The role of the rocket attitude control system is to execute the required maneuvers for guidance and ensure the stability of the rocket's flight attitude. Attitude control technology has always been one of the key...The role of the rocket attitude control system is to execute the required maneuvers for guidance and ensure the stability of the rocket's flight attitude. Attitude control technology has always been one of the key technologies for ensuring the success of rocket flights and has been a core topic in carrier rocket technology research. The Gravity-1 solid carrier rocket is the first solid rocket bundled rocket developed by China, adopting a configuration with four boosters and a core stage bundled together. During the actual flight process, the four booster engines are ignited first, and then, in the event of insufficient control force from the boosters, the core stage engine is ignited to participate in control. To address thrust asynchrony during the descent of the four boosters, an Extended State Observer(ESO) is employed in the control scheme for this flight segment. This involves real-time estimation and compensation of attitude parameters during flight, identification of thrust asynchrony among the boosters, and simultaneous determination of whether the core stage engine is ignited to participate in control.Through six degrees of freedom simulation analysis and Y1 flight test validation, this method has been proven to be correct and feasible.展开更多
In recent years,many studies have focused on the effects of global climate warming and increased nitrogen deposition on the structure and function of grassland ecosystem.However,there are still significant uncertainti...In recent years,many studies have focused on the effects of global climate warming and increased nitrogen deposition on the structure and function of grassland ecosystem.However,there are still significant uncertainties in the response mechanism of stability of plant community biomass in alpine meadows of the Qinghai-Xizang Plateau,China to these two major climate factors.Given this,based on field control experiments,this study systematically evaluated the effects of different levels of climate warming(W0(no warming),W1(air temperature increased by 0.47℃ or soil temperature increased by 0.61℃),W2(air temperature increased by 0.92℃ or soil temperature increased by 1.09℃),W3(air temperature increased by 1.44℃ or soil temperature increased by 1.95℃)),nitrogen deposition(N0(0 kg N/(hm^(2)·a)),N16(16 kg N/(hm^(2)·a)),and N32(32 kg N/(hm^(2)·a))),and their interactions on plant community biomass and its temporal stability,and explored its potential regulatory mechanisms.The results showed that the biomass of total community,Gramineae,and dominant species increased significantly with increasing temperature,but the biomass of common and rare species decreased significantly.Nitrogen deposition also significantly promoted the biomass accumulation of community and gramineous plants.Under the treatment of W3N32,the biomass of plant community,Gramineae,and dominant species reached the highest values,indicating that there was a synergistic effect under this treatment.Structural equation model showed that increasing temperature significantly decreased the stability of plant community biomass by reducing the stability of grass and dominant species biomass and weakening species asynchronism.Interaction of increased nitrogen deposition and temperature increased the biomass fluctuation of grass functional group,thus amplifying its negative influence on community stability.More attention should be paid to the response and regulatory mechanisms of dominant species and functional groups under global climate change.This study provides a theoretical basis for revealing the stability maintenance mechanism of alpine grassland and also provides scientific support for the development of future grassland ecosystem management and assessment.展开更多
Traditional strapdown inertial navigation system （SINS） algorithm studies are based on ideal measurements from gy- ros and accelerometers, while in the actual strapdown inertial measurement unit （SIMU）, time-async...Traditional strapdown inertial navigation system （SINS） algorithm studies are based on ideal measurements from gy- ros and accelerometers, while in the actual strapdown inertial measurement unit （SIMU）, time-asynchrony between each iner- tial sensor is inevitable. Testing principles and methods for time- asynchrony parameter identification are studied. Under the single- axis swaying environment, the relationships between the SINS platform drift rate and the gyro time-asynchrony are derived using the SINS attitude error equation. It is found that the gyro time- asynchrony error can be considered as a kind of pseudo-coning motion error caused by data processing. After gyro testing and synchronization, the single-axis tumble test method is introduced for the testing of each accelerometer time-asynchrony with respect to the ideal gyro triad. Accelerometer time-asynchrony parame- ter identification models are established using SINS specific force equation. Finally, all of the relative time-asynchrony parameters between inertial sensors are well identified by using fiber optic gyro SIMU as experimental verification.展开更多
In this paper, the asynchrony problem of distributed detection is analyzed and discussed.Two approaches are proposed and related results are given. It is shown that all fusion rules can beunified in the framework with...In this paper, the asynchrony problem of distributed detection is analyzed and discussed.Two approaches are proposed and related results are given. It is shown that all fusion rules can beunified in the framework with asynchrony which could be much ciooer to industrial practice.展开更多
Patient–ventilator asynchrony in Saudi Arabia practices is common,and more emphasis on how to mitigate such a clinical problem is needed.This letter is intended to shed the light on the current national evidence of p...Patient–ventilator asynchrony in Saudi Arabia practices is common,and more emphasis on how to mitigate such a clinical problem is needed.This letter is intended to shed the light on the current national evidence of patient–ventilator asynchrony and how to step ahead for better patients'ventilation management.展开更多
文摘The role of the rocket attitude control system is to execute the required maneuvers for guidance and ensure the stability of the rocket's flight attitude. Attitude control technology has always been one of the key technologies for ensuring the success of rocket flights and has been a core topic in carrier rocket technology research. The Gravity-1 solid carrier rocket is the first solid rocket bundled rocket developed by China, adopting a configuration with four boosters and a core stage bundled together. During the actual flight process, the four booster engines are ignited first, and then, in the event of insufficient control force from the boosters, the core stage engine is ignited to participate in control. To address thrust asynchrony during the descent of the four boosters, an Extended State Observer(ESO) is employed in the control scheme for this flight segment. This involves real-time estimation and compensation of attitude parameters during flight, identification of thrust asynchrony among the boosters, and simultaneous determination of whether the core stage engine is ignited to participate in control.Through six degrees of freedom simulation analysis and Y1 flight test validation, this method has been proven to be correct and feasible.
基金supported by the Key Research and Development and Transformation Plan of Qinghai Provincial Science and Technology Department(2024-NK-137)the Qinghai Province Science and Technology Commissioner Special Project(2024-NK-P28).
文摘In recent years,many studies have focused on the effects of global climate warming and increased nitrogen deposition on the structure and function of grassland ecosystem.However,there are still significant uncertainties in the response mechanism of stability of plant community biomass in alpine meadows of the Qinghai-Xizang Plateau,China to these two major climate factors.Given this,based on field control experiments,this study systematically evaluated the effects of different levels of climate warming(W0(no warming),W1(air temperature increased by 0.47℃ or soil temperature increased by 0.61℃),W2(air temperature increased by 0.92℃ or soil temperature increased by 1.09℃),W3(air temperature increased by 1.44℃ or soil temperature increased by 1.95℃)),nitrogen deposition(N0(0 kg N/(hm^(2)·a)),N16(16 kg N/(hm^(2)·a)),and N32(32 kg N/(hm^(2)·a))),and their interactions on plant community biomass and its temporal stability,and explored its potential regulatory mechanisms.The results showed that the biomass of total community,Gramineae,and dominant species increased significantly with increasing temperature,but the biomass of common and rare species decreased significantly.Nitrogen deposition also significantly promoted the biomass accumulation of community and gramineous plants.Under the treatment of W3N32,the biomass of plant community,Gramineae,and dominant species reached the highest values,indicating that there was a synergistic effect under this treatment.Structural equation model showed that increasing temperature significantly decreased the stability of plant community biomass by reducing the stability of grass and dominant species biomass and weakening species asynchronism.Interaction of increased nitrogen deposition and temperature increased the biomass fluctuation of grass functional group,thus amplifying its negative influence on community stability.More attention should be paid to the response and regulatory mechanisms of dominant species and functional groups under global climate change.This study provides a theoretical basis for revealing the stability maintenance mechanism of alpine grassland and also provides scientific support for the development of future grassland ecosystem management and assessment.
基金supported by the National Natural Science Foundation of China(61273333)
文摘Traditional strapdown inertial navigation system （SINS） algorithm studies are based on ideal measurements from gy- ros and accelerometers, while in the actual strapdown inertial measurement unit （SIMU）, time-asynchrony between each iner- tial sensor is inevitable. Testing principles and methods for time- asynchrony parameter identification are studied. Under the single- axis swaying environment, the relationships between the SINS platform drift rate and the gyro time-asynchrony are derived using the SINS attitude error equation. It is found that the gyro time- asynchrony error can be considered as a kind of pseudo-coning motion error caused by data processing. After gyro testing and synchronization, the single-axis tumble test method is introduced for the testing of each accelerometer time-asynchrony with respect to the ideal gyro triad. Accelerometer time-asynchrony parame- ter identification models are established using SINS specific force equation. Finally, all of the relative time-asynchrony parameters between inertial sensors are well identified by using fiber optic gyro SIMU as experimental verification.
文摘In this paper, the asynchrony problem of distributed detection is analyzed and discussed.Two approaches are proposed and related results are given. It is shown that all fusion rules can beunified in the framework with asynchrony which could be much ciooer to industrial practice.
文摘Patient–ventilator asynchrony in Saudi Arabia practices is common,and more emphasis on how to mitigate such a clinical problem is needed.This letter is intended to shed the light on the current national evidence of patient–ventilator asynchrony and how to step ahead for better patients'ventilation management.
