确保砼外观质量的施工技术措施

随着桥梁工程建设越来越注重砼外观质量,特别是城市及旅游景点的桥梁工程,出露的结构物往往要求一次浇筑成型,面层平整光滑、色泽均匀,棱角顺直、无碰损和污染,不需做任何外装饰,直接采用现浇砼的自然色作为饰面。文章通过模板、砼配合比、砼浇筑及振捣等方面详细阐述了确保砼外观质量的技术措施。     

浅析影响水稳混合料质量的因素及施工过程中的质量控制

通过对HAL1标的水稳碎石基层的施工,笔者对影响水稳碎石混合料质量的因素及施工过程中的质量控制作了初步的总结。同时从混合料级配、水泥剂量、含水量、压实度、养护及钻芯等几方面,对水稳混合料及施工过程中的质量控制提出了几点建议。     

Controlling for Burnout in Estimating Mortgage Prepayment Models

Burnout is a consequence of unobservable predictive variables. This paper describes a methodology for estimating mortgage prepayment models which corrects for burnout. The paper generalizes the approach of Deng, Quigley, and Van Order (Econometrica, 68, 275–307, 1998) and Stanton (Rev. Finan. Stud.8, 677–708, 1995) in modeling the impact of unobservable variables as a probability distribution. The estimator is applied to a sample of loan histories and the results compared to a conventional logit analysis of the data. Predictions and simulations from both models are compared to illustrate the properties of the new estimator.     

Cyclical correlations, credit contagion, and portfolio losses

We model aggregate credit losses on large portfolios of financial positions contracted with firms subject to both cyclical default correlation and direct default contagion processes. Cyclical correlation is due to the dependence of firms on common economic factors. Contagion is associated with the local interaction of firms with their business partners. We provide an explicit normal approximation of the distribution of portfolio losses. We quantify the relation between the variability of global economic fundamentals, strength of local firm interaction, and the fluctuation of losses. We find that cyclical oscillations in fundamentals dominate average losses, while local interaction causes additional fluctuations of losses around their average. The strength of the contagion-induced loss variability depends on the complexity of the business partner network.     

Customer segmentation using unobserved heterogeneity in the perceived-value–loyalty–intentions link

Multiple facets of perceived value perceptions drive loyalty intentions. However, this value–loyalty link is not uniform for all customers. In fact, the present study identifies three different segments that are internally consistent and stable across different service industries, using two data sets: the wireless telecommunication industry (sample size 1122) and the financial services industry (sample size 982). Comparing the results of a single-class solution with finite mixture results confirms the existence of unobserved customer segments. The three established segments are “rationalists”, “functionalists” and “value maximizers”. These results point the way for value-based segmentation in loyalty initiatives and reflect the importance of a multidimensional conceptualization of perceived value, comprising cognitive and affective components. The present results substantiate the fact that assuming a homogeneous value–loyalty link provides a misleading view of the market. The paper derives implications for marketing research and practice in terms of segmentation, positioning, loyalty programs and strategic alliances.     

高温多雨区SMA路面施工应用关键技术研究

SMA沥青混合料的材料组成特性导致施工难度较大,对施工各环节因素的敏感性较强.为提高广东高温多雨区重载交通路段SMA路面的施工质量,以广东紫惠高速项目为依托,开展SMA沥青混合料的下承层界面处理、混合料拌制工艺参数设定、装载与运输、摊铺设备参数、碾压工艺、施工温度控制等全过程施工环节监控,实现各环节的关键参数调整优化.采用体积法进行SMA沥青混合料设计,可以均衡混合料密实性与骨架嵌挤性能,获得良好的密水性能和抗车辙性能.基于无核密度仪研究了碾压工艺对SMA混合料的压实影响,沥青混合料压实度经历先增加后变小的现象,碾压过程应均衡压实度与路表构造来控制钢轮碾压遍数和路面温度.     

冷补沥青混合料修补路面技术及应用

用冷补沥青混合料修补路面坑槽等病害,具有方便、快捷、安全易施工等优点,是公路养护方面较为理想的路面修补材料。     

基于Copula的道指与恒指的尾部相关性分析

Copula函数能有效地刻画随机变量间的非对称性和尾部相关性。在研究当道琼斯工业指数与恒生指数的相关性时,采用非参数核密度估计拟合边缘分布。并应用Kol mogorov-Smirrnov检验三种Archi medean Copula函数。研究发现参数值θ=0.2221的Clayton Copula可以用于描述下尾相关性,而θ=1.1105的Gumbel Copula可用于描述上尾相关性。     

Option Pricing with Heterogeneous Expectations

This paper re-derives the finite mixture option pricing model of Ritchey (1990), based on the assumption that the option investors hold heterogeneous expectations about the parameters of the lognormal process of the underlying asset price. By proving that the model admits no riskless arbitrage, this paper justifies that the entire family of finite mixture of lognormal distributions is a desirable candidate set for recovering the risk-neutral probability distributions from contemporaneous options quotes. The parametric method derived from the model is significantly simpler than the nonparametric method of Rubinstein (1994) for recovering the risk-neutral probability distributions from contemporaneous option prices.     

国外道路建设用沥青新型混合料

历史经验表明，经济危机往往孕育着新的科技革命。正是科技上的重大突破和创新，推动经济结构的重大调整，提供新的增长引擎，使经济重新恢复平衡并提升到更高水平。道路建设中的沥青新型材料就是在科技的引领下，不断推陈逝新。