- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Disturbances Generated by Lighting Systems with LED Lamps and the Reduction in Their Impacts
摘要： The paper deals with electromagnetic disturbances in the form of current higher harmonics, which are generated by LED lighting elements. It presents the problems related to the formation and impact of higher harmonics in the electrical systems of commercial facilities. The results of tests and analyses of current distortions for two di?erent LED lamps are included, and these are in reference to the parameters set out in the normal applicable standards. A system was then proposed to improve the quality of energy in the mains of commercial facilities in the form of a two-stage power supply. Tests of the systems with the aforementioned LED lamps were conducted and commented upon after introduction of the two-stage power supply. The ?nal part of the paper contains a summary of the obtained test results.
关键词： electromagnetic compatibility,total harmonic distortion (THD),LED lamp,two-stage power supply,current and voltage distortion,lighting system,power factor correction (PFC),higher harmonics
更新于2025-09-16 10:30:52
-
Unlocking higher harmonics in atomic force microscopy with gentle interactions
摘要： In dynamic atomic force microscopy, nanoscale properties are encoded in the higher harmonics. Nevertheless, when gentle interactions and minimal invasiveness are required, these harmonics are typically undetectable. Here, we propose to externally drive an arbitrary number of exact higher harmonics above the noise level. In this way, multiple contrast channels that are sensitive to compositional variations are made accessible. Numerical integration of the equation of motion shows that the external introduction of exact harmonic frequencies does not compromise the fundamental frequency. Thermal fluctuations are also considered within the detection bandwidth of interest and discussed in terms of higher-harmonic phase contrast in the presence and absence of an external excitation of higher harmonics. Higher harmonic phase shifts further provide the means to directly decouple the true topography from that induced by compositional heterogeneity.
关键词： composition,phase,heterogeneity,chemistry,higher harmonics,atomic force microscopy
更新于2025-09-09 09:28:46