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1. A Simulation and Graph Theoretical Analysis of Certain Properties of Spectral Null Codebooks
2. Error Performance of Concatenated Super-Orthogonal Space-Time-Frequency Trellis Coded MIMO-OFDM System
3. Fault Diagnosis of Generation IV Nuclear HTGR Components using the Enthalpy-Entropy Graph Approach
4. Simulation Study of the Performance of the Viterbi Decoding Algorithm for Certain M-level Line Codes

A Simulation and Graph Theoretical Analysis of Certain Properties of Spectral Null Codebooks by K. Ouahada and H. C. Ferreira
Abstract: The spectral shaping technique and the design of codes providing nulls at rational sub-multiples of the symbol frequency, as the case with spectral null (SN) codes, have enhanced digital signaling over communication channels as digital mass recorders and metallic cables. The study of the special structure of these codes helps in investigating and analyzing certain of their properties which have been proved and emphasized from a mathematical perspective using graph theory. The cardinality of spectral null codebooks reflects the rate of spectral null codes and therefore the amount of transmitted information data. The rate of these codes can also play a role in their error correction capability. The paper presents in different ways the special structure of spectral null codebooks and analyze better their properties. A possible link between these codes and other error correcting codes as the case of Low Density Parity Check (LDPC) is presented and discussed in this paper.
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Error Performance of Concatenated Super-Orthogonal Space-Time-Frequency Trellis Coded MIMO-OFDM System by I. B. Oluwafemi and S. H. Mneney
Abstract: In this paper, we investigate the performance of serially concatenated convolutional code with super-orthogonal space-time trellis code (SOSTTC) in orthogonal frequency division multiplexing (OFDM) over frequency selective fading channels. We consider both recursive systematic convolutional code (RSC) and non-recursive convolutional code (NRC) as the outer code, and 16-state QPSK SOSTTC as the inner code. Employing these, two concatenated schemes consisting of single convolutional outer code and two serially concatenated convolutional outer codes are proposed. We evaluate the performance of the concatenated schemes by means of computer simulations with maximum a posteriori (MAP) algorithm based iterative decoding. Simulation results indicate that the performance of the proposed concatenated schemes improved significantly when compared with schemes without concatenation under the same channel condition.
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Fault Diagnosis of Generation IV Nuclear HTGR Components using the Enthalpy-Entropy Graph Approach by C.P. du Rand and G. van Schoor
Abstract: Fault diagnosis (FD) is an important component in modern nuclear power plant (NPP) supervision to improve safety, reliability, and availability. In this regard, a significant amount of experience has been gained in FD of generation II and III water-cooled nuclear energy systems through active research. However, new energy conversion methodologies as well as advances in reactor and component technology support the study of different FD methods in modern NPPs. This paper presents the application of the enthalpy-entropy (h-s) graph for FD of generation IV nuclear high temperature gas-cooled reactor (HTGR) components. The h-s graph is adapted for fault signature generation by comparing actual operating plant graphs with reference models. Multiple input feature sets (patterns) are generated for the fault classification algorithm based on the error, area, and direction of the fault residuals. The effectiveness of the FD method is demonstrated by classifying 24 non-critical single faults in the main power system of the Pebble Bed Modular Reactor (PBMR) during normal steady state operation as well as load following of the plant. Reference and fault data are calculated for the thermo-hydraulic network by means of a simulation model in Flownex® Nuclear. The results show that the proposed FD method produces different uncorrelated fault signatures for all the examined fault conditions.
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Simulation Study of the Performance of the Viterbi Decoding Algorithm for Certain M-level Line Codes by K. Ouahada
Abstract: In this paper we study the performance of different classes of M-level line codes under the Viterbi decoding algorithm. Some of the presented M-level line codes inherited the state machine structure by using the technique of distance mappings which preserve the properties of binary convolutional codes. Other M-level line codes were enforced to have the state machine structure to make use of the Viterbi decoding algorithm. The technique of spectral shaping was combined with distance mappings to generate spectral null distance mappings (SNDM) M-level line codes. The 2-dB gain between soft and hard decisions decoding for the different classes of M-level line codes is investigated. The standard technique for assessing the stability and the accuracy of any decoding algorithm, which is the error propagation is used to analyze the stability and the accuracy of the Viterbi decoding algorithm of the M-level line codes. The obtained results have shown advantages and outperformance of SNDM codes compared to the rest of line codes presented in this paper.
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