مجله علوم و فنون دریایی
سال سیزدهم شماره 2 (تابستان 1393)

According to recent advances in military science and electrical engineering on the one hand and on the other hand، subject of replacing diesel engines with electro motors (due to higher efficiency، less maintenance، better performance، better dynamics، etc.)، this paper discuss about electric ships and simulation of the boat drives with electric motors. Since the construction of electro motors up to 1970th (which is the start point of Power Electronic that result in speed control of AC motors)، the propulsion system hadn’t been use system uses electric motors. But after that، due to the high response rate، quick start، high efficiency، good reliability، easy maintenance and low cost… Day by day the use of AC motors became more significant. Since Modeling and Simulation of vector control of AC motor for boat propulsion (with Load model) hasn’t been written as an detailed article، so the purpose of this paper is analyze of vector control performance of induction motor as vessels motor. The Contents of this article is this respect; after Introduction، various components of the propulsion system are discussed that with Load model will give propulsion system of vessel. In this paper after describe of vessel propulsion system، the vessel with electric propulsion motors has been discussed and finally an electric propulsion system for typical vessel is designed. The result of modeling and simulation of this project in conclusion part is discussed.

In order to identify natural and anthropogenic pollution in Gowatr bay (also gowadar bay)، the distribution of heavy metals in the surface and different depths of marine and intertidal sediments was studied. For this purpose، 17 surficial sediment samples، and 5 sediment cores were collected، and compared with local background concentration. The results of surficial distribution of heavy metals indicate that maximum concentration of Copper and Zinc، Lead، and Nickel is related to Pasabandar harbour، sandy coast، and mudflats of Mangrove jungle، respectively. Calculated correlation coefficients between elements and clay fraction indicate a positive correlation between Iron، clay minerals and potentially toxic metals، especially; Cu، Zn، Pb and Ni. Heavy metals distribution at depth was determined in five sediment cores. Sixty percent of sediment cores display surficial Pb enrichment، while Ni and Co are concentrated at depth. According to geo-accumulation factor (Igeo)، zinc and copper show heavy contamination in Pasabandar harbor. Maximum PLI and RI are also related to Pasabandar harbor. Marine traffic، and ship yards activity at and close to Pasabandar harbor and mangrove jungle، along with weathering of ophiolites are apparently responsible for the observed elevated concentration of heavy metals in Gowatr bay.

mudflats of the most important coastal habitats of the Persian Gulf to go and base are essential primary production. Variety of animal species to determine the biological and ecological health of an ecosystem of water is important. Class of ostracoda component of hard skin is shelled. To study the diversity and distribution of this species in the area seven stations were selected Bahrakan tidal beach. Sampling of sediment cores by the core 8/5cm2 from 5 cm surface sediments were performed. Environmental factors such as salinity، temperature، dissolved oxygen and turbidity was measured. Total organic carbon and grain size of total deposits each station respectively. Biological sediments at each station with 10% formalin were fixed، 63 mm sieve، then washed and stained with Rose Bengal and the organisms isolated were tetrachloride carbon. The density of organisms in the winter and summer were 10495 and 3565 individuals in the 10cm2، respectively. Finally، 29 species were identified. Cytheridae family was abundant. The highest value of Shannon’s diversity and brilluin index، Margalef index، Hill and Pielou’s evenness calculated in winter. The highest total organic carbon in winter and summer was 9. 59 and 4. 61، respectively. Sediment grain size showed that the region made of silt – clay and the highest percent of silt_ clay was in summer.

Marine accidents، particularly those that involve pollution and large fatalities، bring into question the safety of shipping and the quality of ships and their crews. Whether or not such questions are justified، it is marine accidents that provide a poor image of the industry، which attract considerable attention. Incidents that particularly attract attention are those causing loss of life، pollution of the environment and the loss of ship and or cargo. Usually، People have a tendency to focus on the consequences of an accident rather than its root causes، Kristiansen S، (2005)، so MCDM could improve to find the root cause elements by providing more precise decision parameters. Due to the complexity of Marine accident investigation، this study aims to provide a systematic approach to determine the degree of most influence parameters (cause and effect) in accident occurrence، in order to improve marine safety in direction of Good Governance; in the study two phase procedures are proposed. The first stage utilizes Fuzzy Delphi Method to obtain the critical factors of the Marine Accident Investigation by interviewing the related connoisseurs. In the second stage، Fuzzy Analytic Hierarchy Process is applied to pair fuzzy numbers as the measurable indices and finally to rank degree of each influence criterion within accident investigation.

In this study، SWAN numerical model used to modeling waves and obtain the significant wave height in range of Amirabad seaport of Caspian Sea. To do this، first، a general model to modeling the wave height in the entire Caspian Sea was built. Then the boundary conditions obtained from the general model، by using the NEST operation of SWAN model، modeling the local with higher magnification in the area Amirabad Seaport was used. The local models built in the Amirabad، was calibration and verification with waves profile data recorded by buoys deployed in that area. Comparison the results with data measured by the Amirabad buoy shows that modeling done in this area had a good accuracy. Then running the SWAN model for three years and Obtained significant wave height in the desired location. Finally the wave energy obtained from significant wave height.

scouring and sedimentation is one of the most important topics in costal that always has been consider for river، coastal and marine structure engineers. Using RipRap is one of the simplest and economical methods for coastal protection that is very common because it is easily available، cheap and simple for construction and low costs. Rip Rap directly and indirectly used for protection of coastal against of erosion. one of the most important topics about is provide a criteria for its design and selection that has been less studied and available investigations are in straight route while due to flow pattern in the bends scouring is sever. The purpose of this study is provide a RipRap design criteria for protection of coastal against scouring. In order to achieve the research objectives، in the laboratory conditions evaluated one riprap size of inch diameter، lengths، distances and angels. The results showed equations for design of riprap and in another part of this study evaluate present equation of other researchers for using in the bends.