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Temporal and elevation trends in rainfall erosivity on a 149 km2watershed in a semi-arid region of the American Southwest

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International Soil and Water conservation Research 2015年第2期3卷 77-85页

作者： Mark A.Nearingn carl L.Unkrich dave c.goodrich Mary H.Nichols Tim O.Keefer USDA-ARS Southwest Watershed Research center 2000 E Allen RoadTucsonAZ 85719USA

Temporal changes in rainfall erosivity can be expected to occur with changing climate and because rainfall amounts areknown to bein pait of afunction of elevation erosivity can be expected to be influenced by elevation as *** is particularly truein mountainous regions such as are found over much of the westem United *** objective of this study was to identify temporal and elevation trends in rainfall erosivity on a 149km^(2)(58 miles)watershed in a semi-arid region of southeastem Arizona Data from 84 rain gages forthe years 19602012 at elevations ranging from 1231 to 1644 m(40385394 ft)were used in the *** average annual erosivity over the watershed as a whole was 1104 MJ mm ha^(-1)h^(-1)yr^(-1)(65 hundreds of foot ton inch acrei h^(-1)yr^(-1)),and ranged from approximately 950 to 1225 MJ mm ha^(-1)h^(-1)yr^(-1)(56-72 hundreds of foot ton inch acre^(-1)h^(-1)yr^(-1)),with a statistical trend showing greater erosivity af the higher elevations No statistically significant temporal changes in annual or summer erosivities were *** result stands in contrast to fecent modeling studies of runoff and erosion in the area based on downscaled GcM information that project significant levels of erosivity changes over coming *** results are consistent with known orographic rainfall effects,but contrast with recent studies that presented projections of significant trends of increasing erosivity in the future based on downscaled GcM outputs for the area The results illustiate the need for testing and developing improved techniques to evaluate future erosion scenarios for purposes of making targeted soil conservation decisions Production and Hosting by Elsevier B.V on behalf of International Research and Training center on Erosion and Sedimentation and china Water and Power Press This is anopen access article under theccBY-Nc-ND licens(http://***/licenses/by-ncnd/4.0/).

关键词： climate change R-factor RUSLE Semiarid Soil erosion Walnut Gulch

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Towards global coverage of gridded parameterization for cLImate GENerator(cLIGEN)

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Big Earth Data 2024年第1期8卷 142-165页

作者： Andrew T.Fullhart Guillermo E.Ponce-campos Menberu B.Meles Ryan P.McGehee Haiyan Wei Gerardo Armendariz Shea Burns David c.goodrich Southwest Watershed Research center USDA-ARS TucsonAZUSA School of Natural Resources and the Environment University of ArizonaTucsonAZUSA Sustainable Agricultural Water Systems Unit USDA-ARS DavisCAUSA Agricultural and Biosystems Engineering Iowa State UniversityAmesIAUSA

Stochastic weather generators create time series that reproduce key weather dynamics present in long-term *** dataset detailed herein is a large-scale gridded parameterization for cLImate GENerator(cLIGEN)that fills spatial gaps in the coverage of existing regional cLIGEN parameterizations,thereby obtaining near-global availability of combined *** dataset primarily covers countries north of 40°latitude with 0.25°spatial *** cLIGEN parameters were estimated based on 20-year records from four popular global climate *** parameters were statistically downscaled to estimate point-scale values,while point-scale temperature and solar radiation parameters were approximated by direct calculation from high-resolution *** parameter values were used in some cases,such as with wind ***-validation was done to assess the downscaling approach for six precipitation parameters using known point-scale values from ground-based cLIGEN *** parameter values were derived from daily accumulation records at 7,281 stations and high temporal resolution records at 609 *** sensitive parameters,monthly average storm accumulation and maximum 30-minute intensity,were shown have RMSE values of 1.48 mm and 4.67 mm hr^(−1),*** precipitation and the annual number of days with precipitation occurrence were both within 5%of ground-based parameterizations,effectively improving climate data availability.

关键词： Agriculture climate hydrology soil erosion stochastic weather generator

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Mantle avalanches in a Venus-like stagnant lid planet

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Earth and Planetary Physics 2024年第5期8卷 686-702页

作者： Madeleine c.Kerr dave R.Stegman Institute of Geophysics and Planetary Physics Scripps Institution of Oceanography University of California

Stagnant lid planets are characterized by a globe-encircling, conducting lid that is thick and strong, which leads to reduced global surface heat flows. consequently, the mantles of such planets can have warmer interiors than Earth, and interestingly, a pyrolitic mantle composition under warmer conditions is predicted to have a distinctly different mantle transition zone compared to the present-day Earth(Hirose, 2002; Stixrude and Lithgow-Bertelloni, 2011; Ichikawa et al., 2014; Dannberg et al, 2022). Instead of olivine primarily transforming into its higher-pressure polymorphs such as wadsleyite and then ringwoodite, at pressures corresponding to410 km and 520 km depth in Earth, respectively, it instead transforms into a mineral assemblage of wadsleyite, majorite, and ferropericlase(WMF), and then to majorite + ferropericlase(MF), before finally transforming into bridgmanite at pressures corresponding to 660 km depth in Earth(Stixrude and Lithgow-Bertelloni, 2011; Ichikawa et al., 2014). convective motions in stagnant lid planets are dominated by small-scale instabilities(cold drips) forming within the mobile rheological sublayer under the rigid lid. Using ASPEcT and a thermodynamic model of a pyrolitic mantle composition generated by HeFESTo, we show that under certain conditions, the small drips can pond atop the WMF-MF mineral phase transition. The barrier to convective flow arises from the WMF mineral phase assemblage having an effective negative thermal expansivity(Stixrude and Lithgow-Bertelloni, 2022). Although large-scale downwellings that typically occur within mobile lid planets are able to pass through the WMF zone without difficulty(Dannberg et al., 2022; Li RP et al.,2024), the smaller and less negatively buoyant nature of downwelling drips in stagnant lid planets are more susceptible to these effects,which leads to an ephemeral layering of the mantle. Our numerical models show that in stagnant lid planets with mantle potential temperatures that exceed

关键词： Venus mantle avalanches numerical modelling phase transitions

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Atlas of precipitation extremes for South America and Africa based on depth-duration-frequency relationships in a stochastic weather generator dataset

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International Soil and Water conservation Research 2023年第4期11卷 726-742页

作者： Andrew Fullhart David c.goodrich Menberu B.Meles Paulo Tarso S.Oliveira cristiano das Neves Almeida Joséc.de Araújo Shea Burns Southwest Watershed Research center USDA-ARS 2000 E.Allen Rd.TucsonAZ85719United States Sustainable Agricultural Water Systems Unit USDA-ARS 239 Hopkins RoadDavisCA95616United States Faculty of Engineering Architecture and Urbanism and GeographyUniversidade Federal de Mato Grosso do SulCampo GrandeMS79070-900Brazil Water Resources and Environmental Engineering Laboratory Universidade Federal da ParaíbaJoao PessoaPB58051-900Brazil Department of Agricultural Engineering campus do Pici Fortaleza Universidade Federal do CearáFortaleza60020-181Brazil

Information about extreme rainfall is lacking in regions of South America and *** study attempts to fill this scientific gap by use of a gridded parameterization for the stochastic weather generator,cLIGEN,to map depth-duration-frequency(DDF)*** of 500-year point-scale precipitation time series generated at each grid point allowed maps of return period precipitation to be produced for a se-lection of sixteen durations ranging from 10-min to 1-year and for nine return periods from 2 to 500 *** generalized extreme value(GEV)probability distribution was fitted for all durations,and given GEV quantiles,an interpolation method was applied to produce maps at 0.1° resolution that better resolve small-scale spatial climate *** addition to uncertainties related to GEV fitting,this study quantifies prediction intervals based on ground *** validation was important for identifying biases in cLIGEN,although uncertainties were not always satisfactorily defined due to sampling design and other *** daily/multi-day durations,100 stations with daily observations and ≥50-year records were selected for validation against the 0.1° cLIGEN map series,resulting in a median and average absolute error of 13%and 16%,*** sub-daily durations,prediction errors were larger *** analogy using available *** established the degree of bias in cUGEN for sub-daily durations,and three records in Brazil with high temporal resolutions were used to confirm that applied bias adjustments resulted in error ranges similar to the daily/multi-day *** atlas is freely available for study of extreme precipitation.

关键词： Africa Depth-duration-frequency Extreme precipitation South America

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Gridded 20-year climate parameterization of Africa and South America for a stochastic weather generator (cLIGEN)

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Big Earth Data 2023年第2期7卷 349-374页

作者： Andrew Fullhart Guillermo E.Ponce-campos Menberu B.Meles Ryan P.McGehee Gerardo Armendariz Paulo Tarso S.Oliveira cristiano Das Neves Almeida José c.de Araújo Werner Nel David c.goodrich Southwest Watershed Research center USDA-ARS TucsonAZUSA School of Natural Resources and the Environment University of ArizonaTucsonAZUSA Sustainable Agricultural Water Systems Unit USDA-ARS DavisCAUSA Agricultural and Biological Engineering Purdue UniversityWest LafayetteINUSA Faculty of Engineering Architecture and Urbanism and GeographyFederal University of Mato Grosso do Sul(UFMS)Campo GrandeMSBrazil Water Resources and Environmental Engineering Laboratory Federal University of ParaíbaJoao PessoaPBBrazil Federal University of Fortaleza Department of Agricultural EngineeringFortalezaBrazil Department of Geography and Environmental Science University of Fort HareAliceSouth Africa

cLIGEN is a stochastic weather generator that creates statistically representative timeseries of daily and sub-daily point-scale weather variables from observed monthly statistics and other parameters. cLIGEN precipitation timeseries are used as climate input for various risk-assessment modelling applications as an alternative to observe long-term, high temporal resolution records. Here, we queried gridded global climate datasets (Terraclimate, ERA5, GPM-IMERG, and GLDAS) to estimate various 20-year climate statistics and obtain complete cLIGEN input parameter sets with coverage of the African and South American continents at 0.25 arc degree resolution. The estimation of cLIGEN precipitation parameters was informed by a ground-based dataset of >10,000 locations worldwide. The ground observations provided target values to fit regression models that downscale cLIGEN precipitation input parameters. Aside from precipitation parameters, cLIGEN’s parameters for temperature, solar radiation, etc. were in most cases directly calculated according to the original global datasets. cross-validation for estimated precipitation parameters quantified errors that resulted from applying the estimation approach in a predictive fashion. Based on all training data, the RMSE was 2.23 mm for the estimated monthly average single-event accumulation and 4.70 mm/hr for monthly maximum 30-min intensity. This dataset facilitates exploration of hydrological and soil erosional hypotheses across Africa and South America.

关键词： climate cLIGEN Africa South America

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Microstructural characteristics and Mechanical Properties of Low-Alloy, Medium-carbon Steels After Multiple Tempering

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Acta Metallurgica Sinica(English Letters) 2019年第1期32卷 74-88页

作者： Erfan Abbasi Quanshun Luo dave Owens Materials and Engineering Research Institute Sheffield Hallam University Tyzack Machine Knives Ltd

The microstructure and mechanical properties of NicrMoV-and NicrSi-alloyed medium-carbon steels were investigated after multiple tempering. After austenitising, the steels were hardened by oil quenching and subsequently double or triple tempered at temperatures from 250 to 500 °c. The samples were characterised using scanning electron microscopy and X-ray diffraction, while the mechanical properties were evaluated by Vickers hardness testing, V-notched charpy impact testing and tensile testing. The results showed that the retained austenite was stable up to 400 °c and the applied multiple tempering below this temperature did not lead to a complete decomposition of retained austenite in both steels. It was also found that the microstructure, hardness and impact toughness varied mainly as a function of tempering temperature,regardless of the number of tempering stages. Moreover, the impact toughness of NicrMoV steel was rather similar after single/triple tempering at different temperatures, while NicrSi steel exhibited tempered martensite embrittlement after single/double tempering at 400 °c. The observed difference was mainly attributed to the effect of precipitation behaviour due to the effect of alloying additions in the studied steels.

关键词： Medium-carbon steels Multiple tempering Alloying addition Mechanical properties Retained austenite Precipitation behaviour

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Evaluation of the cracking and aging susceptibility of asphalt mixtures using viscoelastic properties and master curve parameters

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Journal of Traffic and Transportation Engineering(English Edition) 2022年第1期9卷 106-119页

作者： Runhua Zhang Jo E.Sias Eshan V.dave Department of civil and Environmental Engineering University of New HampshireDurhamNH 03824USA

Aging can significantly affect the performance of asphalt mixtures, causing increase in stiffness, reduction in relaxation capability and increase in cracking susceptibility. It is also well known that fundamental viscoelastic properties are used for design and modelling of asphalt mixtures and pavement structures to addressing rutting, fatigue and thermal cracking concerns. The objective of this paper is to study how the viscoelastic properties of asphalt mixture change over time, and evaluate and identify the cracking and aging susceptibility of asphalt mixtures with different mix variables during material selection and mixture design. Ten mixtures are evaluated using different laboratory conditioning protocols to simulate a range of aging levels in the field. The complex modulus test is then conducted on the lab aged mixtures to measure the viscoelastic properties in order to construct the dynamic modulus and phase angle master curves. The mixture Glover-Rowe(G-Rm) parameter and the shape parameters of the dynamic modulus and phase angle master curves, including inflection point frequency(-β/γ), difference between the glassy modulus and the inflection point modulus(γ), peak value of phase angle(a) and the horizontal position(frequency) of the peak phase angle value(c), are determined and evaluated for the mixtures with different aging conditions and mix variables. The study indicates the ability of the G-Rmparameter and all the master curve shape parameters to capture the effect of different aging conditions on linear viscoelastic mixture properties, as well as the cracking and aging susceptibility of asphalt mixtures.

关键词： Asphalt mixture Viscoelastic properties complex modulus and phase angle master curve Master curve shape parameters Aging susceptibility cracking susceptibility

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Antioxidant potential and physicochemical properties of protein hydrolysates from body parts of North Atlantic sea cucumber(cucumaria frondosa)

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Food Production, Processing and Nutrition 2021年第1期3卷 48-69页

作者： Tharindu R.L.Senadheera Deepika dave Fereidoon Shahidi Department of Biochemistry Memorial University of NewfoundlandSt.John’sNL A1B 3X9Canada Marine Bioprocessing Facility Centre of Aquaculture and Seafood DevelopmentFisheries and Marine InstituteMemorial University of NewfoundlandSt.John’sNL A1C 5R3Canada

Protein hydrolysates were prepared from North Atlantic sea cucumber(cucumaria frondosa)body wall(BW),and processing by-product flower(FL)and internal organs(IN).Sea cucumber proteins from these three tissues were hydrolysed with selected endopeptidases and *** enzymes used were Alcalase(A),and corolase(c)as endopeptidases and Flavourzyme(F)with both endo-and exopeptidase *** were employed individually or in combination under controlled *** hydrolysates so prepared were subsequently analysed for their antioxidant potential and functionalities in food systems for the first *** treated with the combination of A and F exhibited the highest radical scavenging activity against DPPH and ABTS *** highest metal chelation activity was observed for samples hydrolysed with the combination of enzymes(c+F and A+F).All treatments inhibited beta-carotene bleaching in an oil-in-water emulsion and TBARS production in a meat model *** addition,sea cucumber protein hydrolysates were more than 75%soluble over a pH range of 2–*** proteins were also effective in enhancing water holding capacity in a meat model system compared to their untreated *** amino acids of sea cucumber protein hydrolysates had desirable profiles with glutamic acid as the predominant component in samples *** findings demonstrate the desirable functionalities of hydrolysates from North Atlantic sea cucumber and their potential for use as functional food ingredients.

关键词： Sea cucumber Protein hydrolysates Antioxidant activity Physicochemical properties

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Numerical investigation of the hydraulic fracturing mechanisms in oil sands

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Underground Space 2021年第2期6卷 195-216页

作者： Siavash Taghipoor Morteza Roostaei Arian Velayati Atena Sharbatian dave chan Alireza Nouri Department of civil and Environmental Engineering University of AlbertaCanada KGHM International 1010 Lorne StSudburyON P3C 4R9Canada RGL Reservoir Management Inc. 690842 StLeducAB T9E 0R8Canada

This paper presents a numerical investigation of hydraulic fracturing in oil sands during cold water injection by considering the aspects of both geomechanics and reservoir fluid *** to previous studies,the low shear strengths of unconsolidated or weakly consolidated sandstone reservoirs significantly influence the hydraulic fracturing ***,classical hydraulic fracture models cannot simulate the fracturing process in weak sandstone *** the current numerical models,the direction of a tensile fracture is predetermined based on in situ stress ***,the potential transformation of a shear fracture into a tensile fracture and the potential reorientation of a tensile fracture owing to shear banding at the fracture tip have not yet been addressed in the *** this study,a smeared fracture technique is employed to simulate tensile and shear fractures in oil *** model used combines many important fracture features,which include the matrix flow,poroelasticity and plasticity modeling,saturation-dependent permeability,gradual degradation of the oil sands as a result of dilative shear deformation,and the tensile fracturing and shear failure that occur with the simultaneous enhancement of ***,sensitivity analyses are also performed with respect to the reservoir and geomechanical parameters,including the apparent tensile strength and cohesion of the oil sands,magnitude of the minimum and maximum principal stress,absolute permeability and elastic modulus of the oil sands and ramp-up *** these analyses are performed to clarify the influences of these parameters on the fracturing response of the oil sands.

关键词： Smeared fracture Hydraulic fracturing Numerical simulation Oil sand

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作者： dave c.[等]

来源：南通市图书馆图书评论

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