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Process improvement in laser hot wire cladding for martensitic stainless steel based on the Taguchi method

Zilin HUANG,Gang WANG,Shaopeng WEI,Changhong LI,Yiming RONG

《机械工程前沿（英文）》 2016年 第11卷 第3期   页码 242-249 doi: 10.1007/s11465-016-0397-7

摘要：

Laser hot wire cladding, with the prominent features of low heat input, high energy efficiency, and high precision, is widely used for remanufacturing metal parts. The cladding process, however, needs to be improved by using a quantitative method. In this work, volumetric defect ratio was proposed as the criterion to describe the integrity of forming quality for cladding layers. Laser deposition experiments with FV520B, one of martensitic stainless steels, were designed by using the Taguchi method. Four process variables, namely, laser power (P), scanning speed (Vs), wire feed rate (Vf), and wire current (I), were optimized based on the analysis of signal-to-noise (S/N) ratio. Metallurgic observation of cladding layer was conducted to compare the forming quality and to validate the analysis method. A stable and continuous process with the optimum parameter combination produced uniform microstructure with minimal defects and cracks, which resulted in a good metallurgical bonding interface.

关键词： process optimization     Taguchi method     signal-to-noise (S/N) ratio     volumetric defect ratio     laser hot wire cladding    

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Optimization of phosphorus removal in uniFed SBR system for domestic wastewater treatment

Xuguang TANG, Shuying WANG, Yongzhen PENG

《环境科学与工程前沿（英文）》 2010年 第4卷 第4期   页码 475-481 doi: 10.1007/s11783-010-0244-8

摘要： The characteristic of phosphorus removal and appropriate change of the traditional operation modes were investigated in UniFed sequencing batch reactor (SBR) laboratory-scale apparatus (40 L), treating actual domestic wastewater with low ratios of C/N (2.57) and C/P (30.18), providing theoretical basis for actual application of wastewater treatment plant. UniFed SBR system with its unique operation mode had the distinct superiority of phosphorus removal. On this occasion, the effect of volumetric exchange ratio (VER) and the method of influent introduction for phosphorus removal were studied. When the carbon source became the limiting factor to phosphorus release, the higher the VER, the lower the phosphorus concentration in the effluent. Three different influent patterns, including one-time filling, four-time filling, and continuous filling with the same quantity of wastewater could increase the release rate of anaerobic phosphorus from 0.082 to 0.143 mg·P·(L·min) . Appropriate change of the traditional operation modes could optimize the efficiency of phosphorus removal. When the feed/ decant time was extended from 2 h to 4 h, the phosphorous removal efficiency increased from 59.93% to 88.45% without any external carbon source. In the mode of alternation of anoxic-aerobic (A/O) condition, phosphorous removal efficiency increased from 55.07% to 72.27% clearly. The carbon source in the influent can be used adequately, and denitrifying phosphorus removal was carried out in anoxic stage 2 (A2). This mode was optimal for the treatment of actual domestic wastewater with low C/N and C/P ratios.

关键词： UniFed sequencing batch reactor (SBR)     phosphorus removal     volumetric exchange ratio (VER)     alternation of anoxic-aerobic (A/O)     domestic wastewater    

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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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非饱和土坡危险含水量分析

张士林,王冬梅,李根华

《中国工程科学》 2004年 第6卷 第5期   页码 71-75

摘要：

介绍了由于雨水入渗，使非饱和土坡的含水量发生变化，而含水量正是与基质吸力有着直接的联系；同时通过分析条件水压力和非饱和土的容重与含水量的变化规律，得到基质吸力、饱和度、非饱和土容重与整个土坡的稳定性规律，也就是安全系数与含水量分布的规律。得出当土坡处于危险状况下的含水量分布，即当土坡中的含水量达到危险含水量时，土坡处于危险状态。因此，通过监测土坡的含水量的变化，获得土坡的稳定信息，为生产和安全提供保障。

关键词： 非饱和土     稳定性分析     降雨入渗     体积含水量     基质吸力    

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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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油压极值比与极值比效率

齐茂林

《中国工程科学》 2001年 第3卷 第4期   页码 73-75

摘要：

文章应用基础公式，推导液压系统油压极值比与极值比效率之间的关系式。该式说明，油压极值比越大，极值比效率就越低。提出了油压极值比是可以设计和选择的。

关键词： 油压极值比     极值比效率     液压系统    

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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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非饱和土的塑性体应变与剪应变的相互作用原理

王靖涛

《中国工程科学》 2007年 第9卷 第11期   页码 11-15

摘要：

将岩土塑性体应变与剪应变的相互作用原理拓展到了非饱和土领域。除了塑性体应变与剪应变的相互作用外，在非饱和土中出现了两类新的相互作用，吸力-塑性体应变和孔隙气压力-塑性体应变。吸力具有二重性质，其对塑性体应变作用包括两个相反的方面。基于吸力性质，阐明了非饱和土的一些独特的性质，诸如有效应力参数的物理涵义，吸力对体积变化和前期固结压力的影响和湿陷机理等。另外，应用拓展的塑性体应变与剪应变相互作用原理，从理论上证明了非饱和土的临界状态线是存在的和唯一的，以及它与应力历史无关。

关键词： 塑性体应变与剪应变的相互作用原理     非饱和土     基质吸力     有效应力原理    

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Controlling interstory drift ratio profiles via topology optimization strategies

《结构与土木工程前沿（英文）》 2023年 第17卷 第2期   页码 165-178 doi: 10.1007/s11709-022-0892-3

摘要： An approach to control the profiles of interstory drift ratios along the height of building structures via topology optimization is proposed herein. The theoretical foundation of the proposed approach involves solving a min–max optimization problem to suppress the maximum interstory drift ratio among all stories. Two formulations are suggested: one inherits the bound formulation and the other utilizes a p-norm function to aggregate all individual interstory drift ratios. The proposed methodology can shape the interstory drift ratio profiles into inverted triangular or quadratic patterns because it realizes profile control using a group of shape weight coefficients. The proposed formulations are validated via a series of numerical examples. The disparity between the two formulations is clear. The optimization results show the optimal structural features for controlling the interstory drift ratios under different requirements.

关键词： interstory drift ratio     aggregation function     bound formulation     min–max problem     topology optimization    

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Experimental evaluation and simulation of volumetric shrinkage and warpage on polymeric composite short

Jonnathan D. SANTOS,Jorge I. FAJARDO,Alvaro R. CUJI,Jaime A. GARCÍA,Luis E. GARZÓN,Luis M. LÓPEZ

《机械工程前沿（英文）》 2015年 第10卷 第3期   页码 287-293 doi: 10.1007/s11465-015-0346-x

摘要：

A polymeric natural fiber-reinforced composite is developed by extrusion and injection molding process. The shrinkage and warpage of high-density polyethylene reinforced with short natural fibers of Guadua angustifolia Kunth are analyzed by experimental measurements and computer simulations. Autodesk Moldflow® and Solid Works® are employed to simulate both volumetric shrinkage and warpage of injected parts at different configurations: 0 wt.%, 20 wt.%, 30 wt.% and 40 wt.% reinforcing on shrinkage and warpage behavior of polymer composite. Become evident the restrictive effect of reinforcing on the volumetric shrinkage and warpage of injected parts. The results indicate that volumetric shrinkage of natural composite is reduced up to 58% with fiber increasing, whereas the warpage shows a reduction form 79% to 86% with major fiber content. These results suggest that it is a highly beneficial use of natural fibers to improve the assembly properties of polymeric natural fiber-reinforced composites.

关键词： biocomposite     natural fiber     shrinkage     simulation     warpage    

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标题 作者 时间 类型 操作

Process improvement in laser hot wire cladding for martensitic stainless steel based on the Taguchi method

Zilin HUANG,Gang WANG,Shaopeng WEI,Changhong LI,Yiming RONG

期刊论文

Optimization of phosphorus removal in uniFed SBR system for domestic wastewater treatment

Xuguang TANG, Shuying WANG, Yongzhen PENG

期刊论文

Acoustic fault signal extraction via the line-defect phononic crystals

期刊论文

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

期刊论文

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

Qiwei ZHANG, Rongya XIN

期刊论文

Single-electromagnet levitation for density measurement and defect detection

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

期刊论文

非饱和土坡危险含水量分析

张士林,王冬梅,李根华

期刊论文

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

期刊论文

桥面铺装病害检测技术研究

郭成超,许朋飞,崔璨

期刊论文

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

Yanbin ZHANG; Zhe WANG; Mingyu FENG

期刊论文

油压极值比与极值比效率

齐茂林

期刊论文

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

期刊论文

非饱和土的塑性体应变与剪应变的相互作用原理

王靖涛

期刊论文

Controlling interstory drift ratio profiles via topology optimization strategies

期刊论文

Experimental evaluation and simulation of volumetric shrinkage and warpage on polymeric composite short

Jonnathan D. SANTOS,Jorge I. FAJARDO,Alvaro R. CUJI,Jaime A. GARCÍA,Luis E. GARZÓN,Luis M. LÓPEZ

期刊论文