共查询到20条相似文献,搜索用时 78 毫秒
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目前直角坐标系下空间直线度偏差评价尚未形成统一的方法,针对此问题,提出了基于点特征的直角坐标系空间直线度偏差评价方法。利用空间直线度偏差测量模型与点特征间的关系,以直角坐标系下空间直线度测量方法为基础,建立空间直线度偏差评价数学模型。在截面测量法的基础上,建立空间直线度偏差测量模型。基于空间任意对称二次曲线数学方程,构建最小二乘测量截面轮廓曲线,解决被测截面轮廓中心获取的问题。根据模型点特征关系,最终实现对空间直线度偏差的准确评价。通过实际测试验证了所提出方法的合理性与准确性,为推动空间直线度精密测量技术发展提供了有力支撑。 相似文献
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基于静态压缩实验、广义胡克定律和应变能密度推导了描述橡胶超弹性的本构关系,进而获得了橡胶隔振器静态刚度模型;在此基础上,提出基于动态激振实验的动态刚度模型,该模型由橡胶隔振器静态刚度、位移系数和频率系数组成。在此基础上,对单自由度质量-隔振器系统进行数值仿真和实验测试,二者获得的系统的固有频率基本吻合,验证了所提出的橡胶隔振器动力学模型的正确性。研究结果为获得橡胶隔振器静、动态刚度模型提供了简洁、实用的思路,并为研究含有隔振器的动力系统的动力学特性提供了理论基础。 相似文献
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综合考虑了车流随机性和桥面等级退化等因素,提出了一种新的分析模型,该模型能分析在役桥梁不同服役期间在交通荷载及风耦合作用下的桥梁动态响应。基于已有车辆模型,建立了一个可考虑车辆纵向振动的18自由度空间车辆模型,考虑邻近车辆影响基础之上的改进CA(Cellular Automation-元胞自动机)模型和桥面退化模型,并引入等效车轮荷载的方法,通过风、桥梁和车辆相互作用关系,建立了风-车流-桥梁系统的耦合振动分析模型。数值计算表明:该文所提出的方法能够合理的模拟风-车流-桥梁系统的耦合振动。 相似文献
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基于CAMSHIFT算法和形态学的人手动态分割 总被引:1,自引:0,他引:1
动态图象分割是计算机视觉分析中一个重要和困难的任务。该文讨论了一种基于CAMSHIFT算法和形态学的动态跟踪分割。首先把采集到的图象由RGB色彩空间转换到HSV色彩空间,因为肤色对HSV色彩空间的H色调具有恒常性。其后在HSV颜色空间建立肤色直方图模型,确定肤色概率度,运用CAMSHIFT算法对人手动态跟踪,然后运用形态学重构闭运算去除空洞和噪声。实验证明该方法能够有效的实现了人手的动态分割。 相似文献
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精确的有限元模型对于结构动态响应预测以及动态设计至关重要。利用模态试验数据,针对高速列车结构特点与动力学特性,深入分析设计空间方法选择、修正参数选择、响应面拟合和参数修正等关键问题,运用动力修正相关理论提出适合高速列车的基于试验模态车体动力学有限元模型修正方法。并运用该方法,采用模态试验数据修正高速列车车体结构的模态分析模型,频率的计算结果与试验结果的最大误差为-0.260 9%。研究验证基于模态试验数据高速列车车体动力学有限元模型的响应面修正方法的有效性。 相似文献
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平面应变情况下多重势面模型与邓肯-张模型的比较 总被引:3,自引:0,他引:3
多重势面理论给岩土材料的本构关系研究指出了更开阔的数学背景。由此建立的土的本构模型可以无需推求塑性势函数和屈服函数,且其所能表述的本构关系比通常的塑性位势理论更为广泛。基于应变空间的多重势面模型具有参数求取简单、程序易于实现的特点,更具有实用性。在这篇论文中,利用所开发的有限元程序NM02就平面应变情况对多重势面模型和邓肯-张m-E模型计算成果进行对比分析,其中多重势面模型参数与m-E模型参数完全相同。有关计算分析成果对进一步研究多重势面模型是很有意义的。 相似文献
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一种从功能模型到动态模型的映射机制 总被引:1,自引:0,他引:1
CIMS多方位(视图)模型的一致性问题是CIMS建模方法学中的研究重点。本文提出了一种从基于IDEF0的功能模型到基于Petri-Net的动态模型的映射机制,为研究模型一致性问题提供了一种行之有效的途径。 相似文献
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One characteristic of the two-carrier model is that two types of carriers with different masses can coexist in transporting the supercurrent in a cuprate superconductor. We employ the two-carrier model to explain the experimental evidence that in the YBCO system, the signs of the charged carriers along thea-b plane andc-axis are opposite. We also analyze the relationship between the superconductor-semiconductor composite model and the two-carrier model. 相似文献
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A stochastic catastrophe model using two-fluid model parameters to investigate traffic safety on urban arterials 总被引:1,自引:0,他引:1
During the last few decades, the two-fluid model and its two parameters have been widely used in transportation engineering to represent the quality of operational traffic service on urban arterials. Catastrophe models have also often been used to describe traffic flow on freeway sections. This paper demonstrates the possibility of developing a pro-active network screening tool that estimates the crash rate using a stochastic cusp catastrophe model with the two-fluid model's parameters as inputs. The paper investigates the analogy in logic behind the two-fluid model and the catastrophe model using straightforward graphical illustrations. The paper then demonstrates the application of two-fluid model parameters to a stochastic catastrophe model designed to estimate the level of safety on urban arterials. Current road safety management, including network safety screening, is post-active rather than pro-active in the sense that an existing hotspot must be identified before a safety improvement program can be implemented. This paper suggests that a stochastic catastrophe model can help us to become more pro-active by helping us to identify urban arterials that currently show an acceptable level of safety, but which are vulnerable to turning into crash hotspots. We would then be able to implement remedial actions before hotspots develop. 相似文献
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Calculations in Green's function technique apply an interpolation ansatz for the self-energy between the weak and strong coupling regime to the doped case of correlated models. The DOS of the one-band Hubbard model with the Kondo-like peak at the chemical potential is in good agreement with recent numerical results. In the doped three-band model a singlet correlation band from copper and oxygen states appears at the Fermi surface with dispersion similar to the free bands but with strongly renormalized bandwidth. The Fermi surface changes from closed hole type to closed electron type upon doping and is perfectly nested for some doping valuen1.25. 相似文献
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冰激桥墩振动室内模型试验研究 总被引:1,自引:0,他引:1
鉴于模型试验是研究冰激结构振动特点和机理的一种非常有效的方法和手段,本文以某桥墩为背景,通过一修正的动冰力模型试验相似律设计了一桥墩模型,应用DUT-1模型冰,模拟了不同冰速下冰-桥墩动力相互作用过程,并实测了冰力和桥墩各测点处的响应。进而得到了一些有价值的试验现象和试验结果,这将为寒冷区域实际冰工程的建设提供一定的借鉴意义,同时可为冰激结构振动的发展提供探索性的意义,也能够在一定程度上完善室内冰激振动模型试验。 相似文献
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A computer model for regional ground water resource evaluation, based on the leaky aquifer concept, is presented for the Vedavati
basin which is a crystalline hard rock area of 24,200 km2 in Peninsular India. The model can handle nonhomogeneity, anisotropy, varied pumping, rainfall and river stages. The model
is calibrated based on regional water level observations for one year. The calibrated model is used to determine the distribution
of safe yield, overexploited regions and regions of maximum potential over the basin. Regions which are most affected by drought
conditions are also identified. 相似文献
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L. Mihaela Paun Mitchel J. Colebank Mette S. Olufsen Nicholas A. Hill Dirk Husmeier 《Journal of the Royal Society Interface》2020,17(173)
This study uses Bayesian inference to quantify the uncertainty of model parameters and haemodynamic predictions in a one-dimensional pulmonary circulation model based on an integration of mouse haemodynamic and micro-computed tomography imaging data. We emphasize an often neglected, though important source of uncertainty: in the mathematical model form due to the discrepancy between the model and the reality, and in the measurements due to the wrong noise model (jointly called ‘model mismatch’). We demonstrate that minimizing the mean squared error between the measured and the predicted data (the conventional method) in the presence of model mismatch leads to biased and overly confident parameter estimates and haemodynamic predictions. We show that our proposed method allowing for model mismatch, which we represent with Gaussian processes, corrects the bias. Additionally, we compare a linear and a nonlinear wall model, as well as models with different vessel stiffness relations. We use formal model selection analysis based on the Watanabe Akaike information criterion to select the model that best predicts the pulmonary haemodynamics. Results show that the nonlinear pressure–area relationship with stiffness dependent on the unstressed radius predicts best the data measured in a control mouse. 相似文献
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通过假设检验验证了Weibull及Gauss分布模型对玄武岩纤维丝束强度统计分析的适用性,并用2种分布模型对BF-CSH-01、BF-CMD-02和BF-CAH-01 等3种纤维不同长度丝束的拉伸强度分布进行了统计分析。当纤维种类和试样长度变化时,采用2种模型统计的丝束强度的变化规律一致,即3种纤维中BF-CSH-01强度最高,BF-CMD-02的强度分散性最小;同种纤维中,随着试样长度的增加,丝束强度下降,强度分散性减小。2种分布模型相比,采用Weibull 模型计算的丝束强度略高于 Gauss模型,但强度分散性稍大。 相似文献