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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

Simulation of dust emissions in Hebei Province based on CLM4.5 soil wind erosion model

WANG Xiaowei;WANG Wei

Transactions of the Chinese Society of Agricultural Engineering,2018,Vol 34,No. 08

With the continuous development of the economy and society, the problem of air pollution in China is becoming more and more serious especially in Hebei Province. Currently, Hebei Province has been one of the most serious areas of air pollution in China. The wind-blown dust, emitted from the earth’s surface to the atmosphere, has become one of the main components of air pollutants. The wind-blown dust has significant impacts on atmospheric phenomena and consequently on air quality. The wind-blown dust not only causes atmospheric pollution, but also changes the radiation balance of the ground and the acidity or alkalinity of the aerosol. It not only affects human health but also causes changes in the global climate system and ecosystem. In order to evaluate the PM 10 of atmospheric pollutants in Hebei Province caused by wind-blown dust, in this article, we set up a parameter system of wind-blown dust production by Community Land Model 4.5 (CLM4.5), using the remote sensing data, the ground meteorological data, the data from Land Data Assimilation System and from the Land Surface Satellite Products with 1 km spatial resolution. The factors affecting the wind-blown dust include soil texture, wind speed, soil moisture, surface roughness, and the proportion of bare soil determined by vegetation coverage, surface freezing ratio, snow cover ratio, lakes and wetland ratio. Wind speed, soil moisture, vegetation coverage, snow cover area and freezing ratio change greatly with the seasons, so they are the sensitive factors of the wind-blown dust. This study provides the first estimate of the fine-scale spatial and temporal distribution of dust emission of Hebei Province. The result shows that the annual dust emission flux of PM 10 was 1.02 t/hm 2 in Hebei Province in 2013. The highest monthly emission flux was 0.28 t/hm 2 in March, accounting for 27.6% of the whole year, and the lowest was July, accounting for only 0.2% of the whole year. The dust emission flux of spring was the highest, 0.55 t/hm 2, the summer was the lowest, 0.015 t/hm 2, the autumn was 0.18 t/hm 2, and the winter was 0.28 t/hm 2. This shows an obvious seasonal change. There are obvious regional differences about dust emission flux. In Hebei Province, the coastal plain of Cangzhou and Bashang plateau were the areas with highest dust emission flux, the annual emission flux of which was 5.365 and 3.542 t/hm 2 respectively. The following areas were the coastal plain of eastern Hebei and basins of northwestern Hebei mountains. Taihang Mountain piedmont plain was the lowest area, the annual emission flux of which was 0.20 t/hm 2. The results above show CLM4.5 soil wind erosion model can well simulate the characteristics of spatial and temporal change in Hebei Province. Compared the initial data of CLM4.5 with our study data, it presents the spatial resolution of initial data is very low, and not suitable for the simulation of the small area. In contrast, the local parameters we used including vegetation coverage, wind speed, soil moisture, the proportion of bare soil, lakes and wetland ratio data with high spatial resolution (1 km) improve the accuracy of the simulation results. This paper is not only meaningful for evaluating the PM 10 from wind-blown dust in Hebei Province, but also the first application to estimate the dust emission flux in the fine scale by CLM4.5.

Design and experiment of bionics pit shape grinding roller for improving wear resistance and crushability

XI Peng;CONG Qian;TENG Fengming;GUO Huaxi

Transactions of the Chinese Society of Agricultural Engineering,2018,Vol 34,No. 08

Cement is a basic material, which plays an important role in ensuring the national economic construction of China. Cement grinding roller press plays an important role in cement production and grinding process. The grinding roller is the key component on the grinding roller press and the abrasion loss is quite large. Therefore, increasing the wear resistance and reducing the abrasion loss of the grinding roller press will bring huge economic benefits to cement production. Organisms have evolved a large number of non-smooth surface structures in the process of natural selection, such as the scale structure on the surface of the pangolin, the fringe structure on the shell surface, and the blocky protuberance structure on the surface of the lizard. These non-smooth structures play an important role in improving the wear resistance and reducing the abrasion of biological surfaces so as to improve the wear resistance and fragmentation of the cement grinding roller press. Based on the excellent wear resistance and drag reduction characteristics of the non-smooth surface structure and guided by the bionics non-smooth theory, the bionic pit shape structures with different depths, different diameters, different axial spacings and different circumferential angles were designed on the surface of grinding rollers according to the working principle and actual size of the grinding roller press. Each factor was selected at two levels, namely the factors of the pits arranged according to the orthogonal experimental design method, and the grinding roller machined according to the orthogonal experimental design. The wear test of the grinding roller after processing was carried out. The composition and structure of the test bench were basically the same as the actual roller press. Two relatively rotating grinding rollers were driven by motors. The grinding rollers extruded the abrasive quartz sand in the middle of them. The wear condition was judged by measuring the mass loss. The test results showed that the reasonable bionic pit structure could significantly improve the wear resistance of the grinding roller. The wear resistance of the grinding roller was improved by 29.06% compared with the standard grinding roller. In order to explore the wear mechanism of the bionic grinding roller, we conducted the force analysis of the grinding roller by finite element software. The reasonable bionic pit shape structure could effectively reduce the stress in the inner subsurface and the stress distribution of the grinding roller surface. It could also reduce the stress gradient and optimize the force on the grinding roller surface so as to reduce the abrasion and improve the wear resistance. The crushing test of the grinding roller was carried out according to the orthogonal experimental design. The crushing rate of quartz sand was used as a criterion for evaluating the crushability. The bionic pit structure could effectively improve the crushability of the grinding roller according to the test results. Its crushability was increased by 18.7% compared with the standard grinding roll. Combined with the explicit dynamic, it was found that maximum extrusion pressure was an important factor affecting the crushability of the grinding roller, and maximum extrusion pressure was an important factor affecting the crushability of grinding roller. It was the best grinding roller with both wear resistance and breakage when the diameter of the pit was 8 mm, the depth of the pit was 2 mm, the distance of the axial pit was 16 mm and the number of circumferential pit was 12. The single particle crush test of the bionic grinding roller was carried out and the whole process of quartz sand breakage was recorded by a high-speed camera. Compared with the standard grinding roll, the bionic pit shape grinding roller could seize quartz sand quickly, form transient stability structure, and reduce the sliding probability of quartz sand on the grinding roller surface. The probability of scratch on the grinding roll surface was reduced by the quartz sand. The bionic pit shape structure made the single point support become multi-point support in the process of extruding quartz sand by the grinding roller. The extrusion force dispersed which was the important reason to improve the abrasion resistance and crushability of the grinding roller press.