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Understanding the acceleration phenomenon via high-resolution differential equations
期刊论文
OAI收割
MATHEMATICAL PROGRAMMING, 2022, 卷号: 195, 期号: 1-2, 页码: 79-148
作者:
Shi, Bin
;
Du, Simon S.
;
Jordan, Michael, I
;
Su, Weijie J.
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收藏
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浏览/下载:30/0
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提交时间:2023/02/07
Convex optimization
First-order method
Polyak's heavy ball method
Nesterov's accelerated gradient methods
Ordinary differential equation
Lyapunov function
Gradient minimization
Secondary-field boosted caloric effect associated with first-order phase transition, a quasi-direct measurement
期刊论文
OAI收割
SCRIPTA MATERIALIA, 2022, 卷号: 218
作者:
Tao, Kun
;
Song, Wenhai
;
Tong, Peng
;
Xiong, Tingjiao
;
Wang, Tianyang
|
收藏
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浏览/下载:34/0
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提交时间:2022/12/23
Quasi-direct method
Caloric effect
First-order phase transition
Hysteresis
Reversible isothermal entropy change
Numerical manifold computational homogenization for hydro-dynamic analysis of discontinuous heterogeneous porous media
期刊论文
OAI收割
COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING, 2022, 卷号: 388, 页码: 53
作者:
Wu, Wenan
;
Yang, Yongtao
;
Zheng, Hong
;
Zhang, Limei
;
Zhang, Ning
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收藏
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浏览/下载:65/0
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提交时间:2022/01/05
Multiscale analysis
First-order homogenization
Numerical manifold method
Discontinuous heterogeneous porous media
Wave propagation
Hybrid optimization methodology of variable densities mesh model for the axial supporting design of wide-field survey telescope
期刊论文
OAI收割
OPTICAL ENGINEERING, 2016, 卷号: 55, 期号: 3
作者:
Wang, Hairen
;
Lou, Zheng
;
Qian, Yuan
;
Zheng, Xianzhong
;
Zuo, Yingxi
收藏
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浏览/下载:25/0
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提交时间:2016/09/27
hybrid optimization methodology
variable densities mesh model
axial support optimization
primary mirror
zero-order optimization method
first-order optimization method
Structural design of primary mirror subassembly for space telescope (EI CONFERENCE)
会议论文
OAI收割
2nd International Conference on Mechatronics and Applied Mechanics, ICMAM 2012, December 8, 2012 - December 9, 2012, Taiwan
作者:
Xu H.
收藏
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浏览/下载:64/0
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提交时间:2013/03/25
In order to design a large aperture primary mirror with the diameter of 1150 mm
the parameters impacting on gravity deformation of the mirror were analyzed and discussed in detail
including material selection
diameter-thickness ratio
the number of the support points
location selection and lightweight structure
etc. A novel space mirror structure system was put forward
and its back was opened and supported by six points on back. The dynamic and static and thermal characteristics were analyzed based on the finite element method. Analysis results showed the surface figure accuracy reached to RMS 14.5nm under the action of gravity load along the optical axis direction and the first-order natural frequency was 214Hz which met to the designed indexes requirements. (2013) Trans Tech Publications
Switzerland.
A Local Image Enhancement Method Based on Adjacent Pixel Gray Order-preserving Principle
会议论文
OAI收割
5th International Symposium on Photoelectronic Detection and Imaging (ISPDI) - Infrared Imaging and Applications, Beijing, June 25-27, 2013
作者:
Fan XP(范晓鹏)
;
Cai TF(蔡铁峰)
;
Zhu F(朱枫)
收藏
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浏览/下载:43/0
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提交时间:2013/12/26
The paper is committed in local image enhancement. At first, the authors propose an adjacent pixel gray order-preserving principle. Adjacent pixel gray order-preserving principle is the basement of local enhancement method which ensures that there is no distortion in processed image. And then, the authors propose an iterative algorithm, which could stretch gray-scale difference of adjacent pixels in premise of not changing gray magnitude relationship between adjacent pixels. At last, the authors propose a totally reference image quality assessment method based on adjacent pixel gray order-preserving principle. According to this quality assessment method, the authors made a set of comparative experiments with local histogram equalization and method. Experimental results show that the proposed enhancement method can get higher score and provide better visual effects, fully demonstrating its effectiveness. According to this quality assessment method, the proposed method shows a good effectiveness, through experimental results and comparison with local histogram equalization method.
LED display panel grayscale modulation based on computer calculation (EI CONFERENCE)
会议论文
OAI收割
2012 International Applied Mechanics, Mechatronics Automation Symposium, IAMMAS 2012, September 7, 2012 - September 9, 2012, Shenyang, Liaoning, China
Wang R.-g.
;
Chang F.
收藏
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浏览/下载:26/0
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提交时间:2013/03/25
In order to improve the method of the LED display panel grayscale modulation a method based on computer calculation is proposed. First the development history and trends of the LED display panel are introduced. Second present the structure of the LED display panel and the existed modulation method. Simultaneously point out the ground for shortcomings of the existed method. Third describe the principle modulation method based on computer calculation detail from two steps which are the data signal transformation and the grayscale modulation. Forth describe the realization steps of this method in accordance with the third step. Finally this method is supplied in a LED display panel whose resolution is 320240. Experimental results show that this method is able to increase the grayscale from 14-bit to 16-bit and can enhance the display result of the LED display panel significantly. (2012) Trans Tech Publications Switzerland.
Application of trend extrapolation method to spectrum analysis of microtremor signal (EI CONFERENCE)
会议论文
OAI收割
2nd World Congress on Computer Science and Information Engineering, CSIE 2011, June 17, 2011 - June 19, 2011, Changchun, China
Zhou X.
;
Guo T.
;
Jiao J.
收藏
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浏览/下载:30/0
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提交时间:2013/03/25
The trend extrapolation method is applied to spectrum analysis of microtremor signal in order to increase the spectral estimation accuracy. First
establish an appropriate extrapolation model based on the existing data series
and then fit correlation functions other than existing data by derivative least squares method
finally perform spectrum analysis using extrapolated correlation functions. Numerical simulations and the experimental results show that good results are achieved no matter correlation functions change slow or rapid
and the extrapolation error is not more than 2.3%. 2012 Springer-Verlag Berlin Heidelberg.
The electromagnetic compatibility design of restrained image transmission equipments (EI CONFERENCE)
会议论文
OAI收割
2011 3rd International Conference on Mechanical and Electronics Engineering, ICMEE 2011, September 23, 2011 - September 25, 2011, Hefei, China
作者:
Wang W.
;
Wang W.
收藏
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浏览/下载:31/0
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提交时间:2013/03/25
In order to improve the quality of image transmission
this paper puts forward a box shielding method that could eliminate electromagnetic interference signal on image transmission equipments. At first
this paper analyzes the shielding effectiveness of electromagnetic interference
selects the qualified shielding material and designs the structure. After that
it analyzes the descending of shielding effectiveness in the operational system
and improves the equipments shielding effectiveness by means of the electromagnetic compatibility design that accords with electromagnetic compatibility norms. At last
through the EMI radiometry
this paper confirms that the equipments are in accordance with the design requirements of electromagnetic compatibility norms. (2012) Trans Tech Publications
Switzerland.
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
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浏览/下载:48/0
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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.
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