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首先根据模型黄河的特点,阐述了DPIV技术测量流速的基本原理。然后,讲解了作者利用DPIV技术,设计的模型黄河流速测量系统的组成。最后,针对在模型实验ee,具体的数据进行了分析,结果表明DPIV技术能快速有效地测量出表面流场的速度矢量分布,精度高、鲁棒性好,符合大型河工模型表面流场的速度测量要求。 相似文献
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对柔性坐标测量机的测量空间进行了定义,建立了测量模型,采用蒙特卡罗(Monte Carlo)理论生成了6个关节变量的伪随机数,并利用坐标测量机的测量模型进行了仿真.仿真结果表明,该测量空间的形状为一完整的球体,没有"空腔",证明了柔性坐标测量机几何结构尺寸的设计符合要求,并有助于进一步研究该测量机空间误差分布规律. 相似文献
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提出了一种在线测量球团密度的新方法.该方法以模糊技术为基础,综合考虑制团过程各因素对球团密度的影响,建立起球团密度的软测量模型.在软测量模型中,采用T-S模糊模型描述球团密度变化的非线性过程,并提出了一种改进的模型辨识算法,利用减法聚类法确定合适的聚类组数目,并用实数编码的遗传算法优化全局参数,从而获得了结构简单、具有较高精度的模糊软测量模型.根据此方法,设计了测量装置,并进行了现场试验,试验结果表明软测量模型输出与实验室测量值基本一致,平均误差较低.该方法较大地提高了制团的生产效率,为球团密度的最优控制奠定了基础. 相似文献
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设计了一种结构简单、对加工工艺要求较低的双锥流量计,并用于气液两相流参数的测量.提取双锥流量计的差压波动信号的特征值,采用无量纲分析方法建立分相含率的测量模型,通过优化方法获得局部最佳的模型参数.在气液两相流实验装置上开展了实验研究.结果表明,所建立的分相含率测量模型可在一定的空隙率范围内对气液两相流含气率进行有效的测量. 相似文献
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基于光泽分析的分光测色仪SCI误差修正模型 总被引:1,自引:0,他引:1
在对相同材质,不同光泽的物体表面进行颜色测量时,为了去除表面光泽对颜色测量产生的影响,多选择漫射照明、8?观察角、包含镜面反射光的照明观测条件。在理想情况下,由于积分球对照明光线的匀化,测量结果不会受到材料表面光泽的影响。但是在实际仪器结构设计中,由于测量结构设计的限制导致相同光谱反射率,不同表面光泽的测试样品颜色测量结果不同。文章从理论上分析了漫射照明、8?观察角、包含镜面反射光的照明观测条件下不同光泽材料表面测量产生误差的原因,设计了一种可以同时测量颜色数据和光泽数据的测量结构,提出了一种根据被测材料表面光泽数据对SCI测量数据进行修正的矫正模型,并设计相关实验进行验证。实验结果证明,应用该矫正模型对测量结构进行修正可以显著减小该测量误差。 相似文献
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为了研究球形弹簧摆对输电塔结构的风致振动控制效果,通过分段等刚度梁单元建立输电塔简化模型。给出了空间梁系结构基于Timoshenko梁理论的单元内力计算公式,并应用有限质点法对简化模型及其与球形弹簧摆的耦合系统进行风致响应分析。一方面,球形弹簧摆由于内共振性质实现非线性能量阱,从而增加振动抑制频带的宽度,提高了鲁棒性;另一方面,球形弹簧摆和结构的非线性耦合,使得顺风向的振动能量部分转移到横风向,尽管增大了横风向响应,但是降低了结构的总体响应。计算结果表明球形弹簧摆减振效果非常好,当将其安装在除塔顶外的三个位置时,位移最大值和加速度均方根减振率分别为32.5%~41.7%和35.7%~65.2%。保持质量比和安装位置不变,验证了球形弹簧摆具有较宽的设计频带。使用球形弹簧摆可以显著减小位移标准差,有利于降低结构的疲劳损伤风险。 相似文献
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利用非线性动力有限元分析程序,对于半无限岩土介质中的洞室,研究了球面波在围岩中的传播特性和动态裂纹的产生过程,比较了球面波在毛洞和锚杆加固洞室围岩中的衰减规律和动态裂纹形态的差别。结果表明:围岩动态裂纹是自由面产生的反射拉伸波及其相互叠加以及加固区与未加固区相互错动剪切的综合作用造成的;球面波强度在毛洞围岩中的衰减速度比在加固洞室中的快;锚杆加固洞室的破坏程度比毛洞轻一些;将模拟所得加固洞室围岩破坏形态与相应模型试验的结果进行了比较,发现洞室破坏形态及规律较为一致,说明了数值分析结果是可信的。研究结果对球面波的认识和防护工程的加固设计具有较好的参考价值。 相似文献
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Mashimo T. Toyama S. Ishida H. 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2009,56(11):2514-2521
We present a mechanical design and implementation of spherical ultrasonic motor (SUSM) that is an actuator with multiple rotational degrees of freedom (multi-DOF). The motor is constructed of 3 annular stators and a spherical rotor and is much smaller and simpler than conventional multi-DOF mechanisms such as gimbals using servomotors. We designed a novel SUSM using experimental data from a single annular stator and a finite element method. The SUSM using a spherical rotor of diameter 20 mm without any reduction gear has demonstrated advantages of high responsiveness, good accuracy, and high torque at low speed. The dynamic implementation of SUSM was consistent with the driving model of SUSM based on a friction drive. 相似文献
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Off-axis aberrations of a wide-angle schematic eye model. 总被引:2,自引:0,他引:2
I Escudero-Sanz R Navarro 《Journal of the Optical Society of America. A, Optics, image science, and vision》1999,16(8):1881-1891
A schematic eye model based on anatomical data, which had been previously designed to reproduce image quality on axis, has been transformed into a wide-angle model by simply adding a spherical image surface that plays the role of the retina. This model captures the main features of the wide-angle optical design of the human eye with minimum complexity: four conic optical surfaces plus a spherical image surface. Seidel aberrations (spherical aberration, coma, astigmatism, field curvature, and distortion), longitudinal and transverse chromatic aberrations, and overall monochromatic spot diagrams have been computed for this eye model and for field angles ranging from 0 degree to 60 degrees by both finite and third-order ray tracing. The modulation transfer function for each field angle has been computed as well. In each case our results have been compared with average experimental data found in the literature, showing a reasonably good agreement. The agreement between the model and experimental data is better off axis, mainly at moderate (10 degrees-40 degrees) field angles, than on axis. The model has been applied to simulate a variety of experimental methods in which image aberrations are estimated from measurements taken in the object space. Our results suggest that for some types of aberration, these methods may yield biased estimates. 相似文献
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该文为分析海冰与锥体海洋平台的相互作用,采用离散元(DEM)-有限元(FEM)耦合方法建立冰激海洋平台结构的耦合模型。通过具有粘结-破碎性能的球体离散单元对海冰的漂移及破碎现象进行计算,海洋平台锥体部分采用平板型壳单元构造,其整体构架及锥体内部的加劲肋采用梁单元构造,即建立壳单元与梁单元组合的锥体海洋平台有限元模型。为提高DEM-FEM耦合算法的计算规模和效率,发展了离散单元与平板型壳单元接触算法及GPU并行环境下参数传递算法。基于此耦合模型分别讨论了平台结构的冰载荷、冰激振动以及锥体应力分布,并与相关实测数据进行对比,为寒区锥体海洋平台的结构设计提供有益的参考。 相似文献
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An optical design for spherical-grating monochromators for application to synchrotron radiation is presented. High spectral and spatial performance is obtained with a spherical variable-line-spaced grating coupled to a spherical mirror with its tangential plane coincident with the grating's equatorial plane. The monochromator works without an entrance slit in an off-Rowland configuration with a fixed entrance arm and demagnification on the exit slit. The law for groove-space variation of the grating compensates for the main spectral aberrations; spectral focusing in an extended energy range is ensured by a slight change in the exit arm with translations of the order of a few tens of millimeters. The inclusion of a spherical mirror ensures focusing on a plane perpendicular to the plane of spectral dispersion. The ultimate resolution is limited by the slope errors of a single spherical surface. The layout is applied to the design of a high-resolution monochromator for the 1000-250-eV region. 相似文献
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对于等离子体浸没离子注入(PIII)技术,球形靶鞘层尺度预测对真空室设计、批量处理研究等是十分有用的。但由于球形靶鞘层Child-Langmuir定律数学表达的非线性使得工程应用较为困难。本文对球形靶的鞘层尺度进行了数值求解、讨论了注入参数对鞘层尺度的影响。计算结果表明,鞘层厚度(包括离子阵鞘层和稳态鞘层)随球体半径或注入电压增加而增加,随等离子体密度增加而减小。但对于不同的参数区间,鞘层特性对参数的变化表现出不同的敏感性。当等离子体密度较高、注入电压较低时,稳态鞘层厚度对于靶体半径的变化极不敏感。相反鞘层厚度对靶体大小变化较为敏感。虽然平面靶与球形靶的离子阵鞘层尺度比值与等离子体密度及球体半径有关,但平面靶稳态鞘层尺度总是大于球形靶的。这对于实际的PIII应用具有重要的指导意义。 相似文献
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Abstract The design of an optical element profile with specified transmission function for a given incident wave is of fundamental concern in optical design. A well-known example is the design of an aspherical surface in order to realize a spherical phase-only transmission. Various wave-optical system design methods lead to transmission functions as a first step. Then, often the thin-element approximation is applied in a second step to obtain an element structure with the desired transmission. However, if the refraction at the optical interface cannot be neglected, the thin-element approximation is not valid. In this case, a higher version of the local plane-interface approximation can be used for the element structure design. An algorithm for this model is introduced and its characteristics are discussed for the example of a non-paraxial Gaussian-to-tophat beam shaping element. 相似文献