International Journal of Coastal, Offshore and Environmental Engineering
Volume:1 Issue: 1, Winter 2016

This research is dedicated to study the relative stress concentration factors (SCF) at FRP strengthened tubular T-joint subjected to brace in-plane and out-of-plane bending moments using Finite Element Analyses performed by ABAQUS software package. Validation analysis for the finite element model of the unstiffened joint is performed against the experimental results together with the Lloyd’s Register and API equations. The effectiveness of using three different types of FRP materials such as Glass/Vinyl ester, Glass/Epoxy (Scotch ply 1002) and Carbon/Epoxy (T300-5208) on enhancing the fatigue life of tubular T-joints through computing the SCFs was investigated in three schemes. At first the chord alone was strengthened in order to investigate the effects of strengthening the chord member on SCFs. In the second phase, FRP was applied only on the brace member to study the brace strengthening effects, and in the third phase, both of the chord and brace members were strengthened. Promising results derived from analysis which show that FRP strengthening method can effectively decrease the SCF values at T-joints.

Developed mooring unit, the MoorMaster, which replaces conventional mooring lines is addressed here. The hydraulics of the system have a strong deducting effects on the motions of the moored ship. MoorMaster act in two different states. In first state; mechanism controls transfer mechanism to suitable position and joint with ship. Second state is passive mechanism state that lock in last position and the controller is passive so that springs and dampers appliance in mechanism carry passively apply forces from ship to mechanism. First; we defined state variables and According to the Lagrange equations, dynamics model of MoorMaster is extracted using Matlab Toolboxes and dynamics numerical simulations will be done. Then design a Controller to control the mechanism to stick to the vessel’s body. Second state; investigate the interaction forces/moments in between the moored ship and the mechanism. have considered the simplest case, where the ship is located just under the MoorMaster force. Ship motion equations solved using Lagrange equations. And then design a controller that gives the ability to MoorMaster which exert forces and torques suitable in the freedom direction, per ship behavior. The results are given in a series of figures.

Offshore pipelines are an efficient long-distance transportation method for oil and gas. These are usually constructed by the use of girth welds, while welds may naturally contain flaws. Hence, it is essential to inspect the fracture response of girth welds in order to check the structural integrity of the pipeline. One of the guidelines that is using wide spread for investigating the fracture response of steel structures is BS 7910 which is based on Engineering Critical Assessment (ECA) method. In this paper Engineering Critical Assessment (ECA) of offshore pipeline girth welds is done according to BS 7910 through Crackwise software and the influence of several parameters on ECA is presented. It is concluded that Influence of misalignment on axial internal surface flaws is more significant than on axial external flaws. Furthermore it is observed that internal surface flaws have always larger values for tolerable defect heights than external surface cracks. In addition, circumferential surface flaws have evermore larger amount of acceptance level in defect heights than axial flaws.

LNG chain value consists of gas exploration, gas liquefaction, transportation, Re-gasification and finally gas distribution to the end user network. Transportation part of this chain normally consists of 25 to 30% of the total vale and is the most lucrative part of it. As proved Iranian gas reserves is about 29 trillions cubic meter and nearly half of it is South PARS gas field shared between Iran and Qatar ,there is an increasing concern on entering into gas export market in near future.
This enthusiasm enquires a thorough financial study on economical feasibility study on this industry. In this study by emphasizing on key parameters of LNG shipping industry like, technical vessel specification distance between exporting and importing terminals, cost of LNG carriers , boil of ratio of vessels, oil and gas future price prediction vessels heeling portions and most importantly the difference between vessel purchase and hiring daily rate of vessels.
We are to model this industry economically and by doing an economical sensitivity analysis on the model some economical indexes are extracted which are of most benefit for countries decision makers.
Two scenarios of purchasing and renting vessel have been investigated and it is shown than in different financial condition and oil and gas market there are at least minimum internal rate of return of 4 to 18% and at last these finding have been demonstrated in a 3D diagram showing net in come oil price (as an important parameters) and rent daily rate of vessels to show the profitability of this industry to the reader.

Oscillating hydrofoils in presence of waves under the free surface as new systems for energy extraction is a hybrid renewable marine energy sources. In this system energy extraction is associated with oscillating hydrofoils operating as biomimetic systems in harmonic waves and currents in coastal regions using active pitch control. Another way of energy exploiting is used by installation of foils under the hull of the ships. Flapping foils located beneath the hull of the ship are investigated as unsteady thrusters, augmenting ship propulsion in rough seas and offering dynamic stabilization. In this system the foil undergoes a combined oscillatory motion in the presence of waves. For the system in the horizontal arrangement, the vertical heaving motion of the hydrofoil is induced by the motion of the ship in waves. The survey shows that exploiting of energy from sea using these techniques can be proposed for Iranian hybrid ships for their propulsion as secondary source of energy. Particularly North part of Persian Gulf has a proper situation for installation and operation as marine energy device in coastal regions.

In this study, the coastal upwelling was investigated along the northern shoreline of the Persian Gulf. For this purpose, the shoreline was divided to 34 segments from northwest to the southeast. the long-term satellite data have been obtained including wind speed components and sea surface temperature (SST). Based on wind speed data, the Ekman transport components (zonal and meridional) were computed for a period of 24 years and with the Ekman transport components, coastal upwelling index were calculated for this period. The annual cycles of coastal upwelling revealed the most intense coastal upwelling at the central areas of north coastal waters, about 27.6 N-28.4 N and 51.1 E -51.6 E, including three peaks in June, November and February. Then, a cross-correlation analysis was employed on the 24-year daily time series to evaluate the effect of coastal upwelling on the SST. The time lag at each of segment was found 3 or 4 days (mostly 4). As expected from upwelling theory, the computed statistically significant cross-correlations coefficients represented that the SST reduces more in the sub-regions (segments) with the more intense coastal upwelling along the northern shoreline of Persian Gulf. So, in this paper, the results of the statistical analysis validated the used data and the results came from computation procedure. All the data processing, computation, analyses, diagrams and plots have been programmed and provided by MATLAB.