Research on Discrete Data Analysis of Vehicle Retread Tire Performance Based on Radial Stiffness Method

The retreaded tires of transportation vehicles often cause delamination and tearing of the tread and carcass due to the temperature rise of the tires. For the failure analysis and rational use of the retreaded tires, a steady-state thermal analysis model of the retreaded radial tires in the rolling state is established and carried out the temperature measurement test. On this basis, the numerical simulation, simulation calculation and experimental analysis of the thermal-structure coupling field are carried out, which truly reflects the thermal stress status of the retreaded tire.

Dynamical Renormalization Group for Mode-Coupling Field Theories with Solenoidal Constraint

The recent inflow of empirical data about the collective behaviour of strongly correlated biological systems has brought field theory and the renormalization group into the biophysical arena. Experiments on bird flocks and insect swarms show that social forces act on the particles’ velocity through the generator of its rotations, namely the spin, indicating that mode-coupling field theories are necessary to reproduce the correct dynamical behaviour. Unfortunately, a theory for three coupled fields—density, velocity and spin—has a prohibitive degree of intricacy. A simplifying path consists in getting rid of density fluctuations by studying incompressible systems. This requires imposing a solenoidal constraint on the primary field, an unsolved problem even for equilibrium mode-coupling theories. Here, we perform an equilibrium dynamic renormalization group analysis of a mode-coupling field theory subject to a solenoidal constraint; using the classification of Halperin and Hohenberg, we can dub this case as a solenoidal Model G. We demonstrate that the constraint produces a new vertex that mixes static and dynamical coupling constants, and that this vertex is essential to grant the closure of the renormalization group structure and the consistency of dynamics with statics. Interestingly, although the solenoidal constraint leads to a modification of the static universality class, we find that it does not change the dynamical universality class, a result that seems to represent an exception to the general rule that dynamical universality classes are narrower than static ones. Our results constitute a solid stepping stone in the admittedly large chasm towards developing an off-equilibrium mode-coupling theory of biological groups.

Catastrophe Mechanism of Stress-Fissure Coupling Field in Mining Close Distance Seams in Southwest China

For the sake of studying the catastrophe mechanism of stress-fissure coupling field in mining close distance seams in southwest China, a test working face in Guizhou province in southwest China is adopted and researched by the methods of numerical calculation and similar experiment. When the working face advances to 180 m in 4# coal seam in a similar experiment, the overlying rock breaks to the central base plate of Yulongshan limestone, and the conductive fractures run through the Changxing limestone karst cave and Yulongshan limestone karst cave. When the 1402 working face advances to 350 m, the top of vertical karst caves in the middle of the model produces extrusion damage, forming a penetrating water inrush passage. When the 1402 working face advances to 480 m, the top slab of the working face comes under periodic weighting with the short step. Besides, the mining of 9# coal seam starts after 4# coal seam in mining close distance seams. When the working face in 9# coal seam advances to 340 m in numerical simulation, the maximum opening of the overburden fractures is 51.16 mm. The fractures in the roof are mainly caused by the periodic breaking and falling of the basic roof, connected with the floor fractures of 4# coal seam. When the working face in 9# coal seam advances to 500 m, the maximum opening of the overburden fracture is 93.09 mm. Specifically, as the working face advances, the opening of fracture in the roof after collapse of the basic roof periodically is mainly greater than 5 mm, and the compaction closure is mainly 1 mm-5 mm. The fractures in the gob floor are mainly 0.1 mm-1 mm, and the fracture opening of the collapsed rock mass in the gob is mainly 1 mm-5 mm and greater than 5 mm. The karst caves in the overburden reduce the periodic weighting step of working face and play a guiding role in the direction of fracture development and water inflow passage formation. The karst caves are connected to surface waterfall holes and trap pits, and atmospheric precipitation recharges the water in the caves. The research results can be treated as an important basis for the prevention and treatment for water inrush disaster in mining close distance seams in the karst area of southwest China.

The controllable amplitude and shape of hyperfine spectra in a ladder-type three-level atomic system

We report experimentally the properties of the hyperfine spectra in [Formula: see text]–[Formula: see text]–[Formula: see text] transitions of [Formula: see text]Rb. When the frequency of the coupling field is fixed between [Formula: see text]–[Formula: see text] transition and the probe scans the [Formula: see text]–[Formula: see text] transitions, two-photon absorption (TPA) and electromagnetically induced transparent (EIT) peaks could be investigated simultaneously, and the amplitude of the peaks can be controlled by changing the temperature of rubidium atomic vapor cell and the probe field power. In particular, the probe field power plays a dual role in controlling the amplitude of the peaks. In the [Formula: see text]–[Formula: see text]–[Formula: see text] transitions with the open intermediate state [Formula: see text], with decrease of the coupling field power, our experimental results show a crossover from a convoluted line-shape to EIT when the probe is weak whereas a transformation from a convoluted line-shape to TPA with an enhanced probe power. Formation of the convoluted line-shape is explained by virtue of the dressed energy-level diagram.