不同分散剂对红黏土粒度分布的影响

红黏土由于土中游离氧化铁的存在,具有特殊的团粒结构。对于用密度计法进行红黏土的颗粒分析试验,各类规范中均建议加入分散剂。为更好评估土样分散的效果,运用分形理论,用分维值这一参数来描述土颗粒粒度特征。利用江西某地的红黏土,分别进行加入不同种类分散剂后的颗粒分析试验。结果表明,试样中加入六偏磷酸钠溶液作为分散剂后,得到的分维值较大,土颗粒集合体更分散。可见不同分散剂对于试验用红黏土的分散效果相差较大,加入适宜的分散剂才能更好地得到红黏土的实际粒度分布情况。试验结论对进一步认识和掌握红黏土的工程性质具有一定意义。     

狮子洋断裂带第四系沉积规律研究

为了了解狮子洋断裂第四纪地层的划分情况,通过在断裂带区域进行浅层地震勘探和水上钻探,钻取岩芯、开展沉积相划分和采集系列的年代学样品,采用14C测年、粗颗粒石英或细颗粒石英的OSL测年两种方法,对钻孔岩芯的绝对年龄进行测定,研究狮子洋断裂带第四系的沉积规律。结果表明,深圳地区水域第四系为中更新世、晚更新世和全新世沉积,并且新获得的沉积最老年龄为18.5万年,约18万年以来地层年代学框架为深圳地区活动断层探测提供了时间标尺。     

浅层地下水监测井快速成井工艺试验

地下水监测井是进行地下水各项参数监测的重要途径。随着监测技术的发展,对于成井井管直径的要求越来越小,但是受常规成井工艺的制约。为保障填砾止水工序顺利实施,井管与井壁之间间隙需求较大,使得监测井井径依然较大,而且常规成井工艺工序烦琐、效率低,对地下水填砾止水分层的精细化、准确度较差。依据地下水监测井的目的和特点,通过试验与分析对常规成井工艺进行优化,采用预制滤水管体和止水管体替代填入砾料和止水材料的流程,简化成井工艺,同时满足小口径成井需求,可有效提高钻进效率,降低施工成本,精细准确地进行滤水段和止水段分层,并分析了优化后成井工艺的可靠性,为优质高效地建设浅层地下水监测井提供技术支撑。     

Firm Size and Work Compensation in China

Remarkably, recent research on the Chinese labor market has suggested that the situation in China is inconsistent with the stylized fact that large firms pay higher wages and offer more generous benefits. Expanding the empirical basis from 78 to 300 000 industrial firms, I overturn theprevious result andshow that wage determination in the averagefirmfits the international norm. Exploring subsamples of firms I also point to a likely source for the conflictingfindings： firm size is positively correlatedwith the average wage in private firms, but negatively correlated with the average wage in the state-owned sector. These novel results couM guide future studies aiming to understand the sources of the firm size wage premium, and, in particular, studies that target the largest industrial labor market in the world     

Environmental Efficiency and the Optimal Size of Chinese Cities

The spatial distribution of population and economic activities has important impacts on both economic growth and the environment. This paper uses a slack‐based measure to estimate the total factor environmental efficiency (TFEE) of 286 Chinese prefectural‐and‐above cities for the period 2002–2013. In particular, the relationship between city size and TFEE is investigated. The findings also show an inverted U‐shaped relationship between TFEE and city size, which implies an optimal city size of 16.68 million residents in China. According to this estimate, most Chinese cities may be undersized due to the migration restrictions of the hukou registration system and, hence, suffer from great environmental efficiency losses. The estimated low average TFEE value of Chinese cities also suggests the large potential for efficiency improvement. Thus, government policies should focus on relaxing migration restrictions and encouraging the development of large cities.     

Size of nested cities

Models of cities based on conventional spatial market theory are unable to replicate a realistic size distribution. The stochastic process approach to size distribution, which assumes proportionate growth, does not provide an economic foundation for spatial trades. There is an apparent irreconcilability. We propose that since there is a continuum of equilibria in models of spatial markets with endogenous location, proportionate growth can work as equilibrium selection. We present computations for an urban configuration that has not been presented in the literature before. A small city locates inside a larger city's agricultural supply zone. This generates a larger variation in city size that may include a realistic size distribution.     

不同粒级煤配合炼焦实验研究

通过对不同粒级配合煤进行不同细度的配合炼焦试验研究,得出：当配合煤细度控制在77%时,所得焦炭综合指标质量较好,此时,焦炭显微强度58.49%、结构强度86.41%、焦炭反应性34.8%、反应后强度49.6%。     

基于DEM的沥青混合料劈裂强度尺寸效应

为了探究沥青混合料劈裂抗拉强度的尺寸效应,应用颗粒离散元数值模拟技术,对4种级配（AC-13、AC-16、AC-20、AC-25）不同尺寸的沥青混合料进行巴西劈裂数值试验,每组级配模型尺寸缩放系数分别为0.6、0.8、1.0、1.2、1.4,并建立尺寸缩放系数与沥青混合料抗拉强度尺寸效应的关系,得到4种级配下的沥青混合料抗拉强度的临界尺寸和临界强度。试验结果表明,4种级配的沥青混合料抗拉强度均具有明显的尺寸效应,级配越大,尺寸效应越不明显,级配AC-25的试样抗拉强度尺寸相关系数约为级配AC-13试样的94.37%。     

家庭规模、子女状况与农民工幸福感

为了考察农民工家庭规模、幸福感的关系,以及子女状况在其中的作用,基于2021年中国综合社会调查（CGSS）的微观数据进行实证分析。结果显示,家庭规模、子女状况、幸福感之间存在两两正相关关系;子女状况在家庭规模与幸福感之间起部分中介作用。因此,提高农民工幸福感可以从扩大农民工家庭规模,支持农民工家庭子女数量增加的角度入手,也为减轻社会老龄化造成的负担提供了有力支持。     

环保疏浚底泥资源化利用研究进展

环保疏浚技术被广泛应用于国内外湖泊、河流污染底泥的治理,针对疏浚产生的底泥,传统的吹填等处置方式会对环境产生潜在的危害,因此,其资源化利用也越来越受到人们的关注。对目前国内外疏浚底泥资源化利用方式进行总结,对土地利用、制备建筑材料和污水处理材料等资源化利用方式进行讨论,认为制备建筑材料是疏浚底泥资源化利用的重要途径。