Based on the analysis of X^2 test of global land rainfall time series, it is found that the mean global land annual rainfall reduce significantly when El Nio events occur, and increase evidently in La Nia years. The i...Based on the analysis of X^2 test of global land rainfall time series, it is found that the mean global land annual rainfall reduce significantly when El Nio events occur, and increase evidently in La Nia years. The impacts of ENSO on the winter and autumn precipitation over eastern China are also notable. Usually, the rainfall of winter and autumn over southern China increases, and that over northern China decreases in El Nio years. The effects of ENSO on summer rainfall are not so significant as on autumn and winter rainfall in China. The summer precipitation of area to the north of the Yellow River often decreases in El Nio years. No evident relationship is found between ENSO and spring rainfall in China.展开更多
The influence of spring AO on the summer rainfall along the Yangtze River is investigated. The long-term rainfall observations are filtered to remove the low-frequency variations longer than 10 years. The inter-annual...The influence of spring AO on the summer rainfall along the Yangtze River is investigated. The long-term rainfall observations are filtered to remove the low-frequency variations longer than 10 years. The inter-annual components show a high correlation to AO in the last hundred years. The strongest correlation appears for May AO and summer rainfall with a value of -0.39, significant above the 99% confidence level. Associated with one standard deviation stronger May AO index, the rainfall over the Yangtze River to the southern Japan decreases by about 3%-9%, while, at the same time increases by about 3%-6% in the northern China and far-eastern Russia. The coherent changes in rainfall are significantly related to the East Asian summer jet stream in the upper troposphere. When there is stronger AO in spring, the jet stream tends to move polarward in summer, and leads the rainfall-belt to move northward too. That gives rise to a drier condition in the Yangtze River valley, wetter anomalies in northern China.展开更多
To determine the optimal or near optimal parameters of PID controller with incomplete derivation, a novel design method based on differential evolution （DE） algorithm is presented. The controller is called DE-PID co...To determine the optimal or near optimal parameters of PID controller with incomplete derivation, a novel design method based on differential evolution （DE） algorithm is presented. The controller is called DE-PID controller. To overcome the disadvantages of the integral performance criteria in the frequency domain such as IAE, ISE, and ITSE, a new performance criterion in the time domain is proposed. The optimization procedures employing the DE algorithm to search the optimal or near optimal PID controller parameters of a control system are demonstrated in detail. Three typical control systems are chosen to test and evaluate the adaptation and robustness of the proposed DE-PID controller. The simulation results show that the proposed approach has superior features of easy implementation, stable convergence characteristic, and good computational efficiency. Compared with the ZN, GA, and ASA, the proposed design method is indeed more efficient and robust in improving the step response of a control system.展开更多
Based on the NCEP/NCAR reanalysis data set, empirical orthogonal function analysis and correlation analysis have been carried out. Antarctic oscillation index (AOI) is defined as the difference between the zonal-mean ...Based on the NCEP/NCAR reanalysis data set, empirical orthogonal function analysis and correlation analysis have been carried out. Antarctic oscillation index (AOI) is defined as the difference between the zonal-mean monthly sea level pressure departures of 40°S and 65°S. Regional surface temperature and precipitation over the extratropical Southern Hemisphere have a close relationship with AOI.展开更多
The long-term integration with the Global Ocean-Atmosphere-Land System model of the State Key Laboratory of Atmospheric Sciences and Geophysical Fluid Dynamics (LASG), Institute of Atmospheric Physics(IAP), Chinese Ac...The long-term integration with the Global Ocean-Atmosphere-Land System model of the State Key Laboratory of Atmospheric Sciences and Geophysical Fluid Dynamics (LASG), Institute of Atmospheric Physics(IAP), Chinese Academy of Sciences has been used in the investigations on the relationship between the thermohaline circulation and climate variability. The results show that the strength of the North Atlantic Thermohaline circulation (THC) is negatively correlated with the North Atlantic Oscillation (NAO). Based on this kind of relationship, and also the instrument-measured climate record such as air pressure and sea surface temperature, the activity of the thermohaline circulation during the 20th century has been evaluated. The inferred variations of the strength of the THC is that, during two multi-decadal periods of 1867-1903 and 1934-1972, the THC is estimated to have been running stronger, whereas during the two periods of 1904-1933 and 1973-1994, it appears to have been weaker.展开更多
This paper provides a review of paleoclimate modeling activities in China. Rather than attempt to cover all topics, we have chosen a few climatic intervals and events judged to be particularly informative to the inter...This paper provides a review of paleoclimate modeling activities in China. Rather than attempt to cover all topics, we have chosen a few climatic intervals and events judged to be particularly informative to the international community. In historical climate simulations, changes in solar radiation and volcanic activity explain most parts of reconstructions over the last millennium prior to the industrial era, while atmospheric greenhouse gas concentrations play the most important role in the20 th century warming over China. There is a considerable model–data mismatch in the annual and boreal winter temperature change over China during the mid-Holocene [6000 years before present（ka BP）], while coupled models with an interactive ocean generally perform better than atmospheric models. For the Last Glacial Maximum（21 ka BP）, climate models successfully reproduce the surface cooling trend over China but fail to reproduce its magnitude, with a better performance for coupled models. At that time, reconstructed vegetation and western Pacific sea surface temperatures could have significantly affected the East Asian climate, and environmental conditions on the Qinghai–Tibetan Plateau were most likely very different to the present day. During the late Marine Isotope Stage 3（30–40 ka BP）, orbital forcing and Northern Hemisphere glaciation, as well as vegetation change in China, were likely responsible for East Asian climate change. On the tectonic scale,the Qinghai–Tibetan Plateau uplift, the Tethys Sea retreat, and the South China Sea expansion played important roles in the formation of the East Asian monsoon-dominant environment pattern during the late Cenozoic.展开更多
Hydrogen sulfide(H_(2)S)was initially recognized as a toxic gas and its biological functions in mammalian cells have been gradually discovered during the past decades.In the latest decade,numerous studies have reveale...Hydrogen sulfide(H_(2)S)was initially recognized as a toxic gas and its biological functions in mammalian cells have been gradually discovered during the past decades.In the latest decade,numerous studies have revealed that H_(2)S has versatile functions in plants as well.In this review,we summarize H_(2)Smediated sulfur metabolic pathways,as well as the progress in the recognition of its biological functions in plant growth and development,particularly its physiological functions in biotic and abiotic stress responses.Besides direct chemical reactions,nitric oxide(NO)and hydrogen peroxide(H_(2)O2)have complex relationships with H_(2)S in plant signaling,both of which mediate protein post-translational modification(PTM)to attack the cysteine residues.We also discuss recent progress in the research on the three types of PTMs and their biological functions in plants.Finally,we propose the relevant issues that need to be addressed in the future research.展开更多
Control parameters of original differential evolution （DE） are kept fixed throughout the entire evolutionary process. However, it is not an easy task to properly set control parameters in DE for different optiinizat...Control parameters of original differential evolution （DE） are kept fixed throughout the entire evolutionary process. However, it is not an easy task to properly set control parameters in DE for different optiinization problems. According to the relative position of two different individual vectors selected to generate a difference vector in the searching place, a self-adapting strategy for the scale factor F of the difference vector is proposed. In terms of the convergence status of the target vector in the current population, a self-adapting crossover probability constant CR strategy is proposed. Therefore, good target vectors have a lower CFI while worse target vectors have a large CFI. At the same time, the mutation operator is modified to improve the convergence speed. The performance of these proposed approaches are studied with the use of some benchmark problems and applied to the trajectory planning of a three-joint redundant manipulator. Finally, the experiment results show that the proposed approaches can greatly improve robustness and convergence speed.展开更多
Long departure-taxi-out time leads to significant airport surface congestion, fuel-burn costs, and excessive emissions of greenhouse gases. To reduce these undesirable effects, a Predicted taxi-out time-based Dynamic ...Long departure-taxi-out time leads to significant airport surface congestion, fuel-burn costs, and excessive emissions of greenhouse gases. To reduce these undesirable effects, a Predicted taxi-out time-based Dynamic Pushback Control(PDPC) method is proposed. The implementation of this method requires two steps: first, the taxi-out times for aircraft are predicted by the leastsquares support-vector regression approach of which the parameters are optimized by an introduced improved Firefly algorithm. Then, a dynamic pushback control model equipped with a linear gate-hold penalty function is built, along with a proposed iterative taxiway queue-threshold optimization algorithm for solving the model. A case study with data obtained from Beijing International airport(PEK) is presented. The taxi-out time prediction model achieves predictive accuracy within 3 min and 5 min by 84.71% and 95.66%, respectively. The results of the proposed pushback method show that total operation cost and fuel-burn cost achieve a 14.0% and 21.1%reduction, respectively, as compared to the traditional K-control policy.(3) From the perspective of implementation, using PDPC policy can significantly reduce the queue length in taxiway and taxi-out time. The total operation cost and fuel-burn cost can be curtailed by 37.2% and 52.1%,respectively, as compared to the non-enforcement of any pushback control mechanism. These results show that the proposed pushback control model can reduce fuel-burn costs and airport surface congestion effectively.展开更多
The emergence of quantum computer will threaten the security of existing public-key cryptosystems, including the Diffie Hellman key exchange protocol, encryption scheme and etc, and it makes the study of resistant qua...The emergence of quantum computer will threaten the security of existing public-key cryptosystems, including the Diffie Hellman key exchange protocol, encryption scheme and etc, and it makes the study of resistant quantum cryptography very urgent. This motivate us to design a new key exchange protocol and eneryption scheme in this paper. Firstly, some acknowledged mathematical problems was introduced, such as ergodic matrix problem and tensor decomposition problem, the two problems have been proved to NPC hard. From the computational complexity prospective, NPC problems have been considered that there is no polynomial-time quantum algorithm to solve them. From the algebraic structures prospective, non-commutative cryptography has been considered to resist quantum. The matrix and tensor operator we adopted also satisfied with this non-commutative algebraic structures, so they can be used as candidate problems for resisting quantum from perspective of computational complexity theory and algebraic structures. Secondly, a new problem was constructed based on the introduced problems in this paper, then a key exchange protocol and a public key encryption scheme were proposed based on it. Finally the security analysis, efficiency, recommended parameters, performance evaluation and etc. were also been given. The two schemes has the following characteristics, provable security,security bits can be scalable, to achieve high efficiency, quantum resistance, and etc.展开更多
Conflict Detection and Resolution（CD＆R） is the key to ensure aviation safety based on Trajectory Prediction（TP）. Uncertainties that affect aircraft motions cause difficulty in an accurate prediction of the trajec...Conflict Detection and Resolution（CD＆R） is the key to ensure aviation safety based on Trajectory Prediction（TP）. Uncertainties that affect aircraft motions cause difficulty in an accurate prediction of the trajectory, especially in the context of four-dimensional（4D） Trajectory-Based Operation（4DTBO）, which brings the uncertainty of pilot intent. This study draws on the idea of time geography, and turns the research focus of CD＆R from TP to an analysis of the aircraft reachable space constrained by 4D waypoint constraints. The concepts of space–time reachability of aircraft and space–time potential conflict space are proposed. A novel pre-CD＆R scheme for multiple aircraft is established. A key advantage of the scheme is that the uncertainty of pilot intent is accounted for via a Space-Time Prism（STP） for aircraft. Conflict detection is performed by verifying whether the STPs of aircraft intersect or not, and conflict resolution is performed by planning a conflict-free space–time trajectory avoiding intersection. Numerical examples are presented to validate the efficiency of the proposed scheme.展开更多
Four periods with predominated droughts are identified in 4―2 ka BP according to documentary data, namely 3.6―3.5, 3.1―3.0, 2.8―2.7, and 2.45―2.35 ka BP. Palaeo-environmental data indicated that droughts were pre...Four periods with predominated droughts are identified in 4―2 ka BP according to documentary data, namely 3.6―3.5, 3.1―3.0, 2.8―2.7, and 2.45―2.35 ka BP. Palaeo-environmental data indicated that droughts were predominated in 4―2 ka BP in the south of Northeast China, Inner-Mongolia, east of Qinghai-Tibetan Plateau, and South China. Modeling study shows that precession may be responsible for the occurrence of droughts in 4―2 ka BP, integrating the GCM with forcing of insolation.展开更多
Endowing flexible and adaptable fiber devices with light-emitting capabilities has the potential to revolutionize the current design philosophy of intelligent,wearable interactive devices.However,significant challenge...Endowing flexible and adaptable fiber devices with light-emitting capabilities has the potential to revolutionize the current design philosophy of intelligent,wearable interactive devices.However,significant challenges remain in developing fiber devices when it comes to achieving uniform and customizable light effects while utilizing lightweight hardware.Here,we introduce a mass-produced,wearable,and interactive photochromic fiber that provides uniform multicolored light control.We designed independent waveguides inside the fiber to maintain total internal reflection of light as it traverses the fiber.The impact of excessive light leakage on the overall illuminance can be reduced by utilizing the saturable absorption effect of fluorescent materials to ensure light emission uniformity along the transmission direction.In addition,we coupled various fluorescent composite materials inside the fiber to achieve artificially controllable spectral radiation of multiple color systems in a single fiber.We prepared fibers on mass-produced kilometer-long using the thermal drawing method.The fibers can be directly integrated into daily wearable devices or clothing in various patterns and combined with other signal input components to control and display patterns as needed.This work provides a new perspective and inspiration to the existing field of fiber display interaction,paving the way for future human–machine integration.展开更多
-Using the COADS data set of sea surface temperature in the Equatorial Eastern Pacific, thirty one El Nino events and twenty four anti -El Nino events were identified for the period from 1854 to 1987. The results were...-Using the COADS data set of sea surface temperature in the Equatorial Eastern Pacific, thirty one El Nino events and twenty four anti -El Nino events were identified for the period from 1854 to 1987. The results were compared with those of the other authors. The El Nino events (or anti -El Nino events ) are classified into two groups according to the timing of occrrence of the events: one starts at the first half of a year, another begins at the second half of a year. Both 1982-1983 and 1986-1987 events fall into the second group, which are characterized by the eastward migration of the positive anomaly of the sea surface temperature and the significant increasing of the anomaly in September or October.展开更多
Hydrogen sulfide （H2S）, a colorless gas with a foul odor, has been known for hundreds of years as a toxic environmental pollutant. Recently, H2S has been recognized as the third gasotransmitter after nitric oxide an...Hydrogen sulfide （H2S）, a colorless gas with a foul odor, has been known for hundreds of years as a toxic environmental pollutant. Recently, H2S has been recognized as the third gasotransmitter after nitric oxide and carbon monoxide, with similar biological functions.展开更多
文摘Based on the analysis of X^2 test of global land rainfall time series, it is found that the mean global land annual rainfall reduce significantly when El Nio events occur, and increase evidently in La Nia years. The impacts of ENSO on the winter and autumn precipitation over eastern China are also notable. Usually, the rainfall of winter and autumn over southern China increases, and that over northern China decreases in El Nio years. The effects of ENSO on summer rainfall are not so significant as on autumn and winter rainfall in China. The summer precipitation of area to the north of the Yellow River often decreases in El Nio years. No evident relationship is found between ENSO and spring rainfall in China.
基金This work was supported by the Natioal Natural Science Foundation of China (Grant No. 40105007)the National Key Basic Research and Development Program (Grant No. G1998040900).
文摘The influence of spring AO on the summer rainfall along the Yangtze River is investigated. The long-term rainfall observations are filtered to remove the low-frequency variations longer than 10 years. The inter-annual components show a high correlation to AO in the last hundred years. The strongest correlation appears for May AO and summer rainfall with a value of -0.39, significant above the 99% confidence level. Associated with one standard deviation stronger May AO index, the rainfall over the Yangtze River to the southern Japan decreases by about 3%-9%, while, at the same time increases by about 3%-6% in the northern China and far-eastern Russia. The coherent changes in rainfall are significantly related to the East Asian summer jet stream in the upper troposphere. When there is stronger AO in spring, the jet stream tends to move polarward in summer, and leads the rainfall-belt to move northward too. That gives rise to a drier condition in the Yangtze River valley, wetter anomalies in northern China.
基金the National Natural Science Foundation of China (60375001)the Scientific Research Foundation of Hunan Provincial Education Department (05B016).
文摘To determine the optimal or near optimal parameters of PID controller with incomplete derivation, a novel design method based on differential evolution （DE） algorithm is presented. The controller is called DE-PID controller. To overcome the disadvantages of the integral performance criteria in the frequency domain such as IAE, ISE, and ITSE, a new performance criterion in the time domain is proposed. The optimization procedures employing the DE algorithm to search the optimal or near optimal PID controller parameters of a control system are demonstrated in detail. Three typical control systems are chosen to test and evaluate the adaptation and robustness of the proposed DE-PID controller. The simulation results show that the proposed approach has superior features of easy implementation, stable convergence characteristic, and good computational efficiency. Compared with the ZN, GA, and ASA, the proposed design method is indeed more efficient and robust in improving the step response of a control system.
文摘Based on the NCEP/NCAR reanalysis data set, empirical orthogonal function analysis and correlation analysis have been carried out. Antarctic oscillation index (AOI) is defined as the difference between the zonal-mean monthly sea level pressure departures of 40°S and 65°S. Regional surface temperature and precipitation over the extratropical Southern Hemisphere have a close relationship with AOI.
文摘The long-term integration with the Global Ocean-Atmosphere-Land System model of the State Key Laboratory of Atmospheric Sciences and Geophysical Fluid Dynamics (LASG), Institute of Atmospheric Physics(IAP), Chinese Academy of Sciences has been used in the investigations on the relationship between the thermohaline circulation and climate variability. The results show that the strength of the North Atlantic Thermohaline circulation (THC) is negatively correlated with the North Atlantic Oscillation (NAO). Based on this kind of relationship, and also the instrument-measured climate record such as air pressure and sea surface temperature, the activity of the thermohaline circulation during the 20th century has been evaluated. The inferred variations of the strength of the THC is that, during two multi-decadal periods of 1867-1903 and 1934-1972, the THC is estimated to have been running stronger, whereas during the two periods of 1904-1933 and 1973-1994, it appears to have been weaker.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDB03020602)supported by the Key Directional Program of the Knowledge-innovation Project of the Chinese Academy of Sciences (Grant No. KZCX2–YW–338– 2)+2 种基金supported by the National Basic Research Program of China (Grant No. 2007CB815901)supported by the National Basic Research Program of China (Grant No. 2010CB950102)supported by the National Natural Science Foundation of China (Grant No. 40875043)
文摘This paper provides a review of paleoclimate modeling activities in China. Rather than attempt to cover all topics, we have chosen a few climatic intervals and events judged to be particularly informative to the international community. In historical climate simulations, changes in solar radiation and volcanic activity explain most parts of reconstructions over the last millennium prior to the industrial era, while atmospheric greenhouse gas concentrations play the most important role in the20 th century warming over China. There is a considerable model–data mismatch in the annual and boreal winter temperature change over China during the mid-Holocene [6000 years before present（ka BP）], while coupled models with an interactive ocean generally perform better than atmospheric models. For the Last Glacial Maximum（21 ka BP）, climate models successfully reproduce the surface cooling trend over China but fail to reproduce its magnitude, with a better performance for coupled models. At that time, reconstructed vegetation and western Pacific sea surface temperatures could have significantly affected the East Asian climate, and environmental conditions on the Qinghai–Tibetan Plateau were most likely very different to the present day. During the late Marine Isotope Stage 3（30–40 ka BP）, orbital forcing and Northern Hemisphere glaciation, as well as vegetation change in China, were likely responsible for East Asian climate change. On the tectonic scale,the Qinghai–Tibetan Plateau uplift, the Tethys Sea retreat, and the South China Sea expansion played important roles in the formation of the East Asian monsoon-dominant environment pattern during the late Cenozoic.
基金supported by the National Natural Science Foundation of China(31670267,32070214)the Fundamental Research Funds for the Central Universities(2662020SKY008)。
文摘Hydrogen sulfide(H_(2)S)was initially recognized as a toxic gas and its biological functions in mammalian cells have been gradually discovered during the past decades.In the latest decade,numerous studies have revealed that H_(2)S has versatile functions in plants as well.In this review,we summarize H_(2)Smediated sulfur metabolic pathways,as well as the progress in the recognition of its biological functions in plant growth and development,particularly its physiological functions in biotic and abiotic stress responses.Besides direct chemical reactions,nitric oxide(NO)and hydrogen peroxide(H_(2)O2)have complex relationships with H_(2)S in plant signaling,both of which mediate protein post-translational modification(PTM)to attack the cysteine residues.We also discuss recent progress in the research on the three types of PTMs and their biological functions in plants.Finally,we propose the relevant issues that need to be addressed in the future research.
基金This work was supported by the National Natural Science Foundation of China(No.60375001)the High School Doctoral Foundation of China(NO.20030532004).
文摘Control parameters of original differential evolution （DE） are kept fixed throughout the entire evolutionary process. However, it is not an easy task to properly set control parameters in DE for different optiinization problems. According to the relative position of two different individual vectors selected to generate a difference vector in the searching place, a self-adapting strategy for the scale factor F of the difference vector is proposed. In terms of the convergence status of the target vector in the current population, a self-adapting crossover probability constant CR strategy is proposed. Therefore, good target vectors have a lower CFI while worse target vectors have a large CFI. At the same time, the mutation operator is modified to improve the convergence speed. The performance of these proposed approaches are studied with the use of some benchmark problems and applied to the trajectory planning of a three-joint redundant manipulator. Finally, the experiment results show that the proposed approaches can greatly improve robustness and convergence speed.
基金partially supported by the National Natural Science Foundation of China-Civil Aviation Joint Fund(Nos.U1533203,U1233124.)
文摘Long departure-taxi-out time leads to significant airport surface congestion, fuel-burn costs, and excessive emissions of greenhouse gases. To reduce these undesirable effects, a Predicted taxi-out time-based Dynamic Pushback Control(PDPC) method is proposed. The implementation of this method requires two steps: first, the taxi-out times for aircraft are predicted by the leastsquares support-vector regression approach of which the parameters are optimized by an introduced improved Firefly algorithm. Then, a dynamic pushback control model equipped with a linear gate-hold penalty function is built, along with a proposed iterative taxiway queue-threshold optimization algorithm for solving the model. A case study with data obtained from Beijing International airport(PEK) is presented. The taxi-out time prediction model achieves predictive accuracy within 3 min and 5 min by 84.71% and 95.66%, respectively. The results of the proposed pushback method show that total operation cost and fuel-burn cost achieve a 14.0% and 21.1%reduction, respectively, as compared to the traditional K-control policy.(3) From the perspective of implementation, using PDPC policy can significantly reduce the queue length in taxiway and taxi-out time. The total operation cost and fuel-burn cost can be curtailed by 37.2% and 52.1%,respectively, as compared to the non-enforcement of any pushback control mechanism. These results show that the proposed pushback control model can reduce fuel-burn costs and airport surface congestion effectively.
基金the National Natural Science Foundation of China，the State Key Program of National Natural Science of China，the Major Research Plan of the National Natural Science Foundation of China，Major State Basic Research Development Program of China (973 Program)，the Hubei Natural Science Foundation of China
文摘The emergence of quantum computer will threaten the security of existing public-key cryptosystems, including the Diffie Hellman key exchange protocol, encryption scheme and etc, and it makes the study of resistant quantum cryptography very urgent. This motivate us to design a new key exchange protocol and eneryption scheme in this paper. Firstly, some acknowledged mathematical problems was introduced, such as ergodic matrix problem and tensor decomposition problem, the two problems have been proved to NPC hard. From the computational complexity prospective, NPC problems have been considered that there is no polynomial-time quantum algorithm to solve them. From the algebraic structures prospective, non-commutative cryptography has been considered to resist quantum. The matrix and tensor operator we adopted also satisfied with this non-commutative algebraic structures, so they can be used as candidate problems for resisting quantum from perspective of computational complexity theory and algebraic structures. Secondly, a new problem was constructed based on the introduced problems in this paper, then a key exchange protocol and a public key encryption scheme were proposed based on it. Finally the security analysis, efficiency, recommended parameters, performance evaluation and etc. were also been given. The two schemes has the following characteristics, provable security,security bits can be scalable, to achieve high efficiency, quantum resistance, and etc.
基金financial support from the Civil Aviation Joint Funds of the National Natural Science Foundation of China (No’s.U1533203,61179069)
文摘Conflict Detection and Resolution（CD＆R） is the key to ensure aviation safety based on Trajectory Prediction（TP）. Uncertainties that affect aircraft motions cause difficulty in an accurate prediction of the trajectory, especially in the context of four-dimensional（4D） Trajectory-Based Operation（4DTBO）, which brings the uncertainty of pilot intent. This study draws on the idea of time geography, and turns the research focus of CD＆R from TP to an analysis of the aircraft reachable space constrained by 4D waypoint constraints. The concepts of space–time reachability of aircraft and space–time potential conflict space are proposed. A novel pre-CD＆R scheme for multiple aircraft is established. A key advantage of the scheme is that the uncertainty of pilot intent is accounted for via a Space-Time Prism（STP） for aircraft. Conflict detection is performed by verifying whether the STPs of aircraft intersect or not, and conflict resolution is performed by planning a conflict-free space–time trajectory avoiding intersection. Numerical examples are presented to validate the efficiency of the proposed scheme.
基金Sponsored by the National Natural Science Foundation of China (Grant No. 40331010)
文摘Four periods with predominated droughts are identified in 4―2 ka BP according to documentary data, namely 3.6―3.5, 3.1―3.0, 2.8―2.7, and 2.45―2.35 ka BP. Palaeo-environmental data indicated that droughts were predominated in 4―2 ka BP in the south of Northeast China, Inner-Mongolia, east of Qinghai-Tibetan Plateau, and South China. Modeling study shows that precession may be responsible for the occurrence of droughts in 4―2 ka BP, integrating the GCM with forcing of insolation.
基金supported by the National Natural Science Foundation of China(Grant No.62175082)the National Key Research and Development Program of China(Grant No.2022YFB3805800)the Multidisciplinary Research Support Program of Huazhong University of Science and Technology(Grant No.2023JCYJ039).
文摘Endowing flexible and adaptable fiber devices with light-emitting capabilities has the potential to revolutionize the current design philosophy of intelligent,wearable interactive devices.However,significant challenges remain in developing fiber devices when it comes to achieving uniform and customizable light effects while utilizing lightweight hardware.Here,we introduce a mass-produced,wearable,and interactive photochromic fiber that provides uniform multicolored light control.We designed independent waveguides inside the fiber to maintain total internal reflection of light as it traverses the fiber.The impact of excessive light leakage on the overall illuminance can be reduced by utilizing the saturable absorption effect of fluorescent materials to ensure light emission uniformity along the transmission direction.In addition,we coupled various fluorescent composite materials inside the fiber to achieve artificially controllable spectral radiation of multiple color systems in a single fiber.We prepared fibers on mass-produced kilometer-long using the thermal drawing method.The fibers can be directly integrated into daily wearable devices or clothing in various patterns and combined with other signal input components to control and display patterns as needed.This work provides a new perspective and inspiration to the existing field of fiber display interaction,paving the way for future human–machine integration.
文摘-Using the COADS data set of sea surface temperature in the Equatorial Eastern Pacific, thirty one El Nino events and twenty four anti -El Nino events were identified for the period from 1854 to 1987. The results were compared with those of the other authors. The El Nino events (or anti -El Nino events ) are classified into two groups according to the timing of occrrence of the events: one starts at the first half of a year, another begins at the second half of a year. Both 1982-1983 and 1986-1987 events fall into the second group, which are characterized by the eastward migration of the positive anomaly of the sea surface temperature and the significant increasing of the anomaly in September or October.
文摘Hydrogen sulfide （H2S）, a colorless gas with a foul odor, has been known for hundreds of years as a toxic environmental pollutant. Recently, H2S has been recognized as the third gasotransmitter after nitric oxide and carbon monoxide, with similar biological functions.
