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Local arc discharge mechanism and requirements of power supply in micro-arc oxidation of magnesium alloy

Ming CHEN, Yuezhou MA, Yuan HAO,

《机械工程前沿（英文）》 2010年 第5卷 第1期   页码 98-105 doi: 10.1007/s11465-009-0088-8

摘要： To study the requirements of the power supply in micro-arc oxidation (MAO) of magnesium alloy, many experiments were performed under the DC, unipolar, and ambipolar pulse output modes. Based on the experimental results and electric arc theory, the separate local arc discharge mechanism was put forward. It is considered that magnesium MAO process consists of three stages including anodic oxidation, micro-arc oxidation, and large-arc discharge in turn with increasing source voltage. The MAO film is composed of metal oxides that resulted from numerous discrete local arc discharges, which accumulate the non-equilibrium structure after undergoing sudden heating and cooling cycles. Separate local arc discharge is caused by the process in which the oxygen-based gas is ionized in the conduct channel bearing electric field intensity, changed from insulator to conductor that presents sharp negative resistance effect, and produced partially high temperature to ignite locally metal oxidation. The local arc discharge model is described as four courses: gas created from electrolysis, arc discharge, metals oxidization, and cooling and shrinking of oxides. The purpose of pulse supply is to inhibit the large-arc discharge by intervening proper cooling time, which cannot be actualized by a unipolar pulse mode because of the strong capacitive load characteristics but can be reached by an ambipolar pulse supply because the negative pulse period acts as cooling time. Using a discharge loop to remove the influence of load capacitive, a new type of pulse power supply for MAO is developed, so that the large-arc problem is resolved effectively, the film-forming efficiency is improved, and the pollution of the film and electrolyte caused by negative voltage is avoided.

关键词： micro-arc oxidation     local arc discharge     pulse power supply     magnesium alloy    

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Plasma-enabled healing of graphene nano-platelets layer

Xiuqi Fang, Carles Corbella, Denis B. Zolotukhin, Michael Keidar

《化学科学与工程前沿（英文）》 2019年 第13卷 第2期   页码 350-359 doi: 10.1007/s11705-018-1787-7

摘要： Graphene platelet networks (GPNs) were deposited onto silicon substrates by means of anodic arc discharge ignited between two graphite electrodes. Substrate temperature and pressure of helium atmosphere were optimized for the production of the carbon nanomaterials. The samples were modified or destroyed with different methods to mimic typical environments responsible of severe surface degradation. The emulated conditions were performed by four surface treatments, namely thermal oxidation, substrate overheating, exposition to glow discharge, and metal coating due to arc plasma. In the next step, the samples were regenerated on the same substrates with identical deposition technique. Damaging and re-growth of GPN samples were systematically characterized by scanning electron microscopy and Raman spectroscopy. The full regeneration of the structural and morphological properties of the samples has proven that this healing method by arc plasma is adequate for restoring the functionality of 2D nanostructures exposed to harsh environments.

关键词： graphene platelet networks     anodic arc discharge     plasma healing     scanning electron microscopy     Raman spectroscopy    

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Stress field near circular-arc interface crack tip based on electric saturation concept

Longchao DAI, Xinwei WANG

《机械工程前沿（英文）》 2009年 第4卷 第3期   页码 320-325 doi: 10.1007/s11465-009-0042-9

摘要： Within the framework of nonlinear electroelasticity, the anti-plane problem of a circular-arc interfacial crack between a circular piezoelectric inhomogeneity and an infinite piezoelectric matrix subjected to a far-field uniform loading is investigated by an electrical strip saturation model, the complex variable method, and the method of analytical continuation. Explicit closed form expressions for the complex potentials in both the matrix and the inclusion, and the stress intensity factor at the crack tip are presented. Comparison with some related solutions based on the linear electroelastic theory shows the validity of the present solutions

关键词： piezoelectric material     arc crack     strip saturation     stress intensity factor    

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Development of a new wear resistant coating by arc spraying of a steel-based cored wire

Lidong ZHAO, Pia KUTSCHMANN, Binyou FU, Dingyong HE

《机械工程前沿（英文）》 2009年 第4卷 第1期   页码 1-4 doi: 10.1007/s11465-009-0012-2

摘要： In the present study, a cored wire of 304 L stainless steel as sheath material and NiB and WC-12Co as filler materials was designed and deposited to produce a new wear resistant coating containing amorphous phase by arc spraying. The microstructure of the coating was investigated. The porosity and hardness of the coating were determined. The wear performance of the coating was evaluated. The XRD and TEM analyses showed that there are high volume of amorphous phase and very fine crystalline grains in the coating. DTA measurements revealed that the crystallization of the amorphous phase occurred at 579.2°C. Because metallurgical processes for single droplets were non-homogenous during spraying, the lamellae in the coating have different hardness values, which lie between about 700 and 1250 HV . The abrasive wear test showed that the new Fe-based coating was very wear resistant.

关键词： amorphous phase     arc spraying     microstructure     wear     cored wire    

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Submerged arc plasma system combined with ozone oxidation for the treatment of wastewater containing

《环境科学与工程前沿（英文）》 2021年 第15卷 第5期 doi: 10.1007/s11783-020-1384-0

摘要：

• Submerged arc plasma was introduced in terms of wastewater treatment.

关键词： Thermal plasma     Submerged arc plasma     Wastewater     Ozone     Phenol     Highly energetic electron    

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Experimental and modeling studies on installation of arc sprayed Zn anodes for protection of reinforced

Xianming SHI

《结构与土木工程前沿（英文）》 2016年 第10卷 第1期   页码 1-11 doi: 10.1007/s11709-016-0312-7

摘要： Arc sprayed zinc (Zn) anode on concrete surfaces has been an emerging technology for protecting reinforced concrete structures from rebar corrosion in coastal environments. Many cathodic protection (CP) systems with arc sprayed Zn anodes will reach or exceed their design life in the near future and thus may function improperly or insufficiently, making it necessary to replace the aged anodes. However, prior to this study, little was known about the most effective profile for the concrete surface, for either new concrete or old concrete with existing Zn anodes removed. This work develops criteria to properly prepare the concrete surface before the application of new Zn anode. Experimental studies were conducted both in the laboratory and for a field structure in Oregon. Artificial neural network was used to achieve better understanding of the complex cause-and-effect relationships inherent in the Zn-mortar or Zn–concrete systems and was successful in finding meaningful, logical results from the bond strength data. The goal is to achieve strong initial bond strength of new Zn to concrete, which is essential for long-term performance of the CP system. The results from this case study suggest that it is necessary to adjust the anode removal and surface sandblasting based on the electrochemical age of the existing concrete. In all cases of sandblasting, minimize the exposure of large aggregates (e.g., those bigger than 19 mm in diameter).

关键词： arc sprayed Zn     anode replacement     reinforced concrete     bridge preservation     neural networks     surface profile    

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Mathematical model and manufacture programming of loxodromic-type normal circular-arc spiral bevel gear

Zhenyun DUAN, Houjun CHEN, Zhilan JU, Jian LIU

《机械工程前沿（英文）》 2012年 第7卷 第3期   页码 312-321 doi: 10.1007/s11465-012-0308-5

摘要：

In this paper, loxodromic-type normal circular-arc spiral bevel gear is proposed as a novel application of the circular-arc tooth profile at the gear transmission with intersecting axes. Based on the principle of molding-surface conjugation, the study develops a mathematical model for the tooth alignment curve and the computational flow at the design stage to enable the generation of the tooth surface. Machining of the tooth surface is then carried out to determine the interference-free tool path of the numerical control (NC). Moreover, a pair of loxodromic-type normal circular-arc spiral bevel gears is manufactured on computer numerical control (CNC) machine tools. The proposed theory and method are experimentally investigated, and the obtained results primarily reflect the superior performance of the proposed novel gear.

关键词： loxodrome     circular-arc tooth profile     Wildhaber-Novikov (W-N) gear     spiral bevel gear    

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High-order phase-field model with the local and second-order max-entropy approximants

Fatemeh AMIRI

《结构与土木工程前沿（英文）》 2019年 第13卷 第2期   页码 406-416 doi: 10.1007/s11709-018-0475-5

摘要： We approximate the fracture surface energy functional based on phase-field method with smooth local maximum entropy (LME) and second-order maximum entropy (SME) approximants. The higher-order continuity of the meshfree methods such as LME and SME approximants allows to directly solve the fourth-order phase-field equations without splitting the fourth-order differential equation into two second-order differential equations. We will first show that the crack surface functional can be captured more accurately in the fourth-order model with smooth approximants such as LME, SME and B-spline. Furthermore, smaller length scale parameter is needed for the fourth-order model to approximate the energy functional. We also study SME approximants and drive the formulations. The proposed meshfree fourth-order phase-field formulation show more stable results for SME compared to LME meshfree methods.

关键词： second-order maximum entropy     local maximum entropy     second- and fourth-order phase-field models     B-spline    

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Local uncorrelated local discriminant embedding for face recognition

Xiao-hu MA,Meng YANG,Zhao ZHANG

《信息与电子工程前沿（英文）》 2016年 第17卷 第3期   页码 212-223 doi: 10.1631/FITEE.1500255

摘要： The feature extraction algorithm plays an important role in face recognition. However, the extracted features also have overlapping discriminant information. A property of the statistical uncorrelated criterion is that it eliminates the redundancy among the extracted discriminant features, while many algorithms generally ignore this property. In this paper, we introduce a novel feature extraction method called local uncorrelated local discriminant embedding (LULDE). The proposed approach can be seen as an extension of a local discriminant embedding (LDE) framework in three ways. First, a new local statistical uncorrelated criterion is proposed, which effectively captures the local information of interclass and intraclass. Second, we reconstruct the affinity matrices of an intrinsic graph and a penalty graph, which are mentioned in LDE to enhance the discriminant property. Finally, it overcomes the small-sample-size problem without using principal component analysis to preprocess the original data, which avoids losing some discriminant information. Experimental results on Yale, ORL, Extended Yale B, and FERET databases demonstrate that LULDE outperforms LDE and other representative uncorrelated feature extraction methods.

关键词： Feature extraction     Local discriminant embedding     Local uncorrelated criterion     Face recognition    

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Making central-local relations work: Comparing America and China environmental governance systems

Dan GUTTMAN, SONG Yaqin

《环境科学与工程前沿（英文）》 2007年 第1卷 第4期   页码 418-433 doi: 10.1007/s11783-007-0068-3

摘要： The challenge of making central requirements work at local levels is a common problem for environmental governance throughout the world. Countries can learn from one another s approaches, but must understand the local context in w
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EXPLORING THE RELATIVE ADVANTAGES OF LOCAL INNOVATION IN AGROFORESTRY

《农业科学与工程前沿（英文）》 2023年 第10卷 第1期   页码 61-72 doi: 10.15302/J-FASE-2022476

摘要：

● Promotion of local sustainable innovation developed by forest farmers.

关键词： agroforestry     forest farmers     local innovation     relative advantage     social forestry    

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高强钢筋混凝土预制弧板井壁力学特性分析

荣传新,王秀喜,程桦

《中国工程科学》 2005年 第7卷 第7期   页码 43-49

摘要：

对高强钢筋混凝土预制弧板井壁结构的研究表明，实验结果与数值计算结果基本一致。高强钢筋混凝土预制弧板井壁结构具有很高的承载能力，影响其承载能力的主要因素依次为混凝土的强度等级、厚径比和配筋率。在均布荷载作用下，混凝土的强度等级提高10MPa，极限承载力提高1.26MPa。厚径比每增加1%，极限承载力增加0.85 MPa。增大配筋率对提高其极限承载力作用不大，配筋率增大3倍，极限承载力只增加了0.1MPa。

关键词： 高强钢筋混凝土预制弧板井壁     力学特性     有限元法     ANSYS    

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Role of local governments in fostering the development of an emerging industry: A market-oriented policy

Jun JIN, Maureen McKELVEY, Ying DONG

《工程管理前沿（英文）》 2020年 第7卷 第3期   页码 447-458 doi: 10.1007/s42524-020-0104-6

摘要： This research investigates the role of local governments in stimulating an emerging industry and focuses on the specific growth of the new energy vehicle industry in Hangzhou, China. This research confirms that enabling firms to access emerging technology, acquire financial support, and touch customers and/or suppliers are critical to foster the emergence and development of industries. Moreover, the primary contribution of this study is to emphasize the support of the local government in the development of emerging industries on the perspective of the creation of a large-scale market demand. The creation of large-scale market demand may inspire actors to be proactive in responding to these incentives; thus, public and private actions may help increase the accessibility to technology, infrastructure, and finances. Hence, a market-oriented policy that incentivizes the creation and expansion of market demand among diverse public and private actors should be seen as the key issue for the emergence and growth of emerging industries. Policies should also be adopted promptly with the development of the market.

关键词： market demand     local government     new energy vehicles    

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Understand the local and regional contributions on air pollution from the view of human health impacts

《环境科学与工程前沿（英文）》 2021年 第15卷 第5期 doi: 10.1007/s11783-020-1382-2

摘要：

• PM2.5-related deaths were estimated to be 227 thousand in BTH & surrounding regions.

关键词： PM2.5     Regional transport     Local emissions     Health impact     Environmental inequality    

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ARC welding method for bonding steel with aluminum

Zhenyang LU, Pengfei HUANG, Wenning GAO, Yan LI, Hanpeng ZHANG, Shuyan YIN

《机械工程前沿（英文）》 2009年 第4卷 第2期   页码 134-146 doi: 10.1007/s11465-009-0033-x

摘要： When welding steel with aluminum, the appearance of intermetallic compounds of Fe and Al will decrease tenacity and increase rigidity, which leads to bad joint performance. A new type of low energy input (LEI) welding technology is introduced which can be used to weld steel with aluminum. Using the technology, brazing was located on the steel side and arc fusion welding on the aluminum side. The less heat input reduces the thickness of intermetallic compounds to 3-4 μm. Tensile strength tests prove that the joint breaks at the heat-affected zone and the strength is higher than 70% of the aluminum’s. Thus, the method can lead to a good performance joint.

关键词： joining of steel and aluminum     low energy input welding     arc welding     fusion welding – brazing    

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标题 作者 时间 类型 操作

Local arc discharge mechanism and requirements of power supply in micro-arc oxidation of magnesium alloy

Ming CHEN, Yuezhou MA, Yuan HAO,

期刊论文

Plasma-enabled healing of graphene nano-platelets layer

Xiuqi Fang, Carles Corbella, Denis B. Zolotukhin, Michael Keidar

期刊论文

Stress field near circular-arc interface crack tip based on electric saturation concept

Longchao DAI, Xinwei WANG

期刊论文

Development of a new wear resistant coating by arc spraying of a steel-based cored wire

Lidong ZHAO, Pia KUTSCHMANN, Binyou FU, Dingyong HE

期刊论文

Submerged arc plasma system combined with ozone oxidation for the treatment of wastewater containing

期刊论文

Experimental and modeling studies on installation of arc sprayed Zn anodes for protection of reinforced

Xianming SHI

期刊论文

Mathematical model and manufacture programming of loxodromic-type normal circular-arc spiral bevel gear

Zhenyun DUAN, Houjun CHEN, Zhilan JU, Jian LIU

期刊论文

High-order phase-field model with the local and second-order max-entropy approximants

Fatemeh AMIRI

期刊论文

Local uncorrelated local discriminant embedding for face recognition

Xiao-hu MA,Meng YANG,Zhao ZHANG

期刊论文

Making central-local relations work: Comparing America and China environmental governance systems

Dan GUTTMAN, SONG Yaqin

期刊论文

EXPLORING THE RELATIVE ADVANTAGES OF LOCAL INNOVATION IN AGROFORESTRY

期刊论文

高强钢筋混凝土预制弧板井壁力学特性分析

荣传新,王秀喜,程桦

期刊论文

Role of local governments in fostering the development of an emerging industry: A market-oriented policy

Jun JIN, Maureen McKELVEY, Ying DONG

期刊论文

Understand the local and regional contributions on air pollution from the view of human health impacts

期刊论文

ARC welding method for bonding steel with aluminum

Zhenyang LU, Pengfei HUANG, Wenning GAO, Yan LI, Hanpeng ZHANG, Shuyan YIN

期刊论文