Maximum Measurement Error Research Articles

Analysis of Dialysate pH and Temperature Stability on Hemodialysis Machines Using Internet of Thing Technology

Therapy for kidney replacement with hemodialysis is a treatment that is carried out in patients with Chronic Kidney Failure to survive. The purpose of this study was to determine the stability of the dialysate fluid in the hemodialysis machine by measuring the temperature using the DS18B20 sensor and measuring the dialysate pH using the 4502C sensor on pre and post-hemodialysis. The research method and the manufacture of this module use a pre-experimental research design with the type of research "one group posttest design" the independent variables are the pH value and Dialysate Temperature, the dependent variable is the pH and Temperature Sensor, the control variable is the Traceable Tool. This research made a module using an Esp32 microcontroller system with an LCD that can be monitored with Android via the Internet of Things (IoT) system. 03 and the comparison of the results of the dialysate temperature values ​​at the time of pre and post-obtained the maximum measurement error of 0.2%. From the measurement and analysis data, it can be concluded that there is no effect of pH and temperature values ​​during pre and post hemodialysis.

A Novel Absolute Rotary Encoder Based on Soft Pneumatic Sensing Chambers

The aim of this study is to design and fabricate a novel rotary encoder called soft pneumatic rotary encoder (SPRE) using soft pneumatic sensing chambers (SPSCs). In an SPRE, the volumetric changes developed inside the chambers due to the rotation of an eccentric structure are read by the air pressure sensors and converted into rotary displacements. In this research, for the first time, a soft rotary encoder is developed. Implementing soft measurement methods will bring advantages that are not easily achievable in conventional sensors. The soft nature of SPRE and its electrical isolation from measurement objects have converted it into a proper alternative used in body-interacting mechanisms, such as rehabilitation tools. Besides, its nonmetallic structure paves the way for its utilization as an electromagnetic compatible sensor. With respect to its flexible design properties and availability of its components, this sensor can be designed and manufactured according to the considered need. Here, the SPSC-governing mechanical model was developed by experimental tests and Abaqus finite-element software. Then, the geometrical parameters were evaluated and optimized in Abaqus by exploiting this model, and an SPRE was built based on these conditions. To compensate for the effect of temperature and convert pressure data into angular output, a temperature compensation tube and trigonometric converter were used. The maximum absolute measurement error, resolution, and repeatability of this encoder were 3.34°, 0.062°, and 1.09°, respectively.

A Method of Improving the Length Measurement Accuracy of Metal Parts Using Polarization Vision

Measurement technology based on machine vision has been widely used in various industries. The development of vision measurement technology mainly depends on the process of photosensitive components and the algorithm of processing a target image. In the high-precision dimension measurement of machined metal parts, the high-resolution imaging device usually exposes the cutting texture of the metal surface and affects the accuracy of measurement algorithm. At the same time, the edges of machined metal parts are often chamfered, which makes the edges of objects in the picture overexposed in the lighting measurement environment. These factors reduce the accuracy of dimensioning metal parts using visual measurements. The traditional vision measurement method based on color/gray image makes it difficult to analyze the physical quantities in the light field except for the light intensity, which limits the measurement accuracy. Polarization information can more carefully depict the edge contour edge information in the scene and increase the contrast between the foreground and the background. This paper presents a method to improve the measurement accuracy of machined metal parts by using polarization vision. The incident angle of the light source is optimized according to the complex refractive index of the metal material, and the degree of polarization image with enhanced edge contour features of the ROI (region of interest) is obtained. The high-precision measurement of cylindrical brass motor components is realized by using the method of reprojection transformation correction and maximum correlation template matching (NCC) for rough positioning, as well as the method of edge extraction and optimal fitting. The experimental results show that for copper parts with a tolerance range of ±0.1 mm, the average measurement error and maximum measurement error are within 0.01 mm, which are higher than the existing color/gray image measurement methods.

SURFACE TENSION AND DENSITY OF INDIUM–TIN MELTS AND THEIR DEPENDENCE ON COMPOSITION AND TEMPERATURE

The paper presents the results of measuring the surface tension (σ) and density (ρ) of indium-tin melts. The measurements of σ and ρ were carried out by different methods. The surface tension was measured by the sessile drop method and the maximum pressure in the droplet, while the density was measured by the areometer and sessile drop methods. High-purity metals In-00, tin – VHF were used for research. The maximum measurement error σ is 0.8%, and ρ is 0.2%. The dependence of σ of In–Sn melts on the composition is characterized by an extremum (flat minimum) in the region of equimolar composition. As the temperature increases, the depth of the minimum decreases, and its position shifts towards pure indium. Molar volumes have small positive deviations from additive values. As the temperature increases, the molar volumes approach additive values. The sessile drop method was used to measure the temperature dependences of σ and ρ of In–Sn solutions diluted with indium. It has been shown that indium additives lower the surface tension of tin. Given that the value of the surface tension of indium is higher than that of tin, this result indicates that the surface tension isotherms of the indium-tin system must pass through a minimum.

Blood-pH Optical Measurement: A Model to Compensate for the Effects of Temperature

Under physiological conditions, the human body maintains blood pH within [7.36, 7.44] pH. Small deviations from this range can reveal the onset of pathological states and worsen the patient’s condition. This paper reports the performance analysis of a real-time, non-invasive pH measuring system for extracorporeal circulation (ECC). In particular, this study focuses on the analysis of the effects that the measurand temperature may have on the error in estimating blood pH. Even if the blood temperature in ECC is often thermostated at 37 °C, there are treatments in which the blood temperature is varied by a few Celsius degrees, and the exploited measurement principle - fluorescence - is known to be affected by temperature. First, we verified that the temperature-induced error could exceed the maximum permissible measurement error of ±0.04 pH. Hence a linear correction factor for temperature compensation was proposed. The results obtained showed how the simple addition to the measuring system of a temperature sensor and the use of a linear correction factor can effectively allow maintaining the measurement error within the ±0.04 pH range, even when the fluid - phosphate buffer saline (PBS) and blood - temperature is varied in the range [30, 39] °C.

Justification of the choice of means of controlling the parameters of the crankshaft after processing for the repair size

An assessment of the quality of the control of the parameters of the crankshaft after processing for the repair size was carried out. The company's metrological support system must guarantee the accuracy and quality of the crankshaft repair, eliminating the possibility of defects during subsequent assembly. When repairing engines, defects in the crankshafts are detected, after which they are replaced with new ones or processed according to the repair size. After processing the crankshaft for the repair size, it is necessary to carry out control according to six parameters. It was revealed that to measure the diameters of the main and connecting rod necks of the crankshaft of the Zavolzhsky Engine Plant, as well as their ovality, it is necessary to replace the micrometer 50-75 (0.01) used at the enterprise, the maximum measurement error of which is twice as large as permissible, with a lever bracket 50-75 (0.002) to reduce the measurement error and improve the quality of control. To control the greatest beating of the second, third and fourth root necks relative to the first and fifth root necks, the hour-type indicator used at enterprises fully satisfies the specified conditions, the maximum error does not exceed the permissible one. To control the axial clearance of the already assembled crankshaft along the thrust bearing, dial indicator 0-10 (0.01) is also used, which provides the specified measurement accuracy with a three-fold margin. When measuring the length of the third root neck, the use of a caliper calipers 0-125 (0.05) leads to an excess of the permissible measurement error by 3 times, but there are no other more accurate universal measuring instruments to control this parameter, since the control is carried out by special sponges for measuring holes, which are available only for calipers. It is recommended to design a gauge to measure the length of the third root neck.

Convolutional neural networks open up horizons for luminescence thermometry

Luminescence thermometry has emerged as an effective way to implement non-invasive thermal reading and finds promising applications in many fields. Nevertheless, traditional luminescence thermometric methods, such as the luminescence intensity ratio, are generally carried out based on one single temperature-dependent spectral feature. As a result, other thermal related spectral features were ignored, which radically restricts the sensing performance. Herein, we preliminarily propose a novel strategy for driving luminescence thermometry via convolutional neural network. The trained network is able to autonomously select and extract multiple temperature-dependent features for regression temperature, so the temperature-dependent spectral data can be fully utilized. Using Y3Al5O12: Cr3+ as the temperature sensing material, the proposed thermometry method exhibits high accuracy and strong generalization over the additional test set. The maximum measurement error (emax) in the range of 35–315 °C is about 0.77 °C, accompanied with the average error (eaver) of 0.20 °C. The accuracy of the proposed approach is significantly superior to those achieved by the classical ratiometric technology (emax≈4.05 °C, eaver ~ 1.31 °C) and the widely used multiple linear regression method (emax≈4.27 °C, eaver ~ 1.69 °C), indicating deep learning has the potential to open up a new era of luminescence thermometry.

Vital protocols for PolyWare™ measurement reliability and accuracy.

PolyWare™ software (PW) has been exclusively used in the majority of polyethylene wear studies of total hip arthroplasty (THA). PW measurements can be significantly inaccurate and unrepeatable, depending on imaging conditions or subjective manipulation choices. In this regard, this study aims to shed light on the conditions needed to achieve the best accuracy and reliability of PW measurements. The experiment looked at how PW fluctuated based on several measurement conditions. x-ray images of in-vitro THA prostheses were acquired under a clinical x-ray scanning condition. A linear wear rate of 6.67 mm was simulated in combination with an acetabular lateral inclination of 36.6° and anteversion of 9.0°. Among all the imported x-ray images, those with a resolution of 1,076 × 1,076 exhibited the best standard deviation in wear measurements as small as 0.01 mm and the lowest frequencies of blurriness. The edge detection area specified as non-square and off the femoral head center exhibited the most blurriness. The x-ray image that scans a femoral head eccentrically placed by 15 cm superior to the x-ray beam center led to a maximum acetabular anteversion measurement error of 5.3°. Because PW has been the only polyethylene wear measurement tool used, identifying its sources of error and devising a countermeasure are of the utmost importance. The results call for PW users to observe the following measurement protocols: (1) the original x-ray image must be a 1,076 × 1,076 square; (2) the edge detection area must be specified as a square with edge lengths of 5 times the diameter of the femoral head, centered at the femoral head center; and (3) the femoral head center or acetabular center must be positioned as close to the center line of the x-ray beam as possible when scanning.

A Fiber-Based Chromatic Dispersion Probe for Simultaneous Measurement of X-Axis and Z-Axis Displacements with Nanometric Resolutions.

In this paper, a fiber-based chromatic dispersion probe for simultaneous measurement of X-axis and Z-axis displacements with nanometric resolutions by using the full width at half maxima (FWHM) of the detected spectral signal has been proposed and demonstrated. For X-axis, FWHM is employed for indicating the X-axis displacement based on the fact that the FWHM remains almost constant with the varying Z-axis displacement of the fiber detector and shows a linear relationship with the X-axis displacement within a specific Z-axis displacement range. For the Z-axis, the linear relationship between the centroid wavelength λ of the detected spectral signal and the Z-axis displacement is employed for indicating the Z-axis displacement based on the fact that the sensitivity (slope of the λ-Z curve) is also linear with X-axis displacement within a certain X-axis displacement range. Theoretical and experimental investigations have verified the feasibility of the proposed chromatic dispersion probe, which yields X- and Z-axis measurement ranges of 2.3 μm and 15 μm and X- and Z-axis measurement resolutions of better than 25 nm and 50 nm, respectively. Experiments were further performed to evaluate the basic performance of the prototype probe and the maximum measurement errors were less than 10 nm and 60 nm for X- and Z-axis displacements, respectively.

Establishment of a metric to characterize retroreflector properties using a consumer-grade colour camera

Abstract The coefficients of retroreflection and chromaticity coordinates are critical metrics for determining the quality of a retroreflector. However, conventional retroreflection measurement techniques rely heavily on the night-time colour, size and characteristics of the sample being measured. This complicates the measurement process and leads to deviations in the test results. In addition, chromaticity cannot be determined using this approach. Therefore, it is necessary to improve the measurement accuracy, simplify the measurement process and achieve the measurement of the traffic sign RA and chromaticity coordinates simultaneously. In this study, an improved method for retroreflector characterization using imaging was proposed. This allowed for the measurement of the coefficients of retroreflection and the chromaticity coordinates simultaneously, and only a white standard sample was required for calibration. The primary components of the proposed system included a lighting projector, a receiver, two motorized rotational stages, a retroreflective sample holder and customized software that using scaling factors to convert a digital signal into sample retroreflection coefficients and retroreflective chromaticity coordinates. The experimental results indicated that the raw data output from the camera exhibited a positive correlation relationship with the luminous flux from the surface of the retroreflector. The maximum measurement errors for the retroreflection and chromaticity were −12.2 cd/(lx·m2) and −2.09%, respectively. This method was inexpensive and convenient, used a commercially available digital camera, could help to identify defects in retroreflection and chromaticity for retroreflective sheeting and led to increased accessibility for the quality control of retroreflective sheeting.

Distributed Temperature and Curvature Sensing Based on Raman Scattering in Few-Mode Fiber

We propose and experimentally demonstrate a distributed temperature and curvature sensing method based on spontaneous Raman backscattered lights in a few-mode optical fiber. A loop structure is used to demodulate the distributed temperature information using the Raman anti-Stokes (AS) scattering lights. And the fiber curvature is estimated by the loss of Raman Stokes (S) light. This system can measure temperature and curvature at the same position of the fiber simultaneously. The experimental results show that the temperature uncertainty and spatial resolution can reach up to 0.24 °C and 1.8 m on 6 km sensing fiber. Besides, the maximum measurement error is 0.11 cm within the curvature measurement range of 0.5–3 cm.

Study on surface crack detection of ferromagnetic materials based on remanence

Remanence detection is a technique of electromagnetic non-destructive testing (NDT). This paper studies a quantitative detection method for surface cracks of ferromagnetic materials based on remanence. The finite element analysis software COMSOL Multiphysics was used to establish the remanence detection model and the 'moving grid' function was used to realise the simulation of the remanence signal. The leakage magnetic field occurs due to the distortion of the magnetic induction lines near the surface cracks after ferromagnetic materials are magnetised. Remanence detection uses the leakage magnetic field to detect cracks. The relationship of the leakage magnetic field versus the crack depth and width was analysed using the magnetic dipole model. The relationship between the crack size and the remanence signal was verified by measuring the surface remanence signal of cracks of different sizes. The characteristic parameters related to the crack size were extracted and the regression model between the characteristic parameters and the crack size was established. For the remanence detection, the maximum error of width prediction was 16.25% and the maximum error of depth prediction was 18.48%. For the magnetic flux leakage (MFL) detection, the maximum error of width prediction was 12.1% and the maximum error of depth prediction was 12.32%. Under the same experimental conditions, the maximum error of crack width measurement of remanence detection was 4.15% larger than that of MFL detection and the maximum error of depth was 6.16% larger than that of MFL detection.

Research on accurate perception and control system of fertilization amount for corn fertilization planter.

At present, there are excessive fertilizer use and poor uniformity of fertilizer discharge in corn fertilizer planter. The key difficulty is that accurate perception and control of fertilizer amount has not been solved. Aiming at the above problems, a set of accurate perception and control system applied to corn fertilization planter was studied. According to the difference in dielectric properties between fertilizer and air, a sensor for online detection of fertilizer amount based on capacitance method was designed. And the relationship model of mass flow rate for N, P, K fertilizer and capacitance output was established. In order to reduce the influence of pulsation on fertilization flow, a high-precision fertilizer flow control system for fertilization planter based on the fertilizer flow feedback and PID control method was designed. The validated results showed that the maximum measurement error between the relationship model and capacitance output was 3.75%. As the temperature rises from room temperature to 55°C, the differential capacitance change rate of the sensor was less than 3%. The steady-state error of fertilizer discharge was less than 2%. The field experiment of the accurate perception and control system for corn fertilization amount show that the electric drive fertilization system has good consistency, the maximum and average variation coefficient of fertilization were 3.74%, 1.6%, respectively, and the variable control accuracy was greater than 97%. The control accuracy of the grain spacing control by electric drive seed metering was 98%. Therefore, the precision fertilization control system in this study can realize high-precision and on-demand fertilization. It is of great significance to realize the intelligence and precision for corn fertilization planter.

Phase-shifting digital holographic microscopy for microstructure measurement by sweeping the repetition rate of femtosecond laser

This paper proposes a phase-shifting digital holographic microscopy (PSDHM) for microstructure measurement by sweeping the repetition rate of femtosecond laser, and a multiple reflection arrangement between two quasi-parallel mirrors is constructed for optical multiplication. High precision phase-shifting can be achieved by sweeping the repetition rate of the femtosecond laser referenced to a Rb atomic clock without any mechanical sweeping. Optical multiplication can shorten the spatial distance of the optical delay line used for pulses alignment, make the PSDHM structure compact and stable, and avoid certain environmental disturbances. In the experiments, a ten-step phase-shifting test was first carried out for evaluating the phase-shifting accuracy, and the phase-shifting error was calculated to be in the range of −1° to 0.25°. Then, a USAF 1951 resolution target and a microstructure standard target were measured using a four-step PSDHM, and the measurement results were compared with those from a stylus profiler and a white light interferometer, respectively. The lateral resolution of PSDHM was tested to be about 2.1 μm, and the maximum error of the longitudinal measurement was within 6 nm. Experiments verify that the PSDHM system has good performance in terms of phase-shifting accuracy, surface topography measurement and coherent noise suppression.

Full-Bridge Design for Error Reduction of 3-D Printed Mechanical Wind Sensor

In this article, a 3-D printed mechanical wind sensor with reduced measurement errors is demonstrated. This sensor consists of a cylindrical sensing structure arranged vertically in the center of a cross-shape cantilever. Eight strain gauges are symmetrically designed on the four beams of the cross cantilever to measure the airflow-induced cantilever deformation. With these eight strain gauges, two sets of Wheatstone full-bridge circuits can be constructed, enabling the measurement errors of the mechanical wind sensor to reduce remarkably. The experimental results indicate that, compared with the four-strain-gauge mechanical wind sensor in the previous work, the eight-strain-gauge design presented in this article can achieve a 62.4% sensitivity improvement for wind speed measurement. This increased sensitivity allows the wind sensor to realize a maximum speed measurement error of 0.53 m/s in the range of 0–30 m/s, achieving a 39.1% reduction compared with 0.87 m/s of the previous four-strain-gauge sensor. In addition, the test results also show that the proposed full-bridge sensor can define the airflow direction over the full range of 360° with a maximum error of 6°, which is 2° less than the four-strain-gauge device.

Compensated Resistance Matrix Approach for Readout of the 2-D Resistive Sensor Array for High-Temperature Measurement

A 2-D resistive sensor array (RSA), which has the advantages of high stability and easy implementation, is widely used in the measurement of surface parameters. Nevertheless, at present, resistance arrays are usually used to measure surface parameters under normal temperature conditions. But there is a lack of research in high-temperature applications that urgently require surface parameter measurement of components. In a high-temperature environment, wires made of high-temperature-resistant materials will lead to an increase in wire resistance, resulting in measurement errors. Through the simulation, we verified that the small wire resistance will cause a huge error. There will be a maximum measurement error of 40% in the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10\times10$ </tex-math></inline-formula> array at 500 °C, and the error increases with increasing temperature and array size. To solve the measurement error caused by the wire resistance, we derived the formula of the circuit model and proposed the compensated resistance matrix approach (CRMA) for the accurate measurement of the 2-D RSA at high temperatures. The CRMA can control the mean square error of the measurement to 10−7 and achieve accurate measurement of the temperature field. Furthermore, an experimental platform for verifying the CRMA was built, and the verification experiments were carried out. The results showed that the measurement error of this method can be controlled below 2% under high-temperature conditions, and it can be used in accurate measurements that require low complexity and are used in high-temperature environments.

A non-iterative calibration method for the extrinsic parameters of binocular stereo vision considering the line constraints

The calibration accuracy of the binocular stereo vision system is important for precision measurement. The extrinsic parameters (structure parameters), which describe the relative position of the two cameras, need to be optimized before measurement. The optimization of extrinsic parameters is accomplished through iterations of minimizing an objective function. It is hard to decide the optimum objective function between various objective functions. The calibration accuracy is decreased when the objective function is incorrect, which can result in excessive optimization or fall into a local minimum (ambiguous solution), notably for planar targets. In this paper, we proposed a non-iterative calibration method for the extrinsic parameters of binocular stereo vision considering the line constraints of a planar target. Each line formed by every two calibration points can provide two independent constraints. Additional equations for solving the extrinsic parameters can be obtained using these constraints. We added these equations to the equations system established by the homography of the target plane and image plane. The extrinsic parameters of the binocular stereo vision system can be solved non-iteratively. Using the parameters calibrated by our method, greater improvements in the accuracy and stability of measurements occurred, compared to other existing methods. In the −45° to +45° measuring range, the maximum measurement error is no more than 0.037° and the average measurement error is no more than 0.022°. In the 0 to 28 mm measuring range, the maximum measurement error is no more than 0.039 mm and the average measurement error is no more than 0.012 mm. The maximum length measurement error is no more than 0.038 mm and the average length measurement error is no more than 0.011 mm while measuring a 240 × 180 mm2 target.

Binocular visual pendulum angle detection and anti-swing control of quadrotor suspension system

Different from the pendulum angle detection by the optical capture system in the indoor environment, it is difficult to detect the pendulum angle of quadrotor suspension system in the outdoor environment. This paper presents a pendulum angle vision measurement scheme based on the model of the quadrotor suspension system, and applied to the quadrotor anti-swing control scheme with feedforward controller. The theoretical expression of the coordinate relationship between the pendulum angle and the spherical symbol is obtained by establishing the mathematical model of the quadrotor suspension system. The coordinates of spherical symbol fixed to the payload are detected by the visual algorithm. Simulations and experiments show that proposed method can accurately identify spherical symbol in sufficient light, and the maximum measurement error of [Formula: see text] angle is −0.024 rad and [Formula: see text] angle is −0.068 rad in the Gazebo simulation. Meanwhile, the results in MATLAB simulation indicate the anti-swing control scheme with feedforward controller can effectively restrain the payload’s swing.

An Online Junction Temperature Monitoring Correction Method for SiC MOSFETs at Different Parasitic Parameters

Due to the remarkable performance of silicon carbide (SiC) metal–oxide–semiconductor field-effect transistor (MOSFET) on high temperature, it is promising in future applications in various applications. The accurate online junction temperature based on dynamic temperature-sensitive electrical parameters (TSEPs) is significant for the protection and condition monitoring, which can prolong or monitor the lifetime of SiC MOSFET devices. In this article, four different dynamic TSEPs, including turn-on delay time, turn-off delay time, and maximum current turn-on and turn-off switching rates, are theoretically analyzed taking the parasitic parameters into consideration. The experimental analysis of the influence of parasitic parameters ’ dynamic TSEPs is carried on using a buck converter test setup. Based on the theoretical and experimental analyses, a junction temperature correction method is proposed for SiC MOSFET. The online junction temperature monitoring experiments are used to verify the accuracy and effectiveness of the proposed method. The results show that the proposed correction method can largely eliminate the junction temperature monitoring error at different parasitic parameters. The maximum measurement error is reduced from 147 °C to 4.7 °C after correction.

Identification of centrifugal pump flow based on feature recognition

The flow rate of water pumps is a crucial parameter for diagnosis, optimisation and renovation of transmission and distribution systems. To solve the problems of limited measurement conditions, inadequate consideration of operational wear and tear, and large deviations in the fitted flow curves when obtaining flow rates by direct measurement or characteristic curve fitting, this paper proposes a method for identification of centrifugal pump flow rates based on feature recognition. The method combines the unknown structural parameters of a centrifugal pump with three simple and easy-to-measure operating data: pump head, frequency and power, to obtain the pump characteristics and construct a model for identification of centrifugal pump flow. At the same time, the influence of measurement errors and wear and tear on the model’s accuracy is investigated. The results show that the maximum relative error of the pump operating flow obtained by the method is 2.27%, a slight deviation from the actual measured flow. The maximum relative error of flow rate is 2.7% when a maximum measurement error of ± 0.1%, 0.5% and ± (3%+5) for the required operational data, respectively, indicating that the method has a high resistance to interference. The method considers the different degrees of operating wear and tear of the pumps, saves on equipment input and enables fast and accurate identification of the flow rate of the pumps under different operating conditions.