Discrimination and identification of dynamic catalytic reaction models via introduction of feedback

Linear and nonlinear feedback manipulations based on effluent concentration measurements from a catalytic CSTR are successfully used to discriminate between two rival models for catalytic N₂O decomposition. Introduction of feedback causes steady-state multiplicity and bifurcation to periodic solutions. Much greater differences between the alternative models are revealed by this approach than by steady-state and “transient response” methods. Limit cycles obtained with feedback have in some cases nonharmonic form near bifurcation which may be attributed to bifurcation phenomena of higher order than the usual Hopf case. The dynamic studies are systematically organized using a new “decrement diagram” technique which displays the influence of two feedback parameters on closed-loop system bifurcations.     

国产印制板数控钻铣床的发展思考

随着我国电子制造业和PCB行业的快速发展,对电子制造装备提出越来越高的要求,印制电路板数控钻铣床向着高速、高精度、高可靠性、智能化、灵活性化、集成化的发展趋势越来越明显,其平台体系更加开放,产品配套供应更加专业、标准,从中可以清楚地看出我国印制板数控钻铣床的问题和差距以及我国今后的基本发展思路。     

Non-Rigid Shape Comparison of Plane Curves in Images

A mathematical theory for establishing correspondences between curves and for non-rigid shape comparison is developed in this paper. The proposed correspondences, called bimorphisms, are more general than those obtained from one-to-one functions. Their topology is investigated in detail.A new criterion for non-rigid shape comparison using bimorphisms is also proposed. The criterion avoids many of the mathematical problems of previous approaches by comparing shapes non-rigidly from the bimorphism.Geometric invariants are calculated for curves whose shapes can be exactly matched with a bimorphism. The invariants are related to the concave and convex segments of a curve and provide justification for parsing the curve into such segments.     

An experimental K-analysis on the fatigue crack near the interface where plate thickness varies discontinuously —Thin to thick type

The characteristics of fatigue crack propagation behavior near the thickness interface were examined for 6061 T6 aluminium specimens. A series of thin to thick type various thickness specimens was prepared. Fatigue tests were performed under load control in tension-tension. Correction factor of the stress intensity factors (SIF) for various thickness specimens was introduced as the form of F(α, β) where α was a dimensionless crack length and β was the thickness ratio. These correction factors were determined experimentally by means of linear elastic fracture mechanics concepts.     

Interfacial area and liquid side mass transfer coefficient in trickle bed reactors operating with organic liquids

Interfacial area and liquid-side mass transfer coefficients measured in a 5cm diameter trickle-bed reactor operating with organic liquids are presented d_p≤ 2.4 mm and cylindrical catalyst of size 0.9 mm × 5 mm. A few data concern also 5.9 and 6.4 mm Raschig rings. Gas and liquid flowrates a Mass transfer parameters have been determined by the chemical technique using the carbamation of the reactants cyclohexylamine, monoethanolamine or die results obtained at low gas-liquid interaction with low liquid flowrate are reported for the ionic aqueous systems CO₂-NaOH and O₂-Na₂SO₃. The variation of the mass transfer data, the gas pressure drop and the liquid holdup with the gas and liquid flowrates show that there exists a strong connection between these parameters. This has led to correlate the with the liquid-solid friction factor within a $\text{+}$30% accuracy.     

Theory of mercury porosimetry hysteresis

Intrusion—extrusion hysteresis and energy conservation in mercury porosimetry can be explained thermodynamically. In a first intrusion—extrusion cycle, hysteresis is explained and work is shown to be conserved when the processes of mercury entrapment and contact angle changes are considered. In subsequent cycles, when mercury entrapment ceases, it can be shown that work is conserved and hysteresis can be explained by the use of the correct intrusion and extrusion contact angles.     

Sensitivity analysis of systems of differential and algebraic equations

Formulae are derived for parametric sensitivity analysis of mathematical mo dels consisting of sets of differential and algebraic equations. Such equations often arise in dynamic modeling of equilibrium stage processes, and in solution of partial differential equations via the numerical method of lines. These formulae can be used to efficiently produce the model sensitivity coefficients, simultaneously with the solution of the model.     

Thermodynamic limits on conversion of solar energy to work or stored energy—Effects of temperature, intensity and atmospheric conditions

For more than two decades the subject of thermodynamic limits on conversion of light to work and/or chemical energy via photovoltaic or photochemical processes has been of considerable interest. Three distinct approaches have been taken to the problem; however, all three have recently been shown to be equivalent and to give identical results. Most earlier calculations have been carried out using AMO or AM1.2 solar spectral distributions. In this paper, we use AM1.5 spectra and concentrate primarily on the effects of variation of atmospheric conditions on calculated power-conversion efficiencies. The conditions we examine are: absorber temperature, total solar intensity, air mass, ozone and water-vapor content of the atmosphere, and the turbidity and visibility of the atmosphere. In addition we have computed efficiencies for the diffuse component of global solar radiation as an approximation to turbid conditions. The results are displayed as plots of solar conversion efficiency vs. bandgap wavelength for each set of conditions. Conclusions are then drawn as to the important variants which can serve to guide the design of photochemical and/or photovoltaic systems for a given environment.     

Ternary diffusion formulation for diffusiophoresis

A ternary diffusion formulation for diffusiophoresis, the migration of a particle in a solute gradient, is suggested. The formulation, derived from irr contributions in the D₁₂ “cross-term” diffusivity. The ternary diffusion formulation allows both measurement of the magnitude of diffusioph transport situation. Measured coefficients of diffusiophoresis agree reasonably well with previous electrohydrodynamic theories.