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Collision risk assessment for constellation satellites based on a space debris environment topological network model 认领 引用 被引量：1
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作者 Yurun YUAN Jingrui ZHANG +2 位作者 Keying YANG Lincheng LI Hao WU 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2026年第2期472-484,共13页
In recent years,the rapid development of mega-constellations has significantly exacerbated the deterioration of the space debris environment,posing substantial and escalating threats to the safety of spacecraft.This s... In recent years,the rapid development of mega-constellations has significantly exacerbated the deterioration of the space debris environment,posing substantial and escalating threats to the safety of spacecraft.This study aims to explore the complex evolution of the space debris environment and assess the collision risks associated with spacecraft.First,a space debris environment topological network model is proposed,which incorporates interdisciplinary methods from topological networks,fluid mechanics,and spacecraft dynamics.This model enables a structured representation of the relationships among space objects and provides rapid predictions of the space debris environment.Then,a collision probability algorithm based on the topological network model is introduced.This algorithm inherits the efficiency advantages of the topological network model and has been validated for reliability through comparison with the classical ESA’s DRAMA software.Finally,based on the above models,the collision risks of constellation satellites in Low Earth Orbit(LEO)are analyzed,including both operational and deorbit processes.The study reveals that constellation satellites face a much higher risk of internal collisions with satellites from the same constellation during operations than that with other space objects.Additionally,during the satellite deorbit process,the collision risk peaks when satellites traverse the operational region of Starlink satellites. 展开更多
关键词 Collision probability Computing resource Constellation Space debris Topological network model
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Adaptive-length data-driven predictive control for post-operation of space robot non-cooperative target capture with disturbances 认领 引用 被引量：1
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作者 Peiji WANG Bicheng CAI +2 位作者 Chengfei YUE Yong ZHAO Weiren WU 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2026年第2期485-498,共14页
This paper solves the problem of model-free dual-arm space robot maneuvering after non-cooperative target capture under high control quality requirements.The explicit system model is unavailable,and the maneuvering mi... This paper solves the problem of model-free dual-arm space robot maneuvering after non-cooperative target capture under high control quality requirements.The explicit system model is unavailable,and the maneuvering mission is disturbed by the measurement noise and the target adversarial behavior.To address these problems,a model-free Combined Adaptive-length Datadriven Predictive Controller(CADPC)is proposed.It consists of a separated subsystem identification method and a combined predictive control strategy.The subsystem identification method is composed of an adaptive data length,thereby reducing sensitivity to undetermined measurement noises and disturbances.Based on the subsystem identification,the combined predictive controller is established,reducing calculating resource.The stability of the CADPC is rigorously proven using the Input-to-State Stable(ISS)theorem and the small-gain theorem.Simulations demonstrate that CADPC effectively handles the model-free space robot post operation in the presence of significant disturbances,state measurement noise,and control input errors.It achieves improved steady-state accuracy,reduced steady-state control consumption,and minimized control input chattering. 展开更多
关键词 Combined control Data-driven predictive control Post operation Predictive control systems Space non-cooperative target capture
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Additive manufacturing for space applications:A review of materials,methods,and future frontiers 认领 引用 被引量：1
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作者 Dhanesh G.Mohan Saiyathibrahim A +3 位作者 Gopi S Vijaykumar S.Jatti Kumar S Murali Krishnan R 《China Welding》 CAS 2026年第1期1-16,共16页
Additive manufacturing(AM),globally referred to as 3D printing,is a highly flexible manufacturing method that enables the design and creation of complex geometries with ease.This review article comprehensively examine... Additive manufacturing(AM),globally referred to as 3D printing,is a highly flexible manufacturing method that enables the design and creation of complex geometries with ease.This review article comprehensively examines the materials,methods,and applications of AM specifically for the space sector,while identifying current research gaps and proposing future directions.The primary advantages of AM over conventional subtractive manufacturing for space implementations include economic efficiency,unparalleled design freedom,high customizability,tailor-made production,and the ability to process a wide range of materials including metals,polymers,composites,and ceramics.The article focuses on space-grade materials such as high-performance alloys,polymers,and ceramics used in applications ranging from electronic equipment to propulsion systems.It provides a detailed analysis of prevalent metal AM techniques like powder bed fusion and directed energy deposition,as well as non-metal methods including used deposition modeling and selective laser sintering.Through specific case studies,it demonstrates how AM enables part consolidation,weight reduction,and the production of multifunctional components with integrated capabilities.This review will help readers comprehend current trends in space additive manufacturing and understand its future potential in next-generation space applications,from in-situ manufacturing to the realization of fully additively manufactured spacecraft. 展开更多
关键词 Additive manufacturing Space applications Aerospace components In-situ manufacturing Materials processing Design optimization
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Experimental techniques for qualitative and quantitative characterization of shale oil reservoir space,minerals,and fluids 认领 引用 被引量：1
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作者 Siyu Chen Zhenkai Huang +6 位作者 Guangyou Zhu Xi Li Zhiyong Chen Ruilin Wang Yue Huang Shengnan Liu Bijun Huang 《Energy Geoscience》 EI CAS CSCD 2026年第2期1-16,共16页
Characterizing shale oil reservoirs encompassing pore space,mineralogy,and fluids is fundamental to effective exploration and development.Recent advances in experimental techniques have significantly improved both the... Characterizing shale oil reservoirs encompassing pore space,mineralogy,and fluids is fundamental to effective exploration and development.Recent advances in experimental techniques have significantly improved both the qualitative and quantitative analysis of these components;however,a comprehensive systematic review is lacking.High-resolution imaging technologies,such as Scanning Electron Microscopy(SEM),Field Emission Scanning Electron Microscopy(FE-SEM),and Focused Ion Beam Scanning Electron Microscopy(FIB-SEM),enable detailed visualization of pore structures.Gas adsorption and high-pressure mercury intrusion methods provide accurate pore-scale quantification.Moreover,techniques like X-ray Diffraction(XRD),X-ray Fluorescence Spectroscopy(XRF),and Electron Probe Microanalysis(EPMA)allow precise mineral identification and compositional analysis.Confocal Scanning Laser Microscopy(CSLM),Raman Spectroscopy,Nuclear Magnetic Resonance(NMR),and Rock Pyrolysis provide insights into fluid occurrence and content within shale reservoirs.Based on a comprehensive review of existing research,this study identifies several key future directions:(1)addressing the challenges of nanopore observation in reservoir space characterization while minimizing the impact of sample preparation on pore structure;(2)improving the accuracy of quantitative mineral analysis and developing advanced new technologies for the precise measurement of complex mineral compositions;(3)enhancing the fluid quantitative evaluation of fluids by more effectively restoring subsurface geological conditions.This paper presents a current synthesis and forward-looking perspective on experimental techniques supporting shale oil exploration,aiming to guide future research and technological innovation in this field. 展开更多
关键词 Experimental technique Shale oil Reservoir space Mineral analysis Fluid characterization Qualitative and quantitative analysis
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A self-learning refined model and tracking for near space hypersonic vehicle by space-based radar 认领 引用 被引量：1
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作者 Yue XU Quan PAN +2 位作者 Zengfu WANG Hua LAN Shuling JIN 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2026年第5期504-529,共26页
The Near Space Hypersonic Vehicle(NSHV)features a unique design and propulsion system,achieving exceptional speed,range,and maneuverability,which challenge ground-based radars.Space-Based Radar(SBR)offers a breakthrou... The Near Space Hypersonic Vehicle(NSHV)features a unique design and propulsion system,achieving exceptional speed,range,and maneuverability,which challenge ground-based radars.Space-Based Radar(SBR)offers a breakthrough for tracking NSHV targets,with allweather operation and freedom from Earth's curvature,but faces complex coordinate transformations.Traditional models often overlook the NSHV's dynamic gliding trajectory,especially the impact of hidden control variables on maneuvering,causing mismatches during rapid motion changes.This paper proposes a refined tracking model unified in the ECEF coordinate frame,incorporating model parameters that implicitly encode control laws,and presents an ExpectationMaximization Multi-swarm Cooperative Particle Swarm Optimization(EM-MCPSO)framework for both NSHV tracking and model parameter estimation to address this problem.To minimize conversion errors,a transformation matrix directly represented by the state in the EarthCentered Earth-Fixed(ECEF)coordinate is derived.Then the hybrid aerodynamic acceleration coefficients are introduced to precisely describe the dynamic behaviors,formulating target tracking as a joint estimation problem of state and parameters within EM framework.Finally,a self-learning algorithm based on a master–slave structured PSO is proposed to solve the optimization of the conditional expectations of EM under strong nonlinearity,with a Proportional-Derivative(PD)controller accelerating convergence,and updating the population structure with historical data.Simulations of vertical gliding and horizontal maneuvers validate the algorithm's effectiveness. 展开更多
关键词 Dynamics modeling Expectation Maximization(EM) Maneuvering target tracking Near Space Hypersonic Vehicle(NSHV) Particle Swarm Optimization(PSO)
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基于Space P和K-means的货运航司航线网络特征分析研究 认领 引用
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作者 罗凤娥 卫昌波 +1 位作者 韩晓彤 郭玲玉 《现代电子技术》 北大核心 2026年第1期102-107,共6页
针对航空货运行业的迅速扩张,航空货运网络结构变得更加复杂,文中通过Space P建模方法构建了货运航空公司航线网络模型,并运用K-means聚类算法对网络进行了深入分析。选取度、平均路径长度、聚类系数和中间度等关键网络特性指标对航线... 针对航空货运行业的迅速扩张,航空货运网络结构变得更加复杂,文中通过Space P建模方法构建了货运航空公司航线网络模型,并运用K-means聚类算法对网络进行了深入分析。选取度、平均路径长度、聚类系数和中间度等关键网络特性指标对航线网络进行层次化分类,揭示了网络的复杂特征和层次结构。通过仿真实验评估了网络的小世界特性,并利用轮廓系数得到不同K值下的聚类结果,进而确定最优聚类结果。同时,模拟了航线网络在遭受攻击时的鲁棒性,实验结果表明:在航线网络较为脆弱的情况下,该方法为货运航司航线网络的优化和抗风险能力的提升提供了重要参考。 展开更多
关键词 航空货运 Space P 航线网络 复杂网络 聚类算法 网络特征
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Enhanced corrosion of aluminum alloys induced by Aspergillus brasiliensis in space 认领 引用
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作者 Nana CHEN Tong TONG +7 位作者 Ran WANG Xiaowen SONG Zuowei FAN Zhao YIN Lin LU Ziwei HE Junxia YUAN Kui XIAO 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2026年第6期709-722,共14页
With the increasing duration of space missions,the impact of fungi on aerospace materials requires systematic investigation.We evaluate the adaptability of Aspergillus brasiliensis and its corrosion effects on aluminu... With the increasing duration of space missions,the impact of fungi on aerospace materials requires systematic investigation.We evaluate the adaptability of Aspergillus brasiliensis and its corrosion effects on aluminum alloy under space conditions through a 90-day experiment.Fungal growth characteristics,ultrastructural changes,metabolic activity,and interactions with the material surface are analyzed.The results show that Aspergillus brasiliensis maintains high adaptability to microgravity,exhibiting thickened cell walls,enhanced spore formation,and increased metabolic activity.Corrosion analysis reveals that fungal attachment accelerates localized material degradation through organic acid secretion and oxygen concentration differentials.The microgravity environment further amplifies these effects by influencing fungal metabolism and altering corrosion dynamics.Compared to ground-based conditions,space-exposed samples show significantly higher organic acid concentrations and metal ion dissolution,indicating intensified corrosion.These findings enhance the understanding of microbial corrosion mechanisms in space and provide a foundation for antifungal strategies to improve the reliability of aerospace materials during long-term missions. 展开更多
关键词 Aluminum alloys Aspergillus Microbial corrosion Microgravity Space experiment
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Federated Semi-Supervised Learning Based on Feature Space Fusion 认领 引用
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作者 Zhe Ding Hao Yi +6 位作者 Wenrui Xie Ming Zhang Yuxuan Xiao Qixu Wang Qing Chen Zhiguang Qin Dajiang Chen 《Computers, Materials & Continua》 SCIE EI 2026年第5期2062-2076,共15页
Federated semi-supervised learning(FSSL)has garnered substantial attention for enabling collaborative global model training across multiple clients to address the scarcity of labeled data and to preserve data privacy.... Federated semi-supervised learning(FSSL)has garnered substantial attention for enabling collaborative global model training across multiple clients to address the scarcity of labeled data and to preserve data privacy.However,FSSL is plagued by formidable challenges stemming fromcross-client data heterogeneity,as existing methods fail to achieve effective fusion of feature subspaces across distinct clients.To address this issue,we propose a novel FSSL framework,named FedSPQR,which is explicitly tailored for the label-at-server scenario.On the server side,FedSPQR adopts subspace clustering and fusion method based on the Grassmann manifold to construct a unified global feature space,which is further leveraged to refine the global model.On the client side,the pre-established global feature space acts as a benchmark for aligning the local feature subspaces.Based on the aligned local feature subspaces,integrating self-supervised learning with knowledge distillation facilitates effective local learning to alleviate local bias caused by data heterogeneity.Extensive experiments on two standard public benchmarks confirm that FedSPQR outperforms state-of-the-art(SOTA)baselines by a significant margin. 展开更多
关键词 Federated semi-supervised learning feature space fusion knowledge distillation
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Transformations of space electromagnetic fields in different non-inertial reference frames and their applications 认领 引用
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作者 Chao Shen Yong Ji 《Earth and Planetary Physics》 EI CSCD 2026年第2期269-279,共11页
How to transform an electromagnetic field across non-inertial frames of reference is a common challenge encountered in electromagnetic space measurements and analyses.Finding clear and precise ways to evaluate transfo... How to transform an electromagnetic field across non-inertial frames of reference is a common challenge encountered in electromagnetic space measurements and analyses.Finding clear and precise ways to evaluate transformation formulas can be difficult.This study presents results of a thorough theoretical investigation that has yielded universal transformation formulas;these transformations are successfully applied to two specific scenarios.We find that,for space plasmas,if the relative velocities of structures are significantly lower than the speed of light,Galilean transformations are suitable.The transformations presented in this paper are applicable,in low speed situations,to electromagnetic fields,electric potentials and magnetic vector potentials,and to charge density and current density,measured in various non-inertial reference frames.Truncation errors associated with these simplified transformations are calculated and shown to be acceptable.These findings have broad implications for space physics measurements and analyses.We address two key issues related to non-inertial frame transformations:first,how to derive a general formula for the rotational electric potential of planets with intrinsic magnetic fields;second,how to verify rigorously the calculation of charge density from MMS(Magnetospheric Multiscale)electrostatic field measurements.We suggest that,due to the validity of the Coulomb gauge,the Poisson equation can be applied in situations of low-speed motion,allowing MMS measurement data to be used to calculate minimal-error charge density. 展开更多
关键词 transformation of electromagnetic fields space physics charge density in space
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The diffusion and distribution of CO in confined mine spaces:A scaled experimental model approach 认领 引用
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作者 Gaofeng Shi Sheng Xue +1 位作者 Qingyi Tu Zuheng Zhao 《International Journal of Coal Science & Technology》 SCIE EI CAS CSCD 2026年第1期84-97,共14页
Diesel vehicles are the primary mode of transportation in underground coal mines,widely used in mining regions such as Inner Mongolia and Shaanxi Province,China.However,their extensive use has led to growing concerns ... Diesel vehicles are the primary mode of transportation in underground coal mines,widely used in mining regions such as Inner Mongolia and Shaanxi Province,China.However,their extensive use has led to growing concerns over diesel exhaust pollution in confined mine spaces.Carbon monoxide,a major pollutant in diesel exhaust,often results in localized concentrations exceeding 24 ppm,posing significant health risks to coal miners.This study utilizes a self-developed diesel exhaust experimental platform,with air speed as the variable,to investigate the characteristics of exhaust distribution under varying conditions.It also explores the diffusion and transport mechanisms of exhaust from diesel vehicles.The results demonstrate that CO concentration decreases with increasing distance from the exhaust source,following a"three-region"pattern.In Region I,molecular motion and concentration gradients cause a rapid reduction in CO.In Region II,convection and diffusion further dilute the CO,while in Region III,the concentration stabilizes and becomes more evenly distributed.These changes are attributed to the unique operational conditions of diesel vehicles and the fluid dynamics of exhaust diffusion.High concentrations of CO accumulate near the exhaust pipe,where dilution is slow.However,increased air speed accelerate CO reduction,with concentrations continuing to decrease as the distance from the exhaust outlet increases.The CO concentration was observed to decrease from 95.1 ppm to 9.5 ppm,a reduction of 90.01%.Comparisons of field and experimental data confirm the reliability of the experimental platform.These findings highlight the diffusion and jetting effects of CO concentration and offer engineering guidance for CO management in vehicle exhaust in coal mines. 展开更多
关键词 CO diffusion Diesel engine exhaust Confined spaces Experimental model Mine ventilation
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Development of an interpretable machine learning model for lymphovascular space invasion prediction in patients with endometrioid endometrial carcinoma:A prospective study 认领 引用
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作者 Meixuan Wu Ling Zhou +7 位作者 Xiao Yang Sihui Yang Bowen Sun Lirong Zhai Chengcheng Li Huaijun Zhou Yuan Cheng Jianliu Wang 《Chinese Journal of Cancer Research》 SCIE CAS CSCD 2026年第2期252-267,共16页
Objective: Lymphovascular space invasion(LVSI) is a high-risk factor for lymph node metastasis, relapse, and poor prognosis in patients with endometrioid endometrial carcinoma(EEC). However, the diagnosis of LVSI stil... Objective: Lymphovascular space invasion(LVSI) is a high-risk factor for lymph node metastasis, relapse, and poor prognosis in patients with endometrioid endometrial carcinoma(EEC). However, the diagnosis of LVSI still relies on traditional pathological methods. Moreover, the high-risk factors and mechanism for LVSI remain unclear. Thus, this study developed an interpretable machine learning(ML) model to accurately predict LVSI status in patients with EEC.Methods: The study collected data from 832 patients with EEC at Peking University People's Hospital. Patients were randomly divided into training(n=582) and internal validation(n=250) cohorts. A prospective external validation cohort included 129 patients with EEC from Nanjing Drum Tower Hospital. Using 21 parameters, 6 ML strategies were used to build prediction models. The global and local interpretation of feature significance was performed using the SHapley Additive exPlanations(SHAP) approach. Data from NanoString nCounter evaluation was subjected to pathway enrichment and Spearman correlation analysis to investigate the mechanistic basis of LVSI.Results: Among the six ML models, the XGBoost model had the best performance. The XGBoost model correctly predicted the risk of LVSI in the training set [area under the curve(AUC): 0.982, 95% confidence interval(95% CI): 0.972-0.991], the internal validation set(AUC: 0.818, 95% CI: 0.776-0.860), and the external test set(AUC: 0.748, 95% CI: 0.618-0.879). The calibration curve indicated that the XGBoost model exhibited favorable consistency between the predicted and actual risks. SHAP analysis identified age, carbohydrate antigen 125(CA125), low-density lipoprotein(LDL), and neutrophil as the top four variables contributing to XGBoost model predictions. Analysis of NanoString data indicated that LVSI may be closely associated with the PI3K-Akt signaling pathway.Conclusions: We developed an interpretable ML model for preoperative LVSI risk prediction in patients with EEC. This model may aid clinicians by informing individualized clinical decision-making. 展开更多
关键词 Endometrioid endometrial carcinoma lymphovascular space invasion machine learning SHAP method NanoString technology
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THE BOUNDEDNESS OF INHOMOGENEOUS CALDERÓN-ZYGMUND CONVOLUTION OPERATORS ON LOCAL PRODUCT HARDY SPACES 认领 引用
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作者 Shaoyong HE Jiecheng CHEN 《Acta Mathematica Scientia》 SCIE CSCD 2026年第1期99-111,共13页
It is well known that the inhomogeneous Calderón-Zygmund convolution operators are bounded on the local Hardy spaces.In this paper,we prove that these operators are bounded on the local product Hardy spaces and t... It is well known that the inhomogeneous Calderón-Zygmund convolution operators are bounded on the local Hardy spaces.In this paper,we prove that these operators are bounded on the local product Hardy spaces and the Lipschitz spaces.The key ideas used here are the discrete local Calderón identity and a density argument for the inhomogeneous product Lipschitz spaces in the weak sense. 展开更多
关键词 local Hardy space Lipschitz space inhomogeneous Calderón-Zygmund operator discrete Calderón identity
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WEIGHTED VARIABLE LEBESGUE SPACES AND ABSTRACT MEASURE SPACES 认领 引用
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作者 Songbai WANG Haiyan ZHOU Jiang ZHOU 《Acta Mathematica Scientia》 SCIE CSCD 2026年第3期1054-1083,共30页
Given a measure space with a ball-basis,we introduce a class of global log-Hölder continuity conditions for variable exponent functions,and we show that the Hardy-Littlewood maximal operator is bounded on weighte... Given a measure space with a ball-basis,we introduce a class of global log-Hölder continuity conditions for variable exponent functions,and we show that the Hardy-Littlewood maximal operator is bounded on weighted variable Lebesgue spaces if and only if the weights satisfy the variable Muckenhoupt condition.As an application,in virtue of extrapolation we establish the weighted norm inequalities for a class of bounded oscillation operators on these variable Lebesgue spaces. 展开更多
关键词 weighted Lebesgue space abstract measure Hardy-Littlewood maximal function extrapolation
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Hydraulic-mechanical analysis of induced stress change in unconventional reservoirs using a novel fundamental solution of poromechanics in a half space 认领 引用
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作者 Shihao Wang Ouassim Khebzegga 《Petroleum Science》 SCIE EI CAS CSCD 2026年第5期2773-2792,共20页
The production of fractured unconventional reservoirs induces stress changes,which will affect the productionperformance of neighboring wells.To quantify such effects,the analytical solution is a convenient yet accura... The production of fractured unconventional reservoirs induces stress changes,which will affect the productionperformance of neighboring wells.To quantify such effects,the analytical solution is a convenient yet accurate tool.In thiswork,we have developed an analyticalsolution of the transient pressure and stress variation induced by the production of apoint/line/plane source in a semi-infinite poroelastic reservoir with a traction-free surface boundary.We have benchmarked the derived solution with both analytical solution and numerical program.The solution demonstrates excellent accuracy.Moreover,the analytical approach reduces the computational time of numerical approaches from hours to seconds.We then apply the solution to study the surface subsidence control and stress interference between fractured horizontal wells.Results show that the derived solution is capable of quantifying complex hydraulic-mechanical processes during the recovery of shallow water as well asdeep shale reservoirs.Upon investigation,we have found that infill wells can effectively reduce the surface subsidence induced by the production of shallow horizontal wells.Furthermore,shale reservoirs with lower permeability are more sensitive to pressure-stress changes.The range of stress reorientation can also be efficiently quantified by the developed approach.Also,normal stresses and shear stresses behave differently during fracture driven interactions.The above findings potentially benefit the decisionmaking in the asset development.The major novelty of our work lies in the extension of existing approaches that are limited to axisymmetric problems to line and plane sourcesproblems,so that the solution can be used in unconventional reservoirs with fractures. 展开更多
关键词 Fundamental solution Geomechanics Poroelasticity Unconventional reservoirs Half space
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How would travel contexts affect people’s perceptions and evaluations of urban green space? 认领 引用
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作者 Yang Liu Jianying Wang +2 位作者 Mei-Po Kwan Dong Liu Liuyi Song 《Geography and Sustainability》 CSCD 2026年第2期102-115,共14页
Urban green space may impact human health through complex pathways and the effect can vary across different travel contexts.Revealing these disparities in health pathways between different travel contexts may provide ... Urban green space may impact human health through complex pathways and the effect can vary across different travel contexts.Revealing these disparities in health pathways between different travel contexts may provide essential and practical suggestions for sustainable developments in urban environments.In this study,we investi gated the impacts of travel contexts on people’s perceptions and evaluations of green space using a cross-sectional dataset collected in Hong Kong,China.Eight hundred participants in 4 representative communities were recruited through stratified sampling,and we identified 2,913 travel events from their two-day activity-travel diaries after rigorous cross-validation with GPS-derived trajectories.We also derived two green space exposure representa tions using fine-grained remote sensing imagery and 8 representative green space exposure indicators.Eighty logistical regression models and mixed-effects models were developed to investigate the associations with con trol of a range of potential uncertainties.Our results indicate solid and consistently positive associations between participants’measured green space exposure and perceived green space,and significant but variable effects of travel purposes,travel modes,and travel time on participants’perceptions and evaluations of green space.Walk ing significantly promotes participants’perceptions and positive evaluations of urban green space,buses are not significantly associated,and metro trains may depress the perception and evaluation.Our results provide solid evidence on how travel contexts may influence people’s perceptions and evaluations of urban green space and,thus,provide essential insights into environmental health studies and sustainable urban planning that consider green space as an important urban environmental setting. 展开更多
关键词 Green space Perception and evaluation Exposure measurements Travel contexts Urban planning Well-being
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Topology of the d-dimensional charged AdS black holes with a cloud of strings and quintessence in restricted phase space 认领 引用
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作者 Shan-Xia Bao Zhen-Ju Wan Yun-Zhi Du 《Communications in Theoretical Physics》 SCIE CAS CSCD 2026年第1期112-125,共14页
Based on the idea of treating the anti de Sitter(AdS)radius as a fixed parameter,we study the thermodynamics and topology of d-dimensional charged AdS black holes in the restricted phase space utilizing Visser’s holo... Based on the idea of treating the anti de Sitter(AdS)radius as a fixed parameter,we study the thermodynamics and topology of d-dimensional charged AdS black holes in the restricted phase space utilizing Visser’s holographic approach.For the charged black hole with a cloud of strings and quintessence in the higher-dimensional spacetimes with d=(4,5,6),we demonstrate that the topological number remains invariant within the same canonical ensemble;however,a distinct topological number emerges in the grand canonical ensemble for the same black hole system.Notably,these results are independent of the dimension d and other related parameters.The formalism known as restricted phase space thermodynamics is checked in detail and some interesting thermodynamic behavior is revealed in the example case of d-dimensional charged AdS black holes with a cloud of strings and quintessence.This research lays the foundation for establishing a universal framework of restricted phase space thermodynamics and investigating its fundamental thermodynamic properties. 展开更多
关键词 topology charged AdS black hole restricted phase space
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Octonions and 7-dimensional space vector transformation 认领 引用
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作者 Liang Lingfeng Zhang Hanwei +1 位作者 Li Kezhao Zhang Hua 《Applied Geophysics》 SCIE CSCD 2026年第1期380-390,434,共11页
An afne space is a set consisting of points and vectors.A vector space(or linear space)is an afne space with a specied origin.For a given afne coordinate system,there exists a one-to-one correspondence between vectors... An afne space is a set consisting of points and vectors.A vector space(or linear space)is an afne space with a specied origin.For a given afne coordinate system,there exists a one-to-one correspondence between vectors and coordinates.In order to provide a theoretical basis for coordinate and frame transformations,and to simplify the transformation process in specic problem studies,the geometric product of vectors is redened(the geometric product of vectors is the sum of the negative inner product and the outer product of the vectors),thus the one-to-one correspondence relationship between unit vectors and imaginary units is established.According to Hurwitz's theorem,the vector space of the outer product is gotten and dened,and its dimension cannot be chosen arbitrarily.Based on Arthur Cayley's(1845)multiplication rules of octonions,transformation formulas for a seven-dimensional vector space and rotation matrices for coordinate frame transformations are derived.It is pointed out that the three-dimensional rotation matrices commonly used in astrometry and geodesy are special cases thereof.According to the redefinition of the geometric product of vectors,the multiplication rules of quaternions can be directly obtained,as well as the multiplication table of imaginary units of octonions.It is further indicated that the multiplication tables of imaginary units for octonions and hypercomplex numbers of higher dimensions are not unique. 展开更多
关键词 Octonions 7-dimensional vector spaces Coordinate or frame transformations Rotation matrices
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A novel dexterity optimization scheme with kinematic uncertainty handling capability for redundant space manipulators 认领 引用
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作者 Xiaohang YANG Dongxu CHEN +2 位作者 Zhiyuan ZHAO Jingdong ZHAO Hong LIU 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2026年第1期643-655,共13页
In the construction and maintenance for large space equipment,it is essential to ensure the control accuracy and improve the dexterity of the space manipulator.In this paper,a FiniteTime Convergence Kinematic Control(... In the construction and maintenance for large space equipment,it is essential to ensure the control accuracy and improve the dexterity of the space manipulator.In this paper,a FiniteTime Convergence Kinematic Control(FTCKC)added with Acceleration Level Dexterity Optimization(ALDO)scheme is proposed to solve the kinematic uncertainty and dexterity optimization problems of redundant space manipulators.Concretely,distinguishing from the asymptotic convergence property of traditional adaptive Jacobian methods,the FTCKC scheme is adopted to construct the equality constraint to address the model uncertainty problem,and its error can converge within a finite time.Subsequently,the dexterity index is reconstructed at acceleration level by a multi-level target handling method.Then,the equality constraint,optimization task,and limit constraints are reformulated as a quadratic programming problem.Moreover,a Recurrent Neural Network(RNN)is engineered for the constructed FTCKC-ALDO scheme.Finally,the superiority of the FTCKC-ALDO-RNN scheme is verified by experiments. 展开更多
关键词 Dexterity optimization Model uncertainty Recurrent Neural Network(RNN) Trajectory tracking Large space equipment
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Boundedness of Pesudo-differential Operators on Besov Spaces 认领 引用
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作者 DAI Jiawei LU Yanfei +1 位作者 ZHENG Ruxiu HUANG Qiang 《数学进展》 CSCD 北大核心 2026年第3期578-588,共11页
In this paper,we investigate the boundedness of pseudo-differential operators Tαon Besov spaces Bp,qswith symbol a∈Sρ,δm,0≤ρ≤δ<1.We obtain that Tαis bounded from Bp,qs+m-mc(p)to ... In this paper,we investigate the boundedness of pseudo-differential operators Tαon Besov spaces Bp,qswith symbol a∈Sρ,δm,0≤ρ≤δ<1.We obtain that Tαis bounded from Bp,qs+m-mc(p)to Bp,qs,where■. 展开更多
关键词 pseudo-differential operator Besov space Hörmander class
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NONLINEAR RIEMANN AND HILBERT BOUNDARY VALUE PROBLEMS WITH SQUARE ROOTS IN VARIABLE EXPONENT SPACES 认领 引用
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作者 Yajun Hu Fuli He 《Acta Mathematica Scientia》 SCIE CSCD 2026年第1期1-18,共18页
In this paper,we study the nonlinear Riemann boundary value problem with square roots that is represented by a Cauchy-type integral with kernel density in variable exponent Lebesgue spaces.We discuss the odd-order zer... In this paper,we study the nonlinear Riemann boundary value problem with square roots that is represented by a Cauchy-type integral with kernel density in variable exponent Lebesgue spaces.We discuss the odd-order zero-points distribution of the solutions and separate the single valued analytic branch of the solutions with square roots,then convert the problem to a Riemann boundary value problem in variable exponent Lebesgue spaces and discuss the singularity of solutions at individual zeros belonging to curve.We consider two types of cases those where the coefficient is Hölder and those where it is piecewise Hölder.Then we solve the Hilbert boundary value problem with square roots in variable exponent Lebesgue spaces.By discussing the distribution of the odd-order zero-points for solutions and the method of symmetric extension,we convert the Hilbert problem to a Riemann boundary value problem.The equivalence of the transformation is discussed.Finally,we get the solvable conditions and the direct expressions of the solutions in variable exponent Lebesgue spaces. 展开更多
关键词 boundary value problem Cauchy-type integral variable exponent spaces non-linearity piecewise Lyapunov curve
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