基于逆运动学降维求解与YOLO v4的果实采摘系统研究

为提高采摘设备的执行效率，采用六自由度机械臂、树莓派、Android手机端和服务器设计了一种智能果实采摘系统，该系统可自动识别不同种类的水果，并实现自动采摘，可通过手机端远程控制采摘设备的起始和停止，并远程查看实时采摘视频。提出通过降低自由度和使用二维坐标系来实现三维坐标系中机械臂逆运动学的求解过程，从而避免了大量的矩阵运算，使机械臂逆运动学求解过程更加简捷。利用Matlab中的Robotic Toolbox进行机械臂三维建模仿真，验证了降维求解的可行性。在果实采摘流程中，为了使机械臂运动轨迹更加稳定与协调，采用五项式插值法对机械臂进行运动轨迹规划控制。基于Darknet深度学习框架的YOLO v4目标检测识别算法进行果实目标检测和像素定位，在Ubuntu 19.10操作系统中使用2000幅图像作为训练集，分别对不同种类的果实进行识别模型训练，在GPU环境下进行测试，结果表明，每种果实识别的准确率均在94%以上，单次果实采摘的时间约为17s。经过实际测试，该系统具有良好的稳定性、实时性以及对果实采摘的准确性。     

叶轮出口边对双蜗壳泵压力脉动的影响

泵的叶轮扫掠蜗壳隔舌时产生的压力脉动是引起船用泵振动噪声的原因之一.为尽可能弱化这一影响,分别设计了叶片出口边与前后盖板基本面垂直和倾斜的2种不同形式叶轮,将其配置在相同的双蜗壳中,通过数值计算与样机试验相结合的手段,对蜗壳内9个不同位置的压力脉动情况进行对比分析.结果表明:出口边倾斜的叶轮相比于出口边垂直的叶轮可明显改善蜗壳内次脉动的“驼峰”现象,且可以进一步降低隔舌处主波动的压力峰值;对蜗壳内2个隔舌稍前的位置,出口边倾斜的叶轮反而会使得该点的压力系数幅值明显增大,且该点主波动的周期数发生改变;2种叶轮出口边的不同形式对蜗壳出口位置的压力脉动的影响基本相同;采用出口边倾斜叶轮对改善因叶轮与隔舌间的液流压力脉动是可行的.     

农网配电线路损耗分析

配电网起着输送和分配电能的作用,线路损耗给供电企业造成很大的成本投入,降低能源的利用率。分析配电网线路损耗的原因,提出降低线路损耗的具体措施,以期为配电网节能降耗、安全运行提供参考。     

MBBR和LSP工艺在污水深度处理中的性能探究

指出了MBBR工艺和LSP工艺属于当前应用较多的新型水处理工艺。当将传统的好氧曝气池改造为MBBR工艺时,改造结果表明:COD降低30.8%,BOD 5降低42.8%,氨氮降低25.0%,总氮降低17.2%,SS降低57.9%,总磷降低26.7%;而LSP工艺通过形成复杂的微生物食物链,消耗剩余污泥量,实现对污泥的减量化处理。应用到改造工程中,产泥量降低67.5%,同时能够强化处理系统的生化功能,COD和BOD 5都有明显降低,分别降低了11.7%和12.1%。     

Bats as the main prey of wintering long‐eared owl (Asio otus) in Beijing: Integrating biodiversity protection and urban management

The loss of biodiversity from urbanized areas is a major environmental problem challenging policy‐makers throughout the world. Solutions to this problem are urgently required in China. We carried out a case study of wintering long‐eared owls (Asio otus) and their main prey to illustrate the negative effects of urbanization combined with ineffective conservation of biodiversity in Beijing. Field monitoring of owl numbers at two roosting sites from 2004 to 2012 showed that the owl population had fallen rapidly in metropolitan Beijing. Analysis of pellet contents identified only seven individuals of two species of shrew. The majority of mammalian prey comprised four bat and seven rodent species, making up 29.3% and 29.5% of the prey items, respectively. Prey composition varied significantly among years at the two sample sites. At the urban site the consumption of bats and rodents declined gradually over time, while predation on birds increased. In contrast, at the suburban site the prey composition showed an overall decrease in the number of bats, a sharp increase and a subsequent decrease in bird prey, and the number of rodent prey fell to a low point. Rapid development of real estate and inadequate greenfield management in city parks resulted in negative effects on the bird and small mammal habitat of urban areas in Beijing. We suggest that measures to conserve biodiversity should be integrated into future urban planning to maintain China's rich biodiversity while also achieving sustainable economic development.     

中国草地固碳减排研究现状及其建议

随着经济的快速发展,温室气体的排放量不断增加,加之人类对自然资源的利用强度逐渐增加,导致全球生态系统的固碳能力减弱,大气中的温室气体浓度达到新高,所造成的温室效应已经成为国际社会普遍关注的重大全球性问题。中国草地碳汇资源得天独厚,发展草原碳汇经济成为履行国际承诺、打造碳汇新经济、建设美丽中国的重要载体。综述中国草地固碳减排现状及其影响因素,包括草地碳汇和家畜生产减排研究、气候变化背景下的草地碳汇、人工草地建设等方面,并提出中国草地固碳减排发展建议,以期为中国实现碳达峰、碳中和及草地固碳减排的贡献提供理论基础,为推动我国社会高质量发展、创造高品质生活提供坚实的技术支撑。     

Time course of the incidence/multiplicity and histopathological features of murine colonic dysplasia,adenoma and adenocarcinoma induced by benzo[a]pyrene and dextran sulfate sodium

Benzo[a]pyrene (BP) is mutagenic but noncarcinogenic in the murine colon. Recently, we reported rapid induction of colonic tumors by treatment of CD2F₁ mice with BP (125 mg/kg for 5 days) followed by a colitis inducer, dextran sulfate sodium (DSS) (4% in drinking water for 1 or 2 weeks). However, there are no reports on detailed time course and histopathological features of colonic proliferative lesions in this model. Here, we show the detailed time course of colonic dysplasia, adenoma and adenocarcinoma induced by treatment with BP, DSS, and a combination of the two (BP/DSS). In the colon of mice exposed to BP/DSS, 14.6 dysplastic foci per mouse were present one week after DSS treatment (week 4). The number of dysplastic foci decreased with time to 3.1 at week 9 and thereafter remained almost constant. At week 4, 1.5 adenocarcinomas were also observed, with a marked increase in numbers with time, reaching 29.3 at week 14. In contrast, the number of dysplastic foci induced by DSS alone showed a time course similar to that following BP/DSS treatment; however, only a few tumors appeared. Neither dysplastic foci nor neoplastic lesions were induced by BP only. In mice exposed to BP/DSS, β-catenin was demonstrated immunohistochemically in the nucleus and/or cytoplasm of the tumor cells, and this translocation from the cell membrane was evident in subsets of dysplastic foci. In dysplastic foci induced by DSS alone, β-catenin was absent in the nucleus/cytoplasm. These finding suggest that aberrant β-catenin accumulation in dysplastic foci is associated with tumor progression in this BP/DSS model.     

钢铁企业焦化工序节能减排途径探讨

从焦化技术改进、资源综合利用、余热回收利用三方面探讨了钢铁企业焦化工序节能减排途径。分析了捣固炼焦、干熄焦等技术,为钢铁企业实施节能减排提供参考。     

Effects of artificial light sources on accumulation of phytochemical contents in hydroponic lettuce

Lettuce is grown in different parts of the world and it is beneficial for health. Light condition is one of the most important environmental factor in regulating growth, development, and phytochemical accumulation in lettuce, particularly when lettuce is produced in a hydroponic system. Due to advances in technologies, artificial light sources have become increasingly capable of providing appropriate quality, intensity, and photoperiod of light in hydroponic lettuce production. This review highlights the progress of current research on the effects of artificial light regulation on growth and phytochemical accumulation in lettuce produced in hydroponic systems.     

钾肥种类和施钾时期对油葵产量及品质的影响

为分析钾肥种类和施钾时期对油葵产量以及品质的影响，选取油葵杂交品种陇葵杂3号，采用2因素3水平（2个钾肥种类：氯化钾（F1）、硫酸钾(F2)；3个施钾时期：全部种前基施（T1）、 50% 基施+50%现蕾期追施（T2）、 25%基施+50%现蕾期追施+25%花期追施（T3））随机区组试验设计，于2014-2016年在甘肃省景泰条山农场进行田间试验。结果表明：KCl和K₂SO₄这两个钾肥品种的盘径、千粒重、粗脂肪含量、产油量、亚麻酸含量间没有明显的差异。与施用K₂SO₄相比，施用KCl的产量在2014年显著增加，F1T2的产量较F2T2增加了4.96%，F1T3较F2T3增加了4.06%。出仁率、油酸含量在2015年和2016年显著增加，F1T1的出仁率较F2T1在2015年和2016年分别增加了1.50%、2.99%，F1T2的出仁率较F2T2在2015年和2016年分别增加了1.76%、19.7%；2015年F1T2的油酸含量较F2T2增加了5.92%；2016年F1T3的油酸含量较F2T3增加了9.09%。粗蛋白含量在2014年和2016年显著降低，F2T3的粗蛋白含量较F1T3在2014年和2016年分别增加了9.95%、8.87%。粗蛋白产量在2016年显著降低，F2T3的粗蛋白产量在2016年较F1T3增加9.29%。亚油酸含量在2015年和2016年显著降低， F1T3的亚油酸含量较F2T3在2015年和2016年分别增加了3.17%和3.03%。施钾时期对油葵的盘径、亚麻酸含量没有显著影响，但对油葵的千粒重、出仁率、产量、蛋白质含量、蛋白质产量、粗脂肪含量、产油量、油酸、亚油酸影响显著。钾肥的最佳施用时期为基施。油葵产量与盘径、千粒重、出仁率均有显著的正相关关系，油酸和亚油酸之间存在负相关关系。