As one of the most important parameters in the measurement of tractor slip ratio, wheel speed signal must ensure its accuracy in order to accurately measure the tractor slip ratio. Noises make tractor wheel speed signal a significant fluctuation, which may cause control system failure. Fault points elimination method suitable for tractor wheel speed signal was determined based on the characteristics of tractor wheel speed signal during working process. Meanwhile, soft-hard compromise threshold function wavelet denoising method is designed according to the characteristics of tractor wheel speed signal and trials. We use Carsim simulation software to get actual tractor wheel speed signal, and add white noise which SNR (signal to noise ratio) is 60 to the original signal. From the results of several wavelet denoising methods we can conclude that the soft-hard compromise threshold function wavelet denoising method is better than any other ordinary wavelet denoising methods. The SNR of denoised signal is 56.440 and the MSE (mean square error) is 0.0042. The wavelet transform denoising method is feasible to remove noise from tractor driving wheel speed signal.
数控加工技术随着现代科学技术的不断发展和进步已经得到了进一步地改进优化，现代制造业对数控技术有着越来越高的依赖度，为此，需要加强提升数控加工技术水平，推动机械制造行业的进一步发展，通过提升数控加工技术水平保证制造高质量的产品，促使企业稳定平稳地发展。
The talent training objectives is Combined under the background of new engineering in this paper, the excellent experience was drew of relevant mixed teaching models at home and abroad, teaching reform and exploration around the course "Automotive Engine Principles" was carried out, and an online and offline mixed teaching model and its implementation path and method is proposed, a reference scheme is provided for the informatization teaching of "Principles of Automobile Engines".
Based on the practice of online teaching since the epidemic in this paper, the teaching of "Principles of Automobile Engines" was taken as a platform, the excellent experience of domestic and foreign multi-mixed teaching models was drew, and the characteristics of contemporary college students’ Internet learning was combined. The design and exploration of the online and offline multi-mixed teaching mode is applied to the teaching practice of the professional course of "Automotive Engine Principles" in vehicle engineering. The results show that the teaching effect is good and has certain reference value.
为有效减少柴油机在工作过程所产生的排气噪声,本文提出一种并联对冲式消声器结构方案,对其受结构因子声学性能的影响规律进行研究,探究进排气管管径、进排气管长度、排气内插管长度、对冲管长度、对冲管数量等结构因子在0-4000Hz频域内对传递损失的影响规律.研究发现,较小的进气管管径、较少的对冲管数量、较小的对冲管管径以及较长的对冲管长度均可以有效提高并联对冲式消声器传递损失,较长的排气内插管长度可有效提高中低频段传递损失,而排气管管径对并联对冲式消声器的声学传递损失影响不大.
