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Impacts of inter-satellite links on the ECOM model performance for BDS-3 MEO satellites

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Satellite Navigation 2024年第1期5卷 140-154页

作者： Chao Yang Jing Guo Xiaolong Xu longyu Wang Qile Zhao GNSS Research Center Wuhan UniversityNo.129 Luoyu RoadWuhan430079China

Inter-satellite link(ISL)plays an essential role in current and future Global Navigation Satellite System(GNSS).In this study,we investigate the impact of ISL observations on precise orbit determination for BeiDou-3 Navigation Satellite System(BDS-3)Medium Earth Orbit(MEO)satellites based on different Extended CODE Orbit Models(ECOM).Thanks to the better observation geometry of the Ka-band ISL data compared to the L-band data for BDS-3 MEO satellites,the ISL solution substantially reduces Orbit Boundary Discontinuity(OBD)errors,except for C30,which suffers from unstable Ka-band hardware *** the external quality analysis,ISL significantly enhances the reliability of the orbit of MEO satellites manufactured by the China Academy of Space Technology(CAST).The standard deviation(STD)of the satellite laser ranging(SLR)residuals is approximately 2.5 cm,and the root mean square(RMS)is reduced by 10–23%compared to L-band ***,the Sun-elongation angle dependent systematic error in SLR residuals nearly vanishes based on the reduced 5-parameter ECOM(ECOM1)or extended 7-parameter ECOM(ECOM2)with ISL *** is because the ISL reduces the correlation between state parameters and solar radiation pressure(SRP)parameters as well as those among SRP parameters,leading to a more accurate estimation of both orbit and SRP perturbations,particularly those along B *** confirms that the deficiency of the SRP models for BDS-3 CAST satellites can be compensated by using better observation geometry from ISL *** the other hand,for the satellite manufactured by Shanghai Engineering Center for Microsatellites(SECM),the ISL allows for a more accurate estimation of the Bc_(1)parameter in the ECOM1 *** only reduces linear systematic error,possibly because the impact generated by the satellite bus cannot be entirely absorbed by the B-direction parameters.

关键词： BDS-3 MEO Inter-satellite link Solar radiation pressure ECOM

Study on Pseudolite System for BeiDou Based on Dynamic and Independent Aircrafts Configuration

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Study on Pseudolite System for BeiDou Based on Dynamic and I...

Laser ablation mechanism and performance of glass fiber-reinforced phenolic composites:An experimental study and dual-scale modelling

第四届中国卫星导航学术年会

作者： Guohua Kang longyu tan Bing Hua Fengying Zheng Academy of Frontier Science NanJing University of Aeronautics and Astronautics College of Automation Engineering NanJing University of Aeronautics and Astronautics

This paper presents a pseudolite system for BeiDou based on dynamic and independent aircrafts configuration. Firstly, high-altitude and long-endurance unmanned aerial vehicles and airships are needed to obtain the best configuration by analyzing GDOP. Then aiming at the pseudolites’ positioning, a new integrated scheme was proposed, where distance between two aircrafts is utilized to improve the positioning accuracy. Simulation results show that GDOP is less than 3.5 and position precision of the pseudolite is 1.2m in the users’ area .The pseudolite system is able to provide moderate navigation service, when BeiDou position system is unavailable to users.

关键词： pseudolite BeiDou position system dynamic configuration integrated position

来源： cnki会议评论

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Chinese Journal of Aeronautics 2024年第8期37卷 470-485页

作者： Ran BI Pengfei SHEN longyu ZHU Zhengzheng MA Chuyang LUO Yongfeng LI Lijian PAN Shanghai Key Laboratory of Lightweight Composite Donghua UniversityShanghai 201620China Shanghai High Performance Fibers and Composites Center(Province-Ministry Joint) Center for Civil Aviation CompositesDonghua UniversityShanghai 201620China AVIC Composite Corporation Ltd Beijing 101300China

Both experimental and simulation approaches were employed to investigate the laser ablation mechanism and performances of Glass Fiber Reinforced Phenolic Composites(GFRP).During the ablation process,the difference in thermal conductivities of the glass fibers and the resin matrix as well as their discrepant physical and chemical reactions form a conical ablation *** formation of a residual carbon layer effectively mitigates the ablation rate in the thickness direction.A higher power density results in a faster ablation rate,while a longer irradiation time leads to a larger ablation pit *** account for the variation in thermal conductivity between the fiber and resin,a macro-mesoscale model was developed to differentiate the matrix from the fiber *** element analysis revealed that laser irradiation leads to phenolic decomposition,glass fiber melting vaporization,and residual carbon skeleton *** dual-scale model exhibits precise prediction capabilities concerning the laser ablation process of GFRP,and its accuracy is confirmed through the comparison of simulation and experimental results for the GFRP laser ablation *** model provides a feasible method for performance evaluation and lifetime prediction of GFRP subjected to continuous wave laser irradiation.

关键词： Polymer-matrix composites Continuous-wave laser Microstructural analysis Ablation mechanism Finite element method

A novel molybdenite depressant for efficient selective flotation separation of chalcopyrite and molybdenite

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International Journal of Mining Science and Technology 2024年第8期34卷 1179-1196页

作者： Mengyao Qi Weijun Peng Wei Wang Yijun Cao longyu Zhang Yukun Huang School of Chemical Engineering Zhengzhou UniversityZhengzhou 450001China Zhongyuan Critical Metals Laboratory Zhengzhou UniversityZhengzhou 450001China The Key Lab of Critical Metals Minerals Supernormal Enrichment and Extraction Ministry of EducationZhengzhou 450001China

A novel small molecule depressant(M-DEP)was used to separate chalcopyrite and molybdenite via *** results showed that M-DEP had an excellent selective depression on molybdenite,while had little effect on the flotation of *** adsorption capacity of M-DEP on the surface of molybdenite was greater than that on chalcopyrite *** adsorption of M-DEP reduced the floatability of molybdenite and had less effect on the floatability of chalcopyrite,which was due to its different adsorption modes on the surface of the two ***,the interaction between chalcopyrite and M-DEP was mainly chemical interaction,and almost all of the adsorbed M-DEP molecules were removed and replaced by sodium butyl xanthate(SBX).By contrast,hydrophobic interaction was the main way in which M-DEP was adsorbed on the molybdenite surface with little chemical interaction,which was less interfered by SBX ***,M-DEP had a super selective depression on *** study provided a novel depressant and approach for the deep separation of chalcopyrite and molybdenite via flotation.

关键词： Novel molecule depressant Molybdenite Chalcopyrite Flotation separation Selective depression

First identification of the oxazolidinone/phenicol resistance gene optrA in Streptococcus pluranimalium worldwide

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Journal of Integrative Agriculture 2024年第2期23卷 731-734页

作者： Kuan Zhao longyu Zhou Shixia Zhang Wanjiang Zhang Yao Zhu College of Veterinary Medicine Hebei Agricultural UniversityBaoding 071001China State Key Laboratory for Animal Disease Control and Prevention Harbin Veterinary Research InstituteChinese Academy of Agricultural SciencesHarbin 150069China College of Veterinary Medicine Xinjiang Agricultural UniversityUrumqi 830052China

Oxazolidinones are highly effective antimicrobial agents for the treatment of serious infections caused by Gram-positive organisms,including methicillin-resistant Staphylococcus aureus(MRSA),vancomycin-resistant enterococci(VRE),multidrug-resistant(MDR)pneumococci and MDR mycobacteria(Brenciani et al.2022).However,the emergence and prevalence of acquired oxazolidinone resistance genes.

关键词： resistance prevalence

Microseismic observations reveal that internal waves intensify seabed methane release

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Science China Earth Sciences 2024年第10期67卷 3186-3203页

作者： Zhaoyang TIAN Yonggang JIA Junjiang ZHU Tian CHEN Hui WANG Chunsheng JI Chengyu LIU longyu LU Manchao HE Shandong Provincial Key Laboratory of Marine Environment and Geological Engineering Ocean University of ChinaQingdao 266100China Frontiers Science Center for Deep Ocean Multispheres and Earth System Key Lab of Submarine Geosciences and Prospecting TechniquesMOE and College of Marine GeosciencesOcean University of ChinaQingdao 266100China Guangzhou Marine Geological Survey China Geological SurveyGuangzhou 511458China Shandong Earthquake Agency Jinan 250014China State Key Laboratory for Tunnel Engineering China University of Mining and Technology(Beijing)Beijing 100083China

Internal waves transport material and energy from the upper water column to the deep ocean, disturbing seabed sediments and resulting in phenomena such as seabed erosion and changes in topography. On the northern slope of the South China Sea and in many coastal margins worldwide, the zones with internal wave action closely overlap with areas where natural gas hydrates are present. However, due to significant differences in the spatial and temporal scales, understanding the influence of internal waves on methane releases from deep seabeds is challenging. In this study, in situ observations of seabed microseismicity and internal waves are conducted at water depths of 655 meters and 1450 meters in the Pearl River Canyon of the South China Sea. The microseismicity caused by internal waves and seabed methane releases is identified, and a method to establish the correlation between internal waves and seabed methane releases through the use of microseismic recordings is proposed, aiming to obtain direct observational evidence of internal waves intensifying seabed methane releases. The results show that internal waves and seabed methane releases generate significant microseismic signals, indicating the continuous influence of internal waves on the deep seabed of the northern slope of the South China Sea and revealing active methane release phenomena on the seabed. At both long and short time scales, internal waves increase the frequency of seabed methane releases by 4.2 times and 2.4 times, respectively, while also enhancing the intensity of these releases. These changes are influenced by the alterations in seabed flow velocity, pressure, and temperature that are induced by internal wave activities. This study emphasizes that microseismic signals are effective carriers of information for multiscale geological processes on seabeds and suggests that internal waves exacerbate marine geological hazards and contribute to global climate change by intensifying seabed methane relea

关键词： Internal waves Seabed methane release Microseismic observation Ocean bottom seismometer Northern slope of the South China Sea

非合作目标交会的双层MPC全局轨迹规划控制

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航空学报 2021年第11期42卷 217-228页

作者：董凯凯罗建军马卫华高登巍谭龙玉西北工业大学航天学院西安710072 中国兵器工业第203研究所西安710065 上海航天控制技术研究所上海201109

针对空间非合作目标近距离视线交会中的全局最优鲁棒轨迹规划与控制问题,提出了基于高斯伪谱方法(GPM)和线性时变模型预测控制(LTVMPC)的双层模型预测控制(MPC)算法。在轨迹规划方面,以视线坐标系下的相对轨道动力学为模型、能量最少和... 详细信息

针对空间非合作目标近距离视线交会中的全局最优鲁棒轨迹规划与控制问题,提出了基于高斯伪谱方法(GPM)和线性时变模型预测控制(LTVMPC)的双层模型预测控制(MPC)算法。在轨迹规划方面,以视线坐标系下的相对轨道动力学为模型、能量最少和控制精度最优为性能指标构建最优控制问题,利用GPM精度高、收敛速度快的特点将最优控制问题转化为易于求解的全局非线性规划问题,在MPC框架下求解得到全局最优的标称轨迹,克服了传统的MPC不适用于全局大范围非线性规划的缺点;在轨迹跟踪控制方面,考虑预测时域内状态转移矩阵的时变特性,设计了LTVMPC算法对标称轨迹进行追踪,避免了存在不确定性时轨迹的重规划,从而降低在线计算量,保证算法在线自主实施,并且采用滚动优化的策略使算法对不确定性具有鲁棒性。由于规划层和控制层考虑的约束相同,因此规划的轨迹是可控、可达的。数字仿真表明,在燃料消耗和交会时间等方面,提出的方法均显著优于传统的MPC方法,相较于传统的MPC方法,新算法的交会时间减少50%左右,燃料消耗降低30%以上。

关键词：空间非合作目标视线(LOS)坐标系双层模型预测控制高斯伪谱法(GPM) 线性时变模型预测控制(LTVMPC)

Sucrose-associated SnRK1a1-mediated phosphorylation of Opaque2 modulates endosperm filling in maize

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Molecular Plant 2024年第5期17卷 788-806页

作者： Tao Yang Yunqin Huang longyu Liao Shanshan Wang Haoyu Zhang Jingying Pan Yongcai Huang Xiaoling Li Di Chen Tao Liu Xiaoduo Lu Yongrui Wu State Key Laboratory of Crop Gene Exploration and Utilization in Southwest China Sichuan Agricultural UniversityChengdu 611130SichuanChina National Key Laboratory of Plant Molecular Genetics CAS Center for Excellence in Molecular Plant SciencesShanghai lnstitute of Plant Physiology and EcologyChinese Academy of SciencesShanghai 200032China Institute of Molecular Breeding for Maize Qilu Normal UniversityJinanChina

During maize endosperm filling,sucrose not only serves as a source of carbon skeletons for storage-reserve synthesis but also acts as a stimulus to promote this ***,the molecular mechanisms underlying sucrose and endosperm filling are poorly *** this study,we found that sucrose promotes the expression of endosperm-filling hub gene Opaque2(O2),coordinating with storage-reserve *** showed that the protein kinase SnRK1a1 can attenuate O2-mediated transactivation,but sucrose can release this *** assays revealed that SnRK1a1 phosphorylates O2 at serine 41(S41),negatively affecting its protein stability and transactivation *** observed that mutation of SnRK1a1 results in larger seeds with increased kernel weight and storage reserves,while overexpression of SnRK1a1 causes the opposite *** of the native O2(O2-OE),phospho-dead(O2-SA),and phospho-mimetic(O2-SD)variants all increased 100-kernel *** O2-SA seeds exhibit smaller kernel size,they have higher accumulation of starch and proteins,resulting in larger vitreous endosperm and increased test weight.O2-SD seeds display larger kernel size but unchanged levels of storage reserves and test weight.O2-OE seeds show elevated kernel dimensions and nutrient storage,like a mixture of O2-SA and O2-SD ***,our study discovers a novel regulatory mechanism of maize endosperm *** of S41 as a SnRK1-mediated phosphorylation site in O2 offers a potential engineering target for enhancing storage-reserve accumulation and yield in maize.

关键词： maize Opaque2 SnRK1 endosperm phosphorylation sucrose

Viscoelastic solution of optimal reserved deformation for deep soft rocktunnels with large deformation

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Geohazard Mechanics 2024年第2期2卷 83-94页

作者： longyu Luo Mingming He Guofeng Li State Key Laboratory of Eco-hydraulics in Northwest Arid Region Xi'an University of Technology710048China

In the construction process of soft rock tunnels,determining a reasonable amount of reserved deformation is important to ensure the tunnel *** article presents the viscoelastic solution of reserved deformation for deep soft rock tunnels considering the support *** on the analytical solution of the Burgers model,the expression of surrounding rock displacement was derived by considering reserved deformation and optimal reserved ***,based on numerical simulation experiments,the variation laws and errors of the numerical and analytical solutions of the expressions of reserved deformation and surrounding rock displacement were *** gain a better understanding of the factors that affect reserved deformation,the factors inﬂuencing the expression of optimal reserved deformation were *** errors in the numerical simulation and analytical solution results were within 10%.This study could provide a theoretical basis for determining the amount of reserved deformation and analyzing the variation law of surrounding rock affected by the amount of reserved deformation.

关键词： Reserved deformation Circular cavity Viscoelastic decomposition Burgers model