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Papers by pratibha verma
2021 IEEE International Midwest Symposium on Circuits and Systems (MWSCAS), 2021
This work investigates the idea of using electrical energy injection for nonlinear mechanical ene... more This work investigates the idea of using electrical energy injection for nonlinear mechanical energy harvesters (MEH). The system level analysis and device simulations suggest an improved performance can be obtained by selectively injecting an external signal. It further explores the possibility of using a hybrid MEH device combining piezoelectric and electromagnetic transducers to implement the proposed electrical energy injection method. The hybrid SECE technique is used to design the power management interface circuitry which also performs the energy injection. The designed circuits are simulated using CMOS 180 nm process and in region of multi-stability, it shows peak improvement in device output voltage around 6x time and in extracted power around 40-80x compared to conventional hybrid SECE energy harvesting technique.
IETE Journal of Research, 1969
Several approximate formulae, often used in practice, have been derived from the Appleton-Hartree... more Several approximate formulae, often used in practice, have been derived from the Appleton-Hartree formulae using the Bailey and Somerville (1938) approach. The absorption suffered by radio waves of a number of frequencies in model ionospheric layers have been computed using the various approximate formulae derived. Comparison of different absorption coefficients reveal that the errors which are caused by using some of the approximations lie within 10 per cent whereas in case of some others it may exceed 50 per cent.
Applied Scientific Research, Section B, 1962
An iniinitely long self-gravitating incompressible plasma cylinder is considered. Inside the cyli... more An iniinitely long self-gravitating incompressible plasma cylinder is considered. Inside the cylinder there is a uniform magnetic field B, parallel to its axis and outside there are magnetic fields Be parallel to the axis and Bo ro/r in the azimuthal direction. The surface currents arising due to the discontinuity in the magnetic fields across the surface are incorporated into the boundary conditions to derive a dispersion relation. The conclusions are: (a) The magnetic field configuration (Bi = Be = B0) has got a stabilizing effect for modesm = 0, 1 and 2, for modesm = 1 and 2 it keeps
Zeitschrift f�r Physik, 1965
The stability of a uniformly rotating cylindrical plasma configuration in dynamical equilibrium i... more The stability of a uniformly rotating cylindrical plasma configuration in dynamical equilibrium is discussed. Assuming an axial current and sheet currents for the plasma, we have obtained a dispersion relation for non-axisymmetric perturbations. The dispersion relation comes out to be a complex and implicit function of the frequency of perturbations. Here we have discussed the dispersion equation for the modem=1,
2021 IEEE International Midwest Symposium on Circuits and Systems (MWSCAS), 2021
This work investigates the idea of using electrical energy injection for nonlinear mechanical ene... more This work investigates the idea of using electrical energy injection for nonlinear mechanical energy harvesters (MEH). The system level analysis and device simulations suggest an improved performance can be obtained by selectively injecting an external signal. It further explores the possibility of using a hybrid MEH device combining piezoelectric and electromagnetic transducers to implement the proposed electrical energy injection method. The hybrid SECE technique is used to design the power management interface circuitry which also performs the energy injection. The designed circuits are simulated using CMOS 180 nm process and in region of multi-stability, it shows peak improvement in device output voltage around 6x time and in extracted power around 40-80x compared to conventional hybrid SECE energy harvesting technique.
IETE Journal of Research, 1969
Several approximate formulae, often used in practice, have been derived from the Appleton-Hartree... more Several approximate formulae, often used in practice, have been derived from the Appleton-Hartree formulae using the Bailey and Somerville (1938) approach. The absorption suffered by radio waves of a number of frequencies in model ionospheric layers have been computed using the various approximate formulae derived. Comparison of different absorption coefficients reveal that the errors which are caused by using some of the approximations lie within 10 per cent whereas in case of some others it may exceed 50 per cent.
Applied Scientific Research, Section B, 1962
An iniinitely long self-gravitating incompressible plasma cylinder is considered. Inside the cyli... more An iniinitely long self-gravitating incompressible plasma cylinder is considered. Inside the cylinder there is a uniform magnetic field B, parallel to its axis and outside there are magnetic fields Be parallel to the axis and Bo ro/r in the azimuthal direction. The surface currents arising due to the discontinuity in the magnetic fields across the surface are incorporated into the boundary conditions to derive a dispersion relation. The conclusions are: (a) The magnetic field configuration (Bi = Be = B0) has got a stabilizing effect for modesm = 0, 1 and 2, for modesm = 1 and 2 it keeps
Zeitschrift f�r Physik, 1965
The stability of a uniformly rotating cylindrical plasma configuration in dynamical equilibrium i... more The stability of a uniformly rotating cylindrical plasma configuration in dynamical equilibrium is discussed. Assuming an axial current and sheet currents for the plasma, we have obtained a dispersion relation for non-axisymmetric perturbations. The dispersion relation comes out to be a complex and implicit function of the frequency of perturbations. Here we have discussed the dispersion equation for the modem=1,