包含局地自由对流的Monin—Obukhov相似性函数

本文从湍流产生和发展的本质出发,以湍流动能和湍流混合长为湍流输送的决定因子,用因次分析的方法得到了一套可包括局地自由对流在内的不稳定大气近地层Monin－Obukhov相似性函数。这套相似性函数不仅有较充分的理论依据,而且还有较明确的物理含意。它能在极端情况下自动蜕化出局地自由对流相似性预测形式。     

Constraints on unstable heavy neutrinos from cosmology

Cosmological scenarios with massive unstable neutrinos are discussed. Restrictions on the mass and the lifetime of the unstable neutrino are derived from (a) age and mass density of the universe and (b) the growth of primordial fluctuations. It will not be possible to accommodate unstable neutrinos with masses above ∼ 1 ke V in standard cosmology unless they have exceedingly small lifetime: Τ <5 × 10⁸ s.     

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????????λ???????????????3????????????????????編???н??????????????????????????????????2007~2010?????20??ENVISAT ASAR?????÷????????????????????Э??????????У?????????????????й????????????Э?????????????????????3.1 mm²??????0.6mm²????????80%??e-folding???????????1.5 km?????0.21 km????????86%????????編??????Ч??У????????е??????λ?????     

日照水库及周边区域综合地质条件分析

日照水库是1959年建成的一座大(二)型水库,位于日照市东港区驻地以西16 km处的付疃河中游,控制流域面积548 km2,是日照城市及国民经济发展的最重要水源保障。近年来日照市经济社会飞速发展,特别随着"山东精品钢基地"等大项目的开工建设,供水安全形势愈发严峻,如何维护日照水库和保护这一水源地更是被提到了重要的议事日程。先行研究分析流域地质条件,是做好日照水库保护建设工作的重要基础。     

对陡坡陡崖引发地质灾害的潜在影响范围进行建模分析

陡坡陡崖作为一种特殊的地形地貌,是造成滑坡、泥石流等各种地质灾害的重要因素之一。由陡坡陡崖引发的地质灾害会破坏人造地物,对人类的生命财产安全造成严重危害。本文利用DEM数据提取了浙江省温州市的陡坡陡崖,对温州市陡坡陡崖的影响范围进行系统研究,构建了温州市陡坡陡崖的潜在滑坡方向模型,并确定其对人造地物（如道路、房屋）的影响。本文主要研究内容有以下两个：①提取陡坡陡崖并对其潜在滑坡方向进行建模;②根据影响范围提取受影响的人造地物并建立基础数据库。结果表明,温州市的陡坡陡崖数量多,分布范围广且集中,其引发的地质灾害会对人造地物造成严重的潜在影响。本文构建的温州市基础数据库可以描述陡坡陡崖潜在影响的房屋和道路的位置,确定灾害重点防治区域,为温州市的灾害防治工作提供服务。     

Simulation of the Askervein flow. Part 2: Large-eddy simulations

Large-eddy simulations of the neutrally stratified flow over the Askervein Hill were performed, to improve the knowledge of the flow obtained from field measurements and numerical simulations with Reynolds averaged Navier-Stokes (RANS) methods. A Lagrangian dynamic subgrid model was used but, to avoid the underdissipative character near the ground, it was merged with a damped Smagorinsky model. Simulations of a flat boundary-layer flow with this subgrid model showed that the turbulent vertical motions and shear stress were better resolved using grids with a stream to spanwise aspect ratio Δx / Δy = 2 than with an aspect ratio Δx / Δy = 1. Regarding the flow over the Askervein Hill, it was found that large-eddy simulations provide an acceptable solution for the mean-velocity field and better predictions of the turbulent kinetic energy in the upstream side of the hill than the model. However, as with the model, grid convergence was not achieved in the lee side and the size of the zone with reversed flow increased with the grid refinement. Nevertheless, the existence of the intermittent separation predicted with unsteady RANS in part one of this work seems unquestionable, due to the deceleration of the flow. In our opinion, a better modelling of the decelerating boundary layer in the lee side is required to improve the results obtained using equilibrium assumptions and achieve grid convergence.     

渝利铁路青石岩段边坡危岩体稳定性评价及防治措施研究

渝利铁路青石岩段为深切河谷型边坡,该边坡表部岩体在风化缷荷作用下结构复杂且稳定性差。此外,浅表层岩体在降雨、地震及工程开挖等影响下,局部已经出现了不同模式不同规模的变形失稳现象,严重影响工程建设和运营期间的安全。因此,本文根据边坡岩体结构特征及风化缷荷特征等工程地质条件,结合不同失稳模式的危岩体,提出了相应的稳定性评价理论和方法。最后,针对不同规模和不同稳定状态下的危岩体提出了有效的防治措施。     

海底地形数据组织与可视化选取技术

海洋测绘数据信息化是构建智慧海洋的基础, 而海底地形数据是海洋测绘数据中的重要内容。为更加便捷和高效地 管理与利用地形数据, 本文结合工程实际需求, 研发了海底地形数据管理平台。首先, 基于海底地形数据的特点, 提出多分 辨率海底地形组织模型, 对不规则区域的海底地形进行多分辨率模型构建, 实现了对多波束实测数据的组织管理; 在此基础 上, 提出了多尺度海底地形分级渲染优化算法与海底地形数据空间截取算法, 利用分级渲染与数据裁剪算法实现对海底地形 数据的可视化表达预览和选取服务; 最后, 以典型的多波束测深数据为例, 基于研发平台完成了数据从存储 、组织管理到可 视化预览选取的一体化管理与服务, 验证了本文算法的可靠性与实用性, 同时可为海底地形数据管理服务提供一定参考。     

Terrestrial surface-area increment: the effects of topography,DEM resolution,and algorithm

The area increment of land surface compared with its projected area is an effect of topographic relief and is also a source of environmental variations. To examine the effects of topography and data resolution on surface area calculation, we calculated incremental area coefficients (IACs), based on two different algorithms, for a DEM of China at a series of spatial resolutions. Sampling the DEM with a regional network of 50?km?×?50?km cell size, we explored the relationships among the two IACs and topographic features. Both IACs studied were exponential functions of resolution. At 30-m resolution, the IACs were 4.31 and 4.89% over China, respectively. The largest increment for a 50?km?×?50?km cell was >45%. Between the IACs there was a linear relationship that varied with DEM resolution. Hierarchical variation partitioning revealed that the factors included contributed in a very similar percentage composition to the two IACs, mean slope (37.5 or 38.7%) and standard deviation of slope (22.3 or 19.6%) at local scale dominated the area increment, followed by regional elevation range. Data resolution contributed about 10%, while the deviation of slope exposure only had minimal (1.4 or 1.7%) impact on surface-area increment. For a specific type of geomorphology, a threshold resolution of DEM can be determined, below which the surface-area increment (i.e., IAC) is negligible. Our results provided the first comprehensive estimate of the contributions of the topographic features, DEM resolution, and algorithms for the surface-area increment, and indicated the scale-related properties and potential environmental consequences of topographic heterogeneity in various estimates of natural resources and ecosystem functions when area needs to be taken into account.