An Improved Torque Sensorless Speed Control Method for Electric Assisted Bicycle With Consideration of Coordinate Conversion

In this paper,we propose an improved torque sensorless speed control method for electric assisted bicycle,this method considers the coordinate conversion.A low-pass filter is designed in disturbance observer to estimate and compensate the variable disturbance during cycling.A DC motor provides assisted power driving,the assistance method is based on the realtime wheel angular velocity and coordinate system transformation.The effect of observer is proved,and the proposed method guarantees stability under disturbances.It is also compared to the existing methods and their performances are illustrated through simulations.The proposed method improves the performance both in rapidity and stability.

Precise conversion between virtual world and real world in stereoscopic imaging

A method for precise conversion between virtual world and real world is put forward in this paper. The method aims to precisely establish the connection between the virtual coordinates and the real coordinates with OpenGL. In the virtual world, two virtual cameras are set to capture the left and right perspective planar images, and coordinates of the planar images can be calculated by the perspective projection model. With coordinates of planar images, coordinates of the stereo- scopic image synthesized in the real world can be calculated by the binocular observation model. Therefore, the corresponding connection between the two systems is established. Experimental re- suits match data from this method well. Therefore, this method can precisely realize the conversion and the interactivity, laying a solid foundation for further study.

Progresses and Prospects of Asymmetrically Coordinated Single Atom Catalysts for Lithium-Sulfur Batteries

Lithium-sulfur batteries(LSBs)are widely regarded as promising next-generation batteries due to their high theoretical specific capacity and low material cost.However,the practical applications of LSBs are limited by the shuttle effect of lithium polysulfides(LiPSs),electronic insulation of charge and discharge products,and slow LiPSs conversion reaction kinetics.Accordingly,the introduction of catalysts into LSBs is one of the effective strategy to solve the issues of the sluggished LiPS conversion.Because of their nearly 100%atom utilization and high electrocatalytic activity,single-atom catalysts(SACs)have been widely used as reaction mediators for LSBs’reactions.Excitingly,the SACs with asymmetric coordination structures have exhibited intriguing electronic structures and superior catalytic activities when compared to the traditional M-N_(4)active sites.In this review,we systematically describe the recent advancements in the installation of asymmetrically coordinated single-atom structure as reactions catalysts in LSBs,including asymmetrically nitrogen coordinated SACs,heteroatom coordinated SACs,support effective asymmetrically coordinated SACs,and bimetallic coordinated SACs.Particularly noteworthy is the discussion of the catalytic conversion mechanism of LiPSs spanning asymmetrically coordinated SACs.Finally,a perspective on the future developments of asymmetrically coordinated SACs in LSB applications is provided.

Donor-acceptor modulation of coordination polymers for effective photothermal conversion

The targeted construction of donor-acceptor(D-A)materials featuring efficient photothermal(PT)conversion properties has been an attractive but challenging goal.Herein,a new series of coordination polymers(CPs)featuring different PT performances were constructed with flexible linker 1,1′-Ferrocenedicarboxylic acid(FCA)and 2,4,6-tri(pyridin-4-yl)-1,3,5-triazine(TPT)as acceptor and donor molecules including coronene and tetrathiafulvalene(TTF).Based on the flexible configurations of FCA ligand and the directing of donor dependent D-A interactions,the structures of TF-1 to TF-3 featuring distinctive dimension were obtained based on Cd(Ⅱ)ions for investigating the PT property in configurational perspectives.A systematic investigation of the PT properties of the CPs was performed.Notably,TF-3 exhibits the finest PT conversion effect under the irradiation of560 nm laser,while TF-2 shows optimal PT conversion under 808 nm laser irradiation required for biological PT therapy,illustrating the correlation between the structural and component features of the CPs and their PT performances.Furthermore,Zn(Ⅱ)as bio-friendly ion was utilized to construct hypotoxic TF-4 that reveals similar structure to that of TF-2 for potential application.Polydimethylsiloxane(PDMS)patches doped with TF-4 exhibits considerable NIR PT conversion effect under808 nm,represented by the nearly 80℃temperature increased in 120 s for TF-4@PDMS patch(1.2 wt%)under 0.9 W cm^(-2)irradiation,the results of which herein indicate the potential of D-A CPs as versatile platform for the modulation of PT materials.

Efficient object location determination and error analysis based on barycentric coordinates

In this paper,we propose an efficient computational method for converting local coordinates to world coordinates using specially structured coordinate data.The problem in question is the computation of world coordinates of an object throughout a motion,assuming that we only know the changing coordinates of some fixed surrounding reference points in the local coordinate system of the object.The proposed method is based on barycentric coordinates;by taking the aforementioned static positions as the vertices of a polyhedron,we can specify the coordinates of the object in each step with the help of barycentric coordinates.This approach can significantly help us to achieve more accurate results than by using other possible methods.In the paper,we describe the problem and barycentric coordinate-based solution in detail.We then compare the barycentric method with a technique based on transformation matrices,which we also tested for solving our problem.We also present various diagrams that demonstrate the efficiency of our proposed approach in terms of precision and performance.

THEORETICAL ANALYSIS OF COORDINATES MEASUREMENT BY FLEXIBLE 3D MEASURING SYSTEM

The system mathematical model of flexible 3D measuring system is built by theoretical analysis, and the theoretical formula for measuring space point coordinate is also derived. Frog-jumping based coordinate transform method is put forward in order to solve measuring problem for large size parts. The frog-jumping method is discussed, and the coordinate transform mathematical model is method of the space point coordinate compared to original value, and an advanced method is provided, Form the space point coordinate transform formula can derive the calculation measuring method for measuring large size parts.

Insight into stable,concentrated radicals from sulfur-functionalized alkyne-rich crystalline frameworks and application in solar-to-vapor conversion

Organic radicals feature versatile unpaired electrons key for photoelectronic and biomedical applications but remain difficult to access in stable concentrated forms.We disclose easy generation of stable,concentrated radicals from various alkynyl phenyl motifs,including 1)sulfur-functionalized alkyne-rich organic linkers in crystalline frameworks;2)the powders of these molecules alone;3)simple diethynylbenzenes.For Zr-based framework,the generation of radical-rich crystalline framework was achieved by thermal annealing in the range of 300-450℃.For terminal alkynes,electron paramagnetic resonance signals(EPR,indicative of free radicals)arise after air exposure or mild heating(e.g,70℃).Further heating(e.g.,150℃for 3 h)raises the radical concentrations up to 3.30 mol kg^(-1).For more stable internal alkynes,transformations into porous radical solids can also be triggered,albeit at higher temperatures(e.g.,250-500℃).The resulted radical-containing solids are porous,stable to air as well as heat(up to 300-450℃)and exhibit photothermal conversion and solar-driven water evaporation capacity.The formation of radicals can be ascribed to extensive alkyne cycliza-tions,forming defects,dangling bonds and the associated radicals stabilized by polycyclicπ-systems.

基于GIM技术的输变电工程三维基础设计场景构建

为提升输变电工程三维基础设计场景构建效率,提出基于GIM技术的输变电工程三维基础设计场景构建。通过无人机扫描目标区域的环境信息,运用Grid建模方法生成三维地形图。以电网信息模型技术为核心,设计三维参数化建模方法,通过调整参数值,快速编辑输变电工程本体结构。经过坐标系转换,将输变电本体结构放置于三维地形场景内,合成输变电工程三维基础设计场景。再通过LOD细节模型,实现可视化三维场景的高效渲染。实验结果显示:应用所提方法构建三维场景模型耗费时间为21.5 min,较其他方法构建耗时最高降低了70.22%,效率得到了很大程度的提高,具有较为优越的应用性能。

Review of Conversion of Farmland to Forests Project:Ranking First in Investment in the World

The Conversion of Farmland to Forests Project (CFF) is one of the six great forest ecological Projects inChina and one of the ten great forest ecological Projects in the world, ranking the third in overall scale and the first ininvestment. CFF was officially initiated in 2002, covering 1897 counties (county-level cities and districts) in 25provinces (autonomous regions or municipalities) of China. The whole investment is more than 40 billion US$ duringabout 20 years (from 1999 to 2017), aiming to form better ecology system in fragile ecology regions and effectivelycontrol the soil and water erosion of the Yangtze and the Yellow River and sandstorm of the Three-north Regions inChina. The experimental Project of CFF began in 1999, including Sichuan, Shanxi and Gansu province, and the scopeof CFF was widened later. About 1.16 million ha of farmlands were converted to forestlands, and one million ha ofplantation in mountains and wasted lands were completed in 3 years, involving 20 provinces (autonomous regions andmunicipalities), 400 counties, 27 thousand villages, 5.7 thousand towns, 4.1 million farm families and 16 millionfarmers.

Practical Application of Participatory Approach in Land Conversion Project Planning: A Case in Quxian County, Sichuan Province

Application of participatory approaches in governmental forestry projects is a bran-new forestry design method. The purpose is to plan the utilization of land correctly, and to determine planting sites, planting species, participating households and management models, based on the projects' requirements and the farmers' demands. Participatory approaches are now practiced in some of the counties in Land Conversion Project. The paper presents the significance and necessity of practicing community mechanis...

Farmland to Forest Conversion Suspended

Due to a lack of farmland,a reforestation project in its eighth year has been tem- porarily suspended

含垃圾能源化处理及电动汽车负载的区域综合能源系统协调优化

传统能源系统互相独立、欠缺联动,容易导致能量的浪费,并且能源结构也难以优化。区域综合能源系统具备多能互补、高效利用的优点,是提高能源利用效率和环保性的重要改进技术。为了利用垃圾蕴含的能量和电动汽车负载端的能源消纳,文中建立一个考虑垃圾焚烧和电动汽车负载的区域综合能源系统模型,利用模型进行系统的优化调度研究。论文分析了系统内的多能源能量流通关系,而后对系统内的各种能源转换设备及电动汽车进行分析,引入垃圾能源化处理,将热能转化为电能,并利用电动汽车进行电能消纳的模式,得出区域综合能源系统的能源效益最大化的模型。通过python进行算例分析,结果表明,含垃圾处理和电动汽车参与的区域综合能源系统既能提高能源的利用效率,又能带来更优的经济效益。

Comparison between Chinese Supervision Enterprise and International Project Management Enterprise

With the entrance into WTO, the Chinese supervision enterprises face the serious challenge never existed before. Comparing with other type enterprises Chinese supervision enterprises nature of China are the same as project management companies in connotation and service scope in nature. They have much superiority in development of the project management work. Through comparing and analyzing the special feature between Chinese supervision enterprise and international project management enterprise, this paper points out the gap between them, and table the proposal of they transforming to the project management enterprises.

CR导联心电图的原理及临床应用

目的探讨CR导联心电图的原理及临床应用。方法CR导联系统是有共同负极的双极胸导联系统,其共同负极是右上肢(R),正极是胸部某点(C),多选V导联各点。获取CR导联心电图的方法有两种:一是利用常规心电图机实采,四个肢体电极全接右上肢,胸导联电极正常连结;二是基于常规心电图数据通过导联转换获取,首先调取aVR、V_(1)-V_(6)、V_(3R)-V_(5R)、V_(7)-V_(9)等导联的原始数据,再利用固定的转换系数CR-V_(i)=V_(i)-2/3 aVR计算目标导联(使用Python语言在Pycharm编译环境下实现算法),最终转换完成后画图。结果实采法与转换法获取了相同的CR导联心电图,但与相应的Wilson导联心电图相比,左胸导联的CR导联心电图形态类似而波幅略大,右胸导联CR导联心电图与Wilson导联心电图波幅相近但形态截然不同:前者P波清晰,QRS波群主波向上、无宽深的Q波,T波直立;后者P波较低,QRS波群主波向下,可出现非梗死性宽深Q波及非缺血性T波倒置,即所谓的右心室盲区。结论CR导联心电图开放了右心室盲区,实现了对左、右心室的平等探测,为临床提供了更有价值的心电学形态信息,弥补了Wilson胸导联系统的不足,值得推广普及。

双目立体视觉下破损黑陶三维重建方法仿真

在三维重建过程中,由于受环境光线变化、物体透明度、遮挡等因素影响,导致重建结果不准确或不完整,使得视觉效果较差。为了提高三维重建精度,提出一种基于双目立体视觉的破损黑陶三维重建方法。通过转换世界-相机-图像-像素坐标系,标定双目立体视觉相机内外参数,引入最小生成树方法立体匹配左右图像对,计算图像像素绝对强度、梯度、匹配截断值对黑陶重建曲面平滑度的影响,得到连续稠密的视差图,使用最小二乘曲线拟合法平滑处理黑陶三维点云数据,将游离在曲面外的点映射到曲面中,通过三角剖分实现破损黑陶三维表面重建。实验结果表明,所提方法能够有效提高重建后黑陶表面平滑度,且重建结果尺寸精准,拟合度高。

海洋油膜偏振反射特性仿真与测试

为了海洋溢油的检测与识别,在偏振特性建模中综合考虑天空的偏振辐射、油膜表面的动态反射、接收探测器的姿态和性能,进行全数字仿真,开展外场动态水面的实测,进行油膜偏振半实物仿真,最后对海洋溢油进行了偏振测试与分析。试验结果表明:在区分油品方面,汽油和水的强度差值为29.33%,线偏振度差值为0.97%,二者结合可较好的分辨溢油。

基于环形阵列的油管损伤三维成像检测方法研究

传统的瞬变电磁套管损伤检测技术是通过采集数据来反映套管损伤情况的二次场信息,反演套管二维壁厚曲线,为套管损伤提供解释依据。为了使套管损伤解释得更加高效、直观、精准,满足井口油管三维成像的需求,建立一种基于环形阵列式的井口油管三维成像检测系统,利用探测仪器中环形阵列分布的TMR传感器,对井口油管各个方位的信息进行采集,使得采集到的数据能够描述不同深度、不同角度的损伤情况。结合套管半径、涡流扩散时间以及径向探测角度之间的关系,通过对井口三维数据的处理,实现套管内外壁三维成像,进而实现井口油管的非对称损伤解释。通过与传统的电磁探伤曲线的对比,验证了所提井口油管三维成像检测方法的有效性,为现场套管损伤解释工作提供重要依据。

倾斜摄影三维模型中水域空洞的自动识别与修复

水域具有独特的光学反射特性,在倾斜摄影测量数据生成的模型中易导致空洞产生。为保证三维模型的完整性和显示效果,需要对水域空洞进行识别与修复。由于倾斜摄影模型内部存在大量独立的几何体,采用常规的三角网拓扑关系提取水域空洞轮廓线时会提取出所有几何体的边界轮廓线,导致无法准确识别水域空洞边界。针对此问题,本文提出了一种基于坐标转换和图像边缘检测获取水域空洞轮廓线的新方法:首先,根据OSGB模型中Z轴方向上是否存在三维点绘制水域空洞二值图,并对二值图像进行边缘检测获取水域空洞的二维轮廓线;再通过坐标转换获取水域空洞的三维轮廓线,对三维轮廓线进行约束构网、纹理映射,得到水域空洞的几何体并将绘制的水域几何体切割融合到不同的模型文件;最终实现水域空洞轮廓的自动识别以及水域空洞的自动修复。

基于双目结构光的三维立体电路板焊点定位

三维立体电路将传统二维集成电路拓展至三维,在提高了电路板形状设计柔性的同时,也提升了电路板上元器件焊点定位的复杂度.为了降低三维立体电路加工过程中的人力成本,提高加工效率,设计了一种用于焊接机床对三维立体电路板焊点定位的双目结构光系统,并针对双目结构光系统在与焊接机床结合应用过程中存在的坐标转换、焊点识别困难等问题,从硬件与算法层面提出了解决方案.在软硬件的配合下,可以简单快速地完成双目结构光系统与焊接机床之间的坐标转换,并对电路板焊点完成定位与坐标计算,代替了人工对三维立体电路板焊点测量定位的复杂流程.实验表明,提出的方案具有较高的精度,能够满足机床焊接元器件过程中对焊点的定位需求.

海上高速航行船舶触礁距离实时计算方法

为了提高船舶航行安全性,并应对航行过程潜在碰撞风险,提出海上高速航行船舶触礁距离实时计算方法。通过航海雷达探测船舶航行环境中的礁石目标,确定极坐标系下的位置坐标后,将其转换地心垂直坐标系下,构建基于PLSTM-FCN的船舶航迹预测模型,从船舶自动识别系统中获取高速航行船舶历史位置、航速、航向、船舶长度、宽度以及吃水深度等AIS数据,将其作为模型输入,模型输出为船舶航行实时位置预测结果,结合礁石目标位置,完成触礁距离的实时计算。实验结果表明,该方法可预测船舶航行航迹,预测MSE值仅为0.002 2;可实现船舶触礁距离的实时计算,计算结果与实际距离误差介于0.77~1.55之间。