期刊文献+
共找到1,351篇文章
< 1 2 68 >
每页显示 20 50 100
Re-Entry of Space Objects from Low Eccentricity Orbits
1
作者 Cynthia Sharon Lawrence Ram Krishan Sharma 《International Journal of Astronomy and Astrophysics》 2019年第3期200-216,共17页
This paper deals with the re-entry predictions of the space objects from the low eccentric orbit. Any re-entering object re-enters the Earth’s atmosphere with a high orbital velocity. Due to the aerodynamic heating t... This paper deals with the re-entry predictions of the space objects from the low eccentric orbit. Any re-entering object re-enters the Earth’s atmosphere with a high orbital velocity. Due to the aerodynamic heating the object tends to break into multiple fragments which later pose a great risk hazard to the population. Here a satellite is considered as the space object for which the re-entry prediction is made. This prediction is made with a package where the trajectory path, the time of re-entry and the survival rate of the fragments is done. The prediction is done using DRAMA 2.0—ESA’s Debris Risk Assessment and Mitigation Analysis Tool suite, MATLAB and Numerical Prediction of Orbital Events software. The predicted re-entry time of OSIRIS 3U was found to be on 7th March 2019, 7:25 (UTC), whereas the actual re-entry time was on 7th March 2019, 7:03 (UTC). The trajectory path found was 51.5699 deg. (Lat), &minus;86.5738 deg. (Long.) with an altitude of 168.643 km. But the actual trajectory was 51.76 deg. (Lat), &minus;89.01deg. (Long.) with an altitude of 143.5 km. 展开更多
关键词 RE-ENTRY space objects Low Eccentricity Orbits DRAMA 2.0 Risk Event Statistics
下载PDF
Research of Modeling Moving Objects Database over Space-time Grid
2
作者 Hongtao Yu Zhongcheng Yu 《通讯和计算机(中英文版)》 2010年第3期64-68,共5页
关键词 移动对象数据库 网格模型 空时 建模 动态信息 数据库技术 运动物体 移动物体
下载PDF
自由漂浮空间机器人捕获翻滚目标的力-位-型融合控制方法
3
作者 梁斌 徐文福 +1 位作者 王学谦 闫磊 《宇航学报》 EI CAS CSCD 北大核心 2024年第6期958-969,共12页
翻滚目标捕获过程中,空间机器人的运动会对基座产生扰动、接触过程的冲击碰撞容易产生安全风险。因此,为了在捕获翻滚目标的同时抑制空间机械臂对基座的扰动和对目标的碰撞冲击,提出一种自由漂浮空间机器人力-位-型融合控制方法。首先... 翻滚目标捕获过程中,空间机器人的运动会对基座产生扰动、接触过程的冲击碰撞容易产生安全风险。因此,为了在捕获翻滚目标的同时抑制空间机械臂对基座的扰动和对目标的碰撞冲击,提出一种自由漂浮空间机器人力-位-型融合控制方法。首先将自由漂浮空间机器人的非完整冗余性、运动冗余性表征为型空间,构建由末端位姿、型状态组合的广义状态空间并建立系统的运动学和动力学模型;通过优化基座与机械臂的位-型及零空间运动,减小机械臂抓捕运动在基座产生的扰动;通过优化基座、机械臂与翻滚目标的相对位-型,减小碰撞冲击力在基座产生的姿态扰动。给定最优位-型及末端操作力,基于阻抗控制原理及零空间投影策略,实现多优先级力-位-型融合控制。最后,开展了空间机器人捕获翻滚目标的典型任务仿真,结果表明通过力-位-型融合优化与控制方法可以有效减小空间机器人捕获过程产生的基座扰动。 展开更多
关键词 在轨捕获 翻滚目标 空间机器人 多目标优化 --型融合控制
下载PDF
Study on Logical Relations amongUnderground Survey Objects Using Quotient Topological Space 被引量:1
4
作者 陈宜金 《International Journal of Mining Science and Technology》 SCIE EI 1997年第2期7-10,共4页
A soitable data model and data structure make underground survey objects maintained and operated easier. This paper gives a formal definition for underground survey objects. By making use of the quotient topological s... A soitable data model and data structure make underground survey objects maintained and operated easier. This paper gives a formal definition for underground survey objects. By making use of the quotient topological space, the author studies the logical relations among underground survey objects, a partiallyordered space uuder some conditions. An example is given to show the data model’s possible applications. 展开更多
关键词 UNDERGROUND SURVEY objects QUOTIENT TOPOLOGICAL space logical RELATION
下载PDF
Spaceborne and ground-based sensor collaboration:Advancing resident space objects’orbit determination for space sustainability
5
作者 Niki Sajjad Mehran Mirshams Andreas Makoto Hein 《Astrodynamics》 EI CSCD 2024年第3期325-347,共23页
The limited space around the Earth is getting cluttered with leftover fragments from old missions,creating a real challenge.As more satellites are launched,even debris pieces as small as 5 mm must be tracked to avoid ... The limited space around the Earth is getting cluttered with leftover fragments from old missions,creating a real challenge.As more satellites are launched,even debris pieces as small as 5 mm must be tracked to avoid collisions.However,it is an arduous and challenging task in space.This paper presents a technical exploration of ground-based and in-orbit space debris tracking and orbit determination methods.It highlights the challenges faced during on-ground and in-orbit demonstrations,identifies current gaps,and proposes solutions following technological advancements,such as low-power pose estimation methods.Owing to the numerous atmospheric barriers to ground-based sensors,this study emphasizes the significance of spaceborne sensors for precise orbit determination,complemented by advanced data processing algorithms and collaborative efforts.The ultimate goal is to create a comprehensive catalog of resident space objects(RSO)around the Earth and promote space environment sustainability.By exploring different methods and finding innovative solutions,this study contributes to the protection of space for future exploration and the creation of a more transparent and precise map of orbital objects. 展开更多
关键词 resident space objects(RSO) space debris orbit determination tracking ground-based sensors spaceborne sensors
原文传递
协同生态系统服务与公平性的城市绿色空间配置优化----以武汉市中心城区为例
6
作者 谭传东 洪歌 吴雪飞 《现代城市研究》 北大核心 2024年第7期24-29,共6页
能提供多种生态系统服务的城市绿色空间对于改善城市环境、增进居民健康及福祉具有重要作用。在高密度城市建成环境中合理配置绿色空间,同时满足生态效益、社会公平及用地限制等多种目标,是实现城市可持续发展的重要途径之一。文章以武... 能提供多种生态系统服务的城市绿色空间对于改善城市环境、增进居民健康及福祉具有重要作用。在高密度城市建成环境中合理配置绿色空间,同时满足生态效益、社会公平及用地限制等多种目标,是实现城市可持续发展的重要途径之一。文章以武汉市中心城区为例,选择空气净化、热岛效应缓解和雨洪调节3项生态系统服务作为生态效益优化目标,使用绿色空间配置基尼系数表征公平性,基于多目标线性规划方法构建以生态系统服务最大化和公平性最大化为目标的城市绿色空间配置优化模型。研究结果表明:基于多目标线性规划的城市绿色空间配置优化模型能够综合考虑多种社会和环境制约因素,同时集成多种生态系统服务,以及权衡生态效益与公平性之间的矛盾。该模型具有足够的灵活性与扩展性,可为武汉以及其他城市区域的绿色空间配置优化提供新的方法与思路。 展开更多
关键词 城市绿色空间 生态系统服务 多目标优化 公平性 配置优化
下载PDF
基于Sentinel-2卫星影像的滨海筏式养殖区提取研究
7
作者 武义洲 胡德勇 《首都师范大学学报(自然科学版)》 2024年第5期11-18,共8页
我国滨海养殖在全球占有较大比例,快速获取滨海养殖区域大小和分布等信息,有利于实现对养殖区域的监测规划、产量估算和灾害预防。针对筏式养殖区提取过程中出现的与海水区分较困难、识别精度低和“椒盐”噪声等问题,本文将以长山群岛... 我国滨海养殖在全球占有较大比例,快速获取滨海养殖区域大小和分布等信息,有利于实现对养殖区域的监测规划、产量估算和灾害预防。针对筏式养殖区提取过程中出现的与海水区分较困难、识别精度低和“椒盐”噪声等问题,本文将以长山群岛附近筏式养殖区为研究区域,利用哨兵二号(Sentinel-2)卫星遥感影像数据构建光谱、纹理和几何等特征,通过特征域优化(FSO)获得提取筏式养殖区的优选特征,结合面向对象的随机森林、决策树和最近邻3种算法对研究区筏式养殖区进行提取,在分析和对比提取结果基础上,总结了最优分类算法,并验证了FSO分类的可靠性。结果表明:(1)归一化差分水体指数、几何特征边界和形状、灰度共生矩阵相关性是识别筏式养殖区的最优指标;(2)FSO分类保证了提取精度,减少了数据冗余、提高了运算效率,对筏式养殖的提取具有较高可靠性和适用性;(3)基于FSO和面向对象随机森林的分类方法综合评价最优,总体分类精度为88.8%,κ=0.801,该方法有效避免“椒盐”噪声的产生,可以高效精确的提取筏式养殖区专题信息。本研究可为筏式养殖的动态监测、产量估算等方面提供了技术和专题数据支持。 展开更多
关键词 Sentinel-2 筏式养殖区 面向对象 特征域优化
下载PDF
Observation of Complex Organic Molecules Containing Peptide-like Bonds Toward Hot Core G358.93-0.03 MM1
8
作者 Arijit Manna Sabyasachi Pal 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2024年第7期181-189,共9页
In star formation regions,the complex organic molecules(COMs)that contain peptide bonds(-NH-C(=O)-)play a major role in the metabolic process because-NH-C(=O)-is connected to amino acids(R-CHNH_2-COOH).Over the past f... In star formation regions,the complex organic molecules(COMs)that contain peptide bonds(-NH-C(=O)-)play a major role in the metabolic process because-NH-C(=O)-is connected to amino acids(R-CHNH_2-COOH).Over the past few decades,many COMs containing peptide-like bonds have been detected in hot molecular cores(HMCs),hot corinos,and cold molecular clouds,however,their prebiotic chemistry is poorly understood.We present the first detection of the rotational emission lines of formamide(NH_2CHO)and isocyanic acid(HNCO),which contain peptide-like bonds toward the chemically rich HMC G358.93-0.03 MM1,using high-resolution and high-sensitivity Atacama Large Millimeter/submillimeter Array bands 6 and 7.We estimate that the column densities of NH_2CHO and HNCO toward G358.93-0.03 MM1 are(2.80±0.29)×10~(15)cm~(-2)and(1.80±0.42)×10~(16)cm~(-2)with excitation temperatures of 165±21 K and 170±32 K,respectively.The fractional abundances of NH_2CHO and HNCO toward G358.93-0.03 MM1 are(9.03±1.44)×10~(-10)and(5.80±2.09)×10^(-9).We compare the estimated abundances of NH_2CHO and HNCO with the existing threephase warm-up chemical model abundance values and notice that the observed and modeled abundances are very close.We conclude that NH_2CHO is produced by the reaction of NH_2and H_2CO in the gas phase toward G358.93-0.03 MM1.Likewise,HNCO is produced on the surface of grains by the reaction of NH and CO toward G358.93-0.03 MM1.We also find that NH_2CHO and HNCO are chemically linked toward G358.93-0.03 MM1. 展开更多
关键词 ISM individual objects(G358.93-0.03)-ISM abundances-ISM kinematics and dynamics-stars formation-astrochemistry
下载PDF
Multi-objective Collaborative Optimization for Scheduling Aircraft Landing on Closely Spaced Parallel Runways Based on Genetic Algorithms 被引量:1
9
作者 Zhang Shuqin Jiang Yu Xia Hongshan 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI CSCD 2016年第4期502-509,共8页
A scheduling model of closely spaced parallel runways for arrival aircraft was proposed,with multi-objections of the minimum flight delay cost,the maximum airport capacity,the minimum workload of air traffic controlle... A scheduling model of closely spaced parallel runways for arrival aircraft was proposed,with multi-objections of the minimum flight delay cost,the maximum airport capacity,the minimum workload of air traffic controller and the maximum fairness of airlines′scheduling.The time interval between two runways and changes of aircraft landing order were taken as the constraints.Genetic algorithm was used to solve the model,and the model constrained unit delay cost of the aircraft with multiple flight tasks to reduce its delay influence range.Each objective function value or the fitness of particle unsatisfied the constrain condition would be punished.Finally,one domestic airport hub was introduced to verify the algorithm and the model.The results showed that the genetic algorithm presented strong convergence and timeliness for solving constraint multi-objective aircraft landing problem on closely spaced parallel runways,and the optimization results were better than that of actual scheduling. 展开更多
关键词 air transportation runway scheduling closely spaced parallel runways genetic algorithm multi-objections
下载PDF
Method for Collision Avoidance in Spacecraft Rendezvous Problems with Space Objects in a Phasing Orbit
10
作者 Danhe Chen A.A.Baranov +2 位作者 Chuangge Wang M.O.Karatunov N.Yu.Makarov 《Computer Modeling in Engineering & Sciences》 SCIE EI 2021年第6期977-991,共15页
As the number of space objects(SO)increases,collision avoidance problem in the rendezvous tasks or reconstellation of satellites with SO has been paid more attention,and the dangerous area of a possible collision shou... As the number of space objects(SO)increases,collision avoidance problem in the rendezvous tasks or reconstellation of satellites with SO has been paid more attention,and the dangerous area of a possible collision should be derived.In this paper,a maneuvering method is proposed for avoiding collision with a space debris object in the phasing orbit of the initial optimal solution.Accordingly,based on the plane of eccentricity vector components,relevant dangerous area which is bounded by two parallel lines is formulated.The axises of eccentricity vector system pass through the end of eccentricity vector of phasing orbit in the optimal solution,and orientation of axis depends on the latitude argument where a collision will occur.The dangerous area is represented especially with the graphical dialogue,and it allows to find a compromise between the SO avoiding and the fuel consumption reduction.The proposed method to solve the collision avoidance problem provides simplicity to calculate rendezvous maneuvers,and possibility to avoid collisions from several collisions or from“slow”collisions in a phasing orbit,when the protected spacecraft and the object fly dangerously close to each other for a long period. 展开更多
关键词 spaceCRAFT collision avoidance rendezvous problem space objects phasing orbit
下载PDF
Multi-Scale Object Perception with Embedding Textural Space
11
作者 Kewei Wu Zhao Xie Jun Gao 《International Journal of Intelligence Science》 2012年第2期32-39,共8页
This paper mainly focuses on the issues about generic multi-scale object perception for detection or recognition. A novel computational model in visually-feature space is presented for scene & object representatio... This paper mainly focuses on the issues about generic multi-scale object perception for detection or recognition. A novel computational model in visually-feature space is presented for scene & object representation to purse the underlying textural manifold statistically in nonparametric manner. The associative method approximately makes perceptual hierarchy in human-vision biologically coherency in specific quad-tree-pyramid structure, and the appropriate scale-value of different objects can automatically be selected by evaluating from well-defined scale function without any priori knowledge. The sufficient experiments truly demonstrate the effectiveness of scale determination in textural manifold with object localization rapidly. 展开更多
关键词 object PERCEPTION Scale space Textural MANIFOLD Quad-Tree Structure NONPARAMETRIC Estimation
下载PDF
Study of Complex Nitrogen and Oxygen-bearing Molecules toward the High-mass Protostar IRAS 18089–1732
12
作者 Arijit Manna Sabyasachi Pal +1 位作者 Tapas Baug Sougata Mondal 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2024年第6期81-93,共13页
The observation of oxygen(O)-and nitrogen(N)-bearing molecules gives an idea about the complex prebiotic chemistry in the interstellar medium.Recent millimeter and submillimeter wavelength observations have shown the ... The observation of oxygen(O)-and nitrogen(N)-bearing molecules gives an idea about the complex prebiotic chemistry in the interstellar medium.Recent millimeter and submillimeter wavelength observations have shown the presence of complex O-and N-bearing molecules in the star formation regions.So,the investigation of those molecules is crucial to understanding the chemical complexity in the star-forming regions.In this article,we present the identification of the rotational emission lines of N-bearing molecules ethyl cyanide(C_(2)H_(5)CN)and cyanoacetylene(HC_(3)N),and O-bearing molecule methyl formate(CH_(3)OCHO)toward high-mass protostar IRAS18089–1732 using the Atacama Compact Array.We also detected the emission lines of both the N-and O-bearing molecule formamide(NH_(2)CHO)in the envelope of IRAS 18089–1732.We have detected the v=0 and 1 state rotational emission lines of CH_(3)OCHO.We also detected the two vibrationally excited states of HC_(3)N(v7=1 and v7=2).The estimated fractional abundances of C_(2)H_(5)CN,HC_(3)N(v7=1),HC_(3)N(v7=2),and NH_(2)CHO toward IRAS 18089–1732 are(1.40±0.5)×10^(-10),(7.5±0.7)×10^(-11),(3.1±0.4)×10^(-11),and(6.25±0.82)×10^(-11)respectively.Similarly,the estimated fractional abundances of CH_(3)OCHO(v=0)and CH_(3)OCHO(v=1)are(1.90±0.9)×10^(-9)and(8.90±0.8)×10^(-10),respectively.We also created the integrated emission maps of the detected molecules,and the observed molecules may have originated from the extended envelope of the protostar.We show that C_(2)H_(5)CNand HC_(3)N are most probably formed via the subsequential hydrogenation of the CH_(2)CHCNand the reaction between C_(2)H_(2)and CN on the grain surface of IRAS 18089–1732.We found that NH_(2)CHO is probably produced due to the reaction between NH_(2)and H_(2)CO in the gas phase.Similarly,CH_(3)OCHO is possibly created via the reaction between radical CH_(3)O and radical HCO on the grain surface of IRAS 18089–1732. 展开更多
关键词 ISM:individual objects(IRA 18089-1732)(except) ISM:abundances ISM:kinematics and dynamics stars:formation ASTROCHEMISTRY
下载PDF
基于LSTM-Attention的空间目标分类研究
13
作者 杨礼友 余显冰 李智 《现代计算机》 2024年第6期38-43,共6页
针对空间目标特有属性及其运动趋势难以使用单一元素进行描述,以及现有空间目标分类技术准确度低等问题,构建了一种基于LSTM-Attention的空间目标分类模型,该模型无需开展额外的特征工程,能够联系空间目标序列数据的上下文信息和长期依... 针对空间目标特有属性及其运动趋势难以使用单一元素进行描述,以及现有空间目标分类技术准确度低等问题,构建了一种基于LSTM-Attention的空间目标分类模型,该模型无需开展额外的特征工程,能够联系空间目标序列数据的上下文信息和长期依赖关系,提取样本的局部特征并对其长期运动趋势进行建模。利用Mini-Mega TORTORA(MMT)系统实测光变曲线进行验证,与传统方法相比,设计使用的模型拥有较高的数据处理效率,能够提高空间目标的分类准确度并满足空间态势感知的部分应用需求。 展开更多
关键词 空间目标分类 深度学习 LSTM 注意力机制
下载PDF
基于NSGA-Ⅱ算法的阵元间距多目标优化
14
作者 陈师聪 章政 +1 位作者 黄卫华 杨继荣 《传感器与微系统》 CSCD 北大核心 2024年第4期128-131,共4页
针对定向扬声器换能器阵列设计的复杂性与不确定性问题,提出了一种基于NSGA-Ⅱ算法的矩形换能器阵元间距多目标优化方法。基于矩形换能器主要结构参数与阵元间距之间的动态性能分析,建立了以方向锐度角、主瓣波束宽度以及旁瓣级为协同... 针对定向扬声器换能器阵列设计的复杂性与不确定性问题,提出了一种基于NSGA-Ⅱ算法的矩形换能器阵元间距多目标优化方法。基于矩形换能器主要结构参数与阵元间距之间的动态性能分析,建立了以方向锐度角、主瓣波束宽度以及旁瓣级为协同优化目标的阵元间距解析函数和约束条件;在此基础上,采用NSGA-Ⅱ算法对所构建的多目标模型进行优化,由此获取矩形换能器阵元间距的最优可选集。仿真结果表明:在满足各项目标协同优化以及约束条件的情况下,所提出的矩形换能器阵元间距设计方法可实现换能器阵列旁瓣级较小且阵列指向性较好的定向扬声器。 展开更多
关键词 定向扬声器 矩形换能器阵列 阵元间距 多目标优化 NSGA-Ⅱ算法
下载PDF
Gamma-ray Emission from the γ-ray-loud BL Lac Objects
15
作者 Guang-ZhongXie Ben-ZhongDai +1 位作者 En-WeiLiang Zhao-HuaXie 《Chinese Journal of Astronomy and Astrophysics》 CSCD 北大核心 2001年第6期494-500,共7页
Using the HST observation data of BL Lac objects by Urry et al. and γ-ray observation data, we find that there is a correlation between Fγ and Fonuclei forγ-ray-loud BL Lac objects (correlation coefficients: 7γ=0.... Using the HST observation data of BL Lac objects by Urry et al. and γ-ray observation data, we find that there is a correlation between Fγ and Fonuclei forγ-ray-loud BL Lac objects (correlation coefficients: 7γ=0.63,p = 4.0 × 10-2), but no correlation between Fγ and Fohost, where Fonuclei and Fohost are the fluxes of nuclei and host galaxy in V-band. For 19γ-ray-loud BL Lac objects with observed spectral index in multi-wavebands, the spectral index correlations between any two bands are as follow: (1) there is a strong correlation between aγ and aK for 15 BL Lac objects(γ = 0.84,p = 3.11 × 10-4); (2) the correlation between aγ and ao for 12 BL Lac objects isγ = 0.82, p = 1.5 × 10-3; (3) there is no correlation between a7 and ax for 16 BL Lac objects. The results, together with characteristic double-humped shape of their SEDs, show that the synchrotron self-Compton mechanism might be a main mechanism for theγ-ray emission of the BL Lac objects. The electrons emitting JR and optical radiation via synchrotron are also responsible for upscattering these photons toγ-rays, and a variability in IR-optical regime should be accompanied by a change in theγ-rays. 展开更多
关键词 gamma rays - BL Lacertae objects: general
下载PDF
A Study of the Energy Sources of Herbig-Haro Objects
16
作者 Jing-Wen Yue-FangWu 《Chinese Journal of Astronomy and Astrophysics》 CSCD 北大核心 2002年第1期33-42,共10页
We make a statistical study of the energy sources of high-velocity phenomena, Herbig-Haro (HH) objects. IRAS counterparts of HH objects are identified. Their colors, brightness, geometric relation to the RH objects an... We make a statistical study of the energy sources of high-velocity phenomena, Herbig-Haro (HH) objects. IRAS counterparts of HH objects are identified. Their colors, brightness, geometric relation to the RH objects and SED are analysed. The sources are found to be concentrated in a band-shaped region in the IRAS color-color diagram. We suggest an explanation of thick surrounding material for this distribution. We propose a new method for identifying the energy sources based on color arid brightness. This method is applied to more than 200 HR objects whose energy sources are still unknown. Finally, a group of very young stellar object candidates which have similar properties to the RH energy sources is picked out. Their large-scale distribution is discussed. 展开更多
关键词 star: formation - ISM: Herbig-Haro objects - stars: pre-main- sequence
下载PDF
Multi-objective Evolutionary Algorithm Based on Target Space Partitioning Method
17
作者 尚兆霞 刘弘 李焱 《Journal of Donghua University(English Edition)》 EI CAS 2011年第2期177-181,共5页
Considering the defects of conventional optimization methods, a novel optimization algorithm is introduced in this paper. Target space partitioning method is used in this algorithm to solve multi-objective optimizatio... Considering the defects of conventional optimization methods, a novel optimization algorithm is introduced in this paper. Target space partitioning method is used in this algorithm to solve multi-objective optimization problem, thus achieve the coherent solution which can meet the requirements of all target functions, and improve the population's overall evolution level. The algorithm which guarantees diversity preservation and fast convergence to the Pareto set is applied to structural optimization problems. The empirical analysis supports the algorithm and gives an example with program. 展开更多
关键词 OPTIMIZATION ALGORITHM MULTI-objectIVE TARGET space partitioning METHOD
下载PDF
基于SPD-Conv结构和NAM注意力机制的鱼群小目标检测
18
作者 谌雨章 王诗琦 +1 位作者 周雯 周婉婷 《计算机科学》 CSCD 北大核心 2024年第S01期426-432,共7页
为解决因水下成像环境退化导致图像分辨率较低,以及因鱼群目标较小等因素导致的检测精度不高的问题,提出了一种结合SPD-Conv结构和NAM注意力机制的改进YOLOv7检测算法。首先,采用Space-to-Depth(SPD)结构改进头部网络,取代了网络中原有... 为解决因水下成像环境退化导致图像分辨率较低,以及因鱼群目标较小等因素导致的检测精度不高的问题,提出了一种结合SPD-Conv结构和NAM注意力机制的改进YOLOv7检测算法。首先,采用Space-to-Depth(SPD)结构改进头部网络,取代了网络中原有的跨步卷积结构,保留了更多的细粒度信息,提升了特征学习的效率,提高了网络对低分辨率图像的检测效果。然后在网络中引入Normalization-based Attention Module(NAM)注意力机制,采用CBAM的模块集成方式,使用BN缩放因子来计算注意力权重,抑制了不显著的特征,提升了小目标检测的准确率。最后针对水下成像退化,对检测图片做反卷积预处理,减小了水下成像退化因素对检测造成的影响。实验结果显示,在WildFish数据集上模型的整体精度达到97.2%,与YOLOv7算法相比提升了7.6%,准确率提升了8.5%,召回率提升了9.8%,与Efficientdet,SSD,YOLOv5及YOLOv8算法相比,所提模型精度分别提升了12.6%,17.8%,4%及2.9%,在Aquarium数据集上模型的整体精度达到80.5%,相比Efficientdet,SSD,YOLOv5,YOLOv7及YOLOv8分别提升了18.4%,11.6%,6.9%,2.0%及2.7%,可以满足水下鱼群识别的需求。 展开更多
关键词 SPD-Conv结构 NAM注意力机制 YOLOv7算法 鱼群检测 目标检测
下载PDF
基于TOPSIS-MOPSO的侦察星座优化设计
19
作者 刘亚丽 熊伟 +2 位作者 韩驰 熊明晖 刘正 《电讯技术》 北大核心 2024年第6期893-901,共9页
侦察星座优化是天基信息体系建设的关键问题。为弥补以往研究大多只采用少量性能指标进行侦察星座优化的不足,提出了一种综合考虑5项性能指标的侦察星座优化模型。在解算优化模型过程中,为解决传统基于Pareto支配的进化算法出现的选择... 侦察星座优化是天基信息体系建设的关键问题。为弥补以往研究大多只采用少量性能指标进行侦察星座优化的不足,提出了一种综合考虑5项性能指标的侦察星座优化模型。在解算优化模型过程中,为解决传统基于Pareto支配的进化算法出现的选择压力与多样性不足的问题,提出了TOPSIS-MOPSO(Technique for Order Preference by Similarity to an Ideal Solution-Multi-Objective Particle Swarm Optimization)算法,将多属性决策领域的TOPSIS引入进化算法中,并与SPD(Strengthened Pareto Dominate)相结合,得到一种能够同时增强种群收敛性与多样性的环境选择策略。提出了基于Harmonic距离的全局最优粒子选择策略,加快种群收敛速度,保护种群多样性;提出了自适应进化算子选择策略,帮助算法摆脱局部最优解。将TOPSIS-MOPSO算法应用在侦察星座优化问题上,并与MOPSO、DGEA、AR-MOEA 3种经典方法进行实验对比分析,实验结果显示,所提算法比其他3种算法在Δ*、IGD和HV上的最优指标值分别提升了19.76%、89.07%和28.2%。 展开更多
关键词 天基侦察系统 侦察星座优化 高维多目标优化 TOPSIS MOPSO
下载PDF
基于GF-1 PMS的喀斯特城镇绿地提取研究
20
作者 王玮 黄林 任金铜 《江苏科技信息》 2024年第12期137-140,共4页
绿地面积作为园林城市建设的重要指标,对于城市规划建设具有重要意义。文章基于面向对象分类算法,以位于喀斯特山区的贵州省毕节市海子街镇为研究区,利用高分一号(GF-1)PMS遥感影像进行城镇绿地提取。结果表明:绿地信息在GF-1 PMS影像... 绿地面积作为园林城市建设的重要指标,对于城市规划建设具有重要意义。文章基于面向对象分类算法,以位于喀斯特山区的贵州省毕节市海子街镇为研究区,利用高分一号(GF-1)PMS遥感影像进行城镇绿地提取。结果表明:绿地信息在GF-1 PMS影像上具有明显的光谱、纹理特征,通过对影像对象特征的不同选择和组合,能够很好地提取城镇绿地信息;在面向对象分类算法中,基于规则的绿地信息提取总体分类精度为79.36%,Kappa系数为0.76;基于样本的绿地信息提取总体分类精度为89.79%,Kappa系数为0.85,其提取效果比基于规则的面向对象方法更好。 展开更多
关键词 高分一号 城镇绿地 面向对象 信息提取
下载PDF
上一页 1 2 68 下一页 到第
使用帮助 返回顶部