نشریه هیدروفیزیک
سال هفتم شماره 2 (پیاپی 13، پاییز و زمستان 1400)

Understanding surface currents is one of the fundamental topics in oceanography. These currents are caused by various factors such as the presence of prevailing wind, earth  rotation and changes in the density of seawater. In this study, the surface currents of the Strait of Hormuz have been predicted using the Group method of data handling (GMDH) model. To set up this model, the time series data of the surface flow velocity of this basin with an average time step of 5 days have been used. To investigate the surface areas affecting the currents of the Strait of Hormuz, the Persian Gulf basin was divided into 11 areas. Then, using regression analysis , GMDH model and 11 identified area, three marginal areas of the Strait of Hormuz that most affect the surface currents of this strait were selected. Then, using the water exchange model of Jones et al., Presented in 2003, different compounds were extracted from the three identified areas and used as input to the GMDH model. The results showed that the combination of these three zones and using of Jones flow pattern reduce the prediction error index compared to their pre-combined state. Then, due to the presence of anti-clockwise eddy on a basin scale in the months of March to July, the efficiency of the model was investigated by removing these months, which reduced the accuracy of the model with this method. Finally, by data classification, it was found that the GMDH model has good accuracy in predicting high speeds.

Taking into consideration the amassing human requirements for water resources and the use of renewable resources, inclusive of: wastewater, wastewater treatment and wastewater reuse are important points of consideration. Using of an Orbal reactor for COD removal by activated sludge is considered suitable and efficient by numerous literature sources. Furthermore, to improve removal efficiencies, it is interesting to determine the required tools and methods to decrease additional sludge creation. This study aims to investigate the performance of COD removal when a magnetic field is combined within an oxidation ditch Orbal reactor. In this research, two magnetic fields of different strengths, 0.8mT and 1.5mT, were applied to the reactor including several neodymium magnets. Results were achieved and analyzed, upon which the reactor reached a steady state. To confirm validity, results and conclusions from other relatable studies were compared with that of the achieved. The research lasted approximately 100-days and sampling was completed over an 80-days period to observe the effects when implementing a magnetic field compared to that of its absence within an Orbal reactor. This study examined the removal of COD in activated sludge. Results revealed that removal of COD was affected when implementing the magnetic field. Upon application of a 0.8mT magnetic field, removal efficiency of COD increased by 7%, Results indicated, also, that application of different strength magnetic fields had very minor differences.

In this study, the reflective behavior of sloped porous seawalls were investigated experimentally using physical modeling. Regular waves of wide range of heights and periods were used. Tests were carried out for a constant water depth of 0.27m and for different inclinations of seawall (i.e. θ = 45, 60, 75 and 90 ̊). It was found that the parameters of wave steepness, relative water depth, surf similarity parameter and the slope of seawall were influencing in predicting the reflection from the sloped porous seawall. The reflection coefficient (Kr) for sloped seawalls ranged from 0.36–0.77 and for the vertical porous seawall it was 0.59–0.83, whereas for the vertical plane wall, it was almost 1. The reduction in the wave reflection for the sloped seawalls as compared to the vertical porous seawall was about 28%. New empirical equations were developed for estimating the wave reflection coefficients from the proposed seawalls using nonlinear regression analysis. These found were calibrated using SPSS based on the experimental result. The results of this study will be useful in the design of energy dissipating type vertical quay walls in ports, sloped seawalls for shore protection from erosion and sloped caisson breakwaters.

Evaluation of Longshore Sediment Transport Rate in Imam Khomeini port using three examples of meta-heuristics algorithmImam Khomeini port is one of the ports of Khuzestan province in the Persian Gulf, which has 38 active wharves with a length of 7 km, is the largest active port in Iran and the annual dredging volume in this port is about 600 thousand cubic meters, of which about 400 thousand cubic meters is related to the Duragh canal and about 200 thousand are related to other ports of the port, since the sedimentation rate and dredging cost in this port is significant, so, in this study the rate and volume of sedimentation based on field information and modeling obtained from the Ports and Maritime Organization And comparing these values with the results obtained from meta-heuristic algorithms under MATLAB software in two-dimensional flow conditions and also the presence of all parameters affecting the transfer of sediment along the coast in Imam Khomeini port. After combining the three equations of CERK, Kamphuis and Bayram (CKB) and calculating the optimal coefficients and capabilities by Differential Evolution, Ant Colony Optimization and Genetic Algorithm, evaluation and validation with the values obtained from the available field data, coefficient error and computational capabilities Calculated using the root mean squares and bias method, therefore, it was observed that the coefficients and powers obtained from the genetic algorithm that were placed in the CKB equation have the most overlap with the rate longshore sediment transport from field data.

The surface sound channel, as a part of the oceanic boundary layer, is directly affected by atmospheric processes. Sensible heat flux as one of heat fluxes has a major role in changing the behavior of the surface sound channel along with momentum fluxes. The effect of this term of heat flux on the behavior of the oceanic mixed layer has not been studied separately yet. In this study, the effect of sensible heat flux in the presence of wave break and Langmuir circulation caused by summer monsoon of the Northern Indian Ocean has been studied by using a large eddy simulation method for the first time. According to the experiments of the current study, the presence of this flux has no significant effect on the behavior of mean velocity profiles, turbulent kinetic energy budget terms, especially shear production and the transports of turbulence and pressure, and the time series of turbulent kinetic energy. In addition, expectations have been met for a reversible trend in buoyancy flux and mean temperature profile due to positive or negative buoyancy flux at related times. It was also observed that the presence of Langmuir circulation and wave breaking reduced the water surface temperature variability of the sensible heat flux by about 50%, which was due to the influence of sensible heat flux on deeper waters as a result of the presence of wave forcing.

In many studies related to hydrodynamic modeling of seas and oceans, ERA-Interim data have been utilized while the use of ERA5 data has been emphasized more in recent research. Thereby, investigating the difference between the two recent reanalysis data and their impact on determining the physical parameters of the sea is of particular importance. In this research, the surface temperature changes of the Caspian Sea were investigated based on the latest reanalysis data of the European Center for Medium-Term Atmospheric Forecasts (ECMWF), using a developed three-dimensional hydrodynamic numerical model. In this model, the data of wind and atmospheric fluxes were obtained from ECMWF daily database with a spatial resolution of 0.25 and a time step of 6 hours. The model was implemented separately for the ERA-Interim and ERA5 data for a period of 10 years (2009-2018). A comparison of the surface temperatures of the Caspian Sea extracted from the model outputs and satellite images showed that the difference in temporal and spatial changes of the surface temperature was more consistent in ERA5 compared to ERA-Interim. The results showed that the difference in the temporal and spatial changes in the surface temperature of the Caspian Sea in the ERA5 and ERA-Interim was insignificant in the northern basin, relatively significant in the middle basin, and highly significant in the southern basin, so that the data of ERA5 has improved the results of the average annual temperature of the model output by about 7% in the southern basin of the Caspian Sea.

In this research, satellite has been used for the purpose of identifying and finding the waters of the PersianGulf in the Sea of Oman.Finding the subsurface water exiting the PersianGulf through the cross of the Strait of Hormuz by identifying the temperature characteristics of Oman's surface water in the area where the presence of subsurface water in the Persian Gulf has been confirmed in previous studies can lead to finding the subsurface water.In this study, the sea surface temperature data of OSTIA for the studied basin, which is the Persian Gulf and a part of the Oman Sea(47 to59.45degrees of east and 22.60 to 32 degrees of north)was prepared.Then, according to the studies based on the73-year measurement data available in the region and identifying the temperature range of the surface water of the Oman Sea(22.20-23.00C) and the subsurface water of the Persian Gulf(16.00-22.20C)superimposed on each other, the satellite data were filtered. In order to filter the data and draw the figures, it was used coding in MATLAB environment.The results show that the water of the Persian Gulf can be transported to the middle parts of the Oman Sea, surface water (temperature 28.5 to 30 degrees of centigrade)in the cold season in the range of58.5to59degrees of east and in the warm season it advances towards the longitudes up to 59.5 degrees of east.As a result, the infiltration rate of Persian Gulf water in the Oman Sea in the warm season is half a degree of longitude more than the cold season.

One of the applications of solar cells is to supply power to floating buoys. Floating buoys are spherules that are located on the surface of seas and oceans and give different information to vessels. These spherules experience different environmental conditions, so modeling and simulating photovoltaic cells allows us to embed a cell with better efficiency and performance in them. In this paper, we study the parameters of the single diode model so that we extract the I-V, P-V diagrams and characteristics of cadmium telluride (CdTe) photovoltaic cell designed with three layers (CdTe, CdS, SnOx) through SCAPS software and using the Ant Colony Optimization (ACO) algorithm, we obtain the parameters of its single diode model. The objective function in this paper is Root Mean Square of Errors (RMSE). The best value obtained after 30 runs is 5.2217 -10 5-10 in 2.46 seconds per repetition, which indicates a very high fit of the simulated model and shows a significant advantage over many algorithms that have been done so far. The above optimization has been done with 200 iterations, 30 populations and 84 points on a server platform with 32 GB of RAM and 30 processing cores.

In this article new micro-scale hydrophone sensor has been introduced, designed and modeled. Proposed structure is absolutely feasible by current MEMS technology. Mechanical structure consists of two micro-scale arms which together hang a plat. In length of each arms embedded Mosfet transistor placed which on its’ gate plate very thin layer of piezoelectric material, PZT-5A, has been placed. Incident acoustic wave cause mechanical stress which induce surface charge on the interface of piezoelectric and gate layer. These charges will modulate transistor’s channel resistance and finally with employing electronic circuit electric current variation transfers to voltage variation. Simulation results indicated sensitivity of -160 dB in frequencies well below first resonance. In this article new micro-scale hydrophone sensor has been introduced, designed and modeled. Proposed structure is absolutely feasible by current MEMS technology. Mechanical structure consists of two micro-scale arms which together hang a plat. In length of each arms embedded Mosfet transistor placed which on its’ gate plate very thin layer of piezoelectric material, PZT-5A, has been placed. Incident acoustic wave cause mechanical stress which induce surface charge on the interface of piezoelectric and gate layer. These charges will modulate transistor’s channel resistance and finally with employing electronic circuit electric current variation transfers to voltage variation. Simulation results indicated sensitivity of -160 dB in frequencies well below first resonance.

Ultrasonic scissors are used in many emergency surgeries. They have much more advantages than other similar and traditional methods such as producing less smoke than the burning soft tissue and increasing the speed of surgeon during surgery. The purpose of this study is to make an ultrasonic scissor device with the ability to separate the ultrasonic transducer from the main body of the scissors. The importance of separation is that the part of the horn which is in contact with the body tissue can be used as disposable. In this paper, using simulation and finite element analysis, ultrasonic transducer, booster and horn converter design methods are discussed, and then by combining these three parts, ultrasonic scissors are created to split the soft tissue of the body. The heat generated by the active blade of the ultrasonic scissors on the muscle tissue is also simulated and finally the sensitivity of this device is investigated. The obtained results from the simulations in this study are investigated and an ultrasonic scissors at a resonance frequency of 57.1 kHz with a maximum displacement amplitude of 120 μm is fabricated. Limitations such as material of parts, ergonomic design and size, confine the frequency of ultrasonic scissors to small interval and it is obvious that higher frequency, if possible, provides more suitable working conditions.

In this paper, a dual-junction perovskite/CIGS solar cell is designed to use in marine equipment and navigation systems as a renewable energy source. In this design, first, a top solar cell consisting of a perovskite absorber layer with band gap of 1.9 eV is simulated. Then, bottom solar cell is fabricated with a CIGS absorbent layer with a 1.4 eV band gap. Since the perovskite and CIGS band gaps are both adjustable, these two materials can act as a proper partner for an absorbent layer in a dual-junction solar cell. To connect the top and bottom cells, four‐terminal topology is used. In this structure, instead of the usual connection of p-i-n and n-i-p perovskite, n-type and p-type homojunction perovskite connection is used, in which the transfer and separation of carriers are done by an internal electric field. Due to the fact that in this structure, the discharge area is smaller, the recombination of carriers is increased, and the light losses are reduced, which will increase the absorption and efficiency of the cell. The efficiency of the designed dual-junction solar cell is obtained as 30.71%. According to this efficiency and its stability in different environmental conditions, the designed structure can be used in marine equipment and navigation systems as a renewable energy source.

In this article, the characteristics of 1-3 piezocomposites based on PMN-PT relaxor single crystals with different percentages of PT were investigated. For this purpose, parameters of electromechanical coupling coefficient, longitudinal velocity and acoustic characteristic impedance were calculated and analyzed with the help of effective parameters model. It was observed that the change of PT percentage has a significant effect on the mentioned quantities. For example, by changing the percentage of PT, the electromechanical coupling coefficient can be increased to more than 90%. In addition, by using the appropriate amount of volume fraction of single crystals, it is possible to greatly reduce the longitudinal velocity, and therefore the characteristic acoustic impedance, as shown by using PMN-0.33PT single crystal in volume fraction. 0.4, a longitudinal velocity of 3300 m/s and an acoustic characteristic impedance of 1.3 MRayl can be achieved, while the coupling coefficient is close to 90%. According to the obtained results, it was seen that the changes in the functional parameters of 1-3 piezocomposite based on PMN-PT single crystals were not linear in relation to the percentage of PT, and necessarily with the decrease or increase in the percentage of PT, the values of electromechanical coupling coefficient, longitudinal velocity and the characteristic acoustic impedance does not decrease or increase, and the optimal point should be found by examining different percentages of PT according to the desired application.

Science and knowledge along with new technologies have always played a key role in providing defense and national security needs. Quantum technologies are among emerging technologies that use the laws of nature to provide unprecedented capabilities in sensing, imaging, communication, and computing, and because of their dual use, have the potential to reshape the world and spark a new arms race. Quantum technologies for military applications introduce new capabilities, improving effectiveness and increasing precision, thus leading to ‘quantum warfare’, wherein new military strategies, doctrines, policies and ethics should be established. This paper provides a basic overview of quantum technologies under development, also estimating the expected time scale of delivery or the utilization impact. Accordingly, considerable public and private investments have been made around the world to develop these technologies and leave the laboratories and enter the operational stage. Due to the continuous development of technology, the threats posed are also increasingly diverse, and quantum technologies are likely to transform our lives in the next 20 years. In this article, we provide a general introduction about quantum technologies in progress, and we will report the military applications of quantum technology for various defense fields, and finally, we will present a report on the current state of achieving this technology in the world.

Estimating dynamic behavior of high-speed Planing vessels is one of the concerns of designers of such vessels. Evaluation of the loading and center of gravity variation effects, for small vessels with different motion modes, are very important at design stages. Such effects, if not taking into account correctly, may affect the final behavior of the vessel. In this research, for investigating the effects of loading and the center of gravity variations on the behavior of a monohull planing boat, a scaled- down 1:5 model was built based on the ITTC standard and Froude method. after the preparation and balance of the model, tests of the model have been carried out in the high-speed towing tank, in calm water and two loading conditions and at four positions of center of gravity. In each run of test (total 40 tests), the resistance, trim and sinkage, have been measured, and the longitudinal and transverse dynamic stability of the model has been qualitatively evaluated. The results show that increasing the weight will increase the resistance. increasing the distance of the center of gravity position from the stern, will reduce the resistance and trim in the displacement mode and increase the resistance in the planing mode. Also, the decreasing the center of gravity distance from the stern, will reduce the resistance and increase the trim in the planing mode, but may results in the longitudinal instability of the model in some extreme conditions.