The aim of this study was to investigate cloud’ s characteristics and some effective physical indices on rainfall in Mashhad. We initially studied cloudy sky in Mashhad by consulting meteorological yearbook of 1986-2010. Density and prevalence for medium and low clouds as well as density, prevalence and average for vertical clouds (type 2 cumulus and cumulonimbus) were calculated for every month. This study shows that in Mashhad the highest frequency of low and medium clouds occurs in cold and rainy months during winter and spring, while most of the clouds with vertical development occur in spring. We also studied freezing level in clouds in both rainfall and no-rainfall cases, using skew-T diagrams and radiosonde data during 1992 to 2011. The condition considered here was overcast sky. We obtained a regression equation in order to specify role of physical indices (CAPE، SI, K، PWT) in precipitation. At first, rainfall days of Mashhad were extracted from Khorasan Razavi meteorological department archive (1992 to 2011). On these days, six hour rainfall (00 to 06 Z) were determined. Then, instability and physical indices were obtained from radiosonde data of Mashhad weather station. A regression equation was estimated by analyzing the relationship between natural logarithm of six-hour rainfall as dependent variable and instability indices as independent variable. This research determines which relationship between some indices with natural logarithm of six-hour rainfall is nonlinear. Analysis of regression variance shows that regression was significant at 99% level. This means that at least one of the indices has a linear relationship with logarithm of six-hour rainfall. In this equation, due to significant level, CAPE and PWT were removed. Most relationships were found between SI and natural logarithm of six-hour rainfall.

As the temperature of oil transfer pipeline walls is reduced to cloud point, wax tends to deposit on internal side of tubes. Wax deposition may be prohibited by mechanical, chemical and thermal methods. As the period of oil recovery proceeds and volumetric flow of oil production decreases, the holding time of oil in pipe would increase, thereby wax deposition may increase. In this research using a designed dynamical set up, the extent of wax deposition was studied for four oil samples (B, C, D, E) provided from Iran reservoirs. The oil samples contain wax weight percent in range of 2-3 %. The result of studies, presents that the discrepancy between fluid temperature and pipe temperature is the most important factor influencing the extent of wax deposition. Increasing the volumetric flow of the fluid leads to expulsion the majority of wax from the fluid, but it decreases the tendency of deposition on pipe surface. The physical properties of the fluid exclusively could not evaluate the amount of deposition and wax deposition is affected by operational conditions too. The deposition issue is not excluded only to wax precipitation; rather the deposit has to be studied from general view considering overall oil constituents.

The reverse chemical co-precipitation method was used for synthesis of the pure phase multiferroic BiFeO3 (BFO) nanoparticles. Influence of different pH values on the microstructure and magnetic properties of the BFO nanopowders was investigated. The phase formation and the existence of impurity phases (like Bi25FeO39 and Bi2Fe4O9) have been studied using X-ray diffractometry (XRD). The morphological features of the nanopowders were characterized using field emission scanning electron microscopy (FESEM) and the presence of absorption bands at 400 to 3600 cm-1 was investigated by Fourier transformed infrared (FTIR) spectroscopy. The magnetic evaluation of the synthesized powders was measured using vibrating sample magnetometery (VSM). The XRD results showed that the BFO powders have R3c crystal structure for all samples and also the diffraction patterns are perfectly indexed to the standard XRD card of BFO. The FESEM micrographs showed irregular shape and average particle size of 71 to 95 and 182 nm for the as-synthesized powders with the pH values of 8. 5, 9. 5 and 10. 5, respectively. The magnetic hysteresis loops indicated antiferromagnetic (weak ferromagnetic) behavior for all samples at room temperature. Whereas the particles size of as-prepared powders were lower than the spiral spin cycloid (62 nm) and because of high surface-to-volume ratio of nanoparticles, which causes more uncompensated spins from the surface, the weak ferromagnetic behavior has been observed.

Ferric ion is a strength oxidant and its precipitation is an undesired phenomenon in the bioleaching process. Previous studies showed that it considerably occurs in bioleaching operations even at optimum conditions. Although there have been many reports on the Fe3+ precipitation, no study has made a mathematical modeling of the affecting parameters. The aim of the present work is the development of a model that represents the impact of some parameters on the Fe3+ precipitation.The polynomial model was developed. The resulted model presents the positive effect of all parameters on minimization of Fe3+ precipitation; particularly, the effects of pH and iron concentration, which are more significant. The validation of model was confirmed using F-test (P<0.001) and the coefficient of determination (R2=96.84%). The optimum values of parameters were determinedas: pH=1.5, Temperature=35.5oC, iron concentration=20g/l, pulp density=15% (w/v).The non-linear nature of the modeled response for Fe3+ precipitation was explained by a second-order polynomial equation. Also it was observed that by increasing the considered parameters, precipitation rate was increased. The severity of the effects of the parameters at the studied range was as follows: pH and iron concentration>temperature>pulp density.

In this research in order to identify the most effective jet stream pattern, creating pervasive rain falls in Iran during the period 1971 to 2008, from turning approach to the environmental approach was used. For this purpose, first of all, an elemental analysis with component based approach on wind speed data with the balance of 300 HP for 12 of Zolo was done by demystified data of United States of America Atmospheric Prediction Center. The analysis showed that 8 main components are able to explain 85% of the diffraction of data. Then, by applying a hierarchical cluster analysis with Ward's method on the scores 8, mentioned component during the 3098 days under study, eight prevailing jet stream was detected on Iran. Then for every pattern, using the interclass correlation, one day with the most correlation was chosen as the day of an agent of that pattern. The next step is to determine the most effective model jet stream leading to rainfall, the amount of rainfall of 32 synoptic stations in the center of provinces, along with maps in heights, Omega, 1000, and 500 hp and map the convergence of moisture flux for levels of 700 and 850 hp for each of the days of the agent was investigated. The results showed that the pitch of strong jet stream in fourth pattern with a speed of 65 meters per second at the level of 300 hPa in southern of Iran along with formation of through cold Chali on the Caspian Sea, simplify the conditions for the convergence of the lower levels of Iran atmosphere, and influx of moisture from the Mediterranean Sea along with along with unstable conditions of high atmosphere, causing pervasive rain in Iran

In the pastures, floods often happen due to surface runoff and violent storm. Initial soil water content has a direct influence on the infiltration capacity and as result on surface runoff. Hydrological models are strong instruments to investigate the main physical processes involved in the watershed. In the present study regression models, obtained from relationship between independent and dependent effective variables on runoff production. Through modeling used in this study, the daily precipitation and water discharge data for the period from 1974 to 2000 collected, refined and analyzed.Subsequently the pertinent models were recognized with using the concept of dynamic modeling statistical software's Excel 2003 & SPSS 11.5. The analysis of results showed that the effective time of antecedent precipitation and the most effective daily precipitation on daily discharge. The results indicated that the antecedent and daily precipitation were affected on the daily discharge of Tangrah pasture watershed in duration of different months significantly. It was also found out that the daily discharge was affected by the precipitation occurred respectively before three days while this is contrary to emphasizes of other common methods of estimate of runoff that was based on effect of precipitation of fifth previous days on daily discharge due to specific governing conditions on study watershed. The present study emphasizes determination of exact quantity of effective antecedent precipitation in different places attention to effective spatial & temporal changes on output discharge of watershed.

The purpose of the present study was to investigate the effect of generative learning teaching based to pattern cognitive Load on the memorization math of 7th grade students of in the academic year of 2021- 2022. The research method is quasi-experimental with pre-test and post-test with four groups: two control group and two experimental groups. The statistical population of the study consisted of all 7th grade male and female students of District 2 of Mashhad city that 112 person sample was selected by single stage cluster sampling method. The subjects in the experimental group involved in generative learning based to cognitive Load in 16 sessions and the control group did not receive any interventions. The research instrument consisted of a 20-questions researcher-made test. To analyze the obtained data, Multivariate analysis of covariance and SPSS version 24 software were used. The results showed that generative learning teaching based to approach cognitive Load have a positive and significant effect on 7th grade students' memorization math. Based on the findings, it can be concluded that one of the effective training on math memorization students is the use of generative learning on the based load cognitive pattern.

Westerlies are the main driver of rainfall in Iran, and its spatial variations are an important parameter to identify the spatial and temporal differentiation of rainfall, especially its role in the temporal distribution of autumn rainfall at the same time as the beginning of the water year is very important. Early and late fall rain is a good criterion for starting the cultivation of autumn (rainy) crops. In order to explain the role of variations in atmospheric circulation on the time delay of autumn rains, rainfall data, weather patterns, wave indices, intensity and high pressure level in the subtropical region were used. The results show the weakening of the westerly wind waves due to the spatial variations of Subtropical High Pressure(STHP). The decrease in tides in October has been associated with the time delay of rainfall and the shortening of rainy days. The delay in the high-pressure southerly regression is associated with a 20-day delay and a decrease of 7 mm of monthly rainfall and finally a decrease of 15 mm of autumn rainfall. From a synoptic point of view, the time delay of precipitation is associated with the positive anomaly of geopotential height and high pressure strengthening. The time shift of the effective autumn rainfall (from October to November) is accompanied by an increase in rainfall due to the provision of suitable instability conditions. The time delay of autumn rainfall is associated with the shortening of the rainy season, the reduction of autumn and annual rainfall and finally drought.

One of the most important issues related to rainfed wheat cultivation is the date of the First Effective Precipitation (FEP) which can provide soil moisture for cultivation. The current study aims to evaluate the variability and probable trend in the date of the first effective precipitation and the synoptic conditions that lead to its occurrence in northwestern and western Iran. Therefore, precipitation data were extracted from Iran’ s Meteorological Organization. First precipitation with a value of at least 5 mm and duration of one to two consecutive days, associated with another precipitation occurring less than 10 days apart, was selected as the first effective precipitation. Then, the trend of first effective precipitation was investigated using Man-Kendall test and linear regression method. Finally, geopotential height, wind speed and humidity data (ERA-Interim) at 850 and 500 hPa levels were obtained from ECMWF website to identify synoptic patterns of the first effective precipitation by cluster analysis method. The findings reveal that more than 90% of the first effective precipitation has occurred during October. Accordingly, Ardebil, Sanandaj, Khorramabad, Kermanshah, Zanjan, Orumieh, Tabriz and Hamadan stations had earliest climatic average of the first effective precipitation date during the period of 1987 to 2016, respectively. Despite the high annual variations regarding the occurrence date of first effective precipitation, evaluating the trend of the first effective precipitation by Mann-Kendall test at the significant level of 5% show that there is no significant trend in all studied stations. Furthermore, synoptic patterns including the short trough, omega block, cutoff low and the Mediterranean long trough are identified as responsible patterns on the occurrence date of the first effective precipitation. Among the patterns, omega block has been associated with widespread rainfall at the studied stations due to greater access to moisture and unstable conditions caused by the cold weather.

The flood hydrographs preparation is essential in order to provide the necessary information to control flood projects. However, getting access to accurate flood information is too difficult and expensive due to practical problems and the lack of suitable hydrometric stations. In addition, providing and analyzing unit hydrograph is considered as a usual and useful method for flood studies in watershed scale. Since the theories of making and applying the unit hydrograph cannot be provided, the investigation on the effects of mentioned theories and especially linearity and time stability on the precision of derived unit hydrograph is important. In spite the importance of variability of unit hydrograph, there are a few studies in this field. Towards this attempt, this study has been formulated in Kasilain watershed with the aim of investigating the unit hydrograph variability in different effective time bases using the hydrograph and hyetograph analysis of floods reports recorded during last 33 years. So that the range of differences between peak discharge, base time and time to peak of representative 2h unit hydrograph and those obtained from 0.25 to 6h unit hydrographs were found about 0.75 to 281, 6 to 36 and 0 to 50%, respectively.