We study the security of communication between a single transmitter and many receivers in the presence of an eavesdropper for several special classes of broadcast channels. As the first model, we consider the degraded multireceiver wiretap channel where the legitimate receivers exhibit a degradedness order while the eavesdropper is more noisy with respect to all legitimate receivers. We establi...

Subchannel codes have been widely used for thermal-hydraulics analyses in nuclear reactors. This paper details the development of a novel subchannel code within Idaho National Laboratory’s (INL) Multi-physics Object Oriented Simulation Environment (MOOSE). MOOSE is parallel computational framework targeted at solution systems coupled, nonlinear partial differential equations, that often arise s...

This paper presents a dynamic discrete bit-loading algorithm for multicarrier pDSL communication links that utilize the indoor power line network. In order to confront the timevarying behavior of power line transmission media, the proposed algorithm provides fast adaptive bit and power loading with reduced complexity using channel state information and a subchannel link-allocation profile. Nume...

Traditional multicarrier techniques perform a frequency-domain decomposition of a channel characterized by frequency-selective distortion in a plurality of subchannels that are affected by frequency flat distortion. The distortion in each independent subchannel can then be easily compensated by simple gain and phase adjustments. Typically, digital Fourier transform schemes make the implementati...

This paper studies multiuser orthogonal frequency division multiplexing (OFDM) system using adaptive subchannel and power allocation with partial channel information. Previous research on multiuser OFDM includes margin adaptive (MA) optimization and rate adaptive (RA) optimization. The capacity gain using adaptive resource allocation over fixed resource allocation such as time division multiple...

A CFD model of VVER-440 fuel assembly heads was developed based on the technical documentation of a full-scale test facility built in the Kurchatov Institute, Moscow. Steady-state and transient calculations were performed to validate the model with a measurement set and investigate the effects of the spatial discretization, choosing of different turbulence models and use of different inlet boun...

In some modern communication systems, as it is the case of WiMAX, it has been decided to implement Demand Assignment Multiple Access (DAMA) solutions. End-users request transmission opportunities before accessing the system, which provides an efficient way to share system resources. In this paper, we briefly review the PHY and MAC layers of an OFDMA-based WiMAX system, and we propose to use a N...