Failure rate,return-to-sports and magnetic resonance imaging after meniscal repair:119 patients with 7 years mean follow up

BACKGROUND One of the most important factors to consider in relation to meniscal repair is the high failure rate reported in the existing literature.AIM To evaluate failure rates,return to sports(RTS)rate,clinical outcomes and magnetic resonance image(MRI)evaluation after meniscus suture repair for longitudinal tears at a minimum 2-year-follow-up.METHODS We conducted a retrospective review of meniscal repairs between January 2004 and December 2018.All patients treated for longitudinal tears associated or not with an anterior cruciate ligament reconstruction(ACL-R)were included.Meniscal ramp lesions,radial and root tears,associated with multiligament injuries,tibial fracture and meniscal allograft transplants were excluded.Surgical details and failure rate,defined as symptomatic patients who underwent a revision surgery,were analyzed.As isolated bucket handle tears(BHTs)were usually associated with higher failure rates,we compared BHTs and not BHTs associated or not with an ACL-R.Since 2014,the inside-out technique using cannulas and suture needles with 2-0 Tycron began to predominate.In addition,the number of stitches per repair was increased.In view of differences in surgical technique,we compared two different cohorts:before and after 2014.We recorded the RTS according to the level achieved and the time to RTS.Lysholm and IKDC scores were recorded.Patients were studied with x-rays and MRI as standard postoperative control.RESULTS One hundred and nineteen patients were included with a mean follow up of 7 years(SD:4.08).Overall failure rate was 20.3%at a mean 20.1 mo.No statistically significant differences were found when comparing failure for medial and lateral meniscal repair(22.7%and 15.3%,P=0.36),BHTs and not BHTs(26%and 17.6%,P=0.27),isolated or associated with an ACL-R(22.9%and 18%,P=0.47),or when comparing only BHTs associated with an ACL-R(23%and 27.7%,P=0.9)or not.When comparing cohorts before and after 2014,we found a significant decrease in the overall failure rate from 26%to 11%(P<0.03).Isolated lesions presented a decrease from 28%to 6.6%(P=0.02),BHTs from 34%to 8%(P=0.09)and those associated with an ACL-R from 25%to 10%(P=0.09).Mean RTS time was 6.5 mo in isolated lesions and 8.64 mo when associated with an ACL-R.Overall,56%of patients returned to the same sport activity level.Mean pre and postoperative Lysholm scores were 64 and 85(P=0.02),and IKDC 58 and 70(P=0.03).Out of 84 asymptomatic patients evaluated with MRI,39%were classified as“not healed”and 61%as“healed”.CONCLUSION Even though the overall failure rate of our series was 20.3%,we found a statistically significant decrease from 26%to 11%,not only for isolated lesions,but also for BHT’s and those associated with an ACL-R when comparing our series in two different cohorts,most probably due to improvements in surgical technique.

Modeling the Failure Rate of a Standby Multi-Component System and Improving Reliability

Evaluating the reliability of a system requires knowledge of the failure modes to which it is subjected. Complex topology systems generally require a high level of availability, which is a function of the arrangement of elements (components) in the system. To avoid serious failures for such complex systems, recourse can be had to the redundancy techniques available in the literature. These techniques help to improve system reliability, without affecting the reliability of system components. This paper is interested in the proposal of a model for evaluating the failure rate of a standby multi-components system and in improving the reliability of mechanical systems, arranged in a topology (series, parallel, or mixed).

RELIABILITY ANALYSIS FOR A REPAIRABLE PARALLEL SYSTEM WITH TIME-VARYING FAILURE RATES

To solve a real problem:how to calculate the reliability of a system with time-varying failure rates in industry systems,this paper studies a model for the load-sharing parallel system with time-varying failure rates,and obtains calculating formulas of reliability and availability of the system by solving differential equations.In this paper,the failure rates are expressed in polynomial configuration.The constant,linear and Weibull failure rate are in their special form.The polynomial failure rates provide flexibility in modeling the practical time-varying failure rates.

Minimum 10-year follow-up outcomes of arthroscopic Bankart’s repair with metallic anchors:Reliable results with low redislocation rates

BACKGROUND With stiff competition from alternative albeit more expensive counterparts,it has become important to establish the applicability of metallic anchors for shoulder instability in the modern era.This can be accomplished,in part,by analysing long-term outcomes.AIM To analyse minimum 10-year outcomes from 30 patients following arthroscopic anterior stabilisation using metallic anchors.METHODS Prospectively collected data from arthroscopic Bankart repairs performed using metal anchors during 2007P-2010 were retrospectively analysed in this singlesurgeon study.Comprehensive data collection included historical and clinical findings,dislocation details,operative specifics,and follow-up radiological and clinical findings including shoulder scores.The primary outcomes were patientreported scores(Constant,American Shoulder and Elbow Surgeons[ASES],and Rowe scores)and pain and instability on a visual analogue scale(VAS).RESULTS A 3% recurrence rate of dislocation was noted at the final follow-up.Total constant scores at 10 years postoperatively measured between 76 and 100(mean 89)were significantly better than preoperative scores(mean 62.7).Congruous improvements were also noted in the Rowe and ASES scores and VAS at the 10-year review.CONCLUSION Reliable long-term outcomes with metallic anchors in surgery for shoulder instability can be expected.Our results provide additional evidence of their continued,cost-effective presence in the modern scenario.

Coordinating an Extended Warranty Supply Chain under Increasing,Constant and Decreasing Product Failure Rates

A product typically exhibits three different failure rates across its lifetime:increasing,decreasing,or constant.This paper studies how the characteristics of failure rate impact the supply chain coordination for an extended warranty program involving a manufacturer and a retailer.A two-stage Stackelberg game is utilized to model the interaction between these two players.Two extended warranty channel structures are compared depending on whether the manufacturer or the retailer offers the warranty service.The analysis shows that the failure rate trend during the warranty period has different effects on the coordination of the service supply chain.When a product has an increasing or constant failure rate,the optimal length of extended warranty offered by the retailer is longer than that of the manufacturer,while the optimal length is shorter for a product with a decreasing failure rate.If a product during the warranty coverage has an increasing or constant failure rate,a longer extended warranty period will motivate customers to buy the product without the warranty,whereas more customers will buy both the product and the warranty if the product experiences a decreasing failure rate.It is concluded that,if the manufacturer and the retailer incur the same warranty service cost,the total profit in the supply chain is higher when the manufacturer offers the extended warranty.From the game participants'perspective,the one which sells the extended warranty will obtain more profit.

A Novel Model of Failure Rate Prediction for Circular Electrical Connectors

The reliability of electrical connectors has critical impact on electronic systems. It is usually characterized by failure rate prediction value according to standard MIL-HDBK-217(or GJB-299 C in Chinese) in engineering practice. Given to their limitations and mislead results, a new failure rate prediction models needs to be presented. The presented model aims at the mechanism of increase of film thickness which leads to the increase of contact resistance. The estimated failure rate value can be given at different environmental conditions,and some of the factors affecting the reliability are taken into account. Accelerated degradation test(ADT) was conducted on GJB599 III series electrical connector. The failure rate prediction model can be simply formed and convenient to calculate the expression of failure rate changing with time at various temperature and vibration conditions. This model gives an objective assessment in short time, which makes it convenient to be applied to the engineering.

Bayesian and Non-Bayesian Analysis for the Sine Generalized Linear Exponential Model under Progressively Censored Data

This article introduces a novel variant of the generalized linear exponential(GLE)distribution,known as the sine generalized linear exponential(SGLE)distribution.The SGLE distribution utilizes the sine transformation to enhance its capabilities.The updated distribution is very adaptable and may be efficiently used in the modeling of survival data and dependability issues.The suggested model incorporates a hazard rate function(HRF)that may display a rising,J-shaped,or bathtub form,depending on its unique characteristics.This model includes many well-known lifespan distributions as separate sub-models.The suggested model is accompanied with a range of statistical features.The model parameters are examined using the techniques of maximum likelihood and Bayesian estimation using progressively censored data.In order to evaluate the effectiveness of these techniques,we provide a set of simulated data for testing purposes.The relevance of the newly presented model is shown via two real-world dataset applications,highlighting its superiority over other respected similar models.

Reliability-BasedModel for Incomplete Preventive ReplacementMaintenance of Photovoltaic Power Systems

At present,the operation and maintenance of photovoltaic power generation systems mainly comprise regular maintenance,breakdown maintenance,and condition-based maintenance,which is very likely to lead to over-or under-repair of equipment.Therefore,a preventive maintenance and replacement strategy for PV power generation systems based on reliability as a constraint is proposed.First,a hybrid failure function with a decreasing service age factor and an increasing failure rate factor is introduced to describe the deterioration of PV power generation equipment,and the equipment is replaced when its reliability drops to the replacement threshold in the last cycle.Then,based on the reliability as a constraint,the average maintenance cost and availability of the equipment are considered,and the non-periodic incomplete maintenance model of the PV power generation system is established to obtain the optimal number of repairs,each maintenance cycle and the replacement cycle of the PV power generation system components.Next,the inverter of a PV power plant is used as a research object.The model in this paper is compared and analyzed with the equal cycle maintenance model without considering reliability and the maintenance model without considering the equipment replacement threshold,Through model comparison,when the optimal maintenance strategy is(0.80,4),the average maintenance cost of this paper’s model are decreased by 20.3%and 5.54%and the availability is increased by 0.2395% and 0.0337%,respectively,compared with the equal-cycle maintenance model without considering the reliability constraint and the maintenance model without considering the equipment replacement threshold.Therefore,this maintenance model can ensure the high reliability of PV plant operation while increasing the equipment availability to improve the system economy.

Bayesian serial revision method for RLLC cluster systems failure prediction

Failure prediction plays an important role for many tasks such as optimal resource management in large-scale system. However, accurately failure number prediction of repairable large-scale long-running computing （RLLC） is a challenge because of the reparability and large-scale. To address the challenge, a general Bayesian serial revision prediction method based on Bootstrap approach and moving average approach is put forward, which can make an accurately prediction for the failure number. To demonstrate the performance gains of our method, extensive experiments on the data of Los Alamos National Laboratory （LANL） cluster is implemented, which is a typical RLLC system. And experimental results show that the prediction accuracy of our method is 80.2 %, and it is a greatly improvement with 4 % compared with some typical methods. Finally, the managerial implications of the models are discussed.

Mathematical Modeling and Evaluation of Reliability Parameters Based on Survival Possibilities under Uncertain Environment

In this article,mathematical modeling for the evaluation of reliability is studied using two methods.One of the methods,is developed based on possibility theory.The performance of the reliability of the system is of prime concern.In view of this,the outcomes for the failure are required to evaluate with utmost care.In possibility theory,the reliability information data determined from decision-making experts are subjective.The samemethod is also related to the survival possibilities as against the survival probabilities.The other method is the one that is developed using the concept of approximation of closed interval including the piecewise quadratic fuzzy numbers.In this method,a decision-making expert is not sure of his/her estimates of the reliability parameters.Numerical experiments are performed to illustrate the efficiency of the suggested methods in this research.In the end,the paper is concluded with some future research directions to be explored for the proposed approach.

Time-dependent Vibration Frequency Reliability Analysis of Blade Vibration of Compressor Wheel of Turbocharger for Vehicle Application

Blade vibration failure is one of the main failure modes of compressor wheel of turbocharger for vehicle application. The existing models for evaluating the reliability of blade vibration of compressor wheel are static, and can not reflect the relationship between the reliability of compressor wheel with blade vibration failure mode and the life parameter. For the blade vibration failure mode of compressor wheel of turbocharger, the reliability evaluation method is studied. Taking a compressor wheel of turbocharger for vehicle application as an example, the blade vibration characteristics and how they change with the operating parameters of turbocharger are analyzed. The failure criterion for blade vibration mode of compressor wheel is built with the Campbell diagram, and taking the effect of the dispersity of blade natural vibration frequency and randomness of turbocharger operating speed into account, time-dependent reliability models of compressor wheel with blade vibration failure mode are derived, which embody the parameters of blade natural vibration frequency, turbocharger operating speed, the blade number of compressor wheel, life index and minimum number of resonance, etc. Finally, the rule governing the reliability and failure rate of compressor wheel and the method for determining the reliable life of compressor with blade vibration is presented. A method is proposed to evaluate the reliability of compressor wheel with blade vibration failure mode time-dependently.

Risk Analysis and Assessment of Overtopping Concerning Sea Dikes in the Case of Storm Surge

Risk analysis and assessment relating coastal structures has been one of the hot topics in the area of coastal protection recently. In this paper, from three aspects of joint return period of multiple loads, dike failure rate and dike continuous risk prevention respectively, three new risk analysis methods concerning overtopping of sea dikes are developed. It is worth noting that the factors of storm surge which leads to overtopping are also considered in the three methods. In order to verify and estimate the effectiveness and reliability of the newly developed methods, quantified mutual information is adopted. By means of case testing, it can be found that different prior variables might be selected dividedly, according to the requirement of special engineering application or the dominance of loads. Based on the selection of prior variables, the correlating risk analysis method can be successfully applied to practical engineering.

Load Dependent Series-Parallel Systems with Common Bus Performance Sharing Mechanism

A series-parallel system was proposed with common bus performance sharing in which the performance and failure rate of the element depended on the load it was carrying. In such a system,the surplus performance of a sub-system can be transmitted to other deficient sub-systems. The transmission capacity of the common bus performance sharing mechanism is a random variable. Effects of load on element performance and failure rate were considered in this paper. A reliability evaluation algorithm based on the universal generating function technique was suggested. Numerical experiments were conducted to illustrate the algorithm.

Reliability Indices Evaluation of LV Distribution System and Inclusion of Protective Devices for Reliability Improvement

This paper analyzes the reliability of low voltage(LV)distribution system of the Sri Lankan power system.Performance of LV distribution systems where mainly domestic consumers depend on the individual components of the system.Failure rates of elements of the system are calculated based on the historical data of the LV distribution system in a semi-urban area.Load point reliability indices are calculated using the analytical method.Consumer-oriented reliability parameters and energy not served,and its cost are determined.As a method of improvement of reliability,inclusion of fuses to the lateral feeders of the main feeder is proposed.Load point reliability indices,consumer-oriented reliability indices,and energy not served are calculated for the distribution system with fuses in lateral feeders.The results are compared with the reliability indices of the present system and analyzed.

A Method for Determining the Reliability Index of a Materiel Subsystem

This paper presents a method for determining the reliability index of a subsystem in the materiel demonstration phase-AHP Failure Rate Method. It fully considers the various factors which influence a subsystem reliability index and solves a difficult problem that puzzles the demonstration personnel.

Estimation of Reliability and Cost Relationship for Architecture-based Software

In this paper, wc propose a new method to estimate the relationship between software reliability and software development cost taking into account the complexity for developing the software system and the size of software intended to develop during the implementation phase of the software development lifc cycle. On the basis of estimated relationship, a set of empirical data has been used to validate the correctness of the proposed model by comparing the result with the other existing models. The outcome of this work shows that the method proposed here is a relatively straightforward one in formulating the relationship between reliability and cost during implementation phase.

CONTRACEPTIVE PREVALENCE AND USE－EFFECTIVENESS OF MARRIED WOMEN OF REPRODUCTIVE AGE IN THE RURAL AREAS OF SHAANXI PROVINCE

In order to study women's fertility and behavior in shaanxi Province, we used PPS method to sample Weinan, Nanzheng and Yan'an counties which represent the centre, south and north of Shaanxi respectively from February to March in 1990. 3253 qualified married women of reproductive age were available. Because contraception is one of the most imPOrtant proximate determinants in inhibiting fertility, we just measured contraceptive prevalence and use-effectiveness among different subgroups in this dissertation. The results indicated that the prevalence rate of contraception was 75. 9 %, prevalence of different contraceptive methods varied widely: it was 43. 5% in IUD, 27. 7% in women'sterilization, 2. 0% in pill, 1.9% in men's sterilization, 0. 2% in condom and 0. 7 % in other methods, The average use-effectiveness of three methods was 0. 9965 for sterilization,0. 8792 for IUD and 0. 8520 for other methods and total average use-effectiveness was 0. 9251.

The Mean Residual Lifetime of (n-k+1)-out-of-n;Systems in Discrete Setting

In real life, there are situations in which the lifetime of the components of a technical system (and hence the lifetime of the system) is discrete. In this paper, we study the residual life, a (n - k + 1)-out-of-n system under the assumptions that the components of the system are independent identically distributed with common discrete distribution function F. We define the mean residual lifetime (MRL) of the system and under different scenarios investigate several aging and stochastic properties of MRL.

A Modification of the Quasi Lindley Distribution

In this paper, we introduce a modification of the Quasi Lindley distribution which has various advantageous properties for the lifetime data. Several fundamental structural properties of the distribution are explored. Its density function can be left-skewed, symmetrical, and right-skewed shapes with various rages of tail-weights and dispersions. The failure rate function of the new distribution has the flexibility to be increasing, decreasing, constant, and bathtub shapes. A simulation study is done to examine the performance of maximum likelihood and moment estimation methods in its unknown parameter estimations based on the asymptotic theory. The potentiality of the new distribution is illustrated by means of applications to the simulated and three real-world data sets.

Assessment of Operating Condition Dependent Reliability Indices in Microgrids

Reliability results are important for proper planning and operation of utility companies. At the base of this method of analysis is the failure rate of the system components. In the traditional method, this probability of failure is determined by the components’ manufacturer and is considered to be constant. This study proposes a dynamic modeling of failure rate, taking the system operating conditions into consideration. With this new consideration, an IEEE test system has seven of its reliability indices quantified for comparison. The inclusion of the newly modeled failure rate leads to a worsening of 11.07% in the indices, on average. A second analysis is performed considering the presence of DG sources within the microgrid, namely PV and wind based. An improvement of 0.71% on the indices is noticed, once the DG sources are introduced. Finally, the effects of storage systems in the microgrid are investigated through a third scenario, in which two 2 MWh battery systems are introduced, and an improvement of 3.05% is noticed in the reliability indices.