The accurate estimation of the design Precipitation is one of the requirements for the construction of hydraulic structures, which is done by various methods of frequency analysis. Classical methods of fitting observational data use the assumption of constant parameters of distribution functions,while, many studies have been done on non-stationary data due to factors such as climate change. Therefore, this paper aims to use the functions of non-stationary parameters-if necessary-and compare them with the stationary assumption of the maximum daily precipitation data of the Atrak river basin. Mann-Kendall test and White test were used to check the non-stationary in the mean and variance of annual data. The Generalized extreme value distribution function was also fitted to the data time series. Among the 24 stations with long-term data, 5 stations with trends and 6 stations with variance non-stationary were detected. Evaluation criteria including Akaike (AIC), Bayesian (BIC), Root mean square error (RMSE), and Nash-Sutcliffe efficiency (NSE) coefficient was determined under stationary and non-stationary assumptions, for all stations. The results showed that in all stations with non-stationary, considering the mentioned conditions in the analytical calculations is a good choice. Also, the lower (5%), median (50%), and upper (95%) limit values with the return period of 100 years with both assumptions were determined and compared with the classical maximum likelihood method. The underestimation of the maximum likelihood method compared to the Bayesian method used by using Markov chain Monte Carlo (MCMC) in parameter estimation was observed. Also, Akaike criterion provided better results among the used evaluation criteria.

Shaikh ul-Islam Seyyed Na’im Son of Afifa, under the pseudonym of Sahab is one of the poets of the Return Literary Period in Iran whose only manuscript is kept in the Center for the Great Islamic Encyclopedia. In Diwan of Sahab, there is a diverse range of literary types and genres such as lyrical poetry and its subcomponents such as elegy and eulogy. Sahab used Khorasani Style in his eulogies and Araghi Style in his Ghazals. He praised his contemporary Qajar Kings, i.e. Mohammad Shah and Nasser al-Din Shah as well as some princes. Local governors lived in the city of the poet were also included his eulogies. Sahab illustrated Karbala Event in his elegies. Since the frequency of those elegies is high in Sahab’s poetry, he can be called an ideological poet. In his Diwan, Saghi Nameh and Akhawaniyeh which are under the lyrical genre are observed as well. Apparently he died in 1307 AH in Neiriz City.

Estimating of crop water requirement (ET) is one of the important parameters in the designation process of irrigation systems. If in this process, mean amounts of the evapotranspiration for a several years period are being used based on the meteorological data, then the occurrence probability of that will be 50%, while it is possible that the plant will face a water challenge (stress). Therefore, in order to prevent such a problems, it has been suggested to estimate the evapotranspiration rate with different probabilities so that based on the plant geaus and agricultural management, the ET with the paper occurrence probability can be chosen and then used in the designation process of the irrigation systems. In this paper, using data from Hashem-Abad Synoptic station, Gorgan, ETo and ETp of the main agricultural products of the region for every julian day of the year in the long-term has been computed. Then, through the moving average method, the beginning and the final data of water requirement maximum circles (1 to 30 days) were been defined and Log-Normal distribution, ETo and ETp with different probabilities for these circles, were estimated. Analysing ETo and ETp amounts with different probabilities revealed that by increasing the irrigation circle the mean daily evapotranspiration decreases. Also for a specific circle by increasing the probability level, the mean daily evapotranspiration increased.

To assess the financial market risks, the correlations between the prices of the individual stocks are of crucial importance. They change significantly in time due to trader's market expectation changes and the relation between business units' changes .This means the volatility of financial time series is non-stationary and fluctuate quickly. Non-stationary can lead many challenges for estimating the covariance estimation, which is main parameter in risk assessing. In addition, the impact of large event shows that we cannot easily assume normal distribution for financial time series especially when we observe large event frequently in the case of crises. In fact, non-stationary leads heavy tails distribution and this can affect the quantities we wish to measure. In this regard, we review the changes of covariance matrices of returns related to companies listed on the Tehran Stock Exchange during the period of 2011-2019 and obtain the multivariate distribution of returns, in terms of taking into account non-stationary and using the method of random matrices. The results show that the theoretical distribution obtained from the random matrix method with two approaches, heterogeneous and homogeneous covariance matrix, can well describe the experimental distribution of returns of Tehran Stock Exchange companies.

In this paper, data of the annual fastest wind speed in Bushehr station in south of Iran were used and graphical and numerical methods were applied to compute scale and local parameters of the Gumbel Distribution Function (GDF). Then, different return periods for the annual fastest wind speed were estimated. In the estimation process of local and scale parameters, Standard analytical procedures such as Method of Moments (MOM), Method of Order Statistics Approach (OSA), Least Squares Method (LSM) and Maximum Likelihood Method (MLM), were used. Numerical computations show that the Method of Moments (MOM) provides better results compared to other methods and computed values for the scale and local parameters in estimation of annual fastest wind speed in Bushehr station are the best estimation. Computations of the annual fastest wind speed for return periods of 25, 50, 100 and 1000 years, estimated to 29. 7 m/s, 32. 8 m/s, 35. 8 m/s and 45. 9 m/s, respectively. Moreover, we can say that, in the confidence level of 95%, every 207. 2 and 82. 9 years, annual fastest wind speed of 39 m/s and 35 m/s can happen, respectively.

literary complexity, linguistic vulgarity and assigning of Safavid period poetry to decline were among the main causes of the emergence of literary return current whose dominant thought was returning the poetry and literature to their past boundaries of authority and glory. Following this thought, imitation of the past literary works, especially the works of the poets and writers of Khorasani and Iraqi styles, and sometimes the Voghooie style, was spread. In this regard, one of the forms of imitation and following was composing the sketch poems. The sketch poems were those that were designed and ordered by the owners of the associations and literary circles, and the poets were asked to compose a poem based on the rhyme and rhythm of that sketch poetry. Although being important in examination of the style of the return period poetry, this issue has not been specifically addressed. So, the authors of this paper have tried to describe, criticize and review this topic in a content analysis method (descriptive-analytical approach). Accordingly, it has been determined that composing the sketch poems is one of the important forms of imitation and following of the predecessorschr('39') literary styles prevalent from the early Safavid period to the late Qajar dynasty. The oldest sample of composing this kind of poetry dates back to the era of ShahAbbas government and The composing this kind of poetry was also prevalent in the Qajar dynasty, especially the governments of Fath Ali Shah and Nasser al-Din Shah. Neshat Isfahani, Saba Kashani, Sahab and Mojmer are among the most famous poets of this kind. Furthermore, since this kind of poetry was composed based on a certain plan, it was mainly imitative, repetitive, and obligatory although lacked creativity and innovation, but, because it was in accordance with the dominant ideas of the literary return current, it plays a great role in returning the poetry to the past periods.

Freezing is one of the weather phenomena that almost happen in parts of the east Azerbaijan province such as Maragheh causing significant losses in agriculture, industrial activities, and transportation. The end of this research is studying of distribution and freezing return periods in Maragheh synoptic station during 48 year period (1343-1391) based on the minimum daily temperature. The methods of this study is Gumbel distribution method, three parameter log-logistic method and log-logistic method to analyzing probability of freezing parameters occurrence (starting date, ending date, length of the freezing season, length of the growing season).The Results of the computation of the spring and fall freezing return periods show that the first freezing in the fall starts on 10 Aban and the last freezing end on 17 Farvardin. Also analyzing of the beginning and end freezing trend shows that fall's freezing have an ascending trend, in other words, the dates of the occurring fall freezing goes ahead and spring's freezing have a descending trend. It means that, the dates of spring freezing go back. Therefore, length of the cold season according to the global warming becomes shorter.

The general judgments regarding the quality of the poetry in the return period are general and hypothetical, and their proof needs more and more detailed investigations. The structure of the poetic image is a collection of various rhetorical materials that resulted by the special vision and language of each poet; In other words, the result of analyzing the geometry of a poetic image will be various art structures that have played a role in the formation of that structure. One of the necessary tools for a thorough examination is the knowledge of stylistics, which, with its two characteristics of frequency and analogy, is a good criterion for examining the poetry of poets of any period. The current research, which is written in a quantitative-statistical way and with a stylistic approach and by examining the geometry of the images of the sonnets of six prominent poets of the return period (Mushtaq Esfahani, Hatef Esfahani, Azar Bigdeli, Soroush Esfahani, Sabai Kashani and Fethullah Khan Shibani), tries to avoid common generalizations regarding the similarity of the poetry of the poets of the period of return to the poetry of the poets of the previous styles, by presenting accurate statistics and It is clear about the amount of use of individual and combined artistic structures by each poet, apart from determining the level and quality of the structure of the images in terms of simplicity or complexity, by comparing the geometry of the images of the sonnets of the poets of this literary school with the structure of the images of the Iraqi and Indian style poets. The results of this research show that as we move away from the Indian style (and the Safavi era) and get closer to the Qajar period, the number of composite artworks and the percentage of complexity of the images decrease and the scale of individual artworks and images decreases. It is simply added; For example, the structure of Mushtaq's lyrical images (the first and closest poet of this research to the Indian style) is different from the geometry of other poets' lyrical images of this movement and is placed in the same line as the structure of Iraqi style images, but the structure of lyrical images Shibani's poems are much simpler than the structure of the images of other poets of this movement, as well as Iraqi and Indian poets.

In this article, we are going to introduce the style of "literary return" and its formation. Then, we shall look into the language peculiarities of the poems of the period.For certain, any changes in the style of poetry are affected by political and social conditions. Literary customs, addressees, and personal matters of the poet can be influential in the formation of a style as well. The "style of return" was founded during the two historical periods of Afshariye and Zandiye (1148-1200) H. This school of poetry formed its doctrine in terms of political, social and cultural changes during half a century. Later, in the time of Ghajariye, it found its firm reality in a school of poetry. The poetic language of the period is generally based on research and imitation of the Araghy- Khorasany style. By carefully studying the works of the poets of the time, we can see that they were not skilful enough with grammar and other rules of poetic language. So the language of their poems is simple and rudimentary. However, it seems that they were affected by the Hindu or Afshariye-Zandiye style. In this article, we will explain this in details.