Use of Warranties on Highway Projects: A Real Option Perspective

Since the introduction of warranty provisions in federal highway jobs, more and more state departments of transportation (DOTs) have considered the use of such provisions to protect their initial investment. This paper describes the pros and cons of warranty contracting in highway construction based on a survey of warranty practices in the United States. In particular, the need for state DOTs to buy a warranty for a well-built project is questioned. As an alternative, this paper introduces the warranty option, which gives the DOT the right to buy a warranty only if it becomes necessary at the end of construction. This option is exercised if the performance on site warrants it. This paper describes the mechanics of the warranty option and its advantages over the conventional warranty. A bid evaluation model is also developed for the warranty option approach.     

环氧乙烷合成乙二醇的研究进展

介绍了环氧乙烷合成乙二醇的主要生产方法，包括以壳牌、联碳化学公司以及Halcon—SD公司为代表的环氧乙烷直接水合法，环氧乙烷催化水合法和碳酸乙烯酯法，后两种乙二醇生产方法是目前国内外研究开发的热点。催化剂体系是催化水合法工艺的关键，重点介绍了国内外各主要公司对催化剂体系的研究进展及使用效果；碳酸乙烯酯法分为乙二醇和碳酸二甲酯联产法以及碳酸乙烯酯水解法，详细介绍了国内外各主要公司对该技术的研究进展，包括工艺流程、催化剂体系等方面。将3种乙二醇生产方法进行技术经济比较，结果表明，催化水合法和碳酸乙烯酯法在原料消耗和能耗方面占优势。并对我国乙二醇生产工艺技术提出建议。     

马克法输铝管用胶结剂的研制及应用

用粘土熟料、软质粘土及复合结合剂研制的胶结剂,用于马克法铸钢输铝管系统的胶结,其使用性能和使用寿命达到或超过了进口胶结剂的水平。     

离心压缩机可倾轴瓦油封漏油问题的解决

本文全面分析了DH80—16型离心压缩机可倾轴瓦油封漏油的原因,并介绍了可倾轴瓦油封漏油问题的解决及具体实施方案。     

二次电池电极基板用复合多孔金属材料的研究

介绍了一种复合金属多孔体的制备及其方法，首先以泡沫塑料为芯膜，经过导电化处理使其具有导电性，其次进行电沉积金属铁，再进行电沉积金属镍，经过热处理后可制备出复合金属多孔体。该复合金属多孔体用铁取代金属镍，其抗拉性能优于单质泡沫镍，同时可以降低制造成本，主要用于载体如电池电极。     

管道防腐层的失效及对策

介绍了管道防腐层失效的原因和方式。指出水和氧气是防腐层失效的原因,含水量和含氧量决定腐蚀程度,应采取有效措施对防腐层进行及时检查与修复。     

深基坑土钉支护的有限元分析

本文阐述了土钉支护的发展简史，针对济南济享大厦土钉支护开挖深基坑进行有限元分析并取得较准确的结果，说明在深基坑土钉支护设计中应注意的问题．     

转炉溅渣层与镁碳砖炉衬的结合机理

通过对生产现场带有溅渣层的转炉炉衬残砖和试验室小型坩埚溅渣试验结果进行矿相显微结构分析、研究，确定了溅渣层的矿相组成、溅渣层与ＭｇＯ－Ｃ砖结合区域的矿相结构及坩埚溅渣层自上而下的矿相分布规律，并根据矿相结构分析中观察到的烧结层、结合层和溅渣层３个区域，提出了溅渣层与镁碳砖炉衬的结合机理为化学结合、机械镶嵌与化学烧结结合及冷凝结合３种形式。     

NUMERICAL STUDY ON QUASI- STEADY FLOW OF NONNEWTONIAN FLUID IN SUCK-ROD PUMP

This paper presents a numerical method for simulation of the flow and thecalculated results of the quasi-steady axisymmetrical flow field and pressure distribution on valveball with power-law model for Non-Newtonian fluid in suck-rod pump.We believe the methodcan provide a foundation for further research and improvement of the design of suck-rod pump.