scholarly journals Diffusion Model of Parallel Plate Crack Grouting Based on Foaming Expansion Characteristics of Polymer Slurry

Mathematics ◽  
2021 ◽  
Vol 9 (22) ◽  
pp. 2907
Author(s):  
Jiasen Liang ◽  
Shaokun Ma ◽  
Xueming Du
Keyword(s):  
Diffusion Model ◽  
Crack Width ◽  
Fractured Rock ◽  
Diffusion Mechanism ◽  
Polymer Diffusion ◽  
Grouting Material ◽  
Diffusion Characteristics ◽  
Finite Element Numerical Simulation ◽  
Polymer Slurry ◽  
Good Agreement

Polymers as a new chemical grouting material have been widely used in fractured rock mass; however, the understanding of polymer diffusion characteristics still needs to be further improved. In order to study the diffusion mechanism of foamed polymer slurry in rock fissures, the radial diffusion model of polymer single crack grouting is derived in consideration of the factors such as grouting volume, crack width and expansion rate. The influence of different factors on slurry diffusion radius, diffusion pressure and flow rate is analyzed, The diffusion model is verified by finite element numerical simulation. The findings show that (1) The results of slurry diffusion radius, pressure and velocity distribution at different times under different working conditions in the present model are in good agreement with the analytical solution; (2) The diffusion pressure is directly proportional to the grouting volume and expansion multiple, and inversely proportional to the crack width. In addition, diffusion pressure decreases with the increase of diffusion distance, and the pressure at the corresponding distance increases slowly with time, and finally tends to be stable; (3) For the same section, the radial velocity decreases slowly with the increase of time; for different sections, the flow velocity increases sharply with the increase of the distance between the section and the central axis of the grouting hole.

Growth Kinetics of Fe Boride Layers: Application of a Diffusion Model

2008 ◽  
Vol 273-276 ◽  
pp. 318-322 ◽  
Author(s):  
Mourad Keddam
Keyword(s):  
Diffusion Model ◽  
Growth Kinetics ◽  
Thermodynamic Data ◽  
Boron Content ◽  
Kinetic Constant ◽  
Phase Interface ◽  
Layer Thickness Ratio ◽  
Kinetics Of ◽  
Good Agreement ◽  
Kinetics And Thermodynamic

In the present work, a kinetic study based on a diffusion model was performed by use of both kinetics and thermodynamic data as input parameters, it was possible to evaluate the kinetic constant at each phase interface for a biphase configuration FeB and Fe2B grown over the surfaces of Armco Fe and Fe-Cr binary alloys at 0.5 and 4wt. %Cr by powder- pack boriding. The simulated values of the kinetics constants by the model were compared to those found in the literature and a good agreement was observed. For the Fe-4wt. %Cr alloy, it was found by simulation that the layer thickness ratio between the FeB and Fe2B phases is very sensitive to the increase of temperature and surface boron content.

Pyrolysis behaviors dominated by the reaction–diffusion mechanism in the fluorine-free metal–organic decomposition process

2020 ◽  
Vol 8 (48) ◽  
pp. 17417-17428
Author(s):  
Jiangtao Shi ◽  
Yue Zhao ◽  
Yue Wu ◽  
Jingyuan Chu ◽  
Xiao Tang ◽  
...  
Keyword(s):  
Diffusion Model ◽  
Diffusion Mechanism ◽  
Reaction Diffusion ◽  
Decomposition Process ◽  
One Dimensional ◽  
Reaction Diffusion Model ◽  
Metal Organic ◽  
Free Metal ◽  
Organic Decomposition

In this work, pyrolysis behaviors dominated by the reaction–diffusion mechanism were investigated. And one-dimensional reaction–diffusion model is proposed.

scholarly journals Wound-induced Ca2+ wave propagates through a simple release and diffusion mechanism

2017 ◽  
Vol 28 (11) ◽  
pp. 1457-1466 ◽  
Author(s):  
L. Naomi Handly ◽  
Roy Wollman
Keyword(s):  
Diffusion Model ◽  
Tissue Damage ◽  
Atp Hydrolysis ◽  
Inflammatory Responses ◽  
Diffusion Mechanism ◽  
Fast Activation ◽  
Molecular Patterns ◽  
Damage Associated Molecular Patterns ◽  
And Diffusion ◽  
Source And Sink

Damage-associated molecular patterns (DAMPs) are critical mediators of information concerning tissue damage from damaged cells to neighboring healthy cells. ATP acts as an effective DAMP when released into extracellular space from damaged cells. Extracellular ATP receptors monitor tissue damage and activate a Ca2+ wave in the surrounding healthy cells. How the Ca2+ wave propagates through cells after a wound is unclear. Ca2+ wave activation can occur extracellularly via external receptors or intracellularly through GAP junctions. Three potential mechanisms to propagate the Ca2+ wave are source and sink, amplifying wave, and release and diffusion. Both source and sink and amplifying wave regulate ATP levels using hydrolysis or secretion, respectively, whereas release and diffusion relies on dilution. Here we systematically test these hypotheses using a microfluidics assay to mechanically wound an epithelial monolayer in combination with direct manipulation of ATP hydrolysis and release. We show that a release and diffusion model sufficiently explains Ca2+-wave propagation after an epithelial wound. A release and diffusion model combines the benefits of fast activation at short length scales with a self-limiting response to prevent unnecessary inflammatory responses harmful to the organism.

Simulation of the Early Startup Period of High-Temperature Heat Pipes From the Frozen State by a Rarefied Vapor Self-Diffusion Model

1993 ◽  
Vol 115 (1) ◽  
pp. 239-246 ◽  
Author(s):  
Y. Cao ◽  
A. Faghri
Keyword(s):  
Heat Pipe ◽  
Diffusion Model ◽  
Numerical Results ◽  
Vapor Flow ◽  
Pipe Length ◽  
Self Diffusion ◽  
Temperature Heat ◽  
Startup Process ◽  
Startup Period ◽  
Good Agreement

The heat pipe startup process is described physically and is divided into five periods for convenience of analysis. The literature survey revealed that none of the previous attempts to simulate the heat pipe startup process numerically were successful, since the rarefied vapor flow in the heat pipe was not considered. Therefore, a rarefied vapor self-diffusion model is proposed, and the early startup periods, in which the rarefied vapor flow is dominant within the heat pipe, are first simulated numerically. The numerical results show that large vapor density gradients existed along the heat pipe length, and the vapor flow reaches supersonic velocities when the density is extremely low. The numerical results are compared with the experimental data of the early startup period with good agreement.

scholarly journals Diffusion Mechanism Modeling of Metformin in Human Organic Cationic Amino Acid Transporter one and Functional Impact of S189L, R206C, and G401S Mutation

2021 ◽  
Vol 11 ◽  
Author(s):  
Leydy Cano ◽  
Alejandro Soto-Ospina ◽  
Pedronel Araque ◽  
Maria Antonieta Caro-Gomez ◽  
Maria Victoria Parra-Marin ◽  
...  
Keyword(s):  
Type 2 Diabetes ◽  
Amino Acids ◽  
Electronic Structure ◽  
Diffusion Model ◽  
Structural Model ◽  
Diffusion Mechanism ◽  
Electron Cloud ◽  
Coupling Energy ◽  
The Impact

Metformin used as a first-line drug to treat Type 2 Diabetes Mellitus is transported via organic cation channels to soft tissues. Mutations in the SLC22A1 gene, such as Gly401Ser, Ser189Leu, and Arg206Cys, may affect the drug’s therapeutic effect on these patients. This study aims at proposing a potential structural model for drug interactions with the hOCT1 transporter, as well as the impact of these mutations at both topological and electronic structure levels on the channel’s surface, from a chemical point of view with, in addition to exploring the frequency distribution. To chemically understand metformin diffusion, we used an open model from the protein model database, with ID PM0080367, viewed through UCSF Chimera. The effect of the mutations was assessed using computational hybrid Quantum Mechanics/Molecular Mechanics, based on the Austin Model 1 semi-empirical method using Spartan 18’ software. The results demonstrate coupling energy for metformin with amino acids F, W, H and Y, because of the interaction between the metformin dication and the electron cloud of π orbitals. The mutations analyzed showed changes in the chemical polarity and topology of the structure. The proposed diffusion model is a possible approach to the interaction mechanism between metformin and its transporter, as well as the impacts of variants, suggesting structural changes in the action of the drug. Metformin efficacy considerably varies from one patient to another; this may be largely attributed to the presence of mutations on the SLC22A1 gene. This study aims at proposing a potential structural model for metformin-hOCT1 (SLC22A1) transporter interaction, as well as the identification of the effect of mutations G401S (rs34130495), S189L (rs34104736), and R206C (616C > T) of the SLC22A1 gene at the topological and electronic structure levels on the channel surfaces, from a chemical viewpoint. Our results demonstrated that the coupling energies for metformin with aromatic amino acids F, W, H and Y, because of the interaction between the metformin dication and the electron cloud of π orbitals. Changes in the chemical environment’s polarity and the structure’s topology were reported in the mutations assessed. The diffusion model proposed is a potential approach for the mechanism of interaction of metformin with its transporter and the effects of variants on the efficacy of the drug in the treatment of type 2 diabetes. The assessment of the frequency of these mutations in a sample of Colombian type 2 diabetes patients suggests that different SLC22A1 gene variants might be involved in reduced OCT1 activity in the Colombian population since none of these mutations were detected.

scholarly journals Grouting Mechanism in Water-Bearing Fractured Rock Based on Two-Phase Flow

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-18
Author(s):  
Bo Ren ◽  
Wenqiang Mu ◽  
Bingyou Jiang ◽  
Guofeng Yu ◽  
Lianchong Li ◽  
...  
Keyword(s):  
Diffusion Model ◽  
Flow Model ◽  
Two Phase Flow ◽  
Fractured Rock ◽  
Optimization Method ◽  
Phase Flow ◽  
Optimization Scheme ◽  
Two Phase ◽  
Height Range ◽  
Basic Work

Grouting is always used in mine water plugging, reinforcement, and other disaster prevention projects. The diffusion mechanism of slurry in fractured rock is affected by geological environment and slurry performance, which should be revealed and characterized better. Based on the two-phase flow diffusion theory, a slurry diffusion model considering flowing water condition was established for a blocking area of a fracture zone in one case from China. The feasibility of two-phase flow model in grouting diffusion calculation was analyzed. The diffusion model in dynamic water environment was studied, and the diffusion range varying with time in the grouting area of Zhangji Coal Mine was explored. The optimization method of multi grouting holes was put forward, and the influence of water flowing was discussed. The results show that the slurry diffusion calculated by the two-phase flow model was feasible and consistent with the experimental study. The dynamic water can change the conventional circular diffusion state of slurry, but its pattern was oval and leaf type. There were different penetration distances in directions, and typical grouting voids were made on the side and upstream. When the single-hole grouting was carried out, the predetermined value can be achieved in the height range, but it was only about 15 m on the side because of the water flowing, which cannot meet the requirements. The optimization scheme of grouting was put forward, which adopted multiple grouting holes in the long side, and grouting in different directions and periods to avoid the possible problems of multihole intersection. The rationality and effectiveness of the proposed optimization method were verified through the calculation of water yield and analysis of cement composition from the drilling core in the grouted zone. In the grouting process, the water flowing has double effects, which has a significant role in promoting and scouring along the flow direction, but there is a significant weakness in the side diffusion. It is very important to realize the rational use of the dynamic water through the optimization scheme. This study is an important basic work of grouting mechanism, and it is expected to promote the development of grouting technology and application of two-phase fluid-solid coupling theory.

A Resource Recommendation Method Based on User Taste Diffusion Model in Folksonomies

2012 ◽  
Vol 3 (1) ◽  
pp. 18-30 ◽  
Author(s):  
Jiangning Wu ◽  
Yunfei Shi ◽  
Chonghui Guo
Keyword(s):  
Diffusion Model ◽  
Diffusion Mechanism ◽  
Personalized Recommendation ◽  
Collaborative Tagging ◽  
Relation Model ◽  
Sparsity Problem ◽  
The Given ◽  
And Diffusion ◽  
Tagging System ◽  
The Web

Collaborative tagging has been very popular with the development of the Web 2.0, which helps users manage, share and utilize resources effectively. For various kinds of resources, the way to recommend appropriate resources to right users is the key problem in tagging system. This paper proposes a user taste diffusion model based on the tripartite hypergraph to deal with the tri-relation of user-resource-tag in folksonomies and the data sparsity problem in personalized recommendation. Through the defined tri-relation model and diffusion probability matrix, the user’s taste is diffused from itself to other users, resources and tags. When diffusion stops, the candidate resources can be identified then be ranked according to the taste values. As a result the top resources that have not been collected by the given user are selected as the final recommendations. Benefiting from the introduction of iterative diffusion mechanism, the recommendation results not only cover the resources collected by the given user’s direct neighbors but also cover the ones which are collected by his/her extended neighbors. Experimental results show that our method performs better in terms of precision and recall than other recommendation methods.

Non-Destructive Electrical Techniques as Means for Understanding the Basic Mechanisms of Electromigration

1994 ◽  
Vol 337 ◽  
Author(s):  
A. Scorzoni ◽  
I. De Munari ◽  
H. Stulens
Keyword(s):  
Experimental Data ◽  
High Resolution ◽  
Mechanical Stress ◽  
Diffusion Model ◽  
Physical Mechanism ◽  
Relative Resistance ◽  
Resistance Change ◽  
Non Destructive ◽  
Theoretical Results ◽  
Good Agreement

ABSTRACTIn this paper results of recently developed high resolution resistometric electromigration techniques will be described, with particular attention to the behaviour of narrow, near-bamboo metal lines. After a discussion on recent theoretical results published in the literature, a diffusion model correlating mechanical stress and electromigration will be adopted to describe experimental results of relative resistance change both during and after electromigration. The good agreement between experimental data and simulations must not hide that something must still be understood about the physical mechanism leading to resistance changes during electromigration experiments.

Drying Behavior of Polyester Based Yarn Bobbins in a Hot-Air Bobbin Dryer

2011 ◽  
Vol 312-315 ◽  
pp. 848-853
Author(s):  
Ahmet Cihan ◽  
Kamil Kahveci ◽  
Ugur Akyol ◽  
Dinçer Akal
Keyword(s):  
Mass Transfer ◽  
Diffusion Coefficient ◽  
Textile Industry ◽  
Diffusion Mechanism ◽  
Moisture Ratio ◽  
Transfer Model ◽  
Hot Air ◽  
Air Temperatures ◽  
Drying Behavior ◽  
Good Agreement

Drying behavior of polyester based yarn bobbins (67% polyester, 33% viscose) was simulated for different drying air temperatures by a simultaneous heat and mass transfer model. In the model, it was assumed that mass transfer is occurred by the diffusion mechanism. In the study, firstly drying behavior of polyester bobbins for different drying air temperatures has been determined experimentally. The experiments were conducted on an experimental hot-air bobbin dryer designed and manufactured based on hot-air bobbin dryers used in textile industry. In the experimental setup, temperatures of different points of the bobbins were measured by thermocouples placed inside the bobbins and weight of the bobbins during the drying period were determined by a load cell. Then moisture ratio and temperature values of the model have been fitted to the experimental ones. The fit was performed by selecting the values for the diffusion coefficient and the thermal diffusivity in the model in such a way that these values make the sum of the squared differences between the experimental and the model results for moisture ratio and temperature minimum. The results show that there is a good agreement between the model results and the experimental ones. The results also show that temperature has a significant effect on mass transfer and temperature dependence of the diffusion coefficient may be explained by an Arrhenius type relation.

Measurement of the Impurity Diffusivity of Cu in Fe by Laser Induced Breakdown Spectrometry

2005 ◽  
Vol 237-240 ◽  
pp. 266-270 ◽  
Author(s):  
Chan Gyu Lee ◽  
Jung Han Lee ◽  
Byeong Seon Lee ◽  
Yong Ill Lee ◽  
Toshitada Shimozaki ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Diffusion Coefficients ◽  
Boundary Diffusion ◽  
Volume Diffusion ◽  
Diffusion Mechanism ◽  
Grain Boundary Diffusion ◽  
Impurity Diffusion ◽  
Boundary Diffusion Coefficient ◽  
Laser Induced Breakdown ◽  
Good Agreement

The impurity diffusion coefficients of Cu in Fe have been determined in the temperature range of 1073 - 1163 K by means of Laser Induced Breakdown Spectrometry (LIBS). The volume diffusion coefficients for Cu impurity diffusion in a-iron found in this work are in good agreement with the previously published result. The grain boundary diffusion coefficient gb D s d was also calculated using the volume diffusivity and processing the tails of the measured profiles. The values of the activation energy for volume and grain boundary diffusion were approximately 280 and 161 kJmol-1, respectively. This indicates the possibility of a monovacancy diffusion mechanism in case of volume diffusion. The results for the diffusion coefficients are Dv= 2.2 ×10-2exp(-280 kJmol-1/RT) m2s-1 and gb D s d = 2.6 ×10-11exp(-161 kJmol-1/RT) m3s-1.

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