共查询到20条相似文献，搜索用时 15 毫秒
1.
针对各向异性扩散方程抑制SAR图像相干斑时,需要进行多次迭代,很难用于实时处理的情况,提出一种改进算法.该算法根据图像变差系数,自适应调整中心像素与各方向扩散系数的权重,从而在均匀区域加速扩散过程,在非均匀区域保留原各向异性扩散方程的性能.利用机载SAR图像对算法性能进行验证,结果表明,算法仅需较少的迭代次数,就可以获得与常规各向异性扩散方程相干斑抑制相同的性能. 相似文献
2.
一种基于活动围道的纹理图像分割方法 总被引：1，自引：0，他引：1
本文将Gabor滤波器和各向异性扩散方程相结合，提出了一种基于活动围道的无监督纹理图像分割算法。采用基于总变分流的扩散函数，各向异性扩散方程可以有效地在保留纹理图像大尺度边界信息的同时对图像纹理区域进行平滑，获得比原始图像更易分割的简化图像。但是平滑过程中纹理信息的丧失，限制了该方法的通用性和有效性。为了在利用各向异性扩散方法的同时有效地提取和利用纹理信息，我们利用Gabor滤波器提取一组表征纹理方向性和尺度性的特征图像，同时将原始图像作为表征纹理灰度信息的一个特征通道考虑。再利用矢量形式的各向异性扩散方程对特征图像进行边界保持的各向异性平滑。我们将基于区域灰度统计参数估计的活动围道分割方法扩展到矢量空间，来对平滑后的纹理特征量进行分割。实验证明利用该纹理分割算法可以获得较好的效果。 相似文献
3.
Control of PDE-ODE cascades with Neumann interconnections 总被引：1，自引：0，他引：1
We extend several recent results on full-state feedback stabilization and state estimation of PDE-ODE cascades, where the PDEs are either of heat type or of wave type, from the previously considered cases where the interconnections are of Dirichlet type, to interconnections of Neumann type. The Neumann type interconnections constrain the PDE state to be subject to a Dirichlet boundary condition at the PDE-ODE interface, and employ the boundary value of the first spatial derivative of the PDE state to be the input to the ODE. In addition to considering heat-ODE and wave-ODE cascades, we also consider a cascade of a diffusion-convection PDE with an ODE, where the convection direction is “away” from the ODE. We refer to this case as a PDE-ODE cascade with “counter-convection.” This case is not only interesting because the PDE subsystem is unstable, but because the control signal is subject to competing effects of diffusion, which is in both directions in the one-dimensional domain, and counter-convection, which is in the direction that is opposite from the propagation direction of the standard delay (transport PDE) process. We rely on the diffusion process to propagate the control signal through the PDE towards the ODE, to stabilize the ODE. 相似文献
4.
提出一种基于变指数型扩散方程的向量值图像（例如RGB图像或多谱图像）恢复模型。在新的模型中,我们利用光滑后向量值图像的几何流形特征来判断图像的真假边缘,利用P（x）-Laplace型扩散系数来控制扩散量和扩散方向。由于扩散系数具有良好的自适应判断边缘能力,新的模型在图像恢复的同时良好地保持了图像边缘。通过数值实验,对比以往的全变差模型,所提模型具有更好的图像恢复效果,明显减少了＂块状＂效应。 相似文献
5.
本文提出了一种基于复数小波域上的多方向窗维纳滤波与偏微分方程保持边缘细节相结合的方法。针对小波域维纳滤波的方向性差,本方法先进行复数小波变换,获得六个方向上的图像信号,该六个方向进行方向维纳滤波,对图像进行去噪,以此引导偏微分方程中的扩散函数,实现各项异性进行扩散。实验结果表明,本文所提出的方法的峰值信噪比,以及视觉质量都较复小波去噪或各项异性非线性扩散去噪方法有明显的改善。 相似文献
6.
Starck等人的图像增强方法不能有效增强SAR图像中的边缘特征.为此,提出一种curvelet域SAR图像特征增强新方法.该方法充分利用curvelet变换多尺度多方向特性及其良好的各向异性特点,在curvelet域内提取图像的边缘特征,并定位特征curvelet系数.通过增强特征curvelet系数,达到增强图像边缘特征的目的.实验结果表明,与Starck等人的方法相比,本文算法能够更加有效性地增强SAR图像的边缘特征. 相似文献
7.
一种规整化的各向异性扩散相干斑抑制算法 总被引：2，自引：0，他引：2
针对基于各向异性扩散的相干斑抑制算法 (SRAD)中存在的不合理性 ,即算法在均匀区域内降噪特性一般 ,并且扩散系数的非凸可能导致解不收敛到正确的图像 ,从理论上进行了系统的分析和论证 ,并依据保持图像细节的规整化准则 ,构造出新的扩散控制系数 .在此基础上 ,进一步提出了一种更合理的规整化各向异性扩散模型 (RSRAD) ,该模型可以有效地克服SRAD中存在的不合理性 .实验结果表明 ,RSRAD算法优于SRAD . 相似文献
8.
Zhigang Ren Chao Xu Zhongcheng Zhou Zongze Wu Tehuan Chen 《Journal of The Franklin Institute》2019,356(1):173-195
In this paper, the boundary stabilization problem of a class of unstable reaction–advection–diffusion (RAD) systems described by a scalar parabolic partial differential equation (PDE) is considered. Different the previous research, we present a new gradient-based optimization framework for designing the optimal feedback kernel for stabilizing the unstable PDE system. Our new method does not require solving non-standard Riccati-type or Klein–Gorden-type PDEs. Instead, the feedback kernel is parameterized as a second-order polynomial whose coefficients are decision variables to be tuned via gradient-based dynamic optimization, where the gradients of the system cost functional (which penalizes both kernel and output magnitude) with respect to the decision parameters are computed by solving a so-called “costate” PDE in standard form. Special constraints are imposed on the kernel coefficients to ensure that the optimized kernel yields closed-loop stability. Finally, three numerical examples are illustrated to verify the effectiveness of the proposed approach. 相似文献
9.
A control system of an ODE and a diffusion PDE is discussed in this paper. The novelty lies in that the system is coupled. The method of PDE backstepping as well as some special skills is resorted in stabilizing the coupled PDE–ODE control system, which is transformed into an exponentially stable PDE–ODE cascade with an invertible integral transformation. And a state feedback boundary controller is designed. Moreover, an exponentially convergent observer for anti-collocated setup is proposed, and the output feedback boundary control problem is solved. For both the state and output feedback boundary controllers, exponential stability analyses in the sense of the corresponding norms for the resulting closed-loop systems are given through rigid proofs. 相似文献
10.
《Information processing & management》2022,59(3):102919
Similarity search with hashing has become one of the fundamental research topics in computer vision and multimedia. The current researches on semantic-preserving hashing mainly focus on exploring the semantic similarities between pointwise or pairwise samples in the visual space to generate discriminative hash codes. However, such learning schemes fail to explore the intrinsic latent features embedded in the high-dimensional feature space and they are difficult to capture the underlying topological structure of data, yielding low-quality hash codes for image retrieval. In this paper, we propose an ordinal-preserving latent graph hashing (OLGH) method, which derives the objective hash codes from the latent space and preserves the high-order locally topological structure of data into the learned hash codes. Specifically, we conceive a triplet constrained topology-preserving loss to uncover the ordinal-inferred local features in binary representation learning. By virtue of this, the learning system can implicitly capture the high-order similarities among samples during the feature learning process. Moreover, the well-designed latent subspace learning is built to acquire the noise-free latent features based on the sparse constrained supervised learning. As such, the latent under-explored characteristics of data are fully employed in subspace construction. Furthermore, the latent ordinal graph hashing is formulated by jointly exploiting latent space construction and ordinal graph learning. An efficient optimization algorithm is developed to solve the resulting problem to achieve the optimal solution. Extensive experiments conducted on diverse datasets show the effectiveness and superiority of the proposed method when compared to some advanced learning to hash algorithms for fast image retrieval. The source codes of this paper are available at https://github.com/DarrenZZhang/OLGH . 相似文献
11.
Jin-Jin Mei Ting-Zhu Huang Si Wang Xi-Le Zhao 《Journal of The Franklin Institute》2018,355(1):574-595
Image denoising is one of the most important issues in image processing. For removing the speckle noise in ultrasound images, researchers have proposed the minimization models based on the total variation (TV), which effectively preserve the sharp edges. But they simultaneously suffer form the undesired artifacts, such as the staircase effect. To overcome this shortcoming, we propose a convex model by combining with the total generalized variation (TGV) regularization for retaining the fine detail and reducing the staircase effect. Furthermore, we develop an alternating direction method of multiplier (ADMM) to solve the proposed model. Experimental results demonstrate that our model outperforms some state-of-the-art methods in terms of visual and quantitative measures. 相似文献
12.
Fatim Zahra Ait Bella Mohammed El Rhabi Abdelilah Hakim Amine Laghrib 《Journal of The Franklin Institute》2018,355(16):8225-8244
In this paper, we investigate two new reflectance and illumination decomposition models based on a nonlocal partial differential equation (PDE) applied to text images. Taking into consideration the higher regularity level of the illumination compared to the reflectance, we propose a nonlocal PDE which deals with repetitive structures and textures that characterize the text image much better compared to the classical local PDEs. The aim of this approach is to use the repetitive features of the reflectance to efficiently extract it from the non-uniform illumination. This idea is motivated by extending the range of application of the nonlocal operators to such a problem. Numerical experiments on both grayscale and color text images show the performance and strength of the proposed nonlocal PDE. 相似文献
13.
(Symmetric alpha-Stable)模型是小波域一种精确的图像模型 ，但是其计算复杂性高,本文在分析 模型的基础上，提出了高斯-柯西模型，将此模型作为图像的小波域先验模型信息，并用Bayesian估计器，算法复杂性上有显著的降低。另外，图像对数变换后的统计特性发生变化 ，需要在变换过程中加入均值调整的过程。实验结果表明，本文的算法模型在较好的保持了SAR图像结构的基础上，能较好的保留图像边缘信息和纹理特征，并能有效的抑制图像的斑点噪声，取得了良好的效果。 相似文献
14.
《Journal of The Franklin Institute》2021,358(16):8639-8655
Interconnection and damping assignment passivity-based control scheme has been used to stabilize many physical systems such as underactuated mechanical systems through total energy shaping. In this method, some partial differential equations (PDEs) related to kinetic and potential energy shaping shall be solved analytically. Finding a suitable desired inertia matrix as the solution of nonlinear PDEs relevant to kinetic energy shaping is a challenging problem. In this paper, a systematic approach to solving this matching equation for systems with one degree of underactuation is proposed. A special structure for desired inertia matrix is proposed to simplify the solution of the corresponding PDE. It is shown that the proposed method is more general than that of some reported methods in the literature. In order to derive a suitable desired inertia matrix, a necessary condition is also derived. The proposed method is applied to three examples, including pendubot, VTOL aircraft, and 2D SpiderCrane. 相似文献
15.
André Furtado 《Research Policy》1997,25(8):1243-1259
The central issue in this paper is to show the importance of public policies and sectoral patterns of technological change for institutional interaction in National Systems of Innovation (NSI), from the illustrative case study of French oil industry. This case is a relevant example of the French style of public policy, more well known as Colbertism. In the oil industry, Colbertism has demonstrated a greater ability to overcome some of its main challenges related to a weaker diffusion propensity and to a excessive concentration of R&D funds in some strategic sectors. The study of this industry demonstrates that sectoral patterns of technological change are very important to explain institutional interaction. Differences in the degree of appropriability between up and downstream of the oil industry had a great influence in this interaction and in public policies effectiveness. However, the technological diffusion success was not only due to some favorable technological factor but also to the nature of decision making, which was the outcome of a cooperative process. 相似文献
16.
[目的/意义]论文查重和查新功能是数字图书馆提供的信息服务之一,对学术界健康发展起到重要的作用。然而目前国内各高校图书馆的检测系统大多针对文字进行检测,而图像方面的检测鉴别存在很大的局限性,致使论文中对图像篡改的学术造假日益增多。因此,研究图像造假检测具有重大的意义。[方法/过程]针对这一问题,本文提出了一种能够鉴别论文中图像造假行为的模型,对图像数据检测平台框架进行设计。[结果/结论]通过实验证实了该模型的可行性与有效性,能够为数字图书馆图像篡改检测提供借鉴,提升信息服务质量,具有一定的理论价值。 相似文献
17.
在分析基于图像处理的人数统计方法基础上,提出基于图像边缘检测的人数统计新方法。分别采集室内彩色背景图像和目标图像,分别计算灰度图像的边缘检测结果,求出二者的差值图像后,连接边缘、填充为连通区域,计算目标图像中的人数。实验证明：该方法能满足室内人数比较多的人数统计要求,具有速度快和准确率较高的优点。 相似文献
18.
In this paper, a novel robust control strategy based on disturbance-compensation-gain (DCG) construction approach is proposed for small-scale unmanned helicopters in the presence of high-order mismatched disturbances. The overall control structure consists of two hierarchical layers. The inner-loop controller is to guarantee the stability of the unmanned helicopters subject to high-order mismatched disturbances. With the estimation of the disturbances and their successive derivatives via finite-time disturbance observer (FTDO), by properly designing some disturbance compensation gains, a novel robust controller is developed to remove the high-order mismatched disturbances from the output channels. The outer-loop controller is to produce flight commands for inner-loop system, as well as to track the reference trajectory, which is carried out with the dynamic inversion technique. The simulation results demonstrate that the unmanned helicopters are capable to perform flight missions autonomously with the proposed control strategy. 相似文献
19.
《Information processing & management》2023,60(1):103106
Teaching images, as an important auxiliary tool in teaching and learning, are fundamentally different from the general domain images. Besides visually similar images being more likely to share common labels, teaching images also face the challenge of visual-knowledge inconsistency, including intra-knowledge visual difference and inter-knowledge visual similarity. To address the above challenges, we present KBHN, a knowledge-aware bi-hypergraph network, which not only considers coarse-grained visual features, but also extracts fine-grained knowledge features that reflect knowledge intention hidden in teaching images. In detail, a visual hypergraph is constructed to connect images with visual similarity. It further enriches coarse-grained visual features by modeling the high-order visual relations among teaching images. Moreover, a knowledge hypergraph based on typical images is built to aggregate images with similar knowledge information, which innovatively extracts fine-grained knowledge features by modeling high-order knowledge correlations between local regions. Furthermore, a multi-head attention mechanism is adopted to fuse visual-knowledge features for enriching image representation. A teaching image dataset is constructed to train and validate our model, which contains 20744 real-world images annotated with 24 knowledge points. Experimental results demonstrate that KBHN, incorporating visual-knowledge features, achieves state-of-the-art performance compared to existing methods. 相似文献
20.
在进行篮球训练的过程中,通过运用不同的训练方法,能够不断提高训练的效果。表象训练就是其中的一种训练方法。因此,在本文的研究中,主要针对表象训练在篮球训练中的应用进行了具体的分析,希望通过本文的探讨,能够为相关方面的研究提供理论性的参考。 相似文献