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Copyright of Bulletin of Soil & Water Conservation is the property of Bulletin of Soil & Water Conservation 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.)

In order to solve the problem of collision free path planning and system efficiency improvement of multi AGV in dynamic unstable environment, this paper proposed a collision free path planning method based on time window for AGV. Firstly, this paper established a multi-AGV collision avoidance model, combined with the time window model, and divided the collisionfree path planning of multiple AGV into two stages: pre-planning and real-time planning. In the pre-planning stage, this paper calculated the conflict-free time window of multiple AGV and maximized the circulation of AGV in the system. In the real-time planning stage, this paper used the method of changing the AGV' s occupancy priority on the collision avoidance model and local re-planning to dynamically avoid collisions. Finally, a simulation experiment with a smart warehouse as an application case proves that the algorithm can effectively avoid the collision of multiple AGV, increase the circulation of AGV, and has good robustness and flexibility in a dynamic environment. [ABSTRACT FROM AUTHOR]

Sustainable (Green) development has been ever deepening the comprehensive transformation of the social economy at present. The green transformation of cultivated land use (GTCLU) has been one of the key steps towards the modern agriculture. The GTCLU has also been an effective solution to the ecological dilemma of cultivated land use, particularly on a positive response to national development strategies, such as green China and economic transformation. However, such a research is still lacking. In this study, an attempt was made to elucidate the concept of GTCLU, thereby to guide the subsequent activities of cultivated land use for the better improvement of green development. Moreover, the characteristics of GTCLU were also summarized from four aspects: the category of transformation, the causes of transformation, the manifestations of GTCLU, and the evolution form of GTCLU. A green evolution of cultivated land system was then proposed from the perspective of micro production factors, indicating a better starting point for the efficiency of GTCLU in China. As such, the index system of GTCLU was constructed scientifically. Thus, the panel data was collected from the 30 provinces in China from 2003 to 2017. A three-stage DEA-Malmquist and Tobit models were also utilized to calculate the efficiency and affecting factors of GTCLU. The results showed that: 1) The initial result of efficiency of GTCLU from the Malmquist model presented a V-shaped trend of “declining first, then increasing”. Specifically, the efficiency value was less than 1, indicating the green transition was invalid in most years. 2) The SFA regression was selected to remove the influence of environmental factors and random errors. After that, the efficiency value of GTCLU was 1.001, indicating an outstanding GTCLU degree. More importantly, the technological progress was greatly contributed to the efficiency improvement. Specifically, the change of technical efficiency, pure technical, and scale efficiency were the main bottlenecks for the efficiency improvement. 3) There were also the outstanding regional differences in the efficiency of GTCLU in China. The central region presented the best relative efficiency, followed by the northeast and eastern regions, and the western region was relatively the lowest. Meanwhile, there was a fluctuating upward trend in the time series, with an average annual growth rate of 0.84%. 4) The GTCLU efficiency was significantly depended on the agricultural economic level, cultivated land resource endowment, government support, and technology use intensity. A better GTCLU was then required the system, management innovation, as well as the promotion of resource endowment and technology. Specifically, four suggestions were addressed for each region during this time: 1) To take the sustainable development of cultivated land resource endowment; 2) To strictly control the low benefit mode of agricultural economic development; 3) To fully release the vitality of green cultivated land market and the driving force; 4) To continuously strengthen the green elements in the input and output of cultivated land use. [ABSTRACT FROM AUTHOR]

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.)

To systematically investigate the spatial-temporal distribution characteristics of cultivated land use efficiency in major grain producing areas of China from low carbon perspective, this study took carbon emissions resulting from cultivated land utilization, which acted as an undesirable output, into the measurement framework of cultivated land use efficiency, and quantitatively analyzed the spatial pattern and evolution of cultivated land use efficiency in major grain producing areas from 2000 to 2016. Methods applied in this study include SBM-Undesirable model and kernel density estimation. The results showed that: 1) Carbon emissions resulting from cultivated land utilization in the main grain producing areas and each province all showed upward trend at different rates. The absolute growth of carbon emissions from cultivated land utilization in Henan Province ranked the first, whose carbon emissions changed from 487.40104 to 806.99104 t during the period of from 2000 to 2016, with a net increase of 319.59104 t. Carbon emissions resulting from cultivated land utilization in Inner Mongolia and Heilongjiang ranked the second and third, respectively. The absolute growth of carbon emissions resulting from cultivated land utilization in Jiangxi Province ranked the lowest, with a total increase of 59.64104 t during the study period. 2) Cultivated land use efficiency of the major grain producing areas and provinces was reduced significantly when the carbon emissions resulting from cultivated land utilization were taken into account. In the year of 2000 and 2016, the average values of cultivated land use efficiency in major grain producing areas measured by the traditional CCR model were 0.7744 and 0.9179, respectively, while the average efficiency measured by SBM-Undesirable model was 0.6394 in 2000 and 0.8438 in 2016, which was decreased by 0.1350 and 0.0741, respectively. 3) Cultivated land use efficiency in major grain producing areas showed characteristics with significant spatial disparities. As can be seen from the results calculated by SBM-Undesirable model, 13 major grain producing areas can be divided into 3 types, namely, advantage areas, flat areas and disadvantage areas. Each area differed variously in indicators of input and output during the processes of cultivated land utilization. 4) From the results of kernel density estimation, during the study period, cultivated land use efficiency in the main grain producing areas, including advantage areas, flat areas and disadvantage areas all presented characteristics of skewed distribution and polarization. Meanwhile, compared with the density curve in the year of 2000, the change intervals of the density curve of major grain producing areas, including flat areas and disadvantage areas were smaller in 2016, indicating that the regional gap of cultivated land use efficiency in these areas was narrowed in the period of from 2000 to 2016. However, during this period, the change interval of the density curve of advantage areas was not obvious. Under the background of “low carbon development” and “green development”, this study can provide scientific basis and decision-making reference for the efficient and low-carbon use of cultivated land resources in major grain producing areas, which can also be helpful for the sustainable utilization of cultivated land in other regions of China. [ABSTRACT FROM AUTHOR]