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121.
视觉测量具有结构简单、成本低、非接触式测量的优点,利用视觉位姿测量结果对空间展开机构进行定位具有良好的应用前景.实际应用中需要将视觉测量数据转换到物空间坐标系从而对定位系统的控制量提供指导.针对相机外参数标定操作繁琐、需要额外设备、不利于在轨实现等缺点,提出了一种利用运动样本空间构建坐标系转换关系的数据处理方法,根据取样空间内构建的补偿方程,可以将各自由度的视觉测量数据转换到控制器坐标系上,同时能够校正由于安装、配准等导致的系统误差,从而实现高精度的空间 目标定位.实验结果表明,在1.7 m的测量距离下,所搭建单相机测量系统的位置与转角测量精度可达0.02 mm和0.003°,验证了所研究方法的有效性和实用性. 相似文献
122.
Kang Zhou Qicheng Sun Lanlei Guo Qingjun Du Yueliang Liu 《Journal of Dispersion Science and Technology》2013,34(10):1523-1530
After being injected into the porous media, the dispersion system of preformed particle gel (PPG) tends to enter high permeability regions and block water channeling passages, which forces the subsequent water to turn to the low permeability regions and thus increases sweep efficiency and enhances oil recovery. However, it is still unclear about the influence factors and the mechanisms how PPG increases water flow resistance, which limits the application of PPG in more oilfields. Therefore, the paper combines the lattice Boltzmann method (LBM), the discrete element method (DEM) and the improved immersed moving boundary (IMB) method to simulate the migration of deformable PPG in porous media. On the basis, the paper quantitatively analyzes the variation law of displacement pressure across the porous media and discusses the influence factors such as the PPG diameter, elasticity modulus and the number concentration. Results indicate that, because of the friction and retention of PPG in pore-throat, the displacement pressure across the porous media during PPG flooding is much higher than that during water flooding. In other words, the existence of PPG increases the flow resistance of injected water. Besides, the displacement pressure is always fluctuant resulting from the continuous process of PPG migration, retention, deformation and remigration. Influence factor analysis shows that the incremental value and fluctuation degree of flow resistance increase with the PPG diameter, elasticity modulus and the number concentration. The study not only provides useful reference for future PPG flooding, but also benefits the development of deformable particle flow theory. 相似文献
123.
In this paper, a class of the direct methods for discretization of fractional order transfer functions is studied in the sense of stability preservation. The stability boundary curve is exactly determined for these discretization methods. Having this boundary helps us to recognize whether the original system and its discretized model are the same in the sense of stability. Finally, some illustrative examples are presented to evaluate achievements of the paper. 相似文献
124.
In this work, the up-down counter detector for the acquisition of GPS signals is modified to use dual-thresholds for each trial. Closed form expressions for the mean and variance of the dwell time and the probabilities of detection and false alarm are derived. The new detector has a significantly smaller mean dwell time than the conventional single-threshold up-down counter and a lower dwell time variance when signals are weak. Further, the new detector has a low computational load, when compared to the optimal sequential probability ratio test (SPRT), whose main disadvantage is its computational complexity. 相似文献
125.
《Journal of Coordination Chemistry》2012,65(12):2172-2180
A series of Co(II), Ni(II), Cu(II), and Zn(II) complexes of bi- and tridentate hydrazones were prepared. Ligands L1 and L2 were synthesized by the condensation of 2-mercapto-3-hydrazinoquinoxaline with 2-hydroxy-3-formylquinoline and 3-acetylcoumarin, respectively. The compounds were characterized by various spectro-analytical techniques and magnetic moment studies. The complexes are found to be monomeric and non-electrolytes. In these complexes, [CuL1Cl2] has square pyramidal geometry and others have octahedral. The copper complexes are electrochemically active in the applied potential range. 相似文献
126.
We report the results of our investigation of magnetization and heat capacity on a series of compounds CeYxNiGe2 () under the influence of external magnetic field. Our studies of the thermodynamic quantity on these compounds indicate that magnetic frustration persists in Ce0.9Y0.1NiGe2, as also reported for the parent compound CeNiGe2. The weak signature of this frustration is also noted in Ce0.8Y0.2NiGe2, whereas, it is suppressed in Ce0.6Y0.4NiGe2. Heat capacity studies on Ce0.9Y0.1NiGe2 and Ce0.8Y0.2NiGe2 indicate the presence of a new magnetic anomaly at high field which indicates that quantum criticality is absent in these compounds. However, for Ce0.6Y0.4NiGe2 such an anomaly is not noted. For this later compound, the magnetic field (H) and temperature (T) dependence of heat capacity and magnetization obey scaling above critical fields. However, the obtained scaling critical parameter (δ) is 1.6, which is away from mean field value of 3. This deviation suggests the presence of unusual fluctuations and anomalous quantum criticality in these compounds. This unusual fluctuation may arise from disorderness induced by Y-substitution. 相似文献
127.
连铸机所配备的专用精确诱导无线位置检测系统必须具备高精度和高可靠性。文章通过对某钢厂实际工程应用,证明诱导无线定位在横移台车上使用,定位准确,误差满足设计要求,不大于10mm。 相似文献
128.
经过半个世纪的发展,半导体技术不仅在制造功能强大的IC及各式各样的半导体分立器件方面,对社会发展起到不可估量的推动作用,而且对其他技术领域也产生了深刻的影响。在当前世界经济衰退浪潮的冲击下,无源电子元件领域借鉴、融合半导体技术以提高自身创新能力,加快产品升级是抵御冲击的值得关注的措施之一。 相似文献
129.
This paper deals with ultrasound medical image processing, particularly to filter the noise while preserving the edges and
structures of information. The mathematical processing consists in solving by a numerical way a nonlinear evolutive boundary
value problem. Several numerical semi-implicit time marching schemes are considered and analyzed. At each time step, parallel
synchronous or asynchronous Schwarz alternating methods are used to solve the linear system and its convergence is studied.
Lastly, the results of sequential and parallel simulations are presented.
相似文献
130.
Satellite and terrestrial components of IMT?Advanced need to be integrated so that the traditional strengths of each compo?nent can be fully exploited. LTE/LTE?A is now a recognized foundation of terre... 相似文献