Probabilistic Analysis Approach Research Articles

Ground-penetrating radar method used for the characterisation of ornamental stone quarries

In the work non-destructive ground-penetrating radar (GPR) was used to probe the texture and presence of anisotropies in different types of carbonated rocks intended for ornamental use.First, GPR on the different facies of a marble quarry in Macael (Almería, Spain) was applied where alternating layers of marble and mica schists can be found. GPR allows for the differentiation of the marble units from the mica schist units, which makes GPR a good tool for indirectly evaluating the reserves in a deposit. In addition, it allows for the detection of the different anisotropies in the marble units (holes, fractures), and this information could be utilised to formulate a work-plan design. Antennae of different frequencies were employed (100, 250 and 800MHz) for these purposes, and the 250MHz antenna had the most effective probing capacity for obtaining an accurate depth resolution.Second, a GPR study was conducted in three types of rock known commercially as Macael Marble, Crema Marfil and Red Travertine before the block-cutting process. For this configuration, the 800MHz antenna was used to differentiate the textures of each type of rock as well as the location of a variety of anisotropies, and the results showed that GPR is an effective tool for evaluating the block quality, determining whether resins must be injected to consolidate the block and estimating the orientation of the cutting process.In the work, the use of a supervised two-dimensional (i.e., radargram) probabilistic latent component analysis (PLCA) approach is proposed to highlight only the information from target objects (i.e., marble anisotropy) provided by the radargram, which facilitates the data interpretation by the user. This approach can search activations of the georadar pulse across both dimensions. Once the analysis has been performed, a variable-gain compensation process is proposed to outperform the energy losses that result from the reflections of the signal when a different material is found.The results have shown that the GPR method can be utilised as a tool for the diagnosis of stone materials prior to their use in artistic work or monuments; therefore, GPR may be considered a technique for material selection. The presence of discontinuities (sometimes visible to the naked eye) explain many of the phenomena and typologies of the stone after its eventual alteration, and such discontinuities could be avoided by means of this pre-emptive work.

Research on Probabilistic Safety Analysis Approach of Flight Control System Based on Bayesian Network

Traditional probabilistic safety analysis methods are not suitable for modern flight control system with multi-state probability. In this papera Bayesian Network based probabilistic safety model is built according to the state relationship between flight control system and its constituting components. A safety probability algorithm is proposed by using Universal Generating Function (UGF) combined with Clique Tree Propagation. The probability of system top failure condition and the importance of each constituting component are acquired efficiently, the safety level of the flight control system can be assed and the role of each component in the system safety can be determined. The probabilistic safety analysis approach based on Bayesian Network provide a simple and intuitive measure to deal with the safety analysis of flight control system with multi-state property, which overcome the deficiencies of traditional approach.

Flows of engineered nanomaterials through the recycling process in Switzerland

The use of engineered nanomaterials (ENMs) in diverse applications has increased during the last years and this will likely continue in the near future. As the number of applications increase, more and more waste with nanomaterials will be generated. A portion of this waste will enter the recycling system, for example, in electronic products, textiles and construction materials. The fate of these materials during and after the waste management and recycling operations is poorly understood. The aim of this work is to model the flows of nano-TiO2, nano-ZnO, nano-Ag and CNT in the recycling system in Switzerland. The basis for this study is published information on the ENMs flows on the Swiss system. We developed a method to assess their flow after recycling. To incorporate the uncertainties inherent to the limited information available, we applied a probabilistic material flow analysis approach. The results show that the recycling processes does not result in significant further propagation of nanomaterials into new products. Instead, the largest proportion will flow as waste that can subsequently be properly handled in incineration plants or landfills. Smaller fractions of ENMs will be eliminated or end up in materials that are sent abroad to undergo further recovery processes. Only a reduced amount of ENMs will flow back to the productive process of the economy in a limited number of sectors. Overall, the results suggest that risk assessment during recycling should focus on occupational exposure, release of ENMs in landfills and incineration plants, and toxicity assessment in a small number of recycled inputs.

Finite element model with imposed slip surfaces for earth mass safety evaluation

The study of earth masses requires numerical methods that provide the quantification of the safety factor without requiring detrimental assumptions. For that, equilibrium analysis can perform fast computations but require assumptions that limit its potentiality. Limit analysis does not require detrimental assumptions but are numerically demanding. This work provides a new approach that combines the advantage of both the equilibrium method and the limit analysis. The defined hybrid model allows probabilistic analysis and optimization approaches without the assumption of interslice forces. It is compared with a published case and used to perform probabilistic studies in both a homogeneous and a layered foundation. Analyses show that the shape of the density probability functions is highly relevant when computing the probability of failure, and soil elasticity hardly affects the safety of factor of the earth mass.

A probabilistic approach for landslide hazard analysis

We present a general framework for probabilistic landslide hazard analysis. With respect to other quantitative hazard assessment approaches, this probabilistic landslide hazard analysis has the advantage to provide hazard curves and maps, and to be applicable to all typologies of landslides, if necessary accounting for both their onset and transit probability.The method quantifies, for a given slope location, the exceedance probability of being affected by a landslide with a specific local intensity within a reference time interval, i.e. the hazard curve, under the common assumption that landslides behave as a Poisson process. Hazard maps are calculated, reducing the hazard curve to single values by choosing a fixed probability of exceedance following standards or regulation requirements. The method is based on the assessment of a landslide onset frequency, a runout frequency for long-runout landslides, and the local definition of landslide intensity, which can be expressed through different parameters, according to landslide typology. For long runout landslides, the runout and spatially-varying intensity and uncertainty are considered.Hazard curves and maps play a fundamental role in the design and dimensioning of mitigation structures, in land planning and in the definition of risk and hazard management policies. Starting from the general framework, we apply the methodology for rockfall hazard analysis, and we test it in an area affected by the Christchurch 2011 earthquake, New Zealand, which triggered a large number of rockfalls, killing five people.

Pervasive Knowledge Discovery by Just-in-Time Learning to Solve Simultaneous Data Reconciliation and Parameter Estimation of Industrial Processes

Reliable and accurate estimations from process measurements are crucial for achieving high-quality real-time optimization and process control. Data reconciliation and parameter estimation (DRPE) are important components for improving the performance of the control system. However, in practice, the operating conditions of industrial processes usually switch from one to another; process model parameters generally change with different process operations. Thus, DRPE problems should be solved repeatedly and quickly to avoid applications using out-of-date models. An efficient method for solving simultaneous DRPE problems, called just-in-time learning-based DRPE (JITL-DRPE), is proposed. JITL-DRPE uses the probabilistic analysis approach to discover relevant knowledge resources from past operating conditions. This is autonomous information extracted from past knowledge to proactively find appropriate initial guesses for the current operating condition to improve the convergence and accelerate the computation in solving simultaneous DRPE problems. JITL-DRPE is compared with the traditional DRPE method through applications to the air separation process and the free-radical polymerization of styrene. The results show that JITL-DRPE outperforms the traditional DRPE method in terms of the solution time, the number of iterations, and the percentage of successful optimizations.

생애 위험도기반 건축물의 설계단계 생애주기비용 분석 방법

LCC 분석은 건축물의 설계단계 뿐만 아니라 유지관리 단계에서의 보수 보강 또는 교체에 대한 최적 의사결정의 도구로서 이론적으로나 실무적으로 각광을 받고 있는 분석 방법이다. 이는 초기 투자비용의 효율성을 극대화 하고 유지관리를 통한 구조물 사용성의 효율적 증대를 극대화하는 노력의 일환으로 최근 건축물의 설계 및 유지관리 시 LCC 분석효과의 실질적인 적용이 요구되어 지고 있다. 따라서 본 논문은 일반적인 분석기법에 그치고 있는 기존 LCC 연구를 생애위험도를 고려한 LCC분석을 통해 설계단계 최적 의사결정을 위한 새로운 분석 방법론을 도출하였다. Recently, the demand on the practical application of life-cycle cost effectiveness for design and rehabilitation of structure is rapidly growing unprecedently in engineering practice. Accordingly, in the 21st century, it is almost obvious that life-cycle cost together with value engineering will become a new paradigm for all engineering decision problems in practice. However, in spite of impressive progress in the researches on the LCC, the most researches have only focused on the Deterministic or Probabilistic LCC analysis approach (Level-1 LCC Model) at design stage. Thus, the goal of this study is to develop a practical and realistic methodology for the Lifetime risk based Life-Cycle Cost (LCC)-effective optimum decision-making at design stage.

Probabilistic slope stability analysis by risk aggregation

This paper develops a probabilistic slope stability analysis approach that formulates the slope failure event as a series of mutually exclusive and collectively exhaustive events using conditional probability and utilizes Monte Carlo Simulation (MCS) to determine the occurrence probability for each of the mutually exclusive and collectively exhaustive events in a progressive manner. Then, these probabilities are aggregated to represent the overall slope failure probability pf. Equations are derived for the proposed approach, and the implementation procedures are illustrated using a cohesive slope example. The pf values obtained from the proposed approach are shown to agree well with those pf values that have been obtained by searching a large number of potential slip surfaces for the minimum factor of safety (FS) in each MCS sample. The computational time, however, is shown to reduce by, at least, an order of magnitude. In addition, a sensitivity study is performed to explore the effect of a key parameter in the proposed approach, i.e., the correlation coefficient threshold ρ0, on both the accuracy of pf and computational cost. When the spatial variability is significant, the effect of ρ0 on the accuracy of pf is significant, and a relatively large ρ0 value is needed to ensure the accuracy of pf. On the other hand, the computational time reduces substantially as the ρ0 value decreases. At an extreme case of ρ0=1.0, the risk aggregation approach becomes equivalent to an approach where a large number of potential slip surfaces are searched for the minimum FS in each MCS sample. In contrast, at the other extreme case of ρ0=0, the risk aggregation approach is the same as an approach that has been used in many previous studies and relies on only one slip surface. The risk aggregation approach deals rationally with the possibility of slope failure along more than one distinct slip surface (i.e., multiple failure modes) with significantly reduced computational efforts.

일본 서부 단층 지진원을 고려한 확률론적 지진해일 재해도 분석의 파고 변수 도출

Probabilistic tsunami hazard analysis (PTHA) is based on the approach of probabilistic seismic hazard analysis (PSHA) which is performed using various seismotectonic models and ground-motion prediction equations. The major difference between PTHA and PSHA is that PTHA requires the wave parameters of tsunami. The wave parameters can be estimated from tsunami propagation analysis. Therefore, a tsunami simulation analysis was conducted for the purpose of evaluating the wave parameters required for the PTHA of Uljin nuclear power plant (NPP) site. The tsunamigenic fault sources in the western part of Japan were chosen for the analysis. The wave heights for 80 rupture scenarios were numerically simulated. The synthetic tsunami waveforms were obtained around the Uljin NPP site. The results show that the wave heights are closely related with the location of the fault sources and the associated potential earthquake magnitudes. These wave parameters can be used as input data for the future PTHA study of the Uljin NPP site.

GIS와 확률론적 해석 기법을 기반으로 한 평면파괴의 운동학적 안정성 해석

암반으로 구성된 사면의 안정성은 암반 내에 포함되어 있는 불연속면의 방향과 강도 특성에 의해 좌우된다. 특히 암반사면의 안정성에 영향을 미치는 중요한 요인은 암반 내 불연속면의 방향과 사면 방향의 상대적 위치로 운동학적 분석에서는 이러한 사면의 방향성과 불연속면의 방향의 상대적 위치를 고려하여 사면 붕괴의 발생 여부를 판단한다. 기존의 운동학적 분석은 사면의 대표적인 방향을 먼저 결정하고 사면내에 분포하는 대표적인 불연속면의 방향성과의 비교를 통해 사면에서의 파괴 발생 여부를 평가하는 방식으로 수행되어왔다. 그러나 사면의 대표적인 방향성만을 이용하여 운동학적 분석을 수행하는 경우 사면 내에서 발생하는 사면 방향의 변화를 분석에 고려하지 못하는 문제점을 가지고 있다. 또한 불연속면 방향의 경우 불확실성에 의해 동일한 불연속면군에 속한 불연속면이라도 분산이 커지는 문제점을 가지고 있다. 따라서 본 연구에서는 이를 보완하기 위하여 수치지형도를 이용하여 사면을 여러 개의 cell로 구분하고 각 cell에서 사면의 경사방향과 경사를 획득하였다. 그리고 각 cell의 사면 방향을 불연속면의 방향성과 비교하여 각 cell에서의 평면파괴에 대한 운동학적 분석을 수행하였다. 또한 불연속면 방향성에 개입된 불확실성을 고려하기 위하여 불연속면의 경사와 경사방향을 확률변수로 선정하고 몬테카를로 시뮬레이션을 활용하여 확률론적 해석을 수행하였다. 본 연구에서는 제안된 해석기법의 적정성을 파악하기 위하여 급경사지의 사면이 분포하고 있는 강원도 춘천시 관내 배후령길을 대상으로 분석을 수행하였다. The stability of rock slope is mainly controlled by the orientation and shear strength of discontinuties in rock mass. Therefore, in kinematic analysis, the orientation of the combination of discontinuities and slope face is examined to determine if certain modes of failure can be occurred. In previous kinematic analysis, a representative orientation of the slope face and mean orientation of discontinuity set were used as input parameters. However, since the orientations of slope face varies according to locations of measurement, the representative slope face orientation could cause misunderstanding for kinematic instability. In addition, since the orientations of each discontinuity are scattered in the same discontinuity set, there is the possibility that uncertainties are involved in the procedure of kinematic analysis. Therefore, in this study, the detailed digital topographic map was used to obtain the orientation of slope face. In addition, the probabilistic analysis approach was utilized to deal properly with the uncertainties in discontinuity orientation. The proposed approach was applied to steep slopes in mountain road located in Baehuryeong, Chunncheon city, Gangwon-Do. The analysis results obtained from the deterministic and probabilistic analysis were compared to check the feasibility of proposed the analysis.

Improving short utterance i-vector speaker verification using utterance variance modelling and compensation techniques

This paper proposes techniques to improve the performance of i-vector based speaker verification systems when only short utterances are available. Short-length utterance i-vectors vary with speaker, session variations, and the phonetic content of the utterance. Well established methods such as linear discriminant analysis (LDA), source-normalized LDA (SN-LDA) and within-class covariance normalization (WCCN) exist for compensating the session variation but we have identified the variability introduced by phonetic content due to utterance variation as an additional source of degradation when short-duration utterances are used. To compensate for utterance variations in short i-vector speaker verification systems using cosine similarity scoring (CSS), we have introduced a short utterance variance normalization (SUVN) technique and a short utterance variance (SUV) modelling approach at the i-vector feature level. A combination of SUVN with LDA and SN-LDA is proposed to compensate the session and utterance variations and is shown to provide improvement in performance over the traditional approach of using LDA and/or SN-LDA followed by WCCN. An alternative approach is also introduced using probabilistic linear discriminant analysis (PLDA) approach to directly model the SUV. The combination of SUVN, LDA and SN-LDA followed by SUV PLDA modelling provides an improvement over the baseline PLDA approach. We also show that for this combination of techniques, the utterance variation information needs to be artificially added to full-length i-vectors for PLDA modelling.

Stability of mine development intersections — a probabilistic analysis approach

Mine developments, such as haulage drifts, cross-cuts, and intersections, are the only way to access valuable ore from mining zones; they link mine developments with the nearest ore access points. Thus, they must remain stable throughout their service life or production plan. Mine development instability can cause production delay, loss of reserves, as well as damage to equipment and injury to miners. This paper presents a stepwise methodology to assess the stability of mine development intersections with respect to the mine production plan. A case study, the #1 Shear East orebody at Vale Garson Mine in Sudbury, Ontario, is presented. A three-dimensional, elastoplastic, finite difference model (FLAC 3D) is created to simulate the development of an intersection situated 1.5 km below ground surface. The unsatisfactory performance of the intersection is evaluated in terms of strength-to-stress ratio with respect to mining sequence. A failure criterion is defined by a minimum strength-to-stress ratio of 1.4, and is used for mine developments (temporary openings). The intersection stability is evaluated at various mining stages and the modified “point-estimate method” (PEM) of (2n2 + 1) is then invoked to study the probability of drift instability at the intersection. The results are presented and categorized with respect to probability, instability, and mining stage.

Probabilistic seismic hazard assessment of Himachal Pradesh and adjoining regions

Seismically active Himachal Pradesh and adjoining regions comprising Himalayan orogenic belt with the experience of the great Kangra earthquake of 1905, has high potential for river valley projects. There are already operating hydropower projects, some under construction and a few more coming up. In view of this it is important to know the ground motion nature for various locales. The present study is about estimation of Peak Ground Acceleration (PGA) for the state of Himachal Pradesh and adjoining regions using probabilistic seismic hazard analysis (PSHA) approach. Standard procedure for PSHA has been adopted for this study and peak ground motion has been estimated for 10% and 2% probability of exceedance in 50 years at the bed rock level considering two cases: (i) varying b-value for each source zone, (ii) constant b-value for each source zone. For 10% probability of exceedance in 50 years, the PGA values vary from 0.096 to 0.15 g and 0.09 to 0.26 g considering varying b-value, and constant b-value, respectively. In case of 2% probability of exceedance in 50 years, the PGA varies between 0.07 to 0.24 g considering varying b-values and 0.14 to 0.37 g considering constant b-values. Higher PGA values are observed in the southeast part considering varying b-values whereas the region situated around Kaurik Fault System (KFS) has shown higher PGA values in case of constant b-value.

Probabilistic approach for epistemic analysis of lake tapping of koyna dam for future forecasting

The statistical technique like confidence interval (CI) is used to determine the confidence limits of water head over lake tapping site of Koyna Dam (India, Maharashtra) from water level data taken from government of Maharashtra 2000-2010, which helps in future forecasting. It is the statistical technique which gives the Probable Value of the water head in the relative month. By studying these probable values of water heads, monthly variation in the heads seasonal variation can be achieved. Contour maps and variograms are studied to check the variation of Water head from year-2000-2010. It also helps to determine the probable nature by knowing the confidence Interval of heads and it is more useful and helpful for the water management of rain water which is accumulated on ground by the means of large reservoirs. Predication of rainfall and head variation is achieved.

Study of methods for evaluating the probability of multiple site damage occurrences

Two methods currently available for evaluating the probability of Multiple Site Damage (MSD) occurrence were studied in this paper. One of the methods is a probabilistic analysis approach based on the statistical theory and fatigue characteristics of each structural detail, and the other is an approach which defines the initial damage scenario by means of Monte-Carlo simulation, and multiple initial crack scenarios are randomly generated. A modified method based on the Monte-Carlo simulation was proposed in this paper, in which the random fluctuation of the stress was considered to give more accurate evaluation results. In the presented method, the probability of MSD occurrence in a structural element containing multiple details was calculated based on the Monte-Carlo simulation and the p-S-N curve of a single structural detail. Fatigue tests were accomplished using specimens containing 21-similar-details to obtain the fatigue life corresponding to MSD occurrence. Tests on single-detail specimens and static calibration tests were also conducted to get the basic fatigue properties of the material and the degree of stress fluctuation. The aforementioned three methods were compared and validated via the test results. The influence of the stress random fluctuation degree on the probability of MSD occurrence and influence of the distribution types on evaluating the MSD occurrence probability were discussed. Multiple Site Damage (MSD), fatigue crack initiation, probability, stress fluctuation

A collision-allowed approach for probabilistic assessment of riser interference

Riser interference assessment is especially crucial in deep water, as the compliancy of risers generally increases with length. This paper presents a probabilistic approach for riser interference analysis, taking into account the stochastic nature of the wave forces. The methodology is founded on the collision-allowed principle, in which infrequent collisions are permitted, provided that structural integrity is not compromised. The collision analysis is traditionally separated into the local and global stages. The procedure for local impact analysis is well established in the literature. For the global analysis, one challenge aspect is that very few collisions, if any, can be observed in a simulation of a practical duration. This difficulty is herein addressed by extrapolating the pre-collision response characteristics to predict the statistics of the critical collision parameters such as impact velocity and kissing angle. This task is made complicated by significant nonlinearities in the loads and responses. The results of the global and local analyses are subsequently combined to evaluate the yield and fatigue limit states. The proposed approach is implemented on a top-tensioned riser system, and it is found to yield good estimates of the system reliability, based on comparison with extensive Monte Carlo simulations.

Effect of computer-generated turbulent wind field on trajectory of compact debris: A probabilistic analysis approach

A model and numerical algorithm is developed to simulate wind-borne debris trajectories in a fully-developed atmospheric boundary layer wind. The model works in two dimensions and makes use of synthetically-generated turbulence time histories; it accounts for variable mean velocity field with elevation and turbulence. The simulation of a partially coherent wind field was based on the wave superposition method (Di Paola, 1998) [1]. For the simulation of the turbulence field, a simplified approach is proposed. First, turbulence is generated at discrete points located on the “inlet boundary” of the field; second, turbulence is propagated through the field using either Taylor’s “frozen turbulence” hypothesis or a simplified “Eulerian–Lagrangian” formulation. The latter term is used to emphasize that an expression is employed to approximately replicate the features of the Lagrangian turbulence wind spectrum (for high-speed moving objects), even though turbulence is still synthetically generated on a large portion of the field at all times, from an Eulerian point of view. After generating the wind field, the trajectory of compact objects is estimated by means of a point mass dynamic model, converted to state-space form and integrated by fifth-order Runge–Kutta method.The numerical model is applied to the study of the risk of impact by wind-borne debris against tall building facades, recently investigated by the authors for uniform non-turbulent wind field only. The analysis is conducted by using the computer-generated wind field to estimate “universal probability curves” (probability-of-impact curves) for compact debris, conditional on the initial distance of the object from the building before takeoff. Both qualitative and quantitative variations are noted in comparison with previous results.

Probabilistic and deterministic soil structure interaction analysis including ground motion incoherency effects

Soil-structure interaction (SSI) is a major step for seismic design of massive and stiff structures typical of the nuclear facilities and civil infrastructures such as tunnels, underground stations, dams and lock head structures. Currently most SSI analyses are performed deterministically, incorporating limited range of variation in soil and structural properties and without consideration of the ground motion incoherency effects. This often leads to overestimation of the seismic response particularly the In-Structure-Response Spectra (ISRS) with significant impositions of design and equipment qualification costs, especially in the case of high-frequency sensitive equipment at stiff soil or rock sites. The reluctance to incorporate a more comprehensive probabilistic approach is mainly due to the fact that the computational cost of performing probabilistic SSI analysis even without incoherency function considerations has been prohibitive. As such, bounding deterministic approaches have been preferred by the industry and accepted by the regulatory agencies. However, given the recently available and growing computing capabilities, the need for a probabilistic-based approach to the SSI analysis is becoming clear with the advances in performance-based engineering and the utilization of fragility analysis in the decision making process whether by the owners or the regulatory agencies.This paper demonstrates the use of both probabilistic and deterministic SSI analysis techniques to identify important engineering demand parameters in the structure. A typical nuclear industry structure is used as an example for this study. The system is analyzed for two different site conditions: rock and deep soil. Both deterministic and probabilistic SSI analysis approaches are performed, using the program SASSI, with and without ground motion incoherency considerations. In both approaches, the analysis begins at the hard rock level using the low frequency and high frequency hard rock input motions obtained from Probabilistic Seismic Hazard Analysis (PSHA) and the site response analysis is conducted with simulated soil profiles and accompanying soil nonlinearity curves. The deterministic approach utilizes three strain-compatible soil profiles (Lower Bound (LB), Best Estimate (BE) and Upper Bound (UB)) determined based on the variation of strain-compatible soil profiles obtained from the probabilistic site response analysis and uses SSI analysis to determine a conservative estimate of the required response as the envelope of the SSI results from LB, BE and UB soil cases. In contrast, the probabilistic SSI analysis propagates the uncertainty in the soil and structural properties and provides rigorous estimates for the statistical distribution of the response parameters of interest. The engineering demand parameters considered are the story drifts and ISRS at key locations in the example structure. The results from the deterministic and probabilistic approaches, with and without ground motion incoherency effects, are compared and discussed. Recommendations are made regarding the efficient use of statistical methods in probabilistic SSI analysis and the use of such results in Integrated Soil-Structure Fragility Analysis (ISSFA) and performance-based design.

A probabilistic approach for safety risk analysis in metro construction

This paper presents a probabilistic decision approach for safety risk analysis for metro construction in complex project environments. An expert confidence index is proposed for the fuzzy probability estimation of basic events, aiming to ensure the reliability of collected data during the expert investigation. An approach for defuzzification is developed in a precise way based on the representation theorem, attempting to overcome the limitations related to fuzzy linear approximations. A sensitivity analysis technique is utilized to evaluate the percentage contribution of the basic events to the failure of a top-event. A possibility based importance index, fuzzy importance measure, is deployed for the sensitivity analysis of basic event to reveal the critical basic events for reducing the risk limit. A typical hazard in tunnel cross passage construction (TCPC) on the example of Wuhan Yangtze Metro Tunnel construction is presented in a case study. The results demonstrate the feasibility of the proposed method and its application potential. The proposed method can be used as a decision support tool to provide guidelines for safety management in metro construction, and thus increase the likelihood of a successful project in a complex environment.

Optimal condition-based maintenance decisions for systems with dependent stochastic degradation of components

Components in engineered systems are subjected to stochastic deterioration due to the operating environmental conditions, and the uncertainty in material properties. The components need to be inspected and possibly replaced based on preventive or failure replacement criteria to provide the intended and safe operation of the system. In the present study, we investigate the influence of dependent stochastic degradation of multiple components on the optimal maintenance decisions. We use copula to model the dependent stochastic degradation of components, and formulate the optimal decision problem based on the minimum expected cost rule and the stochastic dominance rules. The latter is used to cope with decision maker's risk attitude. We illustrate the developed probabilistic analysis approach and the influence of the dependency of the stochastic degradation on the preferred decisions through numerical examples.