Prediction of Long-Term Extreme Response of Fish Cage Using Environmental Contour Method

The fish cage design requires accurate predictions of long-term extreme loads and responses.Compared with the time-consuming full long-term analysis method integrating all the probability distribution of the short-term extremes,the environmental contour method gains much attention in predicting the long-term extreme values due to the less computational effort.This paper investigates the long-term extreme response of a fish cage using the environmental contour method.The fish cage is numerically simulated based on the lumped-mass method and the curved beam theory.Based on the one-dimensional(1D)and two-dimensional(2D)environmental contour,the extreme responses,including the surge and heave motions,mooring force,and vertical bending of the floater,are predicted for different return periods and compared with the full long-term analysis results.Results indicate that the 1D method greatly underestimates the extreme values.The 2D environmental contour method with a higher percentile level,namely90%,provides reasonable estimations and seems to be suitable for the long-term value analysis.Sensitivity studies show that the mooring arrangement and the bending stiffness have great effects on the bending moment and the mooring force and the mooring line pre-tension has minor effects on the fish cage response.

Using Finite Element and Contour Method to Evaluate Residual Stress in Thick Ti-6Al-4V Alloy Welded by Electron Beam Welding

This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates（50 mm thick） by using finite element and contour measurement methods.A three-dimensional finite element model of 50-mmthick titanium component was proposed,in which a column–cone combined heat source model was used to simulate the temperature field and a thermo-elastic–plastic model to analyze residual stress in a weld joint based on ABAQUS software.Considering the uncertainty of welding simulation,the computation was calibrated by experimental data of contour measurement method.Both test and simulated results show that residual stresses on the surface and inside the weld zone are significantly different and present a narrow and large gradient feature in the weld joint.The peak tensile stress exceeds the yield strength of base materials inside weld,which are distinctly different from residual stress of the thin Ti-6Al-4V alloy plates presented in references before.

A B-spline active contour model based on finite element method

A B-spline active contour model based on finite element method is presented, into which the advantages of a B-spline active contour attributing to its fewer parameters and its smoothness is built accompanied with reduced computational complexity and better numerical stability resulted from the finite element method. In this model, a cubic B-spline segment is taken as an element, and the finite element method is adopted to solve the energy minimization problem of the B-spline active contour, thus to implement image segmentation. Experiment results verify that this method is efficient for B-spline active contour, which attains stable, accurate and faster convergence.

Gradient-based optimization method for producing a contoured beam with single-fed reflector antenna

A gradient-based optimization method for producing a contoured beam by using a single-fed reflector antenna is presented. First, a quick and accurate pattern approximation formula based on physical optics(PO) is adopted to calculate the gradients of the directivity with respect to reflector's nodal displacements. Because the approximation formula is a linear function of nodal displacements, the gradient can be easily derived. Then, the method of the steepest descent is adopted, and an optimization iteration procedure is proposed. The iteration procedure includes two loops: an inner loop and an outer loop. In the inner loop, the gradient and pattern are calculated by matrix operation, which is very fast by using the pre-calculated data in the outer loop. In the outer loop, the ideal terms used in the inner loop to calculate the gradient and pattern are updated, and the real pattern is calculated by the PO method. Due to the high approximation accuracy, when the outer loop is performed once, the inner loop can be performed many times, which will save much time because the integration is replaced by matrix operation. In the end, a contoured beam covering the continental United States(CONUS) is designed, and simulation results show the effectiveness of the proposed algorithm.

基于机器视觉的低对比度工件轮廓尺寸标定方法

受照明不均匀和图像噪声的影响,低对比度工件的轮廓可能不连续且边缘模糊,导致尺寸参数标定结果误差增加,影响了工件尺寸参数的准确性。针对这个问题,引入机器视觉技术来改善工件轮廓的清晰度和准确性。首先,通过摄像机和相关设备的布置,获取工件的图像,针对低对比度可能存在的噪声,采用正交处理方法对图像进行降噪以提高图像质量;接下来,基于预处理图像提取工件表面形态与轮廓信息,为尺寸参数标定提供参考和基准。为了进行标定,采用一维标靶的设计,建立相机平面到一维标靶平面的空间映射路径。在这个映射路径下将工件轮廓映射到二维平面坐标上,实现尺寸标定。对比实验结果表明:设计的方法应用效果良好,可以标定低对比度工件轮廓尺寸,标定后的工件轮廓尺寸与设计值的误差小于1 mm,提高工件的加工、生产制造精度。

Estimating Design Loads with Environmental Contour Approach Using Copulas for an Offshore Jacket Platform

Jacket-type offshore platforms are widely used for oil, gas field, and energy development in shallow water. The design of a jacket structure is highly dependent on target environmental variables. This study focuses on a strategy to estimate design loads for offshore jacket structures based on an environmental contour approach. In addition to the popular conditional distribution model, various classes of bivariate copulas are adopted to construct joint distributions of environmental variables. Analytical formulations of environmental contours based on various models are presented and discussed in this study. The design loads are examined by dynamic response analysis of jacket platform. Results suggest that the conditional model is not recommended for use in estimating design loads in sampling locations due to poor fitting results. Independent copula produces conservative design loads and the extreme response obtained using the conditional model are smaller than those determined by copulas. The suitability of a model for contour construction varies with the origin of wave data. This study provides a reference for the design load estimation of jacket structures and offers an alternative procedure to determine the design criteria for offshore structures.

基于改进萤火虫算法的永磁同步电机多模态优化设计

永磁同步电机的结构参数选择往往是多模态、非线性的优化问题,同时其结构优化设计又存在计算分析时间过长、计算效率过低、收敛慢等问题。文中针对此类问题提出了一种基于改进萤火虫算法的新型多模态优化算法。改进萤火虫算法主要引用了等值线概念并通过克里金(Kriging)代理模型自适应确定子计算区域,从而获得多个全局最优解和局部解,并且引入单纯形法和改进停止条件以提高算法效率。此外,研究了分层余一法用于检验代理模型精度。最后,将其应用到永磁同步电机的结构优化中,使齿槽转矩成功降低了38.33%。

微针疗法的理论渊源与辨证体系

微针疗法又称微针系统疗法,是一门新兴的诊疗一体操作技术,在近几十年得到了飞速发展,是近现代针灸学中至关重要的一部分。由于不同微针疗法之间的操作部位及方法理论之间存在较大差异,为探究其间存在的规律与共性,利用公开发表的文献内容,对微针疗法的起源发展、理论基础、辨证方式三个方面进行了梳理归纳,并列举了七种微针疗法。大体总结出三种辨证体系,包括以第二掌骨侧针法、全息律针法、耳针疗法和方氏头针疗法为代表的穴位全息辨证体系;以眼针疗法、腹针疗法为代表的八廓分区辨证体系以及由经典理论指导的其他辨证理论体系包括根据五色辨证理论演变而来的面针疗法和根据皮部理论发展而来的腕踝针疗法。希望对微针疗法的临床应用及发展提供一定的启示和帮助。

基于ZYNQ的线激光轮廓传感器设计

为了直接获取工件轮廓点云,设计一种基于ZYNQ可编程芯片的线激光轮廓传感器。以ZYNQ芯片为核心处理器,设计传感器的图像采集与处理硬件电路。根据相机畸变模型,通过双线性插值法矫正各像素点的灰度值,研究基于法向迭代的灰度重心法以提取激光条纹中心线,结合相机参数和激光光平面方程的标定,计算相机坐标系下激光条纹中心点的三维坐标。在ZYNQ芯片中实现上述算法的并行加速,进行工件轮廓扫描测试。结果表明:该传感器可得到工件的三维轮廓点云。

DEM质量检验若干问题分析

针对依据《数字测绘成果质量检查与验收》GB/T 18316—2008和《数字高程模型质量检验技术规程》CH/T 1026—2012在DEM高程精度检验中套合差质量评定出现的疑惑、DEM高程精度检查方法与技巧、检测点选择等相关问题进行了一些思考分析,并提出了一些相应的建议,以求引起规范编制部门和广大数字测绘成果检验人员的关注,希望能对提升DEM成果检验质量和检验效率有所帮助。

On the “Onion Husk” Algorithm for Approximate Solution of the Traveling Salesman Problem

The paper describes some implementation aspects of an algorithm for approximate solution of the traveling salesman problem based on the construction of convex closed contours on the initial set of points (“cities”) and their subsequent combination into a closed path (the so-called contour algorithm or “onion husk” algorithm). A number of heuristics related to the different stages of the algorithm are considered, and various variants of the algorithm based on these heuristics are analyzed. Sets of randomly generated points of different sizes (from 4 to 90 and from 500 to 10,000) were used to test the algorithms. The numerical results obtained are compared with the results of two well-known combinatorial optimization algorithms, namely the algorithm based on the branch and bound method and the simulated annealing algorithm. .

Fast Image Segmentation Based on a Two-Stage Geometrical Active Contour

A fast two-stage geometric active contour algorithm for image segmentation is developed. First, the Eikonal equation problem is quickly solved using an improved fast sweeping method, and a criterion of local minimum of area gradient (LMAG) is presented to extract the optimal arrival time. Then, the final time function is passed as an initial state to an area and length minimizing flow model, which adjusts the interface more accurately and prevents it from leaking. For object with complete and salient edge, using the first stage only is able to obtain an ideal result, and this results in a time complexity of O(M), where M is the number of points in each coordinate direction. Both stages are needed for convoluted shapes, but the computation cost can be drastically reduced. Efficiency of the algorithm is verified in segmentation experiments of real images with different feature.

SIMULATION OF TYPHOON'SANOMALOUS TRACK(Ⅱ)──CD METHOD

Contour dynamics (CD) method for the motions of typhoon is presented in this paper. The effect of asymmetric inner structure on the typhoon'sanomalous track has been discussed in different environmental steering. Todemonstrate the feasibility of the method, the track of Typhoon Yancy(9012) isconcerned with. The numerical results show that the method can describe the tendency of looping qualitatively.

Novel boundary element method for resolving plate bending problems

This paper discusses the application of the boundary contour method for resolving plate bending problems. The exploitation of the integrand divergence free property of the plate bending boundary integral equation based on the Kirehhoff hypothesis and a very useful application of Stokes' Theorem are presented to convert surface integrals on boundary elements to the computation of bonding potential functions on the discretized boundary points, even for curved surface elements of arbitrary shape. Singularity and treatment of the discontinued corner point are not needed at all. The evaluation of the physics variant at internal points is also shown in this article. Numerical results are presented for some plate bonding problems and compared against analytical and previous solutions.

Backup roll contour of a SmartCrown tandem cold rolling mill

SmartCrown was a new system developed by VAI for improving the strip profile and flatness control first applied in 1700 mm tandem cold rolling mills at Wuhan Iron ＆ Steel （Group） Corporation （WISCO）. After tracing and testing, the application of the conventional crown backup roll matching the SmartCrown work roll of the production mill led to heavy and nonuniform wear, and the edge spalling of the backup roll often occurred. A 3-dimension finite element model of roll stacks was established, which was used to analyze the above-mentioned problems, and it was found that the main reason was the highly nonuniform contact pressure distribution between the work roll and the backup roll. A new FSR （flexible shape backup roll） was developed and applied in 1700 mm tandem cold rolling mills. A lot of good actual effects of FSR, such as evident improvement in profile and flatness of strips, non-occurring edge spalling, wear uniform, and remarkable decrease in roll consumption were validated by long-term industrial applications.

Fast Texture Segmentation Based on Semi-Local Region Descriptor and Active Contour

In this paper,we present an efficient approach for unsupervised segmentation of natural and textural images based on the extraction of image features and a fast active contour segmentation model.We address the problem of textures where neither the gray-level information nor the boundary information is adequate for object extraction.This is often the case of natural images composed of both homogeneous and textured regions.Because these images cannot be in general directly processed by the gray-level information,we propose a new texture descriptor which intrinsically defines the geometry of textures using semi-local image information and tools from differential geometry.Then,we use the popular Kullback-Leibler distance to design an active contour model which distinguishes the background and textures of interest.The existence of a minimizing solution to the proposed segmentation model is proven.Finally, a texture segmentation algorithm based on the Split-Bregman method is introduced to extract meaningful objects in a fast way.Promising synthetic and real-world results for gray-scale and color images are presented.

New normalized nonlocal hybrid level set method for image segmentation

This article introduces a new normalized nonlocal hybrid level set method for image segmentation.Due to intensity overlapping,blurred edges with complex backgrounds,simple intensity and texture information,such kind of image segmentation is still a challenging task.The proposed method uses both the region and boundary information to achieve accurate segmentation results.The region information can help to identify rough region of interest and prevent the boundary leakage problem.It makes use of normalized nonlocal comparisons between pairs of patches in each region,and a heuristic intensity model is proposed to suppress irrelevant strong edges and constrain the segmentation.The boundary information can help to detect the precise location of the target object,it makes use of the geodesic active contour model to obtain the target boundary.The corresponding variational segmentation problem is implemented by a level set formulation.We use an internal energy term for geometric active contours to penalize the deviation of the level set function from a signed distance function.At last,experimental results on synthetic images and real images are shown in the paper with promising results.

Automatic wiring method for switchgear design

An automatic 3D wiring method for switchgear design is proposed in this paper. First, wiring constraints are created, and a corresponding evaluation model is proposed. Then, based on the structure of the cabinet, we propose a contour expansion scheme to construct rough paths. Different wiring features of the switchgear are used to connect rough local paths. All the paths are represented in a uniform data structure and forma path network. Finally, an improved A* algorithm is used to search the wiring path between the components in the routing network; the evaluation model is considered as heuristic rules for path searching. The result can satisfy the practical requirements of switchgear design. Experimental results are also provided.

Extended Active Contour Algorithm Based on Color Variance

一般活跃轮廓算法，使用图象的紧张，被用来活跃地分割 chjects.Because cbjects 有类似的紧张但是不同颜色，从 others.Moreover 分割任何目标是困难的，自从扩大活跃轮廓 algarithm 基于颜色 variance.In 建筑群想象，对解决这些 problems.This 纸的顺序建议的 noise.In 很敏感，这个算法能仅仅在简单环境被使用。

Numerical simulation of crack propagation by manifold method

In this paper, by means of the maximum circle tensile stress on curve of constant ω and stress intensity factors by a path independent contour integral method, trajectories of maxed mode crack propagation are simulated through numerical manifold method. The crack propagation is traced dynamically by modifying the neighboring connection between the crack-top and nodes within elements in the calculating process. This method has the advantages such as less modified area, easiness of programming, high realizability and so on. Then a single sharp nicked specimen is used to verified the numerical result. It is shown that the provided method is reasonable and effective.