Hysteresis effect in the nonlinear stability of towed wheels

In this paper the dynamics of towed elastic wheels are studied with the help of the brush tyre model. To calculate the lateral deformation of the contact patch centre-line distributed time-delay is taken into account for the rolling parts, whereas parabolic limits are used to determine the deformation in case of side-slip. After linear stability analysis of the rectilinear motion the limit cycles of the non-smooth time-delayed system are calculated with the method of numerical collocation. With the help of bifurcation diagrams it is demonstrated how the periodic orbits develop from the linear stability boundary in a structure characteristic of piecewise-smooth systems. Moreover, it is shown that the contact memory effect and the dry friction yield bistable parameter ranges besides the linearly unstable domains. Namely, for one particular towing velocity a stable equilibrium corresponding to straight-line motion and a stable periodic orbit coexist resulting a hysteresis effect in the stability of the straight-line motion.</jats:p

First description of hypospadias and inguinal bilateral cryptorchidism in mouflon (Ovis Gmelini Musimon) — short communication

A mouflon showing severe weight loss and cachexia was examined. The animal had horns and a male-like body frame but the preputial fur was missing. The scrotum was completely absent. Both testicles were located next to the inguinal canal under the skin, and appeared only slightly smaller than normal. The prepuce was located in a perianal position under the anus and it resembled a vulva. The penis was underdeveloped and curled up inside the prepuce like an enlarged clitoris. The bulbourethral region and the urinary bladder looked normal. The orifice of the urethra was located in its normal position, but the glans penis appeared deformed. Microscopic examination of the testicles revealed mild degeneration of the seminiferous tubules and a marked proliferation of the interstitial connective tissue with Leydig cells still present. There were no marked changes in the bulbar part of the penis but the apical part exhibited marked interstitial fibrosis. This is the first description of hypospadias and cryptorchidism in mouflon