Low-Cost Piezoelectric Sensors for Time Domain Load Monitoring of Metallic Structures During Operational and Maintenance Processes

The versatility of piezoelectric sensors in measurement techniques and their performance in applications has given rise to an increased interest in their use for structural and manufacturing component monitoring. They enable wireless and sensor network solutions to be developed in order to directly integrate the sensors into machines, fixtures and tools. Piezoelectric sensors increasingly compete with strain-gauges due to their wide operational temperature range, load and strain sensing accuracy, low power consumption and low cost. This research sets out the use of piezoelectric sensors for real-time monitoring of mechanical strength in metallic structures in the ongoing operational control of machinery components. The behaviour of aluminium and steel structures under flexural strength was studied using piezoelectric sensors. Variations in structural behaviour and geometry were measured, and the load and μstrains during operational conditions were quantified in the time domain at a specific frequency. The lead zirconium titanate (PZT) sensors were able to distinguish between material types and thicknesses. Moreover, this work covers frequency selection and optimisation from 20 Hz to 300 kHz. Significant differences in terms of optimal operating frequencies and sensitivity were found in both structures. The influence of the PZT voltage applied was assessed to reduce power consumption without signal loss, and calibration to μstrains and loads was performed.This research was funded by Basque Government, grant number KK-2019/00051-SMARTRESNAK and by the European Commission, grant number 869884- RECLAIM

Productividad de las empresas emergentes y su capacidad exportadora en el sector textil de Carabayllo, 2019

La siguiente investigación tiene como título “Productividad de las empresas emergentes y su capacidad exportadora en el sector textil de Carabayllo, 2019” el cual tiene como problema general ¿Qué relación existe entre la Productividad de las empresas emergentes y su capacidad exportadora en el sector textil de Carabayllo, 2019? Asimismo, tiene como principal objetivo el identificar qué relación existe entre ambas variables. Para el desarrollo de la siguiente investigación fue necesaria la recopilación de información en campo, para ello se utilizó como instrumento cuestionarios dirigidas a empresas textileras situadas en el distrito de Carabayllo. En la presente investigación se busca optimizar diversas dimensiones de la productividad para que así permitan desarrollar la capacidad exportadora de las empresas emergentes, ya que en la actualidad es un punto poco desarrollado. Con los resultados obtenidos se determina que la productividad de las empresas textileras de Carabayllo se relaciona positivamente con su capacidad exportadora, ya que en el periodo 2019 el 36.8% de empresas tiene un alto nivel de productividad

On Mechanical and Electrical Coupling Determination at Piezoelectric Harvester by Customized Algorithm Modeling and Measurable Properties

Piezoelectric harvesters use the actuation potential of the piezoelectric material to transform mechanical and vibrational energies into electrical power, scavenging energy from their environment. Few research has been focused on the development and understanding of the piezoelectric harvesters from the material themselves and the real piezoelectric and mechanical properties of the harvester. In the present work, the authors propose a behavior real model based on the experimentally measured electromechanical parameters of a homemade PZT bimorph harvester with the aim to predict its Vrms output. To adjust the harvester behavior, an iterative customized algorithm has been developed in order to adapt the electromechanical coupling coefficient, finding the relationship between the harvester actuator and generator behavior. It has been demonstrated that the harvester adapts its elongation and its piezoelectric coefficients combining the effect of the applied mechanical strain and the electrical behavior as a more realistic behavior due to the electromechanical nature of the material. The complex rms voltage output of the homemade bimorph harvester in the frequency domain has been successfully reproduced by the proposed model. The Behavior Real Model, BRM, developed could become a powerful tool for the design and manufacturing of a piezoelectric harvester based on its customized dimensions, configuration, and the piezoelectric properties of the smart materials.This research was funded by the Basque Government, grant number KK-2021/00082-µ4IIoT, and by the European Commission, grant number 869884- RECLAIM

PREVALENCIA DE LA HIPERTENSION PULMONAR COMO COMPLICACION EN PACIENTES CON ENFERMEDAD RENAL CRONICA TERMINAL EN HEMODIALISIS EN EL HOSPITAL GENERAL DE ECATEPEC “DR. JOSE MARIA RODRIGUEZ”

RESUMEN ANTECEDENTES: La Enfermedad Renal Crónica presenta múltiples complicaciones Cardiovasculares y de estas una de las menos estudiadas es la HIPERTENSION PULMONAR, la cual se presenta más aun en los pacientes con terapia sustitutiva de Hemodiálisis. MATERIAL Y METODOS: Se realizó un estudio Descriptivo, Retrospectivo y Transversal. En base al estudio de 46 pacientes que se encuentran con el diagnostico de Enfermedad Renal Crónica Terminal en terapia sustitutiva de la función renal a base de Hemodiálisis a los cuales se les realizo un Ecocardiograma Transtoracico Tisular y Pulsado para valorar la existencia de hipertensión pulmonar. RESULTADOS: De los 46 pacientes en Hemodiálisis, solo uno fue excluido del estudio por presentar datos compatibles con hipocinesia miocardica, así un total de 45 estudios fueron incluidos. Se reporta que 13 pacientes (19.11%) No presentaron hipertensión Pulmonar y que 55 pacientes (80.88%) presentaron hipertensión pulmonar, de los cuales 41 pacientes (74.54%%) siendo hipertensión Pulmonar Leve, 11 pacientes (20%) de hipertensión Pulmonar Moderada y 3 paciente (5.45%) de hipertensión Pulmonar Severa. CONCLUSIONES: De los pacientes de la Unidad de Hemodiálisis del Hospital General de Ecatepec “Dr. José María Rodríguez” un alto porcentaje (Incidencia) presentan hipertensión pulmonar y que estos se encuentran Sub-diagnosticados

From Porciones to Colonias: Curriculum Development in K-12 Education--Methodology and Program Development

The 2012 National Endowment for the Humanities- sponsored “From Porciones to Colonias: Inserting the “Hispanic” in a Hispanic Serving Institution through Curriculum Innovation” brought together faculty at the largest Hispanic Serving Institution in Texas, the University of Texas-Pan American (UTPA), and public school teachers to create place-based curriculum. Using the natural landscape and cultural history of one of the most dynamic borderlands in the world as the main classroom laboratory, faculty housed in the CHAPS program (Community Historical Archaeology Project with Schools) challenged elementary, middle, and high school teachers in the sciences, social sciences and humanities to create in their students historically literate citizens who are aware of their local cultural and natural history. The following briefly encapsulates the conducted activities

Electrical Response Analysis of a Piezoelectric Energy Harvester Power Source Based on Electromechanical Parameters

A piezoelectric energy harvester generator is a device capable of transforming environmental mechanical energy into electrical energy. The piezoelectric electromechanical parameters determine the maximum electrical power which is able to be transferred to an electric load. In this research work, an exhaustive study of the electromechanical parameters related to the piezoelectric material is carried out, modeling them as components of an electrical circuit, in order to analyze their influence on the transmitted power. On the other hand, some electrical loads are simulated to determine different matrix scenarios for a model developed by state-space equations in the Laplace transform domain. The results obtained have allowed to know how the piezoelectric material properties and mechanical characteristics influence the electrical power output of the energy harvester generator and the energy transmission behavior for different electric loads. The conclusions show how the different electromechanical parameters are related to each other, and how their combination transforms the mechanical environmental energy into the required electrical energy. The novelty of this research is the presentation of a model capable of obtaining the optimized working point of the harvester, taking into account not only the electric loads and current demands but also the piezoelectric material parameters.This research was funded by the European Commission, grant number 869884-RECLAIM

In Vivo Corneal Microstructural Changes in Herpetic Stromal Keratitis: A Spectral-Domain Optical Coherence Tomography Analysis

Purpose: To describe and analyze the microstructural changes in herpetic stromal keratitis (HSK) observed in vivo by spectral-domain ocular coherence tomography (SD-OCT) at different stages of the disease. Methods: A prospective, cross-sectional, observational, and comparative SD-OCT analysis of corneas with active and inactive keratitis was performed, and the pathologic differences between the necrotizing and non-necrotizing forms of the disease were analyzed. Results: Fifty-three corneas belonging to 43 (81.1%) women and 10 (18.8%) men with a mean age of 41.0 years were included for analysis. Twenty-four (45.3%) eyes had active keratitis, and 29 (54.7%) had inactive keratitis; the majority (83.0%) had the non-necrotizing form. Most corneas (79.1%) with active keratitis showed stromal edema and inflammatory infiltrates. Almost half of the active lesions affected the visual axis, were found at mid-stromal depth, and had a medium density. By contrast, corneas with inactive keratitis were characterized by stromal scarring (89.6%), epithelial remodeling (72.4%), and stromal thinning (68.9%). In contrast to non-necrotizing corneas, those with necrotizing HSK showed severe stromal scarring, inflammatory infiltration, and thinning. Additionally, most necrotizing lesions (77.7%) affected the visual axis and had a higher density (P = 0.010). Conclusion: Active HSK is characterized by significant epithelial and stromal thickening and the inactive disease manifests epithelial remodeling at sites of stromal thinning due to scarring. Necrotizing keratitis is characterized by distorted corneal architecture, substantial stromal inflammatory infiltration, and thinning. In vivo SD-OCT analysis permitted a better understanding of the inflammatory and repair mechanisms occurring in this blinding corneal disease

S-wave π0\pi^0 Production in pp Collision in a Covariant OBE Model

The total cross section for the pp -> pp pi^0 reaction at energies close to threshold is calculated using a covariant one-boson-exchange model, where a boson B created on one of the incoming protons is converted into a neutral pion on the second. The amplitudes for the conversion processes, B N -> N pi^0, are taken to be the sum of s, u and t-channel pole terms. The main contributions to the primary production amplitude is due to an effective isoscalar sigma meson pole in a t-channel, which is enhanced strongly due to offshellness. With this contribution included the model reproduces, both the scale and energy dependence of the cross section.Comment: REVTeX, graphicx, 22 pages (icluding 10 figures