A STAMP-Game model for accident analysis in oil and gas industry

Accidents in engineered systems are usually generated by complex socio-technical factors.It is beneficial to investigate the increasing complexity and coupling of these factors from the perspective of system safety.Based on system and control theories,System-Theoretic Accident Model and Processes(STAMP)is a widely recognized approach for accident analysis.In this paper,we propose a STAMP-Game model to analyze accidents in oil and gas storage and transportation systems.Stakeholders in accident analysis by STAMP can be regarded as players of a game.Game theory can,thus,be adopted in accident analysis to depict the competition and cooperation between stakeholders.Subsequently,we established a game model to study the strategies of both supervisory and supervised entities.The obtained results demonstrate that the proposed game model allows for identifying the effectiveness deficiency of the supervisory entity,and the safety and protection altitudes of the supervised entity.The STAMP-Game model can generate quantitative parameters for supporting the behavior and strategy selections of the supervisory and supervised entities.The quantitative data obtained can be used to guide the safety improvement,to reduce the costs of safety regulation violation and accident risk.

Application of cluster analysis to preventive maintenance scheme design of pavement

To quantitatively identify the maintenance demand for each highway segments in the pavement maintenance scheme design,a mathematical model of uniform segment division was established and an approach of applying cluster analysis theory to the uniform segment division and evaluation of pavement maintenance demand was proposed.The actual maintenance project of a highway carried out in Guangdong province was cited as an example to demonstrate the validity of the proposed method.It is proved that the cluster analysis can eliminate human factors in classification without being constrained by the quantities of samples,considering multiple pavement distress indexes and the continuity of samples.Thus it is evident that cluster analysis is an efficient analytical tool in uniform segment division and evaluation of maintenance demand.

Efficiency Evaluation for the Annual Equipment Maintenance Based on Set Pair Analysis

Most traditional assessment methods, which have complicated mathematic formulas,are difficult for calculation and application in system efficiency evaluation. A new approach to annual equipment maintenance system efficiency assessment,the set pair analysis method( SPAM),has been proposed based on the principle of set pair analysis( SPA). Firstly,the evaluation index system of the annual equipment maintenance is proposed. Secondly,the evaluation model of the annual equipment maintenance efficiency based on the SPAM is built. Then the application processes of the SPAM are introduced. At the end of the paper,a real application example is given. The results of the application indicate that the proposed model is feasible and effective. It can give strong supports to improve the evaluation effect of the unit equipment maintenance support.

Fault Analysis and Maintenance of DZZ Series of Automatic Weather Stations

The instruments of regional automatic weather station are placed outside to measure daily changes of meteorological factors. Due to common influence of sun,wind,rain and other factors,it is very easy to cause various faults and damages of the instrument. The construction of regional automatic weather station network plays an important role in improving forecast accuracy,servicing local government and ecological civilization construction,providing scientific disaster prevention and relief decision-making basis for government department. In this paper,based on daily operation situation of regional automatic weather station in Shaoyang region,combining communication,hardware and software,fault situation of collector,temperature and humidity sensor,wind sensor and rainfall sensor in automatic weather station is analyzed in detail. Moreover,some common fault cases are listed and analyzed,some troubleshooting methods are summarized,and daily maintenance measures are proposed.

Calculation of Empirical and True Maintenance Coefficients by Flux Balance Analysis

The stoichiometric matrix of a simplified metabolic network inBacillus Subtillis was constructed from the flux balance equations,which were used for reconciliation of the measured rates anddetermination of the inner metabolic rates. Thus more reliableresults of the true and empirical maintenance coefficients wereobtained. The true maintenance coefficient is linearly related to thespecific growth rate and changes with the P/O ratio. The measuredbiomass yield of adenosine triphosphate (ATP) is also linearlyrelated to the P/O ratio.

Risk analysis and maintenance decision making of natural gas pipelines with external corrosion based on Bayesian network

Buried natural gas pipelines are vulnerable to external corrosion because they are encased in a soil environment for a long time.Identifying the causes of external corrosion and taking specific maintenance measures is essential.In this work,a risk analysis and maintenance decision-making model for natural gas pipelines with external corrosion is proposed based on a Bayesian network.A fault tree model is first employed to identify the causes of external corrosion.The Bayesian network for risk analysis is determined accordingly.The maintenance strategies are then inserted into the Bayesian network to show a reduction of the risk.The costs of maintenance strategies and the reduced risk after maintenance are combined in an optimization function to build a decision-making model.Because of the limitations of historical data,some of the parameters in the Bayesian network are obtained from a probabilistic estimation model,which combines expert experience and fuzzy set theory.Finally,a case study is carried out to verify the feasibility of the maintenance decision model.This indicates that the method proposed in this work can be used to provide effective maintenance schemes for different pipeline external corrosion scenarios and to reduce the possible losses caused by external corrosion.

Concordance between bio-impedance analysis and clinical score in fluid-status assessment of maintenance haemodialysis patients: A single centre experience

BACKGROUND The burden of chronic kidney disease(CKD)is rising rapidly globally.Fluid overload(FO),an independent predictor of mortality in CKD,should be accurately assessed to guide estimation of the volume of fluid to be removed during haemodialysis(HD).Clinical score(CS)and bio-impedance analysis(BIA)have been utilized in assessment of FO and BIA has demonstrated reproducibility and accuracy in determination of fluid status in patients on HD.There is need to determine the performance of locally-developed CSs in fluid status assessment when evaluated against BIA.AIM To assess the hydration status of patients on maintenance HD using BIA and a CS,as well as to evaluate the performance of that CS against BIA in fluid status assessment.METHODS This was a single-centre,hospital-based cross-sectional study which recruited adult patients with CKD who were on maintenance HD at Kenyatta National Hospital.The patients were aged 18 years and above and had been on maintenance HD for at least 3 mo.Those with pacemakers,metallic implants,or bilateral limbs amputations were excluded.Data on the patients’clinical history,physical examination,and chest radiograph findings were collected.BIA was performed on each of the study participants using the Quantum®II bio-impedance analyser manufactured by RJL Systems together with the BC 4®software.In evaluating the performance of the CS,BIA was considered as the gold standard test.A 2-by-2 table of the participants’fluid status at each of the CS values obtained compared to their paired BIA results was constructed(either++,+-,--or-+for FO using the CS and BIA,respectively).The results from this 2-by-2 table were used to compute the sensitivity and specificity of the CS at the various reference points and subsequently plot a receiver operating characteristic(ROC)curve that was used to determine the best cut-off point.Those above and below the best CS cut-off point as determined by the ROC were classified as being positive and negative for FO,respectively.The proportions of participants diagnosed with FO by the CS and BIA,respectively,were computed and summarized in a 2-by-2 contingency table for comparison.McNemar’s chi-squared test was used to assess any statistically significant difference in proportions of patients diagnosed as having FO by CS and BIA.Logistic regression analysis was conducted to assess whether the variables for the duration of dialysis,the number of missed dialysis sessions,advisement by health care professional on fluid or salt intake,actual fluid intake,the number of anti-hypertensives used,or body mass index were associated with a patient’s odds of having FO as diagnosed by BIA.RESULTS From 100 patients on maintenance HD screened for eligibility,80 were recruited into this study.Seventy-one(88.75%)patients were fluid overloaded when evaluated using BIA with mean extracellular volume of 3.02±1.79 L as opposed to the forty-seven(58.25%)patients who had FO when evaluated using the CS.The difference was significant,with a P value of<0.0001(95%confidence interval:0.1758-0.4242).Using CS,values above 4 were indicative of FO while values less than or equal to 4 denoted the best cut-off for no FO.The sensitivity and specificity for the CS were 63%and 78%respectively.None of the factors evaluated for association with FO showed statistical significance on the multivariable logistic regression model.CONCLUSION FO is very prevalent in patients on chronic HD at the Kenyatta National Hospital.CS detects FO less frequently when compared with BIA.The sensitivity and specificity for the CS were 63%and 78%respectively.None of the factors evaluated for association with FO showed statistical significance on the multivariable logistic regression model.

Statistical Safety Analysis of Maintenance Management Process of Excavator Units

Within this paper, the process of statistical safety analysis has been presented, which involves the following steps： formulation of basic principles of statistical safety analysis, initial events analysis, accident sceneries progress analysis, risk calculation, and risk calculation results analysis. On this basis, it has been concluded that the bucket wheel excavator SRs 1200×24/4×0（400 kW）＋VR safety criteria is the mechanism for the hoist of rotor＇s arrow failure modes, because in that case whole bucket wheel excavator failure would necessarily happen （excavator falling down on counterweight）. Therefore, excavator units statistical safety analysis is accomplished preventively to obtain its effective maintenance management.

Evaluating and Improving the Effectiveness of Vehicle Inspection and Maintenance Programs: A Cost-Benefit Analysis Framework

Motor vehicle inspection and maintenance (I/M) programs are designed to identify high-emitting vehicles and mitigate their impacts on air quality and climate. I/M programs have been traditionally ranked superior among various vehicle emission control measures by the results of cost-benefit analysis, based on the assumption that these programs will achieve the targeted emission reduction outcomes. However, the actual effects of I/M programs may be greatly uncertain and when this uncertainty is taken into account, these programs may become suboptimal. This study develops a new a cost-benefit analysis framework that links various program design consideration, such as program participation rate, identification rate and effective repair rate, to the public health benefits as well as costs of the programs. This framework helps decision makers to investigate minimum implementation requirements that at least ensure the benefits are greater than the costs of implementing the programs in order to improve the overall effectiveness of the I/M programs. To illustrate the applications of the framework, it was applied to a particulate matter oriented I/M program targeting all diesel-fueled vehicles in the city of Bangkok, Thailand, a large metropolitan area that has been suffering from severe ambient PM pollution mainly attributable to its wide use of diesel-fueled vehicles and motorcycles. It was found that the health benefits achieved from the program are sensitive to several key program design elements, including participation rate and problem vehicle identification rate, fraction of effective repairs and illegal operation rate. Other variables, such as the testing cut-points and vehicle population growth rate, only have modest effects on the overall emission reduction and consequent health benefits. Overall, the performance of multiple variables associated with I/M program design needs to be improved simultaneous in order to achieve the targeted benefits of the program.

Sensitivity Analysis of Key Parameters in Decision Making of Two-Stage Evolutionary Optimization Maintenance Strategies

Preventative maintenance (PM) measures for bridges are proactive maintenance actions which aim to prevent or delay a deterioration process that may lead to failure. This type of maintenance can be justified on economic grounds since it can extend the life of the bridge and avoid the need for unplanned essential/corrective maintenance. Due to the high importance of the effective integration of PM measures in the maintenance strategies of bridges, the authors have developed a two-stage evolutionary optimization methodology based on genetic algorithm (GA) principles which links the probabilistic effectiveness of various PM measures with their costs in order to develop optimum PM strategies. In this paper, the sensitivity of the methodology to various key input parameters of the optimization methodology is examined in order to quantify their effects and identify possible trends in the optimum PM intervention profiles. The results of the sensitivity studies highlight the combined use of both proactive and reactive PM measures in deriving optimum strategy solutions. The precise mix and sequence of PM measures is clearly a function of the relative effectiveness and cost of the different available PM options as well as the various key parameters such as discount rate, target probability of failure, initial probability of failure and service life period examined. While the results highlight the need for more reliable data they also demonstrate the robustness and usefulness of the methodology;in the case where data is limited it can be used as a comparative tool to improve understanding of the effects of various strategies and enhance the decision making process.

Innovative Variables to Increase the Analysis of Maintenance of Industrial Equipment

In existing references,authors and companies have defined the maintenance variables over time;it is found that in some cases there are traditions,incorrect postulates or the inappropriate use of terminology,which leads to a misinterpretation of the results when maintenance management is analyzed.Starting from a documentary and deductive methodology,in this article,the analysis of some authors is presented and,from its origin,the initial variables that allow the construction of adequate algorithms for the maintenance function and to obtain the correct information related to it are re-defined.In a simple way with mathematical models,to then apply statistical models which allows,subsequently,calculating the maintenance information and achieving that professionals,professors and students are incorporated into maintenance analysis processes with a higher cognitive level,producing continuous information and comprehensive to analyze and investigate industrial equipment based on a basic history.

Analysis of Flower Border Design and Maintenance in the Later Period

Since the 21st century,China's economy has enjoyed rapid development and people's living standards have been improved.At the same time,the pursuit of beauty of people is getting increasingly higher and landscaping of and design of gardens has been widely pursued by people.This paper has discussed and analyzed the design of flower border and maintenance of flower border in the later period,hoping to provide some help and support for the relevant technical workers.

Development of Maintenance Management Strategy Based on Reliability Centered Maintenance for Marginal Oilfield Production Facilities

The present work adopted Reliability Centered Maintenance (RCM) methodology to evaluate marginal oilfield Early Production Facility (EPF) system to properly understand its functional failures and to develop an efficient maintenance strategy for the system. The outcome of the RCM conducted for a typical EPF within the Niger Delta zone of Nigeria provides an indication of equipment whose failure can significantly affect operations at the production facility. These include the steam generation unit and the wellhead choke assembly, using a risk-based failure Criticality Analysis. Failure Mode and Effect Analysis (FMEA) was conducted for the identified critical equipment on a component basis. Each component of the equipment was analyzed to identify the failure modes, causes and the effect of the failure. The outcome of the FMEA analysis aided the development of a robust maintenance management strategy, which is based on an optimized mix of corrective, preventive and condition-based monitoring maintenance for the marginal oilfield EPF.

SWOT Analysis of Urban Greening Maintenance and Management in the Central Pearl River Delta

We take Shunde District,Foshan City in Guangdong Province for example,to carry out SWOT analysis of urban greening maintenance and management.The strengths of greening management and maintenance in Shunde District are as follows:(i)The greening area and quality are continuously improved in the downtown of Shunde District;(ii)The management and maintenance work is carried out well;(iii)The management and maintenance level tends to be increasingly perfected.The weaknesses of greening management and maintenance are as follows:(i)The fees for greening management and maintenance are very low;(ii)There is corner as yet untouched in the junction of some town streets;(iii)The greening management and maintenance technicians are unprofessional;(iv)The greening management is not in place;(v)There is management vacancy phenomenon in the management and maintenance of regional green space;(vi)The design and construction phase is flawed.Finally,based on the analysis of strengths and weaknesses of greening,we put forth the recommendations for the development of management and maintenance in urban green space.

Statistical approach to determination of overhaul and maintenance cost of loading equipment in surface mining

The purpose of this research was to develop a new approach in determination of overhaul and maintenance cost of loading equipment in surface mining. Two statistical models including univariate exponential regression (UER) and multivariate linear regression (MLR) were used in this study. Loading equipment parameters such as bucket capacity, machine weight, engine power, boom length, digging depth, and dumping height were considered as variables. The results obtained by models and mean absolute error rate indicate that these models can be applied as the useful tool in determination of overhaul and maintenance cost of loading equipment. The results of this study can be used by the decision-makers for the specific surface mining operations.

Comparison of Economic Life of Tractors in Iran Using Condition Monitoring （CM） and Breakdown Maintenance （BM） Methods

Repair and maintenance costs are the most important factors affecting decision making about substituting agricultural machineries. This decision is made based on the economic life （time） of machineries. In this research, condition monitoring of MF285 and MF399 tractors was performed using engine oil analysis to find the optimum life time of tractor substitution in comparison with the breakdown maintenance method in Iran. All recorded information about fixed and variable costs were selected as data base and analyzed. Data were divided （classified） based on period of annual working time. Using power regression analysis led to find mathematical models for the optimum time life definition. Cumulative working time （X） was selected as independent and cumulative costs based on definite percent of initial price （Y） was considered as dependent variable and a power law equation was found to express the costs of both MF399 and MF285 tractors as a function of working time. Results showed that in CM method, average of economic life was 13 and 11 years for MF399 and MF285, respectively. It was also found that in BM method, economic life wasl0 and 8.5 years for MF399 and MF285, respectively.

Multivariate Analyses for Finding Significant Track Irregularities to Generate an Optimal Track Maintenance Schedule

We first discuss the relationship between the optimal track maintenance scheduling model and an efficient detection method for abnormal track irregularities given by the longitudinal level irregularity displacement (LLID). The results of applying the cluster analysis technique to the sampling data showed that maintenance operation is required for approximately 10% of the total lots, and these lots were further classified into three groups according to the degree of maintenance need. To analyze the background factors for detecting abnormal LLID lots, a principal component analysis was performed;the results showed that the first principal component represents LLIDs from the viewpoints of the rail structure, equipment, and operating conditions. Binomial and ordinal logit regression models (LRMs) were used to quantitatively investigate the determinants of abnormal LLIDs. Binomial LRM was used to characterize the abnormal LLIDs, whereas ordinal LRM was used to distinguish the degree of influence of factors that are considered to have a significant impact on LLIDs.

Overcoming Challenges in English for Aviation Maintenance: Technical Publications Selection for the Construction of a Corpus and Its Use to Teach Language Aspects Considering Learners Needs

Aviation English and Corpus Linguistics have been put together and focused by some investigations especially those regarding Aeronautical English (the language used between pilots and air traffic controllers in international radiotelephony communications). However, English used in aviation maintenance, specifically in written documents, has not been as much researched. This paper briefly explains the main concepts considering Aviation English and pre- sents—based on previous researches—aircraft maintenance professionals’ needs and regulatory agencies’ requirements related to language proficiency. Afterwards, it summarizes information about the most important technical publications for aircraft maintenance and describes the compilation of the Corpus of documents related to aviation maintenance (CoDoRAM). At the end, some ways the corpus can be used to teach vocabulary and grammar in English are pointed out. Although corpus compilation and analysis have been proved to be valuable for research and instructional purposes, most of publications encompass English for academic purposes teaching context. For that reason, this is a way to inspire new projects related to English used in aviation maintenance and the use of corpora in English for specific purposes classes.

Network-level optimization method for road network maintenance programming based on network efficiency

To maintain their capacity,transportation infrastructures are in need of regular maintenance and rehabilitation.The major challenge facing transportation engineers is the network-level policies to maintain the deteriorating roads at an acceptable level of serviceability.In this work,a quantitative transportation network efficiency measure is presented and then how to determine optimally network-level road maintenance policy depending on the road importance to the network performance has been demonstrated.The examples show that the different roads should be set different maintenance time points in terms of the retention capacities of the roads,because the different roads play different roles in network and have different important degrees to the network performance.This network-level road maintenance optimization method could not only save lots of infrastructure investments,but also ensure the service level of the existing transportation system.

Development of Optimal Maintenance Policies for Offshore Wind Turbine Gearboxes Based on the Non-homogeneous Continuous-Time Markov Process

Gearbox in offshore wind turbines is a component with the highest failure rates during operation. Analysis of gearbox repair policy that includes economic considerations is important for the effective operation of offshore wind farms. From their initial perfect working states, gearboxes degrade with time, which leads to decreased working efficiency. Thus, offshore wind turbine gearboxes can be considered to be multi-state systems with the various levels of productivity for different working states. To efficiently compute the time-dependent distribution of this multi-state system and analyze its reliability, application of the nonhomogeneous continuous-time Markov process(NHCTMP) is appropriate for this type of object. To determine the relationship between operation time and maintenance cost, many factors must be taken into account, including maintenance processes and vessel requirements. Finally, an optimal repair policy can be formulated based on this relationship.