1,187 research outputs found
On the feasibility of noncontact ECG measurements
Get PDF“© © 2017 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.”The article by Kranjec et al. [1], “Novel methods of
noncontact heart rate measurement: A feasibility study” is
interesting and informative as it compares different contactless
methods for heart rate detection. Nevertheless, the use of the
term “capacitively coupled ECG” (CCECG) in the article is
confusing and may mislead readers.
That article studies the feasibility of four noncontact methods
for heart rate measurement, which are classified in
two groups: “the methods measuring electromagnetic energy
generated by the bioelectrical activity within the cardiac
muscle (referred to as direct methods), and the methods
measuring displacement of a part of the subject’s body
caused by the periodic physical contractions of the heart
(referred to as indirect methods). The first group is represented
by a measuring device which detects changes in
surrounding electric field...” [sic]. Later on, this device is
described in [1] as being based on “capacitively coupled electrodes”
and hence termed “CCECG Measuring Device.” The
electrodes are two 48-cm2 metal plates placed side by side
(see [1, Fig. 3]) placed at distances from 5 to 60 cm from the
chest.Peer ReviewedPostprint (author's final draft
El treball de les dones, entre la legalitat i la conveniència (segles XVII i XVIII)
Get PDFEl treball de les dones dins els gremis demostra que les necessitats socials ieconòmiques s’havien avançat a les lleis, fet que va permetre que la integracióde la dona fos possible i necessària, com una activitat important dels gremis tèxtils, com un complement de la feina del marit i com una mà d’obra essencial per a assegurar la continuïtat de l’ofici al llarg dels anys. Les ordinacions d’alguns gremis seders demostren que la vida corporativa havia previst aquesta integració de la dona i contribuïa a la cohesió de la feina i de la societat. Les lleis també concretaven la situació de les dones del gremi, i d’aquelles que, segons les resolucions municipals, podien treballar lliurement, però amb les limitacions que marcaven els privilegis gremials. Es tractava d’una cooperació necessària, només tallada quan apareixien abusos, i llavors, els mecanismes de defensa dels gremis, a través del seu govern, el Consell, pressionaven amb sancions els incomplidors. L’import de les sancions s’aplicava en gran parta ajudar els malalts i els desvalguts de cada gremi i de la ciutatEl trabajo femenino en los gremios demuestra que las necesidades sociales y económicas se adelantaron a las leyes y permitieron que la integración de la mujer no solo fuera posible, sino que se demostró necesaria, con una actividadimportante en los gremios textiles, como complemento del trabajo del marido o formando parte de una mano de obra esencial para mantener la continuidad del oficio a lo largo de los siglos. Las ordenanzas de algunos gremios sederos demuestran que la vida corporativa había previsto esa integración de la mujer, que contribuía a la cohesión social y a la unidad del oficio. Las leyes también concretaban la situación de las mujeres agremiadas y de aquellas que, cumpliendo las resoluciones municipales, podían trabajar por su cuenta en ciertos oficios, pero con las limitaciones que marcaban los privilegios gremiales. Se trataba de una cooperación necesaria, solo interrumpida cuando aparecían abusos, y entonces los mecanismos de defensa de los gremios, a través de su órgano de gobierno, el Consejo, presionaban con sanciones a los incumplidores.El importe de las sanciones se destinaba en gran parte para ayudar a los enfermos y desvalidos de los gremios y de la ciudadFemale labour unions show that social and economic needs came ahead of the law and how the integration of women, especially in the family, was notonly possible but also proved necessary, covering important work with the textile guilds, complementing the work of the husband, and maintaining continuity of trade over the centuries. Analysis of the ordinances, with special attention to that of silk, demonstrates that corporate life had anticipated the integration of women, which contributed to the cohesion and unity needed in the office and society. Laws also established the situation of unionized women, and those that met the municipal resolutions to be able to work at certain trades on their own account, but with the limitations set out by union privileges. This allowed for cooperation only limited in cases of abuse, when the defence mechanisms of the union, through its governing body, the Council, enforced fines on violators, there turn of which was largely devoted to helping the needy of both the unions and the cit
Solar energy radiation measurement with a low–power solar energy harvester
Get PDFSolar energy radiation measurements are essential in precision agriculture and forest monitoring and can be readily performed by attaching commercial pyranometers to autonomous sensor nodes. However this solution significantly increases power consumption up to tens of milliwatts and can cost hundreds of euros. Since many autonomous sensor nodes are supplied from photovoltaic (PV) panels which currents depend on solar irradiance, we propose to double PV panels as solar energy sensors. In this paper, the inherent operation of the low-power solar energy harvester of a sensor node is also used to measure the open circuit voltage and the current at the maximum power point (IMPP), which allows us to determine solar irradiance and compensate for its temperature drift. The power consumption and cost added to the original solar energy harvester are minimal. Experimental results show that the relation between the measured IMPP and solar irradiance is linear for radiation above 50¿W/m2, and the relative uncertainty limit achieved for the slope is ±2.4% due the light spectra variation. The relative uncertainty limit of daily solar insolation is below ±3.6% and is hardly affected by the so called cosine error, i.e. the error caused by reflection and absorption of light in PV panel surface.Peer ReviewedPostprint (author's final draft
Effects of interelectrode capacitance in water conductivity measurements with capacitive electrodes
Get PDFPostprint (author's final draft
The seemingly paradoxical noise behavior of some active circuits
Get PDFThe equivalent input noise for some active circuits does not increase when the signal bandwidth increases or when some of their resistors have a larger value. This seemingly
paradoxical behavior is caused by the different transfer functions for the signal and the respective noise sources associated with these resistors.Peer Reviewe
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