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Mohammad Salman,Sung Chul Kim 대한설비공학회 2021 대한설비공학회 학술발표대회논문집 Vol.2021 No.6
An experimental analysis was accompanied to consider the influence of convective heat transfer and airflow characteristics through an impingement jet solar heat collector with indented dimple roughness geometry on the absorber plate (CJISHC). The experimental outcomes comprised the arc angle (α<SUB>d</SUB>) from 30° to 75°, the relative indented roughness pitch (p/D<SUB>h</SUB>) from 0.269 to 0.810, the relative indented roughness height (e/D<SUB>h</SUB>) from 0.016 to 0.0267. The inclusive performance of CJISHC was effectively evaluated by fluctuating the Reynolds number (Re) from 3000 to 21000. The Nusselt number (Nu<SUB>ct</SUB>) increases with the increase in Re, as predicted. It is observed that the value of Nu<SUB>ct</SUB> is a strong function of α<SUB>d</SUB>. However, the values of Nu<SUB>ct</SUB> for the indented dimples on the absorber plate are significantly higher than the values for the smooth absorber plate. The combined friction factor (ff<SUB>ct</SUB>) reaches its optimum value at an e/Dh of 0.0267, while the minimum value is at 0.016. The experimental outcomes confirm that the maximum thermohydraulic performance (η<SUB>ct</SUB>) augmentation value of 2.15 was obtained at αd = 60°, p/D<SUB>h</SUB>=0.269, and e/D<SUB>h</SUB>=0.0267 compared to conventional SHC. These experimental values were used to develop the correlations for the Nu<SUB>ct</SUB> and friction factor ff<SUB>ct</SUB> as a function of the indented dimpled roughness parameters.
Mohammad Bany Salman,Minkyu Park,Mosab Jaser Banisalman 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.12
In this study, we employed molecular dynamics simulations to explore the influence of strain on primary defect formationand interstitial dislocation loop (IDL) development in pure tantalum (Ta) and Ta-20 W alloy systems under collision cascadeevents. The investigation considered primary knock-on atom (PKA) energies ranging from 5 to 30 keV at 30 K andsubjected volumetric structures to six distinct strain values, encompassing both compressive and tensile strains. Our resultsrevealed that the number of surviving Frenkel pairs (FPs) and self-interstitial atom (SIA) clusters increased with tensilestrain and decreased with compressive strain, with the Ta-20 W alloy exhibiting the lowest observed numbers compared topure Ta. Notably, SIA clusters in pure Ta were approximately double those in alloyed structures for clusters containing twoto four atoms. We also observed that pure Ta systems displayed larger and longer IDL segments than alloyed Ta systems,which featured smaller and shorter IDLs. The applied strain was found to lower the barrier for IDL formation, potentiallyleading to material degradation. In conclusion, this study highlights the importance of considering the effects of strainand alloying in radiation-damaged environments, particularly in low-temperature, high-radiation-energy environments.
GIS-based sinkhole susceptibility mapping using the best worst method
Mohammad Maleki,Mohammad Salman,Saeideh Sahebi Vayghan,Szilard Szabo 대한공간정보학회 2023 Spatial Information Research Vol.31 No.5
Sinkholes are among karst forms and their formation is continuous and their identification is essential in several fields of life, such as water resources management, environmental hazards management, and tourism. This study aimed to identify the sinkholes and the sinkhole susceptibility in the Bistoon-Parav karst region, Iran. Ten sinkhole causative factors, precipitation, temperature, evaporation, lithology, soil type, slope, latitude, fault, stream and vegetation were involved in the sinkhole susceptibility model applying the best worst method, and we also determined the importance of the factors. The final sinkhole susceptibility map was produced by the weighted summing up the factors based on the variable importance. Lithology was the most important factor with 31.52% in the formation of sinkholes. The validation step was executed with a sinkhole database based on visual interpretation of high-resolution imagery. Finally, the receiver operating characteristic (ROC), completeness, correctness and quality index were applied to validate the performance of the sinkhole susceptibility map model. According to the validation parameters, the value of the ROC, completeness, correctness and quality was 81.90%, 100%, 59.41% and 59.41%, respectively. Thus, it can be said that the produced model shows acceptable performances for sinkhole susceptibility mapping. Also, this model showed that almost 7.4% of the region has the potential to become a sinkhole in the future.
Optimal architecture of heat generating pieces in a fin
Mohammad Reza Hajmohammadi,Sadegh Poozesh,S. Salman Nourazar,Ali Habibi Manesh 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.4
This paper documents the optimal architecture of heat generating pieces connected to and cooled in a circular-shaped fin. Relying on the constructal theory, the optimal distribution of multiple heat sources is obtained by minimizing the thermal resistance of the fin. Since the heat sources are contemplated as electronic devices with uniform heat generation, the minimization of the thermal resistance is indicated by minimization of the hot spot (peak) temperature. Temperature fields in the fin and in the heat sources are calculated using a finite elements approach of MATLAB PDE toolbox. Comparison among the considered configurations reveals that the regular configurations of the heat sources commonly used in cooling industry are not optimal and must be avoided. Optimal configurations such as triangular arrangement of heat sources are proposed to replace the unfavorable configurations.
Synthesis and Characterization of Chemiluminescent Conducting Polyluminol via Biocatalysis
Mohammad Reza Nabid,Soheil Salman Taheri,Roya Sedghi,Seyed Jamal Tabatabaei Rezaei 한국고분자학회 2011 Macromolecular Research Vol.19 No.3
The enzyme catalyzed polymerization of luminol (5-amino-2, 3-dihydroxy-1, 4-phthalazinedione) in the presence of polystyrenesulphonate (SPS) is introduced. Polymerization was achieved using horseradish peroxidase (HRP) as a biocatalyst in a phosphate buffer at pH 8. A green, water-soluble conducting PLUM/SPS complex was obtained. The physico-chemical properties of the product, including possible photoluminescence of the PLUM/SPS complex, were studied. The PLUM/SPS complex was shown to be a chemiluminescent (CL) material that is highly sensitive towards Fe^3+ ions. The quantum yield of the PLUM chemiluminescence was determined to be moderate (0.09 ± 0.01) compared to other chemiluminescent compounds. UV-visible, FTIR, ^1H NMR, GPC and conductivity measurements confirmed that the electroactive form of polyluminol (PLUM) was formed and complexed to the SPS.
Mohammad Reza Hajmohammadi,S. Salman Nourazar,A. Campo 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.5
This paper deals with the effects that a thin gas layer exerts on the hydrodynamic aspects of power law liquid in a radial Couette flowbetween two cylinders. Analytical solution is made to determine the velocity profile in the two-phase flow system occupied by the powerlaw liquid and the micro layer of a gas. It is shown that the thin (micro) gas layer contributes in reducing torque to set the fluid in motionin most cases. However, by considering generalized power law liquids, this paper limits the credibility for the positive role of the gaslayer on reducing the torque for lubrication. For instance, when n < 0.5 (n is the behavior index of the liquid), slight increment in thetorque (about 6%) is reported. Finally, energy gradient method is used for stability analysis. It is shown that the stability nature may bechanged based on behavior index of the liquid.