Object-oriented software for sparse matrix compression is briefly presented. Two approaches to unsymmetric sparse matrix compression are investigated. The first determines row reordering using the ...sum of original and transposed matrix. The second method uses the product of original and transposed matrix. Both methods are comprehensively compared using assorted matrices derived from engineering applications. These tests prove that best results are obtained, practically always, with the aid of ‘summation’ method.
Linear equations solvers form the basis of the software for field analysis and synthesis. A new pivoted solver of banded unsymmetric linear equation systems has been introduced It limits the fill-in, ...preserves basic band structure and makes full use of allocated memory. Two new features of this solver include multiple pivoting and the threshold factor used for pivoting decision. The stability, or rather the solution precision, has been investigated based on the examples of classic ill-conditioned equation system (Hilbert) and quasi-random system with still more difficult conditioning characteristics. Comprehensive test results have been presented in the form of diagrams. They prove the overall efficiency of the new solvers and compare them favourably with the software from CLAPACK library.
The Brayton-Gustavson-Hatchel (BGH) method for solving stiff ordinary differential equations belongs to the group of backward difference formulas methods. Basic details of the BGH method are ...presented. A new implementation with original modifications is described. Special attention is paid to the reduction of operation count and improvement of error control. Two examples including mildly stiff and stiff equation systems prove spectacular superiority of the BGH method with respect to the classic Gear method. The software presented in this paper is scalable and has been ported without any problems from the PC/DOS platform to two UNIX environments.
Basic factors influencing the sensitivity of resistance sensors of magnetic field have been determined. The relation of these factors and sensor geometric form, taking into account the field ...non-uniformity, has been investigated numerically and experimentally. After introduction of new mathematical model of a sensor, the optimization for the two modes - for limited dissipated power and for limited supply voltage has been carried out. It has been concluded that for a given film thickness and a gap between the sensor paths (depending on the manufacturing technology) there exists an optimal value of a path width and an angle between the path and anisotropy axis. The sensor sensitivity reaches maximum in this optimum point.
This paper presents a new method for testing electrical steel sheet, based on measurements of the magnetic field distribution over the sheet surface. The tangential field value is measured with the ...aid of a permalloy magnetoresistive sensor. The field distribution is displayed in the form of a color map, hence the method is called "magnetovision". The repeatability of the maps is excellent. The most interesting new results of electrical steel investigations are presented. The system provides a versatile tool for non-destructive quality control and for the determination of the structural uniformity of electrical steel. Magnetovision, compared with other methods, seems to be especially useful for detecting the causes of steel quality deterioration.
The need for solving large linear equation systems with dense coefficient matrices arises, among other applications, in the magnetic field analysis of end regions in the electric machines. Presented ...algorithm solves dense equation systems efficiently and has been extensively used on CDC Cyber 70 computers. It features list-like structure of dynamically splitted and merged blocks of system coefficients and minimizes spectacularly communication with disc memory.
Large linear equation systems with DBBF coefficient matrices appear in finite element solutions of partial differential equations, if periodicity conditions are taken into account. Efficient ...algorithm for solution of such systems, implemented in extended Fortran on CDC computers from Cyber 70/170 series, introduces original block-indexed method to reduce input-output time in communication with disc memory. Program optimization is considered and performance data are presented.
A method for the automatic analysis of the magnetic field distributions at the surface of electrical steel sheets was tested. A magnetostrictive probe with eight Permalloy sensors was used. The ...results are presented in the form of a contour map on a VDU screen. The main design and development problems are discussed. Some details of the magnetovision system for testing steel sheets are presented.
A method for the automatic analysis of the magnetic field distributions at the surface of electrical steel sheets is presented. The results are presented in the form of a contour map on a VDU screen. ...A magnetoresistive probe with eight Permalloy sensors is used. The main design and development problems are described. Some details of the magnetovision system for testing steel sheets are presented.
