Qin Wan^1,2,*, Xiaolin Zhu¹, Yueping Xiao¹, Jine Yan¹, Guoquan Chen¹, Mingui Sun³

CMES-Computer Modeling in Engineering & Sciences, Vol., , DOI:10.32604/cmes.2020.09397

Abstract Detecting moving objects in the stationary background is an important problem in visual surveillance systems. However, the traditional background subtraction method fails when the background is not completely stationary and involves certain dynamic changes. In this paper, according to the basic steps of the background subtraction method, a novel non-parametric moving object detection method is proposed based on an improved ant colony algorithm by using the Markov random field. Concretely, the contributions are as follows: 1) A new nonparametric strategy is utilized to model the background, based on an improved kernel density estimation; this approach uses an adaptive bandwidth, and… More >

Xintao Duan^{1, *}, Daidou Guo¹, Chuan Qin²

CMES-Computer Modeling in Engineering & Sciences, Vol., , DOI:10.32604/cmes.2020.09463

Abstract Image steganography is a technique that hides secret information into the cover image to protect information security. The current image steganography is mainly to embed a smaller secret image in an area such as a texture of a larger-sized cover image, which will cause the size of the secret image to be much smaller than the cover image. Therefore, the problem of small steganographic capacity needs to be solved urgently. This paper proposes a steganography framework that combines image compression. In this framework, the Vector Quantized Variational AutoEncoder (VQ-VAE) is used to achieve the compression of the secret image. The… More >

Qian Yin^1,2, Xiaojing Li^3,*, Liyuan Yu¹, Ming He¹, Richeng Liu^1,2

CMES-Computer Modeling in Engineering & Sciences, Vol., , DOI:10.32604/cmes.2020.08204

Abstract An experimental and numerical study was carried out to investigate the solute removal process through a large-scale fracture plane considering different flow paths and hydraulic head differences. The visualization techniques were utilized in the experiment to capture the removal process images, which were then transferred to binary images. The variations in dimensionless concentration, which is defined as saturation of solute phase, were analyzed. With increasing hydraulic head difference, the speed of solute removal increases and the dimensionless concentration decreases. The flow paths result in different solute distribution patterns and different mechanisms for solute removal such as advection and diffusion, thus… More >

Hongtao Wang^1,2,*, Ping Liu^1,2, Lige Wang^3,4,*, Chi Liu⁵, Xin Zhang^1,2, Luyao Liu^1,2

CMES-Computer Modeling in Engineering & Sciences, Vol., , DOI:10.32604/cmes.2020.08270

Abstract Layered rock strata are observed to be common during the excavation of tunnels or cavities, and may significantly affect the deformation and failure characteristics of surrounding rock masses due to various complex forms and mechanical properties. In this paper, we propose a three-dimensional axisymmetric velocity field for roof collapse of shallow cavities in multi rock layers, by considering the influences of roof cross-section shapes, supporting pressure, ground overload, etc. The internal energy dissipation rate and work rates of external forces corresponding to the velocity field are computed by employing the Hoek-Brown strength criterion and its associated flow rule. Further, the… More >

Xinshuai Shi¹, Hongwen Jing^{1, *}, Jianguo Ning², Zhenlong Zhao¹, Junfu Zhu¹

CMES-Computer Modeling in Engineering & Sciences, Vol., , DOI:10.32604/cmes.2020.07955

Abstract The stability control of gob-side entry retaining in fully mechanized caving face is a typical challenge in many coal mines in China. The rotation and subsidence of the lateral cantilever play a critical role in a coal mine, possibly leading to instability in a coal seam wall or a gob-side wall due to its excessive rotation subsidence. Hence, the presplitting blasting measures in the roof was implemented to cut down the lower main roof and convert it to caved immediate roof strata, which can significantly reduce the rotation space for the lateral cantilever and effectively control its rotation. Firstly, the… More >

Tao Li¹, Qingsheng Yang^{1, *}, Lianhua Ma², Xiaojun Zhang^{2, *}

CMES-Computer Modeling in Engineering & Sciences, Vol., , DOI:10.32604/cmes.2020.09152

Abstract Phase transition of hydrogel, which is polymerized by polymer network, can be regarded as the transition of polymer network stability. The stability of the polymer network might be changed when the external environment changed. This change will lead to the transformation of sensitive hydrogels stability, thus phase transition of hydrogel take place. Here, we present a new free density energy function, which considers the non-gaussianity of the polymer network, chains entanglement and functionality of junctions through adding Gent hyplastic model and Edwards-Vilgis slip-link model to Flory-Huggins theory. A program to calculate the phase transition temperature was written based on new… More >

An Chen^{1, *}

CMES-Computer Modeling in Engineering & Sciences, Vol., , DOI:10.32604/cmes.2020.09224

Abstract In this paper, two classes of Riesz space fractional partial differential equations including space-fractional and space-time-fractional ones are considered. These two models can be regarded as the generalization of the classical wave equation in two space dimensions. Combining with the Crank-Nicolson method in temporal direction, efficient alternating direction implicit Galerkin finite element methods for solving these two fractional models are developed, respectively. The corresponding stability and convergence analysis of the numerical methods are discussed. Numerical results are provided to verify the theoretical analysis. More >

Rashmi Gupta¹, Manju Khari¹, Vipul Gupta¹, Elena Verdú², Xing Wu³, Enrique Herrera-Viedma⁴, Rubén González Crespo^2,*

CMES-Computer Modeling in Engineering & Sciences, Vol., , DOI:10.32604/cmes.2020.010092

Abstract The images capture in a bad environment usually loses its fidelity and contrast. As the light rays travel towards its destination they get scattered several times due to the tiny particles of fog and pollutants in the environment, therefore the energy gets lost due to multiple scattering till it arrives its destination, and this degrades the images. So the images taken in bad weather appear in bad quality. Therefore, single image haze removal is quite a bit tough task. Significant research has been done in the haze removal algorithm but in all the techniques, the coefficient of scattering is taken… More >

Xiaofeng Yang^{1, *}, Yanhong Li¹, Aiguo Nie¹, Sheng Zhi², Liyuan Liu³

CMES-Computer Modeling in Engineering & Sciences, Vol., , DOI:10.32604/cmes.2020.08538

Abstract Supercritical carbon dioxide (Sc-CO₂) jet rock breaking is a nonlinear impact dynamics problem involving many factors. Considering the complexity of the physical properties of the Sc-CO₂ jet and the mesh distortion problem in dealing with large deformation problems using the finite element method, the smoothed particle hydrodynamics (SPH) method is used to simulate and analyze the rock breaking process by Sc-CO₂ jet based on the derivation of the jet velocity-density evolution mathematical model. The results indicate that there exisits an optimal rock breaking temperature by Sc-CO₂. The volume and length of the rock fracture increase with the rising of the… More >

Roberto Bellas^{1, *}, Javier Martínez¹, Ignacio Rivera², Ramón Touza², Miguel Gómez¹, Rafael Carreño¹

CMES-Computer Modeling in Engineering & Sciences, Vol., , DOI:10.32604/cmes.2020.07530

Abstract The study of emergency evacuation in public spaces, buildings and large ships may present parallel characteristic in terms of complexity of the layout but there are also significant differences that can hindering passengers to reach muster stations or the lifeboats. There are many hazards on a ship that can cause an emergency evacuation, the most severe result in loss of lives. Providing safe and effective evacuation of passengers from ships in an emergency situation becomes critical. Recently, computer simulation has become an indispensable technology in various fields, among them, the evacuation models that recently evolved incorporating human behavioral factors. In… More >