电热管焊接接头挤压裂纹的分析

针对电热管焊接接头挤压产生的裂纹 ,通过采用金相显微镜观察其金相组织并用直读光谱对原材料成分进行化学成分分析 ,排除了成分、焊接工艺规范等的影响。经过对挤压过程分析 ,发现应力集中点是产生裂纹的主要原因 ,并提出了改进的方法     

Trace element speciation in selected smelter-contaminated soils in Anaconda and Deer Lodge Valley, Montana, USA

Long-term copper smelting in the Anaconda and Deer Lodge Valley area of Montana has resulted in an extensive area of trace element contamination. Aerial extent of contamination is generally established, but total analysis of soils does not correlate to relative degree of impact on vegetation growth. Three pedons (Beaverell, Cetrack and Judco) were analyzed by routine soil characterization methods, aqua regia microwave digestion, sequential chemical extraction, and X-ray diffraction analysis with the objective of providing a better understanding of chemical forms and potential reactivity of selected trace elements (Cd, Co, Cr, Cu, Hg, Mn, Ni, P, Pb). Surface horizons of soils are more acidic than subsoils, with pH for all horizons ranging from 4.0 to 8.7. Beaverell is the most contaminated in the upper 20 cm with the sum of total extractable (SUM_TE) trace elements by microwave digestion ranging from 1836 to 3605 mg kg⁻¹, largest H₂O-soluble (WS) and exchangeable (EX) fractions (e.g. 1.6 and 9.3%, respectively), and smallest residual (RES) fraction (e.g. 14.3%). Cetrack has greater SUM_TE elements than Judco, though a lower WS+EX fraction due to the effects of alkaline pH, carbonates and high P. Oxide (OX), organic matter/sulfide (OM/S), and RES fractions predominate over WS, EX, and specially-sorbed/carbonate-bound fractions (SS/CAR) for all horizons. Copper, Zn, Pb and Cd are elevated in surface over subsurface horizons in these latter fractions, indicating these elements were anthropogenic additions. X-ray data indicate that Pb, Cu, Cr and Cd partially exists as both OX and sulfide mineral forms.     

半球形封头热拉深成形理论分析

利用主应力法对半球形封头的拉深成形进行了分析与研究。将板料划分为 4个区域 :法兰区、凹模圆角区、悬空锥形区和球形区 ,对每个区域的应力分布进行了理论推导与探讨 ,以期对该类产品的设计、生产和加工有所帮助     

虎克定律在高精度翻孔模设计中的应用与实践

以汽车摇摆臂为应用对象 ,通过对材料在翻孔过程中变形的理论分析和实际运用 ,探讨了虎克定律在高精度翻孔模设计中的应用与实践     

陕西铜厂矿田控矿断裂带显微构造特征

本文在研究铜厂矿田地质特征和宏观断裂构造带特征的基础上 ,对矿田内不同类型断裂构造岩进行了分类和显微结构面力学性质的鉴定 ,研究了岩石和矿物的形变与相变 ,探讨了微观领域内的动力成岩成矿作用 ,并分别估算和厘定了古应力的大小和方向 ,为再现矿田构造应力场奠定了基础。     

大直径桩端阻力面积修正系数研究

桩端阻力和桩端直径呈非线性关系,随着桩端直径的增加而逐渐减小。本文根据线弹性理论和非线性弹性理论分别求得大直径灌注桩桩端阻力的面积修正系数的上限解和下限解,得到了桩端土承载力标准值与桩端直径的非线性关系和桩端土承载力面积修正系数与桩端直径的非线性关系。与现行建筑桩基技术规范相比,当桩径 0．80～3．00 m时,规范给定的面积修正系数稍大于理论上限值,其它桩径范围的桩端面积修正系数均在理论值的上、下限范围。当桩径0．80～2．00 m时,按规范给定的面积修正系数修正后的承载力标准值稍大于理论上限值, 其它桩径范围按规范修正后的桩端土承载力标准值均在理论值的上、下限范围。     

牛赶冲矿段地质构造研究及其意义

本文主要对洋水磷矿区牛赶冲矿段下盘矿的断裂和褶皱构造的产状、形态、位置、对矿体的破坏程度及其形成机制等进行了综合研究,并对研究结果在矿山生产实践中的指导意义进行了阐述。     

水泥土桩复合地基桩土应力参数研究

本文首先通过理论分析，认为桩土应力比、桩土荷载分担比等是反映水泥土桩复合地基工作性状的重要参数。然后通过现场试验，研究桩土应力比、桩土荷载分担比随荷载变化的规律。结果认为：随着荷载增加，桩土应力比逐渐减小，当比值达到某一特征值后，不再发生明显变化；桩土应力比、桩土荷载分担比不为常数，其变化是桩土变形协调的结果。最后得出有一定参考价值的结论。     

A Conceptual Framework for Selecting and Analyzing Stressor Data to Study Species Richness at Large Spatial Scales

/ In this paper we develop a conceptual framework for selectingstressor data and analyzing their relationship to geographic patterns ofspecies richness at large spatial scales. Aspects of climate and topography,which are not stressors per se, have been most strongly linked withgeographic patterns of species richness at large spatial scales (e.g.,continental to global scales). The adverse impact of stressors (e.g., habitatloss, pollution) on species has been demonstrated primarily on much smallerspatial scales. To date, there has been a lack of conceptual developmenton how to use stressor data to study geographic patterns of speciesrichness at large spatial scales.The framework we developed includes four components: (1) clarification of theterms stress and stressor and categorization of factors affecting speciesrichness into three groups-anthropogenic stressors, natural stressors, andnatural covariates; (2) synthesis of the existing hypotheses for explaininggeographic patterns of species richness to identify the scales over whichstressors and natural covariates influence species richness and to providesupporting evidence for these relationships through review of previousstudies; (3) identification of three criteria for selection of stressor andcovariate data sets: (a) inclusion of data sets from each of the threecategories identified in item 1, (b) inclusion of data sets representingdifferent aspects of each category, and (c) to the extent possible, analysisof data quality; and (4) identification of two approaches for examiningscale-dependent relationships among stressors, covariates, and patterns ofspecies richness-scaling-up and regression-tree analyses.Based on this framework, we propose 10 data sets as a minimum data base forexamining the effects of stressors and covariates on species richness atlarge spatial scales. These data sets include land cover, roads, wetlands(numbers and loss), exotic species, livestock grazing, surface water pH,pesticide application, climate (and weather), topography, and streams.KEY WORDS: Anthropogenic impacts; Biodiversity; Environmental gradients;Geographic information systems; Hierarchy     

特大型煤和瓦斯突出的地质条件及其成因

特大型煤和瓦斯突出危害极大，具有独特的发生条件，应专门研究。在全国９９ 次特大型煤和瓦斯突出详细研究的基础上，总结了特大型突出的一般特征及发生的地质和采矿条件，并给出了南桐矿区的几个临界值。对特大型突出地质条件的成因进行了较深入的探讨，提出了防止特大型突出的几点建议