A Simulation Framework for Passive Acoustic Thermometry of Nonhomogeneous Materials

Purpose: Internal temperature is a significant factor for medical diagnosis. There are several thermometric methods, including IR, MRI, and active ultrasonic thermometry, which have limitations for clinical applications. The new method in this field called Passive Acoustic Thermometry (PAT), which enhanced some of this limitation. PAT is a safe method for internal temperature estimation that works based on acoustic radiation of materials with a specific temperature. Several experimental studies have been carried out so far in the field of PAT. While, to the best of our knowledge, there is no simulation-based research for nonhomogeneous materials reported yet. In this article (for the first time) we proposed a simulation framework for evaluating the PAT methodologies in nonhomogeneous materials; also we proposed a new formulation for temperature estimation in PAT algorithm. Materials and Methods: This framework supports the generation of acoustic radiation, signal processing, parameter estimation, and temperature reconstruction processes. At the moment the proposed framework estimates the temperature in the frequency domain and uses the frequency spectrum of the acquired ultrasound signals captured by a single transducer. Using the proposed framework, we tried to implement the previously practical experiments and the results of the simulation are consistent with those of the practical experiments. Also, we proposed the formulation that improves the error of temperature estimation. Results: We study 6 scenarios, including 2 environments with a target at 3 different temperatures. The average error of the proposed formulation in two different nonhomogeneous materials for three different temperatures is less than 0.25°C. Conclusion: The results show that the proposed formulation is the best estimation in the formula that has been introduced until now and compare with the previous study the accuracy is enhanced 54% (from 0.79 to 0.36 deg.). Therefore, the proposed formula enhanced PAT accuracy for temperature estimation. Also, the results show that it is possible to use this framework to evaluate the PAT in different scenarios. Therefore, this method enhances the possibility of examination of different conditions and algorithms. It also reduces the cost of practical experiment.

Implementation of a multipurpose Arctic Ocean Observing System

<p>The central Arctic Ocean is one of the least observed oceans in the world. This ice-covered region is challenging for ocean observing with respect to technology, logistics and costs. Many physical, biogeochemical, biological, and geophysical processes in the water column and sea floor under the sea ice are difficult to observe and therefore poorly understood. Today, there are technological advances in platforms and sensors for under-ice observation, which offer possibilities to install and operate sustained observing infrastructures in the Arctic Ocean. The goal of the INTAROS project is to develop integrated observing systems in the Arctic, including improvement of data sharing and dissemination to various user groups. INTAROS supports a number of systems providing data from the ocean in delayed mode as well as in near-real time mode, but only a few operate in the ice-covered areas.</p><p>Autonomous observing platforms used in the ice-free oceans such as Argo floats, gliders, and autonomous surface vehicles cannot yet be used operationally in ice-covered Arctic regions. The limitation is because the sea ice prevents these underwater platforms from reaching the surface for satellite communication and geopositioning. To improve the Arctic Ocean Observing capability OceanObs19 recommended ‘to pilot a sustained multipurpose acoustic network for positioning, tomography, passive acoustics, and communication in an integrated Arctic Observing System, with eventual transition to global coverage’. Acoustic networks have been used locally and regionally in the Arctic for underwater acoustic thermometry, geo-positioning for floats and gliders, and passive acoustic. The Coordinated Arctic Acoustic Thermometry Experiment (CAATEX) is a first step toward developing a basin-scale multipurpose acoustic network using modern instrumentation.</p><p>To provide secure data delivery, submarine cables are needed either as dedicated cabled observatories or as hybrid cable systems (sharing the cable infrastructure between science and commercial telecommunications), or both combined. Several large-scale cabled observatories existing coastal areas in world oceans, but none on the Arctic Ocean. At OceanObs19 it was recommended to transition (telecom+sensing) SMART subsea cable systems from present pilots to trans-ocean implementation, to address climate, ocean circulation, sea level, tsunami and earthquake early warning, ultimately with global coverage. Cabled observatories, either stand alone or branching from a hybrid system, could provide power and real time communication to support connected water column moorings and sea floor instrumentation as well as docking mobile platforms. Subsea cable developers are looking into the possibility to deploy a communication cable across the Arctic Ocean from Europe to Asia, because this offers a much shorter route compared to the terrestrial cables.</p><p> An international consortium of leading scientists in ocean observing with experience in state-of-the-art technologies on platforms, sensors, subsea cable technology, acoustic communication and data transmission plan to establish a project to implement and test the system based on experience from the CAATEX experiment and other Arctic observing system experiments. The INTAROS project is presently developing a Roadmap for an integrated Arctic Observing System, where multipurpose ocean observing systems will be one component.</p>

Measurement of the Core Human Body Temperature by Means of Passive Acoustic Thermometry

The purpose of the study. To determine whether it is possible to use passive acoustic thermometry to measure the core temperature of human body regions. Materials and methods. Thermal acoustic radiation was measured by a multichannel acoustic thermograph with a threshold sensitivity of 0.3°С at an integration time of 10 s. A portable computer infrared thermograph with a sensitivity of 0.1°С was used to measure the superficial temperature. Results. Measurements of thermal acoustic radiation of the right hypochondrium of the study subject were carried out to obtain an integral temperature of the liver after intake of sugar. At the same time, blood glucose concentrations were measured. The glucose level increased from 4 to 8 mmol/l within an hour and a half; then it began to decline. The acoustic radiation temperature increased by 2°С with a half an hour delay after the increase in the glucose level. Model calculation showed that the liver temperature increased from 37 to 38°С. Conclusion. It was shown that passive acoustic thermometry can be used to measure the core temperature of different regions of the human body. The proposed method may be useful in the emergency medicine.