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Spatiotemporal heterogeneity in associations of national population ageing with socioeconomic and environmental factors at the global scale 期刊论文  OAI收割
JOURNAL OF CLEANER PRODUCTION, 2022, 卷号: 373, 页码: 13
作者:  Wan, Qin;  Tang, Zhangying;  Pan, Jay;  Xie, Mingyu;  Wang, Shaobin
  |  收藏  |  浏览/下载：47/0  |  提交时间：2022/11/09
Comparison of simulated backgrounds with in-orbit observations for HE, ME, and LE onboard Insight-HXMT 期刊论文  OAI收割
Astrophysics and Space Science, 2020, 卷号: 365, 页码: 158
作者:  HXMT
  |  收藏  |  浏览/下载：49/0  |  提交时间：2022/02/08
Insight-HXMT  Geant4 simulation  Background observation  Astrophysics  - Instrumentation and Methods for Astrophysics  Abstract: Insight-HXMT, the first X-ray astronomical satellite in China, aims to reveal new sources in the Galaxy and to study fundamental physics of X-ray binaries from 1 to 250 keV. It has three collimated telescopes, the High Energy X-ray telescope (HE), the Medium Energy X-ray telescope (ME), and the Low Energy X-ray telescope (LE). Before the launch, in-orbit backgrounds of these three telescopes had been estimated through Geant4 simulation, in order to investigate the instrument performance and the achievement of scientific goals. In this work, these simulated backgrounds are compared with in-orbit observations. Good agreements are shown for all three telescopes. For HE, (1) the deviation of the simulated background rate after two years of operation in space is 5 % from the observation  (2) the total background spectrum and the relative abundance of the 67 keV line show long-term increases both in simulations and observations. For ME, (1) the deviation of simulated background rate is within 15 % from the observation, and (2) there are no obvious long-term increase features in the background spectra of simulations and observations. For LE, the background level given by simulations is also consistent with observations. The consistencies of these comparisons validate that the Insight-HXMT mass model, i.e., space environment components and models adopted, physics processes selected, and detector constructions built, is reasonable. However, the line features at 7.5 and 8.0 keV, which are obvious in the observed spectra of LE, are not evident in simulations. This might result from uncertainties in the LE constructions.  
Temporal stability of soil water storage analysis by the improved mean relative difference in two deposited-soil farmlands SCI/SSCI论文  OAI收割
2016
作者:  Zhao P.;  Li, L.;  Shao, M. G.;  Li, WH;  Fu, XL
收藏  |  浏览/下载：34/0  |  提交时间：2016/12/16
Analysis of the applicability of collision probability algorithms for nonlinear relative motion 期刊论文  OAI收割
SCIENCE CHINA-PHYSICS MECHANICS & ASTRONOMY, 2013, 卷号: 56, 期号: 5, 页码: 1041-1046
作者:  Xu XiaoLi;  Xiong YongQing
收藏  |  浏览/下载：33/0  |  提交时间：2014/01/08
Quadratic Programming-based Approach for Autonomous Vehicle Path Planning in Space 期刊论文  OAI收割
CHINESE JOURNAL OF MECHANICAL ENGINEERING, 2012, 卷号: 25, 期号: 4, 页码: 665-673
作者:  Chen Y(陈洋);  Han JD(韩建达);  Wu HY(吴怀宇)
收藏  |  浏览/下载：19/0  |  提交时间：2012/10/24
Global estimation of evapotranspiration using a leaf area index-based surface energy and water balance model SCI/SSCI论文  OAI收割
2012
作者:  Yan H.
收藏  |  浏览/下载：36/0  |  提交时间：2014/12/24
Design of motion compensation mechanism of satellite remote sensing camera (EI CONFERENCE) 会议论文  OAI收割
International Symposium on Photoelectronic Detection and Imaging 2011: Space Exploration Technologies and Applications, May 24, 2011 - May 26, 2011, Beijing, China
Gu S.; Yan Y.; Xu K.; Jin G.
收藏  |  浏览/下载：47/0  |  提交时间：2013/03/25
With the development of aerospace remote sensing technology  the ground resolution of remote sensing camera enhances continuously. Since there is relative motion between camera and ground target when taking pictures  the target image recorded in recording media is moved and blurred. In order to enhance the imaging quality and resolution of the camera  the image motion had to be compensated. In order to abate the effect of image motion to image quality of space camera and improve the resolution of the camera  the compensation method of image motion to space camera is researched. First  the reason of producing drift angle and adjustment principle are analyzed in this paper. This paper introduce the composition and transmission principle of image motion compensation mechanism. Second  the system adopts 80C31 as controller of drift angle  and adopts stepping motor for actuators  and adopts absolute photoelectric encoder as the drift Angle measuring element. Then the control mathematical model of the image motion compensation mechanism are deduced  and it achieve the closed-loop control of the drift angle position. At the last  this paper analyses the transmission precision of the mechanism. Through the experiment  we measured the actual precision of the image motion compensation mechanism  and compared with the theoretical analysis. There are two major contributions in this paper. First  the traditional image motion compensation mechanism is big volume and quality heavy. This has not fit for the development trend of space camera miniaturization and lightweight. But if reduce the volume and quality of mechanism  it will bring adverse effects for the precision and stiffness of mechanism. For this problem  This paper designed a image motion compensation that have some advantages such as small size  light weight at the same time  high precision  stiffness and so on. This image motion compensation can be applicable to the small optics cameras with high resolution. Second  the traditional mechanism control need to corrected  fitting and iterative for the control formula of mechanism. Only in this way  we can get the optimal control mathematical model. This paper has high precision of the control formula derived. It can achieve the high precision control without fitting  It also simplify the difficulty of control mathematical model establishment. This paper designed the range of adjusting of image motion compensation mechanism between -5 +5. Based on choosing-5  -4  -3  -2  -1  0  +1  +2  +3  +4  +4 as the expectation value of the imaginary drift angle  we get ten groups of the fact data in adjusting drift angle measured. The test results show that the precision of the drift angle control system can be achieved in 1. It can meet the system requirements that the precision of the control system is less than 3'  and it can achieve the high-precision image motion compensation. 2011 SPIE.  
Geocentric distance's errors' correction of space cameras based on USGS DEM (EI CONFERENCE) 会议论文  OAI收割
2011 IEEE 3rd International Conference on Communication Software and Networks, ICCSN 2011, May 27, 2011 - May 29, 2011, Xi'an, China
作者:  Li W.;  Li W.;  Xu S.
收藏  |  浏览/下载：25/0  |  提交时间：2013/03/25
In order to correct the geocentric distance's error of TDI (Time Delay and Integration) CCD space camera in calculation of image motion compensation  the data source of the earth's height above sea level USGS DEM (United States Geological Survey Digital Elevation Model) has been introduced to make digital elevation map  the match error of the forward direction (the integral direction of TDI CCD) has been greatly decreased by correcting the geocentric distance error  and eliminate the influence to the relative error of image motion velocity  and correct the error generated by the different heights above sea level. After correcting  which greatly improves the imaging quality of TDI CCD space camera. 2011 IEEE.  a model of image motion calculation of nadir has been introduced  the calculation and analysis of the model shows that: the maximum error of image motion velocity about 1.72% has been decreased to 0.06%  and the influence of the geocentric distance error to the relative error of image motion velocity has been analyzed with the model  
Dynamic coupling analysis and modeling for stabilized platform of rolling-pitching seeker (EI CONFERENCE) 会议论文  OAI收割
2011 International Conference on Electric Information and Control Engineering, ICEICE 2011, April 15, 2011 - April 17, 2011, Wuhan, China
作者:  Liu H.;  Liu H.;  Liu H.
收藏  |  浏览/下载：12/0  |  提交时间：2013/03/25
Missile's attitude change will be delivered to visual axis through stabilized platform during maneuvering flight  and the missile vibration will be an interference source to visual axis stabilization. In order to solve this problem  the coupling relationship between missile attitude and visual axis is obtained by Coordinate transformation. When the seeker stably tracks a target  the angular velocity of visual axis in inertial space is zero  so the relative angular velocity of roll axis and pitch axis can be derived for servo control. According to Oura dynamics equation  the dynamic models of roll axis and pitch axis were established and kinetic equations of two axises were obtained. The dynamic models can provide theoretical basis to developing research of servo control system and structural optimization design of stabilized platform. Finally  some measures could reduce the dynamic coupling between the framework was given. 2011 IEEE.  
High precision test method for dynamic imaging of space camera (EI CONFERENCE) 会议论文  OAI收割
2010 IEEE International Conference on Advanced Computer Control, ICACC 2010, March 27, 2010 - March 29, 2010, 445 Hoes Lane - P.O.Box 1331, Piscataway, NJ 08855-1331, United States
作者:  Jin L.-X.;  Zhang K.;  Zhang K.;  Zhang K.;  Zhang K.
收藏  |  浏览/下载：26/0  |  提交时间：2013/03/25
A test method for dynamic imaging of space TDICCD (Time Delay and Integration Charge Coupled Devices) camera was presented in this paper. The test method adopted the PLL (Phase Locked Loop) technology and CMAC (Cerebella Model Articulation Controller) friction compensation as control strategy. Furthermore  According to this method  a test system for dynamic imaging of space TDICCD camera was designed and implemented. The system simulated the movement of the ground objects relative to the space aerocraft  to validate the capability of image speed match and the dynamic imaging quality of TDICCD camera. The design adopted a precision turntable and a drift turntable to simulate the movement around the earth and the drift motion in different latitude due to the rotation of earth  of the aerocraft. The turntables were drived by permanent magnet torque motor which was powered by PWM (Pulse Width Modulation). The system adopted DSP (Digital Signal Processor) as the control core and reached a very high performance. The experimental results showed that the steady speed error was better than 0.01 % and the instantaneous speed error reached 0.0267%. The precision of the test system designed met the requirement for dynamic imaging of TDICCD camera. 2010 IEEE.