Results 1 - 10 of 2615
Results 1 - 10 of 2615. Search took: 0.026 seconds
|Sort by: date | relevance|
[en] We investigate the transport of a deterministic Brownian particle theoretically, which moves in simple one-dimensional, symmetric periodic potentials under the influence of both a time periodic and a static biasing force. The physical system employed contains a friction coefficient that is speed-dependent. Within the tailored parameter regime, the absolute negative mobility, in which a particle can travel in the direction opposite to a constant applied force, is observed. This behavior is robust and can be maximized at two regimes upon variation of the characteristic factor of friction coefficient. Further analysis reveals that this uphill motion is subdiffusion in terms of localization (diffusion coefficient with the form at long times). We also have observed the non-trivially anomalous subdiffusion which is significantly deviated from the localization; whereas most of the downhill motion evolves chaotically, with the normal diffusion. (paper)
[en] The friction and wear properties of mesocarbon microbeads-based graphite and siliconized graphite were investigated. At loads of 20–60 N, the graphite had low friction coefficient (0.15–0.26), while had high wear rate (0.039–0.50 × 10−3 mm3/m). Siliconized graphite had higher friction coefficient (0.375–0.40), while at higher loads of 40 N and 60 N, it had lower wear rates (0.15 and 0.18 × 10−3 mm3/m respectively). The main wear of ploughing resulted in low wear rate for siliconized graphite
[en] Velocity of geo block, sliding down on an inclination plane, depends on frequency and amplitude of the vibrations, and inclination angle and friction coefficient as well. The relevant equations and formulas have been derived
[en] This work presents simulation results for the behaviour of different particles in a new magnetic-classifier (MAGCLA(TM)), which is capable of separating and classifying particles according to their magnetic susceptibilities. In a previous article the results for a blank simulation were reported. In this paper the blank simulation is compared with the results obtained for the variation of two of the main processing variables: friction coefficient, μ, and the radius of the particles, rpart, in the outcome results
[en] In recent years, poly(etheretherketone) (PEEK) has been used as a replacement for the metal used in knee prostheses due to its good biocompatibility, abrasion resistance and corrosion resistance. A tangential fretting experiment on the contact interface of the tibial component (PEEK) and the highly cross-linked polyethylene (XLPE) gasket is carried out, and medical Ti6Al4V is used as a comparison to PEEK. The results show that (1) replacing the metal with PEEK does not cause increased fretting wear. Therefore, in view of the numerous advantages of PEEK, it is advocated as a prosthetic implant material. (2) The friction coefficient between the contact surfaces of PEEK and XLPE increases with an increase in the micromotion amplitude and decreases with an increase in the normal load. (3) The wear quality of fretting increases with an increase in the micromotion amplitude, normal load and number of cycles. (4) Wear occurs mainly on the edge of the contact surface, and the wear mechanism is adhesive wear and abrasive wear. (paper)
[en] For the undamped Kepler potential the lack of precession has historically been understood in terms of the Runge-Lenz symmetry. For the damped Kepler problem this result may be understood in terms of the generalization of Poisson structure to damped systems suggested recently by Tarasov (2005 J. Phys. A: Math. Gen. 38 2145). In this generalized algebraic structure the orbit-averaged Runge-Lenz vector remains a constant in the linearly damped Kepler problem to leading order in the damping coefficient. Beyond Kepler, we prove that, for any potential proportional to a power of the radius, the orbit shape and precession angle remain constant to leading order in the linear friction coefficient
[en] With the quantum diffusion approach, the probability of passing through the parabolic barrier and the quasistationary thermal decay rate from a metastable state are examined in the limit of linear coupling both in momentum and in coordinate between a collective subsystem and the environment. An increase of passing probability with friction coefficient is demonstrated to occur at subbarrier energies.
[en] The rheological properties of magnetic powders (MPs) excited by magnetic fields under parallel-plate shear were experimentally studied. The results showed that the shear stress increased with increasing magnetic field strength and volume fraction. It was also influenced by the plate gap distance, and was independent of the shear rate. The shear stress could be ascribed to the contributions of magnetic force and friction force, dominated by the normal force, the shear strain and the friction coefficient. The ratio of shear stress to normal stress, a form of friction coefficient, was influenced by volume fraction, magnetic field strength and gap distance. These results provide a better understanding of the mechanisms of magnetic field excited magnetic powders under parallel-plate shear. (paper)
[en] We present friction characteristics of sliding textured silicon surfaces at the submicrometre scale. A two-dimensional submicrometre dimple array on the Si surface is fabricated by femtosecond laser processing. Direct femtosecond laser nano-structuring of the Si (1 0 0) substrate by polystyrene particle-assisted near-field enhancement is used. In the investigated hole diameter domain from 229 to 548 nm, an increase in the friction coefficient with the decrease in the hole size is found experimentally. The fabricated submicrometre dimples act evidently as lubricant reservoirs to supply lubricants and traps to capture wear debris. The fluctuation of the friction coefficient is also increased by reducing the dimple size. The lowest friction coefficient of 1.41 x 10-2 is achieved with the dimple array having a diameter of about 550 nm. This value is 2.6 times lower than that of non-structured substrates
[en] Stick-slip dynamics during nanoscratching is investigated for the Ni62Nb38 metallic glass. Detrended fluctuation analysis is introduced to explore the influence of loading force on the temporal scaling and stick-slip behavior. The self-similar characteristics and complexity in the temporal scale of the lateral force signal are investigated. A modified Cauchy class model is used for the stochastic stick-slip process, which connects the fractal dimension and the Hurst exponent and features the positive correlation process. The confidence intervals of the differential friction coefficient at different loading forces elucidate the inhomogeneous (and homogeneous) shear-branching processes during the nanoscratching process.