The diffusion of moisture in sorbent solids—I. Diffusion cell and pore diffusion

A complete theory of diffusion of absorbing gases in porous solids is developed. Both ordinary and thermal diffusion are considered. The thermodynamics of irreversible processes is used to derive the general flux equations.A new theoretical model of surface diffusion is presented. Moreover, the proper method of combining surface and gas-phase fluxes is established. The total flux in the pores is represented by a 5 parameter model, which includes the effects of (1) free (gaseous) diffusion, (2) Knudsen diffusion, and (3) surface diffusion.The design of a new diffusion cell is presented along with a stagewise method for analyzing results. The cell is unique in that specimens mounted in copper clad circuit board material permits nonisothermal as well as isothermal operation. Earlier designs were confined to isothermal operation due to mounting specimens in metallic materials such as brass and aluminum.     

Heat transfer in packed bed heat recuperators-II. The film coefficient for dry sorbent solids

An elaborate experimental set up is described that was used to measure the thermal expiration curves of heat recuperators, that had been constructed with guard heaters and vacuum insulation to minimize heat losses. A much more general model is used along with a precision numerical analysis technique to show that a film coefficient correlation of the Dittus-Boelter type did an excellent job of representing the results from 162 runs in which three feed gas temperatures, two flow rates, two particle size ranges, one bed diameter and five desciccants were used. For comparison sake the reported film coefficient correlation is finally assembled in a table along with others found in the literature.     

The non-molecular structure of solids

To sum up our argument then: It is shown, in the first place, that the arrangement of the atoms in certain crystals, as determined by the X-ray spectra, indicates definitely that in these crystals there is no molecular structure.In extending the argument to all solid matter it is pointed out, from the dependence of crystal form on chemical composition, from a consideration of the Dulong-Petit law and of the nature of cohesion, and from the evidence of X-rays as to certain crystals, that each atom in a solid oscillates about a definite position of stable equilibrium.From a further examination of the nature of cohesion and of the forces concerned in chemical combination and especially from the general relation found between the atomic heat of formation of a substance and its melting-point it is found that the forces holding the atoms in their positions of stable equilibrium are of the same nature and comparable in magnitude with the forces binding together a chemical molecule.It is seen further that the atoms in a solid are very close together so that they often come in contact. And, since an atom attracts equally all atoms of another kind which are in contact with it, an atom cannot remain combined for more than an infinitesimal interval with any other particular atom ordinary temperatures.Finally, it was shown that, since in the solid state each atom has three degrees of translational freedom and is strongly attracted by atoms other than those of its own “molecule,” it must, on the average, exert equal attractions on all the neighboring atoms.From this the conclusion is drawn that in the particular molecules cannot be definitely defined.When those properties of solid matter which have been explained by molecules are considered, nothing is found which indicates at all definitely a molecular structure.We feel justified in concluding, therefore, that the structure of solid matter is not molecular.     

煤层气产出水中高浓度Cl-和HC03-对活性氧化铝吸附F-的动力学影响

通过静态试验研究了高质量浓度Cl-(1000mg·L-1)和HCO3-(2000 mg·L-1)对活性氧化铝吸附F-(10 mg·L-1)的动力学特性影响.结果表明:高质量浓度Cl-使活性氧化铝吸附F-速率加快,吸附量增加;高质量浓度HCO3-有相反趋势.建议采用活性氧化铝吸附除氟法作为煤层气产出水F-净化工艺时,考虑高质量浓度Cl-和HCO3-效应.     

Transient analysis of three-phase power systems,part II

The difficulties encountered with symmetrical components, as discussed in Part I, B, are eliminated when Clarke components are used. It is possible to investigate transient phenomena in three-phase systems by studying single-phase networks with the transient analyzer.The basic relationships between the three-phase problem and its equivalent representation in Clarke components are established in the first section (C) of this paper. The last section (D) of this study contains the component-network connections and the switching arrangements which are representative of the more frequent types of disturbances in three-phase systems.     

Stabilization for multi-group coupled models with dispersal by feedback control based on discrete-time observations in diffusion part

In this paper, we study the almost surely stabilization for a class of unstable multi-group coupled models with dispersal (MGMs, in short) by feedback control design based on discrete-time observations in diffusion part. Specifically, we show that the corresponding stochastically controlled system is almost surely exponentially stable when the stochastic MGM is almost surely exponentially stable within a duration of time. Finally, an example is given to illustrate the obtained theoretical results.     

The international diffusion of new information technologies

The paper analyses the rate of the international diffusion of modems as well as ils structural determinants.This work can be considered a case study of the extent to which the adoption of a new technology system such as new information technologies differs internationally.The results of empirical analysis stress the systematic character of new information technologies and suggest that it may become a factor in widening the technological cap between followers and leaders on international markets.     

隐性知识的传播与共享

隐性知识传播与共享是企业获得持续优势的关键，本文基于隐性知识的特点对隐性知识传播障碍进行分析。探讨了促进企业隐性知识传播和共享的途径。