期刊文献+
共找到189篇文章
< 1 2 10 >
每页显示 20 50 100
Source localization in signed networks with effective distance
1
作者 马志伟 孙蕾 +2 位作者 丁智国 黄宜真 胡兆龙 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第2期577-585,共9页
While progress has been made in information source localization,it has overlooked the prevalent friend and adversarial relationships in social networks.This paper addresses this gap by focusing on source localization ... While progress has been made in information source localization,it has overlooked the prevalent friend and adversarial relationships in social networks.This paper addresses this gap by focusing on source localization in signed network models.Leveraging the topological characteristics of signed networks and transforming the propagation probability into effective distance,we propose an optimization method for observer selection.Additionally,by using the reverse propagation algorithm we present a method for information source localization in signed networks.Extensive experimental results demonstrate that a higher proportion of positive edges within signed networks contributes to more favorable source localization,and the higher the ratio of propagation rates between positive and negative edges,the more accurate the source localization becomes.Interestingly,this aligns with our observation that,in reality,the number of friends tends to be greater than the number of adversaries,and the likelihood of information propagation among friends is often higher than among adversaries.In addition,the source located at the periphery of the network is not easy to identify.Furthermore,our proposed observer selection method based on effective distance achieves higher operational efficiency and exhibits higher accuracy in information source localization,compared with three strategies for observer selection based on the classical full-order neighbor coverage. 展开更多
关键词 complex networks signed networks source localization effective distance
下载PDF
Placement distance of freeway exit advance guide sign and its safety impacts 被引量:3
2
作者 郭唐仪 邓卫 +1 位作者 侯建生 Lu John 《Journal of Southeast University(English Edition)》 EI CAS 2010年第4期622-627,共6页
To remedy the empirical pitfalls of current chinese specifications and MUTCD 2009 guidelines in determining the placement distance of freeway exit advance guide signs,the driving maneuver of exiting traffic is analyze... To remedy the empirical pitfalls of current chinese specifications and MUTCD 2009 guidelines in determining the placement distance of freeway exit advance guide signs,the driving maneuver of exiting traffic is analyzed and the factors influencing placement distance are explored.Variables including the number of lanes,lane width,lane-changing time,driver's visual characteristics,sign installation methods and operating speeds on both freeway mainlines and exit ramps are found significant in explaining exit safety.Three different installation methods,namely ground installation,overhead installation and median installation,are introduced and their applicable conditions are given.Models,with the same structure among the three installation methods,are developed to compute the placement distance under different roadway geometric and traffic conditions.Taking overhead installation as an example,simulation results in TSIS-CORSIM show that the proposed distance reduces the number of lane changes in the area from the ramp nose to 500 m upstream by 58.93% compared with current Chinese specifications and 27.35% compared with MUTCD 2009 guidelines.Thus,the distances recommended in this paper have a better safety performance. 展开更多
关键词 FREEWAY advance guide sign placement distance safety impact lane change
下载PDF
Japanese Sign Language Recognition by Combining Joint Skeleton-Based Handcrafted and Pixel-Based Deep Learning Features with Machine Learning Classification
3
作者 Jungpil Shin Md.Al Mehedi Hasan +2 位作者 Abu Saleh Musa Miah Kota Suzuki Koki Hirooka 《Computer Modeling in Engineering & Sciences》 SCIE EI 2024年第6期2605-2625,共21页
Sign language recognition is vital for enhancing communication accessibility among the Deaf and hard-of-hearing communities.In Japan,approximately 360,000 individualswith hearing and speech disabilities rely on Japane... Sign language recognition is vital for enhancing communication accessibility among the Deaf and hard-of-hearing communities.In Japan,approximately 360,000 individualswith hearing and speech disabilities rely on Japanese Sign Language(JSL)for communication.However,existing JSL recognition systems have faced significant performance limitations due to inherent complexities.In response to these challenges,we present a novel JSL recognition system that employs a strategic fusion approach,combining joint skeleton-based handcrafted features and pixel-based deep learning features.Our system incorporates two distinct streams:the first stream extracts crucial handcrafted features,emphasizing the capture of hand and body movements within JSL gestures.Simultaneously,a deep learning-based transfer learning stream captures hierarchical representations of JSL gestures in the second stream.Then,we concatenated the critical information of the first stream and the hierarchy of the second stream features to produce the multiple levels of the fusion features,aiming to create a comprehensive representation of the JSL gestures.After reducing the dimensionality of the feature,a feature selection approach and a kernel-based support vector machine(SVM)were used for the classification.To assess the effectiveness of our approach,we conducted extensive experiments on our Lab JSL dataset and a publicly available Arabic sign language(ArSL)dataset.Our results unequivocally demonstrate that our fusion approach significantly enhances JSL recognition accuracy and robustness compared to individual feature sets or traditional recognition methods. 展开更多
关键词 Japanese sign Language(JSL) hand gesture recognition geometric feature distance feature angle feature GoogleNet
下载PDF
Intelligent Dynamic Gesture Recognition Using CNN Empowered by Edit Distance 被引量:1
4
作者 Shazia Saqib Allah Ditta +2 位作者 Muhammad Adnan Khan Syed Asad Raza Kazmi Hani Alquhayz 《Computers, Materials & Continua》 SCIE EI 2021年第2期2061-2076,共16页
Human activity detection and recognition is a challenging task.Video surveillance can benefit greatly by advances in Internet of Things(IoT)and cloud computing.Artificial intelligence IoT(AIoT)based devices form the b... Human activity detection and recognition is a challenging task.Video surveillance can benefit greatly by advances in Internet of Things(IoT)and cloud computing.Artificial intelligence IoT(AIoT)based devices form the basis of a smart city.The research presents Intelligent dynamic gesture recognition(IDGR)using a Convolutional neural network(CNN)empowered by edit distance for video recognition.The proposed system has been evaluated using AIoT enabled devices for static and dynamic gestures of Pakistani sign language(PSL).However,the proposed methodology can work efficiently for any type of video.The proposed research concludes that deep learning and convolutional neural networks give a most appropriate solution retaining discriminative and dynamic information of the input action.The research proposes recognition of dynamic gestures using image recognition of the keyframes based on CNN extracted from the human activity.Edit distance is used to find out the label of the word to which those sets of frames belong to.The simulation results have shown that at 400 videos per human action,100 epochs,234×234 image size,the accuracy of the system is 90.79%,which is a reasonable accuracy for a relatively small dataset as compared to the previously published techniques. 展开更多
关键词 sign languages keyframe edit distance misrate ACCURACY
下载PDF
Interval-Valued Intuitionistic Fuzzy-Rough Sets
5
作者 WU Yan-hua LI Ke-dian 《浙江海洋学院学报(自然科学版)》 CAS 2010年第5期496-506,共11页
This paper combines interval-valued intuitionistic fuzzy sets and rough sets.It studies rougheness in interval-valued intuitionistic fuzzy sets and proposes one kind of interval-valued intuitionistic fuzzy-rough sets ... This paper combines interval-valued intuitionistic fuzzy sets and rough sets.It studies rougheness in interval-valued intuitionistic fuzzy sets and proposes one kind of interval-valued intuitionistic fuzzy-rough sets models under the equivalence relation in crisp sets.That extends the classical rough set defined by Pawlak. 展开更多
关键词 interval-valued intuitionistic fuzzy sets interval-valued intuitionistic fuzzy rough sets Hamming distance Approximation roughness
下载PDF
SDF-Based ILW:Inverse Lax-Wendroff Method with the Signed Distance Function Representation of the Geometric Boundary
6
作者 Cheng Peng Shihao Liu Zhouwang Yang 《Communications in Computational Physics》 SCIE 2023年第2期538-567,共30页
This paper studies the geometric boundary representations for Inverse Lax-Wendroff(ILW)method,aiming to develop a practical computer-aided engineering method without body-fitted meshes.We propose the signed distance f... This paper studies the geometric boundary representations for Inverse Lax-Wendroff(ILW)method,aiming to develop a practical computer-aided engineering method without body-fitted meshes.We propose the signed distance function(SDF)representation of the geometric boundary and design an extremely efficient algorithm for foot point calculation,which is particularly in line with the needs of ILW.Theoretical and numerical analyses demonstrate that the SDF representation of geometric boundary can satisfy ILW’s needs better than others.The effectiveness and robustness of our proposed method are verified by simulating initial boundary value computational physical problems of Euler equation for compressible fluids. 展开更多
关键词 Computer-aided engineering Inverse Lax-Wendroff signed distance function Euler equation.
原文传递
基于物体单视图的隐式曲面重建
7
作者 邢燕 牛赛虎 +1 位作者 洪沛霖 檀结庆 《合肥工业大学学报(自然科学版)》 CAS 北大核心 2024年第5期642-648,共7页
基于隐式曲面的三维重建方法在保真度、灵活性和压缩能力方面提供了良好的权衡。文章利用隐式曲面网络学习物体形状的三维表面,首先利用视觉几何群(visual geometry group-16,VGG-16)网络从图像中提取全局特征,对建模空间中的每个采样点... 基于隐式曲面的三维重建方法在保真度、灵活性和压缩能力方面提供了良好的权衡。文章利用隐式曲面网络学习物体形状的三维表面,首先利用视觉几何群(visual geometry group-16,VGG-16)网络从图像中提取全局特征,对建模空间中的每个采样点从VGG-16网络中获取局部特征;其次对每个采样点利用多层感知器(multi-layer perceptron,MLP)进行位置编码得到点特征;然后将全局特征和局部特征分别与点特征串联起来送入2个解码器中,获得隐式场中采样点的符号距离函数(signed distance function,SDF)的大小与符号,并最终得到物体的隐式曲面。文中所提出的方法应用于ShapeNet数据集上进行三维对象重建任务,定性和定量评估均优于现有方法,特别是对于具有孔洞和薄结构的复杂拓扑物体。 展开更多
关键词 三维重建 全局特征 局部特征 深度学习 符号距离函数(SDF)
下载PDF
基于边缘强化神经拉动模型的三维表面重建
8
作者 徐宝昌 王毅豪 +3 位作者 郝围围 尹士轩 王威 李雅飞 《红外与激光工程》 EI CSCD 北大核心 2024年第6期202-212,共11页
通过学习空间点云数据的符号距离函数(Signed Distance Functions, SDFs)进行三维表面重建是当前的研究热点。为重建出高精度的水密模型,神经拉动(Neural-pull, NP)采用点云拉动,以训练同步更新SDFs,但在实际重建过程中,重建模型会因为... 通过学习空间点云数据的符号距离函数(Signed Distance Functions, SDFs)进行三维表面重建是当前的研究热点。为重建出高精度的水密模型,神经拉动(Neural-pull, NP)采用点云拉动,以训练同步更新SDFs,但在实际重建过程中,重建模型会因为点云存在噪声和缺失而导致重建结果不够精细,带来错误的表面重建。针对以上问题,引入边缘提取强化输入点云的边缘信息,提出利用残差学习机制的边缘强化神经拉动模型(Neural Pull based on Edge Enhancement, NPEE)。为确保重建表面平滑的同时能够获取更多的表面细节,该方法在保留原本神经网络用于学习SDFs的基础上引入一个新的网络,利用残差学习机制学习点云的边缘SDFs。同时在原始点云的基础上,引入边缘因子σ,结合学习的边缘SDFs,通过点云边缘的鲁棒提取强化输入点云。为验证算法模型的优化效果,采用目前广泛使用的ABC数据集、斯坦福扫描模型和模拟扫描数据集设计对比实验,实验结果以及评估指标(CD)表明,NPEE可以有效改善神经拉动算法在边缘表面重建的缺陷,同时和其他重建方法相比,NPEE在面对稀疏点云和含噪点云时仍能保证重建的精确性和完整性。 展开更多
关键词 深度学习 三维点云 表面重建 符号距离函数
下载PDF
嵌入式消防疏散标志立体结构对疏散影响的研究
9
作者 季涛 牛慧婷 +2 位作者 苟铭义 张吉友 代张音 《安全》 2024年第1期1-7,共7页
为更充分地发挥嵌入式消防疏散标志在火灾发生时的指示作用,进一步提高疏散效率,运用PsyLab心理实验系统及Pathfinder人员疏散能力模拟软件,从嵌入式消防疏散标志空间角度和凸出距离2个方面入手,探究嵌入式消防疏散标志立体结构对人员... 为更充分地发挥嵌入式消防疏散标志在火灾发生时的指示作用,进一步提高疏散效率,运用PsyLab心理实验系统及Pathfinder人员疏散能力模拟软件,从嵌入式消防疏散标志空间角度和凸出距离2个方面入手,探究嵌入式消防疏散标志立体结构对人员疏散的影响。结果表明:空间角度为5°时可促进人员择向,降低择向反应时间;凸出距离<75mm时,对疏散效率几乎无影响;凸出距离≥75mm时,会对疏散效率产生消极影响。 展开更多
关键词 消防疏散标志 嵌入式 空间角度 凸出距离 疏散效率
下载PDF
基于符号距离场的多体系统碰撞动力学研究
10
作者 张西南 游浦 刘铸永 《力学学报》 EI CAS CSCD 北大核心 2024年第9期2703-2712,共10页
多体系统动力学中的接触碰撞问题是典型的边界非线性问题,对其动力学仿真面临着巨大的数值困难.由于求解过程中需要一直进行复杂的接触碰撞检测,严重地影响了数值计算效率.为了实现对多体系统动力学中接触碰撞问题的快速求解,文章提出... 多体系统动力学中的接触碰撞问题是典型的边界非线性问题,对其动力学仿真面临着巨大的数值困难.由于求解过程中需要一直进行复杂的接触碰撞检测,严重地影响了数值计算效率.为了实现对多体系统动力学中接触碰撞问题的快速求解,文章提出一种改进的基于符号距离场的多体系统动力学接触碰撞检测算法.通过对预先生成的符号距离场进行三线性插值,求解出空间中任意一点距离物体表面的最短距离和法向量.将接触碰撞检测分为全局检测和局部检测两个过程,首先在全局检测时利用OBB包围盒技术对物体之间是否存在潜在接触可能性进行快速判断;然后在局部检测时基于符号距离场信息并结合八叉树结构对接触碰撞检测算法进行优化.分别采用Hertz接触力模型和基于速度的库伦摩擦力模型,建立了多刚体系统非连续动力学方程.最后,通过对典型的算例和空间站交会对接的工程案例进行仿真,验证了所提方法在解决复杂多体系统碰撞动力学问题时的正确性和高效性.该方法可以进一步拓展到复杂构型刚体与柔性体的接触碰撞动力学研究. 展开更多
关键词 符号距离场 碰撞检测 多体系统 八叉树 交会对接
下载PDF
A Workable Solution for Reducing the Large Number of Vehicle and Pedestrian Accidents Occurring on a Yellow Light
11
作者 Pranav Gupta Silki Arora 《Journal of Transportation Technologies》 2024年第1期82-87,共6页
Traffic intersections are incredibly dangerous for drivers and pedestrians. Statistics from both Canada and the U.S. show a high number of fatalities and serious injuries related to crashes at intersections. In Canada... Traffic intersections are incredibly dangerous for drivers and pedestrians. Statistics from both Canada and the U.S. show a high number of fatalities and serious injuries related to crashes at intersections. In Canada, during 2019, the National Collision Database shows that 28% of traffic fatalities and 42% of serious injuries occurred at intersections. Likewise, the U.S. National Highway Traffic Administration (NHTSA) found that about 40% of the estimated 5,811,000 accidents in the U.S. during the year studied were intersection-related crashes. In fact, a major survey by the car insurance industry found that nearly 85% of drivers could not identify the correct action to take when approaching a yellow traffic light at an intersection. One major reason for these accidents is the “yellow light dilemma,” the ambiguous situation where a driver should stop or proceed forward when unexpectedly faced with a yellow light. This situation is even further exacerbated by the tendency of aggressive drivers to inappropriately speed up on the yellow just to get through the traffic light. A survey of Canadian drivers conducted by the Traffic Injury Research Foundation found that 9% of drivers admitted to speeding up to get through a traffic light. Another reason for these accidents is the increased danger of making a left-hand turn on yellow. According to the National Highway Traffic Safety Association (NHTSA), left turns occur in approximately 22.2% of collisions—as opposed to just 1.2% for right turns. Moreover, a study by CNN found left turns are three times as likely to kill pedestrians than right turns. The reason left turns are so much more likely to cause an accident is because they take a driver against traffic and in the path of oncoming cars. Additionally, most of these left turns occur at the driver’s discretion—as opposed to the distressingly brief left-hand arrow at busy intersections. Drive Safe Now proposes a workable solution for reducing the number of accidents occurring during a yellow light at intersections. We believe this fairly simple solution will save lives, prevent injuries, reduce damage to public and private property, and decrease insurance costs. 展开更多
关键词 Traffic Accidents Yellow Light Traffic Light signals INTERSECTION Crashes Collision Traffic Fatalities Traffic Injuries Vehicles SAFETY Speed Limit Driving Pedestrians Bicyclists MOTORCYCLISTS Caution Line Yellow Light Dilemma Left Hand Turn on Yellow distance Smart Road Technology signs signage Autonomous Vehicles AVs Road Safety IoT Internet of Things Infrastructure Accident Reduction Driving Habits Stop Line Red Light Jumping Pedestrian Safety Caution Light Stopping at Intersection Safety at Intersections
下载PDF
基于B样条的(保边界的)高精度符号距离函数重建
12
作者 王昕 王旭辉 《大学数学》 2024年第1期1-7,共7页
针对隐式符号距离函数重建这一问题,提出一种高精度的符号距离函数重建方法.首先,基于快速行进法获得离散的符号距离场;其次,针对离散符号距离场进行B样条自适应拟合;最后,为了提高重建的边界拟合精度,在拟合的目标函数中考虑了边界误差... 针对隐式符号距离函数重建这一问题,提出一种高精度的符号距离函数重建方法.首先,基于快速行进法获得离散的符号距离场;其次,针对离散符号距离场进行B样条自适应拟合;最后,为了提高重建的边界拟合精度,在拟合的目标函数中考虑了边界误差,得到了在边界上具有较高精度的离散符号距离函数重建结果.实验结果表明,通过上述方法获得的隐式符号距离函数重建结果,在保证符号距离函数拟合良好的情况下其零水平集能很好的贴合原始边界. 展开更多
关键词 B样条 符号距离函数 隐式函数 快速行进法 水平集
下载PDF
超多车道出口指路标志前置距离模型研究
13
作者 李美玲 叶新雨 +2 位作者 姚坤 樊兆董 申全军 《山东建筑大学学报》 2024年第4期73-80,共8页
超多车道高速公路出口指路标志前置距离的研究可以为道路管理者和设计者提供参考,并提高超多车道高速公路的安全性和运行效率。文章以车辆驶出的运动过程特性为基础,构建了以车道数为参数的高速公路出口指路标志前置距离理论模型,并标... 超多车道高速公路出口指路标志前置距离的研究可以为道路管理者和设计者提供参考,并提高超多车道高速公路的安全性和运行效率。文章以车辆驶出的运动过程特性为基础,构建了以车道数为参数的高速公路出口指路标志前置距离理论模型,并标定了模型的参数;对比分析了不同主线限速、指路标志设置方式和匝道限速条件下不同车道数的高速公路出口指路标志前置距离。结果表明:在相同条件下,高速公路龙门架式出口指路标志的前置距离不应小于路边直立式的;当高速公路出口指路标志为路边直立式时,双向十车道标志前置距离为2.7、1.7和1.2 km,而双向十二车道标志前置距离则为2.9、1.9和1.4 km;当高速公路出口指路标志为龙门架式时,双向十车道标志前置距离为2.8、1.8和1.3 km,而双向十二车道标志前置距离则为3.0、2.0和1.5 km。 展开更多
关键词 超多车道 高速公路 出口指路标志 前置距离 车道数 参数标定
下载PDF
Sign Language Video Retrieval Based on Trajectory
14
作者 Shilin Zhang Mei Gu 《通讯和计算机(中英文版)》 2010年第9期32-35,共4页
关键词 基于内容的视频检索 手语 编辑距离 距离算法 颜色直方图 字符串 修正方法 内存空间
下载PDF
第二大符号距离特征值属于[-1,(17-√329)/2]的符号图
15
作者 杨博远 李丹 《新疆大学学报(自然科学版)(中英文)》 CAS 2023年第6期676-682,共7页
研究了符号图的第二大符号距离特征值,通过Matlab计算方法构造了符号图的禁用子图,进而刻画了第二大符号距离特征值属于[-1,(17-√329)/2]的所有连通符号图.
关键词 符号图 符号距离矩阵 第二大符号距离特征值 禁用子图
下载PDF
哈希编码优化的IRON逆渲染模型:重建几何与材质 被引量:1
16
作者 张沛全 许威威 《浙江大学学报(理学版)》 CAS CSCD 北大核心 2023年第6期754-760,769,共8页
将神经网络用于场景几何材质的高效表达,结合逆向渲染在二维光度图的监督下重建高质量的网格和材质贴图,为现有的图形学流水线提供服务——神经渲染已成为近年来计算机图形学新的研究热点。在IRON(inverse rendering by optimizing neur... 将神经网络用于场景几何材质的高效表达,结合逆向渲染在二维光度图的监督下重建高质量的网格和材质贴图,为现有的图形学流水线提供服务——神经渲染已成为近年来计算机图形学新的研究热点。在IRON(inverse rendering by optimizing neural SDFs and materials from photometric images)神经渲染模型基础上,通过引入多分辨率哈希编码,采用冻结训练等方法提高原始模型的训练速度。在多个数据集上的对比实验表明,优化后的IRON逆渲染模型训练速度提升了约40%,且重建结果中包含更多细节。 展开更多
关键词 符号距离场 神经渲染 哈希编码
下载PDF
基于稀疏特征改进的单视图表面重建 被引量:2
17
作者 梁春阳 唐红梅 +1 位作者 席建锐 刘鑫 《计算机应用研究》 CSCD 北大核心 2023年第3期925-931,937,共8页
基于深度学习的单视图三维重建是当前的研究热点。为重建出更多的高频细节,SDF-SRN算法引入了位置编码,但在缺乏精确监督时,网络容易过拟合而导致凹凸不平的重建结果。针对这个问题,提出一种基于稀疏特征的网络模型,该模型凭借残差学习... 基于深度学习的单视图三维重建是当前的研究热点。为重建出更多的高频细节,SDF-SRN算法引入了位置编码,但在缺乏精确监督时,网络容易过拟合而导致凹凸不平的重建结果。针对这个问题,提出一种基于稀疏特征的网络模型,该模型凭借残差学习机制,令容易过拟合的网络预测高频残差。通过特征提取网络得到稀疏特征和全局特征,稀疏特征输入到一个超网络中生成预测浅头,该浅头负责预测符号距离函数的低频部分,而全局特征输入到另一个超网络生成另一个浅头来预测高频残差,这两部分通过权重因子构成最终的符号距离函数。频谱分析表明实验结果达到了相应的设计目的;与不同平滑表面重建方案对比,基于残差学习的平滑重建方案可以实现更平滑的表面重建,克服了SDF-SRN过拟合的问题,同时保留足够的细节;与其他先进的单视图重建方法的定性和定量对比结果证明了该方法的优越性。 展开更多
关键词 深度学习 单视图重建 符号距离函数 位置编码 超网络 残差学习
下载PDF
基于多模态传感系统的交通标志夜间视认距离测量方法
18
作者 冯移冬 陈光 +2 位作者 刘宇飞 宋明珠 贾宁 《公路交通科技》 CAS CSCD 北大核心 2023年第S02期263-269,共7页
为快速、准确把握大规模路网交通标志功能性技术状态,特别是标志板夜间视认性能,提出一种基于多模态传感器的标志夜间动态视认距离测量方法。测试人员在车辆行驶至能够看清标志内容的位置时,可通过触发传感器记录所在位置的前视图像、... 为快速、准确把握大规模路网交通标志功能性技术状态,特别是标志板夜间视认性能,提出一种基于多模态传感器的标志夜间动态视认距离测量方法。测试人员在车辆行驶至能够看清标志内容的位置时,可通过触发传感器记录所在位置的前视图像、时间戳以及激光点云数据,再运用时间戳对齐、点云投影及点云分割等算法,实现被测标志动态视认距离的自动测算。结果表明,该方法具有较好的距离估算精度,最大估算误差不超过5 m,满足交通标志夜间视认距离检测要求,大幅提升交通标志夜间视认性评估效率。 展开更多
关键词 交通工程 交通标志 多模态传感器 视认距离测量 激光雷达 点云分割
下载PDF
3.0 T MRI在乳腺癌患者乳头乳晕复合体受侵评估中的应用价值 被引量:1
19
作者 文洁 王猛 +4 位作者 任雅 关剑 刘周 向露 罗德红 《磁共振成像》 CAS CSCD 北大核心 2023年第2期44-49,共6页
目的探讨术前3.0 T MRI检查评估乳腺癌患者中乳头乳晕复合体(nipple areola complex,NAC)受侵的应用价值。材料与方法收集2019年11月至2022年1月期间术前进行乳腺MRI检查并接受手术治疗的原发性可手术乳腺癌患者179例。通过比较术前MRI... 目的探讨术前3.0 T MRI检查评估乳腺癌患者中乳头乳晕复合体(nipple areola complex,NAC)受侵的应用价值。材料与方法收集2019年11月至2022年1月期间术前进行乳腺MRI检查并接受手术治疗的原发性可手术乳腺癌患者179例。通过比较术前MRI和术后组织病理学检查结果,评估MRI征象判断NAC受侵的准确性。结果179例乳腺癌患者中,NAC阳性组40例,NAC阴性139例。乳腺MRI上肿瘤距离乳头的距离≤0.75 cm、乳头回缩、存在连续强化征、乳头乳晕皮肤增厚、单侧乳头强化等征象对诊断NAC受侵有帮助(P<0.05)。通过绘制受试者工作特征曲线,肿瘤距离乳头的距离≤0.75 cm诊断NAC受侵的曲线下面积略高于后四个征象(0.862 vs.0.739、0.800、0.696、0.711)。结论乳腺MRI征象(肿瘤距离乳头的距离、乳头回缩、存在连续强化征、乳头乳晕皮肤增厚、单侧乳头强化)为术前无创性评估乳腺癌NAC受侵情况提供有效方法,可在乳腺癌术前提供更多具有价值的信息。 展开更多
关键词 乳腺癌 乳头乳晕复合体 肿瘤与乳头间的距离 连续强化征 磁共振成像
下载PDF
利用光线跟踪加速欧几里德符号距离场的地图构建
20
作者 唐嘉宁 刘志聪 +3 位作者 李孟霜 彭志祥 谢翠娟 陈云浩 《陕西科技大学学报》 北大核心 2023年第4期158-165,共8页
针对现有小型无人飞行器在复杂未知环境中执行自主探索任务时,存在机载端GPU计算资源不足,在线建图速度慢、探索效率低的问题.本文在传统欧几里德符号距离场(ESDF)方法的基础上,融合光线跟踪原理,加速构建ESDF地图,以提高飞行器在复杂... 针对现有小型无人飞行器在复杂未知环境中执行自主探索任务时,存在机载端GPU计算资源不足,在线建图速度慢、探索效率低的问题.本文在传统欧几里德符号距离场(ESDF)方法的基础上,融合光线跟踪原理,加速构建ESDF地图,以提高飞行器在复杂未知环境中的探索效率.首先使用整数运算提高光线跟踪遍历体素的速度,从而加速体素占用概率的更新;然后通过调整哈希数据结构,减少地图占用内存;最后使用广度优先搜索算法(BFS)实现地图更新与融合.为验证本文方法的有效性,分别在公开数据集、仿真环境和真实环境下,与当前前沿的建图方法进行对比,实验结果表明,本文所提出的方法在三种不同情况下的地图平均更新时间分别减少了72.37%、60.80%和56.79%,显著提高了建图速度,为小型无人飞行器在线探索奠定基础. 展开更多
关键词 地图构建 光线跟踪 符号距离场 梯度优化
下载PDF
上一页 1 2 10 下一页 到第
使用帮助 返回顶部