The end-Triassic （also Triassic-Jurassic） mass extinction severely affected life on planet Earth 200 million years ago. Paleoclimate change triggered by the volcanic eruptions of the Central Atlantic Magmatic Provin...The end-Triassic （also Triassic-Jurassic） mass extinction severely affected life on planet Earth 200 million years ago. Paleoclimate change triggered by the volcanic eruptions of the Central Atlantic Magmatic Province （CAMP） caused a great loss of marine biodiversity, among which 96% coral genera were get lost. However, there is precious little detail on the paleoecology and growth forms lost between the latest Triassic extinction and the Early Jurassic recovery. Here a new pilot study was conducted by analyzing corallite integration levels among corals from the latest Triassic and Early Jurassic times. Integration levels in corals from the Late Triassic and Early Jurassic were determined through both the Paleobiology Database as well as from a comprehensive museum collection of fossil corals. Results suggest that in addition to a major loss of diversity following the end-Triassic mass extinction, there also was a significant loss of highly integrated corals as clearly evidenced by the coral data from the Early Jurassic. This confirms our hypothesis of paleoecological selectivity for corals following the end-Triassic mass extinction. This study highlights the importance of assigning sim- ple to advanced paleoecological characters with integration levels, which opens a useful approach to understanding of mass extinction and the dynamics of the recovery.展开更多
Understanding the urban-rural development mechanism is critical for implementing rural revival and new-type urbanization.However,it remains a challenge to quantify the urban-rural integrated development level(URIDL)an...Understanding the urban-rural development mechanism is critical for implementing rural revival and new-type urbanization.However,it remains a challenge to quantify the urban-rural integrated development level(URIDL)and its impact factors.Hence,we constructed an assessment system for the URIDL from spatial,economic,social,life,and ecological integration.The spatial autocorrelation and Spearman rank correlation coefficients were used to assess the spatiotemporal variation of the URIDL and the trade-off synergistic relationship among the subsystems at the provincial scale in China using socio-economic statistical data from 2000 to 2020.A spatial panel quantile regression model was used to analyze the driving mechanism.The results showed that the URIDL of China increased by 0.19%from 2000 to 2020,and a high-high(H-H)spatial agglomeration pattern occurred in the Yangtze River Delta and the Beijing-Tianjin-Hebei regions.Spatial integration significantly contributed to the other subsystems,whereas economic integration had a significant negative impact on the other subsystems in the eastern coastal and southwestern regions.Per capita Gross Domestic Product(GDP)improved the URIDL,whereas other factors,such as fiscal revenue decentralization,had inhibiting effects.Notably,the impact of factors on URIDL varies across different quantiles.Finally,we proposed policy recommendations for differentiated improvement of URIDL based on its evolution and regional development level during the research period.展开更多
The rapid advancement of the thin-film lithium niobate(LiNbO_(3))platform has established it as a premier choice for high-performance photonics integrated circuits.However,the scalability and cost-efficiency of this p...The rapid advancement of the thin-film lithium niobate(LiNbO_(3))platform has established it as a premier choice for high-performance photonics integrated circuits.However,the scalability and cost-efficiency of this platform are hindered by the reliance on chip-level fabrication and integration for passive and active components,necessitating a robust wafer-level LiNbO_(3)heterogeneous integration platform.Despite its critical role in enabling ultrahigh-speed optical interconnects,as well as optical mmWave/THz sensing and communication,the realization of ultrahigh-speed photodiodes and optical coherent receivers on the LiNbO_(3)platform remains an unresolved challenge.This is primarily due to the challenges associated with the large-scale integration of direct-bandgap materials.To address these challenges,we have developed a scalable,high-speed InP-LiNbO_(3)wafer-level heterogeneous integration platform.This platform facilitates the fabrication of ultrahigh-speed photodiodes with a bandwidth of 140 GHz,capable of receiving high-quality 100-Gbaud pulse amplitude modulation(PAM4)signals.Moreover,we demonstrate a sevenchannel,single-polarization I–Q coherent receiver chip with an aggregate receiving capacity of 3.584 Tbit s^(-1).This coherent receiver exhibits a balanced detection bandwidth of 60 GHz and a common mode rejection ratio(CMRR)exceeding 20 dB.It achieves receiving capacities of 600 Gbit s^(-1)λ^(-1)with a 100-Gbaud 64-QAM signal and 512 Gbit s^(-1)λ^(-1)with a 128-Gbaud 16-QAM signal.Furthermore,energy consumption as low as 9.6 fJ bit^(-1) and 13.5 fJ bit^(-1) is achieved for 200 Gbit s^(-1)and 400 Gbit s^(-1)capacities,respectively.Our work provides a viable pathway toward enabling Pbps hyperscale data center interconnects,as well as optical mmWave/THz sensing and communication.展开更多
Antenna Group Delay Variation(AGDV)is a hardware error source that affects the performance of Dual-Frequency Multi-Constellation(DFMC)Ground-based Augmentation System(GBAS),and these errors are difficult to distinguis...Antenna Group Delay Variation(AGDV)is a hardware error source that affects the performance of Dual-Frequency Multi-Constellation(DFMC)Ground-based Augmentation System(GBAS),and these errors are difficult to distinguish from multipath errors.Currently,AGDV is usually modeled as a part of the multipath error,which is called the multipath-AGDV model.However,because of the inconsistency of AGDV and multipath when switching among different positioning modes of GBAS,and because the traditional model does not consider the impact of the azimuth on AGDV,using the traditional multipath-AGDV model will cause the protection levels to be inaccurately calculated.In this paper,azimuth-based modeling of AGDV is conducted by using anechoic chamber measurements.The biases and standard deviations of AGDV based on azimuths are analyzed and modeled,and the calculation method for the DFMC GBAS protection level is optimized.The results show that the azimuth-based AGDV model and protection level optimization algorithm can better avoid the error exceeding the protection level than the multipath-AGDV model.Compared with AGDV elevation model,the VPLs of the B1C signal are increased by 0.24 m and 0.06 m,and the VPLs of the B2a signal are reduced by 0.01 m and 0.16 m using the 100 s and 600 s DFree filtering positioning modes,respectively.The changes in the B1C and B2a protection levels reflect the changes in AGDV corresponding to the azimuth for the respective frequencies,further ensuring the integrity of airborne users,especially when they turn near the airport.展开更多
An integration-centric approach is proposed to handle inadequate information in the system readiness level （SRL） assessment using the evidential reasoning （ER） algorithm. Current SRL assessment approaches cannot b...An integration-centric approach is proposed to handle inadequate information in the system readiness level （SRL） assessment using the evidential reasoning （ER） algorithm. Current SRL assessment approaches cannot be applied to handle inadequate information as the input. The ER-based approach is proposed to synthesize inadequate input information and an integration-centric perspective is applied to reduce the computational complexity. Two case studies are performed to validate the efficiency of the proposed approach. And these studies are also performed to study how the inadequate information will affect the assessment result. And the differences caused by the system＇s structure. The importance of the system＇s structure in the SRL assessment is demonstrated and the contributions made in this study are summarized as conclusions.展开更多
Proton therapy is the most advanced radiotherapy approach in the world,and causes less damage to normal human tissue than traditional radiotherapy.Because the treatment process produces a high-energy proton beam,the p...Proton therapy is the most advanced radiotherapy approach in the world,and causes less damage to normal human tissue than traditional radiotherapy.Because the treatment process produces a high-energy proton beam,the personnel safety interlock system mainly considers measures to protect personnel from radiation hazards during beam preparation and the beam release process.Unlike other safety interlock systems,the personnel safety interlock system designed in this study focuses on the safety and stability of the system itself.The hardware and software of important interlock control loops are designed and developed according to the requirements of Safety Integrity Level 3 specified by IEC61508.A set of redundant ring networks was developed to ensure that damage to a certain network line does not affect the normal operation of the system.A set of friendly operation interfaces and data storage systems were developed to ensure that the operator can monitor the data in real time and trace the data.The personnel safety interlock system mainly includes a beam enabling function,clearance function,and emergency stop function.The system was put into actual use and successfully ensured personnel safety.展开更多
In this study,a novel safety integrity level(SIL)determination methodology of safety instrumented systems(SISs)with parameter uncertainty is proposed by combining multistage dynamic Bayesian networks(DBNs)and Monte Ca...In this study,a novel safety integrity level(SIL)determination methodology of safety instrumented systems(SISs)with parameter uncertainty is proposed by combining multistage dynamic Bayesian networks(DBNs)and Monte Carlo simulation.A multistage DBN model for SIL determination with multiple redundant cells is established.The models of function inspection test interval and function inspection test stages are alternately connected to form the multistage DBNs.The redundant cells can have different M out of N voting system architectures.An automatic modeling of conditional probability between nodes is developed.The SIL determination of SISs with parameter uncertainty is constructed by using the multistage DBNs and Monte Carlo simulation.A high-pressure SIS in the export of oil wellplatform is adopted to demonstrate the application of the proposed approach.The SIL and availability of the SIS and its subsystems are obtained.The influence of single subsystem on the SIL and availability of the SIS is studied.The influence of single redundant element on the SIL and availability of the subsystem is analyzed.A user-friendly SIL determination software with parameter uncertainty is developed on MATLAB graphical user interface.展开更多
Worldwide Interoperability for Microwave Access(WiMAX)trusts Multiple Input Multiple Output-Orthogonal Frequency Division Multiplexing(MIMO-OFDM)combination for the deployment of physical layer functions and for conne...Worldwide Interoperability for Microwave Access(WiMAX)trusts Multiple Input Multiple Output-Orthogonal Frequency Division Multiplexing(MIMO-OFDM)combination for the deployment of physical layer functions and for connecting the medium access control to the wireless media.Even though Orthogonal Frequency Division Multiplexing(OFDM)facilitates reliable digital broadband transmission in the fading wireless channels,the presence of synchro-nization errors in the form of Carrier Frequency Offset(CFO)and Time Offset(TO)adversely affect the performance of OFDM based physical layers.The objective of this work is to improve the accuracy of the frequency and the time offset estimation in the WiMAX physical layer.A method to enhance the synchro-nization accuracy byfine-tuning the merit factor of the preamble sequence is sug-gested in this paper.Also,a new preamble with improved synchronization accuracy is proposed for the WiMAX system.The performance of the proposed preamble is evaluated in a Rayleigh fading channel and the results of simulations show that the Mean Square Error(MSE)in offset estimation is significantly reduced and it outperforms the standard WiMAX preamble.展开更多
Contemporary system maturity assessment approaches have failed to provide robust quantitative system evaluations resulting in increased program costs and developmental risks.Standard assessment metrics,such as Technol...Contemporary system maturity assessment approaches have failed to provide robust quantitative system evaluations resulting in increased program costs and developmental risks.Standard assessment metrics,such as Technology Readiness Levels（TRL）,do not sufficiently evaluate increasingly complex systems.The System Readiness Level（SRL）is a newly developed system development metric that is a mathematical function of TRL and Integration Readiness Level（IRL） values for the components and connections of a particular system.SRL acceptance has been hindered because of concerns over SRL mathematical operations that may lead to inaccurate system readiness assessments.These inaccurate system readiness assessments are called readiness reversals.A new SRL calculation method using incidence matrices is proposed to alleviate these mathematical concerns.The presence of SRL readiness reversal is modeled for four SRL calculation methods across several system configurations.Logistic regression analysis demonstrates that the proposed Incidence Matrix SRL（IMSRL）method has a decreased presence of readiness reversal than other approaches suggested in the literature.Viable SRL methods will foster greater SRL adoption by systems engineering professionals and will support system development risk reduction goals.展开更多
This paper presents a quantitative approach to operational risk modeling and estimation of safety integrity levels,required for the deep water electric work class remotely operated vehicle with reference to ROSUB6000 ...This paper presents a quantitative approach to operational risk modeling and estimation of safety integrity levels,required for the deep water electric work class remotely operated vehicle with reference to ROSUB6000 developed by the National Institute of Ocean Technology,India.ROSUB6000 is used for carrying out bathymetric surveys,gas hydrate surveys,poly-metallic nodule exploration,salvage operations,and meeting emergency response situations.The system is expected to be in operation for a period of 300 h per year,and has to be extremely safe and reliable.Methods and models for the quantitative assessment of operational safety and estimation of safety integrity levels for ROV are seldom available in the deep water intervention industry.The safety instrumented functions implemented in the ROV should be able to meet the SIL requirements of specific mission.This study indicates that the required safety factors are implemented into the design of the state-of-the-art ROV ROSUB 6000,considering IEC 61508/61511 recommendations on Health,Safety and Environment and it is found that the system is able to meet the required SIL for seven identified functions.This paper gives the design and safety engineers in the ROV industry,an overview of the numerical operational risk assessment methods and safety-centered ROV engineering.展开更多
Wind and solar energy have seen significant decreases in the cost of these technologies over that last decade which has lead to increasing levels integrated into the grid.They also offer unique benefits such as no fue...Wind and solar energy have seen significant decreases in the cost of these technologies over that last decade which has lead to increasing levels integrated into the grid.They also offer unique benefits such as no fuel costs,quick installation,and no pollution.But as more variable renewable energy(VRE)such as wind and solar is integrated into electrical power systems.展开更多
This paper presents a fault-tolerant computer system. It is designed as a double 2-out-of-2 architecture based on component redundant technique. Also, a quantitative probabilistic model is presented for evaluating the...This paper presents a fault-tolerant computer system. It is designed as a double 2-out-of-2 architecture based on component redundant technique. Also, a quantitative probabilistic model is presented for evaluating the reliability, availability, maintainability and safety (RAMS) of this architecture. Hierarchical modeling method and Markov modeling method are used in RAMS analysis to evaluate the system characteristics. The double 2-out-of-2 system is compared with the other two systems, all voting triple modular redundancy (AVTMR) system and dual-duplex system. According to the result, the double 2-out-of-2 system has the highest dependability. Especially, the system can satisfy the safety integrity level (SIL) 4, which means the system’s probability of catastrophic failure less than or equal to 10-8 per hour, therefore, it can be applied to life critical systems such as high-speed railway systems.展开更多
文摘The end-Triassic （also Triassic-Jurassic） mass extinction severely affected life on planet Earth 200 million years ago. Paleoclimate change triggered by the volcanic eruptions of the Central Atlantic Magmatic Province （CAMP） caused a great loss of marine biodiversity, among which 96% coral genera were get lost. However, there is precious little detail on the paleoecology and growth forms lost between the latest Triassic extinction and the Early Jurassic recovery. Here a new pilot study was conducted by analyzing corallite integration levels among corals from the latest Triassic and Early Jurassic times. Integration levels in corals from the Late Triassic and Early Jurassic were determined through both the Paleobiology Database as well as from a comprehensive museum collection of fossil corals. Results suggest that in addition to a major loss of diversity following the end-Triassic mass extinction, there also was a significant loss of highly integrated corals as clearly evidenced by the coral data from the Early Jurassic. This confirms our hypothesis of paleoecological selectivity for corals following the end-Triassic mass extinction. This study highlights the importance of assigning sim- ple to advanced paleoecological characters with integration levels, which opens a useful approach to understanding of mass extinction and the dynamics of the recovery.
基金Under the auspices of National Key Research and Development Program(No.2023YFC3804001)National Natural Science Foundation of China(No.42201440)。
文摘Understanding the urban-rural development mechanism is critical for implementing rural revival and new-type urbanization.However,it remains a challenge to quantify the urban-rural integrated development level(URIDL)and its impact factors.Hence,we constructed an assessment system for the URIDL from spatial,economic,social,life,and ecological integration.The spatial autocorrelation and Spearman rank correlation coefficients were used to assess the spatiotemporal variation of the URIDL and the trade-off synergistic relationship among the subsystems at the provincial scale in China using socio-economic statistical data from 2000 to 2020.A spatial panel quantile regression model was used to analyze the driving mechanism.The results showed that the URIDL of China increased by 0.19%from 2000 to 2020,and a high-high(H-H)spatial agglomeration pattern occurred in the Yangtze River Delta and the Beijing-Tianjin-Hebei regions.Spatial integration significantly contributed to the other subsystems,whereas economic integration had a significant negative impact on the other subsystems in the eastern coastal and southwestern regions.Per capita Gross Domestic Product(GDP)improved the URIDL,whereas other factors,such as fiscal revenue decentralization,had inhibiting effects.Notably,the impact of factors on URIDL varies across different quantiles.Finally,we proposed policy recommendations for differentiated improvement of URIDL based on its evolution and regional development level during the research period.
基金supported by the National Key Research and Development Program(Grant No.2022YFB2803800)the National Natural Science Foundation of China(Grant No.U23A20376,62431024).
文摘The rapid advancement of the thin-film lithium niobate(LiNbO_(3))platform has established it as a premier choice for high-performance photonics integrated circuits.However,the scalability and cost-efficiency of this platform are hindered by the reliance on chip-level fabrication and integration for passive and active components,necessitating a robust wafer-level LiNbO_(3)heterogeneous integration platform.Despite its critical role in enabling ultrahigh-speed optical interconnects,as well as optical mmWave/THz sensing and communication,the realization of ultrahigh-speed photodiodes and optical coherent receivers on the LiNbO_(3)platform remains an unresolved challenge.This is primarily due to the challenges associated with the large-scale integration of direct-bandgap materials.To address these challenges,we have developed a scalable,high-speed InP-LiNbO_(3)wafer-level heterogeneous integration platform.This platform facilitates the fabrication of ultrahigh-speed photodiodes with a bandwidth of 140 GHz,capable of receiving high-quality 100-Gbaud pulse amplitude modulation(PAM4)signals.Moreover,we demonstrate a sevenchannel,single-polarization I–Q coherent receiver chip with an aggregate receiving capacity of 3.584 Tbit s^(-1).This coherent receiver exhibits a balanced detection bandwidth of 60 GHz and a common mode rejection ratio(CMRR)exceeding 20 dB.It achieves receiving capacities of 600 Gbit s^(-1)λ^(-1)with a 100-Gbaud 64-QAM signal and 512 Gbit s^(-1)λ^(-1)with a 128-Gbaud 16-QAM signal.Furthermore,energy consumption as low as 9.6 fJ bit^(-1) and 13.5 fJ bit^(-1) is achieved for 200 Gbit s^(-1)and 400 Gbit s^(-1)capacities,respectively.Our work provides a viable pathway toward enabling Pbps hyperscale data center interconnects,as well as optical mmWave/THz sensing and communication.
基金the National Key Research and Development Program of China(No.2023YFB3907001)the financial support from the National Natural Science Foundation of China(Nos.62371029,U2233217 and 62101019)the Civil Aviation Security Capacity Building Fund Project of China(Nos.CAAC Contract 2021(77)and CAAC Contract 2022(110)).
文摘Antenna Group Delay Variation(AGDV)is a hardware error source that affects the performance of Dual-Frequency Multi-Constellation(DFMC)Ground-based Augmentation System(GBAS),and these errors are difficult to distinguish from multipath errors.Currently,AGDV is usually modeled as a part of the multipath error,which is called the multipath-AGDV model.However,because of the inconsistency of AGDV and multipath when switching among different positioning modes of GBAS,and because the traditional model does not consider the impact of the azimuth on AGDV,using the traditional multipath-AGDV model will cause the protection levels to be inaccurately calculated.In this paper,azimuth-based modeling of AGDV is conducted by using anechoic chamber measurements.The biases and standard deviations of AGDV based on azimuths are analyzed and modeled,and the calculation method for the DFMC GBAS protection level is optimized.The results show that the azimuth-based AGDV model and protection level optimization algorithm can better avoid the error exceeding the protection level than the multipath-AGDV model.Compared with AGDV elevation model,the VPLs of the B1C signal are increased by 0.24 m and 0.06 m,and the VPLs of the B2a signal are reduced by 0.01 m and 0.16 m using the 100 s and 600 s DFree filtering positioning modes,respectively.The changes in the B1C and B2a protection levels reflect the changes in AGDV corresponding to the azimuth for the respective frequencies,further ensuring the integrity of airborne users,especially when they turn near the airport.
基金supported by the National Natural Science Foundation of China (70901074 71001104)
文摘An integration-centric approach is proposed to handle inadequate information in the system readiness level （SRL） assessment using the evidential reasoning （ER） algorithm. Current SRL assessment approaches cannot be applied to handle inadequate information as the input. The ER-based approach is proposed to synthesize inadequate input information and an integration-centric perspective is applied to reduce the computational complexity. Two case studies are performed to validate the efficiency of the proposed approach. And these studies are also performed to study how the inadequate information will affect the assessment result. And the differences caused by the system＇s structure. The importance of the system＇s structure in the SRL assessment is demonstrated and the contributions made in this study are summarized as conclusions.
文摘Proton therapy is the most advanced radiotherapy approach in the world,and causes less damage to normal human tissue than traditional radiotherapy.Because the treatment process produces a high-energy proton beam,the personnel safety interlock system mainly considers measures to protect personnel from radiation hazards during beam preparation and the beam release process.Unlike other safety interlock systems,the personnel safety interlock system designed in this study focuses on the safety and stability of the system itself.The hardware and software of important interlock control loops are designed and developed according to the requirements of Safety Integrity Level 3 specified by IEC61508.A set of redundant ring networks was developed to ensure that damage to a certain network line does not affect the normal operation of the system.A set of friendly operation interfaces and data storage systems were developed to ensure that the operator can monitor the data in real time and trace the data.The personnel safety interlock system mainly includes a beam enabling function,clearance function,and emergency stop function.The system was put into actual use and successfully ensured personnel safety.
基金supported by the National Natural Science Foundation of China(No.52171287,No.51779267,No.51707204)the National Key Research and Development Program of China(No.2019YFE0105100)+3 种基金the IKTPLUSS program of Research Council of Norway(No.309628)the Taishan Scholars Project(No.tsqn201909063)the Fundamental Research Funds for the Central Universities,that is,the Opening Fund of National Engineering Laboratory of Offshore Geophysical and Exploration Equipment(No.20CX02301A)the Science and Technology Support Plan for Youth Innovation of Universities in Shandong Province(No.2019KJB016)。
文摘In this study,a novel safety integrity level(SIL)determination methodology of safety instrumented systems(SISs)with parameter uncertainty is proposed by combining multistage dynamic Bayesian networks(DBNs)and Monte Carlo simulation.A multistage DBN model for SIL determination with multiple redundant cells is established.The models of function inspection test interval and function inspection test stages are alternately connected to form the multistage DBNs.The redundant cells can have different M out of N voting system architectures.An automatic modeling of conditional probability between nodes is developed.The SIL determination of SISs with parameter uncertainty is constructed by using the multistage DBNs and Monte Carlo simulation.A high-pressure SIS in the export of oil wellplatform is adopted to demonstrate the application of the proposed approach.The SIL and availability of the SIS and its subsystems are obtained.The influence of single subsystem on the SIL and availability of the SIS is studied.The influence of single redundant element on the SIL and availability of the subsystem is analyzed.A user-friendly SIL determination software with parameter uncertainty is developed on MATLAB graphical user interface.
文摘Worldwide Interoperability for Microwave Access(WiMAX)trusts Multiple Input Multiple Output-Orthogonal Frequency Division Multiplexing(MIMO-OFDM)combination for the deployment of physical layer functions and for connecting the medium access control to the wireless media.Even though Orthogonal Frequency Division Multiplexing(OFDM)facilitates reliable digital broadband transmission in the fading wireless channels,the presence of synchro-nization errors in the form of Carrier Frequency Offset(CFO)and Time Offset(TO)adversely affect the performance of OFDM based physical layers.The objective of this work is to improve the accuracy of the frequency and the time offset estimation in the WiMAX physical layer.A method to enhance the synchro-nization accuracy byfine-tuning the merit factor of the preamble sequence is sug-gested in this paper.Also,a new preamble with improved synchronization accuracy is proposed for the WiMAX system.The performance of the proposed preamble is evaluated in a Rayleigh fading channel and the results of simulations show that the Mean Square Error(MSE)in offset estimation is significantly reduced and it outperforms the standard WiMAX preamble.
文摘Contemporary system maturity assessment approaches have failed to provide robust quantitative system evaluations resulting in increased program costs and developmental risks.Standard assessment metrics,such as Technology Readiness Levels（TRL）,do not sufficiently evaluate increasingly complex systems.The System Readiness Level（SRL）is a newly developed system development metric that is a mathematical function of TRL and Integration Readiness Level（IRL） values for the components and connections of a particular system.SRL acceptance has been hindered because of concerns over SRL mathematical operations that may lead to inaccurate system readiness assessments.These inaccurate system readiness assessments are called readiness reversals.A new SRL calculation method using incidence matrices is proposed to alleviate these mathematical concerns.The presence of SRL readiness reversal is modeled for four SRL calculation methods across several system configurations.Logistic regression analysis demonstrates that the proposed Incidence Matrix SRL（IMSRL）method has a decreased presence of readiness reversal than other approaches suggested in the literature.Viable SRL methods will foster greater SRL adoption by systems engineering professionals and will support system development risk reduction goals.
文摘This paper presents a quantitative approach to operational risk modeling and estimation of safety integrity levels,required for the deep water electric work class remotely operated vehicle with reference to ROSUB6000 developed by the National Institute of Ocean Technology,India.ROSUB6000 is used for carrying out bathymetric surveys,gas hydrate surveys,poly-metallic nodule exploration,salvage operations,and meeting emergency response situations.The system is expected to be in operation for a period of 300 h per year,and has to be extremely safe and reliable.Methods and models for the quantitative assessment of operational safety and estimation of safety integrity levels for ROV are seldom available in the deep water intervention industry.The safety instrumented functions implemented in the ROV should be able to meet the SIL requirements of specific mission.This study indicates that the required safety factors are implemented into the design of the state-of-the-art ROV ROSUB 6000,considering IEC 61508/61511 recommendations on Health,Safety and Environment and it is found that the system is able to meet the required SIL for seven identified functions.This paper gives the design and safety engineers in the ROV industry,an overview of the numerical operational risk assessment methods and safety-centered ROV engineering.
文摘Wind and solar energy have seen significant decreases in the cost of these technologies over that last decade which has lead to increasing levels integrated into the grid.They also offer unique benefits such as no fuel costs,quick installation,and no pollution.But as more variable renewable energy(VRE)such as wind and solar is integrated into electrical power systems.
文摘This paper presents a fault-tolerant computer system. It is designed as a double 2-out-of-2 architecture based on component redundant technique. Also, a quantitative probabilistic model is presented for evaluating the reliability, availability, maintainability and safety (RAMS) of this architecture. Hierarchical modeling method and Markov modeling method are used in RAMS analysis to evaluate the system characteristics. The double 2-out-of-2 system is compared with the other two systems, all voting triple modular redundancy (AVTMR) system and dual-duplex system. According to the result, the double 2-out-of-2 system has the highest dependability. Especially, the system can satisfy the safety integrity level (SIL) 4, which means the system’s probability of catastrophic failure less than or equal to 10-8 per hour, therefore, it can be applied to life critical systems such as high-speed railway systems.
