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According to the characteristics of stable single-phase flow, a phase difference measurement method based on the extended Kalman filter is proposed in this paper for use with Coriolis mass flowmeters. Firstly, the Mallat algorithm is applied to filter out interference signals. Then, the frequency and phase difference of the two reconstructed signals are detected through the extended Kalman filter. Compared with the sliding Goertzel algorithm or discrete time Fourier transform, the proposed method does not need to predict the signal frequency and avoids quadratic error. Simulations and experiments show that the proposed method has stronger anti-interference, higher measurement accuracy and lower relative error than the existing method based on the Hilbert transformation.

In the oil industry, the accompanied reverberation is a major constraint in the transmission rate and distance because the drillstring is a heterogeneous assembly. Based on the transient impulse responses in uplink and downlink channels, an improved simplified echo suppression model with two acoustic receivers is presented in consideration of position optimization of single acoustic receiver. Then the acoustic receiving characteristics of transmitted signals in a length-limited periodic drillstring channel are obtained in single- and dual-receiver modes. An additive downward white Gaussian noise is also introduced in the channel. Moreover, an experimental rig is established by using a rotatable electromagnetic vibration exciter and two piezoelectric accelerometers, which are spaced one-quarter wavelength apart along a 6.3-meter simulated periodic drillstring. The ASK-, FSK-, and PSK-modulated square-wave pulse sequences at a transmission rate of 200 bit/s are applied to the simulated drillstring at a rotation speed of 0, 80, and 140 r/min, respectively. The experimental results show that the dual-receiver mode can exhibit a significantly improved average error bit ratio, which is approximately 2.5 to 3 times lower than that of the single-receiver mode, especially under the conditions of higher rotation speeds.

A new method of wireless data telemetry used by oil industry uses compressional acoustic waves to transmit downhole information from the bottom hole to the surface. Unfortunately, acoustic echoes and drilling vibration noises in periodic drillstring are a major issue in transmission performance. A combined acoustic echo and noise suppression method based on wave motion characteristic in drillstring is adopted to enhance an upward-going transmitted acoustic signal. The presented scheme consists of a primary acoustic echo canceller using an array of two accelerometers for dealing with the downward-going noises and a secondary acoustic insulation structure for restraining the upward-going vibration noises. Furthermore, the secondary acoustic insulation structure exhibits a banded and dispersive spectral structure because of periodic groove configuration. By using a finite-differential algorithm for the one-dimensional propagation of longitudinal waves, acoustic receiving characteristics of transmitted signals are simulated with additive Gaussian noise in a periodic pipe structure of limited length to investigate the effects on transmission performance optimization. The results reveal that the proposed scheme can achieve a much lower error bit ratio over a specified acoustic isolation frequency range with a 30–40 dB reduction in the average noise level compared to traditional single-receiver scheme.

Coriolis mass flowmeter (CMF) measures the mass flow rate by detecting the time difference, typically using frequency domain methods. However, the spectrum leakage is the primary challenge. To address this issue, a new time difference detection method is proposed utilizing sliding window and all-phase fast Fourier transform. The computational complexity is reduced considering the changes in signal frequency. To further improve the stability and response speed of the measured value, a Kalman filtering algorithm based on variance detection is also proposed for post-processing. A transmitter system is developed to validate the proposed methods. The results demonstrate that, for single phase fluids, the accuracy is better than 0.5‰ and the repeatability is better than 0.2‰, thereby offering an improvement in the accuracy of CMF and supporting for industrial applications. [ABSTRACT FROM AUTHOR]

Micro/nano waveguide has been widely exploited for gas sensing due to its strong confinement of evanescent field, compact size, and fast response. However, the state‐or‐the‐art evanescent‐wave gas sensors still struggle to satisfy the requirements of high sensitivity, high selectivity, large dynamic range, and long‐term stability. In this work, microfiber‐based evanescent‐wave mode‐phase‐difference photothermal spectroscopy for trace gas detection is reported. With a microfiber of 5.6 cm in length and 2.36 µm in diameter, noise‐equivalent‐concentration of 160 ppb methane in nitrogen is achieved with a dynamic range over 6 orders of magnitude, response time of less than 6 s, and <3% instability over 7 days. The technique utilizes commercial fiber‐optic components to make cost‐effective lab‐on‐fiber probes with real‐time and remote detection capability for industrial, medical, and environmental monitoring. [ABSTRACT FROM AUTHOR]

Graphene resonant sensors have shown strong competitiveness with respect to sensitivity and size. To advance the applications of graphene resonant sensors, the damage behaviors of graphene harmonic oscillators after thermal annealing and laser irradiation were investigated by morphology analysis and frequency domain vibration characteristics. The interface stress was proven to be the key factor that directly affected the yield of resonators. The resulting phenomenon could be improved by appropriately controlling the annealing temperature and size of resonators, thereby achieving membrane intactness of up to 96.4%. However, micro-cracks were found on the graphene sheets when continuous wave (CW) laser power was more than 4 mW. Moreover, the fluctuating light energy would also cause mechanical fatigue in addition to the photothermal effect, and the threshold damage power for the sinusoidally modulated laser was merely 2 mW. In this way, based on the amplitude-frequency surface morphology of the graphene resonator, the thermal time constant of the order of a few microseconds was confirmed to evaluate the damage of the graphene oscillator in situ and in real time, which could be further extended for those resonators using other 2D materials. [ABSTRACT FROM AUTHOR]