Artículos de conferencia

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Reversibility of an electrical correlate to the process of learning
(1966) Luco Valenzuela, Joaquín; Aranda Coddou, Luis
Physiological disorders of pears in relation with nutrition
(INTERNATIONAL SOCIETY HORTICULTURAL SCIENCE, 1994) Rodriguez Gil, G. F.; Araos Henriquez, Joaquin Esteban; Ramos Vera, Cristian; Zoffoli Guerra Juan Pablo; Sugar, D
CNC control of a laser cutting machine
(IEEE, 1994) Chiang Sánchez, Luciano Eduardo; Ramos Grez, Jorge
This article describes the design and construction of a low power laser cutting machine with three degrees of freedom for applications such as wood, textile fabrics and the like. An available 10 Watt laser gun is used to provide the cutting mechanism. The results show that such a machine is feasible at a reasonable cost for applications where speed and repeatability are more important than high precision and power.<>
Effectiveness and mode of action of gibberellic acid on grape berry thinning
(AMERICAN SOCIETY ENOLOGY & VITICULTURE, 1994) Gil, GF; Rivera, M; Varas, F; Zoffoli Guerra, Juan Pablo; Rantz, JM
Four trials were conducted to determine the influence of gibberellic acid on fruit set and cluster compactness of Flame Seedless and Thompson Seedless grapes. Spraying GA(3) at bloom time to the canopy of Flame Seedless (8 mg/L) and Thompson Seedless (15 mg/L) resulted in loose clusters due to rachis elongation. Spraying before bloom increased number of berries in spite of decreased pollen germination. In Flame Seedless, shoot pinching alone seven days before full bloom (DBFB) increased berry number per cluster. Shoot pinching combined with GA(3) to clusters at bloom time increased the number of berries in Thompson Seedless. Defoliation followed by GA(3) to the entire shoot, apex, or cluster decreased the berry set of both cultivars. In Thompson Seedless, GA(3) applied to the terminal half of the cluster or shoulder produced berry thinning in the basal non-treated half, while treatment to the cluster base reduced set on the top. GA(3)-treated shoulder halves increased the number of berries. The results support the idea that GA(3) acts as a thinning agent by inducing rachis elongation and stimulating competition among organs which reduces set when nutrients become limiting for berry growth.
ANTICHOLINERGIC THERAPY IN CYSTIC-FIBROSIS PATIENTS
(EDITIONS SCIENTIFIQUES ELSEVIER, 1995) Sánchez Díaz, Ignacio
Characteristics of a small plasma focus device
(IET, 1996) Favre Domínguez, Mario Benjamin; Silva, P.; Chuaqui, Hernán; Wyndham Hodder, Edmund Sydenham; Choi, P.; Dumitrescu-Zoita, C.
We report on experimental observations in PFP-I, a small 3.8 kJ plasma focus, which is operated in Hydrogen-Argon mixtures to investigate the effect of parameter modifications on the overall performance of the device. An extensive array of diagnostics is been used, which includes voltage and current probes in the external circuit, a novel small magnetic probes array located along the cathode rods, filtered PIN diodes located side and end on, and multi-pinhole X-ray camera. EX1ended operated range from below 0.2 Torr upwards has been achieved with the implementation of the auxiliary discharge circuit. Despite the low voltage and low energy operation, energetic beam formation has been observed at the time of the final compression, prior to disruption. Current sheath formation and evolution has been characterised using the magnetic probes array, in correlation with beam formation and plasma emission. Time integrated visible plasma spectroscopy is performed to investigate impurity effects on focus performance and plasma dynamics at the collapse phase.
Neural network model for maximum ozone concentration prediction
(1996) Acuña, Gonzalo; Jorquera, Héctor; Pérez, Ricardo
A neural network dynamic model was used for predicting maximum ozone (O3) concentration at Santiago de Chile. Learning and test data were collected during summer and springtime periods of 1990, 1992 and 1993. A neural network having O3 t, Tt+1 (maximum air temperature) and Tt as inputs for predicting O3 t+1 was chosen because of its low test error. This neural network model greatly reduces the error coming from a pure persistence model when applied to the generalization set of data (1994). Long-term predictions results confirm the good concordance obtained between the observed and forecasted values thus showing the adequacy of neural networks to model the dynamics of this complex environmental phenomena.
Time resolved observations of plasma evolution in the hollow cathode region of a transient hollow discharge
(1996) Favre Domínguez, Mario Benjamin; Zambra Yañez, Marcelo Cristian; Moreno Martinez, Jose Alberto; Chuaqui, F.; Wyndham Hodder, Edmund Sydenham; Choi, P.
It is known that in a transient hollow cathode discharge (THCD), the formation of a moving virtual anode in the A-K space is causally linked to the emission of high energy electron beams originated in the hollow cathode region (HCR). In this work we report on time and space resolved observations of the formation and evolution of plasma inside the HCR which are time correlated with ionization processes inside the A-K gap. The experiments have been performed in Hydrogen, at pressures between 50 to 500 mTorr, at 30 kV applied voltage. Capacitive probes are used to monitor ionization growth in the A-K gap, in conjunction with time and space resolved spectroscopic observations in the HCR. High energy electron beams are also measured. Stark broadening observations of the HÎ² line indicate that the electron density inside the HCR increases up to a few times 1015 cmâˆ’3 some time before breakdown in the A-K gap. This time is also related with the electron beam activity
Basic aspects of oviduct function
(PARTHENON PUBLISHING GROUP LTD, 1997) Croxatto, HB; Ortiz, ME; Villalon, M; Cardenas, H; Imarai, M; Hermoso, M; Velasquez, L; Orihuela, P; Coutifaris, C; Mastroianni, L
Assessment of photochemical pollution at Santiago, Chile
(1998) Jorquera, H.; Olguin, C.; Ossa, F.; Perez Correa, Jose Ricardo; Solar, I.; Encalada, O.
Prediction of water chemical properties in the cycle of a coal power plant using artificial neural networks
(IEEE, 1998) Sáez Hueichapan, Doris Andrea; Sanz-Bobi, M. A.; Cipriano, Aldo
Describes a systematic methodology based on artificial neural networks for model identification and its application to the prediction of water chemical properties under normal operation conditions in a power plant. The model obtained allows detection of incipient anomalies by comparison between the real and predicted values.
Nitric oxide synthase inhibitors accelerate eCG transport in the rat oviduct by enhancing oviductal smooth muscle activity.
(SOC STUDY REPRODUCTION, 1999) Villalon, M; Martinez, S; Viggiano, M; Franchi, AM; Herrero, MB; Ortiz, ME; Gimeno, M
Probing the inner part of protoplanetary disks with the VLTI.
(2000) Malbet, Fabien.; Lachaume, Regis; Monin, Jean-Louis.; Berger, Jean-Philippe.
A model of internal control may improve the response time of an automatic arterial pressure controller
(IEEE, 2000) Urzua Urzua, Jorge; Sauma Santis, Enzo Enrique; Cipriano, Aldo; Guarini Hermann, Marcelo Walter
A simplified model for the arterial pressure control system was implemented on a personal computer using Matlab Simulink(R). Model responses to variations of systemic vascular resistance were comparable to those predicted by physiology. Computer simulation suggested that including this model of the internal pressure control system within the design of an external controller would achieve better arterial pressure control and faster response than previous systems.
Regulation of smooth muscle activity in the oviduct by sex hormones
(CAMBRIDGE UNIV PRESS, 2000) Villalon, MJ; Martinez, S; Hermoso, M; Saez, JC
Transduction mechanisms associated with activation of P-1 and P-2 purinoceptors in oviductal ciliated cells: functional cross-talk between both pathways
(CAMBRIDGE UNIV PRESS, 2000) Barrera, N; Morales, B; Villalon, MJ
Predictive control with fuzzy characterization of percentage of solids, particle size and power demand for minerals grinding
(IEEE, 2001) Orchard, M.; Flores Moltedo, Andrés Ricardo; Munoz, C.; Cipriano, Aldo
The application of fuzzy predictive control to solve the regulatory problem in mineral grinding plants is considered. The controlled variables are percentage of solids, particle sizes and power demand and the manipulated variables are water and fresh ore flows. The controller uses linear multivariable models and the fuzzy characterization of the controlled variables, to calculate the manipulated variables. Simulation results under typical disturbances show a better performance compared with the conventional predictive control.
A model based fault detection and diagnosis system for rolling mill equipments
(IEEE, 2001) Orchard, M. C.; Cipriano, A. M.; Cipriano, Aldo; Viale, M.; Vigliocco, A.
In this paper, the implementation of a Model Based Fault Detection and Diagnosis System, that uses fuzzy logic to determinate the nature of the detected faults in rolling mill equipments is presented. The system is built with 4 components which work independently. An Identification module estimates the parameters of a continuous domain second order transfer function model for the process by analyzing the step response. A Predictive model module generates the controlled variable residual which is statistically analyzed in a Detection module. The results of the statistical analysis are fuzzified and processed in a Diagnosis module to determine detected fault's nature. The system is tested using real operation data of a main motor process in order to detect and classify abnormalities into Operation Point Change (OPC) or Process Fault (PF) alarms.
Cost effective vision system for mobile robots
(IEEE, 2002) Martin Aguirre, Juan Francisco; Chiang Sánchez, Luciano Eduardo
A Webcam-based vision system for performing image processing in real time in a restricted environment is presented. A color based image segmentation algorithm is the fundamental part of the system. Algorithm efficiency was very important due to hardware limitations. This led to a simple and cost-effective vision system that is able to detect and identify several mobile robots through successive frames. The main achievements of the presented system can be described as robust object detection under relative constant illumination and sufficient refresh rate at image processing to evaluate position and direction of movement of target objects with a rough idea of speed.
Properties of hot-spots in Plasma Focus discharges operating in Hydrogen-gas mixtures
(IEEE, 2002) Silva Zuñiga, Hector Patricio; Favre Domínguez, Mario
We have investigated the properties of hotspots formed in low energy Plasma Focus discharges operating in Hydrogen-Argon mixtures, at 140 kA current level. The results show that best conditions for reproducible and localized hotspot formation are obtained by adjusting the base pressure in such a way that the mass load allows the time of first radial collapse to coincide with peak current. When the Plasma Focus is operated with 20% Argon content, rather uniform hotspots, of 115 Âµm characteristic size and 300 eV characteristic temperature, are produced with a better than 80% reproducibility in their axial localization. A significant fraction of the radiation is emitted in the 3.2 to 3.88 keV region, corresponding to KÎ± emission from highly ionized Argon.

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