A BASIC MODEL OF INTERACTING SUBJECTS

Abstract

In studying the problem of interaction between subjects, an approach which allows us to define in an unambiguous way the concepts of symmetrical, complementary and parallel interaction is proposed. This approach makes use of a point of view within which it is possible to develop a rational model based only on some fundamental elements of set theory and mathematical logic

The model allows us to develop a probabilistic theory of change, the representation basis of which is furnished by the 16 basic set functions. The functions represent operations on two partially overlapping sets, which will be called the “worlds”, of interacting subjects.. Both an interaction test that allows a “measure” of the relation parameters and the preliminary results of a dyadic interaction experiment are presented

Some remarks can be made from the results of the present experiment and from other similar ones. Among these there are evidences that the symmetrical, complementary and parallel classes of interactions belong to the same logical level and represent only some possible interaction classes.     

Temporal evolution of the NDVI as an indicator of forest fire danger

This work presents a study of the possibility of estimating forest fire danger by means of the analysis of the temporal evolution of the Normalized Difference Vegetation Index (NDVI) Advanced Very High Resolution Radiometer (AVHRR). Images of Spain corresponding to areas of Valencia and Eastern Andalusia in 1993 have been used. The slope of the evolution curve of the NDVI is an indicator of water stress and it is used to estimate danger. Forested areas are previously selected using the NDVI integral in the period studied. In order to determine the reliability of the index, ground data measured by the Spanish National Forestry Service (ICONA) are available to us     

Minimal controllability for systems with delays†

In this paper we consider the problem of minimal controllability for a general class of linear spectrally controllable systems. We show that the smallest number of controls that are necessary in order that spectral controllability may hold depends only upon the matrices of the uncontrolled system and that it is equal to the smallest number of outputs necessary for the dual problem of ‘spectral observability’; moreover, any spectrally controllable system can be made minimally controllable by acting upon the control matrix only, and any spectrally observable system can be made minimally observable by acting upon the output matrix only. In the sequel this result is explained in the cases of the delayed systems and of some kind of generalized systems.     

Inhibitory effect of jasmonic acid and ethylene on epicotyl growth and bud induction in the maritime pine, <i>Pinus pinaster</i> Soland. in Ait

Two independent parameters, epicotyl height (cm) and number of induced buds were studied on Pinus pinaster explants to analyse the effects of three phytohormones (6-benzylaminopurine, jasmonic acid, ethylene) which were combined or not in 11 different treatments. Epicotyle length diminished significantly in relation to the control medium (medium without exogen phytohormones) in presence of jasmonic acid, 6-benzylaminopurine or Ethephon (which is converted to ethylene in plants) in any of treatments. Concentrations of 100 μM of jasmonic acid and Ethephon had a greater inhibitory effect than the treatments with 10 μM. In addition to that, jasmonic acid was a stronger inhibitor than Ethephon in any of the tried combinations. There were no significant differences between the control treatment and the treatments with only 10 μM of jasmonic acid or Ethephon. However, 10 μM 6-benzylaminopurine induced bud formation. The different combinations of 6-benzylaminopurine with jasmonic acid and Ethephon showed that concentrations of 10 to 100 μM did not affect the number of induced buds. Jasmonic acid had an inhibitory effect which Ethephon only showed when combined with 100 μM of jasmonic acid and 10 μM of 6-benzylaminopurine. Three response groups were defined by cluster analysis: group 1 produced the greatest mean number of buds (4 to 5) and a mean epicotyl growth of 1 to 1.5 cm; group 2 produced 2 to 4 buds and a mean growth of 0.5 to 1.2 cm; group 3 produced only one bud and a mean epicotyl length of 1.2 to 2 cm.     

Building models for crack propagation under fatigue loads: application to macrocrack growth

This paper deals with the problem of building crack growth models. First, some inconveniences of existing models are described. Next, a general methodology is presented starting by identifying the set of variables involved in the crack growth problem obtaining a minimum subset of dimensionless parameters with the help of the Buckingham theorem, and imposing some consistency and compatibility conditions in terms of functional equations. These functional equations, once solved, provide the subset of crack growth models satisfying the required deterministic and stochastic compatibility conditions, which, in addition to providing mean values of the crack sizes as a function of time, as alternative models do, also give densities of the crack sizes. The main elements required to build a crack growth model, such as the initial crack size distribution, the crack growth function and a loading effect function, have been identified. The methodology is illustrated with some examples, including crack growth for different load histories. Finally, some models proposed in the past are shown to satisfy these conditions and one numerical example is given.     

EVALUATION OF INSTRUMENTAL METHODS FOR FIRMNESS MEASUREMENT OF FRESH AND CANNED CLINGSTONE PEACHES

The firmness of fresh and canned clingstone peaches was investigated using blade extrusion, back extrusion, and shear-compression instruments. The three techniques yielded results which correlated well among themselves and to sensory evaluation of peach firmness. Results indicate that high vacuum flame sterilization yields a canned product which is closer in firmness to fresh peaches than is the conventionally retorted product.     

INDUCTION MOTOR FLUX RECONSTRUCTION VIA NEW REDUCED-ORDER STATE OBSERVER

ABSTRACT

In this paper a new type of the reduced-order time-varying state observer for voltage- and current-fed induction motor is presented. The observer error decreasing rate is arbitrarily formed by a suitable choice of the observer eigenvalues, which does not depend on the rotor speed. Stability of the observer is proved. Dynamical properties of such observers in various operating conditions of the drive system are analysed. Results are numerically verified by simulation.