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Hydrologic Time Scale:A Fundamental Stream Characteristic

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Journal of earth Science 2022年第5期33卷 1291-1297页

作者： Robert e.Criss Department of earth and Planetary Sciences Washington University in St.LouisSt.LouisMO63130USA

A new,fundamental catchment attribute called the hydrologic time scaleτgoverns the rate of delivery of runoff to a particular site,and is equal to∫Qdt/∫|dQ|,where Q is discharge and t is *** value ofτfor any gauged site is readily calculated from tabulated discharge data by replacing the integrals with *** quantity,coupled with the square root of catchment area,√A,form a coordinate pair that embodies the characteristic time and length scales for any catchment,which govern its flow *** fitting constants used in several unit hydrograph models are simple multiples ofτ,so knowledge ofτallows rapid calibration of these models for the particular site,facilitating flow prediction from rainfall *** ofτreflect many different landscape attributes,but for multiple sub-basins in watersheds with homogeneous land use and lithologic conditions,they correlate linearly with √*** ratio √A/τprovides a characteristic velocity that is high for channelized,floodprone rivers,for flashy urban streams with high impervious cover,and for sites downstream of hydropower *** with low velocities are resistant to flooding,as their landscapes have a greater ability to delay the delivery of runoff by retention,detention,and infiltration into the groundwater system.

关键词： unit hydrograph time constant flash floods impervious cover urban streams flashiness hydrogeology

Are hydrides under high-pressure-high-temperature superconductors?

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National Science Review 2024年第7期11卷 9-12页

作者： J.e.Hirsch Department of Physics University of California

Contrary to the current consensus, I argue that the existing evidence for high-temperature superconductivity in hydrides under high pressure is not compelling. I suggest that the focus of the field should urgently shift to establish unequivocally experimentally whether or not superconductivity in pressurized hydrides exists, instead of continuing to search for new materials that might show elusive signals of unproven superconductivity at ever higher temperatures. The implications of a negative finding for the theoretical understanding of superconductivity are discussed.

关键词： Hydrides

estimating costs of salvage logging for large-scale burned forest lands: A case study on Turkey's Mediterranean coast

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Journal of Forestry Research 2021年第5期32卷 1899-1909页

作者： Neşe Gülci Faculty of Forestry Kahramanmaras Sutcu Imam University46100 KahramanmarasTurkey

Different forest fires causing different degrees of effects occur in fire-sensitive forests due to various reasons such as climate *** as well as harmful aspects of forest fires are a multi-disciplinary research *** information systems(GIS)and remote sensing(RS)methods offer a number of benefits for researchers and operators in the field of forest fire *** present study analyses timber pricing based on forest contractor demands of post-salvage logging *** effect of timber obtained from compartment units on producers’pricing policy was *** forest fire area(2500 ha)located in Antalya in Turkey was selected as the main study *** parameters(aspect,slope and slope position),stand types(diameter class and crown closure),and burn severity were analyzed together using GIS and R software packages.A multi-linear regression model(R^(2)=0.752)demonstrated that factors that had the most impact on pricing were slope position,aspect,stand age,crown closure and burn *** model can be used to estimate salvage logging prices in Calabrian pine(Pinus brutia Ten.)stands with similar *** administrators and contractors may readily address the unit price of timber by estimating approximate costs in a given forest area for which they are going to *** will help reduce operational planning times of harvesting procedures in burned stands.

关键词： Timber extraction Forest fires Stumpage sale Cost estimation Sustainability Crown fire

Influence of the Choice of NN Potential Model on γd→τ~0d Observables near η-Threshold

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Chinese Physics Letters 2016年第4期33卷 14-18页

作者： e.M.Darwish Physics Department Faculty of ScienceTaibah University Physics Department Faculty of ScienceSohag University

Influence of the choice of the NN potential model governing the deuteron wave function on the observables for coherent π0-photoproduction on the deuteron near η-threshoM is investigated by using a three-body model for the intermediate ηN N system with separable two-body interactions. Results for unpolarized differential cross section and polarization observables are predicted. It is revealed that the choice of the NN potential model has a visible effect on the differential cross section and most of the polarization observables, especially in the photon energy range of 600-800 MeV and extreme backward pion angles. We find that the deviation among results obtained by using different deuteron wave functions is quite large. The use of the CD-Bonn NN potential for deuteron wave function doubles the differential cross section in this kinematic region. Compared with the experimental data from CLAS collaboration for differential cross section, sizeable discrepancies are found.

关键词： of in Observables near Threshold NN that for on CLAS

exploring the mass gap:Black holes in green pea galaxies

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Science China(Physics,Mechanics & Astronomy) 2024年第10期67卷 170-171页

作者： James e.Rhoads School of earth and Space exploration Arizona State UniversityTempeAZ 85287USA

We know about black holes primarily on two mass scales(e.g.,see Figure 22 of ref.[1]).Supermassive black holes inhabit the centers of galaxies,where they sometimes power active galactic nuclei(AGN).Their populations can be probed through AGN surveys,tidal disruption event surveys,and(in the closest galaxies)stellar and gas dynamics in the innermost regions where the black hole dominates the gravitational potential.

关键词： galaxies tidal galactic

effect of water on behaviour of Na_2B_4O_7·5H_2O and Na_2B_4O_7 in HCl-CH_3OH medium

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Transactions of Nonferrous Metals Society of China 2010年第8期20卷 1541-1544页

作者： A.e.eRTAS .GIRGIN Mining engineering Department Hacettepe University

The reactivity of Na2B4O7·5HaO and Na2B4O7 in non-aqueous HCl-CH3OH solvent system was investigated. The effects of H2O, CH3OH/B mole ratio and reaction time on the reaction at room temperature were examined. experimental results show that when Na2B4O7·5H2O and Na2B4O7 are the reactants, the dissolved B203 contents are observed to be 98.2% and 99%, respectively, in 5min at the CH3OH/B mole ratio of 4. The decrease of water in the reaction medium was observed to increase the crystallization of NaCI in the order of Na2B4O7〉Na2B4O7·5H2O It was also observed that the boron solution obtained after the reaction could be hydrolyzed by the addition of H3BO3. The results show that HCl-CH3OH system is a more effective solvent compared to H2SO4-CH3OH both in the reactivity and the shortened reaction time.

关键词： non-metallic ores oxide ores hydrometallurgy leaching

ASYMPTOTIC LIMITS AND STABILIZATION FOR THe 1D NONLINeAR MINDLIN-TIMOSHeNKO SYSTeM

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Journal of Systems Science & Complexity 2010年第3期23卷 414-430页

作者： F.D.ARARUNA P.BRAZ e SILVA e.ZUAZUA Departamento de Matemática Universidade Federal da Paraíba Departamento Ikerbasque Research Professor Basque Center for Applied Mathematics(BCAM)

This paper shows how the so called von Karman model can be obtained as a singular limit of a modified Mindlin-Timoshenko system when the modulus of elasticity in shear κ tends to infinity, provided a regularizing term through a fourth order dispersive operator is added. Introducing damping mechanisms, the authors also show that the energy of solutions for this modified Mindlin-Timoshenko system decays exponentially, uniformly with respect to the parameter k. As κ→∞, the authors obtain the damped von Karman model with associated energy exponentially decaying to zero as well.

关键词： Mindlin-Timoshenko system singular limit uniform stabilization vibrating beams von Karman system.

exact Solutions of Kolmogorov-Petrovskii-Piskunov equation Using the Modified Simple equation Method

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Acta Mathematicae Applicatae Sinica 2014年第3期30卷 749-754页

作者： e.M.e.Zayed S.A.Hoda Ibrahim Mathematics Department Faculty of ScienceZagazig University

The modified simple equation method is employed to find the exact solutions of the nonlinear Kolmogorov-Petrovskii-Piskunov （KPP） equation. When certain parameters of the equations are chosen to be special values, the solitary wave solutions are derived from the exact solutions. It is shown that the modified simple equation method provides an effective and powerful mathematical tool for solving nonlinear evolution equations in mathematical physics.

关键词： modified simple equation method Kolmogorov-Petrovskii-Piskunov equation exact solutions solitary wave solutions

SOMe OSCILLATION CRITeRIA FOR SeCOND ORDeR NONLINeAR FUNCTIONAL ORDINARY DIFFeReNTIAL eQUATIONS

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Acta Mathematica Scientia 2007年第3期27卷 602-610页

作者： e.M.e.Zayed M.A.el-Moneam Mathematics Department Faculty of ScienceZagazig UniversityZagazigEgypt

The main objective of this article is to study the oscillatory behavior of the solutions of the following nonlinear functional differential equations（a（t）x＇（t））＇＋δ1p（t）x＇（t）＋δ2q（t）f（x（g（t））） = 0,for 0 ≤ to≤ t, where 51 = ：el and δ±1. The functions p,q,g ： [t0, ∞） → R, f ： R → are continuous, a（t）〉 0,p（t） ≥0,q（t）〉 0 for t ≥ to,lirn g（t） = ∞, and q is not identically zero on any subinterval of [to, ∞）. Moreover, the functions q（t）, g（t）, and a（t） are continuously differentiable.

关键词： Oscillatory and nonoscillatory solutions nonlinear functional differential equations