加权总体最小二乘的效率优化算法

加权总体最小二乘法是理论上估计EIV模型参数相对严密的方法,其迭代过程中涉及的矩阵运算较为耗时,在处理大量级数据时尤其明显。PEIV模型有助于提高加权总体最小二乘法的计算效率。本文基于PEIV模型和经典最小二乘准则给出了一种加权总体最小二乘法算法,算法的推导过程简洁,易于理解,迭代过程中无需重构矩阵,减少了矩阵运算量。最后通过仿真试验验证了算法的可靠性。试验结果表明,本文算法可以取得与现有算法相同的参数估计精度且计算效率更高。     

黔江台水管仪与垂直摆预报效能对比分析

水管仪与垂直摆均是通过观测地倾斜变化来捕捉地震前兆信息的定点形变仪器,但因工作原理和观测频段不同,其观测结果和异常形态具有一定差异性。因此,对两种仪器的不同异常形态进行预报效能评估具有重要意义。利用异常自动化处理软件,提取黔江台倾斜仪各测项趋势转折、速率变化、破年变和潮汐因子等常见异常,并结合区域范围内的地震,对不同异常进行R值评分,评估不同测项的预报效能。结果显示：垂直摆NS分量预报效能最高,其趋势转折异常和M2潮汐因子异常均具有较好的预报指示意义;两套仪器的EW分量分别在破年变和速率变化预报效能较高;而水管仪NS分量预报效能最差,可能与该测项仪器故障频繁有关。此外,不同测项的异常对应的地震分布也具有一定的规律性。     

基于扇形筛选法的矢量数据压缩方法

针对具有预测功能的矢量数据压缩方法效率低下的问题,提出一种基于扇形筛选法的矢量数据压缩方法。在预测区域内利用扇形筛选法,能显著减少待选点,从而提高压缩效率。实验结果证明,该方法的效率与改进前方法相比提升了30%~40%。此外,与传统的Douglas-Peucker算法相比,该方法在相同阈值下可以得到更大的压缩比,且在较小阈值下具有更高的计算效率。     

基于航测的珠三角气溶胶垂直分布及活化特性

2017年9月14—27日在珠江三角洲地区开展了6个架次飞机观测试验。利用飞行获取的气溶胶、云凝结核、云滴及常规气象探头观测资料,结合天气形势、气象条件及气团后向轨迹分析,研究了珠江三角洲地区深圳气溶胶数浓度及其谱的垂直分布特征,配合不同过饱和度条件下云凝结核浓度观测,分析了气溶胶活化特性。结果表明：在不同天气条件下,深圳低层气溶胶数浓度变化范围为500~9000 cm-3;边界层内气溶胶分布相对均匀,谱型随高度变化与气象条件相关。将6个架次气溶胶观测资料根据数浓度及谱型分为3种类型：类型Ⅰ为海洋型气溶胶,数浓度小,粒子尺度大,谱型呈双峰分布;类型Ⅲ为大陆型气溶胶,数浓度高,粒子尺度小,谱宽较宽且呈三峰分布;类型Ⅱ为海洋大陆影响型气溶胶,即受海洋和大陆共同影响,数浓度低于类型Ⅲ高于类型Ⅰ,谱型为双峰分布。拟合了包含海洋型及大陆型气溶胶的3个架次近地面云凝结核活化谱,计算了气溶胶在不同过饱和度条件下的活化效率。     

提高任意广角波动方程计算效率及压制倏逝波干扰方法

任意广角波动方程（Arbitrarily Wide-angle Wave Equation,AWWE）是一种高精度的时空域单程波动方程,与其他时空域单程波方程相比,具有更大的成像倾角,因此是偏移成像的有力工具之一.本文改进了现有的AWWE有限差分计算方案,避免了原计算方案中对矩阵反复求逆的过程,同时减少了矩阵相乘的次数,显著地提高了AWWE数值计算的效率.数值实验证实,采用改进之后的计算方案,其计算结果与原方案完全一致.此外,本文采用了一种方法,在有倏逝波干扰的情况下,能在频率-波数（f-k）域区分出倏逝波与非倏逝波,为设计f-k滤波器提供合理的视速度门槛信息.偏移实验证实,在深度延拓时仅仅进行数次f-k滤波就能很好地抑制倏逝波干扰,提高偏移成像质量.     

地震波动方程的局部间断有限元方法数值模拟

近年来,随着地震波数值模拟对计算精度和效率的要求越来越高,间断有限元方法开始受到越来越多的关注.本文中,针对具有吸收边界条件的二维地震声波波动方程,作者提出了一种基于局部间断有限元方法的数值模拟算法.该算法在空间上使用局部间断有限元方法进行离散,在时间上采用了显式蛙跳格式.在这种时空离散的组合方式下,每个时间步上,此算法在空间剖分的每个单元上的求解计算是相互独立的,因而具有极高的并行性.通过数值算例,我们将该算法与连续有限元方法进行了比较.结果表明,本算法不仅具有对起伏构造的良好适应性,而且在计算效率和计算精度等方面,都具有优越性.     

基于砂箱物理模拟的断层封闭有效性评价新方法

泥岩涂抹的连续性影响油气跨断层运移,在相似岩性、相似应力条件下,泥岩厚度和断距长度是影响泥岩涂抹连续性的主要因素.本文结合岩芯观察,借助三维定量物理模拟实验对泥岩涂抹的连续有效性进行了研究.结果表明:①泥岩有效涂抹是决定断层封闭性的必要条件,涂抹连续厚度是封闭性评价的重要参数;②受剪切作用在断层带中形成连续的泥岩涂抹油...     

新疆公共服务资源空间配置与城乡互动耦合协调发展评价

公共服务资源是社会发展的"先行资本",对于区域社会经济发展与城乡融合发展具有正面外部效应。依据公共服务资源公平性、效益性与协调性原则,结合AHP、熵值与聚类分析方法,建立新疆公共服务资源配置与城乡互动效益评价指标体系,利用协调耦合发展模型,揭示研究区公共服务、城乡互动发展以及两者耦合协调度的总体特征和空间特征。结果表明:(1)新疆各地不同类型公共服务资源空间配置公平性有所差异,空间非公平性>人口非公平性。(2)公共服务资源综合效益以及城乡互动发展水平呈现较低、一般(中等)、较高三个类型。(3)公共服务效益空间分异特征呈现出东南片区>西北片区;城乡互动水平空间差异呈现出天山北坡经济带高于其他区域。(4)新疆大部分处于城乡互动与公共服务相互影响、相互磨合的过渡发展阶段,导致公共服务损益或城乡互动损益,个别区域处在两个系统相互制约、失调衰退阶段。通过进一步提出加快建立健全城乡互动公共服务体系,构建大、中、小多层次城镇空间格局,继续完善和开拓新的公共服务增长点以满足不断增长的城乡社会发展需求等建议措施,为确保城乡居民生存发展公平与效率,促进公共服务与城乡互动耦合协调发展提供参考借鉴...     

Sequestration of CO2 in geological media: Criteria and approach for site selection in response to climate change

The well-developed coal electricity generation and coal chemical industries have led to huge carbon dioxide (CO₂) emissions in the northeastern Ordos Basin. The geological storage of CO₂ in saline aquifers is an effective backup way to achieve carbon neutrality. In this case, the potential of saline aquifers for CO₂ storage serves as a critical basis for subsequent geological storage project. This study calculated the technical control capacities of CO₂ of the saline aquifers in the fifth member of the Shiqianfeng Formation (the Qian-5 member) based on the statistical analysis of the logging and the drilling and core data from more than 200 wells in the northeastern Ordos Basin, as well as the sedimentary facies, formation lithology, and saline aquifer development patterns of the Qian-5 member. The results show that (1) the reservoirs of saline aquifers in the Qian-5 member, which comprise distributary channel sand bodies of deltaic plains, feature low porosities and permeabilities; (2) The study area hosts three NNE-directed saline aquifer zones, where saline aquifers generally have a single-layer thickness of 3‒8 m and a cumulative thickness of 8‒24 m; (3) The saline aquifers of the Qian-5 member have a total technical control capacity of CO₂ of 119.25 × 10⁶ t. With the largest scale and the highest technical control capacity (accounting for 61% of the total technical control capacity), the Jinjie-Yulin saline aquifer zone is an important prospect area for the geological storage of CO₂ in the saline aquifers of the Qian-5 member in the study area.     

Characterization of Regional Combustion Efficiency using ΔXCO: ΔXCO2 Observed by a Portable Fourier-Transform Spectrometer at an Urban Site in Beijing

Measurements of column-averaged dry-air mole fractions of carbon dioxide and carbon monoxide, CO₂ (XCO₂) and CO (XCO), were performed throughout 2019 at an urban site in Beijing using a compact Fourier Transform Spectrometer (FTS) EM27/SUN. This data set is used to assess the characteristics of combustion-related CO₂ emissions of urban Beijing by analyzing the correlated daily anomalies of XCO and XCO₂ (e.g., ΔXCO and ΔXCO₂). The EM27/SUN measurements were calibrated to a 125HR-FTS at the Xianghe station by an extra EM27/SUN instrument transferred between two sites. The ratio of ΔXCO over ΔXCO₂ (ΔXCO:ΔXCO₂) is used to estimate the combustion efficiency in the Beijing region. A high correlation coefficient (0.86) between ΔXCO and ΔXCO₂ is observed. The CO:CO₂ emission ratio estimated from inventories is higher than the observed ΔXCO:ΔXCO₂ (10.46 ± 0.11 ppb ppm^?1) by 42.54%–101.15%, indicating an underestimation in combustion efficiency in the inventories. Daily ΔXCO:ΔXCO₂ are influenced by transportation governed by weather conditions, except for days in summer when the correlation is low due to the terrestrial biotic activity. By convolving the column footprint [ppm (μmol m^–2 s^–1)^–1] generated by the Weather Research and Forecasting-X-Stochastic Time-Inverted Lagrangian Transport models (WRF-X-STILT) with two fossil-fuel emission inventories (the Multi-resolution Emission Inventory for China (MEIC) and the Peking University (PKU) inventory), the observed enhancements of CO₂ and CO were used to evaluate the regional emissions. The CO₂ emissions appear to be underestimated by 11% and 49% for the MEIC and PKU inventories, respectively, while CO emissions were overestimated by MEIC (30%) and PKU (35%) in the Beijing area.