覆盖对红叶石楠和红豆杉生长的影响

在相同地域条件下,采用传统养护方式与覆盖养护方式的对比试验,研究覆盖对红叶石楠和红豆杉生长的影响。结果表明:合理有效的覆盖养护方式,可以明显的改良土壤肥力,促进植株生长。     

K步稳定的鞋印花纹图像自动聚类

目的 鞋印是刑事侦查的重要物证之一,如何对积累的大量鞋印花纹图像进行自动归类管理是刑事技术迫切需要解决的问题之一。与其他类图像不同,鞋印花纹图像具有种类多但数目未知、同类花纹分布不均匀且同类花纹数目少的特点。基于鞋印花纹图像的这些特点,用目前典型的聚类算法对鞋印花纹图像集进行聚类,并不能取得很好的效果。在对鞋印花纹图像进行分析的基础上,提出一种K步稳定的鞋印花纹图像自动聚类算法。方法 对已标记的鞋印花纹图像进行统计发现,各类鞋印花纹之间在特征空间上存在互不相交的区域(本文称为隔离带)。算法的核心思想是寻找各类鞋印花纹之间的隔离带,来将各类分开。过程为:以单调递增或递减的方式调整特征空间中判定两点为一类的阈值,得到数据集的多次划分;若在连续K次划分的过程中,某一类的成员不发生变化,则说明这K次调整是在隔离带中进行的,即聚出一类,并从数据集中删除已标记的数据;选择下一个阈值对剩余的数据集进行划分,输出K步不变的类;依此类推,直到剩余数据集为空,聚类完成。结果 在两类公开测试数据集和实际鞋印花纹数据集上进行实验,本文算法的主要性能指标都超过典型算法,其中在包含5792枚实际鞋印花纹数据集上的聚类准确率和F-Measure值分别达到了99.68%和95.99%。结论 针对鞋印花纹图像特点,提出了一种通过寻找各类之间的隔离带进行自动聚类的算法,并在实际应用中取得了很好的效果。且算法性能受参数的变化以及类的形状影响较小。本文算法同样适用于具有类似特点的其他数据集的自动聚类。     

几种修剪树型对'珍珠'番石榴开花坐果及产量的影响

选用4年生'珍珠'番石榴为试脸材料,采用开心形、圆头形、平头形树型结构,以果树生产中采用的自然圆形树型结构为对照,研究4种树型修剪方法对'珍珠'番石榴新梢数、花蕾数、开花结果数及果实产量的影响.试验结果表明,'珍珠'番石榴树型圆头形、开心形促进开花坐果较好,圆头形有利于提高产量.     

改装机械加工设备解决化工装置检修问题研究

随着我国经济水平不断提高，化工设备检修手段也在不断发展，以改装机械加工设备来解决化工装置检修问题成为了当下提高检修效率的热议话题之一。文章主要分析化工装置检修，阐述了以改装机械加工设备方式解决化工装置检修难题的过程，总结经验以供参考。     

Energy use and greenhouse gas emissions from turf management of two Swedish golf courses

Turf management on golf courses entails frequent maintenance activities, such as mowing, irrigation and fertilisation, and relies on purchased inputs for optimal performance and aesthetic quality. Using life cycle assessment (LCA) methodology, this study evaluated energy use and greenhouse gas (GHG) emissions from management of two Swedish golf courses, divided into green, tee, fairway and rough, and identified options for improved management. Energy use and GHG emissions per unit area were highest for greens, followed by tees, fairways and roughs. However, when considering the entire golf course, both energy use and GHG emissions were mainly related to fairway and rough maintenance due to their larger area. Emissions of GHG for the two golf courses were 1.0 and 1.6 Mg CO₂e ha⁻¹ year⁻¹ as an area-weighted average, while the energy use was 14 and 19 GJ ha⁻¹ year⁻¹. Mowing was the most energy-consuming activity, contributing 21 and 27% of the primary energy use for the two golf courses. In addition, irrigation and manufacturing of mineral fertiliser and machinery resulted in considerable energy use. Mowing and emissions associated with fertilisation (manufacturing of N fertiliser and soil emissions of N₂O occurring after application) contributed most to GHG emissions. Including the estimated mean annual soil C sequestration rate for fairway and rough in the assessment considerably reduced the carbon footprint for fairway and turned the rough into a sink for GHG. Emissions of N₂O from decomposition of grass clippings may be a potential hotspot for GHG emissions, but the high spatial and temporal variability of values reported in the literature makes it difficult to estimate these emissions for specific management regimes. Lowering the application rate of N mineral fertiliser, particularly on fairways, should be a high priority for golf courses trying to reduce their carbon footprint. However, measures must be adapted to the prevailing conditions at the specific golf course and the requirements set by golfers.     

试验条件对标准橡胶塑性初值和保持率的影响与分析

通过测试不同厚度的试样和改变相同厚度试样的老化时间及温度来验证和分析试样厚度对塑性初值（P0）、老化条件对塑性保持率（PRI）的影响。试验表明,在其它试验条件不变的情况下,试样厚度偏大塑性初值（P0）也相应偏大,老化时间越长和老化温度越高,老化后的P30和塑性保持率（PRI）就越小。     

运材汽车蓄电池的使用和保养

介绍了运材汽车蓄电池的使用特点和保养方法。     

论园林绿化养护管理研究分析

园林绿化工作的众多环节中,养护管理起着关键性作用,它使此项工作很好并且持续的展现在人们眼前,笔者主要针对当前园林绿化养护滞后原因,进行分析并提出有效建议,希望对后期园林绿化工作有所帮助。     

Influence of four soil maintenance practices on Collembola communities in a Mediterranean vineyard

We studied the influence of four soil maintenance practices on Collembola communities in the soil of a Mediterranean vineyard: (a) postemergence herbicide with glyphosate; (b) postemergence and pre-emergence herbicides with glyphosate, terbuthylazine, diuron and oryzalin; (c) natural flora and (d) tillage to a depth of 10–15 cm. Total Collembola abundance, species diversity and species richness significantly varied between the four practices. Notably, the practice using postemergence and pre-emergence herbicides had significantly lower values. Identification of Collembola at species level allowed an interspecies comparison and revealed significant differences for the most common species between the four practices, with each practice being characterized by a different set of species. None of the species were found to be significantly more abundant in the plots treated with postemergence and pre-emergence herbicides.     

前桥摆转转向式四驱底盘结构形状指数的优化

前桥摆转转向式四驱底盘可直接转入下一畦作业,提高了小地块工作行程率,在地头宽度小于等于1个作业宽度时,更有利于机耕过程中的转向操作。为此,通过ADAMS软件仿真,以最小地头宽度为目标对底盘结构参数进行了优化。仿真结果表明,底盘在作业过程中从一畦进入地头直接转入相邻的下一畦时,后内侧轮基本上不吃入上一畦,最小地头宽度与长宽比成反比。在底盘转向时行走轮不干涉后悬挂农具的前提下,底盘最小的理论长宽比应为0.5:1。但由于底盘长宽比受行走轮直径、轮宽及重心的影响,底盘的合理长宽比值范围需趋近于理论长宽比。当机具作业宽幅大于等于机具轮宽时,可直接做倒U形转向;否则采用"4"和歪梨形组合掉头转向,实现地头宽度等于1个作业幅宽的转向。