The Float method is a quick approximation technique for measuring velocity and thus flow rate. Surface velocity obtained by the Float method of Correction factor is multiplied by the average velocity in the cross section obtained. This coefficient by the The United States Bureau of Reclamation (USBR) to measure the Float method is presented. Surface velocity coefficients published by USBR are based solely on average water depth. But other hydraulic factors such as longitudinal bed slope, the wall roughness height, the shape of the channel cross section, the location of the float object and... may also affect the value of the coefficient. In this study the effect of these parameters on the surface velocity coefficient in a rectangular and compound open channel studied and the results are compared with the coefficients published by USBR. The results indicate that these parameters are the effective surface velocity coefficient and considering effect of other parameters in addition to the average water depth, be accuracy of the float method could significantly increase.

This paper investigates the heat transfers and ablation of thermal insulators used in motors and nozzles. The heat and mass transfer equations are considered in two dimensions in a convergent-divergent nozzle. The finite volume method and the implicit method for time dependence have been used to solve these equations. We used the equations finite volume method with implicit formulation for time dependency to solve equations. The reaction equation, which is written in the form of Arrhenius, is solved using the Runge-Kutta method, and the density and the flux of the gas produced at each step are obtained. Also, we represent a model for the rate of recession. The validation of the model is compared with the experimental results in silica-phenolic ablation insulators and shows a good agreement of the simulation results with the experimental observations. After validation of the obtained results. The effect of the blowing Correction coefficient has been investigated, the results show that this coefficient is very important for the accurate design of ablation insulators. The blowing Correction factor reduces the convection heat transfer coefficient, reduces the surface recession, and thus, reduces the back temperature of the insulation. Therefore, in cases where the thickness of the insulation is significant or the heat of ablation is low. This parameter can be important and affect the final results and thus the final design.

Therefore, in order to solve the flood damage and flooding problems, as well as adopting appropriate guidance methods to use of urban runoff and implementation of the correct water principles in urban watershed management, first, it is necessary to adopt appropriate methods to study the rain water cycle and the production runoff volum of precipitation events in urban areas. It should be noted that the rain water cycle in urban areas in this research was investigated using the water balance formula in district 9 of Mashhad city. Results showed that the delineation of watershed border is the first important issue in the hydrologic modeling of urban catchments which plays an important role in determing the total runoff volume generated from hydrologic homogeneous units. The results showed that runoff volume of buildings Homogeneous units is more than streets and more than green spaces. The runoff volume values of hydrological water balance methods both were estimated to be almost identical. Finally, the Correction runoff coefficient was estimated for hydrologic homogeneous areas. results showed that the Correction runoff coefficient for the residential buildings homogeneous areas was estamied 80 of perecent. And for street homogeneous areas was estamied 78 of perecent and for homogeneous areas of the park and green space using the hydrological balance method Obtained 0. 048 of perecent.

Investigation of earth channel seepage is always taken into account by researchers due to water losses, reduction of soil quality around the channel and for canal lining issues. In this Present research a computer model has written in with seepage amount in an earth channel with natural cross section is calculated by solving general equation of water movement into isotropic or anisotropic soil under saturation condition by numerical finite volume method. Location of pheriatic seepage line using deformed mesh with tray and error is determined. Also amount of seepage is determined by means of Darsy relation and using of calculate head in boundary junctions. Evaluation of model accuracy viewpoint programming, seepage discharge and location of pharisaic seepage line calculated for a circular channel compared with results of analytical conformal mapping method. The results showed location of pheriatic seepage line and wide of seepage area overlaps in tow methods. Also difference between calculate seepage discharge by tow mentioned method decreases with increasing distant of ground water surface table from channel bed. Additionally to model verification two earth channel named Lolham and Shikhsarmast in Nazloo area of Uromiye province were selected and seepage discharge was determined by site measurement. Also the result of falling head hydraulic conductivity test showed hydraulic conductivity of bed material of Lolham and Shikhsarmast channels are 3.5 and 1.77 meter per day, respectively. Then cross section coordinate points and hydraulic conductivity as the only input data entered to model and amount of seepage has calculated that has less than 5% difference with measurement values. After model verification, constant coefficient of empirical relation for seepage calculation has modified using result of model running.

Objective: Ever since the World Health Organization formally identified the corona virus as a worldwide epidemic, various countries have entered new and, of course, unknown stages. The prevalence of the corona virus, in addition to posing serious health risks and problems, has had significant and sometimes irreversible effects on global trade and the economy. From there Iran is no exception to the prevalence of coronary disease in other countries and is facing a major crisis of this disease, the need to study and analyze the long-term causality between the prevalence and recurrence of persistent peaks of the disease and the country's economy is very important. Therefore, the purpose of this study is to analyze the long run causality between coronavirus prevalence as a dummy variable and selected economic variables (exports, transportation, unemployment and economic growth) in Iran. Methods: the Vector Error Correction Model (VECM) will be used and by estimating the coefficient of Error Correction Term (ECT) this issue will be investigated during the period 1978-2021. Results: Based on the statistical significance of the error Correction term coefficient, it can be concluded that in the model, except for exports and unemployment, other variables (transportation, economic growth, prevalence of Covid-19) cannot try to adjust the short run error to the long run equilibrium and cause to long run equilibrium in the system. Because the error Correction term coefficient only for exports and unemployment in this model is statistically negative and significant. Therefore, there is only causal relationship of other variables to exports and unemployment. According to the results of diagnostic tests, it was found that since the probability statistic in all tests is more than 0. 05, therefore, the null hypotheses of the tests are not rejected. Conclusion: Relying on the concept that the significance of long run dynamic relationships in the model is based on the statistical significance of the coefficient of error Correction term, it can be concluded that, except export and unemployment, other variables in the model (transportation, economic growth, prevalence of Covid-19) They cannot try to adjust the short run error to long run equilibrium and cause long run equilibrium in the system. Economic studies conducted so far during the epidemic show that the prevalence of coronavirus in economic sectors including tourism, foreign trade, capital markets, foreign exchange markets, housing markets, small businesses, public businesses, commodity prices, GDP will affect the interior. Due to the losses caused by the prevalence of coronavirus in the Iran's economy, if no immediate action is taken to compensate for the economic losses and a practical solution is not taken, the damage will increase exponentially and many economic activists will face many challenges which may even be removed from the economic cycle. Adapting countries to compliance with health protocols improves trade and exports. The government should put the safety of transport workers on the agenda to continue to provide essential services, and it is useful to apply the lessons learned from the experiences of areas that were affected by the disease early on.

Introduction and ObjectiveAwareness of the pattern of spatial and temporal variations of the rainfall erosivity is essential for improving soil erosion estimates, especially considering snow cover in different months. In the Caspian Sea Basin, due to the low distance between mountain regions and rainy plain, estimation of rainfall erosivity factor without considering snow cover Correction coefficients is associated with a significant uncertainty. Accordingly, the current study aims to analyze the spatiotemporal variations of the rainfall erosivity factor with considering snow cover Correction coefficient in the Iranian part of the Caspian Sea Basin.Materials and Methods To prepare monthly, seasonal and annual rainfall erosivity factor, monthly rainfall data of 56 synoptic stations of the Caspian Sea Basin were obtained from the national meteorological organization and statistical yearbooks with a common statistical period of 20-25 years (1996-2020). As a result, the rain erosive layer in different time bases using Co-Kriging geostatistical method with auxiliary variable of height above sea level with less root mean square error (RMSE) was used as the most common evaluation index and selection of the optimal method. Then the monthly snow cover layer was prepared from MOD10CM product and the rainfall erosivity for each month was modified.Results and Discussion Based on the results, the average annual rainfall erosivity factor of the Iranian part of the Caspian Sea Basin was 254.61 (MJ mm ha-1 hr-1), while by considering the snow cover Correction coefficient, the rainfall erosivity value was redused to 210.53 (MJ mm ha-1 hr-1). Also, Bandar Anzali and Manjil synoptic stations have the highest and lowest values of the average annual rainfall erosivity factor equal to 749.30 and 162.87 (MJ mm ha-1 hr-1), respectively. In addition, after considering the snow cover Correction coefficient, the highest monthly rainfall erosivity values of 27.27, 25.81 and, 25.56 MJ mm ha-1 hr-1 were observed in April, October and, November, respectively. On the other hand, 12.81% of the studied area is in the medium to very high levels of rainfall erosivity in the northern part of the Caspian Sea Basin, which can be used to prioritize different areas in order to carry out conservation measures to reduce the effect of the rainfall erosivity factor on the amount of soil erosion and sediment yield were used.Conclusion and Suggestions  Based on the results of the current research, it can be stated that the fluctuation of rainfall erosivity in different months and seasons is also affected by the rainfall time distribution throughout the year. Therefore, the maximum amounts of rainfall erosivity in most of the studied areas correspond to the main times of agricultural activities, i.e. planting and harvesting, which are critical times for soil erosion. Investigating the spatial pattern of rainfall erosivity in the Iranian part of the Caspian Sea Basin shows many relative changes between different regions from the plains to the highlands. Although this pattern is somewhat consistent with the pattern of climate changes from drier and less rainy areas to wetter and morerainy areas, the type of precipitation and especially snow in high areas has reduced the rainfall erosivity in these areas. Therefore, the temporal evaluation of rainfall erosivity resulting from the current research, in which the snow cover Correction coefficient is applied, with the timing of the presence and density of vegetation on the soil surface, provides more reliable results for land management managers and planners, especially in the agricultural sector, to choose the right type of crops for each will place the area.

Investigation in to the sediment delivery of watersheds and its variation is an important element of ecosystem management. Since sediment load depends on runoff quantity, and runoff is considered as a unique indicator of sediment load, in this research the two modified versions of the MUSLE model were evaluated for 9 torrential events in two sub watersheds of the Kamal Saleh watershed in the Markazi Province of Iran. To this end, first all factors of the model including runoff, erodibility, topographic, cover management, and support practice were estimated using routine equations of the model. Then, the power coefficient in the runoff factor was corrected, applying two methods: “m Correction coefficient” and “average Correction coefficient. The evaluation criteria showed that the “m Correction coefficient method” (compared to the “average Correction coefficient method”) reduces the difference of the observed and estimated sediment load of small and large torrential events remarkably. In fact, the application of this modified method increased the accuracy of the MUSLE by decreasing the standard deviation of prediction. Also, the validation analysis of the modified method showed that the coefficient of efficiency indexes for the Hasan-Abad station (Rudkhane Bozorg subwatershed) and Ghal' e-No station (Ashur-abad subwateshed) were 0.997 and 0.811, respectively.This result confirms the efficiency of application of “m Correction coefficient method”. However, it is suggested that the performance of this method be evaluated using a sufficient number of individual hydrographs and their sedimentgraphs in other watersheds.

Introduction With the occurrence of flood, the velocity and depth of the flow in the river increases and the flow enters the flood plains. The velocity difference between the deeper section and the shallow area causes the transfer of momentum between these areas and complicates the flow structure. The formation process of secondary flows and its pattern in compound channels have been investigated by researchers such as:Tominaga & Nezu, 1991. The presence of vegetation on flood plains causes complexity in the analysis of hydraulic problems of compound channels. For example, Hamidifar et al. (2012, 2014), using laboratory measurements, showed that the presence of vegetation reduces the flow through the cross section by about 30%. At the same time as the water level rises during the flood, the deck of the bridges will go under water and the current passing under it will be pressurized. In this condition, the flow field is affected by the presence of vegetation, compound channel and pressurized flow. In this research, the laboratory investigation of these complex conditions has been done.MethodologyThe experiments of this research were done with 3 geometric ratios of the compound cross-section, 3 relative depths, 3 vegetation densities, and control experiments in a compound channel with a length of 10 meters and a width of 1.5 meters. The measurement of the flow velocity parameter, the scouring rate of the bridge pier in the conditions of pressurized flow has been done according to the variables mentioned above.Results and Discussion Comparison of depth velocity and logarithmic velocity distribution in the condition without vegetation on the flood plain, the sign shows that in all sections, the distance between the channel bed and the water surface, the difference between the measured velocity values with the logarithmic distribution of the velocity increases. This difference is due to the presence of the bridge deck and the flow retardation. Also, vegetation causes the depth distribution profile of flow velocity to deviate from the curve of logarithmic flow velocity, and the biggest difference will occur in the upstream area between the interface of main channel and flood plain. This phenomenon increases the amount of apparent shear stress between the main channel and the floodplain.With the increase in the density of vegetation, the percentage of floodplain participation in the total discharge is reduced by 20%. The highest participation percentage of floodplain is about 30% in the state without vegetation. In different densities of vegetation with an increase in relative depth from 0.3 to 0.5, the percentage of floodplain participation in the total discharge is less than 10%. With the increase in the density of vegetation, the difference between the percentage of floodplain participation in different cross section widths has decreased.ConclusionsThe findings of recent research to check hydraulic parameters can be summarized as follows:- Increasing the density of vegetation increases the longitudinal velocity in the main channel and decreases it in the floodplain.- Longitudinal velocity and averaged- depth velocity in the main channel in the case without vegetation is lower than the case with vegetation.- Increasing the relative depth increases the percentage of floodplain participation by an average of 5%, and the increase in vegetation density causes a decrease of 17% in the floodplain participation.- With the increase in the vegetation density of the floodplain, the velocity changes in the floodplain decrease compared to the main channel.- Examining the profiles of the depth distribution of the flow shows that due to the presence of the bridge deck and the retardation of the flow, the depth distribution differs greatly from the logarithmic distribution of the velocity . This is despite the fact that in the conditions without the presence of the bridge deck, this amount of difference reaches its minimum.- The presence of the bridge deck and the creation of backwaters reduce the difference in flow velocity in the main channel and floodplain upstream of the bridge, and this in turn reduces the strength of the secondary currents between floodplain and the main channel.- The difference between the global average velocity of the flow and the local velocities increases the slope of the (a-1) and (b-1) lines due to the flow retardation.

In most buildings, concrete and steel are used side by side, and according to the type of loads, various stresses are created at their interface. When the repair layer is in direct contact with the steel or reinforcement, the stresses caused by the shrinkage of the mortars as well as temperature changes have a negative effect on the adhesion between the repair mortar and the steel. According to the CEB-FIP MODEL CODE standard, the shear adhesion between mortar and simple reinforcement is equal to τ=0.3√(fc). But it has not provided conditions to consider the type of implementation. Considering that shrinkage causes shear stresses at the interface of mortar and steel, therefore, in this article, by using the in-situ twist-off test, the shear adhesion strength between mortar and plain steel has been evaluated under different processing conditions. The results of the twist-off test show that the above equation is used if the sample is under processing until the moment of the test, otherwise there will be a big drop in the amount of adhesion, which even reaches 50%. The results of the shear adhesion strength obtained from the twist-off test for the samples that were processed in water until the time of the test, at a young age are almost equal to the equation provided by the CEB-FIP Model Code standard. At older ages, the shear bond strength results from the twist-off test between mortar and steel are on average more than 10% higher than the equation provided by the CEB-FIP Model Code standard. For the samples that were processed for a week and then left in the open space, it is observed that there is a big difference between the shear adhesion strength obtained from the twist-off test and the equation provided by the CEB-FIP Model Code standard. For practical cases where processing is usually done for about seven days, it is suggested that the shear adhesion strength between steel and mortar is measured for samples that have been subjected to wet processing for at least one week and prepared and stored under appropriate conditions. According to the equation, τ=0.15√(fc) should be considered. The amount of 90-day shrinkage for mortar treated in water and left in open space is 0.1083 and 0.2679%, respectively. The amount of shrinkage for mortar processed in water is 59% less than the shrinkage of mortar left in the open space.

In this work, some thermodynamic properties of nanoparticles, nanofluids containing a base fluid, and nanofluids with two different bases were assessed at the pressure range from 0. 1 to 45 MPa and a temperature range from 273 to 363 K. this study focuses on nanofluids such as Al2O3, CuO, Co3O4, SnO2, TiO2-Rutile, TiO2-Anatase, ZnO and the base fluid containing H2O, Ethylene glycol and polyethylene glycol (with a molecular weight of 400). The used Equation of State (EOS) is the Tao– Mason (TM) equation of state which is based on statistical mechanics and its parameters can be calculated by a potential function. According to the quantum properties of nanoparticles, a quantum Correction was used to calculate the second virial coefficient. To consider the polar effects of the material, the Morse three-parameter potential function was used which is more flexible than the usual two-parameter potentials functions such as Lenard Jones 6-12. Initially, the pure-component parameters of nanoparticles were fitted to the saturated liquid density data, and then the parameters were used for mixtures. Also, a binary parameter was fitted to consider the interactions between two different molecules in the mixtures. In total, from 1181 data points examined, the average absolute deviation between the calculated densities and the experimental ones is of the order of 0. 5%. According to the results, this equation of state has good accuracy for calculating and predicting the density of nanofluids.