Results 1 - 10 of 22908
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[en] We have developed the self-consistent mean rate approach that makes it possible to analytically solve the coagulation–fragmentation balance equations subject to the mass conservation constraint. The developed approach is not restricted to a specific form of the coagulation and fragmentation rates, thus being applicable to a variety of different coagulation–fragmentation processes. As an example of the practical applicability of the developed method we have calculated the aggregate size distribution and average aggregate diameter for the case of shear induced coagulation–fragmentation
[en] We discuss how electrical current wires and micromagnetic elements can be used to trap or propagate paramagnetic beads, and consider their strengths and limitations. In particular, it is shown that the interactions can be effectively tuned by applying an external bias field. We demonstrate experimentally how to transport and structure a colloidal system using a domain wall, which could find use in microfluidic systems
[en] By flexible magnetic filament model its behavior under the simultaneous action of the shear flow and the magnetic field is investigated. It is found that for magnetoelastic numbers larger as the critical value, which depends on the shear rate, the periodic regime is established. For the values of the magnetoelastic number close to the critical the periodical regime is characterized by a rather slow development of the buckling instability due to the action of magnetic torques with the subsequent stage of the fast straightening of the filament. For the magnetoelastic numbers below the critical slightly bent shape of the filament orientated along the flow is established. The application of the results for the description of the viscoelasticity of the magnetorheological suspensions is discussed
[en] We present a multifractal description for Teichmüller flows. A key ingredient to do this is the Rauzy–Veech–Zorich reduction theory, which allows to treat the problem in the setting of suspension flows over subshifts. To perform the multifractal analysis we implement a thermodynamic formalism for suspension flows over countable alphabet subshifts a bit different from that developed by Barreira and Iommi.
[en] Measurements are reported of the plasma density in a highly ionized, thermally produced plasma containing a mixture of ions. The plasma densities in both binary and multi-component plasma mixtures are predicted for the case where the plasma potential is negative with respect to the wall potential. A floating electrostatic sheath boundary condition is assumed for the ion fluxes. There is agreement between the measured variation of the plasma density as a function of the plasma temperature and the predicted behaviour. (Auth.)
[en] The original BML model is extended by introducing extended sites, which can hold several vehicles at each time-step. Unexpectedly, the flow in the extended model sharply transits from free-flow to global jams, but the transition is not one-order in original BML model. And congestion in the extended model appears more easily. This can ascribe to the mixture of vehicles from different directions in one site, leading to the drop-off of the capacity of the site. Furthermore, the typical configuration of free flowing and global jams in the extended models is disorder, different from the regular structure in the original model.
[en] We investigate Lifshits-tail behaviour of the integrated density of states for a wide class of Schroedinger operators with positive random potentials. The setting includes alloy-type and Poissonian random potentials. The considered (single-site) impurity potentials f: Rd→[0,∞[ decay at infinity in an anisotropic way, for example, f(x1,x2)∼(|x1|α1+|x2|α2)-1 as vertical bar (x1,x2) vertical bar →∞. As is expected from the isotropic situation, there is a so-called quantum regime with Lifshits exponent d/2 if both α1 and α2 are big enough, and there is a so-called classical regime with Lifshits exponent depending on α1 and α2 if both are small. In addition to this we find two new regimes where the Lifshits exponent exhibits a mixture of quantum and classical behaviour. Moreover, the transition lines between these regimes depend in a nontrivial way on α1 and α2 simultaneously
[en] The structure of colloidal crystals, determined by scattering methods, is discussed. Charge-stabilized particles are considered briefly. The phase behaviour and crystal structures of 'hard-sphere' sterically-stabilized particles are described in more detail. Both one-component suspensions and binary mixtures of different-sized spheres are considered. (author). 9 refs.; 2 figs
[en] A theoretical model is developed to study the sedimentation characteristics of nanoscale colloidal suspensions (nanofluids). The influences of various deterministic and stochastic forcing parameters in the transport characteristics of the suspended nanoparticles are investigated by employing a Langevin formalism of particle transport. The role of collective particle interaction phenomena in the sedimentation of nanoparticles is analyzed by invoking the fundamental considerations of agglomeration-deagglomeration kinetics of the particulate phases. The model demonstrates the effect of particle volume fraction, particle size, and aggregate structure on the sedimentation velocity of the suspended nanoparticles. Predictions from the present model agree well with the experimental results reported in the literature. -- Highlights: → Sedimentation characteristics of nanoscale colloidal suspensions are studied. → Effect of particle aggregation and break-up is considered. → Nonmonotonic variation of sedimentation velocity with particle volume fraction is obtained. → Numerical results compare well with experimental data reported in the literature.
[en] A mixture of light and heavy spin-polarized fermionic atoms in an optical lattice is considered. Tunneling of the heavy atoms is neglected such that they are only subject to thermal fluctuations. This results in a complex interplay between light and heavy atoms caused by quantum tunneling of the light atoms. The distribution of the heavy atoms is studied. It can be described by an Ising-like distribution with a first-order transition from homogeneous to staggered order. The latter is caused by an effective nonlocal interaction due to quantum tunneling of light atoms. A second-order transition is also possible between an ordered and a disordered phase of heavy atoms