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Detection of internal crack growth in polyethylene pipe using guided wave ultrasonic testing

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Earthquake Engineering and Engineering Vibration 2024年第2期23卷 319-329页

作者： Jay Kumar Shah Hao Wang Said El-Hawwat Centre of Advanced Infrastructure and Transportation RutgersThe State University of New JerseyNJ 08854USA department of civil and environmental Engineering RutgersThe State University of New JerseyNJ 08854USA

Despite the success of guided wave ultrasonic inspection for internal defect detection in steel pipes,its application on polyethylene(PE)pipe remains relatively *** growth of internal cracks in PE pipe severely affects its pressure-holding capacity,hence the early detection of internal cracks is crucial for effective pipeline maintenance *** study extends the scope of guided wave-based ultrasonic testing to detect the growth of internal cracks in a natural gas distribution PE *** experiments and a finite element model were planned to study the wave-crack interaction at different stages of axially oriented internal crack growth with a piezoceramic transducer-based setup arranged in a pitch-catch *** dispersion analysis supplemented with preliminary experiments was performed to isolate the optimal inspection frequency,leading to the selection of the T(0,1)mode at 50-kHz for the investigation.A transmission index based on the energy of the T(0,1)mode was developed to trace the extent of simulated crack *** findings revealed an inverse linear correlation between the transmission index and the crack depth for crack growth beyond 20%crack depth.

关键词： polyethylene pipes internal cracks guided wave ultrasonic testing torsional modes finite element modeling

Seismic response of deep circular tunnels subjected to S-waves:Axial bending

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Underground Space 2024年第4期17卷 267-279页

作者： Chatuphat Savigamin Antonio Bobet Osvaldo P.M.Vitali HR Engineering Services Inc.MedleyFL 33166United States Lyles School of civil Engineering Purdue UniversityWest LafayetteIN 47907United States department of civil Environmentaland Construction EngineeringUniversity of Hawaii at ManoaHonoluluHI 96822United States

Ovaling deformation of circular tunnels has received great interest from the tunneling community because this mode of seismicinduced deformation is considered the most ***,there is growing evidence that other deformation modes can also be important and thus need to be considered in *** study presents a new analytical solution to estimate axial bending(snaking),a mode of deformation caused by S-waves impinging on a tunnel parallel to the tunnel *** solution is developed using the soilstructure interaction approach with the assumption that the interface between the ground and the tunnel lining is frictionless(fullslip).Full dynamic numerical simulations are conducted to verify the new full-slip solution,together with the existing no-slip *** of dynamic amplification are also explored for both full-slip and no-slip interface conditions by changing the wavelength(or frequency)of the seismic input motions.

关键词： Seismic response of tunnels Analytical solutions Soil-structure interaction Axial bending Snaking S-waves

Preface:Heavy metal(loid)s at mining&metallurgical sites:Fate,risk and remediation

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Journal of Central South University 2024年第4期31卷 1033-1035页

作者：薛生国李楚璇赵东叶吴川 School of Metallurgy and Environment Central South UniversityChangsha 410083China department of civil Constructionand Environmental EngineeringSan Diego State UniversitySan DiegoCA 92182USA

The contamination of heavy metal(loid)s at mining&metallurgical sites has been a major environmental challenge worldwide[1].Typically,large amounts of metal(loid)s-bearing wastes are generated at these sites,such as smelting slag,combustion residues,mine tailings,wastewater,and exhaust gas[2].Due to their high mobility in the environment,the released heavy metal(loid)s can easily enter the soil and water environment,posing long-term and widespread threats to ecological and human health[3].

关键词： mining wastewater smelting

Continuous flow pyrolysis of virgin and waste polyolefins:a comparative study,process optimization and product characterization

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Frontiers of Chemical Science and Engineering 2024年第6期18卷 133-149页

作者： Ecrin Ekici Güray Yildiz Magdalena Joka Yildiz Monika Kalinowska ErolŞeker Jiawei Wang Karlsruhe Institute of Technology Institute of Catalysis Research and TechnologyEggenstein-Leopoldshafen 76344Germany Izmir Institute of Technology Faculty of EngineeringDepartment of Energy Systems EngineeringIzmir 35430Türkiye department of Materials Engineering and Production Faculty of Mechanical EngineeringBialystok University of TechnologyBialystok 15-351Poland department of Agricultural and Food Engineering and environmental Development Institute of Civil Engineering and EnergeticsFaculty of Civil Engineering and Environmental SciencesBialystok University of Technology15-351 BialystokPoland department of Chemistry Biology and BiotechnologyInstitute of Civil Engineering and EnergeticsFaculty of Civil Engineering and Environmental SciencesBialystok University of TechnologyBialystok 15-351Poland Izmir Institute of Technology Faculty of EngineeringDepartment of Chemical EngineeringIzmir 35430Türkiye Energy and Bioproducts Research Institute(EBRI) Aston UniversityBirmingham B47ETUnited Kingdom

Under optimal process conditions,pyrolysis of polyolefins can yield ca.90 wt%of liquid product,i.e.,combination of light oil fraction and heavier *** this work,the experimental findings reported in a selected group of publications concerning the non-catalytic pyrolysis of polyolefins were collected,reviewed,and compared with the ones obtained in a continuously operated bench-scale pyrolysis *** process parameters were used for the pyrolysis of waste and virgin counterparts of high-density polyethylene,low-density polyethylene,polypropylene and a defined mixture of those(i.e.,25:25:50 wt%,respectively).To mitigate temperature drops and enhance heat transfer,an increased feed intake is employed to create a hot melt plastic *** 1.5 g·min^(-1) feed intake,1.1 L·min^(-1) nitrogen flow rate,and a moderate pyrolysis temperature of 450℃,the formation of light hydrocarbons was favored,while wax formation was limited for polypropylene-rich *** of virgin plastics yielded more liquid(maximum 73.3 wt%)than that of waste plastics(maximum 66 wt%).Blending polyethylenes with polypropylene favored the production of liquids and increased the formation of gasoline-range *** products were mainly composed of C3 hydrocarbons,and no hydrogen production was detected due to moderate pyrolysis temperature.

关键词： waste plastics polyolefins chemical recycling pyrolysis alternative fuels waste-to-energy

Effects of freeze-thaw cycles on sandstone in sunny and shady slopes

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第7期16卷 2503-2515页

作者： Dian Xiao Xiaoyan Zhao Corrado Fidelibus Roberto Tomás Qiu Lu Hongwei Liu Academy of Railway Sciences Corporation Limited BeijingChina Faculty of Geosciences and environmental Engineering Southwest Jiaotong UniversityChengduChina department of civil Engineering University of AlicanteAlicanteSpain department of Innovation Engineering University of SalentoLecceItaly department of Earth and environmental Sciences University of Milano BicoccaMilanItaly

A growing rock engineering activity in cold regions is facing the threat of freeze-thaw(FT)weathering,especially in high mountains where the sunny-shady slope effects strongly control the difference in weathering behavior of *** this paper,an investigation of the degradation of petrophysical characteristics of sandstone specimens subjected to FT cycle tests to simulate the sunny-shady slope effects is *** this aim,non-destructive and repeatable testing techniques including weight,ultrasonic waves,and nuclear magnetic resonance methods on standard specimens were *** the sunny slope specimens,accompanied by the enlargement of small pores,100 FT cycles caused a significant decrease in P-wave velocity with an average of 23%,but a consistent rise of 0.18%in mass loss,34%in porosity,67%in pore geometrical mean radius,and a remarkable 14.5-fold increase in ***,slight changes with some abnormal trends in physical parameters of the shady slope specimens were observed during FT cycling,which can be attributed to superficial granular disaggregation and pore throat *** shocks enhance rock weathering on sunny slopes during FT cycles,while FT weathering on shady slopes is restricted to the small pores and the superficial *** two factors are primarily responsible for the differences in FT weathering intensity between sunny and shady *** conclusions derived from the interpretation of the experimental results may provide theoretical guidance for the design of slope-failure prevention measures and the selection of transportation routes in cold mountainous regions.

关键词： Sunny-shady slope Freeze and thaw Pore structure Tight rocks Talus slope Cold regions

Monitoring and evaluation of the water quality of the Lower Neches River, Texas, USA

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Water Science and Engineering 2024年第1期17卷 21-32页

作者： Qin Qian Mengjie He Frank Sun Xinyu Liu department of civil and environmental Engineering Lamar UniversityBeaumontTX 77710USA department of Industry Engineering Lamar UniversityBeaumontTX 77710USA department of Computer Science Lamar UniversityBeaumontTX 77710USA

Increasing bacteria levels in the Lower Neches River caused by Hurricane Harvey has been of a serious *** study is to analyze the historical water sampling measurements and real-time water quality data collected with wireless sensors to monitor and evaluate water quality under different hydrological and hydraulic *** statistical and Pearson correlation analysis on historical water samples determines that alkalinity,chloride,hardness,conductivity,and pH are highly correlated,and they decrease with increasing flow rate due to *** flow rate has positive correlations with Escherichia coli,total suspended solids,and turbidity,which demonstrates that runoff is one of the causes of the elevated bacteria and sediment loadings in the *** correlation between *** and turbidity indicates that turbidity greater than 45 nephelometric turbidity units in the Neches River can serve as a proxy for *** to indicate the bacterial outbreak.A series of statistical tools and an innovative two-layer data smoothing filter are developed to detect outliers,fill missing values,and filter spikes of the sensor *** correlation analysis on the sensor data illustrates that the elevated sediment/bacteria/algae in the river is either caused by the first flush rain and heavy rain events in December to March or practices of land use and land ***,utilizing sensor measurements along with rainfall and discharge data is recommended to monitor and evaluate water quality,then in turn to provide early alerts on water resources management decisions.

关键词： Water quality Pearson correlation analysis Lower Neches River YSI wireless sensors Non-point pollution

Hydroxyl radical production by abiotic oxidation of pyrite under estuarine conditions:The effects of aging,seawater anions and illumination

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Journal of environmental Sciences 2024年第1期135卷 715-727页

作者： Ruixue Liu Yinshun Dai Yucheng Feng Shiwen Sun Xiaodong Zhang Chunjiang An Shan Zhao Shandong Key Laboratory of Water Pollution Control and Resource Reuse School of Environmental Science and EngineeringShandong UniversityQingdao 266237China department of Building Civil and Environmental EngineeringConcordia UniversityMontrealQC H3G 1M8Canada

Pyrite is widely distributed in estuarine sediments as an inexpensive natural Fenton-like reagent,however,the mechanism on the hydroxyl radical(HO^(·))production by pyrite under estuarine environmental conditions is still poorly *** batch experiments were performed to investigate the effects of estuarine conditions including aging(in air,in water),seawater anions(Cl^(-),Br^(-)and HCO_(3)^(-))and light on the HO^(·)production by pyrite *** one-electron transfer dominated the process from O_(2) to HO^(·)induced by oxidation of *** Fe(oxyhydr)oxide coatings on the surface of pyrite aged in air and water consumed hydrogen peroxide while mediating the electron transfer,and the combined effect of the two resulted in a suppression of HO^(·)production in the early stage of aging and a promotion of HO^(·)production in the later stage of *** of the surface oxide layers by aggressive anions was the main reason for the inhibition of HO^(·)production by Cl^(-)and Br^(-),and the generation of Cl^(·)and Br^(·)may also play a role in the scavenging of HO^(·).HCO_(3)^(-)increased the average rate of HO^(·)production through surface-CO_(2) complexes formed by adsorption on the surface of *** significant enhancement of HO^(·)production under light was attributed to the formation of photoelectrons induced by photochemical reactions on pyrite and its surface oxide *** findings provide new insights into the environmental chemical behavior of pyrite in the estuary and enrich the understanding of natural remediation of estuarine environments.

关键词： Hydroxyl radical Pyrite oxidation Aging Anions Irradiation

A stable implicit nodal integration-based particle finite element method(N-PFEM)for modelling saturated soil dynamics

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第6期16卷 2172-2183页

作者： Liang Wang Xue Zhang Jingjing Meng Qinghua Lei department of Earth Sciences ETH ZürichZürich8092Switzerland department of civil Engineering and Industrial Design University of LiverpoolLiverpoolL693BXUK department of civil Environmental and Natural Resources EngineeringLuleåUniversity of TechnologyLuleå97187Sweden department of Earth Sciences Uppsala UniversityUppsala75105Sweden

In this study,we present a novel nodal integration-based particle finite element method(N-PFEM)designed for the dynamic analysis of saturated *** approach incorporates the nodal integration technique into a generalised Hellinger-Reissner(HR)variational principle,creating an implicit PFEM *** mitigate the volumetric locking issue in low-order elements,we employ a node-based strain smoothing *** discretising field variables at the centre of smoothing cells,we achieve nodal integration over cells,eliminating the need for sophisticated mapping operations after re-meshing in the *** express the discretised governing equations as a min-max optimisation problem,which is further reformulated as a standard second-order cone programming(SOCP)***,pore water pressure,and displacements are simultaneously determined using the advanced primal-dual interior point ***,our numerical model offers improved accuracy for stresses and pore water pressure compared to the displacement-based PFEM *** experiments demonstrate that the N-PFEM efficiently captures both transient and long-term hydro-mechanical behaviour of saturated soils with high accuracy,obviating the need for stabilisation or regularisation techniques commonly employed in other nodal integration-based PFEM *** work holds significant implications for the development of robust and accurate numerical tools for studying saturated soil dynamics.

关键词： Particle finite element method Nodal integration Dynamic saturated media Second-order cone programming(SOCP)

Collaborative multi-lane on-ramp merging strategy for connected and automated vehicles using dynamic conflict graph

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Journal of Intelligent and Connected Vehicles

Journal of Intelligent and Connected Vehicles 2024年第1期7卷 38-51页

作者： Jia Shi Yugong Luo Pengfei Li Jiawei Wang Keqiang Li School of Vehicle and Mobility Tsinghua UniversityBeijing 100084China department of civil and environmental Engineering University of MichiganAnn ArborMI 48109USA

The on-ramp merging in multi-lane highway scenarios presents challenges due to the complexity of coordinating vehicles’merging and lane-changing behaviors,while ensuring safety and optimizing traffic ***,there are few studies that have addressed the merging problem of ramp vehicles and the cooperative lane-change problem of mainline vehicles within a unified framework and proposed corresponding optimization *** tackle this issue,this study adopts a cyber-physical integration perspective and proposes a graph-based solution ***,the information of vehicle groups in the physical plane is mapped to the cyber plane,and a dynamic conflict graph is introduced in the cyber space to describe the conflict relationships among vehicle ***,graph decomposition and search strategies are employed to obtain the optimal solution,including the set of mainline vehicles changing lanes,passing sequences for each route,and corresponding ***,the proposed dynamic conflict graph-based algorithm is validated through simulations in continuous traffic with various densities,and its performance is compared with the default algorithm in *** results demonstrate the effectiveness of the proposed approach in improving vehicle safety and traffic efficiency,particularly in high traffic density scenarios,providing valuable insights for future research in multi-lane merging strategies.

关键词： cooperative merging multi-lane graph theory cyber-physical integration system