共查询到20条相似文献,搜索用时 140 毫秒
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本文用导纳圆图法和谐振导纳计算法,分别对用于超声清洗和塑料焊接的两个振动系统的电声效率进行了测量。结果表明在小信号和功率输出下,其电声效率基本相等。测量误差不超过±15%。为通过电声效率和电功率测量,确定功率超声振动系统的输出声功率提供了可能途径 相似文献
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铌酸锂换能器在超声基准装置中的应用 总被引:1,自引:0,他引:1
针对超声基准装置量传范围较窄且现存超声功率基准装置电测系统中高频电压表不易于溯源等问题,利用压电材料能够将电能转变为机械能的效应原理,根据铌酸锂材料的结构特性,对超声基准装置的关键部件超声换能器及匹配电路进行了改造.改造后的基准装置准确度得到了提高,量传范围得到扩展,新换能器一定程度上解决了装置的高频高压溯源问题,确保了基准装置能在国际超声功率溯源体系中处于领先位置. 相似文献
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研究了频率为20 kHz的超声作用在圆柱形料腔中出现声流现象时超声空化效应的空间分布特性。结合大振幅声源条件下的声辐射力,对声场内的声流现象进行了仿真分析,获取了不同超声功率和液位高度下的声流速度场分布,初步探究了声流条件下空化气泡的运动分布规律。采用超声空化效应的声致化学发光实验,对比研究了有、无声流条件时超声空化效应的空间分布特性。结果表明:功放电流高于80 mA(电功率为17.6 W)时,超声场可形成稳定的声致流动现象且可有效提高其声能辐射效率,大大增加了空化效应的作用区域,进而提高了声化学反应效率;声流条件下料腔内超声空化效应的分布区域与超声功率(振幅)、料腔液位高度相关,功放电流从40 mA(电功率为8.8 W)增加至120 mA(电功率为26.4 W)时,空化面积占比提高了100.86%,液位高度为60 mm时的空化面积占比较50 mm和70 mm时分别提高了13.11%和73.91%,提高超声功率及选择合理的料腔液位高度,可有效提高空化气泡扩散距离,增大空化分布面积;对于固定形状及尺寸料腔中的声场,声流速度达到一定阈值时,会出现空化效应增强,空化效应增强区域位于大于声流速... 相似文献
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针对风电功率时间序列具有高度随机波动性而无法精准预测的问题,提出一种基于完备集成经验模态分解(CEEMD)、Granger因果关系检验和长短时记忆网络的新型混合预测方法用于预测风电功率。首先,为研究风电功率和风速的隐性相关性,通过CEEMD算法对风电功率和风速时间序列分别进行序列分解,实现双层分解。其次,通过Granger因果关系方法对各风速分量与各风电功率分量进行因果关系检验,分析风电功率分量与各风速分量间的相关性,以此实现各风电功率分量的输入变量选择。最后,采用长短时记忆网络对各风电功率分量进行预测,并集成得到最终的风电功率预测结果。通过风电厂的实际数据进行了试验,并与多个应用广泛的经典模型进行对比,结果表明该方法的预测精度取得了大幅度提高,能够对风电功率实现精准预测。 相似文献
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魏超 《中国新技术新产品》2022,(20):76-79
该文针对风电功率的强非线性、大波动性特点,提出一种支持向量机(SVM)短期风电功率预测方法,并给出了具体的建模过程和流程。最后选用国内某风电场的实际运行数据进行验证,并与传统的BP神经网络算法进行了对比,结果表明:该文提出的风电功率预测方法能更好地跟踪风电功率的变化,而且该预测模型的预测精度更高,能更好地提供风电功率预测数据。 相似文献
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Jinn-Chang Wu Hurng-Liahng Jou 《IEEE transactions on instrumentation and measurement》1995,44(4):919-922
In this paper, a new power factor measurement method is proposed. The proposed method is implemented by an analog electronic circuit. Its response time is less than a half-cycle. The test results show that it can measure the power factor of the measured load quickly and accurately, and its response time is superior to the conventional power factor measurement methods 相似文献
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The problem of measuring total power in a new type of astronomical instrumentation, the hybrid spectrometer, is examined. Errors in the total power measurement cause platforming of the spectra, whereby entire sections of the resulting spectra are lifted above or dropped below the baseline. Some of the error mechanisms are examined, particularly in reference to using the zero delay (zerolag) correlation channel. An alternative method that uses the occurrence frequency of quantization states to measure power is suggested 相似文献
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为了准确地测量和分析电力系统中的谐波参数,在分析了常用的几种谐波测量方法的基础上,提出了一种基于FFT数字倍频整周期采样的电力系统谐波参数的测量方法.研制了以高性能ARM Context-M3内核的STM32微处理器为核心的电力系统谐波检测仪.检测仪具有测量基波和各次谐波的电压、电流绝对值的功能,并且能够测得谐波含有率、功率因数、功率和基波频率等其他参数,实现了对电力系统谐波参数的实时监控. 相似文献
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介绍了一种基于量热法的平面换能器声功率测量的方法。先将超声辐射入真空绝热容器内的蓖麻油中,使其温度升高。用热电偶并联测量蓖麻油的平均温升值,计算出蓖麻油所吸收的热能,进而求得换能器的声功率。测量结果表明,在换能器两端电压峰峰值为120V时,用本方法重复10次测得声功率的平均值为5.09W,相应的用辐射力法测得声功率的平均值为6.06W,两者相差16%。该方法的其综合不确定度为±9.3%。此方法使用设备简单且准确性较好,是超声功率测量的一种简单有效的途径。 相似文献
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本文介绍了微机控制的大功率超声清洗机研制的一些技术问题,探索了单片机在功率超声中的应用,提出了大功率超声振动子的一种新的设计方法,解决了一些影响振动子性能的关键问题,对于楔形工具头的超声振动子平均振幅的测量以及与同类机型的比较成为可能,文中还给出了部分比较曲线,实际测量证明,本文所述的系统比同类进口机平均振幅提高一倍以上,对工件的清效果明显优于进口机。 相似文献
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New method for reactive power and energy measurement 总被引:1,自引:0,他引:1
Djokic B. Bosnjakovic P. Begovic M. 《IEEE transactions on instrumentation and measurement》1992,41(2):280-285
The properties of an electronic reactive power and energy measurement method based on a frequency-controlled power-to-pulse-rate conversion are analyzed. The reactive power and energy measurements can be efficiently performed by using a simple integrating circuit as a phase shifter, and frequency-controlled analog-to-pulse-rate converter. A low value of the output pulse rate should not be considered as an inherent disadvantage of the method. By introducing a phase-locked loop in order to achieve high pulse-rate output, the benefit of high resolution is added to the method. The improved electronic structure for the measurement can be implemented in the design of reactive power and energy standards. For precision var-hour meters based on the proposed method, it is possible to have an efficient error-checking and adjustment procedure. The proposed method allows reactive power and energy measurement to be made in single- and poly-phase, symmetrical and unsymmetrical, and balanced and unbalanced networks 相似文献
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为了解决在应变测量中需要的高精度、低干扰并具有相对大的驱动能力的激励源产生的问题。采用可编程基准源和驱动两级电路,通过可编程的DAC生成电压基准,再通过驱动电路,程控选择电压激励源和电流激励源的生成和输出。所设计的程控精密激励源具有体积小、精度高、功耗低、配置灵活的特点。实际应用表明,本设计达到了技术方案要求并已成功应用于实际的应变测量之中。 相似文献
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A novel autofocusing algorithm using the directional wavelet power spectrum is proposed for time delayed and integration charge coupled device (TDI CCD) space cameras, which overcomes the difficulty of focus measure for the real-time change of imaging scenes. Using the multiresolution and band-pass characteristics of wavelet transform to improve the power spectrum based on fast Fourier transform (FFT), the wavelet power spectrum is less sensitive to the variance of scenes. Moreover, the new focus measure can effectively eliminate the impact of image motion mismatching by the directional selection. We test the proposed method's performance on synthetic images as well as a real ground experiment for one TDI CCD prototype camera, and compare it with the focus measure based on the existing FFT spectrum. The simulation results show that the new focus measure can effectively express the defocused states for the real remote sensing images. The error ratio is only 0.112, while the prevalent algorithm based on the FFT spectrum is as high as 0.4. Compared with the FFT-based method, the proposed algorithm performs at a high reliability in the real imaging experiments, where it reduces the instability from 0.600 to 0.161. Two experimental results demonstrate that the proposed algorithm has the characteristics of good monotonicity, high sensitivity, and accuracy. The new algorithm can satisfy the autofocusing requirements for TDI CCD space cameras. 相似文献