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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,yu weidong 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 institute of electronics Chinese Academy of Sciences Beijing China National Key Laboratory of Microwave Imaging Technology Beijing 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)

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 yu institute of electronics, chinese academy of sciences, beijing 100190, china 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

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 weidong 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=0.48,0.61,0.73,and 0.84),confining pressures(0,6,9,and 12 MPa),and cyclic loading rates(200,300,400,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,400 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 & yu weidong1 1institute of electronics, chinese academy of sciences, beijing 100190, china 2The National Key Laboratory of Microwave Imaging Technology, beijing 100190, china 3Graduate University, chinese academy of sciences, beijing 100039, china institute of electronics Chinese Academy of Sciences Beijing China The National Key Laboratory of Microwave Imaging Technology Beijing China chinese academy of sciences Graduate University Beijing 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

160 km/h动力集中动车组车轮旋修优化方案研究

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铁道机车车辆 2024年第4期44卷 144-150页

作者：肖齐于卫东樊立新石邹亮中国铁道科学研究院集团有限公司机车车辆研究所北京100081 中国铁路乌鲁木齐局集团有限公司乌鲁木齐车辆段乌鲁木齐830023

文中以提升动力集中动车组车轮旋修经济性为目标,开展动力车、拖车/控制车车轮旋修优化方案研究。文中利用TPDS轨旁监测数据和不落轮车床测量数据,耦合分析了车轮踏面伤损现状,提出了适合机辆一体化检修方案的车轮旋修模型,解决动力车... 详细信息

文中以提升动力集中动车组车轮旋修经济性为目标,开展动力车、拖车/控制车车轮旋修优化方案研究。文中利用TPDS轨旁监测数据和不落轮车床测量数据,耦合分析了车轮踏面伤损现状,提出了适合机辆一体化检修方案的车轮旋修模型,解决动力车部分失修、拖车/控制车部分过度修和旋修周期不匹配等问题,从而延长车轮旋修周期,提升动力集中动车组运用检修的安全性、经济性。

关键词：动力集中动车组车轮旋修车辆运行品质轨边动态监测系统(TPDS) 踏面损伤

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动车组轮轨一体化智能维修决策方案

中国铁路 2024年第7期 188-194页

作者：田光荣于卫东朱韶光石雯肖齐中国铁道科学研究院集团有限公司机车车辆研究所北京100081 北京纵横机电科技有限公司北京100094

轮轨匹配质量直接影响动车组运行安全和舒适性。针对服役过程中发生的车载异常振动故障源定位不清及维修决策导向难等问题,依托智能高铁2.0科技攻关项目,基于车载振动数据、轨旁监测检测数据及线路特征数据等多源数据融合,研究提出基于... 详细信息

轮轨匹配质量直接影响动车组运行安全和舒适性。针对服役过程中发生的车载异常振动故障源定位不清及维修决策导向难等问题,依托智能高铁2.0科技攻关项目,基于车载振动数据、轨旁监测检测数据及线路特征数据等多源数据融合,研究提出基于决策树和随机森林方法的全域条件下车轮和钢轨一体化智能运维策略技术方案,为指导现场开展车轮旋换轮处置或钢轨打磨奠定了基础。

关键词：智能高铁轮轨维修一体化多源数据融合决策树随机森林

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Piecewise linear mapping algorithm for SAR raw data compression

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Science in china(Series F) 2008年第12期51卷 2126-2134页

作者： qi HaiMing yu weidong CHEN Xi institute of electronics Chinese Academy of Sciences Beijing 100080 China

When the saturation degree （SD） of space-borne SAR raw data is high, the performance of conventional block adaptive quantization （BAQ） deteriorates obviously. In order to overcome the drawback, this paper studies the mapping between the average signal magnitude （ASM） and the standard deviation of the input signal （SDIS） to the A/D from the original reference. Then, it points out the mistake of the mapping and introduces the concept of the standard deviation of the output signal （SDOS） from the A/D. After that, this paper educes the mapping between the ASM and SDOS from the A/D. Monte-Carlo experiment shows that none of the above two mappings is the optimal in the whole set of SD. Thus, this paper proposes the concept of piecewise linear mapping and the searching algorithm in the whole set of SD. According to the linear part, this paper gives the certification and analytical value of k and for nonlinear part, and utilizes the searching algorithm mentioned above to search the corresponding value of k. Experimental results based on simulated data and real data show that the performance of new algorithm is better than conventional BAQ when raw data is in heavy SD.

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

ADAPTIVE NULL PHASE-SHIFT POLARIZATION FILTER

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Journal of electronics(china) 2007年第3期24卷 321-325页

作者： qi Haiming yu weidong Dong qian Zhang Huansheng institute of electronics Chinese Academy of Sciences Beijing 100080 China Graduate University of chinese academy of sciences Beijing 100039 China

The estimation of clutter polarization is significant in virtual polarization filtering. This paper proposes variable step size Least Mean Square error (LMS) algorithm to estimate clutter po-larization. The adaptive recursive function is set up based on double polarization receiving signal model. By choosing desired response signal properly,the received data are estimated. The result of estimation is used for Null Phase-Shift instantaneous Polarization Filter (NPSPF) design and target’s amplitude and phase compensation. Algorithm’s tracking performance is discussed in detail. The simulation results are consistent with the above analysis,and the clutter suppression is effective.

关键词： Polarization Adaptive Filtering Detection

Systematic Characterization of Long Non-Coding RNAs and Their Responses to Drought Stress in Dongxiang Wild Rice

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Rice science 2020年第1期27卷 21-31页

作者： qi weidong CHEN Hongping YANG Zuozhen HU Biaolin LUO Xiangdong AI Bing LUO yuan HUANG yu XIE Jiankun ZHANG Fantao College of Life sciences Jiangxi Normal UniversityNanchang 330022China Rice Research institute Jiangxi Academy of Agricultural SciencesNanchang 330200China Cipher Gene Limited Liability Company Beijing 100080China

Long non-coding RNAs(lncRNAs) play important roles in response to various biotic and abiotic stresses. So far, systematic identification and characterization of lncRNAs have been reported in a few model plant species and major crops, but their roles in abiotic stress response have not yet been reported in common wild rice(Oryza rufipogon). Dongxiang wild rice(DXWR) possesses a high degree of drought resistance and has been well recognized as a precious genetic resource for drought resistant rice breeding. We presented the reference catalog of 1 655 novel lncRNA transcripts in DXWR using strand-specific RNA sequencing and bioinformatics approaches. Meanwhile, a total of 1092 lncRNAs were determined as differentially expressed lncRNAs under drought stress. Quantitative real-time PCR results exhibited a high concordance with RNA sequencing data, which confirmed that the expression patterns of lncRNAs based on RNA sequencing were highly reliable. Furthermore, 8 711 transcripts were predicted as target genes of the differentially expressed lncRNAs. Functional annotation analysis based on Gene Ontology and Kyoto Encyclopedia of Genes and Genomes databases showed that the target genes were significantly enriched in cellular and metabolic processes, cell part, binding and plant hormone signal transduction, as well as many other terms related to abiotic stress resistance. These results expanded our understanding of lncRNA biology and provided candidate regulators for genetic improvement of drought resistance in rice cultivars.

关键词： Dongxiang wild rice drought stress long non-coding RNA systematic characterization