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Copyright of Journal of Anhui Agricultural Sciences is the property of Journal of Anhui Agricultural Sciences Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

210Pbex and 137Cs measurements were carried out to trace the variations in soil depth and erosion rates in the cultivated and reforested land, aiming to explore the changes of soil retention due to the construction of the “Three North” shelterbelt program in the north of China. A typical shelterbelt and wind dominant region was selected, particularly on the Bashang Region of Zhangjiakou City, Hebei province, China. The results showed that in the cultivated land, both 137Cs and 210Pbex in the soil profile were uniformly distributed, due mainly to the mixing effect of tillage. In the reforested land, the 137Cs and 210Pbex concentrations in the 0-0.05 m soil layers were obviously higher than those in the other depth soil layers. There were roughly uniform concentrations of 137Cs and 210Pbex from 0.05 m to 0.15 m of the upper 0.15 m soil layer. It infers that the 137Cs and 210Pbex profile of soil can be changed after reforestation, thereby posing a great challenge on the use of 137Cs and 210Pbex to estimate the variation in soil erosion rates under the conditions of reforestation. A revised 210Pbex model of soil erosion in the reforested land was proposed using the 210Pbex mass balance equation in the temporal change trends of 137Cs and 210Pbex profiles. In the 137Cs proportional model, the mean soil erosion rates of reforested and cultivated land were 27.94±11.92 t/(hm² ·a) and 29.11±14.42 t/(hm² ·a). In the revised 210Pbex conversion model, the soil erosion rates of reforested and cultivated land were 82.16±14.36 t/(hm² ·a) and 68.55±22.11 t/(hm² ·a) before the construction of Three-North shelter forest, whereas, those were -41.28±33.91 t/(hm² ·a) and -8.52±47.32 t/(hm² ·a) after the constructed. It indicates that the 137Cs tracing can be used to characterize the average soil erosion rates and deposition rates on the slopes since 1963. Nevertheless, the 210Pbex tracer technology can be used to trace the variations in soil erosion rates before and after the shelter forest was constructed. In addition, the wind erosion rates of cultivated and reforested land obviously declined, due to the construction of Three-North Shelter Forest, where the cultivated and reforested land have been transformed from erosion zone to deposition zone in the study area. [ABSTRACT FROM AUTHOR]

Copyright of Natural Gas Geoscience is the property of Natural Gas Geoscience and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Closed cultivation is a new type of cultivation model, which is widely used in solar greenhouse, and it uses EC as the performance index of the regulation process of nutrient solution. In the study, a dynamic analysis was conducted on the regulation process of closed culture nutrient solution with two-step mixed fertilizer characteristics. PID control algorithm was used to control the regulation process of the nutrient solution, and the effects of 6 factors on control process were analyzed through comparative experiment. The results showed that it was difficult to use a precise model to characterize the fertilizer mixing process, since the output liquid flow rate, the fertilizer concentration and the PID parameters had great influence on the control effect of the two-step mixed fertilizer system. Experiments were carried out to find the effect of different output liquid flow rates, fertilizer concentration and the PID parameters, on PID control model. The results were obtained using the fixed variable method and orthogonal tests, under the target electrical conductivity (EC) of 2.3. The experimental results showed that the time of the system decreased with the decrease of the output liquid flow rate or the increase of the fertilizer concentration. Duration of system oscillation and overshoot amount increased with the decrease of the output liquid flow rate or the increase of the fertilizer concentration. Keeping the fertilizer concentration and the PID parameters (obtained under the condition that the output liquid flow rate was 4 m3/h and the fertilizer concentration was 4 channels) unchanged, and the target EC of 2.3, the duration of system oscillation was changed from 15 s to 125 s while the output liquid flow rate was changed from 10 m3/h to 4 m3/h, and, the stable time was changed from 180 s to 205 s and the overshoot was changed from 1% to 20%. Keeping the output liquid flow rate and the PID parameters (obtained under the condition that the output liquid flow rate was 4 m3/h and the fertilizer concentration was 4 channels) unchanged and the target EC of 2.3, the duration of system oscillation was changed from 40 s to 125 s while the number of the fertilizer opening channel was changed from 1 channel to 4 channels, the stable time was changed from 255 s to 205 s, and the overshoot was changed from 3% to 20%. According to the different executive agencies and environmental factors, it was necessary to adjust the PID parameter of the system to achieve better control effect. The closed cultivation system ran with high efficiency and stability using the adjusted PID parameters. According to the test results and analysis, the optimal output liquid flow rate and the concentration of the fertilizer solution in closed culture system with two-step mixed fertilizer were 6 m3/h and 200 g/L, respectively. Under this condition, the PID control parameters were adjusted, and the stability time of the system was 100 s, the overshoot was 3%, and the duration of oscillation was 25 s. In summary, the nutrient solution of the closed type cultivation system with double mixed fertilizer could be regulated by the PID algorithm to achieve stable and efficient operation, which provided a reference for the regulation. [ABSTRACT FROM AUTHOR]

As the most important procedures during sugarcane harvesting, leaves cleaning and tails severing are influenced by different growth height and lodging status, and the operating speeds of the rollers not only affect the operating efficiency of the sugarcane harvester, but also influence the quality of harvesting. In order to investigate the effect laws on the quality of peeling leaves and breaking tails of leaf-crushing impeller, leaf-cleaning impeller and tail wheel, the leaf-crushing and tail-breaking system was designed and manufactured for sugarcane harvester test bench after sugarcane harvesting. In the system, elastic wire springs were arranged uniformly on the leaf-crushing impellers, the outer edge of the leaf-cleaning impeller were installed with rubber plates, and the severing tail components on the tail wheels were elastic rib. As the test bench works, the rolling leaf-crushing impeller, leaf-cleaning impeller and tail wheel lacerated and peeled leaves attached tightly on the canes by producing centrifugal and frictional force. According to the mechanical properties that anti-deformation and impact resistance of the tails were significantly lower than other parts, the anti-float mechanism was designed for breaking tails, the groove of the circular arc can prevent the lateral movement and ensure the smooth transportation of the sugarcane. The experiments of peeling leaves and breaking tails of sugarcanes were conducted in Zhejiang University, 2015. A quadratic general rotary unitized design was carried out with leaf-crushing impeller speed, leaf-cleaning speed and tail wheel speed as experimental factors, and with non-cleaning rate, tail broken rate, skin broken rate and non-break rate as experiment indices. By using SAS 9.3 regression analysis method, response surface method and combined with nonlinear optimization calculation method, the working parameters were calculated optimally, and the optimal factor combination was established. The results indicated that, the tail-broken rate and skin broken rate were influenced by the speeds of the three impellers significantly, however, the non-break rate was influenced by the speed of tail wheel only, but it had no effect on the non-cleaning rate. The contribution rate order of non-cleaning rate was leaf-crushing impeller speed, leaf-cleaning speed and tail wheel speed. The contribution rate order of tail broken rate was tail wheel speed, leaf-crushing impeller speed and leaf-cleaning speed. The contribution rate order of skin broken rate was tail wheel speed, leaf-cleaning speed and leaf-crushing impeller speed. The contribution rate order of non-break rate was tail wheel speed, leaf-cleaning speed and leaf-crushing impeller speed. The optimum parameter combination of the test bench after optimization was 512.9 r/min of leaf-crushing impeller speed, 418.8 r/min of leaf-cleaning speed and 307.0 r/min of tail wheel speed. At this level, non-cleaning rate achieved theoretical optimum value of 4.98%, tail broken rate was 88.39%, skin broken rate was 5.19% and non-break rate was 96.21%.Verification experiment showed that the experimental value of non-cleaning rate was 4.86%, tail broken rate was 90%, skin broken rate was 4.78% and non-break rate was 97.5%, which indicated that the experimental values were consistent with predicted results, and regression models established by the experiment were appropriate, which can provide references to design whole-stalk sugarcane harvester and improve the harvesting quality. [ABSTRACT FROM AUTHOR]