فصلنامه علوم و فناوری دریا
سال هجدهم شماره 72 (زمستان 1393)

As for the complex physical properties of sonar targets، classification and distinguish of real targets from the false one is one of the difficult and complex issues for researchers and industrialists of the area. Considering the characteristics of sonar targets، intelligent methods have unique capabilities in categorization of that database. Hence، in recent years the use of neural networks and support vector machine has many applications in this field. Sonar database cannot be separated linearly، as the database has high dimensions in input area. Therefore، this paper aims to classify sonar targets by method called Online Multi-Kernel Classification (OMKC). This method consists of a pool of predetermined kernels that by an algorithm، the selected kernels with predetermined weights will be combined and the weights among them will be updated by another algorithm simultaneously. The results show that this method provides classification accuracy equal to 98. 763% which is better than the classical methods of maximum accuracy of 97. 05%. However، the algorithm execution time increases 0. 1014 second، though for compensating this shortcoming، we use random kernels selection and combination.

Using vision systems and image processing for detecting and tracking objects in the natural environment، we faced with high complexity. The most important of these challenges include: occlusion the target object، color stability، multi-object tracking from monocular vision، noise in images، the complex object and scene brightness changes. In recent years، many efforts have been to improve systems to detect and track objects under different conditions. In this paper، we review the most important research، which are classified according to the type of activity. Also، we show advantages and disadvantages of each mentioned category، and we suggest some ways of stability of these methods.

One of the most important vehicles that used for ashore security is Autonomous underwater vehicles. Underwater vehicles operate depend on their mission and consist in two groups light and heavy. Maneuvered capability in these underwater vehicles is high and they can run away from dangerous lines. Underwater vehicles need to achieve knowledge from their environment to operate intelligent and autonomous. For this goal needs to communication tools between environment and vehicles. Sonars are one of the most popular underwater tools that can be done effective operation by ultrasonic waves. In this research underwater operations and sonar systems by image processing based methods has been simulated to increase maneuver capabilities.

In present work، the spray characterization and mixture formation in MAN B&W L16/24 DI diesel engines are studied by using FIRE CFD Code. In addition، the effect of WAVE، KH-RT and TAB different spray breakup models in prediction of performance and pollutants of diesel engines has been investigated. Finally، the accuracy of each model in comparison with experimental data was reported. Results showed that the WAVE model are the better ability to predict the decomposition of the fuel spray’s droplets and predicts the droplet size produced by penetration and decomposition، correctly. Therefore، it can be used for simulation of spray’s wall impingement at engine’s operating conditions.

Nowadays, the majority of Communication and world trade is carried through sea and the country which is the more dominant in the sea is more powerful. Dominance over the sea can be achieved through the vessels such as ships and submarines that are dividing in two main groups commercial and military ships. There are many similarities and differences between kinds of ships, so expressed various Definitions and divisions from kinds of ships. Till now, many definitions of a ship have been provided and many similarities and differences of various types of the ships have been mentioned as well. In this paper we considered the military and commercial applications of ships and reviewed the definitions of warships that have provided by the Conventions on the Law of the Sea and the laws of some countries. We also considered the physical appearance, how to name and identify these ships, the reasons for their dependence on governments, and the importance of separate warships from non-military ships in international law viewpoint. In addition we mentioned the reasons for more restrictions of warships than merchant ships.

Digital wideband beam forming algorithm has been used to directionally band pass filtering on wideband Space-Time Plane Wave signal in Radio Frequency. In this letter 2-D Infinite Impulse Response filter purposed and do Monte-Carlo simulation with 16 array antenna to compare bit error ratio between that and digital Phased Array Feed. Results are shown better performance for purposed 2-D IIR filter and that''s benefits are lower circuitry complex to FIR filter (order 2 against to order 32) and lower computing complex to digital phased array feed (less number of adder and multiplier) in same result. So that has real time performance and low power consumption.