Dardo Guaraglia - Academia.edu (original) (raw)

Papers by Dardo Guaraglia

With the aim of obtaining correct field measurements some common sense rules have to be followed.... more With the aim of obtaining correct field measurements some common sense rules have to be followed. A set of suggestions will be offered below with the intention of preventing some common mistakes. Even when some of the ideas herein presented are known, having them collected in an ordered form could help in preparing field works. These rules are divided according to different phases in the data acquisition process, such as deciding the use of an instrument, installing it in the field, assuring data quality, etc. Instrument's users have to be familiar with the potentialities and limitations of their instrument before installing them in the field. For this reason, at the end of the chapter, a case study with instruments and sensors available in most laboratories is presented. It is intended to show why researchers should perform their own tests on instruments before using them.

Soil Science Society of America Journal, Jul 1, 2001

1984; Parton, 1984; Kemp et al., 1992). These models predict maximum, minimum, and daily mean soi... more 1984; Parton, 1984; Kemp et al., 1992). These models predict maximum, minimum, and daily mean soil tem-A model based on an electrical analogy between a soil column and peratures rather well. However, calculation of mean an electrical transmission line was developed to predict temperature values during normalizing or filtering processes results and heat flow as functions of depth and time in a sandy soil, taking into account changes in soil thermal conductivity and volumetric heat in loss of high frequency information. According to the capacity due to variations in water content. The model was excited Nyquist theorem (Schwartz and Shaw, 1975), at least alternatively by both measured soil temperature at the 1-cm depth two input samples per hour are needed to reproduce and solar radiation [S r (t)], and solved with available electrical analysis a bandlimited random hourly soil temperature. Thus, software. The results were compared with field data collected during models identified from input/output filtered data are a 35-d field experiment carried out in the Lido beach, Venice, Italy. not able to recover high frequency information because A very simple transfer function was identified for using measured this information was not taken into account in the sys-S r (t) as the input signal. This transfer function turned out to vary tem (model) identification process. It can be concluded inversely with S r (t). When the model is excited by temperature, and that these models are valid for predicting low frequency soil water content corrected every 5 d, the root mean square error soil temperature fluctuations, but they do not seem to (RMSE) for the calculated temperature at the 5-cm depth is less than 1؇C. When it is excited by S r (t), the RMSE at the 1-cm depth is less be the most adequate ones for predicting hourly temperthan 2؇C. Hourly temperatures at different depths were found to ature variations. Pikul (1991) and Katul and Parlange depend strongly on surface phenomena, and to a lesser extent on other (1993) use a surface energy balance approach for prefactors like soil water content below the top layers.

Modeling of coastal aquifers with scarce field data

El conjunto de datos se compone de varias carpetas dentro de un archivo zip. Se presentan los dat... more El conjunto de datos se compone de varias carpetas dentro de un archivo zip. Se presentan los datos utilizados para la elaboración de un modelo eléctrico con el uso de escasos datos aplicado a un acuífero costero.Facultad de Ingenierí

De Gruyter Open Poland, Oct 8, 2014

Offset and Gain Errors 18 2.2.6 Drift 20 2.2.7 An Example of Sensor Specifications 20 2.3 Spatial... more Offset and Gain Errors 18 2.2.6 Drift 20 2.2.7 An Example of Sensor Specifications 20 2.3 Spatial Characteristics of Sensors 22 2.3.1 The Decibel 22 2.3.2 Sensor Directivity 23 2.3.3 Spatial Averaging 26 2.4 Time and Frequency Characteristics of Sensors and Systems 27 2.4.1 Introduction 27 2.4.2 Frequency Content of Signals 28 2.4.3 Frequency Response 29 2.4.4 Bandwidth 31 2.4.5 Time Constant 34 2.4.6 Rise Time and Fall Time 36 2.4.7 Time Constant and Bandwidth Relation 36 2.4.8 Rise Time and Bandwidth Relation 38 2.4.9 Measuring the Rise Time of a Phenomenon by Means of an Instrument 38 2.4.10 Summary 38 2.4.11 Examples to Help Fix Previous Concepts 39 2.5 Filters 43 2.5.1 Noise Reduction by Filtering 44 2.5.2 Filter Delay 46 2.5.3 Spatial Filtering 46 2.6 Summary 47 References 48 3

The sedimentary Salado basin is located in the Province of Buenos Aires, Argentina, and extends f... more The sedimentary Salado basin is located in the Province of Buenos Aires, Argentina, and extends for about 150,000 km 2 ; of which 50,000 km 2 correspond to the lower estuary (or marine estuary) of the Rio de la Plata and to the adjacent sector of the Atlantic Ocean. The basin, which takes its name from the homonymous river that crosses it, is composed of blocks that allowed fluvial-lacunar environments with extended flood plains to be developed. The present configuration of the basin comes from recent sedimentary fill, and shows a broad accretion plain with a low topographic slope that extends with similar features toward the continental shelf. With a sedimentary thickness of over 6,000 m, the Salado basin is characterized by a large vertical development of Upper Paleozoic, Mesozoic and Tertiary continental sediments, with no outcrops from before the Quaternary. The origin of the basin can be related to the development of extensional fractures that took place over ancient weakness zones where the starting aperture mechanism of Gondwana began. The geographical location of the basin, together with its large extent, low elevation over sea level, geology, geomorphology and the prevalent humid climate have produced a particular hydrological behavior with strong ecological characteristics. Vertical water movements (evapotranspiration-infiltration) predominate over horizontal ones (runoff), and there is a strong connection between surface water and

A traditional approach to introduce remote sensing systems is to group them into two categories, ... more A traditional approach to introduce remote sensing systems is to group them into two categories, namely passive and active systems. In passive remote sensing the equipment used to acquire the information from the target (object under study) gathers the data from the natural energy emitted and/or reflected by the target. The measuring system described in Sections (4.7.6) and (4.7.7) can be considered a kind of passive remote system. In active remote sensing, instead, the measuring system emits energy that "illuminates" the target, and receives part of its own energy reflected or scattered by the target (Lillesand et al., 2004). In both cases the energy arriving from the target is analyzed to draw information about the characteristics of the target (velocity, position, size, temperature, aerosol, etc.). Remote sensing can be performed in different media: solid, fluid or vacuum. Acoustic systems used for measuring flow, as those presented in Section (5.4.4.), could be considered remote sensing systems in a fluid (water) where the sensing wave is a sound wave. Other systems use electromagnetic waves in air, as in the case of radar, or in a physical solid medium such as in fiber optic or soil; an example of the last method is called Distributed Temperature Sensing (DTS) and will be described below. In this chapter we will pay attention to active remote sensing systems, where energy is irradiated from the measuring systems to the target, the propagating wave being either electromagnetic or acoustic.

Nova Science Publishers, 2017

Laboratorio de Entrenamiento Multidisciplinario para la Investigación Tecnológica (LEMIT), 1975

La medición de niveles de aguas subterráneas representa un procedimiento frecuente en hidrogeolog... more La medición de niveles de aguas subterráneas representa un procedimiento frecuente en hidrogeología. En este trabajo se intenta concientizar acerca de los recaudos que se deberían tener, antes, durante y con posterioridad a la utilización de registradores de niveles con sensores de presión. Se han realizado experiencias bajo distintas condiciones y se han examinado sus resultados. Se utilizan en forma comparativa los datos obtenidos con 5 registradores de presión sometidos a similares variaciones. Se analizan las características de estos registradores y se identifican posibles fuentes de error. Teniendo en cuenta las condiciones de campo en las que se realizan estas mediciones, se describe la influencia de la presión atmosférica en la calidad de los datos, los efectos de los cambios de la temperatura, la estabilidad de la calibración y la recalibración. Se resalta la necesidad de verificación del comportamiento del instrumento, en relación a la aplicación a realizar, y la estimación cuantitativa del error en las mediciones. Palabras clave: aguas subterráneas, registradores de nivel, sensores de presión, calibración, errores.

Those beginning to read the book at this chapter could find it troublesome with so many reference... more Those beginning to read the book at this chapter could find it troublesome with so many references to previous chapters, but it is the only way we found to make this chapter both short and straightforward. We think that these references will also help the readers to refresh the needed concepts that they might have forgotten since they read the first chapters. We will focus this chapter on the technical characteristics of the instruments on-board satellites, avoiding any reference to the way in which the geometric aspects of the flight determine the composition of the images. Nor are we going to treat how images have to be interpreted. These subjects can be found in most books on remote sensing (Campbell, 2007; Lillesand et al., 2004). As in the rest of the book our interest will be centered on how instruments work in order to understand their applications and limitations. 10.2 Preliminary Discussion Satellite-based remote sensing is a vast and rapidly changing field. Battery degradation, unexpected failures and exhaustion of propellants, among others, are problems that make satellites' life quite limited. For example, geosynchronous satellites require propellants to keep them in orbit and to maintain their altitude so that the solar panels and antenna can be pointed adequately. Therefore, because they run out of propellant, the useful lifetime of geosynchronous satellites averages about fifteen years (Kurtin, 2013). Also, some missions with polar orbits planned for several years and carrying sophisticated remote sensing equipment lasted less than two years due to failures in the energy system or in the instruments (http://coaps.fsu. edu/scatterometry/about/overview.php). Similar problems are faced by communication satellites (Section (9.6.4.1)). The short operating life of satellites, along with the rapid changes in electronics and satellite technologies, makes remote sensing from space a very dynamic field. There are many different instruments working on board spacecrafts, as well as many names, e.g. active microwave instruments, synthetic aperture radar, wind scatterometer, radar altimeter, scanning radiometer, ozone monitor, microwave sounder, precise range and range rate equipment, laser reflector, microwave radiometer, LIDAR, precise orbit Doppler locator, laser tracker, GPS tracker, precipitation radar, microwave imager, visible infrared scanner, clouds and Earth's radiant energy system, lighting imaging sensor, etc.

In recent decades, advances in physics and electronics have enabled the development of devices th... more In recent decades, advances in physics and electronics have enabled the development of devices that take information from a physical or chemical phenomenon and create or modify an electrical signal upon which this information is "copied". These devices are known by different names in instrumentation literature making unavoidable an introduction to some terminology frequently used. In the electronic instrumentation literature some authors use the words transducer, sensor, actuator and detector in a way that could confuse the reader. This practice is often correct, because a device could meet more than one definition, but this is not always the case. Formal definitions from dictionaries provide some guidelines about how to use these words. The Webster's on-line dictionary (http://www.merriam-webster.com/dictionary) defines transducer as: "A device that is actuated by power from one system and supplies power usually in another form to a second system (a loudspeaker is a transducer that transforms electrical signals into sound energy)" The same on-line dictionary defines sensor as: "A device that responds to a physical stimulus (as heat, light, sound, pressure, magnetism, or a particular motion) and transmits a resulting impulse (as for measurement or operating a control)" Dictionary definitions associate transducer with a device that converts one form of energy (or power) into another, and sensor with a device that perceives a physical stimulus giving a signal as a result. For example, microphones and hydrophones convert vibration into electricity, and thermocouples transform temperature into electricity, therefore they are examples of transducers (Fig. 2.1a). Pressure sensors, resistance temperature sensors, thermistors, strain gauges and photoresistors are examples of sensors, because they are supplied with electrical energy and give an electrical signal when subjected to a stimulus (Fig. 2.1b). Other authors (http://digital.ni.com) prefer to call active transducers those that generate an electric current or voltage in response to environmental stimulation, and passive transducers those that produce a change in some passive electrical quantity, such as capacitance, resistance, or inductance as a result of stimulation. Generally, the word actuator refers to a device that converts an electrical signal into a mechanical motion. For example, an electric motor fits this definition because when powered by voltage produces a mechanical rotation of an axis. Also, the automatic locking of the car's doors is made by an actuator.

Introduction to Modern Instrumentation For Hydraulics and Environmental Sciences

En la Provincia de Buenos Aires, Argentina, existen muchas instalaciones con lazos inductivos par... more En la Provincia de Buenos Aires, Argentina, existen muchas instalaciones con lazos inductivos para contar transito. La experiencia indica que las instalaciones son muy confiables y que podrian ser facilmente modificadas para ser utilizadas con clasificadores. A partir de la necesidad de contar con clasificadores de transito de bajo costo de instalacion y mantenimiento, bajo indice de vandalismo y larga vida util, se decidio desarrollar un clasificador utilizando lazos inductivos como sensores. En este trabajo se presentan los pasos del desarrollo y los resultados obtenidos con el equipo instalado en una ruta. Para este proyecto se evaluaron las firmas magneticas que el parque automotor genera sobre los lazos actualmente utilizados. Esto permitio desarrollar un equipo que utiliza la estimacion de la distancia del vehiculo al pavimento como variable de clasificacion. Esta innovacion permite la clasificacion confiable de cuatro categorias: autos y "pickups"; Camiones; Omnibus...

This subject is so vast that any attempt to address it within the limits of an introductory book ... more This subject is so vast that any attempt to address it within the limits of an introductory book has great chances to fail. A way to increase our chances of success is to reduce the subject to a few topics strictly linked to the instrumentation used in environmental sciences, and to the description of some examples of applications. In order to better understand this subject it is recommended that the reader be familiar with the way analog signals are converted into digital ones (Section (3.6)). All measuring systems produce data as a result, and these data must be evaluated sooner or later, either by an automatic system or a human being; "the final aim of a measurement process is taking a decision" (Ferrero, 2005). The immediacy with which the information should be assessed depends on the purpose for which it was collected. This purpose defines what to do with the information in the steps following the measurement: basically the information generated by an instrument can be stored, transmitted or both. The storage of information is treated at the end of the chapter, the transmission of data being the backbone of this chapter. It begins with a general introduction and goes on with generic issues on digital data with the purpose of establishing some concepts and the vocabulary frequently used. This generic approach to data communication concepts would hopefully help the reader to understand the transmission methods used at present in scientific instruments. Some characteristics of the transmissions systems, such as transmission delay, local and remote transmissions, network topologies, etc. are described. A concise mention of analog transmission is done followed by digital data transmission which, due to its importance, is the matter developed most extensively. Several digital transmission concepts, such as signal encoding, transmission modes, serial and parallel transmission, asynchronous and synchronous transmission, error detection and correction, etc., are developed with the aim of providing the minimum needed information to understand how instruments can transmit data. Finally, some effort is devoted to describe the three most commonly used media to transmit data from a field instrument (or group of instruments) to a central station, namely, private networks, digital telephony and satellite communications. It has to be stressed that in order to keep the explanations as simple as possible, the descriptions found in this chapter are basic. We do not delve into the details that some communications systems employ to transport data more safely. At present, complex communications systems employ very refined strategies and algorithms to protect the data and correct errors. These approaches, which increase transmitted data immunity and integrity, are merely delineated.

En este trabajo se presenta uno de los ultimos desarrollos transferidos desde la UID Gitec. El mi... more En este trabajo se presenta uno de los ultimos desarrollos transferidos desde la UID Gitec. El mismo consiste en el desarrollo de un equipo para evaluar la capacidad auditiva basado en emisiones otoacusticas (OAE). Estos equipos permiten evaluar la capacidad auditiva de un sujeto en forma objetiva, es decir, sin requerir respuestas por parte del paciente. Estas tecnicas permiten detectar problemas de audicion en pocos minutos con solo introducir una sonda en el canal auditivo. La utilizacion de OAE es relativamente reciente y su campo de aplicacion se concentra principalmente en neonatos para la deteccion temprana de hipoacusias. En nuestro pais, a partir de la promulgacion en el ano 2001 de la ley 25415 del Programa Nacional de deteccion de Hipoacusia se ha incluido dentro del plan de estudios a realizar a los recien nacidos. El presente desarrollo surgio a requerimiento de una empresa del ambito local que desarrolla y produce tecnologia medica para audiologia desde hace mas de 30 ...

With the aim of obtaining correct field measurements some common sense rules have to be followed.... more With the aim of obtaining correct field measurements some common sense rules have to be followed. A set of suggestions will be offered below with the intention of preventing some common mistakes. Even when some of the ideas herein presented are known, having them collected in an ordered form could help in preparing field works. These rules are divided according to different phases in the data acquisition process, such as deciding the use of an instrument, installing it in the field, assuring data quality, etc. Instrument's users have to be familiar with the potentialities and limitations of their instrument before installing them in the field. For this reason, at the end of the chapter, a case study with instruments and sensors available in most laboratories is presented. It is intended to show why researchers should perform their own tests on instruments before using them.

Soil Science Society of America Journal, Jul 1, 2001

1984; Parton, 1984; Kemp et al., 1992). These models predict maximum, minimum, and daily mean soi... more 1984; Parton, 1984; Kemp et al., 1992). These models predict maximum, minimum, and daily mean soil tem-A model based on an electrical analogy between a soil column and peratures rather well. However, calculation of mean an electrical transmission line was developed to predict temperature values during normalizing or filtering processes results and heat flow as functions of depth and time in a sandy soil, taking into account changes in soil thermal conductivity and volumetric heat in loss of high frequency information. According to the capacity due to variations in water content. The model was excited Nyquist theorem (Schwartz and Shaw, 1975), at least alternatively by both measured soil temperature at the 1-cm depth two input samples per hour are needed to reproduce and solar radiation [S r (t)], and solved with available electrical analysis a bandlimited random hourly soil temperature. Thus, software. The results were compared with field data collected during models identified from input/output filtered data are a 35-d field experiment carried out in the Lido beach, Venice, Italy. not able to recover high frequency information because A very simple transfer function was identified for using measured this information was not taken into account in the sys-S r (t) as the input signal. This transfer function turned out to vary tem (model) identification process. It can be concluded inversely with S r (t). When the model is excited by temperature, and that these models are valid for predicting low frequency soil water content corrected every 5 d, the root mean square error soil temperature fluctuations, but they do not seem to (RMSE) for the calculated temperature at the 5-cm depth is less than 1؇C. When it is excited by S r (t), the RMSE at the 1-cm depth is less be the most adequate ones for predicting hourly temperthan 2؇C. Hourly temperatures at different depths were found to ature variations. Pikul (1991) and Katul and Parlange depend strongly on surface phenomena, and to a lesser extent on other (1993) use a surface energy balance approach for prefactors like soil water content below the top layers.

Modeling of coastal aquifers with scarce field data

El conjunto de datos se compone de varias carpetas dentro de un archivo zip. Se presentan los dat... more El conjunto de datos se compone de varias carpetas dentro de un archivo zip. Se presentan los datos utilizados para la elaboración de un modelo eléctrico con el uso de escasos datos aplicado a un acuífero costero.Facultad de Ingenierí

De Gruyter Open Poland, Oct 8, 2014

Offset and Gain Errors 18 2.2.6 Drift 20 2.2.7 An Example of Sensor Specifications 20 2.3 Spatial... more Offset and Gain Errors 18 2.2.6 Drift 20 2.2.7 An Example of Sensor Specifications 20 2.3 Spatial Characteristics of Sensors 22 2.3.1 The Decibel 22 2.3.2 Sensor Directivity 23 2.3.3 Spatial Averaging 26 2.4 Time and Frequency Characteristics of Sensors and Systems 27 2.4.1 Introduction 27 2.4.2 Frequency Content of Signals 28 2.4.3 Frequency Response 29 2.4.4 Bandwidth 31 2.4.5 Time Constant 34 2.4.6 Rise Time and Fall Time 36 2.4.7 Time Constant and Bandwidth Relation 36 2.4.8 Rise Time and Bandwidth Relation 38 2.4.9 Measuring the Rise Time of a Phenomenon by Means of an Instrument 38 2.4.10 Summary 38 2.4.11 Examples to Help Fix Previous Concepts 39 2.5 Filters 43 2.5.1 Noise Reduction by Filtering 44 2.5.2 Filter Delay 46 2.5.3 Spatial Filtering 46 2.6 Summary 47 References 48 3

The sedimentary Salado basin is located in the Province of Buenos Aires, Argentina, and extends f... more The sedimentary Salado basin is located in the Province of Buenos Aires, Argentina, and extends for about 150,000 km 2 ; of which 50,000 km 2 correspond to the lower estuary (or marine estuary) of the Rio de la Plata and to the adjacent sector of the Atlantic Ocean. The basin, which takes its name from the homonymous river that crosses it, is composed of blocks that allowed fluvial-lacunar environments with extended flood plains to be developed. The present configuration of the basin comes from recent sedimentary fill, and shows a broad accretion plain with a low topographic slope that extends with similar features toward the continental shelf. With a sedimentary thickness of over 6,000 m, the Salado basin is characterized by a large vertical development of Upper Paleozoic, Mesozoic and Tertiary continental sediments, with no outcrops from before the Quaternary. The origin of the basin can be related to the development of extensional fractures that took place over ancient weakness zones where the starting aperture mechanism of Gondwana began. The geographical location of the basin, together with its large extent, low elevation over sea level, geology, geomorphology and the prevalent humid climate have produced a particular hydrological behavior with strong ecological characteristics. Vertical water movements (evapotranspiration-infiltration) predominate over horizontal ones (runoff), and there is a strong connection between surface water and

A traditional approach to introduce remote sensing systems is to group them into two categories, ... more A traditional approach to introduce remote sensing systems is to group them into two categories, namely passive and active systems. In passive remote sensing the equipment used to acquire the information from the target (object under study) gathers the data from the natural energy emitted and/or reflected by the target. The measuring system described in Sections (4.7.6) and (4.7.7) can be considered a kind of passive remote system. In active remote sensing, instead, the measuring system emits energy that "illuminates" the target, and receives part of its own energy reflected or scattered by the target (Lillesand et al., 2004). In both cases the energy arriving from the target is analyzed to draw information about the characteristics of the target (velocity, position, size, temperature, aerosol, etc.). Remote sensing can be performed in different media: solid, fluid or vacuum. Acoustic systems used for measuring flow, as those presented in Section (5.4.4.), could be considered remote sensing systems in a fluid (water) where the sensing wave is a sound wave. Other systems use electromagnetic waves in air, as in the case of radar, or in a physical solid medium such as in fiber optic or soil; an example of the last method is called Distributed Temperature Sensing (DTS) and will be described below. In this chapter we will pay attention to active remote sensing systems, where energy is irradiated from the measuring systems to the target, the propagating wave being either electromagnetic or acoustic.

Nova Science Publishers, 2017

Laboratorio de Entrenamiento Multidisciplinario para la Investigación Tecnológica (LEMIT), 1975

La medición de niveles de aguas subterráneas representa un procedimiento frecuente en hidrogeolog... more La medición de niveles de aguas subterráneas representa un procedimiento frecuente en hidrogeología. En este trabajo se intenta concientizar acerca de los recaudos que se deberían tener, antes, durante y con posterioridad a la utilización de registradores de niveles con sensores de presión. Se han realizado experiencias bajo distintas condiciones y se han examinado sus resultados. Se utilizan en forma comparativa los datos obtenidos con 5 registradores de presión sometidos a similares variaciones. Se analizan las características de estos registradores y se identifican posibles fuentes de error. Teniendo en cuenta las condiciones de campo en las que se realizan estas mediciones, se describe la influencia de la presión atmosférica en la calidad de los datos, los efectos de los cambios de la temperatura, la estabilidad de la calibración y la recalibración. Se resalta la necesidad de verificación del comportamiento del instrumento, en relación a la aplicación a realizar, y la estimación cuantitativa del error en las mediciones. Palabras clave: aguas subterráneas, registradores de nivel, sensores de presión, calibración, errores.

Those beginning to read the book at this chapter could find it troublesome with so many reference... more Those beginning to read the book at this chapter could find it troublesome with so many references to previous chapters, but it is the only way we found to make this chapter both short and straightforward. We think that these references will also help the readers to refresh the needed concepts that they might have forgotten since they read the first chapters. We will focus this chapter on the technical characteristics of the instruments on-board satellites, avoiding any reference to the way in which the geometric aspects of the flight determine the composition of the images. Nor are we going to treat how images have to be interpreted. These subjects can be found in most books on remote sensing (Campbell, 2007; Lillesand et al., 2004). As in the rest of the book our interest will be centered on how instruments work in order to understand their applications and limitations. 10.2 Preliminary Discussion Satellite-based remote sensing is a vast and rapidly changing field. Battery degradation, unexpected failures and exhaustion of propellants, among others, are problems that make satellites' life quite limited. For example, geosynchronous satellites require propellants to keep them in orbit and to maintain their altitude so that the solar panels and antenna can be pointed adequately. Therefore, because they run out of propellant, the useful lifetime of geosynchronous satellites averages about fifteen years (Kurtin, 2013). Also, some missions with polar orbits planned for several years and carrying sophisticated remote sensing equipment lasted less than two years due to failures in the energy system or in the instruments (http://coaps.fsu. edu/scatterometry/about/overview.php). Similar problems are faced by communication satellites (Section (9.6.4.1)). The short operating life of satellites, along with the rapid changes in electronics and satellite technologies, makes remote sensing from space a very dynamic field. There are many different instruments working on board spacecrafts, as well as many names, e.g. active microwave instruments, synthetic aperture radar, wind scatterometer, radar altimeter, scanning radiometer, ozone monitor, microwave sounder, precise range and range rate equipment, laser reflector, microwave radiometer, LIDAR, precise orbit Doppler locator, laser tracker, GPS tracker, precipitation radar, microwave imager, visible infrared scanner, clouds and Earth's radiant energy system, lighting imaging sensor, etc.

In recent decades, advances in physics and electronics have enabled the development of devices th... more In recent decades, advances in physics and electronics have enabled the development of devices that take information from a physical or chemical phenomenon and create or modify an electrical signal upon which this information is "copied". These devices are known by different names in instrumentation literature making unavoidable an introduction to some terminology frequently used. In the electronic instrumentation literature some authors use the words transducer, sensor, actuator and detector in a way that could confuse the reader. This practice is often correct, because a device could meet more than one definition, but this is not always the case. Formal definitions from dictionaries provide some guidelines about how to use these words. The Webster's on-line dictionary (http://www.merriam-webster.com/dictionary) defines transducer as: "A device that is actuated by power from one system and supplies power usually in another form to a second system (a loudspeaker is a transducer that transforms electrical signals into sound energy)" The same on-line dictionary defines sensor as: "A device that responds to a physical stimulus (as heat, light, sound, pressure, magnetism, or a particular motion) and transmits a resulting impulse (as for measurement or operating a control)" Dictionary definitions associate transducer with a device that converts one form of energy (or power) into another, and sensor with a device that perceives a physical stimulus giving a signal as a result. For example, microphones and hydrophones convert vibration into electricity, and thermocouples transform temperature into electricity, therefore they are examples of transducers (Fig. 2.1a). Pressure sensors, resistance temperature sensors, thermistors, strain gauges and photoresistors are examples of sensors, because they are supplied with electrical energy and give an electrical signal when subjected to a stimulus (Fig. 2.1b). Other authors (http://digital.ni.com) prefer to call active transducers those that generate an electric current or voltage in response to environmental stimulation, and passive transducers those that produce a change in some passive electrical quantity, such as capacitance, resistance, or inductance as a result of stimulation. Generally, the word actuator refers to a device that converts an electrical signal into a mechanical motion. For example, an electric motor fits this definition because when powered by voltage produces a mechanical rotation of an axis. Also, the automatic locking of the car's doors is made by an actuator.

Introduction to Modern Instrumentation For Hydraulics and Environmental Sciences

En la Provincia de Buenos Aires, Argentina, existen muchas instalaciones con lazos inductivos par... more En la Provincia de Buenos Aires, Argentina, existen muchas instalaciones con lazos inductivos para contar transito. La experiencia indica que las instalaciones son muy confiables y que podrian ser facilmente modificadas para ser utilizadas con clasificadores. A partir de la necesidad de contar con clasificadores de transito de bajo costo de instalacion y mantenimiento, bajo indice de vandalismo y larga vida util, se decidio desarrollar un clasificador utilizando lazos inductivos como sensores. En este trabajo se presentan los pasos del desarrollo y los resultados obtenidos con el equipo instalado en una ruta. Para este proyecto se evaluaron las firmas magneticas que el parque automotor genera sobre los lazos actualmente utilizados. Esto permitio desarrollar un equipo que utiliza la estimacion de la distancia del vehiculo al pavimento como variable de clasificacion. Esta innovacion permite la clasificacion confiable de cuatro categorias: autos y "pickups"; Camiones; Omnibus...

This subject is so vast that any attempt to address it within the limits of an introductory book ... more This subject is so vast that any attempt to address it within the limits of an introductory book has great chances to fail. A way to increase our chances of success is to reduce the subject to a few topics strictly linked to the instrumentation used in environmental sciences, and to the description of some examples of applications. In order to better understand this subject it is recommended that the reader be familiar with the way analog signals are converted into digital ones (Section (3.6)). All measuring systems produce data as a result, and these data must be evaluated sooner or later, either by an automatic system or a human being; "the final aim of a measurement process is taking a decision" (Ferrero, 2005). The immediacy with which the information should be assessed depends on the purpose for which it was collected. This purpose defines what to do with the information in the steps following the measurement: basically the information generated by an instrument can be stored, transmitted or both. The storage of information is treated at the end of the chapter, the transmission of data being the backbone of this chapter. It begins with a general introduction and goes on with generic issues on digital data with the purpose of establishing some concepts and the vocabulary frequently used. This generic approach to data communication concepts would hopefully help the reader to understand the transmission methods used at present in scientific instruments. Some characteristics of the transmissions systems, such as transmission delay, local and remote transmissions, network topologies, etc. are described. A concise mention of analog transmission is done followed by digital data transmission which, due to its importance, is the matter developed most extensively. Several digital transmission concepts, such as signal encoding, transmission modes, serial and parallel transmission, asynchronous and synchronous transmission, error detection and correction, etc., are developed with the aim of providing the minimum needed information to understand how instruments can transmit data. Finally, some effort is devoted to describe the three most commonly used media to transmit data from a field instrument (or group of instruments) to a central station, namely, private networks, digital telephony and satellite communications. It has to be stressed that in order to keep the explanations as simple as possible, the descriptions found in this chapter are basic. We do not delve into the details that some communications systems employ to transport data more safely. At present, complex communications systems employ very refined strategies and algorithms to protect the data and correct errors. These approaches, which increase transmitted data immunity and integrity, are merely delineated.

En este trabajo se presenta uno de los ultimos desarrollos transferidos desde la UID Gitec. El mi... more En este trabajo se presenta uno de los ultimos desarrollos transferidos desde la UID Gitec. El mismo consiste en el desarrollo de un equipo para evaluar la capacidad auditiva basado en emisiones otoacusticas (OAE). Estos equipos permiten evaluar la capacidad auditiva de un sujeto en forma objetiva, es decir, sin requerir respuestas por parte del paciente. Estas tecnicas permiten detectar problemas de audicion en pocos minutos con solo introducir una sonda en el canal auditivo. La utilizacion de OAE es relativamente reciente y su campo de aplicacion se concentra principalmente en neonatos para la deteccion temprana de hipoacusias. En nuestro pais, a partir de la promulgacion en el ano 2001 de la ley 25415 del Programa Nacional de deteccion de Hipoacusia se ha incluido dentro del plan de estudios a realizar a los recien nacidos. El presente desarrollo surgio a requerimiento de una empresa del ambito local que desarrolla y produce tecnologia medica para audiologia desde hace mas de 30 ...