并行化退火粒子滤波

本文提出一种基于异构计算的并行化退火粒子滤波方法(P-APF),使用OpenCL框架实现了实时无标记运动跟踪任务。退火粒子滤波过程被分解成若干具有相应粒度的子任务。根据相应的并行度,每个计算任务被分配到标准或附属处理器进行处理,以充分利用OpenCL框架的异构计算能力。提出一种任务时延隐藏策略进一步减少时间消耗。在不同人体运动数据库的实验中,P-APF能在不降低跟踪精度的前提下实现实时处理。时间消耗随着粒子数或视角数目的增加基本保持不变,平均加速比为106。     

现代机械工程中自动控制系统的研究与应用

回顾现代机械工程中自动控制系统的研究历史和研究内容,对进入二十一世纪后自控系统研究中的若干关键技术及其应用做了归纳性介绍,并在揭示科学原理的基础上作出了一些预见性的阐述。     

Design, analysis and control for an antarctic modular manipulator

Antarctic scientific expedition has important strategic significance. It is an inevitable trend to apply robots to assist researchers during the Antarctic expedition. However, the robot manipula- tors at present have a series of problems and unable to meet the requirements of the Antarctic expe- dition. In this paper, a novel Antarctic modular robot manipulator is proposed, which has a compact structure with modular joints. The robot manipulator has high reliability, and quick assembling-and- disassembling ability. Through well wires arranging and thermal controlling, the manipulator can better adapt to the Antarctic environment. In addition, the work space of the manipulator is serious- ly analyzed, and a new hybrid position/force control method is adopted to make the manipulator per- form better. Simulation results validate the control method and show that the robot manipulator has a good performance to meet the requirements of Antarctic expedition.     

超高增压柴油机与斯特林发动机复合运行的分析

本文对超高增压柴油机与斯特林发动机的复合运行进行了初步的探讨,陈述了这种复合运行作为未来发动机技术发展方向之一的可能性。     

对心平顶从动件圆弧拟合的盘形凸轮机构运动规律曲线的研究

利用已导出的对心平顶从动件圆弧拟合的盘形凸轮机构的运动规律公式，绘出运动规律曲线，并分析、比较拟合前后该传动副的运动特性。为评价用多段圆弧拟合、加工机械设计中的盘形凸轮轮廓曲线的优劣开辟了一条新途径。精确地计算出圆弧拟合的凸轮对应从动件的位移、速度、加速度及跃动度在各个位置时的数值，从而能准确地判断圆弧拟合的凸轮代替设计要求的凸轮将会给工作带来我大的性能影响，同时，为我们在拟合时控制该传动副的运动     

Study on the Dynamics of Tribocharged Coal and Mineral Particles in Free-Fall Triboelectric Separator

The dynamics of 2.0?0.8 mm or 0.8?0.5 mm size fraction of tribocharged organic coal, pyrite, and calcite particles were studied under the electric field using the high-speed dynamic camera combined with high-speed motion analysis system. Motion images of these particles were obtained and used to analyze their dynamic parameters. Organic coal particles tribocharged positively move to the negative plate, while pyrite and calcite particles reach the positive plate under the influence of electric force. These results indicate that the trajectories of all 2.0?0.8 mm particles are similar to parabolic curves. For 0.8?0.5 mm particles, the trajectories are approximate straight line, except for the calcite. The vertical velocities of all particles increase with a fluctuant acceleration as a result of gravity and drag force. The horizontal velocities of all particles vary slightly. The dynamics of 0.8?0.5 mm particles prove that size is very important for the triboelectric separation. The actions of electric force and drag force are increased with the decrease of particle size.     

基于十二烷基衣康酸甘油酯的光电双响应传感器

该文制备了一种利用结构色水凝胶作为导电电极的光电双响应传感器。以十二烷基衣康酸甘油酯(DGI)、丙烯酰胺、十二烷基硫酸钠(SDS)、氯化钠等为原料,通过双分子层自组装的方法,制备了结构色水凝胶。将这种结构色水凝胶与传统电容型传感器相结合,得到了光电双响应传感器。采用SEM、LCR数字电桥、拉力试验机、光纤光谱仪等对器件进行了结构、光学、电学及机械性能的表征。结果表明:传感器在拉伸状态(0～100%)和压缩状态(0～60.9k Pa)下,传感器的电容分别变化了31%和44%,其自身颜色在可见光光谱内可以动态可逆地从红色变化到紫色。经历15000次循环拉伸后,传感器性能依旧保持稳定。利用传感器颜色的刺激响应性,传感器在发生形变时,其表面可以清楚地显示出应变源的位置和形状,这样传感器在检测时就可以实现可视化效果。     

Reversible and irreversible domain wall dynamics in [011]C oriented relaxor ferroelectric single crystals

Domain wall motions mainly affect all kinds of properties of ferroelectric materials, such as piezoelectricity, dielectric response, and mechanical loss, and the extrinsic contributions associated with domain wall motions have always been an important issue. In this study, the reversible and irreversible extrinsic contributions to the dielectric properties of [011]_C-oriented 0.27Pb(In_1/2Nb_1/2)O₃-0.46Pb(Mg_1/3Nb_2/3)O₃-0.27PbTiO₃:Mn single crystals have been extracted by the Rayleigh analysis. We found that in the unpoled samples, the extrinsic contributions of reversible and irreversible domain wall motions to dielectric properties significantly reduced, whereas after poling, only the irreversible extrinsic contribution decreased. The pinning effect in the 2R domain structure is much weaker than that in the 4R domain structure, leading to the low enhancement of Q_m and a slight decrease in piezoelectricity caused by acceptor doping in 2R domain structure. This study explores the domain wall dynamics of acceptor-doped single crystals and mainly guides on further performance optimization in PbTiO₃-based relaxor single crystals.     

Origin of superior dielectric and piezoelectric properties in 0.4Ba(Zr0.2Ti0.8)O3–0.6(Ba0.7Ca0.3)TiO3 at intermediate grain sizes

Grain size effect is one of the most important issues to develop next-generation multilayer microdevices. In this work, the tetragonal 0.4Ba(Zr_0.2Ti_0.8)O₃–0.6(Ba_0.7Ca_0.3)TiO₃ (BZT–60BCT) ceramics with a wide grain size from 2.1 to 24 μm were successfully prepared by using ultrafine nano powder and two-step sintering. The results demonstrate that critical/intermediate grain size of dielectric constant ε_r and piezoelectric constant d₃₃ appears at ∼12.9 μm. It was found that the presence of large lattice tetragonality, and enhanced domain wall motion induced by domain coexistence between submicron and nano size in sample with a grain size of ∼12.9 μm, resulting in the superior dielectric and piezoelectric properties. These findings and analyses of the origin of superior dielectric and piezoelectric properties at intermediate grain size have important practical implications in the design of high-performance piezoelectric ceramics.     

Large piezoelectric coefficient with enhanced thermal stability in Nb5+-doped Ba0.85Ca0.15Zr0.1Ti0.9O3 ceramics

Chemical doping is an indispensable tool to tailor the properties of the commercial piezoelectric materials. However, a high piezoelectric coefficient with enhanced thermal stability is rarely achieved by one dopant in some high-performance ferroelectrics, e.g., the recently discovered eco-friendly (Ba_0.85Ca_0.15)(Zr_0.1Ti_0.9)O₃ (BCZT) ceramics. In order to optimize the piezoelectric property in BCZT system by a simple way, we investigated the doping effect of Fe³⁺, Nb⁵⁺ and Bi³⁺ cations in BCZT ceramics respectively. The results indicate that only Nb⁵⁺-doped BCZT ceramics display a combination of large piezoelectric coefficient and enhanced thermal stability, compared with others. Moreover, the established phase diagrams and in-situ transmission electron microscope (TEM) observations reveal that such optimized piezoelectric properties after Nb⁵⁺ doping originates from (i) the low polarization anisotropy near the ambient tetragonal (T)-orthorhombic (O) phase transition and (ii) the easy domain wall motion of persistent miniaturized ferroelectric domains upon heating.