In the present paper, a new penalization method is proposed for implementation of the rigid surfaces on the Navier-Stokes equations in the vorticity-stream function formulation. In this method, a rigid body is considered as a region in the fluid flow, where the time is stopped. Therefore, by stopping the fluid particles, this region plays the role of a rigid body. In this regard, a new transformation is introduced and applied to the governing equations and a set of modified equations are obtained. Then, in the modified equations, the time dilation of the solid region is approached to infinity, while the time dilation of the fluid region remains unit. In the article, the physical and mathematical properties of modified equations are investigated and satisfaction of the no-slip and no-penetration conditions are justified. Then, a suitable numerical algorithm is presented for solving the modified equations. In the proposed algorithm, the modified vorticity equation is time integrated via the Crank– Nicolson method, and the spatial discretization is performed with the second-order finite differencing on a uniform Cartesian grid. The method is applied to the fluid flow around a square obstacle placed in a channel, the sudden flow perpendicular to a thin flat plate, and the flow around a circular cylinder. The results show that the no-slip and no-penetration conditions are satisfied accurately, while the flow fields are also solenoidal high level of accuracy.

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

Many tubular joints commonly found in offshore jacket structures are multi-planar. Investigating the effect of loaded out-of-plane braces on the values of the stress concentration factor (SCF) in offshore tubular joints has been the objective of numerous research works. However, due to the diversity of joint types and loading conditions, several quite important cases still exist that have not been studied thoroughly. Among them are internally ring-stiffened multi-planar XT-joints subjected to axial loading. In the present research, data extracted from the stress analysis of 81 finite element (FE) models, verified using experimental test results, was used to study the effects of geometrical parameters on the chord-side SCFs in multi-planar tubular XT-joints reinforced with internal ring stiffeners subjected to two types of axial loading. Parametric FE study was followed by a set of the nonlinear regression analyses to develop four new SCF parametric equations for the fatigue analysis and design of axially loaded multi-planar XT-joints reinforced with internal ring stiffeners.

The study seeks to address the importance of urban stream ecosystems from the perspective of urban ecology, human health and social well-being in the context of urban planning. The case study area is Paveh stream in the City of Paveh. The data from the case study area were gathered from questionnaire, existing scientific and library studies and by conducting interviews with residents and authorities. Once the importance of the biodiversity of the stream had been studied based on the existing ecological data, the social importance of the stream and the linkages between human health, social well-being and the biodiversity of the stream ecosystem were addressed.Based on the results of the survey and other sources of information, it was discussed that urban stream ecosystems can be rich in biodiversity and function as ecological movement corridors for species .Urban stream corridors can thus be an important part of the urban green infrastructure .Also we can make the weather fine, extend green space, prepare peaceful environment for residents and bring the countryside effects of nature into cities through improvement of stream landscape.Finally, regarding the finding of this study some suggestions and implications are mentioned to improve the quality of the stream.

Identification of changes in remote sensing images plays an important role in many applications, such as monitoring the growth of urbanization, land use changes, and assessing disasters and natural damages. This process aims to assign the label "changed" or "not changed" to the pixels of two images taken from the same place but at two different times. On the other hand, in the last decade, deep learning methods have attracted the attention of many researchers in this field due to their proper performance in interpreting and processing remote sensing data and the ability to remove feature engineering and extract high-level features from images. In this regard, in this article, an optimal deep learning model has been designed, which increases the accuracy of identifying changes in two-time images due to its hierarchical structure, appropriate efficiency of multiscale features, and effective design of feature transfer. Due to the optimal structure and architecture, the proposed model has higher speed and accuracy of results compared to some popular models such as BIT. Applying the proposed model to the two data sets under investigation indicates an average accuracy of 96% and less complex calculations.

Fast development of Tehran in the last decades is the cause of deterioration of environmental capacities which continues. Stream corridors of northern part of the city which has an important role in optimizing environmental situation are not an exception. This continuous and joint network of soil and water which has been preserved by its consumers and keeps the climate approximately sustainable is prone to distortion gradually. Therefore special consideration to environmental capacities is essential. This article attempts to consider Evin-Darakeh stream corridor as a green infrastructure by describing other green infrastructures. In order to reach this goal planning principles for this stream corridor and the related strategies are explained.

Four streams with different sizes were selected for studying the effects of environmental factors on fish assemblages using indirect (Detrended Correspondence Analysis, DCA) and direct (Redundancy Analysis, RDA) gradient analysis in Golestan province. DCA of presence-absence and relative abundance data showed well gradient and linear model of species variability. In the within-site RDA, environmental factors explained 74. 8 % variability for presence– absence data and 77. 5% for the relative abundance data. Evaluation of two first axis of RDA showed that first axis has a high correlation with habitat characteristics and second axis correlated with channel morphology attributes. Based on RDA diagrams, Paracobitis malapterura and Capoeta capoeta gracilis presented in Zaringol and Tilabad Streams and had a high correlation with percent of in-stream vegetation and percent of cobble in first axis and low flow mean depth and low flow width in second axis. While Alburnoides bipunctatus and Neogobius fluviatilis had high correlation with percent of snag, pool and sand within streams. It should be stated that factors such as the size of the catchment, hydrographical and geomorphological characteristics, and land use change the morphology and stream habitats, and ultimately lead to the removal of some species in adjacent streams.

The fast pace of development of Tehran (a capital city with a population of 12 million and grandiose ideas) over the last 30 years is the major cause of the deterioration of the natural environment and watershed. Stream corridors in the northern part of the city are the major areas for most of the wildlife diversity in Tehran and are easily affected by human intervention. The two major elements of the stream corridors are soil and water. If either of these is affected by human activities the ecosystem will become unhealthy and its natural balance will be unsettled. Therefore special consideration to environmental capacities is essential. This study was conceived on the basis of a phenomenological approach; an extensive literature review on the subject and the case study were also conducted. The research attempts to consider the Evin-Darakeh stream corridor as a green infrastructure by describing the benefits of green infrastructures. In order to reach this goal, planning principles for this stream corridor and the related strategies are explained.