卷积神经网络和随机森林的城市房价微观尺度制图方法

随着中国城市化进程的加快,城市人口的大规模集聚带来了住房紧张的问题,房价政策制定的时效性与正确性也时刻吸引着社会的关注,因此在微观尺度下对房价进行精细化制图变得愈发重要。由于数据可获取性和现有模型精度的限制,目前已有研究均较少涉及微观尺度。本研究通过将房价数据和遥感影像相融合,构建了一种基于卷积神经网络（CNN）和随机森林（RF）的遥感影像挖掘模型,以实现在不考虑其他数据的情况下,精确、合理地进行房价的微观尺度制图。本文以武汉市作为研究区,在仅有房价数据和遥感影像的情况下,利用本文所构建的模型成功得到武汉市中心城区5 m精度的精细房价图。此外,还利用其他数据源以及挖掘技术与本文所构模型进行了对比分析。结果显示,本文所构建的模型获得了最高的房价模拟拟合优度（R²=0.805）,相比传统方法中的最高拟合优度（R²=0.653）其精度提升了23.28%,其制图结果可为政府部门规划决策及武汉市经济分布研究提供基础支撑。     

Microscale investigations of microbial communities in coastal surficial sediments

The upper millimeters of sediments are considered major locations of microbial colonization and activity. The goal of our study was to investigate variations of microbial communities in the uppermost sediment layers of the coastal Baltic Sea with emphasis on the complex interplay between microbiology and physico‐chemical sediment properties. We selected a high‐resolution methodological approach that combined the cryolanding sampling technique (spatial resolution of 250 μm) with microsensor‐, spectrophotometric and microscopic analyses. While the oxygen penetration depths in dark conditions ranged from 1.4 mm to 2.6 mm during the study period, this zone expanded by about 1 mm in light and could be divided into three micro‐horizons: (i) an upper zone with a high net O₂ production, (ii) an intermediate zone with increased O₂ consumption on account of light‐stimulated respiration and (iii) a lower zone with lower O₂ consumption. Time‐series experiments revealed a rapid response of the benthic microbial community to altered light intensities. In May and July, the net O₂ budget in the porewater of sediments was positive within 35 and 22 min after illumination, respectively, whereas in June O₂ production exceeded O₂ consumption after 112 min. The thickness of the O₂ production and O₂ consumption micro‐zones decreased from May to July coinciding with an increase in temperature. In May, sites of enhanced O₂ consumption were closely associated with subsurface maxima of microbial numbers and enzymatic activities indicating a tight coupling between photoautotrophic and heterotrophic processes between 1‐ and 2‐mm depth. In June and July, the microbial abundance and enzymatic activity hardly varied with depth. Spatial and temporal microheterogeneity of microbial distribution and activity in O₂ gradients was seen as a reflection of the complex interplay between microbiology and physico‐chemical sediment properties.     

基于纳米划痕试验的砂岩结构面宏-微观摩擦系数关系研究

基本摩擦系数是影响岩体结构面抗剪强度的重要参数。常规室内试验方法所确定的基本摩擦系数往往受矿物成分、温度等因素影响,为系统揭示结构面的基本摩擦性质,分别研究了砂岩宏观摩擦系数与微观摩擦系数,并建立了两者的关系。首先,通过X射线衍射、纳米压痕试验确定砂岩矿物组分与力学参数。其次,采用倾斜试验、直剪试验开展摩擦系数的宏观尺度研究,对规格为10 cm×10 cm×5 cm的平直结构面试样开展直剪试验,分别施加1、2、3、8、12 MPa的恒定法向应力,研究表明,摩擦系数随法向应力增加呈对数降低趋势,随剪切速率增加呈对数增长趋势。再次,采用纳米划痕试验开展摩擦系数的微观尺度研究,研究表明,低荷载条件下,长石矿物摩擦系数随荷载增加表现出先降低后保持不变的趋势,石英矿物摩擦系数随荷载增加表现出先降低后增加的趋势;此外,随着剪切速率的增加,两种矿物的摩擦系数在低荷载条件下呈增长的趋势,在高荷载条件下基本保持稳定。最后,基于摩擦系数的宏-微观摩擦系数试验结果,采用速度-状态摩擦（RSF）定律建立红砂岩基本摩擦系数与矿物摩擦系数的线性回归方程,并通过直剪试验验证了该经验关系的可靠性,其误差范围为0.17...     

用于海气界面微尺度过程观测的水槽设计与实验

为了给海气界面研究中的仿真与验证提供较全面的研究数据, 根据现有技术基础和国际前沿观测技术及设备的发展水平, 设计完成了具有造风造波能力, 并满足小尺度波浪破碎和混合、微尺度坡度场、水体内部的湍流混合、界面的热辐射及传输等过程观测需要的小型多功能水槽。实验结果表明,该小型多功能水槽各部分配合顺畅, 达到了各项观测技术的要求。该水槽可以成为海气界面研究的一个多手段、便捷的室内实验平台。     

On Modeling Dry Deposition of Long-Lived and Chemically Reactive Species over Heterogeneous Terrain

An explicit multi-layer subgrid-scheme was developed for ameso-/-scale model to consider subgrid-scale surface heterogeneity, dry deposition, biogenic and anthropogenic emission of trace gases. Since dry deposition measurements of highly reactive trace species are scarce we try to evaluate this scheme by heuristic principles. The results of simulations conducted for a 5×5 km² resolution with and without thisscheme are evaluated by using results of a model run with 1×1 km²resolution, which is taken as a `grand thruth' and which has the same resolution as the subgrid. The explict multi-layer subgrid scheme provides a similar distribution of dry deposition fluxes as the much more computationally expensive simulation with the 1×1 km² resolution.Dry deposition fluxes determined from observations give evidence that the explicit multi-layer subgrid scheme which does not require a constant flux approximation for a layer of several decameters leads to an improvement in determining the exchange between the atmosphere and the ground.Results of simulations with a microscale model show that the inhomogeneity at forest edges leads to an increase of the turbulent transports of up to a factor 4 compared to horizontally homogeneous terrain, which is assumed to be the conditions of the subgrid cells (and which is usually the assumption for the entire grid cell in mesoscale models). Inhomogeneity inside an extended stand of trees causes an overall increase of 5–10% withhigh local extremes, i.e. such an inhomogeneity results to an underestimation of dry deposition in meso-/-scale models. The effects are most pronounced for a wind direction perpendicular to the forest edge.