基于遥感影像的西安世园会园区地理变化监测研究

基于2006年4月～2011年4月的多级、多源、多时相遥感影像,利用摄影测量、图像处理、影像解译、信息分类等相关技术,对西安世界园艺博览会园区不同时期的土地利用、地理变化、园区建设进度变化进行监测解译和对比分析。研究结果表明:西安世界园艺博览会侧重植被与湖泊的建设,地理环境优化得到明显的改善。截至2009年4月,世园会的主体结构已布局好;2011年3月,园区内的道路、附属设施、湖泊、建筑物等已基本建成;2011年3月～4月,主要为展示植物等移入时间。     

Experimental study on the viscoelastic behaviors of debris flow slurry

The rheological properties of most liquid in nature are between liquids and solids,including both elastic changes and viscosity changes,that is socalled "viscoelastic".Dynamic oscillatory test was used to quantitatively study the distinct viscoelastic behaviors of debris flow slurry in the shear stress conditions for the first time in this study.The debris flow slurry samples were from Jiangjiagou Ravine,Yunnan Province,China.The experimental results were found that at the low and middle stages of shearing,when the angular velocity ω<72.46 s-1,the loss modulus(G") was greater than the storage modulus(G’),i.e.G">G’.At the late stage of shearing,when the angular velocity ω≧72.46 s-1,the storage modulus was greater than or equal to the loss modulus,i.e.G’≧G",tanδ≦1(where phase-shift angleδ=G"/G’),and the debris flow slurry was in a gel state.Therefore,the progress of this experimental study further reveals the mechanism of hyperconcentrated debris flows with a high velocity on low-gradient ravines.     

鲁西地区“泰山红宝石”的发现及其地质特征

在山东新泰市新太古代泰山岩群变质岩系中,首次发现宝石级红刚玉,又称红宝石,商业名称暂定为"泰山红宝石"。红宝石产于鲁西地区新太古代二长花岗岩的壳源岩石包体之中,包体岩性以黑云更长变粒岩、黑云片岩、角闪石岩、斜长角闪岩、浅绿色含铬二云片岩为主,是新太古代古老地壳的深融残留;红刚玉与浅绿色含铬二云片岩关系密切,推测是新太古代变质岩中原岩残留斑晶矿物。     

泰安市旅游生态能值分析

运用能值理论, 从区域生态经济系统的视角, 提出旅游生态能值理论, 论述旅游输入能值、旅游输出能值、旅游能值交换率、旅游可持续发展指标等概念、测算依据和计算方法, 并对2010 年泰安区域生态经济系统内旅游可持续发展水平进行旅游生态能值分析。实证研究表明:(1) 泰安区域生态经济系统可利用能值为15867.32×10¹⁹ sej, 旅游输入能值为1766.59×10¹⁹ sej, 旅游输出能值为679.40×10¹⁹ sej, 旅游能值交换率为2.60。旅游可持续发展能值指标TSEI为1.76, 处在可持续发展阶段;(2) 运用旅游生态能值的理论评价旅游可持续发展水平是可行的。     

西安市停车资源现状与空间分布研究

针对目前各大中城市私有汽车数量不断上升、城市停车资源趋于饱和甚至过载的现状,以西安市三环内停车资源为例,分析了其空间布局、配套设施以及建设投资主体等方面的资源分布发展现状,并制作了相关专题地图,为城市停车资源修建与管理提供参考.结果 表明,西安市停车资源整体呈聚集分布,在经济发展较好的区域聚集特征明显;由政府部门投资兴...     

San Diego trough geotechnical test area

Abstract

The San Diego Trough Geotechnical Test Area, located about 24 km southwest of San Diego in a water depth of about 1.2 km, lies near the base of the Coronado Escarpment directly north of the Coronado Fan. A new bathymetric map delineates a shallow basin in the soft, highly plastic, clayey silts flooring the Test Area. Measurements of shear strength by vane and static cone pene‐trometer, and bulk density by nuclear densitometer, were made in place from the submersible Deep Quest. Sixteen short (< 1.6 m) gravity cores were collected from ships.

The geotechnical properties show little areal variation and generally change uniformly with depth within the 55 km² Test Area. Silt is the predominant grain size, averaging about 62%. In‐place bulk density shows little change with increasing depth, values range from 1.23 to 1.26 Mg/m³; laboratory density values increase with depth, ranging from 1.30 to 1.52 Mg/m³ between the surface and a depth of about 1.1 m. The difference between the in place and laboratory values may indicate sampling densification of the cored sediment. Water content in the cores decreases uniformly within the range of 249 to 43% dry weight. Shear strength increases linearly with depth. The laboratory shear strength values are lower than the in place values, which range from 4 kPa at the surface to about 29 kPa at a depth of 3.27 m. Predictor equations relate Atterberg limits, bulk density, water content, and laboratory and in place shear strength to depth. Sedimentation‐compression e log p curves have an equivalent compression index of 1.5 to nearly 2. Excluding rurbidite layers and sampling disturbance effects, all cores indicate a uniform depositional environment in the surface to 1.6 m of sediment sampled. The geotechnical properties indicate that the sediments in the west central and southwest parts of the Test Area exhibit vertical heterogeneity due to thin silt‐sand layers, presumably of turbidity current origin, that originated from the Coronado Canyon.     

Ocean–wave coupled modeling in COAMPS-TC: A study of Hurricane Ivan (2004)

Tropical cyclone ocean–wave model interactions are examined using an ESMF – (Earth System Modeling Framework) based tropical cyclone (TC) version of the Coupled Ocean/Atmosphere Mesoscale Prediction System (COAMPS®¹). This study investigates Hurricane Ivan, which traversed the Gulf of Mexico (GOM) in September 2004. Several oceanic and wave observational data sets, including Acoustic Doppler Current Profilers (ADCPs), National Oceanic and Atmospheric Administration (NOAA) buoys, satellite altimeter data, and Scanning Radar Altimeter (SRA) data, allow for a unique analysis of the coupled atmosphere, ocean (Navy Coastal Ocean Model, NCOM), and wave (Simulating WAves Nearshore, SWAN) models in COAMPS-TC. To determine the feasibility of coupling NCOM to SWAN in high-wind conditions during Hurricane Ivan, near-surface currents in NCOM were first compared to near-surface ADCP observations. Recent modifications to SWAN, including new wind-to-wave energy input and wave-breaking energy dissipation source functions, as well as a new ocean surface drag coefficient formulation appropriate for high-wind conditions, significantly improved the forecast wave field properties, such as significant wave height (SWH), in TC conditions. Further results show that the ocean-to-wave model coupling, which allows for the strong, hurricane-induced, surface currents in NCOM to interact with SWAN, provided additional improvements to the forecast SWH field. Additionally, wave-to-ocean model coupling, which included the input of the Stokes Drift Current (SDC) calculated from the SWAN wave spectra to NCOM, is examined. The models indicate that the SDC was on the order of 10–25% of the near-surface Eulerian current during Ivan. Recent studies of the importance of the SDC and the resulting Langmuir turbulence on vertical ocean mixing in TCs is also discussed.     

Scale dependent dynamic capillary pressure effect for two-phase flow in porous media

Causes and effects of non-uniqueness in capillary pressure and saturation (P^c–S) relationship in porous media are of considerable concern to researchers of two-phase flow. In particular, a significant amounts of discussion have been generated regarding a parameter termed as dynamic coefficient (τ) which has been proposed for inclusion in the functional dependence of P^c–S relationship to quantify dynamic P^c and its relation with time derivative of saturation. While the dependence of the coefficient on fluid and porous media properties is less controversial, its relation to domain scale appears to be dependent on artefacts of experiments, mathematical models and the intra-domain averaging techniques. In an attempt to establish the reality of the scale dependency of the τ–S relationships, we carry out a series of well-defined laboratory experiments to determine τ–S relationships using three different sizes of cylindrical porous domains of silica sand. In this paper, we present our findings on the scale dependence of τ and its relation to high viscosity ratio (μ_r) silicone oil–water system, where μ_r is defined as the viscosity of non-wetting phase over that of the wetting phase. An order of magnitude increase in the value of τ was observed across various μ_r and domain scales. Also, an order of magnitude increase in τ is observed when τ at the top and the bottom sections in a domain are compared. Viscosity ratio and domain scales are found to have similar effects on the trend in τ–S relationship. We carry out a dimensional analysis of τ which shows how different variables, e.g., dimensionless τ and dimensionless domain volume (scale), may be correlated and provides a means to determine the influences of relevant variables on τ. A scaling relationship for τ was derived from the dimensionless analysis which was then validated against independent literature data. This showed that the τ–S relationships obtained from the literature and the scaling relationship match reasonably well.     

基于GRACE Follow-On卫星重力梯度法精确反演地球重力场

由于GRACE Follow-On双星系统等效于基线长为星间距离的一维水平重力梯度仪,因此本文基于GRACE Follow-On卫星重力梯度法开展了精确和快速反演下一代地球重力场的可行性论证研究. 研究结果表明：第一,基于GRACE Follow-On卫星重力梯度法（GFO-SGGM）,利用卫星轨道参数（轨道高度250 km、星间距离50 km、轨道倾角89°、轨道离心率0.001）、关键载荷测量精度（星间距离10^-6 m、星间速度10^-7 m·s^-1、星间加速度10^-10 m·s^-2、轨道位置10^-3 m、轨道速度10^-6 m·s^-1、非保守力10^-11 m·s^-2）、观测时间30天和采样间隔10 s反演了120阶地球重力场,在120阶处累计大地水准面精度为9.331×10^-4 m. 第二,在120阶内,利用将来GRACE Follow-On双星反演地球重力场精度较现有GRACE双星平均提高61倍,因此GRACE Follow-On卫星重力梯度法是进一步提高地球重力场反演精度的优选方法. 第三,下一代GRACE Follow-On计划较当前GRACE计划的优点如下：轨道高度更低（200~300 km）、载荷精度更高（10^-7 ~10^-9 m·s^-1）和星间距离更短（50~100 km）.