| || Some Mathematical Aspects of Spread and Stability of Time-Delay Gonorrhea
Author : Srinivas, N.C. ;Ramacharyulu, N. Ch. Pattabhi
Source : Defence Science Journal ; Vol:41(3) ; 1991 ; pp 277-293
Subject : 51 Mathematics
Keywords : Epidemic diseases ;Mathematical models;Medical science
Abstract : A mathematical model of time-delay gonorrhea among hetero and homosexuals is presented as a system of first order ordinary coupled integro-differential equations with delayed arguments. A theorem on the positivity of the solutions is proved to establish the feasibility of the proposed mode. Further, the only possible diseased equilibrium state has been identified and the stability analysis of such a state for some epidemiological possibilities has been carried out. It has been observed that the impulsive type inflow of infectives into the population maintained the stability of the diseased equilibrium state and is valid even for the exponential type inflows. In contrast to this, instability sets in when one or other of infective inflows is of the gate type.
| || Couttete Flow of a Dusty Incompressible Fluid with One of the Horizontal Moving Boundaries Suddenly Stopped
Author : Ramacharyulu, N. Ch. Pattabhi ;Prasad, V.V. Ramana
Source : Defence Science Journal ; Vol:31(3) ; 1981 ; pp 231-240
Subject : 532 Fluid Mechanics
Keywords : Relaxation time ;Slip velocity;Skin friction;Flux;Impulsive motion;Dusty fluid
Abstract : The unsteady flow of an incompressible viscous fluid with a uniform distribution of dust particles between two parallel plates when one of which is impulsively stopped from the state of uniform motion is studied. Analytical expressions for velocities of the fluid and dust particles have been obtained. It is found that the dust particles slip on the wall which is brought to rest impulsively instead of sticking to it; on the other hand, they stick to the stationary plate. The slip-velocity of the dust is noticed to be decreasing as the physical time increases and the relaxation time of the dust particles decrease.