ABSTRACT
In this paper, an intelligent scheme for detecting incipient defects in spur gears is presented. In fact, the study has been undertaken to determine these defects in a single propeller system of a small-sized unmanned helicopter. It is important to remark that although the study focused on this particular system, the obtained results could be extended to other systems known as AUVs (Autonomous Unmanned Vehicles), where the usage of polymer gears in the vehicle transmission is frequent. Few studies have been carried out on these kinds of gears. In this paper, an experimental platform has been adapted for the study and several samples have been prepared. Moreover, several vibration signals have been measured and their time-frequency characteristics have been taken as inputs to the diagnostic system. In fact, a diagnostic system based on an artificial intelligence strategy has been devised. Furthermore, techniques based on several paradigms of the Artificial Intelligence (Neural Networks, Fuzzy systems and Genetic Algorithms) have been applied altogether in order to design an efficient fault diagnostic system. A hybrid Genetic Neuro-Fuzzy system has been developed, where it is possible, at the final stage of the learning process, to express the fault diagnostic system as a set of fuzzy rules. Several trials have been carried out and satisfactory results have been achieved.
ABSTRACT
Optical encoders are sensors based on grating interference patterns. Tolerances inherent to the manufacturing process can induce errors in the position accuracy as the measurement signals stand apart from the ideal conditions. In case the encoder is working under vibrations, the oscillating movement of the scanning head is registered by the encoder system as a displacement, introducing an error into the counter to be added up to graduation, system and installation errors. Behavior improvement can be based on different techniques trying to compensate the error from measurement signals processing. In this work a new "ad hoc" methodology is presented to compensate the error of the encoder when is working under the influence of vibration. The methodology is based on fitting techniques to the Lissajous figure of the deteriorated measurement signals and the use of a look up table, giving as a result a compensation procedure in which a higher accuracy of the sensor is obtained.
ABSTRACT
Presentamos a una paciente de 26 años con obesidad mórbida, a la que realizamos colecistectomía profiláctica, biopsia hepática, gastroplastia vertical anillada con banda de polipropileno (7 cm de largo, adosada 1,5 cm, quedando una neoboca de 5,5 cm y 1,5 cm de ancho), sección del estómago vertical con GIA y sutura de refuerzo. Durante el postoperatorio presentó regurgitación, dificultad para la alimentación y vómitos alimentarios. Reingresó por un cuadro neurológico agudo: encefalopatía, oftalmoplejía, confusión mental y estupor. Se encuadra dentro del síndrome de Wernicke-Korsakoff, como consecuencia de déficit alimentario, disminución de tiamina y adelgazamiento rápido. Se instauró tratamiento con nutrición parenteral total y altas dosis de tiamina, con lo que la paciente se recuperó al poco tiempo de su reingreso en el hospital, siendo seguida en el Servicio de Neurología de este centro (AU)
