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Optimal machining conditions for turning Ti-6Al-4V using response surface methodology

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Advances in Manufacturing 2013年第4期1卷 329-339页

作者： Satyanarayana Kosaraju venu gopal Anne Department of Mechanical Engineering National Institute of TechnologyWarangal

Machining titanium is one of ever-increasing magnitude problems due to its characteristics such as low thermal conductivity, modulus of elasticity and work hardening. The efficient titanium alloy machining involves a proper selection of process parameters to minimize the tangential force （Fz） and surface roughness （Ra）. In the present work, the performance of PVD/TiA1N coated carbide inserts was investigated using response surface methodology （RSM） for turning Ti-6A1-4V. The effects of process parameters such as speed （v）, feed （/＇）, depth of cut （d） and back rake angle （Ty） on Fz and Ra were investi- gated. The experimental plan used for four factors and three levels was designed based on face centered, central composite design （CCD）. The experimental results indi- cated that Fz increased with the increase in d, f and decreased with the increase in v and yy, whereas Ra decreased with the increase in v and 7y, and increased with d and v. The goodness of fit of the regression equations and model fits （R2） for Fz and Ra were found to be 0.968 and 0.970, which demonstrated that it was an effective model. A confirmation test was also conducted in order to verify the correctness of the model.

关键词： Ti-6Al-4V - Response surfacemethodology ~ Cutting force ~ Surface roughness

HIGH ACCURACY ARITHMETIC AVERAGE TYPE DISCRETIZATION FOR THE SOLUTION OF TWO-SPACE DIMENSIONAL NONLINEAR WAVE EQUATIONS

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International Journal of Modeling, Simulation, and Scientific Computing 2012年第2期3卷 1-18页

作者： R.K.MOHANTY venu gopal Department of Mathematics University of Delhi Delhi-110007India

In this paper,we propose a new high accuracy discretization based on the ideas given by Chawla and Shivakumar for the solution of two-space dimensional nonlinear hyper-bolic partial differential equation of the form utt=A(x,y,t)uxx+B(x,y,t)uyy+g(x,y,t,u,ux,uy,ut),00 subject to appropriate initial and Dirichlet boundary *** use only five evaluations of the function g and do not require any fictitious points to discretize the differential *** proposed method is directly applicable to wave equation in polar coordinates and when applied to a linear telegraphic hyperbolic equation is shown to be unconditionally *** results are provided to illustrate the usefulness of the proposed method.

关键词： Nonlinear hyperbolic equation variable coefficients arithmetic average type approximation wave equation in polar coordinates van der Pol equation telegraphic equation maximum absolute errors.

Geometric grid network and third-order compact scheme for solving nonlinear variable coefficients 3D elliptic PDEs

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International Journal of Modeling, Simulation, and Scientific Computing 2018年第6期9卷 72-99页

作者： Navnit Jha venu gopal Bhagat Singh Department of Mathematics South Asian University ChanakyapuriNew Delhi 110070India The School of Mathematical Sciences University of Science and Technology of China Hefei Anhui 230026P.R.China

By using nonuniform(geometric)grid network,a new high-order finite-difference compact scheme has been obtained for the numerical solution of three-space dimensions partial differential equations of elliptic *** cell discretization to the elliptic equation makes it easier to compute and exhibit stability of the numerical *** monotone and irreducible property of the Jacobian matrix to the system of difference equations analyses the converging behavior of the numerical solution *** an experiment,applications of the compact scheme to Schr¨odinger equations,sine-Gordon equations,elliptic Allen–Cahn equation and Poisson’s equation have been presented with root mean squared errors of exact and approximate solution *** results corroborate the reliability and efficiency of the scheme.

关键词： Finite-difference method nonuniform grid compact operator monotone matrix sine-Gordon equation elliptic Allen-Cahn equation.

Response of colloidal liquids containing magnetic holes of different volume densities to magnetic field characterized by transmission measurement

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Chinese Physics B 2010年第10期19卷 541-549页

作者：邓海东孙婷赵韦人符志成戴峭峰吴立军兰胜 Achanta venu gopal Laboratory of Photonic Information Technology School for Information and Optoelectronic Science and Engineering South China Normal University College of Science South China Agricultural University School of Physics and Optoelectronics Guangdong University of Technology Department of Condensed Matter Physics and Material Science Tata Institute of Fundamental Research Homi Bhabha Road Mumbai 400005 India

This paper systematically investigates the response of colloidal liquids containing magnetic holes of different volume densities to magnetic field by conventional transmission measurements. It finds that the enhancement in the transmission of such a colloidal liquid under a magnetic field exhibits a strong dependence on the volume density of magnetic holes. A linear increase in the maximum enhancement factor is observed when the volume density of magnetic holes is below a critical level at which a maximum enhancement factor of ~150 is achieved in the near infrared region. Once the volume density of magnetic holes exceeds the critical level, a sharp drop of the maximum enhancement factor to ~2 is observed. After that, the maximum enhancement factor increases gradually till a large volume density of ~9%. By monitoring the arrangement of magnetic holes under a magnetic field, it reveals that the colloidal liquids can be classified into three different phases, i.e., the gas-like, liquid-like and solid-like phases, depending on the volume density of magnetic holes. The response behaviour of colloidal liquids to magnetic field is determined by the interaction between magnetic holes which is governed mainly by their volume density. A phase transition, which is manifested in the dramatic reduction in the maximum enhancement factor, is clearly observed between the liquid-like and solid-like phases. The optical switching operations for colloidal liquids in different phases are compared and the underlying physical mechanisms are discussed.

关键词： magnetic holes phases change optical switching operations

Modification of the spontaneous emission of quantum dots near the surface of a three-dimensional colloidal photonic crystal

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Chinese Physics B 2010年第11期19卷 441-447页

作者：刘正奇冯天华戴峭峰吴立军兰胜丁才蓉汪河洲 gopal Achanta venu Laboratory of Photonic Information Technology School for Information and Optoelectronic Science and EngineeringSouth China Normal University State Key Laboratory of Optoelectronic Materials and Technologies Zhongshan (Sun Yat-Sen) University Department of Condensed Matter Physics and Material Science Tata Institute of Fundamental ResearchHomi Bhabha RoadMumbai 400005India

This paper demonstrates experimentally and numerically that a significant modification of spontaneous emission rate can be achieved near the surface of a three-dimensional photonic crystal. In experiments, semiconductor coreshell quantum dots are intentionally confined in a thin polymer film on which a three-dimensional colloidal photonic crystal is fabricated. The spontaneous emission rate of quantum dots is characterised by conventional and time-resolved photoluminescence （PL） measurements. The modification of the spontaneous emission rate, which is reflected in the change of spectral shape and PL lifetime, is clearly observed. While an obvious increase in the PL lifetime is found at most wavelengths in the band gap, a significant reduction in the PL lifetime by one order of magnitude is observed at the short-wavelength band edge. Numerical simulation reveals a periodic modulation of spontaneous emission rate with decreasing modulation strength when an emitter is moved away from the surface of the photonic crystal. It is supported by the fact that the modification of spontaneous emission rate is not pronounced for quantum dots distributed in a thick polymer film where both enhancement and suppression are present simultaneously. This finding provides a simple and effective way for improving the performance of light emitting devices.

关键词： spontaneous emission colloidal photonic crystal semiconductor quantum dot time-resolved photoluminescence

A Novel RP-HPLC Method for Estimating Fulvestrant, Benzoyl Alcohol, and Benzyl Benzoate in Injection Formulation

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American Journal of Analytical Chemistry 2022年第7期13卷 229-240页

作者： Arjuna Rao Nekkalapudi venu gopal Veldi Sreenivas Pippalla Career Point University CP Tower 1 IPIA Kota Rajasthan India HTS Bio Pharma Aleap Industries Estate Pragathi Nagar Telangana India Sikkim Professional University Gangtok India

For the quantitative determination of Fulvestrant, Benzyl alcohol, and Benzyl benzoate in Fulvestrant injection, an original RP-HPLC approach was developed. The gradient method was developed using HPLC and a Phenomenex Luna C8, 150 × 4.6 mm, i.d 3.0 μm particle size column with a gradient programme of mobile phases A and B. With a flow rate of 1.5 mL/minute, injection volume of 10 μL, and column temperature of 35°C, UV wavelength detection at 254 nm for Benzyl alcohol and Benzoyl Benzoate and 280 nm for Fulvestrant, mobile phase-A consists of DI water and mobile phase-B consists of Acetonitrile. The current study describes a single HPLC method for developing a Fulvestrant (Active), Benzyl alcohol (Cosolvent), and Benzyl Benzoate (Cosolvent) assay for Fulvestrant injection. The assay method was determined to be suitable for quantifying three components in the pharmaceutical product and was verified according to ICH guidelines.

关键词： Fulvestrant Injection Formulation HPLC Assay Benzyl Alcohol and Benzyl Benzoate