Attenuation Of Ultrasonic Energy Research Articles

Dual mode imaging guided multi-functional bio-targeted oxygen production probes for tumor therapy

Focused ultrasound ablation surgery (FUAS) is a novel therapy with a wide range of potential applications. However, synergists are crucial to the therapy process due to the ultrasonic energy's attenuation properties. As a result of the complex hypoxic environment in the tumor area and many factors, the existing synergists have limitations such as weak targeting, single imaging mode, and easy tumor recurrence after treatment. Because of the above deficiencies, this study intends to construct bio-targeted oxygen production probes consisting of Bifidobacterium that naturally target the hypoxia region of the tumor and multi-functional oxygen-producing nanoparticles equipped with IR780, perfluorohexane (PFH), CBP (carboplatin), and oxygen. The probes are expected to achieve targeted and synergistic FUAS therapy and dual-mode imaging to mediate tumor diagnosis and treatment. The oxygen and drugs carried in it are accurately released after FUAS stimulation, which is expected to alleviate tumor hypoxia, avoid tumor drug resistance, improve the effect of chemotherapy, and realize FUAS combined with chemotherapy antitumor therapy. This strategy is expected to make up for the deficiencies of existing synergists, improve the effectiveness and safety of treatment, and provide the foundation for future tumor therapy progress.Graphical

Research on ultrasonic phased array detection algorithm for TA15/Ti2AlNb multi-layer gradient material structure

Conventional ultrasonic detection methods can detect a TA15/Ti2AlNb gradient material multi-layer structure with many layers; the reflection and refraction phenomena of ultrasonic waves at the partition interface result in considerable attenuation of ultrasonic energy. It is difficult to achieve accurate focusing control of multi-array element synthetic beams, and internal defects cannot be detected. We explored the ‘ultrasonic velocity scale coefficient K’ algorithm to determine the ultrasonic beam propagation refraction path of a multi-layer gradient material structure. The algorithm makes full use of the refraction characteristics of ultrasonic waves on each material layer interface, establishes the acoustic ray-tracing model, analyzes the acoustic ray-tracing propagation path of each array element, and quickly obtains the focusing law. A TA15/Ti2AlNb gradient material specimen was prepared using laser melting deposition (LMD) technology, and a multi-layer structure model was established based on the finite difference time domain (FDTD) method to verify the focusing law. The experimental results of the ultrasonic phased array showed that the proposed algorithm effectively improved the defect detection signal-to-noise ratio (SNR) and imaging quality of the TA15/Ti2AlNb gradient material.

Ultrasonic energy attenuation characteristics in plastic deformation of 2219-O aluminum alloy

Ultrasonic energy attenuation characteristics in plastic deformation of 2219-O aluminum alloy

The Investigation of Ultrasonic Energy Attenuation in Aqueous Solutions

Large-scale application of ultrasonic cavitation in chemical engineering is hindered by the energy attenuation along the propagation direction. This paper is devoted to investigating the longitudin...

The Effect of Ultrasonic Energy on Joint Characterization in Ultrasonic Spot Welding Multilayer Tabs Used in Lithium-ion Battery Manufacturing

Lithium-ion battery for electric vehicles contains a large number of battery tabs with multiple and thin sheets. Dissimilar metals are often used for different electrodes, for example, the copper and nickel are often used for negative electrode and the aluminum is often used for positive electrode. Meanwhile the thickness of metal sheets are various at different locations. Ultrasonic spot welding is very capable of welding similar and dissimilar combinations. However, there are less heat generation and plastic deformation in the bottom interfaces where ultrasonic energy is difficult to reach. This will result in the unbonded region occurrence caused by ultrasonic energy attenuation. In this work, experimental investigation was conducted to identify the effect of ultrasonic energy on joint characterization in ultrasonic welding multiple tabs by comparing the plastic deformation in different layers and various joint interfaces. Two sonotrodes with different knurl size were used to produce the welding energy for the tabs joining. Samples were cross-sectioned along vibration direction to obtain hardness profiles and metallographic maps. The hardness profile can be used to identify the changes of grain morphology. Hardness and grain size changes in different layers were also studied to reflect how ultrasonic energy decrease from top to bottom in battery tabs. Thereby, the relationship between material attributes and ultrasonic energy loss was established based on the experimental results.

Prediction of grain orientation in dissimilar metal weld using ultrasonic response of numerical simulation from deliberated scatterers

Ultrasonic nondestructive testing plays an important role in structural integrity monitoring of dissimilar metal weld (DMW) structures in pressure vessels and piping of nuclear power plants. Inspection of DMW components is too complicated due to its anisotropic behavior to ultrasonic beam propagation. Many researchers are working rigorously to model the grain orientation and ultrasonic beam skewing in DMW structures but still not completely resolved yet. This paper is intended to estimate the grain orientation with the help of numerical simulation for a given asymmetric DMW component with specified scatterers. The DMW is fabricated from austenite stainless steel and carbon steel base metals with austenite stainless steel filler metal using Gas Tungsten-Arc Welding. To study this research a finite element method (FEM) based numerical simulation has been used to exactly evaluate the grain structure. This model mainly depends on the elasticity matrix which is a function of the grain orientation and attenuation of ultrasonic energy of the weld. Iterative measurement of grain orientation using macrograph of the etched weldment with 5 × 5mm mesh size was carried out then the attenuated elasticity matrix was fed into the FEM COMSOL software model as input parameter. Result obtained from numerical simulation (time of flight and amplitude) are validated with the experimental result and good agreement (above 0.8 correlation coefficient) have been observed at higher iterations. This macro-graphic information based numerical model shows the potential to predict the grain orientation of DMW.

A modified model for simulating the effect of temperature on ultrasonic attenuation in 7050 aluminum alloy

Knowing propagating properties of an ultrasonic wave can enhance the non-destructive testing techniques in alloy materials field, such as the electromagnetic acoustic transducer techniques, and the piezoelectric ultrasonic transducer techniques. When temperature is taken into consideration, the ultrasonic propagating attenuation become very complex process. In this paper, a loss factor coefficient function with change in temperatures is established and the loss factor damping model with temperature term is coupled into the equations of elastic wave motion. A modified frequency domain model for calculating the ultrasonic attenuation due to temperature changes in 7050 Aluminum alloy is then developed. The model is validated experimentally using a high power pulse transmitter/receiver RPR-4000, a resistant high temperature electromagnetic acoustic transducer set-up and a 7050 Aluminum alloy sample. The simulation and the experimental results are determined to be in good agreement. The numerical model is used to calculate the ultrasonic-waves field, the ultrasonic attenuation, and the ultrasonic propagation directivity considering the temperature effect. The modeling results indicate that the ultrasonic energy attenuation is significantly affected by temperature. When the temperature increases from 20°C up to 480°C, the ultrasonic energy attenuates by 32.31%. It is also found that the length of near acoustic field increases with the increase in temperature. There is a common basic mode for the attenuation of ultrasonic waves, in which the attenuated mode cannot be affected by other factors. Increasing the temperature or the frequency, the ultrasonic propagation can obtain an excellent directivity. Results obtained from the present model will provide a comprehensive understanding of design parameter effects and consequently improve the design/performance in the non-destructive testing techniques.

The Investigation of Ultrasonic Energy Attenuation in AISI 316 Stainless Steel Weld Joint

This research aims to study and describe the effect of microstructure on shape of distance amplitude correction (DAC) curve and ultrasonic inspectability of stainless steel weld joint. Two calibration blocks (side drilled hole block) were prepared from AISI 316 stainless steel plate according with ASME section V version 2013. One calibration block was varied the grain size by annealing process. The annealing temperature and holding time were 1,200 °C and 4 hours, respectively and then cooled down in furnace. AISI 316 Butt joint welding specimens were prepared to establish the artificial discontinuities. Lack of fusion and drill hole, diameter 1 and 2.5 mm, were selected to establish as discontinuities. Specimens were welded by gas tungsten arc welding and shielded metal arc welding process. Then, the gain size and microstructure of two calibration blocks were analyzed by microscope. The macrostructure, gain size and microstructure of weld joint were determined by microscope. Longitudinal and transverse wave with probe frequency 2.25 and 4 MHz and angle probe 45, 60 and 70 degrees were used to describe the effect of microstructure on shape of DAC curve and investigate the ultrasonic inspectability in stainless steel weld. The experiment results found that the ultrasonic energy of longitudinal and transverse wave in calibration blocks decreased as the gain size increased. The attenuation due to gain size affected to the shape of DAC curve. The grain size in heat effected zone (HAZ) of weld specimen is larger than base material and the ultrasonic transverse wave can detect lack of fusion and drill hole diameter 2.5 mm but cannot detect drill hole diameter 1 mm. The usefulness of this research is utilizable for searching the discontinuities in the weld zone of stainless steel by ultrasonic. The attenuation of ultrasonic energy in the weld zone of AISI 316 is usually high and the amplitude displayed at the screen is very low. This reason can be made the operator wrong result interpretation, if they did not consider about the attenuation from microstructure.

Energy transfer model and its applications of ultrasonic gas flow-meter under static and dynamic flow rates.

Most of the ultrasonic gas flow-meters measure the gas flow rate by calculating the ultrasonic transmission time difference between the downstream and upstream. Ultrasonic energy attenuation occurs in the processes of the ultrasonic generation, conversion, transmission, and reception. Additionally, at the same time, the gas flow will also affect the ultrasonic propagation during the measurement, which results in the ultrasonic energy attenuation and the offset of ultrasonic propagation path. Thus, the ultrasonic energy received by the transducer is weaker. When the gas flow rate increases, this effect becomes more apparent. It leads to the measurement accuracy reduced, and the measurement range narrowed. An energy transfer model, where the ultrasonic gas flow-meter under without/with the gas flow, is established by adopting the statistical analysis and curve fitting based on a large amount of experimental data. The static sub model without the gas flow expresses the energy conversion efficiency of ultrasonic gas transducers, and the dynamic sub model with the gas flow reflects the energy attenuation pattern following the flow rate variations. The mathematical model can be used to determine the minimum energy of the excitation signal for meeting the requirement of specific measurement range, and predict the maximum measurable flow rate in the case of fixed energy of excitation signal. Based on the above studies, a method to enhance the excitation signal energy is proposed under the output power of the transmitting circuit being a finite value so as to extend the measurement rage of ultrasonic gas flow-meter.

Ultrasound Elasticity Imaging System with Chirp-Coded Excitation for Assessing Biomechanical Properties of Elasticity Phantom.

The biomechanical properties of soft tissues vary with pathological phenomenon. Ultrasound elasticity imaging is a noninvasive method used to analyze the local biomechanical properties of soft tissues in clinical diagnosis. However, the echo signal-to-noise ratio (eSNR) is diminished because of the attenuation of ultrasonic energy by soft tissues. Therefore, to improve the quality of elastography, the eSNR and depth of ultrasound penetration must be increased using chirp-coded excitation. Moreover, the low axial resolution of ultrasound images generated by a chirp-coded pulse must be increased using an appropriate compression filter. The main aim of this study is to develop an ultrasound elasticity imaging system with chirp-coded excitation using a Tukey window for assessing the biomechanical properties of soft tissues. In this study, we propose an ultrasound elasticity imaging system equipped with a 7.5-MHz single-element transducer and polymethylpentene compression plate to measure strains in soft tissues. Soft tissue strains were analyzed using cross correlation (CC) and absolution difference (AD) algorithms. The optimal parameters of CC and AD algorithms used for the ultrasound elasticity imaging system with chirp-coded excitation were determined by measuring the elastographic signal-to-noise ratio (SNRe) of a homogeneous phantom. Moreover, chirp-coded excitation and short pulse excitation were used to measure the elasticity properties of the phantom. The elastographic qualities of the tissue-mimicking phantom were assessed in terms of Young’s modulus and elastographic contrast-to-noise ratio (CNRe). The results show that the developed ultrasound elasticity imaging system with chirp-coded excitation modulated by a Tukey window can acquire accurate, high-quality elastography images.

Research and Design for High Precision Ultrasonic Distance Measurement System

In this article, discussed the traditional method of ultrasonic distance measurement , analyzed the main factors that restrict to impove the precision, and according to the energy attenuation of ultrasonic transmission, designed a measurement method based on rebuilding the digital signal waveform, this method solved the measurement precision problem caused by the traditional threshold method, the accuracy is no longer affected by the attenuation of ultrasonic energy, achieved the consistency precision in full range, makes the measuring accuracy is nearly one hundred times higher than the threshold method.

Diagnostic medical ultrasound systems having a method and circuitry for front-end gain control

A system and method of processing received signals in an ultrasound imaging system is disclosed. In the system, the received signals are amplified by means of a gain controlled amplifier, and the gain of the amplifier is varied, by varying the load capacitance, as a function of depth (time) to compensate for the attenuation of ultrasonic energy at different depths within a patient's body.

Physical modeling of plaster and fiber/plaster composites setting from ultrasonic measurements

Experimental measurements of ultrasonic wave velocity and ultrasonic power attenuation are collected in plaster and composite short natural fibers/plaster matrix. During setting of these conglomerates, materials are mixed with different water/plaster ratios. A physical model of setting is proposed for these materials, to obtain time evolution of the solid skeleton during setting based on ultrasonic velocity and ultrasonic energy attenuation.

Ultrasonic nondestructive evaluation of matrix structures and nodularity in cast irons

The primary purpose of this research was to investigate the nondestructive ultrasonic wave response, in terms of acoustic velocities and attenuation of sound energy, in cast irons with different nodularities and matrix structures and its correlation with mechanical properties. The results indicated that the influences of matrix structures on the acoustic velocities were not apparent in the cast irons investigated. As to the nodularity, when graphites were largely spheroidal in shape (i. e., nodularity over 80 pct), the velocity of longitudinal waves propagation was about 5300 to 5500 m/s. The velocities seemed to decrease linearly down to nodularity of 25 pct, where velocity was approximately 4800 m/s. Below 25 pct nodularity, the values of acoustic velocity dropped rapidly to about 4000 to 4200 m/s. This represented the velocity of longitudinal waves propagation in gray cast iron, in which the graphites appeared in flake form. The analysis of the attenuation of ultrasonic amplitude indicated that when the nodularity of cast irons is low, the echo sound amplitude will decay more rapidly with respect to distance of echo sound travel. As to the matrix structures, ferritic, bainitic, ferritic-pearlitic (low pearlite content) and tempered martensitic matrix structures were found to have similar ultrasonic attenuation characteristics at the testing frequency of 2 MHz. A higher amount of pearlite (over 90 pct) or fresh martensite in the matrix of cast irons has resulted in faster attenuation of ultrasonic energy, with the fresh martensitic matrix being the fastest. At a testing frequency of 4 MHz, the attenuation of the ultrasonic amplitude in pearlitic and fresh martensitic matrices was found to be even greater than that of 2 MHz. However, other matrices exhibited similar attenuation behavior at both 2 and 4 MHz frequencies. The relationship between the mechanical properties of various cast irons and ultrasonic characteristics was also examined.

Quantitative Volume Backscatter Imaging

A conventional ultrasonic B-scan image is converted into a volume backscatter image by accounting for four propagation effects: dispersion of transmitted energy, beam width and beam intensity variations, inhomogeneous attenuation of ultrasonic energy, and signals resulting from specular reflections at interfaces. These images are a two-dimensional map of backscatter efficiency, are independent of details of the measurement system, and are quantitative images of an intrinsic property of tissue and other materials.

Measurement of the acoustic properties of a nerve-muscle preparation as a function of physiologic state

Nerve-muscle preparations of Sprague Dawley rats were exposed to low dosage ultrasound. The objectives were to measure the velocity of propagation and attenuation of ultrasonic energy in both the relaxed and contracted states. A tension-measuring system and associated ultrasonic instrumentation were designed to measure the tension developed in stimulated muscle and its corresponding acoustic parameters, ie the attenuation coefficient, α (db cm -1) and the velocity of propagation, c (ms -1). Each test was performed at ultrasonic frequencies 3.1, 5.35, and 7.68 MHz and with the preparation maintained at 23 ± 0.5° C. Attenuation of ultrasonic energy was observed to increase by 10 ± 0.5% in the active state from its value in the relaxed state. The relation between the attenuation and the acoustic frequency was found to be approximately linear over the frequency range tested. The velocity of propagation in the active state did not change appreciably from its value in the relaxed state and was observed to be independent of the acoustic frequency in the range used.

Spectrum and Contour Analysis of Ultrasonic Pulses for the Determination of Microstructure in Metals

The attenuation of ultrasonic energy in metals depends on the ratio of the ultrasonic wavelength to the grain diameter. Hence, microstructure can be determined by measuring the relative rate of energy loss in a specimen at various ultrasonic frequencies. Unfortunately, such measurements are extremely time consuming. A theoretical and experimental investigation carried out at Watertown Arsenal Laboratories indicates, however, that the desired relationship between ultrasonic attenuation and frequency can be obtained in a very quick manner if the test is carried out with ultrasonic pulses of rectangular envelope. Such pulses contain ultrasonic energy distributed over a fairly wide spectrum, and the influence of a frequency dependent energy loss can he determined either by spectrum or contour analysis of the attenuated ultrasonic signal.

Ultrasonic Velocity and Absorption in Liquid Helium

Measurements are given on the velocity and attenuation of ultrasonic energy in liquid helium at a frequency of 15 megacycles per second as a function of temperature from 1.57\ifmmode^\circ\else\textdegree\fi{}K to 4.5\ifmmode^\circ\else\textdegree\fi{}K. The velocity at 15 Mc/sec. was found to agree with results obtained at 1.3 Mc/sec. by previous investigators, and hence there is no dispersion in this frequency range. The attenuation measurements exhibit three important features: (a) in the upper temperature range of He I the measurements agree very well with classical theory, (b) at the $\ensuremath{\lambda}$-point the attenuation coefficient rises abruptly, presumably to infinity, indicating complete absorption of the ultrasonic energy, (c) just below the $\ensuremath{\lambda}$-point the attenuation (first sound in He II) has its smallest value and with lowering temperature the attenuation increases.