磁粉检测在用压力容器时磁粉材料的选择

在用压力容器磁粉检测能否检出缺陷取决于磁化方法、磁化效果、磁粉性能、检测环境和检测者的素质,磁粉材料选择是制定检测工艺中的重要内容之一。本文简要介绍了磁粉材料的特性、各种磁悬液的配方和配制方法;如何根据被检压力容器特点正确选用磁粉材料,使磁粉检测取得预定效果     

带涂层压力容器的磁粉检测

大型石化厂压力容器设备,大多数采用的材料是铁磁性材料,所以在定期检验采用的几种无损检测方法中,运用最多的是磁粉检测。设备运行产生的缺陷多数首先在表面、近表面反映出来,而磁粉检测方法的优势恰恰是容易发现这些缺陷,且操作简单、效率高、成本低,显示直观,因此该方法就成为容器定检中首选的检测方法。磁粉检测的准确性直接影响容器定检的可靠性和设备使用的安全性。     

在用蒸压釜磁粉检测中应注意的几个问题

针对双开门结构在用蒸压釜两次全面检验。总结了在用蒸压釜运行特点和在检测中应注意的问题．分述如下：     

一种新型的互感器极性数字化检测系统

基于传统互感器极性手动直流检测原理,设计了一种新型的互感器极性数字化检测系统。该系统首先对互感器一次线圈施加脉冲电压,利用检测电路对脉冲电压施加过程中二次回路信号进行数字化检测,通过对脉冲电压施加过程中二次回路信号的变化规律分析,实现对互感器极性的自动判断。整个系统相对于传统手动直流检测方法具有检测方便、检测效率高等特点。     

一种新型空燃比检测方法的初步研究

用离子电流法在一种新型直管道燃烧器中,对预混天然气空气混合气进行燃烧基础特性的测试。通过控制预混压力和空燃比两个参数变化,消除了由于发动机循环变动对燃烧状态和离子电流强度的不稳定影响。分析了空燃比、预混压力变化与离子电流信号的关系,试验研究表明离子电流法可用来检测空燃比,为在发动机上的应用提供了基础性研究。     

一种新型自焙电极压放量检测方法

在对比几种检测方法的基础上,介绍了一种新型的电极压放量检测方法。     

异形工件专用荧光磁粉探伤机的研制使用

众所周知,磁粉探伤作为铁磁性材料表面缺陷最有力的检测手段在检测工作中得到了十分广泛的应用。在锅炉、压力容器、压力管道及石化管件及一些大型构件的局部检测中一般采用磁轭法或旋转磁场法探伤,但对一些形状复杂或工件有一定批量的情况这种方法就显得效率不高和灵敏度不够,存在局部漏检现象。在无损检测工作中,经常会遇到一些特殊工件的无损探伤难以有效进行。比如对石化管件（如三通、四通等）、     

一种新型牵引电动机自动保护装置

简要阐述了一种新型直流牵引电动机自动保护装置,该装置实现了DF4、DF8、DF8B及DF11型机车牵引电动机过流故障或接地故障的自动保护功能,同时不影响其他电机正常运行.     

TOFD检测技术应用实例探讨

随着TOFD检测技术在我国的研究和试验应用,该技术已应用到锅炉压力容器制造行业,但大部分探伤人员对该技术还不熟悉。本文先简要介绍了一下TOFD检测技术,然后就两个TOFD检测工作实例进行了探讨。结果表明,TOFD检测技术是一项可靠且环保的无损检测技术。     

基于超松弛法的行程传感液压缸磁路结构的研究

针对一种新型的行程传感液压缸，提出了测量所用的磁路结构。并用超松弛法对这种磁路结构进行了磁场分析，确定了各结构参数间的关系式；然后选取二组结构参数进行了实验验证。实验结果表明：理论分析的结果是正确的。     

ITER高功率磁场抗扰度测试系统研究

目的  为了保证设备的安全稳定运行,受国际热核实验堆（ITER）组织监管的电力电子设备必须通过相关的磁场抗扰度测试。 方法  以ITER要求为基准,定义了所需测试系统的参数要求,选择方形螺线管线圈和方形三线圈作为研究对象,通过数值计算方法计算出最优性能的结构参数,并使用有限元的方法验证计算的正确性。 结果  对比两种线圈型式,选择功耗较小的螺线管作为最终的结构。然后以此参数为基准,分析了直流暂态的功率拓扑,计算了相关参数,确定了最终电源所需要的性能数据。 结论  研究为ITER高功率磁场抗扰度测试系统的感应线圈及其电源的设计提供了详细的计算过程和设计参考。     

建筑外墙传热系数检测技术的研究

阐述了目前建筑外墙围护结构传热系数检测方法存在的一些问题,分析了含湿量对墙体传热系数的影响,针对存在的问题结合夏热冬暖地区气候条件,提出了一种可操作的科学的试验室检测方法,采用调节室调节的方式以快速达到检测的要求,大大方便了节能验收和工程质量控制。     

基于超松弛法的行程传感液压缸磁路结构的研究

针对一种新型的行程传感液压缸,提出了测量所用的磁路结构。并且超松弛法对这种磁路结构进行了磁场分析。确定了各结构参数间的关系式;然后选取二组结构参数进行了实验验证。实验结果表明：理论分析的结果是正确的。图12参4     

燃煤可吸入颗粒物在高梯度磁场中的捕集试验研究

针对3种不同磁特性的燃煤可吸入颗粒物(PM10),利用高梯度磁场试验装置进行了颗粒捕集的试验研究,用电气低压冲击器(ELPI)实时测量了颗粒浓度的变化.结果表明:开启磁场后燃煤可吸入颗粒物捕集效率的变化可分为缓慢提高、快速提高和稳定3个阶段;饱和磁矩较大的样品,其捕集效率较高;增加磁场强度和磁介质的填充率可以提高燃煤可吸入颗粒物的捕集效率;而气体流速的增大则会导致颗粒捕集效率降低.试验表明,高梯度磁场捕集燃煤可吸入颗粒物是一种新型有效的方法.     

A new flame sheet model to reflect the influence of the oxidation of CO on the combustion of a carbon particle

A model with a moving flame front is proposed for the combustion of a carbon particle, taking into account the effect of CO oxidizing in the boundary layer around the particle. Using this model, the continuous transition of the effective combustion product from CO₂ under the ignition condition to CO under the condition of diffusion control has been successfully realized. Good agreement was obtained with the experimental measurements of Young and Niksa; such agreement could not be obtained using the customary single-film model.     

Development of a mesoscopic particle model for synthesis of uranium-ceramic nuclear fuel

A novel technique has been developed to fabricate uranium-ceramic nuclear fuel using the depleted uranium (DU), U₃O₈ powder, and allylhydridopolycarbosilane (AHPCS) polymer precursor. This process involves a continuous change of the composition, porosity, and material properties. To fabricate nuclear fuel with a uniform structure/volume ratio, it is important to understand the transport phenomena during high temperature processing and at different length scales. In our prior work, a system-level model based on the reactive porous medium theory was developed to account for pyrolysis process during the uranium-ceramic fuel fabrication. In this paper, a mesoscopic model based on the smoothed particle hydrodynamics (SPH) is developed to simulate the synthesis of filler U₃O₈ particles and SiC matrix. The system-level model provides the necessary thermal boundary conditions for the mesoscopic simulation. The evolution of the particle concentration and the structure as well as the composition of the composite produced is investigated. Since the process heat flux plays an important role in the material quality and uniformity, the effect of the heating rate, filler particle size and distribution on the uniformity and the structure of the final product are investigated. The uncertainty issue is also discussed.     

基于改进粒子群算法的风力机选型应用研究

风力机的选型是风电场建设的重要内容,它对风电场建设造价、投产后的发电量以及运行维护成本等有直接影响。文章在给定风资源的情况下,综合考虑风电场的容量系数和实际发电量,以风力机性能指数作为选型的依据,针对采用常规方法进行风力机参数线性化求解的缺陷,采用智能化的改进粒子群算法对风力机参数进行寻优。与常规计算方法相比,该方法寻得的风力机性能指数更优。结合具体实例计算候选机型的风速加权标准差,选出最优风力机。该研究结果为风电场的风力机选型提供了一种有效可行的方法,具有一定的应用参考价值。     

Comparison of single particle and equivalent circuit analog models for a lithium-ion cell

The physics-based single particle (SP) model was compared to the semi-empirical equivalent circuit analog (ECA) model to predict the cell voltage under constant current charge and discharge for different sets of Li-ion cell data. The parameters of the models were estimated for each set of data using nonlinear least squares regression. In order to enhance the probability of finding the global optima, a combination of the trust region method with a genetic algorithm was applied to minimize the objective function (the sum of squared residuals). Several statistical quantities such as sum of the squared errors, adjusted R², root mean squared error, confidence intervals of the parameters, and prediction bounds were included to compare the models. A significance test (t test) on the parameters and the analysis of the variances (F and χ² tests) were also performed to discriminate between the goodness of the fit obtained from the two models. The statistical results indicate that the SP model superiorly predicts all sets of data compared to the ECA model, while the computation times of both models are on the same order of magnitude.     

Effect of inert particle concentration on the operation of a microbial fuel cell

Considering the promising application of microbial fuel cells (MFCs) in the wastewater treatment, the inherent solid particles in the wastewater may affect the MFC performance. In this paper, the effect of inert particle concentration on the operation of MFCs is investigated by adding silicon dioxide (SiO₂) particles into the anolyte. The results show that the existing SiO₂ particles in the anolyte result in a decreased active biomass and a reduced electrochemical activity of the biofilm. The anode ohmic resistance is almost the same for MFCs with various SiO₂ particle concentrations in the anolyte, while an increase in the charge transfer resistance is observed. A small amount of inert particles have little influence on the MFC. However, when the MFC is operated with the anolyte containing more than 500 mg L⁻¹ SiO₂ particles, the performance decreases significantly due to the low electrochemical activity and high internal resistance of the anode.