Abstract: Integrated launch systems that include aerospace plane (ASP) and another heavy winged vehicle (plane or better Wing-in-Ground effect vehicle) as a booster are reviewed. It is shown that WIG-vehicle with a mass of 1500 ton or more is capable to carry ASP with initial mass of 500 ton and landing mass of 60-70 ton. Ekranoplane can provide ASP with the primary speed of Mach 0.5-0.65 in the required direction that allows lowering the design requirements to ASP's wing area and engines. A number of other advantages from the offered transport system are linked to possible use of WIG-vehicle at ASP landing. Heavy WIG-vehicle is unique vehicle for realizing the progressive idea of docking to descending ASP, allowing expanding opportunities of its landing. The problem of ASP horizontal landing without undercarriage by docking with other flying vehicle at the last stage of decent and the requirements to control systems for relative motion control of both vehicles are discussed. The progressive idea of joining space launch technologies with marine technologies is developed. It is especially important for countries with strongly limited areas of land territory but with easy access to the ocean.
Abstract: Airliner cabins present more complicated scenario due to different design and operation challenges owing to the extreme environmental conditions, complexity of the operational systems, and the authorities that govern such environments. The scientific evaluation is rendered difficult due to lack of empirical evidence determining the airliner cabin air quality as well as consequent health effects occurring due to short or long flight exposure. Crew members and passengers report dizziness, fatigue, headaches, sinus and ear problems, dry eyes and sore throats during and after travel. There are persistent concerns about the transmission of infectious agents such as influenza, tuberculosis and measles viruses during flights. Moreover, a systematic collection of data related to airplane environmental exposures is not yet available and the effects of environmental conditions on wellbeing of travelers and their comfort level are yet to be fully ascertained. In this work, a systematic review of the air quality inside the airliner cabin are discussed. The potential pollutants and their established causes are discussed. In addition to this, major health discomforts faced by the occupants are presented.
Abstract: The fast growing use of composite in many applications has been focused on sustainable and renewable reinforced composites. Natural fibres were introduced and increasingly used due to their availability and environmental issues. Kenaf is the most common natural fiber used as reinforcement in polymer matrix composites (PMC). Therefore, this study analyzes the bending fatigue for kenaf fiber hollow shaft composite. The wet filament winding technique was used to prepare the composite specimens for the bending fatigue test. Different orientation angles (45° and 90°) and reinforced with aluminum were studied.
Abstract: Unmanned Aerial Vehicle (UAV) has been used in military application even during the conflicts in World War II. The utilization of UAV was further expanded during the Vietnam War and the role of “eye in the sky” has seen UAV became the ultimate ISTAR (Intelligence, Surveillance, Target Acquisition and Reconnaissance) tool for almost all conflicts. The evolution of UAV in various sizes and features will see UAV saturating the battlefield theater’s cloud in the future. This paper is to present the concept of operations of UAV in the military, segmented by units in battle to enable researchers to concentrate their research on types of UAV to suit the needs of the Malaysian Army.
Using effective firepower range of all Malaysian Army arsenals and the commonality in terms of tasking, this study is able to establish the classes in terms of range needed for UAV in the Malaysian Army. From the observation, it is clear that the majority of the intended UAV will be operating in the less than 3 km combat radius.
Abstract: Although fundamental, vibration of a cantilevered Euler-Bernoulli beam with spring attached at the tip is not found in literatures and is here solved analytically and numerically using finite element approach. The equation of motion of the beam is obtained by using Hamilton’s principle. Finite element method is utilized to write in-house program for the free vibration of the beam. Results show plausible agreements.
Abstract: Cavitation is a phenomenon that frequently creates fear within the engineering industry as the violent and critical attacks by cavitation can cause a lot of damage to ball valves. This paper is presented to reduce the risk of cavitation attack due to dramatic pressure drop and to demonstrate the ball valve performance. The ball valve with grooves was simulated and compared with current method under same boundary conditions as with existing experimental of ball valves. The proposed device can be operated in aircraft to isolate the fuel system and the engine fuel system after engine shutdown or emergency. The proposed implementation has successfully shown to eliminate the dramatic pressure drop effects to the ball valve. In the case study, at a closing angle of 40° at which violent cavitation occurs, the ball valve showed increasing cavitation intensity performance to 0.3 or 30%. The average performance of the cavitation index for all cases also increased to 24%.
Abstract: Sintering parameters are undoubtedly among the many factors that influence the mechanical properties and hydrothermal ageing resistance of tetragonal zirconia ceramics. In this research, the effect of using short holding times i.e. (1 min., 30 min. and 1 hour) as compared to the conventional 2 hours during sintering of 3 mol% Yttria Tetragonal Zirconia Polycrystals (3Y-TZP) on the mechanical properties were systematically investigated. The research revealed that holding time of 1 minute and sintered at 1400oC yielded a high relative density (above 95% of theoretical density) and high Young’s modulus (above 180 GPa) without compromising on tetragonal phase stability and mechanical properties. The study also revealed that the bulk density is an important parameter governing the matrix stiffness of 3Y-TZPs and that grain size strongly influences the transformability and consequently, the toughness of 3Y-TZPs. The toughness of the ceramic was observed to increase steeply when grains exceeded 0.52 µm, which has been identified as the critical grain size for toughening.
Abstract: Flow structure over bluff bodies is more complex in wake. The wake is characterized by the unsteady behavior of the flow, large scale turbulent structure and strong recirculation region. For the case of high speed train, wake can be observed at the gap between the coaches and also on the rear coach. Wakes formation of high speed train are generated by free shear layer that is originated from the flow separation due to the sudden change in geometry. RANS and LES turbulent models are used in this paper to stimulate the formation of wakes and behavior of the flow over a simplified high speed train model. This model consists of two coaches with the gap between them is 0.5D. A total of four simulations have been made to study the effect of computational domain size and grid resolution on wake profiles of a simplified high speed train. The result shows that the computational domain can be reduced by decreasing the ground distance to 1.5D without affecting the magnitude of the wake profile. Both RANS and LES can capture the formation of the wake, but LES requires further grid refinement as the results between the two grid resolutions are grid dependent.
Abstract: In this paper, dynamic behaviors of different chamber neck designs are studied. Within a micro-nozzle channel, different chamber neck designs for controlling bubble growth are used, including conventional structural chamber neck as well as virtual chamber neck. Dynamics of bubble growth rates under different input signals and chamber neck configurations are measured using a high speed microscopic imaging system. The experimental results show that with the help of virtual chamber neck at upstream, the bubble interface will move faster toward the nozzle direction, which will enhance the actuation force of the liquid toward the nozzle direction.
Abstract: Functionally graded material that consists of gradually changed dual-phase compositions along the thickness direction of its structure has been introduced as an answer to sharp interfaces problems occur while the processing. In order to observe the morphological and shrinkage due to the sintering process, the Ni/Al2O3 FG samples were manufactured via powder metallurgy routes under argon atmosphere. This study reveals that the sintering temperature does affects the sintering behaviors including the microstructures and radial dimensions of the FG plates. The numerical simulation is found to be useful to predict the stress concentration area within the structures and consequently improve the design of the FG plates.