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Brief

Transactions of the Chinese Society of Agricultural Engineering, the 1st in Agricultural Engineering, is supervised by China Association for Science and Technology, and sponsored by Chinese Society of Agricultural Engineering. It aims to introduce the latest scientific achievements and developing trends of Agricultural Engineering and provides the academic developments abroad and domestic of the discipline. The scope covers agricultural water-soil engineering, agricultural information and electrical technology, agricultural products processing engineering. The journal is included in EI, JST, Pж(AJ), CA and CSCD.
Editorial Board

Editor-in-Chief
Zhu Ming

Deputy Editor-in-Chief
Wei Xiuju
Zhang Ruihong
Xi Weimin
Wang Liu
Wang Yingkuan
Li Pingping
Ying Yibin
Tong Jin
Yun Wenju
Zhao Chunjiang
Kang Shaozhong

Process of runoff and sediment yield and relationship between water and sand of frozen soil slope in loess area under different rainfall intensities

ZHANG Yang;ZHANG Hui;LI Zhanbin;LI Peng;XIAO Lie;KE Haocheng;CHEN Yiting

Transactions of the Chinese Society of Agricultural Engineering,2018,Vol 34,No. 11

Seasonal freezing-thawing phenomenon occurs mainly in mid-latitudinal region, which is generally characterized by freezing in winter and melting in summer. The middle reaches of the Yellow River are in the middle latitudes, and their climatic conditions meet the requirements of freeze-thaw erosion. The soil erosion during thawing period is a special form of erosion in winter and spring, which is often caused by the combination of water erosion, gravity erosion, and freeze-thaw erosion. During the soil thaw period, due to the poor thawing of slope soil and poor permeability, severe soil and water loss occurred under very small rainfall intensity. Studies in China on soil erosion in thawing seasons are mainly concentrated in the northeastern region. However, there are few studies on the Loess Plateau region in the northwest, and few experiments have been conducted to quantitatively study freeze-thaw erosion on the Loess Plateau. Therefore, in order to study the effect of rainfall on the frozen slope erosion on the Loess Plateau, the difference of erosion between frozen and unfrozen soil under different hydraulic conditions was clarified. Through the indoor simulated rainfall experiment, three kinds of rainfall intensities (0.6, 0.9, 1.2 mm/min) and two kinds of slopes (frozen soil slope and control slope) were used to quantitatively study the process of runoff and sediment yield on slope as well as the relation between the runoff and the sediment under different experimental treatments. The results showed that the time producing runoff on the frozen soil slope was 18.7 and 6.4 min earlier than the control slope under the rainfall intensity of 0.9 and 1.2 mm/min, respectively. The runoff and erosion amount of the frozen soil slope were far greater than that of the control slope. The runoff at the rainfall intensity of 0.9 and 1.2 mm/min was 1.16 and 1.19 times that of the control slope, respectively, and the erosion amount was 10.40 and 6.40 times, respectively. As the rain went on, the slope produced different degrees of rill. The occurrence time of rill on frozen slope was shortened by 18 and 22 min, respectively, compared with the control slope, and the rill erosion on frozen soil slope accounted for 79%–92% of the total erosion amount, which was greater than that of the control slope under the same rainfall intensity. The cumulative runoff and accumulated sediment yield of the two slopes satisfied the linear relationship of y = kx + b, and the k value of the frozen soil slope was 8.48–9.02 times that of the control slope in the interrill erosion stage, while 3.68–7.50 times in the rill erosion stage. The results showed that the rill erosion was the main reason to the increase of soil erosion rate on the frozen soil slope, and the water blocking effect of the freezing layer was the most important factor leading to the advance of the emergence time of rill on the slope. This result is expected to provide some certain reference for the study of soil erosion mechanism.

Design and experiment of hydraulically self-excited vibration subsoiler

WANG Yunxia;ZHANG Dongxing;YANG Li;CUI Tao;LI Yuhuan;LIU Yanwei

Transactions of the Chinese Society of Agricultural Engineering,2018,Vol 34,No. 11

The self-excited vibration subsoilers with springs present the shortages of poor adaptability and failure of vibration in different soil texture because of the constant stiffness and limited adjustment range of pre-tension force. Aiming at improving the working performance of self-excited vibration subsoiler, a new method characterized by hydraulically self-excited vibration source was provided. Meanwhile, the self-excited vibration subsoiler with a hydraulic cylinder was designed. The new subsoiler mainly consists of a fixed mount to connect the subsoiler with the machine frame, a hydraulic cylinder served as the self-vibrating source, a connecting plate to connect the tine and the fixed mount, a press wheel to compact the tilled soil surface thus reducing the water evaporation. The key design parameters of the hydraulic cylinder were determined by establishing the mechanics and kinematics model of the tine: the diameter D = 40 mm and the stroke S = 130 mm. The adjustable system for hydraulic cylinder pressure was set up. The adjustable system consists of two parts: electric control section and hydraulic section. The hydraulic section mainly includes the hydraulic source, an accumulator, a manual reducing valve, and an electromagnetic proportional pressure reducing valve. The hydraulic source can be supplied by the tractor with hydraulic output connector. The accumulator is used to stabilize the system pressure and the electromagnetic proportional pressure reducing valve is used to adjust the working pressure of the hydraulic cylinders continuously and proportionally. The manual reducing valve is set between the electromagnetic proportional pressure reducing valve and the accumulator to obtain desired value closely to the working pressure of the hydraulic cylinder pressure, which is beneficial to avoiding pulse impact caused by the electromagnetic proportional pressure reducing valve adjusting the pressure for the hydraulic cylinder. The electric control section is mainly composed of a controller, a touch screen and a DAC module (digital to analog converter). The electric control section communicates with the hydraulic system through the DAC module that transmits the signal volt from the controller to the analog volt for electromagnetic proportional pressure reducing valve to adjust the working pressure of the hydraulic cylinder pressure. The target value of hydraulic pressure is input to the electric control section by the touch screen. The quadratic regression general rotation combination tests were conducted to investigate the influence of hydraulic cylinder pressure, operating speed and soil cone index on the working performance of hydraulically self-excited vibration subsoiler with a hydraulic cylinder. The traction and variation coefficient of tillage depth were selected as evaluation indexes. The results showed that the soil cone index and the operating speed had positive impacts on the variation index of tillage depth while the working pressure of the hydraulic cylinder pressure had negative impact on the variation index of tillage depth. The variation index of tillage depth was more influenced by the hydraulic cylinder pressure and operating speed than soil cone index. The traction increased with the increase of the operating speed and hydraulic cylinder pressure and decreased after reaching the maximum value. The impact of the factors on the traction was followed with the soil cone index, the hydraulic cylinder pressure and the operating speed. The regression models with the variation index of tillage depth and the traction as the response value respectively were acquired and the optimal combination of parameters was obtained: the hydraulic cylinder pressure of 3.6 MPa, the operating speed of 1.4 km/h, the soil cone index of 1.18 MPa. Verification test was carried out to testify the regression models using the optimal combination of parameters. The traction and variation index of tillage depth were respectively 1 300.70 N and 3.56% that were better than the results of quadratic regression general rotation combination tests, which verified the reliability of the regression model. This study can provide a theoretical reference for the research of self-excited vibration subsoiling machines.