Engineering approach for human error probability quantification

A novel approach for engineering application to human error probability quantification is presented based on an overview of the existing human reliability analysis methods. The set of performance shaping factors is classified as two subsets of dominant factors and adjusting factors respectively. Firstly, the dominant factors are used to determine the probabilities of three behavior modes. The basic probability and its interval of human error for each behavior mode are given. Secondly, the basic probability and its interval are modified by the adjusting factors, and the total probability of human error is calculated by a total probability formula. Finally, a simple example is introduced, and the consistency and validity of the presented approach are illustrated.

Human eye ocular component analysis for refractive state and refractive surgery

AIM： To analyze the clinical factors influencing the human vision corrections via the changing of ocular components of human eye in various applications; and to analyze refractive state via a new effective axial length.METHODS： An effective eye model was introduced by the ocular components of human eye including refractive indexes, surface radius（r1, r2, R1, R2） and thickness（t, T） of the cornea and lens, the anterior chamber depth（S1） and the vitreous length（S2）. Gaussian optics was used to calculate the change rate of refractive error per unit amount of ocular components of a human eye（the rate function M）. A new criterion of myopia was presented via an effective axial length.RESULTS： For typical corneal and lens power of 42 and 21.9 diopters, the rate function Mj（j=1 to 6） were calculated for a 1% change of r1, r2, R1, R2, t, T（in diopters） M1=＋0.485, M2=-0.063, M3=＋0.053, M4=＋0.091, M5=＋0.012, and M6=-0.021 diopters. For 1.0 mm increase of S1 and S2, the rate functions were M7=＋1.35, and M8=-2.67 diopter/mm, respectively. These rate functions were used to analyze the clinical outcomes in various applications including laser in situ keratomileusis surgery, corneal cross linking procedure, femtosecond laser surgery and scleral ablation for accommodation.CONCLUSION： Using Gaussian optics, analytic formulas are presented for the change of refractive power due to various ocular parameter changes. These formulas provide useful clinical guidance in refractive surgery and other related procedures.

Bayesian estimator of human error probability based on human performance data

A Bayesian method for estimating human error probability（HEP） is presented.The main idea of the method is incorporating human performance data into the HEP estimation process.By integrating human performance data and prior information about human performance together,a more accurate and specific HEP estimation can be achieved.For the time-unrelated task without rigorous time restriction,the HEP estimated by the common-used human reliability analysis（HRA） methods or expert judgments is collected as the source of prior information.And for the time-related task with rigorous time restriction,the human error is expressed as non-response making.Therefore,HEP is the time curve of non-response probability（NRP）.The prior information is collected from system safety and reliability specifications or by expert judgments.The（joint） posterior distribution of HEP or NRP-related parameter（s） is constructed after prior information has been collected.Based on the posterior distribution,the point or interval estimation of HEP/NRP is obtained.Two illustrative examples are introduced to demonstrate the practicality of the aforementioned approach.

Handling Uncertainty in Human Cognitive Reliability Method for Safety Assessment Based on DSET

Human Reliability Analysis(HRA)is an important part in safety assessment of a large complex system.Human Cognitive Reliability(HCR)model is a method of evaluating the probability that operators fail to complete during diagnostic decision making within a limited time,which is widely used in HRA.In the application of this method,cognitive patterns of humans are required to be considered and classified,and this process often relies on the evaluation opinions of experts which is highly subjective and uncertain.How to effectively express and process this uncertain and subjective information plays a critical role in improving the accuracy and applicability of HCR.In this paper,a new model was proposed to deal with the uncertain information which exists in the processes of cognitive pattern classification in HCR.First,an evaluation panel was constructed based on expert opinions and processing including setting corresponding anchor points and qualitative indicators of different cognitive patterns,and mapping them to fuzzy numbers and unit intervals.Second,based on the evaluation panel,different analysts judge the cognitive pattern types of actual specific events and provide the level of confidence he or she has in the judgments.Finally,the evaluation opinions of multiple analysts were expressed and fused based on the Dempster-Shafer Evidence Theory(DSET),and the fused results were applied to the HCR model to obtain the Human Error Probability(HEP).A case study was used to demonstrate the procedure and effectiveness of the proposed method.

The traps behind the failure of Malpasset arch dam,France,in 1959

The case of the Malpasset arch dam failure in 1959 has been widely exposed in scientifc and technical forums and papers.The focus here is on the many traps which have confused the whole chain of bodies and persons involved,owner,designer,geologist,contractor,up to the state management offcers.When the frst traps were hidden inside geology,many more appeared,as well geotechnical,technical,fortuitous,and administrative.In addition to such factual factors,human and organizational factors may be today easily identifed,when none of them was yet suspected.Both dam safety and rock mechanics benefted from the studies done since the Malpasset case,most of them within one decade.

Estimation of Probability of Damage Detection in Offshore Structural Inspection

To characterize the uncertainty and fuzziness in offshore structural inspection, probability of detection (POD) must be determined. This paper presents the expressions for the POD of four different damage forms mainly existing in offshore structures. The fuzzy-set theory is applied to estimate human errors through the definition of inspection quality. Expressions of inspection quality are achieved. To verify the validity and correctness of the expressions, the data from an offshore platform field inspection of evaluation results of human errors affecting inspection quality are used to estimate the parameters of the POD. The results show that the present models can provide basis for further study of ofTshore structural inspection reliability.

船用柴油机辅助系统关键故障人因失误概率评估

Human error,an important factor,may lead to serious results in various operational fields.The human factor plays a critical role in the risks and hazards of the maritime industry.A ship can achieve safe navigation when all operations in the engine room are conducted vigilantly.This paper presents a systematic evaluation of 20 failures in auxiliary systems of marine diesel engines that may be caused by human error.The Cognitive Reliability Error Analysis Method(CREAM)is used to determine the potentiality of human errors in the failures implied thanks to the answers of experts.Using this method,the probabilities of human error on failures were evaluated and the critical ones were emphasized.The measures to be taken for these results will make significant contributions not only to the seafarers but also to the ship owners.

Analysis of Critical Incidents during Anesthesia in a Tertiary Hospital

Introduction: Critical incident monitoring is important in quality improvement as it identifies potential risks to patients by analyzing adverse events or near-misses. Methods: This study analyses the reported incidents in a tertiary hospital over a 4-year period. Results: A total of 441 incidents were reported out of 98,502 anesthetics performed during the study period. Of these incidents, 67 resulted in no harm caused, 116 with unanticipated ICU admissions and 20 mortalities. The odds of having a critical incident increased with ASA status: from an odds ratio of 2.08 (95% CI: 1.58 to 2.74) for ASA 2 patients compared to ASA1, to OR of 13.70 (5.91 to 31.74) in ASA 5 compared to ASA 1. Critical incidents also have higher odds occurring out of hours (OR 1.7 (1.45 to 2.23) compared to daytime hours (08:00-17:00). They occurred most commonly in maintenance phase (142, 32.7%), followed by induction (120, 27.6%). The most common types of incidents include airway and respiratory (110, 24.9%) followed by drug related incidents (67, 15.2%). Human error was attributed as a significant contributing factor in 276 incidents (61.5%) followed by patient factors in 112 incidents (25.4%). Mitigating factors such as vigilance by staff involved were significant in 136 incidents (30.3%). Conclusion: Higher ASA status appears to be the most important factor associated with actual or potential patient harm in our study. Also significant, was time of incident, with incidents more likely out of hours. Critical incident reporting is a valuable part of quality assurance. We should continue to invest in incident reporting, incident analysis and improvement plans.

The Impact of Maritime Accidents on the Autonomous Ships Proving Their Missions in the Future

The main issue is figuring out how to make it work within the rules.Instead of relying on crew,shipping companies could make more money,by reducing manpower expenses and increasing cargo transport volumes,while the entire industry could become safer by eliminating the human factor that contributes so much to accidents.New threats and errors will arise,but they can be as a minimum equalized or even reduced compared to the existing ones,so we can have more reliable ships without putting lives at risk.The main goal is to identify the most common ships accidents type,as well as the most common types of ships that cause accidents,which could have an impact on the future of autonomous ships.There is also a way to gain access to human error,education and training,and how to deal with weaknesses in the future of these ships.This research is based on a descriptive approach,as this methodology is the most capable of providing a comprehensive picture of the efficiency of the new technology.

Method of Estimating Human Error Probabilities in Construction for Structural Reliability Analysis Based on Analytic Hierarchy Process and Failure Likelihood Index Method

Human error(HE) is the most important factor influencing on structural safety because its effect often exceeds the random deviation.Large numbers of facts have shown that structural failures may be caused by the gross error due to HE.So it is essential to analyze HE in construction.The crucial work of human error analysis(HEA) is the estimation of human error probability(HEP) in construction.The method for estimating HEP,analytic hierarchy process and failure likelihood index method(AHP-FLIM),is introduced in this paper.The method also uses the process of expert judgment within the failure likelihood index method(FLIM).A numerical example shows the effectiveness of the methods proposed.

Software defect prevention based on human error theories

Software defect prevention is an important way to reduce the defect introduction rate.As the primary cause of software defects,human error can be the key to understanding and preventing software defects.This paper proposes a defect prevention approach based on human error mechanisms：DPe HE.The approach includes both knowledge and regulation training in human error prevention.Knowledge training provides programmers with explicit knowledge on why programmers commit errors,what kinds of errors tend to be committed under different circumstances,and how these errors can be prevented.Regulation training further helps programmers to promote the awareness and ability to prevent human errors through practice.The practice is facilitated by a problem solving checklist and a root cause identification checklist.This paper provides a systematic framework that integrates knowledge across disciplines,e.g.,cognitive science,software psychology and software engineering to defend against human errors in software development.Furthermore,we applied this approach in an international company at CMM Level 5 and a software development institution at CMM Level 1 in the Chinese Aviation Industry.The application cases show that the approach is feasible and effective in promoting developers＇ ability to prevent software defects,independent of process maturity levels.

Modeling and simulating the impact of forgetting and communication errors on delays in civil infrastructure shutdowns

Handoff processes during civil infrastructure operations are transitions between sequential tasks.Typical handoffs constantly involve cognitive and communication activities among operations personnel,as well as traveling activities.Large civil infrastructures,such as nuclear power plants(NPPs),provide critical services to modem cities but require regular or unexpected shutdowns(i.e.,outage)for maintenance.Handoffs during such an outage contain interwoven workflows and communication activities that pose challenges to the cognitive and communication skills of handoff participants and constantly result in delays.Traveling time and changing field conditions bring additional challenges to effective coordination among multiple groups of people.Historical NPP records studied in this research indicate that even meticulous planning that takes six months before each outage could hardly guarantee sufficient back-up plans for handling various unexpected events.Consequently,delays frequently occur in NPP outages and bring significant socioeconomic losses.A synthesis of previous studies on the delay analysis of accelerated maintenance schedules revealed the importance and challenges of handoff modeling.However,existing schedule representation methods could hardly represent the interwoven communication,cognitive,traveling,and working processes of multiple participants collaborating on completing scheduled tasks.Moreover,the lack of formal models that capture how cognitive,waiting,traveling,and communication issues affect outage workflows force managers to rely on personal experiences in diagnosing delays and coordinating multiple teams involved in outages.This study aims to establish formal models through agent-based simulation to support the analytical assessment of outage schedules with full consideration of cognitive and communication factors involved in handoffs within the NPP outage workflows.Simulation results indicate that the proposed handoff modeling can help predict the impact of cognitive and communication issues on delays propagating throughout outage schedules.Moreover,various activities are flilly considered,including traveling between workspaces and waiting.Such delay prediction capability paves the path toward predictive and resilience outage control of NPPs.

Determination of Partial Safety Coefficients of Structural Reliability Based on Contaminated Distribution

Partial safety factors must be evaluated precisely for the given target reliability index to ensure the certain level of structural reliability due to uncertain factors.The current studies of partial safety factors do not consider human error in construction for structural reliability.A mathematically model should be improved to simulate the partial safety coefficient concerned uncertainty factors which concern the effect of human error in construction.We employ the contaminated distribution to obtain the realistic mean value and standard variance of variable of structural parameters which coexist with random error human error.The reasonable partial safety coefficient can be calculated based on the realistic value of structural parameters concerned the effects of random error and gross error.