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Temporary anchorage devices (TADs) address challenges in traditional orthodontic anchorage like patient compliance and precision, showing significantly improved clinical outcomes, particularly for cases requiring maximum anchorage. A systematic electronic search was performed in five research databases, focusing on studies published between 2015 and 2023. The ROBINS-I tool from the Cochrane Bias Methods Group assessed the risk of bias. Data analysis included categorical and numerical variables, with categorical variables analyzed using Cohen's method in a random effects model to account for variability. Sensitivity and heterogeneity were evaluated using a 'leave-one-out' approach and the I 2 statistic, respectively. At the same time, publication bias was checked using Egger's test, with findings presented through Forest and Funnel plots. Numerical variables were subjected to weighted regression analysis. Examination of 15 studies involving 1981 patients and 3272 orthodontic mini-implants identified key factors affecting implant stability. Failure rates varied significantly, influenced by factors such as the characteristics and insertion site of the orthodontic mini-implants (OMIs), patient-specific variables, and operator experience. Notably, the insertion site and implant characteristics like size did not significantly affect failure rates, but there was a negative correlation between the magnitude of force applied and failure rates. The success of orthodontic mini-implants is broadly consistent across patient demographics and is not significantly impacted by gender or age, though failure rates were higher in males and when implants were placed in the maxilla. These findings suggest that higher applied forces might reduce failure rates. This review underlines mini-implant efficacy across varied patient demographics, emphasizing the importance of site selection, jaw location, and force application in enhancing success rates and guiding tailored treatment strategies. PROSPERO ID CRD42023411955. [ABSTRACT FROM AUTHOR]

Agreement on success following surgical treatment for periprosthetic joint infection (PJI) is important for comparing the efficacy of different surgical approaches with varying consequences and outcomes and setting patient expectations. We compared success rates following two-stage exchange arthroplasty for knee PJI using two expert-consensus definitions of success. Prospectively documented data for 57 knees treated by a single surgeon at an academic tertiary care center were retrospectively reviewed. Treatment outcomes were quantified using the Delphi Consensus Criteria and the Musculoskeletal Infection Society Outcome Reporting Tool (MSIS ORT). Success rates were 81% using the Delphi Consensus Criteria and 56% using the MSIS ORT (P =.008). The MSIS ORT success rates increased to 76% when aseptic revisions and deaths unrelated to PJI were not penalized as failures of treatment. Predicted probabilities of successful treatment in a hypothetical case scenario were lowest based on the MSIS ORT and similarly higher using Delphi Consensus Criteria and MSIS ORT modified for both women (53.0, 90.8, and 88.7%) and men (29.1, 89.1, and 89.3%). Study observations underscore the need for a uniformly accepted single definition of surgical treatment success. [ABSTRACT FROM AUTHOR]

Allograft prosthetic composite (APC) reconstruction is performed after resection of proximal humerus tumors or failure of arthroplasty implants. There is limited literature on the postoperative outcomes of this technique. We sought to assess implant survival, failure rates, and postoperative functional outcomes after APC reconstruction of the proximal humerus. A systematic review of the PubMed and Embase databases was conducted. The study was registered on PROSPERO (ID: 448,663). The Strengthening of the Reporting of Observational Studies in Epidemiology checklist was used for quality assessment. Implant failure was determined using the Henderson classification for biological reconstruction. Functional outcome was primarily assessed using the Musculoskeletal Tumor Society score at last follow-up. Twenty-five studies with a total of 488 patients were included. Mean follow-up in reporting studies ranged from 2.5 to 10 years. Five-year revision-free survival for implants ranged from 41% to 92%. Overall implant failure rate ranged from 9% to 54%, and reoperation rate ranged from 0% to 55%. Graft host nonunion (type 2) was the most common mode of failure, with rates ranging from 0% to 75%. The mean Musculoskeletal Tumor Society scores at last follow-up ranged from 57% to 90% across studies. A trend towards better functional outcomes was seen in patients having an APC with a reverse total shoulder arthroplasty (rTSA) compared with those with hemiarthroplasty. APCs show promise in proximal shoulder reconstruction, with heterogeneous functional outcomes that are noninferior to other reconstruction techniques. Graft host nonunion is a common mode of failure and remains a concern in this type of prosthesis. Future studies should compare rTSA-APCs and rTSA endoprostheses while controlling for potential confounders. [ABSTRACT FROM AUTHOR]

• Alveolar ridge miniscrews are an excellent choice of anchorage in an edentulous site. • Their survival rate was (62.0%) over a mean follow-up duration of 35.84 ± 19.47 months. • Clinical and demographical variables had minimal effects on their clinical efficacy. • Splinting adjacent miniscrews had a reported survival rate of 100%. An uncommon location for placing miniscrews, used to provide anchorage control in various tooth movements, is the alveolar ridge. This study aimed to provide an evaluation of the success rate of alveolar ridge miniscrews and examine variables that might impact their success. Charts for 295 patients who had miniscrews were screened. Twenty patients (5 male and 15 female: average age = 38.15 ± 15.10 years) with a total of 50 alveolar ridge miniscrews were analyzed. A customized data form was used to collect patients' and miniscrews' related variables. Kaplan–Meier estimator was used for the survival function, whereas Cox proportional hazards regression models were used to associate collected variables with alveolar ridge miniscrew survival. In total, 31 (62.0%) miniscrews were stable and 19 (38.0%) failed. The survival time for those that failed was 6.03 ± 7.08 months. The follow-up period for those that survived was 35.84 ± 19.47 months. Male gender versus female (hazard ratio [HR] 2.46; 95% confidence interval [CI] 1.35–4.48; P = 0.003), and if the miniscrew was a replacement versus non-replacement (HR 0.27; 95% CI 0.07–0.99; P = 0.048) influenced the survival. Additionally, miniscrews that were used for both indirect and direct or indirect anchorage alone plus those with evidence of splinting showed a 100% survival rate, which led to an HR 0 (P < 0.001). When the previously mentioned variables were modeled, none seemed to have a significant effect on failure except for splinting and type of anchorage (P < 0.001), because none of the splinted miniscrews failed. The failure rate of alveolar ridge miniscrews was (38.0%) over 6.03 ± 7.08 months. The survival rate was (62.0%) over 35.84 ± 19.47 months. The evidence of splinting and the type of anchorage had a significant effect on survival probability. [ABSTRACT FROM AUTHOR]

Dual mobility (DM) constructs for revision total hip arthroplasty (THA) have continued to grow in popularity to mitigate instability. This benefit comes at the cost of potential unique modes of failure, and there are theoretical concerns that combining femoral and acetabular components from different manufacturers could lead to increased failure rates. We aimed to investigate rates of reoperation between matched and unmatched DM implants used in revision THA. We retrospectively reviewed 217 revision THAs performed with DM constructs between July 2012 and September 2021 at a single institution. Dual mobility (DM) constructs were classified as "matched" if the acetabular and femoral components were manufactured by the same company. They were classified as "unmatched" if the acetabular and femoral components were manufactured by different companies. The primary outcome was reoperation for any reason. There were 136 matched DM constructs and 81 unmatched constructs. Average follow-up was 4.6 years (range, 2.0 to 9.6 years). There was no difference in reoperation rate between matched and unmatched groups (11.0 versus 13.6%, P =.576). The most common reasons for reoperation in both groups were instability and periprosthetic joint infection. There was 1 revision for intraprosthetic dislocation in the matched group. The use of unmatched DM components in revision THA was common and did not increase the risk of reoperation at an average of 4.6-year follow-up. This information can be helpful in operative planning, but further research on long-term survival will be necessary. [ABSTRACT FROM AUTHOR]

Safety instrumented systems(SIS) have been widely used in petroleum and chemical plants to detect and respond to dangerous events and prevent them from developing into accidents. The in-service time of SIS does not exceed its useful life is one of the crucial assumptions of IEC functional safety standards. The testing method recommended in the IEC standard is essentially a chi-square testing, where the testing effect is proportional to the sample size and, therefore, not suitable for testing the type of data distribution under small samples. In this paper, a rapid inference method of useful life (RIUL) is proposed to: i) determine whether the distribution type of failure data is exponential under small samples with the help of Anderson-Darling testing, and ii) use the Bayesian sequential testing method for estimating the useful life. The sequential posterior odds ratio testing is introduced to test the equipment failure rate one by one. The proposed RIUL approach is applied to the liquid-level protection circuit of the hot high-pressure separator. The engineering simulation results show that compared with IEC standard methods, the proposed method can be performed with fewer failure data, providing a theoretical basis for reasonable maintenance and replacement of equipment. [ABSTRACT FROM AUTHOR]

Peripheral intravenous catheterization (PIVC) is pivotal to pediatric medical care; however, it is a challenging technique for pediatricians, and the parameters affecting successful pediatric PIVC establishment have not been fully investigated. This prospective observational study collected data from pediatric patients aged less than 18 years who required PIVC. The participants were categorized into five groups for subgroup analysis: newborn, infant, toddler, pre-school, and student (children and adolescent). Data on demography, biochemistry, and PIVC executors were examined to elucidate the most powerful factors affecting the success of PIVC. A total of 935 peripheral venous cannulations conducted within 1 year were studied. Age-subgroup analysis showed the highest failure rate (FR) of PIVC in the infant group (18.4%). No significant difference in BMI standard deviation score was noted among the groups (p-value = 0.430). Compared with those for the success group, more attempts, longer completion time, and more medical staff were needed for the failure group (all p-values < 0.05). A high serum procalcitonin level was correlated with an increased FR (p-value = 0.016). In addition, the success rate was positively associated with the seniority of the operators, except for the 3-year experienced R3 group (93.5%) showing a higher success rate than the 4-year experienced CR group (84.2%). Difficulty in setting up PIVC was the greatest in infants and even greater than that in newborns. Even though seniority was a cardinal factor in successful PIVC, a high FR was still noted despite the lack of continuous and steady practice. [ABSTRACT FROM AUTHOR]

Over recent decades, splenic angioembolization (SAE) as an adjunct to non-operative management (NOM) has emerged as a prominent intervention for patients with blunt splenic injuries (BSI). SAE improves patient outcomes, salvages the spleen, and averts complications associated with splenectomy. This systematic review aimed to evaluate the failure rate and complications related to SAE in patients with BSI. A systematic literature search (PubMed, SCOPUS, and Cochrane Library) focused on studies detailing splenic angioembolization in blunt trauma cases. Articles that fulfilled the predetermined inclusion criteria were included. This review examined the indications, outcomes, failure rate, and complications of SAE. Among 599 identified articles, 33 met the inclusion criteria. These comprised 29 retrospective studies, three prospective studies, and one randomized control trial. The analysis encompassed 25,521 patients admitted with BSI and 3,835 patients who underwent SAE. The overall failure rate of SAE was 5.3 %. Major complications predominantly were rebleeding (4.8 %), infarction (4.6 %), and abscess formation (4 %). Minor complications were fever (18.4 %), pleural effusion (13.1 %), and coil migration (3.9 %). Other complications included splenic atrophy, splenic cyst, hematoma, and access site complications such as splenic/femoral dissection. Overall, post embolization mortality was 0.08 %. SAE is a valuable adjunct in managing BSI, with a low failure rate. However, this treatment modality is not without the risk of potentially serious complications. [ABSTRACT FROM AUTHOR]

This paper proposes a risk informed decision-making framework for siting Major Accident Hazard Installations in Sri Lanka. It is named the "Upper Bound FN curve" method. Generic failure rate data are utilized as country specific data are not available. FN Curves are derived for each process node of a Major Accident Hazard Installation using different failure rate data sets available in literature. The data sets giving the "worst case" FN Curve for each process node is identified. These FN Curves are called the Upper Bound FN Curves. Using these curves, a composite FN Curve is developed which is compared against the country specific risk acceptance criterion line. If the risk is not acceptable, further safety barriers are introduced. Safety distances are then determined using a scaling factor developed in this study called the relative risk reduction factor (RRRF). The RRRF is determined based on the comparative position of the composite FN curve with respect to the criterion line. The proposed methodology was applied in a case study of liquefied propane storage tank. Guidelines for application of the proposed framework, interpretation of the "Upper Bound FN Curve" method and estimation of safety distances are presented. [ABSTRACT FROM AUTHOR]

Evaluar el efecto de los problemas técnicos y de las características de las pacientes, en la detección gammagráfica del ganglio centinela (GC), y el éxito del mapeo en estadios precoces del cáncer endometrial (CE). Se incluyeron pacientes con estadio precoz de CE (IA-IB) sometidos a mapeo de GC empleando nanocoloides de 99mTc entre septiembre de 2011 y febrero del 2020. Fueron excluidos los casos con problemas técnicos, 92 pacientes se incluyeron en el análisis para valorar la rentabilidad diagnostica y la relación del mapeo linfático (pélvico unilateral o no detección del GC) con las características del paciente (edad, índice de masa corporal, enfermedad o cirugía pélvica previas) y de la enfermedad (histología, grado, invasión miometrial, infiltración del espacio linfovascular, tamaño tumoral y riesgo de infiltración linfática). La tasa de detección global fue del 79%. En 7 pacientes se detectaron metástasis ganglionares. La edad (p=0,01), profundidad de invasión miometrial ≥ 50% (p=0,04) y el alto riesgo de infiltración linfática (p=0,02) se asociaron de forma positiva con el fallo linfático. En el análisis multivariante, la edad se asoció significativamente con el fallo del mapeo [odds ratio=1,63; IC:95%: 1,06-2,50; p=0,027]. La edad, profundidad de invasión miometrial y el alto riesgo de infiltración linfática fueron los factores asociados con mayor fallo de mapeo. Una técnica de inyección individualizada, optimizando la metodología, podría minimizar los fallos de detección. To evaluate the effect of technical problems and patient characteristics on sentinel lymph node (SLN) scintigraphic detection and mapping success in early stages of endometrial cancer (EC). Patients with clinical early stage EC (IA-IB) underwent SLN mapping using technetium-99m-nanocolloid,between September 2011 and February 2020. were included. There were excluded cases with technical problems, 92 patients were included for the analysis of the diagnostic performance and the relation of mapping failure (pelvic unilateral or not detected SLN) with patient (age, body mass index, previous pelvic disease or surgery) and disease characteristics (histology, grade, myometrial invasion, lymphovascular space infiltration, tumor size, and lymphatic infiltration risk). The overall detection rate was 79%. Lymph node metastases were diagnosed in 7 patients. Age (p=0.01), depth of myometrial invasion ≥ 50% (p=0.04) and high risk of lymphatic infiltration (p=0.02) were positively associated with mapping failure. In multivariate analysis, age was significantly associated with mapping failure [odds ratio=1.63, 95%CI: 1.06-2.50; p=0.027]. Age, depth of myometrial invasion and high risk of lymphatic infiltration were the factors associated with higher mapping failure. An individualized injection technique, optimizing the methodology, could minimize the detection failures. [ABSTRACT FROM AUTHOR]

• A maintenance model based on the shot-noise process is studied. • The failure rate increments caused by shocks needn't be identically distributed. • Periodical PM policy is adopted for the system subject to shocks. • Expression of the long-run average cost rate is derived explicitly. • Existence and uniqueness of the optimal PM policy are proved theoretically. External shock process, known as the shot-noise process, will lead to the failure rate increasing of systems operating under random environment. In this paper, assuming that each shock may cause a random increment of the system failure rate, the optimal periodic preventive maintenance (PM) policy for the system is investigated. The system is preventively maintained at periodic time points n T , n = 1 , 2 , ... , N − 1 , and is preventively replaced at time point N T. The PM is not perfect, however, it can remove the accumulated failure rate increments caused by external shocks occurred during the last PM interval. When the system fails during the PM intervals, a minimal repair is performed to restore the function of the system. The expression of the average cost rate of the system is derived explicitly. The existence and uniqueness of the optimal bivariate PM policy (N , T) that minimizes the average cost rate are proved theoretically. Numerical examples are presented to illustrate the maintenance model and show the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

Benchmarking and comparative testing of three approaches for direct counting of stability failures are described. These approaches are based on the estimation of the failure rate from sample data using exponential distribution of time to failure, statistical frequency of failures and binomial distribution. All three approaches were included in the Explanatory Notes for the Second-Generation IMO Intact Stability Criteria. A brief description of the respective step-by-step procedures is included in the paper for convenience. The benchmarking is carried out using data synthesized from a Poisson process. A practical issue of decision making, based on direct counting, is discussed and the influence of the sample size is analyzed. • Benchmarking and comparative testing of three approaches for direct counting of stability failures are described. • The benchmarking is carried out using data synthesized from a Poisson distribution. • The three tested approaches were included in the draft Explanatory Notes for the Second-Generation IMO Intact Stability Criteria. • The rate estimators, their bias, variance, and the confidence intervals for failure rate are analyzed. • A practical issue of decision making, based on direct counting, is discussed and the influence of the sample size is analyzed. [ABSTRACT FROM AUTHOR]

System reliability and life-cycle cost are significantly influenced by preventive maintenance (PM). PM is commonly classified into two categories: time-based maintenance (TBM) and condition-based maintenance. Another PM approach referred to as inspection-based maintenance (IBM) incorporates condition-based activities within periodic inspections and tests. Determining the optimal maintenance rate for both TBM and IBM plans, and scheduling them effectively, poses a crucial challenge. Traditional methods assess equipment importance and condition within a reliability-centered maintenance framework. Mathematical models are commonly employed to devise robust plans, but accurate modeling based on practical conditions of the system equipment remains a key challenge. This two-part paper series introduces a novel model based on the Markov chain theory, that establishes the relationship between equipment status transition rates and the risk indices. The proposed model can be used alone or in combination with risk analysis outcomes to overcome data and budget limitations. To demonstrate its efficacy, the proposed method is implemented to optimize the PM rate of high-voltage equipment within a real-world sub-transmission substation, where the results can aid in cost estimation, equipment replacement decisions, and inventory management. • A failure rate estimation method for maintenance analysis of large-scale systems. • A probabilistic model to optimize dynamically the rate of inspections/routine tests. • Derived relations between the transition rates. • A new method for classification and analysis of failures and defects. [ABSTRACT FROM AUTHOR]

These two-part paper series aim to optimize the rates of inspection-based maintenance or routine-test on power system equipment. Part I introduced a novel probabilistic model using Markov chains for the inspection-based maintenance and derived the relationships between the transition rates. Part II demonstrates how the proposed method can effectively address budget and data availability constraints. It also presents the derived relationships between the optimal preventive maintenance rate and risk indices. The results presented in this paper are based on an industrial project conducted to optimize the preventive maintenance period of high-voltage equipment in Iran. Additionally, this companion paper provides practical insights, including implementation remarks, and a comprehensive dataset for failure and defect analysis, which proves useful for future research and applications. • A case study on a real sub-transmission substation for the proposed model. • Derived relations between the optimal preventive maintenance rate and risk indices. • Analysis of the simultaneity in the inspection of series components. • How to overcome data and budget limitations by the proposed sensitivity analysis. • Practically, how to use the available data to optimize the inspection rate. [ABSTRACT FROM AUTHOR]

Value of the lost load (VOLL) is a useful quantity in economical evaluations of power systems. The VOLL depends on multiple factors such as type of customer, regional economic conditions and demographics, time and duration of outage, and other specific traits of power interruption. The reviewed literatures show that there are still issues which could be considered in estimation of the VOLL, especially for industrial customers. One of the most interesting issues is inclusion of reliability of an industrial plant in estimation of the VOLL. This means that how reliability data of the plant components (failure rates, repair time, etc.) can be incorporated in the studies to provide a probabilistic model for the VOLL and its related quantities. This paper incorporates failure probability in the VOLL estimation of an industrial plant. For this purpose, firstly an estimate for failure rate of the plant components is obtained and secondly, this estimate is applied in failure probability function which is to be incorporated in the VOLL. Results provide a probabilistic model for the VOLL. [ABSTRACT FROM AUTHOR]

Early-life reliability is a key characteristic for complex technical products as it addresses the very first time-span of product use. Any unreliability in this phase jeopardizes both customer satisfaction, as well as warranty costs and finally the economic success. Review of several early-life warranty cases shows a mix of classical reliability issues, i.e., problems occurring during usage time, and quality related issues that often manifest themselves during initial inspections by product quality or even the customer, i.e., at usage time t = 0. Classical reliability growth models do not explicitly consider these two different sources of unreliability but require zero failures at time zero and provide time-dependent reliability estimates. We present a model which shares the concept of time-dependent reliability measures but considers in addition the initial quality issues. By taking advantage of well-known reliability growth models and basic statistical principles we were able to provide a flexible approach useful for practical application. [ABSTRACT FROM AUTHOR]

There is no consensus on the treatment of irreparable massive rotator cuff tears. The goal of this systematic review and meta-analysis was to (1) compare patient-reported outcome scores, (2) define failure and reoperation rates, and (3) quantify the magnitude of patient response across treatment strategies. The MEDLINE, Embase, CENTRAL (Cochrane Central Register of Controlled Trials), and Scopus databases were searched for studies including physical therapy and operative treatment of massive rotator cuff tears. The criteria of the Methodological Index for Non-randomized Studies were used to assess study quality. Primary outcome measures were patient-reported outcome scores as well as failure, complication, and reoperation rates. To quantify patient response to treatment, we compared changes in the Constant-Murley score and American Shoulder and Elbow Surgeons (ASES) score with previously reported minimal clinically important difference (MCID) thresholds. No level I or II studies that met the inclusion and exclusion criteria were found. Physical therapy was associated with a 30% failure rate among the included patients, and another 30% went on to undergo surgery. Partial repair was associated with a 45% retear rate and 10% reoperation rate. Only graft interposition was associated with a weighted average change that exceeded the MCID for both the Constant-Murley score and ASES score. Latissimus tendon transfer techniques using humeral bone tunnel fixation were associated with a 77% failure rate. Superior capsular reconstruction with fascia lata autograft was associated with a weighted average change that exceeded the MCID for the ASES score. Reverse arthroplasty was associated with a 10% prosthesis failure rate and 8% reoperation rate. There is a lack of high-quality comparative studies to guide treatment recommendations. Compared with surgery, physical therapy is associated with less improvement in perceived functional outcomes and a higher clinical failure rate. [ABSTRACT FROM AUTHOR]

Accurate reliability prediction for tidal turbines is challenging due to scarce reliability data. To achieve commercialization, it is widely acknowledged that reductions in maintenance costs are vital and robust component reliability assessments can help drive this. For established technologies, reliability prediction either involves a statistical assessment of historical failure data, or a physics of failure approach based on dedicated accelerated testing. However, for low/mid Technology Readiness Level tidal developers these common approaches are difficult. Thus, developers require a method of making reliability predictions for components in the absence of tidal turbine specific failure data and physical testing results. This paper presents a failure rate model for a tidal turbine pitch system using empirical Physics of Failure equations, with associated uncertainties. Critical component design parameters are determined and their effects on the failure rate investigated via a sensitivity analysis. The modelled failure rate is then compared with wind turbine failure data from a series of turbines. The tidal turbine failure rate is approximately 50% lower, however high reliability requirements mean this is unlikely to be acceptable. The developed model can assist turbine developers in estimating failure rates and determining reliability critical design parameters for the failure critical pitch system. • Reliability is a key driver of the cost of energy for tidal turbines. • Reliability prediction is challenging due to scarcity of relevant failure data. • The proposed model estimates failure rates using component design parameters. • The key design drivers for pitch system reliability are determined. • The simulated failure rate is found to be lower than comparable wind turbines. [ABSTRACT FROM AUTHOR]

Q-VAX® is a vaccine used to prevent Q fever. Administration of the vaccine is complicated by the need to ensure, using intradermal and serological tests, that individuals have no prior immunity. Previous studies suggest that the vaccine is highly efficacious and long-lasting in adults. However, there has been no systematic follow-up of vaccine efficacy and the longevity of immunity using population-level data. We aimed to investigate the vaccine failure rate and duration of immunity in previously vaccinated individuals. We formulated a retrospective cohort study design within a linked data. We used a Q fever vaccination registry linked to Q fever notifications and hospital admissions (1991–2016) in the state of Queensland, which has Australia's highest incidence of Q fever. Q-VAX® failure was defined as occurrence of Q fever > 14 days' after vaccination. The incidence of Q fever in vaccinated and unvaccinated individuals was 5.40 (95% CI: 3.65, 7.72) and 89.50 (95% CI: 70.50, 112.00]) per 100,000 person-years of follow-up, respectively. The hazard ratio (HR) for Q fever was 0.07 (95% CI: 0.04, 0.10) in non-immune vaccinated compared with immune unvaccinated individuals. The overall vaccine effectiveness was found to be 94.37% suggesting that Q-VAX® is highly effective at preventing Q fever. However, the greater incidence observed in unvaccinated individuals considered immune during the pre-vaccination screening may suggest that pre-vaccination screening is sub-optimal among this study population. [ABSTRACT FROM AUTHOR]

The purpose of this study was to review the current literature on rehabilitation protocols following arthroscopic meniscus repair. A systematic literature review was performed of Medline, Scopus, and Web of Science databases to identify relevant articles from January 1990 to April 2019. Search terms were (meniscus OR meniscal repair) AND (repaired OR repair) AND (rehabilitation OR physiotherapy OR physical therapy). Each study was independently scored for methodological research quality level using the Modified Coleman Methodology Score (MCMS). The following variables were extracted from each study: publication year, study type, evidence level, subject demographics, injury mechanism, meniscus tear type, surgical procedure, rehabilitation program [immobilization, weight bearing, ROM progression, therapeutic exercises, length of follow-up, patient-reported outcome measurements, return to sport timing/criteria and failure rate/criteria. Eighteen studies met the inclusion criteria. The overall MCMS was moderate 59.5 ± 11.7 (range = 42–90). The average MCMS score for postoperative rehabilitation was 4.7 ± 1.18. Only 1 (5.6%) study was a prospective randomized controlled trial and 14 studies (78%) had retrospective designs. Fourteen (78%) studies suggested that return to sports should occur between 3 and 6 months post-surgery. Early range of motion and immediate weight-bearing had no influence over patient-reported outcomes or failure rates for vertical meniscus tear repairs. Low MCMS scores, primarily retrospective study designs and poorly described postoperative rehabilitation protocols made it difficult to design an evidence-based therapeutic rehabilitation program for patients following arthroscopic repair of an isolated meniscus tear. An arthroscopic isolated meniscal tear repair rehabilitation protocol is being attempted to present based on a synopsis of existing evidence. • Accelerated post-operative rehabilitation protocols do not generate higher failure rates in vertical tear repairs. • More precise decision-making measurement criteria are needed for return to sports. • Further prospective studies are needed to delineate rehabilitation protocol different meniscus tear types. [ABSTRACT FROM AUTHOR]

This paper describes the experimental approach to be performed to examine the reliability indicator of certain electrical devices manufactured by companies in the Russian Federation. The tests will be conducted according to technical specifications and test procedures which were prepared for these devices. In addition, a comparison referring to the reliability parameters between results and manufactured specifications will be provided or conducted. [ABSTRACT FROM AUTHOR]

• Two PV farms with an output of 20 MW were designed and their performances were studied. • Based on Markov processes and Z transformation a model to calculate the reliability indices of PV system was developed. • The obtained reliability indices are 83% and 88% for the studied solar farms. The quest for alternative energy sources, replacing the environmentally impacting fossil fuels, has resulted in the growing need to develop various new strategies in the field of renewable energies. A possible energy source is clean solar energy. The most common technology used is a silicon semiconductor device, which generates electrical output while interacting with light, known as Photo-Voltaic (PV) System. The reliability of PV modules and systems is critical to the commercial success of Photovoltaic systems. The technology combines multiple components, each of which could cause a system failure or energy losses. The reliability characterization measurements of a PV power system are complicated and only a few studies succeeded to design and simulate an efficient PV system. In the current study, two relatively large-scale solar farms were designed with an output of 20 MW. A comparison of the solar farms' performances was conducted, with an emphasis on the reliability indices of the systems. The obtained reliability indices are 83% and 88% for the studied solar farms. [ABSTRACT FROM AUTHOR]

In turbulent environments, one of the fundamental problems is the high risk of failure in new innovation projects that affects organizational behaviour and performance of firms and also nations. The study here clarifies the theoretical structure of project-level failure proposing a new definition, based on systems approach (Innovation failure is when organization does not achieve the main goal of project because of a set of errors), and a taxonomy of three general types of error in innovation failures: errors in planning and/or design, in project execution/implementation and in marketization. A case study research clarifies the proposed framework of innovation failures with examples from pharmaceutical sector, aerospace and aircraft industries, and information & communication technology sector. Results suggest that the failure in innovation projects is due to proposed errors associated mainly with bounded rationality of organizations in dealing with goal difficulty, environmental complexity and uncertainty. Different strategies of problem solving to reduce errors and risks leading to innovation failures and improve technological development are proposed, such as learning processes, adaptation perspective, game theory approach, stage-gate method, etc. The proposed systemic concept of innovation failure and related taxonomy of general typologies of error can guide R&D managers, designers, analysts, and policymakers etc. to know main determinants of failure in innovation projects and how appropriate strategies can improve organizational performance and R&D processes of firms for competitive advantage in markets and society. [Display omitted] • ∑ i = 1 n f a u l t i ⇒ error j, ∑ j = 1 m e r r o r j ⇒ Failure in innovation projects. • Main errors in innovation failure are in planning and design, execution and market orientation. • Innovation failure is associated with goal difficulty, environmental complexity and uncertainty. • Learning and adaptation, stage-gate and bathtub strategies reduce innovation failure. • Error in market orientation can induce failure with Concorde effect. [ABSTRACT FROM AUTHOR]

• Comparison of crystalline-Si PV systems from 2-different PV manufacturers. • Identification of degradation mechanisms associated with EVA. • Mechanisms of chemical degradation are presented associated with loss of performance. • Comparisons using EL and UV to highlight performance differences. This paper reports on a unique evaluation-opportunity for comparing modules from two-different manufacturers that were deployed for a long-period (~15 years) under similar circumstances: (a) for the same distributed, rural-power applications, (b) operating under the same climate-conditions and geographical area, (c) with devices manufactured and installed at the same time. But these modules had very different resulting observed changes in their operational and physical characteristics over their long field-exposures. The PV modules were dispersed in a tropical climate-zone (northern-region of Minas Gerais, Brazil). Visual inspections of the two-module sets concluded that one module source (SET A) had almost no encapsulant discoloration and few indications of delamination and corrosion. In contrast, the other module source (SET B) had significant yellowing/browning, widespread-areas of delamination, and fairly extensive interconnect-corrosion. The corresponding measured changes in the electrical characteristics were: SET A having average annual loss in power of 0.4–0.5%, and SET B with 2.3–3.7%/year over their installation times. Encapsulant discoloration and delamination provided the first clues to the measured differences in module performance and are attributed to the existing climate conditions of high-ultraviolet (UV) radiation exposures and high-ambient temperatures. The bases for the performance differences of these two module sets were examined using complementary electrical, physical and chemical characterization of the module materials. The primary goal of this paper is to identify the root causes for the degradation differences (one set meeting specifications, the other not), based upon the critical module materials properties/processing and climatic exposures. [ABSTRACT FROM AUTHOR]

• Provides a template for high level classification of functions and failures. • Uses BBNs to capture uncertainty in the assessed compliance scenario. • Uses BBNs to extend compliance scenarios to multiple assessments. • Removes the requirement for assessing single credible (often worst-case) scenarios. • Applies BBNs within an aviation SSR "Part 1309" system safety context. • Provides a case study application of unmanned aircraft systems. There can be significant uncertainty as to the safety of novel or complex aviation systems, such as Remotely Piloted Aircraft Systems (RPAS). Current aviation safety assessment and compliance processes do not adequately account for uncertainty. The aim of this research is to support more objective, transparent, systematic and consistent regulatory outcomes in relation to the safety assessment of such systems. The objective of this work is to provide a systematic means of accounting for the various uncertainties inherent to any System Safety Assessment (SSA) process. The paper first defines the system safety compliance process and its modification to account for uncertainty. The SSA process, its various outputs, and associated uncertainties are defined and then applied to a generic RPAS. A Bayesian Belief Network (BBN) is adopted that facilitates a more comprehensive treatment of the uncertainty in each of the outputs of a typical SSA process. A case study of a generic RPAS is used to illustrate the features of the new approach. The adoption of the Proposed SSA approach would allow for the high uncertainty associated with the safety assessment of novel or complex aviation systems, such as RPAS, to be taken into consideration. Such an approach would enable the risk-based regulation of the sector. [ABSTRACT FROM AUTHOR]

Highlights • The paper is focused on a critical review of methods for the evaluation of failure rate distribution parameters. • Two test cases related to avionics components under accelerated test are presented. • The probability plot of all the distributions and a rank of the best-fit distributions are discussed in detailed. Abstract The paper provides an overview of the principal failure rate distributions and it is focused on the comparison between exponential and Weibull distributions: this study illustrates the advantages and disadvantages of the constant failure rate of the exponential distribution and the Weibull time-dependent behavior. The second part of the paper deals with the parameter estimation methods that used to determine the best-fitting distribution for a set of data collected during testing or field operations. The methods considered in that case are probability plotting, Least Square Estimation and Maximum Likelihood Estimation. Finally, two different types of field data such as failure times achieved with testing of electronic board for avionics components are analyzed by software to find which distribution fits better the data. [ABSTRACT FROM AUTHOR]

Abstract Determination of gas pipeline failure rates is essential for quantitative risk assessment and integrity management of gas pipelines. To this end, the functional relationship between failure rate and failure probability is established by reliability theory, considering that the two terms are often confused in the literature. Then, existing methodologies for the estimation of failure rates are divided into three categories, namely methods based on historical failure data statistics, methods based on expert knowledge and experience, and methods based on structural reliability analysis. Finally, characteristics and applicability of the three methods are compared. We find three essential aspects to consider in determination of the choice of method in practical engineering: (1) operation and management level of gas suppliers, (2) features or merits of detection technologies of pipelines, and (3) integrity of pipeline failure databases. Considering that external interference as a cause of failure belongs to a type of extreme failure load, it would be appropriate to adopt methods based on historical failure statistics to determine failure rates. On the contrary, when historical data are relatively scarce or the pipeline detection technology is advanced, it is advisable to use methods based on structural reliability analysis to obtain the failure rates. In this study, the calculation model and procedures for the method based on historical failure data statistics are established. Furthermore, the so-called bathtub curve of pipeline failure rates is obtained by methods based on structural reliability analysis. Highlights • The relationship between failure rate and failure probability is described. • Applicability of methods for calculating pipeline failure rate is analyzed. • The calculation model of failure rate due to external interference is established. [ABSTRACT FROM AUTHOR]

Background We performed arthroscopic rotator cuff repair (ARCR) combined with miniopen supraspinatus and infraspinatus muscle advancement for massive rotator cuff tears (RCTs) to decrease tension at the repair site with the goal of reduction of the failure rate. We evaluated the clinical outcomes and failure rate after this procedure. Methods This study included 47 patients diagnosed with chronic massive RCTs between October 2010 and March 2015. Of these patients, 21 underwent transosseous equivalent (TOE) ARCR only (control group), and 26 underwent TOE ARCR with muscle advancement (study group). We evaluated shoulder clinical outcomes at preoperative and postoperative assessments and also measured muscle strength and the acromiohumeral interval (AHI) at the same time in both groups. Failure rates were calculated in both groups by evaluating the cuff integrity with postoperative magnetic resonance imaging. Results Although there was statistically significant improvement for the mean clinical scores in the both groups, there were no significant differences between the 2 groups. The postoperative abduction muscle strength and AHI were significantly higher in the study group (46.3 ± 20.6 N and 9.4 ± 2.9 mm; P =.04) than in the control group (34.6 ± 20.0 N and 7.7 ± 3.0 mm; P =.04). The failure rates were significantly lower in the study group than in the control group (23.1% and 52.4%; P =.03). Conclusion The TOE ARCR with muscle advancement can achieve significantly better abduction muscle strength, wider AHI, and lower failure rates for massive RCTs than the normal TOE ARCR. [ABSTRACT FROM AUTHOR]

Abstract Human activities, including design, construction, operation, management and maintenance are all a predominant part of the daily tasks in offshore operations. It is not surprising to observe major failures are related to human error, since humans are susceptible to making mistakes. Due to the high level of uncertainty in human activities, predicting all causes of human errors is not an easy process. This may lead to inaccurate results which may affect the overall safety and reliability of marine operations. Evaluation of human endurance during activity on board is a key factor in minimizing risk of human failure. This study aims to examine uncertainties over the time of the marine operation to estimate accurate human reliability assessment. A framework is developed to model the uncertainty of human performance factors by considering a hydrodynamic analysis of the structure along with a subjective analysis of human activities under different weather conditions. Subsequently, a model based on Dynamic Bayesian approach is developed to evaluate the time duration effect on human performance throughout the operation. The developed methodology has been applied to a case study of an offshore vessel storing extracted oil. The framework demonstrates that probability of human failure increases towards the end of its operational days, however the high variation in human reliability is greatly dependent on weather conditions. The present study is able to improve the safety of human life in marine operations by predicting the reliability of performances as a function of time during a specific operation. Highlights • Proposing a framework to evaluate human fatigue over the time in a marine operation. • Developing a Dynamic Bayesian Network for reliability assessment and predicting human endurance. • Considering the storm condition and hydrodynamic response of the structure for predicting human fatigue. • Model the uncertainty of human performance factors under the conditions of different weather conditions. [ABSTRACT FROM AUTHOR]

Highlights • Failure rate and probability are proved to be increasing with time. • The generalized linear model (GLM) is built for Poisson Binomial distribution. • Time-dependent failure rate and probability of nuclear component are analyzed. • The GLM is proved to be reasonable by the qualitative graph and Bayesian methods. Abstract Reliability data of nuclear component are the input parameter and important to the nuclear power plant probabilistic safety assessment. If the failure is weariness in origin, the failure rate and probability will be not constant and have a time trend. Failure rate and probability have been proved to be increasing with time by reliability mathematics. The generalized linear model is built for Poisson and Binomial distribution and applied to study the time-dependent failure rate and probability of nuclear component. The model is proved to be reasonable by the qualitative graph and Bayesian chi-square statistic methods, which can predict the real time trend of nuclear component failure rate and probability correctly. Only analyzing the time dependent failure rate and probability of nuclear component, we will build more accurate general reliability data to analyze the uncertainty of system reliability. [ABSTRACT FROM AUTHOR]

Background The ulnar collateral ligament (UCL) of the elbow is commonly injured in overhead athletes, especially baseball pitchers. UCL reconstruction has shown good outcomes regarding return to play, but revision rates are on the rise. This review was conducted to determine the effect of elbow flexion angle during graft fixation on outcomes and complications after UCL reconstruction. Methods MEDLINE, Embase, and PubMed were searched from database inception to November 16, 2017. Patient demographics, surgical technique, graft selection, outcomes, and complications were extracted from the included studies. The quality of each study was assessed in duplicate with the Methodological Index for Non-Randomized Studies criteria. Descriptive statistics are presented. Results Six studies, with a total of 1168 patients, were included, and all were case series. Excellent Conway scores were present in 83.8% of patients for the 0° to 30° group and in 91.1% of patients for the 45° to 70° group, with no significant differences in return to play between the groups. The rate of revision UCL reconstruction was significantly higher with graft fixation at 0° to 30° (1.4%) compared with fixation at 45° to 70° (0%; P <.01). Conclusions Elbow flexion angle during graft fixation may not influence return to the same or higher level of competition but appears to influence the need for a revision after UCL reconstruction. However, the available current evidence possesses a high degree of fragility, and further studies are needed with objective measurements to determine the optimal elbow flexion angle for graft fixation. [ABSTRACT FROM AUTHOR]

Highlights • Reliability, Availability, Maintainability and Inspectability assessment for nuclear fusion plant requires Failure Rate data. • Failure Rates for ITER Divertor Inner Vertical Target component was estimated exploiting information conveyed by qualification tests. • A Bayesian Step-Stress Accelerated Life Testing framework was adopted to infer from the likelihood function depending on the observed data. • An Arrhenius-exponential model for stress levels was included in the considered Exponential and Weibull failure distributions parameters. • The Probability of failure for considered component was derived for a simulated pattern of heat load scenario. Abstract Reliability and availability performance assessment are useful tools in the design and delivery of fusion components to check whether expected system behaviour is likely to be observed. These analyses rely on failure rates input data, which must be estimated for components lacking operational experience. The proposed analysis is meant to gain insight on new components Failure Rates exploiting the information conveyed by qualification tests. In particular, a model for the failure rate (Exponential and Weibull model considered) and an Arrhenius-exponential model for failure rate dependency on the stress level are assumed. A parametric expression is thus derived for considered component failure rate. A set of high flux tests data part of ITER Divertor Inner Vertical Target components qualification programme is then statistically analysed in terms of censored data set and a survival likelihood function accordingly derived. Posterior distributions for failure model unknown parameters are finally inferred to provide a first approximation failure rate estimation. Despite the problematic assumptions that the usage of such preliminary and not-tailored-on-purpose data requires, the proposed method quantitatively supports RAMI analysts in the estimation of unknown failure rates taking advantage of currently available information. [ABSTRACT FROM AUTHOR]

Highlights • Safety studies for the European Demonstration Fusion Power Plant (DEMO). • Failure Mode and Effect Analysis (FFMEA) and accident identification. • Plasma events and disruptions. • Blanket concepts of the European DEMO reactor. Abstract Plasma disruptions represent the highest hazard for the integrity of plasma facing components in tokamak reactors. Several studies are performed in order to minimize their severity and occurrence or to mitigate their effects in case they happen despite the prevention carried out. In a power plant as DEMO, the disruptions should have low occurrence probability, relying on assumption that proper well qualified plasma scenarios and operative procedures will be identified and followed after ITER and other fusion facilities experimental campaigns. Anyway, the probability of technical failures of components leading to disruptions cannot be assumed low a priori. A specific study has been performed in order to have a first overview on this issue. The applied methodology benefits from a large set of safety and reliability/availability analyses performed in the past for ITER and DEMO. Possible failure modes of the components of DEMO systems are investigated. The main objective has been to highlight the overall failure events that happening during the plasma operations could lead to plasma disruptions or requests of controlled plasma shutdown. Finally, a first estimation of the probability of occurrence of such failure events has been provided on the base of: component failure rates available in literature, estimation of number of similar components in the plant and yearly time of plasma pulse operations. [ABSTRACT FROM AUTHOR]

• Optimal maintenance in dynamic populations of statistically identical items is discussed. • Systems that generate an output/gain/profit that has a cost-wise interpretation are considered. • Preventive maintenance for dynamic populations of items is studied. • Illustrative examples which confirm the theoretical findings are provided. This is the first study in the reliability literature that discusses optimal maintenance in dynamic populations of statistically identical items. Items that generate an output/gain with a value interpretation, e.g., the performed amount of work, the manufactured product, etc., are considered. The expectation of the overall gain on a cycle of performance defines the corresponding objective function for the preventive maintenance (PM) optimization for a single item, which is also used to develop theory for dynamic populations of items. It is shown that the optimal PM time for dynamic populations of items is larger than that for a single item. Generalizations to the cases when an item is characterized by the major and minor failures and when the output rate is a function of time are considered. It is shown how the framework developed here is relevant to an industrial setting using an example of a fleet of wind turbines. Some numerical results illustrate our findings. [ABSTRACT FROM AUTHOR]

• Developed a framework to quantify the uncertainties of deep learning-based failure rate prediction of water distribution networks. • Introduced a probability-based LSTM model that allows to simultaneously determine the mean value and standard deviations of model predictions. • Validated the framework with data from a large in-service water supply network. • Identified the influence of different sources of uncertainties on the reliability of ML model prediction. • Recommended methods to reduce the uncertainties associated with the LSTM model prediction. Predicting the time-dependent pipe failure rate of the water distribution networks (WDNs) is important for planning its renewal budget but also challenging due to the complex factors involved. The recent development of machine learning techniques provides a novel approach for accurate failure rate prediction based on historical data. However, the inherited randomness and uncertainty of water pipe failures and machine learning algorithms are often ignored in the training and prediction process. This article develops an uncertainty quantification framework for deep learning-based WDN system-wide failure rate prediction. The framework integrates a probabilistic long short-term memory (LSTM) model with a Monte Carlo method. The historical climate data and WDN pipe maintenance data over the past 35 years for Cuyahoga County, USA, are used to illustrate this deep-learning model-based uncertainty quantification framework in this study. A statistical time series regression model, ARIMAX, is used as a comparison benchmark. The results show that the LSTM model outperforms the ARIMAX model in prediction accuracy in most years by considering the uncertainties. Besides, the uncertainty range of the LSTM model prediction is 50% of that of the ARIMAX model. The results also identified the major contributing factors to the uncertainties of LSTM machine learning model prediction. The proposed uncertainty framework features excellent extensibility and can be adapted to quantify uncertainties with other types of machine learning models. [ABSTRACT FROM AUTHOR]

Security and stability control device plays a significant role in ensuring the reliable operation of power system. However, fault-operation, fail-operation, under-control and over-control could be caused by the failure of stability control devices and system. Taking SCS-500E, one kind of security and stability control device, the failure of hardware and software are discussed in this paper. According to device structure and failure data, the failure model of the device is established. The advantages of the Monte Carlo method are analyzed, and the failure probability of the device is calculated by this method. It is proved that the results worked by the method proposed in the paper are matched with the actual condition. [ABSTRACT FROM AUTHOR]

Maximizing the return on investment of a photovoltaic array requires a power electronics converter with the longest possible operational life. This paper is aimed at presenting a heatsink optimization approach to enhance the survival probability of a high-efficiency 1 kW DC/DC converter, specifically designed for PV applications. A main feature of the enhancement is that it takes into account the meteorological characteristics of the intended installation site: a coastal area with high humidity and cloudiness throughout the year. As a first step, the converter reliability is estimated according to the FIDES procedure, yielding a mean time between failures MTBF = 98.15 FIT. The numerical results pinpoint the diodes as the most failure-prone components, and temperature as the dominant stressor, clearly suggesting that the performance can be improved by resorting to better heatsinks. As a second step, a heatsink optimization problem is established, involving three objective functions: minimization of heatsink thermal resistance and weight, and maximization of the cooling system performance index, The problem is solved using a genetic algorithm, which yields MTBF = 74.09 FIT. The approach takes advantage of the computer tools currently available: mathematical toolboxes to implement the optimization algorithm, user-friendly reliability prediction software, and software packages capable of simulating the thermal behavior of heatsinks with good accuracy. [ABSTRACT FROM AUTHOR]

The existing standard reliability models for power devices are not satisfactory and they fall short of predicting failure rates or wear-out lifetime of semiconductor products. This is mainly attributed to two reasons; the lack of a unified approach for predicting device failure rates and the fact that all commercial reliability evaluation methods relay on the acceleration of one dominant failure mechanism. Recently, device reliability research programs are aimed to develop new theoretical models and experimental methods that would result a better assessment of the device lifetime as well as point out on the dominating failure mechanism for particular operating conditions. A new model, named Multi failure mechanism, Overstress Life test (MOL) has been introduced and posed a better understanding of the dominating failure mechanisms under various stressed conditions in advanced FPGA devices (for 45 and 28 nm technologies). In this work we present, for the first time, the implementation of the MOL model to investigate the reliability of silicon power MOSFET and GaN power FET devices. Both, LTSpice simulation and experimental data are presented for a test circuit of a ring oscillator, based on CMOS-FET, NMOS-FET, PMOS-FET and N-channel e-GaN FET. The monitored data was acquired in-situ in form of the ring frequency or Vds values that enabled to assess the lifetime and determine the dominating mechanism during accelerated wearout by temperature, applied bias voltage, thermal cycling, gamma and electron irradiation. Moreover, in the case of GaN devices, RDS-On monitoring circuit has also been operated during thermal cycling of the tested component and the acceleration factor was derived for various operational parameters. [ABSTRACT FROM AUTHOR]

The aim of PMU placement in power system is to provide network observability. Usually, the PMU placement is done assuming simple bus arrangement for all the network buses. Therefore, it does not guarantee the observability of complex buses under operational arrangements in which the lines at complex buses are not connected to each other at an individual busbar. In this paper, a new formulation for PMU placement is developed based on ILP that considers the necessity of the network observability under all possible arrangements of lines connections at complex buses. Moreover, in order to prevent the installation of PMU for observability under arrangements that are possible but are not actually probable, a probabilistic PMU placement is presented that considers only the probable configurations, each weighted by its probability. In this case, the lines outage and PMUs failure probability are also taken into account. The simulation results indicate the performance of the presented method to solve PMU placement problem in the presence of complex buses and show that more number of PMUs are required in a network with complex buses. [ABSTRACT FROM AUTHOR]

Station Black Out (SBO) is an accident situation that refers to the total loss of offsite power, along with the unavailability of onsite power, which results from the failure of all Diesel Generators (DG). Probabilistic Safety Assessment (PSA) spans a number of methods that include modeling of event-trees and simulation of accidents scenarios, aimed to quantify risk and ensure safety in nuclear power plants. PSA also deals with prediction of future accidents and calculation of failure probabilities that has been done in this study. A SBO accident was simulated using a Generic Pressurized Water Reactor (GPWR) simulator from KEYMASTER™. The accident scenario consists of two stages; the first stage belongs to normal SBO, in second stage SBO accident with additional failure of Pilot Operated Relief Valve (PORV) opens and it stuck open has been considered for the pressurizer. A comparison of the two stages was made by plotting variables on the same graph. The research has been carried out to analyze the hot and cold leg temperatures, Steam Generator (SG) pressure, SG Narrow Range (NR) level, SG water-level-percentage (PCT), Pressurizer pressure, Fuel Temperature, and containment pressure. Simulation results suggest that failure in closing PORV has negligible impact on hot and cold leg temperatures, results in an overall less pressure in SGs, but higher pressure in the pressurizer. Additionally, containment pressure did not exceed the maximum approved pressure of 8.7 kg/cm 2 , but was approaching the Advanced Pressurized Water Reactor’s (APR-1400) design pressure of 4.218 kg/cm 2 . Finally, nuclear fuel temperature exceeded Probabilistic Risk Assessment (PRA) limit of 726.7 °C for both scenarios. The research results will provide help in future for better understanding of accidents in APR-1400 reactors. [ABSTRACT FROM AUTHOR]

Reliability is a key parameter in Ethernet ring mesh networks. Therefore, an accurate analysis of reliability in Ethernet ring mesh including single or multiple rings is a main requirement. Since the calculation of reliability in such networks is an NP-hard problem, nearly most of the previous methods in this regard, were based on approximation. In this article, a new method namely, Remove and Contraction (R&C) is presented which is applicable to Ethernet ring mesh networks for precise calculation of reliability. In addition, the proposed method is a general method, which can be used for reliability analysis in other network systems as well. The analyses show the superiority of the R&C method to previous methods in terms of accuracy. [ABSTRACT FROM AUTHOR]

• Defining a comprehensive objective function using an extended mixed-integer linear formulation for optimal planning of long-term maintenance in distribution networks. • Considering the uncertainties of load, amount of undistributed energy, and energy sales price with the IGDT method in the objective function. • The use of practical indexes of reliability, including ENS, AENS, SAIFI, and SAIDI as the main indexes of the problem. • The proposed method has been implemented on the real network with 10 feeders in Markazi province of Iran. • Applying Meta-heuristic methods, including GA, to calculate the equations related to shape and scale coefficients in the Weibull distribution function. Considering the high number of customers, the extent and volume of interruptions, distribution networks are one of the most challenging parts of power systems; which need a well-organized and continuous planning for maintenance. Risk-based maintenance is the most recent approach used to plan the maintenance of networks. In this paper, for long-term planning of maintenance of overhead medium voltage distribution networks, an Extended Mixed-Integer Linear Formulation considering the uncertainties in the network has been proposed taking into account various constraints such as annual budget, energy not supplied as a result of preventive and corrective maintenance as well as the average energy not supplied has not been proposed, which is one of the main innovations of this study in comparison with other published researches. In this paper, four different modes including a deterministic mode and three non-deterministic modes in the network have been considered. To achieve accurate and practical results in real conditions, the proposed method has been implemented on a real network with 10 feeders in Markazi province of Iran. The results showed that the proposed program will optimize the annual costs of network maintenance, reduce interruptions and increase network reliability by considering various constraints. [ABSTRACT FROM AUTHOR]

With a few hundred spacecraft launched to date with electric propulsion (EP), it is possible to conduct an epidemiological study of EP's on orbit reliability. The first objective of the present work was to undertake such a study and analyze EP's track record of on orbit anomalies and failures by different covariates. The second objective was to provide a comparative analysis of EP's failure rates with those of chemical propulsion. Satellite operators, manufacturers, and insurers will make reliability- and risk-informed decisions regarding the adoption and promotion of EP on board spacecraft. This work provides evidence-based support for such decisions. After a thorough data collection, 162 EP-equipped satellites launched between January 1997 and December 2015 were included in our dataset for analysis. Several statistical analyses were conducted, at the aggregate level and then with the data stratified by severity of the anomaly, by orbit type, and by EP technology. Mean Time To Anomaly (MTTA) and the distribution of the time to (minor/major) anomaly were investigated, as well as anomaly rates. The important findings in this work include the following: (1) Post-2005, EP's reliability has outperformed that of chemical propulsion; (2) Hall thrusters have robustly outperformed chemical propulsion, and they maintain a small but shrinking reliability advantage over gridded ion engines. Other results were also provided, for example the differentials in MTTA of minor and major anomalies for gridded ion engines and Hall thrusters. It was shown that: (3) Hall thrusters exhibit minor anomalies very early on orbit, which might be indicative of infant anomalies, and thus would benefit from better ground testing and acceptance procedures; (4) Strong evidence exists that EP anomalies (onset and likelihood) and orbit type are dependent, a dependence likely mediated by either the space environment or differences in thrusters duty cycles; (5) Gridded ion thrusters exhibit both infant and wear-out failures, and thus would benefit from a reliability growth program that addresses both these types of problems. [ABSTRACT FROM AUTHOR]

In this work, we have demonstrated that many elements are needed on top of conventional foundry reliability knowledge to enable robust automotive products in compliance with all restrictive norms. For intrinsic reliability, both reliability models (a design compatible WLR description), and dynamic aging compensation schemes are required. For extrinsic failures, screening procedures require well documented usage and are shown in use for volume production to bring the failure rate level down below 1 ppm automotive target. Altogether, the global approach developed in STMicroelectronics enable robust automotive products based on controlled and validated procedures. [ABSTRACT FROM AUTHOR]

Background With the introduction of the deltoid tuberosity index (DTI), a simple radiographic tool has become available to measure bone mineral density of the proximal humerus. The aim of this study was to assess the influence of local bone mineral density on the early failure rate after angular stable open reduction–internal fixation of proximal humeral fractures (PHFs). Methods We retrospectively followed up all patients treated with angular stable implants for PHFs from 2007 to 2014. The fractures were classified according to Neer, and the DTI, metaphyseal head extension (MHE), medial hinge displacement, and quality of reduction were assessed. Failures were defined as head screw cutouts. Results The study included 146 patients (mean age, 66 years; range, 20-94 years). The mean follow-up period was 11 months (range, 3-94 months). Of the fractures, 91% were classified as 2- or 3-part fractures and 9% as 4-part fractures. The mean DTI was 1.44 (range, 1.19-2.11), and the mean MHE was 12 mm (range, 0-48 mm). The reduction result was at least acceptable in 80% of fractures. Screw cutouts were found in 23%. The DTI and MHE were the most significant preoperative predictors for the reduction result. The DTI ( P  = .036) and age ( P  = .02) were independent preoperative factors, and a good reduction ( P  = .001) was the only intraoperative factor influencing cutout. Discussion This study proves that good bone quality and a long MHE are helpful for the reduction. Furthermore, good bone quality, a younger age, and a good reduction prevent later cutout. We conclude that local bone quality is a relevant factor in the treatment plan for PHFs. [ABSTRACT FROM AUTHOR]

An extension of a system by redundancy is a method of system modification which can be used for failure detection, failure masking or recovery after a failure. Dependability system features (availability) and safety system features (safety integrity) can be improved in a desired manner by an application of redundancy. The resulting influence of redundancy on the system depends on used forms of redundancy and its application methods. The paper deals with a calculation of a failed state probability of the system with standby redundancy and it points out the importance of choosing of a suitable method for an analysis of a monitored system feature. [ABSTRACT FROM AUTHOR]

With growing environmental concerns over the climate change risks associated with power generation using fossil fuels, solar power generation has emerged as one of the most rapidly growing renewable sources of electricity in the world. In recent technological advancements for improving the performance of PV system, efficiency improvement of solar PV cell and power converter stage has become a critical area of interest for researchers. Sensitivity and reliability studies of a system are important tools to evaluate the performance of the system. In this paper, sensitivity and reliability models of a grid-connected PV system are developed. Analytical relations of first order sensitivity are developed for PV cell and DC-DC converter. Further, reliability models are developed for individual components and for different configurations of PV system using Pareto analysis and logic gate representations. The main reference for electronic component reliability evaluation is MIL-HDBK-217 military handbook and MTBF calculator software by ALD. The developed models can be applied to any PV system to have a better insight. [ABSTRACT FROM AUTHOR]

The IEC 61508 and IEC 61511 functional safety standards encourage the use of field feedback to estimate the failure rates of safety-related systems, which is preferred than generic data. In some cases (if “Route 2 H ” is adopted for the "hardware safety integrity constraints”), this is even a requirement. This paper presents how to estimate the failure rates from field feedback with confidence intervals, depending if the failures are detected on-line (called "detected failures", e.g. by automatic diagnostic tests) or only revealed by proof tests (called "undetected failures"). Examples show that for the same duration and number of failures observed, the estimated failure rates are basically higher for “undetected failures” because, in this case, the duration observed includes intervals of time where it is unknown that the elements have failed. This points out the need of using a proper approach for failure rates estimation, especially for failures that are not detected on-line. Then, this paper proposes an approach to use the estimated failure rates, with their uncertainties, for PFDavg and PFH assessment with upper confidence bounds, in accordance with IEC 61508 and IEC 61511 requirements. Examples finally show that the highest SIL that can be claimed for a safety function can be limited by the 90% upper confidence bound of PFDavg or PFH. The requirements of the IEC 61508 and IEC 61511 relating to the data collection and analysis should therefore be properly considered for the study of all safety-related systems. [ABSTRACT FROM AUTHOR]

• Discusses on the concepts of failure, including Root Cause Analysis, Diagnosis and Prognostic, Degradation, and Remaining Useful Life. • Investigates the process and methods for estimating the failure rate and the contributing factors. • Reviews the literature on failure rate estimation and modeling methods. • Identifies the challenges in equipment failure rate estimation. The evolution of the organizational attitudes regarding strategic management of system physical assets and the emergence of new technologies call for special attention to maintenance and reliability. State-of-the-art literature suggested a number of techniques and strategies for estimating the equipment failure rates; however, paralyzed by lack of real-world data, existing literature mostly relied on simplifications that may bring about unique challenges and result in low-accuracy estimations. This paper reviews the existing literature in estimating and modeling the failure rate of power system equipment. The review includes the existing models and the ongoing research on degradation, prognostic and estimation of remaining useful life of the system equipment. The advantages, limitations, and applications of the subject are explored in detail enabling new pathways for future research. [ABSTRACT FROM AUTHOR]