Electrodermal activity (EDA) is an electrical property of the human skin, correlated with person's psychological arousal. Nowadays, different types of EDA measuring devices are used in highly ...versatile fields-from research, health-care and education to entertainment industry. But despite their universal use the quality of their measuring function (their accuracy) is questioned or investigated very seldom. In this paper, we propose a concept of an EDA patient simulator-a device enabling metrological testing of EDA devices by means of a variable resistance. EDA simulator was designed based on a programmable light-controlled resistor with a wide resistance range, capable of simulating skin conductance levels (SCL) and responses (SCR) and was equipped with an artificial hand. The hand included electrically conductive fingers for attachment of EDA device electrodes. A minimal set of tests for evaluating an EDA device was identified, the simulator's functionality discussed and some testing results presented.
When designing a single tube practical acoustic thermometer (PAT), certain considerations should be addressed for optimal performance. This paper is concerned with the main issues involved in ...building a reliable PAT. It has to be emphasised that a PAT measures the ratio of the time delay between the single temperature calibration point (ice point) and any other temperature. Here, we present different models of the speed of sound in tubes, including the effects of real gases and an error analysis of the most accurate model with a Monte Carlo simulation. Additionally, we introduce the problem of acoustic signal overlap and some possible solutions, one of which is acoustic signal cancellation, which aims to eliminate the unwanted parts of an acoustic signal, and another is to optimize the tube length for the parameters of the gas used and specific temperature range.
Virtual Reality (VR) sickness (Cybersickness) is an affliction and a challenge, common to users of virtual environments. We therefore asked ourselves this research question: “Can video content type ...influence users’ VR sickness and physiological response?” We conducted a study with 26 participants, who watched two omnidirectional videos of different content types (neutral and action content) on five distinct video conditions: 2D TV screen, three generations of Oculus Rift VR HMDs (DK1, DK2 and CV1) and on the mobile Samsung GearVR HMD. The Simulator Sickness Questionnaire and the Subjective Units of Distress Scale in combination with the measurement of the physiological parameters (electrodermal activity and skin temperature, respiratory frequency and heart rate) were used to assess the VR sickness effects. The results show that video content type as well as users’ background preferences (preference to adrenaline sports) affected the users’ VR sickness perception. Considering various video conditions, significantly less VR sickness effects were reported with the TV condition than with any VR devices. The results of the subjective questionnaires were correlated with the objective physiological measurements, whereby skin conductance strongly correlated with the VR sickness effects. The effects were also more pronounced in cases of action video content type. Furthermore, we show there is a strong correlation when assessing the VR sickness effects using subjective questionnaire-based methods (the Simulator Sickness Questionnaire and the Subjective Units of Distress Scale) of various complexity, indicating the simple methods (only one question), can effectively be used as well.
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•Confirmed influence of the video content type on the users’ VR sickness response.•Confirmed influence of participants’ background and preferences on the VR sickness response.•VR sickness response assessment by the SSQ, SUDS and physiological response methods.•Evaluation of the experiment procedure (NASA-TLX).
The following paper investigates four novel methods for noncontact measurement of heart rate (HR) and consequently its derivate HR variability, an important marker of autonomic activity proven to be ...predictive of likelihood of future health related events. Feasibility study of basic principles is focused on measurements of signal-to-noise ratio with respect to the distance between the subject and HR sensor/apparatus. The discussed methods are divided into the following 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, whereas the second group consists of measuring devices that use the Doppler effect phenomena (microwave radar, ultrasound radar) and audio signal acquired by a condenser microphone. All measuring devices were assembled and put to test. The results indicate that noncontact measuring of HR is possible, especially for distances of less than 50 cm meeting essential requirements for HR diagnostic purposes.
The object of the proposed paper is to design and analyze the performance of a non-contact heart rate variability (
) measuring device based on ultrasound transducers. The rationale behind ...non-contact
measurement is the goal of obtaining a means of long term monitoring of a patient's heart performance. Due to its complexity as a non-contact measuring device, influential physical quantities, error source and other perturbations were thoroughly investigated. For medical purposes it is of utmost importance to define the target uncertainty of a measuring method from the side of physicians, while it is the role of scientists to realistically evaluate all uncertainty contributions. Within this paper we present a novelty method of non-contact
measurement based on ultrasound transducers operating at two frequencies simultaneously. We report laboratory results and clinical evaluations are given for healthy subjects as well as patients with known heart conditions. Furthermore, laboratory tests were conducted on subjects during a relaxation period, and after 1 min physical activity.
Abstract
This article describes the interlaboratory comparison (ILC) of meteorological and hydrological calibration laboratories in the field of temperature (−30° to 40°C), humidity (10%–95% RH at ...room temperature), and pressure (800–1100 hPa). The ILC was organized by the World Meteorological Organization (WMO) Regional Instrument Centre (RIC) at the Slovenian Environment Agency and University of Ljubljana, Faculty of Electrical Engineering, Laboratory of Metrology and Quality as an accredited interlaboratory comparison (proficiency testing) provider according to the ISO/IEC 17043:2010 standard. The ILC was organized in the target area of WMO Regional Association VI (Europe). The protocol and procedure for ILC were developed within European Metrology Research Project (EMRP) MetoMet2. The participants used their standardized procedures for calibration. Because of the large number of participating laboratories (18) from 17 countries, the ILC was organized in two loops, which were linked via four linking laboratories and evaluated using the En number. The equipment used in both loops exhibited stability and uncertainty, which enabled evaluation of the laboratories’ capabilities. The article presents the data processing, the linkage procedure, and the main results for all three categories (temperature, humidity, and pressure). It was observed that some of the laboratories had unusually low uncertainties. From the metrological point of view, the authors present some comments and suggestions to the laboratories, the results of which differ from the reference ones. The conclusions can help also other meteorological laboratories and organizations that did not participate in the ILC with their everyday work.
•Measuring surface moisture in thin polymers.•NIR laser-based embedded surface moisture meter.•Standard low-cost laser diode system.•In-process measuring of non-milled bulk samples.
In addition to ...bulk moisture, the measurement of moisture profiles is very important in pharmacy, the food, construction and car industries, the military, etc. In special cases, moisture in the upper layers, close to the surface and at the surface, affects various processes more intensively.
Existing measuring principles, such as those based on nuclear magnetic resonance, are unsuitable for particular applications. For this reason, a novel, non-contact, light-reflection type of moisture sensor was designed and investigated (patent pending). It is based on a water molecule's light-absorbing characteristics in the near-infrared (NIR) spectrum. In order to be able to measure the surface and near-surface moisture on a complex geometry with thin walls, the light from a double laser diode is led through an optical fiber and reflected back to an InGaAs photodiode detector. The high stability of the relatively low-cost laser source was achieved through a constant-power laser-control circuit. The sensor's response was measured by a precision embedded data acquisition system NI CompactRIO and evaluated using a moisture analyzer, which measures the bulk moisture with a loss-on-drying technique.
The results prove that it is possible to measure the moisture in polymer layers very close to the surface with an approximately 0.1% effective resolution of bulk moisture content below 2%.
•Skin conductance measurement including information about error and uncertainty.•Calibration by comparison of three commercial skin conductance meters.•Evaluation of electrode displacement impact and ...electrode gel usage.•Model of finger skin conductance profile.•Measurement uncertainty does not meet the target uncertainty.
Electrodermal activity is a frequently measured physiological response in various applications. It is also being increasingly used in clinical applications. Numerous published papers report results of skin conductance measurements in absolute values, but few are concerned with the quality of results. This paper describes a procedure for metrological evaluation of skin conductance measurement. Three commercial devices for measuring skin conductance were calibrated by comparison with a precision digital ohmmeter used as a reference. Combined measurement uncertainty of skin conductance meters was calculated by means of uncertainty of reference instrument and uncertainties due to measurement repeatability, reproducibility, resolution and environmental condition. Additionally, a procedure for evaluation of the effect of electrode displacement and electrode gel was shown. A model of finger skin conductance profile was build. Measurement uncertainty analysis showed that contributions due to resolution and sensitivity of the measuring device, usually obtained from specifications, are negligible when compared to uncertainty of measuring method. Our results indicate that measurement uncertainty does not meet target uncertainty requirements for certain applications.
According to metrological guidelines and specific legal requirements, every smart electronic electricity meter has to be constantly verified after pre-defined regular time intervals. The problem is ...that in most cases these pre-defined time intervals are based on some previous experience or empirical knowledge and rarely on scientifically sound data. Since the verification itself is a costly procedure it would be advantageous to put more effort into defining the required verification periods. Therefore, a fixed verification interval, recommended by various internal documents, standardised evaluation procedures and national legislation, could be technically and scientifically more justified and consequently more appropriate and trustworthy for the end user. This paper describes an experiment to determine the effect of alternating temperature and humidity and constant high current on a smart electronic electricity meter’s measurement accuracy. Based on an analysis of these effects it is proposed that the current fixed verification interval could be revised, taking into account also different climatic influence. The findings of this work could influence a new standardized procedure in respect of a meter’s verification interval.
Merjenje mogočega in nemogočega Geršak, Gregor; Drnovšek, Janko
Elektrotehniski Vestnik,
05/2019, Volume:
86, Issue:
3
Journal Article
Peer reviewed
Povzetek. Danes v velikem obsegu ter pogosto zelo točno merimo pojave in stvari, za katere nekoč ni bilo pričakovati, da bodo v prihodnosti postale merljive. Podobno pa se tudi danes soočamo z zelo ...primerljivo dilemo kot nekoč. To, kar je danes nemerljivo, bo namreč v prihodnosti morda postalo merljivo. In kot je bilo nekoč težko verjeti, da bomo opazovali aktivnost možganov, merili utrip srca na daljavo, merili koncentracije izdihanih plinov, si danes težko predstavljamo, da v prihodnosti ne bi mogli meriti bolečine, strahu, ugodja, zoprnosti, revščine in drugih fizikalnih, psiholoških in socioloških veličin. Na splošno velja, da so merjenja osnova za dobro odločanje. Zato se pri merjenju česarkoli, tudi tistega, kar je danes nemogoče, ne smemo spuščati na področje neeksaktnega in se moramo poskušati čim bolj držati znanstvenih metod in empiričnih dognanj. Merjenje nemogočega je logični nesmisel, ki velja v časovni dimenziji. Na splošno pa se znanost ne sprijazni z dejstvom, da je nekaj, česar nekoč ni bilo mogoče meriti, danes mogoče izmeriti. Prispevek razloži osnovne značilnosti merjenja kot fenomena, kjer s številkami opisujemo lastnosti nekega predmeta ali dogodka, opiše klasično meroslovje in zaključi s predstavitvijo najmlajšega področja merjenj, senzoričnega meroslovja.
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