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The durability issue is the primary factor affecting the life and cost of Polymer Electrolyte Membrane Fuel Cell (PEMFC). This paper presents a novel State of health (SOH) prognosis method for PEMFC in different conditions using Principal Component Analysis (PCA) and Gaussian Process Regression (GPR). Firstly, the robust locally weighted smoothing method is used to preprocess the recorded PEMFC operation data for filtering measurement errors. Then, PCA is applied to extract the principal components of the time series of original multi-dimensional input variables for PEMFC, eliminating the correlation between the original variables and reducing the dimensionality of input variables. Finally, the degradation prognosis and Remaining Useful Life (RUL) prognosis are made by GPR. Two degradation experiments for PEMFC verify the proposed method in different conditions. The test result shows that PCA can effectively reduce the dimensionality of PEMFC operating conditions. Compared with traditional methods, PCA-GPR has higher SOH prognosis accuracy. PCA-GPR provides a 462-h RUL prognosis on a life duration of 1150 h, which is sufficient for maintaining the PEMFC. • PEMFC operating variables are reconstructed by the principal component analysis. • PEMFC degradation prognosis model is established by Gaussian process regression. • The proposed method provides a higher degradation prognosis accuracy for PEMFC. • Proposed method makes a long remaining useful life prognosis for PEMFC. [ABSTRACT FROM AUTHOR]

Global, 24/7, and all-weather Synthetic Aperture Radars (SARs) are optimal platforms for Ground Moving Target Indication (GMTI) missions, and the tether constraint provides a stable mechanic connection for such configurations. To fulfill the requirements of such missions, the Space Tether System (STS) must be deployed to horizontal positions to form the necessary along-track interference baseline, which is unstable relative to traditional vertical positions and has not received adequate focus. To deal with this problem, this study focuses on the deployment control of the STS to the unstable horizontal positions. Firstly, the properties of the STS at the horizontal position are analyzed, and a synthetic criterion of measurement error is defined based on the observation principle of the GMTI mission. Secondly, two deployment control strategies are proposed, and corresponding desired trajectories are generated by considering two occasions respectively. In the end, considering the instability of horizontal positions, an adaptive closed-loop controller is designed utilizing the backstepping method to address gravitational moment and other disturbances. Simulations demonstrate that the system can successfully attain the desired horizontal positions under both deployment strategies, and the designed controller can quickly track trajectories under initial state errors and external disturbances. • Two along-track deployment strategies are proposed for unstable horizontal positions. • A synthetic criterion of measurement error is defined to evaluate deployment accuracy. • A back-stepping adaptive controller is designed to suppress unstable tether oscillations. [ABSTRACT FROM AUTHOR]

A series of Y 2 MoO 6 :0.01Er3+/0.09 Yb3+ upconversion phosphors doped with different concentrations of Li + ions (0.05, 0.10, 0.15, 0.20, 0.25, and 0.30 mol) were prepared by the high temperature solid phase reaction method, and their physical phase structures and upconversion luminescence were analyzed. At the excitation wavelength of 980 nm, the addition of Li+ sharply increased the upconversion luminescence intensity. With the increase of Li+ ion content, the luminescence intensity first increases and then decreases. When the doping amount reaches 0.25 mol, the luminescence intensity reaches the maximum, and the sample emits green light in the two-photon process. Y 2 MoO 6 :0.01Er3+/0.09 Yb3+/0.25Li + exhibits excellent temperature sensing properties. Its absolute sensitivity S a reaches up to 0.012 K-1, the relative sensitivity S r is 0.017 K-1 and the measurement error δ T is less than 0.3 K at room temperature. Its temperature sensing performance is far superior to similar materials. In addition, Judd-Ofelt theory calculations revealed that in comparison with Y 2 MoO 6 :0.01Er3+/0.09 Yb3+, its Ω 2 increased from 0.56 × 10−20 cm2 to 3.68 × 10−20 cm2, and the spectroscopic quality factor Ω 4 /Ω 6 ratio reached 4.09, which is much higher than that of the other fluorescent materials. The main reason is that Li + replaces the Y3+ ion lattice site, causing lattice distortion and reducing the lattice symmetry around the active ion. The increase in asymmetry increases the possibility of spontaneous radiative transitions. It is shown that the prepared upconversion luminescent materials have potential applications in the field of solid-state lasers and optical sensing. [ABSTRACT FROM AUTHOR]

In order to achieve rapid and precise measurement of distance between two pins of flexspline in harmonic reducers, an rapid non-contact measurement strategy based on standard/actual parts comparison is proposed. Firstly, to eliminate the installation eccentricity error of flexspline fixture, a sine-quadrant eccentricity error elimination method is designed. The sinusoidal curve and quadrant of the measured fixture eccentricity error with respect to the fixture rotation angle is used to calculate the eccentric error components along x and y axes, which has the advantages of simplicity and rapidity. Secondly, a Gaussian-Harmonic Wavelet Filtering (GHWF) algorithm is proposed to filter out the noise in the measurement process, which can effectively suppress the Gibbs phenomenon in harmonic wavelet transformation and improve the signal-to-noise ratio. Finally, an experimental platform including baseplate, turntable, flexspline, moving platform and laser sensor is constructed, in order to verify the performances of error elimination, noise filtering and distance measuring. Experimental results show that the measurement error of the proposed strategy is less than 7 μm, which is consistent with the accuracy obtained by the commercial high-precision gear measuring instrument. The average measurement time is about 29.6 s, much less than the 5 min of the commercial instrument, showing great application potential for the efficient distance measurement of gears and flexsplines. • A rapid non-contact measurement strategy for distance between two pins of flexspline in harmonic reducers. • To address the eccentricity issue in fixture installation, a sine-quadrant eccentricity error elimination method is proposed. • A Gaussian-Harmonic Wavelet Filtering algorithm combining harmonic wavelet with Gaussian function is proposed. • Various experiments and verifications. [ABSTRACT FROM AUTHOR]

Detailed measurement of the curved surface of an industrial product with a radius of curvature of less than a few millimeters is a challenging task for tactile coordinate measuring machines. To estimate a surface profile, tip radius correction is typically performed by estimating the tip correction vector direction. However, a substantial measurement error is introduced by the error in estimating the tip correction vector direction under measurement conditions such as a large position measurement error of an indicated measured point or a short sampling interval, In this study, a method that can estimate a surface profile by calculating the envelope of a probe tip path was proposed. The proposed method was experimentally and numerically confirmed to be able to estimate surface profiles with sub-micrometer accuracy under such measurement conditions. • A novel method was developed for determining the profile of a surface with a curvature of less than few millimeters using a tactile coordinate measuring machine. • We verified the feasibility of using the proposed method that calculates the envelope of the probe tip path. • The surface profile obtained by the proposed method can be estimated with sub-micrometer accuracy. [ABSTRACT FROM AUTHOR]

In this paper, the topography of 6082 aluminium alloy specimens after fatigue bending tests was studied with a comprehensive evaluation of measurement noise caused by vibration. Roughness results were acquired by contactless Focus Variation Microscopy (FVM). Studied data were pre-processed, removing the non-measured points and outliers with regular methods, respectively, and high-frequency noise was considered. The variations in ISO 25178 roughness parameters were studied. Based on the previous studies, it was found that surfaces after fatigue bending tests can be difficult to consider when analyzing the measurement noise in a selected bandwidth. Some advantages of profile data extraction in selected directions, like horizontal, vertical or crack, were found deficient, even in studies by various functions, like autocorrelation, power spectral density, or texture direction ratio. When noise suppression methods depend on the details studied, boundary areas were extracted to compare and highlight the presence of high-frequency data characteristics. The proposed method was validated when contrasting standardised Gaussian or median filtering techniques with the spline filtering approach. A proper filter for the reduction of vibrational noise from the results of FVM topography measurements was suggested based on the proposed procedure. Finally, it was proposed how use the new method for reducing errors caused by high-frequency measurement noise in the surface topography of specimens after fatigue bending tests. • The surfaces of 6082 aluminium alloy specimens after fatigue tests were characterised. • The surface topography was measured by the focus variation microscopy (FVM) technique. • High-frequency noise removal methods were supported by specified profile data extraction. • The improvement in measurement noise reduction was received by boundary areas studies. • The accuracy of the ISO 25178 parameter analysis can be improved by the proposed method. [ABSTRACT FROM AUTHOR]

The celestial navigation system based on star angle (SA) is a classical autonomous navigation method for the spacecraft, which directly provides the position information of the spacecraft relative to the near celestial body. But due to the relativistic effects, the star direction observed by spacecraft is inconsistent with that acquired from star ephemeris, which reduces navigation accuracy of SA. In addition, SA cannot directly provide the velocity information of the spacecraft. StarNAV is a novel celestial navigation method that utilizes the relativistic effects, which mostly provides the velocity information of the spacecraft. In this paper, the star angle modified with relativistic effects (SAMRE)/StarNAV integrated navigation method is proposed. The measurement model of SAMRE is established by considering relativistic effects in the measurement model of SA. Simulation results indicate that during the Mars approach phase, SAMRE has better navigation accuracy compared with SA, and the navigation accuracy of the SAMRE/StarNAV integrated navigation method is higher than that of SAMRE, StarNAV and SA/StarNAV, respectively. Furthermore, the paper analyses the impact of measurement errors on the navigation accuracy of SAMRE/StarNAV. [ABSTRACT FROM AUTHOR]

Hip migration percentage (MP) measured on anteroposterior pelvis radiographs is the gold standard to assess the severity of hip displacement in children with cerebral palsy (CP). Repeated exposure of these children to ionizing radiation under a hip surveillance program is undesirable. Recently, a semi-automatic approach to measure MP US on ultrasound (US) images was validated in a phantom study. This pilot in vivo study applied the previous phantom method and aimed to determine the reliability and accuracy of the MP US. Thirty-four children (23 boys and 11 girls) aged 8.9 ± 3.1 y old and diagnosed with CP were recruited. A total of 59 hips were scanned once, while 43 of these were scanned twice to evaluate the test-retest reliability. Two raters (R1 and R2) manually measured MP US ; procedures included selecting images of interest, cropping a region of interest and removing soft tissues on hip US images. Custom software was developed to measure MP automatically after the manual pre-image processing. The intra-class correlation coefficients (ICC 2,1) for the test-retest (R1), intra-rater (R1) and inter-rater (R1 vs R2) reliabilities were 0.90, 0.94 and 0.82, respectively. The standard error of measurement of MP US for all three evaluations was ≤3.0%. The mean absolute difference between MP US and MP X-ray and the percentage of MP US within clinical acceptance error of 10% for R1 and R2 were (R1: 6.2% ± 4.9%, 84.7%) and (R2: 7.6% ± 6.1%, 73.7%), respectively. This study demonstrated that US scans were repeatable and MP US could be measured reliably and accurately. [ABSTRACT FROM AUTHOR]

An important aspect to consider in the evaluation of parts and assemblies by X-ray computed tomography (XCT) is the attenuation coefficient of the different materials involved, which are directly related to their density; depending on this coefficient, the X-ray penetration varies and, therefore, varies the contrast between different materials and with the background. This becomes more critical in those assemblies in which materials are characterized by a high difference in density, where the lighter material could be difficult to be characterised. In this paper, the effect of the presence of metals in the dimensional evaluation of polymeric geometries (having lower density than the metal parts) is studied, to evaluate the errors caused in dimensional measurements of different geometries and surface texture characterization. Based on a common geometry, four scenarios have been experimentally tested with variations of metal amount, in which macro geometries (precision spheres made by different polymers) and micro geometries (inclined ramps manufactured by fused deposition modelling (FDM)) have been characterised. Results show errors in the surface determination of the polymeric features directly related to the presence of metal: a high amount of steel makes significantly difficult to accurately determine the interface between background and material due to the noise and artifacts created, while aluminium has less influence on the irregularities of the features extracted. This effect is more evident for polymers with lower density due to the higher difference. Numerically, most affected parameters are those sensible to variations in surface determination, such as spheres' form error and ramps' maximum surface texture (Sz), while more solid features as spheres' diameters, distances and ramps' average surface texture (Sa and Sq) remain more stable. In conclusion and to sum up, it has been found that the quantity of metal present in assemblies made of polymeric and metallic materials is correlated with distortions in the dimensional evaluation of polymeric features by XCT. [ABSTRACT FROM AUTHOR]

A rigid-flexible dual-arm space robot offers promising potential for on-orbit operation due to complementary strengths of its rigid and flexible manipulators. The rigid manipulator has the advantage of large payload capacity and high motion accuracy. The segmented linkage flexible manipulator is ideal for maneuvering in narrow, unstructured environments like internal satellite inspections and maintenance, due to its flexibility and slender body. However, there are inevitable tracking errors due to the multiple cable-driven mechanisms in the flexible manipulator. It's difficult to get the configuration and end pose of flexible manipulator without adding external sensors. To address these issues, this paper presents a method for configuration reconstruction and all-joint synchronous measurement of the flexible manipulator. The flexible manipulator is captured by the stereovision system mounted on the rigid manipulator. The links' equivalent center points are recognized by central moment method and edge line extraction method based on the natural characteristics. Joint - to - link kinematic model of flexible manipulator is established to measure joint angles and reconstruct configuration. Several simulations and experiments are carried out to validate the proposed method. The experimental results showed links' average measurement position errors were less than 13 mm and joint angles reconstructed using the proposed method had an error of approximately 0.35 °. These results demonstrate the accuracy and robustness of the proposed method. [ABSTRACT FROM AUTHOR]

• A phase error correction method (IFOA-JMEC) for InIRA images is proposed. • Ionospheric scintillation and atmospheric turbulence are main errors source for InIRA. • Correcting spatial-variant Error in range by dividing subblocks and interpolating. • Background atmosphere has little influence on InIRA height measurement accuracy. • Phase screen models for ionospheric scintillation and atmospheric turbulence. The interferometric imaging radar altimeter (InIRA) is a newly developed microwave remote sensing system in recent years. It is of great significance to analyze the main sources of its height measurement error through simulation, and to develop the corresponding image phase error correction methods. This can provide basis and reference for the subsequent correction of the real images phase error. In this study, according to the interaction principle between atmospheric interference and InIRA radar electromagnetic waves, the influence of background ionosphere and background troposphere on height measurement error is analyzed by introducing ionosphere and troposphere delays into echo signals respectively. The impact of ionospheric scintillation and atmospheric turbulence on the height measurement error is analyzed by building multi-layer phase screen models. Then according to the analysis results, a phase error correction method for InIRA images combined by the improved fruit fly optimization algorithm (IFOA) and the joint minimum entropy criterion (JMEC) is proposed. The image is divided into several sub-images with negligible spatial variation of phase error according to the principle of first range and then azimuth. IFOA is used to search the optimal phase compensation values iteratively to compensate the phase of all sub-images. When the joint entropy of the sub-images reaches the minimum value, the phase error correction of the whole InIRA image is completed. Experimental results show that the proposed method can correct the phase of InIRA images with inconspicuous features and polluted by weak ionospheric scintillation and atmospheric turbulence relatively quickly. After correction, the height measurement error can be reduced from decimeter level to centimeter level. The correction accuracy and efficiency of the proposed method are superior to those of the method combined by particle swarm optimization algorithm and joint minimum entropy criterion (PSO-JMEC), the method combined by genetic algorithm and joint minimum entropy criterion (GA-JMEC), the method combined by phase gradient autofocus and Map Drift (PGA-MD), and improved PGA-MD algorithm. [ABSTRACT FROM AUTHOR]

The characteristics of additively manufactured parts (topological optimisation, freedom of design ...) present a challenge from a metrological point of view. In this respect, non-contact inspection is of great importance for the rapid verification of this type of parts. However, their particular characteristics (stair-effect, high roughness, surface finish) can contribute to measurement errors and deviations when using different optical inspection equipment. In relation to this, 3D scanning point-clouds filtering can improve the results by increasing precision during inspection. In particular, this paper evaluates the influence of applying filters to digitize additive manufactured metal parts, which are scanned using different optical inspection systems commonly used in industry (based on laser triangulation, conoscopic holography and structured light techniques). The main objective is to establish the most suitable inspection procedure depending on the inspection system used. According to the dimensional results achieved, it can be concluded that the filtering does not have significant influence, regardless of the used sensor. However, the geometrical results are strongly influenced by the point-cloud quality; consequently, it is recommended to apply filters for most of the evaluated optical systems. One of the main contributions of this study is the definition of the filtering process methodology prior to non-contact inspection, depending on both the used optical system and the part to be evaluated, in order to define the most suitable filtering parameter to achieve a precise optical inspection. • Effect of sigma filter on optical inspection of additively manufactured metal parts • Point cloud filtering does not influence dimensional results, only geometric ones • Different industrial optical sensors require filtering for accuracy geometric inspection • Applying 3σ/2σ filter allows to achieve geometric results similar to contact values • 1σ filter (more restrictive) distorts values, resulting in form error below reference [ABSTRACT FROM AUTHOR]

Thermal error significantly influences the accuracy of precision computer numerical control (CNC) machine tools. The key to compensating thermal error lies in selecting appropriate temperature measurement points and establishing an accurate error prediction model. Traditional methods separate measurement points selection and prediction modeling, that is, selecting temperature measurement points first and then establishing the prediction model using these points. These methods are difficult to achieve optimal matching between measurement points and the prediction model, resulting in shortcomings in modeling accuracy. To address these challenges, an integrated optimization method for measurement points layout and error modeling for digital twin of CNC machine tools is proposed. A dual-stage attention-based long short-term memory combined with convolutional neural network (DA-CLSTM) error modeling method is proposed to accurately predict the thermal error for different numbers of temperature measurement points. Then, an integrated method of virtual-real temperature measurement points layout and error modeling is proposed, which ensures the temperature measurement points and the error prediction model are closely matched, offering rational sensors layout and high-accuracy prediction. Finally, experiments are conducted on the spindle system test bench to validate the method proposed in this research. Through integrated optimization of measurement points layout and the prediction model, the proposed method achieves high-accuracy thermal error prediction across various sensor counts and maintains reliable prediction ability when the number of sensors is reduced. This method is applied to a digital twin system of MKL7150 grinding machine, and effectively improves the accuracy of actual machining. • An integrated optimization method for measurement points layout and error modeling of CNC machine tools is proposed. • A dual-stage attention-based long short-term memory combined with convolutional neural network model is designed. • Genetic algorithm is used to optimize the layout of measurement points to achieve the optimal prediction effect. • The proposed method achieves high prediction accuracy and maintains accuracy well with fewer sensors. • The method is validated on the test bench and embedded into the digital twin system to achieve thermal error prediction. [ABSTRACT FROM AUTHOR]

Quantitative research on vigour as a therapeutically responsive marker of positive mental health, has become possible by virtue of the validation of the Vigour Assessment Scale (VAS). Considering that its validation and therapeutic responsiveness were examined in an avolitional schizophrenia population, using the VAS outside these constraints requires that its psychometric properties be investigated in a more general non-clinical population. Social media respondents (n = 787) were recruited on social media through snowball sampling and data were obtained for statistical analyses through an online questionnaire comprising the VAS and measures of work-place vigour, active involvement in personal growth, behavioural activation, procrastination, and fatigue. Convergent validity was confirmed in moderate to strong positive correlations between the VAS and measures approximate to vigour including physical strength (r = 0.805), cognitive liveliness (r = 0.676), planfulness (r = 0.61), and intentional behaviour (r = 0.595). Discriminant validity was evident in negative correlations with procrastination (r = −0.593) and fatigue (r = −0.786). The VAS showed good internal consistency (Cronbach α = 0.951), split-half reliability (r = 0.892), test-retest reliability (r = 0.861), and a low standard error of measurement of 3.73 within a theoretical range of 82 points. Exploratory factor analysis yielded a clear two-factor structure. Results are limited to willing participants who responded through social media. Vigour may now be measured clinically as an indication of positive mental health and well-being. It may also be further investigated for its relations to other parameters of health, personality, and the efficacy of professional and self-enhancing interventions that aim for the cultivation of vigour. • Vigour correlated positively with strengths, liveliness, and intentional behaviour. • Vigour correlated negatively with procrastination and fatigue. • The Vigour Assessment Scale measured validly, reliably, and with small error. • Vigour may be measured clinically as an indication of positive mental health. • Vigour may be researched in relation to well-being, personality, and interventions. [ABSTRACT FROM AUTHOR]

The use of computed tomography (CT) for craniofacial measurements is common in medical imaging, but concerns about accuracy and reliability persist, especially with different CT technologies. This study assessed the accuracy of twenty-six common measurements on consecutive CT images from the same patients, using multidetector CT (MDCT) and cone-beam CT (CBCT) with two software programs (Amira and Dolphin). Ten adult subjects with consecutive CBCT scans within one year were randomly selected. Another ten subjects with consecutive MDCT scans were paired with the CBCT group based on age, gender, race, occlusion, and craniofacial pattern. All digital imaging and communications in medicine (DICOM) files were randomly coded and analyzed using the two software programs. Intra-examiner reliability was assessed using the intraclass correlation coefficient. Successive measurement errors from consecutive scans for both imaging modalities and software programs were compared. For most skeletal linear and angular measurements, Dolphin showed greater successive measurement errors compared to Amira. Eight of the 26 common measurements had errors greater than one unit (millimeter or degree). Despite almost perfect intra-examiner reliability for upper airway analysis, average successive measurement errors were notably high, particularly for intraoral and oropharyngeal airway volumes. The successive Dolphin measurement error for oropharyngeal airway volume on CBCT images was over three times that on MDCT images. Given the substantial successive measurement errors observed during consecutive CT scanning for the upper airway, this study does not support the quantitative use of CT for analyzing changes in airway dimensions for research purposes. [ABSTRACT FROM AUTHOR]

Missing data occurs frequently in sample surveys. Numerous imputation techniques have been proposed to tackle the problem of missing data, and, in fact, limited works are available in the literature to deal with the issue of missingness while the data are ridden with measurement errors (ME). In addition, no work has been done on the robustness to handle the issue of missing data when it is contaminated with correlated measurement errors (CME). This article proposes some robust imputation methods (RIM) to impute the missing data in the presence of CME. The mean square error (MSE) of the proposed RIM is derived from the first-order approximation and examined with the MSE of the conventional imputation methods. The results are theoretically established and explained using a vast simulation study. Two applications of real data sets are presented to illustrate the efficiency and superiority of the suggested estimators relative to some estimators considered in this study. [ABSTRACT FROM AUTHOR]

• Ceiling effects in therapeutic benefit are commonly understood to impact cystic fibrosis. • Day-to-day variation in measured FEV 1 is common. • Floor and ceiling effects can be exaggerated in the presence of measurement error. • Estimation of ceiling effects should account for biasing effects of measurement error. Clinical trials often demonstrate treatment efficacy through change in forced expiratory volume in one second (FEV 1), comparing single FEV 1 measurements from post- versus pre-treatment timepoints. Day-to-day variation in measured FEV 1 is common for reasons such as diurnal variation and intermittent health changes, relative to a stable, monthly average. This variation can alter estimation of associations between change in FEV 1 and baseline in predictable ways, through a phenomenon called regression to the mean. We quantify and explain day-to-day variation in percent-predicted FEV 1 (ppFEV 1) from 4 previous trials, and we present a statistical, data-driven explanation for potential bias in ceiling and floor effects due to commonly observed amounts of variation. We recommend accounting for variation when assessing associations between baseline value and change in CF outcomes in single-arm trials, and we consider possible impact of variation on conventional standards for study eligibility. [ABSTRACT FROM AUTHOR]

Intraoperative stem anteversion, which is the angle between the lower leg axis and the trial-stem axis with hip flexion and adduction, is generally evaluated by the surgeon's visual estimation during total hip arthroplasty (THA). However, the conventional approach can be influenced by knee osteoarthritis or uncertain surgeon's observation point. Therefore, we developed a new method for measuring the stem anteversion angle in the neutral hip position using an original rod attached to the trial-stem perpendicular to the long axis and parallel to the stem neck. This study aimed to assess the accuracy of our method in comparison with the conventional method of measuring intraoperative stem anteversion angle. We measured the intraoperative stem anteversion angle in consecutive 106 hips of 106 patients who underwent cementless primary THA with a tapered wedge stem. Absolute error in the stem anteversion angle was expressed as the difference between intraoperative (common vs. neutral hip positions) and postoperative computed tomography measurements, i.e., true stem anteversion. Additionally, we investigated the factors affecting these errors. The absolute error of measurement was significantly smaller in the neutral hip position than in the common position (3.0° ± 2.5° vs. 8.0° ± 3.9°; p < 0.0001). The factor associated with the error was advanced knee osteoarthritis in the common position, whereas it was not statistically significant in the neutral hip position. This study suggests that the error in the intraoperative measurement of stem anteversion is decreased by measuring in the neutral hip position during THA. [ABSTRACT FROM AUTHOR]

The usage of liquefied hydrogen (LH 2) is growing fast as the EU aims to be climate-neutral by 2050. Therefore, reliable and consistent measurements of LH 2 amounts (as determined by flow meters) will become increasingly important for custody transfers. Reliability and consistency of measurements is established from calibration. Due to the lack of facilities being able to calibrate flow meters directly with LH 2 as calibration fluid, the question arises whether the measurement error of the calibration performed on a different fluid and different process conditions are representative for the errors when measuring LH 2. An on-site calibration of two turbine meters measuring LH 2 flow was performed. A Coriolis mass flow meter calibrated on water was used as a reference in conjunction with a dedicated flow meter model, which was validated by a directly SI-traceable calibration on liquefied natural gas. LH 2 flow rates were within 1000 kg/h and 3000 kg/h, which are relevant to hydrogen transport by LH 2 trailers. The analysis of the measurement data reveal errors on totalized mass ranging from 2.0 % to 2.9 % with a total calibration uncertainty of 1.3 % (k = 2), where the main uncertainty source was identified as the on-site density estimate necessary to convert the volume flow measurements into mass flow measurements. The results indicate the need for reliable and accurate temperature measurements (the latter allowing for an accurate density estimate), so that volume based and mass based amount measurements can be compared with smaller uncertainties. • Reliable measurements of liquefied hydrogen amounts will be crucial for custody transfer. • Direct calibration of flow meters on liquefied hydrogen is currently not possible. • Novel results of liquefied hydrogen flow measurement of an on-site calibration are presented. • The analysis reveals errors between 2.0 % and 2.9 % with an uncertainty of 1.3 % (coverage factor = 2). • The main uncertainty source was identified as the on-site density estimate. [ABSTRACT FROM AUTHOR]

In this paper, an assessment of a topography measurement method for fracture surfaces of 10HNAP steel after bending-torsion fatigue tests was performed. Surface roughness was measured by using a non-contact Focus Variation Microscopy (FVM) technique in which the non-measured points (NMPs) and outliers (spikes) were removed by the application of general methods. The results revealed, that the optical measurement method introduced variations in the high-frequency errors, considered as noise within the selected bandwidth. Therefore, the minimization of the high-frequency noise (HFN) was proposed based on an extensive examination of ISO 25178 roughness parameters. Additionally, a general S -filter was applied, as recommended by international standards and commercial software. It was used to identify and remove noise from the measured data after pre-processing. Consequently, levelling and eliminating of NMPs and spikes was successfully performed. Subsequently, the results obtained by using various filters were compared to further assess the impact of different filtration bandwidths. Finally, the proposed procedure was validated by implementing different general functions, such as autocorrelation (ACF), power spectral densities (PSD), and texture direction (TD). It was concluded, that coupled characteristics, including profile and areal measurements, should be studied simultaneously since they are necessary to analyze the fracture surfaces comprehensively. • Fatigue fracture surfaces were characterized after bending, torsion and bending-torsion. • Surface topography measurements were performed by using the FVM technique. • Approaches for noise compensation measurement and error data analysis were presented. • The error reduction was applied after the ACF, PSD, TD and thresholding operations. • The accuracy of ISO 25178 roughness parameter evaluation was validated and improved. [ABSTRACT FROM AUTHOR]

This paper presents a cost-effective and efficient closed-loop calibration method to enhance the absolute positioning accuracy of industrial robots. The method utilizes an economical and highly accurate set of simple measurement devices, including a device mounted on the robot's end effector and a spherical constraint device positioned within the robot's workspace. A novel local area measurement method is employed for the spherical constraint device, effectively converting position errors into the errors in the sphere center position of the constraint device. Furthermore, the error model considers both kinematic parameter deviations of the robot itself as well as those of the measurement device, along with non-kinematic errors caused by link self-weight. The closed-loop calibration model relies on position constraints, enabling identification and compensation of all error parameters using Levenberg Marquardt method after substituting measured data. The effectiveness of this proposed method is demonstrated through simulation and experimentation. In simulations, average position error reduces from 8.249 mm to 0.8384 mm, while absolute mean difference in sphere center positions obtained using our measurement equipment decreases from 1.206 mm to 0.1027 mm. Significant reductions in both position error and difference in sphere center position are indicated after calibration. This proves that the absolute mean value of the sphere center position difference can be used as the basis for judging the size of the robot's end position error. Experimental results show that absolute mean difference in sphere center position decreases from 0.4319 mm to 0.02869 mm, leading to substantial improvement in overall positioning accuracy. • Calibration model incorporates both kinematic and non-kinematic deviation. • Local area measurement data effectively reflects the robot's end position error. • Closed-loop calibration method exhibits robustness in the presence of noise. [ABSTRACT FROM AUTHOR]

Further acceleration of DWI in diagnostic radiology is desired but challenging mainly due to low SNR in high b-value images and associated bias in quantitative ADC values. Deep learning-based reconstruction and denoising may provide a solution to address this challenge. The effects of SNR reduction on ADC bias and variability were investigated using a commercial diffusion phantom and numerical simulations. In the phantom, performance of different reconstruction methods, including conventional parallel (SENSE) imaging, compressed sensing (C-SENSE), and compressed SENSE acceleration with an artificial intelligence deep learning-based technique (C-SENSE AI), was compared at different acceleration factors and flip angles using ROI-based analysis. ADC bias was assessed by Lin's Concordance correlation coefficient (CCC) followed by bootstrapping to calculate confidence intervals (CI). ADC random measurement error (RME) was assessed by the mean coefficient of variation (CV ¯) and non-parametric statistical tests. The simulations predicted increasingly negative bias and loss of precision towards lower SNR. These effects were confirmed in phantom measurements of increasing acceleration, for which CCC decreased from 0.947 to 0.279 and CV ¯ increased from 0.043 to 0.439, and of decreasing flip angle, for which CCC decreased from 0.990 to 0.063 and CV ¯ increased from 0.037 to 0.508. At high acceleration and low flip angle, C-SENSE AI reconstruction yielded best denoised ADC maps. For the lowest investigated flip angle, CCC = {0.630, 0.771 and 0.987} and CV ¯ ={0.508, 0.426 and 0.254} were obtained for {SENSE, C-SENSE, C-SENSE AI}, the improvement by C-SENSE AI being significant as compared to the other methods (CV: p = 0.033 for C-SENSE AI vs. C-SENSE and p < 0.001 for C-SENSE AI vs. SENSE; CCC: non-overlapping CI between reconstruction methods). For the highest investigated acceleration factor, CCC = {0.479,0.926,0.960} and CV ¯ ={0.519,0.119,0.118} were found, confirming the reduction of bias and RME by C-SENSE AI as compared to C-SENSE (by trend) and to SENSE (CV: p < 0.001; CCC: non-overlapping CI). ADC bias and random measurement error in DWI at low SNR, typically associated with scan acceleration, can be effectively reduced by deep-learning based C-SENSE AI reconstruction. [ABSTRACT FROM AUTHOR]

Pediatric sleep-disordered breathing is associated with multiple health problems. Polysomnography is the reference standard for identifying this disorder, but availability is limited. Therefore, an alternative screening tool is needed. Globally, the Sleep-Related Breathing Disorder scale of the Pediatric Sleep Questionnaire (PSQ) has proven to be a feasible tool. Consequently, this study aimed to translate and culturally adapt the PSQ into Dutch and then to examine the cultural validity, internal consistency, and test-retest reliability of the Dutch version among a general population visiting oral healthcare centers. The translation, review, adaptation, pretest, and documentation approach was used to ensure cross-cultural adaptation of the PSQ. Then, 220 children (2.4–18 years) were sampled for clinimetric evaluation. We estimated the cross-cultural validity by comparing the factor analyses of the original PSQ and the Dutch version. Reliability was assessed using Cronbach's alpha, Spearman's correlation, the intraclass correlation coefficient, the standard error of measurement, and a Bland-Altman plot. The factor loading patterns of the Dutch version matched with the original study around the four predetermined factors: breathing, sleepiness, behavior, and other. The internal consistency, with a Cronbach's α of 0.77, was acceptable. The test-retest reliability with an intraclass correlation coefficient and Spearman's correlation of 0.89 and 0.93, respectively, was good to excellent. Cultural adaptation was ensured and the results support cross-cultural validity, internal consistency, and test-retest reliability of the Dutch Sleep-Related Breathing Disorder scale of the PSQ. This questionnaire could therefore be a valuable tool for screening disordered breathing in Dutch children. • TRAPD approach ensured cross-cultural adaptation of the Dutch-SRBD from the original PSQ (Chervin et al). • The Dutch-SRBD exhibited good psychometric properties, demonstrating cross-cultural validity and reliability. • The Dutch-SRBD supports screening in general populations, aiding referral decisions for sleep-disordered breathing in children. [ABSTRACT FROM AUTHOR]

Structured light systems (SLSs) are commonly used for precision dimensional measurements. These are active systems in that the projected structured light pattern is used to establish correspondence between the projector and the camera(s) to provide more accurate 3D reconstruction as opposed to passive camera-based systems that rely on the user or features in images to identify corresponding points between the cameras. Errors in the calibration of the model parameters of an SLS can lead to systematic errors in dimensional measurements. In this paper, we explore the topic of performance testing of an SLS, specifically, the sensitivity of the length tests described in the VDI/VDE 2634-2 guideline and the ISO 10360-13 standard to the model parameters (such as intrinsic parameters of the camera and the projector, and camera-projector geometry parameters) of an SLS. The results are based on a hybrid approach of simulations performed using data obtained experimentally from an SLS mounted on a Cartesian coordinate measuring machine (CMM) which is used primarily to position the target at different points within the measurement volume. The results show that the length tests described in the ISO 10360-13 standard provide better sensitivity to the model parameters than the VDI/VDE 2634-2 guideline. However, even the ISO 10360-13 length tests do not detect all parameters with high sensitivity. A model-based approach in identifying length tests (i.e., the position and orientation of reference lengths) such as described in this paper provides better sensitivity to model parameters and therefore is more likely to detect systematic errors in SLSs. • Built a structured light system on a CMM and determined the length errors between points in a rectangular grid. • Assessed the sensitivity of lines defined in the VDI/VDE 2634-2 and ISO 10360-13 documents to systematic errors in SLSs. • Identified position/orientation of lines in the measurement volume that provides maximum sensitivity to systematic errors. • Demonstrated the superiority of our sensitivity analysis-based approach in detecting SLS systematic errors. [ABSTRACT FROM AUTHOR]

This paper presents a new methodology for the measurement of thermal errors of Swiss-type lathes. The basis of the proposed method is the torque limit skip function integrated in the lathe's control which stops the motion of a linear axis if the torque on the corresponding axis servo is exceeded. The skip signal is triggered via a slow contact between a bar in the lathe's spindle and an artefact in the lathe's tool holder. Experimental results indicate that when a sufficiently low torque override limit is applied, the axis positioning repeatability under the repeated application of the torque limit skip is within ± 1 μ m. The relative change in position of the axis after the skip measured over several hours is the thermal error which can be compensated. The proposed measurement technique offers significant advantages over conventional thermal error measurement with a touch-trigger probe or linear displacement sensors: if available on the machine's control, it does not require any specialized installation, can be used during production, and delivers comparable results without high additional equipment costs. • Thermal errors of precision machine tools are measured with the torque limit skip. • Torque limit skip function replaces touch-trigger/displacement probe measurement. • Swiss-type lathe is compensated with the ARX thermal compensation model. • Thermal errors are significantly reduced with torque limit skip based compensation. [ABSTRACT FROM AUTHOR]

This paper outlines the evaluation methodology for a Telescopic Simultaneous Ballbar (TSB) developed for distance measurement using an interferometer as a reference equipment. The procedure is executed in a 3-axis machine tool, one of the final applications of the TSB that is machine tool volumetric verification. Two distinct evaluation techniques are devised, with the new virtual line approach enabling an assessment of the TSB's performance within an extended verification volume and requiring only a single alignment position for the interferometer. The measurement repeatability of the equipment is assessed and its measurement uncertainty is estimated in workshop conditions. The results reveal the flexibility of the TSB measurement process similar to that of a laser tracker and the degree of measurement accuracy, which shows values comparable to the interferometer. Consequently, the TSB could facilitate faster and more accurate machine tool verification and calibration compared to existing systems. • Method for evaluating a Telescopic Simultaneous Ballbar using an interferometer is proposed. • Simultaneous operation of three interferometric lines for machine tool volumetric verification. • The virtual lines enable TSB verification in a wider MT volume using single alignment positions. • Standard deviation of the TSB distance measurement error is below 0.6 μm. • TSB measurement uncertainty in workshop conditions shows values below 1.3 μm. [ABSTRACT FROM AUTHOR]

The paper presents a case study of the data analysis in the CDHS scattering experiment of particle physics performed in 1983. The case study compares the function of computer simulation in the data analysis with recent philosophical work on the role of simulations in high energy physics (HEP) and the theory-ladenness of the data. In the data analysis of CDHS, computer simulations entered an iterative process of probabilistic data correction. The computer simulation was a crucial ingredient of the data analysis that served to increase the accuracy of the measurement. The way in which simulation was used corresponds in a certain sense to the function of "models as mediators" (Morgan and Morrison), by mediating knowledge about measurement errors and the way of correcting them. I argue that this use of simulation did not give rise to a vicious circle of adjusting data to theory and vice versa but only to a weak, or benign, theory-ladenness of the data compatible with scientific realism. In the publication of the CDHS results, the measurement outcomes are called "observed data", indicating a realist attitude of the physicists towards the measured quantities which does not exactly fit in with entity realism or theory realism. [ABSTRACT FROM AUTHOR]

Ankle muscle strength should be assessed after a lateral ankle sprain (LAS) because a strength deficit can lead to chronic ankle instability (CAI). No field method is available to obtain quantitative ankle dynamic strength values. This study aimed to assess the reliability of the one-repetition maximal (1-RM) method and to compare ankle muscle strength between healthy volunteers and those with CAI using 1-RM strength assessment approach. We recruited 31 healthy volunteers and 32 with CAI. Dorsiflexor, evertor, and invertor 1-RM were performed twice at a one-week interval. The intraclass correlation coefficient (ICC) and minimal detectable change (MDC) were calculated. Strength values were compared between healthy volunteers and CAI. The 1-RM method is reliable for assessing ankle dorsiflexor, evertor, and invertor strength, with an ICC ranging from 0.76 to 0.88, and MDC ranging from 19 to 31%. Volunteers with CAI obtained evertor (3.0 vs. 3.5 N/kg), invertor (2.9 vs. 3.7 N/kg), and dorsiflexor (5.9 vs. 6.5 N/kg) strength values that were lower than healthy volunteers (p < 0.05). The 1-RM test can be used in practice to assess evertor, invertor, and dorsiflexor strength during the rehabilitation of LAS. This field method could help practitioners to detect a strength deficit and individualize a strengthening programme if necessary. • This is the first study to measure ankle muscles strength with the 1-RM approach. • One-RM is a reliable method to assess evertor, invertor, and dorsiflexor strengths. • Ankle strength is significantly lower in population with chronic ankle instability. • The 1-RM method provides an field alternative for assessing dynamic ankle strength. • One-RM strength values can guide rehabilitation after lateral ankle sprain. [ABSTRACT FROM AUTHOR]

Diffusion tensor imaging (DTI) is a promising technique for the visualization of the cervical spinal cord (CSC) in vivo. It provides information about the tissue structure of axonal white matter, and it is thought to be more sensitive than other MR imaging techniques for the evaluation of damage to tracts in the spinal cord. The purpose of this study was to determine the within-participants reliability and error magnitude of measurements of DTI metrics in healthy human CSC. A total of twenty healthy controls (10 male, mean age: 33.9 ± 3.5 years, 10 females, mean age: 47.5 ± 14.4 years), with no family history of any neurological disorders or a contraindication to MRI scanning were recruited over a period of two months. Each participant was scanned twice with an MRI 3 T scanner using standard DTI sequences. Spinal Cord Toolbox (SCT) software was used for image post-processing. Data were first corrected for motion artefact, then segmented, registered to a template, and then the DTI metrics were computed. The within-participants coefficients of variation (CV%), the single and average within-participants intraclass correlation coefficients (ICC) and Bland-Altman plots for WM, VC, DC and LC fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) were determined for the cervical spinal cord (between the 2nd and 5th cervical vertebrae). DTI metrics showed poor to excellent within-participants reliability for both single and average ICC and moderate to high reproducibility for CV%, all variation dependent on the location of the ROI. The BA plots showed good within-participants agreement between the scan-rescan values. Results from this reliability study demonstrate that clinical trials using the DTI technique are feasible and that DTI, in particular regions of the cord is suitable for use for the monitoring of degenerative WM changes. • DTI measures reveals poor and excellent within-participants reliability, depending on the ROI. • Within-participants variability of DTI metrics are generally acceptable <20% showing moderate to high reproducibility. • Using an automated segmentation software such as SCT is useful and provides atlas-based information. [ABSTRACT FROM AUTHOR]

• Comparison of foot insole impressions using the Reel measurement methodology. • Measurements to the first and fourth toes were least variable. • Measurements from the heel to the third and fifth toes were most variable. • Foot insole impressions were assessed by experienced and inexperienced analysts. • The measurements of experienced analysts were more precise. In forensic podiatry, footprints have been shown to provide a valuable source of discriminatory information. Footprints may be found in various forms, such as bare footprints, sock-clad footprints, or as impressions on insoles within footwear. This study utilized quantitative measures of foot impressions on pairs of insoles from shoes worn by the same person from a population of 31 adults. The measurements were determined by using the Reel method and comprised measurements from the heel to the tips of the toes and width of the ball. The purpose of the study was to assess the margin of error for these measurements to determine whether they were sufficiently accurate for forensic use. A secondary purpose of this study was to determine whether the analyst's experience or lack thereof in forensic podiatry had an impact on the precision of measurement data. The insole foot impressions were assessed by two podiatrists with forensic podiatry experience in footprint analysis, footprint research, and in using the Reel method of footprint measurement, as well as by three students of podiatric medicine without any such experience. A statistical analysis of the data from the study was performed using SPSS v28 (IBM SPSS Statistics for Windows, Version 28.0. Armonk, NY: IBM Corp). The most reliable measurements were of forefoot width, heel to first toe, heel to second toe, and heel to fourth toe. The greatest variation occurred in the measurements of the heel to the third and fifth toes. The measurements of the forensic podiatrist analysts showed less variability than those of the podiatry students, suggesting that measurement precision is related to the experience of the analyst. [ABSTRACT FROM AUTHOR]

The influence of substrate effects on the accurate measurement of mechanical properties of thin films remains to be clarified. Therefore, in this study, (AlCrNbSiTi)N thin films were deposited on four substrates—Si, SiO 2 , sapphire (Al 2 O 3), and Ni—with varying thicknesses. Nanoindentation testing was conducted to measure the mechanical properties, revealing variations in the modulus of the thin film depending on the substrate and film thickness. To address these variations, we introduced the concept of two springs connected in series, following Hooke's law, to determine the elastic deformations of the thin film and its underlying substrate. By applying linear regression to four datasets corresponding to equivalent film thicknesses but different substrates, substrate-induced measurement errors were effectively mitigated, and the true modulus of the thin film was determined. Furthermore, we introduced a k value to represent the ratio of the actual force on the substrate to the force exerted by the indenter. Our findings indicate that even when the indenter contact depth is less than 1% of the film thickness, the substrate is still subjected to 7.6% of the applied force. This underscores the non-negligible nature of substrate elastic deformation during the measurement process and importance of correcting for substrate-induced variations in thin-film moduli. The findings can contribute to advancing the understanding of mechanical properties in ceramics and related materials. [ABSTRACT FROM AUTHOR]

We aimed to assess the reliability of quantifying psoas major (PM) and quadratus lumborum (QL) stiffness with ultrasound shear wave elastography (SWE), and to explore the effects of gender and physical activity on muscle stiffness. Fifty-two healthy participants (18–32 y) were recruited. To determine reliability, 29 of them underwent repeated SWE measurements of PM and QL stiffness by an operator on the same day. The intra-class correlation coefficients (ICC 3,1), standard error of measurement (SEM) and minimal detectable change with 95% confidence interval (MDC 95) were calculated. The rest participants underwent a single measurement. Two-way MANCOVA was conducted for the effects of gender and physical activity on muscle stiffness. The observed reliability for PM (ICC 3,1 = 0.89–0.92) and QL (ICC 3,1 = 0.79–0.82) were good-to-excellent and good, respectively. The SEM (kPa) was 0.79–1.03 and 1.23–1.28, and the MDC 95 (kPa) was 2.20–2.85 and 3.41–3.56 for PM and QL, respectively. After BMI adjustment, both gender (PM: F = 10.15, p = 0.003; QL: F = 18.07, p < 0.001) and activity level (PM: F = 5.90, p = 0.005; QL: F = 6.33, p = 0.004) influenced muscle stiffness. The female and inactive groups exhibited higher stiffness in both muscles. SWE is reliable for quantifying the stiffness of PM and QL. Female and physical inactivity may elevate PM and QL stiffness, underscoring the importance of accounting for these factors in muscle stiffness investigations. Larger prospective studies are needed to further elucidate their effects. [ABSTRACT FROM AUTHOR]

Pen-on-paper pain drawing are an easily administered self-reported measure that enables patients to report the spatial distribution of their pain. The digitalization of pain drawings has facilitated the extraction of quantitative metrics, such as pain extent and location. This study aimed to assess the reliability of pen-on-paper pain drawing analysis conducted by an automated pain-spot recognition algorithm using various scanning procedures. One hundred pain drawings, completed by patients experiencing somatic pain, were repeatedly scanned using diverse technologies and devices. Seven datasets were created, enabling reliability assessments including inter-device, inter-scanner, inter-mobile, inter-software, intra- and inter-operator. Subsequently, the automated pain-spot recognition algorithm estimated pain extent and location values for each digitized pain drawing. The relative reliability of pain extent analysis was determined using the intraclass correlation coefficient, while absolute reliability was evaluated through the standard error of measurement and minimum detectable change. The reliability of pain location analysis was computed using the Jaccard similarity index. The reliability analysis of pain extent consistently yielded intraclass correlation coefficient values above 0.90 for all scanning procedures, with standard error of measurement ranging from 0.03% to 0.13% and minimum detectable change from 0.08% to 0.38%. The mean Jaccard index scores across all dataset comparisons exceeded 0.90. The analysis of pen-on-paper pain drawings demonstrated excellent reliability, suggesting that the automated pain-spot recognition algorithm is unaffected by scanning procedures. These findings support the algorithm's applicability in both research and clinical practice. [ABSTRACT FROM AUTHOR]

Patient-reported outcome measures (PROMs) may have an important role in screening and monitoring for unpleasant symptoms in kidney failure. However, there is still little evidence on the psychometric properties of the measures available to assess physical and psychological symptoms in people on hemodialysis. This gap makes it difficult to decide which measure is the most appropriate for use in clinical practice and research with this population. This systematic review aimed to critically appraise, compare, and summarize the quality of the measurement properties of PROMs used to assess symptoms in adults on hemodialysis. The protocol for this review was registered in PROSPERO (CRD42023393441). The last database search update was performed on November 25, 2022. The COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN) guidelines informed methodological quality assessment, data extraction, analysis, and synthesis. Twenty-seven primary studies reported the measurement properties of 16 PROMs used to assess physical and psychological symptoms in adults on hemodialysis. Results showed that most measures lacked the necessary psychometric evidence to attest their suitability for this study population, and few underwent rigorous validation procedures. Overall, caveats were found on methodological quality and evidence of content validity and structural validity, and little data was available on responsiveness, measurement error, and cross-cultural validity. The current systematic review provides the basis for identifying PROMs with potential utility for assessing symptoms in hemodialysis care. Several recommendations are presented to help guide future research aimed at improving the rigor of validation and/or translation procedures of existing (and future) measures using COSMIN guidelines. [ABSTRACT FROM AUTHOR]

The Perceived Stress Scale (PSS) is a widely recognized patient-reported outcome measure designed to assess an individual's level of perceived stress. The PSS consists of ten items, with six items phrased negatively and four phrased positively. Most studies have found that the PSS consists of two dimensions, with negative and positive items forming separate dimensions. However, some studies suggest a one-dimensional construct. We aimed to investigate the dimensionality of the PSS and the impact of wording effects on the measurement properties of the scale. We tested a modified version of the PSS (mPSS), with negative wording of all items. In a Danish sample, respondents were randomized to answer the PSS or the mPSS. We used confirmative factor analysis and Rasch analysis to assess the validity and reliability of the two versions. The proportion of person misfit was also evaluated. A total of 326 respondents completed the PSS, whereas 306 completed the mPSS. For the PSS, a two-factor model fitted the data best, and the first positively formulated item showed under-discrimination (Rasch model item fit rejected). The mPSS had higher measurement precision than the PSS, but evidence of local dependence was seen for both versions. Fewer respondents gave improbable responses to the mPSS compared to the PSS. Data comes from three different respondent samples. The PSS was deemed essentially unidimensional, with the extra variance being attributed to the reversed items. To reduce response bias, clinicians and researchers may apply the mPSS. • This study compared the properties of the Perceived Stress Scale with a modified version that worded all items negatively. • The Perceived Stress Scale was found to be essentially unidimensional. • The modified version displayed lower measurement error than the Perceived Stress Scale in the upper end of the stress scale. • A lower proportion of respondents gave improbable responses to the modified version compared to the Perceived Stress Scale. [ABSTRACT FROM AUTHOR]

The Ice, Cloud, and Land Elevation Satellite-2 (ICESat-2) mission, operated by NASA, was launched in September 2018. The mission aims to obtain height measurements that create a global portrait of Earth's radial dimension, gathering data to monitor changes of terrain including glaciers, sea ice, forests and more. It is important to understand the error budget of the observations, one component of which is radial orbit error. Apart from the altimetric ranging errors, radial orbit errors directly influence the accuracy of the measurement of sea surface height (SSH). These errors can be assessed by analyzing the difference of SSHs at ground track intersections, so-called crossover differences (XO differences). An effective approach is to model the orbit error by minimizing the residual XO difference by the least-squares method. XO differences are assumed to be caused by the difference of radial orbit errors between ascending and descending arcs, the sea surface variation, mispointing, and measurement errors. Since the sea surface variation in a short time interval and measurement errors can be considered as random variable, these residuals can be reduced by the method of XO adjustment. In our study, the RMS XO differences of ICESat-2 is significantly reduced from 17.2 cm to 8.7 cm in the Arctic region. [ABSTRACT FROM AUTHOR]

The purposes of this study were to preliminarily report patient-identified change for the neck disability index (NDI) as either important or not important with time between follow-up of approximately 7 to 10 days and assess the credibility of the preliminary results with the use of a recently established credibility instrument. This study was a secondary analysis from a primary randomized clinical trial assessing short-term physical therapist care for individuals with mechanical neck pain. Neck disability index scores and participant-reported importance of global rating of change scores from 42 participants were analyzed from a randomized clinical trial assessing short-term responses to thoracic manipulation and dry needling for neck pain. Patient-important change was computed using receiver operating characteristic curves, and statistical error of the measurement was calculated using (SD × [1 − r]1/2) × 1.96 to assess measurement error at the 95% CI. Thirty-six participants rated global rating of change as important, and 6 rated it as not important. Patient-important change was calculated at 3.5 NDI points on a 0 to 50 NDI scoring scale. This value exceeded the statistical error, which was calculated at 2.16 NDI points. The credibility analysis revealed that 4 of 5 criteria showed strong credibility for the patient-important change estimate. Using patient-determined importance to dichotomize improvement may yield a lower threshold than current researcher-defined methods. Clinically, these results may be more responsive to patient-centric change than using previously reported minimal clinically important difference data. [ABSTRACT FROM AUTHOR]

Range of motion (ROM) is an outcome measure commonly used when treating acute and chronic hand injuries and conditions. Increased adoption of telehealth service provision in hand therapy practice, influenced by the advent of COVID-19, has led to the need for a valid and reliable approach to measure the range of motion of the digits of the hand when providing hand therapy services using telehealth. To determine if performing manual goniometry during a livestream teleconsultation is reliable and clinically useful to measure the range of motion of the fifth digit when providing hand therapy services using telehealth. Clinical measurement, repeated-measures study. According to a measurement protocol, 12 independent raters (who currently provide hand therapy services) each obtained several screen-based goniometric range of motion measurements of the fifth digit at 2-time points. Raters were surveyed on the clinical utility of the telehealth-based goniometry approach. Measures of relative and absolute reliability were calculated to evaluate test-retest and inter-rater reliability. Free-text responses were analyzed using content analysis. Inter-rater reliability was excellent for all flexion and extension measures (intraclass correlation coefficient [ICC] ≥ 0.89) but poor for the arc of motion (ICC ≤ 0.67). Test-retest reliability was poor (ICC ≤ 0.43). No statistically significant differences between test and retest measurements were observed (P ≥ 0.24). The overall coefficient of variation indicated good precision (14.69%). Measurement error (≤6.07º) and limits of agreement (≤6.33) had acceptable levels to support clinical use. Content analysis revealed several practical considerations. This study suggests that performing manual goniometry during a livestream teleconsultation is unreliable for measuring the range of motion of the fifth digit. However, when combined with patient-reported and functional outcomes, this approach may be suitable to facilitate a range of motion assessment for certain functions of telehealth service provision in hand therapy practice. • A telehealth-based goniometry approach facilitates virtual hand therapy assessment. • This method has acceptable measurement error (<5º) but poor test-retest reliability. • Inter-rater reliability varies among 12 hand therapy clinicians (ICC, 0.98–0.19). • Telehealth use in hand therapy has decreased following the height of COVID-19. • Comparison with a valid reference standard is recommended for future research. [ABSTRACT FROM AUTHOR]

• Mueller polarimetry develops latent fingerprints and removes their backgrounds. • The procedure is non-destructive, so it preserves evidence for further analysis. • The method is flexible and robust against measurement errors. • The proposed instrument is inexpensive which makes it accessible for any crime lab. • The Mueller polarimeter is portable so it is suitable for crime scene work. In this article we have explored the use of Mueller polarimetry for the simultaneous and non-destructive latent fingerprint development and background elimination. This proposal not only expands previously reported uses of the polarization state of light for fingerprint development, but offers some advantages. Samples of a few donors, taken on different heavily back grounded substrates, were measured and processed. Several strategies for background removal were applied. The results are very promising, since the background was successfully erased in all cases and the quality of the developed fingerprints was excellent for most substrates and donors. Considering that the method is non-destructive and that the proposed measurement instrument is inexpensive and portable the method could be tried in real cases with no risk for the evidence. In addition, the success of the procedure for background removal raises the possibility of exploring if it would work for the enhancement of fingerprints developed with other methods. [ABSTRACT FROM AUTHOR]

Accuracy of using implant length on periapical radiographs as calibration reference for measurements has not been verified. This study aimed to verify the measurements of peri-implant crestal bone level (piCBL) on periapical radiographs taken by the paralleling technique and using the implant length for calibration; and to propose a customized crownlevel position (CLP) jig to improve the measurement accuracy of piCBL. A typodont installed an implant and a screw-retained crown at maxillary central incisor was used. To simulate piCBL, a metal post was placed near the implant at the same height of implant platform. The CLP jig was designed and 3-dimensionally printed out to allow implant projected orthogonally on periapical film. Thirty periapical radiographs were taken using paralleling technique with and without the jig by three examiners. The implant axis and implant length on radiographs were acquired by image segmentation. The discrepancy of piCBL determination (Δ D) from these measurements were compared and further analyzed when using the implant length for calibration. The piCBL measurement errors were smaller when the jig was used for all examiners (P < 0.001). The inter-rater differences were insignificant. After calibration, Δ D with and without jig were 0.09 (0.07–0.11) and 0.43 (0.38–0.49) mm, respectively. Conventional long-cone paralleling technique using true implant length for calibration demonstrated imprecise piCBL measurement on periapical radiographs. Transferring the implant axis to the CLP jig allowed orthogonal projection of radiography which provided reliable measurements of piCBL with an accuracy of less than 0.1 mm. [ABSTRACT FROM AUTHOR]

In this paper, a brain-like navigation scheme based on fuzzy kernel C-means (FKCM) clustering assisted pyramid Lucas Kanade (LK) optical flow algorithm is developed to measure the position of vehicle. The Speed Cell and Place Cell in animals' brain are introduced to construct the brain-like navigation mechanism which involves the optical flow method and image template matching to imitate the cells above-mentioned separately. To eliminate the singular values during optical flow calculation, the output of pyramid LK algorithm is clustered by FKCM algorithm firstly. Then, the velocity is calculated and integrated to get the position of the vehicle, and the brain-like navigation scheme is introduced to correct the position measurement errors by eliminating the accumulated errors resulting from velocity integration. The prominent advantages of the presented method are: (i) a pure visual brain-like position measurement method based on the concept of speed cells and place cells is proposed, making visual navigation more accurate and intelligent; (ii) the FKCM algorithm is used to eliminate the singular value of the pyramid LK algorithm, which improves the calculated velocity accuracy. Also, experimental comparison with classical pyramid LK algorithm is given to illustrate the superiority of the proposed method in position measurement. • Analyzed impact of clustering algorithms on optical flow precision. • Achieved notable reduction in optical flow singular value. • Brain-like navigation minimizes velocity integral errors. [ABSTRACT FROM AUTHOR]

To determine minimal clinically important differences (MCIDs) for the DyNaChron chronic rhinosinusitis quality-of-life questionnaire. MCIDs are the smallest changes in a quality-of-life score that are of clinical relevance for the patient. They allow treatment benefit to be estimated. MCIDs have not previously been determined for DyNaChron. A single-center retrospective study analyzed DyNaChron questionnaires filled out between June 2016 and December 2021 by all patients consulting for chronic nasal dysfunction. Five hundred and thirteen of the 2390 patients were operated on for nasal polyposis (NP; n = 282) or septo(rhino)plasty + inferior turbinoplasty (SPIT; n = 231). Standard error of measurement was used to determine MCIDs. MCID for DyNaChron global score was 60 in NP and 58 in SPIT. MCIDs per symptom domain in NP and SPIT respectively were: 15 and 13 for nasal obstruction, 21 and 21 for anterior rhinorrhea, 20 and 19 for posterior rhinorrhea, and 17 and 17 for olfaction. In agreement with global MCID, 257 NPs (91%) and 149 SPITs (65%) showed clinical improvement. MCID helps assess response to treatment. In the DyNaChron questionnaire, MCIDs enable global and symptom-specific assessment of chronic nasal dysfunction and its impact on quality of life in a single patient or in groups. [ABSTRACT FROM AUTHOR]

Thin-film thermocouples are used as temperature detection components in aircraft engines. However, the preparation of traditional thin-film thermocouples is complex, and their high-temperature stability performance attributes are poor. In this study, polymer-derived ceramic (PDC) technology is introduced to prepare polymer-derived ceramic thin-film thermocouples. Due to the superior high-temperature and adhesion performance characteristics of polymer-derived ceramics and the protective effects of the products of polymer precursors on the thin films, the performance attributes of thin-film thermocouples are greatly improved. After simplifying the preparation process and outputting a large thermoelectric potential, the polymer-derived ceramic thin-film thermocouple exhibits good repeatability, stability, and thermoelectric potential output consistency. At 1200 °C, the peak output is 203 mV, and the average Seebeck coefficient is approximately 182 μV/°C. The temperature measurement error is 0.316%. In the 8-h drift test, the coefficient first increases at 1.26 °C/h and then steadily decreases at −0.63 °C/h. This polymer-derived ceramic thin-film thermocouple has excellent performance and can be applied to the in situ monitoring of thermal components in high-temperature and harsh environments, such as engines. [ABSTRACT FROM AUTHOR]

Line-of-Sight (LoS) navigation is an optical navigation technique that exploits the direction to visible celestial bodies, obtained from an onboard imaging system, to estimate the position and velocity of a spacecraft. The directions are fed to an estimation filter, where they are matched with the actual position of the observed bodies, retrieved from onboard stored ephemerides. As LoS navigation represents a really promising option for the next-generation deep-space spacecraft, the objective of this work is to provide new insights into the performance. First, the information matrix is analyzed to show the influence of the geometry between the spacecraft and the observed planet(s). Then, a Monte Carlo approach is used to investigate the influence of measurement error (ranging from 0.1 to 100 arcsec), and tracking frequency (ranging from four observations per day to one observation every two days). The effect on navigation performance is quantified by two indicators. The first is the 3D position and velocity Root-Mean-Square-Errors, computed once the estimation is considered to be steady-state. The second is the convergence time, which quantifies the required time for the estimation to reach the steady-state behaviour. The simulation is based on a set of four planets, which do not follow the common heliocentric dynamics but rotate around the Sun with the same (distance-independent) angular velocity of the spacecraft. This approach allows the separation of scenario-dependent behaviours from navigation intrinsic properties, as the same relative geometry between observer and observed objects is maintained during the whole simulation. The results provide a useful guide for the next-generation autonomous navigation system, for both the definition of hardware requirements and the design of an appropriate navigation strategy. Considerations are then applied to Near-Earth Asteroid fly-by mission scenarios for the definition of the navigation strategy and hardware requirements. It is shown the importance of relative angles between the spacecraft and the planets. In the single-planet observation scenario, when the angle between the position vectors of the spacecraft and planet approaches a null value, the estimation error decreases. In the double-planets observation scenario, when the separation angle between the two LoS directions gets close to 90°, the estimation error decreases. The main influence on the performance is driven by the measurement error, which with current technologies is shown to be able to provide a position error in the order of a few hundred kilometers, while with a lower measurement error (0.1 arcsec) it would be possible to have a position error below 100 km. Finally, it is demonstrated that tracking frequency plays a secondary role in the performance, and only influences tangibly the convergence time. [ABSTRACT FROM AUTHOR]

The aim of this study was to conduct a systematic review of the psychometric properties of Pressure Pain Detection Threshold (PPDT) measures in people with hand or wrist injuries. MEDLINE, Embase, and CINAHL databases were searched to identify eligible studies evaluating psychometric properties of PPDT in samples composed of at least 50% of people with hand or wrist injury. The Consensus-based Standards for the Measurement of Health Instruments' risk of bias checklist was used to critically appraise the included studies, and qualitative synthesis was performed by pooling the results of all studies that presented the same measurement property using Grading of Recommendations, Assessment, Development, and Evaluation. From 415 studies, 11 relevant studies were identified. Of the 11 studies, four hand or wrist injuries were represented; carpal tunnel syndrome, distal radius fractures, osteoarthritis, and complex regional pain syndrome. Intra-rater reliability was considered sufficient (intraclass correlation coefficient 0.64-0.94), with small reported standard error of the mean values (5.3-39.2 kPa). Results of validity and responsiveness could not be synthesized due to heterogeneity. Risk of bias for reliability and measurement error was assessed as very good or adequate, whereas validity and responsiveness were doubtful or inadequate. Overall quality of evidence was low or very low for all measurement properties. Inconsistent results and low quality evidence provide little confidence in the overall measurement properties of PPDT in a hand or wrist injury population. No criterion standard for pain further highlights complexities around pain measurement such that the results obtained from PPDT measures in clinical practice cannot be compared to a gold standard measure. • Pain represents a challenge to measure as it is a highly subjective, latent construct that cannot be directly observed. • Pressure pain detection threshold (PPDT) is one such tool used by health care professionals and researchers to obtain measures of mechanical pain sensitivity in deep somatic structures. • Our results demonstrated moderate to high intra-rater reliability of PPDT. • Moderate correlations between PPDT, NPRS, and BCTQ indicate that an increased sensitivity to pain is associated with worse functional scores. • Lack of a priori hypotheses highlight complexities around pain measurement and the lack of criterion measures of pain. [ABSTRACT FROM AUTHOR]

This paper investigates the prescribed-time leader-following output-feedback consensus problem for second order multiagent systems without velocity measurement. Firstly, by introducing a time-scaling function, novel prescribed-time state observers are designed to estimate the second-order states of the agents. Then, a distributed output-feedback scheme is proposed to achieve leader-following consensus, where the transient performance, including the convergence rate and the overshoot, can be offline pre-assigned. It should be noted that the singularity-like problem is solved for the system under measurement errors by adopting a form of piecewise functions. Moreover, the control strategy is modified by introducing an auxiliary system when taking the common saturation problem into account. Finally, the efficiency of the proposed schemes is illustrated by numerical simulation examples. • A novel kind of prescribed-time performance functions is designed. • A form of sine functions is introduced to deal with the singularity-like problem. • The prescribed-time stability of the system is guaranteed by the proposed scheme. [ABSTRACT FROM AUTHOR]

Measuring dynamic force is essential for improving equipment accuracy in the aerospace industry. This work presents a self-decoupled, load-sharing-based measurement platform for measuring dynamic force from large sources. Utilizing a load-sharing column increases the rigidity and load capacity of the platform. The measurement principle is thoroughly described. Moreover, the effects of the structural parameters of the platform on performance are then analyzed using finite element analysis, while the feasibility of the measurement principle is verified and an optimal set of structural parameters is obtained using response surface methodology. Finally, the load-sharing-based measuring platform is manufactured based on the analysis. According to the experimental findings, the proposed platform with the column has a 59.7% higher load capacity and a measured fundamental frequency of 1696 Hz. The measuring platform also exhibits strong static and dynamic linearity, high self-decoupling, and an average dynamic measurement error of less than 6%. • A load-sharing element is used to improve the basic performance of the platform. • The measurement method and theoretical models of the platform are derived. • Platform performance and model accuracy are balanced by response surface methodology. • The measurement method, theoretical models and optimization approach are verified experimentally. [ABSTRACT FROM AUTHOR]