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Accurate measurement of suspended particle concentration in pipelines is essential for analyzing the fluid mixing density and particle settlement. However, measuring concentration distributions along the flow path poses significant challenges due to the inherent complexity and variability of liquid–solid two-phase suspensions. In this study, we developed a sensor measurement system based on multi-frequency acoustic emission technology and a self-receiving single probe. The effects of suspended particle size, concentration, and ultrasonic transducer dimensions on acoustic wave propagation were analyzed using the COMSOL Multiphysics system. For multi-frequency echo signals, variational mode decomposition and the sparrow search algorithm were employed to decompose and optimize the signal, followed by reconstruction using the Pearson correlation coefficient. By combining the energy ratio method with the minimum concentration difference method, we propose a new approach for simultaneous measurement of particle size and concentration along the pipeline transmission path. Experimental results indicate that along the transmission path, the mean absolute percentage error is 18.74%, and 77.55% of the predicted results exhibit relative errors below 20%. [ABSTRACT FROM AUTHOR]

In the urban canyon environment, the integer ambiguity is hard to be fixed completely mainly because of the multipath effects, hence partial ambiguity resolution (PAR) is developed. This paper systematically introduces a new model-driven PAR method considering elevation and C/N0. Firstly, the theory of partial ambiguity resolution, the elevation-C/N0 function, and the proposed elevation-C/N0 PAR method are deduced in detail. Secondly, the proposed elevation-C/N0 method is applied in the static and dynamic experiments. The performances of the proposed method are compared with the full ambiguity resolution method, traditional elevation-dependent method, and C/N0-dependent method. Comparisons indicate that the proposed elevation-C/N0 method outperforms other methods. The results show that no matter in the urban static experiment or the dynamic experiment, the ambiguity resolution and positioning solutions can be improved. [ABSTRACT FROM AUTHOR]

A new earth pressure sensor is constructed based on the inverted triangle and flat diaphragm slotted sensing structure, combined with Ultra Weak Fiber Bragg Grating sensing technology. The influence of earth pressure sensing element size, flat diaphragm thickness and slotted depth on the sensitivity and detection range of the sensor is studied in combination with ANSYS simulation theory, and the theoretical optimal preparation size of the earth pressure sensor is obtained. Based on the principle of flat diaphragm pressure sensing, the innovative pressure-strain sensitization theory of inverted triangular structure is proposed, which will substantially improve the sensitivity of the sensor. A small Ultra Weak Fiber Bragg Grating earth pressure sensor with a diameter of 40 mm and temperature compensation is designed, and the characteristics of the sensor are calibrated using a uniform mechanical loading method of gravity-sand layer-diaphragm. The results show that the sensitivity of the pressure sensor can reach 7.3 pm/KPa with a full scale range of 0.7 MPa, effectively eliminating the effect of temperature on the sensor, and can be connected in series with a distributed ultra-weak grating fiber optic cable to achieve point/distributed sensing. [ABSTRACT FROM AUTHOR]