DYNAMIC MODEL AND SIMULATION OF A NOVEL ELECTRO-HYDRAULIC FULLY VARIABLE VALVE SYSTEM FOR FOUR-STROKE AUTOMOTIVE ENGINES

In modern four-stroke engine technology, variable valve timing and lift control offers potential benefits for making a high-performance engine. A novel electro-hydraulic fully variable valve train for four-stroke automotive engines is introduced. The construction of the nonlinear mathematic model of the valve train system and its dynamic analysis are also presented. Experimental and simulation results show that the novel electro-hydraulic valve train can achieve fully variable valve timing and lift control. Consequently the engine performance on different loads and speeds will be significantly increased. The technology also permits the elimination of the traditional throttle valve in the gasoline engines and increases engine design flexibility.     

FORWARD KINEMATICS ANALYSIS FOR A NOVEL 5-DOF PARALLEL MECHANISM USING TETRAHEDRON CONFIGURATIONS

Forward kinematics analysis of a novel 5-DOF parallel mechanism using tetrahedron configurations is presented. Such mechanism is suitable to many tasks requiring less than 6 DOFs. It consists of a movable platform connected to the base by five identical 6-DOF active limbs plus one active limb with its DOF being exactly the same as the specified DOF of the movable platform, which leads to its legs' topology 4-UPS/UPU. Based on the tetrahedron geometry, both closed-form solution with an extra sensor and numerical method using iterative algorithm are employed to obtain the forward kinematics solutions of the mechanism. Compared with the conventional methods, the proposed closed-form solution has the advantages in automatically avoiding unnecessary complex roots and getting a unique solution for the forward kinematics. Finally, an example shows that the proposed numerical algorithm is so effective that it enables a real-time forward kinematics solution to be achieved and the initial value can be chosen easily.     

Chemically formulated ceramic gamma ray irradiation shielding materials utilising red mud

Abstract

Novel shielding materials for electromagnetic radiations have been formulated using two different approaches using red mud and processed red mud based systems. The crystallographic aspect of multicomponent and multishielding phases, in the formulated shielding materials, on the shielding efficiency has been studied. The formulated shielding materials have been evaluated for radiation attenuation using Co-60 gamma ray irradiation source and were found to reduce the shielding thickness, i.e. half value thickness, to about 40–60% of concrete. The X-ray diffraction studies confirmed the presence of bafertisite, sanbornite, celsian and troilite as the major shielding phases and phosphates of aluminium and iron as the binder phases. The SEM revealed the highly compacted and continued integrated morphological features of various shielding phases. The unique combination of these different phases is responsible for providing bonding to the ceramic matrix leading to the effective shielding and mechanical properties.