主变压器箱体涡流发热分析及处理

通过110 kV雨润变电站1号主变本体油箱涡流发热问题分析,由主变压器油色谱单氢超标,进而吊罩检查发现,变压器铁心上部水锈及铁心叠片松散问题,最终经紧固铁心叠片和真空热油循环,处理了该缺陷,取得良好效果。     

φ4000mm大型管板带极堆焊技术

通过对大直径20MnMo锻件管板埋弧带极堆焊309LMo的焊接及生产应用的研究,合理选择过渡层焊接材料及堆焊各层的工艺规范参数,减小堆焊层合金元素稀释率,控制铁素体含量,保证了堆焊质量,解决了管板堆焊变形的问题,成功用于产品制造。     

对称割线放张法在庙沟中桥先张法预应力板施工中的应用

对称割线放张法在公路桥梁建设中应用非常广泛，本文通过对对称割线放张法在庙沟中桥建设的应用介绍，简单阐述了对称割线放张法的构思及放张步骤、放张计算及放张方案等方面的介绍，供同行参考。     

Relationship between vegetation of the levee neo‐ecosystems and environmental heterogeneity in the Lower Delta of the Paraná River,Argentina

The relationship between environmental heterogeneity and the vegetation of the levee neo‐ecosystems in the Delta of the Paraná River was studied. These habitat types were considered plant communities of recent origin related to local productive activities. Vegetation coverage was evaluated in 97 plots of three different environmental units (A, B and C), using classification analysis, indirect and direct ordinations. The differential vegetation in different environmental units could be related to a greater fluvial influence of the Paraná River on unit A and a greater tidal influence of the de la Plata River on units B and C. The Lower Delta hydrological regimes only affect a few of edaphic variables particularly pH, organic matter percentage and clay content. To understand the spatial pattern of neo‐ecosystems vegetation, it is also necessary to consider the invasion of alien species that has been taking place for over 50 years.     

Numerical and experimental study on nugget formation in resistance spot welding for three pieces of high strength steel sheets

A resistance spot welding for three pieces of high strength steel sheets was selected as a research subject and the nugget formation processes at the various welding conditions were investigated by both experimental measurement and FEM simulation. The FEM program developed by the authors considered the coupling of the electrical field, thermal field and mechanical field. The interface elements were used to model the transient contact states between two worksheets or between a worksheet and an electrode. The electrical resistance and thermal–mechanical properties of the interface elements change with the contact state, and can have different values from the worksheets and electrodes. The nugget sizes and its formation process predicted by FEM agreed very well with experimental results. The welding conditions (current, cycles and force) to produce sound nuggets for both two pieces and three pieces of high strength steel sheets were accurately estimated by the simulation.     

Conflicts between Perception and Reality in the Management of Alien Species in Forest Ecosystems: A Norwegian Case Study

The vegetation dynamics and landscape management during 20 years of a temperate deciduous forest protected as a nature reserve in western Norway are analysed. Sycamore (Acer pseudoplatanus), an alien species in northern Europe, has become abundant in parts of the forest and the paper discusses how nature management has formulated and interpreted the introduction of sycamore. Scientists and nature managers regard the species as aggressive and a threat to the local natural biodiversity, but in this respect empirical evidence has been replaced by assumption and prejudice, and this is critically reviewed in the paper. The development of the forest has been monitored annually since 1988 and the long-term forest dynamics and behaviour of sycamore are discussed in relation to the attitudes of nature managers. The views held by nature managers are based on their own values and ideas regarding what is valuable nature, and alien species are often assumed to be invasive and aggressive, yet with no reference being made to site ecology and human local history. As an alternative to an a priori understanding of the role of alien species, the paper suggests that proper knowledge of ecosystem dynamics can only be achieved through analysis of ecological variation in space and time. The management of any species should not be according to its status as native or alien, but according to a judgment of its role and long-term behaviour. The values of nature conservationists should not be confused with the intrinsic values of nature.     

连铸坯三段矫直力学行为研究

基于三段矫直曲线应变速率的假设,通过计算三段矫直曲线的精确解,验证了使用小变形条件的正确性;考虑高温铸坯蠕变性能,对铸坯的力学行为进行了分析,得出了使用三段矫直曲线方法,铸坯应变速率、应力及应变在矫直区内变化较为平缓,可有效避免铸坯内裂纹的形成;使用本文三段矫直曲线精确解,调整辊列位置,可进行连铸机的在线技术改造。     

接线片多工位级进模设计

分析了接线片零件的成形工艺，详细介绍了排样设计、工艺计算、模具结构设计、以及一些常见问题的处理方法。     

贝雷抱箍组合在独柱式小体积盖梁中的应用

基于福建省靖海高速公路A1合同段K5+050车行天桥盖梁施工中贝雷片、保险抱箍组合工艺的应用,通过流程阐述及受力分析,表明此方案在独柱式小体积盖梁施工中操作快捷、安全可行。     

套筒致裂法检测混凝土强度应用于地面结构的探讨

介绍了一种矿山地下结构及围岩应力的测试方法－套筒致裂法，阐述了这种方法的原理和测试手段，探讨了把该方法应用于地面结构中检测混凝土强度的理论依据。