谐波的产生、危害及抑制

对变压器、整流设备等谐波的产生及其危害作了较全面的分析，并对其抑制提出了具体可行的办法。同时给出了应用实例，应用结果表明，三的倍数次谐波可得到有效抑制。     

整流装置高次谐波污染的危害及抑制措施

介绍了整流装置高次谐波污染的产生原因极其对电网和其它用电设备的危害性，并通过理论和实例分析和介绍了对高次谐波污染的抑制措施，希望对从事电气技术工作的同行有一定的参考价值。     

铜电解整流器谐波的抑制

电解整流器等非线性电力设备接在企业配电系统和电网上运行时,将向配电系统及电网注入谐波电流,并产生不良影响及危害。从自身运行的安全和对电网限制谐波要求两方面考虑,都必须对整流设备及其它非线性用电负荷设备产生的过量谐波进行有效的抑制。     

采用节电滤波器 实现电机节能降耗

本文就电网存在的各种谐波对电网及电气设备带来的危害进行分析,从中找出捕捉、抑制、过滤电网中的杂散谐波的有效办法。从而达到清除污染、节约电能、保护设备之功能,并对电机采用节电滤波器抑制谐波、瞬流,实现节能降耗进行了探讨。     

谐波生成原理及治理方法

现行用电设备中非线性元件大量使用,造成电网中大量谐波的产生,对电网造成严重污染,采用单调滤波装置对各次谐波的吸收,抑制谐波电流的放大,对电网起到一定的净化作用,对电网的安全运行提供保障。     

大型变频调速装置的高次谐波电流对电网的影响及其抑制

本文简述了大型变频调速装置的高次谐波电流对电网的影响及其抑制方法，并介绍了采用谐波滤波器抑制高次谐波电流的实例及其抑制效果。     

谐波对电网阻抗的影响及抑制方法

高次谐波对电网质量的影响及如何抑制谐波是目前急需解决的重要课题。从理论上分析了谐波对变压器阻抗，输电线路阻抗，负荷阻抗的影响，同时提出了几种抑制谐波的方法。     

变频器谐波的产生与抑制

本文从变频器产生谐波干扰的途径入手，介绍变频器的谐波产生机理，减少变频器谐波对其它设备的影响，初步提出减少或削弱变频器谐波及电磁辐射对设备干扰的方法。     

有源电力滤波器在污水处理厂中的应用

为减少污水处理设备产生的各次谐波,通过确定主要谐波源,检测和计算谐波分量,采用有源电力滤波器进行谐波治理,大幅降低了电力系统中的三相电流畸变率,提高了电能质量;抑制了谐波分量,减少了由谐波引起的电气设备故障,保证了电力系统的正常运行。     

轧钢生产线变频调速系统的干扰分析与抑制

分析了现场供电和其他用电设备对变频器的干扰和变频器运行时产生的高次谐波对电网和周围设备的干扰,结合某轧钢生产线的实例,具体阐述了几种抑制变频器产生的干扰的思路和方法.     

Tissue harmonic imaging: why does it work?

The recent utilization of harmonic frequencies in the imaging of both tissue and contrast agents has dramatically improved echocardiographic image quality. In contrast harmonics, the harmonic frequency energy is generated on reflection from the microbubble contrast agent. In tissue harmonics, the harmonic frequency energy is generated gradually as the ultrasonic wave propagates through the tissue. Critical to the utility of tissue-generated harmonic frequencies is their origin beyond the chest wall and their nonlinear relation to the fundamental frequency energy strength. These two characteristics of tissue-generated harmonics ensure that the echoes most likely to produce artifact are least likely to produce harmonic waves. Armed with an understanding of how these images are produced and with data emerging as to their clinical utility, we anticipate that harmonic imaging will become the standard for assessing regional and global left ventricular function in technically difficult studies.     

印度BSP钢包精炼炉滤波器特性及配置选择

根据多年来实际工程对钢包精炼炉谐波特性的分析,其产生的谐波电流除整数次谐波较大外,同时含有0.1~30 Hz的低频分量(次谐波)和非基波(50 Hz)频率整数倍的谐波分量(间谐波),仅配置一般的单调谐滤波器不能起到很好的滤波作用,反而会造成某些谐波放大。设置一个C型阻尼滤波器支路,可以拓宽频带,增加阻尼和减少电阻基波功率损耗,实际应用效果明显。     

冶金企业电力系统谐波分析及治理

对谐波源及谐波产生进行了分析,有针对性地装设滤波补偿装置,对电网谐波进行综合治理,以确保供电系统电能质量。     

谐波对硅钢片磁性能的影响

针对电机实际运行过程中存在的谐波环境,对不同谐波条件下无取向硅钢片的磁性能进行了研究。采用w(Si)为3%的高牌号无取向硅钢,在磁性测量设备上设置不同次数的谐波,对其磁性能进行了测试。试验结果表明,相对于正弦波条件下的磁性能,3次谐波能造成铁损明显上升;随着谐波次数的增加,谐波引起的铁损会降低并逐渐趋向稳定,但单次谐波对磁感无明显影响;复合多次谐波增加铁损最为显著,并且降低低场下的磁感。     

Timbre control in zebra finch (Taeniopygia guttata) song syllables.

Zebra finch (Taeniopygia guttata) song syllables often include harmonically related frequency components. These harmonics may be suppressed, and this differential emphasis varies between the syllables in a song and between individual birds' songs. These patterns of harmonic suppression are timbre. Individual syllables' patterns of harmonic suppression are constant within adult males' songs. Young males that imitate the songs of older males also imitate their patterns of harmonic suppression. Syringeal denervation distorts these patterns, which suggests that they are produced through active control of the vocal organ. The selective suppression and emphasis of some harmonics creates a great number of possible timbre variants for any one syllable. These add signal diversity to the limited array of frequency modulations and range of fundamental frequencies found in zebra finch song. Analyses of bird song that disregard timbre may overlook a feature that is important in vocal communication. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Harmonic imaging

Microbubbles undergoing resonant oscillation in a diagnostic ultrasound field can be induced to exhibit nonlinear motion. The ultrasound signals emitted by such microbubbles contain strong harmonics at twice the frequency of the transmitted ultrasound beam. Second harmonic imaging improves tissue-agent contrast. The usefulness of second harmonic imaging was evaluated in vivo experiments. The hepatic parenchyma was clearly enhanced in dogs. Second harmonic imaging can be expected to expand the capabilities of diagnostic ultrasound systems in visualizing tissue perfusion.     

直流电弧炉,直流钢包精炼炉的谐波分析与抑制

定性分析了整流装置是主要的谐波源以及谐波的危害，指出了抑制谐波的各种措施、并以实例加以说明。     

Timbre discrimination in Zebra finch (Taeniopygia guttata) song syllables.

Zebra finch songs include syllables of a fundamental frequency and harmonics. Individual harmonics in 1 syllable can be more or less emphasized. The functional role of this variability is unknown. These experiments provide evidence of how the phenomenon is perceived. We trained 12 male and female zebra finches on a go-no-go operant procedure to discriminate between 2 song syllables that varied only in the absence of the 2nd or 5th harmonic. Training involved many thousands of trials. Both sexes used the presence or absence of the 2nd harmonic as the sole discriminative cue. Females had more difficulty learning to perform the task when the presence of the 2nd harmonic was the go stimulus, which indicates that their use of the information was biased by stimulus-response contingencies. The results are discussed in terms of broad strategy to understand how animals perceive sounds used in communication. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Profiling the perceptual suppression of partials in periodic complex tones: further evidence for a harmonic template

The basis for the perceptual cohesion of periodic complex tones was investigated. In experiment 1, 2-4 consecutive components (harmonics 6 and above) were removed from a 14-harmonic complex and replaced with a sinusoidal "probe," located at one of a set of regularly spaced positions spanning the gap. On each trial, subjects heard a complex tone followed by an adjustable pure tone in a continuous loop. Subjects were better able to match the pure tone to the probe when the probe did not coincide with a harmonic position. Minima in "hit rate" were more pronounced when harmonic probes were in positions adjacent to other harmonics than when they were not. These findings suggest that the pitch of each in-tune partial was actively suppressed by a template whose influence attenuated with distance from regions of consecutive harmonics. In experiment 2, the partials on either side of the spectral gap were harmonics of different fundamental frequencies. Hit-rate minima corresponding to both fundamentals were found, indicating an upward and downward spread of suppression, and also demonstrating the concurrent operation of two templates. The results confirm recent findings in support of template models, and are consistent with the idea that partial-pitch suppression underpins harmonic fusion.     

Strategies for harmonic structure discrimination by zebra finches

We trained zebra finches on a go/no-go operant conditioning procedure to discriminate between two harmonic structures that differed only by the presence or absence of the second harmonic. Test sessions revealed that the birds responded to probe stimuli based on the presence or absence of the second harmonic regardless of the other frequency components. Some of the birds also tended to use the fundamental frequency as a discriminative cue when the number of harmonics was few. These results indicate that birds use multiple strategies for this type of harmonic structure discrimination.