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1.
Surface texturing has been recognized as an effective means to improve the tribological performances of sliding surfaces. Usually, generation additional hydrodynamic pressure to increase the load carrying capacity is regarded as the most significant effect of surface texture. In the case of silicon carbide sliding against identical material in water, the experimental results indicate that surface texture is also helpful to improve the running-in progress to smooth the contact surfaces, showing another reason to result in low friction. Based on the consideration of enhancing the generation of hydrodynamic pressure and improving running-in progress, a surface texture pattern, which was combined with large (circle, 350 μm in diameter) and small (rectangular, 40 μm in length) dimples, was designed to maximize the texture effect on the load carrying capacity of SiC surfaces sliding in water. The friction coefficient of such textured surface was evaluated and compared with that of untextured and those only with large or small dimples only. The friction reduction mechanisms of the patterns with different dimples in size are discussed. 相似文献
2.
Z.G. Xiao R.J. HuH.Y. Wu G.M. JinZ.Y. Li L.M. DuanH.W. Wang B.G. ZhangS.F. Wang Z.Y. WeiH.S. Xu Y.T. ZhuS.L. Li F. FuX.H. Yuan Z.Q. Feng 《Physics letters. [Part B]》2006
The inclusive reduced velocity correlation functions of the intermediate mass fragments were measured in the reactions of 36Ar + 112,124Sn at 35 MeV/u. The anti-correlation is observed to be stronger in 36Ar + 124Sn system than that in 36Ar + 112Sn. The difference of the correlation functions between the two reactions is mainly contributed by the particle pairs with high momenta. A three body Coulomb repulsive trajectory model is employed to calculate the emission time scale of the IMFs for the two systems. The time scale is 150 fm/c in 36Ar + 112Sn and 120 fm/c in the 36Ar + 124Sn, respectively. 相似文献
3.
C.J. MeiningH.A. Nickel A.B. Dzyubenko A. PetrouM. Furis D.R. Yakovlev B.D. McCombe 《Solid State Communications》2003,127(12):821-827
Many body effects contribute significantly to the energy states of electron-hole pairs confined in quantum wells in the presence of excess electrons. We present results of optically detected resonance spectroscopy of the internal transitions of photo-excited electron-hole pairs in the presence of excess electrons for GaAs QWs and CdTe QWs. Compared to the case of isolated negatively charged excitons, excess electrons produce a large blue shift of the internal transitions in modulation-doped GaAs quantum wells (QWs) for filling factor <2, and similar effects are found in CdTe QWs. For filling factor >2 no internal transitions are observed. These measurements demonstrate the strong effects of electron-electron correlations on the internal transitions of charged excitons in these quasi-2D systems and the importance of magnetic translation invariance. In the presence of excess electrons, the observed internal transitions are those of a magnetoplasmon bound to a mobile valence band hole. 相似文献
4.
M. Dubé C. Daneault V. Vuorinen M. Alava M. Rost 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,56(1):15-26
We investigate the structure and dynamics of the interface between
two immiscible liquids in a three-dimensional disordered porous
medium. We apply a phase-field model that includes explicitly
disorder and discuss both spontaneous and forced imbibition.
The structure of the interface is dominated by a length scale
ξ× which arises from liquid conservation. We further show
that disorder in the capillary and permeability act on different
length scales and give rise to different scalings and
structures of the interface properties. We conclude with a
range of applications. 相似文献
5.
Some results concerning the magnetic, electrical and microstructural properties of multilayer [FeCoBN/Si3N4]×n films in view of their utilization for manufacturing thin film magnetic inductors are presented. A comparison between the magnetic, electrical and structural properties of FeCoBN and [FeCoBN/Si3N4]×n thin films is also reported. The [FeCoBN/Si3N4]×n thin films with the thickness of the FeCoBN layers varied from 10 to 30 nm, exhibit good soft magnetic characteristics and high values for electrical resistivity such as Ms of 172–185 A m2/kg, Hc of 318–1433 A/m and ρ of 82–48×10−7 Ω m, respectively. These physical properties of the samples are discussed in relation with the microstructure of the multilayer system. 相似文献
6.
A. M. Dikandé 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,55(4):397-402
Excitations of the polaron types are investigated in the spin-1/2 quantum chain with XY exchange and Dzyaloshinsky-Moriya
interaction, both coupled to acoustic vibrations of the substrate lattice. The study is carried out via Jordan-Wigner transformation
with the help of which the spin chain is mapped onto a chain of spinless fermions. From the resulting effective fermion-lattice
Hamiltonian, the discrete equations of motion are derived. These equations are solved in the continuum limit for self-trapped
states near the bottom of the fermion spectrum interacting with long-wavelength acoustic lattice modes. The associate polaron
solution, which has a pulse shape, is shown to propagate bound to the induced lattice kink distortion by translation along
the chain at a constant velocity v. The pair can also experience an additional acceleration ϑ0 when the free fermion charge is excited above its groundstate. The polaron binding energy is strongly reduced, depending
quadratically on the ratio D/J of the Dzyaloshinsky-Moriya interaction strength D to the isotropic XY exchange interaction
J. It is also found that polaron parameters depend only on the XY spin-lattice coupling but not on the Dzyaloshinsky-Moriya
contribution. 相似文献
7.
B. Pedrini S. Wessel J. L. Gavilano H. R. Ott S. M. Kazakov J. Karpinski 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,55(3):219-228
We report results of susceptibility χ and 7Li NMR measurements on LiVSi2O6. The temperature dependence of the magnetic susceptibility χ(T) exhibits a broad maximum, typical for low-dimensional magnetic
systems. Quantitatively it is in agreement with the expectation for an S=1 spin chain, represented by the structural arrangement
of V ions.
The NMR results indicate antiferromagnetic ordering below TN=24 K. The intra- and interchain coupling J and Jp for LiVSi2O6, and also for its sister compounds LiVGe2O6, NaVSi2O6 and NaVGe2O6, are obtained via a modified random phase approximation which takes into account results of quantum Monte Carlo calculations.
While Jp is almost constant across the series, J varies by a factor of 5, decreasing with increasing lattice constant along the chain
direction. The comparison between experimental and theoretical susceptibility data suggests the presence of an easy-axis magnetic
anisotropy, which explains the formation of an energy gap in the magnetic excitation spectrum below TN, indicated by the variation of the NMR spin-lattice relaxation rate at T≪TN. 相似文献
8.
(Ti,Al)N Film on Normalized T8 Carbon Tool Steel Prepared by Pulsed High Energy Density Plasma Technique 下载免费PDF全文
Under optimized operating parameters, a hard and wear resistant (Ti,Al)N film is prepared on a normalized T8 carbon tool steel substrate by using pulsed high energy density plasma technique. Microstructure and composition of the film are analysed by x-ray diffraction, x-ray photoelectron spectroscopy, Auger electron spectroscopy and scanning electron microscopy. Hardness profile and tribological properties of the film are tested with nano- indenter and ring-on-ring wear tester, respectively. The tested results show that the microstructure of the film is dense ahd uniform and is mainly composed of (Ti,Al)N and A1N hard phases. A wide transition interface exists between the film and the normalized T8 carbon tool steel substrate. Thickness of the film is about lO00nm and mean hardness value of the film is about 26 GPa. Under dry sliding wear test conditions, relative wear resistance of the (Ti, Al)N film is approximately 9 times higher than that of the hardened T8 carbon tool steel reference sample. Meanwhile, the (Ti,Al)N film has low and stable friction coefficient compared with the hardened T8 carbon tool steel reference sample. 相似文献
9.
We study the chaotic dynamics of a periodically modulated Josephson junction with damping. The general solution of the first-order perturbed equation is constructed by using the direct perturbation technique. It is theoretically found that the boundedness conditions of the general solution contain the Melnikov chaotic criterion. When the perturbation conditions cannot be satisfied, numerical simulations demonstrate that the system can step into chaos through a period doubling route with the increase of the amplitude of the modulating term. Regulating specific parameters can effectively suppress the chaos. 相似文献
10.
S. Mahdavifar 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,59(3):285-289
We have studied the behavior of the energy gap of the 1D AF
spin-
XXZ model in a transverse magnetic field (h)
using the exact diagonalization technique. The ground state phase
diagram consists of two spin-flop and paramagnetic phases. Using a
modified finite-size scaling approach, we have computed the
critical exponent of the energy gap in the vicinity of the
critical transverse field hc(Δ). Our numerical results
confirm that the continuous phase transition from the spin-flop
phase to the paramagnetic one is in the universality class of the
Ising model in the transverse field (ITF). By applying conformal
estimates of a small perturbation (h≪1), we have also
justified our numerical results. 相似文献