Modeling and Experimental Study for Automotive Dry Clutch Sliding Noise

Automotive dry clutches have been found to produce a low frequency sliding noise in many applications,which challenges the ride comfort of vehicles.In order to study this clutch sliding noise,a detailed finite element model including both a pressure plate assembly and a driven plate assembly was developed.Based on this model,a complex eigenvalue analysis is performed in this research.The effect of several major factors on the clutch sliding noise,such as the coefficient of friction,the clamping force,the geometric imperfection of the friction plate,and the thermal deformation of the pressure plate,were investigated numerically.A vehicle road test with clutch sliding noise was conducted for several different conditions.The leading frequencies of the clutch sliding noise in the testing were obtained and compared with the frequencies predicted by the numerical model.The simulation results show the same tendency as the road test.It is found that the clutch sliding noise can be reduced by decreasing the coefficient of friction.With the presence of the surface bumping of the friction plate,the propensity of the clutch sliding noise greatly increases and the corresponding squeal frequencies fall into the range lower than 1 kHz.With the consideration of the thermally introduced deformation of the clutch pressure plate,the possibility of clutch sliding noise is significantly reduced.It is concluded that the model with the incorporation of the thermal deformation of the pressure plate is more effective for the frequency prediction of clutch sliding noise.

Effect of gating currents of ion channels on the collective spiking activity of coupled Hodgkin-Huxley neurons

Based on the coupled stochastic Hodgkin-Huxley neurons, we numerically studied the effect of gating currents of ion channels, as well as coupling and the number of neurons, on the collective spiking rate and regularity in the coupled system. It was found, for a given coupling strength and with a relatively large number of neurons, when gating currents are applied, the collective spiking regularity decreases; meanwhile, the collective spiking rate increases, indicating that gating currents can aggravate the de-synchronization of the spikings of all neurons. However, gating currents caused hardly any effect in the spiking of any individual neuron of the coupled system. This result, different from the reduction of the spiking rate by gating currents in a single neuron, provides a new insight into the effect of gating cur-rents on the global information processing and signal transduction in real neural systems.

Function Modeling of the Infrared Organ of ＂Little Ash Beetle＂ Acanthocnemus Nigricans （Coleoptera, Acanthocnemidae）

Acanthocnemus nigricans is an inconspicuous pyrophilous beetle that approaches forest fires. The beetle is equipped with a pair of unique infrared （IR） receptors on its prothorax that allows it to detect hot surfaces in flight. The IR receptor consists of a little disc bearing about 90 tiny sensilla on its anterior half. The disc sensilla are unique in insects and their functions are largely unknown. Using a 3D reconstruction of the head and thorax we performed case studies to reveal different position-dependent expositions of the IR receptors to incoming radiation~ Results show that the spatiotemporal pattern in which different sectors of the disc are exposed provides the beetle with unambiguous information about its current direction to an IR source. As a striking structural element, the disc sensilla contain an electron-dense rod connecting an outer peg to the inner sensory cell. Finite element simulations suggest that the rod serves as a heat conductor directing heat to the thermosensitive cell inside the disc. Thus the disc sensilla can be interpreted as discrete temperature reading points. The resulting pattern of stimulated/deactivated sensilla, therefore, could provide the flying beetle with spatiotemporal information about its current position relative to an IR source. Possible biomimetic perspectives of the findings are discussed.