ON THE LENGTH EFFECT OF THE HEAT DISPERSION PARAMETERS

Considerable attention has been paid to the dispersion of heat in fixed beds passed by a flowing gas. This is best documented by ample experimental evidence and correlations available in the literature. However, the results of individual studies differ often significantly. As a possible cause of the discrepancies have been put forth various experimental techniques and data processing methods (Gunn, 1970; Froment, 1972; Li and Finlayson, 1977), particularly the use of different mathematical models.

As a fact of considerable significance, however, remains the dependence of results on the geometry of the experiment. All parameters of the pseudohomogeneous one- and two-dimensional models have been found to depend on the length of the bed (Li and Finlayson, 1977; De Wasch and Froment, 1972; Bunell el al., 1949; Calderbank and Pogorski, 1957), while their values invariably decrease with the increasing length. In contrast, neither of the existing models predicts such a dependence, nor is there a satisfactory explanation for the phenomenon at hand.

The aim of this work has been to carry out experimental measurements of the effective radial thermal conductivity in a fixed bed passed by flowing air and to analyze in detail the length dependence of the results. The experiments consisted of measurement of the steady state outlet temperature profiles corresponding to a radially distributed inlet profile.     

CATALYTIC OXIDATION OF CO ON CuO/Al2O3.I. REACTION RATE MODEL DISCRIMINATION

Carbon monoxide oxidation by pure oxygen on a porous catalyst of the type CuO on Al₂O₃ is studied in a laboratory differential recycle reactor. Reaction rate data obtained under atmospheric pressure and within the temperature range 135-165°C are used for reaction rate model evaluation. For a preliminary screening of models the method of quasi-linearized regression is proposed and successfully used. Box-Hill's procedure is applied for discrimination between the remaining small group of reaction rate models.     

Absolute extrema-seeking procedures †

A universal algorithm is presented in the paper which makes it possible to find out whether a given relative extremum of a scalar-valued function of a vector argument is also the absolute one and, if not, to find a point at which a relative extremum-seeking procedure can be restarted in order that a better relative extremum—i.e. one at which the given function takes a less, alternatively greater, value—may be obtained. Repeated application of the described procedure in combination with an arbitrary relative extremum-seeking procedure leads to determining the absolute extremum. The possibility of application to stochastic and integer programming problems is discussed.     

Cold trapped ions as quantum information processors

In this tutorial we review the physical implementation of quantum computing using a system of cold trapped ions. We discuss systematically all the aspects for making the implementation possible. Firstly, we go through the loading and confining of atomic ions in the linear Paul trap, then we describe the collective vibrational motion of trapped ions. Further, we discuss interactions of the ions with a laser beam. We treat the interactions in the travelling-wave and standing-wave configuration for dipole and quadrupole transitions. We review different types of laser cooling techniques associated with trapped ions. We address Doppler cooling, sideband cooling in and beyond the Lamb-Dicke limit, sympathetic cooling and laser cooling using electromagnetically induced transparency. After that we discuss the problem of state detection using the electron shelving method. Then quantum gates are described. We introduce single-qubit rotations, two-qubit controlled-NOT and multi-qubit controlled-NOT gates. We also comment on more advanced multiple-qubit logic gates. We describe how quantum logic networks may be used for the synthesis of arbitrary pure quantum states. Finally, we discuss the speed of quantum gates and we also give some numerical estimations for them. A discussion of dynamics on off-resonance transitions associated with a qualitative estimation of the weak-coupling regime is included in Appendix A and of the Lamb-Dicke regime in Appendix B.     

ELEMENTARY APPROACH TO THEORY OF FUNCTIONAL ORGANIZATION

The starting point of this paper is the well-known fact that the organization of a system in statistical physics can be expressed in terms of entropies, that is, as the difference between the entropies of the elements and the entropy of the whole. An analogous definition for goal-directed systems is proposed, in which a system is functionally organized if the success of the system toward attaining its goal exceeds the sum of the successes of the parts. This type of organization of goal-directed complex systems, referred to as functional, can be described within the framework of general systems theory by means of some basic concepts such as functional connection, cooperative dependence, and organizational function. A functional organization is defined as the actual manner in which the elements of a goal-directed complex system are functionally connected. A goal-directed complex system is characterized by an assembly of data from which certain quantitative measures of relevant properties of the functionally organized systems (e.g. their complexity and degree of organization) can be formed.     

Exact model matching,polynomial equation approach

A detailed analysis of the exact model matching problem in single-input—output linear systems is presented. The method of attack is based on polynomial algebra. The solvability conditions under various constraints are given and a simple design procedure is proposed. It consists in solving a linear polynomial equation which directly yields a compensator in a form suitable for realization.