As a basic electrical component,thermistor is widely used in electrical integrated systems.Experience shows that its electrical performance parameters are easily affected by climatic tests.The effects of five typical climatic tests on the electrical performance parameters of thermistors are studied in this paper.The test items include high temperature test,low temperature test,rapid temperature change test,temperature cycle test and salt spray test.At the same time,the effects of two typical test sequences on its electrical parameters were studied.It is found that the temperature cycle has little influence on the nominal zero power of thermistor,and the deviation is less than 5%.High temperature and low temperature test have some influence on it,the deviation is less than 10%;Salt spray and rapid temperature change test have great influence on it,the deviation is greater than 20%.In addition,the harshness of test sequence 2 is much higher than that of sequence 1,resulting in greater damage to the sample.The salt spray test may affect the internal contamination level of the sample,and the rapid temperature change test has a greater severity and should usually be carried out after the completion of other environmental tests.The research of this paper will provide some reference for the revision of standards and the formulation of test engineers'schemes.
The dynamic stiffness and impact stiffness of isolators are the core technical indicators for the performance evaluation of isolators.Accurate assessment is necessary to meet the needs of different usage environments.The main methods for testing dynamic stiffness include the ellipse method,vibration excitation method,and self-excited oscillation method.The main techniques for testing impact stiffness are the drop method and the drop hammer method.Choosing the appropriate testing method based on the characteristics of the test piece can greatly improve efficiency.This paper employs the vibration excitation method to conduct dynamic stiffness simulation and experimental analysis on the spring oscillator isolator model,and uses the drop method for impact stiffness simulation and experimental analysis of the same model.Based on a comparison of simulation analysis and experimental analysis,the effectiveness of the tests was clarified.Moreover,the advantages and disadvantages of various testing methods for dynamic and impact stiffness were sorted out based on the relevant experimental data,to serve as a reference for related testing technicians.
电力系统中窃电行为对线损计算和电网经济运行造成不利影响,严重影响电力市场的经济秩序.基于此,本文提出了一种基于集成机器学习的电力系统窃电辨别方法,以快速准确的辨别窃电行为.首先,该方法建立了基于改进神经网络的电力系统窃电行为特征提取模型,利用实测数据与神经网络全变量重构值进行比较,以获取用电数据的抽象行为特征;然后,利用提取出的窃电行为特征,采用集成机器学习方法进一步推导出电力系统窃电行为辨别方法;最后,基于实际数据集,验证了所提算法具有较高的检测灵敏度和分类精度.
介绍了汽车用钢板常见的盐雾试验种类及原理,以G公司过往盐雾试验结果为例,分析阐述了镀锌板和冷轧板在不同盐雾环境下的腐蚀行为差异,并对当前腐蚀评价方法存在的课题进行探讨和优化.为了提高盐雾试验可靠性和稳定性,提出相关优化方案:①镀锌板腐蚀验证建议采用CCT循环盐雾试验,冷轧板腐蚀验证建议以SST中性盐雾试验为主,CCT循环盐雾试验为辅进行开展;②盐雾试验表面划线建议采用标准刀具+划线器的方式进行划线.
放电容量是评估电动自行车用锂电池电性能的重要指标.本文根据相关国家标准对电动自行车用锂电池放电容量进行测试,分析检测过程中可能因设备、电流、时间等因素产生的测量不确定度,并建立测量不确定度与实际应用相结合的符合性判定模型,分析不确定度评定对电动自行车锂电池放电容量符合性判定的影响.更好地保障检测结果的可靠性、准确性.
