Angular velocity observer for attitude tracking on SO(3) with the separation property

This paper studies a rigid body attitude tracking control problem with attitude measurements only, when angular velocity measurements are not available. An angular velocity observer is constructed such that the estimated angular velocity is guaranteed to converge to the true angular velocity asymptotically from almost all initial estimates. As it is developed directly on the special orthogonal group, which completely avoids singularities, complexities, or discontinuities caused by minimal attitude representations or quaternions. Then, the presented observer is integrated with a proportional-derivative attitude tracking controller to show a separation type property, where exponential stability is guaranteed for the combined observer and attitude control system.     

Inertial effects on cylindrical particle migration in linear shear flow near a wall

Micro-/nanoparticle-based systems are regarded as one of the possible candidates due to the engineerability and multifunctionality to maximize the accumulation of the nano-/microparticle-based drug delivery system on the target. Recent advances in nanotechnology enable the fabrication of diverse particle shapes from simple spherical particles to more complex shapes. The particle dynamics in blood flow and endocytosis characteristics of non-spherical particles change as the non-sphericity effect increases. We used a numerical approach to investigate the particle dynamics in linear shear flow near a wall. We examined the dynamics of slender cylindrical particles with aspect ratio γ = 5.0 in terms of particle trajectory, velocity, and force variation for different Stokes numbers over time. We identified the rotating inertia of particle near a wall as the source of inertial migration toward the wall. The drift velocity of slender cylindrical particles is comparable to that of discoidal particles. We discuss the possibilities and limitations of using slender cylindrical particles as a drug delivery system.     

Nonparametric approach for uncertainty-based multidisciplinary design optimization considering limited data

Uncertainty-based multidisciplinary design optimization (UMDO) has been widely acknowledged as an advanced methodology to address competing objectives and reliable constraints of complex systems by coupling relationship of disciplines involved in the system. UMDO process consists of three parts. Two parts are to define the system with uncertainty and to formulate the design optimization problem. The third part is to quantitatively analyze the uncertainty of the system output considering the uncertainty propagation in the multidiscipline analysis. One of the major issues in the UMDO research is that the uncertainty propagation makes uncertainty analysis difficult in the complex system. The conventional methods are based on the parametric approach could possibly cause the error when the parametric approach has ill-estimated distribution because data is often insufficient or limited. Therefore, it is required to develop a nonparametric approach to directly use data. In this work, the nonparametric approach for uncertainty-based multidisciplinary design optimization considering limited data is proposed. To handle limited data, three processes are also adopted. To verify the performance of the proposed method, mathematical and engineering examples are illustrated.     

Easy-to-attach vacuum modules with biochips for droplets generation from small sample volumes

This study developed a droplet biochip driven with a single vacuum module to produce droplets from small sample volumes. The vacuum module is composed of a shape memory polymer, which releases prestored energy for shape recovery when subjected to heat trigger, and works as an easy-to-attach vacuum source. The three-layer Teflon mold is designed to manufacture a vacuum module with a favorable yield (>95%). The water-in-oil emulsion droplets can be produced by attaching a single vacuum module with a microfluidic chip. The diameter of the vacuum module has been successfully reduced to 6 mm. The maximum driving pressure provided by the 15-mm diameter vacuum module attached with a 2 μL chip is approximately 9653 Pa. The produced flow rate varies with the deformation rate of the vacuum module and becomes stable at 2.4 µL/min during the droplet generation. The droplet diameters range from 180 to 240 µm. The developed disposable vacuum module is easy to attach, easy to use, easy to make, cost-effective, and automatically controllable for driving fluids on a chip for handling small sample volumes.     

基于改进光流法的旋转运动背景下对地运动目标实时检测

针对战机对地侦查视频图像中地面旋转运动背景下运动目标检测高虚警、低实时性的问题,提出了一种基于改进光流法的旋转运动背景下对地运动目标实时检测算法。首先提取图像的特征点,在特征点处计算光流运动矢量,并通过光流矢量场估算背景运动矢量。根据战机飞行高度自适应计算目标像素尺寸,网格化分块待检测图像;然后将各个特征点光流矢量与背景运动矢量相比较,获得备选目标特征点。最后统计分块备选目标特征点密度,判断目标位置区域。对2组实验视频中央360像素×432像素区域进行目标检测实验,结果表明该算法能够准确地检测出地面运动目标,虚警率低。平均每帧检测耗时分别为29.460 ms和31.505 ms,满足战机对地运动目标检测的实时性。     

The Double‐Edged Sword: The Effects of Journalists' Social Media Activities on Audience Perceptions of Journalists and Their News Products

As social media become popular news platforms, journalists and news organizations have been keen to capitalize on their potential to build and maintain audiences. However, little is known about the extent to which these efforts may have adverse implications. Based on normative theories, the present study investigates the influence of journalists' social media activities (specifically, self‐disclosure and interaction with other users) on audience perceptions of journalists. An experiment (N = 267) revealed that: Although both journalists' self‐disclosure and interaction positively influenced audience perceptions of the journalists in the personal dimension, interaction negatively influenced audience perceptions in the professional dimension; and the perceptions transferred to perceptions of news products, thereby mediating the relationship between journalists' social media activities and audience news perceptions.     

临桂县小型农田水利奖补政策实践与思考

以奖代补政策是临桂县人民政府为扶持农村水利建设而出台的一项惠民政策,该政策自2011年出台以来已3年多,在给百姓带来诸多收益的同时,也暴露出了许多问题,为此,总结3年以来政策执行情况和实践经验,分析存在问题,提出改进建议。