Commercial pole production in linear agroforestry systems

While the stems of upperstorey trees in agroforestry systems have many uses such as firewood and fencing, it remains true that one incentive for growing upperstorey trees is the anticipated income generated by selling commercial quality poles. Three hundred and ninety-one poles representing 15 tree species grown under linear agroforestry conditions at four sites in Uganda were analyzed in terms of the length, diameter and taper of their poles. At the time of harvest, the trees were 41 months old. Although the poles varied in size and shape, none conformed to the standards observed in the commercial pole market in Kampala. The results demonstrate that linear agroforestry systems are unlikely to produce high quality commercial poles in a short time although they have other uses. Development of commercial pole production in these systems requires low cost management practices. New research designs and hypotheses are needed to assess the potential of commercial pole production. They must consider trials with larger plots, longer duration and varying management practices such as side pruning, spacing, coppicing and pollarding.     

转子流量计的安装及提高测量精度的探讨

通过对转子流量计的安装注意事项、使用特点及测量精度方面的论述,为此类设备的安装使用和运行管理工作提供了有益的经验。     

Alley cropping Sesbania sesban (L) Merill with food crops in the highland region of Rwanda

Food production in the densely populated Rwandan highlands is impeded by soil erosion and loss in fertility. Alley cropping leguminous shrubs with food crops on contours is purported to minimize the problem and to provide wood and forage. This study reports the effect of Sesbania prunings plus moderate levels of N and P on bean (Phaseolus sp) and maize (Zea mays) yields in alley cropping. Experimental design was a randomized complete block with split-split plots. Main plots were alley width: 2, 4, 6 and 8 m. Phosphorus (P) at 0, 30 and 60 kg P₂O₅/ha occupied the subplot and nitrogen (N) at 0, 30 and 60 kg/ha were assigned at the sub-sub plot level. No P was applied to maize during the second cropping season. Crop yield in kg/ha included the land space taken by hedgerows. Bean yield in 6 m alleys (1100 kg/ha) was about twice that in 2 m alleys (500 kg/ha). Bean responded to N and P. Optimum alley width and N for bean yield were 6 m and 30 kg/ha, respectively. Cuttings from alley hedgerows provided stakes for climbing beans. Maize responded to N but not to residual P. The highest maize yield came from 8 m alleys with 40 kg/ha, but yields from 8 and 6 m alleys with the same N treatment were not significantly different. Maize plants in middle rows were significantly taller than plants in rows adjacent to hedgerows. Maize rust development showed significant alley width and row position effect. There were significantly fewer uredinia in the Sebania alleys relative to the control plots without shrub hedgerows. Rust development on maize in middle rows was significantly greater than development in border rows.     

山区架空电力线路的路径选择和杆塔定位

架空电力线路的路径选择是线路建设中的一个重要部分，直接影响到线路建设的经济性、安全可靠性和施工维护。本文就如何进行正确的线路路径选择提出了具体的原则，同时结合大兴安岭地区山区的特点，提出了如何进行适当的电力线路的杆塔定位的方法，从而提高线路建设的经济性和运行安全可靠性。     

异形柱的正截面承载力计算方法

本文主要介绍了钢筋混凝土框架结构中异形柱正截面承载力的计算方法和适用范围。     

应力应变监控技术在管道桁架跨越中的应用

大跨度管道桁架跨越多采用牵引（顶推）方法施工,但施工荷载和外界因素导致桁架杆件产生复杂的应力状态,因而过程控制对整个施工成败具有关键作用。以境外某管道桁架跨越工程为例,从桥路选择、数据采集系统、施工过程数值模拟计算、传感器选择与安装等方面详细论述了应力应变监控技术在该工程中的应用。监控结果显示桁架最大应力为121 MPa,经现场及时调整牵引速度后,桁架应力稳定在90 MPa以内,与计算值基本吻合。应力应变监控技术能够及时、准确地提供关键结构部位的受力情况,具有较强的可实施性,可以有效保障工程施工的安全。     

防坠安全器在油库接卸油作业中的应用

梳理了石油销售行业中油库接卸油作业环节易发生高空坠落事故的原因,介绍了速差防坠安全器的工作原理、性能特点、适用范围、安装步骤以及使用过程中的注意事项,同时从个别部件的材质选择、防坠器和安全带等产品的选购、防坠器的安装位置及其与铁路栈桥和付油罩棚进行一体化设计等方面提出了具体建议。速差防坠安全器具有结构轻巧、安装简便、操作简单、方便实用的特点,在油库接卸油高空作业环节中正确安装、使用防坠安全器,可以有效预防接卸油过程中高空坠落事故的发生,保障作业人员的安全。     

浅谈山东潍坊华奥钢铁集团汽轮机安装工程的试运行

汽轮机试运行是华奥钢铁集团汽轮机安装工程的一个重要环节,也是对整个安装过程的验收,是确保汽轮机组正常运行的保障。     

阜新市设施农业及其装备发展探析

发展设施农业是推进农业现代化的重要内容,也是调整农业产业结构、实现农民持续增收的有效途径。结合阜新市开展设施农业建设的实际情况,简要分析设施农业及其装备的发展现状、存在的主要问题,提出发展设施农业应采取的对策,为提高我国的设施农业整体水平提供理论依据。     

浅谈建筑电气施工安装技术

随着建筑电气工程质量水平的提高,电气的施工工艺水平也逐渐得到提升,安全、节能施工理念始终贯穿于建筑电气安装施工全过程中。文章建筑电气安装施工的准备工作入手,针对各环节的安装技术进行了详细的阐述。