Semi-log Scale Research Articles

Two-phase flow pattern identification in CAES systems with dimensional analysis coupled with support vector machine

Two-phase bubbly flow can lead to challenges during the charging period for hydraulically-compensated Compressed Air Energy Storage systems. In this study, upward two-phase flow systems have been investigated in large diameter vertical pipes to better understand when the transitions to problematic flow regimes occur. A comprehensive dimensional analysis was conducted, considering vertical pipe geometry and fluid thermophysical properties. Nine dimensionless parameters and three two-phase flow maps were created. The plot of liquid Reynolds number, ReL, over the Two-phase Reynolds number, Retp,made classification between the Bubbly, Slug, and Churn flow difficult for large diameter pipes. The plot of the two-phase Capillary number,Catp, over the liquid Reynolds number, ReL, showed large overlap of the data sets extracted from the literature. This may have been due to the weakness of the capillary number in defining the larger pipe flow behaviours. The last flow map based on the Slippage number, Sltp, versus the two-phase Froude number, Frtp, showed an exponential decay relationship between the Froude and Slippage parameter. When this was converted to the semi-log scale it provided a valuable classification map of two-phase flow. Finally, a Support Vector Machine (SVM) technique applied to the 2D plot of (Sltp- Frtp), gave a useful transition boundary to separate regimes in air-water upward flows in large diameter pipes.

Generalized expression for the self-normalized signal in photothermal experiments for multilayered materials in the frequency domain

The analytical solution for diffusion of heat for a four-layered material, in a surface absorption model, is used to describe a simple diagram-based construction methodology for obtaining the analytical solution for a general photothermal signal in the transmission and front photothermal configurations. The general expressions derived can be used for analysis during the application of self-normalized photothermal experimental techniques to thermal diffusivity measurements in the frequency domain. The thermally thick limit of these equations can be used to obtain an effective thermal diffusivity expression for multilayered systems that can be used to retrieve the thermal diffusivities of buried layers. If such a system consists of alternating layers of two different materials, as is the case for some heterostructures and superlattices, it is possible to obtain the thermal impedances at the interfaces of the consecutive layers. Although the resulting self-normalized expressions are complex, their thermally thick limit reduces them to linear equations for the photothermal phase and amplitude (amplitude in semi-log scale). This simplifies the analysis required to obtain quantitative results.

Pharmacokinetics Study of the Long-acting Antiarrhythmic Drug of Lappaconitine Hydrobromide (Allaforte®, JSC "Pharmcenter VILAR", Russia)

Introduction.Allaforte® (JSC "Pharmcenter VILAR", Russia) is an antiarrhythmic long-acting drug. The dosage form of the drug Allaforte® provides a decrease in the frequency of taking the drug and also reduces the risk of side effects. It is relevant when taking antiarrhythmic drugs of the IC class. However, the pharmacokinetics of this drug has not been studied on humans. Therefore, it is important to fully study the pharmacokinetics to ensure the maximum efficacy and safety of arrhythmia therapy.Aim.The aim is pharmacokinetics study of long-acting antiarrhythmic drug Allaforte® (JSC "Pharmcenter VILAR", Russia), 25 mg. Materials and methods. Concentration of lappaconitine and its active metabolite N-desacetyllappaconitine in human plasma determinates by high performance liquid chromatography with tandem mass-spectrometry. Pharmacokinetic parameters calculated by R Project 3.5.1 software (package «bear», version 2.8.3-2), originally created by Hsin-ya Lee and Yung-jin Lee, Taiwan.Results and discussion.Pharmacokinetic parameters of lappaconitine and N-desacetyllappaconitine were calculated. Averaged pharmacokinetic profiles (in linear and semi-log scale) of lappaconitine and N-desacetyllappaconitine after single administration under fasting were built. The means of the maximum concentrations (Cmax) determined in the blood plasma of volunteers after single administration Allaforte® are 5.09 ± 4.07 ng/ml for lappaconitine and 11.66 ± 6.21 ng/ml for N-deacetyllappaconitine (Mean ± SD). The peak time of the maximum concentrations (Tmax) is 4.43 ± 3.54 hours for lappaconitine and 4.04 ± 2.18 hours for N-deacetyllappaconitine. The means of the areas under the curve plasma concentration – time from 0 to 48 hours (AUC0-t) and under the curve plasma concentration–time from zero to infinity (AUC0-∞) of Allaforte® is 42.96 ± 34.48 ng ∙ h/ml and 71.24 ± 43.20 ng ∙ h/ml for lappaconitine; 167.42 ± 114.41 ng ∙ h/ml and 189.42 ± 115.20 ng ∙ h/ml for N-deacetyllappaconitine. Allaforte® was eliminated from blood plasma with means of terminal half-life (T1/2) 8.45 ± 5.10 hours for lappaconitine and 9.04 ± 2.57 hours for N-deacetyllappaconitine.Conclusion.Pharmacokinetics study of long-acting antiarrhythmic drug Allaforte® (JSC "Pharmcenter VILAR", Russia) after single administration was researched. Results of the study allows to conduct an effective therapy of arrhythmia by study drug and minimize side effects.

Rheological Characterization of Fine-Grained Sediments under Steady and Dynamic Conditions

The objective of this study is to investigate the steady and dynamic rheological behavior and characteristics of fine-grained sediments. A series of laboratory tests were conducted using an Anton Paar MCR 102 rheometer to investigate the rheological properties of the fine-grained sediments at various water to solid (W/S) ratios. In the steady-state measurement condition, the results indicate that fine-grained sediments are a non-Newtonian viscous fluid, and the presence of yield stress of fine-grained sediments is evident and is influenced by the W/S ratios. For the determination of yield stress, two types of methods were used: by defining the minimum value of shear stress from flow curves experimental data in semilog scale and by modeling the flow curves following different rheological models. From the results obtained, it appears that the Casson model was the best one to characterize the rheological behavior of fine-grained sediments, because of its high coefficient of determination R2 and the lowest mean absolute percentage error, also close to the measured yield stress value. In the dynamic state measurement condition, the loss modulus (G″) is markedly smaller than the elastic modulus (G′), indicating that fine-grained sediments are predominantly elastic (in the range of amplitude and frequencies explored). The complex viscosity (η*) sharply decreases with the frequency increase, but the frequency dependence of the G′ and G″ is rather weak. The G′, G″, η*, and loss factor (tan δ) significantly reduced with the increase of the W/S ratio. In the end, the dynamic rheological properties of fine-grained sediments can be expressed as appropriate functions of the W/S ratios. This study not only provided a guideline for having a better understanding of the rheology of fine-grained sediments but will also provide scientific support for understanding and solving all kinds of natural and manmade activities involving fine-grained sediments, such as dredged sediments handling and transport by pipelines, landslides caused by rainfall or earthquake; generation and movement of mudflows, laying and maintenance of submarine cables and pipelines, and deep-sea mining engineering.

Effect of radial hydride on room temperature fracture toughness of Zr-2.5Nb pressure tube material

The effect of radial hydride on the room temperature fracture toughness of the Zr-2.5Nb pressure tube material with 100% radial hydrides and hydrogen content up to 320wppm was investigated using curved compact tension (CCT) specimens. The hydride continuity coefficients (HCC) representing hydrogen content and hydride orientation were determined between 0 and 1. It was observed that the role of plastic deformation on the fracture toughness mechanism decreases with increase in HCC. On a semi-log scale the fracture toughness of the Zr-2.5Nb pressure tube varied linearly with HCC at room temperature and this is characteristic feature for the Zirconium alloys.

Ventilatory inefficiency during graded exercise in COPD: A pragmatic approach.

The current approach to measuring ventilatory (in)efficiency (V'E -V'CO2 slope, nadir and intercept) presents critical drawbacks in the evaluation of COPD subjects, owing mainly to mechanical ventilatory constraints. Thus, we aimed to compare the current approach with a new method we have developed for ventilatory efficiency calculation. The new procedure was based on measuring the amount of CO2 cleared by the lungs (V'CO2 , L/min) plotted against a predefined range of increase in minute ventilation (V'E ) (ten-fold increase based on semilog scale) during incremental exercise to symptom-limited maximum tolerance. This value was compared to a hypothetical predicted maximum CO2 output at the predicted maximal voluntary ventilation, defining ventilatory efficiency (ηV'E , %). The results were used to compare 30 subjects with COPD (II-IV Global Initiative for Chronic Obstructive Lung Disease, GOLD) and 10 non-COPD smokers, to establish the best discriminative physiological variable for disease severity through logistic multinomial regression. The new approach was more sensitive to progressive deterioration of airway obstruction, resulting in worse ηV'E as lung function worsens throughout the GOLD panel (ηV'E (%), p<.001), when compared with V'E -V'CO2 slope (p=.715) or V'E -V'CO2 nadir (p=.070), besides showing the best model based on the logistic regression approach. Although requiring more complex calculations compared to the current procedure, the new approach is highly sensitive to true ventilatory/gas-exchange deterioration, even throughout more severe pulmonary lung function in COPD subjects.

An interactive web-based dashboard to track COVID-19 in Colombia. Case study: five main cities.

Design and implement an interactive web-based dashboard to track COVID-19 in Colombia. A tool was designed and implemented to analyze the data of Covid-19 positive cases in Colombia and published by the Instituto Nacional de Salud. The tool is based on the implementation of business intelligence methods with which you can understand the behavior of the pandemic in Colombia and generate structured data for decision-making by government levels. The tool displays, on a single screen, information on the number of cases, patient status, age ranges, city, location department, and gender. This information can be dynamically filtered and focus analyzes on the national, departmental, or municipal order. Additionally, methods are implemented for trend analysis, both on a linear and semi-log scale, as well as for calculating the case fatality rate in each of the municipalities. A web-based data analysis dashboard is implemented for semi-continuous monitoring of the COVID-19 pandemic in Colombia. With the use of the tool, a situational analysis is carried out for five of the most important cities in Colombia. The application is effective, flexible, and easy to use. The situational analysis reflects that public policies for the control of the disease have been favorable for Medellín, but for Cartagena, Bogotá, Barranquilla, and Cali, complementary measures are required.

Simplified traction prediction for highly loaded rolling/sliding EHL contacts

A simplified traction prediction approach has been developed for highly loaded EHL contacts accounting for non-Newtonian and thermal effects. For validation, a reference fluid squalane was used for traction measurements at high Hertzian contact pressures (1.25 to 2.66GPa) at three velocities of 5, 10 and 15m/s. Good agreement was seen for traction curves in a semi-log scale at a low speed of 5m/s, whereas for higher speeds at 10m/s and 15m/s, the measured traction curves are lower than the predicted ones. This reduced friction in the experimental results is caused by the increase in mass temperature of the discs. Two possible mechanisms for this reduced friction due to solid body temperature effects are discussed.

Influence of biochar addition on gas permeability in unsaturated soil

Biochar (BC) has been proposed as an alternative soil amendment in landfill cover. Its effects on soil hydraulic properties (e.g. soil water retention) have been explored to some extent, while its influence on landfill gas flow characteristics is not clear yet. The objective of this study is to investigate the water retention and gas permeability (kg) of BC-amended soil and its relationship with soil water content in unsaturated state. In total, three BC contents (0, 5 and 10%) were considered in clay–sand mixtures. Soil suction, water content and gas pressure were measured continuously using a new in-house developed apparatus. Test results show that the presence of BC increased soil water content and the increased amount was almost the same over a wide range of suction values (up to 3 MPa). kgincreased linearly with soil suction in semi-log scale, regardless of the BC content. The addition of 5 and 10% of BC could decrease kgby up to 50 and 65%, respectively, compared with that of the bare soil. kgdecreased with water content for both soil and BC -amended soils. Moreover, the decrease rate of kgwith water content became smaller when the BC percentage was higher.

Analysis of gas production data via an intelligent model: application to natural gas production

Predicting the future oil and gas production rate and evaluating oil/gas reserves are very challenging issues. Many engineers have found decline curve analysis a useful approach (Ahmed, 2010; Arps, 1945; Ebrahimi, 2010; Fetkovich, 1980; Gentry, 1972; Li and Horne, 2005; Ling and He, 2012; Oghena, 2012; Shirman, 1999; Zheng and Fei, 2008). The production rate or cumulative production at a constant bottom-hole pressure declines with time (Ahmed, 2010). Since mechanisms affecting the production are constant throughout the lifetime of a reservoir, extrapolating decline curves is used to forecast the future production rate. To do so, initial production rate, the decline curvature, and its rate should be considered (Ahmed, 2010). Arps’s equations are fundamental for the most heuristic and conventional decline curve analysis models (Arps, 1945). Arps demonstrated that the hyperbolic family of equations can express mathematically the curvature behaviour of the production rate versus time curve. The Arps (Arps, 1945) equations are divided into three categories, including exponential, hyperbolic, and harmonic decline curve models. Fetkovich (Fetkovich, 1980) proposed type curves for analysing decline curves. The procedure of type curve matching is summarized by the visual matching with log-log paper that includes pre-plotted curves of production data. Each of the curves has characteristics which can be shown when plotting them on Cartesian, semi-log and log-log scales as shown in Figure 1.

Comment on “Charge Carrier Extraction in Organic Solar Cells Governed by Steady‐State Mobilities”

Comment on “Charge Carrier Extraction in Organic Solar Cells Governed by Steady‐State Mobilities”

Fatigue characterization of GFRP and composite sandwich panels under random ocean current loadings

A comprehensive fatigue characterization of Glass Fiber Reinforced Plastic (GFRP) and composite sandwich panels under random ocean current loadings is presented in this paper. Two sources of randomness in ocean currents were considered in the calculation of fatigue load: one is turbulence in the ocean currents and the other is the wake flow behind the support structure of the turbine. Calculated random loading was applied to conduct fatigue tests on GFRP and composite sandwich coupons using a materials testing machine. Fatigue life of GFRP coupons followed a power function pattern with respect to number of spectrum passes, while that of sandwich panels was linear in semi-log scale. The failure modes, S-N curve, and the constant life diagram under constant amplitude test are also discussed.

A comparative study of Hankel transform filters for marine controlled-source electromagnetic surveys

Using a closed-form solution of the Hankel transform in transverse magnetic mode for a homogeneous half-space model, we can assess the accuracy of digital linear filters for evaluating the Hankel transform. In this paper, we conduct comparative performance tests on the linear filter with known integral transforms. We examine three kinds of filters developed by W. L. Anderson, F. N. Kong and H. Mizunaga, which are known to be suitable for marine controlled-source electromagnetic (CSEM) applications. Kong’s filters perform best in the three kinds of filters over a practical range of offset distances in marine CSEM surveys. While the relative error versus distance appears as a V-shaped curve in semi-log scale, Mizunaga’s filters are the shortest in length and have a performance comparable to Kong’s filters. Anderson’s filters have a quite similar performance between the J0 and J1 filters, although these are somewhat inferior to Kong’s and Mizunaga’s filters when computing marine CSEM fields.

Laboratory observation of engineering properties and deformation mechanisms of cemented rubber-sand mixtures

This paper presents details of a study that deals with investigation of compression behaviors, stiffness properties, and microstructural characteristics of lightly cemented and uncemented rubber-sand mixtures. The rubber-sand mixtures specimens were prepared with various sand volume fractions to evaluate its effects on the engineering properties. The specimens were subjected to different levels of vertical stress under K0 condition and the shear wave velocity (Vs) was measured simultaneously by bender elements during the compression process. Investigations were carried out with respect to the effect of sand fraction and the level of vertical stress on the overall rubber-sand mixtures properties including stress-strain characteristics, Vs, and small strain shear modulus (G0). In addition, scanning electron microscopy analysis was conducted to understand the variations in microstructure and the deformation mechanisms controlling the changes in engineering properties of the cemented rubber-sand mixtures. The study reveals that sand fraction has a considerable influence on the mass density (ρ), stress-strain characteristics, and stiffness properties of cemented and uncemented mixtures. These changes are attributed to the remarkable difference of engineering properties between shredded rubber and sand particles. The vertical strain presents three behavior regions as a function of stress in semi-log scale for lightly cemented rubber-sand mixtures: bonding control, bonding degradation, and stress control. Residual strain of the specimen decreases with an increase in sand fraction, and its value of cemented specimen is much lower than that of uncemented specimen. The Vs and G0 dramatically increase with an increase in sand fraction and vertical stress. A good linear relationship is proposed between Vs and vertical stress for uncemented rubber-sand mixtures. Additional loading of the vertical stress decreases the increment of Vs as a result of bonding degradation. The response of stress-strain and Vs can be employed as indicators of cementation degradation. Two different deformation mechanisms: rubber particles deformation and the force chains generated by sand particles were proposed for rubber-sand mixtures with different sand fractions. Rubber particles sustain loads and suffer a dramatical shape change when mixtures with a small amount of sand, whereas they play an important role in preventing the buckling of sand particle chains with high sand fraction.

Development of a Novel Automated Screening Method for Detection of FVIII Inhibitors

Background Factor VIII activity is determined by directly measuring the aPTT of a patient plasma sample and determining the percent activity from a standard curve generated from plotting the measured clotting time (in seconds) on a semi-log scale vs a known percent activity of the standard at several specific dilution points. Factor VIII activity for the patient samples is then performed on dilutions of patient plasma mixed with equal amounts of plasma deficient in the factor to be measured, and the percent of factor in the patient plasma is calculated from the standard curve by plotting the observed clotting time for a specific dilution of the patient sample. To minimize the potential for under-reporting an activity level or missing the presence of an inhibitor (defined as an antibody directed against Factor VIII), a subjective assessment of parallelism of the patient curve to the standard curve is performed. In absence of an inhibitor the standard and patient curves are parallel to each other with the patient curve’s slope (Ps) similar to the standard curve’s slope (Cs). In patients with an inhibitor, the clotting time is prolonged. Furthermore, with each subsequent dilution, the amount of inhibitor is diluted out, leading to shorter clotting times for subsequent dilutions. In practice this leads to a less steep patient curve slope (Ps) compared to the standard curve slope (Cs) and thus nonparallel lines.Aim Parallelism determination is currently a subjective assessment that leads to increased error in reporting, potential missed evaluation for inhibitors and potential unnecessary testing for inhibitors. We developed an objective and automated tool to assess parallelism as an added screening tool for the presence of a Factor VIII inhibitor.Methods We performed Factor VIII assays (Low Factor VIII assay modification on STA Compact using low curve calibration at 1:6, 1:15 and 1:30 dilution (STA Deficient VIII, Immuno-Depleted Plasma for Factor VIII:C assay by STA. Package insert 26217-revised September 1994)) at appropriate dilutions on Factor VIII deficient hemophilia patients. We examined curves for parallelism by comparing the ratio of the slope of the curve generated from patient dilutions without detectable inhibitor (disease-free state) and the slope of the curve generated from patient dilutions with a known inhibitor (disease state) vs the slope of the standard curve. We confirmed presence of an inhibitor for each patient sample by Bethesda assay utilizing the Nijmegen modification.Results Using a bell curve generated from a parameter simulation of obtained Ps/Cs ratios from screening 21 samples with and without an inhibitor, we determined a ratio of Ps/Cs of 0.45 to be a cut-off that was 100% sensitive and 80% specific for detection of an inhibitor.To confirm the validity of this cut-off, we screened 48 de-identified samples with and without low FVIII inhibitor (Bethesda titers <5) obtained from the NHLBI biologic specimen and data repository. In this larger sample set, our cut-off ratio of <0.45 for the detection of an inhibitor to FVIII was 100% sensitive and 91.6% specific, with a positive predictive value of 92.3% and a negative predictive value of 100%.Conclusion We developed and validated a new screening tool for detecting the presence of an inhibitor to Factor VIII during routine FVIII assays. This method has the potential to screen for the detection of inhibitors to other specific clotting factors such as FIX, lupus anticoagulants and the presence of the newer oral anticoagulants which directly inhibit Factor Xa or thrombin. DisclosuresNo relevant conflicts of interest to declare.

Macrocrack propagation in concrete specimens under sustained loading: Study of the physical mechanisms

This study presents a series of 4-point bending tests performed to describe the delayed behavior of unreinforced pre-cracked beams under low, moderate and high sustained loading levels. The deflection creep rate, the failure time and the load level were assessed. A linear relation, in a semi-log scale, was found for the deflection creep rate at high load levels. In addition, a linear relation, in a log–log scale, between the secondary deflection creep rate and failure time was observed.Besides, it was shown that the secondary creep deflection rate increases with the sustained loading level and the macrocrack propagation rate when macrocrack propagation occurs during the sustained loading.Physical mechanisms are proposed to explain these results and may be summarized as follows: the delayed behavior of an unreinforced cracked concrete specimen under sustained loading is mainly due to the cracking evolution, thus the creation of microcracks and/or the propagation of a macrocrack.

Correlation of Outcrop Hydraulic Conductivity with its Aquifer: A Case Study of the Phu Phan Sandstone in Northeast, Thailand

Fractured rock aquifers provide the most extensive groundwater resources in Northeast Thailand. The hydraulic conductivity (K) of these aquifers controls the flow of water and is therefore, an essential parameter for groundwater modeling and management. K values may be directly determined by conducting pumping tests at the aquifer or by performing fracture analysis using data acquired from outcrops. The K value at outcrop should be greater than that at aquifer of deeper position due to the effect of aperture reduction by overburden compression. The goal of this study was therefor to find the correlation between K values determined from outcrop with those directly measured at an aquifer. This study was conducted on the Phu Phan sandstone aquifer at the Huay Luang watershed, Udon Thani Province of Northeast Thailand. The orientation, aperture, and spacing of fractures were measured at four outcrops and used for determining the K values by fracture analysis. Single well pump test data from 17 wells in the Phu Phan aquifer (30-120 m depth) were analyzed to obtain transmissivity (T) and K. Both sets of the K values, from outcrop and aquifer, were correlated using the plotting position of Weibull. Both plots were linear on a semi-log scale but the outcrop curve was steeper. Lognormal distributions fitted both plotting positions quite well. These results show that for the same probability value, K values found from the pumping test to be about an order of magnitude smaller than K values determined from outcrop data.

Tensile behavior of concrete under high loading rates

The experimental and theoretical studies show that the influence of loading rate on tensile behavior of concrete is relatively strong. Dynamic tensile resistance of concrete is difficult to measure by direct tensile test. Therefore, the indirect tensile tests such as split Hopkinson bar tests are used. The evaluation of experimental measurements shows that after reaching a certain critical strain rate, tensile resistance progressively increases with increasing strain rate. In this paper, the authors attempt to investigate and discuss: (i) the reason for progressive increase of tensile resistance beyond a certain strain rate and (ii) whether the dynamic resistance can be attributed only to material strength or whether some other factors also contribute towards the same. To answer these questions, numerical analysis on two different types of examples is carried out: (i) Simple elastic-cohesive finite element (FE) model subjected to direct tension and (ii) FE model of indirect tension test on modified split Hopkinson bar. The results are evaluated in terms of apparent and true strength and compared with experimental results. It is found that under static loads, the true and apparent strengths are always equal, while under dynamic loads they are different. The true strength is controlled by the rate dependent constitutive law and the apparent strength is significantly influenced by the size of the fracture process zone and the size of the specimen. Evaluation of numerical results shows that concrete fracture energy is approximately a linear function of strain rate (semi-log scale) and is controlled by the rate dependent constitutive law. It is concluded that the results of any indirect tension test such as split Hopkinson bar test need careful interpretation, i.e. due to the fact that concrete specimen is damaged, and not elastic, the results of measurement need to be corrected.

Settlement-Time Behavior of Steel Piles in Gypsifereous Sand- A Model Prototype Study

There are a lot of studies conducted on gypseous soils dealing with the effect of collapsibility on the general behavior of the soil concerning its strength properties, settlement indexes, volume-mass relationship and permeability. To get rid of the bad soil properties then one goes into another subject as dealing with the aspects of soil improvement or replacement and the like. This study is devoted to settlement investigation of a small prototype pile erected into gypsifereous soil, loaded to 70% of its ultimate bearing load, socked for two hours and then leached with water for seven days. In preparing testing soil, well graded sand is mixed with pure gypsum in ratios of gypsum content of 10, 20, 30, 50, 70%. The loading frame is locally manufactured as to apply loads and to record settlement of pile. The results revealed that when gypsum is less than 10% or 20%, settlement recorded is small. The settlement-time curves show a convetional “S” shape in a semi-log scale. Maximum settlement obtained is for gypsum content of 70% and is about 30% of pile diameter. Finally, three additional socking and leaching tests are also conducted by using 5% concentration of CH3COOH (acid), grade-60 viscosity oil, and kerosene for specimens containing 50% of gypsum. Specimen socked and leached by oil shows very little settlement, while the specimen treated with kerosene shows less settlement as compared with water. The specimen treated with 5% concentration of CH3COOH shows 50% increase in settlement.

점토 함유량에 따른 점토질 모래의 투수 및 압밀 특성 평가

Evaluation of permeability and coefficient of consolidation of clayey sand is critical in analyzing ground stability or environmental problems such as prediction of pollutant transport in groundwater. In this study, permeability tests using a flexible wall permeameter are performed to derive the coefficient of consolidation and permeability of reconstituted soil samples with various mixing ratios of kaolin clays and two different types of sands, which are Jumunjin and Ottawa sands. The test results indicate that the coefficient of consolidation and permeability plots linearly against clay contents in semi-log scale graphs for low clay mixing ratios ranging between 10 to 30%. It is also demonstrated that coefficient of consolidation and permeability of sand and clay mixture are dependent on the soil structure. Contrary to previous findings, the permeability is shown to be independent of the void ratio at low mixing ratios, which can be classified as non-floating fabric. The permeability decreases with the void ratio for floating fabric.