Probability Of Serviceability Failure Research Articles

Spectral Analysis of a Sagged Cable with an Optimal Viscous Inertial Mass Damper under Random Wind in a Generalized State-Space Formulation

In this study, a spectral analysis method is proposed for a sagged cable with an optimal viscous inertial mass damper (VIMD) under random wind loads based on a generalized state-space formulation. The frequency response functions of the cable responses were evaluated for the wind force vector using complex modes orthogonal to the system matrices, from which the power spectral densities of the cable responses were readily obtained for the spectral matrix of the wind force. The accuracy and efficiency of the proposed method were verified by comparing the root mean square responses with those obtained from the time-domain and covariance analyses. The performance of two VIMDs optimized by the fixed-point method and the maximum damping ratio method was investigated for various cases of cable sag and wind properties. Serviceability failure probability analysis was also conducted using the first-passage problem. The results show that the proposed spectral method is computationally more efficient than the other two analysis methods. The VIMDs optimized for the first original cable mode were found to be highly effective in reducing cable vibration and the probability of serviceability failure.

Methodology for Assessing Shortened ILS LOC and GP Critical Areas: an Example of Gorno-Altaisk Aerodrome

Based on the analysis of recommendations of the International Civil Aviation Organization on a reasonable reduction in sizes of ILS critical areas and identification of shortcomings of the existing requirements of the Russian Federal Aviation Regulations for critical areas of ILS localiser and glide path (glide slope), a procedure has been developed that allows assessment localiser and glide slope bends for shortened critical areas. The assessment comprises the influence of different reflecting objects situated on operation area of the aerodrome, as well as of aerodrome environs on the operation of the ILS localiser and glide path.Reflecting objects can be approximated by models of a wall (that simulates reflections from buildings, bridges, fences), of a cylinder (that simulates reflections from factory pipes, tanks, containers, aircraft fuselages) and of a hemispherical diffuse reflector (simulates reflection from elevated terrain).The procedure was tested for Gorno-Altaisk aerodrome, and aproposal was developed to reduce the critical area of the localiser, which will expand the apron by 35 m, eliminate problems with imposed speed limits and blocking movement of aircraft on the taxiway. Also, the probability of service failure will decrease by 3…11 times, and the runway occupancy time will decrease by 12,5…26 % compared to existing features.

Principles of developing a limited-queue mass service system on the .NET platform

The paper is the result of the thorough research aimed at studying the principles of creation, modeling and practical use of queue-limited mass service systems (MSS) based on the .NET technology platform and implemented using the C# programming language. In the course of the paper, special attention is paid to both single-channel and multi-channel systems. In the introductory part of the article the fundamental concepts of the theory of mass service are considered. The basic characteristics of systems, such as fixed queue length systems, single-channel and multi-channel systems with probability of service failure, systems with unlimited and limited wait times, closed systems, and multi-channel systems with channel-to-channel interaction, are discussed. Detailed examples of C# code are presented to illustrate the class structures used to model both single-channel and multi-channel MSS. Specific scenarios for the use of the presented structures within the framework of MSS modeling are considered. The paper highlights the practical application of mass service systems in solving real-world problems. Using examples from banking and traffic management in telecommunications, it is demonstrated how MSS can contribute to optimizing waiting times and efficient resource management. Prospects for further research in the field of mass service systems are suggested. Given the importance of MSS in various industries such as banking, telecommunications, logistics and many others, the high relevance of the topic is due to the need to find new approaches and methods to improve the efficiency and optimization of these systems. In general, the article is a valuable research material for specialists involved in modeling and practical application of mass service systems.

Collaborative edge computing for distributed CNN inference acceleration using receptive field-based segmentation

This paper studies inference acceleration using distributed CNNs in collaborative edge computing network. To ensure no inference accuracy loss in task partitioning, we propose receptive field-based segmentation. To reduce the computation time and communication overhead, we propose a novel collaborative edge computing using fused-layer parallelization to partition a CNN model into multiple blocks. To find the optimal partition of a CNN model, we use dynamic programming, named as DPFP. To address computation heterogeneity of edge servers (ESs), we design a low-complexity search algorithm which can select the optimal subset of collaborative ESs for inference. The experimental results show that DPFP can accelerate inference up to 71% for ResNet-50 and 73% for VGG-16 compared to running the pre-trained models, which outperforms the existing works MoDNN and DeepSlicing. Moreover, we propose an analytical method to estimate the speedup ratio of different GPU platforms by using FLOPs and effective computing capacity. Furthermore, we evaluate the service failure probability under time-variant channel and variation of image sizes, which shows that DPFP is effective to ensure high service reliability with strict service deadline.

The impact of predicted quality and customer cost on quality assurance behavior

PurposeBased on cost of quality (CoQ) research, this study aims to highlight the importance of incorporating the costs to customers in contributing to service quality when examining how customers respond to possible service failures [quality assurance behavior (QAB)]. Consequently, this study also aims to show how the CoQ framework can be a useful tool to the service industry in determining enhancements in quality and related expenditures.Design/methodology/approachUsing the airline industry as a case example, this study empirically tests the impact of predicted service quality and its associated costs on an individual’s QAB (wait time spent at the departing airport) through revealed preferences. The study uses survey data from more than 4,000 passengers matched with travel-specific quality information archived by the US Department of Transportation (DOT).FindingsThis study finds that customers are willing to increase their level of QAB when informed of an increased probability of service failure. This study also finds that the level of QAB varies depending on anticipated customer costs of avoiding or responding to service failures.Practical implicationsFindings of this study emphasize the need for shared responsibility between service providers and their customers in making decisions on the provision of service quality, as helping customers adjust the appropriate level of QAB may result in greater efficiency and higher quality of service.Originality/valueThis study conceptualizes and empirically tests causal relationships between expected quality and customer efforts (QAB), thus contributing to operations literature examining CoQ in a service setting. This study argues that it is critical to consider shared responsibilities between co-producers (service providers and customers) in service operations studies.

Quality assessment of the contact center while implementation the IP IVR system by using teletraffic theory

The paper considers the form of taking into account the specialization of information needs. An analysis of the work of modern call centers has been carried out. The authors noted the effectiveness of using IVR devices, operators, and consultants for differentiated customer service and the need to take feedback into account when forming the revenue stream of applications. The models make it possible to determine the leading indicators of the quality of service for applications arriving at the call center. Formal expressions for descriptions are derived from the input parameters' values and the model's stationary probability. The relationships between the characteristics of the call center that regulate the intensity of incoming and outgoing calls, call processing through 3CXPhone, corporate mail, and social networks were obtained using Global Statistic. The developed methodology for organizing information and reference systems makes it possible to consider modern trends in the development of call centers. The paper presents the results of research using the IP IVR system. The results of calculating service characteristics are given for two different types of calls with mixed order ω=(0.5; 0.7; 0.9). The presented results were obtained by using experimental data of the JSC Kazakhtelecom's call center. For the calculations, the authors used the formulas of the teletraffic theory for a mixed service system. It also assesses the extent of combined service model effects for the contact center's call quality. It is shown that the probability of lost calls depends on the incoming load. The obtained results show that the mixed order for incoming calls servicing affects the probability of service failure.

Probability of serviceability failure in cement-stabilized soft clay excavation

The probabilities of exceedance of the maximum tensile stress in cement-stabilized soft clay, the displacement of retaining structure and bottom upheave are explored with deterministic finite element method and fuzzy finite element approach (FFEA) for a Shanghai pit excavation. Effect of the scale of fluctuation on the probability of exceedance is clearly observed. In the cases with an infinite scale of fluctuation, on account of the asymmetrical configuration of resulting fuzzy number, the probability of exceeding the threshold of the maximum tensile stress is comparatively low and will result in an unsafe design; however, the probability of exceeding the threshold of the displacement of the cement-reinforced soft clay and tunnel are a bit higher, which will consequently lead to a conservative design. For smaller threshold, the scenario with a smaller scale of fluctuation yields a higher probability of exceedance, and the trend reverses when relatively larger threshold is adopted.

Serviceability Assessment Method of Stay Cables with Vibration Control Using First-Passage Probability

As the construction of long-span bridges such as cable-stayed bridges increases worldwide, maintaining bridge serviceability and operability has become an important issue in civil engineering. The stay cable is a principal component of cable-stayed bridges and is generally lightly damped and intrinsically vulnerable to vibration. Excessive vibrations in stay cables can potentially cause long-term fatigue accumulation and serviceability issues. Previous studies have mainly focused on the mitigation of cable vibration within an acceptable operational level, while little attention has been paid to the quantitative assessment of serviceability enhancement provided by vibration control. This study accordingly proposed and evaluated a serviceability assessment method for stay cables equipped with vibration control. Cable serviceability failure was defined according to the range of acceptable cable responses provided in most bridge design codes. The cable serviceability failure probability was then determined by means of the first-passage problem using VanMarcke’s approximation. The proposed approach effectively allows the probability of serviceability failure to be calculated depending on the properties of any installed vibration control method. To demonstrate the proposed method, the stay cables of the Second Jindo Bridge in South Korea were evaluated and the analysis results accurately reflected cable behavior during a known wind event and show that the appropriate selection of vibration control method and properties can effectively reduce the probability of serviceability failure.

Time-variant reliability of timber beams according to Eurocodes considering long-term deflections

ABSTRACT In order to achieve a consistent level of failure probability, structural design codes are optimized using probabilistic methods. This optimization process traditionally focuses on the ultimate limit states (ULS). However, in the design of timber structures the performance of the structural members is often governed by the serviceability limit state (SLS) associated with different load levels than applied in the ULS. The probability of serviceability failure is strongly dependent on the loading sequence and the time-dependent response of timber; therefore, a time-variant probabilistic model is recommended to estimate them properly. This study aims to investigate the time-dependent reliability for long-term deflections of timber office and residential floor beams according to the specifications of the Eurocodes. A simple creep model is used to calculate the deflections and Monte Carlo simulation is carried out to determine the reliability index. It was found that the creep factor and the suggested deflection limits given in Eurocode 5 might not be appropriate to achieve the expected target reliabilities. To obtain a more consistent reliability, more suitable values for the mentioned parameters were suggested. However, the primary aim was to present a framework to determine appropriate deflection limits for structural codes.

Code-Partitioning Offloading Schemes in Mobile Edge Computing for Augmented Reality

Augmented reality (AR) is one of the emerging use cases relying on ultra-reliable and low-latency communications (uRLLC). The AR service is composed of multiple dependent computational-intensive components. Due to the limited capability of user equipment (UE), it is difficult to meet the stringent latency and reliability requirements of AR service merely by local processing. To solve the problem, it is viable to offload parts of the AR task to the network edge, i.e., mobile edge computing (MEC), which is expected to extend the computing capability of the UE. However, MEC also incurs extra communication latency and errors on the wireless channel; therefore, it is challenging to make an optimum offload decision. So far, a little of state-of-the-art work has considered both the latency and reliability of the MEC-enabled AR service. In this paper, we study the scenario multiple edge nodes cooperate to complete the AR task. The dependency of task components is modeled by a directed acyclic graph through code partitioning. We aim to minimize the service failure probability (SFP) of the MEC-enabled AR service considering reliability and latency. We design an integer particle swarm optimization (IPSO)-based algorithm. Although the solution of IPSO-based algorithm approaches the optimum of the problem, it is infeasible to use IPSO for real-time AR services in practice due to the relatively high computational complexity. Hence, we propose a heuristic algorithm, which achieves a performance close to that of the IPSO-based algorithm with much lower complexity. Compared with state-of-the-art work, the heuristic algorithm can significantly improve the probability to fulfill the targeted SFP in various network conditions. Due to the generic characteristics, the proposed heuristic algorithm is applicable for AR services, as well as for many other use cases in uRLLC.

Effect of spatial variability of soft clays on geotechnical design of braced excavations: A case study of Formosa excavation

This case study presents the effect of spatial variability of soft clays on the geotechnical serviceability assessment of braced excavations. Finite element modeling is performed to predict the excavation-induced wall and ground movement. The spatial variations in two key soil parameters are modeled as two correlated lognormal random fields. The system reliability-based serviceability assessment conducted in this case study shows that the system probability of serviceability failure is greater than or equal to that for each single failure mode, indicating that serviceability assessment considering an individual failure mode can result in unsafe predictions.

DISTRIBUTIONS OF MOE AND MOR IN A FULL LUMBER POPULATION

Reliability calculations for lumber products ultimately depend on the statistical distributions that we use to model lumber stiffness and strength. Fits of statistical distributions to empirical data allow researchers to estimate the probability of failure in service. For these fits to be useful, the theoretical statistical distributions must be good matches for the empirical lumber property populations. It has been common practice to assume that the MOE of a grade of lumber is well-fit by a normal distribution, and the MOR of a grade of lumber is well-fit by a normal, lognormal, or two-parameter Weibull distribution. Recent theoretical results and empirical tests have cast significant doubt on these assumptions. The exact implications of the theoretical results depend on the distributions of full (mill-run) MOE and MOR populations. Mill-run data have not yet appeared in the literature. Instead, studies have focused on subpopulations formed by visual or machine stress rated (MSR) grades of lumber. To better understand the implications of the recent theoretical results, we have investigated the statistical distributions of mill-run MOE and MOR data. An ungraded mill-run sample of 200 southern pine 24 s produced at a single mill on a single day was subjected to both nondestructive (transverse vibration and longitudinal stress wave) evaluation and static bending tests to determine its MOE and MOR values. Various distributions were fit to the MOE and MOR data and evaluated for goodness-of-fit. The results suggest that mill-run MOE might be adequately modeled by a normal distribution or a mixture of two normal distributions, mill-run MOR might be adequately modeled by a skew normal distribution or a mixture of two normals, and neither mill-run MOE nor mill-run MOR is well-fit by a Weibull distribution.

ОПТИМИЗАЦИЯ МАРКОВСКИХ СИСТЕМ МАССОВОГО ОБСЛУЖИВАНИЯ С ОЖИДАНИЕМ В СИСТЕМЕ MATLAB

The article focuses on attempt to optimize two well-known Markov systems of queueing: a multichannel queueing system with finite storage, and a multichannel queueing system with limited queue time. In the Markov queuing systems, the intensity of the input stream of requests (requirements, calls, customers, demands) is subject to the Poisson law of the probability distribution of the number of applications in the stream; the intensity of service, as well as the intensity of leaving the application queue is subject to exponential distribution. In a Poisson flow, the time intervals between requirements are subject to the exponential law of a continuous random variable. In the context of Markov queueing systems, there have been obtained significant results, which are expressed in the form of analytical dependencies. These dependencies are used for setting up and numerical solution of the problem stated. The probability of failure in service is taken as a task function; it should be minimized and depends on the intensity of input flow of requests, on the intensity of service, and on the intensity of requests leaving the queue. This, in turn, allows to calculate the maximum relative throughput of a given queuing system. The mentioned algorithm was realized in MATLAB system. The results obtained in the form of descriptive algorithms can be used for testing queueing model systems during peak (unchanged) loads.

Serviceability assessment and sensitivity analysis of cast iron water pipes under time-dependent deterioration using stochastic approaches

Research Article| September 28 2016 Serviceability assessment and sensitivity analysis of cast iron water pipes under time-dependent deterioration using stochastic approaches Mojtaba Mahmoodian; Mojtaba Mahmoodian 1School of Engineering, RMIT, Melbourne, Australia E-mail: mojtaba.mahmoodian@rmit.edu.au Search for other works by this author on: This Site PubMed Google Scholar Chun Qing Li Chun Qing Li 1School of Engineering, RMIT, Melbourne, Australia Search for other works by this author on: This Site PubMed Google Scholar Journal of Water Supply: Research and Technology-Aqua (2016) 65 (7): 530–540. https://doi.org/10.2166/aqua.2016.101 Article history Received: August 12 2015 Accepted: August 09 2016 Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Cite Icon Cite Permissions Search Site Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAll JournalsThis Journal Search Advanced Search Citation Mojtaba Mahmoodian, Chun Qing Li; Serviceability assessment and sensitivity analysis of cast iron water pipes under time-dependent deterioration using stochastic approaches. Journal of Water Supply: Research and Technology-Aqua 3 November 2016; 65 (7): 530–540. doi: https://doi.org/10.2166/aqua.2016.101 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex Determination of the depth of the corrosion pit is essential to predict the serviceability of corrosion affected pipes and to instigate maintenance and repairs for the pipeline system. In this paper, a reliability-based methodology for serviceability assessment of corrosion affected pipes is presented. The depth of corrosion pit is considered as the critical parameter that causes serviceability failure when it is greater than the wall thickness of the pipe. A stochastic model for corrosion depth of cast iron pipes is developed and a time-dependent method is employed to quantify the probability of serviceability failure so that the time for the pipeline to be unserviceable and hence requiring repairs can be determined. A sensitivity analysis is also undertaken to identify the factors that affect the failure due to corrosion. The methodology presented in this study can be used as a tool for infrastructure managers in different industries such as water distribution systems, oil and gas pipelines, sewer networks, etc. The methodology can help pipeline engineers and asset managers in making decisions with regard to the serviceability of corrosion affected pipelines both for assessment of existing systems and for designing new pipelines. cast iron pipes, corrosion pit, first passage probability, life time prediction, reliability analysis, serviceability failure © IWA Publishing 2016 You do not currently have access to this content.

Please explain why it happened! How perceived justice and customer involvement affect post co-recovery evaluations: A study of Iranian online shoppers

As online shopping is growing, the probability of service failure is increasing, too. Therefore, online retailers need to employ particular recovery strategies in online setting. Online shopping relies more on information and communication rather than traditional shopping. In addition, involving consumers in co-recovery procedure triggers them to perceive post-recovery satisfaction higher than usual, hence, resulting enhancement behavioral intentions (i.e. positive word-of-mouth, repurchase intention, loyalty, intention to future co-creation). While recent researches in online shopping did not examine the impact of informational justice and co-recovery, this study aims to investigate the influence of four justice dimensions (e.g. distributive, procedural, interactional and informational) by mediating role on involvement on post-recovery satisfaction. Thus, a scenario-based, between-subjects experiment was performed to reduce extreme memories and biases of the subject matter. A sample of 278 Iranian online shoppers from two shopping websites (i.e. Digikala and Bamilo) was employed to analyze data. Covariance-Based Structural Equation Modeling (CB-SEM) was employed to analyze data. First, the measurement model was performed to check validity and reliability of the constructs involved in the conceptual framework. Then, proposed hypotheses were tested using structural model. Results show that justice dimensions are positively associated with post-recovery satisfaction. Also, it is confirmed that involvement is mediator between justice dimensions and satisfaction, which means customers participation in recovery procedure is necessary in online post-recovery assessment. These findings also suggest that informational justice should be consider as a crucial factor in online shopping, particularly online recovery. Results suggest that managers should be generous to share information with customers and explain them what is the reason of failure, in detail. Finally, post-recovery satisfaction is positively related to behavioral intentions such as positive word of mouth, loyalty; repurchase intention and future co-creation tendency.

System probabilistic serviceability assessment of braced excavations in clays

The system probability of serviceability failure for braced excavations in clays is investigated in this paper. The serviceability assessment involves the potential damage to the adjacent infrastructures caused by the excessive wall deflection and the associated ground surface settlement. In this study, the finite element program of PLAXIS implemented with user-defined soil models is adopted as a tool to simulate the excavation-induced wall deflection and ground surface settlement. The performance functions for both wall deflection and ground surface settlement are constructed through response surface method (RSM). Depending on the limiting excavation-induced responses, the serviceability limit state (SLS) design can be realized through meeting the acceptable system reliability or the corresponding system probability of serviceability failure. A case study is presented herein to demonstrate the feasibility of the system reliability approach in the design of braced excavations.

Differentiated quality-of-protection provisioning with probabilistic-shared risk link group in survivable flexi-grid optical networks

A multilink failures model, i.e., probabilistic-shared risk link group (PSRLG), is adopted to investigate the problem of differentiated quality-of-protection (QoP) provisioning for flexi-grid optical networks. As a metric, service failure probability (SFP) is introduced to exactly examine the feasibility of differentiated QoP schemes, which denotes the failure probability of a connection during transmission. According to different reliability require- ments, connection requests are divided into three classes, i.e., class high, class middle, and class low. Then two differentiated QoP provisioning schemes are proposed based on the class division, i.e., intraclass-shared re- source scheme (ICSR scheme) and cross-class-shared resource scheme (CCSR scheme). The former allows a connection to share backup resources only with those connections in the same class, whereas the latter enables the connections in different classes to share backup resources. Simulation results show that our proposed schemes could well provide differentiated reliability with PSRLG constraint and achieve a good balance between reliability and resource efficiency. Moreover, the CCSR scheme achieves lower blocking probability, lower re- source redundancy, and higher spectrum utilization without sacrificing reliability compared to the ICSR scheme. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in

Cracking Risks, Durability, and Life-cycle Costs for RC Bridges Subject to Carbonation-induced Corrosion

AbstractBased on the corrected carbonation depth prediction model, this study develops a time-dependent structural reliability model to predict the probability of serviceability failure subject to carbonation-induced corrosion, using the latest time-dependent CO2 concentration data. Probabilistic methods are used significant uncertainty and variability of CO2 emissions, deterioration mechanisms, material properties, dimensions, and environments exist. The time-dependent structural reliability analysis will predict the probability of serviceability failure and cracking risks under various durability design specifications and crack widths considering several IPCC future atmospheric CO2 emission scenarios. Probabilistic life-cycle costs are developed to compare the economic performance of various durability design specifications and crack widths. An increase in design cover for concrete carbonation corrosion is presented. For cover=40 mm and water cement ratio=0.45, the risk of cracking is 0.003, and the ef...

Bootstrapping for Characterizing the Effect of Uncertainty in Sample Statistics for Braced Excavations

A simple procedure for assessing the probability of serviceability failure in a braced excavation involving bootstrapping to char- acterize the effect of uncertainty in sample statistics is presented. Here, the failure is defined when an excavation system's response in terms of themaximumwalldeflectionorgroundsettlementthatexceedsthelimitingvaluespecifiedbytheclientorinanapplicablecode.Theanalysisfor the probability of failure (or probability of exceedance) necessitates an evaluation of the means and SDs of critical soil parameters. In geotechnical practice,thesemeansandSDsareoftenestimatedfromaverylimiteddataset,whichcanleadtouncertaintyinthederivedsample statistics. Thus, in this study bootstrapping is used to characterize the uncertainty or variation of sample statistics and its effect on the failure probability.Throughthebootstrappinganalysis,theprobabilityofexceedancecanbepresentedasaconfidenceintervalinsteadofasingle, fixed probability.Theinformationgainedshouldenabletheengineertomakeamorerationalassessmentoftheriskofserviceabilityfailureinabraced excavation. The study points to the potential of the bootstrap method in coping with the problem of having to evaluate failure probability with uncertain sample statistics. DOI: 10.1061/(ASCE)GT.1943-5606.0000734. © 2013 American Society of Civil Engineers. CE Database subject headings: Excavation; Bracing; Serviceability; Probability distribution; Parameters; Uncertainty principles; Statistics. Author keywords: Probability distribution; Parameter uncertainty; Sample statistics; Bootstrapping; excavation; Ground settlement; Wall deflection.

Probability of serviceability failure in a braced excavation in a spatially random field: Fuzzy finite element approach

A simplified framework is proposed for evaluating the probability of “serviceability failure” in a braced excavation in a spatially random field. Here, the “serviceability failure” is said to occur when the excavation-induced wall or ground movement exceeds specified limiting values. Knowledge of this probability can aid in engineering decision-making to prevent damage to adjacent infrastructures. The proposed framework consists of five elements: (1) finite element method (FEM) for analyzing wall and ground responses in a braced excavation, (2) fuzzy set modeling of parameter uncertainty, (3) spatial averaging technique for handling spatial variability, (4) vertex method for processing fuzzy input through FEM model, and (5) interpretation of fuzzy output. The proposed framework is demonstrated through a well-documented case history. The results show the proposed framework is simple and effective for assessing the probability of serviceability failure in a braced excavation in a spatially random field. To focus on the proposed fuzzy FEM approach, the scope of this paper is limited to one-dimensional modeling of spatial variability with an assumed exponential autocorrelation function.