共查询到20条相似文献，搜索用时 406 毫秒
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本文主要根据控制点不同分布以及控制点选取个数的不同研究RTK测点点位精度所受到的影响,从而确定控制点选取原则。分别选取一个控制点、三个控制点以及四个控制点三种方案,而在这三种方案中又根据点位分布的不同分别选取直线型、不完全控制、完全控制三种点位选取方法。经精度评定,得出当控制点个数相同时,控制点完全分布时坐标转换的精度最高。控制点的选取一般采用完全分布。而当控制点个数不同时,控制点个数越多坐标转换精度越高。因此控制点的分布越均匀个数越多坐标转换的精度越高。 相似文献
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全站仪自由设站法可以方便、快速地测定临时控制点坐标,再从临时控制点测定各细部点位,此方法很好的解决了两点间不通视的问题。由于自由设站设站次数少且有多余观测,从理论上其精度有可靠的保证,能够满足建筑施工放样的精度要求。 相似文献
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本文研究在GPS-RTK测量时根据控制点点位不同的分布情况,进行坐标转换时对坐标精度的影响情况。并得出结论,控制点最好分布于控制区的两侧,且应均匀的分布。 相似文献
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以南康市龙华乡集贸商住小区修建性详细规划项目为例,研究一种控制点重新定位的方法。实验以精度较高的参照点为依据,将假定坐标系交会出的参照点转换到原坐标系,从而实现了控制点的重新定位。同时,主要通过该项目的实际情况,结合测角前方交会观测的角度,然后由新的控制点坐标计算出的参照点坐标与原始参照点坐标进行比较、分析,证明了该方法是切实可行的。 相似文献
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利用相临的两个已知等级测量控制点,通过在待定点上设置测站,测量出该待定点至相对较近等级控制点间的距离及该待定点至两个等级控制点方向间的水平角,可以求算出该待定点的坐标,其坐标中误差可以满足图根点(测站点)的精度要求。 相似文献
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在世界范围内,一个国家的工业综合实力往往是通过航空发动机的研发和加工技术水平来体现的。在航空发动机加工的过程中有效的保障加工质量,控制加工变形已经成为了航空发动机生产以及研发过程中的重要课题,对于航空事业的发展有非常积极的作用。在航空发动机生产过程中,叶片的生产工艺非常关键,不论是从叶片的加工精度以及叶片的加工质量上都有着非常严格的要求。由于航空发动机的叶片形状曲面较多,因此如何控制叶片的加工尺寸以及加工精度就成为了叶片加工过程中的重要环节。 相似文献
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GPS控制测量时,要联测一些国家或地方坐标系下的点作为起算点,但联测的这些起算点兼容性不好将影响整个网的精度,因此我们在把联测点加入控制网平差时应该对对其兼容性进行分析,剔除它们中兼容性不好的点,提高控制网精度.介绍了几种兼容性分析方法,总结出几点体会. 相似文献
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《Journal of The Franklin Institute》2023,360(8):5811-5831
Unmanned tractors are widely adopted in agricultural operations as autonomous driving technology progresses. The current path tracking control methods are limited by the unstructured farmland, the accuracy and anti-interference ability needed to be improved. This paper presents a novel adaptive second-order sliding mode (ASOSM) control method to tackle the aforementioned problems in practical implementation. First, we introduce a preview lateral offset model based on the preview kinematic and tractor dynamic model, which helps solve the under-actuated problem in path tracking. Then, the ASOSM controller is designed using the revamped adding a power integrator (API) and adaptive mechanism, which ensures that the sliding variable is converged to zero within the finite time. Meanwhile, the chattering problem in traditional sliding mode control is relieved. Finally, a high-fidelity and full-car model is established under Simulink/Carsim environment, and comparative simulations conrm the superiority of the designed control method. 相似文献
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A new method for obtaining reduced order models for single-input-single-output, continuous-time systems is presented. The proposed algorithm matches the transfer functions of the original and the reduced system at 2M points where M is the order of the reduced model. The location of these points depends on a parameter which can be selected to control the accuracy of the approximation and stability. Numerical examples and comparisons with other methods of model reduction are given. 相似文献
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《Journal of The Franklin Institute》2023,360(12):8704-8739
Indoor point cloud segmentation is necessary for many applications including object identification for indoor navigation, facility management and so on. In order to construct accurate segmentation system of indoor point cloud, this paper improves cloth simulation and uses it to control the segmentation of ceiling and floor. Simultaneously, we obtain the wall points according to the points’ density. We mainly introduce indoor objects control segmentation via clustering strategy. First, we generate the cutoff distance according to the angular resolution and scan distance. Second, we use exponential function to determine the local density. Third, the cluster center is determined according to the magnitude of product of local density and distance which are normalized. Finally, the points affiliated to a cluster are controlled one by one according to the distance between point and cluster center. Segmentation of objects is then realized based on the established clusters. Experiments indicate that the proposed algorithm achieves a competitive performance when compared with several state-of-the-art algorithms. The performance of the proposed method and the accuracy of distributed segmentation are affected by the degree of closeness between objects. 相似文献
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《Journal of The Franklin Institute》2021,358(14):6994-7012
Actuator faults often occur in physical systems, which seriously affect the transient performance and control accuracy of the system. For the finite-time consensus tracking problem of multiple Lagrangian systems with actuator faults and preset error constraints, a novel distributed fault-tolerant controller is proposed in this paper. The proposed controller is developed based on the barrier Lyapunov function method and the adding a power integrator technique, which can not only guarantee the steady-state performance of the system but also its transient performance. Due to its strong sensitivity to the variation of system errors, the proposed controller can quickly eliminate the system initial errors and the error perturbations caused by actuator faults. That is, the controller can guarantee that the consensus error converges to zero in a finite time and is always constrained within the preset error bound. Finally, the effectiveness of the developed controller is verified by simulation of a multi-manipulator system. 相似文献
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《Information processing & management》2023,60(3):103322
Using AI technology to automatically match Q&A pairs on online health platforms (OHP) can improve the efficiency of doctor-patient interaction. However, previous methods often neglected to fully exploit rich information contained in OHP, especially the medical expertise that could be leveraged through medical text modeling. Therefore, this paper proposes a model named MKGA-DM-NN, which first uses the named entities of the medical knowledge graph (KG) to identify the intention of the problem, and then uses graph embedding technology to learn the representation of entities and entity relationships in the KG. The proposed model also employs the relationship between entities in KG to optimize the hybrid attention mechanism. In addition, doctors' historical Q&A records on OHP are used to learn modeling doctors’ expertise to improve the accuracy of Q&A matching. This method is helpful to bridge the semantic gap of text and improve the accuracy and interpretability of medical Q&A matching. Through experiments on a real dataset from a Chinese well-known OHP, our model has been verified to be superior to the baseline models. The accuracy of our model is 4.4% higher than the best baseline model. The cost-sensitive error of our model is 13.53% lower than that of the best baseline model. The ablation experiment shows that the accuracy rate can be significantly improved by 8.72% by adding the doctor modeling module, and the cost-sensitive error can be significantly reduced by 17.27% by adding the medical KG module. 相似文献
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用正交设计方法求解非线性规划的区间约束最优化问题 总被引：1，自引：0，他引：1
给出了以正交设计原理为基础的两种方法———正交表法和加点正交表法,求解非线性规划的区间约束最优化问题。方法不要求目标函数可导,不依赖于初始点,计算速度快,算法简单,容易编成程序在计算机上执行。用检验考题对算法进行了验证,并进行了分析和探讨 相似文献
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[目的/意义]旨在将科技文献的价值进行量化,提高PageRank算法应用在科技文献排名中的准确性。[方法/过程]在加入时间因子的PageRank算法的改进算法WPageRank的基础上,加入引用相关度进行改进,并计算文献的固有价值,与文献的PageRank值进行加权求和,得到文献的最终价值。[结果/结论]本文提出的方法使新发表的高质量文献也可以获得较高排名,并且使领域内的高质量文献更容易被检索到,同时保证了检索的时效性和主题集中性。 相似文献
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2012年1月9日发射的我国首颗民用立体测图卫星“资源三号”是我国自主设计、研制和处理的精度最高的卫星。该卫星充分继承了我国资源卫星系列的平台技术,装载前后下视3台全色相机(下视相机分辨率2.1米,前后视相机分辨率3.5米)、1台多光谱相机(分辨率5.8米)、3台星敏感器和2台双频GPS接收机,实现对地三维摄影和多光谱探测,并获取相机成像时刻的高精度轨道与姿态测量数据。地面处理系统利用定期在轨几何检校成果,研究构建了“资源三号”测绘卫星高精度严密成像几何模型和有理函数模型。建立了满足测绘以及相关行业需求、与国内外成熟先进商业卫星接轨的“资源三号”影像产品体系。生产的“资源三号”影像产品无控制点平面精度达到10米,高程精度达到6米,带控制点平面精度达到3—4米,高程精度达到2—3米,处于国际同类领先水平,全面满足1∶5万和1∶2.5万比例尺的立体测图(平原、丘陵、山地和高山区)的精度要求,并可开拓研究其在1∶1万比例尺困难区测图应用的可行性。目前,“资源三号”测绘卫星在轨运行正常,卫星测绘应用成果丰硕,数据已开始全面应用于我国1∶5万基础地理信息产品生产以及更大比例尺地图的修测更新和地理国情监测,正积极服务于国土、规划、林业、农业、减灾等行业,并参与国际交流和合作。 相似文献