LINEARIZATION OF EMPIRICAL RHEOLOGICAL DATA FOR USE IN COMPOSITION CONTROL OF MULTICOMPONENT FOODSTUFFS

Abstract An empirical measure of viscosity, which is often far from being a linear function of composition, was used together with refractive index to build up a function which bears a linear relationship to the composition of tomato paste-water-sucrose mixtures. The new function can be used directly for rapid composition control by linear vector-vector transformation.     

Consumers' use of written product information

Two studies were conducted to investigate the predictive role of person-specific, product-specific, and situation-specific influences on the use of instruction manuals in the field of electrical consumer products. In a laboratory study, 42 participants were observed while putting a vacuum cleaner into operation. Situational primes (i.e., receiving a verbal cue that the packaging contains an instruction manual) increased the probability of the user manual being read. Additional verbal information that the manual contains information on energy-saving behaviours was especially motivating for persons with high environmental concern. Self-report data, collected on a wide range of products, suggest that product complexity is the best predictor of instruction manual use. In a second study with 30 participants, different positions of product labels were compared, i.e. placing the information on the packaging or directly onto the product. Information placed directly onto the product had a significantly higher influence on participants' actual behaviour than providing the same information on the packaging.     

Cognitive demands of collision avoidance in simulated ship control

The study examines the cognitive demands of collision avoidance under a range of maritime scenarios. Operators used a PC-based radar simulator to navigate set courses over 100 6-min trials varying in collision threat and traffic density. Corrective maneuvers were made through the application of standard navigation rules and by using two decision aids (target acquisition and test maneuver). Results showed widespread effects of collision threat in terms of decision aid use, subjective workload, and secondary task performance. Most notably, demand increased markedly over the course of emergency trials, in which collision threat resulted from rule violation by target vessels. The findings are discussed in terms of the comparison between predictable demands (requiring standard course changes) and those involving uncertainty about the others' intentions (involving more intensive monitoring and forced delays in corrective action). The study has relevance for the design of collision avoidance systems, specifically for the use of ecological displays.     

Application of iterative suboptimal strategies for improving adaptation transients in adaptive systems

Some solutions which involve iterative optimization techniques are given to improve adaptation transients in adaptive systems. Two suboptimal controllers are developed and applied to an equivalent discrete-time system valid for describing the behaviour of a recent adaptive control scheme when one of the (time-varying) parameters entering the adaptation algorithm varies within a closed domain admissible from a convergence point of view. The resulting suboptimal control strategies are translated into corrections of this parameter in order to recompute the adaptation algorithm over a finite horizon. Some numerical simulations illustrate the usefulness of the proposed scheme.