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提出了一种联合上限法(Upper Bound Method)和主应力法(Slab Method)确定模具与金属接触表面压力分布的方法.这是一种基于利用上限法确定金属流动和变形区,然后根据主应力法原理计算接触面压力分布的方法,简称UBM/SM联合法.这种方法较其它方法简便,而且能给出计算压力分布的解析式.本文阐述该法的基本原理,并用它计算杯形件反挤时凸凹模表面的压力分布. 相似文献
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本文根据前文所提联合上限法和主应力法确定模具表面压力分布的基础原理,计算了圆柱坯料正挤压和十字头锻件镦挤时模具表面的压力分布,所得结果与测定值很吻合,进一步证明了UBM/SM法实际应用的可靠性. 相似文献
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以上海市某冶金企业为例,该厂有正常运行的冶炼炉13座,每年向大气中排放大量颗粒污染物.基于高斯倾斜烟羽模式,整理了2003年上海市全年的气象资料,运用气象概率矩阵法计算了该厂直排点源及无组织面源排放颗粒物的影响,得出了厂区内无组织排放颗粒物落地浓度等值线图.计算结果表明,厂区内颗粒物污染主要来自无组织面源,污染集中在厂区中心的污染源附近;直排点源对环境的影响较小,污染主要集中在下风向. 相似文献
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A.D. Bhanarkar S.K. Goyal R. Sivacoumar C.V. Chalapati Rao 《Atmospheric environment (Oxford, England : 1994)》2005,39(40):7745-7760
Contribution of pollution from different types of sources in Jamshedpur, the steel city of India, has been estimated in winter 1993 using two approaches in order to delineate and prioritize air quality management strategies for the development of region in an environmental friendly manner. The first approach mainly aims at preparation of a comprehensive emission inventory and estimation of spatial distribution of pollution loads in terms of SO2 and NO2 from different types of industrial, domestic and vehicular sources in the region. The results indicate that industrial sources account for 77% and 68% of the total emissions of SO2 and NO2, respectively, in the region, whereas vehicular emissions contributed to about 28% of the total NO2 emissions. In the second approach, contribution of these sources to ambient air quality levels to which the people are exposed to, was assessed through air pollution dispersion modelling. Ambient concentration levels of SO2 and NO2 have been predicted in winter season using the ISCST3 model. The analysis indicates that emissions from industrial sources are responsible for more than 50% of the total SO2 and NO2 concentration levels. Vehicular activities contributed to about 40% of NO2 pollution and domestic fuel combustion contributed to about 38% of SO2 pollution. Predicted 24-h concentrations were compared with measured concentrations at 11 ambient air monitoring stations and good agreement was noted between the two values. In-depth zone-wise analysis of the above indicates that for effective air quality management, industrial source emissions should be given highest priority, followed by vehicular and domestic sources in Jamshedpur region. 相似文献
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John?YangEmail author Jianguo?Sun David?Hammer Robert?Blanchar 《Environmental Chemistry Letters》2004,2(3):159-162
Soil pH, a log-transformed form of hydrogen ion (H+) activity, is often used for various statistics. However whether soil pH meets the requirement of distribution normality for statistical analyses is unknown. We studied the statistical suitability of both soil pH and H+ activity by examining their distribution normalities. Results show that the variability of H+ activity is higher and its distribution is skewer, which is significantly different from the normal and soil pH, regardless of soil conditions and analytical methods. Here we demonstrate that soil pH is more appropriate than the H+ activity for performing statistical analysis in terms of distribution normality. 相似文献
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A methodology for simulating climate change impacts on tree growth was introduced into a statistical growth and yield model in relation to variations in site fertility and location implemented with current temperature sum. This was based on a procedure in which the relative enhancement in stem volume growth was calculated from short-term runs of a physiological simulation model for Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies (L.) Karst.) and silver birch (Betula pendula Roth.) stands. These simulations were made for a set of stands with species-specific variations in stand characteristics, location and fertility type first in current climatic conditions and then in different combinations of CO2 and temperature elevations. Based on these simulations, the relative enhancement of volume growth induced by the climate change (relative scenario effect, RSEv) was calculated and modelled in relation to: (i) CO2 and temperature elevation, stand density and the competition status of the tree in its stand, and (ii) variations in site fertility type and current temperature sum of a stand. Finally, these transfer functions for RSEv were applied to adapt the stem volume growth in the statistical growth and yield model to reflect the response to climate change. 相似文献