Carbon dioxide is one of the most important greenhouse gases that plays a major role in global warming. Gas hydrates are one of the newest technologies available to remove this gas before entering the atmosphere. In this research, the effect of the stirrer speed on the most important kinetic parameters of carbon dioxide hydrate formation, i.e. amount of gas uptake, hydrate growth rate, storage capacity, and water to hydrate conversion percentage in a constant-volume constant-temperature reactor was investigated. The experiments were carried out in the presence of double distilled water at a temperature of 278.15 K and two pressures of 2.9 MPa. Vertical and horizontal stagnant conditions and rocking cell stirrer with speeds of 2, 4 and 10 rpm were used to investigate the effect of stirrer speed on the kinetics of carbon dioxide hydrate formation. The results of the experiments showed that the use of a stirrer promotes the kinetics of carbon dioxide hydrate formation. The use of a stirrer at a speed of 10 rpm increased the amount of gas uptake compared to the vertical and horizontal conditions, respectively, by 84.4 and 78.5 percent. The storage capacity of carbon dioxide hydrate formation increased by 72.6% and 67.7%, respectively, when using a stirrer at a speed of 10 rpm compared to the vertical and horizontal conditions.

Air pollutants from iron and steel making operations have historically been an environmental concern. The factory located at Ahwaz, Iran, has two production lines namely, 630 and 650, which produce iron parallel edge. The objective of the study is to determine indoor respiratory particulate matter (RPM) and FeO concentrations and their comparison with NIOSH standards. This is a cross–sectional study of personnel working in different environmental conditions. There were significant differences in mean concentrations of RPM (P<0.05) in line 650 but not in line 630 as compared to NOISH standard (3 mg/m3). The FeO concentrations in line 630 and 650 are significantly lower than the NIOSH standard (5 mg/m3). There is maximum FeO concentration in station 7 (0.8 mg/ m3), due to remains of iron on the billets. In other words, after cutting the beam by saws, carried out with water pressure of 150 Bar and immersing in cooling beds, the temperature decreases from 550oC to 150oC. As the result, airborne iron oxide concentrations decrease in the respiratory air zone of workers. There is maximum RPM concentration in station of Billet rejecter for line 630 (7.645 mg/m3), because this station carries out peel action on metal. The primary form of RPM is not directly related to the iron handling but may be related to improper ventilation and exhaust system.  

Background: Aim of this study is to evaluate the accuracy of the gated volumetric modulated arc therapy (VMAT/RapidArc) using 2D planar dosimetry, DynaLog files and COMPASS 3D dosimetry system.Materials and Methods: Pre-treatment quality assurance of 10 gated VMAT plans was verified using 2D array and COMPASS 3D dosimetry system. Advantage of COMPASS over 2D planar is that it provides the clinical consequence of error in treatment delivery. Measurements were performed for non-gated and different phase ga.ng window level (80%, 50%, 30% & 20%) to know the impact of ga.ng in VMAT dose delivery.Results: In 2D planar dosimetry, gamma agreement index (GAI) for all measurements were more than 95%.DynaLog file analysis shows the average devia.ons between actual and expected posi.ons of monitor units, gantry and mul.-leaf collimator. The STDVs MU and gantry posi.on were less than 0.10 MU and 0.33o respec.vely.Root mean square (RMS) of the devia.ons of all leaves were less than 0.58 mm. The results from COMPASS show that 3D dose volume parameters for ten pa.ents measured for different phase ga.ng window level were within the tolerance level of ±5%. Average 3D gamma of PTV and OAR’s for different window level was less than 0.6.Conclusion: The results from this study show that gated VMAT delivery provided dose distribu.ons equivalent to non-gated delivery to within clinically acceptable limits and COMPASS along with MatrixEvolution can be effec.vely used for pretreatment verifica.on of gated VMAT plans.

Wettability alteration has been a sophisticated issue for scientists and reservoir engineers since early 20th century; thus, many investigations have been carried out to determine wettability and enhance it to ideal conditions, which leads to improvement in oil recovery. Dilute surfactant flooding has been ap-proved as one of the noteworthy methods in chemical flooding. Several petroleum reservoirs were rec-ognized as suitable nominees for surfactant/water flooding when screening criteria were established. Surfactant flooding was applied to mobilize the trapped oil in reservoirs. The key mechanism to enhance oil recovery by surfactant flooding was defined as rock wettability alteration. Experimental investigations into the impact of aging and temperature on wettability alteration were performed. Subsequently, core flooding test of surfactant was performed to define the effect of thinned cationic surfactant slug with cyclic 7 days technique (Multi-slug injection) on displacement sweep efficiency in the carbonate core of Bangestan reservoir with its heavy oil reservoir. Moreover, contact angle and interfacial tension (IFT) measurements were made to gain the supplementary information for a surfactant/water flooding. The best concentration of C19TAB was determined by measuring interfacial tension values of the crude oil in contact with surfactant solutions prepared in synthetic brackish water. Results displayed a decrease in residual oil saturation by changing the contact angle and IFT reduction between oil and water. Moreover, aging was known as a significant constraint to change the wettability index to make similar oil-wet condition. Besides, laboratory experiments verified that the influence of wettability alteration was higher than IFT reduction.

In the current research project, the thermal performance of a series of newly designed mixers has been investigated. Each mixer has two concentric cylinders comprising two annular slot flow channels around a solid cylindrical rod at the center. In each mixer, the first cylinder around the central solid rod has either spherical or pyramidal protrusions throughout the outer surface. It has been observed that with varying mass flow rate of cold and hot water (1 kg/m3-sec to 5 kg/m3-sec), 17% increase in rate of heat transfer for cold water & 73% for hot water has been observed with a variation in mass flow rate of 1-3 kg/m3-sec with all combination of angles of holes in spherical protrusions. In the case of pyramidal protrusions, the rate of heat transfer has been raised from 16% for cold water & 88% for hot water at varying a mass flow rate of 1-3 kg/m3-sec in all combinations of angles of the top vortex in each protrusion. The effect of imparting the centrifugal force has raised the rates of heat transfer in the range of 24-36% at varying rpm from 60-180 rpm of the central cylinder, with the highest with 120 rpm. A comparison of the heat transfer rates reveals that with increasing the mass flow rates, rpm, angle of the holes in spherical protrusions and angle of the traversed angle at the top corner of each pyramidal protrusion didn’ t contribute linearly in terms of rising in the rate of heat transfer.

Diesel engines are used in sensitive military and industrial applications as stationary power sources. In order to stabilize voltage and frequency of connected generator, diesel engine RPM would be controlled accurately. In most cases mechanical methods are used to fix the engine RPM but this method is not very accurate. In this paper a new electronic governor has been designed and constructed with programmable logic controllers (PLC). The designed controller is cheaper, more flexible and more accurate than mechanical governor. It has initially been simulated in MATLAB Simulink which showed adequate results. It was then constructed and installed on a 350 KW diesel generator in which 3. 2% improvement over conventional methods was observed.