聚氨酯多孔弹性混合料水稳定性影响因素研究

聚氨酯多孔弹性混合料(PPEM)由聚氨酯黏结剂、橡胶颗粒和石料组成,相较于普通沥青混合料具有空隙率大、橡胶颗粒掺量高等特点。由于PPEM是大孔隙结构,使得雨天雨水易流入路面内部,进而引发水损害。为此,基于浸水马歇尔试验、冻融劈裂试验和浸水飞散试验,分别测试不同聚氨酯黏结剂、橡胶颗粒替换量、级配3种工况下PPEM的水稳定性。结果表明：对比分析不同聚氨酯黏结剂多孔弹性混合料,其中PU-III多孔弹性混合料水稳定性最好,PU-IV多孔弹性混合料水稳定性最差;当橡胶颗粒替换量不断提高时,PPEM的马歇尔残留稳定度和抗拉强度比呈线性增长,说明橡胶颗粒对PPEM水稳定性的提高有促进作用;PPEM所用级配的空隙率与其水稳定性呈负增长,水稳定性随空隙率增大而减小。     

ECA-10路面就地热再生技术研究

由于ECA-10路面低温稳定性相对较差,易开裂。尝试将就地热再生技术应用于ECA-10路面,提出就地热再生的同时掺入部分新料（加厚热再生）和原路面就地热再生（等厚热再生）两种方案,在室内对两种方案配合比设计进行研究。结果表明,两种方案的抗高温性能、抗水损害性能、抗飞散性能等均达到了SMA路面的技术要求,相比之下掺入新料更佳。     

A Computational Perspective on Projection Pursuit in High Dimensions: Feasible or Infeasible Feature Extraction

Finding a suitable representation of multivariate data is fundamental in many scientific disciplines. Projection pursuit ( $\text{PP}$) aims to extract interesting ‘non-Gaussian’ features from multivariate data, and tends to be computationally intensive even when applied to data of low dimension. In high-dimensional settings, a recent work (Bickel et al., 2018) on $\text{PP}$ addresses asymptotic characterization and conjectures of the feasible projections as the dimension grows with sample size. To gain practical utility of and learn theoretical insights into $\text{PP}$ in an integral way, data analytic tools needed to evaluate the behaviour of $\text{PP}$ in high dimensions become increasingly desirable but are less explored in the literature. This paper focuses on developing computationally fast and effective approaches central to finite sample studies for (i) visualizing the feasibility of $\text{PP}$ in extracting features from high-dimensional data, as compared with alternative methods like $\text{PCA}$ and $\text{ICA}$, and (ii) assessing the plausibility of $\text{PP}$ in cases where asymptotic studies are lacking or unavailable, with the goal of better understanding the practicality, limitation and challenge of $\text{PP}$ in the analysis of large data sets.     

Do rival political parties enforce government efficiency? Evidence from Canada 1867–2021

This paper investigates the role of inter-party rivalry in enhancing federal government efficiency in post-Confederation Canada. It tests and finds confirmation in the data for two hypotheses. The first is that the ex post size of the first versus second seat share margin is a useful metric for the ineffectiveness of political parties in policing the incumbent's spending behaviour over its period of tenure. The second is the hypothesis that shirking by the incumbent governing party is decreased by greater expected electoral contestability and expected contestability is related to the effective number of competing parties (ENPSeats) nonmonotonically. In this regard the results suggest that contestability in Canada reaches a maximum when the incumbent faces a value of ENPSeats that is closer to 2.5 than Duverger's 2.