As a developing country, Indonesia has been consuming energy with 114 Million Ton Oil Equivalent (MTOE) and estimated that the demand for energy will increase up to 167,4 MTOE in 2050 by Indonesian Energy Ministry. It is also estimated that natural gas will play the role in fulfilling the energy demand in Indonesia. However, in utilizing the natural gas spread of the regions, Indonesia still lack of natural gas infrastructures. As natural gas infrastructures are playing a vital role on those problems, the condition of supply demand, capacity of infrastructure and the effectiveness of the route need to be adjusted and considered. In this study, system dynamic method is employed in order to forecast the supply and demand of natural gas in East Java Province. In addition, a simulation is carried out to optimize and simulate the scenario model of the natural gas infrastructure at certain time-year period. With the constraint and condition given to the system dynamics, a supply-demand condition in East Java area that mainly comes from electrical power generation, industry and household is assessed. Based on developed scenarios, the model is expected to fulfil the needs of natural gas in East Java. The possibility of establishing new LNG terminal in certain location or expanding the capacity of existing facilities are also considered in this study.
Ship maintenance scheduling management integrated with risk evaluation and Life Cycle Cost (LCC) assessment approach is developed in this research. It improves upon existing practices in arranging an optimal maintenance schedule by modeling operational and economical risks. This paper researches maintenance scheduling algorithm with explicitly consider risks associated with some operation problems such as operating schedule, routes, ship position, resources availability, and achievement of reliability-availability-maintainability (RAM) of system. Modeling of components RAM with their failures consequences results risk evaluation. Time value of maintenance cost, replacement cost, earning rate, and penalty cost are also simulated. When the system reaches the lowest level of lower limit reliability, one or more components should be maintained or replaced. Since maintenance task may interrupt the operation, to minimize time-to-maintain all possible events of maintaining other components at the same time will be evaluated together with resources availability. By researching those possibilities, constraining the risk, and based on LCC calculation result, an optimal maintenance scheduling can be then well established.
This paper proposes a simulation-based method to estimate collision risk for a ship operating in a two-lane canal. According to rule 9 of the Colreg-72 navigation rules, in a narrow canal, a vessel shall keep as near to the wall that lies on its starboard side. However, a busy harbor entered through a narrow canal still presents impact hazards. Certain conditions in a two-lane canal, such as a head-on situation in the straight part of the canal during an overtaking maneuver and large curvature of a turning maneuver in the bend part of the canal, could lead to accidents. In the first condition, the ship alters its own course to the port side to overtake another ship in the same lane but the course altered is too large and hits the wall of the canal. In the second condition, the target ship may take an excessively large turn on the bend part of the canal, causing collision with the ship on the opposite lane. Collision risk is represented as the risk of damage to the ship structure and includes the probability of impact accident and severity of structural damage. Predictions of collision probabilities in a two-lane canal have been developed based on a simulation of ship maneuvering using a mathematical maneuvering group (MMG) model and automatic identification system (AIS) data. First, the propeller revolution and rudder angle of the subject ship are simulated to determine safe trajectories in both parts of the canal. Second, impact accidents are simulated for both conditions. The ship’s speed, and current and wind velocity are randomly simulated based on the distribution of the AIS and environment data for the research area. The structural consequences of the impact accident are measured as collision energy losses, based on the external dynamics of ship collision. The research area of the two-lane canal is located at the Madura Strait between the Java and Madura islands in East Java of Indonesia, as shown by the red line in Figure 1. A project for developing a new port and dredging a new two-lane canal to facilitate an increase in the number of ship calls is currently underway in the research area. Figure 1 shows the ships’ trajectories plotted using the AIS data as on January 1, 2011. The trajectories are mostly seen to be coming out of the canal, confirming that it is shallow and needs to be dredged.
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