Search

The multifunctional pulse equipment allowіng to use the method of amplitude-independent internal friction in the frequency range 7.5 to 232.5 MHz is described. Equipment gjves the possibility to investigate the peculiarities of the process of phonon-dislocation interaction in crystals, to carry out thermoactivation analysis of the process of dislocation of the dislocations about the stoppers under the action of temperature and elastic loading, to study processes of dislocation and mechanical relaxation in loaded samples in the quasi-elastic and plastic strain range.

Here, the feasibility of using nonimaging pulse-echo ultrasound as a method of noninvasively detecting a bolus in the proximal esophagus was demonstrated. To accomplish this, patient swallows were recorded on a clinical ultrasound device with research interface that allowed for collection of the pulse-echo data. These ultrasound data of the proximal esophagus were processed with a series of signal processing techniques in both the temporal and spectral domains, which revealed characteristic signatures that were unique for both liquid and food boluses compared to the normal collapsed esophageal state. Since substantial amounts of laryngopharyngeal reflux are gaseous in nature, future work will revolve around expanding the data set to include boluses of gaseous refluxate, a standardized methodology for capturing bolus events; developing automated detection tools for identifying laryngopharyngeal reflux for an extended duration; and assessing technology limitations due to user error.

Buildings, bridges, roads, and other structures need to be regularly maintained if they are to last. In general, if a defect is detected early, the cost of its remediation is typically much lower than if the structure is allowed to degrade for months or years. A key means of locating hidden defects are non-destructive testing methods. This paper describes measurements that compare three non-destructive methods applied to a concrete bridge and a laboratory specimen with artificial defects to simulate cavities. Three methods (infrared thermography, ground-penetrating radar and ultrasonic pulse echo) were used to measure the depth and size of cavities in the concrete panel. Furthermore, the measurements were made using two different brands of radar and two different thermal imaging cameras from the same manufacturer. Lastly, the NDT methods were compared across general performance criteria in terms of accuracy, testing practicality, and costs.

Ultrasonic is one of the well-known methods for surface roughness measurement, but small roughness will only lead to a subtle variation of transmission or reflection. To explore sensitive techniques for surfaces with small roughness, nonlinear ultrasonic measurement in through-transmission and pulse-echo modes was proposed and studied based on an effective unit-cell finite element (FE) model. Higher harmonic generation in solids was realized by applying the Murnaghan hyperelastic material model. This FE model was verified by comparing the absolute value of the nonlinearity parameter with the analytical solution. Then, random surfaces with different roughness values ranging from 0 μm to 200 μm were repeatedly generated and studied in the two modes. The through-transmission mode is very suitable to measure the surfaces with roughness as small as 3% of the wavelength. The pulse-echo mode is sensitive and effective to measure the surface roughness ranging from 0.78% to 5.47% of the wavelength. This study offers a potential nondestructive testing and monitoring method for the interfaces or inner surfaces of the in-service structures.

This work presents a method to estimate average anisotropy in speed of sound of soft tissue using pulse-echo ultrasound. In particular, our setup includes a passive acoustic reflector located opposite to the ultrasound probe, with tissue in between. This enables the generation of strong reflections from which we measure their traveltimes. We use ray-based approaches to derive the forward problem that relates observed traveltimes with speed of sound anisotropy parameters. The accuracy of the forward modelling is verified using numerical wave propagation simulations. We finally show the occurrence of anisotropy in muscle tissue using in-vivo data.

We report on a dual-fiber ultrasound probe for pulse-echo imaging. For ultrasound generation, a fiber is coated with a highly absorptive overlay made of carbon nanotube composite at its distal end. Ultrasound waves with a peak-to-peak amplitude of over 2.5 MPa can be photothermally generated by injecting nanosecond laser pulses. The scattered ultrasound waves at the specimen are detected by a paired fiber-laser-based ultrasound sensor, by translating the pressure waves into the variation of lasing frequencies. The probe has a diameter of 2.5 mm and an ultrasound spectrum centered at 22 MHz, and 90% -6 dB bandwidth. Ex vivo ultrasound imaging of a biological tissue has been performed with axial and lateral resolutions at 150 and 62 μm, respectively, by linearly scanning the probe, detecting the scattered waves and then forming an image via back projection. The all-fiber ultrasound probe offers an alternative approach towards next-generation intravascular and gastroenterological endoscopes.

After 100 years of theoretical treatment of speckle patterns from coherent illumination, there remain some open questions about the nature of ultrasound speckle from soft vascularized tissues. A recent hypothesis is that the fractal branching vasculature is responsible for the dominant echo pattern from organs such as the liver. In that case an analysis of cylindrical scattering structures arranged across a power law distribution of sizes is warranted. Using a simple model of echo strength and basic transformation rules from probability, we derive the first order statistics of speckle considering the amplitude, the intensity, and the natural log of amplitude. The results are given by long tailed distributions that have been studied in the statistics literature for other fields. Examples are given from simulations and animal studies, and the theoretical fit to these preliminary data support the overall framework as a plausible model for characterizing ultrasound speckle statistics., 26 pages, 8 figures

We consider the problem of nondestructive quality control of complex structured articles, in particular, hydroacoustic antennas. Those features in the structure of these products are determined that affect the choice of methods and means of such control. The possibility of using ultrasonic methods (in particular, the pulse echo method with immersion technique of acoustic contact) and means for monitoring the quality of hydroacoustic antennas have been investigated; means have been proposed to ensure the automation of control.

A Summary A pilot study on the use of P-EU to identify patients without osteoporosis and/or a subclinical vertebral fracture after a recently sustained non-vertebral fracture (NVF).Introduction Screening with portable devices at emergency departments or plaster rooms could be of interest to limit referrals for dual X-ray absorptiometry (DXA) and vertebral fracture assessment (VFA). We calculated the number of negative tests for osteoporosis and/or subclinical vertebral fractures (VFs) using pulse-echo ultrasonometry (P-UE) at different thresholds.Patients and methods In this cross-sectional study, 209 consecutive women of 50-70 years with a recent non-vertebral fracture (NVF) were studied at the Fracture Liaison Service (FLS) of one hospital. All women received DXA/VFA and P-EU (Bindex (R)) assessments. Various P-EU thresholds (based on the density index (DI, g/cm(2))) were analyzed to calculate the best balance between true negative (indeed no osteoporosis and/or subclinical VF) and false negative tests (osteoporosis and/or subclinical VF according to DXA/VFA).Results Eighty-three women had osteoporosis (40%) and 17 women at least one VF (8%). Applying the manufacturer's recommended P-EU threshold (DI 0.844 g/cm(2)) being their proposed cut-off for not having hip osteoporosis resulted in 77 negative tests (37%, 31% true negative and 6% false negative tests). A DI of 0.896 g/cm(2) resulted in 40 negative tests (19.3%) (38 true negative (18.3%) and 2 false negative tests (1.0%)).Conclusion The application of P-EU enables the identification of a substantial proportion of women with recent non-vertebral fractures at the FLS who would not need a DXA/VFA referral because they had no osteoporosis and/or subclinical vertebral fractures. The most conservative P-EU threshold resulted in 18.3% true negative tests verified by DXA/VFA against 1% false negative test results.

Background: Pulse-echo ultrasonography (PEUS) is a novel ultrasound method that measures the thickness of cortical bone at peripheral skeletal sites with a handheld device connected to a personal computer using proprietary software. Previous studies have shown a significant correlation between density index (DI), a PEUS-derived parameter, and bone mineral density (BMD) measured by dual-energy X-ray absorptiometry at the hip. DI thresholds that discriminate patients likely to have osteoporosis with 90% sensitivity and 90% specificity have been established in a population of Caucasian women in Finland and validated in a study of predominately Caucasian women in the state of Minnesota in the USA. The DI thresholds have not previously been evaluated in non-Caucasian populations. Methodology: This study aimed to determine whether previously established DI thresholds in Caucasian women require adjustment in Hispanic women. PEUS measurements at the proximal tibia and dual-energy X-ray absorptiometry BMD at the hip were evaluated in Caucasian and Hispanic women at a single investigative site in Albuquerque, New Mexico, USA. DI was calculated for each patient and compared with BMD. The performance of DI threshold values for these populations was compared. Results: The study enrolled 293 postmenopausal women (153 Caucasian, 140 Hispanic) with and without osteoporosis. The sensitivity and specificity for DI thresholds to distinguish women with total hip or femoral neck T-score ≤ -2.5 or > -2.5 was similar in Caucasians (sensitivity 80%, specificity 86%) and Hispanics (sensitivity 80%, specificity 91%). Conclusions: The findings of this study confirm the utility of previously established DI thresholds to identify women who are likely or unlikely to have osteoporosis and suggest that the same thresholds can be used for postmenopausal Caucasian and Hispanic women.

The results are presented from computer simulations of acoustic pulse propagation in heterogenous media mimicking the human head in two-dimensional and three-dimensional geometries. In the three-dimensional experiment, the cranial bone is presented as a liquid layer with a speed of sound corresponding to that of longitudinal waves in the bone. In the two-dimensional experiment, both longitudinal and transverse waves are considered. Based on data obtained in the numerical experiments, the possibility of obtaining ultrasound images of point scatterers by compensating for aberrations introduced by cranial bones is studied. It is shown that even a simple time delay correction along straight rays greatly improves the quality of an ultrasound image obtained through a nonuniform-thickness solid layer.

We aimed to quantitatively investigate the relationship between amplitude-based pulse-echo ultrasound parameters and early degeneration of the knee articular cartilage. Twenty samples from six human femoral condyles judged as grade 0 or 1 according to International Cartilage Repair Society grading were assessed using a 15-MHz pulsed-ultrasound 3-D scanning system ex vivo. Surface roughness (Rq), average collagen content (A1) and collagen orientation (A12) in the superficial zone of the cartilage were measured via laser microscopy and Fourier transform infrared imaging spectroscopy. Multiple regression analysis with a linear mixed-effects model (LMM) revealed that a time-domain reflection coefficient at the cartilage surface (Rc) had a significant coefficient of determination with Rq and A12 (RLMMm2=0.79); however, Rc did not correlate with A1. Concerning the collagen characteristic in the superficial zone, Rc was found to be a sensitive indicator reflecting collagen disorganization, not collagen content, for the early degeneration samples.

An ultrasonic synthetic aperture focusing technique (SAFT) using a root mean square (RMS) velocity model is proposed for pulse-echo immersion testing to improve the computational efficiency. Considering the immersion ultrasonic testing of a steel block as an example, three kinds of imaging were studied (B-Scan, SAFT imaging based on ray tracing technology and RMS velocity). The experimental results show that two kinds of SAFT imaging have almost the same imaging performance, while the efficiency of RMS velocity SAFT imaging is almost 25 times greater than the SAFT based on Snell’s law.

Pipeline faults like leakage and blockage always create problem for engineers. Detection of exact fault quantity and its location is necessary for smooth functioning of a plant or industry and safety of the environment. In this paper brief discussion is made on various pipeline fault detection methods viz. Vibration analysis, Pulse echo methodology, Acoustic techniques, Negative pressure wave based leak detection system, Support Vector Machine (SVM) based pipeline leakage detection, Interferometric fibre sensor based leak detection, Filter Diagonalization Method (FDM), etc. In this paper merit and demerits of all methods are discussed. It is found that these methods have been applied for specific fluids like oil, gas and water, for different layout patterns like straight and zigzag, for various lengths of pipeline like short and long and also depending on various operating conditions. Therefore, a comparison among all methods has been done based on their applicability. Among all fault detection methods, Acoustic reflectometry is found most suitable because of its proficiency to identify blockages and leakage in pipe as small as 1% of its diameter. Moreover this method is economical and applicable for straight, zigzag and long, short length pipes for low, medium and high density fluid.

We have introduced a correlating synthesis (CS) method for high-resolution terahertz (THz) imaging. The efficiency of the CS method was verified by imaging experiment of metal cylinders using a pulse reflection mode terahertz time-domain-spectrometry system. In this paper, we study the influence of layered dielectric in the propagation path of THz wave. A method of propagation time correction by ray tracing in the dielectric layer is proposed. The efficiency on decreasing the distortion and artifact images is verified by imaging experiment with a dielectric substrate board. Moreover, it is noticed that the appropriate correlation interval used in CS processing depends on the shape of the target. We propose a method of synthesizing the images derived from a series of different correlation intervals, which ensures the robustness of parameter independent with the target. The efficiency of the proposed method is verified by comparison imaging experiments using samples of different targets on a substrate board.

The correlation in bone microstructure for ultrasound pulse echo technique is still less accurate compared to through transmission technique. Previous works demonstrated, reflected two modes wave has significant association with bone porosity. The paper aims is to conduct simulation using pulse echo technique to examine the relationship between fast and slow waves with porosity of 2-dimensional cancellous bone models by comparing the result to through transmission technique. The “incident” and “reflected” waves were separated using bandlimited deconvolution method by estimating time threshold of fast and slow waves' transfer function. The parameters of the waves were computed, plotted versus porosity for six different thicknesses and the correlation coefficients between them were compared. The incident and reflected fast wave attenuations show marginally significant correlation with porosity for both bone models orientations. Wave propagation for parallel orientation dominated by incident and reflected fast wave, meanwhile, perpendicular orientation dominated by incident slow wave. The thickness factor affected wave amplitude but less affected the attenuation. Because of propagation loss, reflected wave shows lower correlation to porosity compared to incident wave. Hence, analyzing fast and slow waves might improve the measurement accuracy of pulse echo technique compared to using single mode wave to estimate bone quality.

Characterization of delamination fields in 3D for impact-damaged composites is necessary to achieve the USAF objective of damage tolerance for polymer matrix composites. Oblique angle pulse echo ultrasound inspection has been hypothesized as a potential technique to address this nondestructive characterization need, and modeling results presented last year support this hypothesis. Experimental results are presented showing that the received signals are much lower than predicted by the idealized model, and lower than could reasonably be detected without a priori knowledge of the delamination field. Reasons for this are presented and discussed.

This paper presents a study on blood flow velocity profile estimation based on the pulse-echo RF signals generated with adaptively varying pulse-shooting intervals (VPI). With the purpose of evaluating the correctness and reliability about the estimation of blood flow velocity profile, the relevant simulation experiments are carried out in this paper based on a Field II ultrasound emulation model for common carotid artery without stenosis lesions. In simulation experiments, the RF signals are firstly generated with the fixed pulse-shooting interval (FPI) of 1/10000 s and VPIs predefined by parabolic velocity profile of blood flow (VPI_PV). Then the relevant PW Doppler signals are obtained for estimating the blood flow velocity profiles by employing the autocorrelation algorithm. It can be found from the results that the estimated blood flow velocity profiles from the PW Doppler signals of VPI_PV have enhancing validity compared with that received from the PW Doppler signals of FPI. The blood flow velocity profiles with enhanced validity would be used as basic contents for disease diagnosis.

The risk of suffering from osteoporosis is increasing day by day, specially the people with increasing age are at high risk. Nowadays, different cure and preventives have been taken to minimize the risk and sufferings of osteoporosis along with lifestyle interference. Till now, the Dual energy X-ray Absorptiometry(DXA) is known as the ultimate “gold standard” because of having certified management qualification to prevent it. But, it comes with some particular restrictions like high cost, vast size of equipment and most significantly the use of ionizing radiation which makes it unsuitable for an elementary stage of healthcare. Other methodologies like QCT, Radiographs could not show proper skill in this site. This study describes a low cost, ionizing radiation free ultrasound method which is based on pulse-echo measurements using ultrasound simulation software wave2000 plus for the determination of bone thickness. Thickness has been calculated from three different model of bone sample using the time delays obtained from the transmitted and echo signals through the bone models. Presently, ultrasound methods are able to diagnose osteoporosis more effectively by characterizing between subjects with fractures. Therefore, this study will help to form a basis for the diagnosis of osteoporosis at an elementary stage.

This paper presents the fabrication and characterization of ultrasound brain phantom, which was characterized with 3.5 MHz transducer. Etylenglicol and bovine gelatin was used in the fabrication. The study focuses in the measurement of the speed of sound and attenuation coefficient in the tissue by using the pulse-echo and transmission methods in order to compare the results and evaluate the methods. The obtained results in this study are useful for the development of ultrasound brain phantom similar to that of the human brain.

Ultrasonic inspection provides a noninvasive means of probing the interior of a composite structure. The primary purpose is for the verification of integrity, quality, and reproducibility of the final product during manufacture; as a diagnostic tool for in-service evaluation during maintenance of a component; and as a final characterization in a retirement-for-cause setting.

Speed of sound (SoS) could prove useful as a biomarker for detecting and staging non-alcoholic fatty liver disease due to its dependence on fat concentration in the liver. However, current ultrasound SoS estimators yield poor accuracy and/or are difficult to implement on traditional pulse-echo scanner architectures. We propose a model and a method to estimate speed of sound in a localized region of tissue with high accuracy that can be implemented on commercial ultrasound systems.

Deep brain stimulation (DBS) is an effective treatment for a variety of brain disorders, including Parkinson's disease, depression and chronic pain. However, there is no reliable method to non-invasively image electric current flow generated by a DBS. In this study, we demonstrate 4D current source density imaging based on the acoustoelectric (AE) effect, which integrates an ultrasound beam with electrical recording, to map current flow produced by a clinical DBS device. AE imaging was able to accurately determine the polarity, magnitude and location of the current densities near the DBS device placed in physiologic saline with a signal-to-noise ratio of 17.1 dB using stimulation parameters similar to what are used on patients. Pulse echo (PE) ultrasound was acquired simultaneously to provide additional information regarding the spatial coordinates and structure of the DBS without need of additional techniques. These results suggest that AE imaging combined with PE ultrasound may provide valuable feedback during and after implantation of a DBS device.

This paper deals with finding of defects, such as cracks, breakdowns and inclusions in rails and in ship plates, by ultrasound technique. Pulse echo method and twin beams technique is some of the ultrasonic inspection methods we have used for thickness measurements and for inspection of the welds. Initially, the thickness of rails and ship plates was measured by ultrasound devices using straight beam transducers and then the weldings of these samples were checked by using angle beam transducers.

본 연구에서는 초음파 탐상시험의 펄스 반사법으로 각각 용접결함에 따른 초음파 펄스파형모형을 연구하였다. 균열은 예리하고 선명한 신호들을 발생한다. 탐촉자를 결함주위로 이동하면 에코높이는 변한다. 긴 균열에서는 탐촉자가 결함 주위를 원형으로 목돌림주사법을 사용하여 탐상하면 에코높이는 급격히 감소한다. 그 에코 봉우리는 바늘과 같이 얇고 날카롭다. 기공은 단일 결함으로부터 발생하는 에코는 예리하고 선명하다 하지만 집단의 기공들은 다수의 반사들이 중첩되고 트레이스가 들쭉날쭉한 에코가 발생한다. 슬래그 개재물은 크랙과 슬래그 결함위치에서 각각 목돌림 주사법을 사용하여 탐상하면 그 에코형상은 어느 정도 차이를 볼 수 있었다. crack은 그 에코높이가 급격히 변하는 반면에 슬래그 개재물은 증가 ${\rightarrow}$ 감소 ${\rightarrow}$ 증가 ${\rightarrow}$ 감소된다. 또한 다수 밀집된 기공의 위치에서 결함은 대표적 에코형상과 같은 잡다한 에코형상은 슬래그에서는 볼 수 없었다. 용입불량은 결함의 에코형상은 크랙과 같이 날카롭고 예리하게 나타났고, crack과 비슷한 에코형상은 갖고 있었다. 【This study examined the ultrasonic pulse reflection method(UPRM) for testing each ultrasonic pulse waveform model(UPWM) based on weld defects. The sharp crack of a clear signal was generated. The echo height of the defective probes changed according to the location. In a long crack in a circle around the defective probes, the Swivel scanning echo height when using the particle was reduced drastically. The peaks in the echo were thin because the needle was pointed. The porosity defects arising from a single echo was sharp and crisp, but a number of pores of the collective reflection overlapped and ajagged echo was observed. Slag, slag inclusions, cracks, and defects at the Swivel scan of each particle using the echo shape showed difference in the degree. Cracks were revealed as sudden changes in the echo height of the slag inclusions: increase ${\rightarrow}$ decrease ${\rightarrow}$ increase ${\rightarrow}$ decrease. In addition, the location of a number of defects in the dense pore geometry, such as a typical echo sundry, revealed the shape in the slag. Poor penetration of the defect echo, revealed the cracks to have a sharp-edged, crack-like shape with an echo.】

This paper deals with the study of A Scans obtaine d from sub assembly head top used in a Prototype Fast Breeder Reactor. A sub-assembly head top is the specimen used to deter mine the effect of bowing on A Scans. The condition of bowing has been simulated. The A Scans are obtained under normal co nditions of the ring and also under simulated bowi ng conditions. The envelope of the A Scans under both the conditions h ave been compared . It is found that the two edges of the ring are clearly indicated through the A Scan. Under normal conditio ns, the two edges have a slight difference in the d epth. This is due to the constructional feature of the object. But under sim ulated conditions, the two edges are obtained at tw o different depths, of magnitude higher than the normal conditions. The sin the A Scans is clearly seen It is observed that greater the tilt given for simulated bowing, larger is the shift in the depth of the two edges of the ring.

Distributed temperature sensing has important applications in the long term monitoring of critical enclosures such as containment vessels, flue gas stacks, furnaces, underground storage tanks and buildings for fire risk. This paper presents novel techniques for such measurements, using wire in a spiral configuration and having special embodiments such a notch for obtaining wave reflections from desired locations. Transduction is performed using commercially available Piezo-electric crystal that is bonded to one end of the waveguide. Lower order axisymmetric guided ultrasonic modes were employed. Time of fight (TOF) differences between predefined reflectors located on the waveguides are used to infer temperature profile in a chamber with different temperatures. The L(0,1) wave mode (pulse echo approach) was generated/received in a spiral waveguide at different temperatures for this work. The ultrasonic measurements were compared with commercially available thermocouples.

Recent advances in optical transmission and reception of ultrasound have enabled pulse-echo imaging using fiber-optic probes that are suitable for guiding clinical intracardiac and intravascular procedures. In vivo images from pre-clinical models will be presented.

In 2D 360° Spatial Compounding (SC) envelope detected pulse-echo data from a conventional linear probe is superimposed from 360° in parallel cross-sectional planes to improve B mode image quality. Latest research of our group has shown that extending this concept to 3D by utilizing a motorized 1D array (3D probe) brings along substantial gain in image quality and significance of 360°-SC for diagnosis. However, so far only initial in-vivo results, limited in image quality due to system performance, have been shown for a female breast. In this contribution we will present examples of latest 3D-360°-SC in-vivo results for a female breast and also for a finger joint demonstrating the promising potential of this modality for breast cancer and rheumatoid arthritis diagnosis.

The objective of this study is to explore the feasibility of using ultrasound to detect mastoid effusion (ME). In the past, ultrasound has been used to measure middle ear effusion (MEE) by injecting water into the external ear canal to measure echoes from the tympanic membrane, which is uncomfortable for the patient. It has been shown that air cells in the mastoid of patients with MEE are filled with fluid, which implies that ME could be a useful indicator of MEE. This study suggests using ultrasound to detect ME as a potentially noninvasive approach for MEE detection. In vitro experiments were performed on ten cadaver samples of the human ear. A single-element 1 MHz transducer was used to measure the mastoid of each cadaver before and after injecting water into the mastoid. The experimental results showed that the relative amplitudes of ultrasonic signals differed significantly between before (0.24 ± 0.09, mean ± standard deviation) and after (0.15 ± 0.03) the water injection (p0.05, t-test), demonstrating that the ultrasonic reflection can be used to detect ME. The location of the human mastoid under the skin behind the ear allows external measurements, and hence ultrasound-based ME detection may be an alternative, noninvasive diagnostic approach to detecting MEE in the future, providing an examination that avoids discomfort.

Ultrasonic is one of the most common uses of non-destructive evaluation technique. It could detect flaws inside the structure and on the surface such as voids, holes and cracks. In this investigation, a 304 steel block with a small hole inside the structure was fabricated. The radius of the hole was evaluated by the pulse-echo ultrasonic technique. In this work, 2.25MHz, 5MHz and 10MHz of incident waves were employed to detect the radius of the hole inside the structure. The errors of a hole with 2.5 mm radius measured by 5 MHz and 10MHz longitudinal wave were 1.15% and 6.6%, respectively. Experimental results showed that the accuracy of flaw sizing detection by ultrasonic technique depends on the frequency of the incident wave.

apan Abstract. This paper aims at a quantitative nondestructive evaluation of pipe wall thinning using an electromagnetic acoustic transducer. Type 304 stainless steels sample specimens that are fabricated by a semi ellipse were provided for our experiments. First, results of measurement and simulation experiments are shown using the provided test samples. The variety of simulation results showed good agreement with laboratory experimental results. Second, the sensitivity of pulse echo signals wit h respect to corrosion geometry of pipe wall is investigated. Finally, the feasibility studies of our sizing methodology are summarized for evaluating FAC and early LDI test samples.

The information of acceleration of a highly maneuverable target can be helpful to enhancing the performance of the tracker and facilitating the classification of targets. However, the current radars cannot provide information on the acceleration of the target in signal processing. Conventionally, acceleration is estimated by using Kalman filtering in several pulse echoes. There are limitations and shortcomings in this method because of its low precision. This paper proposes a Hough-ambiguity transformation (HAT) method for estimating the acceleration within one pulse. Simulations results validate the effectiveness of the proposed algorithm under several conditions with different pulse durations, signal to noise ratios (SNR), searching steps and searching radii respectively. Simulation results also show that the performance of the proposed method is superior to that of other methods.

Corrosion of reinforcing steel in concrete is one of the major durability problems faced by civil engineers as they maintain an aging infrastructure. The problem accelerates since steel is embedded inside concrete. If it remains unnoticed inside concrete, it further accelerates and can cause loss of life and property. This article discusses a nonintrusive corrosion monitoring technique for early detection of damages in steel embedded in concrete. Corrosion manifests itself in debond and pitting steel bars. Guided ultrasonic waves offer a potentially attractive solution for this problem. But it is imperative to excite the right mode for detection of a particular type of corrosion. In the present work, longitudinal guided ultrasonic waves have been utilized to monitor notch and debond defects in steel bars in concrete simulating pitting and delamination phenomena caused by corrosion. Two ultrasonic techniques of pulse transmission and pulse echo were used to monitor the healthy and damaged specimens. The developed methodology is successfully applied for real time monitoring of RC beam specimens undergoing accelerated chloride corrosion. The ultrasonic signals effectively relate to the state of reinforcing bars.

Cooling elements in operating furnaces, such as waffle coolers, finger coolers, cooling staves, and plate coolers, are subject to wearing and deterioration over time. Ultrasonic (UT) pulse echo is an efficient nondestructive testing methodology to monitor the thickness and quality of the cooling blocks through periodical inspections; however, the highly dampening properties of copper and the high temperatures on the hot face of the cooling elements could cause errors in UT thickness measurements. To eliminate potential errors in UT measurements, a study was conducted to determine the correct temperature and velocity distributions and relationship in waffle coolers. In this study, a combination of mathematical modeling and experimental work was used to establish a relationship between the temperature and the speed of ultrasonic waves in copper elements.

During hunting, insectivorous bats such as Eptesicus fuscus progressively vary the repetition rate, duration, frequency and amplitude of emitted pulses such that analysis of an echo parameter by bats would be inevitably affected by other co-varying echo parameters. The present study is to determine the variation of echo frequency selectivity of duration-tuned inferior collicular neurons during different phases of hunting using pulse-echo (P-E) pairs as stimuli. All collicular neurons discharge maximally to a tone at a particular frequency which is defined as the best frequency (BF). Most collicular neurons also discharge maximally to a BF pulse at a particular duration which is defined as the best duration (BD). A family of echo iso-level frequency tuning curves (iso-level FTC) of these duration-tuned collicular neurons is measured with the number of impulses in response to the echo pulse at selected frequencies when the P-E pairs are presented at varied P-E duration and gap. Our data show that these duration-tuned collicular neurons have narrower echo iso-level FTC when measured with BD than with non-BD echo pulses. Also, IC neurons with low BF and short BD have narrower echo iso-level FTC than IC neurons with high BF and long BD have. The bandwidth of echo iso-level FTC significantly decreases with shortening of P-E duration and P-E gap. These data suggest that duration-tuned collicular neurons not only can facilitate bat's echo recognition but also can enhance echo frequency selectivity for prey feature analysis throughout a target approaching sequence during hunting. These data also support previous behavior studies showing that bats prepare their auditory system to analyze expected returning echoes within a time window to extract target features after pulse emission.

In this article a method to evaluate defect dimensions in adhesively bonded lap joints based on the measurement of scattering effects of ultrasonic guided waves is presented. A simplified theoretical model is proposed which was initially tested in plates with through holes. The experimental results obtained using both pitch-and-catch and pulse-echo techniques for 500 kHz and 1 MHz frequencies confirm the validity of this model. To evaluate the lap joint defects, a set of samples with artificial defects were manufactured and the form and dimensions were confirmed using C-scan ultrasonic images. With the same methodology used in through-hole analysis, scattering effects of defects were measured. The results obtained with the pitch-and-catch technique with 1 MHz transducers allow us to say that an estimate of defect dimensions could be done by using the proposed model with reasonable accuracy and according with the predictions.

Part 1 presents the signal generation of an ideal pwDoppler system in the time and frequency domain using the means of the one-dimensional system theory. Problems of realisation are ignored, but tissue properties like absorption and scattering are taken into consideration. A comparison is made with pulse echo signals from tissue.

Angiodynography is a newly developed system that enables Doppler sonography to be used to obtain a colour-coded real-time image of the blood vessels in the familiar ultrasound slice image. A new computerised technique allows both the familiar pulse echo signal and the Doppler shift of the signal resulting from movement in the body to be displayed for each point on the ultrasound slice plane. Stationary tissue structures are shown as the familiar grey scale image, while movement such as of the blood is shown in colour. 453 patients were examined. Normal and pathological flow measurements were obtained in the carotid artery, the jugular vein, in renal transplants, in the thyroid, the testis and in the urethra. Pathological flow velocities were visualised in stenosis, tumours and diffuse alterations of parenchyma.

Measurements of the acoustic nonlinearity parameter β are frequently made for early detection of damage in various materials. The practical implementation of the measurement technique has been limited to the through-transmission setup for determining the nonlinearity parameter of the second harmonic wave. In this work, a feasibility study is performed to assess the possibility of using pulse-echo methods in determining the nonlinearity parameter β of solids with a stress-free boundary. The multi-Gaussian beam model is developed based on the quasilinear theory of the KZK equation. Simulation results and discussion are presented for the reflected beam fields of the fundamental and second harmonic waves, the uncorrected β behavior and the properties of total correction that incorporate reflection, attenuation and diffraction effects.