Arnab Dhabal

Department of Astronomy
University of Maryland

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Major Projects

Jugnu Nanosatellite Mission

A 3-kg satellite of dimensions 30mm x 10mm x 10mm, with most advanced features of a normal satellite like a two-way communication system, a sophisticated Attitude Determination and Control System using Torquer Coils and Reaction Wheels, sustained power supply using solar panels, and payloads like Imaging, GPS and IMU, with an able On-Board Computer to control everything. The ejection system for the satellite was also designed indigenously. The team comprised undergraduate and graduate students from IIT Kanpur, led by Shantanu Agarwal and Prof. N. S. Vyas.

I was involved in the GPS subsystem of the satellite along with Siddharth Paliwal for three years. We designed the PCB on which the programmable GPS daughter board could be mounted. The system also consisted of a customized Patch Antenna for acquiring the signals. The board was programmed to take into account the high velocity of the satellite (8 km/s). Thorough ground testing and Simulator testing at ISRO Satellite Centre (ISAC) confirmed its functionability.

On 12th October, 2011, Jugnu was ejected into the Megha-Tropiques Orbit at 800 km altitude by a PSLV C-18 rocket launched from Sriharikota. It was a proud moment for the entire team.

Videos of :
1) The Making
2) The Launch

Further details are available on the sites:-
Jugnu Home Page
Technical details

Dwarf Galaxy Detection

The Dwarf Galaxy problem stands in the way of the established dark matter distribution models. In a quest for more of such galaxies having high non-Baryonic content, I developed codes for processing the astronomical images from Canada-France-Hawaii telescope available at the CADC using IRAF and SExtractor. This was a part of the MITACS summer internship under James Taylor at University of Waterloo, which I am still working on for further improvements in the code. A recent development was comparison of multiple bands for improved filtering. The code is currently detecting dwarf galaxies very accurately.

Technical Write-up

Negative differential resistance in GaN nanowires

GaN nanowires were grown on Si substrate and were studied using field emission scanning electron microscopy (SEM), transmission electron microscopy (TEM) and selected area electron diffraction (SAED) pattern. Both straight and zig-zag nanowires were formed. These were then dispersed between two gold contacts and isolated nanowires were identified for current–voltage (I–V ) studies. Subsequently, the connection between the nanowires and the gold pads were established using focused ion/electron beam-induced chemical vapour deposition of Pt.

I-V measurements were carried out, and we repeatedly got a negative differential resistance for isolated zig-zag GaN nanowires with FEB Pt contact.

The results were published as a research paper in a journal.

Reversals in Rayleigh Bénard Convection

Rayleigh Benard convection involves heating a fluid sample from below and maintaining it at a lower temperature from above that drives a convective flow. The system is defined by three parameters – Rayleigh number, Prandtl number and the geometry (including the aspect ratio).
The original aim of the project was to determine (i) the role of geometry in flow reversals, (ii) the dependence of reversals on Rayleigh numbers and (iii) presence of higher Fourier modes of flow.

We designed and fabricated the apparatus for the experiment taking into account factors like expected time of reversal, uniform heating and cooling requirements, thermocouple placements etc. Thermocouples placed at regular intervals registering temperatures are used to detect the direction of flow, and to study other features of the flow like velocity, turnover time and higher Fourier modes.

Project Report

Molecules in Femtosecond Laser Pulses

Molecules in high vacuum ionized by ultra-short laser pulses using pump-probe techniques, are collected by an electron multiplier and transferred to an oscilloscope. From time of flight measurements, the ions produced can be determined, which gives a better insight to nuclear structures.

I was involved in writing a Visual C++ code to digitize the entire process using an Acqiris digitizer for real-time data analysis. The project was carried out in the Max Planck Institute of Nuclear Physics, Heidelberg, under the supervision of Priv. Doz. Dr. Robert Moshammer, and along with Dr. Siva Rama Krishnan.

Quantum States in Ultra Thin Films

Studied how Band gaps of semiconductors and certain metals can be used to set up quantum wells. Carried out Energy band analysis for some potential well configurations (Double finite).

Under the supervision of the same professor, I was also involved in analyzing the diffraction pattern produced when photoelectrons pass through a slit pattern of an angular device used in an Angle-Resolved Photoemission Spectrometer(ARPES). I also assisted MSc student Sanjay Mahatha with operating the ARPES, and its Low energy electron diffraction (LEED) facility to study surface crystalline order of a graphite sample.

Brief report

IMU-GPS Integration using Kalman Filtering techniques

GPS (Global Positioning System) signals cannot be used to determine position in areas where there is no/poor satellite coverage. In such situations, Inertial Measurement Units (IMU) which give acceleration and angular velocity values can be utilized and its data integrated to get the position at any instant, if the position at the starting instant is known.

My work focussed on combining these two forms of data. I built a common platform in Visual Basic to run multiple IMU and GPS devices simultaneously. It involved sound knowledge of UART communication protocols. Once developed, Masters student Azmir Rabian and I implemented Kalman filtering and run time visualization of roll, pitch and yaw of the body. We tested the same by driving a car around with all these devices in the car.

Course Projects

Double Pendulum - Report

Coronal Heating Problem - Project Report; Presentation

Finite Element Analysis of a flat discontinuous bar under tensile loading - Project Report

Fabrication and Characterization of a Schottky Diode - Project Report

4-Dial Combination Lock - Design; Report; Photo

Psychological Effects of War and Terrorism on Children - Term paper

 

Other Technical Activities

Gaming Console using Microcontrollers - Won the first prize in the Embedded Design contest at Techkriti 2009, an all-India technical competition.
Video

GSM Mobile Circuit Finder - Developed a circuit that could catch signals from GSM phones, amplify them and make them audible through earphones.
Report

Wall Climbing Bot - Designed a bot that could climb up vertical metallic walls for a competition in IIT Bombay-Techfest 2009, the largest technical festival of India.
Photo

Asteroid Shooting Game using Integrated Circuits - Won the fifth prize at an electronics contest during Techkriti 2008.
Video