Damage characteristics and surface description of near-wall materials subjected to ultrasonic cavitation

For the analysis of ultrasonic cavitation erosion on the surface of materials, the ultrasonic cavitation erosion experiments for AlCu4Mg1 and Ti6Al4V were carried out, and the changes of surface topography, surface roughness, and Vickers hardness were explored. Cavitation pits gradually expand and deepen with the increase of experiment time, and Ti6Al4V is more difficult to erode by cavitation than AlCu4Mg1. After experiments, the cavitation damage characteristics such as the single pit, the rainbow ring area, the fisheye pit, and some small pits were observed, which can be considered to be induced by a single micro-jet impact, ablation effect caused by the high temperature, micro-jet impingement with a sharp angle, and multibeam micro-jets coupling impact or negative pressure in the local area produced by micro-jet impact, respectively. The surface roughness and Vickers hardness of the material increase slowly after rapid growth at different points in time as the experiment time increases. With the increase of the ultrasonic amplitude, both of them first increase and then decrease after the ultrasonic amplitude is greater than 10.8 μm. The increases in surface roughness and Vickers hardness tend to decrease as the viscosity coefficient increases. Ultrasonic cavitation can cause submicron surface roughness and increase surface hardness by 20.36%, so it can be used as a surface treatment method.     

Measurement and simulation of sand saltation movement under fluctuating wind in a natural field environment

Extensive research on the near surface movement of sand particles has focused on wind tunnel experiments, theoretical analysis, and numerical simulation of sand saltation under ideal and controllable conditions. Most field observations are results on the average rate of sand transport over some hours or the whole day. However, researchers found recently that the effect of turbulent characteristics of near surface wind in real atmospheric boundary layers on the sand transport rate was obvious. The turbulent characteristics would cause a significant discrepancy between field observation and simulation of sand transport rate. In this work, a field experiment in a real-time system was designed to synchronously measure physical quantities, such as fluctuating wind velocity in the near surface region, sand transport intensity, temperature, and humidity, with the frequency of 1 Hz, at two points on a homogeneous flat sand surface located in the Minqin area, which is between the edges of the Badain Jaran Desert and the Tengger Desert. The relationship between the saltation events and some physical properties, such as the fluctuating wind velocity, temperature, and humidity, was studied. On the basis of the field observation results, a numerical model was developed to simulate sand movement under the fluctuating wind. The overall features of the experimental measurements were reproduced by simulation.     

移动式无线激光通信基台结构与装调研究

针对近年各国对无线激光通信的应用越来越多,设计一款快速组网的无线激光通信基台。主要介绍了移动式无线激光通信基台的结构设计和5条光轴平行度的装调方法,满足系统通信的需要,同时对通信接收系统中直角棱镜的固定和调整机构做了介绍,并对5条光轴的平行度进行了简单的误差分析,可以满足系统的10平行度的要求。     

气体扩散方程解析解及在测定分子间势能的应用

设计了一新颖的分子动理论实验装置,根据求解在约束条件下的气体扩散方程的解析解和气体分子在升华时会对容器底部产生作用力的特点,设计了一种新颖简单的实验器材来测量分子间相互作用的势能,其实验曲线符合理论数据,误差分析后的补偿曲线所得结果可较为精确地与理论结果吻合。本实验常温下即可进行,且精度较高,适合快速材料性质测定及大学物理教学,以解决大学物理演示实验课关于学气体动理论的实验数量较少,且往往只涉及对热学微观过程的宏观模拟,而很少涉及气体动理论的实验,导致学生学习不够深入的问题。有利于学生对分子运动学问题的深入探索。     

面向学生能力培养的大学物理实验教学探索与实践

利用现有教学资源,面向全体大学物理实验选课学生进行了以学生为主体的实验教学探索。提出了学生能力培养的实验教学原则。从引导学生提出问题,改进实验处理和研究方法,开展课题研究性实验和学生参与科技制作四个方面介绍了大学物理实验教学的探索及实践。     

国外光电效应的模拟实验

介绍了美国高中物理教材中的光电效应的模拟实验,并从物理教学论的角度分析了实验设计的依据和实验要点.     

大学物理实验开放式教学的实现

提出了开展大学物理实验开放式教学的具体实现方法及步骤。     

炼油废水再生工艺技术

采用“悬浮载体生物深度处理、臭氧部分氧化及生物活性炭处理”等工序开发了一种新的炼油废水再生工艺技术，深度处理炼油废水。COD、BOD、NH3-N、油、硫化物、SS、细菌等主要污染物被有效去除，总出水清澈，无色无味，可满足工业用新鲜水、生活与办公、绿化等的水质要求，且处理费用低，运行稳定可靠。     

Regular Twists: Replicating Coulomb’s Wire-Torsion Experiments

I discuss our replication of the wire-torsion experiments that Charles Augustin Coulomb (1736–1806) reported in a session of the Paris Académie des Sciences in 1784. I first explain the nature and purpose of the replication method and then apply it to an analysis of Coulomb’s experiments. I conclude by placing Coulomb’s presentation of his memoir into its specific historical contest.     

A MINI MULTI-GAS DETECTION SYSTEM BASED ON INFRARED PRINCIPLE

To counter the problems of gas accidents in coal mines, family safety resulted from using gas, a new infrared detection system with integration and miniaturization has been developed. The infrared detection optics principle used in developing this system is mainly analyzed. The idea that multi gas detection is introduced and guided through analyzing single gas detection is got across. Through researching the design of cell structure, the cell with integration and miniaturization has been devised. The way of data transmission on Controller Area Network (CAN) bus is explained. By taking Single-Chip Microcomputer (SCM) as intelligence handling, the functional block diagram of gas detection system is designed with its hardware and software system analyzed and devised. This system designed has reached the technology requirement of lower power consumption, mini-volume, big measure range, and able to realize multi-gas detection.