This study is the analysis and design of a basin structure which has the ability to form a gravitational vortex stream. Such a high velocity water vortex stream can possibly be used as an alternative energy resource. In this study we are interested in the formation of a water vortex stream by gravitation, which is a new technique used in the field of hydro power engineering. The advantage of this method for electrical generation is the capability of producing energy using low heads of 0.7 to 3 meters. It can be applied in a low head micro hydro power plant. The governing equations are the Navier-Stokes equations. The SIMPLE method was adopted to solve the discretized equation. The flow fields in the flume, under different incoming flow conditions and basin configurations, were numerically simulated using the software ANSYS Fluent. The studies investigated parameters which affect the velocity vector flow field, which include 1) Outlet diameter at the bottom center of basin 2) Gravitational vortex head and 3) Flow rate. Computational fluid dynamics is used to simulate the vector flow field. The tangential and radial velocity distribution is used to determine the suitable turbine blade for testing. A gravitational vortex power plant model is created to investigate electrical power output.
Purpose
This paper aims to investigate effect of infill density, fabricated built orientation and dose of gamma radiation to mechanical tensile and compressive properties of polylactic acid (PLA) part fabricated by fused deposit modelling (FDM) technique for medical applications.
Design/methodology/approach
PLA specimens for tensile and compressive tests were fabricated using FDM machine. The specimens geometry and test method were referred to ASTM D638 and ASTM D695, respectively. Three orientations under consideration were flat, edge and upright, whereas the infill density ranged from 0 to 100%. The gamma radiation dose used to expose to specimens was 25 kGy. The collected data included stress and strain, which was used to find mechanical properties, i.e. yield strength, ultimate tensile strength (UTS), fracture strength, elongation at yield, elongation at UTS and elongation at break. The t-test was used to access the difference in mechanical properties.
Findings
Compressive mechanical properties is greater than tensile mechanical properties. Increasing number of layer parallel to loading direction and infill density, it enhances the material property. Upright presents the lowest mechanical property in tensile test, but greatest in compressive test. Upright orientation should not be used for part subjecting to tensile load. FDM is more proper for part subjecting to compressive load. FDM part requires undergoing gamma ray for sterilisation, the infill density no less than 70 and 60% should be selected for part subjecting to tensile and compressive load, respectively.
Originality/value
This study investigated all mechanical properties in both tension and compression as well as exposure to gamma radiation. The results can be applied in selection of FDM parameters for medical device manufacturing.
A combination between two components generally requires screws for assemble them together with high precision and accuracy that is need in industrial application. This research proposes the machine vision technique using Hu-Flussers moments invariant to locate centroids of target screws from a tray for loading instead of the current human vision in manual operation. To validate precision and accuracy template matching is tested in parallel with Hu-Flussers moments invariant. The results show that Hu-Flussers moments invariant is better in terms of precision and have robust ability to exclude outlier too.
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