Acoustic Assessment of Microstructural Deformation Mechanisms on a Cold Rolled Cu30Zn Brass.

The relationship between acoustic parameters and the microstructure of a Cu30Zn brass plate subjected to plastic deformation was evaluated. The plate, previously annealed at 550 °C for 30 min, was cold rolled to reductions ranging from 10% to 70%. Linear ultrasonic measurements were performed on each of the nine specimens, corresponding to the nine different reductions, using the pulse-echo method to record the times of flight of longitudinal waves along the thickness axis. Subsequently, acoustic measurements were conducted to determine the nonlinear parameter ß through second harmonic generation. Microstructural analysis, carried out by X-ray diffraction, Vickers hardness testing, and optical microscopy, revealed an increase in deformation twins, reaching a maximum at 40% thickness reduction. At higher deformations, the microstructure showed the generation and proliferation of shear bands, coinciding with a decrease in the twinning structure and an increase in dislocation density. The longitudinal wave velocity exhibited a 0.9% decrease at 20% deformation, attributed to dislocations and initial twin formation, followed by a continuous increase up to 2% beyond this point, resulting from the combined effects of twinning and shear banding. The nonlinear parameter ß displayed a notable maximum, approximately one order of magnitude greater than its original value, at 40% deformation. This peak correlates with a roughly tenfold increase in twinning fault probability at the same deformation level.

Assessing Swallowing Dysfunction Aggravation in Chronic Obstructive Pulmonary Disease Patients Using Ultrasonic Measurements With Swallowing Movement Parameters.

OBJECTIVE: To investigate the correlation between ultrasonic measurements of swallowing movement parameters and aggravation of swallowing dysfunction in patients with chronic obstructive pulmonary disease (COPD). METHODS: COPD patients with swallowing dysfunction (n = 120) and COPD patients with normal swallowing function (n = 100) treated in our hospital between January 2020 and January 2023 were included in observation and control groups, respectively. The correlation between ultrasonic measurements of swallowing movement parameters and COPD with swallowing dysfunction was analyzed. The observation group was divided into mild and severe groups according to their Gugging Swallowing Screen (GUSS) scores. The correlation between ultrasonic measurements of swallowing movement parameters and COPD exacerbation combined with swallowing dysfunction was analyzed. RESULTS: In the observation group, Hyoid muscle thickness, hyoid bone displacement, geniohyoid muscle movement distance, HLAS, and CSR were lower compared to the control group, negatively associated with COPD-related swallowing issues. Conversely, geniohyoid muscle movement time and minimum hyohyoid distance (NHLA) were higher in the observation group, positively correlated with COPD-related swallowing dysfunction. In COPD patients with swallowing problems, the severe group exhibited lower values for lingual muscle thickness, hyoid bone displacement, geniohyoid muscle movement distance, HLAS, and CSR compared to the mild group, while geniohyoid muscle movement time and NHLA were higher in the severe group. Receiver operating characteristic (ROC) curves were created, indicating the promising diagnostic utility of these parameters for assessing the presence and severity of swallowing dysfunction in COPD patients. CONCLUSION: The ultrasonic measurement of swallowing motion parameters can effectively assess swallowing dysfunction in COPD patients.

Ultrasonic Wave Mode-Based Application for Contactless Density Measurement of Highly Aerated Batters.

An ultrasonic wave mode-based method for density measurement in highly foamed batters was developed. Therefore, a non-contact ultrasonic sensor system was designed to generate signals for batch-wise processes. An ultrasonic sensor, containing a piezoelectric ceramic at the fundamental longitudinal frequency of 2 MHz, was used to take impedance measurements in pulse-echo mode. The ultrasonic signals were processed and analysed wave-mode wise, using a feature-driven approach. The measurements were carried out for different mixing times within a container, with the attached ultrasonic sensor. Within the biscuit batter, the change to the ultrasonic signals caused by density changes during the batter-mixing process was monitored (R2 = 0.96). The density range detected by the sensor ranges between 500 g/L and 1000 g/L. The ultrasonic sensor system developed also shows a reasonable level of accuracy for the measurements of biscuit batter variations (R2 > 0.94). The main benefit of this novel technique, which comprises multiple wave modes for signal features and combines these features with the relevant process parameters, leads to a more robust system as regards to multiple interference factors.

Low-temperature and elastic properties of the 1/1 Tsai-type quasicrystal approximant GdCd6investigated by ultrasonic measurements.

Low-temperature and elastic properties of the quasicrystal approximant GdCd6have been investigated by means of an ultrasonic measurement. Salient elastic anomalies were observed in the temperature and magnetic field dependence of the principal elastic constants, most probably being associated with the successive multiple magnetic phase transitions showing up at low temperatures. Based on the experimental data, a magnetic field vs temperature phase diagram was constructed. In a zero magnetic field, at least four phases appear to exist. However, the phase diagram both for the magnetic field applied forH//⟨100⟩andH//⟨110⟩is richer, and interestingly some phase boundaries correspond to the development of field-induced phases, leading to the intricate magnetic phase diagram possibly with multiple ordered phases. We discuss the elastic and electronic properties at low temperatures, and also the nature of the multiple magnetic phase transitions of GdCd6.

A unified model for large-scale thickness measurement of lubricating film based on ultrasonic lag phase slope.

A unified model based on the ultrasonic lag phase slope is developed for measuring the lubricating film thickness at a large scale. The ultrasonic lag phase of adjacent waves instead of the phase of overlapped waves is calculated as a function of the ultrasonic frequency and film thickness. The slope of the ultrasonic lag phase is determined correspondingly, which is linearly proportional to the lubricating film thickness. Both the finite element analysis and tests on the lubricating film thickness are performed to verify the proposed method. The results show that despite the fluctuations of the lag phase, the lag phase slope can be used for measuring the lubricating film thickness at a large scale from 0.1 µm to 170 µm.

Off-epicentral measurement of laser-ultrasonic shear-wave velocity and its application to elastic-moduli evaluation.

This study investigates the off-epicentral measurement system and methodology of laser-ultrasonic shear waves in the ablative regime, subsequently focusing on its application to the elastic-moduli evaluation. The proposed scheme facilitates the measurement of the shear-wave velocity by using the crosscorrelation of successive shear-wave pulse echoes, ensuring high reliability and reproducibility of the calculation results. Since the geometric diffraction induced by the finite dimensions of laser-ultrasonic source and receiver can increase the measurement error, far-field diffraction correction for the off-epicenter detection has been derived theoretically. Results have shown that the far-field diffraction correction error is of the same order as random error mainly caused by the finite observation time, signal-to-noise ratio and frequency bandwidth, and therefore cannot be neglected. The feasibility of this approach is then demonstrated by inspecting annealed commercial purity titanium plates. Good agreement of experimentally measured and theoretical values of shear-wave velocity confirms the validity of the proposed approach. The ultrasonic measurement-determined shear modulus shows a maximum deviation of ＋3.6% from the standard value of an isotropic material.

Effects of Castration Age on the Growth Performance of Nubian Crossbred Male Goats.

To determine the optimal timing for performing castration on goats, eighteen male Nubian crossbred goats were randomly assigned to two groups and castrated at 3 months and 6 months of age, respectively. Daily dry matter intake, biweekly body weights, and ultrasonic measurements of longissimus dorsi muscle growth were recorded. Results indicated that there was no significant difference between the two groups in terms of the blood parameter analysis (except testosterone, 0.36 ± 0.26 vs. 3.61 ± 0.27 ng/mL at 25 weeks old), economic analysis, and growth performance, including final body weight, total weight gain, average daily gain, total dry-matter intake, and feed conversion ratio (p > 0.05). However, the longissimus dorsi muscle depth of goats castrated at 6 months of age was significantly higher than that of goats castrated at 3 months of age. In conclusion, castration timing does not have a significant effect on the growth performance of goats; therefore, castrating goats at 3 months of age may be the best practice considering animal welfare and possible risks associated with late castration.

Predicting local material thickness from steady-state ultrasonic wavefield measurements using a convolutional neural network.

Acoustic steady-state excitation spatial spectroscopy (ASSESS) is a full-field, ultrasonic non-destructive evaluation (NDE) technique used to locate and characterize defects in plate-like structures. ASSESS generates a steady-state, single-tone ultrasonic excitation in a structure and a scanning laser Doppler Vibrometer (LDV) measures the resulting full-field surface velocity response. Traditional processing techniques for ASSESS data rely on wavenumber domain analysis. This paper presents the alternative use of a convolutional neural network (CNN), trained using simulated ASSESS data, to predict the local plate thickness at every pixel in the wavefield measurement directly. The defect detection accuracy of CNN-based thickness predictions are shown to improve for defects of greater size, and for defects with higher thickness reductions. The CNN demonstrates the ability to predict thickness accurately in regions where Lamb wave dispersion relations are complex or unknown, such as near the boundaries of a test specimen, so long as the CNN is trained on data that accounts for these regions. The CNN also shows generalizability to ASSESS experimental data, despite an entirely simulated training dataset.

Experimental investigation on hydrate dissociation in near-wellbore region caused by invasion of drilling fluid: ultrasonic measurement and analysis.

As we all know, development and utilization of clean energy is the only way for society to achieve its sustainable development. Although natural gas hydrates is a new type of clean energy, uncontrollable hydrate dissociation and accompanying methane leakage in drilling operation threaten drilling safety, as well as marine environment. However, the dissociation range of natural gas hydrates around wellbore cannot be reasonably determined in previous investigations, which may lead to the inaccurate estimation of borehole collapse and methane leakage. Then, the marine environment will be greatly damaged or affected. The purpose of the present work is to experimentally explore the dissociation characteristics of gas hydrates around wellbore in drilling operation and analyze the influence law and mechanism of various factors (such as hydrate saturation) on hydrate dissociation. It is expected to provide reference for exploring effective engineering measures to avoid the uncontrolled hydrate dissociation, borehole collapse and accompanying methane leakage. The experimental results demonstrate that acoustic velocity of hydrate-bearing sediment can be accurately expressed as quadratic polynomial of hydrate saturation, which is the theoretical basis for determination of hydrate saturation in subsequent experiments. Owing to the fact that hydrate dissociation is an endothermic reaction, hydrate dissociation gradually slows down in experiment. Throughout the experiment, the maximum dissociation rate at the beginning of the experiment is 8.69 times that at the end of the experiment. In addition, sensitivity analysis found that the increase in the stabilizer concentration in drilling fluid can inhibit hydrate dissociation more effectively than the increase in the hydrate saturation. Hydrate dissociation was completely inhibited when the concentration of soybean lecithin exceeds 0.60wt%, but hydrate dissociation definitely occurs in the near-wellbore region no matter what hydrate saturation is. In this way, based on the requirements of drilling safety and/or environment protection, hydrate dissociation and accompanying methane leakage can be controlled by designing and adjusting the stabilizer concentration in drilling fluid.

Ultrasonic Measurement of Axial Preload in High-Frequency Nickel-Based Superalloy Smart Bolt.

A high-frequency, piezoelectric thin-film sensor was successfully deposited on a nickel-based superalloy bolt by radio frequency magnetron sputtering to develop a smart, nickel-based superalloy bolt. Ultrasonic response characterization, high accuracy, and repeatability of ultrasonic measurement of axial preload in nickel-based superalloy smart bolts are reported here and were fully demonstrated. The axial preload in the nickel-based superalloy smart bolt was directly measured by the bi-wave method (TOF ratio between transverse and longitudinal-mode waves) without using the traditional integration of a longitudinal and shear transducer. A model concerning the bolt before and after tensioning was established to demonstrate the propagation and displacement distribution of the ultrasonic waves inside a nickel-based superalloy smart bolt. The measured A-scan signal presented significantly favorable features including a mixture of transverse and longitudinal mode waves, a pure and broad frequency spectrum which peaked at 17.14 MHz, and high measurement accuracy below 3% for tension of 4 kN-20 kN. For the temporal ultrasonic signal, the measurement envelopes were narrower than for the counterpart of the simulation, justifying the 'filtration' advantage of the high-frequency sensor. Both the TOF change of the single longitudinal-mode wave and the TOF ratio between transverse- and longitudinal-mode waves increased linearly with preload force in the range of 0 kN to 20 kN. Compared with the commercial piezoelectric probe, the proposed probe, based on the combination of a high-frequency, piezoelectric thin-film sensor and a magnetically mounted transducer connector, exhibited high tolerance to temperatures as high as 320 °C and high repeatability free from some interference factors such as bolt detection position change and couplant layer thickness. The results indicate that this system is a promising axial preload measurement system for high-temperature fasteners and connectors, and the proposed sensor is a practical, high-frequency ultrasonic sensor for non-destructive testing.

Ultrasonic optic nerve sheath diameter could improve the prognosis of acute ischemic stroke in the intensive care unit.

Objectives: Stroke patients with high intracranial pressure (ICP) may have poor prognosis. Non-invasive ultrasonic optic nerve sheath diameter (ONSD) could evaluate increased ICP. To investigate whether ONSD is valuable for prognosis of patients with acute ischemic stroke (AIS). Methods: AIS receiving intensive care were recruited with the Glasgow Coma Scale (GCS) score. Patients in group A underwent ultrasonic ONSD to assess ICP voluntarily, whereas group B without ONSD. Patients were followed up at discharge and once a week for 3 months with Glasgow Outcome Scale (GOS) score (four to five scores indicated good prognosis and one to three scores indicated poor prognosis). Results: Forty-nine patients were included. GCS scores did not differ significantly between groups A (26 patients) and B (8 ± 3 vs. 7 ± 3, p < 0.05). In group A, ONSD was 5.01 ± 0.48 mm, which correlated with GCS score (p < 0.05). At discharge, the GOS score was higher in group A than in group B (3.35 ± 1.35 vs. 2.57 ± 1.121, p = 0.034). The proportion of patients with a good prognosis was higher in group A than in group B (46.2% vs. 13.0%, p = 0.006). At discharge and after 3 months of follow-up, ONSD at admission was correlated with the GOS score in group A (r = -0.648 [p < 0.05] and -0.731 [p < 0.05], respectively). After 3 months of follow-up, the GOS score was higher in group A than group B (3.00 ± 1.673 vs. 2.04 ± 1.430, p < 0.05). The proportion of patients with a good prognosis was higher in group A than in group B (46.2% vs. 21.2%, p = 0.039). The Kaplan-Meier curve showed a higher rate of good prognosis in group A than in group B. ONSD (p < 0.05) was an independent predictor of poor prognosis. Conclusion: Non-invasive ultrasonic ONSD could be useful in improving the prognosis of patients with AIS receiving intensive care.

Research progress of corneal thickness measurement / 国际眼科杂志(Guoji Yanke Zazhi)

@#The thickness of the central cornea has an important influence on various eye diseases and operations such as keratoconus and other corneal diseases, glaucoma, and corneal refractive surgery. Obtaining accurate central corneal thickness is a topic that clinicians have been paying close attention to. It decides the operation method and operation parameters(cutting depth, cutting optical area size, <i>etc.</i>)of refractive surgery. Accurate measurement of central corneal thickness is a great concern to clinicians. At present, there are two kinds of measurement of corneal thickness: the first is ultrasonic measurement, such as traditional Type A ultrasonic corneal thickness meter and ultrasonic biological microscope; the second is optical measurement, including Pentacam, corneal endokeratoscope, optical coherence tomography, <i>etc</i>. Different measuring methods and instruments have their own advantages and disadvantages. However, the ultimate goal of developing corneal thickness measurement is easy operation and good repeatability. Therefore, based on the summarization of current clinically-used corneal thickness measurement instruments and of research progress of corneal thickness measurement, this paper aims at providing theoretical guide for clinical oculists.

Clinical value of left atrium-descending aorta distance measured on ultrasound images in the diagnosis of fetal total anomalous pulmonary venous connection / 中国基层医药

Objective:To investigate the clinical value of ultrasonic measurement of left atrium-descending aorta distance in the diagnosis of fetal total anomalous pulmonary venous connection (TAPVC).Methods:Pregnant women who underwent fetal anatomy scans in the second trimester of pregnancy in Central Hospital of Panyu District between January 2018 and June 2019 were included in this study using prospective and case-control study methods. The GE Voluson E8 and Philips EPIQ 7 ultrasound machines were used to measure the left atrium-descending aorta distance in the four-chamber view of the fetal heart. Pulmonary vein was carefully examined. Fetuses with isolated TAPVC were included in the positive group. The pregnancy outcomes were followed up during all participants. 200 healthy fetuses were randomly selected and included in the control group. The correlation between left atrium-descending aorta distance in normal fetuses and gestational weeks was analyzed. The average value of left atrium-descending aorta distances was compared between positive and control groups.Results:A total of 2 156 pregnant women received fetal anatomy scans, with the completion rate of 100%. Among them, 1 786 pregnant women were successfully followed up and 370 were lost to follow up. Among the 1 786 pregnant women, four fetuses were diagnosed with isolated TAPVC, consisting of three fetuses with intracardiac type TAPVC and one fetus with supracardiac type TAPVC, as confirmed by prenatal ultrasound. The left atrium-descending aorta distance in 200 normal fetuses was weakly related to gestational weeks ( r2 = 0.35, P < 0.000 1). The mean left atrium-descending aorta distance in the positive group was significantly greater than that in the control group (5.4 mm vs. 2.1 mm). Conclusion:Ultrasonic measurement of left atrial posterior spatial distance is simple and it is hardly affected by gestational weeks. It is innovative to diagnose TAPVC through quantitative analysis. The widening of left atrium-descending aorta distance has a certain value in suggesting fetal TAPVC. The sample size is small in this study. Multi-center studies involving larger sample sizes are needed to further validate the clinical significance of widened left atrium-descending aorta distance.

A modified surgical approach for hard and soft tissue reconstruction of severe periimplantitis defects: laser-assisted periimplant defect regeneration (LAPIDER).

BACKGROUND: The main problem in periimplantitis is often the combination of severe periimplant bone loss with a contaminated implant surface and an insufficient soft tissue situation. Classic surgical concepts with crestal access to the bony defect and debridement of the surface most often lead to partial defect regeneration and a soft tissue recession. An incision directly above the pathologic bony lesion is contrary to general surgical treatment rules. AIM: To overcome this problem, a new surgical concept was developed which allows to clean the implant surface, reconstruct the bony defect, and improve soft tissue height and thickness without cutting the papilla complex. This publication presents the innovative regenerative treatment approach for severe periimplantitis defects. MATERIAL AND METHODS: After diagnosis and non-surgical pre-treatment of a severe periimplantitis lesion, the following treatment protocol was applied: horizontal mucosal incision 5 mm apical to marginal mucosa, supraperiosteal preparation in apical direction, cutting through periosteum at the level of the implant apex, subperiosteal coronal flap elevation, exploration and cleaning of the periimplant defect, thorough debridement of the implant surface with the Er:YAG laser, subperiosteal grafting with connective tissue, grafting of the bony defect with autogenous bone chips from the mandibular ramus, and bilayered suturing of periosteum and mucosa. Implant survival, marginal bone levels, periimplant probing depths, recession, and facial mucosa thickness (PIROP ultrasonic measurement) were evaluated in a pilot case at 1-year follow-up examination. RESULTS: Inter-proximal, oral, and buccal marginal bone levels increased significantly to the level of the implant shoulder from pre-operative to 1-year follow-up examination. No signs of suppuration or periimplant infection were present. Probing depths and recession decreased significantly, while the facial mucosa thickness improved from pre-operative to final examination. CONCLUSIONS: Marginal bone levels and soft tissue improvement suggest feasibility for the regeneration of severe periimplant hard and soft tissue deficiencies by this new treatment approach. With the use of this concept, the simultaneous implant surface cleansing and improvement of hard and soft tissue seem to be possible and unfavorable postoperative exposition of titanium surface might be prevented. Comparative studies are planned to quantify the effects of this new surgical protocol.

Modeling Flaw Pulse-Echo Signals in Cylindrical Components Using an Ultrasonic Line-Focused Transducer with Consideration of Wave Mode Conversion.

Investigations on flaw responses can benefit the nondestructive testing of cylinders using line-focused transducers. In this work, the system function, the wave beam model, and a flaw scattering model are combined to develop an ultrasonic measurement model for line-focused transducers to predict flaw responses in cylindrical components. The system function is characterized using reference signals by developing an acoustic transfer function for line-focused transducers, which works at different distances for both planar and curved surfaces. The wave beams in cylindrical components are modeled using a multi-Gaussian beam model, where the effects of wave mode conversion and curvatures of cylinders are considered. Simulation results of wave beams are provided to analyze their propagation behaviors. The proposed ultrasonic measurement model is certified from good agreement between the experimental and predicted signals of side-drilled holes. This work provides guidance for evaluating the detection ability of line-focused transducers in cylindrical component testing applications.

Ultrasonic measurement of optic nerve sheath diameter: a non-invasive surrogate approach for dynamic, real-time evaluation of intracranial pressure.

The current study aimed to identify whether ultrasonographic measurements of optic nerve sheath diameter (ONSD) could dynamically and sensitively evaluate real-time intracranial pressure (ICP). ONSD measurements were performed approximately 5 min prior to and after a lumbar puncture (LP). A total of 84 patients (mean±SD age, 43.5±14.7 years; 41 (49%) men; 18 patients with elevated ICP) were included in the study. The Spearman correlation coefficients between the two observers were 0.779 and 0.703 in the transverse section and 0.751 and 0.788 in the vertical section for the left and right eyes, respectively. The median (IQR) change in ONSD (ΔONSD) and change in ICP (ΔICP) were 0.11 (0.05-0.21) mm and 30 (20-40) mmH2O, respectively, for all participants. With a reduction in cerebrospinal fluid pressure, 80 subjects (95%) showed an immediate drop in ONSD; the median (IQR) decreased from 4.13 (4.02-4.38) mm to 4.02 (3.90-4.23) mm (p<0.001). Significant correlations were found between ONSD and ICP before LPs (r=0.482, p<0.01) and between ΔONSD and ΔICP (r=0.451, p<0.01). Ultrasonic measurement of ONSD can reflect the relative real-time changes in ICP.

Influential factors and methods of evaluating the gingival biotype / 口腔疾病防治

@#Gingival biotypes are used to describe the morphological characteristics of periodontal tissue. According to thickness, the gingiva can be divided into thin and thick gingival biotypes. The gingival biotype has a wide range of influential factors and can be measured by various methods. In the process of oral treatment, to achieve good therapeutic effects and obtain a clear prognosis, it is particularly important to study the gingival biotype. This article reviews the influential factors and methods for assessing the gingival biotype. The results of literature review show that, factors influencing the gingival biotype include individual factors related to sex, age and ethnicity and oral soft and hard tissue characteristics related to crown shape, tooth position, alveolar bone thickness, keratinized gingival width and gingival papilla height. Gingival hypertrophy mainly occurs in young males and in people with square and round crowns, thicker alveolar bones and wider keratinized gingiva. With the development of methods for measuring the gingival biotype ranging from the traditional direct observation method, direct measurement methods and periodontal exploration methods to cone beam computed tomography and ultrasound have increased the accuracy of these measurements.

Influence of soft tissue grafting, orofacial implant position, and angulation on facial hard and soft tissue thickness at immediately inserted and provisionalized implants in the anterior maxilla.

BACKGROUND: Resorption of hard and soft tissues following immediate implant insertion is frequently reported. Data regarding the influencing factors on facial tissue thickness are rare. PURPOSE: This retrospective study investigated the impact of connective tissue grafting, the orofacial angulation and position of immediately inserted and provisionalized implants on the facial hard and soft tissue thickness in the anterior maxilla within a 1- to 5-year follow-up. MATERIAL AND METHODS: Implants with the prerequisite of having preoperative and postoperative cone beam computed tomography (CBCT) and a follow-up of 1 to 5 years were included. Facial bone deficiencies were grafted flaplessly with autogenous bone in all sites. In a subgroup of implants additional connective tissue grafting was performed, whereas the remaining implants were not grafted with soft tissue. The orofacial tooth and implant angulation, the change of horizontal position and the facial bone thickness were measured by CBCT, the facial mucosa thickness by an ultrasonic device. RESULTS: In total, 76 implants were placed in 55 patients. Sixty-nine sites showed a facial bone defect. Thirty-eight received a connective tissue graft additionally. All implants were still in function after a mean follow-up of 36 months. The mean thickness of the facial mucosa was 1.72 mm at 1 mm, 1.63 mm at 4 mm, 1.52 mm at 6 mm, and 1.66 mm at 9 mm apically to mucosal margin. The bone thickness was 0.02, 0.25, and 0.36 mm initially and 1.32, 1.26, and 1.11 mm finally at 1, 3, and 6 mm apically to implant shoulder level. Mixed model analysis revealed an impact of the preoperative bone status on the facial bone increase. The facial soft tissue thickness was significantly influenced by the gingival biotype. CONCLUSIONS: The results indicate that an initial severe hard tissue defect allows for significant bone regeneration. The facial soft tissue thickness is primarily influenced by the gingival biotype.

Accuracy of coded excitation methods for measuring the time of flight: Application to ultrasonic characterization of wood samples.

Ultrasound computed tomography (USCT) using the transmission mode is a way to detect and assess the extent of decay in wood structures. The resolution of the ultrasonic image is closely related to the different anatomical features of wood. The complexity of the wave propagation process generates complex signals consisting of several wave packets with different signatures. Wave paths, depth dependencies, wave velocities or attenuations are often difficult to interpret. For this kind of assessment, the focus is generally on signal pre-processing. Several approaches have been used so far including filtering, spectrum analysis and a method involving deconvolution using a characteristic transfer function of the experimental device. However, all these approaches may be too sophisticated and/or unstable. The alternative methods proposed in this work are based on coded excitation, which makes it possible to process both local and general information available such as frequency and time parameters. Coded excitation is based on the filtering of the transmitted signal using a suitable electric input signal. The aim of the present study was to compare two coded-excitation methods, a chirp- and a wavelet-coded excitation method, to determine the time of flight of the ultrasonic wave, and to investigate the feasibility, the robustness and the precision of the measurement of geometrical and acoustical properties in laboratory conditions. To obtain control experimental data, the two methods were compared with the conventional ultrasonic pulse method. Experiments were conducted on a polyurethane resin sample and two samples of different wood species using two 500 kHz-transducers. The relative errors in the measurement of thickness compared with the results of caliper measurements ranged from 0.13% minimum for the wavelet-coded excitation method to 2.3% maximum for the chirp-coded excitation method. For the relative errors in the measurement of ultrasonic wave velocity, the coded excitation methods showed differences ranging from 0.24% minimum for the wavelet-coded excitation method to 2.62% maximum for the chirp-coded excitation method. Methods based on coded excitation algorithms thus enable accurate measurements of thickness and ultrasonic wave velocity in samples of wood species.

Application of Machine Learning to Predict Macrosomia / 实用妇产科杂志

Objective:To improve the accuracy of prediction of macrosomia by application of machine learning.Methods:Ultrasound measurement data and fetal birth weight of macrosomia and normal birth weight neonates were collected during January 2015 to December 2016 in Mindong Hospital Affiliated to Fujian Medical University.Ultrasound built-in Hadlock formula,multiple linear regression,k-nearest neighbor,support vector machine,random forest were evaluated and compared to predict macrosomia using actual fetal birth weight as the gold standard.Results:The sensitivity of built-in Hadlock formula to predict macrosomia was 40.86％ and Youden index was 39.95％.The sensitivity of the multivariate linear regression was 60.22％ and the Youden index was 58.85％.The sensitivity of the k-nearest neighbor was 86.21％ and the Youden index was 75.10％.The sensitivity of the support vector machine was 86.21％ and the Youden index was 73.51％.The sensitivity of the random forest was 81.03％ and the Youden index was 71.51％.The Youden index of multivariate linear regression was significantly bigger than that of built-in Hadlock(u =3.64,P ＜0.001).The Youden index of k-nearest neighbor,support vector machine and random forest was significantly bigger and built-in Hadlock and multivariate linear regression (P＜0.001,P＜ 0.05).Conclusions:The machine learning is of high accuracy and great value of application.