中国科学院机构知识库网格系统: 检索

User Influence in Microblog Based on Interest Graph 期刊论文 OAI收割
INTERNATIONAL JOURNAL OF SOFTWARE ENGINEERING AND KNOWLEDGE ENGINEERING, 2018, 卷号: 28, 期号: 2, 页码: 207-217
作者: Zhai, Lidong; Wang, Jingya; Hu, Chaojian; Li, Jun

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Microblogs LDA label propagation algorithm interest graph influence calculation

Research on the torque characteristic of disc micromotor on axial magnetic field (EI CONFERENCE) 会议论文 OAI收割
2012 2nd International Conference on Consumer Electronics, Communications and Networks, CECNet 2012, April 21, 2012 - April 23, 2012, Three Gorges, China
Liu B.

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In order to increase the electromagnetic torque density of micromotor with axial magnetic field numerical analysis of permanent magnetic field and electromagnetic torque were deduced and the key factors of increasing torque density of micromotor was obtained. The numerical analysis of three-dimensional magnetic field in air gap produced by spliced sector permanent magnetic poles is done and the way of improving flux density and permanent magnet use efficiency are given through investigating the influence of magnet thickness height of air gap and pole interval rate and other parameters to air gap flux density and leakage flux. Based on the test of axial magnetic field and torque characteristic of micromotor the analysis of micromotor magnetic field and calculation of torque are verified meanwhile using the plane stator with 0.7mm thickness assemble micromotor having minimum air gap height of 1mm and its torque constant up to 3.8mNm/A. 2012 IEEE.

Design of motion adjusting system for space camera based on ultrasonic motor (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
作者: Sun Z.

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Drift angle is a transverse intersection angle of vector of image motion of the space camera. Adjusting the angle could reduce the influence on image quality. Ultrasonic motor (USM) is a new type of actuator using ultrasonic wave stimulated by piezoelectric ceramics. They have many advantages in comparison with conventional electromagnetic motors. In this paper some improvement was designed for control system of drift adjusting mechanism. Based on ultrasonic motor T-60 was designed the drift adjusting system which is composed of the drift adjusting mechanical frame the ultrasonic motor the driver of Ultrasonic Motor the photoelectric encoder and the drift adjusting controller. The TMS320F28335 DSP was adopted as the calculation and control processor photoelectric encoder was used as sensor of position closed loop system and the voltage driving circuit designed as generator of ultrasonic wave. It was built the mathematic model of drive circuit of the ultrasonic motor T-60 using matlab modules. In order to verify the validity of the drift adjusting system was introduced the source of the disturbance and made simulation analysis. It designed the control systems of motor drive for drift adjusting system with the improved PID control. The drift angle adjusting system has such advantages as the small space simple configuration high position control precision fine repeatability self locking property and low powers. It showed that the system could accomplish the mission of drift angle adjusting excellent. 2011 SPIE.

An appraisal method of dynamic interpolation error for high precision encoder (EI CONFERENCE) 会议论文 OAI收割
2011 International Conference on Electronics and Optoelectronics, ICEOE 2011, July 29, 2011 - July 31, 2011, Dalian, China
作者: Wan Q.-H.; Liu C.-X.; Liu C.-X.

收藏 | 浏览/下载：18/0 | 提交时间：2013/03/25

This paper introduces an appraisal method of the dynamic interpolation error for the high precision encoder (Lissajou pattern calculation method). When the encoder is rolling two groups of fine photoelectric signals whose phase difference are /2 can be collected using data collected car. The shape and position deviation can be obtained through the comparison between Lissajou charts and the standard circle. Then dynamic interpolation error can be calculated out directly. This method is immune to the influence of encoder's speed and has no rigid demand to the test circumstances and test devices. The experimental results indicate that this method is feasible and important to the encoder's dynamic interpolation error checking. 2011 IEEE.

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

Evaluation of the operating range for ground-based infrared imaging tracking system (EI CONFERENCE) 会议论文 OAI收割
International Symposium on Photoelectronic Detection and Imaging 2011: Advances in Infrared Imaging and Applications, May 24, 2011 - May 24, 2011, Beijing, China
作者: Zhang Z.-D.

收藏 | 浏览/下载：48/0 | 提交时间：2013/03/25

Ground-based infrared imaging tracking system (GIITS) is of great importance for aerial target warning and guard. The operating range is one of the key performance specifications on the other which should be calculated calculate the radiation power received on the detector in order to analysis whether the output signal meets the detection requirements or not analyzed and studied during the whole GIITS design process. The operating range is mostly influenced by a few factors without considering the effect of the background radiation. By improving of the traditional method including atmospheric attenuation a new operating range calculation model of the GIITS was established based on two requirements. One is that the image size of observed target should meet the requirement of the processor signal extraction. The number of the pixel occupied by target image should be more than 9. The other is that the signal noise ratio (SNR) of the GIITS should not be less than 5 to meet the requirements of the target detection probability and spatial frequency. The SNR calculation equation in form of energy is deduced and the radiation characteristic of the observed target and background are analyzed. When evaluate the operating range of the GIITS using the new method the performance of GIITS and feature of target and background. This paper firstly makes analysis and summarization on the definite localizations of the traditional operating range equation of the GIITS. The localizations are mainly in two aspects. On one hand we should successively calculate two operating range values according to two requirements mentioned above and choose the minimum value as the analytic result. In the end the dispersion of the image and the effect of image dispersion are not considered in the traditional method an evaluation of operating range for fighter aircraft is accomplished as an example. The influence factors in every aspect on operating range were explored by the calculated result. The new operating range calculation model provides the theoretical basis for the design and applications as well as the comprehensive evaluation of a GIITS. 2011 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).

Study on the flutter model of the imaging quality of TDICCD space camera (EI CONFERENCE) 会议论文 OAI收割
2011 International Conference on Advanced Engineering Materials and Technology, AEMT 2011, July 29, 2011 - July 31, 2011, Sanya, China
作者: Chen X.; Chen X.; Chen X.

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For any On-orbit Space camera the influence of flutter on the imaging process of TDICCD space camera is inevitable thus causing the decline of image quality. This paper briefly introduces the principle of TIDCCD camera and how flutter affects the imaging process. Then through the analysis and calculation of practical program we find the acceleration criterion to avoid the blur of image quality. (2011) Trans Tech Publications.

Study of the neural network constitutive models for turfy soil with different decomposition degree (EI CONFERENCE) 会议论文 OAI收割
2011 2nd International Conference on Mechanic Automation and Control Engineering, MACE 2011, July 15, 2011 - July 17, 2011, Inner Mongolia, China
作者: Nie L.

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The turfy soil is of a special humus soil. The decomposition degree is the main factor on the physical and mechanical properties of turfy soil. To build the turfy soil constitutive model there are a few shortages such as the calculation cumbersome and low accuracy for parameter value with the method of traditional models. Furthermore those methods did not reflect the influence of strength that effected by decomposition degree of the turfy soil. In this paper the relationship of stress-strain with different decomposition degrees of turfy soil was carried out through indoor tests. Based on above experimental results an improved method which divided into different zones according to different decomposition degrees of turfy soil and calculated combining with neural network constitutive model is put forward. The result shows that the neural network of turfy soil has good fitting precision and good generalization ability. It can fully describe the influence of the turfy soil. 2011 IEEE.

The Research of real time auto-recognition of the moire fringe (EI CONFERENCE) 会议论文 OAI收割
International Symposium on Photoelectronic Detection and Imaging 2011: Advances in Imaging Detectors and Applications, May 24, 2011 - May 26, 2011, Beijing, China
Wang M.-J.; Wu Z.-G.

收藏 | 浏览/下载：19/0 | 提交时间：2013/03/25

Measuring the movement of raster by the method of moire fringe has the advantage of high sensitivity high resolution and non-contacted measurement. The characteristic of moire fringe is that the image is white alternate with black the angle of the stripes is uniform the width of the stripes is uniform the terminators of the stripes aren't clear. A fast method that can figure out the width and angle of the moire fringe precisely is put forward in this paper. It calculates the angle the stripes firstly. According to the principle of the minimum mean squared error (MMSE) the closer a series of data is the smaller the value of the MMSE will be. The method is described as follows: It takes the image's center as the origin 180 beelines pass through the origin with the same angle interval. it calculates the value of the minimum mean squared error of the 180 beelines and find out the least one among those then the angle of the moire fringe comes out primarily. In order to improving the calculating precision of moire fringe 60 equal angles are divided in the neighborhood of the angle then a precise angle of moire fringe is calculated according to the principle of the MMSE. After getting out the angle of the moire fringe we begin to calculate the width of moire fringe. A line vertical with the moire fringe is drawn and we can get the width of the moire fringe by the vertical line. In order to get over the influence of the noise an effective area with the shape of diamond is selected in the image. The data of area is accumulated and projected according to the direction of moire fringe and a sine curve come out. The width of moire fringe can be obtained by getting the position of the first wave crest the position of the last wave crest and the number of wave crest. Experiments prove that the precision of the method put forward in this paper is enhanced in comparison with the traditional frequency method the precision of width calculation achieves to 99.6% according to the evaluation indicators of width detection error. The computing speed is boosted largely compared with traditional method and it can achieve with 15 ms that satisfying the demand of real time. 2011 SPIE.

Analysis of laser jamming to satellite-based detector (EI CONFERENCE) 会议论文 OAI收割
International Symposium on Photoelectronic Detection and Imaging 2009: Laser Sensing and Imaging, June 17, 2009 - June 19, 2009, Beijing, China
作者: Guo L.-H.; Guo R.-H.; Wang S.-W.

收藏 | 浏览/下载：29/0 | 提交时间：2013/03/25

The reconnaissance satellite communication satellite and navigation satellite used in the military applications have played more and more important role in the advanced technique wars and already become the significant support and aid system for military actions. With the development of all kinds of satellites anti-satellite laser weapons emerge as the times require. The experiments and analyses of laser disturbing CCD (charge coupled detector) in near ground have been studied by many research groups but their results are not suitable to the case that using laser disturbs the satellite-based detector. Because the distance between the satellite-based detector and the ground is very large it is difficult to damage it directly. However the optical receive system of satellite detector has large optical gain so laser disturbing satellite detector is possible. In order to determine its feasibility the theoretical analyses and experimental study are carried out in the paper. Firstly the influence factors of laser disturbing satellite detector are analyzed in detail which including laser power density on the surface of the detector after long distance transmission and laser power density threshold for disturbing etc. These factors are not only induced by the satellite orbit but dependence on the following parameters: laser average power in the ground laser beam quality tracing and aiming precision and atmospheric transmission. A calculation model is developed by considering all factors which then the power density entering into the detector can be calculated. Secondly the laser disturbing experiment is performed by using LD (laser diode) with the wavelength 808 nm disturbing CCD 5 kilometer away which the disturbing threshold value is obtained as 3.5510-4mW/cm2 that coincides with other researcher's results. Finally using the theoretical model the energy density of laser on the photosensitive surface of MSTI-3 satellite detector is estimated as about 100mW/cm2 which is largely exceed the disturbing threshold and therefore verify the feasibility of using this kind of laser disturbing the satellite-based detector. According to the results. using the similar laser power density absolutely saturate the requirements to laser disturbing satellite-based detector. If considering the peak power of pulsed laser even decrease laser average power it is also possible to damage the detector. This result will provide the reliable evidences to evaluate the effect of laser disturbing satellite-based detector. 2009 SPIE.