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。将板料划分为四个区域 :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。     

Prediction of flange wrinkling in deep drawing process using bifurcation criterion

Surface distortions in the form of wrinkles are often observed in sheet metals during stamping and other forming operations. Because of the trend in recent years towards thinner, higher-strength sheet metals, wrinkling is increasingly becoming a more common and troublesome mode of failure in sheet metal forming. The prediction and prevention of wrinkling during a sheet forming process are important issues for the design of part geometry and processing parameters. This paper treats the phenomenon of flange wrinkling as a bifurcated solution of the equations governing the deep drawing problem when the flat position of the flange becomes unstable. Hill’s bifurcation criterion is used to predict the onset of flange wrinkling in circular and square cup drawing. In particular, the maximum cup height that can be drawn without the onset of flange wrinkling is predicted for the given set of process parameters. A parametric study of the maximum cup height is also carried out with respect to various geometric, material and process parameters. Finite element formulation, based on the updated Lagrangian approach, is employed for the analysis. The incremental logarithmic strain measure, which allows the use of a large incremental deformation, is used. The stresses are updated in a material frame. The material is assumed to be elastic–plastic, strain hardening, yielding according to an anisotropic yield criterion of Barlat et al. (2005) [23] (named as Yld2004-18p). Isotropic power law hardening is assumed. Inertia forces are neglected due to small accelerations. Modified Newton–Raphson iterative technique is used to solve the nonlinear incremental equations.     

从含钴废料中提取钴的研究进展

叙述了钴资源的分布概况，详细介绍了当前提取钴的方法与技术进展。我国作为钴资源缺乏的国家，提高钴的回收率是非常必要的。     

基于聚类分析和判别分析的河流水质空间分析方法

水质改变受到时间、气候、人为等多方面的因素影响,形成的检测数据也十分复杂而多样,要客观的对其进行分析与监控就需要对其进行分类处理,利用聚类与判别方式将其归类并突出主要因素,这样才能在水质分析中获得较好的效果。     

参数化绘图系统的开发与应用

探讨了参数化绘图系统开发的基本算法、功能和要求及开发步骤,简单介绍了国内外参数化CAD的应用情况。     

Decomposition of poly(amide-imide) film enameled on solid copper wire using atmospheric pressure non-equilibrium plasma

The decomposition of a poly(amide-imide) thin film coated on a solid copper wire was attempted using atmospheric pressure non-equilibrium plasma. The plasma was produced by applying microwave power to an electrically conductive material in a gas mixture of argon, oxygen, and hydrogen. The poly(amide-imide) thin film was easily decomposed by argon-oxygen mixed gas plasma and an oxidized copper surface was obtained. The reduction of the oxidized surface with argon-hydrogen mixed gas plasma rapidly yielded a metallic copper surface. A continuous plasma heat-treatment process using a combination of both the argon-oxygen plasma and argon-hydrogen plasma was found to be suitable for the decomposition of the poly(amide-imide) thin film coated on the solid copper wire.     

不加催化剂和掩蔽剂的微波密封消解法测定CODCr

现行的测定化学需氧量的标准方法存在许多缺点，密封消解法缩短了消解时间，但仍存在汞盐污染。作者对微波密封消解法测定ＣＯＤＣｒ作了进一步研究。结果表明，不加Ａｇ２ＳＯ４作催化剂，也不加ＨｇＳＯ４作氯离子的掩蔽剂，该方法同样可以得到与回流法相近的分析结果。同时还提出应当控制的反应时间、反应体系酸度等操作参数。该方法是一种可供选用的无汞盐化学需氧量快速测定法。     

Treatment of phosphorus waste water using crystallization method

Phosphorus is the restrictive factor of water eutrophication and phosphorus removal is the key point to control this phenomenon. It's also important to recover phosphorus resource from wastewater. Crystallization method was used to treat and recycle high concentration phosphorus wastewater, the selection of organic solvent, influence of volume ratio of organic solvent and wastewater, precipitation time and stirring speed on the production of crystal and its structure was investigated. Experimental results indicate that, with ethanol as extractant, under the condition of volume ratio of ethanol to wastewater being 1.5:1 and stirring speed about 200 r/min, crystal precipitated fast with fine crystal shape and purity, phosphorus removal efficiency more than 85% was obtained.     

An expeditious aqueous Suzuki-Miyaura method for the substituted aryl heterocyclics

Palladium-catalyzed cross-coupling reactions utilizing aryl halides have become a widely used strategy for the formation of new carbon-carbon bonds and in particular for the synthesis of biaryls. The replacement of expensive, toxic, and flammable organic solvents by water is highly desirable for reducing costs and for developing environmentally benign synthetic reactions that facilitate catalyst recycling. Herein, we report an efficient Suzuki-Miyaura cross-coupling reaction using a variety of heterocyclic halides in neat water. Employing air- and moisture-stable palladium-phosphinous acid catalyst [(t-Bu)₂P(OH)]₂PdCl₂(POPd) allows formation of substituted aryl heterocyclics in moderate to high yields. The organic cosolvents are not required. The feasibility of catalyst recycling has also been demonstrated.     

污染土壤修复技术的探讨

污染土壤修复技术目前广泛应用的是生物、换土、固化及淋洗修复技术等,对前3种修复技术在处理污染土壤的效果和过程上进行分析和对比,其结果表明都存在着优缺点.通过对污染土壤淋洗技术的定义及分类的了解和与前3种修复技术的比较,并在此基础上产生了移动式异位淋洗修复技术介绍了它的工艺流程及各机械装置的作用,通过对照原有的污染土壤淋洗修复技术,其表明移动式异位淋洗修复技术具有可移动性、修复效率高等特点,具有很大的工程应用价值.     

算术平均法、百分位数法和滑动平均法空气质量评价对比分析及其揭示的信息

综合采用算术平均法、百分位数法和滑动平均法对空气质量进行评价对比分析,可以更加全面、客观、精细、准确地描述空气质量状况,发现其内在规律,揭示不同城市的问题。对比分析发现,全国169个城市空气质量改善程度用算术均值与百分位数测算存在一定差异,并进一步反映出2017年空气质量改善主要归功于污染较为严重天气的减少,2018年主要归功于空气质量良好及轻度污染天气的增加。169个城市PM_(2. 5)浓度的中位数与算术均值之间具有较好的线性关系且越来越强,反映出重污染天气控制取得成效。各区域和城市百分位数同比变化情况反映了大气污染防治不同阶段的工作重点及成效不同:京津冀及周边"2+26"个城市2017年空气质量改善以降低污染天气为主,2018年以增加优良天气为主;珠三角地区和长三角地区都是以增加空气质量为良的天气为主。3年滑动均值比年均值曲线下降更为平缓,更能准确反映污染治理成效。建议深入研究空气质量信息,采用多种评价方法科学、客观、全面地评价污染治理情况。     

环境信息披露制度研究

环境信息披露分为政府环境信息披露和企业环境信息披露两个层面。政府环境信息披露包括政府在制度性信息与管理信息、生态安全信息等方面的披露．企业环境信息披露内容包括企业强制性披露信息与自愿披露信息、企业生产阶段的信息和其他阶段的信息。笔者在对这些问题进行研究和分析的基础上．进一步对我国环境信息披露内容的控制及实施进行了探讨。     

黄河水质监测的分析方法研究

随着对黄河水的治理工作的逐渐深入,关于黄河水质的监测事业都取得了快速的发展并有着不小的进步,当然仍然存在着一些问题,比如监测的条件较为单一且技术落后、监测的断面也不够多、资料信息缺乏等.随着时代的发展,现有的一些关于水质监测的方法已经不能满足监测的要求,所以本文对于黄河水质监测的分析方法做了一定得研究,希望对于水质监测方面有一定的帮助.     

Simulation model for an EB-PVD coating structure using the level set method

A comprehensive modeling approach to link machine dynamics, deposition, and substrate kinematics in an electron beam physical vapor deposition (EB-PVD) is presented in this paper. The machine dynamics in EB-PVD process are captured by finite element models, resulting in the prediction of evaporation rate and vapor distribution. The deposition process is modeled using the level set method, which is one of the computational techniques for tracking topographic evolution. The proposed simulation model is implemented in Matlab and is compared with experimental results published by other researchers. Results indicate that the proposed simulation model can be used to predict microstructure features such as zigzag and helical columnar shapes. The pitch of a zigzag microstructure can be predicted within 20% at the 0.3 to 6 μm level for Yttira-stabilized Zirconia (YSZ) coating.     

大小兴安岭森林开发对野生动物的影响分析

森林质量下降,火灾、工业发展对林区野生动物的影响分析.     

An analysis of the causes of the mitigation bias in international climate finance

Research on international climate finance got a new impetus from the United Nations Framework Convention on Climate Change Cancun Accords in 2010 which pledge to mobilize US dollars (USD) 100 billion in international climate financing annually by 2020. The Accords’ specification that adaptation must be addressed with the same priority as mitigation is not reflected in current patterns of international climate finance where we face a strong bias towards mitigation finance. A recent study by Buchner et al. (2011) ascertains a split between mitigation and adaptation finance of 95:5. In this paper, we investigate potential reasons for this bias. In our framework, we distinguish different decision layers and actors involved in international climate finance in order to categorize the causes responsible for the low priority of adaptation in international finance. The identification of obstacles for international adaptation funding is a first crucial step in the search for ways to overcome respective barriers. We find several different causes of the mitigation bias and these might offer starting points for policies aiming at raising adaptation finance and curing this bias. Furthermore, we describe interrelations between these causes which effective policies have to take into account.     

固相萃取-高效液相色谱法测定海水中多环芳烃

针对环境中常见且对人体危害极大的USEPA优先控制污染物多环芳烃(PAHs)在海水中的监测方法进行研究.以国家标准分析方法和美国环保局分析方法为基础,采用固相萃取-高效液相色谱法来测定.探讨了各条件对测定的影响,经过固相萃取,七种PAHs在反相高效液相色谱中有很好的分离效果,满意的回收率,方法简便,具有良好的应用前景.