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《中国测试》2016,(5):6-10
双相机工业摄影测量系统的广泛应用使其测量性能越来越受到关注,如何准确合理地评价系统的测量性能,并制定相应检定规范是目前亟待解决的问题。针对双相机系统测量性能的测试问题提出一套系统的方法:首先对双相机系统的摄影距离和基线长度等结构参数进行实验,并选择最佳参数进行系统的测量性能测试;然后对双相机的测量重复性、三维坐标测量准确度与长度测量准确度进行测评;最后通过以上3个评价指标对双相机系统测量性能进行总体分析与评价。该方法测得某型双相机的自身测量重复性为0.027 mm,三维坐标测量准确度为0.060 mm,长度测量准确度为0.062 mm。据此推荐用测量重复性、三维坐标测量准确度、长度测量准确度3个指标对系统进行评价。 相似文献
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高平 《中国新技术新产品》2023,(19):105-107
为解决当前不动产测量精度低的问题,该文采用倾斜摄影测量技术,并研究应用效果。在测量前完成各项准备工作,通过制作倾斜摄影测量无人机航线与像控点布设、像控点测量和不动产测量模型实现测量,并展示测量结果。将该方法应用于实际并进行评价,得出结论,新的测量方法其测量精度更高,测量思路在不动产测绘中也更具有可行性。 相似文献
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《中国新技术新产品》2020,(1)
随着科学技术的不断发展,以无人机为载体的航空摄影技术也得到了极大发展,倾斜摄影测量技术在测绘领域得到了广泛应用,无人机航测技术具有高分辨率、高几何精度、操作灵活、低成本的特点,已成为传统航空摄影测量技术的有效补充和延伸。该文结合工程实例,阐述了无人机倾斜摄影测量技术与传统测量技术相比的优势,分析了无人机倾斜摄影测量技术的操作原理以及应用,并对这项技术的未来发展进行展望。 相似文献
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调频源调频失真的测量牟能文,刘光复(辽宁锦西38610部队海军计量站,125000)本文对本刊1993年第1期“调频源调频解调失真的测量”一文作进一步讨论。一、调频失真与调频解调失真的关系在调频源调频过程中,由于使用非线性器件进行调频(目前多数采用变... 相似文献
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卢阳 《中国新技术新产品》2023,(10):22-24
当利用传统针孔相机进行摄影测量时,会存在视场较窄的限制。全景相机可以解决传统针孔相机视场有限的问题,使用全景影像进行摄影测量可以提高制图的效率。该文选用GoPro Hero4相机进行摄影测量,首先,对图像进行拼接,形成全景影像。其次,建立全景影像的共同投影中心、物点共线方程。再次,采用光束法平差,解算全景影像的外方位元素和物方空间坐标。最后,通过试验验证该方法的精度,在有良好控制点的条件下,该方法的测量精度高于6 cm。 相似文献
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冯哲 《中国新技术新产品》2023,(9):93-95
随着无人机技术、高精度定位等测量技术的快速发展,倾斜摄影测量已逐渐应用于地形图测绘中。该文通过结合湖南某地项目实例,采用无人机倾斜摄影技术方法测绘1∶500地形图,并对技术流程和地形图成果精度进行了验证分析。结果表明,利用该技术测绘1∶500地形图成果精度,完全满足相关规范要求,且测绘效率高,大大地节约成本,为地形图的快速更新,增强现势性等方面提供了很好的解决方案。 相似文献
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An integral method is investigated and developed in the current work. The effects of the parameters of inlet distortions
on the trend of downstream flow feature in compressor are simulated. Other than the drag-to-lift ratio of the blade and the
inlet incidence angle, it is found that the distorted inlet velocity is another essential parameter to control the distortion
in propagation. Based on this study, a novel critical distortion line and corresponding critical distortion factor are proposed
to express the effect of the two essential inlet parameters on the propagation of distortion, namely, the inlet incidence
angle and the distorted inlet velocity. From the viewpoint of compressor efficiency, the propagation of inlet flow distortion
is further described by a compressor critical performance and its critical characteristic. The results present a useful physical
insight to an axial flow compressor behavior and asymptotic behavior of the propagation of inlet distortion, and confirm the
active role of compressor in determining the velocity distribution when compressor responds to an inlet flow distortion.
Received: 20 December 2001 / Accepted: 21 August 2002
The authors would like to thank HQ RSAF for permission to publish this work, their financial support and encouragement. The
first author wants to acknowledge Prof. Frank Marble of California Institute of Technology, for bringing the problem to the
author's attention and for his helpful discussion. 相似文献
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范尔建 《中国材料科技与设备》2014,(1):64-68
本文结合攀钢2030连退退火炉机组,对炉内带钢纠偏系统控制原理和系统组成进行了分析,并对其各组成部分建立了相关的数学模型,为后续对带钢在炉内的高精度的跑偏控制提供了实用理论和模型方法。 相似文献
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通过建立二维有限元模型, 研究了Z-pinning增强工艺过程中Pin针的嵌入对预成型件纤维变形区域的改变, 定量表征了工艺引起的基体富集区的形状和大小, 以及局部纤维方向变化和纤维含量非均匀分布的特征参数, 得到纤维非均匀分布的规律。在此基础上, 模拟了不同直径的Pin针对层合板面内微观结构的影响规律。结果表明: Pin针直径的改变对基体富集区的影响较大; 局部纤维偏转角和纤维体积含量随着Pin针直径的增大而增大, 但其最大值变化不明显。 相似文献
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FEM prediction of buckling distortion induced by welding in thin plate panel structures 总被引:1,自引:0,他引:1
Welding distortion generated during assembly process has a strongly nonlinear feature, which includes material nonlinearity, geometric nonlinearity, and contact nonlinearity. In order to obtain a precise prediction of welding distortion, these nonlinear phenomena should be carefully considered. In this study, firstly, a prediction method of welding distortion, which combines thermo-elastic-plastic finite element method (FEM) and large deformation elastic FEM based on inherent strain theory and interface element method, was developed. Secondly, the inherent deformations of two typical weld joints involved in a large thin plate panel structure were calculated using the thermo-elastic-plastic FEM and their characteristics were also examined. Thirdly, using the developed elastic FEM and the inherent deformations, the usefulness of the proposed elastic FEM was demonstrated through the prediction of welding distortion in the large thin plate panel structures. Finally, the influences of heat input, welding procedure, welding sequence, thickness of plate, and spacing between the stiffeners on buckling propensity were investigated. The numerical simulation method developed in this study not only can be used to predict welding distortion in manufacturing stage but also can be employed in design or planning stage. 相似文献
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集装箱号的快速记录对于码头、港口业务至关重要.由于相机拍摄的图像常伴有严重的畸变,极大影响了字符识别算法的准确性,因此需要在识别之前对图像进行矫正.本文提出了一种快速有效地对存在畸变的集装箱号图像进行矫正的方法.首先应用基于MSER的图像分割算法对集装箱箱号区域进行检测,确定矫正的特征区域;然后根据低秩模型利用LADMAP*以及初始值热启动的方法来降低算法复杂度并矫正图像;最后,结合图像低秩和矫正前后的变换率优化算法的收敛条件,经过多次迭代后得到最终的矫正结果.实验结果表明,该方法不仅能对集装箱号进行较好的矫正,而且算法也具有稳健性. 相似文献
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Jun Yu Xin LinLiang Ma Junjie WangXingling Fu Jing ChenWeidong Huang 《Materials Science and Engineering: A》2011,528(3):1094-1104
Present work applied a kind of new deposition pattern, fractal deposition pattern, in the LSF process. The influences of different depositing patterns (fractal, offset and raster) on the parts’ deformation, interior quality and mechanical properties are also investigated. The finite element method (FEM) simulation results show that the offsetout (the offset from the outside to the inside) and fractal deposition patterns generate the temperature distribution with the circular and eccentric circle symmetry at the end of deposition process, respectively. There are smaller temperature gradients using these two kinds of deposition patterns than those by the raster and offsetin (the offset from the inside to the outside) deposition patterns. It is also found that the magnitude of the transient temperature gradient has a critical effect on part distortion during LSF process. The fractal deposition pattern generates the smallest parts’ deformation, followed by offsetout. The parts interior quality investigation with fractal and offsetout deposition patterns shows that the overlap should be increased to 50% to avoid pore defects. Moreover, we find that adopting arc path instead of square path at the corner locations and “semi-spot vibration” strategy for the offset and fractal deposition patterns respectively can produce better LSFed parts’ quality. 相似文献
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从部件模型和系统模型两个方面分析和总结了国内外制冷系统的建模研究及实际应用状况,认为将制冷系统模型与其它子系统模型相结合的方法能更好地实现空调系统性能优化的目标。 相似文献
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柱面实像投影是飞机训练模拟器视景系统采用的主要投影方式之一,可以得到很大的观察视野,但是不可避免地会产生非线性失真。根据具体的工程背景,针对大视场角的柱面实像投影的非线性失真,分析了其产生的原因,并设计了投影仪的离轴安装方案,从而提出了基于预失真的柱面投影非线性失真校正算法。实际的校正结果表明,采用预失真的方法进行柱面非线性失真校正,是一种行之有效的方法。通过相应的数据结构设计,保证了程序执行的实时性。 相似文献