فصلنامه دریا فنون
سال هفتم شماره 2 (پیاپی 20، تابستان 1399)

The state of charge (SOC) estimation of battery in the lithium-ion batteries is of great importance for ensuring its safe operation and preventing it from over-charging or over-discharging. Despite the high importance of the SOC parameter, this parameter cannot be directly measured from battery terminals. So it needs to be estimated. So far, various methods have been introduced for the state of charge estimation of lithium-ion batteries. This paper presents the identification of the battery model and the SOC estimation algorithm for lithium-ion batteries in electric vehicles based on an Fuzzy Adaptive Cubature Kalman Filter (FACKF). In this method, firstly the lithium-ion battery is modeled by a second order RC circuit and then, the Cubature Kalman Filter method is used to estimate the battery parameters and the state of battery charge. One of the requirements of the Cubature Kalman filter is to know the measurement of covariance matrices and process. However, these matrices are generally unknown in practice. In the case of inaccurate selection of Q and R matrices, the performance of the filter is affected and the accuracy of the state of charge estimation is reduced and even divergence may occurs. To solve this problem, in this paper a fuzzy system is designed to monitor the performance of a Cubature Kalman filter. The fuzzy system of R and Q matrices adjusts the filter to have optimal performance. To evaluate the performance of the proposed method, this method is compared with classical methods. The results show the effective performance of the proposed method in comparison with other methods.

The design process, fabrication, and measurement results of a 1 - 3 GHz, balanced power amplifier with an output power of around 160 W are presented. The balanced power amplifier includes two 90W-RF power transistors and two 3dB, hybrids in a balanced configuration. The matching networks of the transistors were designed using the load-pull and source-pull data and also the X-parameter model of the transistor which both are extracted from the transistor's nonlinear compact model. The balanced configuration, not only duplicates the output power but also improves the reflection loss particularly at the input of the amplifier. The measurement results of the fabricated balanced power amplifier showed an output power between 52-53 dBm, a power gain of 9-12.5 dB and a drain efficiency between 34%-50% in the wide frequency band of 1-3 GHz.

A Remotely operated vehicle (ROV) requires a precise navigation system for positioning, path tracking, guidance, and control. Due to the limitation of the global positioning system in the underwater environment, the inertial navigation system is the most important positioning system in an underwater vehicle. In this paper, based on the nonlinear dynamics of the underwater robot to improve the performance of the underwater robot in path tracking, we propose an integrated navigation system based on inertial sensors, compass, and Doppler velocity log. A continuous-time extended Kalman filter was used to combine the sensor data and estimate the robot's position. The simulation results compared to the navigation systems based on linear Kalman filter and discrete-time extended Kalman filter show that the proposed integrated navigation system based on continuous-time extended Kalman filter can estimate the attitude and position of the robot in the control loop with high accuracy

Propeller-induced vibration of a marine vessel is one of the most complex issues of fluid and structure and the interaction between them. In the present article, numerical simulations of fluid flow around the propeller are performed first and the characteristic curves of propeller hydrodynamic performance in open water conditions are plotted for various advance ratios. It is observed that the maximum relative error of numerical simulations relative to experimental data in various advance ratios is about 7%. Then, the numerical vibration simulations of the solid propeller are performed. To achieve the results independently from the computational grid, the modal analysis results for calculating the vibrational natural frequencies for five different computational grids are compared to each other. Three different popular propeller materials i.e. brass, nickel aluminum bronze, and stainless steel are considered, and the results of numerical vibrational simulations such as natural frequencies and vibrational mode shapes using the modal analysis are compared for these propellers. Quantitatively, the magnitudes of natural frequencies for stainless steel and nickel-aluminum bronze propellers are 33% and 14% more than that of the brass propeller, respectively. In other words, brass is the most vulnerable and stainless steel is the most durable propeller material against resonance.

Now a days using catamaran vessel in passenger, military and commercials is increasing.one of the concept design that attracted many researchers is HARTH (high aspect ratio twin hull) vessel. The advantages of this vessel in addition to large deck, this kinds of vessels have good stability and can maintain speeds in harsh seas. However slamming in high waves can create some problems for these kind of vessels. Some different method have used by designers to decrease the impacts of slamming.one of this methods is adding Centre bows in these kind of vessels. Centre bows can decreased the impacts of slamming.one of the more applicable methods to studying the slamming is the drop test.in this research by using this method, we are testing the different Centre bow cross-sections and the acceleration of them are compared. The cross-sections are set in two categories of 1 and 2 from dimensions view.it is recognized that categories 1 have lesser accelerations than categories 2.

In this paper, the dynamic performance of the high-speed planing hull has been studied, and the effects of changing the deadrise angle and the shifting of center of gravity have been investigated in the waves. For this purpose, Zarnick’s strip theory has been used to extract the forces, and also using the MATLAB software program the simulation carried out. In this program, by assuming regular waves collide face to face and dividing the body into equal transverse sections, the hydrodynamic force at each of these sections is calculated, and the dynamic motion of the vessel is extracted by six-degree-of-freedom equations of motion. In order to validate the MATLAB program, first a comparison between the results of the Fridsma experimental test with the results of the present analysis is performed, and then the effects of the deadrise angle and the center of gravity position were investigated. It is shown that with increasing the deadrise angle from 10 to 40 degrees, the range of pitch and heave motions of the boat increase from 0.16 to 0.18 radians and from 0.31 to 0.37 feet respectively. Also, by bringing the center of gravity of the vessel closer to its end, from the center of vessel to 30% of the total length, the range of pitch and heave motions increase from 0.15 to 0.22 radians and from 0.32 to 0.46 feet, respectively. as a result, in more than 30%, it will be occurring the floating imbalance.

In this paper, with regards to the importance of the reliability analysis in the probabilistic assessment of existing offshore platforms, a probabilistic-based computational framework is presented. For reliability analysis of jacket platforms, FORM is used. In this approach, the environmental loads or the structural response in each step of reliability analysis calculated directly. This probabilistic framework is applied for reliability analysis of 3 jacket platforms which are designed, fabricated, and installed in different years. The annual probability of failure is computed in different years of platform service life. Comparison of result demonstrated that due to reducing the performance of the corrosion protection system after the design life of the platform, the amount of probability of failure increased in the parabolic form with the second order. Also, the reliability index for the old designed platform is lower than a platform designed in latest years.

Heavy metals are one of the most important environmental issues, due to their toxicity and resistance. In this study, the concentration of heavy metals (Alomunium, iron, mangenise, chromium, vanadium, nickele, zinc, arsenic, lead, cobalt, and cadmium) in surface sediments of Chabahar Bay was determined by using ICP OES to assess the risk of the metals for aquatic environment. The sampling stations were consisted of Posm, desalination plant, Konarak, Ramin, the entrance of Chabahar Bay and a reference station. The concentration of arsenic in the sediments of sampling area, especially at deeper parts of Ramin and coastal parts of Posm and Konarak, was 2.5 to 3 times ghier than threshold effect level (TEL), except for deeper parts of Posm. The results of this study showed that the concentrations of chromium (except for Ramin 2 and Tss 2), aresenic cadmium and nickel (except for Tiss 2) were 1-2.5, 1-5, 1-4 times higher than their threshold levels and international guidelines (NOAA و ISQGs), respectively. The results of this research showed that the dominant source of heavy metals in the sediments of sampling area was natural; except for cadmium and chromiumwhich originated from anthropogenic sources. However in some stations anthropogenic sources ffected on the concentration of some elements such as arsenic, lead and nickel.

The northern Indian Ocean (Bay of Bengal and Northwest Ocean) is one of the areas under Nedaja mission, one of the areas prone to the formation of tropical cyclons. In this study, we investigated the timing and pattern of forming tropical cyclons in the northern Indian Ocean region using data from the Indian Meteorological Organization from 1990 to 2017. The results showed that the highest number of cyclons occurred in November, June and October, respectively. There were no cyclons in the months of April, August, September, February and March. The frequency distribution graphs of cyclons formed in both the Bay of Bengal and Northwest Ocean regions show two maximum points. The first peak is related to the consecutive months of May and June and the second peak occurs in the months of October, November and December. The lack of intra-tropical convergence zone in the northern ocean causes no tropical cyclons in the area to occur in the summer and winter seasons. Statistical analysis also showed that if a storm occurs at any degree in the first maximum distribution, with 90% probability we will see the formation of a cyclonin the continuation of the first maximum and the second maximum and with 83.3% probability we will see a cyclon formation in the second maximum.. Background preparation using the results of this study can provide significant assistance in tackling tropical cyclons and maritime safety.

Today, minimizing the cost of heat exchangers (HEs) is a major goal for the designer. In this study, a fast and reliable method is used to simulate, optimize design parameters and evaluate heat transfer enhancement and the economic optimization of STHE. Taking into account the importance of STHEs in industrial applications and the complexity in their geometry, the GOA methodology is adopted to obtain an optimal geometric configuration. The GOA is a metaheuristics search algorithm based on the mimics and simulates grasshoppers 'behavior in nature and the grasshoppers ' move to food sources. The total annual cost (TAC) (including the capital investment cost and the total operating cost consumption to overcome the pressure drop) is chosen as the objective function, and the design variables include number of tubes, number of tube passes, length of tubes, the arrangement of tubes, size and percentage of baffle cut, tube diameter, tubular step ratio have been considered. The developed algorithm is applied to two case studies and the results are compared with the original design and other optimization methods available in literature such as Genetic Algorithm (GA), Hybrid Genetic-Particle Swarm Optimization (GA-PSO), Gravitational Search Algorithm (GSA), Falcon Optimization Algorithm (FOA), Artificial Bee Colony (ABC), Bio- geography Based Optimization (BBO), Cuckoo Search Algorithm (CSA) and Firefly Algorithm (FFA). In order to investigate the feasibility of the proposed method, two case studies have been presented that show a significant TAC reduction of up to 30% with respect to traditional designed STHEs.