Calibration Principle Research Articles

Tension identification method of structural cable based on calibration principle in engineering

This paper proposes a practical cable tension identification method based on the calibration principle for in-service building cables in engineering. Based on the beam model theory of vibration method and Zui. H theory formula, a general cable force-frequency model is proposed. Then, the tension and frequency of the cable during the construction is calibrated to fit the model parameters. The cable force identification is realized by testing the cable frequency during service. In this paper, the cable force frequency calibration test is carried out on the semi-parallel wire cable and typical pre-stressed structures, and the cable force frequency database is obtained. The tension prediction model is fitted by some data and verified by the rest data. The root mean square error and the goodness of fit are calculated, and the applicability of the method is verified by comparing with the existing method. The cable tension identification method provides a new idea for the cable force identification of in-service cables in engineering.

Calibration error study of binocular stereo camera

The calibration accuracy of the camera largely affects the accuracy of 3D measurement, so this paper researches on the calibration error of the binocular stereo camera, introduces the imaging model of the camera, conducts the experiment of calibration according to the principle of Zhang Zhengyou's calibration, and responds to the calibration accuracy by the reprojection error, the experimental results show that the calibration meets the requirements and the average error can reach 0.05pixels.

Online deviation measurement system of the strip in the finishing process based on machine vision

In the production of hot rolling, the deviation of the strip in the finishing process has always been a technical problem that plagues enterprises. However, there is currently no effective measurement method for the deviation of the strip in the finishing process. To this end, this paper proposed a non-contact strip deviation online measurement scheme based on machine vision technology and image detection. On the one hand, the principle of deviation measurement of binocular line scan camera and the error compensation model was established. On the other hand, a new calibration principle of binocular line scan camera was established, corresponding to the measurement principle. Finally, the real-time deviation of the strip was calculated. The field experiment showed that the strip deviation measurement system in this paper has high measurement precision and could be well adapted to the changing of the strip height.

Rapid Calibration of the Projector in Structured Light Systems Based on Brox Optical Flow Estimation

In this work, we propose a rapid calibration technique for locating the projector in the structured light measurement system. Using Brox optical flow, the calibration of the three-dimensional (3-D) coordinates of the projector only requires two images captured before and after the motion of the calibration plate. The calibration principle presented in geometry depicts the relation between the position of the projector, the camera, and the optical flow caused by the movement of the calibration plate. Some important influences on accuracy are discussed, such as the environmental noises and the localization error of the camera and the calibration plate, illustrated by numerical simulations. The simulation results show that the relative errors of the projector calibration results are less than 0.8% and 1% in the case of the calibration images polluted by Gaussian noise of SNR of 40 dB and 20 dB, respectively. An actual experiment measured a square standard block, and a circular thin plate verifies the proposed method’s feasibility and practicality. The results show that the height distributions of the two specimens are in good agreement with their true values, and the maximum absolute errors are 0.1 mm and 0.08 mm, respectively.

Application of Image Denoising Algorithm and Data Mining in Psychological Teaching Quality Evaluation

In order to improve the psychological teaching quality of college students, this paper combines image denoising algorithm and data mining algorithm to construct a psychological teaching quality evaluation system. The denoising algorithm is mainly used to identify the behavior and expressions of the students so as to explore the psychological state of the students. Moreover, this paper combines the data mining algorithm to carry out the quantitative analysis of students’ psychological state and analyzes and introduces the calibration principle of Dirckx method in detail to improve it and then forms a new calibration method. In addition, based on the arctangent function, this paper proposes a new two-frame random phase-shift fringe image phase shift extraction algorithm. The research results show that the image denoising algorithm and data mining proposed in this paper have a good effect in the evaluation method of psychological teaching quality and can play a good role in the improvement of students’ mental health.

Linear Laser Scanning Measurement Method Tracking by a Binocular Vision

The 3D scanning of a freeform structure relies on the laser probe and the localization system. The localization system, determining the effect of the point cloud reconstruction, will generate positioning errors when the laser probe works in complex paths with a fast speed. To reduce the errors, in this paper, a linear laser scanning measurement method is proposed based on binocular vision calibration. A simple and effective eight-point positioning marker attached to the scanner is proposed to complete the positioning and tracking procedure. Based on this, the method of marked point detection based on image moment and the principle of global coordinate system calibration are introduced in detail. According to the invariance principle of space distance, the corresponding points matching method between different coordinate systems is designed. The experimental results show that the binocular vision system can complete localization under different light intensities and complex environments, and that the repeated translation error of the binocular vision system is less than 0.22 mm, while the rotation error is less than 0.15°. The repeated error of the measurement system is less than 0.36 mm, which can meet the requirements of the 3D shape measurement of the complex workpiece.

Gas temperature meter

Purpose: of the article is to develop a digital portable gas temperature meter in the range of -50…+600°C. To measure the temperature of dusty gas flows in the air pollution sources with the least significant digit of the digital device 1°C. Design/methodology/approach: The microprocessor measuring unit, probe and software is proposed. It leads to build a high-precision temperature meter based on a thin film sensor HM220 type "pt100". Findings: The calculation of the electrical schematic diagram parameters for signal conditioning of the sensor relative to the input range of the analog-to-digital converter. The experimental measuring unit and the probe of the gas temperature meter are assembled. The principle of the gas temperature meter calibration with the help of a precision resistance box MSR-60M is considered. The experimental gas temperature meter has a total standard uncertainty determined by type B for a maximum value of the measurement range of 1.94°C. The error of the sensor "pt100" makes the largest contribution to the total standard uncertainty, so the error increases in proportion to the value of the measured temperature. Research limitations/implications: On the basis of the proposed design of gas temperature meter it is possible to construct devices with various lengths of probes. Practical implications: The proposed meter is designed for environmental laboratories that measure the velocity, flow and sampling of dust and gas emissions from sources of air pollution. Originality/value: The device design differs due to the use of thermostable wire made of constantan as extending conductors of the temperature sensor, which is included in the unbalanced Wheatstone bridge. This solution allows the use of unipolar power supply 3.3 V for both analog and digital part of the meter. Temperature meter based on a thin film resistance thermometer is characterized by relative ease of manufacture, low material consumption, cost and high reliability.

Enforcement of foreign judgments, systemic calibration, and the global law market

Abstract There are important reasons for states to recognize and enforce the judgments of other states’ courts. There are also reasons that may militate against recognition or enforcement of certain foreign judgments, making it appropriate to calibrate or “fine tune” the presumption favoring recognition and enforcement so it is not applied too broadly. Most calibration principles, such as the principle that a judgment from a court lacking jurisdiction should not be recognized, are case-specific. However, one calibration principle that is, to our knowledge, unique to the law of the United States stands out: the principle of systemic calibration, according to which U.S. courts must not recognize or enforce foreign judgments “rendered under a system which does not provide impartial tribunals or procedures compatible with the requirements of due process of law.” In this Article, we aim to shed empirical light on how U.S.-style systemic calibration operates in practice. We find that state-of-origin indicator scores related to systemic adequacy are on average higher when U.S. courts recognize or enforce foreign judgments than when they refuse to do so. Moreover, the probability of recognition and enforcement increases as these indicator scores increase. However, in only six of the 587 opinions in our dataset did a court refuse recognition or enforcement based explicitly on the systemic inadequacy ground. Thus, while the level of systemic calibration in U.S. courts is high, it is mostly achieved implicitly. Finally, even judgments from states with low systemic adequacy scores are sometimes recognized or enforced by U.S. courts.

Analysis of strong-arm comparator with auxiliary pair for offset calibration

This paper analyzes the principle of the input-referred off calibration using the auxiliary pair for Strong-Arm comparator as well as its impact from the additional common-mode current and parasitic capacitance on the input-referred noise, offset, and decision time in detail. The comparison with the simulation results demonstrates the accurate prediction with the proposed analysis. This paper also discusses the design guideline to optimize the Strong-Arm comparator with the auxiliary pair for offset calibration.

Optical stimulation systems for studying human vision.

This chapter describes the most common setups that scientists use for generating light stimulation, from lab-made approaches to commercially available technologies. The studied optical stimulation systems are divided into nonimage-forming and image-forming arrangements. Two classical systems widely used are among the first: the Maxwellian view system and the Ganzfeld stimulator. Between the image-forming arrangements, the focus is on approaches that consider off-the-shelf devices and the recent appearance of multi-primary displays, which allow the inclusion of more primaries and the generation of stimulation for independent and combined photoreceptor and postreceptoral excitations. Some of the several limitations that can have important implications in research practice are also examined, such as those related to color gamut, sampling frequency, light range, and spatial resolution. Since experimentation on how optical radiation is processed by the human neural system requires the reliability of the parameters and variables under study to be assured, the characterization and consequent calibration of experimental devices are essential. Therefore the chapter discusses a set of characterization and calibration principles that researchers should consider when carrying out experiments with the described optical stimulators. Outstanding characteristics are stimulator response curve, primaries' spectral power distribution, additivity, modulation transfer function, and temporal stability. Finally, some possible sources of artifacts that researchers should consider when these stimulators are used are presented. Throughout this last section, data based on different optical stimulator measurements is provided.

Calibration Method for Industrial Robots Based on the Principle of Perigon Error Close

For the problem that the self-error of industrial robot calibration device has influence on calibration accuracy, a calibration method of industrial robots based on the principle of Perigon Error Close is proposed. In the method, the theory that the sum of circular indexing interval errors around a circle is zero is applied to robot calibration to improve robot calibration accuracy. The calibration principle of the proposed method is provided in detail and the calibration equation is derived in this paper. The calibration system based on the proposed method was constructed with one semiconductor laser and two position sensing detectors (PSDs) fixed on a rotary table. Based on the position error data obtained from laser spot position on the PSDs, the robot kinematics parameter errors were identified by using Levenberg Marquardt (LM) algorithm. The robot calibration experimental setup was constructed and the related verification experiments were carried out. The model parameter identification experiment validates the feasibility of the proposed method for industrial robot calibration. The calibration compensation experiment results of industrial robots show that the maximum position error of the robot is reduced by 71.9% and the average position error is reduced by 77.8%, which validates the effectiveness of the proposed method for industrial robot calibration.

Experimental research on the dynamic characteristics of underwater shock wave pressure sensor

With respect to the calibration of dynamic pressure measurement system under specific underwater explosion application environment, this paper has proposed an experimental calculation method for the dynamic characteristics of underwater shock water pressure sensor based on a preloaded water shock tube. This was done by analyzing the dynamic calibration principles of the preloaded water shock tube and studying the dynamic influencing factors pertaining to the sensor. Moreover, a dynamic calibration experiment for the sensor was also designed based on a comparative calibration method, through which a calculation method for the dynamic characteristics of underwater shock wave pressure sensor was acquired. The experimental results have proven that applying preloaded water shock tube can effectively acquire the dynamic characteristics of the pressure sensor, thereby providing a research framework for the dynamic calibration of underwater explosion shock wave pressure sensor.

Multiscale Intelligent Inversion of Water-Conducting Fractured Zone in Coal Mine Based on Elastic Modulus Calibration Rate Response and Its Application: A Case Study of Ningdong Mining Area

Abstract Water-conducting fractured zone is the direct inducement of water inrush, water losing, and environmental deterioration in coal mines. How to predict the height of water-conducting fractured zone economically and accurately has always been the research difficulty of water-preserved mining. The paper selects the Meihuajing coal mine in Ningdong mining area as the engineering background. Firstly, transform the distribution law of the water-conducting fractured zone into a deterioration mechanism of coal-rock strength under the action of water-rock. Through laboratory tests, the water-rock coupling degradation law of rock mass under uniaxial action is revealed, and an intelligent statistical model of damage rate response under different water content is proposed. Secondly, based on the cross-scale elastic modulus calibration principle and the rate response intelligent statistical model proposed above, the borehole elastic modulus instrument is used to quantitatively characterize the strength characteristics of elastic modulus rate response law and field lithological parameters. Finally, based on the 18 samples of the water-conducting fractured zone, a height prediction model of a water-conducting fractured zone based on the measured value of elastic modulus is proposed by using the method of PSO-SVR. Taking R2 and RMSE as evaluation indexes, the error comparison between PSO-SVR and the empirical formula is carried out. Research indicates that, compared with the empirical formula, R2 of the PSO-SVR model increased by 18.3% and RMSE decreased by 92.7%. The predicted value of the PSO-SVR is consistent with the measured value, which significantly improves the prediction accuracy of the height of the water-conducting fractured zone. It provides a theoretical basis and technical support for the coordinated development of safe and efficient development of coal and ecological protection in Ningdong mining area.

Impact of Measurement Uncertainty on Modeling of Dielectric Relaxation in Aqueous Solutions

Uncertainty analysis is performed on a coaxial probe-based dielectric spectroscopy measurement platform, and its impact on the modeling of dielectric relaxation in an aqueous solution is further analyzed. Based on the characterization theory and calibration principle of the platform, uncertainty due to the different available expressions and parameters of the calibration liquid is calculated. Then, repeatability uncertainty related to drift of the measurement platform, environment change, position variation of the probe immersed in the liquid under test (LUT), and so on is analyzed. Next, three types of water–alcohol mixtures and one group of glucose solutions are measured using the platform. Based on the measurement results, the best model is chosen to analyze the frequency dependence of the solutions’ relaxation properties. In addition, based on the uncertainty analysis, appropriate mathematical formulas are provided to model the composition dependence of the solutions’ relaxation parameters, which can be used as a liquid detection technique for chemical and biological applications.

Trust Miscalibration Is Sometimes Necessary: An Empirical Study and a Computational Model

The literature on trust seems to have reached a consensus that appropriately calibrated trust in humans or machines is highly desirable; miscalibrated (i.e., over- or under-) trust has been thought to only have negative consequences (i.e., over-reliance or under-utilization). While not invalidating the general idea of trust calibration, a published computational cognitive model of trust in strategic interaction predicts that some local and temporary violations of the trust calibration principle are critical for sustained success in strategic situations characterized by interdependence and uncertainty (e.g., trust game, prisoner’s dilemma, and Hawk-dove). This paper presents empirical and computational modeling work aimed at testing the predictions of under- and over-trust in an extension of the trust game, the multi-arm trust game, that captures some important characteristics of real-world interpersonal and human-machine interactions, such as the ability to choose when and with whom to interact among multiple agents. As predicted by our previous model, we found that, under conditions of increased trust necessity, participants actively reconstructed their trust-investment portfolios by discounting their trust in their previously trusted counterparts and attempting to develop trust with the counterparts that they previously distrusted. We argue that studying these exceptions of the principle of trust calibration might be critical for understanding long-term trust calibration in dynamic environments.

Laser scanning\u2013based straightness measurement of precision bright steel rods at one point

In industrial manufacturing of bright steel rods, one important quality factor is the straightness or straightness deviation. Depending on the application, deviations of less than 0.1 mm per meter rod length are desired and can be reached with state-of-the-art manufacturing equipment. Such high-quality requirements can only be guaranteed with continuous quality control. Manual straightness measurements conducted offline using a dial gauge provide accurate results on single positions of the rod. We propose a contactless, optical measurement technique based on laser scanning which has the potential to be used inline during production to inspect all rods over the entire length. Only for calibration of the system the rod needs to be turned around its axis. For the measurement of straightness deviation, it is not required to turn the rod. The method is based on evaluating the intensity signal of the reflected laser radiation against the scan angle. It is shown that in combination with an accurate calibration, this signal can be used to determine the rod’s deviation from a straight rod. We explain the measurement and calibration principle as well as data evaluation. We present the experimental setup and first measurement results on a single position on several samples. For a homogeneous sample surface and neglecting laser drift, accuracy and precision were determined to be in the range of 10–20 μm. We discuss the working principle of a potential inline system.

In situ monitoring of elemental losses and gains during weathering using the spatial element patterns obtained by portable XRF

Weathering would produce damage to objects. This paper proposed a method to monitor geochemical variations on outcrop surfaces, through in situ measurement using portable X-ray fluorescence (pXRF) analyser at high spatial resolution, and qualitative and quantitative determination of elemental gains and losses based on spatial patterns of elemental concentrations and calculated enrichment factors. Taking into account the representativeness of sample matrices, a weathering diabase profile consisting of saprolite and the corresponding rock was selected. Comparisons were made between the laboratory results and the pXRF results, besides, the difference between the two test modes based on different calibration principles (mining mode: Fundamental Parameters calibration; soil mode: Compton normalization) in measuring multi-matrices was evaluated. The pXRF results were comparable to the laboratory results for most elements (excellent correlation: Ca, K, Mn, Mo, Zn, and V; good correlation: Ti, Rb, and Sr; moderate correlation: Fe, Si, and Zr; bad correlation: Ba and Al). Much lower readings for light elements would be obtained from the mining mode when loose samples were analysed, and the soil mode was more suitable for measuring a weathering profile, and if light elements such as Mg, Al, and Si are involved, the mining mode can be used, and the reading ranges of the light elements will require verification. Elemental enrichment and depletion were discussed based the spatial pattern of elemental concentrations, and four groups of elements of continuous emigration, slight emigration, local immigration caused by later veins, and continuous immigration with weathering were effectively discriminated based on the spatial pattern of elemental enrichment factors in the profile. Using this method we could rapidly ascertain the migration characteristics of multielements and locate the spatial positions of intense weathering, providing a new insight into the measuring and monitoring of chemical changes with weathering in rock outcrop, building stone, and so on.

Numerical simulation study of free space method for measuring sample permittivity

The composition and performance of the material can be expressed by the permittivity. The paper introduces the measurement principle of free space method and TRL calibration principle, the calculation formula of the sample permittivity is theoretically analysed, a horn lens antenna is designed to simulate the emission of plane waves, and numerical simulation software is used for simulation and optimization. In the working frequency range, the voltage standing wave ratio of the antenna is less than 1.49, and the maximum gain is 21.8dB. A free space measurement system is established in the software to measure the sample permittivity with different thicknesses, and compare the calculated value with the actual value. The results show that the root mean square error of the real part is less than 5.3%, and the root mean square error of the imaginary part is less than 1.3%. The correctness and applicability of the formula for calculating the permittivity are also proved.

Highly accurate imaging based position measurement using holographic point replication

The experimental approach of a highly accurate imaging based stereo measurement setup with a total measurement volume of 140 mm × 100 mm × 50 mm is presented. The system can detect the position of multiple target points (LEDs) in a calibrated volume of 100 mm × 75 mm × 24 mm with an accuracy of σx=0.367μm, σy=0.373μm and σz=0.437μm. This high accuracy is reached by holographically replicating each point light source to a predefined pattern (cluster) of spots on the camera sensor and averaging the center positions of all spots. We present a detailed description of the principle, the process and results of calibration including deformation compensation and stability measurements, as well as the results of two- and three-dimensional trajectory measurements. To validate the performance and accuracy of the measurement setup, interferometers are employed as reference sensors. The residual error of a two-dimensional trajectory of distance D=277μm is σd=0.242μm and for a three-dimensional trajectory of distance D=57.2 mm it is σd = 0.674 μm.

UNCERTAINTY EVALUATION ON THE CALIBRATION OF DC & AC CURRENT GENERATED BY COMBINATION OF AC/DC CURRENT SOURCE AND CURRENT COIL USING SUBSTITUTION METHOD

Development of measurement method for calibrating current coil continues to be made to maintain measurement traceability for high DC and AC current scope which are generally used for clamp meter calibration services in Laboratory of National Measurement Standard for Electricity and Time (Lab NMS ET). This paper describes the uncertainty evaluation method developed in Lab NMS ET for calibrating high DC and AC current from 50 A up to 990 A generated by a single system consisted of a DC/AC current source and a 50-turn current coil. The uncertainty analysis was carried out based on the calibration principle using the substitution method combined with the principle of multiplication between output current of a DC/AC current source and a 50-turn current coil. It resulted in six source of uncertainty component derived from the current source, the current coil, and a meter. Their sensitivity coefficients were calculated as well to adapt the unit of each uncertainty budget to the final unit in Ampere (A). Using this uncertainty evaluation principle, at the measuring range of 50 A to 990 A, the expanded uncertainties for DC current were spanned from 0.69% to 1%. As for AC current, they were spanned from 0.8% to 1.4%. The major uncertainty contribution comes from the current coil which is representation of uncertainty due to various factors affecting the current coil performance. Validation had been carried out and the normalized error (EN number) values were in the range -0.48 to -0.16 for DC current measurements and in the range of -0.06 to 0.16 for AC current measurements.