Showing papers in "Journal of the Indian Institute of Science in 2002"

Prediction-based location management using multilayer neural networks

Abstract: Location Management is one of the key issues in mobile networks to provide an efficient and low cost services. In this paper, we propose a prediction based location management scheme for locating a Mobile Host (MH), which depends on its history of movement pattern. A Multi-layer Neural Network (MNN) model for mobile movement prediction is designed to predict the future movement of a mobile host. The MNNs are trained with respect to the data obtained from the movement pattern of a mobile host for making predictions. The performance of the method has been verified for prediction accuracy by considering different movement patterns of a mobile host. The simulation results are presented and achieved up to an average of 93% prediction accuracy for uniform movement, 40% to 70% for regular movement and 2% to 30% for random movement patterns of a MH.

Novel applications of micro-shock waves in biological sciences

Abstract: Spherical micro-shock wave.s of a few mm radii can be generated both in ambient air and in water by expending a small amount of energy. Various techniques such as focusing of laser beam. energy deposition using electrical discharge In water. micro-explosion of silver aZide pellets and simultaneous actuation of piezo-ceramic/electrical crystal array can be used for creating micro-shock waves of requisite intensity. The nonlinear instantaneous pressure spike (MPa -100 MPa) generated by the micro-shock waves can be used in applications such as panicle delivery systems for gene therapy. food preservation. wood preservation and conditioning. and also in cancer treatment. The visualization studies of micro-shock waves generated using laser beam focusing in ambient air various types of micro-shock wave generators, the status of current research on various applications along with some experimental results on micro-shock wave asisted particle delivery systems are discussed in this paper.

Identification ofunstable transfer model with a zero by optimization method

Abstract: A method is proposed for closed identification of an unstable first-order plus time delay with a zero trainsfer function model using the step response of a PI or PID-controlled system. A standard optimization method is used to estimate the model parameters to match the closed loop response of the model with that of the actual response. A simple method is proposed for initial guesses of the transfer function model parameters (time delay, time constant, gain and the value of zero). The method is applied to unstable transfer function models with a positive or negative zero, and to a CSTR to identify an unstable FOPTD (first-order plus time delay) with a zero. It gives good resulst in all the simulation case studies considered. The effect of measurement noise and controller settings on the identification of transfer function model is studied.

DNA-amine interactions: from monolayers to nanoparticles

Abstract: DNA is a polyanionic molecule that can electrostatically interact with positively charged ligands. Interaction with surfactants such as CTAB leads to cooperative binding of detergent molecules through synergistic effects of electrostatic and hydrophobic forces. DNA can also form a monolayer at air-water interface with positively charged octylamine and nanoparticles with cationic lysine capped gold nanoparticles. Formation of such electrostatic composites of DNA has practical implications for developing DNA diagnostic systems and for lipidencapsulated DNA delivery systems.

A PWM scheme for a 3-level inverter cascading two 2-level inverters

Abstract: This paper shows that 3-level inversion can be achieved by connecting two 2-level inverters in cascade. Two isolated power supplies with DC link voltages are required for the proposed circuit topology. The voltages constitute half of that of a conventional 3-level inverter topology. Neutral point fluctuation is absent in the proposed scheme when compared to conventional neutral point clamped 3-level inverter. A sine-triangle-based PWM scheme is presented for the proposed topology.

Benzimidazoles withbiphenyls: Synthesis of 5- substituted - 2- n- propyl-1- [(2' - carboxybiphenyl-4-yl-) methyl] benzimidazoles

Abstract: A one-step coupling of substituted benzimidazoles with biphenylcarboxylic moiety mediated by potassium carbonate is described. The biphenylcarboxylic moiety was prepared from 9-H-fluorenone and substituted benzimidazoles were synthesized from o-phenylenediamine and butyric acid. Keywords: Benzimidazoles,The inherent dominating features of the structure of the Devanagari script have been used to accurately calculate the skew of the Devanagari word.

Thermochromic liquid crystals for assessing the performance of scramjet inlets with notched cowls

Abstract: Broadband thermochromic liquid crystals have been used to investigate the heat-transfer properties of geometries characteristic of scramjet inlets in a Mach 3 flow. The models tested comprised opposing 17O wedges that generate colliding shocks that can interact with boundary layers formed on an end wall. In one case, the end wall had a straight leading edge and in the other the leading edge was notched. The results indicate that heat-transfer rates and inlet separation can be reduced by using a notched cowl.

Chemical kinetics studies at high temperatures using shock tubes

Abstract: Shock tube is an unique facility to create temperature gradients exceeding million degrees Kelvin per second. We have established two shock tubes for measuring the kinetic reaction rates at high temperatures with two different but complementary detection techniques. The first one is a single pulse shock tube, in which the reflected shock is used to heat the molecules. The equilibrated products are analyzed by gas chromatograph and infrared spectrometer. The second one uses laser-schlieren system for online monitoring of the chemical reactions behind primary shock wave. The details of the shock tubes and some typical results obtained are presented in this paper.