فصلنامه علوم و فناوری دریا
سال چهاردهم شماره 55 (پاییز 1389)

Whether exploratory or commercially, acoustic fishery benefits are important in finding a school of fish and other aquatics, but using this procedure and state accurate detailed information for the whole specifications of organisms require sufficient information of sound speed changes, course of ray propagation and their rate of absorption and attenuation. This research has considered the quality of sound speed changes towards the depth in terms of physical specifications of Dayer port' s water situated in the northeast of Farsi island and around 50 Km south of Delvar (latitude 28˚,2' north and longitude 50˚,58΄ east), and also has calculated the amount of absorption in these regions. The results have shown that sound speed is constant with depth and temperature decreases within the first 11 meters, but after that it declines. In the 19- meter depth, there is a stronger decrease which is related to the decrease of temperature. It is because of colder current in this region. By investigating sound absorption curves of the area, it is observed that the maximum amount of attenuation is within the depth of 17 to 27m.

Electronic Data Interchange (EDI) is commonly defined as an application-to-application transfer of business documents between computers using industry-defined standards which enable organizations to send and receive business communications more quickly, flexibly, cheaply, and with higher security than conventional communications. With improvements in the quality and affordability of data communications systems, EDI has become more attractive to all types of organizations. Given the global use of shipping documents, such as bills of lading and charterparties, this paper summarizes the background and development of EDI and the benefits obtained from its integration into Iranian shipping industry, with special focus on the Islamic Republic of Iran Shipping Line (IRISL) and Port and Maritime Organization of Iran (PMO) as the major Iranian shipping companies. Also, it proposes the usage of satellite on move system to facilitate the electrical communication, both ashore and aboard.

Tidal energy is a clean, reliable and available energy that exits vastly. Moreover, it can be offered to most of coastal regions and cities. This clean energy can be used in littoral zones worldwide, together with islands and coasts of Iran such as Chabahar. Furthermore, from ecosystem point of view, this energy is useful for increasing coral reefs and also using organic materials in different applications. Via different turbines, tidal kinetic energy is transformed into electric energy. In this article, different methods of acquiring energy from tidal flows, as well as their economic feasibility, are evaluated and compared. In addition, tidal energy was considered in southern coasts of Iran. The results indicate that helical turbines have great efficiency and construction of electrical production station in Persian Gulf is mandatory.

In recent years, in spite of progressing in the ship propulsion system, many problems are required to work in order to gain highest performance. Optimization of propeller system, as the most important and applicable in this type of systems is of special importance. In many vessels, due to their certain conditions design, ducted propeller is used. Genetic algorithm is a powerful method for finding all parameters in a design with multiple objectives. Therefore, considering various aspects of design, we can use this algorithm for designing propellers. In this paper, GA method is applied for two purpose; hydrodynamic efficiency and vibration consideration, for optimized design of ducted propellers by applying Ka-series with nozzle NO.19A. The results from the ducted propeller design are also compared with the results obtained from the B-series propeller design.

Simulation of fluid flow over a square cylinder can be performed in order to understand the physics of the flow over bluff bodies. In the current study, incompressible laminar flow over a confined square cylinder, with variable blockage factor has been simulated numerically, using computational fluid dynamics (CFD). The focus has been on vortex-induced vibration (VIV) of the cylinder. Vorticity-stream function formulation of the governing equation has been used and the equations have been discretized using finite difference method (FDM). Different flow analyses have been conducted based on various Reynolds numbers. The results show that, as the blockage factor increases, the vortex wakes detach from the cylinder at higher Reynolds numbers and therefore, the channel walls have a suppressing effect on vortex-induced vibration. In order to ensure the validity of the developed code, incompressible Couette flow has been modeled using the code, and the results have been compared against the analytical solutions with good agreement.

Numerical modeling is carried out to investigate the spreading pattern of industrial wastewater released from coastal refineries and power plant into the Persian Gulf. The pollutant sources due to the wastewater outfall of the coastal industrial plants are completely considered in the model. The effects of sources are inspected on the adjacent marine environment. The numerical model is developed using finite difference method in two horizontal dimensions in plane. The model is applied in several planes along the depth and the effect of depth variation is considered in a depth integrated manner. The pattern of pollution spreading in the water is accurately investigated in various conditions due to spring and neap tides. The various conditions of wind are also considered in the study including various direction and speed based on the available meteorological data. It was concluded that the locations of wastewater outfall and the discharge, temperature, velocity and direction of outfall jet are appropriate to satisfy all of the environmental rules.

In this paper we have presented a new procedure for sonar image target tracking using PHD filter besides K-means algorithm in high density clutter environment. We have presented K-means as data clustering technique in this paper to estimate the location of targets. Sonar images target tracking is a very good sample of high clutter environment. As can be seen, PHD filter because of its special features can remove clutter and track targets accurately and precisely. PHD filter does not need data association techniques and so can be used in online application where spent time for tracking is very important.