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Principal Manifolds and Nonlinear Dimensionality Reduction via Tangent Space Alignment 被引量:70
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作者 张振跃 查宏远 《Journal of Shanghai University(English Edition)》 CAS 2004年第4期406-424,共19页
We present a new algorithm for manifold learning and nonlinear dimensionality reduction. Based on a set of unorganized data points sampled with noise from a parameterized manifold, the local geometry of the manifold i... We present a new algorithm for manifold learning and nonlinear dimensionality reduction. Based on a set of unorganized data points sampled with noise from a parameterized manifold, the local geometry of the manifold is learned by constructing an approximation for the tangent space at each point, and those tangent spaces are then aligned to give the global coordinates of the data points with respect to the underlying manifold. We also present an error analysis of our algorithm showing that reconstruction errors can be quite small in some cases. We illustrate our algorithm using curves and surfaces both in 2D/3D Euclidean spaces and higher dimensional Euclidean spaces. We also address several theoretical and algorithmic issues for further research and improvements. 展开更多
关键词 nonlinear dimensionality reduction principal manifold tangent space subspace alignment singular value decomposition.
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Expanders, Group Extensions, Hadamard Manifolds and Certain Banach Spaces
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作者 SHAN LIN Gong Gui-hua 《Communications in Mathematical Research》 CSCD 2019年第4期335-339,共5页
In this note,we prove that expanders cannot be coarsely embedded into group extensions of sequences of groups which are coarsely embeddable into Hardamad manifolds and certain Banach spaces due to the similar concentr... In this note,we prove that expanders cannot be coarsely embedded into group extensions of sequences of groups which are coarsely embeddable into Hardamad manifolds and certain Banach spaces due to the similar concentration theorems. 展开更多
关键词 EXPANDER group extension HADAMARD manifold BANACH space
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Compact Space-like Submanifolds in Pseudo-Riemann Manifold 被引量:1
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作者 SUNHe-jun WUBao-qiang 《Chinese Quarterly Journal of Mathematics》 CSCD 2004年第1期6-15,共10页
We first establish a integral inequality for compact maximal space-like subman-ifolds in pseudo-Riemannian manifolds N^np+p. Then, we investigate compact space-like sub-manifolds and hupersurfaces with parallel second... We first establish a integral inequality for compact maximal space-like subman-ifolds in pseudo-Riemannian manifolds N^np+p. Then, we investigate compact space-like sub-manifolds and hupersurfaces with parallel second fundamental form in N^np+p and some other N^np+pambient spaces. We obtain some distribution theorems for the square norm of the secondfundamental form. 展开更多
关键词 微分几何 子流形 黎曼几何 超曲面
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Secret Sharing Scheme Based on the Differential Manifold
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作者 Bin Li 《Applied Mathematics》 2023年第3期173-181,共9页
In this paper, the concepts of topological space and differential manifold are introduced, and it is proved that the surface determined by function F (x<sub>2</sub>, x<sub>2</sub>, …, x<sub... In this paper, the concepts of topological space and differential manifold are introduced, and it is proved that the surface determined by function F (x<sub>2</sub>, x<sub>2</sub>, …, x<sub>t</sub>) of class C<sup>r</sup> in Euelidean R<sup>t</sup> is a differential manifold. Using the intersection of the tangent plane and the hypernormal of the differential manifold to construct the shared master key of participants, an intuitive, secure and complete (t,n)-threshold secret sharing scheme is designed. The paper is proved to be safe, and the probability of successful attack of attackers is only 1/p<sup>t</sup><sup>-1</sup>. When the prime number p is sufficiently large, the probability is almost 0. The results show that this scheme has the characteristics of single-parameter representation of the master key in the geometric method, and is more practical and easy to implement than the Blakley threshold secret sharing scheme. 展开更多
关键词 Topological space Differential manifold Secret Sharing Tangent Plane Hypernormal
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一种基于流形的机械臂动作构型知识压缩表达方法
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作者 高军礼 贺梓涛 +1 位作者 宋海涛 李忠娟 《信阳师范学院学报(自然科学版)》 CAS 2024年第2期234-239,共6页
针对在机械臂分拣任务中,存在物体形状各异、大小不一、训练神经网络成本过高的问题,提出一种基于流形空间的机械臂快速分拣方法。通过自主设计的一款简易实验装置模拟代替机械臂进行实验。对高维数据进行压缩,结合三维快速凸包求解算法... 针对在机械臂分拣任务中,存在物体形状各异、大小不一、训练神经网络成本过高的问题,提出一种基于流形空间的机械臂快速分拣方法。通过自主设计的一款简易实验装置模拟代替机械臂进行实验。对高维数据进行压缩,结合三维快速凸包求解算法,对体积大小不同的同类物体的流形空间进行分割,以凸包形式将稳定性较高的点集包裹起来。实验结果表明,体积大小不同的同类物体的高稳定流形子空间是一致的。该方法可以通过对一种物体的流形子结构进行尺度放缩,得到不同大小的同类物体的高稳定分拣区域,用于生成高效、可靠的机械臂分拣任务中的6D位姿构型,以提高分拣作业的工作效率。 展开更多
关键词 机械臂 分拣任务 三维凸包 快速凸包法 流形空间
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Representation of Physical Fields as Einstein Manifold
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作者 Vu B. Ho 《Journal of Applied Mathematics and Physics》 2023年第3期599-607,共9页
In this work we investigate the possibility to represent physical fields as Einstein manifold. Based on the Einstein field equations in general relativity, we establish a general formulation for determining the metric... In this work we investigate the possibility to represent physical fields as Einstein manifold. Based on the Einstein field equations in general relativity, we establish a general formulation for determining the metric tensor of the Einstein manifold that represents a physical field in terms of the energy-momentum tensor that characterises the physical field. As illustrations, we first apply the general formulation to represent the perfect fluid as Einstein manifold. However, from the established relation between the metric tensor and the energy-momentum tensor, we show that if the trace of the energy-momentum tensor associated with a physical field is equal to zero then the corresponding physical field cannot be represented as an Einstein manifold. This situation applies to the electromagnetic field since the trace of the energy-momentum of the electromagnetic field vanishes. Nevertheless, we show that a system that consists of the electromagnetic field and non-interacting charged particles can be represented as an Einstein manifold since the trace of the corresponding energy-momentum of the system no longer vanishes. As a further investigation, we show that it is also possible to represent physical fields as maximally symmetric spaces of constant scalar curvature. 展开更多
关键词 General Relativity Einstein manifold Energy-Momentum Tensor Electromagnetic Field Perfect Fluid Maximally Symmetric spaces
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大坝安全监测数据降噪的流形学习方法
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作者 冯燕明 何杨杨 +3 位作者 左生龙 张帅 徐朗 苏怀智 《水利水电科技进展》 CSCD 北大核心 2024年第4期59-64,共6页
针对大坝变形、渗流、应力应变等安全监测数据难以避免受到噪声污染,且传统线性降噪方法去噪效果不佳的问题,提出了基于相空间重构与流形学习相组合的大坝安全监测数据非线性降噪方法。该方法在重构大坝安全监测数据时间序列相空间的基... 针对大坝变形、渗流、应力应变等安全监测数据难以避免受到噪声污染,且传统线性降噪方法去噪效果不佳的问题,提出了基于相空间重构与流形学习相组合的大坝安全监测数据非线性降噪方法。该方法在重构大坝安全监测数据时间序列相空间的基础上,通过交叉应用局部切空间排列方法与极大似然估计、自适应邻域等方法,以重构的相空间为桥梁,提取大坝安全监测数据序列深层次信息,得到降噪后的大坝安全监测数据。工程实测数据验证结果表明,相比小波软阈值法和固定邻域-LTSA法,本文提出的方法降噪效果更优,具有一定的工程应用价值。 展开更多
关键词 大坝安全 监测数据 降噪处理 流形学习 相空间重构
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有亏格为1的Heegaard分解的三维流形中的环面纽结
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作者 徐妍 雷逢春 +1 位作者 李风玲 梁良 《数学年刊(A辑)》 CSCD 北大核心 2024年第1期1-14,共14页
将存在亏格为1的Heegaard分解T’_(1)∪F T’_(2)的三维流形记为M=L(p,q),其中p和q是互素整数,q/p为T’_(2)的纬线在T’_(1)上的斜率.若环面F上的简单闭曲线γ在M中非平凡,则称γ是M中的环面纽结.本文对在M中沿环面纽结作m/n-Dehn手术... 将存在亏格为1的Heegaard分解T’_(1)∪F T’_(2)的三维流形记为M=L(p,q),其中p和q是互素整数,q/p为T’_(2)的纬线在T’_(1)上的斜率.若环面F上的简单闭曲线γ在M中非平凡,则称γ是M中的环面纽结.本文对在M中沿环面纽结作m/n-Dehn手术所得流形进行了分类,并给出了两个实心环体沿边界上平环作融合所得流形是L(p,q)中环面纽结补的特征描述. 展开更多
关键词 H’-分解 透镜空间 环面纽结 Seifert流形
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Cartan-Hadamard流形上关于Lorentz范数的Trudinger-Moser不等式
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作者 张佳杰 《数学杂志》 2024年第4期283-292,共10页
本文研究了Cartan-Hadamard流形上带Lorentz范数的Trudinger-Moser不等式.利用了相关格林函数的逐点估计以及O’Neil不等式,我们得到了该不等式的最佳常数,推广了相应欧氏空间上的结果.
关键词 Trudinger-Moser不等式 LORENTZ空间 RIEMANNIAN流形 负曲率 最佳常数
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正曲率齐性Finsler空间的分类:偶数维情形下的一种新方法(英文)
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作者 徐熙昀 许明 《首都师范大学学报(自然科学版)》 2024年第1期124-130,共7页
本文介绍了正曲率齐性Finsler流形的分类。在偶数维的情形下,给出了一种新方法,证明了偶数维光滑陪集空间上有正曲率齐性Finsler度量,当且仅当其上面有正曲率齐性黎曼度量。
关键词 旗曲率 齐性Finsler空间 不变Finsler度量 正曲率Finsler流形
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A NEW PROOF OF GAFFNEY’S INEQUALITY FOR DIFFERENTIAL FORMS ON MANIFOLDS-WITH-BOUNDARY:THE VARIATIONAL APPROACH à LA KOZONO-YANAGISAWA
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作者 李思然 《Acta Mathematica Scientia》 SCIE CSCD 2022年第4期1427-1452,共26页
Let(M,g_(0))be a compact Riemannian manifold-with-boundary.We present a new proof of the classical Gaffney inequality for differential forms in boundary value spaces over M,via a variational approach a la Kozono-Yanag... Let(M,g_(0))be a compact Riemannian manifold-with-boundary.We present a new proof of the classical Gaffney inequality for differential forms in boundary value spaces over M,via a variational approach a la Kozono-Yanagisawa[Lr-variational inequality for vector fields and the Helmholtz-Weyl decomposition in bounded domains,Indiana Univ.Math.J.58(2009),1853-1920],combined with global computations based on the Bochner technique. 展开更多
关键词 Gaffney’s inequality differential form Sobolev spaces on manifolds Bochner technique variational approach
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A Quantum Representation of the Homogeneous 5D Manifold and the Perelman Mappings of 5D onto Non-Homogeneous Lorentz 4D Manifolds 被引量:2
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作者 Kai Wai Wong Peter Chin Wan Fung Wan Ki Chow 《Journal of Modern Physics》 2019年第5期557-575,共19页
The expression of the Maxwell magnetic monopole was employed to correlate the space to space projection that gives rise to the Gell-Mann standard model, and space to time projection which gives the leptons;and how doe... The expression of the Maxwell magnetic monopole was employed to correlate the space to space projection that gives rise to the Gell-Mann standard model, and space to time projection which gives the leptons;and how does it correlate to the Perelman mappings from the homogeneous 5D manifold to the Lorentz 4D manifold, together with correlating the physical consequences caused by the breaking of the Diagonal Long Range Order [DLRO] of the monopoles quantum states affected by the motion of massive particles in the Lorentz 4D boundary of the 5D manifold, which leads to gravitons and the gravity field via the General Relativity covariant Riemannian 4D curvatures metric equation. 展开更多
关键词 5D HOMOGENEOUS manifold Perelman MAPPINGS Magnetic MONOPOLES space Projections and Topological Symmetries COVARIANT RIEMANNIAN Curvature and Gravity
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Feature Extraction of Kernel Regress Reconstruction for Fault Diagnosis Based on Self-organizing Manifold Learning 被引量:3
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作者 CHEN Xiaoguang LIANG Lin +1 位作者 XU Guanghua LIU Dan 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2013年第5期1041-1049,共9页
The feature space extracted from vibration signals with various faults is often nonlinear and of high dimension.Currently,nonlinear dimensionality reduction methods are available for extracting low-dimensional embeddi... The feature space extracted from vibration signals with various faults is often nonlinear and of high dimension.Currently,nonlinear dimensionality reduction methods are available for extracting low-dimensional embeddings,such as manifold learning.However,these methods are all based on manual intervention,which have some shortages in stability,and suppressing the disturbance noise.To extract features automatically,a manifold learning method with self-organization mapping is introduced for the first time.Under the non-uniform sample distribution reconstructed by the phase space,the expectation maximization(EM) iteration algorithm is used to divide the local neighborhoods adaptively without manual intervention.After that,the local tangent space alignment(LTSA) algorithm is adopted to compress the high-dimensional phase space into a more truthful low-dimensional representation.Finally,the signal is reconstructed by the kernel regression.Several typical states include the Lorenz system,engine fault with piston pin defect,and bearing fault with outer-race defect are analyzed.Compared with the LTSA and continuous wavelet transform,the results show that the background noise can be fully restrained and the entire periodic repetition of impact components is well separated and identified.A new way to automatically and precisely extract the impulsive components from mechanical signals is proposed. 展开更多
关键词 feature extraction manifold learning self-organize mapping kernel regression local tangent space alignment
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Multi-Scale Object Perception with Embedding Textural Space
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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
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Including Space-Time in the Extended Group Cl3* of Relativistic Form-Invariance
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作者 Claude Daviau Jacques Bertrand 《Journal of Modern Physics》 CAS 2022年第8期1147-1156,共10页
The inclusion of space-time in the extended group of relativistic form-invariance, Cl<sub>3</sub>*</sup>, is specified as the inclusion of the whole space-time manifold in this multiplicative Lie gro... The inclusion of space-time in the extended group of relativistic form-invariance, Cl<sub>3</sub>*</sup>, is specified as the inclusion of the whole space-time manifold in this multiplicative Lie group. First physical results presented here are: the geometric origin of the time arrow, a better understanding of the non-simultaneity in optics and a mainly geometric origin for the universe expansion, and its recent acceleration. 展开更多
关键词 space-Time manifold Invariance Group Standard Model Acceleration of Expansion
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ON THE INVARIANT SUBMANIFOLDS OF RIEMANNIAN PRODUCT MANIFOLD
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作者 M.Atceken S.Keles 《Acta Mathematica Scientia》 SCIE CSCD 2004年第4期549-558,共10页
In this paper, the vertical and horizontal distributions of an invariant sub-manifold of a Riemannian product manifold are discussed. An invariant real space form in a Riemannian product manifold is researched. Finall... In this paper, the vertical and horizontal distributions of an invariant sub-manifold of a Riemannian product manifold are discussed. An invariant real space form in a Riemannian product manifold is researched. Finally, necessary and sufficient conditions are given on an invariant submanifold of a Riemannian product manifold to be a locally symmetric and real space form. 展开更多
关键词 Riemannian product manifold mixed geodesic submanifold real space form and almost Riemannian product structure
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面向相交多流形聚类的标签传播算法
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作者 高小方 原玉梁 +1 位作者 温静 白雪飞 《计算机工程》 CAS CSCD 北大核心 2023年第6期90-98,共9页
经典的流形学习算法假设样本数据位于高维单流形上,但在现实生活中的真实数据通常位于高维多流形上,且这些数据往往相互交叠,导致流形学习算法效果不佳。传统的标签传播算法通过相似性矩阵构建连接矩阵,实现良好分离数据的聚类,但不能... 经典的流形学习算法假设样本数据位于高维单流形上,但在现实生活中的真实数据通常位于高维多流形上,且这些数据往往相互交叠,导致流形学习算法效果不佳。传统的标签传播算法通过相似性矩阵构建连接矩阵,实现良好分离数据的聚类,但不能有效聚类相互交叠的多流形数据。针对该问题,提出一种面向相交多流形的标签传播算法LPAMMC。采用局部主成分分析算法确定相交多流形数据的相交区域,并基于混合概率主成分分析(MPPCA)模型和多流形的拓扑结构划分相互交叠的子流形,构建“must-link”和“cannot-link”聚类约束,通过约束构建适合相交多流形数据的传播矩阵,实现标签传播算法。LPAMMC算法通过MPPCA模型和多流形拓扑结构划分出子流形,提高相交多流形数据的聚类精度,且MPPCA模型仅用于多流形数据的相交区域,降低了计算复杂度。实验结果表明,LPAMMC算法不仅具有标签传播算法速度快的特点,且能有效聚类相交多流形数据。在Two spirals数据集上的聚类精度、标准互信息和调整兰德系数取得了与SMMC算法相同的性能,运行时间缩短86.7个百分点。 展开更多
关键词 流形学习 多流形聚类 切空间 相交 标签传播
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Completing Einstein’s Spacetime 被引量:3
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作者 M. S. El Naschie 《Journal of Modern Physics》 2016年第15期1972-1994,共24页
The four-dimensional character of Einstein’s spacetime is generally accepted in mainstream physics as beyond reasonable doubt correct. However the real problem is when we require scale invariance and that this spacet... The four-dimensional character of Einstein’s spacetime is generally accepted in mainstream physics as beyond reasonable doubt correct. However the real problem is when we require scale invariance and that this spacetime be four-dimensional on all scales. It is true that on our classical scale, the 4D decouples into 3D plus one time dimension and that on very large scale only the curvature of spacetime becomes noticeable. However the critical problem is that such spacetime must remain 4D no matter how small the scale we are probing is. This is something of crucial importance for quantum physics. The present work addresses this basic, natural and logical requirement and shows how many contradictory results and shortcomings of relativity and quantum gravity could be eliminated when we “complete” Einstein’s spacetime in such a geometrical gauge invariant way. Concurrently the work serves also as a review of the vast Literature on E-Infinity theory used here. 展开更多
关键词 E-INFINITY Cantorian spacetime SELF-SIMILARITY M-THEORY Kaluza-Klein space Fuzzy Kähler manifolds Continued Fraction Isomorphic Length Geometrical Gauge Invariance
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数字孪生赋能下的互动生成式规划与治理
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作者 杨滔 田颖 徐艳杰 《上海城市规划》 北大核心 2023年第5期4-10,共7页
21世纪以来,数字孪生进入城市规划与治理领域,加快了城市的感知和问题反馈的过程,形成了时间、空间和人之间新的互动机制。数字孪生城市的挑战来自城市的复杂性,提出以人为主的沉浸参与式角度来重新定义空间,强调空间的多维度延伸,以空... 21世纪以来,数字孪生进入城市规划与治理领域,加快了城市的感知和问题反馈的过程,形成了时间、空间和人之间新的互动机制。数字孪生城市的挑战来自城市的复杂性,提出以人为主的沉浸参与式角度来重新定义空间,强调空间的多维度延伸,以空间流形的模型为基础,建立起数字孪生城市的空间表达方式及其升维与降维的计算逻辑。基于此,探讨数字孪生赋能下的“互动生成式”规划模式:通过数字孪生的参数化设计,以人为主体,不断调整和实时反馈城市的各项规划参数,构建不断演进的数字孪生的规划治理系统及政策。 展开更多
关键词 数字孪生城市 空间流形 参与式 城市信息模型 生成式
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Gravitational Space-Time Curve Generation via Accelerated Charged Particles
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作者 Edward A. Walker 《Journal of Modern Physics》 2016年第9期863-874,共12页
A force with an acceleration that is equal to multiples greater than the speed of light per unit time is exerted on a cloud of charged particles. The particles are resultantly accelerated to within an infinitesimal fr... A force with an acceleration that is equal to multiples greater than the speed of light per unit time is exerted on a cloud of charged particles. The particles are resultantly accelerated to within an infinitesimal fraction of the speed of light. As the force or acceleration increases, the particles’ velocity asymptotically approaches but never achieves the speed of light obeying relativity. The asymptotic increase in the particles’ velocity toward the speed of light as acceleration increasingly surpasses the speed of light per unit time does not compensate for the momentum value produced on the particles at sub-light velocities. Hence, the particles’ inertial mass value must increase as acceleration increases. This increase in the particles’ inertial mass as the particles are accelerated produce a gravitational field which is believed to occur in the oscillation of quarks achieving velocities close to the speed of light. The increased inertial mass of the density of accelerated charged particles becomes the source mass (or Big “M”) in Newton’s equation for gravitational force. This implies that a space-time curve is generated by the accelerated particles. Thus, it is shown that the acceleration number (or multiple of the speed of light greater than 1 per unit of time) and the number of charged particles in the cloud density are surjectively mapped to points on a differential manifold or space-time curved surface. Two aspects of Einstein’s field equations are used to describe the correspondence between the gravitational field produced by the accelerated particles and the resultant space-time curve. The two aspects are the Schwarzchild metric and the stress energy tensor. Lastly, the possibility of producing a sufficient acceleration or electromagnetic force on the charged particles to produce a gravitational field is shown through the Lorentz force equation. Moreover, it is shown that a sufficient voltage can be generated to produce an acceleration/force on the particles that is multiples greater than the speed of light per unit time thereby generating gravity. 展开更多
关键词 Charged Particles Accelerated Particles Inertial Mass Gravitational Force Einstein’s Field Equations space-Time manifold Schwardchild Metric Stress Energy Tensor Surjective Mapping Lorentz Force
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