In terms of education, the population of Iranian immigrants abroad has created one of the highest quality communities far from home. Many of these people pursue postgraduate studies after migrating to developed countries. The return of these people to Iran will increase the country's human capital and pave the way for development. The aim of this research is a future-oriented analysis of the reverse migration of academic elites. The reverse migration of academic elites observes the phenomenon of the return of individuals after obtaining a Ph. D. abroad. In this study, the Causal Layered Analysis (CLA) method and semi-structured interview tools employed to examine metaphors/myths, discourse/worldview, and macro-social causes of reverse migration of academic elites in the minds of university faculty members of universities affiliated to the Ministry of Science, Research and Technology who have studied abroad. Due to the relatively low salaries of university faculty members compared to other countries, the impossibility of employment in universities, the duality between personal and social life of individuals in Iran, concerns about the future of children, complexity and lack of transparency, economic and political instability of the country, the bureaucracy of the university employment process and the impossibility of working in the country's industrial sector, the process of reverse migration of academic elites to the country, do not have a clear vision in the minds of the interviewees. At the same time, in an attempt to present alternative futures, factors such as economic prosperity, political stability, restoring lost confidence in social, cultural, economic, and political factors, engagement with other countries, recognition and adaptation to new realities of society, improving and strengthening the relationship between universities and industry, and modernizing the conditions of employment and recruitment of faculty members have been emphasized.

Summary: Reverse time migration (RTM) as a new seismic imaging method solve the two-way wave equation and has been implemented through a three main steps including forward and backward wave-field extrapolation from the source and receiver and employing a proper imaging condition. RTM model all types of wave without any dip limitation. This is very important regarding the drawbacks of ray-based and one-way wave equation imaging methods in properly imaging the complex geological media. Despite the above superiorities, low frequency artifacts especially in large reflection angles (60 to 90 degree) are the main drawback of RTM which cover and reduce the migrated image quality. Therefore, the aim of this paper is to improve the imaging condition as the heart of RTM to suppress the low frequency artifacts and use the useful information of the large reflection angle domain (60 to 90 degree) and produce a high quality image. This was achieved by presenting a new imaging condition including a weighted function based on the reflection angles. Finally, the RTM results using the new proposed imaging condition was presented and compared with the results of some conventional and modern similar methods. Introduction: Seismic imaging is based on numerical solutions to wave equations, which can be classifi ed into ray-based (integral) solutions and wave fi eld-based (diff erential) solutions. In complex geological structures such as subsalt media, the velocity variation leading to complex multi-pathing reflections. Hence ray-tracing may fail to image the subsurface properly and cannot image steeply dipping refl ectors corresponding to the velocity model. On the other hand, one-way wave propagation extrapolates wave-fi elds vertically and cannot accurately model waves that propagate nearly horizontally. they fail to handle waves propagating at wider angles, especially those near or beyond 90° . RTM directly solves the full (two-way) acoustic wave equation and incorporates all type of waves propagating in different directions. Hence, it has proved to be the preferred imaging algorithm in many geologically complex basins. RTM can image the complex geological media properly which is beyond the limits of one-way wave equation-based migration algorithms. Nevertheless, RTM has its limitations. The major drawback is the low frequency artifacts produced by the image condition (zero cross-correlation at lag) or by strong velocity contrast which is the main topic of this paper to be developed to suppress the RTM artifacts. Methodology and Approaches: To suppress the RTM artifacts, the imaging condition as the heart of RTM was developed. A new presented imaging condition includes the separated down-going and up-going wave-fields and a new weighted function based on the reflection angles. It implemented to suppress the low frequency artifacts for large reflection angles and maintain the useful information for the same reflection angle domain through an advance procedure. Results and Conclusions: RTM results using the presented imaging condition indicates that the low frequency artifacts was suppressed properly and the subsurface geological structures was imaged as well as possible in final migrated image I comparison the other seismic imaging methods.

Introduction: There are several methods of seismic migration and the main objective of those is to place the reflectors in their true positions. One way for seismic migration is the algorithms that directly apply imaging conditions; on the other hand, the inversion-based imaging method implemented through different strategies to obtain a better depth model that fits the observed data. One of these inversion methods named least square migration solves the inverse problem through direct migration and demigration. The least squares migration has the main advantage that it can gradually reduce errors caused by initial migration. In this paper, particularly the reverse time migration (RTM) is used as an operator of migration and demigration. Therefore, two numerical schemes are developed to implement least-squares migration with the reverse time migration method. Methodology and Approaches: The Helmholtz equation is used to derive the forward modeling operators named reverse time migration (RTM) operator with the Born approximation that is donated as linear inversion. Thus, the linear least square reverse time migration (LSRTM) is the inversion procedure to obtain the final image. LSRTM uses the RTM results as the initial reflectivity model and Born modeling to simulate the seismic data. The reflectivity model is updated by calculating the differences between observed and calculated data through the conventional an adaptive gradient. After multiple iterations, the differences are minimized and this is taken to suggest that the fi nal refl ectivity model refl ects the real subsurface interface. Results and Conclusions: The results indicate that the LSRTM through an adaptive gradient procedure can successfully produce the subsurface migrated image free of artifacts including the steep dip structures during a reasonable computational cost.

Reverse migration refers to the migration from urban areas to rural areas. The census conducted by the statistical center of Iran regarding the immigration from urban to rural areas provide data which actually reflects the total number of immigrants returning from the urban areas to their place of origin, rural areas, together with the immigrants born in the city but immigrated to the villages forever. The purpose of this research is studying and doing comparative analysis of return migration, from urban to rural districts, on the provincial scale based on the descriptive-analytical method. The information required by this research were collected from 2006 & 2016 censuses data, official website of statistical center of Iran. According to the results obtained by the present research, the migration balance between rural and urban areas has resulted in a new equilibrium state in contrast with the decade before that. In terms of volume, the provinces of Tehran, Khorasan Razavi, Mazandaran and Gilan have attracted 33% of the entire reverse migrants. In all provinces of the country, a negative correlation coefficient of 0. 477 between the deprivation index and the ratio of reverse migrants than the rural population, has shown that the provinces with more deprived rural areas in terms of environmental, social, economic, have fewer reverse migrants. . Finally, ARC and GIS software indicate that the spatial interactions throughout the country in terms of return migration is very strong in favor of densely populated cities of northern Gilan, Mzandaran, Bushehr and to some extent around the metropolises of Tehran, Mashhad, Ghom, as well as Semnan, Yazd and Ilam. Therefore, in the spatial planning for the Iranian regions, the rural districts in Chaharmahal and Bakhtiari, Zanjan, Kurdistan, North Khorasan and Hormozgan are of a higher priority.

Reverse migration is one of the main flows of rural-urban linkages. This flow is formed by some pushing forces in cities, such as high living costs and air pollution, as well as some pulling factors in rural areas, such as low living costs, pleasant weather, and the opportunity to spend leisure time. It also has various effects on both the origin and the destination of the migration. The purpose of this paper is to analyze the status of reverse migration in terms of both spatial and temporal dimensions. This research is applied research and in terms of the method is exploratory, descriptive and analytical. The data used in this research has been obtained from the Statistical Centre of Iran and has been analyzed during two 5-year periods: 2006-2011 and 2011-2016. Data analysis was performed using spatial statistics techniques in the Arc Map software environment. Research findings at the national level show a relative decrease in reverse migration over five years from 2011 to 2016. At the provincial level, 28 provinces of Iran have experienced negative growth and a relative decrease in reverse migration, and only 3 provinces have experienced positive growth. Findings from spatial analysis at the county level of Iran also show the spatial concentration of a large number of reverse migrations around the two metropolises of Tehran and Mashhad. Also, high values of the ratio of reverse migration to the total number of immigrants are concentrated in the central and northern regions of Iran.

Rural reverse migration is an emerging theme and phenomenon of which second homes are the most important; About half a century has passed since its re-emergence and expansion. During the current years, reverse migration, especially of rural type, is significant. The most crucial goal of this research is to identify the infrastructural drivers of this phenomenon in the form of artificial intelligence in Yazd province. The research method used is the combined method "quantitative and qualitative". The statistical population of this research includes all villages with rural development documents of Meybod city in 8 villages, two of which were surveyed. Findings indicate that the existence of communication infrastructure such as the Internet, virtual social networks, the use of new technologies to earn money and maintain security, the existence of extensive hereditary grounds and houses for construction, the support of the Islamic Council and Dehyari and the low cost of construction due to the existence of inherited land and low interest loans, as the most important strengths, components of socio-cultural conflicts between residents and migrants, lack of agricultural and drinking water, especially in summer and lack of companionship And the children of individuals as the most critical weaknesses, components of short distance to the center of the city and province, use of facilities with low interest rates, return of youth and educated in the form of reverse migration, the possibility of using new technologies in business and life Despite the educated and well-known youth and reputation of Yazd region, the most critical opportunities and components of creating a recreational and leisure village, the possibility of putting pressure on the resources and facilities of the village and the spread of fashion culture, consumerism in villages as the most important threats in reverse migration is identified

Extended Abstract Introduction The dominant form of migration in developing countries, including Iran, is from the village to the city. However, during the past two decades, another pattern of migration, reverse migration, has occurred in rural areas in such a way that in the findings of the general population and housing census of 2012, the number of reverse migrants is higher than the rural-urban migration. In the whole city of Natanz, due to its location in the center of Isfahan province, the city of Isfahan has access to the markets of Isfahan, Badroud, Khaled Abad, Natanz, and Targhroud. On the other hand, the physical development of Isfahan and its economic and social relations have various characteristics. During the past years, reverse migration flow to urban and rural settlements has taken place in temporary and permanent forms. The general goal is to investigate and analyze the role of reverse migration in the economic development of villages in Natanz. From a practical point of view, the results of such research provide solutions to the country's managers to implement better planning to prevent migration and encourage migrants to return. Reverse migration is when people return to their first place (origin) after a long residence in another place (destination). In other interpretations and definitions, reverse migration is considered a reaction to creating attractiveness in rural areas, which emerges through the establishment of income in activities such as agriculture or animal husbandry, retirement, and sometimes due to the hardships of urban life,a process in which a person or persons, due to various reasons, return to their first place again from the place they have chosen as their new place.   Methodology This research is descriptive-analytical. The samples were based on Cochran's formula, and to complete the discussion, Krejcie and Morgan's sample size determination table was also used. Information was collected from 381 individuals across 24 villages through field surveys using a researcher-made questionnaire.   Results and discussion Regarding gender, 84. 78% of the sample was male, and 15. 22% were female. Also, 94. 75% were married, and 5. 25% were single. The age group included 3. 93% 20-30 years old, 17. 85% 31-40 years old, 28. 08% 41-50 years old, 27. 30% 60-51 years old, 22. 83% 61 years old. Out of the total sample, 2. 62% are illiterate, 27. 82% have a diploma, and 36. 49% have a bachelor's degree, master's degree, or higher. One sample t-test was used to study the factors affecting reverse migration. In order to evaluate the dimensions of the factors affecting the migration from the city to the village, the items were first oriented and it was combined as an average,considering the 5-point Likert scale in the research items, the number 3 was chosen as the theoretical median to evaluate the importance of the dimensions of the factors affecting reverse migration from the society's point of view. This research has been studied at a confidence level of 95%. Given the frequency of variables used for leveling (47 variables in the first step) and the importance of evaluating more important variables and determining the weight and importance of each variable, the factor analysis method was used. In this research, the exploratory factor analysis method was used to summarize data and identify causes. In order to determine the suitability of the collected data for factor analysis, the KMO coefficient and Bartlett's statistic, which were significant at the 1% level, were used, so they were suitable for factor analysis. By benefiting from the factor analysis technique in the principal factor analysis method, 6 factors with eigenvalues greater than 1 were extracted, and the variables for evaluating the dimensions of the factors affecting reverse migration were grouped in these factors based on the factor loading and after orthogonal factor rotation using the Varimax method. The 6 factors explained a total of 71. 682% of the total variance related to the variables of factors affecting reverse migration. In this research, the basic theory is the theory of human capital, which was proposed by Larry Shasta. According to the theory of human capital, the return migration of people is formed in the hope of benefiting from more prosperity in the village. The result of the research shows that the reverse immigrants have been able to be effective in the economic sector in both capital and idea sectors. In fact, the innovation of this research can be that the economy is based on reverse migration, and if there is a correct plan and vision in the programs and among managers, it can cause the growth and development of villages.   CONCLUSION Population relocation and migration is a sign of the continuity of human life, which has a history as old as humankind. People who consider the continuity of life, social and economic activities, and the field of effort limited and short for themselves in a geographical place start to migrate. Among the spatial-location features related to rural areas, "lack of welfare and civil services" has played a special role in the appearance of the driver of migration to the city. However, with the development of welfare-civil services and the increase in the income of the agricultural sector and belonging to the original birthplace, the return of immigrants to rural areas is provided. The results of this research are related to the research of Shaojun Chen and Wurong Liu (2020),urban repulsion factors and attraction factors play a role in the migration from the city to the countryside. It is associated with Stockdale's (2014) studies concerning urban repulsions, such as the inability to create jobs in cities and rural attractions, such as age and retirement. It is associated with the studies of Edival (2015) about urban repulsions such as lack of job security and rural attractions such as retirement. It is associated with the studies of Langroudi et al. (2012) in the field of rural attractions, such as obtaining more income, increasing relative welfare, and improving human dignity for migrants returning to rural areas. According to the studies of Afrakhteh et al. (2015), in economic and cultural-ethnic causes, the least impact on reverse migration from the city to the village is associated.   Funding There is no funding support.     Authors’ Contribution All of the authors approved the content of the manuscript and agreed on all aspects of the work.   Conflict of Interest Authors declared no conflict of interest.   Acknowledgments We are grateful to all the scientific consultants of this paper.

Excessive migration from rural areas to cities is one of the most challenges of most developing countries like Iran. A significant way is encouraging reverse migration to rural areas. So, many studies have focused so far on identifying the factors affecting reverse migration. This study tried to identify the factors affecting reverse migration from urban areas of Kermanshah to its rural areas. This survey used researcher-made questionnaire to collect the data. The data analysis was done using the descriptive-analytical method. The statistical population constituted the households that have migrated to different rural areas of Kermanshah over the last 5 years. Questionnaires were randomly distributed among 384 households, and 371 questionnaires were completed. The data were analyzed using exploratory factor analysis. The results showe 9 factors that could explain 62% of the variance of 38 items, pertaining to factors affecting reverse migration from urban areas to rural areas in Kermanshah: housing, costs-income of the families, cultural-biological issues, level of access to educational and health services, the physical factor, job opportunities in rural areas, sense of belonging and being native, and tourism attractions and handicrafts. Moreover, the least affecting factor on reverse migration policies was supporting policies of governments for the villagers. From among the variables, the availability of educational facilities for children (having a factor load of 85%) and the governments’ support for the agricultural sector regarding providing seeds, fertilizers, pesticides, and so on (having a factor load of 84%) have the greatest impact on reverse migration, respectively.

Migration is a phenomenon common to all countries and reverse migration is reflective of migration from urban to rural areas. It is a phenomenon that gradually increases and could have consequences in the society. The purpose of this study is to investigate environmental, physical, economic, and social causes and consequences of reverse migration to rural areas of Buin and Miandasht. This research is descriptive-analytical in which the data were collected using the library-field method. From the 5 rural districts of this county, 5 villages that had the most reverse migrant households were selected. Then, a sample of 290 reverse migrants was determined and questioned using the Cochran method. According to descriptive data, environmental-physical aspects with a mean of 40. 14 have been the most important factors of migration. The results of the confirmatory factor analysis and the path coefficient of the main causes show a 40% influence of social causes, 41. 7% of economic causes, and 48. 2% of physical-environmental causes on reverse migration. The results of the independent t-test for all variables (i. e. positive and negative consequences of reverse migration) also showed that the average negative effects are physical (29. 86%), economic (14. 09%), and social (20. 90%). The average positive effects are physical (14. 38%), economic (24. 68%), and social (30. 13%). In examining the results, the change in natural landscapes with an average of 3. 96 had the greatest environmental-physical impact. The improvement of educational indicators with an average of 3. 44 had the greatest social impact and increasing land and housing price with an average of 3. 45 had the greatest economic impact.

Reverse migration is a spontaneous thing that, if it continues, can be a very effective way to revitalize villages and give new life to the identity and function of the village. In this study, due to the necessity of the issue, it tries to analyze the factors affecting the growth of reverse migration to the suburban settlements of Najafabad. This research is applied in terms of purpose and analytical-descriptive in terms of method. The required data was collected through documentary methods and field survey.The statistical population of the study is 11662 people and 3550 households living in rural areas of Sadeghieh district, of which 370 household heads were selected as the sample size using Cochran's formula. The instrument was a researcher-made questionnaire whose validity was formalized and confirmed by a panel of experts and its reliability was calculated based on Cronbach's alpha formula for different dimensions between 0.922 and 0.710. The questionnaire was distributed based on the distribution in proportion to the population of the village and was done completely randomly among the heads of households. One-sample t-test was used to analyze the results and Spss software was used for all analyzes. The results show that the main factors in the population of suburban villages of Sadeghieh district are due to (economic) factors with the impact of the role of job necessity and proximity to the workplace, (social) factors with the impact of returning to their homeland, (cultural) factors Indigenous residents of their martyr, as a rural example of Hajiabad with 101 martyrs, are the factors (environment) of low population density, factors (infrastructure) of the village being located on the roads of the province and the city. According to the results, practical suggestions were presented.