稻油轮作区驱动圆盘犁对置组合式耕整机设计与试验

针对长江中下游稻油轮作区油菜种植时土壤黏重板结、秸秆量大、播种作业需同步开畦沟的农艺要求,考虑传统耕整作业耕层浅、功耗大的不足,依据驱动圆盘犁组与传统铧式犁相比,不易缠草堵塞、通过性好、牵引阻力小的特征,设计了用于油菜播种的驱动圆盘犁对置组合式耕整机。提出了主动式对置犁耕与被动式开畦沟、碎土、平整相结合的联合耕整作业方案,分析了对称布置的圆盘犁组的动力学和运动学特性,确定了其主要结构和工作参数。根据犁体曲面成形原理,设计了开畦沟前犁犁体曲面;依据组合式船型开沟器与土壤挤压互作机制的分析,确定了开畦沟区域宽度为350 mm时,开畦沟系统作业后可有效保证畦沟和种床厢面质量。耕深稳定性试验表明,整机作业实际耕深与限深深度基本一致,耕深稳定性系数均在90%以上。厢面质量试验表明,开畦沟系统在中间开畦沟区域能开出沟宽241.6~293.5 mm,沟深328.6~370.8 mm的梯形沟。经组合式船型开沟器挤压的土壤对犁沟的实际填埋率高于87.67%,碎土辊作业后厢面平整度为22.45~26.70 mm,碎土率为60.14%~68.37%。正交试验结果表明,整机较优工作参数为:限深深度为180 mm,机组前进速度为3.5 km/h,圆盘犁组转速为160 r/min,此时整机功耗为24.37 k W,相比传统旋耕方式的油菜播种种床整备机具的功耗降低了37.67%,秸秆埋覆率为92.78%,碎土率为66.74%,厢面平整度为24.18 mm,土壤对犁沟平均填埋率为92.3%,满足油菜播种的农艺要求。     

Repeated annual drought has minor long‐term influence on δ13C and alkane composition of plant and soil in model grassland and heathland ecosystems

As a result of global climate change the incidence of drought conditions in Europe is predicted to increase in the future, which also influences plant resistance. Lipids are important plant constituents that protect plants against drought stress and contribute to the intermediate stable carbon (C) pool in soil. However, the extent to which drought influences lipid cycling in the plant–soil system is unknown and, therefore, it remains questionable how the ecosystem recovers after drought. We focused on plant and soil samples from two different plant communities (temperate grassland and heathland) that had been exposed to 5 years of 4.5–6.0 weeks repeated annual drought. They were sampled one year after the last drought to check the recovery of the plant–soil system. Samples were analyzed for their bulk C, stable C and nitrogen (N) isotope (δ¹³C, δ¹⁵N) and lipid composition. Contrary to our expectation, no strong influence of five years of repeated annual drought was observed for above‐ground biomass, roots and soils in the model ecosystems with respect to elemental (C and N concentrations, C : N ratio) bulk isotope (δ¹³C, δ¹⁵N) composition and the total extractable lipid concentration. Thus, plants did not sustain a significant change in their C and lipid concentration as well as their composition after five years of repeated annual drought. This might be related to the comparatively short drought period related to the overall growth season and provides evidence for recovery of the C and lipid dynamics in temperate grassland and heathland model ecosystems exposed to annual drought.     

基于流声耦合法的超低比转数离心泵空化特性研究

为研究离心泵不同空化状态下噪声特性的变化规律,以及空化的发展对水动力噪声的影响,首先以一台超低比转数离心泵为研究对象,搭建闭式试验台,基于泵产品测试系统及数据采集系统建立了离心泵空化噪声的试验测试系统,实现了泵性能参数和内场噪声信号的同步采集。其次,分别应用不同空化模型对模型泵空化性能曲线进行预测,并与试验值进行对比,选择合适的空化模型。在此基础上将整个空化过程划分为未空化阶段、空化初生阶段、特征空化阶段及严重空化阶段,结合声学边界元法将流场信息转化为声场信息,并通过比较各空化阶段噪声预测值与试验值相对误差,发现模拟信号与实际信号吻合度较高,充分验证了预测方法的可行性。最后,基于流声耦合法研究空化对内部声场的影响。研究发现:针对超低比转数离心泵空化,Zwart模型比Kunz模型具有更好的适用性。内场噪声信号随空化的发展变化规律比较复杂。在中低频段,由于空化对动静干涉的抑制作用,使得叶频及其倍频特征值离散分量声压级随空化的发展呈现逐渐下降趋势,而轴频分量呈现增大趋势;而高频宽频噪声随空化系数的降低呈现先缓慢减小、然后急剧上升的规律,逐渐将高频特征值分量淹没在宽频带中,高频段声压级的增高造成总声压级的升高。     

望远摄影测树仪设计与试验

以摄影测量学原理、图像处理技术原理、测树学原理为理论基础,设计望远摄影测树仪,该仪器由PDA模块、远程EDM模块、长焦CCD镜头模块和云台组成,测量时获取倾角、方位角、远程距离及图像信息等参数,通过在Android Studio 2.1开发环境下集成并利用Java语言进行汇编实现树高测量、胸径测量、微样地林分测量等功能。通过试验验证,树高测量精度达93.32%,胸径测量精度达96.49%,林分平均高度测量精度达94.47%,林分平均胸径测量精度达91.68%,林分密度测量精度达86.04%,林分蓄积量测量精度达82.64%,解决了不可到达点观测难度高、看得见测不到等问题。     

长期定位施不同氮源有机肥替代部分含氮化肥对陇东旱塬冬小麦产量和水分利用效率的影响

在陇东黄土旱塬覆盖黑垆土大田,利用陇鉴301进行了连续10年的定位试验,观测长期施用不同氮源有机肥(发酵有机肥、农家肥)或小麦秸秆还田各处理对冬小麦产量相关性状和水分利用效率的影响。结果显示,小麦产量和水分利用效率年际间变化较大,与降雨量有直接关系;不同有机氮源替代部分含氮化肥处理对提高冬小麦产量和水分利用效率具有明显作用。在干旱、平水和丰水年型,较不施肥对照分别增产53.1%~103.7%、40.3%~79.3%和73.1%~94.8%,较单施化肥对照分别增产6.6%~41.8%、7.0%~36.8%和-2.9%~9.3%。以发酵有机肥做替代物处理的产量和水分利用效率最高,增产幅度最大,10年平均产量较不施肥和单施化肥对照分别增加88.9%和25.4%,水分利用效率和边际水分利用率也最高,分别为10.8 kg mm~(-1) hm~(-2)和1.03 kg m~(-3);并且产量构成因素和植株生理指标也优于其他处理。因此,发酵有机肥是陇东半湿润偏旱雨养农业区(年降水量约550 mm)冬小麦生产上替代部分含氮化肥的首选有机氮源。     

基于二维激光传感器无人直升机作业边界探测

无人机喷雾作业边界探测识别是无人直升机喷雾的重要内容,如果喷雾最大喷幅超过目标区域,会导致药液流失,造成环境的严重污染。为此,基于无人直升机平台,选取二维激光扫描传感器、姿态传感器等传感器搭建了一套二维激光扫描探测系统。该系统利用二维激光传感器探测无人直升机距离作物冠层和田埂的高度,计算冠层和田埂距离差值,并把高度差值作为分割阈值,实现无人直升机作业边界的提取,同时进行了田间试验验证。     

Diversity of methodologies to experiment Integrated Pest Management in arable cropping systems: Analysis and reflections based on a European network

Integrated Pest Management (IPM) aims to promote physical and biological regulation strategies that help farmers contain populations of pests (pathogens, animal pests and weeds) and to finally reduce the reliance on pesticides. It is based on the holistic combination of multiple management measures rather than on the sum of single methods, each of them having only small effects on pests reduction. Thus, to analyse the interactions between IPM measures and to evaluate the sustainability of their implementation, we require an approach considering the whole cropping system (CS), i.e. a functional entity whose complexity is more than the sum of its parts. A network of European experiments at the CS level was set up recently, and aimed at sharing data and expertise to enhance knowledge of IPM. Comparison of existing methodologies highlighted a diversity of CS designs and experimental layouts. We deduced that the concept of CS itself was viewed differently among scientists, and this affected experimental protocols. Other differences were related to the research context and objectives. Some experiments aimed to explore very innovative strategies and generated knowledge on both their effects on the agroecosystem and their ability to satisfy a set of performance targets, while others aimed to provide quickly adoptable solutions for local farmers in line with the current socio-economic constraints. In some research programmes, the experiment was part of the CS design process — and tested CS were regularly revised based on an continuous improvement loop — while in other cases CS were kept stable across years so as to enable the evaluation of their long-term cumulative effects. A critical aspect contributing to the diversity among CS experiments was the distinction between a factorial design of experimental CS and systemic approaches: factorial experiments allowed quantification of the effects of each IPM component regardless of the consistency between components defining the CS. In contrast, systemic approaches focused on the overall evaluation of CS designed with consideration of their consistency, hence maximising their ability to meet the objectives. Because CS experiments represent a huge investment in terms of economics and time, preliminary reflections of the relevance of the experimental strategy is of critical importance.     

链齿式残膜回收输送方式对比分析与试验

针对传统下输送链齿式残膜回收机存在的捡拾效果不佳与输膜不畅等现象,提出了上输送残膜回收方式,并对两种输送方式的残膜回收机在拾膜和脱膜阶段的机理进行了分析;从理论角度分析了两种输送方式的可行性,并对其特点进行了比较。分别设计了结构参数相同但输送方式不同的两台链齿式残膜回收机,一台采用下输送方式,而另一台采用上输送方式。在收获后的花生田进行收膜对比试验,对影响机具作业质量的输送方式、输送链转速和脱膜辊转速3个主要因素进行正交试验,结果表明:输送方式是影响机具捡拾率的主要因素,上输送方式的捡拾率达到91.9%,远高于下输送方式,综合作业质量上输送方式优于下输送方式。该对比试验可为链齿式残膜回收机输送方式的选择和未来的研发方向提供参考。     

不同药剂防治水稻高龄稻纵卷叶螟试验初报

667m2用15.00%安打SC16mL和3.00%阿维菌素EC100mL处理,对水稻高龄纵卷叶螟杀虫效果最好,其防效在97.00%以上。     

综合设计性实验在食品微生物实验中的应用探讨

随着人们对食品营养与安全问题重视程度的提高,高校对食品微生物实验教学质量提出了更高要求,而综合设计性实验为这种高要求提供了实现平台。探讨了综合设计性实验在食品微生物实验教学中应用的必要性,分析了综合设计性实验实施过程中体现的优势和出现的问题,并提出相应的解决方案,为综合设计性实验的广泛开展提供一定借鉴。