Some advances in extensive bridge monitoring using low cost dynamic characterization

Dynamic measurements will become a standard for bridge monitoring in the near future. This fact will produce an important cost reduction for maintenance. US Administration has a long term intensive research program in order to diminish the estimated current maintenance cost of US$7 billion per year over 20 years. An optimal intervention maintenance program demands a historical dynamical record, as well as an updated mathematical model of the structure to be monitored. In case that a model of the structure is not actually available it is possible to produce it, however this possibility does not exist for missing measurement records from the past. Current acquisition systems to monitor structures can be made more efficient by introducing the following improvements, under development in the Spanish research Project “Low cost bridge health monitoring by ambient vibration tests using wireless sensors”: (a) a complete wireless system to acquire sensor data, (b) a wireless system that permits the localization and the hardware identification of the whole sensor system. The applied localization system has been object of a recent patent, and (c) automatization of the modal identification process, aimed to diminish human intervention. This system is assembled with cheap components and allows the simultaneous use of a large number of sensors at a low placement cost. The engineer’s intervention is limited to the selection of sensor positions, probably based on a preliminary FE analysis. In case of multiple setups, also the position of a number of fixed reference sensors has to be decided. The wireless localization system will obtain the exact coordinates of all these sensors positions. When the selection of optimal positions is difficult, for example because of the lack of a proper FE model, this can be compensated by using a higher number of measuring (also reference) points. The described low cost acquisition system allows the responsible bridge administration to obtain historical dynamic identification records at reasonable costs that will be used in future maintenance programs. Therefore, due to the importance of the baseline monitoring record of a new bridge, a monitoring test just after its construction should be highly recommended, if not compulsory.

A low-cost alternative scheme to detect a 100 Gbps PM-DQPSK signal

We propose and demonstrate a low-cost alternative scheme of direct-detection to detect a 100Gbps polarization-multiplexed differential quadrature phase-shift keying (PM-DQPSK) signal. The proposed scheme is based on a delay line and a polarization rotator; the phase-shift keying signal is first converted into a polarization shift keying signal. Then, this signal is converted into an intensity modulated signal by a polarization beam splitter. Finally, the intensity-modulated signal is detected by balanced photodetectors. In order to demonstrate that our proposed receiver is suitable for using as a PM-DQPSK demodulator, a set of simulations have been performed. In addition to testing the sensitivity, the performance under various impairments, including narrow optical filtering, polarization mode dispersion, chromatic dispersion and polarization sensitivity, is analyzed. The simulation results show that our performance receiver is as good as a conventional receiver based on four delay interferometers. Moreover, in comparison with the typical receiver, fewer components are used in our receiver. Hence, implementation is easier, and total cost is reduced. In addition, our receiver can be easily improved to a bit-rate tunable receiver.

Integration of low-cost supervisory mobile robots in domestic wireless sensor networks

This paper presents a communication interface between supervisory low-cost mobile robots and domestic Wireless Sensor Network (WSN) based on the Zig Bee protocol from different manufacturers. The communication interface allows control and communication with other network devices using the same protocol. The robot can receive information from sensor devices (temperature, humidity, luminosity) and send commands to actuator devices (lights, shutters, thermostats) from different manufacturers. The architecture of the system, the interfaces and devices needed to establish the communication are described in the paper.

Low-cost manufacturing by fused filament fabrication of microwave waveguide passive devices for space applications

Presentación en poster de impresión 3D de guias de onda.

Low-Cost Radar-Based Target Identification Prototype using an Expert System

Smart and green cities are hot topics in current research because people are becoming more conscious about their impact on the environment and the sustainability of their cities as the population increases. Many researchers are searching for mechanisms that can reduce power consumption and pollution in the city environment. This paper addresses the issue of public lighting and how it can be improved in order to achieve a more energy efficient city. This work is focused on making the process of turning the streetlights on and off more intelligent so that they consume less power and cause less light pollution. The proposed solution is comprised of a radar device and an expert system implemented on a low-cost platform based on a DSP. By analyzing the radar echo in both the frequency and time domains, the system is able to detect and identify objects moving in front of it. This information is used to decide whether or not the streetlight should be turned on. Experimental results show that the proposed system can provide hit rates over 80%, promising a good performance. In addition, the proposed solution could be useful in kind of other applications such as intelligent security and surveillance systems and home automation.

Application of low cost technology for the management of irrigation in organic orchards

Throughout history, humans have cyclically return to their old traditions such as the organic orchards. Nowadays, these have been integrated into the modern cities and could supply fresh vegetables to the daily food improving human health. Organic orchards grow crops without pesticides and artificial fertilizers thus, they are respectful with the environment and guarantee the food's safety . In modern society, the application of new technology is a must, in this case to obtain an efficient irrigation. In order to monitor a proper irrigation and save water and energy, soil water content probes are used to measure soil water content. Among them, capacitive probes ,monitored with a specific data logger, are typically used. Most of them, specially the data loggers, are expensive and in many cases are not used. In this work, we have applied the open hardware Arduino to build and program a low cost datalogger for the programming of irrigation in an experimental organic orchard. Results showed that the application of such as low cost technology, which is easily available in the market and easy to understand, everyone can built and program its own device helping in managing water resources in organic orchards .

Detection of Biological CO2 and 1,3-Pentadiene Using Non-refrigerated Low-Cost MWIR Detectors

The early detection of spoiling metabolic products in contaminated food is a very important tool to control quality. Some volatile compounds produce unpleasant odours at very low concentrations, making their early detection very challenging. This is the case of 1,3-pentadiene produced by microorganisms through decarboxylation of the preservative sorbate. In this work, we have developed a methodology to use the data produced by a low-cost, compact MWIR (Mid-Wave IR) spectrometry device without moving parts, which is based on a linear array of 128 elements of VPD PbSe coupled to a linear variable filter (LVF) working in the spectral range between 3 and 4.6 ?m. This device is able to analyze food headspace gases through dedicated sample presentation setup. This methodology enables the detection of CO2 and the volatile compound 1,3-pentadiene, as compared to synthetic patrons. Data analysis is based on an automated multidimensional dynamic processing of the MWIR spectra. Principal component and discriminant analysis allow segregating between four yeast strains including producers and no producers. The segregation power is accounted as a measure of the discrimination quality.

Low cost 3D global instability analysis and flow sensitivity based on dynamic mode decomposition and high-order numerical tools

We explore the recently developed snapshot-based dynamic mode decomposition (DMD) technique, a matrix-free Arnoldi type method, to predict 3D linear global flow instabilities. We apply the DMD technique to flows confined in an L-shaped cavity and compare the resulting modes to their counterparts issued from classic, matrix forming, linear instability analysis (i.e. BiGlobal approach) and direct numerical simulations. Results show that the DMD technique, which uses snapshots generated by a 3D non-linear incompressible discontinuous Galerkin Navier?Stokes solver, provides very similar results to classical linear instability analysis techniques. In addition, we compare DMD results issued from non-linear and linearised Navier?Stokes solvers, showing that linearisation is not necessary (i.e. base flow not required) to obtain linear modes, as long as the analysis is restricted to the exponential growth regime, that is, flow regime governed by the linearised Navier?Stokes equations, and showing the potential of this type of analysis based on snapshots to general purpose CFD codes, without need of modifications. Finally, this work shows that the DMD technique can provide three-dimensional direct and adjoint modes through snapshots provided by the linearised and adjoint linearised Navier?Stokes equations advanced in time. Subsequently, these modes are used to provide structural sensitivity maps and sensitivity to base flow modification information for 3D flows and complex geometries, at an affordable computational cost. The information provided by the sensitivity study is used to modify the L-shaped geometry and control the most unstable 3D mode.

Cost and energy efficient reconfigurable embedded platform using Spartan-6 FPGAs

Modern FPGAs with run-time reconfiguration allow the implementation of complex systems offering both the flexibility of software-based solutions combined with the performance of hardware. This combination of characteristics, together with the development of new specific methodologies, make feasible to reach new points of the system design space, and make embedded systems built on these platforms acquire more and more importance. However, the practical exploitation of this technique in fields that traditionally have relied on resource restricted embedded systems, is mainly limited by strict power consumption requirements, the cost and the high dependence of DPR techniques with the specific features of the device technology underneath. In this work, we tackle the previously reported problems, designing a reconfigurable platform based on the low-cost and low-power consuming Spartan-6 FPGA family. The full process to develop the platform will be detailed in the paper from scratch. In addition, the implementation of the reconfiguration mechanism, including two profiles, is reported. The first profile is a low-area and low-speed reconfiguration engine based mainly on software functions running on the embedded processor, while the other one is a hardware version of the same engine, implemented in the FPGA logic. This reconfiguration hardware block has been originally designed to the Virtex-5 family, and its porting process will be also described in this work, facing the interoperability problem among different families.

Digital Control Implementation to Reduce the Cost and Improve the Performance of the Control Stage of an Industrial Switched-Mode Power Supply

The main objective of this work is the design and implementation of the digital control stage of a 280W AC/DC industrial power supply in a single low-cost microcontroller to replace the analog control stage. The switch-mode power supply (SMPS) consists of a PFC boost converter with fixed frequency operation and a variable frequency LLC series resonant DC/DC converter. Input voltage range is 85VRMS-550VRMS and the output voltage range is 24V-28V. A digital controller is especially suitable for this kind of SMPS to implement its multiple functionalities and to keep the efficiency and the performance high over the wide range of input voltages. Additional advantages of the digital control are reliability and size. The optimized design and implementation of the digital control stage it is presented. Experimental results show the stable operation of the controlled system and an estimation of the cost reduction achieved with the digital control stage.

Las decisiones de proyecto y los costes de construcción en la vivienda rural, aplicado al estudio de la vivienda autopromovida en la provincia de Cáceres

En la coyuntura actual, en la que existe por un lado, exceso en la oferta de vivienda (de alto precio o de segunda residencia), y aparece por otro demanda de vivienda (de bajo precio y/o social), el mercado inmobiliario se encuentra paradójicamente bloqueado. Así, surge esta investigación como fruto de este momento histórico, en el cual se somete a debate económico el producto vivienda, no solo como consecuencia de la profunda crisis económica, sino también para la correcta gestión de los recursos desde el punto de vista de lo eficiente y sostenible. Se parte de la hipótesis de que es necesario determinar un estimador de costes de construcción de vivienda autopromovida como una de las soluciones a la habitación en el medio rural de Extremadura, para lo cual se ha tomado como modelo de análisis concretamente la Vivienda Autopromovida subvencionada por la Junta de Extremadura en el marco de la provincia de Cáceres. Con esta investigación se pretende establecer una herramienta matemática precisa que permita determinar la inversión a los promotores, el posible margen de beneficios a los contratistas y el valor real de la garantía en el préstamo a las entidades financieras. Pero el objetivo de mayor proyección social de esta investigación consiste en facilitar una herramienta sencilla a la Junta de Extremadura para que pueda establecer las ayudas de una manera proporcional. De este modo se ayuda a optimizar los recursos, lo cual en época de crisis resulta aun más acuciante, ya que conociendo previamente y con bastante exactitud el importe de las obras se pueden dirigir las ayudas de forma proporcional a las necesidades reales de la ejecución. De hecho, ciertas características difíciles de cuantificar para determinar las ayudas en materia de vivienda, como la influencia del número de miembros familiares o la atención a la discapacidad, se verían contempladas de forma indirecta en el coste estimado con el método aquí propuesto, ya que suponen siempre un aumento de las superficies construidas y útiles, de los huecos de fachadas o del tamaño de locales húmedos y por tanto se contemplan en la ecuación del modelo determinado. Por último, contar con un estimador de costes potencia la forma de asentamiento de la construcción mediante autopromocion de viviendas ya que ayuda a la toma de decisiones al particular, subvencionado o no. En efecto, la herramienta es valida en cierta medida para cualquier autopromocion, constituye un sistema de construcción con las menores posibilidades especulativas y lo más sostenible, es abundante en toda Extremadura, y consigue que el sector de la construcción sea un sistema más eficiente al optimizar su proceso económico de producción. SUMMARY Under the present circumstances, in which there is, on one hand, an excess in the supply of housing (high-price or second-home), and on the other hand a demand for housing (low cost and/or social), paradoxically the property market is at a standstill. This research has come about as a result of this moment in time, in which the product: housing, is undergoing economic debate, not only on account of this serious economic crisis, but for the proper management of resources from the point of view of efficiency and sustainability. A building-costs estimator for owner-developed housing is deemed necessary as one of the solutions for the rural environment that is Extremadura. To this end, it is the Owner-Developed House which has been taken as analysis model. It is subsidized by the Extremadura Regional Government in Caceres Province. This research establishes an accurate mathematical tool to work out the developers’ investment, the builder’s potential profit margin and the reality of the loan for the Financial Institution. But the result of most social relevance in this research is to provide the Extremadura Regional Government with a simple tool, so that it can draw up the Subventions proportionally. Thus, the resources are optimized, an even more vital matter in times of economic slump, due to the fact that if the cost of the building works is known with some accuracy beforehand, the subventions can be allocated in a way that is proportional to the real needs of execution. In fact certain elements related to housing subventions which are hard to quantify, such as the influence of number of family members or disability support, would be covered indirectly in cost estimate with the proposed method, since they inevitably involve an increase in built area, exterior wall openings and the size of plumbed rooms. As such they are covered in the determined model equation. Lastly, the availability of a cost-estimator reinforces the ownerdeveloped building model, since it assists decision-making by the individual, whether subsidized or not. This is because the tool is valid to some extent in any owner-development, and this building scheme, which is common in Extremadura, is the most sustainable, and the least liable to speculation. It makes the building sector more efficient by optimizing the economic production process.

La casa crecedera. El crecimiento programado de la vivienda con innovación europea y economía de medios latinoamericana

El concepto de casa crecedera, tal y como lo conocemos en la actualidad, se acuñó por primera vez en 1932 en el concurso Das Wachsende Haus organizado por Martin Wagner y Hans Poelzig dentro del marco de la Exposición Internacional Sonne, Luft und Haus für alle, promovida por la Oficina de Turismo de la ciudad de Berlín. En dicho concurso, se definía este tipo de vivienda como aquella célula básica o vivienda semilla que, dependiendo de las necesidades y posibilidades de los habitantes, podía crecer mediante otras estancias, conformando una vivienda completa en sí misma en cada fase de crecimiento. Numerosos arquitectos de primer orden, tales como Walter Gropius, Bruno Taut, Erich Mendelsohn o Hans Scharoun, participaron en este concurso, abriendo una nueva vía de exploración dentro de la vivienda flexible, la del crecimiento programado. A partir de ese momento, en Europa, y subsecuentemente en EEUU y otras regiones desarrolladas, se iniciaron numerosas investigaciones teóricas y prácticas en torno al fenómeno del crecimiento en la vivienda desde un enfoque vinculado a la innovación, tanto espacial como técnica. Por otro lado, aunque dentro del marco de la arquitectura popular de otros países, ya se ensayaban viviendas crecederas desde el siglo XVIII debido a que, por su tamaño, eran más asequibles dentro del mercado. Desde los años treinta, numerosos países en vías de desarrollo tuvieron que lidiar con migraciones masivas del campo a la ciudad, por lo que se construyeron grandes conjuntos habitacionales que, en numerosos casos, estaban conformados por viviendas crecederas. En todos ellos, la aproximación al crecimiento de la vivienda se daba desde una perspectiva diferente a la de los países desarrollados. Se primaba la economía de medios, el uso de sistemas constructivos de bajo costo y, en muchos casos, se fomentaba incluso la autoconstrucción guiada, frente a las construcciones prefabricadas ensambladas por técnicos especializados que se proponían, por ejemplo, en los casos europeos. Para realizar esta investigación, se recopiló información de estas y otras viviendas. A continuación, se identificaron distintas maneras de producir el crecimiento, atendiendo a su posición relativa respecto de la vivienda semilla, a las que se denominó mecanismos de ampliación, utilizados indistintamente sin tener en cuenta la ubicación geográfica de cada casa. La cuestión de porqué se prefiere un mecanismo en lugar de otro en un caso determinado, desencadenó el principal objetivo de esta Tesis: la elaboración de un sistema de análisis y diagnóstico de la vivienda crecedera que, de acuerdo a determinados parámetros, permitiera indicar cuál es la ampliación o sucesión de ampliaciones óptimas para una familia concreta, en una ubicación establecida. Se partió de la idea de que el crecimiento de la vivienda está estrechamente ligado a la evolución de la unidad de convivencia que reside en ella, de manera que la casa se transformó en un hábitat dinámico. Además se atendió a la complejidad y variabilidad del fenómeno, sujeto a numerosos factores socio-económicos difícilmente previsibles en el tiempo, pero fácilmente monitorizables según unos patrones determinados vinculados a la normatividad, el número de habitantes, el ahorro medio, etc. Como consecuencia, para el diseño del sistema de optimización de la vivienda crecedera, se utilizaron patrones evolutivos. Dichos patrones, alejados ya del concepto espacial y morfológico usualmente utilizado en arquitectura por figuras como C. Alexander o J. Habraken, pasaron a entenderse como una secuencia de eventos en el tiempo (espaciales, sociales, económicos, legales, etc.), que describen el proceso de transformación y que son peculiares de cada vivienda. De esta manera, el tiempo adquirió una especial importancia al convertirse en otro material más del proyecto arquitectónico. Fue en la construcción de los patrones donde se identificaron los mencionados mecanismos de ampliación, entendidos también como sistemas de compactación de la ciudad a través de la ocupación tridimensional del espacio. Al estudiar la densidad, mediante los conceptos de holgura y hacinamiento, se aceptó la congestión de las ciudades como un valor positivo. De esta forma, las posibles transformaciones realizadas por los habitantes (previstas desde un inicio) sobre el escenario del habitar (vivienda semilla), se convirtieron también en herramientas de proyecto urbano que responden a condicionantes del lugar y de los habitantes con distintas intensidades de crecimiento, ocupación y densidad. Igualmente, en el proceso de diseño del sistema de optimización, se detectaron las estrategias para la adaptabilidad y transformación de la casa crecedera, es decir, aquella serie de acciones encaminadas a la alteración de la vivienda para facilitar su ampliación, y que engloban desde sistemas constructivos en espera, que facilitan las costuras entre crecimiento y vivienda semilla, hasta sistemas espaciales que permiten que la casa altere su uso transformándose en un hábitat productivo o en un artefacto de renta. Así como los mecanismos de ampliación están asociados a la morfología, se descubrió que su uso es independiente de la localización, y que las estrategias de adaptabilidad de la vivienda se encuentran ligadas a sistemas constructivos o procesos de gestión vinculados a una región concreta. De esta manera, la combinación de los mecanismos con las estrategias caracterizan el proceso de evolución de la vivienda, vinculándola a unos determinados condicionantes sociales, geográficos y por tanto, constructivos. Finalmente, a través de la adecuada combinación de mecanismos de ampliación y estrategias de adaptabilidad en el proyecto de la vivienda con crecimiento programado es posible optimizar su desarrollo en términos económicos, constructivos, sociales y espaciales. Como resultado, esto ayudaría no sólo a mejorar la vida de los habitantes de la vivienda semilla en términos cualitativos y cuantitativos, sino también a compactar las ciudades mediante sistemas incluyentes, ya que las casas crecederas proporcionan una mayor complejidad de usos y diversidad de relaciones sociales. ABSTRACT The growing house concept -as we currently know it- was used for the first time back in 1932 in the competition Das Wachsende Haus organized by Martin Wagner and Hans Poelzig during the International Exhibition Sonne, Luft und Haus für alle, promoted by Berlin's Tourist Office. In that competition this type of housing was defined as a basic cell or a seed house unit, and depending on the needs and capabilities of the residents it could grow by adding rooms and defining itself as a complete house unit during each growing stage. Many world-top class architects such as Walter Gropius, Bruno Taut, Erich Mendelsohn or Hans Scharoun, were part of this competition exploring a new path in the flexible housing field, the scheduled grownth. From that moment and on, in Europe -and subsequently in the USA and other developed areas- many theorical and pragmatical researchs were directed towards the growing house phenomena, coming from an initial approach related to innovation, spacial and technical innovation. Furthermore -inside the traditional architecture frame in other countries, growing houses were already tested in the XVIII century- mainly due to the size were more affordable in the Real State Market. Since the 30's decade many developing countries had to deal with massive migration movements from the countryside to cities, building large housing developments were -in many cases- formed by growing housing units. In all of these developing countries the growing house approach was drawn from a different perspective than in the developed countries. An economy of means was prioritized, the utilization of low cost construction systems and -in many cases- a guided self-construction was prioritized versus the prefabricated constructions set by specialized technics that were proposed -for instance- in the European cases. To proceed with this research, information from these -and other- housing units was gathered. From then and on different ways to perform the growing actions were identified, according to its relative position from the seed house unit, these ways were named as addition or enlargement mechanisms indifferently utilized without adknowledging the geographic location for each house. The question of why one addition mechanism is preferred over another in any given case became the main target of this Thesis; the ellaboration of an analysis and diagnosis system for the growing house -according to certain parameters- would allow to point out which is the addition or addition process more efficient for a certain family in a particular location. As a starting point the grownth of the housing unit is directly linked to the evolution of the family unit that lives on it, so the house becomes a dynamic habitat. The complexity and the variability of the phenomena was taken into consideration related to a great number of socio-economic factors hardly able to be foreseen ahead on time but easy to be monitored according to certain patterns linked to regulation, population, average savings, etc As a consequence, to design the optimization system for the growing house, evolutionary patterns were utilized. Those patterns far away from the spatial and morphologic concept normally utilized in Architecture by characters like C. Alexander or J. Habraken, started to be understood like a sequence of events on time (spatial events, social events, economic events, legal events, etc) that describes the transformation process and that are particular for each housing unit. Therefore time became something important as another ingredient in the Architectural Project. The before mentioned addition or enlargement mechanisms were identified while building the patterns; these mechanisms were also understood as city's system of compactation through the tridimendional ocupation of space. Studying density, thorough the concepts of comfort and overcrowding, traffic congestion in the city was accepted as a positive value. This way, the possible transformations made by the residents (planned from the begining) about the residencial scenary (seed house), also became tools of the urban project that are a response to site's distinctive features and to the residents with different grownth intensities, activities and density Likewise, during the process of designing the optimization system, strategies for adaptations and transformation of the growing house were detected, in other words, the serial chain of actions directed to modify the house easing its enlargement or addition, and that comprehends from constructive systems on hold -that smooths the costures between grownth and housing seed- to spatial systems that allows that the house modify its utilization, becoming a productive habitat or a rental asset. Because the enlargement mechanisms are linked to the morphology, it was discovered that the use it's not related to the location, and that the adaptation strategies of the houses are linked to constructive systems or management processes linked to a particular area. This way the combination of mechanisms and strategies characterizes the process of housing evolution, linking it to certain social and geographic peculiarities and therefore constructives. At last, through the certain combination of enlargement mechanisms and adaptability strategies in the housing with scheduled grownth project is possible to optimize its development in economic, constructive, social and spatial terms. As a result, this would help not only to improve the life of the seed house residents in qualitative and quantitative terms but also to compact the cities through inclusive systems, given that the growing houses provide a larger complexity of uses and social relations.