Instrumental Errors Research Articles

Finite element modeling of an origami-inspired delta mechanism with flexible components and joints

Delta mechanism is one of the well-known parallel mechanisms used in robotic applications. In this study, the trajectory behavior of a novel Delta mechanism, which was designed and fabricated using layer-by-layer origami method, is investigated utilizing the finite element method (FEM). The mechanism was modeled with the dimensions of the actual fabricated mechanism. The mechanism consists of four different materials where properties of two materials are extracted experimentally via the tensile testing process. The accuracy of our model was compared to the finite element simulations and the results indicated that the mechanism follows the given trajectory within 0.05 normalized root-mean-square (RMS) error with respect to the kinematic model. The impact of the fabrication and instrumentation errors on the trajectory was further analyzed using FEM simulations and the contribution of each factor on the error was categorized. This validated numerical model can be used in the future to accurately simulate the mechanics of origami-inspired mechanisms and to design new mechanisms.

Improving the accuracy of temperature measurements in heat supply systems

The constant rise in energy prices leads to an increase in the cost of thermal energy, which is used in heat supply systems for industrial and residential premises. Therefore, improving the accuracy of measuring the heat supplied to consumers is an urgent task. Instrumental metering of heat energy requires regular measurement of the temperature of the coolant in the pipelines of the heat supply system. There is an opinion that all the problems of measuring temperature when accounting for thermal energy have been solved. However, this is not the case. The analysis shows that the systematic component of the error in measuring the temperature and the temperature difference between the supply and return pipelines, especially in conditions of small values of the difference, makes a significant contribution to the instrumental error of accounting for thermal energy. The article discusses solutions to minimize these errors in temperature measurement, taking into account the consumption of thermal energy. Keywords: temperature measurements; measurement error; thermal energy; thermodynamics; metrology.

Contributions of internal climate variability in driving global and ocean temperature variations using multi-layer perceptron neural network

Roles of internal climate variabilities regulating global and ocean temperature changes is a hot but complex issue of scientific concern, influencing the comprehensive policy-making in response to global and regional warming. In this study, the time series of monthly global and ocean mean surface temperature (GST and OST, respectively) since 1866 is successfully reconstructed via natural and anthropogenic forcing factors and internal climate variability by using a Multi-Layer Perceptron (MLP) neural network technique. The MLP demonstrates prominent monthly GST and OST reconstruction skills on both interannual and annual time scales. Most of the warming in GST and OST since 1866 is found to be attributable to anthropogenic forcing, while the multidecadal and interannual GST and OST variations are considerably dominated by Atlantic Multidecadal Oscillation (AMO). Internal climate variabilities like Interdecadal Pacific Oscillation (IPO) can amplify the GST and OST changes and explain the global warming slowdown since 1998. Southern Oscillation Index (SOI) performs a similar role as IPO but to a lesser extent. Changes in OST caused by solar forcing are more considerable than those in GST. Moreover, the ‘biased warmth’ during the Second World War is successfully reconstructed in MLP. AMO and IPO can explain most annual and even sub-annual temperature variations during this period, offering an explanation for the existence of this abnormal warm period other than that it was entirely caused by instrumental errors. The generally high accuracy of reconstructions on interannual and annual time scales can enhance the ability to monitor the prompt feedback of specific external radiative forcings and internal variabilities to changes in climate.

Toward Personalized Exercise Medicine: A Cautionary Tale.

This study aimed to examine individual exercise response rates across a range of cardiometabolic variables, cardiorespiratory fitness, and body composition in adults. A retrospective analysis of data from three randomized controlled trials was used in this study. Participants include those who completed the given trial (control, n = 87; intervention, n = 251). Anthropometric (weight, body mass index, waist circumference), cardiorespiratory fitness (V̇O 2peak ), MRI-measured total adipose tissue (AT), abdominal subcutaneous AT, and visceral AT and common cardiometabolic variables were assessed pre- and postintervention using standard methodologies. The technical error (TE), which includes both the day-to-day variability and instrument error, was calculated using pre- and postintervention data from the time-matched control group. On average, all anthropometric, MRI, and V̇O 2peak variables improved significantly after intervention compared with the control group ( P < 0.05). With the exception of glucose disposal rate (37%), after intervention less than 13% of participants improved cardiometabolic outcome measures beyond the day-to-day variability of measurement. In other words, the individual response for 63%-96% of participants fell within the uncertain range (2 TE). Similarly, for absolute V̇O 2peak (L·min -1 ), only 45% of participants improved beyond 2 TE. By comparison, for MRI-derived variables, the majority of participants (77%, 58%, and 51% for total AT, abdominal subcutaneous AT, and visceral AT, respectively) improved beyond 2 TE. The observed reductions beyond 2 TE for WC and body weight were 53% and 63%, respectively. The findings suggest extreme caution when inferring that the cardiometabolic and cardiorespiratory fitness response for a given individual is attributable to the exercise dose prescribed.

The ET mission to search for earth 2.0s

The ET mission to search for earth 2.0s

Research on joint calibration and compensation of the inclinometer installation and instrument errors in the celestial positioning system

AbstractThe application of celestial navigation based on inclinometer to aircraft in near‐earth space and planetary rovers is a significant development direction. Due to the installation and instrument errors of the inclinometer, it is difficult for tilted platforms to obtain high‐precision positioning results. But the installation error of the inclinometer is coupled with the error of the instrument itself, and there is no effective way to measure the two errors separately. To improve the positioning accuracy of the tilted platform, a joint calibration and compensation algorithm of the inclinometer's installation and instrument errors is proposed. First, based on the principle of celestial positioning, the influence analysis model of the inclinometer error on the positioning accuracy is built according to the definition of inclinometer installation error and instrument error, which indicates the traditional algorithms are not suitable for tilted platforms. Then, a joint calibration and compensation algorithm for the inclinometer installation and instrument errors is presented based on coordinate transformation relationship and error propagation characteristics. Finally, a ground test platform is built and the experimental verification of the joint calibration and compensation algorithm of inclinometer error is accomplished. Experiment results show the root mean square errors of the longitude and latitude are and , and the mean distance error is 397.46 m, which is far less than the mean distance error 3629.27 m of the traditional calibration algorithm. It indicates the joint calibration and compensation algorithm can effectively compensate for the errors caused by the inclinometer and obtain higher positioning accuracy.

Mathematical Model and Practical Implementation of Transformer Oil Humidity Sensor

The mathematical dependence of the integral dielectric constant of transformer oil on its humidity is obtained. It is shown that the increase in humidity in the range from 0% to 0.5%, which corresponds to its allowable change, is accompanied by a monotonic increase in the integral dielectric constant along the nonlinear dependence. The design of a high-frequency humidity sensor in the form of a band asymmetric waveguide is proposed, which transforms the latter into a phase shift of the information wave. The mathematical model is developed and the transformation equation is obtained. It has been experimentally established that the total relative error, which consists of the error of this model, the instrumental error of the hard-ware and the subjective error of removing the measured information does not exceed 2%. The article is devoted to solving the problem of reliability of technological equipment and is part of an interdisciplinary study on the development of a set of energy efficient equipment for feed preparation, which is performed on the basis of laboratories of Vinnytsia National Agrarian University.

Modeling and Analysis of Meteorological Contour Matching with Remote Sensor Data for Navigation

This paper outlines the methods, results, and statistical analysis of a model we developed to demonstrate the feasibility of applying remote sensor meteorological data to navigation by using meteorological contour matching (METCOM). Terrain contour matching (TERCOM), a contemporary navigation system, possesses inherent performance flaws that may be resolved and improved by METCOM for subsonic and hypersonic missile or aircraft navigation. Remote sensor imagery data for this model was accessed from the Geostationary Operational Environmental Satellites-R Series operated by the National Oceanic and Atmospheric Administration by using Amazon Web Services through a script we developed in Python. Data processed for the model included imagery data and corresponding geospatial data from the legacy atmospheric profile products: legacy vertical temperature and legacy vertical moisture. Our analysis of the model included an error assessment to determine model accuracy, geostatistical analysis through semivariograms, meteorological signal of model data, and a combinatorial analysis to evaluate navigation performance. We conducted a model assessment which indicated an accuracy of 66.2% in the data used as a combined result of instrument error and interference of cloud formations. Results of the remaining analysis offered methods to evaluate METCOM performance and compare different meteorological data products. These results allowed us to statistically compare METCOM and TERCOM, yielding several indications of improved performance including an increase by a factor of at least 13.5 in data variability and contourability. The analysis we conducted served as a proof of concept to justify further research into the feasibility and application of METCOM.

Research of the regularities of the processes of formation of the surface layer in electric spark alloying

Purpose. Determination of rational parameters of the process of electrospark alloying of 40X steel parts with different types of electrodes. Measurement of the applied layer thickness using the Mora Primus 564 coordinate measuring machine at the customer's plant. To give recommendations on the use of electrospark alloying processing modes in the production process when restoring parts. Research methods are based on effective methods of treatment of metal surfaces and technology of obtaining modified layers by electrospark treatment. Measurements were based on theoretical metrology in modeling instrumental errors of measuring instruments, theoretical principles of instrumentation and mechanical engineering technology. The Mora Primus 564 coordinate measuring machine was used during the measurements. Research results. Electrospark alloying is one of the most common technologies for working with metal, which is characterized by high accuracy and productivity. In addition, high adhesion strength of the applied layer with the base material is provided, and the process itself is easy to perform technological operations and has low energy consumption. The analysis of the main factors influencing the quality of the surface layer during processing is carried out. The process of electrospark alloying of a 40X steel sample was investigated experimentally. During the experiments, modern control and measuring equipment and measurement methods were used. Scientific novelty. For the first time, rational modes of electrospark alloying with vanadium, titanium and tungsten of 40X steel parts have been determined. The dependence of the thickness of the applied layer on the modes of treatment with different electrode material is established. Recommendations for alloying modes in the production process for 40X steel are given. Practical meaning. The experimental researches on electrospark alloying of the 40X steel sample carried out in the production conditions allowed to reveal the basic regularities of the formation of the surface layer and to formulate recommendations for obtaining a coating of a certain thickness. This will restore the worn surface of the part or strengthen the new one.

Problems of spatially distributed quantitative evaluation of soil erosion losses

Formulation of the problem. Water erosion of soils is the most widespread and dangerous soil degradation process in Ukraine. The development of an effective system of soil protection measures requires the use of spatially distributed mathematical models of soil erosion losses. This, in turn, highlights the problem of spatially distributed source data, which adequately reflect the spatial differentiation of factors of the erosion process, among which the main one is the relief. The purpose of the article. Assessing the adequacy of available spatially distributed source data, including cartographic and freely distributed global digital elevation models (DEMs), for spatially distributed quantitative assessment of soil erosion losses at the local level of territorial coverage is the aim of the article. Assessing from this point of view the scale of the original cartographic data, different global DEMs and their spatial resolution, as well as the degree of spatial generalization of the original data. Materials and methods. The solution of the set tasks was performed by the method of simulation modeling with the use of physical-statistical GIS-realized mathematical model of soil erosion-accumulation, developed at Odessa I. I. Mechnikov National University. Source data arrays were tested with DEMs SRTM90 and SRTM30 with a spatial resolution of 3 and 1 angular seconds, respectively, and AW3D30 with a spatial resolution of 1 angular second, as well as with cartographic DEMs based on topographic maps of scale 1:10000 and 1:25000. For testing the initial data, three test plots with an area of 2.67, 0.59 and 0.21 km2 were selected. The plots are located in the Balta district of Odessa region on the southern spurs of the Podolska upland. Results. It is established that freely distributed global digital elevation models SRTM and AW3D30 in the conditions of flat terrain do not always allow to adequately display the structure of slope runoff and, accordingly, to correctly perform calculations of soil erosion losses. The maximum deviation of the average soil erosion losses calculated for the test plots using global DEMs from the soil losses calculated using the reference DEM for SRTM30 and AW3D30 was 27%, for SRTM90 – almost 70%. The distribution of soil losses over the area of test plots obtained using different global DEMs differs even more. When using DEM based on topographic maps, reducing the scale of the original maps from 1: 10000 to 1: 25000 leads to a decrease in the average value of soil erosion losses by about 20% due mainly to reducing the magnitude and area of distribution of maximum soil losses, and on slopes of complex shape also due to changes in the area of accumulation zones. The degree of spatial generalization of the initial data significantly affects the results of the assessment of soil erosion losses both in relation to the average values and their distribution over the area. For small areas, the use of raster cells larger than 50 m is impractical. Scientific novelty and practical significance. It has been shown for the first time that in the conditions of flat terrain at the local level of spatial coverage, the freely distributed global DEM SRTM and AW3D30 are not always hydrologically correct. The reasons and conditions of violation of this correctness are specified. It has been established that the global DEM AW3D30 has local instrumental errors that may make it impossible to use it. The most realistic values of soil erosion losses are provided by DEM SRTM with a spatial resolution of 1 angular second.

Visual and instrumental coverage error of two dental shade guides: an in vivo study

ObjectivesThis study aims to evaluate in vivo the color agreement between natural teeth and dental shade guides by means of visual and instrumental coverage error (mathrm{CE}) index.Materials and methodsThe color of the middle third of 735 incisors was visually determined by two evaluators using the Vita Classical (VC) and Vita 3D Master (V3DM) shade guides. The color match between the natural tooth and the shade tab was rated as poor (P), good (G), or optimum (O) by each observer. CIE color coordinates of the target teeth and shade tabs of VC and V3DM were instrumentally measured using a clinical spectrophotometer. Visual ({mathrm{CE}}_{mathrm{V}}) and instrumental ({mathrm{CE}}_{mathrm{I}}) coverage error indexes were computed using CIELAB and CIEDE2000 metrics for both shade guides. For {mathrm{CE}}_{mathrm{V}} calculation, only the concordant inter-observer determination on tooth shade rated as O–O or O–G was used. The results were evaluated using perceptibility (PT, {mathrm{Delta E}}_{mathrm{ab}}^{*}= 1.2, {mathrm{Delta E}}_{00}= 0.8) and acceptability (AT, {mathrm{Delta E}}_{mathrm{ab}}^{*}= 2.7, {mathrm{Delta E}}_{00}= 1.8) color thresholds for dentistry.ResultsVC and V3DM exhibited {mathrm{CE}}_{mathrm{I}} (2.5, 3.2, and 3.2, 2.7 CIELAB units; 1.9, 2.3, and 2.8, 2.4 CIEDE2000 units, respectively, for O–O and O–G match) and {mathrm{CE}}_{mathrm{V}} (4.7, 4.8, and 4.1, 4.6 CIELAB units; 3.3, 3.4, and 3.4, 3.6 CIEDE2000 units, respectively, for O–O and O–G match) values greater than 50:50% AT for both color difference formulas. {mathrm{CE}}_{mathrm{I}} contributes more than 50% (53.2–82.4% range) to the {mathrm{CE}}_{mathrm{V}} value. This contribution depends on the shade guide used and the quality of the visual rating.ConclusionsThe evaluated shade guides exhibited visual coverage errors above acceptability thresholds, largely due to the contribution of the instrumental coverage error to the visual coverage error.Clinical relevanceIt necessary to further improve commercially available dental shade guides to facilitate achievement of satisfactory esthetics results in clinical practice.

ON THE DEVELOPMENT OF THE ALGORITHM FOR DETERMINATION OF STADIA CONSTANT OF ELECTRONIC TACHOMETERS

An algorithm for determining the stadia constant of the rangefinder is developed and tested. This algorithm is based on the generalized reduced gradient (GRG) method with consistent use of criteria of minimizing the maximum deviation and minimizing the total sum of squares of deviations. There were some stages of the research. First, we carried out 200 measurements with equal accuracy by a SOUTH NTS-350 electronic tachometer. The statistical processing of measurement results enabled specification of the optimal number of measurements for the device taking into account the dependence of the correlation values of instrumental and random errors. Having determined the optimal number of measurements, we continued the study of the proposed method of calculating the stadia constant of electronic tachometers. According to the data obtained during the measurement of the range of the target, which consisted of four points, conditional equations were compiled. These conditional equations are based on the relationships between the length of the measured target and its segments in all combinations, taking into account the stadia constant of the rangefinder. Due to the large number of measurements, the solution of such system of equations is to find the minimum of some function for determining the errors of the measured distances. Our methodology is based on the use of the Lagrange multiplier method in finding the solution of a nonlinear programming problem, which in most software resources is called the Nonlinear Generalized Consolidated Gradient (GRG). The essence of this solution is to find a conditional local extremum. In this case, it is most appropriate to consistently use the criteria of minimizing the maximum deviation and minimizing the total sum of squares of deviations. The method of minimizing the maximum deviation makes it possible to reject gross errors in the measured values. The following minimization of the total sum of squares of deviations will allow to minimize random errors of the measured distances, as the selected samples are subject to the normal distribution law. Thus, the most probable value of the constant correction of the rangefinder and lengths of the measured target and its segments for all possible combinations has been obtained.

Algorithm for determining satellite orientation based on use of earth sensor and magnetometer

An algorithm for determining the orientation of a satellite based on information from an Earth sensor and a magnetometer is considered. The effect of instrumental errors of the magnetometer on the accuracy of orientation determination is analyzed. The TRIAD algorithm is compared with an algorithm in which only the heading angle is calculated.

Experimental strapdown inertial navigation system for the autonomous guidance system of a short-range uav

The task of experimental verification of the possibility of using a miniature strapdown inertial navigation system (SINS) on micromechanical sensors for autonomous guidance of a short-range manned aircraft moving along a programmed hypothetical trajectory is considered.&#x0D; A mathematical model of the first approximation of the instrumental errors of the two-coordinate autonomous SINS of the aircraft with a short flight time was obtained. The mathematical model allows both to calculate the values of these errors for specific types of inertial sensors used in SINS (direct analysis problem), and to choose the types of accelerometers and gyroscopes based on ensuring the given accuracy of SINS (inverse synthesis problem). The requirements for permissible errors of accelerometers and gyroscopes of the SINS sensor unit have been determined.&#x0D; The design and manufacturing technology of an experimental SINS based on a triaxial micromechanical accelerometer and three uniaxial micromechanical gyroscopes are described.&#x0D; The technology of flight tests of the experimental SINS is considered. The test results of the experimental SINS of the aircraft, created in accordance with the requirements specified in the article, confirmed the correctness of the chosen approach to ensuring the accuracy of the SINS for the autonomous inertial guidance system of short-range aircraft.

Multifrequency array calibration in presence of radio frequency interferences

Radio interferometers are phased arrays producing high-resolution images from the covariance matrix of measurements. Calibration of such instruments is necessary and is a critical task. This is how the estimation of instrumental errors is usually done thanks to the knowledge of referenced celestial sources. However, the use of high sensitive antennas in modern radio interferometers (LOFAR, SKA) brings a new challenge in radio astronomy because they are more sensitive to Radio Frequency Interferences (RFI). The presence of RFI during the calibration process generally induces biases in state-of-the-art solutions. The purpose of this paper is to propose an alternative to alleviate the effects of RFI. For that, we first propose a model to take into account the presence of RFI in the data across multiple frequency channels thanks to a low-rank structured noise. We then achieve maximum likelihood estimation of the calibration parameters with a Space Alternating Generalized Expectation-Maximization (SAGE) algorithm for which we derive originally two sets of complete data allowing closed-form expressions for the updates. Numerical simulations show a significant gain in performance for RFI corrupted data in comparison with some more classical methods.

INSTRUMENTAL ERRORS OF TRANSMISSION LINE PARAMETERS METER

The article is devoted to the construction of the instrumental errors dependences of the transmission line parameters meter on the parameters of the physical or structural hardware components of the meter. For this, when constructing a mathematical model, only the main functional connections between the structural links of the measuring device were selected, neglecting the influence of external factors on the stability of the structural elements parameters. As is know, each measuring instrument must have a certain set of metrological characteristics. According to these characteristics, measuring instruments are selected for use in certain technological processes, and it is they that determine the reliability of the data obtained as a result of measurements. These characteristics include a list of physical quantities that can be measured, the conditions under which the measurement process can be carried out, metrological (informational) reliability, accuracy class or permissible errors of the measuring instrument itself. The conditions under which the measuring instruments can be used depend on the constructive and technological implementation of the device, since the measurement technique and its implementation in the electrical circuit are not accompanied by special requirements for the operation of the device. This means that such a meter can be produced with a focus on laboratory use, for use in a mobile version and in the field, for use in complex electronic systems as an element of built-in control, etc. All this follows from the given measurement technique and analysis of the synthesized meter circuit. The exact characteristics of a measuring instrument include two important components: method errors and instrumental errors. To build such dependencies on the parameters of physical or structural hardware components and the values of the measured quantities, it is necessary to build a mathematical model of the measuring equipment. It is advisable to restrict ourselves to the construction of a mathematical model, which will take into account the dominant factors of the accuracy characteristics that cause first-order errors. Such a model, depending on the needs that arise during the operation of the measuring instrument, can be supplemented by certain sources of influences, certain causal actions that will cause the appearance of errors of the second and even third order. These are errors caused by changes in temperature, humidity, atmospheric pressure, mechanical vibrations, electromagnetic and acoustic fields, etc.

An insight into tetracycline photocatalytic degradation by MOFs using the artificial intelligence technique

Tetracyclines (TCs) have been extensively used for humans and animal diseases treatment and livestock growth promotion. The consumption of such antibiotics has been ever-growing nowadays due to various bacterial infections and other pathologic conditions, resulting in more discharge into the aquatic environments. This brings threats to ecosystems and human bodies. Up to now, several attempts have been made to reduce TC amounts in the wastewater, among which photocatalysis, an advanced oxidation process, is known as an eco-friendly and efficient technology. In this regard, metal organic frameworks (MOFs) have been known as the promising materials as photocatalysts. Thus, studying TC photocatalytic degradation by MOFs would help scientists and engineers optimize the process in terms of effective parameters. Nevertheless, the costly and time-consuming experimental methods, having instrumental errors, encouraged the authors to use the computational method for a more comprehensive assessment. In doing so, a wide-ranging databank including 374 experimental data points was gathered from the literature. A powerful machine learning method of Gaussian process regression (GPR) model with four kernel functions was proposed to estimate the TC degradation in terms of MOFs features (surface area and pore volume) and operational parameters (illumination time, catalyst dosage, TC concentration, pH). The GPR models performed quite well, among which GPR-Matern model shows the most accurate performance with R2, MRE, MSE, RMSE, and STD of 0.981, 12.29, 18.03, 4.25, and 3.33, respectively. In addition, an analysis of sensitivity was carried out to assess the effect of the inputs on the TC photodegradation by MOFs. It revealed that the illumination time and the surface area play a significant role in the decomposition activity.

Intraoperative Transcranial Electrical Motor Evoked Potential (TceMEP) as a Therapeutic Tool in Spine Surgery: A Case Series Report

ABSTRACT We report two cases of unilateral loss of TceMEP secondary to spinal instrumentation errors and the subsequent recovery of TceMEP responses following prompt intervention. During the period of TceMEP loss, there were no concomitant SSEP changes beyond the threshold criteria. Postoperative physical examination revealed normal strength and motion in the affected extremities in both patients. These cases illustrate that in addition to being a reliable intraoperative diagnostic tool, TceMEP monitoring displays therapeutic usefulness in appraising corrective actions to the existential risk of neurological injuries.

Ionospheric total electron content (TEC) above Ecuador

The equatorial ionosphere over the Ecuadorian territory has not been previously studied, although there are some studies in other equatorial geographical positions, local research is required to characterize the ionospheric magnetoactive plasma in this region.In this study, for the first time in Ecuador, using pseudophase and pseudorange data from the satellite signals of the GPS system, detected at the Riobamba-Ecuador (RIOP) station, the Total Electronic Content (TEC) is estimated in the period between the years 1999 and 2019. The TEC values and their daily, weekly, monthly and annual variation are calculated and compared with the observed data of the IGS network (International GNSS Service). The fit of the observed series with the series of the dispersive model has a goodness of fit of 0.88, which is quite acceptable. The adjustment can be improved by incorporating data from new local stations, as well as instrumental errors and delays and in the received signals, all of which were not considered in the present work.

814 Devices measuring transepidermal water loss of the skin: a systematic review of measurement properties

IntroductionTEWL is a physiological property of skin which increases when the epidermis is damaged. It is, therefore, a commonly utilised measure of skin barrier integrity. Devices measuring TEWL are available as open, semi-open or closed chamber. Studies of reliability examine the consistency of measurement, and/or responsive whereas measurement error scores in absolute terms the amount of error due to sources of variation.MethodsThe search strategy aimed to locate published and unpublished studies. Databases searched included PubMed, Embase, CINAHL and Web of Science, utilising identified keywords and limited to studies in English. Grey literature sources were searched to identify any unpublished documents. Study selection using the inclusion criteria was then assessed by two reviewers for methodological quality utilising the COSMIN risk of bias tool to assess the reliability and measurement error of outcome measurement instruments.Studies examining the reliability and/or measurement error of TEWL measurement devices were included. Studies that only report on measurement of TEWL outcomes without examination of reliability and/or measurement error were excluded.ResultsA total of 22 devices were examined in the 38 included studies. The quality of study design was on average rated as ‘Adequate’ however reliability and measurement error statistical methods were on average rated as ‘Doubtful’.ConclusionsTEWL measurement devices were found to demonstrate good reliability and often correlated with other devices. However, measurement error was highly variable but improves under in-vitro conditions.