scholarly journals Assessment of empirical formulae for determining the hydraulic conductivity of glass beads

2018 ◽  
Vol 66 (3) ◽  
pp. 337-347 ◽  
Author(s):  
Jaromír Říha ◽  
Lubomír Petrula ◽  
Mario Hala ◽  
Zakaraya Alhasan
Keyword(s):  
Experimental Data ◽  
Hydraulic Conductivity ◽  
Glass Bead ◽  
Glass Beads ◽  
Experimental Measurements ◽  
Variable Porosity ◽  
Porosity Function ◽  
Series Of Experiments ◽  
Best Fit

Abstract Empirical formulae are often used in practice to quickly and cheaply determine the hydraulic conductivity of soil. Numerous relations based on dimensional analysis and experimental measurements have been published for the determination of hydraulic conductivity since the end of 19th century. In this paper, 20 available empirical formulae are listed, converted and re-arranged into SI units. Experimental research was carried out concerning hydraulic conductivity for three glass bead size (diameters 0.2 mm, 0.5 mm and 1.0 mm) and variable porosity. The series of experiments consisted of 177 separate tests conducted in order to obtain relevant statistical sets. The validity of various published porosity functions and empirical formulae was verified with the use of the experimental data obtained from the glass beads. The best fit was provided by the porosity function n3/(1-n)2. In the case of the estimation of the hydraulic conductivity of uniform glass beads, the best fit was exhibited by formulae published by Terzaghi, Kozeny, Carman, Zunker and Chapuis et al.

scholarly journals Comparison of Hydraulic Conductivity Values Obtained from Empirical Formulae and Laboratory Experiments

2020 ◽  
Vol 68 (4) ◽  
pp. 669-678
Author(s):  
Mario Hala ◽  
Lubomír Petrula ◽  
Zakaraya Alhasan
Keyword(s):  
Experimental Data ◽  
Hydraulic Conductivity ◽  
Laboratory Experiments ◽  
Internal Erosion ◽  
Variable Porosity ◽  
Groundwater Flow Regime ◽  
Series Of Experiments ◽  
Different Grain Size ◽  
Good Agreement

Hydraulic conductivity determination plays an essential role in the investigation of groundwater flow regime which can then influence many field problems such as pumping capabilities in the area, transport of contaminant or heat and soil internal erosion. Numerous equations based on dimensional analysis or experimental measurements have been published since the end of the 19th century for the determination of hydraulic conductivity. However, not all of these formulae are applicable for every material and all of them bring some uncertainty in the value of hydraulic conductivity. This paper contains a description of experimental research carried out concerning the determination of hydraulic conductivity for four types of sand with different grain size distribution curves and variable porosity. Obtained values of hydraulic conductivity ranged from 1 × 10-4 to 4 × 10-3 according to the sample porosity. The series of experiments consisted of 160 separate tests conducted in order to obtain relevant statistical sets. In this paper, the experimental data are discussed and compared with hydraulic conductivities obtained from 6 empirical formulae recommended in a previous study. The comparison showed that some empirical formulae provide a good agreement with the experimental data (the most precise were formulae published by Terzaghi and by Sauerbrey). However, some formulae showed high deviation from measured data (formula published by Zamarin).

scholarly journals Mathematical modeling and determination of thermodynamic properties of jabuticaba peel during the drying process

2016 ◽  
Vol 20 (6) ◽  
pp. 576-580 ◽  
Author(s):  
Cristian F. Costa ◽  
Paulo C. Corrêa ◽  
Jaime D. B. Vanegas ◽  
Fernanda M. Baptestini ◽  
Renata C. Campos ◽  
...  
Keyword(s):  
Experimental Data ◽  
Thermodynamic Properties ◽  
Drying Process ◽  
Drying Temperature ◽  
Air Temperatures ◽  
Nutritional Qualities ◽  
Forced Air ◽  
Air Circulation ◽  
Best Fit

ABSTRACT Jabuticaba is a fruit native of Brazil and, besides containing many nutritional qualities, it also has a good field for use in products such as flour for cakes and biscuits, juice, liqueur, jelly and others. This study aimed to model the drying kinetics and determine the thermodynamic properties of jabuticaba peel at different drying air temperatures. Ripe fruits of jabuticaba (Myrciaria jaboticaba) were collected and pulped manually. Drying was carried out in a forced-air circulation oven with a flow of 5.6 m s-1 at temperatures of 40, 50, 60 and 70 °C. Six mathematical models commonly used to represent the drying process of agricultural products were fitted to the experimental data. The Arrhenius model was used to represent the drying constant as a function of temperature. The Midilli model showed the best fit to the experimental data of drying. The drying constant increased with the increment in drying temperature and promoted an activation energy of 37.29 kJ mol-1. Enthalpy and Gibbs free energy decreased with the increase in drying temperature, while entropy decreased and was negative.

Experimental Design of Surface Modification of Expanded Obsidian and Determination of Water Sorption Capacity

2014 ◽  
Vol 1020 ◽  
pp. 823-826
Author(s):  
G.Sh. Hovsepyan ◽  
M.A. Kalantaryan ◽  
T.V. Yedoyan
Keyword(s):  
Experimental Data ◽  
Surface Modification ◽  
Sorption Capacity ◽  
Water Sorption ◽  
Structural Changes ◽  
Ir Spectrometry ◽  
Water Capacity ◽  
Series Of Experiments ◽  
Water Sorption Capacity

The aim of this paper is to study the possibility of expanded obsidian and its modified product use for oil sorption, in that tetraethoxisilane (TEOS) has been used as a modifier. The optimal concentration of the modifier was determined by 50 per cent weight of expanded obsidian. The expanded obsidian was previously activated with 0,1 M solution of hydrochloric acid. IR spectrometry was used to characterise structural changes in the modified expanded obsidian samples. To determine water sorption capacity a series of experiments has been carried out. The analysis of obtained experimental data showed that after surface modification of expanded obsidian water capacity is reduced 3 times after the surface modification of EO.

scholarly journals Determination of the hygroscopic equilibrium and isosteric heat of aji chili pepper

2017 ◽  
Vol 21 (12) ◽  
pp. 865-871 ◽  
Author(s):  
Ednilton T. Andrade ◽  
Vitor G. Figueira ◽  
Luciana P. Teixeira ◽  
José H. da S. Taveira ◽  
Flávio M. Borém
Keyword(s):  
Experimental Data ◽  
Moisture Content ◽  
Isosteric Heat ◽  
Chili Pepper ◽  
Sorption Behavior ◽  
Activity Levels ◽  
Air Humidity ◽  
Relative Air Humidity ◽  
Best Fit

ABSTRACT This study focuses on the determination of the hygroscopic equilibrium and isosteric heat of the aji chili pepper (Capsicum baccatum) under different controlled temperature and relative air humidity conditions. In addition, the objective was to adjust the model among the existing literature models that best represent the isothermal sorption behavior, as well as propose a new model to represent this phenomenon. Having obtained the mathematical models and experimental data, the best model and parameters that represent the hygroscopicity and the isosteric heat satisfactorily was determined. The temperatures used were 30, 55, and 70 °C, with water activity levels from 0.11 to 0.84. The model that best fit the data had a R2 value of 0.97. The integral isosteric heat of sorption for ‘Dedo-de-Moça’ chili pepper within a moisture content from 0.07 to 0.55 (dry basis) ranged from 3641.66 to 2614.38 kJ kg-1.

scholarly journals Analysis of Hydrodynamic Journal Bearings Considering Lubricant Supply Conditions

1993 ◽  
Vol 207 (2) ◽  
pp. 93-101 ◽  
Author(s):  
J C P Claro ◽  
A A S Miranda
Keyword(s):  
Experimental Data ◽  
Mass Flow ◽  
Finite Differences ◽  
Laboratory Tests ◽  
Journal Bearings ◽  
Experimental Measurements ◽  
Supply Pressure ◽  
Load Line ◽  
Performance Predictions

A method of analysis of steadily loaded hydrodynamic journal bearings with a single axial groove (either on the load line or at 90° to the load line) or two diametrically opposed axial grooves is described. The method is based on Elrod's cavitation algorithm (which ensures conservation of mass flow in both the full film and the cavitated regions) and is able to accommodate specified lubricant supply conditions, namely groove size and location and supply pressure. Special attention has been given to the determination of flowrate. The equation governing the distribution of pressure around the bearing has been solved numerically using a finite differences approximation and multi-grid techniques to accelerate the convergence of the solution. Performance predictions of the analysis are compared with published experimental data and with experimental measurements obtained in laboratory tests carried out by the authors. The data used cover all grooving arrangements studied.

scholarly journals Modeling the crystallization kinetics of polymers displaying high levels of secondary crystallization

2021 ◽  
Author(s):  
Catherine A. Kelly ◽  
Mike J. Jenkins
Keyword(s):  
Experimental Data ◽  
Visual Inspection ◽  
Crystallization Process ◽  
Primary Crystallization ◽  
Parallel Model ◽  
Secondary Crystallization ◽  
Multivariable Regression ◽  
Kinetics Of ◽  
Best Fit

AbstractThe isothermal crystallization of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) was evaluated using a range of models, namely, Avrami, simplified Hillier, Tobin, Malkin, Urbanovici–Segal, Velisaris–Seferis, and Hay. Two methods of model evaluation were used: determination of the parameters through traditional double log plots and curve fitting via nonlinear, multivariable regression. Visual inspection of the cumulative crystallization curves, calculation of the R2 value and standard error of the regression, and evaluation of the returned parameters were used to assess which model best describes the experimental data. The Hay model was found to generate the best fit, closely followed by the Velisaris–Seferis parallel model, suggesting that primary and secondary crystallization occur concurrently. The Avrami, Malkin, and Tobin models were found to perform well when the data is restricted to the region where primary crystallization dominates; however, they could not be used to successfully model the entire crystallization process. This work highlights the importance of selecting the most appropriate model for analyzing kinetics, especially when high levels of lamellar thickening and infilling occur during crystallization.

Selection of Adsorbents and Determination of Parameters for the Separation of Glucose, Fructose, Sucrose and Fructooligosaccharides

2010 ◽  
Vol 6 (6) ◽  
Author(s):  
Raquel Cristine Kuhn ◽  
Francisco Maugeri Filho
Keyword(s):  
Experimental Data ◽  
Active Carbon ◽  
The Other ◽  
Isothermal Kinetics ◽  
Nax Zeolite ◽  
Selection Step ◽  
Determination Of Parameters ◽  
Best Fit ◽  
Selection Of

This work aimed to describe the adsorption of sugars (glucose, fructose, sucrose and fructooligosaccharides) employing different adsorbents (celite, active carbon and NaX zeolite) by means of isothermal models. At the adsorbent selection step, the active carbon exhibited a higher affinity for the adsorption of fructooligosaccharides. On the other hand, the adsorbents NaX zeolite and celite presented the highest adsorption stability with glucose, giving values of 1.496 g glucose/g zeolite and 1.35 g glucose/g celite. Therefore, zeolite and celite were the adsorbents selected for the determination of isothermal kinetics and it was shown that the linear model (q*= k.C*) provided the best fit for the experimental data. The temperatures studied were 30, 40 and 50 °C, and the 50°C resulted in the highest partition coefficient (k) for glucose on celite, indicating that higher temperatures benefit sugar adsorption.

scholarly journals Оптические свойства и критические точки наноструктурированных тонких пленок PbSe

2020 ◽  
Vol 54 (6) ◽  
pp. 527
Author(s):  
М.Г. Гусейналиев ◽  
С.Н. Ясинова ◽  
Д.Н. Джалилли ◽  
С.И. Мехтиева
Keyword(s):  
Experimental Data ◽  
Critical Point ◽  
Numerical Differentiation ◽  
Graphical Analysis ◽  
Analysis Program ◽  
Interband Transitions ◽  
Cbd Method ◽  
Point Line ◽  
Best Fit

Spectroscopic ellipsometry (SE) method has been used to investigate the optical properties of nanostructured PbSe thin films obtained by chemıcal bath deposıtıon (CBD) method. For a better resolution of the structure of interband transitions and for determination of critical points, the function obtained by numerical differentiation of the experimental data of the dielectric function is used. The theoretical fitting was carried out using the "Graphical Analysis" program. The best fit ıs obtained with a 2D-critical point line shape (m = 0) for E=2÷3 eV energy region. One critical point corresponding to Eg = 2,5 eV have been determined. This value is attributed to the L4L6 transition of the Brillouin zone.

The Effect of Stress and Warfarin on the Adrenal Gland in Relation to Spontaneous Hemorrhage, as Judged by Measurement of Adrenal Ascorbic Acid and Serum Corticosterone

1971 ◽  
Vol 26 (02) ◽  
pp. 275-288 ◽  
Author(s):  
S Chattopadhyay ◽  
D. D Johnson ◽  
G. J Millar ◽  
L. B Jaques
Keyword(s):  
Ascorbic Acid ◽  
Acid Concentration ◽  
Ascorbic Acid Concentration ◽  
Corticosterone Concentration ◽  
Serum Corticosterone ◽  
Spontaneous Hemorrhage ◽  
Combined Action ◽  
Series Of Experiments ◽  
Pituitary Adrenal Axis

SummaryRats were subjected to the following procedures: No treatment, Stressor (10% NaCl i.p.), Warfarin for 7 days, Stressor followed by Warfarin; and groups were sacrificed at intervals for assessment of spontaneous hemorrhage and of adrenal ascorbic acid concentration. There was no hemorrhage in the no treatment and stressor groups; some hemorrhage in the warfarin group; profound hemorrhage with Warfarin + Stressor. The adrenal ascorbic acid concentration was found to be lower, 8 h and again 5 days after stress, and remained lower in the warfarin + stress animals. Warfarin had no effect on adrenal ascorbic acid level.In another series of experiments in which the stress consisted of an electric current to the cage floor for 6 sec over 15 min, rats were sacrificed daily for determination of serum corticosterone concentration and occurrence of spontaneous hemorrhage. There was a statistically significant increase of serum corticosterone concentration with stress, warfarin and combined warfarin and stress treatments (P< 0.001 for all three variables). There was a significant correlation (r = 0.96 and 0.89, P< 0.01) for serum corticosterone concentration with hemorrhage score and incidence of hemorrhage in stressed rats receiving warfarin, but not in those receiving only warfarin. The results indicate an activation, rather than an exhaustion, of the pituitary-adrenal axis during the combined action of anticoagulant and stress, which results in the development of spontaneous hemorrhage.

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