Semiprime rings with finite length W.R.T. an idempotent kernel functor

The purpose of this note is to show that the only idempotent kernel functor σ on Mod-R, whereR is a semiprime ring andR _R has finite σ-length, is the idempotent kernel functorZ corresponding to the Goldie torsion theory.     

Developments in operational research: R.W. Eglese and G.K. Rand (eds.) Pergamon, Oxford, 1984, vii + 110 pages, $20.00

A practical method of calculating the distribution of the number of customers in the single server queueing system with inhomogeneous arrival rate and discrete service time distribution is proposed. The system is formulated as an inhomogeneous Markov chain in discrete time, leading to recurrence relations for the state probabilities. The recurrence relations are then solved numerically. Various measures of performance, such as mean and variance of the number of customers in the system and virtual waiting time can be obtained from these results. Examples are presented to demonstrate the scope of the method, including time-dependent behaviour of homogeneous queues; cyclic behaviour of queues with cyclic arrival rates; and a previously published study of an airport runway in which the author had to resort to crude interpolation to obtain results. The method can be further extended to provide a reasonably accurate approximation for some systems with continuous distributions of service times.     

Robots,CAM and O.R.

Microelectronics have greatly influenced the nature of manufacturing technology and systems. New factories make growing use of microcomputers and microprocessors in robots, C.N.C. machine tools and flexible manufacturing systems. The result is an increasing trend towards fully integrated computer-based manufacturing systems. As a consequence, O.R. software has a newer, more direct role in the modern factory than ever before. Fully integrated CAM systems are implemented by multi-disciplinary teams of engineers and management scientists. The O.R. practitioner can make a major contribution, for example in layout optimisation and plant simulations.     

Bemerkungen zur Arbeit von R. Chicurel und E. W. Suppiger The Reflection Method in Elasticity and Bending of Plates (ZAMP15, 629, 1964)

Ohne Zusammenfassung