An overview of basic research on climate change in recent years in China is presented. In the past 100 years in China, average annual mean surface air temperature （SAT） has increased at a rate ranging from 0.03℃ （...An overview of basic research on climate change in recent years in China is presented. In the past 100 years in China, average annual mean surface air temperature （SAT） has increased at a rate ranging from 0.03℃ （10 yr）-1 to 0.12℃ （10 yr）-1. This warming is more evident in northern China and is more significant in winter and spring. In the past 50 years in China, at least 27% of the average annual warming has been caused by urbanization. Overall, no significant trends have been detected in annual and/or summer precipitation in China on a whole for the past 100 years or 50 years. Both increases and decreases in frequencies of major extreme climate events have been observed for the past 50 years. The frequencies of extreme temperature events have generally displayed a consistent pattern of change across the country, while the frequencies of extreme precipitation events have shown only regionally and seasonally significant trends. The frequency of tropical cyclone landfall decreased slightly, but the frequency of sand/dust storms decreased significantly. Proxy records indicate that the annual mean SAT in the past a few decades is the highest in the past 400-500 years in China, but it may not have exceeded the highest level of the Medieval Warm Period （1000 1300 AD）. Proxy records also indicate that droughts and floods in eastern China have been characterized by continuously abnormal rainfall periods, with the frequencies of extreme droughts and floods in the 20th century most likely being near the average levels of the past 2000 years. The attribution studies suggest that increasing greenhouse gas （GHG） concentrations in the atmosphere are likely to be a main factor for the observed surface warming nationwide. The Yangtze River and Huaihe River basins underwent a cooling trend in summer over the past 50 years, which might have been caused by increased aerosol concentrations and cloud cover. However, natural climate variability might have been a main driver for the mean and extreme precipitati展开更多
Inductively coupled plasma mass spectrometry （ICP-MS） is the most commonly used technique to deter- mine the abundances of trace elements in a wide range of geological materials. However, incomplete sample digestion...Inductively coupled plasma mass spectrometry （ICP-MS） is the most commonly used technique to deter- mine the abundances of trace elements in a wide range of geological materials. However, incomplete sample digestion, isobaric interferences and instrumental drift remain obvious problems that must be overcome in order to obtain precise and accurate results, For this reason, we have done many experi- ments and developed a set of simple, cost-effective and practical methods widely applicable for precise and rapid determination of trace element abundances in geological materials using ICP-MS. Commonly used high-pressure digestion technique is indeed effective in decomposing refractory phases, but this inevitably produces fluoride complexes that create new problems. We demonstrate that the fluoride complexes formed during high-pressure digestion can be readily re-dissolved using high-pressure vessel at 190 ℃ for only 2 h for 50 mg sample. In the case of isobaric interferences, although oxide （e.g., MO^＋/M^＋） and hydroxide （e.g., MO^＋/M^＋） productivity is variable between runs, the （MO^＋/M^＋）/（CeO^＋/Ce^＋） and （MOH^＋/M^＋）/（CeO^＋/Ce^＋） ratios remain constant, making isobaric interference correction for all other elements of interest straightforward, for which we provide an easy-to-use off-line procedure. We also show that mass-time-intensity drift curve is smooth as recognized previously, for which the correction can be readily done by analyzing a quality-control （QC） solution and using off-line Excel VBA procedure without internal standards. With these methods, we can produce data in reasonable agreement with rec- ommended values of international rock reference standards with a relative error of 〈8% and precision generally better than 5%. Importantly, compared to the widely used analytical practice, we can effectively save 〉60% of time （e.g., 〈24 h vs. 〉60 h）.展开更多
Array calibration with angularly dependent gain and phase uncertainties has long been a difficult problem. Although many array calibration methods have been reported extensively in the literature, they almost all assu...Array calibration with angularly dependent gain and phase uncertainties has long been a difficult problem. Although many array calibration methods have been reported extensively in the literature, they almost all assumed an angularly independent model for array uncertainties. Few calibration methods have been developed for the angularly dependent array uncertainties. A novel and efficient auto-calibration method for angularly dependent gain and phase uncertainties is proposed in this paper, which is called ISM (Instrumental Sensors Method). With the help of a few well-calibrated instrumental sensors, the ISM is able to achieve favorable and unambiguous direction-of-arrivals (DOAs) estimate and the corresponding angularly dependent gain and phase estimate simultaneously, even in the case of multiple non-disjoint sources. Since the mutual coupling and sensor position errors can all be described as angularly dependent gain/phase uncertainties, the ISM proposed still works in the presence of a combination of all these array perturbations. The ISM can be applied to arbitrary array geometries including linear arrays. The ISM is computationally efficient and requires only one-dimensional search, with no high-dimensional nonlinear search and convergence burden involved. Besides, no small error assumption is made, which is always an essential prerequisite for many existing array calibration techniques. The estimation performance of the ISM is analyzed theoretically and simulation results are provided to demonstrate the effectiveness and behavior of the proposed ISM.展开更多
Based on the analysis of the satellite DCB data estimated by our method and the Center for Orbit Determination in Europe(CODE)from 1999 to 2011,the features of the temporal variation of differential code biases(DCB)ar...Based on the analysis of the satellite DCB data estimated by our method and the Center for Orbit Determination in Europe(CODE)from 1999 to 2011,the features of the temporal variation of differential code biases(DCB)are studied.Summarily,there are three types of variations in DCB on different time scales.The first one is the day-to-day variation that exhibits more obviously in solar maximum years.The second one is the variation with about one year periodic variation that behaves more obviously from 1999 to 2004.The last one is the monotonously descending tendency from 1999 to 2010.Considering the basic ionospheric approximation in DCB estimation method,the features of the variability of the ionospheric morphology from 1999to 2010 are also displayed based on the ionospheric characteristic parameters.It can be concluded that the day-to-day and annual variation of the estimated global positioning system(GPS).DCB is related to the ionospheric variability.The variation of DCBs on solar cycle time scale includes the real hardware DCBs and pseudo-DCBs induced by ionospheric variation.No doubt,these kinds of"pseudo"variations of DCB will affect the precision of ionospheric total electron content(TEC)derived from the GPS data.In addition,this study is helpful for evaluating the influence of ionospheric weather on TEC derivation and is also useful for developing one estimation method of DCB with more stability and precision through introducing a more practical ionospheric model.展开更多
A new method for array calibration of array gain and phase uncertainties, which severely degrade the performance of spatial spectrum estimation, is presented. The method is based on the idea of the instrumental sensor...A new method for array calibration of array gain and phase uncertainties, which severely degrade the performance of spatial spectrum estimation, is presented. The method is based on the idea of the instrumental sensors method （ISM）, two well-calibrated sensors are added into the original array. By applying the principle of estimation of signal parameters via rotational invariance techniques （ESPRIT）, the direction-of-arrivals （DOAs） and uncertainties can be estimated simultaneously through eigen-decomposition. Compared with the conventional ones, this new method has less computational complexity while has higher estimation precision, what＇s more, it can overcome the problem of ambiguity. Both theoretical analysis and computer simulations show the effectiveness of the proposed method.展开更多
Due to the deficiencies in the conventional multiple-receiver localization syste,.ns based on direction of arrival （DOA） such as system complexity of interferometer or array and ampli- tude/phase unbalance between m...Due to the deficiencies in the conventional multiple-receiver localization syste,.ns based on direction of arrival （DOA） such as system complexity of interferometer or array and ampli- tude/phase unbalance between multiple receiving channels and constraint on antenna configuration, a new radiated source localization method using the changing rate of phase difference （CRPD） measured by a long baseline interferometer （LBI） only is studied. To solve the strictly nonlinear problem, a two-stage closed-form solution is proposed. In the first stage, the DOA and its changing rate are estimated from the CRPD of each observer by the pseudolinear least square （PLS） method, and then in the second stage, the source position and velocity are found by another PLS minimiza- tion. The bias of the algorithm caused by the correlation between the measurement matrix and the noise in the second stage is analyzed. To reduce this bias, an instrumental variable （IV） method is derived. A weighted IV estimator is given in order to reduce the estimation variance. The proposed method does not need any initial guess and the computation is small. The Cramer-Rao lower bound （CRLB） and mean square error （MSE） are also analyzed. Simulation results show that the proposed method can be close to the CRLB with moderate Gaussian measurement noise.展开更多
Foreign direct investment （FDI） in China is heavily concentrated in the coastal regions. Do inland provinces benefit from coastal FDI？ We use a provincial-level panel dataset and employ the fixed-effects instrument...Foreign direct investment （FDI） in China is heavily concentrated in the coastal regions. Do inland provinces benefit from coastal FDI？ We use a provincial-level panel dataset and employ the fixed-effects instrumental variables regression technique to investigate the interregional spillovers from coastal FDI to inland provinces. The study finds that, on average, coastal FDI has a negative impact on the economic growth of inlandprovinces. In addition, depending on the different trade activities engaged in （i.e. whether processing trade or ordinary trade）, coastal FDI has different impacts on the economic growth of inland provinces.展开更多
This paper investigates the impact of China＇s outward foreign direct investment （OFDI） on its economic growth. By using a provincial-level panel dataset and applying fixed- effects and instrumental variable regress...This paper investigates the impact of China＇s outward foreign direct investment （OFDI） on its economic growth. By using a provincial-level panel dataset and applying fixed- effects and instrumental variable regression techniques, the study finds that both OFDI from provincial firms and OFDI from state-owned enterprises have a positive impact on China＇s provincial economic growth. The positive impact of OFDI on provincial economic growth may be the result of reverse knowledge spillovers from OFDI to the home provincial economy through demonstration and imitation, labor movement, and backward and forward industrial linkages, thus increasing the productivity and the efficiency of home firms and promoting the growth of the home economy.展开更多
The authors analyzed the lead-lag connection of the Atlantic Multidecadal Oscillation (AMO) with East Asian surface air temperatures (EATs) using instrumental records, and compared the results with the Pacific Decadal...The authors analyzed the lead-lag connection of the Atlantic Multidecadal Oscillation (AMO) with East Asian surface air temperatures (EATs) using instrumental records, and compared the results with the Pacific Decadal Oscillation (PDO). The maximum correlation was found when EATs led the AMO by five to seven years (with a correlation coefficient of 0.72, whereas the correlation coefficient was 0.91 when the AMO led EATs by 24-28 years). This is different from the PDO, which mostly correlated with EATs when the PDO led EATs by 13-15 years (with a correlation coefficient of 0.67, whereas the correlation coefficient was 0.76 when EATs led the PDO by 24-26 years). The PDO led the AMO by 19-21 years (with a correlation coefficient of 0.71, whereas the correlation coefficient was 0.84 when the AMO led the PDO by 16-18 years). These results support a previous understanding that EATs positively correlate with the AMO, and imply that the observed East Asian warming trend may have been slowing down since the early 2010s.展开更多
The state-space representation of linear time-invariant (LTI) fractional order systems is introduced, and a proof of their stability theory is also given. Then an efficient identification algorithm is proposed for tho...The state-space representation of linear time-invariant (LTI) fractional order systems is introduced, and a proof of their stability theory is also given. Then an efficient identification algorithm is proposed for those fractional order systems. The basic idea of the algorithm is to compute fractional derivatives and the filter simultaneously, i.e., the filtered fractional derivatives can be obtained by computing them in one step, and then system identification can be fulfilled by the least square method. The instrumental variable method is also used in the identification of fractional order systems. In this way, even if there is colored noise in the systems, the unbiased estimation of the parameters can still be obtained. Finally an example of identifying a viscoelastic system is given to show the effectiveness of the aforementioned method.展开更多
Instead of establishing mathematical hydraulic system models from physical laws usually done with the problems of complex modelling processes, low reliability and practicality caused by large uncertainties, a novel mo...Instead of establishing mathematical hydraulic system models from physical laws usually done with the problems of complex modelling processes, low reliability and practicality caused by large uncertainties, a novel modelling method for a highly nonlinear system of a hydraulic excavator is presented. Based on the data collected in the excavator＇s arms driving experiments, a data-based excavator dynamic model using Simplified Refined Instrumental Variable （SRIV） identification and estimation algorithms is established. The validity of the proposed data-based model is indirectly demonstrated by the performance of computer simulation and the.real machine motion control exoeriments.展开更多
Background:Acute myeloid leukemia(AML)is a common type of hematological malignancy in elderly people.Geriatricians developed comprehensive geriatric assessment(CGA)methods for elderly patients;however,the tools used f...Background:Acute myeloid leukemia(AML)is a common type of hematological malignancy in elderly people.Geriatricians developed comprehensive geriatric assessment(CGA)methods for elderly patients;however,the tools used for CGA in AML are not uniform.Thus,we aimed to validate the instrumental activities of daily living(IADL)scales,age,comorbidities(Charlson Comorbidity Index),and albumin(IACA)index,which is a new tool for CGA,in elderly patients with AML.Methods:Patients aged>60 years who had been diagnosed with AML were screened for eligibility.Among the IACA low-,intermediate-,and high-risk groups,continuous variables were compared using the Mann-Whitney U test,and categorical variables were compared using/2 and Fisher exact tests.In addition,probabilities of overall survival(OS)were estimated using the Kaplan-Meier method.Results:A total of 21,34,and 6 patients were categorized into IACA low-risk(0 point),intermediate-risk(1-2 points),and high-risk(>3 points)groups,respectively.The rates of relapse/progression-related mortality were 23.8%,58.8%,and 100.0%in the IACA low-,intermediate-,and high-risk groups,respectively(χ^2=12.81,P<0.001).The 2-year probabilities of OS were 47.7%(95%confidence interval[CI]22.8%-72.6%)and 20.2%(95%CI 5.9%-34.5%)in the IACA low-and intermediate-risk groups,respectively(χ^2=5.99,P=0.014),which were significantly higher than those in the high-risk group(low-risk[47.7%(95%CI 22.8%-72.6%)]vs.high-risk[0],/=20.80,P<0.001;intermediate-risk[20.2%(95%CI 5.9%-34.5%)]vs.high-risk[0],χ^2=7.56,P=0.006;respectively).In the IACA low-risk group,the 2-year probability of OS in patients receiving induction chemotherapy(50.8%[95%CI 24.1%-77.5%])was significantly higher than that in those receiving best supportive care(0,χ^2=25.74,P<0.001).Conclusion:We suggest that the IACA index might be a simple and effective tool for comprehensive geriatric assessment in elderly AML patients.展开更多
This paper investigates the effect and transmission mechanism of air pollution on urbanization based on data from China’s 107 cities during 2005–2018.In order to identify the impact of air pollution on China’s urba...This paper investigates the effect and transmission mechanism of air pollution on urbanization based on data from China’s 107 cities during 2005–2018.In order to identify the impact of air pollution on China’s urbanization,we utilized night light data to represent the level of urbanization and used temperature inversion as an instrumental variable to mitigate endogeneity within the two-stage least squares framework.The results suggest that air pollution significantly slowed China’s urbanization process with economic growth acting as the transmission mechanism.The heterogeneity analyses revealed that air pollution had a greater negative impact on urbanization in northern regions than that in southern regions,and a greater negative impact in resource-oriented cities than that in non-resource-based cities.We also find that air pollution was to the detriment of urbanization in larger cities,which have more than 3 million residents,while it did not have a significant impact on Type II large cities,which have fewer than 3 million residents.展开更多
基金supported by the Ministry of Science and Technology of China (Grant Nos. 2007BAC29B02, 2007BAC03A01 and GYHY201206012)
文摘An overview of basic research on climate change in recent years in China is presented. In the past 100 years in China, average annual mean surface air temperature （SAT） has increased at a rate ranging from 0.03℃ （10 yr）-1 to 0.12℃ （10 yr）-1. This warming is more evident in northern China and is more significant in winter and spring. In the past 50 years in China, at least 27% of the average annual warming has been caused by urbanization. Overall, no significant trends have been detected in annual and/or summer precipitation in China on a whole for the past 100 years or 50 years. Both increases and decreases in frequencies of major extreme climate events have been observed for the past 50 years. The frequencies of extreme temperature events have generally displayed a consistent pattern of change across the country, while the frequencies of extreme precipitation events have shown only regionally and seasonally significant trends. The frequency of tropical cyclone landfall decreased slightly, but the frequency of sand/dust storms decreased significantly. Proxy records indicate that the annual mean SAT in the past a few decades is the highest in the past 400-500 years in China, but it may not have exceeded the highest level of the Medieval Warm Period （1000 1300 AD）. Proxy records also indicate that droughts and floods in eastern China have been characterized by continuously abnormal rainfall periods, with the frequencies of extreme droughts and floods in the 20th century most likely being near the average levels of the past 2000 years. The attribution studies suggest that increasing greenhouse gas （GHG） concentrations in the atmosphere are likely to be a main factor for the observed surface warming nationwide. The Yangtze River and Huaihe River basins underwent a cooling trend in summer over the past 50 years, which might have been caused by increased aerosol concentrations and cloud cover. However, natural climate variability might have been a main driver for the mean and extreme precipitati
基金supported by National Natural Science Foundation of China(41130314 and 41630968)Chinese Academy of Sciences Innovation Grant(Y42217101L)+1 种基金Qingdao National Laboratory for Marine Science and Technology(2015ASKJ03)Marine Geological Process and Environment(U1606401)
文摘Inductively coupled plasma mass spectrometry （ICP-MS） is the most commonly used technique to deter- mine the abundances of trace elements in a wide range of geological materials. However, incomplete sample digestion, isobaric interferences and instrumental drift remain obvious problems that must be overcome in order to obtain precise and accurate results, For this reason, we have done many experi- ments and developed a set of simple, cost-effective and practical methods widely applicable for precise and rapid determination of trace element abundances in geological materials using ICP-MS. Commonly used high-pressure digestion technique is indeed effective in decomposing refractory phases, but this inevitably produces fluoride complexes that create new problems. We demonstrate that the fluoride complexes formed during high-pressure digestion can be readily re-dissolved using high-pressure vessel at 190 ℃ for only 2 h for 50 mg sample. In the case of isobaric interferences, although oxide （e.g., MO^＋/M^＋） and hydroxide （e.g., MO^＋/M^＋） productivity is variable between runs, the （MO^＋/M^＋）/（CeO^＋/Ce^＋） and （MOH^＋/M^＋）/（CeO^＋/Ce^＋） ratios remain constant, making isobaric interference correction for all other elements of interest straightforward, for which we provide an easy-to-use off-line procedure. We also show that mass-time-intensity drift curve is smooth as recognized previously, for which the correction can be readily done by analyzing a quality-control （QC） solution and using off-line Excel VBA procedure without internal standards. With these methods, we can produce data in reasonable agreement with rec- ommended values of international rock reference standards with a relative error of 〈8% and precision generally better than 5%. Importantly, compared to the widely used analytical practice, we can effectively save 〉60% of time （e.g., 〈24 h vs. 〉60 h）.
文摘Array calibration with angularly dependent gain and phase uncertainties has long been a difficult problem. Although many array calibration methods have been reported extensively in the literature, they almost all assumed an angularly independent model for array uncertainties. Few calibration methods have been developed for the angularly dependent array uncertainties. A novel and efficient auto-calibration method for angularly dependent gain and phase uncertainties is proposed in this paper, which is called ISM (Instrumental Sensors Method). With the help of a few well-calibrated instrumental sensors, the ISM is able to achieve favorable and unambiguous direction-of-arrivals (DOAs) estimate and the corresponding angularly dependent gain and phase estimate simultaneously, even in the case of multiple non-disjoint sources. Since the mutual coupling and sensor position errors can all be described as angularly dependent gain/phase uncertainties, the ISM proposed still works in the presence of a combination of all these array perturbations. The ISM can be applied to arbitrary array geometries including linear arrays. The ISM is computationally efficient and requires only one-dimensional search, with no high-dimensional nonlinear search and convergence burden involved. Besides, no small error assumption is made, which is always an essential prerequisite for many existing array calibration techniques. The estimation performance of the ISM is analyzed theoretically and simulation results are provided to demonstrate the effectiveness and behavior of the proposed ISM.
基金supported by the National Natural Science Foundation of China(41274156 and 41174134)National Important Basic Research Project of China(Grant No.2011CB811405)
文摘Based on the analysis of the satellite DCB data estimated by our method and the Center for Orbit Determination in Europe(CODE)from 1999 to 2011,the features of the temporal variation of differential code biases(DCB)are studied.Summarily,there are three types of variations in DCB on different time scales.The first one is the day-to-day variation that exhibits more obviously in solar maximum years.The second one is the variation with about one year periodic variation that behaves more obviously from 1999 to 2004.The last one is the monotonously descending tendency from 1999 to 2010.Considering the basic ionospheric approximation in DCB estimation method,the features of the variability of the ionospheric morphology from 1999to 2010 are also displayed based on the ionospheric characteristic parameters.It can be concluded that the day-to-day and annual variation of the estimated global positioning system(GPS).DCB is related to the ionospheric variability.The variation of DCBs on solar cycle time scale includes the real hardware DCBs and pseudo-DCBs induced by ionospheric variation.No doubt,these kinds of"pseudo"variations of DCB will affect the precision of ionospheric total electron content(TEC)derived from the GPS data.In addition,this study is helpful for evaluating the influence of ionospheric weather on TEC derivation and is also useful for developing one estimation method of DCB with more stability and precision through introducing a more practical ionospheric model.
文摘A new method for array calibration of array gain and phase uncertainties, which severely degrade the performance of spatial spectrum estimation, is presented. The method is based on the idea of the instrumental sensors method （ISM）, two well-calibrated sensors are added into the original array. By applying the principle of estimation of signal parameters via rotational invariance techniques （ESPRIT）, the direction-of-arrivals （DOAs） and uncertainties can be estimated simultaneously through eigen-decomposition. Compared with the conventional ones, this new method has less computational complexity while has higher estimation precision, what＇s more, it can overcome the problem of ambiguity. Both theoretical analysis and computer simulations show the effectiveness of the proposed method.
基金co-supported by the Foundation of National Defense Key Laboratory of China (No. 9140C860304)the National High Technology Research and Development Program of China (No. 2011AA7072048)
文摘Due to the deficiencies in the conventional multiple-receiver localization syste,.ns based on direction of arrival （DOA） such as system complexity of interferometer or array and ampli- tude/phase unbalance between multiple receiving channels and constraint on antenna configuration, a new radiated source localization method using the changing rate of phase difference （CRPD） measured by a long baseline interferometer （LBI） only is studied. To solve the strictly nonlinear problem, a two-stage closed-form solution is proposed. In the first stage, the DOA and its changing rate are estimated from the CRPD of each observer by the pseudolinear least square （PLS） method, and then in the second stage, the source position and velocity are found by another PLS minimiza- tion. The bias of the algorithm caused by the correlation between the measurement matrix and the noise in the second stage is analyzed. To reduce this bias, an instrumental variable （IV） method is derived. A weighted IV estimator is given in order to reduce the estimation variance. The proposed method does not need any initial guess and the computation is small. The Cramer-Rao lower bound （CRLB） and mean square error （MSE） are also analyzed. Simulation results show that the proposed method can be close to the CRLB with moderate Gaussian measurement noise.
文摘Foreign direct investment （FDI） in China is heavily concentrated in the coastal regions. Do inland provinces benefit from coastal FDI？ We use a provincial-level panel dataset and employ the fixed-effects instrumental variables regression technique to investigate the interregional spillovers from coastal FDI to inland provinces. The study finds that, on average, coastal FDI has a negative impact on the economic growth of inlandprovinces. In addition, depending on the different trade activities engaged in （i.e. whether processing trade or ordinary trade）, coastal FDI has different impacts on the economic growth of inland provinces.
文摘This paper investigates the impact of China＇s outward foreign direct investment （OFDI） on its economic growth. By using a provincial-level panel dataset and applying fixed- effects and instrumental variable regression techniques, the study finds that both OFDI from provincial firms and OFDI from state-owned enterprises have a positive impact on China＇s provincial economic growth. The positive impact of OFDI on provincial economic growth may be the result of reverse knowledge spillovers from OFDI to the home provincial economy through demonstration and imitation, labor movement, and backward and forward industrial linkages, thus increasing the productivity and the efficiency of home firms and promoting the growth of the home economy.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA05090406)the special projects of China Meteorological Administration(Grant No.GYHY201006022)
文摘The authors analyzed the lead-lag connection of the Atlantic Multidecadal Oscillation (AMO) with East Asian surface air temperatures (EATs) using instrumental records, and compared the results with the Pacific Decadal Oscillation (PDO). The maximum correlation was found when EATs led the AMO by five to seven years (with a correlation coefficient of 0.72, whereas the correlation coefficient was 0.91 when the AMO led EATs by 24-28 years). This is different from the PDO, which mostly correlated with EATs when the PDO led EATs by 13-15 years (with a correlation coefficient of 0.67, whereas the correlation coefficient was 0.76 when EATs led the PDO by 24-26 years). The PDO led the AMO by 19-21 years (with a correlation coefficient of 0.71, whereas the correlation coefficient was 0.84 when the AMO led the PDO by 16-18 years). These results support a previous understanding that EATs positively correlate with the AMO, and imply that the observed East Asian warming trend may have been slowing down since the early 2010s.
文摘The state-space representation of linear time-invariant (LTI) fractional order systems is introduced, and a proof of their stability theory is also given. Then an efficient identification algorithm is proposed for those fractional order systems. The basic idea of the algorithm is to compute fractional derivatives and the filter simultaneously, i.e., the filtered fractional derivatives can be obtained by computing them in one step, and then system identification can be fulfilled by the least square method. The instrumental variable method is also used in the identification of fractional order systems. In this way, even if there is colored noise in the systems, the unbiased estimation of the parameters can still be obtained. Finally an example of identifying a viscoelastic system is given to show the effectiveness of the aforementioned method.
文摘Instead of establishing mathematical hydraulic system models from physical laws usually done with the problems of complex modelling processes, low reliability and practicality caused by large uncertainties, a novel modelling method for a highly nonlinear system of a hydraulic excavator is presented. Based on the data collected in the excavator＇s arms driving experiments, a data-based excavator dynamic model using Simplified Refined Instrumental Variable （SRIV） identification and estimation algorithms is established. The validity of the proposed data-based model is indirectly demonstrated by the performance of computer simulation and the.real machine motion control exoeriments.
基金This work was supported by grants from the Beijing Committee of Science and Technology(No.Z181100001718162,No.Z171100001017200,and No.Z171100001017084)the Capital's Funds for Health Improvement and Research(No.2018-4-4089).
文摘Background:Acute myeloid leukemia(AML)is a common type of hematological malignancy in elderly people.Geriatricians developed comprehensive geriatric assessment(CGA)methods for elderly patients;however,the tools used for CGA in AML are not uniform.Thus,we aimed to validate the instrumental activities of daily living(IADL)scales,age,comorbidities(Charlson Comorbidity Index),and albumin(IACA)index,which is a new tool for CGA,in elderly patients with AML.Methods:Patients aged>60 years who had been diagnosed with AML were screened for eligibility.Among the IACA low-,intermediate-,and high-risk groups,continuous variables were compared using the Mann-Whitney U test,and categorical variables were compared using/2 and Fisher exact tests.In addition,probabilities of overall survival(OS)were estimated using the Kaplan-Meier method.Results:A total of 21,34,and 6 patients were categorized into IACA low-risk(0 point),intermediate-risk(1-2 points),and high-risk(>3 points)groups,respectively.The rates of relapse/progression-related mortality were 23.8%,58.8%,and 100.0%in the IACA low-,intermediate-,and high-risk groups,respectively(χ^2=12.81,P<0.001).The 2-year probabilities of OS were 47.7%(95%confidence interval[CI]22.8%-72.6%)and 20.2%(95%CI 5.9%-34.5%)in the IACA low-and intermediate-risk groups,respectively(χ^2=5.99,P=0.014),which were significantly higher than those in the high-risk group(low-risk[47.7%(95%CI 22.8%-72.6%)]vs.high-risk[0],/=20.80,P<0.001;intermediate-risk[20.2%(95%CI 5.9%-34.5%)]vs.high-risk[0],χ^2=7.56,P=0.006;respectively).In the IACA low-risk group,the 2-year probability of OS in patients receiving induction chemotherapy(50.8%[95%CI 24.1%-77.5%])was significantly higher than that in those receiving best supportive care(0,χ^2=25.74,P<0.001).Conclusion:We suggest that the IACA index might be a simple and effective tool for comprehensive geriatric assessment in elderly AML patients.
基金supported by Preliminary Funding Project of Hubei Provincial Department of Education[Grant No.22ZD100].
文摘This paper investigates the effect and transmission mechanism of air pollution on urbanization based on data from China’s 107 cities during 2005–2018.In order to identify the impact of air pollution on China’s urbanization,we utilized night light data to represent the level of urbanization and used temperature inversion as an instrumental variable to mitigate endogeneity within the two-stage least squares framework.The results suggest that air pollution significantly slowed China’s urbanization process with economic growth acting as the transmission mechanism.The heterogeneity analyses revealed that air pollution had a greater negative impact on urbanization in northern regions than that in southern regions,and a greater negative impact in resource-oriented cities than that in non-resource-based cities.We also find that air pollution was to the detriment of urbanization in larger cities,which have more than 3 million residents,while it did not have a significant impact on Type II large cities,which have fewer than 3 million residents.
