Optimization of Co-Flow Jet Parameters for Ahmed Body Application

This study evaluates the drag reduction strategy of suction and blowing on idealize automotive vehicle,Ahmed Body. Optimization approach is adapted in order to analyse the effect of slot location, momentumcoefficient and slot angle on the vehicle which experiencing drag. Despite all the efforts that have been done toreduce the Ahmed body drag using various active flow control system, most of the drag reduction were only lessthan 15%. A 25° Ahmed body with build in co-flow jet is modelled using a CAD software. The flow around theAhmed body is simulated at Reynolds number based on length Re = 4.29 × 10 6 . The governing equation were solveusing an open source software package, which has been validated against experimental data. Pressure Implicit withSplitting of Operator (PISO) algorithm is applied to solve the equation. The outcome of the simulation are variesdepending on the variables. Some show a decrease in drag while there are also that actually increase the drag of thesystem. This are caused by the suction and blowing slots that effect the surrounding air flow whether it is reducingor increasing the wake size downstream of the body. The result shows the momentum coefficient and location ofboth suction and blowing jet played an important role of manipulating the flow around the body and reducing thedrag. The velocity contours indicated that the key to drag reduction is by using 40 m/s jet velocity, placement ofsuction and blowing away from each other. &nbsp

A decentralized proportional-integral sliding mode tracking controller for a 2 D.O.F robot arm

Trajectory tracking with high accuracy is a very challenging topic in direct drive robot control. This is due to the nonlinearities and input couplings present in the dynamics of the arm. This paper deals with the tracking control of a class of direct-drive robot manipulators. A robust Proportional-Integral (PI) sliding mode control law is derived so that the robot trajectory tracks a desired trajectory as closely as possible despite the highly non-linear and coupled dynamics. The controller is designed using the decentralized approaches. Application to a two degree of freedom direct drive robot arm is considered

Optimization of Co-Flow Jet Parameters for Ahmed Body Application

This study evaluates the drag reduction strategy of suction and blowing on idealize automotive vehicle,Ahmed Body. Optimization approach is adapted in order to analyse the effect of slot location, momentumcoefficient and slot angle on the vehicle which experiencing drag. Despite all the efforts that have been done toreduce the Ahmed body drag using various active flow control system, most of the drag reduction were only lessthan 15%. A 25° Ahmed body with build in co-flow jet is modelled using a CAD software. The flow around theAhmed body is simulated at Reynolds number based on length Re = 4.29 × 10 6 . The governing equation were solveusing an open source software package, which has been validated against experimental data. Pressure Implicit withSplitting of Operator (PISO) algorithm is applied to solve the equation. The outcome of the simulation are variesdepending on the variables. Some show a decrease in drag while there are also that actually increase the drag of thesystem. This are caused by the suction and blowing slots that effect the surrounding air flow whether it is reducingor increasing the wake size downstream of the body. The result shows the momentum coefficient and location ofboth suction and blowing jet played an important role of manipulating the flow around the body and reducing thedrag. The velocity contours indicated that the key to drag reduction is by using 40 m/s jet velocity, placement ofsuction and blowing away from each other. &nbsp

Tahap pengetahuan pelajar tentang konsep menutup aurat: suatu tinjauan umum

The philosophy and concept of covering the aurah in Islam should be clearly understood by Muslims. This is because the standard of covering the aurah in Islam is very different from the views of other beliefs and philosophies. The obligation to cover the aurah as commanded by Allah SWT is very clear and detailed as well as universal in nature. When this concept is clearly understood, then there should be no confusion among Muslims to internalize and practice this ruling that is demanded by Islam. Related to this, a brief study was conducted involving students at one of the institutions of higher learning to get an idea about their perception and level of knowledge and understanding regarding the concept of covering the aurah. A total of 120 students participated in this study. The findings show that the level of students? knowledge pertaining to the obligation related to the covering of aurah is high (mean = 3.91). Besides discussing the findings, the researchers also proposed suggestions to further strengthen the efforts to induce awareness in students regarding the obligation of covering the aurah

Community perspectives of governance for effective management of marine protected areas in Malaysia

Marine Protected Areas (MPAs) are useful tool for conserving biodiversity and managing fisheries. The government of Malaysia has established several Marine Protected Areas (MPAs) to enable overexploited marine resources to recover and to conserve coral reef ecosystems. The paper investigates the effect of governance approach on the effective management of two MPAs, Perhentian and Kapas marine parks in Terengganu State of Peninsular Malaysia. The data for this study was obtained from face-to-face interviews with local people from two MPAs using a structured questionnaire. The results of the analysis show that local participation in MPA management and fisheries regulations are significant factors for the effective MPA management in the study areas. The regression results show that users' participation has contributed significantly to the MPA governance, which indicate that local peoples' participation play an important role for effective management of MPAs in Malaysia. The MPA management activities should be coordinated with other relevant agencies and local users to achieve successful management of MPAs in Malaysia. There is a need to give priority to encourage local fishers' participation in decision making for MPAs management in the future marine resource conservation policy in Malaysia

Development and Experimental Investigation of a Marine Vessel Utilizing the Energy Ship Concept for Far Offshore Wind Energy Conversion

The energy ship is a concept for offshore wind energy capture which has received very little attention until today. To this date, there had not been yet an experimental proof of concept. In order to tackle this issue, an experimental platform and data acquisition system has been developed. A 5.5m long sailing catamaran served as a platform equipped with a 240mm diameter water turbine. The energy ship platform has been tested several times in the actual river to investigate the workability of the platform and data acquisition system. Results show that energy ship platform can produced 500W electric power for a true wind speed of 10 knots

A Tunable Ferrofluid-based Polydimethylsiloxane (PDMS) Microchannel Inductor for Ultra High Frequency Applications

In this work, a tunable ferrofluid-based polydimethylsiloxane (PDMS) microchannel inductor with high quality factor and high tuning range is proposed. For this project, PDMS is used to create a microchannel with a width and height of 0.53 mm and 0.2 mm respectively. The microchannel is then used to cover the whole design of a solenoid inductor. A solenoid inductor is designed using wire bonding technique where lines of copper and bond wires are used to form a solenoid winding on top of silicon substrate. A light hydrocarbon based ferrofluid EMG 901 660 mT with high permeability of 5.4 is used. The ferrofluid-based liquid is injected into the channel to enhance the performance of a quality factor. A 3D full-wave electromagnetic fields tool, ANSYS HFSS is used in this work to simulate the solenoid inductor. The results obtained in this work gives a quality factor of more than 10 at a frequency range of 300 MHz to 3.3 GHz (Ultra High Frequency range). The highest quality factor is 37 which occurs at a frequency of 1.5 GHz, provides a high tuning range of 112%

Wake modifications in confined flows due to the presence of a downstream cylinder in staggered arrangement

In the present study, confined flows around two square cylinders in staggered arrangement were numerically investigated. Cross-flow and streamwise center-to-center spacings of one- and three-cylinder diameters, respectively, were considered. Simulations were carried out at Reynolds numbers Re = 50,100,150 and 180, where the resulting wakes are laminar and periodic. Results indicate that the presence of the downstream cylinder tends to reduce the Strouhal number, amplitude and the time-averaged lift coefficient of the upstream cylinder relative to the single cylinder cases. Furthermore, the time variations of upstream cylinder’s lift coefficient behave similar to that of a single cylinder

Indicators of governance of marine ecotourism resources: perception of communities in Pulau Perhentian, Terengganu

To be effective, the establishment of the Marine Protected Areas requires support from various stakeholders, which are directly or indirectly affected by the establishment. The support of relevant agencies to manage the Marine Protected Areas may depend on how the communities perceive the benefits of the establishment. The objective of this paper is to present the results of an analysis on the perception of local communities on the governance of the Marine Protected Areas by the relevant agencies. Data for the study were collected from members of the local communities on Pulau Perhentian using face-to-face interviews. The results show that most members of these communities were aware of the establishment of the Marine Protected Areas, though some were doubtful of the actual benefits of the establishment. Communities on Pulau Perhentian, which were directly dependent on the marine resources for their ecotourism-related businesses, were quite apprehensive of the ability of relevant agencies to act on reducing the encroachment of fishers in protected zones. Generally, the local communities agreed that the relevant agency were doing a good job of enforcing rules and regulations to protect the resources in the marine ecosystem. The cooperation among the stakeholders in adapting to the norms of governance was perceived as helpful in affecting the management of Marine Protected Areas