Research on the dynamic characteristics of the dynamic track stabilizer side searing
The dynamic characteristics of side bearing are one of the key factors for further study on the overall behaviour of the dynamic track stabilizer. The constitutive parameters of rubber spring were determined by the static experiment. Based on the parameters, the finite element model of side bearing was built and the reliability of side bearing model was verified by experiment. The vertical dynamic characteristics of side bearing were studied on the base of LS-DYNA. According to the analytical results, the dynamic characteristics of the side bearing spring constants and its internal damping are nonlinear under different compound of loads and frequencies. The conclusion can provide a theoretical basis to the optimal design of the side searing.
Non-Linear Behavior of a Rubber Isolator System Using Fractional Derivatives
A non-linear rubber isolator included in a dynamic system is examined where influences of dynamic amplitude and frequency are investigated through measurements and modeling. The frequency dependence of the isolator is modeled by a fractional calculus element while a frictional component accounts for its amplitude dependence. The model works in the time-domain and simulations of harmonic and non-harmonic motion are compared to measurements. Good agreement is obtained in a wide frequency and amplitude range for a freely oscillating one degree of freedom system, with the isolator acting as a coupling between exciting foundation and mass, and for a single isolator showing the typical amplitude dependence known as the Payne effect. The model is found to be superior to the commonly applied Kelvin–Voigt element in modeling the dynamic isolator properties.
Denitrification of PVA-immobilized denitrifying photosynthetic bacterium, Rhodobacter sphaeroides
Abstract A newly isolated denitrifying strain, Rhodobacter sphaeroides NII2 was immobilized in polyvinyl alcohol (PVA) gel, and the properties of the cells in the gel were examined. The immobilized cells had low or almost no denitrification activity, but the cells were activated by incubation in light with culture medium for denitrification containing 0.5% nitrate and no other nitrogen source. Cells grown in the dark were activated by incubation at an earlier stage and to a higher rate than the light-grown cells. The activation was markedly enhanced in the PVA gel with a low cell concentration. The immobilized cells consumed nitrate with a temporary accumulation of NO 2 and evolved nitrogen gas. The immobilized cells could use various organic compounds as electron donors for denitrification. Thus, the immobilized cells were applied to a continuous treatment of synthetic wastewater using an aparatus devised by this laboratory. The results showed an efficient removal of NO 3 -N from the test water.