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A universal adaptive vector quantization algorithm for space-borne SAR raw data

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Science china(Information Sciences) 2012年第6期55卷 1280-1289页

作者： qi HaiMing 1,2.HUA Bin 1,2.LI Xin 1,2.{4. {2. 1 & HONG Wen 1,2.1 institute of electronics,chinese Academy of Sciences,beijing 100190,china 2.National Key Laboratory of Microwave Imaging Technology,beijing 100190,china 1. institute of electronics Chinese Academy of Sciences Beijing 100190 China2. National Key Laboratory of Microwave Imaging Technology Beijing 100190 China

Codebook of conventional VQ cannot be generally used and needs real time onboard updating,which is hard to implement in spaceborne SAR *** order to solve this problem,this paper analyses the characteristic of space-borne SAR raw data firstly,and then utilizes the distortion function of multidimensional space as criterion,and finally the adaptive code book design algorithm is proposed according to the joint probability density function of the input ***,the feasibility of the new algorithm in cascade with entropy coding and the robustness of the algorithm when error occurs during transmission are analysed based on the encoding and decoding *** results of real data show that codebook deriving from the new algorithm can be generally used and designed off-line,which makes VQ a practical algorithm for space-borne SAR raw data compression.

关键词： synthetic aperture radar (SAR) compression raw data block adaptive quantization (BAQ) vector quantization (VQ)

Damage evolution of rock-encased-backfill structure under stepwise cyclic triaxial loading

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第2期16卷 597-615页

作者： Xin yu yuye Tan {2. Song John Kemeny Shengwen qi Bowen Zheng Songfeng Guo Key Laboratory of Shale Gas and Geoengineering Institute of Geology and GeophysicsChinese Academy of SciencesBeijing100089China Innovation Academy for Earth Science Chinese Academy of SciencesBeijing100089China University of chinese Academy of Sciences Beijing100049China School of Civil and Resources Engineering University of Science and Technology BeijingBeijing100083China Key Laboratory of High-Efficient Mining and Safety of Metal Mines(Ministry of Education of china) University of Science and Technology BeijingBeijing100083China Department of Mining and Geological Engineering University of ArizonaTucsonAZ86721USA

Rock-encased-backfill(RB)structures are common in underground mining,for example in the cut-andfill and stoping *** understand the effects of cyclic excavation and blasting activities on the damage of these RB structures,a series of triaxial stepwise-increasing-amplitude cyclic loading experiments was conducted with cylindrical RB specimens(rock on outside,backfill on inside)with different volume fractions of rock(VF=0.4.,0.61,0.73,and 0.84.,confining pressures(0,6,9,and 12.MPa),and cyclic loading rates(2.0,300,4.0,and 500 N/s).The damage evolution and meso-crack formation during the cyclic tests were analyzed with results from stress-strain hysteresis loops,acoustic emission events,and post-failure X-ray 3D fracture *** results showed significant differences between cyclic and monotonic loadings of RB specimens,particularly with regard to the generation of shear microcracks,the development of stress memory and strain hardening,and the contact forces and associated friction that develops along the rock-backfill *** important finding is that as a function of the number of cycles,the elastic strain increases linearly and the dissipated energy increases ***,compared with monotonic loading,the cyclic strain hardening characteristics are more sensitive to rising confining pressures during the initial compaction *** finding is that compared with monotonic loading,more shear microcracks are generated during every reloading stage,but these microcracks tend to be dispersed and lessen the likelihood of large shear fracture *** transition from elastic to plastic behavior varies depending on the parameters of each test(confinement,volume fraction,and cyclic rate),and an interesting finding was that the transformation to plastic behavior is significantly lower under the conditions of 0.73 rock volume fraction,4.0 N/s cyclic loading rate,and 9 MPa *** the findings have important practical implications on t

关键词： Rock and backfill Triaxial cyclic loading Volume fraction Damage evolution 3D visualization

A study of spaceborne SAR raw data compression error based on a statistical model of quantization interval transfer probability

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Science china(Information Sciences) 2010年第11期53卷 2352-2362页

作者： LI Xin1,2.3*, qi HaiMing1,2., HUA Bin1,2.3, LEI Hong1 & {4. {2.1 1institute of electronics, chinese Academy of Sciences, beijing 100190, china 2.he National Key Laboratory of Microwave Imaging Technology, beijing 100190, china 3Graduate University, chinese Academy of Sciences, beijing 100039, china 1. institute of electronics Chinese Academy of Sciences Beijing 100190 China2. The National Key Laboratory of Microwave Imaging Technology Beijing 100190 China3. Chinese Academy of Sciences Graduate University Beijing 100039 China

SAR raw data signal to noise ratio (SNR) after compression is of great importance since the choice of compression ratio is dependent on it during SAR system design and application analysis. The signal to quantization noise ratio (SQNR) generally used may not precisely indicate the relationship between signal and noise. Considering the thermal noise, a statistical model of quantization interval transfer probability is proposed in this paper. SNR mapping between SAR raw data before analog to digital converter (ADC) and after block adaptive quantization (BAQ) over the whole set of saturation degree is obtained using this model. When the power of echo is small with low SNR, after 1, 2. 3 or 4.bits BAQ compression, SNR has tiny difference among the four compression levels. When the power of the echo is medium with higher SNR, the SNR degradation after BAQ is about 5 dB with each bit decreasing from 4.bits. If voltage of the echo is higher than the clipping point of ADC, SNR after ADC and BAQ degrades stepwise. The higher the saturation degree of SAR raw data, the worse the SNR is. Simulated Gaussian data and real SAR raw data are used to verify the theoretical results, which are useful in the choice of BAQ compression ratio and further application analysis.

关键词： SAR raw data compression SNR saturation

Anti-saturation block adaptive quantization algorithm for SAR raw data compression over the whole set of saturation degrees

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Progress in Natural Science:Materials International 2009年第8期19卷 1003-1009页

作者： Haiming qi , weidong {2. institute of {4., chinese Academy of Sciences, beijing 100190, china [a]institute of electronics Chinese Academy of Sciences Beijing 100190 China

In order to improve the performance of block adaptive quantization (BAQ) when the output of the analog to digital converter (ADC) is saturated, this paper proposes an anti-saturation BAQ algorithm. First, the concept of the standard deviation of the output signal (SDOS) of the ADC is proposed. Also, unlike traditional normalization processing, SDOS is used and the mapping between SDOS and the average signal magnitude is deduced. Second, the saturation term is introduced to the Lloyd–Max quantizer and an optimal non-uniform scalar quantizer for saturated SAR raw data quantization is proposed. After this, the implementation scheme for the proposed algorithm using an FPGA is analyzed in detail. Third, the relationships among the saturation degree of the signal, the peak-topeak value of the ADC, standard deviation of the input and output signal of the ADC and the average signal magnitude are deduced. Based on these relationships, a power compensation decoder is designed for encoding. Numerical experiment results based on ERS-1 and the simulated data show that the performance of the proposed algorithm is better than that of BAQ.

关键词： Synthetic aperture radar (SAR) Raw data compression Block adaptive quantization (BAQ) Anti-saturation

N_2. emissions from agricultural soils in the North china Plain: the effect of chemical nitrogen fertilizer and organic manure

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Journal of Environmental Sciences 2000年第4期12卷 463-468页

作者： DONG yun\|she 1,2.3 , Dieter Scharffe 2. Manfred Domroes 3, qi yu chun 1, ZHANG Shen 1 (1. institute of Geographic Sciences and Natural Resources Research, chinese Academy of Sciences, beijing 100101, china E\|mail: dongys@*** 2. M 中科院地理科学与资源所北京 1 0 0 1 0 Max- Planck-institute of Chemistry 德国 Mainz 550 2 0 Mainz University 德国 Mainz 550 99

An enclosed chamber technique was used to measure N 2. emissions from intensively agricultural soils of the North china Plain during the periods of 1995—1996 and 1997—1998, to reflect distinct components of winter wheat and summer maize growing seasons. The results showed that the continuous application of fertilizer in agricultural soils increased N\-2. emissions by a factor of 2..1—2..1, the calculated annual chemical N fertilizer\|transformed N\-2.\|N emissions was 0.67%. Our results indicated that the application of organic manure also had a significant influence on soil N 2. emissions, which combined with the use of chemical N increased about 2.% in a year. It was calculated that there were about 0.11% N of organic manure transformed as N 2. N. Annual mean N 2. emission from our study area of fertilized soils was estimated to be 57.1 μgN 2./(m 2.h). A weak correlation was also found between N 2. emissions and soil available nitrogen content NH + 4.

关键词： N_2. emissions the North china Plain agricultural soils chemical nitrogen organic manure

The properties of halo structure for ^(17)B

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Science china(Physics,Mechanics & Astronomy) 2008年第7期51卷 781-787页

作者： HU ZhengGuo1, WANG Meng1, XU HuShan1, SUN Zhiyu1, WANG JianSong1, XIAO Guoqing1, ZHAN WenLong1, XIAO ZhiGang1, MAO RuiShi1,2. LI Chen1, ZHANG XueYing1,2. ZHANG HongBin1, ZHAO TieCheng1, XU ZhiGuo1, WANG yue1,2. CHEN RuoFu1,2. HUANG TianHeng1,2. FU Fen1,2. GAO qi1,2. HAN JianLong1,2. ZHANG XueHeng1,2. ZHENG Chuan1,2. yu yuHong1,2.& GUO ZhongYan1 1 institute of Modern Physics, chinese Academy of Sciences, Lanzhou 730000, china 2.Graduate University of the chinese Academy of Sciences, beijing 10004., china 1. institute of Modern Physics Chinese Academy of Sciences Lanzhou 730000 China 2. Graduate University of the chinese Academy of Sciences Beijing 100049 China

The total reaction cross section (172.±93 mb) of 17B at the energy of 4..7 A MeV on C target has been measured by using the transmission method at the Radioactive Ion Beam Line in Lanzhou (RIBLL). Assuming 17B consists of a core 15B plus two halo neutrons,the total cross section of 17B on C target was calculated with the zero-range Glauber model,where double Gaussian density distributions and Gaussian plus HO density distributions were used. It can fit the experimental data very well. The characteristic of halo structure for 17B was found with a large diffusion of the neutrons density distribution.

关键词： total cross section density distribution Glauber model the characteristic of halo structure

Human parthenogenetic embryonic stem cells:one potential resource for cell therapy

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Science china(Life Sciences) 2009年第7期52卷 599-602页

作者： HAO Jie1,2.ZHU WanWan1,SHENG Chao1,yu Yang1,ZHOU qi1 1 State Key Laboratory of Reproductive Biology,{2. of Zoology,{4. 100101,china 2.Graduate School,chinese Academy of Sciences,{4. 10004.,china State Key Laboratory of Reproductive Biology Institute of Zoology Beijing 100101 China Graduate School Chinese Academy of Sciences Beijing 100049 China

Pluripotent stem cells derived from somatic cells through such processes as nuclear transfer or induced pluripotent stem(iPS) cells present an important model for biomedical research and provide potential resources for cell replacement ***,the overall efficiency of the conversional nuclear transfer is very low and the safety issue remains a major concern for iPS *** stem cells(ESCs) generated from parthenogenetic embryos are one attractive alternative as a source of histocompatible cells and tissues for cell *** studies on human parthenogenetic embryonic stem cells(hPG ESCs) have revealed that these ESCs are very similar to the hESCs derived from IVF or in vivo produced blastocysts in gene expression and other characteristics,but full differentiation and development potential of these hPG ESCs have to be further investigated before clinical research and therapeutic *** generate various pluripotent stem cells,diverse reprogramming techniques and approaches will be developed and *** may help elucidate the fundamental mechanisms underlying reprogramming and stem cell biology,and ultimately benefit cell therapy and regenerative medicine.

关键词： human parthenogenetic embryonic stem cell therapeutic cloning induced differentiation imprinting heterozygosis cell therapy

Precipitation Pulses and Soil CO_2.Emission in Desert Shrubland of Artemisia ordosica on the Ordos Plateau of Inner Mongolia,china

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Pedosphere 2009年第6期19卷 799-807页

作者： JIN Zhao DONG yun-She qi yu-Chun M. DOMROES institute of Geographical Sciences and Natural Resources Research Chinese Academy of Sciences Beijing 100101 （China） State Key Laboratory of Loess and Quaternary Geology Institute of Earth Environment Chinese Academy of Sciences Xi＇an 710075 （China） institute of Geography Mainz University Mainz 55099 （Germany）

Precipitation is the major driver of ecosystem functions and processes in semiarid and arid regions. In such waterlimited ecosystems, pulsed water inputs directly control the belowground processes through a series of soil drying and rewetting cycles. To investigate the effects of sporadic addition of water on soil CO2.effux, an artificial precipitation event （3 mm） was applied to a desert shrub ecosystem in the Mu Us Sand Land of the Ordos Plateau in china. Soil respiration rate increased 2.8 4.1 times immediately after adding water in the field, and then it returned to background level within 4. h. During the experiment, soil CO2.production was between 2.04..0 and 7 383.0 mg m^-2. In the shrubland, soil respiration responses showed spatial variations, having stronger pulse effects beneath the shrubs than in the interplant spaces. The spatial variation of the soil respiration responses was closely related with the heterogeneity of soil substrate availability. Apart from precipitation, soil organic carbon and total nitrogen pool were also identified as determinants of soil CO2.loss in desert ecosystems.

关键词： desert shrub ecosystem Mu Us sand land soil respiration response water addition

Simulating the GRF of Humanoid Robot Vertical Jumping Using a Simplified Model with a Foot Structure for Foot Design

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Journal of Bionic Engineering 2024年第1期21卷 112-125页

作者： Chuanku Yi Xuechao Chen yu Zhang Zhangguo yu Haoxiang {2. Yaliang Liu {2.ang Huang School of Mechatronical Engineering Beijing Institute of TechnologyZizhuyaunHaidianBeijing 100081China beijing Advanced Innovation Center for Intelligent Robots and Systems Beijing Institute of Tec

There are many theories and tools for human or robot motion simulation,but most of them require complex *** LNZN model(a simplified model named by the proposers)simplifies the human model and facilitates simulation of the Ground Reaction Force(GRF)of body landing by spring damping model and ignoring joint rotation movements,which can reduce the amount of computation *** this paper,the LNZN model of human running is selected as the basis and is modified to obtain the LNZN model of a robot,which expands the application of the LNZN *** to the structure of the human foot,a foot structure is then added to the simplified model to reduce the *** also applied driving forces to the new model to simulate the whole high jump motion of the robot to expand the functions of the LNZN *** obtained GRF data were anastomotic to the actual experimental *** addition,the effects of variables,such as the mass,hardness,and damping,of the foot on the GRF at the moment of landing were also ***,based on the guidelines obtained for the design of the robot’s foot structure,we fabricated new robot’s feet and installed them on the actual robot and achieved a better cushioning effect than the original foot in experiments.

关键词： LNZN model-GRF simulation Humanoid foot structure Foot parameters