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91.
92.
汽车上将蓄电池负极与车身的金属部分相连接的导线通常称为搭铁线。搭铁线虽小,在汽车电路中却起着重要的作用。着重介绍了汽车搭铁线的类型、作用、故障诊断,为正确检修提供参考。 相似文献
93.
P.B. Irénikatché Akponikpè Koffi WimaHamma Yacouba André Mermoud 《Agricultural Water Management》2011,98(5):834-840
The scarcity of freshwater resources is a critical problem in semi-arid zones and marginal quality water is increasingly being used in agriculture. This paper aimed at evaluating the physico-chemical and biological risks on irrigated soils and fruits of macrophyte treated wastewater (TWW), the nutrients supply, and the effect on tomato and eggplant production in semi-arid Burkina Faso. During three years of experiments, treated wastewater was used, with fresh water as control, in combination with or without mineral fertilizer application at recommended rate (140 kg N/ha + 180 kg P2O5/ha + 180 kg K2O/ha). The study revealed that the treated wastewater provided variable nutrients supply depending on year and element. The treated wastewater without mineral fertilizer improved eggplant yield (40% in average) compared to the freshwater. Both crops responded better to mineral fertilizer (52% for tomato and 82% for eggplant) and the effects of the treated wastewater and fertilizer were additive. As the N supply of TWW was very unsteady (8-227% of crop need), and P2O5 supply did not satisfy in whole crop need (3-58%) during any of the three years of experiment, we recommended that moderate N and P2O5 fertilizers be applied when irrigating with TWW in semi-arid West-Africa. On the contrary, the K2O supply was more steady and close to crop requirement (78-126%) over the three years of experiment and no addition of K fertilizer may be needed when irrigated with TWW. Faecal coliforms and helminth eggs were observed in treated wastewater and irrigated soils at rate over the FAO and WHO recommended limits for vegetable to be eaten uncooked. Tomato fruits were observed to be faecal coliform contaminated with the direct on-foliage irrigation with treated wastewater. Our results indicate that treated wastewater can effectively be used as both nutrients source and crop water supply in market gardening in the semi-arid Sub-Saharan West Africa (SSWA) where freshwater and farm income are limiting. Yet consumers should properly cook or disinfect treated-wastewater irrigated vegetables before eating, and market gardeners should also be careful manipulating treated wastewater to avoid direct health contamination in this environment. 相似文献
94.
Elin Enfors Jennie Barron Hodson MakuriraJohan Rockström Siza Tumbo 《Agricultural Water Management》2011,98(11):1687-1695
Yield levels in smallholder farming systems in semi-arid sub-Saharan Africa are generally low. Water shortage in the root zone during critical crop development stages is a fundamental constraining factor. While there is ample evidence to show that conservation tillage can promote soil health, it has recently been suggested that the main benefit in semi-arid farming systems may in fact be an in situ water harvesting effect. In this paper we present the result from an on-farm conservation tillage experiment (combining ripping with mulch and manure application) that was carried out in North Eastern Tanzania from 2005 to 2008. Special attention was given to the effects of the tested treatment on the capacity of the soil to retain moisture. The tested conservation treatment only had a clear yield increasing effect during one of the six experimental seasons (maize grain yields increased by 41%, and biomass by 65%), and this was a season that received exceptional amounts of rainfall (549 mm). While the other seasons provided mixed results, there seemed to be an increasing yield gap between the conservation tillage treatment and the control towards the end of the experiment, and cumulatively the yield increased with 17%. Regarding soil system changes, small but significant effects on chemical and microbiological properties, but not on physical properties, were observed. This raises questions about the suggested water harvesting effect and its potential to contribute to stabilized yield levels under semi-arid conditions. We conclude that, at least in a shorter time perspective, the tested type of conservation tillage seems to boost productivity during already good seasons, rather than stabilize harvests during poor rainfall seasons. Highlighting the challenges involved in upgrading these farming systems, we discuss the potential contribution of conservation tillage towards improved water availability in the crop root zone in a longer term perspective. 相似文献
95.
加强运行的TV在线诊断及监视,十分必要,发现TV异常现象,立即进行分析,可以发现故障,进行检修,可以减少电网及设备事故,确保电网安全运行.文章介绍了电压互感器分类、原理,电压互感器常见的故障种类,怎样加强电压互感器运行巡视,在线诊断、故障处理及分析方法. 相似文献
96.
文章主要从水电站的实际情况出发,对水电站机电设备状态监测和故障诊断的意义、定义和特点进行了描述,并对现有的设备故障诊断技术的研究及应用现状进行了分析,同时指出了未来水电机组故障诊断技术中应研究的重点方向. 相似文献
97.
基于量子神经网络的马铃薯早疫病诊断模型 总被引:3,自引:0,他引:3
针对马铃薯早疫病智能诊断,将量子计算的态叠加方法和神经网络计算的自适应性结合,提出了将量子神经网络作为马铃薯早疫病诊断模型.该模型隐含层采用多个量子能级的激励函数叠加的量子神经元,有效地解决了病害诊断中模糊决策,在给出的学习算法的训练过程中自适应地确定样本特征数据中的不确定性.此算法能够较好地避免传统神经网络在训练过程中易出现局部极小值的弊端,提高了网络学习速度.仿真结果表明:量子神经网络在马铃薯早疫病诊断中,诊断正确率达到96.5%. 相似文献
98.
99.
模糊故障诊断在水电机组中的应用 总被引:2,自引:0,他引:2
根据水轮发电机组的振动特点,本文探讨了适合于水轮发电机组的振动故障诊断方法,提出了将模糊技术应用于水轮发电机组振动故障诊断的思想,简要阐述了模糊故障诊断的基本原理,列出了水轮发电机组的征兆集和故障集,并根据征兆集和故障集的相互关系,提出了相应的模糊关系矩阵。最后通过模糊关系矩阵的运算,确定水轮发电机组的故障模糊向量。并以实际机组的振动故障为实例,验证模糊故障诊断方法的可行性和优越性。 相似文献
100.