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参数化S谱幅值调制及轴承故障诊断应用
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作者 姜祖华 张坤 +1 位作者 杨欢 胥永刚 《西安交通大学学报》 EI CAS CSCD 北大核心 2024年第3期117-128,共12页
针对传统谱幅值调制方法易受噪声影响的问题,利用参数化S变换得到信号在时频域中的幅值,提出了一种参数化S谱幅值调制方法。该方法首先使用参数化S变换将信号转换到时频域并得到幅值和相位,然后将不同权重赋予时频域中的幅值以改变不同... 针对传统谱幅值调制方法易受噪声影响的问题,利用参数化S变换得到信号在时频域中的幅值,提出了一种参数化S谱幅值调制方法。该方法首先使用参数化S变换将信号转换到时频域并得到幅值和相位,然后将不同权重赋予时频域中的幅值以改变不同能量频率成分在信号中的占比,最后将调制后的幅值与原相位结合,使用参数化S逆变换重构一系列修正信号并计算其平方包络谱以提取故障特征。仿真和实验结果表明,该方法获得的幅值信息相比传统谱幅值调制方法更加准确和全面,对强噪声环境更具鲁棒性,能够有效实现滚动轴承的外圈、内圈和复合故障诊断。将所提方法与传统谱幅值调制方法和快速谱峭度方法进行对比,证明了参数化S谱幅值调制既能检测强噪声环境下的轴承故障信息,又能同时提取多种故障分量,在滚动轴承的故障特征提取中更具优越性。 展开更多
关键词 滚动轴承 故障诊断 谱幅值调制 参数化s谱幅值调制
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The Tension Cosmology, Largest Cosmic Structures and Explosions of Supernovae from SST
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作者 Sylwester Kornowski 《Journal of High Energy Physics, Gravitation and Cosmology》 CAS 2024年第3期1029-1044,共16页
Here, using the Scale-Symmetric Theory (SST) we explain the cosmological tension and the origin of the largest cosmic structures. We show that a change in value of strong coupling constant for cold baryonic matter lea... Here, using the Scale-Symmetric Theory (SST) we explain the cosmological tension and the origin of the largest cosmic structures. We show that a change in value of strong coupling constant for cold baryonic matter leads to the disagreement in the galaxy clustering amplitude, quantified by the parameter S8. Within the same model we described the Hubble tension. We described also the mechanism that transforms the gravitational collapse into an explosion—it concerns the dynamics of virtual fields that lead to dark energy. Our calculations concern the Type Ia supernovae and the core-collapse supernovae. We calculated the quantized masses of the progenitors of supernovae, emitted total energy during explosion, and we calculated how much of the released energy was transferred to neutrinos. Value of the speed of sound in the strongly interacting matter measured at the LHC confirms that presented here model is correct. Our calculations show that the Universe is cyclic. 展开更多
关键词 scale-symmetric Theory Tension Cosmology Coupling Constants parameters σ8 and s8 Largest Cosmic structures Dark Energy supernova Explosion Cyclic Universe
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A Simple Mechanism for Generating a Geomagnetic Field
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作者 Oleg Vladimirovich Styazhkin 《Open Journal of Applied Sciences》 2024年第9期2580-2591,共12页
On the basis of the ideal gas model, the polarization of charges in the mantle was obtained, a physical and mathematical model was constructed, and estimated calculations of the dipole mode of the Earth’s magnetic fi... On the basis of the ideal gas model, the polarization of charges in the mantle was obtained, a physical and mathematical model was constructed, and estimated calculations of the dipole mode of the Earth’s magnetic field were performed, taking into account the speed of its angular rotation, the parameters of density and temperature, the chemical composition, the ionization potential, the dielectric constant and the percentage of the main chemical compounds of the mantle substance. 展开更多
关键词 Physical parameters of the Earth’s Mantle Maxwell-Boltzmann statistics Phonon Gas Thermal Ionization Electron-Hole Polarization Electron-Hole Recombination Earth’s Magnetic Field Dipole Mode of the Magnetic Field
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Research on COB De-embedding in Scattering Parameter Measurement
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作者 Lei Wang Jingyi Zhang 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2017年第1期37-42,共6页
The popular radio frequency(RF) chip on board(COB) test has gradually taken the place of onwafer test due to the high efficiency and high power. This paper presents the extended Open-Short-Load(OSL) that is one-port c... The popular radio frequency(RF) chip on board(COB) test has gradually taken the place of onwafer test due to the high efficiency and high power. This paper presents the extended Open-Short-Load(OSL) that is one-port calibration method to verify the error model de-embedding in S parameter measurement. Threelevel cascade structure on COB's system error model is proposed and analyzed. Four kinds of calibration plane solutions for de-embedding are verified. At last,on-board calibration(CAL) kits solution is established to decrease the system error to the least value. The maximum error shift can be controlled less than 0.1 dB comparing with the on-wafer test results. In general,the practical application results prove that this method is reasonable and effective and easy to be mastered. 展开更多
关键词 s parameter COB DE-EMBEDDING
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Dynamics and adaptive control of a dual-arm space robot with closed-loop constraints and uncertain inertial parameters 被引量:20
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作者 Ying-Hong Jia Quan Hu Shi-Jie Xu 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2014年第1期112-124,共13页
A dynamics-based adaptive control approach is proposed for a planar dual-arm space robot in the presence of closed-loop constraints and uncertain inertial parameters of the payload. The controller is capable of contro... A dynamics-based adaptive control approach is proposed for a planar dual-arm space robot in the presence of closed-loop constraints and uncertain inertial parameters of the payload. The controller is capable of controlling the po- sition and attitude of both the satellite base and the payload grasped by the manipulator end effectors. The equations of motion in reduced-order form for the constrained system are derived by incorporating the constraint equations in terms of accelerations into Kane's equations of the unconstrained system. Model analysis shows that the resulting equations perfectly meet the requirement of adaptive controller design. Consequently, by using an indirect approach, an adaptive control scheme is proposed to accomplish position/attitude trajectory tracking control with the uncertain parameters be- ing estimated on-line. The actuator redundancy due to the closed-loop constraints is utilized to minimize a weighted norm of the joint torques. Global asymptotic stability is proven by using Lyapunov's method, and simulation results are also presented to demonstrate the effectiveness of the proposed approach. 展开更多
关键词 space robot Dynamics. Adaptive control Closed-loop constraint parameter uncertainty - Kane's equation
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s-parameterized Weyl transformation and the corresponding quantization scheme 被引量:2
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作者 王继锁 孟祥国 范洪义 《Chinese Physics B》 SCIE EI CAS CSCD 2015年第1期265-268,共4页
By extending the usual Weyl transformation to the s-parameterized Weyl transformation with s being a real parameter,we obtain the s-parameterized quantization scheme which includes P–Q quantization, Q–P quantization... By extending the usual Weyl transformation to the s-parameterized Weyl transformation with s being a real parameter,we obtain the s-parameterized quantization scheme which includes P–Q quantization, Q–P quantization, and Weyl ordering as its three special cases. Some operator identities can be derived directly by virtue of the s-parameterized quantization scheme. 展开更多
关键词 generalized Wigner transformation s-parameterized quantization scheme
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S Phase Cell Percentage Normalized BrdU Incorporation Rate, a New Parameter for Determining S Arrest 被引量:2
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作者 ZHAO Peng FU Juan Ling +2 位作者 YAO Bi Yun JIA Yong Rui ZHOU Zong Can 《Biomedical and Environmental Sciences》 SCIE CAS CSCD 2014年第3期215-219,共5页
In this study, a new parameter, S phase cell percentage (S fraction) normalized BrdU (SFN-BrdU) incorporation rate, was introduced to detect $ arrest. The results showed a positive linear correlation between the B... In this study, a new parameter, S phase cell percentage (S fraction) normalized BrdU (SFN-BrdU) incorporation rate, was introduced to detect $ arrest. The results showed a positive linear correlation between the BrdU incorporation rate and the S fraction in unperturbed 16HBE cells. Theoretical analysis indicated that only S arrest could result in a decrease in the SFN-BrdU incorporation rate. Additionally, the decrease in SFN-BrdU incorporation rate and the activation of DNA damage checkpoints further demonstrated that S arrest was induced by diethyl sulfate treatment of 16HBE cells. In conclusion, $FN-BrdU incorporation rate can be used to detecting S arrest. 展开更多
关键词 BRDU RATE s Phase Cell Percentage Normalized BrdU Incorporation Rate a New parameter for Determining s Arrest
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The s-parameterized Weyl-Wigner correspondence in the entangled form and its applications
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作者 范洪义 胡利云 袁洪春 《Chinese Physics B》 SCIE EI CAS CSCD 2010年第6期52-57,共6页
Based on the theory of integration within s-ordering of operators and the bipartite entangled state representation we introduce s-parameterized Weyl-Wigner correspondence in the entangled form. Some of its application... Based on the theory of integration within s-ordering of operators and the bipartite entangled state representation we introduce s-parameterized Weyl-Wigner correspondence in the entangled form. Some of its applications in quantum optics theory are presented as well. 展开更多
关键词 s-parameterized Wigner operator s-parameterized Weyl-Wigner correspondence integration within s-ordered product of operators technique
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改进YOLOX-S模型的施工场景目标检测 被引量:11
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作者 胡皓 郭放 刘钊 《计算机科学与探索》 CSCD 北大核心 2023年第5期1089-1101,共13页
现有YOLOX-S模型在施工环境干扰下目标检测平均精准率(AP)偏低,不能较好满足实际应用需要。针对上述问题,从引入结构重参数化模块、引入卷积注意力模块、引入AdamW优化算法三方面对YOLOX-S模型进行改进。首先,利用RepVGGBlock解耦训练... 现有YOLOX-S模型在施工环境干扰下目标检测平均精准率(AP)偏低,不能较好满足实际应用需要。针对上述问题,从引入结构重参数化模块、引入卷积注意力模块、引入AdamW优化算法三方面对YOLOX-S模型进行改进。首先,利用RepVGGBlock解耦训练阶段与测试阶段的模型结构,在训练阶段模型的Backbone与Neck中构建更多残差结构,提高模型的特征提取能力。其次,利用LKA模块提取局部特征信息与长距离依赖关系,为后续计算目标边界框位置与大小提供更加有效的注意力指引,提升检测平均精准率。然后,使用AdamW优化算法替代Adam优化算法更新模型参数,进一步改良模型收敛结果,提升模型泛化能力。最后,在建筑工地运动目标数据集(MOCS)上进行实验,结果表明,改进YOLOX-S模型检测所有目标的平均精准率提升3.3个百分点,检测大目标、中目标、小目标的平均精准率分别提升3.2、2.3、2.2个百分点。同时,改进YOLOX-S模型计算代价未明显增加,可在实时运行的同时更好满足施工场景下对目标检测平均精准率的需要。 展开更多
关键词 目标检测 施工场景 结构重参数化 大核注意力 YOLOX-s
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An Efficient Accurate Direct Solution of Poisson's Equation for Computation of Meteorological Parameters
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作者 D.R.Chakraborty P.S.Salvekar 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 1989年第4期501-508,共8页
Poisson's equation is solved numerically by two direct methods, viz. Block Cyclic Reduction (BCR) method and Fourier Method. Qualitative and quantitative comparison between the numerical solutions obtained by two ... Poisson's equation is solved numerically by two direct methods, viz. Block Cyclic Reduction (BCR) method and Fourier Method. Qualitative and quantitative comparison between the numerical solutions obtained by two methods indicates that BCR method is superior to Fourier method in terms of speed and accuracy. Therefore. BCR method is applied to solve (?)2(?)= ζ and (?)2X= D from observed vorticity and divergent values. Thereafter the rotational and divergent components of the horizontal monsoon wind in the lower troposphere are reconstructed and are com pared with the results obtained by Successive Over-Relaxation (SOR) method as this indirect method is generally in more use for obtaining the streamfunction ((?)) and velocity potential (X) fields in NWP models. It is found that the results of BCR method are more reliable than SOR method. 展开更多
关键词 An Efficient Accurate Direct solution of Poisson’s Equation for Computation of Meteorological parameters
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Need for multiple biomarkers to adjust parameters of closed-loop deep brain stimulation for Parkinson's disease
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作者 Takashi Morishita Tooru Inoue 《Neural Regeneration Research》 SCIE CAS CSCD 2017年第5期747-748,共2页
Closed-loop deep brain stimulation(DBS):DBS has been established as a surgical therapy for movement disorders and select neuropsychiatric disorders.Various efforts to improve the clinical outcomes of the procedure ... Closed-loop deep brain stimulation(DBS):DBS has been established as a surgical therapy for movement disorders and select neuropsychiatric disorders.Various efforts to improve the clinical outcomes of the procedure have been previously made.Several factors affect the DBS clinical outcomes such as lead position,programming technique, 展开更多
关键词 DBs Need for multiple biomarkers to adjust parameters of closed-loop deep brain stimulation for Parkinson’s disease deep
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Searching the Parameters of Dark Matter Halos on the Basis of Dwarf Galaxies’ Dynamics
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作者 L. M. Chechin T. K. Konysbayev 《Journal of Modern Physics》 2016年第9期982-988,共7页
Article devoted to searching the parameters of dark matter halos on the base of dwarf galaxies’ dynamics (Messier 32 and Leo I). For doing this, we propose the new approach founded on construction the coupled ellipti... Article devoted to searching the parameters of dark matter halos on the base of dwarf galaxies’ dynamics (Messier 32 and Leo I). For doing this, we propose the new approach founded on construction the coupled elliptical trajectory for a probe body in the gravitational fields of Newtonian potential and potential of dark matter’s halo. This allows more accuracy estimate its central density for the Navarro-Frenk-White profile and free parameter for the Einasto profile . Our result is in good correlation with results of other authors that are got by different numerical methods. 展开更多
关键词 Dwarf Galaxies Dark Matter Halo Central Density of Dark Matter Profile parameters of Dark Matter’s Halo
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On the Cosmic Evolution of the Quantum Vacuum Using Two Variable G Models and Winterberg’s Thesis
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作者 Christopher Pilot 《Journal of High Energy Physics, Gravitation and Cosmology》 2023年第4期1134-1160,共27页
We work within a Winterberg framework where space, i.e., the vacuum, consists of a two component superfluid/super-solid made up of a vast assembly (sea) of positive and negative mass Planck particles, called planckion... We work within a Winterberg framework where space, i.e., the vacuum, consists of a two component superfluid/super-solid made up of a vast assembly (sea) of positive and negative mass Planck particles, called planckions. These material particles interact indirectly, and have very strong restoring forces keeping them a finite distance apart from each other within their respective species. Because of their mass compensating effect, the vacuum appears massless, charge-less, without pressure, net energy density or entropy. In addition, we consider two varying G models, where G, is Newton’s constant, and G<sup>-1</sup>, increases with an increase in cosmological time. We argue that there are at least two competing models for the quantum vacuum within such a framework. The first follows a strict extension of Winterberg’s model. This leads to nonsensible results, if G increases, going back in cosmological time, as the length scale inherent in such a model will not scale properly. The second model introduces a different length scale, which does scale properly, but keeps the mass of the Planck particle as, ± the Planck mass. Moreover we establish a connection between ordinary matter, dark matter, and dark energy, where all three mass densities within the Friedman equation must be interpreted as residual vacuum energies, which only surface, once aggregate matter has formed, at relatively low CMB temperatures. The symmetry of the vacuum will be shown to be broken, because of the different scaling laws, beginning with the formation of elementary particles. Much like waves on an ocean where positive and negative planckion mass densities effectively cancel each other out and form a zero vacuum energy density/zero vacuum pressure surface, these positive mass densities are very small perturbations (anomalies) about the mean. This greatly alleviates, i.e., minimizes the cosmological constant problem, a long standing problem associated with the vacuum. 展开更多
关键词 Winterberg Model Planck Particles Positive and Negative Mass Planck Particles Planckions Quantum Vacuum space as a superfluid/supersolid Extended Models for space Cosmological Constant Higgs Field as a Composite Particle Higgs Boson Inherent Length scale for the Vacuum Dark Energy Cosmological scaling Behavior for the Quantum Vacuum Variable G Models Extended Gravity Newton’s Constant as an Order parameter High Energy Behavior for the Vacuum
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基于ASP技术的数控磨床参数化建模实现 被引量:2
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作者 蔡长韬 许明恒 +1 位作者 陈守强 李海庆 《计算机工程》 EI CAS CSCD 北大核心 2005年第12期202-204,共3页
提出了基于B/S三层模式的中间件解决方案,利用ASP技术,在网页中调用自制组建,实现对数控磨床的参数化设计,在网上在线生成数控磨床的三维模型,充分利用异地分布的设计资源,在有效的协同工作机制和支撑平台工具下统一信息管理,共同完成... 提出了基于B/S三层模式的中间件解决方案,利用ASP技术,在网页中调用自制组建,实现对数控磨床的参数化设计,在网上在线生成数控磨床的三维模型,充分利用异地分布的设计资源,在有效的协同工作机制和支撑平台工具下统一信息管理,共同完成机械零件的设计开发。 展开更多
关键词 AsP技术 B/s模式 参数化设计
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Artificial network prediction on degradable properties of coal-filled films 被引量:2
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作者 杨志远 周安宁 曲建林 《Journal of Coal Science & Engineering(China)》 2005年第2期78-81,共4页
Utilized degradable data of coal-filled films from the accelerated UV chamber ageing degradation experiments, and on the basis of control factors’ analysis, presented a predicting model on degradable properties of th... Utilized degradable data of coal-filled films from the accelerated UV chamber ageing degradation experiments, and on the basis of control factors’ analysis, presented a predicting model on degradable properties of this film in photo-degradation according to back-propagation artificial neural network (BP ANN). 4 controlling factors in films degrada-tion, including temperature, the time of UV irradiation, the concentration and the type of coals were used as input parameters in the ANN model. While the degradable properties after film degradation, including the mechanical properties and carbonyl index, were used as output parameters. It was carried out by the neural network toolbox of Matlab 6.5 soft-ware and Visual Basic 6.0. Discussed partition of sample data and model’s parameters, and then selected the best configuration of ANN network. The accurate scope of predicting results was analyzed. This model has a high precision in predicting on properties of the coal-filled film degradation. 展开更多
关键词 coal-filled film degradable properties model's parameters ANN PREDICTION
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三层C/S模式在UG/Open开发中的应用研究 被引量:1
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作者 张博林 黄勇 宋传斌 《制造技术与机床》 CSCD 北大核心 2010年第5期63-66,共4页
通过分析UG/Open开发过程中的不足,引入了C/S模式的开发思想,总结出了C/S模式在UG/Open开发中的应用方法,并以渐开线直齿轮库建立为例,阐述了在UG中应用UG/Open参数化设计思想建立齿轮库的一般步骤。同时,通过COM组件技术将三层C/S模式... 通过分析UG/Open开发过程中的不足,引入了C/S模式的开发思想,总结出了C/S模式在UG/Open开发中的应用方法,并以渐开线直齿轮库建立为例,阐述了在UG中应用UG/Open参数化设计思想建立齿轮库的一般步骤。同时,通过COM组件技术将三层C/S模式应用到UG/Open中,实现了UG/Open、MFC、COM和三层C/S模式相结合的应用开发,为在UG平台上进行CAD系统开发提供了数据库的支持。此外,可为其它CAD系统的开发提供参考。 展开更多
关键词 UG/OPEN C/s模式 MFC COM 参数化设计 渐开线 直齿轮库
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Hypersphere World-Universe Model 被引量:3
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作者 Vladimir S. Netchitailo 《Journal of High Energy Physics, Gravitation and Cosmology》 2021年第2期915-941,共27页
Dirac’s themes were the unity and beauty of Nature. He identified three revolutions in modern physics: Relativity, Quantum Mechanics and Cosmology. In his opinion: “<i>The new cosmology will probably turn out ... Dirac’s themes were the unity and beauty of Nature. He identified three revolutions in modern physics: Relativity, Quantum Mechanics and Cosmology. In his opinion: “<i>The new cosmology will probably turn out to be philosophically even more revolutionary than relativity or the quantum theory, perhaps looking forward to the current bonanza in cosmology, where precise observations on some of the most distant objects in the universe are shedding light on the nature of reality, on the nature of matter and on the most advanced quantum theories</i>” [Farmelo, G. (2009) The Strangest Man. The Hidden Life of Paul Dirac, Mystic of the Atom. Basic Books, Britain, 661 p]. In 1937, Paul Dirac proposed the Large Number Hypothesis and the Hypothesis of the variable gravitational “constant”;and later added the notion of continuous creation of Matter in the World. The developed Hypersphere World-Universe Model (WUM) follows these ideas, albeit introducing a different mechanism of matter creation. In this paper, we show that WUM is a natural continuation of Classical Physics and it can already serve as a basis for a New Cosmology proposed by Paul Dirac. 展开更多
关键词 Hypersphere World-Universe Model Law of Conservation of Angular Momentum Dark Epoch Rotational Fission Luminous Epoch Dark Matter Particles Macroobject shell Model Dark Matter Core Medium of the World Dark Matter Fermi Bubbles Galactic Wind solar Wind Gravitational Bursts Intergalactic Plasma Macroobjects supremacy of Matter Gravitomagnetic parameter Impedance Energy Density Gravitational parameter Hubble’s parameter Temperature of Microwave Background Radiation Inter-Connectivity of Primary Cosmological parameters Dark Matter Reactor
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Hypersphere World-Universe Model: Evolution of the World 被引量:2
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作者 Vladimir S. Netchitailo 《Journal of High Energy Physics, Gravitation and Cosmology》 2021年第2期508-530,共23页
The main objective of this paper is to discuss the Evolution of a 3D Finite World (that is a Hypersphere of a 4D Nucleus of the World) from the Beginning up to the present Epoch in frames of World-Universe Model (WUM)... The main objective of this paper is to discuss the Evolution of a 3D Finite World (that is a Hypersphere of a 4D Nucleus of the World) from the Beginning up to the present Epoch in frames of World-Universe Model (WUM). WUM is the only cosmological model in existence that is consistent with the Law of Conservation of Angular Momentum. To be consistent with this Fundamental Law, WUM introduces Dark Epoch (spanning from the Beginning of the World for 0.45 billion years) when only Dark Matter (DM) Macroobjects (MOs) existed, and Luminous Epoch (ever since for 13.77 billion years) when Luminous MOs emerged due to Rotational Fission of Overspinning DM Superclusters’ Cores and self-annihilation of Dark Matter Particles (DMPs). WUM envisions that DM is created by the Universe in the 4D Nucleus of the World. Dark Matter Particles (DMPs) carry new DM into the 3D Hypersphere World. Luminous Matter is a byproduct of DMPs self-annihilation. By analogy with 3D ball, which has two-dimensional sphere surface (that has surface energy), we can imagine that the 3D Hypersphere World has a “Surface Energy” of the 4D Nucleus. WUM solves a number of physical problems in contemporary Cosmology and Astrophysics through DMPs and their interactions: <b>Angular Momentum problem</b> in birth and subsequent evolution of Galaxies and Extrasolar systems—how do they obtain it;<b>Fermi Bubbles</b>—two large structures in gamma-rays and X-rays above and below Galactic center;<b>Missing Baryon problem</b> related to the fact that the observed amount of baryonic matter did not match theoretical predictions. WUM reveals <b>Inter-Connectivity of Primary Cosmological Parameters</b> and calculates their values, which are in good agreement with the latest results of their measurements. In 2013, WUM predicted the values of the following Cosmological parameters: gravitational, concentration of intergalactic plasma, and the minimum energy of photons, which were experimentally confirmed in 2015-2018. “<i>The Discovery of a Supermassive Compact Object at the Centre of Our Galaxy</i>” (Nobel Prize in Physics 2020) made by Prof. R. Genzel and A. Ghez is a confirmation of one of the most important predictions of WUM in 2013: “<i>Macroobjects of the World have cores made up of the discussed DM particles. Other particles, including DM and baryonic matter, form shells surrounding the cores</i>”. 展开更多
关键词 Hypersphere World-Universe Model Law of Conservation of Angular Momentum Dark Epoch Rotational Fission Luminous Epoch Dark Matter Particles Macroobject shell Model Dark Matter Core Medium of the World Dark Matter Fermi Bubbles Galactic Wind solar Wind Gamma-Ray Bursts Gravitational Bursts Intergalactic Plasma Cosmological Time solar Time Macroobjects supremacy of Matter Gravitomagnetic parameter Impedance Energy Density Gravitational parameter Hubble’s parameter Temperature of Microwave Background Radiation Inter-Connectivity of Primary Cosmological parameters Dark Matter Reactor
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PCB Base Log-periodic Antenna for Mobile Communications 被引量:3
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作者 B.A.M P.C.DHARMARATHNA H.D.T.S MADUSANKA M.A.A.KARUNARATHNA 《Instrumentation》 2021年第3期46-51,共6页
A log-periodic antenna can provide directivity and gain when operating in a wide band.The log-periodic antenna is used in many applications where wide bandwidth is required along with direct and medium gain.This resea... A log-periodic antenna can provide directivity and gain when operating in a wide band.The log-periodic antenna is used in many applications where wide bandwidth is required along with direct and medium gain.This research implements a sequential approach to the design and simulation of the performance of a printed log-periodic dipole antenna(LPDA)capable of operating in the 1800 MHz frequency range.The advantage of this antenna is the compactness and easy integration into planar circuits suitable for applications requiring wide bandwidth and high gain.The dimension of the designed antenna was originally calculated taking high frequency as 1885 MHz and low frequency as 1805 MHz,then modeled using HFSS-13 electromagnetic simulation to determine the effect of substrate dielectric properties on dipole width and length for element optimization.The design was verified by creating and measuring S11 and radiation diagrams.The designed antenna has a total gain of 7.9 dB and a wide bandwidth. 展开更多
关键词 Printed Log-periodic Dipole Antenna s parameters BANDWIDTH GAIN
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基于参数化设计方法的S弯扩压器性能分析 被引量:1
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作者 赵士洋 钟易成 《机械制造与自动化》 2010年第6期18-21,共4页
设计了一套S弯扩压器轮廓模型的参数化生成程序,利用这套程序生成了13个模型,并进行了性能分析,得出了分叉截面位置、S弯段轴向长度、最大圆截面半径、最大圆截面位置四组参数对扩压器性能的影响规律。通过分析可知在分叉截面位置离进... 设计了一套S弯扩压器轮廓模型的参数化生成程序,利用这套程序生成了13个模型,并进行了性能分析,得出了分叉截面位置、S弯段轴向长度、最大圆截面半径、最大圆截面位置四组参数对扩压器性能的影响规律。通过分析可知在分叉截面位置离进口近一点、S弯段轴向长度长一点、最大圆截面半径大一点、最大圆截面位置靠前一点的情况下,扩压器的性能较好。 展开更多
关键词 s弯扩压器 参数化方法 性能分析
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