K. Ramesh

Bio: K. Ramesh is an academic researcher from Indian Institute of Technology Madras. The author has contributed to research in topics: Photoelasticity & Stress intensity factor. The author has an hindex of 23, co-authored 125 publications receiving 1884 citations. Previous affiliations of K. Ramesh include Indian Institute of Technology Bombay & Indian Institutes of Technology.

Robust multidirectional smoothing of isoclinic parameter in digital photoelasticity

Abstract: In digital photoelasticity, one gets full-field information about the difference in principal stresses and their orientations by postprocessing the intensity data. Isoclinic data obtained using phase shifting techniques have inherent noise. The higher the external load, the higher the noise. Further, noise removal becomes complex if the isoclinic data has π-jumps, isotropic points, etc. Initially, the origin of the noise in isoclinic data obtained using phase shifting techniques is discussed. An explanation for the presence of excessive noise in a circular polariscope-based algorithm is provided. Three methods for noise removal of isoclinic data calculated using a plane polariscope are proposed using an outlier smoothing algorithm. The first two use quality and standard deviation measures to identify the noise-free pixel from each individual scan. The last method involves progressive multidirectional smoothing. The effectiveness of the proposed smoothing schemes is demonstrated using the benchmark problem of a circular disc under diametral compression. Multidirectional progressive smoothing is found to be effective in removing the noise at lower as well as at higher loads. Finally, this scheme is used to smooth isoclinic data in two other problems, one that has a π-jump and the other that has both an isotropic point and a π-jump.

Automatic ordering of isochromatic fringes - a new methodology

Abstract: The intensity variations in the isochromatic fringe field are significant and even minute variations can be recorded using the modern day CCD cameras. The sodium vapour source (589. 3 nm) used in general has upto 4% of another wavelength of 589. 6 nm. In view of this, the minimum intensity forming a fringe is affected and is significant at high density fringe zones. This aspect is used to identify sources and sinks in the fringe field and a new methodology for fringe ordering is proposed. It requires only one image to be processed and hence is equally applicable for static and dynamic problems.

Simulation of Error in Digital Photoelasticity by Jones Calculus

Abstract: The accuracy of parameter evaluation by automated photoelastic techniques depends on both their theoretical formulation and experimental procedure The sensitivity of techniques such as phase shifting and load stepping to error in optical misalignment and quarter-wave plate mismatch would be of interest A generic approach to simulation of error in digital photoelasticity is presented The simulation has showed how to associate the errors in the phase map to the misalignment of optical elements

Recent developments in brittle and quasi-brittle failure assessment of engineering materials by means of local approaches

Abstract: Brittle failure of components weakened by cracks or sharp and blunt V-notches is a topic of active and continuous research. It is attractive for all researchers who face the problem of fracture of materials under different loading conditions and deals with a large number of applications in different engineering fields, not only with the mechanical one. This topic is significant in all the cases where intrinsic defects of the material or geometrical discontinuities give rise to localized stress concentration which, in brittle materials, may generate a crack leading to catastrophic failure or to a shortening of the assessed structural life. Whereas cracks are viewed as unpleasant entities in most engineering materials, U- and V-notches of different acuities are sometimes deliberately introduced in design and manufacturing of structural components. Dealing with brittle failure of notched components and summarizing some recent experimental results reported in the literature, the main aim of the present contribution is to present a review of some local approaches applicable near stress raisers both sharp and blunt. The reviewed criteria allowed the present authors to develop a new approach based on the volume strain energy density (SED), which has been recently applied to assess the brittle failure of a large number of materials. The main features of the SED approach are outlined in the paper and its peculiarities and advantages accurately underlined. Some examples of applications are reported, as well. The present review is based on the authors’ experience over more than 15 years and the contents of their personal library. It is not a dispassionate literature survey.

Some Basic Problems Of The Mathematical Theory Of Elasticity

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Evidence for a protein transported through the secretory pathway en route to the higher plant chloroplast.

Abstract: In contrast to animal and fungal cells, green plant cells contain one or multiple chloroplasts, the organelle(s) in which photosynthetic reactions take place. Chloroplasts are believed to have originated from an endosymbiotic event and contain DNA that codes for some of their proteins. Most chloroplast proteins are encoded by the nuclear genome and imported with the help of sorting signals that are intrinsic parts of the polypeptides. Here, we show that a chloroplast-located protein in higher plants takes an alternative route through the secretory pathway, and becomes N-glycosylated before entering the chloroplast.

System for configuring a process control environment

Abstract: A control studio object system is disclosed which allows a process control environment to be easily and quickly configured or modified. The control studio object system includes a stencil portion having stencil items conforming to algorithms and a diagram portion to which the stencil items may be copied via a drag and drop operation. Because the stencil items are objects which contain all of the information required by a diagram portion to create an object that contains all of the information necessary to program the process control environment, the completed diagram portion reflects the actual configuration of the process control environment. Additionally, providing the stencil items as objects allows the diagrammed environment to be installed directly to nodes without requiring the diagram to be compiled or rewritten in a language conforming to the node.

Quality-guided phase unwrapping technique: comparison of quality maps and guiding strategies

Abstract: Quality-guided phase unwrapping is a widely used technique with different quality definitions and guiding strategies reported. It is thus necessary to do a detailed comparison of these approaches to choose the optimal quality map and guiding strategy. For quality maps, in the presence of noise, transform-based methods are found to be the best choice. However in the presence of discontinuities, phase unwrapping is itself unresolved and hence quality-guided phase unwrapping is not sufficient. For guiding strategies, classical, two-section, and stack-chain guiding strategies are chosen for comparison. If accuracy is the foremost criterion then the classical guiding strategy with a data structure of indexed interwoven linked list is best. If speed is of essence then the stack-chain guiding strategy is the one to use.