Drying of granules in vibrating suspended bed: Engineering simulation

Engineering algorithm for simulation and designing of a continuous convective drying apparatus serving for drying heat-stable and heat-labile granules in a vibratory fluidized bed (vibrating, suspended bed) was suggested. The algorithm was based on a joint use of mass and heat balance equations, empirical dependences, and comparison of technological parameters with parameters got by the mathematical simulation of dynamics in the vibratory fluidized bed of variable weight. For example, we suggested a calculation algorithm of technological parameters of drying the heat-stable zeolite granules in the vibrating suspended bed. The results for a unit cost of heat and moisture evaporation standards in 3-stage drying were compared with the same for pneumatic drying apparatus, with devices of the fluidized and vibratory fluidized beds, and with sublimation dryers known in industry.     

Concurrent simulation of multibody systems coupled with stress–strain and heat transfer solvers

In the present work multibody 3-axis truck vehicle model coupled with submodels of suspension bodies is considered. Coupling the main model with submodels allows to perform simulation of multibody dynamics and non-stationary heat conduction and stress distribution processes in bodies simultaneously. High efficiency of parallel simulation on computer cluster is achieved using developed software based on MPI library.     

Concerted motion of protons in hydrogen bonds of DNA-type molecules

We study the dynamical behavior of proton transfer in hydrogen bonds in the base pairs of double helices of the DNA type. Under the assumption that the elastic and tunnelling degrees of freedom may be coupled, we derive a nonlinear and nonlocal Schrödinger equation (NLNLS) that describes the concerted motion of the proton tunnelling. Rough estimates of the solutions to the NLNLS show an intimate interplay between the concerted tunnelling of protons and the symmetry of the double helix.     

Coupling between polarization, orientation, and chirality in smectic films formed by bent-shaped molecules

We formulate a simple Landau type model describing macroscopic behavior recently discovered in new smectic phases composed of achiral bent-shaped molecules. Films of such smectics exhibit three types of ordering related to dipole polarization, molecular tilt, and chirality. However, due to specific third-order coupling of the order parameters, these three symmetry-breaking types are not independent and this fact leads to specific domain structures that are observed in experiments.     

Selective sorption of water vapor from gas mixtures containing H<Subscript>2</Subscript>S,SO<Subscript>2</Subscript>, NO<Subscript>2</Subscript>, NO,and CO on KU-2 sulfonic styrene cation exchanger in different ion forms

Sorption of water vapor and some acid gases (H₂S, SO₂, NO₂, NO, and CO) on Ku-23-15/100 macroporous sulfonic cation exchanger in different ion forms and on commercial KSM silica gel and NaX artificial zeolite was studied under equilibrium and dynamic conditions. The equilibrium isotherms of water vapor sorption were measured for all the adsorbents examined. The mechanism of water sorption on the sulfonic cation exchanger was discussed.     

Cyclic multiple-robot scheduling with time-window constraints using a critical path approach

An automated production system is considered in which several robots are used for transporting parts between workstations following a given route in a carousel mode. The problem is to maximize the throughput rate. Extending previous works treating scheduling problems for a single robot, we consider a more realistic case in which workstations are served by multiple robots. A graph model of the production process is developed, making it possible to apply PERT–CPM solution techniques. The problem is proved to be solvable in polynomial time.     

Short-Lived Large-Amplitude Pulses in the Nonlinear Long-Wave Model Described by the Modified Korteweg–De Vries Equation

The appearance and disappearance of short-lived large-amplitude pulses in a nonlinear long wave model is studied in the framework of the modified Korteweg–de Vries equation. The major mechanism of such wave generation is modulational instability leading to the generation and interaction of the breathers. The properties of breathers are studied both within the modified Korteweg–de Vries equation, and also within the nonlinear Schrödinger equations derived by an asymptotic reduction from the modified Korteweg–de Vries for weakly nonlinear wave packets. The associated spectral problems (AKNS or Zakharov-Shabat) of the inverse-scattering transform technique also are utilized. Wave formation due to this modulational instability is investigated for localized and for periodic disturbances. Nonlinear-dispersive focusing is identified as a possible mechanism for the formation of anomalously large pulses.     

Effect of dipole forces on the structure of the liquid phases of DNA

The dipole-dipole contribution to the energy of the pair interaction between DNA molecules has been calculated and analyzed. Rigid fragments of DNA, i.e., of a length of about the persistent length, which have discrete dipole moments of base pairs, are considered. For a given distance between the centers of mass of molecules, the energy of the dipole-dipole interaction is a function of three angular variables; the angles ?₁ and ?₂ between the central dipoles of both molecules and the z axis passing through the centers of the molecules, as well as the angle ξ between long axes of the molecules, are taken as these variables. It is shown that the dipole energy has minima when the mutual orientation of the molecules satisfies one of the following conditions: (i) ?₁ = ?₂ = 0 or (ii) ?₁ = ?₂ = π. The cholesteric twist angle ξ can be both positive and negative in dependence on the type of the minimum. For realistic cholesteric dispersion parameters, the dipole energy is only slightly lower than the experimentally known binding energy of the molecules in dispersion. The results allow the assumption that the dipole forces significantly affect the structure and other properties of DNA suspensions; in particular, they can lead to nontrivial texture phenomena, biaxial correlation, and multistability.     

Variational principle in canonical variables,Weber transformation,and complete set of the local integrals of motion for dissipation-free magnetohydrodynamics

The intriguing problem of the “missing” MHD integrals of motion is solved in this paper; i.e., analogues of the Ertel, helicity, and vorticity invariants are obtained. The two latter have been discussed earlier in the literature only for specific cases, and the Ertel invariant is presented for the first time. The set of ideal MHD invariants obtained appears to be complete: to each hydrodynamic invariant corresponds its MHD generalization. These additional invariants are found by means of the fluid velocity decomposition based on its representation in terms of generalized potentials. This representation follows from the discussed variational principle in Hamiltonian (canonical) variables, and it naturally decomposes the velocity field into the sum of “hydrodynamic” and “ magnetic” parts. The “missing” local invariants are expressed in terms of the “ hydrodynamic” part of the velocity and therefore depend on the (nonunique) velocity decomposition; i.e., they are gauge-dependent. Nevertheless, the corresponding conserved integral quantities can be made decomposition-independent by the appropriate choice of the initial conditions for the generalized potentials. It is also shown that the Weber transformation of MHD equations (partial integration of the MHD equations) leads to the velocity representation coinciding with that following from the variational principle with constraints. The necessity of exploiting the complete form of the velocity representation in order to deal with general-type MHD flows (nonbarotropic, rotational, and with all possible types of breaks as well) in terms of single-valued potentials is also under discussion. The new basic invariants found allow one to widen the set of the local invariants on the basis of the well-known recursion procedure.