فصلنامه علوم و فناوری دریا
سال هجدهم شماره 69 (بهار 1393)

Erosion control in coastal areas, is imperative.Lian coastal area near the Bushehr nuclear power plant, which has a beautiful natural landscape, is being destroyed.The aim of this study is to evaluate the performance of groyn structures in the area.Using software MIKE21, Lian Shoreline is modeled. Trial and error method, groyn structures with different lengths in different areas of the site have been placed and sedimentation and erosion has been studied in each case.The results of this study indicate that the use of the groyn protecting the coastal beaches, if not done with careful study, can cause detrimental effects on downstream structures.The location of the groyn and the shoreline motion and position relative to each other, will affect on sedimentation and erosion and it’s volume.Modeling helps to choose the appropriate structures and it’s location for the site depending onareausage. For example, in point x=150 of the coastal line, after placing two groyn with length of 500 m, approximately 120 m of erosion will occur after 20 years.Although increasing the length of the breakwater to 850 meters, the erosion rate in this point reaches 23 meters. In point x=85 of the coastal line, after placing two groyn with length of 500 m, we have almost 275 meters deposition after 20 years. Although increasing the length of the breakwater to 850 meters, deposition will be 285 meters.

Information of the enemy's military and security affairs is always one of the important parameters which is considering for defense. One of the most important sources of information is intrusion to computer networks and data base of defense system. Hence, these networks are under constant cyberattacks of enemies. Therefore their protection is vital. Nowadays the use of intrusion detection systems to protect systems has been increased significantly. One branch of computer network intrusion detection is anomaly detection methods in data network. In order to detect the network intrusion, these methods compare the observed condition with the normal one to distinguish the differences in the incidence of acute attacks. Behavioral and relationship status, number of regular subscribers and their typical applications and routine hardware and software relations are of these kinds. In this paper, the Local Outlier Factor as one of the methods based on machine learning used for network intrusion detection, has been introduced.

Unique features and the possibility of easy dissemination of acoustic signals in underwater environment provide the ability to identify and track the underwater targets. From defensive applications of acoustic signals in the sea domain, the following can be named: use of sonar for diver detection in order to prevent the diver’s entrance to harbor equipment plants, protection from the coastal power and so on…. Correct detection of diver from other underwater targets such as: dolphins and fish populations, is important for this purpose. In this paper, we took advantage of two features: target strength and speed of target for diver detection by using support vector machine classification method. The simulation results show that the accuracy of diver detection in this method greatly improved toward the state that only target strength is used for identify.

In this article we have tried to stealth missile and radar equipment from other radars. X band electromagnetic waves in the plasma layer and blades that are magnetic and nonmagnetic in successive reflections are considered. power absorbed, transmitted and reflected are studied with Snell-Descartes method for different conditions. by considering the potential repercussions consecutive losses through reflection and how it is calculated, and the variation of the angle of incidence, external magnetic field, the frequency of the incoming electromagnetic wave and plasma layer thickness and other parameters are drawn blade. Finally, the results and the optimum conditions for various applications are discussed and recommendations.

This paper has studied the models of ship routing and scheduling in maritime transport. The purpose of this research is to identify factors influencing the design of mathematical models of ship routing and scheduling (objective function, constraints and decision variables). These factors include the main fleet, ports and cargo, ship subplot length and width, fleet capacity, routes of transportation, bulk cargo, and so on. According to these factors models are designed for routing, as well as technical and physical obstacles and problems to be solved in the field of ship routing and scheduling.

The request for ships and vessels with higher efficiency, higher speed, less weight and also less cost, by shipyard industry, is highly depended on structural design. The vibration of structures, as one of the related phenomena to the structure of a ship, cause to fatigue in components and decreasing their efficiency. As the vibration will cause to destroying effects, studying the vibration of the ships is a critical affair. It is possible to optimize the place of equipment of a ship by knowing the natural frequencies of that ship. In this study, the modal analysis is done on a high speed craft that is designed based on the ABS rule, by using MAESTRO software and finite element method. One of the other analysis is done in this study, is the effect of engine room location of craft on global natural frequencies., that will be done by changing in engines, and generators placements in defined areas. Finally, due to the validation of the study, the experimental results of the model will be compared with the numerical results which are calculated by MAESTRO software in the vibration lab.