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3D electrical resistivity inversion using prior spatial shape constraints 被引量:10
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作者 李术才 聂利超 +4 位作者 刘斌 宋杰 刘征宇 苏茂鑫 徐磊 《Applied Geophysics》 SCIE CSCD 2013年第4期361-372,510,共13页
To minimize the number of solutions in 3D resistivity inversion, an inherent problem in inversion, the amount of data considered have to be large and prior constraints need to be applied. Geological and geophysical da... To minimize the number of solutions in 3D resistivity inversion, an inherent problem in inversion, the amount of data considered have to be large and prior constraints need to be applied. Geological and geophysical data regarding the extent of a geological anomaly are important prior information. We propose the use of shape constraints in 3D electrical resistivity inversion, Three weighted orthogonal vectors (a normal and two tangent vectors) were used to control the resistivity differences at the boundaries of the anomaly. The spatial shape of the anomaly and the constraints on the boundaries of the anomaly are thus established. We incorporated the spatial shape constraints in the objective function of the 3D resistivity inversion and constructed the 3D resistivity inversion equation with spatial shape constraints. Subsequently, we used numerical modeling based on prior spatial shape data to constrain the direction vectors and weights of the 3D resistivity inversion. We established a reasonable range between the direction vectors and weights, and verified the feasibility and effectiveness of using spatial shape prior constraints in reducing excessive structures and the number of solutions. We applied the prior spatially shape-constrained inversion method to locate the aquifer at the Guangzhou subway. The spatial shape constraints were taken from ground penetrating radar data. The inversion results for the location and shape of the aquifer agree well with drilling data, and the number of inversion solutions is significantly reduced. 展开更多
关键词 electrical resistivity INVERSION prior spatial constraints direction vector GEOPHYSICS geotechnical engineering.
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Multichannel deconvolution based on spatial structurally constraint and its applications
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作者 Wang Wan-Li Jian Hu-Gao +1 位作者 Wang Wei Li Lin 《Applied Geophysics》 2025年第3期751-756,895,共7页
Traditional deconvolution methods based on single-channel inversion do not consider the spatial structural relation between channels,and hence,they yield high-resolution results with the existing transverse inconsiste... Traditional deconvolution methods based on single-channel inversion do not consider the spatial structural relation between channels,and hence,they yield high-resolution results with the existing transverse inconsistency or discontinuity.Therefore,in this study,the local dip angle was used to obtain the structural information and construct the spatial structurally constraint operator.This operator is then introduced into multichannel deconvolution as a regularization operator to improve the resolution and maintain the transverse continuity of seismic data.Model tests and actual seismic data processing have demonstrated the effectiveness and practicability of this method. 展开更多
关键词 transverse constraint spatial structurally constraint operator multichannel deconvolution
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Max-margin non-negative matrix factorization with flexible spatial constraints based on factor analysis
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作者 Dakun LIU Xiaoyang TAN 《Frontiers of Computer Science》 SCIE EI CSCD 2016年第2期302-316,共15页
Non-negative matrix factorization (NMF) is a popular feature encoding method for image understanding due to its non-negative properties in representation, but the learnt basis images are not always local due to the ... Non-negative matrix factorization (NMF) is a popular feature encoding method for image understanding due to its non-negative properties in representation, but the learnt basis images are not always local due to the lack of explicit constraints in its objective. Various algebraic or geometric local constraints are hence proposed to shape the behaviour of the original NMF. Such constraints are usually rigid in the sense that they have to be specified beforehand instead of learning from the data. In this paper, we propose a flexible spatial constraint method for NMF learning based on factor analysis. Particularly, to learn the local spatial structure of the images, we apply a series of transformations such as orthogonal rotation and thresholding to the factor loading matrix obtained through factor analysis. Then we map the transformed loading matrix into a Laplacian matrix and incorporate this into a max-margin non-negative matrix factorization framework as a penalty term, aiming to learn a representation space which is non-negative, discriminative and localstructure-preserving. We verify the feasibility and effectiveness of the proposed method on several real world datasets with encouraging results. 展开更多
关键词 non-negative matrix factorization factor analysis loading matrix flexible spatial constraints
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Global video object segmentation with spatial constraint module
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作者 Yadang Chen Duolin Wang +2 位作者 Zhiguo Chen Zhi-Xin Yang Enhua Wu 《Computational Visual Media》 SCIE EI CSCD 2023年第2期385-400,共16页
We present a lightweight and efficient semisupervised video object segmentation network based on the space-time memory framework.To some extent,our method solves the two difficulties encountered in traditional video o... We present a lightweight and efficient semisupervised video object segmentation network based on the space-time memory framework.To some extent,our method solves the two difficulties encountered in traditional video object segmentation:one is that the single frame calculation time is too long,and the other is that the current frame’s segmentation should use more information from past frames.The algorithm uses a global context(GC)module to achieve highperformance,real-time segmentation.The GC module can effectively integrate multi-frame image information without increased memory and can process each frame in real time.Moreover,the prediction mask of the previous frame is helpful for the segmentation of the current frame,so we input it into a spatial constraint module(SCM),which constrains the areas of segments in the current frame.The SCM effectively alleviates mismatching of similar targets yet consumes few additional resources.We added a refinement module to the decoder to improve boundary segmentation.Our model achieves state-of-the-art results on various datasets,scoring 80.1%on YouTube-VOS 2018 and a J&F score of 78.0%on DAVIS 2017,while taking 0.05 s per frame on the DAVIS 2016 validation dataset. 展开更多
关键词 video object segmentation semantic segmentation global context(GC)module spatial constraint
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Spatial geometric constraints histogram descriptors based on curvature mesh graph for 3D pollen particles recognition 被引量:1
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作者 谢永华 徐赵飞 Hans Burkhardt 《Chinese Physics B》 SCIE EI CAS CSCD 2014年第6期123-130,共8页
This paper presents one novel spatial geometric constraints histogram descriptors (SGCHD) based on curvature mesh graph for automatic three-dimensional (3D) pollen particles recognition. In order to reduce high di... This paper presents one novel spatial geometric constraints histogram descriptors (SGCHD) based on curvature mesh graph for automatic three-dimensional (3D) pollen particles recognition. In order to reduce high dimensionality and noise disturbance arising from the abnormal record approach under microscopy, the separated surface curvature voxels are ex- tracted as primitive features to represent the original 3D pollen particles, which can also greatly reduce the computation time for later feature extraction process. Due to the good invariance to pollen rotation and scaling transformation, the spatial geometric constraints vectors are calculated to describe the spatial position correlations of the curvature voxels on the 3D curvature mesh graph. For exact similarity evaluation purpose, the bidirectional histogram algorithm is applied to the spatial geometric constraints vectors to obtain the statistical histogram descriptors with fixed dimensionality, which is invariant to the number and the starting position of the curvature voxels. Our experimental results compared with the traditional methods validate the argument that the presented descriptors are invariant to different pollen particles geometric transformations (such as posing change and spatial rotation), and high recognition precision and speed can be obtained simultaneously. 展开更多
关键词 pollen recognition curvature mesh graph spatial geometric constraints bidirectional histogram
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Flight parameter calculation method of multi-projectiles using temporal and spatial information constraint 被引量:1
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作者 Han-shan Li Xiao-qian Zhang 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2023年第1期63-75,共13页
The dynamic parameters of multiple projectiles that are fired using multi-barrel weapons in highfrequency continuous firing modes are important indicators to measure the performance of these weapons.The characteristic... The dynamic parameters of multiple projectiles that are fired using multi-barrel weapons in highfrequency continuous firing modes are important indicators to measure the performance of these weapons.The characteristics of multiple projectiles are high randomness and large numbers launched in a short period of time,making it very difficult to obtain the real dispersion parameters of the projectiles due to the occlusion or coincidence of multiple projectiles.Using six intersecting-screen testing system,in this paper,we propose an association recognition and matching algorithm of multiple projectiles using a temporal and spatial information constraint mechanism.We extract the output signal from each detection screen and then use the wavelet transform to process the output signal.We present a method to identify and extract the time values on which the projectiles pass through the detection screens using the wavelet transform modulus maximum theory.We then use the correlation of the output signals of three parallel detection screens to establish a correlation coefficient recognition constraint function for the multiple projectiles.Based on the premise of linear projectile motion,we establish a temporal and spatial constraint matching model using the projectile’s position coordinates in each detection screen and the projectile’s time constraints within the multiple intersecting-screen geometry.We then determine the time values of the multiple projectiles in each detection screen using an iterative search cycle registration,and finally obtain the flight parameters for the multiple projectiles in the presence of uncertainty.The proposed method and algorithm were verified experimentally and can solve the problem of uncertainty in projectiles flight parameter under different multiple projectile firing states. 展开更多
关键词 Six detection screen array Multi-projectile Recognition and matching Temporal and spatial information constraint Wavelet transform
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Over-Constraints and a Unified Mobility Method for General Spatial Mechanisms Part 2:Application of the Principle 被引量:4
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作者 LU Wenjuan ZENG Daxing HUANG Zhen 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2016年第1期1-10,共10页
The pre-research on mobility analysis presented a unified-mobility formula and a methodology based on reciprocal screw theory by HUANG, which focused on classical and modem parallel mechanisms. However its range of ap... The pre-research on mobility analysis presented a unified-mobility formula and a methodology based on reciprocal screw theory by HUANG, which focused on classical and modem parallel mechanisms. However its range of application needs to further extend to general multi-loop spatial mechanism. This kind of mechanism is not only more complex in structure but also with strong motion coupling among loops, making the mobility analysis even more complicated, and the relevant research has long been ignored. It is focused on how to apply the new principle for general spatial mechanism to those various multi-loop spatial mechanisms, and some new meaningful knowledge is further found. Several typical examples of the genera/multi-loop spatial mechanisms with motion couple even strong motion couple are considered. These spatial mechanisms include different closing way: over-constraint appearing in rigid closure, in movable closure, and in dynamic closure as well; these examples also include two different new methods to solve this kind of issue: the way to recognize over-constraints by analyzing relative movement between two connected links and by constructing a virtual loop to recognize over-constraints. In addition, over-constraint determination tabulation is brought to analyze the motion couple. The researches above are all based upon the screw theory. All these multi-loop spatial mechanisms with different kinds of structures can completely be solved by following the directions and examples, and the new mobility theory based on the screw theory is also proved to be valid. This study not only enriches and develops the theory and makes the theory more universal, but also has a special meaning for innovation in mechanical engineering. 展开更多
关键词 mobility analysis over-constraint multi-loop spatial mechanism motion coupling screw theory
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Unknown DDoS Attack Detection with Fuzzy C-Means Clustering and Spatial Location Constraint Prototype Loss
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作者 Thanh-Lam Nguyen HaoKao +2 位作者 Thanh-Tuan Nguyen Mong-Fong Horng Chin-Shiuh Shieh 《Computers, Materials & Continua》 SCIE EI 2024年第2期2181-2205,共25页
Since its inception,the Internet has been rapidly evolving.With the advancement of science and technology and the explosive growth of the population,the demand for the Internet has been on the rise.Many applications i... Since its inception,the Internet has been rapidly evolving.With the advancement of science and technology and the explosive growth of the population,the demand for the Internet has been on the rise.Many applications in education,healthcare,entertainment,science,and more are being increasingly deployed based on the internet.Concurrently,malicious threats on the internet are on the rise as well.Distributed Denial of Service(DDoS)attacks are among the most common and dangerous threats on the internet today.The scale and complexity of DDoS attacks are constantly growing.Intrusion Detection Systems(IDS)have been deployed and have demonstrated their effectiveness in defense against those threats.In addition,the research of Machine Learning(ML)and Deep Learning(DL)in IDS has gained effective results and significant attention.However,one of the challenges when applying ML and DL techniques in intrusion detection is the identification of unknown attacks.These attacks,which are not encountered during the system’s training,can lead to misclassification with significant errors.In this research,we focused on addressing the issue of Unknown Attack Detection,combining two methods:Spatial Location Constraint Prototype Loss(SLCPL)and Fuzzy C-Means(FCM).With the proposed method,we achieved promising results compared to traditional methods.The proposed method demonstrates a very high accuracy of up to 99.8%with a low false positive rate for known attacks on the Intrusion Detection Evaluation Dataset(CICIDS2017)dataset.Particularly,the accuracy is also very high,reaching 99.7%,and the precision goes up to 99.9%for unknown DDoS attacks on the DDoS Evaluation Dataset(CICDDoS2019)dataset.The success of the proposed method is due to the combination of SLCPL,an advanced Open-Set Recognition(OSR)technique,and FCM,a traditional yet highly applicable clustering technique.This has yielded a novel method in the field of unknown attack detection.This further expands the trend of applying DL and ML techniques in the development of intrusion detection systems and cybersecurity.Finally,implementing the proposed method in real-world systems can enhance the security capabilities against increasingly complex threats on computer networks. 展开更多
关键词 CYBERSECURITY DDoS unknown attack detection machine learning deep learning incremental learning convolutional neural networks(CNN) open-set recognition(OSR) spatial location constraint prototype loss fuzzy c-means CICIDS2017 CICDDoS2019
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FRAMEWORKS FOR GENERALIZATION CONSTRAINTS AND OPERATIONS BASED ON OBJECT-ORIENTED DATA STRUCTURE IN DATABASE GENERALIZATION 被引量:1
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作者 LIU Yaolin Martien Molenaar AI Tinghua LIU Yanfang 《Geo-Spatial Information Science》 2001年第3期42-49,共8页
The constraints and the operations play an important role in database generalization.They guide and govern database generalization.The constraints are translation of the required conditions that should take into accou... The constraints and the operations play an important role in database generalization.They guide and govern database generalization.The constraints are translation of the required conditions that should take into account not only the objects and relationships among objects but also spatial data schema (classification and aggregation hierarchy) associated with the final existing database.The operations perform the actions of generalization in support of data reduction in the database.The constraints in database generalization are still lack of research.There is still the lack of frameworks to express the constraints and the operations on the basis of object_oriented data structure in database generalization.This paper focuses on the frameworks for generalization operations and constraints on the basis of object_oriented data structure in database generalization.The constraints as the attributes of the object and the operations as the methods of the object can be encapsulated in classes.They have the inheritance and polymorphism property.So the framework of the constraints and the operations which are based on object_oriented data structure can be easily understood and implemented.The constraint and the operations based on object_oriented database are proposed based on object_oriented database.The frameworks for generalization operations,constraints and relations among objects based on object_oriented data structure in database generalization are designed.The categorical database generalization is concentrated on in this paper. 展开更多
关键词 constraintS database generalization operation spatial object HIERARCHY
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Preprocessing of Spatial Query in Distributed GIS
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作者 Shengsheng Wang Dayou Liu Jie Liu 《通讯和计算机(中英文版)》 2005年第5期1-5,共5页
关键词 地理信息系统 数据处理 操作系统 信息共享
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生态安全约束下环鄱阳湖城市群产业投资空间关联网络与驱动因素研究 被引量:1
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作者 刘耀彬 王梓畅 +1 位作者 骆康 胡伟辉 《长江流域资源与环境》 北大核心 2025年第8期1677-1692,共16页
流空间背景下企业异地投资为城市网络发展注入强大动力,生态安全影响着产业投资网络的形成和结构。环鄱阳湖城市群是人地矛盾敏感地带,自然生态底色具有湖域独特性。以环鄱阳湖城市群为研究区域,运用生态安全约束下城市群流空间的研究框... 流空间背景下企业异地投资为城市网络发展注入强大动力,生态安全影响着产业投资网络的形成和结构。环鄱阳湖城市群是人地矛盾敏感地带,自然生态底色具有湖域独特性。以环鄱阳湖城市群为研究区域,运用生态安全约束下城市群流空间的研究框架,采用修正引力模型刻画其产业投资流关联强度,运用社会网络分析法探讨其生态安全约束下产业投资的空间关联网络特征及驱动因素。研究发现:(1)生态安全约束下环鄱阳湖城市群产业投资空间网络具有明显的“中心—外围”特征,且产业投资流的空间联系在不断加强,网络结构愈发稳定;(2)少数经济较发达地区长期占据网络的中心位置,同时扮演高效的中介角色,网络外围地区存在发展路径突破现象;(3)生态安全约束下环鄱阳湖城市群产业投资空间关联网络的板块特征存在较强的空间依赖性,同一板块的城市在地理位置上呈现抱团取暖特征;(4)对外开放水平、政府调控、人口城镇化水平和土地城镇化水平的相近性对生态安全约束下环鄱阳湖城市群产业投资的空间网络具有显著正向影响。 展开更多
关键词 产业投资流 空间关联网络 生态安全约束 驱动因素 社会网络分析 环鄱阳湖城市群
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约束条件和异方差下部分线性空间自回归模型的统计推断
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作者 李体政 谭允迪 程瑶瑶 《工程数学学报》 北大核心 2025年第6期1029-1046,共18页
在回归分析的许多应用中,回归系数往往满足约束条件并且误差项不满足等方差假定,在约束条件和异方差下研究部分线性空间自回归模型的统计推断问题,基于局部多项式光滑方法、广义矩方法以及拉格朗日乘子方法,构建了模型参数和未知函数的... 在回归分析的许多应用中,回归系数往往满足约束条件并且误差项不满足等方差假定,在约束条件和异方差下研究部分线性空间自回归模型的统计推断问题,基于局部多项式光滑方法、广义矩方法以及拉格朗日乘子方法,构建了模型参数和未知函数的约束估计,并在适当的正则条件下研究了所得估计的渐近性质。进一步,构造了一个Wald型统计量检验回归系数是否满足线性约束条件,并在零假设和备择假设下证明了检验统计量都渐近服从卡方分布。模拟研究和实例分析展示了所提出的估计和检验方法在有限样本时的表现。 展开更多
关键词 空间相关 部分线性空间自回归模型 约束条件 异方差 工具变量
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基于分层解析的水资源空间均衡量化与调控 被引量:1
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作者 游进军 马真臻 +3 位作者 蒋云钟 王婷 王慧宁 李宁博 《中国水利》 2025年第17期35-40,共6页
“空间均衡”是新时期立足国情水情、统筹水安全与高质量发展的核心战略目标。尽管当前已形成“水与发展、保护需协调适配”的空间均衡理念共识,但在多维协调关系解析、空间均衡相对性动态性、可利用水资源范围与边界、水源开发强度均... “空间均衡”是新时期立足国情水情、统筹水安全与高质量发展的核心战略目标。尽管当前已形成“水与发展、保护需协调适配”的空间均衡理念共识,但在多维协调关系解析、空间均衡相对性动态性、可利用水资源范围与边界、水源开发强度均衡性等认知和方法上仍有局限,导致空间均衡理念难以落到实处,未能有效转化为治水动能。紧扣国家水网和水资源刚性约束制度建设需求,构建“认知-诊断-调控”的空间均衡分层解析路径。认知层面,基于适水发展理念提出“多维协调、分布均衡”的空间均衡内涵,前者突出水-经济-生态多系统交互协调性,后者关注空间上的合理分布与均衡匹配;诊断层面,前置保护要求,从水与发展、水源开发两方面构建可量化评估的指标体系,提出“全域-单元”联动的识别方法,建立从宏观多维协调关系到微观状态分布均衡的量化表达,识别问题和调控需求;调控层面,基于诊断结果明晰调控方向,提出保护、发展与开发协同调控的对策措施。方法可为科学判别水资源空间均衡状态、精准实施水资源调配提供决策支撑,丰富高质量发展下的水安全保障实践路径。 展开更多
关键词 空间均衡 水资源刚性约束 四水四定 协同调控 水资源调配
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新时期水资源调配的关键问题与实施路径 被引量:3
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作者 王浩 游进军 +2 位作者 王婷 蒋云钟 李君宇 《中国水利》 2025年第13期8-13,共6页
水资源调配是实现水资源空间均衡、发挥水网整体效能、促进高质量发展的关键措施。当前,水资源刚性约束制度和国家水网建设作为重大战略正在同步推进实施,“四水四定”“适水发展”理念正逐步成为社会共识并落实到行业管理中,水资源调... 水资源调配是实现水资源空间均衡、发挥水网整体效能、促进高质量发展的关键措施。当前,水资源刚性约束制度和国家水网建设作为重大战略正在同步推进实施,“四水四定”“适水发展”理念正逐步成为社会共识并落实到行业管理中,水资源调配要求和条件发生了根本性变革,新时期技术方法的进步也带来了新的机遇。传统“以水论水”“以需定供”模式的水资源调配已经不能适应新形势、新要求,需要提高认识、把准问题并抓住机遇,提出有效解决方案。在分析新时期水资源调配面临的机遇和挑战基础上,提出了当前在调配范围和决策方向、调配路径分析、供需形势判断、调配措施制定等方面面临的关键问题,按照切实遵循水资源刚性约束、坚持“空间均衡”、落实“以水定需”调配原则,分析了解决的方案和应对措施。针对存在问题,从政策导向、技术突破、工具研发、标准制定等方面,提出了推动水资源调配管理现代化的实施路径,相关成果可为区域行业发展规划、水利工程优化布局、涉水管理政策制定等提供借鉴参考。 展开更多
关键词 水资源调配 水资源刚性约束 供需分析 空间均衡 四水四定 国家水网
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结合配准补偿和空间约束的隧道三维建图方法
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作者 张星 黄展鹏 +2 位作者 李清泉 周宝定 李麒沛 《测绘学报》 北大核心 2025年第2期297-307,共11页
三维地图对于隧道的施工安全预警和长期安全维护至关重要。然而,在纹理缺乏、结构粗糙且存在动态干扰的隧道环境中,生成准确的三维点云地图是一项具有挑战性的任务。本文提出了一种隧道三维建图方法,用于构建超长且高噪声隧道场景的点... 三维地图对于隧道的施工安全预警和长期安全维护至关重要。然而,在纹理缺乏、结构粗糙且存在动态干扰的隧道环境中,生成准确的三维点云地图是一项具有挑战性的任务。本文提出了一种隧道三维建图方法,用于构建超长且高噪声隧道场景的点云地图。首先,提出了一种配准残差补偿模型,以减少由粗糙表面结构引起的配准误差。该模型利用K均值聚类算法识别非平整表面结构,并通过局部区域残差进行有效补偿。然后,提出了一种基于视场最大化的空间约束模型,以排除绝对测量偏差造成的点云误差。为了验证本方法的性能,本文在钻爆法和盾构法隧道的二次衬砌和管沟敷设阶段进行了试验。结果表明,该方法较主流建图算法FAST-LIO2、Faster-LIO和LiLi-OM具有更准确的轨迹估计和地图构建。此外,本文进行了一些消融试验,以进一步阐明不同模型在隧道三维建图中的作用。 展开更多
关键词 建图 配准补偿 空间约束 激光雷达 四足机器人
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空间约束中药材等离子体最佳探测时间研究
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作者 陶翰飞 赵静怡 +3 位作者 王浪 李业秋 崔建丰 岱钦 《激光杂志》 北大核心 2025年第3期91-97,共7页
利用激光诱导击穿光谱技术和空间约束方法对不同元素特征谱线的最佳探测延迟时间进行研究,建立等离子体热膨胀模型,模拟等离子体在不同空间约束深度和时间的热膨胀瞬态过程,分析了环境气压、温度和湿度的变化对结果的影响。对不同空间... 利用激光诱导击穿光谱技术和空间约束方法对不同元素特征谱线的最佳探测延迟时间进行研究,建立等离子体热膨胀模型,模拟等离子体在不同空间约束深度和时间的热膨胀瞬态过程,分析了环境气压、温度和湿度的变化对结果的影响。对不同空间约束深度的中药材玉竹样品进行激光诱导击穿光谱检测实验,以MgⅠ285.12 nm和CaⅡ396.84 nm作为特征分析谱线,分析了空间约束深度和时间的变化对谱线强度的影响,并探究了激发光源输出特性的变化对谱线强度的影响。在激光能量为30 mJ,重复频率为1 Hz,最佳空间约束深度为1.9 mm的条件下谱线强度得到明显加强,Mg元素的最佳探测时间为0.5μs,而Ca元素的最佳探测时间为1.2μs,表明不同元素在相同空间约束深度下对谱线增强效果最佳的探测时间不同。 展开更多
关键词 激光诱导击穿光谱 空间约束 时间分辨 最佳探测时间
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地理链接数据的空间拓扑完整性验证
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作者 卢禹博 叶育鑫 欧阳丹彤 《吉林大学学报(理学版)》 北大核心 2025年第1期60-66,共7页
为能准确且快捷地验证地理链接数据多重实体空间拓扑关系的完整性,提出一种基于RCC8模型的饱和推理方法,用于检验多重空间拓扑关系是否具有冲突.该方法应用推理规则,将关系对进行两两组合推理,逐步推导出潜在空间关系并对推理结果进行检... 为能准确且快捷地验证地理链接数据多重实体空间拓扑关系的完整性,提出一种基于RCC8模型的饱和推理方法,用于检验多重空间拓扑关系是否具有冲突.该方法应用推理规则,将关系对进行两两组合推理,逐步推导出潜在空间关系并对推理结果进行检验,不断重复以上过程,直到确保推理过程在所有关系对均被推导后终止.在此基础上,封装一个基于RCC8模型的饱和推理验证组件,以方便使用者在无需重复编写代码的情况下,通过直接调用组件验证多重空间拓扑关系.利用该方法和组件对SLIPO项目的链接数据集的部分数据进行测试,成功识别出GeoSHACL组件无法检测到的多个空间拓扑关系冲突实体. 展开更多
关键词 地理链接数据 空间完整性约束 饱和式推理 完整性验证 空间约束组件
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基于空间约束的差动共焦离轴非球面自适应测量方法
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作者 马维阔 邱丽荣 +2 位作者 李奕豪 赵维谦 刘昱含 《光学精密工程》 北大核心 2025年第12期1831-1841,共11页
离轴非球面形状不对称且其表面曲率变化非线性,给面形高精度测量带来挑战。为解决现有离轴非球面面形测量方法高度依赖待测件初始调整位姿和曲率变化难适应的问题,本文提出了一种基于空间约束的差动共焦离轴非球面自适应测量方法,以实... 离轴非球面形状不对称且其表面曲率变化非线性,给面形高精度测量带来挑战。为解决现有离轴非球面面形测量方法高度依赖待测件初始调整位姿和曲率变化难适应的问题,本文提出了一种基于空间约束的差动共焦离轴非球面自适应测量方法,以实现对离轴非球面的无初始位姿依赖、曲率变化自适应、高精度测量。首先,根据平移-回转扫描测量原理和差动共焦技术抗表面倾角精准定焦的性能,从规划测量点和待测点之间的距离和倾角两个维度出发,构建了空间约束模型,基于该模型,对等面积准则下的螺旋扫描路径规划算法进行优化,实现对离轴非球面测量路径的曲率自适应动态调整。使用该方法对离轴非球面和20°倾斜平面进行测量实验,将测量结果与Zygo干涉仪的测量结果点对点作差,面形差别的均方根(Root Mean Square,RMS)值均优于10 nm,对应3σ优于5 nm,满足离轴非球面的高精度测量要求。 展开更多
关键词 空间约束 差动共焦 离轴非球面 自适应测量 路径规划
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攻击角度和时间精确控制的制导律设计 被引量:1
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作者 董伟 易鑫 +2 位作者 张后军 王春彦 邓方 《航空学报》 北大核心 2025年第4期200-216,共17页
时空约束制导是指同时满足攻击角度和攻击时间约束的制导方式。针对导弹末制导问题,设计了一种具有精确控制能力的时空约束制导律。首先,基于最优落角约束制导律的剩余飞行时间估计式,在不依赖于小角度假设的情况下,逆向推导了剩余飞行... 时空约束制导是指同时满足攻击角度和攻击时间约束的制导方式。针对导弹末制导问题,设计了一种具有精确控制能力的时空约束制导律。首先,基于最优落角约束制导律的剩余飞行时间估计式,在不依赖于小角度假设的情况下,逆向推导了剩余飞行时间可以精确预测的变增益落角约束制导律。其次,在该制导律的基础上增加攻击时间误差反馈项,设计得到了不存在指令奇异现象的时空约束制导律,实现了攻击角度和时间的同时精确控制。接着,引入剩余弹道长度作为自变量,将所提出的时空约束制导律拓展到了导弹速度大小变化的实际场景。最后,通过多组数值仿真算例,验证了所提制导律的有效性和优势。 展开更多
关键词 攻击时间约束 攻击角度约束 时空约束制导 剩余飞行时间 导弹速度变化
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小农经济现代化发展的空间束缚及其叠层性支配形塑 被引量:1
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作者 雷贵 《农林经济管理学报》 北大核心 2025年第2期235-243,共9页
基于空间角度,以粤东林村为例,探讨小农经济现代化发展所面临的空间束缚及形塑的结构性因素。结果表明:小农户依托空间的地理资源禀赋,通过示范性动员扩散与社会性嵌入发展策略,推动小农经济现代化进程。在小农经济现代化发展过程中,小... 基于空间角度,以粤东林村为例,探讨小农经济现代化发展所面临的空间束缚及形塑的结构性因素。结果表明:小农户依托空间的地理资源禀赋,通过示范性动员扩散与社会性嵌入发展策略,推动小农经济现代化进程。在小农经济现代化发展过程中,小农户面临结构性空间束缚,主要表现为空间资源供给不足、空间设施建设滞后及空间发展区域锁定等问题。空间束缚是多方力量对村域空间的叠层性支配结构形塑的结果,多元主体基于自身发展意图和利益关系,以地理底层制约、社会惯习牵制、资本占有挤压和政策刚性规制等形式共同支配村域空间,并在既有空间不断叠层累加,形成具有约束性的复合空间结构,进而束缚小农经济现代化的持续发展。据此,建议进一步关注小农经济现代化发展的空间维度实践及其存在困境,完善相关空间设施建设,打破结构性空间束缚,为小农户营造更加有利的发展环境。 展开更多
关键词 小农户 小农经济 现代化发展 空间束缚 叠层性支配
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