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991.
In this paper we illustrate how nondeterminism can be used
conveniently and effectively in designing efficient deterministic
algorithms. In particular, our method gives a parameterized
algorithm of running time O((5.7 k)k n) for the 3-D matching
problem, which significantly improves the previous algorithm by
Downey et al. The algorithm can be generalized to
yield an improved algorithm for the r-D matching problem for any
positive integer r. The method can also be employed in designing
deterministic algorithms for other optimization problems as well. 相似文献
992.
Scale & Affine Invariant Interest Point Detectors 总被引:35,自引:0,他引:35
993.
Fast Hybrid Approach for Texturing Point Models 总被引:1,自引:0,他引:1
We present three methods for texturing point models from sample textures. The first method, the point parameterization method, uses a fast distortion‐bounded parameterization algorithm to flatten the point model's surface into one or more 2D patches. The sample texture is mapped onto these patches and alpha blending is used to minimize the discontinuity in the gaps between the patches. The second method is based on neighborhood matching where a color is assigned to each point by searching the best match within an irregular neighborhood. The hybrid method combines the former two methods, capitalizing on the advantages of both. The point parameterization method is used first to color most of the points, and the point neighborhood‐matching method is then applied to the points belonging to the gaps between the parameterized patches to minimize the discontinuity. We opt for fast texture generation, while some discontinuities may appear in the gaps of anisotropic textures. 相似文献
994.
Automating schema mapping is challenging. Previous approaches to automating schema mapping focus mainly on computing direct matches between two schemas. Schemas, however, rarely match directly. Thus, to complete the task of schema mapping, we must also compute indirect matches. In this paper, we present a composite approach for generating a source-to-target mapping that contains both direct and many indirect matches between a source schema and a target schema. Recognizing expected-data values associated with schema elements and applying schema-structure heuristics are the key ideas needed to compute indirect matches. Experiments we have conducted over several real-world application domains show encouraging results, yielding about 90% precision and recall measures for both direct and indirect matches. 相似文献
995.
Lia Toledo Moreira Mota Alexandre Assis Mota 《International Journal of Electrical Power & Energy Systems》2004,26(10):805-811
This paper is focused on electric power distribution substations load modeling using dynamic load parameters estimation. The load parameters are estimated using two models: the exponential and the ZIP load models. Since the load bus voltage and parameters are known one can determine the active and reactive power injections of this bus and include these pseudo-measurements in the state estimation in order to improve observability and estimation accuracy. The dynamic parameter estimation is developed using the weighted least squares method in a recursive form and the tests are carried out based on actual measurements. It is shown that the estimated parameters (for both load models) at a distribution substation are valid, since the obtained active and reactive power residuals are very close to zero. 相似文献
996.
基于负载观测的伺服系统抗扰研究 总被引:11,自引:5,他引:11
当负载变化时,按线性二次型状态反馈(LQSF)所设计的最优闭环控制系统是有静差的,为了减小和消除扰动静差,文中引入负载观测器实施对扰动负载的观测,并将其引入到电流调节器的输入端,作为速度调节器前馈补偿的控制输入,从而使系统具有优良的抗扰性能。文中给出了伺服系统负载观测的存在条件,负载观测器的构成方法,并在有或无负载观测结果参与控制的情况下,对实际系统做对比研究。系统的仿真和实验均证实了负载观测器参与系统控制的有效性。 相似文献
997.
GPS (Global Positioning System) has been widely used in car navigation systems. Most car navigation systems estimate the car position from GPS and DR (dead reckoning). However, the unknown GPS noise characteristic and the unbounded DR accumulation of errors over time make the position information with undesirable position errors. The map matching can improve the position accuracy and availability of the vehicular position system. In this paper, general principle of map matching is investigated according to segmentation and feature extraction, and a map matching algorithm based on D-S (Dempster-Shafer) evidence reasoning for GPS integrated navigation system is proposed, which can find the exact road on which a car moves. For the experiments, a car navigation system is developed with some sensors and the field test demonstrates the effectiveness and applicability of the algorithm for the car location and navigation. 相似文献
998.
999.
介绍了一种应用动态规划技术的图像匹配方法。该方法以区域相关为基础,通过在相关系数平面上寻找最佳路径来实现图像匹配。采用了规定视差搜寻范围,盒滤波技术和顺序一致性设定路径走向等办法优化匹配策略,加快匹配速度。用 VC 编写的算法对图像对进行匹配时,能实现快速准确的匹配。 相似文献
1000.
共轴法立体视觉三维测量的研究 总被引:4,自引:0,他引:4
提出一种新的立体视觉三维测量的双目布局方案——共轴法,推导了共轴情况下空间点和图像投影的对应关系及其外极线方程。与其他双目布局方案相比,具有匹配运算量少、共极性线方程简单等优点。 相似文献