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Time reversal method for guided wave inspection in pipes

DENG Fei, WU Bin, HE Cunfu

《机械工程前沿(英文)》 2008年 第3卷 第3期   页码 251-260 doi: 10.1007/s11465-008-0050-1

摘要: The application of the time reversal method in pipe-like structures based on finite element method (FEM) is investigated. A steel pipe model measuring 70 mm × 3.5 mm is used to analyze the reflection coefficient of the (0,2) mode with the time reversal process. Simulation results show that the time reversal array method is beneficial to the improvement of the signal-to-noise ratio of a guided wave inspection system. As the intercepting window is widened, more energy is included in re-emitted signals, which leads to a large reflection coefficient of the (0,2) mode. In parallel, a circumferential locating method based on the time reversal method is described. The time reversal process used for guided wave inspection leads to the temporal and spatial focusing. When the time reversal signals are re-emitted, the angular profile obtained at the axial location of the defect can be used to determine the circumferential location of the defect. Except for a pipe with one defect, the circumferential locating method has been verified on another pipe model with two defects. Meanwhile, the elements number of the time reversal array has been discussed for enhancing the discrimination of the defect circumferential location.

关键词: reversal process     beneficial     circumferential location     energy     number    

Development of an integrated structural health monitoring system for bridge structures in operational conditions

Xinqun ZHU, Hong HAO

《结构与土木工程前沿(英文)》 2012年 第6卷 第3期   页码 321-333 doi: 10.1007/s11709-012-0161-y

摘要: This paper presents an overview of development of an integrated structural health monitoring system. The integrated system includes vibration and guided-wave based structural health monitoring. It integrates the real-time heterogeneous sensor data acquiring system, data analysis and interpretation, physical-based numerical simulation of complex structural system under operational conditions and structural evaluation. The study is mainly focused on developing: integrated sensor technology, integrated structural damage identification with operational loads monitoring, and integrated structural evaluation with results from system identification. Numerical simulation and its implementation in laboratory show that the system is effective and reliable to detect local damage and global conditions of bridge structures.

关键词: integrated structural health monitoring     operational conditions     vibration and guided wave    

An investigation into the vibration of harmonic drive systems

M. Masoumi, H. Alimohammadi

《机械工程前沿(英文)》 2013年 第8卷 第4期   页码 409-419 doi: 10.1007/s11465-013-0275-5

摘要:

Harmonic drive systems are precise and specific transmission gear systems which are beneficial in terms of the high transmission ratio and almost zero backlash. These inherent and spectacular properties result in using this mechanism in robotic and space sciences where the precision and lightwieght play an important role. This paper presents a vibration analysis of harmonic drive systems using the shell theory. Equations of vibration for the flexspline and the circular spline of the system are derived and used to find the natural frequencies for both parts and, moreover, vibration response of the system under the operating condition is calculated. Also, obtained vibration equations are utilized to study the effects of different involved parameters such as the geometry of the flexspline and its gear tooth, eccentricity, and unbalancing on the vibrational behavior of the system.

关键词: harmonic drive system     strain wave gearing mechanism     vibration analysis     natural frequencies    

混沌工程学

龙运佳

《中国工程科学》 2001年 第3卷 第2期   页码 10-15

摘要:

世界是非线性的,线性只是其近似描述,混沌的发现表明:某些确定性非线性系统具有内在的随机行为。事实上,以往20年,无所不在的混沌现象几乎在每个学科都有所报道,如数学、物理学、化学,甚至社会科学。但理论研究学者的主要兴趣在于探究混沌的本质。与此同时,混沌的实际利用在许多工程领域受到重视,如信息工程、系统工程、医药工程、农业工程、电气工程、生物工程、机械工程、土木工程等。混沌工程学是一门新的研究混沌实际利用及其基本理论的非线性工程科学。文章对现代混沌工程学的定义、对象、概念、方法、理论与应用加以总结,并介绍其近来的进展及作者的工作。混沌工程学在国民经济与国防建设中研究的热点是:混沌分析技术,混沌控制技术与混沌生成技术。

关键词: 非线性     混沌     振荡     振动        

基于色散可调超构表面的宽带低剖面天线研究综述 Review Articles

Wei E. I. LIU, Zhi Ning CHEN, Xianming QING

《信息与电子工程前沿(英文)》 2020年 第21卷 第1期   页码 27-38 doi: 10.1631/FITEE.1900473

摘要: 超构表面支持传播导波和表面波,并表现出新颖的色散特性。通过调控其独特的色散特性、设置特殊的边界条件以及选用合适的激励机制,低剖面的超构表面天线也能激励起多个邻近的谐振模式以实现宽带定向辐射。本文首先介绍3类典型宽带低剖面色散可调超构表面天线及其工作原理,接着详细综述色散可调超构表面天线技术的研究进展,重点讨论小型化、圆极化、波束扫描等应用设计。这种新近发展的色散可调超构表面技术,不仅能为宽带低剖面天线设计提供解决方案,更显示其在新型天线技术研发中的巨大潜力。

关键词: 超构表面天线;色散调控;复合左右手色散特性;导波;表面波;宽带;低剖面    

Ultrasound-guided prostate percutaneous intervention robot system and calibration by informative particle

《机械工程前沿(英文)》 2022年 第17卷 第1期   页码 3-3 doi: 10.1007/s11465-021-0659-x

摘要: Applying a robot system in ultrasound-guided percutaneous intervention is an effective approach for prostate cancer diagnosis and treatment. The limited space for robot manipulation restricts structure volume and motion. In this paper, an 8-degree-of-freedom robot system is proposed for ultrasound probe manipulation, needle positioning, and needle insertion. A novel parallel structure is employed in the robot system for space saving, structural rigidity, and collision avoidance. The particle swarm optimization method based on informative value is proposed for kinematic parameter identification to calibrate the parallel structure accurately. The method identifies parameters in the modified kinematic model stepwise according to parameter discernibility. Verification experiments prove that the robot system can realize motions needed in targeting. By applying the calibration method, a reasonable, reliable forward kinematic model is built, and the average errors can be limited to 0.963 and 1.846 mm for insertion point and target point, respectively.

关键词: ultrasound image guidance     prostate percutaneous intervention     parallel robot     kinematics identification     particle swarm optimization     informative value    

图引导正则最小化的随机超梯度的交替方向方法 None

Qiang LAN, Lin-bo QIAO, Yi-jie WANG

《信息与电子工程前沿(英文)》 2018年 第19卷 第6期   页码 755-762 doi: 10.1631/FITEE.1601771

摘要: 提出并比较额外梯度交替方向的几种随机变体方法,称为带拉格朗日函数(SEGL)的随机超梯度交替方向法和带增广拉格朗日函数(SEGAL)的随机超梯度交替方向法。这些方法由两个大规模凸目标函数组成,可最小化图形引导的优化问题。机器学习中一些重要应用遵循图导引优化公式等作为线性回归、逻辑回归、Lasso结构化扩展以及结构化正则化逻辑回归的原则。通过融合逻辑回归和图形引导正则化回归,在几类数据集上进行了试验。试验结果表明所提算法优于其他竞争算法,且在实际应用中,SEGAL比SEGL性能更好。

关键词: 随机优化;图形引导最小化;超梯度法;融合逻辑回归;图导向正则化逻辑回归    

High-intensity focused ultrasound tumor ablation: Review of ten years of clinical experience

Lian ZHANG, Zhi-Biao WANG

《医学前沿(英文)》 2010年 第4卷 第3期   页码 294-302 doi: 10.1007/s11684-010-0092-8

摘要: High-intensity focused ultrasound (HIFU) is a technique to destroy tissue at depth within the body, selectively and without harming overlying and adjacent structures within the path of the beam because the ultrasonic intensity at the beam focus is much higher than that outside of the focus. Diagnostic ultrasound is the first imaging modality used for guiding HIFU ablation. In 1997, a patient with osteosarcoma was first successfully treated with ultrasound imaging-guided HIFU in Chongqing, China. Over the last decade, thousands of patients with uterine fibroids, liver cancer, breast cancer, pancreatic cancer, bone tumors, and renal cancer have been treated with ultrasound imaging-guided HIFU. Based on several research groups’ reports, as well as our ten-year clinical experience, we conclude that this technique is safe and effective in treating human solid tumors. HIFU is a promising technique. Most importantly, HIFU offers patients another alternative when those patients have no other treatment available.

关键词: high-intensity focused ultrasound (HIFU)     ultrasound imaging-guided HIFU (USgHIFU)     magnetic resonance imaging-guided HIFU (MRgHIFU)    

Entity and relation extraction with rule-guided dictionary as domain knowledge

《工程管理前沿(英文)》   页码 610-622 doi: 10.1007/s42524-022-0226-0

摘要: Entity and relation extraction is an indispensable part of domain knowledge graph construction, which can serve relevant knowledge needs in a specific domain, such as providing support for product research, sales, risk control, and domain hotspot analysis. The existing entity and relation extraction methods that depend on pretrained models have shown promising performance on open datasets. However, the performance of these methods degrades when they face domain-specific datasets. Entity extraction models treat characters as basic semantic units while ignoring known character dependency in specific domains. Relation extraction is based on the hypothesis that the relations hidden in sentences are unified, thereby neglecting that relations may be diverse in different entity tuples. To address the problems above, this paper first introduced prior knowledge composed of domain dictionaries to enhance characters’ dependence. Second, domain rules were built to eliminate noise in entity relations and promote potential entity relation extraction. Finally, experiments were designed to verify the effectiveness of our proposed methods. Experimental results on two domains, including laser industry and unmanned ship, showed the superiority of our methods. The F1 value on laser industry entity, unmanned ship entity, laser industry relation, and unmanned ship relation datasets is improved by +1%, +6%, +2%, and +1%, respectively. In addition, the extraction accuracy of entity relation triplet reaches 83% and 76% on laser industry entity pair and unmanned ship entity pair datasets, respectively.

关键词: entity extraction     relation extraction     prior knowledge     domain rule    

Vibration characteristics and machining performance of a novel perforated ultrasonic vibration platform

《机械工程前沿(英文)》 2023年 第18卷 第1期 doi: 10.1007/s11465-022-0730-2

摘要: Ultrasonic vibration-assisted grinding (UVAG) is an advanced hybrid process for the precision machining of difficult-to-cut materials. The resonator is a critical part of the UVAG system. Its performance considerably influences the vibration amplitude and resonant frequency. In this work, a novel perforated ultrasonic vibration platform resonator was developed for UVAG. The holes were evenly arranged at the top and side surfaces of the vibration platform to improve the vibration characteristics. A modified apparent elasticity method (AEM) was proposed to reveal the influence of holes on the vibration mode. The performance of the vibration platform was evaluated by the vibration tests and UVAG experiments of particulate-reinforced titanium matrix composites. Results indicate that the reasonable distribution of holes helps improve the resonant frequency and vibration mode. The modified AEM, the finite element method, and the vibration tests show a high degree of consistency for developing the perforated ultrasonic vibration platform with a maximum frequency error of 3%. The employment of ultrasonic vibration reduces the grinding force by 36% at most, thereby decreasing the machined surface defects, such as voids, cracks, and burnout.

关键词: ultrasonic vibration-assisted grinding     perforated ultrasonic vibration platform     vibration characteristics     apparent elasticity method     grinding force     surface integrity    

Study on wave rotor refrigerators

Yuqiang DAI, Dapeng HU, Meixia DING

《化学科学与工程前沿(英文)》 2009年 第3卷 第1期   页码 83-87 doi: 10.1007/s11705-009-0075-y

摘要: As a novel generation of a rotational gas wave machine, the wave rotor refrigerator (WRR) is an unsteady flow device used for refrigeration, in whose passages pressured streams directly contact and exchange energy due to the movement of pressure waves. In this paper, the working mechanism and refrigeration principle are investigated based on the one-dimensional unsteady flow theory. A basic limitation on main structural parameters and operating parameters is deduced and the wave diagram of WRR to guide designing is sketched. The main influential factors are studied through an experiment. In the DUT Gas Wave Refrigeration Studying and Development Center (GWRSDC) lab, the isentropic efficiency can now reach about 65%. The results show that the WRR is a feasible and promising technology in pressured gas refrigeration cases.

关键词: wave rotor     refrigeration     unsteady flow theory     wave diagram    

Prediction of the shear wave velocity

Amoroso SARA

《结构与土木工程前沿(英文)》 2014年 第8卷 第1期   页码 83-92 doi: 10.1007/s11709-013-0234-6

摘要: The paper examines the correlations to obtain rough estimates of the shear wave velocity from non-seismic dilatometer tests (DMT) and cone penetration tests (CPT). While the direct measurement of is obviously preferable, these correlations may turn out useful in various circumstances. The experimental results at six international research sites suggest that the DMT predictions of from the parameters (material index), (horizontal stress index), (constrained modulus) are more reliable and consistent than the CPT predictions from (cone resistance), presumably because of the availability, by DMT, of the stress history index .

关键词: horizontal stress index     shear wave velocity     flat dilatometer test     cone penetration test    

Recent development of vibration utilization engineering

WEN Bangchun

《机械工程前沿(英文)》 2008年 第3卷 第1期   页码 1-9 doi: 10.1007/s11465-008-0017-2

摘要: The utilization of vibration and wave, which was developed during the latter half of the 20th century, is one of the most valueable technology applications and has been rapidly developing recently . Because the technique is closely associated with industry and agriculture, it can create huge social and economical benefits and provide excellent services for society. Thus, due to its necessity in industry and daily life, extensive research has been devoted to vibration utillization engineering. In this paper, vibration utilization is classified into linear or non-linear vibrations, waves, and electric-magnetic oscillations. Their phenomena, patterns, and applications in nature and society are introduced. Some research results about vibration utilization engineering are described.

关键词: utilization engineering     non-linear     vibration     vibration utillization     utillization engineering    

Lamb wave propagation modeling for structure health monitoring

Xiaoyue ZHANG, Shenfang YUAN, Tong HAO

《机械工程前沿(英文)》 2009年 第4卷 第3期   页码 326-331 doi: 10.1007/s11465-009-0045-6

摘要: This study aims to model the propagation of Lamb waves used in structure health monitoring. A number of different numerical computational techniques have been developed for wave propagation studies. The local interaction simulation approach, used for modeling sharp interfaces and discontinuities in complex media (LISA/SIM theory), has been effectively applied to numerical simulations of elastic wave interaction. This modeling is based on the local interaction simulation approach theory and is finally accomplished through the finite elements software Ansys11. In this paper, the Lamb waves propagating characteristics and the LISA/SIM theory are introduced. The finite difference equations describing wave propagation used in the LISA/SIM theory are obtained. Then, an anisotropic metallic plate model is modeled and a simulating Lamb waves signal is loaded on. Finally, the Lamb waves propagation modeling is implemented.

关键词: Lamb wave     modeling     LISA/SIM theory     finite difference equation     finite element    

Application of python-based Abaqus preprocess and postprocess technique in analysis of gearbox vibration

Guilian YI, Yunkang SUI, Jiazheng DU

《机械工程前沿(英文)》 2011年 第6卷 第2期   页码 229-234 doi: 10.1007/s11465-011-0128-z

摘要:

To reduce vibration and noise, a damping layer and constraint layer are usually pasted on the inner surface of a gearbox thin shell, and their thicknesses are the main parameters in the vibration and noise reduction design. The normal acceleration of the point on the gearbox surface is the main index that can reflect the vibration and noise of that point, and the normal accelerations of different points can reflect the degree of the vibration and noise of the whole structure. The K-S function is adopted to process many points’ normal accelerations as the comprehensive index of the vibration characteristics of the whole structure, and the vibration acceleration level is adopted to measure the degree of the vibration and noise. Secondary development of the Abaqus preprocess and postprocess on the basis of the Python scripting programming automatically modifies the model parameters, submits the job, and restarts the analysis totally, which avoids the tedious work of returning to the Abaqus/CAE for modifying and resubmitting and improves the speed of the preprocess and postprocess and the computational efficiency.

关键词: Abaqus secondary development     Python language     vibration and noise reduction     K-S function     vibration acceleration level    

标题 作者 时间 类型 操作

Time reversal method for guided wave inspection in pipes

DENG Fei, WU Bin, HE Cunfu

期刊论文

Development of an integrated structural health monitoring system for bridge structures in operational conditions

Xinqun ZHU, Hong HAO

期刊论文

An investigation into the vibration of harmonic drive systems

M. Masoumi, H. Alimohammadi

期刊论文

混沌工程学

龙运佳

期刊论文

基于色散可调超构表面的宽带低剖面天线研究综述

Wei E. I. LIU, Zhi Ning CHEN, Xianming QING

期刊论文

Ultrasound-guided prostate percutaneous intervention robot system and calibration by informative particle

期刊论文

图引导正则最小化的随机超梯度的交替方向方法

Qiang LAN, Lin-bo QIAO, Yi-jie WANG

期刊论文

High-intensity focused ultrasound tumor ablation: Review of ten years of clinical experience

Lian ZHANG, Zhi-Biao WANG

期刊论文

Entity and relation extraction with rule-guided dictionary as domain knowledge

期刊论文

Vibration characteristics and machining performance of a novel perforated ultrasonic vibration platform

期刊论文

Study on wave rotor refrigerators

Yuqiang DAI, Dapeng HU, Meixia DING

期刊论文

Prediction of the shear wave velocity

Amoroso SARA

期刊论文

Recent development of vibration utilization engineering

WEN Bangchun

期刊论文

Lamb wave propagation modeling for structure health monitoring

Xiaoyue ZHANG, Shenfang YUAN, Tong HAO

期刊论文

Application of python-based Abaqus preprocess and postprocess technique in analysis of gearbox vibration

Guilian YI, Yunkang SUI, Jiazheng DU

期刊论文