Mario Rodríguez Fernández

On undershoot in scalar discrete-time systems

We identify a class of asymptotically stable, strictly proper, non-minimum-phase, scalar discrete time systems whose step response is shown to exhibit undershoot a given number of times. The conditions governing this correspondence can be verified by inspection and have a simple expression in terms of the zero/pole locations of the underlying system. Both qualitative and quantitative aspects of the undershooting phenomenon are discussed, and a simple but non-trivial example is used to gain further insight into the main result of this paper.

An aseptic pilot bioreactor for solid substrate cultivation processes

Solid Substrate Cultivation processes (SSC) are characterised by the growth of microorganisms within a porous support without free water. This condition favors the development of filamentous fungi, given their unique capacity to colonise the interparticular spaces of solid matrices. In addition, the risk of bacterial contamination is reduced due to the low water activity (lower than 0 98) of the solid medium. Some interesting advantages of SSC processes compared with submerged cultivation are: higher productivities, lower operation costs and higher products concentration [1].

Crime prediction using patterns and context

Science fiction had anticipated the prediction of future occurrence of crimes. In fact, that prediction is actually possible. It can be done with some imprecision and by computer algorithms using available data from various sources. The prediction involves approximate time and risk maps of occurrence of certain type of felonies such as home burglaries, armed robberies and violent thefts. The police can then use this information for increasing their patrolling accordingly and thereby reducing the crime occurrence rate. We present a crime prediction solution developed for Chilean large cities. Its novel approach includes three independent software modules which make predictions based on different algorithms. The final prediction is the cooperative integration of the individual ones. The developed system has been tested on historical data and its performance has been considered acceptable for police field use. An interesting result is that the performance of each individual module is inferior to the joint performance, validating a hypothesis that different algorithms may exploit different features of the available data.