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Saied Mostaghimi J. Kent Mitchell 《Journal of the American Water Resources Association》1983,19(4):605-612
ABSTRACT Laboratory experiments were conducted to study effects of trickle emitter discharge rate on the distribution of soil moisture in a silty-clay loam soil. Both pulsed and continuous irrigation treatments were studied. A simulation model was used to evaluate the results obtained in the laboratory. The agreement between the predicted and measured soil moisture distribution patterns was quite good. For both pulsed and continuous applications, increasing trickle discharge rate resulted in a decrease in the horizontal component and an increase in the vertical component of the wetted soil profile. Compared to the continuous treatments, pulsed applications resulted in significant reduction in water loss below the root zone. Pulsed applications rates can replace continuous small discharge rates to reduce irrigation water runoff problems on heavy soils and with restricted infiltration allow the use of larger emitter orifices to decrease potential clogging of the trickle system. 相似文献
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基于小波包分析的爆破振动危害评价初探 总被引:2,自引:0,他引:2
结合振动主频的质点振速判据是对单一质点振速判据的补充和完善.但该判据的振动主频是通过FFT变换的频谱分析的方法获得的,不能体现爆破振动波形的多主振频带特征,而且由于方法本身的局限性使得主振频率发生的时间段不能确定.小波包分析法则克服了FFT频谱分析的局限,有效地分解和重构原始信号中的细节信号,并将其作为评价不同频率细节信号的爆破振动危害效果的基础.本文针对爆破振动的小波包分析法进行了研究,对各小波包细节信号加载条件下的不同危害效果进行了讨论,得到了相应的质点振速判据,并将该方法所得到的判据与FFT变换的频谱分析方法所得到的判据进行了对比.结果表明,基于小波包分析法的质点振速判据更加符合爆破振动危害的真实情况. 相似文献
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厄尔尼诺事件对河南省降水的可能影响 总被引:7,自引:0,他引:7
本文采用小波变换方法分析了近50年来赤道东太平洋月海温距平序列和河南省月降水量距平序列的多层次时间尺度结构,对厄尔尼诺事件和河南降水的周期变化规律进行了对比分析,并讨论了厄尔尼诺对河南降水的可能影响。结果表明,厄尔尼诺事件对河南降水有一定程度的影响;表现为厄尔尼诺年大多对应河南雨涝年,而反厄尔诺年大多对应干旱年;NINO海区SST的冷暖结构和河南降水的旱涝变化之间具有较好的对应关系,而且两者都存在准2年和4-8年的周期变化。 相似文献
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Sheng-Wei Fei 《International Journal of Green Energy》2020,17(10):583-590
ABSTRACT In order to improve the prediction ability for the monthly wind speed of RVR, the hybrid model of empirical wavelet transform and relevance vector regression (EWT-RVR) is proposed for monthly wind speed prediction in this study. Compared with empirical mode decomposition (EMD), empirical wavelet transform (EWT) can obtain a more consistent decomposition and have a mathematical theory. In order to testify the superiority of EWT-RVR, several traditional RVR models are used to compare with the proposed EWT-RVR method under the situation of the same embedding dimensions. The experimental results show that the proposed EWT-RVR method has a better prediction ability for monthly wind speed than RVR. It can be concluded that the proposed EWT-RVR method for monthly wind speed is effective. 相似文献
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吐鲁番盆地的特殊气候条件,为经济作提供了良好的生长环境,而粮食生产受气候条件和经济作物快速增长的双重制约,发展非常困难,本文分析了吐鲁番地区粮食生产增长态热及制约因素,并应用多种模型对未来粮食变化趋势作了定量和定性的,在此基础上提出了相应的对策。 相似文献
48.
EMMC process for combined removal of organics, nitrogen and an odor producing substance 总被引:2,自引:0,他引:2
In order to improve the process performance regarding the removal of organics, nitrogen, and an odor-causing compound (sulfide) contained in domestic wastewater, an entrapped-mixed-microbial cell (EMMC) with and without humic substances for both fixed and moving carrier reactors and conventional suspended growth culture (i.e. conventional activated sludge process) were investigated simultaneously. Both synthetic (simulated to the organics concentration of general domestic sewage) and actual domestic wastewater were investigated under operational conditions of 12 h of hydraulic retention time (HRT) with 1 h of aeration and 1 h of non-aeration, and 6 h of HRT with continuous aeration, at a room temperature of 25 +/- 2 degrees C. It was found that entrapping humic substances in the EMMC carriers had no impact on the removal of organics, nitrogen, and the odor-producing compound. Additionally, the performance of the EMMC moving carrier system for the removal of these pollutants is similar to that of the EMMC fixed carrier system. In general, the EMMC associated systems which provide high solids retention time achieve a better removal of chemical oxygen demand (COD), nitrogen, and the odor-producing substance than the suspended growth system for both HRTs of 6 h (continuous aeration) and 12 h (1 h of aeration and 1 h of non-aeration). Both the fixed and moving carrier EMMC processes, therefore, have the potential for improvement or replacement of the existing conventional activated sludge process with regard to improving the effluent qualities (such as COD, nitrogen and odor-producing compound) for reuse/disposal. 相似文献
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