Recently,PT Huadian Bukit Asam Power (HBAP) was awarded the"Zero Accident Award"by the Ministry of Manpower of the Republic of Indonesia.This national-level award for safe production in Indonesia serves to t...Recently,PT Huadian Bukit Asam Power (HBAP) was awarded the"Zero Accident Award"by the Ministry of Manpower of the Republic of Indonesia.This national-level award for safe production in Indonesia serves to testify to the enterprise's achievements in safe and stable operations from June 1,2018,to December 31,2023.展开更多
The rapid development of digital education provides new opportunities and challenges for teaching model innovation.This study aims to explore the application of the BOPPPS(Bridge-in,Objective,Pre-assessment,Participat...The rapid development of digital education provides new opportunities and challenges for teaching model innovation.This study aims to explore the application of the BOPPPS(Bridge-in,Objective,Pre-assessment,Participatory learning,Post-assessment,Summary)teaching method in the development of a blended teaching model for the Operations Research course under the background of digital education.In response to the characteristics of the course and the needs of the student group,the teaching design is reconstructed with a student-centered approach,increasing practical teaching links,improving the assessment and evaluation system,and effectively implementing it in conjunction with digital educational technology.This teaching model has shown significant effectiveness in the context of digital education,providing valuable experience and insights for the innovation of the Operations Research course.展开更多
With the advent of Industry 4.0, smart construction sites have seen significant development in China. However, accidents involving digitized tower cranes continue to be a persistent issue. Among the contributing facto...With the advent of Industry 4.0, smart construction sites have seen significant development in China. However, accidents involving digitized tower cranes continue to be a persistent issue. Among the contributing factors, human unsafe behavior stands out as a primary cause for these incidents. This study aims to assess the human reliability of tower crane operations on smart construction sites. To proactively enhance safety measures, the research employs text mining techniques (TF-IDF-Truncated SVD-Complement NB) to identify patterns of human errors among tower crane operators. Building upon the SHEL model, the study categorizes behavioral factors affecting human reliability in the man-machine interface, leading to the establishment of the Performance Shaping Factors (PSFs) system. Furthermore, the research constructs an error impact indicator system for the intelligent construction site tower crane operator interface. Using the DEMATEL method, it analyzes the significance of various factors influencing human errors in tower crane operations. Additionally, the ISM-MICMAC method is applied to unveil the hierarchical relationships and driving-dependent connections among these influencing factors. The findings indicate that personal state, operating procedures, and physical environment directly impact human errors, while personal capability, technological environment, and one fundamental organizational management factor contribute indirectly. .展开更多
The inefficiency of the aviation industry and the persistent rise in aviation hazards have been linked to weather phenomena.As a result,researchers are looking for better solutions to the problem.The study examined th...The inefficiency of the aviation industry and the persistent rise in aviation hazards have been linked to weather phenomena.As a result,researchers are looking for better solutions to the problem.The study examined the impact of thunderstorms on flight operations at Murtala Mohammed International Airport,Lagos.The data on thunderstorms and flight operations were sourced from Nigerian Meteorological Agency(NiMet)and Nigerian Airspace Management Agency(NAMA)respectively.In order to meet the research target,descriptive statistics(mean,standard deviation,and charts)and inferential statistics(Pearson’s Product Moment Correlation(PPMC)and Regression)were used.The significance level for all inferential analyses was set at 5%(0.05).The study revealed that 77.4%of thunderstorms occurred during the rainy season(April-October)while 22.6%occurred during the dry season(November-March).It also revealed some fluctuating movements of a thunderstorm in the study area.According to the findings,thunderstorms occur most frequently at the airport in June and less frequently in January and December.The study also discovered that thunderstorms at the airport are positively and significantly related to flight delays and cancellations,while the association between flight diversions and thunderstorm occurrence is positive but statistically insignificant.Furthermore,flight delays,flight diversions,and flight cancellations interact positively among themselves.The regression result of the study revealed that a 1%increase in thunderstorm occurrence leads to a 19.4%increase in flight delay,a 7.1%increase in flight cancellation,and a 4.3%increase in flight diversion.As a result,the study presented various regression models that may be utilized to make predictions.The study proposes consistent thunderstorm observation at the airport and steady forecasts using the regression models,based on the findings.However,it further recommends that pilots,air traffic controllers,and meteorologists be trained and retrained so that they can provide better and more efficient services.展开更多
In this article, we define the arithmetic operations of generalized trapezoidal picture fuzzy numbers by vertex method which is assembled on a combination of the (α, γ, β)-cut concept and standard interval analysis...In this article, we define the arithmetic operations of generalized trapezoidal picture fuzzy numbers by vertex method which is assembled on a combination of the (α, γ, β)-cut concept and standard interval analysis. Various related properties are explored. Finally, some computations of picture fuzzy functions over generalized picture fuzzy variables are illustrated by using our proposed technique.展开更多
The study examined the nexus between operations improvement function (dimensioned by contingency planning, benchmarking and continuous improvement processes) and organisational adaptability of Petroleum tank farms in ...The study examined the nexus between operations improvement function (dimensioned by contingency planning, benchmarking and continuous improvement processes) and organisational adaptability of Petroleum tank farms in South-South, Nigeria. The contingency theory and the theory of routine dynamics underpinned the study, and positivism was the underlying philosophy. The study adopted the cross-sectional survey through the use of questionnaire. 820 middle and top-level managers constituted the elements of the population, and the Krejcie & Morgan’s formula was used to determine the sample size of 262 respondents. Structural Equation Modeling was deployed to test the hypotheses at a 0.05 significance level. The results showed that contingency planning;benchmarking and continuous improvement processes all have a significant positive relationship with organisational adaptability of Petroleum tank farms in South-South, Nigeria. The study concludes that Petroleum tank farms’ operations should focus on the adoption of contingency planning, benchmarking and continuous improvement processes to enhance organisational adaptability. Therefore, it is recommended that the management of Petroleum tank farms should put in place mechanisms to advance continuous improvement processes by allocating the necessary amount of resources, such as energy, time and money, in order to promote the continuous development of the continuous improvement systems. Furthermore, managers of Petroleum tank farms should make better the adoption of contingency planning, ensuring that there is as much necessary training and information for employees on how to act during a crises situation, in order to evaluate safety and prepare in advance for recovery from disasters.展开更多
Pipelines are widely used for transporting oil resources in the context of offshore oil exploitation.The pipeline stress-strength analysis is an important stage in related design and ensuing construction techniques.In...Pipelines are widely used for transporting oil resources in the context of offshore oil exploitation.The pipeline stress-strength analysis is an important stage in related design and ensuing construction techniques.In this study,assuming representative work environment parameters,pipeline lifting operations are investigated numerically.More specifically,a time-domain coupled dynamic analysis method is used to conduct a hydrodynamic analysis under different current velocities and wave heights.The results show that proper operation requires the lifting points are reasonably set in combination with the length of the pipeline and the position of the lifting device on the construction ship.The impact of waves on the pipeline is limited,however lifting operations under strong wind and waves should be avoided as far as possible.展开更多
As the sustainable exploitation of marine resources develops,dual-platform joint operation has caught increasing attention.Dual-platform joint operation requires smaller relative motion between the two sub-platforms,w...As the sustainable exploitation of marine resources develops,dual-platform joint operation has caught increasing attention.Dual-platform joint operation requires smaller relative motion between the two sub-platforms,which is normally difficult to be satisfied by the traditional mooring system.Therefore,a new hybrid mooring system is developed and studied in this article.To ensure safety during platform movements,both the number of anchor chains and the relative motion between the two sub-platforms are reduced in the new hybrid mooring system.By performing numerical simulations based on three-dimensional potential flow theory in AQWA and physical experiments,the performances of both the new hybrid and traditional mooring systems under two different wave conditions(i.e.,working wave and freak wave conditions) are systematically investigated.Regarding the new hybrid mooring system,the relative stability between the two sub-platforms of the new system is better,and the platforms can restore stability faster when affected by freak waves.展开更多
The study was aimed at determining the impacts of operating Manually Operated Hand Lever Knapsack Sprayers (MOHLKS) on physiological responses of the operators as dependent on anthropometric variations and sex. Twenty...The study was aimed at determining the impacts of operating Manually Operated Hand Lever Knapsack Sprayers (MOHLKS) on physiological responses of the operators as dependent on anthropometric variations and sex. Twenty eight subjects, (4 female, 24 male) Mean ± SD: Age 22.5 ± 1.92, 24.29 ± 2.2 years;Body Mass Index 24.6 ± 4.8, 21.7 ± 2.4 kg/m<sup>2</sup> were employed in the study. Selected anthropometric parameters of weight and height were used to determine body mass index (BMI), with these are arm-reach forward, elbow to fingertip, hand length and hand width were measured to establish human variations in diversity. Subjects undertook the operation at 5 replicates each, before and after which information about operators’ body pain locations and body physiological changes of heart rates were obtained. Measured parameters were used in the determination of expended energy (EE), physiological cost (PC), oxygen intake (VO<sub>2</sub>) and aerobic power (VO<sub>2</sub>max). Alongside with these were operational parameters of stroke, pace and time taken to get the operation done and environmental factors of temperature and relative humidity. The results revealed on the average that the BMI (24.61 ± 4.78 kg/m<sup>2</sup>) in female operators was higher, this corresponded to PC and VO<sub>2</sub>, while the VO<sub>2</sub>max (34.83 ± 3.30 ml/min/kg) in males is higher. More EE was obtained in female subjects (3.53 ± 3.76 kCal/min) as compared to male subjects (3.42 ± 7.48 kCal/min). The main effects plot of operational factors on EE displayed the stroke made by the subjects during spraying operation as parameter with largest effect on EE. Regression equation for EE and PCI is given as PCI = 1.97 + 25.2 EE, while the P-value at α = 0.05 is 0.000 and R<sup>2</sup> = 98.8%. Post operational body pain showed that 19 out of 28 subjects incurred at least one type of body pain, with shoulder pain as most frequent. The results of the study suggest that early incidence of fatigue may occur in female operators as compared to the males, and in addition, cumulative trauma at shoulder, back, and upper and lower arm may result over time. Hence, it is recommended that the tank volume should be reduced and the straps for the shoulders should be supported with additional cushion.展开更多
Manufacturing system, with high level of complexity and with a mix of semi-repetitive and repetitive products, to become productive, should seek the standardization of products and processes to obtain the optimization...Manufacturing system, with high level of complexity and with a mix of semi-repetitive and repetitive products, to become productive, should seek the standardization of products and processes to obtain the optimization of use of production resources. However, it is necessary to measure the productivity, so that the system of measurement and control of manufacturing processes are an element critical as to ensure greater visibility of the flow's restrictions, minimized when detected properly. In this case, the automation of factory's measurement process can effectively contribute to ensuring the effectiveness of the function control of a manufacturing system. It is important to consider that the automation of the system of measurement and control of manufacturing processes, of complex environment, is heavily dependent of IT tools applied directly in the interface computational between the operation systems and the corporate systems. This heavy reliance, if exploited technically properly, allows that automation of the system of measurement and control of production makes the access to time real of availability of manufacturing process's data, such as processing time and setup time that it can export to a specialist software in programming production, for example, feasible. In this paper, the automation of the system of measurement and control of production is approached, in order to identify the main possibilities of the design of an information system capable to integrate the flow of information in an environment internal on manufacturing organizations, with emphasis in the digital manufacturing paradigm.展开更多
Objective: To study the public health Emergency Operations Centers(EOCs)in the US, the European Union, the UK and Australia, and summarize the good practice for the improvement of National Health Emergency Response Co...Objective: To study the public health Emergency Operations Centers(EOCs)in the US, the European Union, the UK and Australia, and summarize the good practice for the improvement of National Health Emergency Response Command Center in Chinese National Health and Family Planning Commission. Methods: Literature review was conducted to explore the EOCs of selected countries. Results: The study focused on EOC function, organizational structure, human resources and information management. The selected EOCs had the basic EOC functions of coordinating and commanding as well as the public health related functions such as monitoring the situation, risk assessment, and epidemiological briefings. The organizational structures of the EOCs were standardized, scalable and flexible. Incident Command System was the widely applied organizational structure with a strong preference. The EOCs were managed by a unit of emergency management during routine time and surge staff were engaged upon emergencies. The selected EOCs had clear information management framework including information collection, assessment and dissemination. Conclusions: The performance of National Health Emergency Response Command Center can be improved by learning from the good practice of the selected EOCs, including setting clear functions, standardizing the organizational structure, enhancing the human resource capacity and strengthening information management.展开更多
Coal preparation is an integral part of the coal commodity supply chain. This stage of post-mining, pre-utilization beneficiation uses low-cost separation technologies to remove unwanted mineral matter and moisture wh...Coal preparation is an integral part of the coal commodity supply chain. This stage of post-mining, pre-utilization beneficiation uses low-cost separation technologies to remove unwanted mineral matter and moisture which hinder the value of the coal product. Coal preparation plants typically employ several parallel circuits of cleaning and dewatering operations, with each circuit designed to optimally treat a specific size range of coal. Recent innovations in coal preparation have increased the efficiency and capac- ity of individual unit operations while reinforcing the standard parallel cleaning approach. This article, which describes the historical influences and state-of-the-art design for the various coal preparation unit operations, is organized to distinguish between coarse/intermediate coal cleaning and fine/ultrafine coal cleaning. Size reduction, screening, classification, cleaning, dewatering, waste disposal unit operations are particularly highlighted, with a special focus on the LI.S. design philosophy. Notable differences between the U.S. and international operations are described as appropriate.展开更多
Production planning models generated by common modeling systems do not involve constraints for process operations, and a solution optimized by these models is called a quasi-optimal plan. The quasi-optimal plan cannot...Production planning models generated by common modeling systems do not involve constraints for process operations, and a solution optimized by these models is called a quasi-optimal plan. The quasi-optimal plan cannot be executed in practice some time for no corresponding operating conditions. In order to determine a practi- cally feasible optimal plan and corresponding operating conditions of fluidized catalytic cracking unit (FCCU), a novel close-loop integrated strategy, including determination of a quasi-optimal plan, search of operating conditions of FCCU and revision of the production planning model, was proposed in this article. In the strategy, a generalized genetic algorithm (GA) coupled with a sequential process simulator of FCCU was applied to search operating conditions implementing the quasi-optimal plan of FCCU and output the optimal individual in the GA search as a final genetic individual. When no corresponding operating conditions were found, the final genetic individual based correction (FGIC) method was presented to revise the production planning model, and then a new quasi-optimal production plan was determined. The above steps were repeated until a practically feasible optimal plan and corresponding operating conditions of FCCU were obtained. The close-loop integrated strategy was validated by two cases, and it was indicated that the strategy was efficient in determining a practically executed optimal plan and corresponding operating conditions of FCCU.展开更多
Objective With the rapid development of mobile power and electronic vehicles, the application of lithium is in the ascendant, and the contradiction between its supply and demand is prominent.
A new interval arithmetic method is proposed to solve interval functions with correlated intervals through which the overestimation problem existing in interval analysis could be significantly alleviated. The correlat...A new interval arithmetic method is proposed to solve interval functions with correlated intervals through which the overestimation problem existing in interval analysis could be significantly alleviated. The correlation between interval parameters is defined by the multidimensional parallelepiped model which is convenient to describe the correlative and independent interval variables in a unified framework. The original interval variables with correlation are transformed into the standard space without correlation,and then the relationship between the original variables and the standard interval variables is obtained. The expressions of four basic interval arithmetic operations, namely addition, subtraction, multiplication, and division, are given in the standard space. Finally, several numerical examples and a two-step bar are used to demonstrate the effectiveness of the proposed method.展开更多
The air traffic management system(ATM)has the task of ensuring safe,orderly and expeditious flow of air traffic.The ATM system architecture is very much dependent on the concept of operations(ConOps).Over the years th...The air traffic management system(ATM)has the task of ensuring safe,orderly and expeditious flow of air traffic.The ATM system architecture is very much dependent on the concept of operations(ConOps).Over the years the evolution in ConOps has resulted in changes in the ATM′s physical architecture,improving its physical infrastructure,increasing the levels of automation and making operational changes to improve air traffic flow,to cope with increasing demand for air travel.However,what is less clear is the impact of such changes in ConOps on the ATM′s functional architecture.This is vital for ensuring optimality in the implementation of the physical architecture components to support the ATM functions.This paper reviews the changes in the ConOps over the years,proposes a temporally invariant ATM functional model,and discusses some of the main key technologies expected to make significant improvements to the ATM system.展开更多
Objective: To investigate the current status of medical support in military operations other than war (MOOTW) in domestic and overseas. Methods: This paper mainly adopts the descriptive, comparative and induction rese...Objective: To investigate the current status of medical support in military operations other than war (MOOTW) in domestic and overseas. Methods: This paper mainly adopts the descriptive, comparative and induction research methods. The current status of medical support in MOOTW in China, America, Russia, Israel, Canada, had been studied through some official papers, and series of professional books by analysis the precise date in various kinds of emergency event. Results: The contrast shows that there is still a quite huge development in medical support in MOOTW, no matter in China, or in other countries. Conclusion: In order to strengthen the forces, besides building professional rescue teams, it is necessary to take a regular revise of plans, according to missions` needs.展开更多
When Aerodrome Obstacle Standards cannot be met as a result of urban or technical development, an aeronautical study can be carried out with the permission of EASA, in conjunction with ICAO, to prove how aircrafts can...When Aerodrome Obstacle Standards cannot be met as a result of urban or technical development, an aeronautical study can be carried out with the permission of EASA, in conjunction with ICAO, to prove how aircrafts can achieve an equivalent level of safety. However currently, no detailed guidance for this procedure exists. This paper proposes such a safety assessment methodology in order to value obstacle clearance violations around airports. This method has already been applied to a safety case at Frankfurt Airport where a tower elevating 4 km out of threshold 25R severely violates obstacle limitation surfaces. The model data refers to a take-off and landing performance model (TLPM) computing precisely aircraft trajectories for both standard and engine out conditions at ground proximity. The generated tracks are used to estimate collision risk incrementally considering EASA/FAA, EU-OPS & ICAO clearance criteria. Normal operations are assessed with a probabilistic analysis of empirical take-off/landing track data generating the local actual navigation performance (ANP) on site. The ANP shows integration to collision risk for an aircraft with any obstacle. The obstacle is tested for clearance within a “5-step-plan” against all performance requirements for landing climb and take-off climb. The methodology thereby delivers a comprehensive risk picture: The presented safety case for Frankfurt Airport showed an equivalent safety level despite the violation of standards. The collision risk during both normal and degraded performance operations was still found to be within ICAO Collision Risk Model (CRM) limits, requiring only limited risk mitigation measures. The presented work should complement ICAO Doc 9774 Appendix 3.展开更多
In recent years,marine pilotage accidents occurring on a worldwide basis as a result of human error have not been ceased to transpire,despite advances in technology and a significant set of international conventions,r...In recent years,marine pilotage accidents occurring on a worldwide basis as a result of human error have not been ceased to transpire,despite advances in technology and a significant set of international conventions,regulations,and recommendations to reduce them.This paper aims to investigate the effect of human factors on the safety of maritime pilotage operations.The human factors that affect the operators who are performing ships’berthing operations have also been examined in detail.In this study,in order to determine the causes of human-related errors occurred in maritime pilotage accidents,a comprehensive literature review is carried out,and a considerable number of real past case examples and an analysis of the maritime accident investigation reports regarding pilotage operations events that occurred between 1995 and 2015 have been reviewed.To validate the identified humanrelated risk factors(HCFs)and explore other contributory factors,survey questionnaires and semi-structured interviews with domain experts have been conducted.A structural hierarchy diagram for the identified risk factors(HCFs)has been developed and validated through experienced experts belonging to the maritime sector.A questionnaire for pair-wise comparison is carried out and analysed using the analytic hierarchy process(AHP)approach to evaluate the weight and rank the importance of the identified human causal factors.The findings of this study will benefit the maritime industry,by identifying a new database on causal factors that are contributing to the occurrence of maritime pilotage disasters.The database can be used as a stand-alone reference or help implement effective risk reduction strategies to reduce the human error,that might occur during pilotage operations.展开更多
Immediately following a spill at sea, released oil ranging from diesel to light crude and diluted bitumen, will initially weather through evaporation, resulting in an elevated concentration of light hydrocarbons in th...Immediately following a spill at sea, released oil ranging from diesel to light crude and diluted bitumen, will initially weather through evaporation, resulting in an elevated concentration of light hydrocarbons in the air. As part of oil spill response operations, first responders use hand-held devices to monitor airborne concent- rations when approaching a spill. The feasibility of using numerical modelling as an additional tool to assess potential flammability and plan response operations in the spill area was explored in this study. The Lower Explosive Limit (LEL) is defined as the minimum concentration of a gas in air, in this case a mixture of evaporated hydrocarbons, which can produce a flash fire in the presence of an ignition source. This ignition source could be triggered by the vessel itself or by spill response operations. A framework was put into place, utilizing a three- dimensional hydrodynamic model (H3D), an oil spill model (SPILLCALC), and an air dispersion model (CALPUFF) to assess the risk of possible ignition of the hydrocarbon vapour in the event of a spill. The study looked at a hypothetical credible worst case tanker spill (16 500 m3) of diluted bitumen (cold lake winter blend) occurring at Arachne Reef in Haro Strait, British Columbia, Canada. SPILLCALC provided one-minute averaged vapour fluxes from the water surface for each of 17 modelled pseudo-components which were used as inputs to CALPUFF. Using the predicted airborne concentrations of each pseudo-component, time-scaled to one-second averages, the flammability potential in the immediate spill area was determined at each grid point using Le Chatelier’s mixing equation. The approach describe here was developed as a proof of concept, and could be established as a real-time system, bringing valuable information in addition to hand-held devices during a spill response, or during a response exercise. This modelling study was conducted as part of Kinder Morgan’s Trans Mountain Pipeline Expansion Project. There are a number of commercially available oil spill models but few if any are equipped with the ability to model air dispersion and forecast hazardous conditions as discussed in this paper.展开更多
文摘Recently,PT Huadian Bukit Asam Power (HBAP) was awarded the"Zero Accident Award"by the Ministry of Manpower of the Republic of Indonesia.This national-level award for safe production in Indonesia serves to testify to the enterprise's achievements in safe and stable operations from June 1,2018,to December 31,2023.
文摘The rapid development of digital education provides new opportunities and challenges for teaching model innovation.This study aims to explore the application of the BOPPPS(Bridge-in,Objective,Pre-assessment,Participatory learning,Post-assessment,Summary)teaching method in the development of a blended teaching model for the Operations Research course under the background of digital education.In response to the characteristics of the course and the needs of the student group,the teaching design is reconstructed with a student-centered approach,increasing practical teaching links,improving the assessment and evaluation system,and effectively implementing it in conjunction with digital educational technology.This teaching model has shown significant effectiveness in the context of digital education,providing valuable experience and insights for the innovation of the Operations Research course.
文摘With the advent of Industry 4.0, smart construction sites have seen significant development in China. However, accidents involving digitized tower cranes continue to be a persistent issue. Among the contributing factors, human unsafe behavior stands out as a primary cause for these incidents. This study aims to assess the human reliability of tower crane operations on smart construction sites. To proactively enhance safety measures, the research employs text mining techniques (TF-IDF-Truncated SVD-Complement NB) to identify patterns of human errors among tower crane operators. Building upon the SHEL model, the study categorizes behavioral factors affecting human reliability in the man-machine interface, leading to the establishment of the Performance Shaping Factors (PSFs) system. Furthermore, the research constructs an error impact indicator system for the intelligent construction site tower crane operator interface. Using the DEMATEL method, it analyzes the significance of various factors influencing human errors in tower crane operations. Additionally, the ISM-MICMAC method is applied to unveil the hierarchical relationships and driving-dependent connections among these influencing factors. The findings indicate that personal state, operating procedures, and physical environment directly impact human errors, while personal capability, technological environment, and one fundamental organizational management factor contribute indirectly. .
文摘The inefficiency of the aviation industry and the persistent rise in aviation hazards have been linked to weather phenomena.As a result,researchers are looking for better solutions to the problem.The study examined the impact of thunderstorms on flight operations at Murtala Mohammed International Airport,Lagos.The data on thunderstorms and flight operations were sourced from Nigerian Meteorological Agency(NiMet)and Nigerian Airspace Management Agency(NAMA)respectively.In order to meet the research target,descriptive statistics(mean,standard deviation,and charts)and inferential statistics(Pearson’s Product Moment Correlation(PPMC)and Regression)were used.The significance level for all inferential analyses was set at 5%(0.05).The study revealed that 77.4%of thunderstorms occurred during the rainy season(April-October)while 22.6%occurred during the dry season(November-March).It also revealed some fluctuating movements of a thunderstorm in the study area.According to the findings,thunderstorms occur most frequently at the airport in June and less frequently in January and December.The study also discovered that thunderstorms at the airport are positively and significantly related to flight delays and cancellations,while the association between flight diversions and thunderstorm occurrence is positive but statistically insignificant.Furthermore,flight delays,flight diversions,and flight cancellations interact positively among themselves.The regression result of the study revealed that a 1%increase in thunderstorm occurrence leads to a 19.4%increase in flight delay,a 7.1%increase in flight cancellation,and a 4.3%increase in flight diversion.As a result,the study presented various regression models that may be utilized to make predictions.The study proposes consistent thunderstorm observation at the airport and steady forecasts using the regression models,based on the findings.However,it further recommends that pilots,air traffic controllers,and meteorologists be trained and retrained so that they can provide better and more efficient services.
文摘In this article, we define the arithmetic operations of generalized trapezoidal picture fuzzy numbers by vertex method which is assembled on a combination of the (α, γ, β)-cut concept and standard interval analysis. Various related properties are explored. Finally, some computations of picture fuzzy functions over generalized picture fuzzy variables are illustrated by using our proposed technique.
文摘The study examined the nexus between operations improvement function (dimensioned by contingency planning, benchmarking and continuous improvement processes) and organisational adaptability of Petroleum tank farms in South-South, Nigeria. The contingency theory and the theory of routine dynamics underpinned the study, and positivism was the underlying philosophy. The study adopted the cross-sectional survey through the use of questionnaire. 820 middle and top-level managers constituted the elements of the population, and the Krejcie & Morgan’s formula was used to determine the sample size of 262 respondents. Structural Equation Modeling was deployed to test the hypotheses at a 0.05 significance level. The results showed that contingency planning;benchmarking and continuous improvement processes all have a significant positive relationship with organisational adaptability of Petroleum tank farms in South-South, Nigeria. The study concludes that Petroleum tank farms’ operations should focus on the adoption of contingency planning, benchmarking and continuous improvement processes to enhance organisational adaptability. Therefore, it is recommended that the management of Petroleum tank farms should put in place mechanisms to advance continuous improvement processes by allocating the necessary amount of resources, such as energy, time and money, in order to promote the continuous development of the continuous improvement systems. Furthermore, managers of Petroleum tank farms should make better the adoption of contingency planning, ensuring that there is as much necessary training and information for employees on how to act during a crises situation, in order to evaluate safety and prepare in advance for recovery from disasters.
基金This study was financially supported by the Program for Scientific Research Start-Up Funds of Guangdong Ocean University(060302072101)Comparative Study,and Optimization of Horizontal Lifting of Subsea Pipeline(2021E05011).
文摘Pipelines are widely used for transporting oil resources in the context of offshore oil exploitation.The pipeline stress-strength analysis is an important stage in related design and ensuing construction techniques.In this study,assuming representative work environment parameters,pipeline lifting operations are investigated numerically.More specifically,a time-domain coupled dynamic analysis method is used to conduct a hydrodynamic analysis under different current velocities and wave heights.The results show that proper operation requires the lifting points are reasonably set in combination with the length of the pipeline and the position of the lifting device on the construction ship.The impact of waves on the pipeline is limited,however lifting operations under strong wind and waves should be avoided as far as possible.
基金financially supported by the National Natural Science Foundation of China (Grant No. 52071161)。
文摘As the sustainable exploitation of marine resources develops,dual-platform joint operation has caught increasing attention.Dual-platform joint operation requires smaller relative motion between the two sub-platforms,which is normally difficult to be satisfied by the traditional mooring system.Therefore,a new hybrid mooring system is developed and studied in this article.To ensure safety during platform movements,both the number of anchor chains and the relative motion between the two sub-platforms are reduced in the new hybrid mooring system.By performing numerical simulations based on three-dimensional potential flow theory in AQWA and physical experiments,the performances of both the new hybrid and traditional mooring systems under two different wave conditions(i.e.,working wave and freak wave conditions) are systematically investigated.Regarding the new hybrid mooring system,the relative stability between the two sub-platforms of the new system is better,and the platforms can restore stability faster when affected by freak waves.
文摘The study was aimed at determining the impacts of operating Manually Operated Hand Lever Knapsack Sprayers (MOHLKS) on physiological responses of the operators as dependent on anthropometric variations and sex. Twenty eight subjects, (4 female, 24 male) Mean ± SD: Age 22.5 ± 1.92, 24.29 ± 2.2 years;Body Mass Index 24.6 ± 4.8, 21.7 ± 2.4 kg/m<sup>2</sup> were employed in the study. Selected anthropometric parameters of weight and height were used to determine body mass index (BMI), with these are arm-reach forward, elbow to fingertip, hand length and hand width were measured to establish human variations in diversity. Subjects undertook the operation at 5 replicates each, before and after which information about operators’ body pain locations and body physiological changes of heart rates were obtained. Measured parameters were used in the determination of expended energy (EE), physiological cost (PC), oxygen intake (VO<sub>2</sub>) and aerobic power (VO<sub>2</sub>max). Alongside with these were operational parameters of stroke, pace and time taken to get the operation done and environmental factors of temperature and relative humidity. The results revealed on the average that the BMI (24.61 ± 4.78 kg/m<sup>2</sup>) in female operators was higher, this corresponded to PC and VO<sub>2</sub>, while the VO<sub>2</sub>max (34.83 ± 3.30 ml/min/kg) in males is higher. More EE was obtained in female subjects (3.53 ± 3.76 kCal/min) as compared to male subjects (3.42 ± 7.48 kCal/min). The main effects plot of operational factors on EE displayed the stroke made by the subjects during spraying operation as parameter with largest effect on EE. Regression equation for EE and PCI is given as PCI = 1.97 + 25.2 EE, while the P-value at α = 0.05 is 0.000 and R<sup>2</sup> = 98.8%. Post operational body pain showed that 19 out of 28 subjects incurred at least one type of body pain, with shoulder pain as most frequent. The results of the study suggest that early incidence of fatigue may occur in female operators as compared to the males, and in addition, cumulative trauma at shoulder, back, and upper and lower arm may result over time. Hence, it is recommended that the tank volume should be reduced and the straps for the shoulders should be supported with additional cushion.
文摘Manufacturing system, with high level of complexity and with a mix of semi-repetitive and repetitive products, to become productive, should seek the standardization of products and processes to obtain the optimization of use of production resources. However, it is necessary to measure the productivity, so that the system of measurement and control of manufacturing processes are an element critical as to ensure greater visibility of the flow's restrictions, minimized when detected properly. In this case, the automation of factory's measurement process can effectively contribute to ensuring the effectiveness of the function control of a manufacturing system. It is important to consider that the automation of the system of measurement and control of manufacturing processes, of complex environment, is heavily dependent of IT tools applied directly in the interface computational between the operation systems and the corporate systems. This heavy reliance, if exploited technically properly, allows that automation of the system of measurement and control of production makes the access to time real of availability of manufacturing process's data, such as processing time and setup time that it can export to a specialist software in programming production, for example, feasible. In this paper, the automation of the system of measurement and control of production is approached, in order to identify the main possibilities of the design of an information system capable to integrate the flow of information in an environment internal on manufacturing organizations, with emphasis in the digital manufacturing paradigm.
文摘Objective: To study the public health Emergency Operations Centers(EOCs)in the US, the European Union, the UK and Australia, and summarize the good practice for the improvement of National Health Emergency Response Command Center in Chinese National Health and Family Planning Commission. Methods: Literature review was conducted to explore the EOCs of selected countries. Results: The study focused on EOC function, organizational structure, human resources and information management. The selected EOCs had the basic EOC functions of coordinating and commanding as well as the public health related functions such as monitoring the situation, risk assessment, and epidemiological briefings. The organizational structures of the EOCs were standardized, scalable and flexible. Incident Command System was the widely applied organizational structure with a strong preference. The EOCs were managed by a unit of emergency management during routine time and surge staff were engaged upon emergencies. The selected EOCs had clear information management framework including information collection, assessment and dissemination. Conclusions: The performance of National Health Emergency Response Command Center can be improved by learning from the good practice of the selected EOCs, including setting clear functions, standardizing the organizational structure, enhancing the human resource capacity and strengthening information management.
文摘Coal preparation is an integral part of the coal commodity supply chain. This stage of post-mining, pre-utilization beneficiation uses low-cost separation technologies to remove unwanted mineral matter and moisture which hinder the value of the coal product. Coal preparation plants typically employ several parallel circuits of cleaning and dewatering operations, with each circuit designed to optimally treat a specific size range of coal. Recent innovations in coal preparation have increased the efficiency and capac- ity of individual unit operations while reinforcing the standard parallel cleaning approach. This article, which describes the historical influences and state-of-the-art design for the various coal preparation unit operations, is organized to distinguish between coarse/intermediate coal cleaning and fine/ultrafine coal cleaning. Size reduction, screening, classification, cleaning, dewatering, waste disposal unit operations are particularly highlighted, with a special focus on the LI.S. design philosophy. Notable differences between the U.S. and international operations are described as appropriate.
文摘Production planning models generated by common modeling systems do not involve constraints for process operations, and a solution optimized by these models is called a quasi-optimal plan. The quasi-optimal plan cannot be executed in practice some time for no corresponding operating conditions. In order to determine a practi- cally feasible optimal plan and corresponding operating conditions of fluidized catalytic cracking unit (FCCU), a novel close-loop integrated strategy, including determination of a quasi-optimal plan, search of operating conditions of FCCU and revision of the production planning model, was proposed in this article. In the strategy, a generalized genetic algorithm (GA) coupled with a sequential process simulator of FCCU was applied to search operating conditions implementing the quasi-optimal plan of FCCU and output the optimal individual in the GA search as a final genetic individual. When no corresponding operating conditions were found, the final genetic individual based correction (FGIC) method was presented to revise the production planning model, and then a new quasi-optimal production plan was determined. The above steps were repeated until a practically feasible optimal plan and corresponding operating conditions of FCCU were obtained. The close-loop integrated strategy was validated by two cases, and it was indicated that the strategy was efficient in determining a practically executed optimal plan and corresponding operating conditions of FCCU.
基金financially supported by China Geological Survey(grant No.12120113057300)the National Natural Science Foundation of China(grant No.41502082)
文摘Objective With the rapid development of mobile power and electronic vehicles, the application of lithium is in the ascendant, and the contradiction between its supply and demand is prominent.
基金supported by the National Natural Science Foundation for Excellent Young Scholars(Grant 51222502)the National Natural Science Foundation of China(Grant 11172096)the Funds for State Key Laboratory of Construction Machinery(SKLCM2014-1)
文摘A new interval arithmetic method is proposed to solve interval functions with correlated intervals through which the overestimation problem existing in interval analysis could be significantly alleviated. The correlation between interval parameters is defined by the multidimensional parallelepiped model which is convenient to describe the correlative and independent interval variables in a unified framework. The original interval variables with correlation are transformed into the standard space without correlation,and then the relationship between the original variables and the standard interval variables is obtained. The expressions of four basic interval arithmetic operations, namely addition, subtraction, multiplication, and division, are given in the standard space. Finally, several numerical examples and a two-step bar are used to demonstrate the effectiveness of the proposed method.
文摘The air traffic management system(ATM)has the task of ensuring safe,orderly and expeditious flow of air traffic.The ATM system architecture is very much dependent on the concept of operations(ConOps).Over the years the evolution in ConOps has resulted in changes in the ATM′s physical architecture,improving its physical infrastructure,increasing the levels of automation and making operational changes to improve air traffic flow,to cope with increasing demand for air travel.However,what is less clear is the impact of such changes in ConOps on the ATM′s functional architecture.This is vital for ensuring optimality in the implementation of the physical architecture components to support the ATM functions.This paper reviews the changes in the ConOps over the years,proposes a temporally invariant ATM functional model,and discusses some of the main key technologies expected to make significant improvements to the ATM system.
文摘Objective: To investigate the current status of medical support in military operations other than war (MOOTW) in domestic and overseas. Methods: This paper mainly adopts the descriptive, comparative and induction research methods. The current status of medical support in MOOTW in China, America, Russia, Israel, Canada, had been studied through some official papers, and series of professional books by analysis the precise date in various kinds of emergency event. Results: The contrast shows that there is still a quite huge development in medical support in MOOTW, no matter in China, or in other countries. Conclusion: In order to strengthen the forces, besides building professional rescue teams, it is necessary to take a regular revise of plans, according to missions` needs.
文摘When Aerodrome Obstacle Standards cannot be met as a result of urban or technical development, an aeronautical study can be carried out with the permission of EASA, in conjunction with ICAO, to prove how aircrafts can achieve an equivalent level of safety. However currently, no detailed guidance for this procedure exists. This paper proposes such a safety assessment methodology in order to value obstacle clearance violations around airports. This method has already been applied to a safety case at Frankfurt Airport where a tower elevating 4 km out of threshold 25R severely violates obstacle limitation surfaces. The model data refers to a take-off and landing performance model (TLPM) computing precisely aircraft trajectories for both standard and engine out conditions at ground proximity. The generated tracks are used to estimate collision risk incrementally considering EASA/FAA, EU-OPS & ICAO clearance criteria. Normal operations are assessed with a probabilistic analysis of empirical take-off/landing track data generating the local actual navigation performance (ANP) on site. The ANP shows integration to collision risk for an aircraft with any obstacle. The obstacle is tested for clearance within a “5-step-plan” against all performance requirements for landing climb and take-off climb. The methodology thereby delivers a comprehensive risk picture: The presented safety case for Frankfurt Airport showed an equivalent safety level despite the violation of standards. The collision risk during both normal and degraded performance operations was still found to be within ICAO Collision Risk Model (CRM) limits, requiring only limited risk mitigation measures. The presented work should complement ICAO Doc 9774 Appendix 3.
文摘In recent years,marine pilotage accidents occurring on a worldwide basis as a result of human error have not been ceased to transpire,despite advances in technology and a significant set of international conventions,regulations,and recommendations to reduce them.This paper aims to investigate the effect of human factors on the safety of maritime pilotage operations.The human factors that affect the operators who are performing ships’berthing operations have also been examined in detail.In this study,in order to determine the causes of human-related errors occurred in maritime pilotage accidents,a comprehensive literature review is carried out,and a considerable number of real past case examples and an analysis of the maritime accident investigation reports regarding pilotage operations events that occurred between 1995 and 2015 have been reviewed.To validate the identified humanrelated risk factors(HCFs)and explore other contributory factors,survey questionnaires and semi-structured interviews with domain experts have been conducted.A structural hierarchy diagram for the identified risk factors(HCFs)has been developed and validated through experienced experts belonging to the maritime sector.A questionnaire for pair-wise comparison is carried out and analysed using the analytic hierarchy process(AHP)approach to evaluate the weight and rank the importance of the identified human causal factors.The findings of this study will benefit the maritime industry,by identifying a new database on causal factors that are contributing to the occurrence of maritime pilotage disasters.The database can be used as a stand-alone reference or help implement effective risk reduction strategies to reduce the human error,that might occur during pilotage operations.
文摘Immediately following a spill at sea, released oil ranging from diesel to light crude and diluted bitumen, will initially weather through evaporation, resulting in an elevated concentration of light hydrocarbons in the air. As part of oil spill response operations, first responders use hand-held devices to monitor airborne concent- rations when approaching a spill. The feasibility of using numerical modelling as an additional tool to assess potential flammability and plan response operations in the spill area was explored in this study. The Lower Explosive Limit (LEL) is defined as the minimum concentration of a gas in air, in this case a mixture of evaporated hydrocarbons, which can produce a flash fire in the presence of an ignition source. This ignition source could be triggered by the vessel itself or by spill response operations. A framework was put into place, utilizing a three- dimensional hydrodynamic model (H3D), an oil spill model (SPILLCALC), and an air dispersion model (CALPUFF) to assess the risk of possible ignition of the hydrocarbon vapour in the event of a spill. The study looked at a hypothetical credible worst case tanker spill (16 500 m3) of diluted bitumen (cold lake winter blend) occurring at Arachne Reef in Haro Strait, British Columbia, Canada. SPILLCALC provided one-minute averaged vapour fluxes from the water surface for each of 17 modelled pseudo-components which were used as inputs to CALPUFF. Using the predicted airborne concentrations of each pseudo-component, time-scaled to one-second averages, the flammability potential in the immediate spill area was determined at each grid point using Le Chatelier’s mixing equation. The approach describe here was developed as a proof of concept, and could be established as a real-time system, bringing valuable information in addition to hand-held devices during a spill response, or during a response exercise. This modelling study was conducted as part of Kinder Morgan’s Trans Mountain Pipeline Expansion Project. There are a number of commercially available oil spill models but few if any are equipped with the ability to model air dispersion and forecast hazardous conditions as discussed in this paper.