短程硝化-反硝化脱氮及影响因素研究

短程硝化生物脱氮技术是近年来国内外水处理研究的一个热点。本文介绍短程硝化反应机理,分析影响亚硝酸累积的主要因素,重点探讨通过控制游离氨和pH达到亚硝酸根积累以实现短程硝化的途径。     

Color Image Segmentation for Objects of Interest with Modified Geodesic Active Contour Method

In this paper, we propose a novel variational method for color image segmentation using modified geodesic active contour method. Our goal is to detect Object(s) of Interest (OOI) from a given color image, regardless of other objects. The main novelty of our method is that we modify the stopping function in the functional of usual geodesic active contour method so that the new stopping function is coupled by a discrimination function of OOI. By minimizing the functional, the OOI is segmented. Firstly, we study the pixel properties of the OOI by sample pixels visually chosen from OOI. From these sample pixels, by the principal component analysis and interval estimation, the discrimination function of whether a pixel is in the OOI is obtained probabilistically. Then we propose the energy functional for the segmentation of OOI with new stopping function. Unlike usual stopping functions defined by the image gradient, our improved stopping function depends on not only the image gradient but also the discrimination function derived from the color information of OOI. As a result, better than usual active contour methods which detect all objects in the image, our modified active contour method can detect OOI but without unwanted objects. Experiments are conducted in both synthetic and natural images. The result shows that our algorithm is very efficient for detecting OOI even the background is complicated. Ling Pi received her PhD from the Department of Mathematics, East China Normal University in 2006. She is currently a lecturer in the Department of Mathematics, Shanghai Jiao Tong University. Her work involves the application of geometric and analytic methods to problems in image processing. Jinsong Fan received his MSc degree in mathematics from East China Normal University, Shanghai, China in 1996. Currently, he is a lecturer in the School of Mathematics and Information Science at Wenzhou University. His research interests include image processing and pattern recognition. Chaomin Shen received the MSc degree in Mathematics from the National University of Singapore (NUS) in 1998. He worked in the Centre for Remote Imaging, Sensing and Processing (CRISP), NUS as an associate scientist during 1998 to 2004. Currently he is a lecturer in Joint Laboratory for Imaging Science & Technology and Department of Computer Science, East China Normal University. His research interests include remote sensing applications and variational methods in image processing.     

基于总变分方法去噪的测地线活动轮廓的应用

传统的测地线活动轮廓（geodesic active contour）在目标轮廓的提取中虽然能使一条初始曲线朝着目标边界逼近,但是高斯平滑的各向同性性使得图像的边缘信息模糊甚至丢失,这样,曲线的演化过程会变得不稳定而导致演化速度变慢。据此,提出一种基于总变分方法的测地线活动轮廓模型。由于总变分方法可以在去除噪声的同时,对边缘的信息进行增强,实验证明该模型不但能够使曲线精准地收敛到期望轮廓上,且运算时间短。     

Kinetic theory of geodesic acoustic modes in toroidal plasmas: a brief review

Geodesic acoustic modes(GAM) are oscillating zonal structures unique to toroidal plasmas,and have been extensively studied in the past decades due to their potential capabilities of regulating microscopic turbulences and associated anomalous transport.This article reviews linear and nonlinear theories of GAM;with emphases on kinetic treatment,system nonuniformity and realistic magnetic geometry,in order to reflect the realistic experimental conditions.Specifically,in the linear physics,the resonant wave–particle interactions are discussed,with the application to resonant excitation by energetic particles(EPs).The theory of EP-induced GAM(EGAM) is applied to realistic devices for the interpretation of experimental observations,and global effects due to coupling to GAM continuum are also discussed.Meanwhile,in the nonlinear physics,the spontaneous GAM excitation by microscale turbulences is reviewed,including the effects of various system nonuniformities.A unified theoretical framework of GAM/EGAM is then constructed based on our present understandings.The first-principle-based GAM/EGAM theories reviewed here,thus,provide the tools needed for the understanding and interpretation of experimental/numerical results.     

金相图像的晶界恢复与重建

针对定量金相分析中金相图像的晶界恢复与重建以及数学形态学在图像处理中的特殊作用,从理论上证明了传统膨胀运算对图像灰度连续性的影响及影响程度与结构元素尺寸的关系,并对传统的膨胀运算的定义做了改进,据此提出了多尺度测地膨胀算法并以此恢复和重建金相图像的晶界.首先依据改进的膨胀运算对金相图像进行预处理;然后用多尺度迭代腐蚀和...     

A Note on the Kepler Problem

J. Moser proved that the flow arising in the Kepler problem and restricted to the manifold of the constant energy E < 0 is equivalent to the geodesic flow on a sphere. This was proved by means of some algebraic manipulations with the Hamilton function. In a similar way Yu. S. Osipov proved that this flow is equivalent to the geodesic flow on the Euclidean space for E = 0 and on the Lobachevskii space for E < 0. In this paper results of such kind are related to the approach to the Kepler problem suggested by Hamilton (this approach seems to be the simplest one). For the planar Kepler problem one first considers the picture arising on the hodograph plane, where the hodograph curves turn out to be circles or arcs of circles. For fixed E one obtains a net (2-parameter linear system) of circles which in the case of E < 0 can be obtained from the system of great circles on a sphere by a stereographic projection; related geometric construction exists also for other E. This leads in a geometrical way to Moser's result. Moser showed also that for E < 0 the trajectory space of the covering flow on the universal covering space (which is a three-dimensional sphere ³) is a two-dimensional sphere ²; the corresponding map ^{3 2} is the Hopf fibration. An additional remark made below is that under appropriate normalizations and modifications this is the map

紧致极小子流形的积分不等式及其性质

利用数量曲率 ,建立了紧致极小子流形的内蕴积分不等式 ,并依此对第二基本形式长度的平方满足某些条件的紧致极小子流形 ,刻划了它们的性质     

基于短程线主动轮廓线的图像多目标面积同时测量研究

提出了一种新颖的图像多目标面积的同时测量方法,它可以同时精确测量多个不同形状的图像目标面积。该方法应用了短程线主动轮廓线模型,它分为2个步骤。它首先利用水平集函数的迭代使主动轮廓线由初始位置向各个目标的轮廓边缘收敛。其次,对于收敛后的主动轮廓线,使用亚像素面积测量和计数图像目标内部像素个数,从而同时求出各个图像目标面积。实验表明该方法的测量重复性误差小于0.5% 。和传统的面积测量方法比较,这种方法具有测量效率高（同时测量多目标面积）和测量精度高的优点。     

张拉膜结构模型全过程试验研究

本文对一较大的足尺张拉膜结构模型进行了张拉成型和荷载试验,并进行了模型的自振频率测量试验。通过对该模型张拉成型阶段索、膜内应力值的测量表明,张拉膜结构在预应力阶段基本符合等应力假设,但在拉索附近由于边缘效应,膜内应力并不均匀。模型的荷载试验表明,在正常使用荷载作用下结构基本处于弹性工作状态。模型的自振频率测量试验证明,张拉膜结构振动存在与空气耦合引起的附加质量影响,其阻尼比值及变化规律与一般刚性结构存在明显差异。