scholarly journals Moisture Transfer and Formation of Separate Ice in the Freezing Process of Saturated Soils

Water ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 1044 ◽  
Author(s):  
Peishuai Chen ◽  
Huiwu Luo ◽  
Enlong Liu
Keyword(s):  
Moisture Transfer ◽  
Freezing Process ◽  
Analysis Method ◽  
Soil Columns ◽  
Physical Mechanisms ◽  
Initial Stage ◽  
Final Layer ◽  
Classical Criterion ◽  
Lens Formation ◽  
New Criterion

The formation and layer of ice lenses during the freezing of soil in cold regions is closely related to frozen heave and moisture immigration. The purpose of the paper is to explain the physical mechanisms pertaining to ice lens formation, which were analyzed and verified using numerical simulation results. Based on a few assumptions, the formation and layers of ice lenses are illuminated in the following steps: the initial stage of freezing, formation of the first layer of ice lens, formation of the second layer of ice lens, and formation of the final layer of ice lens. Compared with the numerical results of coupled thermo–hydro–mechanical simulations of one-side freezing of soil columns in an open system, the proposed analysis method of the formation and layers of ice lenses is verified to be reasonable, and it is demonstrated that the classical criterion for the formation of ice lens in freezing saturated soil is only suitable for the final layer of ice lens. Finally, a new criterion, in terms of flux rate, for the formation of ice lens is proposed.

scholarly journals SOLUTIONS FOR PROMOTING THE DEVELOPMENT OF VALUE ENGINEERING IN THE VIETNAMESE CONSTRUCTION INDUSTRY

2020 ◽  
Vol 30 (06) ◽  
Author(s):  
VIET THANH NGUYEN ◽  
SOO-YONG KIM ◽  
VAN TRUONG LUU
Keyword(s):  
Factor Analysis ◽  
Literature Review ◽  
Construction Industry ◽  
Value Engineering ◽  
Pilot Test ◽  
Correlation Effects ◽  
Analysis Method ◽  
Initial Stage ◽  
The World ◽  
Effective Degree

Nowadays, Value Engineering (VE) is being widely practiced in many countries around the world. However, its concepts and applications do not seem to be well embraced in the Vietnamese construction industry. This study aims to seek solutions for promoting the development of VE in the Vietnamese construction industry. Most of the previous studies gave solutions in deficiencies and lack of analysis. On the basis of literature review and interviews with experts during the pilot test of the study at the initial stage, fifteen solutions were identified. A questionnaire survey was then conducted to rate the effective degree of the fifteen solutions. This study revealed six most effective solutions that should be taken with first priorities to promote the VE development. Additionally, the factor analysis method was applied to investigate the correlation effects of the solutions, which resulted in four core factors representing the solutions, namely, positive interest from government and construction stakeholders; education about VE; presence of VE organizations in the construction industry; and interaction with the outside world. The findings of the study are expected to bring the most effective solutions to promote the development of VE in the Vietnamese construction industry.

scholarly journals A Leap-Frog Finite Difference Method for Strongly Coupled System from Sweat Transport in Porous Textile Media

2019 ◽  
Vol 2019 ◽  
pp. 1-16
Author(s):  
Qian Zhang ◽  
Chao Huang
Keyword(s):  
Finite Difference ◽  
Finite Difference Method ◽  
Difference Method ◽  
Moisture Transfer ◽  
Coupled System ◽  
Optimal Error Estimates ◽  
Strongly Coupled ◽  
Physical Mechanisms ◽  
Uniqueness Of The Solution ◽  
Heat And Moisture

In this paper, we present an uncoupled leap-frog finite difference method for the system of equations arising from sweat transport through porous textile media. Based on physical mechanisms, the sweat transport can be viewed as the multicomponent flow that coupled the heat and moisture transfer, such that the system is nonlinear and strongly coupled. The leap-frog method is proposed to solve this system, with the second order accuracy in both spatial and temporal directions. We prove the existence and uniqueness of the solution to the system with optimal error estimates in the discrete L2 norm. Numerical simulations are presented and analyzed, respectively.

Associated probabilities aggregations in multistage investment decision-making

Kybernetes ◽  
2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Gia Sirbiladze ◽  
Harish Garg ◽  
Irina Khutsishvili ◽  
Bezhan Ghvaberidze ◽  
Bidzina Midodashvili
Keyword(s):  
Decision Making ◽  
Choquet Integral ◽  
Fuzzy Measure ◽  
Investment Model ◽  
Content Type ◽  
Owa Operators ◽  
Second Stage ◽  
Intuitionistic Fuzzy ◽  
Classical Criterion ◽  
New Criterion

PurposeThe attributes that influence the selection of applicants and the relevant crediting decisions are naturally distinguished by interactions and interdependencies. A new method of possibilistic discrimination analysis (MPDA) was developed for the second stage to address this phenomenon. The method generates positive and negative discrimination measures for each alternative applicant in relation to a particular attribute. The obtained discrimination pair reflects the interaction of attributes and represents intuitionistic fuzzy numbers (IFNs). For the aggregation of applicant's discrimination intuitionistic fuzzy assessments (with respect to attributes), new intuitionistic aggregation operators, such as AsP-IFOWA and AsP-IFOWG, are defined and studied. The new operators are certain extensions of the well-known Choquet integral and Yager OWA operators. The extensions, in contrast to the Choquet aggregation, take into account all possible interactions of the attributes by introducing associated probabilities of a fuzzy measure.Design/methodology/approachFor optimal planning of investments distribution and decreasing of credit risks, it is crucial to have selected projects ranked within deeply detailed investment model. To achieve this, a new approach developed in this article involves three stages. The first stage is to reduce a possibly large number of applicants for credit, and here, the method of expertons is used. At the second stage, a model of improved decisions is built, which reduces the risks of decision making. In this model, as it is in multi-attribute decision-making (MADM) + multi-objective decision-making (MODM), expert evaluations are presented in terms of utility, gain, and more. At the third stage, the authors construct the bi-criteria discrete intuitionistic fuzzy optimization problem for making the most profitable investment portfolio with new criterion: 1) Maximization of total ranking index of selected applicants' group and classical criterion and 2) Maximization of total profit of selected applicants' group.FindingsThe example gives the Pareto fronts obtained by both new operators, the Choquet integral and Yager OWA operators also well-known TOPSIS approach, for selecting applicants and awarding credits. For a fuzzy measure, the possibility measure defined on the expert evaluations of attributes is taken.Originality/valueThe comparative analysis identifies the applicants who will receive the funding sequentially based on crediting resources and their requirements. It has become apparent that the use of the new criterion has given more credibility to applicants in making optimal credit decisions in the environment of extended new operators, where the phenomenon of interaction of all attributes was also taken into account.

Study on Surface Roughness of Al2024 Alloy during Shot Peening Process Based on Finite Element Method

2017 ◽  
Vol 748 ◽  
pp. 229-234
Author(s):  
Xuan Zheng ◽  
Dong Wei Gao
Keyword(s):  
Surface Roughness ◽  
Finite Element ◽  
Shot Peening ◽  
Surface Deformation ◽  
Analysis Method ◽  
Alloy Plate ◽  
Initial Stage ◽  
Al2024 Alloy ◽  
Explicit Dynamic ◽  
Metallic Target

Based on the explicit dynamic analysis method, the finite element models of successive shots and multiple shots for shot peening process are established by using LS-DYNA software.The simulations of the elastic-plastic dynamic process of shots impacting on a metallic target during shot peening process were accomplished. For Al2024-T3 alloy plate, the surface roughness induced by shot peening is studied and the effect of overlapping on the general trend is evaluated.The analysis results show that the surface roughness increases rapidly at the initial stage of shot peening and forms micro-scale pits. With the increase of the coverage, the surface deformation increased slowly when the surface coverage reached 100%.

FREEZING PROCESSES IN SATURATED SOILS

1998 ◽  
Vol 08 (01) ◽  
pp. 107-138 ◽  
Author(s):  
F. TALAMUCCI
Keyword(s):  
Porous Matrix ◽  
Freezing Process ◽  
Porous Space ◽  
Migration Process ◽  
Overburden Pressure ◽  
Soil Frost ◽  
One Dimensional ◽  
Frost Penetration ◽  
The One ◽  
Lens Formation

When a soil saturated with water is subject to freezing, a volume expansion can generally be observed. The increase in volume is due not only to the different densities of water and ice, but mainly to a water migration process that is transported from the base of the soil up to an intermediate region where the change of phase occurs. It is generally accepted that a transition region, called frozen fringe, where ice and water coexist in the porous space, separates the unfrozen from the frozen part of the soil. Immediately over the frozen fringe a pure segregated layer of ice (ice lens) can form. If the freezing process is too fast or the weight acting on the soil (overburden pressure) is relevant, the porous matrix does not separate and the shifting of the frozen fringe towards the base of the soil (frost penetration) is observed. Many mathematical models have been proposed for the frost heave process. The main features of the one-dimensional model we are considering are summarized in Sec. 1. In Ref. 9 the case of assignment of the boundary thermal fluxes (at the base and on top of the soil) is studied. In practical cases, sometime the boundary temperatures, instead of the thermal fluxes, can be registered or imposed: in this paper we will investigate the model in such case. The main purpose is to detect which are the boundary values for temperature that determine the process of lens formation or frost penetration, once the properties of the soil are known.

Study on Model of Heat and Moisture Transfer in Freezing Soil

2012 ◽  
Vol 170-173 ◽  
pp. 97-100
Author(s):  
Zhi Qiang Ji ◽  
Xue Yan Xu ◽  
Chuan Kai Zhao
Keyword(s):  
Numerical Model ◽  
Moisture Transfer ◽  
Frozen Soil ◽  
Freezing Process ◽  
Equilibrium Equations ◽  
Freezing Soil ◽  
Mechanical Deformations ◽  
Orthotropic Properties ◽  
Heat And Moisture ◽  
Porosity Changes

The purpose of this paper is to present a numerical model of coupled heat, moisture transfer and their effects on the porosity changes of soil during the freezing process. Coupling among heat, moisture, and mechanical deformations is solved based on finite element method. The equilibrium equations of freezing process are investigated based on segregation theory. The numerical model is applied to a 2D problem of a laboratory frost heave test. Numerical simulation reveals the porosity characters during the freezing process. The frost depths and deformations also the porosity in consideration of the orthotropic properties of frozen soil is discussed.

scholarly journals Quantitative Measuring Analysis Method and Mechanism of Wear Particle Settlement

2021 ◽  
Vol 252 ◽  
pp. 03037
Author(s):  
Kaituo Zhang ◽  
Zhiyong Lv
Keyword(s):  
Specific Gravity ◽  
Magnetic Induction ◽  
Wear Particle ◽  
Lubricating Oil ◽  
Precipitation Process ◽  
Wear Particles ◽  
Analysis Method ◽  
Abrasive Particles ◽  
Initial Stage ◽  
Precipitation Analysis

The size and distribution of wear particle in lubricating oil, as important numerical information available in ferrography, is one of the key indexes in wear diagnosis. In this paper, a new method for measuring the size and distribution of abrasive particles is proposed. First, all the abrasive fluid is left standing until all the abrasive particles are precipitated to the bottom. Then, the measuring container is inverted and the whole precipitation process of abrasive particles is recorded by magnetic induction instrument. And according to the precipitation analysis of the wear particle, the following results were obtained:1) At the initial stage of the particle settlement, the gravity, the buoyancy and the drag force of the oil achieve balance quickly, the time and distance of the wear particle moving at a constant velocity can be neglected. 2) The settling velocity is related to the diameter and specific gravity of the wear particle as well as the specific gravity and viscosity of the oil, the distribution of the wear particle is proportional to the square of the diameter of the particle, using the magnetic induction technology, the distribution of particle can be measured by settling time for different sizes of wear particles. 3) Measure the wear particle oil directly, there are different sizes of particles settlement in the bottom at the same time, which causes the difficulty in identifying the size of the particle settlement. The particle should be settled first, and then inverted, settling the particle in accordance with the order from large to small, which facilitates the measurement of different sizes of the particles, different times correspond to different sizes of the particles. 4) The bigger the particle is, the more accurate the measurement and counting is, the smaller the particle is, the bigger the error is.

Simplified Dynamics Modeling of Seat-Passenger in Vehicle Frontal Crash

2014 ◽  
Vol 597 ◽  
pp. 544-550
Author(s):  
Yao Yuan Wang ◽  
Zhuo Yang Lyu ◽  
Liang Liang Wang ◽  
Zhen Hua Yan
Keyword(s):  
Differential Equation ◽  
Dynamic Model ◽  
Fourth Order ◽  
Dynamics Analysis ◽  
Kutta Method ◽  
Analysis Method ◽  
Dynamics Modeling ◽  
Frontal Crash ◽  
Runge Kutta Method ◽  
Initial Stage

To quickly predict the performance of the seat in frontal crash during the initial stage of the seat development, in this paper a simplified coupled dynamic model of seat-passenger interaction is established according to the dynamics analysis method of Lagrange, and the fourth order Runge-Kutta method is used to resolve differential equation. Moreover, the simulation of Madymo testifies the simplified coupled dynamic model of seat-passenger interaction in frontal crash. Therefore, this model will be effective and feasible in predicting the performance of the seat in frontal crash during the initial stage of the seat development, for example, the performance of anti-submarining protection.

Influence of overconsolidation on the freezing characteristics of a clayey silt

1989 ◽  
Vol 26 (1) ◽  
pp. 9-21 ◽  
Author(s):  
J.-M. Konrad
Keyword(s):  
Hydraulic Conductivity ◽  
Void Ratio ◽  
Moisture Transfer ◽  
Frozen Soil ◽  
Frost Heave ◽  
Unfrozen Water ◽  
Initial Void Ratio ◽  
Clayey Silt ◽  
Segregation Potential ◽  
Lens Formation

Laboratory freezing tests were performed on a saturated clayey silt at various overconsolidation ratios (OCR) to establish the relationship between initial void ratio and stress history, and the amount of moisture transfer during freezing. The frost heave tests were analysed in terms of the segregation potential as well as a function of the temperature of ice lens formation and the overall hydraulic conductivity of the frozen fringe. All other factors being the same, the segregation potential was found to increase with increasing values of OCR (decreasing initial void ratios). However, the combined effects of decreasing void ratio and increasing suction at the frost line, all other factors being identical in all freezing tests, resulted in decreasing segregation potentials. This trend was the result of a decrease in the temperature of ice lens formation and the concomitant decrease in overall hydraulic conductivity of the frozen fringe. A simple model showed that the capillary unfrozen water between clay particles increases when the particles pack closer together, as overconsolidation increases, allowing the migratory water to freeze within the frozen soil at a colder temperature. Key words: frost heave, clayey silt, overconsolidation, void ratio.

scholarly journals A new fractal-theory-based criterion for hydrological model calibration

2021 ◽  
Vol 25 (6) ◽  
pp. 3675-3690
Author(s):  
Zhixu Bai ◽  
Yao Wu ◽  
Di Ma ◽  
Yue-Ping Xu
Keyword(s):  
Model Calibration ◽  
Hydrological Model ◽  
Fractal Theory ◽  
Fractal Dimensions ◽  
Hydrological Models ◽  
Classical Criterion ◽  
Potential Benefits ◽  
New Criterion ◽  
Squared Residuals ◽  
Different Climates

Abstract. Fractality has been found in many areas and has been used to describe the internal features of time series. But is it possible to use fractal theory to improve the performance of hydrological models? This study aims at investigating the potential benefits of applying fractal theory in model calibration. A new criterion named the ratio of fractal dimensions (RD) is defined as the ratio of the fractal dimensions of simulated and observed streamflow series. To combine the advantages of fractal theory with classical criteria based on squared residuals, a multi-objective calibration strategy is designed. The selected classical criterion is the Nash–Sutcliffe efficiency (E). The E–RD strategy is tested in three study cases with different climates and geographies. The results reveal that, in most aspects, introducing RD into model calibration makes the simulation of streamflow components more reasonable. Also, pursuing a better RD during calibration leads to only a small decrease in E. We therefore recommend choosing the parameter set with the best E among the parameter sets with RD values of around 1.

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