فصلنامه علوم و فناوری دریا
سال بیستم شماره 77 (بهار 1395)

Given the important role of satellites in maritime communications, especially in the Global Positioning System (GPS), very high cost of the build and launch a satellite into space is the most important problem. Therefore, for each country or company, the lifetime of satellites is very important. The life of a satellite largely depends on the quality of its construction, but the most important factor that limits is the fuel which is transported. So, it should be considered to the right solution to control fuel consumption and saves it. Bang-bang controller by converting continuous control signal to a pulse train, can provide the ability to save the fuel. If the controller be more time off, the fuel savings will be more. The system is studied in this paper is modeled on European Satellite Moon Orbiter (ESMO) that not only uses the Proportional Integral Derivative (PID) controller for tracking the input pitch angle, but also uses bang-bang controller for reduce the activity of the thruster. The course of this paper is to using Genetic Algorithm (GA) for regulating parameters of mentioned controllers in this satellite. The simulation results indicate that GA has a good performance to optimization of the PID and bang-bang controllers.

Single Point Mooring or contraction SPM is Floating structures that are commonly used in deep water .SPM used for mooring of vessel and transport of oil and gas production from the shore by pipeline to the tanker . The main task of this kind of floating structures, spm mooring should be considered. Properly mooring increase efficiency and ability to perform the task in different environmental conditions for SPM. Floating structures for exposure to harmonic loads such as wave load, should be fatigue analysis. One of the important factors that affect the fatigue is length of mooring line as length of mooring line changes is inversely related to fatigue of mooring line changes. in this paper, SPM with 3-line mooring modeled with ANSYS-AQWA and fatigue analysis of mooring line has been studied in 4 condition of incident wave and 5 condition of length of mooring line.

Ports play a key role in world’s supply chain. With increasing use of container in cargo handling, terminal containers ports are known as the competitive advantage of each port. Among the Iranian ports, the Chabahar port should have an appropriate container terminal due to its geographic position. This study investigated the strengths, weakness, opportunity, and threats associated with the container terminal of Chabahar port using SWOT matrix. Finally, appropriate strategies regarding the results of internal and external evaluation matrix is proposed.
Considering internal and external evaluation matrix (which are 2.364 and 2.584 respectively), status of container operations of Chabahar port is conservative. This status in the SWOT matrix is equivalent to the W-O strategies. Accordingly, solutions such as improving port facilities and concentrating on potential markets are proposed to keep the current condition and to upgrade the status of the terminal.

In the study, spatial and temporal changes in pattern of seawater components in the western part of the southern continental self and deep area of the Caspian Sea were evaluated. The research was based on field data analysis that collected using CTD sensors from sea surface to a depth of 475 m. According to the results, it can be seen that the forming of a deep sound channel in the water column is possible. Vertical distribution of active reaction showed a general reducing trend with depth that reached to 8.2 at depth of 350 m in midsummer. Moreover, observations in November showed active reaction value of 8.3 at 450 m depth. In comparison, amounts of active reaction (pH) in mid-summer (August) were less than that in other seasons. Dissolved oxygen concentrations ranged between 2.0-7.5 mg L-1 at the surface layers. Below level of 100 m, a rapid drop in values of dissolved oxygen were observed and measured about 1.2 mg L-1 at 450 m depth in mid-summer and mid-autumn, while value of 2.0 mg L-1 was recorded below 300 m depth in late winter. The seasonal variations of dissolved oxygen and active reaction (pH) were considerable, especially in intermediate and deepwater layers. According to the obtained data seawater turbidity in winter and spring seasons was recorded more than it in summer and autumn. In most cases due to coastal factors and processes, seawater turbidity of onshore area was more than the offshore.

The growth and survival of aquatics are dependent to environmental condition of water. The goals of this work were to ýfind ýthe relationship between shrimp landing and fish capture with ýdrought in Bushehr province since 2004 to 2011. The air ýtemperature and precipitation data for the ports of Deylam, Bushehr and Dayaer in the in the north, center and south of ýBushehr province, were extracted and analyzed from Meteorological Research Center of Bushehr provinceý. The fisheries ýdata were extracted from Iran Fisheries Organization statistical yearbook of 1997-2011. ý
On the basis of the results, the air temperature is the most important parameter which affects the fisheries stocks. A strong ýnegative correlation was observed between shrimp landing with the average of annual air temperature and average of air ýtemperature during the rainy months of previous year. This imply that ý by increasing the air temperature ýin Bushehr ýprovince, the shrimp capture decreasesý. Due to ýincreasing the world surface temperature and very hot conditions of the ýý2010 El-Nino, the total shrimp ýlanding in Bushehr province was declined from 1431 tons in 2009 to 847 tons in 2010. No ýsignificant correlation was observed between precipitation and shrimp landing. ý
A moderate positive correlation was observed between fisheries capture with the average of annual air temperature and ýaverage of air temperature during the rainy months of previous year. The precipitation has moderate negative correlation ýwith fisheries capture in Bushehr province.ý

The most striking feature of underwater wireless sensor networks is energy constraints and the need to control energy consumption for each node and network.
limited energy of Nodes supplied by the batteries and almost recharge of them is impossible.
Given the importance of energy in these networks, study of parameters influencing the energy consumption of nodes and controling them is useful.
In this paper, the characteristics of acoustic in water is introduced, then by propagation modeling and using the obtained formulas, energy consumption in deep and shallow water in single and multi hopping transmission is compared.

Due to the Limited energy resources in AUVs, their Long missions have been limited. Smarter sensor selection leads to lower energy consumption. Therefore, it can solve the aforementioned problem. Check out all the scenarios is very time consuming. For this reason, the use of heuristic and meta-heuristic methods was considered by industrialists and researchers in the field. ALO is one of the most powerful methods in the optimization problem; therefore, this algorithm by using its unique capability can obtain the best result and the fastest convergence curve among other benchmark methods. As the results show, ALO is very efficient in the sensor selection problem.

In this paper, a new wideband single-layer absorber using frequency selective surfaces (FSS) array is proposed. The proposed structure obtains high stability under variation of angle of incidence until 45° under the normal incidence. . The simulation results show that the fractional bandwidth of 110% is realized for at least 10dB reflectivity reduction illuminated by the normal incidence over the frequency range of 2.16-7.46 GHz. The absorber consists of a copper layer and some lumped resistors. Therefore, the fabrication of the proposed structure is easy and with no resistive sheets

A brief report on "gyrotron tube analysis and design capabilities”, which is developed at "Microwave Tubes Research Center - Shiraz University" is presented. This report covers the interaction region, coupler and power divider and magnetron injection gun parts of gyrotron systems.

In this paper the optical properties of plasmonic nanostructures consisting of three and four gold nanodisk have been investigated. Near- and far-field properties of these nanostructures have been shown using coupled dipole approximation method and simulation. The results show effectiveness and accuracy of our proposed physical model in which the group theory and basic resonance used for modeling of resonance modes.