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Journal of Materials Science & Technology 2019年第2期35卷 344-350页

作者： Jingjing Liang Yongsheng Liu Jinguo Li Yizhou Zhou Xiaofeng Sun Institute of Metal Research Chinese Academy of Sciences State Key Laboratory of Solidification Processing Northwestern Polytechnical University Space Manufacturing Technology (CAS Key Lab)

An overlay coating material was deposited on a single crystal superalloy SRR99 by laser *** microstructure and oxidation behavior of this coating was investigated through scanning electron microscopy(SEM) and X-ray diffraction(XRD). The results indicated that although the composition of the coating was chosen based on the γ' composition in René N5 superalloy, the primary solidification phase of this coating during laser cladding was γ-Ni. Furthermore, under the laser cladding condition, fine parallel dendrites grew epitaxially in the coating from the substrate, indicating the single crystal structure of the substrate was reproduced. When the single crystal MCrAlY coating was oxidized at 1000?, both Al_2O_3 and Al_2O_3 formed during initial oxidation process. As the oxidation time proceeded, the presence of Al_2O_3 facilitated the formation of NiAl_2O_4 spinel oxide. Once the spinel was observed, it flourished and induced some porosity in the scale. When the scale thickness increased to 6–7 μm, large area spallation of the scale began.

关键词： Laser cladding Single crystal growth Epitaxy overlay coating

Effect of anisotropic characteristics on the mechanical behavior of asphalt concrete overlay

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Frontiers of Structural and Civil Engineering 2019年第1期13卷 110-122页

作者： Lingyun YOU Zhanping YOU Kezhen YAN Department of Civil and Environmental Engineering Michigan Technological UniversityHoughtonMI 49931USA College of Civil Engineering Hunan UniversityChangsha 410082China

Asphalt concrete (AC)overlays placed over old asphalt pavement have become an alternative to repairing and reinforcing *** strength contributed by the AC overlay is strongly influenced by the anisotropic properties of the pavement *** study was conducted to analyze the influence of anisotropy,modulus gradient properties,and the condition of the AC overlay and old pavement contact plane on the mechanical behaviors of AC overlays,as well as to quantify the influence of the degree of anisotropy on the mechanical behaviors of AC overlay by a sensitivity analysis (SA).The mechanical behaviors of the AC overlay were numerically obtained using the three- dimensional finite element method with the aid of ABAQUS,a commercial *** in the AC overlay's modulus as a function of temperature as well as the contact state between the AC overlay and AC layer were considered. The SA is based on standardized regression coefficients *** the mechanical behavior in terms of surface deflection,stress,and strain of the anisotropy model against those corresponding to the isotropic model under static loads show that the anisotropic properties had greater effects on the mechanical behavior of the AC *** addition,the maximum shear stress in the AC overlay was the most significant output parameter affected by the degree of anisotropy. Therefore,future research concerning the reinforcement and repair of pavements should consider the anisotropic properties of the pavement materials.

关键词： asphalt concrete overlay anisotropy temperature gradients modulus gradients finite element simulation sensitivity analysis

Effects of existing concrete pavement condition on performance of unbonded jointed plain concrete overlay

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Journal of Traffic and Transportation Engineering(English Edition) 2019年第6期6卷 567-576页

作者： Gauhar Sabih Rafiqul A.Tarefder Department of Civil Engineering University of New MexicoAlbuquerqueNM 87131USA

Unbonded concrete overlay(UBCO) is the most used pavement rehabilitation technique across United States with an overall usage of 47% amongst all the rehabilitation *** is aimed to improve the performance of any deteriorated/cracked jointed plain concrete pavement(JPCP).Unbonded JPCP overlay involves placement of a separation layer of hot mix asphalt(HMA),which acts as a stress relief layer between the existing concrete pavement and the *** are numerous factors that affect the design and performance of UBCOs and out of these,existing pavement condition or the severity of damage of existing pavement is a prime *** severity of damage is described by the distressed elastic modulus thus,accurate determination of the distressed elastic modulus of the existing concrete pavement is essential for predicting the accurate performance of the unbonded *** study focuses on analyzing the impact of distressed modulus by conducting simulations in the AASHTOWare pavement ME design software version 2.3 and evaluating the predicted performance of JPCP overlay for two different climatic *** results indicated that the distressed modulus of existing concrete pavement affects the performance of the overlay with regards to transverse cracking,joint faulting and pavement *** cracking is the most affected performance parameter with a change of 0.27% 2.31% with a unit change in distressed *** impact of climatic conditions on the performance of unbonded overlay was also *** adverse effects of distressed modulus can be minimized by reducing the joint spacing or increasing the overlay slab thickness.

关键词： Unbonded concrete overlay Transverse cracking Joint faulting International roughness index Distressed Elastic modulus

Research on the process of fabricating a multi-layer metal micro-structure based on UV-LIGA overlay technology

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Nanotechnology and Precision Engineering 2019年第2期2卷 83-88页

作者： Yali Ma Wenkai Liu Chong Liu Department of Military Materials Distribution Army Military Transportation UniversityTianjin 300161China School of Mechanical Engineering Dalian University of TechnologyDalian 116023China

In this paper,we report the study of the process of fabricating a multi-layermetal micro-structure using UV-LIGA overlay technology,includingmask fabrication,substrate treatment,and UV-LIGA overlay *** solve the process problems in the masking procedure,the swelling problemof the first layer of SU-8 thick photoresist was studied *** 5μmline-width compensation and closed 20μmand 30μmisolation strips were designed and fabricated around the micro-structure *** pore problemin the Ni micro-electroforming layer was analyzed and the electroforming parameters were *** pH value of the electroforming solution should be controlled between 3.8 and 4.4 and the current density should be below 3 A/dm^*** solve the problems of high inner stress and incomplete development of the micro-cylinder hole array with a diameter of 30μm,the lithography process was *** pre-baking temperature was increased via gradient heating and rose every 5℃ from 65℃ to 85℃ and then remained at 85℃ for 50 min–1 *** addition,the full contact exposure was ***,a multi-layer metal micro-structure with high precision and good quality of microelectroforming layer was fabricated using UV-LIGA overlay technology.

关键词： UV-LIGA overlay technology SU-8 photoresist Micro-electroforming technology Multi-layer metal micro-structure

BulkTree: an overlay network architecture for live media streaming

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2006年第Z1期7卷 125-130页

作者： GONG An DING Gui-guang DAI Qiong-hai LIN Chuang Department of Computer Science & Technology Tsinghua University Beijing 100084 China Broadband Networks & Digital Media Laboratory Department of Automation Tsinghua University Beijing 100084 China Broadband Networks & Digital Media Laboratory Department of Automation Tsinghua University Beijing 100084 China Department of Computer Science & Technology Tsinghua University Beijing 100084 China

Peer-to-peer (P2P) systems are now very popular. Current P2P systems are broadly of two kinds, structured and unstructured. The tree structured P2P systems used technologies such as distributed hash tables (DHT) and hierarchical clustering can search the required target quickly, however, in a tree, the internal node has a higher load and its leave or crash often causes a large population of its offspring's problems, so that in the highly dynamic Internet environment the tree structure may still suffer frequent breaks. On the other hand, most widely used unstructured P2P networks rely on central directory servers or massive message flooding, clearly not scalable. So, we consider both of the above systems' advantages and disadvantages and realize that in the P2P systems one node may fail easily, but that when a number of nodes organized as a set, which we call "super node", the set is robust. Super nodes can be created and updated aware of topology-aware, and used with simple protocol such as flooding or "servers" to exchange information. Furthermore the entire robust super node can be organized into exquisite tree structure. By using this overlay network architecture, P2P systems are robust, efficient, scalable and secure. The simulation results demonstrated that our architecture greatly reduces the alteration time of the structure while decreasing the average delay time, compared to the common tree structure.

关键词： Peer-to-peer (P2P), overlay networks, Scalability, Live media, Distributed hash tables (DHT), Hierarchical clustering

Long-term performance of fiber-grid-reinforced asphalt overlay pavements: A case study of Korean national highways

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Journal of Traffic and Transportation Engineering(English Edition) 2019年第4期6卷 366-382页

作者： Jong-Hoon Lee Seung-Beom Baek Kang-Hoon Lee Jo-Soon Kim Jin-Hoon Jeong Department of Civil Engineering Inha UniversityIncheon 22212South Korea Civil&Environmental BG Doosan Engineering&ConstructionSeoul 06057South Korea Department of Infrastructure Safety Research Korea Institute of Civil Engineering and Building TechnologyGoyang-si 10223South Korea SN Construction Co. LtdDaejeon 34573South Korea

The objective of this study was to verify the effect of fiber grid reinforcement on the longterm performance of asphalt overlay pavements by performing field investigation, laboratory test, and finite element analysis. Crack, rutting, roughness, and other miscellaneous distresses of fiber-grid-reinforced overlay sections and ordinary overlay sections were compared. Pavement conditions of fiber grid overlay sections before and after the overlay were also compared. Cores were obtained from the fiber-grid-reinforced and ordinary sections to measure bonding shear strength between the intermediate and overlay *** energy, displacement after yield, and shear stiffness of the cores were also obtained by analyzing the test results. Finite element analysis was performed by using the test results to validate the effect of the fiber grid reinforcement on the long-term performance of asphalt overlay pavements. Rutting and fatigue cracking were predicted for three cases: 1) fiber grid was not used;2) glass fiber grid was used;and 3) carbon fiber grid was used. The cracking ratio of fiber-grid-reinforced sections was much smaller than that of ordinary sections. The results of field investigation, laboratory test, and finite element analysis showed that the fiber grid reinforcement improved the long-term performance of asphalt overlay pavements.

关键词： Asphalt pavement Fiber grid reinforcement overlay pavement Finite element analysis Bonding shear strength

A minimal-distance overlay for efficiently disseminating replicas in DHT-based P2P networks

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High Technology Letters 2011年第2期17卷 126-133页

作者：李文翔 Guo Chengcheng Wu Jing School of Electronics Information Wuhan University Wuhan 430079 P. R. China College of Information Science ＆ Engineering Wuhan University of Science ＆ Technology Wuhan 430081 P. R. China

In this paper, the problems of redundant traffic and redundant replicas tor efficient object replication in P2P overlay are studies. Firstly, a hierarchical and topology-aware P2P overlay is developed with κ-Medoids partition algorithm to achieve the minimal physical distance of all super peer pairs. Secondly, a new idea of placing at most one replica in a cluster of physically adjacent nodes is introduced to achieve scattered distribution of replicas. Lastly, an efficient replicas-query algorithm based on multiple hash functions is proposed. Theoretical analysis and simulation experiment on several performance metrics are given, and it is verified that the method in this paper can efficiently disseminate replicas across the network, increase query-hit ratio, and decrease redundant messages and storage spaces required.

关键词： peer-to-peer replication overlay redundancy Chord k-Medoids clustering

Benefiting from providing multi-dimensional view of peers in overlay of P2P streaming system

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High Technology Letters 2013年第2期19卷 214-220页

作者：苏杭 Wang Jinlin You Jiali Graduate University of Chinese Academy of Sciences National Network New Media Engineering Research Center Institute of AcousticsChinese Academy of Sciences

Most overlay of existing P2P streaming systems just focus on the view point of video content *** multi-dimensional overlay for the P2P streaming system(MDOPS) is proposed for providing multi-dimensional view including video data,peers' service capability and online stability based on locality sensitive *** organizes all Live/VoD peers and the above multi-dimensional information in a one-dimensinal DHT,uses range resource information publish/search and introduces multiple load balancing *** maintains an additional candidate coordinating peer list with high qualified peers who own the video data the peer would possibly access currently and in *** list could speed up the process of searching peers for data scheduling *** experiment based on trace of real streaming system has testified that MDOPS can effectively improve the quality of search results and smooth load distribution among peers without increasing the cost of resource publish/search.

关键词： Peer-to-Peer (P'2P) streaming overlay locality sensitive hashing rangesearch load balance

Nanoparticles-modified polymer-based solar-reflective coating as a cooling overlay for asphalt pavement

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International Journal of Smart and Nano Materials 2013年第2期4卷 102-111页

作者： He Wang Jing Zhong Decheng Feng Jing Meng Ning Xie School of Transportation Science and Engineering Harbin Institute of TechnologyHarbin 150001China School of Civil Engineering Harbin Institute of TechnologyHarbin 150001China

The phenomenon of rutting is one of the most serious problems on asphalt *** the surface temperature of the asphalt pavement is an effective method to solve the rutting problem on asphalt *** this study,a nano-sized-particlesfilled polymer composite was developed as an overlay to reflect solar energy and decrease the surface temperature of asphalt *** overlay was composed of acrylic or epoxy resin filled with nano TiO_(2) or nano TiNO_(2).The solar reflection of the nanoparticle-filled polymers was tested,and the results showed that solar reflection effectiveness of the TiO_(2)/acrylic composite reached the highest *** results of outdoor temperature tests indicate that the solar-reflective overlay could decrease the surface temperature of asphalt pavements by about 10℃ when the pavement temperature is about 60℃.

关键词： solar reflective nanoparticles polymer overlay asphalt pavement

A new type of wear resistant overlay welding rod

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中国有色金属学会会刊：英文版 2000年第3期10卷 372-374页

作者： ZHANG Qing hui(张清辉) Mechanical Engineering Institute, Xiangtan University, Xiangtan 411105, P.R.China 湘潭大学湖南湘潭

By adopting the alloy wire of Ni 80 Cr 20 as the welding core and adding the alloy elements of B, Si, Mo and W into the outer plating covering, a new type of wear resistant overlay welding rod of Ni Cr B Si was developed. This overlay welding rod has several properties such as low melting point and good fluidity. With low content of W and Mo, the wearability and crack resistance of the overlay welding rod can be increased, and the hardness can be increased to about HRC64. This kind of overlay rod has been applied to the overlay of wearable workpieces, such as the valves of high temperature, high pressure and the side plates of floor boarding brick die.

关键词： Ni Cr B Si wear resistant alloys overlay welding rod