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Perturbed low-thrust geostationary orbit transfer guidance via polynomial costate estimation

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Chinese Journal of Aeronautics 2024年第3期37卷 181-193页

作者： zhao li Hengnian li Fanghua JIANG Junfeng li State Key Laboratory of Astronautic Dynamics Xi’an Satellite Control CenterXi’an 710043China School of Aerospace Engineering Tsinghua UniversityBeijing 100084China

This paper proposes an optimal,robust,and efficient guidance scheme for the perturbed minimum-time low-thrust transfer toward the geostationary *** Earth’s oblateness perturbation and shadow are taken into *** is difficult for a Lyapunov-based or trajectory-tracking guidance method to possess multiple characteristics at the same time,including high guidance optimality,robustness,and onboard computational *** this work,a concise relationship between the minimum-time transfer problem with orbital averaging and its optimal solution is identified,which reveals that the five averaged initial costates that dominate the optimal thrust direction can be approximately determined by only four initial modified equinoctial orbit elements after a coordinate *** on this relationship,the optimal averaged trajectories constituting the training dataset are randomly generated around a nominal averaged *** polynomial regression models are trained on the training dataset and are regarded as the costate *** the transfer,the spacecraft can obtain the real-time approximate optimal thrust direction by combining the costate estimations provided by the estimators with the current state at any ***,all these computations onboard are *** simulation results show that the proposed guidance scheme possesses extremely high guidance optimality,robustness,and onboard computational efficiency.

关键词： Low thrust Orbital transfer Trajectory optimization Guidance Indirect method Orbital averaging Machine learning Geostationary satellites

Accurately tracking hypersonic gliding vehicles via an LEO mega-constellation in relay tracking mode

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Journal of Systems Engineering and Electronics 2024年第1期35卷 211-221页

作者： li zhao WANG Yidi ZHENG Wei College of Aerospace Science and Engineering National University of Defense TechnologyChangsha 410073China

In order to effectively defend against the threats of the hypersonic gliding vehicles(HGVs),HGVs should be tracked as early as possible,which is beyond the capability of the ground-based *** benefited by the developing megaconstellations in low-Earth orbit,this paper proposes a relay tracking mode to track HGVs to overcome the above *** whole tracking mission is composed of several tracking intervals with the same *** each tracking interval,several appropriate satellites are dispatched to track the *** that are planned to take part in the tracking mission are selected by a new derived observability *** tracking performances of the proposed tracking mode and the other two traditional tracking modes,including the stare and track-rate modes,are compared by *** results show that the relay tracking mode can track the whole trajectory of a HGV,while the stare mode can only provide a very short tracking ***,the relay tracking mode achieve higher tracking accuracy with fewer attitude controls than the track-rate mode.

关键词： target tracking mega-constellation hypersonic gliding vehicle(HGV) sensor selection observability analysis

Interference-induced suppression of particle emission from a Bose-Einstein condensate in lattice with time-periodic modulations

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Chinese Physics B 2024年第10期33卷 153-158页

作者： Long-Quan Lai zhao li School of Science Nanjing University of Posts and TelecommunicationsNanjing 210023China School of Electronic Engineering Chengdu Technological UniversityChengdu 611730China

Emission of matter-wave jets from a parametrically driven condensate has attracted significant experimental and theoretical attention due to the appealing visual effects and potential metrological *** this work,we investigate the collective particle emission from a Bose-Einstein condensate confined in a one-dimensional lattice with periodically modulated interparticle *** give the regimes for discrete modes,and find that the emission can be distinctly *** configuration induces a broad band,but few particles are ejected due to the interference of the matter *** further qualitatively model the emission process and demonstrate the short-time *** engineering provides a way to manipulate the propagation of particles and the corresponding dynamics of condensates in lattices,and may find application in the dynamical excitation control of other nonequilibrium problems with time-periodic driving.

关键词： Bose-Einstein condensate matter-wave jet periodic modulation

Differences and similarities in radial growth of Betula species to climate change

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Journal of Forestry Research 2024年第2期35卷 176-187页

作者： Di liu Yang An zhao li Zhihui Wang Yinghui zhao Xiaochun Wang Center for Ecological Research Key Laboratory of Sustainable Forest Ecosystem ManagementMinistry of EducationCollege of ForestryNortheast Forestry UniversityHarbin 150040People’s Republic of China Changan Park in Shijiazhuang Shijiazhuang 050000People’s Republic of China Shijiazhuang Landscape Greening Engineering Project Construction Center Shijiazhuang 050000People’s Republic of China Heilongjiang Institute of Meteorological Science Harbin 150030People’s Republic of China School of life Qufu Normal UniversityQufu 273100People’s Republic of China

Betula platyphylla and Betula costata are important species in mixed broadleaved-Korean pine(Pinus koraiensis)***,the specific ways in which their growth is affected by warm temperatures and drought remain *** address this issue,60 and 62 tree-ring cores of *** and *** were collected in Yichun,*** dendrochronological methods,the response and adaptation of these species to climate change were examined.A“hysteresis effect”was found in the rings of both species,linked to May–September moisture conditions of the previous *** growth of *** was positively correlated with the standardized precipitation-evapotranspiration index(SPEI),the precipitation from September to October of the previous year,and the relative humidity in October of the previous *** of *** is primarily restricted by moisture conditions from September to *** contrast,*** growth is mainly limited by minimum temperatures in May–June of both the previous and current *** droughts,*** had a faster recovery rate compared to *** the context of rising temperatures since 1980,the correlation between *** growth and monthly SPEI became positive and strengthened over time,while the growth of *** showed no conspicuous *** findings suggest that the growth of *** is already affected by warming temperatures,whereas *** may become limited if warming continues or *** change could disrupt the succession of these species,possibly accelerating the succession of pioneer *** results of this research are of great significance for understanding how the growth changes of birch species under warming and drying conditions,and contribute to understanding the structural adaptation of mixed broadleaved-Korean pine(Pinus koraiensis)forests under climate change.

关键词： Tree rings Betula platyphylla Betula costata Climate response Moving correlation Extreme drought

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Petroleum Science 2024年第4期21卷 2383-2392页

作者： li-Ming zhao Cai-Ping Lu Yang liu Chao-Chao li School of Mines China University of Mining and Technology Henan Institute of Geophysical Space Information

The similarities and differences in inherent mechanism and characteristic frequency between the onedimensional(1D) poroelastic model and the layered White model were investigated. This investigation was conducted under the assumption that the rock was homogenous and isotropic at the mesoscopic scale. For the inherent mechanism, both models resulted from quasi-static flow in a slow P-wave diffusion mode, and the differences between them originated from saturated fluids and boundary conditions. On the other hand, for the characteristic frequencies of the models, the characteristic frequency of the 1D poroelastic model was first modified because the elastic constant and formula for calculating it were misused and then compared to that of the layered White model. Both of them moved towards higher frequencies with increasing permeability and decreasing viscosity and diffusion length. The differences between them were due to the diffusion length. The diffusion length for the 1D poroelastic model was determined by the sample length, whereas that for the layered White model was determined by the length of the representative elementary volume(REV). Subsequently, a numerical example was presented to demonstrate the similarities and differences between the models. Finally, published experimental data were interpreted using the 1D poroelastic model combined with the Cole-Cole *** prediction of the combined model was in good agreement with the experimental data, thereby validating the effectiveness of the 1D poroelastic model. Furthermore, the modified characteristic frequency in our study was much closer to the experimental data than the previous prediction, validating the effectiveness of our modification of the characteristic frequency of the 1D poroelastic model. The investigation provided insight into the internal relationship between wave-induced fluid flow(WIFF)models at macroscopic and mesoscopic scales and can aid in a better understanding of the elastic modulus d

关键词： 1D poroelastic model Layered White model Quasi-static flow Slow P-wave diffusion Characteristic frequency Diffusion length

Joint alignment and steering to manage interference

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Digital Communications and Networks 2024年第2期10卷 429-438页

作者： zhao li Xiujuan liang Yinghou liu Jia liu Zheng Yan School of Cyber Engineering Xidian UniversityXi'an710126China Technol.on Commun.Net.Lab. The 54th Research Inst.of China Elec.Technol.Group Corp.Shijiazhuang050081China School of Computer Science and Technology Xidian UniversityXi'an710126China The Department of Communications and Networking(Comnet) Aalto University02150EspooFinland

In wireless communication networks,mobile users in overlapping areas may experience severe interference,therefore,designing effective Interference Management(IM)methods is crucial to improving network ***,when managing multiple disturbances from the same source,it may not be feasible to use existing IM methods such as Interference Alignment(IA)and Interference Steering(IS)*** is because with IA,the aligned interference becomes indistinguishable at its desired Receiver(Rx)under the cost constraint of Degrees-of-Freedom(DoF),while with IS,more transmit power will be consumed in the direct and repeated application of IS to each *** remedy these deficiencies,Interference Alignment Steering(IAS)is proposed by incorporating IA and IS and exploiting their advantages in *** IAS,the interfering Transmitter(Tx)first aligns one interference incurred by the transmission of one data stream to a one-dimensional subspace orthogonal to the desired transmission at the interfered Rx,and then the remaining interferences are treated as a whole and steered to the same subspace as the aligned ***,two improved versions of IAS,i.e.,IAS with Full Adjustment at the Interfering Tx(IAS-FAIT)and Interference Steering and Alignment(ISA),are *** former considers the influence of IA on the interfering user-pair's *** orthogonality between the desired signals at the interfered Rx can be maintained by adjusting the spatial characteristics of all interferences and the aligned interference components,thus ensuring the Spectral Efficiency(SE)of the interfering communication *** ISA,the power cost for IS at the interfered Tx is minimized,hence improving SE performance of the interfered *** the proposed methods are realized at the interfering and interfered Txs cooperatively,the expenses of IM are shared by both *** in-depth simulation results show that joint use of IA and

关键词： Interference Interference management Interference alignment Interference steering Spectral efficiency

Impact of Mo/Ni alloying on microstructural modulation and low-temperature toughness of high-strength low-alloy steel

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Journal of Iron and Steel Research International 2024年第7期31卷 1746-1762页

作者： Wei liu Hong-li zhao Bing-xing Wang Yong Tian State Key Laboratory of Rolling and Automation Northeastern UniversityShenyang 110819LiaoningChina

The high-strength low-alloy steel plates with varying Ni/Mo contents were manufactured using the thermos-mechanical control *** investigation was conducted to explore the effect of Ni/Mo microalloying on microstructure evolution and mechanical properties of the *** results revealed that the increase in Ni content from 1 to 2 wt.%reduced the transition temperature of ferrite and the growth range of ferritic grain was narrowed,which promoted grain *** optimized combination of grain size,high-angle grain boundaries(HAGBs),and martensite-austenite(M-A)islands parameter contributed to the excellent impact toughness of S1 steel at-100℃(impact absorbed energy of 218.2 J at-100℃).As the Mo increases from 0 to 2 wt.%,the matrix structure changes from multiphase structure to granular bainite,which increases the average effective grain size to~4.62 pm and reduces HAGBs proportion to~36.22%.With these changes,the low-temperature impact toughness of S3 steel is *** addition,based on the analysis of the characteristics of crack propagation path,it was found that M-A islands with low content(~2.21%)and small size(~1.76 pm)significantly retarded crack propagation,and the fracture model of M-A islands with different morphologies was further ***,correlation between behaviour of delamination and toughness was further analysed by observing delamination size and impact energy parameters.

关键词： High-strength low-alloy steel Microstructural regulation Ni addition Mo addition Crack propagation Low-temperature toughness

Visible light Indoor Positioning System Based on Pisarenko Harmonic Decomposition and Neural Network

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Chinese Journal of Electronics 2024年第1期33卷 195-203页

作者： li zhao Yi REN Qi WANG Lange DENG Feng ZHANG School of Electronic Information Engineering Xi’an Technological University

Visible-light indoor positioning is a new generation of positioning technology that can be integrated into smart lighting and optical communications. The current received signal strength(RSS)-based visible-light positioning systems struggle to overcome the interferences of background and indoor-reflected noise. Meanwhile, when ensuring the lighting, it is impossible to use the superposition of each light source to accurately distinguish light source information; furthermore, it is difficult to achieve accurate positioning in complex indoor environments. This study proposes an indoor positioning method based on a combination of power spectral density detection and a neural network. The system integrates the mechanism for visible-light radiation detection with RSS theory, to build a back propagation neural network model fitting for multiple reflection channels. Different frequency signals are loaded to different light sources at the beacon end, and the characteristic frequency and power vectors are obtained at the location end using the Pisarenko harmonic decomposition method. Then, a complete fingerprint database is established to train the neural network model and conduct location tests. Finally, the location effectiveness of the proposed algorithm is verified via actual positioning experiments. The simulation results show that, when four groups of sinusoidal waves with different frequencies are superimposed with white noise, the maximum frequency error is 0.104 Hz and the maximum power error is 0.0362 W. For the measured positioning stage, a 0.8 m × 0.8 m × 0.8 m solid wood stereoscopic positioning model is constructed, and the average error is 4.28 cm. This study provides an effective method for separating multi-source signal energies, overcoming background noise, and improving indoor visible-light positioning accuracies.

关键词： Neural networks Measurement uncertainty Position measurement Harmonic analysis light emitting diodes Frequency estimation Indoor positioning systems

Research on Data Theory of Value

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China Economist 2024年第3期19卷 21-38页

作者： li Haijian zhao li Institute of Quantitative&Technological Economics China Academy of Social Sciences(CASS)BeijingChina Ningbo University NingboChina

This paper explores the data theory of value along the line of reasoning epochal characteristics of data-theoretical innovation-paradigmatic transformation and,through a comparison of hard and soft factors and observation of data peculiar features,it draws the conclusion that data have the epochal characteristics of non-competitiveness and non-exclusivity,decreasing marginal cost and increasing marginal return,non-physical and intangible form,and non-finiteness and *** is the epochal characteristics of data that undermine the traditional theory of value and innovate the“production-exchange”theory,including data value generation,data value realization,data value rights determination and data value *** the perspective of data value generation,the levels of data quality,processing,use and connectivity,data application scenarios and data openness will influence data *** the perspective of data value realization,data,as independent factors of production,show value creation effect,create a value multiplier effect by empowering other factors of production,and substitute other factors of production to create a zero-price *** the perspective of data value rights determination,based on the theory of property,the tragedy of the private outweighs the comedy of the private with respect to data,and based on the theory of sharing economy,the comedy of the commons outweighs the tragedy of the commons with respect to *** the perspective of data pricing,standardized data products can be priced according to the physical product attributes,and non-standardized data products can be priced according to the virtual product *** on the epochal characteristics of data and theoretical innovation,the“production-exchange”paradigm has undergone a transformation from“using tangible factors to produce tangible products and exchanging tangible products for tangible products”to“using intangible factors to produce tangible products and exchanging

关键词： Data theory of value data value generation data value rights determination data value pricing