Reliability Analysis Procedure Research Articles

Resiliency Scales – tool adaptation and a preliminary analysis of psychometric properties

The presented study aimed to adapt the Resiliency Scales – A Profile of Personal Strengths in a group of 357 students (178 adolescents with mild intellectual disability and 179 students within intellectual norm) and to conduct a preliminary analysis of its psychometric properties. In accordance with the theoretical background of the completed analyses – resilience theory – the respondents taking part in the study have experienced various challenges during their life. The Resiliency Scales – A Profile of Personal Strengths intends to measure such personality traits of an individual that enable them to better overcome difficulties and adversity (Prince-Embury, 2006). The first stage of the psychometric verification was to study descriptive statistics and distribution. The next stage was reliability analysis and confirmation procedure for factor analysis. The last phase of the adaptation was to standardize the results and prepare norms. As a result of the performed analyses, it can be concluded that Resiliency Scales – A Profile of Personal Strengths is characterized by satisfactory psychometric properties.

Subset simulation based simplified approach for pipeline with multiple irregular corrosion defects in time-dependent reliability analysis

Pipeline system plays an important role in the natural gas and petroleum transportation, and it is widely employed in the engineering application. However, the pipeline system is subjected to corrosion given the industry environment condition, or soil condition when it is buried. In this case, it is important to assess the remaining life of corroded pipeline. Consequently, it is important to predict the failure probability considering the corrosion growth over time and operating pressure. Nevertheless, the prediction of failure probability in corroded pipeline in not an easy task, due to the fact that a realistic corrosion usually has an irregular geometry, especially, when multiple irregular corrosion is involved in the analysis. To simplify the problem, this work presents a simplified procedure for time-dependent reliability analysis to predict the failure probability in pipeline with multiple irregular corrosion defects, considering two failure modes, the burst and leak mode. The approach is based on Subset Simulation and Weighted Depth Difference method, where the multiple irregular corrosion is treated by a discretization procedure and a weighting coefficient is evaluated in every discretization points. Then, this weighting coefficient is introduced into burst pressure assessment, which is employed by burst failure mode limit state function. In this work, the corrosion growth is modelled by power function corrosion model, and initial corrosion depth is generated randomly. The Subset Simulation is employed to evaluate the failure probability, where the Markov Chain Monte Carlo is adopted to evaluate the conditional probability and Metropolis-Hasting algorithm is employed to solve the problem. Finally, several scenarios with single and multiple irregular corrosion defects are analyzed to demonstrate the effectiveness of presented procedure.

Fan-out panel-level package warpage and reliability analyses considering the fabrication process

With the continuous advancement of IC packaging technology, 3D and 2.5D packaging systems have emerged as the prevailing trends. The advantages of large area and high I/O density have made fan-out panel-level packaging (FOPLP) been considered as one of the best package types for 3D and 2.5D packaging applications. The discussions about FOPLP have been popular recently. Warpage and reliability of FOPLP are the main concerns of packaging engineers. However, it was found that warpage and reliability of FOPLP are strongly related to the fabrication process but not many research works have been published. Thus, reliability analysis procedure considering the residual stress of fabrication process was proposed in this paper to observe warpage and stress distribution during fabrication process. Then, this research procedure facilitates subsequent fatigue life calculations and predicts reliability of the package.First, the thermal stresses and warpage of the redistribution layer-first (RDL-first) process were conducted for an entire panel. Next, warpage and thermal stress analyses were conducted for a strip encapsulated with an epoxy molding compound (EMC) during compression molding. Then, a reliability analysis was conducted with an IC unit and incorporated the consideration of the residual stress induced during the fabrication processes.The compression molding analysis utilized the pressure–volume–temperature–cure (P–V–T–C) model to account for both the volume shrinkage caused by a thermal mismatch and the chemical shrinkage. Furthermore, dual shift factor model was used to model the viscoelastic behavior of EMC in this study during PMC analysis effectively.An observation of the stress distribution for an IC unit revealed that the maximum stress position was at the solder ball near the periphery, with a stress value of 147.309 MPa. The fatigue life calculated using the modified Coffin–Manson fatigue model was 417 cycles.

A sequential sampling-based Bayesian numerical method for reliability-based design optimization

For efficiently solving the Reliability-Based Design Optimization (RBDO) problem with multi-modal, highly nonlinear and expensive-to-evaluate limit state functions (LSFs), a sequential sampling-based Bayesian active learning method is developed in this work. The penalty function method is embedded to transform the constrained optimization problem into a non-constrained one to reduce the model complexity. The proposed method for solving RBDO problems starts by training a Gaussian process (GP) model, in the augmented space of random and design variables. It is then based on an efficient sampling scheme for simulating the GP model, the adaptive Bayesian optimization (BO) and Bayesian reliability analysis (BRA) procedures are combined in a collaborative way for sequentially producing the joint training points. BO driven by expected improvement (EI) function is used for inferring the global optimum in the design space with global convergence, and the BRA equipped with U function is implemented for inferring the failure probabilities at the identified design points with the desired accuracy. The superiority of the proposed method is demonstrated with two numerical and two real-world engineering examples.

Integrated reliability analysis procedure for spatially variable soil slopes using recursive FORM algorithm enhanced by importance sampling: Abaqus via Python implementations

ABSTRACT This paper proposes an efficient geotechnical reliability analysis framework that integrates the advantages of the first-order reliability method (FORM) and the Karhunen-Loève expansion (KL) to evaluate the reliability of spatially variable soil slopes. The improved Hasofer-Lind-Rackwitz-Fiessler (iHLRF) recursive algorithm is adopted to implement the FORM procedure when coupled with finite element codes for slope stability analysis, and the KL is used to reduce the dimension of random variables representing the soil random fields. To enhance the accuracy of the failure probability estimated by KL-iHLRF, the importance sampling (IS) is also conducted in this study, resulting in an innovative slope reliability analysis framework, KL-iHLRF-IS. It is found that although the FORM analysis by itself may not be able to confidently estimate the failure probability of spatially variable soil slopes because of the very high dimension of random variables and the strong nonlinearity of the limit state function, it provides useful information on the design point values for KL-iHLRF-IS to rapidly compute the failure probability. The efficiency of KL-iHLRF-IS for slope reliability analysis is illustrated by three example slope case studies. The proposed framework is particularly useful when fast yet accurate slope reliability analysis using the finite element method is needed.

L-Moments-Based FORM Method for Structural Reliability Analysis Considering Correlated Input Random Variables

Leveraging the properties of the first three linear moments (L-moments), this study proposes an effective normal transformation for structural reliability analysis considering correlated input random variables, in which the admissible range of the initial correlation matrix when employing this transformation is also presented. Subsequently, a practical procedure for structural reliability analysis, grounded in the proposed transformation and first-order reliability method (FROM), is proposed, accommodating instances wherein the joint probability density functions (PDFs) or marginal PDFs of the relevant random variables remain unknown. In comparison to the technique premised on the first three central moments (C-moments), the proposed method, based on the first three L-moments, exhibits a more extensive applicability. Various practical scenarios showcase the method’s effectiveness and precision in calculating the structural reliability index, considering diverse distributions, numerous variables, and complex structures.

The Chinese version of the skin tear knowledge assessment instrument (OASES): Cultural adaptation and validation

BackgroundSkin tear knowledge is an important predictor of the decreased incidence and management of skin tears, and the knowledge level among Chinese nurses is unknown so far. A validated instrument for measuring skin tear knowledge is urgent. ObjectiveTo culturally adapt the skin tear knowledge assessment instrument (OASES) into Chinese and verify its validity and reliability in the Chinese context. MethodsThe cultural adaptation process for OASES into Chinese was established on Beaton's translation model. Content validity was determined by the 8-expert group in wound care. A nationwide psychometric validation study was performed on a convenience sample of 3333 nurses from 113 tertiary hospitals, of whom 98 nurses finished the test-retest procedure for reliability analysis. Item validity (item difficulty and discriminating index) and construct validity (known-groups technique) were tested. ResultsThe content validity index was 0.88–1.00. The item validity was as follows: Item difficulty ranged from 0.16 to 0.86, with an average value of 0.52; the discriminating index varied between 0.05 and 0.61. The known-group technique demonstrated excellent construct validity with a significant difference between predefined groups with theoretically expected higher knowledge scores and theoretically expected lower knowledge scores (P < 0.001). For the test-retest reliability, the Intraclass correction coefficient (ICC) during a 14-day interval for the overall tool was 0.79 (95% CI = 0.71–0.86), and Cohen's kappa value for each item varied from 0.17 to 0.62. ConclusionsThe Chinese version of OASES was validated to be suitable for skin tear knowledge assessment with acceptable psychometric properties, through which the knowledge and training priorities of skin tear among Chinese nurses can be quantified.

Time-variant reliability analysis of underground structures against delayed failure based on the probability density evolution method

The unpredictable delayed failure of underground tunnels may occur after excavation due to the time-dependent behavior of surrounding rock mass, which brings a new consideration to the reliability evaluation of underground structures. In this study, a time-variant reliability analysis procedure via the probability density evolution method (PDEM) is proposed for underground tunnels against delayed failure. The creep-damage theory is introduced to model the time-dependent behavior of rock materials. A new energy-based stability criterion is developed to identify the structural delayed failure. By applying the PDEM with the absorbing boundary condition, the time-varying reliability of underground structures can be obtained. The proposed procedure is applied to a case study involving the deep tunnel with uncertain material parameters. Numerical results demonstrate that the inherent variability of rock properties could result in the large fluctuation of structural delayed responses, which has a significant influence on the time-varying reliability of the tunnels.

The New Method of Searching Cut-Sets in the System Reliability Analysis of Plane Steel Trusses

This paper focuses on the new method of searching cut-sets, which enables us to conduct the system reliability analysis for plane trusses. As the result of such, the analysis of the reliability index for the whole structure is obtained, not only for the single elements. In the case of truss structures, the huge number of cut-sets could be generated if only the geometry of the structure is taken into account. Considering also the effects of actions and the load capacity, it is possible to reduce the number of cut-sets: what makes the whole analysis faster and more effective. The structures were considered not only in persistent design situations, but also in accidental-under-fire influence. The effect of action in individual elements was computed using the Robot Structural Analysis program. The temperature of the elements under fire load and the load-bearing capacity of the elements were calculated according to the Eurocode procedure in the Mathematica script. The proposed method allows to reduce the number of cut-sets, what makes the whole procedure of system reliability analysis much more efficient. All cut-sets were found by using a C++ console application prepared by author.

Multiscale reliability analysis of composite structures based on computer vision

The geometric uncertainties of composite structures are considered in the multiscale reliability problem. A convolutional neural network (CNN) is developed and trained using deep learning to link geometric uncertainties and the randomness of structural responses or performances. The CNN training set includes graphical samples and corresponding stress components and strength characteristics of the lamina. A method for generating a graphical sample is developed, which integrates the stochasticity of the fibre shape, misalignment, arrangement, volume fraction, matrix voids, and stacking sequences of the laminates. The corresponding stress components are simulated using the Kernal–Hashin model and laminate plate theory. A reliability analysis procedure is developed using a Monte Carlo simulation. Numerical cases are presented to demonstrate the validity of the proposed method.

System reliability-based design of steel-concrete composite frames with CFST columns and composite beams

This paper presents an effective reliability analysis procedure and proposes the system resistance factors for the system design of steel-concrete composite frames that comprise of concrete-filled steel tubular (CFST) columns and composite beams. Advanced analysis is employed to predict the ultimate resistance of frames using fibre beam-column elements in OpenSees. The obtained predictions of the load-carrying capacity of frames compare well with experimental results with the mean value of the test-to-prediction ratio around 1.027 and the coefficient of variation (CoV) of 8.4%. Both Monte Carlo (MC) and subset simulations are used in the reliability analysis. The uncertainties of model error, geometric and material properties, and external loads are included to predict the system reliability index. Five different frame configurations are considered. The results of the reliability analysis show that the system resistance factors for both US and AS codes are quite similar. In the case of gravity load, the system resistance factor is from 0.78 to 0.90, whilst this value for the case of combined wind and gravity load is from 0.8 to 0.95. The resistance factors suggested herein become valuable reference information for the system design of composite frames.

Berthing time in the port of Tanjung Priok, Jakarta, Indonesia

This paper examines the health operations flexibility dimensions in the United Arab Emirate in the healthcare sector by employing Structural Equation Modeling (SEM) approaches. The study also attempts to determine the numbers for the operational flexibility dimensions which will help the researchers in future find healthcare operational flexibility dimensions valid and reliable. A model consisting of two constructs of operations flexibility structures: external flexibility and internal robustness is examined to measure health operations flexibility elements in service sectors. Respondents are the health leaders (managers, middle manager, top manager and others) who were working in health service sectors in the United Arab Emirate. The underlying constructs of operations flexibility are empirically verified and validated through Reliability Analysis Procedure, Exploratory Factor Analysis (EFA), First and Second Confirmatory Factor Analysis, and Construct Validity Procedures, Structural Equation Modeling (SEM) was employed to test the model, drawing on a sample of 250. The findings revealed that the model of the UAE health service sector consists of two latent's operations flexibility dimensions namely external flexibility and internal robustness, each dimension consisting of four items. Further research should be considered to validate these findings in the other firms. The two dimensions of health operations flexibility represent a valid instrument to measure the operations flexibility in the services sector in the United Arab Emirate. This research is important for one to understand the main topics of health operations flexibility in the health services sector.

Validating the operational flexibility dimensions in the medical service sectors

This paper examines the health operations flexibility dimensions in the United Arab Emirate in the healthcare sector by employing Structural Equation Modeling (SEM) approaches. The study also attempts to determine the numbers for the operational flexibility dimensions which will help the researchers in future find healthcare operational flexibility dimensions valid and reliable. A model consisting of two constructs of operations flexibility structures: external flexibility and internal robustness is examined to measure health operations flexibility elements in service sectors. Respondents are the health leaders (managers, middle manager, top manager and others) who were working in health service sectors in the United Arab Emirate. The underlying constructs of operations flexibility are empirically verified and validated through Reliability Analysis Procedure, Exploratory Factor Analysis (EFA), First and Second Confirmatory Factor Analysis, and Construct Validity Procedures, Structural Equation Modeling (SEM) was employed to test the model, drawing on a sample of 250. The findings revealed that the model of the UAE health service sector consists of two latent's operations flexibility dimensions namely external flexibility and internal robustness, each dimension consisting of four items. Further research should be considered to validate these findings in the other firms. The two dimensions of health operations flexibility represent a valid instrument to measure the operations flexibility in the services sector in the United Arab Emirate. This research is important for one to understand the main topics of health operations flexibility in the health services sector.

Comprehensive system limit state function model and its application for CRTS II track slab

ABSTRACT Considering safety and serviceability simultaneously, a comprehensive system limit state function (LSF) model and its application for CRTS II track slab is analyzed. First, a comprehensive system LSF model is proposed, and the procedure of comprehensive system reliability analysis is developed from integrating the method of moments with finite element (FE) code. Second, based on the proposed model, comprehensive system LSF of CRTS II track slab is constructed, considering five important safety failure modes and three important serviceability failure modes. Then, comprehensive system reliability of a CRTS II track slab on simply supported viaduct is analyzed using the proposed method, and the result is compared with general system reliabilities considering safety and serviceability separately. It is found that the proposed comprehensive system LSF model has a flexible form and the proposed methodology can be efficiently applied for comprehensive system reliability assessment. It is also found that comprehensive system reliability analysis is more appropriate compared with general system reliability analysis, and thus, comprehensive system reliability results can help to determine an appropriate maintenance strategy and ensure the safety operation for high-speed trains.

Response and reliability analysis of random time-delay controlled systems undergo wide-band random excitations

This paper proposed a new procedure for response and reliability analysis of a multi-degree-of-freedom (MDOF) random time-delay controlled nonlinear system subjected to wide-band random excitations. A two-steps method is presented to deal with random time delay: Firstly, by modeling the random jump time-delay as a Markov jump process, the random delayed control is formulated as the one with discrete Markov jump varying delay; secondly, based on the randomly periodic property of the system, the Markov jump delay is taken out of the control as a parameter. A new scheme based on limit averaging and stochastic averaging principle is developed, which suppresses the rapidly varying processes to generate a less-dimensional probability-weighted system. The Fokker–Planck–Kolmogorov (FPK) equation and the backward Kolmogorov (BK) equation are then deduced and solved, from which the quantitative characteristics of the response and reliability of the system are obtained. Finally, an example is worked out in detail, from which the application and effectiveness of the proposed method are demonstrated.

Modelling and comparison of different types of random fields: case of a real earth dam

The random field (RF) theory is widely used for describing the soil spatial variability in geotechnical engineering. This article presents soil variability modellings by using different types of RF-based on the available measurements of an earth dam. The effects of these RFs on dam reliability are investigated as well. The studied dam is well-documented, and there are many geo-localized measurements for the dry density. These measurements are firstly used to estimate the basic parameters of unconditional-stationary RFs and are then explored to define two more complex RFs (one is conditional RF and the other considers the mean variation with depth). The three mentioned types of RFs are all implemented in the same reliability analysis procedure for comparison. The results demonstrate that using different RFs for soil spatial modelling would induce insignificant differences in terms of reliability results if the dam construction was well controlled (careful selection for the construction material and controlled compaction). Therefore, a simple RF (unconditional-stationary) is enough to obtain satisfactory results in the case of carefully controlled dams during their construction. Otherwise, conditional RFs are recommended if more accurate results are needed, given that this type of RF is conditioned on the available data and can consider the non-stationarity of a soil property.

PV Inverter Reliability-Constrained Volt/Var Control of Distribution Networks

The increasing penetration of photovoltaic (PV) systems promotes utilization of PV inverters for volt/var control (VVC) in distribution networks. However, PV inverters are vulnerable and their reliability is one of the most critical concerns for sustainable PV energy utilization. To enhance PV inverter reliability, this paper proposes a PV inverter reliability-constrained VVC method of distribution networks under uncertainties. Firstly, a full reliability analysis procedure for PV inverters is developed to estimate the lifetimes of core devices inside inverters. Secondly, considering the impacts of VVC on PV inverter reliability, reliability constraints are proposed based on regulation of inverter apparent power and application of a PV curtailment scheme. Thirdly, a multi-objective PV inverter reliability-constrained VVC optimization model is proposed, which aims to minimize network power loss and PV curtailed power, simultaneously. Accordingly, the nonconvex model is relaxed by a second-order cone programming method, and the uncertainties such as PV power generation and loads are addressed by a scenario-based stochastic optimization method. The proposed VVC method is tested on the 33-bus and 69-bus distribution networks, and the simulation results verify high efficiency of the proposed method in energy loss reduction and inverter reliability enhancement.

Reliability and reliability-based sensitivity analysis of self-centering buckling restrained braces using meta-models

This paper aims to carry out sensitivity analyses to study how the effect of each design variable on the performance of self-centering buckling restrained brace (SC-BRB) and the corresponding buckling restrained brace (BRB) without shape memory alloy (SMA) rods. Furthermore, the reliability analyses of BRB and SC-BRB are performed in this study. Considering the high computational cost of the simulation methods, three Meta-models including the Kriging, radial basis function (RBF), and polynomial response surface (PRSM) are utilized to construct the surrogate models. For this aim, the nonlinear dynamic analyses are conducted on both BRB and SC-BRB by using OpenSees software. The results showed that the SMA area, SMA length ratio, and BRB core area have the most effect on the failure probability of SC-BRB. It is concluded that Kriging-based Monte Carlo Simulation (MCS) gives the best performance to estimate the limit state function (LSF) of BRB and SC-BRB in the reliability analysis procedures. Considering the effects of changing the maximum cyclic loading on the failure probability computation and comparison of the failure probability for different LSFs, it is also found that the reliability indices of SC-BRB were always higher than the corresponding reliability indices determined for BRB which confirms the performance superiority of SC-BRB than BRB.

From Digital Divide to Information Availability: A Wi‐Fi‐Based Novel Solution for Information Dissemination

Digital divide means unequal access to the people for information and communication technology (ICT) facilities. The developed countries are comparatively less digitally divided as compared to developing countries. This study focuses on District Chitral considering its geographical conditions and high mountainous topography which plays a significant role in its isolation. Aside from the digital divide, the situation in Chitral is even more severe in terms of the absence of basic ICT infrastructure and electricity in the schools. To address this issue, especially in female secondary and higher secondary schools, we designed a project to bridge the digital divide via Wireless Local Area Network on Raspberry Pi3 for balancing the ICT facilities in the targeted area. The Wi‐Fi‐Based Content Distributors (Wi‐Fi‐BCDs) were provided to bridge the digital divide in rural area schools of Chitral. The Wi‐Fi‐BCD is a solar‐based system that is used to deliver quality educational contents directly to classroom, library, or other learning environments without electricity connection and Internet wire as these facilities are available by default in it. The close‐ended questionnaire was adopted to collect data from the students, teachers, and headmistresses of girl secondary and higher secondary schools in Chitral. The procedure of validity, reliability, regression, correlation, and exploratory factor analysis was used to analyze the obtained data. The technology acceptance model (TAM) was modified and adopted to examine the effects of Wi‐Fi‐BCD for bridging the digital divide. The relationship of the modified TAM model was examined through regression and correlation to verify the model fitness according to the data obtained. The result analysis of this study shows that the relationship of the modified TAM model with its variables is positively significant, while the analysis of path relationship between model variables and outcomes from the questionnaire shows that it motivates learners to use Wi‐Fi‐BCD.

Research on Reliability Life Evaluation of Torque Motor based on Performance Degradation

The torque motor problem of reliability. The reliability evaluation of torque motor under the condition of accelerated degradation test is studied. Firstly, the failure mechanism of torque motor is studied, the performance degradation parameters are determined, then the theory of accelerated degradation test is described, the type of accelerated degradation model and the conditions of accelerated test are described. The method and procedure of product reliability analysis using accelerated degradation trajectory method under accelerated degradation test are studied. Finally, the reliability of a torque motor is evaluated and the average life value above 0.9 is calculated