Efficient non-uniform orthogonal mesh generation algorithm for cylindrical FDTD applications
The paper presents an efficient non-uniform, orthogonal mesh generation algorithm for the analysis and design of cylindrical microwave devices and integrated circuits using the cylindrical finite-difference time-domain (CFDTD) methods. By using this algorithm, we can easily generate a suitable CFDTD grid which is fitting for the developed CFDTD Maxwell's solver.
Analysis of cylindrical microstrip lines utilizing the finite difference time-domain method
This paper presents full-wave analysis of the cylindrical striplines and the cylindrical microstrip lines utilizing the finite difference time-domain method in a circular-cylindrical coordinate system. Numerical results on the normalized characteristic impedance are in good agreement with the available results. Furthermore, the junctions of the coaxial transmission line and the cylindrical microstrip line are analyzed to show the usefulness of this method. >
Numerical tools applied to power reactor noise analysis
In order to be able to calculate the space- and frequency-dependent neutron noise in real inhomogeneous systems in two-group theory, a code was developed for the calculation of the Green's function (dynamic transfer function) of such systems. This paper reports on the development as well as the test and application of the numerical tools employed. The code that was developed yields the space-dependence of the fluctuations of the neutron flux induced by fluctuating properties of the medium in the two-group diffusion approximation and in a two-dimensional representation of heterogeneous systems, for both critical systems and non-critical systems with an external source. Some applications of these tools to power reactor noise analysis are then described, including the unfolding of the parameters of the noise source from the induced neutron noise, measured at a few discrete locations throughout the core. Other concrete applications concern the study of the space-dependence of the Decay Ratio in Boiling Water Reactors, the noise-based estimation of the Moderator Temperature Coefficient of reactivity in Pressurized Water Reactors, the modeling of the beam- and shell-mode core-barrel vibrations in Pressurized Water Reactors, and the investigation of the validity of the point-kinetic approximation in subcritical systems driven by an external source. In most of these applications, calculations performed using the code are compared with at-power plant measurements. Power reactor noise analysis applications of the above type, i.e. core monitoring without disturbing plant operation, is of particular interest in the framework of the extensive program of power uprates worldwide.