从电磁学实验故障方析浅谈学生实验能力的培养

从电磁学实验故障方析浅谈学生实验能力的培养刘玉明（内蒙民族师院物理系通辽０２８０００）在电磁学实验中，往往由于仪器及学生操作等原因，会出现一些故障．故障是书本上没有的东西，但又是实验中经常遇到的问题，如不及时解决会影响学生的实验情绪，也使实验不能正常...     

加速器故障分析软件及其在CSNS应用

对加速器运行过程中出现的故障进行准确分析，可有效提升加速器的可靠性及运行效率。而对于一些快速故障过程，必须依赖故障发生时刻存储的高度时间相关和高分辨率的数据，才能进行准确分析。设计了一种用于加速器的故障分析软件，可用于对快速故障进行可靠分析。在中国散裂中子源加速器中进行了应用，该系统非常准确地分析了此前无法定位的大部分束流丢失过程。该故障分析具有一定的通用性，可应用到其它加速器装置。     

兆瓦级NBI加热系统弧流电源故障诊断方法探究

针对中国环流器2号A(HL-2A)装置弧流电源的特点，以及弧流电源故障诊断的条件与现状，提出了结合中性束注入(NBI)控制系统的相关功能模块与基于Matlab/Simulink仿真技术构建的故障字典，以实现弧流电源运行状态的在线监测及其故障模式的诊断。NBI控制系统在监测到弧流电源故障状态后，调用存储的弧流电源输出信号进行分析，提取信号的特征值，然后通过查找弧流电源故障字典以诊断出可能的故障模式。结合实验数据论证了该故障诊断法对弧流电源简单故障定位准确，对复杂故障能缩小定位范围，具有原理简单、可操作性强等优点。     

基于复小波包分形理论的爬壁机器人故障检测

通过研究爬壁式机器人的控制和运动特征，提出一种基于复小波包分形理论的故障检测方法．利用复小波包的平移不变性，将爬壁式机器人传感器输出信号分解成独立的频谱，并进行阀值处理和重构，从而有效去除高频噪音并提取故障的特征频率；依据信号分形维数的多尺度不变性，在嵌入维数空间，采用维数最大距离法，确定复小波包域故障信号的关联雏数．仿真实验表明，爬壁式机器人在各种异常工作模式下的故障信号关联维数能比较真实地反映其故障状态空间，同时也验证了故障信号的关联维数低于正常信号的关联维数作为故障发生与否的定量判据的正确性．     

一种混合型桥式高温超导限流器的研究

提出一种改进的桥式高温超导限流器拓扑结构。将不同高温超导体制成的限流电阻与限流电感同时串人桥式限流回路。正常状态下，限流电感与限流电阻均为超导态，限流器呈现低阻抗．故障状态下，限流电感保持超导态。利用电感抑制故障电流的快速增加；同时，由于故障电流超过限流电阻的临界电流值。超导体迅速失超导致线路阻抗突然增大。可以限制故障电流稳态值．本文进行了限流原理的理论分析，并进行了系统仿真．结果表明，该拓扑结构同时利用了超导体超导态的电感和失超后的电阻来限制故障电流，限流效果好，响应和复位速度快，是对桥式限流结构和混合型限流原理的有意义的探索．     

激光装置片状放大器组件的氙灯可靠性分析

 整理惯性约束聚变激光装置的运行记录和氙灯的故障数据，得到10种氙灯故障现象，并且归纳为3类,即触发故障、绝缘故障和氙灯爆炸，按故障发生时间可以分为“引发失效”的故障和“舍生取义”的故障。分析3类氙灯故障与片状放大器组件以及装置打靶成功率的逻辑关系，生成基于氙灯故障的装置打靶故障树，描述氙灯可靠性对于装置打靶成功的重要性。分析氙灯的生产工艺流程和工艺缺陷，生成氙灯的故障与工艺的鱼刺图，揭示氙灯故障的根源。     

基于LSSVM的电子装备故障预测研究

针对电子装备的故障信息不足,故障发生率高等特点,通过故障预测有效的监测设备故障状态以及发展趋势,实现对设备的事先维修,避免重大事故的发生,提高电子设备的安全性。对电子装备故障预测进行了分析,提出了一种基于最小二乘支持向量机（LSSVM）的故障预测方法。首先介绍了LSSVM故障预测算法的基本原理和预测流程;然后,对整个电子装备的故障预测研究可以从一个类似的模拟带通滤波器电路故障预测研究出发,将该元件容差设为不同范围来定义电路的不同故障状态,将LSSVM方法与最小二乘法、支持向量机法对电路的不同状态进行预测,可以得到不同状态的预测值,研究结果表明提出的方法能够实现模拟电路的缓变故障预测,且预测效果较好。     

世界首台超导限流-储能系统样机研制成功

从中国科学院电工研究所获悉，世界首台超导限流-储能系统样机近日在该所研制成功．试验表明，该样机可迅速有效地限制短路电流、进行功率补偿和平抑瞬态故障．据了解，该样机的研制是在科技部、中国科学院和国家自然科学基金委的支持下完成的．样机的研制从原理、设计、技术实施等方面都属世界首次．     

DV-4光谱仪光源系统故障诊断与维修

本文对DV－4光谱仪KH－3／5光源部分常见的故障进行分析，并且根据多年的实践总结出了处理故障的方法，使此类进口的精密仪器能够正常运行。     

DOS系统维护及故障排除

从计算机ＤＯＳ系统维护员的角度，阐述有关ＤＯＳ操作系统的维护及故障排除。     

Postgrowth residual stresses in polycrystalline zinc selenide

The residual stresses in samples of polycrystalline ZnSe are studied by measuring the photoelasticity in the visible part of the spectrum with transillumination parallel and perpendicular to the growth axis. The thermal and growth components of the birefringence, which exhibit different types of distributions among samples, are investigated. It is established that the thermal component has a nearly equilibrium distribution, while the growth component has an asymmetric distribution, which reflects individual features in the growth of each specific sample. Zh. Tekh. Fiz. 68, 85–90 (June 1998)     

Two component solution for an alternative order parameter in HTSC

In an early study the BCS wave function was generalized to include the motion of the center-of-mass of Cooper pairs. An alternative order parameter can be defined on the basis of this motion. In later work, when in copper oxides Bloch orbitals replaced free electrons, nodes were found in the vector space of the Fourier representation of the order parameter. Here that Fourier representation has suggested that the parameter consists of two components, a long wave lengths part which does not contain nodes, a short wave length part which does. The former component is real, and applies deep inside the superconductor, the latter, which is imaginary, in the boundary region. Further, the imaginary component has odd symmetry about the nodal axis. There results an addition of about 0.93π to the relative phase of two adjacent sides of a square superconductor cut along appropriate crystal axis, and embedded in a normal metal.     

机载位移传感器故障检测与信号重构

为了避免机载系统故障诊断与重构中单纯增加余度数目所带来的问题,针对电传飞控系统中应用较多的位移传感器,提出了一种基于特征的检测电路、检测方法以及信号重构方案。方案基于位移传感器工作时两次级线圈回路电压和值恒定的特征,实现了对初级、次级回路的一次断线检测,在检测到次级线圈一次断线时,又利用正常工作特征并根据另一次级线圈所获得的信息对断线信号进行重构。分析和测试表明,所提出的位移传感器故障检测以及重构算法仅需增加极少的硬件电路,且检测及重构方法实时性高,在不增加传感器余度数目的条件下,能大大提高系统的可靠性。     

Dynamics of cubic-tetragonal phase transition in KNbO<Subscript>3</Subscript> perovskite

The low-energy part of the vibration spectrum of KNbO₃ was studied by cold neutron inelastic scattering in the cubic phase. In addition to acoustic phonons, we observe strong diffuse scattering, which consists of two components. The first one is quasistatic and has a temperature-independent intensity. The second component appears as quasielastic scattering in the neutron spectrum, indicating a dynamic origin. From analysis of the inelastic data, we conclude that the quasielastic component and the acoustic phonon are mutually coupled. The susceptibility associated with the quasielastic component grows as the temperature approaches T _C .     

Forced nonlinear resonance in a system of coupled oscillators

We consider a resonantly perturbed system of coupled nonlinear oscillators with small dissipation and outer periodic perturbation. We show that for the large time t～?(-2) one component of the system is described for the most part by the inhomogeneous Mathieu equation while the other component represents pulsation of large amplitude. A Hamiltonian system is obtained which describes for the most part the behavior of the envelope in a special case. The analytic results agree with numerical simulations.     

Fermi arc formation by chiral spin textures in high-temperature superconductors

In angle-resolved photoemission spectroscopy pseudogap phenomenon in high-temperature superconductors is observed as Fermi arcs, or truncated Fermi surface. Here I argue that the hole induced chiral spin texture scenario naturally leads to Fermi arcs by including hole hopping processes. Disappearance of part of the Fermi surface is associated with the effect of the coherence factor. Suppressed spectral weight of the holes turns out to be an electron-like component which has weight near (π,0) only and has some charge instability.     

Identifying the incidence level of periodontal disease through hyperspectral imaging

This study proposes a method for staging periodontal disease through hyperspectral imaging technique. The study is composed of two parts. The first part shows the spectrum of gingival images that is simulated by hyperspectral imaging systematic analysis. The second part uses the principal component score chart for staging periodontal disease based on the obtained mean simulation spectrum. The experimental results show the staging results of periodontal disease through principal component score chart, allowing us to clearly identify the spectral features of normal gingiva and mild, moderate, and severe periodontitis. Our method can identify the stage of periodontal disease accurately and has a sensitivity and specificity of approximately 0.83 and 0.938, respectively.     

Reactor decay heat in 239Pu: solving the γ discrepancy in the 4-3000-s cooling period

The β feeding probability of (102,104,105,106,107)Tc, 105Mo, and 101Nb nuclei, which are important contributors to the decay heat in nuclear reactors, has been measured using the total absorption technique. We have coupled for the first time a total absorption spectrometer to a Penning trap in order to obtain sources of very high isobaric purity. Our results solve a significant part of a long-standing discrepancy in the γ component of the decay heat for 239Pu in the 4-3000 s range.     

密布式多输入多输出声呐阵列目标波达方向估计

针对低信噪比条件下多输入多输出声呐受对称噪声分量影响导致测向性能降低的情况,提出了一种基于协方差矩阵重构方法的波达方向估计算法。首先,将噪声场分为对称噪声和非对称噪声两部分,利用协方差矩阵虚部与对称信号无关的性质,去掉协方差矩阵的实部来降低对称噪声对目标波达方向估计精度的影响,采用降维转换方法和矩阵虚部置换原理重构协方差矩阵的实部,避免了双频谱的干扰。然后利用Toeplitz方法对重构的协方差矩阵进行解相干修正,通过奇异值分解获得噪声子空间,最后对目标的波达方向进行估计,可实现微弱信号的准确测向。理论分析和实验结果表明,该方法明显抑制了对称噪声,提高了目标的波达方向估计性能,具有运算速度快、自由度高和目标分辨力强的特点。      

Sound insulation of domestic roofing systems—Part 2

In the first part of this series of papers,² tests carried out on the ceiling component of a roofing system were described. In this second part, the experiments conducted on various types of roof component are outlined. The effect of coupling the ceiling and roof components to form the complete roofing system will be the central theme of the third and final part.