Machine interference—a comparison of two patrolling methods

Tables of efficiency for a set of machines regularly patrolled by one operator have been produced. The theoretical basis of the tables has been described elsewhere. The numerical results show that unidirectional patrolling produces a small but consistent advantage over bi-directional patrolling, both in the case of manual repairs and automatic repairs which may not always be successful. This has implications for the design and layout of the machines on the factory floor. In addition, the tables can be used to determine the optimum number of machines to allocate to an operator.     

State-space formulae for the factorization of all-pass matrix functions

We consider the factorization of an all-pass matrix function E(s) using proper stable minimum-phase factors. Stale-space formulae for the stable minimum-phase factors of E(s) are derived (when they exist), as well as state-space formulae for the Wiener-Hopf factors. This is achieved using the state-space characterization of all-pass matrix functions given by Glover (1984) in conjunction with the results of Green and Anderson (1987).     

THERE AND THERE - A COLUMN OF NEWS

Abstract

The problem of when the Russians started to read the German cipher machine ENIGMA still remains unsolved. A Russian document presented recently in a history of the GRU in the time of the Great patriotic War offers a new light on the problem. In November 1942 the Russians were able to begin reading ENIGMA on a daily basis and were thinking about automating the process. We do not know if incorporating the GRU cryptanalysts in the parallel section of the NKVD helped in the brilliant defeat of the Germans during the “Uran” and “Saturn” operations at Stalingrad, but we suppose so. The Russian solution of the ENIGMA ciphers could be linked with the traitors working at Station X (Bletchley Park) and in Military Intelligence.