城乡差距的核心-边缘模型分析

将地区划分为城区和农村两区域系统,构建一个综合考虑城乡劳动力迁移、环境污染、农业生产效率、城乡贸易和公共服务基础设施建设等诸因素的核心-边缘模型,以深入系统地考察城乡差距问题,对于解决现有城乡问题有着重要的理论和现实意义.研究表明:劳动力向城区迁移有助于提高城镇和农村居民的生活效用水平,并缩小城乡差距;环境污染物排放对居民生活造成负面影响,生产活动的集聚对城乡差距的影响取决于污染的危害程度;倘若农业生产的环境影响较小,农业生产效率的提高可以缩小城乡差距;城乡间交通基础设施建设、城区交通及通信设施建设和产业集聚等将提高城镇居民效用水平,拉大城乡差距.     

An environmental decision‐support system for the management of water pollution in a tidal river network

This paper is about the development of a decision‐support system for water‐pollution management and environmental planning. More specifically, the paper first presents the overall concept and the system architecture of a generic environmental decision‐support system (EDSS) and then develops an EDSS especially for analysing the tidal flow pattern and water quality of China's Pearl River Delta. The EDSS developed here employs the object‐oriented approach to design the environmental database and utilizes the system integration technology to develop the overall user‐friendly system that operates in the Windows environment. Furthermore, the system can be expanded to facilitate automated model selection and analysis. The EDSS should be of value for managing water quality of river networks with complicated flow patterns, such as that found in the Pearl River Delta.     

漳州地热田基岩裂隙水系统温度分布特征

为研究漳州地热田基岩裂隙水系统温度分布特征,建立了新的三维基岩裂隙水系统概念模型,并利用Fluent软件求解模型。结果表明:基岩裂隙热水温度场受到断裂区的强烈控制,在北东—南西向断裂中,强烈对流形成的高温热柱刺穿了基岩顶部形成热田高温中心;基岩热流在断裂区中部高温区达到最大,在北东—南西方向上最大值为343.02mW/m2,在北西—南东方向最大值为368.72mW/m2,并向边缘逐渐降低;第四系孔隙水的存在和运动使得地表热流的最大值和局部值降低。未来漳州热田应加强深部温度的测量研究。     

末次盛冰期以来科尔沁沙地古气候变化及其边界重建

利用光释光测年技术,获得了覆盖科尔沁沙地内部及外围的20个风成沙-砂质古土壤沉积序列的年代.在分析前人研究的基础上,结合地层和气候代用指标重建了末次盛冰期以来科尔沁沙地的演化过程.结果表明:科尔沁沙地的气候变化和沙丘的固定与活化主要经历了4个阶段,即:26 ～ 12ka,气候极端干冷,沙地大面积活化;12.0 ～9.5ka,气候趋于暖湿,但仍比较干冷,沙地由大规模沙化向固定成壤过渡;9.5～2.5ka,气候暖湿,沙地基本固定;2.5ka以来,气候呈干冷与暖湿交替状态,沙地亦存在多次固定与活化,其中,从1.5ka开始,沙丘活化明显.基于风沙沉积序列的空间分布和光释光测年结果,末次盛冰期科尔沁沙地同时向南和北扩展:南至翁牛特-库伦旗一线,至少扩张了26km;北至霍林河一带,至少扩张了30km;东界受东辽河限制,与现代边界几乎一致.沙地面积较现代扩张了至少2.05×104km2,扩大了37.7％.全新世大暖期,沙丘大面积固定.研究表明,科尔沁沙地气候与环境演变受东亚季风影响,也是全球气候变化的区域响应.     

末次盛冰期和全新世大暖期呼伦贝尔沙地的环境变化

呼伦贝尔沙地保存的风沙层-古土壤沉积序列,是认识过去环境变化的重要地质记录.沙地沉积具有速率快、沉积与侵蚀并存的特点,因此,通过大量独立的光释光年代控制对不同的剖面进行拼接,可以重建沙地在千年尺度上干湿变化过程以及特征时期的边界.本文获得了呼伦贝尔沙地8个沉积剖面的47个光释光年代和近200个样品的环境代用指标数据,结合已发表文献资料,揭示了16ka以来呼伦贝尔沙地千年尺度的干湿变化,并估算了末次盛冰期(LGM)和全新世大暖期(HO)沙地流沙的边界.初步认为,LGM期间,呼伦贝尔沙地相对于现代沙带边界,最远向北移动了约60km,向东移动了约50km,并且南北沙带之间的区域全部沙化;LGM期间沙漠化面积达到22337km2,相对现代沙漠化面积扩大了约2.7倍.而在HO期间,整个沙地被植被所固定,发育砂质古土壤层,只在局部区域存在短暂的风沙活动.     

2008年以来荣昌地区地震重新定位及地震丛集原因初探

通过对荣昌地区地震重新定位,结合当地注水资料,对该地区2008年以来地震丛集的原因进行初步研究.收集了2007～2011年6月间荣昌台记录的131个远震,计算了这些地震的接收函数,用H-Kappa叠加方法得到台站下方及附近的莫霍面深度,并用线性反演方法反演了该区S波速度结构.利用接收函数反演得到的速度结构,采用双差定位方法对荣昌及其邻区2008 ～2011年8月间ML≥1.0地震进行了重新定位,得到了408个地震的精确位置.重定位结果显示地震的水平震中分布与华蓥山断裂走向一致,另外在通过2010年M4.7地震震中且垂直于华蓥山断裂的剖面中,地震分布所勾画的发震断层轮廓显示地震的发震断层倾向为SE,倾角约70°左右,这与华蓥山断裂的产状(50°∠75°)较为一致.分析了注水点与地震分布的空间关系及注水量与地震频度的关系,认为注水井位置距离2008年以来的几次4级地震震中较远,震源深度主要分布在6 ～ 7km,且注水量与地震频度的对应关系不显著,地震丛集性原因尚待更多研究.     

地磁Z分量日变形态畸变与周边低点位移异常关系初探

通过对2010年1月1日至2011年12月31日期间中国大陆地磁低点位移异常数据及蒙城地震台地磁垂直分量日变形态畸变统计,按低点位移分界线到蒙城地震台的距离,分段探讨该台地磁垂直分量日变形态畸变与其周边低点位移异常的关系.     

Sensitivity analysis of the probability distribution of groundwater level series based on information entropy

Information entropy is an effective method to analyze uncertainty in various processes. The principle of maximum entropy (POME) provides a guide line for the parameter estimation of probability density function (PDF). Mutual entropy analysis is well qualified for delineating the nonlinear and complex multivariable relationship. The probability distribution of model output is the element of model uncertainty analysis. In this paper, a synthetic groundwater flow field is build to produce groundwater level series (GLS). The probability distribution of GLS is obtained by the frequency analysis method based on POME and Chi-Squared test. The important uncertainty factors that affect the parameters of PDF of GLS are assessed by the sensitivity analysis methods, which include stepwise regression analysis and mutual entropy analysis. Results of this analysis indicate that most of the GLS follow normal distribution (or log-normal distribution), while a few obey others. The mean and variance of normal GLS are affected differently by the input variables of groundwater model. Mutual entropy analysis is more competitive and appropriate for delineating the nonlinear and nonmonotonic multivariable relationship than stepwise regression analysis.     

Tomographic velocity inversion for ADCIGs in areas with a rugged surface

Pre-stack depth migration velocity analysis is one of the key techniques influencing image quality. As for areas with a rugged surface and complex subsurface, conventional prestack depth migration velocity analysis corrects the rugged surface to a known datum or designed surface velocity model on which to perform migration and update the velocity. We propose a rugged surface tomographic velocity inversion method based on angle-domain common image gathers by which the velocity field can be updated directly from the rugged surface without static correction for pre-stack data and improve inversion precision and efficiency. First, we introduce a method to acquire angle-domain common image gathers (ADCIGs) in rugged surface areas and then perform rugged surface tomographic velocity inversion. Tests with model and field data prove the method to be correct and effective.