压裂改造复合页岩气藏不稳定压力与产量分析方法

为了给页岩气现场开发提供理论依据,考虑页岩气扩散、黏性流、解吸等多种传质机理,建立了复合页岩气藏的综合流动数学模型。基质中考虑浓度差引起的非稳态流动,内外区裂缝中考虑达西流动,水力压裂主裂缝考虑为无限导流;引入了新的无因次量,在椭圆坐标系下综合运用拉氏变换、Mathieu函数、Stehfest数值反演等方法对数学模型进行了解析求解;分析了定产量条件下不稳定压力和定井底压力条件下产量的变化特征,基于不稳定压力曲线将页岩气流动划分为7个流动阶段,即井筒储集阶段、过渡流阶段、早期线性流阶段、基质向裂缝窜流阶段、早期径向流动阶段、第一径向流与第二径向流的过渡阶段、第二径向流动阶段,为复合页岩气藏生产动态分析提供了理论基础。研究结果表明:增大改造区域半径和渗透率可以提高页岩气产量;扩散系数越大、兰格缪尔体积和兰格缪尔压力越大,页岩气产量越大,气藏初始压力高对页岩气的开发具有积极的影响。结论认为,所建立的综合流动数学模型丰富了页岩气多级压裂水平井开发分析方法。     

State and unknown input estimation of an anaerobic digestion reactor with experimental validation

This paper investigates state and unknown input estimations in an Anaerobic Digestion Reactor (ADR) considering a simple two-stage reaction model describing acidogenesis and methanogenesis. From the sole methane outlet flow, this model allows to predict the inlet and outlet biodegradable suspended solid and volatile fatty acid concentrations, which are critical for process stability, as well as acidogenic and methanogenic biomasses. Continuous–discrete exogenous and unknown input formulations of the Extended Kalman Filter (EKF) are applied in this context and a numerical robustness analysis is achieved to characterize sensitivities to measurement noise and model uncertainties. The resulting observers are then validated experimentally with data from a lab-scale plant.     

酸性尾矿废弃地生态修复技术进展

酸性尾矿废弃地废石含有硫化物，在雨水的淋溶作用下会产出硫酸，加剧废弃地的酸化，增加企业环保成本，而生态修复工作就是从源头上控制废弃地的酸化。根据尾矿废弃地酸化机理，结合国内外最新研究进展，分析了生态修复技术现状；概述了隔离覆盖、改良剂改良、植物修复、微生物法等多种处理方法在实践中的适应性及优缺点，并分别介绍了隔离覆盖-植物修复技术、原位改良-植物修复技术在Reden煤矿、永平铜矿的成功应用案例。针对酸性尾矿废弃地的特点，单一处理方法具有较大的局限性，需要采用联合工艺进行治理，隔离覆盖-植物修复技术、原位改良-植物修复技术因见效快、效果好、操作简单，势必成为将来研究的主要方向。     

Progress of Air Pollution Control in China and Its Challenges and Opportunities in the Ecological Civilization Era

China’s past economic growth has substantially relied on fossil fuels, causing serious air pollution issues. Decoupling economic growth and pollution has become the focus in developing ecological civilization in China. We have analyzed the three-decade progress of air pollution controls in China, highlighting a strategic transformation from emission control toward air quality management. Emission control of sulfur dioxide (SO₂) resolved the deteriorating acid rain issue in China in 2007. Since 2013, control actions on multiple precursors and sectors have targeted the reduction of the concentration of fine particulate matter (PM_2.5), marking a transition to an air-quality-oriented strategy. Increasing ozone (O₃) pollution further requires O₃ and PM_2.5 integrated control strategies with an emphasis on their complex photochemical interactions. Fundamental improvement of air quality in China, as a key indicator for the success of ecological civilization construction, demands the deep de-carbonization of China’s energy system as well as more synergistic pathways to address air pollution and global climate change simultaneously.     

问题意识与理性思辨的结晶--评刘文良《绿色与安全:生态包装设计论》

《绿色与安全:生态包装设计论》是当前少有的专门研究生态包装设计的学术专著。该著对于生态包装的概念、生态包装设计的困惑与对策、食品药品等重要民生品包装设计的安全策略、方法与技术等重要理论与实践问题进行了深入探讨,尤其在科学界定生态包装的内涵、理性思辨关于生态包装的某些不合理"常识"以及与时俱进的学术与实践视野方面取得了重要建树。其鲜明的问题意识、务实的研究思路、严谨的求真精神在这部学术专著中得到了印证,为生态包装设计指明了方向、提供了遵循,堪称一把打开生态包装设计大门的"金钥匙"。     

Prophages domesticated by bacteria promote the adaptability of bacterial cells

Prophages are temperate phages integrated into the host bacterial genome. They play an important role in the adaptation and the pathogenicity of bacteria, especially pathogenic bacteria. In this review, we described the distribution of prophages in different hosts and different environments, and focused on the significance of prophages. At the singlecell level, prophages can help the host adapt to harsh external environments by directly carrying virulence genes, encoding regulatory factors and activating lysogeny. At the population level, prophages can influence the overall evolutionary direction and ecological function of the host bacterial community. This review will help us understand the important role of prophages as unique organisms in individual bacteria and microbial populations.     

Analysis of an EMST-based path for 3D meshes

For several 3D data applications such as data-hiding or compression, data ordering is a major problem. We need to know how to achieve the same 3D mesh path between the coding and decoding stages. Various algorithms have been proposed in recent years, but we focus on methods based on Euclidean Minimum Spanning Trees (EMST). In this paper, we analyse the sensitivity of the EMST structure to obtain a more robust synchronization. We present a new theoretical analysis and a way to visualize EMST robustness. Moreover, this analysis can be useful in 3D data-hiding in order to detect fragile area and to predict the 3D object robustness during transmission on a noisy channel.     

Automatic generation control of a multi-area system using ant lion optimizer algorithm based PID plus second order derivative controller

This article presents the automatic generation control of an unequal three area thermal system. Single stage reheat turbines and generation rate constraints of 3%/min are considered in each control area. Controllers such as Integral (I), Proportional – Integral (PI), Proportional – Integral – Derivative (PID), and Proportional – Integral – Derivative Plus Second Order Derivative (PID + DD) are treated as secondary controllers separately. A nature inspired optimization technique called Ant Lion Optimizer (ALO) algorithm is used for simultaneous optimization of the controller gains. Comparison of dynamic responses of frequencies and tie line powers corresponding to ALO optimized I, PI, PID and PID + DD controller reveal the better performance of PID + DD controller in terms of lesser settling time, peak overshoots as well as reduced oscillations. Robustness of the optimum gains of best controller obtained at nominal conditions is evaluated using sensitivity analysis. Analysis exposed that the optimum PID + DD controller gains obtained at nominal are robust and not necessary to reset again for changes in loading, parameter like inertia constant (H), size and position of disturbance. Furthermore, the performance of PID + DD controller is found better as compared to PID controller against random loading pattern condition.     

FSAUA: A framework for sensitivity analysis and uncertainty assessment in historical and forecasted land use maps

Land change modelers often create future maps using reference land use map. However, future land use maps may mislead decision-makers, who are often unaware of the sensitivity and the uncertainty in land use maps due to error in data. Since most metrics that communicate uncertainty require using reference land use data to calculate accuracy, the assessment of uncertainty becomes challenging when no reference land use map for future is available. This study aims to develop a new conceptual framework for sensitivity analysis and uncertainty assessment (FSAUA) which compares multiple maps under various data error scenarios. FSAUA performs sensitivity analyses in land use maps using a reference map and assess uncertainty in predicted maps. FSAUA was applied using three well-known land change models (ANN, CART and MARS) in Delhi, India. FSAUA was found to be a practical tool for communicating the uncertainty with end-users who develop reliable planning decisions.     

A new approach to visualizing time-varying sensitivity indices for environmental model diagnostics across evaluation time-scales

Assessing the time-varying sensitivity of environmental models has become a common approach to understand both the value of different data periods for estimating specific parameters, and as part of a diagnostic analysis of the model structure itself (i.e. whether dominant processes are emerging in the model at the right times and over the appropriate time periods). It is not straightforward to visualize these results though, given that the window size over which the time-varying sensitivity is best integrated generally varies for different parameters. In this short communication we present a new approach to visualizing such time-varying sensitivity across time scales of integration. As a case study, we estimate first order sensitivity indices with the FAST (Fourier Amplitude Sensitivity Test) method for a typical conceptual rainfall–runoff model. The resulting plots can guide data selection for model calibration, support diagnostic model evaluation and help to define the timing and length of spot gauging campaigns in places where long-term calibration data are not yet available.