ratheesh as - Academia.edu (original) (raw)

Papers by ratheesh as

Research paper thumbnail of Comparison of FPGA and GPU implementations of real-time stereo vision

Real-time stereo vision systems have many applicationsfrom autonomous navigation for vehicles thr... more Real-time stereo vision systems have many applicationsfrom autonomous navigation for vehicles through surveillance to materials handling. Accurate scene interpretation depends on an ability to process high resolution images in real-time, but, although the calculations for stereo matching are basically simple, a practical system needs to evaluate at least 10 9 disparities every second -beyond the capability of a single processor. Stereo correspondence algorithms have high degrees of inherent parallelism and are thus good candidates for parallel implementations. In this paper, we compare the performance obtainable with an FPGA and a GPU to understand the trade-off between the flexibility but relatively low speed of an FPGA and the high speed and fixed architecture of the GPU. Our comparison highlights the relative strengths and limitations of the two systems. Our experiments show that, for a range of image sizes, the GPU manages 2 × 10 9 disparities per second, compared with 2.6 × 10 9 disparities per second for an FPGA.

Research paper thumbnail of Thermal diffusion of Cu into In 2Se 3: A better approach to SEL technique in the deposition of CuInSe 2 thin films

Solar Energy Materials and Solar Cells, 2006

This paper reports the modifications made in the preparation techniques of getting CuInSe 2 thin ... more This paper reports the modifications made in the preparation techniques of getting CuInSe 2 thin films starting with chemical bath deposited (CBD) selenium films. In the present study, CBD Se film was converted into CuInSe 2 by stacked elemental layer (SEL) technique and also by thermal diffusion of Cu into In 2 Se 3 . In both the cases CBD Se films were used to avoid toxic Se vapor and H 2 Se gas. Improvements were made in these techniques through a detailed study, varying the composition of the films over a wide range by changing the Cu/In ratio. Structural, optical and electrical characterizations were performed. On comparing the material properties of CuInSe 2 deposited by these two techniques, it was found that photosensitivity was better for samples prepared by thermal diffusion of Cu into In 2 Se 3 . So the technique of thermal diffusion of Cu into In 2 Se 3 was found to be better than SEL technique in the preparation of CuInSe 2 using CBD Se. Cu-rich, In-rich and nearly stoichiometric samples could be prepared by thermal diffusion of Cu into In 2 Se 3 . These samples were analyzed using energy dispersive spectroscopy, Raman spectroscopy and atomic force microscopy also. r

Research paper thumbnail of SHI induced single-phase InSe formation at lower annealing temperature

Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms, 2006

In/Se bilayer films, irradiated using 40 MeV silicon ions, with a fluence of 1 · 10 13 ions/cm 2 ... more In/Se bilayer films, irradiated using 40 MeV silicon ions, with a fluence of 1 · 10 13 ions/cm 2 , were vacuum annealed at 50°C and 100°C for 1 h. Optical and structural properties were studied using optical absorption and X-ray diffraction measurements respectively. Irradiated sample, annealed at 50°C had both InSe and In 2 Se 3 phases. Annealing the sample at 100°C resulted in the elimination of In 2 Se 3 phase and formation of InSe along (0 0 6) plane in the irradiated system. Absorption measurements also showed only one absorption edge, corresponding to InSe phase. In the case of un-irradiated In/Se system, annealing at 400°C for 1 h was required to obtain single-phase indium selenide. Thus it was observed that single-phase indium selenide was formed at much lower annealing temperature in irradiated system in comparison with un-irradiated system.

Research paper thumbnail of Microwave dielectric properties of PTFE/rutile nanocomposites

Journal of Alloys and Compounds, 2009

The effects of nano-size rutile filler on the microwave dielectric properties of PTFE composites ... more The effects of nano-size rutile filler on the microwave dielectric properties of PTFE composites were investigated and the results were compared with that of micron size rutile filled composites. Nano-size rutile powder was prepared through sol-gel route and the filled PTFE composites were fabricated through SMECH process. Different characterization techniques such as powder X-ray diffraction, SEM, BET, TEM and TG/DSC were employed to analyze the nature of ceramic filler. The dielectric properties of filled composites were evaluated at microwave frequency region using waveguide cavity perturbation technique. Different theoretical models have been employed to predict the variation of dielectric constant with respect to filler loading. The moisture absorption characteristics of nano-rutile filled PTFE composites were measured as per IPC-TM-650 2.6.2 standards. Composites show high dielectric constant at X-band frequency region with relatively high loss tangent compared to micron size counterpart.

Research paper thumbnail of Comparison of FPGA and GPU implementations of real-time stereo vision

Real-time stereo vision systems have many applicationsfrom autonomous navigation for vehicles thr... more Real-time stereo vision systems have many applicationsfrom autonomous navigation for vehicles through surveillance to materials handling. Accurate scene interpretation depends on an ability to process high resolution images in real-time, but, although the calculations for stereo matching are basically simple, a practical system needs to evaluate at least 10 9 disparities every second -beyond the capability of a single processor. Stereo correspondence algorithms have high degrees of inherent parallelism and are thus good candidates for parallel implementations. In this paper, we compare the performance obtainable with an FPGA and a GPU to understand the trade-off between the flexibility but relatively low speed of an FPGA and the high speed and fixed architecture of the GPU. Our comparison highlights the relative strengths and limitations of the two systems. Our experiments show that, for a range of image sizes, the GPU manages 2 × 10 9 disparities per second, compared with 2.6 × 10 9 disparities per second for an FPGA.

Research paper thumbnail of Thermal diffusion of Cu into In 2Se 3: A better approach to SEL technique in the deposition of CuInSe 2 thin films

Solar Energy Materials and Solar Cells, 2006

This paper reports the modifications made in the preparation techniques of getting CuInSe 2 thin ... more This paper reports the modifications made in the preparation techniques of getting CuInSe 2 thin films starting with chemical bath deposited (CBD) selenium films. In the present study, CBD Se film was converted into CuInSe 2 by stacked elemental layer (SEL) technique and also by thermal diffusion of Cu into In 2 Se 3 . In both the cases CBD Se films were used to avoid toxic Se vapor and H 2 Se gas. Improvements were made in these techniques through a detailed study, varying the composition of the films over a wide range by changing the Cu/In ratio. Structural, optical and electrical characterizations were performed. On comparing the material properties of CuInSe 2 deposited by these two techniques, it was found that photosensitivity was better for samples prepared by thermal diffusion of Cu into In 2 Se 3 . So the technique of thermal diffusion of Cu into In 2 Se 3 was found to be better than SEL technique in the preparation of CuInSe 2 using CBD Se. Cu-rich, In-rich and nearly stoichiometric samples could be prepared by thermal diffusion of Cu into In 2 Se 3 . These samples were analyzed using energy dispersive spectroscopy, Raman spectroscopy and atomic force microscopy also. r

Research paper thumbnail of SHI induced single-phase InSe formation at lower annealing temperature

Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms, 2006

In/Se bilayer films, irradiated using 40 MeV silicon ions, with a fluence of 1 · 10 13 ions/cm 2 ... more In/Se bilayer films, irradiated using 40 MeV silicon ions, with a fluence of 1 · 10 13 ions/cm 2 , were vacuum annealed at 50°C and 100°C for 1 h. Optical and structural properties were studied using optical absorption and X-ray diffraction measurements respectively. Irradiated sample, annealed at 50°C had both InSe and In 2 Se 3 phases. Annealing the sample at 100°C resulted in the elimination of In 2 Se 3 phase and formation of InSe along (0 0 6) plane in the irradiated system. Absorption measurements also showed only one absorption edge, corresponding to InSe phase. In the case of un-irradiated In/Se system, annealing at 400°C for 1 h was required to obtain single-phase indium selenide. Thus it was observed that single-phase indium selenide was formed at much lower annealing temperature in irradiated system in comparison with un-irradiated system.

Research paper thumbnail of Microwave dielectric properties of PTFE/rutile nanocomposites

Journal of Alloys and Compounds, 2009

The effects of nano-size rutile filler on the microwave dielectric properties of PTFE composites ... more The effects of nano-size rutile filler on the microwave dielectric properties of PTFE composites were investigated and the results were compared with that of micron size rutile filled composites. Nano-size rutile powder was prepared through sol-gel route and the filled PTFE composites were fabricated through SMECH process. Different characterization techniques such as powder X-ray diffraction, SEM, BET, TEM and TG/DSC were employed to analyze the nature of ceramic filler. The dielectric properties of filled composites were evaluated at microwave frequency region using waveguide cavity perturbation technique. Different theoretical models have been employed to predict the variation of dielectric constant with respect to filler loading. The moisture absorption characteristics of nano-rutile filled PTFE composites were measured as per IPC-TM-650 2.6.2 standards. Composites show high dielectric constant at X-band frequency region with relatively high loss tangent compared to micron size counterpart.