A New Insight on Phased Array Ultrasound Inspection in MIG/MAG Welding

Weldment inspection is a critical process in the metal industry. It is first conducted visually, then manually and finally using instrumental techniques such as ultrasound. We made one hundred metal inert/active gas (MIG/MAG) weldments on plates of naval steel S275JR+N with no defects, and inducing pores, slag intrusion and cracks. With the objective of the three-dimensional reconstruction of the welding defects, phased array ultrasound inspections were carried out. Error-free weldment probes were used to provide the noise level. The results can be summarized as follows. (i) The top view obtained from the phased array provided no conclusive information about the welding defects. The values of the echo amplitudes were about 70 mV for pores and cracks, and greater than 150 mV for slag intrusion, all of which showed great variability. (ii) The sectional data did not lie at the same depths and they needed to be interpolated. (iii) The interpolated sectional views, or C-scans, allowed the computation of top views at any depth, as well as the three-dimensional reconstruction of the defects. (iv) The use of the simplest tool, consisting of the frequency histogram and its statistical moments, was sufficient to classify the defects. The mean echo amplitudes were 33 mV for pores, 72.16 mV for slag intrusion and 43.19 mV for cracks, with standard deviations of 8.84 mV, 24.64 mV and 12.39 mV, respectively. These findings represent the first step in the automatic classification of welding defects.This research was funded by CEI.MAR Cadiz, 2020-PR003

Characterisation of the fabrication process of freestanding SU-8 microstructures integrated in printing circuit board in microelectromechanical systems

The characterisation of the fabrication process to develop freestanding SU-8 structures integrated in printing circuit board in microelectromechanical systems (PCBMEMS) technology is presented. SU-8 microcantilevers, microbridges, microchannels and micromembranes have been fabricated following the described procedure. Adherence between FR4 substrate and SU-8 has been examined using the destructive blister method, evaluating the surface energy. Residual thermal stress has also been analysed for this integration and compared when using other substrates. Moreover, an estimation of the copper wet etching with cupric chloride has been performed in order to understand how this isotropic etching affects the geometry of the copper structures. Finally, stiction has been observed and examined, estimating the adhesion energy responsible for this effect

Semi-Automatic Lab-on-PCB System for Agarose Gel Preparation and Electrophoresis for Biomedical Applications

In this paper, a prototype of a semi-automatic lab-on-PCB for agarose gel preparation and electrophoresis is developed. The dimensions of the device are 38x34 mm2 and it includes a conductivity sensor for detecting the TAE buffer (Tris-acetate-EDTA buffer), a microheater for increasing the solubility of the agarose, a negative temperature coefficient (NTC) thermistor for controlling the temperature, a light dependent resistor (LDR) sensor for measuring the transparency of the mixture, and two electrodes for performing the electrophoresis. The agarose preparation functions are governed by a microcontroller. The device requires a PMMA structure to define the wells of the agarose gel, and to release the electrodes from the agarose. The maximum voltage and current that the system requires are 40 V to perform the electrophoresis, and 1 A for activating the microheater. The chosen temperature for mixing is 80ºC, with a mixing time of 10 min. In addition, the curing time is about 30 min. This device is intended to be integrated as a part of a larger lab-on-PCB system for DNA amplification and detection. However, it can be used to migrate DNA amplified in conventional thermocyclers. Moreover, the device can be modified for preparing larger agarose gels and performing electrophoresis.Consejería de Economía y Conocimiento de Andalucía P18-RT-1745Unión Europea US-126598

De la fundación de asido

El hallazgo reciente de materiales arqueológicos de época tartésica en la periferia del actual casco urbano de Medina Sidonia, en la provincia de Cádiz, ha venido a confirmar la tradición historiográfica que remonta la fundación de la ciudad a los tiempos de la colonización fenicia. El presente trabajo da cuenta de dichos nuevos descubrimientos, y los somete a valoración. A la vez, intenta incardinarlos en el panorama de la gran expansión demográfica que conoció el mundo tartésico durante los siglos VIII y VII a.C.Archaeological materials from the tartesic period have been recently found in the surroundings of Medina Sidonia (province of Cádiz). This fact confirms the historiographic tradition of dating her foundation during the phoenician colonization. The birth of Medina Sidonia coincides with the demographic growth of the tartesian world that took place through the VIIIth. and VIIth. centuries b.C

Development of formal dynamic models with Microsoft Excel for greenhouse climate control.

Simple climate models performed with a widespread computer tool (Microsoft® Excel) could be useful for researchers or even greenhouse growers. A model of this type was used in three independent studies (heating, ventilation and cooling). The error in the calculation of temperature was lower than 2.5 ºC, and the error in the calculation of relative humidity was lower than 9%, in the validation of the model. The main advantage of the method of modelling is the possibility of fitting the coefficients with the tool SOLVER of Microsoft® Excel in each greenhouse, an easy method for both scientist and growers

Experimental results and modelling of humidity control strategies for greenhouses in continental and coastal settings in the Mediterranean region. I: Experimental results and model development

Experimental strategies for controlling humidity were compared in a greenhouse sited in Madrid, a continental site in the Mediterranean region. Small roof window apertures significantly reduced the relative humidity with only a limited increase in associated energy consumption. A simplified climate model with four energy exchange terms (heating, insolation, losses through structure, and losses through windows) and three mass exchange terms (evapotranspiration, losses through structure, and losses through windows) was validated, allowing relative humidity to be predicted with an error of < 9%

Apps como vehículo de aprendizaje en naturación urbana y campos deportivos

Los dispositivos electrónicos suponen una oportunidad para el proceso de enseñanza-aprendizaje en las aulas. El uso de apps (applications) o lo que es lo mismo, aplicaciones para dispositivos móviles tales como tablets o teléfonos móviles, es cada vez mayor en el ámbito privado, existiendo aplicaciones tan diversas como para el cálculo de distancias y velocidades recorridas, seguimiento de dietas nutricionales o contaje de la puntuación en numerosos deportes. Existen así mismo aplicaciones interesantes para poder ser usadas en la Universidad a través de las prácticas de las asignaturas orientadas hacia la ingeniería y en el entorno profesional. Algunos ejemplos podrían ser aplicaciones que permiten hacer trabajar a los dispositivos como si fueran acelerómetros, calculadores de superficies, o apps que permiten detectar enfermedades en plantas o necesidades de riego. Determinar el soporte electrónico más utilizado por los estudiantes en el aula permitirá conocer las posibilidades de incorporar estas aplicaciones en el ámbito universitario. Por otro lado, las redes sociales permiten generar un entorno para la difusión de conocimientos y debates interesantes en la Universidad. Sin embargo, no todas tienen las mismas posibilidades ni todas favorecen el entorno colaborativo que se busca en la docencia.Durante el curso 2018-2019 se está llevando a cabo un estudio, financiado por la Universidad Politécnica de Madrid (Redes sociales y uso de TICs como vehículo de aprendizaje en áreas verdes y naturación urbana) para conocer los dispositivos electrónicos de los que disponen los alumnos en el aula, así como las redes sociales más habituales entre ellos. Este estudio es continuación de otro realizado hace cinco años, con lo que es posible conocer la evolución que se ha producido en las aulas del área agroforestal y poder adaptar la docencia a la evolución tecnológica y social del momento

Experimental results and modelling of humidity control strategies for greenhouses in continental and coastal settings in the Mediterranean region. II: Modelling of strategies

Strategies for humidity control —with and without heating— were evaluated via simulations performed with a previously developed model (see accompanying paper, this issue, part I). With heating, the best strategy combined the use of a humidity setpoint with step control of the roof window, increasing the ventilation in line with the outside temperature. Without heating, the best strategy again combined the use of a humidity setpoint with step control of the roof window, but required ventilation to be increased in line with the inside air temperature

Experimental results and modelling of humidity control strategies from greenhouses in continental and coastal setting in the Mediterranean regíon. I : Experimental results and model development.

Experimental strategies for controlling humidity were compared in a greenhouse sited in Madrid, a continental site in the Mediterranean region. Small roof window apertures significantly reduced the relative humidity with only a limited increase in associated energy consumption. A simplified climate model with four energy exchange terms (heating, insolation, losses through structure, and losses through windows) and three mass exchange terms (evapotranspiration, losses through structure, and losses through windows) was validated, allowing relative humidity to be predicted with an error of < 9%. - Se ensayaron una serie de estrategias experimentales para el control de la humedad en un invernadero de Madrid, España. Se comprobó que pequeñas aperturas de la ventana cenital reducían significativamente el nivel de humedad con limitados incrementos del consumo de energía en calefacción. Se validó un modelo climático simplificado con cuatro términos de intercambio de energía (calefacción, radiación solar, pérdidas a través de la cubierta y pérdidas a través de las ventanas) y tres términos de intercambio de humedad (evapotranspiración, pérdidas a través de la cubierta y pérdidas a través de las ventanas), modelo que permitió predecir la humedad relativa con un error inferior al 9%

Wind pumps for irrigating greenhouse crops: Comparison in different socio-economical frameworks

A methodology is applied for economic evaluation of water pumping technologies. Different socioeconomic frameworks are considered for Spain, Cuba and Pakistan. The levelised cost of energy is used to determine the best technology. Wind speed, distance to grid, water storage size and elevation are considered. The water elevation has greater influence on wind pumps than on solar PV pumping