闲暇时间约束对中山陵景区国内客源市场空间结构的影响

闲暇时间是旅游需求得以实现的必要条件之一,居民闲暇时间的变化必然对旅游地客源市场空间结构产生影响。选择"五一"小长假、"十一"黄金周及暑假3类6个不同闲暇时长的时段,基于现场问卷调研,使用客源地地理集中指数、客源吸引半径、距离衰减曲线及引力模型研究闲暇时间约束对南京市中山陵景区客源市场空间结构的影响,发现随着假日时长的增加,居民出游距离受闲暇时间的约束降低,从而旅游地客源吸引半径增大,客源地集中指数降低、距离衰减曲线变缓、距离衰减指数降低。研究结果表明,在不同时长的闲暇时间约束下,距离因素对景区客流量的影响最大,其次为收入(客源地人均地区生产总值),而客源地人口规模因素的影响最小。     

山东蓬莱大黑山岛碱性火山岩地球化学特征

庙岛群岛中的大黑山岛出露碱性火山岩,对研究壳-幔过程及黄、渤海演化具重要意义。文中作者对大黑山岛火山岩的常、微量元素、K-Ar年龄及Nd-Sr-Pb同位素体系进行测试确定。结果表明,岩石属钠质碱性玄武岩系列,岩浆岩喷发可分为8Ma前和8Ma后两个阶段;岩石常量元素含量除K2O、Na2O外差异小;随着火山岩的演化,岩浆源区深度变大;大黑山火山岩Nd-Sr-Pb同位素比值与夏威夷洋岛玄武岩相似,其岩浆的地幔端元组分为PREMA DM,又以PREMA为主,并有MORB物质混入。     

重磁异常正反演可视化实时方法技术改进

摘 要 给出了2∙5D 多边形截面棱柱体重磁异常的简化表达式及其偏导数;提供了实用的可 视化模型建立、修改、实时正反演中的一些具体方法技术。借助这一操作方便、功能强大的 图形化实时反演系统‚资料解释工作者可以综合利用各种地质资料对计算过程实现引导和控 制‚使其解释思想及技术方案得到充分体现‚从而提高计算速度和质量。     

Suppressing non‐Gaussian noises with scaled receiver wavefield for reverse‐time migration: comparison of different approaches

Numerical implementation of the gradient of the cost function in a gradient‐based full‐ waveform inversion (FWI) is essentially a migration operator used in wave equation migration. In FWI, minimizing different data residual norms results in different weighting strategies of data residuals at receiver locations prior to back‐propagation into the medium. In this paper, we propose different scaling methods to the receiver wavefield and compare their performances. Using time‐domain reverse‐time migration (RTM), we show that compared to conventional algorithms, this type of scaling is able to significantly suppress non‐Gaussian noise, i.e., outliers. Our tests also show that scaling by its absolute norm produces better results than other approaches.     

Seasonally Hypersaline Estuaries in Mediterranean-climate Regions

Data collected in three Californian estuaries indicate that hypersaline conditions exist during the dry summers typical of a Mediterranean climate. The generalised seasonal and longitudinal hydrographic structures are described and explained. It is argued that this seasonal hypersalinity is common and that it represents a major class of estuaries. The observed accumulation of salt indicates surprisingly long residence times in small basins which have free exchange with the ocean. This semi-isolation of the inner basin leads to a large build-up or severe depletion of nutrients, pollutants and plankton in these systems. Of concern are the trends to increase pollutant loading in the same systems that are experiencing an increase in residence times owing to freshwater extraction in the watershed.     

攀西地区月降水时序非线性特性分析

在介绍相空间重构理论的基础上,以攀西地区4个站点47 a的月降水时间序列为例,研究了该地月降水时间序列的非线性特性。首先,运用定量的G-P关联维方法,探讨了非线性分析的主要定量指标,具体而言有,饱和关联维数D2和柯尔莫哥诺夫熵,计算表明攀西月降水时间序列具有一定的非线性混沌特性。其次,结合定性的功率谱分析方法,进一步验证了攀西月降水时序具有非线性特性。除此之外还应用Cao方法检验,从而排除了月降水时序为随机序列的可能性。本文为进一步研究月降水时序数据的复杂性及其演化规律奠定了基础。     

A stability analysis of a conduit flow model for lava dome eruptions

Periodic variations in magma discharge rate and ground deformation have been commonly observed during lava dome eruptions. We performed a stability analysis of a conduit flow model by Barmin et al. [Barmin, A., Melnik, O., Sparks, R.S.J., 2002. Periodic behavior in lava dome eruptions. Earth and Planetary Science Letters 199 (1-2), 173–184], in which the periodic variations in magma flow rate and chamber pressure are reproduced as a result of the temporal and spatial changes of the magma viscosity controlled by the kinetics of crystallization. The model is reduced to a dynamical system where the time derivatives of the magma flow rate (dQ/dt) and the chamber pressure (dP/dt) are functions of Q and P evaluated at a shifted time t − t_?. Here, the time delay t_? represents the time for the viscosity of fluid particle to increase in a conduit. The dynamical system with time delay is approximated by a simple two-dimensional dynamical system of Q and P where t_? is given as a parameter. The results of our linear stability analyses for these dynamical systems indicate that the transition from steady to periodic flow depends on nonlinearities in the steady state relation between Q and P. The steady state relation shows a sigmoidal curve in Q − P phase plane; its slope has negative values at intermediate flow rates. The steady state solutions become unstable, and hence P and Q oscillate periodically, when the negative slope of the steady state relation ([dP/dQ]_S) exceeds a critical value; that is [dP/dQ]_S < − t_?γ/(2V_ch), where V_ch is the chamber volume and γ is an elastic constant which is related to the rigidity of chamber wall. We also found that the period and the pattern of oscillation of the conduit flow primarily depend on a quantity defined by LV_ch/r⁴, where L is the conduit length and r is the conduit radius.     

聚合物驱组合段塞分注实验研究

萨尔图油田南二区东部140号断层以东地区葡11—4油层,以多段多韵律和正韵律沉积为主,平均孔隙度30．0％,平均空气渗透率1980×10^-3μm2。水驱结束时该油层平均含水92％,采出程度39．5％。计划对该区块实施聚合物驱开采。以往经验认为,组合段塞调整注聚技术能够有效改善流度控制作用。然而对组合注入情况下如何进一步提高驱油效果、注入井分注时机、层段注入强度对开发效果有何影响却很少探讨。通过室内驱油实验,在聚驱的组合段塞注入不同时机（水驱空白阶段、含水下降阶段、含水稳定阶段、含水回升阶段）下调整注入强度实施分注以及在含水回升分注基础上进一步调整注入强度,同时对比不分注实验,评价各方案驱油效果。实验表明：不实施分注时聚驱采收率在水驱基础上提高了19．07个百分点,而组合段塞注入时实施分注均能够在不分注基础上进一步提高驱油效果;空白水驱时实施分注采收率提高幅度最大,为26．55个百分点;随着分注时机的滞后采收率提高幅度增加值依次递减,分注时机越早越好。     

关于GeoMedia Professional坐标系统定义问题的探讨

介绍了GeoMedia Professional软件在油田地面工程数字化工作中的应用,并针对设置工作空间、数据库、特征类的坐标系统时容易混淆的问题,及该问题引起的不同数据库之间的坐标系统不一致,以及一个数据库中个别特征类的坐标系统参数不正确的情况进行了分析,同时总结了操作过程中需要注意的问题及解决方法。     

GPS坐标向国家坐标转换的三维分离回归法

三维分离回归法是一种简单、有效、实用的转换方法,该方法可有效地克服病态矩阵问题。同时,为切实、有效地提高三维分离回归法的转换精度,计算时引入了三向尺度因子,使得三维转换参数由传统的7个变为现在的9个。详细介绍了三维分离回归法的基本原理、转换过程及转换实例。