The Experts below are selected from a list of 225 Experts worldwide ranked by ideXlab platform

R. N. Singh - One of the best experts on this subject based on the ideXlab platform.

  • Water table fluctuation in response to transient recharge from a rectangular basin
    Water Resources Management, 1994
    Co-Authors: A. Manglik, R. N. Singh
    Abstract:

    A problem of water-table fluctuation in a Finite two-dimensional aquifer system in response to transient recharge from an overlying rectangular area is studied. An analytical solution is obtained by using the method of Finite Fourier Transform to predict the transient position of the water-table. The solution for constant rate of recharge is shown as a special case of the present solution. Effects of variation in the rate of recharge on the growth of two-dimensional groundwater mound is illustrated with the help of a numerical example.

Mazhar Unsal - One of the best experts on this subject based on the ideXlab platform.

  • periodic solution of transient heat flow through multilayer walls and flat roofs by complex Finite Fourier Transform technique
    Building and Environment, 2005
    Co-Authors: Recep Yumrutas, Mazhar Unsal, Mehmet Kanoglu
    Abstract:

    An analytical solution method for the estimation of space heat gain through multilayer walls and flat roofs submitted to periodic boundary conditions is developed. Formulation of the transient heat transfer problem consisting of differential equation and the initial and boundary conditions is converted into dimensionless form and it is solved by the application of complex Finite Fourier Transform (CFFT) technique. This analytical solution is used to determine hourly variation of heat flow into the space through the walls and the temperature at the inner surface of the walls. A computer program is developed based on the analytical model to perform numerical calculations considering six different wall and two different roof constructions, characteristics to the buildings in Turkey. The CFFT technique provides itself as an alternative to other analytical and numerical methods and it appears to be useful in that it allows the calculations to be performed for various multilayer wall and roof constructions and for various climatological locations with varying ambient air temperatures and solar heat inputs.

  • complex Finite Fourier Transform techniques applied to thermal energy storage problems
    1990
    Co-Authors: Mazhar Unsal
    Abstract:

    Fourier series techniques have been applied in the past to many heat conduction problems governed by elliptic and parabolic partial differential equations. Fourier Transform techniques may be used when a problem is not suitable for application of the separation of variables technique. Underground thermal energy storage problems typically lead to problems governed by parabolic type partial differential equations having solutions of periodic behaviour for large values of the time coordinate. Asymptotic solutions of thermal energy storage problems valid for large times can be properly obtained in closed form by application of the complex Finite Fourier Transform technique. Exact periodic solutions for such transient heat conduction problems are reported in this study. Solutions presented can be utilized in seasonal thermal energy storage system simulation studies in cylinderical and spherical coordinates.

A. Manglik - One of the best experts on this subject based on the ideXlab platform.

  • Water table fluctuation in response to transient recharge from a rectangular basin
    Water Resources Management, 1994
    Co-Authors: A. Manglik, R. N. Singh
    Abstract:

    A problem of water-table fluctuation in a Finite two-dimensional aquifer system in response to transient recharge from an overlying rectangular area is studied. An analytical solution is obtained by using the method of Finite Fourier Transform to predict the transient position of the water-table. The solution for constant rate of recharge is shown as a special case of the present solution. Effects of variation in the rate of recharge on the growth of two-dimensional groundwater mound is illustrated with the help of a numerical example.

Mehmet Kanoglu - One of the best experts on this subject based on the ideXlab platform.

  • periodic solution of transient heat flow through multilayer walls and flat roofs by complex Finite Fourier Transform technique
    Building and Environment, 2005
    Co-Authors: Recep Yumrutas, Mazhar Unsal, Mehmet Kanoglu
    Abstract:

    An analytical solution method for the estimation of space heat gain through multilayer walls and flat roofs submitted to periodic boundary conditions is developed. Formulation of the transient heat transfer problem consisting of differential equation and the initial and boundary conditions is converted into dimensionless form and it is solved by the application of complex Finite Fourier Transform (CFFT) technique. This analytical solution is used to determine hourly variation of heat flow into the space through the walls and the temperature at the inner surface of the walls. A computer program is developed based on the analytical model to perform numerical calculations considering six different wall and two different roof constructions, characteristics to the buildings in Turkey. The CFFT technique provides itself as an alternative to other analytical and numerical methods and it appears to be useful in that it allows the calculations to be performed for various multilayer wall and roof constructions and for various climatological locations with varying ambient air temperatures and solar heat inputs.

Ahmed Elhassanein - One of the best experts on this subject based on the ideXlab platform.

  • Spectral Density Estimation of Continuous Time Series
    Applied Mathematics-a Journal of Chinese Universities Series B, 2016
    Co-Authors: Ahmed Elhassanein
    Abstract:

    This paper studies spectral density estimation of a strictly stationary r-vector valued continuous time series including missing observations. The Finite Fourier Transform is constructed in L-joint segments of observations. The modified periodogram is defined and smoothed to estimate the spectral density matrix. We explore the properties of the proposed estimator. Asymptotic distribution is discussed.

  • On the theory of continuous time series
    Indian Journal of Pure and Applied Mathematics, 2014
    Co-Authors: Ahmed Elhassanein
    Abstract:

    This paper considers spectral estimation for a zero-mean strictly stationary r -vector valued continuous time series. The case of interest is when some of observations are missing due to some random failure. Spectral estimation procedures are developed in disjoint segments of observations. Expanded Finite Fourier Transform, modified poriodogram and spectral density statistics are constructed. The theoretical properties of these estimators are developed. Asymptotic distributions are discussed