232 research outputs found
Planktonic Biodiversity of Bhoj Wetland, Bhopal, India
Biodiversity found on Earth today consists of many millions of distinct
biological species, which is the product of nearly 3.5 billion years of
evolution. This article deals with planktonic distribution of Bhoj
Wetland, Bhopal, India . Bhoj Wetland comprises of two lakes i.e. Upper
and Lower lakes of Bhopal. The Upper lake is shallow, highly stratified
and oligotrophic lake while Lower lake is eutrophic lake. Samples were
collected from Upper lake at two sampling stations and in Lower lakes
from three sampling stations with their reference stations. The work
was carried out for a period of two year (i.e. 2005-2006) in these
contrasting lakes @ JASE
Raman scattering in high temperature superconductors : An integrated view
The common features in the Raman data of high temperature superconductors:
(the cuprates, bismathates, alkali doped fullerides and some organic
superconductors), are analyzed. It was shown that qualitative understanding of
the data can be achieved in terms of non-Fermi liquid models for their normal
state, with appropiate bag mechanisms for the superconducting state.Comment: To appear in Physica B (1996). Invited talk presented by S. N.
Behera, Latex file in revtex style, six figures available on request to first
author (e-mail : [email protected]
Thermal effect on the optical and morphological properties of TiO2 thin films obtained by annealing Ti metal layer
Titanium metal layers of different thicknesses were deposited on optical glass, quartz and ceramic substrates at 50°C and 150°C substrate temperature with the help of magnetron deposition. Metal layers were converted into rutile phase of TiO2 at different annealing temperatures. The effect of thermal annealing on the morphology and refractive index of the thin film was investigated
Interplay of spin density wave and superconductivity with different pairing symmetry
A model study for the coexistence of the spin density wave and
superconductivity is presented. With reference to the recent angle resolved
photo emmission experimental data in high T_c cuprates, presence of the nested
pieces of bands is assumed. The single band Hubbard model, therefore, when
treated within the Hatree-Fock mean field theory leads to a spin density wave
(SDW) ground state. The superconductivity (SC) is assumed to be due to a
generalised attractive potential with a separable form without specifying to
any particular origin. It therefore allows a comparative study of the
coexistence of superconductivity of different order parameter symmetry with the
spin density wave state. We find that the phase diagram, comprising of the
amplitudes of the respective gaps (SC and SDW) Vs. band filling resembles to
that of the high T_c cuprates only when the order parameter of the
superconducting phase has d-wave symmetry. Thermal variation of different order
parameters (e.g, SC and SDW) also show interesting coexistence and reentrance
behaviors that are consistent with experimental observations, specially for the
borocarbides.Comment: 8 pages, 6 figures (postscript attached), Physica C (in press
Analytical modeling of synchronous demodulation of a multi-DOF gyro-accelerometer
This paper reports a analytical model of a 4-DOF gyro-accelerometer consisting of 2-DOF drive and 2-DOF sense oscillators configured orthogonally. A detection scheme for time varying angular rate and linear acceleration, by combining the structural-model of gyro-accelerometer with the processes of synchronous demodulation and filtration, has also been spelt out to investigate frequency responses at the event of angular motion and linear acceleration. Finally, the results of the model have been validated by comparing with MATLAB®/Simulink data which shows excellent matching with each other
Design and simulation of a SOI based mems differential accelerometer
In this paper, the design and analysis of a differential MEMS capacitive accelerometer is presented. The device is designed to be compatible for SOI based fabrication process. The outstanding mechanical and electrical properties of silicon on insulator (SOI) wafers make it popular for high-performance MEMS sensors such as accelerometers. The operating range of the designed device is 0-10g with its sense axis in the in-plane direction. The movable comb fingers attached to the proof mass form capacitors with the fixed electrode fingers. The movable and fixed fingers are spaced with unequal gaps to form the differential capacitive sensing configuration. The base capacitance of this configuration is about 0.77pF and the sensitivity in response to acceleration input is about 0.776 fF/g. The resonance frequency of the structure in the sensing mode is found to be 7.138 kHz.The work was partially funded by the Russian Federation Ministry of Education and Science
UV-LIGA fabrication process for realization of metal based MEMS gyroscope
This paper reports the complete fabrication process flow based on UV-LIGA technology for realization of metal based MEMS gyroscope. In this process, nickel is used as the structural layer and copper as the sacrificial layer. The economical three mask process has been optimized and the detailed step by step procedure for carrying out the fabrication is presented. The fabrication results after each process step have been presented and discussed. Scanning electron micrograph images of the released prototype gyroscope devices have been presented to demonstrate the successful fabrication of the prototypes
Design, simulation and fabrication process of a SOI based 2-DOF vibratory gyroscope
This paper reports the design, simulation and fabrication process for a 2-DOF decoupled vibratory gyroscope. The structure is deliberately designed to have decoupled drive and sense mode oscillation to prevent unstable operation due to mechanical coupling, resulting in low zero rate out-put drift. At the same time, the closer the drive and sense resonances are, the higher is the angular rate resolution of the gyroscope. This can be achieved by using symmetric suspensions, but it results in reduced bandwidth. The proposed design has been configured to achieve about 150 Hz bandwidth, while ensuring decoupled operation of the drive and sense modes. Fem analysis has been carried out in CoventorWare® MEMS DESIGN software and simulation results show that the drive resonance occurs at 21.48 kHz and sense resonance at 21.63 kHz. The structure is designed for 15 µm this device layer. Fabrication of the design is proposed using DRIE and sacrificial release etching on SOI wafer. DRIE etching with high aspect ratio has been successfully carried out as desired and the results have been presented
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