Vol. 7 & Issue 4 ; Section C : Physical Sciences

Date : Aug. to Oct.2017

 

Investigation and Mitigation of Power Quality Events in Distribution System

Chetan E. Morkhade and Chetan M. Bobade

JCBPS; Section C; August 2017 – October 2017, Vol. 7, No. 4; 801-808

[DOI: 10.24214/jcbps.C.7.4.80108.]

  • Abstract

    The investigation and mitigation of power quality events in power systems are important work in monitoring and protection of power system network. Most of the power system disturbances are non-stationary and transitory in nature and new tools are being used nowadays for the analysis of power quality disturbances. This paper presents a wavelet based feature extraction method for the detection of power quality problem. The disturbance waveforms obtained from simulation are decomposed by discrete wavelet transform. The custom power device DSTATCOM is used for the mitigation of power quality events. Voltage sag, Transient and under voltage have been tested and mitigated in PSCAD.

Radiation and Hall Effects on Unsteady Free MHD Convection Flow past a Vertical Porous Plate with Heat Absorption, Thermo Diffusion and Chemical Reaction in Slip Flow Regime

K.Balamurugan and V.Amuthavalli

JCBPS; Section C; August 2017 – October, 2017, Vol. 7, No. 4; 809-822,

[DOI: 10.24214/jcbps.C.7.4.80922]

  • Abstract

    The present paper deals with the analysis of unsteady free MHD convection heat and mass transfer flow of a viscous fluid through a vertical moving porous plate in slip flow regime with radiation, Hall Effect and heat absorption in presence of chemical reaction and thermo diffusion effect. Approximate solutions for velocity, temperature and concentration fields are obtained by solving the governing equations of the flow field using perturbation technique. The expressions for skin-friction, rate of heat transfer and rate of mass transfer are also derived. The effect of various parameters like Schmidt number(Sc), Prandtl number(Pr), Grashof number(Gr), Modified Grashof number(Gm), Magnetic parameter(M), Radiation parameter(F), Porosity parameter(K), Hall parameter(m), Heat absorption parameter(S), Chemical reaction parameter(R) and Soret effect(So) on velocity, temperature and concentration profiles are discussed with the help of numerical values and the graphs.

A theoretical study of super fluidity of an atomic Fermi gas near the unitary limit and evaluation of gap function as a function of K/KF in the unitary limit

Shivram nath Upadhay, Vijay Kumar Verma and L. K. Mishra

JCBPS; Section C; August 2017 – October, 2017, Vol. 7, No. 4; 823-841.

[DOI: 10.24214/jcbps.C.7.4.82341.]

  • Abstract

    Using the theoretical formalism of S.De Palo etal (Laser Phys. 15, 376 (2005)), we have theoretically studied super fluidity of an atomic Fermi gas near the unitarily limit. Our theoretically evaluated values of gap function Δ(k) as a function of k/kfor different values of  g /¯n/EF  show that the gap function has a damped oscillatory behaviour. Our theoretically valuated results of the ratio Δο/EF and μ/Eas a function of g/¯n/Eshow that Δο/Edecreases and μ/Eincreases as a function of g /¯n/EF  For large value of g /¯n/EF  Δο/Ebecomes constant while μ/EF  increases and becomes positive from negative values. These results also indicate that the resonance is along BEC side. Our theoretically evaluated results of Δο/KβTas a function T/ Tfor different values of g /¯n/Eindicate that the values decrease as T/ Tfor all values of g /¯n/E We observed that the narrow resonance favours occurrence of super fluidity. It is also observed that the smooth temperature behaviour is the manifestation of short ranged, bosonic character of the result. Using the theoretical formalism of Q. Chen [Phys. Rev. A86, 023610 (2012)], we have theoretically evaluated the super fluid transition temperature in a unitary atomic Fermi gas on a lattice. Our theoretically evaluated result of TC /6t  as a function of –U/6t  for different densities show that maximum TC occurs on the BEC side of unitary limit. We theoretically evaluated results of TC / Eas a function of  –U/6t for different densities which indicate that TC has a functional form Tα /– t2/ U Our theoretically evaluated result of TC / EF  as a function of n1/3 show that TC / EF  exhibits higher order nonlinear dependence of n1/3 The minimum value of TC is on BCS region. Our theoretically evaluated results are in good agreement with the other theoretical workers.These theoretical studies may be relevant for constructing a complete theoretical description of the crossover from BEC of composite bosons to BCS of Cooper pairs. Till today, we do not have very successful reliable theory for high TC-superconductors. It is our firm belief that BCS-BEC crossover physics can give some valuable insight into this direction.