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In order to study the influences of frictional coefficient on nonlinear dynamics of face-gear transmission system, a nonlinear dynamic model with multiple degrees of freedom is presented by the method of concentrated parameters. The model includes frictional, gear clearances, general transmission error, time-varying meshing stiffness, meshing damping, brace stiffness, support damping, exciting frequency, and external load, etc. The Runge-Kutta numerical integral method used to solve the dynamic differential equations. And the bifurcation characteristics were obtained under different rotation speeds and external loads. The calculation results show that the nonlinear dynamics characteristics of face-gear transmission system contain periodic response and chaotic response, and the amplitude is increased with the frictional coefficient increasing. [ABSTRACT FROM AUTHOR]

Coexisting Periodic solutions and their stability of a nonlinear torsional vibration model for a planetary gear train with gear backlashes are studied by using the method of PNF. Some adaptations are made for the PNF method so as to make it suitable for the non smooth and nonlinear planetary gear train. The coexisting periodic solutions of the system under certain dimensionless rotational speed are studied by using the method of modified PNF,with the stability of each periodic solution investigated at the same time. The bifurcation characteristics of the periodic trajectories are studied as well by using PNF at different speeds. The results show that a nonlinear planetary gear train with certain parameters may have several coexisting stable or unstable periodic trajectories Moreover, the motion of the system could also evolve into chaos by way of period doubling bifurcation as the speed increases. [ABSTRACT FROM AUTHOR]

A dynamics model of herringbone planet train with double teeth coupling is established based on the vibration theory of the concentrated parameter. The mesh stiffness formula of the helical gear is introduced to calculate the time-varying mesh stiffness of the herringbone teeth in the way of stiffness parallel of two helical gears. The relationship curves between the mesh stiffness of the internal and external meshes and the dynamic load coefficients of the internal and external meshes are obtained by solving the dynamic equation, and the impact of the mesh stiffness of the internal and external meshes on the dynamics load characteristics of the train is analyzed. The research results show that the dynamic load coefficients of the internal and external meshes increase with the average components of the mesh stiffness of internal and external meshes without regard to the resonance, respectively. The impact of the alternate component of the mesh stiffness of the internal and external meshes on the dynamic load coefficients is much less. Because of smooth operation and small vibration of the herringbone tooth, it is feasible that the average component of the mesh stiffness represents the mesh stiffness for the calculation of dynamic load coefficient of herringbone planetary train, when the required accuracy is not too high. [ABSTRACT FROM AUTHOR]

Extracellular recording is a key technology to study many types of brain functions. However the amplitudes of extracellular spikes are typically about 100 muV and should be picked up and amplified specially, then recorded and analyzed online. Most of the equipment for extracellular recording are either very expensive, or too large for recording in the brains of freely moving small animals. In this paper we developed a practical multi-electrode recording system based on virtual testing technology. The system includes microelectrode amplifier, analog input device NI4472 with 24-bit resolution, and data processing software SPKrec. The features of the hardware are low noise, high input impedance, a total gain of 2 000, and large dynamic range. The software developed in LabVIEW is capable of online analysis, data recording, spike detection, fire rate histograms, etc. The system functions have been verified in extracellular recording in the olfactory bulb of Gekko gecko. The result indicates that the system with performance comparable to that of commercial products meets the requirements of recording experiments.