1. Experiments with Replicate Runs at the Cube and Star Points of Inscribed Central Composite Designs

    Julius C. Nwanya1*, Bolarinwa O. Ajala2, Chinyere G. Ihuoma1

    1. Department of Statistics, Imo State University, Owerri.
    2. Department of Mathematical Science, Lagos State University of Science and Technology.

    Abstract: Replication has been a fundamental aspect in any design of experiment. This study looks at the impact replication have on inscribed central composite design (ICCD) when the cube and star points are replicated. The D-, A-,and G-optimality criteria were applied to find the optimal ICCD for experiments when two and three replicate runs are made at the cube and star points of the design at several levels of factor (k = 2 – 7). Results showed that Inscribed central composite design with replicated cube points (ICCD-RF) reduces the A-optimal values of the design in all the factors of considered in the study whereas at lower factors of k (k = 2 and 3), it also reduces the D-optimal values of the design and also increases the G-optimal values for most of the factors considered in the study. Also replication at the star points of Inscribed central composite design (ICCD-RA) increases the A- and D-optimal values of the design in all the factors considered in the study while for G-optimality criterion, replication  at the star points increases the criterion values but not in all the factor levels.

    Keywords: Replication, Inscribe Central Composite Design.

    Pages: 63 – 71 | Full PDF Paper
  2. A New Characterization of Hall Effects on Flow Through Porous Medium in a Rotating Parallel Plate Channel

    Satya Ranjan Pradhani1, Lakshmi Kant Roy2, Umesh Kumar Srivastava3

    1. Research Scholar in Ph.D., University Department of Mathematics, B.R.A. Bihar University, Muzaffarpur – 842001, Bihar, India.
    2. T.P. Varma College, Narkatiyaganj, West Champaran – 845455, B.R.A. Bihar University, Muzaffarpur – 842001, Bihar, India.
    3.R.S.S. College Chochahan, P.O. – Aniruddh Belsar, Dist. – Muzaffarpur – 844111, B.R.A. Bihar University, Muzaffarpur – 842001, Bihar, India.

    Abstract: This paper presents the study of unsteady flow of an incompressible electrically conducting viscous fluid in a rotating porous media, with a variable pressure gradient and in the presence of hall current. Here we consider three different cases, like impulsive change, cosine and sine oscillations of pressure gradient. Here, it is proved in this paper that, the rotational and Lorenz forces are having significant effect on velocity profile in the presence of pressure gradient and hall current.

    Keywords: Unsteady flows, rotating channels, Hall current effects, pressure gradient, impulsive change, Cosine Oscillations and Sine Oscillations..

    Pages: 72 – 84 | Full PDF Paper