Correlation between MgSiO3 phases and mechanical durability of steatite ceramics

The steatite ceramics are mostly used in electrotechnics. Although distinguished by their mechanical and electrical properties they are unstable. The desirable, high temperature protoenstatite phase inverses into magnesium metasilicate low-temperature form—clinoenstatite, even upon standing. In this work the steatite polymorphism was studied in relation with steatite mechanical properties and microstructure. It was find out that the stabilization of protoenstatite in steatite body is achievable by the development of small crystals, yet it is still not resistant to action of water what put in question its potential application as dental material.     

Natural convective heat-transfers from an isothermal horizontal hemispherical cavity

A simplified analytical solution, numerical calculations with the use of the FLUENT/UNS code and experimental studies of laminar free-convection heat transfer from an isothermal hemispherical cavity in unlimited space are presented. The analytical solution is based on an adaptation of the methods used for inclined isothermal plates. In the proposed solution, the control surface of the hemisphere was considered as a small inclined surface. Inclination of this surface was a function of azimuth angle. The results of theoretical analysis, numerical calculation and experimental procedure are presented in the Nusselt and Rayleigh number: relations Nu_D=0.296 Ra_D^1/4, Nu_D=0.340 Ra_D^1/4 and Nu_D=0.316 Ra_D^1/4 respectively. The comparison of theoretical and numerical solutions with experimental results presented in this paper shows good agreement.     

ISDN loop extension using a mid span amplifier

The 5·5 km range of the basic rate ISDN loop has been extended by using a negative impedance amplifier and by using a 2 wire/4 wire (2w/4w) amplifier. The negative impedance amplifier extends the range of the loop by 1·0 km, whereas the 2w/4w amplifier extends the range by 1·5 km at the expense of increased complexity. As part of the amplifer design, a resistor/capacitor network has been developed which closely matches the characteristic impedance of telephone cable. Error rate tests have been conducted using various lengths of cable and an operating ISDN line.     

Properties of TiNxfilms reactively sputtered in an argon-nitrogen atmosphere

The dependence of the resistivity and temperature coefficient of resistivity (TCR) of TiN_x films on nitrogen pressure is described. The partial nitrogen pressure was varied from 10^?5 Torr to 2×10^?4 Torr. The maximum value of the resistivity (216 μΩ cm) and the lowest negative value of TCR (?33ppmK^?1) were obtained in the nitrogen pressure range (2?4)×10^?5 Torr. The minimum value of the resistivity (44 μΩ cm) and the highest positive value of the TCR (1160 ppm K^-1 were obtained in the nitrogen pressure range (4?10)×10^?5 Torr. The influence of aging temperature up to 573 K on the resistance changes are shown. X-ray diffraction analysis indicated the presence of oriented or non-oriented TiN in these films.     

The influence of grinding process on forced vibration damping in headstock of grinding wheel of cylindrical grinder

The paper describes theoretical analysis of dynamics of system: machine–tool–workpiece for cylindrical plunge grinding. The functional as well as mathematical model of grinder equipped with hydrostatic bearing of grinding wheel spindle and hydrostatic slideways has been presented in the paper. Simulations based on that model allow qualitative investigation of grinding force characteristics and its influence on forced vibrations in grinder. Results of simulation supported the thesis, that grinding force significantly influences the forced vibration damping of headstock of grinding wheel.     

A unified approach to layout wirability

We consider the problem of wiring planar knock-knee mode layouts. We present a systematic approach to this problem and develop a unified framework that also applies to layouts using grids that are more general than the usual square grid, and determine all possible grids that satisfy some natural regularity criteria. We develop some specific techniques for wiring of layouts in the square grid. As one of the applications of these techniques, we give a simple characterization of two-layer wirability of an arbitrary layout.On leave from the Institute of Computer Science, Polish Academy of Sciences, P.O. Box 22, 00-901 Warsaw, Poland. W. Lipski tragically died on May 30, 1985.The work of F. P. Preparata was supported in part by the Semiconductor Research Corporation under Contract SRC RSCH 84-06-049.     

Statistical and signal‐based network traffic recognition for anomaly detection

In this paper, a framework for recognizing network traffic in order to detect anomalies is proposed. We propose to combine and correlate parameters from different layers in order to detect 0‐day attacks and reduce false positives. Moreover, we propose to combine statistical and signal‐based features. The major contribution of this paper is novel framework for network security based on the correlation approach as well as new signal‐based algorithm for intrusion detection on the basis of the Matching Pursuit (MP) algorithm. As to our best knowledge, we are the first to use MP for intrusion and anomaly detection in computer networks. In the presented experiments, we proved that our solution gives better results than intrusion detection based on discrete wavelet transform.     

Fuzzy linear regression based on Polynomial Neural Networks

In this study, we introduce an estimation approach to determine the parameters of the fuzzy linear regression model. The analytical solution to estimate the values of the parameters has been studied. The issue of negative spreads of fuzzy linear regression makes the problem to be NP complete. To deal with this problem, an iterative refinement of the model parameters based on the gradient decent optimization has been introduced.In the proposed approach, we use a hierarchical structure which is composed of dynamically accumulated simple nodes based on Polynomial Neural Networks the structure of which is very flexible.In this study, we proposed a new methodology of fuzzy linear regression based on the design method of Polynomial Neural Networks. Polynomial Neural Networks divide the complicated analytical approach to estimate the parameters of fuzzy linear regression into several simple analytic approaches.The fuzzy linear regression is implemented by Polynomial Neural Networks with fuzzy numbers which are formed by exploiting clustering and Particle Swarm Optimization. It is shown that the design strategy produces a model exhibiting sound performance.