97 research outputs found
Diseño de un dique flotante de 7.000 toneladas de fuerza ascensional : estudio de la estructura y de los servicios.
Los objetivos principales de este trabajo son, por una parte, diseñar la estructura de un dique flotante, y por otro lado, estudiar y analizar los sistemas y servicios que incorpora el mismo que permiten la realización de todas estas actividades.
Para llevar a cabo el diseño estructural, se efectuarán los distintos avances de la espiral de diseño hasta alcanzar la estructura óptima. El cálculo de los diseños estructurales se realizará mediante un software basado en el método de los elementos finitos, RamSeries 12.0.0
NFC Sensors Based on Energy Harvesting for IoT Applications
The availability of low-cost near-field communication (NFC) devices, the incorporation of NFC readers into most current mobile phones, and the inclusion of energy-harvesting (EH) capabilities in NFC chips make NFC a key technology for the development of green Internet of Things (IoT) applications. In this chapter, an overview of recent advances in the field of battery-less NFC sensors at 13.56Â MHz is provided, and a comparison to other short-range RFID technologies is given. After reviewing power transfer in NFC, recommendations for the practical design of NFC-based sensor tags and NFC readers are made. A list of commercial NFC integrated circuits with energy-harvesting capabilities is also provided. A survey of recent battery-less NFC sensors developed by the group including soil moisture, water content, pH, color, and implanted NFC sensors is done
Implementació d'una estratègia de control de processos en una unitat de fabricació d'envasos plà stics
Els departaments de producció en la industria de productes de gran consum
necessiten reduir els seus costos per continuar sent competitius en el mercat. Les pèrdues
associades a la qualitat del producte, aixà com les mermes que es generen en els processos
de producció d’envasos plà stics, és una de les principals oportunitats per aconseguir aquesta
millora de la competitivitat. L’objectiu d’aquest projecte és implementar una estratègia de
control de processos que ens permeti reduir les fonts de variabilitat en un procés d’extrusió i
bufat d’envasos plà stics, per tal de millorar la qualitat dels productes i l’eficiència del procés
a fi de reduir els costos de producció.
Els passos en els que està estructurat aquest projecte són els següents:
Ø Una anà lisi de la situació actual de l’unitat de fabricació d’envasos plà stics que
s’estudiarà , en el qual es descriu la tecnologia, els materials i els principals punts
del procés de transformació per entendre el marc d’aplicació del projecte.
Ø Una explicació de la metodologia emprada per establir una estratègia de control
de processos pas a pas i la seva implementació a la unitat de fabricació amb
l’anà lisi dels principals problemes que existeixen actualment en aquesta unitat.
Ø Una anà lisi dels principals problemes que existeixen a la unitat de bufat, i
l’elaboració d’un pla d’acció que permeti disminuir les pèrdues de qualitat, reduir
les mermes i millorar l’eficiència del procés de fabricació. En cada cas es fa una
avaluació de les implicacions econòmiques del pla de millora aixà com dels
beneficis obtinguts.
Es conclou que amb la implementació d’aquesta estratègia de control de processos
i la posada en marxa de les millores identificades durant aquest projecte, s’aconsegueix una
millora substancial dels resultats de qualitat, la reducció de mermes del procés productiu i
una millora de l’eficiència i la productivitat del departament. A més, es crea una atmosfera
de millora continua per assegurar la sostenibilitat dels resultats obtinguts
Distortion produced by RF MEMS varactors on digital communication signals
This paper presents a study of the nonlinear effects introduced by MEMS varactors when excited with digitally modulated RF signals (QPSK and 16 QAM). The study is based on simulating a nonlinear model of the MEMS device using harmonic-balance and envelope solvers, and on experimental measurements of the wave reflected by the on-wafer MEMS device. It is shown that the adjacent-channel power ratio (ACPR) and error-vector magnitude (EVM) of the digital signal suffer a degradation due to the device nonlinear distortion.Peer Reviewe
Characterization of dynamics and power handling of RF MEMS using vector measurement techniques
This paper proposes a new method to measure dynamics and power handling of RF microelectromechanical systems (MEMS) devices based on a mobile membrane. The method uses in-phase/quadrature demodulation of an RF signal proportional to the reflection coefficient of the measured device, which contains information of its mechanical properties, such as actuation and release times and instantaneous position of the mobile membrane. Both one-port (capacitors) and two-port devices (switches and extended tuning-range capacitors) can be measured. Its main advantage is the capability of obtaining information from both magnitude and phase variations of the device reflection coefficient to characterize its dynamics and power handling. It is shown that detecting phase is advantageous in high quality factor capacitors, where the magnitude of the reflection coefficient is nearly constant for any position of the mobile membrane. Open-short-load calibration of the system is provided in order to obtain absolute measurements, which are necessary for power-handling characterization. The performances of the proposed method are demonstrated by comparison to systems based on detection of the magnitude of the reflection coefficient. A MEMS capacitor is characterized in terms of dynamics-actuation and release times, and mechanical resonance frequency and in terms of power handling-membrane instantaneous position and phase and tuning range variation.Peer Reviewe
A Passive Harmonic Tag for Humidity Sensing
This paper describes a passive harmonic tag for radio frequency identification (RFID) and wireless sensor applications. The tag uses a dual polarized UHF patch antenna as an input antenna. One of the outputs is connected to a frequency doubler, which consists of a Schottky diode with its output connected to a patch tuned at twice the input frequency. The other output of the input antenna feeds a DC power harvested converter that drives an oscillator which modulates its output signal by controlling the bias point of the Schottky diode. The antenna’s output is also used as a humidity sensor. To achieve this, the antenna is loaded with an interdigital capacitor with humidity-dependent capacitance. The antenna is consequently detuned when humidity varies, and therefore the second harmonic power is received. The tag is manufactured using standard fiberglass substrate. The basic theory of harmonic tag operation is described and compared with the standard backscattering approach. Experimental results with a proof of concept using commercial components are presented
Nonlinear actuation model for lateral electrostatically-actuated DC-contact RF MEMS series switches.
In this work, a nonlinear model to predict actuation characteristics in lateral electrostatically-actuated DC-contact MEMS
switches is proposed. In this case a parallel-plate approximation cannot
be applied. The model is based on the equilibrium equation for an elastic
beam. It is demonstrated that the contribution of fringing fields is
essential. The model relies on finite-difference discretization of the
structures, applying boundary conditions and is solved with a Gauss-
Seidel relaxation iteration scheme. Its usefulness is demonstrated in a series
MEMS switch with lateral interdigital electrostatic actuation.Peer Reviewe
Study of intermodulation in RF MEMS variable capacitors
This paper provides a rigorous study of the causes and physical origins of intermodulation distortion (IMD) in RF microelectromechanical systems (MEMS) capacitors, its analytical dependence on the MEMS device design parameters, and its effects in RF systems. It is shown that not only third-order products exist, but also fifth order and higher. The high-order terms are mainly originated by the nonlinear membrane displacement versus applied voltage and, in the case considered in this study, with an additional contribution from the nonlinear dependence of the reflection coefficient phase on the displacement. It is also shown that the displacement nonlinear behavior also contributes to the total mean position of the membrane. In order to study these effects in depth, an analytical frequency-dependent IMD model for RF MEMS based on a mobile membrane is proposed and particularized to the case of a MEMS varactor-a device for which IMD can be significant. The model is validated, up to the fifth order, theoretically (using harmonic balance) and empirically (the IMD of a MEMS varactor is measured). To this end, a two-tone IMD reflection measurement system for MEMS is proposed.Peer Reviewe
Electrothermally actuated RF MEMS switches suspended on a low-resistivity substrate
This paper presents an electrothermally actuated lateral resistive-contact switch for application to low-gigahertz-band communication systems. It was manufactured on a standard low-resistivity substrate, and its RF performance was improved by suspending the structures 25 μm from the substrate, which is a strategy for future integration with active devices in the system-on-chip concept. Measured insertion losses are−0.26 dB at 1 GHz and −0.65 dB at 6 GHz, return losses are −29 dB at 1 GHz and −25 dB at 6 GHz, and isolations are −52 dB at 1 GHz and −26 dB at 6 GHz. The device is driven by a metal electrothermal actuator, which achieves large displacements and contact forces at much lower temperatures than traditional polysilicon electrothermal actuators. The RF power handling characteristics are also addressed and measured.Peer Reviewe
Tunable dual-band filters based on capacitive-loaded stepped-impedance resonators
This paper proposes the design of tunable dual-band
filters for multi-band multi-standard systems. The main
objective is to provide frequency tunability in the second band
while maintaining the first band fixed. To this end, the
capacitive-loaded stepped-impedance resonator is used. The
work is divided into two main parts. In the first part, a deep
analysis of the capacitive-loaded stepped-impedance resonator
structure is done, which provides analytical closed-form design
equations which eases their design in front of the several
approaches available in the literature up to now. The analysis is
also particularized for the case of the capacitive-loaded uniform
resonator. In the second part, resonators are integrated in two
dual-band tunable filters.Postprint (published version
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