Discrete Approach to PWL Analog Modeling in VHDL Environment

In this paper a discrete approach to analog modeling is presented. It is a functional-level, piecewise-linear (PWL) technique implemented in the VHDL environment. Since the models are based on some explicit formulas, fully behavioral architectural bodies have been proposed for them. Their most distinguishing features are discussed in detail. The models of practical circuits are illustrated with simulation results.     

Nonhomogeneos Boundary-Value Problem for Semilinear Hyperbolic Equation. Stability

We discuss the solvability of the nonhomogeneous boundary-value problem for the semilinear equation of the vibrating string x _tt (t, y) − Δx(t, y) + f(t, y, x(t, y)) = 0 in a bounded domain and a certain type of superlinear nonlinearity. To this end, we deduce new dual variational method. Next, we discuss the stability of solutions with respect to the boundary control and initial conditions.      

Multimethodical Approach and Generation of Sequence of Expressions for Acceleration of Repetitive Analysis of Analog Circuits

In this paper a concept of multimethodical program and a classification of Sequence of Expressions (SoE) for analog circuit analysis are discussed. It is shown that the proper selection of circuit analysis method as well as method of SoE generation enables the minimization of arithmetic operations during repetitive frequency and transient analysis of analog circuits.     

Optical networks—the electro-optic reality

A general overview of the current status and future trends in optical networking is given. Special attention is given to the coexistence of optical and electronic technologies in telecommunications networks. After reviewing the advantages of both technologies, their use in different network areas is discussed. A critical survey of current and new transport technologies in optical core and metropolitan networks is given, including SDH/SONET and its enhancements, OTN, RPR, and Ethernet. The current status and prospects for photonic switching are briefly presented. The paper is concluded with an overview of the control plane for optical transport networks.     

Electrical and stability properties and ultrasonic microscope characterisation of low temperature co-fired ceramics resistors

This paper presents systematic investigations of electrical and stability properties of various low temperature co-fired ceramics (LTCC) resistors. One of the goals of this work was to check the compatibility of LTCC materials (tapes, resistive and conductive inks) from various manufacturers. Three commercially available green tapes and three LTCC resistor/conductor systems were examined. The resistive inks with 1 kΩ/sq. nominal sheet resistance were used. Buried (inside) and surface resistors were laminated and fired according to the tape manufacturers’ recommendations. The influence of dimensional effect on sheet resistance and hot temperature coefficient of resistance, the temperature dependence of resistance in a wide temperature range (from −180°C to +130°C), long-term stability of thermally aged as-fired resistors (150°C, 500 h) and durability to high-voltage micro- or nanosecond pulses (50 ns pulses with 4000 V/mm maximum electric field or 10 μs ones with 700–1000 V/mm electrical field) were carried out for electrical and stability characterisation of LTCC resistors. Non-destructive scanning acoustic microscope diagnostics was applied for structure investigation and estimation of lamination and cofiring process quality of buried LTCC resistors.     

The EuQoS system: a solution for QoS routing in heterogeneous networks [Quality of Service based Routing Algorithms for Heterogeneous Networks]

EuQoS is the acronym for "end-to-end quality of service support over heterogeneous networks", which is a European research project aimed at building an entire QoS framework, addressing all the relevant network layers, protocols, and technologies. This framework, which includes the most common access networks (xDSL, UMTS, WiFi, and LAN) is being prototyped and tested in a multidomain scenario throughout Europe, composing what we call the EuQoS system. In this article we present the novel QoS routing mechanisms that are being developed and evaluated in the framework of this project. The preliminary performance results validate the design choices of the EuQoS system, and confirm the potential impact this project is likely to have in the near future     

Dielectric integrity of thin thermal oxides on silicon

The role of silicon dioxide layers in microelectronics and the importance of their integrity are undisputable. From passivating coatings and masking layers for diffusion to ultra-thin tunneling films — all the silicon technology could not exist without silicon dioxide. This review deals with some aspects of the integrity of thin silicon dioxide films for VLSI applications. The problems of dielectric strength and wear-out are considered from the point of view of their mechanisms, models, oxide processing dependence, testing, and measuring. A brief presentation of statistical approaches commonly applied to reliability topics is also included.     

Fracture toughness of structural components: influence of constraint

In this paper, in- and out-of-plane constraint are considered in the process of fracture toughness determination. A three parameter approach—J_IC, Q and T_z is utilized. The plane strain fracture toughness J_IC must be determined experimentally according to valid standards. It is the only quantity measured experimentally except for the classical uniaxial stress-strain curve determined for the material tested. Two additional parameters should be computed numerically using 2D and 3D FE analysis for the structural member which is actually analyzed. The T_z function is the generalized Poisson's ratio for elastic–plastic materials. The general model proposed allows for fracture toughness determination in two cases—when one fracture mechanism dominates the fracture process or two or more mechanisms are active simultaneously. To apply the model the fracture toughness for the particular fracture mechanisms should be known. In the paper simple models to determine these quantities are proposed both for cleavage and ductile fracture. In the latter case a distinction is made between fracture mechanisms along the shear lips and in the central part of the specimen.     

A search for optimal acrylic carriers for immobilization of penicillin acylase

Acrylic carriers were obtained by aminolysis of nitrile or ester groups in copolymers or terpolymers synthesized from acrylonitrile, acrylic esters and divinylbenzene or ethylene dimethacrylate in the presence of a mixture of inert diluents. The influence of the supermolecular structure of these carriers, generated during the suspension polymerization by adding a mixture of inert diluents, on the carrier properties was observed. Acrylic carriers for immobilization of penicillin acylase should be obtained from either porous or ‘sol’-type copolymers which aquire after aminolysis the structure of expanded gel.     

X-ray scattering investigations of acrylonitrileethylene oxide block copolymers

Wide angle (WAXS) and small angle (SAXS) X-ray scattering studies are reported on block copolymers of acrylonitrile with ethylene oxide. A distinct structural similarity between the copolymers and acrylonitrile homopolymer has been found. Considerable porosity of the copolymers has been shown. The porosity very largely governs the scattering power. It was found that the pores are three dimensional “particles” (scattering exponent α = 4), probably with smooth surfaces (surface fractal dimension d_s = 2).