基于重力全张量数据的Parker-Oldenburg算法研究     

卢鹏羽  马国庆 《世界地质》2016,35(1):216-222

相比重力数据,重力张量数据通常包含更多的异常信息。本文根据重力数据与重力张量数据的关系,利用位场转化技术,将重力张量数据应用于传统的Parker-Oldenburg密度界面反演算法中。通过模型试验,证明了在网格间距较大或者数据存在一定噪音时,使用本文算法进行反演能得到更好的效果。实验结果说明利用重力张量数据可以有效地提高密度界面反演的分辨率。  相似文献   

宁波市地下空间开发利用地质环境制约因素研究   总被引：1，自引：0，他引：1  

吴炳华  蔡国成  潘小青  陈沈健 《城市地质》2016,(4)

地质环境条件是制约地下空间开发利用的最基本因素,只有正确认识地下空间开发对地质环境的影响,才能避免地下空间利用中产生的各种不利后果。基于对宁波市地质环境背景条件的认识,分别从水文地质条件、工程地质条件和环境地质问题等三个方面,研究了地下空间开发利用的影响因素。研究结果表明,水文地质条件的制约因素有孔隙潜水位埋深、含水层厚度、岩土层透水性能和基坑突涌可能性等;工程地质条件的制约因素有软土厚度、人工填土厚度、土质均匀性和地层组合等;主要环境地质问题为地面沉降和浅层天然气影响等。通过本次研究,为宁波市地下空间开发利用地质环境适宜性评价奠定了基础,为宁波市地下空间的合理开发利用提供了技术支撑。  相似文献   

宁波市地下空间开发利用地质环境适宜性评价   总被引：1，自引：0，他引：1  

赵团芝  侯艳声  胡新锋 《城市地质》2016,(4):88-93

随着城市化建设快速推进,地下空间资源开发是解决城市土地资源紧张的合理途径,而地质环境适宜性评价对地下空间的开发利用具有至关重要的作用。本文分析了城市地下空间开发利用地质环境适宜性评价的影响因素,运用层次分析法确定岩土体特征、水文地质条件、环境地质问题、技术经济等指标因素的权重,建立模糊综合评价模型,定量评价宁波东部新城浅层(-15~0m)和中层(-30~-15m)的地下空间开发利用地质环境适宜程度。评价结果显示,东部新城地下空间开发地质环境适宜性等级分为Ⅱ级较适宜和Ⅲ级较不适宜,并根据不同的适宜等级提出了地下空间开发利用方式,为宁波东部新城的地下空间开发利用提供依据。  相似文献   

Stability and capsizing analysis of nonlinear ship rolling in wind and stochastic beam seas     

《Applied Ocean Research》2016

Considering the actual seaway condition, stability and capsizing of nonlinear ship rolling system in stochastic beam seas is of significant importance for voyage safety. Safe zone are defined in the phase space plan of the unperturbed Hamilton system to qualitatively distinguish ship motions as capsize and noncapsize. Capsize events are defined by solutions passing out of the safe zone. The probability of such an occurrence is studied by virtue of the random Melnikov function and the concept of phase space flux. In this paper, besides conventional wave excitation, the effect of wind load is also taken into account. The introduction of wind load will lead to asymmetry, in other words, it transforms the symmetric heteroclinic orbits into asymmetric homoclinic orbits. For asymmetric dynamical system, the orbital analytic solutions and its power spectrum are not readily available, and the technique of discrete time Fourier transformation (DTFT) is used. In the end, as verification of theoretical critical significant wave height, capsizing probability contour diagram is generated by means of numerical simulation. The contour diagram shows that these analytical methods provide reliable and predictive results about the likelihood of a vessel capsizing in a given seaway condition.  相似文献   

A Method for Automatically Selecting Aids to Navigation Based on their Spatial Influence Domains     

Lihua Zhang  Sipeng Li  Shuaidong Jia 《Marine Geodesy》2016,39(3-4):256-270

To address the limitations of manually selecting aids to navigation (AtNs) on charts, a method for automatically selecting AtNs based on their spatial influence domains (SIDs) is proposed. First, the associations between the spatial attributes of an AtN are analyzed. Second, an SID of the AtN is defined, and a model of the SID is constructed based on the associations between the spatial attributes. Third, the importance of the location of the AtN is weighted based on the SID model. Fourth, an algorithm to automatically select AtNs based on the maximum coverage of the SIDS of preselected AtNs is developed. Finally, several AtNs are selected automatically using the algorithm. The experimental results demonstrate that (1) the proposed method can automatically select AtNs and the results comply with the requirements; (2) the automatic selection can eliminate the human-induced errors or the inconsistent results of manual selections from different operators; and (3) the efficiency of the proposed method is higher than that of current manual methods.  相似文献   

高阶边界元方法求解规则波在三维局部渗透海床上的传播     

章旭  勾莹  倪云林  滕斌  刘珍 《海洋学报》2016,38(1):133-142

基于线性势流理论,利用高阶边界元法研究了规则波在三维局部渗透海床上的传播。根据Darcy渗透定律推导出渗透海床的控制方程,利用渗透海床顶部和海底处法向速度和压强连续条件得到渗透海床顶部满足的边界条件。根据绕射理论,利用满足自由水面条件的格林函数建立了求解渗透海床绕射势的边界积分方程,采用高阶边界元方法求解边界积分方程进而得到自由水面的绕射势和波浪在局部渗透海床上传播过程中幅值的变化情况。通过与已发表的波浪对圆柱形暗礁的时域全绕射结果对比,证明了本文建立的频域方法计算波幅的正确性和有效性。利用这一模型研究了三维矩形渗透海床区域上波浪的传播特性,并分析了入射波波长、海床渗透特性系数等参数对波浪传播的影响。  相似文献   

Vast amount of accommodation space controlled evolution of a continuous Pliocene–Pleistocene mixed cool-water carbonate-siliciclastic prograding wedge in the Bay of Oran (Western Mediterranean)     

《Marine and Petroleum Geology》2016

The Bay of Oran is part of the northern Algerian continental margin, located in the Western Mediterranean Sea between Europe and northern Africa. A regional terrace in ca. 320 m water depth described in earlier studies and a second deeper located one (∼1200 m water depth) provide an unusually vast amount of accommodation space for an observed prograding wedge. Seismo-stratigraphic interpretation of high-resolution reflection seismic data show different phases of mixed cool-water carbonate-siliciclastic deposition: (Ia) Initial aggradation with low dipping foreset deposition during early-Pliocene relative sea-level highstand. (Ib) Deposition transitions to progradation when aggradation reaches the base level. (IIa) Once progradation reaches the shelf break, terrace deposition is reduced to coarse fraction foreset deposits until it ceases entirely. (IIb) Finer sediments are bypassed and start to aggrade on the lower slope terrace until deposits reach the shelf terrace depth. (III) Due to accommodation space prolongation progradation recommences. Phase IIa and phase III deposits are separated by a hiatus. A drop in mean sea-level during the mid-Pleistocene will have caused the base level to fall below the upper strata, hence causing some reworking and redeposition. However, sea-level variations are not considered to be a main controlling factor of the depositional sequences. The evolution of this continuous Pliocene–Pleistocene mixed cool-water carbonate-siliciclastic prograding wedge is instead attributed to the controlling factor of this unusually vast amount of accommodation space. In closest proximity to the sea-floor, sparse recent sedimentation in form of 5–10 m thick sediment lobes can be observed in subbottom profiler data only. From a tectonic point of view, a prolongation of the Yusuf Fault into the survey area though expected by other authors could not be supported with the available dataset.  相似文献   

Uncertainty analysis of space–time prisms based on the moment-design method     

Yee Leung  Zi Zhao  Jiang-Hong Ma 《International journal of geographical information science》2016,30(7):1336-1358

Space–time prism (STP) is an important concept for the modeling of object movements in space and time. An STP can be conceptualized as the result of the potential path of a moving object revolving around in the three-dimensional space. Though the concept has found applications in time geography, research on the analysis and propagation of uncertainty in STPs, particularly under high degree of nonlinearity, is scanty. Based on the efficiency and effectiveness of the moment-design (M-D) method, this paper proposes an approach to deal with nonlinear error propagation problems in the potential path areas (PPAs) of STPs and their intersections. Propagation of errors to the PPA and its boundary, and to the intersection of two PPAs is investigated. Performance of the proposed method is evaluated via a series of experimental studies. In comparison with the Monte Carlo method and the implicit function method, simulation results show the advantages of the M-D method in the analysis of error propagation in STPs.  相似文献   

临沂市城市地下空间资源地质调查评价研究          下载免费PDF全文

杨明  朱成河  郭长胜  杨月 《山东国土资源》2016,32(3)

临沂市城市建设发展迅速,城市面貌日新月异,但高楼密集、交通拥挤等问题也逐渐显现出来,城市建设需要更多的空间,开发利用城市地下空间已是首要解决的问题。临沂市位于沂沭断裂带与临沂单斜、平邑-方城盆地多个地质单元的交会处,断裂构造发育,地震活动强烈,地质条件复杂,城市地下空间开发的影响因素众多,该文从水文及水文地质条件、工程地质条件、环境地质条件、人类工程活动等方面对临沂城市地下空间资源地质环境适宜性进行了分析研究,提出了其主要制约因素为极其发育的活动性断裂的看法,凡是活动性断裂对地下空间开发有影响的区域,均为地下空间资源开发制约区。评价结论对于提高城市发展格局、提高城市空间利用率、指导城市空间开发利用规划具有一定的参考意义。  相似文献   

应用两次展开法求解系泊柱体慢漂运动方程     

金瑞佳  滕斌  吕林 《海洋工程》2016,34(5):11-19

在深海中系泊的海洋平台,如Spar平台,水下部分为带有系泊的圆柱结构,其水平方向运动响应往往具有较低的自振频率,容易在低频波浪力(源于非线性的差频效应)作用下发生共振响应,使结构发生大幅水平慢漂。当浮体的瞬时位置大幅偏离初始位置时,基于初始平衡位置的摄动展开法会存在较大误差。针对这一问题,采用两次展开方法,对大幅慢漂运动开展时域模拟研究。对双色波作用下自由漂浮圆柱的大幅运动响应问题进行数值分析,并与采用基于初始平衡位置的摄动展开法的计算结果进行了对比。结果表明,采用新的两次展开法可以计算出波浪遭遇频率的变化和波浪漂移阻尼,而这无法从基于初始平衡位置的常规摄动展开法中得到,体现了两次展开法在分析大幅慢漂问题上的优势。  相似文献