Unbalanced-bridge Computational Techniques and Accuracy for Automated Multichannel Strain-measuring Systems

While much of the current literature and practice is concerned with balance-bridge strain measurements, this paper outlines a straightforward method for measuring strain using unbalanced-bridge techniques. Exploiting the performance and stability available in today's digital voltmeters and low-cost computers, it will be shown that the use of unbalanced bridges is well suited to automated strain measurements. The paper also presents a method for assessing the accuracy of a strain-measurement system by using the specifications of the individual components. Additionally, a comparison of accuracy for balanced and unbalanced conditions is included in this assessment.     

Radiant Heat Transfer Through an Aerosol Suspended in a Transparent Gas

The scattering of radiation by an aerosol in the cover-gas regionof a fast breeder nuclear reactor has been studied by meansof the equation of radiative transfer for a grey atmosphere.Some new results have been obtained in the form of an integralequation for the radiation intensity and heat flux. A variationalmethod is employed to obtain numerical results and the accuracyof an elementary theory based upon discrete ordinates is assessed.The variational approach leads to computationally useful andaccurate results for several quantities of practical interest.The interdisciplinary nature of the work is stressed by virtueof its close connection with neutron transport theory and rarefiedgas dynamics.     

COMPUTATION OF STRESS INTENSITY FACTORS BY THE SUB-REGION MIXED FINITE ELEMENT METHOD OF LINES

Based on the sub-region generalized variational principle,a sub-region mixed ver- sion of the newly-developed semi-analytical‘finite element method of lines’(FEMOL)is pro- posed in this paper for accurate and efficient computation of stress intensity factors(SIFs)of two-dimensional notches/cracks.The circular regions surrounding notch/crack tips are taken as the complementary energy region in which a number of leading terms of singular solutions for stresses are used,with the sought SIFs being among the unknown coefficients.The rest of the arbitrary domain is taken as the potential energy region in which FEMOL is applied to obtain approximate displacements.A mixed system of ordinary differential equations(ODEs) and al- gebraic equations is derived via the sub-region generalized variational principle.A singularity removal technique that eliminates the stress parameters from the mixed equation system even- tually yields a standard FEMOL ODE system,the solution of which is no longer singular and is simply and efficiently obtained using a standard general-purpose ODE solver.A number of numerical examples,including bi-material notches/cracks in anti-plane and plane elasticity,are given to show the generally excellent performance of the proposed method.     

Electromagnetic Diffraction in an Anisotropic Medium

The problem considered is that of the diffraction of an electromagneticplane by a half plane in an uniaxially anisotropic medium. Itis shown that the solution may be expressed formally in termsof the solutions of the Sommerfeld half-plane problems.     

MAGIC: The Design and Use of an Interactive Modelling Language for Mathematical Programming

The desirability of computer aids for the building as well asthe solving of Mathematical Programming models is argued. Ashort survey is given of some of the distinct approaches possiblein designing matrix generators/languages for such a role. Itis then suggested that the approach most suited to general modelsis to design a language close to widely used mathematical notation.The facilities needed in such a language are discussed and theimplementation using the MAGIC (MAtrix Generator InstructionConvertor) language described.