The WEC mooring system is needed to withstand the environmental loadings and to limit the excursi... more The WEC mooring system is needed to withstand the environmental loadings and to limit the excursion of the floating structure without affecting the power production efficiency. MDD type WEC is designed to have device resonant period match to mooring system at the wave frequency (WF). A coupled time domain analysis has to be used to analyze the influence of mooring line to the WEC motions. A literature review on the methods used to estimate the mooring line damping for WEC has been conducted. It is found that finite element method is can be used to model the nonlinearities of mooring line better than quasi-static method.
The effect of the mooring line force of a typical semi-submersible with square column under regul... more The effect of the mooring line force of a typical semi-submersible with square column under regular sea waves for wave heading condition is reported in this paper. A 1:81 scale model of 58748 M.Tonne moored semi-submersible was tested in Marine Technology Towing Tank of Universiti Teknologi Malaysia with 120 m in length, 4 m in width and 2.5 m in depth for the wave frequency from 0.4297 Hz to 1.7189 Hz in steps of 0.1433 Hz. In the tests, model was moored horizontally that are attached to the structure above the water surface level in the head sea with four linear springs forward and aft. Such a system does not have practical usage but is used to study the loading and response of the semi-submersible in the absence of the catenary mooring lines The force or tensions on the mooring lines was measured by load cells. The force measured by the load cells were analyzed to obtain the behavior of the mooring lines force at every frequency step. From the analysis of the experimental results, it is found that among the forward and aft mooring lines, the tension in forward mooring lines is 2 to 4 times more than the tension in aft mooring lines. The mooring forces are not equally shared by forward and aft mooring lines. It also showed that the behavior of all mooring lines forces at each column have a similar trend along the frequency.
Straits of Melaka and straits of Singapore are one of the most congregated seaways in the world. ... more Straits of Melaka and straits of Singapore are one of the most congregated seaways in the world. These seaways are the main connection for the ships travel between western part and eastern part of the world. From statistical record, there were approximately 1500 vessels passing through the straits of Melaka and straits of Singapore daily. Ship to ship collision occurs frequently at these areas due to large amount of ships movement. To assess the risk of ship collision on the Straits of Melaka and Straits of Singapore, an AIS receiver station was setup by local researchers with the fund and support from Ocean and Aerospace Research Institute, Indonesia (OCARI). A computer software is also developed to decode the AIS signal received and to assess the risk profile of the traffic using Pedersen Method (1995). This self-developed decoder and analysis software is built under the assistance and guidance from Centre of Marine Technology and Engineering, Por-tugal (CENTEC). To obtain the ris...
This paper reviews on application of quasi continuous vortex lattice method for determining the p... more This paper reviews on application of quasi continuous vortex lattice method for determining the performance of helicopter tail rotor propeller. Tail rotor blade for Bell B206 of one seat helicopter is used. The method is developed to be suitable for analyzing the performance of propeller in term of thrust, torque, and efficiency. These parameters are calculated based on pressure on blade.
Container terminal capacity should be periodically reviewed. It has to be audited against demand ... more Container terminal capacity should be periodically reviewed. It has to be audited against demand and current performance. A system that allows quick capacity audit is required so that terminal managers are promptly informed of their terminal capacity usage. A quick audit system based on a simple yet effective approach is advantages since an extensive audit exercise is costly and time consuming. This paper presents a quick capacity audit system based on fuzzy expert system approach. The audit system was model based on capacity planning ideas extracted from UNCTAD (1985) and Thomas (1987). CLIPS expert system shell has been used and the logic was developed using fuzzy approach so that it mimics human mode of reasoning and approximation.
The development of high performance materials made from natural resources is increasing worldwide... more The development of high performance materials made from natural resources is increasing worldwide. The interest in natural fiber reinforced polymer composite materials is rapidly growing both in terms of their industrial applications and fundamental research. They are renewable, cheap, completely or partially recyclable, and biodegradable. The coconut fiber can be a potential candidate to replace the industrial core and foam which its application are worldwide and it is used to increase the thickness of the fiberglass boat. In this research, three types of testing panel are constructed by using 10 mm of Coconut Fiber, 3D Core Foam and Infusion Grooved PVC Foam as the sandwich core. The resin infusion method which is produce quality final products have been used. The findings be obtained by conducting two testing methods, for the Flatwise Tensile Strength testing, the specimens taken from Coconut Fiber product yielded a higher value of strength which is 3.005 MPa compared to the specimens taken from Infusion Grooved PVC Foam and 3D Core Foam which is 2.963 MPa and 1.264 MPa respectively. For the Flatwise Compressive Strength testing, the specimens taken from the Coconut Fiber product had higher value of compressive stress compared to the value of specimens taken from Infusion Grooved PVC Foam and 3D Core Foam which is 29.66 MPa, 2.58 MPa and 4.68 MPa respectively. This research has proved that the Coconut Fiber is quite suitable to become as one of the laminating schedule for the construction of the fiberglass boat hull.
Oil and gas production in subsea operation continues to the extreme depth. Harsh environment and ... more Oil and gas production in subsea operation continues to the extreme depth. Harsh environment and severe operation of oil and gas transportation due to high pressure and temperature become crucial for pipeline transportation. Consequently, The pipelines will deform to buckle shape which affect to integrity of pipeline. This phenomenon should be considered in design of pipeline to provide reliability of pipeline operation during time life period. The design result of pipelines is according to DNV F 101 whereas the magnitude of pipeline curvature will validate by ANSYS 14 to ensure pipeline reliability.
This research is targeted to improve the accuracy of diffraction potential theory to predict semi... more This research is targeted to improve the accuracy of diffraction potential theory to predict semi-submersible heave motion response by considering the drag effect in the prediction. From both the numerical and experimental studies, it can be observed that the diffraction potential theory is not predicting well the semi-submersible heave motion response when the motion is dominated by damping. In this research, the viscous damping correction method and Morison equation drag correction method are applied to improve the motion response predicted by diffraction potential theory. This paper will briefly present the procedure to integrate the viscous damping correction method or Morison equation drag term correction method with the diffraction potential theory. The proposed numerical methods are applied in this research to simulate the semi-submersible heave motion response. After that, all simulation results are compared to the experimental result from tests at the same wave condition to validate the proposed numerical methods. From the comparison, it is concluded that Morison equation drag correction method is able to estimate the semi-submersible heave response in the damping dominated region and provides more reasonable motion tendency compare to other methods
ABSTRACT The wave run up under semi-submersible platform deck and the dynamic response are import... more ABSTRACT The wave run up under semi-submersible platform deck and the dynamic response are important design factors, and determine the expected minimum air gap in extreme design conditions. For a semi-submersible, the prediction of probabilities wave run up in harsh environments is a challenging task. This paper addresses the problem of expressing the probability density and cumulative distribution functions that utilize Weibull distribution to model estimates the waves run up for a large volume semi-submersible squared-section columns platform in two sea states. The two parameters Weibull distribution, namely shape parameter and scale parameter were considered. The analysis interpreted the measured data of 9 realizations with different seeds in the moored model experiments. The length of total measured data analyzed included approximately 9 times 250 waves for each sea state. The wave run up was found by model estimates using a Rayleigh distribution, and some waves run up were identical apart from one another for different seeds. Finally, by this model with a sequence return for two sea states the associated motions distribution for the large volume semi-submersible platform were numerically predicted.
The Ocean Thermal Energy Conversion (OTEC) is renewable energy to supply electrical power by usin... more The Ocean Thermal Energy Conversion (OTEC) is renewable energy to supply electrical power by using different ocean temperature between seawater surfaces to a certain water depth. In the OTEC construction, Cold Water Pipe (CWP) is challenging component of OTEC that installed into water depth of >500 m. In this paper the material of CWP is selected the HDPE (High Density Polyethylene), which based on material properties. For commercial scale recently, assembling of joint HDPE pipe uses fusion welding for maximum diameter of 1.6 m. To consider this issue, this paper aims to design the CWP joint using Friction Stir Welding (FSW), which pipe diameter of >12 m. The framework design was performed to short fiber HDPE composite joint process with FSW process. In order to obtain high quality of HDPE joint, optimization of FSW parameters would be highly consideration in joint process. Therefore, this paper revealed a framework design for joint the HDPE pipe in CWP using FSW technique. The proposed framework might provide advantages in technical, investment and time for the FSW process compare to other method of joint process.
Ocean Thermal Energy Conversion (OTEC) is a process that can produce electricity by using the tem... more Ocean Thermal Energy Conversion (OTEC) is a process that can produce electricity by using the temperature difference between deep cold around 28 degree Celsius ocean water and warm tropical surface waters around 6 degree Celsius. Malaysia, Indonesia and the Philippines are located on the equator region which has high potential to implement renewable OTEC technology. Indonesia has many potential locations to build OTEC, among them is in Sumatera Utara, Bali, Flores Sea, Makassar Strait. The OTEC is planned under General Plan of National Energy. The 11th Malaysia Plan (2016-2020) aims to manage the 1st Public-Funded OTEC project of Pulau Layang-Layang, Kuala Baram, Gemusut Kakap, and Pulau Bangi. Philippines as located at geographical position near the equator had passed the Renewable Energy Act of 2008 for OTEC project at Pangasinan, Zambales and Quezon.
The WEC mooring system is needed to withstand the environmental loadings and to limit the excursi... more The WEC mooring system is needed to withstand the environmental loadings and to limit the excursion of the floating structure without affecting the power production efficiency. MDD type WEC is designed to have device resonant period match to mooring system at the wave frequency (WF). A coupled time domain analysis has to be used to analyze the influence of mooring line to the WEC motions. A literature review on the methods used to estimate the mooring line damping for WEC has been conducted. It is found that finite element method is can be used to model the nonlinearities of mooring line better than quasi-static method.
The effect of the mooring line force of a typical semi-submersible with square column under regul... more The effect of the mooring line force of a typical semi-submersible with square column under regular sea waves for wave heading condition is reported in this paper. A 1:81 scale model of 58748 M.Tonne moored semi-submersible was tested in Marine Technology Towing Tank of Universiti Teknologi Malaysia with 120 m in length, 4 m in width and 2.5 m in depth for the wave frequency from 0.4297 Hz to 1.7189 Hz in steps of 0.1433 Hz. In the tests, model was moored horizontally that are attached to the structure above the water surface level in the head sea with four linear springs forward and aft. Such a system does not have practical usage but is used to study the loading and response of the semi-submersible in the absence of the catenary mooring lines The force or tensions on the mooring lines was measured by load cells. The force measured by the load cells were analyzed to obtain the behavior of the mooring lines force at every frequency step. From the analysis of the experimental results, it is found that among the forward and aft mooring lines, the tension in forward mooring lines is 2 to 4 times more than the tension in aft mooring lines. The mooring forces are not equally shared by forward and aft mooring lines. It also showed that the behavior of all mooring lines forces at each column have a similar trend along the frequency.
Straits of Melaka and straits of Singapore are one of the most congregated seaways in the world. ... more Straits of Melaka and straits of Singapore are one of the most congregated seaways in the world. These seaways are the main connection for the ships travel between western part and eastern part of the world. From statistical record, there were approximately 1500 vessels passing through the straits of Melaka and straits of Singapore daily. Ship to ship collision occurs frequently at these areas due to large amount of ships movement. To assess the risk of ship collision on the Straits of Melaka and Straits of Singapore, an AIS receiver station was setup by local researchers with the fund and support from Ocean and Aerospace Research Institute, Indonesia (OCARI). A computer software is also developed to decode the AIS signal received and to assess the risk profile of the traffic using Pedersen Method (1995). This self-developed decoder and analysis software is built under the assistance and guidance from Centre of Marine Technology and Engineering, Por-tugal (CENTEC). To obtain the ris...
This paper reviews on application of quasi continuous vortex lattice method for determining the p... more This paper reviews on application of quasi continuous vortex lattice method for determining the performance of helicopter tail rotor propeller. Tail rotor blade for Bell B206 of one seat helicopter is used. The method is developed to be suitable for analyzing the performance of propeller in term of thrust, torque, and efficiency. These parameters are calculated based on pressure on blade.
Container terminal capacity should be periodically reviewed. It has to be audited against demand ... more Container terminal capacity should be periodically reviewed. It has to be audited against demand and current performance. A system that allows quick capacity audit is required so that terminal managers are promptly informed of their terminal capacity usage. A quick audit system based on a simple yet effective approach is advantages since an extensive audit exercise is costly and time consuming. This paper presents a quick capacity audit system based on fuzzy expert system approach. The audit system was model based on capacity planning ideas extracted from UNCTAD (1985) and Thomas (1987). CLIPS expert system shell has been used and the logic was developed using fuzzy approach so that it mimics human mode of reasoning and approximation.
The development of high performance materials made from natural resources is increasing worldwide... more The development of high performance materials made from natural resources is increasing worldwide. The interest in natural fiber reinforced polymer composite materials is rapidly growing both in terms of their industrial applications and fundamental research. They are renewable, cheap, completely or partially recyclable, and biodegradable. The coconut fiber can be a potential candidate to replace the industrial core and foam which its application are worldwide and it is used to increase the thickness of the fiberglass boat. In this research, three types of testing panel are constructed by using 10 mm of Coconut Fiber, 3D Core Foam and Infusion Grooved PVC Foam as the sandwich core. The resin infusion method which is produce quality final products have been used. The findings be obtained by conducting two testing methods, for the Flatwise Tensile Strength testing, the specimens taken from Coconut Fiber product yielded a higher value of strength which is 3.005 MPa compared to the specimens taken from Infusion Grooved PVC Foam and 3D Core Foam which is 2.963 MPa and 1.264 MPa respectively. For the Flatwise Compressive Strength testing, the specimens taken from the Coconut Fiber product had higher value of compressive stress compared to the value of specimens taken from Infusion Grooved PVC Foam and 3D Core Foam which is 29.66 MPa, 2.58 MPa and 4.68 MPa respectively. This research has proved that the Coconut Fiber is quite suitable to become as one of the laminating schedule for the construction of the fiberglass boat hull.
Oil and gas production in subsea operation continues to the extreme depth. Harsh environment and ... more Oil and gas production in subsea operation continues to the extreme depth. Harsh environment and severe operation of oil and gas transportation due to high pressure and temperature become crucial for pipeline transportation. Consequently, The pipelines will deform to buckle shape which affect to integrity of pipeline. This phenomenon should be considered in design of pipeline to provide reliability of pipeline operation during time life period. The design result of pipelines is according to DNV F 101 whereas the magnitude of pipeline curvature will validate by ANSYS 14 to ensure pipeline reliability.
This research is targeted to improve the accuracy of diffraction potential theory to predict semi... more This research is targeted to improve the accuracy of diffraction potential theory to predict semi-submersible heave motion response by considering the drag effect in the prediction. From both the numerical and experimental studies, it can be observed that the diffraction potential theory is not predicting well the semi-submersible heave motion response when the motion is dominated by damping. In this research, the viscous damping correction method and Morison equation drag correction method are applied to improve the motion response predicted by diffraction potential theory. This paper will briefly present the procedure to integrate the viscous damping correction method or Morison equation drag term correction method with the diffraction potential theory. The proposed numerical methods are applied in this research to simulate the semi-submersible heave motion response. After that, all simulation results are compared to the experimental result from tests at the same wave condition to validate the proposed numerical methods. From the comparison, it is concluded that Morison equation drag correction method is able to estimate the semi-submersible heave response in the damping dominated region and provides more reasonable motion tendency compare to other methods
ABSTRACT The wave run up under semi-submersible platform deck and the dynamic response are import... more ABSTRACT The wave run up under semi-submersible platform deck and the dynamic response are important design factors, and determine the expected minimum air gap in extreme design conditions. For a semi-submersible, the prediction of probabilities wave run up in harsh environments is a challenging task. This paper addresses the problem of expressing the probability density and cumulative distribution functions that utilize Weibull distribution to model estimates the waves run up for a large volume semi-submersible squared-section columns platform in two sea states. The two parameters Weibull distribution, namely shape parameter and scale parameter were considered. The analysis interpreted the measured data of 9 realizations with different seeds in the moored model experiments. The length of total measured data analyzed included approximately 9 times 250 waves for each sea state. The wave run up was found by model estimates using a Rayleigh distribution, and some waves run up were identical apart from one another for different seeds. Finally, by this model with a sequence return for two sea states the associated motions distribution for the large volume semi-submersible platform were numerically predicted.
The Ocean Thermal Energy Conversion (OTEC) is renewable energy to supply electrical power by usin... more The Ocean Thermal Energy Conversion (OTEC) is renewable energy to supply electrical power by using different ocean temperature between seawater surfaces to a certain water depth. In the OTEC construction, Cold Water Pipe (CWP) is challenging component of OTEC that installed into water depth of >500 m. In this paper the material of CWP is selected the HDPE (High Density Polyethylene), which based on material properties. For commercial scale recently, assembling of joint HDPE pipe uses fusion welding for maximum diameter of 1.6 m. To consider this issue, this paper aims to design the CWP joint using Friction Stir Welding (FSW), which pipe diameter of >12 m. The framework design was performed to short fiber HDPE composite joint process with FSW process. In order to obtain high quality of HDPE joint, optimization of FSW parameters would be highly consideration in joint process. Therefore, this paper revealed a framework design for joint the HDPE pipe in CWP using FSW technique. The proposed framework might provide advantages in technical, investment and time for the FSW process compare to other method of joint process.
Ocean Thermal Energy Conversion (OTEC) is a process that can produce electricity by using the tem... more Ocean Thermal Energy Conversion (OTEC) is a process that can produce electricity by using the temperature difference between deep cold around 28 degree Celsius ocean water and warm tropical surface waters around 6 degree Celsius. Malaysia, Indonesia and the Philippines are located on the equator region which has high potential to implement renewable OTEC technology. Indonesia has many potential locations to build OTEC, among them is in Sumatera Utara, Bali, Flores Sea, Makassar Strait. The OTEC is planned under General Plan of National Energy. The 11th Malaysia Plan (2016-2020) aims to manage the 1st Public-Funded OTEC project of Pulau Layang-Layang, Kuala Baram, Gemusut Kakap, and Pulau Bangi. Philippines as located at geographical position near the equator had passed the Renewable Energy Act of 2008 for OTEC project at Pangasinan, Zambales and Quezon.
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