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201.
A fully digitized electric vehicle direct torque control system with DSPTMS320LF2407 controller is described. The system hardware and software structures are presented. The performance of the direct torque control system is studied by simulation with MATLAB. Based on the simulation of the induction motor, waveform of current, speed, torque and flux are obtained. The testing results are also presented. Experimental results show that the design is feasible. 相似文献
202.
The research of neural network has been maturated both in theory and practical application since 1980's, and also been employed into the prediction and analysis of nonlinear time series signal in the field of signal process system. Concerning with the problem of time series signal prediction based on traditional neural network, such as black box, poor accuracy, and facing the shortage of post knowledge, this paper presents a different neural network prediction model from the traditional ones, based on intelligent neural cell model and employing the iterative prediction method. Through the example on stock price prediction, the prediction accuracy and practical value are proved. 相似文献
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不同激素培养基对小麦×玉米杂种幼胚发育的影响 总被引:1,自引:0,他引:1
本研究结果表明,采用2,4-D浸穗法结合低浓度激素培养进行小穗培养,可以明显改善小麦和玉米杂交种颖果、幼胚及胚乳的发育状况,得胚率由2.1%提高到12.0%;同时表明低浓度激素对杂种发育有着明显的调节作用,但2,4-D和GA优于KT。 相似文献
205.
施加钙对锶胁迫下麻疯树生长及生理生化的影响 总被引:1,自引:0,他引:1
为了研究外源钙对锶胁迫下麻疯树生理生化的影响,本试验以麻疯树为研究材料,施加88Sr2+(200mg·kg-1)与不同浓度Ca2+(0、100和200mg·kg-1),处理30、70和120 d后取样,测定生长指标及生理生化等指标,以此研究Ca2+对麻疯树所受Sr2+胁迫的调节作用。结果表明:施加Ca2+促进了株高和叶面积增加,并在前期大量促进叶绿素的合成;最大荧光Fm和最大光化学效率Fv/Fm等荧光参数随着处理时间逐渐升高并在120 d时显著高于对照组,表明Ca2+降低了胁迫对PSII反应中心的损害;施加Ca2+后幼苗SOD、POD和CAT活性明显降低,说明88Sr2+胁迫对抗氧化防御系统的刺激有所降低;丙二醛与脯氨酸含量的降低也表明施加Ca2+缓解了幼苗所受88Sr2+胁迫。通过对比,低浓度Ca2+能够更好地缓解胁迫,对株高、株茎和叶面积的促进作用明显高于高浓度Ca2+处理。在处理30 d时,低浓度Ca2+对叶绿素含量、Fv/Fm和电子传递速率ETR的调节效果更明显。因此,Ca2+可以在一定程度上缓解88Sr2+对麻疯树幼苗的胁迫,并且低浓度Ca2+的缓解效果更明显。研究结果为木本植物修复放射性核素污染土壤提供了一定的科学依据。 相似文献
206.
Kenji Ohse Kenji Tamura Haruo Tanaka Teruo Higashi 《Soil Science and Plant Nutrition》2005,51(1):37-42
At Mt. Hirugatake in the Tanzawa Mountains, Kanto district, Japan, the deciduous broadleaved forests have rapidly declined. In our previous studies, we reported that the amount of soil organic matter had significantly decreased at the early and final stages of forest decline, and that the soil microbial biomass also showed a large decrease at these stages, suggesting that the composition of soil organic matter might have also changed with forest decline. To clarify the influences of forest decline on the composition of soil organic matter, the amount of humic substances, optical properties of humic acid, and the amount of soil carbohydrates in surface soils at different stages of forest decline were investigated. The amounts of humic acid and fulvic acid decreased to a lesser extent at the early and middle stages of forest decline, and showed a significant decrease at the final stage. As the amount of humin significantly decreased at the early stage, it was plausible that the distinct decrease in the total carbon content of the soil surface horizons at the early stage of forest decline was induced by the decrease in the amount of humin, and at the final stage, by the decrease in the amounts of humic acid and fulvic acid. The amount of soil carbohydrates did not change appreciably with forest decline although the soil organic matter content markedly decreased. It was suggested that most of the carbohydrates in the soil surface horizons were in a stabilized form consisting of complexes with humic substances, metals, and minerals, and would not be affected by the environmental changes associated with forest decline. 相似文献
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提出了基于声学的蚕茧无损检测新方法,研究了利用小波包原理提取噪声信号的特征值的方法。噪声信号经过小波包分解后,得到各频段内的信号,将各频段内信号的能量谱作为识别蚕蛹质量的特征值。结果表明,通过小波包原理提取的能量谱特征值能有效地识别出蚕蛹的质量,解决了蚕茧无损检测过程中难找出与蚕蛹质量有关的信号特征值的难题。 相似文献