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Post-tensioning systems provide safe and efficient construction solutions for long span bridges. Despite the improved grouting practices over the past decade, existing post-tensioning systems may have significant amount of grout defects, which could lead to corrosion of the strands. Condition assessment of post-tensioning systems is necessary to allow bridge owners to take timely, proactive actions to mitigate or prevent further deterioration and unanticipated tendon failures. A detailed experimental study conducted to assess the performance of nondestructive evaluation techniques in detecting grout defects within internal tendons is presented herein. Nondestructive evaluation techniques that include Ground Penetrating Radar, Impact Echo, Ultrasonic Tomography, and Ultrasonic Echo are evaluated in terms of detecting the location and severity of fabricated grout defects in a full-scale post-tensioned U-girder mock-up specimen. While Ground Penetrating Radar can identify the location and profile of the internal tendons, particularly metal ducts due to strong reflections, this method did not provide any information about the defect conditions within the tendon. Both Impact Echo and Ultrasonic Echo techniques are effective in identifying the location of grout defects, but could not differentiate between water, void, or compromised grout conditions. The study clearly demonstrates the need for NDE techniques that are applicable to anchorage regions, and that are capable of estimating the severity and nature of grout defects in internal tendons.

There is a growing need for nondestructively evaluate the integrity of trees and wooden structural elements. Such an investigation can be performed with the use of different test methods. Nevertheless, in order to yield acceptable results, the test methods should consider the anisotropic nature of the wood, which includes the shape of the annual rings, and also the pith location in the cross-section. This paper presents a new method to determine the pith location of a tree or structural element made of timber or lumber based on ultrasonic tomography readings.

In this paper we evaluated a single plane ultrasonic tomography sensor and performed some experimentation to reconstruct three-dimensional profiles in a chemical bubble column. An array of 32 ultrasonic sensors was constructed and clamped on the exterior circumference of the column. The information of the profiles was captured based on time-of-flight and arrival-time analysis. Several phantom profiles were created and sampled using ultrasonic tomography techniques and the results were compared with high-speed camera images. The findings showed promising results where the reconstructed three-dimensional profiles matches with the high-speed camera images.

This paper concerns inspection of reinforced concrete elements, with particular emphasis on assessing the quality of the adhesive connection between steel and concrete. A novel theoretical model was developed to determine the paths of transmitted, refracted and reflected elastic waves as well as a creeping wave propagated along the inclusion surface. Imaging the internal structure of tested beams was based on wave propagation measurements carried out on their surface and computed tomography. The ray tracing was performed by the hybrid approach as a combination of the network theory and the ray bending methods. The obtained results indicated a great potential of ultrasonic tomography in detection of debonding in reinforced concrete structures.

With the increasing use of preplaced aggregate concrete in construction, the grout filling in preplaced aggregate concrete is important for ensuring proper consolidation and high mechanical performance. This paper proposes a framework for determining the injectable grout fluidity for preplaced aggregate concrete according to the rheological properties of the grout mixture, which are associated with the filling performance for the given aggregates. To assess the grout filling, cost-effective, nondestructive ultrasonic pulse velocity (UPV) testing was performed, and ultrasonic tomography images were constructed for visually identifying internal air voids, which were verified by high-resolution micro-computed tomography. Rheometer tests evaluated the rheological properties of the grout mixtures. The UPV-based void-detection results and grout rheological properties were employed to determine the injectable grout fluidity range.

Oil-water biphasic medium widely existed in mining and transportation process of petroleum industry, where visualized measurement processes vital importance in production increase, state monitoring and fault prognosis. Ultrasonic Tomography (UT) is a non-invasive and non-radioactive sensing modality in industrial Process Tomography, which is demonstrated as a competitive monitoring technique with great potential. However, facing the refraction effect of Ultrasound wave at oil-water interfaces, the accuracy of reconstruction algorithm is with large error and serious artifacts. To address the issue, a modified ray-tracing image reconstruction algorithm is proposed. The amplitude attenuation during ultrasound propagation in nonhomogeneous medium is quantitatively modeled to form absolute UT model. With ray tracing strategy applied and improved, the nonlinear refraction effect is characterized in the form of iterative update of sensitivity matrix, followed by which the sound speed mapping transfers reconstructed attenuation images to sound speed distribution for ray tracing computation. Numerical tests indicate that the proposed method significantly improves reconstruction accuracy through projection-based, regularization-based and algebraic-based inverse algorithms, which demonstrate its benefits in conducting oil-water biphasic medium imaging.

The work contains a description of studies of composite steel-concrete truss element under cyclic and static load which maximal value was increased from stage to stage up to a moment when the system lost its load capacity. During the loading process, truss deflections and slips between a concrete slab and steel top chord of the truss were measured. Also two methods of non-destructive testing were used between the particular loading cycles for an evaluation of stiffness decrease of truss elements resulting from increasing material defects, i.e. an analysis of free vibrations of the system and ultrasonic tomography tests were conducted. A common analysis of all experimental results aided additionally by FEM calculations enabled a complex evaluation of efficiency of using two aforementioned non-destructive methods in diagnostics of composite steel-concrete truss elements.

Ultrasound Computer Tomography (USCT) is a promising breast imaging modality under development. Comparison to a standard method like mammography is essential for further development. Due to significant differences in image dimensionality and compression state of the breast, correlating USCT images and X-ray mammograms is challenging. In this paper we present a 2D/3D registration method to improve the spatial correspondence and allow direct comparison of the images. It is based on biomechanical modeling of the breast and simulation of the mammographic compression. We investigate the effect of including patient-specific material parameters estimated automatically from USCT images. The method was systematically evaluated using numerical phantoms and in-vivo data. The average registration accuracy using the automated registration was 11.9mm. Based on the registered images a method for analysis of the diagnostic value of the USCT images was developed and initially applied to analyze sound speed and attenuation images based on X-ray mammograms as ground truth. Combining sound speed and attenuation allows differentiating lesions from surrounding tissue. Overlaying this information on mammograms, combines quantitative and morphological information for multimodal diagnosis.

Spent nuclear fuel (SNF) is one of the most hazardous types of nuclear power plant waste. This fact emphasizes the importance of careful handling and storage of SNF. There are two current state-of-the art technologies of SNF storage facility: wet and dry. It is important to mention that IAEA does not determine which kind of handling strategy should be chosen, however it is noted that dry storage of SNF could be used for one hundred years. Mining and Chemical Enterprise (MCE) is one of the leading Russian companies that deals exclusively with the dry storage of SNF. This company has implemented a long-term storage scheme. At the same time MCE faced the challenge of nondestructive monitoring of the degradation process of structural material of cask and its sealing with weld seam. Currently, X-ray testing is used for this purpose but in order to provide an effective nonradioactive method of monitoring MCE has initiated a collaborative R&D project with TPU supported by the Russian Government. Ultrasonic industrial tomography technique was proposed as the solution. The method is based on application of phased and sparse arrays transducer with real-time visualization algorithm. Received acoustic data is processed and realized by means of Sampling Phased Array technology which is a collaborative development of TPU and I-Deal Technology, GmbH. The multichannel ultrasonic set-up of immersion control was assembled for performing testing of seven experimental specimens with representative defects (side drill-holes, notches, natural welding flaws). X-ray tomography of high-resolution was chosen as the reference method. All indications were successfully reconstructed in B and C-scans and 3D image. The next step is to automate the monitoring procedure completely and to introduce an evaluation tool for current flaw state and prediction of its further behavior.

In this paper, we carried out a tomographic investigation of a chemical bubble column using ultrasonic sensor. The ultrasonic tomography sensing array was constructed to operate in transceiver-mode and was clamped on the exterior circumference of the column. The time-of-flight and arrival-time analysis was studied to obtain the signal information. Some experiments were carried out using known static profiles and were compared with the actual profiles. The findings showed promising results where the sensing array could detect gas bubble profiles down to 3mm in diameter, and the conclusions were made at the end of the paper.

Old masonries especially in the case of multi-leaf walls often present low compactness and very few links between the internal and external leaves. The injection of grouts in the core of the multi-leaf masonries is one of the techniques used most frequently for consolidation. In order to test the effectiveness of the filling process and the bonding of the grout to the masonry materials, ultrasonic tomography was conducted complemented with mechanical tests. The mechanical results showed good correlation with ultrasonic results and density gradients along the porous medium injected were obtained. Moreover, it was confirmed the importance of the bond properties of the interfaces (grout – porous medium particles) on the mechanical results. Regarding the ultrasonic tomography, the research demonstrated a correspondence between the characteristics of the porous media after the injection and the information displayed in the tomographs. Thus, it is proved that ultrasonic tomography is a useful technique to evaluate effectiveness of the grout injections, allowing an understanding of the ability of the injections to modify the physical and mechanical properties of an injected porous medium. This research has special relevance due to lack of information about the study of grout injection capacity in physical models (simulating the old masonries), through tomography and mechanical tests when compared to the amount of information that already exists in the case of study of grout injectability tests.

Lamb wave tomography (LWT) is a potential and efficient technique for non-destructive tomographic reconstruction of damage images in structural components or materials. A two-stage inverse algorithm proposed by the authors for quickly reconstructing the damage images was applied to hollow cylinders. An aluminum hollow cylinder with an internal surface pit and a Carbon Fiber Reinforced Plastic (CFRP) laminated hollow cylinder with an artificial internal surface damage were used to validate the proposed method. The results show that the present method is capable of successfully reconstructing the images of the above damages in a larger inspection area with much less experimental data compared to some conventional ultrasonic tomography techniques.

Ultrasonic tomography can be an important tool in the nondestructive evaluation of structural elements of wood and trees. Although wood is an anisotropic material, it is common to use an isotropic formulation in the tomographic processing. This paper presents a method that considers wood anisotropy in ultrasonic tomography. Christoffel and Hankinson equations were used to represent the orthotropic behavior of wood. In addition, the growth rings shape was also considered. The proposed method was validated through samples of wood with simulated non-homogeneities. The resulting tomograms were able to identify mortises when the specimen anisotropy was considered.

As today's standard screening methods frequently fail to detect breast cancer before metastases have developed, early diagnosis is still a major challenge. With the promise of high-quality volume images, three-dimensional ultrasound computer tomography is likely to improve this situation, but has high computational needs. In this work, we investigate the acceleration of the ray-based transmission reconstruction by a GPU-based implementation of the iterative numerical optimization algorithm TVAL3. We identified the regular and transposed sparse-matrix-vector multiply as the performance limiting operations. For accelerated reconstruction we propose two different concepts and devise a hybrid scheme as optimal configuration. In addition we investigate multi-GPU scalability and derive the optimal number of devices for our two primary use-cases: a fast preview mode and a high-resolution mode. In order to achieve a fair estimation of the speedup, we compare our implementation to an optimized CPU version of the algorithm. Using our accelerated implementation we reconstructed a preview 3D volume with 24,576 unknowns, a voxel size of (8?mm)3 and approximately 200,000 equations in 0.5?s. A high-resolution volume with 1,572,864 unknowns, a voxel size of (2mm)3 and approximately 1.6 million equations was reconstructed in 23?s. This constitutes an acceleration of over one order of magnitude in comparison to the optimized CPU version. We accelerate a ray-based 3D ultrasound CT reconstruction by GPU processing.By use-case optimized SpMV variants a speedup of one order of magnitude is obtained.We derive the optimal number of GPUs for reconstructions that do not fit on one GPU.A 3D-preview is reconstructed in 0.5 s, a high-resolution volume in 23 s.

A series of standard concrete beams with plastic P-T tendon ducts were tested at the University of Edinburgh using a range of NDT techniques including impact–echo (I–E), stack imaging of spectral amplitudes based on the impact–echo (SIBIE) and ultrasonic tomography. The findings were confirmed by comparison with earlier experiments undertaken using GPR. It has been argued that I–E cannot detect voids in plastic post-tensioned ducts readily. However it has been shown that whilst I–E is less effective on plastic ducts, the SIBIE analysis is more certain. This technique is easier to use than ultrasonic tomography and gives a credible evaluation. The paper goes on to analyse the above tests on a number of beams with confirmation for ultrasonic tomography and GPR.

Some concern exists over the safety and durability of the 600 post-tensioned bridges in the UK, and the much larger number worldwide. The objective of the work reported herein was to identify voiding in the metallic tendon ducts in these bridges. Voiding can give rise to two sets of problems: (a) possible ingress of chlorides, which would cause corrosion; and (b) a lack of redistribution of stress within the beam. It was against this background that it was important to first of all identify the extent of voiding in post-tensioned bridges. The new technique of ultrasonic tomography was used for the trials reported in this paper. Two test beams were examined: a 10 m long beam at the Transport Research Laboratory (TRL), Crowthorne, UK and a short test beam constructed at Stanger Science and Environment, Elstree, UK. The ducts in the TRL beam were 40 mm in diameter. This is smaller than would normally be encountered in a post-tensioned bridge beam. A more usual duct diameter would be 100–110 mm with a cover of around 125 mm. The second test beam at Stanger Science and Environment, Elstree contained 100-mm diameter ducts. The time-of-flight tomography data obtained demonstrated that it is a potentially highly successful method of investigating post-tensioned concrete beams. The method is somewhat time consuming and so should be used in conjunction with a simpler testing method, e.g. sonic impact-echo, which identifies areas of interest. The smaller the ducts to be investigated, the smaller the required distances between testing stations. This therefore significantly increases the testing time.

The purpose of this study was to investigate the clinical usefulness of the measurement of ultrasonic obstetric conjugate.In 209 pregnant women, ultrasonic obstetric conjugate was measured twice at 28 and 36 weeks of pregnancy. In 26 of these patients the measurement of obstetric conjugate by x-ray pelvimetry was also performed at 36 weeks of pregnancy because of medical indications. Obstetric outcome was investigated in association with ultrasonic obstetric conjugate. The relationship between ultrasonic obstetric conjugate and x-ray pelvimetry was investigated.Ultrasonic obstetric conjugate ranged from 10.7 to 15.1 cm. In 12 patients (5.7%) ultrasonic obstetric conjugate was less than 12 cm. Six of them (50.0%) underwent cesarean section because of dystocia. This percentage was significantly higher than 7.1% of the cesarean section rate (14 of 197) in patients with ultrasonic obstetric conjugate more than 12 cm (P.001). A close positive correlation was observed between ultrasonic obstetric conjugate and x-ray pelvimetry (r = 0.91; P.0001).We conclude that ultrasonic obstetric conjugate measurement is a safe and useful procedure in the prediction of dystocia.

In order to improve ultrasonic inspection, in terms of detection, sizing and characterization of defects, the French Atomic Energy Commission (CEA) has developed a dynamic adaptive focusing system called FAUST: Focusing Adaptive UltraSonic Tomography. This sytem is based on ultrasonic phased array transducers connected to a multi-channel acquisition system, which provides the delay and amplitude laws, allowing one to control dynamically the ultrasonic beam. This paper presents the general architecture of the system and some applications of it for defect characterization and improvement of the ultrasonic inspections.

1. 1. To evaluate the distribution patterns of subcutaneous fat and muscle 679 male and 950 female Japanese volunteers were investigated by means of ultrasonic tomography. 2. 2. With an increase in age the thickness of the anterior thigh muscle decreased, whilst subscapula muscle thickness was independent of age. 3. 3. In comparing a resident in a city (Tokyo) to a country resident (farmer in Yamagata) the arm muscle of a farmer was thicker than that of a cityman, while the thigh muscle was lower in the farmer. 4. 4. Muscle thickness is related to its cross-sectional area and the muscle area is affected by activity level in daily physical exercise. 5. 5. The present data indicate that the farmer makes less use of his legs than does the city dweller. 6. 6. There were significant correlation coefficients between fat thickness and HDL-C, i.e. the highest correlation was observed at the abdomen, suggesting that the fat thickness of the abdomen is one of the important factors for evaluating serum cholesterol level.

During the past two decades there have been significant developments in many aspects of acoustical imaging techniques for various applications. One aspect of this development has been the application of ultrasonic tomography to medical imaging and diagnosis instrumentation, and also to non-destructive evaluation of materials, to oceanographic systems for measurements of such factors as temperature and currents etc, and to seismic exploration. This paper reviews the theoretical and practical work in acoustical tomography to the present time.

A new approach to ultrasonic breast imaging is reported. Two-dimensional velocity distributions in tomographic slices transaxial to the breast are reconstructed from transmission time-of-flight projections. The data are displayed both as video images and in numeric format. Results of a clinical investigation in which both malignant and benign lesions have been observed are presented. The possibility of differential diagnosis of pathologies on the basis of velocity is discussed.

A method that includes diffraction effects is introduced for the tomographic reconstruction of the ultrasonic velocity distribution of an object. The reconstruction is in the spatial frequency domain and is based on two perturbation approximations to the wave equation. The two perturbation methods, small perturbation and smooth perturbation, are discussed with respect to their regions of validity. Examples of two-dimensional reconstructions based on simulated data are presented and the results discussed.

The report deals with 2 cases of heart tumors in which a commercial ultrasonic diagnostic equipment was used for tomography. In both cases we were successful in demonstrating the lesions. The visualization of subtle diagnostic details is ruled out by the rhythmical movements of the heart which cause blurring and superposition of signals.

Summary The application of diagnostic ultrasound to heart disease is a new field in medical and surgical practice and investigation. In this paper an ultrasonic scanning method of the inside of the heart, using intravenous ultrasonic probes, is described in principle and procedure, ultrasonic tomograms, by ppi display, are also presented. The C-scan with the intracardiac method produces a flat image of the interatrial septum and this method can produce a series of horizontal tomograms of the heart structure. In animal experiments, such structures as the right and left atrial walls, interatrial septums and right ventricles and aortas could be identified, suggesting the value of the method of diagnosis in clinical practice. Some of the clinical cases revealed that ultrasonic cardiac tomography with the ultrasonic intravenous probe could be a unique approach to patho-physiology and diagnosis of disorders of the heart. To nullify the effect of the heart movement a modified equipment has been introduced in which a servo-mechanism, to control the scanner, in synchronism with an ecg, is involved. The result is satisfactory.

Much ultrasonic diagnosis has the advantage that it requires no surgery, but if this advantage is forgone, scope for diagnosis can be extended. The authors describe examination of the liver by a p.p.i. display with a probe placed in the inferior vena cava via the femoral vein and a method of detecting and measuring an atrial septal defect (a.s.d.) with a probe inserted in the right atrium through the external jugular vein or the femoral vein. In detecting a.s.d. a C-scan technique is usually used. No harmful effects have been observed in either examination. This article is based on a paper which was presented at the 5th Conference on Medical Electronics at Liege in July, 1963

The mathematical model in ultrasound Computer tomography is the problem of identifying the potential in the Helmholtz equation. In high-energy collision theory the eikonal approximation is introduced to approach the far field for a given potential. In the present paper we adress the question of determining the potential from observed values of the far field; i.e., the inversion of the eikonal approximation. We assume that source and detector are moved in a fixed plane and finally we consider the limited aperture problem.

The ultrasonic appearance of pathological conditions in the male breast is similar to that encountered in the female breast. With grey scale echography, characteristic features associated with a particular condition can be recognized and an estimation made of the extent of the pathological involvement.