Combined with recent historical climate data and two periods of land use datasets from remote sensing data, we test the net primary productivity (NPP) data sets in North Chinamodelled by the satellite data-driven Glob...Combined with recent historical climate data and two periods of land use datasets from remote sensing data, we test the net primary productivity (NPP) data sets in North Chinamodelled by the satellite data-driven Global Production Efficiency Model (GLO-PEM) for detecting thewidespread spatial and temporal characteristics of the impacts of climate and land use change onthe regional NPP. Our results show that over the past 20 years, the mean annual temperature in thestudy region has remarkably increased by more than 0.064 ℃, but over the same period, there hasbeen a 1.49 mm decrease in annual precipitation and decrease in NPP by an annual rate of 6.9 TgC.The NPP changes in the study region were greatly affected by the average temperature andprecipitation by ten-day periods as well as the seasonal temperature and precipitation in the studyregion. The correlation between seasonal NPP and seasonal precipitation and temperature is highlyconsistent with land cover spatially, and the correlation coefficient changes with the changes ofvegetation types. The analysis reveals that the related areas in land use change only take up 5.45%of the whole studied region, so the climate changes dominate the impacts on the NPP in the wholestudy region (90% of the total). However, land use plays an absolute dominative role in areas withland cover changes, accounting for 97% of the total. From 1981 to 2000, the NPP in the whole studyregion remarkably reduced due to obvious precipitation decrease and temperature rise. Between twoperiods of land use (about 10 years), the changes in climate are predicted to promote a decrease inNPP by 78 ( + -0.6) TgC, and integrated impacts of climate changes and land use to promote adecrease in NPP by 87(+-0.8) TgC.展开更多
Constellations design for regional terrestrial-satellite network can strengthen the coverage for incomplete terrestrial cellular network. In this paper, a regional satellite constellation design scheme with multiple f...Constellations design for regional terrestrial-satellite network can strengthen the coverage for incomplete terrestrial cellular network. In this paper, a regional satellite constellation design scheme with multiple feature points and multiple optimization indicators is proposed by comprehensively considering multi-objective optimization and genetic algorithm, and "the Belt and Road" model is presented in the way of dividing over 70 nations into three regular target areas. Following this, we formulate the optimization model and devise a multi-objective genetic algorithm suited for the regional area with the coverage rate under simulating, computing and determining. Meanwhile, the total number of satellites in the constellation is reduced by calculating the ratio of actual coverage of a single-orbit constellation and the area of targets. Moreover, the constellations' performances of the proposed scheme are investigated with the connection of C++ and Satellite Tool Kit(STK). Simulation results show that the designed satellite constellations can achieve a good coverage of the target areas.展开更多
In this paper, the major objective is to build a global dynamic network model to assess the global health condition .First use the PSR model and Analytic hierarchy process （AHP） to calculate the internal health stat...In this paper, the major objective is to build a global dynamic network model to assess the global health condition .First use the PSR model and Analytic hierarchy process （AHP） to calculate the internal health status of some regions, and then establish a global network model which links each region together to figure out the global health status. Finally, taking the human influence into consideration, the degree of the earth＇s health can be figured out in a more accurate way.展开更多
Using earth satellite observation means, remote sensing information distilled technique and regional research production, we have roundly analyzed and made an integrated evaluation about the Lop Nur nuclear test field...Using earth satellite observation means, remote sensing information distilled technique and regional research production, we have roundly analyzed and made an integrated evaluation about the Lop Nur nuclear test field in western China. This product reveals the rarely-known nuke explosion effect and response events of geology conditions. It also offers us legible and practical first-hand materials about human extreme effects, important engineering environment and intimidating influence process. By excavating and appraising the materials gradually on the natural environment factors changing in the test field through macroscopic elimination and typical filtration, it can supply basic scientific data for security of national nuclear usage, appraising the nuclear environment synthetically and developing nuclear strategy expediently.展开更多
BeiDou regional navigation satellite system （BDS） also called BeiDou-2 has been in full operation since December 27, 2012. It consists of 14 satellites, including 5 satellites in Geostationary Orbit （GEO）, 5 satel...BeiDou regional navigation satellite system （BDS） also called BeiDou-2 has been in full operation since December 27, 2012. It consists of 14 satellites, including 5 satellites in Geostationary Orbit （GEO）, 5 satellites in Inclined Geosynchronous Orbit （IGSO）, and 4 satellites in Medium Earth Orbit （MEO）. In this paper, its basic navigation and positioning performance are evaluated preliminarily by the real data collected in Beijing, including satellite visibility, Position Dilution of Precision （PDOP） value, the precision of code and carrier phase measurements, the accuracy of single point positioning and differential position- ing and ambiguity resolution （AR） performance, which are also compared with those of GPS. It is shown that the precision of BDS code and carrier phase measurements are about 33 cm and 2 mm, respectively, which are comparable to those of GPS, and the accuracy of BDS single point positioning has satisfied the design requirement. The real-time kinematic positioning is also feasible by BDS alolae in the opening condition, since its fixed rate and reliability of single-epoch dual-frequency AR is comparable to those of GPS. The accuracy of BDS carrier phase differential positioning is better than 1 cm for a very short baseline of 4.2 m and 3 cm for a short baseline of 8.2 km, which is on the same level with that of GPS. For the combined BDS and GPS, the fixed rate and reliability of single-epoch AR and the positioning accuracy are improved significantly. The accu- racy of BDS/GPS carrier phase differential positioning is about 35 and 20 % better than that of GPS for two short baseline tests in this study. The accuracy of BDS code differential positioning is better than 2.5 m. However it is worse than that of GPS, which may result from large code multipath errors of BDS GEO satellite measurements.展开更多
Constellations of regional satellite navigation systems are usually constituted of geostationary satellites (GEO) and inclined geostationary satellites (IGSO) for better service availability. Analysis of real data sho...Constellations of regional satellite navigation systems are usually constituted of geostationary satellites (GEO) and inclined geostationary satellites (IGSO) for better service availability. Analysis of real data shows that the pseudorange measurements of these two types of satellites contain significant multipath errors and code noise, and the multipath for GEO is extremely serious, which is harmful to system services. In contrast, multipath error of carrier phase measurements is less than 3 cm, which is smaller than the multipath of pseudorange measurements by two orders of magnitude. Using a particular combination of pseudorange and dual-frequency carrier phase measurements, the pseudorange multipath errors are detected, and their time varying features are analyzed. A real-time multipath correction algorithm is proposed in this paper, which is called CNMC (Code Noise and Multipath Correction). The algorithm decreases the influence of the multipath error and therefore ensures the performance of the system. Data processing experiments show that the multipath error level may be reduced from 0.5 m to 0.15 m by using this algorithm, and 60% of GEO multipath errors and 42% of IGSO multipath errors are successfully corrected with CNMC. Positioning experiments are performed with a constellation of 3 GEO plus 3 IGSO satellites. For dual-frequency users the East-West position accuracy is improved from 1.31 m to 0.94 m by using the CNMC algorithm, the South-North position accuracy is improved from 2.62 m to 2.29 m, and the vertical position accuracy is improved from 4.25 m to 3.05 m. After correcting multipath errors, the three-dimensional position accuracy is improved from 5.16 m to 3.94 m.展开更多
CHAMP satellite data and ground-based magnetic observations are used and combined to map the lithospheric magnetic field over China by means of the revised spherical cap harmonic analysis(R-SHCA)modeling technique.The...CHAMP satellite data and ground-based magnetic observations are used and combined to map the lithospheric magnetic field over China by means of the revised spherical cap harmonic analysis(R-SHCA)modeling technique.The magnetic field is described to a spatial resolution of 150 km at the mean Earth’s radius,which represents a good compromise between the resolutions afforded by surface and satellite data.We compare the magnetic anomalies modeled at the regional scale with composite regions containing large-scale of tectonic structures.These regions,including the Tarim Basin and the Tibetan Plateau,are correlated with regional magnetic anomalies at satellite altitude but contain a significant number of small-scale and complex magnetic structures at the mean Earth’s radius.These magnetic anomalies are globally consistent with the known geological features in China but also offer a way to delineate the contours of the geological blocks and to discuss the connection between magnetic anomalies and the heat flow distribution in this region.展开更多
The short-pulse TDMA signal is an excellent solution to the near-far problem in the pseudolite augmentation systems,and the pulse duty cycle is an important element in the solution.This paper aims at designing the dut...The short-pulse TDMA signal is an excellent solution to the near-far problem in the pseudolite augmentation systems,and the pulse duty cycle is an important element in the solution.This paper aims at designing the duty cycle of the pseudolite pulse signals with a theoretical method.At first,the scope of the duty cycle is derived theoretically with the object of ensuring the reception of both the pseudolite signals and the satellite signals,and the expression for the theoretical upper limit is given.Then based on the proposed expression,the duty cycles of Galileo pseudolite pulse signals are designed.The theoretical upper limit can guide the design of the short-pulse TDMA pseudolite signals.展开更多
Objective: To assess the quality of the first batch of Chinese evidence-based clinical practice guidelines (CPGs) in Traditional Chinese Medicine (TCM) using the Appraisal of Guidelines for Research and Evaluation (AG...Objective: To assess the quality of the first batch of Chinese evidence-based clinical practice guidelines (CPGs) in Traditional Chinese Medicine (TCM) using the Appraisal of Guidelines for Research and Evaluation (AGREE) instrument. Methods: Evidence-based CPGs in TCM supported by the World Health Organization Western Pacific Regional Office (WHO/WPRO) and whose development was organized by the China Academy of Chinese Medical Sciences were identified and manually retrieved. CPGs were assessed using the AGREE instrument, and the data in each CPG were analyzed in terms of the six domains in the AGREE instrument: scope and purpose, stakeholder involvement, rigor of development, clarity and presentation, applicability, and editorial independence. Results: Twenty-eight CPGs were identified, of which 26 were included in the study. The AGREE instrument rated the 26 CPGs in terms of the six domains. The assessment results showed the following average scores: for editorial independence, 84.16%; for rigor of development, 80.95%; for scope and purpose, 79.96%; for clarity and presentation, 70.88%; for stakeholder involvement, 61.28%; for applicability, the average score was only 27.09%. In summary, nine CPGs were rated as "strongly recommended", six as "recommended with provision or alternation", and 11 as "unsure". Conclusion: Most of the first batch of Chinese evidence-based CPGs in TCM had significant shortcomings in applicability. It is suggested that special attention be paid to enhancing the quality of applicability when developing evidence-based CPGs in TCM.展开更多
基金National 973 Project No.2002CB412507+5 种基金 National Natural Science Foundation of China No.90202002 Knowledge Innovation Project of IGSNRR CAS No.CXIOG-E01-02-04 One Hundred Talents Program of CAS.
文摘Combined with recent historical climate data and two periods of land use datasets from remote sensing data, we test the net primary productivity (NPP) data sets in North Chinamodelled by the satellite data-driven Global Production Efficiency Model (GLO-PEM) for detecting thewidespread spatial and temporal characteristics of the impacts of climate and land use change onthe regional NPP. Our results show that over the past 20 years, the mean annual temperature in thestudy region has remarkably increased by more than 0.064 ℃, but over the same period, there hasbeen a 1.49 mm decrease in annual precipitation and decrease in NPP by an annual rate of 6.9 TgC.The NPP changes in the study region were greatly affected by the average temperature andprecipitation by ten-day periods as well as the seasonal temperature and precipitation in the studyregion. The correlation between seasonal NPP and seasonal precipitation and temperature is highlyconsistent with land cover spatially, and the correlation coefficient changes with the changes ofvegetation types. The analysis reveals that the related areas in land use change only take up 5.45%of the whole studied region, so the climate changes dominate the impacts on the NPP in the wholestudy region (90% of the total). However, land use plays an absolute dominative role in areas withland cover changes, accounting for 97% of the total. From 1981 to 2000, the NPP in the whole studyregion remarkably reduced due to obvious precipitation decrease and temperature rise. Between twoperiods of land use (about 10 years), the changes in climate are predicted to promote a decrease inNPP by 78 ( + -0.6) TgC, and integrated impacts of climate changes and land use to promote adecrease in NPP by 87(+-0.8) TgC.
基金jointly supported by the National Natural Science Foundation in China (No.61601075)the Natural Science Foundation Project of CQ CSTC (No.cstc2016jcyj A0174)
文摘Constellations design for regional terrestrial-satellite network can strengthen the coverage for incomplete terrestrial cellular network. In this paper, a regional satellite constellation design scheme with multiple feature points and multiple optimization indicators is proposed by comprehensively considering multi-objective optimization and genetic algorithm, and "the Belt and Road" model is presented in the way of dividing over 70 nations into three regular target areas. Following this, we formulate the optimization model and devise a multi-objective genetic algorithm suited for the regional area with the coverage rate under simulating, computing and determining. Meanwhile, the total number of satellites in the constellation is reduced by calculating the ratio of actual coverage of a single-orbit constellation and the area of targets. Moreover, the constellations' performances of the proposed scheme are investigated with the connection of C++ and Satellite Tool Kit(STK). Simulation results show that the designed satellite constellations can achieve a good coverage of the target areas.
文摘In this paper, the major objective is to build a global dynamic network model to assess the global health condition .First use the PSR model and Analytic hierarchy process （AHP） to calculate the internal health status of some regions, and then establish a global network model which links each region together to figure out the global health status. Finally, taking the human influence into consideration, the degree of the earth＇s health can be figured out in a more accurate way.
基金The State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chi-nese Academy of Sciences, the open fund item (No. SKLLQG0701) to subsidizedthe constructprogram of the key discipline in Hunan Province, China, the fund item (No. D2007001) the State Key Labo-ratories of Continental Dynamics,Northwest University, the open fund item (No. DL2006001) to combine subsi-dized.
文摘Using earth satellite observation means, remote sensing information distilled technique and regional research production, we have roundly analyzed and made an integrated evaluation about the Lop Nur nuclear test field in western China. This product reveals the rarely-known nuke explosion effect and response events of geology conditions. It also offers us legible and practical first-hand materials about human extreme effects, important engineering environment and intimidating influence process. By excavating and appraising the materials gradually on the natural environment factors changing in the test field through macroscopic elimination and typical filtration, it can supply basic scientific data for security of national nuclear usage, appraising the nuclear environment synthetically and developing nuclear strategy expediently.
基金sponsored by the National Natural Science Foundation of China(Grant Nos.41020144004,41374019,41104022)the National High Technology Research and Development Program of China(Grant No.2013AA122501)
文摘BeiDou regional navigation satellite system （BDS） also called BeiDou-2 has been in full operation since December 27, 2012. It consists of 14 satellites, including 5 satellites in Geostationary Orbit （GEO）, 5 satellites in Inclined Geosynchronous Orbit （IGSO）, and 4 satellites in Medium Earth Orbit （MEO）. In this paper, its basic navigation and positioning performance are evaluated preliminarily by the real data collected in Beijing, including satellite visibility, Position Dilution of Precision （PDOP） value, the precision of code and carrier phase measurements, the accuracy of single point positioning and differential position- ing and ambiguity resolution （AR） performance, which are also compared with those of GPS. It is shown that the precision of BDS code and carrier phase measurements are about 33 cm and 2 mm, respectively, which are comparable to those of GPS, and the accuracy of BDS single point positioning has satisfied the design requirement. The real-time kinematic positioning is also feasible by BDS alolae in the opening condition, since its fixed rate and reliability of single-epoch dual-frequency AR is comparable to those of GPS. The accuracy of BDS carrier phase differential positioning is better than 1 cm for a very short baseline of 4.2 m and 3 cm for a short baseline of 8.2 km, which is on the same level with that of GPS. For the combined BDS and GPS, the fixed rate and reliability of single-epoch AR and the positioning accuracy are improved significantly. The accu- racy of BDS/GPS carrier phase differential positioning is about 35 and 20 % better than that of GPS for two short baseline tests in this study. The accuracy of BDS code differential positioning is better than 2.5 m. However it is worse than that of GPS, which may result from large code multipath errors of BDS GEO satellite measurements.
基金supported by the National High Technology Research and Development Program of China (863) (Grant Nos.2009Z12A324 and 2009AA12Z328)the National Natural Science Foundation of China (Grant Nos. 10703011, 11073047 and 11033004)the Science and Technology Commission of Shanghai (Grant No. 06DZ22101)
文摘Constellations of regional satellite navigation systems are usually constituted of geostationary satellites (GEO) and inclined geostationary satellites (IGSO) for better service availability. Analysis of real data shows that the pseudorange measurements of these two types of satellites contain significant multipath errors and code noise, and the multipath for GEO is extremely serious, which is harmful to system services. In contrast, multipath error of carrier phase measurements is less than 3 cm, which is smaller than the multipath of pseudorange measurements by two orders of magnitude. Using a particular combination of pseudorange and dual-frequency carrier phase measurements, the pseudorange multipath errors are detected, and their time varying features are analyzed. A real-time multipath correction algorithm is proposed in this paper, which is called CNMC (Code Noise and Multipath Correction). The algorithm decreases the influence of the multipath error and therefore ensures the performance of the system. Data processing experiments show that the multipath error level may be reduced from 0.5 m to 0.15 m by using this algorithm, and 60% of GEO multipath errors and 42% of IGSO multipath errors are successfully corrected with CNMC. Positioning experiments are performed with a constellation of 3 GEO plus 3 IGSO satellites. For dual-frequency users the East-West position accuracy is improved from 1.31 m to 0.94 m by using the CNMC algorithm, the South-North position accuracy is improved from 2.62 m to 2.29 m, and the vertical position accuracy is improved from 4.25 m to 3.05 m. After correcting multipath errors, the three-dimensional position accuracy is improved from 5.16 m to 3.94 m.
基金supported by National Natural Science Foundation of China(Grant Nos.4117412240890163&41031066)OPWSRP(Grant No.201005017)
文摘CHAMP satellite data and ground-based magnetic observations are used and combined to map the lithospheric magnetic field over China by means of the revised spherical cap harmonic analysis(R-SHCA)modeling technique.The magnetic field is described to a spatial resolution of 150 km at the mean Earth’s radius,which represents a good compromise between the resolutions afforded by surface and satellite data.We compare the magnetic anomalies modeled at the regional scale with composite regions containing large-scale of tectonic structures.These regions,including the Tarim Basin and the Tibetan Plateau,are correlated with regional magnetic anomalies at satellite altitude but contain a significant number of small-scale and complex magnetic structures at the mean Earth’s radius.These magnetic anomalies are globally consistent with the known geological features in China but also offer a way to delineate the contours of the geological blocks and to discuss the connection between magnetic anomalies and the heat flow distribution in this region.
文摘The short-pulse TDMA signal is an excellent solution to the near-far problem in the pseudolite augmentation systems,and the pulse duty cycle is an important element in the solution.This paper aims at designing the duty cycle of the pseudolite pulse signals with a theoretical method.At first,the scope of the duty cycle is derived theoretically with the object of ensuring the reception of both the pseudolite signals and the satellite signals,and the expression for the theoretical upper limit is given.Then based on the proposed expression,the duty cycles of Galileo pseudolite pulse signals are designed.The theoretical upper limit can guide the design of the short-pulse TDMA pseudolite signals.
基金supported by projects from the China Academy of Chinese Medical Sciences (No.Z0135)the State Administration of Traditional Chinese Medicine (No. ZYYS-2008)the National Science Foundation of China (No. 30825047)
文摘Objective: To assess the quality of the first batch of Chinese evidence-based clinical practice guidelines (CPGs) in Traditional Chinese Medicine (TCM) using the Appraisal of Guidelines for Research and Evaluation (AGREE) instrument. Methods: Evidence-based CPGs in TCM supported by the World Health Organization Western Pacific Regional Office (WHO/WPRO) and whose development was organized by the China Academy of Chinese Medical Sciences were identified and manually retrieved. CPGs were assessed using the AGREE instrument, and the data in each CPG were analyzed in terms of the six domains in the AGREE instrument: scope and purpose, stakeholder involvement, rigor of development, clarity and presentation, applicability, and editorial independence. Results: Twenty-eight CPGs were identified, of which 26 were included in the study. The AGREE instrument rated the 26 CPGs in terms of the six domains. The assessment results showed the following average scores: for editorial independence, 84.16%; for rigor of development, 80.95%; for scope and purpose, 79.96%; for clarity and presentation, 70.88%; for stakeholder involvement, 61.28%; for applicability, the average score was only 27.09%. In summary, nine CPGs were rated as "strongly recommended", six as "recommended with provision or alternation", and 11 as "unsure". Conclusion: Most of the first batch of Chinese evidence-based CPGs in TCM had significant shortcomings in applicability. It is suggested that special attention be paid to enhancing the quality of applicability when developing evidence-based CPGs in TCM.
