查看更多>>摘要：? 2022 Elsevier LtdThe code-based method is a popular technique in fringe projection profilometry. However, the lens defocusing and ambient noise can cause the jump errors in the absolute phase. Furthermore, harsh measuring environments, such as global illumination, might aggravate the errors further. In this paper, a phase-based XOR coding strategy (PBXOR) is designed to settle the above problems simultaneously without additional patterns. Especially, the high-frequency characteristic of the wrapped phase is converted into a complementary pattern. By adopting a new coding method, the common low-frequency binary code is embedded with high-frequency information, which can suppress the errors caused by global illumination. Moreover, by utilizing the complementary pattern to optimize the decoding process, the defocusing errors are transferred from the edges of the coded patterns to their monochromatic regions, which are easy to eliminate. The results of the contrast experiments prove that PBXOR can effectively settle defocusing and global illumination.
查看更多>>摘要：? 2022 Elsevier LtdTo simultaneously balance the high accuracy of small displacement vibration measurement and the tracking robustness of large-scale rotational motion in structural dynamic testing, a tracking-detecting-deformable matching (TDDM) point tracking method is proposed in this paper. In this new method, the movement range of the target point is estimated through tracking, and then the drift and accumulated error of the tracker is corrected by real-time detecting. The tracking and detecting decision result is taken as the initial guess for matching, and the optimal local deformation correction is finally solved. The proposed method is first tested in the numerical experimental images with different interference terms to demonstrate its performance in challenging application scenarios. In addition, low amplitude vibration testing and large-scale rotational motion tracking cases are tested. The TDDM shows a much higher measurement accuracy and tracking success rate than the existing point-tracking-based vision measurement methods.
查看更多>>摘要：? 2022 The AuthorsDynamic compaction method (DCM) is currently one of the most commonly used foundation reinforcement techniques. However, manual monitoring is still the mainstream way of DCM tamping counting with low efficiency and high cost. This paper focuses on the tamping times of DCM, and proposes a non-contact Intelligent Monitoring Method for Tamping Times (IM2T2) based on machine vision and pattern recognition technology. The hammer detection methods based on cooperative targets, YOLOv4 and YOLOv4-tiny are compared, and then the motion model based on the hammer position of construction image series is proposed and the vision-based full automatic measurement of tamping times is realized. Moreover, a field test was carried out to verify the applicability of above method. The results of the tamping times measurement indicate that the proposed method can measure the count of tamping under general working conditions with quite high accuracy.
查看更多>>摘要：? 2022 Elsevier LtdA particle filtering (PF) is a sequential Bayesian filtering method suitable for non-linear non-Gaussian systems, which is widely used to estimate the states of parameters of interest that cannot be obtained directly but still relate to noisy measured data with probability masses. Possible values of targeted parameters (or particles) are sampled according to the related prior knowledge, with their probabilities (or weights) evaluated from the likelihood of being the true values of those parameters. However, most have negligible weights. The standard PF algorithm consists of three steps as particle generation, weight calculation or updating and particle regeneration, which is called resampling. The performance of PF depends greatly on the quality of particle regeneration. Resampling preserves and replicates particles with high weights, while those with low weights are eliminated. However, particle impoverishment is a side effect that reduces the diversity of particles used in the next time steps. Therefore, efficient resampling have to guarantee high likelihoods particles. This paper reviews the classification and qualitative descriptions of recent efficient particle weight-based resampling schemes and discusses their characteristics, implementations, advantages and disadvantages of each scheme.
查看更多>>摘要：? 2022 The Author(s)Measurements of surface luminance distribution have been applied as an innovative method for assessing intramuscular fat content in pork. A dedicated experimental setup has been developed to perform measurements with an LMK matrix luminance meter, based on a Canon camera and Sigma Gold lenses. A SINGLEPIC ALGORITHM incorporated into the meter has allowed us to convert RAW format images into luminance distribution images. Analysing the data obtained with a dedicated LMK LabSoft software, adapted to meet our research goals, allowed us to determine fat content with the luminance method. The Soxhlet chemical method has served as a reference. The experimental material consisted of 68 longissimus thoracis muscle samples. Under a comparative study the average intramuscular fat content in the tested samples was determined as 1.67% and 1.68% for the Soxhlet and luminance method, respectively. The correlation factor between both methods was equal to ρ = 0.79, p < 0.001. The experimental results have met our expectations, and the luminance measurement method has been proven to be a reliable experimental tool for assessing intramuscular fat content, providing an alternative to the conventional Soxhlet approach.
查看更多>>摘要：? 2022 The AuthorsAmplifiers are typically characterized upon narrow-band small-signal models, computed on multiple input signals. Standard figures of merit derive from those, but they do not easily match users’ data needs and are tedious to compute. Particularly for addressing wide frequency ranges and different operating points. We present a rapid and robust procedure to characterize amplifiers nonlinear behavior attending to a projection of Volterra kernels onto their diagonals. It addresses separately nonlinear and linear effects from a single swept excitation. Output may be used to compute standard figures and an informed wide-band extended characterization on amplitude and phase that unveils the system continuous nonlinear response. Procedure is tested on a commercial amplifier, comparing standard figures computed on the proposed method and a conventional one involving multiple, multi-tone input signals. Results validate standard figures computation and evidence the added value of this method, regarding speed and additional information provided.
查看更多>>摘要：? 2022 Elsevier LtdLearning how to reconstruct the magnetic field profile from the pulsed wire method (PWM) is of fundamental importance to characterize undulators with limited magnetic gap accessibility. This paper presents a new data processing approach to reconstruct undulator magnetic field profiles from the PWM. We study via numerical simulations the accuracy and precision of the novel approach to recover the local undulator parameter and the root-mean-square (RMS) phase error. Due to the wire parameters uncertainties, the PWM can, in the best case, reach an accuracy of approximately 10?3 to reconstruct the local undulator parameter, and a precision (needed to determine the magnetic field quality) of about 10?5. Furthermore, our results show that the RMS phase error can be determined with a precision better than 0.2°. This contribution opens the possibility to apply the PWM to perform magnetic field reconstruction in small-gap short-period long undulators for advanced light sources.
查看更多>>摘要：? 2022 Elsevier LtdThis paper presents an innovative measurement method for a two-phase fuel transient flow rate in the same space–time dimension. Based on the jet momentum measurement, a spray filter is designed to realize the space extraction of the target jet. The optimized jet baffle structure is proposed, which greatly improves the quality of the test signal. Compared with the pressure–time method, this method has higher precision in the gas injection rate shape measurement and the recognition precision of gas injection beginning and ending moment. The coupling effect of two-phase fuel injection and the influence of different ambient pressures on injection performance can be studied by this method. The results show that the pilot diesel injection will cause more than 20% fluctuation of gas injection mass, and the ambient pressure can promote the gas needle opening, which will significantly affect the fuel injection mass of the engine.
查看更多>>摘要：? 2022SINS/GPS integrated systems are influenced by non-Gaussian noise and unknown measurement noise due to exogenous disturbances and inaccurate noise statistics. To overcome this problem, a robust variational Bayesian method-based SINS/GPS integrated system is designed. First, the variational Bayesian-based Kalman filter is selected to estimate unknown measurement noise covariance. Second, the maximum correntropy criterion is introduced to the nonlinear robust filter to handle interference from non-Gaussian noise. Finally, the robust variational Bayesian method is designed based on the interacting multiple model, which not only fuses the variational Bayesian-based Kalman filter and the robust filter but also avoids non-Gaussian noise interference to the estimation result of measurement noise covariance. The robustness and adaptivity of the robust variational Bayesian method are verified by numerical simulation. Furthermore, the flight test results show improved performance of the SINS/GPS integrated system using the proposed method.
查看更多>>摘要：? 2022 Elsevier LtdCondition monitoring in the water distribution network and sewerage pipelines is one of the primary concerns for water utility companies. The impact of complex interconnected parameters on pipe deterioration mechanisms, lengthy water transmission networks and resource utilisation makes maintenance procedure more challenging. Various condition monitoring techniques for underground water pipes are in practice by water utility companies. High resolution cameras, electromagnetic waves, laser radiation, ultrasonic waves, acoustic sensors, eddy current and thermal profiling methods are used for condition assessment. However, these technologies also have limitations depending on pipe material, size of pipe, types of defects, environmental factors, size of pipe network, water pressure and flow rates. The current review includes a wide range of condition monitoring techniques for water pipelines and also highlights key features and limitations of emerging techniques.
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