Average Absolute Deviation Percent Research Articles

Compressed Liquid Densities of Binary Mixtures of 1-Butanol and Diethylene Glycol Dimethyl Ether from (283 to 363) K at Pressures up to 100 MPa

The compressed liquid densities of binary mixtures of 1-butanol and diethylene glycol dimethyl ether (diglyme) have been measured over the temperature range from (283 to 363) K and at pressures up to 100 MPa covering the whole mole fraction of x1-butanol = (0, 0.3116, 0.5469, 0.7308, 0.8787, 1). The measurements were carried out using a high-pressure vibrating-tube densimeter with the combined expanded uncertainty (k = 2) of 0.6 kg·m–3. The experimental data were correlated using the modified Tait equation with an absolute average percentage deviation lower than 0.015% for each composition of the mixtures.

Efficient Algorithm for the Prediction of Pressure–Volume–Temperature Properties of Crude Oils Using the Perturbed-Chain Statistical Associating Fluid Theory Equation of State

A new simplified approach is presented for characterizing crude oils using the perturbed-chain version of the statistical associating fluid theory equation of state (PC-SAFT EoS). The new approach models the liquid phase in crude oil as one pseudocomponent called the “single liquid fraction” (SLF). The SLF approach requires a single fitting parameter called aromaticity (γSLF) which is fitted to the experimental bubble point and density at saturation. Simulation results for 10 light crudes from the Middle East are presented in this work and compared to 2078 data points for the predictions of constant composition expansion (CCE), differential liberation (DL), separator test, and swell test experiments. It is found that the model predictions of density are the most accurate, with an average absolute percent deviation (AAPD) of 0.5% in the CCE, 0.7% in the DL, 0.8% in the separator test, and 2.1% in the swell test. The swell test study included modeling of blends of live oil with different gases such as lean ...

Thermodynamics of Viscous Flow of tert-Butanol with Butylamines: UNIFAC–VISCO, Grunberg–Nissan and McAllister Three Body Interaction Models for Viscosity Prediction and Quantum Chemical (DFT) Calculations

Thermodynamic activation parameters, enthalpies (ΔH‡), entropies (ΔS‡) and Gibbs energies (ΔG‡) for viscous flow of the systems tert-butanol (TB)+n-butylamine (NBA), TB+di-n-butylamine (DBA) and TB+tri-n-butylamine (TBA) have been calculated from measured density and viscosity data at temperatures ranging from 303.l5 to 323.15 K over the composition range 0 ≤ x2 ≤ 1, where x2 is the mole fraction of TB. For all systems, the corresponding excess properties ΔH‡E, ΔS‡E and ΔG‡E have been determined, which are negative in the whole range of composition. The observed negative excess activation properties have been accounted for in terms of dispersive forces and H-bonding. The derived properties are well represented by fourth degree polynomial equations whereas the excess properties could be fitted to third degree Redlich–Kister polynomial equations. Furthermore, the viscosities have been predicted by using the UNIFAC–VISCO model, Grunberg–Nissan model and McAllister three-body interaction model. The UNIFAC–VISCO model and Grunberg–Nissan model do not show good agreement with the experimental data, whereas the McAllister three-body interaction model shows excellent agreement for all three systems, with small average absolute percent deviations (AAD% = 0.6–2.3). The DFT-B3LYP method with the 6-311 G (d, p) basis set has been employed for the optimization of the geometry and calculation of the total energies of the pure compounds and their binary complexes.

Correlating ionic liquids density over wide range of temperature and pressure by volume shift concept

The main purpose of this paper is the use of the conventional Peng–Robinson equation of state (PR EoS) and the concept of volume shift to correlate and predict pure ionic liquids (ILs) density in a wide range of temperature and pressure. A total number of 67 pure ILs (5020 data points) including different cations and anions were used in this study over temperature and pressure range of 273.15–473.15K and 0.1–205MPa. At first, the volume shift parameter (c) of 67 ILs in any temperature and pressure were optimized using genetic algorithm. An equation similar to Gardas and Coutinho (R. L. Gardas, J. A. P. Coutinho, Fluid Phase Equilibr. 263 (2008) 26–32) was used for c parameter and finally a generalized correlation was proposed for c as a function of temperature, pressure and critical molar volume. This equation was also used in predicting densities of eight new ILs not included in correlation section and it was able to improve the PR EoS prediction and reducing the error with respect to experimental data. Considering the importance of density in engineering, using this simple equation with the VTPR improves ILs density prediction and calculation, saves time and increases the accuracy engineering design. The average absolute percent deviation (AAPD) of the volume translated PR (VTPR) EoS and the conventional PR EoS were equal to 2.19% and 12.98%, respectively.

Compressed Liquid Viscosity of 2-Methylpentane, 3-Methylpentane, and 2,3-Dimethylbutane at Temperatures from (273 to 343) K and Pressures up to 40 MPa

The compressed liquid viscosities of 2-methylpentane, 3-methylpentane, and 2,3-dimethylbutane were measured using a vibrating-wire viscometer over the temperature range of (273 to 343) K and at pressures up to 40 MPa. The combined expanded uncertainty of the reported viscosity is about 2% with a confidence level of 0.95 (k = 2). An empirical Andrade–Tait equation was used to correlate the viscosity as a function of temperature and pressure with average absolute percentage deviations of 0.19%, 0.23%, and 0.25%, respectively.

Ultrasonic assisted removal of methylene blue on ultrasonically synthesized zinc hydroxide nanoparticles on activated carbon prepared from wood of cherry tree: Experimental design methodology and artificial neural network

Abstract The zinc hydroxide nanoparticles was synthesized and loaded on activated carbon prepared from wood of cherry tree (Zn (OH)2-NPs-AC). Prepared NP based adsorbent was used to remove methylene blue (MB) from aqueous medium. The dependency of MB concentration, pH, adsorbent doses and sonication time on the extent of adsorption was investigated and optimized using response surface methodology (RSM) based on central composite design. Analysis of variance (ANOVA) was made to calculate coefficient of determination (R2). The best operation of conditions were determined for MB concentration (12.5 mg L− 1), pH (6), adsorbent mass (0.025 g) and sonication time (6.5 min). In addition, all the experimental data was used to train the artificial neural network (ANN) model. Performance evaluation of the ANN model by means of squared error (MSE), average absolute percent deviation (AAD%) and correlation coefficient (R2) depicted the experimental value of MSE = 0.0529, AAD = 0.1894% and R2 = 0.98. These values were better than that of obtained from RSM model (MSE = 2.7107, AAD = 1.470%, R2 = 0.9142). It was noted that the equilibrium isotherm data followed Langmuir model with high adsorption capacity. The adsorption kinetics was efficiently represented by combination of pseudo second order and intraparticle diffusion models.

A study of viscometric, optical and interfacial properties of binary and ternary liquid mixtures

Transport, optical and interfacial (surface tension) properties, have been evaluated for ternary system (2-propanol+tetrahydropyran+2,2,4 trimethylpentane) and its constituent binaries at 4 different temperatures ranging between 293.15 and 323.15K. Viscosity, an important transport property, has been computed by employing 15 approaches. Refractive index, an optical and transport property of due significance has also been evaluated using 10 approaches. Surface tension, an interfacial property, has also been computed by five different models. A new approach has been put to test for predicting refractive index and surface tension, for the first time, to binary systems and has been extended for ternary system under investigation. The obtained results have been compared with the predictive and correlative approaches by taking absolute average percentage deviation (AAPD) as the criterion. Further, excess Gibbs free energy of activation of viscous flow(ΔG*E) and excess coefficient of thermal expansion (αE) have also been elucidated to predict the nature of interactions for all the four systems to get a better understanding of the various intermolecular interactions taking place thereof. The present investigation attempts to develop a universal equation for evaluation of thermophysical properties.

Thermodynamic properties of biodiesel and petro-diesel blends at high pressures and temperatures. Experimental and modeling

One of the solutions to greenhouse gases emission is the use of biodiesels, since their mixtures with petro-diesel can be used as fuel in existing diesel engines without additional corrections in engines’ design. In order to estimate engine performance and increase its efficiency, it is necessary to know the basic properties of fuels under different operating conditions, and among the most important ones are density and viscosity. Therefore, the densities of pure petro-diesel, as well as densities of its blends with sunflower oil methyl and ethyl esters, in the ratio of 10vol% and 20vol% of the biodiesel, at temperatures 293.15–413.15K and at pressures of 0.1–60MPa, are presented here. Measurements were taken at an Anton Paar DMA HP densimeter. For the device calibration the classical calibration method with one reference fluid was applied. Also, for the same samples, the viscosities at 288.15–373.15K and the refractive indices at 288.15–343.15K at atmospheric pressure were measured. Measured densities decrease linearly as temperature rises along isobars and increase with pressure rise at a constant temperature for all examined samples. Refractive index, also, decreases linearly with temperature rise, while viscosity decreases exponentially with increase in temperature. Densities and refractive indices are higher for blends with sunflower oil methyl esters than with its ethyl esters, opposite to viscosity. Densities of blends increase linearly with rise in biodiesel share, while the increase of viscosity is exponential. Density data were fitted to the modified Tammann-Tait equation and the obtained results were used for calculation of derived thermodynamic properties such as the isothermal compressibility, the isobaric thermal expansivity, the internal pressure and the difference between specific heat capacity at constant pressure and the specific heat capacity at constant volume. The absolute average percentage deviations of the measured densities from those calculated using the modified Tammann-Tait equation were about 0.01%, for all studied samples, assessing positively the correlation procedure. The dependence of the measured and calculated properties of the blends on biodiesel amount was also examined.

Solid-liquid equilibrium of n-alkanes using Global-TPT2 equation of state

An equation of state (EOS) in the framework of thermodynamic perturbation theory (TPT) is applied to the systems containing n-alkanes and the wax deposition phenomena. The EOS used is derived by Alavi and Feyzi (J. Chem. Phys. 2013, vol.139, 074104) and is comprised of a perturbed-chain reference term based on second-order thermodynamic perturbation theory (TPT2), followed by a square-well perturbation contribution. Since the EOS is developed without any phase related assumptions, it can describe vapor, liquid and solid phases. For this reason we have called the EOS Global-TPT2. The pure component parameters are adjusted to pure n-alkane compounds performing linear optimization algorithm. Solubility temperature of some heavy n-alkanes in the n-hexane and n-heptane solvents is evaluated. Good agreement with the experimental data is observed with Average Absolute Relative Percent Deviation (%AAD) of lower than 2 by adjusting only one binary interaction parameter. In addition, the wax appearance temperature and the amount of precipitated wax are predicted using the Global-TPT2 EOS for two North Sea oil samples and also samples composed of methane plus ternary waxy systems. In all these calculations the same EOS is used for both liquid and solid phases. Even though some simplifying assumptions are applied, the model is proved to be capable of adequately describing the systems containing solid phase.

SU‐F‐J‐95: Impact of Shape Complexity On the Accuracy of Gradient‐Based PET Volume Delineation

Purpose:Explore correlation of tumor complexity shape with PET target volume accuracy when delineated with gradient‐based segmentation tool.Methods:A total of 24 clinically realistic digital PET Monte Carlo (MC) phantoms of NSCLC were used in the study. The phantom simulated 29 thoracic lesions (lung primary and mediastinal lymph nodes) of varying size, shape, location, and 18F‐FDG activity. A program was developed to calculate a curvature vector along the outline and the standard deviation of this vector was used as a metric to quantify a shape's “complexity score”. This complexity score was calculated for standard geometric shapes and MC‐generated target volumes in PET phantom images. All lesions were contoured using a commercially available gradient‐based segmentation tool and the differences in volume from the MC‐generated volumes were calculated as the measure of the accuracy of segmentation.Results:The average absolute percent difference in volumes between the MC‐volumes and gradient‐based volumes was 11% (0.4%–48.4%). The complexity score showed strong correlation with standard geometric shapes. However, no relationship was found between the complexity score and the accuracy of segmentation by gradient‐based tool on MC simulated tumors (R2 = 0.156). When the lesions were grouped into primary lung lesions and mediastinal/mediastinal adjacent lesions, the average absolute percent difference in volumes were 6% and 29%, respectively. The former group is more isolated and the latter is more surround by tissues with relatively high SUV background.Conclusion:The complexity shape of NSCLC lesions has little effect on the accuracy of the gradient‐based segmentation method and thus is not a good predictor of uncertainty in target volume delineation. Location of lesion within a relatively high SUV background may play a more significant role in the accuracy of gradient‐based segmentation.

SU-F-T-362: Quantification and Modelling of the Ionization Chamber Simulation Effective Points On Monaco Treatment Planning System

Purpose: Because of statistical noise in Monte Carlo dose calculations, effective point doses may not be accurate. Volume spheres are useful for evaluating dose in Monte Carlo plans, which have an inherent statistical uncertainty.We use a user-defined sphere volume instead of a point, take sphere sampling around effective point make the dose statistics to decrease the stochastic errors. Methods: Direct dose measurements were made using a 0.125cc Semiflex ion chamber (IC) 31010 isocentrically placed in the center of a homogeneous Cylindric sliced RW3 phantom (PTW, Germany).In the scanned CT phantom series the sensitive volume length of the IC (6.5mm) were delineated and defined the isocenter as the simulation effective points. All beams were simulated in Monaco in accordance to the measured model. In our simulation using 2mm voxels calculation grid spacing and choose calculate dose to medium and request the relative standard deviation ≤0.5%. Taking three different assigned IC over densities (air electron density(ED) as 0.01g/cm3 default CT scanned ED and Esophageal lumen ED 0.21g/cm3) were tested at different sampling sphere radius (2.5, 2, 1.5 and 1 mm) statistics dose were compared with the measured does. Results: The results show that in the Monaco TPS for the IC using Esophageal lumen ED 0.21g/cm3 and sampling sphere radius 1.5mm the statistical value is the best accordance with the measured value, the absolute average percentage deviation is 0.49%. And when the IC using air electron density(ED) as 0.01g/cm3 and default CT scanned EDthe recommented statistical sampling sphere radius is 2.5mm, the percentage deviation are 0.61% and 0.70%, respectivly. Conclusion: In Monaco treatment planning system for the ionization chamber 31010 recommend air cavity using ED 0.21g/cm3 and sampling 1.5mm sphere volume instead of a point dose to decrease the stochastic errors. Funding Support No.C201505006

A new generalized model for predict speed of sound of refrigerants

In consideration of physical and chemical properties of pure substances, speed of sound is one of important quantity which can used to calculate many of other thermo-physical properties such as isothermal compressibility, Joule-Thomson coefficient, isobaric heat capacity and etc. These thermo-physical properties are the main parameters in industrial and chemical processes. Development of accurate models for thermodynamic properties computation such as speed of sound is well expected above all in those fields where very high performance calculations have to be reached. In this present work, a new generalized model as a function of reduced temperature and reduced density is proposed to correlate speed of sound of methane, ethane, propane and butane halogenated refrigerants. Speed of sounds have been calculated and compared with data reported in literatures for 5600 data points of 28 refrigerants, and the overall average absolute percentage deviation of 0.92%. The source of speed of sound data used in this study is the NIST Chemistry WebBook.

Experimental and Theoretical Investigation of Polymeric Drag Reducing Agent in Turbulent Pipe Flow

In the present work, the drag reduction effectiveness of water soluble Carboxyl methyl cellulose (CMC) was studied as a function of polymer concentration and flow rate. Drag reduction results were assessed by measuring pressure drop over a one meter test section from the selected pipe. The effect of additives concentration was investigated over a range of 0 – 85 wppm, the solvent (water) flow conditions that were studied included higher flow rates. The experimental work was performed in a constructed re–circulating closed loop system. Maximum drag reduction percent (MDR%) of 17.3 % was obtained by using 85 wppm of CMC. The friction factor was calculated from experimental data with an acceptable average absolute percent Deviation. Correlation equation for fanning friction factor was suggested as a function of Re. The drag reduction results have been correlated based on a modification of a theoretical model available in the literature. The functional form of the model requires knowledge of the velocity profile, ratio of mixing length, friction factor, and the additive concentration as dependent variables.

Accurate Prediction of the Surface Tensions of Ionic Liquids–Amines–Water Mixtures Regarding CO2 Recovery and Sequestration Processes

A support vector machine (SVM) model is presented concerning accurate prediction of the surface tension of the complex mixtures of ionic liquids (ILs)–amines–water using the most important types of amines employed in the gas sweetening plants, such as monoethanolamine, diethanolamine, and methyldiethanolamine. Different ILs, such as [bmim] [BF4], [bmim] [DCA], [mmim] [dmp], [emim] [dep], [bmim] [BF4], [bmim] [Br], [bmim] [BF4], and [bmim] [Br], are considered in the presented model. The effects of most important influencing parameters, such as temperature and mass fraction of amines and ILs, on the surface tension of the aqueous mixtures of ILs and amines are well represented. A comparison of the presented model and the most important models reveals that the suggested SVM model has better performance in terms of accuracy and generalizability. The percentage average absolute deviation between the predicted and experimental surface tensions is about 0.44% suggesting the superiority of the presented model over wide ranges of temperatures and species concentrations.

Measuring solubility of hydrogen sulphide in aqueous blends of N-methyldiethanolamine and 2-((2 aminoethyl)amino)ethanol and correlating by the Deshmukh–Mather model

The solubility of hydrogen sulphide (H2S) in aqueous solution of N-methyldiethanolamine (MDEA) in the presence of different mole ratios of 2-((2-aminoethyl)amino)ethanol (AEEA) at low and medium pressures was obtained. The total concentrations of all the solutions have been fixed equal 3.36mol·L−1 (5.37 total moles of amines·kg−1 water). The mole ratio of [AEEA]/[MDEA] (mole ratio of AEEA per MDEA in fresh solutions) was set to 0.05, 0.10 and 0.125. The experimental total pressure varied from (7.3 to 1500) kPa and the temperatures were set to (313.2, 328.2, 343.2 and 358.2)K. The experimental values are presented as the total pressure against acid gas loading (mole H2S/total moles of amine). The results show that the AEEA concentration can improve absorption capacity of MDEA aqueous solution as the mole ratio [AEEA]/[MDEA] increases at constant total concentration. The Deshmukh–Mather model and Peng–Robinson equation of state were used for liquid and vapour phases, respectively to correlate the solubility of H2S in aqueous mixtures of AEEA and MDEA. The overall average absolute percent deviation (AAD%) in calculating the total pressure as a function of H2S loading obtained 8.15% for (AEEA–MDEA–H2S–H2O) quaternary system at the entire temperature and pressure ranges in this work.

A semi-analytical scheme to estimate Secchi-disk depth from Landsat-8 measurements

Abstract The newly developed semi-analytical scheme (Lee et al., 2015a) for remote sensing of the Secchi disk depth (ZSD, m) was modified and applied to Landsat-8 data to obtain high-spatial-resolution map of water clarity. In order to implement the quasi-analytical algorithm (QAA) for the derivation of absorption and backscattering coefficients from Landsat-8 data, which are key optical properties for the estimation of ZSD, the representative wavelengths of Landsat-8 bands in the visible domain are verified; so are the absorption and backscattering coefficients of pure water for these bands. This semi-analytical scheme was then applied to a dataset having both in situ measurements of ZSD (~ 0.1–30 m) and remote-sensing reflectance and found that the estimated ZSD from remote sensing matches measured ZSD very well (R2 = 0.96, average absolute percent difference ~ 17%, N = 197). This scheme was further applied to a Landsat-8 image collected in an estuary to obtain high-spatial resolution ZSD map, and the obtained spatial distribution of ZSD is found quite consistent with in situ measurements and visual observations. These results indicate an important application of Landsat data — to provide reliable high-resolution water clarity product of bays, estuaries, and lakes with a unified mechanistic system.

CCSD(T)/CBS fragment-based calculations of lattice energy of molecular crystals.

A comparative study of the lattice energy calculations for a data set of 25 molecular crystals is performed using an additive scheme based on the individual energies of up to four-body interactions calculated using the coupled clusters with iterative treatment of single and double excitations and perturbative triples correction (CCSD(T)) with an estimated complete basis set (CBS) description. The CCSD(T)/CBS values on lattice energies are used to estimate sublimation enthalpies which are compared with critically assessed and thermodynamically consistent experimental values. The average absolute percentage deviation of calculated sublimation enthalpies from experimental values amounts to 13% (corresponding to 4.8 kJ mol(-1) on absolute scale) with unbiased distribution of positive to negative deviations. As pair interaction energies present a dominant contribution to the lattice energy and CCSD(T)/CBS calculations still remain computationally costly, benchmark calculations of pair interaction energies defined by crystal parameters involving 17 levels of theory, including recently developed methods with local and explicit treatment of electronic correlation, such as LCC and LCC-F12, are also presented. Locally and explicitly correlated methods are found to be computationally effective and reliable methods enabling the application of fragment-based methods for larger systems.

Surface Tension and Liquid Viscosity of R32+R1234yf and R32+R1234ze

The surface tension and liquid viscosity of two binary refrigerant mixtures 1,1,1,2-tetrafluoroethane (R32) (1) + 2,3,3,3-tetrafluoroprop-1-ene (R1234yf) (2) and R32 (1) + trans-1,3,3,3-tetrafluoroprop-1-ene (R1234ze) (2) have been measured from 293 K to the critical point by using the surface light scattering (SLS) method. The experimental data were correlated as a function of temperature and mole fraction of the pure components. For the surface tension of R32+R1234yf and R32+R1234ze, the average absolute deviations are 0.053 and 0.029 mN·m–1, respectively. As for the liquid viscosity, the relative percentage average absolute deviations are 0.86 and 1.01%, respectively.

A modified Frenkel approach for viscometric prediction of binary and multicomponent liquid mixtures

Comparison of absolute average percentage deviations (AAPD) values of modified Frenkel with different approaches for binary, ternary and quaternary systems.

Toward an intelligent approach for H2S content and vapor pressure of sour condensate of south pars natural gas processing plant

In this study, artificial neural network is employed to develop a model to predict process output variables of an industrial condensate stabilization plant. The developed model is evaluated by process operating data of south pars natural gas processing plant located Asaluyeh/Iran. A large dataset of 4 variables consisting of temperature and pressure of the stabilization column in addition to Ried Vapor Pressure (RVP) and H2S content of the processed condensate is utilized to train the network. In order to determine the optimized topology and decision parameters of the network, the values of Mean Square Error (MSE), Mean Absolute Error (MAE) and the coefficient of determination (R2) are minimized by the method of trial and error. Since precision of ANN model is dependent on the amount of training data used, the extensive set of samples applied in this work can offer accurate reliable predictions. Model output is compared to actual data of the plant and the values of Average Absolute Deviation percent (ADD%) are reported as 1.6 for RVP and 3.8 for H2S concentration.