Mutual Information-Maximizing Quantized Belief Propagation Decoding of Regular LDPC Codes

In mutual information-maximizing lookup table (MIM-LUT) decoding of low-density parity-check (LDPC) codes, table lookup operations are used to replace arithmetic operations. In practice, large tables need to be decomposed into small tables to save the memory consumption, at the cost of degraded error performance. In this paper, we propose a method, called mutual information-maximizing quantized belief propagation (MIM-QBP) decoding, to remove the lookup tables used for MIM-LUT decoding. Our method leads to a very efficient decoder, namely the MIM-QBP decoder, which can be implemented based only on simple mappings and fixed-point additions. Simulation results show that the MIM-QBP decoder can always considerably outperform the state-of-the-art MIM-LUT decoder, mainly because it can avoid the performance loss due to table decomposition. Furthermore, the MIM-QBP decoder with only 3 bits per message can outperform the floating-point belief propagation (BP) decoder at high signal-to-noise ratio (SNR) regions when testing on high-rate codes with a maximum of 10-30 iterations

Star formation across cosmic time with radio surveys. The promise of the SKA

This lecture briefly reviews the major recent advances in radio astronomy made possible by ultra-deep surveys, reaching microJansky flux density levels. A giant step forward in many fields, including the study of the evolution of the cosmic star formation history is expected with the advent of the Square Kilometer Array (SKA).Comment: 28 pages, 3 figures, to be published in the Proceedings of the 3rd Cosmology School in Cracow, July 201

Trajectory tracking control of pendubot using the Takagi-Sugeno fuzzy sheme

Pendubot is a planar two-link underactuated robotic mechanism and serves as a benchmark example to test developed control algorithms for underactuated mechanical systems. In this thesis we attempt to use the Takagi-Sugeno fuzzy model for the task of the trajectory tracking of the Pendubot. Two proposed control algorithms employ the fuzzy control that is designed by an aggregation of the fuzzy local controllers. For the first control algorithm, the local controller consists of an optimal output feedback plus a term for perturbation rejection, which is design based on the output optimal control and the linear regulatory theory. For the second control algorithm, the local controller is constructed with the state observer. The advantage for such designs is only simple fuzzy controllers are used in the approaches. The proposed two control laws ensure global stability of the closed-loop system and the first one also guarantees the optimal output trajectory trackin

Seismic Fragility Analysis for Structures, Systems, and Components in Nuclear Power Plants

Seismic fragility analysis has been widely used to evaluate seismic capacities of structures, systems, and components (SSCs) in nuclear power plants. In the seismic fragility analysis, a single ground motion parameter (GMP),such as peak ground acceleration (PGA), is chosen to characterize the Review Level Earthquake (RLE) and represent the seismic capacity of an SSC.However, due to the use of a single GMP, problems have been observed in engineering practice. It is well known, from elastic structural dynamic analyses, structural responses under earthquake excitations depend primarily on spectral accelerations at its dominant natural frequencies. Choosing spectral accelerations at structural dominant natural frequencies as vector-valued GMPs (VGMPs) can more accurately characterize the input RLE and more precisely predict structural responses. The purpose of this study is to develop weighting seismic fragility analysis method that overcomes the problems in current seismic fragility analysis method. The proposed method mainly includes that 1. vector-valued probabilistic seismic hazard analysis (VPSHA) is performed to determine the weights of input ground response spectra (GRS); 2. seismic fragility analysis considering VGMPs method is proposed to calculate seismic fragility based on VGMPs; 3. weights of input GRS and seismic fragility are combined to obtain the weighting seismic fragility of an SSC. By using VGMPs, the proposed method resolves the problems in current seismic fragility analysis, thus it can obtain more accurate seismic capacities of safety-related SSCs. In addition, weighting seismic fragility curves and High Confidence and Low Probability of Failure (HCLPF) seismic capacities are represented by a single GMP such as PGA, hence they are readily incorporated into Seismic Probabilistic Risk Analysis and Seismic Margin Assessment (SMA). Based on weighting seismic fragility analysis method, an improved SMA procedure is proposed. The procedure combines the use of weighting and current seismic fragility analysis methods, i.e., 1. weighting seismic fragility analysis is performed to determine HCLPF seismic capacities of “weak link” SSCs, and 2. current seismic fragility analysis is conducted to calculate HCLPF seismic capacities of less important SSCs. This ensures that more accurate plant seismic capacity is obtained, while computational cost is acceptable. The proposed SMA procedure can save redesign cost of “weak link” SSCs. The proposed weighting seismic fragility analysis method is accurate and applicable, providing more accurate seismic capacity estimates of safety-related SSCs, thus saving redesign cost of “weak link” SSCs that do not satisfy seismic margin requirement

Trajectory tracking control of pendubot using the Takagi-Sugeno fuzzy sheme

Pendubot is a planar two-link underactuated robotic mechanism and serves as a benchmark example to test developed control algorithms for underactuated mechanical systems. In this thesis we attempt to use the Takagi-Sugeno fuzzy model for the task of the trajectory tracking of the Pendubot. Two proposed control algorithms employ the fuzzy control that is designed by an aggregation of the fuzzy local controllers. For the first control algorithm, the local controller consists of an optimal output feedback plus a term for perturbation rejection, which is design based on the output optimal control and the linear regulatory theory. For the second control algorithm, the local controller is constructed with the state observer. The advantage for such designs is only simple fuzzy controllers are used in the approaches. The proposed two control laws ensure global stability of the closed-loop system and the first one also guarantees the optimal output trajectory trackin

Automatic measurement of video quality using fuzzy logic

Compression of digital video systems introduces artifacts (i.e., typical types of degradations), such as Blocking, Blurring, and Ringing. In this thesis, a new temporal artifact--'Flashing Blocks' is introduced. This new temporal artifact with other spatial artifacts is integrated into an equation to simulate the goodness of subjective ratings. In the past, linear mapping was used for this mapping. However, in this thesis, a non-linear mapping using Fuzzy Logic is proposed to create the mapping. In this thesis, the performance of these automatic metrics is evaluated by measuring the Mean Square Error between the measures predicted by humans and that predicted automatically. The simulation results indicate that the performance of the automatic metric using Fuzzy Logic is significantly better than those automatic metrics using linear mapping for MPEG-2 test video sequences