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  • Open access
  • 42 Reads
AUTOMATED LEAK DETECTION SYSTEM FOR THE IMPROVEMENT OF WATER NETWORK MANAGEMENT

The need for an efficient Water Management System (WMS) is strongly felt by water utilities, municipalities and by medium to large scale corporates that have to face every day with problems dealing with water usage and supply. Leveraging a sensor data network, an automated system to implement fault detection in a water network at an early stage can be a valuable tool that saves water, energy, time and money. The paper introduces a novel FDD approach for water networks developed within the FP7 Waternomics Project by modeling a water network in the simulation environment EPANET and applying an anomaly detection algorithm named ADWICE to real time data of water flow and pressure to infer performance and operational anomalies. The method is currently being implemented at the Linate Airport water network in Milan, and the results will be presented in the paper. The paper will also show how the same EPANET model can be integrated in a web based Decision Support System to help water network managers in defining optimal and demand based pressure management in order to reduce water leaks by reducing pressure where and when possible.

  • Open access
  • 18 Reads
Consensus-based cooperative-control approach applied to urban traffic networks

Nowadays, many investigations actively pursue improvements in the performance of urban traffic networks. A central challenge is the need for cooperation between different parts of these networks such as vehicles and infrastructural systems. In this study, an algorithm for cooperative control of urban subsystems is applied to an alternative solution for mobility-related problems in cities. Thus, interconnected networks of traffic-light controllers (TLC) adapt traffic-light cycles, in order to decrease the concentration of air pollutants based on information from traffic-monitoring and pollution-monitoring systems in the city. The presence of atmospheric pollution in cities is not only caused by road traffic, but also by other sources of pollutants that contribute to rising or falling levels of atmospheric pollution. The complexity of the problem increases, due to the distributed and the heterogeneous nature of the different components. A design method based on a system-of-systems engineering approach is applied to the distributed consensus-based control algorithm. The control law that is applied contains a consensus-based component that processes data shared over the network to achieve consensus-based cooperative control over the TLC network components. Furthermore, Discrete Event Systems Specification (DEVS) formalism is applied for modeling and simulation purposes. The results of testing and validating the proposed solution in a simulated environment corroborate its powerful capacity to coordinate simultaneous responses to both pollution levels and traffic flows in urban traffic networks.

  • Open access
  • 29 Reads
Heterocyclic dicyanovinyl derivatives: synthesis and evaluation of the chemosensory ability in aqueous solution

The cyanide anion is well known due to its toxicity to the environment and to mammals, leading to convulsions, loss of consciousness, and eventual death. It is lethal to humans for concentrations in the range of 0.5-3.5 mg per Kg of body weight. In addition to being found in many foods and plants, cyanides are used industrially in the synthesis of organic chemicals, polymers, metallurgy as well as in gold mining [1].

Consequently, selective detection and quantification of cyanide is very important and it has been the object of increasing investigation. A large number of fluorimetric and/or colorimetric chemosensors as well as dosimeters, capable of detecting this anion in organic solvent as well as in aqueous mixtures have been reported during the last decade. Even so, the majority suffer from several drawbacks such as difficult synthesis, poor selectivity, only work in an organic media and the use of instrumentation is required [2]. Therefore, the research on versatile and tunable chemosensors capable of selective and sensitive colorimetric sensing of the cyanide anion, especially in mixed aqueous solutions, is still a challenge [3].

In this communication, we report the synthesis, characterization and evaluation of the photophysical properties and the chemosensory ability of novel receptors based on benzofuran and benzoindole systems functionalized with the dicyanovinyl group. The new compounds were synthesized in good yields through Knoevenagel reaction between the precursor aldehydes and malononitrile.

The photophysical properties of the new push-pull systems were studied by UV-vis and fluorescence spectroscopy in acetonitrile. The evaluation of the compounds as colorimetric chemosensors was carried out by performing spectrophotometric titrations in acetonitrile and acetonitrile/water in the presence of relevant organic and inorganic anions, and of alkaline, alkaline-earth and transition metal cations. The benzoindole derivative exhibited great selectivity for the cyanide anion over other anions in acetonitrile/water (8:2) solution showing a distinct color change from colorless to yellow.

 

Acknowledgements: Thank are due to Fundação para a Ciência e Tecnologia (Portugal) and FEDER-COMPETE for financial support through Centro de Química (PEst-C/QUI/UI0686/2013 (FCOMP-01-0124-FEDER-037302)), and a PhD grant to R.C.M. Ferreira (SFRH/BD/86408/2012). The NMR spectrometer Bruker Avance III 400 is part of the National NMR Network and was purchased with funds from FCT and FEDER.

 

References:

  1. a) Vennesland, B.; Comm, E. E.; Knownles, C. J.; Westly, J.; Wissing, F. in Cyanide in Biology, Academic Press, London, 1981. b) Ullmann’s Encyclopedia of Industrial Chemistry, 6th edn, Wiley-VCH, New York, 1999. c) Muir, G. Hazards in The Chemical laboratory, Royal Chemical Society, London 1977. d) Baskin, S. I.; Brewer, T. G. in Medical Aspects of Chemical and Biological Warfare, Eds. Sidel, F.; Takafuji, E. T.; Franz, D. R. TMM Publications, Washington DC, 1997, pp. 271.
  2. Xu, Z.; Chen, X.; Kim, H. N.; Yoon, J. Chem. Soc. Rev. 2010, 39, 127.
  3. For some recent examples reported by our group see: a) Batista, R. M. F.; Costa, S. P. G.; Raposo, M. M. M. Sensors Actuators B 2014, 191, 791. (b) Batista, R. M. F.; Oliveira, E.; Costa, S. P. G.; Lodeiro, C.; Raposo, M. M. M. Supramol. Chem. 2014, 26, 71. (c) Batista, R. M. F.; Costa, S. P. G.; Raposo, M. M. M. J. Photochem. Photobiol. Chem. A 2013, 259, 733. (d) Santos-Figueroa, L. E.; Moragues, M. E.; Raposo, M. M. M., Batista, R. M. F.; Ferreira, R. C. M.; Costa, S. P. G.; Sancenón, F.; Martínez-Máñez, R.; Ros-Lis, J. V.; Soto, J. Org. Biomol. Chem. 2012, 10, 7418. (e) Santos-Figueroa, L. E.; Moragues, M. E.; Raposo, M. M. M., Batista, R. M. F.; Ferreira, R. C. M.; Costa, S. P. G.;  Sancenón, F.; Martínez-Máñez, R.; Ros-Lis, J. V.; Soto, J. Tetrahedron 2012, 68, 7179. (f) Raposo, M. M. M.; García-Acosta, B.; Ábalos, T.; Calero; P.; Martínez-Manez, R.; Ros-Lis, J. V.; Soto, J. J. Org. Chem. 2010, 75, 2922.
  • Open access
  • 50 Reads
Proximity and Contact Sensing with Instrumented Compliant Wrist for Close Guidance of Robotic Manipulators

Compliance in robotic systems has been exploited to allow rigid mechanisms to come into contact with complex and possibly fragile objects. By incorporating compliance and instrumentation into a single device nearby objects can be detected before direct contact occurs. That way, safer and smoother robot guidance can be achieved both while approaching and while touching surfaces. Furthermore, the path planning and control problem is simplified as position based algorithms can be used regardless of the state of system, be it in free motion or constrained motion, or even during transitions between the two modes. This paper presents the design and experimental validation of a lightweight, low-cost and stand-alone instrumented compliant wrist mechanism which can be mounted on the tool plate of any rigid robotic manipulator. Embedded arrays of infrared sensors provide distance measurements. Each is finely tuned via a novel calibration procedure that overcomes inter-sensor variability. All signal processing is also embedded and wireless transmission connects the device to the robot controller to support path control. Real-time acquired measurements on the position and orientation of surfaces located in close proximity or in contact with the robot’s end effector permit close guidance of its operation. Experimental work demonstrates how the device provides physical compliance to prevent large impact forces to occur during non-contact to contact transitions by the manipulator’s end effector. It also demonstrates the stability and accuracy of the device outputs. Primary applications of the proposed instrumented compliant wrist include smooth surface following in manufacturing and safe human-robot interaction.

  • Open access
  • 70 Reads
On the use of PZT-patches as exciters in modal analysis: Application to submerged structures

Modal analysis is an experimental technique widely used to determine the dynamic response of structures. One of the most critical part is the selection of the actuator that will excite the tested structure.In many cases traditional exciters, such as hammers and shakers, have been used for this purpose. Nevertheless, these exciters may have the disadvantage of modifying the modal parameters (as reported in some cases) and they are difficult to be used when the structure is not accessible (confined and/or submerged).For these cases PZT-patches, that are very light structures (compared to the tested structure), have been recently used as exciters. Although, in the analyzed studies the natural frequencies of the structure have been determined using PZTs, the rest of parameters that determine the FRF (Frequency response Function) are not obtained. This could be, because the calibration of PZTs as dynamic force transducers is a complicated task and is not an information given by the manufacturers, as in other exciters used for the same purpose.This paper analyzes experimentally and analytically the use of PZT-patches as exciters for modal analysis. For this purpose, a tested structure is excited in different ways with a PZT and its response compared with a reference case, obtained with a classical exciter. Analyses show how to obtain different modal parameters that determine the FRF of the structure, without previous calibration of the PZT. Finally, and in order to show the potential advantages of these exciters for inaccessible structures, the procedure is repeated for the same structure submerged, showing that PZT are much more appropriated exciters in these cases.  

  • Open access
  • 23 Reads
Development and testing of a Dual Accelerometer Vector Sensor for AUV acoustic surveys

This paper presents the design, manufacturing and testing of a Dual Accelerometer Vector
Sensor (DAVS). The device was built within the activities of the WiMust project, a 
European Commission  project, supported under the Horizon 2020 Framework Programme,
which aims to improve the efficacy of the methodologies used to perform geophysical
acoustic surveys at sea by the use of Autonomous Underwater Vehicles (AUVs) . The DAVS
contributes to this aim  in various ways, for example,  owing to its spatial filtering
capability, it can measure reflections at the desired direction therefore reducing the
amount of post processing related to deghosting and multipath removal. Also its compact
size allows easier integration with AUVs and hence facilitates the vehicle
maneuverability compared to the classical towed arrays. The DAVS device consists of two
tri-axial accelerometers and one hydrophone molded in one unit. The device's directional
estimation capabilities were evaluated on an AUV, which was sailing around a deployed
sound source. Results of this experiment are presented in this paper.

  • Open access
  • 14 Reads
Assessment of micromechanically-induced uncertainties in the electromechanical response of MEMS devices

Microelectromechanical systems (MEMS) have been already successfully commercialized for around 20 years. The design of novel MEMS sensors currently target two important features: smaller dimensions and higher reliability. As the characteristic size of the mechanical components of the devices decreases, uncertainties in the mechanical and geometrical properties induced by the microfabrication process become more and more important. To address these issues, an on-chip testing device has been proposed by the authors to avoid any visual inspection for the read-out. As the device has been obtained with a standard MEMS fabrication process, the experimentally tested conditions can be rather similar to those featured by the application systems. The spreading of the mentioned mechanical and geometrical features has been assessed thanks to a thin micro-cantilever, so as to magnify the effects of the microstructure on the overall MEMS behavior.

The electromechanical responses of ten nominally identical specimens have been recorded, and experimental data have shown a significant scattering due to the presence of the relevant uncertainty sources. To interpret the response of the device, an analytical reduced-order model and a finite element model of the whole device have been developed. The effects of random film morphology and of (over)etch depth have been then assessed through a Monte Carlo analysis. A genetic algorithm has been eventually adopted to identify features of the probability distributions of the mechanical and geometrical uncertainties in the batch of test structures.

  • Open access
  • 30 Reads
A multiscale approach to the smart deployment of micro-sensors over flexible plates

In former studies, we proposed a topology optimization approach to maximize the sensitivity to damage of measurements collected through a network of sensors deployed over flexible, thin plates. Within such frame, a damage must be intended as a change of the structural health characterized by a reduction of the relevant load-carrying capacity. By properly comparing the response of the healthy, undamaged structure and the response of the damaged one, independently of the location of the source of damage, a procedure to optimally deploy a given set of sensors was provided.

In this work we extend the aforementioned approach within a multi-scale frame, to account for (at least) three different length-scales: a macroscopic one, linked to the dimensions of the structure to be monitored; a mesoscopic one, linked to the characteristic size of the damaged region(s); a microscopic one, linked to the size of inertial microelectromechanical systems (MEMS) to be used within a marginally invasive health monitoring system. Results are provided for a square plate simply supported along its border, to show how the micro-sensors are to be deployed to maximize the sensitivity of measurements to damage, and to also discuss the speedup obtained with the proposed multiscale approach in comparison with a standard single-scale one.

  • Open access
  • 19 Reads
Optimal sensor placement through Bayesian experimental design: effect of measurement error and number of sensors

Sensors networks for the health monitoring of structural systems have to be designed to achieve both accurate estimations of the relevant mechanical parameters and low cost of the experimental equipment. Therefore, the number, type and location of the sensors have to be chosen so that the uncertainties related to the estimated health are minimized. Several deterministic methods based on the sensitivity of measures with respect to the parameters to be tuned are widely used; despite their low computational cost, these methods do not take into account the uncertainties related to the measurement process.

In former studies, a method based on the maximization of the information associated with the available measurements has been proposed and the use of approximate solutions has been extensively discussed. Here we propose a robust numerical procedure to solve the optimization problem: in order to reduce the computational cost of the overall procedure, Polynomial Chaos Expansion and a stochastic optimization method are employed.

The method is applied to a flexible plate. First of all, we investigate how the information changes with the number of sensors; then we analyze the effect of choosing different types of sensors (with their relevant accuracy) on the information provided by the structural health monitoring system.

  • Open access
  • 26 Reads
Challenges in Wireless SystemIntegration in the Implementation of Smart City Environments

The advent of Internet of Things and the evolution of wireless communication systems (towards 4G and 5G systems, as well as wireless sensor networks) is leading towards the implementation of context aware environments. The adoption of such scenarios requires intensive effort in order to optimize coverage/capacity relations, reducing interference and hence, providing optimal Quality of Service and minimum energy consumption. In this work, some of these challenges in relation with wireless system integration, as well as Context Aware scenario examples will be described.

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