Damping Effect on Waves Propagating Past a Submerged Horizontal Plate and a Vertical Porous Wall

A set of analytical solutions for waves propagating past a combined submerged horizontal plate and vertical porous wall breakwater system is presented. The wave damping effect caused by the horizontal plate induced flow constriction is considered in the analysis. The velocity potentials in each fluid domain are derived based on the linear wave theory and the unknown coefficients are determined from the matching conditions using three sets of orthogonal eigenfunctions. Reflection and transmission coefficients are presented to evaluate the performance of the breakwater system. The analytical solutions in terms of the reflection and transmission coefficients as well as the hydrodynamic force on the vertical porous wall are found in good agreement with published laboratory measurements. In comparison with the solutions without taking into account the wave damping effect, the present analytical solutions significantly improve the accuracy of the wave predictions, especially for the reflected waves.     

熔渗CuW材料的超声无损探伤研究

以CuW材料为例，研究其组织中缺陷的超声无损探伤方法。在分析了CuW材料的组织及缺陷特点后，认为多次反射法比较适合，据此对探头频率、对比试块的结构、探伤灵敏度等参数和评价方法进行了研究。结果表明：探头型号5p10的检测效果最好，最佳的检测灵敏度为厚度10mm三次底波至满屏80％高度时对应的灵敏度，对不同牌号的CuW材料可以通过调整检测灵敏度，参照同一标准进行评价。     

营口车探伤设备改造及探伤检验

该超声波探伤设备经更新探伤仪器、更换控制柜和电机、加长水箱及增加探头等技术改造，达到改单探头探伤为双探头探伤，实现无级调速，按GB／T5777-95标准的C5级验收，系统综合性能指标符合YB4082-2000标准规定的要求，为军工航空用小规格薄壁管提供可靠的超声波检测手段。     

Comparison of Particle Size Distributions Measured Using Different Techniques

In this article, particle size distributions (PSDs) measured by different techniques, including image analysis (IA), laser diffraction (LD), ultrasonic attenuation spectroscopy (UAS), and focused-beam reflectance measurement (FBRM), are compared for spherical glass beads and nonspherical silica flakes. It is shown that particle shape strongly affects the results obtained by different techniques. For spheres, the PSDs obtained by IA, LD, and UAS agree well. There is no consistent result among different particle measurement techniques for nonspherical particles. The conversion between PSDs obtained by IA, LD, and UAS has been based on particle shape factors. Caution must be exercised when a measured chord length distribution (CLD) is used to indicate the PSD during a process because the CLD result obtained by FBRM is complex, depending not only on the PSD, but also on particle optical properties and shape.     

室内移动机器人超声传感器导航网络分布研究

对于室内广域移动机器人,超声波传感器网络是能够保证给定导航准确度的一种有效方法。合理的超声波传感器网络分布是实现超声波网络导航的重要条件。论述了超声波网络合理分布的原则,据此提出并分析了获得合理超声波传感器网络分布的四个步骤,仿真试验结果验证了它的有效性。     

A new separation result for a class of quadratic-like systems with application to Euler-Lagrange models

A separation result for some kind of global stabilization via output feedback of a class of nonlinear systems, under the form of some stabilizability by state feedback on the one hand, and some unboundedness observability on the other hand is presented. They allow to design, for any domain of output initial condition, some dynamic output feedback controller achieving global stability. It is also highlighted how disturbance attenuation can further be achieved on the same basis. As an example, the proposed conditions are shown to be satisfied by the class of so-called Euler-Lagrange systems, for which a tracking output feedback control law is thus proposed.     

斜面焊口超声波探伤中的缺陷定位

详细介绍了在斜面焊口超声波探伤中采用声程调节扫描比例进行缺陷定位的计算方法，并给出了计算公式。     

Disturbance Attenuation and Trajectory Tracking via a Reduced-order Output Feedback Controller for Robot Manipulators

This paper presents a solution to the problem of trajectory tracking with external disturbance attenuation in robotics systems via a reduced-order output feedback controller, without velocity measurement. The proposed control law ensures both semi-global asymptotic stability of the closed-loop system and external disturbance attenuation. The approach is based on the notion of the L₂-gain and requires to solve two algebraic Riccati inequalities. The proposed controller design is illustrated by a simulation example.     

基于小波变换的超声电机启动和关断特性的测试与分析

叙述了本研究中心研发的超声电机瞬态测试系统及其测试方法。由于噪声的影响，启动、关断响应曲线常常不太光滑，以往采用平滑技术和数字滤波等处理办法，获得启动和关断响应特性精度较差。本文利用小波变换对原始启动、关断响应数据进行分析，去除噪声，从而较准确地获得了超声电机启动和关断的响应时间。实验结果表明，超声电机确实具有毫秒级的响应时间。     

移动机器人的超声模糊避障算法

超声传感器是移动机器人避障常用的传感器．但存在幻影的干扰。该文提出多个超声传感器的模糊避障算法．该算法把多个超声传感器分为左右两组．如果障碍物在右侧．机器人就向左转，反之机器人向右转。实验表明．该文提出的算法可以实现机器人的安全避障。