Robust Visual Tracking Revisited: From Correlation Filter to Template Matching

In this paper, we propose a novel matching based tracker by investigating the relationship between template matching and the recent popular correlation filter based trackers (CFTs). Compared to the correlation operation in CFTs, a sophisticated similarity metric termed "mutual buddies similarity" (MBS) is proposed to exploit the relationship of multiple reciprocal nearest neighbors for target matching. By doing so, our tracker obtains powerful discriminative ability on distinguishing target and background as demonstrated by both empirical and theoretical analyses. Besides, instead of utilizing single template with the improper updating scheme in CFTs, we design a novel online template updating strategy named "memory filtering" (MF), which aims to select a certain amount of representative and reliable tracking results in history to construct the current stable and expressive template set. This scheme is beneficial for the proposed tracker to comprehensively "understand" the target appearance variations, "recall" some stable results. Both qualitative and quantitative evaluations on two benchmarks suggest that the proposed tracking method performs favorably against some recently developed CFTs and other competitive trackers.Comment: has been published on IEEE TI

Flashlight Search Medial Axis: A Pixel-Free Pore-Network Extraction Algorithm

Pore-network models (PNMs) have become an important tool in the study of fluid flow in porous media over the last few decades, and the accuracy of their results highly depends on the extraction of pore networks. Traditional methods of pore-network extraction are based on pixels and require images with high quality. Here, a pixel-free method called the flashlight search medial axis (FSMA) algorithm is proposed for pore-network extraction in a continuous space. The search domain in a two-dimensional space is a line, whereas a surface domain is searched in a three-dimensional scenario. Thus, the FSMA algorithm follows the dimensionality reduction idea; the medial axis can be identified using only a few points instead of calculating every point in the void space. In this way, computational complexity of this method is greatly reduced compared to that of traditional pixel-based extraction methods, thus enabling large-scale pore-network extraction. Based on cases featuring two- and three-dimensional porous media, the FSMA algorithm performs well regardless of the topological structure of the pore network or the positions of the pore and throat centers. This algorithm can also be used to examine both closed- and open-boundary cases. Finally, the FSMA algorithm can search dead-end pores, which is of great significance in the study of multiphase flow in porous media

Technology transition from traditional oil and gas reservoir simulation to the next generation energy development

Energy transition has been a focus in both scientific research and social concerns in the past decade, thanks to the urgent need of reducing carbon emissions, slowing down the abnormal speed of global climate and achieving a balance between environmental protection and economic development. Although the global energy sector is shifting from the fossil-based energy systems, including oil and gas, to the renewable energy resources like hydrogen, the necessity of conventional energy development has received increasing attentions with regard to the stable supply and maturely developed technologies. The long-history simulation techniques developed for oil and gas reservoir investigations have enabled the deeper explorations into reservoir properties and enhanced significantly the resource recovery. As a main direction in energy transition, the development of hydrogen energy is profoundly influencing the long-term reconstruction of the world’s energy supply and application system, and is accelerating the transition and generational evolution in the fields of transportation, power generation, chemicals, and housing. In this paper, three research directions are proposed as the potential focus of technology transition, where traditional oil and gas reservoir simulation technologies can be adjusted and improved to be used to benefit the development of hydrogen energy.Cited as: Zhang, T., Liu, J., Sun, S. Technology transition from traditional oil and gas reservoir simulation to the next generation energy development. Advances in Geo-Energy Research, 2023, 7(1): 69-70. https://doi.org/10.46690/ager.2023.01.0

Stability analysis of the water bridge in organic shale nanopores: A molecular dynamic study

In the last decades, shale gas development has relieved the global energy crisis and slowed global warming problems. The water bridge plays an important role in the process of shale gas diffusion, but the stability of the water bridge in the shale nanochannel has not been revealed. In this work, the molecular dynamics method is applied to study the interaction between shale gas and water bridge, and the stability can be tested accordingly. CO2 can diffuse into the liquid H2O phase, but CH4 only diffuses at the boundary of the H2O phase. Due to the polarity of H2O molecules, the water bridge presents the wetting condition according to model snapshots and one-dimensional analyses, but the main body of the water bridge in the two-dimensional contour shows the non-wetting condition, which is reasonable. Due to the effect of the molecular polarity, CO2 prefers to diffuse into kerogen matrixes and the bulk phase of water bridge. In the bulk of the water bridge, where the interaction is weaker, CO2 has a lower energy state, implies that it has a good solubility in the liquid H2O phase. Higher temperature does not facilitate the diffusion of CO2 molecules, and higher pressure brings more CO2 molecules and enhances the solubility of CO2 in the H2O phase, in addition, a larger ratio of CO2 increases its content, which does the same effects with higher pressures. The stability of the water bridge is disturbed by diffused CO2 , and its waist is the weakest position by the potential energy distribution.Cited as: Liu, J., Zhang, T., Sun, S. Stability analysis of the water bridge in organic shale nanopores: A molecular dynamic study. Capillarity, 2022, 5(4): 75-82. https://doi.org/10.46690/capi.2022.04.0