Surface waves in a periodic two-layered elastic half-space with the boundary normal to the layering

The paper deals with the problem of surface waves in a vertically layered elastic half-space. The transmitting medium is composed of periodically repeated two-constituent laminae, and its boundary is assumed to be normal to the layering. The problem is solved using an approximate model proposed by Wo?niak (Int J Eng Sci 25:483–499, 1987) and Matysiak and Wo?niak (Int J Eng Sci 25:549–559, 1987), which is referred to as the homogenized model with microlocal parameters. The velocity of the surface wave is obtained as a function of geometric and dynamic properties of the laminae. The variation of the surface wave velocity with respect to composite constituents is illustrated by numerical examples.     

Global and local parametric diagnosis of analog short‐channel CMOS circuits using homotopy‐simplicial algorithm

The paper offers an algorithm for local and global parametric diagnosis in nonlinear analog circuits, including both identification of the faulty parameters and determination their values. The algorithm exploits a nonlinear algebraic type test equations which may possess multiple solutions, corresponding to different sets of the parameters values which meet the test. To find the solutions, the homotopy concept is applied. Since the test equation is not given in explicit analytical form, the simplicial method is used to trace the homotopy path. The proposed approach can be applied to a broad class of analog circuits, including the complementary metal–oxide–semiconductor circuits fabricated in nanometer technology. The developed diagnostic procedure has been implemented in DELPHI, whereas the required by the algorithm repeated circuit analyses are carried out using IsSPICE 4 and both environments have been joined together. For illustration, two numerical examples are given. Copyright © 2013 John Wiley & Sons, Ltd.     

Examining the Effect of the Die Angle on Tool Load and Wear in the Extrusion Process

The tool durability is a crucial factor in each manufacturing process, and this also includes the extrusion process. Striving to achieve the higher product quality should be accompanied by a long-term tool life and production cost reduction. This article presents the comparative research of load and wear of die at various angles of working cone during the concurrent extrusion. The numerical calculations of a tool load during the concurrent extrusion were performed using the MSC MARC software using the finite element method (FEM). Archard model was used to determine and compare die wear. This model was implemented in the software using the FEM. The examined tool deformations and stress distribution were determined based on the performed analyses. The die wear depth at various working cone angles was determined. Properly shaped die has an effect on the extruded material properties, but also controls loads, elastic deformation, and the tool life.     

Application of kinetic methods in studying the defect concentrations and their mobility in transition metal oxides

A critical discussion of two new methods for investigating the concentration and mobility of point defects in the crystalline lattice of metal oxides is presented. These methods are based on kinetic measurements of metal oxidation in specialized conditions. Using the results obtained on the cobalt-cobaltous oxide-oxygen model system, it has been shown that both these methods lead to correct results being simultaneously more simple and accurate than the classical ones.     

Austenite formation of carbon and alloyed steels by intense argon and nitrogen plasma pulses: Role of carbon, chromium and nitrogen

Carbon and alloyed steels were subjected to transient treatment using high intensity argon and nitrogen plasma beams. In the former case the pulses induced only the heat effects whereas in the latter—the reactive atoms generated alloying effects. Austenitic phases have been studied with the use of conversion electron Mössbauer spectroscopy. Regularities between the alloying element contents (C, N, Cr) and austenitic phases have been established and discussed.     

Training of an artificial neural network in the diagnostic system of a technical object

The present paper covers the issue of training of an artificial neural network in an intelligent diagnostic system whose purpose is to evaluate repairable technical objects. The structure of the diagnostic system was characterized, and the measurement and diagnostic subsystems were described. An artificial neural network is an important element in an intelligent diagnostic subsystem. The structure, the algorithm, the organization of a neural network and the basic relations that describe its work were presented. The information presented in the form of the vectors of diagnostic signals, and their standard vectors constitute the primary information base used in “DIAG” computer program. Training of an artificial neural network is an important aspect that is presented in the paper. The issue concerning these problems is not presented in the literature. Training of a network was presented on the grounds of teaching vectors, which are determined in a diagnostic system in the process of a simulation of a specific state in the object examined. An example of training of a network was presented in a diagnostic system which evaluates a control system of the operation of a car engine. Appropriate connections were presented for the purpose of a qualitative assessment of the training process of a neural network.