期刊文献+
共找到377篇文章
< 1 2 19 >
每页显示 20 50 100
Ab initio calculation of accurate dissociation energy, potential energy curve and dipole moment function for the A^1∑+ state ^7LiH molecule 被引量:1
1
作者 施德恒 刘玉芳 +2 位作者 孙金锋 杨向东 朱遵略 《Chinese Physics B》 SCIE EI CAS CSCD 2006年第5期1015-1021,共7页
The reasonable dissociation limit of the A^1∑+ state ^7LiH molecule is obtained. The accurate dissociation energy and the equilibrium geometry of this state are calculated using a symmetry-adapted-cluster configurat... The reasonable dissociation limit of the A^1∑+ state ^7LiH molecule is obtained. The accurate dissociation energy and the equilibrium geometry of this state are calculated using a symmetry-adapted-cluster configuration-interaction method in complete active space for the first time, The whole potential energy curve and the dipole moment function for the A^1∑+ state are calculated over a wide internuclear separation range from about 0.1 to 1.4 nm. The calculated equilibrium geometry and dissociation energy of this potential energy curve are of Re=0.2487 nm and De=1.064eV, respectively. The unusual negative values of the anharmonicity constant and the vibration-rotational coupling constant are of ωeXe=-4.7158cm^-1 and αe=0.08649cm^-1, respectively. The vertical excitation energy from the ground to the A^1∑+ state is calculated and the value is of 3.613eV at 0.15875nm (the equilibrium position of the ground state). The highly anomalous shape of this potential energy curve, which is exceptionally flat over a wide radial range around the equilibrium position, is discussed in detail. The harmonic frequency value of 502.47cm^-1 about this state is approximately estimated. Careful comparison of the theoretical determinations with those obtained by previous theories about the A^1∑+ state dissociation energy clearly shows that the present calculations are much closer to the experiments than previous theories, thus represents an improvement. 展开更多
关键词 ab initio calculation dissociation energy dipole moment potential energy curve
下载PDF
Estimating probability curves of rock variables using orthogonal polynomials and sample moments 被引量:3
2
作者 邓建 边利 《Journal of Central South University of Technology》 2005年第3期349-353,共5页
A new algorithm using orthogonal polynomials and sample moments was presented for estimating probability curves directly from experimental or field data of rock variables. The moments estimated directly from a sample ... A new algorithm using orthogonal polynomials and sample moments was presented for estimating probability curves directly from experimental or field data of rock variables. The moments estimated directly from a sample of observed values of a random variable could be conventional moments (moments about the origin or central moments) and probability-weighted moments (PWMs). Probability curves derived from orthogonal polynomials and conventional moments are probability density functions (PDF), and probability curves derived from orthogonal polynomials and PWMs are inverse cumulative density functions (CDF) of random variables. The proposed approach is verified by two most commonly-used theoretical standard distributions: normal and exponential distribution. Examples from observed data of uniaxial compressive strength of a rock and concrete strength data are presented for illustrative purposes. The results show that probability curves of rock variable can be accurately derived from orthogonal polynomials and sample moments. Orthogonal polynomials and PWMs enable more secure inferences to be made from relatively small samples about an underlying probability curve. 展开更多
关键词 岩石变数 概率曲线 正交多项式 重力矩
下载PDF
Potential energy curves, transition dipole moments, and radiative lifetimes of KBe molecule
3
作者 万明杰 金成国 +2 位作者 虞游 黄多辉 邵菊香 《Chinese Physics B》 SCIE EI CAS CSCD 2017年第3期291-296,共6页
An ab initio calculations on the ground and low-lying excited statesX2∑+,2^2∑+,3^2∑+,1^4∏,2^4∏,1^4∑+,2^4∑+,and 3^4∑+of KBe molecule have been performed using multireference configuration interaction (M... An ab initio calculations on the ground and low-lying excited statesX2∑+,2^2∑+,3^2∑+,1^4∏,2^4∏,1^4∑+,2^4∑+,and 3^4∑+of KBe molecule have been performed using multireference configuration interaction (MRCI) plus Davidsoncorrections (MRCI+Q) approach with all electron basis set aug-cc-pCV5Z-DK for Be and def2-AQZVPP-JKFI for K.3^2∑+,1^4∏,2^4∏,1^4∑+,2^4∑+and3^4∑+states are investigated for the first time. Inner shell electron correlations are computed on the potential energy curves (PECs) calculations. The spectroscopic and molecular parameters are also predicted. In addition, The transition properties including transition dipole moment, Franck-Condon factors qv′v″, Einstein coefficients Av′v″, and the radiative lifetimesτ′for the2^2∑+-X2∑+,3^2∑+-X2∑+,and 2^4∏-1^4∏ transitions are predictedat the same time. 展开更多
关键词 potential energy curves transition dipole moment Franck-Condon factors Einstein coefficients
下载PDF
Diverse features of magnetization curves of uniaxial crystals:A simulation study
4
作者 Hala A.Sobh Samy H.Aly 《Chinese Physics B》 SCIE EI CAS CSCD 2017年第1期454-465,共12页
We present a simulation of the magnetization curves, energy, probability, and torque landscapes of uniaxial systems with up to five anisotropy constants. The total energy used in the simulation is the sum of the aniso... We present a simulation of the magnetization curves, energy, probability, and torque landscapes of uniaxial systems with up to five anisotropy constants. The total energy used in the simulation is the sum of the anisotropy and Zeeman energies. The exchange interaction is not considered in the present work in which we treat single-domain-particle systems within a classical mechanics-based model. Diverse features of the calculated magnetization curves are highlighted for the studied systems. These diverse features are strongly dependent on the sign and magnitude of the simulation parameters.The model is versatile enough to handle both hypothetical and real material systems, e.g. HoFe(11)Ti and Y2Co(17). 展开更多
关键词 magnetization curve saturation moments magnetic anisotropy ferromagnetic metals and alloys
下载PDF
DIRECTIVITY OPTIMIZATION OF CURVED SURFACE DIPOLE ANTENNAS
5
作者 王均宏 任朗 《Journal of Electronics(China)》 1994年第4期322-331,共10页
Based on the calculation of the characteristic parameters by moment method, the curved surface dipoles are optimized by an optimization method, the maximum directivities of some V-curved and Gauss-curved surface dipol... Based on the calculation of the characteristic parameters by moment method, the curved surface dipoles are optimized by an optimization method, the maximum directivities of some V-curved and Gauss-curved surface dipoles are given. 展开更多
关键词 ANTENNAS curved SURFACE DIPOLES DIRECTIVITY OPTIMIZATION moment method
下载PDF
基于代理模型的输电塔半刚性节点弯矩-转角曲线预测方法
6
作者 刘泉 李正良 +1 位作者 彭思思 王涛 《重庆大学学报》 CAS CSCD 北大核心 2024年第4期86-93,共8页
为了准确、高效地评估输电塔半刚性节点的力学特性,提出了一种基于代理模型的输电塔半刚性节点弯矩-转角曲线预测方法,通过引入代理模型方法近似半刚性节点几何尺寸与极限抗弯承载力、初始转动刚度之间的函数关系,建立具有较高精度的预... 为了准确、高效地评估输电塔半刚性节点的力学特性,提出了一种基于代理模型的输电塔半刚性节点弯矩-转角曲线预测方法,通过引入代理模型方法近似半刚性节点几何尺寸与极限抗弯承载力、初始转动刚度之间的函数关系,建立具有较高精度的预测模型,进而结合Kish-Chen幂函数模型拟合输电塔半刚性节点的弯矩-转角曲线。结果表明,提出的基于代理模型的输电塔半刚性节点弯矩-转角曲线预测方法能减少实验和数值模拟的成本,较好地模拟输电塔半刚性节点实际受力-变形情况,为输电塔半刚性节点的工程设计和理论研究提供了参考。 展开更多
关键词 代理模型 输电塔 半刚性节点 弯矩-转角曲线
下载PDF
钢结构半刚性连接节点研究现状
7
作者 佟林泽 董锦坤 《辽宁工业大学学报(自然科学版)》 2024年第1期38-43,共6页
半刚性连接具刚度、延性和载荷能力,抗震性能优越,施工难度低,是实用且经济的连接方式。但半刚性连接受力复杂,力学特性分析难度大,且国内规范中缺乏针对性的分类标准和设计方法。综合国内外文献规范,简述了梁柱节点的分类及特点,详细... 半刚性连接具刚度、延性和载荷能力,抗震性能优越,施工难度低,是实用且经济的连接方式。但半刚性连接受力复杂,力学特性分析难度大,且国内规范中缺乏针对性的分类标准和设计方法。综合国内外文献规范,简述了梁柱节点的分类及特点,详细介绍了钢结构半刚性节点连接类型、研究方法和研究成果,通过分析当前研究进展,指出未来所需研究的问题与方向,为钢结构半刚性节点研究、设计与实际运用提供思路与参考。 展开更多
关键词 钢结构 半刚性连接 梁柱节点 弯矩-转角曲线
下载PDF
SnS分子低激发态光谱性质理论研究
8
作者 张续文 闫爽 +2 位作者 吕浩男 张存华 李瑞 《高师理科学刊》 2024年第3期63-70,共8页
应用多参考组态相互作用(MRCI)方法计算了硫化锡(SnS)分子的第一解离极限对应的18个Λ-S态.计算时,Sn原子采用了包含ECP28MDF赝势的aug-cc-pwCVQWZ-PP基组,S原子采用aug-cc-pwCVQZ基组.根据计算得到的单点势能绘制了Sn S分子的势能曲线(... 应用多参考组态相互作用(MRCI)方法计算了硫化锡(SnS)分子的第一解离极限对应的18个Λ-S态.计算时,Sn原子采用了包含ECP28MDF赝势的aug-cc-pwCVQWZ-PP基组,S原子采用aug-cc-pwCVQZ基组.根据计算得到的单点势能绘制了Sn S分子的势能曲线(PECs).基于PECs,应用数值方法求解薛定谔方程,得到了束缚态的光谱常数,理论计算的结果与已有的实验结果吻合较好.计算了18个Λ-S态的永久偶极矩(PDMs),并讨论了其变化规律.此外,还计算了1^(3)Π,1^(1)Σ^(-),1^(1)Δ,1^(3)Σ^(-),1^(3)Δ,1^(3)Σ^(+)态的耦合矩阵元,通过分析耦合矩阵元阐明了电子态之间的相互作用.最后,分析了2^(1)Σ^(+)-X^(1)Σ^(+),1^(1)Π-X^(1)Σ^(+),1^(1)Π-1^(1)Δ,1^(1)Π-1^(1)Σ^(-)态的跃迁性质,包括跃迁偶极矩(TDMs),Franck-Condon因子(FCFs)和自发辐射寿命. 展开更多
关键词 SNS 势能曲线 光谱常数 跃迁偶极矩
下载PDF
基于参数化运动方程的电缆卷筒运动特性分析
9
作者 王凯 高广恒 《港口装卸》 2024年第1期21-24,45,共5页
在分析电缆卷筒设计基础上,建立一种电缆卷筒收缆过程参数化模型方程,并对计算结果进行图形化处理;在分别对恒张力约束条件下和恒力矩约束条件下的卷筒收缆工况进行分析基础上,获得不同工况下的力学特性曲线,提出一种变频式、力矩式和... 在分析电缆卷筒设计基础上,建立一种电缆卷筒收缆过程参数化模型方程,并对计算结果进行图形化处理;在分别对恒张力约束条件下和恒力矩约束条件下的卷筒收缆工况进行分析基础上,获得不同工况下的力学特性曲线,提出一种变频式、力矩式和磁滞式电缆卷筒的选型设计方法。该方法效率高,适应性好,对电缆卷筒的设计选型具有指导意义。 展开更多
关键词 电缆卷筒 参数化模型方程 恒张力约束 恒力矩约束 特性曲线
下载PDF
Frequency Time Analysis (FTAN) and Moment Tensor Inversion Solutions from Short Period Surface Waves in Cameroon (Central Africa) 被引量:2
10
作者 Eric N. Ndikum Charles T. Tabod Alain-Pierre K. Tokam 《Open Journal of Geology》 2014年第2期33-43,共11页
Short period surface waves generated by a local earthquake recorded by broadband seismometers at distances of about 186 to 778 km from the earthquake’s epicenter located in Cameroon (Central Africa) were processed fo... Short period surface waves generated by a local earthquake recorded by broadband seismometers at distances of about 186 to 778 km from the earthquake’s epicenter located in Cameroon (Central Africa) were processed for group velocity maps and dispersion waveforms using the frequency time analysis (FTAN) method. The resulting group velocity fundamental modes of the extracted Rayleigh and Love waves were used for a joint amplitude spectral and P polarity inversion using moment tensor inversion. The corresponding group velocity dispersion curves, the residual as a function of depth, the amplitude spectra and the moment tensor solutions of the regions from the epicenter to the different stations up to a depth of about 10 km were obtained. 展开更多
关键词 FREQUENCY TIME ANALYSIS (FTAN) Surface Waves Group Velocity Dispersion curveS moment TENSOR Inversion
下载PDF
Electronic Structure with Rovibrationl and Dipole Moment Study of the NiO Molecule
11
作者 Khalil Badreddine Nayla El-Kork Mahmoud Korek 《Journal of Modern Physics》 2012年第8期839-849,共11页
The potential energy curves have been investigated for the 40 lowest electronic states in the 2s+1Λ(±)representation below 25000 cm-1 of the molecule NiO via CASSCF, MRCI (single and double excitation with David... The potential energy curves have been investigated for the 40 lowest electronic states in the 2s+1Λ(±)representation below 25000 cm-1 of the molecule NiO via CASSCF, MRCI (single and double excitation with Davidson correction) and CASPT2 methods. The harmonic frequency ωe , the internuclear distance re, the rotational constant Be, the electronic energy with respect to the ground state Te, and the permanent dipole moment μ have been calculated. By using the canonical functions approach, the eigenvalues Ev, the rotational constant Bv and the abscissas of the turning points rmin and rmax have been calculated for the considered electronic states up to the vibration level v = 12. Eleven electronic states have been studied theoretically here for the first time. The comparison of these values to the theoretical and experimental results available in literature shows a very good agreement. 展开更多
关键词 ab INITIO CALCULATION NIO MOLECULE Potential Energy curves Spectroscopic CONSTANTS DIPOLE moment Rovibrational CALCULATION
下载PDF
Theoretical Study with Rovibrational and Dipole Moment Calculation of the SiO Molecule
12
作者 Khalil Badreddine Nayla El-Kork Mahmoud Korek 《Journal of Modern Physics》 2013年第1期82-93,共12页
Via CASSCF/MRCI and RSPT2 calculations (single and double excitation with Davidson correction) the potential en- ergy curves of 20 electronic states in the representation 2S+1Λ(±)of the molecule SiO have been ca... Via CASSCF/MRCI and RSPT2 calculations (single and double excitation with Davidson correction) the potential en- ergy curves of 20 electronic states in the representation 2S+1Λ(±)of the molecule SiO have been calculated. By fitting these potential energy curves to a polynomial around the equilibrium internuclear distance re, the harmonic frequency ωe, the rotational constant Be, and the electronic energy with respect to the ground state Te have been calculated. For the considered electronic states the permanent dipole moment μ have been plotted versus the internuclear distance r. Based on the canonical functions approach, the eigenvalues Ev, the rotational constant Bv and the abscissas of the turning points rmin and rmax have been calculated. The comparison of these values to the experimental and theoretical results available in the literature is presented. In the present work 8 higher electronic states have been studied theoretically for the first time. 展开更多
关键词 Ab INITIO CALCULATION SIO MOLECULE Potential Energy curves Spectroscopic CONSTANTS DIPOLE moment Rovibrational CALCULATION
下载PDF
外伸端板半刚性钢结构连接节点的弯矩-转角智能模型研究 被引量:2
13
作者 刘坚 肖海鹏 +9 位作者 刘长江 张专涛 王飞程 马宏伟 戚玉亮 招渝 彭林苗 任达 陈原 童华炜 《建筑钢结构进展》 CSCD 北大核心 2023年第6期43-50,共8页
为了寻找一种耗费人力更少、预测效果更好的外伸端板半刚性钢结构连接节点的弯矩-转角(M-θr)关系模型,提出将智能模型引入对该种半刚性连接节点M-θr曲线的预测。首先对现有钢结构梁柱半刚性连接节点M-θr关系经典模型进行了评述,采用... 为了寻找一种耗费人力更少、预测效果更好的外伸端板半刚性钢结构连接节点的弯矩-转角(M-θr)关系模型,提出将智能模型引入对该种半刚性连接节点M-θr曲线的预测。首先对现有钢结构梁柱半刚性连接节点M-θr关系经典模型进行了评述,采用其中的幂函数模型对一组试验做了计算并与试验结果进行对比;然后用非线性有限元法对外伸端板半刚性钢结构连接节点进行了计算,并把分析所得M-θr曲线与试验曲线做了比较分析;基于大量试验数据,研究确定了对该种半刚性连接节点M-θr性能影响较大的11个主要参数,并用MATLAB数值计算软件建立了智能模型,对外伸端板半刚性钢结构连接节点的M-θr关系进行了预测,将预测结果与试验值对比。最后发现智能模型不论是定性的曲线变化趋势、还是定量的数值大小,都优于现有幂函数模型和非线性有限元分析,具有更好的可靠性、实用性。所得结论,可为该类半刚性钢结构连接节点M-θr关系研究提供新的思路。 展开更多
关键词 智能模型 弯矩-转角曲线 半刚性节点 幂函数模型 非线性有限元分析
下载PDF
超冷(36D_(5/2)+6S_(1/2))里德伯分子的制备及其电偶极矩的测量 被引量:1
14
作者 焦月春 白景旭 +2 位作者 宋蓉 韩小萱 赵建明 《物理学报》 SCIE EI CAS CSCD 北大核心 2023年第3期62-68,共7页
里德伯-基态分子由一个里德伯原子和一个基态原子组成,束缚机制是里德伯电子与基态原子的低能电子散射相互作用.理论上,通过低能电子散射Fermi赝势模型,数值计算了铯(36D_(5/2)+6S_(1/2))里德伯-基态分子的绝热势能曲线,提取了里德伯分... 里德伯-基态分子由一个里德伯原子和一个基态原子组成,束缚机制是里德伯电子与基态原子的低能电子散射相互作用.理论上,通过低能电子散射Fermi赝势模型,数值计算了铯(36D_(5/2)+6S_(1/2))里德伯-基态分子的绝热势能曲线,提取了里德伯分子的束缚能和平衡核间距等光谱参数.实验上,利用双光子光缔合技术成功制备了散射三重态(^(T)∑,Triplet)和散射单重态-三重态混合(^(S,T)∑,Mixed)形成的里德伯-基态分子,获得了里德伯分子的光缔合光谱,测量的势阱深度与理论计算结果相吻合.另外,以散射三重态为例,分析了里德伯分子的光缔合光谱在外加电场中的展宽现象,获得其平均永久电偶极矩|d|为(12.10±1.65)Debye((4.76±0.65)ea_(0)),与理论计算结果保持一致.该研究为实验上制备D态里德伯-基态分子提供了可行的实验方案,对理解里德伯分子的光谱特性具有重要意义. 展开更多
关键词 超冷里德伯-基态分子 光缔合光谱 绝热势能曲线 电偶极矩
下载PDF
Centrifuge tests for seismic response of single pile foundation supported wind turbines in sand influenced by earthquake history 被引量:2
15
作者 Wang Yubing Zhang Zhongchang +1 位作者 Wu Xiaofeng Zhu Bin 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2023年第3期623-636,共14页
This paper reports on two sets of centrifuge model tests of wind turbines in dry sand and saturated sand subjected to earthquake sequences.The wind turbine system is composed of a single pile foundation and a wind tur... This paper reports on two sets of centrifuge model tests of wind turbines in dry sand and saturated sand subjected to earthquake sequences.The wind turbine system is composed of a single pile foundation and a wind turbine.All tests were applied with liquefaction experiments and analysis projects(LEAP)waves to simplify the analysis.The objectives of the tests are to investigate:(1)the influence of earthquake history on the seismic response of wind turbines;(2)the influence of earthquake history on the dynamic pile-soil interaction;and(3)the influence of two different foundation types on the seismic response of wind turbines.The tests indicated that earthquake history has a significant influence on the natural frequency of the pile and the soil around the pile in the saturated sand,but has no obvious influence on the dry sand.The shear modulus of the soil and the acceleration amplification factor of the pile top in both tests increased and the maximum bending moment envelope of the single pile foundation shrunk.The stiffness of the p-y curve in saturated sand was increased by the earthquake history,while that in dry sand was not significantly affected. 展开更多
关键词 earthquake history effect wind turbine pile bending moment dry and saturated sand ground dynamic p-y curves
下载PDF
AlH分子10个Λ-S态和26个Ω态光谱性质的理论研究
16
作者 邢伟 李胜周 +5 位作者 孙金锋 曹旭 朱遵略 李文涛 李悦毅 白春旭 《物理学报》 SCIE EI CAS CSCD 北大核心 2023年第16期62-76,共15页
在修正了各种误差(自旋-轨道耦合效应、标量相对论效应、核价相关效应及基组截断)的基础上,本文利用内收缩的多参考组态相互作用(icMRCI)+Q方法计算了AlH分子10个L-S态和26个W态的势能曲线.利用包含自旋-轨道耦合效应的icMRCI/AV6Z*理... 在修正了各种误差(自旋-轨道耦合效应、标量相对论效应、核价相关效应及基组截断)的基础上,本文利用内收缩的多参考组态相互作用(icMRCI)+Q方法计算了AlH分子10个L-S态和26个W态的势能曲线.利用包含自旋-轨道耦合效应的icMRCI/AV6Z*理论计算了X^(1)∑_(0+)^(+),a^(3)П_(0+),a^(3)П_(1),a^(3)П_(2)和A^(1)П_(1)态之间的跃迁偶极矩.计算得到的光谱常数和跃迁数据与现有的实验值符合很好.研究发现:1)A^(1)П_(1)-X^(1)∑_(0+)^(+)(0,0),(0,1),斯坦Δv≠0,(0,2),(1,0),(1,1),(1,2),(1,8),(1,4)和(1,5)带Q(J″)支的跃迁比较强,随着J″的增大,Δv=0带的爱因斯坦A系数和振动分支比值逐渐减小,加权的吸收振子强度值逐渐增大;Δv≠0带的爱因斯坦A系数、振动分支比和加权的吸收振子强度值逐渐增大;2)A^П_(1),v'=0和1能级的辐射寿命随着J的增大而缓慢增大;3)AlH分子的A^(1)П_(1)(v'=0和1,J'=1,+)→X^(1)+∑_(0+)^(+)(v″=0-3,J″=1,-)跃迁满足双原子分子激光冷却的准则,即对角化分布的振动分支比,A^(1)П_(1)(v'=0和1,J′=1,+)态极短的辐射寿命,a^(3)П_(0+),a^(3)П_(1)和a^(3)П_(2)中间电子态不会对激光冷却产生干扰.因此,基于A^(1)П_(1)(v'=0和1,J'=1,+)←→X^(1)∑_(0+)^(+)(v″=0-3,J″=1,-)循环跃迁,本文提出了激光冷却AlH分子的可行性方案,冷却时使用四束可见光波段的泵浦激光就可以散射2.641×10^(4)个光子,这足以冷却到超冷温度,并且主跃迁的多普勒温度和回弹温度为μK量级. 展开更多
关键词 势能曲线 光谱常数 自旋-轨道耦合 跃迁偶极矩 跃迁数据
下载PDF
闽浙木拱廊桥榫卯节点受力性能研究
17
作者 张铮 张博恒 +1 位作者 李振 缪远 《林产工业》 北大核心 2023年第7期58-63,74,共7页
为研究闽浙木拱廊桥榫卯节点受力性能,本研究建立了廊桥节点有限元模型,并验证了建模方法合理性。研究对直榫节点与燕尾榫节点进行分析,考察了榫头长度、节点连接角度和苗杆直径对节点受力性能的影响。结果表明:随着连接角度、苗杆直径... 为研究闽浙木拱廊桥榫卯节点受力性能,本研究建立了廊桥节点有限元模型,并验证了建模方法合理性。研究对直榫节点与燕尾榫节点进行分析,考察了榫头长度、节点连接角度和苗杆直径对节点受力性能的影响。结果表明:随着连接角度、苗杆直径的增大,直榫节点的极限承载力变大,直榫节点的极限承载力随着榫长增加先增大后减小。榫长与苗杆直径的增大可提高直榫节点的初始转动刚度,其中榫长对直榫节点受力性能的影响最为显著。榫长、节点连接角度和苗杆直径增加均能提高燕尾榫节点的初始转动刚度和极限承载力。 展开更多
关键词 木拱廊桥 榫卯节点 弯矩-转角曲线 有限元分析 影响因素
下载PDF
膨胀土浸水前后单桩p-y曲线研究
18
作者 杨迪 江杰 侯凯文 《人民长江》 北大核心 2023年第1期170-176,共7页
为研究膨胀土地基中水平受荷桩浸水前后的承载性能,分别进行了浸水前后的水平受荷桩室内模型试验,探究了桩周土抗力(p)、桩的水平位移(y)和桩身弯矩的变化规律;分别建立了浸水前后水平受荷桩的p-y曲线计算公式,并通过模型试验验证了所... 为研究膨胀土地基中水平受荷桩浸水前后的承载性能,分别进行了浸水前后的水平受荷桩室内模型试验,探究了桩周土抗力(p)、桩的水平位移(y)和桩身弯矩的变化规律;分别建立了浸水前后水平受荷桩的p-y曲线计算公式,并通过模型试验验证了所提公式的正确性。研究表明:浸水前后的土抗力随着水平位移的增加而逐渐增大,最终趋于稳定;浸水前后桩身弯矩均是先增大后减小,最大值位置分别为埋深0.10 m(4D)和0.12 m(4.8D)附近,当水平荷载相同时,浸水后的桩身弯矩较浸水前的有所增大。 展开更多
关键词 水平受荷桩 P-Y曲线 膨胀土 桩身弯矩 桩周土抗力
下载PDF
大转动惯量缠绕机加减速曲线优化设计
19
作者 窦方健 邱清盈 +2 位作者 管成 邵锦杰 吴海峰 《工程设计学报》 CSCD 北大核心 2023年第4期503-511,共9页
针对大转动惯量碳纤维缠绕机的加速和减速阶段运行不平稳、传动件易失效破坏等问题,提出了一种基于改进型Sigmoid加减速曲线的主轴运行曲线优化方案。首先,利用五次多项式对传统Sigmoid加减速曲线的跃变处进行补偿,以约束曲线起始点、... 针对大转动惯量碳纤维缠绕机的加速和减速阶段运行不平稳、传动件易失效破坏等问题,提出了一种基于改进型Sigmoid加减速曲线的主轴运行曲线优化方案。首先,利用五次多项式对传统Sigmoid加减速曲线的跃变处进行补偿,以约束曲线起始点、衔接点、终止点的速度、加速度和急动度(加加速度)。然后,基于改进曲线的速度与加速度函数建立缠绕机的负载扭矩、电机输出功率、主轴强度与刚度以及缠绕圈数的数学模型,并以各阶段运行时长为设计变量、以电机最大输出功率最小和总运行时长最短为优化目标对曲线进行多目标优化,根据缠绕圈数、传动件强度与刚度等的约束条件,利用多目标遗传算法NSGA-Ⅱ(non-dominated sorting genetic algorithm-Ⅱ,非支配排序遗传算法-Ⅱ)求解模型的非支配解集,并利用比重选取函数选择最优解。最后,通过AMESim-ADAMS联合仿真对比加减速曲线优化前后缠绕机的运行效果。结果表明:优化后缠绕机的总运行时长、最大加速度、最大负载扭矩和最大输出功率分别降低了41.7%,75.8%,75.5%和72.8%,且主轴的运行曲线更加平滑,验证了优化方案的可行性。研究结果为大转动惯量旋转设备的运行不平稳或传动件失效问题提供了一种新的解决思路。 展开更多
关键词 大转动惯量 缠绕机 加减速曲线 多目标优化 遗传算法
下载PDF
木结构钢销-短钢梁刚性连接弯矩-转角曲线简化计算方法
20
作者 连狄远 舒云峰 +3 位作者 黄浩 陶相宇 杨洋 张洋 《建筑结构》 北大核心 2023年第S01期1956-1963,共8页
结合已有研究成果及国外规范的建议,对木结构钢销-短钢梁刚性连接节点提出了设计和构造建议,并针对该类节点连接提出了相应的弯矩-转角(M-φ)曲线形式及弹性阶段节点刚度的简化计算方法;通过有限元数值模拟与理论推导结果的对比,证明了... 结合已有研究成果及国外规范的建议,对木结构钢销-短钢梁刚性连接节点提出了设计和构造建议,并针对该类节点连接提出了相应的弯矩-转角(M-φ)曲线形式及弹性阶段节点刚度的简化计算方法;通过有限元数值模拟与理论推导结果的对比,证明了该方法的正确性,且节点能够有效地传递截面的剪力和弯矩,满足刚性节点的要求;该方法计算简单,实操性强,为现代木结构设计提供了一种新的思路。 展开更多
关键词 木结构 刚性连接 弯矩-转角曲线 节点刚度 有限元分析
下载PDF
上一页 1 2 19 下一页 到第
使用帮助 返回顶部