In Situ Anchoring Ultra Small Au Nanoparticles by Conformal Coating of Carbon Layer within the Micro-Environments of Mesoporous Silica for Highly Efficient Catalytic Reduction of 4-nitrophenol

Catalysis Letters - For the noble-metal based catalysts, the metal dispersion and sinter resistance of the metal nanoparticles (NPs) are the most vital factors for their application in series...     

基于张力观测器的无传感卷绕系统的研究

传送系统中,对带材卷取张力和线速度进行独立控制的优化一直倍受关注。针对卷绕张力控制系统的特点,提出一种运用观测器得到的张力值作为调节器反馈构建张力闭环系统的方案,从而完成无传感器的反馈控制,节省机械设备成本,提高生产线的整体速度,减少传感器信号受干扰对产品质量的影响。仿真结果表明,该系统动态性能良好,而且具有较高的稳态精度。     

基于临界裂纹尖端位移的沥青胶结料抗疲劳性能评价

以G~*·sin δ为代表指标的沥青胶结料疲劳性能评价方法高度依赖动态剪切流变仪,针对该方法所需设备在中国普及率较低且对SBS改性沥青的适用性较差等问题,采用测力延度仪进行双边缺口拉伸试验,提出了以临界裂纹尖端位移(CTOD)作为沥青胶结料常温条件下(0～30℃)抗疲劳性能的评价指标.用CTOD和G~*·sin δ这2个指标对7个沥青胶结料的抗疲劳性能进行排序,并采用四点弯曲疲劳试验从混合料层面对沥青胶结料的抗疲劳性能的排序结果进行验证,最后用显著性检验方法比较了温度对CTOD区分度的影响.结果表明:CTOD与G~*·sin δ对SBS改性沥青的疲劳性能评价存在分歧,四点弯曲疲劳试验得到的混合料疲劳性能与CTOD所表征的沥青胶结料结果更具相关性;显著性检验发现,与15℃相比,25℃的CTOD指标对选用沥青胶结料的区分度更好.CTOD所需试验设备在中国应用较广,有望成为沥青胶结料抗疲劳性能的有效鉴定方法之一.     

UPS电池容量计算方法

以某电厂不间断电源选型为例,介绍了其蓄电池容量的选择原则、计算方法及合理配置,为电气设计师提供参考,以便正确选用合适的产品.     

一种基于分布式融合策略的声定位方法

随着城市环境中对各类目标声检测的需求的发展,开发分布式组网声探测手段越来越有必要。然而对于分布式组网声探测技术,当前的声定位方法对全链路的数据传输依赖程度较高,通信传输会带来巨大的带宽压力和很高的通信成本。因此,本文从能耗的角度研究分布式融合声定位的方法,提出通过分布式位置的声事件能量幅度进行目标的融合定位处理,并通过试验测试进行了可行性验证。验证结果表明,无线声感知网络可以在只接收幅度信息且激发少数节点的情况下实现对目标的定位,定位精度的均方根误差(Root Mean Square Error,RMSE)不大于6 m。     

La1-xSrxCo1-yFeyO3材料制备及结构分析

以溶胶-凝胶法制备La1-xSrxCo1-yFeyO3粉体,对粉体在不同温度热处理后的晶体结构进行XRD表征,详细研究粉体的成分组成以及发生的结构转变.结果表明,凝胶前驱体粉体颗粒比表面增大有利于钙钛矿结构晶相形成;合成粉体受前驱体比表面程度影响形成两种具有不同空间群钙钛矿结构晶相,并且各晶相元素化学计量比不相同,两相体系较稳定.     

民用电网谐波电流检测方法及仿真研究

针对民用电网中存在的电压不稳、三相不平衡和中线电流大等问题,在传统的ip-iq法基础上,采用对称分量法和零序电流分离法研究电流中的零序分量问题,并结合PI调节器建立数学模型对其谐波、基波负序和零序电流进行了实时检测。结果表明,该方法可准确地检测出电网电流中含有的谐波、基波负序和零序电流,且检测精度高、实时性好。     

基于AVR微处理器的钢坯保温车电气系统

为钢坯运输车设计的专用保温罩,其可靠、高效工作有赖于优异的电气控制系统。采用ATMEL公司AVR微处理器为核心,并设计相关接口电路、驱动电路,最后制作出PCB控制板。该控制板能够实现对保温罩的顺序控制、延时控制及故障报警等功能。系统设有用于紧急情况的强制按钮。     

Design,modeling and experimental evaluation of a legged,multi-vectored water-jet composite driving mechanism for an amphibious spherical robot

This paper designs a novel legged, multi-vectored water-jet composite driving mechanism (LMWCDM) for the amphibious spherical robot (ASRobot) and presents modeling and experimental evaluation of this composite driving mechanism. In order to crawl on land flexibly, the robot was designed in SolidWorks and simulated in ADAMS environment with the sit to stand motion and a crawling gait. Then the simulation results, such as driving torques, guided the selection of servomotors in different joints. In aquatic environment, the dynamic modeling of ASRobot was analyzed by synthesizing the propulsive vectors of four propellers in each workspace of legs. Simplistically, multiple underwater locomotion, such as longitudinal and lateral motion, rotary motion, sinking and floating motion and cruising motion, were proposed. Thus, using a six-axis force/torque sensor at the equivalent mass center, a force and torque measuring mechanism was developed to obtain the direct propulsive effect and validate the modeling of the driving system. To evaluate the robot design and selection of servomotors, experiments of the sit to stand motion and crawling motion were conducted. Underwater testing experiments of LMWCDM were carried out to verify the modeling of rotary motion, sinking and floating motion. Besides, underwater test of the robot prototype also proved the highly flexible and swift motion.