• N Patel

      Articles written in Sadhana

    • Optoelectronics — past, present, and future

      C Kumar N Patel

      More Details Abstract Fulltext PDF

      Considerable progress has been made in the field of optoelectronics in the last thirty years. The two principal drivers for this progress have been the invention of the laser and low-loss optical fibres. But what is optoelectronics? Optoelectronics is more than just a marriage of electronics and optics. It represents the higher order integration of technical achievements in electronics and photonics to allow one to chose what, where, when, and how to address both old and new problems and opportunities for increasing customer satisfaction in the areas of information movement and management. I will review the progress in the field and share my insights into where the future lies. The important question no longer is if optics will replace electronics in many of the technologies underlying information movement and management; it is when and to what degree. The limitation no longer arises from the technical capabilities, it comes from economics and social values provided by the increased capabilities in communications and computers.

    • On numerical moment-curvature relationship of a beam


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      In complex bending problems involving material and geometric non-linearity, quite often moment curvature based approach is preferred over stress-strain based methods. For such an approach, available uniaxial stress-strain test data or models are required to be converted into moment-curvature relationship. The process of con-version of uniaxial stress-strain relationship into a moment-curvature relationship is non-unique. And hence, complete moment-curvature law can be modelled suiting any of the several hardening laws. Such modelling will be very important when abeam is under cyclic load producing reverse plastic deformation. In this paper, an approach is presented to obtain a unique moment-curvature relationship from any given stress-strain law. Standard elasto-plastic models viz.elastic-perfectly plastic, isotropic and kinematic hardening are considered to produce corresponding unique moment-curvature relationships. The results indicate that an isotropic curvature hardening model, corresponding to an elastic perfectly plastic stress-strain model, would be erroneous. Additionally, step by step procedure of using the approach in solving a large deflection elasto-plastic beam problem, is demonstrated here.

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