فهرست مطالب hamid reza ghomi

In this paper, zirconium carbide (ZrC) thin films were deposited on glass and aluminum substrates using DC magnetron sputtering. It was found that different ratios of acetylene gas (C2H2, as a reactive gas) in the gas mixture of acetylene and argon (Ar, as a sputtering gas) affect the microstructural properties, corrosion behavior, and protection efficiency of ZrC thin films. X-ray diffraction (XRD) was used to characterize the microstructural properties of thin films. The corrosion behavior of thin films in a 3.5% NaCl solution was evaluated by potentiodynamic polarization tests and electrochemical impedance spectroscopy (EIS). FESEM was also employed to examine thin films' surface morphology and thickness.

In this study, a new method for measuring the velocity of plasma bullets, based on receiving and detecting the electrical signal of the bullets using an array of cascading antennas in an argon plasma jet with a tip-ring structure is presented. In this structure, the tip electrode plays the role of igniter of plasma generation and the ring electrode plays the role of controlling the plasma jet. To study the variations in the plasma jet, the ring electrode was located at different distances from the tip electrode and the variations in the velocity of the bullets were measured. The experiments showed that if the two electrodes were 1.5 cm apart, at a distance of 15 cm from the plasma formation site, the velocity of the bullets would be about 140 km/s. If the two electrodes are 3.25 cm apart, the bullets will have a speed of about 120 km/s, and if the two electrodes are 5 cm apart, the bullets will have a speed of about 100 km/s. Examination of the results showed that by increasing the distance between the two electrodes, the velocity of plasma bullets also decreases significantly. The results also showed that by moving away from the plasma formation site in the jet tube, the average velocity of plasma bullets increases. For example, at a distance of 21 cm from it, the average speed of plasma bullets in all three configurations will be about 120 km/s. Finally, by varying the electrical power, we concluded that as the electrical power increases, the speed of the bullets increases. According to the obtained results, by doubling the applied power, it was observed that at a distance of 15 cm from the place of plasma formation, the velocity of the bullets will be about 40 km/s at lower power and about 90 km/s at higher power; These results are obtained if the distance between the two electrodes is 3.25 cm and the initial electrical power is 20 Watts.

In this research, the effect of cold plasma treatment on the germination characteristics of Camelina sativa, Kelussia odoratissima, and Heracleum persicum seeds were investigated. An experiment based on completely randomized design with in three replications was conducted. The treatments were three cold plasma power of 40, 60 and 80 W applied on the seeds for 2 minutes and untreated sample was also evaluated as control treatment. The measured traits were: germination percentage and rate, plumule and radicle length. The results showed that cold plasma treatment had a significant effect on germination percentage, germination rate, and radicle length. The cold plasma at 80 kV and 2 minutes improved the germination percentage with increasing it by 10.6%, increasing germination rate by 2.35%, and 3.6 centimeters in radicle length in compared with the control sample. Based on the results obtained from K. odoratissima and H. persicum seeds, cold plasma couldn’t break the dormancy of these seeds, despite the improved hydrophilicity and disinfection of the seeds.

In this study, the drying kinetics of saffron stigmas pretreated by atmospheric pressure cold plasma pretreatment (15, 30, 45 and 60 s) followed by hot air drying (60°C and 1.5 m/s) were modeled using 10 conventional mathematical thin layer models. The use of cold plasma pretreatment reduced drying time and enhanced effective moisture diffusivity (Deff). The most accurate models describing behavior of drying process of stigmas were Two-term, Midilli and Kucuk and Wang–Singh models. These models were determined based on the higher value of coefficient of determination (R2) and the lower values of root mean square error (RMSE), chi-square (χ2) and sum of square errors (SSE). In addition, the Newton model did not in accordance with experimental data.  The value of Deff of pre-treated saffron stigmas were in the range of 8.7013×10-9 and 9.1139 ×10-9 m2/s depending on the time of pretreatment. The use of cold plasma pretreatment reduced the surface resistance to moisture transfer, improved the diffusion coefficient, and subsequently, reduced the drying time.

Higher military education centers play a prominent strategic role in developing professional capabilities of Iranian society and consequently examining the performance of these centers have a wider significance for all mangers. This study was an attempt to measure the research performance of the Iranian state university through utilizing analytic hierarchy process and network data envelopment analysis. For this purpose, authentic research indicators were identified and selected through investigating related literature review and also interviewing with elites. Thereupon, in an attempt to weigh the indicators and also combine the research indicators with macro indicators, analytic hierarchy process was run in this study. Moreover, the research involves collecting data from university macro-indicators; the collected data were assessed and analyzed through running network data envelopment analysis. This study is an applied, descriptive and also qualitative in terms of purpose and data collection procedures and analysis. The findings of the research inputs and outputs revealed that there is a lack of relative research efficiency at two colleges of this university.