فهرست مطالب سجاد حاجی زاده

Predicting the effect of waves on breakwaters is very important for port design. One of the types of breakwaters that can be installed, moved and reused in different conditions, even in deep waters, is floating breakwaters. But their complex reaction in response to the passing of the wave makes their use suitable for a certain periodicity range. One of the most important and influential issues in the efficiency of a floating breakwater is its geometric shape. In this research, numerical investigation of the effect of floating breakwater section geometry in single and double rows on the wave transmission coefficient in ANSYS-AQWA software for wave periods between 3 and 10 seconds has been investigated. For validation, the results of the present numerical model were compared with the experimental results, which are in good agreement. In the used models, the immersion depth is assumed constant and the proposed geometric sections with different masses and densities were investigated. Based on the results obtained with in the mentioned periods, a geometry with the best efficiency and lower cost has been proposed for related projects.

Today, the issue of calculating the hydrodynamic coefficients of high-speed vessels is getting more attention. There are different methods for this purpose. Among these methods, one can mention strip theory, forced oscillation tests in the towing tank, and numerical simulation. In this research, STAR-CCM+ software utilized the computational fluid dynamics method to simulate the forced oscillation of the vessel. Subsequently, the added mass, damping, and restoring coefficients are computed. Finally, the obtained results have been compared with experimental values, and the accuracy of the current method has been examined.

In the field of port design or protection of marine structures, one of the important things is predicting the performance of breakwaters against radiation waves. A type of breakwater that today, in addition to being able to be quickly installed, moved and reused in areas with similar conditions, maintains the water connection between protected space and open waters, is a floating breakwater. One of the factors influencing the performance of floating breakwaters is the geometrical parameters of the floating breakwater section. In this research, the numerical investigation of the effect of geometrical parameters of rectangular floating breakwater in single-row and double-row state on its hydrodynamic performance and wave transmission coefficient in ANSYS-AQWA software for wave periods in the range of 3 to 7 seconds has been investigated. For verification, the results of the present numerical model were compared with the laboratory results of Ji Deng et al. in (2019), which is in good agreement. The results showed that the use of a rectangular floating breakwater with the ratio of the height of the structure to the width of the structure in the range of 0.35 to 0.45 has the best performance. Also, increasing the mass of the structure against short-period waves improves performance and reduces the forces on the restraining cable and while in the face of long-period waves, reducing the mass of the structure improves the performance of the rectangular floating breakwater.

Planning vessels have a special significance in the marine industry. The main and most significant aspect of designing these types of vessels is achieving high speed by having low body resistance. One of the key modifications applied to the hulls of planning vessels was the development of the chine. This research aims to analyze the impact of the chine on planning hulls using numerical analysis. After analyzing the results, improved chine can be specified in terms of the hydrodynamic performance of the hulls. The chosen method to analyze the flow around the planning hull forms is numerical simulation. This method calculates the resistance force, lift force, pitch angle, and heave amount of the intended hulls. The numerical simulations of different modifications of the C planning hulls were compared to the hydrodynamic behavior of the C-hull after verifying the results of the numerical simulations and validation of results with the laboratory results of the former reference. Based on the results obtained from the numerical simulations, the hull with 5.43% chine width to beam ratio recorded the lowest resistance. The highest trim was observed in the hull with 5.43% chine width to beam ratio, and the hull with 5.87% chine width to beam ratio registered the highest heave. Moreover, the hull with 4.57% chine width to beam ratio exhibited the highest resistance in the simulations.

Since reducing the hydrodynamic resistance of the vessel brings advantages such as reducing fuel consumption at a constant speed or increasing the speed at constant fuel consumption, many designers started to provide designs and changes in the geometry of the vessel in order to reduce the hydrodynamic resistance of the vessel. In order to reduce the hydrodynamic resistance, the viscous and wave resistance should also be reduced. For this purpose, it can be shown that this component of resistance is noticeable in longitudinal Froude numbers higher than 1.76. Today, creating steps in the body is also used to reduce viscose resistance. For this purpose, the Southampton series C-2 double-stepped hull was selected and its efficiency was investigated in calm and rough water. Numerical values in calm and rough water conditions are in good agreement with the experimental results of previous references. In this study, the vessel is simulated at 5 speeds and 2 regular waves. This review was done with the help of StarCCM software.

Floating breakwaters are good alternative to the so-called fixed base breakwaters, which, in addition to having the main purpose of protecting the beach from waves, also maintain the water connection between the sea and the protected area. Researchers in order to increase the efficiency and increase the performance range of floating breakwaters, have done many researches on their effective parameters. In this research, due to improve the performance of the rectangular floating breakwater, the effect of using straight transverse ducts with a rectangular cross-section and transverse ducts with a geometric design modeled after the Tesla valve on the performance of the floating breakwater using ANSYSAQWA software was investigated. In this modeling, floating breakwaters with a height of 4 meters and an immersion depth of 2 meters were analyzed under the influence of waves with a height of 1 meter and in the range of wave periods (3-8) seconds. The results showed that compared to the rectangular floating breakwater model in the period (3-8) seconds, Using a straight channel in the body of a rectangular floating breakwater up to an average value of 20.9% and using a duct with a geometric design modeled on the Tesla valve in the body of a rectangular floating breakwater improves the performance of the structure up to an average of 20.3%.

In recent decades, speedboats have become extremely important and various hull shapes have been proposed, designed and built to achieve high speeds. High-speed vessels are divided into four groups: single-hull, hydrophilic, surface-effect and multi-hull vessels. Here, the main focus is on the wave piercing vessel with spray rail. Speedboats face various challenges to reach the high speeds intended by the designer. V-shaped transverse vessels do not generate hydrodynamic lifting force well. One way to create a hydrodynamic lifting force in fast vessels is to add a spray rail in the longitudinal direction of the hull. When water flows to the side of the float, the water flow is directed downwards using a spray rail, causing a hydrodynamic lifting force. In this dissertation, with the laboratory analysis of the wave piercing vessel, which includes trim, resistance and displacement of the height of the center of gravity (VCG) of vessel, once in calm water conditions with spray rail at a location of 24%T and once without installing spray rail, it has been compared by numerical analysis under exactly the same conditions, which has an acceptable error rate. This optimization, which is done by applying spray rail, significantly reduces trim and resistance at high speeds, as well as increasing center of gravity height changes. This dissertation can be a reliable reference for improving the performance of planning body vessels in the future

Bulbous bow optimization for ship is one of the ways to increase the efficiency of the ship through its hydrodynamic performance. In this study, with the aim of STAR-CCM +, the effects of changes in bulbous bow length for the KCS ship on hydrodynamic behaviour investigated. For this purpose, the leng3th of the bulbous bow was reduced by 5%, and increase 5%, 15% and 25% compared to the baseline, and then simulations were performed on three Froude numbers of 0.22, 0.26 and 0.30. Their results of the simulations show that with reducing the bulbous bow length by 5%, the total resistance in the three Froud number increased, respectively, but increased the bulbous bow length the total resistance reduced. Also, with increasing Froude number, the effect of the bulbous bow length will be more influence in reducing the total resistance.

In this paper, the aim is to analyze the interaction of a commercial container vessel with irregular surface water waves by computational fluid dynamics and also to calculate the marine parameters of this structure, namely the response amplitude (RAO) operator, the kinetic response spectrum in the motion of the structure. Analysis tool in this research is STAR CCM + software based on computational fluid dynamics, which is one of the most powerful software in performing simulation and numerical analysis for the above problem. In this paper, after reviewing and analyzing the validation of the numerical model and analysis tools, the various marine and dynamic parameters for a commercial container vessel in the superficial state in different directions of irregular wave collision to the vessel are investigated.

This study was conducted to examine various studies aimed at socializing via sports participation through a systematic review of the evidence. In this study, all published internal and external papers after 2000 related to socialization through sports participation were analyzed. In the initial search of a total of 10938 research papers in internal and external bases, the articles that were included in the study were evaluated in terms of quality using the checklist, 42 articles were cited and categorized in the context of socialization through sports participation and entered the data analysis stage. The results showed most of the internal studies were centered on Tehran, and foreign studies were conducted with the focus of the United States, Turkey, Netherlands and Romania. The amount of attention to research on socialization has increased in internal papers from 1390 and in foreign articles since 2010. Many researchers have written their article according to the symbolic reciprocal viewpoint, and the largest statistical population of the research was the students. Research results showed that important factors such as family, school institution, systematic propaganda of public and private media, religious institution, government policies, available facilities and economic and social base in sporting system participation have been affected. Finally, it can be concluded that the absence of an appropriate pattern in the context of socialization through sport in internal and external studies is more than ever felt by many social groups that many scholars need to pay attention to this subject matter.

This study was conducted to investigate the role of sports participation in designing and developing a model for the socialization of adolescents. The statistical population included adolescents aged 13 to 11 in eastern Iran who had regular exercise experience (at least three times per week for an hour or more), at least in the last six months, of which 719 adolescents selected as a multi-stage cluster. The tool used in this study was a researcher-made questionnaire designed to collect data, based on the Likert spectrum and with 42 questions. A structural equation model with PLS software used to analyze the research data. The results of this study showed that sports participation had influenced by three factors attitudesmental norms and perceived behavior control. From this point of view, adolescents' attitude toward sport has the most effect on their attendance. The results of the study showed that the higher the participation rate of adolescents in sport, the increased likelihood of them encountering some of the common values in the exercise environment, and it can be easier to pay attention to these values and to create self-adaptation, seeking to increase the level of attention to values Different groups, such as family, friends, and more, subdivide the subjective norms into the conditions for learning these values and, consequently, the transfer of values. As learning and deeper values take place, adolescents are loyal to these values and attract and absorb these values over time and become part of their personal and social identity.

In the last century, with the advent of technology and the need for increased speeds in maritime transport, pay attention to the high-efficiency propulsion systems has increased dramatically. The important note in this regard is that, in order to increase speed discussions about that always have been the focus. One of the related methods is to, design and select the appropriate propulsion system and to select the propeller with remarkable efficiency. In this paper, numerical simulation of a four blade submerged propeller using the computational fluid dynamics method with the help of STAR CCM + software has been performed and the effects of these kinds of propellers on the key parameters of efficiency, torque coefficient and the thrust coefficient is evaluated in terms of the advance ratio and compared with the available experimental results and good agreement between the numerical results and the existing experimental results is observed. The largest difference between the efficiency obtained from the simulation and the experimental results was 15%, which occurred in the advance ratio of 1.4.

The design of ship maneuvers in the early stages of ship design and operation is of great importance. Having a precise model of vessel maneuvers along with the coefficients in the maneuvering equations of ships, is essential for research on maneuverability of vessels, the design of a ship motion control system, and the development of ship maneuvers simulators. Over the past few years, there have been various models of maneuvering ships that can explain ship maneuvers with an appropriate approximation. The design of ship maneuvers in the early stages of ship design and operation is of great importance. Having a precise model of vessel maneuvers along with the coefficients in the maneuvering equations of ships, is essential for research on maneuverability of vessels, the design of a ship motion control system, and the development of ship maneuvers simulators. Over the past few years, there have been various models of maneuvering ships that can explain ship maneuvers with an appropriate approximation.

The aim of this study was to examine the role of personality in employees’ silence and organizational indifference. The statistical population consisted of all employees in Sport and Youth general office of Kerman province and all of them were selected as the sample by census sampling method (n=92). Data were collected by big five personality (Den Eve and Oswald, 2012), employee silence (Brinsfield, 2009) and organizational indifference (Danaei Fard et al., 2009) questionnaires. Pearson correlation coefficient and path analysis were used to analyze the data. The results revealed a significant reverse relationship between conscientiousness, openness to experience and extraversion with silence and organizational indifference. Findings from path analysis showed that personality had a direct effect on employees’ silence and organizational indifference and it indirectly influenced indifference through employees’ silence. Therefore, it can be concluded that those employees with conscientiousness, openness to experience and extraversion personality would not be silent on the problems in the organization and will be sensitive to the future of the organization. Thus, if organizations seek to have the culture of comments, they should consider personality as a part of human resources planning process.

Ship maneuvering in calm water and waves are important topics to avoid collisions and broaching, therefore reliable ship maneuvering simulations are required for incident analysis and prevention. The maneuverability of planing crafts has been the subject of many research projects during the last few decades. To assess the maneuverability of planing crafts at the early design stage, reliable simulation models are required. Traditionally, these tools have used empiric descriptions of the forces and moments on the planing craft’s hull. However, nowadays new numerical modeling techniques are available enabling more reliable predictions of the maneuvering behaviour of planing crafts. Ship maneuvering performance evaluation is essential in primary design stages. Ship maneuvering calculations, horizontal plane motion control and development of maneuvering simulators need a mathematical description of ship maneuvering. In the recent years, different mathematical models are suggested for maneuvering of displacement vessels that are capable of estimation of vessel maneuvers with acceptable precision. But simulation of planing craft maneuverability through mathematical model is not common yet and is the subject of future research. In this paper different maneuvers are executed through the mathematical model. Then the mathematical model is solved and different maneuvers are simulated. Simulations are validated by model tests. Finally the influence of rudder angle on maneuverability of planing ship is studied. Different between simulation results and experimental are lower than ten percentages. At the end of this paper the effect of the rudder dimension on the tactical diameter of planing ship in turning maneuvering is evaluated.

Ship maneuvering performance evaluation is essential for primary design stages. Ship maneuvering calculations، horizontal plane motion control and development of maneuvering simulators need a mathematical description of ship maneuvering. In the recent years، different mathematical models are suggested for maneuvering of displacement vessels that are capable of estimation of vessel maneuvers with acceptable precision. These mathematical models are based on determined hydrodynamic coefficients and their accuracy depends on the known coefficients used to solve the mathematical model. System identification methods are developed to calculate these coefficients utilizing input and output data obtained from different sources. In this paper different maneuvers are executed through free running model tests of a container ship. The hydrodynamic coefficients in the mathematical model are determined by the Extended Kalman filter method. Then the mathematical model is solved and different maneuvers are simulated by coefficients calculated from the experiments. Simulations are validated by model tests. Finally the influence of rudder angle and advance speed on turning circle is studied. The mathematical model and hydrodynamic coefficients presented in this paper can be applied for optimization of ship maneuvering performance and course control purposes.

The purpose of this study was to investigate the relationship between school organizational climate and job involvement of physical education teachers in city of Rasht. The statistical population of this study were consist of physical education teachers in city of Rasht who were comprised of three educational levels (N=200). One hundred and seventy people (85%) participated in this study. The data were collected using the Organizational Climate Description Questionnaire Revision Secondary Schools (OCDQ-RS) with high validity (α= 0.82) and Edwards and Kilpatrick Job Involvement Questionnaire with high validity (α= 0.83). The data was analyzed by using Spearman Correlation Coefficient (p≤0.05). The results indicated that open school climate of primary, guidance, and secondary schools were in middle level. The findings of this study also indicated that organizational climate (R= o.67), and its dimensions of engaged teachers behavior (R= 0.56), intimate teachers behavior (R= 0.66) and supportive managers behavior were positively significant related to teacher job involvement, However, directive managers behavior (R= -0.56) and frustrated teachers behavior were negatively significant related to the teacher job involvement. Therefore it was concluded that, the relationship between behaviors of physical education teachers and supportive behaviors of school managers can effects on their job involvement.