无人机空中加油过程中分数阶滑模会合导引控制

针对带末端角度和末端速度约束的无人机空中加油自主会合问题,设计了一种3维分数阶滑模导引律,使无人机在无加油机主动配合的情况下具备自主会合能力.首先,根据无人机与加油机之间的相对运动关系,设计了3维比例导引规律,使无人机能够到达期望的加油位置.其次,利用滑模控制的强鲁棒性特点以及分数阶微积分的精细控制特性,基于变结构理论和李雅普诺夫稳定性理论设计了一种带有末端角度约束的3维分数阶滑模变结构控制律,并用所设计的分数阶滑模控制律对3维比例导引指令进行重构,使无人机能以期望的末端追踪角度到达加油位置.然后,构造了速度指令生成器,对无人机的末端速度进行约束.最后,对所设计的导引律进行了仿真验证,仿真结果表明所设计出来的导引律能满足追踪角度和速度约束的要求.     

二维圆环结构中弹性波传播的谱单元分析

为研究弹性波在结构中的波场特征,推导建立一种任意四边形二维谱单元,将其应用于二维圆环结构中的波传播行为模拟.以矩形平板结构中弹性导波传播分析为例,通过与传统有限元分析结果对比,验证所建立谱单元的有效性.有裂纹和无裂纹二维圆环结构谱单元模拟结果表明:弹性波在圆环结构中传播会发生频散;圆环结构表面的裂纹对瑞利波的传播影响最大;根据其反射波包位置可以确定损伤位置.     

Modeling of microstrip antennas using neural networks techniques: A review

Artificial neural networks modeling have recently acquired enormous importance in microwave community especially in analyzing and synthesizing of microstrip antennas (MSAs) due to their generalization and adaptability features. A trained neural model estimates response very fast, which is nearly equal to its measured and/or simulated counterpart. Thus, it completely bypasses the repetitive use of conventional models as these models need rediscretization for every minor changes in the geometry, which itself is a time‐consuming exercise. The purpose of this article is to review this emerging area comprehensively for both analyzing and synthesizing of the MSAs. During reviewing process, some untouched cases are also observed, which are essentially required to be resolved for antenna designers. Unique and efficient neural networks‐based solutions are suggested for these cases. The proposed neural approaches are validated by fabricating and characterizing of the prototypes too. © 2015 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:747–757, 2015.     

粒子群算法在武汉市图书馆变风量空调控制系统中的应用研究

以武汉市图书馆公共建筑节能项目为背景,考虑到现有的方法有如下缺点:系统惯性大、时间滞后及单一采用PID控制时,控制效果不好,我们找寻到了一种高效的方法来解决这些缺点,实现优化温度参量来控制。根据变风量空调系统的结构,对变风量系统室内温度控制环节采用粒子群算法,经过Matlab软件进行仿真,使室内温度控制环节的上升时间、超调量及调整时间得以优化。     

一种Android终端控制物联网结点的技术应用

提出了一种对楼宇分体空调进行集中管理的方法,结合物联网的构成及实际应用模式,探索并将其理论方法引入到系统中来,构建了一个基于物联网的分体空调远程集中控制系统。通过Android终端设备,可对系统运行情况进行实时监控和管理。经实验测试验证,该集中控制节点及感知节点的设计满足系统的要求,可靠性高,成本低,功能强。     

富士5000G11S变频器在热风炉助燃风机应用中的问题及解决办法

介绍富士5000G11S变频器在热风炉助燃风机应用中的问题及解决办法.     

Bare finger 3D air‐touch system with embedded multiwavelength optical sensor arrays for mobile 3D displays

A camera‐free 3D air‐touch system was proposed. Hovering, air swiping, and 3D gestures for further interaction with the floated 3D images on the mobile display were demonstrated. By embedding multiwavelength optical sensors into the display pixels and adding angular‐scanning illuminators with multiwavelength on the edge of the display, the flat panel can sense images reflected by a bare finger from different heights. In addition, three axis (x, y, z) information of the reflected image of the fingertip can be calculated. Finally, the proposed 3D air‐touch system was successfully demonstrated on a 4‐inch mobile 3D display.     

Spatial and functional relationships between air conduits and blood capillaries in the pulmonary gas exchange tissue of adult and developing chickens

The documented data regarding the three-dimensional structure of the air capillaries (ACs), the ultimate sites of gas exchange in the avian lung is contradictory. Further, the mode of gas exchange, described as cross-current has not been clearly elucidated. We studied the temporal and spatial arrangement of the terminal air conduits of the chicken lung and their relationship with the blood capillaries (BCs) in embryos as well as the definitive architecture in adults. Several visualization techniques that included corrosion casting, light microscopy as well as scanning and transmission electron microscopy were used. Two to six infundibulae extend from each atrium and give rise to numerous ACs that spread centrifugally. Majority of the ACs are tubular structures that give off branches, which anastomose with their neighboring cognates. Some ACs have globular shapes and a few are blind-ending tapering tubes. During inauguration, the luminal aspects of the ACs are characterized by numerous microvillus-like microplicae, which are formed during the complex processes of cell attenuation and canalization of the ACs. The parabronchial exchange BCs, initially inaugurated as disorganized meshworks, are reoriented via pillar formation to lie predominantly orthogonal to the long axes of the ACs. The remodeling of the retiform meshworks by intussusceptive angiogenesis essentially accomplishes a cross-current system at the gas exchange interface in the adults, where BCs form ring-like patterns around the ACs, thus establishing a cross-current system. Our findings clarify the mode of gas exchange in the parabronchial mantle and illuminate the basis for the functional efficiency of the avian lung.     

EFFECTS OF ENTRAINED AIR MANNER ON CAVITATION DAMAGE

Early in 1953 the experiments by Peterka proved that air entrainment has effects on decreasing cavitation damage.This technology has been widely used in the release works of high dams since the inception of air entrainment in the Grand Goulee Dam in 1960.Behavior,mechanism and application of air entrainment for cavitation damage control have been investigated for over half century.However,severe cavitation damage happened due to complex mechanism of air entrainment.The effects of air entrainment are related...     

引气剂在南水北调中线工程中的应用

引气剂在混凝土中能够引入大量微小、封闭、稳定的气泡,可改善混凝土和易性、耐久性,延长建筑物的使用寿命。引气剂的使用效果与混凝土的原材料质量、拌和工艺及环境有关,使用时应适当调整掺量,满足含气量的技术指标要求。