Vaibhav Kumar - Academia.edu (original) (raw)
Address: Mumbai, Maharashtra, India
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High Performance Computers are essential tools of trade in modern day science. The current resear... more High Performance Computers are essential tools of trade in modern day science. The current research problems scientists and engineers are attempting to solve are becoming increasingly complex and are beyond the reach of traditional laboratory style experimental methodologies. Access to supercomputers makes a great deal of difference as they help in dealing with very high resolution models which result in accurate simulations of the phenomena that one is trying to investigate, in reasonable timeframes. This, in turn helps in cutting down the number of experiments that one has to conduct and also in arriving at accurate inferences at a faster rate. The Computer Division of the Bhabha Atomic Research Centre (BARC) has been developing high performance parallel computers for its scientists and engineers for over a decade. The latest in the ANUPAM series of parallel supercomputers is called ‘Anupam-Ameya’, a 512-processor cluster running Linux. This paper describes the design goals, architecture, components and benchmarking figures of the Anupam-Ameya cluster.
Experiments in Fluids, 2011
A technique to provide simultaneous measurement on both free surface topography and the velocity ... more A technique to provide simultaneous measurement on both free surface topography and the velocity vector field of free surface flows is further developed and validated. Testing was performed on the topography measurement by imaging static plastic wave samples over a wide range of amplitudes. Analysis on the accuracy of the topography reconstruction, the sensitivity to noise and the dependence on spatial resolution are presented. The displacement of the free surface is insensitive to noisy input and the sensitivity shows a linear dependence with the sample spacing. Simultaneous measurements of the free surface and associated velocity field in the wake of a circular cylinder are presented for Reynolds numbers between 55 and 100.
Experiments in Fluids, 2011
This paper examines the shock cell structure, vorticity and velocity field at the exit of an unde... more This paper examines the shock cell structure, vorticity and velocity field at the exit of an underexpanded jet nozzle using a hydraulic analogy and the Reference Image Topography technique. Understanding the flow in this region is important for the mitigation of screech, an aeroacoustic problem harmful to aircraft structures. Experiments are conducted on a water table, allowing detailed quantitative investigation of this important flow regime at a greatly reduced expense. Conventional Particle Image Velocimetry is employed to determine the velocity and vorticity fields of the nozzle exit region. Applying Reference Image Topography, the wavy water surface is reconstructed and when combined with the hydraulic analogy, provides a pressure map of the region. With this approach subtraction of surfaces is used to highlight the unsteady regions of the flow, which is not as convenient or quantitative with conventional Schlieren techniques. This allows a detailed analysis of the shock cell structures and their interaction with flow instabilities in the shear layer that are the underlying cause of jet screech.
This paper presents an overview of the developments made in the field of oversampling sigma-delta... more This paper presents an overview of the developments made in the field of oversampling sigma-delta (SigmaDelta) data converters. Further, an approach to model a 4th order multi-bit SigmaDelta ADC using Simulink, Matlab is proposed. It is shown that behavioral modeling provides comparable accurate results, and is much faster in comparison to spectre based simulations.
A design procedure for an operational amplifier using indirect compensation is presented in this ... more A design procedure for an operational amplifier using indirect compensation is presented in this paper. Indirect compensation has inherent benefits in regards with power to speed trade-off. The technique has been seldom used in the past because a clear methodology for designing such an amplifier has not been provided. This paper develops the mathematical and analytical insight for designing an operational amplifier with this technique. The paper also provides a design strategy and an example to illustrate the use of the proposed design procedure.
This paper presents an overview of the developments made in the field of oversampling sigma-delta... more This paper presents an overview of the developments made in the field of oversampling sigma-delta (SigmaDelta) data converters. Further, an approach to model a 4th order multi-bit SigmaDelta ADC using Simulink, Matlab is proposed. It is shown that behavioral modeling provides comparable accurate results, and is much faster in comparison to spectre based simulations.
High Performance Computers are essential tools of trade in modern day science. The current resear... more High Performance Computers are essential tools of trade in modern day science. The current research problems scientists and engineers are attempting to solve are becoming increasingly complex and are beyond the reach of traditional laboratory style experimental methodologies. Access to supercomputers makes a great deal of difference as they help in dealing with very high resolution models which result in accurate simulations of the phenomena that one is trying to investigate, in reasonable timeframes. This, in turn helps in cutting down the number of experiments that one has to conduct and also in arriving at accurate inferences at a faster rate. The Computer Division of the Bhabha Atomic Research Centre (BARC) has been developing high performance parallel computers for its scientists and engineers for over a decade. The latest in the ANUPAM series of parallel supercomputers is called ‘Anupam-Ameya’, a 512-processor cluster running Linux. This paper describes the design goals, architecture, components and benchmarking figures of the Anupam-Ameya cluster.
Experiments in Fluids, 2011
A technique to provide simultaneous measurement on both free surface topography and the velocity ... more A technique to provide simultaneous measurement on both free surface topography and the velocity vector field of free surface flows is further developed and validated. Testing was performed on the topography measurement by imaging static plastic wave samples over a wide range of amplitudes. Analysis on the accuracy of the topography reconstruction, the sensitivity to noise and the dependence on spatial resolution are presented. The displacement of the free surface is insensitive to noisy input and the sensitivity shows a linear dependence with the sample spacing. Simultaneous measurements of the free surface and associated velocity field in the wake of a circular cylinder are presented for Reynolds numbers between 55 and 100.
Experiments in Fluids, 2011
This paper examines the shock cell structure, vorticity and velocity field at the exit of an unde... more This paper examines the shock cell structure, vorticity and velocity field at the exit of an underexpanded jet nozzle using a hydraulic analogy and the Reference Image Topography technique. Understanding the flow in this region is important for the mitigation of screech, an aeroacoustic problem harmful to aircraft structures. Experiments are conducted on a water table, allowing detailed quantitative investigation of this important flow regime at a greatly reduced expense. Conventional Particle Image Velocimetry is employed to determine the velocity and vorticity fields of the nozzle exit region. Applying Reference Image Topography, the wavy water surface is reconstructed and when combined with the hydraulic analogy, provides a pressure map of the region. With this approach subtraction of surfaces is used to highlight the unsteady regions of the flow, which is not as convenient or quantitative with conventional Schlieren techniques. This allows a detailed analysis of the shock cell structures and their interaction with flow instabilities in the shear layer that are the underlying cause of jet screech.
This paper presents an overview of the developments made in the field of oversampling sigma-delta... more This paper presents an overview of the developments made in the field of oversampling sigma-delta (SigmaDelta) data converters. Further, an approach to model a 4th order multi-bit SigmaDelta ADC using Simulink, Matlab is proposed. It is shown that behavioral modeling provides comparable accurate results, and is much faster in comparison to spectre based simulations.
A design procedure for an operational amplifier using indirect compensation is presented in this ... more A design procedure for an operational amplifier using indirect compensation is presented in this paper. Indirect compensation has inherent benefits in regards with power to speed trade-off. The technique has been seldom used in the past because a clear methodology for designing such an amplifier has not been provided. This paper develops the mathematical and analytical insight for designing an operational amplifier with this technique. The paper also provides a design strategy and an example to illustrate the use of the proposed design procedure.
This paper presents an overview of the developments made in the field of oversampling sigma-delta... more This paper presents an overview of the developments made in the field of oversampling sigma-delta (SigmaDelta) data converters. Further, an approach to model a 4th order multi-bit SigmaDelta ADC using Simulink, Matlab is proposed. It is shown that behavioral modeling provides comparable accurate results, and is much faster in comparison to spectre based simulations.