Ranga Narayanaswami - Academia.edu (original) (raw)

Uploads

Papers by Ranga Narayanaswami

Research paper thumbnail of iDiver: underwater text messaging and locating system for divers

Ocean Sensing and Monitoring IV, 2012

Research paper thumbnail of Sensor fusion and feature-based human/animal classification for Unattended Ground Sensors

2010 IEEE International Conference on Technologies for Homeland Security (HST), 2010

... alarms, thereby improving border security as well as reducing the workload on Customs and Bor... more ... alarms, thereby improving border security as well as reducing the workload on Customs and Border Patrol agents ... UGS-BASED HUMAN/ANIMAL CLASSIFICATION PROBLEM ... background mean subtraction in order to normalize the data, following which the data is divided into 3 ...

Research paper thumbnail of Investigation of novel spectral and wavelet statistics for UGS-based intrusion detection

Unattended Ground, Sea, and Air Sensor Technologies and Applications XIV, 2012

Research paper thumbnail of Investigation of kinematic features for dismount detection and tracking

Signal and Data Processing of Small Targets 2012, 2012

Research paper thumbnail of SUMATRA: Supervised Modeling of ATR Algorithms

Proceedings of the IEEE 2010 National Aerospace & Electronics Conference, 2010

... Design of the man-machine interface for an automatic cuer system. IEEE 1992. [4] Rajagopal, A... more ... Design of the man-machine interface for an automatic cuer system. IEEE 1992. [4] Rajagopal, A., Garwal, S., Ramakrishnan, S. (2005). ... Proceedings of the 34th Applied Imagery and Pattern Recognition Workshop. [6] Ravichandran, B. Gandhe, A. Smith, R. Mehra, R. (2007). ...

Research paper thumbnail of <title>Discrimination and tracking of dismounts using low-resolution aerial video sequences</title>

Signal and Data Processing of Small Targets 2011, 2011

Research paper thumbnail of A parametric interpolator with confined chord errors, acceleration and deceleration for NC machining

Computer-aided Design, 2003

Parametric interpolation has many advantages over linear interpolation in machining curves. Real ... more Parametric interpolation has many advantages over linear interpolation in machining curves. Real time parametric interpolation research so far has addressed achieving a uniform feed rate, confined chord errors and jerk limited trajectory planning. However, simultaneous consideration of confined chord errors that respect the acceleration and deceleration capabilities of the machine has not been attempted. In this paper, the offline detection of feed rate sensitive corners is proposed. The velocity profile in these zones is planned so that chord errors are satisfied while simultaneously accommodating the machine's acceleration and deceleration limits. Outside the zone of the feed rate sensitive corners, the feed rate is planned using the Taylor approximation. Simulation results indicate that the offline detection of feed rate sensitive corners improves parametric interpolation. For real time interpolation, the parametric curve information can be augmented with the detected feed rate sensitive corners that are stored in 2 £ 2 matrices. q

Research paper thumbnail of Setup reduction in printed circuit board assembly by efficient sequencing

International Journal of Advanced Manufacturing Technology, 2005

Component setup time in printed circuit board (PCB) assembly makes up a significant part of the t... more Component setup time in printed circuit board (PCB) assembly makes up a significant part of the total production time in PCB manufacturing. The sequence in which PCBs are assembled is one of the fundamental factors determining the number of component switches that are needed. group technology techniques have been used to group PCB boards into similar groups to determine the assembly sequence. The measure of similarity is the key to the grouping problem. In PCB assembly, the similarity must be considered not only amongst different PCBs but must also taking into account the varying contents of the feeder rack on which the components are mounted in an incremental mode. In this paper, a new grouping strategy that combines the feeder rack contents into the similarity measure for efficient grouping is proposed. The groups of PCBs are then sequenced efficiently using a heuristic that resembles greedy tree traversal. The new grouping and group sequencing strategy outperforms existing methods of grouping particularly for large PCB component incidence matrices.

Research paper thumbnail of Yield improvement in wafer planarization: Modeling and simulation

Journal of Manufacturing Systems, 2003

Chemical mechanical polishing (CMP) is a planarization process that produces high-quality surface... more Chemical mechanical polishing (CMP) is a planarization process that produces high-quality surfaces both locally and globally. CMP is one of the key process steps during the fabrication of very large scale integrated (VLSI) chips in integrated circuit manufacturing. CMP consists of a chemical process and a mechanical process being performed together to reduce height variation across a wafer. High and reliable wafer yield, which is dependent on uniformity of the material removal rate across the entire wafer, is of critical importance in the CMP process. In this paper, the variations in the material removal rate across the wafer are analytically modeled assuming a rigid wafer and a flexible polishing pad. The wafer pad contact is modeled as the indentation of a rigid indenter on an elastic half-space. The model predictions are first verified against experimental observations. Simulation results for wafer yield under open-loop processing conditions are presented. Wafer curvature is identified as a key design variable influencing the spatial distribution of the material removal rate. The proposed model can be applied to control wafer-scale material removal rate variations in a CMP process.

Research paper thumbnail of NC Machining of Freeform Pockets with Arbitrary Wall Geometry Using a Grid-Based Navigation Approach

International Journal of Advanced Manufacturing Technology, 2001

A tool path must be determined in an efficient manner to generate NC (numerical control) code for... more A tool path must be determined in an efficient manner to generate NC (numerical control) code for machining. This is particularly important when machining freeform pockets with arbitrary wall geometry on a three-axis CNC machine. In this paper, a grid-based D navigation algorithm for generating NC tool-path data for both linear interpolation and a combination of linear and circular interpolation is presented for three-axis CNC milling of general pockets with sculptured bottom surfaces. The pocket surface is discretised by defining a grid and the navigation algorithm plans the tool motion. The grid size and the cutter diameter are chosen so that a predefined tolerance for surface roughness is satisfied. The grid-based navigation algorithm is simulated graphically and verified experimentally.

Research paper thumbnail of Tool wear monitoring in ramp cuts in end milling using the wavelet transform

International Journal of Advanced Manufacturing Technology, 2004

Tool wear identification and estimation present a fundamental problem in machining. With tool wea... more Tool wear identification and estimation present a fundamental problem in machining. With tool wear there is an increase in cutting forces, which leads to a deterioration in process stability, part accuracy and surface finish. In this paper, cutting force trends and tool wear effects in ramp cut machining are observed experimentally as machining progresses. In ramp cuts, the depth of cut is continuously changing. Cutting forces are compared with cutting forces obtained from a progressively worn tool as a result of machining. A wavelet transform is used for signal processing and is found to be useful for observing the resultant cutting force trends. The root mean square (RMS) value of the wavelet transformed signal and linear regression are used for tool wear estimation. Tool wear is also estimated by measuring the resulting slot thickness on a coordinate measuring machine.

Research paper thumbnail of Multiresolution offsetting and loose convex hull clipping for 2.5D NC machining

Computer-aided Design, 2004

A complex curve can be decomposed using wavelet-based multiresolution analysis into lower resolut... more A complex curve can be decomposed using wavelet-based multiresolution analysis into lower resolution curves. In this paper B-spline wavelet theory is applied to NC machining of contoured 2D objects. High-resolution curves are used close to the object boundary, while lower resolution curves are used farther away from the object boundary. This reduces tool path length and sharp corners are smoothed out thereby reducing uncut areas. The wavelet curves are clipped against a loose convex hull of the 2D object contour to further improve the efficiency of the generated tool paths. Simulation results indicate that the wavelet based tool paths and clipping improves machining efficiency. q

Research paper thumbnail of Multiresolution analysis as an approach for tool path planning in NC machining

Computer-aided Design, 2003

This paper investigates new wavelet-based multiresolution modeling techniques in CAD. Models in t... more This paper investigates new wavelet-based multiresolution modeling techniques in CAD. Models in the system are represented by endpoint-interpolating B-spline functions. Wavelet deformation techniques are extended to include synthesis editing and detail blending from previous sweep editing and fractional editing methods. Application of multiresolution editing to multiple patches of complex topology is investigated. An algorithm for multi-patch deformation is developed by

Research paper thumbnail of iDiver: underwater text messaging and locating system for divers

Ocean Sensing and Monitoring IV, 2012

Research paper thumbnail of Sensor fusion and feature-based human/animal classification for Unattended Ground Sensors

2010 IEEE International Conference on Technologies for Homeland Security (HST), 2010

... alarms, thereby improving border security as well as reducing the workload on Customs and Bor... more ... alarms, thereby improving border security as well as reducing the workload on Customs and Border Patrol agents ... UGS-BASED HUMAN/ANIMAL CLASSIFICATION PROBLEM ... background mean subtraction in order to normalize the data, following which the data is divided into 3 ...

Research paper thumbnail of Investigation of novel spectral and wavelet statistics for UGS-based intrusion detection

Unattended Ground, Sea, and Air Sensor Technologies and Applications XIV, 2012

Research paper thumbnail of Investigation of kinematic features for dismount detection and tracking

Signal and Data Processing of Small Targets 2012, 2012

Research paper thumbnail of SUMATRA: Supervised Modeling of ATR Algorithms

Proceedings of the IEEE 2010 National Aerospace & Electronics Conference, 2010

... Design of the man-machine interface for an automatic cuer system. IEEE 1992. [4] Rajagopal, A... more ... Design of the man-machine interface for an automatic cuer system. IEEE 1992. [4] Rajagopal, A., Garwal, S., Ramakrishnan, S. (2005). ... Proceedings of the 34th Applied Imagery and Pattern Recognition Workshop. [6] Ravichandran, B. Gandhe, A. Smith, R. Mehra, R. (2007). ...

Research paper thumbnail of <title>Discrimination and tracking of dismounts using low-resolution aerial video sequences</title>

Signal and Data Processing of Small Targets 2011, 2011

Research paper thumbnail of A parametric interpolator with confined chord errors, acceleration and deceleration for NC machining

Computer-aided Design, 2003

Parametric interpolation has many advantages over linear interpolation in machining curves. Real ... more Parametric interpolation has many advantages over linear interpolation in machining curves. Real time parametric interpolation research so far has addressed achieving a uniform feed rate, confined chord errors and jerk limited trajectory planning. However, simultaneous consideration of confined chord errors that respect the acceleration and deceleration capabilities of the machine has not been attempted. In this paper, the offline detection of feed rate sensitive corners is proposed. The velocity profile in these zones is planned so that chord errors are satisfied while simultaneously accommodating the machine's acceleration and deceleration limits. Outside the zone of the feed rate sensitive corners, the feed rate is planned using the Taylor approximation. Simulation results indicate that the offline detection of feed rate sensitive corners improves parametric interpolation. For real time interpolation, the parametric curve information can be augmented with the detected feed rate sensitive corners that are stored in 2 £ 2 matrices. q

Research paper thumbnail of Setup reduction in printed circuit board assembly by efficient sequencing

International Journal of Advanced Manufacturing Technology, 2005

Component setup time in printed circuit board (PCB) assembly makes up a significant part of the t... more Component setup time in printed circuit board (PCB) assembly makes up a significant part of the total production time in PCB manufacturing. The sequence in which PCBs are assembled is one of the fundamental factors determining the number of component switches that are needed. group technology techniques have been used to group PCB boards into similar groups to determine the assembly sequence. The measure of similarity is the key to the grouping problem. In PCB assembly, the similarity must be considered not only amongst different PCBs but must also taking into account the varying contents of the feeder rack on which the components are mounted in an incremental mode. In this paper, a new grouping strategy that combines the feeder rack contents into the similarity measure for efficient grouping is proposed. The groups of PCBs are then sequenced efficiently using a heuristic that resembles greedy tree traversal. The new grouping and group sequencing strategy outperforms existing methods of grouping particularly for large PCB component incidence matrices.

Research paper thumbnail of Yield improvement in wafer planarization: Modeling and simulation

Journal of Manufacturing Systems, 2003

Chemical mechanical polishing (CMP) is a planarization process that produces high-quality surface... more Chemical mechanical polishing (CMP) is a planarization process that produces high-quality surfaces both locally and globally. CMP is one of the key process steps during the fabrication of very large scale integrated (VLSI) chips in integrated circuit manufacturing. CMP consists of a chemical process and a mechanical process being performed together to reduce height variation across a wafer. High and reliable wafer yield, which is dependent on uniformity of the material removal rate across the entire wafer, is of critical importance in the CMP process. In this paper, the variations in the material removal rate across the wafer are analytically modeled assuming a rigid wafer and a flexible polishing pad. The wafer pad contact is modeled as the indentation of a rigid indenter on an elastic half-space. The model predictions are first verified against experimental observations. Simulation results for wafer yield under open-loop processing conditions are presented. Wafer curvature is identified as a key design variable influencing the spatial distribution of the material removal rate. The proposed model can be applied to control wafer-scale material removal rate variations in a CMP process.

Research paper thumbnail of NC Machining of Freeform Pockets with Arbitrary Wall Geometry Using a Grid-Based Navigation Approach

International Journal of Advanced Manufacturing Technology, 2001

A tool path must be determined in an efficient manner to generate NC (numerical control) code for... more A tool path must be determined in an efficient manner to generate NC (numerical control) code for machining. This is particularly important when machining freeform pockets with arbitrary wall geometry on a three-axis CNC machine. In this paper, a grid-based D navigation algorithm for generating NC tool-path data for both linear interpolation and a combination of linear and circular interpolation is presented for three-axis CNC milling of general pockets with sculptured bottom surfaces. The pocket surface is discretised by defining a grid and the navigation algorithm plans the tool motion. The grid size and the cutter diameter are chosen so that a predefined tolerance for surface roughness is satisfied. The grid-based navigation algorithm is simulated graphically and verified experimentally.

Research paper thumbnail of Tool wear monitoring in ramp cuts in end milling using the wavelet transform

International Journal of Advanced Manufacturing Technology, 2004

Tool wear identification and estimation present a fundamental problem in machining. With tool wea... more Tool wear identification and estimation present a fundamental problem in machining. With tool wear there is an increase in cutting forces, which leads to a deterioration in process stability, part accuracy and surface finish. In this paper, cutting force trends and tool wear effects in ramp cut machining are observed experimentally as machining progresses. In ramp cuts, the depth of cut is continuously changing. Cutting forces are compared with cutting forces obtained from a progressively worn tool as a result of machining. A wavelet transform is used for signal processing and is found to be useful for observing the resultant cutting force trends. The root mean square (RMS) value of the wavelet transformed signal and linear regression are used for tool wear estimation. Tool wear is also estimated by measuring the resulting slot thickness on a coordinate measuring machine.

Research paper thumbnail of Multiresolution offsetting and loose convex hull clipping for 2.5D NC machining

Computer-aided Design, 2004

A complex curve can be decomposed using wavelet-based multiresolution analysis into lower resolut... more A complex curve can be decomposed using wavelet-based multiresolution analysis into lower resolution curves. In this paper B-spline wavelet theory is applied to NC machining of contoured 2D objects. High-resolution curves are used close to the object boundary, while lower resolution curves are used farther away from the object boundary. This reduces tool path length and sharp corners are smoothed out thereby reducing uncut areas. The wavelet curves are clipped against a loose convex hull of the 2D object contour to further improve the efficiency of the generated tool paths. Simulation results indicate that the wavelet based tool paths and clipping improves machining efficiency. q

Research paper thumbnail of Multiresolution analysis as an approach for tool path planning in NC machining

Computer-aided Design, 2003

This paper investigates new wavelet-based multiresolution modeling techniques in CAD. Models in t... more This paper investigates new wavelet-based multiresolution modeling techniques in CAD. Models in the system are represented by endpoint-interpolating B-spline functions. Wavelet deformation techniques are extended to include synthesis editing and detail blending from previous sweep editing and fractional editing methods. Application of multiresolution editing to multiple patches of complex topology is investigated. An algorithm for multi-patch deformation is developed by