Title of the Paper: Complex study on hand-arm system exposed to vibrations
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Authors: Simona Lache
Abstract: The research performed in the domain of human body vibrations revealed their important influence
on human health, being the origin of several professional diseases. Consequently, the vibrations influence can
be clearly systematized in two distinct categories: whole body vibrations – with significant effects in the entire
human body; vibrations on different sections of the body – that transmit significant accelerations and
displacements only in some sections, such as the hand-arm system. While the first category – registered mainly
in the professional driving sector – has been constantly studied and different solutions for vibration attenuation
have been proposed, the hand-arm vibration domain is still open for discussions. This paper presents a complex
study – both from the medical and engineering point of view – regarding the modelling and testing methods
used for hand-arm system vibrations in the view of professional diseases prevention. It aims to evaluating
preventive strategies to reduce worker exposures to hand-arm transmitted vibration and to decrease the
occurrence of Hand-Arm Vibration Syndrome (HAVS) in workers.
Keywords: hand-arm vibrations, occupational health, daily exposure assessment, modelling and simulation.
Title of the Paper: A new study on the optimal prediction of partial transmission ratios of three-step helical gearboxes
with second-step double gear-sets
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Authors: Vu Ngoc Pi
Abstract: This paper presents a new study on the applications of the optimization and regression techniques for optimal prediction of partial ratios of three-step helical gearboxes with second-step double gear-sets for getting different objectives including the minimal gearbox length, the minimal gearbox cross section dimension and the minimal mass of gears. In the study, based on the condition of the moment equilibrium of a mechanic system including three gear units and their regular resistance condition, three optimization problems for getting minimal gearbox length, the minimal gearbox cross section dimension and minimal mass of gears were performed. In addition, explicit models for calculating the partial ratios of the gearboxes were found by using regression analysis technique. Using these models, the determination of the partial ratios becomes accurate and simple.
Keywords: Gearbox design; Optimal design; Helical gearbox; Transmission ratio.
Title of the Paper: Permeability Effect on the capillary and the viscous forces
during the drainage process in porous media
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Authors: Chakib Seladji
Abstract: Two-phase flow and capillarity phenomenon in porous solids are well known in physics and
engineering. In different studies, drainage experiments in porous media, initially saturated with a wetting fluid,
have been largely devoted by using various type of fluids and different angle values of slant to the horizontal
direction, in order to evaluate the effects of gravity forces and the injection flow-rate. However, the influence of
the matrix structure on the capillary and viscous forces as well as the fluids distribution has not been treated
sufficiently. In this study, we simulate an ascending air phase flow in a vertical porous channel initially
saturated with a liquid phase, in order to evaluate the two previous effects. The numerical study is performed
for large range of injected air mass flow rate along the porous channel from the bottom up. The different forces
intervening in the drainage process is analyzed according to several permeabilities. The results show that for a
weak gas mass flow rate, the capillary effect is dominant and the gas saturation in a porous channel is
proportional to the permeability. For more important gas mass flow rate, the saturation behavior becomes
inversely proportional to the permeability of the porous channel.
Keywords: two-phase flow, capillary pressure, viscosity forces, relative permeability, saturation behavior
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