On the road: travelling salesmen and experiences of mobility in Britain before 1939

Mobility has been a significant influence in the formation of identities for individuals and for certain occupations. Recent studies emphasises the associations of mobility with a sense of autonomy and personal freedom. This article explores the implications of mobility for a particular occupation, commercial travellers or travelling salesmen during the nineteenth and early twentieth centuries. It assess the changing duration and life on the road and the impact of new forms of transport, from horseback to motor car. Mobility fundamentally shaped travellers' daily experiences, the ways in which they perceived themselves and their public image

Mars: The Viking discoveries

An overview of the Viking Mars probe is presented. The Viking spacecraft is described and a brief history of the earlier observations and exploration of Mars is provided. A number of the Viking photographs of the Martian surface are presented and a discussion of the experiments Viking performed including a confirmation of the general theory of relativity are reported. Martian surface chemistry is discussed and experiments to study the weather on Mars are reported

Overparameterised controllers can reduce non-singular costs

By means of two examples we show that non-singular costs can been reduced for adaptive controllers by overparameterising the estimators. The examples are for scalar and second order systems respectively. In the second example the tuning function design and the overparameterised adaptive backstepping design are compared. In both cases a system is constructed for which the overparameterised design is superior w.r.t. a non-singular measure of transient performance

General Fast Sampling Theorems for Nonlinear Systems

This paper is concerned with the gap metric approach to controller discretisation problems for continuous-time nonlinear systems with disturbances in both input and output channels. The principal idea is to construct a discrete controller based on a given stabilizing continuous time controller via a fast sampling and hold procedure and to calculate the gap between the two controllers. It is expected that, under general conditions, the computed gap depends on the discrete sample size and the faster the sample rate, the smaller the gap and, therefore, existing gap metric robust stability theorems can be applied to obtain both stability and performance results for the appropriately discretised controller. This is shown for the case of memoryless controllers and for a more general class of controllers specified by stable, causal operators. In both cases, both regional and global results are obtained under respective local and global incremental stability assumptions on the controllers

Interactive Management and Updating of Spatial Data Bases

The decision making process, whether for power plant siting, load forecasting or energy resource planning, invariably involves a blend of analytical methods and judgement. Management decisions can be improved by the implementation of techniques which permit an increased comprehension of results from analytical models. Even where analytical procedures are not required, decisions can be aided by improving the methods used to examine spatially and temporally variant data. How the use of computer aided planning (CAP) programs and the selection of a predominant data structure, can improve the decision making process is discussed