Many years experience of the operation of high stress(>72%specified minimum yield strength,SMYS)gas pipelines and statistical analysis results of pipeline incidents showed that the operating pipelines at stress lev...Many years experience of the operation of high stress(>72%specified minimum yield strength,SMYS)gas pipelines and statistical analysis results of pipeline incidents showed that the operating pipelines at stress levels over 72%SMYS have not presented problems in USA and Canada,and design factor does not control incidents or the safety of pipelines.Enhancing pipeline safety management level is most important for decreasing incident rate.The application history of higher design factors in the U.S and Canada was reviewed.And the effect of higher factors to the critical flaw size,puncture resistance,change of reliability with time,risk level and the arrest toughness requirements of pipeline were analyzed here.The comparison of pipeline failure rates and risk levels between two design factors(0.72 and 0.8)has shown that a change in design factor from 0.72 to 0.8 would bring little effect on failure rates and risk levels.On the basis of the analysis result,the application feasibility of design factor of 0.8 in China was discussed and the related suggestions were proposed.When an operator wishes to apply design factor 0.8 to gas pipeline,the following process is recommended:stress level of line pipe hydro test should be up to 100%SMYS,reliability and risk assessment at the design feasibility or conceptual stage should be conducted,Charpy impact energy should meet the need of pipeline crack arrest;and establish and execute risk based integrity management plan.The technology of pipeline steel metallurgy,line pipe fabrication and pipeline construction,and line pipe quality control level in China achieved tremendous progresses,and line pipe product standards and property indexes have come up to international advanced level.Furthermore,pipeline safety management has improved greatly in China.Consequently,the research for the feasibility of application of design factor of 0.8 in China has fundamental basis.展开更多
Due to the non-standardization and complexity of the farmland environment,it is always a huge challenge for tractors to achieve fully autonomy(work at Self-driving mode)all the time in agricultural industry.Whereas,wh...Due to the non-standardization and complexity of the farmland environment,it is always a huge challenge for tractors to achieve fully autonomy(work at Self-driving mode)all the time in agricultural industry.Whereas,when tractors work in the Tele-driving(or Remote driving)mode,the operators are prone to fatigue because they need to concentrate for long periods of time.In response to these,a dual-mode control strategy was proposed to integrate the advantages of both approaches,i.e.,by combing Self-driving at most of the time with Tele-driving under special(complex and hazardous)conditions through switching control method.First,the state switcher was proposed,which is used for smooth switching the driving modes according to different working states of a tractor.Then,the state switching control law and the corresponding subsystem tracking controllers were designed.Finally,the effectiveness and superiority of the dualmode control method were evaluated via actual experimental testing of a tractor whose results show that the proposed control method can switch smoothly,stably,and efficiently between the two driving modes automatically.The average control accuracy has been improved by 20%and 15%respectively,compared to the conventional Tele-driving control and Self-driving control with low-precision navigation.In conclusion,the proposed dualmode control method can not only satisfy the operation in the complex and changeable farmland environment,but also free drivers from high-intensity and fatiguing work.This provides a perfect application solution and theoretical support for the intelligentization of unmanned farm agricultural machinery with high safety and reliability.展开更多
With the gradual development of smart power plants and large-scale centralized control,there is a need to exchange a large number of signals between different DCS systems and between DCS and PLC systems.Different cont...With the gradual development of smart power plants and large-scale centralized control,there is a need to exchange a large number of signals between different DCS systems and between DCS and PLC systems.Different control systems have different brands and cannot communicate directly via networks.Moreover,due to network security concerns,the main control of unit units and the auxiliary control system of the entire plant cannot communicate directly via networks either.The commonly adopted methods for signal exchange between control systems are hardwiring and 485 communications.Both have obvious drawbacks,where hardwiring requires a large number of channels and cable laying;485 configuration is difficult,not easy to maintain,and faults are hard to locate.This paper studies how to strike a balance between the two,using a minimal amount of hardwiring to transmit a large number of signals,which is safe,reliable,cost-effective,and can be maintained by any control personnel without network security risks.展开更多
Based on the basic content of advanced technology,safety and reliability, and economic reasonability and the definition of mine ventilation system, 16 assessment indexes of ventilation system are put forward from the ...Based on the basic content of advanced technology,safety and reliability, and economic reasonability and the definition of mine ventilation system, 16 assessment indexes of ventilation system are put forward from the point of 8 aspects such as mine ventilation power, ventilation network, ventilation equipments, ventilation quality, ventilation monitoring, capacity of preventing and fighting disaster, ventilation consumption of power, and the capacity of ventila- tion system. A new assessment index system is put forward and has a good effect after being applied in coal mines.展开更多
基金supported by China National Petroleum Corporation Application Fundamental Research Foundation(Grant No.07A40401)
文摘Many years experience of the operation of high stress(>72%specified minimum yield strength,SMYS)gas pipelines and statistical analysis results of pipeline incidents showed that the operating pipelines at stress levels over 72%SMYS have not presented problems in USA and Canada,and design factor does not control incidents or the safety of pipelines.Enhancing pipeline safety management level is most important for decreasing incident rate.The application history of higher design factors in the U.S and Canada was reviewed.And the effect of higher factors to the critical flaw size,puncture resistance,change of reliability with time,risk level and the arrest toughness requirements of pipeline were analyzed here.The comparison of pipeline failure rates and risk levels between two design factors(0.72 and 0.8)has shown that a change in design factor from 0.72 to 0.8 would bring little effect on failure rates and risk levels.On the basis of the analysis result,the application feasibility of design factor of 0.8 in China was discussed and the related suggestions were proposed.When an operator wishes to apply design factor 0.8 to gas pipeline,the following process is recommended:stress level of line pipe hydro test should be up to 100%SMYS,reliability and risk assessment at the design feasibility or conceptual stage should be conducted,Charpy impact energy should meet the need of pipeline crack arrest;and establish and execute risk based integrity management plan.The technology of pipeline steel metallurgy,line pipe fabrication and pipeline construction,and line pipe quality control level in China achieved tremendous progresses,and line pipe product standards and property indexes have come up to international advanced level.Furthermore,pipeline safety management has improved greatly in China.Consequently,the research for the feasibility of application of design factor of 0.8 in China has fundamental basis.
基金supported in part by the Independent Innovation Project of Agricultural Science and Technology of Jiangsu Province(CX(20)3068)Modern Agricultural Machinery Equipment and Technology Demonstration and Promotion Project of Jiangsu Province(NJ2021-37)+1 种基金National Foreign Experts Program of China(G2021145010L)Science and Technology Project of Suzhou City(SNG2020039)。
文摘Due to the non-standardization and complexity of the farmland environment,it is always a huge challenge for tractors to achieve fully autonomy(work at Self-driving mode)all the time in agricultural industry.Whereas,when tractors work in the Tele-driving(or Remote driving)mode,the operators are prone to fatigue because they need to concentrate for long periods of time.In response to these,a dual-mode control strategy was proposed to integrate the advantages of both approaches,i.e.,by combing Self-driving at most of the time with Tele-driving under special(complex and hazardous)conditions through switching control method.First,the state switcher was proposed,which is used for smooth switching the driving modes according to different working states of a tractor.Then,the state switching control law and the corresponding subsystem tracking controllers were designed.Finally,the effectiveness and superiority of the dualmode control method were evaluated via actual experimental testing of a tractor whose results show that the proposed control method can switch smoothly,stably,and efficiently between the two driving modes automatically.The average control accuracy has been improved by 20%and 15%respectively,compared to the conventional Tele-driving control and Self-driving control with low-precision navigation.In conclusion,the proposed dualmode control method can not only satisfy the operation in the complex and changeable farmland environment,but also free drivers from high-intensity and fatiguing work.This provides a perfect application solution and theoretical support for the intelligentization of unmanned farm agricultural machinery with high safety and reliability.
文摘With the gradual development of smart power plants and large-scale centralized control,there is a need to exchange a large number of signals between different DCS systems and between DCS and PLC systems.Different control systems have different brands and cannot communicate directly via networks.Moreover,due to network security concerns,the main control of unit units and the auxiliary control system of the entire plant cannot communicate directly via networks either.The commonly adopted methods for signal exchange between control systems are hardwiring and 485 communications.Both have obvious drawbacks,where hardwiring requires a large number of channels and cable laying;485 configuration is difficult,not easy to maintain,and faults are hard to locate.This paper studies how to strike a balance between the two,using a minimal amount of hardwiring to transmit a large number of signals,which is safe,reliable,cost-effective,and can be maintained by any control personnel without network security risks.
基金Project 0424220161 supported by Science and Technology Foundation of Education Bureau of Henan Province
文摘Based on the basic content of advanced technology,safety and reliability, and economic reasonability and the definition of mine ventilation system, 16 assessment indexes of ventilation system are put forward from the point of 8 aspects such as mine ventilation power, ventilation network, ventilation equipments, ventilation quality, ventilation monitoring, capacity of preventing and fighting disaster, ventilation consumption of power, and the capacity of ventila- tion system. A new assessment index system is put forward and has a good effect after being applied in coal mines.
