Optimization of Nonlinear Lamb Wave Detection System Parameters in CFRP Laminates

Carbon fiber reinforced polymer (CFRP) laminates, as unique multifunctional materials, are widely applied in various aircraft, such as airliners, fighter planes, and space shuttles. To ensure aircraft safety during the production and application of CFRP laminates, it is necessary to improve the accuracy of nonlinear Lamb wave nondestructive testing to assess the damage in CFRP laminates caused by impact, high temperature, friction, corrosion, etc. In this study, the accuracy of nonlinear ultrasonic nondestructive testing was found to highly depend on the cycle number, output level and gain of the nonlinear ultrasonic detection system. Based on a single-factor experiment that considered the cycle number, output level, and gain of the amplifier as independent variables, a regression analysis was carried out on the fundamental wave amplitude value (A₁) and second harmonic amplitude value (A₂). Two response surface surrogate models were established to improve the accuracy of nonlinear Lamb wave nondestructive testing and to optimize the detection system parameters. The response surface models were verified via an analysis of variance (ANOVA), significance tests and an error statistical analysis. The results revealed the significant influence of these three factors on A₁ and A₂. Optimization of the response surface was achieved at eight cycles, an output level of 42 and a gain of 32 dB. Moreover, the nonlinear ultrasonic detection system achieved good operational stability, high accuracy and reliability under the above optimal parameter conditions. This approach provides scientific guidance for the accurate assessment of CFRP laminate damage.     

Non-contrast second harmonic imaging improves interobserver agreement and accuracy of dobutamine stress echocardiography in patients with impaired image quality

OBJECTIVE: To examine the influence of second harmonic imaging during dobutamine echocardiography on regional endocardial visibility, interobserver agreement in the interpretation of wall motion abnormalities, and diagnostic accuracy in patients with reduced image quality. DESIGN: Blinded comparison. SETTING: Tertiary care centre. PATIENTS: 103 consecutive patients with suspected coronary artery disease and impaired transthoracic image quality (>/= 2 segments with poor endocardial delineation). METHODS: Fundamental and second harmonic imaging were performed at each stage of a dobutamine stress echocardiography. Coronary angiography was undertaken within three weeks of dobutamine echocardiography in 75 patients. MAIN OUTCOME MEASURES: Evaluation of regional endocardial visibility (scoring from 0 = poor to 2 = good) and of segmental wall motion abnormalities for both modalities separately. A second blinded examiner analysed 70 studies to determine interobserver agreement. RESULTS: Mean (SD) visibility score for all segments was 1.2 (0.4) using fundamental imaging and 1.7 (0.2) using second harmonic imaging at rest (p < 0.001), and 1.1 (0.4) v 1.6 (0.3), respectively, at peak dobutamine dose (p < 0.001). The average number of segments with poor endocardial visibility was lower for second harmonic than for fundamental imaging (0.6 (1.1) v 3.8 (2.6) at rest, p < 0.001; 0.9 (1.3) v 4.3 (2.9) at peak dose, p < 0.001). Improvement was most pronounced in all lateral and anterior segments. The kappa value for identical study interpretation increased from 0. 40 to 0.69 (p < 0.05). Sensitivity for the diagnosis of coronary artery disease was 64% using fundamental imaging versus 92% using harmonic imaging (p < 0.001), while specificity remained unchanged at 75% for both imaging modalities. CONCLUSIONS: Second harmonic imaging enhances endocardial visibility during dobutamine echocardiography. Consequently, interobserver agreement on stress echocardiography interpretation and diagnostic accuracy are significantly improved compared to fundamental imaging. Thus, in difficult to image patients, dobutamine echocardiography should be performed using second harmonic imaging.     

The human brain processes hierarchical structures of meter and harmony differently: Evidence from musicians and nonmusicians

The processing of temporal structure has been widely investigated, but evidence on how the brain processes temporal and nontemporal structures simultaneously is sparse. Using event-related potentials (ERPs), we examined how the brain responds to temporal (metric) and nontemporal (harmonic) structures in music simultaneously, and whether these processes are impacted by musical expertise. Fifteen musicians and 15 nonmusicians rated the degree of completeness of musical sequences with or without violations in metric or harmonic structures. In the single violation conditions, the ERP results showed that both musicians and nonmusicians exhibited an early right anterior negativity (ERAN) as well as an N5 to temporal violations (“when”), and only an N5-like response to nontemporal violations (“what”), which were consistent with the behavioral results. In the double violation condition, however, only the ERP results, but not the behavioral results, revealed a significant interaction between temporal and nontemporal violations at a later integrative stage, as manifested by an enlarged N5 effect compared to the single violation conditions. These findings provide the first evidence that the human brain uses different neural mechanisms in processing metric and harmonic structures in music, which may shed light on how the brain generates predictions for “what” and “when” events in the natural environment.     

超声刀在颈淋巴清扫术中的临床应用

目的 :探讨超声刀技术在口腔颌面头颈部鳞癌施行颈淋巴清扫术中的临床应用价值和手术技巧。方法 :2007-02—2012-12期间,随机交叉选取口腔黏膜鳞状细胞癌432例患者,分为超声刀组(216例)和电刀组(216例)。比较2组的手术时间、失血量、术后24h引流量、术后住院天数以及术后并发症的发生等项目。结果:与电刀组相比较,超声刀组在手术时间、术中失血量、24h引流量、住院天数等方面具有明显优势,经统计学分析,P<0.05为差异有统计学意义。结论:应用超声刀技术施行颈淋巴清扫术,具有传统高频电刀所不具有的组织分离和切割、凝固止血三种功能合一体的优点,实用手术技巧与超声刀技术联合应用,可使颈淋巴清扫完全达到根治性要求。是一种值得临床推广,且有应用前景的颈淋巴清扫治疗策略。     

腹腔镜手术使用超声刀对手术室二氧化碳浓度影响研究

将行经腹腔镜胆囊切除术患者80例,随机分为超声刀组(A组),高频电刀组(B组)。分别于手术开始前15min、手术开始后15 min、手术开始后30 min监测手术室内CO2浓度。与手术开始前15 min比较,两组手术室内CO2浓度均升高(P0.05);手术开始后15 min及30 min,A组室内CO2浓度较B组低(P0.05)。腹腔镜手术中使用超声刀可明显降低手术室内CO2浓度。     

小针刀治疗肛裂的临床研究

目的 通过随机对照研究,比较小针刀侧方内括约肌切断术和后方内括约肌切断术对肛裂治疗的疗效和安全性.方法 观察96例肛裂患者,其中48例采用小针刀侧方内括约肌切断术(观察组),48例采用后方内括约肌切断术(对照组),比较两组疗效、术后疼痛评分、术后并发症、恢复正常生活时间、伤口愈合时间、伤口愈合等级和术后1年复发率.结果...     

Real‐time contrast‐enhanced ultrasound determination of microvascular blood volume in abdominal subcutaneous adipose tissue in man. Evidence for adipose tissue capillary recruitment

The adipose tissue metabolism is dependent on its blood perfusion. During lipid mobilization e.g. during exercise and during lipid deposition e.g. postprandial, adipose tissue blood flow is increased. This increase in blood flow may involve capillary recruitment in the tissue. We investigated the basic and postprandial microvascular volume in adipose tissue using real‐time contrast‐enhanced ultrasound (CEU) imaging in healthy normal weight subjects. In nine subjects, CEU was performed in abdominal subcutaneous adipose tissue and in the underlying skeletal muscle after a bolus injection of ultrasound contrast agent to establish the reproducibility of the technique. In nine subjects, the effect of an oral glucose load on blood flow and microvascular volume was measured in abdominal subcutaneous adipose tissue and forearm skeletal muscle. ¹³³Xe washout and venous occlusion strain‐gauge plethysmography was used to measure the adipose tissue and forearm blood flow, respectively. Ultrasound signal intensity of the first plateau phases was 27 ± dB in the abdominal subcutaneous adipose tissue and 18 ± 2dB (P<0·05) in the underlying skeletal muscle. The reproducibility of the measurements was good with a 4% coefficient of variation in both tissues. Blood flow and the change in signal intensity as a measure of the microvascular volume increased significantly and simultaneously in abdominal subcutaneous adipose tissue after glucose intake. The forearm blood flow and muscle signal intensity remained constant. It is concluded that the microvascular volume and changes in volume in abdominal subcutaneous adipose tissue can be assessed using CEU with good reproducibility. Postprandial capillary recruitment takes place in abdominal subcutaneous adipose tissue.     

基于脉冲反相技术的医用高频超声组织谐波信息提取技术的研究

本文在所研制的高频超声数字编码发射和宽带接收系统的基础上,利用基频为20 MHz、35 MHz和50 MHz的宽带超声换能器,进行了脉冲反相技术高频超声谐波提取方法的实验研究.结果表明.采用本方法,可有效地抑制基波的影响.同时能有效提高高频谐波信号的幅度,较传统的RF滤波法分离谐波具有明显的优势.     

腹腔镜下全子宫切除术中超声刀的应用价值

目的:探讨超声刀在腹腔镜下全子宫切除术中的应用价值。方法:126例子宫良性病变患者在腹腔镜下分别应用超声刀和双极电凝进行全子宫切除术,比较术中出血量、手术时间、术后平均住院日及肛门排气时间。结果:超声刀组的平均手术时间、术中平均出血量显著少于双极电凝组(P<0.01),术后平均住院日及肛门排气时间在两组间差异无显著性(P>0.05)。结论:超声刀可用于妇科腹腔镜全子宫切除术,由于其操作简单、安全可靠,值得推广。