广州市社区出行低碳指数格局及其影响因素的空间异质性

通过构建社区出行低碳指数（CTLCI）模型,对广州市社区出行低碳指数的空间格局及其差异特征进行了分析,并利用全局回归（OLS）模型和地理加权回归（GWR）模型对社区出行低碳指数的影响因素以及其间关系的空间异质性进行了研究。结果表明,广州市社区出行低碳指数由中心城区向外逐渐递增,呈明显的圈层结构。内圈层的社区出行低碳指数内部差异最小,中间过渡圈层的最大。社区人口密度对社区出行低碳指数的影响以正向作用为主,公共交通供给水平和路网密集程度对社区出行低碳指数的影响以负向作用为主,且它们的影响作用具有空间异质性。具体指出了在不同地域空间内社区人口密度、公共交通供给水平和路网密集程度对社区出行低碳指数在影响程度和作用方向上的差异,为减少广州城市交通碳排放、针对不同空间制定有效的低碳政策和构建低碳城市空间结构提供了科学依据。     

近海欠密实砂质海床内波致渐进液化特征研究

利用一个经过广泛验证的数值模型FSSI-CAS 2D为计算工具,采用砂土的高级本构模型Pastor-Zienkiewicz-Mark III (PZIII) 描述海床砂土的动态力学行为,定量研究松散海床地基土在波浪作用下,其内部的液化过程和特征,以加深对波致海床液化特征、性质的认识。计算结果分析表明,开发的耦合数值模型FSSI-CAS 2D能够很好地捕捉到波浪作用下欠密实海床的动力响应特征,以及海床内的累积液化过程等一些列的非线性物理现象。研究表明,波浪导致的松砂海床液化是一个渐进过程,海床表面首先液化,并逐渐向下扩展。     

低渗透油藏CO2驱油开发方式与应用

CO₂驱是一种能大幅度提高原油采收率的三次采油技术,国内该项技术的研究和应用起步较晚,多以先导试验为主。苏北盆地溱潼凹陷经过10余年的探索,已经在5个低渗油田开展了CO₂驱先导试验和推广应用,针对这5个油藏利用一维细管模拟和油藏数值模拟方法开展了注气时机、段塞尺寸和注气部位的研究,并应用典型实例进行了分析,认为先期注入提高混相压力,可更有效地缩短两相区过渡带,增加油相中溶解的CO₂含量,降低油相粘度和油气界面张力,进而提高混相程度,更有利于驱油;采用大尺寸段塞可加大CO₂波及区域,较好地保持地层能量,从而提高油井见效率,增强驱替效果;高部位注气可有效地抑制重力超覆,减少CO₂气体过早地产出和突破的机会。就苏北盆地低渗油藏而言,采用先期注入、大尺寸段塞和高部位注气不失为一种成熟有效的提高采收率方法。     

基于SVD和BRD的二维核磁共振测井正则化反演算法研究

二维核磁共振能从"弛豫-扩散"两个维度上展现流体性质,在识别稠油储层方面具有理论优势,是当前核磁共振测井技术的研究热点.本文深入研究二维核磁共振测井原理,系统分析CPMG-DE脉冲序列测量扩散系数与弛豫时间的方法,结合核磁共振二维谱数理模型,提出一种基于SVD和BRD的正则化反演算法.该算法通过SVD压缩数据,采用带非负约束的Tikhonov正则化方法求解流体"弛豫-扩散"分布,并基于BRD算法迭代确定最佳正则化因子.模拟实验与数值分析表明,该算法无需先验信息、运算效率高、相对误差小,在原始数据信噪比低至50时,仍可有效获取流体(T₂,D)二维分布.在二维核磁共振测井数据实时解释应用中,该方法较传统反演算法(如TSVD)具有较大优势.同时,在自主研发的核磁共振测井仪测量CuSO₄溶液(T₂,D)分布的实验显示,本文设计算法对弛豫时间和扩散系数的反演误差分别仅为2%和4%,较TSVD算法有较大改善.     

Delineation of the northern limit of the Congo Craton based on spectral analysis and 2.5D modeling of aeromagnetic data in the Akonolinga-Mbama area,Cameroon

Aeromagnetic data of the Akonolinga-Mbama region are analyzed in order to elucidate the subsurface geology of the area. The available data in the form of a residual aeromagnetic map is interpreted as a vast magnetically quiet region, and complex zones which do not correlate with the surface geology of the region.Within the magnetically quiet zone, a high negative circular elongated anomaly zone seems to represent an intrusion of a plutonic rock into the metamorphic formations of the region. Spectral analysis and two-and-a-half dimensional (2½-D) modeling are used to estimate the depth of the causative bodies and determine the source rocks along three profiles crossing the suspected areas. Models from various zones of granitic intrusions are obtained, thereby proposing some shallow fault lines along zones of contact. This permits us to mark out the northern margin of the Congo Craton, thus enabling us to distinguish the cratonic formations from the Pan African fold belt. Part of the belt has been thrust over the northern portion of the Congo Craton in Cameroon.     

Application of diffracted wave analysis to time‐lapse seismic data for CO2 leakage detection

Time‐lapse seismic analysis is utilized in CO₂ geosequestration to verify the CO₂ containment within a reservoir. A major risk associated with geosequestration is a possible leakage of CO₂ from the storage formation into overlaying formations. To mitigate this risk, the deployment of carbon capture and storage projects requires fast and reliable detection of relatively small volumes of CO₂ outside the storage formation. To do this, it is necessary to predict typical seepage scenarios and improve subsurface seepage detection methods. In this work we present a technique for CO₂ monitoring based on the detection of diffracted waves in time‐lapse seismic data. In the case of CO₂ seepage, the migrating plume might form small secondary accumulations that would produce diffracted, rather than reflected waves. From time‐lapse data analysis, we are able to separate the diffracted waves from the predominant reflections in order to image the small CO₂ plumes. To explore possibilities to detect relatively small amounts of CO₂, we performed synthetic time‐lapse seismic modelling based on the Cooperative Research Centre for Greenhouse Gas Technologies (CO2CRC) Otway project data. The detection method is based on defining the CO₂ location by measuring the coherency of the signal along diffraction offset‐traveltime curves. The technique is applied to a time‐lapse stacked section using a stacking velocity to construct offset‐traveltime curves. Given the amount of noise found in the surface seismic data, the predicted minimum detectable amount of CO₂ is 1000–2000 tonnes. This method was also applied to real data obtained from a time‐lapse seismic physical model. The use of diffractions rather than reflections for monitoring small amounts of CO₂ can enhance the capability of subsurface monitoring in CO₂ geosequestration projects.     

Possible change in distribution of seaweed, Sargassum horneri, in northeast Asia under A2 scenario of global warming and consequent effect on some fish

Global warming effects on seaweed beds are already perceptible. Their geographical distributions greatly depend on water temperatures. To predict future geographical distributions of brown alga, Sargassum horneri, forming large beds in the northwestern Pacific, we referred to future monthly surface water temperatures at about 1.1° of longitude and 0.6° of latitude in February and August in 2050 and 2100 simulated by 12 organizations under an A2 scenario of global warming. The southern limit of S. horneri distribution is expected to keep moving northward such that it may broadly disappear from Honshu Island, the Chinese coast, and Korean Peninsula in 2100, when tropical Sargassum species such as Sargassum tenuifolium may not completely replace S. horneri. Thus, their forests in 2100 do not substitute those of S. horneri in 2000. Fishes using the beds and seaweed rafts consisting of S. horneri in East China Sea suffer these disappearances.     

iTRAQ-based proteomic profiling of the marine medaka (Oryzias melastigma) gonad exposed to BDE-47

A recent study demonstrated that 2,2′,4,4′-tetrabromodiphenyl ether (BDE-47) may have an adverse effect on the reproduction in marine medaka (Oryzias melastigma), but the molecular mechanisms remain largely unknown. In this study, we investigated the protein expression profiles of male and female gonads of O. melastigma exposed to dietary BDE-47 at two dosages (0.65 and 1.30 μg/g/day, respectively) for 21 days. Extracted proteins were labeled with iTRAQ and analyzed on a MALDI TOF/TOF analyzer, as results, 133 and 144 unique proteins were identified in testis and ovary, respective, and they exerted dose- and sex-dependent expression patterns. In testis, among the 42 differentially expressed proteins; down-regulation of histone variants and parvalbumins implicated BDE-47 may disrupt the spermatogenesis and induce sterility in fishes. In ovary, 38 proteins were differentially expressed; the elevation of vitellogenins and apolipoprotein A–I expression indicated BDE-47 acts as an estrogen-mimicking compound and led to reproductive impairment in O. melastigma.     

Magnetic evidence of a crustal fault affecting a linear laccolith: The Guadiana Fault and the Monchique Alkaline Complex (SW Iberian Peninsula)

Magnetic anomalies can help reveal the structure of the upper crust in regions with intermediate or basic igneous rocks, and their continuity is essential to determine the position of crustal faults. The southwestern Iberian Peninsula constitutes the foreland of the Betic Cordillera and is characterized by an elongated E-W dipole extending 200 km toward its external zones. The anomaly is related to the outcropping Monchique Alkaline Complex, characterized by rocks of moderate magnetic susceptibility (0.029 SI) intruding into the metapelitic host rock of the South Portuguese Zone. Analysis of aeromagnetic and field magnetic anomalies serves to constrain the geometry of this laccolith. Toward the east, the magnetic dipole has a 60 km long N-S sharp boundary that coincides with the southern part of the Guadiana River. Field magnetic and gravity anomalies confirm the presence of this structure. It is produced by a sharp step in the elongated anomalous body, with an E downthrown block, interpreted as the offset produced by a deep N-S crustal fault—the Guadiana Fault. Therefore, the Guadiana River has three long linear segments near its mouth, locally coinciding with a N-S trending joint set, that support the presence of this major fault. To date, no evidence of this tectonic discontinuity, coinciding with the Spanish-Portuguese border, has been reported. Magnetic research is essential for understanding the structure of wide regions intruded by intermediate and/or basic igneous rocks.     

State estimation of tidal hydrodynamics using ensemble Kalman filter

This paper presents a coupling of an ensemble Kalman filter (EnKF) with a discontinuous Galerkin-based, two-dimensional circulation model (DG ADCIRC-2DDI) to improve the state estimation of tidal hydrodynamics including water surface elevations and depth-integrated velocities. The methodology in this paper using EnKF perturbs the modeled hydrodynamics and bottom friction parameterization in the model while assimilating data with inherent error, and demonstrates a capability to apply EnKF within DG ADCIRC-2DDI for data assimilation. Parallel code development presents a unique aspect of the approach taken and is briefly described in the paper, followed by an application to a real estuarine system, the lower St. Johns River in north Florida, for the state estimation of tidal hydrodynamics. To test the value of gauge observations for improving state estimation, a tide modeling case study is performed for the lower St. Johns River successively using one of the four available tide gauging stations in model-data comparison. The results are improved simulations of water surface elevations and depth-integrated velocities using DG ADCIRC-2DDI with EnKF, both locally where data are available and non-locally where data are not available. The methodology, in general, is extensible to other modeling and data applications, for example, the use of remote sensing data, and specifically, can be readily applied as is to study other tidal systems.