Rapid decompression of pressurized aircraft fuselages

A methodology for determining compartment pressures at any point during a rapid decompression of a pressurized aircraft fuselage is presented. The approach takes into consideration the mass and mass moment of inertia of panels and doors through which pressurized air must pass. Failure to consider vent panel mass is shown to severely underestimate the pressure differential across partitions separating compartments during a rapid-decompression event.     

Comparing the rheology of native spider and silkworm spinning dope

Silk production has evolved to be energetically efficient and functionally optimized, yielding a material that can outperform most industrial fibres, particularly in toughness. Spider silk has hitherto defied all attempts at reproduction, despite advances in our understanding of the molecular mechanisms behind its superb mechanical properties. Spun fibres, natural and man-made, rely on the extrusion process to facilitate molecular orientation and bonding. Hence a full understanding of the flow characteristics of native spinning feedstock (dope) will be essential to translate natural spinning to artificial silk production. Here we show remarkable similarity between the rheologies for native spider-dragline and silkworm-cocoon silk, despite their independent evolution and substantial differences in protein structure. Surprisingly, both dopes behave like typical polymer melts. This observation opens the door to using polymer theory to clarify our general understanding of natural silks, despite the many specializations found in different animal species.     

Atomistic study of structural, elastic, electronic and thermal properties of perovskites Ba(Ti,Zr,Nb)O3

The full-potential linearized augmented plane waves (FP-LAPW) method based the on density functional theory (DFT) using the generalized gradient approximation (GGA) is applied to study the structural, mechanical, and electronic properties of BaTiO₃, BaZrO₃, and BaNbO₃ cubic perovskites. The quasi-harmonic Debye model, by means of total energy versus volume calculations obtained with the FP-LAPW method, is applied to study the thermal and vibrational effects. Predicted temperature and pressure effects on the structural parameters, thermal expansions, heat capacities, and Debye temperatures are determined from the non-equilibrium Gibbs functions.     

New Initiatives on Comparison of Whole-field Experimental and Numerical Results

Abstract: A simple approach to plot photoelastic fringes in grey scale and also in colour from finite element (FE) results is presented for better recognition and comparison with experiments. This requires proper identification of the plotting variable from FE results. For comparison with transmission photoelasticity, post-processing of principal stress difference is needed and for reflection photoelasticity the principal strain difference is to be used. The importance of the use of appropriate correction factors for comparison with reflection photoelastic results is emphasised. A newer approach to evaluate R _f for complicated geometries is indicated. Plotting of experimental fringes from finite elements is useful not only for validating the numerical model based on experiments but also for validating the experiments. To illustrate this, the problem of an interfacial crack in a bi-material Brazilian disc is discussed.     

Orientations of overdamped magnetic nanorod-gyroscopes

Overdamped magnetic nanorod-gyroscopes driven by a rotating magnetic field undergo a series of reorientations when sedimenting on top of a surface in a viscous liquid. By changing the amplitude and the rotation frequency of the driving magnetic field, the nanorod-gyroscope either synchronizes or desynchronizes with the field and rotates either around its long or short axis. The different regimes of motion are explained theoretically by coupling the nanorod-gyroscopes motion to the creeping flow equations of the surrounding fluid. It is shown that friction anisotropy plays an important role for the orientation of the nanorod-gyroscopes.     

Study of the hydrodynamic cycle of technical reactors by the use of a radioactive indicator

Conclusion The quantities defining the intensity of internal mixing in reactors with a volume of 76 and 186 liters (filled and empty) are determined by the method of introducing radioactive carbon dioxide C¹⁴O₂ as a tracer.It is shown that in the filled reactor when Re=12, the quantity Pe_L is close to the limiting value, equal to 2; the cycle in this reactor corresponds to ideal displacement.Change of temperature has no effect on mixing in the filled reactor.It is shown that in the empty reactor, when Re changes from 60 to 177 the parameter Pe_L remains almost constant and equal to 0.6. In this case, ideal displacement is not achieved in the empty reactors over the range of Re numbers investigated.Translated from Khimiya i Tekhnologiya Topliv i Masel, No. 11, pp. 44–46, November, 1972.     

New generation of hydrotreating catalysts

Translated from Khimiya i Tekhnologiya Topliv i Masel, No. 2, pp. 2–4, February, 1991.