基于多种深度学习算法的田间玉米籽粒检测与计数

为快速准确获取玉米收获过程中遗失籽粒数信息,进行收割损失调节等管理,对比评估了单阶段和两阶段主流目标检测网络对田间玉米籽粒计数的性能。首先,利用RGB相机获取包含不同背景和不同光照的图像数据,并进一步生成数据集;其次,构建籽粒识别的不同目标检测网络,包括Mask R-CNN、EfficientDet-D5、YOLOv5-L、YOLOX-L,并利用所采集的420幅有效图像对构建的四种网络进行训练、验证、测试,图像数分别为200、40和180幅;最后,依据测试集图像的识别结果进行籽粒计数性能评价。试验结果表明,YOLOv5-L网络对测试集图像检测的平均精度为78.3%,模型尺寸仅为89.3 MB;籽粒计数的检测正确率、漏检率和F₁值分别为90.7%、9.3%和91.1%,处理速度为55.55 f/s,识别与计数性能均优于Mask R-CNN、EfficientDet-D5和YOLOX-L网络,并对具有不同地表遮挡程度和籽粒聚集状态的图像具有较强的鲁棒性。深度学习目标检测网络YOLOv5-L可实现实际作业中玉米收获损失籽粒的实时监测,精度高、适用性强。     

新农村建设中失地农民问题的探讨

在国家的新农村建设政策中,“三农问题”被提到了一个很高的高度,然而在现实中的城市化和工业化过程中,却不可避免的出现了大量的失地农民,失地农民已经成为中国最弱势、最缺乏保障、最边缘化的群体,成为了影响我国社会稳定的巨大的不稳定因素,如何解决和处理好失地农民安置问题已经变得越来越重要,本文通过分析提出一些见解。     

福建耕地占用及其分布研究

从耕地占用这一角度出发,分析福建省耕地占用现状及趋势,并应用2005年的数据采用聚类分析对福建省耕地占用分布聚为4类,分析4类地区的发展方向。     

青海湖地区耕地资源生产潜力及可持续利用分析

利用逐步订正等方法,结合本地区自然、社会和经济统计资料,对青海湖地区耕地资源不同层次作物生产潜力、潜力总量进行了估算,分析了青海湖地区影响作物生产潜力的限制因子。结果发现,热量和水分因子是青海湖地区影响作物生产潜力的主要因子,现有耕地的最大粮油生产潜力总量为12165165kg。在此基础上计算了各层次的耕地生产潜力利用率,对影响该地区耕地生产潜力的因子进行分析。最后提出了青海湖地区实现耕地生产潜力可持续利用的对策。     

A shifting cultivation land use system under population pressure in Zambia

The status of chitemene shifting cultivation, in northern Zambia was investigated and reviewed. This paper presents results concerning (a) changes in soil nutrients under chitemene shifting cultivation, (b) the relationship between population density and deforestation and (c) how the chitemene shifting cultivation system has survived under conditions of overpopulation relative to the critical population density.In the chitemene shifting cultivation system crops are grown in a small ash garden made by burning a pile of wood cleared from a larger area. The burning increased soil NH₃–N content by 40–50%, with a further increase of 15% after 262 mm of rainfall. In contrast, the soil in unburnt plots lost up to 30% NH₃–N. The content of other major nutrients, such as, P,K, Ca, Mg, and Na also increased in the top soil immediately after burning. The increase in soil NH₃–N after burning is attributed to the reduction in microbacterial activity. These soil nutrient changes appear essential in the production of finger millet.However, the growing rural population in the chitemene shifting cultivation region of northern Zambia has caused deforestation which has resulted in the reduction of (a) the length of the fallow period from 25 years to 12 years, (b) the per person woodland requirement of m 1.1 ha to 0.53 ha and (c) the frequency of clearing new chitemene gardens from yearly to once in two years. These responses to diminishing wood resources have artificially increased the population carrying capacity from 2.4 to 18.7 persons per km². This has enabled the survival of the chitemene shifting cultivation land use system in northern Zambia.     

江苏粮食安全问题的目标定位与对策

本文阐述了江苏粮食安全的目标定位,提出了基于小康水平的粮食安全观点,分析了江苏粮食生产的现状、中长期粮食需求及面临的挑战,进而有针对性地提出了若干对策措施。