Reliability Calculation Method Research Articles

A reliability analysis strategy for main shaft of wind turbine using importance sampling and Kriging model

PurposeWhen dealing with simple functional functions, traditional reliability calculation methods, such as the linear second-order moment and quadratic second ordered moment, Monte Carlo simulation method, are powerful. However, when the functional function of the structure shows strong nonlinearity or even implicit, traditional methods often fail to meet the actual needs of engineering in terms of calculation accuracy or efficiency.Design/methodology/approachTo improve the reliability analysis efficiency and calculation accuracy of complex structures, the reliability analysis methods based on parametric and semi-parametric models are analyzed.FindingsThis paper proposes a reliability method that combines the Kriging model and the importance sampling method to improve the calculation efficiency of traditional reliability analysis methods.Originality/valueThis method uses an active learning function and introduces an importance sampling method to screen sample points and shift the center of gravity, thereby reducing the sample size and the amount of calculation.

A Method for Calculating the Reliability of Welded Metal Bellows for Mechanical Seals

Welded metal bellows are an elastic element widely used in the field of mechanical seals. The main objective of the present study was to investigate the reliability of welded metal bellows in mechanical seals under specified working conditions. To this end, a stress relaxation test bench was built to obtain the residual elastic force data of welded metal bellows under different compression loads in high-temperature environments. Then, the elastic force loss equation of the bellows was fitted. Moreover, a failure judgment form of welded metal bellows in the mechanical seal is proposed. According to the calculation relationship between the seal face pressure and the welded metal bellows’ elastic force, the elasticity force loss range of the bellows was 556–708 N. Finally, according to the elastic force loss equation, elastic force loss was determined. The maintenance time of the welded metal bellows, and the bellow’s failure limit state equation were determined, and the limit state equation was substituted into the center point method. The reliability of the welded metal bellows was 0.9958. The results show that the new failure criterion and the center point reliability calculation method proposed in this paper have certain practical value for the rapid reliability prediction of welded metal bellows.

The Spec-Radiation Method for Layered Fluid Media

The real-time evaluation for non-destructive air-coupled ultrasonic testing of panel materials is a big task for several industries. To make these tests more and more accurate, efficient and reliable calculation methods from ultrasonic holography are essential. In the past, we presented the spec-radiation method as a fast and accurate method for such tasks. The spec-radiation method calculates the sound field utilizing data from a measurement plane at another parallel or tilted plane, especially the sound field at the surface of a panel. This can be used to detect flaws. There is a limitation of the current method: using the data on the panel surface limits the accuracy of the detected flaws. A big step forward could be expected if the sound field in the material were known. As a first step, we developed the spec-radiation method forward to consider multiple material layers. For now, we made the major assumption that all layers have fluid-like properties. Hence, transversal waves were neglected. This extension of the spec-radiation method was validated utilizing an experiment. We present that flaws in the panel material can be detected with higher accuracy at a similar speed compared to our former approach.

Efficient subset simulation for rare-event integrating point-evolution kernel density and adaptive polynomial chaos kriging

Rare-event probability estimation has a wide range of applications, including the design and manufacture of precision equipment, aerospace systems, and critical industrial and civil structures. However, traditional simulation-based reliability calculation methods, such as brute Monte Carlo simulation (MCS) and subset simulation (SS), face challenges in efficiently evaluating small-failure probabilities due to the need for a large number of simulations, especially for non-linear and complex scenarios. Thus, to efficiently assess the probability of rare failure events in structural engineering, this paper develops a novel method for assessing the small-failure probability by integrating the point-evolution kernel density (PKDE), SS, and polynomial chaos kriging (PCK). The proposed PKDE-Adaptive PCK-based SS (PAPS) method aims to reduce the implementation of the original performance function by PCK and enrich the training set using an adaptive strategy. Moreover, the initial cumulative distribution function (CDF) of the performance function estimated by PKDE is modified gradually to facilitate the estimation of small-failure probability. Four numerical examples of small-failure probability estimation involving classical analytical cases, time-variant cases, and non-linear stochastic structures are used to illustrate the accuracy and efficiency of the proposed method. The computational results show that the proposed method can provide accurate computational results with a smaller computational burden than traditional methods (e.g., MCS, SS, LHS-PCK-SS).

A New Stopping Sight Distance Model and Fuzzy Reliability Analysis Comparison

Aiming at the research on the stopping sight distance of the highway, on the basis of calculating the stopping sight distance in the current specification, the actual braking process of the car is divided into three stages: the driver’s reaction stage, the braking force rising stage and the continuous braking stage. The calculation model of the complete braking stage is analyzed by MATLAB, and then the calculation model of the stopping sight distance of the ESC system is proposed. Considering the ambiguity of the operating speed, the fuzzy reliability theory is introduced to establish the function of the fuzzy reliability of the stopping sight distance. Using the Gaussian fuzzy number and the center point method, the reliability index and failure probability of the stopping sight distance are obtained, and the safety of the stopping sight distance is evaluated. According to the "Uniform Standard for Reliability Design of Highway Engineering Structures", the traditional reliability calculation method and the fuzzy reliability calculation method are used to calculate the stopping sight distance value that meets the corresponding reliability index of the highway safety level. The calculated value of the system stopping sight distance model is used as a reference, and the reliability index and failure probability of the two reliability calculation methods are calculated. The calculation results show that: compared with the traditional reliability calculation method, the fuzzy reliability calculation method calculates the stopping sight distance value with higher reliability index, lower failure probability and higher calculation accuracy. Implementing the road design based on the stopping sight distance value calculated by the fuzzy reliability theory can improve the road safety.

The Effect of Soil-Structure Interaction on Vibration Reliability of Transmission Line

Since the main material of the plug-in foundation transmission tower legs is directly connected to the foundation, the traditional reliability calculation method is no longer accurate. For this reason, this paper considers the soil-structure interaction between the foundation soil and the tower legs, replaces the upper limit of the natural circular frequency and frequency ratio of the original iron tower with the corresponding value after considering the SSI (Soil-Structure Interaction), and proposes a SSI-based insertion Analysis method of vibration reliability of type foundation iron tower. First, perform modal analysis to obtain the natural circular frequency of the tower considering SSI; then, according to the external load of the tower under the icing of the wire and the vibration displacement equation of the tower considering SSI, the expression of the comprehensive amplitude amplification factor of the tower is derived, and then the consideration is obtained. The upper limit value of the frequency ratio of SSI and the functional function; finally combined with the normal distribution to solve the problem, the vibration reliability of the plug-in foundation tower considering SSI is obtained. The proposed method has been applied in the analysis of a galloping accident on a line in Guangdong Province. The maximum reliability of the damaged 6-base plug-in foundation tower obtained by this method is 0.9713, which is less than the target reliability of 0.9993.

Monte-Carlo study of pre-neutron emission mass and energy for neutron-induced <sup>232</sup>Th fission

The development of fourth-generation reactors and advanced nuclear energy systems require high-precision, multi-nuclide, and wide-energy-area neutron nuclear data. However, the current nuclear energy-related nuclear fission data in the China Nuclear Data Evaluation Library (CENDL library) are incomplete and cannot meet the current need. It is extremely important to establish the reliable calculation methods and tools for the neutron nuclear data. Based on the Monte-Carlo method, a model for calculating the pre-neutron fission fragment is established in this work. The mass and kinetic energy distribution of <sup>232</sup>Th(n,f) reaction at the medium- and low- incident neutron energy are studied. The calculations of the mass distribution with the different values of incident energy are compared with the experimental results. The maximum deviation of this work from the experimental data is ~1%, which is advantageous compared with the GEF and TALYS code (maximum deviation from the experimental value is ~2%). The calculation of the pre-neutron fission fragment kinetic energy also shows good agreement with experimental result. The results indicate that this model can well describe and predict the characteristics of pre-neutron fission fragment for <sup>232</sup>Th(n,f) reaction at the medium- and low- incident neutron energy. It also provides a new idea for calculating the neutron-induced actinide fission reactions.

Reliability Modeling and Analysis of Multi-Degradation of Momentum Wheel Based on Copula Function

The momentum wheel is a key component of the satellite attitude control system and has a direct impact on the reliability and overall life of the satellite. The momentum wheel has the characteristics of a high reliability, long life, and complex failure mechanics, which leads to expensive maintenance and a low reliability of the test sample. Therefore, it is challenge to implement an accelerated life test. The traditional life data statistical method has great difficulty in solving the reliability analysis of the momentum wheel. A reliability calculation method based on copula function for multi-degradation is proposed. Firstly, the key factors affecting the reliability of the momentum wheel are analyzed, and the lubricant residual quantity and current are selected as the degradation quantity. Secondly, the wiener process is used to model the degradation of a single degradation quantity, and the edge distribution function of the momentum wheel reliability is obtained. Considering that the correlation between multiple degradation quantities has a non-negligible influence on the reliability analysis result, the copula function is introduced to describe the correlation, and the edge distributions are fused to obtain the joint distribution function of the momentum wheel reliability.

Mutual Inductance Calculation of Circular Coils Sandwiched between 3-Layer Magnetic Mediums for Wireless Power Transfer Systems

The mutual inductance between coils directly affects many aspects of performance in wireless power transmission systems. Therefore, a reliable calculation method for the mutual inductance between coils is of great significance to the optimal design of transmission coil structures. In this paper, a mutual inductance calculation for circular coils sandwiched between 3-layer magnetic mediums in a wireless power transmission system is proposed. First, the structure of circular coils sandwiched between 3-layer magnetic mediums is presented, and then a mutual inductance model of the circular coils is established. Accordingly, a corresponding magnetic vector potential analysis method is proposed based on Maxwell equations and the Bessel transform. Finally, the mutual inductance calculation method for circular coils between 3-layer magnetic mediums is obtained. The correctness of the proposed mutual inductance calculation method is verified by comparing the calculated, simulated, and measured mutual inductance data.

Reliability Study of Important Cross-Over Transmission Line System Based on Series System

Transmission lines inevitably cross railroads, highways, and other facilities, and in order to ensure the safety and reliability of the cross-crossing section, the influence of various random factors on important cross-crossing transmission lines needs to be fully considered. In this paper, the transmission line crossing section is treated as a tandem system according to the force transmission route, and the reliability calculation method of the cross-crossing transmission line system based on the tandem system is proposed. The reliability calculation method of each component and the reliability calculation method of the tandem system are given. Finally, an example of the reliability calculation of a 220kV cross-crossing transmission line system is given, and the results show that the cross-crossing section has the highest reliability of tower FSJ404, with a reliability index of 8.61, the second highest reliability of insulators, with a reliability index of 7.22, and the lowest reliability of tower FSJ302, with a reliability index of 4.28. The failure probability of the cross-crossing section is 0.000009245, and the reliability index is 4.28.

Research on reliability evaluation of complex distribution network considering N-1 verification

With the rapid development of power system, the distribution network structure is gradually mature and the connection situation is more complex. The traditional distribution network reliability calculation method can not accurately calculate the reliability index of complex distribution network. Based on the traditional simple power supply reliability evaluation method of radial distribution network, this paper completely considers the influence of circuit breaker, tie switch, branch line, standby transformer and other equipment, and puts forward an improved network equivalence method model. The model first treats the complex distribution system in layers, and then gradually equates it into a simple radial distribution network to calculate the reliability of the system. At the same time, this paper analyzes the distribution network with multi connection structure in a provincial capital city. The results show that this model simplifies the complexity of distribution system reliability calculation, improves the accuracy and speed of reliability calculation, and more truly reflects the reliability of actual distribution system.

Calculating Turns/Amplitude peak ratio of EMG interference pattern by using logistic curve fitting

The aim of the study was to test whether logistic curve fitting (LCF) of Turns = f(Amplitude) plots of single muscle contractions can provide a reliable alternative method for peak-ratio calculation. EMG signals from 74 biceps and 62 triceps contractions were analyzed by applying LCF to Turns = f(Amplitude) plots. Peak-ratio (peak-ratio2) could then be calculated as the point of the fitted line with the highest Turn/Amplitude value. LCF yielded R2 values > 0.95 in the vast majority of contractions studied (68/74 biceps and 53/62 triceps). Peak-ratio2 values had a very strong linear relationship with the corresponding values calculated by the traditional method (peak-ratio1) in both normal and neurogenic conditions. Furthermore, ROC curve analysis showed that peak-ratio1 and peak-ratio2 had similar AUC values. Based on the LCF equation, peak-ratio = T2*(p − 1)/A0*p*(p − 1)1/p. Therefore, peak-ratio is proportional to the maximum number of turns (T2), positively correlated to the rate of turns’ increment at the midpoint of the curve (p) and negatively correlated to the mean amplitude at the midpoint of the curve (A0). A0 is the variable that best discriminates between normal and neurogenic conditions. We provide an alternative method for peak-ratio calculation and show the variables that influence this sensitive marker of neurogenic disease.

A New Safety Assessment Method Based on Belief Rule Base With Attribute Reliability

Safety assessment is one of important aspects in health management. In safety assessment for practical systems, three problems exist: lack of observation information, high system complexity and environment interference. Belief rule base with attribute reliability (BRB-r) is an expert system that provides a useful way for dealing with these three problems. In BRB-r, once the input information is unreliable, the reliability of belief rule is influenced, which further influences the accuracy of its output belief degree. On the other hand, when many system characteristics exist, the belief rule combination will explode in BRB-r, and the BRB-r based safety assessment model becomes too complicated to be applied. Thus, in this paper, to balance the complexity and accuracy of the safety assessment model, a new safety assessment model based on BRB-r with considering belief rule reliability is developed for the first time. In the developed model, a new calculation method of the belief rule reliability is proposed with considering both attribute reliability and global ignorance. Moreover, to reduce the influence of uncertainty of expert knowledge, an optimization model for the developed safety assessment model is constructed. A case study of safety assessment of liquefied natural gas (LNG) storage tank is conducted to illustrate the effectiveness of the new developed model.

The synergic effects of light harvesting and separation of charge carriers, and the optimal band gap of photocatalysts by investigating Bi8V2O17, Bi4V2O11, BiVO4 and Bi4V6O21

The light harvesting and separation of charge carriers are two decisive factors in the photocatalytic process. In order to reveal the synergic effects of light absorption and separation of charge carriers, and put forward the optimal band gaps of specific photocatalytic systems, Bi8V2O17, Bi4V2O11, BiVO4 and Bi4V6O21 series samples with the V/Bi = 0.25, 0.5, 1 and 1.5 were successfully designed and synthesized. UV–Vis diffuse reflectance spectra (DRS) indicated that the visible light harvesting was tremendously enhanced with the increase of V/Bi ratio. Due to the narrow down of band gaps, photoluminescence (PL) illustrated that the separation of electron-hole pairs was gradually restrained. Although Bi8V2O17 showed the best separation of electron-hole pairs, and Bi4V6O21 had the best light harvesting range, but the photocatalytic experiments showed that the optimal sample is Bismuth vanadate (BiVO4). Density functional theory (DFT) calculation has been utilized to explain the above inconsistency, and a promising formula has been put forward to calculate the regularity of light harvesting and separation of electron-hole pairs in the photocatalytic systems. This work constructed the relation between light absorption and separation of electron-hole pairs, and creatively proposed a reliable band gap calculation method to forecast and design of efficient photocatalysts.

Reliability Analysis and Economic Life Calculation for Asset Management Optimization (Case Study in Steam Power Generation Unit at XYZCompany)

In a competitive market driven industry at a power generation business, requires The electricity producers to provide electricity with a low cost of supply. On the other hand, the large number of equipment assets managed by the power plant companies requires an appropriate asset management process, in order to reduce the increased maintenance and investment costs of equipment which which can cause an increase in the cost of supply. XYZ Company as a company that manages assets of more than Rp 174 trillion has challenges in the process of optimizing its company's asset management. The decreasing amount of maintenance and investment budget in the company each year and the equipment conditions that have been operated for more than 20 years, requires an asset management method that can provide a comprehensive understanding of the technical and economic conditions of each equipment, so it can be provide appropriate information to support the decision making process that is expected to reduce cost of supply.In this study, the authors conducted an analysis of asset conditions at XYZ Company by combining the method of reliability analysis and calculation of the economic life of the equipment. Case study was conducted at one of the units at XYZ Company precisely in Steam Turbine Unit 2.0. The purpose of this study is to obtain comprehensive information including the value of reliability and economic life of each equipment in the unit to facilitate management in the decision making process for the selection of maintenance strategies and asset replacement.Reliability analyzes were performed using RBD, RGA, and Weibull software. Reliability calculation will be done by looking at the amount and time between damages. Economic life calculation is done by calculating the annual equivalent cost. The analysis was performed on each equipment in the Steam Turbine Unit 2.0. From this analysis, it’s resulted the procedure for the classification of power plant equipment for the replacement process in accordance with the limits of the parameters of the reliability index and economic lifereliability and economic life conditon. Moreover, It’s resulted the mapping of Steam Turbine critical quipment. This mapping illustrates the amount of equipment that must be replaced immediately, still maintained, and the maintenance strategy needs to be evaluated immediately. This information is used by management in deciding the evaluation of equipment maintenance strategies and replacement strategies to reduce the power plant cost of supply.

Computational Method and Simulation of Reliability for Series, Parallel, and k-Out-of-n Systems with Interval Parameters

For series, parallel, and k-out-of-n voting system reliability calculation methods, the six σ principles have been proposed in this study to derive the interchange relationship between interval parameters and random parameters. The interval reliability index can be expressed in the function of the random reliability index. The interval reliability index can then be transformed into a random reliability index. The computational method of the reliability for series, parallel, and k-out-of-n voting systems with interval parameters is established. Finally, it has been shown that the proposed method is rational, practical, and applicable with two engineering practical simulations.

Structural reliability calculation method based on improved weighted response surface

Structural reliability calculation method based on improved weighted response surface

Optimization of the Water and Fertilizer of Rice in the Cold Field and the Biochar Application Amount Based on RAGA Model

This paper proposes an optimization method based on the RAGA model. Taking rice from a cold area as the research object, this article selects irrigation volume, nitrogen application volume, and biochar application volume as experimental factors, and rice yield, water use efficiency, greenhouse gas emission comprehensive warming potential as influencing indicators. The research design is D311 Field trials by 3 factors of 5 levels of saturation. Hence, we can obtain the data on rice yield, water use efficiency, greenhouse gas emissions and comprehensive warming potential under different levels of water and fertilizer, and biochar application, and regression equations were established respectively. The RAGA model was used to simulate the regression equations. The optimal combination of water and fertilizer, and biochar was obtained as follows: irrigation amount is 7230 m3.hm-2, nitrogen fertilizer application amount is 92.13 kg.hm-2, and biochar application amount is 30 t.hm-2. The optimal rice yield obtained under this combination is 9452.20 kg.hm-2. The water use efficiency is 1.94 kg.m-3, and the comprehensive warming potential of greenhouse gas emissions is 4546.73 kg.hm-2. The combined application of water and fertilizer, and biochar optimized by this model can provide a theoretical basis for achieving high yield, water-saving, and emission reduction of rice in cold areas, and it can also provide a reliable calculation method and idea for solving similar optimization problems in the field of agricultural production.

Analytical model of semi-transparent photovoltaic double-skin façade system (STPV-DSF) for natural and forced ventilation modes

An analytical model has been developed for simulating the semi-transparent photovoltaic double-skin façade (STPV-DSF) system to assess its overall performance. The STPV-DSF integrated building can generate electricity, provide daylight illuminance in its indoor area and lowers the energy demand of a building. During the building design phase, complex simulations are required to estimate the overall performance of the STPV-DSF system. The present study's objective is to provide a reliable and straightforward calculation method for estimating the overall performance of the STPV-DSF system. This paper evaluates the overall performance of STPV-DSF system operating under natural ventilation and forced ventilation for summer and winter seasons of Indian’s composite climate. An experimental investigation has also been carried out on STPV-DSF system to validate the model. A good agreement was observed between measured and calculated temperatures of the STPV-DSF system and solar heat gain to indoor area. For given weather conditions, CO2 emissions and environmental cost (carbon price and emitted carbon quantity) have also been calculated for STPV-DSF systems by solving energy formulations. The results depicted that STPV-DSF system under forced ventilation exhibited 4.08%, 9.86% and 14.05% higher energy performance than natural ventilation in summer and winter with less CO2 emissions.

Study of Pressure Drops and Heat Transfer of Nonequilibrial Two-Phase Flows

Currently, there are no universal methods for calculating the heat transfer and pressure drop for a wide range of two-phase flow parameters in mini-channels due to changes in the void fraction and flow regime. Many experimental studies have been carried out, and narrow-range calculation methods have been developed. With increasing pressure, it becomes possible to expand the range of parameters for applying reliable calculation methods as a result of changes in the flow regime. This paper provides an overview of methods for calculating the pressure drops and heat transfer of two-phase flows in small-diameter channels and presents a comparison of calculation methods. For conditions of high reduced pressures pr = p/pcr ≈ 0.4 ÷ 0.6, the results of own experimental studies of pressure drops and flow boiling heat transfer of freons in the region of low and high mass flow rates (G = 200–2000 kg/m2 s) are presented. A description of the experimental stand is given, and a comparison of own experimental data with those obtained using the most reliable calculated relations is carried out.