SISTEMA ULTRASÓNICO PARA LA DETECCIÓN DE PUNTOS DE FUGA EN BOMBAS Y FILTROS DE GASOLINA AUTOMOTRICES

Low temperature drying process intensification by application of power ultrasound. Design and development of ultrasonic drying equipment and systems

A highly accurate multiple-frequency continuous wave ultrasonic range-measuring system for use in air is described. The proposed system uses a method heretofore applied to radio frequency distance measurement but not to air-based ultrasonic systems. The method presented here is based upon the comparative phase shifts generated by three continuous ultrasonic waves of different but closely spaced frequencies. In the test embodiment to confirm concept feasibility, two low cost 40 kHz ultrasonic transducers are set face to face and used to transmit and receive ultrasound. Individual frequencies are transmitted serially, each generating its own phase shift. For any given frequency, the transmitter/receiver distance modulates the phase shift between the transmitted and received signals. Comparison of the phase shifts allows a highly accurate evaluation of target distance. A single-chip microcomputer-based multiple-frequency continuous wave generator and phase detector was designed to record and compute the phase shift information and the resulting distance, which is then sent to either a LCD or a PC. The PC is necessary only for calibration of the system, which can be run independently after calibration. Experiments were conducted to test the performance of the whole system. Experimentally, ranging accuracy was found to be within ±0.05 mm, with a range of over 1.5 m. The main advantages of this ultrasonic range measurement system are high resolution, low cost, narrow bandwidth requirements, and ease of implementation.

In the industry it is very common for failures to occur in machinery and equipment such as poorly lubricated elements; friction between mechanical elements; gas or vacuum leaks in pressurized systems; and electric arcs in motors, transformers and electrical installations. Each of these faults emits ultrasound and can be detected early using an ultrasonic detector. The objective of this work is to present a proposal for the development of a system capable of opportunely detecting the ultrasound emitted by faults, which is very useful for predictive maintenance. The methodology consists of the development of a system that detects the ultrasound decibels emitted by the fault using an ultrasonic sensor of the last generation, and the necessary interfaces. Ultrasound decibels will increase exponentially in the presence of these flaws, allowing their detection. This document offers an alternative for the development of an ultrasonic system useful in predictive maintenance, which is within the reach of any company.

In Chap. 1 we saw that an ultrasonic system has many components. Those components individually can be complex electromechanical systems such as, for example, the ultrasonic transducers. To model each of the elements that go into an ultrasonic system and how they work together to produce a measured response is a challenging task, indeed. In this chapter we will present a very general modeling framework of linear time-shift invariant (LTI) systems which we will use in order to describe a complete ultrasonic NDE measurement system. Many of the remaining chapters will fill in the details of this general framework and ultimately produce an explicit LTI models of the entire ultrasonic measurement process.

A severe accident at TEPCO’s Fukushima Dai-ichi Nuclear Power Plant (FDNPP) occurred due to a strong earthquake and massive tsunami that struck Japan’s eastern region on 11 March 2011. During this accident, the reactor core of Units 1, 2, and 3 of the 1F melted and fuel debris formed in the reactor pressure vessel (RPV) and primary containment vessel (PCV). The Japanese Government has drawn a mid- and long-term roadmap towards 1F decommissioning. However, three reactors’ decommissioning work has faced difficulties due to the lack of realistic information about the damaged cores such as the distribution of fuel debris. Since the radiation levels inside the reactor buildings have been too high for human access, the robots and cameras have been using to investigate the internal status of PCV. To accelerate the decommissioning process of 1F, determining of fuel debris information and contaminated water leakage is crucial to decide further decommissioning steps and strategies. Therefore, in this study, we are developing an ultrasonic measurement system that can obtain object’s shape and the velocity around it. Because ultrasonic transducers are robust against high radiation dose and applicable in opaque liquids. The ultrasonic system used in the present study consists of two sectorial array transducers, which can measure object shape and 2D vector flow field. To measure the object’s velocity and shape that represents fuel debris, Ultrasonic Velocity Profiler (UVP) and Total Focusing Methods (TFM) are employed, respectively. Based on measurement results of the 2D vector field and shape of the object, we can predict contaminated water leakage and distribution of object at the bottom of the PCV in 1F.

In order to solve the problem that it is difficult to detect the local ice layer debonding when the thermal protection system is working, an on-line ultrasonic detection method for the melting degree of interface between skin and ice layer based on the theory of ultrasonic transmission in multi-layer media was studied. A multi-layer medium acoustic model including skin, water film, ice water transition layer, ice layer and air layer is constructed. Ultrasonic pulse waves with different center frequencies are used as excitation sources, and the echo signals of multi-layer medium interface are obtained by using the numerical calculation. The ultrasonic signal processing algorithm for ice melting and debonding measurement is developed. The original echo signal is processed and the characteristic parameters of the echo signal of interface between skin and ice layer are extracted. The ultrasonic reflection coefficient of interface between skin and ice layer is proposed to evaluate the degree of ice melting. The ultrasonic ice detection system was built, and the low-temperature ultrasonic sensor was designed and fabricated. The ability of the system to measure the degree of ice melting under the action of electric heating was verified in the low-temperature environment. The ultrasonic ice detection system was built, and the low-temperature ultrasonic sensor was designed and fabricated. The ability of the system to measure the degree of ice melting under the action of electric heating was verified in the low-temperature environment. The theoretical results show that when the ice on the skin melts and produces a thin water film, the degree of ice melting can be reflected by the change of ultrasonic reflection coefficient at the skin-attachment interface. In this paper, the ultrasonic reflection coefficient more than 0.8 is used as the criterion of ice melting. With the increasing of center frequency of the ultrasonic signal, the thinner water film can be identified. The identification thickness of the water film corresponding to 7.5 MHz center frequency signal is 10 μm. The experimental results show that under the conditions of clear ice, mixed ice and frost ice, the ultrasonic detection system can out-put the ice layer debonding signal at the initial stage of electric heating. The propagation characteristics of ultrasonic pulse wave of interface between skin and ice layer in the thermal protection are preliminarily explored. The present method for detecting the degree of ice melting is expected to further reduce the energy consumption of thermal protection.

Ultrasonic sensors for an energy-saving system

In factory manufacturing, pneumatic cylinder systems play a vital role in various operations. However, they are susceptible to air leaks, which can lead to significant inefficiencies and operational disruptions. This project introduces an innovative solution for real-time air leak detection in pneumatic cylinder systems, leveraging advanced flow sensors and Siemens PLC technology to enhance reliability and efficiency. The primary objective is to develop a sophisticated leak detection system specifically for pneumatic cylinders. The system employs flow sensors to continuously monitor airflow and instantly detect any deviations indicative of a leak. Upon detecting a leak, the system automatically halts the operation of the affected pneumatic cylinders. It activates an indicator light to alert maintenance personnel, consequently preventing further damage and loss of productivity. Key components of this project include the design and assembly of the leak detection hardware, the configuration and analysis of data from the flow sensors, and the development of a robust PLC program using Siemens PLCs to manage and control the leak detection process. Additionally, comprehensive installation guides and instructional videos are provided to facilitate user understanding and implementation. The development of this system follows the Software Development Life Cycle (SDLC) model, encompassing five critical phases: analysis, design, implementation, testing, and evaluation. Each phase was meticulously executed to ensure the system's accuracy and reliability, and extensive testing was conducted to validate the system's performance, confirming its ability to effectively detect and respond to air leaks in pneumatic cylinders. This research not only improves operational efficiency by minimizing air leak-related downtime but also contributes to the sustainability of manufacturing processes by reducing air wastage. Furthermore, the innovative integration of flow sensors and Siemens PLC technology sets a new standard for leak detection in pneumatic cylinder control systems.

This paper introduces the concept of ultrasonic venting. Similar to acoustic vents, ultrasonic vents refer to the aperture in air-coupled MEMS ultrasonic transducers (either PMUT or CMUT) intended to allow the equalization of internal and external pressures, the transfer of heat and the pass of ultrasonic waves, while impeding the penetration of fluids or particles that can affect the transducer membrane. To that end, vents are covered with a porous membrane whose properties are tuned to meet the afore mentioned requirements. The main difficulty in ultrasonic venting, compared with acoustic venting, is that the required “transparency” to ultrasonic waves is much more difficult to achieve. This involves two main problems as both transmission loss and frequency distortion are much larger at ultrasonic frequencies than in the audio range. The objectives of this paper are: to measure the response of acoustic venting materials in the ultrasonic frequency range, to determine the usability of these materials in ultrasonic vents, and to extract useful information for the design of efficient ultrasonic venting materials. Transmission coefficient spectra of different acoustic venting materials is measured in the frequency range 0.2 –2.7 MHz. The origin of the ultrasonic losses and frequency distortion are analysed as well as the role of mode conversion, internal interferences, modes interference, etc. Results reveal that none of the acoustic venting materials analysed can be used in ultrasonic venting applications, but the obtained knowledge about the response of these materials in the ultrasonic frequency range permit to advance in the selection of successful candidate materials for this application.

Ultrasonic gas flowmeters employ non-intrusive measurement techniques, characterized by rapid responsiveness and exceptional anti-interference capabilities. These attributes not only minimize disruption to the gas during measurement but also facilitate dynamic process control while ensuring robust performance under complex operational conditions. This paper provides an overview of the key components of ultrasonic gas measurement systems, briefly summarizing the fundamental principles of commonly used measurement methods. After focusing on the evolution of transducer structures and materials within ultrasonic probes, it categorizes different types of transducers and outlines the latest designs of excitation circuits in both hardware and software. The review also critically assesses the determination of echo signal reception characteristics and the accuracy and effectiveness of time-of-flight calculations. Based on innovative analyses of the critical nodes within the measurement system's components, a framework system is established for corresponding measurement scenarios. The measurement results show that the repeatability error of the new transducer remains below 0.3%. The optimized signal processing method expands the measurable flow range to 30–1200 m3/h, and the zero drift is reduced to approximately half of the system's original zero drift. This paper aims to provide clear guidance for researchers and professionals in related industries, enabling them to conduct more in-depth studies based on their research interest and enhancing their understanding of ultrasonic measurements.

11 - Ultrasonics

Pipelines are subject to wall-thickness loss due to corrosion along time. Ultrasonic pulse-echo techniques are widely used for thickness measurement achieving a high resolution. However, the precision of measurement is highly dependent on temperature and on the ultrasonic system. This work presents the temperature correction strategy of an ultrasonic measurement system to obtain one micron accuracy, in a pipeline corrosion long-lasting monitoring. The proposed technique is based on the fact that the coupling layer has a constant thickness during a long period of time (year) and can be used in the same way as a thermometer to compensate the changes in the ultrasonic velocity. The variation of time of flight in the coupling layer can relate to the variation of time of flight in the pipe wall to construct a correction polynomial. This function compensates the variation on propagation velocity and thermal expansion. The results are experimentally evaluated using an array of eight ultrasonic transducers (5 MHz, 10-mm diameter) operating in pulse-echo mode with a water coupling layer. Long term corrosion tests were conducted using an electrolytic bath along ten months. Good agreement was found between the theoretical corrosion rate and the results of the ultrasonic measuring system.

A measurement system which characterizes the reverberations occurring in medical ultrasound (US) images has been developed. Reverberations cause multiple copies of anatomical structure interfaces, degrading image quality, accuracy and leading to potential misdiagnosis. The system is suitable for characterizing the reverberations during design phase of US probes and for investigating the root causes of these distortions that influence the medical images. The system, based on non-destructive evaluation of the materials, is implemented by means of an ad hoc measurement chain, in which a silicone membrane specially designed to generate reverberations, replicates the same acoustic properties of human skin. The experimental setup based Time of Flight (ToF) of the echoes allows for detecting the reverberation source in the US probe acoustic stack. The proposed quantitative approach can help to predict US probe performances during design stage becoming very useful during imaging validation. Accurate description of the ultrasonic transmit-receive measurement system is discussed by taking into account different material, geometry and thickness of the layers involved in the US probe. Experimental results show that the implemented system can detect the root cause of reverberations by accurately quantifying the layer source providing imaging distortion.

This paper presents an unrestrained measurement system based on a wearable wireless ultrasonic sensor network to track the lower extremity joint and trunk kinematics during a squat exercise with only one ultrasonic sensor attached to the trunk. The system consists of an ultrasound transmitter (mobile) and multiple receivers (anchors) whose positions are known. The proposed system measures the horizontal and vertical displacement, together with known joint constraints, to estimate joint flexion/extension angles using an inverse kinematic model based on the damped least-squares technique. The performance of the proposed ultrasonic measurement system was validated against a camera-based tracking system on eight healthy subjects performing a planar squat exercise. Joint angles estimated from the ultrasonic system showed a root mean square error (RMSE) of 2.85° ± 0.57° with the reference system. Statistical analysis indicated great agreements between these two systems with a Pearson's correlation coefficient (PCC) value larger than 0.99 for all joint angles' estimation. These results show that the proposed ultrasonic measurement system is useful for applications, such as rehabilitation and sports.

Leak detection in nuclear reactor coolant systems is crucial for maintaining the safety and operational integrity of nuclear power plants. Traditional leak detection methods, such as acoustic emission sensors and spectroscopy, face challenges in sensitivity, response time, and accurate leak localization, particularly in complex piping systems. In this study, we propose a novel leak detection approach that incorporates a rigid guide tube into the insulation layer surrounding reactor coolant pipes and combines this with an advanced detection criterion based on Frequency Center of Gravity shifts and Signal-to-Noise Ratio analysis. This dual-method strategy significantly improves the sensitivity and accuracy of leak detection by providing a stable transmission path for ultrasonic signals and enabling robust signal analysis. The rigid guide tube-based system, along with the integrated criteria, addresses several limitations of existing technologies, including the detection of minor leaks and the complexity of installation and maintenance. By enhancing the early detection of leaks and enabling precise localization, this approach contributes to increased reactor safety, reduced downtime, and lower operational costs. Experimental evaluations demonstrate the system’s effectiveness, focusing on its potential as a valuable addition to the current array of nuclear power plant maintenance technologies. Future research will focus on optimizing key parameters, such as the threshold frequency shift (Δf) and the number of randomly selected frequencies (N), using machine learning techniques to further enhance the system’s accuracy and reliability in various reactor environments.