Leakage detection in water pipe networks using electromechanical impedance (EMI) based technique

The electromechanical impedance (EMI) technique has been successfully used in structural health monitoring (SHM) systems on a wide variety of structures. The basic concept of this technique is to monitor the structural integrity by exciting and sensing a piezoelectric transducer, usually a lead zirconate titanate (PZT) wafer bonded to the structure to be monitored and excited in a suitable frequency range. Because of the piezoelectric effect, there is a relationship between the mechanical impedance of the host structure, which is directly related to its integrity, and the electrical impedance of the PZT transducer, obtained by a ratio between the excitation and the sensing signals.This work presents a study on damage (leaks) detection using EMI based method. Tests were carried out in a rig water system built in a Hydraulic Laboratory for different leaks conditions in a metallic pipeline. Also, it was evaluated the influence of the PZT position bonded to the pipeline. The results show that leaks can effectively be detected using common metrics for damage detection such as RMSD and CCDM. Further, it was observed that the position of the PZT bonded to the pipes is an important variable and has to be controlled.

Phenomenological model for the interpretation of impedance/admittance spectroscopy results in polymer light-emitting electrochemical cells

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Impedance-derived electrochemical capacitance spectroscopy for the evaluation of lectin-glycoprotein binding affinity

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Lumped element modeling of operational structures by inverting the mobility models

This paper is concerned with what a source precisely sees when it drives a receiver such as a continuous structural object. An equivalent lumped element system consisting of masses, springs and dampers is developed to visually represent the operational structural dynamics of a single-input structure at the driving point. The development is solely based on the mobility model of the driving point response. The mobility model is mathematically inverted to give the impedance model that is suitable for lumped element modeling. The two types of structures studied are unconstrained inertial objects and constrained resilient objects. The lumped element systems presented suggest a new view to dynamics that a single-input flexible structure in operation can be decomposed into the two subsystems: a base system of single degree of freedom (or of a mass for an inertial object) whose mass is in contact with the source and an appendage system consisting of a series of oscillators each of which is attached to the base mass. The driving point response is a result of the coupling between the two subsystems. (C) 2014 Elsevier Ltd. All rights reserved.

FINITE ELEMENT SIMULATIONS FOR THE COMPREHENSION OF PHYSICAL PHENOMENA INVOLVED IN ELECTRIC IMPEDANCE TOMOGRAPHY OF MASONRY STRUCTURES

The paper describes the preliminary studies of University of Minho on the use of Electric Impedance/Resistance Tomography to assess masonry structures. The study is focused on the analysis of values of current and voltage resulting from the use of an electrical source with voltage and frequency values from a distribution network. The analysis is made from results obtained through computer simulations, using a three-dimensional model of the idealized masonry structures. A finite element program was used for the simulations. Three types of electrodes were used in simulations, and the analysis of the results led to significant conclusions. Later masonry specimens were built and a series of preliminary tests were carried out in the laboratory. The comparative analysis of simulated and experimental results allowed identifying the factors that have influence on the physical results.

Design and implementation of wireless sensor networks for impedance-based structural health monitoring using ZigBee and Global System for Mobile Communications

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Piezoelectric transducers assessed by the pencil lead break for impedance-based structural health monitoring

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Grinding process monitoring based on electromechanical impedance measurements

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Pitahaya aging diagnostic by impedance/capacitance spectroscopy

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Complementary study on the electrical and structural properties of poly(3-alkylthiophene) and its copolymers synthesized on ITO by electrochemical impedance and Raman spectroscopy

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Electrochemical studies of copper, copper-aluminium and copper-aluminium-silver alloys: Impedance results in 0.5M NaCl

The electrochemical behaviour of Cu, Cu-Al and Cu-Al-Ag alloys in aqueous solutions of NaCl (0.5 M, pH = 3.00) was studied by means of voltammetric methods and electrochemical impedance spectroscopy. The surfaces were examined by SEM and EDX analysis. Cu-Al-Ag alloy shows a potentiodynamic behaviour similar to that of the pure copper electrode while the Cu-Al alloy presents some minor differences. In the active dissolution region the electrodes suffer pitting corrosion and in the other potential regions there are the formation of a passivant film with composition depending on the potential. The impedance responses of the electrodes are discussed. An electrodissolution mechanism is proposed and the effect of the alloying elements upon the impedance response and polarisation curves is explained. The main effects are due to the production of copper and silver chlorides and aluminium oxides/ hydroxides at the corroding interface. The addition of Al or (Al + Ag) increases the corrosion resistance of pure copper. © 1995.

A Study of Interdisciplinary Research Needs: Results from Input of Faculty in Six Engineering Departments in Prioritizing Serial Subscriptions

Baldwin, Virginia (2003) "A Study of Interdisciplinary Research Needs: Results from Input of Faculty in Six Engineering Departments in Prioritizing Serial Subscriptions," American Society for Engineering Education Conference, June 23, 2003, Nashville, TN,

Distribution of sewage input in marine sediments around a maritime Antarctic research station indicated by molecular geochemical indicators

Sediments from Admiralty Bay, Antarctica were collected during the austral summers of 2002/2003 and 2003/2004 in order to assess the distribution and concentration of sewage indicators originating from Comandante Ferraz Brazilian Antarctic Station. Fecal sterols (coprostanol + epicoprostanol) and linear alkylbenzenes (LABs) ranged from <0.01 to 0.95 mu g g(-1) and <1.0 to 23 ng g(-1) dry weight, respectively. In general, the higher concentrations were found only locally in the vicinity of Ferraz station at Martel Inlet. Baseline values for fecal sterols and coprostanone were calculated as 0.19 and 0.40 mu g g(-1), respectively. According to fecal sterols concentrations, sewage contribution to Martel Inlet has increased more than twice since 1997, as result of the increase in the number of researchers at the station especially during the last decade. A low correlation was found between total LABs and fecal steroids, which could be attributed to the contribution of the natural sources of steroids. (C) 2010 Elsevier B.V. All rights reserved.

No evidence of UV cone input to mono- and biphasic horizontal cells in the goldfish retina

Many animal species make use of ultraviolet (UV) light in a number of behaviors, such as feeding and mating. The goldfish (Carassius auratus) is among those with a UV photoreceptor and pronounced UV sensitivity. Little is known, however, about the retinal processing of this input. We addressed this issue by recording intracellularly from second-order neurons in the adult goldfish retina. In order to test whether cone-driven horizontal cells (HCs) receive UV cone inputs, we performed chromatic adaptation experiments with mono- and biphasic HCs. We found no functional evidence of a projection from the UV-sensitive cones to these neurons in adult animals. This suggests that goldfish UV receptors may contact preferentially triphasic HCs, which is at odds with the hypothesis that all cones contact all cone-driven HC types. However, we did find evidence of direct M-cone input to monophasic HCs, favoring the idea that cone-HC contacts are more promiscuous than originally proposed. Together, our results suggest that either UV cones have a more restricted set of post-synaptic partners than the other three cone types, or that the UV input to mono- and biphasic HCs is not very pronounced in adult animals.

Segregated anatomical input to sub-regions of the rodent superior colliculus associated with approach and defense

The superior colliculus (SC) is responsible for sensorimotor transformations required to direct gaze toward or a way from unexpected, biologically salient events. Significant changes in the external world are signaled to SC through primary multisensory afferents, spatially organized according to a retinotopic topography. For animals, where anunexpected event could indicate the presence of either predator or prey, early decisions to approach or avoid are particularly important. Rodents' ecology dictates predators are most often detected initially as movements in upper visual field (mapped in medial SC), while appetitive stimuli are normally found in lower visual field (mapped in lateral SC). Our purpose was to exploit this functional segregation to reveal neural sites that can bias or modulate initial approach or avoidance responses. Small injections of Fluoro-Gold were made into medial or lateral sub-regions of intermediate and deep layers of SC (SCm/SCl). A remarkable segregation of input to these two functionally defined areas was found. (i) There were structures that projected only to SCm (e.g., specific cortical areas, lateral geniculate and suprageniculate thalamic nuclei, ventromedial and premammillary hypothalamic nuclei, and several brain-stem areas) or SCl (e.g., primary somatosensory cortex representing upper body parts and vibrissae and parvicellular reticular nucleus in the brainstem). (ii) Other structures projected to both SCm and SCl but from topographically segregated populations of neurons (e.g., zona incerta and substantia nigra pars reticulata). (iii) There were a few brainstem areas in which retrogradely labeled neurons were spatially overlapping (e.g., pedunculopontine nucleus and locus coeruleus). These results indicate significantly more structures across the rat neuraxis are in a position to modulate defense responses evoked from SCm, and that neural mechanisms modulating SC-mediated defense or appetitive behavior are almost entirely segregated.