فصلنامه علوم و فناوری دریا
سال شانزدهم شماره 63 (پاییز 1391)

Nowadays the use of high speed crafts has considerably become spread. Of these crafts, due to their high transversal stability and deck area, twin hulls are very important. Similarly in our country considering martial needs, a great deal of concentration is focused on designing these crafts. Hydrodynamic considerations in designing this type of crafts are very important. Using numerical methods for analyzing matters of high speed crafts’ hydrodynamics has greatly become spread in recent years. So much software is produced based on these methods. The good standing CFX is one of those.In this research after modeling a catamaran with 11 meters length, 2 meters width for each hull, and 1.25 meters draft using the mentioned above software, its motion in still water is simulated. By doing so details of the craft’s motion including drag, lift, and pitch are calculated. The ultimate trim of the craft is one another important parameter that is calculated using the model. Besides stability and convergence of the model after almost 6 seconds, in the speed of 20 meters per second, the ultimate trim of the craft is about 4 degrees that greatly resembles to experimental results.

Launching and docking of ships is one of the important problems in ship design. This problem is considered in initial design and final steps of ship building. In this paper, we describe the important methods of Launching and docking of ships, which is today's available in ship yards. One of these methods is slipway method. This method is very practical and important in between of other methods. We focus and describe calculation of this method. So calculate the necessary calculations of this method for a model ship by paramarine program and present the results of it.

The combatant ship design methodology different with commercial vessel is due to design philosophy. At this concept، the applicable rules and methods or naval ship design was created with final users and research engineers. Todays، the global objective of this concept move to utilize the commercial rules for naval ship design and construction and so many countries that have advanced in naval design and construction technology willpower to be a bencficiary. At this report،this subject requirements and uphill matters curtly presented.

In this research، simplified physical model of the submarine hull have been considered as a cylindrical shell contained ring stiffeners. The submarine identification done in low frequency، so goal the determination frequency response function is in frequency less than 100 Hz. For determination frequency response function must be derived mass matrix، stiffness matrix، and damping matrix of model of the submarine hull. For the extraction three matrixes explained، the structure model is in ANSYS11 software، and mesh is with triangular element. Displacement domain of each node considered in radial and axial direction، number of structural elements and nodes coordinates by MATLAB software is finite element analysis theory of rotating shell. Three matrix be derive، then result is natural frequency of submarine hull، and then figure of frequency response function drawing in range of frequency less 100 Hz. Of the success of using this method that is being investigated by the department of mechanics can be note to determine frequency response function of propeller-shafting system of submarine hull، coupling propeller-shafting system to submarine hull، the optimization of resonance changer in low frequencies due to reduction of transmission noise of propeller to submarine hull with technique Genetic Algorithms، description of the acoustic signature of submarine due to submarine propeller excitation. And this method can be considered one of maritime new technologies، and as applicable plan implement in the Islamic Republic of Iran Navy and marine industry.

Pressure hull of the submarines are designed based on the classification society rules and regulations. GL is one of the classification societies which has published a complete set of the rules related to design of submarines. Using this set of rules and optimization can lead to a light weight structure with sufficient strength. Therefore، in this paper the cylindrical shell of submarines with different nominal depth are designed. This procedure includes a optimization problem with nonlinear constraints and objective function. The design variables are pressure hull thickness، stiffeners span، stiffeners web thickness and height and stiffeners flange thickness and width. The constraints are derived from GL Rules to ensure the strength of the shell. The objective function is the weight of the cylindrical shell per unit length.

Today in world based on stability، hydrodynamic characteristics، radar cross section and electronic war systems، focused on novel naval vessels and done a lot of serious research activities. Novel naval ships contain mono-hull and multi hull that is selected based on productivity، cost and mission requirement. According to Mission of the Islamic Republic of Iran Navy and its strategy is needed to allow for future mission needs to be selected suitable naval ships. The selection should be based on knowledge of the other coastal states and other countries in the region. In this paper generally suitable hull in the military''s future fleet has been selected.

Private capital formation has an important role in economic growth. Subject to invest in Iran because of high price volatility and risk is associated with many problems because of investment in different sectors of the economy is strong fluctuations. Given the importance of the impact of inflation on investment, private investment in Iran for the period 1369 till 1390 using quarterly data is investigate. This study tests the Augmented Dicky Fuller (ADF), Phillips Peron (PP) and KPSS test for Stationary variables and to test the assumptions of OLS regression models and also to investigate the structural failure of the tests and Zivot and Andrews and Lamzyn and Papl has been used. Results of hypothesis tests indicate that inflation has a negative effect on private investment in Iran.