基于协方差描述子和LogitBoost的交通场景图像分割

针对传统方法直接采用图像特征参与图像分割时存在的特征冗余且分割准确率低的问题，提出了一种基于协方差描述子和LogitBoost的交通场景图像分割方法.采用运动结构特征、纹理和HOG特征描述交通场景，并利用协方差描述子进行特征融合以消除特征冗余；采用多类LogitBoost分类器进行图像分割，提高了交通场景分割的精度.在公共测试视频数据库CamVid中测试和评估了所提出的算法，结果表明了该方法的有效性.     

Congenital supravalvular aortic stenosis in a kitten

A three-month-old, male intact Norwegian forest cat without any clinical signs was referred to the cardiology service of the author’s teaching hospital for evaluation of a cardiac murmur. The murmur was systolic with an intensity of 4 out of 6 with the point of maximal intensity at the left heart base. Echocardiography revealed a moderate mitral valve regurgitation and a moderate dynamic left ventricular outflow tract obstruction both resulting from systolic anterior motion of the mitral valve (SAM). Moreover, left ventricular concentric hypertrophy was noted. Oral atenolol therapy was initiated. Recheck examination 3.5 months later revealed unchanged murmur characteristics in the still asymptomatic kitten. Echocardiography showed no SAM, but there was a severe fixed aortic stenosis apparent caused by a discrete supravalvular lesion, 4 mm distal to the valve, with an hourglass morphology. Supravalvular aortic stenosis is a rare congenital anomaly in cats, which has not been reported antemortem yet.     

农业装备自动控制技术研究综述

随着信息与控制理论的发展，自动化控制技术在农业装备领域广泛应用，促进农业生产的智能化、现代化与规模化。运动控制和作业控制是智能农机自动控制技术的两大核心内容，为无人农机在复杂环境下的高精度自主导航安全行驶和精准作业提供保障。速度控制与转向控制是智能农机运动控制的基础，导航跟踪控制是智能农机运动控制的主要内容。本文阐述了智能农机速度控制与转向控制的研究进展，总结归纳了基于几何模型、基于运动学模型和不依赖于模型的自动导航跟踪运动控制方法。然后，着重分析了智能农机在耕、种、管、收等各环节的作业机构控制以及多机协同作业控制方法。最后，指出构建更加精准的农机数学模型，研究面向复杂场景的先进底盘运动控制技术，发展人工智能与控制理论深度融合的农机控制技术以及提升农机农艺相结合的多机协同控制技术是未来智能农机自动控制技术的发展方向。     

运动副分布顺序对并联机构运动学与动力学性能的影响

根据基于方位特征(POC)的并联机构拓扑设计理论，设计了两种零耦合度且部分运动解耦的三自由度两平移一转动(2T1R)并联机构，它们具有相同运动副类型和数目，但在支链中的分布顺序不同；对这两种机构进行了方位特征、自由度及耦合度等主要拓扑特征分析，并给出其拓扑解析式；根据拓扑特征运动学建模原理，求解了这两种机构的符号式位置正反解，分别分析了两种机构的工作空间和机构发生奇异的条件及奇异位形；根据基于虚功原理的序单开链法对两种机构进行逆向动力学建模，分别求得两种机构的驱动力；对比两种机构运动学与动力学性能，并给出优选机型。给出了优选机型用于水果深加工中智能分拣、输送等应用场景的概念设计。     

基于机器视觉的双圆盘式棉花打顶装置设计与试验

为降低人工打顶的劳动强度，减少化学打顶的环境污染，改善“一刀切”式打顶机构的过打顶情况，通过分析手工打顶过程，设计了一种双圆盘式打顶机构，并基于机器视觉，设计打顶装置单行样机，实现棉花打顶的全程自动化控制。该装置主要由打顶机构、视觉检测机构、运动机构和棉花顶尖识别及控制系统组成。基于棉田调研、结构计算和预试验，确定了打顶装置的整体结构和关键部件尺寸。结合视觉识别研究基础与实际应用，选用YOLO v3算法搭建棉花顶尖识别及控制系统，实现棉花顶尖的识别定位，完成打顶机构的运动控制。以打顶期棉花为研究对象，进行棉花顶尖识别试验、打顶机构性能试验和田间试验，结果表明：棉花顶尖识别试验平均识别率为93%;打顶机构性能试验平均打顶率为94.67%;田间试验平均识别率为85.33%,平均打顶率为78.22%。研究结果可为棉花精准化与智能化打顶的研究提供参考。     

细长果蔬采摘软体气动抓手设计与参数优化

为实现细长果蔬的无损采摘,设计一种充气呈螺旋运动的软体气动抓手.对该抓手进行有限元静力学仿真分析,采用3因素3水平的中心组合设计与响应面分析方法,研究各因素对软体气动抓手螺旋特性的交互影响.以软体气动抓手的螺旋直径和螺距为响应值,分别建立二次回归模型,得到模型的决定系数分别为0.9987和0.9351,各因素对螺旋直径...     

Unmanned aerial systems for modelling air pollution removal by urban greenery

Urban greenery plays an important role in reducing air pollution, being one of the often-used, nature-based measures in sustainable and climate-resilient urban development. However, when modelling its effect on air pollution removal by dry deposition, coarse and time-limited data on vegetation properties are often included, disregarding the high spatial and temporal heterogeneity in urban forest canopies. Here, we present a detailed, physics-based approach for modelling particulate matter (PM₁₀) and tropospheric ozone (O₃) removal by urban greenery on a small scale that eliminates these constraints. Our procedure combines a dense network of low-cost optical and electrochemical air pollution sensors, and a remote sensing method for greenery structure monitoring derived from Unmanned aerial systems (UAS) imagery processed by the Structure from Motion (SfM) algorithm. This approach enabled the quantification of species- and individual-specific air pollution removal rates by woody plants throughout the growing season, exploring the high spatial and temporal variability of modelled removal rates within an urban forest. The total PM₁₀ and O₃ removal rates ranged from 7.6 g m^-2 (PM₁₀) and 12.6 g m^-2 (O₃) for mature trees of Acer pseudoplatanus to 0.1 g m^-2 and 0.1 g m^-2 for newly planted tree saplings of Salix daphnoides. The present study demonstrates that UAS-SfM can detect differences in structures among and within canopies and by involving these characteristics, they can shift the modelling of air pollution removal towards a level of individual woody plants and beyond, enabling more realistic and accurate quantification of air pollution removal. Moreover, this approach can be similarly applied when modelling other ecosystem services provided by urban greenery.     

油葵收获机拨禾板式割台装置研制

针对目前油葵机械化收获存在缺少专用机械设备、籽粒损失率和破损率均较高、收获设备工作性能不可靠等问题,该研究设计了油葵联合收获机拨禾板式割台装置并介绍其结构与工作原理,建立拨禾齿的运动模型,分析拨禾机构运动特性并获取拨禾齿端点的运动轨迹.通过对拨禾齿端点运动轨迹仿真,分析拨禾板转速、机具前进速度与拨禾板圆周数量之间的变化...