调制块比在地震中期预报中的应用

从研究震前大范围的调制比异常出发,定义调制块比的概念,并研究了国内的某些震例。结果表明,调制块比平均异常时间１．２５年,平均异常开始至发震时间２．０年,平均异常结束至发震时间１．０年,调制块比异常对７级以上地震显示为高值异常特点。另外,调制块比可反映部分地震前的中期地震活动性异常。当地震孕育到中期阶段时,震源周围地区出现小震调制比异常区域增加的异常。     

南极菲尔德斯半岛湖泊沉积物的稀土地球化学

本文研究了燕鸥湖、西湖和基太湖湖泊沉积物的稀土地球化学。这些湖泊沉积物的稀土分布模式与菲尔德斯半岛第三纪火山岩非常相似，它们的物质来源是菲尔德斯半岛岛弧火山岩。湖泊沉积相与冰碛层稀土模式的差异，反映了它们经历的化学风化程度不同、粘土含量不同。Ｃｅ异常意味着每个湖泊沉积旋回结束的阶段气候是比较干燥的。湖泊沉积物的稀土含量和分布模式变化小，也意味着在中晚更新世时气候是比较干燥的。     

中国城市居民的家庭代际分/合居行为及其影响要素——以成都市为例

1978年以来,中国家庭小型化趋向非常显著,尤以代际分居为核心诱因,代际分居对转型期中国的社会稳定、家庭和睦乃至住房市场都构成了很大的影响。而且,中国的代际分居现象及其机制和西方社会存在根本的不同,此文讨论了转型期基于代际分居率和家庭生命周期的中国城市居民分/合居行为的概念模型,随后选择成都市主城区进行了实证,因为该地区不但社会经济发展速度快,户籍居民的老龄化趋向明显,而且兼受中国传统文化和西方文化的耦合影响。与西方发达社会基于家庭生命周期先合居、后分居的规律不同,中国城市居民家庭居住行为呈现出合居—（小）分居—合居—分居—（小）合居—（小）分居—（小）合居的变化过程。采用2012-2013年的实地调研数据,采用Pearson相关性分析法提取主要影响因素,后采用二元logistic 回归方法研究了主要因素对居民分/合居行为的显著性和正负影响,并对不同年龄段的城市居民家庭代际分/合居行为的代际分/合居选择及其影响因素进行了分析。结论如下：① 文化程度、配偶健在、家庭人均收入、父母应帮子女成家、父母应帮子女买房、与子女/父母代际分居意愿、作息习惯、饮食习惯、安静/热闹偏好、卫生习惯、居家习惯和私密空间习惯与家庭代际分居率正向显著;② 年龄、家庭居住面积、父母应帮忙抚养孙辈、（子女）应该养老、父母/子女应临近居住、养儿防老、养育习惯等变量与家庭代际分居率负向显著;③ 不同年龄段居民的代际分/合居选择的影响因素及其显著度有所差异。     

梁板分离式分层隔震结构减震原理研究

为了拓宽隔震技术的应用范围,提出了梁板分离式分层隔震结构概念,其核心思想是将框架结构或框架剪力墙结构中的所有楼层或某些楼层的全部或部分楼板通过橡胶隔震支座支承于梁上。建立了分层隔震结构的动力分析模型,利用自编程序按时程分析法和振型分解反应谱法分别计算了不同工况下分层隔震结构的地震反应,运用隔震技术的基本原理和振型分析法分析了刚度比和场地条件等因素对减震效果的影响。发现了刚度比变化过程中分层隔震结构的两个极限状态,并利用其中之一初步判断减震效果。     

基于试验与模型的根系增强抗剪强度分析

在总结近代学者对植物根系固土作用机制研究的基础上,采用大盒直剪试验与物理模型,对重庆缙云山地区6种常见植物:马尾松、香樟、广东山胡椒、四川大头茶、白毛新木姜子、四川山矾根系的增强抗剪强度进行对比。通过自制的大盒直剪仪对植物实际固土效果进行了测定,该大直剪仪具有简单、经济、易行等特点。通过对多种植物根系进行抗拉试验和根土复合体受力分析,确定了植物根系的抗拉强度与植物根面积比率。利用Wu模型对6种植物的根系固土效能进行模型计算。结果表明,不同的植物根系类型对增强抗剪强度值的影响非常显著。在重庆缙云山地区的土壤质地情况下,Wu的根土复合体模型高估了根系增强土壤的抗剪强度约为90%。基于该结论,为使Wu模型计算的根系固土强度值较为准确,修订Wu模型中的k值为0.63。     

Hydrological characteristics of vegetated river flows: a laboratory flume study

Abstract

Laboratory flume experiments were undertaken to measure the vertical profiles of mean flow velocity for three different flow discharges and four different stem densities of Hydrilla verticillata. The data were used to calculate three parameters, namely Manning's roughness coefficient, the Reynolds number and the Froude number. In addition, empirical equations were obtained for the vertical distribution of measured flow velocity within the transitional zone and above the plant canopy. The results show that: (a) the vertical distribution of measured flow velocity exhibits three zone profiles; (b) Manning's roughness coefficient decreases with increasing depth-averaged flow velocity; (c) the relationship between Manning's roughness coefficient and the depth-averaged flow velocity is within the smooth left inverse curve; (d) Manning's roughness coefficient significantly changes with increasing density of Hydrilla; (e) the Froude number is independent of the density of Hydrilla; and (f) both the Reynolds number and the Froude number increase with increasing depth-averaged flow velocity.

Citation Shi, J.Z., Li, Y.-H., Hughes, J.M.R., and Zhao, M., 2013. Hydrological characteristics of vegetated river flows: a laboratory flume study. Hydrological Sciences Journal, 58 (5), 1047–1058.

Editor Z.W. Kundzewicz     

新疆和周边地区地壳厚度和Vp/Vs比值变化的接收函数约束

我们用修订后的接收函数H-K叠加算法估计了新疆和周边地区90个地震台站下的地壳厚度和波速比Vp/Vs.该地区平均地壳厚度约为52 km,变化范围约为33～79 km.最厚地壳位于西昆仑山的TAG台站,最薄地壳在塔拉斯-费尔干那断层附近的NRN台站.对每个台站的点地壳厚度估计结果进行了线性各向同性变差模型的标准克里金空间...     

城市住宅小区容积率时空分异研究——以大连市内四区为例

以大连市内四区为例,将城镇地籍调查数据与互联网房产数据相结合作为基础数据,通过ArcGIS软件生成住宅小区点数据的空间分布图,对大连市住宅小区容积率的时间演变和空间分布进行研究,并利用锡尔指数计算住宅小区容积率的空间差异量化测度指数,最后阐述住宅小区容积率空间差异的机制。结果表明：① 1992~2016年大连市住宅小区的数量在持续发展时期最多,平均容积率展现出波动上涨的趋势。② 区：大尺度包括冷炳荣住宅小区容积率整体上呈现出不均匀性和破碎性,局部又呈现出混乱性和复杂性,东部地区小区容积率分异比西部大。③ 中山区空间差异量化测度指数最高为0.831,甘井子区最低为0.125,西岗区与四区整体格局最为相近。极低等级容积率空间分异指数最高,容积率分异指数由两极向中间递减。大连市住宅小区容积率空间差异主要体现在区域内,其对研究区容积率空间分异影响较大。④ 住宅小区容积率空间差异的主要原因为下垫面性质对住宅小区建设的限制、区位的优良性对住宅类型的指向、城市规划对土地利用的导向、极差地租与容积率的相关性、小区建设成本对容积率的影响。     

Multivariate properties of extreme precipitation events in the Pearl River basin,China: Magnitude,frequency, timing,and related causes

Daily precipitation/temperature data collected at 74 weather stations across the Pearl River basin of China (PRBC), for the years 1952–2013, were used to analyse extreme precipitation (EP) processes at annual and seasonal scales in terms of precipitation magnitude, occurrence rates, and timing. Peak‐over‐threshold sampling, modified Mann‐Kendall trend tests, and Poisson regression model were utilized in this study. Causes driving the observed statistical behaviours of EP were investigated, focusing particularly on the impacts of temperature change and the El Niño–Southern Oscillation (ENSO). EP events, which occur mainly during April and September, are most frequent in June. At an annual scale, they are subject to relatively even interannual distributions during the wet season. Significant trends were observed in the magnitude, frequency, and timing of EP events during the dry seasons, although no such trends were seen during the wet seasons. Seasonal shifts in EP can easily trigger sudden flood or drought events and warming temperatures, and ENSO events also have significant impacts on EP processes across the PRBC, as reflected by their increased magnitude and frequency in the western PRBC and decreased precipitation magnitudes in the eastern PRBC during ENSO periods. These results provide important evidence of regional hydrological responses to global climate changes in terms of EP regimes in tropical and subtropical zones.     

Estimation of the 3D correlation structure of an alluvial aquifer from surface-based multi-frequency ground-penetrating radar reflection data

Knowledge about the stochastic nature of heterogeneity in subsurface hydraulic properties is critical for aquifer characterization and the corresponding prediction of groundwater flow and contaminant transport. Whereas the vertical correlation structure of the heterogeneity is often well constrained by borehole information, the lateral correlation structure is generally unknown because the spacing between boreholes is too large to allow for its meaningful inference. There is, however, evidence to suggest that information on the lateral correlation structure may be extracted from the correlation statistics of the subsurface reflectivity structure imaged by surface-based ground-penetrating radar measurements. To date, case studies involving this approach have been limited to 2D profiles acquired at a single antenna centre frequency in areas with limited complementary information. As a result, the practical reliability of this methodology has been difficult to assess. Here, we extend previous work to 3D and consider reflection ground-penetrating radar data acquired using two antenna centre frequencies at the extensively explored and well-constrained Boise Hydrogeophysical Research Site. We find that the results obtained using the two ground-penetrating radar frequencies are consistent with each other, as well as with information from a number of other studies at the Boise Hydrogeophysical Research Site. In addition, contrary to previous 2D work, our results indicate that the surface-based reflection ground-penetrating radar data are not only sensitive to the aspect ratio of the underlying heterogeneity, but also, albeit to a lesser extent, to the so-called Hurst number, which is a key parameter characterizing the local variability of the fine-scale structure.