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91.
Tracking Performance Bound with Finite Control Energy and Erasure Channel Energy Constraint
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Baoxian Wang Ding‐Xue Zhang Zhi‐Hong Guan Bin Hu Yuehua Huang 《Asian journal of control》2016,18(3):1119-1129
This paper studies the tracking performance of the single‐input single‐output (SISO), finite dimensional, linear and time‐invariant (LTI) system under the channel input energy constraint over the Erasure channel. A new performance index is proposed which is minimized over all two‐degree‐of‐freedom stabilizing controllers. The explicit expressions of the lower bound of the performance index and the minimum of the signal‐to‐noise ratio are obtained. The results show that the performance bound is correlated to unstable poles, non‐minimum phase zeros and the packet loss probability. Finally, examples are given to validate the conclusions derived. 相似文献
92.
In this paper, an adaptive fuzzy PD+ controller is proposed for the attitude maneuver of rigid spacecraft. The novel controller adjusts the gains of the PD+ attitude controller online according to attitude errors and angular velocity errors during the maneuver procedure. Therefore, quick response and avoidance of actuator saturation can be achieved simultaneously. Furthermore, the adaptation mechanism is designed, based on Lyapunov theory, to guarantee the stability of the closed‐loop system. To achieve good performance of the closed‐loop system under the constraint of actuator saturation, controller parameter optimization is developed on the basis of a genetic algorithm. Simulation results show that the transient performance and robustness against parametric uncertainty and environmental disturbance of the adaptive fuzzy PD+ controller are better than those of a constant PD+ controller. 相似文献
93.
This paper deals with the development of effective techniques to automatically obtain the optimum management of petroleum fields aiming to increase the oil production during a given concession period of exploration. The optimization formulations of such a problem turn out to be highly multimodal, and may involve constraints. In this paper, we develop a robust particle swarm algorithm coupled with a novel adaptive constraint-handling technique to search for the global optimum of these formulations. However, this is a population-based method, which therefore requires a high number of evaluations of an objective function. Since the performance evaluation of a given management scheme requires a computationally expensive high-fidelity simulation, it is not practicable to use it directly to guide the search. In order to overcome this drawback, a Kriging surrogate model is used, which is trained offline via evaluations of a High-Fidelity simulator on a number of sample points. The optimizer then seeks the optimum of the surrogate model. 相似文献
94.
为了克服椭圆检测过程中对椭圆完整性和边缘梯度信息依赖性较强的缺点,提高椭圆目标的检测速度,提出了一种新的基于弧段提取的椭圆拟合方法;首先将梯度方向符号相同的相邻边缘点连接成弧段,然后根据弧段的凸性和象限分类定义新的弧选择策略,利用位置约束和弧对的椭圆中心估计提取候选椭圆,最后采用改进的拟合算法拟合椭圆;实验结果表明,基于弧段提取的椭圆拟合方法相对于LMEDS算法和RHT3具有更好的准确性、鲁棒性和稳定性,实时性也有一定的提高。 相似文献
95.
Segmentation of the left ventricle (LV) is a hot topic in cardiac magnetic resonance (MR) images analysis. In this paper, we present an automatic LV myocardial boundary segmentation method using the parametric active contour model (or snake model). By convolving the gradient map of an image, a fast external force named gradient vector convolution (GVC) is presented for the snake model. A circle-based energy is incorporated into the GVC snake model to extract the endocardium. With this prior constraint, the snake contour can conquer the unexpected local minimum stemming from artifacts and papillary muscle, etc. After the endocardium is detected, the original edge map around and within the endocardium is directly set to zero. This modified edge map is used to generate a new GVC force filed, which automatically pushes the snake contour directly to the epicardium by employing the endocardium result as initialization. Meanwhile, a novel shape-similarity based energy is proposed to prevent the snake contour from being strapped in faulty edges and to preserve weak boundaries. Both qualitative and quantitative evaluations on our dataset and the publicly available database (e.g. MICCAI 2009) demonstrate the good performance of our algorithm. 相似文献
96.
通过分析套箍和砌体横向应变关系,探讨了采用钢筋昆凝土套箍加固石拱桥对核心砌体的约束机理,并提出了套箍对核心砌体的约束应力及由于套箍约束作用使砌体强度提高的计算方法.同时,通过此方法对巴中市南江县龙渠大桥进行了加固设计,计算后得知主拱圈承载力得到明显提高,且实际运用效果良好. 相似文献
97.
基于偏微分方程及变分极值最小化的图像平滑方法可以有效地去除噪声,而且能够保护边缘信息,但由于噪声及纹理难以区分,使得纹理信息无法保留。提出一种纹理保护滤波算法,该算法利用图像分解模型将图像分解为几何结构分量及噪声/纹理分量,计算后者的局部方差,与传统变分能量最小化方法中的偏差惩罚项结合形成随纹理变化的约束,得到的模型在纹理区域滤波减少,从而保护了纹理信息。实验在视觉效果上得到了预期的结果,信噪比的计算对比也可以证明算法的有效性。 相似文献
98.
Pierre-Emmanuel Hladik Hadrien Cambazard Narendra Jussien 《Journal of Systems and Software》2008,81(1):132-149
In this paper, we present an original approach (CPRTA for “Constraint Programming for solving Real-Time Allocation”) based on constraint programming to solve a static allocation problem of hard real-time tasks. This problem consists in assigning periodic tasks to distributed processors in the context of fixed priority preemptive scheduling. CPRTA is built on dynamic constraint programming together with a learning method to find a feasible processor allocation under constraints. Two efficient new approaches are proposed and validated with experimental results. Moreover, CPRTA exhibits very interesting properties. It is complete (if a problem has no solution, the algorithm is able to prove it); it is non-parametric (it does not require specific tuning) thus allowing a large diversity of models to be easily considered. Finally, thanks to its capacity to explain failures, it offers attractive perspectives for guiding the architectural design process. 相似文献
99.
This paper proposes a methodology to compute quadratic performance bounds when the closed loop poles of a discrete-time multivariable control loop are confined to a disk, centred at the origin, and with radius less than one. The underlying philosophy in this constraint is to avoid certain undesirable dynamic features which arise in quadratic optimal designs. An expression for the performance loss due to the pole location constraint is also provided. Using numerical examples, we show that the performance loss is compensated by an improved transient performance, specially visible in the control signals. 相似文献
100.
Traditional clustering algorithms are inapplicable to many real-world problems where limited knowledge from domain experts
is available. Incorporating the domain knowledge can guide a clustering algorithm, consequently improving the quality of clustering.
In this paper, we propose SS-NMF: a semi-supervised non-negative matrix factorization framework for data clustering. In SS-NMF,
users are able to provide supervision for clustering in terms of pairwise constraints on a few data objects specifying whether
they “must” or “cannot” be clustered together. Through an iterative algorithm, we perform symmetric tri-factorization of the
data similarity matrix to infer the clusters. Theoretically, we show the correctness and convergence of SS-NMF. Moveover,
we show that SS-NMF provides a general framework for semi-supervised clustering. Existing approaches can be considered as
special cases of it. Through extensive experiments conducted on publicly available datasets, we demonstrate the superior performance
of SS-NMF for clustering.
相似文献
Ming DongEmail: |