The low-noise optimisation method for gearbox in consideration of operating conditions
This paper presents a comprehensive procedure to calculate the steady dynamic response and the noise radiation generated from a stepping-down gearbox. In this process, the dynamic model of the cylindrical gear transmission system is built with the consideration of the time-varying mesh stiffness, gear errors and bearing supporting, while the data of dynamic bearing force is obtained through solving the model. Furthermore, taking the data of bearing force as the excitation, the gearbox vibrations and noise radiation are calculated by numerical simulation, and then the time history of node dynamic response, noise spectrum and resonance frequency range of the gearbox are obtained. Finally, the gearbox panel acoustic contribution at the resonance frequency range is calculated. Based on the conclusions from the gearbox panel acoustic contribution analyses and the mode shapes, two gearbox stiffness improving plans have been studied. By contrastive analysis of gearbox noise radiation, the effectiveness of the improving plans is confirmed. This study has provided useful theoretical guideline to the gearbox design.
A MATHEMATICAL MODEL FOR ANALYZING THE INFLUENCE OF SHAPE DEVIATIONS AND MOUNTING ERRORS ON GEAR DYNAMIC BEHAVIOUR
Abstract A comprehensive mathematical model is introduced for analyzing the influence of shape deviations and mounting errors on gear dynamics. Contact conditions for both rigid and deformable solids are used for characterizing the gear set excitation sources. The deformed state is modeled by a lumped parameter non-linear system with six degrees-of-freedom on pinion and gear. Each potential contact line on the base plane is discretized in independent elementary cells of constant stiffness and an original procedure is proposed for simultaneously solving the normal contact problem between active flanks and the equations of motion. Comparisons with several results from the literature prove the versatility of the model as static and dynamic load distributions, transmission errors and mesh stiffnesses can be evaluated from a unified approach. Finally, the interest of the methodology is illustrated by some practical problems in gear dynamics: i.e., the influence of some geometrical errors and the role of linear profile modifications on spur and helical gears.
Modulating dopamine receptors subtype selectivity by thiophene and benzothiophene based derivatives
In this work we tried to develop new dopaminergic ligands with novel affinity and selectivity profile towards the five different dopamine receptor subtypes; namely D1, D2, D3, D4, and D5 receptors to come up with new medical agents but with fewer side effects relative to those present in the medicinal market such as Haloperidol that is considered to be among the very famous typical antipsychotic agents characterized with Extrapyramidal symptoms adverse effects and Clozapine that represents the atypical antipsychotic agents that suffers agranulocytosis adverse effects. Among the fifty five synthesized ligands, compounds 3, 44a, and 45a were shown to have unique subtype receptor selectivity, thus could be promising atypical antipsychotic agents. Compound 3 was the first azecine derivative to show antagonistic action on both D2 and D5 receptor subtypes, (Ki (D2): 1.5 nM; Ki (D5): 1.9 nM). Compound 44a showed to be more than 200 times more selective to D2 receptors rather than D4 (Ki (D2): 138 nM; Ki (D4):0.62 nM). Compound 45a has shown to be more than 100 times more selective to D3 rather than D2 receptor subtypes and more than 900 times more selective to D4 rather than D2 receptor subtypes (Ki (D2): 28.5 nM; Ki (D3): 0.26 nM; Ki (D4): 0.03 nM).