Maximum Measurement Uncertainty Research Articles

A novel Zende’s-TOPSIS method towards estimation of measurement uncertainty in hole diameters

The ‘Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS)’ is one of the best methods for ‘Multi-Criteria Decision-Making’ and ‘Multi-Objective Optimization’. The traditional TOPSIS method determines the best alternative under fixed conditions. However, it cannot determine the best upper limit and lowest limit values. This work explains the detailed methodology of the newly developed Zende’s-TOPSIS method which was used to estimate the measurement uncertainty in hole diameters. Four identical holes and one center hole in an industrial component were measured to investigate measurement uncertainty. According to the experimental results, Zende’s-TOPSIS method performed better than the traditional TOPSIS method. The percentage improvement in the Zende’s-TOPSIS method over the traditional TOPSIS method ranges from 0.0209% to 0.3053%. Using Zende’s-TOPSIS method, the percentage maximum measurement uncertainty for four identical holes varies from 0.8067% to 1.0222%, whereas for the center hole, it varies from 0.5261% to 0.5576%. Similarly, the percentage minimum measurement uncertainty for four identical holes varies from 0.3839% to 0.6406%, whereas for the center hole, it varies from 0.4014% to 0.4041%. The proposed method is also capable of estimating the machined tolerances of the component, which ranges from 18.0772 mm to 18.1708 mm for four identical holes and 49.2215 mm to 49.2572 mm for the center hole. The proposed method can solve various ‘Multi-Objective Optimization’ problems.

Assessment of glycerol in biodiesel using an ultrasonic measurement method

Biodiesel is a renewable fuel, biodegradable and alternative to diesel oil consisting chemically of fatty acid alkyl esters and obtained by the transesterification reaction. After transesterification, undesirable components may remain in biodiesel. The presence of these components negatively influences the properties and performance of biodiesel. This research aims to evaluate biodiesel quality, using the quantitative ultrasound technique to determine the presence of the contaminant glycerol in biodiesel samples. The blends used in this study consisted of biodiesel and glycerol varying from 0 % to 0.5 % of glycerol by mass. The measurement uncertainty was evaluated according to the Guide to the Expression of Uncertainty in Measurement. The speed of sound in biodiesel/glycerol blends was measured by the pulse-echo technique (@ 5 MHz) and was considered equivalent for the different concentrations studied. The maximum measurement uncertainty obtained was 2.2 m·s−1 (0.16 %).

Line positions and effective line strengths of trans-HONO near 1280 cm−1

The measurement of the line positions and effective line strengths of the ν3 fundamental band of trans-nitrous acid (trans-HONO) near 1280 cm−1 (7.8 µm) by tunable laser absorption spectroscopy (TLAS) utilizing a room temperature continuous-wave quantum cascade laser (cw-QCL) was reported. The effective line strengths of 30 well-resolved trans-HONO absorption lines in the range of 1279.8–1282.2 cm−1 were determined using the HONO line strength at 1280.3841 cm−1 as a scale. The maximum measurement uncertainty of 7.64% in the line strengths is mainly determined by the uncertainty of the referenced line strength, while the measurement precision of the line positions is better than 5.56 * 10−3 cm−1. The line positions and strengths of the trans-HONO absorption lines obtained in this work provide a reference for continuous gas monitoring and analysis of the sources and sinks of atmospheric HONO.

Alternative Approach Leading to Reduction in Measurement Instrument Uncertainty of EMI Measurement

Abstract Even in the field of electromagnetic compatibility, low measurement uncertainty means high measurement quality. Although there are standardized procedures for obtaining the uncertainty of such a measurement, which facilitate uncertainty estimation, modern approaches show further reduction possibilities. The paper presents an alternative approach to reducing measurement instrument uncertainty in the case of electromagnetic interference measurement based on many years of our experience and a large number of measurements in this field. In the paper, two different methods of uncertainty reduction are described. The first method is based on a detailed analysis of the sources of uncertainty and the subsequent division of the analyzed frequency band into more subranges. Another method uses the choice of the antenna factor, which also contains information about the test site where the measurement is carried out. In this way, despite a lengthy analysis, it is relatively easy to achieve a measurement instrument uncertainty that is below the maximum measurement uncertainty given by the CISPR standard.

Uji Kalibrasi Alat Ukur Massa pada Neraca Analitik Menggunakan Metode Perbandingan Langsung

The research describes the effect of weights on the calibration results of an analytical balance. This study aims to obtain the uncertainty value of the analytical balance test results by comparison with the standard E2 class weights. The study results can be used to determine the feasibility of the measuring instrument tested through the analysis of the performance value of the scales based on the Limit of Performance (LOP) parameter. The method used is a direct comparison method with E2 class weights. The calibration process carried out in this method includes the measurement of repeatability of readings, deviations from the nominal value indication, the effect of loading not at the centre of the pan , and hysteresis. The data analysis includes standard deviation values, minimum correction values, hysteresis, uncertainty, and LOP. The calibration results show that the reading power of the standard deviation of the load at ½ maximum capacity and full maximum capacity is 0.0042 grams. Deviations at measuring points 20, 40, 60, 80, 100, 120, 140, 160, 180, and 200 grams have a maximum correction value of 0.04995 grams with a maximum measurement uncertainty of 0.006378585 grams and a value of k=2.0 at 95% confidence level. In the performance table of the scales based on the LOP value, it is known that the performance of the scales is in the poor category, and it is more advisable to repair the tool.

Use neural network in photoacoustic measurement of thermoelastic properties of aluminum foil

The objective of this paper is to present methodology of the precise and reliable determination of thermal diffusivity and linear coefficient of thermal expansion of the photoacoustic signal recorded (obtained) using open photoacoustic cell where thickness of the sample served as a control parameter. The methodology was based on the application of neural networks that were trained on numerical experiments and optimized by adding Gaussian noise to the training base that corresponded in percentage to maximum measurement uncertainty. By comparing the predictions of the neural network with theoretical fitting curve for experimental results for the aluminum sample that was 197 μm thick, it was shown that the proposed methodology achieves high precision in the determination of thermoelastic and geometrical properties of the sample.

Dosimetric performance of a multipoint plastic scintillator dosimeter as a tool for real-time source tracking in high dose rate Ir brachytherapy.

This study aims to present the performance of a multipoint plastic scintillation detector (mPSD) as a tool for real-time dose measurements (covering three orders of magnitude in dose rate), source-position triangulation, and dwell time assessment in high dose rate (HDR) brachytherapy. A previously characterized and optimized three-point sensor system was used for HDR brachytherapy measurements. The detector was composed of three scintillators: BCF60, BCF12, and BCF10. Scintillation light was transmitted through a single 1-mm-diameter clear optical fiber and read by a compact assembly of photomultiplier tubes (PMTs). Each component was numerically optimized to allow for signal deconvolution using a multispectral approach, taking care of the Cerenkov stem effect as well as extracting the dose from each scintillator. The PMTs were read simultaneously using a data acquisition board at a rate of 100KHz and controlled with in-house software based on Python. An source (Flexitron, Elekta-Brachy) was remotely controlled and sent to various positions in a in-house PMMA holder, ensuring 0.1mm positional accuracy. Dose measurements covering a range of 10cm of source movement were carried out according to TG-43 U1 recommendations. Water measurements were performed in order to: (a) characterize the system's response in terms of angular dependence; (b) obtain the relative contribution of positioning and measurement uncertainties to the total system uncertainty; (c) assess the system's temporal resolution; and (d) track the source position in real time. The triangulation principle was applied to report the source position in three-dimensional space. As expected, the positioning uncertainty dominated close to the source, whereas the measurement uncertainty dominated at larger distances. A maximum measurement uncertainty of 17 % was observed for the BCF60 scintillator at 10cm from the source. Based on the uncertainty chain, the best compromises between positioning and measurement uncertainties were reached at 17.2, 17.4, and 17.5mm for the BCF10, BCF12, and BCF60 scintillators, respectively, which also corresponded to the recommended optimal distances to the source for calibration purposes. The detector further exhibited no angular dependence. All dose values were found to be within 2% of the dose value at . In the experiments performed for source-position determination, the system provided an average location with a standard deviation under 1.7mm. The maximum observed differences between measured and expected values were 1.82 and 1.8mm in the x- and z-directions, respectively. Deviations between the mPSD measurements and expected TG-43 values were below 5% in all the explored measurement conditions. With regard to dwell time measurement accuracy, the maximum deviation observed at all distances was 0.56±0.25s, with a weighted average of the three scintillators below 0.33±0.37 s at all distances covered in this study. Real-time HDR brachytherapy measurements were performed with an optimized mPSD system. The performance of the system demonstrated that it could be used for simultaneous, in vivo, real-time reporting of dose, dwell time, and source position during HDR brachytherapy.

Direct measurement of 1-mN-class thrust and 100-s-class specific impulse for a CubeSat propulsion system.

This paper presents the development of a thrust stand to enable direct measurement of thrust and specific impulse for a CubeSat propulsion system during firing. The thrust stand is an inverted pendulum and incorporates a mass balance for direct in situ mass measurement. The proposed calibration procedure allows precise performance characterization and achieves a resolution of 80 μN thrust and 0.01 g mass loss, by taking into account the drift of the thrust-stand zero caused by propellant consumption. The performance of a water micro-resistojet propulsion system for CubeSats was directly characterized as a proof of concept of the thrust stand. Continuous profiles of thrust, specific impulse, and mass consumption were acquired under various conditions in a single firing test. A thrust from 1 mN to 10 mN and a specific impulse from 45 s to 100 s with a maximum measurement uncertainty of ±15.3% were measured for the throat Reynolds number in the range 100-400.

Contactless direct torque measurement system for a single cylinder engine transient test cell

This paper describes the design and implementation of a low cost, contacless, reliable and sensitive direct torque measurement system applied to small single cylinder engine transient test cell. The experimental set-up consists of a three-phase induction machine, used as a transient a.c. dynamometer, and non-regenerative frequency inverter connected to an internal combustion engine. Coupling the engine to the dynamometer is by a low stiffness PA-6 nylon shaft with magnetic pickups at its ends. The sensors phase are zero when torque in PA-6 nylon shaft is null, adjusted in static conditions and engine/dynamometer turned off. Contactless torque measurement occurs by magnetic pickup phase difference during PA-6 nylon shaft torsion promoted by engine in operation. Engine speed is measurement by frequency of magnetic pickup signal. PA-6 nylon shaft torsion promotes a misalignment between sensors phase, proportional to torque application in both direction.The electronic capture unit using pulse train rising edge detection measures this phase change (time shift) in pulses. An embedded microcontroller development kit acquires the time-shifted pulses. This board has circuits for A/D signal conditioning, pulse width modulate channels, and a specific circuit for magnetic pickups signals conditioning, which can measure less then 0.09 Nm resolution, taking 96 time-shifts values. The design and implementation of all embedded electronics and data acquisition system follows electromagnetic compatibility premises, which have resulted in an adequate signal-to-noise ratio so that common and differential mode noises have not edges with amplitude approximately equal to the output magnetic sensors signals. The maximum measurement uncertainty associated with the contacless direct torque measurement system were calculated at ±0.54% to 99% confidence interval.The performance is presented under different load conditions, defined by engine throttle position and the results are compared with the engine datasheet performance curves.

Practical methodology for in situ measurement of micro flow rates using laser diode absorption sensors

A laser diode-based flowmeter based on the infrared absorption method that can measure in situ micro flow rates from 0.2 to 20 ml h−1 was developed. A 1450 nm laser absorbed in water was irradiated to form a heated spot at 0 mm, and the temperature was measured upstream and downstream of the heated spot. The flow rate was measured by the temperature difference obtained by two diode lasers and photodetectors upstream and downstream of the heated spot. We measured the temperature profile of the flow rate by changing the temperature measurement position and the heating laser energy upstream and downstream of the heated spot, and compared the measurements with the simulation results. As the flow rate increased, the temperature profile shifted downstream, and the measured temperature upstream and downstream were analyzed according to the flow rate. The flow measurement range was adjusted according to the temperature measurement position. Increasing the energy of the heating laser also improved the measurement accuracy in the lower flow range. The developed flowmeter was calibrated by the gravimetric method, and the deviation and measurement uncertainty according to the flow rate were obtained. The maximum measurement uncertainty was 6.8% at a 1 ml h−1 flow rate, and the minimum measurement uncertainty was 1.78% at 8 ml h−1. Thus, it was confirmed that the flow rate can be measured through the temperature difference gauged using a simple diode laser set. Using the laser diode-based flowmeter developed in this study, one can measure the flow rate in situ without injecting contaminants, such as particles, for measurements without cutting the piping. In addition, it can be manufactured in a miniaturized form at a low cost, and thus, it can be used for multi-drug infusion analysis, semiconductor process monitoring, etc.

A novel method for testing accelerometer transverse sensitivity.

This paper presents a flexure-based compliant mechanism for testing accelerometer transverse sensitivity. The definition of transverse sensitivity is first described. Subsequently, the detailed structure of the developed mechanism is introduced. The principle of this method and the corresponding theoretical model are analyzed. Based on the principle, a prototype is manufactured and an experimental platform is set up. The circular trajectory tests are carried out to verify the feasibility of this method. It shows that the precision of the circular trajectory can be guaranteed. Finally, a three-axis piezoelectric accelerometer is tested. The maximum transverse sensitivity is below 5%, and its maximum measurement uncertainty is 0.15%, while the maximum measurement uncertainty of the corresponding direction angle is 0.79°. It demonstrates that the proposed method is reasonable and accurate.

Acoustic and thermodynamic properties of a binary liquid cyclohexane + n-hexadecane mixture

The speed of sound in a binary liquid cyclohexane + n-hexadecane mixture is investigated by direct measurement of the pulse propagation time at ranges of temperature of 298–433 K and pressure of 0.1–100.1 MPa. The maximum measurement uncertainty is 0.1%. The density, isobaric expansion coefficient, isobaric and isochoric heat capacity, and isothermal compressibility of the mixture of three compositions are determined at 298–348 K and 0.1–80 MPa based on the data on speed of sound. The excess molar volume and coefficients of the Tait equation are calculated in the stated ranges. Thermodynamic properties of the mixture are presented in the tabular form.

Effective line intensity measurements of trans-nitrous acid (HONO) of the ν1 band near 3600 cm−1 using laser difference-frequency spectrometer

We report on the measurements of the effective line intensities of the ν1 fundamental band of trans-nitrous acid (trans-HONO) in the infrared near 3600cm−1 (2.78µm). A home-made widely tunable laser spectrometer based on difference-frequency generation (DFG) was used for this study. The strengths of 28 well-resolved absorption lines of the ν1 band were determined by scaling their absorption intensities to the well referenced absorption line intensity of the ν3 band of trans-HONO around 1250cm−1 recorded simultaneously with the help of a DFB quantum cascade laser (QCL) spectrometer. The maximum measurement uncertainty of 12% in the line intensities is mainly determined by the uncertainty announced in the referenced line intensities, while the measurement precision in frequency positions of the absorption lines is better than 6×10−4cm−1. The cross-measurement carried out in the present work allows one to perform intensity calibration using well referenced line parameters.

Bilateral Comparison of Blackbodies for Clinical Infrared Ear Thermometers between NIMT and NMIJ

This article describes the results of the bilateral comparison of blackbodies for infrared ear thermometers (IRETs) between the National Institute of Metrology (Thailand), NIMT, and the National Metrology Institute of Japan (NMIJ). The purpose of this comparison was to ensure consistency of the national radiance temperature scales for IRETs maintained by NIMT and NMIJ. Results of the measurements indicate differences in radiance temperature within 10 mK with a maximum measurement uncertainty of 64 mK. The equivalence of the radiance temperature scales realized by both NIMT and NMIJ in the range of 35 \(^{\circ }\)C to 42 \(^{\circ }\)C for IRET calibration is indicated. The results of this bilateral comparison can be used in terms of quality assurance and validation of calibration.

TRACKING OF HEAD POSITION RELATIVE TO THE SCREEN USING HEAD MOUNTED CAMERA / GALVOS POZICIJOS NUSTATYMAS EKRANO ATŽVILGIU NAUDOJANT ANT GALVOS PRITVIRTINTĄ KAMERĄ

In this paper head position locating systems were analyzed. There were reviewed scientific articles with different proposed methods. The chosen system is with the camera located on the user head. The main parameters of the head positioning systems were analyzed. The procedure laid down in what order parameters are found. The diagram of the system and detail block diagram of the algorithm were provided. Realization of the algorithm used: edge detection method (Sobel), the adjustment algorithm (Subpixel). System is realized in Matlab and C# environment. Determine the optimal parameters for the algorithm execution. Execution of the algorithm in Matlab environment is 1.2 s and C # environment – 126 ms. During the examination of the longest executing algorithm segment, it was found that image filtering is carried out in 107 ms. It is noted that the uncertainty of the algorithm can be divided into static and measurement. The maximum static uncertainty while measuring head position parameters is 1.63 mm and orientation parameters – 0.16°. The maximum measurement uncertainty while measuring head position parameters is 4 mm and orientation parameters – 0.11°. Santrauka Nagrinėjamos galvos padėties pozicionavimo sistemos. Apžvelgti moksliniai straipsniai, kuriuose pateikiami įvairūs siūlomi metodai. Pasirinkta sistema, kai kamera pritvirtinama vartotojui ant galvos. Išskirti pagrindiniai galvos padėties nustatymo parametrai, nustatytas parametrų suradimo eiliškumas, pateikta sistemos schema ir detali algoritmo blokinė schema. Algoritmui įgyvendinti taikyti briaunų radimo (Sobel) ir algoritmo tikslinimo (Subpixel) metodai. Sistema įgyvendinta Matlab ir C# aplinkose. Nustatyti optimalūs algoritmo vykdymo parametrai. Naudojamo kompiuterio procesorius Intel Pentium dual core T4500 – 2,3 GHz. Vidutinis algoritmo veikimo laikas Matlab aplinkoje yra 1,2 s, o C# aplinkoje – 126 ms. Ištyrus algoritmo segmentų vykdymo laiką, pastebėta, kad ilgiausiai vykdomas vaizdo filtravimas – 107 ms. Parodyta, kad algoritmo neapibrėžtis galima suskirstyti į statines ir matavimo neapibrėžtis. Maksimali statinė neapibrėžtis, matuojant galvos pozicijos padėtį, yra 1,63 mm, matuojant orientacijos parametrus – 0,16°. Maksimali matavimo neapibrėžtis yra 4,0 mm, matuojant galvos padėties parametrus, ir 0,11° – orientacijos parametrus.

Using target measurement uncertainty to determine fitness for purpose

The methods an analytical laboratory uses must be validated to be fit for purpose. The fitness for purpose of a quantitative method used to determine the concentration of a substance when assessing compliance to requirements can be described by the maximum measurement uncertainty. This is called the target measurement uncertainty. Acceptance criteria for precision and bias in the method validation are then established in terms of the target measurement uncertainty. The target measurement uncertainty can be decided by following a process which involves determining the required concentration range of the measurand; determining the acceptable level of risks of incorrect decisions of compliance; developing a suitable decision rule, with guard bands if appropriate; using the probability of making an incorrect decision of compliance based on the decision rule; and assessing the impact of bias. A key participant in this process is the end user of the data, the laboratory customer. This paper presents the concepts concerning target measurement uncertainty introduced in recently published international guidelines to the practicing analytical chemist who is not generally familiar with these concepts. Three examples are used to illustrate the process.