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A muon high-resolution pseudorange measurement method: Application to muon navigation in confined spaces

Chinese Journal of Aeronautics 2024年第4期37卷 391-404页

作者： Haoyang LI chunxi zhang Xingming FAN Longjie TIAN Tianqi LI Yang PANG Yanqiang YANG Institute of Optics and Electronics School of Instrumentation Science and Optoelectronics EngineeringBeihang UniversityBeijing 100191China Institute of High Energy Physics Chinese Academy of SciencesBeijing 100049China

Confined spaces such as polar regions, deep earth and deep ocean are crucial navigation scenarios where traditional navigation techniques have difficulty in obtaining external signals for positioning. The cosmic ray muons, which carry the spatial and energetic information, are easy to penetrate these confined spaces. Therefore, the unique muon characteristic provides a new perspective to estimate detector position, which can be considered using in confined spaces *** this paper, a well-developed theory of muon navigation is established by combining a muon pseudorange measurement method. Moreover, an Equivalent Velocity Calculation Model(EVCM)and a Muon Sequence Matching Technology(MSMT) are proposed. The first model corrects flight pseudorange error caused by the relativistic energy loss and the second technology compensates the random error in pseudorange measurement. Further, a series of simulations are performed to analyze the muon events number which can be received by detector in different scenarios with the variations of zenith angle, detector area, varied detector plates gap, and muon flight ***, the simulation results demonstrate that the muon navigation update rate every 10 minutes can reach 5.989 in confined spaces at 100 m, and further pseudorange error analysis indicates that the meter-level positioning accuracy can be acquired. Finally, we construct a muon coincidence measurement scheme and verify that the laws of the muon positioning system for high-energy muons are consistent with the simulation results.

关键词： Muon navigation Cosmic ray muons Muon detection technology Muon transmission technology Pseudorange measurement

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The first artificial Mn_4Ca-cluster mimicking the oxygen-evolving center in photosystem Ⅱ

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Science China(Life Sciences) 2015年第8期58卷 816-817页

作者： zhang chunxi Laboratory of Photochemistry Institute of Chemistry Chinese Academy of Sciences

The oxygen-evolving center （OEC） in photosystem Ⅱ（PSⅡ） of plants, algae and cyanobacteria, is a unique catalyst in nature to split water into O2, protons and electrons by using sun light. Because of broad fundamental interests and potential applications in artificial photosynthesis, the structure and properties of this unique catalyst have attracted extensive attention during the last two decades. Recent X-ray crystallographic studies of PSⅡ have revealed that the bio- logical OEC is comprised of a unique asymmetric Mn4Cacluster bound to protein groups [1,2] （Figure 1, left）. This biological catalyst serves as a blueprint for the development of efficient and cheap artificial catalysts for water-splitting reaction to overcome the bottleneck of entire field of artificial photosynthesis. However, it is a great challenge for chemists to synthesize the whole structure of the OEC in laboratory mainly due to the following reasons：（i） It is

关键词：人工模拟集群系统氧气生物催化剂人工光合作用 X-射线晶体学 OEC 光系统Ⅱ

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基于SOA光纤环形激光器的分布式声传感系统

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光通信技术 2024年第1期48卷 18-22页

作者：杨苏凡张春熹王夏霄北京航空航天大学仪器科学与光电工程学院北京100191

为了降低传统分布式声学传感器(DAS)系统复杂度并提高信噪比(SNR),提出了一种基于半导体光放大器的光纤环形激光器(SOA-FRL)的DAS系统。该系统用SOA-FRL取代了传统的DAS系统中的窄线宽激光器和脉冲调制器,实现了高稳定的光脉冲输出;采... 详细信息

为了降低传统分布式声学传感器(DAS)系统复杂度并提高信噪比(SNR),提出了一种基于半导体光放大器的光纤环形激光器(SOA-FRL)的DAS系统。该系统用SOA-FRL取代了传统的DAS系统中的窄线宽激光器和脉冲调制器,实现了高稳定的光脉冲输出;采用双脉冲外差探测方法,实现了精确的声信号探测和声源定位。实验结果表明:在频率为1 kHz、幅值为1.14 rad的声信号作用下,所提系统的解调SNR高达38.25 dB,空间分辨率为12 m。

关键词：分布式声传感半导体光放大器光纤环形激光器外差探测光纤传感

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A new milestone for photosynthesis

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National Science Review 2018年第4期5卷 444-445页

作者： chunxi zhang Tingyun Kuang Laboratory of Photochemistry Institute of Chemistry Chinese Academy of Sciences Laboratory of Photobiology Institute of BotanyChinese Academy of Sciences

The photosynthetic water-splitting reaction catalysed by the oxygen-evolving center(OEC)in the photosystem II of plants releases protons,electrons and dioxygen,which is one of the most important processes for energy and material conversions on *** is a Mn4Cacluster and cycles through five different states(Sn,n=0–4),wherein S0is the most reduced state,S1is the dark stable state and S2,S3and S4are intermediate

关键词： OEC A new milestone for photosynthesis

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Fast fine acquisition algorithm of GPS receiver aided by INS information

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Journal of Systems Engineering and Electronics 2011年第2期22卷 300-305页

作者： Lufeng Zhu chunxi zhang Zhiqiang Ma School of Instrumentation & Optoelectronics Engineering Beihang University Beijing 100191 P. R. China

Acquisition time of global position system （GPS） receiver, which is the main factor contributes to time to first fix （TTFF）, can be shortened by estimating the Doppler frequency shift through external inertial navigation system （INS） information and almanac data and reducing the searching area. The traditional fast acquisition is analyzed, the fast acquisition of the GPS receiver aided is presented by INS information, and the signal is fine captured by spectrum zooming. Then the algorithm is simulated by sampled GPS intermediate frequency （IF） signal and the result verifies that this acquisition can dramatically improve the capability of GPS receiver and reduce its acquisition time.

关键词： inertial navigation system (INS) aid spectrum zooming acquisition time global position system (GPS) receiver.

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Self-alignment of full skewed RSINS: observability analysis and full-observable Kalman filter

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Journal of Systems Engineering and Electronics 2014年第1期25卷 104-114页

作者： Lailiang Song chunxi zhang Jiazhen Lu School of Instrument Science and Opto-electronics Engineering Beihang University

Traditional orthogonal strapdown inertial navigation sys-tem （SINS） cannot achieve satisfactory self-alignment accuracy in the stationary base： taking more than 5 minutes and al the iner-tial sensors biases cannot get ful observability except the up-axis accelerometer. However, the ful skewed redundant SINS （RSINS） can not only enhance the reliability of the system, but also improve the accuracy of the system, such as the initial alignment. Firstly, the observability of the system state includes attitude errors and al the inertial sensors biases are analyzed with the global perspective method： any three gyroscopes and three accelerometers can be assembled into an independent subordinate SINS （sub-SINS）;the system state can be uniquely confirmed by the coupling connec-tions of al the sub-SINSs;the attitude errors and random constant biases of al the inertial sensors are observable. However, the ran-dom noises of the inertial sensors are not taken into account in the above analyzing process. Secondly, the ful-observable Kalman filter which can be applied to the actual RSINS containing random noises is established; the system state includes the position, ve-locity, attitude errors of al the sub-SINSs and the random constant biases of the redundant inertial sensors. At last, the initial self-alignment process of a typical four-redundancy ful skewed RSINS is simulated： the horizontal attitudes （pitch, rol ） errors and yaw error can be exactly evaluated within 80 s and 100 s respectively, while the random constant biases of gyroscopes and accelero-meters can be precisely evaluated within 120 s. For the ful skewed RSINS, the self-alignment accuracy is greatly improved, mean-while the self-alignment time is widely shortened.

关键词： global perspective redundant strapdown inertial navigation system (RSINS) self-alignment observability analysis,Kalman filter.

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Scalable and quantitative contention generation for performance evaluation on OLTP databases

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Frontiers of Computer Science 2023年第2期17卷 15-31页

作者： chunxi zhang Yuming LI Rong zhang Weining QIAN Aoying ZHOU School of Data Science and Engineering East China Normal UniversityShanghai 200062China

Massive scale of transactions with critical requirements become popular for emerging businesses,especially in *** of the most representative applications is the promotional event running on Alibaba's platform on some special dates,widely expected by global *** we have achieved significant progress in improving the scalability of transactional database systems(OLTP),the presence of contention operations in workloads is still one of the fundamental obstacles to performance *** reason is that the overhead of managing conflict transactions with concurrency control mechanisms is proportional to the amount of *** a consequence,generating contented workloads is urgent to evaluate performance of modern OLTP database *** we have kinds of standard benchmarks which provide some ways in simulating contentions,e.g.,skew distribution control of transactions,they can not control the generation of contention quantitatively;even worse,the simulation effectiveness of these methods is affected by the scale of *** in this paper we design a scalable quantitative contention generation method with fine contention granularity *** conduct a comprehensive set of experiments on popular opensourced DBMSs compared with the latest contention simulation method to demonstrate the effectiveness of our generation work.

关键词： high contention OLTP database performance evaluation database benchmarking

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Artificial Mn4-oxido complexes mimic the oxygen-evolving center in photosynthesis

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Science Bulletin 2017年第9期62卷 665-668页

作者： Wenyan Chang Changhui Chen Hongxing Dong chunxi zhang Polymer Materials Research Center College of Materials Science and Chemical Engineering Harbin Engineering University Harbin 15000 I China Laboratory of Photochemistry Institute of Chemistry Chinese Academy of Sciences Beijing 100190 China University of Chinese Academy of Sciences Beijing 100049 China

The understanding of the structure-function relationship of the oxygen-evolving center(OEC), a Mn_4 Cacluster, in photosystem II is impeded mainly due to the complexity of the protein environment and lack of rational chemical models as a reference. In this study, two novel Mn_4-oxido complexes have been synthesized and characterized, in which the peripheral ligands of the [Mn_4~Ⅲ] core are provided by eight μ_2-carboxylate groups and two neutral terminal ligands(pyridine or isoquinoline). This type of peripheral ligation is very similar to the Mn_4Ca-oxide model complexes recently reported to mimic the OEC. The new Mn_4-oxide complex can catalyze the oxygen-evolving reaction in the presence of Bu^tOOH as an oxidant. The structure and redox properties comparison of the Mn_4-oxido and Mn_4Ca-oxido complexes provide important clues to understanding the functional role of Ca in the OEC in natural photosynthesis, and develop more efficient artificial catalysts for the water-splitting reaction in the future.

关键词： Natural photosynthesis Artificial photosynthesis Oxygen-evolving reaction Mn4Ca-cluster Mn4-oxido complex

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Noise decomposition and parameter optimization method for high sensitivity fiber optic gyroscope

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Science China(Technological Sciences) 2015年第6期58卷 1118-1124页

作者： TENG Fei JIN Jing zhang ZuChen DU ShiSen SONG NingFang zhang chunxi School of Instrument Science and Opto-electronics Engineering Beihang University (BUAA) Technical Institute of Physics and Chemistry of CAS

A novel random walk coefficient(RWC) model of the interferometric fiber optic gyroscope(IFOG) to decompose fundamental noise sources, namely the shot noise, the excess noise, the thermal noise, and the detection circuit noise, from the overall noise was developed. The coefficients of the model were extracted from the measured RWC instead of by calculating the accurate IFOG parameters, which is simpler and more accurate. The correctness and the accuracy of the model were verified by experiments. Using this model, the RWC of the experimental IFOG was predicted and the quantitative contributions of the noise sources were determined. According to the predicted results, the parameters of the IFOG were optimized. Finally, based on the model, a noise decomposition and parameter optimization method was proposed for high sensitivity IFOG design.

关键词： fiber optic gyroscopes noise decomposition random walk parameter optimization

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Effect of ^(60)Co-gamma radiation on the random walk error of interferometric fiber optic gyroscopes

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Science China(Technological Sciences) 2010年第11期53卷 3056-3060页

作者： JIN Jing WANG XueQin SONG NingFang zhang chunxi School of Instrument Science and Optic-electronics Engineering Beihang UniversityBeijing 100191China

Two 60Co-gamma radiation experiments were launched to explore the radiation effect on optical components and interferometric fiber optic gyroscope (IFOG). In optical components radiation experiment, the result showed that polarization-maintaining (PM) fiber coil loss was the most affected parameter in all the RWC (random walk coefficient) related parameters, compared with the weak sensitivity of other components parameters. In the IFOG radiation experiment, the RWC performance degradation was found to be almost due to an increase of the PM fiber attenuation. Based on the experiment result, a RWC prediction model in radiation, which is obtained by embedding PM fiber loss expression into the RWC model, was built following a power law of dose and dose rate. An IFOG RWC in space radiation environment was predicted from radiation dose and dose rate by the RWC prediction model. This RWC value calculated from test data is fully accorded to the RWC value predicted from radiation dose.

关键词： fiber optic gyroscope radiation effects random walk fiber loss

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