Noise reduction and control is an important problem in the performance of underwater acoustic systems. As the propeller rotates, it is subjected to unsteady force, which leads to discrete tonal noise, and cavitation. Therefore, underwater propeller noise can be classified into cavitating and non-cavitating noise Furthermore, sound generated by a propeller is critical in underwater detection and it is often related to the survivability of the vessel. This paper presents a numerical study on noises of the underwater propeller for different performance conditions. The non-Cavitating noise generated by an underwater propeller is analyzed numerically in this study. The flow field is analyzed with finite volume method (FVM), and then the acoustic analysis is made by the use of Ffowcs Williams–Hawkings (FW-H) formulation to predict the far-field acoustics at different operating conditions. Noise characteristics are presented according to different positions of hydrophones and speeds of the propeller. Computed results are shown to be in good agreement with experimental results.
Department of Mechanical Engineering, University College of Engineering Vizianagaram, JNTUK, India.
This project presents the study of the safe procedures of LNG loading and unloading operation in port. The purpose of this study is to maintain the safety record of LNG operation for this roughly forty years. The study is carried out by performing ‘one to one interview’ with the port’s safety officer. Then, the collected data from the personal interview is analyzed using Hazard Identification (HAZID) approach. The detail procedures, technical data, and explanation from port’s safety as an expertise in LNG handling field could be needed to determine the potential improvement that could trigger the idea to develop a generic safety model which is refined and improved of the existent holistic model that being reviewed in this study. The model developed in this study is to be applied onto either loading or unloading LNG terminal all over the world. This model is expected to meet the aim of minimizing the unsafe act and near miss which is always be the initiation point of harmful incident and accident. Model which has been developed is an improved and refined version of a generic safety model. The model developed describes the integration of technologies within the system of working competency which also reconsidering the individual performance. In the same time, it aimed to reduce the probabilities of the crews or operators to engage with unsafe act which always introduce the consequence of near miss, which is to be minimized in this research. The model developed in this study is called ‘H-T-D’ safety model, which stand for human factor, technical handling, and design element.
Marine Technology Centre, Institute of Vehicle Engineering, Universiti Teknologi Malaysia, Malaysia
Universiti Malaysia Terengganu, Malaysia.
Ocean and Aerospace Research Institute, Indonesia
Jabatan Fizik, Fakulti Sains, Universiti Teknologi Malaysia, Malaysia
The purpose of this study is to obtain bovine bone powder with high content calcium-phosphorus coumpound through combination of ball milling and heating processes. These processes was carried out in four stages at a temperature of 800°C for heating process. The obtained powder was then mixed with zirconia and resin, and then molded into a metal mold to obtain artificial bone prototypes in the form of dog-bone tensile test specimen. The tensile test was then conducted to the specimens to obtain the strength and strain capacity of the artificial bones. Fractured specimen surface morphology and sample microstructure were then examined using a scanning electron microscope (SEM) equipped with Energy Dispersive X-ray (EDX). The result of this study shows that the highest levels of calcium and phosphorus contents is 35.07% and 19.04%, respectively, with powder fineness of 63 μm. The strength of artificial bone varies according to the powder volume fraction, where the fraction of 90% powder and 10% resin gives the strength 5,57MPa. While the fractions of 80-20, 70-30 and 60-40 give the strength of 11.84 MPa, 13.66 MPa, and 9,56 MPa, respectively. The microstructure of the specimens shows micro cracks, voids, detachement particles, and agglomeration with different extent depend on the fraction of the powders.
Department of Mechanical Engineering, Faculty of Engineering, University of Andalas, Padang, Indonesia
