A natural human tooth consists of enamel, dentin, pulp and cementum, and its root structure is surrounded by the periodontal ligament (PDL) (Figure 1). The PDL is a soft, highly vascular and specialized connective tissue that surrounds the tooth root and attaches it to the alveolar bone. 1,2 The main components of the PDL are functionoriented elastic fibres, tissue-containing cells (eg, fibroblasts, osteoclasts, osteoblasts, cementoblasts, mastocytes and macrophages), blood and lymphatic vessels, and nerves that are connected to the tooth pulp, the tooth socket, and the gingiva. 3,4 It consists of 53%-74% collagen fibres, 1%-2% blood vessels and nerve endings, rooted

Concentrated sunlight has been used to perform useful tasks from ancient time. There are number of varieties of collector trough being used to perform these tasks. Each Varity comes with advantages as well as disadvantages. The aim of this research project is to improve the design of collector trough in terms of efficiency, lessen the heat declination, and eliminate the sun tracker mechanism. Most of the existing solar concentrators use open type trough which cause the rapid heat declination. The design attempted in this paper is to lessen this rapid declination and improve the efficiency by introducing Closed Environment Collector Trough (CECT). The CECT consists of spherical collector trough having a reflective bottom surface, five evenly distributed lenses, 30 o apart from each other, on the upper half of the sphere to eliminate the sun tracker and hexagonal glasses to make the environment closed and impose greenhouse effect on the system. The CECT acts like a heat trap and keeps the heat inside the chamber for a longer period of time which basically lessens the heat declination. The reflective surface and lenses concentrate the sun light directly on the fluid pipe. In this paper novel design has been proposed to improve the overall performance of solar collector troughs.

Abstract:The main disadvantage of Electric Vehicle is the lack of capability of storing sufficient energy to run the vehicle for a long time. The energy storage capacity of battery used in electric vehicle is very low compare to conventional fuels used in modern automobiles. The operation, performance and efficiency of motor driven electric vehicles are much better than engine driven vehicles, at the same time electric vehicles are very much environment friendly. Still electric vehicles are falling behind in the automobile industries due to the problem of storage of energy. This paper is based on the concept of charging the batteries of an electric vehicle when it is in motion or propelling. This may be done by using the energy of wind which is caused by the relative motion between the vehicle and the wind surrounding it. Wind turbines can be mounted on the body structure of the vehicle to generate electricity in such a way that it must not create any additional drag force (rather than the existing drag force due to frontal area and skin friction) upon the vehicle. An elaborate aerodynamic analysis of the structure of the vehicle along with the flow pattern and wind turbine is presented in the paper. Some techniques and methods are proposed to minimize the drag imposed by the introduction of the turbines as much as possible. Optimum values of different design parameters and rated velocity of the vehicle are of prime concern. With this concept it may be possible to increase the mileage of an electric vehicle up to 20%-25% and it will also save the charging time of the battery to a great extent. Flow pattern over the vehicle is simulated using software called ANSYS CFX.

Rotor-to-stator or rotor-to-guide rubbing in rotating machines is a serious problem. The contact (rub and impact) between the rotor and the guide creates an excessive vibration which may lead to permanent damage of the mechanical system. In the present work, the rubbing phenomenon between the rotor and the guide is investigated by simulation and experiment. Two different types of clearance bearings are implemented, which are based on circular and lemon-type guides. Rigorous mathematical models for the lemon-type guide as well as for the traditional circular clearance bearing are derived. Then, a Jeffcott rotor model is simulated for the investigation of the rubbing behavior for the two types of bearings. The numerical model is developed in matlab simulink. For different clearances and friction levels between rotor and guide, and several initial conditions, the rubbing phenomena are studied and evaluated. Finally, a comparison between experimental and simulation work is carried out to validate the overall scenarios in this research work. Results indicate that the lemon-type bearing can reduce the likelihood of sustained rubbing, compared with the circular clearance bearing, for the considered test cases.

Two-degree-of-freedom vibro-impact model with clearance nonlinearity of torsional vibration is presented in this paper. Clearance in coupling in any rotating machinery can exhibit chaotic and multiple periodic phenomena. Coupling inertia also contributes to change the vibration characteristic significantly. In this paper, coupling effects, from a small inertia to large inertia compare to rotor, have been investigated for a wide frequency zone by simulation and some experiments focusing on resonance and bifurcation diagrams. As the spring in the clearance usually possesses quite low stiffness compared to shaft stiffness, symmetric and asymmetric characteristics can be exhibited. The results found are noticeably different from each other for the symmetric and asymmetric conditions. The presence of vibro-impact due to clearance can cause periodic, multiple periodic and chaotic motions.