Soheli Farhana

Walking Hexapod Robot in Disaster Recovery: Developing Algorithm for Terrain Negotiation and Navigation

The catastrophic cyclone Sidr that wrecked havoc Bangladesh in 2007, tsunami hit most of the countries of Asia around Indian ocean in 2004, Katrina hit Arkansas in 2005, and the terrorist attacks on the World Trade Centers in 2001 are clear indication that we are not prepared for disaster recovery at all. In all cases the infrastructure could not withstand the fury of nature, even in the case of WTC the NYPD was not prepared for such gigantic task of rescue mission. The conventional reaction to such disaster is not adequate; a new paradigm shift is needed to address such calamities utilizing all resources at hand. Disaster recovery is defined to be the emergency response function which deals with the collapse of man made structures (G. Nejat, 2006). In any disaster either man made or due to Mother nature, the elementary tasks at hand are: (i) reach the affected hazardous field (ii) find and get information about victims, and (iii) rescue as many of them as possible. It is possible for robot to reach any hazardous field unlike who have limited mobility in such missions. Nowadays legged and wheeled robots are involved in such mission (Habib, 2000), (Y. Mori, 2005), (Rizo J, 2003), (Y. Baudoin, 1999). In terms of hazardous field navigation for disaster recovery mission, legged robots have advantages over wheeled robots. Wheeled robots are the simplest and cheapest and tracked robots are very good for moving, but not over almost all kinds of terrain. Manned wheeled vehicles (Habib, 2000), (Y. Mori, 2005) or robotic systems (Rizo J, 2003), (Y. Baudoin, 1999), have already been tested. Navigate over obstacles and ditches and even on stairs one of the foremost advantages legged robots hold over their wheeled or tracked counterparts. It shows that legged robots can operate in both even and rough terrain. Some general-purpose robots were tested for this kind of application, nowadays specific prototypes having special features are being built and tested for specific mission. The TITAN VIII walking robot, a four-legged robot was developed as a general-purpose walking robot at the Tokyo Institute of Technology, Japan (Hirose S, 1998). COMET-I maybe the first legged robot purposefully developed for rescue missions. It is a six-legged robot developed at Chiba University, Japan, and incorporates different sensors and location systems (Nonami K, 2000), (Q.J. Huang, 2003). This robot weighs about 120 kg. The Chiba University group has developed the fourth version of this 22

Analysis of CNT electronics structure to design CNTFET

In this paper, graphene electronic structure of carbon nanotubes has been analyzed and validate with past theoretical and experimental results. The energy dispersion relation, effective mass and intrinsic carrier concentration of graphene have been analyzed to build diverse carbon nanotubes. The electronics properties of graphene are subject to change with the different diameters and wrapping angles of carbon nanotubes. Different chiral vector (n, m) of a graphene allows to design carbon nanotube for a wide range of applications, which can be achieved from the analyzed carrier concentration calculation. The proposed calculations set a higher boundary for a wide range of applications including the integration of carbon nanotube internal architecture and carbon nanotube field effect transistors.

Modeling of small band-gap CNT for designing of faster switching CNTFET

This paper suggests the modeling phenomena of small band-gap Carbon Nanotube (CNT). Device physics of CNT is studied and do the calculation of sub-band for zigzag CNT to model small band-gap tubes. Each carbon nanotube is described as a graphene sheet rolled into a cylindrical shape so that the structure is one dimensional with axial symmetry. A comparison is made with the current literature to show that the proposed chirality CNT with small band-gap which makes faster switching Carbon Nanotube Field Effect Transistor (CNTFET).

Modeling of optimum chiral carbon nanotube using DFT

The geometrical structure of carbon nanotubes has been calculated and analyzed in this paper. The analysis of carbon nanotube for Pz orbital, perpendicular to the graphene sheet and thus the nanotube surface forms a delocalized π network across the nanotube, which is responsible for its electronic properties. These electronic properties are obtained from tight binding (TB) model for graphene. Furthermore, optimized DFT calculation shows the optimum chiral of CNT, which is semiconducting zigzag for SWCNT and MWCNT.

Design and Development of a Simulator for Modelling Carbon Nanotube

In this paper, a Matlab simulator is developed for modelling of carbon Nanotubes (CNTs). First electronics structure is derived and discussed to facilitate the analysis and modelling of the simulator. Then a calculation is done for electron energy dispersion relations for single-wall zigzag CNTs with different tube indexes. From the analysis of energy dispersion relation, it is derived an analytical models for CNT parameters such as the mobility and the intrinsic carrier concentration. Once obtain the CNT parameters, and then import them to the developed simulator. The simulator is based on the semiconductor equations and quantum effects. Finally the simulator produces the result for optimum modelling of CNT for electronic device application.

High frequency small signal modeling of CNTFET

In this paper, we describe the development of small signal model of a CNTFET. The development consist of high frequency response of CNTFET. The CNTFET generates higher output rather than the conventional Si MOSFET. An SPICE model for enhancement mode Carbon nanotube transistor has been developed. The performance analysis of the CNTFET shows the desirable performance parameter in terms of 10 Thz frequency with 1.8 mS.

Design of a current comparator for quaternary multi valued Analog to Digital Converter

A low-power quaternary comparator circuit using current-mode CMOS multiple-valued logic (MVL) circuits has been presented in this paper. Existing MVL comparator circuits consume high power. The circuit presented in this paper has been shown low power digital output. It has been simulated with PSPICE using the transistor model parameter values of the BSIM3 NMOS model V3.2 for 0.13 μm CMOS process. With a 1.3-volt power supply, simulations show that the proposed quaternary comparator consumes 0.107 mW total average static power and a sampling rate 500MHz. Power and speed for comparators designed in these technologies are discussed. The comparator design is suitable for the needs of mixed-signal integrated circuit design and can be implemented as a conversion circuit for systems based on multiple-valued logic design.

A collaborative navigation algorithm for multi-agent robots in autonomous reconnaissance mission

Robots are playing an increasingly more important role as the technology is maturing. Robots are omnipresent; numerous robots committed to a single task will become ordinary. Multi-agent robots are capable of handling problems in many different ways than individuals while achieving higher levels of performance. But present unique challenges for developing collaborative navigation algorithm and coordination among themselves are not sufficient for autonomous collaborative tasks. Some research papers based on collaborative robots have been reviewed in this paper; from review analysis we have developed an algorithm with behavioral based distributed knowledge of multi-agents for accomplishing collaborative navigation. The goal of multi-agent robots is to move as a cohesive team by sharing their distributed learning behaviors and navigating in autonomous reconnaissance missions. Finally some preliminary experimental results will be presented of the developed collaborative navigation algorithm between robots to reach the target and achieve their goal sharing their knowledge.

MEMS switch for designing a multi-band reconfigurable antenna

In this work, two adjacent patches and MEMS switches are proposed a reconfigurable antenna that is capable of operating at several frequencies. Optimization of wing patches is done to obtain more than three resonant frequencies of the antenna by selecting the MEMS cantilever bridge materials. The study shows that the material of MEMS switches has influenced the performance of the antenna. SiN as MEMS bridge material makes the antenna to operate at 16.76 GHz, 23.56 GHz and 27.7 GHz in the ldquoOFFrdquo and operate at 20.9 GHz and 21.91 GHz in the ldquoONrdquo states of MEMS switches. A comparative study has done for Alumina, SiN, GaAs and Teflon as MEMS bridge materials. The design is performed by using 3D electromagnetic simulator HFSS considering ideal MEMS switches.

Novel carbon nanotube model for low energy loss field-effect transistor

Abstract Carbon nanotube (CNT) shows excellent and novel performances in the field of electrical engineering. The electrical properties of CNT consist of exceptional behaviour that will help to manufacture very tiny semiconductor device. However, due to the lack of research, CNT is still competing with the silicon material in the semiconductor industry. In this research, a single walled CNT wrapping diameter of 1.95 nm is proposed such a way that it performs low energy consumption while it is acting as a channel material of a field-effect transistor. A set of electrical properties of CNT is analyzed to propose a novel model of the nanotube that exhibits low energy consumption compare to other electronics devices. Finally the CNT has been replaced with the silicon in the channel of a field-effect transistor that shows low energy consumption.