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Investigation of internal phases of linear SBS modified bitumen at the nanoscale using AFM PF-QNM

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Journal of Traffic and Transportation Engineering(English Edition) 2023年第3期10卷 399-412页

作者： Chengwei Xing Liping Liu Wei Jiang Jinhuan Shan Jingjing Xiao Dongdong Yuan Wangjie Wu Key Laboratory of Special Area highway Engineering of Ministry of Education Chang'an UniversityXi'an 710064China school of highway Chang'an UniversityXi'an 710064China Key Laboratory of Road and Traffic Engineering of Ministry of Education Tongji UniversityShanghai 201804China school of Civil Engineering Chang'an UniversityXi'an 710064China

Currently,few studies explore the internal phases of styrene-butadiene-styrene(SBS)modified bitumen at the nanoscale,though the surface phases of SBS modified bitumen have been deeply understood through a lot of *** present study uses the atomic force microscopy(AFM)peak force quantitative nanomechanical mode(PF-QNM)to investigate the nanomechanical properties of the interior of linear SBS modified bitumen and corresponding mastics at the ***,the suitable experimental methods for the interior of bitumen and mastics are ***,the phase relationship between surfaces and interiors of linear SBS modified bitumen is determined by analyzing nanomechanical *** this basis,in comparison with the internal phases of base bitumen,the effect of modifiers on phases is deeply ***,the internal phases of linear SBS modified bituminous mastics are further *** results reveal that the interior of linear SBS modified bitumen only has two phases,which form in a manner like periphase and paraphase on the *** contrast to base bitumen,linear SBS modified bitumen does not create new phases and change the properties of original phases in the interior,but affects the proportion of A-phase and B-phase and presents the ***,due to the influence of preparation methods,only the bitumen area away from the fillers can be imaged by AFM *** can be found that the addition of mineral fillers also slightly changes the internal phase distribution of linear SBS modified bitumen,while the effect is less than that of fillers on base bitumen.

关键词： Road engineering SBS modified bitumen Internal phase AFM PF-QNM

Pavement structure and materials design for sea-crossing bridges and tunnel:Case study of the Hong Kong-Zhuhai-Macao Bridge

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Journal of Road Engineering 2022年第2期2卷 99-113页

作者： Aimin Sha Wei Jiang Jinhuan Shan Wangjie Wu Yupeng Li Shuangjiao Zhang Key Laboratory for Special Area highway Engineering of Ministry of Education Chang'an UniversityXi'an 710064China school of highway Chang'an UniversityXi'an 710064China

With the continuous development of bridge and tunnel construction technologies,large-scale sea-crossing bridges and tunnels have gradually become the preferred choice for regional *** construction technology of Hong Kong-Zhuhai-Macao Bridge(HZMB),one of the most representative sea-crossing passageways,is instructive for the construction of other large sea-crossing *** present,the pavement design method of sea-crossing passageways lacks pertinence as it still refers to specifications for design of common ***,it is necessary to consider the bridge and tunnel pavement of HZMB as a typical example to analyze key technical problems encountered in its design,construction and *** solutions for material selection and structural design built upon the analysis of such critical problems should thus follow *** on comprehensive literature research,it can be found that environmental variability,tunnel closure,structural differential settlement and expansion deformation are the key technical problems faced by pavement of sea-crossing *** view of the environmental variability,the steel deck-paving material and structure design of GMA-10 t SMA-13 is innovatively *** for the closure of immersed tube tunnel,warm-mix flame retardant asphalt mixture is used to control pavement design through key indexes such as temperature and limit oxygen *** the deformation of immersed pipe joints,BJ200 asphalt seamless expansion joint material is introduced,which effectively satisfies the multi-directional deformation between pipe joints and ensures the smoothness of the road surface and driving *** segmental joints,double-layer waterproof-coiled material is used to effectively prevent reflective cracks while ensuring the continuity of asphalt concrete ***,this paper provides a panel of ideas and methods for the pavement design of the same type of sea-crossing passageways.

关键词： Hong Kong-Zhuhai-Macao Bridge Steel deck paving Immersed tunnel pavement GMA Flame retardant and smoke suppression Seamless expansion joint

A new targeted on-ramp control approach considering both efficiency and equity

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Transportation Safety and Environment 2024年第3期6卷 85-95页

作者： Shengnan Li Minglun Li Jianjun Dai Pu Wang school of Traffic and Transportation Engineering Central South UniversityChangsha 410075HunanChina Hunan Communications Research Institute Co. LtdChangsha 410015HunanChina

On-ramp control is an effective approach for alleviating traffic congestion on ***,there is still a lack of on-ramp control approaches applicable to large regional highway ***,we develop a targeted on-ramp control approach applicable to regional highway networks by taking advantage of the vehicle source information,which pinpoints the on-ramps contributing major traffic flow to the highway ***,a combined and tunable controlling index is proposed to enhance the equity of the generated traffic control *** proposed on-ramp control approach is validated on an actual large highway network using actual travel demand *** indicate that the proposed approach can well mitigate the traffic congestion of highway bottleneck while at the same time enhancing the equity and practicability of the generated traffic control scheme.

关键词： on-ramp control vehicle source traffic congestion equity

Hysteresis of Dam Slope Safety Factor under Water Level Fluctuations Based on the LEM Coupled with FEM Method

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Computer Modeling in Engineering & Sciences 2022年第11期133卷 351-375页

作者： Guodong Liu Zhijun Zhou Shiqiang Xu Wenjing Mi school of highway Chang’an UniversityXi’an710046China College of Urban Rural Planning and Architectural EngineeringShangluo UniversityShangluo726000China

Water level variations have caused numerous dam slope collapse disasters around the world,illustrating the large influence of water level fluctuations on dam *** required indoor tests were conducted and a numerical model of an actual earth-filled dam was constructed to investigate the influences of the water level fluctuation rate and the hysteresis of the soil-water characteristic curve(SWCC)on the stability of the upstream dam *** results revealed that the free surface in the dam body for the desorption SWCC during water level fluctuations was higher than that for the adsorption SWCC,which would be more evident at higher water *** safety factor of the upstream dam slope initially decreased and then increased for the most dangerous water level as the water level rose and *** water level fluctuation rate mainly influenced the initial section of the safety factor variation curve,while the SWCC hysteresis mainly affected the minimum safety factor of the water level *** desorption SWCC is suggested for engineering ***,a quick prediction method is proposed to estimate the safety factor of upstream dam slopes with identical structures.

关键词： Water level SWCC safety factor dam slope hysteresis

Mechanical properties of rock bolt and analysis for the full-process of sliding failure based on rock mass absolute displacement

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Journal of Traffic and Transportation Engineering(English Edition) 2022年第3期9卷 490-506页

作者： Yanbin Luo Zhou Shi Chuanwu Wang Jianxun Chen Weiwei Liu Yao Li Yunfei Wu Key Laboratory for Bridge and Tunnel of Shaanxi Province Chang’an UniversityXi'an 710064China school of highway Chang’an UniversityXi'an 710064China

Previous studies rarely involved the mechanical properties of anchorage system under the condition of internal absolute displacement of surrounding rock and the solution of important parameters of anchorage system. In this paper, the absolute displacement law of rock mass under the anchorage system is analyzed by the fiber grating(FBG) multi-point displacement meter and multidirectional displacement conversion formula. Based on the coordinated deformation principle for rock bolt and rock mass, the mechanical analysis model for rock bolt-rock mass system is established, and the influence rules of rock bolt length, rock bolt diameter and rock bolt preload on the internal force distribution of rock bolt is studied based on the stress analysis of full-length rock bolt in a tunnel *** results show that:(1) with the increase of rock bolt length, the anchoring effect gradually enhances, but the improvement degree decreases gradually;(2) with the increase of rock bolt diameter, the anchoring effect is enhanced;at the same time, however, the shear stress of rock bolt is larger, and the possibility of rock bolt sliding also increases;and(3) with the increase of preload, the increase of “anchor length” makes the anti-sliding ability of rock bolt increase correspondingly, and the supporting effect of rock bolt increases gradually. Then the full-process analysis for the mechanical mechanism of rock bolt sliding failure and the iterative calculation method for rock bolt displacement are studied. At last, the numerical simulation for pull-out test is carried out through the finite element analysis to verify the calculation results of mechanical model, and according to the iterative operation, the two important parameters such as the interface shear stiffness K and the interface peak shear strength τPare solved. The analysis show that the numerical simulation results are in good agreement with the mechanical model calculation. This study can provide a theoretical basis

关键词： Tunnel engineering Absolute displacement Bolt-rock support system Sliding failure Neutral point

Large area van der Waals epitaxy of II-VI CdSe thin films for flexible optoelectronics and full-color imaging

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Nano Research 2022年第1期15卷 368-376页

作者： Wenwu Pan Junliang Liu Zekai Zhang Renjie Gu Alexandra Suvorova Sarah Gain Han Wang Ziyuan Li Lan Fu Lorenzo Faraone Wen Lei Department of Electrical Electronic and Computer EngineeringThe University of Western Australia35 Stirling HighwayCrawley 6009Australia Centre for Microscopy Characterisation and AnalysisThe University of Western Australia35 Stirling HighwayPerth 6009Australia Department of Electronic Materials Engineering Research School of PhysicsThe Australian National UniversityCanberra ACT 2601Australia

The demand for future semiconductor devices with enhanced performance and lower cost has driven the development of epitaxial growth of high quality,free-standing semiconductor thin film materials without the requirement of lattice matching to the substrate,as well as their transfer to other substrates and associated device processing *** work presents a study on the van der Waals epitaxy based molecular beam epitaxy of CdSe thin films on two-dimensional layered mica substrates,as well as related etch-free layer transfer technology of large area,free-standing layers and their application in flexible photodetectors for full-color *** photoconductor detectors based on these flexible CdSe thin films demonstrate excellent device performance at room temperature in terms of responsivity(0.2 A·W^(-1))and detectivity(1.5×10^(12)Jones),leading to excellent full-color imaging quality in the visible spectral *** etch-free and damage-free layer transfer method has been developed for transferring these CdSe thin films from mica to other substrate for further device processing and *** results demonstrate the feasibility of van der Waals epitaxy method for growing high quality,large area,and free-standing epitaxial layers without the requirement for lattice matching to substrate for applications in low-cost flexible and/or monolithic integrated optoelectronic devices.

关键词： CdSe flexible devices van der Waals epitaxy molecular beam epitaxy layer lift-off

Load-Aware VM Migration Using Hypergraph Based CDB-LSTM

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Intelligent Automation & Soft Computing 2023年第3期35卷 3279-3294页

作者： N.Venkata Subramanian V.S.Shankar Sriram school of Computing SASTRA Deemed-to-be UniversityThanjavur613401TamilnaduIndia Center for Information Super highway(CISH) School of ComputingSASTRA Deemed-to-be UniversityThanjavur613401TamilnaduIndia

Live Virtual Machine(VM)migration is one of the foremost techniques for progressing Cloud Data Centers’(CDC)proﬁciency as it leads to better resource *** workload of CDC is often dynamic in nature,it is better to envisage the upcoming workload for early detection of overload status,underload status and to trigger the migration at an appropriate point wherein enough number of resources are *** various statistical and machine learning approaches are widely applied for resource usage prediction,they often failed to handle the increase of non-linear CDC *** overcome this issue,a novel Hypergrah based Convolutional Deep Bi-Directional-Long Short Term Memory(CDB-LSTM)model is *** CDB-LSTM adopts Helly property of Hypergraph and Savitzky–Golay(SG)ﬁlter to select informative samples and exclude noisy inference&*** proposed approach optimizes resource usage prediction and reduces the number of migrations with minimal computa-tional complexity during live VM ***,the proposed prediction approach implements the correlation co-efﬁcient measure to select the appropriate destination server for VM migration.A Hypergraph based CDB-LSTM was vali-dated using Google cluster dataset and compared with state-of-the-art approaches in terms of various evaluation metrics.

关键词： Convolutional deep Bi-LSTM hypergraph live VM migration load aware migration cloud data centers VM consolidation

Evaluation methods and indexes of morphological characteristics of coarse aggregates for road materials:A comprehensive review

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Journal of Traffic and Transportation Engineering(English Edition) 2019年第3期6卷 256-272页

作者： Saisai Zhang Rui Li Jianzhong Pei school of highway Chang’an University

The morphological characteristics of coarse aggregates, namely shape profile, angularity and surface texture, have a significant effect on the mechanical properties of asphalt mixtures. The identification methods and evaluation indexes of the morphological characteristics are crucial for the coarse aggregates. First, the visual identification technologies, including charged coupled device (CCD) image processing, X-ray tomography imaging and laser scanning technology, are summarized in term of the characteristics, research status and existing problems. Based on the deficiencies of visual identification technologies, it is proposed to improve the three-dimensional reconstruction of aggregate particles by increasing the number of two-dimensional projection directions or scanning sections. Moreover, the evaluation indexes of coarse aggregate morphology were summarized from the three aspects, namely shape profile, angularity and surface texture. It is found that evaluation of the indexes based on two-dimensional profile images or unrelated to pavement performance could not adequately evaluate the morphological characteristics of coarse aggregates. Therefore, the evaluation methods and indexes of coarse aggregate morphological characteristics have been recommended based on the performance of asphalt mixtures in this paper, which is helpful to establish a complete set of an evaluation system for coarse aggregate morphology.

关键词： Road material Coarse aggregate Morphological characteristic Identification method Evaluation index

Research status and prospect of wind-vehicle-bridge coupling vibration system

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Journal of Traffic and Transportation Engineering(English Edition) 2022年第3期9卷 319-338页

作者： Wanshui Han Xiaodong Liu Xuelian Guo Shizhi Chen Gan Yang Huanju Liu school of highway Chang'an UniversityXian 710064China Department of Civil and Environment Engineering University of CaliforniaLos AngelesCA 90015USA school of Civil Engineering Hebei University of EngineeringHandan 056038China

To promote and develop the theoretical basis and application of the wind-vehicle-bridge coupling vibration system,the corresponding research status and prospects are reviewed and discussed from five aspects,i.e.,the analytical framework,the aerodynamic interference,the evaluation criteria,the design loads of long-span bridge and the double-deck railcum-road *** refining process of analysis system is reviewed from the aspects of simulation wind load,vehicle load and bridge structure,and the corresponding coupling *** aerodynamic interference,the development process is summarized from the simulative precision of the elements(wind,vehicle and bridge),the load cases and the object of *** evaluation criteria,the corresponding development course is summarized from the certain evaluation method to uncertain *** long-span bridge design load,the wind and vehicle loads are reviewed and summarized from current multinational codes and theoretical *** double-deck rail-cum-road bridge,the mechanism of multi-element coupling relationship and corresponding aerodynamic interference are both *** comprehensive review and summary,the analytical framework is in the process from simplification to *** simulation and consideration of the objects of structural interference gradually become *** corresponding simulation theory,wind tunnel scale,test equipment and technology are the key factors to limit its *** systematic evaluation of vehicle and bridge,the structural and systemic security are the basis of the evaluation,and the auxiliary components and functional evaluation need to be paid more *** evaluation criterion will be developed from certain method to reliability *** design load of long-span bridge,the vehicle load is gradually transferred from the simple application of the design load of small-medium span bridge into a complex model considering the load *** doubl

关键词： Bridge engineering Wind-vehicle-bridge coupling vibration Aerodynamic interference Double-deck rail-cum-road bridge Design loads of long-span bridges Evaluation rule