Khezrian M.,Shahid Chamran University |
Hajidavalloo E.,Shahid Chamran University |
Shekari Y.,Yasuj University
Chemical Engineering Research and Design | Year: 2015
Modeling and simulation of gas-liquid two-phase flow in under-balanced drilling (UBD) operation is very important in order to accurately predict the bottom-hole pressure (BHP) and other parameters of two-phase flow. In this paper one-dimensional form of steady-state two-fluid model in the Eulerian frame of reference is used to simulate the two-phase flow in the UBD operation. Simulation is performed to calculate the parameters such as pressure, volume fraction and velocities of two phases at different flow regimes, namely bubbly, slug and churn turbulent flow. The governing equations along with appropriate constitutive relations form a system of coupled ordinary differential equations (ODEs) which are solved using the well-known iterative Newton method. The effect of gas and liquid injection flow rates and also the choke pressure on the wellbore pressures, particularly on the BHP are investigated numerically. In order to validate the results of the current two-fluid model, they are compared with the actual field data and also with the results of the WELLFLO software using different mechanistic models. The comparisons show that the two-fluid model can accurately predict the BHP and other two-phase flow parameters. © 2014 The Institution of Chemical Engineers.
Ghaedi M.,Yasouj University |
Jaberi S.Y.S.,Yasouj University |
Hajati S.,Yasuj University |
Montazerozohori M.,Yasouj University |
And 2 more authors.
IEEE Sensors Journal | Year: 2015
A novel carbon paste electrode (CPE) based on 2,2-(ethane 1,2-diylbis (azanylylidene)) bis (ethan-1-yl-1-ylidene)) diphenol (L) was prepared for selective determination of trace amount of Pb2+ ion. The effects of individual variables, such as amounts of L, sodium tetraphenylborate (NaTPB), graphite powder, and Nujol as well as their possible interactions were investigated and optimized using central composite design under response surface methodology. Optimum composition of carbon paste was set as 100-mg Nujol and the mass (milligram) ratio of 209/4/6 for graphite powder: NaTPB: carrier, respectively. Such composition was found to be led to significant enhancement in the selectivity and sensitivity of the CPE toward Pb2+ ions over a wide concentration range of 3.7 × 10-7-1 × 10-2 mol L-1 with detection limit of 1.5 × 10-7 mol L-1 and a Nernstian slope of 30.7±1.56 mV/decade of Pb2+ concentration. Negligible significant change in response was seen over wide pH range of 4-6 with response time lower than 14 s. The good selectivity of the CPE for Pb2+ ion toward other metal ions was confirmed by the potentiometric selectivity coefficients. Finally, to be practical, these electrodes were accurately and repeatability used for the determination of Pb2+ ions in real water sample. © 2015 IEEE.
Mohammadzadeh A.,University of Mazandaran |
Samadi-Maybodi A.,University of Mazandaran |
Khodadoust S.,Yasuj University
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy | Year: 2013
(Figure Presented) Quercus brantii acorn is rich of some useful mineral elements such as K, Fe and Zn. The content of these mineral elements in Quercus are dependent on their region and environmental conditions. Q. brantii grown naturally in different regions of Iran especially in Kohgiloye va Boyer Ahmad province (southwestern of Iran). In this study total concentration of Fe, Zn and K elements were determined using atomic absorption and emission spectroscopy in fruits, leaves of Q. brantii and also in the soils where this plant was grown. Statistical evaluation (ANOVA test) was employed for all measurements. Results confirmed that the concentration of elements in fruit and leave depended on area which the plant is growth. The transport factor of elements was also considered. © 2013 Elsevier B.V. All rights reserved.
Rabani S.M.,Yasuj University of Medical Sciences |
Moosavizadeh A.,Yasuj University
Nephro-Urology Monthly | Year: 2012
Background: A review of the related medical journals indicates that there is no definite evidence- based option for managing large proximal ureteral stones, although many procedures such as transureteral lithotripsy (TUL), shock wave lithotripsy (SWL), percutaneous nephrolithotripsy, laparoscopic ureterolithotomy, and open ureterolithotomy are currently used to treat this urological problem. Objectives: In this study, we tried to determine the most appropriate treatment plan for proximal ureteral stones larger than 12 mm by comparing the two most commonly used procedures. Patients and Methods: Between February 2005 and April 2011, 62 patients including 40 males and 22 females (mean age 39.5 years, range 19 to 64) with proximal ureteral stones larger than 12 mm (12-26 mm) with a mean size of 17.64 mm were prospectively divided into two groups consisting of 32 patients who underwent TUL (group A) and 30 who underwent SWl (group B). In unsuccessful cases, repeat SWl or TUL was planned. Patients who could not tolerate the lithotomy position, younger than 18 years, had undergone coagulopathy, had concurrent renal and ureteral stones, were pregnant, or had sepsis were excluded from this study. Results: Stone access was successful in 28 patients and the treatment was efficient in 18 patients (56.25%) in group A. For the patients with successful stone access but unsuccessful TUL, a DJ was inserted and a second ureteroscopic intervention was performed. The second intervention was successful in 7 patients (21.87). SWl was successful in 14 patients (46.66%) in the first attempt and in 7 additional patients in the second intervention (23.33%). Conclusions: In this study, we showed different success rates for SWl and TUl because of the larger size of the stones. We achieved a success rate of 56.25% in the first attempt in the TUl group, and the overall success rate (after the second TUL) was 78.12%. In comparison, the SWL group had a success rate of 46.66% in the first attempt, and the overall success rate (after the second SWL) was 69.96%. © 2012 Kowsar Corp. All rights reserved.
Yoosefian M.,Kerman Graduate University of Technology |
Chermahini Z.J.,Yasuj University |
Raissi H.,Birjand University |
Mola A.,Kerman Medical University |
Sadeghi M.,Institute for Advanced Studies in Basic Sciences
Journal of Molecular Liquids | Year: 2015
The results of a detailed DFT (B3LYP) and ab initio (HF and MP2) investigation on one of the amino-imino tautomers and its derivatives are presented here. The energy, geometrical parameters and vibrational frequencies of 2-amino-1,3,4-thiadiazole tautomerization in the gas phase, water, THF and DMSO solutions were calculated using 6-311++G(d,p), 6-311G(d) and 6-31+G(d,p) basis sets. The solvent effect was explored using the PCM method and the related conformers have been fully optimized at the B3LYP/6-311++G∗∗ level of theory. For the investigated molecule, proton-transfer from N to N and from N to C occurred, which leads to three tautomers: 2-amino-1,3,4-thiadiazole (A), 2(3H)-imino-1,3,4-thiadiazole (B) and 2(5H)-imino-1,3,4-thiadiazole (C). For B and C, geometrical isomerism (E and Z) was also considered. This leads to five isomers: A, B1, B2, C1 and C2 for each derivative. However, all calculations evidently show that isomer A strongly or solely dominates and dictates the structure of 2-amino-1,3,4-thiadiazoles. Substituents and solvents have no effect on the tautomeric preferences. ©2014 Elsevier B.V. All rights reserved.