Reduced-order optimal control of water flooding using proper orthogonal decomposition

Model-based optimal control of water flooding generally involves multiple reservoir simulations, which makes it into a time-consuming process. Furthermore, if the optimization is combined with inversion, i.e., with updating of the reservoir model using production data, some form of regularization is required to cope with the ill-posedness of the inversion problem. A potential way to address these issues is through the use of proper orthogonal decomposition (POD), also known as principal component analysis, Karhunen–Loève decomposition or the method of empirical orthogonal functions. POD is a model reduction technique to generate low-order models using ‘snapshots’ from a forward simulation with the original high-order model. In this work, we addressed the scope to speed up optimization of water-flooding a heterogeneous reservoir with multiple injectors and producers. We used an adjoint-based optimal control methodology that requires multiple passes of forward simulation of the reservoir model and backward simulation of an adjoint system of equations. We developed a nested approach in which POD was first used to reduce the state space dimensions of both the forward model and the adjoint system. After obtaining an optimized injection and production strategy using the reduced-order system, we verified the results using the original, high-order model. If necessary, we repeated the optimization cycle using new reduced-order systems based on snapshots from the verification run. We tested the methodology on a reservoir model with 4050 states (2025 pressures, 2025 saturations) and an adjoint model of 4050 states (Lagrange multipliers). We obtained reduced-order models with 20–100 states only, which produced almost identical optimized flooding strategies as compared to those obtained using the high-order models. The maximum achieved reduction in computing time was 35%.     

地面沉降危险性分级标准初探

地面沉降是我国广大平原区最主要的地质灾害。各评估单位对其都有详细的研究和论述,但对危险性程度的划分,尚无统一标准。以沉降速率或累计沉降量划分均不全面,难以给建设单位和规划部门提供一个系统的量化的指标。现应用层次分析法和正交试验法对地面沉降危险性程度进行量化分级,拟对地质灾害评估提供统一的分级标准。     

Combined wavelet and principal component analysis (WEof) of a scale-oriented model of coastal ocean gravity waves

Coastal ocean numerical modeling is basically the representation of the dynamics of the coastal ocean in a chosen range of length scales and over an associated frequency band, including the modeling of both coherent processes and associated transient processes. The ocean dynamical features can be individually identified by combining wavelet analysis for time and frequency localization and principal component analysis to “decorrelate” physically consistent structures. In the present paper, the so-called WEof analysis is applied for the extraction of external gravity waves and internal gravity wave lower modes in a simple case of a flat bottom, constant Brunt-Väisälä ocean. It is shown that, with some well known restrictive assumptions, WEof analysis is an efficient candidate for the recognition of frequency localized dynamical processes.     

水泥土添加剂室内配比试验的模糊正交分析

利用模糊正交试验,对水泥土添加剂室内配比试验结果进行分析。以无侧限抗压强度和试样成本为考核指标,得出水泥土试样在2 8d和90d时水泥掺入比、添加剂掺入比和水灰比的最佳组合,为实际工程提供有价值的参考。     

江淮梅雨期最低气温的气候特征分析

利用江淮地区70个测站1961~2001年历年6月第2侯至7月第2侯最低气温资料,采用旋转经验正交展开(REOF)方法对江淮地区梅雨期最低气温场进行客观分区,并分析了各区域最低气温的长期演变趋势。结果表明:江淮地区梅雨期最低气温场可分为3个区域,各区域的最低气温均具有明显的年际、年代际变化特征,且存在着显著差异,其中东北区明显上升,而南方区和西北区呈降低趋势;各区域存在明显不同的年际、年代际方差构成、突变特征和多尺度振荡周期。     

正交试验在塑料配方中的应用

用正交试验方法对聚硫橡胶改性环氧树脂粘接性能的配方进行了设计试验。正交试验(9次比常规试验(27次)少试验18次,得出同样结果。并对塑料配方技术作初步探讨。     

南亚夏季风期间500hPa环流和系统的变化

应用１９８５年５～９月南亚地区ＯＬＲ格点资料和同期该范围５００ｈＰａ位势高度格点资料，通过自然正交函数（ＥＯＦ）展开和功率谱、交叉谱分析，研究了南亚地区夏季风期间对流发展空间分布的两种主要类型及其和天气系统活动的关系、时间演变特征等。     

正交变换的信息特征分析与选择的研究

对测绘模式识别理论进行研究，特别是对信息特征选择的理论与方法进行分析，在最小均方误差（MSE）准则下，建立了信息特征选择的优化理论模型，并给出解算结果，从而指出了卡南－洛伊夫变换（KLT）是信息特征选择的最优正交变换。根据信息论中熵函数的思想，建立一种新的熵函数－第二表示熵，用它分析KLT下的信息特征及KLT后特征值的信息载荷，从而当给出误差限后，提出信息特征优化选择的一种算法。最后给出在测绘模式识别中的应用模型及算例。