Errors In Direct Measurements Research Articles

Effect of K+ Concentration on the Direct pH Measurement of Peat Matrix by Sb Electrode pH Sensor and Compensation Methods

pH of the substrate for soilless cultures is crucial information. As comparison to laboratory analysis, direct pH measurement with an all-solid-state pH sensor is quicker, more cost-effective, and more accurate. There are a variety of impacting factors and measuring inaccuracies, though. Peat was utilized as the test item in order to examine the variables and regulations affecting the measurement error and minimize it. Using KCl solution, substrate specimens with various mass water contents (MWC) and K <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> concentrations (C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">K+</sub> ) were created. Using an alumina substrate, a Sb working electrode and an Ag/AgCl reference electrode were created to form an all-solid-state pH sensor. On the basis of the direct pH measurements of peat substrate, it was used to investigate the error patterns of MWC and C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">K+</sub> . A statistical examination of the measured pH values revealed that MWC and C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">K+</sub> clearly affected the pH of the peat’s direct measurement error. The greatest inaccuracy is 0.98 pH units when C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">K+</sub> is 0 M and MWC is 0.2, and it progressively declines as MWC is increased. The inaccuracy is 0.39 pH units when C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">K+</sub> is 0.1 M. From 0 to 0.1 M, the measurement error falls linearly as C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">K+</sub> is increased. A double compensation model of MWC and C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">K+</sub> was constructed using statistical analysis, and after compensation, the maximum error of the pH of peat substrate was decreased from 1.05 to 0.41. For the purpose of furthering the development of an all-solid-state pH sensor in practice, the work offers a theoretical and experimental foundation.

Analysis of Product Quality and Service Quality on Customer Satisfaction at the Surya Mart Mart Business Center using the Structural Equation Modeling Method

Service quality is a superior value for customers to improve business performance or company marketing represents a level of excellence to meet consumer expectations. Therefore, it is not necessary to know what factors affect product quality and service quality at the Surya Mart Business Center Surya Mart Business Center. Surya Mart Business Center Surya Mart's Business Center is located on campus 2 of the Muhammadiyah University of Sidoarjo (UMSIDA), the market is for students, lecturers, UMSIDA employees and the surrounding community. To find out the factors that affect product quality and service quality, research uses Structural Equation Modeling, which is ia statistical technique that is able to analyze the pattern of relationships between data constructs and indicators, one data construct and another, and direct measurement errors. The results showed that the highest loading factor value was 1.329 in the discount indicator, for the term indicator, namely the additional factor with a value of 0.664. Test structural modeling on the relationship between constructs that have a casual or causal relationship. The results of this study, Variable Product Quality and Service Quality, the second variable has a significant influence on the Customer Satisfaction variable.

Analysis and Measurement of Static Deflection of Water Pump Rotor

The method of obtaining the maximum value of static deflection based on least square method curve fitting is introduced which is more accurate than the direct measurement data. The static deflection measurement data of the pump rotor were simulated using a simply supported beam as an example by adding errors in the data. The accuracy and rationality of cubic spline fitting and polynomial fitting in static deflection measurement were compared. The error might increase by using the cubic spline fitting when there are measurement errors. The error of static maximum deflection value after polynomial fitting is reduced to 27.8% of the direct measurement error, and the accuracy is better than that of the nearest measured point data instead of the static maximum deflection. The finite element simulation of pump rotor is carried out by using ANSYS in this paper to verify the feasibility.

Reliability and minimal detectable change in foot pressure measurements in typically developing children

BackgroundIn pedobarography, clinically meaningful comparison of measurements within or between subjects is limited by data variability and measurement error. This study aims to determine the components of the minimal detectable change (MDC) in impulse across all foot regions and the reliability of these measures. MethodsA convenience sample of foot pressures from 108 visits by normal, healthy subjects aged 2–17 years was studied. Each subject had three pedobarograph measurements taken per foot, with six subjects returning for a second visit for assessment of day-to-day variability. Using a five-region mask, segmental impulses were determined, and from these we obtained the coronal plane pressure index (CPPI). Inter-rater, intra-rater, and day-to-day data were analyzed using intraclass correlation coefficients (ICC) to quantify reliability. Variability of the data was analyzed to quantify the MDC. ResultsInter- and intra-rater reliability was high for all measurements while variability was low, indicating small direct measurement error. Generally, the largest contributing factor to the MDC was day-to-day variability. Step-to-step variability was more dependent on foot segment than age although minor age-related changes were noted. Finally, the high relative variability in the CPPI and the medial mid foot impulse resulted in very high MDCs for these measures.

Mapping flow distortion on oceanographic platforms using computational fluid dynamics

Abstract. Wind speed measurements over the ocean on ships or buoys are affected by flow distortion from the platform and by the anemometer itself. This can lead to errors in direct measurements and the derived parametrisations. Here we computational fluid dynamics (CFD) to simulate the errors in wind speed measurements caused by flow distortion on the RV Celtic Explorer. Numerical measurements were obtained from the finite-volume CFD code OpenFOAM, which was used to simulate the velocity fields. This was done over a range of orientations in the test domain from −60 to +60° in increments of 10°. The simulation was also set up for a range of velocities, ranging from 5 to 25 m s−1 in increments of 0.5 m s−1. The numerical analysis showed close agreement to experimental measurements.

Validity of the 3D VECTRA photogrammetric surface imaging system for cranio-maxillofacial anthropometric measurements

The use of three-dimensional (3D) photography for anthropometric measurements is of increasing interest, especially in the cranio-maxillofacial field. Before standard implementation, accurate determination of the precision and accuracy of each system is mandatory. A mannequin head was labelled with 52 landmarks, and 28 three-dimensional images were taken using a commercially available five-pod 3D photosystem (3D VECTRA; Canfield, Fairfield, NJ) in different head positions. Distances between the landmarks were measured manually using a conventional calliper and compared with the digitally calculated distances acquired from labelling by two independent observers. The experimental set-up accounted for clinical circumstances by varying the positioning (vertical, horizontal, sagittal) of the phantom. In the entire calliper measurement data set (n = 410), a significant difference (p = 0.02) between the directly measured and corresponding virtually calculated distances was found. The mean aberration between both modalities covering all data was 7.96mm. No differences (p = 0.94) between the two groups were found using a cut-off of 10% (leaving n = 369 distances) due to considerable errors in direct measurements and the necessary manual data translation. The mean diversity of both measurement modalities after cut-off was 1.33mm (maximum, 6.70mm). Inter-observer analysis of all 1,326 distances showed no difference (p = 0.99; maximal difference, 0.58mm) in the digital measurements. The precision and accuracy of this five-pod 3D photosystem suggests its suitability for clinical applications, particularly anthropometric studies. Three-hundred-and-sixty degree surface-contour mapping of the craniofacial region within milliseconds is particularly useful in paediatric patients. Proper patient positioning is essential for high-quality imaging.

Experimental study of plasmonic structures with variant periods for sub-wavelength focusing: analyses of characterization errors

Characterization issues of plasmonic structures are highlighted and investigated in detail in this paper. Combining with the plasmonic structures functioning for sub-wavelength focusing, optical characterization was carried out using a near-field scanning optical microscope (NSOM) system. Characterization errors that originated from both the nanofabrication using a focused ion beam (FIB) direct milling technique and misalignment of the NSOM system were analyzed in comparison to the theoretical computational results. Our experimental results demonstrated that the focusing function of the structures is in agreement with that of the designed structure. However, the measured beam spot size is larger than the designed value due to the direct measurement error originating from the NSOM and the indirect error from the FIB fabrication process.

A note on the using of accounting databases

This paper identifies potential data problems when using accounting databases. To examine data errors, two commonly used accounting databases, Value Line and Compustat, are compared in their qualitative and quantitative features. Data are examined using seven variables over a period of 11 years. Substantial data differences are found, most of which are attributable to definitional discrepancies and others to direct measurement error. Finally, recommendations for dealing with these problems are presented, to preparers of databases as well as standard setters.

Direct Measurement Error Identification and Reporting for Upper Extremity Exposure Assessment

Electrogoniometers currently represent the most feasible way of obtaining direct measurements of wrist and forearm posture and motion in varied work environments. Researchers have shown that a significant amount of error may be present in the recordings from these instruments (Buchholz and Wellman, 1997; Armstrong et al., 1993). This study showed that even with “state of the art” correction methods, wrist flexion/extension and wrist deviation duration measurements may still vary by as much as 100% plus or minus the measured result in the 95% confidence interval. Forearm extreme posture duration intervals were equal to or less than 40% of the calculated values. Wrist flexion/extension and forearm rotation repetition measurements were more accurate, giving confidence intervals plus or minus less than 25% of the resulting values. Wrist deviation repetition confidence intervals were wider, at plus or minus 100% or greater and generally including zero. These results highlight the need to address accuracy when reporting measurements of the upper extremities and to promote further research into the development of accurate measurement methods.

Summation of random and residual systematic components of errors in direct measurements

Some universally adopted procedures for summation of errors in direct measurements are discussed. Conditions under which the methods applied yield noncontradictory results are stated. Practical recommendations for summation of random and residual systematic error components of direct measurements are provided.

Optimizing data usability in the remedial process

AbstractLarge quantities of data are collected and evaluated throughout every stage of the remedial process. The usability of these data is often a function of the perceived “quality” of the data, with good data considered usable and bad data considered unusable. The assessment of data quality and usability has traditionally focused on analytical and other direct measurement errors and uncertainty. However, problems with the data that are measurement‐related are usually a relatively minor portion of the total error and uncertainty.Error and uncertainty are introduced throughout every aspect of any remedial process, including planning errors, measurement errors, and interpretation errors. Although each error component is important, the errors and uncertainty associated with the design, collection, and interpretation of data are often much greater than measurement‐related errors.Nevertheless, there is typically a disproportionate level of effort expended addressing the minor types of measurement errors when compared to other more important error components in the remedial process. However, the key to obtaining optimum data use requires the general redirection of Data Quality Assurance (DQA) activities from measurement‐related errors/uncertainty to other important planning and interpretation elements.The elements considered essential for developing an effective approach for maximizing data usability include: focused project planning activities stressing a rigorous data quality objective process and a geostatistical approach to the design of the data collection program; the development of sensible and appropriate data validation/review objectives; and the development of realistic error and uncertainty limits for measurement/analytical activities.

Estimation of potentialities of methods of summation of direct measurement errors

Conventional methods for summation of direct measurement errors are considered. Conditions under which these methods provide consistent results are stated. It is proposed to utilize for characteristic of the total error, its interval estimator or the half-sum of the value obtained by adding up its arithmetic and geometric random errors.

Il metodo del bootstrap nella propagazione degli errori

This note illustrates, through a very simple example, the power and flexibility of the bootstrap method to assess in a straightforward and unambiguous way how the random errors in direct measurements propagate themselves into the derived quantities of interest. Furthermore, a version of the bootstrap with the initial data set generated by Monte Carlo has proved to be suitable in situations where the standard deviations of the directly measured quantities may be considered as known, but the effect of various experimental errors on the accuracy of final results is quite obscure.

Inversion of flow Measurements for Stress and Rheological Parameters in a Valley Glacier

AbstractMethods are developed for determining the distributions of stress and effective viscosity in a glacier, under the assumptions: the ice is quasi-viscous, the flow is time independent, and acceleration forces are negligible. Measurements of the three-dimensional distribution of velocity are needed for their application. The differential equations of mechanical equilibrium, expressed in terms of viscosity, strain-rate components, mean stress, and their gradients, are viewed as equations to be solved for viscosity and mean stress subject to boundary conditions at the free upper surface. For certain rectilinear flow patterns, unique distributions of stress and effective viscosity can always be derived. For more complicated flow this is not necessarily so. However, it is still possible to choose the best values of rheological parameters in any trial flow law based on the requirement that the residuals to the equations of equilibrium be minimized in a mean-square sense. The techniques are applied to measurements of internal deformation made in nine bore holes on the Athabasca Glacier. At the center line the magnitude of the surface-parallel shear stress increases with depth more slowly than would be expected from a standard shape factor correction or the theoretical distribution of Nye. Correspondingly the lateral distribution of lateral shear stress shows the opposite relationships. In the lower one- to two-thirds of the depth corresponding to a range in effective stress from about 0.5 to 1.2 bars, the gross rheology of the ice is not distinguishably different from the experimentally determined flow law of Glen (n= 4.2,T= 0.02° C) as generalized by Nye. The results do not support the conclusion that the effective viscosity is higher than would be expected from Glen’s experiments as indicated by the more limited measurements of Paterson and Savage. Power-law parameters derived for the different bore holes considered separately show a spread, which suggests some rheological inhomogeneity. However, no definite conclusions can be drawn, because of direct measurement errors at the bore holes and less definable uncertainty in the interpolated distribution of velocity between the holes. The upper one- to two-thirds of the glacier constitutes an anomalous zone in which there is either a strong effect from a complex distribution of stress arising from longitudinal stress gradients or more complicated rheology than in a homogeneous power-law material.

Inversion of flow Measurements for Stress and Rheological Parameters in a Valley Glacier

AbstractMethods are developed for determining the distributions of stress and effective viscosity in a glacier, under the assumptions: the ice is quasi-viscous, the flow is time independent, and acceleration forces are negligible. Measurements of the three-dimensional distribution of velocity are needed for their application. The differential equations of mechanical equilibrium, expressed in terms of viscosity, strain-rate components, mean stress, and their gradients, are viewed as equations to be solved for viscosity and mean stress subject to boundary conditions at the free upper surface. For certain rectilinear flow patterns, unique distributions of stress and effective viscosity can always be derived. For more complicated flow this is not necessarily so. However, it is still possible to choose the best values of rheological parameters in any trial flow law based on the requirement that the residuals to the equations of equilibrium be minimized in a mean-square sense. The techniques are applied to measurements of internal deformation made in nine bore holes on the Athabasca Glacier. At the center line the magnitude of the surface-parallel shear stress increases with depth more slowly than would be expected from a standard shape factor correction or the theoretical distribution of Nye. Correspondingly the lateral distribution of lateral shear stress shows the opposite relationships. In the lower one- to two-thirds of the depth corresponding to a range in effective stress from about 0.5 to 1.2 bars, the gross rheology of the ice is not distinguishably different from the experimentally determined flow law of Glen (n = 4.2, T = 0.02° C) as generalized by Nye. The results do not support the conclusion that the effective viscosity is higher than would be expected from Glen’s experiments as indicated by the more limited measurements of Paterson and Savage. Power-law parameters derived for the different bore holes considered separately show a spread, which suggests some rheological inhomogeneity. However, no definite conclusions can be drawn, because of direct measurement errors at the bore holes and less definable uncertainty in the interpolated distribution of velocity between the holes. The upper one- to two-thirds of the glacier constitutes an anomalous zone in which there is either a strong effect from a complex distribution of stress arising from longitudinal stress gradients or more complicated rheology than in a homogeneous power-law material.

Measurement and Its Reliability: An Introductory Laboratory Experiment

An introductory laboratory experiment about measurement and its reliability has been developed for general science students. The experiment keeps their interest by focusing on the measurement outside the classroom of a quantity of daily interest (speeds of automobiles). It allows simple estimates of direct measurement errors, allows the experiment to be designed accordingly, and stresses the reliability (court room defense) of the measurement of the quantity of interest. At the same time, the kinematical concepts of average velocity, instantaneous velocity, and acceleration can be introduced as can the utility of significant figures and graphical display.