VISCOMETRY OF NANODISPERSE MAGNETIC LIQUIDS AND LUBRICATING OILS. 2. METROLOGICAL ANALYSIS OF A DEVICE FOR RHEOLOGICAL STUDIES OF MAGNETIC NANODISPERSE LIQUID MEDIA

Проведен анализ основных источников методических погрешностей магнитного ротационного вискозиметра, позволивший усовершенствовать конструкцию и исключить критические режимы исследований. Теоретическая оценка систематической погрешности прибора показала, что значение относительной ошибки измерений можно довести до значения менее 1%. Наибольший вклад в систематическую погрешность прибора вносит нестабильность температурного режима исследуемой наножидкости и неточность определения высоты слоя жидкости, контактирующего с измерительным цилиндром. Измерение вязкости эталонных жидкостей на магнитном вискозиметре показало, что экспериментальные значения незначительно, примерно на 0,9% завышены. Тарировка прибора на различных эталонных жидкостях позволила снизить суммарную ошибку измерений до десятых долей процента. Магнитный ротационный вискозиметр может найти применение при нестандартных научных исследованиях структуры и реологических характеристик наножидкостей, для оперативного контроля процессов синтеза магнитных жидкостей и аттестации магнитных наножидкостей, предназначенных для технического применения. An analysis is carried out of the main sources of methodological errors of the magnetic rotary viscometer. The analysis allowed to improve design and to eliminate critical modes of the research. Theoretical evaluations of the systematic error of the device showed that the value of the relative measurement error can be brought to a value of less than 1%. The greatest contribution to the systematic error of the device is made by the instability of the temperature regime of the nanofluid under study and by the inaccuracy of determining the height of the liquid layer in contact with the measuring cylinder. The measurement of the viscosity of the reference liquids on the magnetic viscometer showed that experimental values are slightly, by about 0.9% overestimated. Calibration of the device on various reference liquids allowed reducing the total measurement error down to tenths of a percent. The magnetic rotary viscometer can be used in non-standard scientific studies of the structure and rheological characteristics of nanofluids, for operational control of the processes of synthesis of magnetic liquids and certification of magnetic nanofluids intended for technical use.

Methods of Precise Distance Measurements for Laser Rangefinders with Digital Acquisition of Signals

The article presents methods of long range distance measurements using pulsed lasers and the Time of Flight principle. Various algorithms of laser distance measurements with digital acquisition of echo pulses (acquisition of a signal’s full waveform) are presented. The main focus of work is concentrated on the method of distance measurements developed by the authors. With this method, during laboratory trials, a total measurement error of one centimeter was achieved using a 905 nm pulsed laser diode and pulse width of 39 ns. The maximum range of measurements with such high precision is limited only by a signal to noise ratio, duration of measurements and atmospheric conditions. All algorithms were implemented in a laser rangefinder module developed by the authors. Simulations and laboratory experiments were conducted and algorithm’s accuracy and precision were tested for various SNR conditions and changing distances.

An Improved STEM/EDX Quantitative Method for Dopant Profiling at the Nanoscale

In this paper, an improved quantification technique for STEM/EDX measurements of 1D dopant profiles based on the Cliff-Lorimer equation is presented. The technique uses an iterative absorption correction procedure based on density models correlating the local mass density and composition of the specimen. Moreover, a calibration and error estimation procedure based on linear regression and error propagation is proposed in order to estimate the total measurement error in the dopant density. The proposed approach is applied to the measurement of the As profile in a nanodevice test structure. For the calibration, two crystalline Si specimens implanted with different As doses have been used, and the calibration of the Cliff-Lorimer coefficients has been carried out using Rutherford Back Scattering measurements. The As profile measurement has been carried out on an FinFET test structure, showing that quantitative results can be obtained in the nanometer scale and for dopant atomic densities lower than 1%. Using the proposed approach, the measurement error and detection limit for our experimental setup are calculated and the possibility to improve this limit by increasing the observation time is discussed.

Simultaneous Extraction and Determination of Preservatives and Antioxidants in Juice Samples by an Optimized Microextraction Method Using Central Composite Design and Validated with Accuracy Profile

Background: Food additives are widely used in industries. Overall, these additives have a beneficial role, but if their concentration exceeds certain limits, they may have an adverse effect on human health. Objective: This study outlines the determination of benzoic acid (BA), sorbic acid (SA), butylated hydroxyanisole (BHA), and butylated hydroxytoluene (BHT) in juices using dispersive liquid–liquid microextraction and HPLC–diode-array detection. Methods: Different parameters that significantly affect the extraction efficiency were optimized. The disperser and extraction solvents were acetone and chloroform, respectively. The other parameters were selected and optimized using two-level (2k) factorial and central composite designs, respectively. A full method validation using an accuracy profile for the total measurement error was carried out. Results: The optimized conditions were 625 μL acetone, 350 μL chloroform, 0.85 g NaCl, and pH 2. The validated method demonstrated good linearity with R2 ≥ 0.99 and good precision with the RSD of repeatability and intermediate precision at 1.97–10.7% and 2.31–11.9%, respectively. The relative recoveries were 96.2–105.4%, and the LODs were around 0.03 μg/mL for all compounds. The analysis of 41 samples revealed that BA and SA were quantified in 25 and 20 samples, respectively. BHA and BHT were not detected. Conclusions: The proposed methodology is an appropriate tool to determine important food additives in juices to ensure their compliance with the food additives legislation. Highlights: The work has demonstrated that the method can be successfully used in the simultaneous determination of four food additives in fruit juices.

Tilt error in cryospheric surface radiation measurements at high latitudes: a model study

We have evaluated the magnitude and makeup of error in cryospheric radiation observations due to small sensor misalignment in in situ measurements of solar irradiance. This error is examined through simulation of diffuse and direct irradiance arriving at a detector with a cosine-response fore optic. Emphasis is placed on assessing total error over the solar shortwave spectrum from 250 to 4500 nm, as well as supporting investigation over other relevant shortwave spectral ranges. The total measurement error introduced by sensor tilt is dominated by the direct component. For a typical high-latitude albedo measurement with a solar zenith angle of 60°, a sensor tilted by 1, 3, and 5° can, respectively introduce up to 2.7, 8.1, and 13.5 % error into the measured irradiance and similar errors in the derived albedo. Depending on the daily range of solar azimuth and zenith angles, significant measurement error can persist also in integrated daily irradiance and albedo. Simulations including a cloud layer demonstrate decreasing tilt error with increasing cloud optical depth.

Tilt error in cryospheric surface radiation measurements at high latitudes: a model study

We have evaluated the magnitude and makeup of error in cryospheric radiation observations due to small sensor misalignment in in-situ measurements of solar irradiance. This error is examined through simulation of diffuse and direct irradiance arriving at a detector with a cosine-response foreoptic. Emphasis is placed on assessing total error over the solar shortwave spectrum from 250 to 4500 nm, as well as supporting investigation over other relevant shortwave spectral ranges. The total measurement error introduced by sensor tilt is dominated by the direct component. For a typical high latitude albedo measurement with a solar zenith angle of 60°, a sensor tilted by 1, 3, and 5° can respectively introduce up to 2.6, 7.7, and 12.8 % error into the measured irradiance and similar errors in the derived albedo. Depending on the daily range of solar azimuth and zenith angles, significant measurement error can persist also in integrated daily irradiance and albedo.

Metrological assurance of magnetic suspension concentration measurements during non-destructive testing of aircraft

The results of metrological certification of domestic and foreign measurement methods by indirect method of magnetic suspension concentration in technological processes of nondestructive testing of aircraft in air transport and aerospace industry are presented. The appraisal results confirm the compliance of measurement procedures with the requirements of GOST R 8.563 and OST 54-3-154.82. The components of the total measurement error were identified and investigated, the numerical values of the total measurement errors of the magnetic suspension concentration were established.

Determination of Tin and Nickel Content in Pyrophosphate Tin-Nickel Alloy Plating Bath

Tin and nickel ions are in stable complexing form in Pyrophosphate tin-nickel alloy plating bath, this paper uses back-titration of Zn2+ standard solution to determine total amount of tin and nickel ions, and spectrophotometry to determine content of nickel ions in the bath to study interference and elimination methods of co-existing components. The results show that: eliminate the interference of pyrophosphate by heating the solution to hydrolyse and mask Sn4+ and Fe3+ effectively with triethanolamine, the total measurement error is about 0.91%, standard deviation is 0.0141; The recovery of determination for nickel ion content is 99.13%, and standard deviation is 0.0180; The method i-s simple, fast and is able to meet the analytical requirements for controlling the plating quality.