Lunar optical polarization is a fascinating phenomenon that occurs when sunlight reflects off the surface of the Moon and becomes polarized.This study employs a novel split-focus plane polarimetric camera to conduct t...Lunar optical polarization is a fascinating phenomenon that occurs when sunlight reflects off the surface of the Moon and becomes polarized.This study employs a novel split-focus plane polarimetric camera to conduct the initial white light polarimetric observations on the near side of the Moon.We obtained the linear degree of polarization(DOP)parameters of white light by observation from the eastern and western hemispheres of the Moon.The findings indicate that the white light polarization is lower in the lunar highland than in the lunar maria overall.Combining the analysis of lunar soil samples,we noticed and determined that the DOP parameters of white light demonstrate high consistency with iron oxide on the Moon.This study may serve as a new diagnostic tool for the Moon.展开更多
With great advance of ground-based extensive air shower arrays,such as LHAASO and HAWC,many very high energy(VHE)gamma-ray sources have been discovered and are being monitored regardless of the day and the night.Hence...With great advance of ground-based extensive air shower arrays,such as LHAASO and HAWC,many very high energy(VHE)gamma-ray sources have been discovered and are being monitored regardless of the day and the night.Hence,the Sun and Moon would have some impacts on the observation of gamma-ray sources,which have not been taken into account in previous analysis.In this paper,the influence of the Sun and Moon on the observation of very high energy gamma-ray sources when they are near the line of sight of the Sun or Moon is estimated.The tracks of all the known VHE sources are scanned and several VHE sources are found to be very close to the line of sight of the Sun or Moon during some period.The absorption of very high energy gamma rays by sunlight is estimated with detailed method and some useful conclusions are achieved.The main influence is the block of the Sun and Moon on gamma rays and the shadow on the cosmic ray background.The influence is investigated considering the detector angular resolution and some strategies on data analysis are proposed to avoid the underestimation of the gamma-ray emission.展开更多
In this paper,the mission and the thermal environment of the Solar Close Observations and Proximity Experiments(SCOPE)spacecraft are analyzed,and an advanced thermal management system(ATMS)is designed for it.The relat...In this paper,the mission and the thermal environment of the Solar Close Observations and Proximity Experiments(SCOPE)spacecraft are analyzed,and an advanced thermal management system(ATMS)is designed for it.The relationship and functions of the integrated database,the intelligent thermal control system and the efficient liquid cooling system in the ATMS are elaborated upon.For the complex thermal field regulation system and extreme space thermal environment,a modular simulation and thermal field planning method are proposed,and the feasibility of the planning algorithm is verified by numerical simulation.A solar array liquid cooling system is developed,and the system simulation results indicate that the temperatures of the solar arrays meet the requirements as the spacecraft flies by perihelion and aphelion.The advanced thermal management study supports the development of the SCOPE program and provides a reference for the thermal management in other deep-space exploration programs.展开更多
Objective: To study the treatment of B-Thalas-semia (ThE) with Chinese herbal medicine for Bushen Yisui (BSYS), its theoretical base and molecular mechanism. Methods: Seventy-eight patients with ThE were treated with ...Objective: To study the treatment of B-Thalas-semia (ThE) with Chinese herbal medicine for Bushen Yisui (BSYS), its theoretical base and molecular mechanism. Methods: Seventy-eight patients with ThE were treated with BSYS recipe (consisted of 11 Chinese herbal drugs as Dogwood fruit, Fleeceflower root, prepared Rehmannia root and turtle shell, etc.) orally taken, 3 times per day, 10 g/time, 3 months as one therapeutic course. Hemoglobin (Hb), red blood cell (RBC), reticulocyte (Ret) and hemoglobin F (HbF) were checked every month. At the same time, PAGE, PVR, PCR-SSCP, RT-PCR, DNA series analysis, mRNA gene expression analysis techniques were used to conduct the systematic gene analysis in patients to study the molecular mechanism of TCM treatment from aspects of gene mutation, gene expression and control-regulation. Results: All the blood criteria in patients after BSYS treatment were improved significantly with clinical symptoms展开更多
This paper systematically summarizes previous measuring methods and observational instruments for the magnitude of dewfall on land surface, analyzes the characteristics of common observational instruments for land sur...This paper systematically summarizes previous measuring methods and observational instruments for the magnitude of dewfall on land surface, analyzes the characteristics of common observational instruments for land surface dewfall, and describes several basic dewfall measurement methods. Moreover, the basic principles of these methods and instruments are interpreted, and their advantages, disadvantages, and applicability are analyzed. Recommendations for the further improvement of these observational instruments and the development of dewfall measuring methods are presented, and new technologies and scientific proposals for exploiting dewfall are elucidated.展开更多
Atmospheric ammonia(NH_(3)) is a chemically active trace gas that plays an important role in the atmospheric environment and climate change. Satellite remote sensing is a powerful technique to monitor NH_(3) concentra...Atmospheric ammonia(NH_(3)) is a chemically active trace gas that plays an important role in the atmospheric environment and climate change. Satellite remote sensing is a powerful technique to monitor NH_(3) concentration based on the absorption lines of NH_(3) in the thermal infrared region. In this study, we establish a retrieval algorithm to derive the NH_(3)column from the Hyperspectral Infrared Atmospheric Sounder(HIRAS) onboard the Chinese Feng Yun(FY)-3D satellite and present the first atmospheric NH_(3) column global map observed by the HIRAS instrument. The HIRAS observations can well capture NH_(3) hotspots around the world, e.g., India, West Africa, and East China, where large NH_(3) emissions exist. The HIRAS NH_(3) columns are also compared to the space-based Infrared Atmospheric Sounding Interferometer(IASI)measurements, and we find that the two instruments observe a consistent NH_(3) global distribution, with correlation coefficient(R) values of 0.28–0.73. Finally, some remaining issues about the HIRAS NH_(3) retrieval are discussed.展开更多
Wavelet transform method is applied to measure time-frequency distribution characteristics of digital deformation data and noise. Based on the characteristics of primary modulus and stochastic white noise discriminati...Wavelet transform method is applied to measure time-frequency distribution characteristics of digital deformation data and noise. Based on the characteristics of primary modulus and stochastic white noise discrimination factor of wavelet decomposition, we analyze the variation rule of normal background and noise data from Shandong digital deformation observation data. The research results indicate that: a) 1/4 daily wave, semi-diurnal tide wave, daily wave and half lunar wave and so on quasi-periodic signal exist in the detail decomposing signal of wavelet when scale are equal to 2, 3 and 4; b) The amplitude of detail decomposing signal is the biggest when scale is equal to 3; c) The detail decomposing signal contains mainly noise corresponding to scale 1 and 5, respectively; d) We may trace the abnormal precursory which is related to earthquake by analyzing non-earthquake wavelet decomposing signal whose scale is specified from digital deformation observation data.展开更多
By employing the previous Voronoi approach and replacing its nearest neighbor approx- imation with Drizzle in iterative signal extraction, we develop a fast iterative Drizzle algorithm, namedfiDrizzle, to reconstruct ...By employing the previous Voronoi approach and replacing its nearest neighbor approx- imation with Drizzle in iterative signal extraction, we develop a fast iterative Drizzle algorithm, namedfiDrizzle, to reconstruct the underlying band-limited image from undersampled dithered frames. Compared with the existing iDrizzle, the new algorithm improves rate of convergence and accelerates the computational speed. Moreover, under the same conditions (e.g. the same number of dithers and iterations), fiDrizzle can make a better quality reconstruction than iDrizzle, due to the newly discov- ered High Sampling caused Decelerating Convergence (HSDC) effect in the iterative signal extraction process.fiDrizzle demonstrates its powerful ability to perform image deconvolution from undersampled dithers.展开更多
OBJECTIVE: To compare the clinical effect of brachial plexus block with "One Injection Two Points" guided under ultrasound and the conventional method guiding by ultrasound. METHODS: 70 patients were randomi...OBJECTIVE: To compare the clinical effect of brachial plexus block with "One Injection Two Points" guided under ultrasound and the conventional method guiding by ultrasound. METHODS: 70 patients were randomized evenly into 2 groups, with 35 patients in each group, while the Experiment Group(Group B) received One Injection Two Points" method, the Control Group(Group A) received the conventional method.The nerve block every 5 s, the success rate of anesthesia, the dosage of local anesthetics, second remedial anesthesia, adverse reactions, etc.were recorded. RESULTS: Group B was superior to group A in the success rate of anesthesia; There were 6 patients in group A who required constant pump injection of Remifentanil to remedy, while no patients in Group B needed remedy treatment. There were no serious adverse reactions in both groups.CONCLUSIONS: The clinical effect of brachial plexus block with "One Injection Two Points" method guided under ultrasoundguiding by ultrasound was superior to that of the conventional method.展开更多
We study the least squares estimation of drift parameters for a class of stochastic differential equations driven by small a-stable noises, observed at n regularly spaced time points ti = i/n, i = 1,...,n on [0, 1]. U...We study the least squares estimation of drift parameters for a class of stochastic differential equations driven by small a-stable noises, observed at n regularly spaced time points ti = i/n, i = 1,...,n on [0, 1]. Under some regularity conditions, we obtain the consistency and the rate of convergence of the least squares estimator (LSE) when a small dispersion parameter ε→0 and n →∞ simultaneously. The asymptotic distribution of the LSE in our setting is shown to be stable, which is completely different from the classical cases where asymptotic distributions are normal.展开更多
The solar radio signal that can be received by the ground-based telescopes covers a wide frequency range,allowing us to monitor the complex physical processes occurred from the solar surface to the vast interplanetary...The solar radio signal that can be received by the ground-based telescopes covers a wide frequency range,allowing us to monitor the complex physical processes occurred from the solar surface to the vast interplanetary space.MingantU SpEctral Radioheliograph(MUSER),as the latest generation of solar dedicated radio spectral-imaging instrument in the centimeter-decimeter wavelengths,has accumulated a large number of observational data since its commissioning observation in 2014.This paper presents the main observational results identified by MUSER from 2014 to 2019,including the quiet Sun and 94 solar radio burst events.We find that there are 81 events accompanied with Geostationary Operational Environmental Satellites(GOES)soft X-ray(SXR)flares,among which the smallest flare class is B1.0.There are 13 events without accompanying any recorded flares,among which the smallest SXR intensity during the radio burst period is equivalent to level-A.The main characteristics of all radio burst events are presented,which shows the powerful ability of MUSER to capture the valuable information of the solar non-thermal processes and the importance for space weather.This work also provides a database for further in-depth research.展开更多
The Fourier transform spectrometer(FTS)is a core instrument for solar observation with high spectral resolution,especially in the infrared.The Infrared System for the Accurate Measurement of Solar Magnetic Field(AIMS)...The Fourier transform spectrometer(FTS)is a core instrument for solar observation with high spectral resolution,especially in the infrared.The Infrared System for the Accurate Measurement of Solar Magnetic Field(AIMS),working at 10-13μm,will use an FTS to observe the solar spectrum.The Bruker IFS-125 HR,which meets the spectral resolution requirement of AIMS but simply equips with a point source detector,is employed to carry out preliminary experiment for AIMS.A sun-light feeding experimental system is further developed.Several experiments are taken with them during 2018 and 2019 to observe the solar spectrum in the visible and near infrared wavelength,respectively.We also proposed an inversion method to retrieve the solar spectrum from the observed interferogram and compared it with the standard solar spectrum atlas.Although there is a wavelength limitation due to the present sun-light feeding system,the results in the wavelength band from 0.45-1.0μm and 1.0-2.2μm show a good consistency with the solar spectrum atlas,indicating the validity of our observing configuration,the data analysis method and the potential to work in longer wavelength.The work provided valuable experience for the AIMS not only for the operation of an FTS but also for the development of its scientific data processing software.展开更多
Often in longitudinal studies, some subjects complete their follow-up visits, but others miss their visits due to various reasons. For those who miss follow-up visits, some of them might learn that the event of intere...Often in longitudinal studies, some subjects complete their follow-up visits, but others miss their visits due to various reasons. For those who miss follow-up visits, some of them might learn that the event of interest has already happened when they come back. In this case, not only are their event times interval-censored, but also their time-dependent measurements are incomplete. This problem was motivated by a national longitudinal survey of youth data. Maximum likelihood estimation (MLE) method based on expectation-maximization (EM) algorithm is used for parameter estimation. Then missing information principle is applied to estimate the variance-covariance matrix of the MLEs. Simulation studies demonstrate that the proposed method works well in terms of bias, standard error, and power for samples of moderate size. The national longitudinal survey of youth 1997 (NLSY97) data is analyzed for illustration.展开更多
The Zhoubi Suanjing, one of the most important ancient Chinese books on mathematical astronomy, was compiled about 100 BC in the Western Han dynasty (BC 206 - AD 23). We study the gnomon shadow lengths for the 24 so...The Zhoubi Suanjing, one of the most important ancient Chinese books on mathematical astronomy, was compiled about 100 BC in the Western Han dynasty (BC 206 - AD 23). We study the gnomon shadow lengths for the 24 solar terms as recorded in the book. Special attention is paid to the so-called law of ‘cun qian li’, which says the shadow length of a gnomon of 8 chi (about 1.96 m) high will increase (or decrease) 1 cun (1/10chi) for every 10001i (roughly 400kin) the gnomon moves northward (or south- ward). From these data, one can derive the time and location of the observations. The resuits, however, do not fit historical facts. We suggest that compilers of the Zhoubi Suanjing must have modified the original data according to the law of ‘cun qian li’. Through reversing the situation, we recovered the original data, our analysis of which reveals the best possible observation time as 564 BC and the location of observation as 35.78° N latitude. We conclude that this must be the earliest records of solar meridian observations in China. In the meantime, we give the errors of solar altitudes for the 24 solar terms. The average deviation is 5.22°, and the mean absolute deviation is 5.52°, signifying the accuracy of astronomical calculations from that time.展开更多
With the rapid development of China s economic construction and the rapid advancement of urban-rural integration construction, meteorological detection environment has been damaged repeatedly, which seriously affects ...With the rapid development of China s economic construction and the rapid advancement of urban-rural integration construction, meteorological detection environment has been damaged repeatedly, which seriously affects the representativeness, accuracy, and comparability of meteorological data, so it is urgent to protect meteorological detection environment. Based on the investigation and evaluation method of detection environment of national ground meteorological observation stations and high-altitude meteorological observation stations, satellite remote sensing data, and climate analysis method, the evaluation method of detection environment and meteorological data was improved to comprehensively assess the detection environment and meteorological data of stations. After the evaluation results were compared with the results of the survey and evaluation in 2013, it is found that the new assessment method maintains the continuity of detection environment assessment and can objectively reflect the changes of the station detection environment. The research on the method and standard for the evaluation of detection environment and data analysis of meteorological stations provides a scientific basis for the establishment of detection environmental protection plans by stations at all levels, and provides technical support for the scientific and rational adjustment of station network by administrative departments at all levels.展开更多
The quasar PKSO528+134 was observed to flare by the energetic gamma-ray experiment(EGR-ET)γ-ray telescope on the Compton gamma-ray observatory during the viewing period 213(VP213).The Compton telescope data from VP21...The quasar PKSO528+134 was observed to flare by the energetic gamma-ray experiment(EGR-ET)γ-ray telescope on the Compton gamma-ray observatory during the viewing period 213(VP213).The Compton telescope data from VP213 have been reanalyzed by using the direct demodulation method.Images of the source are obtained at energies above 3 MeV and the time variability in the energy range 10-30 MeV is consistent with the result of EGRET.There is no spectral break at energies above 3 MeV during the flare.展开更多
Data of traffic flow, speed and density are required for planning, designing, and modelling of traffic stream for all parts of the road system. Specialized equipments such as stationary counts are used to record volum...Data of traffic flow, speed and density are required for planning, designing, and modelling of traffic stream for all parts of the road system. Specialized equipments such as stationary counts are used to record volume and speed;but they are expensive, difficult to set up, and require periodic maintenance. The moving observer method was proposed in 1954 by Wardrop and Charlesworth to estimate these variables inexpensively. Basically, the observer counts the number of vehicles overtaken, the number of vehicles passed, and the number of vehicles encountered while traveling in the opposite direction. The trip time is reported for both travel directions. Additionally, the length of road segment is measured. These variables are then used in estimating speeds and volumes. In a westbound direction from Interstate Highway 30 (I-30) in the DFW area, this study examined the accuracy and feasibility of this method by comparing it with stationary observer method as the standard method for such counts. The statistical tests were used to test the accuracy. Results show that this method provides accurate volume and speed estimates when compared to the stationary method for the road segment with three lanes per direction, especially when several runs are taken.展开更多
基金supported by the National Key Research and Development Program of China(2021YFA0715101)partly supported by a National LLR station project+2 种基金the National Natural Science Foundation of China(NSFC,Grant Nos.11973064 and 42101413)Jilin Province Mid-youth science and technology innovation and entrepreneurship outstanding talent project(20220508147RC)the Changchun City and Chinese Academy of Sciences Science and Technology Cooperation High-tech Industrialization Special Fund Project(21SH05)。
文摘Lunar optical polarization is a fascinating phenomenon that occurs when sunlight reflects off the surface of the Moon and becomes polarized.This study employs a novel split-focus plane polarimetric camera to conduct the initial white light polarimetric observations on the near side of the Moon.We obtained the linear degree of polarization(DOP)parameters of white light by observation from the eastern and western hemispheres of the Moon.The findings indicate that the white light polarization is lower in the lunar highland than in the lunar maria overall.Combining the analysis of lunar soil samples,we noticed and determined that the DOP parameters of white light demonstrate high consistency with iron oxide on the Moon.This study may serve as a new diagnostic tool for the Moon.
基金supported by the National Natural Science Foundation of China under grant Nos.12393854,12022502 and 12263007by the High-level Talent Support program of Yunnan Province。
文摘With great advance of ground-based extensive air shower arrays,such as LHAASO and HAWC,many very high energy(VHE)gamma-ray sources have been discovered and are being monitored regardless of the day and the night.Hence,the Sun and Moon would have some impacts on the observation of gamma-ray sources,which have not been taken into account in previous analysis.In this paper,the influence of the Sun and Moon on the observation of very high energy gamma-ray sources when they are near the line of sight of the Sun or Moon is estimated.The tracks of all the known VHE sources are scanned and several VHE sources are found to be very close to the line of sight of the Sun or Moon during some period.The absorption of very high energy gamma rays by sunlight is estimated with detailed method and some useful conclusions are achieved.The main influence is the block of the Sun and Moon on gamma rays and the shadow on the cosmic ray background.The influence is investigated considering the detector angular resolution and some strategies on data analysis are proposed to avoid the underestimation of the gamma-ray emission.
文摘In this paper,the mission and the thermal environment of the Solar Close Observations and Proximity Experiments(SCOPE)spacecraft are analyzed,and an advanced thermal management system(ATMS)is designed for it.The relationship and functions of the integrated database,the intelligent thermal control system and the efficient liquid cooling system in the ATMS are elaborated upon.For the complex thermal field regulation system and extreme space thermal environment,a modular simulation and thermal field planning method are proposed,and the feasibility of the planning algorithm is verified by numerical simulation.A solar array liquid cooling system is developed,and the system simulation results indicate that the temperatures of the solar arrays meet the requirements as the spacecraft flies by perihelion and aphelion.The advanced thermal management study supports the development of the SCOPE program and provides a reference for the thermal management in other deep-space exploration programs.
文摘Objective: To study the treatment of B-Thalas-semia (ThE) with Chinese herbal medicine for Bushen Yisui (BSYS), its theoretical base and molecular mechanism. Methods: Seventy-eight patients with ThE were treated with BSYS recipe (consisted of 11 Chinese herbal drugs as Dogwood fruit, Fleeceflower root, prepared Rehmannia root and turtle shell, etc.) orally taken, 3 times per day, 10 g/time, 3 months as one therapeutic course. Hemoglobin (Hb), red blood cell (RBC), reticulocyte (Ret) and hemoglobin F (HbF) were checked every month. At the same time, PAGE, PVR, PCR-SSCP, RT-PCR, DNA series analysis, mRNA gene expression analysis techniques were used to conduct the systematic gene analysis in patients to study the molecular mechanism of TCM treatment from aspects of gene mutation, gene expression and control-regulation. Results: All the blood criteria in patients after BSYS treatment were improved significantly with clinical symptoms
基金supported by the National Science Foundation of China (Grant Nos. 40830957 and 40575006)
文摘This paper systematically summarizes previous measuring methods and observational instruments for the magnitude of dewfall on land surface, analyzes the characteristics of common observational instruments for land surface dewfall, and describes several basic dewfall measurement methods. Moreover, the basic principles of these methods and instruments are interpreted, and their advantages, disadvantages, and applicability are analyzed. Recommendations for the further improvement of these observational instruments and the development of dewfall measuring methods are presented, and new technologies and scientific proposals for exploiting dewfall are elucidated.
基金supported by the Feng Yun Application Pioneering Project (FY-APP-2022.0502)the National Natural Science Foundation of China (Grant No. 42205140)。
文摘Atmospheric ammonia(NH_(3)) is a chemically active trace gas that plays an important role in the atmospheric environment and climate change. Satellite remote sensing is a powerful technique to monitor NH_(3) concentration based on the absorption lines of NH_(3) in the thermal infrared region. In this study, we establish a retrieval algorithm to derive the NH_(3)column from the Hyperspectral Infrared Atmospheric Sounder(HIRAS) onboard the Chinese Feng Yun(FY)-3D satellite and present the first atmospheric NH_(3) column global map observed by the HIRAS instrument. The HIRAS observations can well capture NH_(3) hotspots around the world, e.g., India, West Africa, and East China, where large NH_(3) emissions exist. The HIRAS NH_(3) columns are also compared to the space-based Infrared Atmospheric Sounding Interferometer(IASI)measurements, and we find that the two instruments observe a consistent NH_(3) global distribution, with correlation coefficient(R) values of 0.28–0.73. Finally, some remaining issues about the HIRAS NH_(3) retrieval are discussed.
基金Natural Science Foundation of Shandong Province (Y2000E08) the bargain item of China Earthquake Administration in the year 2002.
文摘Wavelet transform method is applied to measure time-frequency distribution characteristics of digital deformation data and noise. Based on the characteristics of primary modulus and stochastic white noise discrimination factor of wavelet decomposition, we analyze the variation rule of normal background and noise data from Shandong digital deformation observation data. The research results indicate that: a) 1/4 daily wave, semi-diurnal tide wave, daily wave and half lunar wave and so on quasi-periodic signal exist in the detail decomposing signal of wavelet when scale are equal to 2, 3 and 4; b) The amplitude of detail decomposing signal is the biggest when scale is equal to 3; c) The detail decomposing signal contains mainly noise corresponding to scale 1 and 5, respectively; d) We may trace the abnormal precursory which is related to earthquake by analyzing non-earthquake wavelet decomposing signal whose scale is specified from digital deformation observation data.
基金supported by the National Basic Research Program of China (973 program, Nos. 2015CB857000 and 2013CB834900)the Foundation for Distinguished Young Scholars of Jiangsu Province (No. BK20140050)+1 种基金the ‘Strategic Priority Research Program the Emergence of Cosmological Structure’ of the CAS (No. XDB09010000)the National Natural Science Foundation of China (Nos. 11333008, 11233005, 11273061 and 11673065)
文摘By employing the previous Voronoi approach and replacing its nearest neighbor approx- imation with Drizzle in iterative signal extraction, we develop a fast iterative Drizzle algorithm, namedfiDrizzle, to reconstruct the underlying band-limited image from undersampled dithered frames. Compared with the existing iDrizzle, the new algorithm improves rate of convergence and accelerates the computational speed. Moreover, under the same conditions (e.g. the same number of dithers and iterations), fiDrizzle can make a better quality reconstruction than iDrizzle, due to the newly discov- ered High Sampling caused Decelerating Convergence (HSDC) effect in the iterative signal extraction process.fiDrizzle demonstrates its powerful ability to perform image deconvolution from undersampled dithers.
文摘OBJECTIVE: To compare the clinical effect of brachial plexus block with "One Injection Two Points" guided under ultrasound and the conventional method guiding by ultrasound. METHODS: 70 patients were randomized evenly into 2 groups, with 35 patients in each group, while the Experiment Group(Group B) received One Injection Two Points" method, the Control Group(Group A) received the conventional method.The nerve block every 5 s, the success rate of anesthesia, the dosage of local anesthetics, second remedial anesthesia, adverse reactions, etc.were recorded. RESULTS: Group B was superior to group A in the success rate of anesthesia; There were 6 patients in group A who required constant pump injection of Remifentanil to remedy, while no patients in Group B needed remedy treatment. There were no serious adverse reactions in both groups.CONCLUSIONS: The clinical effect of brachial plexus block with "One Injection Two Points" method guided under ultrasoundguiding by ultrasound was superior to that of the conventional method.
基金supported by FAU Start-up funding at the C. E. Schmidt Collegeof Science
文摘We study the least squares estimation of drift parameters for a class of stochastic differential equations driven by small a-stable noises, observed at n regularly spaced time points ti = i/n, i = 1,...,n on [0, 1]. Under some regularity conditions, we obtain the consistency and the rate of convergence of the least squares estimator (LSE) when a small dispersion parameter ε→0 and n →∞ simultaneously. The asymptotic distribution of the LSE in our setting is shown to be stable, which is completely different from the classical cases where asymptotic distributions are normal.
基金supported by the National Natural Science Foundation of China (Grant Nos. 11790301, 11790305, 11973057, 12003048, 11903055, 11773043 and 12003049)supported by the Ministry of Science and Technology of China Key Project (2018YFA0404602)the international collaboration of ISSI-BJ
文摘The solar radio signal that can be received by the ground-based telescopes covers a wide frequency range,allowing us to monitor the complex physical processes occurred from the solar surface to the vast interplanetary space.MingantU SpEctral Radioheliograph(MUSER),as the latest generation of solar dedicated radio spectral-imaging instrument in the centimeter-decimeter wavelengths,has accumulated a large number of observational data since its commissioning observation in 2014.This paper presents the main observational results identified by MUSER from 2014 to 2019,including the quiet Sun and 94 solar radio burst events.We find that there are 81 events accompanied with Geostationary Operational Environmental Satellites(GOES)soft X-ray(SXR)flares,among which the smallest flare class is B1.0.There are 13 events without accompanying any recorded flares,among which the smallest SXR intensity during the radio burst period is equivalent to level-A.The main characteristics of all radio burst events are presented,which shows the powerful ability of MUSER to capture the valuable information of the solar non-thermal processes and the importance for space weather.This work also provides a database for further in-depth research.
基金supported by the National Natural Science Foundation of China(Grant Nos.11873062,11427901,11673038,11803002,11973056,11973061,12003051 and 12073040)supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant Nos.XDA15320102 and XDA15052200)。
文摘The Fourier transform spectrometer(FTS)is a core instrument for solar observation with high spectral resolution,especially in the infrared.The Infrared System for the Accurate Measurement of Solar Magnetic Field(AIMS),working at 10-13μm,will use an FTS to observe the solar spectrum.The Bruker IFS-125 HR,which meets the spectral resolution requirement of AIMS but simply equips with a point source detector,is employed to carry out preliminary experiment for AIMS.A sun-light feeding experimental system is further developed.Several experiments are taken with them during 2018 and 2019 to observe the solar spectrum in the visible and near infrared wavelength,respectively.We also proposed an inversion method to retrieve the solar spectrum from the observed interferogram and compared it with the standard solar spectrum atlas.Although there is a wavelength limitation due to the present sun-light feeding system,the results in the wavelength band from 0.45-1.0μm and 1.0-2.2μm show a good consistency with the solar spectrum atlas,indicating the validity of our observing configuration,the data analysis method and the potential to work in longer wavelength.The work provided valuable experience for the AIMS not only for the operation of an FTS but also for the development of its scientific data processing software.
文摘Often in longitudinal studies, some subjects complete their follow-up visits, but others miss their visits due to various reasons. For those who miss follow-up visits, some of them might learn that the event of interest has already happened when they come back. In this case, not only are their event times interval-censored, but also their time-dependent measurements are incomplete. This problem was motivated by a national longitudinal survey of youth data. Maximum likelihood estimation (MLE) method based on expectation-maximization (EM) algorithm is used for parameter estimation. Then missing information principle is applied to estimate the variance-covariance matrix of the MLEs. Simulation studies demonstrate that the proposed method works well in terms of bias, standard error, and power for samples of moderate size. The national longitudinal survey of youth 1997 (NLSY97) data is analyzed for illustration.
基金supported by the National Natural Science Foundation of China(Grant Nos.10973022 and 10873039)
文摘The Zhoubi Suanjing, one of the most important ancient Chinese books on mathematical astronomy, was compiled about 100 BC in the Western Han dynasty (BC 206 - AD 23). We study the gnomon shadow lengths for the 24 solar terms as recorded in the book. Special attention is paid to the so-called law of ‘cun qian li’, which says the shadow length of a gnomon of 8 chi (about 1.96 m) high will increase (or decrease) 1 cun (1/10chi) for every 10001i (roughly 400kin) the gnomon moves northward (or south- ward). From these data, one can derive the time and location of the observations. The resuits, however, do not fit historical facts. We suggest that compilers of the Zhoubi Suanjing must have modified the original data according to the law of ‘cun qian li’. Through reversing the situation, we recovered the original data, our analysis of which reveals the best possible observation time as 564 BC and the location of observation as 35.78° N latitude. We conclude that this must be the earliest records of solar meridian observations in China. In the meantime, we give the errors of solar altitudes for the 24 solar terms. The average deviation is 5.22°, and the mean absolute deviation is 5.52°, signifying the accuracy of astronomical calculations from that time.
基金Supported by(Major) Project for Key Technology Integration and Application of China Meteorological Administration(CMAGJ2015Z17)
文摘With the rapid development of China s economic construction and the rapid advancement of urban-rural integration construction, meteorological detection environment has been damaged repeatedly, which seriously affects the representativeness, accuracy, and comparability of meteorological data, so it is urgent to protect meteorological detection environment. Based on the investigation and evaluation method of detection environment of national ground meteorological observation stations and high-altitude meteorological observation stations, satellite remote sensing data, and climate analysis method, the evaluation method of detection environment and meteorological data was improved to comprehensively assess the detection environment and meteorological data of stations. After the evaluation results were compared with the results of the survey and evaluation in 2013, it is found that the new assessment method maintains the continuity of detection environment assessment and can objectively reflect the changes of the station detection environment. The research on the method and standard for the evaluation of detection environment and data analysis of meteorological stations provides a scientific basis for the establishment of detection environmental protection plans by stations at all levels, and provides technical support for the scientific and rational adjustment of station network by administrative departments at all levels.
基金Supported by the National Natural Science Foundation of China under Grant No.19673010。
文摘The quasar PKSO528+134 was observed to flare by the energetic gamma-ray experiment(EGR-ET)γ-ray telescope on the Compton gamma-ray observatory during the viewing period 213(VP213).The Compton telescope data from VP213 have been reanalyzed by using the direct demodulation method.Images of the source are obtained at energies above 3 MeV and the time variability in the energy range 10-30 MeV is consistent with the result of EGRET.There is no spectral break at energies above 3 MeV during the flare.
文摘Data of traffic flow, speed and density are required for planning, designing, and modelling of traffic stream for all parts of the road system. Specialized equipments such as stationary counts are used to record volume and speed;but they are expensive, difficult to set up, and require periodic maintenance. The moving observer method was proposed in 1954 by Wardrop and Charlesworth to estimate these variables inexpensively. Basically, the observer counts the number of vehicles overtaken, the number of vehicles passed, and the number of vehicles encountered while traveling in the opposite direction. The trip time is reported for both travel directions. Additionally, the length of road segment is measured. These variables are then used in estimating speeds and volumes. In a westbound direction from Interstate Highway 30 (I-30) in the DFW area, this study examined the accuracy and feasibility of this method by comparing it with stationary observer method as the standard method for such counts. The statistical tests were used to test the accuracy. Results show that this method provides accurate volume and speed estimates when compared to the stationary method for the road segment with three lanes per direction, especially when several runs are taken.