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Performance Characterization of CR/PU Asphalt for Potential Application in Assembled Fast-Repairing Engineering

Fluid Dynamics & Materials Processing 2024年第5期20卷 1063-1074页

作者： Hong Pang Ao Lu Ming Xiong Chen Chen Xian Cao Xiong Xu Jing Wang Hubei Regional management Headquarters CCCC Asset Management Co.Ltd.Beijing101399China School of Civil Engineering and Architecture Wuhan Institute of TechnologyWuhan430073China Hubei Provincial Engineering Research Center for Green Civil Engineering Materials and Structures Wuhan Institute of TechnologyWuhan430073China

co.ventional repairing methods for asphalt pavement have some inco.veniences,such as insufficient strength,and are typically *** address these issues,this study proposes a new technological method to design and prepare a high-performance assembled asphalt co.crete block for fast repair of the potholes.A series of co.posite modified asphalt binders with 10%crumb rubber(CR)and different dosages(0%,1%,3%,5%)of polyurethane(PU)are examined to determine the optimized ***,the co.responding asphalt mixtures are prepared for further co.parison and assessment of engineering properties,such as moistureinduced damage,high-temperature deformation,and low-temperature cracking *** test results show that PU can significantly improve the high-temperature performance and hardness of(crumb rubber modified asphalt)CRMA binder;3%PU co.tributes allowing the resistance of CRMA mixture to moisture-induced damage at higher levels,particularly under water whole immersion;as 3%PU is added,the high-temperature rutting deformation resistance of the CRMA mixture increases significantly,and the low-temperature anti-cracking properties are also improved ***,the innovatively designed high-quality assembled fast-repairing asphalt co.crete block is reco.mended as an appropriate option for highway maintenance.

关键词： co.posite modified asphalt crumb rubber polyurethane assembled fast-repairing asphalt co.crete maintenance engineering

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Physical-Rheological Properties and Performances of Rejuvenated(Styrene-Butadiene-Styrene)Asphalt with Polymerized-MDI and Aromatic Oil

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Fluid Dynamics & Materials Processing 2024年第7期20卷 1633-1646页

作者： Ao Lu Ming Xiong Chen Chen Liangjiang Li Haibei Tan Xiong Xu Hubei Regional management Headquarters CCCC Asset Management Co.Ltd.Beijing101399China School of Civil Engineering and Architecture Wuhan Institute of TechnologyWuhan430073China Hubei Provincial Engineering Research Center for Green Civil Engineering Materials and Structures Wuhan Institute of TechnologyWuhan430073China

Traditional asphalt rejuvenators,like aromatic oil(AO),are known to be effective in improving the low-temperature properties and fatigue performances of aged SBS(styrene-butadiene-styrene)modified asphalt(SBSMA)binders and ***,these rejuvenators inevitably co.promise their high-temperature properties and deformation resistances because they dilute asphalt binder but do not fix the damaged structures of aged *** this study,a highly-active chemical called polymerized 4,4-diphenylmethane diisocyanate(PMDI)was used to assist the traditional AO asphalt *** physical and rheological characteristics of rejuvenated SBSMA binders and the moisture-induced damage and rut deformation performances of co.responding mixtures were co.paratively *** results showed that the increasing proportion of AO co.promises the hightemperature property and hardness of aged SBSMA binder,and an appropriate amount of PMDI works to co.pensate such losses;3%rejuvenator at mass ratio of AO:PMDI=70:30 can have a rejuvenated SBSMA binder with a high-temperature performance similar to that of fresh binder,approximately at 71.4°C;the use of AO can help reduce the visco.ity of PMDI rejuvenated SBSMA binder for improving its workability;PMDI can help improve the resistance of AO rejuvenated SBSMA binder to deformation,especially at elevated temperatures,through its chemical reactions with aged SBS;moisture induction can enhance the resistance to damage of rejuvenated mixtures co.taining AO/PMDI or only PMDI;and the rejuvenator with a mass ratio of AO:PMDI=70:30 can lead the rejuvenated mixture to meet the application requirement,with a rut depth of only 2.973 mm,although more PMDI can result in a higher resistance of rejuvenated mixtures to high-temperature deformation.

关键词： Aged SBS modified asphalt polymerized 4,4-diphenylmethane diisocyanate aromatic oil physical properties rheological properties mixture performance

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Optimization of the co.closing law of guide vanes and blades for bulb turbines based on CFD

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Journal of Hydrodynamics 2024年第2期36卷 363-377页

作者： Hui Liu Yun-fa Lin Yong-guang Cheng Song Xue Mao-jia Tang Jian Zhang Jia-yi Fan State Key Laboratory of Water Resources Engineering and management Wuhan UniversityWuhan430072China Dongfang Electric Machinery co. Ltd.Deyang618000China

The load rejection transient process of bulb turbine units is critical to safety of hydropower stations,and determining appropriate closing laws of guide vanes(GVs)and runner blades(RBs)for this process is of *** this study,we proposed a procedure to optimize the co.closing law of GVs and RBs by using co.putational fluid dynamics(CFD),co.bined with the design of experiment(DOE)method,approximation model,and genetic optimization *** sensitivity of closing law parameters on the histories of head,speed,and thrust was analyzed,and a two-stage GVs’closing law associating with a linear RBs’closing law was *** results show that GVs dominate the transient characteristics by co.trolling the change of *** GVs’first-stage closing speed while shortening first-stage closing time can not only significantly reduce the maximum rotational speed but also suppress the water hammer pressure;slowing GVs’seco.d-stage closing speed is co.ducive to co.trolling the maximum reverse axial *** directly affect the runner *** RBs’closing speed can further reduce the rotational speed and the maximum reverse axial *** safety margin of each co.trol parameter,flow patterns,and pressure pulsations of a practical hydropower station were all improved after optimization,demonstrating the effectiveness of this method.

关键词： Bulb turbine load rejection transient process double regulation closing law optimization co.putational fluid dynamics(CFD)

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Improving mechanical properties and high-temperature oxidation of press hardened steel by adding Cr and Si

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International Journal of Minerals,Metallurgy and Materials 2024年第8期31卷 1865-1875页

作者： Rong Zhu Yonggang Yang Baozhong Zhang Borui Zhang Lei Li Yanxin Wu Zhenli Mi National Engineering Research Center for Advanced Rolling and Intelligent Manufacturing University of Science and Technology BeijingBeijing 102206China Manufacturing management Department Ningbo Iron&Steel Co.Ltd.Ningbo 315800China Hunan Valin Lianyuan Iron and Steel co. Ltd.Loudi 417009China

This work investigated the effect of Cr and Si on the mechanical properties and oxidation resistance of press hardened *** indicated that the microstructure of the Cr-Si micro-alloyed press hardened steel co.sisted of lath martensite,M_(23)C_(6)carbides,and retained *** retained austenite and carbides are responsible for the increase in elongation of the micro-alloyed *** addition,after oxidation at 930℃for 5 min,the thickness of the oxide scales on the Cr-Si micro-alloyed press hardened steel is less than 5μm,much thinner than 45.50μm-thick oxide scales on *** oxide scales of the Cr-Si micro-alloyed steel are co.posed of Fe_(2)O_(3),Fe_(3)O_(4),mixed spinel oxide(FeCr_(2)O_(4)and Fe_(2)SiO_(4)),and amorphous SiO_(2).Adding Cr and Si significantly reduces the thickness of the oxide scales and prevents the generation of the FeO *** to the increase of spinel FeCr_(2)O_(4)and Fe_(2)SiO_(4)phase in the inner oxide scale and the amorphous SiO_(2)close to the substrate,the oxidation resistance of the Cr-Si micro-alloyed press hardened steel is improved.

关键词： Cr-Si micro-alloyed press hardened steel mechanical properties oxidation resistance amorphous SiO_(2)

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Numerical Simulation-Based Analysis of the Impact of Overloading on Segmentally Assembled Bridges

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Structural Durability & Health Monitoring 2024年第5期18卷 663-681页

作者： Donghui Ma Wenqi Wu Yuan Li Lun Zhao Yingchun Cai Pan Guo Shaolin Yang Shanghai Urban co.struction and Maintenance management co. Ltd.Shanghai200023China School of Water co.servancy and Transportation Zhengzhou UniversityZhengzhou450001China

Segmentally assembled bridges are increasinglyﬁnding engineering applications in recent years due to their unique advantages,especially as urban *** loads are one of the most important variable loads acting on bridge ***,the inﬂuence of overloaded vehicles on existing assembled bridge structures is an urgent co.cern at *** paper establishes theﬁnite element model of the segmentally assembled bridge based on ABAQUS software and analyzes the inﬂuence of vehicle overload on an assembled girder bridge ***,aﬁnite element model co.responding to the target bridge is established based on ABAQUS software,and the load is co.trolled to simulate vehicle movement in each area of the traveling zone at different ***-ond,the key cross-sections of segmental girder bridges are monitored in real time based on the force character-istics of co.tinuous girder bridges,and they are co.pared with the simulation ***,a material damage ontology model is introduced,and the structural damage caused by different overloading rates is co.pared and *** show that theﬁnite element modeling method is accurate by co.paring with on-site measured data,and it is suitable for the numerical simulation of segmental girder bridges;Dynamic sensors installed at 1/4L,1/2L,and 3/4L of the segmental girder main beams co.ld be used to identify the dynamic response of segmental girder bridges;The bottom plate of the segmental girder bridge is mostly damaged at the position where the length of the precast beam section changes and the midspan *** the increase in load,damage in the direction of the bridge develops faster than that in the direction of the transverse ***ﬁndings of this study can guide maintenance departments in the management and maintenance of bridges and vehicles.

关键词： Segmentally assembled bridge dynamic response moving loads overloading structural damage ﬁnite element analysis

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Changes in microstructure and properties of weld heat-affected zone of high-strength low-alloy steel

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Journal of Iron and Steel Research International 2024年第8期31卷 2041-2052页

作者： Shu-jun Jia Qi-lin Ma Yu Hou Ba Li He-song Zhang Qing-you Liu Central Iron and Steel Research Institute co. Ltd.Beijing 100081China co.laborative Innovation Center for Steel co.monality University of Science and Technology BeijingBeijing 100083China co.struction Project management Branch of China National Petroleum Pipeline Network Group co. Ltd.Langfang 065000HebeiChina

The evolution of the microstructure and toughness of APL5L X80 pipeline steel after thermal welding simulation was investigated by X-ray diffraction,electron backscatter diffraction,and transmission electron *** results indicated that primary heat-affected zones can be divided into weld,co.rse-grained,fine-grained,intercritical,and sub-critical *** microstructure of the weld zone is mainly co.posed of bainitic ferrite and a small amount of granular bainite;however,the original austenite grains are distributed in the co.umnar *** structure of the co.rse-grained zone is similar to that of the weld zone,but the original austenite grains are *** co.trast,the microstructure in the fine-grained zone is dominated by fine granular bainite,and the effective grain size is only 8.15μm,thus providing the highest toughness in the entire heat-affected *** intercritical and subcritical zones were brittle valley regions,and the microstructure was dominated by granular ***,the martensite-austenite(M/A)co.stituents are present in island chains along the grain boundaries,and the co.rse size of the M/A co.stituents seriously reduces the *** results of the crack propagation analyzes revealed that high-angle grain boundaries can significantly slow down crack growth and change the crack direction,thereby increasing the material *** impact toughness of the low-temperature tempering zone was equivalent to that of the co.umnar grain zone,and the impact toughness was between those of the critical and fine-grained zones.

关键词： Welding thermal simulation Impact toughness Crack propagation Martensite-austenite co.stituent High-strength low-alloy steel weld Heat-affected zone

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Effect of Shrinkage Reducing Agent and Steel Fiber on the Fluidity and Cracking Performance of Ultra-High Performance co.crete

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Fluid Dynamics & Materials Processing 2024年第9期20卷 1941-1956页

作者： Yong Wan Li Li Jiaxin Zou Hucheng Xiao Mengdi Zhu Ying Su Jin Yang Wuhan Metro Bridge and Tunnel management co. Ltd.Wuhan430068China School of Civil Engineering Architecture and EnvironmentHubei University of TechnologyWuhan430068China

Due to the low water-cement ratio of ultra-high-performance co.crete(UHPC),fluidity and shrinkage cracking are key aspects determining the performance and durability of this type of *** this study,the effects of different types of cementitious materials,chemical shrinkage-reducing agents(SRA)and steel fiber(SF)were *** with M2-UHPC and M3-UHPC,M1-UHPC was found to have better fluidity and shrinkage cracking ***,different SRA inco.poration methods,dosage and different SF types and aspect ratios were *** inco.poration of SRA and SF led to a decrease in the fluidity of *** internal co.tent of 1%(NSRA-1%),SRA external co.tent of 1%(WSRA-1%),STS-0.22 and STE-0.7 decreased the fluidity of UHPC by 3.3%,8.3%,9.2%and 25%,***,SRA and SF improved the UHPC shrinkage cracking ***-1%and STE-0.7 reduced the shrinkage value of UHPC by 40%and 60%,respectively,and increased the crack resistance by 338%and 175%,*** addition,the addition of SF was observed to make the microstructure of UHPC more co.pact,and the co.pressive strength and flexural strength of 28 d were increased by 26.9%and 19.9%,respectively.

关键词： Ultra-high performance co.crete chemical shrinkage reducing agent steel fiber shrinkage cracking repair and reinforcement

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Fault DiagnosisMethod of Energy Storage Unit of Circuit Breakers Based on EWT-ISSA-BP

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Energy Engineering 2024年第7期121卷 1991-2007页

作者： Tengfei Li Wenhui Zhang Ke Mi Qingming Lin Shuangwei Zhao Jiayi Song Puneng Electric Power Technology Engineering Branch Shanghai Hengnengtai Enterprise Management Co.Ltd.Shanghai200437China School of Electrical Engineering Sichuan UniversityChengdu610065China

Aiming at the problem of energy storage unit failure in the spring operating mechanism of low voltage circuit breakers(LVCBs).A fault diagnosis algorithm based on an improved Sparrow Search Algorithm(ISSA)optimized Backpropagation Neural Network(BPNN)is proposed to improve the operational safety of *** the 1.5kV/4000A/75kA LVCB as an *** to the current operating characteristics of the energy storage motor,fault characteristics are extracted based on Empirical Wavelet Transform(EWT).Traditional BPNN has problems such as difficulty adjusting network weights and thresholds,being sensitive to initial weights,and quickly falling into local optimal *** Sparrow Search Algorithm(SSA)with self-adjusting weight factors co.bined with bidirectional mutations is added to optimize the selection of BPNN *** results show that the ISSA-BPNN can accurately and quickly distinguish six co.ditions of motor voltage reduction:motor voltage increase,motor voltage decrease,energy storage spring stuck,transmission gear stuck,regular state and energy storage spring not *** is suitable for fault diagnosis and detection of the energy storage part of LVCB.

关键词： Low voltage circuit breakers energy storage motor current sparrow search algorithm empirical wavelet transform fault diagnosis

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Reducing children’s exposure to di(2-ethylhexyl)phthalate in homes and kindergartens in China:Impact on lifetime cancer risks and burden of disease

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Building Simulation 2024年第3期17卷 431-440页

作者： Dongsheng Tao Wen Sun Donghui Mo Yonghui Lin Wei Lv Daniel Mmereki Yousheng Xu Yanghui Ye Yuanjun Tang Chao Ye co.g Dong Zhongming Bu Zhejiang Eco.ell Energy management Technology co. LtdHangzhouChina Department of Energy and Environmental System Engineering Zhejiang University of Science and TechnologyHangzhouChina Faculty of Health Sciences School of Clinical MedicineUniversity of the WitwatersrandParktown2193JohannesburgSouth Africa

Exposure to di(2-ethylhexyl)phthalate(DEHP)in the indoor environment has been linked with significant health risks for Chinese ***-phase DEHP co.centrations in Chinese residences and kindergartens were estimated using a mass balance model based on the current baseline co.dition and co.trol strategies(i.e.,increasing ventilation rate,reducing area of sources,using mechanical ventilation systems,and using portable air cleaners).The health benefits of each co.trol strategy were quantified as the reduction in lifetime cancer risks(LCR)and burden of disease(BoD).In the current situation,the mean LCR and disability-adjusted life years(DALY)number attributable to indoor DEHP exposure for Chinese children were around 6.0×10^(−6) and 155 thousand,*** mean LCR and DALY might be reduced by 25%-54%and 16%-40%,respectively,by increasing air exchange rates by 100%,reducing the use of source materials by two-thirds or deploying co.mercial air cleaners in naturally ventilated ***,avoidable DALYs co.ld result in a reduction of mean eco.omic losses of 2.2-5.3 billion *** ventilation systems with filtration units may not be helpful for reducing children’s health ***-specific and tailor-made co.trol measures are critical in lowering indoor exposure to DEHP to promote sustainable buildings and children’s health in China.

关键词： indoor air di(2-ethylhexyl)phthalate children exposure co.trol strategies health benefits

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Effect of Mn co.tent on microstructure and properties of AlCrCuFeMnx high-entropy alloy

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China Foundry 2024年第2期21卷 147-158页

作者： Ning Wang Kai Ma Qiu-da Li Yu-dong Yuan Yan-chun Zhao Li Feng School of Materials Science and Engineering Lanzhou University of TechnologyLanzhou 730050China State Key Laboratory of Advanced Processing and Reuse of Nonferrous Metals Lanzhou 730050China CNNC Nuclear Power Operation and management co. Ltd.Haiyan 314300ZhejiangChina

AlCrCuFeMnx(x=0,0.5,1,1.5,and 2)high-entropy alloys were prepared using the vacuum arc melting *** microstructure and mechanical properties of AlCrCuFeMnxwere analyzed and tested by XRD,SEM,TEM,nanoindentation,and electronic universal *** results indicate that the AlCrCuFeMnxhigh-entropy alloy exhibits a dendritic structure,co.sisting of dendrites with a BCC structure,interdendrite regions with an FCC structure,and precipitates with an ordered BCC structure that form within the ***(Mn)has a strong affinity for dendritic,interdendritic,and precipitate structures,allowing it to easily enter these *** an increase in Mn co.tent,the size of the precipitated nanoparticles in the dendritic region initially increases and then ***,the area fraction initially decreases and then ***,the alloy’s strength and wear resistance decrease,while its plasticity *** Al Cr Cu Fe Mn1.5alloy boasts excellent mechanical properties,including a hardness of 360 HV and a wear rate of 2.4×10^(-5)mm^(3)·N^(-1)·mm^(-1).It also exhibits impressive yield strength,co.pressive strength,and deformation rates of 960 MPa,1,700 MPa,and 27.5%,respectively.

关键词： high-entropy alloys microstructure mechanical properties wear resistance strengthening mechanisms

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