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Space-time principles of reducing stripping in furrow pits 被引量:1
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作者 Shixiong Zhang, Guozhu Zeng, and Tao PengCollege of Resources and Environment Engineering, Wuhan University of’Technologv, Wuhan 430070, China 《Journal of University of Science and Technology Beijing》 CSCD 2003年第1期16-17,共2页
The lower slope of furrow pits has following special features: small extent of weathering destruction, short time of production blasting damage, good arching effect of lower slope with small curvature radius, and good... The lower slope of furrow pits has following special features: small extent of weathering destruction, short time of production blasting damage, good arching effect of lower slope with small curvature radius, and good bottom effect of a pit end for transferring and bearing initial horizontal stresses in lower slope. The new principles provided theoretical basis for convex slope in furrow pits to reduce stripping. Similar phenomena and examples are supplied simultaneously. 展开更多
关键词 furrow pits space-time principle STRIPPING
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Earth Ecosystem Theory: Ⅱ Segm entation and Com-position Principles 被引量:1
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作者 Yang Dongfang Wang Fengyou +2 位作者 He Huazhong Zhu Sixi Wu Yunjie 《Meteorological and Environmental Research》 CAS 2014年第10期1-2,共2页
We firstly put forward the definitions and principles of ecosystem segmentation and composition, and elaborate five kinds of characteristics of ecosystem segmentation and composition. Results show that ecosystem segme... We firstly put forward the definitions and principles of ecosystem segmentation and composition, and elaborate five kinds of characteristics of ecosystem segmentation and composition. Results show that ecosystem segmentation and composition are actually its space segmentation and composition, and time change decides change and succession of any ecosystems. Via temporal-spatial change of ecosystem and segmentation and composition, change and succession trend of ecosystem and future development are determined, which lays foundation for analyzing structure and composition of earth ecosystem. 展开更多
关键词 Earth ecosystem segmentation COMPOSITION DEFINITION principle China
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On Segmentation of Moving Objects by Integrating PCA Method with the Adaptive Background Model 被引量:1
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作者 Noureldaim Emadeldeen Mohammed Jedra Noureldeen Zahid 《Journal of Signal and Information Processing》 2012年第3期387-393,共7页
Tracking and segmentation of moving objects are suffering from many problems including those caused by elimination changes, noise and shadows. A modified algorithm for the adaptive background model is proposed by link... Tracking and segmentation of moving objects are suffering from many problems including those caused by elimination changes, noise and shadows. A modified algorithm for the adaptive background model is proposed by linking Gaussian mixture model with the method of principal component analysis PCA. This approach utilizes the advantage of the PCA method in providing the projections that capture the most relevant pixels for segmentation within the background models. We report the update on both the parameters of the modified method and that of the Gaussian mixture model. The obtained results show the relatively outperform of the integrated method. 展开更多
关键词 PIXELS GAUSSIAN MIXTURE MODEL principle Component Analysis Background MODEL Noise Process segmentation
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Physics of Clocks in Absolute Space-Time 被引量:3
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作者 Edwin Eugene Klingman 《Journal of Modern Physics》 2020年第12期1950-1968,共19页
20th century physics experimentally established beyond doubt the fact that moving clocks read differently from “static” clocks. This fact is typically interpreted as support for special relativity. On the other hand... 20th century physics experimentally established beyond doubt the fact that moving clocks read differently from “static” clocks. This fact is typically interpreted as support for special relativity. On the other hand, the same century produced proof that clocks at various locations in the gravitational field also read differently, and this fact is explained by general relativity, which is, in general, not Lorentz transformable. This paper establishes a common framework for the physics of clocks in these different situations. 展开更多
关键词 RELATIVITY Time Dilation space-time Ontology Clock Slowdown Inertial Clocks Absolute Space and Time Inertial Mass Covariance principle Ideal Clocks
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Was Polchinski Wrong? Colombeau Distributional Rindler Space-Time with Distributional Levi-CivitàConnection Induced Vacuum Dominance. Unruh Effect Revisited
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作者 Jaykov Foukzon Alexander Potapov Elena Men’kova 《Journal of High Energy Physics, Gravitation and Cosmology》 2018年第2期361-440,共80页
The vacuum energy density of free scalar quantum field in a Rindler distributional space-time with distributional Levi-Cività connection is considered. It has been widely believed that, except in very extreme sit... The vacuum energy density of free scalar quantum field in a Rindler distributional space-time with distributional Levi-Cività connection is considered. It has been widely believed that, except in very extreme situations, the influence of acceleration on quantum fields should amount to just small, sub-dominant contributions. Here we argue that this belief is wrong by showing that in a Rindler distributional background space-time with distributional Levi-Cività connection the vacuum energy of free quantum fields is forced, by the very same background distributional space-time such a Rindler distributional background space-time, to become dominant over any classical energy density component. This semiclassical gravity effect finds its roots in the singular behavior of quantum fields on a Rindler distributional space-times with distributional Levi-Cività connection. In particular we obtain that the vacuum fluctuations have a singular behavior at a Rindler horizon . Therefore sufficiently strongly accelerated observer burns up near the Rindler horizon. Thus Polchinski’s account doesn’t violate the Einstein equivalence principle. 展开更多
关键词 VACUUM Energy Density Rindler Distributional space-time Levi-Cività CONNECTION Semiclassical Gravity Effect EINSTEIN EQUIVALENCE principle space-time EINSTEIN EQUIVALENCE principle
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The Quaternion Structure of Space-Time and Arrow of Time
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作者 Ying-Qiu Gu 《Journal of Modern Physics》 2012年第7期570-580,共11页
In fundamental theories of physics, the dynamical equations all have time inversion invariance. Except for the evolution of some simple system which has realistic inverse processes, but for a slightly more complicated... In fundamental theories of physics, the dynamical equations all have time inversion invariance. Except for the evolution of some simple system which has realistic inverse processes, but for a slightly more complicated system, the evolution processes are irreversible. This is the problem of arrow of time, which is always warmly debated. In different point of view, we find there may have some conceptual misunderstanding in the controversy: 1) The realization of an inverse process does not mean the time of the system goes backward. 2) The principles of relativity and covariance are the constraints to physical laws, but not constraints to specific solutions. The equations must be covariant, but the solutions are not definitely symmetric. 3) Time is a global property of the universe, which is a measurement of the evolution process of the universe. The internal time of a matter system reflecting its internal evolution speed also takes this cosmic time as a unified background and standard of measurement. 4) The universe has a unified cosmic time T and a cosmic space related to this cosmic time. They are objective and absolute. 5) The eigensolution of a spinor is a critical state losing time concept, which responses the interaction of environment with some uncertainty, then the evolution process of the world is not uniquely determined. 6) The non-uniqueness of the evolution process means that the inverse process is absent. So for a world including spinors, the evolution is essentially irreversible. In this paper, according to the widely accepted principles and direct calculations of transformation, we reveal the misunderstandings in the usual controversy, and then give more natural and reasonable explanations for structure of space-time and arrow of time. 展开更多
关键词 ARROW of Time Invariance The principle of RELATIVITY QUATERNION STRUCTURE of space-time SIMULTANEITY
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Nature of Black Holes and Space-Time around Them
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作者 Amir Ali Tavajoh 《Journal of High Energy Physics, Gravitation and Cosmology》 2017年第1期96-105,共10页
Based on the Mach’s principle, black holes warp the space time in a way that geodesic for every object which is moving toward black hole starts to bend and object starts to rotate around the black hole. Even light ca... Based on the Mach’s principle, black holes warp the space time in a way that geodesic for every object which is moving toward black hole starts to bend and object starts to rotate around the black hole. Even light cannot be able to escape from the strong gravitational field of black hole and all the light like paths will warp so as to fall farther to the hole. Before arriving to the Schwarzschild’s Sphere, object faces with length extension because of the difference between amount of tidal forces on the nearest and furthest points of object that take the object apart and after passing the Schwarzschild’s sphere, based on the Special relativity of Einstein, the parts of object face with length contraction. In comparison between strange stars and black holes we conclude that core of strange stars has a temperature and pressure not sufficient for up and down quarks and they turn into strange ones. However, in core of black holes, because of massive stars and hot gases falling into it, they are always in a high temperature and pressure. So they can be made up of up and down quarks. At the Ergo sphere Region of black hole, a particle that gets into it will divide into 2 pieces, one of them falls into the black hole and another gets out of the Schwarzschild sphere very fast and it’s called the black hole radiation. According to the Diagram drawn by R. Rafini and J. Weeler, an object gets out of white hole in past space-time, it can be able to send signals to us and we can receive it but black hole which is located in future space-time, after object enters to the Schwarzschild’s Sphere, the signals it sends won’t be received. In order to reach the third space-time which is like a mirror to our universe, our speed needs to exceed the speed of light to pass the Einstein-Rosen Bridge. As a conclusion, structure of black holes can be made up of up and down quarks and everything falls into the black hole, collapses and turns into a bunch of quarks. Space-time around black holes, based on Rafini-Weeler diagram, is like a frontier between our space-time and other space-times. So it can be possible to reach past space-time and other space-times. 展开更多
关键词 General RELATIVITY GEODESIC Rafini-Weeler Diagram STRANGE Stars Einstein-Rosen Bridge Schwarzschild’s SPHERE Ergo SPHERE space-time Curvature Time Warp Special RELATIVITY Mach’s principle
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A New Version of Special Relativity Absorbed the Uncertainty Principle: Its Content as Well as Application and Experimental Test
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作者 Dapeng Qian 《Journal of Modern Physics》 2014年第12期1146-1166,共21页
Based on the space spherical symmetry of 3-dimensional and the translational symmetry of time and the uncertainty principle, a 4-dimensional space-time cylinder model of quarks and leptons is established. With this mo... Based on the space spherical symmetry of 3-dimensional and the translational symmetry of time and the uncertainty principle, a 4-dimensional space-time cylinder model of quarks and leptons is established. With this model, equations of the special relativity can be extended more perfectly, thereby achieving a unity of the special relativity and quantum mechanics in deeper level. New equations can not only interpret issues explained by old equations but also solve several important pending problems. For example, a formula to strictly calculate the coefficient ξ of Lorentz invariance violation (LIV) is derived, to above 4 × 1019 eV UHECR protons the calculated |ξ| -30, although there is the LIV effect it is too weak to change the GZK cutoff, which is consistent with observations of HiRes and Auger;Also, a relation formula between the Hubble constant and several basic constants is derived, thus theoretically calculated H0 = 70.937 km·s-1·Mpc-1, which is well consistent with the final observation result of HST Key Project. In addition, an unusual effect predicted by new equations can be experimentally tested in the electron storage ring;a preliminary experiment result has hinted its signs of existence. 展开更多
关键词 Special Relativity Uncertainty principle Cylinder Model with Intrinsic 4-Dimensional space-time of Quarks/Leptons Lorentz Invariance Violation GZK Cutoff of UHECR Planck ENERGY HUBBLE Constant Super-High ENERGY ELECTRON ELECTRON Storage Ring
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基于上下文提取与注意力融合的遮挡服装图像分割
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作者 顾梅花 花玮 +1 位作者 董晓晓 张晓丹 《纺织学报》 EI CAS CSCD 北大核心 2024年第5期155-164,共10页
针对遮挡服装图像分割准确率低的问题,提出一种融合上下文提取与注意力机制的遮挡服装图像实例分割方法。以Mask R-CNN为基础网络,首先采用上下文提取模块优化ResNet的输出特征,通过融合不同速率的多路径特征从多个感受野中捕获图像的... 针对遮挡服装图像分割准确率低的问题,提出一种融合上下文提取与注意力机制的遮挡服装图像实例分割方法。以Mask R-CNN为基础网络,首先采用上下文提取模块优化ResNet的输出特征,通过融合不同速率的多路径特征从多个感受野中捕获图像的上下文信息,强化遮挡服装特征表示的识别及提取能力;然后引入通道注意力机制与空间注意力机制的残差连接,自适应地专注于捕捉遮挡服装图像的空间和通道维度上的语义相互依赖关系,降低上下文提取模块在处理特征图时因冗余的上下文关系扩大造成误定位与误识别的概率;最后,采用目标检测损失函数CIoU计算原理作为非极大值抑制的评判标准,关注预测框和真实框的重叠与非重叠区域,最大程度地选择遮挡服装的最优目标框,使预测框更加贴近真实框。结果表明,与其它方法相比,改进方法显著改善了不同遮挡程度服装图像的误分割现象,能提取出更精确的服装实例,其对遮挡服装图像的平均分割精度比原模型提升了4.4%。 展开更多
关键词 图像分割 遮挡服装 上下文提取 注意力机制 CIoU计算原理
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宽体飞机地面主轮协同转弯控制律设计
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作者 李晶 杨世海 +1 位作者 耿计凯 陆清 《飞控与探测》 2024年第3期15-21,共7页
主轮协同转弯技术能有效提高飞机的地面机动性,降低主起落架在转弯过程中受到的附加侧向扭矩,减小重载飞机地面转弯半径,但目前实现此技术的前主轮转角控制律设计方法尚不明确。提出以主起落架受力为约束条件,计算不同滑行速度下的前主... 主轮协同转弯技术能有效提高飞机的地面机动性,降低主起落架在转弯过程中受到的附加侧向扭矩,减小重载飞机地面转弯半径,但目前实现此技术的前主轮转角控制律设计方法尚不明确。提出以主起落架受力为约束条件,计算不同滑行速度下的前主轮转角关系,在全速度范围内进行分段选择并离散化,据此设计前主轮协同转弯控制律,以原理样机为对象进行仿真分析,验证了该控制律能有效降低两侧主起落架扭矩和的峰值。提出的设计方法对多轮系地面运载装备的复合转弯控制律设计具有一定的理论指导意义。 展开更多
关键词 宽体飞机 前主轮转角关系 协同转弯控制律 主起落架扭矩和 离散分段原则
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基于单线激光雷达的道路区域分割
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作者 李宏 赵礼刚 张浩傑 《机床与液压》 北大核心 2024年第21期57-63,共7页
针对单线激光雷达在进行道路区域分割时出现的识别不准确以及精度问题,研究一种基于最大熵原理提取自适应阈值,并通过滑动窗口法实现道路区域分割的方法。利用中值滤波对原始点云数据进行预处理,以减少噪声和异常值产生的影响;结合最大... 针对单线激光雷达在进行道路区域分割时出现的识别不准确以及精度问题,研究一种基于最大熵原理提取自适应阈值,并通过滑动窗口法实现道路区域分割的方法。利用中值滤波对原始点云数据进行预处理,以减少噪声和异常值产生的影响;结合最大熵原理提取的自适应阈值和滑动窗口算法完成对道路区域点云的分割;最后基于概率论的方法确定道路边界点云。通过对3种不同类型的结构化道路进行实验,得到路面、障碍物以及路沿的识别准确率依次为96.88%、86.82%、95.50%,证明了该方法的有效性和适用性。 展开更多
关键词 单线激光雷达 最大熵原理 移动窗口 道路区域分割
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基于神经网络图像识别技术的放顶煤煤矸自动识别方法
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作者 范忠明 《自动化技术与应用》 2024年第10期39-42,共4页
放顶煤煤矸识别影响着整个综放工作面的开采效率,可以解决欠放和过放问题,使工人远离放煤工作面。提出基于神经网络图像识别技术的放顶煤煤矸自动识别方法。结合多阈值Qtsu分割算法和边缘检测方法,将图像分割为煤矸层、烟煤层和背景层,... 放顶煤煤矸识别影响着整个综放工作面的开采效率,可以解决欠放和过放问题,使工人远离放煤工作面。提出基于神经网络图像识别技术的放顶煤煤矸自动识别方法。结合多阈值Qtsu分割算法和边缘检测方法,将图像分割为煤矸层、烟煤层和背景层,在煤矸层中利用灰度共生矩阵提取图像特征,在神经网络中加入模糊补偿原理,将提取的特征输入优化后的神经网络中,完成放顶煤煤矸自动识别。实验结果表明,所提方法的分割精度高、识别精度高、复杂度低。 展开更多
关键词 神经网络 图像分割 放顶煤煤矸识别 边缘检测 模糊补偿原理 特征提取
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十二经脉四肢远端穴位与脊髓神经节段支配规律的关系 被引量:20
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作者 王金金 蒋松鹤 +2 位作者 李莎莎 蒋培伟 楼新法 《中华中医药学刊》 CAS 2008年第6期1272-1273,共2页
目的:探讨十二经脉四肢远端穴位的肌层神经节段支配情况,进一步研究临床针刺"节段支配规律"的适用范围。方法:从十二经脉四肢远端穴位层次解剖的肌肉分布情况,观察其各层次肌肉相应的脊髓神经节段支配。结论:与具有"节... 目的:探讨十二经脉四肢远端穴位的肌层神经节段支配情况,进一步研究临床针刺"节段支配规律"的适用范围。方法:从十二经脉四肢远端穴位层次解剖的肌肉分布情况,观察其各层次肌肉相应的脊髓神经节段支配。结论:与具有"节段支配规律"的躯干部穴位相比,具有相对特异的远道治疗作用的四肢远端穴位则与"节段支配规律"无关,另有其他规律。 展开更多
关键词 腧穴 针刺 规律 神经节段 肌节
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图像分割中的马尔可夫随机场方法综述 被引量:64
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作者 李旭超 朱善安 《中国图象图形学报》 CSCD 北大核心 2007年第5期789-798,共10页
马尔可夫随机场方法是图像分割中一个极为活跃的研究方向。本文介绍了基于马尔可夫随机场模型的一般理论与图像的关系,给出它在图像分割中的通用框架:包括空域和小波域图像模型的建立、最优准则的选取、标号数的确定、图像模型参数的估... 马尔可夫随机场方法是图像分割中一个极为活跃的研究方向。本文介绍了基于马尔可夫随机场模型的一般理论与图像的关系,给出它在图像分割中的通用框架:包括空域和小波域图像模型的建立、最优准则的选取、标号数的确定、图像模型参数的估计和图像分割的实现,评述了其在图像分割中的应用,展望其发展的方向。 展开更多
关键词 马尔可夫随机场 图像分割 贝叶斯准则 参数估计
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矩不变调整的二维Shannon熵图像分割及其快速实现 被引量:5
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作者 张新明 李双群 郑延斌 《计算机科学》 CSCD 北大核心 2012年第1期276-280,共5页
为了克服二维Shannon熵阈值法的缺陷,提出了一种使用矩不变法来调整二维直方图斜分Shannon熵的阈值分割方法。首先将二维直方图斜分原理运用到两种Shannon熵阈值法中,然后利用矩不变法从两种熵阈值法获取的阈值中选择最佳阈值,并提出二... 为了克服二维Shannon熵阈值法的缺陷,提出了一种使用矩不变法来调整二维直方图斜分Shannon熵的阈值分割方法。首先将二维直方图斜分原理运用到两种Shannon熵阈值法中,然后利用矩不变法从两种熵阈值法获取的阈值中选择最佳阈值,并提出二维直方图斜分Shannon熵阈值法的一般递推算法,最后将二维直方图分布特性与这种算法有机结合得到新型快速的递推算法。实验结果表明,提出的方法不仅分割效果优于当前的二维直方图斜分的最大熵阈值法,而且运行速度更快,约快4倍。 展开更多
关键词 图像分割 阈值化 二维直方图斜分 矩不变法 Shannon熵
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基于模糊最大熵原则的地图图像分割 被引量:4
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作者 郭玲 周献中 《计算机应用》 CSCD 北大核心 2002年第11期18-19,共2页
在分析地图图像特征的基础上 ,结合直方图和最大模糊熵原则 ,提出地图图像分割的自动阈值算法。通过多幅真实地图的实验表明 ,用该算法分割得到的黑版图不但保持了线划的连续性 ,而且对边缘的定位准确 ,便于识别。
关键词 模糊最大熵原则 地图图像分割 阈值 地理信息系统 图像处理 计算机视觉
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折流板换热器的数值模拟及场协同分析 被引量:29
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作者 严良文 王志文 《石油机械》 北大核心 2005年第4期13-15,75,共3页
在PHOENICS—3 .5 .1程序的基础上, 采用多孔介质模型, 以及体积多孔度、表面渗透度和各向异性的分布阻力来处理换热器内的管束; 用分布热源考虑管侧流体对壳侧流体的影响,对单弓形折流板换热器的壳程流场和温度场做了数值模拟。结果表... 在PHOENICS—3 .5 .1程序的基础上, 采用多孔介质模型, 以及体积多孔度、表面渗透度和各向异性的分布阻力来处理换热器内的管束; 用分布热源考虑管侧流体对壳侧流体的影响,对单弓形折流板换热器的壳程流场和温度场做了数值模拟。结果表明: (1) 采用换热器三维流动计算模型和k—ε湍流模型能较好地模拟折流板换热器内的流场分布; (2) 通过数值模拟可直观地了解换热器内的流动状态, 确定换热器的高、低速区和旋涡区。低速区和旋涡区换热效果差,管子易结垢, 而高速区换热效率高, 但管子易被冲蚀, 且阻力较大, 应予改进; (3) 换热器中间段的场协同性较好, 出入口处的场协同性较差, 应尽量减小其结构尺寸, 或采用导流筒式结构。 展开更多
关键词 换热器 弓形折流板 壳程 场协同 换热效率 管束 结垢 三维流动 换热效果 数值模拟
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变高度薄壁箱梁的剪力滞 被引量:35
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作者 罗旗帜 吴幼明 刘光栋 《铁道学报》 EI CAS CSCD 北大核心 2003年第5期81-87,共7页
考虑了3个不同的剪滞纵向位移差函数以反映薄壁箱梁不同宽度翼板的剪滞变化幅度,提出了一种能对工程中常用的变高度梯形截面箱梁剪力滞及剪切变形效应进行分析的方法。应用能量变分原理,导出了箱梁受横向荷载作用下的剪滞控制微分方程... 考虑了3个不同的剪滞纵向位移差函数以反映薄壁箱梁不同宽度翼板的剪滞变化幅度,提出了一种能对工程中常用的变高度梯形截面箱梁剪力滞及剪切变形效应进行分析的方法。应用能量变分原理,导出了箱梁受横向荷载作用下的剪滞控制微分方程和边界条件,获得相应的闭合解。在理论解的基础上,进而建立一种考虑剪滞剪切效应的有限段模型。进行了有机玻璃模型试验,并对模型桥作了有限段法和有限元法的数值计算,计算值与试验结果均吻合良好。 展开更多
关键词 变高度箱梁 剪力滞效应 能量变分原理 有限段法 模型试验
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一种新的肝肿瘤CT图像分割方法 被引量:3
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作者 陈灵娜 罗扬 陈增科 《计算机工程与应用》 CSCD 北大核心 2009年第34期222-224,共3页
传统的分割方法难以实现医学图像准确地分割,提出了基于最大信息熵原理的医学图像分割方法。该方法集成了阈值分割、边界跟踪和数学形态学,提高了分割的精度和速度。分析和实验结果表明,采用该方法对肝肿瘤CT图像进行分割时,能自动准确... 传统的分割方法难以实现医学图像准确地分割,提出了基于最大信息熵原理的医学图像分割方法。该方法集成了阈值分割、边界跟踪和数学形态学,提高了分割的精度和速度。分析和实验结果表明,采用该方法对肝肿瘤CT图像进行分割时,能自动准确地提取出医生感兴趣的区域。 展开更多
关键词 医学图像分割 最大熵原理 阈值分割 边界跟踪 数学形态学
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数字图像处理中的图像分割技术及其应用 被引量:17
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作者 张晶 王黎 +3 位作者 高晓蓉 王泽勇 周小红 彭建平 《信息技术》 2010年第11期36-39,43,共5页
图像分割是数字图像处理中最为困难的任务之一,到目前为止仍没有适用于所有图像的通用图像分割方法。从图像分割技术的基本原理出发,比较全面地总结了有代表性的图像分割方法,在此基础之上,给出了在机车检测领域、生物医学领域和遥感图... 图像分割是数字图像处理中最为困难的任务之一,到目前为止仍没有适用于所有图像的通用图像分割方法。从图像分割技术的基本原理出发,比较全面地总结了有代表性的图像分割方法,在此基础之上,给出了在机车检测领域、生物医学领域和遥感图像领域中这些图像分割方法的应用,最后对图像分割的发展趋势给予了展望。 展开更多
关键词 数字图像 基本原理 分割方法 应用
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