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Strong Laws of Large Numbers for Sequences of Blockwise m-Dependent and Sub-Orthogonal Random Variables under Sublinear Expectations 被引量:1
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作者 Jialiang FU 《Journal of Mathematical Research with Applications》 2026年第1期103-118,共16页
In this paper,we establish some strong laws of large numbers,which are for nonindependent random variables under the framework of sublinear expectations.One of our main results is for blockwise m-dependent random vari... In this paper,we establish some strong laws of large numbers,which are for nonindependent random variables under the framework of sublinear expectations.One of our main results is for blockwise m-dependent random variables,and another is for sub-orthogonal random variables.Both extend the strong law of large numbers for independent random variables under sublinear expectations to the non-independent case. 展开更多
关键词 sublinear expectations strong law of large numbers blockwise m-dependent suborthogonal random variables
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A data-and expert-driven framework for establishing land cover-related essential variables for SDG monitoring and assessment
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作者 Hao Wu Ping Zhang +6 位作者 Jun Chen Songnian Li Jing Li Shu Peng Dongyang Hou Jun Zhang Hao Chen 《Geography and Sustainability》 2026年第1期236-246,共11页
Sustained and spatially explicit monitoring of the United Nations 2030 Agenda for Sustainable Development is critical for effectively tracking progress toward the global Sustainable Development Goals(SDGs).Although la... Sustained and spatially explicit monitoring of the United Nations 2030 Agenda for Sustainable Development is critical for effectively tracking progress toward the global Sustainable Development Goals(SDGs).Although land cover information has long been recognized as an essential component for monitoring SDGs,a standardized scientific framework for identifying and prioritizing land cover related essential variables does not exist.Therefore,we propose a novel expert-and data-driven framework for identifying,refining,and selecting a priority list of Essential Land cover-related Variables for SDGs(ELcV4SDGs).This framework integrates methods including expert knowledge-based analysis,clustering of variables with similar attributes,and quantified index calculation to establish the priority list.Applying the framework to 15 specific SDG indicators,we found that the ELcV4SDGs priority list comprises three main categories,type and structure,pattern and intensity,and process and evolution of land cover,which are further divided into 19 subcategories and ultimately encompass 50 general variables.The ELcV4SDGs will support detailed spatial monitoring and enhance their scientific applications for SDG monitoring and assessment,thereby guiding future SDG priority actions and informing decision-making to advance the 2030 SDGs agenda at local,national,and global levels. 展开更多
关键词 Essential variable Land cover SDG Spatial monitoring and assessment Interactive analysis Refinement and selection
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Optimizing Fine-Tuning in Quantized Language Models:An In-Depth Analysis of Key Variables
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作者 Ao Shen Zhiquan Lai +1 位作者 Dongsheng Li Xiaoyu Hu 《Computers, Materials & Continua》 SCIE EI 2025年第1期307-325,共19页
Large-scale Language Models(LLMs)have achieved significant breakthroughs in Natural Language Processing(NLP),driven by the pre-training and fine-tuning paradigm.While this approach allows models to specialize in speci... Large-scale Language Models(LLMs)have achieved significant breakthroughs in Natural Language Processing(NLP),driven by the pre-training and fine-tuning paradigm.While this approach allows models to specialize in specific tasks with reduced training costs,the substantial memory requirements during fine-tuning present a barrier to broader deployment.Parameter-Efficient Fine-Tuning(PEFT)techniques,such as Low-Rank Adaptation(LoRA),and parameter quantization methods have emerged as solutions to address these challenges by optimizing memory usage and computational efficiency.Among these,QLoRA,which combines PEFT and quantization,has demonstrated notable success in reducing memory footprints during fine-tuning,prompting the development of various QLoRA variants.Despite these advancements,the quantitative impact of key variables on the fine-tuning performance of quantized LLMs remains underexplored.This study presents a comprehensive analysis of these key variables,focusing on their influence across different layer types and depths within LLM architectures.Our investigation uncovers several critical findings:(1)Larger layers,such as MLP layers,can maintain performance despite reductions in adapter rank,while smaller layers,like self-attention layers,aremore sensitive to such changes;(2)The effectiveness of balancing factors depends more on specific values rather than layer type or depth;(3)In quantization-aware fine-tuning,larger layers can effectively utilize smaller adapters,whereas smaller layers struggle to do so.These insights suggest that layer type is a more significant determinant of fine-tuning success than layer depth when optimizing quantized LLMs.Moreover,for the same discount of trainable parameters,reducing the trainable parameters in a larger layer is more effective in preserving fine-tuning accuracy than in a smaller one.This study provides valuable guidance for more efficient fine-tuning strategies and opens avenues for further research into optimizing LLM fine-tuning in resource-constrained environments. 展开更多
关键词 Large-scale Language Model Parameter-Efficient Fine-Tuning parameter quantization key variable trainable parameters experimental analysis
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Complete f-Moment Convergence for Sung’s Type Weighted Sums of Negatively Superadditive Dependent Random Variables
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作者 HU Xueping WANG Liuliu +1 位作者 HU Ke XU Zhonghao 《应用概率统计》 北大核心 2025年第4期585-601,共17页
In this paper,by utilizing the Marcinkiewicz-Zygmund inequality and Rosenthal-type inequality of negatively superadditive dependent(NSD)random arrays and truncated method,we investigate the complete f-moment convergen... In this paper,by utilizing the Marcinkiewicz-Zygmund inequality and Rosenthal-type inequality of negatively superadditive dependent(NSD)random arrays and truncated method,we investigate the complete f-moment convergence of NSD random variables.We establish and improve a general result on the complete f-moment convergence for Sung’s type randomly weighted sums of NSD random variables under some general assumptions.As an application,we show the complete consistency for the randomly weighted estimator in a nonparametric regression model based on NSD errors. 展开更多
关键词 Marcinkiewicz-Zygmund inequality Rosenthal-type inequality Sung’s type randomly weighted sums negatively superadditive dependent random variables complete f-moment convergence
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Equivalent Conditions of Complete Convergence for Weighted Sums of Sequences of i.i.d.Random Variables under Sublinear Expectations
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作者 XU Mingzhou CHENG Kun 《应用概率统计》 北大核心 2025年第3期339-352,共14页
The complete convergence for weighted sums of sequences of independent,identically distributed random variables under sublinear expectation space is studied.By moment inequality and truncation methods,we establish the... The complete convergence for weighted sums of sequences of independent,identically distributed random variables under sublinear expectation space is studied.By moment inequality and truncation methods,we establish the equivalent conditions of complete convergence for weighted sums of sequences of independent,identically distributed random variables under sublinear expectation space.The results complement the corresponding results in probability space to those for sequences of independent,identically distributed random variables under sublinear expectation space. 展开更多
关键词 complete convergence weighted sums i.i.d.random variables sublinear expectation
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Influence of ambient geochemical and microbiological variables on the bacterial diversity in a cold seep ecosystem in North Indian Ocean
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作者 Delcy R.Nazareth Maria Judith Gonsalves Nitisha Sangodkar 《Geoscience Frontiers》 2025年第3期153-163,共11页
Cold seeps are oases for biological communities on the sea floor around hydrocarbon emission pathways.Microbial utilization of methane and other hydrocarbons yield products that fuel rich chemosynthetic communities at... Cold seeps are oases for biological communities on the sea floor around hydrocarbon emission pathways.Microbial utilization of methane and other hydrocarbons yield products that fuel rich chemosynthetic communities at these sites.One such site in the cold seep ecosystem of Krishna-Godavari basin(K-G basin)along the east coast of India,discovered in Feb 2018 at a depth of 1800 m was assessed for its bacterial diversity.The seep bacterial communities were dominated by phylum Proteobacteria(57%),Firmicutes(16%)and unclassified species belonging to the family Helicobacteriaceae.The surface sediments of the seep had maximum OTUs(operational taxonomic units)(2.27×10^(3))with a Shannon alpha diversity index of 8.06.In general,environmental parameters like total organic carbon(p<0.01),sulfate(p<0.001),sulfide(p<0.05)and methane(p<0.01)were responsible for shaping the bacterial community of the cold seep ecosystem in the K-G Basin.Environmental parameters play a significant role in changing the bacterial diversity richness between different cold seep environments in the oceans. 展开更多
关键词 SEDIMENTS Environmental variables PROTEOBACTERIA Cold seep ecosystem Organic matter
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Mapping soil organic carbon in fragmented agricultural landscapes:The efficacy and interpretability of multi-category remote sensing variables
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作者 Yujiao Wei Yiyun Chen +6 位作者 Jiaxue Wang Peiheng Yu Lu Xu Chi Zhang Huanfeng Shen Yaolin Liu Ganlin Zhang 《Journal of Integrative Agriculture》 2025年第11期4395-4414,共20页
Accurately mapping the spatial distribution of soil organic carbon(SOC)is crucial for guiding agricultural management and improving soil carbon sequestration,especially in fragmented agricultural landscapes.Although r... Accurately mapping the spatial distribution of soil organic carbon(SOC)is crucial for guiding agricultural management and improving soil carbon sequestration,especially in fragmented agricultural landscapes.Although remote sensing provides spatially continuous environmental information about heterogeneous agricultural landscapes,its relationship with SOC remains unclear.In this study,we hypothesized that multi-category remote sensing-derived variables can enhance our understanding of SOC variation within complex landscape conditions.Taking the Qilu Lake watershed in Yunnan,China,as a case study area and based on 216 topsoil samples collected from irrigation areas,we applied the extreme gradient boosting(XGBoost)model to investigate the contributions of vegetation indices(VI),brightness indices(BI),moisture indices(MI),and spectral transformations(ST,principal component analysis and tasseled cap transformation)to SOC mapping.The results showed that ST contributed the most to SOC prediction accuracy,followed by MI,VI,and BI,with improvements in R2 of 29.27,26.83,19.51,and 14.43%,respectively.The dominance of ST can be attributed to the fact that it contains richer remote sensing spectral information.The optimal SOC prediction model integrated soil properties,topographic factors,location factors,and landscape metrics,as well as remote sensing-derived variables,and achieved RMSE and MAE of 15.05 and 11.42 g kg-1,and R2 and CCC of 0.57 and 0.72,respectively.The Shapley additive explanations deciphered the nonlinear and threshold effects that exist between soil moisture,vegetation status,soil brightness and SOC.Compared with traditional linear regression models,interpretable machine learning has advantages in prediction accuracy and revealing the influences of variables that reflect landscape characteristics on SOC.Overall,this study not only reveals how remote sensing-derived variables contribute to our understanding of SOC distribution in fragmented agricultural landscapes but also clarifies their efficacy.Through interpretable machine learning,we can further elucidate the causes of SOC variation,which is important for sustainable soil management and agricultural practices. 展开更多
关键词 soil organic carbon remote sensing-derived variables Shapley additive explanations efficacy and interpretability fragmented agricultural landscapes
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A Decision Variables Classification-Based Evolutionary Algorithm for Constrained Multi-Objective Optimization Problems
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作者 Xuanxuan Ban Jing Liang +4 位作者 Kangjia Qiao Kunjie Yu Yaonan Wang Jinzhu Peng Boyang Qu 《IEEE/CAA Journal of Automatica Sinica》 2025年第9期1830-1849,共20页
Solving constrained multi-objective optimization problems(CMOPs)is a challenging task due to the presence of multiple conflicting objectives and intricate constraints.In order to better address CMOPs and achieve a bal... Solving constrained multi-objective optimization problems(CMOPs)is a challenging task due to the presence of multiple conflicting objectives and intricate constraints.In order to better address CMOPs and achieve a balance between objectives and constraints,existing constrained multi-objective evolutionary algorithms(CMOEAs)predominantly focus on devising various strategies by leveraging the relationships between objectives and constraints,and the designed strategies usually are effective for the problems with simple constraints.However,these methods most ignore the relationship between decision variables and constraints.In fact,the essence of optimization is to find appropriate decision variables to meet various complex constraints.Therefore,it is hoped that the problem can be analyzed from the perspective of decision variables,so as to obtain more excellent results.Based on the above motivation,this paper proposes a decision variables classification approach,according to the relationship between decision variables and constraints,variables are divided into constraint-related(CR)variables and constraintindependent(CI)variables.Consequently,by optimizing these two types of variables independently,the population can sustain a favorable balance between feasibility and diversity.Furthermore,specific offspring generation strategies are proposed for the two categories of decision variables in order to achieve rapid convergence while maintaining population diversity.Experimental results on 31 test problems as well as 20 real-world problems demonstrate that the proposed algorithm is competitive compared to some state-of-the-art constrained multi-objective optimization algorithms. 展开更多
关键词 Constraint-independent(CI) constrained multiobjective optimization constraint-related(CR) decision variables
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On α-Bloch Functions in Several Complex Variables
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作者 ZHU Ting YANG Liu 《Chinese Quarterly Journal of Mathematics》 2025年第1期93-102,共10页
In this paper,we establish characterizations of α-Bloch functions and little α-Bloch functions on the unit ball as well as the unit polydisk of C^(m),which generalize and improve results of Aulaskari-Lappan,Minda,Au... In this paper,we establish characterizations of α-Bloch functions and little α-Bloch functions on the unit ball as well as the unit polydisk of C^(m),which generalize and improve results of Aulaskari-Lappan,Minda,Aulaskari-Wulan,and Wu.Some examples are also given to complement our theory. 展开更多
关键词 α-Bloch function Littleα-Bloch function Several complex variables Partial derivative
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Complete q-Order Moment Convergence of Moving Average Processes Generated by Negatively Dependent Random Variables under Sub-Linear Expectations
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作者 Mingzhou XU 《Journal of Mathematical Research with Applications》 2025年第3期395-410,共16页
Assume that{a_(i),−∞<i<∞}is an absolutely summable sequence of real numbers.We establish the complete q-order moment convergence for the partial sums of moving average processes{X_(n)=Σ_(i=−∞)^(∞)a_(i)Y_(i+... Assume that{a_(i),−∞<i<∞}is an absolutely summable sequence of real numbers.We establish the complete q-order moment convergence for the partial sums of moving average processes{X_(n)=Σ_(i=−∞)^(∞)a_(i)Y_(i+n),n≥1}under some proper conditions,where{Yi,-∞<i<∞}is a doubly infinite sequence of negatively dependent random variables under sub-linear expectations.These results extend and complement the relevant results in probability space. 展开更多
关键词 moving average processes negatively dependent random variables complete moment convergence sub-linear expectations
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Methods of Selecting Adaptive Artificial Viscosity in Completely Conservative Difference Schemes for Gas Dynamics Equations in Euler Variables
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作者 Marina Ladonkina Viktoriia Podryga +1 位作者 Yury Poveshchenko Haochen Zhang 《Frontiers in Heat and Mass Transfer》 2025年第6期1789-1809,共21页
The work presents new methods for selecting adaptive artificial viscosity(AAV)in iterative algorithms of completely conservative difference schemes(CCDS)used to solve gas dynamics equations in Euler variables.These me... The work presents new methods for selecting adaptive artificial viscosity(AAV)in iterative algorithms of completely conservative difference schemes(CCDS)used to solve gas dynamics equations in Euler variables.These methods allow to effectively suppress oscillations,including in velocity profiles,as well as computational instabilities in modeling gas-dynamic processes described by hyperbolic equations.The methods can be applied both in explicit and implicit(method of separate sweeps)iterative processes in numerical modeling of gas dynamics in the presence of heat and mass transfer,as well as in solving problems of magnetohydrodynamics and computational astrophysics.In order to avoid loss of solution accuracy on spatially non-uniform grids,in this work an algorithm of grid embeddings is developed,which is applied near transition points between cells of different sizes.The developed algorithms of CCDS using the methods for AAV selection and the algorithm of grid embeddings are implemented for various iterative processes.Calculations are performed for the classical problem of decay of an arbitrary discontinuity(Sod’s problem)and the problem of propagation of two symmetric rarefaction waves in opposite directions(Einfeldt’s problem).In the case of using different methods for selecting the AAV,a comparison of the solutions of the Sod’s problem on uniform and non-uniform grids and a comparison of the solutions of the Einfeldt’s problem on a uniform grid are performed.As a result of the comparative analysis,the applicability of these methods is shown in the spatially one-dimensional case(explicit and implicit iterative processes).The obtained results are compared with the data from the literature.The results coincide with analytical solutions with high accuracy,where the relative error does not exceed 0.1%,which demonstrates the effectiveness of the developed algorithms and methods. 展开更多
关键词 Gas dynamics adaptive artificial viscosity equations in Euler variables completely conservative differ-ence schemes heat and mass transfer
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A Study of Cataclysmic Variables from the eFEDS Survey
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作者 Rui Wang Wei-Min Gu +3 位作者 Zhi-Xiang Zhang Tuan Yi Senyu Qi Xiao-Jie Xu 《Research in Astronomy and Astrophysics》 2025年第11期46-57,共12页
We present 17 cataclysmic variables(CVs) obtained from the crossmatch between the Sloan Digital Sky Survey(SDSS) and eROSITA Final Equatorial Depth Survey(eFEDS),including eight known CVs before eFEDS and nine identif... We present 17 cataclysmic variables(CVs) obtained from the crossmatch between the Sloan Digital Sky Survey(SDSS) and eROSITA Final Equatorial Depth Survey(eFEDS),including eight known CVs before eFEDS and nine identified from eFEDS.The photometric periods of four CVs are derived from the Zwicky Transient Facility and Catalina Real-Time Transient Survey.We focus on two CVs,SDSS J084309.3-014858 and SDSS J093555.0+042916,and confirm that their photometric periods correspond to the orbital periods by fitting the radial velocity curves.Furthermore,by the combination of the Gaia distance,the spectral energy distribution,and the variations of Ha emission lines,the masses of the white dwarf and the visible star can be well constrained. 展开更多
关键词 (stars:)binaries(including multiple):close (stars:)novae cataclysmic variables X-rays:binaries
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Complete Convergence for the Maximum Partial Sums of m-Widely Orthant Dependent Random Variables Sequences
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作者 SONG Mingzhu 《Wuhan University Journal of Natural Sciences》 2025年第6期549-557,共9页
In this paper,the author obtains complete convergence for the maximum partial sums of m-widely orthant dependent(m-WOD)random variables sequences under some general conditions.The results extend the complete convergen... In this paper,the author obtains complete convergence for the maximum partial sums of m-widely orthant dependent(m-WOD)random variables sequences under some general conditions.The results extend the complete convergence for m-WOD random variables to a much more general type complete convergence.As the sequences of m-WOD random variables represent a very broad class of dependent sequences,the results improve and generalize the corresponding ones in the literature. 展开更多
关键词 m-WOD random variables complete convergence Spitzer’s law of large numbers
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On the Spatial Distribution of Luminous Blue Variables in the Galaxy M33
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作者 A.Kostenkov S.Fabrika +6 位作者 A.Kaldybekova S.Fedorchenko Y.Solovyeva E.Dedov A.Sarkisyan A.Vinokurov O.Sholukhova 《Research in Astronomy and Astrophysics》 2025年第4期136-149,共14页
In the current paper,we present a study of the spatial distribution of luminous blue variables(LBVs)and various LBV candidates(c LBVs)with respect to OB associations in the galaxy M33.The identification of blue star g... In the current paper,we present a study of the spatial distribution of luminous blue variables(LBVs)and various LBV candidates(c LBVs)with respect to OB associations in the galaxy M33.The identification of blue star groups was based on the LGGS data and was carried out by two clustering algorithms with initial parameters determined during simulations of random stellar fields.We have found that the distribution of distances to the nearest OB association obtained for the LBV/c LBV sample is close to that for massive stars with Minit>20 M⊙and WolfRayet stars.This result is in good agreement with the standard assumption that LBVs represent an intermediate stage in the evolution of the most massive stars.However,some objects from the LBV/cLBV sample,particularly Fe II-emission stars,demonstrated severe isolation compared to other massive stars,which,together with certain features of their spectra,implicitly indicates that the nature of these objects and other LBVs/cLBVs may differ radically. 展开更多
关键词 stars:massive stars:evolution stars:winds outflows stars:variables:S Doradus (stars:)binaries:general galaxies:individual(M33)
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MJO年代际变化的研究进展与科学思考 被引量:1
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作者 王璐 纪小末 +3 位作者 徐邦琪 李天明 陈林 陆波 《大气科学学报》 北大核心 2026年第1期208-216,共9页
Madden-Julian Oscillation(MJO)是热带大气最重要的季节内变率模态,其年代际变化不仅反映了热带气候系统的非平稳性特征,也直接影响其作为延伸期预报因子的有效性。本文系统综述了近年来关于MJO强度和传播特征年代际变化的研究进展,并... Madden-Julian Oscillation(MJO)是热带大气最重要的季节内变率模态,其年代际变化不仅反映了热带气候系统的非平稳性特征,也直接影响其作为延伸期预报因子的有效性。本文系统综述了近年来关于MJO强度和传播特征年代际变化的研究进展,并总结了主要科学认识。结果表明,MJO在强度、传播速度和传播范围方面均存在显著的年代际变化,同时具有明显的区域性与季节性差异。强度变化最显著的区域集中在西太平洋暖池,与局地海温升高密切相关;传播速度表现为印度洋MJO东传加快而西太平洋和海洋性大陆区域减慢,其区域性差异主要归因于热带海温增暖的不对称性;传播范围受跨洋盆模态调制,尤其是大西洋多年代际振荡(Atlantic Multidecadal Oscillation,AMO),不同位相下MJO的空间范围及对流-环流耦合持续时间显著不同。MJO年代际变化受多尺度过程协同调制,包括局地海气耦合、背景环流变化及对流-环流正反馈放大等非线性过程。尽管观测与模式研究取得了进展,但在资料一致性、指标敏感性、机理归因及对气候可预报性的影响等方面仍存在不确定性。 展开更多
关键词 热带季节内振荡 年代际变化 强度 传播
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白浆层培肥机螺旋排肥器的设计与试验 被引量:1
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作者 李晓明 王秋菊 +5 位作者 张海滨 齐忠军 兰海涛 邹雪剑 陈维刚 梁玉成 《农机化研究》 北大核心 2026年第4期18-24,33,共8页
针对传统排肥器施肥不均匀、效率低等问题,设计了一种白浆层培肥机的螺旋排肥器。其通过精确控制绞龙叶片的数量、螺距和转速,实现了对施肥量的精准调节。利用三维软件SolidWorks 2020对螺旋排肥器建模,通过EDEM软件建立颗粒模型,并进... 针对传统排肥器施肥不均匀、效率低等问题,设计了一种白浆层培肥机的螺旋排肥器。其通过精确控制绞龙叶片的数量、螺距和转速,实现了对施肥量的精准调节。利用三维软件SolidWorks 2020对螺旋排肥器建模,通过EDEM软件建立颗粒模型,并进行虚拟仿真试验。以施肥量稳定性变异系数和均匀性变异系数为指标,结合肥料特性等因素,进行三因素三水平正交试验。采用Design-Expert分析软件对试验数据进行分析,得出最优结构参数:绞龙叶片数量为3,螺距为43 mm,绞龙叶片转速为200 r/min。此时,稳定性变异系数为1.6%,均匀性变异系数为4.51%。剔除不显著因素,建立了施肥量稳定性变异系数和均匀性变异系数的回归方程。田间试验验证表明:试验结果与仿真结果一致,符合NY/T 1003—2006《施肥机械质量评价技术规范》标准,为农业生产提供了可靠的技术支持。 展开更多
关键词 螺旋排肥器 白浆层培肥机 EDEM 变量施肥
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基于果树冠层识别的植保无人机可变角度变量喷施装置设计与试验
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作者 傅生辉 任乃旭 +3 位作者 张鑫哲 刘双喜 刘镰恺 张稳 《农业机械学报》 北大核心 2026年第3期47-56,共10页
针对当前无人机喷药喷施不均匀、雾滴飘移、肥药有效利用率低和浪费污染严重等问题,设计了一种基于果树冠层识别的植保无人机可变角度变量喷施装置。该装置通过摄像头采集果树冠层图像并传输至Jetson Orin Nano,利用ROI选取与子区间线... 针对当前无人机喷药喷施不均匀、雾滴飘移、肥药有效利用率低和浪费污染严重等问题,设计了一种基于果树冠层识别的植保无人机可变角度变量喷施装置。该装置通过摄像头采集果树冠层图像并传输至Jetson Orin Nano,利用ROI选取与子区间线扫方法实现冠层边界与果树行宽度识别,识别结果传至STM32控制器,其中冠层边界信息用于调节喷头角度,像素占比信息用于调控喷头流量,流量计与磁编码器反馈信号经模糊PID算法处理,实现喷头角度与喷施量双闭环控制。经试验验证,果树冠层边界算法离线识别率为91.58%。台架试验结果表明,该方法在果树行宽度识别中平均误差为7.32%,线性拟合R^(2)=0.91;在喷雾验证中,当喷施角度大于靶区时,调节后可使靶区外沉积数量平均降低26.61个/cm^(2),雾滴沉积数量降低51.94%。当喷施角度小于靶区时,调节后可使靶区内外部雾滴沉积数量平均提升25.37个/cm^(2),雾滴沉积数量提高54.8%。核密度估计曲线更平滑,有效改善沉积分布均匀性。田间试验结果显示:统计检验结果为t=3.29、P=0.03,达到P<0.05的统计显著水平,装置开启状态下沉积效果更优,该方法实现了基于果树行宽度可变角度变量喷施控制,可有效提高雾滴利用率,为无人机果园精准施药提供技术支持。 展开更多
关键词 植保无人机 果树行检测 可变角度变量喷雾 模糊PID 药液沉积
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汽车变刚度智能悬挂系统抑制共振H∞控制设计
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作者 黄晶晶 熊永莲 李峰 《机械设计与制造》 北大核心 2026年第3期12-16,共5页
汽车运行平稳性是目前研究的热点,为了进一步提高汽车共振抑制能力,设计了一种汽车变刚度智能悬挂系统H∞控制方案。基于汽车的车体横向共振特点设计了一种可以实现智能化控制的悬挂结构,再将其应用到了横向悬挂系统中,有效克服汽车共... 汽车运行平稳性是目前研究的热点,为了进一步提高汽车共振抑制能力,设计了一种汽车变刚度智能悬挂系统H∞控制方案。基于汽车的车体横向共振特点设计了一种可以实现智能化控制的悬挂结构,再将其应用到了横向悬挂系统中,有效克服汽车共振问题,显著提升车辆舒适度与稳定性。研究结果表明:谐波激励下,H∞智能悬挂可以达到较低振动传递率,能够有效防止被动悬挂系统出现车辆共振情况。H∞控制智能悬挂形成了比被动悬挂更小的加速度,获得约50%的减振效果。随机激励下,加入H∞控制智能悬挂后都获得了比被动悬挂系统更小的振动加速度,最大加速度减小50%,使车体振动程度减少21.4%,使乘坐舒适度提升28.2%。该研究有助于提高汽车运行平稳性,有效满足目前汽车运行的要求。 展开更多
关键词 汽车 智能悬挂 变刚度 共振抑制 H∞控制
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变分数阶混沌系统有限时间自适应滑模同步
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作者 毛北行 张伟 +2 位作者 王东晓 焦建锋 陈灿 《中山大学学报(自然科学版)(中英文)》 北大核心 2026年第2期136-143,共8页
研究降控制器变分数阶三阶三次混沌系统同步问题,利用变分数阶稳定性理论及有限时间自适应滑模同步相关结论,设计滑模函数与变分数阶自适应律,获得系统有限时间滑模同步的条件,针对三阶系统只需要设计2个控制器就能在有限时间内使变分... 研究降控制器变分数阶三阶三次混沌系统同步问题,利用变分数阶稳定性理论及有限时间自适应滑模同步相关结论,设计滑模函数与变分数阶自适应律,获得系统有限时间滑模同步的条件,针对三阶系统只需要设计2个控制器就能在有限时间内使变分数阶三阶三次混沌系统主从系统取得自适应滑模同步,从而减少了控制器个数,利用仿真算例检验结论的正确性. 展开更多
关键词 滑模 变分数阶 有限时间 混沌系统
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基于DQN的对地观测卫星调度算法
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作者 许可 孙昌浩 +1 位作者 谢睿达 夏维 《空间控制技术与应用(中英文)》 北大核心 2026年第1期68-78,共11页
面向国土资源普查的卫星任务规划问题因卫星侧摆角连续可调、时间窗规模庞大而呈高维非线性解空间,叠加强耦合资源约束,极具挑战性.本文构建基于“观测机会”的离散决策模型,将原问题解耦为观测时序排列与成像条带优选这两个子问题.针... 面向国土资源普查的卫星任务规划问题因卫星侧摆角连续可调、时间窗规模庞大而呈高维非线性解空间,叠加强耦合资源约束,极具挑战性.本文构建基于“观测机会”的离散决策模型,将原问题解耦为观测时序排列与成像条带优选这两个子问题.针对现有算法在处理此类序列优化与参数选择耦合问题时存在的规则短视和搜索低效局限,提出一种嵌入深度强化学习的变邻域搜索(VNS)调度算法.该方法构建了分层调度模型,利用VNS的多重邻域结构在宏观层面优化观测序列以跳出局部最优,同时在微观层面引入结合多维状态特征空间的DQN(deep Q-network),实现对条带选择价值的自适应评估以替代人工设计规则.仿真试验表明,所提方法兼具优异的收敛速度与求解质量,在99%的测试样本中方案得分与理论总分差距小于15%. 展开更多
关键词 卫星任务规划 变邻域搜索 深度强化学习
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