Search

Meteor radar is a widely used technique for measuring wind in the mesosphere and lower thermosphere, with the key advantage of being unaffected by terrestrial weather conditions, thus enabling continuous operation. In all-sky interferometric meteor radar systems, amplitude and phase consistencies between multiple channels exhibit dynamic variations over time, which can significantly degrade the accuracy of wind measurements. Despite the inherently dynamic nature of these inconsistencies, the majority of existing research predominantly employs static calibration methods to address these issues. In this study, we propose a dynamic adaptive calibration method that combines normalized least mean square and correlation algorithms, integrated with hardware design. We further assess the effectiveness of this method through numerical simulations and practical implementation on an independently developed meteor radar system with a five-channel receiver. The receiver facilitates the practical application of the proposed method by incorporating variable gain control circuits and high-precision synchronization analog-to-digital acquisition units, ensuring initial amplitude and phase consistency accuracy. In our dynamic calibration, initial coefficients are determined using a sliding correlation algorithm to assign preliminary weights, which are then refined through the proposed method. This method maximizes cross-channel consistencies, resulting in amplitude inconsistency of <0.0173 dB and phase inconsistency of <0.2064°. Repeated calibration experiments and their comparison with conventional static calibration methods demonstrate significant improvements in amplitude and phase consistency. These results validate the potential of the proposed method to enhance both the detection accuracy and wind inversion precision of meteor radar systems. [ABSTRACT FROM AUTHOR]

Inspired by the biological eye movements of fish such as pipefish and sandlances, this paper presents a novel dynamic calibration method specifically for active stereo vision systems to address the challenges of active cameras with varying fields of view (FOVs). By integrating static calibration based on camera rotation angles with dynamic updates of extrinsic parameters, the method leverages relative pose adjustments between the rotation axis and cameras to update extrinsic parameters continuously in real-time. It facilitates epipolar rectification as the FOV changes, and enables precise disparity computation and accurate depth information acquisition. Based on the dynamic calibration method, we develop a two-DOF bionic active camera system including two cameras driven by motors to mimic the movement of biological eyes; this compact system has a large range of visual data. Experimental results show that the calibration method is effective, and achieves high accuracy in extrinsic parameter calculations during FOV adjustments. [ABSTRACT FROM AUTHOR]

In this study, a method is proposed to deal with the variable light conditions in a greenhouse to non-destructively predict the soluble solid content (SSC) of tomatoes on the plant. It was investigated how well the SSC – measured as °Brix – of tomatoes could be predicted based on spectral data in the range of 470–900 nm, where data acquired in situ (in the greenhouse) was compared to post-harvest data captured under controlled laboratory conditions. To deal with the variation in illumination in the greenhouse, a dynamic-calibration method is proposed, using a grey reference in the image. Ground-truth SSC data of the tomatoes was acquired using a refractometer. Data was collected of three different types of truss tomatoes with a wide range of SSC. Different PLS regression models were then trained on the spectral data in relation to the refractometer values. Trained and tested on all types, the in situ measurements showed a predicted coefficient of determination on the test set, Q2, of 0.95 with a Root Mean Squared Error of Prediction (RMSEP) of 0.29 °Brix using the dynamic calibration, and a Q2 of 0.93 with RMSEP of 0.35 °Brix without using the dynamic-calibration method. The post-harvest measurements resulted in a Q2 of 0.95 with RMSEP of 0.31 °Brix. The results show that spectral imaging using dynamic calibration is applicable for in situ non-destructive prediction of SSC. This method enables high-throughput and non-destructive quality estimation of fruits on the plant in commercial greenhouse conditions. • Vis-NIR spectral imaging compared between lab and greenhouse conditions. • Prediction of SSC based on PLS models trained on spectral imaging data. • Calibration of spectral data enables accurate SSC prediction under changing illumination. • Performance analysis of soluble solid content in tomato using spectral imaging. [ABSTRACT FROM AUTHOR]

To improve the shortcomings of the classic Black-Scholes model, mainly on the constant volatility and normal distribution assumptions, this paper investigates the dynamic calibration method, which makes the expected return rate, volatility and interest rate become data-driven and time dependent. Based on the dynamic procedure, four distinct calibration models are proposed by using Bayesian method, among which Model I and Model II are used for comparison, Model III simultaneously uses the data of underlying asset, put and call options by introducing the bivariate normal distribution, and Model IV simplifies Model III by employing the put-call parity. The results of numerical experiments and empirical analysis illustrate that Model III is the most accurate but time consuming, while Model IV is the most efficient. Dynamic calibration method is also verified to be much more accurate in data fitting and option pricing than the commonly used global calibration. Overall, the dynamically calibrated Black-Scholes model can be regarded as an improvement on the classic Black-Scholes model, where model coefficients are functions of time. As a result, leptokurtic and negative skew distribution of log returns is regenerated, which makes the model more consistent with the data observed in real markets without an increase of the complexity.

Purpose: This paper aims to propose an effective dynamic calibration and compensation method to solve the problem that the statically calibrated force sensor would produce large dynamic errors when measuring dynamic signals. Design/methodology/approach: The dynamic characteristics of the force sensor are analyzed by modal analysis and negative step dynamic force calibration test, and the dynamic mathematical model of the force sensor is identified based on a generalized least squares method with a special whitening filter. Then, a compensation unit is constructed to compensate the dynamic characteristics of the force measurement system, and the compensation effect is verified based on the step and knock excitation signals. Findings: The dynamic characteristics of the force sensor obtained by modal analysis and dynamic calibration test are consistent, and the time and frequency domain characteristics of the identified dynamic mathematical model agree well with the actual measurement results. After dynamic compensation, the dynamic characteristics of the force sensor in the frequency domain are obviously improved, and the effective operating frequency band is widened from 500 Hz to 1,560 Hz. In addition, in the time domain, the rise time of the step response signal is reduced from 0.29 ms to 0.17 ms, and the overshoot decreases from 26.6% to 9.8%. Originality/value: An effective dynamic calibration and compensation method is proposed in this paper, which can be used to improve the dynamic performance of the strain-gauge-type force sensor and reduce the dynamic measurement error of the force measurement system. [ABSTRACT FROM AUTHOR]

A one-component strain gauge dynamometer with a force measurement range of 0–0.33 N was developed and manufactured at the N. E. Zhukovsky Central Aerohydrodynamic Institute, to measure the unsteady friction force of the boundary layer on the wind tunnel walls at remarkably high Reynolds numbers. The static and dynamic characteristics of the dynamometer and its systematic errors were also investigated. The effects of the temperature, longitudinal, normal, and lateral forces, as well as the position of the longitudinal force application, were analyzed during the calibration. A block was designed and manufactured to calibrate the dynamometer using dead weights in a wind tunnel. Special experiments were performed in laboratory conditions to determine the friction force acting on the block axis. The developed dynamometer represents a dynamic system with its natural frequency of oscillations. The correction for the dynamics of the dynamometer is suggested on the basis of the method developed earlier. The mass of the metric part of the dynamometer, its natural oscillation frequency in the absence of damping in the direction of measuring the friction force, and the damping coefficient were determined to calculate the correction. The correction is verified by experiment with the application of a stepwise force. The effect of static and dynamic temperature components (the influence of the average temperature value and its change over time, respectively) on dynamometer readings was investigated. Corrections are proposed to eliminate the systematic errors due to the effect of temperature based on the previously developed method. Results revealed that the lateral force does not affect the dynamometer readings, while the effect of the normal force is 1.1% of the sensitivity coefficient of the longitudinal force. The temperature sensitivity of the sensitivity coefficient of the dynamometer is 0.017%/°C. The total measurement uncertainty of the friction force dynamometer was estimated as the standard deviation of the measurement results from the average value not exceeding 0.076% of the measurement range, and the relative uncertainty of the sensitivity coefficient is not more than 0.03%. The measurement uncertainty of the unsteady friction force will not exceed 0.86% of the dynamometer range with natural oscillations of the sensitive element. The developed single-component strain gauge dynamometer can be used to determine the friction coefficient of the boundary layer on a flat surface. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Shanghai Jiaotong University (Science) is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Portable recording equipment for law enforcement plays a key role in the law enforcement process of evidence, but because it is worn on the body, the recorded video shakes seriously, which affects the subsequent viewing and processing. In order to improve the anti-shake effect of portable recording equipment for law enforcement, a scheme combining two-axis mechanical anti-shake and video anti-shake was proposed. At the same time, a dynamic calibration scheme was proposed to improve the stability of anti-shaking effect of law enforcement instrument in complex environment. In order to solve the IMU data distortion problem caused by the restriction of collision to the two-axis mechanical anti-shake of the instrument, a fast recovery scheme was proposed.

This paper proposes two ways to improve pressure measurement in air-blast experimentations, mostly for close-in detonations defined by a small-scaled distance below 0.4 m.kg−1/3. Firstly, a new kind of custom-made pressure probe sensor is presented. The transducer is a piezoelectric commercial, but the tip material has been modified. The dynamic response of this prototype is established in terms of time and frequency responses, both in a laboratory environment, on a shock tube, and in free-field experiments. The experimental results show that the modified probe can meet the measurement requirements of high-frequency pressure signals. Secondly, this paper presents the initial results of a deconvolution method, using the pencil probe transfer function determination with a shock tube. We demonstrate the method on experimental results and draw conclusions and prospects. [ABSTRACT FROM AUTHOR]

This study investigated the dynamic characteristics of thermocouples by using double-pulse laser excitation for dynamic temperature calibration under extreme conditions. An experimental device was constructed for double-pulse laser calibration; the device uses a digital pulse delay trigger to precisely control the double-pulse laser to achieve sub-microsecond dual temperature excitation with adjustable time intervals. The time constants of thermocouples under single-pulse laser excitation and double-pulse laser excitation were evaluated. In addition, the variation trends of thermocouple time constants under different double-pulse laser time intervals were analyzed. The experimental results indicated that the time constant increases and then decreases with the decrease in the time interval of the double-pulse laser. A method for dynamic temperature calibration was established for the evaluation of the dynamic characteristics of temperature sensors. [ABSTRACT FROM AUTHOR]

• A high-speed heat flux dynamic calibration platform based on a semiconductor laser. • A finite element simulation analysis of a Gardon gauge was carried out. • Experiments are performed and compared with simulation results to obtain conclusions. • A reference for dynamic calibration of heat flow sensors using laser methods. In order to make the circular foil heat flux sensor meet the growing demand for dynamic heat flux monitoring in extreme environments such as hypersonic wind tunnels, a dynamic calibration platform with a high-power semiconductor laser as heat flux source is built. Combining Finite Element Analysis (FEA) and experiments to carry out relevant studies. Our findings indicate a negative correlation between the time constant and laser power/pulse width, whereas the rise time is positively correlated with the laser pulse width. And they are all positively correlated with the coating thickness. Importantly, FEA revealed the independence of laser parameters from the time constant. Additionally, when the laser pulse width is approximately one order of magnitude less than the time constant of the sensor, it can be deemed an ideal pulse excitation. In the experiment, the maximum heat flow density was applied up to 3.49 MW/m2, the minimum ideal pulse laser width can reach 1ms, the minimum time constant was measured to be 63 ms, and the minimum rise time was 12 ms. This research serves as a valuable reference for dynamically calibrating sensors using the laser method. [ABSTRACT FROM AUTHOR]

In this paper, we present an experimental setup developed for the calibration of dynamic force transducers which is based on the drop mass method. The traceability to SI units is realized through well-known mass characteristics and a reference shock accelerometer attached to that mass. Two approaches are proposed to analyse dynamic force employing a drop mass system. One approach depends on the inertial force of a falling mass while the other deals with the work-energy principle. Results of both approaches are then compared to the response of a statically calibrated force transducer. It is shown that the obtained maximum relative deviations between the response of force transducer and the first approach results are 1% while those of the second approach are 2%.

At the current stage, there is an urgent need for new techniques to dynamically calibrate advanced wide-range (up to 104 N~105 N) triaxial force transducers. Based on this background, this paper proposes a novel impact calibration method, specifically for the triaxial force transducer, with a wide range and high-frequency response. In this method, the Hopkinson bar, which is typically used to test the dynamic mechanical properties of materials, was used as a generator to generate reference input force for the transducer. In addition, unlike conventional methods, the transverse sensitivities of the transducer were given necessary importance in the proposed method. The calibration result of the triaxial force transducer was expressed in a sensitivity matrix, containing three main sensitivity coefficients and six transverse sensitivity coefficients. The least squares method (LSM) was used to fit the sensitivity matrix linearly. Calibration experiments were performed on a typical triaxial force transducer. Several key issues, involving the validity and the test range, of the method were further investigated numerically. The feasibility and validity of the method were eventually confirmed. The test range of the method can be up to 106 N. [ABSTRACT FROM AUTHOR]

Research in the field of dynamic torque calibration has gained some momentum in the last few years. At PTB, a calibration device for small dynamic torque levels up to about 0.5 N⋅m proved the working principle of dynamic torque calibrations with sinusoidal excitation. In a next step, a new calibration device was developed with the intention of generating higher dynamic torque levels in the range of up to 20 N⋅m. Although this is still less than many industrial applications require, it could pave the way to higher torque levels. The new calibration device features a horizontal arrangement of all components of the drive shaft. The device consists mostly of industrial components that have been modified, rather than custom-made components. After commissioning, optimising the device enabled a frequency range from 10 Hz to up to 400 Hz with dynamic torque amplitudes of up to 20 N⋅m.

In the dynamic techniques for calibration of triaxial accelerometers, the sensor is held in motion during data acquisition; the acquired time-varying acceleration is in general more informative than the constant acceleration acquired in static calibration approaches. Dynamic methods, however, typically require complex and expensive calibration setups based on high-precision moving benches, to guarantee accurate a-priori knowledge of the acceleration applied to the sensors under test. This article presents a dynamic calibration procedure working with a very simple and inexpensive setup: a tilted, freely-rotating bench, made of a simple wheel mounted on a static support. The accelerometer is fastened to the bench, which is then manually set into rotation; the acceleration signal is then acquired while the bench is freely rotating. No a-priori knowledge is required about the bench rotation: the proposed calibration procedure estimates both the calibration parameters and the bench motion. To keep the setup as simple as possible, an effort has been made to minimize also the necessity of prior knowledge of the bench geometry: only the distance of the sensor from the rotation axis needs to be known, which can be easily obtained through direct measurement on the bench. The proposed calibration has been tested both on synthetic data, to prove the absence of estimation biases and to evaluate the potential accuracy of the estimated parameters, and on real data from a MEMS triaxial accelerometer, to assess the practical usability and measure the actual precision of the procedure. [ABSTRACT FROM AUTHOR]

Accurate time-resolved force measurements for complex experimental systems are important for minimizing erroneous and misleading data. These measurements become difficult when a natural frequency of the system is in or near the expected frequency domain of the time-varying force being applied. In the cases where it is not possible to avoid this occurrence, the experimenter typically abandons the setup. This work presents an inverse filter method to compensate for the dynamic response of the measurement system. A two degree-of-freedom measurement system is used to obtain force measurements with dominant forcing frequencies above and below the first natural frequency of the system. The results show that inverse filtering can be used along with digital low pass filters to correct amplification and phase shift due to the dynamic response of the measurement system to within ±4.0 % of total forcing amplitude and ±5.0∘. A simple cam follower mechanism is proposed as a method of low-frequency dynamic testing. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Pressure sensors are frequently used for dynamic pressure measurements but are mostly calibrated by static methods. This is done due to the insufficient availability of dynamic calibration methods. One approach to overcome this lack is shown in this paper. The developed calibration device is a pistonphone based exciter to calibrate the frequency response of common pressure sensors. The first section disuses the principle of operation of the exciter. The following chapters show the evaluation of the uncertainty of measurement. First all effects are named while few effects are highlighted in detail. The paper closes with the final outcome of the uncertainty of measurement.

Research in the field of dynamic torque calibration has gained some momentum in the last few years. At PTB, a calibration device for small dynamic torque levels up to about 0.5 N m proved the working principle of dynamic torque calibrations with sinusoidal excitation. In a next step, a new calibration device was developed with the intention of generating higher dynamic torque levels in the range of up to 20 N m. Although this is still less than many industrial applications require, it could pave the way to higher torque levels. The new calibration device features a horizontal arrangement of all components of the drive shaft. The device consists mostly of industrial components that have been modified, rather than custom-made components. After commissioning, optimising the device enabled a frequency range from 10 Hz to up to 400 Hz.

In this paper, a sinusoidal pressure loading device based on static pressure and temperature is introduced for the use of dynamic calibration and testing of the pressure measurement system with transmission pipe. The device can generate a sinusoidal pressure from 1 kPa to 10 kPa under the static pressure no more than 1 MPa and frequency within (20–1000) Hz, meanwhile dynamic sinusoidal pressure loading can be carried out within (20–400) °C. And then the dynamic calibration of transmission tube under actual conditions can be simulated.

In vibration tests, the behavior of the structure depends on its mechanical boundary conditions, which are represented in physical tests by connecting elements with mechanical properties. Adjustable impedance elements are machine elements fulfilling the task of an adjustable connection on a vibration test bench and therefore represent a variety of properties. Their mechanical properties must be known over wider ranges than comparable compliant structures tested in the literature. This paper is dedicated to vibration testing of the adjustable impedance elements themselves, taking the influences of fixtures and measuring devices of the test bench into account. Different approaches for measuring the frequency response functions are applied to freely vibrating masses at a hydraulic and an electrodynamic test bench. Mass cancellation and the frequency-dependent measurement systems function have shown their usefulness in characterizing the biodynamic response of hand–arm models before. This measurement method is extended to be transferable to machine elements to obtain reliable results under a wider range of test conditions. The necessity for dynamically calibrated measurement of the frequency response functions is demonstrated for different free vibration masses and for two compliant elements on two different test benches to provide results over a wide range of test conditions. [ABSTRACT FROM AUTHOR]

An automatic navigation system was developed to realize automatic driving for combine harvester, including the mechanical design, control method and software design. First of all, for the harvester modified with the automatic navigation system, a dynamic calibration method of the rear wheel center position was proposed. The control part included the navigation controller and the steering controller. A variable universe fuzzy controller was designed to the navigation controller, which used fuzzy control to change the fuzzy universe of input and output dynamically, that means, under the condition that the fuzzy rules remain unchanged, the fuzzy universe changes with the change of input, which is an adaptive fuzzy control method and can modify the control strategy in time. To realize the automatic navigation of the harvester, the decision result of the navigation controller based on the variable universe fuzzy control was input into the steering controller, and then the electric steering wheel was controlled to rotate. To test the performance of the designed automatic navigation system, the experiments were carried out. When the combine harvester was navigating linearly at a speed of 0.8 m/s, the overall root mean square error (RMSE) of the lateral deviation was 5.87 cm. The test results showed that the system was designed could make the combine track the preset path smoothly and stably, and the tracking accuracy was at the centimeter level. [ABSTRACT FROM AUTHOR]

Settling time is an important performance metric in digital-to-analog converters (DACs) that are used for dynamic calibration applications. To obtain an area efficient DAC design, periodic sequences are generated from sigma-delta modulators (ΣΔMs) using software, stores the sequence in memory and then passes it to a low-pass filter (LPF). In this brief, the sigma-delta (ΣΔ) bitstream generated in software will be optimized such that it yields a system that settles faster and is more area efficient. Two optimization routines are used, namely, serial method and random method algorithms. The random method is chosen to optimize the ΣΔ bitstreams for its computational simplicity. It will be shown, that using the random method routine provides at least 46% improvement in settling time performance of a 12-bit DAC, used in the paper as a design example. Moreover, it offers silicon area savings by at least 10% for resistor components and 35% for capacitor components. Similar results were obtained for 8 to 11 bits of resolution.

In this paper, we present an experimental setup developed for the calibration of dynamic force transducers which is based on the drop mass method. The traceability to SI units is realized through well-known mass characteristics and a reference shock accelerometer attached to that mass. Two approaches are proposed to analyse dynamic force employing a drop mass system. One approach depends on the inertial force of a falling mass while the other deals with the work-energy principle. Results of both approaches are then compared to the response of a statically calibrated force transducer. It is shown that the obtained maximum relative deviations between the response of force transducer and the first approach results are 1% while those of the second approach are 2%. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Test & Measurement Technology is the property of Publishing Center of North University of China and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to reveal the dynamic response characteristic of thin film thermocouples (TFTCs), the nichrome/nisil (NiCr/NiSi) TFTCs are prepared onto the glass substrate. With short pulse infrared laser system, NiCr/NiSi TFTCs are dynamically calibrated. The thermoelectric electromotive force (TEF) curves of NiCr/NiSi TFTCs are recorded by the memory hicorder system, which could reflect TEF signals with resolution ratio in nanosecond and microvolt, simultaneously. With increasing laser energy from 15.49 to 29.59 mJ, TEF curves display more and more violent oscillation, even negative value. The results show that the bounce of thermal energy happens between two interfaces of TFTCs because the thermal conductivity of glass and air is significantly lower than that of NiSi/NiCr TFTCs. The bounce of thermal energy results in the obvious decrease of n NiCr and n NiSi , as well as oscillation of TEF. For laser energy in 29.59 mJ, the bounce of thermal energy in NiCr film could result in n NiCr < n NiSi . Then, TEF value appears abnormal negative value. Based on the results, the complex thermal energy transport process in TFTCs dynamic calibration is revealed, which results in the oscillation of thermal energy and TEF signal., (© 2023 Wiley‐VCH GmbH.)

Abstract It is difficult to measure infrared radiation quantitatively for fast dynamic targets such as aircraft and missile. At present, there are many problems such as low measurement accuracy, feedback delay, and complex measurement system. In this paper, a radiation measurement scheme based on image grayscale is proposed. The scheme adopts a two-dimensional turntable structure, which can measure the radiation quantity rapidly and accurately. Based on the image method, this method is used to calibrate the gray value of the target point and compare it with that of the absolute standard radiator, so as to obtain the radiation value of the target indirectly. The key of this method is to establish an accurate radiation measurement model. The proposed model based on dynamic calibration is about 50% more accurate than the traditional model. The final measurement accuracy of this model is 75%. Through the infrared radiation measurement of specific dynamic objects in two-dimensional space, it is found that the dynamic calibration model based on this measurement method has higher measurement precision.

In the paper, the optical system of a precise bar length measuring comparator is analysed. The requirements for such a system are determined and systematized. The impact of the resolution, signal discretization frequency, image blurring, bar edge measurement indeterminacy and camera noise on measuring the bar width and establishing the bar position is discussed upon. Various algorithms have been analysed and finally a bar edge identification algorithm oriented to the scale calibration accuracy and the high processing speed was proposed. In the end of the paper, conclusions are provided. [ABSTRACT FROM AUTHOR]

Copyright of Advanced Engineering Science / Gongcheng Kexue Yu Jishu is the property of Advanced Engineering Science Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this article, a piezoelectrically actuated flow excitation approach is presented for producing short rise time flow rate changes. This is a crucial requirement from flowmeter dynamic calibration. A single nozzle-flapper valve (NFV) is adopted as excitation flow generator. A commercially available piezo stack drives the flapper. Time-domain comparison between pressure difference across the reference restrictor and the indicated value of tested flowmeters in the circuit is made for the current dynamic performance of the tested flowmeter. Computational fluid dynamics (CFD) simulation is implemented for the pipeline system to investigate the excitation characteristics based on the dynamic pressure distribution. The experimental device is designed, using a turbine flowmeter in a fuel pipeline. The excitation experiments are conducted, with varying voltages applied to the piezo stack and fuel supply pressure. The experimental dynamic pressure in the control chamber agrees well with that obtained by CFD simulation. And the pressure gain on null position of the single NFV is slightly smaller than the theoretical value, whose correction factor is derived. This article demonstrates that a piezoelectrically actuated NFV can be effectively used in generating short rise time flow rate changes under different operating conditions, avoiding disturbance to the upstream flow field of the tested flowmeters. The flow excitation device is applicable to flowmeter dynamic calibration. [ABSTRACT FROM AUTHOR]

Copyright of Ordnance Industry Automation is the property of Editorial Board for Ordnance Industry Automation and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chinese Journal of High Pressure Physics is the property of Chinese Journal of High Pressure Physics Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The installation error of USBL acoustic transceiver array is one of the important error sources for the SINS/USBL integrated navigation system. The installation error of USBL transceiver array can be divided into coordinate shift error and angle rotation error. The angle rotation error (i.e., installation error angle) has a great influence on the positioning accuracy of USBL. In this paper, the traditional surround sailing method is used to study the relationship between the installation error angle and the USBL positioning accuracy. The influence on USBL positioning is analyzed from the component of heading, pitch, and roll of installation error angle, and the simulation results show that the horizontal positioning errors of USBL are mainly affected by the heading and rolling installation errors. The horizontal positioning error of USBL caused by heading or rolling installation error of 1° will result in 17.45 m, under the circumstance that the depth of transponder is 100 m and the radius of surround sailing is 1000 m, without considering the influence of other positioning errors. 1.75 m horizontal positioning error of USBL caused by pitching positioning error of 1° pitching positioning error and the horizontal positioning error of USBL caused by heading and pitching positioning error is also related to the horizontal distance between the transmitter and transponder. A dynamic calibration algorithm of installation error angle based on incremental iteration is proposed in this paper, which could realize the dynamic on-line estimation of installation error angle of USBL transceiver array. The installation error angle increment module can accurately estimate the installation angle error by iterating more than 10 times. In the case of ignoring the other error terms, the horizontal positioning error caused by the installation error angle can be reduced from 8 to 2 m in the positioning range of 1000 m.

In vibration tests, the behavior of the structure depends on its mechanical boundary conditions, which are represented in physical tests by connecting elements with mechanical properties. Adjustable impedance elements are machine elements fulfilling the task of an adjustable connection on a vibration test bench and therefore represent a variety of properties. Their mechanical properties must be known over wider ranges than comparable compliant structures tested in the literature. This paper is dedicated to vibration testing of the adjustable impedance elements themselves, taking the influences of fixtures and measuring devices of the test bench into account. Different approaches for measuring the frequency response functions are applied to freely vibrating masses at a hydraulic and an electrodynamic test bench. Mass cancellation and the frequency-dependent measurement systems function have shown their usefulness in characterizing the biodynamic response of hand–arm models before. This measurement method is extended to be transferable to machine elements to obtain reliable results under a wider range of test conditions. The necessity for dynamically calibrated measurement of the frequency response functions is demonstrated for different free vibration masses and for two compliant elements on two different test benches to provide results over a wide range of test conditions.

Dynamic calibration was performed in the laboratory on two catching-type drop counter rain gauges manufactured as high-sensitivity and fast response instruments by Ogawa Seiki Co. Ltd. (Japan) and the Chilbolton Rutherford Appleton Laboratory (UK). Adjustment procedures were developed to meet the recommendations of the World Meteorological Organization (WMO) for rainfall intensity measurements at the one-minute time resolution. A dynamic calibration curve was derived for each instrument to provide the drop volume variation as a function of the measured drop releasing frequency. The trueness of measurements was improved using a post-processing adjustment algorithm and made compatible with the WMO recommended maximum admissible error. The impact of dynamic calibration on the rainfall amount measured in the field at the annual and the event scale was calculated for instruments operating at two experimental sites. The rainfall climatology at the site is found to be crucial in determining the magnitude of the measurement bias, with a predominant overestimation at the low to intermediate rainfall intensity range.