scholarly journals Uncertainty Evaluation for Measurements of Pitch Deviation and Out-of-Flatness of Planar Scale Gratings by a Fizeau Interferometer in Littrow Configuration

2018 ◽  
Vol 8 (12) ◽  
pp. 2539 ◽  
Author(s):  
Xin Xiong ◽  
Yuki Shimizu ◽  
Xiuguo Chen ◽  
Hiraku Matsukuma ◽  
Wei Gao
Keyword(s):  
Uncertainty Analysis ◽  
Evaluation Method ◽  
Uncertainty Evaluation ◽  
Surface Form ◽  
Fizeau Interferometer ◽  
Form Errors ◽  
Final Measurement ◽  
Pitch Deviation ◽  
Littrow Configuration

Form errors of a planar scale grating, such as pitch deviations and out-of-flatness, are major contributors to the final measurement uncertainty of an interferential scanning-type planar encoder. Following the previous work, in which a method has been proposed to evaluate both the out-of-flatness and the pitch deviations of a planar scale grating by a Fizeau interferometer in Littrow configuration, uncertainty analysis on this method is performed in this paper. Theoretical equations are derived to make quantitative uncertainty analysis while taking possible error factors into account. To overcome the drawbacks of a traditional uncertainty matrix approach, a new procedure is proposed to evaluate the uncertainty in the PV (peak-to-valley) deviation of a surface form, so as to assure the quality of measurement. Experiments are finally conducted to demonstrate the feasibility of proposed uncertainty evaluation method.

Uncertainty Evaluation on Multi-Hole Aerodynamic Pressure Probes

2020 ◽  
Author(s):  
Andrea Notaristefano ◽  
Paolo Gaetani ◽  
Vincenzo Dossena ◽  
Alberto Fusetti
Keyword(s):  
Uncertainty Analysis ◽  
Evaluation Method ◽  
Experimental Testing ◽  
Uncertainty Propagation ◽  
Calibration Procedure ◽  
Fast Response ◽  
Uncertainty Evaluation ◽  
Sensor Calibration ◽  
Pressure Probe ◽  
Aerodynamic Pressure

Abstract In the frame of a continuous improvement of the performance and accuracy in the experimental testing of turbomachines, the uncertainty analysis on measurements instrumentation and techniques is of paramount importance. For this reason, since the beginning of the experimental activities at the Laboratory of Fluid Machines (LFM) located at Politecnico di Milano (Italy), this issue has been addressed and different methodologies have been applied. This paper proposes a comparison of the results collected applying two methods for the measurement uncertainty quantification to two different aerodynamic pressure probes: sensor calibration, aerodynamic calibration and probe application are considered. The first uncertainty evaluation method is the so called “Uncertainty Propagation” method (UPM); the second is based on the “Monte Carlo” method (MCM). Two miniaturized pressure probes have been selected for this investigation: a pneumatic 5-hole probe and a spherical fast response aerodynamic pressure probe (sFRAPP), the latter applied as a virtual 4-hole probe. Since the sFRAPP is equipped with two miniaturized pressure transducers installed inside the probe head, a specific calibration procedure and a dedicated uncertainty analysis are required.

scholarly journals Uncertainty Analysis of a Test Bed for Calibrating Voltage Transformers vs. Temperature

Sensors ◽  
2019 ◽  
Vol 19 (20) ◽  
pp. 4472 ◽  
Author(s):  
Mingotti ◽  
Peretto ◽  
Tinarelli ◽  
Ghaderi
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Method ◽  
Uncertainty Analysis ◽  
Random Effects ◽  
Evaluation Method ◽  
Uncertainty Evaluation ◽  
Test Bed ◽  
Uncertainty Sources ◽  
The Monte Carlo Method

The paper addresses the evaluation of the uncertainty sources of a test bed system for calibrating voltage transformers vs. temperature. In particular, the Monte Carlo method has been applied in order to evaluate the effects of the uncertainty sources in two different conditions: by using the nominal accuracy specifications of the elements which compose the setup, or by exploiting the results of their metrological characterization. In addition, the influence of random effects on the system accuracy has been quantified and evaluated. From the results, it emerges that the choice of the uncertainty evaluation method affects the overall study. As a matter of fact, the use of a metrological characterization or of accuracy specifications provided by the manufacturers provides respectively an accuracy of 0.1 and 0.5 for the overall measurement setup.

UNCERTAINTY EVALUATION ON MULTI-HOLE AERODYNAMIC PRESSURE PROBES

2021 ◽  
pp. 1-31
Author(s):  
Andrea Notaristefano ◽  
Paolo Gaetani ◽  
Vincenzo Dossena ◽  
Alberto Fusetti
Keyword(s):  
Uncertainty Analysis ◽  
Evaluation Method ◽  
Experimental Testing ◽  
Uncertainty Propagation ◽  
Calibration Procedure ◽  
Fast Response ◽  
Uncertainty Evaluation ◽  
Sensor Calibration ◽  
Pressure Probe ◽  
Aerodynamic Pressure

Abstract In the frame of a continuous improvement of the performance and accuracy in the experimental testing of turbomachines, the uncertainty analysis on measurements instrumentation and techniques is of paramount importance. For this reason, since the beginning of the experimental activities at the Laboratory of Fluid Machines (LFM) located at Politecnico di Milano (Italy), this issue has been addressed and different methodologies have been applied. This paper proposes a comparison of the results collected applying two methods for the measurement uncertainty quantification to two different aerodynamic pressure probes: sensor calibration, aerodynamic calibration and probe application are considered. The first uncertainty evaluation method is the so called “Uncertainty Propagation” method (UPM); the second is based on the “Monte Carlo” method (MCM). Two miniaturized pressure probes have been selected for this investigation: a pneumatic 5-hole probe and a spherical fast response aerodynamic pressure probe (sFRAPP), the latter applied as a virtual 4-hole probe. Since the sFRAPP is equipped with two miniaturized pressure transducers installed inside the probe head, a specific calibration procedure and a dedicated uncertainty analysis are required.

Research on Reliability Evaluation Methods of Distribution System

2014 ◽  
Vol 672-674 ◽  
pp. 1441-1446 ◽  
Author(s):  
Yu Qiang Ou ◽  
Le Feng Cheng ◽  
Jian Zhong Wen ◽  
Xuan Yu Qiu ◽  
Tao Yu
Keyword(s):  
Distribution System ◽  
Evaluation Method ◽  
Network Reliability ◽  
Distribution Network ◽  
Reliability Evaluation ◽  
Evaluation Indexes ◽  
Specific Distribution ◽  
And Function ◽  
Meaning And Function

Research on reliability of distribution network has very important meaning and function to ensure the quality of power supply. This paper introduces some basic concepts of reliability in distribution network, including distribution network reliability definition, task and index. The classical reliability evaluation method was reviewed, and focused on specific distribution network, an example analysis was given, and specific reliability evaluation indexes were calculated. Finally, the future development of distribution network reliability evaluation was made a simple prospect.

scholarly journals Assessing the stochastic error of acoustic scattering matrices using linear methods

2018 ◽  
Vol 10 (4) ◽  
pp. 380-392 ◽  
Author(s):  
Luck Peerlings ◽  
Friedrich Bake ◽  
Susann Boij ◽  
Hans Bodén
Keyword(s):  
Uncertainty Analysis ◽  
Linear Method ◽  
Plane Waves ◽  
Acoustic Scattering ◽  
Higher Order ◽  
Condition Numbers ◽  
Matrix Perturbation ◽  
Stochastic Error ◽  
Scattering Matrices

To be able to compare the measured scattering matrices with model predictions, the quality of the measurements has to be known. Uncertainty analyses are invaluable to assess and improve the quality of measurement results in terms of accuracy and precision. Linear analyses are widespread, computationally fast and give information of the contribution of each error source to the overall measurement uncertainty; however, they cannot be applied in every situation. The purpose of this study is to determine if linear methods can be used to assess the quality of acoustic scattering matrices. The uncertainty in measured scattering matrices is assessed using a linear uncertainty analysis and the results are compared against Monte-Carlo simulations. It is shown that for plane waves, a linear uncertainty analysis, applied to the wave decomposition method, gives correct results when three conditions are satisfied. For higher order mode measurements, the number of conditions that have to be satisfied increases rapidly and the linear analysis becomes an unsuitable choice to determine the uncertainty on the scattering matrix coefficients. As the linear uncertainty analysis is most suitable for the plane wave range, an alternative linear method to assess the quality of the measurements is investigated. This method, based on matrix perturbation theory, gives qualitative information in the form of partial condition numbers and the implementation is straightforward. Using the alternative method, the measurements of higher order modes are analyzed and the observed difference in the measured reflection coefficients for different excitation conditions is explained by the disparity in modal amplitudes.

scholarly journals Comparison between ultra-high-resolution computed tomographic angiography and conventional computed tomographic angiography in the visualization of the subcallosal artery

2021 ◽  
Vol 12 ◽  
pp. 528
Author(s):  
Yoshimichi Sato ◽  
Toshiki Endo ◽  
Shingo Kayano ◽  
Hitoshi Nemoto ◽  
Kazuki Shimada ◽  
...  
Keyword(s):  
High Resolution ◽  
Evaluation Method ◽  
Computed Tomographic Angiography ◽  
Anterior Communicating Artery ◽  
Exact Test ◽  
Computed Tomographic ◽  
Small X ◽  
Tomographic Angiography ◽  
Better Than

Background: The subcallosal artery (ScA) is a single dominant artery arising from the anterior communicating artery. Its injury causes amnesia and cognitive disturbance. The conventional computed tomographic angiography (C-CTA) is a common evaluation method of the intracranial artery. However, to image tinny perforating arteries such as the ScA is technically demanding for C-CTA. The purpose of this study is to investigate whether the ultra-high-resolution CTA (UHR-CTA) could image the ScA better than C-CTA. UHR-CTA became available in clinical practice in 2017. Its novel features are the improvement of the detector system and a small X-ray focus. Methods: Between April 2019 and May 2020, 77 and 49 patients who underwent intracranial UHR-CTA and C-CTA, respectively, were enrolled in this study. Two board-certified neurosurgeons participated as observers to identify the ScA based on UHR-CTA and C-CTA images. Results: UHR-CTA and C-CTA detected the ScA in 56–58% and 30–40% of the patients, respectively. In visualization of the ScA, UHR-CTA was better than C-CTA (P < 0.05, Fisher’s exact test). Between the two observers, the Cohen’s kappa coefficient was 0.77 for UHR-CTA and 0.78 for C-CTA. Conclusions: UHR-CTA is a simple and accessible method to evaluate intracranial vasculature. Visualization of the ScA with UHR-CTA was better than that with C-CTA. The high quality of UHR-CTA could provide useful information in the neurosurgery field.

scholarly journals Application of Analytical Hierarchy Process in Teaching Quality Analysis of English Writing

2020 ◽  
Vol 15 (14) ◽  
pp. 137
Author(s):  
Xiaoqin Zhang ◽  
Shengxin Wang ◽  
Yanling Cao ◽  
Guangqi Chen
Keyword(s):  
Analytical Hierarchy Process ◽  
Evaluation System ◽  
Evaluation Method ◽  
Evaluation Model ◽  
Teaching Quality ◽  
Quality Analysis ◽  
English Writing ◽  
Evaluation Systems ◽  
Hierarchy Process

There are two major problems in the evaluation of the teaching quality of English writing: the weak logic of the evaluation system and the low reliability of the evaluation model. To solve the problems, this paper put forward an evaluation method for the teaching quality of English writing based on the analytical hierarchy process (AHP). Firstly, the authors reviewed the current evaluation methods for the teaching quality of English writing. Next, hierarchical evaluation systems were established for the teaching quality of English writing from the perspectives of teachers and students, respectively. After that, the AHP method and the grey theory were introduced to set up an evaluation model for the teaching quality of English writing. Finally, several strategies were presented to improve the teaching quality of English writing. The proposed evaluation systems and model enriched the theories on teaching quality evaluation of English writing, and promoted the teaching quality of English writing.

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