مجله علوم و فنون دریایی
سال نوزدهم شماره 1 (بهار 1399)

The main purpose of satellite image processing is preparing thematic and efficient maps, so choosing appropriate classification algorithm has important role in this case. In parametric methods such as maximum likelihood main problem is their dependence on the statistical distribution of input data. Artificial neural network is nonparametric classification method which is not dependent on any particular distribution and extract desired functions from within data. This study aimed to compare the efficiency of neural network and maximum likelihood to classify land cover Using Landsat Satellite Images. Determine classes and samples to classify land cover Using field operations, topographic maps, aerial photographs and maps were made and using the above information four classes vegetation cover, building, water and outdoor were selected. After applying two algorithms, the neural network and maximum likelihood on the Landsat 8 satellite image with OLI sensors, land cover map of the arvand coastal area was prepared. Multi-layer perceptron network neural network structure consists of three input neurons, seven intermediate neurons, and four output neurons. For network training, a back propagation algorithm has been used. with Kappa coefficient, the accuracy of the classification methods was evaluated. Based on the results, Artificial neural network method with kappa coefficient of 0.92 in comparison to maximum probability algorithm with kappa coefficient of 0.79 has a better performance in providing land cover map of the arvand coastal area which is due to Neural network is nonparametric and nonlinear.

In this study, the effects of dietary protein and lipid levels were designed on blood and muscle biochemical composition of Sobaity seabream juveniles (Sparidentex hasta). The six treatments were examined including three dietary protein levels (35, 40 and 45%) and two dietary lipid levels (7 and 14%) with three triplicates. Fish with mean initial weight 36.55±0.28 g were randomly stocked in eighteen 300 l polyethylene tanks and were fed thrice daily to satiation for 56 days. According to the results, at the 14% dietary lipid level, plasma total protein index increased significantly (P

With growth of Technology, With growth of technology, the needs for data and information security over communication channels are necessary. Providing information security in marine environment includes communication between ships and also ships with ground station are one of the most important issues in information security. In order to provide Confidentiality, symmetric key cryptography algorithms such DES, 3DES, IDEA, RC6, Serpent and AES are presented by researchers. Different reports in literature are presented by researchers in order to compare the performance of these algorithms. Despite various considerations, the needs for deep comparison of these algorithms are needed. Therefore in this paper, deep consideration and comparison in the points of architecture, flexibility, security and speed of these algorithms are done. Based on the achieved results, the appropriate algorithm can be employed based on required flexibility, speed or desired levels of security. The result of implementation and comparison shows the advantages of AES algorithm in provided security and RC6 in speed of execution.

In this research, reactive power compensation in the ship is considered as an auxiliary factor for improving generator conditions and improving the ship efficiency in terms of fuel consumption and emissions. To accomplish this purpose, a simplified electrical network is modeled for an all-electric military marine vessel, including propulsion load, distribution loads, sensors, emergency loads and pulse loads (rail guns, aircraft launchers, etc.) Among these loads, pulsed loads have a more damaging effect on the voltage profile of power quality in the ship distribution system. Such loads often require high energy over a short period of time, which mainly causes problems in system power quality and in some cases leads to the destruction of the entire electrical system.In the following, the compensation effect of static capacitors is investigated on voltage profile improvement of a navy ship during a pulse load. The obtained result show that using their kind of compensating has a great impact on decreasing voltage sag and, on the other hand, the speed and torque curves of the propulsion motors will be more stable. All simulation is done in Matlab/Simulink environment and for various situation (different pulse load and static capacitors). Suggested method is robust and improve the parameters of power quality in all proposed scenarios.

In past few years two-dimensional theories in numerical, analytical and experimental solution have contributed in seakeeping and maneuverability of vessels specially planing crafts. Analysis of wedge water entry as a basic problem has wide application. Till now much research in different methods has been done on the symmetric and asymmetric of wedge water entry. in this study wedge water entry with transverse velocity (or oblique water entry) will be studied. Model testing is a powerful means to deal with the said problem, in this study oblique water entry of wedge has been conducted. In this regard for oblique water entry of wedge a setup has been designed and fabricated. using by the fabricated setup a set of oblique water entry tests on wedge of 40 degree deadrise angle in different vertical and transverse velocity are examined and the pressure distribution on the plates of wedge due to impact of water are recorded. The results are illustrated the importance of transverse velocity on the pressure distribution and magnitude of vertical and transverse forces on the wedge. The pressure distribution due to oblique water entry on left and right side of the wedge are not symmetry; owing to increasing of transverse velocity the difference pressure on two sides of wedge is increased, so the transverse force is increased and the vertical force is decreased.

As compared to other transportation modes, maritime transportation is economically cost-effective. Presently, with the existing traffic congestion of coastal ports and in order to promote maritime transportation, dry ports are the best option. This study attempts to investigate and recommend the effective strategies for operationalising dry ports in Iran through SWOT model. The research has used the Delphi method for survey and analyses. Questionnaires were used as the main instrument for data collection and measurement of variables in this research. The research target population was assumed unlimited and the number of sample was found to be 96. First, internal and external factors affecting the operation of dry ports were identified, and then factors were prioritised to determine their position in SWOT matrix by using SWOT analysis. According to the weights obtained from internal and external factors evaluation matrix, growth strategy was suggested for the operation of dry ports.

Superior marine power, on the one hand, changes in the volume and type of maritime missions, the availability of a lean-agile supply chain is very essential in the uncertainty environment. In this paper the Leagility factors of the maritime supply chain has been considered. Using a combined approach of fuzzy cognitive maps and Delphi method, the relationship and ratio of relations of the leagility factors have been identified and the he interaction of these factors were determined. Two main relationship have been found. The leagility factors of the maritime supply chain with high power relationship have dynamic and strong effects on the supply chain leagility, but the Leagility factors of the maritime supply chain with low power relationship have strong effects on leagility readiness of the supply chain.

Generally, determination of degree of coastal area environmental sensitivity is a prerequisite for assessing vulnerability of sensitive ecosystems in these areas, especially mangroves, and plays an important role in the efficiency and success of their recovery and sustainable management programs. Therefore, the aim of this study was also to determine the degree and prioritization of environmental sensitivity of mangroves of Hormozgan province. To this end, using set of criteria developed by the Marine Environment Bureau and review of studies on sensitivity of mangroves, a list of the most important criteria and sub-criteria for the sensitivity of these ecosystems was provided and the relative weight of the criteria was calculated by analyzing the opinions of experts through the implementation of the FAHP method. The results showed that according to expert's opinion, among the nine criteria for determining the degree of sensitivity of mangroves, vegetation cover and recreational significance criteria obtained the highest and lowest relative weight among the considered criteria, respectively (with relative weights equal to 0.23 and 0.03, respectively). The results also showed that the vegetation cover, wildlife and food network criteria with relative weights of 0.23, 0.17 and 0.13, were the most important sensitivity criteria of mangroves in the final rankings. The results of this study by prioritizing the environmental sensitivity criteria of mangroves of Hormozgan province, provides essential information for assessing the vulnerability of these habitats.

Environmental pollution imposes serious hazards and problems to the living organisms. This study aimed to determine the concentration and seasonal alteration of di-(2-ethylhexyl) phthalate (DEHP) and di-n-butyl phthalate (DnBP) in the surface water of Chabahar Bay. Four replicated water samples were taken from the surface layers of seven stations in Chabahar Bay and prepared by dispersive liquid–liquid microextraction (DLLME) method, before being injected into the Gas Chromatography with flame ionization detector. In this method, 0.5 ml of methanol (as diffusion solvent) and 20 µl of carbon tetrachloride (as extraction solvent) were injected quickly into the sea water samples, and after extraction, the deposited phase was taken by a Hamilton syringe and injected into the GC equipment for measurement. Under the optimum extraction and experimental conditions, the method yields a linear calibration curve in the concentration range from 10 to 600 µg/L for target analytes. The enrichment factors for DEHP and DnBP were 775 and 790, the correlation factor 0.997 and 0.997, the limits of detection were 0.04 and 1.78 µg/L and the relative standard deviations of DEHP and DnBP were 0.0036 and 0.058, respectively.The results revealed that the concentration of DEHP and DnBP differ considerably at different stations. Significant differences were also observed between the concentration of DEHP and DnBP at various stations (P ≤ 0.05).