C. Christopoulos

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This paper presents a transmission-line modeling (TLM) algorithm, which is based upon unstructured tetrahedral meshes. In comparison with the conventional, usually Cartesian, scheme, the use of such meshes provides a significant enhancement in the flexibility and accuracy of the TLM simulations, permitting both smooth boundary approximations and the use of(More)
Time-domain electromagnetic simulations employing unstructured tetrahedral meshes can be sensitive to local mesh characteristics. In particular, the maximum permissible time step for stable operation can be unacceptably small. In this paper, a cell clustering technique is described for the transmission line modeling algorithm that reduces the sensitivity to(More)
A novel node for TLM symmetrical condensed schemes is presented, which unlike existing nodes, contains link lines with the characteristic impedance equal to the intrinsic impedance of modelled medium. Open and short-circuit stubs are loaded into this node in equal proportions, thus ensuring dispersion solutions independent of the wave polarization. Another(More)
This article describes the Durham Family Initiative (DFI), an innovative effort to bring together child welfare and juvenile justice systems to reach DFI's goal of reducing the child abuse rate in Durham, North Carolina, by 50% within the next 10 years. DFI will follow principles of a preventive system of care (PSoC), which focuses on nurturing the healthy(More)
Transmission-line modeling (TLM) is an established numerical simulation method for electromagnetics that has been employed in a wide variety of application areas. To date, TLM has been formulated primarily for structured (usually Cartesian) meshes. This paper presents and illustrates the application of a new TLM algorithm suitable for use with unstructured(More)
Katie D. Rosanbalm, Ph.D., is a research scholar with the Center for Child and Family Policy at Duke University. Dr. Rosanbalm is trained as a child clinical and quantitative psychologist. Her work focuses on child maltreatment prevention and early parenting. Her projects have included the development of a standardized universal risk screening and referral(More)
A technique is described to allow the placement of boundaries at noninteger space step positions within the transmission-line modeling technique without compromising the simulation time step. The development of the 2-D and 3-D modeling procedure is described where the boundary is implemented in the connection process. A previously published technique based(More)
OBJECTIVE As nurse home visiting to prevent child maltreatment grows in popularity with both program administrators and legislators, it is important to understand engagement in such programs in order to improve their community-wide effects. This report examines family demographic and infant health risk factors that predict engagement and follow-through in a(More)
A method for the time-domain simulation of electromagnetic wave propagation in two-level dielectric media is developed. The technique is based on incorporating into transmission-line modelling (TLM) a semi-classical model to simulate the quantum properties of a two-level medium. The approach is accurate and free from numerical instabilities. The approach(More)