Conceptual Design of Co-Axial Floating Multiple-Rotors Water Current Turbine (FMRCT)

Depletion of fossil fuel as well as increasing in price had pressured the world energy to give focus on renewable energy. This paper interest is to describe the conceptual design of a floating multiple-rotor water current turbine (FMRCT) as well as to investigate the effect of distance between two rotors over diameter ratio (S/D) towards power output increment. Further, the contribution of each rotor toward the FMRCT power output increment also will be discussed. With the interest to increase output power, FMRCT concept design is where few rotors were arranged in series with a suitable distance between each rotor, fitted with a floater at one end, and connected to a generator at the other end. The FMRCT model was tested in an open stream at Lata Ulu Licin (Lecin). Results show that increment of the output voltage is very significant as S/D increased up to S/D = 1.48. Furthermore, extra rotor on FMRCT also proportionately increase the power output, ranging almost similarly from 6.28% to 8.91% of power

Extraction of natural hydroxyapatite for biomedical applications—a review

Hydroxyapatite has recently played a crucial role in the sustainable development of biomedical applications. Publications related to hydroxyapatite as filler for biopolymers have exhibited an increasing trend due to the expanding research output. Based on the latest publications, the authors reviewed the research trends regarding hydroxyapatite use in biomedical applications. Analysis of the Scopus database using the keywords ‘hydroxy�apatite” and “biomedical applications” determined that 1,714 papers were produced between 2012 and 2021. The number of publications related to these keywords more than doubled between 2012 (99) and 2021 (247). The hydrothermal method, solid-state reactions, the sol-gel process, emulsion, micro-emulsion, and mostly chemical precipitation were used to produce synthetic hydroxyapatite. Meanwhile, calcination, alkaline hydrolysis, pre�cipitation, hydrothermal, and a combination of these techniques were used in producing natural hydroxyapatite. Studies in the current literature reveal that shell-based animal sources have been frequently used as hydroxy�apatite resources during investigations concerning biomedical applications, while calcination was the extraction method most often applied. Essential trace elements of fish bone, oyster shell, and eggshell were also found in hydroxyapatite powder. Abalone mussel shell and eggshell showed Ca/P ratios closer to the stoichiometric ratio due to the use of effective extraction methods such as manipulating aging time or stirring process parameters. This review should greatly assist by offering scientific insights to support all the recommended future research works, not only that associated with biomedical applications

Extraction of natural hydroxyapatite for biomedical applications—a review

Hydroxyapatite has recently played a crucial role in the sustainable development of biomedical applications. Publications related to hydroxyapatite as filler for biopolymers have exhibited an increasing trend due to the expanding research output. Based on the latest publications, the authors reviewed the research trends regarding hydroxyapatite use in biomedical applications. Analysis of the Scopus database using the keywords ‘hydroxyapatite” and “biomedical applications” determined that 1,714 papers were produced between 2012 and 2021. The number of publications related to these keywords more than doubled between 2012 (99) and 2021 (247). The hydrothermal method, solid-state reactions, the sol-gel process, emulsion, micro-emulsion, and mostly chemical precipitation were used to produce synthetic hydroxyapatite. Meanwhile, calcination, alkaline hydrolysis, precipitation, hydrothermal, and a combination of these techniques were used in producing natural hydroxyapatite. Studies in the current literature reveal that shell-based animal sources have been frequently used as hydroxyapatite resources during investigations concerning biomedical applications, while calcination was the extraction method most often applied. Essential trace elements of fish bone, oyster shell, and eggshell were also found in hydroxyapatite powder. Abalone mussel shell and eggshell showed Ca/P ratios closer to the stoichiometric ratio due to the use of effective extraction methods such as manipulating aging time or stirring process parameters. This review should greatly assist by offering scientific insights to support all the recommended future research works, not only that associated with biomedical applications

Computational Fluid Dynamics Study Of Wake Recovery For Flow Across Hydrokinetic Turbine At Different Depth Of Water

Depletion of fossil fuel caused mankind to look for sustainable and green energy resources. The characteristic of hydrokinetic turbine with ability to operate at low head stream and at low cost made it a good choice for use to harness hydro source of energy. As hydrokinetic turbine gain attention from the industry player, many experimental and Computational Fluid Dynamics (CFD) studies related to hydrokinetic turbine have been carried out. Yet the relationship of flow depth variation and wake recovery behind the turbine is still not fully understood. There is limited study about the effects of flow depth variations on the wake recovery behind the turbine. In this paper, a CFD model investigation was done based on published experimental work. A hydrokinetic water turbine was drawn using the MHKF1-180 and NACA4418 foils dimensions. The transient CFD study was conducted using SST k- turbulence model and dynamic mesh method. The results showed that in near wake region, the wake at deeper depth will recover faster seemingly due to pressure change at that depth and the faster rate of momentum transfer of the fluid. It can be concluded that the deeper the placement of the turbine inside the water channel, the faster the wake recovers. The wake recovery results as presented in this paper should be considered when placing set of turbines especially in array arrangement to obtain a more efficient energy conversion

Biomechanics and hydrodynamics study od aquatic locomotion

This study was conducted in order to characterize propulsion and control surface (caudal fin) of Anabas testudineus (puyu) based on distance travelled, resultant speed and acceleration. Fish was trained to swim along a 2 x 1 feet long aquarium. Two fish (adult and juvenile) were kept in the aquarium at a time to stimulate a competitive situation and induce burst swimming sequences. Spontaneous swimming along the aquarium was filmed and analysed. A CCV-A11b (Progressive Scan Monochrome Camera) was positioned 180 cm above the base of the aquarium to provide dorsal views of swimming sequences. Images from video recordings (20 frames s¯¹) were analysed frame by frame using global coordinates system, with time interval 0.05s. When sub-carangiform alone was used it was found that in both juvenile and adult, the distance travelled by the tail tip was always greater than the distance travelled by the body. In contrast, when sub-carangiform was used in combination with labriform locomotion, the distance travelled by tail tip was less than the distance travelled by the body, which is comparable to the double propulsion system found in marine vehicles. Apart from that, other findings revealed that juvenile fish had higher acceleration rate compared to an adult for a given time. Overall, A. testudineus were more efficient swimmers in their juvenile forms than in adulthood based on their distance travelled, speed, acceleration and distance travelled ratio