基于角度半径的青年男子躯干部形态相似性匹配

为实现基于三维人体点云的人体形态相似性匹配,文章提出了利用角度半径进行青年男体躯干部轮廓形态描述的方法。先以187名18~25周岁的青年男大学生为研究对象,使用三维扫描法获取其三维点云数据。再通过逆向工程软件识别人体躯干部特征点,截取其正侧面躯干轮廓形态。然后分别建立正侧面躯干部坐标系,提取27个正面角度半径值和60个侧面角度半径值形成三维点云躯干形态数据库。选取14名被试者进行验证,提取的正、侧面角度半径为样本,采用均方根误差法与点云截面数据库进行匹配,并使用OpenCV框架中的MatchSharp法验证匹配结果。结果显示,13名被试者的躯干部正侧面轮廓形态与三维点云轮廓形态匹配成功,准确率达92.86%。研究结果可为三维点云形态相似性分析提供一定的理论基础。

青年男性颈肩部轮廓量化分析与形态匹配

以190名青年男大学生为研究对象,通过照片测量法、三维人体扫描法获取人体正侧面照片及三维点云数据。基于三维点云数据,提取颈肩部轮廓曲线进行椭圆傅立叶拟合得到椭圆系数,经主成分分析和聚类分析,将青年男性颈肩部正侧面形态各分为3类。采用角度半径和欧几里得距离实现二维照片与三维点云数据之间的匹配,并验证匹配准确率。结果显示:颈肩部正面轮廓匹配验证准确率达92.5%,侧面轮廓匹配验证准确率达95.0%。该研究为基于人体照片的人体形态研究提供了理论依据。

基于机器视觉的玉米穗行数自动检测算法设计

该算法主要用于玉米室内考种时穗行数的自动检测。执行时,首先获取玉米穗横断面图像,然后提取出玉米穗的边缘;接着用质心法提取圆心,计算边缘到圆心的距离和角度,在0~2pi上画出一周的角度-半径曲线图;最后对角度-半径曲线图进行最小值滤波器滤波,并统计极小值的个数即是玉米穗的行数。本算法实施成本低,测量玉米穗行数快速、准确、稳定,为机器视觉在玉米考种系统下的应用提供了有效参考。

Influences of fillet radius and draft angle on local loading process of titanium alloy T-shaped components

In order to study influences of geometric parameters on the T-shaped components local loading process, a new mathematical model considering the fillet radius and draft angle was established by using the slab method. The results obtained by the mathematical model agree with the data form experiment and numerical simulation, and the results are closer to the experimental and simulation results. The influence of draft angle may be neglected under the forming conditions used. The influence of fillet radius is notable, especially in the case that the ratio of fillet radius to rib width is less than 0.75.

成形线圈端部成型之探讨

导出了成形线圈端部形状的数学表达式,同时介绍了端部整形模制造过程,从而使成形线圈端部的制造更接近理想状态。

Dropwise Condensation on a Rotating Condenser in Relation to Heat Transfer Intensification

A design of a rotating condenser is suggested. The maximum radius under the effect of rotation is estimated analytically .It is found that it decreases with the angular velocity. This in turn increases the rate of sweeping the surface by departing droplets. The appearance of droplets with smaller radii will be predominant. These small droplets offer small thermal resistances, thus enhancing heat transfer through the condenser surface. It is found also that the maximum radius is a function of the distance from the axis of the rotating condenser. Thus the value of the maximum radius under rotation is not unique. This in turn makes the heat flux through the condenser surface not to be uniform.

Research on spring-back behavior of high strength steel sheets

To investigate the spring-back behavior of dual-phase （DP） steel, V-shape spring-back experiments with different bending angles, relative bending radii and blank holding forces were carried out in this paper. It is concluded that with the increase of V-shape angle or blank holding force, the spring-back of DP steel sheets decreases; while raising fiIlet radius of punch, which has the most apparent effects on spring-back, advances spring-back angle. Among DP590, DP780 and DP980, higher strength yields more notable spring-back due to larger elastic deformation. The difference of spring-back among these materials is relevant with the microstructure and mechanical properties. The total elastic deformation approximately equals the ratio of the strength corresponding to the applied load to the modulus of elasticity.

Kinematic mechanism and path planning of the Essboard

In this paper, we study the kinematic mechanism and path planning for a two-caster nonholonomic vehicle (the Essboard) which is a recent variant of skateboard. Different from the most studied Snakeboard, the Essboard consists of a torsion bar and two platforms, each of which contains a pedal and a caster. We first investigate the relationship between the tilt angles of the pedals and the wheel directions of the casters. This relationship reveals how to control the wheel directions by adjusting the tilt angles. Next, the rotational radius of the Essboard is derived for a given pair of tilt angles of both pedals. The rotational radius of the Essboard is much different than that of the Snakeboard. Then we develop a path-planning algorithm for the Essboard to move from a start position to the goal, using a series of consecutively connected arcs, which are tangent to each other at the connected points. It is shown from a kinematic point of view that the path planning of the Essboard can be solved by a series of pairs of pedals' tilt angles. Three experiments are conducted to confirm the correctness of the main results. The results in this paper are a foundation for further study of the Essboard.

Bending characteristics of dual-hole PM-PCF based on LP_(01) and LP_(11) modal interference

The bending characteristics of dual-hole polarization maintaining photonic crystal fiber(PM-PCF) are demonstrated in this paper. The modal interference is induced by the LP_(01) mode and LP_(11) mode propagating in a single PM-PCF with the same polarization direction. Simulation results demonstrate that the bending radius induces the phase difference between LP_(01) mode and LP_(11) mode, which leads to the change of light interference intensity on the fiber output facet. The relationship between bending radius and normalized interference intensity with three different bending angles is discussed, where the bending angle is defined as the angle between hole axis and the x axis. The bending sensitivity is obtained to be about-188.78/m around the bending radius of 1.5 cm with the bending angle of 90°. The bending characteristics can contribute for online bending detection in widespread areas.