Causes Of Measurement Error Research Articles

Error analysis and correction strategy for measuring oriented silicon steel by SST method

AbstractTo accurately determine the relationship between magnetic polarisation and magnetic field strength in oriented silicon steel, the magnetic properties, such as power loss, were measured under different magnetisation conditions. This facilitates for the precise selection of iron core materials for distribution transformers. The deviation rate of measurement results for different magnetisation conditions in oriented silicon steel with varying thicknesses was analysed using the SST method. Additionally, the finite element simulation of MagNet was employed to further investigate this relationship. The causes of measurement errors in oriented silicon steel by the SST method are thoroughly studied, with a focus on 0.18 mm oriented silicon steel as an example. It is found that the main reason for the measurement error is the deviation between the actual effective magnetic path length and the conventional effective magnetic path length, which is caused by the uneven distribution of magnetic polarisation in oriented silicon steel. The main reason for the difference of magnetisation conditions is the change in the actual effective magnetic path length, which is mainly affected by changes in permeability. Combined with the magnetic field distribution inside the oriented silicon steel, the distribution coefficient of magnetic polarisation can be calculated, the actual effective magnetic path length under each condition can be calculated, and then the measurement results of the SST method can be modified. This research is expected to significantly contribute to the practical applications of oriented silicon steel in engineering.

Validation of an abbreviated Big Five personality inventory at large population scale: Psychometric structure and associations with common psychiatric and neurological disorders

BackgroundThe five-factor model of personality, as quantified using instruments such as the Big Five Inventory, consists of broad personality domains including Extraversion, Agreeableness, Conscientiousness, Neuroticism (emotional instability), and Openness. Such instruments typically include >40 items. However, instruments with many items can be unwieldly and a cause of measurement error in clinical and cohort studies where multiple scales are sequenced. Conversely, established 5- and 10-item versions of the Big Five Inventory have poor reliability. Here, we developed and validated an abbreviated 18-item Big Five Inventory that balances efficiency, reliability and sensitivity. MethodWe analysed three datasets (N = 59,797, N = 21,177, and N = 87,983) from individuals who participated in the online Great British Intelligence Test (GBIT) study, a collaborative citizen science project with BBC2 Horizon. We applied factor analyses (FA), predictive normative modelling, and one-sample t-tests to validate the 18-item version of the Big Five and to investigate its associations with psychiatric and neurological conditions. ResultsThe 18-item version of the Big Five Inventory had higher validity and retest reliability compared to the other previously shortened versions in the literature, with comparable demographic associations to the full Big Five Inventory. It exhibited strong (i.e. large effect size) associations with psychiatric conditions, and moderate (small-medium) associations with neurological conditions. Neuroticism (emotional instability) was substantially higher in all psychiatric conditions, whereas Conscientiousness, Openness and Extraversion showed differential associations across conditions. ConclusionThe newly validated 18-item version of the Big Five provides a convenient means of measuring personality traits that is suitable for deployment in a range of studies. It retains psychometric structure, retest reliability and clinical-group sensitivity, as compared to the full original scale.

Data quality processing for photovoltaic system measurements

The operation and maintenance activities in photovoltaic systems use meteorological and electrical measurements that must be reliable to check system performance. The International Electrotechnical Commission (IEC) standards have established general criteria to filter erroneous information; however, there is no standardized process for the evaluation of measurements. In the present work we developed 3 procedures to detect and correct measurements of a photovoltaic system based on the single diode model. The performance evaluation of each criterion was tested with 6 groups of experimental measurements from a 3 kWp installation. Based on the error of the 3 procedures performed, the most unfavorable case has been prioritized. Then, the reduction of errors between the estimated and measured value has been achieved, reducing the number of measurements to be corrected. For the clear sky categories, the coefficient of determination is 0.9975 and 0.9961 for the high irradiance profile. Although an increase of 2.5% for coefficient of determination has been achieved, the overcast sky categories should be analyzed in more detail. Finally, the different causes of measurement error should be analyzed, associated with calibration errors and sensor quality.

Combining error models to reduce the imprecision of geometric length measurement in vector databases

AbstractLength measurements calculated from the geometry of vector geographic objects, called geometric measurements, are inherently imprecise. The imprecision of the measurements is due to the accumulation of causes of various origins, related to the production processes, and the rules of data representation. In order to reduce the overall imprecision of geometric length measurements, this article proposes to identify the causes of measurement error in the data, to model their respective impact, and finally to combine these different impacts. To do so, five causes of geometric measurement error have been modeled: map projection, terrain disregard, polygonal approximation of curves, digitizing error, and cartographic generalization. To estimate the overall measurement imprecision, three combination methods are proposed: selection of the maximum error, sum of the errors, and quadratic aggregation of the errors. An experiment conducted on a sample of roads represented at a medium scale demonstrates that quadratic error aggregation is the most effective combination method for reducing the imprecision of geometric length measurements.

Impacts on X-ray fluorescence measurements for rapid determination of the chemical composition of renewable solid biofuels

Rapid determination of quality parameters in solid biofuels enables transparent fuel trading and optimised plant operation, e.g. due to lower plant operating costs and lower air pollutant emissions. The present study investigates the impact of interferences caused by the chemical composition, particle size, water content, and measuring time on the rapid measurement technique X-ray fluorescence analysis for solid biofuels. The elements investigated are the minor elements Na, Mg, Si, P, S, Cl, K, Ca and the trace elements Al, Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, As Cd, Pb as described in ISO 17225-1. The results provided new insights into the cause of measurement errors and also similarities with findings from other fields. Specifically, we found that grain size <1 mm in sample preparation and water content ≤10 % had a clear benefit on the measurement. In the case of samples with high mineral content, interferences between the elements Si and P occur. Furthermore, the results show that the measurement time for the actual measurement can be significantly reduced to 60 s compared to the factory setting (i.e. from 750 s). The findings of the study contribute to reducing or preventing the indicated measurement errors in future XRF analysis.

A full 6 degree-of-freedom visual estimation with laser assisted

Efficient and accurate measurement in unstructured environment is a challenging issue and also research interest in the industrial field. The accuracy of vision is very high in the close-range scene and the stability of laser measurement is better, with a large achievable range. A 6-DOF pose measurement method based on vision and assisted by laser is proposed in this paper. By combining their respective advantages, the method can be immune to ambient light. The optimization objective is established by using the projection coordinates of laser spots in different coordinate systems and solved by Newton–Raphson iteration. The initial value is estimated by Kronecker product. The Monte Carlo method is further used to simulate. The causes of measurement errors and the influence factors affecting the accuracy are analyzed. On this basis, an experimental prototype is constructed. The accuracy and repeatability accuracy experiments are conducted to verify the correctness of the proposed method.

Physics-based recalibration method of cup anemometers

Cup anemometer is the most widely used instrument in the natural environment. However, the accuracy of cup anemometer is not robust due to their inertial structures. In this study, the equation of motion (EOM) relating rotational motion of the cup rotor to aerodynamic force is investigated to reveal the cause of measurement error of cup anemometer. A new methodology is proposed to recalibrate cup anemometer based on theoretical analysis of the dynamic response of the cup rotor and random process theory. The unknown dynamic coefficients of the EOM are quantified by the numerical method using measurement results from inertial and non-inertial anemometers. A detailed example is presented to demonstrate the efficiency of this new method in which coefficients of the EOM are quantified from laboratory and field data. Both mean wind speed and the entire time history could be recalibrated using this new method. Comparing with the non-inertial anemometer results, the improvement rate of the recalibrated cup anemometer results is 29%–99%.

Instrumentation Techniques for the Measurement of Gunfire

The peak sound pressure from near-field small arms gunfire is commonly used when assessing a shooter's hearing damage risk. Close to a shooter's ear, the peak sound pressure level from a rifle or pistol can be 155-to-160 decibels with a pulse rise time on the order of ten microseconds. Standard dosimeters equipped with conventional measurement microphones significantly under-report the true peak levels from proximate gunfire; hence, the shooter's exposure is either unknown or underestimated. The U.S. Military has established exposure limits for small arms gunfire; however, the specified properties of the measurement instrumentation are more prescriptive than performance-based. The implication is that the practitioner is responsible for pre-qualifying his or her own instrumentation. For near-field gunfire, the leading cause of measurement error occurs when the wide-band signal from the acoustical transient is transduced by a relatively large-diameter measurement microphone having limited bandwidth. Secondary measurement errors include the finite bandwidth of the microphone signal amplifier and its slewing limit, the characteristics of the anti-aliasing filter used, and the sampling rate of the digital recording device. The paper discusses these instrumentation constraints and recommends minimum performance requirements to help attain reproducible measurements of small arms gunfire.

Design and accuracy test of equatorial moment of inertia test equipment for projectile and rocket

The moment of inertia is an important mass characteristic parameter. The precise measurement of the moment of inertia is a necessary step to study and control the flight orbit and attitude of missiles. To measure the equatorial moment of inertia of large projectiles, this paper uses the torsion pendulum method to measure the equatorial moment of inertia of large projectiles and deeply analyzes the measurement principle. The causes of measurement error are analyzed, and the measurement accuracy of the equipment is verified by experiments. The maximum relative error is less than 1 %, and the relative uncertainty is 1.3926 %, which meets the requirements of expected technical indicators.

Radiological evaluation of patellofemoral instability and possible causes of assessment errors.

Patellofemoral instability (PI) is the disruption of the patella’s relationship with the trochlear groove as a result of abnormal movement of the patella. To identify the presence of PI, conventional radiographs (anteroposterior, lateral, and axial or skyline views), magnetic resonance imaging, and computed tomography are used. In this study, we examined four main instability factors: Trochlear dysplasia, patella alta, tibial tuberosity–trochlear groove distance, and patellar tilt. We also briefly review some of the other assessment methods used in the quantitative and qualitative assessment of the patellofemoral joint, such as patellar size and shape, lateral trochlear inclination, trochlear depth, trochlear angle, and sulcus angle, in cases of PI. In addition, we reviewed the evaluation of coronal alignment, femoral anteversion, and tibial torsion. Possible causes of error that can be made when evaluating these factors are examined. PI is a multi-factorial problem. Many problems affecting bone structure and muscles morphologically and functionally can cause this condition. It is necessary to understand normal anatomy and biomechanics to make more accurate radiological measurements and to identify causes. Knowing the possible causes of measurement errors that may occur during radiological measurements and avoiding these pitfalls can provide a more reliable road map for treatment. This determines whether the disease will be treated medically and with rehabilitation or surgery without causing further complications.

IDENTIFICATION AND PROCESSING OF DATA ANOMALIES IN MACHINE LEARNING TASKS

The paper presents the procedure of identification and processing of data anomalies at the stage of preliminary data processing in machine learning tasks. The procedure consists of three stages. At the first stage, emissions are detected in the data samples. A large number of methods are used for this. The choice of a particular method depends on the task of machine learning, the structure of the data set and the types of data being processed. The methods used at this stage are methods of statistical tests, methods of metric tests, methods of model tests, iterative methods, methods of machine learning, ensemble methods. Until the second stage, the analysis of the causes of emissions is carried out. The causes of emissions include: causes of measurement errors and causes of data processing errors, the results of external influences, or errors in data records. In the third stage, there is a final processing of data sets with emissions, in which there is a removal of emissions or normalizing transformations. The effectiveness of the procedure was tested on different data sets.

The accuracy of portion size estimation using food images and textual descriptions of portion sizes: an evaluation study.

BackgroundInaccurate self‐report of portion sizes is a major cause of measurement error in dietary assessment. To reduce this error, different portion size estimation aids (PSEAs) have been developed, including food images (image based, IB‐PSE) and textual descriptions of portion sizes (text‐based, TB‐PSE). We assessed the accuracy of portion size estimation by IB‐PSE and TB‐PSE.MethodsTrue intake of one lunch was ascertained in forty participants. Self‐reported portion sizes were assessed after 2 and 24 hours by means of TB‐PSE and IB‐PSE, in random order. Wilcoxon's tests were used to compare mean true intakes to reported intakes. Moreover, proportions of reported portion sizes within 10% and 25% of true intake were assessed. An adapted Bland‐Altman approach was used to assess agreement between true and reported portion sizes. Analyses were conducted for all foods and drinks combined and for predetermined food types.ResultsNo significant differences were observed between reported portion sizes at 2 and 24 hours after lunch. Combining median relative errors of all foods items resulted in an overall 0% error rate for TB‐PSE and 6% error rate for IB‐PSE. Comparing reported portion sizes within 10% (31% vs. 13%) and 25% (50% vs. 35%) of the true intake showed a better performance for TB‐PSE compared to IP‐PSE, respectively. Bland‐Altman plots indicated a higher agreement between reported and true intake for TB‐PSE compared to IB‐PSE.ConclusionsAlthough the use of TB‐PSE still results in measurement error, our results suggest a more accurate dietary intake assessment with TB‐PSE than IB‐PSE.

High-Precision Extraction Method for Blade Tip-Timing Signal with Eddy Current Sensor

Online monitoring of high-speed rotating blades has always been a hot topic. Of the various methods, the blade tip timing (BTT) technique, based on eddy current sensors, is considered to be the most promising. However, BTT signals are easily influenced by various factors, which means that the accurate extraction of BTT signals remains a challenge. To try to solve this problem, the causes of measurement error were analyzed. The three main reasons for the error were established: the variation in blade tip clearance, the interference of background noise, and the asymmetry of the blade tip shape. Further, pertinent improvement methods were proposed, and a compensation method was proposed for the errors caused by the variation of tip clearance. A new denoising and shaping algorithm based on ensemble empirical mode decomposition (EEMD) was introduced for the errors caused by background noise. Additionally, an optimal installation position of the sensor was also proposed for the errors caused by the asymmetry of the blade tip shape. Finally, simulations and experiments were used to demonstrate the improved methodology. The results show that the measurement error on vibration amplitude and vibration frequency using the proposed method is less than 2.89% and 0.17%, respectively, which is much lower than the traditional method (24.44% and 0.39%, respectively).

Measurement system analysis in angle of repose of fertilizers with distinct granulometries

This research presents an experimental study for measurement system analysis of angle of repose in fertilizers with variable granulometry (1.5 mm < d50 < 5.0 mm). In the literature, there are different procedures for determining this angle of repose, which often result on a variety of measurements for one measurand. Thus, the main objective of this work is to propose a method for measurement system validation of angle of repose. The statistical validation was based on Nested Gage Repeatability and Reproducibility (NGR&R) and the experiment was conceived through a technical apparatus built to measure the angle of repose of fertilizers. Experiments was conducted by using available resources in a typical industrial laboratory of fertilizer characterization. Among the measuring procedures, the fixed funnel has been used and an image analyzer software has been adopted to gather the data. The experiment was planned with 3 (three) operators, 10 (ten) samples with distinct granulometries and 3 (three) replicates. The result analysis has shown that the measurement error through the first measuring procedure was deemed unacceptable. After investigating the root cause of measurement error, a new standard measurement procedure was proposed. The new procedure was able to measure the angle of repose precisely, reducing measurement error from 59.93% to 4.82%.

Response to exercise-induced blood pressure elevation is blunted in wrist-cuff automated oscillometric measurement in healthy young college students.

BackgroundA wrist‐cuff automated oscillometric device is portable and useful for self‐monitoring of blood pressure (BP) at home and outdoors when an upper arm device is not available. Although the height of the forearm in wrist BP measurement is acknowledged to be the major cause of measurement error, it remains unclear whether exercise affects subsequent wrist BP measurement.Methods and ResultsNinety‐seven healthy college students (median age of 20 years with an age range of 19 to 36 years, 70.1% males) participated in this study. Care was taken to keep the position of the wrist at a level near the upper arm level in BP measurement. At rest, BP measured by a wrist‐cuff oscillometric device (Omron HEM‐6183) was generally acceptable when it was compared with BP measured by an upper arm oscillometric device (Omron HEM‐7130‐HP) and with BP measured by the auscultatory method using a mercury sphygmomanometer. However, the ratio of systolic BP measured by oscillometric devices just after a two‐step exercise test to that before exercise on the wrist (1.22 ± 0.14) was significantly lower than the ratio on the upper arm (1.27 ± 0.14), and the difference was significantly correlated with exercise‐induced increase in pulse rate (Spearman's ρ = 0.23), suggesting a possible role of autonomic nerve activity in the blunted response to exercise‐induced BP elevation in wrist BP measurement.ConclusionsThe results indicate that the blunted response to exercise‐induced BP elevation should be considered in wrist BP measurement when using a wrist‐cuff oscillometric device.

Exploration of temperature effect on videogrammetric technique for displacement monitoring

There has been a sustained interest towards the non-contact structural displacement measurement by means of videogrammetric technique. On the way forward, one of the major concerns is the spurious image drift induced by temperature variation. This study therefore carries out an investigation into the temperature effect of videogrammetric technique, focusing on the exploration of the mechanism behind the temperature effect and the elimination of the temperature-caused measurement error. 2D videogrammetric measurement tests under monotonic or cyclic temperature variation are first performed. Features of measurement error and the casual relationship between temperature variation and measurement error are then studied. The variation of the temperature of digital camera is identified as the main cause of measurement error. An excellent linear relationship between them is revealed. After that, camera parameters are extracted from the mapping between world coordinates and pixels coordinates of the calibration targets. The coordinates of principle point and focal lengths show variations well correlated with temperature variation. The measurement error is thought to be an outcome mainly attributed to the variation of the coordinates of principle point. An approach for eliminating temperature-caused measurement error is finally proposed. Correlation models between camera parameters and temperature are formulated. Thereby, camera parameters under different temperature conditions can be predicted and the camera projective matrix can be updated accordingly. By reconstructing the world coordinates with the updated camera projective matrix, the temperature-caused measurement error is eliminated. A satisfactory performance has been achieved by the proposed approach in eliminating the temperature-caused measurement error.

ПРО ВМІСТ, МІГРАЦІЮ ТА КОНЦЕНТРАЦІЮ ВАЖКИХ МЕТАЛІВ У НАФТАХ (на прикладі Дніпровсько-Донецької западини)

Literature review and analysis of previous studies of the problem was carried. The main scientific works on the research topic, as well as the main directions and stages of the study are indicated. Similar studies that were conducted on the territory of Ukraine are considered. The results of the study of heavy metals in oil samples taken from a large oil and gas region from more than thirty deposits of Ukraine are presented. All current and non-working fields are considered. The geological structure of the oil and gas province, as well as the main geochemical features of the formation of mineral deposits are considered. The main forms of finding target metals, as well as possible ways of transferring these elements in the earth’s crust are given. Samples were investigated using x-ray fluorescence and neutron activation analysis. The obtained research data in the framework of two selected methods are combined for analysis. The results obtained within the same geological structure are compared with each other to determine the effect of the physical conditions of sediment formation on the microcomponent composition of crude oil. They also compared the effect of physical conditions on the properties of oil and their ability to accumulate heavy metals. Possible causes of the abnormal accumulation of heavy metals due to the close occurrence of oil and formation water are noted. According to the results obtained, a graph is constructed of the dependence of the mineralization of oil on its depth. An exponential graphical approximation is presented to display the general trend of dependence. Possible sources and ways of migration and accumulation of heavy metals in hydrocarbons are analyzed. The concept of the migration of heavy metals in oil is proposed in conjunction with the ore mineralization of adjacent and adjacent deposits. Possible causes of differences in the concentrations of heavy metals in oil of various geological structures are indicated, as well as the main possible causes of measurement errors and complications in the selection of each of the analysis methods are specified.

Development of main components of device for measuring residual stresses

The paper presents the results of the study of the stress state of machine elements and structures in which there are residual stresses. Examines the use of overhead eddy current and magneto-elastic transducers, investigates the process of measurement of residual stresses. It is proved that the cause of measurement errors is the instability of the gap between the transducer and the surface of the object. It is proved that during calibration and measurements, the installation of the gap and its control should be carried out by the magnitude of the magnetic resistance. Undesirable effects of variable electromagnetic properties of the object material on the installation result can be eliminated by using the method of vortex currents. As a result, a device for measuring the stress state of objects made of ferromagnetic metals has been developed, which uses a magnetoelastic converter. Using the values of the frequency increment of the corresponding oscillator, it is possible to significantly reduce the impact of changes in operating conditions on the measurement result.

The Challenges of Organizational Classification: A Research Note

Social movement, civil society, and world polity scholars use counts of nongovernmental organizations (NGOs) to evaluate important theoretical and empirical claims. To construct these measures, researchers often classify NGOs by their goals and/or domains. However, over time, the ways organizations describe and orient themselves change, blurring boundaries between organizations and complicating measurement. In this research note, we identify methodological challenges of organizational classification in the context of our work constructing a longitudinal dataset of transnational social movement organizations. We draw attention to an understudied cause of measurement error: overcounting of organizations. We suggest that as automated methods for classifying data become widespread, devising strategies for dealing with these challenges becomes even more pressing.

Stability of the Manual Ability Classification System in young children with cerebral palsy.

To examine the stability over time of the Manual Ability Classification System (MACS) levels in children with cerebral palsy (CP) aged 18 to 60months. This was a prospective longitudinal population-based study of 252 Australian children (160 males [63%] 92 females [37%]; mean age [SD] 41.7mo [14], range 17.2mo-69.2mo) with CP. Children were classified at 18months (n=70), 24 months (n=131), 30months (n=173), 36months (n=209), 48months (n=226), and 60months (n=221) of age. Stability of the MACS was examined using the proportion of specific positive agreement and transition proportions, which are measures of agreement. There were 1030 unique observations, with each of the 252 participants seen between two and six occasions (median=4). Average specific positive agreement over the study period was 76% for MACS level I, 67% for level II, 50% for level III, 51% for level IV, and 83% for level V. MACS levels I and V have the highest degree of stability, while levels III and IV have the lowest. We show how this may be explained by the proportion of children in each MACS level. Using measures of agreement rather than measures of reliability provides accurate information when measuring stability over time of an ordinal classification system. The relative stability of MACS levels can be explained by the proportion of children in each level. Children classified in Manual Ability Classification System (MACS) levels III and IV change levels at next assessment about 50% of the time. Children should be assessed with the MACS regularly, particularly those in levels III and IV. Stability within ordinal classification level categories can be predicted using a measurement error model. Transition proportions or specific agreement is recommended for reporting stability of ordinal classification systems.