فصلنامه علوم و فناوری دریا
سال بیست و دوم شماره 87 (پاییز 1397)

target motion analysis problem known as target tracking addresses to estimate target state variables include position and speed. Underwater target tracking is significant importance due to underwater equipment have an ability to stay hidden. In this paper, bearings-only measurement Which is considered one of the most important tracking methods in military applications is used for tracking of the single underwater target. Purpose of this paper is to present novel structure for solving bearings-only tracking problem in the 2D coordinate. This method is based on a combination of fifth-degree cubature Kalman filter and Rauch-Tung-Striebel (RTS) smoother. Proposed structure includes two levels named forward filtering and backward smoothing. Monte Carlo analysis of the Simulation results shows that this structure can be used as an alternative solution for bearings-only underwater target tracking.

Nowadays, the use of graphene and its nano structures has evolved greatly in the electronics and electronics fields. Such structures are found in shapes such as nano ribbons, nano meshes, and quantum dots. Calculating the electronic and optical parameters of these structures is the main concern of the researchers. One of these parameters is their optical conductivity, which is widely used in electronic and telecommunication applications. The sharing of these structures creates a band gap in their energy levels. In this paper, the calculation of an approximate energy-based method for calculating the optical conductivity of nano graphene is presented and simulated using Matlab. With regard to simulation, it can be seen that increasing the energy gap leads to an increase in the optical conductivity of higher wavelengths.

Nowadays the air conditioning systems, are often types of condensing refrigeration systems. In this types, compressor's driving force is supplied by the engine's axial force. So, it has to do more work and consume more fuel. Thus absorption refrigeration systems, have inspired by oil refrigerator's system with the aim of reducing the incoming load on engine, reducing pollutants caused by more fuel consumption and recovering waste heat from exhaust and radiator. This systems can be used in refrigerator. The target was simulating an absorption refrigeration cycle with a higher COP than the similar available ones. In this analysis, an absorption refrigeration cycle was simulated to study the effect of variables on cycle's COP. such as, mass flow rate of returned water from the generator (m ̇_4), mass flow rate of returned water from the rectifier (m ̇_6), fluid's temperature before and after the generator (T_1, T_3) and etc. This sample was simulated in EES with a positive average error of 5.97% of the main sample. The effect of mentioned variables on the refrigerator's COP was investigated, data were collected in the tables and the results were shown in charts. In these charts, the optimal points and optimal operating conditions of the cycle were suggested. According to the analyzes performed, increasing of m ̇_4, decreasing of m ̇_6, decreasing of T_3 and increasing of T_1 , had more effective role in changing the value of the cycle's COP and delivering it to the optimum value.

A piston ring design is greatly influenced by the operating conditions and it affect diesel engine design factors such as fuel consumption, pollution, dissipative forces and overall efficiency of the entire system is affected. Studding of virtual contact is formed by the piston rings and cylinder bush, including the modeling of elements and working condition is the first step. The main topics include the basic functions associated with the piston and piston ring design elements and materials, mechanical loads in the ring, contact pressure between the ring and bush, coefficient of friction, the force of friction, wear and other relevant parameters. To understand the basics of the ring, the mentioned factors were model and developed using ANSYS software. The results included displacement of stress, failure and other important factors that are associated with the materials used and the working conditions that were examined in the subsequent design of the survey will be used.

The calculation of the geostrophic current of the Persian Gulf is examined in this paper. Twenty stations were considered in this study, in different parts of the Persian Gulf being placed on ten transects. Analysis of the data showed that the most appropriate model is the two-tiered model of geostrophic current in the Persian Gulf. The slope of the two-tiered border in the Persian Gulf is stretched along the north-south border and towards the Persian coasts; the direction of the slope changes when it reaches the Strait of Hormuz. Therefore, the geostrophic balance is established in a north-south direction. The results of the measurements corresponded the results of mathematical models for the Persian Gulf. The results presented in this study indicated that the average speed of geostrophic currents in the summer is 0.01 m/s

. The purpose of this research is to find the most important factors affecting port selection and determine the most optimal port using these factors in the main port of the Persian Gulf (Jebel Ali port of Dubai, Shahid Rajaei port of Bandar Abbas, Iran) and the port of Shah Abdul Aziz Dammam, Saudi Arabia.
This research has been done in three stages. In the first step, using the literature review of the subject and collecting expert opinions, using the Delphi technique, the criteria for assessing the ports were gathered. At the next stage, a researcher-made questionnaire was developed, the validity of which was obtained by eight experts and its distribution. Among the experts of port authorities and experts of shipping companies of Shahid Rajaee port weighed the most important factors affecting the selection of ports in the Persian Gulf. In In the third stage, using the results of the second questionnaire and based on the methods A multi-criteria decision making (topsis) with a fuzzy approach attempted to rank the best port in the Persian Gulf region.
The results of this study indicate that Jebel Ali Port (UAE) with the score of 0.730469 ranked first, Shahid Rajaee Port (Islamic Republic of Iran) with the score of 0.552427 and ranked third in the port of King Abdul Aziz (Saudi Arabia) With a score of 0.428903.

Currently, there are no tidal power plants in Iran, although conditions are good for tidal power generation in the southern coasts of the country. Several tidal power plants can be installed in these regions which can provide locally needed electricity or to be fed to local grids. The location selection for tidal power plant is a key strategic decision, which has significant impact on economic operation of the power plant and sustainable development of the region. Further, the location selection is an inherently complex multi-criteria group decision-making problem involving several conflicting criteria on which decision maker’s knowledge is usually vague and imprecise. It is generally hard to find a location that meets all the evaluation criteria simultaneously, so a good compromise solution is preferred. To deal with the problem, this paper proposes a rational and systematic multi-criteria group decision-making method that combines The Compromise Ranking method, also known as the VIKOR method, and fuzzy logic. The applicability of the proposed method is demonstrated by a real-world case study of tidal current power plant location selection in Iran. The alternatives of this study area are Khowr-e Musa Bay, Bushehr Bay, Qeshm Canal, Chahbahar Bay. According to the final score, the first alternative, Khowr-e Musa Bay, is the most suitable location for setting up tidal stream power plant.