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material Research Related to Structural Pavement Failure on motorway A32 in the Netherlands

武汉理工大学学报 2010年第17期32卷 8-17页

作者： HOUBEN L j m mOLENAAR A A A ERKENS S m j g Faculty Civil Engineering and geosciences Delft University of Technology ministry of Traffic Public Works and Water ManagementCentre for Transport and Navigation

In 2008 structural failures occurred on the asphalt pavement,with a hydraulic blast furnace slag base,of the motorway A32 (constructed in 1986～1988) in the Netherlands. Within a few weeks serious depressions occurred,in which the asphalt pavement was full of cracks and the base had a very low stiffness. In 2008 and 2009 the pavement including the base was rehabilitated over a length of 10 *** Dutch ministry of Public Works has initiated an extensive research into the risks of occurrence of this type of unexpected structural dam.g.s on the main road network in the Netherlands. Among many other things this research includes material research into the base material of the A32 to find the cause of the structural *** total 130 cores,divided over 26 cross-sections,were drilled from the A32. The cross-sections were divided over 3 areas,with a high and low base stiffness respectively and also at heaves that had grown into the pavement since 1998. In areas with high base stiffness the cores mainly contained bound base material,in areas with low base stiffness mainly granular material and at the heaves it was a mix thereof. Standard (static) and dynamic crushing tests were done on the granular material. Dynamic and monotonic indirect tensile tests and compression tests were performed on the bound material. In all cases no systematic difference was found between the mechanical properties of the blast furnace slag base material from the heavily loaded right traffic lane and the material from the other *** is concluded that the pavement failure on the A32 is introduced by the occurrence of full depth asphalt fatigue cracks in the pavement that was originally designed for 12 years (but was never strengthened) in areas where the base stiffness always has been low or became low through crushing (that also has resulted in the heaves). Penetrated rainwater then has weakened the base and pumping has occurred,resulting into loss of bearing capacity and decrease of vo

关键词： structural failure blast furnace slags base laboratory testing

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mineral dust resuspension under vibration: Onset conditions and the role of humidity

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Particuology 2020年第3期18卷 112-119页

作者： F.j.Balladore j.g.Benito R.O.Unac A.m.Vidales Departamento de mineria Facultad de Ciencias Fisico Matematicas y NaturalesUniversidad Nacional de San LuisChacabuco 917D5700HHWSan LuisArgentina INFAP CONICETDepartamento de FisicaFacultad de Ciencias Fisico Matematicas y NaturalesUniversidad Nacional de San LuisEjercito de los Andes 950D5700HHWSan LuisArgentina

The vibration of dusty surfaces inevitably causes re-entrainment of particles into the *** that movement of mineral dust particles deposited on a surface begins at a critical frequency (fc) and amplitude,an experimental laboratory study was conducted to determine the onset conditions for resuspension of a vibrated granular *** determined the resuspension state diagram as a function of frequency and amplitude of a sinusoidal vibration,the granulometry of the dust and the thickness of the soil *** mitigation effect of humidity was also *** frequencies ranged between 2.5 and 23 Hz when amplitudes were less than 12 *** results were independent of bed thickness and perturbation *** all particle sizes observed,fc decreased monotonically with A,contrasting with behavior observed for individual *** dry samples,fe for large size classes was markedly less when A was greater than 6 mm;while thefc for fine fractions only decreased once amplitudes reached 10 *** with wet granular soils demonstrated that wetting above an optimum humidity did not necessarily impede movement and caused *** study provides guidelines for managing resuspension of granular soils subjected to vibrations.

关键词： Resuspension Vibration granular soil mineral dust Critical frequency Humidity

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Predicting maximum Lifespan Limits at mean menopausal Age

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journal of mathematical Research with Applications 2025年第1期 133-142页

作者： m.SUmATHI S.ANTONY CARLA Department of mathematics N.M.S.S.Vellaichamy Nadar College Research Scholar (Part-time) Madurai Kamaraj University

The age at which a woman enters natural menopause has also been associated to death from any cause. menopause is a natural component of aging that happens between the ages of 45 and 55, with the average menopausal age being 51. Previous research has revealed the age at which women reach menopause, but there is no evidence to support the link between menopause and longevity. We made a study in assessing the limits of maximum lifespan at menopausal age in our previous article. In this paper, we aim to predict the maximum lifespan of women at mean menopausal age.

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;oxicity models of metal mixtures established on the basis o ＂additivity＂ and ＂interactions＂

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Frontiers of Environmental Science & Engineering 2017年第2期11卷 11-23页

作者： Yang Liu martina g. Vijver Bo Pan Willie j. g. m. Peijnenburg Faculty of Environmental Science and Engineering Kunming University of Science and Technology Kunming 650500 China Institute of Environmental Sciences (CmL) Leiden University Leiden 2300 RA The Netherlands National Institute of Public Health and the Environment (RIVm) Center for Safety of Substances and Products Bilthoven 3720 BA The Netherlands

Observed effects of metal mixtures on animals and plants often differ from the estimates, which are commonly calculated by adding up the biological responses of individual metals. This difference from additivity is commonly referred to as being a consequence of specific interactions between metals. The science of how to quantify metal interactions and whether to include them in risk assessment models is in its infancy. This review summarizes the existing predictive tools for evaluating the combined toxicity of metals present in mixtures and indicates the advantages and disadvantages of each method. We intend to provide eco-toxicologists with background information on how to make good use of the tools and how to advance the methods for assessing toxicity of metal mixtures, It is concluded that statistically significant deviations from additivity are not necessarily biologically relevant. Incorporation of interactions between metals in a model does not on forehand mean that the model is more accurate than a model developed based on additivity only. It is recommended to first use a relatively simple method for effect prediction of uninvestigated metal mixtures. To improve the reliability of toxicity modeling for metal mixtures, further efforts should focus on balancing the relationship between the significance of statistics and the biological meaning, and unraveling the toxicity mechanisms of metals and their mixtures.

关键词： metal mixtures Toxicity Additivity modeling Interactions

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Significance of Experimental Data in the Design of Structures made from 1.4057 Steel

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journal of Wuhan University of Technology(materials Science) 2014年第1期29卷 131-136页

作者： Brnic j Turkalj g NIU jitai Canadija m Lanc D Department of Engineering mechanics Faculty of Engineering University of Rijeka School of materials Science and Engineering Harbin Institute of Technology School of materials Science and Engineering Henan Polytechnic University

This paper presents experimentally-obtained data which can be of importance in the design procedure of engineering components made of 1.4057 （X 17CrNil 6-2; AISI 431） steel. In this manner, uniaxialy tests related to determine material mechanical properties and short-time creep behavior were performed. Based on the mentioned tests, ultimate tensile strength, 0.2 offset yield strength and modulus of elasticity at low and elevated temperatures were determined. Also, creep behavior of considered steel was tested for selected temperatures and selected stress levels. According to experimentally determined Charpy impact energy an assessment of fracture toughness was made.

关键词： material properties short-time creep fracture toughness calculation 1.4057 steel

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Paleoenvironments and geochemistry across a continuous Permian-Triassic boundary section at Bukk mountains,Hungary

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geoscience Frontiers 2021年第3期12卷 214-233页

作者： m.E.Brookfield j.C.Williams A.g.Stebbins School for the Environment University of MassachusettsBostonMA 02125USA School of Earth Sciencec The Ohio State UniversityColumbusOH 43210USA

The Bálvány North Permian-Triassic boundary sediments were deposited on a carbonate platform in the tropical part of the western Paleo Tethys *** overall elemental geochemistry of the detailed two-metre-thick section across the boundary that we studied shows that the clastic content of the sediments came from dominantly silica-rich continental sources though with some more silica-poor inputs in the uppermost Permian and lowest Triassic limestones as shown by Ni/Al and Nb/Ta *** inputs bracket,but do not coincide with,the main extinctions and associated C,O and S *** aridity at the Permian-Triassic boundary with increased wind abrasion of suitable Ti-bearing heavy minerals accounts for both the high Ti/Al and Ti/Zr *** geochemical redox proxies suggest mainly oxic depositional conditions,with episodes of anoxia,but with little systematic variation across the Permian-Triassic extinction *** lack of consistent element geochemical changes across the Permian-Triassic boundary occur not only in adjacent shallower-water marine sections,and in other marine sections along the SW Tethys margin such as the Salt Range sections in Pakistan,but also in deeper shelf and oceanic sections,and in non-marine African and European continental *** the absence of significant changes in physical environments,chemical changes in the atmosphere and oceans,reflected in various isotopic changes,drove the Permian-Triassic extinctions.

关键词： Permian-Triassic boundary Paleoenvironments geochemistry Hungary Bukk

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Evolution of deformation twins with strain rate in a mediummanganese wear-resistant steel Fe-8mn-1C-1.2Cr-0.2V

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journal of Iron and Steel Research International 2019年第9期26卷 983-990页

作者： j. Chen j.j.Wang H.Zhang W.g.Zhang C.m.Liu Key Laboratory for Anisotropy and Texture of materials Ministry of EducationNortheastern UniversityShenyang 110819LiaoningChina School of materials Science and Engineering Northeastern UniversityShenyang 110819LiaoningChina Baosteel Special Steel Co. Ltd.Shanghai 200940China Northeastern Institute of metal materials Co. Ltd.Shenyang 110108LiaoningChina

microstructure evolutions of the medium-manganese wear-resistant steel Fe-8mn-1C-1.2Cr-0.2V (in wt.%) with stacking-fault energy of 22 mj m-2 during deformation at strain rate ranging of 10^-2-1 s^-1 were analyzed by means of X-ray diffraction, field emission scanning electron microscopy and high-resolution transmission electron microscopy. The results indicate that the twinning-induced plasticity effect is the main strengthening mechanism of the studied steel, whilst the transformation-induced plasticity effect only occurs at high strain rate. With an increase in strain rate, volume fraction of the deformation twins, in particular that of the secondary twins, increases significantly along with decreasing average size. When applied strain rate is higher than 10^-1 s^-1, the parallel deformation twins are turned into a crossing morphology, and the original straight twin boundaries exhibit a ladder feature, which is attributed to the interactions between regular dislocations and twin dislocations at the twin boundary. The critical strain, a key indicator of the initiation of deformation twin, decreases with increasing strain rate. In addition, the ductility and strength of medium-manganese wear-resistant steel Fe-8mn-1C-1.2Cr-0.2V are mainly determined by the shape and volume fraction of deformation twins.

关键词： medium-manganese wear-resistant steel Stacking fault Twinning-induced plasticity effect Secondary twin Strain hardening rate

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microwave sintered porous CoCrFeNimo high entropy alloy as an efficient electrocatalyst for alkaline oxygen evolution reaction

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journal of materials Science & Technology 2021年第20期79卷 171-177页

作者： j.Tang j.L.Xu Z.g.Ye X.B.Li j.m.Luo School of materials Science and Engineering Nanchang Hangkong UniversityNanchang330063China

Developing efficient,stable and economical electrocatalyst for oxygen evolution reaction(OER)is a significant pathway to produce clean energy from water ***,the promising and highly efficient porous CoCrFeNimo high entropy alloys(HEAs)were prepared by microwave sintering using mg space *** to unique properties of high entropy alloys and abundant active surface area,the porous CoCrFeNimo-20 mg exhibits excellent catalytic performance and prominent electrochemical stability with a low overpotential of 220 mV to reach current density of 10 mA cm^(-2),a small Tafel slope of 59.0 mV dec^(-1) and long-term durability for 24 h in 1.0 m *** results of microstructure and element states indicate that crystal defects,porous structure and villous hydroxides are the reasons for high OER performance of the *** work not only provides a new way to prepare electrocatalysts,but also proves the important application of high entropy alloys in functional materials.

关键词： CoCrFeNimo High entropy alloys Electrocatalysts Oxygen evolution reaction microwave sintering mg space holder

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Analysis of the hydrological safety of dams combining two numerical tools:Iber and DualSPHysics

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journal of Hydrodynamics 2018年第1期30卷 87-94页

作者： j.gonzález-Cao O.garcía-Feal j.m.Domínguez A.j.C.Crespo m.g.mez-gesteira Environmental Physics Laboratory (EPHYSLAB) Universidade de Vigo Campus AsLagoas

The upgrade of the hydrological safety of dams is a critical issue to avoid failures that can dramatically affect people and assets. This paper shows a numerical methodology to analyse the safety of the Belesar dam（NW, Spain） based on two different numerical codes. First, a mesh-based code named Iber, suited to deal with large 2-D domains, is used to simulate the impoundment. The initial conditions and the inlet provided to Iber correspond to the maximum water elevation and the maximum expected inflow to the impoundment defined in the technical specifications of the dam, which are associated to the more hazardous operation conditions of the dam. Iber provides information about the time needed for water to attain the crest of the dam when floodgates are closed. In addition, it also provides the velocity of discharge when gates are opened. Then, a mesh-free code named DualSPHysics, which is especially suited to deal with complex and violent 3-D flows, is used to reproduce the behaviour of one of the spillways of the dam starting from the results obtained with Iber, which are used as inlet conditions for DualSPHysics. The combined results of both model show that the left spillway can discharge the surplus of water associated to the maximum inflow to the reservoir if the gates of the spillways are opened before the overtopping of the dam was observed. In addition, water depth measured on the spillway is considerably lower than the lateral walls, preventing overtopping. Finally, velocities at different points of the spillway showed to be in good agreement with theoretical values.

关键词： Hydrological safety dam numerical simulation Iber DualSPHysics

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氧化矿石浮选法

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1958年

作者：（英）m.g.傅勒铭等

来源：汇雅图书（南通市图书馆... 评论

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