Gas chimneys,salt domes,and faults are vital to the movement of hydrocarbons within geological systems.Accurate identification of these geological features is crucial to modeling hydrocarbon resources.This study explo...Gas chimneys,salt domes,and faults are vital to the movement of hydrocarbons within geological systems.Accurate identification of these geological features is crucial to modeling hydrocarbon resources.This study explores the processes that have shaped the eastern Persian Gulf,focusing on salt diapir characteristics,origin,and fluid migration.Plate collisions between the Indian,Eurasian,and Arabian Plates have considerably impacted salt tectonics,developing key features such as the Hormuz salt,Qatar-South Fars Arch,and Zagros and Oman orogenic structures.Salt-related features were discerned through two-dimensional seismic data and drilling records,salt movement sequences were reconstructed,and fluid expulsion patterns were delineated using attribute preferences.The results of this study revealed that fractured substrates influenced by regional tectonic forces contribute to the creation of salt diapirs,which serve as conduits for guided fluid transport.Moreover,these results showed that gravity-driven downbuilding mainly controls salt flow,while the circular arrangement of salt structures results from regional stress and interactions between different salt sources.Distinct stress-induced basement incisions compounded by the hindrance of initial salt movement by the Qatar Arch further contribute to the complex salt structure geometry.Crucially,the uplift of the Qatar Arch and stresses from the Oman and Zagros orogenies profoundly affect the salt structure geometry and depositional patterns across diverse regions,resulting in circular salt structures and gas chimneys.This study offers valuable perspectives for oil and gas exploration and provides a comprehensive understanding of the regional dynamics governing salt tectonics and hydrocarbon ascent in the eastern Persian Gulf.展开更多
This study aimed to compare gait properties during level walking and during stair ascent and descent with varying loads. Fifteen healthy young men (mean age: 22.1 ± 1.6 years) walked while holding four different ...This study aimed to compare gait properties during level walking and during stair ascent and descent with varying loads. Fifteen healthy young men (mean age: 22.1 ± 1.6 years) walked while holding four different loads relative to each subject’s body mass (0, 20, 40 and 60% of body mass: BM) on their backs. Stance time, swing time, and double support times were selected as gait parameters. All parameters showed a maximal value during stair ascent and a minimum value during level walking. Stance and double support times increased significan- tly with each load during level walking and during stair ascent and descent. In conclusion, st- air ascent and descent creates more unstable movement than level walking regardless of the weight of the load. The effect of loads on gait increases with the weight of the load and becomes obvious once the load exceeds 60% of BM.展开更多
During the Yushu Earthquake on April 14,2010,a large number of rescuers from sea level or lowlands ascended to the quake areas very rapidly or rapidly less than 24 h. However,Yushu Earthquake is the highest quake in t...During the Yushu Earthquake on April 14,2010,a large number of rescuers from sea level or lowlands ascended to the quake areas very rapidly or rapidly less than 24 h. However,Yushu Earthquake is the highest quake in the world at altitudes between 3 750 m and 4 878 m where is a serious hypoxic environment. A high incidence of acute altitude illness was found in the unacclimatized rescuers;the mountain rescue operation changed as "rescue the rescuers". Lesson from the Yushu Earthquake is that the occurrence of acute altitude illness may be closely related to the ascent schedules. This prompted us to study the relationship between ascent rate and the incidence and severity of acute altitude illness;five different groups were compared. The first group was 42 sea level male young soldiers who ascended to quake area very rapidly within 8 h at 4 000 m;the second group was 48 sea level male young soldiers who ascended to 4 000 m rapidly less than 18 h;the third group was 66 acclimatized medical workers from 2 261 m who ascended to 4 000 m rapidly within 12 h;the fourth group was 56 Tibetan medical workers from 2 800 m who ascended to 4 000 m rapidly within 8 h;the fifth group was 50 male sea level workers who ascended to 4 000 m gradually over a period of 4 d. The results showed that the sea level rescuers ascended to 4 000 m very rapidly or rapidly had the highest incidence of acute mountain sickness (AMS) with the greatest AMS scores and the lowest arterial oxygen saturation (SaO2);the sea level workers ascended to 4 000 m gradually had moderate incidence of AMS with moderate AMS scores and SaO2 values;whereas the acclimatized and adapted rescuers had the lowest incidence of AMS,lowest AMS scores and higher SaO2;especially none AMS occurred in Tibetan rescuers. AMS score is inversely related to the ascent rate (r=-0.24,p< 0.001). Additionally,acute altitude illness is significantly influenced by altitude acclimatization. The ascent rate is inversely re- lated to the period of altitude acclimatization whereas the time of perfect recovered from AMS is positively correlated to the time taken to acclimatize. Generally,the best means of preventing acute altitude illness is slow and gradual ascent to high altitude,as this allows time for establishing altitude acclimatization and tolerance to the hypoxic environment. However,during an emergency circumstance,such as mountain rescue operation,the rescuers must rapidly ascend to high altitude,so a series of preventive strategies including pre-acclimatization,using some prophylactic drugs and oxygen supplementary are sorely necessary.展开更多
In [7], Cross showed that the spectrum of a linear relation T on a normed space satisfies the spectral mapping theorem. In this paper, we extend the notion of essential ascent and descent for an operator acting on a v...In [7], Cross showed that the spectrum of a linear relation T on a normed space satisfies the spectral mapping theorem. In this paper, we extend the notion of essential ascent and descent for an operator acting on a vector space to linear relations acting on Banach spaces. We focus to define and study the descent, essential descent, ascent and essential ascent spectrum of a linear relation everywhere defined on a Banach space X. In particular, we show that the corresponding spectrum satisfy the polynomial version of the spectral mapping theorem.展开更多
The calibration accuracy of High Resolution Infrared Radiation Sounder Mod. 2 (HIRS / 2) on NOAA-10 satellite is analyzed in this paper. The non-linear effect in the linear calibration curve induces a deviation of 1.5...The calibration accuracy of High Resolution Infrared Radiation Sounder Mod. 2 (HIRS / 2) on NOAA-10 satellite is analyzed in this paper. The non-linear effect in the linear calibration curve induces a deviation of 1.5 degrees (k) of brightness temperature in the tenth channel (8.3 um, water vapor absorption) of the HIRS/2 and the non-linear effect affects the other channels to a different extent. Based on analyzing non- linearity in two-point calibration curve, a tri-point calibration equation is given. A numerical test of effects of the linear and non-linear calibration models on the accuracy of atmospheric temperature retrievals is carried out.展开更多
In this paper, the ascent of 2 × 2 infinite dimensional Hamiltonian operators and a class of 4 × 4 infinite dimensional Hamiltonian operators are studied, and the conditions under which the ascent of 2 ×...In this paper, the ascent of 2 × 2 infinite dimensional Hamiltonian operators and a class of 4 × 4 infinite dimensional Hamiltonian operators are studied, and the conditions under which the ascent of 2 × 2 infinite dimensional Hamiltonian operator is 1 and the ascent of a class of 4 × 4 infinite dimensional Hamiltonian operators that arises in study of elasticity is2 are obtained. Concrete examples are given to illustrate the effectiveness of criterions.展开更多
To eliminate the load weight limit of carrier rockets and reduce the burden on support structures,in-orbit assembly is a key technology to make design of scattering a large diameter telescope into submirror modules,wh...To eliminate the load weight limit of carrier rockets and reduce the burden on support structures,in-orbit assembly is a key technology to make design of scattering a large diameter telescope into submirror modules,which requires smooth operation of assembly robots,and flexible force control technology is necessary. A ground demonstration system is presented for in-orbit assembly focusing on flexible force control. A six-dimensional force/torque sensor and its data acquisition system are used to compensate for gravity. For translation and rotation,an algorithm for flexible control is proposed. A ground transportation demonstration verifies accuracy and smoothness of flexible force control,and the transportation and assembly task is completed automatically. The proposed system is suitable for the development of in-orbit assembly robots.展开更多
Imaging altimeter(IALT)is a new type of radar altimeter system.In contrast to the conventional nadir-looking altimeters,such as HY-2 A altimeter,Jason-1/2,and TOPEX/Poseidon,IALT observes the earth surface at low inci...Imaging altimeter(IALT)is a new type of radar altimeter system.In contrast to the conventional nadir-looking altimeters,such as HY-2 A altimeter,Jason-1/2,and TOPEX/Poseidon,IALT observes the earth surface at low incident angles(2.5°–8°),so its swath is much wider and its spatial resolution is much higher than the previous altimeters.This paper presents a wind speed inversion method for the recently launched IALT onboard Tiangong-2 space station.Since the current calibration results of IALT do not agree well with the well-known wind geophysical model function at low incidence angles,a neural network is used to retrieve the ocean surface wind speed in this study.The wind speed inversion accuracy is evaluated by comparing with the ECMWF reanalysis wind speed,buoy wind speed,and in-situ ship measurements.The results show that the retrieved wind speed bias is about–0.21 m/s,and the root-mean-square(RMS)error is about 1.85 m/s.The wind speed accuracy of IALT meets the performance requirement.展开更多
Responsiveness is a challenge for space systems to sustain competitive advantage over al-ternate non-spaceborne technologies.For a satellite in its operational orbit,in-orbit responsiveness is defined as the capabilit...Responsiveness is a challenge for space systems to sustain competitive advantage over al-ternate non-spaceborne technologies.For a satellite in its operational orbit,in-orbit responsiveness is defined as the capability of the satellite to respond to a given demand in a timely manner.In this paper,it is shown that Average Wait Time(AWT) to pick up user demand from ground segment is the ap-propriate metric to evaluate the effect of ground segment location on in-orbit responsiveness of Low Earth Orbit(LEO) sunsynchronous satellites.This metric depends on pattern of ground segment access to satellite and distribution of user demands in time domain.A mathematical model is presented to determine pattern of ground segment access to satellite and concept of cumulative distribution function is used to simulate distribution of user demands for markets with different total demand scenarios.Monte Carlo simulations are employed to take account of uncertainty in distribution and total volume of user demands.Sampling error and standard deviation are used to ensure validity of AWT metric obtained from Monte Carlo simulations.Incorporation of the proposed metric in the ground segment site location process results in more responsive satellite systems which,in turn,lead to greater customer satisfaction levels and attractiveness of spaceborne systems for different applications.Finally,simula-tion results for a case study are presented.展开更多
The recent approval of pembrolizumab as second-line treatment for any solid tumor with high-level microsatellite instability or mismatch repair deficiency agnostic of tissue and origin1 has shattered a glass ceiling f...The recent approval of pembrolizumab as second-line treatment for any solid tumor with high-level microsatellite instability or mismatch repair deficiency agnostic of tissue and origin1 has shattered a glass ceiling for immune checkpoint inhibitors.No longer bound to a specific cancer diagnosis but rather a biomarker,pembrolizumab has heightened a burgeoning optimism towards the drug class.Yet how these agents should carve out additional展开更多
To evaluate the effect of acute high-altitude exposure on sensory and short-term memory using interactive software,we transported 30 volunteers in a sport utility vehicle to a 4280 m plateau within3 h.We measured thei...To evaluate the effect of acute high-altitude exposure on sensory and short-term memory using interactive software,we transported 30 volunteers in a sport utility vehicle to a 4280 m plateau within3 h.We measured their memory performance on the plain(initial arrival)and 3 h after arrival on the plateau using six measures.展开更多
The grazing incidence focusing X-ray pulsar telescope(iFXPT), as the main payload of the X-ray Pulsar Navigation Test Satellite(XPNAV-1), will have great significance on China's space scientific exploration and X-...The grazing incidence focusing X-ray pulsar telescope(iFXPT), as the main payload of the X-ray Pulsar Navigation Test Satellite(XPNAV-1), will have great significance on China's space scientific exploration and X-ray pulsar navigation. With PSR B0531+21(Crab Pulsar) as the observation target, the pulsar profile has been recovered based on the data obtained by iFXPT, realizing the main objective of "observing" PSR B0531+21 for the first time in China. This payload mainly consists of the Wolter-I X-ray optics, silicon drift detector, magnetic deflector, electronics, high-energy particle shield and high-stability structures. Currently, the iFXPT, with its good in-orbit performance, has obtained a considerable observation data. The effective area, sensitivity and energy response have been calibrated both on ground and in-orbit, demonstrating a high degree of consistency. Meanwhile, the in-orbit observation data and information for pulsar navigation has also been analyzed simultaneously. As a result, the feasibility of the exploration scheme and the performance of the telescope have been fully validated.展开更多
The FY-2F satellite recently passed its in-orbit test review and can be put into operational use. Experts from Chinese Academy of Sciences, China Meteorological Administration, CASC, China Electronics Technology Group...The FY-2F satellite recently passed its in-orbit test review and can be put into operational use. Experts from Chinese Academy of Sciences, China Meteorological Administration, CASC, China Electronics Technology Group Corporation, State Administration of Science, Technology and Industry for National Defense,展开更多
After the successful launch of Yaogan 14, the 25Nms control moment gyroscope onboard the Yaogan 14 satellite successfully finished the attitude maneuver commands to the satellite and operates in a normal state. The su...After the successful launch of Yaogan 14, the 25Nms control moment gyroscope onboard the Yaogan 14 satellite successfully finished the attitude maneuver commands to the satellite and operates in a normal state. The successful maiden use of the 25Nms gyroscope fills the gap in the field of small control moment gyroscopes in展开更多
基金supported by the National Natural Science Foundation of China(Nos.92055211,42249801)the China-ASEAN Maritime Cooperation Fund Project(No.12120100500017001)。
文摘Gas chimneys,salt domes,and faults are vital to the movement of hydrocarbons within geological systems.Accurate identification of these geological features is crucial to modeling hydrocarbon resources.This study explores the processes that have shaped the eastern Persian Gulf,focusing on salt diapir characteristics,origin,and fluid migration.Plate collisions between the Indian,Eurasian,and Arabian Plates have considerably impacted salt tectonics,developing key features such as the Hormuz salt,Qatar-South Fars Arch,and Zagros and Oman orogenic structures.Salt-related features were discerned through two-dimensional seismic data and drilling records,salt movement sequences were reconstructed,and fluid expulsion patterns were delineated using attribute preferences.The results of this study revealed that fractured substrates influenced by regional tectonic forces contribute to the creation of salt diapirs,which serve as conduits for guided fluid transport.Moreover,these results showed that gravity-driven downbuilding mainly controls salt flow,while the circular arrangement of salt structures results from regional stress and interactions between different salt sources.Distinct stress-induced basement incisions compounded by the hindrance of initial salt movement by the Qatar Arch further contribute to the complex salt structure geometry.Crucially,the uplift of the Qatar Arch and stresses from the Oman and Zagros orogenies profoundly affect the salt structure geometry and depositional patterns across diverse regions,resulting in circular salt structures and gas chimneys.This study offers valuable perspectives for oil and gas exploration and provides a comprehensive understanding of the regional dynamics governing salt tectonics and hydrocarbon ascent in the eastern Persian Gulf.
文摘This study aimed to compare gait properties during level walking and during stair ascent and descent with varying loads. Fifteen healthy young men (mean age: 22.1 ± 1.6 years) walked while holding four different loads relative to each subject’s body mass (0, 20, 40 and 60% of body mass: BM) on their backs. Stance time, swing time, and double support times were selected as gait parameters. All parameters showed a maximal value during stair ascent and a minimum value during level walking. Stance and double support times increased significan- tly with each load during level walking and during stair ascent and descent. In conclusion, st- air ascent and descent creates more unstable movement than level walking regardless of the weight of the load. The effect of loads on gait increases with the weight of the load and becomes obvious once the load exceeds 60% of BM.
基金"973"National Key Basic Research and Development Program(No.2012CB518202)Project of Qinghai Development of Science and Technology(No.2011-N-150)
文摘During the Yushu Earthquake on April 14,2010,a large number of rescuers from sea level or lowlands ascended to the quake areas very rapidly or rapidly less than 24 h. However,Yushu Earthquake is the highest quake in the world at altitudes between 3 750 m and 4 878 m where is a serious hypoxic environment. A high incidence of acute altitude illness was found in the unacclimatized rescuers;the mountain rescue operation changed as "rescue the rescuers". Lesson from the Yushu Earthquake is that the occurrence of acute altitude illness may be closely related to the ascent schedules. This prompted us to study the relationship between ascent rate and the incidence and severity of acute altitude illness;five different groups were compared. The first group was 42 sea level male young soldiers who ascended to quake area very rapidly within 8 h at 4 000 m;the second group was 48 sea level male young soldiers who ascended to 4 000 m rapidly less than 18 h;the third group was 66 acclimatized medical workers from 2 261 m who ascended to 4 000 m rapidly within 12 h;the fourth group was 56 Tibetan medical workers from 2 800 m who ascended to 4 000 m rapidly within 8 h;the fifth group was 50 male sea level workers who ascended to 4 000 m gradually over a period of 4 d. The results showed that the sea level rescuers ascended to 4 000 m very rapidly or rapidly had the highest incidence of acute mountain sickness (AMS) with the greatest AMS scores and the lowest arterial oxygen saturation (SaO2);the sea level workers ascended to 4 000 m gradually had moderate incidence of AMS with moderate AMS scores and SaO2 values;whereas the acclimatized and adapted rescuers had the lowest incidence of AMS,lowest AMS scores and higher SaO2;especially none AMS occurred in Tibetan rescuers. AMS score is inversely related to the ascent rate (r=-0.24,p< 0.001). Additionally,acute altitude illness is significantly influenced by altitude acclimatization. The ascent rate is inversely re- lated to the period of altitude acclimatization whereas the time of perfect recovered from AMS is positively correlated to the time taken to acclimatize. Generally,the best means of preventing acute altitude illness is slow and gradual ascent to high altitude,as this allows time for establishing altitude acclimatization and tolerance to the hypoxic environment. However,during an emergency circumstance,such as mountain rescue operation,the rescuers must rapidly ascend to high altitude,so a series of preventive strategies including pre-acclimatization,using some prophylactic drugs and oxygen supplementary are sorely necessary.
文摘In [7], Cross showed that the spectrum of a linear relation T on a normed space satisfies the spectral mapping theorem. In this paper, we extend the notion of essential ascent and descent for an operator acting on a vector space to linear relations acting on Banach spaces. We focus to define and study the descent, essential descent, ascent and essential ascent spectrum of a linear relation everywhere defined on a Banach space X. In particular, we show that the corresponding spectrum satisfy the polynomial version of the spectral mapping theorem.
文摘The calibration accuracy of High Resolution Infrared Radiation Sounder Mod. 2 (HIRS / 2) on NOAA-10 satellite is analyzed in this paper. The non-linear effect in the linear calibration curve induces a deviation of 1.5 degrees (k) of brightness temperature in the tenth channel (8.3 um, water vapor absorption) of the HIRS/2 and the non-linear effect affects the other channels to a different extent. Based on analyzing non- linearity in two-point calibration curve, a tri-point calibration equation is given. A numerical test of effects of the linear and non-linear calibration models on the accuracy of atmospheric temperature retrievals is carried out.
基金supported by the National Natural Science Foundation of China(Grant Nos.11101200 and 11371185)the Natural Science Foundation of Inner Mongolia Autonomous Region,China(Grant No.2013ZD01)
文摘In this paper, the ascent of 2 × 2 infinite dimensional Hamiltonian operators and a class of 4 × 4 infinite dimensional Hamiltonian operators are studied, and the conditions under which the ascent of 2 × 2 infinite dimensional Hamiltonian operator is 1 and the ascent of a class of 4 × 4 infinite dimensional Hamiltonian operators that arises in study of elasticity is2 are obtained. Concrete examples are given to illustrate the effectiveness of criterions.
基金Supported by the National Natural Science Foundation of China(No.11672290)
文摘To eliminate the load weight limit of carrier rockets and reduce the burden on support structures,in-orbit assembly is a key technology to make design of scattering a large diameter telescope into submirror modules,which requires smooth operation of assembly robots,and flexible force control technology is necessary. A ground demonstration system is presented for in-orbit assembly focusing on flexible force control. A six-dimensional force/torque sensor and its data acquisition system are used to compensate for gravity. For translation and rotation,an algorithm for flexible control is proposed. A ground transportation demonstration verifies accuracy and smoothness of flexible force control,and the transportation and assembly task is completed automatically. The proposed system is suitable for the development of in-orbit assembly robots.
基金The National Key Research and Development Program of China under contract No.2016YFC1401002the Key Special Project for Introduced Talents Team of Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou)under contract No.GML2019ZD0302the National Natural Science Foundation of China under contract No.41606202
文摘Imaging altimeter(IALT)is a new type of radar altimeter system.In contrast to the conventional nadir-looking altimeters,such as HY-2 A altimeter,Jason-1/2,and TOPEX/Poseidon,IALT observes the earth surface at low incident angles(2.5°–8°),so its swath is much wider and its spatial resolution is much higher than the previous altimeters.This paper presents a wind speed inversion method for the recently launched IALT onboard Tiangong-2 space station.Since the current calibration results of IALT do not agree well with the well-known wind geophysical model function at low incidence angles,a neural network is used to retrieve the ocean surface wind speed in this study.The wind speed inversion accuracy is evaluated by comparing with the ECMWF reanalysis wind speed,buoy wind speed,and in-situ ship measurements.The results show that the retrieved wind speed bias is about–0.21 m/s,and the root-mean-square(RMS)error is about 1.85 m/s.The wind speed accuracy of IALT meets the performance requirement.
基金Supported by the Research Council of Shahid Beheshti University,G. C.
文摘Responsiveness is a challenge for space systems to sustain competitive advantage over al-ternate non-spaceborne technologies.For a satellite in its operational orbit,in-orbit responsiveness is defined as the capability of the satellite to respond to a given demand in a timely manner.In this paper,it is shown that Average Wait Time(AWT) to pick up user demand from ground segment is the ap-propriate metric to evaluate the effect of ground segment location on in-orbit responsiveness of Low Earth Orbit(LEO) sunsynchronous satellites.This metric depends on pattern of ground segment access to satellite and distribution of user demands in time domain.A mathematical model is presented to determine pattern of ground segment access to satellite and concept of cumulative distribution function is used to simulate distribution of user demands for markets with different total demand scenarios.Monte Carlo simulations are employed to take account of uncertainty in distribution and total volume of user demands.Sampling error and standard deviation are used to ensure validity of AWT metric obtained from Monte Carlo simulations.Incorporation of the proposed metric in the ground segment site location process results in more responsive satellite systems which,in turn,lead to greater customer satisfaction levels and attractiveness of spaceborne systems for different applications.Finally,simula-tion results for a case study are presented.
文摘The recent approval of pembrolizumab as second-line treatment for any solid tumor with high-level microsatellite instability or mismatch repair deficiency agnostic of tissue and origin1 has shattered a glass ceiling for immune checkpoint inhibitors.No longer bound to a specific cancer diagnosis but rather a biomarker,pembrolizumab has heightened a burgeoning optimism towards the drug class.Yet how these agents should carve out additional
基金supported by a grant from the National Science Foundation of China(No.81301134,81371444)a research program from the logistics department of PLA(No.CLZ15C005)
文摘To evaluate the effect of acute high-altitude exposure on sensory and short-term memory using interactive software,we transported 30 volunteers in a sport utility vehicle to a 4280 m plateau within3 h.We measured their memory performance on the plain(initial arrival)and 3 h after arrival on the plateau using six measures.
文摘The grazing incidence focusing X-ray pulsar telescope(iFXPT), as the main payload of the X-ray Pulsar Navigation Test Satellite(XPNAV-1), will have great significance on China's space scientific exploration and X-ray pulsar navigation. With PSR B0531+21(Crab Pulsar) as the observation target, the pulsar profile has been recovered based on the data obtained by iFXPT, realizing the main objective of "observing" PSR B0531+21 for the first time in China. This payload mainly consists of the Wolter-I X-ray optics, silicon drift detector, magnetic deflector, electronics, high-energy particle shield and high-stability structures. Currently, the iFXPT, with its good in-orbit performance, has obtained a considerable observation data. The effective area, sensitivity and energy response have been calibrated both on ground and in-orbit, demonstrating a high degree of consistency. Meanwhile, the in-orbit observation data and information for pulsar navigation has also been analyzed simultaneously. As a result, the feasibility of the exploration scheme and the performance of the telescope have been fully validated.
文摘The FY-2F satellite recently passed its in-orbit test review and can be put into operational use. Experts from Chinese Academy of Sciences, China Meteorological Administration, CASC, China Electronics Technology Group Corporation, State Administration of Science, Technology and Industry for National Defense,
文摘After the successful launch of Yaogan 14, the 25Nms control moment gyroscope onboard the Yaogan 14 satellite successfully finished the attitude maneuver commands to the satellite and operates in a normal state. The successful maiden use of the 25Nms gyroscope fills the gap in the field of small control moment gyroscopes in