Reliability-based Algorithm Research Articles

Time-dependent reliability-based charts to evaluate the structural safety of RC wharf decks exposed to corrosion and freeze-thaw effect

User-friendly time-dependent reliability-based evaluation charts are developed in this research to help practitioners assess the structural safety of existing steel reinforced concrete wharf decks exposed to chloride-induced corrosion and freeze–thaw effect. The research methodology consists of developing a time-dependent reliability-based algorithm using Monte Carlo (MC) simulation, conducting a sensitivity analysis to identify influential parameters that affect the wharf reliability, and calibrating user-friendly evaluation charts. Design examples were provided to demonstrate the use of the evaluation charts for predicting the structural safety of wharves subjected to gravity loads. The margin of error of using the developed charts was found to be less than 2.5% as compared to rigorous time-dependent crude MC simulation.

Self-Adaptive Solution-Space Reduction Algorithm for Multi-Objective Evolutionary Design Optimization of Water Distribution Networks

An effective way to improve the computational efficiency of evolutionary algorithms is to make the solution space of the optimization problem under consideration smaller. A new reliability-based algorithm that does this was developed for water distribution networks. The objectives considered in the formulation of the optimization problem were minimization of the initial construction cost and maximization of the flow entropy as a resilience surrogate. After achieving feasible solutions, the active solution space of the optimization problem was re-set for each pipe in each generation until the end of the optimization. The algorithm re-sets the active solution space by reducing the number of pipe diameter options for each pipe, based on the most likely flow distribution. The main components of the methodology include an optimizer, a hydraulic simulator and an algorithm that calculates the flow entropy for any given network configuration. The methodology developed is generic and self-adaptive, and prior setting of the reduced solution space is not required. A benchmark network in the literature was investigated, and the results showed that the algorithm improved the computational efficiency and quality of the solutions achieved by a considerable margin.

System reliability analysis for anchor-stabilised slopes considering stochastic corrosion of anchors

In this paper, a methodology using Monte Carlo simulation method was developed in conjunction with the modified limiting equilibrium method of slices. Additionally, the time-dependent deterioration of bond capacity of corroding soil anchors was developed in this methodology due to the attack of chlorides. Uncertainties of anchor-related variables and soil parameters were considered using pertinent statistical descriptors. Furthermore, the inherent stochastic nature of the corrosion and degradation process for the anchor/slope system was identified and incorporated in the simulation. A PC-based software, C-UASLOPE, has been coded to allow for handling of complex slope geometry, soil profile and groundwater conditions. An illustrative example was presented to clarify the application of the C-UASLOPE software in modelling the deterioration process to aid in determining the system reliability. The importance of using a system reliability-based algorithm was illustrated by showing that the anchor/slope system may fail unpredictably during design life – even though the initial design results have a high degree of safety – if uncertainties of soil parameters, anchor force and the time-dependent stochastic corrosion process are not accounted for systematically.

A practical algorithm for reliability-based RFID event management considering warehouse operational environment

Radio frequency identification (RFID) technology is considered as a promising identification technology compared to other identification technologies today. However, there are a few factors, which could affect the performance of RFID technology, and cause difficulty in deployment. This paper introduces absurd effects shown by current RFID system with issues in operational environment, and finally presents a reliability-based algorithm to reduce the impact of warehouse operational environment.

Dynamic Check Message Majority-Logic Decoding Algorithm for Non-binary LDPC Codes

Majority-logic algorithms are devised for decoding non-binary LDPC codes in order to reduce computational complexity. However, compared with conventional belief propagation algorithms, majority-logic algorithms suffer from severe bit error performance degradation. This paper presents a low-complexity reliability-based algorithm aiming at improving error correcting ability of majority-logic algorithms. Reliability measures for check nodes are novelly introduced to realize mutual update between variable message and check message, and hence more efficient reliability propagation can be achieved, similar to belief-propagation algorithm. Simulation results on NB-LDPC codes with different characteristics demonstrate that our algorithm can reduce the bit error ratio by more than one order of magnitude and the coding gain enhancement over ISRB-MLGD can reach 0.2-2.0dB, compared with both the ISRB-MLGD and IISRB-MLGD algorithms. Moreover, simulations on typical LDPC codes show that the computational complexity of the proposed algorithm is closely equivalent to ISRB-MLGD algorithm, and is less than 10% of Min-max algorithm. As a result, the proposed algorithm achieves a more efficient trade-off between decoding computational complexity and error performance.