Two-Staged Method for Ice Channel Identification Based on Image Segmentation and Corner Point Regression

Identification of the ice channel is the basic technology for developing intelligent ships in ice-covered waters,which is important to ensure the safety and economy of navigation.In the Arctic,merchant ships with low ice class often navigate in channels opened up by icebreakers.Navigation in the ice channel often depends on good maneuverability skills and abundant experience from the captain to a large extent.The ship may get stuck if steered into ice fields off the channel.Under this circumstance,it is very important to study how to identify the boundary lines of ice channels with a reliable method.In this paper,a two-staged ice channel identification method is developed based on image segmentation and corner point regression.The first stage employs the image segmentation method to extract channel regions.In the second stage,an intelligent corner regression network is proposed to extract the channel boundary lines from the channel region.A non-intelligent angle-based filtering and clustering method is proposed and compared with corner point regression network.The training and evaluation of the segmentation method and corner regression network are carried out on the synthetic and real ice channel dataset.The evaluation results show that the accuracy of the method using the corner point regression network in the second stage is achieved as high as 73.33%on the synthetic ice channel dataset and 70.66%on the real ice channel dataset,and the processing speed can reach up to 14.58frames per second.

ELLIPTIC EQUATIONS IN DIVERGENCE FORM WITH DISCONTINUOUS COEFFICIENTS IN DOMAINS WITH CORNERS

We study equations in divergence form with piecewise Cαcoefficients.The domains contain corners and the discontinuity surfaces are attached to the edges of the corners.We obtain piecewise C^(1,α) estimates across the discontinuity surfaces and provide an example to illustrate the issue regarding the regularity at the corners.

Topological laser on square lattice with gain–loss-induced higher-order corner modes

We investigate the higher-order topological laser in the two-dimensional(2D) coupled-cavity array. By adding staggered on-site gain and loss to the 2D Hermitian array with a trivial phase, the system will emerge degenerate topological corner modes, which are protected by bulk band gap. For such a non-Hermitian model, by adjusting the parameters of the system and introducing the pumping into the cavity at the corner, a single-mode lasing with topological protection emerges.Furthermore, single-mode lasing exists over a wide range of pumping strengths. No matter where the cavity is initially stimulated, after enough time evolution, all the cavities belonging to the topological corner mode can emit a stable laser.

An angular blinking jamming method based on electronically controlled corner reflectors

Passive jamming is believed to have very good potential in countermeasure community.In this paper,a passive angular blinking jamming method based on electronically controlled corner reflectors is proposed.The amplitude of the incident wave can be modulated by switching the corner reflector between the penetration state and the reflection state,and the ensemble of multiple corner reflectors with towing rope can result in complex angle decoying effects.Dependency of the decoying effect on corner reflectors’radar cross section and positions are analyzed and simulated.Results show that the angle measured by a monopulse radar can be significantly interfered by this method while the automatic tracking is employed.

Higher-order topological corner states and origin in monolayer LaBrO

Intrinsic higher-order topological insulators driven solely by orbital coupling are rare in electronic materials.Here,we propose that monolayer LaBrO is an intrinsic two-dimensional second-order topological insulator.The generalized second-order topological phase arises from the coupling between the 5d orbital of the La atom and the 2p orbital of the O atom.The underlying physics can be thoroughly described by a four-band generalized higher-order topological model.Notably,the edge states and corner states of monolayer LaBrO exhibit different characteristics in terms of morphology,number,and location distribution under different boundary and nanocluster configurations.Furthermore,the higher-order topological corner states of monolayer LaBrO are robust against variations in spin-orbit coupling and different values of Hubbard U.This provides a material platform for studying intrinsic 2D second-order topological insulators.

Topological edge and corner states of valley photonic crystals with zipper-like boundary conditions

We present a stable valley photonic crystal(VPC)unit cell with C_(3v)symmetric quasi-ring-shaped dielectric columns and realize its topological phase transition by breaking mirror symmetry.Based on this unit cell structure,topological edge states(TESs)and topological corner states(TCSs)are realized.We obtain a new type of wave transmission mode based on photonic crystal zipper-like boundaries and apply it to a beam splitter assembled from rectangular photonic crystals(PCs).The constructed beam splitter structure is compact and possesses frequency separation functions.In addition,we construct a box-shaped triangular PC structures with zipper-like boundaries and discover phenomena of TCSs in the corners,comparing its corner states with those formed by other boundaries.Based on this,we explore the regularities of the electric field patterns of TESs and TCSs,explain the connection between the characteristic frequencies and locality of TCSs,which helps better control photons and ensures low power consumption of the system.

Numerical Study of Co-flow Jet Control on Corner Separation in Compressor Cascade

The design objectives of modern aircraft engines include high load capacity,efficiency,and stability.With increasing loads,the phenomenon of corner separation in compressors intensifies,affecting engine performance and stability.Therefore,the adoption of appropriate flow control technology holds significant academic and engineering significance.This study employs the Reynolds-averaged Navier-Stokes(RANS)method to investigate the effects and mechanisms of active/passive Co-flow Jet(CFJ)control,implemented by introducing full-height and partial height jet slots between the suction surface and end wall of a compressor cascade.The results indicate that passive CFJ control significantly reduces the impact of corner separation at small incidence,with partial-height control further enhancing the effectiveness.The introduction of active CFJ enables separation control at large incidence,improving blade performance under different operating conditions.Active control achieves this by reducing the scale of corner separation vortices,effectively reducing the size of the separation region and enhancing blade performance.

转子尖部角区分离对高负荷压气机性能影响的实验与数值研究

为了探究转子尖部角区分离对高负荷压气机性能及内部流场的影响,以设计负荷系数为0.46的单级高负荷压气机为研究对象,通过实验与数值计算研究了转子叶尖间隙为0.6%与1.3%叶高的两种情况下高负荷压气机级特性与内部流场细节,分析了转子尖部角区分离对于高负荷压气机性能的影响规律及其流动机制。结果表明,转子叶尖间隙为0.6%叶高时,小流量工况下转子尖部吸力面出现了明显的角区分离;而转子叶尖间隙为1.3%叶高时,小流量工况下转子尖部流动由泄漏流主导。随着小间隙下转子尖部角区分离的增强,转子尖部堵塞与损失剧烈增长;同时,由于转子吸力面径向迁移的增强,小流量工况下转子近轮毂区域损失降低、负荷升高。相应地,压气机级总压升随流量减小表现出“先平缓,再升高,最后快速下降”的特点,级效率随着小流量工况总压升的进一步升高快速下降。

基于三点矢量法的转角焊缝焊接轨迹规划

为解决带转角焊缝焊接中机器人示教步骤复杂问题,提出一种基于三点矢量法的转角焊缝焊接轨迹规划方法。首先,根据示教起点、转角顶点、终点和用户输入的圆弧半径,利用空间矢量法将焊缝分为五段,并修正圆弧半径,进而规划各段焊缝焊接插补路径;其次,根据焊接工艺要求,采用旋转矢量法规划焊枪姿态。在处理可能的内侧转角焊缝空间狭窄问题时,应用极限碰撞理论获取焊枪安全角度,以进一步调整焊枪姿态;最后,结合焊接路径规划和焊枪姿态规划,得到完整焊接轨迹。仿真和实验结果表明,该算法简化了机器人示教操作,提高了焊接效率,实现了安全焊接。实践证明,该算法适用于实际焊接工作。

Intel Knights Corner的结点级内存访问优化

传统编程优化(Traditional Programming Optimization,TPO)在Intel Knights Corner(KNC)上收效甚微,因此提出内存访问优化(Memory Access Optimization,MAO)。将MAO应用到已经过TPO的程序Diffusion 3D上,发现其性能仍然提高了39.1%。主要有2个贡献:1)提出MAO,认为TPO+MAO有助于在KNC上获取最优化性能;2)发现对于stencil代码,基于intrinsic的MAO比基于编译器的MAO更高效。这些发现对于在KNC上优化大规模应用有启发意义。

An Incremental Algorithm for Non-Slicing Floorplan Based on Corner Block List Representation

We present a novel incremental algorithm for non-slicing floorplans based on the corner block list representation. The horizontal and vertical adjacency graphs are derived from the packing of the initial floorplanning results. Based on the critical path and the accumulated slack distances we define,we choose the best position for insertion and do a series of operations incrementally, such as deleting modules, adding modules, and resizing modules quickly. This incremental floorplanning algorithm has a very high speed less than 1μm,which is one of the most important measures in this research. The algorithm preserves the original good performances on area and wire length. It can also supply other tools with good physical estimates for area, wire length, and other performance guidelines.

TOOL PATH OPTIMIZATION OF POCKET CORNER

In milling around sharp corners, residual materials are left at sharp corners when the stepover is extremely long in the contour-parallel tool path. Milling force at the sharp corner rises momentarily due to the increase of the cutter contact length, thus shortening the tool life and leading to machine chatter, even cutter breakage. Then a tool path improvement method by inserting biarc transition segments in the contour-parallel tool path is proposed for milling the pocket. Using the method, the cutter moves along the biarc transition tool path. And the corner material is removed. The improved tool path is continuous for clearing residual materials at the sharp corner. Finally, the machining experiment validates the proposed method.

NEW CORNER DETECTION ALGORITHM BASED ON MULTI-FEATURE SYNTHESIS

Corner detection is a chief step in computer vision. A new corner detection algorithm in planar curves is proposed. Firstly, from the human perception, two key characteristics are given as an amendment of the traditional corner properties. Based on the two properties, the concept of the fuzzy set is introduced into a detection. Secondly, the extracted-formulae of three groups including the features of the corner subject degree are derived. Through synthesizing the features of three groups, the judgments of the corner detection, location, and optimization are obtained. Finally, by using the algorithm the detection results of several examples and feature curves for some interested parts, as well as the detection results for the test images history in references are given. Results show that the algorithm is easily realized after adopting the fuzzy set, and the detection effect is very ideal.

随机地图下改进A^(*)路径规划算法研究

为解决传统算法在规划AGV(automated guided vehicles)路径时存在的节点多、路径不平滑和拓展范围广等问题,提出了一种改进A*算法。首先,采用栅格法建立环境信息;其次,通过加权后的障碍物比例对启发函数进行改进,同时增加防碰撞函数以降低碰撞概率;最后,对所提出的改进算法进行拐角优化,减少AGV实际作业时的转弯次数。实验数据表明,简单环境下改进A^(*)算法的遍历节点数较两种传统算法分别缩短了85.3%、55.9%;复杂环境下改进A*算法的遍历节点数较两种传统算法缩短94.5%、70.3%。同时拐点数量减少、路径更加平滑、路径规划时间也大幅缩短,提高了运行效率并有效降低碰撞概率。

A Gridless Router Based on Hierarchical PB Corner Stitching Structure

A multi layer gridless area router is reported.Based on corner stitching,this router adopts tile expansion to explore path for each net.A heuristic method that penalizes nodes deviating from the destination is devised to accelerate the algorithm.Besides,an enhanced interval tree is used to manage the intermediate data structure.In order to improve the completion rate of routing,a new gridless rip up and rerouting algorithm is proposed.The experimental results indicate that the completion rate is improved after the rip up and reroute process and the speed of this algorithm is satisfactory.

小方坯弧形结晶器水口位置优化设计

鉴于某厂150mm×150mm方坯角部纵裂,对弧形结晶器的流场和温度场进行了数值模拟。设计了水口在中心位置水平偏移和偏转的7种方案。通过对比流场对称性和温度分布均匀性,发现水口向内弧偏转0.5°~1.0°或向内弧偏移5mm的方案获得的流场对称性和温度分布均匀性最好,方坯角部纵裂明显减少。

GRAPH GRAMMAR METHOD FOR 3-D CORNER DETECTION

Most of local feature descriptors assume that the scene is planar. In the real scene, the captured images come from the 3-D world. 3-D corner as a novel invariant feature is important for the image matching and the object detection, while automatically discriminating 3-D corners from ordinary corners is difficult. A novel method for 3-D corner detection is proposed based on the image graph grammar, and it can detect the 3-D features of corners to some extent. Experimental results show that the method is valid and the 3-D corner is useful for image matching.

切角措施对串列方柱气动性能影响的大涡模拟研究

串列双方柱的干扰效应受方柱气动外形的影响显著,方柱角部形状的变化将导致周边流场的改变,进而影响上、下游方柱的气动性能,串列双方柱的风荷载干扰效应相关影响及机理还有待进一步研究。本文采用基于空间平均的大涡模拟方法,以亚临界间距比和超临界间距比的串列方柱为对象,分别对上、下游方柱考虑有、无切角(切角率均为10%)两种情况,研究两类典型间距比下不同切角措施对串列方柱风荷载的影响及其机理。将标准串列方柱风压系数与风洞试验结果对比,验证本文模拟方法及参数设置的有效性;从气动力系数统计值及自谱、平均和脉动风压系数分布等角度,对比分析了两种典型间距比下不同切角措施对串列双方柱气动性能的影响,着重从时均和瞬态流场角度进行机理分析。结果表明,两种典型间距比下,不同位置的切角措施均会影响方柱周围流动分离,从而引起流态变化,其中上、下游方柱均采取切角措施,可以更有效地减弱方柱的平均和脉动风荷载。

Dialogues Among Civilizations and Cultures

Mutual learning is a cornerstone for building a global community of shared future.Cultural Envoys:Connecting Civilizations introduces the winners of the Orchid Awards,a recent laurel instituted by the China International Communications Group to recognize the work of people worldwide who have made significant contributions to cultural exchanges and mutual learning between China and the rest of the world.

某汽车发罩外板零件冲压开裂原因分析及治理研究

针对某汽车发罩外板冲压开裂问题,采用电子拉伸试验机、体视显微镜、金相显微镜、扫描电镜和能谱分析仪等设备对材料的力学性能、成分组织进行检测,采用AUTOFORM冲压成形仿真软件分析模具圆角半径、表面摩擦系数等因素对零件成形效果的影响。结果表明,材料性能优良,但零件成形开裂的主要原因是对应部位的模具上下棱线圆角半径偏小、模具表面摩擦系数较大。通过打磨光滑模具上下棱线圆角、对模具表面进行镀铬处理等措施,降低了材料流动阻力,材料变形更加均匀,使该汽车发罩外板零件冲压开裂问题得到了解决。