高速漏磁检测中速度效应的研究

介绍了漏磁检测中速度效应的基本原理,研究了高速检测下漏磁信号的变化规律,并对高速检测下的磁路设计和电路设计提出了改进.     

混凝土桥梁预应力钢绞线锈蚀漏磁检测实验研究

针对混凝土桥梁内部预应力钢绞线锈蚀无法提前检测的问题,结合漏磁检测的原理,设计制作了一套实验系统,能够检测到距离桥梁表面50mm深的钢绞线锈蚀缺陷。通过对桥梁模型上进行试验结果的对比分析,证明纵筋对检测结果没有影响,箍筋的存在产生的周期性信号对检测结果有较大影响。该实验系统具有较高的检测灵敏度,达到了检测实际应用要求,具有广泛的应用前景。     

检测输电线内部钢芯损伤的漏磁传感器设计

由于电流的集肤效应,涡流检测法主要适用于管、棒材表面裂纹及近表面裂纹的检测．高压输电线的内部钢芯只用于承受拉力和各种外界载荷,而基本无电流通过,所以检测钢芯缺陷的传感器最好采用漏磁检测法．文章介绍了这种漏磁传感器的设计方法．     

基于磁阻传感器的漏磁信号检测电路研究

针对铁磁性金属构件,阐述了基于应力测试的漏磁场检测原理,设计了基于HMC1021Z磁阻传感器的漏磁场检测电路,给出了各部分电路分析与设计要点,该电路具有高输入阻抗、地输出阻抗、低噪声等特点。实验测试表明,检测电路能够对铁磁性金属构件的漏磁场进行有效检测,为后续的信号特征提取与处理奠定了基础。     

漏磁检测技术在铁氧体缺陷检测中的应用

提出了一种基于漏磁检测技术的铁氧体缺陷无损检测方法。该方法通过对铁氧体进行局部磁化,在铁氧体缺陷周围产生漏磁场,磁敏传感器在经过缺陷周围时检测漏磁信号,进而识别缺陷特征。结合实验和仿真对所提出检测方法的可行性进行验证。结果表明,缺陷深度越大漏磁信号越强,同时磁场强度随着与缺陷中心距离的减小而逐渐增强,磁场强度在缺陷中心上方达到最大。研究结果为铁氧体表面缺陷无损检测提供一种新思路。     

LZW无损压缩算法在管道漏磁检测中的应用

漏磁无损检测是目前输油管道常用的安全检测方法,然而其检测数据庞大,必须要对数据进行压缩。介绍了一种基于字典存储技术的LZW(Lempel Ziv Welch)无损压缩算法,设计了一个基于FPGA和LZW压缩技术的管道漏磁数据无损压缩系统。通过调用FPGA仿真软件ModelSim对采集而来的漏磁数据进行压缩仿真,得到了较高的压缩效率,从而大大节省了存储器资源,降低了经济成本。     

基于漏磁可调机理的永磁同步电机弱磁性能研究

永磁同步电机性能优越被广泛应用在诸多行业。但是由于永磁同步电机采用永磁体励磁,无法调节励磁磁场,电机转速超过额定转速时必须进行弱磁控制以提升电机转速范围。针对永磁同步电机弱磁调速困难的问题提出一种基于漏磁可调机理的永磁同步电机方案。该方案通过导磁块在槽中的运动调节转子漏磁,从而调节气隙磁场强度。介绍基于漏磁可调机理的永磁同步电机的转子结构,阐述该电机的弱磁原理。运用有限元方法分析基于漏磁可调机理的永磁同步电机的空载磁场、额定负载运行时的电磁转矩和弱磁性能。研究电磁参数对弱磁调速性能产生的影响。仿真分析结果与理论分析结果相符合,验证基于漏磁可调机理的永磁同步电机实现宽弱磁调速范围的有效性和正确性。     

基于RBF神经网络滤波的噪声消除

RBF神经网络噪声抵消系统不需要关于输入信号和噪声的先验知识,非线性映射能力强。采用自适应噪声抵消基本原理,构造RBF神经网络自适应滤波器,然后针对该系统,建立Simulink仿真模型。仿真结果表明,该方法具有良好的噪声抑制能力。     

一种用于低频漏磁检测的交流恒流激励源

提出了一种基于电流闭环反馈控制和线性大功率放大器的恒流源设计方案。该系统采用增量型PID控制算法,以输出电流采样值为反馈量形成闭环反馈控制,通过动态调节幅度控制单元输出电压,实现对输出电流的闭环调节。选用线性大功率放大器,并采用双运放差分放大方式设计了功率放大单元,有效提升了输出电压幅度和线性度。采用最小二乘法修正了输出电流,恒流源输出精度获得了提升。利用所研制恒流源开展了低频漏磁检测实验研究。实验结果表明:该恒流源输出稳定,调节精度高,线性度好,以其作为低频交流漏磁检测激励源,有效避免了因激励信号频率、提离值发生变化和线圈自身发热等因素所造成的激励电流改变,保证了激励磁场的稳定,可有效提高低频漏磁检测精度和稳定性。     

基于混合注意力机制的管道漏磁缺陷分类实验

该文将管道漏磁缺陷分类任务设计成应用型教学实验。该实验使用迁移学习的方法,调用预训练模型ResNet50,并插入主流的注意力机制（SE、CA、ECA、CBAM）进行对比分析。同时,利用Grad-CAM++可解释算法对模型内部的识别逻辑进行可视化,以便帮助学生更好地理解模型。实验结果显示,插入注意力机制的最优模型准确率达99.7%,能够有效识别管道中的正常情况和分类缺陷情况。该实验依托高性能计算机硬件和最新的Pytorch2.0软件包搭建了深度学习平台,有助于培养学生的创新意识和科研能力,也是对多学科交叉融合人才培养模式的探索和实践。     

BP神经网络在管道缺陷定量识别中的应用

介绍了漏磁检测的基本原理,分析了管道缺陷的漏磁信号与缺陷几何参数的关系.应用BP神经网络进行了管道缺陷参数的定量识别,识别结果的误差小于10%,完全满足实际检测的要求.     

噪声主动控制的进展及发展趋势

对噪声主动控制技术领域的进展及发展趋势进行综述.包括消声原理、消声器结构和算法等方面的研究成果,分析该技术存在的缺陷,对今后的主要发展方向作出预测.     

无人直升机旋翼转速控制器设计

针对无人机的特殊性以及对电机动态性能的要求,设计了一种以ARM芯片LPC2148为核心的旋翼转速控制器。首先分析了直升机的飞行特点以及原旋翼转速控制器的不足,设计基于EKF和矢量控制的新旋翼转速控制器,并对扩展卡尔曼滤波法和矢量控制的模块进行说明,且给出了MATLAB仿真结果,验证了控制系统的正确性。     

VCA Direct-Drive High Speed and Precision XY Table

In order to compensate for the limitation of conventional XY table used in semiconductor integrated circuits(IC) packaging and improve its speed and accuracy, a voice coil actuator (VCA) direct-drive high-speed and precision positioning XY table used in wire bonder was proposed. Also, a novel flexible decoupling mechanism was used in the positioning table, and the small moving mass enabled the positioning table to move at high speed and precision. XY table deformation interference caused by assembly error and instant interference generated by dynamic load moving with high speed and acceleration can be eliminated through the flexible decoupling mechanism. Considering the positioning table as lumped mass spring system,the dynamic equations of the mechanical system and the VCA were built according to the Newton mechanics principle and electromagnetic theory. Then the electromechanical coupling control model of the system was created through Laplace transform. Based on displacement PID controller, the loop-locked controlling algorithm of the positioning system was investigated. The dynamic control algorithm effectively improved the system dynamic performance. The precision test of the prototype machine was carried out, and the results validated the correctness of the model and the theory. Compared with traditional XY table, the table has higher speed, acceleration and positioning accuracy.     

Modern foreign language education for learners with additional support needs in Scotland

The face of Modern Foreign Language education (MFL) in Scotland is changing. A major policy shift in Scottish education in 2012 set out the aspiration that all students up to the end of third level education in Scottish schools would have the opportunity to learn not one but two languages, in addition to their mother tongue. Over the last 20 years, there has been, concurrently, an undertaking by the Scottish government, in a series of policy documents, committing to provision that will ensure that students with additional support needs (ASN) receive equality of access to a broad and balanced education. This paper draws upon policy documents and published research in the area to review the extent to which the vision of language learning of all has been made available to students with ASN and the documented benefits associated with MFL education for those with ASN. Drawing upon case studies of inclusive MFL pedagogies, it identifies successful strategies that can be deployed by teachers. It then considers some of the mechanisms by which the current gaps in provision have arisen and proposes possible remedial steps, drawing on both an analysis of policy and case studies of effective practice.     

Low-cost fault tolerance in evolvable multiprocessor systems: a graceful degradation approach

The evolvable multiprocessor （EvoMP）, as a novel multiprocessor system-on-chip （MPSoC） machine with evolvable task decomposition and scheduling, claims a major feature of low-cost and efficient fault tolerance. Non-centralized control and adaptive distribution of the program among the available processors are two major capabilities of this platform, which remarkably help to achieve an efficient fault tolerance scheme. This letter presents the operational as well as architectural details of this fault tolerance scheme. In this method, when a processor becomes faulty, it will be eliminated of contribution in program execution in remaining run-time. This method also utilizes dynamic rescheduling capability of the system to achieve the maximum possible efficiency after processor reduction. The results confirm the efficiency and remarkable advantages of the proposed approach over common redundancy based techniques in similar systems.     

Dynamics analysis of vibration process in Particle Impact Noise Detection

Particle Impact Noise Detection (PIND) test is a reliability screening technique for hermetic device that is prescribed by MIL-PRF-39016E. Some test conditions are specified, although MIL-PRF-39016E did not specify how to obtain these condi- tions. This paper establishes the dynamics model of vibration process based on first order mass-spring system. The corresponding Simulink model is also established to simulate vibration process in optional input excitations. The response equations are derived in sinusoidal excitations and the required electromagnetic force waves are computed in order to obtain a given vibration and shock accelerations. Last, some simulation results are given.     

Science Letters: Low-cost fault tolerance in evolvable multiprocessor systems: a graceful degradation approach

The evolvable multiprocessor (EvoMP), as a novel multiprocessor system-on-chip (MPSoC) machine with evolvable task decomposition and scheduling, claims a major feature of low-cost and efficient fault tolerance. Non-centralized control and adaptive distribution of the program among the available processors are two major capabilities of this platform, which remarkably help to achieve an efficient fault tolerance scheme. This letter presents the operational as well as architectural details of this fault tolerance scheme. In this method, when a processor becomes faulty, it will be eliminated of contribution in program execution in remaining run-time. This method also utilizes dynamic rescheduling capability of the system to achieve the maximum possible efficiency after processor reduction. The results confirm the efficiency and remarkable advantages of the proposed approach over common redundancy based techniques in similar systems.