Rate Dependent Gradient Theory for Shear Band Analysis in Clayey Soils

2001 ◽  
Author(s):  
George Z. Voyiadjis ◽  
Chung R. Song
Keyword(s):  
Flow Characteristics ◽  
Gradient Theory ◽  
Clayey Soils ◽  
Local Behavior ◽  
Local Approach ◽  
Multi Scale ◽  
Viscosity Effect ◽  
Gradient Effect ◽  
Rate Dependent ◽  
Non Local

Abstract A rate dependent, non local approach is developed in this work for geo-materials. A multi-scale gradient theory is addressed for non local approach. Visco-plasticity is also incorporated for an additional regularization of the local behavior. The plastic spin is incorporated to separate the effect of micro-structural rotation from the gradient effect. The flow characteristics of the soil is also incorporated in order to separate the viscosity effect from the flow effect.

Multi-scale non-local approach for geomaterials

2002 ◽  
Vol 29 (2-3) ◽  
pp. 121-129 ◽  
Author(s):  
George Z. Voyiadjis ◽  
Chung R. Song
Keyword(s):  
Local Approach ◽  
Multi Scale ◽  
Non Local

scholarly journals Non-Local and Multi-Scale Mechanisms for Image Inpainting

Sensors ◽  
2021 ◽  
Vol 21 (9) ◽  
pp. 3281
Author(s):  
Xu He ◽  
Yong Yin
Keyword(s):  
Markov Random Fields ◽  
Receptive Fields ◽  
Image Inpainting ◽  
Long Distance ◽  
Visual Appearance ◽  
Fine Grained ◽  
Multi Scale ◽  
Non Local ◽  
Relationship Of

Recently, deep learning-based techniques have shown great power in image inpainting especially dealing with squared holes. However, they fail to generate plausible results inside the missing regions for irregular and large holes as there is a lack of understanding between missing regions and existing counterparts. To overcome this limitation, we combine two non-local mechanisms including a contextual attention module (CAM) and an implicit diversified Markov random fields (ID-MRF) loss with a multi-scale architecture which uses several dense fusion blocks (DFB) based on the dense combination of dilated convolution to guide the generative network to restore discontinuous and continuous large masked areas. To prevent color discrepancies and grid-like artifacts, we apply the ID-MRF loss to improve the visual appearance by comparing similarities of long-distance feature patches. To further capture the long-term relationship of different regions in large missing regions, we introduce the CAM. Although CAM has the ability to create plausible results via reconstructing refined features, it depends on initial predicted results. Hence, we employ the DFB to obtain larger and more effective receptive fields, which benefits to predict more precise and fine-grained information for CAM. Extensive experiments on two widely-used datasets demonstrate that our proposed framework significantly outperforms the state-of-the-art approaches both in quantity and quality.

Local and non-local damage model with extended stress decomposition for concrete

2021 ◽  
pp. 105678952199872
Author(s):  
Bilal Ahmed ◽  
George Z Voyiadjis ◽  
Taehyo Park
Keyword(s):  
Shear Stress ◽  
Degrees Of Freedom ◽  
Biaxial Loading ◽  
Damage Model ◽  
Local Model ◽  
Uniaxial Tensile ◽  
Gradient Theory ◽  
Principal Stresses ◽  
Stress Decomposition ◽  
Non Local

In this work, a new damage model for concrete is proposed with an extension of the stress decomposition (limited to biaxial cases), to capture shear damage due to the opposite signed principal stresses. To extract the pure shear stress, the assumption is made that one component of the shear stress is a minimum absolute of the two principal stresses. The opposite signed principal stresses are decomposed into shear stress and uniaxial tensile/compressive stress. A local model is implemented in Abaqus UMAT and it is further extended to a non-local model by utilization of the gradient theory. The concept of three length scales (tension, compression, and shear) is kept the same as the recently proposed nonlocal damage model by the authors. The nonlocal model is implemented in the Abaqus UEL-UMAT subroutine with an eight-node quadrilateral user-defined element, having five degrees of freedom at corner nodes (displacement in X/Y direction and tensile/compressive and shear nonlocal equivalent strain) and two degrees of freedom at internal nodes. Some examples of a local model including uniaxial and biaxial loading are addressed. Also, five examples of mixed crack mode and mode-I cracking are presented to comprehensively show the performance of this model.

scholarly journals Single image super resolution based on multi-scale structure and non-local smoothing

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Wenyi Wang ◽  
Jun Hu ◽  
Xiaohong Liu ◽  
Jiying Zhao ◽  
Jianwen Chen
Keyword(s):  
Super Resolution ◽  
Principal Component ◽  
Feature Mapping ◽  
Multi Scale ◽  
Non Local ◽  
Image Super Resolution ◽  
Gaussian Blur ◽  
Single Image Super Resolution ◽  
Global And Local ◽  
Bicubic Interpolation

AbstractIn this paper, we propose a hybrid super-resolution method by combining global and local dictionary training in the sparse domain. In order to present and differentiate the feature mapping in different scales, a global dictionary set is trained in multiple structure scales, and a non-linear function is used to choose the appropriate dictionary to initially reconstruct the HR image. In addition, we introduce the Gaussian blur to the LR images to eliminate a widely used but inappropriate assumption that the low resolution (LR) images are generated by bicubic interpolation from high-resolution (HR) images. In order to deal with Gaussian blur, a local dictionary is generated and iteratively updated by K-means principal component analysis (K-PCA) and gradient decent (GD) to model the blur effect during the down-sampling. Compared with the state-of-the-art SR algorithms, the experimental results reveal that the proposed method can produce sharper boundaries and suppress undesired artifacts with the present of Gaussian blur. It implies that our method could be more effect in real applications and that the HR-LR mapping relation is more complicated than bicubic interpolation.

Gradient of Soil Constitutive Model

2010 ◽  
Vol 168-170 ◽  
pp. 1126-1129
Author(s):  
Wen Xu Ma ◽  
Ying Guang Fang
Keyword(s):  
Plastic Strain ◽  
Strain Gradient ◽  
Soil Analysis ◽  
Natural Material ◽  
Flow Rule ◽  
The Finite Element Method ◽  
Gradient Effect ◽  
Non Local ◽  
Associated Flow Rule ◽  
Plastic Strain Gradient

For the soil is a very complex natural material, significant strain gradient effect exist in soil analysis. Based on the "gradient" phenomenon, we add the plastic strain gradient hardening item into the traditional Cambridge yield surface. By using the consistency conditions and associated flow rule, we get the explicit expression of plastic strain gradient stiffness matrix. And the finite element method of plastic strain gradient is also shown in this article. Plastic strain gradient is actually a phenomenological non-local model containing microstructure information of the material. It may overcome the difficulties in simulating the gradient phenomenon by traditional mechanical model.

Multi-scale non-local denoising method in neuroimaging

2016 ◽  
Vol 24 (3) ◽  
pp. 477-487
Author(s):  
Yiping Chen ◽  
Cheng Wang ◽  
Liansheng Wang
Keyword(s):  
Denoising Method ◽  
Multi Scale ◽  
Non Local

scholarly journals Multi-scale laboratory evaluation of the physical, mechanical, and microstructural properties of soft highway subgrade soil stabilized with calcium carbide residue

2016 ◽  
Vol 53 (3) ◽  
pp. 373-383 ◽  
Author(s):  
Ning-Jun Jiang ◽  
Yan-Jun Du ◽  
Song-Yu Liu ◽  
Ming-Li Wei ◽  
Suksun Horpibulsuk ◽  
...  
Keyword(s):  
Particle Size ◽  
Size Distribution ◽  
Calcium Carbide ◽  
Clayey Soils ◽  
Microstructural Properties ◽  
Curing Time ◽  
Multi Scale ◽  
Calcium Carbide Residue ◽  
Mechanical And Microstructural Properties ◽  
Highway Embankment

Calcium carbide residue (CCR) is an industrial by-product, stockpiles of which are rapidly accumulating worldwide. Highway embankment construction has been identified as an avenue to consume huge quantities of CCR as an economical, less energy intensive, and environmentally friendly chemical additive for soil stabilization. Previous studies have investigated the mechanical behavior of soils stabilized by CCR or blends of CCR with other additives; however, interpretation of the macroscale geomechanical behavior of CCR-stabilized soft soils from a systematically microstructural observation and analysis is relatively unknown. This paper presents a multi-scale laboratory investigation on the physical, mechanical, and microstructural properties of CCR-stabilized clayey soils with comparison to quicklime-stabilized soils. Several series of tests were conducted to examine the Atterberg limits, particle-size distribution, compaction characteristics, unconfined compressive strength, California Bearing Ratio, and resilient modulus of the CCR-stabilized clayey soils. The influences of binder content, curing time, and initial compaction state on the physical and mechanical properties of treated soils are interpreted with the aids of physicochemical and microstructural observations including soil pH, soil mineralogy obtained from X-ray diffraction and thermogravimetric analysis, and pore-size distribution obtained from mercury intrusion porosimetry. Soil particle flocculation and agglomeration at the early stage and pozzolanic reactions during the entire curing time, which originate from the finer particle size, greater specific surface area, and higher pH value of CCR, are the controlling mechanisms for the superior mechanical performance of CCR-stabilized soils. The outcomes of this research will contribute to the usage of CCR as a sustainable and alternative stabilizer to quicklime in highway embankment applications.

Characteristic dimensionless numbers in multi-scale and rate-dependent processes

2003 ◽  
Vol 1 (1) ◽  
pp. 7-12 ◽  
Author(s):  
Yilong Bai ◽  
Mengfen Xia ◽  
Haiying Wang ◽  
Fujiu Ke
Keyword(s):  
Dimensionless Numbers ◽  
Multi Scale ◽  
Rate Dependent ◽  
Dependent Processes

Bifurcation and chaos of axially moving nanobeams considering two scale effects based on non-local strain gradient theory

2021 ◽  
pp. 2140010
Author(s):  
Jing Wang ◽  
Huoming Shen ◽  
Bo Zhang ◽  
Jianqiang Sun ◽  
Yuanyuan Zhang
Keyword(s):  
Strain Gradient ◽  
Scale Effects ◽  
Period Doubling ◽  
Local Strain ◽  
Strain Gradient Theory ◽  
Discrete Equation ◽  
Gradient Theory ◽  
Scale Parameters ◽  
Non Local ◽  
Axially Moving

The nonlinear vibration of axially moving nanobeams at the microscale exhibits remarkable scale effects. A model of an axially moving nanobeam is established based on non-local strain gradient theory and considering two scale effects. The discrete equation of a non-autonomous planar system is obtained using the Galerkin method. The response characteristics of the system are determined using phase diagrams and Poincaré sections, and the effects of the scale parameters on the form of the motion are analyzed. The results show that as the non-local parameter and the material characteristic length parameter vary, the system undergoes multiple forms of motion, including periodic, period-doubling and chaotic motions. Two routes to chaos — period-doubling bifurcation and intermittent chaos — are identified in the variation ranges of the two scale parameters.

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