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Spatiotemporal variations of parameters of internal solitary waves in the northern South China Sea

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Journal of Oceanology and Limnology 2024年第2期42卷 421-438页

作者： Yu’ang liu Yifei JIang Xiaojiang ZHang Zhiyuan Wang Yu CAO Huizan Wang College of Meteorology and Oceanography National University of Defense TechnologyChangsha 410000China

The dynamic parameters for internal solitary waves(ISWs)derived from the extended Korteweg-de Vries(eKdV)equation play an important role in the understanding and prediction of ISWs.The spatiotemporal variations of the dynamic parameters of the ISWs in the northern South China Sea(SCS)were studied based on the reanalysis of long-term temperature and salinity datasets.The results for spectrum analysis show that there are definite geographical differences for the periodic variation of the parameters:in shallow water,all parameters vary with a wave period of one year,while in deep water wave components of the parameters at other frequencies exist.Using wavelet analysis,the wavelet power spectral densities in deep water exhibited an inter-annual variation pattern.For example,the wave component of the dispersion coefficient with a wave period of about half a year reached its power peak once every two years.Based on previous work,this inter-annual variation pattern was deduced to be caused by dynamic processes.In further work on the regulatory mechanisms,empirical orthogonal function(EOF)decomposition was performed.It was found that the modes of the dispersion coefficient have different geographical distributions,explaining the reason why the wave components in different frequencies appeared in different locations.The numerical simulation results confirm that the variations in the parameters of the ISWs derived from the eKdV equation could affect the waveforms significantly because of changes in the polarity of the ISWs.Therefore,the periodic variations of the dynamic parameters are related to the geographical location because of dynamic processes operating.

关键词： internal solitary waves(ISWs) dynamic parameters eKdV equation spatiotemporal variation polarity empirical orthogonal function(EOF)decomposition

A Scenario-classification Hybrid-based Banding Method for Power Transfer Limits of Critical Inter-corridors

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Journal of Modern Power Systems and Clean Energy 2024年第2期12卷 547-560页

作者： Lidong Yi Maosheng Ding Jili Wang Gao Qiu Fei Xue Ji'ang liu Yuxiong Huang Gengfeng Li Junyong liu State Grid Ningxia Electric Power Co. Ltd.YinchuanChinaand M.Ding is also with State Grid Ningxia Electric Power Research InstituteYinchuanChina Northwest Branch State Grid Corporation of ChinaXi’anChina School of Electrical Engineering Sichuan UniversityChengduChina State Grid Ningxia Electric Power Research Institute Yinchuan YinchuanChina School of Electrical Engineering Xi’an Jiaotong UniversityXi’anChina IEEE

To secure power system operations,practical dispatches in industries place a steady power transfer limit on critical inter-corridors,rather than high-dimensional and strong nonlinear stability constraints.However,computational complexities lead to over-conservative pre-settings of transfer limit,which further induce undesirable and non-technical congestion of power transfer.To conquer this barrier,a scenario-classification hybrid-based banding method is proposed.A cluster technique is adopted to separate similarities from historical and generated operating condition dataset.With a practical rule,transfer limits are approximated for each operating cluster.Then,toward an interpretable online transfer limit decision,costsensitive learning is applied to identify cluster affiliation to assign a transfer limit for a given operation.In this stage,critical variables that affect the transfer limit are also picked out via mean impact value.This enables us to construct low-complexity and dispatcher-friendly rules for fast determination of transfer limit.The numerical case studies on the IEEE 39-bus system and a real-world regional power system in China illustrate the effectiveness and conservativeness of the proposed method.

关键词： Transfer limit transfer capability power transfer inter-corridor cluster cost-sensitive learning banding power system operation

Real-time GNSS precise point positioning with smartphones for vehicle navigation

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Satellite Navigation 2022年第3期3卷 140-161,I0004页

作者： Zishen Li Liang Wang Ningbo Wang Ran Li ang liu Aerospace Information Research Institute(AIR) Chinese Academy of Sciences(CAS)Beijing100094China School of Electronic Electrical and Communicating EngineeringUniversity of Chinese Academy of Sciences19A Yuquan RoadShijingshan DistrictBeijing100049China

The availability of raw Global Navigation Satellite System(GNSS)measurements from Android smart devices gives new possibilities for precise positioning solutions,e.g.,Precise Point Positioning(PPP).However,the accuracy of the PPP with smart devices currently is a few meters due to the poor quality of the raw GNSS measurements in a kinematic scenario and in urban environments,particularly when the smart devices are placed inside vehicles.To promote the application of GNSS PPP for land vehicle navigation with smart devices,this contribution studies the real-time PPP with smartphones.For data quality analysis and positioning performance validation,two vehicle-based kinematic positioning tests were carried out using two Huawei Mate30 smartphones and two Huawei P40 smartphones with different installation modes:the vehicle-roof mode with smartphones mounted on the top roof outside the vehicle,and the dashboard mode with smartphones stabilized on the dashboard inside the vehicle.To realize high accuracy positioning,we proposed a real-time smartphone PPP method with the data processing strategies adapted for smart devices.Positioning results show that the real-time PPP can achieve the horizontal positioning accuracy of about 1–1.5 m in terms of root-mean-square and better than 2.5 m at the 95th percentile for the vehicle-based kinematic positioning with the experimental smartphones mounted on the dashboard inside the vehicle,which is the real scenario in vehicle navigation.

关键词： Global Navigation Satellite System Smartphone positioning Precise point positioning Raw GNSS measurements Land vehicle navigation

Progress of Geodesy Related Ionosphere from Chinese Scientists in the Period of 2019—2023

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测绘学报:英文版 2023年第3期6卷 115-123页

作者： Zishen LI Ningbo Wang ang liu ang LI Heng Yang Dongshen ZHAO Xiaodong REN Andong HU Aerospace Information Research Institute Chinese Academy of ScienceBeijing 100094China Qilu Aerospace Information Research Institute Jinan 250101China School of Electronic Information and Engineering Yangtze Normal UniversityChongqing 408100China School of Environmental Science and Spatial Informatics China University of Mining and TechnologyXuzhou 221116China School of Geodesy and Geomatics Wuhan UniversityWuhan 430072China

The ionosphere is the ionized part of the upper atmosphere of the Earth,which plays an important role in atmospheric electricity and forms the inner edge of the magnetosphere.It influences radio propagation significantly,such as the Global Navigation Satellite System(GNSS).Meanwhile,the GNSS is also an essential technique for sensing the variation of ionosphere.During the years of 2019—2023,a large number of Chinese geodesy scientists devoted much efforts to the geodesy related ionosphere.Due to the very limited length,the achievements are carried out from the following six aspects,including:①The ionospheric correction models for BDS and BDSBAS;②Real-time global ionospheric monitoring and modeling;③The ionospheric 2D and 3D modeling based on GNSS and LEO satellites;④The ionospheric prediction based on artificial intelligence;⑤The monitoring and mitigation of ionospheric disturbances for GNSS users;⑥The ionospheric related data products and classical applications.

关键词： ionosphere Global Navigation Satellite System(GNSS) BDS satellite-based augmentation system

Quantum-Enhanced Blockchain: A Secure and Practical Blockchain Scheme

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Computers, Materials & Continua 2023年第7期76卷 259-277页

作者： ang liu Xiu-Bo Chen Gang Xu Zhuo Wang Xuefen Feng Huamin Feng Information Security Center State Key Laboratory of Networking and Switching TechnologyBeijing University of Posts and TelecommunicationsBeijing100876China Network and Information Management Division Beijing Electronic Science and Technology InstituteBeijing100070China School of Information Science and Technology North China University of TechnologyBeijing100144China School of Artificial Intelligence Beijing University of Posts TelecommunicationsBeijing100876China Mathematics Teaching and Research Center Beijing Fengtai Yihai High SchoolBeijing100070China General Office Beijing Electronic Science and Technology InstituteBeijing100070China

The rapid advancement of quantum technology poses significant security risks to blockchain systems.However,quantum technology can also provide solutions for enhancing blockchain security.In this paper,we propose a quantum-enhanced blockchain scheme to achieve a high level of security against quantum computing attacks.We first discuss quantum computing attacks on classic blockchains,including attacks on hash functions,digital signatures,and consensus mechanisms.We then introduce quantum technologies,such as a quantum hash function(QHF),a quantum digital signature(QDS),and proof of authority(PoA)consensus mechanism,into our scheme to improve the security of the blockchain system.Our security analysis demonstrates that our scheme offers superior security against quantum and classic attacks.Finally,we compare our scheme with previous works,showing that our scheme has achieved a perfect balance in terms of practicality,reliability,scalability,and efficiency.Overall,this work contributes to the ongoing research on quantum blockchain in the quantum era.

关键词： Quantum blockchain quantum hash function quantum digital signature

Water sorption on coal:effects of oxygen-containing function groups and pore structure

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International Journal of Coal Science & Technology 2021年第5期8卷 983-1002页

作者： ang liu Shimin liu Peng liu Kai Wang Department of Energy and Mineral Engineering G3 Center and Energy InstituteThe Pennsylvania State UniversityUniversity ParkPA 16802USA State Key Laboratory of Coal Mine Disaster Dynamics and Control Chongqing UniversityChongqing 400030China School of Emergency Management and Safety Engineering China University of Mining and Technology(Beijing)Beijing 100083China

Coal-water interactions have profound influences on gas extraction from coal and coal utilization.Experimental measurements on three coals using X-ray photoelectron spectroscopy(XPS),low-temperature nitrogen adsorption and dynamic water vapor sorption(DVS)were conducted.A mechanism-based isotherm model was proposed to estimate the water vapor uptake at various relative humidities,which is well validated with the DVS data.The validated isotherm model of sorption was further used to derive the isosteric heat of water vapor sorption.The specific surface area of coal pores is not the determining parameter that controls water vapor sorption at least during the primary adsorption stage.Oxidation degree dominates the primary adsorption,and which togethering with the cumulative pore volume determine the secondary adsorption.Higher temperature has limited effects on primary adsorption process.The isosteric heat of water adsorption decreases as water vapor uptake increases,which is found to be close to the latent heat of bulk water condensation at higher relative humidity.The results confirmed that the primary adsorption is controlled by the stronger bonding energy while the interaction energy between water molecules during secondary adsorption stage is relatively weak.However,the thermodynamics of coal-water interactions are complicated since the internal bonding interactions within the coal are disrupted at the same time as new bonding interactions take place within water molecules.Coal has a shrinkage/swelling colloidal structure with moisture loss/gain and it may exhibit collapse behavior with some collapses irreversible as a function of relative humidity,which further plays a significant role in determining moisture retention.

关键词： Water vapor Isotherm Surface oxidation Pore collapse Isosteric heat of adsorption

Characteristics and close-range exploration methods of near- Earth asteroid 2016HO_(3)

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Astronomical Techniques and Instruments 2024年第1期1卷 42-51页

作者： He Zhang Fei Li Linzhi Meng Fuming Zeng Xiaoyu Jia Yu’ang liu Beijing Institute of Spacecraft System Engineering Beijing 100094China

The characteristics of asteroids are vital parameters for planning asteroid exploration missions.These characteristics have been explored in close range for some typical asteroids,and are summarized in the article.This allows estimates of the characteristics of asteroid 2016HO_(3),the target of the first Chinese asteroid exploration mission,Tianwen 2.We obtain 80 characteristic parameters in 9 categories and analyze their impacts on the mission.By comparing three close-range exploration modes,we provide advantages and disadvantages of each,and propose suitable methods for the exploration of 2016HO_(3).Owing to the weak gravity and small size of 2016HO_(3),a combination of multiple hovering positions and active orbiting is recommended for scientific exploration.

关键词： Near-Earth asteroid 2016HO_(3) Tianwen 2 Close-range exploration Characteristics

基于滑窗初始点dSTEC定权的全球实时电离层综合

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测绘学报 2024年第2期53卷 296-305页

作者：王宁波李子申李昂张研刘昂汪亮中国科学院空天信息创新研究院北京100094 中国科学院大学电子电气与通信工程学院北京100049 齐鲁空天信息研究院山东济南250101

自2017年起,国际GNSS服务组织(IGS)部分电离层分析中心先后提供全球实时电离层校正服务。针对实际应用中单一分析中心实时电离层产品存在的可靠性差问题,本文提出了基于滑窗初始点差分斜向总电子含量(dSTEC)定权的全球实时电离层综合方... 详细信息

自2017年起,国际GNSS服务组织(IGS)部分电离层分析中心先后提供全球实时电离层校正服务。针对实际应用中单一分析中心实时电离层产品存在的可靠性差问题,本文提出了基于滑窗初始点差分斜向总电子含量(dSTEC)定权的全球实时电离层综合方法。以中国科学院(CAS)、法国空间研究中心(CNES)、西班牙加泰罗尼亚理工大学(UPC)及武汉大学(WHU)实时产品为基础,实现了实时全球电离层地图(RT-GIM)产品的例行综合。从电离层延迟误差修正、单频标准单点定位(SF-SPP)及单频精密单点定位(SF-PPP) 3个方面,分析2022年2月15日至2022年3月15日综合RT-GIM产品的应用性能。以IGS事后GIM为参考,本文综合RT-GIM与UPC综合RT-GIM对应的RMS为分别为3.30和3.20 TECU,二者精度相当;以定位残差95%分位数为统计量,与IGS事后GIM产品相比,综合RT-GIM对应的SF-SPP及SF-PPP精度分别低7.7%和4.9%;与北斗三号广播电离层模型BDGIM相比,综合RT-GIM对应的SF-SPP及SF-PPP精度分别提升了15.9%和9.5%。自2022年起,CAS综合RT-GIM产品已例行提交至IGS。

关键词：实时全球电离层地图差分斜向总电子含量滑动窗口实时综合实时服务

Mechanical criterion for coal and gas outburst:a perspective from multiphysics coupling

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International Journal of Coal Science & Technology 2021年第6期8卷 1423-1435页

作者： Ting liu Baiquan Lin Xuehai Fu ang liu School of Safety Engineering China University of Mining&TechnologyXuzhou 221116China Key Laboratory of CBM Resources and Dynamic Accumulation Process China University of Mining&TechnologyXuzhou 221008China Department of Energy and Mineral Engineering G3 Center and EMS Energy InstituteThe Pennsylvania State UniversityUniversity ParkPAUSA

Although a series of hypotheses have been proposed,the mechanism underlying coal and gas outburst remains unclear.Given the low-index outbursts encountered in mining practice,we attempt to explore this mechanism using a multiphysics coupling model considering the effects of coal strength and gas mass transfer on failure.Based on force analysis of coal ahead of the heading face,a risk identification index C_(m)and a critical criterion(C_(m)≥1)of coal instability are proposed.According to this criterion,the driving force of an outburst consists of stress and gas pressure gradients along the heading direction of the roadway,whereas resistance depends on the shear and tensile strengths of the coal.The results show that outburst risk decreases slightly,followed by a rapid increase,with increasing vertical stress,whereas it decreases with increasing coal strength and increases with gas pressure monotonically.Using the response surface method,a coupled multi-factor model for the risk identification index is developed.The results indicate strong interactions among the controlling factors.Moreover,the critical values of the factors corresponding to outburst change depending on the environment of the coal seams,rather than being constants.As the buried depth of a coal seam increases,the critical values of gas pressure and coal strength decrease slightly,followed by a rapid increase.According to its controlling factors,outburst can be divided into stress-dominated,coal-strength-dominated,gas-pressure-dominated,and multi-factor compound types.Based on this classification,a classified control method is proposed to enable more targeted outburst prevention.

关键词： Coal and gas outburst Critical criterion Multiphysics coupling Response surface method