Cavitation erosion of some alloys manufactured on steel and iron surfaces by laser beam

Cavitation erosion resistance of structural carbon steel, corrosion resistant chromium steel and technical iron superficially processed by CO₂ laser beam were investigated. Various metallic powders had been alloyed on the surfaces of the samples and then subjected to cavitation at the rotating disc facility. Tests were carried out in the incubation period of the erosion. It was found that material of reduced ability to work hardening could not achieve optional resistance to cavitation, regardless of its hardness. Moreover, strong dependence of the increase in erosion resistance of the alloyed materials on the substrate was also observed. The best performance under the erosion conditions displayed the samples alloyed with AlNi and SiC or with Nb powders. In each case mentioned, high increase in surface hardness was achieved due to cavitation loading.     

Single-solute adsorption from dilute solutions on heterogeneous microporous solids

Adsorption from dilute solutions on heterogeneous microporous solids is discussed. Two equations corresponding to the exponential distribution of micropore volume are derived by applying the generalized integral equation introduced by Stoeckli. The utility of these equations for interpreting the experimental data available in, the literature is shown.     

新型铸造用酚醛树脂粘结剂的生产工艺

苯酚、苯基苯酚、尿素与甲醛的反应产物进一步与糖醇缩聚生成新型铸造用改性酚醛树脂粘结剂。该粘结剂具有粘结强度高、低氨、低粘度等优点。其工艺技术已应用于工业生产。     

Investigations of electrokinetic properties of dyed polyamide fibres

Changes of the electrokinetic flow intensity Q_v and the zeta potential for polyamide fibres colourless and dyed with Polan dyes were analyzed. Essential differences in determined quantities were found for fibres dyed with dyes of different steric structure.     

SOME REMARKS ON SURFACE FREE ENERGY OF POLISH COALS

On the basis of the studies concerning the determination of the surface free energy of Polish coals published earlier analyses of the equilibrium state of three-phase system were carried out. The three-phase systems were:

1) coal - liquid drop - air, 2) coal - water drop -air, 3) coal - water drop - hydrocarbon, 4) coal -hydrocarbon drop - water and 5) coal - air bubble -water.

Analysing the measured values of the contact angles in the systems studied the occurrence of a liquid film on the coal surface was taken into account. The surface free energy. of Polish coals results from both dispersion (T_s^d) and nondispersion (T_sⁿ) intermolecular interaction. A distinct relationship was found between the dispersion components of the surface free energy and coal ranks.     

Up- and Downlink Admission/Congestion Control and Maximal Load in Large Homogeneous CDMA Networks

This paper proposes scalable admission and congestion control schemes that allow each base station to decide independently of the others what set of voice users to serve and/or what bit rates to offer to elastic traffic users competing for bandwidth. These algorithms are primarily meant for large CDMA networks with a random but homogeneous user distribution. They take into account in an exact way the influence of geometry on the combination of inter-cell and intra-cell interferences as well as the existence of maximal power constraints of the base stations and users. We also study the load allowed by these schemes when the size of the network tends to infinity and the mean bit rate offered to elastic traffic users. By load, we mean here the number of voice users that each base station can serve.     

A new technique for the solution of the Saha equation

A new computational technique for solving the Saha equation, which calculates the ionization states of gases, is presented. The algorithm is safe, converges quickly and is simple to implement. Pseudocode of the program is given to assist such implementation. Accuracy checks are described. Limitations of the technique at high ionization are discussed.     

Proving properties of Pascal programs in MIZAR 2

Summary In this paper we present the so called natural semantics for a subset of Pascal programming language. A set of sentences of first order predicate calculus defines the meaning of the Pascal language constructs. The meaning of a specific program is defined separately by another set of sentences which can be generated automatically. Both these sets together constitute axiomatics of a theory, called the theory of a specific program. The axiomatics is built in such a way that its logical consequences describe all the computational processes defined by the program. Proofs of properties for two small programs are discussed in detail. These properties and their proofs are recorded in the MIZAR 2 language — a computer formalization of predicate calculus. MIZAR 2 proof checker was used to verify the proofs.     

Feature space mapping as a universal adaptive system

The most popular realizations of adaptive systems are based on the neural network type of algorithms, in particular feedforward multilayered perceptrons trained by backpropagation of error procedures. In this paper an alternative approach based on multidimensional separable localized functions centered at the data clusters is proposed. In comparison with the neural networks that use delocalized transfer functions this approach allows for full control of the basins of attractors of all stationary points. Slow learning procedures are replaced by the explicit construction of the landscape function followed by the optimization of adjustable parameters using gradient techniques or genetic algorithms. Retrieving information does not require searches in multidimensional subspaces but it is factorized into a series of one-dimensional searches. Feature Space Mapping is applicable to learning not only from facts but also from general laws and may be treated as a fuzzy expert system (neurofuzzy system). The number of nodes (fuzzy rules) is growing as the network creates new nodes for novel data but the search time is sublinear in the number of rules or data clusters stored. Such a system may work as a universal classificator, approximator and reasoning system. Examples of applications for the identification of spectra (classification), intelligent databases (association) and for the analysis of simple electrical circuits (expert system type) are given.     

Reordering,recrystallization and recovery behaviour of (Co0.78Fe0.22)3V as a function of the initial state of order

The ordering kinetics of the L1₂ alloy (Co_0.78Fe_0.22)₃V have been studied on annealing below the order-disorder transition temperature and starting from different initial conditions induced by different thermo-mechanical treatments. The results obtained are reported in two parts. In Part I, we have determined by means of dilatometric, resistometric and calorimetric analysis, the relevant temperatures and energies dissipated in the transformations, and how the rates are affected by the initial conditions and annealing temperatures. The variation of hardness and the long-range order parameter have also been measured. The results obtained suggest that the overall kinetics are dependent on the way in which ordering, recrystallization and recovery phenomena occur at different temperatures and on how they affect each other.