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The Strange Relationship between the Momentum of a Photon Emitted from an Electron and the Momentum Acquired by the Electron
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作者 Koshun Suto 《Journal of Applied Mathematics and Physics》 2024年第7期2652-2664,共13页
In quantum mechanics, the energy of a hydrogen atom is minimized when the principal quantum number n is 1. However, the author has previously pointed out that the hydrogen atom has a state where n=0. An electron in th... In quantum mechanics, the energy of a hydrogen atom is minimized when the principal quantum number n is 1. However, the author has previously pointed out that the hydrogen atom has a state where n=0. An electron in the state where n=0has zero rest mass energy. However, a hydrogen atom has an energy level even lower than the n=0state. This is hard to accept from the standpoint of common sense. Thus, the author has previously pointed out that an electron at the energy level where n=0has zero energy because the positive energy mec2and negative energy −mec2cancel each other out. This paper elucidates the strange relationship between the momentum of a photon emitted when a hydrogen atom is formed by an electron with such characteristics, and the momentum acquired by the electron. 展开更多
关键词 Einstein’s Energy-momentum Relationship Energy-momentum Relationship in a Hydrogen Atom momentum of a Photon momentum of a Electron Negative Energy Specific to the Electron Dark Matter
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A Theoretical Analysis of the Acceleration and the Angular Momentum of the Universe
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作者 Ardeshir Irani 《Journal of High Energy Physics, Gravitation and Cosmology》 CAS 2024年第1期101-105,共5页
The loss of Baryonic Matter through Black Holes from our spatial 3-D Universe into its 4th dimension as Dark Matter, is used along with the Conservation of Angular Momentum Principle to prove theoretically the acceler... The loss of Baryonic Matter through Black Holes from our spatial 3-D Universe into its 4th dimension as Dark Matter, is used along with the Conservation of Angular Momentum Principle to prove theoretically the accelerated expansion of the 3-D Universe, as has already been confirmed experimentally being awarded the 2011 Nobel Prize in Physics. Theoretical calculations can estimate further to indicate the true nature of the acceleration;that the outward acceleration is due to the rotation of the Universe caused by Dark Energy from the Void, that the acceleration is non-linear, initially increasing from zero for the short period of about a Million years at a constant rate, and then leveling off non-linearly over extended time before the outward acceleration begins to decrease in a non-linear fashion until it is matched by the gravitational attraction of the matter content of 4D Space and the virtual matter in 3-D Vacuum Space. m = m(4D) + m(Virtual). The rotation of our 3D Universe will become constant once all 3D matter has entered 4D space. As the 3-D Universe tries to expand further it will be pulled inward by its gravitational attraction and will then keep on oscillating about a final radius r<sub>f</sub> while it also keeps on oscillating at right angles to the radius r<sub>f</sub> around final angular velocity ω<sub>f</sub>, until it becomes part of the 4-D Universe. The constant value of the Angular Momentum of our Universe is L = . 展开更多
关键词 3-D Baryonic Matter 3-D Virtual Matter 4-D Dark Matter Non-Linear Acceleration Final Radius Final Angular Velocity Conservation of Angular momentum Principle
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A Novel Momentum-Based Measure for Online Portfolio Algorithm
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作者 Xiaoting Lv Cuiyin Huang Hongliang Dai 《Journal of Computer and Communications》 2024年第9期1-21,共21页
In recent years, digital investment portfolios have become a significant area of interest in the field of machine learning. To tackle the issue of neglecting the momentum effect in risk asset prices within the follow-... In recent years, digital investment portfolios have become a significant area of interest in the field of machine learning. To tackle the issue of neglecting the momentum effect in risk asset prices within the follow-the-winner strategy and to evaluate the significance of this effect, a novel measure of risk asset price momentum trend is introduced for online investment portfolio research. Firstly, a novel approach is introduced to quantify the momentum trend effect, which is determined by the product of the slope of the linear regression model and the absolute value of the linear correlation coefficient. Secondly, a new investment portfolio optimization problem is established based on the prediction of future returns. Thirdly, the Lagrange multiplier method is used to obtain the analytical solution of the optimization model, and the soft projection optimization algorithm is used to map the analytical solution to obtain the investment portfolio of the model. Finally, experiments are conducted on five benchmark datasets and compared with popular investment portfolio algorithms. The empirical findings indicate that the algorithm we are introduced is capable of generating higher investment returns, thereby establishing its efficacy for the management of the online investment portfolios. 展开更多
关键词 Machine Learning Online Portfolio Selection momentum Effect Significance Algorithmic Trading
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Boundary Conditions for Momentum and Vorticity at an Interface between Two Fluids
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作者 Korekazu Ueyama 《Journal of Applied Mathematics and Physics》 2024年第1期16-33,共18页
Boundary conditions for momentum and vorticity have been precisely derived, paying attention to the physical meaning of each mathematical expression of terms rigorously obtained from the basic equations: Navier-Stokes... Boundary conditions for momentum and vorticity have been precisely derived, paying attention to the physical meaning of each mathematical expression of terms rigorously obtained from the basic equations: Navier-Stokes equation and the equation of vorticity transport. It has been shown first that a contribution of fluid molecules crossing over a conceptual surface moving with fluid velocity due to their fluctuating motion is essentially important to understanding transport phenomena of momentum and vorticity. A notion of surface layers, which are thin layers at both sides of an interface, has been introduced next to elucidate the transporting mechanism of momentum and vorticity from one phase to the other at an interface through which no fluid molecules are crossing over. A fact that a size of  δV, in which reliable values of density, momentum, and velocity of fluid are respectively defined as a volume-averaged mass of fluid molecules, a volume-averaged momentum of fluid molecules and a mass-averaged velocity of fluid molecules, is not infinitesimal but finite has been one of the key factors leading to the boundary conditions for vorticity at an interface between two fluids. The most distinguished characteristics of the boundary conditions derived here are the zero-value conditions for a normal component of momentum flux and tangential components of vorticity flux, at an interface. 展开更多
关键词 Boundary Condition for Vorticity Surface Layer INTERFACE momentum Flux Vorticity Flux
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Momentum as Translations at Conformal Infinity
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作者 Richard James Petti Jacob Luke Graham 《Journal of Applied Mathematics and Physics》 2024年第4期1522-1540,共19页
Although General Relativity is the classic example of a physical theory based on differential geometry, the momentum tensor is the only part of the field equation that is not derived from or interpreted with different... Although General Relativity is the classic example of a physical theory based on differential geometry, the momentum tensor is the only part of the field equation that is not derived from or interpreted with differential geometry. This work extends General Relativity and Einstein-Cartan theory by augmenting the Poincaré group with projective (special) conformal transformations, which are translations at conformal infinity. Momentum becomes a part of the differential geometry of spacetime. The Lie algebra of these transformations is represented by vectorfields on an associated Minkowski fiber space. Variation of projective conformal scalar curvature generates a 2-index tensor that serves as linear momentum in the field equations of General Relativity. The computation yields a constructive realization of Mach’s principle: local inertia is determined by local motion relative to mass at conformal infinity in each fiber. The vectorfields have a cellular structure that is similar to that of turbulent fluids. 展开更多
关键词 Projective Symmetry Conformal Symmetry momentum General Relativity Einstein-Cartan Mach’s Principle
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Intrinsic Spin Angular Momentum of Electron Relation to the Discrete Indivisible Quantum of Time Kshana or Moment
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作者 Shesharao M. Wanjerkhede 《Journal of Modern Physics》 2024年第9期1337-1352,共16页
The frequency of any periodic event can be defined in terms of units of Time. Planck constructed a unit of time called the Plank time from other physical constants. Vyasa defined a natural unit of time, kshana, or mom... The frequency of any periodic event can be defined in terms of units of Time. Planck constructed a unit of time called the Plank time from other physical constants. Vyasa defined a natural unit of time, kshana, or moment based on the motion of a fundamental particle. It is the time taken by an elementary particle, to change its direction from east to north. According to Vyasa, kshana is discrete, exceedingly small, indivisible, and is a constant time quantum. When the intrinsic spin angular momentum of an electron was related to the angular momentum of a simple thin circular plate, spherical shell, and solid sphere model of an electron, we found that the value of kshana in seconds was equal to ten to a power of minus twenty-one second. The disc model for the spinning electron provides an accurate value of the number of kshanas per second as determined previously and compared with other spinning models of electrons. These results indicate that the disk-like model of spinning electrons is the correct model for electrons. Vyasa’s definition of kshana opens the possibility of a new foundation for the theory of physical time, and perspectives in theoretical and philosophical research. 展开更多
关键词 Natural Time Unit Quantum Time Kshana Plank Time Intrinsic Angular momentum Thin Disc Model Compton Wavelength
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高等教育数字治理:数字化时代的高等教育治理范型 被引量:3
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作者 杜岩岩 牛军明 《江苏高教》 北大核心 2024年第3期53-61,共9页
高等教育数字治理是数字化时代最重要的高等教育治理范型,是数字技术与高等教育治理理论和实践相结合而催生的新型治理范式。数字治理能够对多场景、全过程的高等教育管理数据进行关联、交叉、分析、整合,促进教育治理过程科学化,突破... 高等教育数字治理是数字化时代最重要的高等教育治理范型,是数字技术与高等教育治理理论和实践相结合而催生的新型治理范式。数字治理能够对多场景、全过程的高等教育管理数据进行关联、交叉、分析、整合,促进教育治理过程科学化,突破传统教育治理中“暗箱”问题。学界关于高等教育数字治理的概念阐释主要形成了数据安全论、技术赋能论、场域整合论等三种学术论说,分别从不同的侧面诠释了高等教育数字治理的内涵与特征等。数字治理在提升高等教育治理水平和能力方面至关重要,体现为实现治理主体高效互动、提升循证治理能力和优化精准服务水平等多个方面。同时,高等教育数字治理也有自身的局限性,主要表现为数字安全风险、教育正义危机、数据孤岛、形式化治理、学术求真精神式微等。高等教育数字治理是一项系统工程,需要从强化理性认知、优化治理结构、聚合治理动能、适配治理机制等四个层面重新构建与优化高等教育数字治理生态,实现高等教育数字治理能力的全方位提升。 展开更多
关键词 数字治理 技术嵌入 数字赋能 治理动能
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生态位视角下创新型产业集群竞争力测度研究 被引量:4
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作者 胡雅蓓 夏勇 《统计与信息论坛》 北大核心 2024年第1期30-43,共14页
创新型产业集群是通过聚合创新形成现代产业竞争优势的战略性力量。在生态位理论视角下,构建创新型产业集群竞争力评价的理论分析框架,选取技术、组织、资本、服务创新资源生态位因子,运用生态位宽度、重叠度、适宜度及竞争力综合评价... 创新型产业集群是通过聚合创新形成现代产业竞争优势的战略性力量。在生态位理论视角下,构建创新型产业集群竞争力评价的理论分析框架,选取技术、组织、资本、服务创新资源生态位因子,运用生态位宽度、重叠度、适宜度及竞争力综合评价模型对中国70个创新型产业集群的生态位竞争力进行多维测度。研究发现,中国创新型产业集群的生态位宽度呈递增趋势,涵盖的资源空间日益广泛,资源聚合竞争力逐年增强;生态位重叠度存在过度竞争、过度分散等问题,其中地理位置邻近、主导产业相同的创新集群间生态位重叠度偏高;生态位适宜度总体偏低,进化动量总体较高,说明多数集群在生境适应能力方面的竞争力较弱,与领先集群间差距较大,但呈现出较好的成长性。生态位竞争力综合分析显示,创新集群形成了由四个梯队构成的产业创新空间格局。从产业特征看,新一代信息技术及相关服务业集群的生态位竞争优势明显,而节能环保、高端装备与新能源汽车产业的创新集群则处于生态位竞争劣势;从空间维度看,南部沿海区域的创新集群生态位竞争力最强,形成珠三角经济圈创新生态高地,而大西北区域的创新集群则面临着创新生态脆弱性的挑战,存在更大的进化动量空间。据此,提出资源协同集聚、集群错位竞争和区域协调发展策略以进一步提升中国创新型产业集群的生态位竞争力。 展开更多
关键词 创新型产业集群 生态位宽度 生态位重叠度 生态位适宜度 进化动量 生态位竞争力
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A Review on the Study of Continental Drift and Numerical Simulation Associated with the Early Earth Core-Magma Angular Momentum Exchange
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作者 Weihong Qian 《Open Journal of Geology》 2023年第9期980-1006,共27页
According to the drive of planetary-scale upper magma fluid motions associated with the core-magma angular momentum exchange in the early Earth’s interior, this paper reviewed the results of continental drift studied... According to the drive of planetary-scale upper magma fluid motions associated with the core-magma angular momentum exchange in the early Earth’s interior, this paper reviewed the results of continental drift studied over the last three decades. The theoretical speculation is in good fit to the traces of geological events left on the Earth’s surface. A northeastward drift directionality of the Australian, African, and South American continents relative to the Antarctica Continent in the Southern Hemisphere is reanalyzed according to the slowing down of the early Earth’s rotation. Six traces of significant back-and-forth drifts of the Australian and Asian continents left respectively on the Southwest and Northwest Pacific seafloors are reidentified according to the gradually decreasing amplitude of core-magma angular momentum exchange during early geological evolution. Finally, the thickening and shortening of different continents during the early drift processes are re-simulated by using a simple magma fluid dynamical model. 展开更多
关键词 Continental Drift Driving Force DIRECTIONALITY Numerical Model Angular momentum Exchange
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共生视域下区域数字创新生态系统进化与障碍度研究 被引量:1
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作者 田庆锋 沈伟康 李瑶 《科技进步与对策》 北大核心 2024年第16期1-12,共12页
建设区域数字创新生态系统对提升创新驱动力、实现数字中国具有重要现实意义。从共生视域结合技术进化理论,分析区域数字创新生态系统内涵与进化机制,进而构建评价指标体系,基于2013-2021年省级面板数据,运用共生度、共生进化动量和障... 建设区域数字创新生态系统对提升创新驱动力、实现数字中国具有重要现实意义。从共生视域结合技术进化理论,分析区域数字创新生态系统内涵与进化机制,进而构建评价指标体系,基于2013-2021年省级面板数据,运用共生度、共生进化动量和障碍因子诊断分析模型等探究区域数字创新生态系统进化过程及障碍度。结果表明:①我国区域数字创新生态系统共生度整体呈现上升趋势,但地区差异显著;②共生进化呈现良好发展态势,但也存在明显的区域“马太效应”,总体进化动量非均衡性波动减小,区域不均衡是造成总体进化动量不均衡的主要来源,进化动量轨迹由初、中级水平转向中高、高级水平;③区域共生基质是制约共生进化的主要障碍因子,其数字技术发展平均障碍度为37.47%,是影响数字创新生态系统发展的关键。 展开更多
关键词 区域数字创新生态系统 共生度 共生进化动量 障碍因子诊断
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顾及有效角动量与IGS超快解数据的极移预报方法
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作者 魏娜 周雨欣 +3 位作者 许雪晴 楼益栋 戴小蕾 施闯 《地球物理学报》 SCIE EI CAS CSCD 北大核心 2024年第4期1356-1367,共12页
极移高精度预报对卫星实时定轨、深空探测器导航等应用至关重要.本文提出了一种联合有效角动量(Effective Angular Momentum,EAM)与国际全球卫星导航系统服务组织(International GNSS Service,IGS)提供的超快解数据进行极移预报的方法.... 极移高精度预报对卫星实时定轨、深空探测器导航等应用至关重要.本文提出了一种联合有效角动量(Effective Angular Momentum,EAM)与国际全球卫星导航系统服务组织(International GNSS Service,IGS)提供的超快解数据进行极移预报的方法.该方法基于IGS超快解数据得到的极移第1天预报值,对引入EAM得到的极移预报结果进行校正,获得联合预报值.首先,基于LS(Least Squares)+AR(Auto-Regressive)模型实现了引入EAM的极移预报,相对国际地球自转与参考系统服务组织(International Earth Rotation and Reference Systems Service,IERS)提供的公报A数据,在超短期(第1~10天)预报跨度可以得到更高精度的极移预报结果,其中大气和海洋角动量发挥了主要作用.其次,鉴于IGS超快解数据精度高、更新快的特点,以IGS超快解为基础数据,基于LS+AR模型可以得到极移第1天预报值,其精度显著优于IERS公报A的极移第1天预报值.最后,利用第1天预报值对顾及有效角动量的预报结果进行校正获得了联合预报值,进一步提高了超短期极移预报精度(尤其是第1~5天).2020年7月24日—2022年1月30日间的联合预报结果表明:第1~20天的预报值总体优于IERS公报A的预报值.其中,第1~10天的预报精度显著提升,在预报第1天,X、Y方向预报值相对公报A预报值的精度提升分别可达39.5%~62.3%和24.5%~51.9%;在预报第10天,相对公报A预报值的精度提升分别可达28.0%~28.9%和21.9%~23.4%. 展开更多
关键词 极移预报 有效角动量 IGS极移超快解 LS+AR模型
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Meissner Exclusion of Gravito-Magnetic Energy from a Momentum-Space Crystal
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作者 Edwin Eugene Klingman 《Journal of Modern Physics》 2023年第S1期1721-1734,共14页
A primordial field theory of Quantum Gravity resolves a number of century-old paradoxes associated with general relativity and quantum mechanics. It allows re-interpretation of major experiments such as Michelson-Gale... A primordial field theory of Quantum Gravity resolves a number of century-old paradoxes associated with general relativity and quantum mechanics. It allows re-interpretation of major experiments such as Michelson-Gale (1925) and Q-bounce (1999). I address herein an unexplained anomalous experiment by Martin Tajmar (2006), in terms of a gravitomagnetic-based Meissner effect. 展开更多
关键词 Quantum Gravity Meissner Exclusion momentum Space Crystal GRAVITOMAGNETISM Tajmar Anomaly
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Magnetic Charge Theory Part 4: Fermion Angular Momentum
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作者 Keith G. Lyon 《Journal of Modern Physics》 2023年第10期1305-1309,共5页
The magnetic charge concept is further developed to define the vibrational motion of a charged particle moving in the ether/dark matter. The angular momentum of the resulting motion is derived to be ħ/2 at all velocit... The magnetic charge concept is further developed to define the vibrational motion of a charged particle moving in the ether/dark matter. The angular momentum of the resulting motion is derived to be ħ/2 at all velocities. The vibrational motion also provides additional justification for the Coulomb and gravitational forces not having a singularity. Additional insights into antimatter composition and annihilation are also developed. 展开更多
关键词 Particle Spin ANTIMATTER Particle Vibration Particle Angular momentum Magnetic Charge Dark Matter ETHER
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一种适应卫星姿态侧摆机动的混合轮系控制方法
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作者 雷拥军 陆栋宁 +1 位作者 袁利 陈超 《中国空间科学技术(中英文)》 CSCD 北大核心 2024年第3期111-119,共9页
针对高稳定度轮控大型卫星因动量轮力矩小而难以满足侧摆成像任务需求问题,开展了混合轮系配置方案及控制方法研究。首先,提出常规轮系配置卫星滚动轴方向串联大力矩飞轮的混合配置方案,并设计飞轮开环前馈与常规动量轮闭环反馈相结合... 针对高稳定度轮控大型卫星因动量轮力矩小而难以满足侧摆成像任务需求问题,开展了混合轮系配置方案及控制方法研究。首先,提出常规轮系配置卫星滚动轴方向串联大力矩飞轮的混合配置方案,并设计飞轮开环前馈与常规动量轮闭环反馈相结合的控制策略;其次,设计以容许角动量最大量为权重的飞轮组前馈力矩分配律和具有角动量反馈的飞轮力矩跟踪控制方法,实现飞轮力矩合理分配及其模型不确定性导致输出力矩偏差抑制;然后,设计估计器对星体内外扰动力矩进行估计与补偿,以确保卫星高稳定度性能实现;最后,给出在轨应用情况,验证所提出方案及方法的有效性。在轨应用表明,采用该控制方法,有效缩短了整星侧摆稳定时间达100 s以上,且非机动期间姿态稳定度优于3.75×10-5(°)/s。 展开更多
关键词 姿态控制 混合轮系配置 前馈控制 动量轮 大力矩飞轮
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“三治融合”何以赋能农村集体公益设施建设和管护——基于内生动力的视角 被引量:1
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作者 许军 白欣宇 《安徽乡村振兴研究》 2024年第1期47-58,共12页
内生动力不足是困扰农村集体公益设施建设和管护的重要因素。文章以西安市长安区四皓村美丽乡村建设为例,分析“三治融合”如何激发内生动力进而赋能农村集体公益设施建设和管护:首先,“三治融合”构成的农村“现代公共规则”与农村发... 内生动力不足是困扰农村集体公益设施建设和管护的重要因素。文章以西安市长安区四皓村美丽乡村建设为例,分析“三治融合”如何激发内生动力进而赋能农村集体公益设施建设和管护:首先,“三治融合”构成的农村“现代公共规则”与农村发展内生动力中的认同、参与、资源等基本要素相嵌合;其次,以党组织为核心的组织机构,通过“三治融合”的治理模式,形成内外部力量的有效互动,构建不同价值的双重循环,搭建个体与集体间的利益关联,产生农村集体公益设施建设和管护中的内驱力;最后,乡村公共事务治理不能仅依赖外部力量的介入,内外力量的互动是农村发展过程中内生动力生成的逻辑前提,构建村民个体与村社共同体的关联和认同是关键。 展开更多
关键词 农村集体公益设施 三治融合 内生动力
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Principal Role of Angular Momentum in Cosmology
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作者 Vladimir S. Netchitailo 《Journal of High Energy Physics, Gravitation and Cosmology》 2023年第4期984-1003,共20页
According to “Evolution Encyclopedia” (The Origin of the Solar System), “There is no possible means by which the angular momentum from the sun could be transferred to the planets”. Yet this is what would have to b... According to “Evolution Encyclopedia” (The Origin of the Solar System), “There is no possible means by which the angular momentum from the sun could be transferred to the planets”. Yet this is what would have to be done if any of the evolutionary theories of solar system origin are to be accepted. Scientists cannot account for this puzzling situation: less than one percent of the mass of the solar system is in the planets, while a staggering 98 percent of its angular momentum is in them. It simply does not fit into any of the cosmologies. Speaking of the mass-angular momentum problem, D. Bergamini says: “A theory of evolution that fails to account for this peculiar fact is ruled out before it starts” [1]. Angular Momentum problem is one of the most critical problems in Standard model that must be solved. To the best of our knowledge, the developed Hypersphere World-Universe Model (WUM) is only cosmological model in existence that is consistent with the Law of Conservation of Angular Momentum [2]. In the present paper, we discuss Angular Momenta of Solar System, Milky Way galaxy, and Superclusters in frames of WUM. 展开更多
关键词 Angular momentum Rotational Fission Multicomponent Dark Matter Macroobject Shell Model Macroobjects Formation Solar System Milky Way SUPERCLUSTERS
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波流共同作用下射流稀释特性的动量积分模拟研究
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作者 陈永平 李醒非 +3 位作者 方树桥 徐振山 陈雨航 Ebenezer Otoo 《海洋学报》 CAS CSCD 北大核心 2024年第2期1-13,共13页
污水通常以射流的形式向海排放,其在海洋环境水体中的稀释过程是射流与波浪、潮流共同作用的结果。本文基于合理的假设条件,对射流运动的控制方程进行积分处理,结合波流环境下射流的结构特征,引入射流卷吸与拖曳力函数,结合必要的边界条... 污水通常以射流的形式向海排放,其在海洋环境水体中的稀释过程是射流与波浪、潮流共同作用的结果。本文基于合理的假设条件,对射流运动的控制方程进行积分处理,结合波流环境下射流的结构特征,引入射流卷吸与拖曳力函数,结合必要的边界条件,形成封闭的控制方程组,建立波流环境下射流动量积分模型。通过与实验资料的对比分析可以看出,该模型可以准确模拟波流环境下射流在近区段的时均运动与稀释过程;相较于单一的横流作用,波流共同作用下射流对周边水体的影响范围更大,射流初始稀释能力更强。基于多个组次的动量积分模拟实验,通过无量纲分析与最小二乘拟合,建立了波流共同作用下射流轨迹中心线位置及最小稀释度的经验公式。相关成果可为排海污水环境影响评估提供快速、准确的分析手段。 展开更多
关键词 波流环境 射流 动量积分模拟 射流轨迹 稀释度
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高阶轨道角动量传输光纤设计及传输特性研究(内封底文章)
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作者 赵丽娟 吴雨静 徐志钮 《红外与激光工程》 EI CSCD 北大核心 2024年第3期162-174,共13页
为解决一般轨道角动量传输光纤传输轨道角动量模式数量少、质量差的问题,提出了一种基于正六边形空气孔排列的新型光子晶体光纤结构。该光纤引入了空气填充率高的矩形空气孔以及采用高折射率材料填充环形传输区域,能够有效提高环形传输... 为解决一般轨道角动量传输光纤传输轨道角动量模式数量少、质量差的问题,提出了一种基于正六边形空气孔排列的新型光子晶体光纤结构。该光纤引入了空气填充率高的矩形空气孔以及采用高折射率材料填充环形传输区域,能够有效提高环形传输区域和包层间的折射率差,且正六边形排列空气孔有利于提高模间有效折射率差。经过结构优化得到最优光纤结构,有限元法的分析结果表明,最优结构下,该光纤在常用波段S+C+L+U波段上能够支持142种轨道角动量模式的传输,最高阶数达到36阶。且所提出光纤具有良好的传输特性,本征模式的最高限制性损耗为10−9 dB/m量级,与典型轨道角动量传输光子晶体光纤相比至少降低了一个数量级;最大有效模场面积能够达到206.18μm^(2),最小非线性系数低至0.397 W^(−1)∙km^(−1);色散平坦且最小色散变化低至1.4578 ps/(nm∙km);所有本征模式纯度均在93.4%~96.8%范围内。且该光纤具有较好的制备可行性,对制造精度要求不高。因此,该光纤在基于轨道角动量光纤的复用系统中具有广阔的应用前景,为提高通信容量提供了一种有效手段。 展开更多
关键词 光纤光学 轨道角动量 有限元法 限制性损耗 通信容量
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外商投资区域生态位、进化动量与空间分布——2012—2021年中国31个省份实证研究
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作者 丁玲 韩家平 +1 位作者 苏玲 李文琦 《国际贸易》 北大核心 2024年第4期72-86,共15页
战略定位是战略管理的核心,区域生态位是战略定位的核心。文章将区域生态位视角引入外商投资领域,以2012—2021年外商投资中国内地31个省份为研究对象,探索外商投资区域生态位、进化动量和空间分布规律。研究结果表明:(1)外商投资中国... 战略定位是战略管理的核心,区域生态位是战略定位的核心。文章将区域生态位视角引入外商投资领域,以2012—2021年外商投资中国内地31个省份为研究对象,探索外商投资区域生态位、进化动量和空间分布规律。研究结果表明:(1)外商投资中国资源竞争不激烈,区域生态位强度、重叠度不高,生态位宽度较大,外商投资沿海地区较多、大西北地区较少;(2)外商投资中国区域生态位强度和宽度的进化动量较大、外商投资提升空间较大,在大西北地区提升空间较大、沿海地区提升空间较小;(3)中国外商投资空间呈现梯队分布且地理空间呈现高高聚集或低低聚集的正相关关系;(4)外商投资中国区域生态位强度、宽度及强度进化动量对于外贸区域发展具有促进作用,生态位宽度进化动量对区域外贸发展促进作用不明显。由此,文章分析得出如下启示:我国宜促进外商投资区域资源扩展和进化程度、优化外商投资区域资源结构和进化动能、强化外商投资区域协同和产业聚集效应。 展开更多
关键词 区域生态位 进化动量 外商投资 战略管理 开放经济
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基于OAM复用信号高效调制解调的声学超表面
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作者 刘智 黄保霖 +1 位作者 林玮 赵瑾瑜 《南京大学学报(自然科学版)》 CAS CSCD 北大核心 2024年第2期339-344,共6页
轨道角动量(Orbital Angular Momentum,OAM)复用是提高声学通信系统数据容量的一种潜在解决方案,提出一种利用声学超表面对OAM复用信号进行调制和解调的方法,利用该方法对独立声轨道角动量(Acoustic Orbital Angular Momentum,AOAM)信... 轨道角动量(Orbital Angular Momentum,OAM)复用是提高声学通信系统数据容量的一种潜在解决方案,提出一种利用声学超表面对OAM复用信号进行调制和解调的方法,利用该方法对独立声轨道角动量(Acoustic Orbital Angular Momentum,AOAM)信号的幅度和相位进行分析,并通过仿真实现对AOAM信号的调制和解调.AOAM信号的相位和幅度提供正交自由度,通过设计合适的声学超表面并将其与二进制差分相位编码技术相结合,证明其可以实现AOAM复用信号的有效调制和解调.正交声学螺旋模态可防止模式耦合和串扰,从而增强声学多路复用.基于谐振的结构提供信号频率选择性,提高了交互效率,简化了终端设备,便于实现大容量声学通信系统的创建. 展开更多
关键词 声学超表面 声轨道角动量 声信号复用
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