An approach to extracting surface supply relationships between glaciers and lakes on the Tibetan Plateau

Surface supply relationships between glaciers and lakes are needed to analyze and understand hydrological processes at regional and global scales. However, these supply relationships still cannot be extracted efficiently by existing methods. This paper proposes an automatic and efficient approach to extracting surface supply relationships between glaciers and lakes based on meltwater flow paths. The approach includes two stages: (1) identifying direct connections between objects (i.e. glaciers and lakes) based on flow direction derived from digital terrain analysis on a gridded digital elevation model (DEM) and (2) deriving all (or user-specified) kinds of surface supply relationships based on graph search. All computation-intensive steps in this approach have been parallelized; and all steps in the proposed approach have been integrated as an automatic program. Results for the Tibetan Plateau show that given outline data for glaciers and lakes and the Shuttle Radar Topography Mission DEM, the proposed approach can automatically derive diverse surface supply relationships under user-specified restrictions on the attributes of the supply route. The parallelization in the approach effectively improves the computing efficiency. The proposed approach could also be applied to developing a detailed fundamental dataset of supply relationships between glaciers and lakes for other region or period.     

An analytical model for multiple fractured shale gas wells considering fracture networks and dynamic gas properties

Multi-stage fractured horizontal wells play an important role in developing shale gas reservoirs by significantly improving productivity. By considering fracture networks, gas desorption, stress-sensitive fracture permeability, and pressure-dependent gas PVT properties, an analytical model is developed for shale gas wells. Fracture networks are handled based on transient linear flow, gas desorption is handled by defining a new total compressibility, stress-dependent hydraulic fracture permeability is handled by variable substitution, and pseudo-pressure and pseudo-time are used to handle pressure-dependent PVT properties. After obtaining the solution of the linearized model, a material balance method and successive substitution iteration procedure are proposed to convert the pseudo-time into real time and calculate the production contribution from gas desorption. The results show that induced fractures also have a great impact on the production of the well. Production contribution from free gas and adsorbed gas could be quantified using the proposed material balance principle and iterative method. The rank of parameters that influence the ultimate recovery is the following: half-length of hydraulic fracture, induced fracture length/hydraulic fracture spacing, hydraulic fracture spacing, conductivity of induced fractures, conductivity of hydraulic fracture, and induced fracture spacing.     

Real-time fusion of multiple videos and 3D real scenes based on optimal viewpoint selection

3D real scenes are a digital virtual space that represents and portrays the real world in a photorealistic, three-dimensional, and sequential manner. Existing methods for constructing and updating 3D models, such as oblique photography and laser scanning, are difficult to meet the demand of perceiving the real world intuitively, dynamically, and in real time. In recent years, the method of integrating rapidly rising video data and 3D models has become increasingly popular. Compared with existing methods, it enhances the real-time perception of 3D scenes by taking advantage of the real-time character of videos and the intuitive character of 3D models. In this article, we propose a real-time fusion method of multiple videos and 3D real scenes based on optimal viewpoint selection. To begin, 3D reconstruction and video camera calibration were used to prepare the basic data for the fusion of videos and 3D model. Second, a visible-surface detection-based video space restoration method was provided, and the overlapping region between multiple videos was determined. Third, to split the overlapping region into the corresponding camera spaces, a segmentation method based on optimal viewpoint selection was given. Finally, the 2D videos were dynamically fitted to the 3D model using the dynamic texture mapping method, while accomplishing the fusing and rendering of the 3D real scene. After experimental verification, the overall effect of the multiple videos and 3D real scene fusion system implemented using the method proposed in this article is better, while the algorithm is less time-consuming and efficient in rendering.     

Integrating domain knowledge and graph convolutional neural networks to support river network selection

Deep learning is increasingly being used to improve the intelligence of map generalization. Vector-based map generalization, utilizing deep learning, is an important avenue for research. However, there are three questions: (1) transforming vector data into a deep learning data paradigm; (2) overcoming the limitation of the number of samples; and (3) determining whether existing knowledge can accelerate deep learning. To address these questions, taking river network selection as an example, this study presents a framework integrating hydrological knowledge into graph convolutional neural networks (GCNNs). This framework consists of the following steps: constructing a dual graph of river networks (DG_RN), extracting domain knowledge as node attributes of DG_RN, developing an architecture of GCNNs for the selection, and designing a fine-tuning rule to refine the GCNN results. Experiments show that our framework outperforms existing machine learning and traditional feature sorting methods using different datasets and achieves good morphological consistency after the selection. Furthermore, these results indicate that DG_RN meets the data paradigm of graph deep learning, and the framework integrating existing characteristics (i.e., Strahler coding, the number of tributaries, the distance between proximity rivers, and upstream drainage area) mitigates the dependence of GCNNs on plenty of samples and enhance its performance.     

鄂尔多斯盆地镇泾油田致密砂岩长8储层特征及沉积相研究

利用扫描电镜、铸体薄片等多种方法,对鄂尔多斯盆地镇泾油田长8油层组低孔低渗的致密砂岩储层的储层特征和沉积相进行综合分析研究,发现该地区砂岩类型主要有细粒岩屑长石砂岩和长石岩屑砂岩,孔隙度和渗透率分别为3.9%%~11%和(0.04~0.55)×10-3μm2。研究区主要成岩作用包括压实作用、压溶作用、胶结作用、溶蚀作用、交代作用。通过对镇泾区块沉积储层形成的沉积相的研究,查明该区广泛发育三角洲相,进一步可划分为水下分流河道、水下天然堤、水下决口扇、水下分流间湾、河口坝等5种微相。上述研究为镇径油田长8段储层的研究和预测提供了理论依据。     

Analytical layer element solutions for deformations of transversely isotropic multilayered elastic media under nonaxisymmetric loading

This paper presents the analytical layer element solutions for deformations of transversely isotropic elastic media subjected to nonaxisymmetric loading at an arbitrary depth. The state vectors for the nonaxisymmetric problem are deduced through the substitution of the Hu Hai‐chang solutions into the basic equations for the transversely isotropic elastic media. From the state vectors, the analytical layer element of a single layer is obtained in the Hankel transformed domain. The analytical layer element is an exact and symmetric stiffness matrix whose elements are without positive exponential functions, which can not only simplify the calculation but also improve the stability of computation. On the basis of the continuity conditions between adjacent layers, the global stiffness matrix is obtained by assembling the interrelated layer elements. The solutions for the multilayered elastic media in the transformed domain are obtained by solving the algebraic equation of the global stiffness matrix, which satisfies the boundary conditions. The actual solutions in the physical domain are further obtained by inverting the Hankel transform. Finally, some cases are analyzed to verify the solutions and evaluate the influences of the transversely isotropic character and stratified character of the media on the load–displacement responses. The numerical results show that the variations of the elastic properties between layers have a great effect on the displacements of the multilayered media. Copyright © 2014 John Wiley & Sons, Ltd.     

Removal of bisphenol A from aqueous solution using cetylpyridinium bromide (CPB)-modified natural zeolites as adsorbents

Surfactant-modified natural zeolites (SMNZs) with different coverage types were prepared by loading cetylpyridinium bromide onto the surface of natural zeolites. The resulting SMNZs were characterized and used as adsorbents to remove bisphenol A (BPA) from aqueous solution. The monolayer and bilayer SMNZs were effective for removing BPA from aqueous solution. The BPA adsorption capacity for the monolayer SMNZ increased slightly with increasing pH from 4 to 9, but decreased significantly with increasing pH from 9 to 11. The BPA adsorption capacity for the bilayer SMNZ was relatively high at pH 9–10, but decreased with decreasing pH from 9 to 4 or increasing pH from 10 to 11. The equilibrium adsorption data of BPA on the monolayer and bilayer SMNZs under the experimental condition could be well described by the Langmuir and Freundlich isotherm models. The adsorption kinetics of BPA on the monolayer and bilayer SMNZs followed a pseudo-second-order model. The adsorption of BPA on the monolayer and bilayer SMNZs took place in three different stages: a fast external surface adsorption, a gradual adsorption controlled by both the external mass transfer and the intra-particle diffusion, and a final equilibrium stage. The adsorption of BPA on the monolayer and bilayer SMNZs is spontaneous and exothermic. The mechanisms for BPA adsorption onto the monolayer SMNZ at pH 4–11 include the hydrophobic interaction and hydrogen bonding. The mechanisms for BPA adsorption onto the bilayer SMNZ at pH 4–8 include the organic partitioning and hydrogen bonding. The mechanisms for BPA adsorption onto the bilayer SMNZ at pH 8–11 include the organic partitioning, hydrogen bonding and electrostatic attraction.     

干法灰化和微波消解-电感耦合等离子体发射光谱法测定植物样品中22个主次量元素

采用干法灰化和微波消解两种样品分解方法处理植物试样,用电感耦合等离子体发射光谱法测定样品中铝、钡、钙、铜、钾、镁、钠、铁等22个主、次量元素的含量,用两种前处理方法对国家一级标准物质进行测定,比对测定值与标准值,验证两种方法的准确度和精密度。结果表明,不同的样品分解方法对各元素的测定结果会产生不同程度的影响。选择适宜的分解方法可以大大提高植物样品中铝、铁、硫等元素测定结果的准确度。干法灰化和微波消解两种前处理方法的精密度(RSD,n=11)均小于5%。     

粘弹介质本构理论讨论

阐述了建立物质本构关系时应满足的基本公理,较详细地推导了各种类型粘弹性物质的本构关系,论述了变率理论与泛函数论之间的关系,推导了对于粘弹性问题求解具有实用意义的对应定理,并以简单的例子说明对应定理的应用。