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A modified multi-group model of angular and momentum distribution of cosmic ray muons for thickness measurement and material discrimination of slabs 被引量:5
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作者 Sa Xiao Wei-Bo He +2 位作者 Ming-Cong Lan Ying Chen Mao-Bing Shuai 《Nuclear Science and Techniques》 SCIE CAS CSCD 2018年第2期111-117,共7页
Muon tomography is a capable imaging technique to measure the geometry of high-Z objects. However,most existed algorithms used in muon tomography have obscured the effects of angular distribution and momentum spectra ... Muon tomography is a capable imaging technique to measure the geometry of high-Z objects. However,most existed algorithms used in muon tomography have obscured the effects of angular distribution and momentum spectra of cosmic ray muons and reduced the spatial resolution. We present a modified multi-group model that takes into account these effects and calibrates the model by the material of lead. Performance tests establish that the model is capable of measuring the thickness of a Pb slab and identifying the material of an unknown slab on a reasonable exposure timescale, in both cases of complete and incomplete angular data. Results show that the modified multi-group model is helpful for improvements in image resolution in real applications. 展开更多
关键词 MUON tomography MODIFIED MULTI-GROUP model ANGULAR distribution momentum spectra
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Wind Structure in an Intermediate Boundary Layer Model Based on Ekman Momentum Approximation
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作者 谈哲敏 王元 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2002年第2期266-278,共13页
A quasi three–dimensional, intermediate planetary boundary layer (PBL) model is developed by including inertial acceleration with the Ekman momentum approximation, but a nonlinear eddy viscosity based on Blackadar’s... A quasi three–dimensional, intermediate planetary boundary layer (PBL) model is developed by including inertial acceleration with the Ekman momentum approximation, but a nonlinear eddy viscosity based on Blackadar’s scheme was included to improve the theoretical model proposed by Tan and Wu (1993). The model could keep the same complexity as the classical Ekman model in numerical, but extends the conventional Ekman model to include the horizontal accelerated flow with the Ekman momentum approximation. A comparison between this modified Ekman model and other simplified accelerating PBL models is made. Results show that the Ekman model overestimates (underestimates) the wind speed and pumping velocity in the cyclonic (anticyclonic) shear flow due to the neglect of the acceleration flow, however, the semi–geostrophic Ekman model overestimates the acceleration effects resulting from the underestimating (overestimating) of the wind speed and pumping velocity in the cyclonic (anticyclonic) shear flow. The Ekman momentum approximation boundary layer model could be applied to the baroclinic atmosphere. The baroclinic Ekman momentum approximation boundary layer solution has both features of classical baroclinic Ekman layer and the Ekman momentum approximate boundary lager. 展开更多
关键词 Wind structure Ekman momentum approximation Boundary layer model
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Angular Momentum Dependent Exciton Model
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作者 Zhang, Jingshang Wen, Yuanqi 《Chinese journal of nuclear physics》 EI 1994年第2期153-159,共7页
To consider the angular momentum and parity conservation the angular mo-mentum (J) and parity (π) should be addressed in the master equation of the excitonmodel.Therefore the internal transition rates and the emissio... To consider the angular momentum and parity conservation the angular mo-mentum (J) and parity (π) should be addressed in the master equation of the excitonmodel.Therefore the internal transition rates and the emission rates must be Jπ depen-dent.The angular momentum factor of the internal transition rates is given and the an-gular momentum conservation effect is discussed. 展开更多
关键词 ANGULAR momentum PARITY CONSERVATION EXCITON model
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基于叶素动量理论的风机叶片动力学特性代理建模
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作者 徐小宇 陈遗志 +2 位作者 王伟 靳剑钊 张清弛 《电工电能新技术》 北大核心 2026年第3期20-29,共10页
功率预测是风电大规模安全可靠接入电力系统的关键技术,当前主要采用的纯数据驱动方法,存在可解释性不佳、偏差较大等不足。为了更有效地指导风力机组的功率预测,本文针对风电机组的核心部件叶片,提出一种风机叶片空气动力学特性的代理... 功率预测是风电大规模安全可靠接入电力系统的关键技术,当前主要采用的纯数据驱动方法,存在可解释性不佳、偏差较大等不足。为了更有效地指导风力机组的功率预测,本文针对风电机组的核心部件叶片,提出一种风机叶片空气动力学特性的代理建模方法。该方法基于叶素动量理论,将叶片分为若干叶素,在不同的风速和攻角的工况下,逐一对叶素进行湍流场分析,得到相应的升力和阻力等动力学特性,并采用克里金法构建出叶素的代理模型,进而通过沿叶片展向积分获得叶片整体的动力学特性代理模型。结合实际叶片,给出详细的代理模型构建和利用全流程。该方法具有物理模型与数据驱动融合的特性,可作为系统级快速分析模型,为风机设计和运行等场景下的机组级、风场级的功率预测提供支撑。 展开更多
关键词 风力涡轮机叶片 叶素动量理论 代理模型 空气动力学特性 风功率预测
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地质遗迹保护利用新模式新动能及支持政策研究——以江苏为典型案例
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作者 郭刚 孙欣欣 徐士银 《中国国土资源经济》 2026年第3期64-70,共7页
江苏省将地质遗迹保护与旅游、教育、文化、酒店、绿色等产业发展相结合,地质遗迹保护工作迸发出强劲动能,出现许多保护利用的新形式。文章收集利用以往遗迹调查的成果,结合实地补充调查与调研,梳理与总结江苏省地质遗迹保护利用的现状... 江苏省将地质遗迹保护与旅游、教育、文化、酒店、绿色等产业发展相结合,地质遗迹保护工作迸发出强劲动能,出现许多保护利用的新形式。文章收集利用以往遗迹调查的成果,结合实地补充调查与调研,梳理与总结江苏省地质遗迹保护利用的现状。按照遗迹保护与管理的形式,划分出六种主要模式,其中包括地质主题酒店与公园、地质文化村(镇)与特色田园乡村等新模式。依据模式各自的特点,从顶层设计和典型实例分析出发,讨论了未来地质遗迹保护利用的新趋势及对策。 展开更多
关键词 地质遗迹 保护与利用 新模式 新动能 政策研究 江苏省
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丽江机场地面大风时间变化特征及形成机制分析
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作者 赵元枫 肖天贵 +1 位作者 魏翔 时一文 《高原气象》 北大核心 2026年第1期217-232,共16页
随着我国航空运输业的快速发展,高原机场的特殊气象条件对飞行安全的影响日益凸显。其中,大风是影响飞行安全与效率的核心要素。利用2021-2023年丽江机场地面观测资料和ERA5再分析资料,对丽江机场地面大风时间变化特征及其形成机制进行... 随着我国航空运输业的快速发展,高原机场的特殊气象条件对飞行安全的影响日益凸显。其中,大风是影响飞行安全与效率的核心要素。利用2021-2023年丽江机场地面观测资料和ERA5再分析资料,对丽江机场地面大风时间变化特征及其形成机制进行分析。结果表明:(1)丽江机场地面大风主要发生在每年1-4月的干季,且集中在每日05:00-11:00(世界时,下同),其中07:00-09:00为大风高发时段,占大风事件总数的54%。(2)大风事件的发生通常伴随风向的显著转换,特别是在03:00前后,风向由偏北风迅速转为偏南风,风速在此后显著增加。地面大风过程中,尽管正侧风风速未达到限制飞机起降的标准,但部分极端大风事件中正侧风风速超过10 m·s^(-1),仍可能对飞行安全构成威胁。(3)物理量场和环流背景分析表明,午后热低压驱动地面变压风辐合,使得垂直方向对流活动增强破坏了低层大气的稳定层结,进而通过湍流混合作用诱发500 hPa西风急流动量下传形成地面大风。此外,寒潮爆发前北方冷涡对500 hPa西风气流的增速进一步增强了地面大风。通过分析极端地面大风个例的热力与动力驱动机制,构建地面大风概念模型,为进一步提高大风预警精度及飞行安全保障能力提供理论依据。(4)风切变特征表现出明显的时空规律:地面风增速阶段450~550 hPa风切变增强,550~650 hPa风切变减弱;地面风减速阶段450~550 hPa风切变减弱,550~650 hPa风切变增强。这一变化特征为风切变的预警提供了重要参考。 展开更多
关键词 丽江机场 地面大风 热低压 动量下传 概念模型
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高抗干扰性的无力传感器工业机器人外力估计方法
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作者 郭万金 利乾辉 +4 位作者 徐明坤 侯旭栋 刘孝恒 曹雏清 赵立军 《机械工程学报》 北大核心 2026年第3期366-383,共18页
为了解决工业机器人外力估计依赖于精确的动力学模型、抗干扰性差、精度低和可解释性不足的问题,提出了一种高抗干扰性的无力传感器工业机器人外力估计方法,实现了高抗干扰性机器人外力估计。首先,考虑关节摩擦力矩和外力影响建立了3T2... 为了解决工业机器人外力估计依赖于精确的动力学模型、抗干扰性差、精度低和可解释性不足的问题,提出了一种高抗干扰性的无力传感器工业机器人外力估计方法,实现了高抗干扰性机器人外力估计。首先,考虑关节摩擦力矩和外力影响建立了3T2R构型五自由度工业机器人动力学模型,并引入Stribeck摩擦-速度模型描述摩擦力矩的非线性特征;其次,利用自适应率增益参数优化的自适应超螺旋滑模广义动量观测器估计机器人关节外力矩,以提高关节外力矩的估计精度,降低对精确动力学模型的依赖,增强关节外力矩估计方法的可解释性;再次,利用雅可比矩阵建立机器人关节外力矩与机器人外力的映射关系,实现机器人外力估计;将所提方法与自适应超螺旋滑模、超螺旋滑模和一阶广义动量观测器方法进行对比实验分析,以关节1为例,所提方法与真实关节外力矩的平均绝对误差减小了12.9%、39.9%和57.9%,并利用所建立映射关系获得机器人外力估计,所提方法具有更高的估计精度,验证了所提方法的有效性;最后,施加同一随机扰动后将所提方法与一阶广义动量观测器方法进行对比,所提方法与真实关节外力矩均方根误差增大了1.5%,而一阶广义动量观测器方法增大了43.3%,验证了所提方法具有更强的抗扰性。 展开更多
关键词 工业机器人 外力估计 摩擦力矩模型 广义动量观测器 超螺旋滑模
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Dynamic Modeling and Motion Simulation for A Winged Hybrid-Driven Underwater Glider 被引量:34
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作者 王树新 孙秀军 +2 位作者 王延辉 武建国 王晓鸣 《China Ocean Engineering》 SCIE EI 2011年第1期97-112,共16页
PETREL, a winged hybrid-driven underwater glider is a novel and practical marine survey platform which combines the features of legacy underwater glider and conventional AUV (autonomous underwater vehicle). It can b... PETREL, a winged hybrid-driven underwater glider is a novel and practical marine survey platform which combines the features of legacy underwater glider and conventional AUV (autonomous underwater vehicle). It can be treated as a multi-rigid-body system with a floating base and a particular hydrodynamic profile. In this paper, theorems on linear and angular momentum are used to establish the dynamic equations of motion of each rigid body and the effect of translational and rotational motion of internal masses on the attitude control are taken into consideration. In addition, due to the unique external shape with fixed wings and deflectable rudders and the dual-drive operation in thrust and glide modes, the approaches of building dynamic model of conventional AUV and hydrodynamic model of submarine are introduced, and the tailored dynamic equations of the hybrid glider are formulated. Moreover, the behaviors of motion in glide and thrust operation are analyzed based on the simulation and the feasibility of the dynamic model is validated by data from lake field trials. 展开更多
关键词 hybrid-driven underwater glider autonomous underwater vehicle dynamic modeling momentum theorem
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Double Multiple Streamtube Model and Numerical Analysis of Vertical Axis Wind Turbine 被引量:2
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作者 Habtamu Beri Yingxue Yao 《Energy and Power Engineering》 2011年第3期262-270,共9页
The present paper contributes to the modeling of unsteady flow analysis of vertical axis wind turbine (VAWT). Double multiple streamtube (DSMT) model was applied for the performance prediction of straight bladed fixed... The present paper contributes to the modeling of unsteady flow analysis of vertical axis wind turbine (VAWT). Double multiple streamtube (DSMT) model was applied for the performance prediction of straight bladed fixed pitch VAWT using NACA0018 airfoil at low wind speed. A moving mesh technique was used to investigate two-dimensional unsteady flow around the same VAWT model with NACA0018 airfoil modified to be flexible at 150 from the main blade axis of the turbine at the trailing edge located about 70 % of the blade chord length using fluent solving Reynolds average Navier-strokes equation. The results obtained from DMST model and the simulation results were then compared. The result shows that the CFD simulation with airfoil modified has shown better performance at low tip speed ratios for the modeled turbine. 展开更多
关键词 Wind TURBINE ACTUATOR DISK momentum model STREAM Tube VAWT CFD
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Coupling model for waves propagating over a porous seabed 被引量:1
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作者 C.C.Liao Z.Lin +1 位作者 Y.Guo D.-S.Jeng 《Theoretical & Applied Mechanics Letters》 CAS CSCD 2015年第2期85-88,共4页
The wave-seabed interaction issue is of great importance for the design of foundation around marine infrastructures. Most previous investigations for such a problem have been limited to uncoupled or one- way coupled m... The wave-seabed interaction issue is of great importance for the design of foundation around marine infrastructures. Most previous investigations for such a problem have been limited to uncoupled or one- way coupled methods connecting two separated wave and seabed sub models with the continuity of pressures at the seabed surface. In this study, a strongly coupled model was proposed to realize both wave and seabed processes in a same program and to calculate the wave fields and seabed response simultaneously. The information between wave fields and seabed fields were strongly shared and thus results in a more profound investigation of the mechanism of the wave-seabed interaction. In this letter, the wave and seabed models were validated with previous experimental tests. Then, a set of application of present model were discussed in prediction of the wave-induced seabed response. Numerical results show the wave-induced liquefaction area of coupled model is smaller than that of uncoupled model. 展开更多
关键词 Coupled model momentum source Internal wave-maker Seabed response Pore pressure Liquefaction
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基于约束跟随理论的动量轮倒立摆控制研究
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作者 管震涛 刘康 +2 位作者 张远辉 卜洋 付铎 《现代电子技术》 北大核心 2026年第1期108-116,共9页
在处理欠驱动系统的控制问题时,传统控制方法常常面临跟踪精度低、能效差和控制律复杂等挑战。针对动量轮倒立摆这一典型的欠驱动非线性系统,文中提出一种新颖的基于约束跟随理论的控制策略。与传统方法相比,该策略无需线性化处理,能够... 在处理欠驱动系统的控制问题时,传统控制方法常常面临跟踪精度低、能效差和控制律复杂等挑战。针对动量轮倒立摆这一典型的欠驱动非线性系统,文中提出一种新颖的基于约束跟随理论的控制策略。与传统方法相比,该策略无需线性化处理,能够充分利用系统的非线性特性,从而提升控制性能。首先建立了动量轮倒立摆的机械结构模型,并基于拉格朗日方程构建其动力学模型。通过将倒立摆的期望平衡角度设定为伺服约束,基于约束跟随理论推导出满足约束的力矩解析表达式,避免引入拉格朗日乘子等辅助变量。在Matlab/Simulink/Simscape环境中进行的仿真实验验证,以及基于ESP32控制核心的实验平台搭建,均证实了所提控制方法的有效性和优越性。与传统的线性二次调节器(LQR)控制方法相比,所提方法在控制效果上表现出显著优势。 展开更多
关键词 动量轮倒立摆 欠驱动系统 非线性系统 拉格朗日方程 动力学模型 约束跟随
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RELAXATION TIME LIMITS PROBLEM FOR HYDRODYNAMIC MODELS IN SEMICONDUCTOR SCIENCE 被引量:3
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作者 黎勇 《Acta Mathematica Scientia》 SCIE CSCD 2007年第2期437-448,共12页
In this article, two relaxation time limits, namely, the momentum relaxation time limit and the energy relaxation time limit are considered. By the compactness argument, it is obtained that the smooth solutions of the... In this article, two relaxation time limits, namely, the momentum relaxation time limit and the energy relaxation time limit are considered. By the compactness argument, it is obtained that the smooth solutions of the multidimensional nonisentropic Euler-Poisson problem converge to the solutions of an energy transport model or a drift diffusion model, respectively, with respect to different time scales. 展开更多
关键词 Hydrodynamic models nonisentropic Euler-Poisson momentum relaxation time limit energy relaxation time limit
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Theoretical Model Calculation for d+~8Li Reaction
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作者 HAN Yin-Lu GUO Hai-Rui ZHANG Yue ZHANG Jing-Shang 《Communications in Theoretical Physics》 SCIE CAS CSCD 2008年第8期463-467,共5页
Based on the theoretical models for light nuclei, the calculations of reaction cross sections and the angular distributions for d +^8Li reaction are performed. Since all of the particle emissions are from the compoun... Based on the theoretical models for light nuclei, the calculations of reaction cross sections and the angular distributions for d +^8Li reaction are performed. Since all of the particle emissions are from the compound nucleus to the discrete levels, the angular momentum coupling effect in pre-equilibrium mechanism is taken into account. The three- body break-up process and the recoil effect are involved. The theoretical calculated results are compared to existing experimental data. 展开更多
关键词 deuteron-induced reaction cross sections light nuclei of the 1p shell angular momentum andparity dependence exciton model improved Iwamoto-Harada model
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Transverse momentum and transverse mass distributions of charged hadrons produced in Au-Au collisions at high energies
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作者 刘福虎 《Chinese Physics B》 SCIE EI CAS CSCD 2008年第7期2458-2465,共8页
The transverse momentum distribution and the transverse mass distribution of charged hadrons produced in nucleus nucleus collisions at high energies are described by using a two-cylinder model. The results calculated ... The transverse momentum distribution and the transverse mass distribution of charged hadrons produced in nucleus nucleus collisions at high energies are described by using a two-cylinder model. The results calculated by the model are compared and found to be in agreement with the experimental data of the STAR and E895 Collaborations, measured in A^Au collisions at the relativistic heavy ion collider (RHIC) and alternating-gradient synchrotron (AGS) energies, respectively. In the energy range concerned, the excitation degree of emission source close to the central axis of cylinders increases obviously with the collision centrality and incident energy increasing, but it does not show any obvious change with the increase of the (pseudo)rapidity in central collisions. The excitation degree of emission source close to the side-surface of cylinders does not show any obvious change with the collision centrality, the (pseudo)rapidity, and the incident energy increasing. 展开更多
关键词 transverse momentum two-cylinder model nucleus-nucleus collisions
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Study on Stack Effect of Stairwell by Numerical Model of Leakage Flow through Gap of Door
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作者 Jung-Yup Kim Ji-Seok Kim 《Open Journal of Fluid Dynamics》 2013年第4期241-247,共7页
Since stack effect that occurs in high-rise buildings has an effect on the indoor environment of the buildings, energy loss and smoke control in case of a fire, there is a need to conduct research on this. For an anal... Since stack effect that occurs in high-rise buildings has an effect on the indoor environment of the buildings, energy loss and smoke control in case of a fire, there is a need to conduct research on this. For an analysis of the stack effect, analysis methods on the leakage flow through gap of interior door shall be formulated. Until now, studies related to the gap leakage flow in buildings have mainly analyzed flow field and pressure in the buildings one-dimensionally using pressure difference-leakage flowrate relations of Orifice Equation and a network numerical analysis algorithm that as- sumes each compartment in the buildings as a single point. In this study, the Momentum Loss Model which enables pressure drop to be proportional to the flow velocity through the gap of door in computational domain of 3-dimensional numerical analysis was proposed to reflect the gap flow phenomenon effectively in 3-dimensional numerical analysis. Using the proposed model, 3-dimensional numerical analysis of the stack effect on the stairs in buildings was performed, and the effects of separation door and lobby between stair and accommodation on the stack effect were investigated. 展开更多
关键词 STACK Effect LEAKAGE Flow GAP of DOOR momentum Loss model Separation DOOR NUMERICAL Analysis
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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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The Investigation of Atmospheric Angular Momentum as a Contributor to Polar Wobble and Length of Day Change with AMIP II GCM Data 被引量:1
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作者 钟敏 闫昊明 朱耀仲 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2002年第2期287-296,共10页
The atmospheric angular momentum (AAM) functions in terms of contribution to polar wobble and length of day change, are calculated from the output data of GSM9603 global circulation model (GCM) of Japan Meteorological... The atmospheric angular momentum (AAM) functions in terms of contribution to polar wobble and length of day change, are calculated from the output data of GSM9603 global circulation model (GCM) of Japan Meteorological Agency (JMA), from the reanalysis data of the National Centers for the Environmental Prediction (NCEP)/National Center for Atmospheric Research (NCAR), and from the operational objective analysis data of JMA, respectively. The comparison shows that during the period from 1985 to 1995, the values of the pressure terms in the equatorial components of AAM functions calculated from three data sets agree with each other better along 90°E longitude than along Greenwich meridian direction. The axial component of relative AAM function estimated from GSM 9603 agrees well with those from the other two data sets in terms of seasonal variations with the moderate amplitudes, but not so well with the composite axial component of relative AAM functions estimated from 23 GCM models anticipating in the first phase of AMIP. In addition, its interannual variation from 1979 to 1996 shows the main characteristics of ENSO evolution, just as does the axial component of relative AAM function estimated from NCEP reanalysis data except for the period of anomalous ENSO from 1991 to 1993. 展开更多
关键词 Atmospheric model Inter–comparison Project (AMIP) Atmospheric Angular momentum (AAM) Earth rotation
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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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基于改进BP神经网络的钢筋混凝土桥墩等效塑性铰长度预测模型研究
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作者 孙治国 刘云华 +2 位作者 刘瑜丽 张春辉 Uzdin A M 《防灾科技学院学报》 2025年第4期72-81,共10页
为提高钢筋混凝土桥墩等效塑性铰长度的预测精度,收集整理了133组钢筋混凝土桥墩抗震试验数据,构建了包含桥墩高度、截面尺寸、混凝土抗压强度、纵筋直径、纵筋屈服强度、纵筋配筋率、箍筋屈服强度、体积配箍率和轴压比等10个影响因素... 为提高钢筋混凝土桥墩等效塑性铰长度的预测精度,收集整理了133组钢筋混凝土桥墩抗震试验数据,构建了包含桥墩高度、截面尺寸、混凝土抗压强度、纵筋直径、纵筋屈服强度、纵筋配筋率、箍筋屈服强度、体积配箍率和轴压比等10个影响因素的数据集。在传统BP神经网络基础上,引入动量算法与RMSprop自适应学习率算法,建立了改进的BP神经网络预测模型,用以预测钢筋混凝土墩柱的等效塑性铰长度。为验证模型预测精度与样本量合理性,开展5次随机划分实验,结果显示各性能指标变异系数均小于15%, 133组样本量足以支撑稳定预测。将改进的BP神经网络预测模型与传统BP神经网络、动量BP神经网络及6种经验公式模型进行了对比分析,结果表明:改进BP神经网络模型在预测精度与稳定性方面均显著优于其他模型,能够更为准确地预测钢筋混凝土桥墩等效塑性铰长度。 展开更多
关键词 桥梁抗震 等效塑性铰长度 BP模型预测 动量 RMSprop算法
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JWST Discoveries—Confirmation of World-Universe Model Predictions
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作者 Vladimir S. Netchitailo 《Journal of High Energy Physics, Gravitation and Cosmology》 CAS 2022年第4期1134-1154,共21页
In 1937, P. Dirac proposed the Large Number Hypothesis and Hypothesis of Variable Gravitational Constant [1], and later added notion of Continuous Creation of Matter in the World [2]. Developed Hypersphere World-Unive... In 1937, P. Dirac proposed the Large Number Hypothesis and Hypothesis of Variable Gravitational Constant [1], and later added notion of Continuous Creation of Matter in the World [2]. Developed Hypersphere World-Universe Model (WUM) follows these ideas, albeit introducing different mechanism of Matter creation. Most direct observational evidence of validity of WUM are: 1) Microwave Background Radiation and Intergalactic Plasma speak in favor of existence of Medium;2) Laniakea Supercluster with binding mass ~10<sup>17</sup>M<sub>&odot;</sub> is home to Milky Way (MW) galaxy and ~10<sup>5</sup> other nearby galaxies, which did not start their movement from Initial Singularity (see Figure 1);3) MW is gravitationally bounded with Virgo Supercluster (VSC) and has Orbital Angular Momentum calculated based on distance of 65 Mly from VSC and orbital speed of ~400 km·s<sup>-1</sup>, which far exceeds rotational angular momentum of MW;4) Mass-to-light ratio of VSC is ~300 times larger than that of Solar ratio. Similar ratios are obtained for other superclusters (see Figure 2). These ratios are main arguments in favor of the presence of tremendous amounts of Dark Matter (DM) in the World. JWST discoveries confirm the most important predictions of WUM in 2018: 1) Absolute Age of World is 14.22 Gyr;2) Dark Epoch (spanning for Laniakea Supercluster (LSC) from the Beginning of World for 0.45 Gyr) when only DM Macroobjects (MOs) form and evolve;3) Luminous Epoch (ever since, 13.77 Gyr for LSC) when Luminous MOs (superclusters, galaxies, extrasolar systems, etc.) emerge;4) Transition from Dark Epoch to Luminous Epoch is due to Explosive Rotational Fission of Overspinning (surface speed at equator exceeding escape velocity) DM Supercluster’s Cores and self-annihilation of DM Particles (DMPs);5) MOs of World form from top (Superclusters) down to Galaxies and Extrasolar systems in parallel around different Cores made up of different DMPs;6) 3D Finite Boundless World presents a Patchwork Quilt of different Luminous Superclusters, which emerged in different places of World at different Cosmological times. 展开更多
关键词 James Webb Space Telescope World-Universe model Medium Angular momentum Dark Matter Dark Epoch Luminous Epoch Rotational Fission Patchwork Quilt Early-Galaxies Inter-Connectivity of Primary Cosmological Parameters
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