During mold filling, molten metal can only advance as quickly as the AIR inside the cavity is expelled. In this work an analytical model describing AIR flow is developed based on a incompressible flow theory. AIR PRESSURE has serious effects upon the filling behaviour such as surface profile and filling time. In this work a new mathematical model is proposed for calculation the AIR PRESSURE during the mold filling. A single phase computational fluid dynamic code based on the SOLA-VOF algorithm used for prediction the fluid flow. AIR discharged through the vents is modelled by ideal gas assumption, conservation of mass equation and Bernoulli law. A new algorithm was developed to interpolates the AIR PRESSURE on the surface cell. The creation of AIR back PRESSURE was correlated with sizes of vents and pouring basin height. In order to verify the computational results a series of experimental test was conducted. Comparison between the experimental data and simulation results has shown a good agreement.

PRESSURE swing adsorption is an important unit for gas separation and purification. In order to develop the PSA technology, a pilot plant including four beds each with 1 meter length and 3.5 cm ID was designed and built. This pilot includes control systems and analysis systems to investigate the various operational conditions of beds carefully. In order to test this pilot, separation of oxygen from AIR, using zeolite 5A type adsorbents’, was studied. In this process the steps of feed pressurization, production, blow down, purge, PRESSURE equalization (two steps) and product pressurization are included in a cycle. The effects of PRESSURE, cycle time, flow rate of feed and purge on gas purity and recovery were studied. Also modeling and simulation of this process was done by orthogonal collocation method and MATLAB software. The numerical results obtained from modeling were compared to the experimental results and gave reasonable agreements.

An 1D hydrodynamic model has been simulation and developed for gas hold-up and liquid circulation velocity prediction in AIR-lift reactors. model is based on momentum balance equations and has been adjusted to experimental data collected on a pilot plant reactor equipped with two types of gas distributors and using water as the liquid phase.The model equations described previously constitute a set of non-linear equations which are solved by an iterative procedure (v.b) (c plus). This model has also been combined with mass transfer and the kinetics of a chemical reaction to yield a complete model of the performance of a reactor.

AIR pads are vastly applicable in ultra precision machines. Spindle and table are the two main components of these machines which get advantages of such systems. The performance and efficiency of AIR pads have big influence on the whole machine quality. Parameters affecting PRESSURE distribution of AIR tables may be considered as, 1) AIR compressing method, 2) AIR nozzle diameter, shape, and size, 3) number of AIR pads, and 4) AIR gap thickness. In this study, effects of AIR pad shape on PRESSURE distribution in AIR gap have been investigated using ANSYS. In this simulation, FOTRAN environment have been employed. Investigated shapes for AIR pads are triangle, rectangle, pentagon, hexagon, ellipse and circle. PRESSURE distribution-distance from orifice have been plotted for each AIR pad shape. The results indicate that the rectangle AIR pad has the best PRESSURE distribution.

To examine hydraulics of LNAPLs in soil, the retention curves of diesel fuel and water were both determined by hanging column method. The soil retention parameters were obtained based on van Genuchten, Brooks-Corey and Campbell’s models. In addition, the soil hydraulic conductivity for both fluids were predicted based on Mualem- Brooks-Corey, Burdine- Brooks-Corey, Mualem-van Genuchten and Campbell’s functions. The results indicated the magnitudes of the pore-size distribution parameters remained mostly unchanged and the bubbling PRESSURE parameters were increased in diesel fuel-AIR compares to water-AIR system. The LNAPL was retained less than water owing to its negligible surface tension, yielding less needed tension to drain diesel fuel out from soils. In addition, the LNAPL retention curve was appropriately scaled based on the recommended scale factor. Due to high kinematic viscosity of diesel fuel and low soil retention for diesel fuel, the saturated and unsaturated soil hydraulic conductivity of diesel fuel was less than that of water.

Experimental and numerical investigation of multihole gasoline direct injection (GDI) sprays at high injection PRESSURE and temperature are performed. The primary objective of this study is to analyse the role of gas entrainment and spray plume interactions on the global spray parameters like spray tip penetration, spray angles and atomization. Three-hole 90° spray cone angle and six-hole 60° spray cone angle injectors are used for current work to examine the effect of the geometry of the injector on the spray interactions. The numerical results from Reynolds Average Navier Stokes (RANS) simulations show a reasonable comparison to experiments. The simulations provide further insight to the gas entrainment process highlights the fact that a stagnation plane is formed inside the spray cone which basically governs the semi collapse of spray that in turn affects the spray direction and cone angle.

Pressurized pipeline systems may have a wide operating regime. This paper presents the experimental analysis of the transient flow in a horizontal pipe containing an AIR pocket, which allows the ventilation of the AIR after the pressurization of the hydraulic system, through an orifice placed at the downstream end. The measurements are made on a laboratory set-up, for different supply PRESSUREs and various geometries of water column length, AIR pocket and expulsion orifice diameter. Dimensional analysis is carried out in order to determine a relation between the parameters influencing the maximum PRESSURE value. A two equations model is obtained and a criterion is established for their use. The equations are validated with experimental data from the present laboratory set-up and with other data available in the literature. The results presented as nondimensional quantities variations show a good agreement with the previous experimental and analytical researches.

Tehran is one of the polluted cities in the world. Despite the effective acts of the city authorities there is not yet sign of improvement. Because the main factor, that is, the PRESSURE distribution is not considered. This research is undertaken to analyze the relation between the PRESSURE changes and the pollution concentration of Tehran and identify the effective PRESSURE patterns.  For this purpose the polluted days of Tehran according to CO, NO2, SO2, and TSP were extracted from the daily pollution data of Villa station, located in the central part of Tehran, during 1984-2001 period. The NCEP 00 GMT daily PRESSURE data of the pollution days at 2.5 degrees apart grid points within the 20°N to 47.5°N and 35°E to 67.5°E window were used.        Through the use of Principal Component Analysis and Clustering methods the PRESSURE distribution of pollution days were classified into six groups and then the composite PRESSURE pattern of each group was mapped. Each composite map was assigned as a weather type. These weather types are as: Northwestern Anticyclone, Caspian Low, Siberian Anticyclone, Western Anticyclone, Khorasan Low, and the Zonal type. Most of the types were frequent in fall. The Khorasan Low is the dominant type during the short period pollution runs whereas the Zonal type is dominant during longer pollution episodes.     The relation between the PRESSURE changes and the pollution concentrations were studied through the use of the daily PRESSURE of the Mehrabad station and pollution values of Villa station. The results showed positive relation between the Mehrabad grid point PRESSURE and pollution concentration of  CO, NO2, and  SO2, but negative relation with the concentration of TSP.

The influence of sodium dodecyl sulfate and Triton X-100 surfactants on the two-phase PRESSURE drop and two phase flow regime of water-AIR and gas condensate-AIR in upward vertical pipe were investigated for various gas/liquid flow rates. Sodium dodecyl sulfate and Triton X-100 reduced the PRESSURE drop of single phase water flow by 11% and 29% compared to that of pure water single phase flow at water velocity of 13 m s-1. For condensate single phase flow, sodium dodecyl sulfate and Triton X-100 reduced the PRESSURE drop by 9% and 17% compared with that of condensate single phase flow with no surfactant at gas condensate velocity of 13 m s-1. The maximum efficiency of sodium dodecyl sulfate and Triton X-100 in reducing the PRESSURE drop of water-AIR system were 67. 1% and 79. 8%, respectively, compared to that of pure water-AIR two-phase flow. For gas condensate-AIR system, the maximum efficiency of sodium dodecyl sulfate and Triton X-100 in reducing the PRESSURE drop was 57. 1% and 36. 7%, respectively, compared to that of pure condensateAIR two-phase flow.

In this study, AIR density and water vapor PRESSURE for 184 synoptic meteorological stations in the year2004, 2005 and 2015 were calculated based on the theoretical of computing these two parameters. The results indicate monthly, seasonal and annual averages of WVP and AIR density were maximum values over shores of the Caspian-Sea and the Persian-Gulf, while the values were minimum over the highlands of the Zagros and Alborz mountains. These results are compatible with theoretical fundamentals indicating the exponential reduction of density with height. Moreover, it was observed that the monthly, seasonal and annual averages of AIR density over shores of the Caspian-Sea were higher than the corresponding values over the Persian-Gulf coasts. These conditions occur due to changes in AIR PRESSURE as a result of cold high PRESSURE system extension in the cool season where its related dominating ridge affects most regions of Iran causing AIR PRESSURE increase over the Southern-Caspian-Sea(SCS) proportional to the corresponding value over Iran’ s-Southern-Coasts(ISC); hence the average density during winter season over the SCS where affected by high PRESSURE systems is more than corresponding value over the ISC. During the warm seasons a result of heat low PRESSURE system predomination over southern Iran, AIR PRESSURE decrease over these regions, while the SCS area are subjected to relatively high PRESSURE system. Therefore AIR density average over the ISC will be lower than the corresponding one over the SCS in the warm season.