1. Design and Analysis of a scalable Concentrated Solar Power farm using lightweight heliostats, IEEE International Conference ICGCE-2013 , Chennai, India (Dec 2013).
A CSP farm design and analysis using light, servo-controllable, rectangular mirror arrays as heliostats is presented. Performance of such a heliostat for CSP is analyzed for diurnal and seasonal variations. The equations to program the heliostat for sun tracking are derived and the effect of shadowing on the heliostat efficiency is quantified. The optimal heliostat design process for a CSP farm is presented. A horizontal as well as vertical farm layout are discussed and compared. It is shown that a CSP farm based on the heliostat design presented here can be robust, low-cost, flexible and scalable.
2. Channel sounding and experimental verification of Time Reversal Mirror in an underwater tank facility, National Workshop UWASPCOM-2013, Bangalore, India (May, 2013).
Time reversal mirror (TRM) is an idea that has caught the imagination of underwater acoustic researchers and has been applied widely for sonar signaling and communication purposes. TRM as an algorithmic tool for signaling and processing of the received waveforms can help achieve enhanced signal to noise ratios as well as signal focus, both temporally and spatially. The ability of TRM to convert a highly dispersive channel in a reverberant environment to its advantage is rather unique. In this paper, we perform channel sounding studies to estimate the impulse response, and then experimentally verify the concept of TRM in an underwater tank facility.
3. Acoustic Vector Sensor array signal correlation modeling based on Normal-mode approach with application to underwater OFDM multichannel receiver, in Proc. International Conference UComms-2012, LaSpezia, Italy (May 2012).
An acoustic vector sensor (AVS) measures acoustic pressure and three orthogonal components of particle velocity at the same location, unlike the conventional scalar sensor which measures acoustic pressure alone. If an AVS receiver array is used in an underwater communication system the source has access to four channels of communication with each sensor in the array. The output of one of these channels is the acoustic pressure signal and the outputs of the other three channels are the three components of particle velocity signals. Thus an AVS receiver array provides greater diversity than a similar array of acoustic pressure sensors. In order to design a communication system that fully exploits this potential, it is necessary to characterize the signal correlations among different channels associated with an AVS array.
4. Characterization of a Tonpilz transducer and performance analysis for sound projection in underwater acoustic signaling applications, National Comsol Conf., 2011, Bangalore.
Underwater acoustic signals need transducers to generate and detect signals with high power, linearity, dynamic-range and beam-width. Among a variety of transducer designs, a Tonpilz transducer stands out for power and long-range applications. A Tonpilz transducer for underwater acoustic signaling is developed to scale and analyzed using FEM tools with Comsol. The underlying pressure-acoustics and piezoelectric phenomena are examined as a function of sizing, transducer dimensioning, materials, and variability. Using FEM tools, we analyze and evaluate key transducer performance specs such as resonant frequency, tunability, material-choices, beam-pattern and scalability. Using Comsol as a design tool, one can develop low-cost, reliable, miniature transducers for sonar signaling and ultrasonic scanners.
5. GMSK modulation for reverberation limited underwater acoustic Time Reversal mirror based communication, IEEE SYMPOL conference, Nov 2011, Cochin, India.
Time reversal mirror as a tool for spatio-temporal focusing is investigated for reverberation limited underwater acoustic communication. The dominant source of reverberation considered is from the ocean bottom. Link level simulations for signal and reverberation are performed to study BER characteristics using a ray-theoretic underwater channel propagation model. GMSK modulated signals employed with time-reversal mirror technique are shown to achieve significant improvement in BER and throughput. Newly realizable telemetry architectures are discussed.