A propulsion mechanical device is a type of system that is claimed to produce net external thrust by using just the motion of internal components. Despite recent efforts to develop such a device, only a scientifically sound proposal would be an option to develop practical systems in the future.This review presents a theoretical propulsion mechanical device, called the Hummingbird System, which is summarized in several concepts to describe its performance. These concepts include the Basic Model to explain the generation of thrust, the Continuous Model to allow a constant generation of thrust, the Basic Unit to compensate the torque and direct the thrust, and a proposal to cluster several Basic Units to displace an object in space. Some potential applications of the Hummingbird System are also discussed, suggesting its use in naval, artificial satellite, and spacecraft propulsion systems. The ultimate aim of this review is to encourage the design and development of novel propulsion devices that are based on the Hummingbird System. The theoretical concepts that are described in this review remain to be confirmed in practice.
The Hummingbird System Initiative, Helsinki, Finland.
The defense equipment technology development which is in this case is the submarine research became an important subject and need to be further researched. One part of it is, designing driving components (propeller) of a mini-submarine with a high level of efficiency. Test models of mini-submarines of 22 m was used as a basis for developing propeller through scale models with the scale factor of 1:7. Expected propeller design optimization is capable of producing high effisensi currently working on the operational speed propeller. This research method is based on the results of the propeller design optimization, numerical simulations using Computer Fluid Dynamic (CFD ) and hydrodynamic test. The results of this study shows that the method applied here could provide a solution in the choice of an efficient propeller designs for mini-submarines 22 m.
Indonesian Hydrodinamic Laboratory (IHL), Agency for The Assessment an Aplication of Technology (BPPT), Indonesia
At this time, we owning many geophysics methods that can be used to optimize investigation and natural source exploration under layer surface, one of them isGeoresistivity method. Georesistivity method is one of geophysics method that study about electricity in the earth and also to detect an object in the surface layer area of earth. The following, a technology is showed to investigation and analyzed aquifer at botanical garden area, Mekarmanik village, PasirImpun, East Bandung West Java, using Georesistivity method, Wenner Configuration. In this research, will be do Georesistivity method with Wenner configuration and be processed with using inversion from software Res2DIV, and Isopach aquifer contour mapping, which previous be done the topography correction. Based on the inversion obtained, we be obtain to interpret some points which showed aquifer position, are as follow : 1). Line 1 on location 1, with the distance of extend is between 78 – 140 metre on surface layer. (It has medium aquifer) which the resistivity is 800 ohm metre, and also has porosity and volum value 25% and 945,9 m3 with the depth is 60 metre. Its formation rocks at this location are sandstone, and limestone, anticline topography, dominated by normal fault which the trend is NE-SW. 2). Line 6 on location 1 (The highest aquifer) with the distance of extend is between 26 – 182 metre 26 - 160 metre, which the resistivity is 100 – 300 ohm metre, porosity and volum value are 14,14 – 18,26% and 1160,85 m3, with the depth target is 70 metre. Its formation rocks at this location are sandstone, alluvial and limestone, syncline topography, dominated by normal fault which the trend is NE-SW. And then the third is line 8 on location 2 with the distance of extend is between 26 – 182 metre, the resistivity is 100 ohm metre, which its porosity and volum are 14,14 %, and 264 m3, with depth target is 35 metre. It has undulation topography which the trend is SE – SWdominated by normal fault, and its formation rocks are tuff, sandstone, gravel formation.
Department of physics, Faculty of Engineering, Mathematics and Natural Sciences, Indraprasta PGRI University, Jakarta, Indonesia
During itsoperation time, cylindrical pressure vessel could experience cracks. If this happens, the question is raised whether the pressure vessel could still be used or not, moreoever whether further treatment is required. In process and petroleum industry, an integrity analysis using Fitness For Service methodology is common, for instance referring to API 579/ASME FFS-1 2007 Code. Level 3 assessment within the Code requires a finite element simulation in order to generate both the evaluation point and the Failure Assessment Diagram (FAD) that serves as an acceptance criteria. Here, a parametric study based on the methodology given by the Code has been carried out to generate such result for the cases of internal longitudinal crack defect in a cylindrical shells for a number of common cases, in terms of thickness-to-radius ratio, crack size ratio, and crack aspect ratio. The evaluation of Stress Intensity Factor is determined through J-integral parameter found using a finite element analysis with a specially-meshed strategy incorporating the crack. The result of the model is first verified with that of the Code for a number of cases, before being used for parametric study. The model yields a relatively close comparison with that of the Code. A number of regressed equation was derived for several cases, and proposed to be used in integrity assessment of cylindrical shell. A procedure of using the parametric study result from this investigation is also outlined here.
Mechanical Engineering, Universitas Riau, Indonesia
Mechanical and Aerospace Engineering, Institut Teknologi Bandung, Indonesia