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Uncertainty Quantification Code Written in MATLAB
(2024-01-01)
Suratemeekul, Napat
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Kumkam, Noppawit
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Sleesongsom, Suwin
This research presents examples of MATLAB code for a classroom of uncertainty quantification. The codes are developed for educational purposes and newcomers or researchers. Demonstration codes are presented in form of a general design conditions. Examples are chosen from mechanical components, which are simply understood. The mechanical components are shafts, connecting rod, rear shaft housing, and bolt etc. The quantification techniques are in the group of probabilistic such as Monte Carlo Simulation (MCS) and Latin Hypercube Sampling (LHS). These examples can help the newcomers to understand the difficulty in uncertainty quantify and extend to calculate reliability value and probability of failure. Example computer codes are included in all parts.
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Reliability enhancement of LNG fuel gas supply system in combined-cycle power plant
(2020-12-01)
Thepmanee, Teerawat
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Nachasingha, Chakri
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Kummool, Sart
This article aims to present a technique to enhance reliability of liquefied natural gas (LNG) fuel gas supply system (FGSS) of gas turbine unit in a combined-cycle power plant. In order to prevent unplanned plant shutdowns, the proposed technique is based on the use of failure modes, effects, and diagnostic analysis (FMEDA) to identify and evaluate the effects of possible failure modes, to determine what could minimize the chance of failures, and to design a new safety interlock. The studied FGSS consists of gas analytical system (GAS) in 2-out-of-2 voting scheme, shutdown valve system (SDV) in 1-out-of-2 voting scheme, fuel gas controller (FGC), and engineering/operator workstations. Two automatic GAS subsystems with different measurement methods are installed in the GAS. One of two GAS subsystems uses three gas chromatography analyzers in 2-out-of-3 voting scheme. The gas chromatography results and diagnostic alarm historian are utilized to consider the failure behavior. The reliability models for the GAS subsystem using gas chromatography and the overall FGSS are also included to confirm the effectiveness of utilizing diagnostic information from the gas analyzers. Based on the FMEDA results, the new safety interlock with no additional software and hardware costs can be achieved. The workability of the proposed safety interlock is demonstrated by test results.
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Multi-objective reliability-based topology optimization of structures using a fuzzy set model
(2020-10-01)
Sleesongsom, Suwin
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Bureerat, Sujin
This research proposes a multi-objective reliability-based topology optimization (MORBTO) for structural design, which considers uncertain structural parameters based on a fuzzy set model. The new technique is established in the form of multi-objective optimization where the equivalent possibilistic safety index (EPSI) is included as one of the objective functions along with mass, and compliance. This technique can reduce complexity due to a double-loop nest problem used previously due to performing single objective optimization. The present technique can accomplish within one optimization run using a multi-objective approach. Two design examples are used to demonstrate the present technique, which have the objectives as structural mass and compliance with the constraint of structural strength. The results show the proposed technique is effective and simple compared to previous techniques.
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Design and Implementation of Functional Safety for Repairable Systems
(2018-10-15)
Julserccwong, Amphawan
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Thepmanee, Teerawat
This paper focuses on a practical technique based on IEC 61508 and IEC 61511 standards to design and implement the functional safety for repairable systems. A pilot plant for pressure control under real-world operating conditions is employed as a case study to demonstrate the effectiveness of the proposed design and implementation. The fault trees are utilized to model and analyze the reliability of two sensing elements, two logic solvers, and two final elements used in the designed safety instrumented function (SIF) in terms of probability of failure on demand (PFD). The values of mean time to restore (MTTR) as well as the impacts of proof test effectiveness are considered in reliability modeling of the designed SIF for the case study. Plotting the created PFD equations in MATLAB shows the impacts of perfect and imperfect proof tests during the mission time of the designed SIF. The safety integrity level (SIL) verification shows that the designed SIF can meet the target SIL. The hardware installation for implementing the designed SIF is also described.
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Evaluation of generation system reliability using adaptive neuro-fuzzy inference system (ANFIS) and artificial neural networks (ANNS)
(2018-01-01)
Wannakam, Khanittha
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Jiriwibhakorn, Somchat
This paper presents an evaluation of the reliability index of power generation systems using the Adaptive Neuro-Fuzzy Inference System (ANFIS) and Artificial Neural Networks (ANNs) to compare the results obtained from the basic method of probability. The reliability index used in this study is the Expected Energy Not Supplied (EENS) index, which is used in planning to increase the installed capacity for the adequate demand for electricity. The ANFIS and ANNs techniques will learn the relationship between the priority level, the installed capacity and the force outage rate (FOR) of the generator, which significantly affect the EENS index. The results indicated that the ANNs techniques have the best predictive performance. The best accuracy of the training data was 1.2488% and the testing data was 2.3963%, calculated using a Mean Absolute Percentage Error (MAPE). Furthermore, the ANNs took more time to learn faster than the ANFIS.
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Thailand’s automotive service quality customer satisfaction: A servqual model cfa of suzuki mo
(2018-01-01)
Chaichinarat, Pichaipat
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Ratanaolarn, Thanin
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Kiddee, Krissana
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Pimdee, Paitoon
Thailand’s automotive industry is the 12th largest in the world and plays an important role in Thailand’s economy. Under the government mandated Thailand 4.0 vision, the automotive sector has been identified as one of the 10 crucial sectors for future economic growth. Within this sector, service quality has repeatedly been identified as one of the most competitive factors amongst the major dealers. Service quality is a fundamental aspect of service provisioning, which demonstrates excellence and long-term success. The purpose of this paper is, therefore, to investigate service quality within Thailand’s Suzuki Motor Company by adopting the five dimensions of the SERVQUAL model (tangibles, reliability, responsiveness, assurance, empathy) for analysis. Additionally, the study also examined the validity of the service quality model and compared service quality satisfaction amongst Thailand’s Suzuki Motor Company service staff. By using multi-stage random sampling, 537 customers responded. Using both quantitative and qualitative research methods, the main research instrument was a questionnaire which used a 5-point Likert type agreement scale. An analysis was undertaken in which the mean ( standard deviation (S.D.), correlation analysis, and percentage were evaluated. Furthermore, a second-order confirmatory factor analysis was performed using Mplus Version 8 software. The statistical values were Chi-square = 2572.016, df = 979, RMSEA =.07, SRMR =.051, TLI =.901, CFI =.912. Results from the five identified dimensions were in line with the hypothesized model, with the weight of all the variables being positive. These included responsiveness, empathy, reliability, tangibility, and assurance.
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Reliability modeling of emergency shutdown function for heat recovery steam generator control
(2016-10-01)
Chairuan, Chaichan
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Julsereewong, Amphawan
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Thepmanee, Teerawat
This paper presents a method for evaluating reliability and unreliability of emergency shutdown function for a control system of heat recovery steam generator (HRSG), which is operated with active redundant for providing safety and protection. The studied triple-pressure HRSG for driving the steam turbine in a power plant consists of three sections: high pressure section, intermediate pressure section, and low pressure section. A safety shutdown is based on level and pressure sensing system with three pressure transmitters and three level transmitters in each section for implementing a voting algorithm in order to tolerate the failure ofone sensor. Fault tree analysis (FTA) is employed as a tool for analyzing probability functions ofsuccess and failure for three possible voting algorithm configurations. Based on the obtained modeling, complex data of the studied system are transformed to accurate prediction of its reliability and unreliability.
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Improvement of pavement design and management for more frequent flooding caused by climate change
(2015-04-01)
Wang, Yuhong
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Huang, Yu
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Rattanachot, Wit
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Lau, K. K.
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Suwansawas, Suchatvee
Climatological records show a trend of the increasing occurrence of extreme weathers caused by global climate change. One form of extreme weathers is heavy rainfall which, combined with rising sea levels, made highways in some subtropical regions susceptible to flooding. Flooding in these regions causes noticeable damages to flexible highway pavements. However, little research has been conducted to quantify such damages and develop possible mitigation measures. This study developed a method to incorporate flood risk into the structural analysis of flexible pavements, examined the effects of flooding on pavement materials and structures through laboratory tests and design simulations, and recommended better pavement design and management strategies. Flexible pavement is found to be significantly affected by flooding. Future climate change and the resultant increase of flooding frequency pose a serious challenge to the reliability of flexible highway pavements. To mitigate the detrimental effects of flooding, pavement thickness and drainage system need to be adequately designed and post-flood traffic control may need to be imposed.
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The effects of distributed generator on distribution system reliability
(2015-01-01)
Khuanpaed, S.
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Ngaopitakkul, A.
The purpose of this paper is to study the effect of distributed generator (DG), which is solar photovoltaics (PV) integrated into the distribution system of Provincial Electricity Authority (PEA) in terms of cost, Feed-in Tariff (FiT) and reliability. The distributed generator (DG) under this study is connected to a 22 kV distribution system of Thanyaburi substation on the PEA, which is a part of Thailand's distribution system. In addition, when the installed DG is increased, cost, Feed-in Tariff (FiT) and reliability are considered. The System Average Interruption Frequency Index (SAIFI), The System Average Interruption Duration Index (SAIDI) and Outage Cost are assessed as reliability indices. The reliability indices will be calculated using data obtained from simulation and analysis of power distribution system models created in DIgSILENT. The overall results can be summarized by focusing on the capacity of DG and the location of DG, which are important factors capable of affecting the reliability indices.
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Topological communication network design using ant colony optimization
(2005-01-01)
Premprayoon, Patomporn
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Wardkein, Paramote
In this paper, Ant Colony Optimization (ACO) is proposed to solve the optimal telecommunication networks design considering both economics and reliability. ACQ is a new cooperative agent approach, which is inspired by the observation or the behaviors of real ant colonies on the topic of ant trial formation and foraging methods. In the ACO, a set of cooperating agents called "ants" cooperates to find good solution. The advantages of ACO are parallel search and optimization capabilities. This approach is interested on the model of the reality telecommunication network. Simulation results on multiple test problems with various degrees of constraint show that this approach has high efficiency and is superior to the conventional Tabu Search algorithm (TSA).

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