Robust Corner Detection Based on Multi-scale Curvature Product in B-spline Scale Space

这份报纸在 B 花键弯曲规模空间的框架论述一种多尺度的弯曲产品角落察觉技术。规模产品功能在不同规模从轮廓的弯曲产品被导出。角落被 thresholding 作为本地最大值构造越过几规模的弯曲产品结果。通过规模产品，本地化精确性和察觉表演能显著地以 CNN 标准被改进。实验也证明那个建议方法显示出坚韧性到高频率细节并且提供有希望的察觉结果。

The algorithm of 3D multi-scale volumetric curvature and its application

To fully extract and mine the multi-scale features of reservoirs and geologic structures in time/depth and space dimensions, a new 3D multi-scale volumetric curvature （MSVC） methodology is presented in this paper. We also propose a fast algorithm for computing 3D volumetric curvature. In comparison to conventional volumetric curvature attributes, its main improvements and key algorithms introduce multi-frequency components expansion in time-frequency domain and the corresponding multi-scale adaptive differential operator in the wavenumber domain, into the volumetric curvature calculation. This methodology can simultaneously depict seismic multi-scale features in both time and space. Additionally, we use data fusion of volumetric curvatures at various scales to take full advantage of the geologic features and anomalies extracted by curvature measurements at different scales. The 3D MSVC can highlight geologic anomalies and reduce noise at the same time. Thus, it improves the interpretation efficiency of curvature attributes analysis. The 3D MSVC is applied to both land and marine 3D seismic data. The results demonstrate that it can indicate the spatial distribution of reservoirs, detect faults and fracture zones, and identify their multi-scale properties.

Application of structural curvature of coalbed floor on CBM development in the Zaoyuan block of the southern Qinshui Basin

Based on controls of structural style and the position in coalbed methane (CBM) development, we used a method of curvatures to study its relations with CBM development parameters. We calculated structural curvatures of contours of the No.3 coal seam floor of the Shanxi Formation in the Zaoyuan block of the Qinshui Basin and analyzed its relations with development parameters of coalbed methane wells. The results show that structural curvature is negatively related to coal reservoir pressure, while positively related to permeability. With an increase in structural curvature, the average production of coalbed methane wells increases at first and then decreases, reaching the highest production at 0.02 m–1 of structural curvature. Therefore, structural cur-vature can be an important index for potential evaluation of coalbed methane development and provide a basis for siting coalbed methane wells.

Designing Bézier surfaces minimizing the L^2-norm of the Gaussian curvature

In freeform surface modelling, developable surfaces have much application value. But, in 3D space, there is not always a regular developable surface which interpolates the given boundary of an arbitrary piecewise smooth closed curve. In this paper, tensor product Bézier surfaces interpolating the closed curves are determined and the resulting surface is a minimum of the functional defined by the L2-integral norm of the Gaussian curvature. The Gaussian curvature of the surfaces is minimized by the method of solving nonlinear optimization problems. An improved approach trust-region form method is proposed. A simple application example is also given.

A convergent flow in warped product spaces

In this paper,we study a kind of curvature flow in warped product spaces.We obtain convergence results under barrier conditions and restrictions on prescribed function.We also obtain the asymptotic behavior of a kind of inverse curvature flow in Schwarzschild manifold.

ON DOUBLY WARPED PRODUCT OF COMPLEX FINSLER MANIFOLDS

Let （M1, F1） and （M2, F2） be two strongly pseudoconvex complex Finsler man- ifolds. The doubly wraped product complex Finsler manifold （f2 M1 x h M2, F） of （M1, F1） and （M2, F2） is the product manifold M1 x M2 endowed with the warped product complex 2 2 Finsler metric F2 = f2F1 ＋ fl F2, where fl and f2 are positive smooth functions on M1 and M2, respectively. In this paper, the most often used complex Finsler connections, holomorphic curvature, Ricci scalar curvature, and real geodesics of the DWP-complex Finsler manifold are derived in terms of the corresponding objects of its components. Necessary and sufficient conditions for the DWP-complex Finsler manifold to be K/ihler Finsler （resp., weakly K/ihler Finsler, complex Berwald, weakly complex Berwald, complex Landsberg） manifold are ob- tained, respectively. It is proved that if （M1, F1） and （M2,F2） are projectively flat, then the DWP-complex Finsler manifold is projectively flat if and only if fl and f2 are positive constants.

SOME RESULTS ON PRODUCT COMPLEX FINSLER MANIFOLDS

Let （M, F ） be the product complex Finsler manifold of two strongly pseudoconvex complex Finsler manifolds （M 1 , F 1 ） and （M 2 , F 2 ）. In this paper, we obtain the relationship between the Chern Finsler connection coefficients Γ i ; k associated to F and the Chern Finsler connection coefficients Γ a ; c , Γα ; γ associated to F 1 , F 2 , respectively. As applications we prove that, if both （M 1 , F 1 ） and （M 2 , F 2 ） are strongly Ka¨hler Finsler （complex Berwald, or locally complex Minkowski, respectively） manifolds, so does （M, F ）. Furthermore, we prove that the holomorphic curvature K F = 0 if and only if K F1 = 0 and K F2 = 0.

Osserman Conditions in Lightlike Warped Product Geometry

In this paper, we consider Osserman conditions on lightlike warped product (sub-)manifolds with respect to the Jacobi Operator. We define the Jacobi operator for lightlike warped product manifold and introduce a study of lightlike warped product Osserman manifolds. For the coisotropic case with totally degenerates first factor, we prove that this class consists of Einstein and locally Osserman lightlike warped product.

PRODUCT IMAGE RETRIEVAL BASED ON CO-FEATURES OF THE OBJECT

In this paper, we propose a product image retrieval method based on the object contour corners, image texture and color. The product image mainly highlights the object and its background is very simple. According to these characteristics, we represent the object using its contour, and detect the corners of contour to reduce the number of pixels. Every corner is described using its approximate curvature based on distance. In addition, the Block Difference of Inverse Probabilities (BDIP) and Block Variation of Local Correlation (BVLC) texture features and color moment are extracted from image's HIS color space. Finally, dynamic time warping method is used to match features with different length. In order to demonstrate the effect of the proposed method, we carry out experiments in Mi-crosoft product image database, and compare it with other feature descriptors. The retrieval precision and recall curves show that our method is feasible.

两阶段注采管损伤仿真识别方法研究

注采管的微裂缝或微损伤会逐渐发展为疲劳断裂破坏,给储气库的安全运营带来巨大挑战。于是,以注采管为对象,将改进灰关联度与柔度曲率差相结合形成新的损伤识别指标,提取出流固耦合作用下注采管有限元模型的固有频率和振型,以计算改进灰关联柔度曲率差指标(IGMFC)值,对结构损伤进行定位,并利用改进后的粒子群算法(IPSO)优化极限学习机(ELM)对结构进行损伤定量。结果表明指标IGMFC具有很好的准确度、灵敏度和抗噪性,且优化后的极限学习机量化损伤程度的误差在2%以内,损伤识别结果误差仅为2.92%,有一定的应用价值。

四向加权香农熵最大化导向的自动阈值分割方法

灰度图像的灰度直方图可以呈现出无峰、单峰、双峰或多峰的形态特征,但传统熵阈值分割方法大多仅适合处理具有单峰或双峰形态特征的灰度图像。为了提高熵阈值分割方法的分割精度和分割适应性,提出一种四向加权香农熵最大化导向的自动阈值分割方法 FWSE(Four-directional Weighted Shannon Entropy)。首先用新设计的方向性Prewitt卷积核在4个方向进行多尺度乘积变换(MPT),以获得一系列方向性MPT图像;再基于三次样条插值函数和曲率最大化准则自动计算出每个方向的最优MPT图像;其次在每个方向上通过内外轮廓图像对最优MPT图像的像素进行重新取样,以获取重构的灰度直方图,并在此基础上计算相应的香农熵;最后以4个方向的加权香农熵最大化为准则选取最佳分割阈值。与新近的3种阈值分割方法以及2种非阈值分割方法在4幅合成图像和100幅真实世界图像上进行实验,结果显示:在合成图像上,FWSE方法的平均马修斯相关系数(MCC)达到了0.999;在真实世界图像上,FWSE方法与其他5个分割方法的平均MCC分别是0.974、0.927、0.668、0.595、0.550和0.525。这表明FWSE方法具有更高的分割精度和更灵活的分割适应性。

Finsler warped product metrics with special Riemannian curvature properties

One of the fundamental problems in Finsler geometry is to study Finsler metrics of constant(or scalar)curvature.In this paper,we refine and improve Chen-Shen-Zhao equations characterizing Finsler warped product metrics of scalar flag curvature.In particular,we find equations that characterize Finsler warped product metrics of constant flag curvature.Then we improve the Chen-Shen-Zhao result on characterizing Einstein Finsler warped product metrics.As its application we construct explicitly many new warped product Douglas metrics of constant Ricci curvature by using known locally projectively flat spherically symmetric metrics of constant flag curvature.

Existence and Uniqueness for the Non-Compact Yamabe Problem of Negative Curvature Type

We study existence and uniqueness results for the Yamabe problem on non-compact manifolds of negative curvature type.Ourfirst existence and uniqueness result concerns those such manifolds which are asymptotically locally hyperbolic.In this context,our result requires only a partial C2 decay of the metric,namely the full decay of the metric in C1 and the decay of the scalar curvature.In particular,no decay of the Ricci curvature is assumed.In our second result we establish that a local volume ratio condition,when combined with negativity of the scalar curvature at infinity,is sufficient for existence of a solution.Our volume ratio condition appears tight.This paper is based on the DPhil thesis of thefirst author.

S-curvature of Doubly Warped Product of Finsler Manifolds

Doubly warped product of Finsler manifolds is useful in theoretical physics,particularly in general relativity.In this paper,we study doubly warped product of Finsler manifolds with isotropic mean Berwald curvature or weak isotropic S-curvature.

Spacelike Graphs with Parallel Mean Curvature in Pseudo-Riemannian Product Manifolds

Abstract The author introduces the w-function defined on the considered spacelike graph M. Under the growth conditions w = o（log z） and w = o（r）, two Bernstein type theorems for M in Rm^n＋m are got, where z and r are the pseudo-Euclidean distance and the distance function on M to some fixed point respectively. As the ambient space is a curved pseudo- Riemannian product of two Riemannian manifolds （∑1,g1） and （∑2,g2） of dimensions n and m, a Bernstein type result for n =2 under some curvature conditions on E1 and E2 and the growth condition w = o（r） is also got. As more general cases, under some curvature conditions on the ambient space and the growth condition w = o（r） or w = o（√r）, the author concludes that if M has parallel mean curvature, then M is maximal.

分砂层地质曲率分析在裂缝预测中的应用

曲率分析是裂缝分布预测中的传统方法,并在长期的应用过程中被逐步改进。研究中使用的地质曲率就是一种新的地质层面曲率算法,该方法兼具数学上的严密性和地质上的实际意义。文中研究的地质对象是侏罗系某组的3个横向分布稳定的砂层。该地区以前的研究是运用整个组的顶面构造图来研究裂缝的分布规律,对构造与裂缝分布之间的内在关系仅停留在简单的和定性的认识上。为了搞清构造对裂缝分布的控制作用,作者通过三维地震精细解释各砂层顶面的构造图,用改进的地质曲率算法计算各砂层的顶面地质曲率,并运用地质曲率值作为裂缝预测参数。研究结果表明,各砂层的地质曲率分布规律和数值高低之间均存在显著差异,各层之间的曲率数值总体差异与各层之间的产能总体差异具有很好的匹配关系,各砂层在各井点处的自然产能高低与曲率值高低具有较好的统计相关关系。同时,曲率分析证实了研究区内构造复合关系的存在。研究发现,构造的叠合部位往往是裂缝的发育区。这些结论的得出对裂缝的钻前预测是十分有意义的。

地震方法识别乌夏断裂带风城组白云质灰岩裂缝

针对准噶尔盆地西北缘白云质灰岩裂缝型储集层,采用了小波尺度积边缘检测、广义希尔伯特变换、曲率分析等裂缝检测方法。经模型试验,以上方法具有较高的横向分辨能力和抗噪能力。3种方法在乌夏断裂带风城组1段进行了应用,通过与区域构造特征及井资料的相关分析,可看出这些方法在研究区应用效果良好。3种方法配套使用,可相互映证和补充,提高检测结果的可靠性。

深部煤储层应力敏感性特征及其对煤层气产能的影响

深部煤储层处于高地应力环境中,其渗透率变化特征与浅部存在较大差异,为研究有效应力对深部煤储层渗透率的差异性影响,以及应力敏感性各向异性特征,以沁水盆地横岭区块15号煤层为研究对象,采样深度1200~1700 m,采用覆压孔渗实验,开展平行层理和垂直层理样品在不同有效应力下的渗透率变化规律研究,探究其应力敏感性特征及其对煤层气产能的影响。结果表明:渗透率随有效应力的增加呈幂指函数降低,平行层理面渗透率总体高于垂直层理面,且在2个方向上渗透率变化规律呈正相关性。选取储层孔裂隙压缩系数、渗透率损害率和渗透率曲率3个参数作为煤储层应力敏感性评价指标,其中,孔裂隙压缩系数随有效应力增加,以5 MPa为界限先后呈现正相关性和负相关性,渗透率损害率和渗透率曲率分别与有效应力呈指数上升和下降的规律。基于应力敏感性参数,推导出煤层气井产能模型,模型显示,不考虑应力敏感性的气井产量高于考虑应力敏感性,揭示了应力敏感性对煤层气产量的影响程度,即在5 MPa生产压差下,气井的产量降低幅度随应力敏感性系数的增大整体呈增高趋势。针对应力敏感性的阶段划分,研究区目标煤层在煤层气排采过程中应采用小–中–大的排采方案来控制生产流量。

基于多尺度曲率乘积的鲁棒图像角点检测

为了更好地进行图像角点检测,在曲率尺度空间(CSS)框架下,提出了一种基于多尺度乘积的角点检测技术,其中曲率尺度积函数被定义为各个尺度下轮廓曲率的乘积,而角点则被定义为曲率乘积的局部极值点。这种尺度积不仅能显著地增强角点曲率极值点的峰值,同时能抑制噪声影响,而且不改变角点的位置,为了说明该技术的优点,根据角点数一致性(CCN)准则证明了该技术优于其他的角点检测算法。实验结果表明,该方法不仅具备优越的检测效果,并对噪声有较强的鲁棒性。

拟常曲率黎曼流形中子流形的几何不等式的一些注记（英文）

本文研究了拟常曲率黎曼流形中子流形的Chen不等式.利用代数技巧,建立了Chen广义不等式、Chen-Ricci不等式和关于卷积函数和平均曲率平方的不等式,推广了zgr和Chen的一些结果.