Multi-sensor system using plastic optical fibers for intrinsically safe level measurements

A system for measuring liquid level in multiple tanks using optical fibe technology has been developed. Oil fiel service industry or any sector requiring liquid level measurements in flammabl atmospheres can be benefite from this intrinsically safe technology. The device used a single lens for the emitting and receiving fibe and it is based on amplitude variations as a function of the liquid distance and not in time of fligh or phase detection. Being the firs fiber-opti liquid level sensor with those characteristics for long ranges (>200 cm). A simple model to describe their behavior has been derived and tested on two prototypes. A Monte-Carlo method is used to fi the experimental data and obtain the model parameters. High accuracy between experimental data and fitte curve is obtained. The prototypes have a good linearity, better than 1.5% FS (full scale). Sensor heads are made of plastic optical fiber (POF) that are easy to handle, flexible and economical. They are excited by 650 nm lasers, housed in ST-connectors to obtain compact and rough prototypes. Optical multiplexing is used to increase the measuring safety area. Frequency division multiplexing is used to address each sensor head. A discussion about the influenc of tilts and aberrations is also included.Publicad

Inter and intrasubject domain issues on the content of epistemological conceptions in university teachers

El presente trabajo estudia las concepciones epistemológicas de docentes universitarios desde la perspectiva de las teorías implícitas. Se analiza de qué manera intervienen en las concepciones: (a) la disciplina de formación que poseen (cuestiones de dominio intersujeto) y (b) el contexto escogido para indagar las concepciones (cuestiones de dominio intrasujeto). Se utilizó un diseño ex post facto prospectivo, recurriendo a dos cuestionarios de dilemas para indagar a los sujetos. Del análisis intrasujeto se concluye que las concepciones sobre conocimiento científico y las concepciones sobre enseñanza y aprendizaje no están relacionadas, excepto que unas y otras se hayan adoptado de manera explícita. El análisis intersujeto arrojó como resultado que la disciplina de formación de los docentes incide en el contenido de las concepcionesThis paper examines the epistemological conceptions of University professors from the perspective of implicit theories. We analyze how the following factors influence these conceptions: (a) the discipline of training them have (intersubject domain issues) and (b) the context chosen to investigate the conceptions (intrasubject domain issues). We used an ex post facto prospective design, using two questionnaires stating dilemmas to probe the participants. From the intrasubjecto analysis we can conclude that conceptions of scientific knowledge and ideas about teaching and learning are not related, except that they have been taken explicitly. Intersubject analysis results showed that the discipline of training of teachers affects the content of conceptionsO presente estudo analisa as concepções epistemológicas dos docentes universitários a partir da perspectiva das teorias implícitas. É analisada a forma em que intervém nas concepções: (a) a disciplina de formação que os professores têm (problemas de domínio intersujeito) e (b) o contexto escolhido para investigar as concepções (questões de domínio intrassujeito). Foi utilizado um desenho ex post facto prospectivo, aplicando dois questionários de dilemas para investigar aos participantes. Da análise intrassujeitos conclui-se que as concepções sobre conhecimento científico e sobre ensino e aprendizagem não estão relacionados, com exceção de que umas e outras tenham sido adotadas de maneira explícita. A análise intersujeito mostrou que a disciplina de formação dos docentes afeta o conteúdo das concepçõe

Ricardo Rojas y el factor estudiantil en la Fundación de la Universidad Nacional de Cuyo

Fil: Fontana de García, María B.

Multi-Sensor System For Level Measurements With Optical Fibres

A system for measuring liquid level in multiple tanks using optical fibre technology has been developed. The oil field service industry can benefit from this intrinsically safe technology. Plastic optical fibre (POF) sensor heads are excited by a 650 nm laser. Laser diodes are housed in ST connectors to obtain compact and rough prototypes and these connectors are also used in the fibre pigtails. Optical multiplexing is used to increase the measuring safety area. POF splitters and connectors are used to combine all the receiving sensor head fibres in a single one. Frequency division multiplexing is used to address each sensor head. The global system is controlled through a user friendly software application running in a PC connected to the system via an RS-232 port. A scalable prototype with a range greater than 2 meter, good linearity, better than 1.5% FS (full scale), high accuracy and resolution is developed using a unique lens to collimate and focus the light. Measurements are taken to validate the designs. Up to 8 sensor heads can be connected in the present implementation. But a greater number of sensors can be allocated with minor modifications in the electronics.Universidad Carlos III de MadridPublicad

Thermal unmanned aerial vehicles for the identification of microclimatic refugia in topographically complex areas

Biodiversity loss is one of the most relevant consequences of climate change. Therefore, identifying areas and environmental features that allow certain organisms to be less exposed to the effects of the current global warming is priority for biodiversity conservation. In this study, we describe a novel approach for the identification of microclimatic refugia in rugged mountain areas, specifically for the detection of most thermally stable areas, using an unmanned aerial vehicle (UAV) capable of recording in the visible and thermal infrared spectral bands. We estimated land surface temperatures (LST) at very-high spatial resolution in six topographically complex sectors of the Pyrenees (NE Spain), across seasons with vegetative activity (summer 2020, autumn 2020, spring 2021, and summer 2021), and at two thermally contrasted times of the day (early in the morning: LSTmin, and in the afternoon: LSTmax). LST were validated with a network of miniaturized temperature sensors in the field. LSTmin and LSTmax allowed us to calculate the daily thermal range of each sector across the seasons, and thus the most thermally stable areas over the year. To reveal the importance of different variables on low and narrow thermal ranges we applied Gradient Boosted Models to seven terrain variables derived from ALS-LiDAR (slope, northness, eastness, heat load, wind exposure index, SAGA's topographic wetness index, and vector ruggedness measure) and a proxy of forest density through the three-dimensional point clouds of the UAV data. The northness was the variable that most promoted thermal stability, followed by the slope and forest density, so that microclimatic refugia resulted to be located in northern slopes, small sites under rocky cliffs, and forested areas. Our results demonstrate that thermal UAVs can become promising tools for the identification of microclimatic refugia in topographically complex areas, providing information at unprecedented spatial resolution, and thus of high interest for biodiversity conservation

Patrones de actividad física en una muestra española

Este trabajo pretende describir la frecuencia y las actividades físicas y deportivas que realiza una muestra de hombres y mujeres de la provincia de Granada (lo que denominamos perfil de actividad física). Nos interesaba además, ver la frecuencia de práctica de actividades físicas y deportivas que cada uno de los sujetos de la muestra ha realizado a lo largo de su vida (niveles de actividad física). Para ello seleccionamos una muestra de 625 sujetos de ambos sexos, de diferentes niveles culturales y de práctica de actividades físicas y deportivas. Los resultados indican diferencias entre grupos en la práctica de actividades físicas y que los sujetos que en la actualidad realizan más actividad física son también los que más actividad física han realizado a lo largo de su vidaThis work attempted to describe the frequency and type of physical and sports activities in a sample of men and women in the province of Granada (which we call profile of physical activity). We were also interested in seeing the frequency of physical and sports activities for each of the subjects in our sample throughout the course of their lives (levels of physical activity). The sample consisted of 625 men and women of varying socio-cultural levels and different levels of physical and sports activities. The results show between group differences in the practice of physical activities and that those subjects who currently engage in higher levels of physical activity are those who engage in higher levels through the course of their live

Advanced multifunctional optical switch for nnultimode optical fiber networks

In this work, an advanced multifunctional optical switch based on multimode fibers is proposed. It can work as a 3×1 optical multiplexer/combiner, a 2×2 optical switch, a variable optical attenuator and a variable optical power splitter. All these functionalities can be developed in the same device without any hardware modification, only by using the proper ports and control electronics. The proposed switch has been developed for being used in the visible and near infrared wavelength range: 450–650 nm for optical fiber automobile applications, 650–850 nm for home broadband applications; and 850–1300 nm for multimode fiber access networks. Up to three different types of twisted nematic liquid crystal cells have been designed and fabricated for fulfilling these different wavelength ranges as part of the proposed device. The multifunctional switch has been implemented and experimentally tested. Crosstalk usually better than−15 dB at 532 nm, 660 nm and 850 nm, in any state has been measured. Switching is achieved at voltage levels of 4 Vrms. Fiber to fiber insertion losses when operating as a 2×2 optical switch, range from 10 to 15 dB within 200 nm wavelength range; with a non-optimized optics for collimation and coupling.This work was partially supported by CICYT (TEC2009-14718-C03-03-MCI), by the European Commission through the NoE BONE (Project no. 216863), and FACTOTEM-II-CM: S2009/ESP-1781 Projects.Publicad

Changes induced by glucose in the plasma membrane properties of pancreatic islets

Partially purified membranes obtained from rat pancreatic isolated islets preincubated for 3 min with 3.3 and 16.6 mM glucose were labelled with 1,6-diphenyl-1,3,5-hexatriene to study fluorescence polarization. Other islets, incubated for 5 min with the same glucose concentration, were extracted and phospholipids separated by thin-layer chromatography. The composition of phospholipids of fatty acids was then studied by gas-liquid chromatography. Arrhenius plots of the microviscosity in membranes obtained from islets exhibited two components, a steeper slope below 18 degrees C and a gentler slope above 18 degrees C, indicating greater flow activation energy at temperatures below the transition point. Exposure of islets to 16.6 mM glucose significantly increased the flow activation energy (delta E), below and above the transition point. Islets incubated for 5 min with 16.6 mM glucose showed an increase in the percentage composition of 12:0 and 18:2 together with a decrease in the 20:2 W6 and 22:3 W3 fatty acids esterified to phospholipids. Regardless of these changes, no significant alterations occurred in the proportion of saturated fatty acids or in the double bond index; these measurements therefore did not account for the effects of glucose concentration in flow activation energy. The thermotropic changes reported here might be the consequence of some degree of disorder induced by glucose upon the membrane structure. This order alteration could either favor the membrane fusion which occurs during the emiocytosis or only reflects the consequence of such a process.Facultad de Ciencias Médica