Mechanical Engineering

W T Norris,
MA, ScD, C.Eng, FIEE, FIMechE, Sen MIEEE, FCSD, FRSA
He is an electrical and mechanical engineer experienced broadly in electric power supply, utilisation and cognate industries. He was Head of Electrical Engineering at the Central Electricity Research Laboratories until 1986 engaged in trouble shooting and development activities. He continues consultancy in this area. He has engaged in research on the forefront of technology and tackled problems of more immediate practical nature particularly where careful analysis supported by insight is required. His continuing interests are in electricity supply systems and power plant performance, electromagnetic theory, health in electric and magnetic fields, superconductivity and in practical applications of and trouble shooting in electric power plant.
Signals & Systems Course Notes.
Mechanical Dynamics & Vibrations Course Notes.
2nd Year Control Engineering Course Notes.
nanohertz  an historical power oriented selection of reflections from the IEE Power Engineering Journal
In 1970 there appeared my paper Calculation of hysteresis losses in hard superconductors carrying a.c.: isolated conductors and edges of thin sheets, J Phys. D., 3,pp 486507, 1970.. A notable result was that at low currents the a.c. losses in a thin strip of hard superconductor are proportional to the fourth power of the current. The mathematics was given in abbreviated form and being asked recently how I arrived at some of the equations I was temporarily stumped, earlier notes having been lost. I give now more detail on the method used.
A particularly difficult definite integral had an integrand which included a parameter which was fixed for the integration. Taking the derivative of the integrand with respect to this parameter led to an "easy" integration. Integrating this result with regard to the parameter recovered the sought integral.
Hysteresis losses at a slit in a superconducting sheet. In the same 1970 paper I offered a solution to this calculational problem; the formula presented although showing the right fourth poer dependence on current was wrong giving results out by a factor of four at low currents and more at higher currents. The incorrectness was pointed out by Dr Majoros. By way of penance I redid the calculation which is now presented here in some detail identifying the point where I think that the mistake was made. With modern computing facilities I have also been able to give more graphical illustration of quantitative results.
Configuration and calibration of pickup coils for measurement
of ac loss in long superconductors,
Dr Yifeng Yang ( Institute of Cryogenics, University of Southampton),
and Miss
Elena Martínez (
Instituto de Ciencia de Materiales de Aragón, Zaragoza , Spain
and Institute of Cryogenics, University of Southampton) and
W. T. Norris.
This paper in the Journal of Applied Physics describes an experimental technique for the accurate measurement of losses in long of samples of superconductor subject to a transverse alternating magnetic field and carrying an alternating current
Note on Vibrating Annular Plates
with free outer and clamped inner radii. This Note reconciles the principal papers on the subject which, using different notations, might seem at first to contradict each other. A number of small corrections are suggested and some nondimensional numerical values are given for computing resonant frequencies of different modes of vibration of a plate. These might be used to check a computer progtramme.
Analysis of simple representations of rotating machines; synchronous and induction.
The treatment is of a machine with infinitely permeable rotor and stator and with sinusoidal surface current distributions
on rotor and stator surfaces. Two pole configurations.
Notes on a correction for Stokes formula for the viscous
drag on a sphere falling in a fluid. Stokes formula is satisfactory if the descent is sufficiently slow. If it is too fast there will be turbulence and Stokes formula will be give wrong results.
Nondimensional data from Prandtl are used for Reynolds numbers up to 100 to allow a better estimate of viscosity of a fluid from measurements of the terminal velocity of a sphere falling through the fluid than would be the case if Stokes formula were used alone.
This method relies on the principle of Dynamical Similarity which asserts that fluid flow can be scaled based on fluid properties, geometric size and velocities.The relationship between nondimensional quantities ( in this case Reynold's number and a Friction Factor ) are independent of the fluid properties, sphere size and velocities concerned. Though the nondimensional quantities themselves do depend on the physical quantities the relationship between them does not.
Notes on a high frequency performance of transformers. This paper coauthored and indeed almost all both developed and written by Dr Stefan Luff gives a new and extended development of theory of the propagation of surges in transformer windings including the secondary windings. The treatment is detailed and the novelty lies in the way the windings are described and the consequent analysis performed. The paper is entirely theoretical.
Notes on a Occasional papers on economics