فهرست مطالب ali arman

Nowadays, by expanding the application of thin layers in industry and medical sciences, their fabrication methods have also received attention. One of those methods is the vaporizing material method with the help of an electron gun. The most important part in the electron gun is the electron optic, which is responsible for producing and accelerating electrons, so that it becomes possible to vaporize refractory materials in a shorter period of time by better modifying and controlling the electron beam (the shape and diameter of the electron beam) at the target location. The reduction and control of the beam diameter in this evaporation source depends on various parameters such as device geometry, magnetic field intensity, electric power, etc. Therefore, in this research, the effect of those parameters was investigated by conducting experiments and using finite element and modeling software. The simulation results revealed that the effect of the effective parameters on the beam diameter can be predicted to a good extent, so that the diameter of the electron beam decreases by changing the geometrical shape, size and displacement of the output beam components. Then, the new electron gun, compared to the existing prototype, is optimized by applying these changes in the construction of the device and conducting experiments, and its beam diameter is reduced by 40% to be more focused.

One of the effective methods to reduce the kinetic energy downstream of hydraulic structures are the aprons. The horizontal aprons is one of these structures in the river that are often used downstream of stilling basins. At the time of execution, the apron and the riverbed are at the same level but when there is a flow in the boundary between the connection of the river bed and the aprons, scouring occurs, which causes the destruction of the apron and there is a possibility of destroying other water structures. In this research, using Flow 3D software, different scenarios were simulated for five Froude values of 0.32, 0.3, 0.25, 0.2, and 0.15, three Manning roughness coefficients of 0.025, 0.02, and 0.014 per particle diameter of 1.8 mm for horizontal aprons. In this numerical model, the graph of scouring depth changes in relation to Froude numbers in different roughness coefficients, the effect of Froude numbers on the location of the scour hole for different roughness coefficients of the horizontal aprons, the shear stress changes in relation to the length of the horizontal aprons with different roughness coefficients and different Froude numbers, as well as Erosion changes with respect to the length of the horizontal aprons were calculated with different roughness coefficients and different Froude numbers.

Nowadays, the use of diamond-like carbon films has been considered for industrial and biological applications, so in today's research, by introducing impurities (metallic or non-metallic), they are looking for new structural and mechanical properties. Therefore, this research discussed the fabrication and characterization of silver nanoparticles in a diamond-like carbon (DLC) thin film bed on various metal substrates using the simultaneous radio frequency plasma sputtering and chemical vapour deposition method. Therefore, the films were fabricated from the silver target in an environment of a combination of acetylene and nitrogen gases at different working pressures. The morphology of the film was examined using an atomic force microscope (AFM) according to the standard 25178-2: 2012, and the statistical results obtained from the AFM data showed that the surface topography of the film at different pressures changed according to the substrate nature so that the samples prepared at a working pressure of 18.5 mTorr had the highest surface roughness compared to other samples. After that, the fractal properties of the prepared films were theoretically checked, and all the films have multi-fractal properties—the results of the multi-fractal analysis of the film satisfactorily complied with other AFM statistical data. Moreover, with the help of EDS and Raman analysis, the structure formation, the presence of carbon, nitrogen, and silver elements, and the existence of a carbon-like structure were confirmed.

Due to the importance of the topic in the fluid transfer industry, the way of pipelines across the width and bed of the rivers has been considered especially in recent decades. In practice, the passage of pipelines through meandering rivers and river bends is unavoidable. In this research, local scouring of buried and semi-buried pipe in 90-degree mild bend under different scenarios was investigated. The results of this research can help the functioning of rivers and their interaction with structures in the river such as buried and semi-buried pipelines, predicting the amount of water washing around them and using its results in the design and placement of these pipelines.

The laboratory model on which the scenarios of this research are based includes an arc-shaped channel located in the hydraulic laboratory and physical models of the water science and engineering department of Razi University. In this arc-shaped flume, the length of the upstream span is 5.4 meters, the length of the downstream span is 4.5 meters, the inner radius is 1.6 meters, the outer radius is 2.1 meters, the height is 0.6 meters, and the floor width is 0.5 meters. In order to check the correct functioning of the physical model and to trust its results, an experiment was conducted without the presence of the pipe buried in the bend. In this experiment, the flow descent number equal to 0.32 and sediments with a uniform grain and a diameter of 0.85 mm and a thickness of 15 cm were placed in the flume bed. After conducting the test for 6 hours and not observing the movement of the bed load, the pump was finally turned off and after the complete drainage of the flume, the bed profile was measured.

The effect of the placement angle of the repeller pipe relative to the mild arc (θ) on the scouring pattern
The results showed that by placing the pipe in the repulsive state, the amount of scour after the pipe and under the pipe has increased compared to the attracting state. According to the placement angles, it was observed that in repulsive mode, with the increase of the placement angle of the pipe in the bend, the amount of scouring after and under the pipe has increased. The effect of the placement angle of the attracting pipe relative to the mild arc (θ) on the scouring pattern In the absorbant state, it was observed that by approaching the beginning of the arc and reducing the placement angle of the pipe due to the non-alignment of the flow direction with the pipe direction, the amount of scour after the pipe decreased, but the process of scouring under the pipe was observed as in the repulsive state.The effect of pipe placement depth on scouring pattern By increasing the depth of pipe placement, it was observed that the effect of the pipe on local erosion has decreased; Even in some simulation scenarios, the placement of the pipe in the depths with the ratio of the placement height to width of the channel of 0.06 buried pipe has no effect on the local erosion. It can be concluded that at depths equal to or greater than The ratio of placement depth to channel width is 0.06, the effect of local scouring caused by the buried and semi-buried pipe is minimal, and as a result, it causes the least damages.

The results showed that by placing the pipe in the repulsive state, the amount of scour after the pipe and under the pipe has increased compared to the attracting state. According to the placement angles, it was observed that in repulsive mode, with the increase of the placement angle of the pipe in the arch, the amount of scouring after and under the pipe has increased. However, in the absorbiant state, it was observed that by approaching the beginning of the arc and reducing the placement angle of the pipe due to the non-alignment of the flow direction with the direction of the pipe, the amount of scouring after the pipe decreased, but the process of scouring under the pipe was observed as in the repulsive state.

The emergence of the Covid-19 has threatened physical and mental health and has negatively affected the economy of all countries in the world as well as the people’s daily life. All countries of the world have imposed restrictions such as travel, quarantine, school closures, social distancing measures. In the current situation, information and communication technologies and cyberspace play a significant role in establishing communication between the people. Most of the countries in the world use remote working systems and online mechanisms of education letting students and staff stay and work from their homes. There has also been a very high demand in activities such as telecommuting, electronic health care systems, food delivery and online shopping. The cyberspace criminals have taken the Covid-19 Pandemic as an opportunity to launch attacks against financial interests and promote their nefarious purposes.

During the outbreak of the Covid-19, ransomware, phishing attacks and botnets have targeted the banking systems, personal virtual space education, health care and resources such as the confidentiality of patient records which have endangered privacy and have compromised the confidentiality and integrity of data. People are falling prey to cyber-attacks through Covid-19 related content.

In this article, several important cyber security threat methods that existed or could occur during this pandemic have been examined. We have also discussed the concerns in the midst of this privacy-centered pandemic and finally examined some of the ways to deal with these threats. Abidance by the ways and methods revealed through this research will enable the people to keep safe in the cyber space to a noticeable degree.

Cavitation is one of the most important problems that may occur due to high flow velocity in dam spillways. In order to predict of dam spillway structure during operation, Azad dam spillway hydraulic model has been modeled in Tehran Water Research Institute.

In this study, using computational fluid dynamics in the form of a finite volume method used in ANSYS FLUENT software, flow modeling in these channels, and a fluid volume model (VOF) in a three-dimensional state, including two-phase flow of water and air, used for Considering current turbulence, k-ε model has been used. In order to confirm the results of the model, a comparison was made with the results of a hydraulic model implemented without the aero-damping system of Azad spillway.

Then, in order to confirm the location and number of aeration systems, two scenarios (two and three aeration systems) including step ramp (RAMP) on the floor and the wall of the duct with a suitable slope and the installation of the aeration slot in the wall have been used, which sends air near the floor And the walls will be.

Then, by checking flow parameters such as speed, pressure and cavitation index, overflow with two aeration systems was confirmed as the best option.

Estimating the amount of sediment load that a specific stream can carry is one of the main subjects of sedimentary research. Shahroud River in Qazvin province is one of the important rivers in Qazvin Province which plays an important role in providing agricultural water in the region, especially providing water to the Sefid Rud dam. In this study, using the HEC-RAS model to study the erosion and sedimentation status of Shahrood River paid. Also, using maximum discharge measurements with a 25-year statistical period in Rajai Dasht hydrometric station located on Shahroud River and using Smada software discharg with different return periods and for calculating the hydraulic modeling of the river, were used. Finally, the model was run for 25 years (507.93 cubic meters per second). After calibrating the model for river hydraulic conditions and modeling inappropriate inappropriate flow conditions, the boundary information and depth were introduced into the model. Using the transfer of sediment ratios, the sedimentation capacity of Shiroud River was calculated. Comparison between the obtained results and the measured data showed that the Ackers-White equation with a mean error of 16% in the range was better than other functions.

Ample research has been done on optimization methods for the exploitation of reservoirs in the form of a specific optimization. In this type of studies, a certain series of flow is provided for the reservoir during the operation period and the release from the reservoir to downstream is optimized under such circumstances. They are certain drawbacks for these models. First, optimal solutions cannot be generalized for other possible inputs to the reservoir. Second, in the event of a change in the flow of input into the reservoirs, it is likely that the optimal solutions are not efficient and the operation of the system in the form of an optimization algorithm should be performed again. In such circumstances, one of the solutions is the use of intelligent methods such as support vector machines to apply the results of system optimization in real time. The main goal of this study is to integrate artificial intelligence methods such as support vector machine with NSGA-II optimization algorithm to convert it to real time. In this structure, contrary to the conventional design of the scheduling, in the event of a change in the flow of input, there is no need to perform re-optimization to understand the optimal coefficients. Instead, the extraction relationship of the support vector machine can be based on the input to the reservoir (at the beginning of the month), the volume of water storage in the tank (at the beginning of the month), reservoir storage changes and downstream needs in the current month to yield optimal release rates in real time.

 Using hydrological information and physical and hydraulic characteristics of the river route for flood routing in different cross sections of the river, impact of forecasting on the occurrence and flow peak flow and successful implementation of flood alarm systems and forecasting flood volume downstream of the river. Given the importance of predicting flood hydrographs, especially in floodplain rivers, and the lack of sufficient information and statistics at some river basins, this may result in hydraulic methods in such rivers. This study aimed to compare the results of flood routing using the numerical model MIKE11 and the support vector machine method. This comparison was based on three parts: peak discharge, flood volume and baseline hydrograph time.

In this study, based on physical and hydraulic information of the route, hydraulic routing of flood hydrographs between two hydrometric stations of Holeilan and Sazebon was conducted in a distance of 67 km from Semareh River in Ilam province, Iran. For this purpose, 365 cross-sections with an approximate distance of 200 m were considered for flow routing. The geometrical data of these sections and their physical characteristics in terms of their distance (in kilometers) were entered in the MIKE11 upstream interval. River bed gradiation curves were used to estimate the roughness coefficient in each section. These coefficients were optimized during model calibration and validation. In addition to the main river, discharge included two major sub-branches located along the river. The flow rate of these branches was defined as sub-flow of internal boundaries in the model. For upstream boundary conditions, hourly hydrograph data of Holeilan station and for downstream boundary conditions, flood hydrograph data and discharge values of rating-curve station at the last river crossing were entered. The SVM model was then used to predict the flood hydrograph at the output of the interval based on the input flood hydrograph data. Based on the delay time of flood passage between Holeilan and Sazebon stations, flood hydrograph data at Holeilan station located upstream of 0, 2, 4, 6, 8, 10, 12 and 14 hours delays as input layers and hydrograph discharge values at the location of the Sazebon station was considered as the output layer and the model was calibrated and validated using recorded hydrographs. Finally, the results of these two models were compared. Flood hydrographs were also upstream with different return periods and flood hydrographs were predicted at interval outflows with different return periods.

 Based on the results of both calibration and validation, it was found that the support vector machine method predicted the peak discharge relatively better than that of the MIKE11 method, but with considering statistical indices, such as RMSE which calculated all hydrograph discharges, the results of the flood hydrograph prediction in MIKE11 model had relative advantages over the support vector machine model. This model also simulated the volume of floods more accurate. However, in order to compare the behavioral pattern of predicted flood hydrographs with different return periods, especially floods with the peak discharge more than the peak discharge hydrographs used in the calibration and validation phase, flood hydrograph values with period various returns as inputs to the study area were entered into each model at Holeilan station and flood hydrographs were predicted at the output of the interval and at the corresponding station location with the corresponding return period. Because the classification of data in the training phase is adjusted to discharges less than 25 years, the SVM model was able to predict only hydrographs with 2, 5 and 10 year return periods. But after the calibration and validation, the Mike11 model was able to predict the hydrograph well with the return periods of 2, 5, 10, 25, 50 and 100 years.  

The results showed that the SVM model was somewhat better than the Mike11 model if the only criterion was to predict peak flow within the range of historical discharges. But this model was not accurate for predicting partial events with a return period of more than ten years. Given the statistical indices of RMSE, NRMSE, and NASH, which use all hydrograph discharges to evaluate results rather than using peak discharge, the Mike11 model provided better results than the SVM model. The Mike11 model performed better than the SVM model in predicting partial event hydrographs with different return periods.   Acknowledgment The authors of the article extend their thanks reviewers for reviewing and improving the structure of the article, and also to the National Surveying Agency for providing the maps of the Seymareh River.

Digital world as well as cyberspace are undergoing a rapid change and evolution. Emerging new technologies like artificial intelligence, machine learning and robotics have raised fundamental ethical challenges related to the privacy and data protection in virtual space by the controllers. This study explains general data protection regulations (GDPR) and then analyzes its impact on Iran's regulations and citizenship rights in cyberspace.

In this analytical study, using library method, the ethical dimensions of privacy and protection of cyber data are discussed and analyzed.

The study of the GDPR and the compilation of country-specific laws based on religious principles showed that combining these two perspectives could reduce abusing and doing crime in cyberspace. Therefore, these ethical and legal considerations should be included in the laws of the majority of countries, and in particular the Islamic Republic of Iran, based on the GDPR.

These ethical concerns and responsibilities should be included in the laws of most countries, in particular the Islamic Republic of Iran, in the near future by the authorities, based on the provisions of the GDPR. Also, training staff on cyber security, the use of relevant security software and the provision of free educational resources can be effective in preventing crime and utilizing cyber-space, especially in financial matters.

Rivers are considered as one of the main sources of water and energy for human beings, and are considered as the aorta of human societies. Protecting the river bank against the erosion and degradation caused by the water flow, using various types of flow control structures is considered as a common method in river engineering science. One of the most important flow control structures is spur dikes that divert the flowing attack from the sides and critical areas and direct the flow towards the central axis of the river. Several researches have been conducted concerning the effect of spur dikes in protecting the river bank in bends such as: Barbhuiya and Dey (2004), Nasrollahi et al. (2008), Zhang et al. (2009). The purpose of the present study is to study the flow and sediment pattern in a 90-degree mild bend, with and without spur dikes with different permeability percentages.

Flow in river bends is three-dimensional, the combination of secondary flow and longitudinal flow in rivers leads to the formation of helical flow which is the main cause of erosion in the outer bend and sedimentation in the inner bend. So far, many numerical models regarding flow patterns in rivers have been introduced and available to river engineering scholars. Moges et al. (2010) simulated the hydraulic and sediment flow in Meander Rivers using SRH-2D two-dimensional model and eventually determined the best equation for predicting the water surface profile and bed level changes in sediment situations. Naji Abhari et al. (2010) studied the flow pattern in a 90 degree bend. The results of their study results showed that from the beginning of the bend till the 30 degrees angle the maximum velocity is close to the inner wall and from the 30 degree angle till the end of the bend the maximum velocity is diverted to the outer bend. Maghrebi (2012) studied the turbulent flow pattern in a longitudinal range of Karoon river, containing two 180 degree steep bends using MIKE21FM and CCHE2D models, the results showed that that both models simulate the flow pattern accurately. The aim of the present study is simulation of the flow pattern in a 90 degree mild bend using CCHE2D and SRH2D models.

Reliable prediction of boundary shear force distributions in open channel flow is crucial in many critical engineering problems such as channel design, calculation of energy losses and sedimentation. During floods, part of the discharge of a river is carried by the simple main channel and the rest is carried by the floodplains located to its sides. For such compound channels, the flow structure becomes complicated due to the transfer of momentum between the deep main channel and the adjoining floodplains that magnificently affects the shear stress distribution in floodplain and main channel sub sections. In the present study experiments were conducted in a compound rectangular section with different discharges and 3 different aspect ratios. The results showed that in each aspect ratio, shear stress increases by increasing the water level. It is also shown that by increasing the aspect ratio, shear stress is decreased significantly.