中国科学院机构知识库网格系统: 检索

浏览/检索结果: 共5条，第1-5条

帮助

条数/页：排序方式：
	A Comprehensive Comparison and Analysis of Several Intensity Modulations Based on the Underwater Photon-Counting Communication System 期刊论文 OAI收割 FRONTIERS IN PHYSICS, 2022, 卷号: 9 作者: Han, Xiaotian; Li, Peng; Chang, Chang; Gao, Duorui; Zhang, Dongquan \| 收藏 \| 浏览/下载：46/0 \| 提交时间：2022/03/11 underwater wireless optical communication (UWOC) intensity modulation (IM) direct detection (DD) digital pulse modulation photon counting channel model
	基于闭环霍尔电流传感器驱动电路的设计期刊论文 OAI收割控制工程, 2020, 卷号: 27 - \| 收藏 \| 浏览/下载：61/0 \| 提交时间：2020/10/26 Hall zero magnetic current sensor pulse width modulation digital drive circuit digital signal processing 霍尔零磁通电流传感器脉冲宽度调制数字驱动电路数字信号处理
	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：38/0 \| 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.
	The compression and storage method of the same kind of medical images-DPCM (EI CONFERENCE) 会议论文 OAI收割 4th International Conference on Photonics and Imaging in Biology and Medicine, September 3, 2005 - September 6, 2005, Tianjin, China 作者: Liu H.; Liu H.; Liu H. 收藏 \| 浏览/下载：21/0 \| 提交时间：2013/03/25 Medical imaging has started to take advantage of digital technology opening the way for advanced medical imaging and teleradiology. Medical images however require large amounts of memory. At over 1 million bytes per image a typical hospital needs a staggering amount of memory storage (over one trillion bytes per year) and transmitting an image over a network (even the promised superhighway) could take minutes - too slow for interactive teleradiology. This calls for image compression to reduce significantly the amount of data needed to represent an image. Several compression techniques with different compression ratio have been developed. However the lossless techniques which allow for perfect reconstruction of the original images yield modest compression ratio while the techniques that yield higher compression ratio are lossy that is the original image is reconstructed only approximately Medical imaging poses the great challenge of having compression algorithms that are lossless (for diagnostic and legal reasons) and yet have high compression ratio for reduced storage and transmission time. To meet this challenge we are developing and studying some compression schemes which are either strictly lossless or diagnostically lossless taking advantage of the peculiarities of medical images and of the medical practice. In order to increase the Signal to-Noise Ratio (SNR) by exploitation of correlations within the source signal a method of combining differential pulse code modulation (DPCM) is presented.
	All-solid-stated laser controller design based on digital optical feedback (EI CONFERENCE) 会议论文 OAI收割 Lasers in Material Processing and Manufacturing II, November 10, 2004 - November 12, 2004, Beijing, China 作者: Liu L.; Wang J.-L.; Wang J.-L.; Liu L. 收藏 \| 浏览/下载：32/0 \| 提交时间：2013/03/25 The new design about a CW digital all-solid-stated LD pumped Nd:YVO 4 controller is introduced. The stable output power of this digital laser controller which adopts Digital Signal Processor(TMS320C31) is approximately 20mW. The whole system is composed of constant- current source protection circuit pulse-width modulation circuit Si-photo-detector and amplified circuit and Digital Signal Processor control system etc. In terms of error deviation Based on nonlinear control curves of LD power output by Si-photo-detector the region control can be obtained by means of the PID control algorithm in the software platform that is error amendment and high stability laser power output can be achieved. And the precision of temperature control can reduce from 0.2C to 0.04C. By adopted integral separated mode PID control algorithm the LD output power instability ( %) down to 2%. By way of adopting the new digital design the work to protect the laser diode including the continuous adjustable output power with high accuracy and stability is easily obtained. The internal-external modulation control of the laser power based on digital optical feedback can be accomplished with stable power output. At last the bringing reasons of noise are analyzed and the solving methods are put forward in this paper.