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Evaluation of pavement skid resistance using high speed texture measurement

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Journal of Traffic and Transportation Engineering(English Edition) 2015年第6期2卷 382-390页

作者： jay n.meegoda Shengyan Gao Department of Civil & Environmental Engineering New Jersey Institute of Technology

Skid resistance is an important parameter for highway designs, construction, management, maintenance and safety. The purpose of this manuscript is to propose the correlation between skid resistance, which is measured as skid resistance trailer, and mean profile depth （MPD） or the macro surface texture, which is measured by vehicle mounted laser, so that highway agencies can predict the skid resistance of pavement without the use of expensive and time consuming skid resistance trailer, which also causes disruption of traffic in use. In this research skid numbers and MPD from 5 new asphalt pavements and 4 old asphalt pavements were collected using a locked wheel skid trailer and a vehicle mounted laser. Using the data collected, a correlation between the skid number （Sn40R） collected by locked wheel skid tester and the texture data or MPD collected by a vehicle mounted laser operating at highway speeds was developed. The proposed correlation for new pavements was positive for MPD values less than 0.75 mm to reach a peak Sn40R value, then there was a negative correlation as the MPD increases until the MPD value was equal to 1.1 mm and beyond the MPD value of 1.1 mm to the maximum value of 1.4 mm, Sn40R value remained almost constant. There were significant data scatter for the MPD value of 0.8 mm. To explain these results, water film thickness during the friction test was calculated and the critical MPD was defined. The effect of sealed water pool on the Sn40R was discussed. The test result showed a similar trend for older asphalt pavements, but with lower Sn40R values due to the polishing of pavement micro-texture by traffic. Hence, a reduction factor was proposed for older pavements based on cumulative traffic volume for the above correlation to predict the skid resistance of older pavements.

关键词： Skid resistance High speed laser Pavement texture Cumulative traffic volume Locked wheel skid trailer Mean profile depth

Characterization of meso-scale mechanical properties of Longmaxi shale using grid microindentation experiments

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Journal of Rock Mechanics and Geotechnical Engineering 2021年第3期13卷 555-567页

作者： Jianting Du Andrew J.Whittle Liming Hu Thibaut Divoux jay n.meegoda State Key Laboratory of Hydro-Science and Engineering Tsinghua UniversityBeijing100084China Department of Civil and Environmental Engineering Massachusetts Institute of TechnologyCambridgeMA02139USA MultiScale Material Science for Energy and Environment UMI 3466CNRS-MITCambridgeMA02139USA Univ Lyon Ens de LyonUniv Claude BernardCNRSLaboratoire de PhysiqueLyonF-69342France Department of Civil and Environmental Engineering New Jersey Institute of TechnologyNewarkNJ07102USA

Mechanical properties,such as the hardness H,Young’s modulus E,creep modulus C,and fracture toughness Kc,are essential parameters in the design of hydraulic fracturing systems for prospective shale gas *** this study,a practical methodology is presented for obtaining these properties through microindentation experiments combined with quantitative observations of the mineralogical phases using X-ray diffraction(XRD),scanning electron microscopy(SEM)with backscattered electron(BSE)imaging,and energy-dispersive X-ray spectroscopy(EDS)*** apply this method in the case of three types of Longmaxi shales with different mineralogies(***-,clay-,and quartz-rich,respectively),which allows us to determine the characteristic indentation depth,hc?8e10 mm,beyond which the mechanical response of the carbonate-rich shale is homogeneous and independent of its complex heterogeneous ***,exploiting the results of a large number of indentation tests,we demonstrate that the indentation modulus M of the shale increases as a power-law of hardness H,and its creep modulus C increases linearly with *** also compute the fracture toughness Kc from the indentation data by assuming a perfectly plastic behavior of the *** results are in good agreement with independent measurements of Kc determined by microscratch ***,further tests on quartz-and clay-rich samples of the Longmaxi shale suggest further variations in the samples’mechanical properties depending on their burial conditions and the mechanical properties of their dominant mineral phases.

关键词： Grid microindentation Mineral identification Hardness Modulus Creep Fracture toughness

Fleet size estimation for spreading operation considering road geometry,weather and traffic

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Journal of Traffic and Transportation Engineering(English Edition) 2014年第1期1卷 1-12页

作者： Steven I-Jy Chien Shengyan Gao jay n.meegoda Taha F.Marhaba Department of Civil & Environmental Engineering New Jersey Institute of Technology School of Automobile Chang'an University

Extreme weather conditions（i, e. snow storm） in winter time have caused significant travel disruptions and increased delay and traffic accidents. Snow plowing and salt spreading are the most common counter-measures for making our roads safer for motorists. To assist highway maintenance authorities with better planning and allocation of winter maintenance re- sources, this study introduces an analytical model to estimate the required number of trucks for spreading operation subjective to pre-specified service time constraints considering road geome- try, weather and traffic. The complexity of the research problem lies in dealing with heteroge- neous road geometry of road sections, truck capacities, spreading patterns, and traffic speeds under different weather conditions and time periods of an event. The proposed model is applied to two maintenance yards with seven road sections in new Jersey （USA）, which demonstrates itself fairly practical to be implemented, considering diverse operational conditions.

关键词： fleet size road geometry road network spreading operation traffic speed winter road maintenance

Sustainable Toilet for a Developing nation

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Sustainable Toilet for a Developing Nation

numerical analysis and centrifugal modeling of LnAPLs transport in subsurface system

2011 International Conference on Future Management Science and Engineering(ICFMSE 2011)

作者： jay n.meegoda H.n.Hsieh P.Rodriguez J.Jawidzik Civil & Environmental Engineering NJIT Mechanical Engineering NJIT

The new Jersey Institute of Technology working with the Center for the Rural Development of Milot（CRUDEM） in Milot,Haiti has developed an ecologically sustainable sanitation system for the local hospital H?pital Sacré *** will collect human waste,convert it into fertilizer through anaerobic digestion,and capture the methane gas emissions,which are a byproduct of the process for on-site use as a heating *** liquid and solid separation of human waste is done to prevent counter-productive saturation of the solid waste.A solid waste holding container was designed to allow anaerobic decomposition and for continuous fertilizer production and methane harvesting.

关键词： Pathogen Agriculture Fertilizer Methane Capture Developing Country Sustainable Development Human waste anaerobic digestion

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Progress in natural Science:Materials International 2006年第4期16卷 416-424页

作者： LO I.M.C. meegoda J.n. Department of Civil Engineering Hong Kong University of Science and Technology Hong Kong SARChina Department of Civil and Environmental Engineering new Jersey Institute of Technology USA

The transport of non-aqueous phase liquids (nAPLs) in unsaturated soils and groundwater is an important research topic in geo-environmental engineering. In this paper, the mechanism of light nAPLs (LnAPLs) transport in subsurface system is briefly introduced, and the mass transport equations, fluid flow equations, and the constitutive model of relative permeability - saturation - capillary pressure are discussed. Then the numerical method is introduced to simulate the multiphase flow problems in porous media, and the tempospatial distribution of LnAPLs is obtained. Moreover, different boundary conditions are employed in numerical simulation to investigate its effect on transport behavior. To verify the numerical data, centrifugal tests are conducted to model the LnAPLs migration in unsaturated soils and groundwater. The calculation results are agreeable with the experimental findings of centrifugal modeling, which indicates that LnAPLs from leaking point move downwards due to gravity force, and form a high concentration zone above the capillary fringe, and then spread out laterally along the groundwater table. Some LnAPL enters groundwater system to further migrate. The combination of numerical simulation and centrifuge modeling can be a useful means to study the transport behavior of LnAPLs in subsurface system.

关键词： geo-environmental engineering subsurface contamination multiphase flow light non-aqueous phase liquids (LnAPLs) centrifugal modeling technique numerical simulation.

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基于岩土介质三维孔隙结构的两相流模型

岩土工程学报 2020年第1期42卷 37-45页

作者：张鹏伟胡黎明 jay n.meegoda Michael A Celia 清华大学水沙科学与水利水电工程国家重点实验室北京100084 北京交通大学北京100044 新泽西理工学院美国07102 普林斯顿大学美国08544

地下储层中岩土介质一般具有较低的孔隙连通性,宏观流动模拟一般忽略微观尺度的孔隙连通性,通过渗透率、弯曲度等参数反映储层的整体特性。但岩土介质的多孔性及孔隙间复杂的连通性,使得宏观描述流体在岩土介质中流动不能反映其内在流... 详细信息

地下储层中岩土介质一般具有较低的孔隙连通性,宏观流动模拟一般忽略微观尺度的孔隙连通性,通过渗透率、弯曲度等参数反映储层的整体特性。但岩土介质的多孔性及孔隙间复杂的连通性,使得宏观描述流体在岩土介质中流动不能反映其内在流动特征。孔隙结构模型的建立可以反映岩土介质中孔隙的几何形态及空间连通性,为解释流体在复杂多孔介质中的流动特性提供有效手段。通过考虑岩土介质孔隙尺寸分布、孔隙孔喉空间相关性、孔隙连通性等特征参数,建立了反映不同岩土介质连通性、各向异性特征的等效孔隙网络模型。等效孔隙网络模型通过水力特征参数等效的方式反映岩土介质三维微观孔隙结构,通过渗透率计算验证了模型的有效性。此外,基于建立的孔隙结构模型,开发了孔隙尺度动态两相流计算模型,模型可以反映孔隙内弯液面的动态运动过程,直观反映多孔介质中的优势渗流,可以为不同孔隙尺度岩土介质提供表观渗透率、击穿曲线、相对渗透率曲线等宏观计算参数。将孔隙尺度两相流模型应用于页岩气开采中水力阻滞特性研究,结果表明:页岩基质的残余饱和度约为30%,随着平均配位数的增加,残余饱和度显著降低。

关键词：两相流等效孔隙网络模型相对渗透率页岩气优势渗流

nucleoside modified mRnA-lipid nanoparticles as a new delivery platform for the repair of the injured spinal cord

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neural Regeneration Research 2025年第8期20卷 2311-2312页

作者： Krisztián Pajer Tamás Bellák Antal nógrádi Department of Anatomy Histology and EmbryologyAlbert Szent-Györgyi Medical SchoolUniversity of SzegedSzegedHungary

Spinal cord injury and treatment opportunities:The adult mammalian spinal cord has a very limited capacity for spontaneous regeneration due to various intrinsic molecular and cellular *** the spinal cord neurons have the capacity to regenerate their axons,the expression of growth inhibitory factors,lack or suppression of proper guidance cues,and profound inflammatory responses do not permit successful regeneration(Khyeam et al.,2021).

关键词： injured capacity modified

Impacts of PI3K/protein kinase B pathway activation in reactive astrocytes: from detrimental effects to protective functions

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neural Regeneration Research 2025年第4期20卷 1031-1041页

作者： Ramón Pérez-núñez María Fernanda González Ana María Avalos Lisette Leyton Cellular Communication Laboratory Programa de Biología Celular y MolecularCenter for Studies on ExerciseMetabolism and Cancer(CEMC)Instituto de Ciencias Biomédicas(ICBM)Facultad de MedicinaUniversidad de ChileSantiagoChile Advanced Center for Chronic Diseases(ACCDiS) Faculty of Chemical and Pharmaceutical Sciences&Faculty of MedicineUniversidad de ChileSantiagoChile Instituto de Ciencias Biomédicas Facultad de Ciencias de la SaludUniversidad Autónoma de ChileSantiagoChile

Astrocytes are the most abundant type of glial cell in the central nervous *** injury and inflammation,astrocytes become reactive and undergo morphological and functional *** on their phenotypic classification as A1 or A2,reactive astrocytes contribute to both neurotoxic and neuroprotective responses,***,this binary classification does not fully capture the diversity of astrocyte responses observed across different diseases and *** analysis has revealed that reactive astrocytes have a complex landscape of gene expression profiles,which emphasizes the heterogeneous nature of their *** actively participate in regulating central nervous system inflammation by interacting with microglia and other cell types,releasing cytokines,and influencing the immune *** phosphoinositide 3-kinase(PI3K)/protein kinase B(AKT)signaling pathway is a central player in astrocyte reactivity and impacts various aspects of astrocyte behavior,as evidenced by in silico,in vitro,and in vivo *** astrocytes,inflammatory cues trigger a cascade of molecular events,where nuclear factor-κB serves as a central mediator of the pro-inflammatory ***,we review the heterogeneity of reactive astrocytes and the molecular mechanisms underlying their *** highlight the involvement of various signaling pathways that regulate astrocyte reactivity,including the PI3K/AKT/mammalian target of rapamycin(mTOR),αvβ3 integrin/PI3K/AKT/connexin 43,and notch/PI3K/AKT *** targeting the inactivation of the PI3K/AKT cellular signaling pathway to control reactive astrocytes and prevent central nervous system damage,evidence suggests that activating this pathway could also yield beneficial *** dual function of the PI3K/AKT pathway underscores its complexity in astrocyte reactivity and brain function *** review emphasizes the importance of employing astrocyte-exclusive models to underst

关键词： inflammation integrins neuroprotective neurotoxic phosphatidylinositol 3-kinase reactive astrocytes signal transduction Thy-1(CD90)

Astrocytes, reactive astrogliosis, and glial scar formation in traumatic brain injury

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neural Regeneration Research 2025年第4期20卷 973-989页

作者： María Belén Cieri Alberto Javier Ramos Laboratorio de neuropatología Molecular IBCN UBA-CONICETFacultad de MedicinaUniversidad de Buenos AiresBuenos AiresArgentina

Traumatic brain injury is a global health crisis,causing significant death and disability *** that follows traumatic brain injury has serious consequences for neuronal survival and cognitive impairments,with astrocytes involved in this *** traumatic brain injury,astrocytes rapidly become reactive,and astrogliosis propagates from the injury core to distant brain *** astroglial proteins are downregulated near the traumatic brain injury core,while pro-inflammatory astroglial genes are *** altered gene expression is considered a pathological remodeling of astrocytes that produces serious consequences for neuronal survival and cognitive *** addition,glial scar formed by reactive astrocytes is initially necessary to limit immune cell infiltration,but in the long term impedes axonal reconnection and functional *** therapeutic strategies for traumatic brain injury are focused on preventing acute ***,cannabinoids,progesterone,beta-blockers,and cerebrolysin demonstrate neuroprotective benefits but most of them have not been studied in the context of *** this review,we discuss the cell signaling pathways activated in reactive astrocytes following traumatic brain injury and we discuss some of the potential new strategies aimed to modulate astroglial responses in traumatic brain injury,especially using cell-targeted strategies with miRnAs or lncRnA,viral vectors,and repurposed drugs.

关键词： astrocyte glial scar innate immunity neuroinflammation stab injury Toll-like receptors