Introduction: Longitudinal bars are stream geomorphic features formed in the central part of river channels. Usually they are classified and range from simple to compound the obstacles based on the shape and position of the river which showed absence of multiple phases and deposition of sediment transport during the various flows are included. The form of these sedimentary bars is long and drop form. Sediment particle size varies from pebble to fine-grained particles such as gravel and sand. Sediment particle size in the upstream part of these bars is larger and downstream side is smaller. These deposits are usually formed the imbricate that shows the flow of water is during the flood period. Longitudinal bars play a significant role in the process of braiding. Hence, in this research, we analyzed longitudinal bars formation and its role in river pattern change. The study area is located in Lavij roud catchments in Mazandaran province, south of Noor city and northern central Alborz. This basin located from 36o 16' to 36o 27' 30" degree of north latitude and from 51o 58' to 52o 05' degree of east longitude. The area of basin is about 116 square kilometersMaterials and methods: Methodologically, three reaches of stream channel were selected which contain longitudinal bars.Reach 1: In this reach, between 50 and 90 percent of cases, the channel is located in the valley margins. The river channel from one side of the valley is located on the sidelines and on the other hand is a floodplain.Reach 2: This reach of river is entirely alluvial and valleys to a depth of approximately 15 meters are filled from alluvial deposits. This reach was limited to the southern part of the fault North Alborz with a rapid and then it is subsidence. Hence is filled with alluvial sediments.Reach 3: In this reach, between 10 and 50 percent of cases, the channel is located in the valley margins. Gradient is less than 3 percent. Bankfull channel discharge is estimated 13.5 cubic meters per second.Survey of channel performed with the use of GPS and positions of longitudinal bar are determined in channel stream. Then, some cross sections are mapped and size of sediment determined with Pebble Count Method in the reaches. Bankfull discharge identified using field evidence. Then entrainment analyzed with boundary shear stress, critical shear stress and bed relative stability functions.Results and discussion: In the studied reach, the total shear stress at all levels is more than the critical stress (the bondary) when the current bankfull is flown. Hence, the river has the ability to carry sediments flown existing longitudinal bars and channel bed is the current bankfull. If the number bed relative stability is larger of one, shows bed stability and everything is much more to show that sedimentary particles in the bed on the floor will remain stable. In the studied reach, this ratio is less than one. Hence this relationship shows that in the bottom sediments of streams in the current bankfull or less are removable and the bed in case of sediment movement is unstable.There is no doubt that existing longitudinal bars in river channel change could lead to direct and meander pattern to be braided. Therefore in sections of reach 2 because of existed midpoint bars channel is divided into several parts.Conclusion: Low values of bed form shear stress show that a large part of the river's energy is used to overcome the resistance of bed forms. The bed relative stability ratio less than 1 in this reaches represent low stability of sediments in the river's bed. Hence, longitudinal bars form in wide channels and the flow lower than bankfull lead to much sediment supply and decrease of competence limit. Number of longitudinal bars in some reaches indicated that river pattern shifts from straight to meandering which leads to more instability of the channel.

in this research, their effects on the flight of airplanes were investigated. The study area is the country of Iran, and the flight routes of Kermanshah, Ahvaz and BandarAbbas to Tehran. The research data includes maps of the Vertical Transect (profile) of the jet stream, the daily average of the Zonal wind (U-Wind) and meridional wind (V-Wind) components for the winter period of 2018 through NOAA/NCEP environmental databases. Also, flight route information was received from FlightRadar24 and Flightaware systems. First, by using Vertical Transect maps, the days containing strong U-Wind were extracted, and the average position of the core of the Jet streams in the Zonal and meridional wind components, the Tropospheric level of 200 HP was detected. The list of flights was prepared, and the Zonal Wind maps were produced. Finally, the height of the flights was compared with the level of the currents of the Jet streams, and the influence or lack of influence of the Jet streams on the flights was studied. According to the results of the research, all the Jet streams caused turbulence for all flights, and they caused a decrease in the speed of flights between Ahvaz and BandarAbbas to Tehran and an increase in the speed of flights between Kermanshah and Tehran according to the direction and type of Jet streams. It was also found that all the Jet streams had a speed of more than 90 knots, so the capacity to create tension and turbulence such as CAT was seen in them

The awareness of floods and estimating the debris flow is a fundamental step for assessing risk and planning in the watershed. The village of Sijan, located in the Southern Alborz, is one of the areas threatened by debris flows. The research aimed to estimate the volume of debris flows along 700 m of a stream of Sijan Village time range from 2018 to 2021. The study method included surveying the stream in two-time intervals, which involved one concrete and four gabion checkdams, and calculation of erosion and sedimentation happened via debris flow using the Civil-3D software. Results showed that five check dams had 823 m2 and 750 m3 area and volume, respectively. Debris flows covered 25500 m2 after the flood in 2019, in which the estimated erosion and deposition volumes were 7250 m3 and 10100 m3 according to the elevation difference technique. The Sijan stream channel experienced sedimentation and erosion along the northern and southern banks. Implemented watershed management measures have played a vital role in mitigating the risk of debris flows, especially at the concrete check dam.

Technological changes and enhanced human abilities in exploiting of mountainous areas, and the need for economic diversification of human settlements located in mountainous areas has led to the expansion of rural tourism (in combination with natural tourism) which can complement and encourage productive activities and provide the basis for achieving sustainable development. The present study has been conducted with the aim of investigating and analyzing the impact of the dysfunctional institutional structure on the development and consequences of tourism in the mountainous rural areas of Rezvanshahr. This research is applied in terms of purpose and descriptiveanalytical in terms of method. The statistical population consists of mountainous tourist villages (14 villages) in Rezvanshahr district. The results showed that due to the dominance of the dysfunctional institutional structure, the expansion of tourism has led to the unbalanced development of mountainous settlements. While this activity has led to population re-attraction in mountainous villages but due to the dominance of the dysfunctional Institutional structure, it seems that the space lacks any kind of management, proper organization and it is without supervision. In other words, the dysfunctional institutional structure hinders the development of tourism via maximizing individual benefits and it led to the expansion of tourism in mountain villages for personal gain and to the detriment of the nation. While the mountains of Iran are a common natural heritage of all Iranians and this shared heritage and valuable intergenerational wealth must be obsessively managed and protected as much as possible. The effects and consequences of irrational and destructive exploitation of mountainous areas will not only be limited to the mountains but also it will expose the whole society to irreversible social, economic and political damages.

Sequential pattern mining is an interesting data mining problem with many real-world applications. Though new applications introduce a new form of data called data stream, no study has been reported on mining sequential patterns from the quantitative data stream. This paper presents a novel algorithm, for mining quantitative streams. The proposed algorithm can mine exact set of fuzzy sequential patterns in sliding window and gap constraints entailing the most recent transactions in a data stream. In addition, the proposed algorithm can also mine non-quantitative or transaction-based sequential patterns over a data stream. Numerical results show the running time and the memory usage of the proposed algorithm in the case of quantitative and customer-transaction-based sequence counting are proportional to the size of the sliding window and gap constraints.