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Fatemeh Ahmadi-Motamayel,Shahriar Shahriari,Mohammad Taghi Goodarz,Abbas Moghimbeigi,Mina Jazaeri,Parisa Babaei 大韓齒科保存學會 2013 Restorative Dentistry & Endodontics Vol.38 No.3
Objectives: Assessment of dental pain severity is very challenging in dentistry. Previous studies have suggested that elevated salivary alpha amylase may contribute to increased physical stresses. There is a close association between salivary alpha amylase and plasma norepinephrine under stressful physical conditions. The aim of this study was to evaluate the relationship between pain severity and salivary alpha amylase levels in patients with symptomatic irreversible pulpitis. Materials and Methods: Thirtysix patients (20 females and 16 males) with severe tooth pain due to symptomatic irreversible pulpitis were selected. The visual analogue scale (VAS) score was used to assess the pain severity in each patient. Unstimulated whole saliva was collected, and the level of alpha amylase activity was assessed by the spectrophotometric method. Statistical analysis was performed using SPSS 13. Results: The level of alpha amylase was significantly increased in the saliva in association with pain severity assessed by VAS. The salivary alpha amylase was also elevated with increased age and in males. Conclusions: There was a significant correlation between the VAS pain scale and salivary alpha amylase level, which indicates this biomarker may be a good index for the objective assessment of pain intensity.
Computational fluid dynamics studies of dry and wet pressure drops in structured packings
Seyyed Hossein Hosseini,Saeed Shojaee,Goodarz Ahmadi,Mortaza Zivdar 한국공업화학회 2012 Journal of Industrial and Engineering Chemistry Vol.18 No.4
Computational fluid dynamics was used to study the hydrodynamic of structured packings. The results showed that the k–v was a suitable turbulence model for analyzing the flows in structured packings. A simple method was proposed for evaluating the liquid holdup based on the Iliuta and Larachi (2001)model [25], the calculated liquid film thickness in 2D framework, and the empirical correlation of Brito et al. (1994) [26]. The presented method can be used for estimating the wet pressure drop in 3D structured packings for loading region with good accuracy as well as computational economy. The process of liquid film formation was also discussed.
Design parameter study on the performance of lead-acid batteries
Vahid Esfahanian,Amir Babak Ansari,Hassan Bahramian,Pooyan Kheirkhah,Goodarz Ahmadi 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.6
The investigation of design parameters is very helpful for optimizing the capacity of an electrochemical cell, which can be done byboth experimental and numerical methods. In this study, a lead-acid battery has been simulated numerically using the CFD commercialsoftware package FLUENT. The governing equations, including conservation of charge in solid and liquid phases and conservation ofspecies, are solved by developing several user defined functions (UDF). The effect of some basic parameters such as electrode porosity,discharge current density, and width of the electrodes and separator on the cell voltage behavior of a lead-acid battery is investigated. Ithas been shown that increasing the width and porosity of separator has both positive and negative effects on the performance parametersof battery. Furthermore, a thicker PbO2 electrode has a more pronounced effect than a thicker Pb one.
Seyyed Hossein Hosseini,Mahmood Reza Rahimi,Nader Azizi,Goodarz Ahmadi 한국화학공학회 2013 Korean Journal of Chemical Engineering Vol.30 No.3
The hydrodynamics of a vertically vibrating fluidized bed was studied using an Eulerian-Eulerian twofluid model (TFM) incorporating the kinetic theory of granular flow and including the frictional stress effects. Influences of frictional stresses, vibration amplitudes and frequency on behavior of the particles were studied. In the case with vertical vibration, the numerical results showed three regions of solid concentration along the bed height: a low particle concentration region near the bottom of the bed, a high concentration region in the middle of the bed, and a transition region at top of the bed. The accuracy of results was found to be closely related to the inclusion of the frictional stresses. Ability of the two-fluid model for predicting the hydrodynamics of vibrating fluidized beds was discussed and confirmed.
Three-dimensional CFD study of conical spouted beds containing heavy particles: Design parameters
Naimeh Setarehshenas,Seyyed Hossein Hosseini,Mohsen Nasr Esfahany,Goodarz Ahmadi 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.5
The flow behavior of conical spouted beds containing heavy particles that occurs in chemical vapor deposition (CVD) was investigated using the computational fluid dynamics (CFD) approach. A fully Eulerian description of solid and gas phases flows in 3D was used in these simulations. The hydrodynamics parameters including particle velocity, solid flux, and solid volume fraction profiles at different bed levels were evaluated, and the overall behavior of solid particles in the beds was studied. The results showed close agreement with the corresponding experimental data. The effects of cone angle, static bed height, and cone bottom diameter on the hydrodynamic behavior of heavy particles were analyzed and the results were presented. In addition, the effects of flat wall of semi-conical spouted bed (halfcolumn) on the CFD results and performance of the spouted bed were investigated. The hydrodynamic results for the full bed were quite different from those for the half bed geometries. It was also found that the conical spouted bed with the angle of 45o leads to the roughly stable spouting compared to the 30o angle bed. The CFD model also showed that the conical-cylindrical spouted beds operating with heavy particles has the potential for periodic occurrence of choking in the spout zone.
Influence of gas exhaust geometry on flow pattern, performance, and erosion rate of a gas cyclone
Parvaz Farzad,Hosseini Seyyed Hossein,Bastan Ahmad Reza,Foroozesh Jamal,Babaoğlu Nihan Uygur,Elsayed Khairy,Ahmadi Goodarz 한국화학공학회 2023 Korean Journal of Chemical Engineering Vol.40 No.7
The effect of gas exhaust shape on the performance, flow pattern, and erosion rate of a gas cyclone was investigated using a numerical model. The results show that the shape of the gas exhaust affects the movement of the vortex core in the gas cyclone. With a change in the shape of the exhaust gas, the axial and tangential velocities changed in the cyclone. The highest turbulent kinetic energy in cyclones was found in the gas exhaust region. The results showed that the diamond gas exhaust exhibited the highest turbulent kinetic energy among the other shapes. In the cases of diamond and square gas exhausts, the size of the Rankine vortex was decreased, leading to a reduction in the centrifugal force of the gas flow and, thereby, cyclone separation efficiency. The lowest erosion rate and highest separation efficiency were found for the cyclone with a circular gas exhaust.