The aim of this study is an investigate the effect of design parameters and profile modification on static transmission error and load sharing factor of helical gears using analytical method with Matlab software. In the first step, we define the concept of transmission error that is the source of noise in the gear pair. Then load sharing factor and static transmission error are calculated using the gear mesh stiffness. In this paper the total stiffness of helical gear’s and the load sharing factor is determined using an accumulated integral potential energy method. In the next, results are verified and the effect of design parameters on avarege and pick to pick of the helical gears transmission error and load sharing factor is investigated. This parameter is called macro-geometric parameters of gear pairs. At the end, we write a Matlab code to modify the tip relif of tooth to optimize the load sharing factor and static transmission error. The results of this study show that the simultaneous correction of macro-geometric modifications and profile modification (micro-geometric modifications) cause a more uniform load distribution and significantly reduce the transmission error of the helical gear and consequently reduce the noise and vibration of the gearboxes.

Calculation of distribution coefficients is one of the essential provisions in the safety assessment of radioactive waste repository and safe management of radioactive waste. Due to the importance and characteristics of thorium radionuclide in radioactive waste inventory, the distribution coefficient of thorium in the alluvium soil of Anarak Radioactive Waste Repository was determined by the Batch method two parameters of thorium concentration and soil granulation were studied. Also, the Flow-Through method studied the adsorption behavior of thorium has investigated the effect of thorium concentration and soil height. The average value of thorium distribution coefficient in Anarak soil was calculated 110960 L/kg using the Batch method. The study of adsorption behavior by the Flow-Through method demonstrated high uptake of thorium in the soil due to the strong bond created between the ion and the adsorbent. The results showed that the distribution coefficient increases with the decrease of soil particle size. Regarding the effect of concentration on the thorium distribution coefficient, first, an increasing trend and a decreasing trend were observed in the test range. The results obtained in this study were compared with the results of other studies on thorium radionuclide, which showed a good agreement with other studies.

This study investigates the distribution coefficient of strontium in a soil sample in the south of Tehran. In this research, the columnar method  was used to determine the distribution coefficient of strontium. Also, the effect of three factors, pH, strontium concentration, and soil height in the column was studied using the RSM method's experimental design. For this purpose, five different levels were considered for each parameter, and the experiments were designed and performed by MiniTab software. According to the results obtained in the predicted model, pH, column height, interaction between pH and column height, the interaction between pH and strontium concentration, and interaction between strontium concentration and column height are important. The square of the coefficients as well as the concentration of strontium, did not have much effect on the distribution coefficient. The most significant effect is due to the height of the column, which increases with increasing the height of the column. The rate of conformity of the predictive equation with the actual values ​​is 96.39%, which is an acceptable value.

The safety assessment of Anarak site as the only center for the disposal of radioactive waste is of particular importance in order to maintain human health and the environment. Distribution coefficients of radioactive materials in the soils of the area under study is one of the influential parameters in the safety assessment calculations. Therefore, in this study, the distribution coefficient of cobalt in the alluvial soil of Anarak waste was determined by the batch method and two parameters of concentration and soil to solution ratio were studied. Linear adsorption isotherms, Friendlich and Langmuir were also analyzed to determine the adsorption behavior of cobalt in Anarak soil. The average value of cobalt distribution coefficient in the mentioned soil was calculated equal to 247.18 mL / g. The adsorption behavior of cobalt in Anarak soil followed the Langmuir adsorption isotherm with a positive and significant correlation. The maximum amount of cobalt uptake was determined as 0.029 mg / g soil. The results of the distribution coefficient obtained in this study are lower than the most of the values ​​presented in the other previous researches, which can be related to the soil texture (sandy loam) and the other soil characteristics.

In the present study, Valeric acid extraction in aqueous two-phase systems polyethylene glycol with a molecular weight of 4000 g / mol and sodium dihydrogen phosphate (NaH2PO4), di-potassium hydrogen phosphate (K2HPO4), and di-ammonium hydrogen phosphate ((NH4) 2HPO4) At temperatures of 35 and 25 degrees Celsius. The effect of salt type and its concentration, temperature, and pH on the formation of an aqueous two-phase system were studied. It was observed that with increasing salt concentration, the distribution coefficient and the percentage of extraction of Valeric acid decreased. The salt type has an important effect on the extraction of Valeric acid so that the sodium salt of dihydrogen phosphate has a higher distribution coefficient(%44) than the other two salts. Also, the extraction of Valeric acid in a lower temperature(Temperature is 25 ° C) environment resulted in a better result. In this study, pH values of 5,6,7,8 were investigated and it was observed that the distribution coefficient of Valric acid would be higher(pH = 5), and the maximum percentage of extraction of Valeric acid for the best salt (sodium dihydrogen phosphate) was obtained up to 50%.

Nowday, slab track is widely used in the world as railway supresturture because its advantages in comprison with conventioanl ballasted railway superstureure. So, design and analysis process of railway slab track is one the main issues in recent researches.  One of the main factor in the design and analysis of slab track is distrubtion of vertical load on longitudinal direction of the track (load distribution factor). In this paper, a 2D numerical model is developed in FORTRAN to investigate the effect of slab track properties on the load distribution factor. In this model, the slab track is comprised of rail, fastening system, concrete slab, elastic layer, concrete base and subgrade. Rail, concrete slab and concrete base are modeled as two nodeded beam element and fastening system, elastic layer and subgrade are simulated as spring element. According to the elements stiffness matrices, slab track stiffness matrix is developed. A wheel load is applied on the rail (in the middle of the model). Based on the two noded beam element shape functions, load vector of the model is developed. The equlibrium equation of the model is solved and load distribution factor is derived. To investigate the validity of the results obtained from the model, a comparsion is made between results obtained from the model and those of ABAQUS as a commercial finite element software. Rail displacement, concrete slab displacement, concrete base displacement and load disribution factor obtained from the ABAQUS are compared with those of the model developed in this paper and a very good agreement was illustrated between results. A parametric study was performed to investigate the effects of rail flexural rigidity, fastening system stiffness, concrete slab flexural rigidity, elastic layer stiffness, concrete base flexural rigidity and subgrade stiffness on the load distribtion factor. The results obtaine from the parametric study indicate that as the slab track element stiffness or flexural rigidity is decreased, the load distribution factor is decreased and vertical load is distributed widely in the longitudinal direction of the track. Rail pad stiffness has the maximum effect on the load distribution factor reletive to the other parameters. As the rail pad stiffness is changed from lowest to highest magnitude, the load distribution factor is varied from 0.3 to 0.7. The results obtained in this research indicate that propeties of lower slab track elements have lower effects on the load distribution factor compared to the upper slab track elements. So when the flexural rigidity of the concrete slab is changed from low to high, load distribution factor is changed from 0.52 to 0.54. Moreover, when the elastic layer stiffness, concrete base flexural rigidity and subgrade stiffness are changed from low to high, the load distibution factor are almost unchanged and is roughly 0.54. This shows that elastic layer stiffness, concrete base flexural rigidity and subgrade stiffness do not have any significant effects on the load distribution factor. So when a model is developed to calculate the load distribution factor and dcrease of analysis computation cost, elastic layer stiffness, concrete base flexural rigidity and subgrade stiffness could be ignored in the model.

This research focused on zircon/rock partition coefficients of REEs in the acidic rocks of the Dar Gaz district, located in the southeast of the Kerman Province, in order to determination of oxygen fugacities and zircon crystallization temperatures. Zircon/rock partition coefficients were determined in three different types of acidic rocks including plagiogranite intrusions, plagiogranitic dikes and granitic dikes (two samples from each rock type) in the Dar Gaz district. Partition coefficient results determined based on the composition of the host granitoids and the zircon grain composition indicate that the patterns of the trace elements in zircon grains are controlled by the liquid composition at the moment of crystallization and are magmatic type. Zircon/rock partition coefficients indicate LREE depletion and HREE enrichments consistent with host rocks and magmatic zircons. Ti-in-zircon temperatures range from 707 to 1046 ºC. Zircon crystallization temperature, oxygen fugacity and Ce4+/Ce3+ ratios decrease from plagiogranite intrusions toward plagiogranitic dikes indicate that plagiogranite intrusions formed by hydrous partial melting of gabbro cumulates. The plagiogranite dikes formed by more fractionation of this felsic melt. Finally granitic dikes are probably formed by fractionation of a felsic melt produced by partial melting of sedimentary material.

In this study, for aerodynamic analysis the vertical axis of Darius H type of hydrofoil micro water turbine, three hydrofoil NACA0015, NACA0018 and NACA0021 were selected and modeled using the Bezier equation of hydrofoil using its original model. Then, using the HOPMBL coding method, which was solved by the boundary element method, the NACA0015 hydrofoil pressure distribution coefficient was better than the other two hydrofoils numbers in different Reynolds numbers, and in another method, the maximum lift to drag coefficient using Q-Blade NACA0015 hydrofoil software The drip lift is higher on the Reynolds 53670 than on any other hydrofoil, at 5.9degree angle of 24.3, which is why the NACA0015 was chosen. Then, to analyze the hydrofoil of the fluent software, it used the KW-SST model to obtain the lift coefficient, drag coefficient and the pressure distribution coefficient in terms of length, and compared it with the data obtained from the Q-Blade software. Next, the water micro turbine with NACA0015 hydrofoil with chord length, blade height and rotor radius of 6.4, 35 and 18.5 cm was designed in catia software and manufactured. Then, the hydro-turbine designed in Ansys Fluent software was simulated with Realizable k-e model and analyzed velocity and pressure static conditions.

In this study, computational fluid dynamics simulation of liquid-liquid extraction of zinc was performed using trifluoroacetylacetone as a solvent in the hollow fiber membrane contactor. Mass and momentum balance equations (Navier-Stokes) were used to express the transport of zinc solutes through the membrane contactor. After applying the conditions, the governing equations were simulated using the finite element method. After validating the results, simulation was performed to study the distribution of zinc concentration in two-dimensional and three-dimensional form, as well as to investigate the effect of different parameters such as distribution coefficient and current intensity on the extraction efficiency. The results showed that by increasing the partition coefficient from 1 to 10, the amount of single-pass extraction increased from 10 to 100 percent. Also, the extraction efficiency in the counter-current flow of pipe and shell is 9% higher than in the co-current flow. Furthermore, this study showed that computational fluid dynamics could be used as an effective tool for the development of membrane-based extraction processes.

For hydrazine producing with concentration more than 64 wt%, remaining amount of water in hydrazine Hydrate, could not be removed easily to produce hydrazine with concentration more than 64wt%. In this work, Butanol, an aliphatic alcohol with four carbone atoms, was used as a solvent in liquid - liquid extraction of hydrazine. The binodal curve and the experimental tie lines for the ternary {water (1) – hydrazine (2) – butanol (3)} system were determined by cloud point method using the refractive index criteria at the temperatures of 15.2, 25.2 and 40.2 C, in atmospheric pressure. The distribution coefficient of Hydrazine (D) and its separation factor (S) were determined equal to 0.0425-0.3628 and 0.2768- 1.5179, in the usage concentration and temperature ranges, respectively. Afterword the experimental tie lines were correlated by the Non-Random Two-liquid model (NRTL) and the Universal Quasi Chemical model (UNIQUAC) with Root Mean Square Deviation (RMSD) equal to 0.0227 and 0.0495, respectively. In addition, the sodium hydroxide addition effect was studied on equilibrium behaviour of the system at 25.2 C. Addition of 10 wt% NaOH causes an increase of 13.16 % in the average distribution coefficient of hydrazine as well as 96.26% in the average separation factor.