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1.
The beam element in FLAC3D can be used to simulate the supporting arch in a tunnel. However, this approach has the shortcoming of its constitutive model, and the bearing capacity and surrounding rock supporting effect of the arch model will be significantly exaggerated. To simulate the supporting arch in tunnel engineering well, a new approach is proposed by improving the beam element. The yield criterion of the beam element subjected to compression-bending loads is established based on the now-available bearing capacity formulas of some typical compression-bending sections. In addition, the yield criterion is embedded in the FLAC3D main program by using the FISH language, and the modification of the beam model and the yielding failure simulation of the supporting arch are finally implemented. Compression-bending tests and roadway tunnel arch support example analysis were performed. The results are as follows: (1) the modified model showed the dependence of the bending moment and axial force on the yielding action of the beam element under compression-bending loads; (2) the implementation program is effective and sensitive; (3) the computing deviation caused by the shortcomings of the original beam element model was effectively suppressed, the mechanical behavior and surrounding rock supporting laws exhibited by the arch model were much closer to reality, and the calculation accuracy and design reliability were improved by the new simulation approach. 相似文献
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无刷双馈电机（BDFM）作为一种新型电机,兼有绕线式转子异步电机和同步电机的优良特性,尤其适合于变速恒频发电领域,通过分析无刷双馈电机的结构及工作原理,建立了基于转子速坐标系的d-q轴无刷双馈电机数学模型,根据所得的数学模型,对无刷双馈电机的各种运行方式进行了仿真分析,采用MATLAB/Simulink进行了计算机仿真研究,得出了各种运行方式下的仿真波形,仿真结果验证了数学模型的正确性和可行性,并得到了一些有益的结论. 相似文献
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在对出行目的地空间分布特点进行分析的基础上,提出了减少选择枝个数的目的地小区分段抽样策略,该策略的应用减少了仿真的计算量.采用该抽样策略建立了基于贝叶斯理论的出行者出行方式和目的地联合选择模型.通过对该模型进行仿真计算,结果表明出行方式和目的地的联合选择模型能够有效地模拟出行者的行为选择.而且,联合选择模型的预测精度明显高于重力模型.因此,在分析出行者行为选择方面采用出行方式和目的地的联合选择模型是一种有效的方法. 相似文献
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An approach of position sensorless control for permanent magnet synchronous motor （ PMSM ） is put forward based on a sliding mode observer. The mathematical model of PMSM in a stationary αβ reference frame is adopted, and the system is controlled by the digital signal processor （ DSP; TMS320LF2407 according to the control achieve closed loop operation of the motor, the stator theory of sliding mode observer. In order to magnetic field should be vertical with the rotor magnetic field and be synchronous with rotor rotating, so the position and speed of PMSM is estimated in real time and the estimated position is modified continuously. The simulation results indicate that the proposed observer has high precision is more robust to the parametric variation and load in estimation of PMSM position and speed, and torque disturbance. 相似文献
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Based on the characteristics of an L-shaped column composed of concrete-filled square steel tubes, the axial compression experiment and nonlinear finite element analysis were carried out to study the mechanical property of the L-shaped column. The load-displacement curve for the L-shaped column, the deflection and load-strain curves for the mono columns were obtained by the axial compression experiment. The results show that the L-shaped column exhibits a flexural-torsional buckling failure mode. The numerical simulation by the finite element analysis shows that the bearing capacity and failure mode are in accordance with those of the axial compression experiment and the feasi- bility of the finite element analysis is proved. For the calculation of the bearing capacity of the L-shaped column com- posed of concrete-filled square steel tubes, an analytical method is proposed based on the theory of the elastic stability and spatial truss model. The results of the analytical method are in good agreement with those of the axial compression experiment and the finite element analysis. 相似文献
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针对一种新型混联式汽车电泳涂装输送机构控制方法存在收敛时间较长问题,提出一种有限时间收敛滑模控制方法。首先采用解析法对机构进行运动学分析,并基于拉格朗日法建立输送机构动力学模型;提出一种快速终端滑模有限时间收敛控制方法,实现新型混联式输送机构控制的有限时间收敛;然后设计有限时间滑模观测器,实时观测被控对象模型中的不确定参数以及外部随机干扰并加以前馈补偿,以进一步提高系统鲁棒性,同时解决快速终端滑模控制存在的抖振问题;最后运用Lyapunov稳定性理论证明该控制方法的稳定性,利用MATLAB对控制方法进行仿真,并将其应用于新型混联式输送机构样机进行实验,结果表明该控制器具有跟踪误差小、稳态精度高、响应速度快、鲁棒性好的特点。 相似文献
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基于采用对称翼型的小展弦比三角形机翼模型,对其在亚音速状态和超音速状态时的升力特性、阻力特性、升阻比特性、稳定性特性进行了理论计算分析。并针对该模型进行数值模拟,分析其超音速流场特性,与理论分析结果进行对比,发现相差不大。得出结论:该翼型机翼在飞机巡航速度为Ma=2时气动性能较好。 相似文献
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为了获取某四驱汽车防滑差速器壳体的固有振动特性和验证所建有限元模型的正确性,以某四驱汽车防滑差速器壳体为研究对象,首先基于Abaqus软件对其进行模态仿真分析,得到了防滑差速器前6阶固有特性参数及其振型;然后运用锤击实验对防滑差速器进行模态分析实验,测取其振动情况;最后将两种方法获取的差速器壳体前6阶振型及振动频率进行对比。结果发现两种方法获取的各阶振型基本一致,固有频率误差在5%以内。这种以模态仿真分析为前提,模态实验为补充,仿真结果与实验结果相对比的分析方法有效地验证了有限元模型的正确性,为防滑差速器的有限元分析提供了有效的参考依据。 相似文献
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基于离散单元法建立了圆柱形颗粒阻尼器的仿真模型,研究了阻尼器内颗粒在不同激振条件下的运动形态及其能量耗散大小。为了获取两者之间的定量关系,应用基于网格搜索法(GS)的支持向量机(SVM)建立了颗粒运动形态的分类预测模型及其能量损耗的回归预测模型,对颗粒运动形态的分布及其能量损耗的大小进行了预测,并通过仿真进行了验证。结果表明:基于GS方法优化的SVM能够建立一个预测准确度很高、推广泛化能力很强的分类和回归预测模型,该预测模型不仅能够很好地揭示颗粒系统在不同运动形态下的能量耗散的变化规律,而且还能在较大的激振条件范围内确定系统能量耗散最大值及对应的运动形态。 相似文献
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杨洋 《江西电力职业技术学院学报》2009,22(2)
针对配电网可靠性的特点,在充分考虑可靠性指标的历史变化趋势并顾及各种相关因素对可靠性指标影响的情况下,分别建立了基于历史统计数据的横向预测模型和考虑相关因素影响的纵向预测模型,形成了灰色组合预测模型,充分发挥了灰色预测模型所需样本小、精确度高的优点。该模型为配电网可靠性指标的预测提供了新的实用方法,同时,其结果可以为配电网的规划设计、运行和维护提供新的依据。通过对某地区配电网可靠性统计数据的实例分析,证明了该方法的有效性。 相似文献
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利用有限元法求解了二维对流扩散方程边值问题,得到了相应的误差分析,并进行了数值模拟。模拟结果表明该方法求得的数值解有较高的精度和较快的运行速度。 相似文献
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ZHONG Yi-feng WANG Rui YING Xue-gan CHEN Huai 《重庆大学学报(英文版)》2006,5(4):218-222
1 Introduction When librating with small amplitude, the discrete linearization freedom vibration equation of a structure is [1]: [m ] {x } [k ]{ x } = {0 } (1) The relevant vibration characteristic question is ([ k ] ? p 2[ m] ){φ } = {0} (2) where [m]… 相似文献
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以可编程控制器为核心开发了应用于电力系统动态模拟试验的短路故障模拟控制系统。该系统由SIEMENS S7-200 PLC为核心的短路故障模拟控制器、上位PC机编程-控制平台和一次模拟控制设备三部分构成。系统可以实现模拟一次设备现场的就地控制和主控制室后台控制;能够进行各种类型的金属性和非金属性短路模拟;可以实现短路发展及其清除过程的任意时序设置。投入使用一年多的运行情况表明,该系统设计合理、结构紧凑、功能完善、使用操作简便、运行可靠性高,是电力系统动态模拟实验的重要辅助设备。 相似文献
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利用有限差分法求解波动方程边值问题,得到了相应的稳定性分析,并进行了数值模拟.模拟结果表明;该方法求得的数值解有较高的精度和较快的运行速度. 相似文献
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Laura Castro-Schilo Kevin J. Grimm Keith F. Widaman 《Structural equation modeling》2016,23(6):798-818
We introduce an approach for ensuring empirical identification of the correlated trait–correlated method (CT–CM) model under a variety of conditions. A set of models are referred to as augmented correlated trait–correlated method (ACT–CM) models because they are based on systematically augmenting the multitrait–multimethod matrix put forth by Campbell and Fiske (1959). We show results from a Monte Carlo simulation study in which data characteristics lead to an empirically underidentified standard CT–CM model, but a well-identified fully augmented correlated trait–correlated method (FACT–CM) model. This improved identification occurs even for a model in which equality constraints are imposed on loadings on each trait factor and loadings on each method factor—a specific case shown to lead to an empirically underidentified CT–CM model. 相似文献
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比较了应用于传感器网络声源追踪定位的3种模型,其中信号源能量模型对数据处理简单,更利于节省能量。针对现有基于信号源能量模型的算法的不足,给出了一种全新的算法—梯度迭代算法,并通过仿真实验证明了其在追踪的精确度和速度方面具有明显的优势。 相似文献
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郑海鹰 《温州大学学报(社会科学版)》2008,(2):38-42
基于元件的定数截尾寿命试验数据和切换开关的成败型试验数据,对两部件温贮备系统可靠性的置信限进行了研究,分别得到了系统精确和近似fiducial置信限模型,最后给出随机模拟例子并讨论了置信限的精度． 相似文献
20.
评价既有桥梁可靠性的FNM法(英文) 总被引：1，自引：0，他引：1
结合现行规范及钢管混凝土拱桥的受力特点,给出钢管混凝土拱桥安全-中介-失效三级工作模式的确定准则.据此计算结构的损伤概率与失效概率及对应的可靠度指标,建立可靠度指标与三级工作模式的直接关系.基于三级工作模式,提出评估在役桥梁结构可靠度的有限元-神经网络-蒙特卡罗(FNM)法.根据时变可靠度理论,将结构继续服役期离散化,随机抽样生成蒙特卡罗法所需的最少样本,由随机有限元法计算训练样本,用神经网络扩展训练样本,最后通过蒙特卡罗法计算失效概率和损伤概率,得到结构时变可靠度,判断其工作状态.运用该方法对一座建成10年,主跨83.6 m的钢管混凝土拱桥进行分析,结果表明,该桥主拱处于安全状态,这一结论与实际情况相符.说明FNM法对于评价在役桥梁的可靠性是可行的. 相似文献