milad yazdanpanah

In this paper, control of shimmy vibration of aircraft nose landing gear is presented. In this regard, the NARMA-L2 neural controller and a robust controller using a fuzzy method are designed and compared. The efficiency of these controllers was measured by comparing the results obtained from CTM and PID controllers. Using the NARMA-L2 neural controller, maximum effort and settling time are improved whereas using fuzzy controller overshoot of the vibration response improvement in the closed-loop system was observed. According to these results, a large part of the design requirements can be solved by the implemented controllers.

Small vibrations (Shimmy) are lateral and torsional vibrations in the aircraft wheel that excites itself and cause instability in fast functions; which can damage the aircraft's landing gear and its fuselage, as well as, in commercial aviation, this may harm passengers. Therefore, controlling and damping these vibrations is essential. For this purpose, the present study has designed a controller using the NARMA-L2 type neural method to prevent small vibrations in the aircraft's landing gear. The controller as mentioned above has a high capability against parameter uncertainties and external disturbances. To check the performance of the proposed controller, the vibration response of the system was simulated by MATLAB software, and its efficiency was measured by comparing the results obtained from RCTM and Proportional-Integral-Derivative (PID) controllers. The obtained results show a significant improvement in the performance of the closed-loop system with an effective reduction of vibrations as a result of using the proposed controller.

With no doubt, each society adopts its own programs for teaching depending on the lifestyle and communicative and technological skills. In traditional nomadic and immigrant societies, people acquire the survival skills through experience and participation in affairs. However, education and knowledge acquisition for this group of people entail specialized institutes and schools, which has appeared into obsolete kuttabs or maktabs in Iran's tribal communities. After the modern schooling, teaching in nomadic areas was first based on the teaching rules governing the other public schools until the World War II. Following the Point Four Program, assisted by the USA, nomadic teaching was incessantly followed under the title of nomadic education and proceeded until the establishment of the Department of Education for Tribes (DET) in 1969, serving as the first official organization of nomadic education. Taking these into account, the present qualitative study aims to spotlight the Qashqai tribe using the historical method and a library-based document analysis technique. The purpose is to visualize the trend of evolution of the teaching policy before the official nomadic education in Iran. In doing so, the study assumes that teaching has been continuously regarded in different periods by mobile kuttabs or maktabs, and school

Every society needs an appropriate educational system which is attuned to its existing and emergent political, socio-economic, and cultural structures. The nomadic life has remained one of the important ways of life in Iran, and therefore the authors explore the education of nomadic peoples in contemporary Iran from the first Pahlavi period to the Islamic Republic by focusing on a case study of Qashqa'i  tribe and using a sociological-institutional approach. Based on various needs and specific functions, the institutions are established and evolved as time goes on; and their sustainability in reality depends on their functions and the competence or effectiveness of carrying out their assigned tasks. Similar to other social and political institutions, the formation and expansion of institutions involved in the policy planning, formulation and implementation of education programs in a nomadic society have undergone numerous developments throughout the course of history. According to the Statistics Center of Iran, there are diverse tribes who are divided into clans with different history, dialects, ethnicity, and cultural customs. The ‘wandering’ nomads in 2008 made up 1.4 percent of the population, and owned about 29 percent of  Iran’s livestock species of sheep and goats. However, no precise data is available in regards to their access to education. The nomadic families who have settled down in villages, towns and cities have presumably  access to schools for their children, but those who live in remote areas of the country have to be provided with "mobile" tent schools and instructional materials such as books. As more nomads have gradually changed their traditional lifestyle, their  access to schooling has been through the official educational institutions, particularly during the Islamic Republic era. In this qualitative case study, the authors use the existing historical records and data collected in previous studies based on a variety of research methods ranging from participant direct observation, interview, to events data analysis and discourse analysis by prominent researchers in order to answer the following questions: 1. What has been the characteristics and functions of the nomad education program in Iran since 1925? 2. Why and how is the nomadic education system in Iran influenced by the government power structure? In the research hypothesis, it is claimed that the mentality of the Iranian intellectuals and politicians towards the tribal issue has influenced the development and implementation of education programs for nomads in Iran which has  led to social and cultural changes, and has had important implications such as the concentration of power in favor of the central government, decline of power of tribal hierarchy, assimilation and identity solidarity of the nomads. In Iran, formal education and training programs were adopted to create educational opportunities for the nomads who had held on to their traditional ways of life, and often had to cope with many social and economic problems as compared to sedentary and less mobile populations. In the past, the central government had tried to transform the nomadic and seminomadic tribes into town dwellers, farmers and livestock producers with the goal of helping them to gain economic self-reliance under the watchful eyes of the authorities who were concerned with national security threats. One of the aims of such policies had been the gradual elimination of the tribal powers. After the fall of Qajar dynasty (1789-1925) and the failure of the constitutional movement to implement reforms and tribal plans, the Pahlavi dynasty (1925-1979) inherited the idea that the population of tribes and nomads should be settled and tribal way of life should be abolished. Nomadic education was one of the tools of assimilating the tribal communities, and transferring tribal loyalty to the central government away from the subnational tribal leadership structure. The tribal policies pursued from the Qajar period to the First Pahlavi era (1925-1941) were aimed at establishing a modern state, and increasing socio-economic development of the country. Due to the weaknesses of government infrastructure, transformation efforts were based more on the use of military means than the cultural ones. The  plans failed to bring about the desired changes, and in the aftermath of the Anglo-Russian invasion of Iran and the subsequent political crises which led to the abdication of the ruler in August 1941, Iranian nomads once again became influential in the country's politics. The Qashqa'i  leaders were among the main players in southern Iran until 19 August 1943. However, the central government during the second Pahlavi Era (1941-1979) gradually became powerful with the help of Truman’s Point Four Program and planned to  counter the growth of communism among the nomadic and rural communities by a cultural policy which included nomadic education program. This new policy was more successful compared to the past attempts to address the tribal issue. The nomadic education was able to act as an ideological instrument to promote nationalism, patriotism, loyalty to the country, flag-waving, and admiration for the ancient Iranian culture. Therefore, the education of ethnic and tribal mobile communities such as nomadic herders and pastoralists should be seen as an institutionalized arrangement made by the central government to perform functions such as tribal communities' displacement and their settlement in population centers, legitimation and concentration of state power, and the destruction of the power base of the tribal leadership, and cultural assimilation in the name of development.

The present study aimed to investigate the belief and ritual system among Qashqai people with emphasis on the "Stove and Fire" principle. The idea (hypothesis) considers that the belief and ritual system among clans of Iran, especially conglomeration of clans and tribal communities provide some important tool to recognize their values and beliefs, mentality, identity, roles, and social status, based on their lifestyle. There is a meaningful and continuous relationship between the Qashqai people and the totality of Iranian identity. Many of these beliefs and rituals have played an essential role in social functions as well as identical and political functions. Therefore, the current study seeks to answer this question that what are the socio-political functions of the "Stove and Fire" principle, as a belief and semantic system, among Qashqai nomads.