. V. Ramana ², G. Sumalatha ¹, K. Neeraja ³

Affiliations
1 Department of Pharmacology, Hindu College of Pharmacy, Guntur, (A.P), IN
2 Department of Pharmacognosy, A. S. N College of Pharmacy, Guntur, (A.P), IN
3 Department of Pharmacology, Calcutta institute of pharmaceutical t A.H.S, Kolkata, IN

Abstract

The anti-inflammatory effect of the alcoholic extract of Solanum surattense whole plant was assessed in the carrageenan-induced rat paw edema, the antinociceptive effect of the alcoholic extract of Solanum surattense, plant was studied using thermal and chemical-induced pain models using animals, at the doses of 100 and 200 mg/kg body weight. The acute toxicity and the phytochemical constituents of the extract were also determined. The estimated LD50 of the extract was 2gm/kg body weight. Extract significantly (P<0.05), dose-dependently demonstrated anti-inflammatory activity against acute inflammation induced by carrageenan and also the extract significantly (P<0.05) prolonged the pain reaction times in tail flick pain model, and reduced acetic acid-induced writhing. Phytochemical analysis revealed the presence of alkaloids, saponins, flavanoids and carbohydrates in the plant.

Keywords

Analgesic, Anti-inflammatory, Carrageenan, Acute Toxicity, Solanum Surattense

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D. V. A. R. Sastry ¹, K. V. Ramana ¹, N. M. Rao ², P. Pruthvi ¹, D. U. V. Santhosh ¹

Affiliations
1 Dept.of Mech. Engg., K L University, Vaddeswaram, Guntur, IN
2 Dept.of Mech. Engg., University College of Engg., JNTUK, Kakinada, Andhra Pradesh, IN

Abstract

Magnetorheological (MR) dampers are evolving as one of the most promising devices for semi-active vibration control of various dynamic systems. In this paper, the suspension system of a car using MR damper is analysed for 2DOF quarter car and 4DOF half car models and then compared with corresponding suspension system using passive damper for ride comfort and handling. Magnetorheological damper is fabricated using a MR fluid of Carbonyl iron powder and Silicone oil added with additive. Experiments are conducted to establish the behaviour of the MR damper and are used to validate Spencer model for MR damper. Further, using the validated Spencer model of MR damper, the quarter car and half car models of Vehicle Suspension system are simulated by implementing a semi-active suspension system for analysing the resulting displacement and acceleration in the car body. The ride comfort and vehicle handling performance of each specific vehicle model with passive suspension system are compared with corresponding semi-active suspension system. The simulation and analysis are carried out using MATLAB/SIMULINK.

Keywords

Magnetorheological Dampers, Suspension Systems, Spencer Model, Simulation and Fabrication of MR Damper.

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K. I. V. Vandana ¹, K. V. Ramana ¹

Affiliations
1 Dept. of Industrial & Production Engg., Koneru Lakshmaiah College of Engineering, Vaddeswaram, P.O. Guntur Dt-522502, IN

Abstract

With the increasing demand for accurate engineering products, the control of surface texture has become vital. Surface roughness of machined parts need to be specified on the basis of their use and application environment. The geometrical and material properties of surface can significantly affect the friction, wear, fatigue and corrosion of that part. Hence evaluation of surface roughness and characterization of that surface has become essential for design, manufacturing and inspection. Many methods of measuring surface finish have been investigated ranging from simple touch comparator to sophisticated optical techniques. The latest technology of measuring surface roughness is the combination of optical techniques and computer vision systems. In this paper an attempt has been made to develop an experimental technique to measure the surface roughness based on the analysis of the intensity distribution of scattered light from the surface. For this purpose a low cost vision system is proposed. By impinging a laser beam at an angle on the machined surface, a random pattern of bright and dark regions known as speckle is observed. These speckle images are captured using charge coupled device (CCD) camera and are stored in digital format. Further a source code In C++ is developed to read the image data and to compute optical roughness values from stored images. Since the results obtained through this technique are encouraging, this method is well adapted for measurement of rough surface that fall within the range of engineering surface generated by common machining process like grinding, turning and milling. A few conclusions are drawn on the effectiveness of adopting the proposed system.

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M. Gopi Krishna ¹, K. V. Ramana ¹

Affiliations
1 Department of Mechanicai Engineering, K.L. College of Engg. Green fieids, Vaddeswaram, Guntur-522501, IN

Abstract

Present day state of the art in the design of turbo machines has given much scope to the flexible rotor bearing system. The most recurring problem in rotor dynamics is the excessive steady state synchronous vibration levels. Squeeze film dampers (SFD) are the essential components of high-speed turbomachines since they offer the advantage of dissipation of vibration energy and hence prevent rotor dynamic instabilities. A squeeze film damper is used between the bearing and its foundation to reduce the unbalance forces transmitted to the pedestal by introducing an additional damping and there by reduce the amplitude of vibration to acceptable limit. This work highlights the design and development of squeeze film dampers for high-speed machines in a more generic way. The first phase of the work involves the study of the effect of SFD on rotor dynamics based on the parameters like, damping ratio, logarithmic decrement and Transmissibility. A theoretical model Is generated incorporating the said parameters. The dynamic analysis, which is of two fold. Is carried out using ARMD software. The rotor dynamic effects are found without SFD and with SFD. The second phase of the work deals with experimental investigation on a journal-bearing test rig with SFD supports up to a speed of 1800 rpm. At the end, the vibrations obtained through theoretical analysis and experimental investigations are tabulated. It Is concluded that vibration levels are reduced using SFD for the specified optimum inputs.

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D. V. A. Rama Sastry ¹, K. V. Ramana ², N. Mohan Rao ³, M. Phani Kumar ², V. S. S. Rama Chandra Reddy ²

Affiliations
1 Koneru Lakshmaiah Education Foundation, Vaddeswaram, Guntur, Andhra Pradesh, IN
2 Dept. of Mech. Engg., Koneru Lakshmaiah Education Foundation, Vaddeswaram, Guntur, Andhra Pradesh, IN
3 Dept. of Mech. Engg., University College of Engg., JNTUK University, Kakinada, Andhra Pradesh, IN

Abstract

Exposure of human body to vehicular vibrations in transit may lead to the human discomfort. Ride comfort is one of the major issues in design of automobiles. Magneto rheological (MR) dampers are emerging as most feasible solution for various applications in controlling vibrations. An MR damper is a semi-active device, which will offer the advantages of both active and passive suspension. In this study, the MR damper based semi-active suspension system for a car is analysed for ride comfort of 7 degrees of freedom model human body lumped mass, considering head, upper torso, lower torso and pelvis, seated over a seat of a quarter car model and is compared with that of similar system using passive damper. A MR damper is fabricated and is filled with MR fluid made of Carbonyl iron powder and Silicone oil added with additive. Modified Bouc-Wen Model developed by Spencer is used to model the behaviour of MR damper. All the parameters of this model are identified using data acquired from experiments conducted to characterise MR damper. Further, using the Spencer model of MR damper, the human body seated over quarter car is simulated by implementing a semi-active suspension system for analysing the resulting displacement and acceleration of the human body. The ride comfort performance of vehicle model with passive suspension system is compared with corresponding semi-active suspension system. The simulation and analysis are carried out using MATLAB/SIMULINK.

Keywords

Magneto Rheological Dampers, Quarter Car Model, Suspension Systems, Spencer Model, Human Body Vibrations.

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D. V. A. Rama Sastry ¹, K. V. Ramana ¹, N. Mohan Rao ²

Affiliations
1 Koneru Lakshmaiah Education Foundation, Vaddeswaram, Guntur, Andhra Pradesh, IN
2 University College of Engg., JNTUK University, Kakinada, Andhra Pradesh, IN

Abstract

Ride comfort and vehicle handling are the two major issues to be dealt in the design of suspension systems of automobiles. With passive systems offering contrariety on these two parameters, the alternative systems are being in study. Magnetorheological (MR) damper, a most feasible semi-active device, is one such alternative, which will offer the advantage of dealing with both these issues overcoming contrariety. In this study, the suspension system of a car using MR damper is analysed at 5 different currents viz., 0A, 0.25A, 0.5A, 0.75A, 1A, using 2DOF quarter car model and 4DOF half car models for ride comfort and handling and the comparisons of these are done with same suspension system equipped with regular passive damper. A MR damper is built-up using MR fluid consisting of carbonyl iron powder and silicone oil added with additive. Further, the characteristic of this damper is established by conducting experiments, which in turn is used to identify the parameters of Spencer model for MR damper. Using Spencer model of MR damper, at 5 different currents, the quarter car and half car models of vehicle suspension system are simulated by implementing a semi-active suspension system for analysing the resulting displacement and acceleration in the car body. The ride comfort and vehicle handling performance of each specific vehicle model with passive suspension system are compared with corresponding skyhook, ground hook and hybrid based semi-active suspension systems. The simulation and analysis are carried out using Matlab/Simulink.

Keywords

Magnetorheological Dampers, Semi Active Suspension Systems, Spencer Model, Skyhook, Ground Hook Hybrid Control.

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