基于网络的温度传感器动态补偿实验

提出了通过网络技术实现多用户同时进行实验教学的方案,改进了经典的温度传感器动态补偿实验,解决了学生数量日益增加和硬件资源相对紧张的矛盾,同时在方案中增加了学生自主补偿设计功能,充分调动了学生自主实验设计的兴趣,获得了满意的教学实践效果。     

Microstructural evolvement of wrought magnesium alloy sheet during heat treatment

1. Introduction Magnesium is the lightest metal structural material with low density and many strong points. Compared with its cast counterpart, the wrought magnesium alloy has found more promising perspective of application in many fields such as automobiles, aeronautics and electronic communication [1]. The application of magnesium has been greatly constrained by its low ductility at room temperature due to its hexagonal closest packing (hcp) crystal structure (the regular cast magnesium all…     

集成开关型霍耳传感器在复摆实验中的应用

集成开关型霍耳传感器是一种基于霍耳效应的磁敏开关.把先进的集成开关型霍耳传感器应用于复摆实验中,研究复摆周期的变化规律,测量精度高,同时提高了经典物理实验的现代化水平.     

永磁同步电机无测速传感器控制系统设计

针对工业生产中永磁同步电机控制系统需降低生产成本、节约能源的实际需求,设计了永磁同步电机无测速传感器控制系统。选用矢量控制,保证电流与转矩成正比关系变化。利用Sigmoid函数代替切换函数,减小抖振。通过对不同负载情况下的仿真,验证了电机转速能较好地跟踪转速的给定值,滑模观测器估算精度较高,系统具有鲁棒性。     

Volumetric fraction measurement in oil-water-gas multiphase flow with dual energy gamma-ray system

INTRODUCTION Oil-water-gas multiphase mixed transport in oil pipe is extensively used in ocean oil industries. How to measure the volumetric fractions of oil-water-gas multiphase flow is an important subject of study in the oil industry. Related research work was started in the 1980s. The measurement of component ratios in multiphase flows using γ-ray attenuation was first suggested by Abouelwafa and Kendall (1980), and the technique has been used in many current com- mercial multiphase…     

What leads people to keep on e-learning? An empirical analysis of users' experiences and their effects on continuance intention

User retention is a major goal for higher education institutions running their teaching and learning programmes online. This is the first investigation into how the senses of presence and flow, together with perceptions about two central elements of the virtual education environment (didactic resource quality and instructor attitude), facilitate the user's intention to continue e-learning. We use data collected from a large sample survey of current users in a pure e-learning environment along with objective data about their performance. The results provide support to the theoretical model. The paper further offers practical suggestions for institutions and instructors who aim to provide effective e-learning experiences.     

用于确定疲劳载荷谱的共轴直升机气动力参数数值模拟

本文探索了共轴直升机气动力参数估算技术,用以确定其疲劳载荷谱。首先给出了气动力计算的主控方程和数值方法,然后,分别建立了共轴直升机机身与旋翼的三维层流和湍流流场模拟的物理模型和计算网格模型,采用计算流体力学(CFD)方法,进行了共轴直升机机身与旋翼的层流和湍流流场数值模拟,估算了其气动力参数曲线,并对计算结果进行了分析对比,以检验建模技术的有效性,分析结果表明:该项技术实用可行,能得到一些与工程实际吻合的现象和结论。     

"混合法测定金属比热容"实验中温度测量装置的改进

对"混合法测定金属比热容"实验中传统的温度测量装置进行了改进,引入了多种温度测量的装置,提高了实验效果。     

A model based algorithm for fast DPIV computing

Traditional DPIV (Digital Particle Image Velocimetry) methods are mostly based on area-correlation (Willert, C. E., 1991). Though proven to be very time-consuming and very much error prone, they are widely adopted because of they are conceptually simple and easily implemented, and also because there are few alternatives. This paper proposes a non-correlation, conceptually new, fast and efficient approach for DPIV, which takes the nature of flow into consideration. An Incompressible Affined Flow Model (IAFM) is introduced to describe a flow that incorporates rational restraints into the computation. This IAFM, combined with a modified optical flow method-named Total Optical Flow Computation (TOFC), provides a linear system solution to DPIV. Experimental results on real images showed our method to be a very promising approach for DPIV.     

WSNs中基于节点信任度的机会路由算法

针对机会路由的候选转发集中存在恶意节点导致网络性能下降问题,提出一种计算节点信任度的评估模型。使用贝叶斯公式计算节点的直接信任度,根据节点的代数连通度得到间接信任度,利用信息熵的概念得到综合信任度。为高效辨别出候选转发集中的恶意节点,预先设定信任度阈值[β]。提出一种基于节点信任度的机会路由算法TBOR。TBOR利用信任模型初始化候选集中每个节点的综合信任度,再利用信任度阈值判断潜在的恶意节点,并将信任度大于信任度阈值的节点添加到候选转发集。实验结果表明,TBOR能高效识别并剔除候选转发集中的恶意节点,具有较高的检测率,保证了数据可靠传输。