Accurate Measurement Results Research Articles

Self-Calibrated Measurement Method Based on Structured Illumination Microscopy

Structured illumination microscopy (SIM) has attracted many attentions due to high-precision, high-efficiency and strong adaptability. In most SIM, two essential parameters need to be accurately obtained to restore the 3D shape of the object which are the focus position of each pixel z <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">max</sub> and the scan step Δz. For years, researchers have constantly improving the structure of SIM system to obtain more accurate z <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">max</sub> to realize optimized measurement results. Meanwhile, the preset value of Δz is directly substituted into calculation. However, the actual value of Δz is very likely inconsistent with the preset value due to various factors in practical such as nonlinear motion of scan actuator, which will introduce great error into the measurement result. In this letter, a self-calibrated measurement method is proposed to resolve this problem. As we know, the full width at half maximum (FWHM) of the modulation curve is uniquely determined when the optical measurement system is determined. In this letter, a self-calibrated measurement method based on SIM (SC-SIM) is proposed and the determined FWHM is utilized to calculate the actual value of Δz to realize more accurate and reliable measurement result. Simulation and experiment are carried out to demonstrate the feasibility of the proposed method.

Study on the temperature characteristics of fast capacitance in patch clamp experiments

Patch clamp is a technique that can measure weak current in the level of picoampere (pA). It has been widely used for cellular electrophysiological recording in fundamental medical researches, such as membrane potential and ion channel currents recording, etc. In order to obtain accurate measurement results, both the resistance and capacitance of the pipette are required to be compensated. Capacitance compensations are composed of slow and fast capacitance compensation. The slow compensation is determined by the lipid bilayer of cell membrane, and its magnitude usually ranges from a few picofarads (pF) to a few microfarads (μF), depending on the cell size. The fast capacitance is formed by the distributed capacitance of the glass pipette, wires and solution, mostly ranging in a few picofarads. After the pipette sucks the cells in the solution, the positions of the glass pipette and wire have been determined, and only taking once compensation for slow and fast capacitance will meet the recording requirements. However, when the study needs to deal with the temperature characteristics, it is still necessary to make a recognition on the temperature characteristic of the capacitance. We found that the time constant of fast capacitance discharge changed with increasing temperature of bath solution when we studied the photothermal effect on cell membrane by patch clamp. Based on this phenomenon, we proposed an equivalent circuit to calculate the temperature-dependent parameters. Experimental results showed that the fast capacitance increased in a positive rate of 0.04 pF/℃, while the pipette resistance decreased. The fine data analysis demonstrated that the temperature rises of bath solution determined the kinetics of the fast capacitance mainly by changing the inner solution resistance of the glass pipette. This result will provide a good reference for the fine temperature characteristic study related to cellular electrophysiology based on patch clamp technique.

Defocused projection model for phase-shifting profilometry with a large depth range.

Phase-shifting 3D profilometry is widely combined with defocused projection, but the accuracy of defocused projection could be far below expectations especially in the case of large depth range measurement. In this paper, a new defocus-induced error related to the shape of the measured object is pinpointed and a novel defocused projection model is established to cope with such a error to improve the accuracy of defocusing phase-shifting profilometry. Supplemented with a specialized calibration and reconstruction procedure, the phase is well corrected to obtain accurate measurement results. Furthermore, the impact of the defocus-induced error is analyzed through simulations, and the feasibility of our method is verified by experiments. Faced with issues involving a large measurement range, the proposed method is expected to give a competitive performance.

The measurement of δ13C in respiratory gases based on incoherent broadband cavity enhanced absorption spectroscopy

The change of stable isotope ratio of carbon dioxide (δ13CO2) in respiratory gases of patients before and after taking medicine can be used to judge whether Helicobacter pylori exists in patients’ intestines and stomach. The 4.3 μm band of blackbody radiation source and infrared dual path structure are selected for measurement, the incoherent broadband cavity enhanced absorption spectroscopy (IBBCEAS) technology was used to change the structure of the light path on one side of 13CO2 to make sure that the absorption intensity of 13CO2 and 12CO2 was in the same order of magnitude. The influence of different types of optical cavity, coating method of lens and reflectivity of mirror on effective optical path were compared in this article and the effective optical path length was the largest when the semi-stable cavity with 90% reflectivity and Ge coating material was used. The standard deviation of the measurement results was 0.191‰, which met the requirements of the precision and accuracy of the measurement index in medical detection. The system had the advantages of high precision, small volume, and accurate measurement results, which is of great significance for medical auxiliary detection.

The Virtual Lock-in Amplifiers - Accuracy of Measurement Results in Light Transmission Experiments

This research focuses on the analysis of the measurement result of the virtual lock-in amplifier (virtual-LIA) in the light transmission experiment as the trial step of developing the virtual-LIA. The virtual-LIA used in this research is designed by using the Vernier sensor DAQ as the data acquisition and the LabVIEW as the programming media. The design of virtual-LIA is based on the mathematical operations of LIA. The type of virtual-LIA is a single phase with the capabilities to process the external reference signal. Light transmission experiments are carried out using formazin polymer suspension with turbidity level of 3000 NTU, 3500 NTU, and 4000 NTU as the medium in which light is passed. The accuracy of the measurement results is known by comparing the results of virtual-LIA with real-LIA SR510. The experiments are also carried out in bright and darkroom conditions to determine the ability of virtual-LIA in reducing noise signals. Based on the experiment, the results obtained that the measurement accuracy of the virtual-LIA developed is above 94% compared to the LIA SR510. Virtual-LIA could measure small signals with and without noise with the average percentage of differences measured between dark and bright conditions is 0.54%.

Research on Golay-coded excitation in real-time imaging of high frequency ultrasound biomicroscopy

High frequency ultrasonic imaging provides clinicians with high-resolution diagnostic images and more accurate measurement results. The technique is now widely used in ophthalmology, dermatology, and small animal imaging. However, since ultrasonic attenuation in tissue increases rapidly with increasing frequency, the depth of detection of high frequency ultrasound in tissue is limited to a few millimeters. In this paper, a novel method of using Golay-coded excitation as a replacement for conventional single-pulse excitation in high frequency ultrasound biomicroscopy was proposed, and real-time imaging was realized. While maintaining the transmission voltage and image resolution unchanged, the detection depth can be effectively improved. The ultrasonic transmission frequency is 30 MHz and the transmission voltage is ± 60 V p-p. In this study, 4-bit, 8-bit, and 16-bit coding sequences and decoding compression were used. To verify the effectiveness of the coding sequence in real-time imaging of ultrasound biomicroscopy, we designed a 10-μm diameter line target echo experiment, an ultrasound phantom experiment, and an in vitro porcine eye experiment. The experimental results show that the code/decode method of signal processing can not only maintain a resolution consistent with that of single-pulse transmission, but can also improve the detection depth and signal-to-noise ratio.

Optimizing modified triaxial testing for small strain zone using local displacement transducers and bender element for cement-treated soft soil

The settlement behavior is a common problem on the railway structure that can be optimized by applying cement-treated soil as ground restoration. However, the application of a high cement mixing content needs a proper estimation that can be achieved by adjusting the element testing. The strain measurement devices can estimate the deformation characteristics, such as secant modulus, Poisson ratio, and shear modulus that can describe the settlement behavior and stiffness of cement-treated soil. This research is focused on a static analysis of triaxial consolidated undrained (CU¯) testing that is improved by the axial and radial local displacement transducer (LDT) and bender element to increase the accuracy of measurement results. Furthermore, the secant modulus and shear modulus is more accurate when the combination of radial and axial LDT is used due to a small strain range. Lastly, the shear modulus measurement is improved by using a filler in the cement-treated soil for the bender element test. To conclude, this system of testing for the static condition can be utilized for the dynamic condition, because the measurement shows a reliable result for a small strain range which is the parameter of the dynamics condition.

Separation and analysis method of overlapping absorption spectra with cross interference in gas mixture measurement

The interference between overlapping gas absorption lines often occurs in the measurement of multi-component gas mixture with using tunable diode laser absorption spectroscopy (TDLAS). This is also the main problem of the technology in some applications. For instance, in the early application of multi-component gas mixture measurement in coal mines, we found that the absorption lines of carbon monoxide (CO) and methane (CH&lt;sub&gt;4&lt;/sub&gt;) seriously overlapped. The absorption signal of trace CO gas was annihilated and could not be effectively demodulated, especially in the presence of high concentration of CH&lt;sub&gt;4&lt;/sub&gt;. This problem could not be solved just by accurately selecting the spectral lines due to the band absorption of CH&lt;sub&gt;4&lt;/sub&gt;. Therefore, in this paper, we introduce the support vector regression (SVR) model to deal with the interference between CO and CH&lt;sub&gt;4&lt;/sub&gt; absorption lines. The spectral signals of 14 groups of mixed gases with different concentrations of CO and CH&lt;sub&gt;4&lt;/sub&gt; are used as the training sets, and the five-fold cross-validation is adopted to prevent the model from overfitting. After 15 iterations in 30 seconds, the optimal regression model of CO and CH&lt;sub&gt;4&lt;/sub&gt; can be obtained respectively. Furthermore, it is worth noting that based on the experimental data, the linear kernel function is selected to construct the two gas SVR models, and the parameters of the SVR models are optimized by the sequential minimal optimization(SMO) algorithm. With the assistance of the SVR models, the absorption spectra of the two gases can be demodulated effectively, and finally the accurate measurement results are obtained. The measurement results show that the absolute error of trace CO and CH&lt;sub&gt;4&lt;/sub&gt; concentration(volume fraction of gas) are less than 2 × 10&lt;sup&gt;–6&lt;/sup&gt; and 0.2 × 10&lt;sup&gt;–2&lt;/sup&gt; respectively. Meanwhile, the correlation coefficient between the measured values and the actual values of CO and CH&lt;sub&gt;4&lt;/sub&gt; are 0.998 and 0.9995, respectively. In addition, the dynamic stability for each of the two regression models is fully verified by the experiment of the inflation process. Consequently, this method can eliminate the interference between the overlapping spectra, and can fully meet the requirements for accurately measuring the gas mixture. We hope that the SVR model can provide an effective solution for the real-time monitoring of multi-component gas mixture, and thus greatly improving the adaptability of TDLAS technology in the future.

Measurement of added mass for an object oscillating in viscous fluids using nonlinear self-excited oscillations

In this study, a method of measuring the added mass for an object oscillating in a viscous fluid using nonlinear self-excited oscillations was developed. The added mass produces an additional inertial effect on the vibrating object. In previous methods, the added mass is obtained experimentally from the response frequency and amplitude at the peak in the frequency response curve under a harmonically forced excitation. However, such methods cannot be utilized in highly viscous environments because the peak becomes ambiguous as a result of damping. Moreover, in very high-viscosity environments, the resonance peak ceases to exist in the frequency response curves. To solve this problem, self-excited oscillations were induced in the system using linear velocity feedback. Because linear velocity feedback can be used to eliminate the viscous damping effect when the linear feedback gain is set near the Hopf bifurcation point related to self-excited oscillations, the object becomes self-excited at a frequency equal to the natural frequency of the object oscillating in a vacuum, i.e., the undamped natural frequency. What distinguishes the proposed method from the abovementioned previous methods is that the value of the response is not needed; however, a reduction in the oscillation amplitude is required to obtain accurate measurement results. In the proposed method, to avoid an increase in the response amplitude under the applied linear velocity feedback, nonlinear feedback is also applied to produce a limit cycle similar to that produced in a van der Pol oscillator. A prototype of the measurement system was constructed based on the proposed method. A comparison of the experimentally and theoretically obtained added mass values confirmed the validity of the proposed method for added mass sensing.

An accurate position measurement approach for a single particle in a channel using electrical impedance spectroscopy

A novel position measurement approach for a single particle in a channel using Electrical Impedance Spectroscopy (EIS) only with two pairs of electrodes is proposed. The proposed approach is label-free, non-invasive and is very accurate in measurement domain by using machine learning method. Relationship between the single particle’s position and the measured impedances is described by a set of nonlinear equations showing excellent fitting performance with R-square reaching 0.9999. Finding accurate analytical solution of the particle’s position is the inverse problem, it is tackled by a well-trained Support Vector Regression (SVR) model with the help of multi-frequency EIS. The proposed approach is evaluated by simulation models with a single particle in 100 different positions. The results show that the approach performs an outstanding position measurement accuracy to reach 99.25%. Comparing with EIT, it has more simple structure, less measurement time and more accurate measurement results.

Rekayasa Sistem Data Logger Temperature Berbasis Arduino Uno R3

Storage of goods for production of goods, testing of quality of goods (quality control) to delivery of goods will never be separated from the tribe according to the standards of business activities. interfere with the quality and quantity of the desired production results. Temperature observations are difficult to do continuously because the temperature is too high to observe the zuhu requires a tool that is expected to help, so the LM35 sensor is used to measure the temperature. In order to continuously record temperature, a microcontroller is needed to control the system in question. Therefore, the result to be achieved in this engineering is to design a tool that can record temperature continuously and store temperature recordings for a long period of time to make it easier to implement, analyze and easily get the equipment with accurate measurement results.

Measurement and Evaluation of the Ellipsoid Deviation in Cartesian Coordinates

Ellipsoid part is now increasingly applied to the product manufacturing, while the high-quality ellipsoid part depends not only on the manufacturing and machining techniques, but also on the adopted measurement and evaluation approaches. Based on the typical quadratic surface, an evaluation method of the least squares ellipsoid deviation is proposed in this paper to quantify the form deviation of measured ellipsoid. The method can overcome the weakness of the low measurement adaptability compared with other evaluation methods. With obtaining the coefficients of surface equation to replace the linear superposing of the coordinates of measured points, the measurement error existing in the coordinates of measured points is homogenized and reduced effectively, which prompts to obtain the accurate measurement result. Finally, the results from experimental verifications show that the proposed method is effective for the measurement and evaluation of the ellipsoid deviation in Cartesian coordinates, and the adaptability is also a significant advantage in the measurement and evaluation of geometry deviation.

Atmospheric Correction Thresholds for Ground-Based Radar Interferometry Deformation Monitoring Estimated Using Time Series Analyses

Ground-based radar interferometry (GBSAR) is a useful method to control the stability of engineering objects and elements of geographical spaces at risk of deformation or displacement. To secure accurate and credible measurement results, it is crucial to consider atmospheric conditions as they influence the corrections to distance measurements. These conditions are especially important considering the radar bandwidth used. Measurements for the stability of engineering objects are not always performed in locations where meteorological monitoring is prevalent; however, information about the range of variability in atmospheric corrections is always welcome. The authors present a hybrid method to estimate the probable need of atmospheric corrections, which allows partly eliminating false positive alarms of deformations as caused by atmospheric fluctuations. Unlike the numerous publications on atmospheric reductions focused on the current state of the atmosphere, the proposed solution is based on applying a classic machine learning algorithm designed for the SARIMAX (Seasonal Autoregressive Integrated Moving Average with covariate at time) time series data model for satellite data shared by NASA (National Aeronautics and Space Administration) during the Landsat MODIS (Moderate Resolution Imaging Spectroradiometer) mission before performing residual estimation during the monitoring phase. Example calculations (proof of concept) were made for ten-year satellite data covering a region for experimental flood bank stability observations as performed using the IBIS-L (Image by Interferometric Survey—Landslide) radar and for target monitoring data (ground measurements).

Small Anechoic Chamber Design Method for On-Line and On-Site Passive Intermodulation Measurement

A design method is proposed in this article for on-line (online measurement: measurement when producing devices) and on-site (on-site measurement: measurement when using devices) passive intermodulation (PIM) measurement with a small-size anechoic chamber. In a PIM measurement, the role of an anechoic chamber is to shield extraneous electromagnetic signal and reduce reflection, so that an accurate measurement result can be obtained. However, the chamber itself may introduce new PIM sources due to the nonlinearity in absorbing material and shielding enclosure. The traditional method to lower the influence of chamber to PIM measurement is to design a large-size PIM test chamber in order to reduce the PIM level by path loss. In this article, an innovative design concept of the PIM test chamber is presented by controlling the PIM source level of the anechoic chamber instead of increasing the size of the chamber. It can significantly reduce the chamber size using this method, particularly suitable for on-line and on-site PIM measurement. To implement the concept, absorbing material and shielding enclosure structure with extremely low PIM are developed. The design concept includes defining the worst-case reflection level, estimating the PIM level due to reflected signals, and determining the smallest size of the chamber that meets the design specifications. Finally, two PIM test chambers are built to demonstrate the design concept. PIM measurement results are given to verify the theoretical analysis.

Classification of Breast Cancer Cells Using the Integration of High-Frequency Single-Beam Acoustic Tweezers and Convolutional Neural Networks.

Single-beam acoustic tweezers (SBAT) is a widely used trapping technique to manipulate microscopic particles or cells. Recently, the characterization of a single cancer cell using high-frequency (>30 MHz) SBAT has been reported to determine its invasiveness and metastatic potential. Investigation of cell elasticity and invasiveness is based on the deformability of cells under SBAT’s radiation forces, and in general, more physically deformed cells exhibit higher levels of invasiveness and therefore higher metastatic potential. However, previous imaging analysis to determine substantial differences in cell deformation, where the SBAT is turned ON or OFF, relies on the subjective observation that may vary and requires follow-up evaluations from experts. In this study, we propose an automatic and reliable cancer cell classification method based on SBAT and a convolutional neural network (CNN), which provides objective and accurate quantitative measurement results. We used a custom-designed 50 MHz SBAT transducer to obtain a series of images of deformed human breast cancer cells. CNN-based classification methods with data augmentation applied to collected images determined and validated the metastatic potential of cancer cells. As a result, with the selected optimizers, precision, and recall of the model were found to be greater than 0.95, which highly validates the classification performance of our integrated method. CNN-guided cancer cell deformation analysis using SBAT may be a promising alternative to current histological image analysis, and this pretrained model will significantly reduce the evaluation time for a larger population of cells.

Metrological support of geophysical equipment for acoustic logging

The system of metrological support of geophysical well surveys (GWS) is a system of technical and methodological tools ensuring unity, reliability and accuracy of measurement results. For acoustic logging devices, physical standards with highly stable properties were developed and implemented. They are based on simulation of attenuation and time delay of elastic waves propagating in casing pipes. The design of a calibration device for acoustic video logging equipment made it possible to increase research reliability. The design of a field calibration device allowed for rapid calibration of acoustic equipment in field conditions for improving the GWS quality.

An accurate ultrasonic wind speed and direction measuring method by combining time-difference and phase-difference measurement using coded pulses combination

In this paper, a high-precision and large-range wind speed and direction measuring method is proposed, which can solve the problem that traditional Time of Flight (ToF) method and phase detection method cannot simultaneously take into account measuring accuracy and measurement range. Firstly, based on the binary amplitude modulation and cross-correlation algorithms, the coded pulses combination is designed to measure time difference that the ultrasonic wave arrives different ultrasonic receivers. Because the coded pulses combination can obtain sharper correlation peaks, a more accurate time-difference measurement result can be gained, comparing with the traditional ToF method. Then, for further improving measuring accuracy and resolution of wind speed, a high-precision ±180° digital phase detection method based on double D flip-flops is proposed. Next, by combining time-difference and phase-difference measurement results, the measuring range of wind speed is extended and measuring accuracy is improved. Finally, a wind speed and direction measuring system is set up based on the proposed method. The experimental results show that the wind speed measuring accuracy is ±2%, the resolution is 0.05 m/s and the measurement range can theoretically reach several hundred meters per second; the wind direction measuring accuracy is ±5° and the resolution is 0.5°. At the same time, the standard deviations of the experimental results which are less than 10% demonstrate the stability of the system.

음향라디오시티법을 이용한 잔향수조 음장 해석과 실험검증

The acoustic power is a major acoustical characteristic of an underwater vehicle and could be measured in a reverberant water tank. In order to obtain accurate measurement results, the acoustic field formed by the sound source should be investigated quantitatively in the reverberant water tank. In this research, the acoustic field of a reverberant water tank containing an underwater sound source has been analyzed by using an acoustic radiosity method one of the numerical analysis methods suitable for the acoustic analysis of the highly diffused space. The source level of the underwater sound source and acoustical properties of the water tank input to the numerical analysis have been estimated by applying the reverberant tank plot method through a preliminary experiment result. The comparison of the numerical analysis result with that of the experiment has verified the accuracy of the acoustic radiosity method.

The effect of particle shape in particle detection using inductive sensors

Inductance sensor is one of the commonly used methods in the detection of oil metal particles. The shapes of particles are different, caused by the different forms of wear in oil; however, the effect of particle shapes on the inductive sensors was not under consideration. In order to obtain more accurate measurement results of inductive sensors in metal particle detection and other areas of application, the effect of particle shapes on an inductive sensor is studied in this paper. The inductance change of coil about the ratio of long axis to short axis of particles is obtained in accordance with the experimental validation depending on the cylindrical particles. The results show that the inductance changes are 0.25 nH, 0.32 nH, and 0.92 nH with the ratios of long axis to short axis of particles l/d are 0.67, 1, and 3 with the same volume. It is observed that the inductance change of coil ΔL increases with an increasing ratio of long axis to short axis of particles l/d, which provides a theoretical basis for inductive sensors in metal particle detection and other areas of application.

Power quality—Evaluation of safe operation of observatories

AbstractThe electric power supply of astronomical observatories has to manage a conflict of interest: Observatories are situated at remote locations, they have a high consumption of electric power while measuring electric signals as sensitively as possible. Within the project SLOBATCO, the question did arise, to what extent observatories have to rely on adequate power quality, for example, the perfectly sinusoidal shape of supply voltage and current, to ensure safe operation and accurate measurement results. International power quality standards are put in perspective with requirement specifications for observatories. This contribution describes the motivation, the underlying mechanisms that lead to issues, comments on the challenge in power systems engineering, proposes the instrumentation and installation, and interprets the first results. Experimental results clearly motivate the need for further measurement campaigns, as power‐quality‐related problems are common. A summary is provided together with an outlook and a motivation for future measurement campaigns.