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Acoustic fault signal extraction via the line-defect phononic crystals

《机械工程前沿（英文）》 2022年第17卷第1期页码 10-10 doi: 10.1007/s11465-021-0666-y

摘要： Rotating machine fault signal extraction becomes increasingly important in practical engineering applications. However, fault signals with low signal-to-noise ratios (SNRs) are difficult to extract, especially at the early stage of fault diagnosis. In this paper, 2D line-defect phononic crystals (PCs) consisting of periodic acrylic tubes with slit are proposed for weak signal detection. The defect band, namely, the formed resonance band of line-defect PCs enables the incident acoustic wave at the resonance frequency to be trapped and enhanced at the resonance cavity. The noise can be filtered by the band gap. As a result, fault signals with high SNRs can be obtained for fault feature extraction. The effectiveness of weak harmonic and periodic impulse signal detection via line-defect PCs are investigated in numerical and experimental studies. All the numerical and experimental results indicate that line-defect PCs can be well used for extracting weak harmonic and periodic impulse signals. This work will provide potential for extracting weak signals in many practical engineering applications.

关键词： phononic crystals line-defect fault signal extraction acoustic enhancement

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Research progress of defect-engineered UiO-66(Zr) MOFs for photocatalytic hydrogen production

《能源前沿（英文）》 2021年第15卷第3期页码 656-666 doi: 10.1007/s11708-021-0765-9

摘要： In recent years, defect-engineered Zr-based UiO-66 metal-organic frameworks (UiO-66(Zr) metal-organic frameworks (MOFs)) have shown huge advantages in catalytic, functional materials, adsorption, and other fields due to their large surface areas, well-ordered porous structures, and flexible tailorability. It is extremely challenging to introduce defect sites in the synthesis of MOFs to regulate the physicochemical properties of materials such as (energy band structure, pore structure, etc.) to obtain an excellent performance. This paper reviews the recent research results of synthesis methods, characterization technologies, and application fields of defect-engineered UiO-66(Zr) MOFs materials in order to provide new insights to synthesize high-performance UiO-66(Zr) MOFs materials and promote the development of UiO-66(Zr) in various fields.

关键词： defect engineering metal-organic frameworks UiO-66 photocatalysis

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The defect-length effect in corrosion detection with magnetic method for bridge cables

Qiwei ZHANG, Rongya XIN

《结构与土木工程前沿（英文）》 2018年第12卷第4期页码 662-671 doi: 10.1007/s11709-018-0512-4

摘要：

Quantitative evaluation of the steel corrosion in cables is significant for the safe operation of cable-supported bridges. The magnetic flux (MF) examination shows great potential to detect the corrosion defect, or loss of metallic cross-sectional area (LMA). An LMA defect in steel cables can be measured accurately when it is longer than a certain length. However, for defects in early stage, where the length of corrosion area is short, the MF examination may produce unacceptable error. In this study, the effect of defect length on the MF examination for corrosion detection of bridge cables is investigated through theoretical analysis and model experiments. An original analytical model to quantify the influence of defect length is proposed based on the equivalent magnetic circuit method. Then, MF examination experiments are performed on a series of cable models with different defect lengths and locations to verify the analytical model. Further, parameter study is conducted based on the proposed analytical model to clarify the mechanism of the defect-length effect. The results show that the area loss caused by short corrosion damage will be underestimated if the defect-length effect is neglected, and this effect can be quantified efficiently with the proposed analytical model.

关键词： bridge cable corrosion detection defect length MF examination quantitative evaluation

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Single-electromagnet levitation for density measurement and defect detection

Yuhan JIA, Peng ZHAO, Jun XIE, Xuechun ZHANG, Hongwei ZHOU, Jianzhong FU

《机械工程前沿（英文）》 2021年第16卷第1期页码 186-195 doi: 10.1007/s11465-020-0608-0

摘要： This paper presents a single-electromagnet levitation device to measure the densities and detect the internal defects of antimagnetic materials. The experimental device has an electromagnet in its lower part and a pure iron core in the upper part. When the electromagnet is activated, samples can be levitated stably in a paramagnetic solution. Compared with traditional magnetic levitation devices, the single-electromagnet levitation device is adjustable. Different currents, electromagnet shapes, and distances between the electromagnet and iron core are used in the experiment depending on the type of samples. The magnetic field formed by the electromagnet is strong. When the concentration of the MnCl aqueous solution is 3 mol/L, the measuring range of the single-electromagnet levitation device ranges from 1.301 to 2.308 g/cm . However, with the same concentration of MnCl aqueous solution (3 mol/L), the measuring range of a magnetic levitation device built with permanent magnets is only from 1.15 to 1.50 g/cm . The single-electromagnet levitation device has a large measuring range and can realize accurate density measurement and defect detection of high-density materials, such as glass and aluminum alloy.

关键词： single-electromagnet electromagnetic levitation density measurement defect detection

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Cracking evolution behaviors of lightweight materials based on

Y. Luo, S. C. Wu, Y. N. Hu, Y. N. Fu

《机械工程前沿（英文）》 2018年第13卷第4期页码 461-481 doi: 10.1007/s11465-018-0481-2

摘要：

Damage accumulation and failure behaviors are crucial concerns during the design and service of a critical component, leading researchers and engineers to thoroughly identifying the crack evolution. Third-generation synchrotron radiation X-ray computed microtomography can be used to detect the inner damage evolution of a large-density material or component. This paper provides a brief review of studying the crack initiation and propagation inside lightweight materials with advanced synchrotron three-dimensional (3D) X-ray imaging, such as aluminum materials. Various damage modes under both static and dynamic loading are elucidated for pure aluminum, aluminum alloy matrix, aluminum alloy metal matrix composite, and aluminum alloy welded joint. For aluminum alloy matrix, metallurgical defects (porosity, void, inclusion, precipitate, etc.) or artificial defects (notch, scratch, pit, etc.) strongly affect the crack initiation and propagation. For aluminum alloy metal matrix composites, the fracture occurs either from the particle debonding or voids at the particle/matrix interface, and the void evolution is closely related with fatigued cycles. For the hybrid laser welded aluminum alloy, fatigue cracks usually initiate from gas pores located at the surface or sub-surface and gradually propagate to a quarter ellipse or a typical semi-ellipse profile.

关键词： fatigue crack initiation and growth fatigue damage mechanism damage tolerance defect characterization laser welded aluminum alloys

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Statistical analysis of recombination properties of the boron-oxygen defect in p-type Czochralski silicon

Nitin NAMPALLI,Tsun Hang FUNG,Stuart WENHAM,Brett HALLAM,Malcolm ABBOTT

《能源前沿（英文）》 2017年第11卷第1期页码 4-22 doi: 10.1007/s11708-016-0442-6

摘要： This paper presents the application of lifetime spectroscopy to the study of carrier-induced degradation ascribed to the boron-oxygen (BO) defect. Specifically, a large data set of p-type silicon samples is used to investigate two important aspects of carrier lifetime analysis: ① the methods used to extract the recombination lifetime associated with the defect and ② the underlying assumption that carrier injection does not affect lifetime components unrelated to the defect. The results demonstrate that the capture cross section ratio associated with the donor level of the BO defect ( ) vary widely depending on the specific method used to extract the defect-specific recombination lifetime. For the data set studied here, it was also found that illumination used to form the defect caused minor, but statistically significant changes in the surface passivation used. This violation of the fundamental assumption could be accounted for by applying appropriate curve fitting methods, resulting in an improved estimate of (11.90±0.45) for the fully formed BO defect when modeled using the donor level alone. Illumination also appeared to cause a minor, apparently injection-independent change in lifetime that could not be attributed to the donor level of the BO defect alone and is likely related to the acceptor level of the BO defect. While specific to the BO defect, this study has implications for the use of lifetime spectroscopy to study other carrier induced defects. Finally, we demonstrate the use of a unit-less regression goodness-of-fit metric for lifetime data that is easy to interpret and accounts for repeatability error.

关键词： Czochralski silicon boron-oxygen defect injection dependent lifetime spectroscopy goodness-of-fit repeatability error

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桥面铺装病害检测技术研究

郭成超,许朋飞,崔璨

《中国工程科学》 2017年第19卷第6期页码 38-43 doi: 10.15302/J-SSCAE-2017.06.006

摘要：

在桥梁的全生命周期中，桥面板是最容易出现病害的部分。桥面铺装层常常由于施工方法选择不当、混凝土老化、钢筋锈蚀等原因产生各种病害，这对桥梁结构、使用性能都会造成不利影响，因此有必要对相关病害进行检测，并对桥面质量做出相关评价。本文介绍了国内外四种主要无损检测方法（半电池电位法、探地雷达法、冲击回波法、红外热成像法）的工作原理以及相应的检测设备，利用其中一种或几种方法能准确评估桥面板的恶化情况，对桥面板状况进行快速、无损检测，为实现桥面铺装的准确检测提供技术支持，从而减少结构病害，延长桥梁的使用寿命。

关键词：桥面铺装病害无损检测

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Effect of cavity defect on the triaxial mechanical properties of high-performance concrete

Yanbin ZHANG; Zhe WANG; Mingyu FENG

《结构与土木工程前沿（英文）》 2022年第16卷第5期页码 600-614 doi: 10.1007/s11709-022-0821-5

摘要： The stress concentration of pipe structure or cavity defect has a great effect on the mechanical properties of the high-performance concrete (HPC) members in deep underground locations. However, the behaviour of HPC with cavities under triaxial compression is not understood, especially when pressurized liquid flows into the fractures from the cavity. This study aims to investigate the effect of the cavity and the confining pressure on the failure mechanisms, strengths, and deformation properties of HPC with a new experimental scheme. In this experiment, the pressurized liquid can only contact the surface of the sample in the cavity, while the other surfaces are isolated from the pressurized liquid. To further explore the effect of the cavity, the same experiments are also conducted on sealed and unsealed intact samples without a cavity. The failure modes and stress-strain curves of all types of the samples are presented. Under various confining pressures, all the samples with a cavity suffer shear failure, and there are always secondary tensile fractures initiating from the cavity sidewall. Additionally, it can be determined from the failure modes and the stress-strain curves that the shear fractures result from the sidewall failure. Based on the different effects of the cavity on the lateral deformations in different directions, the initiation of the sidewall fracture is well predicted. The experimental results show that both the increase of the confining pressure and the decrease of the cavity size are conducive to the initiation of sidewall fracture. Moreover, the cavity weakens the strength of the sample, and this study gives a modified Power-law criterion in which the cavity size is added as an impact factor to predict the strength of the sample.

关键词： high-performance concrete cavity conventional triaxial compression pressurized liquid modified power-law criterion

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Construction of defect-containing UiO-66/MoSe heterojunctions with superior photocatalytic performance

《化学科学与工程前沿（英文）》 2023年第17卷第4期页码 449-459 doi: 10.1007/s11705-022-2226-3

摘要： Metal–organic frameworks are recognized as promising multifunctional materials, especially metal–organic framework-based photocatalysts, which are considered to be ideal photocatalytic materials. Herein, a new type of UiO-66/MoSe₂ composite was prepared using the solvothermal method. The optimum composite was selected by adjusting the mass ratio of UiO-66 and MoSe₂. X-ray diffraction analysis showed that the mass ratio influenced the crystal plane exposure rate of the composite, which may have affected its photocatalytic performance. The composite is composed of ultra-thin flower-like MoSe₂ that wrapped around cubic UiO-66, a structure that increases the abundance of active sites for reactions and is more conducive to the separation of carriers. The photocatalytic properties of the composite were evaluated by measuring the degradation rate of Rhodamine B and the catalyst’s ability to reduce Cr(VI)-containing wastewater under visible light irradiation. Rhodamine B was decolorized completely in 120 min, and most of the Cr(VI) was reduced within 150 min. The photochemical mechanism of the complex was studied in detail. The existence of Mo⁶⁺ and oxygen vacancies, in addition to the Z-type heterojunction promote the separation of electrons and holes, which enhances the photocatalytic effect.

关键词： UiO-66/MoSe₂ photocatalysis dye-containing wastewater heavy metal wastewater oxygen vacancies

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Mechanism and characterization of microplastic aging process: A review

《环境科学与工程前沿（英文）》 2023年第17卷第8期 doi: 10.1007/s11783-023-1700-6

摘要：

● Methods for estimating the aging of environmental micro-plastics were highlighted.

关键词： Microplastics Aging Degradation Characterization Mechanism

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An experimental characterization of human torso motion

Daniele CAFOLLA,I-Ming CHEN,Marco CECCARELLI

《机械工程前沿（英文）》 2015年第10卷第4期页码 311-325 doi: 10.1007/s11465-015-0352-z

摘要：

The torso plays an important role in the human-like operation of humanoids. In this paper, a method is proposed to analyze the behavior of the human torso by using inertial and magnetic sensing tools. Experiments are conducted to characterize the motion performance of the human torso during daily routine operations. Furthermore, the forces acting on the human body during these operations are evaluated to design and validate the performance of a humanoid robot.

关键词： experimental biomechanics human torso analysis inertial sensor characterization

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Synthesis and characterization of norfloxacin biomonomer

Shengxiong DONG, Qiaoping CHEN, Hongfang XIE, Jianhua HUANG

《化学科学与工程前沿（英文）》 2011年第5卷第1期页码 55-59 doi: 10.1007/s11705-010-0537-2

摘要： A novel drug agent named norfloxacin biomonomer was developed in order to solve the problem of low drug content, uneven drug distribution, low molecular weight, and wide molecular weight distribution of polymer drug, based on polyurethane, which was used as an antibacterial agent to control the bacterial infection associated with biofilm formation on polymeric materials used in biologic environments. In this research, norfloxacin biomonomer was synthesized by esterifying the compound of norfloxacin. High-performance liquid chromatography system was used to analyze the purity of the final product and intermediate products, and Fourier transform infrared spectrometer and mass spectrum were used to verify the final product and intermediate products. The results showed that the objective product was developed successfully. The final product of norfloxacin biomonomer could be incorporated into the polyurethane as chain extender.

关键词： norfloxacin biomonomer synthesis characterization

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Microplastic and Nanoplastic Pollution: Characterization, Transport, Fate, and Remediation Strategies

《环境科学与工程前沿（英文）》 2022年第16卷第1期页码 12-12 doi: 10.1007/s11783-021-1446-y

摘要： Plastics continues to have a critical and essential role in human society such as food packing, product packages and building materials. In the meantime, it has been recognized as a global sustainability priority to study and mitigate pollution of plastics and the associated unknown impacts from ultrafine plastic particles. Microplastic (<5 mm) particles, for instance, have been detected in the aquatic environment globally and have raised scientific interests and environmental concerns. Microplastics (MPs) can enter rivers through a variety of pathways (e.g., wastewater effluent, breakdown of plastic debris) and can negatively impact aquatic organisms through both direct injection with food and indirect contamination from absorbed toxins. MPs can absorb heavy metals, pathogens, and organic contaminants, mainly persistent organic pollutants (POPs) that can be ingested by organisms and introduced into the food web. Meanwhile, MPs may also release potentially toxic substances (e.g., plasticizers, flame retardants and antimicrobial agents) during weathering and degradation. An increasing number of papers are being published during the last years related to the effects of MPs as well as with synergistic effects when associated with MPs and their byproducts such as nanometer sized plastics or nanoplastics. This special issue successfully garnered a collection of research articles that addressed various topics of microplastic or nanoplastic pollution, characteristic, and environmental fate in the water environment. Particularly, this issue reported the seasonable occurrence and distribution of microplastics in different regions (e.g., China and India) from high-latitude nature reserve to sediments and coastal marine environments. Moreover, new sampling and analytical methodologies (e.g., fluorescent labeling) to identify MPs in diver matrixes (e.g., wastewater, sediment, and biota) are critically reviewed. The information is critical for scientists, business leaders, legislators, and the public are to explore and develop solutions that lessen society’s plastic footprint. We thank all authors, reviewers, and editorial staff of FESE for their efforts and contributions to this special issue. Guest Editors: Wen Zhang Department of Civil and Environmental Engineering, New Jersey Institute of Technology (wen.zhang@njit.edu) Melissa Pasquinelli College of Natural Resources, North Carolina State University (melissa_pasquinelli@ncsu.edu) Yang Li School of the Environment Beijing Normal University (liyang_bnu@bnu.edu.cn)

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一种面向软件缺陷预测的相似性度量特征选择方法 Article

Qiao YU, Shu-juan JIANG, Rong-cun WANG, Hong-yang WANG

《信息与电子工程前沿（英文）》 2017年第18卷第11期页码 1744-1753 doi: 10.1631/FITEE.1601322

摘要：软件缺陷预测旨在通过历史数据和能反映软件模块特性的软件特征来发现潜在缺陷。然而，有的特征可能与类别（有缺陷或无缺陷）的相关性较高，有的特征可能是冗余的或无关的。针对软件缺陷预测中不同特征与类别的相关性差异，本文提出一种基于相似性度量（similarity measure, SM）的特征选择方法。首先，根据不同类样本间的相似性来更新特征权重；然后，按照特征权重值降序排列生成特征排序列表，并依次选取特征排序列表中的所有特征子集；最后，在KNN（k-nearest neighbor）模型上验证所有特征子集的分类性能，并采用AUC （area under curve）指标进行度量。在11个美国航空航天局（NASA）数据集上进行实验验证，结果表明，与其它四种特征选择方法相比，本文方法具有与之相当甚至更高的分类性能。

关键词：软件缺陷预测；特征选择；相似性度量；特征权重；特征排序列表

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Comprehensive kinetostatic modeling and morphology characterization of cable-driven continuum robots

《机械工程前沿（英文）》 2023年第18卷第3期 doi: 10.1007/s11465-023-0756-0

摘要： In-situ maintenance is of great significance for improving the efficiency and ensuring the safety of aero-engines. The cable-driven continuum robot (CDCR) with twin-pivot compliant mechanisms, which is enabled with flexible deformation capability and confined space accessibility, has emerged as a novel tool that aims to promote the development of intelligence and efficiency for in-situ aero-engine maintenance. The high-fidelity model that describes the kinematic and morphology of CDCR lays the foundation for the accurate operation and control for in-situ maintenance. However, this model was not well addressed in previous literature. In this study, a general kinetostatic modeling and morphology characterization methodology that comprehensively contains the effects of cable-hole friction, gravity, and payloads is proposed for the CDCR with twin-pivot compliant mechanisms. First, a novel cable-hole friction model with the variable friction coefficient and adaptive friction direction criterion is proposed through structure optimization and kinematic parameter analysis. Second, the cable-hole friction, all-component gravities, deflection-induced center-of-gravity shift of compliant joints, and payloads are all considered to deduce a comprehensive kinetostatic model enabled with the capacity of accurate morphology characterization for CDCR. Finally, a compact continuum robot system is integrated to experimentally validate the proposed kinetostatic model and the concept of in-situ aero-engine maintenance. Results indicate that the proposed model precisely predicts the morphology of CDCR and outperforms conventional models. The compact continuum robot system could be considered a novel solution to perform in-situ maintenance tasks of aero-engines in an invasive manner.

关键词： kinetostatic modeling morphology characterization variable friction continuum robots in-situ maintenance