Exurbia from the bottom-up: Confronting empirical challenges to characterizing a complex system

We describe empirical results from a multi-disciplinary project that support modeling complex processes of land-use and land-cover change in exurban parts of Southeastern Michigan. Based on two different conceptual models, one describing the evolution of urban form as a consequence of residential preferences and the other describing land-cover changes in an exurban township as a consequence of residential preferences, local policies, and a diversity of development types, we describe a variety of empirical data collected to support the mechanisms that we encoded in computational agent-based models. We used multiple methods, including social surveys, remote sensing, and statistical analysis of spatial data, to collect data that could be used to validate the structure of our models, calibrate their specific parameters, and evaluate their output. The data were used to investigate this system in the context of several themes from complexity science, including have (a) macro-level patterns; (b) autonomous decision making entities (i.e., agents); (c) heterogeneity among those entities; (d) social and spatial interactions that operate across multiple scales and (e) nonlinear feedback mechanisms. The results point to the importance of collecting data on agents and their interactions when producing agent-based models, the general validity of our conceptual models, and some changes that we needed to make to these models following data analysis. The calibrated models have been and are being used to evaluate landscape dynamics and the effects of various policy interventions on urban land-cover patterns.     

Wenchuan Earthquake： Way of thinking is changed

On 12 May, 2008, at 14：28：04 local time, an Ms 8.0 earthquake struck the Wenchuan County, Sichuan Province, in southwest China （Figure 1）. This quake left about 70,000 people dead, 18,000 missing and over 370,000 injured. In the 75 days after the main shock, 20,000 aftershocks were recorded, which included 241 with Ms≥4.0, 205 with 4.0≤M≤4.9, 30 with 5.0≤Ms≤5.9, and 6 with Ms≥6.0. The largest aftershock took place 13 days after the main shock, in Qingchuan County, 110 km northeast of the epicenter of the quake （Chen, 2008）. The losses from the quaketriggered geological disasters accounted for over a third of the total quake losses, which is extremely rare in the history of earthquake disasters. Secondary disasters, such as landslides, rockslides, landfalls, debris flows, etc., were widely distributed. Large numbers of buildings collapsed, including ones with steel reinforcing in the area of the epicenter. Infrastructure was badly damaged. In many areas, communications, and power and water supplies were cut off. The earthquake left over 35 large quake-dammed lakes, which threatened further disasters in the catchment areas.     

桩静载荷试验快速法与慢速法对比研究

通过对54根管桩静载荷试验快速法与慢速法对比试验研究,找出了在各级荷载作用下,快速法与慢速法沉降差异规律及快速法与慢速法分别得出的极限承载力差异规律;得出了将快速法静载试验下的沉降及单桩极限承载力修正成慢速法静载试验的沉降及单桩极限承载力的公式;提出了适应天津地区管桩的快速法静载试验方法。     

饱和粉砂不稳定性的试验研究

通过对净砂和级配良好粉砂(含10 %粉土)进行一系列三轴固结不排水试验（CU）,研究了粉土、孔隙比和围压对饱和粉砂不稳定性的影响。试验结果表明,净砂与粉砂在不排水剪切条件下均会出现应变软化现象（即不稳定性）。同一围压下脆性指数(IB)随孔隙比增加,但不稳定线的应力比随孔隙比增加而减小。引用等效粒间孔隙比(ege)后,净砂和粉砂在ege-ln p?平面上拥有基本相同的临界状态线。在临界状态理论及等效粒间孔隙比的基础上,提出在同一修正状态参数(?ge)下净砂和级配良好粉砂有相似的不稳定性。     

三维抛物方程Douglas交替方向隐格式的稳定性和收敛性

作者研究三维变系数抛物方程 Douglas交替方向隐格式的稳定性和收敛性。采用 H1能量估计方法 ,证明格式按离散 H1范数是绝对稳定的 ,并且收敛阶为 O(Δ t2 + h2 )     

165°E赤道太平洋溶解氧垂直分布异常分析

根据1986—1990中美热带西太平洋海气相互作用8个航次合作综合调查资料，分析了1987年10月赤道中西太平洋165°E（10°N－6°S）次表层水形成溶解氧最大值的原因。1986－1987年E1Nino衰退时期，该海域赤道附近在E1Nino强盛时期下沉的次表层水开始回升，短时期内形成了类似于中、高纬度海域的理化环境，使浮游生物在混合层内聚集生长，最终导致溶解氧含量在次表层出现最大值和过饱和含量。     

在各类天气系统影响下石臼港沿岸波浪场的分布

本文查阅了从１９７３－１９８５，１３年的历史资料，对石臼港沿岸波浪场进行了详细的分类、统计分析和计算，提出了各类较强天气系统影响石（即指石臼港）的极端区域，同时获得了石港沿岸各类天气系统影响下的波浪分布特点以及波高计算式，为保障石港的生产及港口建设为石港的波了提供了有益的分析数据和预报手段。     

庵东浅滩沉积分带和沉积速率

杭州湾南岸的庵东浅滩具有地貌特征、沉积类型和沉积构造各异的三个沉积相带。垂向沉积带为潮滩沉积体的盖层,以泥滩、粘土质粉砂和薄砂泥交互层为特征;改造带位于中低潮位线附近,以粉砂滩、潮沟系统、粉砂沉积和沙波层理为特征;横向沉积带为潮滩堆积体的基础,以滩坡、粉砂及细砂质粉砂沉积、冲刷-充填构造为特征。据潮汐韵律层的统计,庵东浅滩沉积速率的短周期分量,常态条件下为每半日潮周期0.1～2.0cm,异常条件下可达每半日潮周期4～64cm。沉积速率的长周期分量,据地形对比和~(210)Pb推算,垂向沉积带为2～4.5cm/a;改造带中的粉砂滩为2.1～4.5cm/a,潮沟影响范围内为1～10~1cm/a量级;横向沉积带则以高于50cm/a的高沉积速率和变幅为主。近10年来,该浅滩的年淤积量为6×10~7t/a,其中85％集中于横向沉积带。     

水中荧光计及其在海洋现场探测中的应用

本文描述了近几年来我们首次研制成功的３种类型的水中荧光计系统及其应用测量结果：１．用于水体混合扩散实验研究的水中荧光计，对罗丹明Ｂ浓度测量范围为１×１０－６～１×１０－１０ｇ／ｃｍ３；２．拖曳荧光计系统，能在２～８０ｍ水深内进行水平拖曳平稳地工作，拖曳速度为０～８ｋｎ，除检测罗丹明Ｂ外，还可检测无机悬浮物质的含量，检测范围为２～２０００ｍｇ／ｄｍ３；３．用于测量海中浮游植物体内叶绿素ａ浓度的水中荧光计，测量范围为１×１０－６～１×１０－９ｇ／ｃｍ３。用荧光法测量海中物质是近代新发展的一种简便、快速、灵敏度高、用途极其广泛的测量技术，有着重要的应用价值。